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1

Opioid agonist and antagonist activities of morphindoles related to naltrindole.  

PubMed

A series of naltrindole-related ligands (4-10) with an N-methyl,N-phenethyl,N-cinnamyl, or an unsubstituted basic nitrogen were synthesized and tested for opioid agonist and antagonist activity in smooth muscle preparations and in mice. The nor compounds (4 and 6) and the phenethyl derivatives (5 and 8) displayed full agonist activity (IC50 = 85-179 nM) in the mouse vas deferens preparation (MVD) while the other members of the series exhibited partial agonist or weak antagonist activity. In the guinea pig ileum preparation (GPI), all compounds except 8 were partial agonists. The ligands that were evaluated in mice were found to produce antinociception that was not selectively mediated via delta opioid receptors. However, two of these ligands (4 and 5) appeared to be delta-selective opioid receptor antagonists at subthreshold doses for antinociception. The finding that all of the compounds bind selectively to delta opioid receptors in guinea pig brain membranes together with the in vitro pharmacology and in vivo antagonist studies suggests that the lack of delta agonist selectivity in vivo may be due to a number of factors, including a basic difference between the delta receptor system in the MVD and in the mouse brain. Further, it is suggested that the constellation of message and address components in the morphindole nucleus may tend to stabilize delta receptors in the brain in antagonist state. PMID:1333013

Portoghese, P S; Larson, D L; Sultana, M; Takemori, A E

1992-11-13

2

The atypical antidepressant mianserin exhibits agonist activity at ?-opioid receptors  

PubMed Central

BACKGROUND AND PURPOSE Antidepressants are known to interact with the opioid system through mechanisms not completely understood. We previously reported that tricyclic antidepressants act as agonists at distinct opioid receptors. Here, we investigated the effect of the atypical antidepressant mianserin at cloned and native opioid receptors. EXPERIMENTAL APPROACH Effects of mianserin were examined in CHO cells transfected with human opioid receptors, C6 glioma cells and rat brain membranes by the use of radioligand binding and functional assays including the stimulation of [35S]GTP?S binding and MAPK phosphorylation. KEY RESULTS Mianserin displayed 12- and 18-fold higher affinity for ?- than µ- and ?-opioid receptors respectively. In [35S]GTP?S assays, mianserin selectively activated ?-opioid receptors. The agonist activity was antagonized by the selective ?-opioid blocker nor-binaltorphimine (nor-BNI). The mianserin analogue mirtazapine also displayed ?-opioid agonist activity. Mianserin and mirtazapine increased ERK1/2 phosphorylation in CHO cells expressing ?-opioid receptors and C6 cells, and these effects were antagonized by nor-BNI. In rat striatum and nucleus accumbens, mianserin stimulated [35S]GTP?S binding in a nor-BNI-sensitive manner with maximal effects lower than those of the full ?-opioid agonists (–)-U50,488 and dynorphin A. When combined, mianserin antagonized the effects of the full ?-opioid receptor agonists in [35S]GTP?S assays and reduced the stimulation of p38 MAPK and ERK1/2 phosphorylation by dynorphin A. CONCLUSIONS AND IMPLICATIONS In different cell systems, mianserin directly activates ?-opioid receptors, displaying partial agonist activity at brain receptors. Thus, this property appears to be a common feature of different classes of antidepressants. PMID:22708686

Olianas, Maria C; Dedoni, Simona; Onali, Pierluigi

2012-01-01

3

Agonist-antagonist muscle activation during drop jumps.  

PubMed

Pre-programmed and stretch-induced muscle activities of agonist muscles can play important roles during stretch-shortening cycle exercises. It is still not clear how the antagonist muscles function when the drop and rebound intensities are varied during drop jump (DJ) exercises. The purpose of the present study was to examine the regulation of agonist-antagonist muscle activation during DJ with different drop and rebound heights. The subjects performed DJs with two drop heights (0.2 and 0.4 m) and three different efforts (maximal rebound height, 50% effort of maximal rebound height and landing without rebound). Ankle and knee joint angles, and vertical ground reaction force together with an electromyogram of the lower leg muscles (medial gastrocnemius [MG], soleus [SOL] and tibialis anterior [TA]) were measured simultaneously during DJ. Our results clearly showed that the pre-activation of the antagonist TA was increased with increasing rebound height. Our results further showed that the coactivations of agonist and antagonist muscles during the post-impact 30-ms phase were increased with increasing rebound height. These results suggested that not only the pre-programmed agonist MG muscle activation, but also the pre-programmed antagonist TA activation and the coactivation of the post-impact 30-ms phase may play important roles in the control of rebound height. PMID:24050466

