Sample records for agonists glp-1 ra

  1. GLP-1 agonists for type 2 diabetes: pharmacokinetic and toxicological considerations.

    PubMed

    Jespersen, Maria J; Knop, Filip K; Christensen, Mikkel

    2013-01-01

    Within recent years, glucagon-like peptide 1 receptor agonists (GLP-1-RA) have emerged as a new treatment option for type 2 diabetes. The GLP-1-RA are administered subcutaneously and differ substantially in pharmacokinetic profiles. This review describes the pharmacokinetics and safety aspects of the currently available GLP-1 receptor agonists, liraglutide (based on the structure of native GLP-1), exenatide twice daily and exenatide once weekly (based on exendin-4) in relation to the kinetics and toxicology of native GLP-1. The review is based on electronic literature searches and legal documents in the form of assessment reports from the European Medicines Agency and the United States Food and Drug Administration. GLP-1-based therapy combines several unique mechanisms of action and have the potential to gain widespread use in the fight against diabetes and obesity. The difference in chemical structure have strong implications for key pharmacokinetic parameters such as absorption and clearance, and eventually the safety and efficacy of the individual GLP-1-RA. The main safety concerns are pancreatitis and neoplasms, for which there are no identifiable differences in risk between the available agents. Antibody formation and injection site reactions are more frequent with the exendin-4-based compounds. The efficacy with regard to Hb(A1c) reduction is superior with the longer-acting agonists, whereas the shorter-acting GLP-1-RA seems to provide greater postprandial glucose control and lower tolerability as a possible consequence of less induction of tachyphylaxis. The future place of these agents will depend on the added safety and efficacy data in the several ongoing cardiovascular outcome trials.

  2. Adverse Effects of GLP-1 Receptor Agonists

    PubMed Central

    Filippatos, Theodosios D.; Panagiotopoulou, Thalia V.; Elisaf, Moses S.

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are a class of injective anti-diabetic drugs that improve glycemic control and many other atherosclerosis-related parameters in patients with type 2 diabetes (T2D). However, the use of this relatively new class of drugs may be associated with certain adverse effects. Concerns have been expressed regarding the effects of these drugs on pancreatic and thyroid tissue, since animal studies and analyses of drug databases indicate an association of GLP-1 receptor agonists with pancreatitis, pancreatic cancer, and thyroid cancer. However, several meta-analyses failed to confirm a cause-effect relation between GLP-1 receptor agonists and the development of these adverse effects. One benefit of GLP-1 receptor agonists is that they do not cause hypoglycemia when combined with metformin or thiazolidinediones, but the dose of concomitant sulphonylurea or insulin may have to be decreased to reduce the risk of hypoglycemic episodes. On the other hand, several case reports have linked the use of these drugs, mainly exenatide, with the occurrence of acute kidney injury, primarily through hemodynamic derangement due to nausea, vomiting, and diarrhea. The most common symptoms associated with the use of GLP-1 receptor agonists are gastrointestinal symptoms, mainly nausea. Other common adverse effects include injection site reactions, headache, and nasopharyngitis, but these effects do not usually result in discontinuation of the drug. Current evidence shows that GLP-1 receptor agonists have no negative effects on the cardiovascular risk of patients with T2D. Thus, GLP-1 receptor agonists appear to have a favorable safety profile, but ongoing trials will further assess their cardiovascular effects. The aim of this review is to analyze critically the available data regarding adverse events of GLP-1 receptor agonists in different anatomic systems published in Pubmed and Scopus. Whenever possible, certain differences between GLP-1

  3. GLP-1 receptor agonists in the treatment of polycystic ovary syndrome.

    PubMed

    Lamos, Elizabeth Mary; Malek, Rana; Davis, Stephen N

    2017-04-01

    Polycystic ovarian syndrome (PCOS) affects many women of child-bearing age and is characterized by hyperandrogenism, ovulatory and metabolic dysfunction. A primary treatment goal is weight reduction. The weight loss effects of glucagon-like peptide-1 receptor agonists (GLP-1RA), previously demonstrated in diabetic and obese non-diabetic patients, offer a unique opportunity to expand the medical options available to PCOS patients. Areas covered: Available clinical trials of glucagon-like peptide-1 receptor agonist therapy in PCOS were reviewed. Literature was searched from PubMed using appropriate search terms up to November 2016. Expert commentary: The available studies of GLP-1 RA therapy in the treatment of excess body weight in women with PCOS demonstrate that exenatide and liraglutide are effective in weight reduction either as monotherapy or in combination with metformin. A few studies showed that androgens may be modestly decreased and menstrual frequency may be increased. Eating behavior may be improved with liraglutide therapy. Glucose parameters are generally improved. GLP-1RAs were well-tolerated, with nausea being the most significant adverse side effect. Barriers to utilization may be the short duration studies, lack of familiarity of the medication, the route of administration (injection) and the variable outcomes on ovulation and hyperandrogenism.

  4. Molecular Mechanisms Underlying the Cardiovascular Benefits of SGLT2i and GLP-1RA.

    PubMed

    Khat, Dorrin Zarrin; Husain, Mansoor

    2018-06-09

    In addition to their effects on glycemic control, two specific classes of relatively new anti-diabetic drugs, namely the sodium glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) have demonstrated reduced rates of major adverse cardiovascular events (MACE) in subjects with type 2 diabetes (T2D) at high risk for cardiovascular disease (CVD). This review summarizes recent experimental results that inform putative molecular mechanisms underlying these benefits. SGLT2i and GLP-1RA exert cardiovascular effects by targeting in both common and distinctive ways (A) several mediators of macro- and microvascular pathophysiology: namely (A1) inflammation and atherogenesis, (A2) oxidative stress-induced endothelial dysfunction, (A3) vascular smooth muscle cell reactive oxygen species (ROS) production and proliferation, and (A4) thrombosis. These agents also exhibit (B) hemodynamic effects through modulation of (B1) natriuresis/diuresis and (B2) the renin-angiotensin-aldosterone system. This review highlights that while GLP-1RA exert direct effects on vascular (endothelial and smooth muscle) cells, the effects of SGLT2i appear to include the activation of signaling pathways that prevent adverse vascular remodeling. Both SGLT2i and GLP-1RA confer hemodynamic effects that counter adverse cardiac remodeling.

  5. Targeting GLP-1 receptor trafficking to improve agonist efficacy.

    PubMed

    Jones, Ben; Buenaventura, Teresa; Kanda, Nisha; Chabosseau, Pauline; Owen, Bryn M; Scott, Rebecca; Goldin, Robert; Angkathunyakul, Napat; Corrêa, Ivan R; Bosco, Domenico; Johnson, Paul R; Piemonti, Lorenzo; Marchetti, Piero; Shapiro, A M James; Cochran, Blake J; Hanyaloglu, Aylin C; Inoue, Asuka; Tan, Tricia; Rutter, Guy A; Tomas, Alejandra; Bloom, Stephen R

    2018-04-23

    Glucagon-like peptide-1 receptor (GLP-1R) activation promotes insulin secretion from pancreatic beta cells, causes weight loss, and is an important pharmacological target in type 2 diabetes (T2D). Like other G protein-coupled receptors, the GLP-1R undergoes agonist-mediated endocytosis, but the functional and therapeutic consequences of modulating GLP-1R endocytic trafficking have not been clearly defined. Here, we investigate a series of biased GLP-1R agonists with variable propensities for GLP-1R internalization and recycling. Compared to a panel of FDA-approved GLP-1 mimetics, compounds that retain GLP-1R at the plasma membrane produce greater long-term insulin release, which is dependent on a reduction in β-arrestin recruitment and faster agonist dissociation rates. Such molecules elicit glycemic benefits in mice without concomitant increases in signs of nausea, a common side effect of GLP-1 therapies. Our study identifies a set of agents with specific GLP-1R trafficking profiles and the potential for greater efficacy and tolerability as T2D treatments.

  6. A review of the new GLP-1 receptor agonist/basal insulin fixed-ratio combination products.

    PubMed

    Nuffer, Wesley; Guesnier, Ashley; Trujillo, Jennifer M

    2018-03-01

    There have been several new treatment approaches established for the management of hyperglycemia in type 2 diabetes (T2D), with treatment guidelines listing both glucagon-like peptide 1 receptor agonists (GLP-1 RAs) and basal insulin therapies as considerations for patients who have failed to control their blood glucose with oral antidiabetic agents. New studies have highlighted the importance of initiating combination therapy earlier in the T2D disease process to avoid clinical inertia and prevent the long-term complications arising from uncontrolled diabetes. Until recently, both GLP-1 RAs and basal insulin therapies were only available as single agents, but there are now two combination pen devices that deliver both a GLP-1 RA and basal insulin simultaneously. This article reviews the current clinical evidence evaluating the use of these combination GLP-1 RA/basal insulin preparations to treat T2D, presents both potential benefits as well as possible downsides with the use of these agents, and discusses the current place in therapy these products represent in the management of T2D.

  7. A comparative safety review between GLP-1 receptor agonists and SGLT2 inhibitors for diabetes treatment.

    PubMed

    Consoli, Agostino; Formoso, Gloria; Baldassarre, Maria Pompea Antonia; Febo, Fabrizio

    2018-03-01

    Glucagon-like peptide-1 receptor agonists (GLP-1RA) and sodium glucose cotransporter 2 inhibitors (SGLT2i) are of particular interest in type 2 diabetes treatment strategies, due to their efficacy in reducing HbA1c with a low risk of hypoglycaemia, to their positive effects on body weight and blood pressure and in light of their effects on cardiovascular risk and on nephroprotection emerged from the most recent cardiovascular outcome trials. Since it is therefore very likely that GLP-1RA and SGLT2i use will become more and more common, it is more and more important to gather and discuss information about their safety profile. Area Covered: adverse events and the safety concerns most often emerged in trials with GLP-1RA namely, exenatide long acting release (LAR), dulaglutide, liraglutide, semaglutide, lixisenatide or SGLT2i, namely empagliflozin, dapagliflozin, canagliflozin and SGLT2i with an attempt at comparing the safety profiles of molecules of these two classes. Expert opinion: GLP-1RA and SGLT2i, although each associated with different specific side effects, share a 'similar' safety profile and are both drugs relatively easy to handle. The potentially complementary mechanisms of action, the cardio and nephroprotective effects demonstrated by molecules of both classes, make these drugs potentially useful even in add on to each other.

  8. Combination therapy with GLP-1 receptor agonists and basal insulin: a systematic review of the literature

    PubMed Central

    Balena, R; Hensley, I E; Miller, S; Barnett, A H

    2013-01-01

    Treatment algorithms for type 2 diabetes call for intensification of therapy over time as the disease progresses and glycaemic control worsens. If diet, exercise and oral antihyperglycaemic medications (OAMs) fail to maintain glycaemic control then basal insulin is added and ultimately prandial insulin may be required. However, such an intensification strategy carries risk of increased hypoglycaemia and weight gain, both of which are associated with worse long-term outcomes. An alternative strategy is to intensify therapy by the addition of a short-acting glucagon-like peptide-1 receptor agonist (GLP-1 RA) rather than prandial insulin. Short-acting GLP-1 RAs such as exenatide twice daily are particularly effective at reducing postprandial glucose while basal insulin has a greater effect on fasting glucose, providing a physiological rationale for this complementary approach. This review analyzes the latest randomized controlled clinical trials of insulin/GLP-1 RA combination therapy and examines results from ‘real-world’ use of the combinations as reported through observational and clinical practice studies. The most common finding across all types of studies was that combination therapy improved glycaemic control without weight gain or an increased risk of hypoglycaemia. Many studies reported weight loss and a reduction in insulin use when a GLP-1 RA was added to existing insulin therapy. Overall, the relative degree of benefit to glycaemic control and weight was influenced by the insulin titration employed in conjunction with the GLP-1 RA. The greatest glycaemic benefits were observed in studies with structured titration of insulin to glycaemic targets while the greatest weight benefits were observed in studies with a protocol-specified focus on insulin sparing. The adverse event profile of GLP-1 RAs in the reviewed trials was similar to that reported with GLP-1 RAs as monotherapy or in combination with OAMs with gastrointestinal events being the most commonly

  9. GLP-1 Receptor Agonists and Cardiovascular Disease in Patients with Type 2 Diabetes

    PubMed Central

    Merino-Torres, Juan Francisco

    2018-01-01

    Diabetes mellitus is a chronic disease prevalence of which is high and continually growing. Cardiovascular disease continues to be the leading cause of death in patients with T2DM. The prevention of cardiovascular complications and the cardiovascular safety of treatments should be a primary objective when selecting treatment. Among all the drugs available, the compounds known as glucagon-like peptide-1 receptor agonists (GLP-1 RAs) appear to be not just innocuous in terms of CVD but indeed to be beneficial. GLP-1 RA actions not only translate on an improvement of well-known cardiovascular risk factors such as glycaemic control, dyslipidaemia, weight, or arterial hypertension but also might show benefits on endothelial function, coronary ischaemia, and heart failure. On the other hand, recent clinical trials aimed at studying cardiovascular episodes have been conducted with GLP-1 RAs. Only liraglutide and semaglutide have shown superiority in cardiovascular benefit compared with placebo. Although many of the mechanisms by which liraglutide and semaglutide produce a cardiovascular benefit are still unknown it would be desirable for these benefits to be incorporated into the therapeutic algorithms routinely used in clinical practice. The purpose of this review is to explore GLP-1 RA actions not only in cardiovascular risk factors (glucose, weight, and hypertension) but also the possible effects on established cardiovascular disease.

  10. [Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

    PubMed

    Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs.

  11. Markers of β-Cell Failure Predict Poor Glycemic Response to GLP-1 Receptor Agonist Therapy in Type 2 Diabetes.

    PubMed

    Jones, Angus G; McDonald, Timothy J; Shields, Beverley M; Hill, Anita V; Hyde, Christopher J; Knight, Bridget A; Hattersley, Andrew T

    2016-02-01

    To assess whether clinical characteristics and simple biomarkers of β-cell failure are associated with individual variation in glycemic response to GLP-1 receptor agonist (GLP-1RA) therapy in patients with type 2 diabetes. We prospectively studied 620 participants with type 2 diabetes and HbA1c ≥58 mmol/mol (7.5%) commencing GLP-1RA therapy as part of their usual diabetes care and assessed response to therapy over 6 months. We assessed the association between baseline clinical measurements associated with β-cell failure and glycemic response (primary outcome HbA1c change 0-6 months) with change in weight (0-6 months) as a secondary outcome using linear regression and ANOVA with adjustment for baseline HbA1c and cotreatment change. Reduced glycemic response to GLP-1RAs was associated with longer duration of diabetes, insulin cotreatment, lower fasting C-peptide, lower postmeal urine C-peptide-to-creatinine ratio, and positive GAD or IA2 islet autoantibodies (P ≤ 0.01 for all). Participants with positive autoantibodies or severe insulin deficiency (fasting C-peptide ≤0.25 nmol/L) had markedly reduced glycemic response to GLP-1RA therapy (autoantibodies, mean HbA1c change -5.2 vs. -15.2 mmol/mol [-0.5 vs. -1.4%], P = 0.005; C-peptide <0.25 nmol/L, mean change -2.1 vs. -15.3 mmol/mol [-0.2 vs. -1.4%], P = 0.002). These markers were predominantly present in insulin-treated participants and were not associated with weight change. Clinical markers of low β-cell function are associated with reduced glycemic response to GLP-1RA therapy. C-peptide and islet autoantibodies represent potential biomarkers for the stratification of GLP-1RA therapy in insulin-treated diabetes. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  12. [Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

    PubMed

    Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

    2014-09-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

  13. Characteristics of patients with type 2 diabetes mellitus newly treated with GLP-1 receptor agonists (CHADIG Study): a cross-sectional multicentre study in Spain

    PubMed Central

    Conget, Ignacio; Mauricio, Dídac; Ortega, Rafael; Detournay, Bruno

    2016-01-01

    Objective Several glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1Ra) have been made recently available in Spain for type 2 diabetes mellitus (DM2) treatment. There are no published data on the clinical and sociodemographic profile of patients initiating treatment with GLP-1Ra in Spain. Our objective was to understand these patients' characteristics in a real-world clinical practice setting. Design Cross-sectional observational study. Setting Spanish specialist outpatient clinics. Participants 403 adults with DM2 initiating GLP-1Ra treatment were included. Primary and secondary outcome measures Sociodemographic and DM2-related clinical data, including treatment at and after GLP-1Ra initiation and comorbidities, were collected. Results Evaluable patients (n=403; 50.9% female) were included (July 2013 to March 2014) at 24 centres by 53 specialists (47 endocrinology, 6 internal medicine), with the following profile (value±SD): age (58.3±10.4 years), diabetes duration (9.9±7 years), body mass index (BMI; 36.2±5.5) and glycated haemoglobin (HbA1c; 8.4±1.4%); 14% had HbA1c≤7%. Previous antidiabetic treatment: 53.8% only oral antidiabetic drugs (OADs), 5.2% insulin and 40% insulin and OAD; of those receiving OAD, 35% single drug, 38.2% 2 drugs and 24% 3 drugs. Concomitant to GLP-1Ra, 55.3% were only on OAD, 36.2% on insulin and OAD, and 7.2% only on insulin. Of those receiving OAD, the GLP-1Ra was mainly associated with 1 drug (65%) or 2 drugs (31.8%). GLP-1Ra are frequently added to existing antidiabetic drugs, with dipeptidyl peptidase-4 inhibitors being the OAD most frequently switched (45% receiving 1 before starting GLP-1Ra, only 2.7% receiving it concomitantly). Conclusions In Spain, GLP-1Ra therapy is usually started in combination with OADs or OADs and insulin. These drugs are used in relatively young patients often not reaching therapeutic goals with other treatment combinations, roughly a decade after diagnosis and with a relatively high BMI

  14. Adding prandial GLP-1 receptor agonists to basal insulin: a promising option for type 2 diabetes therapy.

    PubMed

    Goldenberg, Ronald M; Berard, Lori

    2018-01-01

    Diabetes mellitus is a serious and increasingly prevalent condition in Canada and around the world. Treatment strategies have become increasingly complex, with a widening array of pharmacological agents available for glycemic management in type 2 diabetes mellitus (T2DM). New therapies that act in concert with available basal insulins may represent alternatives to basal insulin intensification with prandial or pre-mixed insulin. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have recently shown promise as useful additions to basal insulin, with significant reductions in glycated hemoglobin and potentially beneficial effects on body weight. This review will focus on pivotal clinical trials to assess the potential benefits of adding prandial GLP-1 RAs to basal insulin in patients with T2DM. Clinical studies combining prandial GLP-1 RAs and basal insulin (published between 2011 and July 2017) were identified and reviewed in PubMed, the Cochrane Central Register of Clinical Trials (Issue 6, June 2017), and clinicaltrials.gov. Most of the studies presented in this review show that the addition of a prandial GLP-1 RA to basal insulin results in equal or slightly superior efficacy compared to the addition of prandial insulin, together with weight loss and less hypoglycemia. The results of the studies suggest that a prandial GLP-1 RA as an add-on to basal insulin may be a safe and effective treatment intensification option (vs basal-plus or basal-bolus insulin).

  15. PSCs and GLP-1R: occurrence in normal pancreas, acute/chronic pancreatitis and effect of their activation by a GLP-1R agonist

    PubMed Central

    Nakamura, Taichi; Ito, Tetsuhide; Uchida, Masahiko; Hijioka, Masayuki; Igarashi, Hisato; Oono, Takamasa; Kato, Masaki; Nakamura, Kazuhiko; Suzuki, Koichi; Jensen, Robert T.; Takayanagi, Ryoichi

    2013-01-01

    Background and Aims There is increasing concern about the development of pancreatitis in patients with diabetes mellitus who received long-term GLP-1 analog treatment. Its pathogenesis is unknown. The effects of GLP-1 agonists on pancreatic endocrine cells is well studied, however there is little information on effects on other pancreatic tissues that might be involved in inflammatory processes. Pancreatic stellate cells (PSCs) can play an important role in pancreatitis, secreting various inflammatory cytokines/chemokines, as well as collagen. In this study, we investigated GLP-1R occurrence in normal pancreas, acute/chronic pancreatitis, and the effects of GLP-1 analog on normal PSCs, their ability to stimulate inflammatory mediator secretion or proliferation. Methods GLP-1R expression/localization in normal pancreas and pancreatitis (acute/chronic) tissues were evaluated with histological/immunohistochemical analysis. PSCs were isolated from male Wistar rats. GLP1R expression and effects of GLP-1 analog on activated PSCs was examined with realtime PCR, MTS assays and Western Blotting. Results In normal pancreas, pancreatic β cells expressed GLP-1R, with only low expression in acinar cells, whereas in acute or chronic pancreatitis, acinar cells, ductal cells and activated PSCs expressed GLP-1R. With activation of normal PSCs, GLP-1R is markedly increased, as is multiple other incretin-related receptors. The GLP-1 analog, liraglutide, did not induce inflammatory genes expression in activated PSCs, but induced proliferation. Liraglutide activated multiple signaling cascades in PSCs, and the ERK pathway mediated the PSCs proliferation. Conclusions GLP-1Rs are expressed in normal pancreas and there is marked enhanced expression in acute/chronic pancreatitis. GLP-1-agonist induced cell proliferation of activated PSCs without increasing release of inflammatory mediators. These results suggest chronic treatment with GLP-1R agonists could lead to proliferation

  16. Characteristics of patients with type 2 diabetes mellitus newly treated with GLP-1 receptor agonists (CHADIG Study): a cross-sectional multicentre study in Spain.

    PubMed

    Conget, Ignacio; Mauricio, Dídac; Ortega, Rafael; Detournay, Bruno

    2016-07-26

    Several glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1Ra) have been made recently available in Spain for type 2 diabetes mellitus (DM2) treatment. There are no published data on the clinical and sociodemographic profile of patients initiating treatment with GLP-1Ra in Spain. Our objective was to understand these patients' characteristics in a real-world clinical practice setting. Cross-sectional observational study. Spanish specialist outpatient clinics. 403 adults with DM2 initiating GLP-1Ra treatment were included. Sociodemographic and DM2-related clinical data, including treatment at and after GLP-1Ra initiation and comorbidities, were collected. Evaluable patients (n=403; 50.9% female) were included (July 2013 to March 2014) at 24 centres by 53 specialists (47 endocrinology, 6 internal medicine), with the following profile (value±SD): age (58.3±10.4 years), diabetes duration (9.9±7 years), body mass index (BMI; 36.2±5.5) and glycated haemoglobin (HbA1c; 8.4±1.4%); 14% had HbA1c≤7%. Previous antidiabetic treatment: 53.8% only oral antidiabetic drugs (OADs), 5.2% insulin and 40% insulin and OAD; of those receiving OAD, 35% single drug, 38.2% 2 drugs and 24% 3 drugs. Concomitant to GLP-1Ra, 55.3% were only on OAD, 36.2% on insulin and OAD, and 7.2% only on insulin. Of those receiving OAD, the GLP-1Ra was mainly associated with 1 drug (65%) or 2 drugs (31.8%). GLP-1Ra are frequently added to existing antidiabetic drugs, with dipeptidyl peptidase-4 inhibitors being the OAD most frequently switched (45% receiving 1 before starting GLP-1Ra, only 2.7% receiving it concomitantly). In Spain, GLP-1Ra therapy is usually started in combination with OADs or OADs and insulin. These drugs are used in relatively young patients often not reaching therapeutic goals with other treatment combinations, roughly a decade after diagnosis and with a relatively high BMI. The latter could be explained by Spanish regional payers limiting reimbursed prescription to

  17. Differences in acute anorectic effects of long-acting GLP-1 receptor agonists in rats.

    PubMed

    Sisley, Stephanie; Smith, Kathleen; Sandoval, Darleen A; Seeley, Randy J

    2014-08-01

    Long-acting glucagon-like peptide-1 receptor (GLP-1R) agonists have both glucose- and weight-lowering effects. The brain is poised to mediate both of these actions since GLP-1Rs are present in key areas known to control weight and glucose. Although some research has been performed on the effects of exendin-4 in the brain, little data exists on the central effects of liraglutide, a long-acting GLP-1R agonist with much closer structural homology to native GLP-1. In lean, Long-Evans rats, we found that direct intra-third cerebroventricular (i3vt) administration of 0.26 nmol liraglutide caused a 50% reduction in food intake. However, exendin-4 produced the same reduction in food intake with 10-fold greater potency (0.02 nmol). These data are supported by similar c-Fos immunoreactivity in the hypothalamic paraventricular nuclei by exendin-4 as compared to liraglutide despite differing doses. The anorectic effects of both drugs were blocked with i3vt pre-treatment of a GLP-1R competitive antagonist, exendin(9-39), indicating that both drugs required the GLP-1R for their effects. Exendin-4, and not liraglutide, caused hyperglycemia when given i3vt prior to an oral glucose tolerance test, although liraglutide did not lower glucose. Thus, these data show that GLP-1R agonists have differing anorectic potencies in the CNS, which may account for some of their clinical differences. Additionally, we show here that the glucose lowering properties of acute administration of GLP-1R agonists are not accounted for by their central effects. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Autocrine selection of a GLP-1R G-protein biased agonist with potent antidiabetic effects.

    PubMed

    Zhang, Hongkai; Sturchler, Emmanuel; Zhu, Jiang; Nieto, Ainhoa; Cistrone, Philip A; Xie, Jia; He, LinLing; Yea, Kyungmoo; Jones, Teresa; Turn, Rachel; Di Stefano, Peter S; Griffin, Patrick R; Dawson, Philip E; McDonald, Patricia H; Lerner, Richard A

    2015-12-01

    Glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) agonists have emerged as treatment options for type 2 diabetes mellitus (T2DM). GLP-1R signals through G-protein-dependent, and G-protein-independent pathways by engaging the scaffold protein β-arrestin; preferential signalling of ligands through one or the other of these branches is known as 'ligand bias'. Here we report the discovery of the potent and selective GLP-1R G-protein-biased agonist, P5. We identified P5 in a high-throughput autocrine-based screening of large combinatorial peptide libraries, and show that P5 promotes G-protein signalling comparable to GLP-1 and Exendin-4, but exhibited a significantly reduced β-arrestin response. Preclinical studies using different mouse models of T2DM demonstrate that P5 is a weak insulin secretagogue. Nevertheless, chronic treatment of diabetic mice with P5 increased adipogenesis, reduced adipose tissue inflammation as well as hepatic steatosis and was more effective at correcting hyperglycaemia and lowering haemoglobin A1c levels than Exendin-4, suggesting that GLP-1R G-protein-biased agonists may provide a novel therapeutic approach to T2DM.

  19. Combination of SGLT-2 inhibitors and GLP-1 receptor agonists: potential benefits in surrogate and hard endpoints.

    PubMed

    Doumas, Michael; Imprialos, Κonstantinos; Stavropoulos, Konstantinos; Reklou, Andromachi; Sachinidis, Alexandros; Athyros, Vasilios G

    2018-06-03

    The treatment of type 2 diabetes mellitus (T2DM) is complex; only few patients successfully attain glycemic targets with monotherapy, most requiring drug combination therapy. The goal of this review was to identify in PubMed the complimentary ways of action leading to clinical benefit (in lowering HbA1c, body weight, renal, and cardiac risk factors and events) of the combination of sodium glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1 RA). SGLT2i, an emerging class of antidiabetic agents with an insulin-independent mechanism of action, are suitable for use in combination with any other class of antidiabetics, including insulin. The use of SGLT2i causes a reduction in cardiovascular disease (CVD) morbidity (mainly heart failure-HF) as well as total and CVD mortality. Besides insulin, SGLT2i may also be combined with incretin-based therapies, such as GLP-1 RA. The later appear to reduce the rate or the progression of both macrovascular (mainly myocardial infarction-MI and stroke) and microvascular complications of DM, having a beneficial effect on all-cause mortality and CVD mortality, as well as CVD events. SGLT2i and GLP-1 RA may have a synergic effect on glucose reduction, weight reduction, renal impairment (both an independent lethal disease and a CVD risk factor) improvement, and cardiac event reduction, because the first reduces HF and related events and the second decreases CVD risk (mainly MI and stroke). Both also reduce total mortality, especially when combined with a statin. The combination of metformin with SGLT2i, GLP-1 RA, and a potent statin, in high CVD risk patients with DM, is expected to substantially reduce CVD mortality and morbidity, improving the quality of life of patients with DM at the same time. Prospective studies are needed to confirm this finding. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  20. Recent Advances in GLP-1 Receptor Agonists for Use in Diabetes Mellitus.

    PubMed

    McBrayer, Dominic N; Tal-Gan, Yftah

    2017-09-01

    Preclinical Research Mimetics of Glucagon-like peptide 1 (GLP-1) represent a useful alternative or complementary treatment choice to insulin in the treatment of diabetes mellitus. The lack of hypoglycemia as a side effect when GLP-1 receptor agonists are used along with the tendency of these therapeutic agents to prevent or even reduce weight gain makes them valuable targets in therapy development. However, native GLP-1 and many of its early analogues have very short half-lives, requiring repeated treatment to maintain therapeutic levels. As all current treatments are injected subcutaneously, a large focus has been made on trying to extend the half-lives of GLP-1 analogues while retaining bioactivity. Most success in this regard has been achieved with the use of peptide-protein fusions, which are not as well suited for oral administration. However, recent work focused on the development of non-fusion peptides with increased half-lives that may be more appropriate for oral administration. This minireview discusses the structural characteristics of past and present analogues as well as the recent work conducted toward developing novel GLP-1 receptor agonists. Drug Dev Res 78 : 292-299, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. The role of basal insulin and GLP-1 receptor agonist combination products in the management of type 2 diabetes

    PubMed Central

    Inman, Taylor R.; Plyushko, Erika; Austin, Nicholas P.; Johnson, Jeremy L.

    2018-01-01

    The prevalence of type 2 diabetes necessitates the development of new treatment options to individualize therapy. Basal insulin has been a standard treatment option for years, while glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have grown in use over the past decade due to glucose-lowering efficacy and weight loss potential. There are two new combination injectable products that have recently been approved combining basal insulins with GLP-1 RAs in single pen-injector devices. United States guidelines recently emphasize the option to use combination injectable therapy with GLP-1 RAs and basal insulin once the basal insulin has been optimally titrated as a second- or third-line agent in addition to metformin without reaching the goal A1c. Insulin glargine/lixisenatide 100/33 (IGlarLixi) can be dosed between 15 and 60 units once daily from a single pen-injector device. Insulin degludec/liraglutide 100/3.6 (IDegLira) can be dosed between 10 and 50 units once daily, also from a single pen-injector device. Maximum doses, while measured in units, correspond to limits defined by each individual GLP-1 RA. The dual use of basal insulin plus GLP-1 RA is non-inferior compared with basal insulin plus a single injection of prandial insulin at the largest meal and compared with twice daily-dosed premixed insulins; and this combination is associated with weight loss and less hypoglycemia. These new combination products could help providers effectively and efficiently follow clinical practice guidelines while enhancing patient adherence with injectable medications. PMID:29796245

  2. The role of basal insulin and GLP-1 receptor agonist combination products in the management of type 2 diabetes.

    PubMed

    Inman, Taylor R; Plyushko, Erika; Austin, Nicholas P; Johnson, Jeremy L

    2018-05-01

    The prevalence of type 2 diabetes necessitates the development of new treatment options to individualize therapy. Basal insulin has been a standard treatment option for years, while glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have grown in use over the past decade due to glucose-lowering efficacy and weight loss potential. There are two new combination injectable products that have recently been approved combining basal insulins with GLP-1 RAs in single pen-injector devices. United States guidelines recently emphasize the option to use combination injectable therapy with GLP-1 RAs and basal insulin once the basal insulin has been optimally titrated as a second- or third-line agent in addition to metformin without reaching the goal A1c. Insulin glargine/lixisenatide 100/33 (IGlarLixi) can be dosed between 15 and 60 units once daily from a single pen-injector device. Insulin degludec/liraglutide 100/3.6 (IDegLira) can be dosed between 10 and 50 units once daily, also from a single pen-injector device. Maximum doses, while measured in units, correspond to limits defined by each individual GLP-1 RA. The dual use of basal insulin plus GLP-1 RA is non-inferior compared with basal insulin plus a single injection of prandial insulin at the largest meal and compared with twice daily-dosed premixed insulins; and this combination is associated with weight loss and less hypoglycemia. These new combination products could help providers effectively and efficiently follow clinical practice guidelines while enhancing patient adherence with injectable medications.

  3. Prediction of thyroid C-cell carcinogenicity after chronic administration of GLP1-R agonists in rodents

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brink, Willem van den; Emerenciana, Annette

    Increased incidence of C-cell carcinogenicity has been observed for glucagon-like-protein-1 receptor (GLP-1r) agonists in rodents. It is suggested that the duration of exposure is an indicator of carcinogenic potential in rodents of the different products on the market. Furthermore, the role of GLP-1-related mechanisms in the induction of C-cell carcinogenicity has gained increased attention by regulatory agencies. This study proposes an integrative pharmacokinetic/pharmacodynamic (PKPD) framework to identify explanatory factors and characterize differences in carcinogenic potential of the GLP-1r agonist products. PK models for four products (exenatide QW (once weekly), exenatide BID (twice daily), liraglutide and lixisenatide) were developed using nonlinearmore » mixed effects modelling. Predicted exposure was subsequently linked to GLP-1r stimulation using in vitro GLP-1r potency data. A logistic regression model was then applied to exenatide QW and liraglutide data to assess the relationship between GLP-1r stimulation and thyroid C-cell hyperplasia incidence as pre-neoplastic predictor of a carcinogenic response. The model showed a significant association between predicted GLP-1r stimulation and C-cell hyperplasia after 2 years of treatment. The predictive performance of the model was evaluated using lixisenatide, for which hyperplasia data were accurately described during the validation step. The use of a model-based approach provided insight into the relationship between C-cell hyperplasia and GLP-1r stimulation for all four products, which is not possible with traditional data analysis methods. It can be concluded that both pharmacokinetics (exposure) and pharmacodynamics (potency for GLP-1r) factors determine C-cell hyperplasia incidence in rodents. Our work highlights the pharmacological basis for GLP-1r agonist-induced C-cell carcinogenicity. The concept is promising for application to other drug classes. - Highlights: • An integrative PKPD model is

  4. Prediction of thyroid C-cell carcinogenicity after chronic administration of GLP1-R agonists in rodents.

    PubMed

    van den Brink, Willem; Emerenciana, Annette; Bellanti, Francesco; Della Pasqua, Oscar; van der Laan, Jan Willem

    2017-04-01

    Increased incidence of C-cell carcinogenicity has been observed for glucagon-like-protein-1 receptor (GLP-1r) agonists in rodents. It is suggested that the duration of exposure is an indicator of carcinogenic potential in rodents of the different products on the market. Furthermore, the role of GLP-1-related mechanisms in the induction of C-cell carcinogenicity has gained increased attention by regulatory agencies. This study proposes an integrative pharmacokinetic/pharmacodynamic (PKPD) framework to identify explanatory factors and characterize differences in carcinogenic potential of the GLP-1r agonist products. PK models for four products (exenatide QW (once weekly), exenatide BID (twice daily), liraglutide and lixisenatide) were developed using nonlinear mixed effects modelling. Predicted exposure was subsequently linked to GLP-1r stimulation using in vitro GLP-1r potency data. A logistic regression model was then applied to exenatide QW and liraglutide data to assess the relationship between GLP-1r stimulation and thyroid C-cell hyperplasia incidence as pre-neoplastic predictor of a carcinogenic response. The model showed a significant association between predicted GLP-1r stimulation and C-cell hyperplasia after 2years of treatment. The predictive performance of the model was evaluated using lixisenatide, for which hyperplasia data were accurately described during the validation step. The use of a model-based approach provided insight into the relationship between C-cell hyperplasia and GLP-1r stimulation for all four products, which is not possible with traditional data analysis methods. It can be concluded that both pharmacokinetics (exposure) and pharmacodynamics (potency for GLP-1r) factors determine C-cell hyperplasia incidence in rodents. Our work highlights the pharmacological basis for GLP-1r agonist-induced C-cell carcinogenicity. The concept is promising for application to other drug classes. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Differences in acute anorectic effects of long-acting GLP-1 receptor agonists in rats

    USDA-ARS?s Scientific Manuscript database

    Long-acting glucagon-like peptide-1 receptor (GLP-1R) agonists have both glucose- and weight-lowering effects. The brain is poised to mediate both of these actions since GLP-1Rs are present in key areas known to control weight and glucose. Although some research has been performed on the effects of ...

  6. Liraglutide Modulates Appetite and Body Weight Via GLP-1R-Expressing Glutamatergic Neurons.

    PubMed

    Adams, Jessica M; Pei, Hongjuan; Sandoval, Darleen A; Seeley, Randy J; Chang, Rui B; Liberles, Stephen D; Olson, David P

    2018-05-18

    Glucagon-like peptide-1 receptor (GLP-1R) agonists are FDA-approved weight loss drugs. Despite their widespread use, the sites of action through which GLP-1R agonists (GLP1RAs) impact appetite and body weight are still not fully understood. Here, we determined whether GLP-1Rs in either GABAergic or glutamatergic neurons are necessary for the acute and chronic effects of the GLP1RA liraglutide on food intake, visceral illness, body weight and neural network activation. We found that mice lacking GLP-1Rs in vGAT -expressing GABAergic neurons responded identically to controls in all parameters measured, whereas deletion of GLP-1Rs in vGlut2 -expressing glutamatergic neurons eliminated liraglutide-induced weight loss and visceral illness and severely attenuated its effects on feeding. Concomitantly, deletion of GLP-1Rs from glutamatergic neurons completely abolished the neural network activation observed after liraglutide administration. We conclude that liraglutide activates a dispersed but discrete neural network to mediate its physiological effects, and that these effects require GLP-1R expression on glutamatergic but not GABAergic neurons. © 2018 by the American Diabetes Association.

  7. Effects of the GLP-1 Agonist Exendin-4 on Intravenous Ethanol Self-Administration in Mice.

    PubMed

    Sørensen, Gunnar; Caine, S Barak; Thomsen, Morgane

    2016-10-01

    Glucagon-like peptide 1 (GLP-1) receptor agonists have been shown to decrease ethanol (EtOH) drinking in rodent assays. The GLP-1 system also powerfully modulates food and fluid intake, gastrointestinal functions, and metabolism. To begin to understand the neurobiological mechanisms by which GLP-1 receptor ligands may be able to control EtOH intake, it is important to ascertain whether they can modulate the direct reinforcing effects of EtOH, without the confound of effects on ingestive behaviors generally. We trained experimentally naïve, free-fed C57BL/6J mice to self-administer EtOH intravenously. Once stable EtOH intake was acquired, we tested the effect of acute pretreatment with the GLP-1 receptor agonist Exendin-4. Effect of Exendin-4 on operant behavior reinforced by a palatable liquid food was similarly evaluated as a control. Intravenous EtOH functioned as a positive reinforcer in over half the mice tested. In mice that acquired self-administration, EtOH intake was high, indeed, reaching toxic doses; 3.2 μg/kg Exendin-4 decreased intravenous EtOH intake by at least 70%, but had no significant effect on food-maintained operant responding. This experiment produced 2 main conclusions. First, although technically challenging and yielding only moderate throughput, the intravenous self-administration procedure in mice is feasible, and sensitive to pharmacological manipulations. Second, GLP-1 receptor agonists can powerfully attenuate voluntary EtOH intake by directly modulating the reinforcing effects of EtOH. These findings support the potential usefulness of GLP-1 receptor ligands in the treatment of alcohol use disorder. Copyright © 2016 by the Research Society on Alcoholism.

  8. Effect of immediate and prolonged GLP-1 receptor agonist administration on uric acid and kidney clearance: Post-hoc analyses of four clinical trials.

    PubMed

    Tonneijck, Lennart; Muskiet, Marcel H A; Smits, Mark M; Bjornstad, Petter; Kramer, Mark H H; Diamant, Michaela; Hoorn, Ewout J; Joles, Jaap A; van Raalte, Daniël H

    2018-05-01

    To determine the effects of glucagon-like peptide (GLP)-1 receptor agonists (RA) on uric acid (UA) levels and kidney UA clearance. This study involved post-hoc analyses of 4 controlled clinical trials, which assessed actions of GLP-1RA administration on kidney physiology. The immediate effects of GLP-1RA exenatide infusion vs placebo were determined in 9 healthy overweight men (Study-A) and in 52 overweight T2DM patients (Study-B). The effects of 12 weeks of long-acting GLP-1RA liraglutide vs placebo in 36 overweight T2DM patients (Study-C) and of 8 weeks of short-acting GLP-1RA lixisenatide vs once-daily titrated insulin glulisine in 35 overweight T2DM patients (Study-D) were also examined. Plasma UA, fractional (inulin-corrected) and absolute urinary excretion of UA (UE UA ) and sodium (UE Na ), and urine pH were determined. Median baseline plasma UA level was 5.39 to 6.33 mg/dL across all studies (17%-22% of subjects were hyperuricaemic). In Study-A, exenatide infusion slightly increased plasma UA (+0.07 ± 0.02 mg/dL, P = .04), and raised absolute-UE UA (+1.58 ± 0.65 mg/min/1.73 m 2 , P = .02), but did not affect fractional UE UA compared to placebo. Fractional UE UA and absolute UE UA correlated with increases in urine pH (r:0.86, P = .003 and r:0.92, P < .001, respectively). Fractional UE UA correlated with increased fractional UE Na (r:0.76, P = .02). In Study-B, exenatide infusion did not affect plasma UA, but increased fractional UE UA (+0.76 ± 0.38%, P = .049) and absolute UE UA (+0.75 ± 0.27 mg/min/1.73 m 2 , P = .007), compared to placebo. In regression analyses, both parameters were explained by changes in urine pH and, in part, by changes in UE Na . In Study-C, liraglutide treatment did not affect plasma UA, UE UA, UE Na or urine pH, compared to placebo. In Study-D, lixisenatide treatment increased UE Na and urine pH from baseline, but did not affect plasma UA or UE UA . Immediate exenatide infusion increases UE UA in overweight healthy men and in

  9. A new angle for glp-1 receptor agonist: the medical economics argument. Editorial on: Huetson P, Palmer JL, Levorsen A, et al. Cost-effectiveness of the once-daily glp-1 receptor agonist lixisenatide compared to bolus insulin both in combination with basal insulin for the treatment of patients with type 2 diabetes in Norway. J Med Econ 2015: 1-13 [Epub ahead of print].

    PubMed

    Valencia, Willy Marcos; Florez, Hermes Jose

    2015-01-01

    Glucagon-like peptide-1 receptor agonists (GLP-1 RA) are relatively new medications for diabetes that offer a weight-loss profile that can be considered desirable for patients with both type 2 diabetes (T2D) and obesity. GLP-1 RA are effective in combination with insulin, and even slightly superior or at least equal to short-acting insulin in T2D; however, since they work in the incretin system, they may not be effective in long-standing disease. Additionally, only recently have publications reported their cardiovascular safety, and there is limited evidence for long-term effectiveness. The work presented by Huetson et al. offers a much needed perspective through a medical economic model for the long term cost-effectiveness of GLP-1 RA. The authors found benefits in quality-adjusted life years and reduced lifetime healthcare costs. While there are a few limitations, this study contributes to the understanding of these agents and their impact on the epidemics of obesity in T2D, where weight management is no longer an option, but an essential component of the diabetes plan of care.

  10. Lowest Glucose Variability and Hypoglycemia Are Observed With the Combination of a GLP-1 Receptor Agonist and Basal Insulin (VARIATION Study).

    PubMed

    Bajaj, Harpreet S; Venn, Karri; Ye, Chenglin; Patrick, Avril; Kalra, Shivani; Khandwala, Hasnain; Aslam, Nadeem; Twum-Barima, David; Aronson, Ronnie

    2017-02-01

    There is a dearth of published literature comparing glucose variability (GV) between different insulin regimens in type 2 diabetes. This cohort study compares GV using continuous glucose monitoring (CGM) in patients with well-controlled type 2 diabetes using four common insulin regimens: basal insulin + oral drugs (BO), basal insulin + glucagon-like peptide 1 receptor agonist (GLP-1 RA) (BGLP), premixed insulin (PM), and basal-bolus insulin (BB). Consecutive patients from three endocrinology clinics who met study criteria-type 2 diabetes, age 18 to 80 years, BMI ≤ 45 kg/m 2 , stable insulin regimen for a minimum of 6 months, and stable A1C value ≤7.5% (58 mmol/mol) before study enrollment-underwent 6-day masked CGM. Hypoglycemia was defined as a sensor glucose concentration <70 mg/dL on CGM. A total of 160 patients with comparable baseline characteristics formed four equal insulin regimen cohorts. The daily glucose SD (the primary outcome) was significantly lower in the BGLP cohort versus the BO, PM, and BB cohorts (P = 0.03, P = 0.01, and P < 0.01, respectively), and remained so after adjusting for age, BMI, type 2 diabetes duration, and A1C. Similarly, daily hypoglycemia outcomes on CGM were least for the BGLP cohort. The lowest GV and lowest hypoglycemia were observed in patients using the combination of basal insulin with a GLP-1 RA, supporting the complementary glycemic action of these agents in type 2 diabetes. These observed benefits in GV and hypoglycemia may contribute to the cardiovascular outcome reduction seen with GLP-1 RA therapy and should be investigated further. © 2017 by the American Diabetes Association.

  11. Use of CRISPR/Cas9-engineered INS-1 pancreatic β cells to define the pharmacology of dual GIPR/GLP-1R agonists.

    PubMed

    Naylor, Jacqueline; Suckow, Arthur T; Seth, Asha; Baker, David J; Sermadiras, Isabelle; Ravn, Peter; Howes, Rob; Li, Jianliang; Snaith, Mike R; Coghlan, Matthew P; Hornigold, David C

    2016-09-15

    Dual-agonist molecules combining glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) activity represent an exciting therapeutic strategy for diabetes treatment. Although challenging due to shared downstream signalling pathways, determining the relative activity of dual agonists at each receptor is essential when developing potential novel therapeutics. The challenge is exacerbated in physiologically relevant cell systems expressing both receptors. To this end, either GIP receptors (GIPR) or GLP-1 receptors (GLP-1R) were ablated via RNA-guided clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 endonucleases in the INS-1 pancreatic β-cell line. Multiple clonal cell lines harbouring gene disruptions for each receptor were isolated and assayed for receptor activity to identify functional knockouts (KOs). cAMP production in response to GIPR or GLP-1R activation was abolished and GIP- or GLP-1-induced potentiation of glucose-stimulated insulin secretion (GSIS) was attenuated in the cognate KO cell lines. The contributions of individual receptors derived from cAMP and GSIS assays were confirmed in vivo using GLP-1R KO mice in combination with a monoclonal antibody antagonist of GIPR. We have successfully applied CRISPR/Cas9-engineered cell lines to determining selectivity and relative potency contributions of dual-agonist molecules targeting receptors with overlapping native expression profiles and downstream signalling pathways. Specifically, we have characterised molecules as biased towards GIPR or GLP-1R, or with relatively balanced potency in a physiologically relevant β-cell system. This demonstrates the broad utility of CRISPR/Cas9 when applied to native expression systems for the development of drugs that target multiple receptors, particularly where the balance of receptor activity is critical. © 2016 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  12. The truncated metabolite GLP-2 (3-33) interacts with the GLP-2 receptor as a partial agonist.

    PubMed

    Thulesen, Jesper; Knudsen, Lotte Bjerre; Hartmann, Bolette; Hastrup, Sven; Kissow, Hannelouise; Jeppesen, Palle Bekker; Ørskov, Cathrine; Holst, Jens Juul; Poulsen, Steen Seier

    2002-01-15

    The therapeutic potential of the intestinotrophic mediator glucagon-like peptide-2 (1-33) [GLP-2 (1-33)] has increased interest in the pharmacokinetics of the peptide. This study was undertaken to investigate whether the primary degradation product GLP-2 (3-33) interacts with the GLP-2 receptor. Functional (cAMP) and binding in vitro studies were carried out in cells expressing the transfected human GLP-2 receptor. Furthermore, a biologic response of GLP-2 (3-33) was tested in vivo. Mice were allocated to groups treated for 10 days (twice daily) with: (1) 5 microg GLP-2 (1-33), (2) 25 microg GLP-2 (3-33), (3) 5 microg GLP-2 (1-33)+100 microg GLP-2 (3-33), or (4) 5 microg GLP-2 (1-33)+500 microg GLP-2 (3-33). The intestine was investigated for growth changes. GLP-2 (3-33) bound to the GLP-2 receptor with a binding affinity of 7.5% of that of GLP-2 (1-33). cAMP accumulation was stimulated with an efficacy of 15% and a potency more than two orders of magnitude lower than that of GLP-2 (1-33). Increasing doses of GLP-2 (3-33) (10(-7)-10(-5) M) caused a shift to the right in the dose-response curve of GLP-2 (1-33). Treatment of mice with either GLP-2 (1-33) or (3-33) induced significant growth responses in both the small and large intestines, but the response induced by GLP-2 (3-33) was much smaller. Co-administration of 500 microg of GLP-2 (3-33) and 5 microg GLP-2 (1-33) resulted in a growth response that was smaller than that of 5 microg GLP-2 (1-33) alone. Consistent with the observed in vivo activities, our functional studies and binding data indicate that GLP-2 (3-33) acts as a partial agonist with potential competitive antagonistic properties on the GLP-2 receptor.

  13. Choosing between GLP-1 Receptor Agonists and DPP-4 Inhibitors: A Pharmacological Perspective

    PubMed Central

    Brown, Dominique Xavier; Evans, Marc

    2012-01-01

    In recent years the incretin therapies have provided a new treatment option for patients with type 2 diabetes mellitus (T2DM). The incretin therapies focus on the increasing levels of the two incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). This results in increased glucose dependent insulin synthesis and release. GLP-1 receptor agonists such as liraglutide and exenatide exert an intrinsic biological effect on GLP-1 receptors directly stimulating the release of insulin from pancreatic beta cells. DPP-4 inhibitors such as sitagliptin and linagliptin prevent the inactivation of endogenous GLP-1 and GIP through competitive inhibition of the DPP-4 enzyme. Both incretin therapies have good safety and tolerability profiles and interact minimally with a number of medications commonly prescribed in T2DM. This paper focuses on the pharmacological basis by which the incretin therapies function and how this knowledge can inform and benefit clinical decisions. Each individual incretin agent has benefits and pitfalls relating to aspects such as glycaemic and nonglycaemic efficacy, safety and tolerability, ease of administration, and cost. Overall, a personalized medicine approach has been found to be favourable, tailoring the incretin agent to benefit and suit patient's needs such as renal impairment (RI) or hepatic impairment (HI). PMID:23125920

  14. Astrocytes Regulate GLP-1 Receptor-Mediated Effects on Energy Balance

    PubMed Central

    Reiner, David J.; Mietlicki-Baase, Elizabeth G.; McGrath, Lauren E.; Zimmer, Derek J.; Bence, Kendra K.; Sousa, Gregory L.; Konanur, Vaibhav R.; Krawczyk, Joanna; Burk, David H.; Kanoski, Scott E.; Hermann, Gerlinda E.; Rogers, Richard C.

    2016-01-01

    Astrocytes are well established modulators of extracellular glutamate, but their direct influence on energy balance-relevant behaviors is largely understudied. As the anorectic effects of glucagon-like peptide-1 receptor (GLP-1R) agonists are partly mediated by central modulation of glutamatergic signaling, we tested the hypothesis that astrocytic GLP-1R signaling regulates energy balance in rats. Central or peripheral administration of a fluorophore-labeled GLP-1R agonist, exendin-4, localizes within astrocytes and neurons in the nucleus tractus solitarius (NTS), a hindbrain nucleus critical for energy balance control. This effect is mediated by GLP-1R, as the uptake of systemically administered fluorophore-tagged exendin-4 was blocked by central pretreatment with the competitive GLP-1R antagonist exendin-(9–39). Ex vivo analyses show prolonged exendin-4-induced activation (live cell calcium signaling) of NTS astrocytes and neurons; these effects are also attenuated by exendin-(9–39), indicating mediation by the GLP-1R. In vitro analyses show that the application of GLP-1R agonists increases cAMP levels in astrocytes. Immunohistochemical analyses reveal that endogenous GLP-1 axons form close synaptic apposition with NTS astrocytes. Finally, pharmacological inhibition of NTS astrocytes attenuates the anorectic and body weight-suppressive effects of intra-NTS GLP-1R activation. Collectively, data demonstrate a role for NTS astrocytic GLP-1R signaling in energy balance control. SIGNIFICANCE STATEMENT Glucagon-like peptide-1 receptor (GLP-1R) agonists reduce food intake and are approved by the Food and Drug Administration for the treatment of obesity, but the cellular mechanisms underlying the anorectic effects of GLP-1 require further investigation. Astrocytes represent a major cellular population in the CNS that regulates neurotransmission, yet the role of astrocytes in mediating energy balance is largely unstudied. The current data provide novel evidence that

  15. Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists in the Treatment of Obese Women with Polycystic Ovary Syndrome.

    PubMed

    Tzotzas, Themistoklis; Karras, Spyridon N; Katsiki, Niki

    2017-01-01

    Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in females and is often associated with a number of cardiometabolic disorders such as central obesity, dyslipidaemia, hypertension, insulin resistance, hyperinsulinaemia, glucose intolerance and type 2 diabetes mellitus (T2DM). Glucagon-like peptide-1 (GLP-1), a gut hormone secreted after a meal, enhances glucosestimulated insulin secretion and additionally suppresses appetite and gastric motility. Most studies found impaired GLP-1 kinetics in obese individuals, whereas small studies in PCOS reported reduced, normal or even elevated GLP-1 levels. Apart from their efficacy in patients with T2DM, some GLP-1 receptor agonists (GLP-1 RAs) have been successfully tested in terms of both efficiency and safety in obese individuals without diabetes and liraglutide 3 mg once daily has been approved as an antiobesity drug in the USA and the European Union. Recently, some small trials of short duration using GLP-1 RAs as monotherapy or combined with metformin in obese PCOS women showed positive results regarding weight reduction and a decrease in testosterone levels but without significant effects on insulin levels, insulin sensitivity and menstrual patterns. Longer term studies with more patients and higher doses of liraglutide (as this drug is already approved for obese individuals) are required to determine the precise indications of GLP-1 RAs in PCOS and to evaluate safety issues. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Rate of Homologous Desensitization and Internalization of the GLP-1 Receptor.

    PubMed

    Shaaban, Ghina; Oriowo, Mabayoje; Al-Sabah, Suleiman

    2016-12-26

    The glucagon-like peptide-1 receptor (GLP-1R) is an important target in the treatment of type 2 diabetes mellitus. The aim of this study was to compare the rate of agonist stimulated desensitization and internalization of GLP-1R. To this end, an N-terminally myc-tagged GLP-1R was stably expressed in HEK-293 cells. Homologous desensitization was assessed by measuring the cAMP response to agonist stimulation following pre-incubation with agonist for up to 120 min. Receptor internalization was monitored using an indirect ELISA-based method and confocal microscopy. Pre-incubation with GLP-1 resulted in a time-dependent loss of response to a second stimulation. Washing cells following pre-incubation failed to bring cAMP levels back to basal. Taking this into account, two desensitization rates were calculated: "apparent" (t 1/2 = 19.27 min) and "net" (t 1/2 = 2.99 min). Incubation of cells with GLP-1 also resulted in a time-dependent loss of receptor cell surface expression (t 1/2 = 2.05 min). Rapid agonist-stimulated internalization of GLP-1R was confirmed using confocal microscopy. Stimulation of GLP-1R with GLP-1 results in rapid desensitization and internalization of the receptor. Interestingly, the rate of "net" desensitization closely matches the rate of internalization. Our results suggest that agonist-bound GLP-1R continues to generate cAMP after it has been internalized.

  17. Regulation of Glucose Homeostasis by GLP-1

    PubMed Central

    Nadkarni, Prashant; Chepurny, Oleg G.; Holz, George G.

    2014-01-01

    Glucagon-like peptide-1(7–36)amide (GLP-1) is a secreted peptide that acts as a key determinant of blood glucose homeostasis by virtue of its abilities to slow gastric emptying, to enhance pancreatic insulin secretion, and to suppress pancreatic glucagon secretion. GLP-1 is secreted from L cells of the gastrointestinal mucosa in response to a meal, and the blood glucose-lowering action of GLP-1 is terminated due to its enzymatic degradation by dipeptidyl-peptidase-IV (DPP-IV). Released GLP-1 activates enteric and autonomic reflexes while also circulating as an incretin hormone to control endocrine pancreas function. The GLP-1 receptor (GLP-1R) is a G protein-coupled receptor that is activated directly or indirectly by blood glucose-lowering agents currently in use for the treatment of type 2 diabetes mellitus (T2DM). These therapeutic agents include GLP-1R agonists (exenatide, liraglutide, lixisenatide, albiglutide, dulaglutide, and langlenatide) and DPP-IV inhibitors (sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin). Investigational agents for use in the treatment of T2DM include GPR119 and GPR40 receptor agonists that stimulate the release of GLP-1 from L cells. Summarized here is the role of GLP-1 to control blood glucose homeo-stasis, with special emphasis on the advantages and limitations of GLP-1-based therapeutics. PMID:24373234

  18. A novel dual GLP-1 and GIP incretin receptor agonist is neuroprotective in a mouse model of Parkinson's disease by reducing chronic inflammation in the brain.

    PubMed

    Cao, Lijun; Li, Dongfang; Feng, Peng; Li, Lin; Xue, Guo-Fang; Li, Guanglai; Hölscher, Christian

    2016-04-13

    The incretins glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are growth factors. GLP-1 mimetics are on the market as treatments for type 2 diabetes. Both GLP-1 and GIP mimetics have shown neuroprotective properties in previous studies. In addition, the GLP-1 mimetic exendin-4 has shown protective effects in a clinical trial in Parkinson's disease (PD) patients. Novel GLP-1/GIP dual-agonist peptides have been developed to treat diabetes. Here, we report the neuroprotective effects of a novel dual agonist (DA-JC1) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. MPTP was injected once daily (20 mg/kg intraperitoneally) for 7 days and the dual agonist was coinjected once daily (50 nmol/kg intraperitoneally). We found that the drug reduced most of the MPTP-induced motor impairments in the rotarod, open-field locomotion, and muscle strength test. The number of tyrosine hydroxylase-positive neurons in the substantia nigra and striatum was reduced by MPTP and increased by DA-JC1. Synapse numbers (synaptophysin expression) were reduced in the substantia nigra and the striatum by MPTP and DA-JC1 reversed this effect. The activation of a chronic inflammation response by MPTP was considerably reduced by the dual agonist (DA) (astroglia and microglia activation). Therefore, dual agonists show promise as a novel treatment of PD.

  19. When Intensive Insulin Therapy (MDI) Fails in Patients With Type 2 Diabetes: Switching to GLP-1 Receptor Agonist Versus Insulin Pump.

    PubMed

    Cohen, Ohad; Filetti, Sebastiano; Castañeda, Javier; Maranghi, Marianna; Glandt, Mariela

    2016-08-01

    Treatment with insulin, alone or with oral or injectable hypoglycemic agents, is becoming increasingly common in patients with type 2 diabetes. However, approximately 40% of patients fail to reach their glycemic targets with the initially prescribed regimen and require intensification of insulin therapy, which increases the risks of weight gain and hypoglycemia. Many of these patients eventually reach a state in which further increases in the insulin dosage fail to improve glycemic control while increasing the risks of weight gain and hypoglycemia. The recently completed OpT2mise clinical trial showed that continuous subcutaneous insulin infusion (CSII) is more effective in reducing glycated hemoglobin (HbA1c) than intensification of multiple daily injection (MDI) insulin therapy in patients with type 2 diabetes who do not respond to intensive insulin therapy. CSII therapy may also be useful in patients who do not reach glycemic targets despite multidrug therapy with basal-bolus insulin and other agents, including glucagon-like peptide (GLP)-1 receptor agonists; current guidelines offer no recommendations for the treatment of such patients. Importantly, insulin and GLP-1 receptor agonists have complementary effects on glycemia and, hence, can be used either sequentially or in combination in the initial management of diabetes. Patients who have not previously failed GLP-1 receptor agonist therapy may show reduction in weight and insulin dose, in addition to moderate improvement in HbA1c, when GLP-1 receptor agonist therapy is added to MDI regimens. In subjects with long-standing type 2 diabetes who do not respond to intensive insulin therapies, switching from MDI to CSII and/or the addition of GLP-1 receptor agonists to MDI have the potential to improve glycemic control without increasing the risk of adverse events. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for

  20. GLP-1 is both anxiogenic and antidepressant; divergent effects of acute and chronic GLP-1 on emotionality.

    PubMed

    Anderberg, Rozita H; Richard, Jennifer E; Hansson, Caroline; Nissbrandt, Hans; Bergquist, Filip; Skibicka, Karolina P

    2016-03-01

    Glucagon-like peptide 1 (GLP-1), produced in the intestine and hindbrain, is known for its glucoregulatory and appetite suppressing effects. GLP-1 agonists are in clinical use for treatment of type 2 diabetes and obesity. GLP-1, however, may also affect brain areas associated with emotionality regulation. Here we aimed to characterize acute and chronic impact of GLP-1 on anxiety and depression-like behavior. Rats were subjected to anxiety and depression behavior tests following acute or chronic intracerebroventricular or intra-dorsal raphe (DR) application of GLP-1 receptor agonists. Serotonin or serotonin-related genes were also measured in the amygdala, DR and the hippocampus. We demonstrate that both GLP-1 and its long lasting analog, Exendin-4, induce anxiety-like behavior in three rodent tests of this behavior: black and white box, elevated plus maze and open field test when acutely administered intraperitoneally, into the lateral ventricle, or directly into the DR. Acute central GLP-1 receptor stimulation also altered serotonin signaling in the amygdala. In contrast, chronic central administration of Exendin-4 did not alter anxiety-like behavior but significantly reduced depression-like behavior in the forced swim test. Importantly, this positive effect of Exendin-4 was not due to significant body weight loss and reduced food intake, since rats pair-fed to Exendin-4 rats did not show altered mood. Collectively we show a striking impact of central GLP-1 on emotionality and the amygdala serotonin signaling that is divergent under acute versus chronic GLP-1 activation conditions. We also find a novel role for the DR GLP-1 receptors in regulation of behavior. These results may have direct relevance to the clinic, and indicate that Exendin-4 may be especially useful for obese patients manifesting with comorbid depression. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. The autonomic nervous system and cardiac GLP-1 receptors control heart rate in mice.

    PubMed

    Baggio, Laurie L; Ussher, John R; McLean, Brent A; Cao, Xiemin; Kabir, M Golam; Mulvihill, Erin E; Mighiu, Alexandra S; Zhang, Hangjun; Ludwig, Andreas; Seeley, Randy J; Heximer, Scott P; Drucker, Daniel J

    2017-11-01

    Glucagon-like peptide-1 (GLP-1) is secreted from enteroendocrine cells and exerts a broad number of metabolic actions through activation of a single GLP-1 receptor (GLP-1R). The cardiovascular actions of GLP-1 have garnered increasing attention as GLP-1R agonists are used to treat human subjects with diabetes and obesity that may be at increased risk for development of heart disease. Here we studied mechanisms linking GLP-1R activation to control of heart rate (HR) in mice. The actions of GLP-1R agonists were examined on the control of HR in wild type mice (WT) and in mice with cardiomyocyte-selective disruption of the GLP-1R (Glp1r CM-/- ). Complimentary studies examined the effects of GLP-1R agonists in mice co-administered propranolol or atropine. The direct effects of GLP-1R agonism on HR and ventricular developed pressure were examined in isolated perfused mouse hearts ex vivo, and atrial depolarization was quantified in mouse hearts following direct application of liraglutide to perfused atrial preparations ex vivo. Doses of liraglutide and lixisenatide that were equipotent for acute glucose control rapidly increased HR in WT and Glp1r CM-/- mice in vivo. The actions of liraglutide to increase HR were more sustained relative to lixisenatide, and diminished in Glp1r CM-/- mice. The acute chronotropic actions of GLP-1R agonists were attenuated by propranolol but not atropine. Neither native GLP-1 nor lixisenatide increased HR or developed pressure in perfused hearts ex vivo. Moreover, liraglutide had no direct effect on sinoatrial node firing rate in mouse atrial preparations ex vivo. Despite co-localization of HCN4 and GLP-1R in primate hearts, HCN4-directed Cre expression did not attenuate levels of Glp1r mRNA transcripts, but did reduce atrial Gcgr expression in the mouse heart. GLP-1R agonists increase HR through multiple mechanisms, including regulation of autonomic nervous system function, and activation of the atrial GLP-1R. Surprisingly, the

  2. Glucagon-Like Peptide-1 Receptor Agonists for the Treatment of Type 2 Diabetes Mellitus: A Position Statement of the Korean Diabetes Association.

    PubMed

    Kim, Hyun Jin; Park, Seok O; Ko, Seung Hyun; Rhee, Sang Youl; Hur, Kyu Yeon; Kim, Nan Hee; Moon, Min Kyong; Lee, Byung Wan; Kim, Jin Hwa; Choi, Kyung Mook

    2017-12-01

    The glucagon-like peptide-1 receptor agonists (GLP-1RAs) were recommended as a monotherapy or combination therapy with oral hypoglycemic agents or basal insulin in the position statement of the Korean Diabetes Association 2017 for pharmacological therapy. Many randomized clinical trials and systematic reviews report that GLP-1RAs have considerable glucose-lowering effect and lead to weight reduction and low risk of hypoglycemia when used as a monotherapy or combination therapy. The cardiovascular safety of GLP-1RAs has been assessed in several randomized clinical trials and systematic reviews. The results of cardiovascular outcome trials of long-acting GLP-1RAs (liraglutide, semaglutide) demonstrated cardiovascular benefits in subjects with type 2 diabetes mellitus and a high risk of cardiovascular disease. The GLP-1RA may be a choice of therapy when weight control and avoidance of hypoglycemia are important, and patients with high risk of cardiovascular disease might also favor choosing GLP-1RA. Copyright © 2017 Korean Diabetes Association.

  3. Glucagon-like peptide-1 receptor agonists favorably address all components of metabolic syndrome.

    PubMed

    Chatterjee, Sanjay; Ghosal, Samit; Chatterjee, Saurav

    2016-10-15

    Cardiovascular death is the leading cause of mortality for patients with type 2 diabetes mellitus. The etiology of cardiovascular disease in diabetes may be divided into hyperglycemia per se and factors operating through components of metabolic syndrome (MetS). Hyperglycemia causes direct injury to vascular endothelium and possibly on cardiac myocytes. MetS is a cluster of risk factors like obesity, hyperglycemia, hypertension and dyslipidemia. The incidence of this syndrome is rising globally. Glucagon-like peptide-1 receptor agonists (GLP-1RA) are a group of drugs, which address all components of this syndrome favorably. Experimental evidence suggests that they have favorable actions on myocardium as well. Several compounds belonging to GLP-1RA class are in market now and a large number awaiting their entry. Although, originally this class of drugs emerged as a treatment for type 2 diabetes mellitus, more recent data generated revealed beneficial effects on multiple metabolic parameters. We have studied literature published between 2000 and 2016 to look into effects of GLP-1RA on components of MetS. Results from recently concluded clinical trials suggest that some of the molecules in this class may have favorable effects on cardiovascular outcome.

  4. Pulmonary delivery of a GLP-1 receptor agonist, BMS-686117.

    PubMed

    Qian, Feng; Mathias, Neil; Moench, Paul; Chi, Cecilia; Desikan, Sridhar; Hussain, Munir; Smith, Ronald L

    2009-01-21

    Alternate delivery route of therapeutic peptides is an attractive non-invasive option to patients who must chronically self-administer their medication through injections. In recent years, much attention has centered on pulmonary peptide delivery of peptide drugs such as insulin and GLP-1 mimetic peptides in the treatment of type II diabetes. In this study, we assessed the feasibility of delivering BMS-686117, an 11-mer GLP-1 receptor peptide agonist, to the lung in rats via intratracheal administration. The pharmacokinetic profiles of three spray-dried, prototype inhaled powder formulations, 80/20 BMS-686117/trehalose (I), 100% BMS-686117 (II), and 20/80 BMS-686117/mannitol (III), as well as a lyophilized BMS-686117 powder, were compared with intravenously and subcutaneously administered peptide. The spray-dried formulations were mostly spherical particles with narrow particle size distribution between 2 to 10 microm, which are better suited for inhalation delivery than the lyophilized, irregular shape powder with a wide particle size distribution between 2 to 100 microm. Prototype III exhibited the best physical characteristics and in vivo performance, with bioavailability of 45% relative to subcutaneous administration. The T(max) for lung delivered peptide formulations were almost twice as fast as subcutaneous injection, suggesting potential for rapid absorption and onset of action. This study demonstrated that pulmonary delivery is a promising, non-invasive route for the administration of BMS-686117.

  5. HBA1C CONTROL AND COST-EFFECTIVENESS IN PATIENTS WITH TYPE 2 DIABETES MELLITUS INITIATED ON CANAGLIFLOZIN OR A GLUCAGON-LIKE PEPTIDE 1 RECEPTOR AGONIST IN A REAL-WORLD SETTING.

    PubMed

    Wysham, Carol H; Pilon, Dominic; Ingham, Mike; Lafeuille, Marie-Hélène; Emond, Bruno; Kamstra, Rhiannon; Pfeifer, Michael; Lefebvre, Patrick

    2018-03-01

    To compare glycated hemoglobin (HbA1c) control and medication costs between patients with type 2 diabetes mellitus (T2DM) treated with canagliflozin 300 mg (CANA) or a glucagon-like peptide 1 receptor agonist (GLP-1 RA) in a real-world setting. Adults with T2DM newly initiated on CANA or a GLP-1 RA (index date) were identified from IQVIA ™ Real-World Data Electronic Medical Records U.S. database (March 29, 2012-April 30, 2016). Inverse probability of treatment weighting accounted for differences in baseline characteristics. HbA1c levels at 3-month intervals were compared using generalized estimating equations. Medication costs used wholesale acquisition costs. For both cohorts (CANA: n = 11,435; GLP-1 RA: n = 11,582), HbA1c levels decreased at 3 months postindex and remained lower through 30 months. Absolute changes in mean HbA1c from index to 3 months postindex for CANA and GLP-1 RA were -1.16% and -1.21% (patients with baseline HbA1c ≥7% [53 mmol/mol]); -1.54% and -1.51% (patients with baseline HbA1c ≥8% [64 mmol/mol]); and -2.13% and -1.99% (patients with baseline HbA1c ≥9% [75 mmol/mol]), respectively. Postindex, CANA patients with baseline HbA1c ≥7% had similar HbA1c levels at each interval versus GLP-1 RA patients, except 9 months (mean HbA1c, 7.75% [61 mmol/mol] vs. 7.86% [62 mmol/mol]; P = .0305). CANA patients with baseline HbA1c ≥8% and ≥9% had consistently lower HbA1c numerically versus GLP-1 RA patients and statistically lower HbA1c at 9 (baseline HbA1c ≥8% or ≥9%), 27, and 30 months (baseline HbA1c ≥9%). Continuous 12-month medication cost $3,326 less for CANA versus GLP-1 RA. This retrospective study demonstrated a similar evolution of HbA1c levels among CANA and GLP-1 RA patients in a real-world setting. Lower medication costs suggest CANA is economically dominant over GLP-1 RA (similar effectiveness, lower cost). AHA = antihyperglycemic agent BMI = body mass index CANA = canagliflozin 300 mg DCSI = diabetes complications severity

  6. Small-molecule agonists for the glucagon-like peptide 1 receptor

    PubMed Central

    Knudsen, Lotte Bjerre; Kiel, Dan; Teng, Min; Behrens, Carsten; Bhumralkar, Dilip; Kodra, János T.; Holst, Jens J.; Jeppesen, Claus B.; Johnson, Michael D.; de Jong, Johannes Cornelis; Jorgensen, Anker Steen; Kercher, Tim; Kostrowicki, Jarek; Madsen, Peter; Olesen, Preben H.; Petersen, Jacob S.; Poulsen, Fritz; Sidelmann, Ulla G.; Sturis, Jeppe; Truesdale, Larry; May, John; Lau, Jesper

    2007-01-01

    The peptide hormone glucagon-like peptide (GLP)-1 has important actions resulting in glucose lowering along with weight loss in patients with type 2 diabetes. As a peptide hormone, GLP-1 has to be administered by injection. Only a few small-molecule agonists to peptide hormone receptors have been described and none in the B family of the G protein coupled receptors to which the GLP-1 receptor belongs. We have discovered a series of small molecules known as ago-allosteric modulators selective for the human GLP-1 receptor. These compounds act as both allosteric activators of the receptor and independent agonists. Potency of GLP-1 was not changed by the allosteric agonists, but affinity of GLP-1 for the receptor was increased. The most potent compound identified stimulates glucose-dependent insulin release from normal mouse islets but, importantly, not from GLP-1 receptor knockout mice. Also, the compound stimulates insulin release from perfused rat pancreas in a manner additive with GLP-1 itself. These compounds may lead to the identification or design of orally active GLP-1 agonists. PMID:17213325

  7. Chronic administration of Glucagon-like peptide-1 receptor agonists improves trabecular bone mass and architecture in ovariectomised mice.

    PubMed

    Pereira, M; Jeyabalan, J; Jørgensen, C S; Hopkinson, M; Al-Jazzar, A; Roux, J P; Chavassieux, P; Orriss, I R; Cleasby, M E; Chenu, C

    2015-12-01

    Some anti-diabetic therapies can have adverse effects on bone health and increase fracture risk. In this study, we tested the skeletal effects of chronic administration of two Glucagon-like peptide-1 receptor agonists (GLP-1RA), increasingly used for type 2 diabetes treatment, in a model of osteoporosis associated bone loss and examined the expression and activation of GLP-1R in bone cells. Mice were ovariectomised (OVX) to induce bone loss and four weeks later they were treated with Liraglutide (LIR) 0.3mg/kg/day, Exenatide (Ex-4) 10 μg/kg/day or saline for four weeks. Mice were injected with calcein and alizarin red prior to euthanasia, to label bone-mineralising surfaces. Tibial micro-architecture was determined by micro-CT and bone formation and resorption parameters measured by histomorphometric analysis. Serum was collected to measure calcitonin and sclerostin levels, inhibitors of bone resorption and formation, respectively. GLP-1R mRNA and protein expression were evaluated in the bone, bone marrow and bone cells using RT-PCR and immunohistochemistry. Primary osteoclasts and osteoblasts were cultured to evaluate the effect of GLP-1RA on bone resorption and formation in vitro. GLP-1RA significantly increased trabecular bone mass, connectivity and structure parameters but had no effect on cortical bone. There was no effect of GLP-1RA on bone formation in vivo but an increase in osteoclast number and osteoclast surfaces was observed with Ex-4. GLP-1R was expressed in bone marrow cells, primary osteoclasts and osteoblasts and in late osteocytic cell line. Both Ex-4 and LIR stimulated osteoclastic differentiation in vitro but slightly reduced the area resorbed per osteoclast. They had no effect on bone nodule formation in vitro. Serum calcitonin levels were increased and sclerostin levels decreased by Ex-4 but not by LIR. Thus, GLP-1RA can have beneficial effects on bone and the expression of GLP-1R in bone cells may imply that these effects are exerted directly

  8. The cardiovascular safety trials of DPP-4 inhibitors, GLP-1 agonists, and SGLT2 inhibitors.

    PubMed

    Secrest, Matthew H; Udell, Jacob A; Filion, Kristian B

    2017-04-01

    In this paper, we review the results of large, double-blind, placebo-controlled randomized trials mandated by the US Food and Drug Administration to examine the cardiovascular safety of newly-approved antihyperglycemic agents in patients with type 2 diabetes. The cardiovascular effects of dipeptidyl peptidase-4 (DPP-4) inhibitors remain controversial: while these drugs did not reduce or increase the risk of primary, pre-specified composite cardiovascular outcomes, one DPP-4 inhibitor (saxagliptin) increased the risk of hospitalization for heart failure in the overall population; another (alogliptin) demonstrated inconsistent effects on heart failure hospitalization across subgroups of patients, and a third (sitagliptin) demonstrated no effect on heart failure. Evidence for cardiovascular benefits of glucagon-like peptide-1 (GLP-1) agonists has been similarly heterogeneous, with liraglutide and semaglutide reducing the risk of composite cardiovascular outcomes, but lixisenatide having no reduction or increase in cardiovascular risk. The effect of GLP-1 agonists on retinopathy remains a potential concern. In the only completed trial to date to assess a sodium-glucose cotransporter-2 (SGLT2) inhibitor, empagliflozin reduced the risk of composite cardiovascular endpoints, predominantly through its impact on cardiovascular mortality and heart failure hospitalization. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Use of glucagon-like peptide-1 receptor agonists and bone fractures: a meta-analysis of randomized clinical trials.

    PubMed

    Mabilleau, Guillaume; Mieczkowska, Aleksandra; Chappard, Daniel

    2014-05-01

    Patients with type 2 diabetes mellitus (T2DM) are at a higher risk of bone fractures independent of the use of antidiabetic medications. Furthermore, antidiabetic medications could directly affect bone metabolism. Recently, the use of dipeptidyl peptidase-4 inhibitors has been associated with a lower rate of bone fracture. The aim of the present meta-analysis was to assess whether patients with T2DM treated with glucagon-like peptide-1 receptor agonists (GLP-1Ra) present a lower incidence of bone fracture compared with patients using other antidiabetic drugs. A search on Medline, Embase, and http://www.clinicaltrials.gov, as well as a manual search for randomized clinical trials of T2DM treated with either a GLP-1Ra or another antidiabetic drug for a duration of ≥24 weeks was conducted by two authors (GM, AM) independently. Although 28 eligible studies were identified, only seven trials reported the occurrence of at least a bone fracture in one arm of the trial. The total number of fractures was 19 (13 and six with GLP-1Ra and comparator, respectively). The pooled Mantel-Haenszel odds ratio for GLP-1Ra was 0.75 (95% confidence interval 0.28-2.02, P = 0.569) in trials versus other antidiabetic agents. Although preliminary, our study highlighted that the use of GLP-1Ra does not modify the risk of bone fracture in T2DM compared with the use of other antidiabetic medications. © 2013 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

  10. Activation of GLP-1 Receptor Promotes Bone Marrow Stromal Cell Osteogenic Differentiation through β-Catenin

    PubMed Central

    Meng, Jingru; Ma, Xue; Wang, Ning; Jia, Min; Bi, Long; Wang, Yunying; Li, Mingkai; Zhang, Huinan; Xue, Xiaoyan; Hou, Zheng; Zhou, Ying; Yu, Zhibin; He, Gonghao; Luo, Xiaoxing

    2016-01-01

    Summary Glucagon-like peptide 1 (GLP-1) plays an important role in regulating bone remodeling, and GLP-1 receptor agonist shows a positive relationship with osteoblast activity. However, GLP-1 receptor is not found in osteoblast, and the mechanism of GLP-1 receptor agonist on regulating bone remodeling is unclear. Here, we show that the GLP-1 receptor agonist exendin-4 (Ex-4) promoted bone formation and increased bone mass and quality in a rat unloading-induced bone loss model. These functions were accompanied by an increase in osteoblast number and serum bone formation markers, while the adipocyte number was decreased. Furthermore, GLP-1 receptor was detected in bone marrow stromal cells (BMSCs), but not in osteoblast. Activation of GLP-1 receptor by Ex-4 promoted the osteogenic differentiation and inhibited BMSC adipogenic differentiation through regulating PKA/β-catenin and PKA/PI3K/AKT/GSK3β signaling. These findings reveal that GLP-1 receptor regulates BMSC osteogenic differentiation and provide a molecular basis for therapeutic potential of GLP-1 against osteoporosis. PMID:26947974

  11. A novel GLP-1/GIP dual agonist is more effective than liraglutide in reducing inflammation and enhancing GDNF release in the MPTP mouse model of Parkinson's disease.

    PubMed

    Yuan, Ziyue; Li, Dongfang; Feng, Peng; Xue, Guofang; Ji, Chenhui; Li, Guanglai; Hölscher, Christian

    2017-10-05

    Type 2 diabetes mellitus (T2DM) is one of the risk factors for Parkinson's disease (PD). Insulin desensitisation has been observed in the brains of patients, which may promote neurodegeneration. Incretins are a family of growth factors that can re-sensitise insulin signalling. We have previously shown that mimetics of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropypridine (MPTP) mouse model of PD. Recently, dual GLP-1/GIP receptor agonists have been developed. We therefore tested the novel dual agonist DA3-CH in comparison with the best GLP-1 analogue currently on the market, liraglutide (both drugs 25nmol/kg ip once-daily for 7 days) in the MPTP mouse model of PD (25mg/kg ip once-daily for 7 days). In the Rotarod and grip strength assessment, DA3-CH was superior to liraglutide in reversing the MPTP-induced motor impairment. Dopamine synthesis as indicated by levels of tyrosine hydroxylase was much reduced by MPTP in the substantia nigra and striatum, and DA3-CH reversed this while liragutide only partially reversed this. The chronic inflammation response as shown in increased levels of activated microglia and astrocytes was reduced by both drugs. Importantly, expression levels of the neuroprotective growth factor Glial Derived Neurotrophic Factor (GDNF) was much enhanced by both DA3-CH and liragutide. The results demonstrate that the combination of GLP-1 and GIP receptor activation is superior to single GLP-1 receptor activation alone. Therefore, new dual agonists may be a promising treatment for PD. The GLP-1 receptor agonist exendin-4 has already shown disease modifying effects in clinical trials in PD patients. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Addition of or switch to insulin therapy in people treated with glucagon-like peptide-1 receptor agonists: A real-world study in 66 583 patients.

    PubMed

    Montvida, Olga; Klein, Kerenaftali; Kumar, Sudhesh; Khunti, Kamlesh; Paul, Sanjoy K

    2017-01-01

    Real world outcomes of addition or switch to insulin therapy in type 2 diabetes (T2DM) patients on glucagon-like paptide-1 receptor agonist (GLP-1RA) with inadequately controlled hyperglycaemia, are not known. Patients with T2DM (n = 66 583) with a minimum of 6 months of GLP-1RA treatment and without previous insulin treatment were selected. Those who added insulin (n = 39 599) or switched to insulin after GLP-1RA cessation (n = 4706) were identified. Adjusted changes in glycated haemoglobin (HbA1c), weight, systolic blood pressure (SBP), and LDL cholesterol were estimated over 24 months follow-up. Among those who continued with GLP-1RA treatment without adding or switching to insulin, the highest adjusted mean HbA1c change was achieved within 6 months, with no further glycaemic benefits observed during 24 months of follow-up. Addition of insulin within 6 months of GLP-1RA initiation was associated with 18% higher odds of achieving HbA1c <7% at 24 months, compared with adding insulin later. At 24 months, those who added insulin reduced HbA1c significantly by 0.55%, while no glycaemic benefit was observed in those who switched to insulin. Irrespective of intensification with insulin, weight, SBP and LDL cholesterol were significantly reduced by 3 kg, 3 mm Hg, and 0.2 mmol/L, respectively, over 24 months. Significant delay in intensification of treatment by addition of insulin is observed in patients with T2DM inadequately controlled with GLP-1RA. Earlier addition of insulin is associated with better glycaemic control, while switching to insulin is not clinically beneficial during 2 years of treatment. Non-responding patients on GLP-1RA would benefit from adding insulin therapy, rather than switching to insulin. © 2016 John Wiley & Sons Ltd.

  13. A novel dual GLP-1 and GIP receptor agonist is neuroprotective in the MPTP mouse model of Parkinson's disease by increasing expression of BNDF.

    PubMed

    Ji, Chenhui; Xue, Guo-Fang; Lijun, Cao; Feng, Peng; Li, Dongfang; Li, Lin; Li, Guanglai; Hölscher, Christian

    2016-03-01

    The incretins glucagon-like peptide 1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) are growth factors with neuroprotective properties. GLP-1 mimetics are on the market as treatments for type 2 diabetes and are well tolerated. Both GLP-1 and GIP mimetics have shown neuroprotective properties in animal models of Parkinson's and Alzheimer's disease. In addition, the GLP-1 mimetic exendin-4 has shown protective effects in a clinical trial in Parkinson's disease (PD) patients. Novel GLP-1/GIP dual-agonist peptides have been developed and are tested in diabetic patients. Here we demonstrate the neuroprotective effects of a novel dual agonist (DA-JC1) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. MPTP was injected once-daily (20 mg/kg i.p.) for 7 days, and the dual agonist was injected 30 min later i.p. (50 nmol/kg bw). The PI3k inhibitor LY294002 (0.6 mg/kg i.v.) was co-injected in one group. DA-JC1 reduced or reversed most of the MPTP induced motor impairments in the rotarod and in a muscle strength test. The number of tyrosine hydroxylase (TH) positive neurons in the substantia nigra (SN) was reduced by MPTP and increased by DA-JC1. The ratio of anti-inflammatory Bcl-2 to pro-inflammatory BAX as well as the activation of the growth factor kinase Akt was reduced by MPTP and reversed by DA-JC1. The PI3k inhibitor had only limited effect on the DA-JC1 drug effect. Importantly, levels of the neuroprotective brain derived neurotropic factor (BDNF) were reduced by MPTP and enhanced by DA-JC1. The results demonstrate that DA-JC1 shows promise as a novel treatment for PD. Copyright © 2016. Published by Elsevier B.V.

  14. Characterization of signal bias at the GLP-1 receptor induced by backbone modification of GLP-1.

    PubMed

    Hager, Marlies V; Clydesdale, Lachlan; Gellman, Samuel H; Sexton, Patrick M; Wootten, Denise

    2017-07-15

    The glucagon-like peptide-1 receptor (GLP-1R) is a class B G protein-coupled receptor that is a major therapeutic target for the treatment of type 2 diabetes. Activation of this receptor promotes insulin secretion and blood glucose regulation. The GLP-1R can initiate signaling through several intracellular pathways upon activation by GLP-1. GLP-1R ligands that preferentially stimulate subsets among the natural signaling pathways ("biased agonists") could be useful as tools for elucidating the consequences of specific pathways and might engender therapeutic agents with tailored effects. Using HEK-293 cells recombinantly expressing human GLP-1R, we have previously reported that backbone modification of GLP-1, via replacement of selected α-amino acid residues with β-amino acid residues, generates GLP-1 analogues with distinctive preferences for promoting G protein activation versus β-arrestin recruitment. Here, we have explored the influence of cell background across these two parameters and expanded our analysis to include affinity and other key signaling pathways (intracellular calcium mobilization and ERK phosphorylation) using recombinant human GLP-1R expressed in a CHO cell background, which has been used extensively to demonstrate biased agonism of GLP-1R ligands. The new data indicate that α/β-peptide analogues of GLP-1 exhibit a range of distinct bias profiles relative to GLP-1 and that broad assessment of signaling endpoints is required to reveal the spectrum of behavior of modified peptides. These results support the view that backbone modification via α→β amino acid replacement can enable rapid discovery of peptide hormone analogues that display substantial signal bias at a cognate GPCR. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. GLP-1 agonism stimulates brown adipose tissue thermogenesis and browning through hypothalamic AMPK.

    PubMed

    Beiroa, Daniel; Imbernon, Monica; Gallego, Rosalía; Senra, Ana; Herranz, Daniel; Villarroya, Francesc; Serrano, Manuel; Fernø, Johan; Salvador, Javier; Escalada, Javier; Dieguez, Carlos; Lopez, Miguel; Frühbeck, Gema; Nogueiras, Ruben

    2014-10-01

    GLP-1 receptor (GLP-1R) is widely located throughout the brain, but the precise molecular mechanisms mediating the actions of GLP-1 and its long-acting analogs on adipose tissue as well as the brain areas responsible for these interactions remain largely unknown. We found that central injection of a clinically used GLP-1R agonist, liraglutide, in mice stimulates brown adipose tissue (BAT) thermogenesis and adipocyte browning independent of nutrient intake. The mechanism controlling these actions is located in the hypothalamic ventromedial nucleus (VMH), and the activation of AMPK in this area is sufficient to blunt both central liraglutide-induced thermogenesis and adipocyte browning. The decreased body weight caused by the central injection of liraglutide in other hypothalamic sites was sufficiently explained by the suppression of food intake. In a longitudinal study involving obese type 2 diabetic patients treated for 1 year with GLP-1R agonists, both exenatide and liraglutide increased energy expenditure. Although the results do not exclude the possibility that extrahypothalamic areas are also modulating the effects of GLP-1R agonists, the data indicate that long-acting GLP-1R agonists influence body weight by regulating either food intake or energy expenditure through various hypothalamic sites and that these mechanisms might be clinically relevant. © 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  16. Ipragliflozin Add-on Therapy to a GLP-1 Receptor Agonist in Japanese Patients with Type 2 Diabetes (AGATE): A 52-Week Open-Label Study.

    PubMed

    Ishihara, Hisamitsu; Yamaguchi, Susumu; Nakao, Ikko; Sakatani, Taishi

    2018-06-20

    Few data are available regarding ipragliflozin treatment in combination with glucagon-like peptide-1 (GLP-1) receptor agonists. The aim of this study was to evaluate the efficacy and safety of ipragliflozin in combination with GLP-1 receptor agonists in Japanese patients with inadequately controlled type 2 diabetes mellitus (T2DM). This multicenter study (consisting of three periods: a 4-week washout period, a 6-week observation period, and a 52-week open-label treatment period) included patients aged ≥ 20 years who received a stable dose/regimen of a GLP-1 receptor agonist either solely or in combination therapy with a sulfonylurea for ≥ 6 weeks, with glycosylated hemoglobin (HbA1c) of ≥ 7.5% and a fasting plasma glucose (FPG) of ≥ 126 mg/dL. Ipragliflozin treatment was given at a fixed dose of 50 mg/day for 20 weeks, followed by 50 or 100 mg/day for 32 weeks. Changes from baseline in glycemic control and other parameters were examined; safety was also assessed. The mean changes in HbA1c and body weight from baseline to end of treatment were - 0.92% and - 2.69 kg, respectively, in all ipragliflozin-treated patients (n = 103). Overall, sustained reductions from baseline were observed for HbA1c, FPG, self-monitored blood glucose, and body weight during the 52-week treatment. The dose increase of ipragliflozin to 100 mg/day resulted in better glycemic control and weight reduction for patients in whom the 50-mg dose was insufficient. Overall, 46.6% (48/103) of patients experienced drug-related adverse events. The most common drug-related treatment-emergent adverse events were pollakiuria (9.7%), hypoglycemia (8.7%), constipation (6.8%), and thirst (5.8%). Combined therapy with ipragliflozin and GLP-1 receptor agonists/sulfonylureas was significantly efficacious in reducing glycemic parameters in patients with T2DM with inadequate glycemic control, and no major safety concerns were identified. The results from this study suggest

  17. Effect of GLP-1 receptor agonist treatment on body weight in obese antipsychotic-treated patients with schizophrenia: a randomized, placebo-controlled trial.

    PubMed

    Ishøy, Pelle L; Knop, Filip K; Broberg, Brian V; Bak, Nikolaj; Andersen, Ulrik B; Jørgensen, Niklas R; Holst, Jens J; Glenthøj, Birte Y; Ebdrup, Bjørn H

    2017-02-01

    Schizophrenia is associated with cardiovascular co-morbidity and a reduced life-expectancy of up to 20 years. Antipsychotics are dopamine D 2 receptor antagonists and are the standard of medical care in schizophrenia, but the drugs are associated with severe metabolic side effects such as obesity and diabetes. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are registered for treatment of both obesity and type 2 diabetes. We investigated metabolic effects of the GLP-1RA, exenatide once-weekly, in non-diabetic, antipsychotic-treated, obese patients with schizophrenia. Antipsychotic-treated, obese, non-diabetic, schizophrenia spectrum patients were randomized to double-blinded adjunctive treatment with once-weekly subcutaneous exenatide (n = 23) or placebo (n = 22) injections for 3 months. The primary outcome was loss of body weight after treatment and repeated measures analysis of variance was used as statistical analysis. Between March 2013 and June 2015, 40 patients completed the trial. At baseline, mean body weight was 118.3 ± 16.0 kg in the exenatide group and 111.7 ± 18.0 kg in the placebo group, with no group differences ( P = .23). The exenatide and placebo groups experienced significant ( P = .004), however similar ( P = .98), weight losses of 2.24 ± 3.3 and 2.23 ± 4.4 kg, respectively, after 3 months of treatment. Treatment with exenatide once-weekly did not promote weight loss in obese, antipsychotic-treated patients with schizophrenia compared to placebo. Our results could suggest that the body weight-lowering effect of GLP-1RAs involves dopaminergic signaling, but blockade of other receptor systems may also play a role. Nevertheless, anti-obesity regimens effective in the general population may not be readily implemented in antipsychotic-treated patients with schizophrenia. © 2016 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.

  18. Preoperative weight loss with glucagon-like peptide-1 receptor agonist treatment predicts greater weight loss achieved by the combination of medical weight management and bariatric surgery in patients with type 2 diabetes: A longitudinal analysis.

    PubMed

    Tang, Tien; Abbott, Sally; le Roux, Carel W; Wilson, Violet; Singhal, Rishi; Bellary, Srikanth; Tahrani, Abd A

    2018-03-01

    We examined the relationship between weight changes after preoperative glucagon-like peptide-1 receptor agonist (GLP-1RA) treatment and weight changes from the start of medical weight management (MWM) until 12 months after bariatric surgery in patients with type 2 diabetes in a retrospective cohort study. A total of 45 patients (64.4% women, median [interquartile range] age 49 [45-60] years) were included. The median (interquartile range) weight loss from start of MWM until 12 months post-surgery was 17.9% (13.0%-29.3%). GLP-1RA treatment during MWM resulted in 5.0% (1.9%-7.7%) weight loss. Weight loss during GLP-1RA treatment predicted weight loss from the start of MWM until 12 months post-surgery, but not postoperative weight loss after adjustment. The proportion of weight loss from start of MWM to 12 months post-surgery attributed to GLP-1RA treatment was negatively associated with that attributed to surgery, after adjustment. In conclusion, weight change after GLP-1RA treatment predicted the weight loss achieved by a combination of MWM and bariatric surgery, but not weight loss induced by surgery only. Failure to lose weight after GLP-1RA treatment should not be considered a barrier to undergoing bariatric surgery. © 2017 John Wiley & Sons Ltd.

  19. Involvement of gut microbiota in association between GLP-1/GLP-1 receptor expression and gastrointestinal motility.

    PubMed

    Yang, Mo; Fukui, Hirokazu; Eda, Hirotsugu; Xu, Xin; Kitayama, Yoshitaka; Hara, Ken; Kodani, Mio; Tomita, Toshihiko; Oshima, Tadayuki; Watari, Jiro; Miwa, Hiroto

    2017-04-01

    The microbiota in the gut is known to play a pivotal role in host physiology by interacting with the immune and neuroendocrine systems in gastrointestinal (GI) tissues. Glucagon-like peptide 1 (GLP-1), a gut hormone, is involved in metabolism as well as GI motility. We examined how gut microbiota affects the link between GLP-1/GLP-1 receptor (GLP-1R) expression and motility of the GI tract. Germ-free (GF) mice (6 wk old) were orally administered a fecal bacterial suspension prepared from specific pathogen-free (SPF) mice, and then after fecal transplantation (FT) GI tissues were obtained from the GF mice at various time points. The expression of GLP-1 and its receptor was examined by immunohistochemistry, and gastrointestinal transit time (GITT) was measured by administration of carmine red solution. GLP-1 was expressed in endocrine cells in the colonic mucosa, and GLP-1R was expressed in myenteric neural cells throughout the GI wall. GLP-1R-positive cells throughout the GI wall were significantly fewer in GF mice with FT than in GF mice without gut microbiota reconstitution. GITT was significantly shorter in GF mice with FT than in control GF mice without FT and correlated with the number of GLP-1R-positive cells throughout the GI wall. GITT was significantly longer in GF control mice than in SPF mice. When those mice were treated with GLP-1 agonist extendin4, GITT was significantly longer in the GF mice. The gut microbiota may accelerate or at least modify GI motility while suppressing GLP-1R expression in myenteric neural cells throughout the GI tract. NEW & NOTEWORTHY The gut microbiota has been intensively studied, because it plays a pivotal role in various aspects of host physiology. On the other hand, glucagon-like peptide 1 (GLP-1) plays important roles in metabolism as well as gastrointestinal motility. In the present study, we have suggested that the gut microbiota accelerates gastrointestinal motility while suppressing the expression of GLP-1 receptor in

  20. Exenatide exerts a PKA-dependent positive inotropic effect in human atrial myocardium: GLP-1R mediated effects in human myocardium.

    PubMed

    Wallner, Markus; Kolesnik, Ewald; Ablasser, Klemens; Khafaga, Mounir; Wakula, Paulina; Ljubojevic, Senka; Thon-Gutschi, Eva Maria; Sourij, Harald; Kapl, Martin; Edmunds, Nicholas J; Kuzmiski, J Brent; Griffith, David A; Knez, Igor; Pieske, Burkert; von Lewinski, Dirk

    2015-12-01

    Glucagon-like peptide-1 receptor (GLP-1R) agonists are a rapidly growing class of drugs developed for treating type-2 diabetes mellitus. Patients with diabetes carry an up to 5-fold greater mortality risk compared to non-diabetic patients, mainly as a result of cardiovascular diseases. Although beneficial cardiovascular effects have been reported, exact mechanisms of GLP-1R-agonist action in the heart, especially in human myocardium, are poorly understood. The effects of GLP-1R-agonists (exenatide, GLP-1(7-36)NH2, PF-06446009, PF-06446667) on cardiac contractility were tested in non-failing atrial and ventricular trabeculae from 72 patients. The GLP-1(7-36)NH2 metabolite, GLP-1(9-36)NH2, was also examined. In electrically stimulated trabeculae, the effects of compounds on isometric force were measured in the absence and presence of pharmacological inhibitors of signal transduction pathways. The role of β-arrestin signaling was examined using a β-arrestin partial agonist, PF-06446667. Expression levels were tested by immunoblots. Translocation of GLP-1R downstream molecular targets, Epac2, GLUT-1 and GLUT-4, were assessed by fluorescence microscopy. All tested GLP-1R-agonists significantly increased developed force in human atrial trabeculae, whereas GLP-1(9-36)NH2 had no effect. Exendin(9-39)NH2, a GLP-1R-antagonist, and H-89 blunted the inotropic effect of exenatide. In addition, exenatide increased PKA-dependent phosphorylation of phospholamban (PLB), GLUT-1 and Epac2 translocation, but not GLUT-4 translocation. Exenatide failed to enhance contractility in ventricular myocardium. Quantitative real-time PCR (qRT-PCR) revealed a significant higher GLP-1R expression in the atrium compared to ventricle. Exenatide increased contractility in a dose-dependent manner via GLP-1R/cAMP/PKA pathway and induced GLUT-1 and Epac2 translocation in human atrial myocardium, but had no effect in ventricular myocardium. Therapeutic use of GLP-1R-agonists may therefore impart

  1. Long-term management of type 2 diabetes with glucagon-like peptide-1 receptor agonists.

    PubMed

    Courtney, Hamish; Nayar, Rahul; Rajeswaran, Chinnadorai; Jandhyala, Ravi

    2017-01-01

    Continuously reducing excess blood glucose is a primary goal for the management of type 2 diabetes (T2D). Most patients with T2D require glucose-lowering medications to achieve and maintain adequate glycemic control; however, treatment failure may occur, limiting treatment options. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are an emerging therapeutic class that can be prescribed for patients instead of basal insulin after the failure of oral therapies. Recent studies have focused on the durability and tolerability of long-term GLP-1RA therapy. This review summarizes the key efficacy and safety findings from prospective phase 3 clinical studies of at least 76 weeks' duration for the GLP-1RAs currently approved in the United States and the European Union (albiglutide, dulaglutide, exenatide twice daily [BID], exenatide once weekly [QW], liraglutide, and lixisenatide). Currently, most of the long-term data are from uncontrolled extension studies, and continuous patient benefit has been observed for up to 3 years with multiple GLP-1RAs. Four-year comparative data demonstrated a longer time to treatment failure for exenatide BID than for sulfonylurea, and 3-year comparative extension data demonstrated greater glycated hemoglobin (HbA1c) reductions and weight loss with exenatide QW than with insulin glargine. Currently, the longest extension study for a GLP-1RA is the DURATION-1 study of exenatide QW, with >7 years of clinical data available. Data from DURATION-1 demonstrated that continuous HbA1c reductions and weight loss were observed for the patients continuing on the treatment, with no unexpected adverse events. Taken together, these data support GLP-1RAs as a long-term noninsulin treatment option after the failure of oral therapies.

  2. Functional importance of GLP-1 receptor species and expression levels in cell lines.

    PubMed

    Knudsen, Lotte Bjerre; Hastrup, Sven; Underwood, Christina Rye; Wulff, Birgitte Schjellerup; Fleckner, Jan

    2012-04-10

    Of the mammalian species, only the GLP-1 receptors of rat and human origin have been described and characterized. Here, we report the cloning of the homologous GLP-1 receptors from mouse, rabbit, pig, cynomolgus monkey and chimp. The GLP-1 receptor is highly conserved across species, thus underlining the physiological importance of the peptide hormone and its receptor across a wide range of mammals. We expressed the receptors by stable transfection of BHK cells, both in cell lines with high expression levels of the cloned receptors, as well as in cell lines with lower expression levels, more comparable to endogenous expression of these receptors. High expression levels of cloned GLP-1 receptors markedly increased the potency of GLP-1 and other high affinity ligands, whereas the K(d) values were not affected. For a low affinity ligand like the ago-allosteric modulator Compound 2, expression levels of the human GLP-1 receptor were important for maximal efficacy as well as potency. The two natural metabolites of GLP-1, GLP-1(9-37) and GLP-1(9-36)amide were agonists when tested on a cell line with high expression of the recombinant human GLP-1 receptor, whereas they behaved as (low potent) antagonists on a cell line that expressed the receptor endogenously, as well as cells expressing a moderate level of the recombinant human GLP-1 receptor. The amide form was a more potent agonist than the free acid from. In conclusion, receptor expression level is an important parametre for selecting cell lines with cloned GLP-1 receptors for functional characterization of physiological and pharmaceutical ligands. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Glucagon-like peptide 1 receptor (GLP-1R) expression by nerve fibres in inflammatory bowel disease and functional effects in cultured neurons.

    PubMed

    Anand, Uma; Yiangou, Yiangos; Akbar, Ayesha; Quick, Tom; MacQuillan, Anthony; Fox, Mike; Sinisi, Marco; Korchev, Yuri E; Jones, Ben; Bloom, Steve R; Anand, Praveen

    2018-01-01

    Glucagon like-peptide 1 receptor (GLP-1R) agonists diminish appetite and may contribute to the weight loss in inflammatory bowel disease (IBD). The aim of this study was to determine, for the first time, the expression of GLP-1R by colon nerve fibres in patients with IBD, and functional effects of its agonists in cultured rat and human sensory neurons. GLP-1R and other nerve markers were studied by immunohistochemistry in colon biopsies from patients with IBD (n = 16) and controls (n = 8), human dorsal root ganglia (DRG) tissue, and in GLP-1R transfected HEK293 cells. The morphological effects of incretin hormones oxyntomodulin, exendin-4 and glucagon were studied on neurite extension in cultured DRG neurons, and their functional effects on capsaicin and ATP signalling, using calcium imaging. Significantly increased numbers of colonic mucosal nerve fibres were observed in IBD biopsies expressing GLP-1R (p = 0.0013), the pan-neuronal marker PGP9.5 (p = 0.0008), and sensory neuropeptide CGRP (p = 0.0014). An increase of GLP-1R positive nerve fibres in IBD colon was confirmed with a different antibody to GLP-1R (p = 0.016). GLP-1R immunostaining was intensely positive in small and medium-sized neurons in human DRG, and in human and rat DRG cultured neurons. Co-localization of GLP-1R expression with neuronal markers in colon and DRG confirmed the neural expression of GLP-1R, and antibody specificity was confirmed in HEK293 cells transfected with the GLP-1R. Treatment with oxyntomodulin, exendin-4 and GLP-1 increased neurite length in cultured neurons compared with controls, but did not stimulate calcium influx directly, or affect capsaicin responses. However, exendin-4 significantly enhanced ATP responses in human DRG neurons. Our results show that increased GLP-1R innervation in IBD bowel could mediate enhanced visceral afferent signalling, and provide a peripheral target for therapeutic intervention. The differential effect of GLP-1R agonists on capsaicin and ATP

  4. Glucagon-like peptide 1 receptor (GLP-1R) expression by nerve fibres in inflammatory bowel disease and functional effects in cultured neurons

    PubMed Central

    Yiangou, Yiangos; Akbar, Ayesha; Quick, Tom; MacQuillan, Anthony; Fox, Mike; Sinisi, Marco; Korchev, Yuri E.; Jones, Ben; Bloom, Steve R.; Anand, Praveen

    2018-01-01

    Introduction Glucagon like-peptide 1 receptor (GLP-1R) agonists diminish appetite and may contribute to the weight loss in inflammatory bowel disease (IBD). Objectives The aim of this study was to determine, for the first time, the expression of GLP-1R by colon nerve fibres in patients with IBD, and functional effects of its agonists in cultured rat and human sensory neurons. Methods GLP-1R and other nerve markers were studied by immunohistochemistry in colon biopsies from patients with IBD (n = 16) and controls (n = 8), human dorsal root ganglia (DRG) tissue, and in GLP-1R transfected HEK293 cells. The morphological effects of incretin hormones oxyntomodulin, exendin-4 and glucagon were studied on neurite extension in cultured DRG neurons, and their functional effects on capsaicin and ATP signalling, using calcium imaging. Results Significantly increased numbers of colonic mucosal nerve fibres were observed in IBD biopsies expressing GLP-1R (p = 0.0013), the pan-neuronal marker PGP9.5 (p = 0.0008), and sensory neuropeptide CGRP (p = 0.0014). An increase of GLP-1R positive nerve fibres in IBD colon was confirmed with a different antibody to GLP-1R (p = 0.016). GLP-1R immunostaining was intensely positive in small and medium-sized neurons in human DRG, and in human and rat DRG cultured neurons. Co-localization of GLP-1R expression with neuronal markers in colon and DRG confirmed the neural expression of GLP-1R, and antibody specificity was confirmed in HEK293 cells transfected with the GLP-1R. Treatment with oxyntomodulin, exendin-4 and GLP-1 increased neurite length in cultured neurons compared with controls, but did not stimulate calcium influx directly, or affect capsaicin responses. However, exendin-4 significantly enhanced ATP responses in human DRG neurons. Conclusion Our results show that increased GLP-1R innervation in IBD bowel could mediate enhanced visceral afferent signalling, and provide a peripheral target for therapeutic intervention. The differential

  5. Molecular evolution of GPCRs: GLP1/GLP1 receptors.

    PubMed

    Hwang, Jong-Ik; Yun, Seongsik; Moon, Mi Jin; Park, Cho Rong; Seong, Jae Young

    2014-06-01

    Glucagon-like peptide 1 (GLP1) is an intestinal incretin that regulates glucose homeostasis through stimulation of insulin secretion from pancreatic β-cells and inhibits appetite by acting on the brain. Thus, it is a promising therapeutic agent for the treatment of type 2 diabetes mellitus and obesity. Studies using synteny and reconstructed ancestral chromosomes suggest that families for GLP1 and its receptor (GLP1R) have emerged through two rounds (2R) of whole genome duplication and local gene duplications before and after 2R. Exon duplications have also contributed to the expansion of the peptide family members. Specific changes in the amino acid sequence following exon/gene/genome duplications have established distinct yet related peptide and receptor families. These specific changes also confer selective interactions between GLP1 and GLP1R. In this review, we present a possible macro (genome level)- and micro (gene/exon level)-evolution mechanisms of GLP1 and GLP1R, which allows them to acquire selective interactions between this ligand-receptor pair. This information may provide critical insight for the development of potent therapeutic agents targeting GLP1R. © 2014 Society for Endocrinology.