Arai, Aya; Ishikawa, Masaki; Ito, Akira

2013-01-01

4

Covalent agonists for studying G protein-coupled receptor activation  

PubMed Central

Structural studies on G protein-coupled receptors (GPCRs) provide important insights into the architecture and function of these important drug targets. However, the crystallization of GPCRs in active states is particularly challenging, requiring the formation of stable and conformationally homogeneous ligand-receptor complexes. Native hormones, neurotransmitters, and synthetic agonists that bind with low affinity are ineffective at stabilizing an active state for crystallogenesis. To promote structural studies on the pharmacologically highly relevant class of aminergic GPCRs, we here present the development of covalently binding molecular tools activating Gs-, Gi-, and Gq-coupled receptors. The covalent agonists are derived from the monoamine neurotransmitters noradrenaline, dopamine, serotonin, and histamine, and they were accessed using a general and versatile synthetic strategy. We demonstrate that the tool compounds presented herein display an efficient covalent binding mode and that the respective covalent ligand-receptor complexes activate G proteins comparable to the natural neurotransmitters. A crystal structure of the ?2-adrenoreceptor in complex with a covalent noradrenaline analog and a conformationally selective antibody (nanobody) verified that these agonists can be used to facilitate crystallogenesis. PMID:25006259

Weichert, Dietmar; Kruse, Andrew C.; Manglik, Aashish; Hiller, Christine; Zhang, Cheng; Hubner, Harald; Kobilka, Brian K.; Gmeiner, Peter

2014-01-01

5

Covalent agonists for studying G protein-coupled receptor activation.  

PubMed

Structural studies on G protein-coupled receptors (GPCRs) provide important insights into the architecture and function of these important drug targets. However, the crystallization of GPCRs in active states is particularly challenging, requiring the formation of stable and conformationally homogeneous ligand-receptor complexes. Native hormones, neurotransmitters, and synthetic agonists that bind with low affinity are ineffective at stabilizing an active state for crystallogenesis. To promote structural studies on the pharmacologically highly relevant class of aminergic GPCRs, we here present the development of covalently binding molecular tools activating Gs-, Gi-, and Gq-coupled receptors. The covalent agonists are derived from the monoamine neurotransmitters noradrenaline, dopamine, serotonin, and histamine, and they were accessed using a general and versatile synthetic strategy. We demonstrate that the tool compounds presented herein display an efficient covalent binding mode and that the respective covalent ligand-receptor complexes activate G proteins comparable to the natural neurotransmitters. A crystal structure of the ?2-adrenoreceptor in complex with a covalent noradrenaline analog and a conformationally selective antibody (nanobody) verified that these agonists can be used to facilitate crystallogenesis. PMID:25006259

Weichert, Dietmar; Kruse, Andrew C; Manglik, Aashish; Hiller, Christine; Zhang, Cheng; Hübner, Harald; Kobilka, Brian K; Gmeiner, Peter

2014-07-22

6

Selective peroxisome proliferator-activated receptor? modulators (SPPARM?): The next generation of peroxisome proliferator-activated receptor ?-agonists  

PubMed Central

Dyslipidemia is a major risk factor for cardiovascular (CV) disease – the primary cause of death, worldwide. Although reducing levels of low-density lipoprotein-cholesterol can significantly reduce CV risk, a high level of residual risk persists, especially in people with obesity-related conditions, such as metabolic syndrome and type 2 diabetes mellitus. Peroxisome proliferator-activated receptor alpha- (PPAR?-) agonists (e.g. fibrates), play a central role in the reduction of macro- and microvascular risk in these patients. However, the currently available fibrates are weak (PPAR?-agonists) with limited efficacy due to dose-related adverse effects. To address this problem, a new generation of highly potent and selective PPAR?-modulators (SPPARM?) is being developed that separate the benefits of the PPAR?-agonists from their unwanted side effects. Among these, aleglitazar (a dual PPAR?/? agonist) and GFT505 (a dual PPAR ?/? agonist) have recently entered late-phase development. Although both compounds are more potent PPAR?-activators than fenofibrate in vitro, only aleglitezar is more effective in lowering triglycerides and raising high-density lipoprotein-cholesterol (HDL-C) in humans. However, it is also associated with a potential risk of adverse effects. More recently, a highly potent, specific PPAR?-agonist (K-877) has emerged with SPPARM? characteristics. Compared to fenofibrate, K-877 has more potent PPAR?-activating efficacy in vitro, greater effects on triglycerides- and HDL-C levels in humans, and a reduced risk of adverse effects. If successful, K-877 has the potential to supersede the fibrates as the treatment of choice for patients with residual CV risk associated with metabolic syndrome and type 2 diabetes. PMID:23721199

2013-01-01

7

Antipruritic activity of the ?-opioid receptor agonist, TRK-820  

Microsoft Academic Search

The effects of the ?-opioid receptor agonist, TRK-820, (?)-17-(cyclopropylmethyl)-3, 14?-dihydroxy-4, 5?-epoxy-6?-[N-methyl-trans-3-(3-furyl) acrylamido] morphinan hydrochloride, on the itch sensation were compared with those of histamine H1 receptor antagonists, using the mouse pruritogen-induced scratching model. Peroral administration of TRK-820 reduced the numbers of substance P- or histamine-induced scratches dose dependently. No obvious suppression of the spontaneous locomotor activity was observed at the

Yuko Togashi; Hideo Umeuchi; Kiyoshi Okano; Naoki Ando; Yoshitaka Yoshizawa; Toshiyuki Honda; Kuniaki Kawamura; Takashi Endoh; Jun Utsumi; Junzo Kamei; Toshiaki Tanaka; Hiroshi Nagase

2002-01-01

8

Prostaglandin E receptor subtypes in smooth muscle: agonist activities of stable prostacyclin analogues.  

PubMed Central

The agonist activities of a range of prostaglandin analogues on smooth muscle preparations sensitive to prostaglandin E2 (PGE2) have been investigated. When necessary thromboxane-like activity was eliminated using the thromboxane receptor antagonists EP 045 and EP 092. On the bullock iris sphincter, rat stomach fundus and guinea-pig trachea, (+/-) omega-tetranor-16-p-chlorophenoxy PGE2 (ICI 80205) and 16,16-dimethyl PGE2 were more active contractile agents than PGE2, whereas for relaxant activity on the cat trachea, guinea-pig trachea and dog hind limb arterial vessels in vivo the order of potency was reversed. 11-Deoxy PGE1 exhibited greater relaxant than contractile activity when compared to PGE2. Iloprost and 6a-carba-delta 6,6aPGI1 (potent mimetics of PGI2) showed high contractile activity on the PGE-sensitive preparations. PGI2 was less active and another potent PGI2 mimetic, ZK 96480, showed only very weak activity. When tested, the dibenzoxazepines SC 19220 and SC 25191 blocked the contractile actions of iloprost and 6a-carba-delta 6,6aPGI1 and those of PGE2 and 16,16-dimethyl PGE2 to similar extents. Each of the PGI2 analogues showed weak activity on the relaxant systems. On the proximal portion of the ascending colon of the rat, PGI2, iloprost, 6a-carba-delta 6,6aPGI1 and ZK 96480 always inhibited spontaneous activity at nanomolar concentrations. PGE2 and PGE1 showed weak contractile activity. The distal portion of the ascending colon was more responsive to the contractile action of PGE analogues: both iloprost and 6a-carba-delta 6,6aPGI1 showed evidence of contractile activity, whereas PGI2 and ZK 96480 always inhibited spontaneous activity. Evidence was obtained that the rat stomach fundus also contains a PGF receptor; (+/-) omega-tetranor-16-m-trifluoromethylphenoxy PGF2 alpha (ICI 81008) acted as a specific agonist. PGF2 alpha and its omega-tetranor-16-p-fluorophenoxy analogue produced a higher maximum response that ICI 81008 probably due to their additional agonist action at the PGE receptor. The data support the hypothesis that there are two subtypes of the PGE receptor. ZK 96480 has minimal activity on both receptor subtypes and appears to be a highly specific PGI2 mimetic. PMID:2420404

Dong, Y. J.; Jones, R. L.; Wilson, N. H.