  6. The non-peptide GLP-1 receptor agonist WB4-24 blocks inflammatory nociception by stimulating β-endorphin release from spinal microglia

    PubMed Central

    Fan, Hui; Gong, Nian; Li, Teng-Fei; Ma, Ai-Niu; Wu, Xiao-Yan; Wang, Ming-Wei; Wang, Yong-Xiang

    2015-01-01

    BACKGROUND AND PURPOSE Two peptide agonists of the glucagon-like peptide-1 (GLP-1) receptor, exenatide and GLP-1 itself, exert anti-hypersensitive effects in neuropathic, cancer and diabetic pain. In this study, we have assessed the anti-allodynic and anti-hyperalgesic effects of the non-peptide agonist WB4-24 in inflammatory nociception and the possible involvement of microglial β-endorphin and pro-inflammatory cytokines. EXPERIMENTAL APPROACH We used rat models of inflammatory nociception induced by formalin, carrageenan or complete Freund's adjuvant (CFA), to test mechanical allodynia and thermal hyperalgesia. Expression of β-endorphin and pro-inflammatory cytokines was measured using real-time quantitative PCR and fluorescent immunoassays. KEY RESULTS WB4-24 displaced the specific binding of exendin (9–39) in microglia. Single intrathecal injection of WB4-24 (0.3, 1, 3, 10, 30 and 100 μg) exerted dose-dependent, specific, anti-hypersensitive effects in acute and chronic inflammatory nociception induced by formalin, carrageenan and CFA, with a maximal inhibition of 60–80%. Spinal WB4-24 was not effective in altering nociceptive pain. Subcutaneous injection of WB4-24 was also antinociceptive in CFA-treated rats. WB4-24 evoked β-endorphin release but did not inhibit expression of pro-inflammatory cytokines in either the spinal cord of CFA-treated rats or cultured microglia stimulated by LPS. WB4-24 anti-allodynia was prevented by a microglial inhibitor, β-endorphin antiserum and a μ-opioid receptor antagonist. CONCLUSIONS AND IMPLICATIONS Our results suggest that WB4-24 inhibits inflammatory nociception by releasing analgesic β-endorphin rather than inhibiting the expression of proalgesic pro-inflammatory cytokines in spinal microglia, and that the spinal GLP-1 receptor is a potential target molecule for the treatment of pain hypersensitivity including inflammatory nociception. PMID:25176008

  7. Treatment Intensification in Type 2 Diabetes: A Real-World Study of 2-OAD Regimens, GLP-1 RAs, or Basal Insulin.

    PubMed

    Blonde, Lawrence; Raccah, Denis; Lew, Elisheva; Meyers, Juliana; Nikonova, Elena; Ajmera, Mayank; Davis, Keith L; Bertolini, Monica; Guerci, Bruno

    2018-06-01

    Treatment guidelines recommend a stepwise approach to glycemia management in patients with type 2 diabetes (T2D), but this may result in uncontrolled glycated hemoglobin A1c (HbA1c) between steps. This retrospective analysis compared clinical and economic outcomes among patients with uncontrolled T2D initiating two oral antidiabetes drugs (OADs), glucagon-like peptide-1 receptor agonists (GLP-1 RAs), or basal insulin in a real-world setting. Adults with T2D on OAD monotherapy were identified in the MarketScan claims database (2007-2014). Those initiating two OADs (simultaneously or sequentially), GLP-1 RAs, or basal insulin were selected (date of initiation was termed the 'index date'); patients were required to have HbA1c > 7.0% in the 6 months pre-index date. HbA1c was compared from 6 months pre- to 1-year post-index. Annual all-cause healthcare utilization and costs were reported over the 1-year follow-up period. Data for 6054 patients were analyzed (2-OAD, n = 4442; GLP-1 RA, n = 361; basal insulin, n = 1251). Baseline HbA1c was high in all cohorts, but highest in the basal-insulin cohort. Treatment initiation resulted in reductions in HbA1c in all cohorts, which was generally maintained throughout the follow-up period. Average HbA1c reductions from the 6 months pre- to 1 year post-index date were -1.2% for GLP-1 RA, -1.6% for OADs, and -1.8% for basal insulin. HbA1c < 7.0% at 1 year occurred in 32.6%, 47.5%, and 41.1% of patients, respectively. Annual healthcare costs (mean [SD]) were lowest for OAD (US$10,074 [$22,276]) followed by GLP-1 RA (US$14,052 [$23,829]) and basal insulin (US$18,813 [$37,332]). Despite robust HbA1c lowering following treatment initiation, many patients did not achieve HbA1c < 7.0%. Basal insulin, generally prescribed for patients with high baseline HbA1c, was associated with a large reduction in HbA1c and with higher costs. Therapy intensification at an appropriate time could lead to clinical and economic

  8. Novel Small Molecule Glucagon-Like Peptide-1 Receptor Agonist Stimulates Insulin Secretion in Rodents and From Human Islets

    PubMed Central

    Sloop, Kyle W.; Willard, Francis S.; Brenner, Martin B.; Ficorilli, James; Valasek, Kathleen; Showalter, Aaron D.; Farb, Thomas B.; Cao, Julia X.C.; Cox, Amy L.; Michael, M. Dodson; Gutierrez Sanfeliciano, Sonia Maria; Tebbe, Mark J.; Coghlan, Michael J.

    2010-01-01

    OBJECTIVE The clinical effectiveness of parenterally-administered glucagon-like peptide-1 (GLP-1) mimetics to improve glucose control in patients suffering from type 2 diabetes strongly supports discovery pursuits aimed at identifying and developing orally active, small molecule GLP-1 receptor agonists. The purpose of these studies was to identify and characterize novel nonpeptide agonists of the GLP-1 receptor. RESEARCH DESIGN AND METHODS Screening using cells expressing the GLP-1 receptor and insulin secretion assays with rodent and human islets were used to identify novel molecules. The intravenous glucose tolerance test (IVGTT) and hyperglycemic clamp characterized the insulinotropic effects of compounds in vivo. RESULTS Novel low molecular weight pyrimidine-based compounds that activate the GLP-1 receptor and stimulate glucose-dependent insulin secretion are described. These molecules induce GLP-1 receptor-mediated cAMP signaling in HEK293 cells expressing the GLP-1 receptor and increase insulin secretion from rodent islets in a dose-dependent manner. The compounds activate GLP-1 receptor signaling, both alone or in an additive fashion when combined with the endogenous GLP-1 peptide; however, these agonists do not compete with radiolabeled GLP-1 in receptor-binding assays. In vivo studies using the IVGTT and the hyperglycemic clamp in Sprague Dawley rats demonstrate increased insulin secretion in compound-treated animals. Further, perifusion assays with human islets isolated from a donor with type 2 diabetes show near-normalization of insulin secretion upon compound treatment. CONCLUSIONS These studies characterize the insulinotropic effects of an early-stage, small molecule GLP-1 receptor agonist and provide compelling evidence to support pharmaceutical optimization. PMID:20823098

  9. The GLP-1 agonist exendin-4 attenuates self-administration of sweetened fat on fixed and progressive ratio schedules of reinforcement

    PubMed Central

    Bernosky-Smith, Kimberly A.; Stanger, David B.; Trujillo, Alexandria J.; Mitchell, Luke R.; Espana, Rodrigo A.; Bass, Caroline E.

    2016-01-01

    GLP-1 agonists such as exendin-4 (EX4) are used in the treatment of type 2 diabetes and have the additional benefit of promoting weight loss. GLP-1 agonists decrease feeding through peripheral affects, but recent evidence suggests they may also influence sweet or high fat preference, as well as the motivation to obtain these tastants. Yet it remains unclear how GLP-1 induced alterations in food preference influences the decrease in overall feeding. The current study sought to determine if EX4 affects the reinforcing strength and consumption of a highly palatable sweet/fat reinforcer. Rats were trained to self-administer sweetened vegetable shortening (SVS) under fixed (FR) and progressive ratio (PR) schedules of reinforcement. EX4 (0.3 - 2.4 μg/kg, IP) administered one hour prior to operant sessions significantly reduced responding for SVS under both FR and PR schedules (e.g. total reinforcers and breakpoints, respectively), although the lowest active dose (0.6 μg/kg) significantly suppressed FR responding only. EX4 also dose dependently decreased locomotor activity (0.6-2.4 μg/kg doses), but did not enhance acute kaolin intake, indicating that EX4-induced nausea did not influence the self-administration results. Analysis of ED50 values show that EX4 is more effective at inhibiting FR responding versus PR, indicating that EX4 may have more potent effects on consummatory versus appetitive feeding behaviors. Although EX4 caused generalized behavioral suppression, these results cannot fully explain the decreases in operant responding. For example, the 0.6 μg/kg dose inhibited only FR responding, even though the rats were physically capable of responding at a higher rate during PR sessions. In addition, the rate of intake was constant at the beginning of the sessions in both PR and FR schedules, regardless of the dose. Together these data suggest that EX4 inhibits consumption of a palatable high sweet/high fat reinforcer potentially through altering satiety. PMID

  10. The GIP receptor displays higher basal activity than the GLP-1 receptor but does not recruit GRK2 or arrestin3 effectively.

    PubMed

    Al-Sabah, Suleiman; Al-Fulaij, Munya; Shaaban, Ghina; Ahmed, Hanadi A; Mann, Rosalind J; Donnelly, Dan; Bünemann, Moritz; Krasel, Cornelius

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are important regulators of insulin secretion, and their functional loss is an early characteristic of type 2 diabetes mellitus (T2DM). Pharmacological levels of GLP-1, but not GIP, can overcome this loss. GLP-1 and GIP exert their insulinotropic effects through their respective receptors expressed on pancreatic β-cells. Both the GLP-1 receptor (GLP-1R) and the GIP receptor (GIPR) are members of the secretin family of G protein-coupled receptors (GPCRs) and couple positively to adenylate cyclase. We compared the signalling properties of these two receptors to gain further insight into why GLP-1, but not GIP, remains insulinotropic in T2DM patients. GLP-1R and GIPR were transiently expressed in HEK-293 cells, and basal and ligand-induced cAMP production were investigated using a cAMP-responsive luciferase reporter gene assay. Arrestin3 (Arr3) recruitment to the two receptors was investigated using enzyme fragment complementation, confocal microscopy and fluorescence resonance energy transfer (FRET). GIPR displayed significantly higher (P<0.05) ligand-independent activity than GLP-1R. Arr3 displayed a robust translocation to agonist-stimulated GLP-1R but not to GIPR. These observations were confirmed in FRET experiments, in which GLP-1 stimulated the recruitment of both GPCR kinase 2 (GRK2) and Arr3 to GLP-1R. These interactions were not reversed upon agonist washout. In contrast, GIP did not stimulate recruitment of either GRK2 or Arr3 to its receptor. Interestingly, arrestin remained at the plasma membrane even after prolonged (30 min) stimulation with GLP-1. Although the GLP-1R/arrestin interaction could not be reversed by agonist washout, GLP-1R and arrestin did not co-internalise, suggesting that GLP-1R is a class A receptor with regard to arrestin binding. GIPR displays higher basal activity than GLP-1R but does not effectively recruit GRK2 or Arr3.

  11. Loss of dorsomedial hypothalamic GLP-1 signaling reduces BAT thermogenesis and increases adiposity.

    PubMed

    Lee, Shin J; Sanchez-Watts, Graciela; Krieger, Jean-Philippe; Pignalosa, Angelica; Norell, Puck N; Cortella, Alyssa; Pettersen, Klaus G; Vrdoljak, Dubravka; Hayes, Matthew R; Kanoski, Scott; Langhans, Wolfgang; Watts, Alan G

    2018-05-01

    Glucagon-like peptide-1 (GLP-1) neurons in the hindbrain densely innervate the dorsomedial hypothalamus (DMH), a nucleus strongly implicated in body weight regulation and the sympathetic control of brown adipose tissue (BAT) thermogenesis. Therefore, DMH GLP-1 receptors (GLP-1R) are well placed to regulate energy balance by controlling sympathetic outflow and BAT function. We investigate this possibility in adult male rats by using direct administration of GLP-1 (0.5 ug) into the DMH, knocking down DMH GLP-1R mRNA with viral-mediated RNA interference, and by examining the neurochemical phenotype of GLP-1R expressing cells in the DMH using in situ hybridization. GLP-1 administered into the DMH increased BAT thermogenesis and hepatic triglyceride (TG) mobilization. On the other hand, Glp1r knockdown (KD) in the DMH increased body weight gain and adiposity, with a concomitant reduction in energy expenditure (EE), BAT temperature, and uncoupling protein 1 (UCP1) expression. Moreover, DMH Glp1r KD induced hepatic steatosis, increased plasma TG, and elevated liver specific de-novo lipogenesis, effects that collectively contributed to insulin resistance. Interestingly, DMH Glp1r KD increased neuropeptide Y (NPY) mRNA expression in the DMH. GLP-1R mRNA in the DMH, however, was found in GABAergic not NPY neurons, consistent with a GLP-1R-dependent inhibition of NPY neurons that is mediated by local GABAergic neurons. Finally, DMH Glp1r KD attenuated the anorexigenic effects of the GLP-1R agonist exendin-4, highlighting an important role of DMH GLP-1R signaling in GLP-1-based therapies. Collectively, our data show that DMH GLP-1R signaling plays a key role for BAT thermogenesis and adiposity. Copyright © 2018 The Authors. Published by Elsevier GmbH.. All rights reserved.

  12. A role of PLC/PKC-dependent pathway in GLP-1-stimulated insulin secretion.

    PubMed

    Shigeto, Makoto; Cha, Chae Young; Rorsman, Patrik; Kaku, Kohei

    2017-04-01

    Glucagon-like peptide-1 (GLP-1) is an endogenous glucose-lowering hormone and GLP-1 receptor agonists are currently being used as antidiabetic drugs clinically. The canonical signalling pathway (including cAMP, Epac2, protein kinase A (PKA) and K ATP channels) is almost universally accepted as the main mechanism of GLP-1-stimulated insulin secretion. This belief is based on in vitro studies that used nanomolar (1-100 nM) concentrations of GLP-1. Recently, it was found that the physiological concentrations (1-10 pM) of GLP-1 also stimulate insulin secretion from isolated islets, induce membrane depolarization and increase of intracellular [Ca 2+ ] in isolated β cells/pancreatic islets. These responses were unaffected by PKA inhibitors and occurred without detectable increases in intracellular cAMP and PKA activity. These PKA-independent actions of GLP-1 depend on protein kinase C (PKC), involve activation of the standard GLP-1 receptor (GLP1R) and culminate in activation of phospholipase C (PLC), leading to an elevation of diacylglycerol (DAG), increased L-type Ca 2+ and TRPM4/TRPM5 channel activities. Here, we review these recent data and contrast them against the effects of nanomolar concentrations of GLP-1. The differential intracellular signalling activated by low and high concentrations of GLP-1 could provide a clue to explain how GLP-1 exerts different function in the central nervous system and peripheral organs.

  13. Mechanisms of Action of GLP-1 in the Pancreas

    PubMed Central

    Doyle, Máire E.; Egan, Josephine M.

    2007-01-01

    Glucagon-like peptide-1 is a hormone that is encoded in the proglucagon gene. It is mainly produced in enteroendocrine L cells of the gut and is secreted into the blood stream when food containing fat, protein hydrolysate and/or glucose enters the duodenum. Its particular effects on insulin and glucagon secretion have generated a flurry of research activity over the past twenty years culminating in a naturally occurring GLP-1 receptor agonist, exendin-4, now being used to treat type 2 diabetes. GLP-1 engages a specific G-protein coupled receptor that is present in tissues other than the pancreas (brain, kidney, lung, heart, major blood vessels). The most widely studied cell activated by GLP-1 is the insulin-secreting beta cell where its defining action is augmentation of glucose-induced insulin secretion. Upon GLP-1 receptor activation, adenylyl cyclase is activated and cAMP generated, leading, in turn, to cAMP-dependent activation of second messenger pathways, such as the PKA and Epac pathways. As well as short-term effects of enhancing glucose-induced insulin secretion, continuous GLP-1 receptor activation also increases insulin synthesis, and beta cell proliferation and neogenesis. Although these latter effects cannot be currently monitored in humans, there are substantial improvements in glucose tolerance and increases in both first phase and plateau phase insulin secretory responses in type 2 diabetic patients treated with exendin-4. This review we will focus on the effects resulting from GLP-1 receptor activation in islets of Langerhans PMID:17306374

  14. Xenopus-derived glucagon-like peptide-1 and polyethylene-glycosylated glucagon-like peptide-1 receptor agonists: long-acting hypoglycaemic and insulinotropic activities with potential therapeutic utilities.

    PubMed

    Han, Jing; Fei, Yingying; Zhou, Feng; Chen, Xinyu; Zhang, Ying; Liu, Lin; Fu, Junjie

    2018-02-01

    Incretin-based therapies based on glucagon-like peptide-1 (GLP-1) receptor agonists are effective treatments of type 2 diabetes. Abundant research has focused on the development of long-acting GLP-1 receptor agonists. However, all GLP-1 receptor agonists in clinical use or development are based on human or Gila GLP-1. We have identified a potent GLP-1 receptor agonist, xGLP-1B, based on Xenopus GLP-1. To further modify the structure of xGLP-1B, alanine scanning was performed to study the structure -activity relationship of xGLP-1B. Two strategies were then employed to improve bioactivity. First, the C-terminal tail of lixisenatide was appended to cysteine-altered xGLP-1B analogues. Second, polyethylene glycol (PEG) chains with different molecular weights were conjugated with the peptides, giving a series of PEGylated conjugates. Comprehensive bioactivity studies of these conjugates were performed in vitro and in vivo. From the in vitro receptor activation potency and in vivo acute hypoglycaemic activities of conjugates 25 -36, 33 was identified as the best candidate for further biological assessments. Conjugate 33 exhibited prominent hypoglycaemic and insulinotropic activities, as well as improved pharmacokinetic profiles in vivo. The prolonged antidiabetic duration of 33 was further confirmed by pre-oral glucose tolerance tests (OGTT) and multiple OGTT. Furthermore, chronic treatment of db/db mice with 33 ameliorated non-fasting blood glucose and insulin levels, reduced HbA1c values and normalized their impaired glucose tolerance. Importantly, no in vivo toxicity was observed in mice treated with 33. Peptide 33 is a promising long-acting type 2 diabetes therapeutic deserving further investigation. © 2017 The British Pharmacological Society.

  15. Antiobesity efficacy of GLP-1 receptor agonist liraglutide is associated with peripheral tissue-specific modulation of lipid metabolic regulators.

    PubMed

    Decara, Juan; Arrabal, Sergio; Beiroa, Daniel; Rivera, Patricia; Vargas, Antonio; Serrano, Antonia; Pavón, Francisco Javier; Ballesteros, Joan; Dieguez, Carlos; Nogueiras, Rubén; Rodríguez de Fonseca, Fernando; Suárez, Juan

    2016-11-12

    To investigate the role of glucagon-like-peptide-1 receptor (GLP-1R) in peripheral lipid metabolism. Both lean and high-fat diet (HFD)-induced obesity (DIO) rats were used to compare the peripheral effects of the subcutaneous and repeated administration of the GLP-1R agonist liraglutide on the expression of key regulators involved in lipid metabolism, β-oxidation and thermogenesis in liver, abdominal muscle, and epididymal white adipose tissue (eWAT). We observed that liraglutide reduced caloric intake, body weight, and plasma levels of triglycerides and VLDL in a diet-independent manner. However, changes in liver fat content and the expression of lipid metabolism regulators were produced in a diet and tissue-dependent manner. In lean rats, liraglutide increased the gene/protein expression of elements involved in lipogenesis (ChREBP, Acaca/ACC, Fasn/FAS, Scd1/SCD1, PPARα/γ), β-oxidation (CPT1b), and thermogenesis (Cox4i1, Ucp1/UCP1) in eWAT and muscle, which suggest an increase in fatty-acid flux and utilization to activate energy expenditure. Regarding DIO rats, the specific reduction of liver lipid content by liraglutide was associated with a decreased expression of main elements involved in lipogenesis (phospho-ACC), peroxisomal β-oxidation (ACOX1), and lipid flux/storage (Pparγ/PPARγ) in liver, which suggest a recovery of lipid homeostasis. Interestingly, the muscle of DIO rats treated with liraglutide showed a decreased expression of PPARγ and the thermogenic factor UCP1. These results help us to better understand the peripheral mechanisms regulating lipid metabolism that underlay the effectiveness of GLP-1 analogues for the treatment of diabetes and obesity. © 2016 BioFactors, 42(6):600-611, 2016. © 2016 International Union of Biochemistry and Molecular Biology.

  16. No cognitive-enhancing effect of GLP-1 receptor agonism in antipsychotic-treated, obese patients with schizophrenia.

    PubMed

    Ishøy, P L; Fagerlund, B; Broberg, B V; Bak, N; Knop, F K; Glenthøj, B Y; Ebdrup, B H

    2017-07-01

    Schizophrenia is associated with profound cognitive and psychosocial impairments. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are used for diabetes and obesity treatment, and animal studies have indicated cognitive-enhancing effects. In this investigator-initiated, double-blind, randomized, placebo-controlled trial, we tested non-metabolic effects of exenatide once-weekly (Bydureon™) in obese, antipsychotic-treated patients with schizohrenia spectrum disorder. Before and after 3 months of exenatide (N = 20) or placebo (N = 20) treatment, patients were assessed with the following: Brief Assessment of Cognition in Schizophrenia (BACS), Rey-Osterreith complex figure test (REY), Short-Form Health Survey (SF-36), Personal and Social Performance Scale (PSP) and the Positive and Negative Syndrome Scale (PANSS). We used BACS composite score as the main outcome measure. Repeated measures analysis of variance on BACS composite score showed significant effect of 'Time' (P < 0.001), no effect of 'Group' (P = 0.64) and no 'Time*Group' interaction (P = 0.77). For REY, SF-36, PSP and PANSS, only significant 'Time' effects were found. The non-significant results of this first clinical trial exploring non-metabolic effects of a long-acting GLP-1RA in patients with schizophrenia could reflect a general problem of translating cognitive-enhancing effects of GLP-1RAs from animals to humans or be explained by factors specifically related to schizophrenia spectrum patients with obesity such as antipsychotic treatment. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Benefits and challenges of a QSP approach through case study: Evaluation of a hypothetical GLP-1/GIP dual agonist therapy.

    PubMed

    Rieger, Theodore R; Musante, Cynthia J

    2016-10-30

    Quantitative Systems Pharmacology (QSP) is an emerging science with increasing application to pharmaceutical research and development paradigms. Through case study we provide an overview of the benefits and challenges of applying QSP approaches to inform program decisions in the early stages of drug discovery and development. Specifically, we describe the use of a type 2 diabetes systems model to inform a No-Go decision prior to lead development for a potential GLP-1/GIP dual agonist program, enabling prioritization of exploratory programs with higher probability of clinical success. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  18. Design of glucagon-like Peptide-1 receptor agonist for diabetes mellitus from traditional chinese medicine.

    PubMed

    Tang, Hsin-Chieh; Chen, Calvin Yu-Chian

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) is a promising target for diabetes mellitus (DM) therapy and reduces the occurrence of diabetes due to obesity. However, GLP-1 will be hydrolyzed soon by the enzyme dipeptidyl peptidase-4 (DPP-4). We tried to design small molecular drugs for GLP-1 receptor agonist from the world's largest traditional Chinese medicine (TCM) Database@Taiwan. According to docking results of virtual screening, we selected 2 TCM compounds, wenyujinoside and 28-deglucosylchikusetsusaponin IV, for further molecular dynamics (MD) simulation. GLP-1 was assigned as the control compound. Based on the results of root mean square deviation (RMSD), solvent accessible surface (SAS), mean square deviation (MSD), Gyrate, total energy, root mean square fluctuation (RMSF), matrices of smallest distance of residues, database of secondary structure assignment (DSSP), cluster analysis, and distance of H-bond, we concluded that all the 3 compounds could bind and activate GLP-1 receptor by computational simulation. Wenyujinoside and 28-deglucosylchikusetsusaponin IV were the TCM compounds that could be GLP-1 receptor agonists.

  19. Design of Glucagon-Like Peptide-1 Receptor Agonist for Diabetes Mellitus from Traditional Chinese Medicine

    PubMed Central

    Tang, Hsin-Chieh; Chen, Calvin Yu-Chian

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) is a promising target for diabetes mellitus (DM) therapy and reduces the occurrence of diabetes due to obesity. However, GLP-1 will be hydrolyzed soon by the enzyme dipeptidyl peptidase-4 (DPP-4). We tried to design small molecular drugs for GLP-1 receptor agonist from the world's largest traditional Chinese medicine (TCM) Database@Taiwan. According to docking results of virtual screening, we selected 2 TCM compounds, wenyujinoside and 28-deglucosylchikusetsusaponin IV, for further molecular dynamics (MD) simulation. GLP-1 was assigned as the control compound. Based on the results of root mean square deviation (RMSD), solvent accessible surface (SAS), mean square deviation (MSD), Gyrate, total energy, root mean square fluctuation (RMSF), matrices of smallest distance of residues, database of secondary structure assignment (DSSP), cluster analysis, and distance of H-bond, we concluded that all the 3 compounds could bind and activate GLP-1 receptor by computational simulation. Wenyujinoside and 28-deglucosylchikusetsusaponin IV were the TCM compounds that could be GLP-1 receptor agonists. PMID:24891870

  20. [Impact of anti-diabetic therapy based on glucagon-like peptide-1 receptor agonists on the cardiovascular risk of patients with type 2 diabetes mellitus].

    PubMed

    Camafort-Babkowski, Miguel

    2013-08-17

    Anti-diabetic drugs have, in addition to their well-known glucose lowering-effect, different effects in the rest of cardiovascular factors that are associated with diabetes mellitus. Glucagon-like peptide-1 (GLP-1) receptor agonists have recently been incorporated to the therapeutic arsenal of type 2 diabetes mellitus. The objective of this review is to summarize the available evidence on the effect of the GLP-1 receptor agonists on different cardiovascular risk factors, mediated by the effect of GLP-1 receptor agonists on the control of hyperglycaemia and the GLP-1 receptor agonists effect on other cardiovascular risk factors (weight control, blood pressure control, lipid profile and all other cardiovascular risk biomarkers). In addition, we present the emerging evidence with regards to the impact that GLP-1 receptor agonists therapy could have in the reduction of cardiovascular events and the currently ongoing studies addressing this issue. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  1. Glucagon-like peptide-1 receptor agonists and heart failure in type 2 diabetes: systematic review and meta-analysis of randomized and observational studies.

    PubMed

    Li, Ling; Li, Sheyu; Liu, Jiali; Deng, Ke; Busse, Jason W; Vandvik, Per Olav; Wong, Evelyn; Sohani, Zahra N; Bala, Malgorzata M; Rios, Lorena P; Malaga, German; Ebrahim, Shanil; Shen, Jiantong; Zhang, Longhao; Zhao, Pujing; Chen, Qunfei; Wang, Yingqiang; Guyatt, Gordon H; Sun, Xin

    2016-05-11

    The effect of glucagon-like peptide-1(GLP-1) receptor agonists on heart failure remains uncertain. We therefore conducted a systematic review to assess the possible impact of GLP-1 agonists on heart failure or hospitalization for heart failure in patients with type 2 diabetes. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL) and ClinicalTrials.gov to identify randomized controlled trials (RCTs) and observational studies that addressed the effect of GLP-1 receptor agonists in adults with type 2 diabetes, and explicitly reported heart failure or hospitalization for heart failure. Two paired reviewers screened reports, collected data, and assessed the risk of bias. We pooled data from RCTs and observational studies separately, and used the GRADE approach to rate the quality of evidence. We identified 25 studies that were eligible for our review; 21 RCTs (n = 18,270) and 4 observational studies (n = 111,029). Low quality evidence from 20 RCTs suggested, if anything, a lower incidence of heart failure between GLP-1 agonists versus control (17/7,441 vs. 19/4,317; odds ratio (OR) 0.62, 95 % confidence interval (CI) 0.31 to 1.22; risk difference (RD) 19 fewer, 95 % CI 34 fewer to 11 more per 1000 over 5 years). Three cohort studies comparing GLP-1 agonists to alternative agents provided very low quality evidence that GLP-1 agonists do not increase the incidence of heart failure. One RCT provided moderate quality evidence that GLP-1 agonists were not associated with hospitalization for heart failure (lixisenatide vs placebo: 122/3,034 vs. 127/3,034; adjusted hazard ratio 0.96, 95 % CI 0.75 to 1.23; RD 4 fewer, 95 % CI 25 fewer to 23 more per 1000 over 5 years) and a case-control study provided very low quality evidence also suggesting no association (GLP-1 agonists vs. other anti-hyperglycemic drugs: 1118 cases and 17,626 controls, adjusted OR 0.67, 95 % CI 0.32 to 1.42). The current evidence suggests that GLP-1 agonists do not

  2. Comparative effectiveness of glycemic control in patients with type 2 diabetes treated with GLP-1 receptor agonists: a network meta-analysis of placebo-controlled and active-comparator trials

    PubMed Central

    Orme, Michelle E; Nguyen, Hiep; Lu, Jackie Y; Thomas, Susan A

    2017-01-01

    Background Clinical studies of patients with type 2 diabetes show that GLP-1 receptor agonists (GLP-1 RAs) improve glycemic control and promote weight loss. We conducted a Bayesian network meta-analysis (NMA) of placebo- and active-controlled randomized trials to assess the comparative effectiveness of liraglutide, albiglutide, dulaglutide, and exenatide twice daily and once weekly, with a focus on glycemic control. Materials and methods We searched Medline, Embase, and the Cochrane Library (up to December 2014) for core registration programs for US-approved GLP-1 RAs. Patients reaching an A1C target of <7% were analyzed with a binomial model and change in A1C from baseline with a normal model. A covariate analysis assessed the impact of baseline A1C and treatment background on outcomes. Results The base-case NMA used 23 trials reporting A1C outcomes at ~6 month follow-up. The results, unadjusted and adjusted for baseline A1C, indicated that all GLP-1 RAs resulted in statistically significantly lower A1C at follow-up compared with placebo. The odds of reaching the <7% target were also significantly better compared with placebo. With dulaglutide, exenatide once weekly, and liraglutide, the absolute reduction in A1C at 6 months was 0.9%–1.4%, and was significantly better than exenatide twice daily. Albiglutide was not significantly different from exenatide twice daily. We estimate that ~50% of patients will meet the <7% A1C target within 6 months of commencing GLP-1 RAs. Conclusion This was a comprehensive assessment of the comparative effectiveness of GLP-1 RAs and A1C outcome. GLP-1 RAs are a viable addition to oral antidiabetes therapy, and dulaglutide, exenatide once weekly, and liraglutide are the most effective. PMID:28435304

  3. The glucagon-like peptide-1 receptor in the ventromedial hypothalamus reduces short-term food intake in male mice by regulating nutrient sensor activity.

    PubMed

    Burmeister, Melissa A; Brown, Jacob D; Ayala, Jennifer E; Stoffers, Doris A; Sandoval, Darleen A; Seeley, Randy J; Ayala, Julio E

    2017-12-01

    Pharmacological activation of the glucagon-like peptide-1 receptor (GLP-1R) in the ventromedial hypothalamus (VMH) reduces food intake. Here, we assessed whether suppression of food intake by GLP-1R agonists (GLP-1RA) in this region is dependent on AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR). We found that pharmacological inhibition of glycolysis, and thus activation of AMPK, in the VMH attenuates the anorectic effect of the GLP-1R agonist exendin-4 (Ex4), indicating that glucose metabolism and inhibition of AMPK are both required for this effect. Furthermore, we found that Ex4-mediated anorexia in the VMH involved mTOR but not acetyl-CoA carboxylase, two downstream targets of AMPK. We support this by showing that Ex4 activates mTOR signaling in the VMH and Chinese hamster ovary (CHO)-K1 cells. In contrast to the clear acute pharmacological impact of the these receptors on food intake, knockdown of the VMH Glp1r conferred no changes in energy balance in either chow- or high-fat-diet-fed mice, and the acute anorectic and glucose tolerance effects of peripherally dosed GLP-1RA were preserved. These results show that the VMH GLP-1R regulates food intake by engaging key nutrient sensors but is dispensable for the effects of GLP-1RA on nutrient homeostasis. Copyright © 2017 the American Physiological Society.

  4. Can GLP-1 preparations be used in children and adolescents with diabetes mellitus?

    PubMed

    Shehadeh, Naim; Daich, Eena; Zuckerman-Levin, Nehama

    2014-03-01

    The number of young diabetics is increasing and therapeutic options for these patients are limited. Glucagon-like peptide-1 (GLP-1) is secreted from the gut after meals and enhances glucose-induced insulin secretion, inhibits glucagon secretion, suppresses appetite, and delays the gastric-emptying rate. GLP-1 analogs are already widely used in the adult population to improve glycemic control and induce weight loss in overweight subjects with type 2 diabetes. The glucose-lowering effects resulting from the inhibition of glucagon secretion and the gastric-emptying rate could be of clinical importance in type 1 diabetes. In this article we review clinical data regarding the use of GLP-1 receptor agonists in youth and address the potential benefits and safety aspects of these compounds. Large scale clinical trials are still needed in the pediatric population.

  5. Major adverse cardiovascular event reduction with GLP-1 and SGLT2 agents: evidence and clinical potential

    PubMed Central

    Røder, Michael E.

    2017-01-01

    Treatment of patients with type 2 diabetes is directed against treating symptoms of hyperglycemia, minimizing the risk of hypoglycemia, and the risk of microvascular and macrovascular complications. The majority of patients with type 2 diabetes die from cardiovascular or cerebrovascular disease. Future therapies should therefore focus on reducing cardiovascular morbidity in this high-risk population. Glucagon-like peptide-1 receptor agonists (GLP-1RA) and sodium-glucose co-transporter 2 inhibitors (SGLT2-i) are two drug classes with proven antihyperglycemic effect in type 2 diabetes. However, these drugs seem to have other effects such as weight reduction, low risk of hypoglycemia, and blood pressure reduction. Emerging evidence suggests pleiotropic effects, which potentially could be important in reducing cardiovascular risk. Prompted by regulatory authorities demanding cardiovascular outcome trials (CVOTs) assessing the cardiovascular safety of new antihyperglycemic drug candidates, many CVOTs are ongoing and a few of these are finalized. Somewhat surprising recent CVOTs in both drug classes have shown promising data on cardiovascular morbidity and mortality in patients with a very high risk of cardiovascular events. It is uncertain whether this is a class effect of the two drug classes, and it is yet unproven whether long-term cardiovascular benefits of these drugs can be extrapolated to populations at lower risk of cardiovascular disease. The aim of the present review is to give an overview of our current knowledge of the GLP-1RA and SGLT2-i classes, with specific focus on mechanisms of action, effects on cardiovascular risk factors and cardiovascular morbidity and mortality from the CVOTs presently available. The clinical potential of these data is discussed. PMID:29344329

  6. Recombinant human GLP-1(rhGLP-1) alleviating renal tubulointestitial injury in diabetic STZ-induced rats.

    PubMed

    Yin, Weiqin; Xu, Shiqing; Wang, Zai; Liu, Honglin; Peng, Liang; Fang, Qing; Deng, Tingting; Zhang, Wenjian; Lou, Jinning

    2018-01-01

    GLP-1-based treatment improves glycemia through stimulation of insulin secretion and inhibition of glucagon secretion. Recently, more and more findings showed that GLP-1 could also protect kidney from diabetic nephropathy. Most of these studies focused on glomeruli, but the effect of GLP-1 on tubulointerstitial and tubule is not clear yet. In this study, we examined the renoprotective effect of recombinant human GLP-1 (rhGLP-1), and investigated the influence of GLP-1 on inflammation and tubulointerstitial injury using diabetic nephropathy rats model of STZ-induced. The results showed that rhGLP-1 reduced urinary albumin without influencing the body weight and food intake. rhGLP-1 could increased the serum C-peptide slightly but not lower fasting blood glucose significantly. In diabetic nephropathy rats, beside glomerular sclerosis, tubulointerstitial fibrosis was very serious. These lesions could be alleviated by rhGLP-1. rhGLP-1 decreased the expression of profibrotic factors collagen I, α-SMA, fibronectin, and inflammation factors MCP-1 and TNFα in tubular tissue and human proximal tubular cells (HK-2 cells). Furthermore, rhGLP-1 significantly inhibited the phosphorylation of NF-κB, MAPK in both diabetic tubular tissue and HK-2 cells. The inhibition of the expression of TNFα, MCP-1, collagen I and α-SMA in HK-2 cells by GLP-1 could be mimicked by blocking NF-κB or MAPK. These results indicate that rhGLP-1 exhibit renoprotective effect by alleviation of tubulointerstitial injury via inhibiting phosphorylation of MAPK and NF-κB. Therefore, rhGLP-1 may be a potential drug for treatment of diabetic nephropathy. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. New screening strategy and analysis for identification of allosteric modulators for glucagon-like peptide-1 receptor using GLP-1 (9-36) amide.

    PubMed

    Nakane, Atsushi; Gotoh, Yusuke; Ichihara, Junji; Nagata, Hidetaka

    2015-12-15

    The glucagon-like peptide-1 receptor (GLP-1R) is an important physiologic regulator of insulin secretion and a major therapeutic target for diabetes mellitus. GLP-1 (7-36) amide (active form of GLP-1) is truncated to GLP-1 (9-36) amide, which has been described as a weak agonist of GLP-1R and the major form of GLP-1 in the circulation. New classes of positive allosteric modulators (PAMs) for GLP-1R may offer improved therapeutic profiles. To identify these new classes, we developed novel and robust primary and secondary high-throughput screening (HTS) systems in which PAMs were identified to enhance the GLP-1R signaling induced by GLP-1 (9-36) amide. Screening enabled identification of two compounds, HIT-465 and HIT-736, which possessed new patterns of modulation of GLP-1R. We investigated the ability of these compounds to modify GLP-1R signaling enhanced GLP-1 (9-36) amide- and/or GLP-1 (7-36) amide-mediated cyclic adenosine monophosphate (cAMP) accumulation. These compounds also had unique profiles with regard to allosteric modulation of multiple downstream signaling (PathHunter β-arrestin signaling, PathHunter internalization signaling, microscopy-based internalization assay). We found allosteric modulation patterns to be obviously different among HIT-465, HIT-736, and Novo Nordisk compound 2. This work may enable the design of new classes of drug candidates by targeting modulation of GLP-1 (7-36) amide and GLP-1 (9-36) amide. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Comparison Review of Short-Acting and Long-Acting Glucagon-like Peptide-1 Receptor Agonists.

    PubMed

    Uccellatore, Annachiara; Genovese, Stefano; Dicembrini, Ilaria; Mannucci, Edoardo; Ceriello, Antonio

    2015-09-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) are useful tools for treating type 2 diabetes mellitus. In their recent position statement, the American Diabetes Association and European Association for the Study of Diabetes recommend GLP1-RAs as add-on to metformin when therapeutic goals are not achieved with monotherapy, particularly for patients who wish to avoid weight gain or hypoglycemia. GLP1-RAs differ substantially in their duration of action, frequency of administration and clinical profile. Members of this class approved for clinical use include exenatide twice-daily, exenatide once-weekly, liraglutide and lixisenatide once-daily. Recently, two new once-weekly GLP1-RAs have been approved: dulaglutide and albiglutide. This article summarizes properties of short- and long-acting GLP-1 analogs, and provides useful information to help choose the most appropriate compound for individual patients.

  9. GLP-1 nanomedicine alleviates gut inflammation

    PubMed Central

    Anbazhagan, Arivarasu N.; Thaqi, Mentor; Priyamvada, Shubha; Jayawardena, Dulari; Kumar, Anoop; Gujral, Tarunmeet; Chatterjee, Ishita; Mugarza, Edurne; Saksena, Seema; Onyuksel, Hayat; Dudeja, Pradeep K.

    2017-01-01

    The gut hormone, glucagon like peptide-1 (GLP-1) exerts anti-inflammatory effects. However, its clinical use is limited by its short half-life. Previously, we have shown that GLP-1 as a nanomedicine (GLP-1 in sterically stabilized phospholipid micelles, GLP-1-SSM) has increased in vivo stability. The current study was aimed at testing the efficacy of this GLP-1 nanomedicine in alleviating colonic inflammation and associated diarrhea in dextran sodium sulfate (DSS) induced mouse colitis model. Our results show that GLP-1-SSM treatment markedly alleviated the colitis phenotype by reducing the expression of pro-inflammatory cytokine IL-1β, increasing goblet cells and preserving intestinal epithelial architecture in colitis model. Further, GLP-1-SSM alleviated diarrhea (as assessed by luminal fluid) by increasing protein expression of intestinal chloride transporter DRA (down regulated in adenoma). Our results indicate thatGLP-1 nanomedicine may act as a novel therapeutic tool in alleviating gut inflammation and associated diarrhea in inflammatory bowel disease (IBD). PMID:27553076

  10. Suppression of Food Intake by Glucagon-Like Peptide-1 Receptor Agonists: Relative Potencies and Role of Dipeptidyl Peptidase-4

    PubMed Central

    Jessen, Lene; Aulinger, Benedikt A.; Hassel, Jonathan L.; Roy, Kyle J.; Smith, Eric P.; Greer, Todd M.; Woods, Stephen C.; Seeley, Randy J.

    2012-01-01

    Administration of the glucagon-like peptide-1 (GLP-1) receptor agonists GLP-1 and exendin-4 (Ex-4) directly into the central nervous system decreases food intake. But although Ex-4 potently suppresses food intake after peripheral administration, the effects of parenteral GLP-1 are variable and not as strong. A plausible explanation for these effects is the rapid inactivation of circulating GLP-1 by dipeptidyl peptidase-4 (DPP-4), an enzyme that does not alter Ex-4 activity. To test this hypothesis, we assessed the relative potency of Ex-4 and GLP-1 under conditions in which DPP-4 activity was reduced. Outbred rats, wild-type mice, and mice with a targeted deletion of DPP-4 (Dpp4−/−) were treated with GLP-1 alone or in combination with the DPP-4 inhibitor vildagliptin, Ex-4, or saline, and food intake was measured. GLP-1 alone, even at high doses, did not affect feeding in wild-type mice or rats but did reduce food intake when combined with vildagliptin or given to Dpp4−/− mice. Despite plasma clearance similar to DPP-4-protected GLP-1, equimolar Ex-4 caused greater anorexia than vildagliptin plus GLP-1. To determine whether supraphysiological levels of endogenous GLP-1 would suppress food intake if protected from DPP-4, rats with Roux-en-Y gastric bypass and significantly elevated postprandial plasma GLP-1 received vildagliptin or saline. Despite 5-fold greater postprandial GLP-1 in these animals, vildagliptin did not affect food intake in Roux-en-Y gastric bypass rats. Thus, in both mice and rats, peripheral GLP-1 reduces food intake significantly less than Ex-4, even when protected from DPP-4. These findings suggest distinct potencies of GLP-1 receptor agonists on food intake that cannot be explained by plasma pharmacokinetics. PMID:23033273

  11. Endogenous GLP-1 as a key self-defense molecule against lipotoxicity in pancreatic islets.

    PubMed

    Huang, Chenghu; Yuan, Li; Cao, Shuyi

    2015-07-01

    The number of pro-α cells is known to increase in response to β cell injury and these cells then generate glucagon-like peptide-1 (GLP-1), thus attenuating the development of diabetes. The aim of the present study was to further examine the role and the mechanisms responsible for intra-islet GLP-1 production as a self-protective response against lipotoxicity. The levels of the key enzyme, prohormone convertase 1/3 (PC1/3), as well as the synthesis and release of GLP-1 in models of lipotoxicity were measured. Furthermore, islet viability, apoptosis, oxidative stress and inflammation, as well as islet structure were assessed after altering GLP-1 receptor signaling. Both prolonged exposure to palmitate and a high-fat diet facilitated PC1/3 expression, as well as the synthesis and release of GLP-1 induced by β cell injury and the generation of pro-α cells. Prolonged exposure to palmitate increased reactive oxygen species (ROS) production, and the antioxidant, N-acetylcysteine (NAC), partially prevented the detrimental effects induced by palmitate on β cells, resulting in decreased GLP-1 levels. Furthermore, the inhibition of GLP-1 receptor (GLP-1R) signaling by treatment with exendin‑(9-39) further decreased cell viability, increased cell apoptosis and caused a stronger inhibition of the β cell-specific transcription factor, pancreatic duodenal homeobox 1 (PDX1). Moreover, treatment with the GLP-1R agonist, liraglutide, normalized islet structure and function, resulting in a decrease in cell death and in the amelioration of β cell marker expression. Importantly, liraglutide maintained the oxidative balance and decreased inflammatory factor and p65 expression. Overall, our data demonstrate that an increase in the number of pro-α cells and the activation of the intra-islet GLP-1 system comprise a self-defense mechanism for enhancing β cell survival to combat lipid overload, which is in part mediated by oxidative stress and inflammation.

  12. Efficacy and safety of glucagon-like peptide-1 agonists on macrovascular and microvascular events in type 2 diabetes mellitus: A meta-analysis.

    PubMed

    Gargiulo, P; Savarese, G; D'Amore, C; De Martino, F; Lund, L H; Marsico, F; Dellegrottaglie, S; Marciano, C; Trimarco, B; Perrone-Filardi, P

    2017-12-01

    Glucagon-like peptide-1 (GLP-1) agonists improve glycaemic control in type 2 diabetes mellitus (DM). Outcome trials investigating macro and microvascular effects of GLP-1 agonists reported conflicting results. The aim of this study was to assess, in a meta-analysis, the effects of GLP-1 agonists on mortality, major nonfatal cardiovascular (CV) events, renal and retinal events. MEDLINE, Cochrane, ISI Web of Science, SCOPUS and ClinicalTrial.gov databases were searched for articles published until June 2017. Randomized trials enrolling more than 200 patients, comparing GLP-1 versus placebo or active treatments in patients with DM, and assessing outcomes among all-cause death, CV death, MI, stroke, HF, diabetic retinopathy and nephropathy were included. 77 randomized trials enrolling 60,434 patients were included. Compared to control, treatment with GLP-1 significantly reduced the risk of all-cause death (RR: 0.888; CI: 0.804-0.979; p = 0.018) and the risk of CV death (RR: 0.858; CI: 0.757-0.973; p = 0.017). GLP-1 agonists did not affect the risk of MI (RR: 0.917; CI: 0.830-1.014; p = 0.092) as well as the risk of stroke (RR: 0.882; CI: 0.759-1.023; p = 0.097), HF (RR: 0.967; CI: 0.803-1.165; p = 0.725), retinopathy (RR: 1.000; CI: 0.807-1.238; p = 0.997) and nephropathy (RR: 0.866; CI: 0.625-1.199; p = 0.385). Treatment with GLP-1 agonists in DM patients is associated with a significant reduction of all cause and CV mortality. Copyright © 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.

  13. Brain GLP-1 and insulin sensitivity

    USDA-ARS?s Scientific Manuscript database

    Type 2 diabetes is often treated with a class of drugs referred to as glucagon-like peptide-1 (GLP-1) analogs. GLP-1 is a peptide secreted by the gut that acts through only one known receptor, the GLP-1 receptor. The primary function of GLP-1 is thought to be lowering of postprandial glucose levels....

  14. Risk of bone fractures associated with glucagon-like peptide-1 receptor agonists' treatment: a meta-analysis of randomized controlled trials.

    PubMed

    Su, Bin; Sheng, Hui; Zhang, Manna; Bu, Le; Yang, Peng; Li, Liang; Li, Fei; Sheng, Chunjun; Han, Yuqi; Qu, Shen; Wang, Jiying

    2015-02-01

    Traditional anti-diabetic drugs may have negative or positive effects on risk of bone fractures. Yet the relationship between the new class glucagon-like peptide-1 receptor agonists (GLP-1 RA) and risk of bone fractures has not been established. We performed a meta-analysis including randomized controlled trials (RCT) to study the risk of bone fractures associated with liraglutide or exenatide, compared to placebo or other active drugs. We searched MEDLINE, EMBASE, and clinical trial registration websites for published or unpublished RCTs comparing the effects of liraglutide or exenatide with comparators. Only studies with disclosed bone fracture data were included. Separate pooled analysis was performed for liraglutide or exenatide, respectively, by calculating Mantel-Haenszel odds ratio (MH-OR). 16 RCTs were identified including a total of 11,206 patients. Liraglutide treatment was associated with a significant reduced risk of incident bone fractures (MH-OR=0.38, 95% CI 0.17-0.87); however, exenatide treatment was associated with an elevated risk of incident bone fractures (MH-OR=2.09, 95% CI 1.03-4.21). Publication bias and heterogeneity between studies were not observed. Our study demonstrated a divergent risk of bone fractures associated with different GLP-1 RA treatments. The current findings need to be confirmed by future well-designed prospective or RCT studies.

  15. The role of the GLP-1/GLP-1R signaling pathway in regulating seizure susceptibility in rats.

    PubMed

    Zhang, Yusong; Fang, Jian; Feng, Wen; Sun, Qi; Xu, Jian; Xia, Qingxin

    2018-06-27

    This study aimed to investigate the role of glucagon-like peptide-1 (GLP-1)/GLP-1 receptor(R) signaling in the regulation of seizure susceptibility and to explore the potential mechanism in rats. Hyperthermia-induced seizures in SD rats were generated using hot bath methods, and seizure severity was measured according to Racine scores and electroencephalogram (EEG). Protein levels of GLP-1 and GLP-1R in the brain tissues of rats were evaluated through ELISA, western blot analysis, and immunohistochemistry to explore the possible roles of each in FS. Neuronal excitability, spontaneous inhibitory postsynaptic currents (sIPSCs) and transient receptor potential cation channel subfamily V member 1(TRPV1) currents were tested using the patch-clamp method in cultured hippocampal neurons. Significant decreases in the levels of GLP-1 and GLP-1R were observed in the hippocampi of rats compared to those in the control group. Furthermore, treatment with the GLP-1R pharmacological inhibitor exendin9-39 increased hyperthermia- induced seizure severity in rats and promoted neuronal firing activity in cultured neurons. Importantly, exendin9-39 and GLP-1R knockdown decreased the amplitude and frequency of sIPSCs in cultured neurons. In addition, GLP-1R knockdown elevated downstream TRPV1 expression and promoted capsaicin-induced TRPV1 function, which may regulate inhibitory neurotransmission to affect seizure susceptibility. The present study suggests that inhibition of GLP-1R signaling promotes seizure activity, which plays a key role in the pathogenesis of FS. Copyright © 2018. Published by Elsevier Inc.

  16. Partial blockade of Kv2.1 channel potentiates GLP-1's insulinotropic effects in islets and reduces its dose required for improving glucose tolerance in type 2 diabetic male mice.

    PubMed

    Sukma Rita, Rauza; Dezaki, Katsuya; Kurashina, Tomoyuki; Kakei, Masafumi; Yada, Toshihiko

    2015-01-01

    Glucagon-like peptide-1 (GLP-1)-based medicines have recently been widely used to treat type 2 diabetic patients, whereas adverse effects of nausea and vomiting have been documented. Inhibition of voltage-gated K(+) channel subtype Kv2.1 in pancreatic β-cells has been suggested to contribute to mild depolarization and promotion of insulin release. This study aimed to determine whether the blockade of Kv2.1 channels potentiates the insulinotropic effect of GLP-1 agonists. Kv2.1 channel blocker guangxitoxin-1E (GxTx) and GLP-1 agonist exendin-4 at subthreshold concentrations, when combined, markedly increased the insulin release and cytosolic Ca(2+) concentration ([Ca(2+)]i) in a glucose-dependent manner in mouse islets and β-cells. Exendin-4 at subthreshold concentration alone increased islet insulin release and β-cell [Ca(2+)]i in Kv2.1(+/-) mice. The [Ca(2+)]i response to subthreshold exendin-4 and GxTx in combination was attenuated by pretreatment with protein kinase A inhibitor H-89, indicating the protein kinase A dependency of the cooperative effect. Furthermore, subthreshold doses of GxTx and GLP-1 agonist liraglutide in combination markedly increased plasma insulin and improved glucose tolerance in diabetic db/db mice and NSY mice. These results demonstrate that a modest suppression of Kv2.1 channels dramatically raises insulinotropic potency of GLP-1-based drugs, which opens a new avenue to reduce their doses and associated adverse effects while achieving the same glycemic control in type 2 diabetes.

  17. Liraglutide, a GLP-1 receptor agonist, inhibits vascular smooth muscle cell proliferation by enhancing AMP-activated protein kinase and cell cycle regulation, and delays atherosclerosis in ApoE deficient mice.

    PubMed

    Jojima, Teruo; Uchida, Kohsuke; Akimoto, Kazumi; Tomotsune, Takanori; Yanagi, Kazunori; Iijima, Toshie; Suzuki, Kunihiro; Kasai, Kikuo; Aso, Yoshimasa

    2017-06-01

    Several studies have demonstrated that both native glucagon-like peptide-1 (GLP-1) and GLP-1 receptor agonists suppress the progression of atherosclerosis in animal models. We investigated whether liraglutide, a GLP-1 analogue, could prevent the development of atherosclerosis in apolipoprotein E knockout mice (ApoE -/- ) on a high-fat diet. We also examined the influence of liraglutide on angiotensin II-induced proliferation of rat vascular smooth muscle cells (VSMCs) via enhancement of AMP-activated protein kinase (AMPK) signaling and regulation of cell cycle progression. Treatment of ApoE -/- mice with liraglutide (400 μg/day for 4 weeks) suppressed atherosclerotic lesions and increased AMPK phosphorylation in the aortic wall. Liraglutide also improved the endothelial function of thoracic aortas harvested from ApoE -/- mice in an ex vivo study. Furthermore, liraglutide increased AMPK phosphorylation in rat VSMCs, while liraglutide-induced activation of AMPK was abolished by exendin 9-39, a GLP-1 antagonist. Moreover, angiotensin (Ang) II-induced proliferation of VSMCs was suppressed by liraglutide in a dose-dependent manner, and flow cytometry of Ang II-stimulated VSMCs showed that liraglutide reduced the percentage of cells in G2/M phase (by arrest in G0/G1 phase). These findings suggest that liraglutide may inhibit Ang II-induced VSMC proliferation by activating AMPK signaling and inducing cell cycle arrest, thus delaying the progression of atherosclerosis independently of its glucose-lowering effect. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Treatment with GLP1 receptor agonists reduce serum CRP concentrations in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials.

    PubMed

    Mazidi, Mohsen; Karimi, Ehsan; Rezaie, Peyman; Ferns, Gordon A

    2017-07-01

    To undertake a systematic review and meta-analysis of randomized controlled trials of the effect of glucagon-like peptide-1 receptor agonist (GLP-1 RAs) therapy on serum C-reactive protein (CRP) concentrations. PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched for the period up until March 16, 2016. Prospective studies evaluating the impact of GLP-1 RAs on serum CRP were identified. A random effects model (using the DerSimonian-Laird method) and generic inverse variance methods were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. Heterogeneity was quantitatively assessed using the I 2 index. Random effects meta-regression was performed using unrestricted maximum likelihood method to evaluate the impact of potential moderator. International Prospective Register for Systematic Reviews (PROSPERO) number CRD42016036868. Meta-analysis of the data from 7 treatment arms revealed a significant reduction in serum CRP concentrations following treatment with GLP-1 RAs (WMD -2.14 (mg/dL), 95% CI -3.51, -0.78, P=0.002; I 2 96.1%). Removal of one study in the meta-analysis did not change the result in the sensitivity analysis (WMD -2.14 (mg/dL), 95% CI -3.51, -0.78, P=0.002; I 2 96.1%), indicating that our results could not be solely attributed to the effect of a single study. Random effects meta-regression was performed to evaluate the impact of potential moderator on the estimated effect size. Changes in serum CRP concentration were associated with the duration of treatment (slope -0.097, 95% CI -0.158, -0.042, P<0.001). This meta-analysis suggests that GLP-1 RAs therapy causes a significant reduction in CRP. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Genomic approach to therapeutic target validation identifies a glucose-lowering GLP1R variant protective for coronary heart disease

    PubMed Central

    Scott, Robert A.; Freitag, Daniel F.; Li, Li; Chu, Audrey Y.; Surendran, Praveen; Young, Robin; Grarup, Niels; Stancáková, Alena; Chen, Yuning; V.Varga, Tibor; Yaghootkar, Hanieh; Luan, Jian'an; Zhao, Jing Hua; Willems, Sara M.; Wessel, Jennifer; Wang, Shuai; Maruthur, Nisa; Michailidou, Kyriaki; Pirie, Ailith; van der Lee, Sven J.; Gillson, Christopher; Olama, Ali Amin Al; Amouyel, Philippe; Arriola, Larraitz; Arveiler, Dominique; Aviles-Olmos, Iciar; Balkau, Beverley; Barricarte, Aurelio; Barroso, Inês; Garcia, Sara Benlloch; Bis, Joshua C.; Blankenberg, Stefan; Boehnke, Michael; Boeing, Heiner; Boerwinkle, Eric; Borecki, Ingrid B.; Bork-Jensen, Jette; Bowden, Sarah; Caldas, Carlos; Caslake, Muriel; Cupples, L. Adrienne; Cruchaga, Carlos; Czajkowski, Jacek; den Hoed, Marcel; Dunn, Janet A.; Earl, Helena M.; Ehret, Georg B.; Ferrannini, Ele; Ferrieres, Jean; Foltynie, Thomas; Ford, Ian; Forouhi, Nita G.; Gianfagna, Francesco; Gonzalez, Carlos; Grioni, Sara; Hiller, Louise; Jansson, Jan-Håkan; Jørgensen, Marit E.; Jukema, J. Wouter; Kaaks, Rudolf; Kee, Frank; Kerrison, Nicola D.; Key, Timothy J.; Kontto, Jukka; Kote-Jarai, Zsofia; Kraja, Aldi T.; Kuulasmaa, Kari; Kuusisto, Johanna; Linneberg, Allan; Liu, Chunyu; Marenne, Gaëlle; Mohlke, Karen L.; Morris, Andrew P.; Muir, Kenneth; Müller-Nurasyid, Martina; Munroe, Patricia B.; Navarro, Carmen; Nielsen, Sune F.; Nilsson, Peter M.; Nordestgaard, Børge G.; Packard, Chris J.; Palli, Domenico; Panico, Salvatore; Peloso, Gina M.; Perola, Markus; Peters, Annette; Poole, Christopher J.; Quirós, J. Ramón; Rolandsson, Olov; Sacerdote, Carlotta; Salomaa, Veikko; Sánchez, María-José; Sattar, Naveed; Sharp, Stephen J.; Sims, Rebecca; Slimani, Nadia; Smith, Jennifer A.; Thompson, Deborah J.; Trompet, Stella; Tumino, Rosario; van der A, Daphne L.; van der Schouw, Yvonne T.; Virtamo, Jarmo; Walker, Mark; Walter, Klaudia; Abraham, Jean E.; Amundadottir, Laufey T.; Aponte, Jennifer L.; Butterworth, Adam S.; Dupuis, Josée; Easton, Douglas F.; Eeles, Rosalind A.; Erdmann, Jeanette; Franks, Paul W.; Frayling, Timothy M.; Hansen, Torben; Howson, Joanna M. M.; Jørgensen, Torben; Kooner, Jaspal; Laakso, Markku; Langenberg, Claudia; McCarthy, Mark I.; Pankow, James S.; Pedersen, Oluf; Riboli, Elio; Rotter, Jerome I.; Saleheen, Danish; Samani, Nilesh J.; Schunkert, Heribert; Vollenweider, Peter; O'Rahilly, Stephen; Deloukas, Panos; Danesh, John; Goodarzi, Mark O.; Kathiresan, Sekar; Meigs, James B.; Ehm, Margaret G.; Wareham, Nicholas J.; Waterworth, Dawn M.

    2016-01-01

    Regulatory authorities have indicated that new drugs to treat type 2 diabetes (T2D) should not be associated with an unacceptable increase in cardiovascular risk. Human genetics may be able to inform development of antidiabetic therapies by predicting cardiovascular and other health endpoints. We therefore investigated the association of variants in 6 genes that encode drug targets for obesity or T2D with a range of metabolic traits in up to 11,806 individuals by targeted exome sequencing, and follow-up in 39,979 individuals by targeted genotyping, with additional in silico follow up in consortia. We used these data to first compare associations of variants in genes encoding drug targets with the effects of pharmacological manipulation of those targets in clinical trials. We then tested the association those variants with disease outcomes, including coronary heart disease, to predict cardiovascular safety of these agents. A low-frequency missense variant (Ala316Thr;rs10305492) in the gene encoding glucagon-like peptide-1 receptor (GLP1R), the target of GLP1R agonists, was associated with lower fasting glucose and lower T2D risk, consistent with GLP1R agonist therapies. The minor allele was also associated with protection against heart disease, thus providing evidence that GLP1R agonists are not likely to be associated with an unacceptable increase in cardiovascular risk. Our results provide an encouraging signal that these agents may be associated with benefit, a question currently being addressed in randomised controlled trials. Genetic variants associated with metabolic traits and multiple disease outcomes can be used to validate therapeutic targets at an early stage in the drug development process. PMID:27252175

  20. GLP-1 Treatment Improves Diabetic Retinopathy by Alleviating Autophagy through GLP-1R-ERK1/2-HDAC6 Signaling Pathway.

    PubMed

    Cai, Xiangsheng; Li, Jingjing; Wang, Mingzhu; She, Miaoqin; Tang, Yongming; Li, Jinlong; Li, Hongwei; Hui, Hongxiang

    2017-01-01

    Objective: Apoptosis and autophagy of retinal cells, which may be induced by oxidative stress, are tightly associated with the pathogenesis of diabetic retinopathy (DR). The autophagy induced by oxidative stress is considered as excessively stimulated autophagy, which accelerates the progression of DR. This study aims to investigate the protective effect of GLP-1 treatment on alleviating apoptosis and autophagy of retinal cells in type 2 diabetic rats and reveals its possible mechanism. Methods: Type 2 diabetic rats were induced by fed with high sugar, high fat diet and followed with streptozotocin injection. GLP-1 was applied to treat the diabetic rats for one week after the onset of diabetes. The expressions of oxidative stress-related enzymes, retinal GLP-1R, mitochondria-dependent apoptosis- related genes, autophagy markers, and autophagy-associated pathway genes were studied by Western blotting or immunohistochemistry analysis. Results: GLP-1treatment reduced the levels of NOX3 and SOD2 in DR. The expression of BCL2 was increased, while the levels of caspase3 and LC3B were reduced through GLP-1 treatment in DR . GLP-1 treatment restored the GLP-1R expression and decreased the levels of phosphorylated AKT and phosphorylated ERK1/2, which was accompanied with the reduction of the HDAC6 levels in DR. Conclusions: GLP-1 treatment can alleviate autophagy which may be induced by oxidative stress; this protective effect is likely through GLP-1R-ERK1/2-HDAC6 signaling pathway.

  1. A surface plasmon resonance assay for characterisation and epitope mapping of anti-GLP-1 antibodies.

    PubMed

    Thomsen, Lasse; Gurevich, Leonid

    2018-04-19

    The incretin hormone glucagon-like peptide-1 (GLP-1) has been subject to substantial pharmaceutical research regarding the treatment of type 2 diabetes mellitus. However, quantification of GLP-1 levels remains complicated due to the low circulation concentration and concurrent existence of numerous metabolites, homologous peptides, and potentially introduced GLP-1 receptor agonists. Surface plasmon resonance (SPR) facilitates real-time monitoring allowing a more detailed characterisation of the interaction compared with conventional enzyme-linked immunosorbent assays (ELISA). In this paper, we describe the development of the first SPR assays for characterisation of anti-GLP-1 antibodies for ELISA purposes. Binding responses were obtained on covalently immobilised anti-GLP-1 antibodies at 12°C, 25°C, and 40°C and fitted to a biomolecular (1:1) interaction model showing association rates of 1.01 × 10 3 to 4.54 × 10 3  M -1  s -1 and dissociation rates of 3.56 × 10 -5 to 1.56 × 10 -3  s -1 leading to affinities of 35.2 to 344 nM, depending on the temperature. Determination of thermodynamic properties revealed an enthalpy driven interaction (ΔH < ΔS < 0) with higher affinities at lower temperatures due to the formation and stabilisation of hydrogen bonds within the binding site primarily composed of polar amino acids (ΔC p  < 0). Pair-wise epitope mapping was performed on captured anti-GLP-1 antibodies followed by subsequent interaction with GLP-1 (7-36) and other anti-GLP-1 antibodies. A global evaluation of every binding response led to an epitope map elucidating the potential of various anti-GLP-1 antibody pairs for sandwich ELISA and hence pinpointing the optimal antibody combinations. The SPR assays proved capable of providing vital information for ELISA development endorsing it as a useful optimisation tool. Copyright © 2018 John Wiley & Sons, Ltd.

  2. Myricetin: a potent approach for the treatment of type 2 diabetes as a natural class B GPCR agonist

    PubMed Central

    Li, Ying; Zheng, Xuemin; Yi, Xiulin; Liu, Changxiao; Kong, Dexin; Zhang, Jianning; Gong, Min

    2017-01-01

    The physiologic properties of glucagon-like peptide 1 (GLP-1) make it a potent candidate drug target in the treatment of type 2 diabetes mellitus (T2DM). GLP-1 is capable of regulating the blood glucose level by insulin secretion after administration of oral glucose. The advantages of GLP-1 for the avoidance of hypoglycemia and the control of body weight are attractive despite its poor stability. The clinical efficacies of long-acting GLP-1 derivatives strongly support discovery pursuits aimed at identifying and developing orally active, small-molecule GLP-1 receptor (GLP-1R) agonists. The purpose of this study was to identify and characterize a novel oral agonist of GLP-1R (i.e., myricetin). The insulinotropic characterization of myricetin was performed in isolated islets and in Wistar rats. Long-term oral administration of myricetin demonstrated glucoregulatory activity. The data in this study suggest that myricetin might be a potential drug candidate for the treatment of T2DM as a GLP-1R agonist. Further structural modifications on myricetin might improve its pharmacology and pharmacokinetics.—Li, Y., Zheng, X., Yi, X., Liu, C., Kong, D., Zhang, J., Gong, M. Myricetin: a potent approach for the treatment of type 2 diabetes as a natural class B GPCR agonist. PMID:28270518

  3. Glucagon like peptide-1 and its receptor agonists: Their roles in management of Type 2 diabetes mellitus.

    PubMed

    Gupta, Ankit; Jelinek, Herbert F; Al-Aubaidy, Hayder

    This study summarizes major work which investigated the roles of glucagon like peptide-1 (GLP-1) and its receptor (GLP-1R); the use of GLP-1-R agonists and dipeptidyl peptidase 4 inhibitor in the management of type 2 diabetes mellitus. It focuses on the recent therapeutic development which has occurred in this field, and also discusses the potential treatments which can be discovered and implemented in the near future to design an effective therapy for type 2 diabetes mellitus. Copyright © 2016 Diabetes India. Published by Elsevier Ltd. All rights reserved.

  4. The Aversive Agent Lithium Chloride Suppresses Phasic Dopamine Release Through Central GLP-1 Receptors.

    PubMed

    Fortin, Samantha M; Chartoff, Elena H; Roitman, Mitchell F

    2016-02-01

    Unconditioned rewarding stimuli evoke phasic increases in dopamine concentration in the nucleus accumbens (NAc) while discrete aversive stimuli elicit pauses in dopamine neuron firing and reductions in NAc dopamine concentration. The unconditioned effects of more prolonged aversive states on dopamine release dynamics are not well understood and are investigated here using the malaise-inducing agent lithium chloride (LiCl). We used fast-scan cyclic voltammetry to measure phasic increases in NAc dopamine resulting from electrical stimulation of dopamine cell bodies in the ventral tegmental area (VTA). Systemic LiCl injection reduced electrically evoked dopamine release in the NAc of both anesthetized and awake rats. As some behavioral effects of LiCl appear to be mediated through glucagon-like peptide-1 receptor (GLP-1R) activation, we hypothesized that the suppression of phasic dopamine by LiCl is GLP-1R dependent. Indeed, peripheral pretreatment with the GLP-1R antagonist exendin-9 (Ex-9) potently attenuated the LiCl-induced suppression of dopamine. Pretreatment with Ex-9 did not, however, affect the suppression of phasic dopamine release by the kappa-opioid receptor agonist, salvinorin A, supporting a selective effect of GLP-1R stimulation in LiCl-induced dopamine suppression. By delivering Ex-9 to either the lateral or fourth ventricle, we highlight a population of central GLP-1 receptors rostral to the hindbrain that are involved in the LiCl-mediated suppression of NAc dopamine release.

  5. Differential structural properties of GLP-1 and exendin-4 determine their relative affinity for the GLP-1 receptor N-terminal extracellular domain.

    PubMed

    Runge, Steffen; Schimmer, Susann; Oschmann, Jan; Schiødt, Christine Bruun; Knudsen, Sanne Möller; Jeppesen, Claus Bekker; Madsen, Kjeld; Lau, Jesper; Thøgersen, Henning; Rudolph, Rainer

    2007-05-15

    Glucagon-like peptide-1 (GLP-1) and exendin-4 (Ex4) are homologous peptides with established potential for treatment of type 2 diabetes. They bind and activate the pancreatic GLP-1 receptor (GLP-1R) with similar affinity and potency and thereby promote insulin secretion in a glucose-dependent manner. GLP-1R belongs to family B of the seven transmembrane G-protein coupled receptors. The N-terminal extracellular domain (nGLP-1R) is a ligand binding domain with differential affinity for Ex4 and GLP-1: low affinity for GLP-1 and high affinity for exendin-4. The superior affinity of nGLP-1R for Ex4 was previously explained by an additional interaction between nGLP-1R and the C-terminal Trp-cage of Ex4. In this study we have combined biophysical and pharmacological approaches thus relating structural properties of the ligands in solution to their relative binding affinity for nGLP-1R. We used both a tracer competition assay and ligand-induced thermal stabilization of nGLP-1R to measure the relative affinity of full length, truncated, and chimeric ligands for soluble refolded nGLP-1R. The ligands in solution and the conformational consequences of ligand binding to nGLP-1R were characterized by circular dichroism and fluorescence spectroscopy. We found a correlation between the helical content of the free ligands and their relative binding affinity for nGLP-1R, supporting the hypothesis that the ligands are helical at least in the segment that binds to nGLP-1R. The Trp-cage of Ex4 was not necessary to maintain a superior helicity of Ex4 compared to GLP-1. The results suggest that the differential affinity of nGLP-1R is explained almost entirely by divergent residues in the central part of the ligands: Leu10-Gly30 of Ex4 and Val16-Arg36 of GLP-1. In view of our results it appears that the Trp-cage plays only a minor role for the interaction between Ex4 and nGLP-1R and for the differential affinity of nGLP-1R for GLP-1 and Ex4.

  6. Expression of CTRP3, a Novel Adipokine, in Rats at Different Pathogenic Stages of Type 2 Diabetes Mellitus and the Impacts of GLP-1 Receptor Agonist on It

    PubMed Central

    Li, Xin; Jiang, Li; Yang, Miao; Wu, Yu-wen; Sun, Su-xin; Sun, Jia-zhong

    2014-01-01

    This study aimed to investigate the expression of C1q/TNF-related protein-3 (CTRP3) in rats at different pathogenic stages of type 2 diabetes mellitus (T2DM) and the impacts of glucagon-like peptide-1 (GLP-1) receptor agonist on it. Male wistar rats were fed with high-fat diet for 10 weeks to induce insulin resistance (IR) and then were given low-dose streptozotocin (STZ) intraperitoneal injection to induce T2DM. Exendin-4 (Ex-4), a GLP-1 receptor agonist, was subcutaneous injected to the IR rats and T2DM rats for 4 weeks. The expression of CTRP3 mRNA and protein in epididymis adipose tissue of rats at the stage of IR was lower significantly than that of normal control (NC) rats and decreased more when they were at the stage of overt T2DM (all P < 0.05 or P < 0.01). After the treatment with Ex-4, the mRNA and protein expressions of CTRP3 were increased by 15.5% (P < 0.01) and 14.8% (P < 0.05), respectively, in IR rats and increased by 20.6% (P < 0.01) and 16.5% (P < 0.05), respectively, in T2DM rats. Overall, this study found that the expression of CTRP3 in visceral adipose tissue was progressively decreased in a T2DM rat model from the pathogenic stage of IR to overt diabetes, while Ex-4 treatment increased its expression in such animals. PMID:25177707

  7. GLP-1 secretion is stimulated by 1,10-phenanthroline via colocalized T2R5 signal transduction in human enteroendocrine L cell

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Park, Jiyoung; Kim, Ki-Suk; Kim, Kang-Hoon

    Glucagon-like peptide-1 (GLP-1) hormone is known to regulate blood glucose by an insulinotropic effect and increases proliferation as and also prevents apoptosis of pancreatic β cells. We know that GLP-1 is secreted by nutrients such as fatty acids and sweet compounds but also bitter compounds via stimulation of G-protein coupled receptors (GPCRs) in the gut. Among these, bitter compounds are multiply-contained in phytochemicals or artificial materials and perceived as ligands of various bitter taste receptors. We hypothesized that GLP-1 hormone is secreted through stimulation of a single bitter taste receptor by 1,10-phenanthroline which is known agonist of taste receptor typemore » 2 member 5 (T2R5). To prove this hypothesis, we used the representatively well-known 1,10-phenanthroline as ligand of single receptor and evaluated the existence of T2R5 by double-labeling immunofluorescence and then 1,10-phenanthroline is able to secrete GLP-1 hormone through stimulation of T2R5 in human enteroendocrine cells. Consequently, we verify that GLP-1 hormone is colocalized with T2R5 in the human duodenum and ileum tissue and is secreted by 1,10-phenanthroline via T2R5 signal transduction in differentiated human enteroendocrine L cells. - Highlights: • Taste receptor type 2 member 5 (T2R5) is colocalized with GLP-1 hormone in human enteroendocrine cells. • GLP-1 secretion is stimulated by 1,10-phenanthroline via stimulation of T2R5. • Inhibition of the bitter taste pathway reduce GLP-1 secretion.« less

  8. Novel selective agonists and antagonists confirm neurokinin NK1 receptors in guinea-pig vas deferens.

    PubMed Central

    Hall, J. M.; Morton, I. K.

    1991-01-01

    1. This study investigated the recognition characteristics of neurokinin receptors mediating potentiation of the contractile response to field stimulation in the guinea-pig vas deferens. 2. A predominant NK1 receptor population is strongly suggested by the relative activities of the common naturally-occurring tachykinin agonists, which fall within less than one order of magnitude. This conclusion is supported by the relative activities of the synthetic NK1 selective agonists substance P methyl ester, [Glp6,L-Pro9]-SP(6-11) and delta-aminovaleryl-[L-Pro9,N-MeLeu10]- SP(7-11) (GR73632) which were 0.78, 9.3 and 120 as active as substance P, respectively. Furthermore, the NK2 selective agonist [Lys3, Gly8,-R-gamma-lactam-Leu9]-NKA(3-10) (GR64349) was active only at the highest concentrations tested (greater than 10 microM), and the NK3 selective agonist, succ-[Asp6,N-MePhe8]-SP(6-11) (senktide) was essentially inactive (10 nM-32 microM). 3. [D-Arg1,D-Pro2,D-Trp7,9,Leu11]-SP(1-11) antagonized responses to neurokinin A, neurokinin B, physalaemin, eledoisin, [Glp6,D-Pro9]-SP(6-11), GR73632 and GR64349 (apparent pKB s 5.6-6.2), but was less potent in antagonizing responses to substance P, substance P methyl ester and [Glp6,L-Pro9]-SP(6-11) (apparent pKB s less than or equal to 5.0-5.0). 4. In contrast, the recently developed NK1-selective receptor antagonist [D-Pro9[Spiro-gamma-lactam]Leu10,Trp11]-SP(1-11) (GR71251) did not produce agonist-dependent pKB estimates. Schild plot analysis indicated a competitive interaction with a single receptor population where the antagonist had an estimated overall pKB of 7.58 +/- 0.13 for the four agonists of differing subtype selectivity tested (GR73632, GR64349, substance P methyl ester and neurokinin B).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1707714

  9. GLP-1-Based Therapies Have No Microvascular Effects in Type 2 Diabetes Mellitus: An Acute and 12-Week Randomized, Double-Blind, Placebo-Controlled Trial.

    PubMed

    Smits, Mark M; Tonneijck, Lennart; Muskiet, Marcel H A; Hoekstra, Trynke; Kramer, Mark H H; Diamant, Michaela; Serné, Erik H; van Raalte, Daniël H

    2016-10-01

    To assess the effects of glucagon-like peptide (GLP)-1-based therapies (ie, GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors) on microvascular function in patients with type 2 diabetes mellitus. We studied 57 patients with type 2 diabetes mellitus (mean±SD age: 62.8±6.9 years; body mass index: 31.8±4.1 kg/m(2); HbA1c [glycated hemoglobin] 7.3±0.6%) in an acute and 12-week randomized, placebo-controlled, double-blind trial conducted at the Diabetes Center of the VU University Medical Center. In the acute study, the GLP-1 receptor agonist exenatide (therapeutic concentrations) or placebo (saline 0.9%) was administered intravenously. During the 12-week study, patients received the GLP-1 receptor agonist liraglutide (1.8 mg daily), the dipeptidyl peptidase-4 inhibitor sitagliptin (100 mg daily), or matching placebos. Capillary perfusion was assessed by nailfold skin capillary videomicroscopy and vasomotion by laser Doppler fluxmetry, in the fasting state and after a high-fat mixed meal. In neither study, treatment affected fasting or postprandial capillary perfusion compared with placebo (P>0.05). In the fasting state, acute exenatide infusion increased neurogenic vasomotion domain power, while reducing myogenic domain power (both P<0.05). After the meal, exenatide increased endothelial domain power (P<0.05). In the 12-week study, no effects on vasomotion were observed. Despite modest changes in vasomotion, suggestive of sympathetic nervous system activation and improved endothelial function, acute exenatide infusion does not affect skin capillary perfusion in type 2 diabetes mellitus. Twelve-week treatment with liraglutide or sitagliptin has no effect on capillary perfusion or vasomotion in these patients. Our data suggest that the effects of GLP-1-based therapies on glucose are not mediated through microvascular responses. © 2016 American Heart Association, Inc.

  10. A Targeted RNAi Screen Identifies Endocytic Trafficking Factors That Control GLP-1 Receptor Signaling in Pancreatic β-Cells.

    PubMed

    Buenaventura, Teresa; Kanda, Nisha; Douzenis, Phoebe C; Jones, Ben; Bloom, Stephen R; Chabosseau, Pauline; Corrêa, Ivan R; Bosco, Domenico; Piemonti, Lorenzo; Marchetti, Piero; Johnson, Paul R; Shapiro, A M James; Rutter, Guy A; Tomas, Alejandra

    2018-03-01

    The glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) is a key target for type 2 diabetes (T2D) treatment. Because endocytic trafficking of agonist-bound receptors is one of the most important routes for regulation of receptor signaling, a better understanding of this process may facilitate the development of new T2D therapeutic strategies. Here, we screened 29 proteins with known functions in G protein-coupled receptor trafficking for their role in GLP-1R potentiation of insulin secretion in pancreatic β-cells. We identify five (clathrin, dynamin1, AP2, sorting nexins [SNX] SNX27, and SNX1) that increase and four (huntingtin-interacting protein 1 [HIP1], HIP14, GASP-1, and Nedd4) that decrease insulin secretion from murine insulinoma MIN6B1 cells in response to the GLP-1 analog exendin-4. The roles of HIP1 and the endosomal SNX1 and SNX27 were further characterized in mouse and human β-cell lines and human islets. While HIP1 was required for the coupling of cell surface GLP-1R activation with clathrin-dependent endocytosis, the SNXs were found to control the balance between GLP-1R plasma membrane recycling and lysosomal degradation and, in doing so, determine the overall β-cell incretin responses. We thus identify key modulators of GLP-1R trafficking and signaling that might provide novel targets to enhance insulin secretion in T2D. © 2017 by the American Diabetes Association.

  11. Central GLP-1 receptor activation modulates cocaine-evoked phasic dopamine signaling in the nucleus accumbens core.

    PubMed

    Fortin, Samantha M; Roitman, Mitchell F

    2017-07-01

    Drugs of abuse increase the frequency and magnitude of brief (1-3s), high concentration (phasic) dopamine release events in terminal regions. These are thought to be a critical part of drug reinforcement and ultimately the development of addiction. Recently, metabolic regulatory peptides, including the satiety signal glucagon-like peptide-1 (GLP-1), have been shown to modulate cocaine reward-driven behavior and sustained dopamine levels after cocaine administration. Here, we use fast-scan cyclic voltammetry (FSCV) to explore GLP-1 receptor (GLP-1R) modulation of dynamic dopamine release in the nucleus accumbens (NAc) during cocaine administration. We analyzed dopamine release events in both the NAc shell and core, as these two subregions are differentially affected by cocaine and uniquely contribute to motivated behavior. We found that central delivery of the GLP-1R agonist Exendin-4 suppressed the induction of phasic dopamine release events by intravenous cocaine. This effect was selective for dopamine signaling in the NAc core. Suppression of phasic signaling in the core by Exendin-4 could not be attributed to interference with cocaine binding to one of its major substrates, the dopamine transporter, as cocaine-induced increases in reuptake were unaffected. The results suggest that GLP-1R activation, instead, exerts its suppressive effects by altering dopamine release - possibly by suppressing the excitability of dopamine neurons. Given the role of NAc core dopamine in the generation of conditioned responses based on associative learning, suppression of cocaine-induced dopamine signaling in this subregion by GLP-1R agonism may decrease the reinforcing properties of cocaine. Thus, GLP-1Rs remain viable targets for the treatment and prevention of cocaine seeking, taking and relapse. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Glucagon-like peptide-1 receptor agonists compared with basal insulins for the treatment of type 2 diabetes mellitus: a systematic review and meta-analysis.

    PubMed

    Singh, Sonal; Wright, Eugene E; Kwan, Anita Y M; Thompson, Juliette C; Syed, Iqra A; Korol, Ellen E; Waser, Nathalie A; Yu, Maria B; Juneja, Rattan

    2017-02-01

    Since 2005, several glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have been approved to treat people with type 2 diabetes. These agents are considered for use at the same point in the treatment paradigm as basal insulins. A comprehensive comparison of these drug classes, therefore, can help inform treatment decisions. This systematic review and meta-analysis assessed the clinical efficacy and safety of GLP-1 RAs compared with basal insulins. MEDLINE, EMBASE, CENTRAL and PubMed databases were searched. Randomized clinical trials (RCTs) of ≥16 weeks' duration comparing GLP-1 RAs vs basal insulins in adults with type 2 diabetes inadequately controlled with oral antihyperglycemic drugs were included. Data on the change from baseline to 26 weeks (±10 weeks) of treatment in hemoglobin A1c (HbA1c) and weight, as well as the proportion of patients experiencing hypoglycaemia, were extracted. Fixed-effect pairwise meta-analyses were conducted where data were available from ≥2 studies. Fifteen RCTs were identified and 11 were meta-analysed. The once-weekly GLP-1 RAs, exenatide long acting release (LAR) and dulaglutide, led to greater, statistically significant mean HbA1c reductions vs basal insulins (exenatide: -0.31% [95% confidence interval -0.42, -0.19], dulaglutide: -0.39% [-0.49, -0.29]) whilst once-daily liraglutide and twice-daily exenatide did not (liraglutide: 0.06% [-0.06, 0.18], exenatide: 0.01% [-0.11, 0.13]). Mean weight reduction was seen with all GLP-1 RAs while mean weight gain was seen with basal insulins. Interpretation of the analysis of hypoglycaemia was limited by inconsistent definitions and reporting. Because of the limited number of available studies sensitivity analyses to explore heterogeneity could not be conducted. Although weight reduction is seen with all GLP-1 RA's, only the once-weekly agents, exenatide LAR and dulaglutide, demonstrate significant HbA1c reductions when compared to basal insulins. © 2016 The Authors. Diabetes

  13. Treatment of antipsychotic-associated obesity with a GLP-1 receptor agonist--protocol for an investigator-initiated prospective, randomised, placebo-controlled, double-blinded intervention study: the TAO study protocol.

    PubMed

    Ishøy, Pelle L; Knop, Filip K; Broberg, Brian V; Baandrup, Lone; Fagerlund, Birgitte; Jørgensen, Niklas R; Andersen, Ulrik B; Rostrup, Egill; Glenthøj, Birte Y; Ebdrup, Bjørn H

    2014-01-08

    Antipsychotic medication is widely associated with dysmetabolism including obesity and type 2 diabetes, cardiovascular-related diseases and early death. Obesity is considered the single most important risk factor for cardiovascular morbidity and mortality. Interventions against antipsychotic-associated obesity are limited and insufficient. Glucagon-like peptide-1 (GLP-1) receptor agonists are approved for the treatment of type 2 diabetes, but their bodyweight-lowering effects have also been recognised in patients with non-diabetes. The primary endpoint of this trial is weight loss after 3 months of treatment with a GLP-1 receptor agonist (exenatide once weekly) in patients with non-diabetic schizophrenia with antipsychotic-associated obesity. Secondary endpoints include physiological and metabolic measurements, various psychopathological and cognitive measures, and structural and functional brain MRI. 40 obese patients with schizophrenia or schizoaffective disorder treated with antipsychotic drugs will be randomised to subcutaneous injection of exenatide once weekly (2 mg) or placebo for 3 months, adjunctive to their antipsychotic treatment. The trial has been approved by the Danish Health and Medicines Authority, the National Committee on Health Research Ethics and the Danish Data Protection Agency. Trial participation presupposes theoral and written patient informed consent. An external, independent monitoring committee (Good Clinical Practice Unit at Copenhagen University Hospital) will monitor the study according to the GCP Guidelines. Trial data, including positive, negative and inconclusive results, will be presented at national and international scientific meetings and conferences. Papers will be submitted to peer-reviewed journals. ClinicalTrials.gov identifier: NCT01794429; National Committee on Health Research Ethics project number: 36378; EudraCT nr: 2012-005404-17; The Danish Data Protection Agency project number: RHP-2012-027.

  14. Effects of gastric inhibitory polypeptide, glucagon-like peptide-1 and glucagon-like peptide-1 receptor agonists on Bone Cell Metabolism.

    PubMed

    Hansen, Morten S S; Tencerova, Michaela; Frølich, Jacob; Kassem, Moustapha; Frost, Morten

    2018-01-01

    The relationship between gut and skeleton is increasingly recognized as part of the integrated physiology of the whole organism. The incretin hormones gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are secreted from the intestine in response to nutrient intake and exhibit several physiological functions including regulation of islet hormone secretion and glucose levels. A number of GLP-1 receptor agonists (GLP-1RAs) are currently used in treatment of type 2 diabetes and obesity. However, GIP and GLP-1 cognate receptors are widely expressed suggesting that incretin hormones mediate effects beyond control of glucose homeostasis, and reports on associations between incretin hormones and bone metabolism have emerged. The aim of this MiniReview was to provide an overview of current knowledge regarding the in vivo and in vitro effects of GIP and GLP-1 on bone metabolism. We identified a total of 30 pre-clinical and clinical investigations of the effects of GIP, GLP-1 and GLP-1RAs on bone turnover markers, bone mineral density (BMD), bone microarchitecture and fracture risk. Studies conducted in cell cultures and rodents demonstrated that GIP and GLP-1 play a role in regulating skeletal homeostasis, with pre-clinical data suggesting that GIP inhibits bone resorption whereas GLP-1 may promote bone formation and enhance bone material properties. These effects are not corroborated by clinical studies. While there is evidence of effects of GIP and GLP-1 on bone metabolism in pre-clinical investigations, clinical trials are needed to clarify whether similar effects are present and clinically relevant in humans. © 2017 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  15. Update in Cardiovascular Safety of Glucagon Like Peptide-1 Receptor Agonists In Patients With Type 2 Diabetes. A Mixed Treatment Comparison Meta-Analysis of Randomised Controlled Trials.

    PubMed

    Al Yami, Majed S; Alfayez, Osamah M; Alsheikh, Razan

    2018-03-29

    The aim of this mixed treatment comparison (MTC) meta-analysis was to determine glucagon like peptide-1 (GLP-1) receptor agonists' effects on cardiovascular (CV) outcomes in patients with type 2 diabetes (T2DM). A comprehensive, systematic review was conducted using EMBASE and Medline databases. All included trials were large CV outcome trials of GLP-1 agonists versus placebo in T2DM. The primary outcomes of this MTC meta-analysis were death from CV causes, non-fatal MI, and non-fatal stroke. Hospitalisation for heart failure (HF) was evaluated as a secondary endpoint. A total of four trials, including 33,457 patients, met eligibility criteria and were retained for the meta-analysis. Our pairwise meta-analysis results showed a 13% reduction in death from cardiovascular causes in patients who received GLP-1 agonists versus placebo (RR 0.87, 95% CI: 0.78-0.96). However, no statistically significant reduction was observed with GLP-1 agonists in terms of reducing non-fatal MI (RR 0.95, 95% CI: 0.86-1.04), non-fatal stroke events (RR 0.89, 95% CI: 0.76-1.03), and rates of HF hospitalisation (RR 0.94, 95% CI: 0.84-1.04). The network meta-analysis (NMA) showed no significant differences among all the interventions. Glucagon like peptide-1 therapy was associated with a significant reduction in cardiovascular (CV) death. However, GLP-1 agonists seem to have a safety profile comparable to placebo in terms of reducing non-fatal myocardial infarction (MI), non-fatal stroke events, and rates of HF hospitalisation. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  16. Mody-3: novel HNF1A mutation and the utility of glucagon-like peptide (GLP)-1 receptor agonist therapy.

    PubMed

    Docena, Maricor K; Faiman, Charles; Stanley, Christine M; Pantalone, Kevin M

    2014-02-01

    An estimated 1 to 2% of cases of diabetes mellitus have a monogenic basis; however, delayed diagnosis and misdiagnosis as type 1 and 2 diabetes are common. Correctly identifying the molecular basis of an individual's diabetes may significantly alter the management approach to both the patient and his or her relatives. We describe a case of mature onset diabetes of the young (MODY) with sufficient evidence to support the classification of a novel HNF1A (hepatocyte nuclear factor-1-α) mutation as a cause of MODY-3. A 21-year-old Caucasian female presented to our office with a diagnosis of noninsulin-dependent diabetes mellitus (NIDDM) at age 10; glycemia was initially managed with oral antidiabetic (OAD) agents and insulin detemir. The patient reported a strong family history of early-onset NIDDM in both her mother and maternal grandmother, both of whom eventually required insulin therapy to control glycemia. The patient's medical and family history were highly suggestive of maturity-onset diabetes of the young (MODY), and genetic testing was performed. Genetic screening detected a mutation p. Arg200Trp in the HNF1A gene in the patient, her mother, and maternal grandmother, suggesting a diagnosis of MODY-3. This finding resulted in a change of antidiabetic therapy in all 3 patients, including the addition of once-daily liraglutide therapy, which helped improve their glycemic control. Our case report supports the classification of the p. Arg200Trp mutation as a cause of MODY-3. The findings also suggest that glucagon-like peptide-1 (GLP-1) receptor agonist therapy may be of value in managing glycemia in patients with MODY-3.

  17. Short-acting glucagon-like peptide-1 receptor agonists as add-on to insulin therapy in type 1 diabetes: A review.

    PubMed

    Albèr, Anders; Brønden, Andreas; Knop, Filip K

    2017-07-01

    A large proportion of patients with type 1 diabetes do not reach their glycaemic target of glycated hemoglobin (HbA1c) <7.0% (53 mmol/mol) and, furthermore, an increasing number of patients with type 1 diabetes are overweight and obese. Treatment of type 1 diabetes is based on insulin therapy, which is associated with well-described and unfortunate adverse effects such as hypoglycaemia and increased body weight. Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are the focus of increasing interest as a possible adjunctive treatment to insulin in type 1 diabetes because of their glucagonostatic and extrapancreatic effects. So far, the focus has mainly been on the long-acting GLP-1RAs, but the risk-benefit ratio emerging from studies evaluating the effect of long-acting GLP-1RAs as adjunctive therapy to insulin therapy in patients with type 1 diabetes has been disappointing. This might be attributable to a lack of glucagonostatic effect of these long-acting GLP-1RAs in type 1 diabetes, alongside development of tachyphylaxis to GLP-1-induced retardation of gastric emptying. In contrast, the short-acting GLP-1RAs seem to have a preserved and sustained effect on glucagon secretion and gastric emptying in patients with type 1 diabetes, which could translate into effective lowering of postprandial glucose excursions; however, these observations regarding short-acting GLP-1RAs are all derived from small open-label trials and should thus be interpreted with caution. In the present paper we review the potential role of GLP-1RAs, in particular short-acting GLP-1RAs, as add-on to insulin in the treatment of type 1 diabetes. © 2017 John Wiley & Sons Ltd.

  18. Activation of PPARβ/δ protects pancreatic β cells from palmitate-induced apoptosis by upregulating the expression of GLP-1 receptor.

    PubMed

    Yang, Yan; Tong, Yuzhen; Gong, Meng; Lu, Yanrong; Wang, Chengshi; Zhou, Mingliang; Yang, Qiu; Mao, Tingrui; Tong, Nanwei

    2014-02-01

    We previously showed that activated peroxisome proliferator-activated receptor (PPAR)β/δ can protect pancreatic β cells against lipotoxic apoptosis. However, the molecular mechanism remained unclear. Glucagon-like peptide-1 receptor (GLP-1R) has been reported to exhibit a protective effect against lipotoxic apoptosis in pancreatic β cells. In the present study, we aimed to investigate the underlying molecular mechanisms that PPARβ/δ activation suppressed apoptosis and improved β cell function impaired by fatty acids, focusing on contribution of GLP-1R. Isolated rat islets and rat insulin-secreting INS-1 cells were treated with the PPARβ/δ agonist GW501516 (GW) in the presence or absence of palmitate (PA) and transfected with siRNA for PPARβ/δ or treated with the PPARβ/δ antagonist GSK0660. Apoptosis was assessed by DNA fragmentation, Hoechst 33342 staining and flow cytometry. GLP-1R expression in INS-1 cells and islets was assayed by immunoblotting, quantitative PCR (qPCR) and immunofluorescence staining. SREBP-1c, Caveolin-1, Akt, Bcl-2, Bcl-xl and caspase-3 expression was measured using immunoblotting and qPCR. Our results showed that PPARβ/δ activation decreased apoptosis in β cells and robustly stimulated GLP-1R expression under lipotoxic conditions. GW enhanced glucose-stimulated insulin secretion (GSIS) impaired by PA through stimulation of GLP-1R expression in β cells. Moreover, SREBP-1c/Caveolin-1 signaling was involved in PPARβ/δ-regulated GLP-1R expression. Finally, GW exerted anti-apoptotic effects via interfering with GLP-1R-dependent Akt/Bcl-2 and Bcl-xl/caspase-3 signaling pathways. Our study suggested that the anti-apoptotic action of GW may involve its transcriptional regulation of GLP-1R, and PPARβ/δ activation may represent a new therapeutic method for protecting pancreatic β cells from lipotoxicity. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. FFA3 Activation Stimulates Duodenal Bicarbonate Secretion and Prevents NSAID-Induced Enteropathy via the GLP-2 Pathway in Rats.

    PubMed

    Said, Hyder; Akiba, Yasutada; Narimatsu, Kazuyuki; Maruta, Koji; Kuri, Ayaka; Iwamoto, Ken-Ichi; Kuwahara, Atsukazu; Kaunitz, Jonathan D

    2017-08-01

    Therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with enteropathy in humans and experimental animals, a cause of considerable morbidity. Unlike foregut NSAID-associated mucosal lesions, most treatments for this condition are of little efficacy. We propose that the endogenously released intestinotrophic hormone glucagon-like peptide-2 (GLP-2) prevents the development of NSAID-induced enteropathy. Since the short-chain fatty acid receptor FFA3 is expressed on enteroendocrine L cells and on enteric nerves in the gastrointestinal tract, we further hypothesized that activation of FFA3 on L cells protects the mucosa from injury via GLP-2 release with enhanced duodenal HCO 3 - secretion. We thus investigated the effects of synthetic selective FFA3 agonists with consequent GLP-2 release on NSAID-induced enteropathy. We measured duodenal HCO 3 - secretion in isoflurane-anesthetized rats in a duodenal loop perfused with the selective FFA3 agonists MQC or AR420626 (AR) while measuring released GLP-2 in the portal vein (PV). Intestinal injury was produced by indomethacin (IND, 10 mg/kg, sc) with or without MQC (1-10 mg/kg, ig) or AR (0.01-0.1 mg/kg, ig or ip) treatment. Luminal perfusion with MQC or AR (0.1-10 µM) dose-dependently augmented duodenal HCO 3 - secretion accompanied by increased GLP-2 concentrations in the PV. The effect of FFA3 agonists was inhibited by co-perfusion of the selective FFA3 antagonist CF3-MQC (30 µM). AR-induced augmented HCO 3 - secretion was reduced by iv injection of the GLP-2 receptor antagonist GLP-2(3-33) (3 nmol/kg), or by pretreatment with the cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor CFTR inh -172 (1 mg/kg, ip). IND-induced small intestinal ulcers were dose-dependently inhibited by intragastric administration of MQC or AR. GLP-2(3-33) (1 mg/kg, ip) or CF3-MQC (1 mg/kg, ig) reversed AR-associated reduction in IND-induced enteropathy. In contrast, ip injection of AR had no effect

  20. The endocrine disrupting potential of monosodium glutamate (MSG) on secretion of the glucagon-like peptide-1 (GLP-1) gut hormone and GLP-1 receptor interaction.

    PubMed

    Shannon, Maeve; Green, Brian; Willars, Gary; Wilson, Jodie; Matthews, Natalie; Lamb, Joanna; Gillespie, Anna; Connolly, Lisa

    2017-01-04

    Monosodium glutamate (MSG) is a suspected obesogen with epidemiological evidence positively correlating consumption to increased body mass index and higher prevalence of metabolic syndrome. ELISA and high content analysis (HCA) were employed to examine the disruptive effects of MSG on the secretion of enteroendocrine hormone glucagon-like peptide-1 (GLP-1) and GLP-1 receptor (GLP-1R), respectively. Following 3h MSG exposure of the enteroendocrine pGIP/neo: STC-1 cell line model (500μg/ml) significantly increased GLP-1 secretion (1.8 fold; P≤0.001), however, 72h exposure (500μg/ml) caused a 1.8 fold decline (P≤0.05). Also, 3h MSG exposure (0.5-500μg/ml) did not induce any cytotoxicity (including multiple pre-lethal markers) but 72h exposure at 250-500μg/ml, decreased cell number (11.8-26.7%; P≤0.05), increased nuclear area (23.9-29.8%; P≤0.001) and decreased mitochondrial membrane potential (13-21.6%; P≤0.05). At 500μg/ml, MSG increased mitochondrial mass by 16.3% (P≤0.01). MSG did not agonise or antagonise internalisation of the GLP-1R expressed recombinantly in U2OS cells, following GLP-1 stimulation. In conclusion, 72h exposure of an enteroendocrine cell line at dietary levels of MSG, results in pre-lethal cytotoxicity and decline in GLP-1 secretion. These adverse events may play a role in the pathogenesis of obesity as outlined in the obesogen hypothesis by impairing GLP-1 secretion, related satiety responses and glucose-stimulated insulin release. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  1. Glucagon-like peptide-1 receptor agonists versus insulin glargine for type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

    PubMed Central

    Li, Wei-Xin; Gou, Jian-Feng; Tian, Jin-Hui; Yan, Xiang; Yang, Lin

    2010-01-01

    Background: Glucagon-like peptide-1 (GLP-1) receptor agonists are a new class of hypoglycemic drugs, including exenatide, liraglutide, albiglutide, lixisenatide, and taspoglutide. Insulin glargine is a standard agent used to supplement basal insulin in type 2 diabetes mellitus (T2DM). Objective: The aim of this study was to review the efficacy and safety profiles of GLP-1 receptor agonists versus insulin glargine in type 2 diabetic patients who have not achieved treatment goals with oral hypoglycemic agents. Methods: The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and the database of ongoing trials were searched from inception through April 2010. Additional data were sought from relevant Web sites, the American Diabetes Association, reference lists of included trials and related (systematic) reviews, and industry. Randomized controlled trials (RCTs) were selected if they were ≥3 months in duration, compared GLP-1 receptor agonists with insulin glargine in patients with T2DM, and included ≥1 of the following outcomes: mortality, complications of T2DM, glycemie control, weight, lipids, blood pressure, adverse effects, and health-related quality of life. Quasirandomized controlled trials were excluded. The quality of the eligible studies was assessed on the basis of the following aspects: randomization procedure, allocation concealment, blinding, incomplete outcome data (intent-to-treat [ITT] analysis), selective outcome reporting, and publication bias. Results: A total of 410 citations were retrieved; 5 multicenter RCTs that met the inclusion criteria were identified. They were all open-label designs with an insulin glargine arm, predefined outcomes reported, and ITT analysis. One trial had an unclear randomization procedure and allocation concealment. Publication bias was not able to be determined. No data wete found with regard to mortality or diabetes-associated complications, and few data were found on quality of life. The results of

  2. GLP-1 acts on habenular avoidance circuits to control nicotine intake.

    PubMed

    Tuesta, Luis M; Chen, Zuxin; Duncan, Alexander; Fowler, Christie D; Ishikawa, Masago; Lee, Brian R; Liu, Xin-An; Lu, Qun; Cameron, Michael; Hayes, Matthew R; Kamenecka, Theodore M; Pletcher, Matthew; Kenny, Paul J

    2017-05-01

    Tobacco smokers titrate their nicotine intake to avoid its noxious effects, sensitivity to which may influence vulnerability to tobacco dependence, yet mechanisms of nicotine avoidance are poorly understood. Here we show that nicotine activates glucagon-like peptide-1 (GLP-1) neurons in the nucleus tractus solitarius (NTS). The antidiabetic drugs sitagliptin and exenatide, which inhibit GLP-1 breakdown and stimulate GLP-1 receptors, respectively, decreased nicotine intake in mice. Chemogenetic activation of GLP-1 neurons in NTS similarly decreased nicotine intake. Conversely, Glp1r knockout mice consumed greater quantities of nicotine than wild-type mice. Using optogenetic stimulation, we show that GLP-1 excites medial habenular (MHb) projections to the interpeduncular nucleus (IPN). Activation of GLP-1 receptors in the MHb-IPN circuit abolished nicotine reward and decreased nicotine intake, whereas their knockdown or pharmacological blockade increased intake. GLP-1 neurons may therefore serve as 'satiety sensors' for nicotine that stimulate habenular systems to promote nicotine avoidance before its aversive effects are encountered.

  3. Treatment Strategy for Type 2 Diabetes with Obesity: Focus on Glucagon-like Peptide-1 Receptor Agonists.

    PubMed

    Ji, Qiuhe

    2017-06-01

    The progressive nature of type 2 diabetes mellitus (T2DM) calls for step-wise intensification of therapy for maintaining normal glycemic levels and lowering cardiovascular (CV) risk. Because obesity is a prominent risk factor and comorbidity of T2DM, it further elevates the CV risk in T2DM. Therefore, it is vital to manage weight, obesity, and glycemic parameters for effective T2DM management. Few oral antidiabetic drugs (sulfonylureas and thiazolidinediones) and insulin are not suitable for obese patients with T2DM because these drugs cause weight gain. The present review discusses the place of glucagon-like peptide-1 receptor agonists (GLP-1RAs) in the treatment of obese patients with T2DM and the significance of these drugs in the prevention of future CV risk in patients with T2DM. A literature search of PubMed and EMBASE was conducted by using the search terms T2DM, GLP-1RAs, obesity, and cardiovascular complication. Randomized controlled trials measuring the effect of GLP-1RAs versus that of placebo on CV outcomes were included in the review. GLP-1RAs have emerged as a therapeutic alternative; these drugs exert their actions by providing glycemic control, improving insulin resistance and ö̇-cell function, and reducing weight. The risk of hypoglycemia with GLP-1RAs is minimal; however, GLP-1RAs are associated with gastrointestinal adverse events and raise concerns regarding pancreatitis. Combining GLP-1RAs with insulin analogues results in higher efficacy, a lowered insulin dose, and reduced insulin-related hypoglycemia and weight gain. Longer acting GLP-1RAs are also associated with improvement in medication adherence. Improvement in CV risk factors such as blood pressure and lipid profile further increases their usability for improving CV outcomes. Overall, the properties of GLP-1RAs make them suitable for combination with oral antidiabetic drugs in the early stages of T2DM and with insulins in the later stages for optimizing comprehensive management of the

  4. Hepatic functions of GLP-1 and its based drugs: current disputes and perspectives.

    PubMed

    Jin, Tianru; Weng, Jianping

    2016-09-01

    GLP-1 and its based drugs possess extrapancreatic metabolic functions, including that in the liver. These direct hepatic metabolic functions explain their therapeutic efficiency for subjects with insulin resistance. The direct hepatic functions could be mediated by previously assumed "degradation" products of GLP-1 without involving canonic GLP-1R. Although GLP-1 analogs were created as therapeutic incretins, extrapancreatic functions of these drugs, as well as native GLP-1, have been broadly recognized. Among them, the hepatic functions are particularly important. Postprandial GLP-1 release contributes to insulin secretion, which represses hepatic glucose production. This indirect effect of GLP-1 is known as the gut-pancreas-liver axis. Great efforts have been made to determine whether GLP-1 and its analogs possess direct metabolic effects on the liver, as the determination of the existence of direct hepatic effects may advance the therapeutic theory and clinical practice on subjects with insulin resistance. Furthermore, recent investigations on the metabolic beneficial effects of previously assumed "degradation" products of GLP-1 in the liver and elsewhere, including GLP-128-36 and GLP-132-36, have drawn intensive attention. Such investigations may further improve the development and the usage of GLP-1-based drugs. Here, we have reviewed the current advancement and the existing controversies on the exploration of direct hepatic functions of GLP-1 and presented our perspectives that the direct hepatic metabolic effects of GLP-1 could be a GLP-1 receptor-independent event involving Wnt signaling pathway activation. Copyright © 2016 the American Physiological Society.