1986-01-01

9

Medium Chain Fatty Acids Are Selective Peroxisome Proliferator Activated Receptor (PPAR) ? Activators and Pan-PPAR Partial Agonists  

PubMed Central

Thiazolidinediones (TZDs) act through peroxisome proliferator activated receptor (PPAR) ? to increase insulin sensitivity in type 2 diabetes (T2DM), but deleterious effects of these ligands mean that selective modulators with improved clinical profiles are needed. We obtained a crystal structure of PPAR? ligand binding domain (LBD) and found that the ligand binding pocket (LBP) is occupied by bacterial medium chain fatty acids (MCFAs). We verified that MCFAs (C8–C10) bind the PPAR? LBD in vitro and showed that they are low-potency partial agonists that display assay-specific actions relative to TZDs; they act as very weak partial agonists in transfections with PPAR? LBD, stronger partial agonists with full length PPAR? and exhibit full blockade of PPAR? phosphorylation by cyclin-dependent kinase 5 (cdk5), linked to reversal of adipose tissue insulin resistance. MCFAs that bind PPAR? also antagonize TZD-dependent adipogenesis in vitro. X-ray structure B-factor analysis and molecular dynamics (MD) simulations suggest that MCFAs weakly stabilize C-terminal activation helix (H) 12 relative to TZDs and this effect is highly dependent on chain length. By contrast, MCFAs preferentially stabilize the H2-H3/?-sheet region and the helix (H) 11-H12 loop relative to TZDs and we propose that MCFA assay-specific actions are linked to their unique binding mode and suggest that it may be possible to identify selective PPAR? modulators with useful clinical profiles among natural products. PMID:22649490

Ayers, Steven D.; Lin, Jean Z.; Cvoro, Aleksandra; Silveira, Rodrigo L.; Martinez, Leandro; Souza, Paulo C. T.; Saidemberg, Daniel; Deng, Tuo; Amato, Angela Angelica; Togashi, Marie; Hsueh, Willa A.; Phillips, Kevin; Palma, Mario Sergio; Neves, Francisco A. R.; Skaf, Munir S.; Webb, Paul; Polikarpov, Igor

2012-01-01

10

Design and Evaluation of a Biomimetic Agonist-Antagonist Active Knee Prosthesis  

E-print Network

Design and Evaluation of a Biomimetic Agonist-Antagonist Active Knee Prosthesis by ARCHIVES Ernesto;Design and Evaluation of a Biomimetic Agonist-Antagonist Active Knee Prosthesis by Ernesto Carlos. This thesis presents the design and evaluation of a novel biomimetic active knee prosthesis capable

Herr, Hugh

11

Modulating human proteinase activated receptor 2 with a novel antagonist (GB88) and agonist (GB110)  

PubMed Central

BACKGROUND AND PURPOSE Many cells express proteinase activated receptor 2 (PAR2) on their plasma membrane. PAR2 is activated by proteolytic enzymes, such as trypsin and tryptase that cleave the receptor N-terminus, inititating signalling to intracellular G proteins. Studies on PAR2 have relied heavily upon activating effects of proteases and peptide agonists that lack stability and bioavailability in vivo. EXPERIMENTAL APPROACH A novel small molecule agonist GB110 and an antagonist GB88 were characterized in vitro against trypsin, peptide agonists, PAR2 antibody, PAR1 agonists and flow cytometry,in seven cell lines using intracellular Ca2+ mobilization and examined in vivo against PAR2- and PAR1-induced rat paw oedema. KEY RESULTS GB110 is a potent non-peptidic agonist activating PAR2-mediated Ca2+ release in HT29 cells (EC50?200 nM) and six other human cell lines, inducing PAR2 internalization. GB88 is a unique PAR2 antagonist, inhibiting PAR2 activated Ca2+ release (IC50?2 µM) induced by native (trypsin) or synthetic peptide and non-peptide agonists. GB88 was a competitive and surmountable antagonist of agonist 2f-LIGRLO-NH2, a competitive but insurmountable antagonist of agonist GB110, and a non-competitive insurmountable antagonist of trypsin. GB88 was orally active and anti-inflammatory in vivo, inhibiting acute rat paw oedema elicited by agonist GB110 and proteolytic or peptide agonists of PAR2 but not by corresponding agonists of PAR1 or PAR4. CONCLUSIONS AND IMPLICATIONS The novel PAR2 agonist and antagonist modulate intracellular Ca2+ and rat paw oedema, providing novel molecular tools for examining PAR2-mediated diseases. PMID:21806599

Suen, JY; Barry, GD; Lohman, RJ; Halili, MA; Cotterell, AJ; Le, GT; Fairlie, DP

2012-01-01

12

Different skeletal effects of the peroxisome proliferator activated receptor (PPAR)? agonist fenofibrate and the PPAR? agonist pioglitazone  

PubMed Central

Background All the peroxisome proliferator activated receptors (PPARs) are found to be expressed in bone cells. The PPAR? agonist rosiglitazone has been shown to decrease bone mass in mice and thiazolidinediones (TZDs) have recently been found to increase bone loss and fracture risk in humans treated for type 2 diabetes mellitus. The aim of the study was to examine the effect of the PPAR? agonist fenofibrate (FENO) and the PPAR? agonist pioglitazone (PIO) on bone in intact female rats. Methods Rats were given methylcellulose (vehicle), fenofibrate or pioglitazone (35 mg/kg body weight/day) by gavage for 4 months. BMC, BMD, and body composition were measured by DXA. Histomorphometry and biomechanical testing of excised femurs were performed. Effects of the compounds on bone cells were studied. Results The FENO group had higher femoral BMD and smaller medullary area at the distal femur; while trabecular bone volume was similar to controls. Whole body BMD, BMC, and trabecular bone volume were lower, while medullary area was increased in PIO rats compared to controls. Ultimate bending moment and energy absorption of the femoral shafts were reduced in the PIO group, while similar to controls in the FENO group. Plasma osteocalcin was higher in the FENO group than in the other groups. FENO stimulated proliferation and differentiation of, and OPG release from, the preosteoblast cell line MC3T3-E1. Conclusion We show opposite skeletal effects of PPAR? and ? agonists in intact female rats. FENO resulted in significantly higher femoral BMD and lower medullary area, while PIO induced bone loss and impairment of the mechanical strength. This represents a novel effect of PPAR? activation. PMID:19331671

Syversen, Unni; Stunes, Astrid K; Gustafsson, Bjorn I; Obrant, Karl J; Nordsletten, Lars; Berge, Rolf; Thommesen, Liv; Reseland, Janne E

2009-01-01

13

Activation of Protease Activated Receptor 2 by Exogenous Agonist Exacerbates Early Radiation Injury in Rat Intestine  

SciTech Connect

Purpose: Protease-activated receptor-2 (PAR{sub 2}) is highly expressed throughout the gut and regulates the inflammatory, mitogenic, fibroproliferative, and nociceptive responses to injury. PAR{sub 2} is strikingly upregulated and exhibits increased activation in response to intestinal irradiation. We examined the mechanistic significance of radiation enteropathy development by assessing the effect of exogenous PAR{sub 2} activation. Methods and Materials: Rat small bowel was exposed to localized single-dose radiation (16.5 Gy). The PAR{sub 2} agonist (2-furoyl-LIGRLO-NH{sub 2}) or vehicle was injected intraperitoneally daily for 3 days before irradiation (before), for 7 days after irradiation (after), or both 3 days before and 7 days after irradiation (before-after). Early and delayed radiation enteropathy was assessed at 2 and 26 weeks after irradiation using quantitative histologic examination, morphometry, and immunohistochemical analysis. Results: The PAR{sub 2} agonist did not elicit changes in the unirradiated (shielded) intestine. In contrast, in the irradiated intestine procured 2 weeks after irradiation, administration of the PAR{sub 2} agonist was associated with more severe mucosal injury and increased intestinal wall thickness in all three treatment groups (p <.05) compared with the vehicle-treated controls. The PAR{sub 2} agonist also exacerbated the radiation injury score, serosal thickening, and mucosal inflammation (p <.05) in the before and before-after groups. The short-term exogenous activation of PAR{sub 2} did not affect radiation-induced intestinal injury at 26 weeks. Conclusion: The results of the present study support a role for PAR{sub 2} activation in the pathogenesis of early radiation-induced intestinal injury. Pharmacologic PAR{sub 2} antagonists might have the potential to reduce the intestinal side effects of radiotherapy and/or as countermeasures in radiologic accidents or terrorism scenarios.