  5. Btk inhibition suppresses agonist-induced human macrophage activation and inflammatory gene expression in RA synovial tissue explants.

    PubMed

    Hartkamp, Linda M; Fine, Jay S; van Es, Inge E; Tang, Man Wai; Smith, Michael; Woods, John; Narula, Satwant; DeMartino, Julie; Tak, Paul P; Reedquist, Kris A

    2015-08-01

    Bruton's tyrosine kinase (Btk) is required for B lymphocyte and myeloid cell contributions to pathology in murine models of arthritis. Here, we examined the potential contributions of synovial Btk expression and activation to inflammation in rheumatoid arthritis (RA). Btk was detected by immunohistochemistry and digital image analysis in synovial tissue from biologically naive RA (n=16) and psoriatic arthritis (PsA) (n=12) patients. Cell populations expressing Btk were identified by immunofluorescent double labelling confocal microscopy, quantitative (q-) PCR and immunoblotting. The effects of a Btk-specific inhibitor, RN486, on gene expression in human macrophages and RA synovial tissue explants (n=8) were assessed by qPCR, ELISA and single-plex assays. Btk was expressed at equivalent levels in RA and PsA synovial tissue, restricted to B lymphocytes, monocytes, macrophages and mast cells. RN486 significantly inhibited macrophage IL-6 production induced by Fc receptor and CD40 ligation. RN486 also reduced mRNA expression of overlapping gene sets induced by IgG, CD40 ligand (CD40L) and RA synovial fluid, and significantly suppressed macrophage production of CD40L-induced IL-8, TNF, MMP-1 and MMP-10, LPS-induced MMP-1, MMP-7 and MMP-10 production, and spontaneous production of IL-6, PDGF, CXCL-9 and MMP-1 by RA synovial explants. Btk is expressed equivalently in RA and PsA synovial tissue, primarily in macrophages. Btk activity is needed to drive macrophage activation in response to multiple agonists relevant to inflammatory arthritis, and promotes RA synovial tissue cytokine and MMP production. Pharmacological targeting of Btk may be of therapeutic benefit in the treatment of RA and other inflammatory diseases. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  6. The role of GLP-1 mimetics and basal insulin analogues in type 2 diabetes mellitus: guidance from studies of liraglutide

    PubMed Central

    Barnett, A H

    2012-01-01

    In people with type 2 diabetes mellitus (T2DM), the incretin effect is reduced, but the recent advent of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide (GLP)-1 agonists/analogues has enabled restoration of at least some of the function of the incretin system, with accompanying improvements in glycaemic control. Two GLP-1 receptor agonists/analogues are currently approved for the treatment of T2DM—exenatide (Byetta®, Eli Lilly & Co., Indianapolis, IN, US) and liraglutide (Victoza®, Novo Nordisk, Bagsvaerd, Denmark); a once-weekly formulation of exenatide (Bydureon®, Eli Lilly & Co.) has also been approved by the European Medicines Agency. The National Institute for Health and Clinical Excellence (NICE) has recently published guidance on the use of liraglutide in T2DM, based on evidence from the Liraglutide Effect and Action in Diabetes (LEAD) Phase III trial programme, which compared liraglutide with existing glucose-lowering therapies, such as exenatide and insulin glargine. The LEAD programme reported HbA1c reductions from 0.8 to 1.5% with liraglutide (1.2 and 1.8 mg), accompanied by low rates of hypoglycaemia and some weight loss; side effects were primarily gastrointestinal in nature (e.g. nausea and diarrhoea). Based on the findings of the LEAD studies and the NICE recommendation, liraglutide now represents an important therapy widely available in the UK for certain patient groups, including those with a body mass index (BMI) ≥35.0 kg/m2, and patients with a BMI <35 kg/m2 who are considered unsuitable for insulin and are failing to meet targets for glycaemic control with oral agents. NICE guidelines still suggest that most patients without considerable obesity (BMI <35 kg/m2) are probably best managed using insulin therapy. Evidence also suggests a future role for GLP-1 mimetics in combination with basal insulin. PMID:22051096

  7. Long-term Cost-effectiveness of Two GLP-1 Receptor Agonists for the Treatment of Type 2 Diabetes Mellitus in the Italian Setting: Liraglutide Versus Lixisenatide.

    PubMed

    Hunt, Barnaby; Kragh, Nana; McConnachie, Ceilidh C; Valentine, William J; Rossi, Maria C; Montagnoli, Roberta

    2017-07-01

    Maintaining glycemic control is the key treatment target for patients with type 2 diabetes mellitus. In addition, the glucagon-like peptide-1 (GLP-1) receptor agonists may be associated with other favorable treatment characteristics, such as reduction in body weight and reduced risk of hypoglycemia compared with traditional diabetes interventions. The aim of the present analysis was to compare the long-term cost-effectiveness of 2 GLP-1 receptor agonists, liraglutide 1.8 mg and lixisenatide 20 μg (both administered once daily), in the treatment of patients with type 2 diabetes failing to achieve glycemic control with metformin monotherapy in the Italian setting. The IMS CORE Diabetes Model was used to project long-term clinical outcomes and subsequent costs (in 2015 Euros [€]) associated with liraglutide 1.8 mg versus lixisenatide 20 μg treatment in a cohort with baseline characteristics derived from the open-label LIRA-LIXI trial (Efficacy and Safety of Liraglutide Versus Lixisenatide as Add-on to Metformin in Subjects With Type 2 Diabetes; NCT01973231) over patient lifetimes from the perspective of a health care payer. Efficacy data were taken from the 26-week end points of the same trial, including changes in glycated hemoglobin, body mass index, serum lipid levels, and hypoglycemic event rates. Outcomes projected included life expectancy, quality-adjusted life expectancy, cumulative incidence and time to onset of diabetes-related complications, and direct medical costs. Outcomes were discounted at 3% annually, and sensitivity analyses were performed. Liraglutide 1.8 mg was associated with improved discounted life expectancy (14.07 vs 13.96 years) and quality-adjusted life expectancy (9.18 vs 9.06 quality-adjusted life years [QALYs]) compared with lixisenatide 20 μg. These improvements were mostly attributable to a greater reduction in glycated hemoglobin level with liraglutide 1.8 mg versus lixisenatide 20 μg, leading to reduced incidence and

  8. Incretin-based therapy in type 2 diabetes: An evidence based systematic review and meta-analysis.

    PubMed

    Waldrop, Greer; Zhong, Jixin; Peters, Matthew; Goud, Aditya; Chen, Yin-Hsiu; Davis, Stephen N; Mukherjee, Bhramar; Rajagopalan, Sanjay

    2018-01-01

    Incretin based therapies such as dipeptidyl peptidase-4 inhibitors (DPP-4i) and glucagon-like peptide-1 receptor agonists (GLP-1Ra) are increasingly used for the treatment of Type 2 diabetes mellitus. In clinical practice and in previously performed clinical trials, these agents are often used in combination with other oral anti-diabetic agents (OADs) and Insulin. Prior meta-analytic reviews however do not adequately address the impact of background therapy and active comparator arms. Accordingly, we aimed to further investigate the efficacy of incretin based therapies by updating existing reviews by including clinical trial evidence after 2008; estimating the pooled effect of incretin therapies on glycemic efficacy and weight-loss, stratified by comparator therapy (placebo, mono-therapy, etc.), estimating the impact of background OADs and within class (GLP-1Ra or DPP-4i) comparative efficacy, on glycemia control. 82 randomized controlled trials after 2008 with glycemic control and weight loss as primary end-points were included. Both DPP-4i and GLP-1Ra reduced HbA1c, but only GLP-1Ra caused weight loss when compared to either active comparator drugs or placebo. GLP-1Ra were more effective than DPP-4i in glycemia lowering. Long acting GLP-1Ra were more effective in HbA1c lowering than short-acting agents but with similar weight loss effect. The effect of DPP-4i incretin glycemic efficacy was not modified by background therapy used in the study. Copyright © 2016. Published by Elsevier Inc.

  9. Oxyntomodulin differentially affects glucagon-like peptide-1 receptor beta-arrestin recruitment and signaling through Galpha(s).

    PubMed

    Jorgensen, Rasmus; Kubale, Valentina; Vrecl, Milka; Schwartz, Thue W; Elling, Christian E

    2007-07-01

    The glucagon-like peptide (GLP)-1 receptor is a promising target for the treatment of type 2 diabetes and obesity, and there is great interest in characterizing the pharmacology of the GLP-1 receptor and its ligands. In the present report, we have applied bioluminescence resonance energy transfer assays to measure agonist-induced recruitment of betaarrestins and G-protein-coupled receptor kinase (GRK) 2 to the GLP-1 receptor in addition to traditional measurements of second messenger generation. The peptide hormone oxyntomodulin is described in the literature as a full agonist on the glucagon and GLP-1 receptors. Surprisingly, despite being full agonists in GLP-1 receptor-mediated cAMP accumulation, oxyntomodulin and glucagon were observed to be partial agonists in recruiting betaarrestins and GRK2 to the GLP-1 receptor. We suggest that oxyntomodulin and glucagon are biased ligands on the GLP-1 receptor.

  10. Adjunctive Role of Glucagon-Like Peptide-1 Receptor Agonists in the Management of Type 1 Diabetes Mellitus.

    PubMed

    Harris, Kira B; Boland, Cassie L

    2016-09-01

    Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are commonly used in combination with insulin to manage type 2 diabetes mellitus, and four agents are currently approved for this indication: exenatide, liraglutide, dulaglutide, and albiglutide. The distinctive properties of GLP-1 RAs-potential hemoglobin A1c (A1C) reduction, weight loss, potential to reduce insulin doses, and lower hypoglycemia risk-have made these agents potential treatment options for patients with type 1 diabetes mellitus (T1DM) as well. These positive effects are due to glucose-dependent insulin secretion, reduced glucagon secretion, increased satiety, and delayed gastric emptying. Patients with T1DM are unable to suppress glucagon during meals, which contributes to postprandial hyperglycemia and may be improved with GLP-1 therapy. In this review, we evaluated the available literature on the clinical efficacy and safety of GLP-1 RAs in patients with T1DM. We conducted a search of the PubMed (1966-May 2016) and Ovid (1946-May 2016) databases. Abstracts presented at the scientific and clinical sessions of the American Diabetes Association and the American Association of Clinical Endocrinologists were also searched. The references of the published articles were also reviewed to identify additional studies appropriate for inclusion. All identified articles published in English were evaluated. Studies were included if they evaluated the clinical use or safety of GLP-1 RAs in patients with T1DM. Twelve studies were included, with four evaluating exenatide, one evaluating exenatide extended release, and seven evaluating liraglutide. Both exenatide and liraglutide showed significant reductions in hemoglobin A1C, plasma glucose concentration, body weight, and insulin doses when administered to patients with T1DM already receiving insulin therapy, without increasing the occurrence of hypoglycemia. Adverse effects were mostly gastrointestinal in nature but were mild and transient. Patients who may

  11. Exendin-4 Upregulates Adiponectin Level in Adipocytes via Sirt1/Foxo-1 Signaling Pathway

    PubMed Central

    Wang, Anping; Li, Ting; An, Ping; Yan, Wenhua; Zheng, Hua; Wang, Baoan; Mu, Yiming

    2017-01-01

    Glucagon-like peptide-1 (GLP-1) receptor plays an essential role in regulating glucose metabolism. GLP-1 receptor agonists have been widely used for treating diabetes and other insulin resistance-related diseases. However, mechanisms underlying the anti-diabetic effects of GLP-1 receptor agonists remain largely unknown. In this study, we investigated the effects of GLP-1 agonist exendin-4 on the expression of adiponectin, an insulin sensitizing hormone. We found that exendin-4 increased the expression and secretion of adiponectin both in vitro and in vivo. Our data showed that exendin-4 upregulated adiponectin expression at both mRNA and protein levels in adipocytes and adipose tissues. The effects of exendin-4 on adiponectin expression were dependent on the GLP-1 receptor. We further demonstrated important roles of Sirt1 and transcriptional factor Foxo-1 in mediating the function of exendin-4 in regulating adiponectin expression. Suppression of Sirt1 or Foxo-1 expression significantly impaired exendin-4-induced adiponectin expression. Consistently, exendin-4 up-regulated Sirt1 and Foxo-1 expression in vivo. Our work is the first study demonstrating the role of Sirt1/Foxo-1 in regulating the regulatory function of a GLP-1 receptor agonist in adiponectin expression both in vitro and in vivo. The results provide important information for the mechanism underlying the function of GLP-1R on improving insulin resistance and related diseases. PMID:28122026

  12. Hindbrain GLP-1 receptor mediation of cisplatin-induced anorexia and nausea.

    PubMed

    De Jonghe, Bart C; Holland, Ruby A; Olivos, Diana R; Rupprecht, Laura E; Kanoski, Scott E; Hayes, Matthew R

    2016-01-01

    While chemotherapy-induced nausea and vomiting are clinically controlled in the acute (<24 h) phase following treatment, the anorexia, nausea, fatigue, and other illness-type behaviors during the delayed phase (>24 h) of chemotherapy are largely uncontrolled. As the hindbrain glucagon-like peptide-1 (GLP-1) system contributes to energy balance and mediates aversive and stressful stimuli, here we examine the hypothesis that hindbrain GLP-1 signaling mediates aspects of chemotherapy-induced nausea and reductions in feeding behavior in rats. Specifically, hindbrain GLP-1 receptor (GLP-1R) blockade, via 4th intracerebroventricular (ICV) exendin-(9-39) injections, attenuates the anorexia, body weight reduction, and pica (nausea-induced ingestion of kaolin clay) elicited by cisplatin chemotherapy during the delayed phase (48 h) of chemotherapy-induced nausea. Additionally, the present data provide evidence that the central GLP-1-producing preproglucagon neurons in the nucleus tractus solitarius (NTS) of the caudal brainstem are activated by cisplatin during the delayed phase of chemotherapy-induced nausea, as cisplatin led to a significant increase in c-Fos immunoreactivity in NTS GLP-1-immunoreactive neurons. These data support a growing body of literature suggesting that the central GLP-1 system may be a potential pharmaceutical target for adjunct anti-emetics used to treat the delayed-phase of nausea and emesis, anorexia, and body weight loss that accompany chemotherapy treatments. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Naturally occurring glucagon-like peptide-2 (GLP-2) receptors in human intestinal cell lines.

    PubMed

    Sams, Anette; Hastrup, Sven; Andersen, Marie; Thim, Lars

    2006-02-17

    Although clinical trials with GLP-2 receptor agonists are currently ongoing, the mechanisms behind GLP-2-induced intestinal epithelial growth remain to be understood. To approach the GLP-2 mechanism of action this study aimed to identify intestinal cell lines endogenously expressing the GLP-2 receptor. Here we report the first identification of a cell line endogenously expressing functional GLP-2 receptors. The human intestinal epithelial cell line, FHC, expressed GLP-2 receptor encoding mRNA (RT-PCR) and GLP-2 receptor protein (Western blot). In cultured FHC cells, GLP-2 induced concentration dependent cAMP accumulation (pEC(50)=9.7+/-0.04 (mean+/-S.E.M., n=4)). In addition, a naturally occurring human intestinal fibroblast cell line, 18Co, endogenously expressing GLP-2 receptor encoding mRNA (RT-PCR) and protein (Western blot) was identified. No receptor functionality (binding or G-protein signalling) could be demonstrated in 18Co cells. The identified gut-relevant cell lines provide tools for future clarification of the mechanisms underlying GLP-2-induced epithelial growth.

  14. CORRELATION BETWEEN PRE AND POSTOPERATIVE LEVELS OF GLP-1/GLP-2 AND WEIGHT LOSS AFTER ROUX-EN-Y GASTRIC BYPASS: A PROSPECTIVE STUDY.

    PubMed

    Cazzo, Everton; Gestic, Martinho Antonio; Utrini, Murillo Pimentel; Pareja, José Carlos; Chaim, Elinton Adami; Geloneze, Bruno; Barreto, Maria Rita Lazzarini; Magro, Daniéla Oliveira

    2016-01-01

    The role of gut hormones in glucose homeostasis and weight loss achievement and maintenance after bariatric surgery appears to be a key point in the understanding of the beneficial effects observed following these procedures. To determine whether there is a correlation between the pre and postoperative levels of both GLP-1 and GLP-2 and the excess weight loss after Roux-en-Y gastric bypass (RYGB). An exploratory prospective study which enrolled 11 individuals who underwent RYGB and were followed-up for 12 months. GLP-1 and GLP-2 after standard meal tolerance test (MTT) were determined before and after surgery and then correlated with the percentage of excess loss (%EWL). GLP-2 AUC presented a significant postoperative increase (945.3±449.1 vs.1787.9±602.7; p=0.0037); GLP-1 AUC presented a non-significant trend towards increase after RYGB (709.6±320.4 vs. 1026.5±714.3; p=0.3808). Mean %EWL was 66.7±12.2%. There was not any significant correlation between both the pre and postoperative GLP-1 AUCs and GLP-2 AUCs and the %EWL achieved after one year. There was no significant correlation between the pre and postoperative levels of the areas under the GLP-1 and GLP-2 curves with the percentage of weight loss reached after one year. O papel de hormônios gastrointestinais sobre a homeostase glicêmica e a obtenção e manutenção da perda de peso após a cirurgia bariátrica parece ser elemento fundamental na compreensão dos benefícios observados após estes procedimentos. Determinar se há correlação entre os níveis pré e pós-operatórios de GLP-1 e GLP-2 com a perda do excesso de peso após o bypass gástrico em Y-de-Roux. Estudo prospectivo exploratório que envolveu 11 indivíduos submetidos ao bypass gástrico, acompanhados por 12 meses. Os níveis GLP-1 e GLP-2 após um teste de refeição padrão foram determinados antes e 12 meses após a operação e então foram correlacionados com o percentual de perda do excesso de peso. Houve aumento

  15. Endogenous GLP-1 in lateral septum contributes to stress-induced hypophagia.

    PubMed

    Terrill, Sarah J; Maske, Calyn B; Williams, Diana L

    2018-03-03

    Glucagon-like peptide 1 (GLP-1) neurons of the caudal brainstem project to many brain areas, including the lateral septum (LS), which has a known role in stress responses. Previously, we showed that endogenous GLP-1 in the LS plays a physiologic role in the control of feeding under non-stressed conditions, however, central GLP-1 is also involved in behavioral and endocrine responses to stress. Here, we asked whether LS GLP-1 receptors (GLP-1R) contribute to stress-induced hypophagia. Male rats were implanted with bilateral cannulas targeting the dorsal subregion of the LS (dLS). In a within-subjects design, shortly before the onset of the dark phase, rats received dLS injections of saline or the GLP-1R antagonist Exendin (9-39) (Ex9) prior to 30 min restraint stress. Food intake was measured continuously for the next 20 h. The stress-induced hypophagia observed within the first 30 min of dark was not influenced by Ex9 pretreatment, but Ex9 tended to blunt the effect of stress as early as 1 and 2 h into the dark phase. By 4-6 h, there were significant stress X drug interactions, and Ex9 pretreatment blocked the stress-induced suppression of feeding. These effects were mediated entirely through changes in average meal size; stress suppressed meal size while dLS Ex9 attenuated this effect. Using a similar design, we examined the role of dLS GLP-1R in the neuroendocrine response to acute restraint stress. As expected, stress potently increased serum corticosterone, but blockade of dLS GLP-1Rs did not affect this response. Together, these data show that endogenous GLP-1 action in the dLS plays a role in some but not all of the physiologic responses to acute stress. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Modulation of taste sensitivity by GLP-1 signaling in taste buds.

    PubMed

    Martin, Bronwen; Dotson, Cedrick D; Shin, Yu-Kyong; Ji, Sunggoan; Drucker, Daniel J; Maudsley, Stuart; Munger, Steven D

    2009-07-01

    Modulation of sensory function can help animals adjust to a changing external and internal environment. Even so, mechanisms for modulating taste sensitivity are poorly understood. Using immunohistochemical, biochemical, and behavioral approaches, we found that the peptide hormone glucagon-like peptide-1 (GLP-1) and its receptor (GLP-1R) are expressed in mammalian taste buds. Furthermore, we found that GLP-1 signaling plays an important role in the modulation of taste sensitivity: GLP-1R knockout mice exhibit a dramatic reduction in sweet taste sensitivity as well as an enhanced sensitivity to umami-tasting stimuli. Together, these findings suggest a novel paracrine mechanism for the hormonal modulation of taste function in mammals.

  17. Low incidence of anti-drug antibodies in patients with type 2 diabetes treated with once-weekly glucagon-like peptide-1 receptor agonist dulaglutide.

    PubMed

    Milicevic, Z; Anglin, G; Harper, K; Konrad, R J; Skrivanek, Z; Glaesner, W; Karanikas, C A; Mace, K

    2016-05-01

    Therapeutic administration of peptides may result in anti-drug antibody (ADA) formation, hypersensitivity adverse events (AEs) and reduced efficacy. As a large peptide, the immunogenicity of once-weekly glucagon-like peptide-1 (GLP-1) receptor agonist dulaglutide is of considerable interest. The present study assessed the incidence of treatment-emergent dulaglutide ADAs, hypersensitivity AEs, injection site reactions (ISRs), and glycaemic control in ADA-positive patients in nine phase II and phase III trials (dulaglutide, N = 4006; exenatide, N = 276; non-GLP-1 comparators, N = 1141). Treatment-emergent dulaglutide ADAs were detected using a solid-phase extraction acid dissociation binding assay. Neutralizing ADAs were detected using a cell-based assay derived from human endothelial kidney cells (HEK293). A total of 64 dulaglutide-treated patients (1.6% of the population) tested ADA-positive versus eight (0.7%) from the non-GLP-1 comparator group. Of these 64 patients, 34 (0.9%) had dulaglutide-neutralizing ADAs, 36 (0.9%) had native-sequence GLP-1 (nsGLP-1) cross-reactive ADAs and four (0.1%) had nsGLP-1 neutralization ADAs. The incidence of hypersensitivity AEs and ISRs was similar in the dulaglutide versus placebo groups. No dulaglutide ADA-positive patient reported hypersensitivity AEs. Because of the low incidence of ADAs, it was not possible to establish their effect on glycaemic control. © 2016 John Wiley & Sons Ltd.

  18. The CTRB1/2 Locus Affects Diabetes Susceptibility and Treatment via the Incretin Pathway

    PubMed Central

    ‘t Hart, Leen M.; Fritsche, Andreas; Nijpels, Giel; van Leeuwen, Nienke; Donnelly, Louise A.; Dekker, Jacqueline M.; Alssema, Marjan; Fadista, Joao; Carlotti, Françoise; Gjesing, Anette P.; Palmer, Colin N.A.; van Haeften, Timon W.; Herzberg-Schäfer, Silke A.; Simonis-Bik, Annemarie M.C.; Houwing-Duistermaat, Jeanine J.; Helmer, Quinta; Deelen, Joris; Guigas, Bruno; Hansen, Torben; Machicao, Fausto; Willemsen, Gonneke; Heine, Robert J.; Kramer, Mark H.H.; Holst, Jens J.; de Koning, Eelco J.P.; Häring, Hans-Ulrich; Pedersen, Oluf; Groop, Leif; de Geus, Eco J.C.; Slagboom, P. Eline; Boomsma, Dorret I.; Eekhoff, Elisabeth M.W.; Pearson, Ewan R.; Diamant, Michaela

    2013-01-01

    The incretin hormone glucagon-like peptide 1 (GLP-1) promotes glucose homeostasis and enhances β-cell function. GLP-1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors, which inhibit the physiological inactivation of endogenous GLP-1, are used for the treatment of type 2 diabetes. Using the Metabochip, we identified three novel genetic loci with large effects (30–40%) on GLP-1–stimulated insulin secretion during hyperglycemic clamps in nondiabetic Caucasian individuals (TMEM114; CHST3 and CTRB1/2; n = 232; all P ≤ 8.8 × 10−7). rs7202877 near CTRB1/2, a known diabetes risk locus, also associated with an absolute 0.51 ± 0.16% (5.6 ± 1.7 mmol/mol) lower A1C response to DPP-4 inhibitor treatment in G-allele carriers, but there was no effect on GLP-1 RA treatment in type 2 diabetic patients (n = 527). Furthermore, in pancreatic tissue, we show that rs7202877 acts as expression quantitative trait locus for CTRB1 and CTRB2, encoding chymotrypsinogen, and increases fecal chymotrypsin activity in healthy carriers. Chymotrypsin is one of the most abundant digestive enzymes in the gut where it cleaves food proteins into smaller peptide fragments. Our data identify chymotrypsin in the regulation of the incretin pathway, development of diabetes, and response to DPP-4 inhibitor treatment. PMID:23674605

  19. Carboxy-terminal truncation activates glp-1 protein to specify vulval fates in Caenorhabditis elegans.

    PubMed

    Mango, S E; Maine, E M; Kimble, J

    1991-08-29

    The glp-1 and lin-12 genes encode homologous transmembrane proteins that may act as receptors for cell interactions during development. The glp-1 product is required for induction of germ-line proliferation and for embryogenesis. By contrast, lin-12 mediates somatic cell interactions, including those between the precursor cells that form the vulval hypodermis (VPCs). Here we analyse an unusual allele of glp-1, glp-1(q35), which displays a semidominant multivulva phenotype (Muv), as well as the typical recessive, loss-of-function Glp phenotypes (sterility and embryonic lethality). We find that the effects of glp-1(q35) on VPC development mimic those of dominant lin-12 mutations, even in the absence of lin-12 activity. The glp-1(q35) gene bears a nonsense mutation predicted to eliminate the 122 C-terminal amino acids, including a ProGluSerThr (PEST) sequence thought to destabilize proteins. We suggest that the carboxy terminus bears a negative regulatory domain which normally inactivates glp-1 in the VPCs. We propose that inappropriate glp-1(q35) activity can substitute for lin-12 to determine vulval fate, perhaps by driving the VPCs to proliferate.

  20. Crystal structure of glucagon-like peptide-1 in complex with the extracellular domain of the glucagon-like peptide-1 receptor.

    PubMed

    Underwood, Christina Rye; Garibay, Patrick; Knudsen, Lotte Bjerre; Hastrup, Sven; Peters, Günther H; Rudolph, Rainer; Reedtz-Runge, Steffen

    2010-01-01

    GLP-1 (glucagon-like peptide-1) is an incretin released from intestinal L-cells in response to food intake. Activation of the GLP-1 receptor potentiates the synthesis and release of insulin from pancreatic beta-cells in a glucose-dependent manner. The GLP-1 receptor belongs to class B of the G-protein-coupled receptors, a subfamily characterized by a large N-terminal extracellular ligand binding domain. Exendin-4 and GLP-1 are 50% identical, and exendin-4 is a full agonist with similar affinity and potency for the GLP-1 receptor. We recently solved the crystal structure of the GLP-1 receptor extracellular domain in complex with the competitive antagonist exendin-4(9-39). Interestingly, the isolated extracellular domain binds exendin-4 with much higher affinity than the endogenous agonist GLP-1. Here, we have solved the crystal structure of the extracellular domain in complex with GLP-1 to 2.1 Aresolution. The structure shows that important hydrophobic ligand-receptor interactions are conserved in agonist- and antagonist-bound forms of the extracellular domain, but certain residues in the ligand-binding site adopt a GLP-1-specific conformation. GLP-1 is a kinked but continuous alpha-helix from Thr(13) to Val(33) when bound to the extracellular domain. We supplemented the crystal structure with site-directed mutagenesis to link the structural information of the isolated extracellular domain with the binding properties of the full-length receptor. The data support the existence of differences in the binding modes of GLP-1 and exendin-4 on the full-length GLP-1 receptor.

  1. Duodenal GLP-1 signaling regulates hepatic glucose production through a PKC-δ-dependent neurocircuitry

    PubMed Central

    Yang, Mengliu; Wang, Jinzhi; Wu, Shaobo; Yuan, Lei; Zhao, Xiaodong; Liu, Chaohong; Xie, Jing; Jia, Yanjun; Lai, Yerui; Zhao, Allan Zijian; Boden, Guenther; Li, Ling; Yang, Gangyi

    2017-01-01

    Intestinal glucagon-like peptide-1 (GLP-1) is a hormone that stimulates insulin secretion and acts as a neuropeptide to control glucose homeostasis, but little is known whether intestinal GLP-1 has any effect in the control of hepatic glucose production (HGP). Here we found that intraduodenal infusion of GLP-1 activated duodenal PKC-δ, lowered HGP and was accompanied by a decrease in hepatic expression of gluconeogenic enzymes and an increase in hepatic insulin signaling in rats. However, gut co-infusion of either the GLP-1 receptor antagonist Ex-9, or the PKC-δ inhibitor rottlerin with GLP-1, negated the ability of gut GLP-1 to lower HGP and to increase hepatic insulin signaling during clamps. The metabolic and molecular signal effects of duodenal GLP-1 were also negated by co-infusion with tetracaine, pharmacologic inhibition of N-methyl-d-aspartate receptors within the dorsalvagal complex, or hepatic vagotomy in rats. In summary, we identified a neural glucoregulatory function of gut GLP-1 signaling. PMID:28182013

  2. Evaluation of novel TGR5 agonist in combination with Sitagliptin for possible treatment of type 2 diabetes.

    PubMed

    Agarwal, Sameer; Sasane, Santosh; Kumar, Jeevan; Deshmukh, Prashant; Bhayani, Hitesh; Giri, Poonam; Giri, Suresh; Soman, Shubhangi; Kulkarni, Neelima; Jain, Mukul

    2018-06-01

    TGR5 is a member of G protein-coupled receptor (GPCR) superfamily, a promising molecular target for metabolic diseases. Activation of TGR5 promotes secretion of glucagon-like peptide-1 (GLP-1), which activates insulin secretion. A series of 2-thio-imidazole derivatives have been identified as novel, potent and orally efficacious TGR5 agonists. Compound 4d, a novel TGR5 agonist, in combination with Sitagliptin, a DPP-4 inhibitor, has demonstrated an adequate GLP-1 secretion and glucose lowering effect in animal models, suggesting a potential clinical option in treatment of type-2 diabetes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. IL-6-Type Cytokine Signaling in Adipocytes Induces Intestinal GLP-1 Secretion.

    PubMed

    Wueest, Stephan; Laesser, Céline I; Böni-Schnetzler, Marianne; Item, Flurin; Lucchini, Fabrizio C; Borsigova, Marcela; Müller, Werner; Donath, Marc Y; Konrad, Daniel

    2018-01-01

    We recently showed that interleukin (IL)-6-type cytokine signaling in adipocytes induces free fatty acid release from visceral adipocytes, thereby promoting obesity-induced hepatic insulin resistance and steatosis. In addition, IL-6-type cytokines may increase the release of leptin from adipocytes and by those means induce glucagon-like peptide 1 (GLP-1) secretion. We thus hypothesized that IL-6-type cytokine signaling in adipocytes may regulate insulin secretion. To this end, mice with adipocyte-specific knockout of gp130, the signal transducer protein of IL-6, were fed a high-fat diet for 12 weeks. Compared with control littermates, knockout mice showed impaired glucose tolerance and circulating leptin, GLP-1, and insulin levels were reduced. In line, leptin release from isolated adipocytes was reduced, and intestinal proprotein convertase subtilisin/kexin type 1 ( Pcsk1 ) expression, the gene encoding PC1/3, which controls GLP-1 production, was decreased in knockout mice. Importantly, treatment with the GLP-1 receptor antagonist exendin 9-39 abolished the observed difference in glucose tolerance between control and knockout mice. Ex vivo, supernatant collected from isolated adipocytes of gp130 knockout mice blunted Pcsk1 expression and GLP-1 release from GLUTag cells. In contrast, glucose- and GLP-1-stimulated insulin secretion was not affected in islets of knockout mice. In conclusion, adipocyte-specific IL-6 signaling induces intestinal GLP-1 release to enhance insulin secretion, thereby counteracting insulin resistance in obesity. © 2017 by the American Diabetes Association.

  4. Critical role for GLP-1 in symptomatic post-bariatric hypoglycaemia.

    PubMed

    Craig, Colleen M; Liu, Li-Fen; Deacon, Carolyn F; Holst, Jens J; McLaughlin, Tracey L

    2017-03-01

    Post-bariatric hypoglycaemia (PBH) is a rare, but severe, metabolic disorder arising months to years after bariatric surgery. It is characterised by symptomatic postprandial hypoglycaemia, with inappropriately elevated insulin concentrations. The relative contribution of exaggerated incretin hormone signalling to dysregulated insulin secretion and symptomatic hypoglycaemia is a subject of ongoing inquiry. This study was designed to test the hypothesis that PBH and associated symptoms are primarily mediated by glucagon-like peptide-1 (GLP-1). We conducted a double-blinded crossover study wherein eight participants with confirmed PBH were assigned in random order to intravenous infusion of the GLP-1 receptor (GLP-1r) antagonist. Exendin (9-39) (Ex-9), or placebo during an OGTT on two separate days at the Stanford University Clinical and Translational Research Unit. Metabolic, symptomatic and pharmacokinetic variables were evaluated. Results were compared with a cohort of BMI- and glucose-matched non-surgical controls (NSCs). Infusion of Ex-9 decreased the time to peak glucose and rate of glucose decline during OGTT, and raised the postprandial nadir by over 70%, normalising it relative to NSCs and preventing hypoglycaemia in all PBH participants. Insulin AUC and secretion rate decreased by 57% and 71% respectively, and peak postprandial insulin was normalised relative to NSCs. Autonomic and neuroglycopenic symptoms were significantly reduced during Ex-9 infusion. GLP-1r blockade prevented hypoglycaemia in 100% of individuals, normalised beta cell function and reversed neuroglycopenic symptoms, supporting the conclusion that GLP-1 plays a primary role in mediating hyperinsulinaemic hypoglycaemia in PBH. Competitive antagonism at the GLP-1r merits consideration as a therapeutic strategy. ClinicalTrials.gov NCT02550145.

  5. The role of GLP-1 mimetics and basal insulin analogues in type 2 diabetes mellitus: guidance from studies of liraglutide.

    PubMed

    Barnett, A H

    2012-04-01

    In people with type 2 diabetes mellitus (T2DM), the incretin effect is reduced, but the recent advent of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide (GLP)-1 agonists/analogues has enabled restoration of at least some of the function of the incretin system, with accompanying improvements in glycaemic control. Two GLP-1 receptor agonists/analogues are currently approved for the treatment of T2DM-exenatide (Byetta®, Eli Lilly & Co., Indianapolis, IN, US) and liraglutide (Victoza®, Novo Nordisk, Bagsvaerd, Denmark); a once-weekly formulation of exenatide (Bydureon®, Eli Lilly & Co.) has also been approved by the European Medicines Agency. The National Institute for Health and Clinical Excellence (NICE) has recently published guidance on the use of liraglutide in T2DM, based on evidence from the Liraglutide Effect and Action in Diabetes (LEAD) Phase III trial programme, which compared liraglutide with existing glucose-lowering therapies, such as exenatide and insulin glargine. The LEAD programme reported HbA1c reductions from 0.8 to 1.5% with liraglutide (1.2 and 1.8 mg), accompanied by low rates of hypoglycaemia and some weight loss; side effects were primarily gastrointestinal in nature (e.g. nausea and diarrhoea). Based on the findings of the LEAD studies and the NICE recommendation, liraglutide now represents an important therapy widely available in the UK for certain patient groups, including those with a body mass index (BMI) ≥35.0 kg/m(2) , and patients with a BMI <35 kg/m(2) who are considered unsuitable for insulin and are failing to meet targets for glycaemic control with oral agents. NICE guidelines still suggest that most patients without considerable obesity (BMI <35 kg/m(2) ) are probably best managed using insulin therapy. Evidence also suggests a future role for GLP-1 mimetics in combination with basal insulin. © 2011 Blackwell Publishing Ltd.

  6. Synthesis of potent agonists of substance P by replacement of Met11 with Glu(OBzl) and N-terminal glutamine with Glp of the C-terminal hexapeptide and heptapeptide of substance P.

    PubMed

    Stavropoulos, G; Karagiannis, K; Anagnostides, S; Ministrouski, I; Selinger, Z; Chorev, M

    1995-06-01

    The analogues [Glp6,Glu(OBzl)11]SP(6-11) and [Glp5,Glu(OBzl)11]SP(5-11) of the C-terminal hexapeptide and heptapeptide of Substance P have been synthesized by conventional solution methods. In each analogue the N-terminal glutamine has been replaced by pyroglutamic acid, while the COOCH2C6H5 ester group has replaced the SCH3 group of the Met11 side chain. The in vitro activity of both analogues has been determined on three biological preparations: guinea pig ileum (GPI), rat vas deferens (RVD) and rat portal vein (RPV). The results showed that both analogues are highly potent and selective agonists on GPI through the NK-1 receptor. They are more potent than SP itself, with 1.54 and 1.25 respective values of relative potency on GPI. Their selectivity has been studied by utilizing atropine-treated guinea pig ileum (GPI+At). The analogues showed low activity on RVD and RPV tissues, which represent NK-2 and NK-3 monoreceptor assay, respectively.

  7. Sepsis-induced activation of endogenous GLP-1 system is enhanced in type 2 diabetes.

    PubMed

    Perl, Sivan H; Bloch, Olga; Zelnic-Yuval, Dana; Love, Itamar; Mendel-Cohen, Lior; Flor, Hadar; Rapoport, Micha J

    2018-05-01

    High levels of circulating GLP-1 are associated with severity of sepsis in critically ill nondiabetic patients. Whether patients with type 2 diabetes (T2D) display different activation of the endogenous GLP-1 system during sepsis and whether it is affected by diabetes-related metabolic parameters are not known. Serum levels of GLP-1 (total and active forms) and its inhibitor enzyme sDPP-4 were determined by ELISA on admission and after 2 to 4 days in 37 sepsis patients with (n = 13) and without T2D (n = 24) and compared to normal healthy controls (n = 25). Correlations between GLP-1 system activation and clinical, inflammatory, and diabetes-related metabolic parameters were performed. A 5-fold (P < .001) and 2-fold (P < .05) increase in active and total GLP-1 levels, respectively, were found on admission as compared to controls. At 2 to 4 days from admission, the level of active GLP-1 forms in surviving patients were decreased significantly (P < .005), and positively correlated with inflammatory marker CRP (r = 0.33, P = .05). T2D survivors displayed a similar but more enhanced pattern of GLP-1 response than nondiabetic survivors. Nonsurvivors demonstrate an early extreme increase of both total and active GLP-1 forms, 9.5-fold and 5-fold, respectively (P < .05). The initial and late levels of circulating GLP-1 inhibitory enzyme sDPP-4 were twice lower in all studied groups (P < .001), compared with healthy controls. Taken together, these data indicate that endogenous GLP-1 system is activated during sepsis. Patients with T2D display an enhanced and prolonged activation as compared to nondiabetic patients. Extreme early increased GLP-1 levels during sepsis indicate poor prognosis. Copyright © 2018 John Wiley & Sons, Ltd.

  8. Crystal Structure of Glucagon-like Peptide-1 in Complex with the Extracellular Domain of the Glucagon-like Peptide-1 Receptor*

    PubMed Central

    Underwood, Christina Rye; Garibay, Patrick; Knudsen, Lotte Bjerre; Hastrup, Sven; Peters, Günther H.; Rudolph, Rainer; Reedtz-Runge, Steffen

    2010-01-01

    GLP-1 (glucagon-like peptide-1) is an incretin released from intestinal L-cells in response to food intake. Activation of the GLP-1 receptor potentiates the synthesis and release of insulin from pancreatic β-cells in a glucose-dependent manner. The GLP-1 receptor belongs to class B of the G-protein-coupled receptors, a subfamily characterized by a large N-terminal extracellular ligand binding domain. Exendin-4 and GLP-1 are 50% identical, and exendin-4 is a full agonist with similar affinity and potency for the GLP-1 receptor. We recently solved the crystal structure of the GLP-1 receptor extracellular domain in complex with the competitive antagonist exendin-4(9–39). Interestingly, the isolated extracellular domain binds exendin-4 with much higher affinity than the endogenous agonist GLP-1. Here, we have solved the crystal structure of the extracellular domain in complex with GLP-1 to 2.1 Åresolution. The structure shows that important hydrophobic ligand-receptor interactions are conserved in agonist- and antagonist-bound forms of the extracellular domain, but certain residues in the ligand-binding site adopt a GLP-1-specific conformation. GLP-1 is a kinked but continuous α-helix from Thr13 to Val33 when bound to the extracellular domain. We supplemented the crystal structure with site-directed mutagenesis to link the structural information of the isolated extracellular domain with the binding properties of the full-length receptor. The data support the existence of differences in the binding modes of GLP-1 and exendin-4 on the full-length GLP-1 receptor. PMID:19861722

  9. Blockade of Central GLP-1 Receptors Deteriorates the Improvement of Diabetes after Ileal Transposition.

    PubMed

    Chen, Weijie; Xu, Qianqian; Xiao, Yiding; Zhou, Jiaolin; Zhang, Weimin; Lin, Guole; Gong, Fengying

    2016-01-01

    Background: The mechanism of improvement of type 2 diabetes mellitus induced by ileal transposition (IT) is undefined. Our aim was to investigate the possible role of central glucagon-like peptide 1 (GLP-1) after IT. Methods: Ninety male diabetic rats were randomly divided into the IT, sham IT (S-IT) and control group. The food intake, glucose metabolism and GLP-1 level were measured. Subsequently, we administered GLP-1 antagonist via lateral brain ventricle cannula to block central GLP-1 receptor, and verified whether the food intake, glucose metabolism changed. And the activated pro-opiomelanocortin (POMC) neurons in different groups were compared after sacrifice. Results: IT induced significant diabetic improvement with decreased maximum food intake and higher postprandial GLP-1 level. The GLP-1 level in cerebrospinal fluid increased in correlation with the plasma GLP-1 level. When the central GLP-1 receptor antagonist was given to the IT group rats, the improvement of the glucose level declined. The glucose level surged (169.9 ± 14.2) % during the oral glucose tolerance test, the range was larger than that before central blockade ((67.1 ± 14.2) %, P < 0.001). Moreover, the POMC neuron number in the arcuate nucleus of the hypothalamus were reduced (12.7 ± 6.1 at a magnification of 100×). The relative content level of POMC-derived peptides in the pituitary was lower (0.1 ± 0.05). Conclusions: The central GLP-1 might play an important role in the remission of diabetes after IT. POMC neurons in the hypothalamus may be activated by the enhanced level of GLP-1 after IT.

  10. Sustained expression of GLP-1 receptor differentially modulates β-cell functions in diabetic and nondiabetic mice

    PubMed Central

    Kubo, Fumiyo; Miyatsuka, Takeshi; Sasaki, Shugo; Takahara, Mitsuyoshi; Yamamoto, Yuichi; Shimo, Naoki; Watada, Hirotaka; Kaneto, Hideaki; Gannon, Maureen; Matsuoka, Taka-aki; Shimomura, Iichiro

    2017-01-01

    Glucagon-like peptide 1 (GLP-1) has been shown to play important roles in maintaining β-cell functions, such as insulin secretion and proliferation. While expression levels of GLP-1 receptor (Glp1r) are compromised in the islets of diabetic rodents, it remains unclear when and to what degree Glp1r mRNA levels are decreased during the progression of diabetes. In this study, we performed real-time PCR with the islets of db/db diabetic mice at different ages, and found that the expression levels of Glp1r were comparable to those of the islets of nondiabetic db/misty controls at the age of four weeks, and were significantly decreased at the age of eight and 12 weeks. To investigate whether restored expression of Glp1r affects the diabetic phenotypes, we generated the transgenic mouse model Pdx1PB-CreER™; CAG-CAT-Glp1r (βGlp1r) that allows for induction of Glp1r expression specifically in β cells. Whereas the expression of exogenous Glp1r had no measurable effect on glucose tolerance in nondiabetic βGlp1r;db/misty mice, βGlp1r;db/db mice exhibited higher glucose and lower insulin levels in blood on glucose challenge test than control db/db littermates. In contrast, four weeks of treatment with exendin-4 improved the glucose profiles and increased serum insulin levels in βGlp1r;db/db mice, to significantly higher levels than those in control db/db mice. These differential effects of exogenous Glp1r in nondiabetic and diabetic mice suggest that downregulation of Glp1r might be required to slow the progression of β-cell failure under diabetic conditions. PMID:26854076

  11. Extending residence time and stability of peptides by Protected Graft Copolymer (PGC) excipient: GLP-1 example

    PubMed Central

    Castillo, Gerardo M.; Reichstetter, Sandra; Bolotin, Elijah M.

    2011-01-01

    Purpose The purpose of this study is to determine whether a Protected Graft Copolymer (PGC) containing fatty acid can be used as a stabilizing excipient for GLP-1 and whether PGC/GLP-1 given once a week can be an effective treatment for diabetes. Methods To create a PGC excipient, polylysine was grafted with methoxypolyethyleneglycol and fatty acid at the epsilon amino groups. We performed evaluation of 1) the binding of excipient to GLP-1, 2) the DPP IV sensitivity of GLP-1 formulated with PGC as the excipient, 3) the in vitro bio-activity of excipient-formulated GLP-1, 4) the in vivo pharmacokinetics of excipient-formulated GLP-1, and 5) the efficacy of the excipient-formulated GLP-1 in diabetic rats. Results We showed reproducible synthesis of PGC excipient, showed high affinity binding of PGC to GLP-1, slowed protease degradation of excipient-formulated GLP-1, and showed that excipient-formulated GLP-1 induced calcium influx in INS cells. Excipient-formulated GLP-1 stays in the blood for at least 4 days. When excipient-formulated GLP-1 was given subcutaneously once a week to diabetic ZDF rats, a significant reduction of HbA1c compared to control was observed. The reduction is similar to diabetic ZDF rats given exendin twice a day. Conclusions PGC can be an ideal in vivo stabilizing excipient for biologically labile peptides. PMID:21830140

  12. Sustained expression of GLP-1 receptor differentially modulates β-cell functions in diabetic and nondiabetic mice

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kubo, Fumiyo; Miyatsuka, Takeshi, E-mail: miyatsuka-takeshi@umin.net; Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421

    2016-02-26

    Glucagon-like peptide 1 (GLP-1) has been shown to play important roles in maintaining β-cell functions, such as insulin secretion and proliferation. While expression levels of GLP-1 receptor (Glp1r) are compromised in the islets of diabetic rodents, it remains unclear when and to what degree Glp1r mRNA levels are decreased during the progression of diabetes. In this study, we performed real-time PCR with the islets of db/db diabetic mice at different ages, and found that the expression levels of Glp1r were comparable to those of the islets of nondiabetic db/misty controls at the age of four weeks, and were significantly decreasedmore » at the age of eight and 12 weeks. To investigate whether restored expression of Glp1r affects the diabetic phenotypes, we generated the transgenic mouse model Pdx1{sup PB}-CreER{sup TM}; CAG-CAT-Glp1r (βGlp1r) that allows for induction of Glp1r expression specifically in β cells. Whereas the expression of exogenous Glp1r had no measurable effect on glucose tolerance in nondiabetic βGlp1r;db/misty mice, βGlp1r;db/db mice exhibited higher glucose and lower insulin levels in blood on glucose challenge test than control db/db littermates. In contrast, four weeks of treatment with exendin-4 improved the glucose profiles and increased serum insulin levels in βGlp1r;db/db mice, to significantly higher levels than those in control db/db mice. These differential effects of exogenous Glp1r in nondiabetic and diabetic mice suggest that downregulation of Glp1r might be required to slow the progression of β-cell failure under diabetic conditions. - Highlights: • Expression levels of incretin receptors were significantly decreased in diabetic db/db islets after the age of eight weeks. • A transgenic mouse model expressing Glp1r specifically in β cells was generated. • Exogenous expression of Glp1r in β cells did not affect metabolic profiles in nondiabetic mice. • Sustained expression of Glp1r in diabetic db/db β cells

  13. Fructose stimulates GLP-1 but not GIP secretion in mice, rats, and humans

    PubMed Central

    Kuhre, Rune E.; Gribble, Fiona M.; Hartmann, Bolette; Reimann, Frank; Windeløv, Johanne A.; Rehfeld, Jens F.

    2014-01-01

    Nutrients often stimulate gut hormone secretion, but the effects of fructose are incompletely understood. We studied the effects of fructose on a number of gut hormones with particular focus on glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). In healthy humans, fructose intake caused a rise in blood glucose and plasma insulin and GLP-1, albeit to a lower degree than isocaloric glucose. Cholecystokinin secretion was stimulated similarly by both carbohydrates, but neither peptide YY3–36 nor glucagon secretion was affected by either treatment. Remarkably, while glucose potently stimulated GIP release, fructose was without effect. Similar patterns were found in the mouse and rat, with both fructose and glucose stimulating GLP-1 secretion, whereas only glucose caused GIP secretion. In GLUTag cells, a murine cell line used as model for L cells, fructose was metabolized and stimulated GLP-1 secretion dose-dependently (EC50 = 0.155 mM) by ATP-sensitive potassium channel closure and cell depolarization. Because fructose elicits GLP-1 secretion without simultaneous release of glucagonotropic GIP, the pathways underlying fructose-stimulated GLP-1 release might be useful targets for type 2 diabetes mellitus and obesity drug development. PMID:24525020

  14. Ghrelin suppresses cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) in the intestine, and attenuates the anorectic effects of CCK, PYY and GLP-1 in goldfish (Carassius auratus).

    PubMed

    Blanco, Ayelén Melisa; Bertucci, Juan Ignacio; Valenciano, Ana Isabel; Delgado, María Jesús; Unniappan, Suraj

    2017-07-01

    Ghrelin is an important gut-derived hormone with an appetite stimulatory role, while most of the intestinal hormones, including cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 (GLP-1), are appetite-inhibitors. Whether these important peptides with opposing roles on food intake interact to regulate energy balance in fish is currently unknown. The aim of this study was to characterize the putative crosstalk between ghrelin and CCK, PYY and GLP-1 in goldfish (Carassius auratus). We first determined the localization of CCK, PYY and GLP-1 in relation to ghrelin and its main receptor GHS-R1a (growth hormone secretagogue 1a) in the goldfish intestine by immunohistochemistry. Colocalization of ghrelin/GHS-R1a and CCK/PYY/GLP-1 was found primarily in the luminal border of the intestinal mucosa. In an intestinal explant culture, a significant decrease in prepro-cck, prepro-pyy and proglucagon transcript levels was observed after 60min of incubation with ghrelin, which was abolished by preincubation with the GHS-R1a ghrelin receptor antagonist [D-Lys3]-GHRP-6 (except for proglucagon). The protein expression of PYY and GLP-1 was also downregulated by ghrelin. Finally, intraperitoneal co-administration of CCK, PYY or GLP-1 with ghrelin results in no modification of food intake in goldfish. Overall, results of the present study show for the first time in fish that ghrelin exerts repressive effects on enteric anorexigens. It is likely that these interactions mediate the stimulatory effects of ghrelin on feeding and metabolism in fish. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. GLP-1 mediates antiapoptotic effect by phosphorylating Bad through a beta-arrestin 1-mediated ERK1/2 activation in pancreatic beta-cells.

    PubMed

    Quoyer, Julie; Longuet, Christine; Broca, Christophe; Linck, Nathalie; Costes, Safia; Varin, Elodie; Bockaert, Joël; Bertrand, Gyslaine; Dalle, Stéphane

    2010-01-15

    Strategies based on activating GLP-1 receptor (GLP-1R) are intensively developed for the treatment of type 2 diabetes. The exhaustive knowledge of the signaling pathways linked to activated GLP-1R within the beta-cells is of major importance. In beta-cells, GLP-1 activates the ERK1/2 cascade by diverse pathways dependent on either Galpha(s)/cAMP/cAMP-dependent protein kinase (PKA) or beta-arrestin 1, a scaffold protein. Using pharmacological inhibitors, beta-arrestin 1 small interfering RNA, and islets isolated from beta-arrestin 1 knock-out mice, we demonstrate that GLP-1 stimulates ERK1/2 by two temporally distinct pathways. The PKA-dependent pathway mediates rapid and transient ERK1/2 phosphorylation that leads to nuclear translocation of the activated kinases. In contrast, the beta-arrestin 1-dependent pathway produces a late ERK1/2 activity that is restricted to the beta-cell cytoplasm. We further observe that GLP-1 phosphorylates the cytoplasmic proapoptotic protein Bad at Ser-112 but not at Ser-155. We find that the beta-arrestin 1-dependent ERK1/2 activation engaged by GLP-1 mediates the Ser-112 phosphorylation of Bad, through p90RSK activation, allowing the association of Bad with the scaffold protein 14-3-3, leading to its inactivation. beta-Arrestin 1 is further found to mediate the antiapoptotic effect of GLP-1 in beta-cells through the ERK1/2-p90RSK-phosphorylation of Bad. This new regulatory mechanism engaged by activated GLP-1R involving a beta-arrestin 1-dependent spatiotemporal regulation of the ERK1/2-p90RSK activity is now suspected to participate in the protection of beta-cells against apoptosis. Such signaling mechanism may serve as a prototype to generate new therapeutic GLP-1R ligands.

  16. Superior reductions in hepatic steatosis and fibrosis with co-administration of a glucagon-like peptide-1 receptor agonist and obeticholic acid in mice.

    PubMed

    Jouihan, Hani; Will, Sarah; Guionaud, Silvia; Boland, Michelle L; Oldham, Stephanie; Ravn, Peter; Celeste, Anthony; Trevaskis, James L

    2017-11-01

    Nonalcoholic steatohepatitis (NASH) is an unmet need associated with metabolic syndrome. There are no approved therapies for NASH; however, glucagon-like peptide-1 receptor (GLP-1R) and farnesoid-X receptor (FXR) agonists are promising drug targets. We investigated the therapeutic effects of co-administration of a GLP-1R agonist, IP118, with FXR agonist obeticholic acid (OCA) in mice. OCA and IP118 alone and in combination were sub-chronically administered to Lep ob /Lep ob mice with diet-induced NASH or diet-induced obese (DIO) mice. Metabolic (body weight and glucose) and liver (biochemical and histological) endpoints were assessed. NASH severity in Lep ob /Lep ob mice was graded using a customized integrated scoring system. OCA reduced liver weight and lipid in NASH mice (both by -17%) but had no effect on plasma ALT or AST levels. In contrast, IP118 significantly reduced liver weight (-21%), liver lipid (-15%), ALT (-29%), and AST (-27%). The combination of OCA + IP118 further reduced liver weight (-29%), liver lipid (-22%), ALT (-39%), and AST (-36%). Combination therapy was superior to monotherapies in reducing hepatic steatosis, inflammation, and fibrosis. Hepatic improvements with IP118 and OCA + IP118 were associated with reduced body weight (-4.3% and -3.5% respectively) and improved glycemic control in OCA + IP118-treated mice. In DIO mice, OCA + IP118 co-administration reduced body weight (-25.3%) to a greater degree than IP118 alone (-12.5%) and further improved glucose tolerance and reduced hepatic lipid. Our data suggest a complementary or synergistic therapeutic effect of GLP-1R and FXR agonism in mouse models of metabolic disease and NASH. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  17. Molecular mechanisms redirecting the GLP-1 receptor signalling profile in pancreatic β-cells during type 2 diabetes.

    PubMed

    Roussel, Morgane; Mathieu, Julia; Dalle, Stéphane

    2016-05-01

    Treatments with β-cell preserving properties are essential for the management of type 2 diabetes (T2D), and the new therapeutic avenues, developed over the last years, rely on the physiological role of glucagon-like peptide-1 (GLP-1). Sustained pharmacological levels of GLP-1 are achieved by subcutaneous administration of GLP-1 analogues, while transient and lower physiological levels of GLP-1 are attained following treatment with inhibitors of dipeptidylpeptidase 4 (DPP4), an endoprotease which degrades the peptide. Both therapeutic classes display a sustained and durable hypoglycaemic action in patients with T2D. However, the GLP-1 incretin effect is known to be reduced in patients with T2D, and GLP-1 analogues and DPP4 inhibitors were shown to lose their effectiveness over time in some patients. The pathological mechanisms behind these observations can be either a decrease in GLP-1 secretion from intestinal L-cells and, as a consequence, a reduction in GLP-1 plasma concentrations, combined or not with a reduced action of GLP-1 in the β-cell, the so-called GLP-1 resistance. Much evidence for a GLP-1 resistance of the β-cell in subjects with T2D have emerged. Here, we review the potential roles of the genetic background, the hyperglycaemia, the hyperlipidaemia, the prostaglandin E receptor 3, the nuclear glucocorticoid receptor, the GLP-1R desensitization and internalisation processes, and the β-arrestin-1 expression levels on GLP-1 resistance in β-cells during T2D.

  18. High fat diet and GLP-1 drugs induce pancreatic injury in mice

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rouse, Rodney, E-mail: rodney.rouse@fda.hhs.gov; Xu, Lin; Stewart, Sharron

    Glucagon Like Peptide-1 (GLP-1) drugs are currently used to treat type-2 diabetes. Safety concerns for increased risk of pancreatitis and pancreatic ductal metaplasia have accompanied these drugs. High fat diet (HFD) is a type-2 diabetes risk factor that may affect the response to GLP-1 drug treatment. The objective of the present study was to investigate the effects of diet and GLP-1 based drugs on the exocrine pancreas in mice. Experiments were designed in a mouse model of insulin resistance created by feeding a HFD or standard diet (STD) for 6 weeks. The GLP-1 drugs, sitagliptin (SIT) and exenatide (EXE) weremore » administered once daily for additional 6 weeks in both mice fed HFD or STD. The results showed that body weight, blood glucose levels, and serum levels of pro-inflammatory cytokines (TNFα, IL-1β, and KC) were significantly greater in HFD mice than in STD mice regardless of GLP-1 drug treatment. The semi-quantitative grading showed that pancreatic changes were significantly greater in EXE and SIT-treated mice compared to control and that HFD exacerbated spontaneous exocrine pancreatic changes seen in saline-treated mice on a standard diet. Exocrine pancreatic changes identified in this study included acinar cell injury (hypertrophy, autophagy, apoptosis, necrosis, and atrophy), vascular injury, interstitial edema and inflammation, fat necrosis, and duct changes. These findings support HFD as a risk factor to increased susceptibility/severity for acute pancreatitis and indicate that GLP-1 drugs cause pancreatic injury that can be exacerbated in a HFD environment.« less

  19. Incretin therapies: highlighting common features and differences in the modes of action of glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors.

    PubMed

    Nauck, M

    2016-03-01

    Over the last few years, incretin-based therapies have emerged as important agents in the treatment of type 2 diabetes (T2D). These agents exert their effect via the incretin system, specifically targeting the receptor for the incretin hormone glucagon-like peptide 1 (GLP-1), which is partly responsible for augmenting glucose-dependent insulin secretion in response to nutrient intake (the 'incretin effect'). In patients with T2D, pharmacological doses/concentrations of GLP-1 can compensate for the inability of diabetic β cells to respond to the main incretin hormone glucose-dependent insulinotropic polypeptide, and this is therefore a suitable parent compound for incretin-based glucose-lowering medications. Two classes of incretin-based therapies are available: GLP-1 receptor agonists (GLP-1RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors. GLP-1RAs promote GLP-1 receptor (GLP-1R) signalling by providing GLP-1R stimulation through 'incretin mimetics' circulating at pharmacological concentrations, whereas DPP-4 inhibitors prevent the degradation of endogenously released GLP-1. Both agents produce reductions in plasma glucose and, as a result of their glucose-dependent mode of action, this is associated with low rates of hypoglycaemia; however, there are distinct modes of action resulting in differing efficacy and tolerability profiles. Furthermore, as their actions are not restricted to stimulating insulin secretion, these agents have also been associated with additional non-glycaemic benefits such as weight loss, improvements in β-cell function and cardiovascular risk markers. These attributes have made incretin therapies attractive treatments for the management of T2D and have presented physicians with an opportunity to tailor treatment plans. This review endeavours to outline the commonalities and differences among incretin-based therapies and to provide guidance regarding agents most suitable for treating T2D in individual patients. © 2015 The Authors

  20. Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces Alzheimer disease-associated tau hyperphosphorylation in the hippocampus of rats with type 2 diabetes.

    PubMed

    Xu, Weijie; Yang, Yan; Yuan, Gang; Zhu, Wenjun; Ma, Delin; Hu, Shuhong

    2015-02-01

    Impaired insulin signaling pathway in the brain in type 2 diabetes (T2D) is a risk factor for Alzheimer disease (AD). Glucagon-like peptide-1 (GLP-1) and its receptor agonist are widely used for treatment of T2D. Here we studied whether the effects of exendin-4 (EX-4), a long-lasting GLP-1 receptor agonist, could reduce the risk of AD in T2D. Type 2 diabetes rats were injected with EX-4 for 28 consecutive days. Blood glucose and insulin levels, as well as GLP-1 and insulin in cerebrospinal fluid, were determined during the experiment. The phosphorylation level of tau at individual phosphorylation sites, the activities of phosphatidylinositol 3 kinase/protein kinase B (PI3K/AKT), and glycogen synthase kinase-3β (GSK-3β) were analyzed with Western blots. The levels of phosphorylated tau protein at site Ser199/202 and Thr217 level in the hippocampus of T2D rats were found to be raised notably and evidently decreased after EX-4 intervention. In addition, brain insulin signaling pathway was ameliorated after EX-4 treatment, and this result was reflected by a decreased activity of PI3K/AKT and an increased activity of GSK-3β in the hippocampus of T2D rats as well as a rise in PI3K/AKT activity and a decline in GSK-3β activity after 4 weeks intervention of EX-4. These results demonstrate that multiple days with EX-4 appears to prevent the hyperphosphorylation of AD-associated tau protein due to increased insulin signaling pathway in the brain. These findings support the potential use of GLP-1 for the prevention and treatment of AD in individuals with T2D.

  1. Neuroprotective effects of (Val8)GLP-1-Glu-PAL in the MPTP Parkinson's disease mouse model.

    PubMed

    Zhang, YanFang; Chen, YiMei; Li, Lin; Hölscher, Christian

    2015-10-15

    Glucagon-like peptide 1 (GLP-1) is a hormone and a growth factor. GLP-1 mimetics are currently on the market as treatments for type 2 diabetes. They also have shown neuroprotective properties in animal models of neurodegenerative disorders. In addition, the GLP-1 mimetic exendin-4 has shown protective effects in animal models of Parkinson's disease (PD), and a first clinical trial in PD patients showed promising results. (Val8)GLP-1-glu-PAL is a new GLP-1 analogue which has a longer biological half-life than exendin-4. We previously showed that (Val8)GLP-1-glu-PAL has neuroprotective properties. Here we tested the drug in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. MPTP was injected (30mg/kg i.p.) along with (Val8)GLP-1-glu-PAL (25nmol/kg i.p.) once-daily for 8 days. (Val8)GLP-1-glu-PAL showed good effects in preventing the MPTP-induced motor impairment (Rotarod, open field locomotion, swim test), reduction in tyrosine hydroxylase levels (dopamine synthesis) in the substantia nigra, a reduction of activated caspase 3 levels, of TUNEL positive cell numbers, of the pro-apoptotic signaling molecule BAX and an increase in the growth signaling molecule Bcl-2. The results demonstrate that (Val8)GLP-1-glu-PAL shows promise as a novel treatment of PD. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. GLP-1 promotes mitochondrial metabolism in vascular smooth muscle cells by enhancing endoplasmic reticulum-mitochondria coupling.

    PubMed

    Morales, Pablo E; Torres, Gloria; Sotomayor-Flores, Cristian; Peña-Oyarzún, Daniel; Rivera-Mejías, Pablo; Paredes, Felipe; Chiong, Mario

    2014-03-28

    Incretin GLP-1 has important metabolic effects on several tissues, mainly through the regulation of glucose uptake and usage. One mechanism for increasing cell metabolism is modulating endoplasmic reticulum (ER)-mitochondria communication, as it allows for a more efficient transfer of Ca(2+) into the mitochondria, thereby increasing activity. Control of glucose metabolism is essential for proper vascular smooth muscle cell (VSMC) function. GLP-1 has been shown to produce varied metabolic actions, but whether it regulates glucose metabolism in VSMC remains unknown. In this report, we show that GLP-1 increases mitochondrial activity in the aortic cell line A7r5 by increasing ER-mitochondria coupling. GLP-1 increases intracellular glucose and diminishes glucose uptake without altering glycogen content. ATP, mitochondrial potential and oxygen consumption increase at 3h of GLP-1 treatment, paralleled by increased Ca(2+) transfer from the ER to the mitochondria. Furthermore, GLP-1 increases levels of Mitofusin-2 (Mfn2), an ER-mitochondria tethering protein, via a PKA-dependent mechanism. Accordingly, PKA inhibition and Mfn2 down-regulation prevented mitochondrial Ca(2+) increases in GLP-1 treated cells. Inhibiting both Ca(2+) release from the ER and Ca(2+) entry into mitochondria as well as diminishing Mfn2 levels blunted the increase in mitochondrial activity in response to GLP-1. Altogether, these results strongly suggest that GLP-1 increases ER-mitochondria communication in VSMC, resulting in higher mitochondrial activity. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Physiological Gut Oxygenation Alters GLP-1 Secretion from the Enteroendocrine Cell Line STC-1.

    PubMed

    Kondrashina, Alina; Papkovsky, Dmitri; Giblin, Linda

    2018-02-01

    Enteroendocrine cell lines are routinely assayed in simple buffers at ≈20% oxygen to screen foods for bioactives that boost satiety hormone levels. However, in vivo, enteroendocrine cells are exposed to different phases of food digestion and function at low oxygen concentration, ranging from 7.5% in the stomach to 0.5% in the colon-rectal junction. The objective of this study is to investigate the effect of physiologically relevant O 2 concentrations of the gut on the production and secretion of the satiety hormone, glucagon-like peptide 1 (GLP-1), from the murine enteroendocrine cell line, secretin tumor cell line (STC-1), in response to dairy macronutrients as they transit the gut. GLP-1 exocytosis from STC-1 cells is influenced by both oxygen concentration and by individual macronutrients. At low oxygen, STC-1 cell viability is significantly improved for all macronutrient stimulations and cyclic adenosine monophosphate levels are dampened. GLP-1 secretion from STC-1 cells is influenced by both the phase of yogurt digestion and corresponding O 2 concentration. Atmospheric oxygen at 4.5% combined with upper gastric digesta, which simulates ileum conditions, yields the highest GLP-1 response. This demonstrates the importance of considering physiological oxygen levels and food digestion along gastrointestinal tract for reliable in vitro analysis of gut hormone secretion. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Effects of E2HSA, a Long-Acting Glucagon Like Peptide-1 Receptor Agonist, on Glycemic Control and Beta Cell Function in Spontaneous Diabetic db/db Mice.

    PubMed

    Hou, Shaocong; Li, Caina; Huan, Yi; Liu, Shuainan; Liu, Quan; Sun, Sujuan; Jiang, Qian; Jia, Chunming; Shen, Zhufang

    2015-01-01

    Glucagon like peptide-1 (GLP-1) receptor agonists such as exendin-4 have been widely used but their short half-life limits their therapeutic value. The recombinant protein, E2HSA, is a novel, long-acting GLP-1 receptor agonist generated by the fusion of exendin-4 with human serum albumin. In mouse pancreatic NIT-1 cells, E2HSA activated GLP-1 receptor with similar efficacy as exendin-4. After single-dose administration in ICR mice, E2HSA showed prolonged glucose lowering effects which lasted up to four days and extended inhibition on gastric emptying for at least 72 hours. Chronic E2HSA treatment in db/db mice significantly improved glucose tolerance, reduced elevated nonfasting and fasting plasma glucose levels, and also decreased HbA1c levels. E2HSA also increased insulin secretion and decreased body weight and appetite. Furthermore, immunofluorescence analysis showed that E2HSA increased β-cell area, improved islet morphology, and reduced β-cell apoptosis. In accordance with the promotion of β-cell function and survival, E2HSA upregulated genes such as Irs2, Pdx-1, Nkx6.1, and MafA and downregulated the expression levels of FoxO1 and proapoptotic Bcl-2 family proteins. In conclusion, with prolonged glucose lowering effects and promoting β-cell function and survival, the fusion protein, E2HSA, is a promising new therapeutic for once weekly treatment of type 2 diabetes.

  5. Effects of E2HSA, a Long-Acting Glucagon Like Peptide-1 Receptor Agonist, on Glycemic Control and Beta Cell Function in Spontaneous Diabetic db/db Mice

    PubMed Central

    Hou, Shaocong; Li, Caina; Liu, Shuainan; Liu, Quan; Sun, Sujuan; Jia, Chunming; Shen, Zhufang

    2015-01-01

    Glucagon like peptide-1 (GLP-1) receptor agonists such as exendin-4 have been widely used but their short half-life limits their therapeutic value. The recombinant protein, E2HSA, is a novel, long-acting GLP-1 receptor agonist generated by the fusion of exendin-4 with human serum albumin. In mouse pancreatic NIT-1 cells, E2HSA activated GLP-1 receptor with similar efficacy as exendin-4. After single-dose administration in ICR mice, E2HSA showed prolonged glucose lowering effects which lasted up to four days and extended inhibition on gastric emptying for at least 72 hours. Chronic E2HSA treatment in db/db mice significantly improved glucose tolerance, reduced elevated nonfasting and fasting plasma glucose levels, and also decreased HbA1c levels. E2HSA also increased insulin secretion and decreased body weight and appetite. Furthermore, immunofluorescence analysis showed that E2HSA increased β-cell area, improved islet morphology, and reduced β-cell apoptosis. In accordance with the promotion of β-cell function and survival, E2HSA upregulated genes such as Irs2, Pdx-1, Nkx6.1, and MafA and downregulated the expression levels of FoxO1 and proapoptotic Bcl-2 family proteins. In conclusion, with prolonged glucose lowering effects and promoting β-cell function and survival, the fusion protein, E2HSA, is a promising new therapeutic for once weekly treatment of type 2 diabetes. PMID:26351642

  6. GLP-1 and GIP Levels in Patients With Hyperthyroidism: The Effect of Antithyroid Treatment.

    PubMed

    Cira, Duygu Kalkan; Sari, Ramazan; Ozdem, Sebahat; Yilmaz, Nusret; Bozkurt, Selen

    2017-08-01

    Incretin hormones (glucagon-like peptide-1 [GLP-1] and gastric inhibitory polypeptide [GIP]) may play a role in the development of glucose intolerance and hyperglycemia in patients with hyperthyroidism. We aimed to assess both incretin levels and treatment-induced changes in incretin levels in those with hyperthyroidism. A total of 24 subjects (12 with hyperthyroidism and 12 healthy) were enrolled in the study. Oral glucose tolerance test was performed and serum glucose, insulin GLP1, and GIP levels were evaluated at 0 (baseline), 30, 60, 90, and 120 minutes using ELISA. Measurements were repeated after euthyroidism was reached in subjects with hyperthyroidism. The baseline glucose level was higher in those with hyperthyroidism compared with controls ( P = 0.03). GLP-1 and GIP responses to oral glucose load did not differ significantly between those with hyperthyroidism and controls. Peak GLP-1 and GIP levels were reached in both groups at 60 and 90 minutes, respectively. Areas under the curve (AUCs) for GLP1 and GIP were similar in those with hyperthyroidism and controls. Although GLP-1 and GIP levels did not change before and after antithyroid treatment in subjects with hyperthyroidism, time to peak GLP-1 and GIP levels were reached at 30 minutes after euthyroid state was achieved. Reversal of hyperthyroid to euthyroid status did not induce significant changes in AUCs for incretins. The findings of the present study suggest that the total incretin response to oral glucose load is preserved in patients with hypertyhroidism, but peak incretin responses may change after achieving euthyroid state.

  7. Discovery of 3-aryl-4-isoxazolecarboxamides as TGR5 receptor agonists.

    PubMed

    Evans, Karen A; Budzik, Brian W; Ross, Sean A; Wisnoski, David D; Jin, Jian; Rivero, Ralph A; Vimal, Mythily; Szewczyk, George R; Jayawickreme, Channa; Moncol, David L; Rimele, Thomas J; Armour, Susan L; Weaver, Susan P; Griffin, Robert J; Tadepalli, Sarva M; Jeune, Michael R; Shearer, Todd W; Chen, Zibin B; Chen, Lihong; Anderson, Donald L; Becherer, J David; De Los Frailes, Maite; Colilla, Francisco Javier

    2009-12-24

    A series of 3-aryl-4-isoxazolecarboxamides identified from a high-throughput screening campaign as novel, potent small molecule agonists of the human TGR5 G-protein coupled receptor is described. Subsequent optimization resulted in the rapid identification of potent exemplars 6 and 7 which demonstrated improved GLP-1 secretion in vivo via an intracolonic dose coadministered with glucose challenge in a canine model. These novel TGR5 receptor agonists are potentially useful therapeutics for metabolic disorders such as type II diabetes and its associated complications.

  8. A Novel GLP1 Receptor Interacting Protein ATP6ap2 Regulates Insulin Secretion in Pancreatic Beta Cells*

    PubMed Central

    Dai, Feihan F.; Bhattacharjee, Alpana; Liu, Ying; Batchuluun, Battsetseg; Zhang, Ming; Wang, Xinye Serena; Huang, Xinyi; Luu, Lemieux; Zhu, Dan; Gaisano, Herbert; Wheeler, Michael B.

    2015-01-01

    GLP1 activates its receptor, GLP1R, to enhance insulin secretion. The activation and transduction of GLP1R requires complex interactions with a host of accessory proteins, most of which remain largely unknown. In this study, we used membrane-based split ubiquitin yeast two-hybrid assays to identify novel GLP1R interactors in both mouse and human islets. Among these, ATP6ap2 (ATPase H+-transporting lysosomal accessory protein 2) was identified in both mouse and human islet screens. ATP6ap2 was shown to be abundant in islets including both alpha and beta cells. When GLP1R and ATP6ap2 were co-expressed in beta cells, GLP1R was shown to directly interact with ATP6ap2, as assessed by co-immunoprecipitation. In INS-1 cells, overexpression of ATP6ap2 did not affect insulin secretion; however, siRNA knockdown decreased both glucose-stimulated and GLP1-induced insulin secretion. Decreases in GLP1-induced insulin secretion were accompanied by attenuated GLP1 stimulated cAMP accumulation. Because ATP6ap2 is a subunit required for V-ATPase assembly of insulin granules, it has been reported to be involved in granule acidification. In accordance with this, we observed impaired insulin granule acidification upon ATP6ap2 knockdown but paradoxically increased proinsulin secretion. Importantly, as a GLP1R interactor, ATP6ap2 was required for GLP1-induced Ca2+ influx, in part explaining decreased insulin secretion in ATP6ap2 knockdown cells. Taken together, our findings identify a group of proteins that interact with the GLP1R. We further show that one interactor, ATP6ap2, plays a novel dual role in beta cells, modulating both GLP1R signaling and insulin processing to affect insulin secretion. PMID:26272612

  9. The Sigma-1 Receptor Antagonist, S1RA, Reduces Stroke Damage, Ameliorates Post-Stroke Neurological Deficits and Suppresses the Overexpression of MMP-9.

    PubMed

    Sánchez-Blázquez, Pilar; Pozo-Rodrigálvarez, Andrea; Merlos, Manuel; Garzón, Javier

    2018-06-01

    The glutamate N-methyl-D-aspartate receptor (NMDAR) plays an essential role in the excitotoxic neural damage that follows ischaemic stroke. Because the sigma-1 receptor (σ1R) can regulate NMDAR transmission, exogenous and putative endogenous regulators of σ1R have been investigated using animal models of ischaemic stroke. As both agonists and antagonists provide some neural protection, the selective involvement of σ1Rs in these effects has been questioned. The availability of S1RA (E-52862/MR309), a highly selective σ1R antagonist, prompted us to explore its therapeutic potential in an animal model of focal cerebral ischaemia. Mice were subjected to right middle cerebral artery occlusion (MCAO), and post-ischaemic infarct volume and neurological deficits were determined across a range of intervals after the stroke-inducing surgery. Intracerebroventricular or intravenous treatment with S1RA significantly reduced the cerebral infarct size and neurological deficits caused by permanent MCAO (pMCAO). Compared with the control/sham-operated mice, the neuroprotective effects of S1RA were observed when delivered up to 5 h prior to surgery and 3 h after ischaemic onset. Interestingly, neither mice with the genetic deletion of σ1R nor wild-type mice that were pre-treated with the σ1R agonist PRE084 showed beneficial effects after S1RA administration with regard to stroke infarction. S1RA-treated mice showed faster behavioural recovery from stroke; this finding complements the significant decreases in matrix metalloproteinase-9 (MMP-9) expression and reactive astrogliosis surrounding the infarcted cortex. Our data indicate that S1RA, via σ1R, holds promising potential for clinical application as a therapeutic agent for ischaemic stroke.

  10. Altered glucose metabolism after bariatric surgery: What's GLP-1 got to do with it?

    PubMed

    Smith, Eric P; Polanco, Georgina; Yaqub, Abid; Salehi, Marzieh

    2018-06-01

    Bariatric surgery is an effective treatment for obesity. The two widely performed weight-loss procedures, Roux-en-Y gastric bypass (GB) and sleeve gastrectomy (SG), alter postprandial glucose pattern and enhance gut hormone secretion immediately after surgery before significant weight loss. This weight-loss independent glycemic effects of GB has been attributed to an accelerated nutrient transit from stomach pouch to the gut and enhanced secretion of insulinotropic gut factors; in particular, glucagon-like peptide-1 (GLP-1). Meal-induced GLP-1 secretion is as much as tenfold higher in patients after GB compared to non-surgical individuals and inhibition of GLP-1 action during meals reduces postprandial hyperinsulinemia after GB two to three times more than that in persons without surgery. Moreover, in a subgroup of patients with the late complication of postprandial hyperinsulinemic hypoglycemia after GB, GLP1R blockade reverses hypoglycemia by reducing meal stimulated insulin secretion. The role of enteroinsular axis activity after SG, an increasingly popular alternative to GB, is less understood but, similar to GB, SG accelerates nutrient delivery to the intestine, improves glucose tolerance, and increases postprandial GLP-1 secretion. This review will focus on the current evidence for and against the role of GLP-1 on glycemic effects of GB and will also highlight differences between GB and SG. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Bariatric surgery may reduce the risk of Alzheimer's diseases through GLP-1 mediated neuroprotective effects.

    PubMed

    Keshava, Hari B; Mowla, Ashkan; Heinberg, Leslie J; Schauer, Philip R; Brethauer, Stacy A; Aminian, Ali

    2017-07-01

    Obesity and diabetes are associated with deficits in multiple neurocognitive domains and increased risk for dementia. Over the last two decades, there has been a significant increase in bariatric and metabolic surgery worldwide, driven by rising intertwined pandemics of obesity and diabetes, along with improvement in surgical techniques. Patients undergoing bariatric surgery achieve a significant decrease in their excess weight and a multitude of sequela associated with obesity, diabetes, and metabolic syndrome. Glucagon-like peptide 1 (GLP-1) is an intestinal peptide that has been implicated as one of the weight loss-independent mechanisms in how bariatric surgery affects type 2 diabetes. GLP-1 improves insulin secretion, inhibits apoptosis and induce pancreatic islet neogenesis, promotes satiety, and can regulate heart rate and blood pressure. Moreover, numerous studies have demonstrated potential neuroprotective and neurotrophic effects of GLP-1. Increased GLP-1 activity has been shown to increase cortical activity, promote neuronal growth, and inhibit neuronal degeneration. Specifically, in experimental studies on Alzheimer's disease, GLP-1 decreases amyloid deposition and neurofibrillary tangles. Furthermore, recent studies have also suggested that GLP-1 based therapies, new class of antidiabetic drugs, have favorable effects on neurodegenerative disorders such as Alzheimer's disease. We present a hypothesis that bariatric surgery can help delay or even prevent the onset of Alzheimer's disease in long-term by increasing the levels of GLP-1. This hypothesis has a potential for many studies from basic science projects to large population studies to fully understand the neurological and cognitive consequences of bariatric surgery and associated rise in GLP-1. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. The germin-like protein OsGLP2-1 enhances resistance to fungal blast and bacterial blight in rice.

    PubMed

    Liu, Qing; Yang, Jianyuan; Yan, Shijuan; Zhang, Shaohong; Zhao, Junliang; Wang, Wenjuan; Yang, Tifeng; Wang, Xiaofei; Mao, Xingxue; Dong, Jingfang; Zhu, Xiaoyuan; Liu, Bin

    2016-11-01

    This is the first report that GLP gene (OsGLP2-1) is involved in panicle blast and bacterial blight resistance in rice. In addition to its resistance to blast and bacterial blight, OsGLP2-1 has also been reported to co-localize with a QTLs for sheath blight resistance in rice. These suggest that the disease resistance provided by OsGLP2-1 is quantitative and broad spectrum. Its good resistance to these major diseases in rice makes it to be a promising target in rice breeding. Rice (Oryza sativa) blast caused by Magnaporthe oryzae and bacterial blight caused by Xanthomonas oryzae pv. oryzae are the two most destructive rice diseases worldwide. Germin-like protein (GLP) gene family is one of the important defense gene families which have been reported to be involved in disease resistance in plants. Although GLP proteins have been demonstrated to positively regulate leaf blast resistance in rice, their involvement in resistance to panicle blast and bacterial blight, has not been reported. In this study, we reported that one of the rice GLP genes, OsGLP2-1, was significantly induced by blast fungus. Overexpression of OsGLP2-1 quantitatively enhanced resistance to leaf blast, panicle blast and bacterial blight. The temporal and spatial expression analysis revealed that OsGLP2-1is highly expressed in leaves and panicles and sub-localized in the cell wall. Compared with empty vector transformed (control) plants, the OsGLP2-1 overexpressing plants exhibited higher levels of H 2 O 2 both before and after pathogen inoculation. Moreover, OsGLP2-1 was significantly induced by jasmonic acid (JA). Overexpression of OsGLP2-1 induced three well-characterized defense-related genes which are associated in JA-dependent pathway after pathogen infection. Higher endogenous level of JA was also identified in OsGLP2-1 overexpressing plants than in control plants both before and after pathogen inoculation. Together, these results suggest that OsGLP2-1 functions as a positive regulator to

  13. GLP-1-oestrogen attenuates hyperphagia and protects from beta cell failure in diabetes-prone New Zealand obese (NZO) mice.

    PubMed

    Schwenk, Robert W; Baumeier, Christian; Finan, Brian; Kluth, Oliver; Brauer, Christine; Joost, Hans-Georg; DiMarchi, Richard D; Tschöp, Matthias H; Schürmann, Annette

    2015-03-01

    Oestrogens have previously been shown to exert beta cell protective, glucose-lowering effects in mouse models. Therefore, the recent development of a glucagon-like peptide-1 (GLP-1)-oestrogen conjugate, which targets oestrogen into cells expressing GLP-1 receptors, offers an opportunity for a cell-specific and enhanced beta cell protection by oestrogen. The purpose of this study was to compare the effects of GLP-1 and GLP-1-oestrogen during beta cell failure under glucolipotoxic conditions. Male New Zealand obese (NZO) mice were treated with daily s.c. injections of GLP-1 and GLP-1-oestrogen, respectively. Subsequently, the effects on energy homeostasis and beta cell integrity were measured. In order to clarify the targeting of GLP-1-oestrogen, transcription analyses of oestrogen-responsive genes in distinct tissues as well as microarray analyses in pancreatic islets were performed. In contrast to GLP-1, GLP-1-oestrogen significantly decreased food intake resulting in a substantial weight reduction, preserved normoglycaemia, increased glucose tolerance and enhanced beta cell protection. Analysis of hypothalamic mRNA profiles revealed elevated expression of Pomc and Leprb. In livers from GLP-1-oestrogen-treated mice, expression of lipogenic genes was attenuated and hepatic triacylglycerol levels were decreased. In pancreatic islets, GLP-1-oestrogen altered the mRNA expression to a pattern that was similar to that of diabetes-resistant NZO females. However, conventional oestrogen-responsive genes were not different, indicating rather indirect protection of pancreatic beta cells. GLP-1-oestrogen efficiently protects NZO mice against carbohydrate-induced beta cell failure by attenuation of hyperphagia. In this regard, targeted delivery of oestrogen to the hypothalamus by far exceeds the anorexigenic capacity of GLP-1 alone.

  14. Liraglutide as adjunct to insulin treatment in type 1 diabetes does not interfere with glycaemic recovery or gastric emptying rate during hypoglycaemia: A randomized, placebo-controlled, double-blind, parallel-group study.

    PubMed

    Frandsen, Christian S; Dejgaard, Thomas F; Andersen, Henrik U; Holst, Jens J; Hartmann, Bolette; Thorsteinsson, Birger; Madsbad, Sten

    2017-06-01

    Glucagon-like peptide-1 receptor agonist (GLP-1RA) therapy is a potential treatment as adjunct to insulin in type 1 diabetes (T1D). However, GLP-1RAs inhibit glucagon secretion and delay the gastric emptying (GE) rate and may impair recovery from hypoglycaemia. We evaluated the effect of the GLP-1RA liraglutide on counterregulatory responses and GE rate during hypoglycaemia in persons with T1D. In a 12-week, randomized, double-blind, placebo-controlled study, 20 patients aged >18 years with T1D and HbA1c ≥8% (64 mmol/mol) were randomly assigned (1:1) to liraglutide 1.2 mg once daily or placebo as add-on to insulin treatment. Before and at end of treatment a hypoglycaemic clamp (plasma glucose target 2.5 mmol/L) was carried out, followed by a liquid meal. Primary endpoint was change in GE rate (evaluated by area under the paracetamol curve and time to peak). Secondary endpoints included changes in glycaemic recovery, counter-regulatory hormones, pancreatic polypeptide (PP), GLP-1, blood pressure and heart rate. During the period June 2013 to October 2014, 20 patients were enrolled. After 12 weeks of treatment, changes in GE rates did not differ significantly between groups ( P  = .96), with no significant changes from baseline, whether evaluated from AUCs or time to peak. The secondary endpoints, glycaemic recovery, counter-regulatory hormone responses, systolic blood pressure and GLP-1 and PP responses, were also similar. Heart rate increased with liraglutide from 69 ± 4 to 80 ± 5 beats/min ( P  = .02). Liraglutide does not compromise glycaemic recovery, GE rate or counter-regulatory hormone responses in T1D patients during hypoglycaemia. No treatment-related safety issues were identified. © 2016 John Wiley & Sons Ltd.

  15. Linear {GLP}-algebras and their elementary theories

    NASA Astrophysics Data System (ADS)

    Pakhomov, F. N.

    2016-12-01

    The polymodal provability logic {GLP} was introduced by Japaridze in 1986. It is the provability logic of certain chains of provability predicates of increasing strength. Every polymodal logic corresponds to a variety of polymodal algebras. Beklemishev and Visser asked whether the elementary theory of the free {GLP}-algebra generated by the constants \\mathbf{0}, \\mathbf{1} is decidable [1]. For every positive integer n we solve the corresponding question for the logics {GLP}_n that are the fragments of {GLP} with n modalities. We prove that the elementary theory of the free {GLP}_n-algebra generated by the constants \\mathbf{0}, \\mathbf{1} is decidable for all n. We introduce the notion of a linear {GLP}_n-algebra and prove that all free {GLP}_n-algebras generated by the constants \\mathbf{0}, \\mathbf{1} are linear. We also consider the more general case of the logics {GLP}_α whose modalities are indexed by the elements of a linearly ordered set α: we define the notion of a linear algebra and prove the latter result in this case.

  16. Insulin and GLP-1 infusions demonstrate the onset of adipose-specific insulin resistance in a large fasting mammal: potential glucogenic role for GLP-1.

    PubMed

    Viscarra, Jose A; Rodriguez, Ruben; Vazquez-Medina, Jose Pablo; Lee, Andrew; Tift, Michael S; Tavoni, Stephen K; Crocker, Daniel E; Ortiz, Rudy M

    2013-08-01

    Prolonged food deprivation increases lipid oxidation and utilization, which may contribute to the onset of the insulin resistance associated with fasting. Because insulin resistance promotes the preservation of glucose and oxidation of fat, it has been suggested to be an adaptive response to food deprivation. However, fasting mammals exhibit hypoinsulinemia, suggesting that the insulin resistance-like conditions they experience may actually result from reduced pancreatic sensitivity to glucose/capacity to secrete insulin. To determine whether fasting results in insulin resistance or in pancreatic dysfunction, we infused early- and late-fasted seals (naturally adapted to prolonged fasting) with insulin (0.065 U/kg), and a separate group of late-fasted seals with low (10 pM/kg) or high (100 pM/kg) dosages of glucagon-like peptide-1 (GLP-1) immediately following a glucose bolus (0.5g/kg), and measured the systemic and cellular responses. Because GLP-1 facilitates glucose-stimulated insulin secretion, these infusions provide a method to assess pancreatic insulin-secreting capacity. Insulin infusions increased the phosphorylation of insulin receptor and Akt in adipose and muscle of early and late fasted seals; however the timing of the signaling response was blunted in adipose of late fasted seals. Despite the dose-dependent increases in insulin and increased glucose clearance (high dose), both GLP-1 dosages produced increases in plasma cortisol and glucagon, which may have contributed to the glucogenic role of GLP-1. Results suggest that fasting induces adipose-specific insulin resistance in elephant seal pups, while maintaining skeletal muscle insulin sensitivity, and therefore suggests that the onset of insulin resistance in fasting mammals is an evolved response to cope with prolonged food deprivation.

  17. Glucagon-like peptide-1 acutely affects renal blood flow and urinary flow rate in spontaneously hypertensive rats despite significantly reduced renal expression of GLP-1 receptors.

    PubMed

    Ronn, Jonas; Jensen, Elisa P; Wewer Albrechtsen, Nicolai J; Holst, Jens Juul; Sorensen, Charlotte M

    2017-12-01

    Glucagon-like peptide-1 (GLP-1) is an incretin hormone increasing postprandial insulin release. GLP-1 also induces diuresis and natriuresis in humans and rodents. The GLP-1 receptor is extensively expressed in the renal vascular tree in normotensive rats where acute GLP-1 treatment leads to increased mean arterial pressure (MAP) and increased renal blood flow (RBF). In hypertensive animal models, GLP-1 has been reported both to increase and decrease MAP. The aim of this study was to examine expression of renal GLP-1 receptors in spontaneously hypertensive rats (SHR) and to assess the effect of acute intrarenal infusion of GLP-1. We hypothesized that GLP-1 would increase diuresis and natriuresis and reduce MAP in SHR. Immunohistochemical staining and in situ hybridization for the GLP-1 receptor were used to localize GLP-1 receptors in the kidney. Sevoflurane-anesthetized normotensive Sprague-Dawley rats and SHR received a 20 min intrarenal infusion of GLP-1 and changes in MAP, RBF, heart rate, dieresis, and natriuresis were measured. The vasodilatory effect of GLP-1 was assessed in isolated interlobar arteries from normo- and hypertensive rats. We found no expression of GLP-1 receptors in the kidney from SHR. However, acute intrarenal infusion of GLP-1 increased MAP, RBF, dieresis, and natriuresis without affecting heart rate in both rat strains. These results suggest that the acute renal effects of GLP-1 in SHR are caused either by extrarenal GLP-1 receptors activating other mechanisms (e.g., insulin) to induce the renal changes observed or possibly by an alternative renal GLP-1 receptor. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  18. Physiology and emerging biochemistry of the glucagon-like peptide-1 receptor.

    PubMed

    Willard, Francis S; Sloop, Kyle W

    2012-01-01

    The glucagon-like peptide-1 (GLP-1) receptor is one of the best validated therapeutic targets for the treatment of type 2 diabetes mellitus (T2DM). Over several years, the accumulation of basic, translational, and clinical research helped define the physiologic roles of GLP-1 and its receptor in regulating glucose homeostasis and energy metabolism. These efforts provided much of the foundation for pharmaceutical development of the GLP-1 receptor peptide agonists, exenatide and liraglutide, as novel medicines for patients suffering from T2DM. Now, much attention is focused on better understanding the molecular mechanisms involved in ligand induced signaling of the GLP-1 receptor. For example, advancements in biophysical and structural biology techniques are being applied in attempts to more precisely determine ligand binding and receptor occupancy characteristics at the atomic level. These efforts should better inform three-dimensional modeling of the GLP-1 receptor that will help inspire more rational approaches to identify and optimize small molecule agonists or allosteric modulators targeting the GLP-1 receptor. This article reviews GLP-1 receptor physiology with an emphasis on GLP-1 induced signaling mechanisms in order to highlight new molecular strategies that help determine desired pharmacologic characteristics for guiding development of future nonpeptide GLP-1 receptor activators.

  19. Physiology and Emerging Biochemistry of the Glucagon-Like Peptide-1 Receptor

    PubMed Central

    Willard, Francis S.; Sloop, Kyle W.

    2012-01-01

    The glucagon-like peptide-1 (GLP-1) receptor is one of the best validated therapeutic targets for the treatment of type 2 diabetes mellitus (T2DM). Over several years, the accumulation of basic, translational, and clinical research helped define the physiologic roles of GLP-1 and its receptor in regulating glucose homeostasis and energy metabolism. These efforts provided much of the foundation for pharmaceutical development of the GLP-1 receptor peptide agonists, exenatide and liraglutide, as novel medicines for patients suffering from T2DM. Now, much attention is focused on better understanding the molecular mechanisms involved in ligand induced signaling of the GLP-1 receptor. For example, advancements in biophysical and structural biology techniques are being applied in attempts to more precisely determine ligand binding and receptor occupancy characteristics at the atomic level. These efforts should better inform three-dimensional modeling of the GLP-1 receptor that will help inspire more rational approaches to identify and optimize small molecule agonists or allosteric modulators targeting the GLP-1 receptor. This article reviews GLP-1 receptor physiology with an emphasis on GLP-1 induced signaling mechanisms in order to highlight new molecular strategies that help determine desired pharmacologic characteristics for guiding development of future nonpeptide GLP-1 receptor activators. PMID:22666230

  20. Active metabolite of GLP-1 mediates myocardial glucose uptake and improves left ventricular performance in conscious dogs with dilated cardiomyopathy.

    PubMed

    Nikolaidis, Lazaros A; Elahi, Dariush; Shen, You-Tang; Shannon, Richard P

    2005-12-01

    We have shown previously that the glucagon-like peptide-1 (GLP-1)-(7-36) amide increases myocardial glucose uptake and improves left ventricular (LV) and systemic hemodynamics in both conscious dogs with pacing-induced dilated cardiomyopathy (DCM) and humans with LV systolic dysfunction after acute myocardial infarction. However, GLP-1-(7-36) is rapidly degraded in the plasma to GLP-1-(9-36) by dipeptidyl peptidase IV (DPP IV), raising the issue of which peptide is the active moiety. By way of methodology, we compared the efficacy of a 48-h continuous intravenous infusion of GLP-1-(7-36) (1.5 pmol.kg(-1).min(-1)) to GLP-1-(9-36) (1.5 pmol.kg(-1).min(-1)) in 28 conscious, chronically instrumented dogs with pacing-induced DCM by measuring LV function and transmyocardial substrate uptake under basal and insulin-stimulated conditions using hyperinsulinemic-euglycemic clamps. As a result, dogs with DCM demonstrated myocardial insulin resistance under basal and insulin-stimulated conditions. Both GLP-1-(7-36) and GLP-1-(9-36) significantly reduced (P < 0.01) LV end-diastolic pressure [GLP-1-(7-36), 28 +/- 1 to 15 +/- 2 mmHg; GLP-1-(9-36), 29 +/- 2 to 16 +/- 1 mmHg] and significantly increased (P < 0.01) the first derivative of LV pressure [GLP-1-(7-36), 1,315 +/- 81 to 2,195 +/- 102 mmHg/s; GLP-1-(9-36), 1,336 +/- 77 to 2,208 +/- 68 mmHg] and cardiac output [GLP-1-(7-36), 1.5 +/- 0.1 to 1.9 +/- 0.1 l/min; GLP-1-(9-36), 2.0 +/- 0.1 to 2.4 +/- 0.05 l/min], whereas an equivolume infusion of saline had no effect. Both peptides increased myocardial glucose uptake but without a significant increase in plasma insulin. During the GLP-1-(9-36) infusion, negligible active (NH2-terminal) peptide was measured in the plasma. In conclusion, in DCM, GLP-1-(9-36) mimics the effects of GLP-1-(7-36) in stimulating myocardial glucose uptake and improving LV and systemic hemodynamics through insulinomimetic as opposed to insulinotropic effects. These data suggest that GLP-1-(9-36) amide is

  1. Myocardial regeneration in adriamycin cardiomyopathy by nuclear expression of GLP1 using ultrasound targeted microbubble destruction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Shuyuan; Chen, Jiaxi; Huang, Pintong

    Recently GLP-1 was found to have cardioprotective effects independent of those attributable to tight glycemic control. Methods and results: We employed ultrasound targeted microbubble destruction (UTMD) to deliver piggybac transposon plasmids encoding the GLP-1 gene with a nuclear localizing signal to rat hearts with adriamycin cardiomyopathy. After a single UTMD treatment, overexpression of transgenic GLP-1 was found in nuclei of rat heart cells with evidence that transfected cardiac cells had undergone proliferation. UTMD-GLP-1 gene therapy restored LV mass, fractional shortening index, and LV posterior wall diameter to nearly normal. Nuclear overexpression of GLP-1 by inducing phosphorylation of FoxO1-S256 and translocationmore » of FoxO1 from the nucleus to the cytoplasm significantly inactivated FoxO1 and activated the expression of cyclin D1 in nuclei of cardiac muscle cells. Reversal of adriamycin cardiomyopathy appeared to be mediated by dedifferentiation and proliferation of nuclear FoxO1-positive cardiac muscle cells with evidence of embryonic stem cell markers (OCT4, Nanog, SOX2 and c-kit), cardiac early differentiation markers (NKX2.5 and ISL-1) and cellular proliferation markers (BrdU and PHH3) after UTMD with GLP-1 gene therapy. Conclusions: Intranuclear myocardial delivery of the GLP-1gene can reverse established adriamycin cardiomyopathy by stimulating myocardial regeneration. - Highlights: • The activation of nuclear FoxO1 in cardiac muscle cells associated with adriamycin cardiomyopathy. • Myocardial nuclear GLP-1 stimulates myocardial regeneration and reverses adriamycin cardiomyopathy. • The process of myocardial regeneration associated with dedifferentiation and proliferation.« less

  2. Circulating GLP-1 in infants born small-for-gestational-age: breast-feeding versus formula-feeding.

    PubMed

    Díaz, M; Bassols, J; Sebastiani, G; López-Bermejo, A; Ibáñez, L; de Zegher, F

    2015-10-01

    Prenatal growth restraint associates with the risk for later diabetes, particularly if such restraint is followed by postnatal formula-feeding (FOF) rather than breast-feeding (BRF). Circulating incretins can influence the neonatal programming of hypothalamic setpoints for appetite and energy expenditure, and are thus candidate mediators of the long-term effects exerted by early nutrition. We have tested this concept by measuring (at birth and at age 4 months) the circulating concentrations of glucagon-like peptide-1 (GLP-1) in BRF infants born appropriate-for-gestational-age (AGA; n=63) and in small-for-gestational-age (SGA) infants receiving either BRF (n=28) or FOF (n=26). At birth, concentrations of GLP-1 were similar in AGA and SGA infants. At 4 months, pre-feeding GLP-1 concentrations were higher than at birth; SGA-BRF infants had GLP-1 concentrations similar to those in AGA-BRF infants but SGA-FOF infants had higher concentrations. In conclusion, nutrition appears to influence the circulating GLP-1 concentrations in SGA infants and may thereby modulate long-term diabetes risk.

  3. Quantitative Impact of Plasma Clearance and Down-regulation on GLP-1 Receptor Molecular Imaging.

    PubMed

    Zhang, Liang; Thurber, Greg M

    2016-02-01

    Quantitative molecular imaging of beta cell mass (BCM) would enable early detection and treatment monitoring of type 1 diabetes. The glucagon-like peptide-1 (GLP-1) receptor is an attractive target due to its beta cell specificity and cell surface location. We quantitatively investigated the impact of plasma clearance and receptor internalization on targeting efficiency in healthy B6 mice. Four exenatide-based probes were synthesized that varied in molecular weight, binding affinity, and plasma clearance. The GLP-1 receptor internalization rate and in vivo receptor expression were quantified. Receptor internalization (54,000 receptors/cell in vivo) decreased significantly within minutes, reducing the benefit of a slower-clearing agent. The multimers and albumin binding probes had higher kidney and liver uptake, respectively. Slow plasma clearance is beneficial for GLP-1 receptor peptide therapeutics. However, for exendin-based imaging of islets, down-regulation of the GLP-1 receptor and non-specific background uptake result in a higher target-to-background ratio for fast-clearing agents.

  4. Quantitative Impact of Plasma Clearance and Down-regulation on GLP-1 Receptor Molecular Imaging

    PubMed Central

    Zhang, Liang; Thurber, Greg M.

    2016-01-01

    Purpose Quantitative molecular imaging of beta cell mass (BCM) would enable early detection and treatment monitoring of type-1 diabetes. The glucagon like peptide-1 (GLP-1) receptor is an attractive target due to its beta cell specificity and cell surface location. We quantitatively investigated the impact of plasma clearance and receptor internalization on targeting efficiency in healthy B6 mice. Procedures Four exenatide-based probes were synthesized that varied in molecular weight, binding affinity, and plasma clearance. The GLP-1 receptor internalization rate and in vivo receptor expression were quantified. Results Receptor internalization (54,000 receptors/cell in vivo) decreased significantly within minutes, reducing the benefit of a slower clearing agent. The multimers and albumin binding probes had higher kidney and liver uptake, respectively. Conclusions Slow plasma clearance is beneficial for GLP-1 receptor peptide therapeutics. However, for exendin-based imaging of islets, downregulation of the GLP-1 receptor and non-specific background uptake result in a higher TBR for fast-clearing agents. PMID:26194012

  5. GLP-1 Receptor Stimulation of the Lateral Parabrachial Nucleus Reduces Food Intake: Neuroanatomical, Electrophysiological, and Behavioral Evidence

    PubMed Central

    Richard, Jennifer E.; Farkas, Imre; Anesten, Fredrik; Anderberg, Rozita H.; Dickson, Suzanne L.; Gribble, Fiona M.; Reimann, Frank; Jansson, John-Olov; Liposits, Zsolt

    2014-01-01

    The parabrachial nucleus (PBN) is a key nucleus for the regulation of feeding behavior. Inhibitory inputs from the hypothalamus to the PBN play a crucial role in the normal maintenance of feeding behavior, because their loss leads to starvation. Viscerosensory stimuli result in neuronal activation of the PBN. However, the origin and neurochemical identity of the excitatory neuronal input to the PBN remain largely unexplored. Here, we hypothesize that hindbrain glucagon-like peptide 1 (GLP-1) neurons provide excitatory inputs to the PBN, activation of which may lead to a reduction in feeding behavior. Our data, obtained from mice expressing the yellow fluorescent protein in GLP-1-producing neurons, revealed that hindbrain GLP-1-producing neurons project to the lateral PBN (lPBN). Stimulation of lPBN GLP-1 receptors (GLP-1Rs) reduced the intake of chow and palatable food and decreased body weight in rats. It also activated lPBN neurons, reflected by an increase in the number of c-Fos-positive cells in this region. Further support for an excitatory role of GLP-1 in the PBN is provided by electrophysiological studies showing a remarkable increase in firing of lPBN neurons after Exendin-4 application. We show that within the PBN, GLP-1R activation increased gene expression of 2 energy balance regulating peptides, calcitonin gene-related peptide (CGRP) and IL-6. Moreover, nearly 70% of the lPBN GLP-1 fibers innervated lPBN CGRP neurons. Direct intra-lPBN CGRP application resulted in anorexia. Collectively, our molecular, anatomical, electrophysiological, pharmacological, and behavioral data provide evidence for a functional role of the GLP-1R for feeding control in the PBN. PMID:25116706

  6. GLP-1 and estrogen conjugate acts in the supramammillary nucleus to reduce food-reward and body weight.

    PubMed

    Vogel, Heike; Wolf, Stefanie; Rabasa, Cristina; Rodriguez-Pacheco, Francisca; Babaei, Carina S; Stöber, Franziska; Goldschmidt, Jürgen; DiMarchi, Richard D; Finan, Brian; Tschöp, Matthias H; Dickson, Suzanne L; Schürmann, Annette; Skibicka, Karolina P

    2016-11-01

    The obesity epidemic continues unabated and currently available pharmacological treatments are not sufficiently effective. Combining gut/brain peptide, GLP-1, with estrogen into a conjugate may represent a novel, safe and potent, strategy to treat diabesity. Here we demonstrate that the central administration of GLP-1-estrogen conjugate reduced food reward, food intake, and body weight in rats. In order to determine the brain location of the interaction of GLP-1 with estrogen, we avail of single-photon emission computed tomography imaging of regional cerebral blood flow and pinpoint a brain site unexplored for its role in feeding and reward, the supramammillary nucleus (SUM) as a potential target of the conjugated GLP-1-estrogen. We confirm that conjugated GLP-1 and estrogen directly target the SUM with site-specific microinjections. Additional microinjections of GLP-1-estrogen into classic energy balance controlling nuclei, the lateral hypothalamus (LH) and the nucleus of the solitary tract (NTS) revealed that the metabolic benefits resulting from GLP-1-estrogen injections are mediated through the LH and to some extent by the NTS. In contrast, no additional benefit of the conjugate was noted on food reward when the compound was microinjected into the LH or the NTS, identifying the SUM as the only neural substrate identified here to underlie the reward reducing benefits of GLP-1 and estrogen conjugate. Collectively we discover a surprising neural substrate underlying food intake and reward effects of GLP-1 and estrogen and uncover a new brain area capable of regulating energy balance and reward. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  7. The glucagon-like peptide-1 receptor agonist liraglutide improves hypoxia-induced pulmonary hypertension in mice partly via normalization of reduced ET(B) receptor expression.