Wang Junru; Boerma, Marjan; Kulkarni, Ashwini [Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, AR (United States); Hollenberg, Morley D. [Department of Pharmacology and Therapeutics, University of Calgary, Calgary, AB (Canada); Department of Medicine, University of Calgary, Calgary, AB (Canada); Hauer-Jensen, Martin, E-mail: mhjensen@life.uams.ed [Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, AR (United States); Surgical Service, Central Arkansas Veterans Healthcare System, Little Rock, AR (United States)

2010-07-15

14

Comparison of human B cell activation by TLR7 and TLR9 agonists  

PubMed Central

Background Human B cells and plasmacytoid dendritic cells (pDC) are the only cells known to express both TLR7 and TLR9. Plasmacytoid dendritic cells are the primary IFN-? producing cells in response to TLR7 and TLR9 agonists. The direct effects of TLR7 stimulation on human B cells is less understood. The objective of this study was to compare the effects of TLR7 and TLR9 stimulation on human B cell function. Results Gene expression and protein production of cytokines, chemokines, various B cell activation markers, and immunoglobulins were evaluated. Purified human CD19+ B cells (99.9%, containing both naïve and memory populations) from peripheral blood were stimulated with a TLR7-selective agonist (852A), TLR7/8 agonist (3M-003), or TLR9 selective agonist CpG ODN (CpG2006). TLR7 and TLR9 agonists similarly modulated the expression of cytokine and chemokine genes (IL-6, MIP1 alpha, MIP1 beta, TNF alpha and LTA), co-stimulatory molecules (CD80, CD40 and CD58), Fc receptors (CD23, CD32), anti-apoptotic genes (BCL2L1), certain transcription factors (MYC, TCFL5), and genes critical for B cell proliferation and differentiation (CD72, IL21R). Both agonists also induced protein expression of the above cytokines and chemokines. Additionally, TLR7 and TLR9 agonists induced the production of IgM and IgG. A TLR8-selective agonist was comparatively ineffective at stimulating purified human B cells. Conclusion These results demonstrate that despite their molecular differences, the TLR7 and TLR9 agonists induce similar genes and proteins in purified human B cells. PMID:18652679

Hanten, John A; Vasilakos, John P; Riter, Christie L; Neys, Lori; Lipson, Kenneth E; Alkan, Sefik S; Birmachu, Woubalem

2008-01-01

15

PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR (PPAR) AGONISTS AS PROMISING NEW MEDICATIONS FOR DRUG ADDICTION: PRECLINICAL EVIDENCE  

PubMed Central

This review examines the growing literature on the role of peroxisome proliferator-activated receptors (PPARs) in addiction. There are two subtypes of PPAR receptors that have been studied in addiction: PPAR-? and PPAR-?. The role of each PPAR subtype in common models of addictive behavior, mainly pre-clinical models, is summarized. In particular, studies are reviewed that investigated the effects of PPAR-? agonists on relapse, sensitization, conditioned place preference, withdrawal and drug intake, and effects of PPAR-? agonists on relapse, withdrawal and drug intake. Finally, studies that investigated the effects of PPAR agonists on neural pathways of addiction are reviewed. Taken together this preclinical data indicates that PPAR agonists are promising new medications for drug addiction treatment. PMID:23614675

Foll, Bernard Le; Ciano, Patricia Di; Panlilio, Leigh V.; Goldberg, Steven R.; Ciccocioppo, Roberto

2013-01-01

16

The Renoprotective Actions of Peroxisome Proliferator-Activated Receptors Agonists in Diabetes  

PubMed Central

Pharmaceutical agonists of peroxisome proliferator-activated receptors (PPARs) are widely used in the management of type 2 diabetes, chiefly as lipid-lowering agents and oral hypoglycaemic agents. Although most of the focus has been placed on their cardiovascular effects, both positive and negative, these agents also have significant renoprotective actions in the diabetic kidney. Over and above action on metabolic control and effects on blood pressure, PPAR agonists also appear to have independent effects on a number of critical pathways that are implicated in the development and progression of diabetic kidney disease, including oxidative stress, inflammation, hypertrophy, and podocyte function. This review will examine these direct and indirect actions of PPAR agonists in the diabetic kidney and explore recent findings of clinical trials of PPAR agonists in patients with diabetes. PMID:22448165

Thomas, M. C.; Jandeleit-Dahm, K. A.; Tikellis, C.

2012-01-01

17

Stimulation of innate immune cells by light-activated TLR7/8 agonists.  

PubMed

The innate immune response is controlled, in part, by the synergistic interaction of multiple Toll-like receptors (TLRs). This multi-receptor cooperation is responsible for the potent activity of many vaccines, but few tools have been developed to understand the spatio-temporal elements of TLR synergies. In this Communication, we present photo-controlled agonists of TLR7/8. By strategically protecting the active agonist moiety based on an agonist-bound crystal structure, TLR activity is suppressed and then regained upon exposure to light. We confirmed NF-?B production upon light exposure in a model macrophage cell line. Primary cell activity was confirmed by examining cytokine and cell surface marker production in bone-marrow-derived dendritic cells. Finally, we used light to activate dendritic cell sub-populations within a larger population. PMID:25029205

Ryu, Keun Ah; Stutts, Lalisa; Tom, Janine K; Mancini, Rock J; Esser-Kahn, Aaron P

2014-08-01

18

Cigarette smoke exposure inhibits contact hypersensitivity via the generation of platelet-activating factor agonists.  

PubMed

Previous studies have established that pro-oxidative stressors suppress host immunity because of their ability to generate oxidized lipids with platelet-activating factor receptor (PAF-R) agonist activity. Although exposure to the pro-oxidative stressor cigarette smoke (CS) is known to exert immunomodulatory effects, little is known regarding the role of PAF in these events. The current studies sought to determine the role of PAF-R signaling in CS-mediated immunomodulatory effects. We demonstrate that CS exposure induces the generation of a transient PAF-R agonistic activity in the blood of mice. CS exposure inhibits contact hypersensitivity in a PAF-R-dependent manner as PAF-R-deficient mice were resistant to these effects. Blocking PAF-R agonist production either by systemic antioxidants or treatment with serum PAF-acetyl hydrolase enzyme blocked both the CS-mediated generation of PAF-R agonists and PAF-R-dependent inhibition of contact hypersensitivity (CHS) reactions, indicating a role for oxidized glycerophosphocholines with PAF-R agonistic activity in this process. In addition, cyclooxygenase-2 inhibition did not block PAF-R agonist production but prevented CS-induced inhibition of CHS. This suggests that cyclooxygenase-2 acts downstream of the PAF-R in mediating CS-induced systemic immunosuppression. Moreover, CS exposure induced a significant increase in the expression of the regulatory T cell reporter gene in Foxp3(EGFP) mice but not in Foxp3(EGFP) mice on a PAF-R-deficient background. Finally, regulatory T cell depletion via anti-CD25 Abs blocked CS-mediated inhibition of CHS, indicating the potential involvement of regulatory T cells in CS-mediated systemic immunosuppression. These studies provide the first evidence, to our knowledge, that the pro-oxidative stressor CS can modulate cutaneous immunity via the generation of PAF-R agonists produced through lipid oxidation. PMID:23355733

Sahu, Ravi P; Petrache, Irina; Van Demark, Mary J; Rashid, Badri M; Ocana, Jesus A; Tang, Yuxuan; Yi, Qiaofang; Turner, Matthew J; Konger, Raymond L; Travers, Jeffrey B

2013-03-01

19

Evaluation of peroxisome proliferator-activated receptor agonists on interleukin-5-induced eosinophil differentiation.  

PubMed

Peroxisome proliferator-activated receptor (PPAR) agonists have been suggested as novel therapeutics for the treatment of inflammatory lung disease, such as allergic asthma. Treatment with PPAR agonists has been shown to inhibit airway eosinophilia in murine models of allergic asthma, which can occur through several mechanisms including attenuated generation of chemoattractants (e.g. eotaxin) and decreased eosinophil migrational responses. In addition, studies report that PPAR agonists can inhibit the differentiation of several cell types. To date, no studies have examined the effects of PPAR agonists on interleukin-5 (IL-5) -induced eosinophil differentiation from haemopoietic progenitor cells. Non-adherent mononuclear cells or CD34(+) cells isolated from the peripheral blood of allergic subjects were grown for 2 weeks in Methocult(®) cultures with IL-5 (10 ng/ml) and IL-3 (25 ng/ml) in the presence of 1-1000 nm PPAR? agonist (GW9578), PPAR?/? agonist (GW501516), PPAR? agonist (rosiglitazone) or diluent. The number of eosinophil/basophil colony-forming units (Eo/B CFU) was quantified by light microscopy. The signalling mechanism involved was assessed by phosphoflow. Blood-extracted CD34(+) cells cultured with IL-5 or IL-5 + IL-3 formed Eo/B CFU, which were significantly inhibited by rosiglitazone (100 nm, P < 0·01) but not GW9578 or GW501516. In addition, rosglitazone significantly inhibited IL-5-induced phosphorylation of extracellular signal-regulated kinase 1/2. We observed an inhibitory effect of rosiglitazone on eosinophil differentiation in vitro, mediated by attenuation of the extracellular signal-regulated kinase 1/2 signalling pathway. These findings indicate that the PPAR? agonist can attenuate tissue eosinophilia by interfering with local differentiative responses. PMID:24628018