    PubMed

    Honda, J; Kimura, T; Sakai, S; Maruyama, H; Tajiri, K; Murakoshi, N; Homma, S; Miyauchi, T; Aonuma, K

    2018-06-27

    The glucagon-like peptide-1 receptor (GLP-1R) agonist liraglutide is an incretin hormone mimetic used in the treatment of diabetes. However, the effects of liraglutide on pulmonary hypertension (PH) and pulmonary endothelin (ET) system are unknown. Eight-week-old C57BL6/J mice were injected liraglutide or vehicle for 5 weeks. One week after injection, the mice were exposed to either room air (normoxia) or chronic hypoxia (10 % O(2)) for 4 weeks. The right ventricular systolic pressure (RVSP) was significantly higher in hypoxia + vehicle group than in normoxia + vehicle group. ET-1 mRNA expression in the lungs was comparable among all the groups. ET(B) mRNA and protein expression in the lungs was significantly lower in hypoxia + vehicle group than in normoxia + vehicle group. The above changes were normalized by liraglutide treatment. The expression of phospho-eNOS and phospho-AMPK proteins in the lungs was significantly higher in hypoxia + liraglutide group than in normoxia + vehicle group. We demonstrated for the first time that liraglutide effectively improved RVSP and RV hypertrophy in hypoxia-induced PH mice by activating eNOS through normalization of impaired ET(B) pathway and augmentation of AMPK pathway. Therefore, GLP-1R agonists can be promising therapeutic agents for PH.

  8. Effect of oral contraceptives and/or metformin on GLP-1 secretion and reactive hypoglycaemia in polycystic ovary syndrome.

    PubMed

    Glintborg, Dorte; Mumm, Hanne; Holst, Jens Juul; Andersen, Marianne

    2017-05-01

    Insulin resistance in polycystic ovary syndrome (PCOS) may increase the risk of reactive hypoglycaemia (RH) and decrease glucagon-like peptide-1 (GLP-1) secretion. The possible effects of treatment with oral contraceptives (OCP) and/or metformin on GLP-1 secretion and risk of RH in PCOS is undetermined. Outpatient clinic. Randomized, controlled clinical trial. Ninety women with PCOS were randomized to 12-month treatment with OCP (150 mg desogestrel + 30 mg ethinylestradiol), metformin (2 g/day) or metformin + OCP. Five-hour oral glucose tolerance tests (5-h OGTT) measuring fasting and area under the curve (AUC) for GLP-1, glucose, insulin and C-peptide were performed before and after the intervention period. Sixty-five women completed the study and 34 weight-matched healthy women were included as controls. Changes in GLP-1, glucose, insulin and C-peptide during 5-h OGTT. Fasting GLP-1 levels increased during metformin + OCP vs OCP treatment, whereas AUC GLP-1 levels were unchanged during medical treatment. The prevalence of reactive hypoglycemia increased from 9/65 to 14/65 after intervention ( P  < 0.01) and was more common after treatment with metformin + OCP (increase from 3/23 to 6/23, P  = 0.01). Reactive hypoglycaemia was associated with higher insulin and C-peptide levels during 5-h OGTT, but was unassociated with BMI and AUC GLP-1. GLP-1 levels were comparable in PCOS vs controls. AUC GLP-1 levels were significantly lower in obese vs lean patients and were inversely associated with BMI. AUC GLP-1 levels were unchanged during treatment. Increased risk of hypoglycemia during metformin + OCP could be associated with increased insulin secretion. © 2017 The authors.

  9. Exendin-4 and GLP-1 decreases induced expression of ICAM-1, VCAM-1 and RAGE in human retinal pigment epithelial cells.

    PubMed

    Dorecka, Mariola; Siemianowicz, Krzysztof; Francuz, Tomasz; Garczorz, Wojciech; Chyra, Agnieszka; Klych, Agnieszka; Romaniuk, Wanda

    2013-01-01

    Advanced glycation end products (AGEs) take part in the development of diabetic retinopathy. Hyperglycemia triggers an inflammatory response in the retina. These mechanisms may lead to an enhanced expression of adhesion molecules (ICAM-1 and VCAM-1) in human retinal pigment epithelium (HRPE). Glucagon-like peptide 1 (GLP-1) functions as an incretin hormone with antidiabetogenic properties. GLP-1 also possesses vasoprotective properties. The aim of our study was to evaluate the influence of glycated albumin (GlyAlb; 100; 500 and 1000 mg/l) and pro-inflammatory cytokine, TNF-α (2.5 and 10 ng/ml), on expression of RAGE, ICAM-1 and VCAM-1 and to evaluate the influence of GLP-1 (100 nM) and its analogue, exendin-4 (10 nM), on the expression of RAGE, ICAM-1 and VCAM-1 in stimulated HRPE. TNF-α increased RAGE expression in HRPE cells. The addition of GlyAlb (500 and 1000 mg/l) resulted in a decrease of RAGE expression. Both TNF-α and GlyAlb increased the secretion of both adhesion molecules. In cells co-treated with GLP-1 or exendin-4 both incretins decreased RAGE expression in TNF-α treated cells, and in GlyAlb group. The ICAM-1 expression was lowered by exendin-4 and GLP-1 in cells stimulated by TNF-α and GlyAlb. The similar results were obtained for VCAM-1. All observed alterations were statistically significant. The obtained results indicate that both GLP-1 and exendin-4 by decreasing the expression of RAGE in HRPE can make these cells more resistant to circulating AGEs, and decreased expression of circulating VCAM-1 and ICAM-1, can be the result of anti-inflammatory properties of incretins and decreased expression of RAGE.

  10. GLP-1 Receptor Agonists

    MedlinePlus

    ... Secretagogues TZDs Changing Your Lifestyle Diabetes Complications Nondiabetic Hypoglycemia Featured Resource Taming the Spikes Is mealtime insulin ... t cause low blood glucose, a condition called hypoglycemia. But you’re at risk for low blood ...

  11. Acting on Hormone Receptors with Minimal Side Effect on Cell Proliferation: A Timely Challenge Illustrated with GLP-1R and GPER.

    PubMed

    Gigoux, Véronique; Fourmy, Daniel

    2013-01-01

    G protein-coupled receptors (GPCRs) constitute a large family of receptors that sense molecules outside the cell and activate inside signal transduction pathways and cellular responses. GPCR are involved in a wide variety of physiological processes, including in the neuroendocrine system. GPCR are also involved in many diseases and are the target of 30% of marketed medicinal drugs. Whereas the majority of the GPCR-targeting drugs have proved their therapeutic benefit, some of them were associated with undesired effects. We develop two examples of used drugs whose therapeutic benefits are tarnished by carcinogenesis risks. The chronic administration of glucagon-like peptide-1 (GLP-1) analogs widely used to treat type-2 diabetes was associated with an increased risk of pancreatic or thyroid cancers. The long-term treatment with the estrogen antagonist tamoxifen, developed to target breast cancer overexpressing estrogen receptors ER, presents agonist activity on the G protein-coupled estrogen receptor which is associated with an increased incidence of endometrial cancer and breast cancer resistance to hormonotherapy. We point out and discuss the need of pharmacological studies to understand and overcome the undesired effects associated with the chronic administration of GPCR ligands. In fact, biological effects triggered by GPCR often result from the activation of multiple intracellular signaling pathways. Deciphering which signaling networks are engaged following GPCR activation appears to be primordial to unveil their contribution in the physiological and physiopathological processes. The development of biased agonists to elucidate the role of the different signaling mechanisms mediated by GPCR activation will allow the generation of new therapeutic agents with improved efficacy and reduced side effects. In this regard, the identification of GLP-1R biased ligands promoting insulin secretion without inducing pro-tumoral effects would offer therapeutic benefit.

  12. Induction of miR-132 and miR-212 Expression by Glucagon-Like Peptide 1 (GLP-1) in Rodent and Human Pancreatic β-Cells

    PubMed Central

    Li, Jing; Keller, Mark P.; Hohmeier, Hans E.; Wang, Yong; Feng, Yue; Zhou, Heather H.; Shen, Xiaolan; Rabaglia, Mary; Soni, Mufaddal; Attie, Alan D.; Newgard, Christopher B.; Thornberry, Nancy A.; Howard, Andrew D.; Zhou, Yun-Ping

    2015-01-01

    Better understanding how glucagon-like peptide 1 (GLP-1) promotes pancreatic β-cell function and/or mass may uncover new treatment for type 2 diabetes. In this study, we investigated the potential involvement of microRNAs (miRNAs) in the effect of GLP-1 on glucose-stimulated insulin secretion. miRNA levels in INS-1 cells and isolated rodent and human islets treated with GLP-1 in vitro and in vivo (with osmotic pumps) were measured by real-time quantitative PCR. The role of miRNAs on insulin secretion was studied by transfecting INS-1 cells with either precursors or antisense inhibitors of miRNAs. Among the 250 miRNAs surveyed, miR-132 and miR-212 were significantly up-regulated by GLP-1 by greater than 2-fold in INS-1 832/3 cells, which were subsequently reproduced in freshly isolated rat, mouse, and human islets, as well as the islets from GLP-1 infusion in vivo in mice. The inductions of miR-132 and miR-212 by GLP-1 were correlated with cAMP production and were blocked by the protein kinase A inhibitor H-89 but not affected by the exchange protein activated by cAMP activator 8-pCPT-2′-O-Me-cAMP-AM. GLP-1 failed to increase miR-132 or miR-212 expression levels in the 832/13 line of INS-1 cells, which lacks robust cAMP and insulin responses to GLP-1 treatment. Overexpression of miR-132 or miR-212 significantly enhanced glucose-stimulated insulin secretion in both 832/3 and 832/13 cells, and restored insulin responses to GLP-1 in INS-1 832/13 cells. GLP-1 increases the expression of miRNAs 132 and 212 via a cAMP/protein kinase A-dependent pathway in pancreatic β-cells. Overexpression of miR-132 or miR-212 enhances glucose and GLP-1-stimulated insulin secretion. PMID:26218441

  13. Induction of miR-132 and miR-212 Expression by Glucagon-Like Peptide 1 (GLP-1) in Rodent and Human Pancreatic β-Cells.

    PubMed

    Shang, Jin; Li, Jing; Keller, Mark P; Hohmeier, Hans E; Wang, Yong; Feng, Yue; Zhou, Heather H; Shen, Xiaolan; Rabaglia, Mary; Soni, Mufaddal; Attie, Alan D; Newgard, Christopher B; Thornberry, Nancy A; Howard, Andrew D; Zhou, Yun-Ping

    2015-09-01

    Better understanding how glucagon-like peptide 1 (GLP-1) promotes pancreatic β-cell function and/or mass may uncover new treatment for type 2 diabetes. In this study, we investigated the potential involvement of microRNAs (miRNAs) in the effect of GLP-1 on glucose-stimulated insulin secretion. miRNA levels in INS-1 cells and isolated rodent and human islets treated with GLP-1 in vitro and in vivo (with osmotic pumps) were measured by real-time quantitative PCR. The role of miRNAs on insulin secretion was studied by transfecting INS-1 cells with either precursors or antisense inhibitors of miRNAs. Among the 250 miRNAs surveyed, miR-132 and miR-212 were significantly up-regulated by GLP-1 by greater than 2-fold in INS-1 832/3 cells, which were subsequently reproduced in freshly isolated rat, mouse, and human islets, as well as the islets from GLP-1 infusion in vivo in mice. The inductions of miR-132 and miR-212 by GLP-1 were correlated with cAMP production and were blocked by the protein kinase A inhibitor H-89 but not affected by the exchange protein activated by cAMP activator 8-pCPT-2'-O-Me-cAMP-AM. GLP-1 failed to increase miR-132 or miR-212 expression levels in the 832/13 line of INS-1 cells, which lacks robust cAMP and insulin responses to GLP-1 treatment. Overexpression of miR-132 or miR-212 significantly enhanced glucose-stimulated insulin secretion in both 832/3 and 832/13 cells, and restored insulin responses to GLP-1 in INS-1 832/13 cells. GLP-1 increases the expression of miRNAs 132 and 212 via a cAMP/protein kinase A-dependent pathway in pancreatic β-cells. Overexpression of miR-132 or miR-212 enhances glucose and GLP-1-stimulated insulin secretion.

  14. Efficacy and Acceptability of Glycemic Control of Glucagon-Like Peptide-1 Receptor Agonists among Type 2 Diabetes: A Systematic Review and Network Meta-Analysis.

    PubMed

    Li, Zhixia; Zhang, Yuan; Quan, Xiaochi; Yang, Zhirong; Zeng, Xiantao; Ji, Linong; Sun, Feng; Zhan, Siyan

    2016-01-01

    To synthesize current evidence of the impact of Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) on hypoglycemia, treatment discontinuation and glycemic level in patients with type 2 diabetes. Systematic review and network meta-analysis. Literature search (Medline, Embase, the Cochrane library), website of clinical trial, bibliographies of published systematic reviews. Randomized controlled trials with available data comparing GLP-1 RAs with placebo or traditional anti-diabetic drugs in patients with type 2 diabetes. Traditional pairwise meta-analyses within DerSimonian-Laird random effects model and network meta-analysis within a Bayesian framework were performed to calculate odds ratios for the incidence of hypoglycemia, treatment discontinuation, HbA1c<7.0% and HbA1c<6.5%. Ranking probabilities for all treatments were estimated to obtain a treatment hierarchy using the surface under the cumulative ranking curve (SUCRA) and mean ranks. 78 trials with 13 treatments were included. Overall, all GLP-1 RAs except for albiglutide increased the risk of hypoglycemia when compared to placebo. Reduction in the incidence of hypoglycemia was found for all GLP-1 RAs versus insulin (except for dulaglutide) and sulphonylureas. For the incidence of treatment discontinuation, increase was found for exenatide, liraglutide, lixisenatide and taspoglutide versus placebo, insulin and sitagliptin. For glycemic level, decrease was found for all GLP-1 RAs versus placebo. Dulaglutide, exenatide long-acting release (exe_lar), liraglutide and taspoglutide had significant lowering effect when compared with sitagliptin (HbA1c<7.0%) and insulin (HbA1c<6.5%). Finally, according to SUCRAs, placebo, thiazolidinediones and albiglutide had the best decrease effect on hypoglycemia; sulphanylureas, sitagliptin and insulin decrease the incidence of treatment discontinuation most; exe_lar and dulaglutide had the highest impact on glycemic level among 13 treatments. Among 13 treatments, GLP-1 RAs

  15. Structural and Biochemical Characterization of the Type II Fructose-1,6-bisphosphatase GlpX from Escherichia coli

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brown, G.; Singer, A.; Lunin, V. V.

    2009-02-06

    Gluconeogenesis is an important metabolic pathway, which produces glucose from noncarbohydrate precursors such as organic acids, fatty acids, amino acids, or glycerol. Fructose-1,6-bisphosphatase, a key enzyme of gluconeogenesis, is found in all organisms, and five different classes of these enzymes have been identified. Here we demonstrate that Escherichia coli has two class II fructose-1,6-bisphosphatases, GlpX and YggF, which show different catalytic properties. We present the first crystal structure of a class II fructose-1,6-bisphosphatase (GlpX) determined in a free state and in the complex with a substrate (fructose 1,6-bisphosphate) or inhibitor (phosphate). The crystal structure of the ligand-free GlpX revealed amore » compact, globular shape with two {alpha}/{beta}-sandwich domains. The core fold of GlpX is structurally similar to that of Li{sup +}-sensitive phosphatases implying that they have a common evolutionary origin and catalytic mechanism. The structure of the GlpX complex with fructose 1,6-bisphosphate revealed that the active site is located between two domains and accommodates several conserved residues coordinating two metal ions and the substrate. The third metal ion is bound to phosphate 6 of the substrate. Inorganic phosphate strongly inhibited activity of both GlpX and YggF, and the crystal structure of the GlpX complex with phosphate demonstrated that the inhibitor molecule binds to the active site. Alanine replacement mutagenesis of GlpX identified 12 conserved residues important for activity and suggested that Thr{sup 90} is the primary catalytic residue. Our data provide insight into the molecular mechanisms of the substrate specificity and catalysis of GlpX and other class II fructose-1,6-bisphosphatases.« less

  16. Venous blood provides lower GLP-1 concentrations than arterialised blood in the postprandial, but not fasted state: Consequences of sampling methods.

    PubMed

    Chen, Yung-Chih; Edinburgh, Robert M; Hengist, Aaron; Smith, Harry A; Walhin, Jean-Philippe; Betts, James A; Thompson, Dylan; Gonzalez, Javier T

    2018-06-27

    What is the central question of this study? Glucagon-like peptide-1 (GLP-1) is an important obesity/diabetes target, with effects dependent on circulating GLP-1 concentrations. Peripheral tissues extract GLP-1, therefore sampling venous versus arterialised blood may provide different GLP-1 concentrations. This study examined whether arterialisation alters GLP-1 concentrations during fasting and feeding. What is the main finding and its importance? This study demonstrates that venous blood provides lower postprandial, but not fasting, GLP-1 concentrations versus arterialised blood. Therefore, when accurate assessment of postprandial peripheral availability of GLP-1 is required, blood sampling methods should be carefully considered, clearly reported, and arterialisation is recommended. Glucagon-like peptide-1 (GLP-1) displays concentration-dependent effects on metabolism, appetite and angiogenesis, so accurate determination of circulating GLP-1 concentrations is important. This study compared GLP-1 concentrations in venous versus arterialised blood under both fasted and fed conditions. Venous and arterialised blood samples were simultaneously drawn from ten, young, healthy men before, and 30, 60 and 120 min after, ingestion of 75 g glucose. Plasma GLP-1 concentrations increased in response to glucose ingestion (time effect: p < 0.01) and to a lesser extend in venous versus arterialised plasma (time x arterialisation interaction: p < 0.01). Accordingly, the plasma incremental area under the curve was lower in venous versus arterialised plasma (974 ± 88 versus 1214 ± 115 pmol·L x 120 min -1 , respectively, p = 0.049). In the postprandial state, there was a positive relationship between arterialised GLP-1 concentrations and the venous-arterialised difference in GLP-1 concentrations (r 2  = 0.51; p < 0.01). Both arterialised and venous peak GLP-1 concentrations showed positive relationships with peak arterialised insulin concentrations (both r 2

  17. Exenatide Regulates Cerebral Glucose Metabolism in Brain Areas Associated With Glucose Homeostasis and Reward System.

    PubMed

    Daniele, Giuseppe; Iozzo, Patricia; Molina-Carrion, Marjorie; Lancaster, Jack; Ciociaro, Demetrio; Cersosimo, Eugenio; Tripathy, Devjit; Triplitt, Curtis; Fox, Peter; Musi, Nicolas; DeFronzo, Ralph; Gastaldelli, Amalia

    2015-10-01

    Glucagon-like peptide 1 receptors (GLP-1Rs) have been found in the brain, but whether GLP-1R agonists (GLP-1RAs) influence brain glucose metabolism is currently unknown. The study aim was to evaluate the effects of a single injection of the GLP-1RA exenatide on cerebral and peripheral glucose metabolism in response to a glucose load. In 15 male subjects with HbA1c of 5.7 ± 0.1%, fasting glucose of 114 ± 3 mg/dL, and 2-h glucose of 177 ± 11 mg/dL, exenatide (5 μg) or placebo was injected in double-blind, randomized fashion subcutaneously 30 min before an oral glucose tolerance test (OGTT). The cerebral glucose metabolic rate (CMRglu) was measured by positron emission tomography after an injection of [(18)F]2-fluoro-2-deoxy-d-glucose before the OGTT, and the rate of glucose absorption (RaO) and disposal was assessed using stable isotope tracers. Exenatide reduced RaO0-60 min (4.6 ± 1.4 vs. 13.1 ± 1.7 μmol/min ⋅ kg) and decreased the rise in mean glucose0-60 min (107 ± 6 vs. 138 ± 8 mg/dL) and insulin0-60 min (17.3 ± 3.1 vs. 24.7 ± 3.8 mU/L). Exenatide increased CMRglu in areas of the brain related to glucose homeostasis, appetite, and food reward, despite lower plasma insulin concentrations, but reduced glucose uptake in the hypothalamus. Decreased RaO0-60 min after exenatide was inversely correlated to CMRglu. In conclusion, these results demonstrate, for the first time in man, a major effect of a GLP-1RA on regulation of brain glucose metabolism in the absorptive state. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  18. Activation of GLP-1 receptors on vascular smooth muscle cells reduces the autoregulatory response in afferent arterioles and increases renal blood flow.

    PubMed

    Jensen, Elisa P; Poulsen, Steen S; Kissow, Hannelouise; Holstein-Rathlou, Niels-Henrik; Deacon, Carolyn F; Jensen, Boye L; Holst, Jens J; Sorensen, Charlotte M

    2015-04-15

    Glucagon-like peptide (GLP)-1 has a range of extrapancreatic effects, including renal effects. The mechanisms are poorly understood, but GLP-1 receptors have been identified in the kidney. However, the exact cellular localization of the renal receptors is poorly described. The aim of the present study was to localize renal GLP-1 receptors and describe GLP-1-mediated effects on the renal vasculature. We hypothesized that renal GLP-1 receptors are located in the renal microcirculation and that activation of these affects renal autoregulation and increases renal blood flow. In vivo autoradiography using (125)I-labeled GLP-1, (125)I-labeled exendin-4 (GLP-1 analog), and (125)I-labeled exendin 9-39 (GLP-1 receptor antagonist) was performed in rodents to localize specific GLP-1 receptor binding. GLP-1-mediated effects on blood pressure, renal blood flow (RBF), heart rate, renin secretion, urinary flow rate, and Na(+) and K(+) excretion were investigated in anesthetized rats. Effects of GLP-1 on afferent arterioles were investigated in isolated mouse kidneys. Specific binding of (125)I-labeled GLP-1, (125)I-labeled exendin-4, and (125)I-labeled exendin 9-39 was observed in the renal vasculature, including afferent arterioles. Infusion of GLP-1 increased blood pressure, RBF, and urinary flow rate significantly in rats. Heart rate and plasma renin concentrations were unchanged. Exendin 9-39 inhibited the increase in RBF. In isolated murine kidneys, GLP-1 and exendin-4 significantly reduced the autoregulatory response of afferent arterioles in response to stepwise increases in pressure. We conclude that GLP-1 receptors are located in the renal vasculature, including afferent arterioles. Activation of these receptors reduces the autoregulatory response of afferent arterioles to acute pressure increases and increases RBF in normotensive rats. Copyright © 2015 the American Physiological Society.

  19. Changes in gut microbiota control inflammation in obese mice through a mechanism involving GLP-2-driven improvement of gut permeability.

    PubMed

    Cani, P D; Possemiers, S; Van de Wiele, T; Guiot, Y; Everard, A; Rottier, O; Geurts, L; Naslain, D; Neyrinck, A; Lambert, D M; Muccioli, G G; Delzenne, N M

    2009-08-01

    Obese and diabetic mice display enhanced intestinal permeability and metabolic endotoxaemia that participate in the occurrence of metabolic disorders. Our recent data support the idea that a selective increase of Bifidobacterium spp. reduces the impact of high-fat diet-induced metabolic endotoxaemia and inflammatory disorders. Here, we hypothesised that prebiotic modulation of gut microbiota lowers intestinal permeability, by a mechanism involving glucagon-like peptide-2 (GLP-2) thereby improving inflammation and metabolic disorders during obesity and diabetes. Study 1: ob/ob mice (Ob-CT) were treated with either prebiotic (Ob-Pre) or non-prebiotic carbohydrates as control (Ob-Cell). Study 2: Ob-CT and Ob-Pre mice were treated with GLP-2 antagonist or saline. Study 3: Ob-CT mice were treated with a GLP-2 agonist or saline. We assessed changes in the gut microbiota, intestinal permeability, gut peptides, intestinal epithelial tight-junction proteins ZO-1 and occludin (qPCR and immunohistochemistry), hepatic and systemic inflammation. Prebiotic-treated mice exhibited a lower plasma lipopolysaccharide (LPS) and cytokines, and a decreased hepatic expression of inflammatory and oxidative stress markers. This decreased inflammatory tone was associated with a lower intestinal permeability and improved tight-junction integrity compared to controls. Prebiotic increased the endogenous intestinotrophic proglucagon-derived peptide (GLP-2) production whereas the GLP-2 antagonist abolished most of the prebiotic effects. Finally, pharmacological GLP-2 treatment decreased gut permeability, systemic and hepatic inflammatory phenotype associated with obesity to a similar extent as that observed following prebiotic-induced changes in gut microbiota. We found that a selective gut microbiota change controls and increases endogenous GLP-2 production, and consequently improves gut barrier functions by a GLP-2-dependent mechanism, contributing to the improvement of gut barrier functions

  20. Dietary resistant starch upregulates total GLP-1 and PYY in a sustained day-long manner through fermentation in rodents.

    PubMed

    Zhou, June; Martin, Roy J; Tulley, Richard T; Raggio, Anne M; McCutcheon, Kathleen L; Shen, Li; Danna, Samuel Colby; Tripathy, Sasmita; Hegsted, Maren; Keenan, Michael J

    2008-11-01

    Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) are anti-diabetes/obesity hormones secreted from the gut after meal ingestion. We have shown that dietary-resistant starch (RS) increased GLP-1 and PYY secretion, but the mechanism remains unknown. RS is a fermentable fiber that lowers the glycemic index of the diet and liberates short-chain fatty acids (SCFAs) through fermentation in the gut. This study investigates the two possible mechanisms by which RS stimulates GLP-1 and PYY secretion: the effect of a meal or glycemic index, and the effect of fermentation. Because GLP-1 and PYY secretions are stimulated by nutrient availability in the gut, the timing of blood sample collections could influence the outcome when two diets with different glycemic indexes are compared. Thus we examined GLP-1 and PYY plasma levels at various time points over a 24-h period in RS-fed rats. In addition, we tested proglucagon (a precursor to GLP-1) and PYY gene expression patterns in specific areas of the gut of RS-fed rats and in an enteroendocrine cell line following exposure to SCFAs in vitro. Our findings are as follows. 1) RS stimulates GLP-1 and PYY secretion in a substantial day-long manner, independent of meal effect or changes in dietary glycemia. 2) Fermentation and the liberation of SCFAs in the lower gut are associated with increased proglucagon and PYY gene expression. 3) Glucose tolerance, an indicator of increased active forms of GLP-1 and PYY, was improved in RS-fed diabetic mice. We conclude that fermentation of RS is most likely the primary mechanism for increased endogenous secretions of total GLP-1 and PYY in rodents. Thus any factor that affects fermentation should be considered when dietary fermentable fiber is used to stimulate GLP-1 and PYY secretion.

  1. Novel role of GLP-1 receptor signaling in energy expenditure during chronic high fat diet feeding in rats.

    PubMed

    Krieger, Jean-Philippe; Langhans, Wolfgang; Lee, Shin J

    2018-04-11

    Glucagon-like peptide-1 (GLP-1) secreted from intestinal L-cells plays a major role in meal termination and glucose-dependent insulin secretion. Several lines of evidence indicate, however, that the acute satiating and incretin effects of GLP-1 are attenuated with high fat diet (HFD) exposure. Here we tested the hypothesis that endogenous GLP-1 differentially affects energy balance and glucose homeostasis dependent on whether rats are fed chow or HFD (60% energy from fat). We blocked GLP-1 receptor (GLP-1R) signaling by daily intraperitoneal (IP) injection of the GLP-1R antagonist exendin (9-39) (Ex9, 10 μg/kg) or vehicle for 5 weeks in male Sprague-Dawley rats fed either chow or HFD, recorded body weight (BW) and food intake throughout, and assessed energy expenditure (3rd week) and glucose tolerance (4th week). Five week daily Ex9 injections reduced BW gain in HFD-fed rats, but did not affect BW in chow-fed rats. On the other hand, chronic Ex9 treatment did not affect daily food intake in either chow or HFD-fed rats during the entire study. The reduced BW gain in HFD-fed rats was associated with an increase in energy expenditure. Interestingly, chronic Ex9 treatment induced glucose intolerance in chow-fed rats, but not in HFD-fed rats, suggesting a differential role of GLP-1R signaling in glucose metabolism during chow and HFD feeding. Our findings reveal a novel role of GLP-1R signaling, modulating energy expenditure rather than eating behavior during HFD feeding. Furthermore, these results suggest a previously unrecognized contribution of GLP-1R signaling to the pathophysiology of obesity. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. The interleukin (IL)-1 cytokine family--Balance between agonists and antagonists in inflammatory diseases.

    PubMed

    Palomo, Jennifer; Dietrich, Damien; Martin, Praxedis; Palmer, Gaby; Gabay, Cem

    2015-11-01

    The interleukin (IL)-1 family of cytokines comprises 11 members, including 7 pro-inflammatory agonists (IL-1α, IL-1β, IL-18, IL-33, IL-36α, IL-36β, IL-36γ) and 4 defined or putative antagonists (IL-1R antagonist (IL-1Ra), IL-36Ra, IL-37, and IL-38) exerting anti-inflammatory activities. Except for IL-1Ra, IL-1 cytokines do not possess a leader sequence and are secreted via an unconventional pathway. In addition, IL-1β and IL-18 are produced as biologically inert pro-peptides that require cleavage by caspase-1 in their N-terminal region to generate active proteins. N-terminal processing is also required for full activity of IL-36 cytokines. The IL-1 receptor (IL-1R) family comprises 10 members and includes cytokine-specific receptors, co-receptors and inhibitory receptors. The signaling IL-1Rs share a common structure with three extracellular immunoglobulin (Ig) domains and an intracellular Toll-like/IL-1R (TIR) domain. IL-1 cytokines bind to their specific receptor, which leads to the recruitment of a co-receptor and intracellular signaling. IL-1 cytokines induce potent inflammatory responses and their activity is tightly controlled at the level of production, protein processing and maturation, receptor binding and post-receptor signaling by naturally occurring inhibitors. Some of these inhibitors are IL-1 family antagonists, while others are IL-1R family members acting as membrane-bound or soluble decoy receptors. An imbalance between agonist and antagonist levels can lead to exaggerated inflammatory responses. Several genetic modifications or mutations associated with dysregulated IL-1 activity and autoinflammatory disorders were identified in mouse models and in patients. These findings paved the road to the successful use of IL-1 inhibitors in diseases that were previously considered as untreatable. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Incretin Receptor Null Mice Reveal Key Role of GLP-1 but Not GIP in Pancreatic Beta Cell Adaptation to Pregnancy

    PubMed Central

    Moffett, R. Charlotte; Vasu, Srividya; Thorens, Bernard; Drucker, Daniel J.; Flatt, Peter R.

    2014-01-01

    Islet adaptations to pregnancy were explored in C57BL6/J mice lacking functional receptors for glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP). Pregnant wild type mice and GIPRKO mice exhibited marked increases in islet and beta cell area, numbers of medium/large sized islets, with positive effects on Ki67/Tunel ratio favouring beta cell growth and enhanced pancreatic insulin content. Alpha cell area and glucagon content were unchanged but prohormone convertases PC2 and PC1/3 together with significant amounts of GLP-1 and GIP were detected in alpha cells. Knockout of GLP-1R abolished these islet adaptations and paradoxically decreased pancreatic insulin, GLP-1 and GIP. This was associated with abolition of normal pregnancy-induced increases in plasma GIP, L-cell numbers, and intestinal GIP and GLP-1 stores. These data indicate that GLP-1 but not GIP is a key mediator of beta cell mass expansion and related adaptations in pregnancy, triggered in part by generation of intra-islet GLP-1. PMID:24927416

  4. Novel coumarin modified GLP-1 derivatives with enhanced plasma stability and prolonged in vivo glucose-lowering ability.

    PubMed

    Han, Jing; Sun, Lidan; Huang, Xun; Li, Zheng; Zhang, Chenyu; Qian, Hai; Huang, Wenlong

    2014-12-01

    The short biological half-life limits the therapeutic use of glucagon-like peptide-1 (GLP-1) and chemical modification to improve the interaction of peptides with serum albumin represents an effective strategy to develop long-acting peptide analogues. Coumarin, a natural product, is known to bind tightly to plasma proteins and possesses many biological activities. Therefore, we designed and synthesized a series of coumarin-modified GLP-1 derivatives, hypothesizing that conjugation with coumarin would retain the therapeutic effects and prolong the biological half-life of the conjugates. Four cysteine-modified GLP-1 analogues (1-4) were prepared using Gly8 -GLP-1(7-36)-NH2 peptide as a starting point. These analogues were conjugated with two coumarin maleimides to yield eight compounds (conjugates 6-13) for testing. Activation of human GLP-1 receptors, stability to enzymic inactivation in plasma and binding to human albumin were assessed in vitro. In vivo, effects on oral glucose tolerance tests (OGTT) in rats and on blood glucose levels in db/db mice were studied. Most conjugates showed well preserved receptor activation efficacy, enhanced albumin-binding properties and improved in vitro plasma stability and conjugate 7 was selected to undergo further assessment. In rats, conjugate 7 had a longer circulating t1/2 than exendin-4 or liraglutide. A prolonged antidiabetic effect of conjugate 7 was observed after OGTT in rats and a prolonged hypoglycaemic effect in db/db mice. Cysteine-specific coumarin conjugation with GLP-1 offers a useful approach to the development of long-acting incretin-based antidiabetic agents. Conjugate 7 is a promising long-lasting GLP-1 derivative deserving further investigation. © 2014 The British Pharmacological Society.

  5. GLP-1 response to a mixed meal: what happens 10 years after Roux-en-Y gastric bypass (RYGB)?

    PubMed

    Dar, Moahad S; Chapman, William H; Pender, John R; Drake, Almond J; O'Brien, Kevin; Tanenberg, Robert J; Dohm, G Lynis; Pories, Walter J

    2012-07-01

    Oral meal consumption increases glucagon-like peptide 1 (GLP-1) release which maintains euglycemia by increasing insulin secretion. This effect is exaggerated during short-term follow-up of Roux-en-y gastric bypass (RYGB). We examined the durability of this effect in patient with type 2 diabetes (T2DM) >10 years after RYGB. GLP-1 response to a mixed meal in the 10-year post-RYGB group (n = 5) was compared to lean (n = 9), obese (n = 6), and type 2 diabetic (n = 10) controls using a cross-sectional study design. Analysis of variance (ANOVA) was used to evaluate GLP-1 response to mixed meal consumption from 0 to 300 min, 0-20 min, 20-60 min, and 60-300 min, respectively. Weight, insulin resistance, and T2DM were also assessed. GLP-1 response 0-300 min in the 10-year post-RYGB showed a statistically significant overall difference (p =  0.01) compared to controls. Furthermore, GLP-1 response 0-20 min in the 10-year post-RYGB group showed a very rapid statistically significant rise (p = 0.035) to a peak of 40 pM. GLP-1 response between 20 and 60 min showed a rapid statistically significant (p = 0.041) decline in GLP-1 response from ~40 pM to 10 pM. GLP-1 response in the 10-year post-RYGB group from 60 to 300 min showed no statistically significant difference from controls. BMI, HOMA, and fasting serum glucose before and >10 years after RYGB changed from 59.9 → 40.4, 8.7 → 0.88, and 155.2 → 87.6 mg/dl, respectively, and were statistically significant (p < 0.05). An exaggerated GLP-1 response was noted 10 years after RYGB, strongly suggesting a durability of this effect. This phenomenon may play a key role in maintaining type 2 diabetes remission and weight loss after RYGB.

  6. Activation of the GLP-1 receptors in the nucleus of the solitary tract reduces food reward behavior and targets the mesolimbic system.

    PubMed

    Richard, Jennifer E; Anderberg, Rozita H; Göteson, Andreas; Gribble, Fiona M; Reimann, Frank; Skibicka, Karolina P

    2015-01-01

    The gut/brain peptide, glucagon like peptide 1 (GLP-1), suppresses food intake by acting on receptors located in key energy balance regulating CNS areas, the hypothalamus or the hindbrain. Moreover, GLP-1 can reduce reward derived from food and motivation to obtain food by acting on its mesolimbic receptors. Together these data suggest a neuroanatomical segregation between homeostatic and reward effects of GLP-1. Here we aim to challenge this view and hypothesize that GLP-1 can regulate food reward behavior by acting directly on the hindbrain, the nucleus of the solitary tract (NTS), GLP-1 receptors (GLP-1R). Using two models of food reward, sucrose progressive ratio operant conditioning and conditioned place preference for food in rats, we show that intra-NTS microinjections of GLP-1 or Exendin-4, a stable analogue of GLP-1, inhibit food reward behavior. When the rats were given a choice between palatable food and chow, intra-NTS Exendin-4 treatment preferentially reduced intake of palatable food but not chow. However, chow intake and body weight were reduced by the NTS GLP-1R activation if chow was offered alone. The NTS GLP-1 activation did not alter general locomotor activity and did not induce nausea, measured by PICA. We further show that GLP-1 fibers are in close apposition to the NTS noradrenergic neurons, which were previously shown to provide a monosynaptic connection between the NTS and the mesolimbic system. Central GLP-1R activation also increased NTS expression of dopamine-β-hydroxylase, a key enzyme in noradrenaline synthesis, indicating a biological link between these two systems. Moreover, NTS GLP-1R activation altered the expression of dopamine-related genes in the ventral tegmental area. These data reveal a food reward-suppressing role of the NTS GLP-1R and indicate that the neurobiological targets underlying food reward control are not limited to the mesolimbic system, instead they are distributed throughout the CNS.

  7. Intraportal infusion of ghrelin could inhibit glucose-stimulated GLP-1 secretion by enteric neural net in Wistar rat.

    PubMed

    Zhang, Xiyao; Li, Wensong; Li, Ping; Chang, Manli; Huang, Xu; Li, Qiang; Cui, Can

    2014-01-01

    As a regulator of food intake and energy metabolism, the role of ghrelin in glucose metabolism is still not fully understood. In this study, we determined the in vivo effect of ghrelin on incretin effect. We demonstrated that ghrelin inhibited the glucose-stimulated release of glucagon-like peptide-1 (GLP-1) when infused into the portal vein of Wistar rat. Hepatic vagotomy diminished the inhibitory effect of ghrelin on glucose-stimulated GLP-1 secretion. In addition, phentolamine, a nonselective α receptor antagonist, could recover the decrease of GLP-1 release induced by ghrelin infusion. Pralmorelin (an artificial growth hormone release peptide) infusion into the portal vein could also inhibit the glucose-stimulated release of GLP-1. And growth hormone secretagogue receptor antagonist, [D-lys3]-GHRP-6, infusion showed comparable increases of glucose stimulated GLP-1 release compared to ghrelin infusion into the portal vein. The data showed that intraportal infusion of ghrelin exerted an inhibitory effect on GLP-1 secretion through growth hormone secretagogue receptor 1α (GHS1α receptor), which indicated that the downregulation of ghrelin secretion after food intake was necessary for incretin effect. Furthermore, our results suggested that the enteric neural net involved hepatic vagal nerve and sympathetic nerve mediated inhibition effect of ghrelin on incretin effect.

  8. The GLP-1 response to glucose does not mediate beta and alpha cell dysfunction in Hispanics with abnormal glucose metabolism.

    PubMed

    Adams, Elizabeth; Genter, Pauline; Keefe, Emma; Sandow, Kevin; Gray, Virginia; Rotter, Jerome I; Chen, Yii-Der Ida; Ipp, Eli

    2018-01-01

    Glucagon-like peptide-1 (GLP-1) contributes to insulin secretion after meals. Though Hispanics have increased risk for type 2 diabetes mellitus, it is unknown if impaired GLP-1 secretion contributes to this risk. We therefore studied plasma GLP-1 secretion and action in Hispanic adults. Hispanic (H; n = 31) and non-Hispanic (nH; n = 15) participants underwent an oral glucose tolerance test (OGTT). All participants were categorized by glucose tolerance into four groups: normal glucose tolerant non-Hispanic (NGT-nH; n = 15), normal glucose tolerant Hispanic (NGT-H; n = 12), impaired glucose tolerant Hispanic (IGT-H; n = 11), or newly diagnosed type 2 diabetes mellitus, Hispanic (T2D-H; n = 8). Glucose-induced increments in plasma GLP-1 (Δ-GLP-1) were not different in NGT-H and NGT-nH (p = .38), nor amongst Hispanic subgroups with varying degrees of glucose homeostasis (p = .6). In contrast, the insulinogenic index in T2D-H group was lower than the other groups (p = .016). Subjects with abnormal glucose homeostasis (AGH), i.e., T2D-H plus IGT-H, had a diminished glucagon suppression index compared to patients with normal glucose homeostasis (NGT-H plus NGT-nH) (p = .035). GLP-1 responses to glucose were similar in Hispanic and Non-Hispanic NGT. Despite similar glucose-induced Δ-GLP-1, insulin and glucagon responses were abnormal in T2D-H and AGH, respectively. Thus, impaired GLP-1 secretion is unlikely to play a role in islet dysfunction in T2D. Although GLP-1 therapeutics enhance insulin secretion and glucagon suppression, it is likely due to pharmacological amplification of the GLP-1 pathways rather than treatment of hormonal deficiency. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Truncated Glucagon-like Peptide-1 and Exendin-4 α-Conotoxin pl14a Peptide Chimeras Maintain Potency and α-Helicity and Reveal Interactions Vital for cAMP Signaling in Vitro*

    PubMed Central

    Swedberg, Joakim E.; Schroeder, Christina I.; Mitchell, Justin M.; Fairlie, David P.; Edmonds, David J.; Griffith, David A.; Ruggeri, Roger B.; Derksen, David R.; Loria, Paula M.; Price, David A.; Liras, Spiros; Craik, David J.

    2016-01-01

    Glucagon-like peptide-1 (GLP-1) signaling through the glucagon-like peptide 1 receptor (GLP-1R) is a key regulator of normal glucose metabolism, and exogenous GLP-1R agonist therapy is a promising avenue for the treatment of type 2 diabetes mellitus. To date, the development of therapeutic GLP-1R agonists has focused on producing drugs with an extended serum half-life. This has been achieved by engineering synthetic analogs of GLP-1 or the more stable exogenous GLP-1R agonist exendin-4 (Ex-4). These synthetic peptide hormones share the overall structure of GLP-1 and Ex-4, with a C-terminal helical segment and a flexible N-terminal tail. Although numerous studies have investigated the molecular determinants underpinning GLP-1 and Ex-4 binding and signaling through the GLP-1R, these have primarily focused on the length and composition of the N-terminal tail or on how to modulate the helicity of the full-length peptides. Here, we investigate the effect of C-terminal truncation in GLP-1 and Ex-4 on the cAMP pathway. To ensure helical C-terminal regions in the truncated peptides, we produced a series of chimeric peptides combining the N-terminal portion of GLP-1 or Ex-4 and the C-terminal segment of the helix-promoting peptide α-conotoxin pl14a. The helicity and structures of the chimeric peptides were confirmed using circular dichroism and NMR, respectively. We found no direct correlation between the fractional helicity and potency in signaling via the cAMP pathway. Rather, the most important feature for efficient receptor binding and signaling was the C-terminal helical segment (residues 22–27) directing the binding of Phe22 into a hydrophobic pocket on the GLP-1R. PMID:27226591

  10. Novel coumarin modified GLP-1 derivatives with enhanced plasma stability and prolonged in vivo glucose-lowering ability

    PubMed Central

    Han, Jing; Sun, Lidan; Huang, Xun; Li, Zheng; Zhang, Chenyu; Qian, Hai; Huang, Wenlong

    2014-01-01

    Background and Purpose The short biological half-life limits the therapeutic use of glucagon-like peptide-1 (GLP-1) and chemical modification to improve the interaction of peptides with serum albumin represents an effective strategy to develop long-acting peptide analogues. Coumarin, a natural product, is known to bind tightly to plasma proteins and possesses many biological activities. Therefore, we designed and synthesized a series of coumarin-modified GLP-1 derivatives, hypothesizing that conjugation with coumarin would retain the therapeutic effects and prolong the biological half-life of the conjugates. Experimental Approach Four cysteine-modified GLP-1 analogues (1–4) were prepared using Gly8-GLP-1(7–36)-NH2 peptide as a starting point. These analogues were conjugated with two coumarin maleimides to yield eight compounds (conjugates 6–13) for testing. Activation of human GLP-1 receptors, stability to enzymic inactivation in plasma and binding to human albumin were assessed in vitro. In vivo, effects on oral glucose tolerance tests (OGTT) in rats and on blood glucose levels in db/db mice were studied. Key Results Most conjugates showed well preserved receptor activation efficacy, enhanced albumin-binding properties and improved in vitro plasma stability and conjugate 7 was selected to undergo further assessment. In rats, conjugate 7 had a longer circulating t1/2 than exendin-4 or liraglutide. A prolonged antidiabetic effect of conjugate 7 was observed after OGTT in rats and a prolonged hypoglycaemic effect in db/db mice. Conclusions and Implications Cysteine-specific coumarin conjugation with GLP-1 offers a useful approach to the development of long-acting incretin-based antidiabetic agents. Conjugate 7 is a promising long-lasting GLP-1 derivative deserving further investigation. PMID:25039358

  11. GLP-1 secretion is increased by inflammatory stimuli in an IL-6-dependent manner, leading to hyperinsulinemia and blood glucose lowering.

    PubMed

    Kahles, Florian; Meyer, Christina; Möllmann, Julia; Diebold, Sebastian; Findeisen, Hannes M; Lebherz, Corinna; Trautwein, Christian; Koch, Alexander; Tacke, Frank; Marx, Nikolaus; Lehrke, Michael

    2014-10-01

    Hypoglycemia and hyperglycemia are both predictors for adverse outcome in critically ill patients. Hyperinsulinemia is induced by inflammatory stimuli as a relevant mechanism for glucose lowering in the critically ill. The incretine hormone GLP-1 was currently found to be induced by endotoxin, leading to insulin secretion and glucose lowering under inflammatory conditions in mice. Here, we describe GLP-1 secretion to be increased by a variety of inflammatory stimuli, including endotoxin, interleukin-1β (IL-1β), and IL-6. Although abrogation of IL-1 signaling proved insufficient to prevent endotoxin-dependent GLP-1 induction, this was abolished in the absence of IL-6 in respective knockout animals. Hence, we found endotoxin-dependent GLP-1 secretion to be mediated by an inflammatory cascade, with IL-6 being necessary and sufficient for GLP-1 induction. Functionally, augmentation of the GLP-1 system by pharmacological inhibition of DPP-4 caused hyperinsulinemia, suppression of glucagon release, and glucose lowering under endotoxic conditions, whereas inhibition of the GLP-1 receptor led to the opposite effect. Furthermore, total GLP-1 plasma levels were profoundly increased in 155 critically ill patients presenting to the intensive care unit (ICU) in comparison with 134 healthy control subjects. In the ICU cohort, GLP-1 plasma levels correlated with markers of inflammation and disease severity. Consequently, GLP-1 provides a novel link between the immune system and the gut with strong relevance for metabolic regulation in context of inflammation. © 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  12. A novel human-based receptor antagonist of sustained action reveals body weight control by endogenous GLP-1.

    PubMed

    Patterson, James T; Ottaway, Nickki; Gelfanov, Vasily M; Smiley, David L; Perez-Tilve, Diego; Pfluger, Paul T; Tschöp, Matthias H; Dimarchi, Richard D

    2011-02-18

    Ex-4 (9-39)a is a well characterized GLP-1 receptor antagonist that suffers from two notable limitations, its nonhuman amino acid sequence and its relatively short in vivo duration of action. Comparable N-terminal shortening of human GLP-1 lessens agonism but does not provide a high potency antagonist. Through a series of GLP-1/Ex-4 hybrid peptides, the minimal structural changes required to generate a pure GLP-1-based antagonist were identified as Glu16, Val19, and Arg20, yielding an antagonist of approximately 3-fold greater in vitro potency compared with Ex-4 (9-39)a. The structural basis of antagonism appears to result from stabilization of the α helix combined with enhanced electrostatic and hydrophobic interactions with the extracellular domain of the receptor. Site-specific acylation of the human-based antagonist yielded a peptide of increased potency as a GLP-1 receptor antagonist and 10-fold greater selectivity relative to the GIP receptor. The acylated antagonist demonstrated sufficient duration of action to maintain inhibitory activity when administered as a daily subcutaneous injection. The sustained pharmacokinetics and enhanced human sequence combine to form an antagonist optimized for clinical study. Daily administration of this antagonist by subcutaneous injection to diet-induced obese mice for 1 week caused a significant increase in food intake, body weight, and glucose intolerance, demonstrating endogenous GLP-1 as a relevant hormone in mammalian energy balance in the obese state.

  13. SGLT2 inhibitors or GLP-1 receptor agonists as second-line therapy in type 2 diabetes: patient selection and perspectives.

    PubMed

    Gurgle, Holly E; White, Karen; McAdam-Marx, Carrie

    2016-01-01

    Controversy exists regarding the selection of second-line therapy for patients with type 2 diabetes mellitus (T2DM) who are unable to achieve glycemic control with metformin therapy alone. Newer pharmacologic treatments for T2DM include glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors. Both the classes of medication are efficacious, exhibit positive effects on weight, and are associated with minimal risk of hypoglycemia. The purpose of this review is to compare the clinical trial and real-world effectiveness data of glucagon-like peptide-1 receptor agonists versus sodium-glucose cotransporter 2 inhibitors related to A1c reduction, weight loss, cost-effectiveness, cardiovascular outcomes, and safety in patients with T2DM. This review summarizes comparative evidence for providers who are determining which of the two classes may be the most appropriate for a specific patient.

  14. PPG neurons of the lower brain stem and their role in brain GLP-1 receptor activation

    PubMed Central

    Cork, Simon C.

    2015-01-01

    Within the brain, glucagon-like peptide-1 (GLP-1) affects central autonomic neurons, including those controlling the cardiovascular system, thermogenesis, and energy balance. Additionally, GLP-1 influences the mesolimbic reward system to modulate the rewarding properties of palatable food. GLP-1 is produced in the gut and by hindbrain preproglucagon (PPG) neurons, located mainly in the nucleus tractus solitarii (NTS) and medullary intermediate reticular nucleus. Transgenic mice expressing glucagon promoter-driven yellow fluorescent protein revealed that PPG neurons not only project to central autonomic control regions and mesolimbic reward centers, but also strongly innervate spinal autonomic neurons. Therefore, these brain stem PPG neurons could directly modulate sympathetic outflow through their spinal inputs to sympathetic preganglionic neurons. Electrical recordings from PPG neurons in vitro have revealed that they receive synaptic inputs from vagal afferents entering via the solitary tract. Vagal afferents convey satiation to the brain from signals like postprandial gastric distention or activation of peripheral GLP-1 receptors. CCK and leptin, short- and long-term satiety peptides, respectively, increased the electrical activity of PPG neurons, while ghrelin, an orexigenic peptide, had no effect. These findings indicate that satiation is a main driver of PPG neuronal activation. They also show that PPG neurons are in a prime position to respond to both immediate and long-term indicators of energy and feeding status, enabling regulation of both energy balance and general autonomic homeostasis. This review discusses the question of whether PPG neurons, rather than gut-derived GLP-1, are providing the physiological substrate for the effects elicited by central nervous system GLP-1 receptor activation. PMID:26290108

  15. PPG neurons of the lower brain stem and their role in brain GLP-1 receptor activation.

    PubMed

    Trapp, Stefan; Cork, Simon C

    2015-10-15

    Within the brain, glucagon-like peptide-1 (GLP-1) affects central autonomic neurons, including those controlling the cardiovascular system, thermogenesis, and energy balance. Additionally, GLP-1 influences the mesolimbic reward system to modulate the rewarding properties of palatable food. GLP-1 is produced in the gut and by hindbrain preproglucagon (PPG) neurons, located mainly in the nucleus tractus solitarii (NTS) and medullary intermediate reticular nucleus. Transgenic mice expressing glucagon promoter-driven yellow fluorescent protein revealed that PPG neurons not only project to central autonomic control regions and mesolimbic reward centers, but also strongly innervate spinal autonomic neurons. Therefore, these brain stem PPG neurons could directly modulate sympathetic outflow through their spinal inputs to sympathetic preganglionic neurons. Electrical recordings from PPG neurons in vitro have revealed that they receive synaptic inputs from vagal afferents entering via the solitary tract. Vagal afferents convey satiation to the brain from signals like postprandial gastric distention or activation of peripheral GLP-1 receptors. CCK and leptin, short- and long-term satiety peptides, respectively, increased the electrical activity of PPG neurons, while ghrelin, an orexigenic peptide, had no effect. These findings indicate that satiation is a main driver of PPG neuronal activation. They also show that PPG neurons are in a prime position to respond to both immediate and long-term indicators of energy and feeding status, enabling regulation of both energy balance and general autonomic homeostasis. This review discusses the question of whether PPG neurons, rather than gut-derived GLP-1, are providing the physiological substrate for the effects elicited by central nervous system GLP-1 receptor activation. Copyright © 2015 the American Physiological Society.

  16. Presence and dynamics of leptin, GLP-1, and PYY in human breast milk at early postpartum.

    PubMed

    Schueler, Jessica; Alexander, Brenda; Hart, Ann Marie; Austin, Kathleen; Larson-Meyer, D Enette

    2013-07-01

    The presence of appetite hormones, namely glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and leptin in breast milk may be important in infant feeding regulation and infant growth. This study evaluated whether concentrations of GLP-1, PYY, and leptin change across a single feeding (from fore- to hindmilk), and are associated with maternal and infant anthropometrics. Thirteen postpartum women (mean ± SD: 25.6 ± 4.5 years, 72.0 ± 11.9 kg) provided fore- and hindmilk samples 4-5 weeks after delivery and underwent measurements of body weight and composition by Dual X-ray Absorptiometry. GLP-1, PYY, and leptin concentrations were measured using radioimmunoassay, and milk fat content was determined by creamatocrit. Concentration of GLP-1 and content of milk fat was higher in hindmilk than foremilk (P ≤ 0.05). PYY and leptin concentrations did not change between fore- and hindmilk. Both leptin concentration and milk fat content were correlated with indices of maternal adiposity, including body mass index (r = 0.65-0.85, P < 0.02), and fat mass (r = 0.65-0.84, P < 0.02). Hindmilk GLP-1 was correlated with infant weight gain from birth to 6 months (r = -0.67, P = 0.034). The presence of appetite hormones in breast milk may be important in infant appetite and growth regulation. Copyright © 2013 The Obesity Society.

  17. Acute peripheral administration of synthetic human GLP-1 (7-36 amide) decreases circulating IL-6 in obese patients with type 2 diabetes mellitus: a potential role for GLP-1 in modulation of the diabetic pro-inflammatory state?

    PubMed

    Daousi, Christina; Pinkney, Jonathan H; Cleator, Jacqueline; Wilding, John P; Ranganath, L R

    2013-05-10

    To explore the effects of acute administration of GLP-1 and GIP on circulating levels of key adipocyte-derived hormones and gut-brain peptides with established roles in energy and appetite regulation, modulation of insulin sensitivity and inflammation. Six obese male patients with diet-treated type 2 diabetes (T2DM) and 6 healthy lean subjects were studied. The protocol included 4 experiments for each participant that were carried out in randomised order and comprised: GLP-1 infusion at a rate of 1 pmol/kg/min for 4h, GIP at a rate of 2 pmol/kg/min, GLP-1+GIP and placebo infusion. Plasma leptin, adiponectin, IL-6, insulin, ghrelin and obestatin were measured at baseline, 15, 60, 120, 180 and 240 min following the start of infusion. Patients with T2DM had higher baseline IL-6 compared with healthy [day of placebo infusion: T2DM IL-6 mean (SEM) 1.3 (0.3) pg/ml vs 0.3 (0.1)pg/ml, p=0.003]. GLP-1 infusion in T2DM was associated with a significant reduction in circulating IL-6 [baseline IL-6 1.2 pg/ml vs IL-6=0.7 at 120 min, p=0.0001; vs IL-6=0.8 at 180 min, p=0.001]. There was no significant change in leptin, adiponectin, ghrelin or obestatin compared to baseline on all 4 experimental days in both groups. Short-term infusion of supraphysiological concentrations of GLP-1 in T2DM results in suppression of IL-6, a key inflammatory mediator strongly linked to development of obesity and T2DM-related insulin resistance. It remains to be confirmed whether GLP-1-based diabetes therapies can impact favourably on cardiovascular outcomes. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Glucagon-Like Peptide-1 Receptor Ligand Interactions: Structural Cross Talk between Ligands and the Extracellular Domain

    PubMed Central

    West, Graham M.; Willard, Francis S.; Sloop, Kyle W.; Showalter, Aaron D.; Pascal, Bruce D.; Griffin, Patrick R.

    2014-01-01

    Activation of the glucagon-like peptide-1 receptor (GLP-1R) in pancreatic β-cells potentiates insulin production and is a current therapeutic target for the treatment of type 2 diabetes mellitus (T2DM). Like other class B G protein-coupled receptors (GPCRs), the GLP-1R contains an N-terminal extracellular ligand binding domain. N-terminal truncations on the peptide agonist generate antagonists capable of binding to the extracellular domain, but not capable of activating full length receptor. The main objective of this study was to use Hydrogen/deuterium exchange (HDX) to identify how the amide hydrogen bonding network of peptide ligands and the extracellular domain of GLP-1R (nGLP-1R) were altered by binding interactions and to then use this platform to validate direct binding events for putative GLP-1R small molecule ligands. The HDX studies presented here for two glucagon-like peptide-1 receptor (GLP-1R) peptide ligands indicates that the antagonist exendin-4[9-39] is significantly destabilized in the presence of nonionic detergents as compared to the agonist exendin-4. Furthermore, HDX can detect stabilization of exendin-4 and exendin-4[9-39] hydrogen bonding networks at the N-terminal helix [Val19 to Lys27] upon binding to the N-terminal extracellular domain of GLP-1R (nGLP-1R). In addition we show hydrogen bonding network stabilization on nGLP-1R in response to ligand binding, and validate direct binding events with the extracellular domain of the receptor for putative GLP-1R small molecule ligands. PMID:25180755

  19. Effects of exendin-4 and selenium on the expression of GLP-1R, IRS-1, and preproinsulin in the pancreas of diabetic rats.

    PubMed

    Barakat, Ghinwa; Moustafa, Mohamed E; Khalifeh, Ibrahim; Hodroj, Mohammad H; Bikhazi, Anwar; Rizk, Sandra

    2016-08-01

    The mechanisms by which exendin-4 and selenium exert their antidiabetic actions are still unclear. Here, we investigated the effects of exendin-4 or selenium administration on the expression of glucagon-like peptide-1 receptor (GLP-1R), insulin receptor substrate-1 (IRS-1), and preproinsulin in the pancreas of diabetic rats. Diabetes was induced by streptozotocin administration. Diabetic rats were injected intraperitoneally with 0.03 μg exendin-4/kg body weight/daily or treated with 5 ppm selenium in drinking water for a period of 4 weeks. GLP-1R and IRS-1 levels were decreased while the level of preproinsulin messenger RNA (mRNA) was increased in the pancreas of diabetic untreated rats, as compared to that in control rats. Treatment of diabetic rats with exendin-4 increased protein and mRNA levels of GLP-1R, and IRS-1, and the mRNA level of preproinsulin in the pancreas, as compared to their levels in diabetic untreated rats. Selenium treatment of diabetic rats increased the pancreatic mRNA levels of GLP-1R, IRS-1, and preproinsulin. Exendin-4 or selenium treatment of diabetic rats also increased the numbers of pancreatic islets and GLP-1R molecules in the pancreas. Therefore, exendin-4 and selenium may exert their antidiabetic effects by increasing GLP-1R, IRS-1, and preproinsulin expression in the pancreas and by increasing the number of pancreatic islets.

  20. Insulin and Glucagon-Like Peptide 1 Receptor Agonist Combination Therapy in Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

    PubMed

    Maiorino, Maria Ida; Chiodini, Paolo; Bellastella, Giuseppe; Capuano, Annalisa; Esposito, Katherine; Giugliano, Dario

    2017-04-01

    The combination of basal insulin plus a glucagon-like peptide 1 receptor agonist (GLP-1RA) has been proposed as a treatment option to intensify insulin therapy in type 2 diabetes. We performed a meta-analysis of randomized controlled trials (RCTs) comparing this combination strategy to other injectable antidiabetes treatments on metabolic control in adult patients with type 2 diabetes. We conducted an electronic search until November 2016 on many electronic databases to identify RCTs assessing changes in HbA 1c , proportion of patients at HbA 1c target ≤7% (53 mmol/mol), hypoglycemia, and weight change. We used a random-effect model to calculate the weighted mean difference (WMD) or relative risk (RR) with the 95% CI. We identified 26 RCTs, lasting 12-52 weeks, and involving 11,425 patients. When the combination strategy was compared with other injectable treatments (overall data), there were reductions in HbA 1c (WMD = -0.47%, 95% CI -0.59 to -0.35), more patients at HbA 1c target (RR = 1.65, 95% CI 1.44-1.88), similar hypoglycemic events (RR = 1.14, 95% CI 0.93-1.39) and a reduction in weight (WMD = -2.5 kg, 95% CI -3.3 to -1.7), with high heterogeneity ( I 2 > 89%, P < 0.001) and a significant publication bias for three outcomes. In preplanned subgroup analyses, the combination treatment was similar to basal-bolus insulin regimens for glycemic control, with less hypoglycemia (RR = 0.66, 95% CI 0.46-0.93) and reduced weight (WMD = -4.7 kg, 95% CI -6.9 to -2.4). Fixed-ratio combinations yielded results similar to the overall analysis (HbA 1c WMD = -0.56%, 95% CI -0.72 to -0.40). GLP-1RAs alone or as titratable fixed-ratio combinations with basal insulin may represent a promising option to advance basal insulin therapy or to initiate injectable therapy in patients with type 2 diabetes inadequately controlled on oral agents. Longer studies are needed to assess durability and tolerability. © 2017 by the American Diabetes Association.

  1. Does endogenous GLP-1 affect resting energy expenditure and fuel selection in overweight and obese adults?

    PubMed

    Poggiogalle, E; Donini, L M; Chiesa, C; Pacifico, L; Lenzi, A; Perna, S; Faliva, M; Naso, M; Rondanelli, M

    2018-04-01

    To investigate the association between fasting glucagon-like peptide 1 (GLP-1) levels and resting energy expenditure (REE), and respiratory quotient (RQ) in overweight and obese adults. Study participants were enrolled at the Dietetic and Metabolic Unit, University of Pavia, Italy. Inclusion criteria were age ≥ 25 and ≤ 45 years, and body mass index (BMI) ≥ 25 and ≤ 35 kg/m 2 . Diabetic subjects were excluded. Body composition was measured by dual-energy X-ray absorptiometry. REE was evaluated using indirect calorimetry, and RQ was calculated from respiratory gas exchanges. Fasting GLP-1, glucose, insulin and free fatty acid (FFA) levels, and 24-h norepinephrine urinary excretion were measured. Homeostasis model assessments of insulin resistance (HOMA-IR) and beta-cell function (HOMA-β) were calculated. Thirty-seven participants were included (age 43.4 ± 1.6 years; BMI 30.6 ± 0.5 kg/m 2 ). REE was not associated with fasting GLP-1 levels (p = 0.98) after adjustment for age, sex, fat-free mass (FFM), and fat mass (FM). Similarly, no association was observed between RQ and GLP-1 levels (p = 0.95), after adjustment for age, sex, and body fat. In adults subjects with increased adiposity fasting, GLP-1 levels do not seem to play a role in the regulation of energy metabolism and in fuel selection.

  2. 99mTc Labeled Glucagon-Like Peptide-1-Analogue (99mTc-GLP1) Scintigraphy in the Management of Patients with Occult Insulinoma

    PubMed Central

    Sowa-Staszczak, Anna; Trofimiuk-Müldner, Małgorzata; Stefańska, Agnieszka; Tomaszuk, Monika; Buziak-Bereza, Monika; Gilis-Januszewska, Aleksandra; Jabrocka-Hybel, Agata; Głowa, Bogusław; Małecki, Maciej; Bednarczuk, Tomasz; Kamiński, Grzegorz; Kowalska, Aldona; Mikołajczak, Renata; Janota, Barbara; Hubalewska-Dydejczyk, Alicja

    2016-01-01

    Introduction The aim of this study was to assess the utility of [Lys40(Ahx-HYNIC-99mTc/EDDA)NH2]-exendin-4 scintigraphy in the management of patients with hypoglycemia, particularly in the detection of occult insulinoma. Materials and Methods Forty patients with hypoglycemia and increased/confusing results of serum insulin and C-peptide concentration and negative/inconclusive results of other imaging examinations were enrolled in the study. In all patients GLP-1 receptor imaging was performed to localise potential pancreatic lesions. Results Positive results of GLP-1 scintigraphy were observed in 28 patients. In 18 patients postsurgical histopathological examination confirmed diagnosis of insulinoma. Two patients had contraindications to the surgery, one patient did not want to be operated. One patient, who presented with postprandial hypoglycemia, with positive result of GLP-1 imaging was not qualified for surgery and is in the observational group. Eight patients were lost for follow up, among them 6 patients with positive GLP-1 scintigraphy result. One patient with negative scintigraphy was diagnosed with malignant insulinoma. In two patients with negative scintigraphy Munchausen syndrome was diagnosed (patients were taking insulin). Other seven patients with negative results of 99mTcGLP-1 scintigraphy and postprandial hypoglycemia with C-peptide and insulin levels within the limits of normal ranges are in the observational group. We would like to mention that 99mTc-GLP1-SPECT/CT was also performed in 3 pts with nesidioblastosis (revealing diffuse tracer uptake in two and a focal lesion in one case) and in two patients with malignant insulinoma (with the a focal uptake in the localization of a removed pancreatic headin one case and negative GLP-1 1 scintigraphy in the other patient). Conclusions 99mTc-GLP1-SPECT/CT could be helpful examination in the management of patients with hypoglycemia enabling proper localization of the pancreatic lesion and effective

  3. A novel GIP analogue, ZP4165, enhances glucagon-like peptide-1-induced body weight loss and improves glycaemic control in rodents.

    PubMed

    Nørregaard, Pia K; Deryabina, Maria A; Tofteng Shelton, Pernille; Fog, Jacob U; Daugaard, Jens R; Eriksson, Per-Olof; Larsen, Lone F; Jessen, Lene

    2018-01-01

    To investigate the effects of the novel glucose-dependent insulinotropic polypeptide (GIP) analogue, ZP4165, on body weight and glycaemic control in rodents, and to investigate if ZP4165 modulates the anti-obesity and anti-hyperglycaemic effects of a glucagon-like peptide-1 (GLP-1) agonist (liraglutide). The acute insulinotropic effect of ZP4165 was investigated in rats during an oral glucose tolerance test. The long-term effects of ZP4165 on body weight and glycaemic control, either alone or in combination with liraglutide, were assessed in diet-induced obese mice and diabetic db/db mice. ZP4165 showed insulinotropic action in rats. The GIP analogue did not alter the body weight of obese mice but enhanced GLP-1-induced weight loss. In diabetic mice, 4 weeks' dosing with ZP4165 reduced glycated haemoglobin levels vs vehicle by an extent similar to the GLP-1 agonist. ZP4165 potentiated the anti-obesity effect of a GLP-1 agonist in obese mice and improved glycaemic control in diabetic mice. These studies support further investigation of dual-incretin therapy as a more effective treatment option than mono GLP-1 medication for type 2 diabetes mellitus and obesity. © 2017 John Wiley & Sons Ltd.

  4. Feedback suppression of meal-induced glucagon-like peptide-1 (GLP-1) secretion mediated through elevations in intact GLP-1 caused by dipeptidyl peptidase-4 inhibition: a randomized, prospective comparison of sitagliptin and vildagliptin treatment.

    PubMed

    Baranov, Oleg; Kahle, Melanie; Deacon, Carolyn F; Holst, Jens J; Nauck, Michael A

    2016-11-01

    To compare directly the clinical effects of vildagliptin and sitagliptin in patients with type 2 diabetes, with a special emphasis on incretin hormones and L-cell feedback inhibition induced by dipeptidyl peptidase (DPP-4) inhibition. A total of 24 patients (12 on a diet/exercise regimen, 12 on metformin) were treated, in randomized order, for 7-9 days, with either vildagliptin (50 mg twice daily = 100 mg/d), sitagliptin (100 mg once daily in those on diet, 50 mg twice daily in those on metformin treatment = 100 mg/d) or placebo (twice daily). A mixed-meal test was performed. Intact glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide concentrations were doubled by both DPP-4 inhibitors. Meal-related total GLP-1 responses were reduced by vildagliptin and sitagliptin treatment alike in the majority of patients (vildagliptin: p = 0.0005; sitagliptin: p = 0.019), but with substantial inter-individual variation. L-cell feedback appeared to be more pronounced in those whose intact GLP-1 relative to total GLP-1 increased more, and who had greater reductions in fasting plasma glucose after DPP-4 inhibition. K-cell feedback inhibition overall was not significant. There were no differences in any of the clinical variables (glycaemia, insulin and glucagon secretory responses) between vildagliptin and sitagliptin treatment. Vildagliptin and sitagliptin affected incretin hormones, glucose concentrations, insulin and glucagon secretion in a similar manner. Inter-individual variations in L-cell feedback inhibition may indicate heterogeneity in the clinical response to DPP-4 inhibition. © 2016 John Wiley & Sons Ltd.

  5. Residues within the Transmembrane Domain of the Glucagon-Like Peptide-1 Receptor Involved in Ligand Binding and Receptor Activation: Modelling the Ligand-Bound Receptor

    PubMed Central

    Coopman, K.; Wallis, R.; Robb, G.; Brown, A. J. H.; Wilkinson, G. F.; Timms, D.

    2011-01-01

    The C-terminal regions of glucagon-like peptide-1 (GLP-1) bind to the N terminus of the GLP-1 receptor (GLP-1R), facilitating interaction of the ligand N terminus with the receptor transmembrane domain. In contrast, the agonist exendin-4 relies less on the transmembrane domain, and truncated antagonist analogs (e.g. exendin 9–39) may interact solely with the receptor N terminus. Here we used mutagenesis to explore the role of residues highly conserved in the predicted transmembrane helices of mammalian GLP-1Rs and conserved in family B G protein coupled receptors in ligand binding and GLP-1R activation. By iteration using information from the mutagenesis, along with the available crystal structure of the receptor N terminus and a model of the active opsin transmembrane domain, we developed a structural receptor model with GLP-1 bound and used this to better understand consequences of mutations. Mutation at Y152 [transmembrane helix (TM) 1], R190 (TM2), Y235 (TM3), H363 (TM6), and E364 (TM6) produced similar reductions in affinity for GLP-1 and exendin 9–39. In contrast, other mutations either preferentially [K197 (TM2), Q234 (TM3), and W284 (extracellular loop 2)] or solely [D198 (TM2) and R310 (TM5)] reduced GLP-1 affinity. Reduced agonist affinity was always associated with reduced potency. However, reductions in potency exceeded reductions in agonist affinity for K197A, W284A, and R310A, while H363A was uncoupled from cAMP generation, highlighting critical roles of these residues in translating binding to activation. Data show important roles in ligand binding and receptor activation of conserved residues within the transmembrane domain of the GLP-1R. The receptor structural model provides insight into the roles of these residues. PMID:21868452

  6. Pancreatic beta-cell responses to GLP-1 after near-normalization of blood glucose in patients with type 2 diabetes.

    PubMed

    Asmar, Meena; Højberg, Patricia V; Deacon, Carolyn F; Hare, Kristine; Holst, Jens J; Madsbad, Sten

    2010-02-25

    This study investigated the effects of strict glycaemic control on beta-cell function in nine obese subjects with type 2 diabetes (T2DM), using graded glucose infusions together with infusions of saline or GLP-1 before (HbA(1)c: 8.0+/-0.4%) and after four weeks of near-normalization of blood glucose (BG) using insulin (mean diurnal BG: 6.4+/-0.3 mmol/l; HbA(1)c: 6.6+/-0.3%). Nine matched healthy subjects acted as controls. In controls, area-under-curve (AUC) for amylin, C-peptide and proinsulin were higher with GLP-1 than saline (P<0.001). The AUC amylin/C-peptide ratio was similar on both days, while AUC proinsulin/C-peptide ratio was higher with GLP-1 (P=0.02). In the patients, amylin, C-peptide and proinsulin AUCs were unaltered by near-normoglycaemia per se. Proinsulin responses to GLP-1 were unchanged, but amylin and C-peptide AUCs increased (P<0.05) after insulin treatment, and AUC amylin/C-peptide ratios rose to control levels. Near-normoglycaemia tended to reduce AUC proinsulin/C-peptide ratio, which was significant (P=0.04) with GLP-1, but still higher than with saline (P=0.004). In conclusion, amylin, C-peptide and proinsulin responses to glucose were unaffected by four weeks of near-normoglycaemia, whereas GLP-1 increased amylin and C-peptide secretion and amylin/C-peptide ratio. Near-normoglycaemia reduced proinsulin/C-peptide ratio during stimulation with GLP-1, suggesting that strict glycaemic control might ameliorate some of the disturbances in beta-cell function characterizing T2DM. Copyright 2010 Elsevier B.V. All rights reserved.

  7. Regulation of Endogenous (Male) Rodent GLP-1 Secretion and Human Islet Insulin Secretion by Antagonism of Somatostatin Receptor 5.

    PubMed

    Farb, Thomas B; Adeva, Marta; Beauchamp, Thomas J; Cabrera, Over; Coates, David A; Meredith, Tamika DeShea; Droz, Brian A; Efanov, Alexander; Ficorilli, James V; Gackenheimer, Susan L; Martinez-Grau, Maria A; Molero, Victoriano; Ruano, Gema; Statnick, Michael A; Suter, Todd M; Syed, Samreen K; Toledo, Miguel A; Willard, Francis S; Zhou, Xin; Bokvist, Krister B; Barrett, David G

    2017-11-01

    Incretin and insulin responses to nutrient loads are suppressed in persons with diabetes, resulting in decreased glycemic control. Agents including sulfonylureas and dipeptidyl peptidase-4 inhibitors (DPP4i) partially reverse these effects and provide therapeutic benefit; however, their modes of action limit efficacy. Because somatostatin (SST) has been shown to suppress insulin and glucagonlike peptide-1 (GLP-1) secretion through the Gi-coupled SST receptor 5 (SSTR5) isoform in vitro, antagonism of SSTR5 may improve glycemic control via intervention in both pathways. Here, we show that a potent and selective SSTR5 antagonist reverses the blunting effects of SST on insulin secretion from isolated human islets, and demonstrate that SSTR5 antagonism affords increased levels of systemic GLP-1 in vivo. Knocking out Sstr5 in mice provided a similar increase in systemic GLP-1 levels, which were not increased further by treatment with the antagonist. Treatment of mice with the SSTR5 antagonist in combination with a DPP4i resulted in increases in systemic GLP-1 levels that were more than additive and resulted in greater glycemic control compared with either agent alone. In isolated human islets, the SSTR5 antagonist completely reversed the inhibitory effect of exogenous SST-14 on insulin secretion. Taken together, these data suggest that SSTR5 antagonism should increase circulating GLP-1 levels and stimulate insulin secretion (directly and via GLP-1) in humans, improving glycemic control in patients with diabetes. Copyright © 2017 Endocrine Society.

  8. Difference in protective effects of GIP and GLP-1 on endothelial cells according to cyclic adenosine monophosphate response.

    PubMed

    Lim, Dong-Mee; Park, Keun-Young; Hwang, Won-Min; Kim, Ju-Young; Kim, Byung-Joon

    2017-05-01

    Receptors for glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are present in vascular endothelial cells. Previous studies investigating euglycemic status have demonstrated that GIP is directly involved in the physiology of blood vessels by controlling the blood flow rate of portal veins and that GLP-1 has a protective effect on blood vessels by acting on endothelial cells. However, to the best of our knowledge, the effects of GIP and GLP-1 on endothelial cells in patients with hyperglycemia remain unknown. Therefore, the present study investigated whether the effect of the incretin hormones GLP-1 and GIP differed with regards to the reversal of endothelial cell dysfunction caused by hyperglycemia. The production of nitric oxide (NO) was measured using the Griess reagent system kit and the expression of cyclic adenosine monophosphate (cAMP) in the cell was measured at a wavelength of 405 nm with the ELISA reader using the cyclic AMP EIA kit. Exposure of human umbilical vein endothelial cells (HUVEC) to a high glucose concentration decreased NO and endothelial nitric oxide synthase (eNOS) levels but increased inducible NOS (iNOS) levels. However, when HUVECs were pretreated with GLP-1, a reduction of iNOS expression was observed and the expression of eNOS and NO were increased, as opposed to pretreatment with GIP. The results differed according to the response of cAMP, the second messenger of incretin hormones: The GIP pretreatment group did not exhibit an increase in cAMP levels while the GLP-1 pretreatment group did. The results of the present study provide evidence that GLP-1, but not GIP, has a protective effect on endothelial function associated with cardiovascular disease, as it is associated with increased eNOS expression and the levels of NO. This effect may be due to an increase in the cAMP concentration during hyperglycemic events.

  9. The downregulation of sweet taste receptor signaling in enteroendocrine L-cells mediates 3-deoxyglucosone-induced attenuation of high glucose-stimulated GLP-1 secretion.

    PubMed

    Wang, Fei; Song, Xiudao; Zhou, Liang; Liang, Guoqiang; Huang, Fei; Jiang, Guorong; Zhang, Lurong

    2017-12-26

    Sweet taste receptors (STRs) involve in regulating the release of glucose-stimulated glucagon-like peptide-1 (GLP-1). Our in vivo and in vitro studies found that 3-deoxyglucosone (3DG) inhibited glucose-stimulated GLP-1 secretion. This study investigated the role of STRs in 3DG-induced inhibition of high glucose-stimulated GLP-1 secretion. STC-1 cells were incubated with lactisole or 3DG for 1 h under 25 mM glucose conditions. Western blotting was used to study the expression of STRs signaling molecules and ELISA was used to analyse GLP-1 and cyclic adenosine monophosphate (cAMP) levels. Lactisole inhibited GLP-1 secretion. Exposure to 25 mM glucose increased the expressions of STRs subunits when compared with 5.6 mM glucose. 3DG decreased GLP-1 secretion and STRs subunits expressions, with affecting other components of STRs pathway, including the downregulation of transient receptor potential cation channel subfamily M member 5 (TRPM5) expression and the reduction of intracellular cAMP levels. 3DG attenuates high glucose-stimulated GLP-1 secretion by reducing STR subunit expression and downstream signaling components.

  10. Glucose Tolerance, Lipids, and GLP-1 Secretion in JCR:LA-cp Rats Fed a High Protein Fiber Diet

    PubMed Central

    Reimer, Raylene A.; Russell, James C.

    2013-01-01

    Background We have shown that individually, dietary fiber and protein increase secretion of the anorexigenic and insulinotropic hormone, glucagon-like peptide-1 (GLP-1). Objective Our objective was to combine, in one diet, high levels of fiber and protein to maximize GLP-1 secretion, improve glucose tolerance, and reduce weight gain. Methods and Procedures Lean (+/?) and obese (cp/cp) male James C Russell corpulent (JCR:LA-cp) rats lacking a functional leptin receptor were fed one of four experimental diets (control, high protein (HP), high fiber (HF, prebiotic fiber inulin), or combination (CB)) for 3 weeks. An oral glucose tolerance test (OGTT) was performed to evaluate plasma GLP-1, insulin and glucose. Plasma lipids and intestinal proglucagon mRNA expression were determined. Results Energy intake was lower with the HF diet in lean and obese rats. Weight gain did not differ between diets. Higher colonic proglucagon mRNA in lean rats fed a CB diet was associated with higher GLP-1 secretion during OGTT. The HP diet significantly reduced plasma glucose area under the curve (AUC) during OGTT in obese rats, which reflected both an increased GLP-1 AUC and higher fasting insulin. Diets containing inulin resulted in the lowest plasma triglyceride and total cholesterol levels. Discussion Overall, combining HP with HF in the diet increased GLP-1 secretion in response to oral glucose, but did not improve glucose tolerance or lipid profiles more than the HF diet alone did. We also suggest that glycemic and insulinemic response to prebiotics differ among rat models and future research work should examine their role in improving glucose tolerance in diet-induced vs. genetic obesity with overt hyperleptinemia. PMID:18223610

  11. Coagonist of GLP-1 and glucagon decreases liver inflammation and atherosclerosis in dyslipidemic condition.

    PubMed

    Patel, Vishal; Joharapurkar, Amit; Kshirsagar, Samadhan; Sutariya, Brijesh; Patel, Maulik; Pandey, Dheerendra; Patel, Hiren; Ranvir, Ramchandra; Kadam, Shekhar; Patel, Dipam; Bahekar, Rajesh; Jain, Mukul

    2018-02-25

    Dyslipidemia enhances progression of atherosclerosis. Coagonist of GLP-1 and glucagon are under clinical investigation for the treatment of obesity and diabetes. Earlier, we have observed that coagonist reduced circulating and hepatic lipids, independent of its anorexic effects. Here, we investigated the role of coagonist of GLP-1 and glucagon receptors in complications of diet-induced dyslipidemia in hamsters and humanized double transgenic mice. Hamsters fed on high fat high cholesterol diet were treated for 8 weeks with coagonist of GLP-1 and glucagon receptors (75 and 150 μg/kg). Pair-fed control was maintained. Cholesterol fed transgenic mice overexpressing hApoB100 and hCETP with coagonist (300 μg/kg) for 4 weeks. After the completion of treatment, biochemical estimations were done. Coagonist treatment reduced triglycerides in plasma, liver and aorta, plasma cholesterol and hepatic triglyceride secretion rate. Expressions of HMG-CoA reductase and SBREBP-1C were reduced and expressions of LDLR, CYP7A1, ABCA1 and ABCB11 were increased in liver, due to coagonist treatment. Coagonist treatment increased bile flow rate and biliary cholesterol excretion. IL-6 and TNF-α were reduced in plasma and expression of TNF-α, MCP-1, MMP-9 and TIMP-1 decreased in liver. Treatment with coagonist reduced oxidative stress in liver and aorta. Energy expenditure was increased and respiratory quotient was reduced by coagonist treatment. These changes were correlated with reduced hepatic inflammation and lipids in liver and aorta in coagonist treated hamsters. Coagonist treatment also reduced lipids in cholesterol-fed transgenic mice. These changes were independent of glycaemia and anorexia observed after coagonist treatment. Long term treatment with coagonist of GLP-1 and glucagon receptor ameliorated diet-induced dyslipidemia and atherosclerosis by regulating bile homeostasis, liver inflammation and energy expenditure. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Elevated Postoperative Endogenous GLP-1 Levels Mediate Effects of Roux-en-Y Gastric Bypass on Neural Responsivity to Food Cues.

    PubMed

    Ten Kulve, Jennifer S; Veltman, Dick J; Gerdes, Victor E A; van Bloemendaal, Liselotte; Barkhof, Frederik; Deacon, Carolyn F; Holst, Jens J; Drent, Madeleine L; Diamant, Michaela; IJzerman, Richard G

    2017-11-01

    It has been suggested that weight reduction and improvements in satiety after Roux-en-Y gastric bypass (RYGB) are partly mediated via postoperative neuroendocrine changes. Glucagon-like peptide-1 (GLP-1) is a gut hormone secreted after food ingestion and is associated with appetite and weight reduction, mediated via effects on the central nervous system (CNS). Secretion of GLP-1 is greatly enhanced after RYGB. We hypothesized that postoperative elevated GLP-1 levels contribute to the improved satiety regulation after RYGB via effects on the CNS. Effects of the GLP-1 receptor antagonist exendin 9-39 (Ex9-39) and placebo were assessed in 10 women before and after RYGB. We used functional MRI to investigate CNS activation in response to visual food cues (pictures) and gustatory food cues (consumption of chocolate milk), comparing results with Ex9-39 versus placebo before and after RYGB. After RYGB, CNS activation was reduced in the rolandic operculum and caudate nucleus in response to viewing food pictures ( P = 0.03) and in the insula in response to consumption of palatable food ( P = 0.003). GLP-1 levels were significantly elevated postoperatively ( P < 0.001). After RYGB, GLP-1 receptor blockade resulted in a larger increase in activation in the caudate nucleus in response to food pictures ( P = 0.02) and in the insula in response to palatable food consumption ( P = 0.002). We conclude that the effects of RYGB on CNS activation in response to visual and gustatory food cues may be mediated by central effects of GLP-1. Our findings provide further insights into the mechanisms underlying the weight-lowering effects of RYGB. © 2017 by the American Diabetes Association.

  13. Roles of increased glycaemic variability, GLP-1 and glucagon in hypoglycaemia after Roux-en-Y gastric bypass

    PubMed Central

    Tharakan, George; Behary, Preeshila; Wewer Albrechtsen, Nicolai J; Chahal, Harvinder; Kenkre, Julia; Miras, Alexander D; Ahmed, Ahmed R; Holst, Jens J; Bloom, Stephen R

    2017-01-01

    Objective Roux-en-Y gastric bypass (RYGB) surgery is currently the most effective treatment for diabetes and obesity. An increasingly recognized and highly disabling complication of RYGB is postprandial hypoglycaemia (PPH). The pathophysiology of PPH remains unclear with multiple mechanisms suggested including nesidioblastosis, altered insulin clearance and increased glucagon-like peptide-1 (GLP-1) secretion. Whilst many PPH patients respond to dietary modification, some have severely disabling symptoms. Multiple treatments are proposed, including dietary modification, GLP-1 antagonism, GLP-1 analogues and even surgical reversal, with none showing a more decided advantage over the others. A greater understanding of the pathophysiology of PPH could guide the development of new therapeutic strategies. Methods We studied a cohort of PPH patients at the Imperial Weight Center. We performed continuous glucose monitoring to characterize their altered glycaemic variability. We also performed a mixed meal test (MMT) and measured gut hormone concentrations. Results We found increased glycaemic variability in our cohort of PPH patients, specifically a higher mean amplitude glucose excursion (MAGE) score of 4.9. We observed significantly greater and earlier increases in insulin, GLP-1 and glucagon in patients who had hypoglycaemia in response to an MMT (MMT Hypo) relative to those that did not (MMT Non-Hypo). No significant differences in oxyntomodulin, GIP or peptide YY secretion were seen between these two groups. Conclusion An early peak in GLP-1 and glucagon may together trigger an exaggerated insulinotropic response to eating and consequent hypoglycaemia in patients with PPH. PMID:28855269

  14. Influences of Dietary Added Sugar Consumption on Striatal Food-Cue Reactivity and Postprandial GLP-1 Response

    PubMed Central

    Dorton, Hilary M.; Luo, Shan; Monterosso, John R.; Page, Kathleen A.

    2018-01-01

    Sugar consumption in the United States exceeds recommendations from the American Heart Association. Overconsumption of sugar is linked to risk for obesity and metabolic disease. Animal studies suggest that high-sugar diets alter functions in brain regions associated with reward processing, including the dorsal and ventral striatum. Human neuroimaging studies have shown that these regions are responsive to food cues, and that the gut-derived satiety hormones, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY), suppress striatal food-cue responsivity. We aimed to determine the associations between dietary added sugar intake, striatal responsivity to food cues, and postprandial GLP-1 and PYY levels. Twenty-two lean volunteers underwent a functional magnetic resonance imaging (fMRI) scan during which they viewed pictures of food and non-food items after a 12-h fast. Before scanning, participants consumed a glucose drink. A subset of 19 participants underwent an additional fMRI session in which they consumed water as a control condition. Blood was sampled for GLP-1, and PYY levels and hunger ratings were assessed before and ~75 min after drink consumption. In-person 24-h dietary recalls were collected from each participant on three to six separate occasions over a 2-month period. Average percent calories from added sugar were calculated using information from 24-h dietary recalls. A region-of-interest analysis was performed to compare the blood oxygen level-dependent (BOLD) response to food vs. non-food cues in the bilateral dorsal striatum (caudate/putamen) and ventral striatum (nucleus accumbens). The relationships between added sugar, striatal responses, and hormone changes after drink consumption were assessed using Spearman’s correlations. We observed a positive correlation between added sugar intake and BOLD response to food cues in the dorsal striatum and a similar trend in the nucleus accumbens after glucose, but not water, consumption. Added sugar intake

  15. Influences of Dietary Added Sugar Consumption on Striatal Food-Cue Reactivity and Postprandial GLP-1 Response.

    PubMed

    Dorton, Hilary M; Luo, Shan; Monterosso, John R; Page, Kathleen A

    2017-01-01

    Sugar consumption in the United States exceeds recommendations from the American Heart Association. Overconsumption of sugar is linked to risk for obesity and metabolic disease. Animal studies suggest that high-sugar diets alter functions in brain regions associated with reward processing, including the dorsal and ventral striatum. Human neuroimaging studies have shown that these regions are responsive to food cues, and that the gut-derived satiety hormones, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY), suppress striatal food-cue responsivity. We aimed to determine the associations between dietary added sugar intake, striatal responsivity to food cues, and postprandial GLP-1 and PYY levels. Twenty-two lean volunteers underwent a functional magnetic resonance imaging (fMRI) scan during which they viewed pictures of food and non-food items after a 12-h fast. Before scanning, participants consumed a glucose drink. A subset of 19 participants underwent an additional fMRI session in which they consumed water as a control condition. Blood was sampled for GLP-1, and PYY levels and hunger ratings were assessed before and ~75 min after drink consumption. In-person 24-h dietary recalls were collected from each participant on three to six separate occasions over a 2-month period. Average percent calories from added sugar were calculated using information from 24-h dietary recalls. A region-of-interest analysis was performed to compare the blood oxygen level-dependent (BOLD) response to food vs. non-food cues in the bilateral dorsal striatum (caudate/putamen) and ventral striatum (nucleus accumbens). The relationships between added sugar, striatal responses, and hormone changes after drink consumption were assessed using Spearman's correlations. We observed a positive correlation between added sugar intake and BOLD response to food cues in the dorsal striatum and a similar trend in the nucleus accumbens after glucose, but not water, consumption. Added sugar intake

  16. The pepper GNA-related lectin and PAN domain protein gene, CaGLP1, is required for plant cell death and defense signaling during bacterial infection.

    PubMed

    Kim, Nak Hyun; Lee, Dong Hyuk; Choi, Du Seok; Hwang, Byung Kook

    2015-12-01

    Carbohydrate-binding proteins, commonly referred to as lectins or agglutinins, function in defense responses to microbial pathogens. Pepper (Capsicum annuum) GNA-related lectin and PAN-domain protein gene CaGLP1 was isolated and functionally characterized from pepper leaves infected with Xanthomonas campestris pv. vesicatoria (Xcv). CaGLP1 contained an amine-terminus prokaryotic membrane lipoprotein lipid attachment site, a Galanthus nivalis agglutinin (GNA)-related lectin domain responsible for the recognition of high-mannose N-glycans, and a carboxyl-terminus PAN/apple domain. RNA gel blot and immunoblot analyses determined that CaGLP1 was strongly induced in pepper by compatible and incompatible Xcv infection. CaGLP1 protein localized primarily to the plasma membrane and exhibited mannose-binding specificity. CaGLP1-silenced pepper plants were more susceptible to compatible or incompatible Xcv infection compared with that of non-silenced control plants. CaGLP1 silencing in pepper leaves did not accumulate H2O2 and induce cell death during incompatible Xcv infection. Defense-related CaDEF1 (defensin) gene expression was significantly reduced in CaGLP1-silenced pepper plants. CaGLP1-overexpression in Arabidopsis thaliana enhanced resistance to Pseudomonas syringae pv. tomato. Defense-related AtPDF1.2 expression was elevated in CaGLP1-overexpression lines. Together, these results suggest that CaGLP1 is required for plant cell death and defense responses through the reactive oxygen species burst and downstream defense-related gene expression in response to bacterial pathogen challenge. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Effects of the glucagon-like polypeptide-1 analogue (Val8)GLP-1 on learning, progenitor cell proliferation and neurogenesis in the C57B/16 mouse brain.

    PubMed

    McGovern, Stephen F J; Hunter, Kerry; Hölscher, Christian

    2012-09-14

    Type 2 diabetes (T2DM) has been identified as a risk factor for Alzheimer's disease. Here, we tested the properties of the glucagon-like polypetide-1 (GLP-1) analogue (Val8)GLP-1, a drug originally developed as a treatment for T2DM at a range of doses (2.5 nmol; 25 nmol; 100 nmol; or 250 nmol/kg bw ip.) in an acute memory study in wild type C57B/l6 mice. We also tested (Val8)GLP-1 and the GLP-1 receptor antagonist exendin (9-39) in a chronic study (3 weeks at 25 nmol/kg bw ip. once-daily). We found that (Val8)GLP-1 crossed the blood brain barrier readily and that peripheral injection increased levels in the brain 30 min post-injection ip. but not 2h post-injection in rats. In the acute study, the low dose of 2.5 nmol/kg ip. enhanced motor activity in the open field task, while total distance travelled, exploratory behaviour and anxiety was not affected at any dose. Learning an object recognition task was not affected either. In the chronic study, no effect was observed in the open field assessment. The antagonist exendin (9-39) impaired object recognition learning and spatial learning in a water maze task, demonstrating the importance of GLP-1 signalling in memory formation. Locomotor activity was also affected in some cases. Blood sugar levels and insulin sensitivity was not affected in chronically treated mice. Neuronal stem cells and neurogenesis was enhanced by (Val8)GLP-1 in the dentate gyrus of wild type mice. The results demonstrate that (Val8)GLP-1 is safe in a range of doses, crosses the BBB and has potentially beneficial effects in the CNS by enhancing neurogenesis. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Helixconstraints and amino acid substitution in GLP-1 increase cAMP and insulin secretion but not beta-arrestin 2 signaling.

    PubMed

    Plisson, Fabien; Hill, Timothy A; Mitchell, Justin M; Hoang, Huy N; de Araujo, Aline D; Xu, Weijun; Cotterell, Adam; Edmonds, David J; Stanton, Robert V; Derksen, David R; Loria, Paula M; Griffith, David A; Price, David A; Liras, Spiros; Fairlie, David P

    2017-02-15

    Glucagon-like peptide (GLP-1) is an endogenous hormone that induces insulin secretion from pancreatic islets and modified forms are used to treat diabetes mellitus type 2. Understanding how GLP-1 interacts with its receptor (GLP-1R) can potentially lead to more effective drugs. Modeling and NMR studies of the N-terminus of GLP-1 suggest a β-turn between residues Glu9-Phe12 and a kinked alpha helix between Val16-Gly37. N-terminal turn constraints attenuated binding affinity and activity (compounds 1-8). Lys-Asp (i, i+4) crosslinks in the middle and at the C-terminus increased alpha helicity and cAMP stimulation without much effect on binding affinity or beta-arrestin 2 recruitment (compounds 9-18). Strategic positioning of helix-inducing constraints and amino acid substitutions (Tyr16, Ala22) increased peptide helicity and produced ten-fold higher cAMP potency (compounds 19-28) over GLP-1(7-37)-NH 2 . The most potent cAMP activator (compound 23) was also the most potent inducer of insulin secretion. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  19. Treatment patterns in patients with type 2 diabetes mellitus treated with glucagon-like peptide-1 receptor agonists: Higher adherence and persistence with dulaglutide compared with once-weekly exenatide and liraglutide.

    PubMed

    Alatorre, Carlos; Fernández Landó, Laura; Yu, Maria; Brown, Katelyn; Montejano, Leslie; Juneau, Paul; Mody, Reema; Swindle, Ralph

    2017-07-01

    To compare adherence (proportion of days covered [PDC]), persistence, and treatment patterns among patients with type 2 diabetes mellitus (T2DM) newly initiating glucagon-like peptide-1 receptor agonists (GLP-1RAs). More specifically, the main objectives were to compare dulaglutide vs exenatide once weekly and dulaglutide vs liraglutide. Patients with T2DM newly initiating dulaglutide, albiglutide, exenatide once weekly, exenatide twice daily and liraglutide between November 2014 and April 2015 were hierarchically selected from Truven Health's MarketScan Research Databases. Propensity score matching was used to account for selection bias. Adherence to and persistence with the index GLP-1RA, and switching and augmentation patterns were assessed during the 6-month post-index period. Mean adherence for the matched cohorts was significantly higher for dulaglutide than for exenatide once weekly (0.72 vs 0.61; P  < .0001) and liraglutide (0.71 vs 0.67; P  < .0001). The percentage of patients achieving PDC ≥ 0.80 was significantly higher for dulaglutide compared with exenatide once weekly (54.2% vs 37.9%; P  < .0001) and liraglutide (53.5% vs 44.3%; P  < .0001). The mean (standard deviation) days on treatment for all matched patients was significantly higher for patients in the dulaglutide cohort compared with those in the exenatide once-weekly (148.4 [55.4] vs 123.6 [61.6]; P  < .0001) and liraglutide cohorts (146.0 [56.9] vs 137.4 [60.1]; P  < .0001). A significantly lower proportion of patients on dulaglutide discontinued treatment compared with those on exenatide once weekly (26.2% vs 48.4%; P  < .0001) and those on liraglutide (28.0% vs 35.6%; P  < .0001). Dulaglutide initiators had significantly higher adherence, were more persistent, and had lower discontinuation rates compared with initiators of exenatide once weekly or liraglutide during the 6-month follow-up period. © 2017 Eli Lilly and Company. Diabetes, Obesity and

  20. Minireview: Signal Bias, Allosterism, and Polymorphic Variation at the GLP-1R: Implications for Drug Discovery

    PubMed Central

    Koole, Cassandra; Savage, Emilia E.; Christopoulos, Arthur; Miller, Laurence J.

    2013-01-01

    The glucagon-like peptide-1 receptor (GLP-1R) controls the physiological responses to the incretin hormone glucagon-like peptide-1 and is a major therapeutic target for the treatment of type 2 diabetes, owing to the broad range of effects that are mediated upon its activation. These include the promotion of glucose-dependent insulin secretion, increased insulin biosynthesis, preservation of β-cell mass, improved peripheral insulin action, and promotion of weight loss. Regulation of GLP-1R function is complex, with multiple endogenous and exogenous peptides that interact with the receptor that result in the activation of numerous downstream signaling cascades. The current understanding of GLP-1R signaling and regulation is limited, with the desired spectrum of signaling required for the ideal therapeutic outcome still to be determined. In addition, there are several single-nucleotide polymorphisms (used in this review as defining a natural change of single nucleotide in the receptor sequence; clinically, this is viewed as a single-nucleotide polymorphism only if the frequency of the mutation occurs in 1% or more of the population) distributed within the coding sequence of the receptor protein that have the potential to produce differential responses for distinct ligands. In this review, we discuss the current understanding of GLP-1R function, in particular highlighting recent advances in the field on ligand-directed signal bias, allosteric modulation, and probe dependence and the implications of these behaviors for drug discovery and development. PMID:23864649

  1. Treatment of antipsychotic-associated obesity with a GLP-1 receptor agonist—protocol for an investigator-initiated prospective, randomised, placebo-controlled, double-blinded intervention study: the TAO study protocol

    PubMed Central

    Ishøy, Pelle L; Knop, Filip K; Broberg, Brian V; Baandrup, Lone; Fagerlund, Birgitte; Jørgensen, Niklas R; Andersen, Ulrik B; Rostrup, Egill; Glenthøj, Birte Y; Ebdrup, Bjørn H

    2014-01-01

    Introduction Antipsychotic medication is widely associated with dysmetabolism including obesity and type 2 diabetes, cardiovascular-related diseases and early death. Obesity is considered the single most important risk factor for cardiovascular morbidity and mortality. Interventions against antipsychotic-associated obesity are limited and insufficient. Glucagon-like peptide-1 (GLP-1) receptor agonists are approved for the treatment of type 2 diabetes, but their bodyweight-lowering effects have also been recognised in patients with non-diabetes. The primary endpoint of this trial is weight loss after 3 months of treatment with a GLP-1 receptor agonist (exenatide once weekly) in patients with non-diabetic schizophrenia with antipsychotic-associated obesity. Secondary endpoints include physiological and metabolic measurements, various psychopathological and cognitive measures, and structural and functional brain MRI. Methods and analysis 40 obese patients with schizophrenia or schizoaffective disorder treated with antipsychotic drugs will be randomised to subcutaneous injection of exenatide once weekly (2 mg) or placebo for 3 months, adjunctive to their antipsychotic treatment. Ethics and dissemination The trial has been approved by the Danish Health and Medicines Authority, the National Committee on Health Research Ethics and the Danish Data Protection Agency. Trial participation presupposes theoral and written patient informed consent. An external, independent monitoring committee (Good Clinical Practice Unit at Copenhagen University Hospital) will monitor the study according to the GCP Guidelines. Trial data, including positive, negative and inconclusive results, will be presented at national and international scientific meetings and conferences. Papers will be submitted to peer-reviewed journals. Trial registration ClinicalTrials.gov identifier: NCT01794429; National Committee on Health Research Ethics project number: 36378; EudraCT nr: 2012-005404-17; The

  2. Water Permeation Across Biological Membranes: Mechanism and Dynamics of Aquaporin-1 and GlpF

    NASA Astrophysics Data System (ADS)

    de Groot, Bert L.; Grubmüller, Helmut

    2001-12-01

    ``Real time'' molecular dynamics simulations of water permeation through human aquaporin-1 (AQP1) and the bacterial glycerol facilitator GlpF are presented. We obtained time-resolved, atomic-resolution models of the permeation mechanism across these highly selective membrane channels. Both proteins act as two-stage filters: Conserved fingerprint [asparagine-proline-alanine (NPA)] motifs form a selectivity-determining region; a second (aromatic/arginine) region is proposed to function as a proton filter. Hydrophobic regions near the NPA motifs are rate-limiting water barriers. In AQP1, a fine-tuned water dipole rotation during passage is essential for water selectivity. In GlpF, a glycerol-mediated ``induced fit'' gating motion is proposed to generate selectivity for glycerol over water.

  3. Liraglutide and Dulaglutide therapy in addition to SGLT-2 inhibitor and metformin treatment in Indian type 2 diabetics: a real world retrospective observational study.

    PubMed

    Ghosal, S; Sinha, B

    2018-01-01

    Therapy for Type 2 diabetes (T2D) has been transformed by the introduction of newer agents like Glucagon like Peptide Receptor Agonists (GLP-1RA) and Sodium-glucose linked transporter inhibitors (SGLT2i). However with co-initiation of SGLT2i and GLP-1RA in the DURATION 8 trial an improvement in HbA1c was noted but the beneficial effect was not equal to the sum of its parts. In view of this we proceeded to test the hypothesis that sequential addition of GLP-1RA therapy to metformin and SGLT-2i may be more beneficial. A retrospective real world observational case note study conducted in two diabetes care centres in India analyzed the first 60 consecutive T2D patients who could afford this therapy and had not achieved their glycaemic target (HbA1c < 7%)on metformin and SGLT2i. All these patients were additionally treated with either Dulaglutide or Liraglutide and followed up for 13 weeks. Across the entire 13-week study period, both liraglutide and dulaglutide proved to be an excellent add on to metformin and SGLT-2 inhibitor. There was significant reduction in HbA1c and body weight. Liraglutide had an additional significant impact on systolic blood pressure reduction in contrast to the dulaglutide arm. Comparatively, liraglutide and dulaglutide achieved similar metabolic control. However, a larger proportion of patients achieved HbA1c below 7.0% in the liraglutide arm (63.3%) compared to the dulaglutide arm (30%) and this difference was statistically significant. In this retrospective study in Indian type 2 diabetic patients poorly controlled with metformin and SGLT-2 inhibitor we found a meaningful impact of adding a GLP-1 RA on all metabolic parameters. There were additional advantages seen with liraglutide as far achieving target HbA1c of less than 7% and also on the quantum of weight loss and systolic blood pressure reduction.

  4. Appetite-related peptides in childhood and adolescence: role of ghrelin, PYY, and GLP-1.

    PubMed

    Horner, Katy; Lee, SoJung

    2015-11-01

    During childhood and adolescence, a number of factors, including age, puberty, sex, race, and body composition, may contribute to differences in satiety, food intake, and appetite-related peptides. These peptides include the orexigenic peptide ghrelin and anorexigenic gut peptides peptide YY (PYY) and glucagon-like peptide-1 (GLP-1). For example, lower fasting ghrelin levels, lower postprandial ghrelin suppression, and blunted PYY and GLP-1 responses to food intake could contribute to a dysregulation of appetite in already obese children and adolescents. Whereas, changes in these peptides observed during puberty could facilitate growth. A greater understanding of the major moderating factors of appetite-related peptides in the pediatric population is essential to improve interpretation of study findings and for effective tailoring of strategies targeting appetite control to individuals. While more studies are needed, there is some evidence to suggest that exercise-based lifestyle interventions could be a potential therapeutic strategy to improve appetite-peptide profiles in overweight and obese children and adolescents. The aim of this review is (i) to discuss the potential moderating factors of ghrelin, PYY, and GLP-1, including age and puberty, sex, race and body composition; and (ii) to examine the effects of exercise interventions on these appetite-related gut peptides in children and adolescents.

  5. GLP-1 receptor signaling is not required for reduced body weight after RYGB in rodents

    PubMed Central

    Ye, Jianping; Hao, Zheng; Mumphrey, Michael B.; Townsend, R. Leigh; Patterson, Laurel M.; Stylopoulos, Nicholas; Münzberg, Heike; Morrison, Christopher D.; Drucker, Daniel J.

    2014-01-01

    Exaggerated GLP-1 and PYY secretion is thought to be a major mechanism in the reduced food intake and body weight after Roux-en-Y gastric bypass surgery. Here, we use complementary pharmacological and genetic loss-of-function approaches to test the role of increased signaling by these gut hormones in high-fat diet-induced obese rodents. Chronic brain infusion of a supramaximal dose of the selective GLP-1 receptor antagonist exendin-9–39 into the lateral cerebral ventricle significantly increased food intake and body weight in both RYGB and sham-operated rats, suggesting that, while contributing to the physiological control of food intake and body weight, central GLP-1 receptor signaling tone is not the critical mechanism uniquely responsible for the body weight-lowering effects of RYGB. Central infusion of the selective Y2R-antagonist BIIE0246 had no effect in either group, suggesting that it is not critical for the effects of RYGB on body weight under the conditions tested. In a recently established mouse model of RYGB that closely mimics surgery and weight loss dynamics in humans, obese GLP-1R-deficient mice lost the same amount of body weight and fat mass and maintained similarly lower body weight compared with wild-type mice. Together, the results surprisingly provide no support for important individual roles of either gut hormone in the specific mechanisms by which RYGB rats settle at a lower body weight. It is likely that the beneficial effects of bariatric surgeries are expressed through complex mechanisms that require combination approaches for their identification. PMID:24430883

  6. GLP-1 receptor signaling is not required for reduced body weight after RYGB in rodents.

    PubMed

    Ye, Jianping; Hao, Zheng; Mumphrey, Michael B; Townsend, R Leigh; Patterson, Laurel M; Stylopoulos, Nicholas; Münzberg, Heike; Morrison, Christopher D; Drucker, Daniel J; Berthoud, Hans-Rudolf

    2014-03-01

    Exaggerated GLP-1 and PYY secretion is thought to be a major mechanism in the reduced food intake and body weight after Roux-en-Y gastric bypass surgery. Here, we use complementary pharmacological and genetic loss-of-function approaches to test the role of increased signaling by these gut hormones in high-fat diet-induced obese rodents. Chronic brain infusion of a supramaximal dose of the selective GLP-1 receptor antagonist exendin-9-39 into the lateral cerebral ventricle significantly increased food intake and body weight in both RYGB and sham-operated rats, suggesting that, while contributing to the physiological control of food intake and body weight, central GLP-1 receptor signaling tone is not the critical mechanism uniquely responsible for the body weight-lowering effects of RYGB. Central infusion of the selective Y2R-antagonist BIIE0246 had no effect in either group, suggesting that it is not critical for the effects of RYGB on body weight under the conditions tested. In a recently established mouse model of RYGB that closely mimics surgery and weight loss dynamics in humans, obese GLP-1R-deficient mice lost the same amount of body weight and fat mass and maintained similarly lower body weight compared with wild-type mice. Together, the results surprisingly provide no support for important individual roles of either gut hormone in the specific mechanisms by which RYGB rats settle at a lower body weight. It is likely that the beneficial effects of bariatric surgeries are expressed through complex mechanisms that require combination approaches for their identification.

  7. Flavonoid-rich extract of Chromolaena odorata modulate circulating GLP-1 in Wistar rats: computational evaluation of TGR5 involvement.

    PubMed

    Omotuyi, Olaposi Idowu; Nash, Oyekanmi; Inyang, Olumide Kayode; Ogidigo, Joyce; Enejoh, Ojochenemi; Okpalefe, Okiemute; Hamada, Tsuyoshi

    2018-02-01

    Chromolaena odorata is a major bio-resource in folkloric treatment of diabetes. In the present study, its anti-diabetic component and underlying mechanism were investigated. A library containing 140 phytocompounds previously characterized from C. odorata was generated and docked (Autodock Vina) into homology models of dipeptidyl peptidase (DPP)-4, Takeda-G-protein-receptor-5 (TGR5), glucagon-like peptide 1 (GLP1) receptor, renal sodium dependent glucose transporter (SGLUT)-1/2 and nucleotide-binding oligomerization domain (NOD) proteins 1&2. GLP-1 gene (RT-PCR) modulation and its release (EIA) by C. odorata were confirmed in vivo. From the docking result above, TGR5 was identified as a major target for two key C. odorata flavonoids (5,7-dihydroxy-6-4-dimethoxyflavanone and homoesperetin-7-rutinoside); sodium taurocholate and C. odorata powder included into the diet of the animals both raised the intestinal GLP-1 expression versus control ( p  < 0.05); When treated with flavonoid-rich extract of C. odorata (CoF) or malvidin, circulating GLP-1 increased by 130.7% in malvidin-treated subjects (0 vs. 45 min). CoF treatment also resulted in 128.5 and 275% increase for 10 and 30 mg/kg b.w., respectively. The results of this study support that C. odorata flavonoids may modulate the expression of GLP-1 and its release via TGR5. This finding may underscore its anti-diabetic potency.

  8. Influence of the IL-1Ra gene polymorphism on in vivo synthesis of IL-1Ra and IL-1beta after live yellow fever vaccination.

    PubMed

    Hacker, U T; Erhardt, S; Tschöp, K; Jelinek, T; Endres, S

    2001-09-01

    The inflammatory response in infectious and autoimmune diseases is regulated by the balance between pro- and anti-inflammatory cytokines. The IL-1 complex contains polymorphic genes coding for IL-1alpha, IL-1beta and IL-1Ra. The IL-1Ra (variable number of tanden repeat) VNTR polymorphism has been shown to influence the capacity to produce IL-1beta and IL-1Ra after in vitro stimulation. Allele 2 of this polymorphism is associated with a number of inflammatory diseases. To determine the impact of the IL-1Ra polymorphism on in vivo human cytokine synthesis, we used a yellow fever vaccination model for the induction of cytokine synthesis in healthy volunteers. Two different yellow fever vaccines were used. After administration of the RKI vaccine (34 volunteers), plasma TNF-alpha concentration increased from 13.4 +/- 0.9 pg/ml to 23.3 +/- 1.1 pg/ml (P < 0.001), and plasma IL-1Ra concentration increased from 308 +/- 25 pg/ml to 1019 +/- 111 pg/ml (P < 0.001), on day 2. Using Stamaril vaccine, no increase in the plasma concentrations of either TNF-alpha or IL-1Ra could be detected (n = 17). Only the RKI vaccine induced TNF-alpha synthesis after in vitro stimulation of MNC. Carriers of allele 2 of the IL-1Ra polymorphism had increased baseline concentrations of IL-1Ra (350 +/- 32 pg/ml) compared with non-carriers (222 +/- 18 pg/ml, P < 0.001), and decreased concentrations of IL-1beta (0.9 +/- 0.2 pg/ml for carriers versus 2.8 +/- 0.7 pg/ml for non-carriers, P = 0.017). After yellow fever vaccination (RKI vaccine), no significant differences in the increase of IL-1Ra plasma levels were detected between carriers and non-carriers of allele 2 of the IL-1Ra gene polymorphism. This is the first study to examine the influence of this genetic polymorphism on in vivo-induced human IL-1beta and IL-1Ra synthesis. Baseline concentrations of IL-1Ra and IL-1beta were significantly influenced by the IL-1Ra polymorphism. No influence of the IL-1Ra polymorphism on the in vivo

  9. Direct control of peripheral lipid deposition by CNS GLP-1 receptor signaling is mediated by the sympathetic nervous system and blunted in diet-induced obesity.

    PubMed

    Nogueiras, Ruben; Pérez-Tilve, Diego; Veyrat-Durebex, Christelle; Morgan, Donald A; Varela, Luis; Haynes, William G; Patterson, James T; Disse, Emmanuel; Pfluger, Paul T; López, Miguel; Woods, Stephen C; DiMarchi, Richard; Diéguez, Carlos; Rahmouni, Kamal; Rohner-Jeanrenaud, Françoise; Tschöp, Matthias H

    2009-05-06

    We investigated a possible role of the central glucagon-like peptide (GLP-1) receptor system as an essential brain circuit regulating adiposity through effects on nutrient partitioning and lipid metabolism independent from feeding behavior. Both lean and diet-induced obesity mice were used for our experiments. GLP-1 (7-36) amide was infused in the brain for 2 or 7 d. The expression of key enzymes involved in lipid metabolism was measured by real-time PCR or Western blot. To test the hypothesis that the sympathetic nervous system may be responsible for informing adipocytes about changes in CNS GLP-1 tone, we have performed direct recording of sympathetic nerve activity combined with experiments in genetically manipulated mice lacking beta-adrenergic receptors. Intracerebroventricular infusion of GLP-1 in mice directly and potently decreases lipid storage in white adipose tissue. These effects are independent from nutrient intake. Such CNS control of adipocyte metabolism was found to depend partially on a functional sympathetic nervous system. Furthermore, the effects of CNS GLP-1 on adipocyte metabolism were blunted in diet-induced obese mice. The CNS GLP-1 system decreases fat storage via direct modulation of adipocyte metabolism. This CNS GLP-1 control of adipocyte lipid metabolism appears to be mediated at least in part by the sympathetic nervous system and is independent of parallel changes in food intake and body weight. Importantly, the CNS GLP-1 system loses the capacity to modulate adipocyte metabolism in obese states, suggesting an obesity-induced adipocyte resistance to CNS GLP-1.

  10. Central GLP-1 receptor signalling accelerates plasma clearance of triacylglycerol and glucose by activating brown adipose tissue in mice.

    PubMed

    Kooijman, Sander; Wang, Yanan; Parlevliet, Edwin T; Boon, Mariëtte R; Edelschaap, David; Snaterse, Gido; Pijl, Hanno; Romijn, Johannes A; Rensen, Patrick C N

    2015-11-01

    Glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) agonism, used in the treatment of type 2 diabetes, has recently been shown to increase thermogenesis via the brain. As brown adipose tissue (BAT) produces heat by burning triacylglycerol (TG) and takes up glucose for de novo lipogenesis, the aim of this study was to evaluate the potential of chronic central GLP-1R activation by exendin-4 to facilitate clearance of lipids and glucose from the circulation by activating BAT. Lean and diet-induced obese (DIO) C57Bl/6J mice were used to explore the effect of a 5 day intracerebroventricular infusion of the GLP-1 analogue exendin-4 or vehicle on lipid and glucose uptake by BAT in both insulin-sensitive and insulin-resistant conditions. Central administration of exendin-4 in lean mice increased sympathetic outflow towards BAT and white adipose tissue (WAT), resulting in increased thermogenesis as evidenced by increased uncoupling protein 1 (UCP-1) protein levels and decreased lipid content, while the uptake of TG-derived fatty acids was increased in both BAT and WAT. Interestingly, in DIO mice, the effects on WAT were blunted, while exendin-4 still increased sympathetic outflow towards BAT and increased the uptake of plasma TG-derived fatty acids and glucose by BAT. These effects were accompanied by increased fat oxidation, lower plasma TG and glucose concentrations, and reduced body weight. Collectively, our results suggest that BAT activation may be a major contributor to the glucose- and TG-lowering effects of GLP-1R agonism.

  11. Inhibiting receptor for advanced glycation end product (AGE) and oxidative stress involved in the protective effect mediated by glucagon-like peptide-1 receptor on AGE induced neuronal apoptosis.

    PubMed

    Chen, Song; Yin, Lei; Xu, Zheng; An, Feng-Mao; Liu, Ai-Ran; Wang, Ying; Yao, Wen-Bing; Gao, Xiang-Dong

    2016-01-26

    Our previous study has demonstrated that glucagon-like peptide-1 (GLP-1) receptor agonist could protect neurons from advanced glycation end products (AGEs) toxicity in vitro. However, further studies are still needed to clarify the molecular mechanism of this GLP-1 receptor -dependent action. The present study mainly focused on the effect of GLP-1 receptor agonists against the receptor for advanced glycation end products (RAGE) signal pathway and the mechanism underlying this effect of GLP-1. Firstly the data based on the SH-GLP-1R(+) and SH-SY5Y cells confirmed our previous finding that GLP-1 receptor could mediate the protective effect against AGEs. The assays of the protein activity and of the mRNA level revealed that apoptosis-related proteins such as caspase-3, caspase-9, Bax and Bcl-2 were involved. Additionally, we found that both GLP-1 and exendin-4 could reduce AGEs-induced reactive oxygen species (ROS) accumulation by suppressing the activity of nicotinamide adenine dinucleotide phosphate-oxidase. Interestingly, we also found that GLP-1 receptor activation could attenuate the abnormal expression of the RAGE in vitro and in vivo. Furthermore, based on the analysis of the protein expression and translocation level of transcription factor nuclear factor-κB (NF-κB), and the use of GLP-1 receptor antagonist exendin(9-39) and NF-κB inhibitor pyrrolidine dithiocarbamate, we found that the effect mediated by GLP-1 receptor could alleviate the over expression of RAGE induced by ligand via the suppression of NF-κB. In summary, the results indicated that inhibiting RAGE/oxidative stress was involved in the protective effect of GLP-1 on neuron cells against AGEs induced apoptosis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. Refinement of glucagon-like peptide 1 docking to its intact receptor using mid-region photolabile probes and molecular modeling.

    PubMed

    Miller, Laurence J; Chen, Quan; Lam, Polo C-H; Pinon, Delia I; Sexton, Patrick M; Abagyan, Ruben; Dong, Maoqing

    2011-05-06

    The glucagon-like peptide 1 (GLP1) receptor is an important drug target within the B family of G protein-coupled receptors. Its natural agonist ligand, GLP1, has incretin-like actions and the receptor is a recognized target for management of type 2 diabetes mellitus. Despite recent solution of the structure of the amino terminus of the GLP1 receptor and several close family members, the molecular basis for GLP1 binding to and activation of the intact receptor remains unclear. We previously demonstrated molecular approximations between amino- and carboxyl-terminal residues of GLP1 and its receptor. In this work, we study spatial approximations with the mid-region of this peptide to gain insights into the orientation of the intact receptor and the ligand-receptor complex. We have prepared two new photolabile probes incorporating a p-benzoyl-l-phenylalanine into positions 16 and 20 of GLP1(7-36). Both probes bound to the GLP1 receptor specifically and with high affinity. These were each fully efficacious agonists, stimulating cAMP accumulation in receptor-bearing CHO cells in a concentration-dependent manner. Each probe specifically labeled a single receptor site. Protease cleavage and radiochemical sequencing identified receptor residue Leu(141) above transmembrane segment one as its site of labeling for the position 16 probe, whereas the position 20 probe labeled receptor residue Trp(297) within the second extracellular loop. Establishing ligand residue approximation with this loop region is unique among family members and may help to orient the receptor amino-terminal domain relative to its helical bundle region.

  13. Short bowel syndrome: influence of nutritional therapy and incretin GLP1 on bone marrow adipose tissue.

    PubMed

    Parreiras-E-Silva, Luciana T; de Araújo, Iana M; Elias, Jorge; Nogueira-Barbosa, Marcello H; Suen, Vivian M M; Marchini, Julio S; Bonella, Jéssica; Nahas, Andressa K; Salmon, Carlos E G; de Paula, Francisco J A

    2018-03-01

    Energy deprivation leads to a decrease in white adipose tissue and bone mineral density (BMD), while simultaneously inducing the expansion of marrow adipose tissue (MAT). In short bowel syndrome (SBS), parenteral nutrition mitigates the deterioration of nutritional status, including decreases in MAT. Osteoporosis is, however, a frequent complication of SBS. The objective of our study here was to evaluate the association of fat deposit sites (subcutaneous and visceral adipose tissues: intrahepatic lipid (IHL) and MAT) and the incretin glucagon-like peptide 1 (GLP1) with BMD in individuals with SBS. MAT was negatively correlated with lumbar spine BMD in normal individuals, but not in those in the SBS group, who otherwise showed a positive correlation between MAT and GLP1. In addition, in individuals with SBS, IHL was negatively associated with lumbar spine BMD and positively associated with C-terminal telopeptide of type 1 collagen (a serum biomarker of bone turnover). Caloric maintenance in individuals with SBS, therefore, seems to positively affect the relationship between MAT and BMD, which may be modulated, at least in part, by GLP1. © 2018 New York Academy of Sciences.

  14. Modulation of GLP-1 Levels by a Genetic Variant That Regulates the Cardiovascular Effects of Intensive Glycemic Control in ACCORD.

    PubMed

    Shah, Hetal S; Morieri, Mario Luca; Marcovina, Santica M; Sigal, Ronald J; Gerstein, Hertzel C; Wagner, Michael J; Motsinger-Reif, Alison A; Buse, John B; Kraft, Peter; Mychaleckyj, Josyf C; Doria, Alessandro

    2018-02-01

    A genome-wide association study in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial identified two markers (rs57922 and rs9299870) that were significantly associated with cardiovascular mortality during intensive glycemic control and could potentially be used, when combined into a genetic risk score (GRS), to identify patients with diabetes likely to derive benefit from intensive control rather than harm. The aim of this study was to gain insights into the pathways involved in the modulatory effect of these variants. Fasting levels of 65 biomarkers were measured at baseline and at 12 months of follow-up in the ACCORD-Memory in Diabetes (ACCORD-MIND) MRI substudy ( n = 562). Using linear regression models, we tested the association of the GRS with baseline and 12-month biomarker levels, and with their difference (Δ), among white subjects, with genotype data ( n = 351) stratified by intervention arm. A significant association was observed between GRS and ΔGLP-1 (glucagon-like peptide 1, active) in the intensive arm ( P = 3 × 10 -4 ). This effect was driven by rs57922 ( P = 5 × 10 -4 ). C/C homozygotes, who had been found to derive cardiovascular benefits from intensive treatment, showed a 22% increase in GLP-1 levels during follow-up. By contrast, T/T homozygotes, who had been found to experience increased cardiac mortality with intensive treatment, showed a 28% reduction in GLP-1 levels. No association between ΔGLP-1 and GRS or rs57922 was observed in the standard treatment arm. Differences in GLP-1 axis activation may mediate the modulatory effect of variant rs57922 on the cardiovascular response to intensive glycemic control. These findings highlight the importance of GLP-1 as a cardioprotective factor. © 2017 by the American Diabetes Association.

  15. The Effect of Exercise Intensity on Total PYY and GLP-1 in Healthy Females: A Pilot Study.

    PubMed

    Hallworth, Jillian R; Copeland, Jennifer L; Doan, Jon; Hazell, Tom J

    2017-01-01

    We compared the acute response of anorexigenic signals (total PYY and GLP-1) in response to submaximal and supramaximal exercise. Nine females completed three sessions: (1) moderate-intensity continuous training (MICT; 30 min; 65%  VO 2max ); (2) sprint interval training (SIT; 6 × 30 sec "all-out" cycling sprints with 4 min recovery); or (3) control (CTRL; no exercise). PYY and GLP-1 were measured via blood samples drawn before, immediately after, and 90 min after exercise. Perceptions of hunger were rated using a visual analogue scale at all blood sampling time points. There was a session × time interaction for GLP-1 ( p = 0.004) where SIT and MICT ( p < 0.015 and p < 0.001) were higher compared to CTRL both immediately and 90 min after exercise. There was a main effect of time for PYY where 90 min after exercise it was decreased versus before and immediately after exercise. There was a session × time interaction for hunger with lower ratings following SIT versus MICT ( p = 0.027) and CTRL ( p = 0.031) 90 min after exercise. These results suggest that though GLP-1 is elevated after exercise in women, it is not affected by exercise intensity though hunger was lower 90 min after exercise with SIT. As the sample size is small further study is needed to confirm these findings.

  16. Short-term administration of the GLP-1 analog liraglutide decreases circulating leptin and increases GIP levels and these changes are associated with alterations in CNS responses to food cues: A randomized, placebo-controlled, crossover study

    PubMed Central

    Farr, Olivia M.; Tsoukas, Michael A.; Triantafyllou, Georgios; Dincer, Fadime; Filippaios, Andreas; Ko, Byung-Joon; Mantzoros, Christos S.

    2016-01-01

    Background GLP-1 agonists, including liraglutide, have emerged as effective therapies for type 2 diabetes (DM) and obesity. Here, we attempted to delineate how liraglutide, at doses approved for DM, may impact circulating hormones influencing energy homeostasis in diabetics. Basic Procedures Using a randomized, placebo-controlled, double-blind, cross-over trial of 20 patients with type 2 diabetes, we examined the effects of liraglutide as compared to placebo on fasting levels of circulating hormones important to energy homeostasis, including leptin, ghrelin, PYY, and GIP. After 17 days (0.6 mg for 7 days, 1.2 mg for 7 days and 1.8 mg for 3 days) of treatment, we also studied changes in fMRI responses to food cues. Main Findings By design, to avoid any confounding by weight changes, subjects were studied for 17 days, i.e. before body weight changed. Participants on liraglutide had significantly increased GLP-1 levels (p<0.001), decreased percent change in leptin levels (p<0.01) and increased GIP levels (p<0.03) in comparison to placebo treated subjects. Whole brain regressions of functional activity in response to food cues reveal that increased GIP levels were associated with deactivation of the attention- and reward-related insula. Decreases in leptin levels were associated with activations in the reward-related midbrain, precuneus, and dorsolateral prefrontal cortex (DLPFC), and sensorimotor-related motor cortex and with deactivations in the attention-related parietal cortex and the cognitive control-related thalamus and pre-SMA. Principal Conclusions We demonstrate herein short-term changes to circulating levels of GIP and leptin in response to GLP-1 agonist liraglutide therapy. These findings suggest that liraglutide may alter the circulating levels of hormones important in energy homeostasis that, in turn, influence CNS perception of food cues. This could possibly lead to compensatory changes in energy homeostasis that would over time limit the efficacy of

  17. Characterization of glucagon-like peptide-1 receptor-binding determinants.

    PubMed

    Xiao, Q; Jeng, W; Wheeler, M B

    2000-12-01

    Glucagon-like peptide 1 (GLP-1) is a potent insulinotropic hormone currently under study as a therapeutic agent for type 2 diabetes. Since an understanding of the molecular mechanisms leading to high-affinity receptor (R) binding and activation may facilitate the development of more potent GLP-1R agonists, we have localized specific regions of GLP-1R required for binding. The purified N-terminal fragment (hereafter referred to as NT) of the GLP-1R produced in either insect (Sf9) or mammalian (COS-7) cells was shown to bind GLP-1. The physical interaction of NT with GLP-1 was first demonstrated by cross-linking ((125)I-GLP-1/NT complex band at approximately 28 kDa) and secondly by attachment to Ni(2+)-NTA beads. The GLP-1R NT protein attached to beads bound GLP-1, but with lower affinity (inhibitory concentration (IC(50)): 4.5 x 10(-7) M) than wild-type (WT) GLP-1R (IC(50): 5.2 x 10(-9)M). The low affinity of GLP-1R NT suggested that other receptor domains may contribute to GLP-1 binding. This was supported by studies using chimeric glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptors. GIP(1-151)/GLP-1R, but not GIP(1-222)/GLP-1R, exhibited specific GLP-1 binding and GLP-1-induced cAMP production, suggesting that the region encompassing transmembrane (TM) domain 1 through to TM3 was required for binding. Since it was hypothesized that certain charged or polar amino acids in this region might be involved in binding, these residues (TM2-TM3) were analyzed by substitution mutagenesis. Five mutants (K197A, D198A, K202A, D215A, R227A) displayed remarkably reduced binding affinity. These studies indicate that the NT domain of the GLP-1R is able to bind GLP-1, but charged residues concentrated at the distal TM2/extracellular loop-1 (EC1) interface (K197, D198, K202) and in EC1 (D215 and R227) probably contribute to the binding determinants of the GLP-1R.

  18. Involvement of histone methyltransferase GLP in HIV-1 latency through catalysis of H3K9 dimethylation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ding, Donglin; Qu, Xiying; Li, Lin

    Understanding the mechanism of HIV-1 latency is crucial to eradication of the viral reservoir in HIV-1-infected individuals. However, the role of histone methyltransferase (HMT) G9a-like protein (GLP) in HIV-1 latency is still unclear. In the present work, we established four clonal cell lines containing HIV-1 vector. We found that the integration sites of most clonal cell lines favored active gene regions. However, we also observed hypomethylation of CpG of HIV 5′LTR in all four clonal cell lines. Additionally, 5′-deoxy-5′-methylthioadenosine (MTA), a broad-spectrum histone methyltransferase inhibitor, was used to examine the role of histone methylation in HIV-1 latency. MTA was foundmore » to decrease the level of H3K9 dimethylation, causing reactivation of latent HIV-1 in C11 cells. GLP knockdown by small interfering RNA clearly induced HIV-1 LTR expression. Results suggest that GLP may play a significant role in the maintenance of HIV-1 latency by catalyzing dimethylation of H3K9. - Highlights: ► We have established an in vitro model of HIV-1 latency. ► The integration sites of most clonal cell lines favor in active gene regions. ► Hypomethylation occurs in CpG islands of HIV 5′LTR in all four clonal cell lines. ► MTA can reactivate latent HIV-1 by decreasing the level of H3K9 me2 in C11 cells. ► HMT GLP may play a significant role in the maintenance of HIV-1 latency.« less

  19. At the centennial of Michaelis and Menten, competing Michaelis-Menten steps explain effect of GLP-1 on blood-brain transfer and metabolism of glucose.

    PubMed

    Gejl, Michael; Rungby, Jørgen; Brock, Birgitte; Gjedde, Albert

    2014-08-01

    Glucagon-like peptide-1 (GLP-1) is a potent insulinotropic incretin hormone with both pancreatic and extrapancreatic effects. Studies of GLP-1 reveal significant effects in regions of brain tissue that regulate appetite and satiety. GLP-1 mimetics are used for the treatment of type 2 diabetes mellitus. GLP-1 interacts with peripheral functions in which the autonomic nervous system plays an important role, and emerging pre-clinical findings indicate a potential neuroprotective role of the peptide, for example in models of stroke and in neurodegenerative disorders. A century ago, Leonor Michaelis and Maud Menten described the steady-state enzyme kinetics that still apply to the multiple receptors, transporters and enzymes that define the biochemical reactions of the brain, including the glucose-dependent impact of GLP-1 on blood-brain glucose transfer and metabolism. This MiniReview examines the potential of GLP-1 as a molecule of interest for the understanding of brain energy metabolism and with reference to the impact on brain metabolism related to appetite and satiety regulation, stroke and neurodegenerative disorders. These effects can be understood only by reference to the original formulation of the Michaelis-Menten equation as applied to a chain of kinetically controlled steps. Indeed, the effects of GLP-1 receptor activation on blood-brain glucose transfer and brain metabolism of glucose depend on the glucose concentration and relative affinities of the steps both in vitro and in vivo, as in the pancreas. © 2014 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  20. New Basal Insulins: a Clinical Perspective of Their Use in the Treatment of Type 2 Diabetes and Novel Treatment Options Beyond Basal Insulin.

    PubMed

    Frias, Patrick F; Frias, Juan Pablo

    2017-08-18

    The purpose of this review was to review advances in basal insulin formulations and new treatment options for patients with type 2 diabetes not achieving glycemic targets despite optimized basal insulin therapy. Advances in basal insulin formulations have resulted in products with increasingly favorable pharmacokinetic and pharmacodynamic properties, including flatter, peakless action profiles, less inter- and intra-patient variability, and longer duration of activity. These properties have translated to significantly reduced risk of hypoglycemia (particularly during the night) compared with previous generation basal insulins. When optimized basal insulin therapy is not sufficient to obtain or maintain glycemic goals, various options exist to improve glycemic control, including intensification of insulin therapy with the addition of prandial insulin or changing to pre-mixed insulin and, more recently, the addition of a GLP-1 receptor agonist, either as a separate injection or as a component of one of the new fixed-ratio combinations of a basal insulin and GLP-1 RA. New safer and often more convenient basal insulins and fixed ratio combinations containing basal insulin (and GLP-1 receptor agonist) are available today for patients with type 2 diabetes not achieving glycemic goals. Head-to-head studies comparing the latest generation basal insulins are underway, and future studies assessing the fixed-ratio combinations will be important to better understand their differentiating features.

  1. LINC01121 Inhibits Cell Apoptosis While Facilitating Proliferation, Migration, and Invasion Though Negative Regulation of the Camp/PKA Signaling Pathway via GLP1R.

    PubMed

    Qian, Yi-Gang; Ye, Zhou; Chen, Hai-Yong; Lv, Zhen; Zhang, Ai-Bin; Fan, Le; Zhou, Jie; Zheng, Shu-Sen; Wang, Wei-Lin

    2018-05-24

    Pancreatic cancer is an aggressive malignancy as a result of highly metastatic potential. The current study was carried out to alter the expression of LINC01121 in pancreatic cancer, with the aim of elucidating its effects on the biological processes of cell proliferation, migration, invasion, and apoptosis. We hypothesized that both the GLP1R gene and cAMP/PKA signaling pathway participate in the aforementioned process. Microarray data (GSE14245, GSE27890 and GSE16515) and annotating probe files linked to pancreatic cancer were downloaded through the GEO database. The Multi Experiment Matrix (MEM) site was used to predict the target gene of lncRNA. Both pancreatic cancer tissues (n = 56) and paracancerous tissues (n = 45) were collected from patients diagnosed with pancreatic cancer. Immunohistochemistry was applied to identify the positive expression rate of GLP1R protein. Isolated pancreatic cancer cells and PANC-1 cells were independently classified into the blank, negative control (NC), LINC01121 vector, siRNA-LINC01121, siRNA-GLP1R and siRNA-LINC01121 + siRNA-GLP1R groups. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis were applied to detect the expressions of LINC01121, GLP1R, cAMP, PKA, CREB, Bcl-2, Bad and PCNA. Cell proliferation, migration, invasion, cycle progression, and apoptosis were examined by MTT assay, scratch test, Transwell assay and flow cytometry analyses of Annexin V-FITC/PI staining. Observations were made indicating that LINC01121 was highly expressed, while low expressions of GLP1R in pancreatic cancer were detected based on microarray data, which was largely in consistent with the data collected of LINC01121 and GLP1R within the tissues. The target prediction program and luciferase activity analysis was testament to the notion suggesting that GLP1R was indeed a target of LINC01121. In contrast to the blank and NC groups, the LINC01121 vector group exhibited increased expressions of LINC

  2. Central GLP-2 enhances hepatic insulin sensitivity via activating PI3K signaling in POMC neurons.

    PubMed

    Shi, Xuemei; Zhou, Fuguo; Li, Xiaojie; Chang, Benny; Li, Depei; Wang, Yi; Tong, Qingchun; Xu, Yong; Fukuda, Makoto; Zhao, Jean J; Li, Defa; Burrin, Douglas G; Chan, Lawrence; Guan, Xinfu

    2013-07-02

    Glucagon-like peptides (GLP-1/GLP-2) are coproduced and highlighted as key modulators to improve glucose homeostasis and insulin sensitivity after bariatric surgery. However, it is unknown if CNS GLP-2 plays any physiological role in the control of glucose homeostasis and insulin sensitivity. We show that mice lacking GLP-2 receptor (GLP-2R) in POMC neurons display glucose intolerance and hepatic insulin resistance. GLP-2R activation in POMC neurons is required for GLP-2 to enhance insulin-mediated suppression of hepatic glucose production (HGP) and gluconeogenesis. GLP-2 directly modulates excitability of POMC neurons in GLP-2R- and PI3K-dependent manners. GLP-2 initiates GLP-2R-p85α interaction and facilitates PI3K-Akt-dependent FoxO1 nuclear exclusion in POMC neurons. Central GLP-2 suppresses basal HGP and enhances insulin sensitivity, which are abolished in POMC-p110α KO mice. Thus, CNS GLP-2 plays a key physiological role in the control of HGP through activating PI3K-dependent modulation of membrane excitability and nuclear transcription of POMC neurons in the brain. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. EGO-1, a Putative RNA-Directed RNA Polymerase, Promotes Germline Proliferation in Parallel With GLP-1/Notch Signaling and Regulates the Spatial Organization of Nuclear Pore Complexes and Germline P Granules in Caenorhabditis elegans

    PubMed Central

    Vought, Valarie E.; Ohmachi, Mitsue; Lee, Min-Ho; Maine, Eleanor M.

    2005-01-01

    Caenorhabditis elegans EGO-1, a putative cellular RNA-directed RNA polymerase, promotes several aspects of germline development, including proliferation, meiosis, and gametogenesis, and ensures a robust response to RNA interference. In C. elegans, GLP-1/Notch signaling from the somatic gonad maintains a population of proliferating germ cells, while entry of germ cells into meiosis is triggered by the GLD-1 and GLD-2 pathways. GLP-1 signaling prevents germ cells from entering meiosis by inhibiting GLD-1 and GLD-2 activity. We originally identified the ego-1 gene on the basis of a genetic interaction with glp-1. Here, we investigate the role of ego-1 in germline proliferation. Our data indicate that EGO-1 does not positively regulate GLP-1 protein levels or GLP-1 signaling activity. Moreover, GLP-1 signaling does not positively regulate EGO-1 activity. EGO-1 does not inhibit expression of GLD-1 protein in the distal germline. Instead, EGO-1 acts in parallel with GLP-1 signaling to influence the proliferation vs. meiosis fate choice. Moreover, EGO-1 and GLD-1 act in parallel to ensure germline health. Finally, the size and distribution of nuclear pore complexes and perinuclear P granules are altered in the absence of EGO-1, effects that disrupt germ cell biology per se and probably limit germline growth. PMID:15911573

  4. Cardiovascular outcomes associated with canagliflozin versus other non-gliflozin antidiabetic drugs: population based cohort study.

    PubMed

    Patorno, Elisabetta; Goldfine, Allison B; Schneeweiss, Sebastian; Everett, Brendan M; Glynn, Robert J; Liu, Jun; Kim, Seoyoung C

    2018-02-06

    To evaluate the cardiovascular safety of canagliflozin, a sodium-glucose cotransporter 2 inhibitor for the treatment of type 2 diabetes mellitus, in direct comparisons with DPP-4 inhibitors (DPP-4i), GLP-1 receptor agonists (GLP-1RA), or sulfonylureas, as used in routine practice. Population based retrospective cohort study. Nationwide sample of patients with type 2 diabetes from a large de-identified US commercial healthcare database (Optum Clinformatics Datamart). Three pairwise 1:1 propensity score matched cohorts of patients with type 2 diabetes 18 years and older who initiated canagliflozin or a comparator non-gliflozin antidiabetic agent (ie, a DPP-4i, a GLP-1RA, or a sulfonylurea) between April 2013 and September 2015. The primary outcomes were heart failure admission to hospital and a composite cardiovascular endpoint (comprised of being admitted to hospital for acute myocardial infarction, ischemic stroke, or hemorrhagic stroke). Hazard ratios and 95% confidence intervals were estimated in each propensity score matched cohort controlling for more than 100 baseline characteristics. During a 30 month period, the hazard ratio for heart failure admission to hospital associated with canagliflozin was 0.70 (95% confidence interval 0.54 to 0.92) versus a DPP-4i (n=17 667 pairs), 0.61 (0.47 to 0.78) versus a GLP-1RA (20 539), and 0.51 (0.38 to 0.67) versus a sulfonylurea (17 354 ). The hazard ratio for the composite cardiovascular endpoint associated with canagliflozin was 0.89 (0.68 to 1.17) versus a DPP-4i, 1.03 (0.79 to 1.35) versus a GLP-1RA, and 0.86 (0.65 to 1.13) versus a sulfonylurea. Results were similar in sensitivity analyses further adjusting for baseline hemoglobin A1c levels and in subgroups of patients with and without prior cardiovascular disease or heart failure. In this large cohort study, canagliflozin was associated with a lower risk of heart failure admission to hospital and with a similar risk of myocardial infarction or stroke in

  5. Crystal structure of the ligand-bound glucagon-like peptide-1 receptor extracellular domain.

    PubMed

    Runge, Steffen; Thøgersen, Henning; Madsen, Kjeld; Lau, Jesper; Rudolph, Rainer

    2008-04-25

    The glucagon-like peptide-1 receptor (GLP-1R) belongs to Family B1 of the seven-transmembrane G protein-coupled receptors, and its natural agonist ligand is the peptide hormone glucagon-like peptide-1 (GLP-1). GLP-1 is involved in glucose homeostasis, and activation of GLP-1R in the plasma membrane of pancreatic beta-cells potentiates glucose-dependent insulin secretion. The N-terminal extracellular domain (nGLP-1R) is an important ligand binding domain that binds GLP-1 and the homologous peptide Exendin-4 with differential affinity. Exendin-4 has a C-terminal extension of nine amino acid residues known as the "Trp cage", which is absent in GLP-1. The Trp cage was believed to interact with nGLP-1R and thereby explain the superior affinity of Exendin-4. However, the molecular details that govern ligand binding and specificity of nGLP-1R remain undefined. Here we report the crystal structure of human nGLP-1R in complex with the antagonist Exendin-4(9-39) solved by the multiwavelength anomalous dispersion method to 2.2A resolution. The structure reveals that Exendin-4(9-39) is an amphipathic alpha-helix forming both hydrophobic and hydrophilic interactions with nGLP-1R. The Trp cage of Exendin-4 is not involved in binding to nGLP-1R. The hydrophobic binding site of nGLP-1R is defined by discontinuous segments including primarily a well defined alpha-helix in the N terminus of nGLP-1R and a loop between two antiparallel beta-strands. The structure provides for the first time detailed molecular insight into ligand binding of the human GLP-1 receptor, an established target for treatment of type 2 diabetes.

  6. Central GLP-2 enhances hepatic insulin sensitivity via activating PI3K signaling in POMC neurons

    PubMed Central

    Shi, Xuemei; Zhou, Fuguo; Li, Xiaojie; Chang, Benny; Li, Depei; Wang, Yi; Tong, Qingchun; Xu, Yong; Fukuda, Makoto; Zhao, Jean J.; Li, Defa; Burrin, Douglas G.; Chan, Lawrence; Guan, Xinfu

    2013-01-01

    Glucagon-like peptides (GLP-1/2) are co-produced and highlighted as key modulators to improve glucose homeostasis and insulin sensitivity after bariatric surgery. However, it is unknown if CNS GLP-2 plays any physiological role in the control of glucose homeostasis and insulin sensitivity. We show that mice lacking GLP-2 receptor (GLP-2R) in POMC neurons display glucose intolerance and hepatic insulin resistance. GLP-2R activation in POMC neurons is required for GLP-2 to enhance insulin-mediated suppression of hepatic glucose production (HGP) and gluconeogenesis. GLP-2 directly modulates excitability of POMC neurons in GLP-2R- and PI3K-dependent manners. GLP-2 initiates GLP-2R-p85α interaction and facilitates PI3K-Akt-dependent FoxO1 nuclear exclusion in POMC neurons. Central GLP-2 suppresses basal HGP and enhances insulin sensitivity, which are abolished in POMC-p110α KO mice. Thus, CNS GLP-2 plays a key physiological role in the control of hepatic glucose production through activating PI3K-dependent modulation of membrane excitability and nuclear transcription of POMC neurons in the brain. PMID:23823479

  7. Acute activation of GLP-1-expressing neurons promotes glucose homeostasis and insulin sensitivity

    USDA-ARS?s Scientific Manuscript database

    Glucagon-like peptides are co-released from enteroendocrine L cells in the gut and preproglucagon (PPG) neurons in the Brainstem. PPG-derived GLP-1/2 are probably key neuroendocrine signals for the control of energy balance and glucose Homeostasis. The objective of this study was to determine whethe...

  8. Effects of incretin agonists on endothelial nitric oxide synthase expression and nitric oxide synthesis in human coronary artery endothelial cells exposed to TNFα and glycated albumin.

    PubMed

    Garczorz, Wojciech; Francuz, Tomasz; Siemianowicz, Krzysztof; Kosowska, Agnieszka; Kłych, Agnieszka; Aghdam, Mohammad Reza F; Jagoda, Krystyna

    2015-02-01

    There have been a number of beneficial effects of incretin agonists on the cardiovascular system. Glycated albumin (GA) and tumor necrosis factor (TNFα) may lead to endothelial dysfunction. Due to reports of cardioprotective effects of incretin agonist, we wanted to determine if GLP-1 and exendin-4 can reverse diminished production of nitric oxide (NO) after treatment with TNFα and GA. The objective of our experiment was to study the interaction between incretin agonists and proinflammatory substances like TNFα and GA on production of NO in HCAEC. Human vascular endothelial cells from the coronary artery (HCAEC) were used. The mRNA expression and protein level of endothelial nitric oxide synthase (eNOS) and inducible (iNOS) were quantified. NO production was measured in cells using DAF-FM/DA and flow cytometry. TNFα (10 ng/mL) decreased eNOS: mRNA by 90% and protein level by 31%. TNFα also decreased NO by 33%. GA (500 μg/mL) neither affected eNOS expression nor the protein level, but inhibited nearly all formation of NO in endothelium. GLP-1 (100 nM) and exendin-4 (1 and 10nM) decreased the amount of NO compared to control. Incubation of HCAEC with TNFα and incretin agonists did not change or moderately reduce the amount of NO compared to TNFα alone. TNFα and GA decrease production of NO in HCAEC, presumably by inducing reactive oxygen species or eNOS uncoupling. Incretin agonists in tested concentrations in the presence of l-arginine were not able to reverse this effect and instead led to a further reduction in NO production. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  9. The effects of fiber enrichment of pasta and fat content on gastric emptying, GLP-1, glucose, and insulin responses to a meal.

    PubMed

    Frost, G S; Brynes, A E; Dhillo, W S; Bloom, S R; McBurney, M I

    2003-02-01

    To assess whether the addition of viscous fiber at an amount recommended by the US FDA to allow a 'low saturated fat, cholesterol, soluble fiber and coronary heart disease', health claim label on a food package (1.7 g psyllium) and/or fat (30 g sunflower oil and 3 g sodium propionate) to a pasta meal would affect gastric emptying, postprandial glucose, insulin and GLP-1 concentrations. Ten subjects participated in a two-by-two single blind randomized crossover study. Four meals containing 50 g of available carbohydrate were consumed: pasta with or without psyllium enrichment served with a tomato sauce with (520 kcal per meal) and without (240 kcal per meal) fat. Blood samples were taken for 240 min following the meal and all subjects consumed a buffet meal at the end of the study. Gastric emptying was measured using the paracetamol absorption test. Blood was analysed for glucose, insulin, GLP-1. Visual analog scales were used to record feelings of hunger, pleasantness and nausea. The psyllium-enriched pasta had no significant effect on gastric emptying or the incremental area under the curve (IAUC) for GLP-1, insulin or glucose compared with the control pasta. The addition of polyunsaturated fat and sodium propionate significantly increased the IAUC for GLP-1 (P<0.001), delaying gastric emptying (P<0.002), and decreasing glucose (P<0.002). A dose of 1.7 g psyllium did not evoke measurable effects on gastric emptying, postprandial GLP-1, insulin or glucose metabolism. However the addition of 30 g of oil and 3 g of sodium propionate to the pasta did reduce gastric emptying, increase GLP-1 and reduce glucose and insulin concentrations. While this short-term study may have implications in terms of reducing the risk of diabetes and improving coronary risk factor profiles the long term effects of these nutrients need to be studied.

  10. Synergism by individual macronutrients explains the marked early GLP-1 and islet hormone responses to mixed meal challenge in mice.

    PubMed

    Ahlkvist, L; Vikman, J; Pacini, G; Ahrén, B

    2012-10-10

    Apart from glucose, proteins and lipids also stimulate incretin and islet hormone secretion. However, the glucoregulatory effect of macronutrients in combination is poorly understood. We therefore developed an oral mixed meal model in mice to 1) explore the glucagon-like peptide-1 (GLP-1) and islet hormone responses to mixed meal versus isocaloric glucose, and 2) characterize the relative contribution of individual macronutrients to these responses. Anesthetized C57BL/6J female mice were orally gavaged with 1) a mixed meal (0.285 kcal; glucose, whey protein and peanut oil; 60/20/20% kcal) versus an isocaloric glucose load (0.285 kcal), and 2) a mixed meal (0.285 kcal) versus glucose, whey protein or peanut oil administered individually in their mixed meal caloric quantity, i.e., 0.171, 0.055 and 0.055 kcal, respectively. Plasma was analyzed for glucose, insulin and intact GLP-1 before and during oral challenges. Plasma glucose was lower after mixed meal versus after isocaloric glucose ingestion. In spite of this, the peak insulin response (P=0.02), the peak intact GLP-1 levels (P=0.006) and the estimated β-cell function (P=0.005) were higher. Furthermore, the peak insulin (P=0.004) and intact GLP-1 (P=0.006) levels were higher after mixed meal ingestion than the sum of responses to individual macronutrients. Compared to glucose alone, we conclude that there is a marked early insulin response to mixed meal ingestion, which emanates from a synergistic, rather than an additive, effect of the individual macronutrients in the mixed meal and is in part likely caused by increased levels of GLP-1. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Incretin-Based Therapies for Diabetic Complications: Basic Mechanisms and Clinical Evidence

    PubMed Central

    Kawanami, Daiji; Matoba, Keiichiro; Sango, Kazunori; Utsunomiya, Kazunori

    2016-01-01

    An increase in the rates of morbidity and mortality associated with diabetic complications is a global concern. Glycemic control is important to prevent the development and progression of diabetic complications. Various classes of anti-diabetic agents are currently available, and their pleiotropic effects on diabetic complications have been investigated. Incretin-based therapies such as dipeptidyl peptidase (DPP)-4 inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1RA) are now widely used in the treatment of patients with type 2 diabetes. A series of experimental studies showed that incretin-based therapies have beneficial effects on diabetic complications, independent of their glucose-lowering abilities, which are mediated by anti-inflammatory and anti-oxidative stress properties. Based on these findings, clinical studies to assess the effects of DPP-4 inhibitors and GLP-1RA on diabetic microvascular and macrovascular complications have been performed. Several but not all studies have provided evidence to support the beneficial effects of incretin-based therapies on diabetic complications in patients with type 2 diabetes. We herein discuss the experimental and clinical evidence of incretin-based therapy for diabetic complications. PMID:27483245

  12. Glucagon-like peptide-1 receptor expression on human eosinophils and its regulation of eosinophil activation.

    PubMed

    Mitchell, P D; Salter, B M; Oliveria, J P; El-Gammal, A; Tworek, D; Smith, S G; Sehmi, R; Gauvreau, G M; Butler, M; O'Byrne, P M

    2017-03-01

    Glucagon-like peptide-1 (GLP-1) and its receptor are part of the incretin family of hormones that regulate glucose metabolism. GLP-1 also has immune modulatory roles. To measure the expression of the GLP-1 receptor (GLP-1R) on eosinophils and neutrophils in normal and asthmatic subjects and evaluate effects of a GLP-1 analog on eosinophil function. Peripheral blood samples were taken from 10 normal and 10 allergic asthmatic subjects. GLP-1R expression was measured on eosinophils and neutrophils. Subsequently, the asthmatic subjects underwent allergen and diluent inhalation challenges, and GLP-1R expression was measured. Purified eosinophils, collected from mild asthmatic subjects, were stimulated with lipopolysaccharide (LPS) and a GLP-1 analog to evaluate eosinophil cell activation markers CD11b and CD69 and cytokine (IL-4, IL-5, IL-8 and IL-13) production. Glucagon-like peptide-1 receptor is expressed on human eosinophils and neutrophils. Eosinophil, but not neutrophil, expression of GLP-1R is significantly higher in normal controls compared to allergic asthmatics. The expression of GLP-1R did not change on either eosinophils or neutrophils following allergen challenge. A GLP-1 analog significantly decreased the expression of eosinophil-surface activation markers following LPS stimulation and decreased eosinophil production of IL-4, IL-8 and IL-13, but not IL-5. Glucagon-like peptide-1 receptor is expressed on human eosinophils and neutrophils. A GLP-1 analog attenuates LPS-stimulated eosinophil activation. GLP-1 agonists may have additional adjunctive indications in treating persons with concomitant type 2 diabetes mellitus and asthma. © 2016 John Wiley & Sons Ltd.

  13. Direct effects of glucose, insulin, GLP-1, and GIP on bulbospinal neurons in the rostral ventrolateral medulla in neonatal wistar rats.

    PubMed

    Oshima, Naoki; Onimaru, Hiroshi; Matsubara, Hidehito; Uchida, Takahiro; Watanabe, Atsushi; Imakiire, Toshihiko; Nishida, Yasuhiro; Kumagai, Hiroo

    2017-03-06

    Although patients with diabetes mellitus (DM) often exhibit hypertension, the mechanisms responsible for this correlation are not well known. We hypothesized that the bulbospinal neurons in the rostral ventrolateral medulla (RVLM) are affected by the levels of glucose, insulin, or incretins (glucagon like peptide-1 [GLP-1] or glucose-dependent insulinotropic peptide [GIP]) in patients with DM. To investigate whether RVLM neurons are activated by glucose, insulin, GLP-1, or GIP, we examined changes in the membrane potentials of bulbospinal RVLM neurons using whole-cell patch-clamp technique during superfusion with various levels of glucose or these hormones in neonatal Wistar rats. A brainstem-spinal cord preparation was used for the experiments. A low level of glucose stimulated bulbospinal RVLM neurons. During insulin superfusion, almost all the RVLM neurons were depolarized, while during GLP-1 or GIP superfusion, almost all the RVLM neurons were hyperpolarized. Next, histological examinations were performed to examine transporters for glucose and receptors for insulin, GLP-1, and GIP on RVLM neurons. Low-level glucose-depolarized RVLM neurons exhibited the presence of glucose transporter 3 (GLUT3). Meanwhile, insulin-depolarized, GLP-1-hyperpolarized, and GIP-hyperpolarized RVLM neurons showed each of the respective specific receptor. These results indicate that a low level of glucose stimulates bulbospinal RVLM neurons via specific transporters on these neurons, inducing hypertension. Furthermore, an increase in insulin or a reduction in incretins may also activate the sympathetic nervous system and induce hypertension by activating RVLM neurons via their own receptors. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  14. Multiple regulatory elements for the glpA operon encoding anaerobic glycerol-3-phosphate dehydrogenase and the glpD operon encoding aerobic glycerol-3-phosphate dehydrogenase in Escherichia coli: further characterization of respiratory control.

    PubMed

    Iuchi, S; Cole, S T; Lin, E C

    1990-01-01

    In Escherichia coli, sn-glycerol-3-phosphate can be oxidized by two different flavo-dehydrogenases, an anaerobic enzyme encoded by the glpACB operon and an aerobic enzyme encoded by the glpD operon. These two operons belong to the glp regulon specifying the utilization of glycerol, sn-glycerol-3-phosphate, and glycerophosphodiesters. In glpR mutant cells grown under conditions of low catabolite repression, the glpA operon is best expressed anaerobically with fumarate as the exogenous electron acceptor, whereas the glpD operon is best expressed aerobically. Increased anaerobic expression of glpA is dependent on the fnr product, a pleiotropic activator of genes involved in anaerobic respiration. In this study we found that the expression of a glpA1(Oxr) (oxygen-resistant) mutant operon, selected for increased aerobic expression, became less dependent on the FNR protein but more dependent on the cyclic AMP-catabolite gene activator protein complex mediating catabolite repression. Despite the increased aerobic expression of glpA1(Oxr), a twofold aerobic repressibility persisted. Moreover, anaerobic repression by nitrate respiration remained normal. Thus, there seems to exist a redox control apart from the FNR-mediated one. We also showed that the anaerobic repression of the glpD operon was fully relieved by mutations in either arcA (encoding a presumptive DNA recognition protein) or arcB (encoding a presumptive redox sensor protein). The arc system is known to mediate pleiotropic control of genes of aerobic function.

  15. cAMP-secretion coupling is impaired in diabetic GK/Par rat β-cells: a defect counteracted by GLP-1.

    PubMed

    Dolz, Manuel; Movassat, Jamileh; Bailbé, Danielle; Le Stunff, Hervé; Giroix, Marie-Hélène; Fradet, Magali; Kergoat, Micheline; Portha, Bernard

    2011-11-01

    cAMP-raising agents with glucagon-like peptide-1 (GLP-1) as the first in class, exhibit multiple actions that are beneficial for the treatment of type 2 diabetic (T2D) patients, including improvement of glucose-induced insulin secretion (GIIS). To gain additional insight into the role of cAMP in the disturbed stimulus-secretion coupling within the diabetic β-cell, we examined more thoroughly the relationship between changes in islet cAMP concentration and insulin release in the GK/Par rat model of T2D. Basal cAMP content in GK/Par islets was significantly higher, whereas their basal insulin release was not significantly different from that of Wistar (W) islets. Even in the presence of IBMX or GLP-1, their insulin release did not significantly change despite further enhanced cAMP accumulation in both cases. The high basal cAMP level most likely reflects an increased cAMP generation in GK/Par compared with W islets since 1) forskolin dose-dependently induced an exaggerated cAMP accumulation; 2) adenylyl cyclase (AC)2, AC3, and G(s)α proteins were overexpressed; 3) IBMX-activated cAMP accumulation was less efficient and PDE-3B and PDE-1C mRNA were decreased. Moreover, the GK/Par insulin release apparatus appears less sensitive to cAMP, since GK/Par islets released less insulin at submaximal cAMP levels and required five times more cAMP to reach a maximal secretion rate no longer different from W. GLP-1 was able to reactivate GK/Par insulin secretion so that GIIS became indistinguishable from that of W. The exaggerated cAMP production is instrumental, since GLP-1-induced GIIS reactivation was lost in the presence the AC blocker 2',5'-dideoxyadenosine. This GLP-1 effect takes place in the absence of any improvement of the [Ca(2+)](i) response and correlates with activation of the cAMP-dependent PKA-dependent pathway.

  16. Rational Design of Dual Agonist-Antibody Fusions as Long-acting Therapeutic Hormones.

    PubMed

    Liu, Yan; Wang, Ying; Zhang, Yong; Liu, Tao; Jia, Haiqun; Zou, Huafei; Fu, Qiangwei; Zhang, Yuhan; Lu, Lucy; Chao, Elizabeth; Parker, Holly; Nguyen-Tran, Van; Shen, Weijun; Wang, Danling; Schultz, Peter G; Wang, Feng

    2016-11-18

    Recent studies have suggested that modulation of two or more signaling pathways can achieve substantial weight loss and glycemic stability. We have developed an approach to the generation of bifunctional antibody agonists that activate leptin receptor and GLP-1 receptor. Leptin was fused into the complementarity determining region 3 loop of the light chain alone, or in combination with exendin-4 (EX4) fused at the N-terminus of the heavy chain of Herceptin. The antibody fusions exhibit similar or increased in vitro activities on their cognate receptors, but 50-100-fold longer circulating half-lives in rodents compared to the corresponding native peptides/proteins. The efficacy of the leptin/EX4 dual antibody fusion on weight loss, especially fat mass loss, was enhanced in ob/ob mice and DIO mice compared to the antibody fusion of either EX4 or leptin alone. This work demonstrates the versatility of this combinatorial fusion strategy for generating dual antibody agonists with long half-lives.

  17. In vivo dual-delivery of glucagon like peptide-1 (GLP-1) and dipeptidyl peptidase-4 (DPP4) inhibitor through composites prepared by microfluidics for diabetes therapy

    NASA Astrophysics Data System (ADS)

    Araújo, F.; Shrestha, N.; Gomes, M. J.; Herranz-Blanco, B.; Liu, D.; Hirvonen, J. J.; Granja, P. L.; Santos, H. A.; Sarmento, B.

    2016-05-01

    Oral delivery of proteins is still a challenge in the pharmaceutical field. Nanoparticles are among the most promising carrier systems for the oral delivery of proteins by increasing their oral bioavailability. However, most of the existent data regarding nanosystems for oral protein delivery is from in vitro studies, lacking in vivo experiments to evaluate the efficacy of these systems. Herein, a multifunctional composite system, tailored by droplet microfluidics, was used for dual delivery of glucagon like peptide-1 (GLP-1) and dipeptidyl peptidase-4 inhibitor (iDPP4) in vivo. Oral delivery of GLP-1 with nano- or micro-systems has been studied before, but the simultaneous nanodelivery of GLP-1 with iDPP4 is a novel strategy presented here. The type 2 diabetes mellitus (T2DM) rat model, induced through the combined administration of streptozotocin and nicotinamide, a non-obese model of T2DM, was used. The combination of both drugs resulted in an increase in the hypoglycemic effects in a sustained, but prolonged manner, where the iDPP4 improved the therapeutic efficacy of GLP-1. Four hours after the oral administration of the system, blood glucose levels were decreased by 44%, and were constant for another 4 h, representing half of the glucose area under the curve when compared to the control. An enhancement of the plasmatic insulin levels was also observed 6 h after the oral administration of the dual-drug composite system and, although no statistically significant differences existed, the amount of pancreatic insulin was also higher. These are promising results for the oral delivery of GLP-1 to be pursued further in a chronic diabetic model study.

  18. The glycerol-dependent metabolic persistence of Pseudomonas putida KT2440 reflects the regulatory logic of the GlpR repressor.

    PubMed

    Nikel, Pablo I; Romero-Campero, Francisco J; Zeidman, Joshua A; Goñi-Moreno, Ángel; de Lorenzo, Víctor

    2015-03-31

    The growth of the soil bacterium Pseudomonas putida KT2440 on glycerol as the sole carbon source is characterized by a prolonged lag phase, not observed with other carbon substrates. We examined the bacterial growth in glycerol cultures while monitoring the metabolic activity of individual cells. Fluorescence microscopy and flow cytometry, as well as the analysis of the temporal start of growth in single-cell cultures, revealed that adoption of a glycerol-metabolizing regime was not the result of a gradual change in the whole population but rather reflected a time-dependent bimodal switch between metabolically inactive (i.e., nongrowing) and fully active (i.e., growing) bacteria. A transcriptional Φ(glpD-gfp) fusion (a proxy of the glycerol-3-phosphate [G3P] dehydrogenase activity) linked the macroscopic phenotype to the expression of the glp genes. Either deleting glpR (encoding the G3P-responsive transcriptional repressor that controls the expression of the glpFKRD gene cluster) or altering G3P formation (by overexpressing glpK, encoding glycerol kinase) abolished the bimodal glpD expression. These manipulations eliminated the stochastic growth start by shortening the otherwise long lag phase. Provision of glpR in trans restored the phenotypes lost in the ΔglpR mutant. The prolonged nongrowth regime of P. putida on glycerol could thus be traced to the regulatory device controlling the transcription of the glp genes. Since the physiological agonist of GlpR is G3P, the arrangement of metabolic and regulatory components at this checkpoint merges a positive feedback loop with a nonlinear transcriptional response, a layout fostering the observed time-dependent shift between two alternative physiological states. Phenotypic variation is a widespread attribute of prokaryotes that leads, inter alia, to the emergence of persistent bacteria, i.e., live but nongrowing members within a genetically clonal population. Persistence allows a fraction of cells to avoid the

  19. Equivalent Increases in Circulating GLP-1 Following Jejunal Delivery of Intact and Hydrolysed Casein: Relevance to Satiety Induction Following Bariatric Surgery.

    PubMed

    le Roux, Carel W; Engström, My; Björnfot, Niclas; Fändriks, Lars; Docherty, Neil G

    2016-08-01

    Both Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) decrease the latency of food delivery to the proximal small intestine. This is implicated in exaggerated post-prandial release of glucagon-like peptide 1 (GLP-1), which provokes early satiety and reductions in food intake. Altered stomach anatomy also creates a deficit in enzymatic pre-processing. The impact of this state effect as a modulator of gut hormone responses remains underexplored. A double-blind cross-over trial study was conducted in 13 healthy subjects assigned to receive in the fasted state and in random order at 1 week apart, a direct jejunal infusion of either intact casein or a casein hydrolysate. Downstream effects on GLP-1 release, ratings of hunger and fullness and food and water intake on each study day were recorded when an ad libitum meal was provided 30 min after the infusion. Circulating GLP-1 was increased 25 min after infusions and peaked to a similar degree at 15 min post-meal initiation. The hormone surge had no impact on ratings of hunger and fullness ahead of the ad libitum meal. The kinetic and magnitude of satiation following each infusion was not significantly different. Food and water intake were likewise not differentially impacted by the two infusion types. Protein macronutrient state upon arrival in the small intestine does not in isolation impact upon GLP-1 responses and subsequent onset of satiety. This potentially points to rate of delivery being the dominant factor in exaggerated post-prandial GLP-1 responses in patients post-RYGB and VSG.

  20. Improvement of L-phenylalanine production from glycerol by recombinant Escherichia coli strains: the role of extra copies of glpK, glpX, and tktA genes.

    PubMed

    Gottlieb, Katrin; Albermann, Christoph; Sprenger, Georg A

    2014-07-11

    For the production of L-phenylalanine (L-Phe), two molecules of phosphoenolpyruvate (PEP) and one molecule erythrose-4-phosphate (E4P) are necessary. PEP stems from glycolysis whereas E4P is formed in the pentose phosphate pathway (PPP). Glucose, commonly used for L-Phe production with recombinant E. coli, is taken up via the PEP-dependent phosphotransferase system which delivers glucose-6-phosphate (G6P). G6P enters either glycolysis or the PPP. In contrast, glycerol is phosphorylated by an ATP-dependent glycerol kinase (GlpK) thus saving one PEP. However, two gluconeogenic reactions (fructose-1,6-bisphosphate aldolase, fructose-1,6-bisphosphatase, FBPase) are necessary for growth and provision of E4P. Glycerol has become an important carbon source for biotechnology and reports on production of L-Phe from glycerol are available. However, the influence of FBPase and transketolase reactions on L-Phe production has not been reported. L-Phe productivity of parent strain FUS4/pF81 (plasmid-encoded genes for aroF, aroB, aroL, pheA) was compared on glucose and glycerol as C sources. On glucose, a maximal carbon recovery of 0.19 mM C(Phe)/C(Glucose) and a maximal space-time-yield (STY) of 0.13 g l(-1) h(-1) was found. With glycerol, the maximal carbon recovery was nearly the same (0.18 mM C(Phe)/C(Glycerol)), but the maximal STY was higher (0.21 g l(-1) h(-1)). We raised the chromosomal gene copy number of the genes glpK (encoding glycerol kinase), tktA (encoding transketolase), and glpX (encoding fructose-1,6-bisphosphatase) individually. Overexpression of glpK (or its feedback-resistant variant, glpK(G232D)) had little effect on growth rate; L-Phe production was about 30% lower than in FUS4/pF81. Whereas the overexpression of either glpX or tktA had minor effects on productivity (0.20 mM C(Phe)/C(Glycerol); 0.25 g l(-1) h(-1) and 0.21 mM C(Phe)/C(Glycerol); 0.23 g l(-1) h(-1), respectively), the combination of extra genes of glpX and tktA together led to an increase in

  1. Improvement of L-phenylalanine production from glycerol by recombinant Escherichia coli strains: The role of extra copies of glpK, glpX, and tktA genes

    PubMed Central

    2014-01-01

    Background For the production of L-phenylalanine (L-Phe), two molecules of phosphoenolpyruvate (PEP) and one molecule erythrose-4-phosphate (E4P) are necessary. PEP stems from glycolysis whereas E4P is formed in the pentose phosphate pathway (PPP). Glucose, commonly used for L-Phe production with recombinant E. coli, is taken up via the PEP-dependent phosphotransferase system which delivers glucose-6-phosphate (G6P). G6P enters either glycolysis or the PPP. In contrast, glycerol is phosphorylated by an ATP-dependent glycerol kinase (GlpK) thus saving one PEP. However, two gluconeogenic reactions (fructose-1,6-bisphosphate aldolase, fructose-1,6-bisphosphatase, FBPase) are necessary for growth and provision of E4P. Glycerol has become an important carbon source for biotechnology and reports on production of L-Phe from glycerol are available. However, the influence of FBPase and transketolase reactions on L-Phe production has not been reported. Results L-Phe productivity of parent strain FUS4/pF81 (plasmid-encoded genes for aroF, aroB, aroL, pheA) was compared on glucose and glycerol as C sources. On glucose, a maximal carbon recovery of 0.19 mM CPhe/CGlucose and a maximal space-time-yield (STY) of 0.13 g l−1 h−1 was found. With glycerol, the maximal carbon recovery was nearly the same (0.18 mM CPhe/CGlycerol), but the maximal STY was higher (0.21 g l−1 h−1). We raised the chromosomal gene copy number of the genes glpK (encoding glycerol kinase), tktA (encoding transketolase), and glpX (encoding fructose-1,6-bisphosphatase) individually. Overexpression of glpK (or its feedback-resistant variant, glpKG232D) had little effect on growth rate; L-Phe production was about 30% lower than in FUS4/pF81. Whereas the overexpression of either glpX or tktA had minor effects on productivity (0.20 mM CPhe/CGlycerol; 0.25 g l−1 h−1 and 0.21 mM CPhe/CGlycerol; 0.23 g l−1 h−1, respectively), the combination of extra genes of glpX and tktA together led

  2. Serodiagnosis of Louse-Borne Relapsing Fever with Glycerophosphodiester Phosphodiesterase (GlpQ) from Borrelia recurrentis

    PubMed Central

    Porcella, Stephen F.; Raffel, Sandra J.; Schrumpf, Merry E.; Schriefer, Martin E.; Dennis, David T.; Schwan, Tom G.

    2000-01-01

    Human louse-borne relapsing fever occurs in sporadic outbreaks in central and eastern Africa that are characterized by significant morbidity and mortality. Isolates of the causative agent, Borrelia recurrentis, were obtained from the blood of four patients during a recent epidemic of the disease in southern Sudan. The glpQ gene, encoding glycerophosphodiester phosphodiesterase, from these isolates was sequenced and compared with the glpQ sequences obtained from other relapsing-fever spirochetes. Previously we showed that GlpQ of Borrelia hermsii is an immunogenic protein with utility as a serological test antigen for discriminating tick-borne relapsing fever from Lyme disease. In the present work, we cloned and expressed the glpQ gene from B. recurrentis and used recombinant GlpQ in serological tests. Acute- and convalescent-phase serum samples obtained from 42 patients with louse-borne relapsing fever were tested with an indirect immunofluorescence assay (IFA) and an enzyme-linked immunosorbent assay (ELISA) that used whole cells of B. recurrentis and with immunoblotting to whole-cell lysates of the spirochete and Escherichia coli producing recombinant GlpQ. The geometric mean titers of the acute- and convalescent-phase serum samples measured by IFA were 1:83 and 1:575, respectively. The immunoblot analysis identified a high level of reactivity and seroconversion to GlpQ, and the assay was more sensitive than the whole-cell IFA and ELISA using purified, recombinant histidine-tagged GlpQ. Serum antibodies to GlpQ and other antigens persisted for 27 years in one patient. We conclude that assessment of anti-GlpQ antibodies will allow serological confirmation of louse-borne relapsing fever and determination of disease prevalence. PMID:11015364

  3. Palmitic acid acutely inhibits acetylcholine- but not GLP-1-stimulated insulin secretion in mouse pancreatic islets

    PubMed Central

    Qin, Wei; Vinogradov, Sergei A.; Wilson, David F.; Matschinsky, Franz M.

    2010-01-01

    Fatty acids, acetylcholine, and GLP-1 enhance insulin secretion in a glucose-dependent manner. However, the interplay between glucose, fatty acids, and the neuroendocrine regulators of insulin secretion is not well understood. Therefore, we studied the acute effects of PA (alone or in combination with glucose, acetylcholine, or GLP-1) on isolated cultured mouse islets. Two different sets of experiments were designed. In one, a fixed concentration of 0.5 mM of PA bound to 0.15 mM BSA was used; in the other, a PA ramp from 0 to 0.5 mM was applied at a fixed albumin concentration of 0.15 mM so that the molar PA/BSA ratio changed within the physiological range. At a fixed concentration of 0.5 mM, PA markedly inhibited acetylcholine-stimulated insulin release, the rise of intracellular Ca2+, and enhancement of cAMP production but did not influence the effects of GLP-1 on these parameters of islet cell function. 2-ADB, an IP3 receptor inhibitor, reduced the effect of acetylcholine on insulin secretion and reversed the effect of PA on acetylcholine-stimulated insulin release. Islet perfusion for 35–40 min with 0.5 mM PA significantly reduced the calcium storage capacity of ER measured by the thapsigargin-induced Ca2+ release. Oxygen consumption due to low but not high glucose was reduced by PA. When a PA ramp from 0 to 0.5 mM was applied in the presence of 8 mM glucose, PA at concentrations as low as 50 μM significantly augmented glucose-stimulated insulin release and markedly reduced acetylcholine's effects on hormone secretion. We thus demonstrate that PA acutely reduces the total oxygen consumption response to glucose, glucose-dependent acetylcholine stimulation of insulin release, Ca2+, and cAMP metabolism, whereas GLP-1's actions on these parameters remain unaffected or potentiated. We speculate that acute emptying of the ER calcium by PA results in decreased glucose stimulation of respiration and acetylcholine potentiation of insulin secretion. PMID:20606076

  4. GlpR is a direct transcriptional repressor of fructose metabolic genes in Haloferax volcanii.

    PubMed

    Martin, Jonathan H; Rawls, Katie Sherwood; Chan, Jou Chin; Hwang, Sungmin; Martinez-Pastor, Mar; McMillan, Lana J; Prunetti, Laurence; Schmid, Amy K; Maupin-Furlow, Julie A

    2018-06-18

    DeoR-type helix-turn-helix (HTH) domain proteins are transcriptional regulators of sugar and nucleoside metabolism in diverse bacteria and occur in select archaea. In the model archaeon Haloferax volcanii , previous work implicated GlpR, a DeoR-type transcriptional regulator, in transcriptional repression of glpR and the gene encoding the fructose-specific phosphofructokinase ( pfkB ) during growth on glycerol. However, the global regulon governed by GlpR remained unclear. Here we compared transcriptomes of wild type and Δ glpR mutant strains grown on glycerol and glucose to detect significant transcript level differences for nearly 50 new genes regulated by GlpR. By coupling computational prediction of GlpR binding sequences with in vivo and in vitro DNA binding experiments, we determined that GlpR directly controls genes encoding enzymes in fructose degradation, including fructose bisphosphate aldolase, a central control point in glycolysis. GlpR also directly controls other transcription factors. In contrast, other metabolic pathways appear to be under indirect influence of GlpR. In vitro experiments demonstrated that GlpR purifies as a tetramer that binds the effector molecule fructose-1-phosphate (F1P). These results suggest that Hfx. volcanii GlpR functions as a direct negative regulator of fructose degradation during growth on carbon sources other than fructose, such as glucose and glycerol, and that GlpR bears striking functional similarity to bacterial DeoR-type regulators. IMPORTANCE Many archaea are extremophiles, able to thrive in habitats of extreme salinity, pH and temperature. These biological properties are ideal for applications in biotechnology. However, limited knowledge of archaeal metabolism is a bottleneck that prevents broad use of archaea as microbial factories for industrial products. Here we characterize how sugar uptake and use is regulated in a species that lives in high salinity. We demonstrate that a key sugar regulatory protein in

  5. The DPP-IV inhibitor linagliptin and GLP-1 induce synergistic effects on body weight loss and appetite suppression in the diet-induced obese rat.

    PubMed

    Hansen, Henrik H; Hansen, Gitte; Paulsen, Sarah; Vrang, Niels; Mark, Michael; Jelsing, Jacob; Klein, Thomas

    2014-10-15

    Linagliptin is a dipeptidyl peptidase (DPP)-IV inhibitor approved for the treatment of type 2 diabetes. DPP-IV inhibitors are considered weight neutral, suggesting that elevation of endogenous incretin levels is not sufficient to promote weight loss per se. Here we evaluated the effect of linagliptin in combination with subcutaneous treatment of GLP-1(7-36) on body weight regulation in diet-induced obese (DIO) rats. Linagliptin administered perorally (1.5mg/kg, b.i.d.), but not subcutaneously (0.5mg/kg, b.i.d.), evoked a very modest body weight loss (2.2%) after 28 days of treatment. GLP-1 (0.5mg/kg, s.c.) treatment alone induced a body weight loss of 4.1%. In contrast, combined linagliptin (1.5mg/kg, p.o., or 0.5mg/kg, s.c.) and GLP-1 (0.5mg/kg) treatment evoked a marked anorectic response with both routes of linagliptin administration being equally effective on final body weight loss (7.5-8.0%). In comparison, liraglutide monotherapy (0.2mg/kg, s.c., b.i.d.) reduced body weight by 10.1%. Interestingly, the weight lowering effect of combined linagliptin and GLP-1 treatment was associated with a marked increase in chow preference, being more pronounced as compared to liraglutide treatment. In addition, linagliptin and GLP-1 co-treatment, but not liraglutide, specifically increased prepro-dynorphin mRNA levels in the caudate-putamen, an effect not obtained with administration of the compounds individually. In conclusion, co-treatment with linagliptin and GLP-1 synergistically reduces body weight in obese rats. The anti-obesity effect was caused by appetite suppression with a concomitant change in diet preference, which may potentially be associated with increased dynorphin activity in forebrain regions involved in reward anticipation and habit learning. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Exendin-4, a glucagon-like peptide 1 receptor agonist, protects against amyloid-β peptide-induced impairment of spatial learning and memory in rats.

    PubMed

    Jia, Xiao-Tao; Ye-Tian; Yuan-Li; Zhang, Ge-Juan; Liu, Zhi-Qin; Di, Zheng-Li; Ying, Xiao-Ping; Fang, Yan; Song, Er-Fei; Qi, Jin-Shun; Pan, Yan-Fang

    2016-05-15

    Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) share specific molecular mechanisms, and agents with proven efficacy in one may be useful against the other. The glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 has similar properties to GLP-1 and is currently in clinical use for T2DM treatment. Thus, this study was designed to characterize the effects of exendin-4 on the impairment of learning and memory induced by amyloid protein (Aβ) and its probable molecular underlying mechanisms. The results showed that (1) intracerebroventricular (i.c.v.) injection of Aβ1-42 resulted in a significant decline of spatial learning and memory of rats in water maze tests; (2) pretreatment with exendin-4 effectively and dose-dependently protected against the Aβ1-42-induced impairment of spatial learning and memory; (3) exendin-4 treatment significantly decreased the expression of Bax and cleaved caspase-3 and increased the expression of Bcl2 in Aβ1-42-induced Alzheimer's rats. The vision and swimming speed of the rats among all groups in the visible platform tests did not show any difference. These findings indicate that systemic pretreatment with exendin-4 can effectively prevent the behavioral impairment induced by neurotoxic Aβ1-42, and the underlying protective mechanism of exendin-4 may be involved in the Bcl2, Bax and caspase-3 pathways. Thus, the application of exendin-4 or the activation of its signaling pathways may be a promising strategy to ameliorate the degenerative processes observed in AD. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Role of lateral septum glucagon-like peptide 1 receptors in food intake

    PubMed Central

    Jackson, Christine M.; Greene, Hayden E.; Lilly, Nicole; Maske, Calyn B.; Vallejo, Samantha

    2016-01-01

    Hindbrain glucagon-like peptide 1 (GLP-1) neurons project to numerous forebrain areas, including the lateral septum (LS). Using a fluorescently labeled GLP-1 receptor (GLP-1R) agonist, Exendin 4 (Ex4), we demonstrated GLP-1 receptor binding throughout the rat LS. We examined the feeding effects of Ex4 and the GLP-1R antagonist Exendin (9–39) (Ex9) at doses subthreshold for effect when delivered to the lateral ventricle. Intra-LS Ex4 suppressed overnight chow and high-fat diet (HFD) intake, and Ex9 increased chow and HFD intake relative to vehicle. During 2-h tests, intra-LS Ex9 significantly increased 0.25 M sucrose and 4% corn oil. Ex4 can cause nausea, but intra-LS administration of Ex4 did not induce pica. Furthermore, intra-LS Ex4 had no effect on anxiety-like behavior in the elevated plus maze. We investigated the role of LS GLP-1R in motivation for food by examining operant responding for sucrose on a progressive ratio (PR) schedule, with and without a nutrient preload to maximize GLP-1 neuron activation. The preload strongly suppressed PR responding, but blockade of GLP-1R in the intermediate subdivision of the LS did not affect motivation for sucrose under either load condition. The ability of the nutrient load to suppress subsequent chow intake was significantly attenuated by intermediate LS Ex9 treatment. By contrast, blockade of GLP-1R in the dorsal subdivision of the LS increased both PR responding and overnight chow intake. Together, these studies suggest that endogenous activity of GLP-1R in the LS influence feeding, and dLS GLP-1Rs, in particular, play a role in motivation. PMID:27194565

  8. Role of lateral septum glucagon-like peptide 1 receptors in food intake.

    PubMed

    Terrill, Sarah J; Jackson, Christine M; Greene, Hayden E; Lilly, Nicole; Maske, Calyn B; Vallejo, Samantha; Williams, Diana L

    2016-07-01

    Hindbrain glucagon-like peptide 1 (GLP-1) neurons project to numerous forebrain areas, including the lateral septum (LS). Using a fluorescently labeled GLP-1 receptor (GLP-1R) agonist, Exendin 4 (Ex4), we demonstrated GLP-1 receptor binding throughout the rat LS. We examined the feeding effects of Ex4 and the GLP-1R antagonist Exendin (9-39) (Ex9) at doses subthreshold for effect when delivered to the lateral ventricle. Intra-LS Ex4 suppressed overnight chow and high-fat diet (HFD) intake, and Ex9 increased chow and HFD intake relative to vehicle. During 2-h tests, intra-LS Ex9 significantly increased 0.25 M sucrose and 4% corn oil. Ex4 can cause nausea, but intra-LS administration of Ex4 did not induce pica. Furthermore, intra-LS Ex4 had no effect on anxiety-like behavior in the elevated plus maze. We investigated the role of LS GLP-1R in motivation for food by examining operant responding for sucrose on a progressive ratio (PR) schedule, with and without a nutrient preload to maximize GLP-1 neuron activation. The preload strongly suppressed PR responding, but blockade of GLP-1R in the intermediate subdivision of the LS did not affect motivation for sucrose under either load condition. The ability of the nutrient load to suppress subsequent chow intake was significantly attenuated by intermediate LS Ex9 treatment. By contrast, blockade of GLP-1R in the dorsal subdivision of the LS increased both PR responding and overnight chow intake. Together, these studies suggest that endogenous activity of GLP-1R in the LS influence feeding, and dLS GLP-1Rs, in particular, play a role in motivation. Copyright © 2016 the American Physiological Society.

  9. Glucagon-Like Peptide-1 and Its Class B G Protein–Coupled Receptors: A Long March to Therapeutic Successes

    PubMed Central

    de Graaf, Chris; Donnelly, Dan; Wootten, Denise; Lau, Jesper; Sexton, Patrick M.; Miller, Laurence J.; Ahn, Jung-Mo; Liao, Jiayu; Fletcher, Madeleine M.; Brown, Alastair J. H.; Zhou, Caihong; Deng, Jiejie; Wang, Ming-Wei

    2016-01-01

    The glucagon-like peptide (GLP)-1 receptor (GLP-1R) is a class B G protein–coupled receptor (GPCR) that mediates the action of GLP-1, a peptide hormone secreted from three major tissues in humans, enteroendocrine L cells in the distal intestine, α cells in the pancreas, and the central nervous system, which exerts important actions useful in the management of type 2 diabetes mellitus and obesity, including glucose homeostasis and regulation of gastric motility and food intake. Peptidic analogs of GLP-1 have been successfully developed with enhanced bioavailability and pharmacological activity. Physiologic and biochemical studies with truncated, chimeric, and mutated peptides and GLP-1R variants, together with ligand-bound crystal structures of the extracellular domain and the first three-dimensional structures of the 7-helical transmembrane domain of class B GPCRs, have provided the basis for a two-domain–binding mechanism of GLP-1 with its cognate receptor. Although efforts in discovering therapeutically viable nonpeptidic GLP-1R agonists have been hampered, small-molecule modulators offer complementary chemical tools to peptide analogs to investigate ligand-directed biased cellular signaling of GLP-1R. The integrated pharmacological and structural information of different GLP-1 analogs and homologous receptors give new insights into the molecular determinants of GLP-1R ligand selectivity and functional activity, thereby providing novel opportunities in the design and development of more efficacious agents to treat metabolic disorders. PMID:27630114

  10. The Effects of Aerobic Exercises and 25(OH) D Supplementation on GLP1 and DPP4 Level in Type II Diabetic Patients.

    PubMed

    Rahimi, Naser; Samavati Sharif, Mohammad Ali; Goharian, Amir Reza; Pour, Ali Heidarian

    2017-01-01

    The purpose of this study was to investigate the effects of an 8-week aerobic exercise and supplementation of 25(OH)D3 on GLP1 and DDP4 levels in men with type II diabetes. In this semiexperimental research, among 40-60-year-old men with type II diabetes who were referred to the diabetic center of Isabn-E Maryam hospital in Isfahan; of whom, 48 patients were voluntarily accepted and then were randomly divided into 4 groups: aerobic exercise group, aerobic exercise with 25(OH) D supplement group, 25(OH) D supplement group, and the control group. An aerobic exercise program was conducted for 8 weeks (3 sessions/week, each session 60 to75 min with 60-80% HRmax). The supplement user group received 50,000 units of oral Vitamin D once weekly for 8 weeks. The GLP1, DPP4, and 25(OH) D levels were measured before and after the intervention. At last, the data were statistically analyzed using the ANCOVA and post hoc test of least significant difference. The results of ANCOVA showed a significant difference between the GLP1 and DPP4 levels in aerobic exercise with control group while these changes were not statistically significant between the 25(OH) D supplement group with control group ( P < 0.05). Aerobic exercises have resulted an increase in GLP1 level and a decrease in DPP4 level. However, consumption of Vitamin D supplement alone did not cause any changes in GLP1and DPP4 levels but led to an increase in 25-hydroxy Vitamin D level.

  11. Glucagon-like peptide-1 regulates brown adipose tissue thermogenesis via the gut-brain axis in rats.

    PubMed

    Krieger, Jean-Philippe; Santos da Conceição, Ellen Paula; Sanchez-Watts, Graciela; Arnold, Myrtha; Pettersen, Klaus G; Mohammed, Mazher; Modica, Salvatore; Lossel, Pius; Morrison, Shaun F; Madden, Christopher J; Watts, Alan G; Langhans, Wolfgang; Lee, Shin J

    2018-05-30

    Endogenous intestinal glucagon-like peptide-1 (GLP-1) controls satiation and glucose metabolism via vagal afferent neurons (VAN). Recently, VAN have received increasing attention for their role in brown adipose tissue (BAT) thermogenesis. It is however unclear whether VAN GLP-1 receptor (GLP-1R) signaling affects BAT thermogenesis and energy expenditure (EE), and whether this VAN mechanism contributes to energy balance. First, we tested the effect of the GLP-1R agonist Exendin-4 (Ex4, 0.3 μg/kg IP) on EE and BAT thermogenesis, and whether these effects require VAN GLP-1R signaling, using a rat model with a selective Glp1r knockdown (kd) in VAN. Second, we examined the role of VAN GLP-1R in energy balance during chronic high-fat diet (HFD) feeding in VAN Glp1r kd rats. Lastly, we used viral transsynaptic tracers to identify the possible neuronal substrates of such a gut-BAT interaction. VAN Glp1r kd attenuated the acute suppressive effects of Ex4 on EE and BAT thermogenesis. Consistent with this finding, the VAN Glp1r kd increased EE and BAT activity, diminished body weight gain, and improved insulin sensitivity compared to HFD-fed controls. Anterograde transsynaptic viral tracing of VAN infected major hypothalamic and hindbrain areas involved in BAT sympathetic regulation. Moreover, retrograde tracing from BAT combined with laser capture microdissection revealed that a population of VAN expressing Glp1r is synaptically connected to the BAT. Our findings reveal a novel role of VAN GLP-1R signaling in the regulation of EE and BAT thermogenesis, and imply that through this gut-brain-BAT connection intestinal GLP-1 plays a role in HFD-induced metabolic syndrome.

  12. Dulaglutide, a long-acting GLP-1 analog fused with an Fc antibody fragment for the potential treatment of type 2 diabetes.

    PubMed

    Jimenez-Solem, Espen; Rasmussen, Mette H; Christensen, Mikkel; Knop, Filip K

    2010-12-01

    Dulaglutide (LY-2189265) is a novel, long-acting glucagon-like peptide 1 (GLP-1) analog being developed by Eli Lilly for the treatment of type 2 diabetes mellitus (T2DM). Dulaglutide consists of GLP-1(7-37) covalently linked to an Fc fragment of human IgG4, thereby protecting the GLP-1 moiety from inactivation by dipeptidyl peptidase 4. In vitro and in vivo studies on T2DM models demonstrated glucose-dependent insulin secretion stimulation. Pharmacokinetic studies demonstrated a t1/2 in humans of up to 90 h, making dulaglutide an ideal candidate for once-weekly dosing. Clinical trials suggest that dulaglutide reduces plasma glucose, and has an insulinotropic effect increasing insulin and C-peptide levels. Two phase II clinical trials demonstrated a dose-dependent reduction in glycated hemoglobin (HbA1c) of up to 1.52% compared with placebo. Side effects associated with dulaglutide administration were mainly gastrointestinal. To date, there have been no reports on the formation of antibodies against dulaglutide, but, clearly, long-term data will be needed to asses this and other possible side effects. The results of several phase III clinical trials are awaited for clarification of the expected effects on HbA1c and body weight. If dulaglutide possesses similar efficacy to other GLP-1 analogs, the once-weekly treatment will most likely be welcomed by patients with T2DM.

  13. What next after basal insulin? Treatment intensification with lixisenatide in Asian patients with type 2 diabetes mellitus.

    PubMed

    Chan, Wing B; Luk, Andrea; Chow, Wing S; Yeung, Vincent T F

    2017-06-01

    There is increasing evidence that the pathophysiology of type 2 diabetes mellitus (T2DM) in Asian patients differs from that in Western patients, with early phase insulin deficiencies, increased postprandial glucose excursions, and increased sensitivity to insulin. Asian patients may also experience higher rates of gastrointestinal adverse events associated with glucagon-like peptide-1 receptor agonists (GLP-1RAs), such as nausea and vomiting, compared with their Western counterparts. These factors should be taken into consideration when selecting therapy for basal insulin treatment intensification in Asian patients. However, the majority of studies to establish various agents for treatment intensification in T2DM have been conducted in predominantly Western populations, and the levels of evidence available in Chinese or Asian patients are limited. This review discusses the different mechanisms of action of short-acting, prandial, and long-acting GLP-1RAs in addressing hyperglycemia, and describes the rationale and available clinical data for basal insulin in combination with the short-acting prandial GLP-1RA lixisenatide, with a focus on treatment of Asian patients with T2DM. © 2016 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

  14. GLP-1 receptors exist in the parietal cortex, hypothalamus and medulla of human brains and the GLP-1 analogue liraglutide alters brain activity related to highly desirable food cues in individuals with diabetes: a crossover, randomised, placebo-controlled trial

    PubMed Central

    Farr, Olivia M.; Sofopoulos, Michail; Tsoukas, Michael A.; Dincer, Fadime; Thakkar, Bindiya; Sahin-Efe, Ayse; Filippaios, Andreas; Bowers, Jennifer; Srnka, Alexandra; Gavrieli, Anna; Ko, Byung-Joon; Liakou, Chrysoula; Kanyuch, Nickole; Tseleni-Balafouta, Sofia; Mantzoros, Christos S.

    2016-01-01

    Aims/hypothesis Liraglutide is a glucagon-like peptide-1 (GLP-1) analogue that has been demonstrated to successfully treat diabetes and promote weight loss. The mechanisms by which liraglutide confers weight loss remain to be fully clarified. Thus, we investigated whether GLP-1 receptors are expressed in human brains and whether liraglutide administration affects neural responses to food cues in diabetic individuals (primary outcome). Methods In 22 consecutively studied human brains, expression of GLP-1 receptors in the hypothalamus, medulla oblongata and parietal cortex was examined using immunohistochemistry. In a randomised (assigned by the pharmacy using a randomisation enrollment table), placebo-controlled, double-blind, crossover trial, 21 individuals with type 2 diabetes (18 included in analysis due to lack or poor quality of data) were treated with placebo and liraglutide for a total of 17 days each (0.6 mg for 7 days, 1.2 mg for 7 days and 1.8 mg for 3 days). Participants were eligible if they had type 2 diabetes and were currently being treated with lifestyle changes or metformin. Participants, caregivers, people doing measurements and/or examinations, and people assessing the outcomes were blinded to the medication assignment. We studied metabolic changes as well as neurocognitive and neuroimaging (fMRI) of responses to food cues at the clinical research centre of Beth Israel Deaconess Medical Center. Results Immunohistochemical analysis revealed the presence of GLP-1 receptors on neurons in the human hypothalamus, medulla and parietal cortex. Liraglutide decreased activation of the parietal cortex in response to highly desirable (vs less desirable) food images (p < 0.001; effect size: placebo 0.53 ± 0.24, liraglutide −0.47 ± 0.18). No significant adverse effects were noted. In a secondary analysis, we observed decreased activation in the insula and putamen, areas involved in the reward system. Furthermore, we showed that increased ratings of hunger

  15. GLP-2 receptor in POMC neurons suppresses feeding behavior and gastric motility

    USDA-ARS?s Scientific Manuscript database

    Glucagon-like peptides (GLP-1/2) are cosecreted from endocrine L cells in the gut and preproglucagonergic neurons in the brain. Peripheral GLP-2 action is essential for maintaining intestinal homeostasis, improving absorption efficiency and blood flow, promoting immune defense, and producing efficac...

  16. Lysophosphatidylinositol-induced activation of the cation channel TRPV2 triggers glucagon-like peptide-1 secretion in enteroendocrine L cells.

    PubMed

    Harada, Kazuki; Kitaguchi, Tetsuya; Kamiya, Taichi; Aung, Kyaw Htet; Nakamura, Kazuaki; Ohta, Kunihiro; Tsuboi, Takashi

    2017-06-30

    The lysophosphatidylinositol (LPI) has crucial roles in multiple physiological processes, including insulin exocytosis from pancreatic islets. However, the role of LPI in secretion of glucagon-like peptide-1 (GLP-1), a hormone that enhances glucose-induced insulin secretion, is unclear. Here, we used the murine enteroendocrine L cell line GLUTag and primary murine small intestinal cells to elucidate the mechanism of LPI-induced GLP-1 secretion. Exogenous LPI addition increased intracellular Ca 2+ concentrations ([Ca 2+ ] i ) in GLUTag cells and induced GLP-1 secretion from both GLUTag and acutely prepared primary intestinal cells. The [Ca 2+ ] i increase was suppressed by an antagonist for G protein-coupled receptor 55 (GPR55) and by silencing of GPR55 expression, indicating involvement of G q and G 12/13 signaling pathways in the LPI-induced increased [Ca 2+ ] i levels and GLP-1 secretion. However, GPR55 agonists did not mimic many of the effects of LPI. We also found that phospholipase C inhibitor and Rho-associated kinase inhibitor suppressed the [Ca 2+ ] i increase and that LPI increased the number of focal adhesions, indicating actin reorganization. Of note, blockage or silencing of transient receptor potential cation channel subfamily V member 2 (TRPV2) channels suppressed both the LPI-induced [Ca 2+ ] i increase and GLP-1 secretion. Furthermore, LPI accelerated TRPV2 translocation to the plasma membrane, which was significantly suppressed by a GPR55 antagonist. These findings suggest that TRPV2 activation via actin reorganization induced by G q and G 12/13 signaling is involved in LPI-stimulated GLP-1 secretion in enteroendocrine L cells. Because GPR55 agonists largely failed to mimic the effects of LPI, its actions on L cells are at least partially independent of GPR55 activation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. Glucagon Like Peptide-1 (GLP-1) Modulates OVA-Induced Airway Inflammation and Mucus Secretion Involving a Protein Kinase A (PKA)-Dependent Nuclear Factor-κB (NF-κB) Signaling Pathway in Mice.

    PubMed

    Zhu, Tao; Wu, Xiao-Ling; Zhang, Wei; Xiao, Min

    2015-08-26

    Asthma is a common chronic pulmonary inflammatory disease, featured with mucus hyper-secretion in the airway. Recent studies found that glucagon like peptide-1 (GLP-1) analogs, including liraglutide and exenatide, possessed a potent anti-inflammatory property through a protein kinase A (PKA)-dependent signaling pathway. Therefore, the aim of current study was to investigate the value of GLP-1 analog therapy liraglutide in airway inflammation and mucus secretion in a murine model of ovalbumin (OVA)-induced asthma, and its underlying molecular mechanism. In our study, BALB/c mice were sensitized and challenged by OVA to induce chronic asthma. Pathological alterations, the number of cells and the content of inflammatory mediators in bronchoalveolar lavage fluid (BALF), and mucus secretion were observed and measured. In addition, the mRNA and protein expression of E-selectin and MUC5AC were analyzed by qPCR and Western blotting. Then, the phosphorylation of PKA and nuclear factor-κB (NF-κB) p65 were also measured by Western blotting. Further, NF-κB p65 DNA binding activity was detected by ELISA. OVA-induced airway inflammation, airway mucus hyper-secretion, the up-regulation of E-selectin and MUC5AC were remarkably inhibited by GLP-1 in mice (all p < 0.01). Then, we also found that OVA-reduced phosphorylation of PKA, and OVA-enhanced NF-κB p65 activation and NF-κB p65 DNA binding activity were markedly improved by GLP-1 (all p < 0.01). Furthermore, our data also figured out that these effects of GLP-1 were largely abrogated by the PKA inhibitor H-89 (all p < 0.01). Taken together, our results suggest that OVA-induced asthma were potently ameliorated by GLP-1 possibly through a PKA-dependent inactivation of NF-κB in mice, indicating that GLP-1 analogs may be considered an effective and safe drug for the potential treatment of asthma in the future.

  18. Co-culture of clonal beta cells with GLP-1 and glucagon-secreting cell line impacts on beta cell insulin secretion, proliferation and susceptibility to cytotoxins.

    PubMed

    Green, Alastair D; Vasu, Srividya; Moffett, R Charlotte; Flatt, Peter R

    2016-06-01

    We investigated the direct effects on insulin releasing MIN6 cells of chronic exposure to GLP-1, glucagon or a combination of both peptides secreted from GLUTag L-cell and αTC1.9 alpha-cell lines in co-culture. MIN6, GLUTag and αTC1.9 cell lines exhibited high cellular hormone content and release of insulin, GLP-1 and glucagon, respectively. Co-culture of MIN6 cells with GLUTag cells significantly increased cellular insulin content, beta-cell proliferation, insulin secretory responses to a range of established secretogogues and afforded protection against exposure cytotoxic concentrations of glucose, lipid, streptozotocin or cytokines. Benefits of co-culture of MIN6 cells with αTC1.9 alphacells were limited to enhanced beta-cell proliferation with marginal positive actions on both insulin secretion and cellular protection. In contrast, co-culture of MIN6 with GLUTag cells plus αTC1.9 cells, markedly enhanced both insulin secretory responses and protection against beta-cell toxins compared with co-culture with GLUTag cells alone. These data indicate important long-term effects of conjoint GLP-1 and glucagon exposure on beta-cell function. This illustrates the possible functional significance of alpha-cell GLP-1 production as well as direct beneficial effects of dual agonism at beta-cell GLP-1 and glucagon receptors. Copyright © 2016 Elsevier B.V. and Société française de biochimie et biologie Moléculaire (SFBBM). All rights reserved.

  19. Endogenous GLP-1 mediates postprandial reductions in activation in central reward and satiety areas in patients with type 2 diabetes.

    PubMed

    ten Kulve, Jennifer S; Veltman, Dick J; van Bloemendaal, Liselotte; Barkhof, Frederik; Deacon, Carolyn F; Holst, Jens J; Konrad, Robert J; Sloan, John H; Drent, Madeleine L; Diamant, Michaela; IJzerman, Richard G

    2015-12-01

    The central nervous system (CNS) is a major player in the regulation of food intake. The gut hormone glucagon-like peptide-1 (GLP-1) has been proposed to have an important role in this regulation by relaying information about nutritional status to the CNS. We hypothesised that endogenous GLP-1 has effects on CNS reward and satiety circuits. This was a randomised, crossover, placebo-controlled intervention study, performed in a university medical centre in the Netherlands. We included patients with type 2 diabetes and healthy lean control subjects. Individuals were eligible if they were 40-65 years. Inclusion criteria for the healthy lean individuals included a BMI <25 kg/m(2) and normoglycaemia. Inclusion criteria for the patients with type 2 diabetes included BMI >26 kg/m(2), HbA1c levels between 42 and 69 mmol/mol (6.0-8.5%) and treatment for diabetes with only oral glucose-lowering agents. We assessed CNS activation, defined as blood oxygen level dependent (BOLD) signal, in response to food pictures in obese patients with type 2 diabetes (n = 20) and healthy lean individuals (n = 20) using functional magnetic resonance imaging (fMRI). fMRI was performed in the fasted state and after meal intake on two occasions, once during infusion of the GLP-1 receptor antagonist exendin 9-39, which was administered to block actions of endogenous GLP-1, and on the other occasion during saline (placebo) infusion. Participants were blinded for the type of infusion. The order of infusion was determined by block randomisation. The primary outcome was the difference in BOLD signal, i.e. in CNS activation, in predefined regions in the CNS in response to viewing food pictures. All patients were included in the analyses. Patients with type 2 diabetes showed increased CNS activation in CNS areas involved in the regulation of feeding (insula, amygdala and orbitofrontal cortex) in response to food pictures compared with lean individuals (p ≤ 0.04). Meal intake reduced activation in the

  20. Quantification of the Contribution of GLP-1 to Mediating Insulinotropic Effects of DPP-4 Inhibition With Vildagliptin in Healthy Subjects and Patients With Type 2 Diabetes Using Exendin [9-39] as a GLP-1 Receptor Antagonist.

    PubMed

    Nauck, Michael A; Kind, Joachim; Köthe, Lars D; Holst, Jens J; Deacon, Carolyn F; Broschag, Matthias; He, Yan Ling; Kjems, Lise; Foley, James

    2016-08-01

    We quantified the contribution of GLP-1 as a mediator of the therapeutic effects of dipeptidyl peptidase 4 (DPP-4) inhibition (vildagliptin) by using the GLP-1 receptor antagonist exendin [9-39] in patients with type 2 diabetes and in healthy subjects. Thirty-two patients with type 2 diabetes and 29 age- and weight-matched healthy control subjects were treated in randomized order with 100 mg once daily vildagliptin or placebo for 10 days. Meal tests were performed (days 9 and 10) without and with a high-dose intravenous infusion of exendin [9-39]. The main end point was the ratio of the areas under the curve (AUCs) of integrated insulin secretion rates (total AUCISR) and glucose (total AUCglucose) over 4 h after the meal. Vildagliptin treatment more than doubled responses of intact GLP-1 and glucose-dependent insulinotropic polypeptide and lowered glucose responses without changing AUCISR/AUCglucose in healthy subjects. Vildagliptin significantly increased this ratio by 10.5% in patients with type 2 diabetes, and exendin [9-39] reduced it (both P < 0.0001). The percentage reduction in the AUCISR/AUCglucose ratio achieved with exendin [9-39] was significantly smaller after vildagliptin treatment than after placebo treatment (P = 0.026) and was equivalent to 47 ± 5% of the increments due to vildagliptin. Thus, other mediators appear to contribute significantly to the therapeutic effects of DPP-4 inhibition. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  1. GLP-1 receptors exist in the parietal cortex, hypothalamus and medulla of human brains and the GLP-1 analogue liraglutide alters brain activity related to highly desirable food cues in individuals with diabetes: a crossover, randomised, placebo-controlled trial.

    PubMed

    Farr, Olivia M; Sofopoulos, Michail; Tsoukas, Michael A; Dincer, Fadime; Thakkar, Bindiya; Sahin-Efe, Ayse; Filippaios, Andreas; Bowers, Jennifer; Srnka, Alexandra; Gavrieli, Anna; Ko, Byung-Joon; Liakou, Chrysoula; Kanyuch, Nickole; Tseleni-Balafouta, Sofia; Mantzoros, Christos S

    2016-05-01

    Liraglutide is a glucagon-like peptide-1 (GLP-1) analogue that has been demonstrated to successfully treat diabetes and promote weight loss. The mechanisms by which liraglutide confers weight loss remain to be fully clarified. Thus, we investigated whether GLP-1 receptors are expressed in human brains and whether liraglutide administration affects neural responses to food cues in diabetic individuals (primary outcome). In 22 consecutively studied human brains, expression of GLP-1 receptors in the hypothalamus, medulla oblongata and parietal cortex was examined using immunohistochemistry. In a randomised (assigned by the pharmacy using a randomisation enrolment table), placebo-controlled, double-blind, crossover trial, 21 individuals with type 2 diabetes (18 included in analysis due to lack or poor quality of data) were treated with placebo and liraglutide for a total of 17 days each (0.6 mg for 7 days, 1.2 mg for 7 days, and 1.8 mg for 3 days). Participants were eligible if they had type 2 diabetes and were currently being treated with lifestyle changes or metformin. Participants, caregivers, people doing measurements and/or examinations, and people assessing the outcomes were blinded to the medication assignment. We studied metabolic changes as well as neurocognitive and neuroimaging (functional MRI) of responses to food cues at the clinical research centre of Beth Israel Deaconess Medical Center. Immunohistochemical analysis revealed the presence of GLP-1 receptors on neurons in the human hypothalamus, medulla and parietal cortex. Liraglutide decreased activation of the parietal cortex in response to highly desirable (vs less desirable) food images (p < 0.001; effect size: placebo 0.53 ± 0.24, liraglutide -0.47 ± 0.18). No significant adverse effects were noted. In a secondary analysis, we observed decreased activation in the insula and putamen, areas involved in the reward system. Furthermore, we showed that increased ratings of hunger and

  2. Central GLP-2 enhances hepatic insulin sensitivity via activating PI3K signaling in POMC neurons

    USDA-ARS?s Scientific Manuscript database

    Glucagon-like peptides (GLP-1/GLP-2) are coproduced and highlighted as key modulators to improve glucose homeostasis and insulin sensitivity after bariatric surgery. However, it is unknown if CNS GLP-2 plays any physiological role in the control of glucose homeostasis and insulin sensitivity. We sho...

  3. Methylation of DNA Ligase 1 by G9a/GLP Recruits UHRF1 to Replicating DNA and Regulates DNA Methylation.

    PubMed

    Ferry, Laure; Fournier, Alexandra; Tsusaka, Takeshi; Adelmant, Guillaume; Shimazu, Tadahiro; Matano, Shohei; Kirsh, Olivier; Amouroux, Rachel; Dohmae, Naoshi; Suzuki, Takehiro; Filion, Guillaume J; Deng, Wen; de Dieuleveult, Maud; Fritsch, Lauriane; Kudithipudi, Srikanth; Jeltsch, Albert; Leonhardt, Heinrich; Hajkova, Petra; Marto, Jarrod A; Arita, Kyohei; Shinkai, Yoichi; Defossez, Pierre-Antoine

    2017-08-17

    DNA methylation is an essential epigenetic mark in mammals that has to be re-established after each round of DNA replication. The protein UHRF1 is essential for this process; it has been proposed that the protein targets newly replicated DNA by cooperatively binding hemi-methylated DNA and H3K9me2/3, but this model leaves a number of questions unanswered. Here, we present evidence for a direct recruitment of UHRF1 by the replication machinery via DNA ligase 1 (LIG1). A histone H3K9-like mimic within LIG1 is methylated by G9a and GLP and, compared with H3K9me2/3, more avidly binds UHRF1. Interaction with methylated LIG1 promotes the recruitment of UHRF1 to DNA replication sites and is required for DNA methylation maintenance. These results further elucidate the function of UHRF1, identify a non-histone target of G9a and GLP, and provide an example of a histone mimic that coordinates DNA replication and DNA methylation maintenance. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Experience with the high-intensity sweetener saccharin impairs glucose homeostasis and GLP-1 release in rats

    PubMed Central

    Swithers, Susan E.; Laboy, Alycia F.; Clark, Kiely; Cooper, Stephanie; Davidson, T.L.

    2012-01-01

    Previous work from our lab has demonstrated that experience with high-intensity sweeteners in rats leads to increased food intake, body weight gain and adiposity, along with diminished caloric compensation and decreased thermic effect of food. These changes may occur as a result of interfering with learned relations between the sweet taste of food and the caloric or nutritive consequences of consuming those foods. The present experiments determined whether experience with the high-intensity sweetener saccharin versus the caloric sweetener glucose affected blood glucose homeostasis. The results demonstrated that during oral glucose tolerance tests, blood glucose levels were more elevated in animals that had previously consumed the saccharin-sweetened supplements. In contrast, during glucose tolerance tests when a glucose solution was delivered directly into the stomach, no differences in blood glucose levels between the groups were observed. Differences in oral glucose tolerance responses were not accompanied by differences in insulin release; insulin release was similar in animals previously exposed to saccharin and those previously exposed to glucose. However, release of GLP-1 in response to an oral glucose tolerance test, but not to glucose tolerance tests delivered by gavage, was significantly lower in saccharin-exposed animals compared to glucose-exposed animals. Differences in both blood glucose and GLP-1 release in saccharin animals were rapid and transient, and suggest that one mechanism by which exposure to high-intensity sweeteners that interfere with a predictive relation between sweet tastes and calories may impair energy balance is by suppressing GLP-1 release, which could alter glucose homeostasis and reduce satiety. PMID:22561130

  5. Brain GLP-1/IGF-1 Signaling and Autophagy Mediate Exendin-4 Protection Against Apoptosis in Type 2 Diabetic Rats.

    PubMed

    Candeias, Emanuel; Sebastião, Inês; Cardoso, Susana; Carvalho, Cristina; Santos, Maria Sancha; Oliveira, Catarina Resende; Moreira, Paula I; Duarte, Ana I

    2018-05-01

    Type 2 diabetes (T2D) is a modern socioeconomic burden, mostly due to its long-term complications affecting nearly all tissues. One of them is the brain, whose dysfunctional intracellular quality control mechanisms (namely autophagy) may upregulate apoptosis, leading to cognitive dysfunction and Alzheimer disease (AD). Since impaired brain insulin signaling may constitute the crosslink between T2D and AD, its restoration may be potentially therapeutic herein. Accordingly, the insulinotropic anti-T2D drugs from glucagon-like peptide-1 (GLP-1) mimetics, namely, exendin-4 (Ex-4), could be a promising therapy. In line with this, we hypothesized that peripherally administered Ex-4 rescues brain intracellular signaling pathways, promoting autophagy and ultimately protecting against chronic T2D-induced apoptosis. Thus, we aimed to explore the effects of chronic, continuous, subcutaneous (s.c.) exposure to Ex-4 in brain cortical GLP-1/insulin/insulin-like growth factor-1 (IGF-1) signaling, and in autophagic and cell death mechanisms in middle-aged (8 months old), male T2D Goto-Kakizaki (GK) rats. We used brain cortical homogenates obtained from middle-aged (8 months old) male Wistar (control) and T2D GK rats. Ex-4 was continuously administered for 28 days, via s.c. implanted micro-osmotic pumps (5 μg/kg/day; infusion rate 2.5 μL/h). Peripheral characterization of the animal models was given by the standard biochemical analyses of blood or plasma, the intraperitoneal glucose tolerance test, and the heart rate. GLP-1, insulin, and IGF-1, their downstream signaling and autophagic markers were evaluated by specific ELISA kits and Western blotting. Caspase-like activities and other apoptotic markers were given by colorimetric methods and Western blotting. Chronic Ex-4 treatment attenuated peripheral features of T2D in GK rats, including hyperglycemia and insulin resistance. Furthermore, s.c. Ex-4 enhanced their brain cortical GLP-1 and IGF-1 levels, and subsequent

  6. Post-stroke infection: a role for IL-1ra?

    PubMed

    Tanzi, Pat; Cain, Kevin; Kalil, Angela; Zierath, Dannielle; Savos, Anna; Gee, J Michael; Shibata, Dean; Hadwin, Jessica; Carter, Kelly; Becker, Kyra

    2011-04-01

    Infection is common following stroke and is independently associated with worse outcome. Clinical studies suggest that infections occur more frequently in those individuals with stroke-induced immunologic dysfunction. This study sought to explore the contribution of immunomodulatory cytokines and hormones to lymphocyte function and infection risk. Patients (N = 112) were enrolled as soon as possible after the onset of ischemic stroke. Blood was drawn to assess plasma cortisol, IL-10, IL-1ra, lymphocyte numbers, and lymphocyte function at 72 h after stroke onset; infections were censored through 21 days after stroke onset. Infection occurred in 25% of patients. Stroke severity was the most important predictor of infection risk. Increased plasma cortisol, IL-10, and IL-1ra, as well as decreased lymphocyte numbers, at 72 h after stroke onset were associated with risk of subsequent infection. After controlling for stroke severity, only IL-1ra was independently associated with infection risk, and the degree of risk was consistent throughout the post-stroke period. Infection, but not IL-1ra itself, was associated with worse outcome at 3 months. In this study cohort, increased plasma IL-1ra was independently associated with the risk of post-stroke infection. Further studies are needed to validate this finding, which could have important implications for stroke therapy.

  7. Geometry of GLP on silver surface by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bao, PeiDi; Bao, Lang; Huang, TianQuan; Liu, XinMing; Wu, GuoFeng

    2000-05-01

    Leptospirosis is one of the most harmful zoonosis, it is a serious public health issue in some area of Sichuan province. Surface-Enhance Raman Scattering (SERS) Spectroscopy is an effective approach for the study of biomolecular adsorption on metal surface and provides information about the adsorbed species. Two samples of Leptospiral Glycolipoprotein (GLP-1) and GLP-2 which have different toxic effects have been obtained and investigated.

  8. Does GLP enhance the quality of toxicological evidence for regulatory decisions?

    PubMed Central

    Borgert, Christopher J.; Becker, Richard A.; Carlton, Betsy D.; Hanson, Mark; Kwiatkowski, Patricia L.; Sue Marty, Mary; McCarty, Lynn S.; Quill, Terry F.; Solomon, Keith; Van Der Kraak, Glen; Witorsch, Raphael J.; Don Yi, Kun

    2016-01-01

    There is debate over whether the requirements of GLP are appropriate standards for evaluating the quality of toxicological data used to formulate regulations. A group promoting the importance of non-monotonic dose responses for endocrine disruptors contend that scoring systems giving primacy to GLP are biased against non-GLP studies from the literature and are merely record-keeping exercises to prevent fraudulent reporting of data from non-published guideline toxicology studies. They argue that guideline studies often employ insensitive species and outdated methods, and ignore the perspectives of subject-matter experts in endocrine disruption, who should be the sole arbiters of data quality. We believe regulatory agencies should use both non-GLP and GLP studies, that GLP requirements assure fundamental tenets of study integrity not typically addressed by journal peer-review, and that use of standardized test guidelines and GLP promotes consistency, reliability, comparability, and harmonization of various types of studies used by regulatory agencies worldwide. This debate suffers two impediments to progress: a conflation of different phases of study interpretation and levels of data validity, and a misleading characterization of many essential components of GLP and regulatory toxicology. Herein we provide clarifications critical for removing those impediments. PMID:27208076

  9. Exenatide improves both hepatic and adipose tissue insulin resistance: A dynamic positron emission tomography study.

    PubMed

    Gastaldelli, Amalia; Gaggini, Melania; Daniele, Giuseppe; Ciociaro, Demetrio; Cersosimo, Eugenio; Tripathy, Devjit; Triplitt, Curtis; Fox, Peter; Musi, Nicolas; DeFronzo, Ralph; Iozzo, Patricia

    2016-12-01

    Glucagon-like peptide 1 (GLP-1) receptor agonists (GLP-1-RAs) act on multiple tissues, in addition to the pancreas. Recent studies suggest that GLP-1-RAs act on liver and adipose tissue to reduce insulin resistance (IR). Thus, we evaluated the acute effects of exenatide (EX) on hepatic (Hep-IR) and adipose (Adipo-IR) insulin resistance and glucose uptake. Fifteen male subjects (age = 56 ± 8 years; body mass index = 29 ± 1 kg/m 2 ; A1c = 5.7 ± 0.1%) were studied on two occasions, with a double-blind subcutaneous injection of EX (5 μg) or placebo (PLC) 30 minutes before a 75-g oral glucose tolerance test (OGTT). During OGTT, we measured hepatic (HGU) and adipose tissue (ATGU) glucose uptake with [ 18 F]2-fluoro-2-deoxy-D-glucose/positron emission tomography, lipolysis (RaGly) with [U- 2 H 5 ]-glycerol, oral glucose absorption (RaO) with [U- 13 C 6 ]-glucose, and hepatic glucose production (EGP) with [6,6- 2 H 2 ]-glucose. Adipo-IR and Hep-IR were calculated as (FFA 0-120min ) × (Ins 0-120min ) and (EGP 0-120min ) × (Ins 0-120min ), respectively. EX reduced RaO, resulting in reduced plasma glucose and insulin concentration from 0 to 120 minutes postglucose ingestion. EX decreased Hep-IR (197 ± 28 to 130 ± 37; P = 0.02) and increased HGU of orally administered glucose (23 ± 4 to 232 ± 89 [μmol/min/L]/[μmol/min/kg]; P = 0.003) despite lower insulin (23 ± 5 vs. 41 ± 5 mU/L; P < 0.02). EX enhanced insulin suppression of RaGly by decreasing Adipo-IR (23 ± 4 to 13 ± 3; P = 0.009). No significant effect of insulin was observed on ATGU (EX = 1.16 ± 0.15 vs. PLC = 1.36 ± 0.13 [μmol/min/L]/[μmol/min/kg]). Acute EX administration (1) improves Hep-IR, decreases EGP, and enhances HGU and (2) reduces Adipo-IR, improves the antilipolytic effect of insulin, and reduces plasma free fatty acid levels during OGTT. (Hepatology 2016;64:2028-2037). © 2016 by the American Association for the Study of Liver Diseases.

  10. Effect of canagliflozin on circulating active GLP-1 levels in patients with type 2 diabetes: a randomized trial.

    PubMed

    Takebayashi, Kohzo; Hara, Kenji; Terasawa, Tomoko; Naruse, Rika; Suetsugu, Mariko; Tsuchiya, Takafumi; Inukai, Toshihiko

    2017-09-30

    Canagliflozin has a robust inhibitory effect on sodium glucose transporter (SGLT)-2 and a mild inhibitory effect on SGLT1. The main purpose of this study was to investigate the effect of canagliflozin on circulating active glucagon-like peptide 1 (GLP-1) levels in patients with type 2 diabetes. Patients were randomly divided into a control group (n =15) and a canagliflozin-treated group (n =15). After hospitalization, the canagliflozin-treated group took 100 mg/day canagliflozin for the entire study, and after 3 days both groups took 20 mg/day teneligliptin for an additional 3 days. In a meal test, canagliflozin significantly decreased the area under curve (AUC) (0-120 min) for plasma glucose (PG) after 3 days when compared with that at baseline, and addition of teneligliptin to the canagliflozin-treated group further decreased it. A significant decrease in the AUC (0-120 min) for serum insulin by canagliflozin was obtained, but the addition of teneligliptin elevated the AUC, and thus abolished the significant difference from baseline. A significant increase in the AUC (0-120 min) of plasma active GLP-1 by canagliflozin-treatment compared with that at baseline was observed, and the addition of teneligliptin resulted in a further increase. However, canagliflozin-treatment did not change the AUC (0-120 min) of plasma active glucose-dependent insulinotropic peptide (GIP). In conclusions, canagliflozin-administration before meals decreased PG and serum insulin, and increased plasma active GLP-1 levels in patients with type 2 diabetes. Canagliflozin did not greatly influence plasma active GIP levels.

  11. Glucagon-like peptide-1 reduces pancreatic β-cell mass through hypothalamic neural pathways in high-fat diet-induced obese rats.

    PubMed

    Ando, Hisae; Gotoh, Koro; Fujiwara, Kansuke; Anai, Manabu; Chiba, Seiichi; Masaki, Takayuki; Kakuma, Tetsuya; Shibata, Hirotaka

    2017-07-17

    We examined whether glucagon-like peptide-1 (GLP-1) affects β-cell mass and proliferation through neural pathways, from hepatic afferent nerves to pancreatic efferent nerves via the central nervous system, in high-fat diet (HFD)-induced obese rats. The effects of chronic administration of GLP-1 (7-36) and liraglutide, a GLP-1 receptor agonist, on pancreatic morphological alterations, c-fos expression and brain-derived neurotrophic factor (BDNF) content in the hypothalamus, and glucose metabolism were investigated in HFD-induced obese rats that underwent hepatic afferent vagotomy (VgX) and/or pancreatic efferent sympathectomy (SpX). Chronic GLP-1 (7-36) administration to HFD-induced obese rats elevated c-fos expression and BDNF content in the hypothalamus, followed by a reduction in pancreatic β-cell hyperplasia and insulin content, thus resulting in improved glucose tolerance. These responses were abolished by VgX and SpX. Moreover, administration of liraglutide similarly activated the hypothalamic neural pathways, thus resulting in a more profound amelioration of glucose tolerance than native GLP-1 (7-36). These data suggest that GLP-1 normalizes the obesity-induced compensatory increase in β-cell mass and glucose intolerance through a neuronal relay system consisting of hepatic afferent nerves, the hypothalamus, and pancreatic efferent nerves.

  12. The FBPase Encoding Gene glpX Is Required for Gluconeogenesis, Bacterial Proliferation and Division In Vivo of Mycobacterium marinum

    PubMed Central

    Lyu, Liangdong; Wang, Chuan; Li, Yang; Gao, Qian; Yang, Chen

    2016-01-01

    Lipids have been identified as important carbon sources for Mycobacterium tuberculosis (Mtb) to utilize in vivo. Thus gluconeogenesis bears a key role for Mtb to survive and replicate in host. A rate-limiting enzyme of gluconeogenesis, fructose 1, 6-bisphosphatase (FBPase) is encoded by the gene glpX. The functions of glpX were studied in M. marinum, a closely related species to Mtb. The glpX deletion strain (ΔglpX) displayed altered gluconeogenesis, attenuated virulence, and altered bacterial proliferation. Metabolic profiles indicate an accumulation of the FBPase substrate, fructose 1, 6-bisphosphate (FBP) and altered gluconeogenic flux when ΔglpX is cultivated in a gluconeogenic carbon substrate, acetate. In both macrophages and zebrafish, the proliferation of ΔglpX was halted, resulting in dramatically attenuated virulence. Intracellular ΔglpX exhibited an elongated morphology, which was also observed when ΔglpX was grown in a gluconeogenic carbon source. This elongated morphology is also supported by the observation of unseparated multi-nucleoid cell, indicating that a complete mycobacterial division in vivo is correlated with intact gluconeogenesis. Together, our results indicate that glpX has essential functions in gluconeogenesis, and plays an indispensable role in bacterial proliferation in vivo and virulence of M. marinum. PMID:27233038

  13. The FBPase Encoding Gene glpX Is Required for Gluconeogenesis, Bacterial Proliferation and Division In Vivo of Mycobacterium marinum.

    PubMed

    Tong, Jingfeng; Meng, Lu; Wang, Xinwei; Liu, Lixia; Lyu, Liangdong; Wang, Chuan; Li, Yang; Gao, Qian; Yang, Chen; Niu, Chen

    2016-01-01

    Lipids have been identified as important carbon sources for Mycobacterium tuberculosis (Mtb) to utilize in vivo. Thus gluconeogenesis bears a key role for Mtb to survive and replicate in host. A rate-limiting enzyme of gluconeogenesis, fructose 1, 6-bisphosphatase (FBPase) is encoded by the gene glpX. The functions of glpX were studied in M. marinum, a closely related species to Mtb. The glpX deletion strain (ΔglpX) displayed altered gluconeogenesis, attenuated virulence, and altered bacterial proliferation. Metabolic profiles indicate an accumulation of the FBPase substrate, fructose 1, 6-bisphosphate (FBP) and altered gluconeogenic flux when ΔglpX is cultivated in a gluconeogenic carbon substrate, acetate. In both macrophages and zebrafish, the proliferation of ΔglpX was halted, resulting in dramatically attenuated virulence. Intracellular ΔglpX exhibited an elongated morphology, which was also observed when ΔglpX was grown in a gluconeogenic carbon source. This elongated morphology is also supported by the observation of unseparated multi-nucleoid cell, indicating that a complete mycobacterial division in vivo is correlated with intact gluconeogenesis. Together, our results indicate that glpX has essential functions in gluconeogenesis, and plays an indispensable role in bacterial proliferation in vivo and virulence of M. marinum.

  14. Benefits of an automated GLP final report preparation software solution.

    PubMed

    Elvebak, Larry E

    2011-07-01

    The final product of analytical laboratories performing US FDA-regulated (or GLP) method validation and bioanalysis studies is the final report. Although there are commercial-off-the-shelf (COTS) software/instrument systems available to laboratory managers to automate and manage almost every aspect of the instrumental and sample-handling processes of GLP studies, there are few software systems available to fully manage the GLP final report preparation process. This lack of appropriate COTS tools results in the implementation of rather Byzantine and manual processes to cobble together all the information needed to generate a GLP final report. The manual nature of these processes results in the need for several iterative quality control and quality assurance events to ensure data accuracy and report formatting. The industry is in need of a COTS solution that gives laboratory managers and study directors the ability to manage as many portions as possible of the GLP final report writing process and the ability to generate a GLP final report with the click of a button. This article describes the COTS software features needed to give laboratory managers and study directors such a solution.

  15. Metabolic effects of orally administered small-molecule agonists of GPR55 and GPR119 in multiple low-dose streptozotocin-induced diabetic and incretin-receptor-knockout mice.

    PubMed

    McKillop, Aine M; Moran, Brian M; Abdel-Wahab, Yasser H A; Gormley, Noella M; Flatt, Peter R

    2016-12-01

    Abnormal cannabidiol (Abn-CBD) and AS-1269574 are potent selective agonists for GPR55 and GPR119, respectively. The present study evaluated the actions and ability of these small-molecule agonists to counteract experimental diabetes in mice. Diabetes was induced in NIH Swiss mice by five consecutive daily intraperitoneal injections of 40 mg/(kg body weight) streptozotocin. Diabetic mice received daily oral administration of Abn-CBD or AS-1269574 (0.1 μmol/kg) or saline vehicle (0.9% wt/vol. NaCl) over 28 days. Body weight, food intake, fluid intake, plasma glucose, insulin, glucose tolerance, insulin release, lipid profile and pancreatic morphology were examined. Mechanism of action of agonists was assessed in acute studies using incretin-receptor-knockout mice. Abn-CBD and AS-1269574 decreased plasma glucose (20-26%, p < 0.05) and increased circulating insulin (47-48%, p < 0.05) by 10-28 days, compared with saline-treated diabetic controls. Food intake and polydipsia were reduced by both agonists (21-23%, p < 0.05 and 33-35%, p < 0.01, respectively). After 28 days of treatment, plasma glucagon concentrations were reduced (p < 0.01) and glucose tolerance was enhanced by 19-44% by Abn-CBD (p < 0.05 or p < 0.001) and AS-1269574 (p < 0.05 to p < 0.001). Plasma insulin responses were improved (p < 0.01) and insulin resistance was decreased (p < 0.05 or p < 0.01) in both Abn-CBD- and AS-1269574-treated groups. Triacylglycerols were decreased by 19% with Abn-CBD (p < 0.05) and 32% with AS-1269574 (p < 0.01) while total cholesterol was reduced by 17% (p < 0.01) and 15% (p < 0.05), respectively. Both agonists enhanced beta cell proliferation (p < 0.001) although islet area was unchanged. Acute studies in Gipr- and Glp1r-knockout mice revealed an important role for the glucagon-like peptide 1 (GLP-1) receptor in the actions of both agonists, with the glucose-lowering effects of Abn-CBD also partly

  16. Real-world effectiveness, adherence and persistence among patients with type 2 diabetes mellitus initiating dulaglutide treatment.

    PubMed

    Mody, Reema; Grabner, Michael; Yu, Maria; Turner, Ralph; Kwan, Anita Y M; York, Whitney; Fernández Landó, Laura

    2018-06-01

    To assess glycemic effectiveness, adherence and persistence within 6 months of treatment initiation with dulaglutide, a once weekly GLP-1 receptor agonist, in a US real-world setting. This retrospective claims analysis included adults (≥18 years) with T2DM from the HealthCore Integrated Research Database, who had HbA1c laboratory results around initiation and within 6 months after initiation. Glycemic control was assessed by change in HbA1c from pre-initiation to post-initiation. Patients were considered adherent if their proportion of days covered (PDC) was ≥0.80; persistence was measured as days of continuous therapy from initiation to 6 months after initiation with no gaps >45 days between fills. Of the 308 analyzed patients, the majority (n = 188; 61%) were adherent to dulaglutide (mean PDC 0.76; SD 0.26), with 115 patients (37%) discontinuing treatment. Mean persistence was 152 days/5 months. Mean HbA1c decreased from 8.49% (SD 1.70, median 8.20%) at baseline to 7.59% (SD 1.51, median 7.30%) at follow-up, corresponding to a mean HbA1c change of -0.90% (95% confidence interval [CI] -1.08 to -0.73; p < .01; median -0.70%). Patients who were adherent to or persistent with dulaglutide experienced larger reductions (-1.14% and -1.12% respectively), as did those without prior GLP-1 RA use (-1.03%). The proportion of patients with HbA1c <7% increased from 18% to 40%. Dulaglutide was associated with a significant decrease in HbA1c levels 6 months after treatment initiation. Patients who adhered to or persisted with dulaglutide therapy, or were naïve to GLP-1 RA use, experienced greater decreases in HbA1c levels.

  17. Unexpectedly increased anorexigenic postprandial responses of PYY and GLP-1 to fast ice cream consumption in adult patients with Prader-Willi syndrome.

    PubMed

    Rigamonti, A E; Bini, S; Grugni, G; Agosti, F; De Col, A; Mallone, M; Cella, S G; Sartorio, A

    2014-10-01

    The effect of eating rate on the release of anorexigenic gut peptides in Prader-Willi syndrome (PWS), a neurogenetic disorder clinically characterized by hyperphagia and excessive obesity, has not been investigated so far. Postprandial PYY and GLP-1 levels to fast (5 min) and slow (30 min) ice cream consumption were measured in PWS adult patients and age-matched patients with simple obesity and normal-weighted subjects. Visual analog scales (VASs) were used to evaluate the subjective feelings of hunger and satiety. Fast ice cream consumption stimulated GLP-1 release in normal subjects, a greater increase being observed with slow feeding. Fast or slow feeding did not change circulating levels of GLP-1 in obese patients, while, unexpectedly, fast feeding (but not slow feeding) stimulated GLP-1 release in PWS patients. Plasma PYY concentrations increased in all groups, irrespective of the eating rate. Slow feeding was more effective in stimulating PYY release in normal subjects, while fast feeding was more effective in PWS patients. Slow feeding evoked a lower hunger and higher satiety compared with fast feeding in normal subjects, this finding being not evident in obese patients. Unexpectedly, fast feeding evoked a lower hunger and higher satiety in PWS patients in comparison with slow feeding. Fast feeding leads to higher concentrations of anorexigenic gut peptides and favours satiety in PWS adult patients, this pattern being not evident in age-matched patients with simple obesity, thus suggesting the existence of a different pathophysiological substrate in these two clinical conditions. © 2013 John Wiley & Sons Ltd.

  18. Sucralose enhances GLP-1 release and lowers blood glucose in the presence of carbohydrate in healthy subjects but not in patients with type 2 diabetes.

    PubMed

    Temizkan, S; Deyneli, O; Yasar, M; Arpa, M; Gunes, M; Yazici, D; Sirikci, O; Haklar, G; Imeryuz, N; Yavuz, D G

    2015-02-01

    Artificial sweeteners were thought to be metabolically inactive, but after demonstrating that the gustatory mechanism was also localized in the small intestine, suspicions about the metabolic effects of artificial sweeteners have emerged. The objective of this study was to determine the effect of artificial sweeteners (aspartame and sucralose) on blood glucose, insulin, c-peptide and glucagon-like peptide-1 (GLP-1) levels. Eight newly diagnosed drug-naive type 2 diabetic patients (mean age 51.5±9.2 years; F/M: 4/4) and eight healthy subjects (mean age 45.0±4.1 years; F/M: 4/4) underwent 75 g oral glucose tolerance test (OGTT). During OGTT, glucose, insulin, c-peptide and GLP-1 were measured at 15- min intervals for 120 min. The OGTTs were performed at three settings on different days, where subjects were given 72 mg of aspartame and 24 mg of sucralose in 200 ml of water or 200 ml of water alone 15 min before OGTT in a single-blinded randomized order. In healthy subjects, the total area under the curve (AUC) of glucose was statistically significantly lower in the sucralose setting than in the water setting (P=0.002). There was no difference between the aspartame setting and the water setting (P=0.53). Total AUC of insulin and c-peptide was similar in aspartame, sucralose and water settings. Total AUC of GLP-1 was significantly higher in the sucralose setting than in the water setting (P=0.04). Total AUC values of glucose, insulin, c-peptide and GLP-1 were not statistically different in three settings in type 2 diabetic patients. Sucralose enhances GLP-1 release and lowers blood glucose in the presence of carbohydrate in healthy subjects but not in newly diagnosed type 2 diabetic patients.

  19. β cell membrane remodelling and procoagulant events occur in inflammation-driven insulin impairment: a GLP-1 receptor dependent and independent control.

    PubMed

    Gleizes, Céline; Kreutter, Guillaume; Abbas, Malak; Kassem, Mohamad; Constantinescu, Andrei Alexandru; Boisramé-Helms, Julie; Yver, Blandine; Toti, Florence; Kessler, Laurence

    2016-02-01

    Inflammation and hyperglycaemia are associated with a prothrombotic state. Cell-derived microparticles (MPs) are the conveyors of active procoagulant tissue factor (TF) and circulate at high concentration in diabetic patients. Liraglutide, a glucagon-like peptide (GLP)-1 analogue, is known to promote insulin secretion and β-cell preservation. In this in vitro study, we examined the link between insulin impairment, procoagulant activity and plasma membrane remodelling, under inflammatory conditions. Rin-m5f β-cell function, TF activity mediated by MPs and their modulation by 1 μM liraglutide were examined in a cell cross-talk model. Methyl-β-cyclodextrine (MCD), a cholesterol depletor, was used to evaluate the involvement of raft on TF activity, MP shedding and insulin secretion as well as Soluble N-éthylmaleimide-sensitive-factor Attachment protein Receptor (SNARE)-dependent exocytosis. Cytokines induced a two-fold increase in TF activity at MP surface that was counteracted by liraglutide. Microparticles prompted TF activity on the target cells and a two-fold decrease in insulin secretion via protein kinase A (PKA) and p38 signalling, that was also abolished by liraglutide. Large lipid raft clusters were formed in response to cytokines and liraglutide or MCD-treated cells showed similar patterns. Cells pre-treated by saturating concentration of the GLP-1r antagonist exendin (9-39), showed a partial abolishment of the liraglutide-driven insulin secretion and liraglutide-decreased TF activity. Measurement of caspase 3 cleavage and MP shedding confirmed the contribution of GLP-1r-dependent and -independent pathways. Our results confirm an integrative β-cell response to GLP-1 that targets receptor-mediated signalling and membrane remodelling pointing at the coupling of insulin secretion and inflammation-driven procoagulant events. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and

  20. Use and effectiveness of a fixed-ratio combination of insulin degludec/liraglutide (IDegLira) in a real-world population with type 2 diabetes: Results from a European, multicentre, retrospective chart review study.

    PubMed

    Price, Hermione; Blüher, Matthias; Prager, Rudolf; Phan, Tra-Mi; Thorsted, Brian L; Schultes, Bernd

    2018-04-01

    To describe the real-world use and effectiveness of IDegLira, a fixed-ratio combination of the basal insulin degludec, and the glucagon-like peptide-1 receptor agonist (GLP-1RA) liraglutide. This European, multicentre, retrospective chart review comprised adults (n = 611) with type 2 diabetes, who started IDegLira ≥6 months before data collection. Clinical characteristics were assessed at baseline (defined as the most recent recording during the 6 months before the first IDegLira prescription) and 3, 6, 9 and 12 months (± 45 days for each time point) after commencing IDegLira, where data were available. Baseline regimens included non-injectable medications (19%), basal insulin (19%), GLP-1RA (10%), free combination therapy (insulin/GLP-1RA, 24%) and multiple daily-dose insulin injections (MDI, 28%), all ± oral antidiabetic drugs. After 6 months, significant glycated haemoglobin (HbA1c) reductions were observed in patients overall and in all subgroups (-10 mmol/mol [-0.9%] overall; P < .0001), and a significant reduction in mean body weight (-0.7 kg; P < .05) was observed in patients overall and in patients receiving MDI (-2.4 kg; P < .0001). The mean IDegLira dose was 22, 30 and 32 dose steps at initiation, and at 6 and 12 months follow-up, respectively. In total, only 67 patients reached the maximum 50 dose steps, with most coming from the free combination therapy (n = 31) or MDI (n = 15) baseline regimen groups. Hypoglycaemia rates were reduced by 82% (rate ratio 0.18; P < .0001) in the 6-month period after vs before IDegLira initiation. Overall, a total of 12 patients experienced 15 events in the 6 months after IDegLira initiation. In real-world practice, after 6 months and at a moderate dose, IDegLira resulted in substantial reductions in HbA1c and body weight, with a reduced risk of hypoglycaemia. © 2017 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.

  1. Comparison of costs and outcomes of dapagliflozin with other glucose-lowering therapy classes added to metformin using a short-term cost-effectiveness model in the US setting.

    PubMed

    Chakravarty, Abhiroop; Rastogi, Mohini; Dhankhar, Praveen; Bell, Kelly F

    2018-05-01

    To compare 1-year costs and benefits of dapagliflozin (DAPA), a sodium-glucose cotransporter-2 (SGLT-2) inhibitor, with those of other treatments for type 2 diabetes (T2D), such as glucagon-like peptide-1 receptor agonists (GLP-1RAs), sulfonylureas (SUs), thiazolidinediones (TZDs), and dipeptidyl peptidase-4 inhibitors (DPP-4i), all combined with metformin. A short-term decision-analytic model with a 1-year time horizon was developed from a payer's perspective in the United States setting. Costs and benefits associated with four clinical end-points (glycated hemoglobin [A1C], body weight, systolic blood pressure [SBP], and risk of hypoglycemia) were evaluated in the analysis. The impact of DAPA and other glucose-lowering therapy classes on these clinical end-points was estimated from a network meta-analysis (NMA). Data for costs and quality-adjusted life-years (QALYs) associated with a per-unit change in these clinical end-points were taken from published literature. Drug prices were taken from an annual wholesale price list. All costs were inflation-adjusted to December 2016 costs using the medical care component of the consumer price index. Total costs (both medical and drug costs), total QALYs, and incremental cost-effectiveness ratios (ICERs) were estimated. Sensitivity analyses (SA) were performed to explore uncertainty in the inputs. To assess face validity, results from the short-term model were compared with long-term models published for these drugs. The total annual medical cost for DAPA was less than that for GLP-1RA ($186 less), DPP-4i ($1,142 less), SU ($2,474 less), and TZD ($1,640 less). Treatment with DAPA resulted in an average QALY gain of 0.0107, 0.0587, 0.1137, and 0.0715 per treated patient when compared with GLP-1RA, DPP-4i, SU, and TZD, respectively. ICERs for DAPA vs SU and TZD were $19,005 and $25,835, respectively. DAPA was a cost-saving option when compared with GLP-1RAs and DPP-4is. Among all four clinical end-points, change in weight

  2. The 2-monoacylglycerol moiety of dietary fat appears to be responsible for the fat-induced release of GLP-1 in humans.

    PubMed

    Mandøe, Mette J; Hansen, Katrine B; Hartmann, Bolette; Rehfeld, Jens F; Holst, Jens J; Hansen, Harald S

    2015-09-01

    Dietary triglycerides can, after digestion, stimulate the intestinal release of incretin hormones through activation of G protein-coupled receptor (GPR) 119 by 2-monoacylglycerol and by the activation of fatty acid receptors for long- and short-chain fatty acids. Medium-chain fatty acids do not stimulate the release of intestinal hormones. To dissect the mechanism of fat-induced glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) release in humans, we compared the effects of tributyrin (containing short-chain fatty acids; i.e., butyric acid), olive oil [containing long-chain fatty acids; e.g., oleic acid plus 2-oleoyl glycerol (2-OG)], and 1,3-dioctanoyl-2-oleoyl glycerol (C8-dietary oil), which is digested to form medium-chain fatty acids : i.e., octanoic acid : and 2-OG. In a randomized, single-blinded crossover study, 12 healthy white men [mean age: 24 y; BMI (in kg/m(2)): 22] were given the following 4 meals on 4 different days: 200 g carrots + 6.53 g tributyrin, 200 g carrots + 13.15 g C8-dietary oil, 200 g carrots + 19 g olive oil, or 200 g carrots. All of the lipids totaled 0.0216 mol. Main outcome measures were incremental areas under the curve for total GLP-1, GIP, and cholecystokinin (CCK) in plasma. C8-dietary oil and olive oil showed the same GLP-1 response [583 ± 101 and 538 ± 71 (pmol/L) × 120 min; P = 0.733], whereas the GIP response was higher for olive oil than for C8-dietary oil [3293 ± 404 and 1674 ± 270 (pmol/L) × 120 min; P = 0.002]. Tributyrin and carrots alone resulted in no increase in any of the measured hormones. Peptide YY (PYY) and neurotensin responses resembled those of GLP-1. Only olive oil stimulated CCK release. Under our study conditions, 2-OG and GPR119 activation can fully explain the olive oil-induced secretion of GLP-1, PYY, and neurotensin. In contrast, both oleic acid and 2-OG contributed to the GIP response. Dietary butyrate did not stimulate gut hormone secretion. Olive oil

  3. Effects of oat β-glucan consumption at breakfast on ad libitum eating, appetite, glycemia, insulinemia and GLP-1 concentrations in healthy subjects.

    PubMed

    Zaremba, Suzanne M M; Gow, Iain F; Drummond, Sandra; McCluskey, Jane T; Steinert, Robert E

    2018-06-18

    There is evidence that oat β-glucan lowers appetite and ad libitum eating; however, not all studies are consistent, and the underpinning mechanisms are not entirely understood. We investigated the effects of 4 g high molecular weight (MW) oat β-glucan on ad libitum eating, subjective appetite, glycemia, insulinemia and plasma GLP-1 responses in 33 normal-weight subjects (22 female/11 male, mean age (y): 26.9 ± 1.0, BMI (kg/m 2 ): 23.5 ± 0.4). The study followed a randomised double-blind, cross-over design with subjects fed two test breakfasts with and without oat β-glucan followed by an ad libitum test meal on two different days. Blood samples and ratings for subjective appetite were collected postprandially at regular time intervals. Oat β-glucan increased feelings of fullness (p = 0.048) and satiety (p = 0.034), but did not affect energy and amount eaten at the ad libitum test meal. There was a treatment by time interaction for plasma GLP-1, plasma insulin and blood glucose. GLP-1 was significantly reduced at 90 min (p = 0.021), blood glucose at 30 min (p = 0.008) and plasma insulin at 30 and 60 min (p = 0.002 and 0.017, respectively) following the oat β-glucan breakfast when compared with the control breakfast. Four grams of high MW oat β-glucan lowers appetite but not ad libitum eating and beneficially modulates postprandial glycaemia, it does however, not increase plasma GLP-1 secretion. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. REVIEW: Role of cyclic AMP signaling in the production and function of the incretin hormone glucagon-like peptide-1

    NASA Astrophysics Data System (ADS)

    Yu, Zhiwen; Jin, Tianru

    2008-01-01

    Pancreatic cells express the proglucagon gene (gcg) and thereby produce the peptide hormone glucagon, which stimulates hepatic glucose production and thereby increases blood glucose levels. The same gcg gene is also expressed in the intestinal endocrine L cells and certain neural cells in the brain. In the gut, gcg expression leads to the production of glucagon-like peptide-1 (GLP-1). This incretin hormone stimulates insulin secretion when blood glucose level is high. In addition, GLP-1 stimulates pancreatic cell proliferation, inhibits cell apoptosis, and has been utilized in the trans-differentiation of insulin producing cells. Today, a long-term effective GLP-1 receptor agonist has been developed as a drug in treating diabetes and potentially other metabolic disorders. Extensive investigations have shown that the expression of gcg and the production of GLP-1 can be activated by the elevation of the second messenger cyclic AMP (cAMP). Recent studies suggest that in addition to protein kinase A (PKA), exchange protein activated by cAMP (Epac), another effector of cAMP signaling, and the crosstalk between PKA and Wnt signaling pathway, are also involved in cAMP-stimulated gcg expression and GLP-1 production. Furthermore, functions of GLP-1 in pancreatic cells are mainly mediated by cAMP-PKA, cAMP-Epac and Wnt signaling pathways as well.

  5. Postmeal increment in intact glucagon-like peptide 1 level, but not intact glucose-dependent insulinotropic polypeptide levels, is inversely associated with metabolic syndrome in patients with type 2 diabetes.

    PubMed

    Yoo, Soyeon; Yang, Eun-Jin; Lee, Sang Ah; Koh, Gwanpyo

    2018-02-01

    Metabolic syndrome increases the risk of cardiovascular disease. Recently glucagon-like peptide 1 (GLP-1) agonists proved to be effective in preventing cardiovascular disease (CVD) in patients with type 2 diabetes. We investigated the association of blood incretin levels with metabolic syndrome in patients with type 2 diabetes. This is a cross-sectional study involving 334 people with type 2 diabetes. Intact GLP-1 (iGLP-1) and intact glucose-dependent insulinotropic polypeptide (iGIP) levels were measured in a fasted state and 30 min after ingestion of a standard mixed meal. Metabolic syndrome was diagnosed based on the criteria of the International Diabetes Federation. Two hundred twenty-five (69%) of the subjects have metabolic syndrome. The fasting iGLP-1 level was no different between groups. Thirty-min postprandial iGLP-1 was non-significantly lower in the subjects who had metabolic syndrome. Incremental iGLP-1 (ΔiGLP-1, the difference between 30-min postmeal and fasting iGLP-1 levels) was significantly lower in those with metabolic syndrome. There were no significant differences in fasting iGIP, postprandial iGIP, and ΔiGIP between groups. The ΔiGLP-1, but not ΔiGIP levels decreased significantly as the number of metabolic syndrome components increased. In hierarchical logistic regression analysis, the ΔiGLP-1 level was found to be a significant contributor to metabolic syndrome even after adjusting for other covariates. Taken together, the iGLP-1 increment in the 30 min after meal ingestion is inversely associated with metabolic syndrome in patients with type 2 diabetes. This suggests that postmeal iGLP-1 increment could be useful in assessing cardiovascular risk in type 2 diabetes.

  6. D1 receptor agonist improves sleep-wake parameters in experimental parkinsonism.

    PubMed

    Hyacinthe, Carole; Barraud, Quentin; Tison, François; Bezard, Erwan; Ghorayeb, Imad

    2014-03-01

    Both excessive daytime sleepiness (EDS) and rapid eye movement (REM) sleep deregulation are part of Parkinson's disease (PD) non-motor symptoms and may complicate dopamine replacement therapy. We report here that dopamine agonists act differentially on sleep architecture in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine macaque monkey. Continuous sleep and wake electroencephalographic monitoring revealed no effect of the selective dopamine D2 receptor agonist quinpirole on EDS, whereas the selective dopamine D1 receptor agonist SKF38393 efficiently alleviated EDS and restored REM sleep to baseline values. The present results question the relevance of abandoning D1 receptor agonist treatment in PD as it might actually improve sleep-related disorders. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. IL-1 receptor-antagonist (IL-1Ra) knockout mice show anxiety-like behavior by aging.

    PubMed

    Wakabayashi, Chisato; Numakawa, Tadahiro; Odaka, Haruki; Ooshima, Yoshiko; Kiyama, Yuji; Manabe, Toshiya; Kunugi, Hiroshi; Iwakura, Yoichiro

    2015-07-10

    Interleukin 1 (IL-1) plays a critical role in stress responses, and its mRNA is induced in the brain by restraint stress. Previously, we reported that IL-1 receptor antagonist (IL-1Ra) knockout (KO) mice, which lacked IL-1Ra molecules that antagonize the IL-1 receptor, showed anti-depression-like behavior via adrenergic modulation at the age of 8 weeks. Here, we report that IL-1Ra KO mice display an anxiety-like phenotype that is induced spontaneously by aging in the elevated plus-maze (EPM) test. This anxiety-like phenotype was improved by the administration of diazepam. The expression of the anxiety-related molecule glucocorticoid receptor (GR) was significantly reduced in 20-week-old but not in 11-week-old IL-1Ra KO mice compared to wild-type (WT) littermates. The expression of the mineralocorticoid receptor (MR) was not altered between IL-1Ra KO mice and WT littermates at either 11 or 20 weeks old. Analysis of monoamine concentration in the hippocampus revealed that tryptophan, the serotonin metabolite 5-hydroxyindole acetic acid (5-HIAA), and the dopamine metabolite homovanillic acid (HVA) were significantly increased in 20-week-old IL-1Ra KO mice compared to littermate WT mice. These findings strongly suggest that the anxiety-like behavior observed in older mice was caused by the complicated alteration of monoamine metabolism and/or GR expression in the hippocampus. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. A novel GLP-1/GIP/Gcg triagonist reduces cognitive deficits and pathology in the 3xTg mouse model of Alzheimer's disease.

    PubMed

    Li, Tian; Jiao, Juan-Juan; Hölscher, Christian; Wu, Mei-Na; Zhang, Jun; Tong, Jia-Qing; Dong, Xue-Fan; Qu, Xue-Song; Cao, Yue; Cai, Hong-Yan; Su, Qiang; Qi, Jin-Shun

    2018-05-01

    Type 2 diabetes mellitus (T2DM) is an important risk factor for Alzheimer's disease (AD). Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have been identified to be effective in T2DM treatment and neuroprotection. In this study, we further explored the effects of a novel unimolecular GLP-1/GIP/Gcg triagonist on the cognitive behavior and cerebral pathology in the 7-month-old triple transgenic mouse model of AD (3xTg-AD), and investigated its possible electrophysiological and molecular mechanisms. After chronic administration of the GLP-1/GIP/Gcg triagonist (10 nmol/kg bodyweight, once daily, i.p.) for 30 days, open field, Y maze and Morris water maze tests were performed, followed by in vivo electrophysiological recording, immunofluorescence and Western blotting experiments. We found that the chronic treatment with the triagonist could improve long-term spatial memory of 3xTg-AD mice in Morris water maze, as well as the working memory in Y maze task. The triagonist also alleviated the suppression of long-term potentiation (LTP) in the CA1 region of hippocampus. In addition, the triagonist significantly reduced hippocampal pathological damages, including amyloid-β (Aβ) and phosphorylated tau aggregates, and upregulated the expression levels of S133 p-CREB, T286 p-CAMKII and S9 p-GSK3β in the hippocampus of the 3xTg-AD mice. These results demonstrate for the first time that the novel GLP-1/GIP/Gcg triagonist is efficacious in ameliorating cognitive deficits and pathological damages of 3xTg-AD mice, suggesting that the triagonist might be potentially beneficial in the treatment of AD. © 2018 Wiley Periodicals, Inc.

  9. Albiglutide for the treatment of type 2 diabetes mellitus: An integrated safety analysis of the HARMONY phase 3 trials.

    PubMed

    Ahrén, Bo; Carr, Molly C; Murphy, Karen; Perkins, Christopher; Rendell, Marc; Mallory, Jason; Wilson, Timothy; Johnson, Susan

    2017-04-01

    Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) stimulate the incretin system and lower glycaemic parameters in type 2 diabetes mellitus (T2DM). This analysis of clinical studies of up to 3years evaluated the safety of albiglutide, a GLP-1 RA, in people with T2DM. Integrated safety analysis included seven phase-3 T2DM studies of albiglutide compared with placebo and/or active comparators (a dipeptidyl peptidase-4 inhibitor, GLP-1 RA, insulin, sulphonylurea, and thiazolidinedione). Studies of 32months (HARMONY 7), 1year (HARMONY 6), and 3years (HARMONY 1-5), reported similar rates of adverse events (AEs) (84.8%, 82.3%), and serious AEs (13.1%, 12.9%) between albiglutide and all comparators, respectively. AEs that did not differ between the groups included symptomatic or severe hypoglycaemia as well as nausea (12.0%, 11.3%) and vomiting (5.3%, 4.7%) for albiglutide and all comparators, respectively. According to the Medical Dictionary for Regulatory Activities preferred terms, only diarrhoea (13.7%, 9.9%), injection-site reaction (9.0%, 2.0%), and peripheral oedema (4.5%, 6.8%) had at least 2% difference between the albiglutide and all-comparator groups. In a similar integrated analysis, pancreatitis occurred more often with albiglutide (0.3%, 0.1%). Renal and cardiac function did not differ between the two groups. In an integrated analysis of seven phase 3 clinical trials, albiglutide-treated patients experienced frequencies of AEs (including cardiovascular and renal) similar to the all-comparators group treated with other T2DM medications or placebo. Albiglutide treatment was associated with higher rates of diarrhoea and injection-site reactions, but not increased nausea and vomiting, versus all comparators. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Hindbrain leptin and glucagon-like-peptide-1 receptor signaling interact to suppress food intake in an additive fashion

    PubMed Central

    Zhao, Shiru; Kanoski, Scott E.; Yan, Jianqun; Grill, Harvey J.; Hayes, Matthew R.

    2011-01-01

    Background The physiological control of feeding behavior involves modulation of the intake inhibitory effects of gastrointestinal satiation signaling via endogenous hindbrain leptin receptor (LepR) and glucagon-like-peptide-1 receptor (GLP-1R) activation. Design and Results Using a variety of dose-combinations of hindbrain delivered (4th icv) leptin and the GLP-1R agonist exendin-4, experiments demonstrate that hindbrain LepR and GLP-1R signaling interact to control food intake and body weight in an additive fashion. In addition, the maximum intake suppressive response that could be achieved by 4th icv leptin alone in non-obese rats (~33%) was shown to be further suppressed when exendin-4 was co-administered. Importantly, it was determined that the interaction between hindbrain LepR signaling and GLP-1R signaling is relevant to endogenous food intake control, as hindbrain GLP-1R blockade by the selective antagonist exendin-(9–39) attenuated the intake inhibitory effects of hindbrain leptin delivery. Conclusions Collectively, the findings reported here show that hindbrain LepR and GLP-1R activation interact in at least an additive fashion to control food intake and body weight. As evidence is accumulating that combination pharmacotherapies offer greater sustained food intake and body weight suppression in obese individuals when compared to mono-drug therapies or lifestyle modifications alone, these findings highlight the need for further examination of combined CNS GLP-1R and LepR signaling as a potential drug target for obesity treatment. PMID:22249232

  11. A Brief History of IL-1 and IL-1 Ra in Rheumatology.

    PubMed

    Dayer, Jean-Michel; Oliviero, Francesca; Punzi, Leonardo

    2017-01-01

    The history of what, in 1979, was called interleukin-1 (IL-1), orchestrator of leukocyte inter-communication, began many years before then, initially by the observation of fever induction via the endogenous pyrogen (EP) (1974) and then in rheumatology on the role in tissue destruction in rheumatoid diseases via the induction of collagenase and PGE 2 in human synovial cells by a mononuclear cell factor (MCF) (1977). Since then, the family has exploded to presently 11 members as well as many membrane-bound and soluble receptor forms. The discovery of a natural Interleukin-1 receptor antagonist (IL-1Ra) in human biological fluids has highlighted the importance of IL-1 and IL-1Ra in human diseases. Evidence delineating its role in autoinflammatory syndromes and the elucidation of the macromolecular complex referred to as "inflammasome" have been instrumental to our understanding of the link with IL-1. At present, the IL-1blockade as therapeutic approach is crucial for many hereditary autoinflammatory diseases, as well as for adult-onset Still's disease, crystal-induced arthropathies, certain skin diseases including neutrophil-triggered skin diseases, Behçet's disease and deficiency of IL-1Ra and other rare fever syndromes. Its role is only marginally important in rheumatoid arthritis and is still under debate with regard to osteoarthritis, type 2 diabetes mellitus, cardiovascular diseases and cancer. This brief historical review focuses on some aspects of IL-1, mainly IL-1β and IL-Ra, in rheumatology. There are many excellent reviews focusing on the IL-1 family in general or with regard to specific diseases or biological discoveries.

  12. Ghrelin, CCK, GLP-1, and PYY(3-36): Secretory Controls and Physiological Roles in Eating and Glycemia in Health, Obesity, and After RYGB.

    PubMed

    Steinert, Robert E; Feinle-Bisset, Christine; Asarian, Lori; Horowitz, Michael; Beglinger, Christoph; Geary, Nori

    2017-01-01

    The efficacy of Roux-en-Y gastric-bypass (RYGB) and other bariatric surgeries in the management of obesity and type 2 diabetes mellitus and novel developments in gastrointestinal (GI) endocrinology have renewed interest in the roles of GI hormones in the control of eating, meal-related glycemia, and obesity. Here we review the nutrient-sensing mechanisms that control the secretion of four of these hormones, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide tyrosine tyrosine [PYY(3-36)], and their contributions to the controls of GI motor function, food intake, and meal-related increases in glycemia in healthy-weight and obese persons, as well as in RYGB patients. Their physiological roles as classical endocrine and as locally acting signals are discussed. Gastric emptying, the detection of specific digestive products by small intestinal enteroendocrine cells, and synergistic interactions among different GI loci all contribute to the secretion of ghrelin, CCK, GLP-1, and PYY(3-36). While CCK has been fully established as an endogenous endocrine control of eating in healthy-weight persons, the roles of all four hormones in eating in obese persons and following RYGB are uncertain. Similarly, only GLP-1 clearly contributes to the endocrine control of meal-related glycemia. It is likely that local signaling is involved in these hormones' actions, but methods to determine the physiological status of local signaling effects are lacking. Further research and fresh approaches are required to better understand ghrelin, CCK, GLP-1, and PYY(3-36) physiology; their roles in obesity and bariatric surgery; and their therapeutic potentials. Copyright © 2017 the American Physiological Society.

  13. Pancreatic cancer-derived exosomes suppress the production of GIP and GLP-1 from STC-1 cells in vitro by down-regulating the PCSK1/3.

    PubMed

    Zhang, Yuefeng; Huang, Shifei; Li, Pengping; Chen, Qing; Li, Yongzhou; Zhou, Yizhao; Wang, Lantian; Kang, Muxing; Zhang, Bo; Yang, Bin; Wu, Yulian

    2018-05-22

    One hallmark of pancreatic cancer (PC) is the high prevalence of pancreatic cancer-associated diabetes mellitus (PC-DM), but the mechanisms remain to be elucidated. Patients with PC who are diagnosed with new-onset diabetes/prediabetes have recently been shown to display significantly lower levels of glucose-dependent insulinotropic peptide (GIP) secreted mainly by enteroendocrine cells. We hypothesized that PC-derived exosomes are responsible for the decreased levels of incretins in patients with PC-DM. In this study, exosomes were successfully isolated from PANC-1, MIA PaCa-2 and SW620 cells and characterized. Only the exosomes from MIA PaCa-2 cells (Exo-Mia) reduce the production of GIP and glucagon-like peptide-1 (GLP-1) from STC-1 cells in vitro in a concentration- and time-dependent manner. Moreover, Exo-Mia increased the levels of the Gip and proglucagon mRNAs and decreased the expression of proprotein convertase subtilisin/kexin type 1/3 (PCSK1/3), which is responsible for the post-translational processing of Gip and proglucagon. Furthermore, differentially expressed exosomal miRNAs (miR-6796-3p, miR-6763-5p, miR-4750-3p and miR-197-3p) were identified and considered to be responsible for the inhibitory effects on GIP and GLP-1 production. To further determine the approach of cancer-derived exosomes reaching enteroendocrine cells, we analyzed the uptake and distribution of exosomes in animal model. It was observed that exosomes infused into the intestinal cavity were more easily internalized by the intestinal epithelium than exosomes injected into blood. In conclusion, pancreatic cancer-derived exosomes (Exo-Mia) suppress the synthesis of GIP and GLP-1 from STC-1 cells in vitro by down-regulating the PCSK1/3. Moreover, it may be the pancreatic juice that transport cancer-derived exosomes to target cells (K and L cells) in the gut. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. The Bro1-Domain Protein, EGO-2, Promotes Notch Signaling in Caenorhabditis elegans

    PubMed Central

    Liu, Ying; Maine, Eleanor M.

    2007-01-01

    In Caenorhabditis elegans, as in other animals, Notch-type signaling mediates numerous inductive events during development. The mechanism of Notch-type signaling involves proteolytic cleavage of the receptor and subsequent transport of the receptor intracellular domain to the nucleus, where it acts as a transcriptional regulator. Notch-type signaling activity is modulated by post-translational modifications and endocytosis of ligand and receptor. We previously identified the ego-2 (enhancer of glp-1) gene as a positive regulator of germline proliferation that interacts genetically with the GLP-1/Notch signaling pathway in the germline. Here, we show that ego-2 positively regulates signaling in various tissues via both GLP-1 and the second C. elegans Notch-type receptor, LIN-12. ego-2 activity also promotes aspects of development not known to require GLP-1 or LIN-12. The EGO-2 protein contains a Bro1 domain, which is known in other systems to localize to certain endosomal compartments. EGO-2 activity in the soma promotes GLP-1 signaling in the germline, consistent with a role for EGO-2 in production of active ligand. Another C. elegans Bro1-domain protein, ALX-1, is known to interact physically with LIN-12/Notch. We document a complex phenotypic interaction between ego-2 and alx-1, consistent with their relationship being antagonistic with respect to some developmental processes and agonistic with respect to others. PMID:17603118

  15. Genetically encoded photocross-linkers determine the biological binding site of exendin-4 peptide in the N-terminal domain of the intact human glucagon-like peptide-1 receptor (GLP-1R)

    PubMed Central

    Koole, Cassandra; Reynolds, Christopher A.; Mobarec, Juan C.; Hick, Caroline; Sexton, Patrick M.; Sakmar, Thomas P.

    2017-01-01

    The glucagon-like peptide-1 receptor (GLP-1R) is a key therapeutic target in the management of type II diabetes mellitus, with actions including regulation of insulin biosynthesis and secretion, promotion of satiety, and preservation of β-cell mass. Like most class B G protein-coupled receptors (GPCRs), there is limited knowledge linking biological activity of the GLP-1R with the molecular structure of an intact, full-length, and functional receptor·ligand complex. In this study, we have utilized genetic code expansion to site-specifically incorporate the photoactive amino acid p-azido-l-phenylalanine (azF) into N-terminal residues of a full-length functional human GLP-1R in mammalian cells. UV-mediated photolysis of azF was then carried out to induce targeted photocross-linking to determine the proximity of the azido group in the mutant receptor with the peptide exendin-4. Cross-linking data were compared directly with the crystal structure of the isolated N-terminal extracellular domain of the GLP-1R in complex with exendin(9–39), revealing both similarities as well as distinct differences in the mode of interaction. Generation of a molecular model to accommodate the photocross-linking constraints highlights the potential influence of environmental conditions on the conformation of the receptor·peptide complex, including folding dynamics of the peptide and formation of dimeric and higher order oligomeric receptor multimers. These data demonstrate that crystal structures of isolated receptor regions may not give a complete reflection of peptide/receptor interactions and should be combined with additional experimental constraints to reveal peptide/receptor interactions occurring in the dynamic, native, and full-length receptor state. PMID:28283573

  16. Lipid Raft-dependent Glucagon-like Peptide-2 Receptor Trafficking Occurs Independently of Agonist-induced Desensitization

    PubMed Central

    Estall, Jennifer L.; Yusta, Bernardo; Drucker, Daniel J.

    2004-01-01

    The intestinotrophic and cytoprotective actions of glucagon-like peptide-2 (GLP-2) are mediated by the GLP-2 receptor (GLP-2R), a member of the class II glucagon-secretin G protein-coupled receptor superfamily. Although native GLP-2 exhibits a short circulating half-life, long-acting degradation-resistant GLP-2 analogues are being evaluated for therapeutic use in human subjects. Accordingly, we examined the mechanisms regulating signaling, internalization, and trafficking of the GLP-2R to identify determinants of receptor activation and desensitization. Heterologous cells expressing the transfected rat or human GLP-2R exhibited a rapid, dose-dependent, and prolonged desensitization of the GLP-2–stimulated cAMP response and a sustained GLP-2–induced decrease in levels of cell surface receptor. Surprisingly, inhibitors of clathrin-dependent endocytosis failed to significantly decrease GLP-2R internalization, whereas cholesterol sequestration inhibited ligand-induced receptor internalization and potentiated homologous desensitization. The hGLP-2R localized to both Triton X-100–soluble and –insoluble (lipid raft) cellular fractions and colocalized transiently with the lipid raft marker caveolin-1. Although GLP-2R endocytosis was dependent on lipid raft integrity, the receptor transiently associated with green fluorescent protein tagged-early endosome antigen 1–positive vesicles and inhibitors of endosomal acidification attenuated the reappearance of the GLP-2R on the cell surface. Our data demonstrate that GLP-2R desensitization and raft-dependent trafficking represent distinct and independent cellular mechanisms and provide new evidence implicating the importance of a clathrin- and dynamin-independent, lipid raft-dependent pathway for homologous G protein-coupled receptor internalization. PMID:15169869

  17. How to fight obesity with antidiabetic drugs: targeting gut or kidney?

    PubMed

    Baretić, M; Troskot, R

    2015-03-01

    The increased prevalence of type 2 diabetes follows the increased prevalence of obesity. Both diseases share common pathophysiological pathways; obesity is in most cases the first step, whereas diabetes is the second one. Weight gain occurs during the treatment of diabetes with drugs causing endogenous or exogenous hyperinsulinemia. Insulin and sulfonylurea are making patients more obese and more insulin resistant. Glucagon-like peptide-1 receptor agonists (GLP-1 agonists) and sodium/glucose cotransporter 2 inhibitors (SGLT2 inhibitors) are antidiabetic drugs with weight loss property. GLP-1 agonists mimic an incretin action. They release insulin after a meal during hyperglycemia and suppress glucagon. The weight loss effect is a consequence of central action increased satiety. Some of GLP-1 agonists weight loss is a result of decelerated gastric emptying rate. SGLT2 inhibitors block sodium glucose cotransporter in proximal tubule brush border and produce glucose excretion with urinary loss. Urinary glucose leak results in calories and weight loss. Even a modest weight loss has positive outcome on metabolic features of diabetic patient; such drugs have important role in treatment of type 2 diabetic patients. However, there are some still unresolved questions. The weight loss they produce is modest. Those drugs are expensive and not available to many diabetic patients, they are significantly more expensive compared to "traditional" hypoglycemic drugs. The hypoglycemic endpoint of GLP-1 agonists and SGLT2 inhibitors often requires adding another antidiabetic drug. The most radical and most effective therapy of type 2 diabetes and obesity is bariatric surgery having significant number of diabetes remission.

  18. GLP2: an underestimated signal for improving glycaemic control and insulin sensitivity.

    PubMed

    Amato, Antonella; Baldassano, Sara; Mulè, Flavia

    2016-05-01

    Glucagon-like peptide 2 (GLP2) is a proglucagon-derived peptide produced by intestinal enteroendocrine L-cells and by a discrete population of neurons in the brainstem, which projects mainly to the hypothalamus. The main biological actions of GLP2 are related to the regulation of energy absorption and maintenance of mucosal morphology, function and integrity of the intestine; however, recent experimental data suggest that GLP2 exerts beneficial effects on glucose metabolism, especially in conditions related to increased uptake of energy, such as obesity, at least in the animal model. Indeed, mice lacking GLP2 receptor selectively in hypothalamic neurons that express proopiomelanocortin show impaired postprandial glucose tolerance and hepatic insulin resistance (by increased gluconeogenesis). Moreover, GLP2 acts as a beneficial factor for glucose metabolism in mice with high-fat diet-induced obesity. Thus, the aim of this review is to update and summarize current knowledge about the role of GLP2 in the control of glucose homeostasis and to discuss how this molecule could exert protective effects against the onset of related obesity type 2 diabetes. © 2016 Society for Endocrinology.

  19. Effects of topical sphingosine-1-phosphate 1 receptor agonist on corneal allograft in mice.

    PubMed

    Jia, Liang; Liu, Yong; Wang, Liqiang; Zhu, Jing; Huang, Yifei

    2014-04-01

    The aim of this study was to compare the antirejection effects of topical selective sphingosine-1-phosphate 1 receptor (S1P1) agonist and cyclosporine A (CsA) on the acceptance of a transplanted, allogeneic cornea graft in a murine animal model. Fifty-six BALB/c mice were randomly divided into 4 groups. All the mice received corneal grafts from 28 C57BL/6 donors. Experimental recipients were treated with 0.25%, 0.5% S1P1 agonist suspension eye drops or 1% CsA eye drops 4 times a day after the corneal graft was performed. Controls received no treatment. The corneal grafts were imaged and evaluated with clinical scoring. The excised corneal sections 14 days after transplantation were stained using hematoxylin-eosin for histopathological evaluation. CD86+ and MHC-II+ dendritic cells in corneal samples were identified by immunohistochemical staining. The expression of mRNA in the cornea was evaluated using real-time quantitative PCR for interleukin-2, interferon-gamma, and cytotoxic T-lymphocyte antigen 4. Corneal graft survival was prolonged by treatment with 0.5% S1P1 agonist and 1% CsA (P < 0.01, respectively) when compared with that in the control in clinical scoring. In addition, topical application of 0.5% S1P1 increased the cytotoxic T-lymphocyte antigen 4 mRNA expression of the corneal grafts. There were significant differences observed with 0.5% S1P1 and agonist 1% CsA (P < 0.01, respectively) when compared with the values of the control group in histology scoring. Topical 0.5% S1P1 agonist is as effective as 1% CsA, and both can effectively prolong the survival of corneal allografts in mice.

  20. De-repression of RaRF-mediated RAR repression by adenovirus E1A in the nucleolus.

    PubMed

    Um, Soo-Jong; Youn, Hye Sook; Kim, Eun-Joo

    2014-02-21

    Transcriptional activity of the retinoic acid receptor (RAR) is regulated by diverse binding partners, including classical corepressors and coactivators, in response to its ligand retinoic acid (RA). Recently, we identified a novel corepressor of RAR called the retinoic acid resistance factor (RaRF) (manuscript submitted). Here, we report how adenovirus E1A stimulates RAR activity by associating with RaRF. Based on immunoprecipitation (IP) assays, E1A interacts with RaRF through the conserved region 2 (CR2), which is also responsible for pRb binding. The first coiled-coil domain of RaRF was sufficient for this interaction. An in vitro glutathione-S-transferase (GST) pull-down assay was used to confirm the direct interaction between E1A and RaRF. Further fluorescence microscopy indicated that E1A and RaRF were located in the nucleoplasm and nucleolus, respectively. However, RaRF overexpression promoted nucleolar translocation of E1A from the nucleoplasm. Both the RA-dependent interaction of RAR with RaRF and RAR translocation to the nucleolus were disrupted by E1A. RaRF-mediated RAR repression was impaired by wild-type E1A, but not by the RaRF binding-defective E1A mutant. Taken together, our data suggest that E1A is sequestered to the nucleolus by RaRF through a specific interaction, thereby leaving RAR in the nucleoplasm for transcriptional activation. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. The application of capillary microsampling in GLP toxicology studies.

    PubMed

    Verhaeghe, Tom; Dillen, Lieve; Stieltjes, Hans; Zwart, Loeckie de; Feyen, Bianca; Diels, Luc; Vroman, Ann; Timmerman, Philip

    2017-04-01

    Capillary microsampling (CMS) to collect microplasma volumes is gradually replacing traditional, larger volume sampling from rats in GLP toxicology studies. About 32 µl of blood is collected with a capillary, processed to plasma and stored in a 10- or 4-µl capillary which is washed out further downstream in the laboratory. CMS has been standardized with respect to materials, assay validation experiments and application for sample analysis. The implementation of CMS has resulted in blood volume reductions in the rat from 300 to 32 µl per time point and the elimination of toxicokinetic satellite groups in the majority of the rat GLP toxicology studies. The technique has been successfully applied in 26 GLP studies for 12 different projects thus far.

  2. Adenosine-A1 Receptor Agonist Induced Hyperalgesic Priming Type II

    PubMed Central

    Araldi, Dioneia; Ferrari, Luiz F.; Levine, Jon D.

    2016-01-01

    We have recently shown that repeated exposure of the peripheral terminal of the primary afferent nociceptor to the mu-opioid receptor (MOR) agonist DAMGO ([D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin acetate salt) induces a model of the transition to chronic pain that we have termed Type II hyperalgesic priming. Similar to Type I hyperalgesic priming, there is a markedly prolonged response to subsequent administration of proalgesic cytokines, prototypically prostaglandin E2 (PGE2). However, Type II hyperalgesic priming differs from Type I in being rapidly induced, protein kinase A (PKA), rather than PKCε dependent, not reversed by a protein translation inhibitor, occurring in female as well as in male rats, and isolectin B4-negative neuron dependent. We report that as with the repeated injection of a MOR agonist, the repeated administration of an agonist at the A1-adenosine receptor, also a Gi-protein coupled receptor, N6-Cyclopentyladenosine (CPA), also produces priming similar to DAMGO-induced Type II hyperalgesic priming. In this study we demonstrate that priming induced by repeated exposure to this A1-adenosine receptor agonist shares the same mechanisms as MOR-agonist induced priming. However, the prolongation of PGE2 hyperalgesia induced by repeated administration of CPA depends on G-protein αi subunit activation, differently from DAMGO-induced Type II priming, in which it depends on the β/γ subunit. These data implicate a novel form of Gi-protein signaling pathway in the Type II hyperalgesic priming induced by repeated administration of an agonist at A1-adenosine receptor to the peripheral terminal of the nociceptor. PMID:26588695

  3. Discovery of Potent and Selective Inhibitors for G9a-Like Protein (GLP) Lysine Methyltransferase

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xiong, Yan; Li, Fengling; Babault, Nicolas

    G9a-like protein (GLP) and G9a are highly homologous protein lysine methyltransferases (PKMTs) sharing approximately 80% sequence identity in their catalytic domains. GLP and G9a form a heterodimer complex and catalyze mono- and dimethylation of histone H3 lysine 9 and nonhistone substrates. Although they are closely related, GLP and G9a possess distinct physiological and pathophysiological functions. Thus, GLP or G9a selective small-molecule inhibitors are useful tools to dissect their distinct biological functions. We previously reported potent and selective G9a/GLP dual inhibitors including UNC0638 and UNC0642. Here we report the discovery of potent and selective GLP inhibitors including 4 (MS0124) and 18more » (MS012), which are >30-fold and 140-fold selective for GLP over G9a and other methyltransferases, respectively. The cocrystal structures of GLP and G9a in the complex with either 4 or 18 displayed virtually identical binding modes and interactions, highlighting the challenges in structure-based design of selective inhibitors for either enzyme.« less

  4. LARETH-25 and β-CD improve central transitivity and central pharmacological effect of the GLP-2 peptide.

    PubMed

    Nakao, Yusuke; Horiguchi, Michiko; Nakamura, Ryuji; Sasaki-Hamada, Sachie; Ozawa, Chihiro; Funane, Taichi; Ozawa, Ryo; Oka, Jun-Ichiro; Yamashita, Chikamasa

    2016-12-30

    Depression is a common mental disorder. More than 350 million people of all ages suffer from depression worldwide. Although a number of antidepressants are available, >20% of patients with major depressive disorder suffer from treatment-resistant depression. Therefore, development of novel therapeutics to overcome this condition is required. We reported that intracerebroventricular administration of glucagon-like peptide-2 (GLP-2) exerts antidepressant-like effects treated with or without adrenocorticotropic hormone. In the present study, we developed a nasal formulation of GLP-2 containing 5% polyoxyethylene (25) lauryl ether and 1% β-cyclodextrin that enhanced the resistance of GLP-2 to inactivation by dipeptidyl peptidase-4. Intranasal administration of this formulation (60μg/kg) increased the delivery of GLP-2 to the brain and had antidepressant-like effects on rats. These results suggest the potential of the GLP-2 nasal formulation for use as a novel antidepressant. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Incretin-related drug therapy in heart failure.

    PubMed

    Vest, Amanda R

    2015-02-01

    The new pharmacological classes of GLP-1 agonists and DPP-4 inhibitors are now widely used in diabetes and have been postulated as beneficial in heart failure. These proposed benefits arise from the inter-related pathophysiologies of diabetes and heart failure (diabetes increases the risk of heart failure, and heart failure can induce insulin resistance) and also in light of the dysfunctional myocardial energetics seen in heart failure. The normal heart utilizes predominantly fatty acids for energy production, but there is some evidence to suggest that increased myocardial glucose uptake may be beneficial for the failing heart. Thus, GLP-1 agonists, which stimulate glucose-dependent insulin release and enhance myocardial glucose uptake, have become a focus of investigation in both animal models and humans with heart failure. Limited pilot data for GLP-1 agonists shows potential improvements in systolic function, hemodynamics, and quality of life, forming the basis for current phase II trials.

  6. Measuring the radium quartet (228Ra, 226Ra, 224Ra, 223Ra) in seawater samples using gamma spectrometry.

    PubMed

    van Beek, P; Souhaut, M; Reyss, J-L

    2010-07-01

    Radium isotopes are widely used in marine studies (eg. to trace water masses, to quantify mixing processes or to study submarine groundwater discharge). While 228Ra and 226Ra are usually measured using gamma spectrometry, short-lived Ra isotopes (224Ra and 223Ra) are usually measured using a Radium Delayed Coincidence Counter (RaDeCC). Here we show that the four radium isotopes can be analyzed using gamma spectrometry. We report 226Ra, 228Ra, 224Ra, 223Ra activities measured using low-background gamma spectrometry in standard samples, in water samples collected in the vicinity of our laboratory (La Palme and Vaccarès lagoons, France) but also in seawater samples collected in the plume of the Amazon river, off French Guyana (AMANDES project). The 223Ra and 224Ra activities determined in these samples using gamma spectrometry were compared to the activities determined using RaDeCC. Activities determined using the two techniques are in good agreement. Uncertainties associated with the 224Ra activities are similar for the two techniques. RaDeCC is more sensitive for the detection of low 223Ra activities. Gamma spectrometry thus constitutes an alternate method for the determination of short-lived Ra isotopes. 2009 Elsevier Ltd. All rights reserved.

  7. Feeding and GLP-1 receptor activation stabilize β-catenin in specific hypothalamic nuclei in male rats.

    PubMed

    McEwen, Hayden J L; Cognard, Emmanuelle; Ladyman, Sharon R; Khant-Aung, Zin; Tups, Alexander; Shepherd, Peter R; Grattan, David R

    2018-05-11

    β-catenin is a multifunctional protein that can act in the canonical Wnt/β-catenin pathway to regulate gene expression but can also bind to cadherin proteins in adherens junctions where it plays a key role in regulating cytoskeleton linked with these junctions. Recently, evidence has been presented indicating an essential role for β-catenin in regulating trafficking of insulin vesicles in β-cells and showing that changes in nutrient levels rapidly alter levels of β-catenin in these cells. Given the importance of neuroendocrine hormone secretion in the regulation of whole body glucose homeostasis, the objective of this study was to investigate whether β-catenin signalling is regulated in the hypothalamus during the normal physiological response to food intake. Rats were subjected to a fasting/re-feeding paradigm, and then samples collected at specific timepoints for analysis of β-catenin expression by immunohistochemistry and Western blotting. Changes in gene expression were assessed by RT-qPCR. Using immunohistochemistry, feeding acutely increased detectable cytoplasmic levels of β-catenin ('stabilized β-catenin') in neurons in specific regions of the hypothalamus involved in metabolic regulation, including the arcuate, dorsomedial and paraventricular nuclei of the hypothalamus. Feeding-induced elevations in β-catenin in these nuclei were associated with increased transcription of several genes that are known to be responsive to Wnt/β-catenin signalling. The effect of feeding was mimicked by administration of the GLP-1 agonist exendin-4, and was characterized by cAMP-dependent phosphorylation of β-catenin at serine residues 552 and 675. The data suggest that β-catenin/TCF signalling is involved in metabolic sensing in the hypothalamus. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  8. Brain reward-system activation in response to anticipation and consumption of palatable food is altered by glucagon-like peptide-1 receptor activation in humans.

    PubMed

    van Bloemendaal, L; Veltman, D J; Ten Kulve, J S; Groot, P F C; Ruhé, H G; Barkhof, F; Sloan, J H; Diamant, M; Ijzerman, R G

    2015-09-01

    To test the hypothesis that food intake reduction after glucagon-like peptide-1 (GLP-1) receptor activation is mediated through brain areas regulating anticipatory and consummatory food reward. As part of a larger study, we determined the effects of GLP-1 receptor activation on brain responses to anticipation and receipt of chocolate milk versus a tasteless solution, using functional MRI (fMRI). Obese subjects with type 2 diabetes, and obese and lean subjects with normoglycaemia (n = 48) underwent three fMRI sessions at separate visits with intravenous infusion of the GLP-1 receptor agonist exenatide, exenatide with prior GLP-1 receptor blockade by exendin-9-39 or placebo, during somatostatin pituitary-pancreatic clamps. Body mass index negatively correlated with brain responses to receipt of chocolate milk and positively correlated with anticipation of receipt of chocolate milk in brain areas regulating reward, appetite and motivation. Exenatide increased brain responses to receipt of chocolate milk and decreased anticipation of receipt of chocolate milk compared with placebo, paralleled by reductions in food intake. Exendin-9-39 largely prevented these effects. Our findings show that GLP-1 receptor activation decreases anticipatory food reward, which may reduce cravings for food and increases consummatory food reward, which may prevent overeating. © 2015 John Wiley & Sons Ltd.

  9. Effect of GLP-1 Receptor Activation on Offspring Kidney Health in a Rat Model of Maternal Obesity.

    PubMed

    Glastras, Sarah J; Chen, Hui; McGrath, Rachel T; Zaky, Amgad A; Gill, Anthony J; Pollock, Carol A; Saad, Sonia

    2016-03-23

    Maternal obesity is associated with an increased risk of chronic disease in offspring, including type 2 diabetes (T2D). Exendin-4 (Exd-4) activates the glucagon like peptide-1 (GLP-1) receptor thereby decreasing serum glucose levels and body weight. In addition, Exd-4 has been shown to reduce renal and cardiac complications in experimental models of T2D. We hypothesized that treatment with Exd-4 would ameliorate the detrimental effects of maternal and diet-induced obesity on renal characteristics in offspring. Female Sprague-Dawley rats were fed either normal or high-fat diet (HFD) for 6 weeks prior to pregnancy, during pregnancy and lactation, and their offspring were weaned to normal or HFD. The offspring were randomized to Exd-4 or placebo from weaning and their kidneys harvested at Week 9. We found that the kidneys of offspring from obese mothers, regardless of postnatal diet, had significantly increased markers of inflammation, oxidative stress and fibrosis. Exd-4 ameliorated the negative renal effects of maternal obesity and in particular, reduced renal inflammation, oxidative stress and fibrosis. In conclusion, maternal obesity has persisting effects on renal structure in the offspring. GLP-1 analogues are potentially useful for protecting against the deleterious effects of maternal obesity on renal physiology in offspring.

  10. Inhibition by TRPA1 agonists of compound action potentials in the frog sciatic nerve

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Matsushita, Akitomo; Ohtsubo, Sena; Fujita, Tsugumi

    Highlights: •TRPA1 agonists inhibited compound action potentials in frog sciatic nerves. •This inhibition was not mediated by TRPA1 channels. •This efficacy was comparable to those of lidocaine and cocaine. •We found for the first time an ability of TRPA1 agonists to inhibit nerve conduction. -- Abstract: Although TRPV1 and TRPM8 agonists (vanilloid capsaicin and menthol, respectively) at high concentrations inhibit action potential conduction, it remains to be unknown whether TRPA1 agonists have a similar action. The present study examined the actions of TRPA1 agonists, cinnamaldehyde (CA) and allyl isothiocyanate (AITC), which differ in chemical structure from each other, on compoundmore » action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method. CA and AITC concentration-dependently reduced the peak amplitude of the CAP with the IC{sub 50} values of 1.2 and 1.5 mM, respectively; these activities were resistant to a non-selective TRP antagonist ruthenium red or a selective TRPA1 antagonist HC-030031. The CA and AITC actions were distinct in property; the latter but not former action was delayed in onset and partially reversible, and CA but not AITC increased thresholds to elicit CAPs. A CAP inhibition was seen by hydroxy-α-sanshool (by 60% at 0.05 mM), which activates both TRPA1 and TRPV1 channels, a non-vanilloid TRPV1 agonist piperine (by 20% at 0.07 mM) and tetrahydrolavandulol (where the six-membered ring of menthol is opened; IC{sub 50} = 0.38 mM). It is suggested that TRPA1 agonists as well as TRPV1 and TRPM8 agonists have an ability to inhibit nerve conduction without TRP activation, although their agonists are quite different in chemical structure from each other.« less

  11. Comparison of postprandial profiles of ghrelin, active GLP-1, and total PYY to meals varying in fat and carbohydrate and their association with hunger and the phases of satiety.

    PubMed

    Gibbons, Catherine; Caudwell, Phillipa; Finlayson, Graham; Webb, Dominic-Luc; Hellström, Per M; Näslund, Erik; Blundell, John E

    2013-05-01

    The relationship between postprandial peptides at circulating physiological levels and short-term appetite control is not well understood. The purpose of this study was first to compare the postprandial profiles of ghrelin, glucagon-like peptide 1 (GLP-1), and peptide YY (PYY) after isoenergetic meals differing in fat and carbohydrate content and second to examine the relationships between ghrelin, GLP-1, and PYY with hunger, fullness, and energy intake. Plasma was collected before and periodically after the meals for 180 minutes, after which time ad libitum food was provided. Simultaneous ratings of hunger and fullness were tracked for 180 minutes through phases identified as early (0-60 minutes) and late (60-180 minutes) satiety. This study was conducted at the Psychobiology and Energy Balance Research Unit, University of Leeds. The participants were 16 healthy overweight/obese adults. Changes in hunger and fullness and metabolic markers were indicators of the impact of the meals on satiety. Ghrelin was influenced similarly by the 2 meals [F(1, 12) = 0.658, P = .433] and was significantly associated with changes in hunger (P < .05), which in turn correlated with food intake (P < .05). GLP-1 and PYY increased more by the high-fat meal [F(1, 15) = 5.099 and F(1, 14) = 5.226, P < .05]. GLP-1 was negatively associated with hunger in the late satiety phase and with energy intake (P < .05), but the PYY profile was not associated with hunger or fullness, nor was PYY associated with food intake. The results demonstrate that under these conditions, these peptides respond differently to ingested nutrients. Ghrelin and GLP-1, but not PYY, were associated with short-term control of appetite over the measurement period.

  12. Classical and atypical agonists activate M1 muscarinic acetylcholine receptors through common mechanisms.

    PubMed

    Randáková, Alena; Dolejší, Eva; Rudajev, Vladimír; Zimčík, Pavel; Doležal, Vladimír; El-Fakahany, Esam E; Jakubík, Jan

    2015-07-01

    We mutated key amino acids of the human variant of the M1 muscarinic receptor that target ligand binding, receptor activation, and receptor-G protein interaction. We compared the effects of these mutations on the action of two atypical M1 functionally preferring agonists (N-desmethylclozapine and xanomeline) and two classical non-selective orthosteric agonists (carbachol and oxotremorine). Mutations of D105 in the orthosteric binding site and mutation of D99 located out of the orthosteric binding site decreased affinity of all tested agonists that was translated as a decrease in potency in accumulation of inositol phosphates and intracellular calcium mobilization. Mutation of D105 decreased the potency of the atypical agonist xanomeline more than that of the classical agonists carbachol and oxotremorine. Mutation of the residues involved in receptor activation (D71) and coupling to G-proteins (R123) completely abolished the functional responses to both classical and atypical agonists. Our data show that both classical and atypical agonists activate hM1 receptors by the same molecular switch that involves D71 in the second transmembrane helix. The principal difference among the studied agonists is rather in the way they interact with D105 in the orthosteric binding site. Furthermore, our data demonstrate a key role of D105 in xanomeline wash-resistant binding and persistent activation of hM1 by wash-resistant xanomeline. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Exenatide Once-Weekly Clinical Development: Safety and Efficacy Across a Range of Background Therapies

    PubMed Central

    Stonehouse, Anthony; Walsh, Brandon

    2011-01-01

    Abstract In patients with type 2 diabetes mellitus (T2DM), the physiologic glucagon-like peptide-1 (GLP-1) response, which is involved in glucose regulation through several mechanisms, is dysfunctional. GLP-1 receptor agonists can fill an unmet therapeutic need in the treatment of T2DM: improving glycemic control without increasing the risk of hypoglycemia (except with concomitant sulfonylureas) and reducing weight in a substantial proportion of patients. GLP-1 receptor agonists have impacted established disease treatment algorithms for T2DM. For example, in 2009 the American Diabetes Association and European Association for the Study of Diabetes revised their consensus treatment algorithm to incorporate GLP-1 receptor agonists. GLP-1 receptor agonists were originally represented by exenatide BID (ExBID), a short-acting agent requiring twice-daily injections at mealtime. The longer-acting agent liraglutide, requiring once-daily injections, recently received regulatory approval. Several other long-acting agents are in clinical development, one of which is the once-weekly formulation of exenatide (exenatide once weekly [ExQW]). This article reviews the clinical development of ExQW in the DURATION program. Patients in theses clinical trials were receiving various background treatments, ranging from lifestyle therapy to combination oral therapy, although the majority (68%) received metformin monotherapy. Specifically, safety, glycemic control, and weight were compared in patients treated with ExQW versus ExBID, sitagliptin, pioglitazone, or insulin glargine. Moreover, measures of β-cell function, cardiovascular risk, inflammation, and hepatic health were investigated. During ExQW clinical development, consistent clinical efficacy (glycosylated hemoglobin, −1.5% to −1.9%; weight, −2 kg to −4 kg) and safety data were observed in patients with T2DM treated with ExQW. PMID:21732798

  14. The Effect of a Subcutaneous Infusion of GLP-1, OXM, and PYY on Energy Intake and Expenditure in Obese Volunteers

    PubMed Central

    Tan, Tricia; Behary, Preeshila; Tharakan, George; Minnion, James; Al-Najim, Werd; Albrechtsen, Nicolai J. Wewer; Holst, Jens J.

    2017-01-01

    Background: Roux-en-Y gastric bypass (RYGB) surgery is currently the most effective treatment of obesity, although limited by availability and operative risk. The gut hormones Glucagon-like peptide-1 (GLP-1), Peptide YY (PYY), and Oxyntomodulin (OXM) are elevated postprandially after RYGB, which has been postulated to contribute to its metabolic benefits. Objective: We hypothesized that infusion of the three gut hormones to achieve levels similar to those encountered postprandially in RYGB patients might be effective in suppressing appetite. The aim of this study was to investigate the effect of a continuous infusion of GLP-1, OXM, and PYY (GOP) on energy intake and expenditure in obese volunteers. Methods: Obese volunteers were randomized to receive an infusion of GOP or placebo in a single-blinded, randomized, placebo-controlled crossover study for 10.5 hours a day. This was delivered subcutaneously using a pump device, allowing volunteers to remain ambulatory. Ad libitum food intake studies were performed during the infusion, and energy expenditure was measured using a ventilated hood calorimeter. Results: Postprandial levels of GLP-1, OXM, and PYY seen post RYGB were successfully matched using 4 pmol/kg/min, 4 pmol/kg/min, and 0.4 pmol/kg/min, respectively. This dose led to a mean reduction of 32% in food intake. No significant effects on resting energy expenditure were observed. Conclusion: This is, to our knowledge, the first time that an acute continuous subcutaneous infusion of GOP, replicating the postprandial levels observed after RYGB, is shown to be safe and effective in reducing food intake. This data suggests that triple hormone therapy might be a useful tool against obesity. PMID:28379519

  15. GLP-I secretion in healthy and diabetic Wistar rats in response to aqueous extract of Momordica charantia.

    PubMed

    Bhat, Gulzar Ahmad; Khan, Haseeb A; Alhomida, Abdullah S; Sharma, Poonam; Singh, Rambir; Paray, Bilal Ahmad

    2018-05-18

    Diabetes mellitus is one of the major global health disorders increasing at an alarming rate in both developed and developing countries. The objective of this study was to assess the effect of aqueous extract of Momordica charantia (AEMC) on fasting blood glucose (FBG), tissue glycogen, glycosylated haemoglobin, plasma concentrations of insulin and GLP-1 hormone (glucagon-like peptide 1) in healthy and diabetic wistar rats. Male Wistar rats (both normal and diabetic) were treated with AEMC by gavaging (300 mg/kg body wt/day for 28 days). AEMC was found to increase tissue glycogen, serum insulin and GLP-1 non-significantly (P > 0.05) in normal, significantly (P < 0.01) in diabetic Wistar rats, whereas decrease in FBG and Glycosylated haemoglobin non-significantly (P > 0.05) in normal, significantly (P < 0.01) in diabetic Wistar rats. The elevation of GLP-1 level in normal and diabetic treated groups may be due to the L-cell regeneration and proliferation by binding with L-cell receptors and makes a conformational change, resulting in the activation of a series of signal transducers. The polar molecules of M. charantia also depolarize the L-cell through elevation of intracellular Ca 2+ concentration and which in turn releases GLP-1. GLP-1 in turn elevates beta-cell proliferation and insulin secretion. The findings tend to provide a possible explanation for the hypoglycemic action of M. charantia fruit extracts as alternative nutritional therapy in the management and treatment of diabetes.

  16. The AhR agonist VAF347 augments retinoic acid-induced differentiation in leukemia cells

    PubMed Central

    Ibabao, Christopher N.; Bunaciu, Rodica P.; Schaefer, Deanna M.W.; Yen, Andrew

    2015-01-01

    In binary cell-fate decisions, driving one lineage and suppressing the other are conjoined. We have previously reported that aryl hydrocarbon receptor (AhR) promotes retinoic acid (RA)-induced granulocytic differentiation of lineage bipotent HL-60 myeloblastic leukemia cells. VAF347, an AhR agonist, impairs the development of CD14+CD11b+ monocytes from granulo-monocytic (GM) stage precursors. We thus hypothesized that VAF347 propels RA-induced granulocytic differentiation and impairs D3-induced monocytic differentiation of HL-60 cells. Our results show that VAF347 enhanced RA-induced cell cycle arrest, CD11b integrin expression and neutrophil respiratory burst. Granulocytic differentiation is known to be driven by MAPK signaling events regulated by Fgr and Lyn Src-family kinases, the CD38 cell membrane receptor, the Vav1 GEF, the c-Cbl adaptor, as well as AhR, all of which are embodied in a putative signalsome. We found that the VAF347 AhR ligand regulates the signalsome. VAF347 augments RA-induced expression of AhR, Lyn, Vav1, and c-Cbl as well as p47phox. Several interactions of partners in the signalsome appear to be enhanced: Fgr interaction with c-Cbl, CD38, and with pS259c-Raf and AhR interaction with c-Cbl and Lyn. Thus, we report that, while VAF347 impedes monocytic differentiation induced by 1,25-dihydroxyvitamin D3, VAF347 promotes RA-induced differentiation. This effect seems to involve but not to be limited to Lyn, Vav1, c-Cbl, AhR, and Fgr. PMID:25941627

  17. The AhR agonist VAF347 augments retinoic acid-induced differentiation in leukemia cells.

    PubMed

    Ibabao, Christopher N; Bunaciu, Rodica P; Schaefer, Deanna M W; Yen, Andrew

    2015-01-01

    In binary cell-fate decisions, driving one lineage and suppressing the other are conjoined. We have previously reported that aryl hydrocarbon receptor (AhR) promotes retinoic acid (RA)-induced granulocytic differentiation of lineage bipotent HL-60 myeloblastic leukemia cells. VAF347, an AhR agonist, impairs the development of CD14(+)CD11b(+) monocytes from granulo-monocytic (GM) stage precursors. We thus hypothesized that VAF347 propels RA-induced granulocytic differentiation and impairs D3-induced monocytic differentiation of HL-60 cells. Our results show that VAF347 enhanced RA-induced cell cycle arrest, CD11b integrin expression and neutrophil respiratory burst. Granulocytic differentiation is known to be driven by MAPK signaling events regulated by Fgr and Lyn Src-family kinases, the CD38 cell membrane receptor, the Vav1 GEF, the c-Cbl adaptor, as well as AhR, all of which are embodied in a putative signalsome. We found that the VAF347 AhR ligand regulates the signalsome. VAF347 augments RA-induced expression of AhR, Lyn, Vav1, and c-Cbl as well as p47(phox). Several interactions of partners in the signalsome appear to be enhanced: Fgr interaction with c-Cbl, CD38, and with pS259c-Raf and AhR interaction with c-Cbl and Lyn. Thus, we report that, while VAF347 impedes monocytic differentiation induced by 1,25-dihydroxyvitamin D3, VAF347 promotes RA-induced differentiation. This effect seems to involve but not to be limited to Lyn, Vav1, c-Cbl, AhR, and Fgr.

  18. Dipeptidyl peptidase-4 inhibitor ameliorates early renal injury through its anti-inflammatory action in a rat model of type 1 diabetes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kodera, Ryo, E-mail: kodera@cc.okayama-u.ac.jp; Shikata, Kenichi; Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558

    Highlights: •DPP-4 inhibitor decreased urinary albumin excretion in a rat of type 1 diabetes. •DPP-4 inhibitor ameliorated histlogical changes of diabetic nephropathy. •DPP-4 inhibitor has reno-protective effects through anti-inflammatory action. •DPP-4 inhibitor is beneficial on diabetic nephropathy besides lowering blood glucose. -- Abstract: Introduction: Dipeptidyl peptidase-4 (DPP-4) inhibitors are incretin-based drugs in patients with type 2 diabetes. In our previous study, we showed that glucagon-like peptide-1 (GLP-1) receptor agonist has reno-protective effects through anti-inflammatory action. The mechanism of action of DPP-4 inhibitor is different from that of GLP-1 receptor agonists. It is not obvious whether DPP-4 inhibitor prevents the exacerbationmore » of diabetic nephropathy through anti-inflammatory effects besides lowering blood glucose or not. The purpose of this study is to clarify the reno-protective effects of DPP-4 inhibitor through anti-inflammatory actions in the early diabetic nephropathy. Materials and methods: Five-week-old male Sprague–Dawley (SD) rats were divided into three groups; non-diabetes, diabetes and diabetes treated with DPP-4 inhibitor (PKF275-055; 3 mg/kg/day). PKF275-055 was administered orally for 8 weeks. Results: PKF275-055 increased the serum active GLP-1 concentration and the production of urinary cyclic AMP. PKF275-055 decreased urinary albumin excretion and ameliorated histological change of diabetic nephropathy. Macrophage infiltration was inhibited, and inflammatory molecules were down-regulated by PKF275-055 in the glomeruli. In addition, nuclear factor-κB (NF-κB) activity was suppressed in the kidney. Conclusions: These results indicate that DPP-4 inhibitor, PKF275-055, have reno-protective effects through anti-inflammatory action in the early stage of diabetic nephropathy. The endogenous biological active GLP-1 might be beneficial on diabetic nephropathy besides lowering blood glucose.« less

  19. Framework for the quality assurance of 'omics technologies considering GLP requirements.

    PubMed

    Kauffmann, Hans-Martin; Kamp, Hennicke; Fuchs, Regine; Chorley, Brian N; Deferme, Lize; Ebbels, Timothy; Hackermüller, Jörg; Perdichizzi, Stefania; Poole, Alan; Sauer, Ursula G; Tollefsen, Knut E; Tralau, Tewes; Yauk, Carole; van Ravenzwaay, Ben

    2017-12-01

    'Omics technologies are gaining importance to support regulatory toxicity studies. Prerequisites for performing 'omics studies considering GLP principles were discussed at the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) Workshop Applying 'omics technologies in Chemical Risk Assessment. A GLP environment comprises a standard operating procedure system, proper pre-planning and documentation, and inspections of independent quality assurance staff. To prevent uncontrolled data changes, the raw data obtained in the respective 'omics data recording systems have to be specifically defined. Further requirements include transparent and reproducible data processing steps, and safe data storage and archiving procedures. The software for data recording and processing should be validated, and data changes should be traceable or disabled. GLP-compliant quality assurance of 'omics technologies appears feasible for many GLP requirements. However, challenges include (i) defining, storing, and archiving the raw data; (ii) transparent descriptions of data processing steps; (iii) software validation; and (iv) ensuring complete reproducibility of final results with respect to raw data. Nevertheless, 'omics studies can be supported by quality measures (e.g., GLP principles) to ensure quality control, reproducibility and traceability of experiments. This enables regulators to use 'omics data in a fit-for-purpose context, which enhances their applicability for risk assessment. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Aqueous fraction of Beta vulgaris ameliorates hyperglycemia in diabetic mice due to enhanced glucose stimulated insulin secretion, mediated by acetylcholine and GLP-1, and elevated glucose uptake via increased membrane bound GLUT4 transporters.

    PubMed

    Ul Kabir, Ashraf; Samad, Mehdi Bin; Ahmed, Arif; Jahan, Mohammad Rajib; Akhter, Farjana; Tasnim, Jinat; Hasan, S M Nageeb; Sayfe, Sania Sarker; Hannan, J M A

    2015-01-01

    The study was designed to investigate the probable mechanisms of anti-hyperglycemic activity of B. Vulgaris. Aqueous fraction of B. Vulgaris extract was the only active fraction (50mg/kg). Plasma insulin level was found to be the highest at 30 mins after B. Vulgaris administration at a dose of 200mg/kg. B. Vulgaris treated mice were also assayed for plasma Acetylcholine, Glucagon Like Peptide-1 (GLP-1), Gastric Inhibitory Peptide (GIP), Vasoactive Intestinal Peptide, Pituitary Adenylate Cyclase-Activating Peptide (PACAP), Insulin Like Growth Factor-1 (IGF-1), Pancreatic Polypeptides (PP), and Somatostatin, along with the corresponding insulin levels. Plasma Acetylcholine and GLP-1 significantly increased in B. Vulgaris treated animals and were further studied. Pharmacological enhancers, inhibitors, and antagonists of Acetylcholine and GLP-1 were also administered to the test animals, and corresponding insulin levels were measured. These studies confirmed the role of acetylcholine and GLP-1 in enhanced insulin secretion (p<0.05). Principal signaling molecules were quantified in isolated mice islets for the respective pathways to elucidate their activities. Elevated concentrations of Acetylcholine and GLP-1 in B. Vulgaris treated mice were found to be sufficient to activate the respective pathways for insulin secretion (p<0.05). The amount of membrane bound GLUT1 and GLUT4 transporters were quantified and the subsequent glucose uptake and glycogen synthesis were assayed. We showed that levels of membrane bound GLUT4 transporters, glucose-6-phosphate in skeletal myocytes, activity of glycogen synthase, and level of glycogen deposited in the skeletal muscles all increased (p<0.05). Findings of the present study clearly prove the role of Acetylcholine and GLP-1 in the Insulin secreting activity of B. Vulgaris. Increased glucose uptake in the skeletal muscles and subsequent glycogen synthesis may also play a part in the anti-hyperglycemic activity of B. Vulgaris.

  1. Aqueous Fraction of Beta vulgaris Ameliorates Hyperglycemia in Diabetic Mice due to Enhanced Glucose Stimulated Insulin Secretion, Mediated by Acetylcholine and GLP-1, and Elevated Glucose Uptake via Increased Membrane Bound GLUT4 Transporters

    PubMed Central

    Kabir, Ashraf Ul; Samad, Mehdi Bin; Ahmed, Arif; Jahan, Mohammad Rajib; Akhter, Farjana; Tasnim, Jinat; Hasan, S. M. Nageeb; Sayfe, Sania Sarker; Hannan, J. M. A.

    2015-01-01

    Background The study was designed to investigate the probable mechanisms of anti-hyperglycemic activity of B. Vulgaris. Methodology/Principal Findings Aqueous fraction of B. Vulgaris extract was the only active fraction (50mg/kg). Plasma insulin level was found to be the highest at 30 mins after B. Vulgaris administration at a dose of 200mg/kg. B. Vulgaris treated mice were also assayed for plasma Acetylcholine, Glucagon Like Peptide-1 (GLP-1), Gastric Inhibitory Peptide (GIP), Vasoactive Intestinal Peptide, Pituitary Adenylate Cyclase-Activating Peptide (PACAP), Insulin Like Growth Factor-1 (IGF-1), Pancreatic Polypeptides (PP), and Somatostatin, along with the corresponding insulin levels. Plasma Acetylcholine and GLP-1 significantly increased in B. Vulgaris treated animals and were further studied. Pharmacological enhancers, inhibitors, and antagonists of Acetylcholine and GLP-1 were also administered to the test animals, and corresponding insulin levels were measured. These studies confirmed the role of acetylcholine and GLP-1 in enhanced insulin secretion (p<0.05). Principal signaling molecules were quantified in isolated mice islets for the respective pathways to elucidate their activities. Elevated concentrations of Acetylcholine and GLP-1 in B. Vulgaris treated mice were found to be sufficient to activate the respective pathways for insulin secretion (p<0.05). The amount of membrane bound GLUT1 and GLUT4 transporters were quantified and the subsequent glucose uptake and glycogen synthesis were assayed. We showed that levels of membrane bound GLUT4 transporters, glucose-6-phosphate in skeletal myocytes, activity of glycogen synthase, and level of glycogen deposited in the skeletal muscles all increased (p<0.05). Conclusion Findings of the present study clearly prove the role of Acetylcholine and GLP-1 in the Insulin secreting activity of B. Vulgaris. Increased glucose uptake in the skeletal muscles and subsequent glycogen synthesis may also play a part in

  2. Immunomodulatory effect of ganoderma lucidum polysaccharides (GLP) on long-term heavy-load exercising mice.

    PubMed

    Shi, Yali; Cai, Dehua; Wang, Xiaojie; Liu, Xinshen

    2012-12-01

    Long-term heavy-load exercise can lead to a decrease in the organism's immune response. In this study, we used 100 Kunming (KM) mice to investigate the immune-regulatory effects of Ganoderma lucidum polysaccharides (GLP) on long-term heavy-load exercising mice. Peripheral white blood cells (WBC), the absolute value of neutrophils (NEUT), the phagocytic function of macrophages, serum agglutination valence, and the number of plaque-forming cells (PFC) were evaluated 4 weeks after gavaging long-term heavy-load exercising mice with GLP. After exercise, the WBC count in peripheral blood, absolute neutrophil count, macrophage phagocytic index, serum agglutination valence, and the number of plaque-forming cells were significantly reduced in the mice not fed GLP. Both medium and high doses of GLP drastically increased peripheral WBC, absolute neutrophil count, macrophage phagocytic index, serum agglutination valence, and the number of plaque-forming cells in long-term heavy-load exercising mice. High doses of GLP increased peritoneal macrophage phagocytic rate considerably. With this study, we demonstrate that 4 weeks of heavy-load exercise can lead to exercise-induced immunosuppression in mice. A supplement of GLP fed to these mice improves both non-specific and specific immune responses among these mice. The effect for the high-dose GLP treatment is especially significant.

  3. Importance of agonists in alpha-adrenoceptor classification and localisation of alpha1-adrenoceptors in human prostate.

    PubMed

    McGrath, J C; Naghadeh, M A; Pediani, J D; Mackenzie, J F; Daly, C J

    1999-01-01

    alpha-Adrenoceptor blocker drugs are commonly used in the clinical (non-surgical) treatment of BPH. alpha1-adrenoceptors were originally sub-divided using agonists but, subsequently, were sub-divided using only antagonists in ligand-ligand interactions, which did not require agonists at all. Ultimately, proof that adrenoceptors are functional receptors for the natural ligands, noradrenaline and adrenaline, requires that agonists be used. The earlier excitement engendered by finding varying agonist potency series in different tissues has not been revisited to place it in the context of current concepts of alpha1-adrenoceptor subtypes. This review will consider the advantages and limitations of different agonists for the study of alpha1-adrenoceptor subtypes including 'extreme' examples where the archetypal alpha1-adrenoceptor agonist phenylephrine activates alpha2-adrenoceptors and others where UK14304, often the alpha2-adrenoceptor agonist of choice, activates alpha1-adrenoceptors. New work will also be presented showing the interaction between agonists and the fluorescent alpha1-adrenoceptor antagonist QAPB. This introduces the novel point of view of studying the displacement of antagonists by agonists. Possible errors in antagonist classification arising from complexity in the actions of agonists and the recently developed method of fluorescent ligand binding on isolated living human prostatic smooth muscle cells will be discussed.

  4. Sphingosine-1-Phosphate Receptor-1 Selective Agonist Enhances Collateral Growth and Protects against Subsequent Stroke

    PubMed Central

    Ichijo, Masahiko; Ishibashi, Satoru; Li, Fuying; Yui, Daishi; Miki, Kazunori; Mizusawa, Hidehiro; Yokota, Takanori

    2015-01-01

    Background and Purpose Collateral growth after acute occlusion of an intracranial artery is triggered by increasing shear stress in preexisting collateral pathways. Recently, sphingosine-1-phosphate receptor-1 (S1PR1) on endothelial cells was reported to be essential in sensing fluid shear stress. Here, we evaluated the expression of S1PR1 in the hypoperfused mouse brain and investigated the effect of a selective S1PR1 agonist on leptomeningeal collateral growth and subsequent ischemic damage after focal ischemia. Methods In C57Bl/6 mice (n = 133) subjected to unilateral common carotid occlusion (CCAO) and sham surgery. The first series examined the time course of collateral growth, cell proliferation, and S1PR1 expression in the leptomeningeal arteries after CCAO. The second series examined the relationship between pharmacological regulation of S1PR1 and collateral growth of leptomeningeal anastomoses. Animals were randomly assigned to one of the following groups: LtCCAO and daily intraperitoneal (ip) injection for 7 days of an S1PR1 selective agonist (SEW2871, 5 mg/kg/day); sham surgery and daily ip injection for 7 days of SEW2871 after surgery; LtCCAO and daily ip injection for 7 days of SEW2871 and an S1PR1 inverse agonist (VPC23019, 0.5 mg/kg); LtCCAO and daily ip injection of DMSO for 7 days after surgery; and sham surgery and daily ip injection of DMSO for 7 days. Leptomeningeal anastomoses were visualized 14 days after LtCCAO by latex perfusion method, and a set of animals underwent subsequent permanent middle cerebral artery occlusion (pMCAO) 7days after the treatment termination. Neurological functions 1hour, 1, 4, and 7days and infarction volume 7days after pMCAO were evaluated. Results In parallel with the increase in S1PR1 mRNA levels, S1PR1 expression colocalized with endothelial cell markers in the leptomeningeal arteries, increased markedly on the side of the CCAO, and peaked 7 days after CCAO. Mitotic cell numbers in the leptomeningeal arteries

  5. Coadministration of VDR and RXR agonists synergistically alleviates atherosclerosis through inhibition of oxidative stress: An in vivo and in vitro study.

    PubMed

    Lin, L M; Peng, F; Liu, Y P; Chai, D J; Ning, R B; Xu, C S; Lin, J X

    2016-08-01

    Diabetes contributes to atherosclerosis partially through induction of oxidative stress. Both vitamin D receptor (VDR) and retinoid X receptor (RXR) agonists exhibit anti-atherogenic effects. We explored the effects of combination treatment with VDR and RXR agonists (represented by calcitriol and bexarotene, respectively) on atherosclerosis progression and the mechanisms involved, using a diabetes model of mice. The animals were intragastrically fed calcitriol (200 ng/kg, twice-a-week), bexarotene (10 mg/kg, once-daily) either alone or in combination for 12 weeks. VDR and RXR agonists delayed atherosclerosis progression independent of serum lipid and glucose levels, and significantly reduced the protein expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit gp91phox and nuclear factor-kappa B (NF-κB) subunit p65, as well as plasma biomarkers of oxidative stress and inflammation. Combination therapy alleviated atherosclerosis and inhibited indexes of oxidative stress and inflammation to a greater extent than either monotherapy. In the in vitro study, naturally occurring VDR ligand 1α,25-dihydroxyvitamin D3 (1,25[OH]2D3) and RXR ligand 9-cis retinoic acid (9-cis-RA), both significantly inhibited high-glucose-induced endothelial cell apoptosis. Co-administration of VDR and RXR ligands produced synergistic protection against endothelial apoptosis by antagonizing the protein kinase C /NADPH oxidase/reactive oxygen species pathway. The inhibitory effects of 9-cis-RA on oxidative stress was attenuated when VDR was downregulated by VDR siRNA; however, downregulation of RXR by RXR siRNA imposed no influence on the effects of 1,25(OH)2D3. Combination treatment with VDR and RXR agonists synergistically alleviated diabetic atherosclerosis through inhibition of oxidative stress, and the preventive effects of RXR agonist may partially depend on VDR activation. Copyright © 2016. Published by Elsevier Ireland Ltd.

  6. Short-term intervention with liraglutide improved eating behavior in obese women with polycystic ovary syndrome.

    PubMed

    Jensterle, Mojca; Kocjan, Tomaz; Kravos, Nika Aleksandra; Pfeifer, Marija; Janez, Andrej

    2015-01-01

    Glucagon-like peptide 1 receptor agonists (GLP-1 RA) stimulate satiety leading to reductions in food intake and body weight. The effects of long- acting GLP-1 RA liraglutide on eating behavior of women with PCOS have not been investigated yet. Thirty-six obese women with PCOS (mean ± SD, aged 31.2 ± 7.8 years, with BMI 38.7 ± 0.1 kg/m(2)), pretreated with metformin (1000 mg BID) were switched to liraglutide 1.2 mg QD sc for 12 weeks. Adiposity parameters and eating behavior as assessed by Three-Factor Eating Questionnaire (TFEQ-R18) were examined at baseline and after 12 weeks. Subjects treated with liraglutide lost on average 3.8 ± 0.1 kg (p < 0.001). Significant reductions of waist circumference and visceral adipose tissue (VAT) mass, volume and area were demonstrated from liraglutide induction to the end of the study. TFEQ-R18 scores were significantly different pre- and post-liraglutide intervention. After treatment with liraglutide the uncontrolled eating (UE) score decreased from 36.8 ± 24.5 to 19.6 ± 18.4 (p < 0.001) and emotional eating (EE) score decreased from 49.9 ± 33.3 to 28.5 ± 26.9 (p < 0.001). Scores for cognitive restraint (CR) were not changed. Short-term liraglutide treatment was associated with weight loss and significantly improved eating behavior in obese women with PCOS.

  7. Effects of oxytocin on serotonin 1B agonist-induced autism-like behavior in mice.

    PubMed

    Lawson, Sarah K; Gray, Andrew C; Woehrle, Nancy S

    2016-11-01

    Social impairments in autism remain poorly understood and without approved pharmacotherapies. Novel animals models are needed to elucidate mechanisms and evaluate novel treatments for the social deficits in autism. Recently, serotonin 1B receptor (5-HT1B) agonist challenge in mice was shown to induce autism-like behaviors including perseveration, reduced prepulse inhibition, and delayed alternation deficits. However, the effects of 5-HT1B agonists on autism-related social behaviors in mice remain unknown. Here, we examine the effects of 5-HT1B agonist challenge on sociability and preference for social novelty in mice. We also examine the effects of 5-HT1B agonist treatment on average rearing duration, a putative rodent measure of non-selective attention. Non-selective attention is an associated feature of autism that is also not well understood. We show that 5-HT1B receptor activation reduces sociability, preference for social novelty, and rearing in mice. In addition, we examine the ability of oxytocin, an off-label treatment for the social impairments in autism, to reverse 5-HT1B agonist-induced social and attention deficits in mice. We show that oxytocin restores social novelty preference in mice treated with a 5-HT1B agonist. We also show that oxytocin attenuates 5-HT1B agonist-induced sociability and rearing deficits in mice. Our results suggest that 5-HT1B agonist challenge provides a useful pharmacological mouse model for aspects of autism, and implicate 5-HT1B in autism social and attention deficits. Moreover, our findings suggest that oxytocin may treat the social deficits in autism through a mechanism involving 5-HT1B. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Radium isotope ((223)Ra, (224)Ra, (226)Ra and (228)Ra) distribution near Brazil's largest port, Paranaguá Bay, Brazil.

    PubMed

    Dias, Thais H; de Oliveira, Joselene; Sanders, Christian J; Carvalho, Franciane; Sanders, Luciana M; Machado, Eunice C; Sá, Fabian

    2016-10-15

    This work investigates the (223)Ra, (224)Ra, (226)Ra and (228)Ra isotope distribution in river, estuarine waters and sediments of the Paranaguá Estuarine Complex (PEC). The stratification of the Ra isotopes along water columns indicate differing natural sources. In sediments, the radium isotope activities was inversely proportional to the particle size. The highest concentrations of (223)Ra, (224)Ra, (226)Ra and (228)Ra in the water column were found in the bottom more saline waters and towards the inner of the estuary. These relatively high concentrations towards the bottom of the estuary may be attributed to the influence of tidally driven groundwater source and desorption from particles at the maximum turbidity zone. The apparent river water ages from the radium isotope ratios, (223)Ra/(224)Ra and (223)Ra/(228)Ra, indicate that the principal rivers that flow into the estuary have residence times from between 6 and 11days. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Carbachol-Induced Reduction in the Activity of Adult Male Zebra Finch RA Projection Neurons

    PubMed Central

    Meng, Wei; Wang, Song-Hua; Li, Dong-Feng

    2016-01-01

    Cholinergic mechanism is involved in motor behavior. In songbirds, the robust nucleus of the arcopallium (RA) is a song premotor nucleus in the pallium and receives cholinergic inputs from the basal forebrain. The activity of projection neurons in RA determines song motor behavior. Although many evidences suggest that cholinergic system is implicated in song production, the cholinergic modulation of RA is not clear until now. In the present study, the electrophysiological effects of carbachol, a nonselective cholinergic receptor agonist, were investigated on the RA projection neurons of adult male zebra finches through whole-cell patch-clamp techniques in vitro. Our results show that carbachol produced a significant decrease in the spontaneous and evoked action potential (AP) firing frequency of RA projection neurons, accompanying a hyperpolarization of the membrane potential, an increase in the evoked AP latency, afterhyperpolarization (AHP) peak amplitude, and AHP time to peak, and a decrease in the membrane input resistance, membrane time constant, and membrane capacitance. These results indicate that carbachol reduces the activity of RA projection neurons by hyperpolarizing the resting membrane potential and increasing the AHP and the membrane conductance, suggesting that the cholinergic modulation of RA may play an important role in song production. PMID:26904300

  10. Carbachol-Induced Reduction in the Activity of Adult Male Zebra Finch RA Projection Neurons.

    PubMed

    Meng, Wei; Wang, Song-Hua; Li, Dong-Feng

    2016-01-01

    Cholinergic mechanism is involved in motor behavior. In songbirds, the robust nucleus of the arcopallium (RA) is a song premotor nucleus in the pallium and receives cholinergic inputs from the basal forebrain. The activity of projection neurons in RA determines song motor behavior. Although many evidences suggest that cholinergic system is implicated in song production, the cholinergic modulation of RA is not clear until now. In the present study, the electrophysiological effects of carbachol, a nonselective cholinergic receptor agonist, were investigated on the RA projection neurons of adult male zebra finches through whole-cell patch-clamp techniques in vitro. Our results show that carbachol produced a significant decrease in the spontaneous and evoked action potential (AP) firing frequency of RA projection neurons, accompanying a hyperpolarization of the membrane potential, an increase in the evoked AP latency, afterhyperpolarization (AHP) peak amplitude, and AHP time to peak, and a decrease in the membrane input resistance, membrane time constant, and membrane capacitance. These results indicate that carbachol reduces the activity of RA projection neurons by hyperpolarizing the resting membrane potential and increasing the AHP and the membrane conductance, suggesting that the cholinergic modulation of RA may play an important role in song production.

  11. Retinoic acid has different effects on UCP1 expression in mouse and human adipocytes

    PubMed Central

    2013-01-01

    Background Increased adipose thermogenesis is being considered as a strategy aimed at preventing or reversing obesity. Thus, regulation of the uncoupling protein 1 (UCP1) gene in human adipocytes is of significant interest. Retinoic acid (RA), the carboxylic acid form of vitamin A, displays agonist activity toward several nuclear hormone receptors, including RA receptors (RARs) and peroxisome proliferator-activated receptor δ (PPARδ). Moreover, RA is a potent positive regulator of UCP1 expression in mouse adipocytes. Results The effects of all-trans RA (ATRA) on UCP1 gene expression in models of mouse and human adipocyte differentiation were investigated. ATRA induced UCP1 expression in all mouse white and brown adipocytes, but inhibited or had no effect on UCP1 expression in human adipocyte cell lines and primary human white adipocytes. Experiments with various RAR agonists and a RAR antagonist in mouse cells demonstrated that the stimulatory effect of ATRA on UCP1 gene expression was indeed mediated by RARs. Consistently, a PPARδ agonist was without effect. Moreover, the ATRA-mediated induction of UCP1 expression in mouse adipocytes was independent of PPARγ coactivator-1α. Conclusions UCP1 expression is differently affected by ATRA in mouse and human adipocytes. ATRA induces UCP1 expression in mouse adipocytes through activation of RARs, whereas expression of UCP1 in human adipocytes is not increased by exposure to ATRA. PMID:24059847

  12. Future issues including broadening the scope of the GLP principles.

    PubMed

    Liem, Francisca E; Lehr, Mark J

    2008-01-01

    When the principles of good laboratory practice (GLP) were drafted in 1982 by the Organisation for Economic Cooperation and Development (OECD) the electronic era was in its infant stages and many of the issues surrounding what may affect the environment and human health was not expected. Today, advances in technology for capturing and recording data for the reconstruction of a study are available and are being developed operating at speeds which could not have been known or understood in years past. Since that time, the United States Environmental Protection Agency (EPA) has required the conduct of additional studies in support of a pesticide registration in accordance with the GLP regulations. However, not all of these studies are required in other countries or may not require adherence to the principles of GLP. Companies are using computer models as virtual studies instead of inlife or bench type regulated research. Studies are often conducted at institutions of higher learning because of the academic expertise they offer. What is the overall impact advancing technology has on the principles of GLP? Are monitoring authorities (MAs) ready? The medical products field faces similar issues. Development and testing of these products and devices is being conducted similar to development and testing in the pesticide arena. To garner trust in mutual acceptance of data, each participating country must adhere to practices that ensure the highest standards of quality and integrity. The GLP inspector will need to have a good understanding of the science supporting the study conduct and the electronic systems that generate process and maintain study records.

  13. Molecular and clinical roles of incretin-based drugs in patients with heart failure.

    PubMed

    Orabi, Bassant; Kaddoura, Rasha; Omar, Amr S; Carr, Cornelia; Alkhulaifi, Abdulaziz

    2018-05-01

    Glucagon-like peptide-1 (GLP-1) agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors produce some beneficial and deleterious effects in diabetic patients not mediated by their glycemic lowering effects, and there is a need for better understanding of the molecular basis of these effects. They possess antioxidant and anti-inflammatory effects with some direct vasodilatory action (animal and human trial data) that may indirectly influence heart failure (HF). Unlike GLP-1R agonists, signaling for HF adverse effects was observed with two DPP-4 inhibitors, saxagliptin and alogliptin. Accordingly, these drugs should be used with caution in heart failure patients.

  14. Measuring 226Ra/228Ra in Oceanic Lavas by MC-ICPMS

    NASA Astrophysics Data System (ADS)

    Standish, J. J.; Sims, K.; Ball, L.; Blusztajn, J.

    2007-12-01

    238U-230Th-226Ra disequilibrium in volcanic rocks provides an important and unique tool to evaluate timescales of recent magmatic processes. Determination of 230Th-226Ra disequilibria requires measurement of U and Th isotopes and concentrations as well as measurement of 226Ra. While measurement of U and Th by ICPMS is now well established, few published studies documenting 226Ra measurement via ICPMS exist. Using 228Ra as an isotope spike we have investigated two ion-counting methods; a 'peak-hopping' routine, where 226Ra and 228Ra are measured in sequence on the central discrete dynode ETP secondary electron multiplier (SEM), and simultaneous measurement of 226Ra and 228Ra on two multiple ion-counter system (MICS) channeltron type detectors mounted on the low end of the collector block. Here we present 226Ra measurement by isotope dilution using the Thermo Fisher NEPTUNE MC-ICPMS. Analysis of external rock standards TML and AThO along with mid-ocean ridge basalt (MORB) and ocean island basalt (OIB) samples show three issues that need to be considered when making precise and accurate Ra measurements: 1) mass bias, 2) background, and 3) relative efficiencies of the detectors when measuring in MICS mode. Due to the absence of an established 226Ra/228Ra standard, we have used U reference material NBL-112A to monitor mass bias. Although Ball et. al., (in press) have shown that U does not serve as an adequate proxy for Th (and thus not likely for Ra either), measurements of rock standards TML and AThO are repeatedly in equilibrium within the uncertainty of the measurements (where total uncertainty includes propagation of the uncertainty in the 226Ra standard used for calibrating the 228Ra spike). For this application, U is an adequate proxy for Ra mass bias at the 1% uncertainly level. The more important issue is the background correction. Because of the extensive chemistry required to separate and purify Ra (typically fg/g level in volcanic rocks), we observe large

  15. Beta-2 receptor agonist exposure in the uterus associated with subsequent risk of childhood asthma.

    PubMed

    Ogawa, Kohei; Tanaka, Satomi; Limin, Yang; Arata, Naoko; Sago, Haruhiko; Yamamoto-Hanada, Kiwako; Narita, Masami; Ohya, Yukihiro

    2017-12-01

    Although the beta-2 receptor agonist (B2RA) is occasionally prescribed in the prenatal period for women with preterm labor, few studies have referred to the long-term effects of intrauterine exposure to B2RA on fetus. We examined the association between intrauterine exposure to B2RA and asthma in the offspring. We obtained data from a hospital-based birth cohort study conducted in Tokyo, Japan. The outcomes of interest were three indicators, consisting of current wheeze, current asthma, and ever asthma at 5 years of age, based on the International Study of Asthma and Allergies in Childhood questionnaire. Logistic regression analysis was used to evaluate the association between intrauterine B2RA exposure and outcomes. To evaluate dose-dependent risk, we categorized children into three groups according to both the cumulative dose and duration (days) and conducted trend analysis. Of 1158 children, 94 (8.1%) were exposed to B2RA in utero, and 191 (16.5%), 111 (9.6%), and 168 (14.5%) children experienced current wheeze, current asthma, and ever asthma, respectively. After adjusting for confounders, we found an increased risk of current asthma caused by B2RA exposure with an adjusted odds ratio of 2.04 (95% confidence interval: 1.02-4.05). Trend analysis showed that B2RA exposure in utero was associated with a dose-dependent increased risk of current asthma in terms of both cumulative dose and duration (P values for trend were .015 and .017, respectively). These results were similar to those for other outcome measures. Exposure to B2RA in utero could be a risk for childhood asthma. © 2017 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.

  16. Cardiovascular risk factor management in patients with RA compared to matched non-RA patients

    PubMed Central

    Cawston, Helene; Bourhis, Francois; Al, Maiwenn; Rutten-van Mölken, Maureen P. M. H.; Liao, Katherine P.; Solomon, Daniel H.

    2016-01-01

    Objective. RA is associated with a 50–60% increase in risk of cardiovascular (CV) death. This study aimed to compare management of CV risk factors in RA and matched non-RA patients. Methods. A retrospective cohort study was conducted using UK clinical practice data. Patients presenting with an incident RA diagnosis were matched 1:4 to non-RA patients based on a propensity score for RA, entry year, CV risk category and treatment received at index date (date of RA diagnosis). Patients tested and treated for CV risk factors as well as those attaining CV risk factor management goals were evaluated in both groups. Results. Between 1987 and 2010, 24 859 RA patients were identified and matched to 87 304 non-RA patients. At index date, groups had similar baseline characteristics. Annual blood pressure, lipids and diabetes-related testing were similar in both groups, although CRP and ESR were higher in RA patients at diagnosis and decreased over time. RA patients prescribed antihypertensives increased from 38.2% at diagnosis to 45.7% at 5 years, from 14.0 to 20.6% for lipid-lowering treatments and from 5.1 to 6.4% for antidiabetics. Similar treatment percentages were observed in non-RA patients, although slightly lower for antihypertensives. Modest (2%) but significantly lower attainment of lipid and diabetes goals at 1 year was observed in RA patients. Conclusion. There were no differences between groups in the frequency of testing and treatment of CV risk factors. Higher CV risk in RA patients seems unlikely to be driven by differences in traditional CV risk factor management. PMID:26705329

  17. Cardiovascular risk factor management in patients with RA compared to matched non-RA patients.

    PubMed

    Alemao, Evo; Cawston, Helene; Bourhis, Francois; Al, Maiwenn; Rutten-van Mölken, Maureen P M H; Liao, Katherine P; Solomon, Daniel H

    2016-05-01

    RA is associated with a 50-60% increase in risk of cardiovascular (CV) death. This study aimed to compare management of CV risk factors in RA and matched non-RA patients. A retrospective cohort study was conducted using UK clinical practice data. Patients presenting with an incident RA diagnosis were matched 1:4 to non-RA patients based on a propensity score for RA, entry year, CV risk category and treatment received at index date (date of RA diagnosis). Patients tested and treated for CV risk factors as well as those attaining CV risk factor management goals were evaluated in both groups. Between 1987 and 2010, 24 859 RA patients were identified and matched to 87 304 non-RA patients. At index date, groups had similar baseline characteristics. Annual blood pressure, lipids and diabetes-related testing were similar in both groups, although CRP and ESR were higher in RA patients at diagnosis and decreased over time. RA patients prescribed antihypertensives increased from 38.2% at diagnosis to 45.7% at 5 years, from 14.0 to 20.6% for lipid-lowering treatments and from 5.1 to 6.4% for antidiabetics. Similar treatment percentages were observed in non-RA patients, although slightly lower for antihypertensives. Modest (2%) but significantly lower attainment of lipid and diabetes goals at 1 year was observed in RA patients. There were no differences between groups in the frequency of testing and treatment of CV risk factors. Higher CV risk in RA patients seems unlikely to be driven by differences in traditional CV risk factor management. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Rheumatology.

  18. A Potent and Site-Selective Agonist of TRPA1.

    PubMed

    Takaya, Junichiro; Mio, Kazuhiro; Shiraishi, Takuya; Kurokawa, Tatsuki; Otsuka, Shinya; Mori, Yasuo; Uesugi, Motonari

    2015-12-23

    TRPA1 is a member of the transient receptor potential (TRP) cation channel family that is expressed primarily on sensory neurons. This chemosensor is activated through covalent modification of multiple cysteine residues with a wide range of reactive compounds including allyl isothiocyanate (AITC), a spicy component of wasabi. The present study reports on potent and selective agonists of TRPA1, discovered through screening 1657 electrophilic molecules. In an effort to validate the mode of action of hit molecules, we noted a new TRPA1-selective agonist, JT010 (molecule 1), which opens the TRPA1 channel by covalently and site-selectively binding to Cys621 (EC50 = 0.65 nM). The results suggest that a single modification of Cys621 is sufficient to open the TRPA1 channel. The TRPA1-selective probe described herein might be useful for further mechanistic studies of TRPA1 activation.

  19. Cost-Effectiveness of IDegLira Versus Insulin Intensification Regimens for the Treatment of Adults with Type 2 Diabetes in the Czech Republic.

    PubMed

    Kvapil, Milan; Prázný, Martin; Holik, Pavel; Rychna, Karel; Hunt, Barnaby

    2017-12-01

    The aim of this study was to evaluate the long-term cost-effectiveness of the insulin degludec/liraglutide combination (IDegLira) versus basal insulin intensification strategies for patients with type 2 diabetes mellitus (T2DM) not optimally controlled on basal insulin in the Czech Republic. Cost-effectiveness was evaluated using the QuintilesIMS Health CORE Diabetes model, an interactive internet-based model that simulates clinical outcomes and costs for cohorts of patients with diabetes. The analysis was conducted from the perspective of the Czech Republic public payer. Sensitivity analyses were conducted to explore the sensitivity of the model to plausible variations in key parameters. The use of IDegLira was associated with an improvement in the quality-adjusted life expectancy of 0.31 quality-adjusted life-years (QALYs), at an additional cost of Czech Koruna (CZK) 107,829 over a patient's lifetime compared with basal-bolus therapy, generating an incremental cost-effectiveness ratio (ICER) of CZK 345,052 per QALY gained. In a scenario analysis, IDegLira was associated with an ICER of CZK 693,763 per QALY gained compared to basal insulin + glucagon-like peptide-1 receptor agonist (GLP-1 RA). The ICERs are below the generally accepted willingness-to-pay threshold (CZK 1,100,000/QALY gained at the time of this analysis). Results from this evaluation suggest that IDegLira is a cost-effective treatment option compared with basal-bolus therapy and basal insulin + GLP-1 RA for patients with T2DM in the Czech Republic whose diabetes is not optimally controlled with basal insulin. Novo Nordisk.

  20. Early induction of IL-1 receptor antagonist (IL-1Ra) in infants and children undergoing surgery.

    PubMed Central

    O Nualláin, E M; Puri, P; Reen, D J

    1993-01-01

    The cytokine response to injury or trauma is of interest in terms of both its mediation of the acute phase response and its possible relation to the immunological depression observed after major surgery. In this study, the production of cytokines IL-1 beta, tumour necrosis factor-alpha (TNF-alpha), IL-6 and the naturally occurring inhibitor of IL-1, IL-1Ra, have been investigated in infants and children undergoing Swenson's pull-through operation for Hirschsprung's disease. Samples of peripheral blood were taken before, during and after surgery for the measurement of cytokines. IL-1Ra levels increased significantly (P < 0.01) at 2 h after commencement of surgery, with maximal levels for individual patients being attained between 3 h and 5 h (range 7.6-67.9 ng/ml). The mean level of IL-1Ra was maximal (26.2 ng/ml) at 5 h and returned to baseline levels between 24 h and 72 h. There were no changes observed in the circulating levels of IL-1 beta in nine out of 11 patients following commencement of surgery. TNF-alpha levels did not increase in any of the patients studied. IL-6 levels increased significantly (P < 0.02) 3 h after commencement of surgery, reaching maximum concentrations at 24 h (range 20-670 pg/ml), with levels falling between 48 h and 72 h. This study demonstrates, in vivo, the independent induction of IL-1Ra without a concomitant increase of IL-1 beta levels after major surgery. It also shows that IL-1Ra is the earliest cytokine produced in response to surgical stress. PMID:8348747

  1. New potential adjuncts to treatment of children with type 1 diabetes mellitus.

    PubMed

    Raman, Vandana S; Heptulla, Rubina A

    2009-04-01

    Insulin administration is the primary therapy for type 1 diabetes mellitus (T1DM). Current available insulin therapies do not successfully enable children with T1DM to reach glycemic goals without side effects such as hypoglycemia and weight gain. Pramlintide is a synthetic analog of human amylin that acts in conjunction with insulin to delay gastric emptying and inhibit the release of glucagon and is indicated for use in patients with type 1 and type 2 diabetes. Recent studies in adult patients have examined the role of glucagon-like peptide 1 (GLP-1) and agents that bind to its receptor in type 1 diabetes. It is hypothesized that a major component of the glycemic effect is attributable to the known action of GLP-1 to delay gastric emptying and to inhibit glucagon secretion. Further studies with the use of amylin analogs and long-acting GLP-1 agonists as congeners with insulin in T1DM are indicated in children. In recent years, our better understanding of the pathophysiology of diabetes has led to the development of new therapies for diabetes. This article reviews the potential use of these newer pharmacologic agents as adjunctive therapy in T1DM in children and adolescents.

  2. Eukaryotic major facilitator superfamily transporter modeling based on the prokaryotic GlpT crystal structure.

    PubMed

    Lemieux, M Joanne

    2007-01-01

    The major facilitator superfamily (MFS) of transporters represents the largest family of secondary active transporters and has a diverse range of substrates. With structural information for four MFS transporters, we can see a strong structural commonality suggesting, as predicted, a common architecture for MFS transporters. The rate for crystal structure determination of MFS transporters is slow, making modeling of both prokaryotic and eukaryotic transporters more enticing. In this review, models of eukaryotic transporters Glut1, G6PT, OCT1, OCT2 and Pho84, based on the crystal structures of the prokaryotic GlpT, based on the crystal structure of LacY are discussed. The techniques used to generate the different models are compared. In addition, the validity of these models and the strategy of using prokaryotic crystal structures to model eukaryotic proteins are discussed. For comparison, E. coli GlpT was modeled based on the E. coli LacY structure and compared to the crystal structure of GlpT demonstrating that experimental evidence is essential for accurate modeling of membrane proteins.

  3. Control of cognition and adaptive behavior by the GLP/G9a epigenetic suppressor complex

    PubMed Central

    Schaefer, Anne; Sampath, Srihari C.; Intrator, Adam; Min, Alice; Gertler, Tracy S.; Surmeier, D. James; Tarakhovsky, Alexander; Greengard, Paul

    2009-01-01

    SUMMARY The genetic basis of cognition and behavioral adaptation to the environment remains poorly understood. Here we demonstrate that the histone methyltransferase complex GLP/G9a controls cognition and adaptive responses in a region-specific fashion in the adult brain. Using conditional mutagenesis in mice, we show that postnatal, neuron-specific deficiency of GLP/G9a leads to de-repression of numerous non-neuronal and neuron progenitor genes in adult neurons. This transcriptional alteration is associated with complex behavioral abnormalities, including defects in learning, motivation and environmental adaptation. The behavioral changes triggered by GLP/G9a deficiency are similar to key symptoms of the human 9q34 mental retardation syndrome that is associated with structural alterations of the GLP gene. The likely causal role of GLP/G9a in mental retardation in mice and humans suggests a key role for the GLP/G9a controlled histone H3K9 di-methylation in regulation of brain function through maintenance of the transcriptional homeostasis in adult neurons. PMID:20005824

  4. Dipeptidyl peptidase IV inhibition potentiates amino acid- and bile acid-induced bicarbonate secretion in rat duodenum.

    PubMed

    Inoue, Takuya; Wang, Joon-Ho; Higashiyama, Masaaki; Rudenkyy, Sergiy; Higuchi, Kazuhide; Guth, Paul H; Engel, Eli; Kaunitz, Jonathan D; Akiba, Yasutada

    2012-10-01

    Intestinal endocrine cells release gut hormones, including glucagon-like peptides (GLPs), in response to luminal nutrients. Luminal L-glutamate (L-Glu) and 5'-inosine monophosphate (IMP) synergistically increases duodenal HCO3- secretion via GLP-2 release. Since L cells express the bile acid receptor TGR5 and dipeptidyl peptidase (DPP) IV rapidly degrades GLPs, we hypothesized that luminal amino acids or bile acids stimulate duodenal HCO3- secretion via GLP-2 release, which is enhanced by DPPIV inhibition. We measured HCO3- secretion with pH and CO2 electrodes using a perfused rat duodenal loop under isoflurane anesthesia. L-Glu (10 mM) and IMP (0.1 mM) were luminally coperfused with or without luminal perfusion (0.1 mM) or intravenous (iv) injection (3 μmol/kg) of the DPPIV inhibitor NVP728. The loop was also perfused with a selective TGR5 agonist betulinic acid (BTA, 10 μM) or the non-bile acid type TGR5 agonist 3-(2-chlorophenyl)-N-(4-chlorophenyl)-N,5-dimethylisoxazole-4-carboxamide (CCDC; 10 μM). DPPIV activity visualized by use of the fluorogenic substrate was present on the duodenal brush border and submucosal layer, both abolished by the incubation with NVP728 (0.1 mM). An iv injection of NVP728 enhanced L-Glu/IMP-induced HCO3- secretion, whereas luminal perfusion of NVP728 had no effect. BTA or CCDC had little effect on HCO3- secretion, whereas NVP728 iv markedly enhanced BTA- or CCDC-induced HCO3- secretion, the effects inhibited by a GLP-2 receptor antagonist. Coperfusion of the TGR5 agonist enhanced L-Glu/IMP-induced HCO3- secretion with the enhanced GLP-2 release, suggesting that TGR5 activation amplifies nutrient sensing signals. DPPIV inhibition potentiated luminal L-Glu/IMP-induced and TGR5 agonist-induced HCO3- secretion via a GLP-2 pathway, suggesting that the modulation of the local concentration of the endogenous secretagogue GLP-2 by luminal compounds and DPPIV inhibition helps regulate protective duodenal HCO3- secretion.

  5. GLP-2: A POORLY UNDERSTOOD MEDIATOR ENROLLED IN VARIOUS BARIATRIC/METABOLIC SURGERY-RELATED PATHOPHYSIOLOGIC MECHANISMS.

    PubMed

    Cazzo, Everton; Gestic, Martinho Antonio; Utrini, Murillo Pimentel; Chaim, Felipe David Mendonça; Geloneze, Bruno; Pareja, José Carlos; Chaim, Elinton Adami; Magro, Daniéla Oliveira

    2016-01-01

    Glucagon-like peptide-2 (GLP-2) is a gastrointestinal hormone whose effects are predominantly trophic on the intestinal mucosa. Critically evaluate the current literature on the influence of bariatric/metabolic surgery on the levels of GLP-2 and its potential clinical implications. s: Narrative review through online research on the databases Medline and Lilacs. There were six prospective human studies, two cross-sectional human studies, and three experimental animal studies selected. There is evidence demonstrating significant increase in the levels of GLP-2 following gastric bypass, Scopinaro operation, and sleeve gastrectomy. There are no differences between gastric bypass and sleeve gastrectomy in regards to the increase in the GLP-2 levels. There is no correlation between the postoperative levels of GLP-2 and the occurrence of adequate or insufficient postoperative weight loss. GLP-2 plays significant roles on the regulation of nutrient absorption, permeability of gut mucosa, control of bone resorption, and regulation of satiety. The overall impact of these effects potentially exerts a significant adaptive or compensatory effect within the context of varied bariatric surgical techniques. O peptídeo semelhante ao glucagon-2 (GLP-2) é hormônio gastrointestinal com efeitos predominantemente tróficos sobre a mucosa intestinal. Avaliar criticamente a literatura atual a respeito da cirurgia bariátrica/metabólica sobre os níveis de GLP-2 e suas potenciais implicações clínicas. Revisão narrativa realizada através de pesquisa on-line nas bases de dados Medline e LILACS. Foram selecionados seis estudos prospectivos em humanos, dois transversais em humanos e três experimentais em animais. Existem evidências demonstrando aumento significativo nos níveis de GLP-2 após o bypass gástrico, a operação de Scopinaro e a gastrectomia vertical. Não foram observadas diferenças entre o bypass gástrico e a gastrectomia vertical em relação ao aumento do GLP-2

  6. Combination of Peptide YY3–36 with GLP-17–36 amide Causes an Increase in First-Phase Insulin Secretion after IV Glucose

    PubMed Central

    Tan, Tricia M.; Salem, Victoria; Troke, Rachel C.; Alsafi, Ali; Field, Benjamin C. T.; De Silva, Akila; Misra, Shivani; Baynes, Kevin C. R.; Donaldson, Mandy; Minnion, James; Ghatei, Mohammad A.; Godsland, Ian F.

    2014-01-01

    Context: The combination of peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) has been proposed as a potential treatment for diabetes and obesity. However, the combined effects of these hormones, PYY3–36 and GLP-17–36 amide, on glucose homeostasis are unknown. Objective: This study sought to investigate the acute effects of PYY3–36 and GLP-17–36 amide, individually and in combination, on insulin secretion and sensitivity. Setting and Design: Using a frequently sampled iv glucose tolerance test (FSIVGTT) and minimal modeling, this study measured the effects of PYY3–36 alone, GLP-17–36 amide alone, and a combination of PYY3–36 and GLP-17–36 amide on acute insulin response to glucose (AIRg) and insulin sensitivity index (SI) in 14 overweight human volunteers, studied in a clinical research facility. Results: PYY3–36 alone caused a small but nonsignificant increase in AIRg. GLP-17–36 amide alone and the combination of PYY3–36 and GLP-17–36 amide did increase AIRg significantly. No significant differences in SI were observed with any intervention. Conclusions: PYY3–36 lacks any significant acute effects on first-phase insulin secretion or SI when tested using an FSIVGTT. Both GLP-17–36 amide alone and the combination of PYY3–36 and GLP-17–36 amide increase first-phase insulin secretion. There does not seem to be any additive or synergistic effect between PYY3–36 and GLP-17–36 amide on first-phase insulin secretion. Neither hormone alone nor the combination had any significant effects on SI. PMID:25144632

  7. GLP1 and glucagon co-secreting pancreatic neuroendocrine tumor presenting as hypoglycemia after gastric bypass

    PubMed Central

    Guimarães, Marta; Rodrigues, Pedro; Pereira, Sofia S; Nora, Mário; Gonçalves, Gil; Albrechtsen, Nicolai Wewer; Hartmann, Bolette; Holst, Jens Juul

    2015-01-01

    Summary Post-prandial hypoglycemia is frequently found after bariatric surgery. Although rare, pancreatic neuroendocrine tumors (pNET), which occasionally are mixed hormone secreting, can lead to atypical clinical manifestations, including reactive hypoglycemia. Two years after gastric bypass surgery for the treatment of severe obesity, a 54-year-old female with previous type 2 diabetes, developed post-prandial sweating, fainting and hypoglycemic episodes, which eventually led to the finding by ultrasound of a 1.8-cm solid mass in the pancreatic head. The 72-h fast test and the plasma chromogranin A levels were normal but octreotide scintigraphy showed a single focus of abnormal radiotracer uptake at the site of the nodule. There were no other clinical signs of hormone secreting pNET and gastrointestinal hormone measurements were not performed. The patient underwent surgical enucleation with complete remission of the hypoglycemic episodes. Histopathology revealed a well-differentiated neuroendocrine carcinoma with low-grade malignancy with positive chromogranin A and glucagon immunostaining. An extract of the resected tumor contained a high concentration of glucagon (26.707 pmol/g tissue), in addition to traces of GLP1 (471 pmol/g), insulin (139 pmol/g) and somatostatin (23 pmol/g). This is the first report of a GLP1 and glucagon co-secreting pNET presenting as hypoglycemia after gastric bypass surgery. Although pNET are rare, they should be considered in the differential diagnosis of the clinical approach to the post-bariatric surgery hypoglycemia patient. Learning points pNETs can be multihormonal-secreting, leading to atypical clinical manifestations.Reactive hypoglycemic episodes are frequent after gastric bypass.pNETs should be considered in the differential diagnosis of hypoglycemia after bariatric surgery. PMID:26266036

  8. Reconstitution and functional comparison of purified GlpF and AqpZ, the glycerol and water channels from Escherichia coli.

    PubMed

    Borgnia, M J; Agre, P

    2001-02-27

    A large family of membrane channel proteins selective for transport of water (aquaporins) or water plus glycerol (aquaglyceroporins) has been found in diverse life forms. Escherichia coli has two members of this family-a water channel, AqpZ, and a glycerol facilitator, GlpF. Despite having similar primary amino acid sequences and predicted structures, the oligomeric state and solute selectivity of AqpZ and GlpF are disputed. Here we report biochemical and functional characterizations of affinity-purified GlpF and compare it to AqpZ. Histidine-tagged (His-GlpF) and hemagglutinin-tagged (HA-GlpF) polypeptides encoded by a bicistronic construct were expressed in bacteria. HA-GlpF and His-GlpF appear to form oligomers during Ni-nitrilotriacetate affinity purification. Sucrose gradient sedimentation analyses showed that the oligomeric state of octyl glucoside-solubilized GlpF varies: low ionic strength favors subunit dissociation, whereas Mg(2+) stabilizes tetrameric assembly. Reconstitution of affinity-purified GlpF into proteoliposomes increases glycerol permeability more than 100-fold and water permeability up to 10-fold compared with control liposomes. Glycerol and water permeability of GlpF both occur with low Arrhenius activation energies and are reversibly inhibited by HgCl(2). Our studies demonstrate that, unlike AqpZ, a water-selective stable tetramer, purified GlpF exists in multiple oligomeric forms under nondenaturing conditions and is highly permeable to glycerol but less well permeated by water.

  9. Molecular modelling studies on the ORL1-receptor and ORL1-agonists

    NASA Astrophysics Data System (ADS)

    Bröer, Britta M.; Gurrath, Marion; Höltje, Hans-Dieter

    2003-11-01

    The ORL1 ( opioid receptor like 1)- receptor is a member of the family of rhodopsin-like G protein-coupled receptors (GPCR) and represents an interesting new therapeutical target since it is involved in a variety of biomedical important processes, such as anxiety, nociception, feeding, and memory. In order to shed light on the molecular basis of the interactions of the GPCR with its ligands, the receptor protein and a dataset of specific agonists were examined using molecular modelling methods. For that purpose, the conformational space of a very potent non-peptide ORL1-receptor agonist (Ro 64-6198) with a small number of rotatable bonds was analysed in order to derive a pharmacophoric arrangement. The conformational analyses yielded a conformation that served as template for the superposition of a set of related analogues. Structural superposition was achieved by employing the program FlexS. Using the experimental binding data and the superposition of the ligands, a 3D-QSAR analysis applying the GRID/GOLPE method was carried out. After the ligand-based modelling approach, a 3D model of the ORL1-receptor has been constructed using homology modelling methods based on the crystal structure of bovine rhodopsin. A representative structure of the model taken from molecular dynamics simulations was used for a manual docking procedure. Asp-130 and Thr-305 within the ORL1-receptor model served as important hydrophilic interaction partners. Furthermore, a hydrophobic cavity was identified stabilizing the agonists within their binding site. The manual docking results were supported using FlexX, which identified the same protein-ligand interaction points.

  10. Efficacy and safety of canagliflozin when used in conjunction with incretin-mimetic therapy in patients with type 2 diabetes.

    PubMed

    Fulcher, G; Matthews, D R; Perkovic, V; de Zeeuw, D; Mahaffey, K W; Mathieu, C; Woo, V; Wysham, C; Capuano, G; Desai, M; Shaw, W; Vercruysse, F; Meininger, G; Neal, B

    2016-01-01

    To assess the efficacy and safety of canagliflozin, a sodium glucose co-transporter 2 (SGLT2) inhibitor, in patients with type 2 diabetes enrolled in the CANagliflozin cardioVascular Assessment Study (CANVAS) who were on an incretin mimetic [dipeptidyl peptidase-4 (DPP-4) inhibitor or glucagon-like peptide-1 (GLP-1) receptor agonist]. CANVAS is a double-blind, placebo-controlled study that randomized participants to canagliflozin 100 or 300 mg or placebo added to routine therapy. The present post hoc analysis assessed the efficacy and safety of canagliflozin 100 and 300 mg compared with placebo in subsets of patients from CANVAS who were taking background DPP-4 inhibitors or GLP-1 receptor agonists with or without other antihyperglycaemic agents at week 18. Of the 4330 patients in CANVAS, 316 were taking DPP-4 inhibitors and 95 were taking GLP-1 receptor agonists. At 18 weeks, canagliflozin 100 and 300 mg provided larger placebo-subtracted reductions in glycated haemoglobin (HbA1c) in patients taking DPP-4 inhibitors [-0.56% (95% confidence interval [CI]: -0.77, -0.35), and -0.75% (95% CI: -0.95, -0.54), respectively] and GLP-1 receptor agonists [-1.00% (95% CI: -1.35, -0.65), and -1.06% (95% CI: -1.43, -0.69), respectively]. Body weight and blood pressure (BP) reductions were seen with canagliflozin versus placebo in both subsets. Higher incidences of genital mycotic infections and osmotic diuresis-related adverse events (AEs) were seen with canagliflozin compared with placebo. The incidence of hypoglycaemia was numerically higher with canagliflozin versus placebo; nearly all events occurred in patients on background insulin or insulin secretagogues. In patients on background incretin mimetics, canagliflozin improved HbA1c, body weight and BP, with an increased incidence of AEs related to SGLT2 inhibition. © 2015 John Wiley & Sons Ltd.

  11. Purification of family B G protein-coupled receptors using nanodiscs: Application to human glucagon-like peptide-1 receptor.

    PubMed

    Cai, Yingying; Liu, Yuting; Culhane, Kelly J; DeVree, Brian T; Yang, Yang; Sunahara, Roger K; Yan, Elsa C Y

    2017-01-01

    Family B G protein-coupled receptors (GPCRs) play vital roles in hormone-regulated homeostasis. They are drug targets for metabolic diseases, including type 2 diabetes and osteoporosis. Despite their importance, the signaling mechanisms for family B GPCRs at the molecular level remain largely unexplored due to the challenges in purification of functional receptors in sufficient amount for biophysical characterization. Here, we purified the family B GPCR human glucagon-like peptide-1 (GLP-1) receptor (GLP1R), whose agonists, e.g. exendin-4, are used for the treatment of type 2 diabetes mellitus. The receptor was expressed in HEK293S GnTl- cells using our recently developed protocol. The protocol incorporates the receptor into the native-like lipid environment of reconstituted high density lipoprotein (rHDL) particles, also known as nanodiscs, immediately after the membrane solubilization step followed by chromatographic purification, minimizing detergent contact with the target receptor to reduce denaturation and prolonging stabilization of receptor in lipid bilayers without extra steps of reconstitution. This method yielded purified GLP1R in nanodiscs that could bind to GLP-1 and exendin-4 and activate Gs protein. This nanodisc purification method can potentially be a general strategy to routinely obtain purified family B GPCRs in the 10s of microgram amounts useful for spectroscopic analysis of receptor functions and activation mechanisms.

  12. Purification of family B G protein-coupled receptors using nanodiscs: Application to human glucagon-like peptide-1 receptor

    PubMed Central

    Cai, Yingying; Liu, Yuting; Culhane, Kelly J.; DeVree, Brian T.; Yang, Yang; Sunahara, Roger K.; Yan, Elsa C. Y.

    2017-01-01

    Family B G protein-coupled receptors (GPCRs) play vital roles in hormone-regulated homeostasis. They are drug targets for metabolic diseases, including type 2 diabetes and osteoporosis. Despite their importance, the signaling mechanisms for family B GPCRs at the molecular level remain largely unexplored due to the challenges in purification of functional receptors in sufficient amount for biophysical characterization. Here, we purified the family B GPCR human glucagon-like peptide-1 (GLP-1) receptor (GLP1R), whose agonists, e.g. exendin-4, are used for the treatment of type 2 diabetes mellitus. The receptor was expressed in HEK293S GnTl- cells using our recently developed protocol. The protocol incorporates the receptor into the native-like lipid environment of reconstituted high density lipoprotein (rHDL) particles, also known as nanodiscs, immediately after the membrane solubilization step followed by chromatographic purification, minimizing detergent contact with the target receptor to reduce denaturation and prolonging stabilization of receptor in lipid bilayers without extra steps of reconstitution. This method yielded purified GLP1R in nanodiscs that could bind to GLP-1 and exendin-4 and activate Gs protein. This nanodisc purification method can potentially be a general strategy to routinely obtain purified family B GPCRs in the 10s of microgram amounts useful for spectroscopic analysis of receptor functions and activation mechanisms. PMID:28609478

  13. Discrimination between olfactory receptor agonists and non-agonists.

    PubMed

    Topin, Jérémie; de March, Claire A; Charlier, Landry; Ronin, Catherine; Antonczak, Serge; Golebiowski, Jérôme

    2014-08-11

    A joint approach combining free-energy calculations and calcium-imaging assays on the broadly tuned human 1G1 olfactory receptor is reported. The free energy of binding of ten odorants was computed by means of molecular-dynamics simulations. This state function allows separating the experimentally determined eight agonists from the two non-agonists. This study constitutes a proof-of-principle for the computational deorphanization of olfactory receptors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A human intervention study with foods containing natural Ah-receptor agonists does not significantly show AhR-mediated effects as measured in blood cells and urine.

    PubMed

    de Waard, Pim W J; Peijnenburg, Ad A C M; Baykus, Hakan; Aarts, Jac M M J G; Hoogenboom, Ron L A P; van Schooten, Frederik J; de Kok, Theo M C M

    2008-10-22

    Binding and activation of the aryl hydrocarbon receptor (AhR) is thought to be an essential step in the toxicity of the environmental pollutants dioxins and dioxin-like PCBs. However, also a number of natural compounds, referred to as NAhRAs (natural Ah-receptor agonists), which are present in, for example, fruits and vegetables, can bind and activate this receptor. To study their potential effects in humans, we first investigated the effect of the prototypical AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on gene expression in ex vivo exposed freshly isolated human lymphocytes, and compared the resulting gene expression profile with those caused by the well-known NAhRA indolo[3,2-b]carbazole (ICZ), originating from cruciferous vegetables, and by a hexane extract of NAhRA-containing grapefruit juice (GJE). Only ICZ induced a gene expression profile similar to TCDD in the lymphocytes, and both significantly up-regulated CYP1B1 and TIPARP (TCDD-inducible poly (ADP-ribose) polymerase) mRNA. Next, we performed a human intervention study with NAhRA-containing cruciferous vegetables and grapefruit juice. The expression of the prototypical AhR-responsive genes CYP1A1, CYP1B1 and NQO1 in whole blood cells and in freshly isolated lymphocytes was not significantly affected. Also enzyme activities of CYP1A2, CYP2A6, N-acetyltransferase 2 (NAT2) and xanthine oxidase (XO), as judged by caffeine metabolites in urine, were unaffected, except for a small down-regulation of NAT2 activity by grapefruit juice. Examination of blood plasma with DR CALUX showed a 12% increased AhR agonist activity 3 and 24 h after consumption of cruciferous vegetables, but did not show a significant effect of grapefruit juice consumption. We conclude that intake of NAhRAs from food may result in minor AhR-related effects measurable in human blood and urine.

  15. Effects of interleukin-1 receptor antagonist (IL-1Ra) gene 86 bp VNTR polymorphism on recurrent pregnancy loss: a case-control study.

    PubMed

    Hajizadeh, Yasamin Sayed; Emami, Elina; Nottagh, Marina; Amini, Zahra; Maroufi, Nazila Fathi; Azimian, Saba Haj; Isazadeh, Alireza

    2017-05-26

    Objective Recurrent pregnancy loss (RPL) is a heterogeneous disease which is defined as two or more consecutive fetal losses during early pregnancy. Interleukin-1 receptor antagonist (IL-1Ra) is a anti-inflammatory cytokine, which inhibits IL-1 activity by binding to its receptors. The aim of this study was to investigate the association between RPL and IL-1Ra intron 2 polymorphism (86 bp VNTR) in Iranian women. Materials and methods In this case control study, genetic polymorphism was studied in 140 RPL patients and 140 healthy women as controls. Genomic DNA was extracted from the blood samples and polymorphism analysis was performed using the polymerase chain reaction (PCR) method. Finally, the data obtained were analyzed by statistical software. Results We found an increased frequency of the IL-1Ra 1/1 genotype in the case group compared to the control group. Whereas, the frequency of IL-1Ra genotype 1/2 was higher in control group than in the case group. However, we did not observe an association between IL-1Ra 86 bp VNTR polymorphism in intron 2 and RPL patients (p > 0.05). Conclusion IL-1Ra VNTR polymorphism may not be a genetic factor for RPL. However, investigation of IL-1Ra polymorphism was recommended in other populations and patients with recurrent pregnancy loss.

  16. Quality goal attainment and maintenance in patients with type II diabetes mellitus initiated on canagliflozin or a glucagon-like peptide-1 receptor agonist in an actual practice setting.

    PubMed

    Wysham, Carol H; Pilon, Dominic; Ingham, Mike; Lafeuille, Marie-Hélène; Emond, Bruno; Kamstra, Rhiannon; Pfeifer, Michael; Lefebvre, Patrick

    2018-06-01

    To compare achievement of quality goals (HbA1c, weight loss/body mass index [BMI], systolic blood pressure [SBP]), including maintaining HbA1c, between patients with type 2 diabetes mellitus (T2DM) treated with canagliflozin 300 mg (CANA) or a GLP-1 in an actual practice setting. Adults with T2DM newly initiated on CANA or a GLP-1 were identified from the IQVIA TM Real-World Data Electronic Medical Records-US database (2012Q2-2016Q1). To account for differences in baseline characteristics, inverse probability of treatment weighting was used. Outcomes were compared using Cox models (hazard ratios [HRs] and 95% confidence intervals [CIs]) and Kaplan-Meier analyses. CANA (n = 11,435) and GLP-1 (n = 11,582) cohorts had similar attainment of HbA1c < 8.0% (64 mmol/mol) and HbA1c < 9.0% (75 mmol/mol; HbA1c < 8.0%: HR [CI] = 0.98 [0.91-1.06]; HbA1c < 9.0%: HR [CI] = 1.02 [0.93-1.12]), while GLP-1 patients were 10% more likely to achieve HbA1c < 7.0% (53 mmol/mol). CANA and GLP-1 patients were similar in maintaining HbA1c < 7.0%, < 8.0%, or <9.0%, achieving weight loss ≥5% (HR [CI] = 1.05 [0.99-1.12]), achieving BMI <30 kg/m 2 (HR [CI] = 1.11 [0.98-1.27]), and achieving SBP <140 mmHg (HR [CI] = 1.07 [0.98-1.17]). CANA patients were 30% less likely to discontinue treatment, 28% less likely to have a prescription for a new anti-hyperglycemic, and 17-21% less likely to fail to maintain HbA1c < 8.0% or 9.0% or have a prescription for a new anti-hyperglycemic (composite outcome) vs GLP-1. No significant difference was observed for the composite outcome using the HbA1c < 7.0% threshold. This retrospective study in an actual practice setting showed that CANA patients were generally as likely as GLP-1 patients to achieve HbA1c, weight, and blood pressure thresholds, and to maintain glycemic control while being less likely to discontinue treatment and/or have a new anti-hyperglycemic prescribed.

  17. Gingerols: a novel class of vanilloid receptor (VR1) agonists

    PubMed Central

    Dedov, Vadim N; Tran, Van H; Duke, Colin C; Connor, Mark; Christie, MacDonald J; Mandadi, Sravan; Roufogalis, Basil D

    2002-01-01

    Gingerols, the pungent constituents of ginger, were synthesized and assessed as agonists of the capsaicin-activated VR1 (vanilloid) receptor. [6]-Gingerol and [8]-gingerol evoked capsaicin-like intracellular Ca2+ transients and ion currents in cultured DRG neurones. These effects of gingerols were blocked by capsazepine, the VR1 receptor antagonist. The potency of gingerols increased with increasing size of the side chain and with the overall hydrophobicity in the series. We conclude that gingerols represent a novel class of naturally occurring VR1 receptor agonists that may contribute to the medicinal properties of ginger, which have been known for centuries. The gingerol structure may be used as a template for the development of drugs acting as moderately potent activators of the VR1 receptor. PMID:12411409

  18. GLP-2 potentiates L-type CA2+ channel activity associated with stimulated glucose uptake in hippocampal neurons

    USDA-ARS?s Scientific Manuscript database

    Glucagon-like peptide-2 (GLP-2) is a neuropeptide secreted from endocrine cells in the gut and neurons in the brain. GLP-2 stimulates intestinal crypt cell proliferation and mucosal blood flow while decreasing gastric emptying and gut motility. However, a GLP-2-mediated signaling network has not bee...

  19. Molecular Integration of Incretin and Glucocorticoid Action Reverses Immunometabolic Dysfunction and Obesity.

    PubMed

    Quarta, Carmelo; Clemmensen, Christoffer; Zhu, Zhimeng; Yang, Bin; Joseph, Sini S; Lutter, Dominik; Yi, Chun-Xia; Graf, Elisabeth; García-Cáceres, Cristina; Legutko, Beata; Fischer, Katrin; Brommage, Robert; Zizzari, Philippe; Franklin, Bernardo S; Krueger, Martin; Koch, Marco; Vettorazzi, Sabine; Li, Pengyun; Hofmann, Susanna M; Bakhti, Mostafa; Bastidas-Ponce, Aimée; Lickert, Heiko; Strom, Tim M; Gailus-Durner, Valerie; Bechmann, Ingo; Perez-Tilve, Diego; Tuckermann, Jan; Hrabě de Angelis, Martin; Sandoval, Darleen; Cota, Daniela; Latz, Eicke; Seeley, Randy J; Müller, Timo D; DiMarchi, Richard D; Finan, Brian; Tschöp, Matthias H

    2017-10-03

    Chronic inflammation has been proposed to contribute to the pathogenesis of diet-induced obesity. However, scarce therapeutic options are available to treat obesity and the associated immunometabolic complications. Glucocorticoids are routinely employed for the management of inflammatory diseases, but their pleiotropic nature leads to detrimental metabolic side effects. We developed a glucagon-like peptide-1 (GLP-1)-dexamethasone co-agonist in which GLP-1 selectively delivers dexamethasone to GLP-1 receptor-expressing cells. GLP-1-dexamethasone lowers body weight up to 25% in obese mice by targeting the hypothalamic control of feeding and by increasing energy expenditure. This strategy reverses hypothalamic and systemic inflammation while improving glucose tolerance and insulin sensitivity. The selective preference for GLP-1 receptor bypasses deleterious effects of dexamethasone on glucose handling, bone integrity, and hypothalamus-pituitary-adrenal axis activity. Thus, GLP-1-directed glucocorticoid pharmacology represents a safe and efficacious therapy option for diet-induced immunometabolic derangements and the resulting obesity. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Add-on therapy with anagliptin in Japanese patients with type-2 diabetes mellitus treated with metformin and miglitol can maintain higher concentrations of biologically active GLP-1/total GIP and a lower concentration of leptin.

    PubMed

    Osonoi, Takeshi; Saito, Miyoko; Hariya, Natsuyo; Goto, Moritaka; Mochizuki, Kazuki

    2016-12-01

    Metformin, α-glucosidase inhibitors (α-GIs), and dipeptidyl peptidase 4 inhibitors (DPP-4Is) reduce hyperglycemia without excessive insulin secretion, and enhance postprandial plasma concentration of glucagon-like peptide-1 (GLP-1) in type-2 diabetes mellitus (T2DM) patients. We assessed add-on therapeutic effects of DPP-4I anagliptin in Japanese T2DM patients treated with metformin, an α-GI miglitol, or both drugs on postprandial responses of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), and on plasma concentration of the appetite-suppressing hormone leptin. Forty-two Japanese T2DM patients with inadequately controlled disease (HbA1c: 6.5%-8.0%) treated with metformin (n=14), miglitol (n=14) or a combination of the two drugs (n=14) received additional treatment with anagliptin (100mg, p.o., b.i.d.) for 52 weeks. We assessed glycemic control, postprandial responses of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), and on plasma concentration of leptin in those patients. Add-on therapy with anagliptin for 52 weeks improved glycemic control and increased the area under the curve of biologically active GLP-1 concentration without altering obesity indicators. Total GIP concentration at 52 weeks was reduced by add-on therapy in groups treated with miglitol compared with those treated with metformin. Add-on therapy reduced leptin concentrations. Add-on therapy with anagliptin in Japanese T2DM patients treated with metformin and miglitol for 52 weeks improved glycemic control and enhanced postprandial concentrations of active GLP-1/total GIP, and reduce the leptin concentration. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Effects of 5-HT1A Receptor Stimulation on D1 Receptor Agonist-Induced Striatonigral Activity and Dyskinesia in Hemiparkinsonian Rats

    PubMed Central

    2013-01-01

    Accumulating evidence supports the value of 5-HT1A receptor (5-HT1AR) agonists for dyskinesias that arise with long-term L-DOPA therapy in Parkinson’s disease (PD). Yet, how 5-HT1AR stimulation directly influences the dyskinetogenic D1 receptor (D1R)-expressing striatonigral pathway remains largely unknown. To directly examine this, one cohort of hemiparkinsonian rats received systemic injections of Vehicle + Vehicle, Vehicle + the D1R agonist SKF81297 (0.8 mg/kg), or the 5-HT1AR agonist ±8-OH-DPAT (1.0 mg/kg) + SKF81297. Rats were examined for changes in abnormal involuntary movements (AIMs), rotations, striatal preprodynorphin (PPD), and glutamic acid decarboxylase (GAD; 65 and 67) mRNA via RT-PCR. In the second experiment, hemiparkinsonian rats received intrastriatal pretreatments of Vehicle (aCSF), ±8-OH-DPAT (7.5 mM), or ±8-OH-DPAT + the 5-HT1AR antagonist WAY100635 (4.6 mM), followed by systemic Vehicle or SKF81297 after which AIMs, rotations, and extracellular striatal glutamate and nigral GABA efflux were measured by in vivo microdialysis. Results revealed D1R agonist-induced AIMs were reduced by systemic and intrastriatal 5-HT1AR stimulation while rotations were enhanced. Although ±8-OH-DPAT did not modify D1R agonist-induced increases in striatal PPD mRNA, the D1R/5-HT1AR agonist combination enhanced GAD65 and GAD67 mRNA. When applied locally, ±8-OH-DPAT alone diminished striatal glutamate levels while the agonist combination increased nigral GABA efflux. Thus, presynaptic 5-HT1AR stimulation may attenuate striatal glutamate levels, resulting in diminished D1R-mediated dyskinetic behaviors, but maintain or enhance striatal postsynaptic factors ultimately increasing nigral GABA levels and rotational activity. The current findings offer a novel mechanistic explanation for previous results concerning 5-HT1AR agonists for the treatment of dyskinesia. PMID:23496922

  2. Does a family history of RA influence the clinical presentation and treatment response in RA?

    PubMed

    Frisell, Thomas; Saevarsdottir, Saedis; Askling, Johan

    2016-06-01

    To assess whether family history of rheumatoid arthritis (RA), among the strongest risk factors for developing RA, also carries information on the clinical presentation and treatment response. The prospective Swedish Rheumatology register was linked to family history of RA, defined as diagnosed RA in any first-degree relative, ascertained through the Swedish Multi-Generation and Patient registers. Clinical presentation was examined among patients with early RA 2000-2011 (symptom onset <12 months before inclusion, N=6869), and response to methotrexate (MTX) monotherapy in the subset starting this treatment (N=4630). Response to tumour necrosis factor inhibitors (TNFi) was examined among all patients with RA starting a TNFi as the first biological disease-modifying antirheumatic drug 2000-2011 (N=9249). Association of family history with clinical characteristics, drug survival, European League Against Rheumatism (EULAR) response and change in disease activity at 3 and 6 months was estimated using linear and generalised logistic regression models. Correlation in relatives' response measures was also assessed. Patients with early RA with family history of RA were more often rheumatoid factor positive, but with no other clinically meaningful differences in their clinical presentation. Family history of RA did not predict response to MTX or TNFi, with the possible exception of no versus good EULAR response to TNFi at 6 months (OR=1.4, 95% CI 1.1 to 1.7). Having a relative who discontinued TNFi within a year increased the odds of doing the same (OR=3.7, 95% CI 1.8 to 7.5), although we found no significant familial correlations in change in disease activity measures. Family history of RA did not modify the clinical presentation of RA or predict response to standard treatment with MTX or TNFi. Treatment response, particularly drug survival, may itself be familial. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a

  3. Functional analysis RaZIP1 transporter of the ZIP family from the ectomycorrhizal Zn-accumulating Russula atropurpurea.

    PubMed

    Leonhardt, Tereza; Sácký, Jan; Kotrba, Pavel

    2018-04-01

    A search of R. atropurpurea transcriptome for sequences encoding the transporters of the Zrt-, Irt-like Protein (ZIP) family, which are in eukaryotes integral to Zn supply into cytoplasm, allowed the identification of RaZIP1 cDNA with a predicted product belonging to ZIP I subfamily; it was subjected to functional studies in mutant Saccharomyces cerevisiae strains. The expression of RaZIP1, but not RaZIP1 H208A or RaZIP1 H232A mutants lacking conserved-among-ZIPs transmembrane histidyls, complemented Zn uptake deficiency in zrt1Δzrt2Δ yeasts. RaZIP1 substantially increased cellular Zn uptake in this strain and added to Zn sensitivity in zrc1Δcot1Δ mutant. The Fe uptake deficiency in ftr1Δ strain was not rescued and Mn uptake was insufficient for toxicity in Mn-sensitive pmr1Δ yeasts. By contrast, RaZIP1 increased Cd sensitivity in yap1Δ strain and conferred Cd transport activity in yeasts, albeit with substantially lower efficiency compared to Zn transport. In metal uptake assays, the accumulation of Zn in zrt1Δzrt2Δ strain remained unaffected by Cd, Fe, and Mn present in 20-fold molar excess over Zn. Immunofluorescence microscopy detected functional hemagglutinin-tagged HA::RaZIP1 on the yeast cell protoplast periphery. Altogether, these data indicate that RaZIP1 is a high-affinity plasma membrane transporter specialized in Zn uptake, and improve the understanding of the cellular and molecular biology of Zn in R. atropurpurea that is known for its ability to accumulate remarkably high concentrations of Zn.

  4. Exenatide Is an Effective Antihyperglycaemic Agent in a Mouse Model of Wolfram Syndrome 1

    PubMed Central

    Sedman, Tuuli; Rünkorg, Kertu; Krass, Maarja; Luuk, Hendrik; Plaas, Mario; Vasar, Eero; Volke, Vallo

    2016-01-01

    Wolfram syndrome 1 is a very rare monogenic disease resulting in a complex of disorders including diabetes mellitus. Up to now, insulin has been used to treat these patients. Some of the monogenic forms of diabetes respond preferentially to sulphonylurea preparations. The aim of the current study was to elucidate whether exenatide, a GLP-1 receptor agonist, and glipizide, a sulphonylurea, are effective in a mouse model of Wolfram syndrome 1. Wolframin-deficient mice were used to test the effect of insulin secretagogues. Wolframin-deficient mice had nearly normal fasting glucose levels but developed hyperglycaemia after glucose challenge. Exenatide in a dose of 10 μg/kg lowered the blood glucose level in both wild-type and wolframin-deficient mice when administered during a nonfasted state and during the intraperitoneal glucose tolerance test. Glipizide (0.6 or 2 mg/kg) was not able to reduce the glucose level in wolframin-deficient animals. In contrast to other groups, wolframin-deficient mice had a lower insulin-to-glucose ratio during the intraperitoneal glucose tolerance test, indicating impaired insulin secretion. Exenatide increased the insulin-to-glucose ratio irrespective of genotype, demonstrating the ability to correct the impaired insulin secretion caused by wolframin deficiency. We conclude that GLP-1 agonists may have potential in the treatment of Wolfram syndrome-related diabetes. PMID:27069934

  5. miR-7-1 POTENTIATED ESTROGEN RECEPTOR AGONISTS FOR FUNCTIONAL NEUROPROTECTION IN VSC4.1 MOTONEURONS

    PubMed Central

    CHAKRABARTI, M.; BANIK, N. L.; RAY, S. K.

    2013-01-01

    Protection of motoneurons is an important goal in the treatment of spinal cord injury (SCI). We tested whether neuroprotective microRNAs (miRs) like miR-206, miR-17, miR-21, miR-7-1, and miR-106a could enhance efficacy of estrogen receptor (ER) agonists such as 1,3,5-tris (4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT, ERα agonist), Way200070 (WAY, ERβ agonist), and estrogen (EST, ERα and ERβ agonist) in preventing apoptosis in the calcium ionophore (CI) insulted VSC4.1 motoneurons. We determined that 200 nM CI induced 70% cell death. Treatment with 50 nM PPT, 100 nM WAY, and 150 nM EST induced overexpression of ERα, ERβ, and both receptors, respectively, at mRNA and protein levels. Treatment with ER agonists significantly upregulated miR-206, miR-17, and miR-7-1 in the CI insulted VSC4.1 motoneurons. Transfection with miR-206, miR-17, or miR-7-1 mimic potentiated WAY or EST to inhibit apoptosis in the CI insulted VSC4.1 motoneurons. Overexpression of miR-7-1 maximally increased efficacy of WAY and EST for down regulation of pro-apoptotic Bax and upregulation of anti-apoptotic Bcl-2. A search using miRDB indicated that miR-7-1 could inhibit expression of L-type Ca2+ channel protein alpha 1C (CPα1C). miR-7-1 overexpression and WAY or EST treatment down regulated CPα1C but upregulated p-Akt to trigger cell survival signaling. The same therapeutic strategy increased expression of the Ca2+/calmodulin-dependent protein kinase II beta (CaMKIIβ) and the phosphorylated cAMP response element binding protein (p-CREB) so as to promote Bcl-2 transcription. Whole cell membrane potential and mitochondrial membrane potential studies indicated that miR-7-1 highly potentiated EST to preserve functionality in the CI insulted VSC4.1 motoneurons. In conclusion, our data indicated that miR-7-1 most significantly potentiated efficacy of EST for functional neuroprotection and this therapeutic strategy could be used in the future to attenuate apoptosis of motoneurons in SCI. PMID

  6. Semaglutide for type 2 diabetes mellitus: a systematic review and meta-analysis.

    PubMed

    Andreadis, Panagiotis; Karagiannis, Thomas; Malandris, Konstantinos; Avgerinos, Ioannis; Liakos, Aris; Manolopoulos, Apostolos; Bekiari, Eleni; Matthews, David R; Tsapas, Apostolos

    2018-05-13

    To assess the efficacy and safety of semaglutide, a recently approved glucagon-like peptide 1 receptor agonist (GLP-1 RA) for type 2 diabetes. We searched major electronic databases and grey literature sources for randomised controlled trials comparing semaglutide with placebo or other antidiabetic agents. Primary outcome was change from baseline in HbA 1c . Secondary endpoints included change from baseline in body weight, blood pressure, heart rate, and incidence of hypoglycaemia, gastrointestinal adverse effects, pancreatitis and diabetic retinopathy. Six placebo-controlled and seven active-controlled studies with subcutaneous semaglutide were included. We identified only one trial with oral semaglutide. Compared with placebo, subcutaneous semaglutide 0.5 and 1 mg reduced HbA 1c by 1.01% (95% CI 0.56 to 1.47) and 1.38% (1.05 to 1.70) respectively. Both doses demonstrated superior glycaemic efficacy compared to other antidiabetic agents, including sitagliptin, exenatide, liraglutide, dulaglutide and insulin glargine. Semaglutide also had a beneficial effect on body weight (mean difference versus placebo -4.11 kg, 95% CI -4.85 to -3.37 for semaglutide 1 mg) and systolic blood pressure. We did not observe increased hypoglycaemia rates with semaglutide; nevertheless, we noted an increased incidence of nausea, vomiting and diarrhoea. Cases of pancreatitis were infrequent and odds ratio for diabetic retinopathy compared with placebo was 1.32 (95% CI 0.98 to 1.77). Semaglutide is a potent once-weekly GLP-1 RA, reducing significantly HbA 1c , body weight and systolic blood pressure. However, it is associated with increased incidence of gastrointestinal adverse events. Results for pancreatitis and retinopathy require further assessment in post-approval pharmacovigilance studies. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  7. Synthesis and dual PPARalpha/delta agonist effects of 1,4-disubstituted 1,2,3-triazole analogues of GW 501516.

    PubMed

    Ciocoiu, Calin C; Nikolić, Natasa; Nguyen, Huyen Hoa; Thoresen, G Hege; Aasen, Arne J; Hansen, Trond Vidar

    2010-07-01

    Ten 1,4-disubstituted 1,2,3-triazoles 2a-2j were prepared and tested for their ability to increase oleic acid oxidation in human myotubes using a high-throughput multiwell assay. Compounds 2e (2-{4-[(1-(3-fluoro-4-(trifluoromethyl)phenyl)-1H-1,2,3-triazol-4-yl)methylthio]-2-methylphenoxy}acetic acid) and 2i (2-{4-[(1-(3-chloro-4-(trifluoromethoxy)phenyl)-1H-1,2,3-triazol-4-yl)methylthio]-2-methylphenoxy}acetic acid) exhibited potent agonist activities. Compounds 2e and 2i also exhibited powerful agonist effects for both PPARalpha and PPARdelta in a luciferase-based assay. Consequently, these triazoles can be categorized as dual PPAR agonists. Copyright (c) 2010 Elsevier Masson SAS. All rights reserved.

  8. Expression of cholecystokinin2-receptor in rat and human L cells and the stimulation of glucagon-like peptide-1 secretion by gastrin treatment.

    PubMed

    Cao, Yang; Cao, Xun; Liu, Xiao-Min

    2015-03-01

    Gastrin is a gastrointestinal hormone secreted by G cells. Hypergastrinemia can improve blood glucose and glycosylated hemoglobin levels. These positive effects are primarily due to the trophic effects of gastrin on β-cells. In recent years, many receptors that regulate secretion of glucagon-like peptide 1 (GLP-1) have been identified in enteroendocrine L cell lines. This led us to hypothesize that, in addition to the trophic effects of gastrin on β-cells, L cells also express cholecystokinin2-receptor (CCK2R), which may regulate GLP-1 secretion and have synergistic effects on glucose homeostasis. Our research provides a preliminary analysis of CCK2R expression and the stimulating effect of gastrin treatment on GLP-1 secretion in a human endocrine L cell line, using RT-PCR, Western blot, immunocytochemistry, and ELISA analyses. The expression of proglucagon and prohormone convertase 3, which regulate GLP-1 biosynthesis, were also analyzed by real-time PCR. Double immunofluorescence labeling was utilized to assess the intracellular localization of CCK2R and GLP-1 in L cells harvested from rat colon tissue. Our results showed that CCK2R was expressed in both the human L cell line and the rat L cells. We also showed that treatment with gastrin, a CCK2R agonist, stimulated the secretion of GLP-1, and that this effect was likely due to increased expression of proglucagon and PCSK1 (also known as prohormone convertase 3 (PC3 gene)). These results not only provide a basis for the role gastrin may play in intestinal L cells, and may also provide the basis for the development of a method of gastrin-mediated glycemic regulation. Copyright © 2014 Elsevier GmbH. All rights reserved.

  9. Distinct roles of KAP1, HP1 and G9a/GLP in silencing of the two-cell-specific retrotransposon MERVL in mouse ES cells

    PubMed Central

    2013-01-01

    Background In mouse embryonic stem cells (mESCs), transcriptional silencing of numerous class I and II endogenous retroviruses (ERVs), including IAP, ETn and MMERVK10C, is dependent upon the H3K9 methyltransferase (KMTase) SETDB1/ESET and its binding partner KAP1/TRIM28. In contrast, the H3K9 KMTases G9a and GLP and HP1 proteins are dispensable for this process. Intriguingly, MERVL retroelements are actively transcribed exclusively in the two-cell (2C) embryo, but the molecular basis of silencing of these class III ERVs at later developmental stages has not been systematically addressed. Results Here, we characterized the roles of these chromatin factors in MERVL silencing in mESCs. While MMERVK10C and IAP ERVs are bound by SETDB1 and KAP1 and are induced following their deletion, MERVL ERVs show relatively low levels of SETDB1 and KAP1 binding and are upregulated exclusively following KAP1 depletion, indicating that KAP1 influences MERVL expression independent of SETDB1. In contrast to class I and class II ERVs, MERVL and MERVL LTR-driven genic transcripts are also upregulated following depletion of G9a or GLP, and G9a binds directly to these ERVs. Consistent with a direct role for H3K9me2 in MERVL repression, these elements are highly enriched for G9a-dependent H3K9me2, and catalytically active G9a is required for silencing of MERVL LTR-driven transcripts. MERVL is also derepressed in HP1α and HP1β KO ESCs. However, like KAP1, HP1α and HP1β are only modestly enriched at MERVL relative to IAP LTRs. Intriguingly, as recently shown for KAP1, RYBP, LSD1 and G9a-deficient mESCs, many genes normally expressed in the 2C embryo are also induced in HP1 KO mESCs, revealing that aberrant expression of a subset of 2C-specific genes is a common feature in each of these KO lines. Conclusions Our results indicate that G9a and GLP, which are not required for silencing of class I and II ERVs, are recruited to MERVL elements and play a direct role in silencing of these class

  10. Lipophilic Prodrugs of FR900098 Are Antimicrobial against Francisella novicida In Vivo and In Vitro and Show GlpT Independent Efficacy

    PubMed Central

    McKenney, Elizabeth S.; Sargent, Michelle; Khan, Hameed; Uh, Eugene; Jackson, Emily R.; Jose, Géraldine San; Couch, Robin D.; Dowd, Cynthia S.; van Hoek, Monique L.

    2012-01-01

    Bacteria, plants, and algae produce isoprenoids through the methylerythritol phosphate (MEP) pathway, an attractive pathway for antimicrobial drug development as it is present in prokaryotes and some lower eukaryotes but absent from human cells. The first committed step of the MEP pathway is catalyzed by 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR/MEP synthase). MEP pathway genes have been identified in many biothreat agents, including Francisella, Brucella, Bacillus, Burkholderia, and Yersinia. The importance of the MEP pathway to Francisella is demonstrated by the fact that MEP pathway mutations are lethal. We have previously established that fosmidomycin inhibits purified MEP synthase (DXR) from F. tularensis LVS. FR900098, the acetyl derivative of fosmidomycin, was found to inhibit the activity of purified DXR from F. tularensis LVS (IC50 = 230 nM). Fosmidomycin and FR900098 are effective against purified DXR from Mycobacterium tuberculosis as well, but have no effect on whole cells because the compounds are too polar to penetrate the thick cell wall. Fosmidomycin requires the GlpT transporter to enter cells, and this is absent in some pathogens, including M. tuberculosis. In this study, we have identified the GlpT homologs in F. novicida and tested transposon insertion mutants of glpT. We showed that FR900098 also requires GlpT for full activity against F. novicida. Thus, we synthesized several FR900098 prodrugs that have lipophilic groups to facilitate their passage through the bacterial cell wall and bypass the requirement for the GlpT transporter. One compound, that we termed “compound 1,” was found to have GlpT-independent antimicrobial activity. We tested the ability of this best performing prodrug to inhibit F. novicida intracellular infection of eukaryotic cell lines and the caterpillar Galleria mellonella as an in vivo infection model. As a lipophilic GlpT-independent DXR inhibitor, compound 1 has the potential to be a broad

  11. Discovery of Tetrahydropyrazolopyridine as Sphingosine 1-Phosphate Receptor 3 (S1P3)-Sparing S1P1 Agonists Active at Low Oral Doses.

    PubMed

    Demont, Emmanuel H; Bailey, James M; Bit, Rino A; Brown, Jack A; Campbell, Colin A; Deeks, Nigel; Dowell, Simon J; Eldred, Colin; Gaskin, Pam; Gray, James R J; Haynes, Andrea; Hirst, David J; Holmes, Duncan S; Kumar, Umesh; Morse, Mary A; Osborne, Greg J; Renaux, Jessica F; Seal, Gail A L; Smethurst, Chris A; Taylor, Simon; Watson, Robert; Willis, Robert; Witherington, Jason

    2016-02-11

    FTY720 is the first oral small molecule approved for the treatment of people suffering from relapsing-remitting multiple sclerosis. It is a potent agonist of the S1P1 receptor, but its lack of selectivity against the S1P3 receptor has been linked to most of the cardiovascular side effects observed in the clinic. These findings have triggered intensive efforts toward the identification of a second generation of S1P3-sparing S1P1 agonists. We have recently disclosed a series of orally active tetrahydroisoquinoline (THIQ) compounds matching these criteria. In this paper we describe how we defined and implemented a strategy aiming at the discovery of selective structurally distinct follow-up agonists. This effort culminated with the identification of a series of orally active tetrahydropyrazolopyridines.

  12. Aspergillus glaucus Aquaglyceroporin Gene glpF Confers High Osmosis Tolerance in Heterologous Organisms.

    PubMed

    Liu, Xiao-Dan; Wei, Yi; Zhou, Xiao-Yang; Pei, Xue; Zhang, Shi-Hong

    2015-10-01

    Aquaglyceroporins (GlpFs) that transport glycerol along with water and other uncharged solutes are involved in osmoregulation in myriad species. Fungal species form a large group of eukaryotic organisms, and their GlpFs may be diverse, exhibiting various activities. However, few filamentous fungal GlpFs have been biologically investigated. Here, a glpF gene from the halophilic fungus Aspergillus glaucus (AgglpF) was verified to be a channel of water or glycerol in Xenopus laevis oocytes and was further functionally analyzed in three heterologous systems. In Saccharomyces cerevisiae, cells overexpressing AgglpF possessed significant tolerance of drought, salt, and certain metal ions. AgglpF was then characterized in the filamentous fungus of Neurospora crassa. Based on the N. crassa aquaporin gene (NcAQP) disruption mutant (the Δaqp mutant), a series of complementary strains carrying NcAQP and AgglpF and three asparagine-proline-alanine-gene (NPA)-deleted AgglpF fragments were created. As revealed by salt resistance analysis, the AgglpF complementary strain possessed the highest salt resistance among the tested strains. In addition, the intracellular glycerol content in the AgglpF complementary strain was markedly higher than that in the other strains. The AgGlpF-green fluorescent protein (GFP) fusion protein was subcellularly localized in the plasma membrane of onion epidermal cells, suggesting that AgglpF functions in plants. Indeed, when AgglpF was expressed in Arabidopsis thaliana, transgenic lines survived under conditions of high osmotic stress and under conditions of drought stress in particular. Overall, our results revealed that AgGlpF as a water/glycerol transporter is required for survival of both fungi and plants under conditions of high osmotic stress and may have value in applications in genetic engineering for generating high salt and drought resistance. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  13. Aspergillus glaucus Aquaglyceroporin Gene glpF Confers High Osmosis Tolerance in Heterologous Organisms

    PubMed Central

    Liu, Xiao-Dan; Wei, Yi; Zhou, Xiao-Yang; Pei, Xue

    2015-01-01

    Aquaglyceroporins (GlpFs) that transport glycerol along with water and other uncharged solutes are involved in osmoregulation in myriad species. Fungal species form a large group of eukaryotic organisms, and their GlpFs may be diverse, exhibiting various activities. However, few filamentous fungal GlpFs have been biologically investigated. Here, a glpF gene from the halophilic fungus Aspergillus glaucus (AgglpF) was verified to be a channel of water or glycerol in Xenopus laevis oocytes and was further functionally analyzed in three heterologous systems. In Saccharomyces cerevisiae, cells overexpressing AgglpF possessed significant tolerance of drought, salt, and certain metal ions. AgglpF was then characterized in the filamentous fungus of Neurospora crassa. Based on the N. crassa aquaporin gene (NcAQP) disruption mutant (the Δaqp mutant), a series of complementary strains carrying NcAQP and AgglpF and three asparagine-proline-alanine-gene (NPA)-deleted AgglpF fragments were created. As revealed by salt resistance analysis, the AgglpF complementary strain possessed the highest salt resistance among the tested strains. In addition, the intracellular glycerol content in the AgglpF complementary strain was markedly higher than that in the other strains. The AgGlpF-green fluorescent protein (GFP) fusion protein was subcellularly localized in the plasma membrane of onion epidermal cells, suggesting that AgglpF functions in plants. Indeed, when AgglpF was expressed in Arabidopsis thaliana, transgenic lines survived under conditions of high osmotic stress and under conditions of drought stress in particular. Overall, our results revealed that AgGlpF as a water/glycerol transporter is required for survival of both fungi and plants under conditions of high osmotic stress and may have value in applications in genetic engineering for generating high salt and drought resistance. PMID:26209670

  14. Experimental transmission of AA amyloidosis by injecting the AA amyloid protein into interleukin-1 receptor antagonist knockout (IL-1raKO) mice.

    PubMed

    Watanabe, K; Uchida, K; Chambers, J K; Tei, M; Shoji, A; Ushio, N; Nakayama, H

    2015-05-01

    The incidence of AA amyloidosis is high in humans with rheumatoid arthritis and several animal species, including cats and cattle with prolonged inflammation. AA amyloidosis can be experimentally induced in mice using severe inflammatory stimuli and a coinjection of AA amyloid; however, difficulties have been associated with transmitting AA amyloidosis to a different animal species, and this has been attributed to the "species barrier." The interleukin-1 receptor antagonist knockout (IL-1raKO) mouse, a rodent model of human rheumatoid arthritis, has been used in the transmission of AA amyloid. When IL-1raKO and BALB/c mice were intraperitoneally injected with mouse AA amyloid together with a subcutaneous pretreatment of 2% AgNO3, all mice from both strains that were injected with crude or purified murine AA amyloid developed AA amyloidosis. However, the amyloid index, which was determined by the intensity of AA amyloid deposition, was significantly higher in IL-1raKO mice than in BALB/c mice. When IL-1raKO and BALB/c mice were injected with crude or purified bovine AA amyloid together with the pretreatment, 83% (5/6 cases) and 38% (3/8 cases) of IL-1raKO mice and 17% (1/6 cases) and 0% (0/6 cases) of BALB/c mice, respectively, developed AA amyloidosis. Similarly, when IL-1raKO and BALB/c mice were injected with crude or purified feline AA amyloid, 33% (2/6 cases) and 88% (7/8 cases) of IL-1raKO mice and 0% (0/6 cases) and 29% (2/6 cases) of BALB/c mice, respectively, developed AA amyloidosis. These results indicated that IL-1raKO mice are a useful animal model for investigating AA amyloidogenesis. © The Author(s) 2014.

  15. [The transfection and expression of IL-1ra gene to the rabbit cornea in situ via cation polymer mediation].

    PubMed

    Yuan, Jin; Chen, Jia-qi; Zhou, Shi-you; Liu, Zu-guo; Wang, Zhi-chong; Gu, Jian-jun

    2006-08-01

    To investigate the efficiency and safety of transfection of PEGFP-IL-1ra plasmid via cation polymer mediation (poly-ethylenimine, PEI) by injection into the corneal stroma. Human IL-1ra cDNA fragments were cloned by RT-PCR. Plasmid PEGFP-hIL-1ra recombinants were constructed and transferred into corneal endothelial cells (CEC) via cation polymer mediation. Expression of IL-1ra mRNA and IL-1ra was detected by green fluorescent protein (GFP) and Western-blotting. In the experiment group, 20 microl preparation containing 10 microg plasmid PEGFP-hIL-1ra recombinants and PEI-in-vivo was injected into the corneal stroma of Wistar rats (n = 30). Equivalent PEI-in-vivo solution was injected into another 15 corneas as the controls. Corneas were harvested at different time points (day 1, 3, 6, 14 and 21) after injection. The changes of tissue structure and function after IL-1ra in situ transfection were studied by HE staining, transmission electron microscopy, trypan blue-alizarin red staining and immunohistochemistry. The location and intensity of IL-1ra-GFP fusion protein expression were monitored by fluorescence microscopy. The size of the RT-PCR product of hIL-1ra fragments was approximately 500 bp in agarose gel electrophoresis. Restrictive enzyme digestion analysis of PstI, BamHI and DNA sequence analysis showed that expression of plasmid PEGFP-hIL-1ra recombinants had been constructed successfully. Twelve hours after the transfection of PEGFP-hIL-1ra, GFP fluorescence was detected in 10% - 15% endothelial cells. IL-1ra protein (RMW: 44,000) was detected by Western-blotting. In PEGFP-hIL-1ra treated group, fluorescence was appeared at day 1 in cornea basal epithelial cells, peaked at day 6 in whole cornea, began to weaken at day 14, and only weak fluorescence remained in cornea epithelial cells at day 21. No fluorescence appeared in the control group. No significant pathologic changes could be found in HE stained cornea tissues in both transfected group and the

  16. Seasonal changes in submarine groundwater discharge to coastal salt ponds estimated using 226Ra and 228Ra as tracers

    USGS Publications Warehouse

    Hougham, A.L.; Moran, S.B.; Masterson, J.P.; Kelly, R.P.

    2008-01-01

    Submarine groundwater discharge (SGD) to coastal southern Rhode Island was estimated from measurements of the naturally-occurring radioisotopes 226Ra (t1/2 = 1600??y) and 228Ra (t1/2 = 5.75??y). Surface water and porewater samples were collected quarterly in Winnapaug, Quonochontaug, Ninigret, Green Hill, and Pt. Judith-Potter Ponds, as well as nearly monthly in the surface water of Rhode Island Sound, from January 2002 to August 2003; additional porewater samples were collected in August 2005. Surface water activities ranged from 12-83??dpm 100??L- 1 (60??dpm = 1??Bq) and 21-256??dpm 100??L- 1 for 226Ra and 228Ra, respectively. Porewater 226Ra activities ranged from 16-736??dpm 100??L- 1 (2002-2003) and 95-815??dpm 100??L- 1 (2005), while porewater 228Ra activities ranged from 23-1265??dpm 100??L- 1. Combining these data with a simple box model provided average 226Ra-based submarine groundwater fluxes ranging from 11-159??L m- 2 d- 1 and average 228Ra-derived fluxes of 15-259??L m- 2 d- 1. Seasonal changes in Ra-derived SGD were apparent in all ponds as well as between ponds, with SGD values of 30-472??L m- 2 d- 1 (Winnapaug Pond), 6-20??L m- 2 d- 1 (Quonochontaug Pond), 36-273??L m- 2 d- 1 (Ninigret Pond), 29-76??L m- 2 d- 1 (Green Hill Pond), and 19-83??L m- 2 d- 1 (Pt. Judith-Potter Pond). These Ra-derived fluxes are up to two orders of magnitude higher than results predicted by a numerical model of groundwater flow, estimates of aquifer recharge for the study period, and values published in previous Ra-based SGD studies in Rhode Island. This disparity may result from differences in the type of flow (recirculated seawater versus fresh groundwater) determined using each technique, as well as variability in porewater Ra activity. ?? 2007 Elsevier B.V. All rights reserved.

  17. Discovery of Dual-Action Membrane-Anchored Modulators of Incretin Receptors

    PubMed Central

    Fortin, Jean-Philippe; Chinnapen, Daniel; Beinborn, Martin; Lencer, Wayne; Kopin, Alan S.

    2011-01-01

    Background The glucose-dependent insulinotropic polypeptide (GIP) and the glucagon-like peptide-1 (GLP-1) receptors are considered complementary therapeutic targets for type 2 diabetes. Using recombinant membrane-tethered ligand (MTL) technology, the present study focused on defining optimized modulators of these receptors, as well as exploring how local anchoring influences soluble peptide function. Methodology/Principal Findings Serial substitution of residue 7 in membrane-tethered GIP (tGIP) led to a wide range of activities at the GIP receptor, with [G7]tGIP showing enhanced efficacy compared to the wild type construct. In contrast, introduction of G7 into the related ligands, tGLP-1 and tethered exendin-4 (tEXE4), did not affect signaling at the cognate GLP-1 receptor. Both soluble and tethered GIP and GLP-1 were selective activators of their respective receptors. Although soluble EXE4 is highly selective for the GLP-1 receptor, unexpectedly, tethered EXE4 was found to be a potent activator of both the GLP-1 and GIP receptors. Diverging from the pharmacological properties of soluble and tethered GIP, the newly identified GIP-R agonists, (i.e. [G7]tGIP and tEXE4) failed to trigger cognate receptor endocytosis. In an attempt to recapitulate the dual agonism observed with tEXE4, we conjugated soluble EXE4 to a lipid moiety. Not only did this soluble peptide activate both the GLP-1 and GIP receptors but, when added to receptor expressing cells, the activity persists despite serial washes. Conclusions These findings suggest that conversion of a recombinant MTL to a soluble membrane anchored equivalent offers a means to prolong ligand function, as well as to design agonists that can simultaneously act on more than one therapeutic target. PMID:21935440

  18. IL-1RA gene-transfected bone marrow-derived mesenchymal stem cells in APA microcapsules could alleviate rheumatoid arthritis.

    PubMed

    Hu, Jianhua; Li, Hongjian; Chi, Guanhao; Yang, Zhao; Zhao, Yi; Liu, Wei; Zhang, Chao

    2015-01-01

    In order to investigate the encapsulation of interleukin 1 receptor antagonist (IL-RA) gene-modified mesenchymal stem cells (MSCs) in alginate-poly-L-lysine (APA) microcapsules for the persistent delivery of interleukin 1 receptor antagonist (IL-RA) to treat Rheumatoid arthritis (RA). We transfect mesenchymal stem cells with IL-RA gene, and quantify the IL-RA proteins released from the encapsulated cells followed by microencapsulation of recombinant mesenchymal stem cells, and thus observe the permeability of APA microcapsules and evaluate clinical effects after induction and treatment of collagen-induced arthritis (CIA). The concentration of IL-RA in the supernatant was determined by IL-RA ELISA kit by run in technical triplicates using samples from three separate mice. Encapsulated IL-RA gene-transfected cells were capable of constitutive delivery of IL-RA proteins for at least 30 days. Moreover, the APA microcapsules could inhibit the permeation of fluorescein isothiocyanate-conjuncted immunoglobulin G. Also, it has been found that the APA microcapsules can significantly attenuate collagen induced arthritis after delivering of APA microcapsules to rats. Our results demonstrated that the nonautologous IL-RA gene-transfected stem cells are of potential utility for RA therapy.

  19. IL-1RA gene-transfected bone marrow-derived mesenchymal stem cells in APA microcapsules could alleviate rheumatoid arthritis

    PubMed Central

    Hu, Jianhua; Li, Hongjian; Chi, Guanhao; Yang, Zhao; Zhao, Yi; Liu, Wei; Zhang, Chao

    2015-01-01

    Objectives: In order to investigate the encapsulation of interleukin 1 receptor antagonist (IL-RA) gene-modified mesenchymal stem cells (MSCs) in alginate-poly-L-lysine (APA) microcapsules for the persistent delivery of interleukin 1 receptor antagonist (IL-RA) to treat Rheumatoid arthritis (RA). Methods: We transfect mesenchymal stem cells with IL-RA gene, and quantify the IL-RA proteins released from the encapsulated cells followed by microencapsulation of recombinant mesenchymal stem cells, and thus observe the permeability of APA microcapsules and evaluate clinical effects after induction and treatment of collagen-induced arthritis (CIA). The concentration of IL-RA in the supernatant was determined by IL-RA ELISA kit by run in technical triplicates using samples from three separate mice. Results: Encapsulated IL-RA gene-transfected cells were capable of constitutive delivery of IL-RA proteins for at least 30 days. Moreover, the APA microcapsules could inhibit the permeation of fluorescein isothiocyanate-conjuncted immunoglobulin G. Also, it has been found that the APA microcapsules can significantly attenuate collagen induced arthritis after delivering of APA microcapsules to rats. Conclusions: Our results demonstrated that the nonautologous IL-RA gene-transfected stem cells are of potential utility for RA therapy. PMID:25785047

  20. 228Ra and 226Ra Profiles from the Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Lin, H.; Chung, Y.; Lin, C.

    2005-05-01

    We previously reported the distributions of 228Ra and 226Ra in the northern South China Sea (SCS) which showed that both nuclides in surface waters were much higher than those in the open oceans because the SCS was enclosed mostly by landmasses which are known as sources of these nuclides. Large temporal and spectial variations were also observed probably due to the monsoons and intrusion of the Kuroshio Current. During a recent cruise conducted in the northern SCS in February, 2004, three vertical 228Ra profiles were measured by gamma spectrometry on the Ra isotopes which were concentrated first by the MnO2-impregnated acrylic fiber and then acid-washed as sample solution for counting. The two deep water 228Ra profiles are remarkably similar, showing high values in the surface layer and fairly uniform at about 10 to 13 dpm/100L below 200m depth but with a clear increase toward the bottom due to input from the underlying sediments. The shallow water profile on the shelf shows higher 228Ra values due to both vertical and horizontal mixing of the shelf water with additional source from the shore zone. Additional 228Ra profiles measured on samples from earlier cruises show that the deep water values may differ significantly (up to 5 dpm/100L) at the same location in different seasons or cruises. The associated 226Ra profiles are also variable but quite comparable to those in the northwest Pacific in deep water. 226Ra activities in the shallow water (less than 1000m depth) are higher in the SCS than in the open oceans. The 228Ra/226Ra activity ratios vary mostly from about 0.3 to 0.5 in the deep water. These values are much higher than those in the open oceans which are generally less than 0.1.

  1. A high carbohydrate, but not fat or protein meal attenuates postprandial ghrelin, PYY and GLP-1 responses in Chinese men

    PubMed Central

    Parvaresh Rizi, Ehsan; Loh, Tze Ping; Baig, Sonia; Chhay, Vanna; Huang, Shiqi; Caleb Quek, Jonathan; Tai, E. Shyong; Toh, Sue-Anne

    2018-01-01

    It is known that the macronutrient content of a meal has different impacts on the postprandial satiety and appetite hormonal responses. Whether obesity interacts with such nutrient-dependent responses is not well characterized. We examined the postprandial appetite and satiety hormonal responses after a high-protein (HP), high-carbohydrate (HC), or high-fat (HF) mixed meal. This was a randomized cross-over study of 9 lean insulin-sensitive (mean±SEM HOMA-IR 0.83±0.10) and 9 obese insulin-resistant (HOMA-IR 4.34±0.41) young (age 21–40 years), normoglycaemic Chinese men. We measured fasting and postprandial plasma concentration of glucose, insulin, active glucagon-like peptide-1 (GLP-1), total peptide-YY (PYY), and acyl-ghrelin in response to HP, HF, or HC meals. Overall postprandial plasma insulin response was more robust in the lean compared to obese subjects. The postprandial GLP-1 response after HF or HP meal was higher than HC meal in both lean and obese subjects. In obese subjects, HF meal induced higher response in postprandial PYY compared to HC meal. HP and HF meals also suppressed ghrelin greater compared to HC meal in the obese than lean subjects. In conclusion, a high-protein or high-fat meal induces a more favorable postprandial satiety and appetite hormonal response than a high-carbohydrate meal in obese insulin-resistant subjects. PMID:29385178

  2. Dipeptidyl peptidase IV inhibition potentiates amino acid- and bile acid-induced bicarbonate secretion in rat duodenum

    PubMed Central

    Inoue, Takuya; Wang, Joon-Ho; Higashiyama, Masaaki; Rudenkyy, Sergiy; Higuchi, Kazuhide; Guth, Paul H.; Engel, Eli; Kaunitz, Jonathan D.

    2012-01-01

    Intestinal endocrine cells release gut hormones, including glucagon-like peptides (GLPs), in response to luminal nutrients. Luminal l-glutamate (l-Glu) and 5′-inosine monophosphate (IMP) synergistically increases duodenal HCO3− secretion via GLP-2 release. Since L cells express the bile acid receptor TGR5 and dipeptidyl peptidase (DPP) IV rapidly degrades GLPs, we hypothesized that luminal amino acids or bile acids stimulate duodenal HCO3− secretion via GLP-2 release, which is enhanced by DPPIV inhibition. We measured HCO3− secretion with pH and CO2 electrodes using a perfused rat duodenal loop under isoflurane anesthesia. l-Glu (10 mM) and IMP (0.1 mM) were luminally coperfused with or without luminal perfusion (0.1 mM) or intravenous (iv) injection (3 μmol/kg) of the DPPIV inhibitor NVP728. The loop was also perfused with a selective TGR5 agonist betulinic acid (BTA, 10 μM) or the non-bile acid type TGR5 agonist 3-(2-chlorophenyl)-N-(4-chlorophenyl)-N,5-dimethylisoxazole-4-carboxamide (CCDC; 10 μM). DPPIV activity visualized by use of the fluorogenic substrate was present on the duodenal brush border and submucosal layer, both abolished by the incubation with NVP728 (0.1 mM). An iv injection of NVP728 enhanced l-Glu/IMP-induced HCO3− secretion, whereas luminal perfusion of NVP728 had no effect. BTA or CCDC had little effect on HCO3− secretion, whereas NVP728 iv markedly enhanced BTA- or CCDC-induced HCO3− secretion, the effects inhibited by a GLP-2 receptor antagonist. Coperfusion of the TGR5 agonist enhanced l-Glu/IMP-induced HCO3− secretion with the enhanced GLP-2 release, suggesting that TGR5 activation amplifies nutrient sensing signals. DPPIV inhibition potentiated luminal l-Glu/IMP-induced and TGR5 agonist-induced HCO3− secretion via a GLP-2 pathway, suggesting that the modulation of the local concentration of the endogenous secretagogue GLP-2 by luminal compounds and DPPIV inhibition helps regulate protective duodenal HCO3− secretion

  3. Is insulin the preferred treatment for HbA1c >9%?

    PubMed

    Bloomgarden, Zachary

    2017-09-01

    approaches are more effective than monotherapy, with a combination regimen the HbA1c reduction will not be directly additive, because the expected reduction decreases at lower baseline HbA1c levels. As an example of this, administration of canagliflozin 300 mg daily to patients with baseline HbA1c >9% reduced levels from 9.6% by 1.8%, whereas at a baseline HbA1c of 10% either canagliflozin 300 mg or metformin 2 g/day reduced HbA1c by 2%; the addition of both agents led to an HbA1c reduction by somewhat less than 3%, which appears concordant with a reduction by the second agent from approximately 8% (10% to 2%). Similar less-than-additive effects of the addition of exenatide QW to dapagliflozin have been reported, with HbA1c reduction from a baseline of 10.0%-10.1% of 1.9% and 1.6% with the individual agents, respectively, and a reduction of 2.2% with their combination. However, one may consider these approaches inferior to the expected HbA1c reduction with insulin, suggesting that insulin should, indeed, be the preferred treatment for people with T2D and HbA1c >9%. Rather, studies comparing basal insulin directly with glucagon-like peptide-1 (GLP-1) receptor agonists (RA) suggest that the latter agents may offer superior benefit. The Diabetes Therapy Utilization: Researching Changes in HBA1C, Weight, and Other Factors Through Intervention with Exenatide Once Weekly (DURATION)-3 and Liraglutide Effect and Action in Diabetes (LEAD)-5 studies compared exenatide QW and liraglutide, respectively, with insulin glargine. Those study participants in the highest quartile of baseline HbA1c had levels ≥9.0% and ≥8.9%, with the GLP-1RA leading to 0.3% and 0.2% greater reductions in HbA1c, respectively, than insulin glargine. Another study comparing T2D patients receiving oral agents given liraglutide with those given insulin glargine showed that those in the highest baseline HbA1c quartile (mean 10.6%) had an HbA1c reduction of 3.1% with either agent. In the exenatide QW study

  4. MiR-7-1 potentiated estrogen receptor agonists for functional neuroprotection in VSC4.1 motoneurons.

    PubMed

    Chakrabarti, M; Banik, N L; Ray, S K

    2014-01-03

    Protection of motoneurons is an important goal in the treatment of spinal cord injury (SCI). We tested whether neuroprotective microRNAs (miRs) like miR-206, miR-17, miR-21, miR-7-1, and miR-106a could enhance efficacy of estrogen receptor (ER) agonists such as 1,3,5-tris (4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT, ERα agonist), Way200070 (WAY, ERβ agonist), and estrogen (EST, ERα and ERβ agonist) in preventing apoptosis in the calcium ionophore (CI)-insulted ventral spinal cord 4.1 (VSC4.1) motoneurons. We determined that 200 nM CI induced 70% cell death. Treatment with 50 nM PPT, 100 nM WAY, and 150 nM EST induced overexpression of ERα, ERβ, and both receptors, respectively, at mRNA and protein levels. Treatment with ER agonists significantly upregulated miR-206, miR-17, and miR-7-1 in the CI-insulted VSC4.1 motoneurons. Transfection with miR-206, miR-17, or miR-7-1 mimic potentiated WAY or EST to inhibit apoptosis in the CI-insulted VSC4.1 motoneurons. Overexpression of miR-7-1 maximally increased efficacy of WAY and EST for down regulation of pro-apoptotic Bax and upregulation of anti-apoptotic Bcl-2. A search using microRNA database (miRDB) indicated that miR-7-1 could inhibit the expression of L-type Ca(2+) channel protein alpha 1C (CPα1C). miR-7-1 overexpression and WAY or EST treatment down regulated CPα1C but upregulated p-Akt to trigger cell survival signaling. The same therapeutic strategy increased expression of the Ca(2+)/calmodulin-dependent protein kinase II beta (CaMKIIβ) and the phosphorylated cAMP response element binding protein (p-CREB) so as to promote Bcl-2 transcription. Whole cell membrane potential and mitochondrial membrane potential studies indicated that miR-7-1 highly potentiated EST to preserve functionality in the CI-insulted VSC4.1 motoneurons. In conclusion, our data indicated that miR-7-1 most significantly potentiated efficacy of EST for functional neuroprotection and this therapeutic strategy could be used in the future

  5. Acute increases in serum colonic short-chain fatty acids elicited by inulin do not increase GLP-1 or PYY responses but may reduce ghrelin in lean and overweight humans.

    PubMed

    Rahat-Rozenbloom, S; Fernandes, J; Cheng, J; Wolever, T M S

    2017-08-01

    Colonic fermentation of dietary fibre to short-chain fatty acids (SCFA) influences appetite hormone secretion in animals, but SCFA production is excessive in obese animals. This suggests there may be resistance to the effect of SCFA on appetite hormones in obesity. To determine the effects of inulin (IN) and resistant starch (RS) on postprandial SCFA, and gut hormone (glucagon-like peptide (GLP-1), peptide-tyrosine-tyrosine (PYY) and ghrelin) responses in healthy overweight/obese (OWO) vs lean (LN) humans. Overnight-fasted participants (13 OWO and 12 LN) consumed 300 ml water containing 75 g glucose (GLU) as control or 75 g GLU plus 24 g IN, or 28.2 g RS using a randomised, single-blind, cross-over design. Blood for appetite hormones and SCFA was collected at intervals over 6 h. A standard lunch was served 4 h after the test drink. Relative to GLU, IN, but not RS, significantly increased SCFA areas under the curve (AUC) from 4-6 h (AUC 4-6 ). Neither IN nor RS affected GLP-1 or PYY-AUC 4-6 . Although neither IN nor RS reduced ghrelin-AUC 4-6 compared with GLU, ghrelin at 6 h after IN was significantly lower than that after GLU (P<0.05). After IN, relative to GLU, the changes in SCFA-AUC 4-6 were negatively related to the changes in ghrelin-AUC 4-6 (P=0.017). SCFA and hormone responses did not differ significantly between LN and OWO. Acute increases in colonic SCFA do not affect GLP-1 or PYY responses in LN or OWO subjects, but may reduce ghrelin. The results do not support the hypothesis that SCFA acutely stimulate PYY and GLP-1 secretion; however, a longer adaptation to increased colonic fermentation or a larger sample size may yield different results.

  6. Novel kinin B1 receptor agonists with improved pharmacological profiles.

    PubMed

    Côté, Jérôme; Savard, Martin; Bovenzi, Veronica; Bélanger, Simon; Morin, Josée; Neugebauer, Witold; Larouche, Annie; Dubuc, Céléna; Gobeil, Fernand

    2009-04-01

    There is some evidence to suggest that inducible kinin B1 receptors (B1R) may play beneficial and protecting roles in cardiovascular-related pathologies such as hypertension, diabetes, and ischemic organ diseases. Peptide B1R agonists bearing optimized pharmacological features (high potency, selectivity and stability toward proteolysis) hold promise as valuable therapeutic agents in the treatment of these diseases. In the present study, we used solid-phase methodology to synthesize a series of novel peptide analogues based on the sequence of Sar[dPhe(8)]desArg(9)-bradykinin, a relatively stable peptide agonist with moderate affinity for the human B1R. We evaluated the pharmacological properties of these peptides using (1) in vitro competitive binding experiments on recombinant human B1R and B2R (for index of selectivity determination) in transiently transfected human embryonic kidney 293 cells (HEK-293T cells), (2) ex vivo vasomotor assays on isolated human umbilical veins expressing endogenous human B1R, and (3) in vivo blood pressure tests using anesthetized lipopolysaccharide-immunostimulated rabbits. Key chemical modifications at the N-terminus, the positions 3 and 5 on Sar[dPhe(8)]desArg(9)-bradykinin led to potent analogues. For example, peptides 18 (SarLys[Hyp(3),Cha(5), dPhe(8)]desArg(9)-bradykinin) and 20 (SarLys[Hyp(3),Igl(5), dPhe(8)]desArg(9)-bradykinin) outperformed the parental molecule in terms of affinity, functional potency and duration of action in vitro and in vivo. These selective agonists should be valuable in future animal and human studies to investigate the potential benefits of B1R activation.

  7. Platelet Kinetics in Idiopathic Thrombocytopenic Purpura Patients Treated with Thrombopoietin Receptor Agonists

    PubMed Central

    Meyer, Oliver; Herzig, Eric; Salama, Abdulgabar

    2012-01-01

    Aim Thrombopoietin receptor agonists (Tpo RA) increase platelet counts in the majority of chronic autoimmune thrombocytopenia (idiopathic thrombocytopenic purpura; ITP) patients. It is unknown whether this treatment may also improve platelet survival (PS) in these patients. Methods In order to determine platelet survival (PS), autologous platelets were labeled with 111In oxine and retransfused in six patients under treatment with Tpo RA (romiplostim n = 3; eltrombopag n = 3). Results Stable platelet counts of greater than 100 × 103/μl were observed in all 6 patients. Platelet survival was decreased in all cases (mean 2.10 days; range 0.13–3.73 days). No correlation was found between platelet count and PS. Similarly, there was no significant relationship between platelet turnover and platelet count. However, a high platelet turnover, exceeding 25 or three times the norm was observed in 2 patients who presented the lowest PS (0.13 or 0.83 days). Two patients had a moderately shortened PS (1.91 or 2.42 days), and, correspondingly, a moderately increased platelet turnover rate (63,072 or 72,872 platelets/μl/day). Conclusion These results indicate that Tpo RA may not only overcompensate platelet destruction in ITP, but may interfere with other mechanisms, which, in some cases, results in a reduced platelet destruction rate. PMID:22896760

  8. Impaired β-arrestin recruitment and reduced desensitization by non-catechol agonists of the D1 dopamine receptor.

    PubMed

    Gray, David L; Allen, John A; Mente, Scot; O'Connor, Rebecca E; DeMarco, George J; Efremov, Ivan; Tierney, Patrick; Volfson, Dmitri; Davoren, Jennifer; Guilmette, Edward; Salafia, Michelle; Kozak, Rouba; Ehlers, Michael D

    2018-02-14

    Selective activation of dopamine D1 receptors (D1Rs) has been pursued for 40 years as a therapeutic strategy for neurologic and psychiatric diseases due to the fundamental role of D1Rs in motor function, reward processing, and cognition. All known D1R-selective agonists are catechols, which are rapidly metabolized and desensitize the D1R after prolonged exposure, reducing agonist response. As such, drug-like selective D1R agonists have remained elusive. Here we report a novel series of selective, potent non-catechol D1R agonists with promising in vivo pharmacokinetic properties. These ligands stimulate adenylyl cyclase signaling and are efficacious in a rodent model of Parkinson's disease after oral administration. They exhibit distinct binding to the D1R orthosteric site and a novel functional profile including minimal receptor desensitization, reduced recruitment of β-arrestin, and sustained in vivo efficacy. These results reveal a novel class of D1 agonists with favorable drug-like properties, and define the molecular basis for catechol-specific recruitment of β-arrestin to D1Rs.

  9. Effect of the glucagon-like peptide-1 receptor agonist lixisenatide on postprandial hepatic glucose metabolism in the conscious dog.

    PubMed

    Moore, Mary Courtney; Werner, Ulrich; Smith, Marta S; Farmer, Tiffany D; Cherrington, Alan D

    2013-12-01

    The impact of the GLP-1 receptor agonist lixisenatide on postprandial glucose disposition was examined in conscious dogs to identify mechanisms for its improvement of meal tolerance in humans and examine the tissue disposition of meal-derived carbohydrate. Catheterization for measurement of hepatic balance occurred ≈16 days before study. After being fasted overnight, dogs received a subcutaneous injection of 1.5 μg/kg lixisenatide or vehicle (saline, control; n = 6/group). Thirty minutes later, they received an oral meal feeding (93.4 kJ; 19% protein, 71% glucose polymers, and 10% lipid). Acetaminophen was included in the meal in four control and five lixisenatide dogs for assessment of gastric emptying. Observations continued for 510 min; absorption was incomplete in lixisenatide at that point. The plasma acetaminophen area under the curve (AUC) in lixisenatide was 65% of that in control (P < 0.05). Absorption of the meal began within 15 min in control but was delayed until ≈30-45 min in lixisenatide. Lixisenatide reduced (P < 0.05) the postprandial arterial glucose AUC ≈54% and insulin AUC ≈44%. Net hepatic glucose uptake did not differ significantly between groups. Nonhepatic glucose uptake tended to be reduced by lixisenatide (6,151 ± 4,321 and 10,541 ± 1,854 μmol·kg(-1)·510 min(-1) in lixisenatide and control, respectively; P = 0.09), but adjusted (for glucose and insulin concentrations) values did not differ (18.9 ± 3.8 and 19.6 ± 7.9 l·kg(-1)·pmol(-1)·l(-1), lixisenatide and control, respectively; P = 0.94). Thus, lixisenatide delays gastric emptying, allowing more efficient disposal of the carbohydrate in the feeding without increasing liver glucose disposal. Lixisenatide could prove to be a valuable adjunct in treatment of postprandial hyperglycemia in impaired glucose tolerance or type 2 diabetes.

  10. Effect of the glucagon-like peptide-1 receptor agonist lixisenatide on postprandial hepatic glucose metabolism in the conscious dog

    PubMed Central

    Werner, Ulrich; Smith, Marta S.; Farmer, Tiffany D.; Cherrington, Alan D.

    2013-01-01

    The impact of the GLP-1 receptor agonist lixisenatide on postprandial glucose disposition was examined in conscious dogs to identify mechanisms for its improvement of meal tolerance in humans and examine the tissue disposition of meal-derived carbohydrate. Catheterization for measurement of hepatic balance occurred ≈16 days before study. After being fasted overnight, dogs received a subcutaneous injection of 1.5 μg/kg lixisenatide or vehicle (saline, control; n = 6/group). Thirty minutes later, they received an oral meal feeding (93.4 kJ; 19% protein, 71% glucose polymers, and 10% lipid). Acetaminophen was included in the meal in four control and five lixisenatide dogs for assessment of gastric emptying. Observations continued for 510 min; absorption was incomplete in lixisenatide at that point. The plasma acetaminophen area under the curve (AUC) in lixisenatide was 65% of that in control (P < 0.05). Absorption of the meal began within 15 min in control but was delayed until ≈30–45 min in lixisenatide. Lixisenatide reduced (P < 0.05) the postprandial arterial glucose AUC ≈54% and insulin AUC ≈44%. Net hepatic glucose uptake did not differ significantly between groups. Nonhepatic glucose uptake tended to be reduced by lixisenatide (6,151 ± 4,321 and 10,541 ± 1,854 μmol·kg−1·510 min−1 in lixisenatide and control, respectively; P = 0.09), but adjusted (for glucose and insulin concentrations) values did not differ (18.9 ± 3.8 and 19.6 ± 7.9 l·kg−1·pmol−1·l−1, lixisenatide and control, respectively; P = 0.94). Thus, lixisenatide delays gastric emptying, allowing more efficient disposal of the carbohydrate in the feeding without increasing liver glucose disposal. Lixisenatide could prove to be a valuable adjunct in treatment of postprandial hyperglycemia in impaired glucose tolerance or type 2 diabetes. PMID:24148347

  11. Cardiovascular Biology of the Incretin System

    PubMed Central

    Ussher, John R.; Drucker, Daniel J.

    2012-01-01

    Glucagon-like peptide-1 (GLP-1) is an incretin hormone that enhances glucose-stimulated insulin secretion and exerts direct and indirect actions on the cardiovascular system. GLP-1 and its related incretin hormone, glucose-dependent insulinotropic polypeptide (GIP), are rapidly inactivated by the enzyme dipeptidyl peptidase 4 (DPP-4), a key determinant of incretin bioactivity. Two classes of medications that enhance incretin action, GLP-1R agonists and DPP-4 inhibitors, are used for the treatment of type 2 diabetes mellitus (T2DM). We review herein the cardiovascular biology of GLP-1R agonists and DPP-4 inhibitors, including direct and indirect effects on cardiomyocytes, blood vessels, adipocytes, the control of blood pressure and postprandial lipoprotein secretion. Both GLP-1R activation and DPP-4 inhibition exert multiple cardioprotective actions in preclinical models of cardiovascular dysfunction, and short term studies in human subjects appear to demonstrate modest yet beneficial actions on cardiac function in subjects with ischemic heart disease. Incretin-based agents control body weight, improve glycemic control with a low risk of hypoglycemia, decrease blood pressure, inhibit the secretion of intestinal chylomicrons, and reduce inflammation in preclinical studies. Nevertheless, there is limited information on the cardiovascular actions of these agents in patients with diabetes and established cardiovascular disease. Hence, a more complete understanding of the cardiovascular risk:benefit ratio of incretin-based therapies will require completion of long term cardiovascular outcome studies currently underway in patients with T2DM. PMID:22323472

  12. Proglucagon-Derived Peptides Do Not Significantly Affect Acute Exocrine Pancreas in Rats

    PubMed Central

    Akalestou, Elina; Christakis, Ioannis; Solomou, Antonia M.; Minnion, James S.; Rutter, Guy A.; Bloom, Stephen R.

    2015-01-01

    Objectives Reports have suggested a link between treatment with glucagon-like peptide 1 (GLP-1) analogues and an increased risk of pancreatitis. Oxyntomodulin, a dual agonist of both GLP-1 and glucagon receptors, is currently being investigated as a potential anti-obesity therapy, but little is known about its pancreatic safety. The aim of this study was to investigate the acute effect of oxyntomodulin and other proglucagon-derived peptides on the rat exocrine pancreas. Methods GLP-1, oxyntomodulin, glucagon and exendin-4 were infused into anaesthetised rats to measure plasma amylase concentration changes. Additionally, the effect of each peptide on both amylase release and proliferation in rat pancreatic acinar (AR42J) and primary isolated ductal cells was determined. Results Plasma amylase did not increase post peptide infusion, compared to vehicle and cholecystokinin (CCK); however, oxyntomodulin inhibited plasma amylase when co-administered with CCK. None of the peptides caused a significant increase in proliferation rate or amylase secretion from acinar and ductal cells. Conclusions The investigated peptides do not have an acute effect on the exocrine pancreas with regard to proliferation and plasma amylase, when administered individually. Oxyntomodulin appears to be a potent inhibitor of amylase release, potentially making it a safer anti-obesity agent regarding pancreatitis, compared to GLP-1 agonists. PMID:26731187

  13. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Onuma, Hirohisa; Inukai, Kouichi, E-mail: kinukai@ks.kyorin-u.ac.jp; Kitahara, Atsuko

    Highlights: • PPARγ activation was involved in the GLP-1-mediated anti-inflammatory action. • Exendin-4 enhanced endogenous PPARγ transcriptional activity in HUVECs. • H89, a PKA inhibitor, abolished GLP-1-induced PPARγ enhancement. • The anti-inflammatory effects of GLP-1 may be explained by PPARγ activation. - Abstract: Recent studies have suggested glucagon-like peptide-1 (GLP-1) signaling to exert anti-inflammatory effects on endothelial cells, although the precise underlying mechanism remains to be elucidated. In the present study, we investigated whether PPARγ activation is involved in the GLP-1-mediated anti-inflammatory action on endothelial cells. When we treated HUVEC cells with 0.2 ng/ml exendin-4, a GLP-1 receptor agonist, endogenousmore » PPARγ transcriptional activity was significantly elevated, by approximately 20%, as compared with control cells. The maximum PPARγ activity enhancing effect of exendin-4 was observed 12 h after the initiation of incubation with exendin-4. As H89, a PKA inhibitor, abolished GLP-1-induced PPARγ enhancement, the signaling downstream from GLP-1 cross-talk must have been involved in PPARγ activation. In conclusion, our results suggest that GLP-1 has the potential to induce PPARγ activity, partially explaining the anti-inflammatory effects of GLP-1 on endothelial cells. Cross-talk between GLP-1 signaling and PPARγ activation would have major impacts on treatments for patients at high risk for cardiovascular disease.« less

  14. Quest for harmonisation: differences and similarities in national programmes for GLP monitoring. A senior inspector's viewpoint.

    PubMed

    Helder, Theo

    2008-01-01

    The conditions under which safety data may be accepted by regulatory authorities (RAs) in OECD Countries do not only include the obligation to apply the principles of good laboratory practice (GLP) while producing these data, but also must countries, partaking in the Organisation for Economic Cooperation and Development (OECD) system for mutual acceptance of data (MAD), establish a monitoring programme to ensure proper application of the GLP principles. Detailed guidance to this end is given in the OECD GLP documents No. 2 and 3. Nevertheless, this guidance permits countries quite some freedom where it concerns the organisation of their programmes. Monitoring programmes may be embedded in governmental as well as private structures. It appears that GLP compliance monitoring is increasingly charged to accreditation bodies. Inspectors may be full-time or part-time workers, and there are differences in scheduling and performing inspections and study audits. Also the financing of the monitoring programmes is diverging: in some countries the programme is fully or partly paid by the inspected test facilities (TFs), while in other countries the financing comes from the national treasury. Is there a need for harmonisation in this area, as there is and was in the interpretation of the GLP principles themselves? Over the years more than ten consensus and advisory documents have been published by the OECD working group on GLP. The very existence of these documents is however no guarantee that the interpretation of the GLP principles by inspectors is similar, let alone identical. The most important criterion is, in fact, that there be no harm for human health and the environment.

  15. Impact of Sleeve Gastrectomy on Type 2 Diabetes Mellitus, Gastric Emptying Time, Glucagon-Like Peptide 1 (GLP-1), Ghrelin and Leptin in Non-morbidly Obese Subjects with BMI 30-35.0 kg/m2: a Prospective Study.

    PubMed

    Vigneshwaran, B; Wahal, Akshat; Aggarwal, Sandeep; Priyadarshini, Pratyusha; Bhattacharjee, Hemanga; Khadgawat, Rajesh; Yadav, Rajkumar

    2016-12-01

    The study was conducted to evaluate the impact of laparoscopic sleeve gastrectomy (LSG) on type 2 diabetes mellitus (T2DM) in patients with a body mass index (BMI) of 30.0-35.0 kg/m 2 . Possible mechanisms, including alterations in gastric emptying time (GET), glucagon-like peptide 1 (GLP-1), ghrelin and leptin, were evaluated. Twenty obese patients with T2DM and with a BMI of 30.0-35.0 kg/m 2 underwent LSG during March 2012 to February 2015. Glycosylated haemoglobin (HbA1c), fasting plasma glucose (FPG) and GET were measured at baseline, 3 months, 6 months, 12 months and 24 months after surgery. Fasting and post-prandial levels of serum GLP-1, ghrelin and leptin were measured pre-operatively and after 3 and 6 months. The average duration of follow-up was 17.6 months, and 10 patients had completed 2 years of follow-up. After 2 years, the average BMI decreased from 33.4 ± 1.2 to 26.7 ± 1.8 kg/m 2 . The mean HbA1c decreased from 8.7 ± 1.6 to 6.7 ± 1.5 %, respectively. Ten patients achieved complete remission. Insulin could be stopped in all six patients who were on it pre-operatively. Meal-stimulated GLP-1 response and serum insulin at 30 min showed a significant increase following surgery. There was a significant decrease in GET. This prospective study confirms the positive impact of LSG on diabetic status of non-morbidly obese patients. The possible mechanisms include the rise in post-prandial GLP-1 level induced by accelerated gastric emptying, leading to an increase in insulin secretion. LSG also leads to decreased ghrelin and leptin levels which may have a role in improving glucose homeostasis after surgery.

  16. AMP is an adenosine A1 receptor agonist.

    PubMed

    Rittiner, Joseph E; Korboukh, Ilia; Hull-Ryde, Emily A; Jin, Jian; Janzen, William P; Frye, Stephen V; Zylka, Mark J

    2012-02-17

    Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5'-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5'-monophosphonate, ACP) directly activated the adenosine A(1) receptor (A(1)R). In contrast, AMP only activated the adenosine A(2B) receptor (A(2B)R) after hydrolysis to adenosine by ecto-5'-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A(1)R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A(1)R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A(1)R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A(1)R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine.

  17. The non-biphenyl-tetrazole angiotensin AT1 receptor antagonist eprosartan is a unique and robust inverse agonist of the active state of the AT1 receptor.

    PubMed

    Takezako, Takanobu; Unal, Hamiyet; Karnik, Sadashiva S; Node, Koichi

    2018-03-23

    Conditions such as hypertension and renal allograft rejection are accompanied by chronic, agonist-independent, signalling by angiotensin II AT 1 receptors. The current treatment paradigm for these diseases entails the preferred use of inverse agonist AT 1 receptor blockers (ARBs). However, variability in the inverse agonist activities of common biphenyl-tetrazole ARBs for the active state of AT 1 receptors often leads to treatment failure. Therefore, characterization of robust inverse agonist ARBs for the active state of AT 1 receptors is necessary. To identify the robust inverse agonist for active state of AT 1 receptors and its molecular mechanism, we performed site-directed mutagenesis, competition binding assay, inositol phosphate production assay and molecular modelling for both ground-state wild-type AT 1 receptors and active-state N111G mutant AT 1 receptors. Although candesartan and telmisartan exhibited weaker inverse agonist activity for N111G- compared with WT-AT 1 receptors, only eprosartan exhibited robust inverse agonist activity for both N111G- and WT- AT 1 receptors. Specific ligand-receptor contacts for candesartan and telmisartan are altered in the active-state N111G- AT 1 receptors compared with the ground-state WT-AT 1 receptors, suggesting an explanation of their attenuated inverse agonist activity for the active state of AT 1 receptors. In contrast, interactions between eprosartan and N111G-AT 1 receptors were not significantly altered, and the inverse agonist activity of eprosartan was robust. Eprosartan may be a better therapeutic option than other ARBs. Comparative studies investigating eprosartan and other ARBs for the treatment of diseases caused by chronic, agonist-independent, AT 1 receptor activation are warranted. © 2018 The British Pharmacological Society.

  18. A Sphingosine 1-phosphate receptor 2 selective allosteric agonist

    PubMed Central

    Satsu, Hideo; Schaeffer, Marie-Therese; Guerrero, Miguel; Saldana, Adrian; Eberhart, Christina; Hodder, Peter; Cayanan, Charmagne; Schürer, Stephan; Bhhatarai, Barun; Roberts, Ed; Rosen, Hugh; Brown, Steven J.

    2013-01-01

    Molecular probe tool compounds for the Sphingosine 1-phosphate receptor 2 (S1PR2) are important for investigating the multiple biological processes in which the S1PR2 receptor has been implicated. Amongst these are NF-κB-mediated tumor cell survival and fibroblast chemotaxis to fibronectin. Here we report our efforts to identify selective chemical probes for S1PR2 and their characterization. We employed high throughput screening to identify two compounds which activate the S1PR2 receptor. SAR optimization led to compounds with high nanomolar potency. These compounds, XAX-162 and CYM-5520, are highly selective and do not activate other S1P receptors. Binding of CYM-5520 is not competitive with the antagonist JTE-013. Mutation of receptor residues responsible for binding to the zwitterionic headgroup of sphingosine 1-phosphate (S1P) abolishes S1P activation of the receptor, but not activation by CYM-5520. Competitive binding experiments with radiolabeled S1P demonstrate that CYM-5520 is an allosteric agonist and does not displace the native ligand. Computational modeling suggests that CYM-5520 binds lower in the orthosteric binding pocket, and that co-binding with S1P is energetically well tolerated. In summary, we have identified an allosteric S1PR2 selective agonist compound. PMID:23849205

  19. Beneficial effect of lixisenatide after 76 weeks of treatment in patients with type 2 diabetes mellitus: A meta-analysis from the GetGoal programme.

    PubMed

    Broglio, Fabio; Mannucci, Edoardo; Napoli, Raffaele; Nicolucci, Antonio; Purrello, Francesco; Nikonova, Elena; Stager, William; Trevisan, Roberto

    2017-02-01

    To evaluate the long-term efficacy and safety of lixisenatide, a short-acting, prandial glucagon-like peptide-1 receptor agonists (GLP-1 RA) as add-on therapy in type 2 diabetes mellitus. A meta-analysis of 76-week results of 5 placebo-controlled clinical trials from the GetGoal programme was performed, including 3000 inadequately controlled adult diabetic patients where lixisenatide 20 µg once-daily was administered in combination with metformin (GetGoal-M and GetGoal-F1), sulphonylurea ± metformin (GetGoal-S), basal insulin ± metformin (GetGoal-L) or pioglitazone ± metformin (GetGoal-P). A significant reduction in HbA1c at 76 weeks was observed in the intervention arm compared to placebo (LSM difference: -0.41%, 95%CI: -0.51, -0.32, P < .00001). Compared to placebo, lixisenatide induced a larger decrease in fasting plasma glucose (LSM difference -0.49 mmol/L, 95% CI -0.71, -0.27, P < .0001) and postprandial glucose excursion after a standard test meal (LSM difference -3.29 mmol/L, 95% CI -4.17, -2.42, P < .00001). A bodyweight reduction was observed in the lixisenatide arm (LSM difference -0.40 kg, 95%CI: -0.8, -0.01, P = .05). The risk of hypoglycaemia was slightly higher with lixisenatide vs placebo (risk difference +0.02, 95% CI: 0, 0.04, P = .04). The most commonly observed non-severe adverse events were nausea and vomiting, which after week 16 and week 8, were steadily <4% and <1% in the lixisenatide arm, respectively. Lixisenatide, a once-daily prandial GLP-1 RA, provides long-term glycaemic control, a sustained beneficial effect on weight and with a good safety profile. © 2016 John Wiley & Sons Ltd.

  20. The Fas/Fap-1/Cav-1 complex regulates IL-1RA secretion in mesenchymal stem cells to accelerate wound healing.

    PubMed

    Kou, Xiaoxing; Xu, Xingtian; Chen, Chider; Sanmillan, Maria Laura; Cai, Tao; Zhou, Yanheng; Giraudo, Claudio; Le, Anh; Shi, Songtao

    2018-03-14

    Mesenchymal stem cells (MSCs) are capable of secreting exosomes, extracellular vesicles, and cytokines to regulate cell and tissue homeostasis. However, it is unknown whether MSCs use a specific exocytotic fusion mechanism to secrete exosomes and cytokines. We show that Fas binds with Fas-associated phosphatase-1 (Fap-1) and caveolin-1 (Cav-1) to activate a common soluble N -ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE)-mediated membrane fusion mechanism to release small extracellular vesicles (sEVs) in MSCs. Moreover, we reveal that MSCs produce and secrete interleukin-1 receptor antagonist (IL-1RA) associated with sEVs to maintain rapid wound healing in the gingiva via the Fas/Fap-1/Cav-1 cascade. Tumor necrosis factor-α (TNF-α) serves as an activator to up-regulate Fas and Fap-1 expression via the nuclear factor κB pathway to promote IL-1RA release. This study identifies a previously unknown Fas/Fap-1/Cav-1 axis that regulates SNARE-mediated sEV and IL-1RA secretion in stem cells, which contributes to accelerated wound healing. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  1. Efficacy and Safety of the Once-Daily GLP-1 Receptor Agonist Lixisenatide in Monotherapy

    PubMed Central

    Fonseca, Vivian A.; Alvarado-Ruiz, Ricardo; Raccah, Denis; Boka, Gabor; Miossec, Patrick; Gerich, John E.

    2012-01-01

    OBJECTIVE To assess efficacy and safety of lixisenatide monotherapy in type 2 diabetes. RESEARCH DESIGN AND METHODS Randomized, double-blind, 12-week study of 361 patients not on glucose-lowering therapy (HbA1c 7–10%) allocated to one of four once-daily subcutaneous dose increase regimens: lixisenatide 2-step (10 μg for 1 week, 15 μg for 1 week, and then 20 μg; n = 120), lixisenatide 1-step (10 μg for 2 weeks and then 20 μg; n = 119), placebo 2-step (n = 61), or placebo 1-step (n = 61) (placebo groups were combined for analyses). Primary end point was HbA1c change from baseline to week 12. RESULTS Once-daily lixisenatide significantly improved HbA1c (mean baseline 8.0%) in both groups (least squares mean change vs. placebo: −0.54% for 2-step, −0.66% for 1-step; P < 0.0001). Significantly more lixisenatide patients achieved HbA1c <7.0% (52.2% 2-step, 46.5% 1-step) and ≤6.5% (31.9% 2-step, 25.4% 1-step) versus placebo (26.8% and 12.5%, respectively; P < 0.01). Lixisenatide led to marked significant improvements of 2-h postprandial glucose levels and blood glucose excursions measured during a standardized breakfast test. A significant decrease in fasting plasma glucose was observed in both lixisenatide groups versus placebo. Mean decreases in body weight (∼2 kg) were observed in all groups. The most common adverse events were gastrointestinal—nausea was the most frequent (lixisenatide 23% overall, placebo 4.1%). Symptomatic hypoglycemia occurred in 1.7% of lixisenatide and 1.6% of placebo patients, with no severe episodes. Safety/tolerability was similar for the two dose regimens. CONCLUSIONS Once-daily lixisenatide monotherapy significantly improved glycemic control with a pronounced postprandial effect (75% reduction in glucose excursion) and was safe and well tolerated in type 2 diabetes. PMID:22432104

  2. Fasting Induces IL-1 Resistance and Free-Fatty Acid-Mediated Up-Regulation of IL-1R2 and IL-1RA

    PubMed Central

    Joesting, Jennifer J.; Moon, Morgan L.; Gainey, Stephen J.; Tisza, Brittany L.; Blevins, Neil A.; Freund, Gregory G.

    2014-01-01

    Objective: Weight-loss is a near societal obsession and many diet programs use significant calorie restriction including fasting/short term starvation to generate rapid effects. Fasting is also a well-recognized cause of immunosuppression especially within the innate immune system. In this study, we sought to determine if the IL-1 arm of the neuroimmune system was down-regulated by a 24 h fast and how fasting might generate this effect. Design: Mice were allowed ad libitum access to food or had food withheld for 24 h. Expression of the endogenous IL-1 antagonists, IL-1 receptor type 2 (IL-1R2), and IL-1 receptor antagonist (IL-1RA) was determined as were sickness behaviors before and after IL-1β administration. Results: Fasting markedly increased gene expression of IL-1R2 (83-fold in adipose tissue, 9.5-fold in liver) and IL-1RA (68-fold in liver). Fasted mice were protected from IL-1β-induced weight-loss, hypoglycemia, loss of locomotor, and social anxiety. These protections were coupled to a large positive interaction of fasting and IL-1β on IL-1R2 gene expression in adipose tissue and liver (2.6- and 1.6-fold, respectively). Fasting not only increased IL-1RA and IL-1R2 protein 2.5- and 3.2-fold, respectively, in liver but also increased IL-1R2 1.8-fold in adipose tissue. Fasting, in turn, triggered a 2.4-fold increase in plasma free-fatty acids (FFAs) and a 2.1-fold increase in plasma corticosterone. Inhibition, of glucocorticoid action with mifepristone did not impact fasting-dependent IL-1R2 or IL-1RA gene expression. Administration of the FFA, palmitate, to mice increased liver IL-1R2 and IL-1RA gene expression by 14- and 11-fold, respectively. Conclusion: These findings indicate that fasting augments expression of endogenous IL-1 antagonists inducing IL-1 resistance. Fasting-induced increases in plasma FFAs appears to be a signal that drives immunosuppression during fasting/short term starvation. PMID:25071776

  3. G9a/GLP histone lysine dimethyltransferase complex activity in the hippocampus and the entorhinal cortex is required for gene activation and silencing during memory consolidation.

    PubMed

    Gupta-Agarwal, Swati; Franklin, Aimee V; Deramus, Thomas; Wheelock, Muriah; Davis, Robin L; McMahon, Lori L; Lubin, Farah D

    2012-04-18

    Learning triggers alterations in gene transcription in brain regions such as the hippocampus and the entorhinal cortex (EC) that are necessary for long-term memory (LTM) formation. Here, we identify an essential role for the G9a/G9a-like protein (GLP) lysine dimethyltransferase complex and the histone H3 lysine 9 dimethylation (H3K9me2) marks it catalyzes, in the transcriptional regulation of genes in area CA1 of the rat hippocampus and the EC during memory consolidation. Contextual fear learning increased global levels of H3K9me2 in area CA1 and the EC, with observable changes at the Zif268, DNMT3a, BDNF exon IV, and cFOS gene promoters, which occurred in concert with mRNA expression. Inhibition of G9a/GLP in the EC, but not in the hippocampus, enhanced contextual fear conditioning relative to control animals. The inhibition of G9a/GLP in the EC induced several histone modifications that include not only methylation but also acetylation. Surprisingly, we found that downregulation of G9a/GLP activity in the EC enhanced H3K9me2 in area CA1, resulting in transcriptional silencing of the non-memory permissive gene COMT in the hippocampus. In addition, synaptic plasticity studies at two distinct EC-CA1 cellular pathways revealed that G9a/GLP activity is critical for hippocampus-dependent long-term potentiation initiated in the EC via the perforant pathway, but not the temporoammonic pathway. Together, these data demonstrate that G9a/GLP differentially regulates gene transcription in the hippocampus and the EC during memory consolidation. Furthermore, these findings support the possibility of a role for G9a/GLP in the regulation of cellular and molecular cross talk between these two brain regions during LTM formation.

  4. Deacetylmycoepoxydiene is an agonist of Rac1, and simultaneously induces autophagy and apoptosis.

    PubMed

    Xie, Wei; Zhang, Wei; Sun, Mingwei; Lu, Chunhua; Shen, Yuemao

    2018-05-09

    Lung cancer is the second most common cause of cancer-related death in the world. Most cases of lung cancer are not curable, especially non-small cell lung cancer (NSCLC). Thus, novel treatment targets for this malignant disease are urgently needed. Here, we demonstrate the feasibility of Rac1 in treating p53-null human NSCLC H1299 as a novel drug target. Deacetylmycoepoxydiene (DA-MED), a cytotoxic natural polyketide, functions as a Rac1 agonist in p53-null NSCLC H1299 cells. DA-MED treatment drives Rac1 activation and promotes robust production of reactive oxygen species, activating mitochondrial permeability transition and the intrinsic apoptotic pathway. Knockdown of Rac1 decreases ROS production in DA-MED-treated cells, resulting in a concomitant decrease in DA-MED-induced apoptosis. DA-MED-activated Rac1 induces autophagy by inhibiting mammalian target of rapamycin, leading to anti-apoptotic and anti-metastatic effects. Therefore, this study provides novel insight into the complex cytotoxic and pro-survival mechanisms associated with a potent Rac1 agonist and suggests that further development of more potent Rac1 agonists could be an effective strategy for future non-small cell lung cancer treatments.

  5. Short-chain fatty acid sensing in rat duodenum

    PubMed Central

    Akiba, Yasutada; Inoue, Takuya; Kaji, Izumi; Higashiyama, Masaaki; Narimatsu, Kazuyuki; Iwamoto, Ken-ichi; Watanabe, Masahiko; Guth, Paul H; Engel, Eli; Kuwahara, Atsukazu; Kaunitz, Jonathan D

    2015-01-01

    Intraduodenal fatty acids (FA) and bacterial overgrowth, which generate short-chain FAs (SCFAs), have been implicated in the generation of functional dyspepsia symptoms. We studied the mechanisms by which luminal SCFA perfusion affects duodenal HCO3− secretion (DBS), a measure of mucosal neurohumoral activation. Free fatty acid receptor (FFAR) 1 (FFA1), which binds long-chain FA (LCFA), and SCFA receptors FFA2 and FFA3 were immunolocalised to duodenal enteroendocrine cells. FFA3 colocalised with glucagon-like peptide (GLP)-1, whereas FFA2 colocalised with 5-HT. Luminal perfusion of the SCFA acetate or propionate increased DBS, enhanced by dipeptidyl peptidase-IV (DPPIV) inhibition, at the same time as increasing GLP-2 portal blood concentrations. Acetate-induced DBS was partially inhibited by monocarboxylate/HCO3− exchanger inhibition without affecting GLP-2 release, implicating acetate absorption in the partial mediation of DBS. A selective FFA2 agonist dose-dependently increased DBS, unaffected by DPPIV inhibition or by cholecystokinin or 5-HT3 receptor antagonists, but was inhibited by atropine and a 5-HT4 antagonist. By contrast, a selective FFA1 agonist increased DBS accompanied by GLP-2 release, enhanced by DPPIV inhibition and inhibited by a GLP-2 receptor antagonist. Activation of FFA1 by LCFA and presumably FFA3 by SCFA increased DBS via GLP-2 release, whereas FFA2 activation stimulated DBS via muscarinic and 5-HT4 receptor activation. SCFA/HCO3− exchange also appears to be present in the duodenum. The presence of duodenal fatty acid sensing receptors that signal hormone release and possibly signal neural activation may be implicated in the pathogenesis of functional dyspepsia. PMID:25433076

  6. Vascular Biology of Glucagon Receptor Superfamily Peptides: Mechanistic and Clinical Relevance.

    PubMed

    Pujadas, Gemma; Drucker, Daniel J

    2016-12-01

    Regulatory peptides produced in islet and gut endocrine cells, including glucagon, glucagon-like peptide-1 (GLP-1), GLP-2, and glucose-dependent insulinotropic polypeptide, exert actions with considerable metabolic importance and translational relevance. Although the clinical development of GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors has fostered research into how these hormones act on the normal and diseased heart, less is known about the actions of these peptides on blood vessels. Here we review the effects of these peptide hormones on normal blood vessels and highlight their vascular actions in the setting of experimental and clinical vascular injury. The cellular localization and signal transduction properties of the receptors for glucagon, GLP-1, GLP-2, and glucose-dependent insulinotropic polypeptide are discussed, with emphasis on endothelial cells and vascular smooth muscle cells. The actions of these peptides on the control of blood flow, blood pressure, angiogenesis, atherosclerosis, and vascular inflammation are reviewed with a focus on elucidating direct and indirect mechanisms of action. How these peptides traverse the blood-brain barrier is highlighted, with relevance to the use of GLP-1 receptor agonists to treat obesity and neurodegenerative disorders. Wherever possible, we compare actions identified in cell lines and primary cell culture with data from preclinical studies and, when available, results of human investigation, including studies in subjects with diabetes, obesity, and cardiovascular disease. Throughout the review, we discuss pitfalls, limitations, and challenges of the existing literature and highlight areas of controversy and uncertainty. The increasing use of peptide-based therapies for the treatment of diabetes and obesity underscores the importance of understanding the vascular biology of peptide hormone action.

  7. Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors.

    PubMed

    Koshimizu, Taka-Aki; Kashiwazaki, Aki; Taniguchi, Junichi

    2016-05-03

    Reducing Na(+) in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na(+)-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na(+) sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na(+) increased cell surface [(3)H]AVP binding and decreased receptor internalization. Substitution of Na(+) by Cs(+) or NH4(+) inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na(+) over Cs(+). Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations.

  8. Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors

    PubMed Central

    Koshimizu, Taka-aki; Kashiwazaki, Aki; Taniguchi, Junichi

    2016-01-01

    Reducing Na+ in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na+-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na+ sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na+ increased cell surface [3H]AVP binding and decreased receptor internalization. Substitution of Na+ by Cs+ or NH4+ inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na+ over Cs+. Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations. PMID:27138239

  9. The Roles of IL-6, IL-10, and IL-1RA in Obesity and Insulin Resistance in African-Americans

    PubMed Central

    Doumatey, Ayo; Huang, Hanxia; Zhou, Jie; Chen, Guanjie; Shriner, Daniel; Adeyemo, Adebowale

    2011-01-01

    Objective: The aim of the study was to investigate the associations between IL-1 receptor antagonist (IL-1RA), IL-6, IL-10, measures of obesity, and insulin resistance in African-Americans. Research Design and Methods: Nondiabetic participants (n = 1025) of the Howard University Family Study were investigated for associations between serum IL (IL-1RA, IL-6, IL-10), measures of obesity, and insulin resistance, with adjustment for age and sex. Measures of obesity included body mass index, waist circumference, hip circumference, waist-to-hip ratio, and percent fat mass. Insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA-IR). Data were analyzed with R statistical software using linear regression and likelihood ratio tests. Results: IL-1RA and IL-6 were associated with measures of obesity and insulin resistance, explaining 4–12.7% of the variance observed (P values < 0.001). IL-1RA was bimodally distributed and therefore was analyzed based on grouping those with low vs. high IL-1RA levels. High IL-1RA explained up to 20 and 12% of the variance in measures of obesity and HOMA-IR, respectively. Among the IL, only high IL-1RA improved the fit of models regressing HOMA-IR on measures of obesity. In contrast, all measures of obesity improved the fit of models regressing HOMA-IR on IL. IL-10 was not associated with obesity measures or HOMA-IR. Conclusions: High IL-1RA levels and obesity measures are associated with HOMA-IR in this population-based sample of African-Americans. The results suggest that obesity and increased levels of IL-1RA both contribute to the development of insulin resistance. PMID:21956416

  10. Radioiodinated Exendin-4 Is Superior to the Radiometal-Labelled Glucagon-Like Peptide-1 Receptor Probes Overcoming Their High Kidney Uptake

    PubMed Central

    Läppchen, Tilman; Tönnesmann, Roswitha; Eersels, Jos; Meyer, Philipp T.; Maecke, Helmut R.; Rylova, Svetlana N.

    2017-01-01

    GLP-1 receptors are ideal targets for preoperative imaging of benign insulinoma and for quantifying the beta cell mass. The existing clinical tracers targeting GLP-1R are all agonists with low specific activity and very high kidney uptake. In order to solve those issues we evaluated GLP-1R agonist Ex-4 and antagonist Ex(9–39) radioiodinated at Tyr40 side by side with [Nle14,Lys40(Ahx-DOTA-68Ga)NH2]Ex-4 (68Ga-Ex-4) used in the clinic. The Kd, Bmax, internalization and binding kinetics of [Nle14,125I-Tyr40-NH2]Ex-4 and [Nle14,125I-Tyr40-NH2]Ex(9–39) were studied in vitro using Ins-1E cells. Biodistribution and imaging studies were performed in nude mice bearing Ins-1E xenografts. In vitro evaluation demonstrated high affinity binding of the [Nle14,125I-Tyr40-NH2]Ex-4 agonist to the Ins-1E cells with fast internalization kinetics reaching a plateau after 30 min. The antagonist [Nle14,125I-Tyr40-NH2]Ex(9–39) did not internalize and had a 4–fold higher Kd value compared to the agonist. In contrast to [Nle14,125I-Tyr40-NH2]Ex(9–39), which showed low and transient tumor uptake, [Nle14,125I-Tyr40-NH2]Ex-4 demonstrated excellent in vivo binding properties with tumor uptake identical to that of 68Ga-Ex-4, but substantially lower kidney uptake resulting in a tumor-to-kidney ratio of 9.7 at 1 h compared to 0.3 with 68Ga-Ex-4. Accumulation of activity in thyroid and stomach for both peptides, which was effectively blocked by irenat, confirms that in vivo deiodination is the mechanism behind the low kidney retention of iodinated peptides. The 124I congener of [Nle14,125I-Tyr40-NH2]Ex-4 demonstrated a similar favourable biodistribution profile in the PET imaging studies in contrast to the typical biodistribution pattern of [Nle14,Lys40(Ahx-DOTA-68Ga)NH2]Ex-4. Our results demonstrate that iodinated Ex-4 is a very promising tracer for imaging of benign insulinomas. It solves the problem of high kidney uptake of the radiometal-labelled tracers by improving the tumor

  11. AMP Is an Adenosine A1 Receptor Agonist*

    PubMed Central

    Rittiner, Joseph E.; Korboukh, Ilia; Hull-Ryde, Emily A.; Jin, Jian; Janzen, William P.; Frye, Stephen V.; Zylka, Mark J.

    2012-01-01

    Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5′-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5′-monophosphonate, ACP) directly activated the adenosine A1 receptor (A1R). In contrast, AMP only activated the adenosine A2B receptor (A2BR) after hydrolysis to adenosine by ecto-5′-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A1R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A1R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A1R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A1R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine. PMID:22215671

  12. Gene Therapy for Osteoarthritis: Pharmacokinetics of Intra-articular scAAV.IL-1Ra Delivery in an Equine Model.

    PubMed

    Watson Levings, Rachael; Broome, Ted A; Smith, Andrew D; Rice, Brett L; Gibbs, Eric P; Myara, D Alex; Hyddmark, E Viktoria; Nasri, Elham; Zarezadeh, Ali; Levings, Padraic P; Lu, Yuan; Dacanay, E Anthony; Foremny, Gregory B; Evans, Christopher H; Morton, Alison J; Winter, Mathew; Dark, Michael J; Nickerson, David M; Colahan, Patrick T; Ghivizzani, Steven Craig

    2018-06-05

    142: Toward the treatment of osteoarthritis (OA), we have been investigating self-complementary adeno-associated virus (scAAV) for intra-articular delivery of gene products with therapeutic potential. As OA frequently affects weight-bearing joints, we performed pharmacokinetic studies in the equine forelimb to identify parameters of scAAV gene delivery relevant to clinical translation. Using the coding sequence for interleukin-1 receptor antagonist (IL-1Ra) as a secreted therapeutic reporter we first generated an scAAV vector containing an optimized cDNA for equine IL-1Ra. In dosing studies in vivo we identified a putative ceiling dose of 5 x 1012 viral genomes (vg) which elevated the steady-state eqIL-1Ra in synovial fluids >50-fold for over 6 months. No adverse effects of treatment were seen, and eqIL-1Ra in serum and urine remained at background. Using 5 x 1012 vg and GFP as a cytologic marker, we compared the local and systemic distribution of vector and transduced cells in healthy joints and those with late stage, naturally-occurring OA. Strikingly, a substantial increase in transgenic expression was associated with the articular pathologies characteristic of OA, including synovitis, osteophyte formation and damaged cartilage. Nonetheless, in both the healthy and OA environments the vector and transgene expression were effectively contained within the injected joint. 143: We are investigating self-complementary adeno-associated virus (scAAV) as a vector for intra-articular gene-delivery of IL-1Ra, and its therapeutic capacity in the treatment of osteoarthritis (OA). To model gene-transfer on a scale proportional to the human knee, a frequent site of OA incidence, we focused our studies on the joints of the equine forelimb. Using AAV2.5 capsid and equine IL-1Ra as a homologous transgene, we previously identified a functional ceiling dose of ~5 x 1012 viral genomes, which elevated the steady state levels of eqIL-1Ra in synovial fluids by more than 40-fold over

  13. Receptor-selective, peptidase-resistant agonists at neurokinin NK-1 and NK-2 receptors: new tools for investigating neurokinin function.

    PubMed

    Hagan, R M; Ireland, S J; Jordan, C C; Beresford, I J; Deal, M J; Ward, P

    1991-06-01

    The pharmacological profiles of two novel neurokinin agonists have been investigated. delta Ava[L-Pro9,N-MeLeu10]SP(7-11) (GR73632) and [Lys3,Gly8-R-gamma-lactam-Leu9] NKA(3-10) (GR64349) are potent and selective agonists at NK-1 and NK-2 receptors respectively. In the guinea-pig isolated trachea preparation, contractions induced by these agonists were largely unaffected by inclusion of peptidase inhibitors in the bathing medium, indicating that these agonists are resistant to metabolism by peptidases. In the anaesthetised guinea-pig, both agonists were more potent bronchoconstrictor agents than either NKA or the SP analogue, SP methylester. In the anaesthetised rat, the NK-1 agonist, GR73632 was more potent than SP, NKA or NKB at causing the histamine-independent extravasation of plasma proteins into the skin after intradermal administration. The NK-2 agonist, GR64349 and the NK-3 agonist, senktide were without significant effect in this model. These agonists are useful tools for characterizing neurokinin receptor-mediated actions both in vitro and in vivo.

  14. Effects of exendin-4 on glucose tolerance, insulin secretion, and beta-cell proliferation depend on treatment dose, treatment duration and meal contents

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Arakawa, Masayuki; Ebato, Chie; Mita, Tomoya

    2009-12-18

    Beta-cell proliferation is regulated by various metabolic demands including peripheral insulin resistance, obesity, and hyperglycemia. In addition to enhancement of glucose-induced insulin secretion, agonists for glucagon-like peptide-1 receptor (GLP-1R) stimulate proliferation and inhibit apoptosis of beta-cells, thereby probably preserve beta-cell mass. To evaluate the beta-cell preserving actions of GLP-1R agonists, we assessed the acute and chronic effects of exendin-4 on beta-cell proliferation, mass and glucose tolerance in C57BL/6J mice under various conditions. Short-term administration of high-dose exendin-4 transiently stimulated beta-cell proliferation. Comparative transcriptomic analysis showed upregulation of IGF-1 receptor and its downstream effectors in islets. Treatment of mice with exendin-4more » daily for 4 weeks (long-term administration) and feeding high-fat diet resulted in significant inhibition of weight gain and improvement of glucose tolerance with reduced insulin secretion and beta-cell mass. These findings suggest that long-term GLP-1 treatment results in insulin sensitization of peripheral organs, rather than enhancement of beta-cell proliferation and function, particularly when animals are fed high-fat diet. Thus, the effects of exendin-4 on glucose tolerance, insulin secretion, and beta-cell proliferation largely depend on treatment dose, duration of treatment and meal contents. While GLP-1 enhances proliferation of beta-cells in some diabetic mice models, our results suggest that GLP-1 stimulates beta-cell growth only when expansion of beta-cell mass is required to meet metabolic demands.« less

  15. Evaluation of partial beta-adrenoceptor agonist activity.

    PubMed

    Lipworth, B J; Grove, A

    1997-01-01

    A partial beta-adrenoceptor (beta-AR) agonist will exhibit opposite agonist and antagonist activity depending on the prevailing degree of adrenergic tone or the presence of a beta-AR agonist with higher intrinsic activity. In vivo partial beta-AR agonist activity will be evident at rest with low endogenous adrenergic tone, as for example with chronotropicity (beta 1/beta 2), inotropicity (beta 1) or peripheral vasodilatation and finger tremor (beta 2). beta-AR blocking drugs which have partial agonist activity may exhibit a better therapeutic profile when used for hypertension because of maintained cardiac output without increased systemic vascular resistance, along with an improved lipid profile. In the presence of raised endogenous adrenergic tone such as exercise or an exogenous full agonist, beta-AR subtype antagonist activity will become evident in terms of effects on exercise induced heart rate (beta 1) and potassium (beta 2) responses. Reduction of exercise heart rate will occur to a lesser degree in the case of a beta-adrenoceptor blocker with partial beta 1-AR agonist activity compared with a beta-adrenoceptor blocker devoid of partial agonist activity. This may result in reduced therapeutic efficacy in the treatment of angina on effort when using beta-AR blocking drugs with partial beta 1-AR agonist activity. Effects on exercise hyperkalaemia are determined by the balance between beta 2-AR partial agonist activity and endogenous adrenergic activity. For predominantly beta 2-AR agonist such as salmeterol and salbutamol, potentiation of exercise hyperkalaemia occurs. For predominantly beta 2-AR antagonists such as carteolol, either potentiation or attenuation of exercise hyperkalaemia occurs at low and high doses respectively. beta 2-AR partial agonist activity may also be expressed as antagonism in the presence of an exogenous full agonist, as for example attenuation of fenoterol induced responses by salmeterol. Studies are required to investigate whether

  16. Development of a cell-based qualitative assay for detection of neutralizing anti-human interleukin-1 receptor antagonist (hIL-1Ra) antibodies in rats.

    PubMed

    Gao, Jin; Li, Jingjing; Yang, Minmin; Wu, Mingyuan; Tu, Ping; Yu, Yan; Han, Wei

    2015-01-01

    To determine the incidence of the positive neutralizing anti-human interleukin receptor antagonist (anti-IL-1Ra), a novel assay based on the proliferation of human melanoma A375.S2 cells was developed and validated. In the presence of a growth-limiting concentration of IL-1β, A375.S2 cells were able to regain proliferation following the addition of IL-1Ra in a concentration-dependent manner. This dose-response effect enabled the validation of a standard curve for calculation of the concentration of IL-1Ra or, inversely, the concentration of neutralizing anti-IL-1Ra antibodies in cell culture medium or sera. The assay used CCK-8 as an indicator of proliferation. The dose-response relationship between rhIL-1Ra (dose range of 5-75 ng/ml rhIL-1Ra) and A375.S2 cell proliferation was sigmoidal and fitted a four-parameter logistic model. The percent coefficients of variation (%CVs) of quality control samples were 12.5 and 11.9% for intra-assay repeatability and 14.5 and 19.5% for inter-assay repeatability, while the total accuracy was in the range of 97.2-103.6%. For the neutralization assay, the optimal sample dilution factor was found to be 40-fold and the reasonable standard for positive and negative decision was calculated to be 59.4% neutralization rate. The %CVs of quality control samples were 12.7 and 24.0% for intra-assay repeatability and 11.6 and 30.0% for inter-assay repeatability. Analysis using the assay showed that rats could produce neutralizing anti-IL-1Ra antibodies after repeated intramuscular injection with rhIL-1Ra, and this response was not significantly dependent on the dose injected.

  17. Plant cyclopeptide RA-V kills human breast cancer cells by inducing mitochondria-mediated apoptosis through blocking PDK1–AKT interaction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fang, Xian-Ying; Chen, Wei; Fan, Jun-Ting

    2013-02-15

    In the present paper, we examined the effects of a natural cyclopeptide RA-V on human breast cancer cells and the underlying mechanisms. RA-V significantly inhibited the growth of human breast cancer MCF-7, MDA-MB-231 cells and murine breast cancer 4T1 cells. In addition, RA-V triggered mitochondrial apoptotic pathway which was indicated by the loss of mitochondrial membrane potential, the release of cytochrome c, and the activation of caspase cascade. Further study showed that RA-V dramatically inhibited phosphorylation of AKT and 3-phosphoinositide dependent protein kinase 1 (PDK1) in MCF-7 cells. Moreover, RA-V disrupted the interaction between PDK1 and AKT in MCF-7 cells.more » Furthermore, RA-V-induced apoptosis could be enhanced by phosphatidylinositol 3-kinase inhibitor or attenuated by over-expression of AKT in all the three kinds of breast cancer cells. Taken together, this study shows that RA-V, which can induce mitochondria-mediated apoptosis, exerts strong anti-tumor activity against human breast cancer. The underlying anti-cancer mechanism of RA-V is related to the blockage of the interaction between PDK1 and AKT. - Highlights: ► Plant cyclopeptide RA-V kills human breast cancer cells. ► RA-V triggered mitochondrial apoptotic pathway in human breast cancer cells. ► RA-V inhibited phosphorylation of AKT and PDK1 in breast cancer MCF-7 cells. ► Its mechanism is related to the blockage of the interaction between PDK1 and AKT.« less

  18. An Alpha-1A Adrenergic Receptor Agonist Prevents Acute Doxorubicin Cardiomyopathy in Male Mice.

    PubMed

    Montgomery, Megan D; Chan, Trevor; Swigart, Philip M; Myagmar, Bat-Erdene; Dash, Rajesh; Simpson, Paul C

    2017-01-01

    Alpha-1 adrenergic receptors mediate adaptive effects in the heart and cardiac myocytes, and a myocyte survival pathway involving the alpha-1A receptor subtype and ERK activation exists in vitro. However, data in vivo are limited. Here we tested A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulfonamide), a selective imidazoline agonist for the alpha-1A. A61603 was the most potent alpha-1-agonist in activating ERK in neonatal rat ventricular myocytes. A61603 activated ERK in adult mouse ventricular myocytes and protected the cells from death caused by the anthracycline doxorubicin. A low dose of A61603 (10 ng/kg/d) activated ERK in the mouse heart in vivo, but did not change blood pressure. In male mice, concurrent subcutaneous A61603 infusion at 10 ng/kg/d for 7 days after a single intraperitoneal dose of doxorubicin (25 mg/kg) increased survival, improved cardiac function, heart rate, and cardiac output by echocardiography, and reduced cardiac cell necrosis and apoptosis and myocardial fibrosis. All protective effects were lost in alpha-1A-knockout mice. In female mice, doxorubicin at doses higher than in males (35-40 mg/kg) caused less cardiac toxicity than in males. We conclude that the alpha-1A-selective agonist A61603, via the alpha-1A adrenergic receptor, prevents doxorubicin cardiomyopathy in male mice, supporting the theory that alpha-1A adrenergic receptor agonists have potential as novel heart failure therapies.

  19. Cloning and characterization of the rat free fatty acid receptor GPR120: in vivo effect of the natural ligand on GLP-1 secretion and proliferation of pancreatic beta cells.

    PubMed

    Tanaka, Toshiki; Yano, Takeaki; Adachi, Tetsuya; Koshimizu, Taka-aki; Hirasawa, Akira; Tsujimoto, Gozoh

    2008-06-01

    We have recently found that GPR120, which is abundantly expressed in intestine, functions as a receptor for unsaturated long-chain free fatty acids (FFAs) and that GPR120 stimulation promotes the secretion of glucagons-like peptide-1 (GLP-1) in the mouse (Hirasawa et al., Nat Med 11:90-94, 2005). In this study, we cloned and characterized rat GPR120 (rGPR120), and then we examined the in vivo effects of acute and long-term administration of the natural ligand alpha-linolenic acid (alpha-LA). The cloned rat GPR120 complimentary DNA had a seven transmembrane structure, and a homology comparison of human, mouse, and rat GPR120 revealed that the rat GPR120 (rGPR120) shares 85 and 98% sequence identity with the human and mouse GPR120 proteins, respectively. The tissue distribution and ligand properties of rGPR120 were similar to those of mouse GPR120. In addition, alpha-LA provoked a transient increase in [Ca2+]i levels in HEK293 cells expressing rGPR120. Furthermore, administration of alpha-LA to the rat increased plasma GLP-1 levels, and long-term administration of alpha-LA led to proliferation of pancreatic beta cells, probably because of the enhanced GLP-1 secretion. These results show that rat GPR120 is a G-protein-coupled receptor whose ligand is a free fatty acid, and it may play an important role in the FFA-associated physiological responses.

  20. Comparing olive oil and C4-dietary oil, a prodrug for the GPR119 agonist, 2-oleoyl glycerol, less energy intake of the latter is needed to stimulate incretin hormone secretion in overweight subjects with type 2 diabetes.

    PubMed

    Mandøe, Mette Johannsen; Hansen, Katrine Bagge; Windeløv, Johanne Agerlin; Knop, Filip Krag; Rehfeld, Jens Frederik; Rosenkilde, Mette Marie; Holst, Jens Juul; Hansen, Harald Severin

    2018-01-12

    After digestion, dietary triacylglycerol stimulates incretin release in humans, mainly through generation of 2-monoacylglycerol, an agonist for the intestinal G protein-coupled receptor 119 (GPR119). Enhanced incretin release may have beneficial metabolic effects. However, dietary fat may promote weight gain and should therefore be restricted in obesity. We designed C4-dietary oil (1,3-di-butyryl-2-oleoyl glycerol) as a 2-oleoyl glycerol (2-OG)-generating fat type, which would stimulate incretin release to the same extent while providing less calories than equimolar amounts of common triglycerides, e.g., olive oil. We studied the effect over 180 min of (a) 19 g olive oil plus 200 g carrot, (b) 10.7 g C4 dietary oil plus 200 g carrot and (c) 200 g carrot, respectively, on plasma responses of gut and pancreatic hormones in 13 overweight patients with type 2 diabetes (T2D). Theoretically, both oil meals result in formation of 7.7 g 2-OG during digestion. Both olive oil and C4-dietary oil resulted in greater postprandial (P ≤ 0.01) glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) responses (incremental area under curve (iAUC)): iAUC GLP-1 : 645 ± 194 and 702 ± 97 pM × min; iAUC GIP : 4,338 ± 764 and 2,894 ± 601 pM × min) compared to the carrot meal (iAUC GLP-1 : 7 ± 103 pM × min; iAUC GIP : 266 ± 234 pM × min). iAUC for GLP-1 and GIP were similar for C4-dietary oil and olive oil, although olive oil resulted in a higher peak value for GIP than C4-dietary oil. C4-dietary oil enhanced secretion of GLP-1 and GIP to almost the same extent as olive oil, in spite of liberation of both 2-OG and oleic acid, which also may stimulate incretin secretion, from olive oil. Thus, C4-dietary oil is more effective as incretin releaser than olive oil per unit of energy and may be useful for dietary intervention.

  1. On the mechanism for PPAR agonists to enhance ABCA1 gene expression

    PubMed Central

    Ogata, Masaki; Tsujita, Maki; Hossain, Mohammad Anwar; Akita, Nobukatsu; Gonzalez, Frank J.; Staels, Bart; Suzuki, Shogo; Fukutomi, Tatsuya; Kimura, Genjiro; Yokoyama, Shinji

    2009-01-01

    Expression of ATP binding cassette transporter A1 (ABCA1), a major regulator of high density lipoprotein (HDL) biogenesis, is known to be up-regulated by the transcription factor liver X receptor (LXR) α, and expression is further enhanced by activation of the peroxisome proliferator activated receptors (PPARs). We investigated this complex regulatory network using specific PPAR agonists: four fibrates (fenofibrate, bezafibrate, gemfibrozil and LY518674), a PPAR δ agonist (GW501516) and a PPAR γ agonist (pioglitazone). All of these compounds increased the expression of LXRs, PPARs and ABCA1 mRNAs, and associated apoA-I-mediated lipid release in THP-1 macrophage, WI38 fibroblast and mouse fibroblast. When mouse fibroblasts lacking expression of PPAR α were examined, the effects of fenofibrate and LY518674 were markedly diminished while induction by other ligands were retained. The PPAR α promoter was activated by all of these compounds in an LXR α-dependent manner, and partially in a PPAR α-dependent manner, in mouse fibroblast. The LXR responsive element (LXRE)-luciferase activity was enhanced by all the compounds in an LXR α-dependent manner in mouse fibroblast. This activation was exclusively PPAR α-dependent by fenofibrate and LY518674, but nonexclusively by the others. We conclude that PPARs and LXRs are involved in the regulation of ABCA1 expression and HDL biogenesis in a cooperative signal transduction pathway. PMID:19201410

  2. The relationship between reinforcing effects and in vitro effects of D1 agonists in monkeys.

    PubMed

    Weed, M R; Paul, I A; Dwoskin, L P; Moore, S E; Woolverton, W L

    1997-10-01

    The reinforcing effects of many psychomotor stimulants have been related to increased dopaminergic neurotransmission and stimulation of central nervous system (CNS) dopamine (DA) receptors. Consistent with this notion, some drugs that directly stimulate DA receptors have been found to function as positive reinforcers. The present experiments were designed to examine why some, but not all, D1 receptor agonists can function as reinforcers in rhesus monkeys by comparing behavioral and CNS in vitro measures of potency and efficacy. Seven rhesus monkeys were allowed to self-administer cocaine under a progressive-ratio (PR) schedule until stable responding was established. Various doses of D1 agonists, previously reported to function as positive reinforcers, were then made available for self-administration. Stimulation of cAMP production in rhesus and rat striatal tissue was studied for these compounds and for D1 agonists previously reported not to function as positive reinforcers in monkeys (SKF 38393, SKF 77434 and S(-)-6-BrAPB). Blockade of DA uptake in rat striata was also examined for all compounds. SKF 81297, SKF 82958 and R(+)-6-BrAPB maintained responding under the PR schedule and did not differ significantly in efficacy as positive reinforcers; SKF 81297 was less potent than the other two agonists. SKF 81297, SKF 82958 and R(+)-6-BrAPB stimulated higher levels of cAMP production in rhesus striata than did SKF 38393, SKF 77434 and S(-)-6-BrAPB. In contrast, all compounds blocked DA uptake. Thus, reinforcing efficacy among D1 agonists increases with efficacy in stimulating D1 receptors.

  3. Novel agonists for serotonin 5-HT7 receptors reverse metabotropic glutamate receptor-mediated long-term depression in the hippocampus of wild-type and Fmr1 KO mice, a model of Fragile X Syndrome

    PubMed Central

    Costa, Lara; Sardone, Lara M.; Lacivita, Enza; Leopoldo, Marcello; Ciranna, Lucia

    2015-01-01

    Serotonin 5-HT7 receptors are expressed in the hippocampus and modulate the excitability of hippocampal neurons. We have previously shown that 5-HT7 receptors modulate glutamate-mediated hippocampal synaptic transmission and long-term synaptic plasticity. In particular, we have shown that activation of 5-HT7 receptors reversed metabotropic glutamate receptor-mediated long-term depression (mGluR-LTD) in wild-type (wt) and in Fmr1 KO mice, a mouse model of Fragile X Syndrome in which mGluR-LTD is abnormally enhanced, suggesting that 5-HT7 receptor agonists might be envisaged as a novel therapeutic strategy for Fragile X Syndrome. In this perspective, we have characterized the basic in vitro pharmacokinetic properties of novel molecules with high binding affinity and selectivity for 5-HT7 receptors and we have tested their effects on synaptic plasticity using patch clamp on acute hippocampal slices. Here we show that LP-211, a high affinity selective agonist of 5-HT7 receptors, reverses mGluR-LTD in wt and Fmr1 KO mice, correcting a synaptic malfunction in the mouse model of Fragile X Syndrome. Among novel putative agonists of 5-HT7 receptors, the compound BA-10 displayed improved affinity and selectivity for 5-HT7 receptors and improved in vitro pharmacokinetic properties with respect to LP-211. BA-10 significantly reversed mGluR-LTD in the CA3-CA1 synapse in wt and Fmr1KO mice, indicating that BA-10 behaved as a highly effective agonist of 5-HT7 receptors and reduced exaggerated mGluR-LTD in a mouse model of Fragile X Syndrome. On the other side, the compounds RA-7 and PM-20, respectively arising from in vivo metabolism of LP-211 and BA-10, had no effect on mGluR-LTD thus did not behave as agonists of 5-HT7 receptors in our conditions. The present results provide information about the structure-activity relationship of novel 5-HT7 receptor agonists and indicate that LP-211 and BA-10 might be used as novel pharmacological tools for the therapy of Fragile X Syndrome

  4. Cell-cycle quiescence maintains Caenorhabditis elegans germline stem cells independent of GLP-1/Notch

    PubMed Central

    Seidel, Hannah S; Kimble, Judith

    2015-01-01

    Many types of adult stem cells exist in a state of cell-cycle quiescence, yet it has remained unclear whether quiescence plays a role in maintaining the stem cell fate. Here we establish the adult germline of Caenorhabditis elegans as a model for facultative stem cell quiescence. We find that mitotically dividing germ cells—including germline stem cells—become quiescent in the absence of food. This quiescence is characterized by a slowing of S phase, a block to M-phase entry, and the ability to re-enter M phase rapidly in response to re-feeding. Further, we demonstrate that cell-cycle quiescence alters the genetic requirements for stem cell maintenance: The signaling pathway required for stem cell maintenance under fed conditions—GLP-1/Notch signaling—becomes dispensable under conditions of quiescence. Thus, cell-cycle quiescence can itself maintain stem cells, independent of the signaling pathway otherwise essential for such maintenance. DOI: http://dx.doi.org/10.7554/eLife.10832.001 PMID:26551561

  5. Implementation of Good Laboratory Practices (GLP) in basic scientific research: Translating the concept beyond regulatory compliance.

    PubMed

    Jena, G B; Chavan, Sapana

    2017-10-01

    The principles of Good Laboratory Practices (GLPs) are mainly intended for the laboratories performing studies for regulatory compliances. However, today GLP can be applied to broad disciplines of science to cater to the needs of the experimental objectives, generation of quality data and assay reproducibility. Considering its significance, it can now be applied in academics; industries as well as government set ups throughout the world. GLP is the best way to promote the reliability, reproducibility of the test data and hence facilitates the international acceptability. Now it is high time to translate and implement the concept of GLP beyond regulatory studies. Thus, it can pave the way for better understanding of scientific problems and help to maintain a good human and environmental health. Through this review, we have made an attempt to explore the uses of GLP principles in different fields of science and its acceptability as well as looking for its future perspectives. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Heavy cigarette smoking is strongly associated with rheumatoid arthritis (RA), particularly in patients without a family history of RA.

    PubMed

    Hutchinson, D; Shepstone, L; Moots, R; Lear, J T; Lynch, M P

    2001-03-01

    To investigate the potential relation between cumulative exposure to cigarette smoking in patients with or without rheumatoid arthritis (RA) and a positive family history of the disease. 239 outpatient based patients with RA were compared with 239 controls matched for age, sex, and social class. A detailed smoking history was recorded and expressed as pack years smoked. Conditional logistic regression was used to calculate the association between RA and pack years smoked. The patients with RA were also interviewed about a family history of disease and recorded as positive if a first or second degree relative had RA. The smoking history at the time of the study of the patients with RA with or without a family history of the disease was compared directly with that of their respective controls. Patients with RA with or without a family history of the disease were also compared retrospectively for current smoking at the time of disease onset. An increasing association between increased pack years smoked and RA was found. There was a striking association between heavy cigarette smoking and RA. A history for 41-50 pack years smoked was associated with RA (odds ratio (OR) 13.54, 95% confidence interval (95% CI) 2.89 to 63.38; p<0.001). The association between ever having smoked and RA was modest (OR 1.81, CI 1.22 to 2.19; p=0.002). Furthermore, cigarette smoking in the patients with RA without a positive family history of RA was more prevalent than in the patients with a positive family history of RA for ever having smoked (72% v 54%; p=0.006), the number of pack years smoked (median 25.0 v 4.0; p<0.001), and for smoking at the time of disease onset (58% v 39%; p=0.003). Heavy cigarette smoking, but not smoking itself, is strongly associated with RA requiring hospital follow up and is markedly more prevalent in patients with RA without a family history of RA.

  7. scAAV-Mediated IL-1Ra gene delivery for the Treatment of Osteoarthritis: Test of Efficacy in an Equine Model.

    PubMed

    Watson Levings, Rachael; Smith, Andrew D; Broome, Ted A; Rice, Brett L; Gibbs, Eric P; Myara, D Alex; Hyddmark, Viktoria; Nasri, Elham; Zarezadeh, Ali; Levings, Padraic P; Lu, Yuan; Dacanay, E Anthony; Foremny, Gregory B; Evans, Christopher H; Morton, Alison J; Winter, Mathew; Dark, Michael J; Nickerson, David M; Colahan, Patrick T; Ghivizzani, Steven Craig

    2018-06-05

    We are investigating self-complementary adeno-associated virus (scAAV) as a vector for intra-articular gene-delivery of IL-1Ra, and its therapeutic capacity in the treatment of osteoarthritis (OA). To model gene-transfer on a scale proportional to the human knee, a frequent site of OA incidence, we focused our studies on the joints of the equine forelimb. Using AAV2.5 capsid and equine IL-1Ra as a homologous transgene, we previously identified a functional ceiling dose of ~5 x 1012 viral genomes, which elevated the steady state levels of eqIL-1Ra in synovial fluids by more than 40-fold over endogenous production for at least 6 months. Here, using an osteochondral fragmentation model of early OA, we examined the functional capacity of scAAV.IL-1Ra gene-delivery in equine joints over a period of 12 weeks. In the disease model, transgenic eqIL-1Ra expression was several-fold higher than seen previously in healthy joints, and correlated directly with the severity of joint pathology at the time of treatment. Despite wide variation in expression, the steady-state eqIL-1Ra in synovial fluids exceeded that of IL-1 by > 400-fold in all animals, and a consistent treatment effect was observed. This included a 30-40% reduction in lameness and ~25% improvement in total joint pathology by both MRI and arthroscopic assessments, which included reduced joint effusion and synovitis, and improved repair of the osteochondral lesion. No vector-related increase in eqIL-1Ra levels in blood or urine was noted. Cumulatively our studies in the equine model indicate scAAV.IL-1Ra administration is reasonably safe and capable of sustained therapeutic IL-1Ra production intra-articularly in joints of human scale. This profile supports consideration for human testing in OA.

  8. PYY3–36 and Oxyntomodulin Can Be Additive in Their Effect on Food Intake in Overweight and Obese Humans

    PubMed Central

    Field, Benjamin C.T.; Wren, Alison M.; Peters, Veronique; Baynes, Kevin C.R.; Martin, Niamh M.; Patterson, Michael; Alsaraf, Sara; Amber, Vian; Wynne, Katie; Ghatei, Mohammad A.; Bloom, Stephen R.

    2010-01-01

    OBJECTIVE Peptide YY3–36 (PYY3–36), a Y2 receptor agonist, and oxyntomodulin, a glucagon-like peptide 1 (GLP-1) receptor agonist, are cosecreted by intestinal L-cells after each meal. Separately each hormone acts as an endogenous satiety signal and reduces appetite in humans when infused intravenously. The aim of the current study was to investigate whether the anorectic effects of PYY3–36 and oxyntomodulin can be additive. RESEARCH DESIGN AND METHODS Twelve overweight or obese human volunteers underwent a randomized, double-blinded, placebo-controlled study. An ad libitum test meal was used to measure energy intake during intravenous infusions of either PYY3–36 or oxyntomodulin or combined PYY3–36/oxyntomodulin. RESULTS Energy intake during coadministration of PYY3–36 and oxyntomodulin was reduced by 42.7% in comparison with the saline control and was significantly lower than that during infusions of either hormone alone. CONCLUSIONS The anorectic effects of PYY3–36 and oxyntomodulin can be additive in overweight and obese humans. Coadministration of Y2 receptor agonists and GLP-1 receptor agonists may be a useful treatment strategy for obesity. PMID:20357366

  9. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. 721.6120 Section 721.6120 Protection of Environment...-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. (a) Chemical substances and significant new uses...

  10. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. 721.6120 Section 721.6120 Protection of Environment...-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. (a) Chemical substances and significant new uses...

  11. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. 721.6120 Section 721.6120 Protection of Environment...-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. (a) Chemical substances and significant new uses...

  12. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. 721.6120 Section 721.6120 Protection of Environment...-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. (a) Chemical substances and significant new uses...

  13. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. 721.6120 Section 721.6120 Protection of Environment...-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. (a) Chemical substances and significant new uses...

  14. The glucagon-like peptide-2 receptor C terminus modulates beta-arrestin-2 association but is dispensable for ligand-induced desensitization, endocytosis, and G-protein-dependent effector activation.

    PubMed

    Estall, Jennifer L; Koehler, Jacqueline A; Yusta, Bernardo; Drucker, Daniel J

    2005-06-10

    Classic models of receptor desensitization and internalization have been largely based on the behavior of Family A G-protein-coupled receptors (GPCRs). The glucagon-like peptide-2 receptor (GLP-2R) is a member of the Family B glucagon-secretin GPCR family, which exhibit significant sequence and structural differences from the Family A receptors in their intracellular and extracellular domains. To identify structural motifs that regulate GLP-2R signaling and cell surface receptor expression, we analyzed the functional properties of a series of mutant GLP-2Rs. The majority of the C-terminal receptor tail was dispensable for GLP-2-induced cAMP accumulation, ERK1/2 activation, and endocytosis in transfected cells. However, progressive truncation of the C terminus reduced cell surface receptor expression, altered agonist-induced GLP-2R trafficking, and abrogated protein kinase A-mediated heterologous receptor desensitization. Elimination of the distal 21 amino acids of the receptor was sufficient to promote constitutive receptor internalization and prevent agonist-induced recruitment of beta-arrestin-2. Site-directed mutagenesis identified specific amino acid residues within the distal GLP-2R C terminus that mediate the stable association with beta-arrestin-2. Surprisingly, although the truncated mutant receptors failed to interact with beta-arrestin-2, they underwent homologous desensitization and subsequent resensitization with kinetics similar to that observed with the wild-type GLP-2R. Our data suggest that, although the GLP-2R C terminus is not required for coupling to cellular machinery regulating signaling or desensitization, it may serve as a sorting signal for intracellular trafficking. Taken together with the previously demonstrated clathrin and dynamin-independent, lipid-raft-dependent pathways for internalization, our data suggest that GLP-2 receptor signaling has evolved unique structural and functional mechanisms for control of receptor trafficking

  15. Infection rates in patients from five rheumatoid arthritis (RA) registries: contextualising an RA clinical trial programme

    PubMed Central

    Yamanaka, Hisashi; Askling, Johan; Berglind, Niklas; Franzen, Stefan; Frisell, Thomas; Garwood, Christopher; Greenberg, Jeffrey D; Ho, Meilien; Holmqvist, Marie; Novelli Horne, Laura; Inoue, Eisuke; Michaud, Kaleb; Pappas, Dimitrios A; Reed, George; Symmons, Deborah; Tanaka, Eiichi; Tran, Trung N; Verstappen, Suzanne M M; Wesby-van Swaay, Eveline; Nyberg, Fredrik

    2017-01-01

    Objective Patients with rheumatoid arthritis (RA) have an increased risk of serious infections. Comparing infection rates across RA populations is complicated by differences in background infection risk, population composition and study methodology. We measured infection rates from five RA registries globally, with the aim to contextualise infection rates from an RA clinical trials population. Methods We used data from Consortium of Rheumatology Research of North America (CORRONA) (USA), Swedish Rheumatology Quality of Care Register (Sweden), Norfolk Arthritis Register (UK), CORRONA International (multiple countries) and Institute of Rheumatology Rheumatoid Arthritis (Japan) and an RA clinical trial programme (fostamatinib). Within each registry, we analysed a main cohort of all patients with RA from January 2000 to last available data. Infection definitions were harmonised across registries. Sensitivity analyses to address potential confounding explored subcohorts defined by disease activity, treatment change and/or prior comorbidities and restriction by calendar time or follow-up. Rates of infections were estimated and standardised to the trial population for age/sex and, in one sensitivity analysis also, for Health Assessment Questionnaire (HAQ) score. Results Overall, age/sex-standardised rates of hospitalised infection were quite consistent across registries (range 1.14–1.62 per 100 patient-years). Higher and more consistent rates across registries and with the trial programme overall were seen when adding standardisation for HAQ score (registry range 1.86–2.18, trials rate 2.92) or restricting to a treatment initiation subcohort followed for 18 months (registry range 0.99–2.84, trials rate 2.74). Conclusion This prospective, coordinated analysis of RA registries provided incidence rate estimates for infection events to contextualise infection rates from an RA clinical trial programme and demonstrated relative comparability of hospitalised infection

  16. Treatment with liraglutide--a once-daily GLP-1 analog--does not reduce the bioavailability of ethinyl estradiol/levonorgestrel taken as an oral combination contraceptive drug.

    PubMed

    Jacobsen, Lisbeth V; Vouis, Jan; Hindsberger, Charlotte; Zdravkovic, Milan

    2011-12-01

    Liraglutide is a once-daily human GLP-1 analog for treatment of type 2 diabetes. Like other GLP-1 analogs, liraglutide delays gastric emptying, which could potentially affect absorption of concomitantly administered oral drugs. This study investigated the effect of liraglutide on the pharmacokinetics of the components of an oral contraceptive (ethinyl estradiol/levonorgestrel). Postmeno-pausal healthy women (n = 21) were included. A single dose of this contraceptive was administered. Blood samples for ethinyl estradiol/levonorgestrel measurements were drawn until 74 hours post dosing of the contraceptive during liraglutide and placebo treatments. The 90% confidence interval (CI) of the ratio of the area under the curve (AUC) (1.06; 90% CI, 0.99-1.13) for ethinyl estradiol (during liraglutide and placebo) was within defined limits, demonstrating equivalence. The 90% CI for the ratio of AUC for levonorgestrel was not fully contained within the limits (1.18; 90% CI, 1.04-1.34) (levonorgestrel AUC was 18% greater with liraglutide vs placebo). However, equivalence was demonstrated for levonorgestrel AUC(0-t) (1.15; 90% CI, 1.06-1.24). Equivalence was not demonstrated for maximum concentration (C(max)); values for ethinyl estradiol and levonorgestrel C(max) were 12% and 13% lower with liraglutide versus placebo, respectively. Both reached C(max) ~1.5 hours later with liraglutide. No clinically relevant reduction in bioavailability of ethinyl estradiol/levonorgestrel occurred.

  17. Selective agonists of somatostatin receptor subtype 1 or 2 injected peripherally induce antihyperalgesic effect in two models of visceral hypersensitivity in mice

    PubMed Central

    Mulak, Agata; Larauche, Muriel; Biraud, Mandy; Million, Mulugeta; Rivier, Jean; Taché, Yvette

    2014-01-01

    Somatostatin interacts with 5 G-protein-coupled receptor (sst1–5). Octreotide, a stable sst2≫3≥5 agonist, octreotide, exerts a visceral anti-hyperalgesic effect in experimental and clinical studies. Little is known on the receptor subtypes involved. We investigated the influence of the stable sst1–5 agonist, ODT8-SST and selective receptor subtype peptide agonists (3 or 10 μg/mouse) injected intraperitoneally (ip) on visceral hypersensitivity in mice induced by repeated noxious colorectal distensions (4 sets of 3 CRD, each at 55 mmHg) or corticotropin-releasing factor receptor 1 agonist, cortagine given between 2 sets of graded CRD (15, 30, 45, and 60 mmHg, 3 times each pressure). The mean visceromotor response (VMR) was assessed using a non-invasive manometry method and values were expressed as percentage of the VMR to the 1st set of CRD baseline or to the 60 mmHg CRD, respectively. ODT8-SST (10 μg) and the sst2 agonist, S-346-011 (3 and 10 μg) prevented mechanically-induced visceral hypersensitivity in the 3 sets of CRD, the sst1 agonist (10 μg) blocked only the 2nd set and showed a trend at 3 μg while the sst4 agonist had no effect. The selective sst2 antagonist, S-406-028 blocked the sst2 agonist but not the sst1 agonist effect. The sst1 agonist (3 and 10 μg) prevented cortagine-induced hypersensitivity to CRD at each pressure while the sst2 agonist at 10 μg reduced it. These data indicate that in addition to sst2, the sst1 agonist may provide a novel promising target to alleviate visceral hypersensitivity induced by mechanoreceptor sensitization and more prominently, stress-related visceral nociceptive sensitization. PMID:25451334

  18. Selective agonists of somatostatin receptor subtype 1 or 2 injected peripherally induce antihyperalgesic effect in two models of visceral hypersensitivity in mice.

    PubMed

    Mulak, Agata; Larauche, Muriel; Biraud, Mandy; Million, Mulugeta; Rivier, Jean; Taché, Yvette

    2015-01-01

    Somatostatin interacts with five G-protein-coupled receptor (sst1-5). Octreotide, a stable sst2≫3≥5 agonist, exerts a visceral anti-hyperalgesic effect in experimental and clinical studies. Little is known on the receptor subtypes involved. We investigated the influence of the stable sst1-5 agonist, ODT8-SST and selective receptor subtype peptide agonists (3 or 10μg/mouse) injected intraperitoneally (ip) on visceral hypersensitivity in mice induced by repeated noxious colorectal distensions (four sets of three CRD, each at 55mmHg) or corticotropin-releasing factor receptor 1 agonist, cortagine given between two sets of graded CRD (15, 30, 45, and 60mmHg, three times each pressure). The mean visceromotor response (VMR) was assessed using a non-invasive manometry method and values were expressed as percentage of the VMR to the 1st set of CRD baseline or to the 60mmHg CRD, respectively. ODT8-SST (10μg) and the sst2 agonist, S-346-011 (3 and 10μg) prevented mechanically induced visceral hypersensitivity in the three sets of CRD, the sst1 agonist (10μg) blocked only the 2nd set and showed a trend at 3μg while the sst4 agonist had no effect. The selective sst2 antagonist, S-406-028 blocked the sst2 agonist but not the sst1 agonist effect. The sst1 agonist (3 and 10μg) prevented cortagine-induced hypersensitivity to CRD at each pressure while the sst2 agonist at 10μg reduced it. These data indicate that in addition to sst2, the sst1 agonist may provide a novel promising target to alleviate visceral hypersensitivity induced by mechanoreceptor sensitization and more prominently, stress-related visceral nociceptive sensitization. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Expression, purification, characterization and clinical relevance of rAed a 1--a 68-kDa recombinant mosquito Aedes aegypti salivary allergen.

    PubMed

    Peng, Z; Xu, W; James, A A; Lam, H; Sun, D; Cheng, L; Simons, F E

    2001-12-01

    Accurate diagnosis of mosquito allergy has been precluded by the difficulty of obtaining salivary allergens. In this study, we expressed, purified, characterized and investigated the clinical relevance of a recombinant Aedes aegypti salivary allergen, rAed a 1. Two cDNA segments were ligated together to form the full-length Aed a 1 gene. rAed a 1 was expressed using a baculovirus/insect cell system, and purified using a combination of anion-exchange and gel-filtration chromatography. The purified rAed a 1 bound to human IgE, as detected by ELISA, ELISA inhibition tests and immunoblot analyses. Epicutaneous tests with rAed a 1 and a commercial whole-body AE: aegypti extract, and AE: aegypti bite tests were performed in 48 subjects. Nine of 31 (29%) of the subjects with positive immediate bite tests also had a positive rAed a 1 immediate skin reaction and 32% had an positive immediate test to the commercial extract. Six of 33 (18%) of the subjects with positive delayed bite tests also had a positive rAed a 1 delayed skin reaction and 6% had a positive delayed test to the commercial extract. Furthermore, rAed a 1-induced flare sizes significantly correlated with mosquito bite-induced flare sizes. None of the subjects with negative bite tests had a positive skin test to rAed a 1 or to commercial extract. We conclude that the rAed a 1 has identical antigenicity and biological activity to native Aed a 1, can be used in the in vitro and in vivo diagnosis of mosquito allergy, and is more sensitive than mosquito whole-body extract for detecting delayed skin reactions.

  20. A preliminary in vitro study into the use of IL-1Ra gene therapy for the inhibition of intervertebral disc degeneration

    PubMed Central

    Le Maitre, Christine L; Freemont, Anthony J; Hoyland, Judith A

    2006-01-01

    Conventional therapies for low back pain (LBP) are purely symptomatic and do not target the cause of LBP, which in approximately 40% of cases is caused by degeneration of the intervertebral disc (DIVD). Targeting therapies to inhibit the process of degeneration would be a potentially valuable treatment for LBP. There is increasing evidence for a role for IL-1 in DIVD. A natural inhibitor of IL-1 exists, IL-1Ra, which would be an ideal molecular target for inhibiting IL-1-mediated effects involved in DIVD and LBP. In this study, the feasibility of ex vivo gene transfer of IL-1Ra to the IVD was investigated. Monolayer and alginate cultures of normal and degenerate human intervertebral disc (IVD) cells were infected with an adenoviral vector carrying the IL-1Ra gene (Ad-IL-1Ra) and protein production measured using an enzyme-linked immunosorbent assay. The ability of these infected cells to inhibit the effects of IL-1 was also investigated. In addition, normal and degenerate IVD cells infected with Ad-IL-1Ra were injected into degenerate disc tissue explants and IL-1Ra production in these discs was assessed. This demonstrated that both nucleus pulposus and annulus fibrosus cells infected with Ad-IL-1Ra produced elevated levels of IL-1Ra for prolonged time periods, and these infected cells were resistant to IL-1. When the infected cells were injected into disc explants, IL-1Ra protein expression was increased which was maintained for 2 weeks of investigation. This in vitro study has shown that the use of ex vivo gene transfer to degenerate disc tissue is a feasible therapy for the inhibition of IL-1-mediated events during disc degeneration. PMID:16436110

  1. Body Weight Gain and Hyperphagia After Administration of SGLT-2 Inhibitor: A Case Report

    PubMed Central

    Hamamoto, Hiromi; Noda, Mitsuhiko

    2015-01-01

    Patient: Male, 44 Final Diagnosis: Type 2 diabetes Symptoms: Hunger • increased appetite Medication: GLP-1 receptor agonist • SGLT-2 inhibitor Clinical Procedure: — Specialty: Internal Medicine/Diabetology Objective: Unusual or unexpected effect of treatment Background: A detailed description is given of a case we encountered in which unexpectedly marked weight gain occurred following a treatment switch from a GLP-1 receptor agonist to an SGLT-2 inhibitor. Case Report: The patient, a 44-year-old man with type 2 diabetes mellitus, had gained about 10 kg in weight in the previous year. Therefore, metformin was replaced with liraglutide to obtain reduction of body weight. Although the patient lost about 8 kg (7%), during the 18-month period on the medication, the weight loss stabilized; therefore, the treatment was again switched to tofogliflozin to obtain further reduction of body weight. However, the patient reported increasing hunger and an exaggerated appetite from week 3 onward after the start of tofogliflozin, and gained about 9 kg in weight within 2 weeks, associated with a tendency towards increased HbA1c; therefore, tofogliflozin was discontinued. Immediate reinstitution of liraglutide resulted in reduction of the increased appetite, weight, and HbA1c level. Conclusions: Caution should be exercised against hyperphagia and weight gain due to hunger that may occur following discontinuation of a GLP-1 receptor agonist and/or initiation of an SGLT-2 inhibitor. PMID:26638727

  2. Imidazopyridine CB2 agonists: optimization of CB2/CB1 selectivity and implications for in vivo analgesic efficacy.

    PubMed

    Trotter, B Wesley; Nanda, Kausik K; Burgey, Christopher S; Potteiger, Craig M; Deng, James Z; Green, Ahren I; Hartnett, John C; Kett, Nathan R; Wu, Zhicai; Henze, Darrell A; Della Penna, Kimberly; Desai, Reshma; Leitl, Michael D; Lemaire, Wei; White, Rebecca B; Yeh, Suzie; Urban, Mark O; Kane, Stefanie A; Hartman, George D; Bilodeau, Mark T

    2011-04-15

    A new series of imidazopyridine CB2 agonists is described. Structural optimization improved CB2/CB1 selectivity in this series and conferred physical properties that facilitated high in vivo exposure, both centrally and peripherally. Administration of a highly selective CB2 agonist in a rat model of analgesia was ineffective despite substantial CNS exposure, while administration of a moderately selective CB2/CB1 agonist exhibited significant analgesic effects. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Agonist-induced modulation of inverse agonist efficacy at the beta 2-adrenergic receptor.

    PubMed

    Chidiac, P; Nouet, S; Bouvier, M

    1996-09-01

    Sustained stimulation of several G protein-coupled receptors is known to lead to a reduction in the signaling efficacy. This phenomenon, named agonist-induced desensitization, has been best studied for the beta 2-adrenergic receptor (AR) and is characterized by a decreased efficacy of beta-adrenergic agonists to stimulate the adenylyl cyclase activity. Recently, several beta-adrenergic ligands were found to inhibit the spontaneous agonist-independent activity of the beta 2AR. These compounds, termed inverse agonists, have different inhibitory efficacies, ranging from almost neutral antagonists to full inverse agonists. The current study was undertaken to determine whether, as is the case for agonists, desensitization can affect the efficacies of inverse agonists. Agonist-promoted desensitization of the human beta 2AR expressed in Sf9 cells potentiated the inhibitory actions of the inverse agonists, with the extent of the potentiation being inversely proportional to their intrinsic activity. For example, desensitization increased the inhibitory action of the weak inverse agonist labetalol by 29%, whereas inhibition of the spontaneous activity by the strong inverse agonist timolol was not enhanced by the desensitizing stimuli. Interestingly, dichloroisoproterenol acted stochastically as either a weak partial agonist or a weak inverse agonist in control conditions but always behaved as an inverse agonist after desensitization. These data demonstrate that like for agonists, the efficacies of inverse agonists can be modulated by a desensitizing treatment. Also, the data show that the initial state of the receptor can determine whether a ligand behaves as a partial agonist or an inverse agonist.

  4. M1 muscarinic agonists can modulate some of the hallmarks in Alzheimer's disease: implications in future therapy.

    PubMed

    Fisher, Abraham; Pittel, Zipora; Haring, Rachel; Bar-Ner, Nira; Kliger-Spatz, Michal; Natan, Niva; Egozi, Inbal; Sonego, Hagar; Marcovitch, Itzhak; Brandeis, Rachel

    2003-01-01

    M1 muscarinic receptors (M1 mAChRs) play a role in an apparent linkage of three major hallmarks of Alzheimer's disease (AD): beta-amyloid (Abeta) peptide; tau hyperphosphorylation and paired helical filaments (PHFs); and loss of cholinergic function conducive to cognitive impairments. We evaluated the M1 muscarinic agonists AF102B (Cevimeline, EVOXAC trade mark : prescribed for Sjøgren's syndrome), AF150(S), and AF267B on some of these hallmarks of AD. Activation of M1 mAChRs with these agonists leads, inter alia, to enhanced secretion of amyloid precursor protein (alpha-APP), (via alpha-secretase activation), to decreased Abeta (via gamma-secretase inhibition), and to inhibition of Abeta- and/or oxidative stress-induced cell death. In several animal models mimicking different aspects of AD, these drugs restored cognitive impairments, and in select cases induced a decrease in brain Abeta elevation, with a high safety margin, following po administration. Notably, in mice with small hippocampi, unlike rivastigmine and nicotine, AF150(S) and AF267B restored cognitive impairments also on escape latency in a Morris water maze paradigm, in reversal learning. Studies from other labs showed that AF102B and talsaclidine (another M1 agonist) decreased cerbrospinal fluid (CSF) Abeta in AD patients following chronic treatment, being the first reported drugs with such a profile. The clinical significance of these studies remains to be elucidated, yet based on in vivo (rabbits) and in vitro studies (cell cultures), our M1 agonists can decrease brain Abeta, owing to a novel and dual complementary effect (e.g., inhibition of gamma-secretase and activation of alpha-secretase). Remarkably, although M1 agonists can decrease CSF Abeta in AD patients, an increased AD-type pathology in Parkinson's disease was recently been associated with chronic antimuscarinic treatment. In another aspect, these agonists decreased tau hyperphosphorylation in vitro and in vivo. Notably, nicotinic

  5. Amide Analogues of CD1d Agonists Modulate iNKT-Cell-Mediated Cytokine Production

    PubMed Central

    2012-01-01

    Invariant natural killer T (iNKT) cells are restricted by the non-polymorphic MHC class I-like protein, CD1d, and activated following presentation of lipid antigens bound to CD1d molecules. The prototypical iNKT cell agonist is α-galactosyl ceramide (α-GalCer). CD1d-mediated activation of iNKT cells by this molecule results in the rapid secretion of a range of pro-inflammatory (Th1) and regulatory (Th2) cytokines. Polarization of the cytokine response can be achieved by modifying the structure of the glycolipid, which opens up the possibility of using CD1d agonists as therapeutic agents for a range of diseases. Analysis of crystal structures of the T-cell receptor−α-GalCer–CD1d complex led us to postulate that amide isosteres of known CD1d agonists should modulate the cytokine response profile upon iNKT-cell activation. To this end, we describe the synthesis and biological activity of amide analogues of α-GalCer and its non-glycosidic analogue threitol ceramide (ThrCer). All of the analogues were found to stimulate murine and human iNKT cells by CD1d-mediated presentation to varying degrees; however, the thioamide and carbamate analogues of ThrCer were of particular interest in that they elicited a strongly polarized cytokine response (more interferon-gamma (IFN-γ), no interleukin-4 (IL-4)) in mice. While the ThrCer-carbamate analogue was shown to transactivate natural killer (NK) cells, a mechanism that has been used to account for the preferential production of IFN-γ by other CD1d agonists, this pathway does not account for the polarized cytokine response observed for the thioamide analogue. PMID:22324848

  6. The rabbit iris sphincter contains NK1 and NK3 but not NK2 receptors: a study with selective agonists and antagonists.

    PubMed

    Wang, Z Y; Håkanson, R

    1993-04-08

    Tachykinin analogues, claimed to be selective NK1, NK2 and NK3 receptor agonists, contracted the isolated rabbit iris sphincter muscle in a concentration-dependent manner. The contractions were not modified by the enkephalinase inhibitor thiorphan and the angiotensin-converting enzyme inhibitor captopril (10(-5) M of each). The pD2 values for (Sar9,Met(O2)11)SP (NK1 receptor agonist), (Nle10)NKA(4-10) (NK2 receptor agonist) and (MePhe7)NKB (NK3 receptor agonist) were 8.3, 6.1 and 8.2, respectively. (Sar9,Met(O2)11)SP was the most efficacious of the three agonists. The results are compatible with the presence of NK1 and NK3 receptors. The low pD2 value for the NK2 agonist may reflect a lack of NK2 receptors and interaction of the NK2 agonist with NK1 receptors. The contraction caused by the NK1 receptor agonist was inhibited competitively by the highly selective NK1 receptor antagonist (+/-) CP-96,345; the pA2 value was 5.5. Also the contraction caused by the NK2 receptor agonist was inhibited competitively by (+/-) CP-96,345 with a pA2 value of 5.7, supporting the view that the two agonists (Sar9,Met(O2)11)SP and (Nle10)NKA(4-10) interact with the same receptor. The selective NK2 receptor antagonist actinomycin D did not affect the contraction caused by the NK2 receptor agonist. We conclude that the rabbit iris sphincter muscle contains NK1 and probably NK3 receptors. We obtained no evidence for the presence of NK2 receptors.

  7. Chemokine expression in rheumatoid arthritis (RA): evidence of RANTES and macrophage inflammatory protein (MIP)-1 beta production by synovial T cells.

    PubMed Central

    Robinson, E; Keystone, E C; Schall, T J; Gillett, N; Fish, E N

    1995-01-01

    Earlier studies from this laboratory provided evidence for restricted cytokine expression in the T cell population in RA tissues. Specifically, IL-2, IL-4, IL-6 and interferon-gamma (IFN-gamma) gene expression levels were low. The selective chemoattractant and activation effects of chemokines on leucocytes identify them as potentially ideal candidates in mediating selective inflammatory processes in RA. Accordingly, we undertook studies to examine constitutive chemokine gene expression in RA tissues. RANTES, monocyte chemotactic protein-1 (MCP-1) and MIP-1 beta gene expression was examined in both the T and non-T cell populations in RA peripheral blood (PB), synovial fluid (SF) and synovial tissues (ST). Our results identified elevated levels of both RANTES and MIP-1 beta gene expression in circulating RA PB and SF T cells. By contrast, MCP-1 expression was virtually absent in RA PB, yet elevated MCP-1 mRNA levels were detected primarily in the non-T cell populations of the SF and ST samples. Histological examination of affected rheumatoid joints revealed extensive RANTES and MIP-1 beta expression in sites of lymphocyte infiltration and cell proliferation, namely the synovial lining and sublining layers. Fractionation or RA ST patient samples revealed that RANTES expression was restricted to the T cells, whereas MIP-1 beta expression was detected in both T and non-T fractions. These data suggest that MCP-1, MIP-1 beta and RANTES may have a central role in the trafficking of reactive molecules involved in immunoregulation and in the inflammatory processes in RA. Images Fig. 4 PMID:7545093

  8. IL-1ra alleviates inflammatory hyperalgesia through preventing phosphorylation of NMDA receptor NR-1 subunit in rats.

    PubMed

    Zhang, Rui-Xin; Li, Aihui; Liu, Bing; Wang, Linbo; Ren, Ke; Zhang, Haiqing; Berman, Brian M; Lao, Lixing

    2008-04-01

    Although it has been shown that pro-inflammatory cytokines such as interleukin-1beta (IL-1beta) facilitate perception of noxious inputs at the spinal level, the mechanisms have not been understood. This study determined the cell type that produces IL-1beta, the co-localization of IL-1 receptor type I (IL-1RI) and Fos and NR1 in the spinal cord, and the effects of IL-1 receptor antagonist (IL-1ra) on NR1 phosphorylation and hyperalgesia in a rat model of inflammatory pain. Phosphorylation of NR1, an essential subunit of the NMDA receptor (NMDAR), is known to modulate NMDAR activity and facilitate pain. Hyperalgesia was induced by injecting complete Freund's adjuvant (CFA, 0.08ml, 40microg Mycobacterium tuberculosis) into one hind paw of each rat. Paw withdrawal latency (PWL) was tested before CFA (-48h) for baseline and 2 and 24h after CFA to assess hyperalgesia. IL-1ra was given (i.t.) 24h before CFA to block the action of basal IL-1beta and 2h prior to each of two PWL tests to block CFA-induced IL-1beta. Spinal cords were removed for double immunostaining of IL-1beta/neuronal marker and IL-1beta/glial cell markers, IL-1RI/Fos and IL-1RI/NR1, and for Western blot to measure NR1 phosphorylation. The data showed that: (1) astrocytes produce IL-1beta, (2) IL-1RI is localized in Fos- and NR1-immunoreactive neurons within the spinal dorsal horn, and (3) IL-1ra at 0.01mg/rat significantly increased PWL (P<0.05) and inhibited NR1 phosphorylation compared to saline control. The results suggest that spinal IL-1beta is produced by astrocytes and enhances NR1 phosphorylation to facilitate inflammatory pain.

  9. Effects of different starch source of starter on small intestinal growth and endogenous GLP-2 secretion in preweaned lambs.

    PubMed

    Sun, Daming; Li, Hongwei; Mao, Shengyong; Zhu, Weiyun; Liu, Junhua

    2018-02-15

    The objective of this study was to investigate the effects of different sources of starch in starter feed on small intestinal growth and endogenous glucagon-like peptide 2 (GLP-2) secretion in preweaned lambs. Twenty-four 10-d-old lambs were divided into three groups that were treated with different iso-starch diets containing purified cassava starch (CS, n = 8), maize starch (MS, n = 8), and pea starch (PS, n = 8). At 56 d old, there was no significant difference in final body weight (BW) of lambs among the three groups. However, different starch source in starter significantly affected the average daily feed intake (ADFI) and average daily gain (ADG) of lambs among three groups. Compared with the CS and MS diets, the PS diet significantly increased the GLP-2 concentration in blood plasma (P < 0.001), the crypt depth of the jejunum (P = 0.006), and the villus height of the ileum (P = 0.039). Meanwhile, PS diet significantly increased the mRNA expression of proglucagon and the glucagon-like peptide 2 receptor (GLP-2R) in the jejunum and ileum (P < 0.001). Furthermore, the PS diet significantly upregulated the mRNA expression of cyclin D1 (P < 0.001), cyclin E (P = 0.006), and cyclin-dependent kinases 6 (CDK6) (P = 0.048) in the jejunum and cyclin A (P < 0.001), cyclin D1 (P < 0.001), and CDK6 (P = 0.002) in the ileum. Correlation analysis showed that endogenous GLP-2 secretion was positively related to the mRNA levels of cell cycle proteins in small intestinal mucosa. In summary, all results showed that PS in starter feed promoted small intestinal growth that may, in part, be related to cell cycle acceleration and endogenous GLP-2 secretion in preweaned lambs. These findings provide new insights into nutritional interventions that promote the development of small intestines in young ruminants.

  10. Ghrelin receptor (GHS-R1A) agonists show potential as interventive agents during aging.

    PubMed

    Smith, Roy G; Sun, Yuxiang; Jiang, Hong; Albarran-Zeckler, Rosie; Timchenko, Nikolai

    2007-11-01

    Administration of an orally active agonist (MK-0677) of the growth hormone secretagogue receptor (GHS-R1a) to elderly subjects restored the amplitude of endogenous episodic growth hormone (GH) release to that of young adults. Functional benefits include increased lean mass and bone density and modest improvements in strength. In old mice, a similar agonist partially restored function to the thymus and reduced tumor cell growth and metastasis. Treatment of old mice with the endogenous GHS-R1a agonist ghrelin restored a young liver phenotype. The mechanism involves inhibition of cyclin D3:cdk4/cdk6 activity and increased protein phosphatase-2A (PP2A) activity in liver nuclei, which stabilizes the dephosphorylated form of the transcription factor C/EBPalpha preventing the age-dependent formation of the C/EBPalpha-Rb-E2F4-Brm nuclear complex. By inhibiting formation of this complex, repression of E2F target genes is de-repressed and C/EBPalpha regulated expression of Pepck, a regulator of gluconeogenesis, is normalized, thereby restoring a young liver phenotype. In the brain, aging is associated with decline in dopamine function. We investigated the potential neuromodulatory role of GHS-R1a on dopamine action. Neurons were identified in the hippocampus, cortex, substantia nigra, and ventral tegmental areas that coexpressed GHS-R1a and dopamine receptor subtype-1 (D1R). Cell culture studies showed that, in the presence of ghrelin and dopamine, GHS-R and D1R form heterodimers, which modified G-protein signal transduction resulting in amplification of dopamine signaling. We speculate that aging is associated with deficient endogenous ghrelin signaling that can be rescued by intervention with GHS-R1a agonists to improve quality of life and maintain independence.

  11. The selective V1a receptor agonist selepressin (FE 202158) blocks vascular leak in ovine severe sepsis

    PubMed Central

    Wiśniewska, Halina; Traber, Lillian D.; Lin, ChiiDean; Fan, Juanjuan; Hawkins, Hal K.; Cox, Robert A.; Wiśniewski, Kazimierz; Schteingart, Claudio D.; Landry, Donald W.; Rivière, Pierre J.-M.; Traber, Daniel L.

    2014-01-01

    Objective To determine if the selective vasopressin type 1a receptor (V1aR) agonist selepressin (FE 202158) is as effective as the mixed V1a/V2 receptor (V1aR/V2R) agonist vasopressor hormone arginine vasopressin (AVP) when used as a titrated first-line vasopressor therapy in an ovine model of Pseudomonas aeruginosa pneumonia-induced severe sepsis. Design Prospective, randomized, controlled laboratory experiment. Setting University animal research facility. Subjects Forty-five chronically instrumented sheep. Interventions Sheep were anesthetized, insufflated with cooled cotton smoke via tracheostomy, and P. aeruginosa were instilled into their airways. They were then placed on assisted ventilation, awakened, and resuscitated with lactated Ringer's solution titrated to maintain hematocrit ± 3% from baseline levels. If, despite fluid management, mean arterial pressure (MAP) fell by > 10 mm Hg from baseline levels, a continuous i.v. infusion of AVP or selepressin was titrated to raise and maintain MAP within 10 mm Hg of baseline. Effects of combination treatment of selepressin with the selective V2R agonist desmopressin were similarly investigated. Measurements and Main Results In septic sheep, MAP fell by ~30 mm Hg, systemic vascular resistance index (SVRI) decreased by ~50%, and ~7 L of fluid were retained over 24 h; this fluid accumulation was partially reduced by AVP and almost completely blocked by selepressin; combined infusion of selepressin and desmopressin increased fluid accumulation to levels similar to AVP treatment. Conclusions Resuscitation with the selective V1aR agonist selepressin blocked vascular leak more effectively than the mixed V1aR/V2R agonist AVP because of its lack of agonist activity at the V2R. PMID:24674922

  12. β2 Agonists.

    PubMed

    Billington, Charlotte K; Penn, Raymond B; Hall, Ian P

    2017-01-01

    History suggests β agonists, the cognate ligand of the β 2 adrenoceptor, have been used as bronchodilators for around 5,000 years, and β agonists remain today the frontline treatment for asthma and chronic obstructive pulmonary disease (COPD). The β agonists used clinically today are the products of significant expenditure and over 100 year's intensive research aimed at minimizing side effects and enhancing therapeutic usefulness. The respiratory physician now has a therapeutic toolbox of long acting β agonists to prophylactically manage bronchoconstriction, and short acting β agonists to relieve acute exacerbations. Despite constituting the cornerstone of asthma and COPD therapy, these drugs are not perfect; significant safety issues have led to a black box warning advising that long acting β agonists should not be used alone in patients with asthma. In addition there are a significant proportion of patients whose asthma remains uncontrolled. In this chapter we discuss the evolution of β agonist use and how the understanding of β agonist actions on their principal target tissue, airway smooth muscle, has led to greater understanding of how these drugs can be further modified and improved in the future. Research into the genetics of the β 2 adrenoceptor will also be discussed, as will the implications of individual DNA profiles on the clinical outcomes of β agonist use (pharmacogenetics). Finally we comment on what the future may hold for the use of β agonists in respiratory disease.

  13. Identification of oligomer proanthocyanidins (F2) isolated from grape seeds as a formyl peptide receptor 1 partial agonist.

    PubMed

    Yang, Jingyu; Wang, Qing; Zhao, Ruijun; Sun, Baoshan; Wang, Lihui; Hou, Yue; Li, Xiaoqin; Wu, Chunfu

    2013-04-01

    Formyl peptide receptor 1 (FPR1) plays an important role in the rapid progression of glioblastoma and has been considered as a molecular target for the treatment. Previously, we have shown that oligomer proanthocyanidins (F2, degree of polymerization 2-15), isolated from grape seeds, inhibited FPR1-mediated chemotaxis of U-87 glioblastoma cells. In the present study, we investigated the capacity of F2 to interact with FPR1. The cross attenuation of chemotaxis revealed that F2 shared FPR1 with formyl-methionyl-leucyl-phenylalanine (fMLF), which is a prototype agonist of FPR1. F2 was chemotactic for U-87 cells, and the chemotactic response was abolished when FPR1 gene was silenced or FPR1 was competitively occupied. We further show that F2 specifically blocked the binding of fluorescent agonist to FPR1. Interestingly, F2 exhibited the characteristic of a partial agonist for FPR1, as shown by its capacity to activate FPR1-mediated PI3K-PKC-MAPK pathways. Meanwhile, F2 also attenuated fMLF-triggered MAPK activation, suggesting that F2 could antagonize the effect of an agonist. Furthermore, F2 abolished the invasion of U-87 cells induced by fMLF. Thus, we have identified F2 as a novel, partial agonist for FPR1, which may be useful for glioblastoma therapy. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Toll-like receptor agonists are potent inhibitors of human immunodeficiency virus-type 1 replication in peripheral blood mononuclear cells.

    PubMed

    Buitendijk, Maarten; Eszterhas, Susan K; Howell, Alexandra L

    2014-05-01

    Innate immune responses to microbial pathogens are initiated following the binding of ligand to specific pattern recognition receptors. Each pattern recognition receptor, which includes members of the Toll-like receptor (TLR) family, is specific for a particular type of pathogen associated molecular pattern ensuring that the organism can respond rapidly to a wide range of pathogens including bacteria, viruses, and fungi. We studied the extent to which agonists to endosomal TLR could induce anti-HIV-1 activity in peripheral blood mononuclear cells (PBMCs). When agonists to TLR3, TLR7, TLR8 and TLR9 were added prior to infection with HIV-1, they significantly reduced infection of peripheral blood mononuclear cells. Interestingly, agonists to TLR8 and TLR9 were highly effective at blocking HIV replication even when added as late as 48 h or 72 h, respectively, after HIV-1 infection, indicating that the anti-viral effect was durable and long lasting. Analysis of the induction of anti-viral genes after agonist activation of TLR indicated that all of the agonists induced expression of the type I interferons and interferon stimulated genes, although to variable levels that depended on the agonist used. Interestingly, only the agonist to TLR9, ODN2395 DNA, induced expression of type II interferon and the anti-HIV proteins Apobec3G and SAMHD1. By blocking TLR activity using an inhibitor to the MyD88 adaptor protein, we demonstrated that, at least for TLR8 and TLR9, the anti-HIV activity was not entirely mediated by TLR activation, but likely by the activation of additional anti-viral sensors in HIV target cells. These findings suggest that agonists to the endosomal TLR function to induce expression of anti-HIV molecules by both TLR-mediated and non-TLR-mediated mechanisms. Moreover, the non-TLR-mediated mechanisms induced by these agonists could potentially be exploited to block HIV-1 replication in recently HIV-exposed individuals.

  15. Roles of threonine 192 and asparagine 382 in agonist and antagonist interactions with M1 muscarinic receptors

    PubMed Central

    Huang, Xi-Ping; Nagy, Peter I; Williams, Frederick E; Peseckis, Steven M; Messer, William S

    1999-01-01

    Conserved amino acids, such as Thr in transmembrane domains (TM) V and Asn in TM VI of muscarinic receptors, may be important in agonist binding and/or receptor activation. In order to determine the functional roles of Thr192 and Asn382 in human M1 receptors in ligand binding and receptor activation processes, we created and characterized mutant receptors with Thr192 or Asn382 substituted by Ala.HM1 wild-type (WT) and mutant receptors [HM1(Thr192Ala) and HM1(Asn382Ala)] were stably expressed in A9 L cells. The Kd values for 3H-(R)-QNB and Ki values for other classical muscarinic antagonists were similar at HM1(WT) and HM1(Thr192Ala) mutant receptors, yet higher at HM1(Asn382Ala) mutant receptors. Carbachol exhibited lower potency and efficacy in stimulating PI hydrolysis via HM1(Thr192Ala) mutant receptors, and intermediate agonist activity at the HM1(Asn382Ala) mutant receptors.The Asn382 residue in TM VI but not the Thr192 residue in TM V of the human M1 receptor appears to participate directly in antagonist binding. Both Thr192 and Asn382 residues are involved differentially in agonist binding and/or receptor activation processes, yet the Asn382 residue is less important than Thr192 in agonist activation of M1 receptors.Molecular modelling studies indicate that substitution of Thr192 or Asn382 results in the loss of hydrogen-bond interactions and changes in the agonist binding mode associated with an increase in hydrophobic interactions between ligand and receptor. PMID:10188986

  16. Negative cooperativity in binding of muscarinic receptor agonists and GDP as a measure of agonist efficacy

    PubMed Central

    Jakubík, J; Janíčková, H; El-Fakahany, EE; Doležal, V

    2011-01-01

    BACKGROUND AND PURPOSE Conventional determination of agonist efficacy at G-protein coupled receptors is measured by stimulation of guanosine-5′-γ−thiotriphosphate (GTPγS) binding. We analysed the role of guanosine diphosphate (GDP) in the process of activation of the M2 muscarinic acetylcholine receptor and provide evidence that negative cooperativity between agonist and GDP binding is an alternative measure of agonist efficacy. EXPERIMENTAL APPROACH Filtration and scintillation proximity assays measured equilibrium binding as well as binding kinetics of [35S]GTPγS and [3H]GDP to a mixture of G-proteins as well as individual classes of G-proteins upon binding of structurally different agonists to the M2 muscarinic acetylcholine receptor. KEY RESULTS Agonists displayed biphasic competition curves with the antagonist [3H]-N-methylscopolamine. GTPγS (1 µM) changed the competition curves to monophasic with low affinity and 50 µM GDP produced a similar effect. Depletion of membrane-bound GDP increased the proportion of agonist high-affinity sites. Carbachol accelerated the dissociation of [3H]GDP from membranes. The inverse agonist N-methylscopolamine slowed GDP dissociation and GTPγS binding without changing affinity for GDP. Carbachol affected both GDP association with and dissociation from Gi/o G-proteins but only its dissociation from Gs/olf G-proteins. CONCLUSIONS AND IMPLICATIONS These findings suggest the existence of a low-affinity agonist-receptor conformation complexed with GDP-liganded G-protein. Also the negative cooperativity between GDP and agonist binding at the receptor/G-protein complex determines agonist efficacy. GDP binding reveals differences in action of agonists versus inverse agonists as well as differences in activation of Gi/o versus Gs/olf G-proteins that are not identified by conventional GTPγS binding. PMID:20958290

  17. Negative cooperativity in binding of muscarinic receptor agonists and GDP as a measure of agonist efficacy.

    PubMed

    Jakubík, J; Janíčková, H; El-Fakahany, E E; Doležal, V

    2011-03-01

    Conventional determination of agonist efficacy at G-protein coupled receptors is measured by stimulation of guanosine-5'-γ-thiotriphosphate (GTPγS) binding. We analysed the role of guanosine diphosphate (GDP) in the process of activation of the M₂ muscarinic acetylcholine receptor and provide evidence that negative cooperativity between agonist and GDP binding is an alternative measure of agonist efficacy. Filtration and scintillation proximity assays measured equilibrium binding as well as binding kinetics of [³⁵S]GTPγS and [³H]GDP to a mixture of G-proteins as well as individual classes of G-proteins upon binding of structurally different agonists to the M₂ muscarinic acetylcholine receptor. Agonists displayed biphasic competition curves with the antagonist [³H]-N-methylscopolamine. GTPγS (1 µM) changed the competition curves to monophasic with low affinity and 50 µM GDP produced a similar effect. Depletion of membrane-bound GDP increased the proportion of agonist high-affinity sites. Carbachol accelerated the dissociation of [³H]GDP from membranes. The inverse agonist N-methylscopolamine slowed GDP dissociation and GTPγS binding without changing affinity for GDP. Carbachol affected both GDP association with and dissociation from G(i/o) G-proteins but only its dissociation from G(s/olf) G-proteins. These findings suggest the existence of a low-affinity agonist-receptor conformation complexed with GDP-liganded G-protein. Also the negative cooperativity between GDP and agonist binding at the receptor/G-protein complex determines agonist efficacy. GDP binding reveals differences in action of agonists versus inverse agonists as well as differences in activation of G(i/o) versus G(s/olf) G-proteins that are not identified by conventional GTPγS binding. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

  18. P2X receptor characterization and IL-1/IL-1Ra release from human endothelial cells.

    PubMed

    Wilson, H L; Varcoe, R W; Stokes, L; Holland, K L; Francis, S E; Dower, S K; Surprenant, A; Crossman, D C

    2007-05-01

    The pro-inflammatory cytokine, interleukin-1beta (IL-1beta), has been implicated in the pathogenesis of atherosclerosis, potentially via its release from vascular endothelium. Endothelial cells (EC) synthesize IL-1beta in response to inflammatory stimuli, but the demonstration and mechanism of release of IL-1 from ECs remains unclear. In activated monocytes, efficient release of bioactive IL-1beta occurred via activation of ATP-gated P2X(7) receptors (P2X(7)Rs). Activation of P2X(7)R in ECs from human umbilical vein (HUVECs) released IL-1 receptor antagonist (IL-1Ra). The purpose of this study was to provide a quantitative investigation of P2XR expression and function, in parallel with IL-1beta and IL-1Ra synthesis, processing and release, in HUVECs under pro-inflammatory conditions. Quantitative RT-PCR, immunoblotting, ELISA, flow cytometry, and whole-cell patch clamp recordings were used to determine protein expression and receptor function. IL-8-luciferase-reporter was used as an IL-1 sensitive bioassay. HUVECs expressed P2X(4)R and P2X(7)R subtypes and both were significantly up-regulated under inflammatory conditions. P2X(7)R currents were increased 3-fold by inflammatory stimuli, whereas no P2X(4)R-mediated currents were detected. Caspase-1, but not IL-1beta, was present intracellularly under basal conditions; inflammatory stimuli activated the synthesis of intracellular pro-IL-1beta and increased caspase-1 levels. Activation of P2X(7)Rs resulted in low-level release of bioactive IL-1beta and simultaneous release of IL-1Ra. The net biological effect of release was anti-inflammatory. Endothelial P2X(7)Rs induced secretion of both pro- and anti-inflammatory IL-1 receptor ligands, the balance of which may provide a means for altering the inflammatory state of the arterial vessel wall.

  19. The Sophomore RA Experience: An Examination of Job Satisfaction, Turnover Intentions, and RA Self-Efficacy

    ERIC Educational Resources Information Center

    Brandt Brecheisen, Shannon M.

    2014-01-01

    The purpose of this national, quantitative study was to (1) provide psychometrics for the ACUHO-I/EBI RA Survey, a joint project between between Educational Benchmarking, Inc (EBI) and The Association of College and University Housing Officers--International (ACUHO-I), and (2) explore the sophomore resident assistant (RA) experience. This study…

  20. Peroxisome proliferator-activated receptor δ agonists inhibit T helper type 1 (Th1) and Th17 responses in experimental allergic encephalomyelitis

    PubMed Central

    Kanakasabai, Saravanan; Chearwae, Wanida; Walline, Crystal C; Iams, Wade; Adams, Suzanne M; Bright, John J

    2010-01-01

    Multiple sclerosis (MS) is a neurological disorder that affects more than a million people world-wide. The aetiology of MS is not known and there is no medical treatment available that can cure MS. Experimental autoimmune encephalomyelitis (EAE) is a T-cell-mediated autoimmune disease model of MS. The pathogenesis of EAE/MS is a complex process involving activation of immune cells, secretion of inflammatory cytokines and destruction of myelin sheath in the central nervous system (CNS). Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptor transcription factors that regulate cell growth, differentiation and homeostasis. PPAR agonists have been used in the treatment of obesity, diabetes, cancer and inflammation. We and others have shown that PPARγ, α and δ agonists inhibit CNS inflammation and demyelination in the EAE model of MS. In this study we show that the PPARδ agonists GW501516 and L165041 ameliorate MOGp35-55-induced EAE in C57BL/6 mice by blocking interferon (IFN)-γ and interleukin (IL)-17 production by T helper type 1 (Th1) and Th17 cells. The inhibition of EAE by PPARδ agonists was also associated with a decrease in IL-12 and IL-23 and an increase in IL-4 and IL-10 expression in the CNS and lymphoid organs. These findings indicate that PPARδ agonists modulate Th1 and Th17 responses in EAE and suggest their use in the treatment of MS and other autoimmune diseases. PMID:20406305