Smith, Steven G; Hill, Mike; Oliveria, John-Paul; Watson, Brittany M; Baatjes, Adrian J; Dua, Benny; Howie, Karen; Campbell, Heather; Watson, Rick M; Sehmi, Roma; Gauvreau, Gail M

2014-07-01

20

Fibroblast Growth Factor Inducible (Fn14)-specific Antibodies Concomitantly Display Signaling Pathway-specific Agonistic and Antagonistic Activity*  

PubMed Central

The Fn14-specific monoclonal antibodies PDL192 and P4A8, which are under consideration in clinical trials, showed no agonistic activity with respect to IL8 production and cell death induction. However, oligomerization with protein G or binding to Fc? receptors converted both anti-Fn14 antibodies into potent agonists. TNF-like weak inducer of apoptosis (TWEAK), the ligand of Fn14, occurs naturally in two forms with partly different signaling capabilities, as a membrane-bound ligand and as a soluble trimeric molecule. Although membrane TWEAK strongly triggers all Fn14-associated pathways, soluble TWEAK predominately triggers the alternative nuclear factor ?B (NF?B) pathway and enhances TNF-induced cell death but has only a poor effect on the classical NF?B pathway and chemokine production. Thus, the oligomerized and Fc?R-bound anti-Fn14 mAbs mimicked the activity of membrane TWEAK. Notably, both anti-Fn14 antibodies significantly triggered p100 processing, the hallmark of the alternative NF?B pathway, and therefore resembled soluble TWEAK. In contrast to the latter, however, the anti-Fn14s showed no effect on TNF receptor 1-induced cell death and P4A8 even blocked the corresponding TWEAK response. Thus, we showed that Fn14 antibodies display an alternative NF?B pathway-specific agonistic activity but fail to phenocopy other activities of soluble TWEAK, whereas oligomerized or Fc?R-bound Fn14 antibodies fully mimic the activity of membrane TWEAK. In view of the trivalent nature of the TWEAK-Fn14 interaction, this suggests that the alternative NF?B pathway is uniquely responsive already to Fn14 dimerization enabling antibodies to elicit an unnatural response pattern distinct from that of the naturally occurring Fn14 ligands. PMID:23532848

Salzmann, Steffen; Seher, Axel; Trebing, Johannes; Weisenberger, Daniela; Rosenthal, Alevtina; Siegmund, Daniela; Wajant, Harald

2013-01-01

21

Protective effects of a peroxisome proliferator-activated receptor-h/y agonist in experimental autoimmune encephalomyelitis  

E-print Network

Protective effects of a peroxisome proliferator-activated receptor-h/y agonist in experimental Agonists of the peroxisome proliferator-activated receptor gamma (PPARg) exert anti-inflammatory and anti. Introduction Peroxisome Proliferator-Activated Receptors (PPARs) are nuclear hormone receptors. In response

Omiecinski, Curtis

22

alpha7 receptor-selective agonists and modes of alpha7 receptor activation.  

PubMed

The alpha7-selective agonists 3-(2, 4-dimethoxybenzylidene)-anabaseine (GTS-21), also known as DMXB, and 3-(4-hydroxy,2-methoxybenzylidene)anabaseine (4OH-GTS-21) produce a variety of behavioral and cytoprotective effects that may be related to the activation of either large transient currents at high concentrations or small sustained currents at lower agonist concentrations. We are using acutely dissociated hypothalamic neurons, which express a central nervous system (CNS) alpha7-type receptor, to test a model for the concentration-dependent desensitization of alpha7-mediated responses. Our results confirm that 4OH-GTS-21 is a potent activator of neuronal alpha7 nicotinic-acetylcholine receptor. The rapid application of agonist leads to a brief period of maximal receptor-activation followed by desensitization. Rise rates, decay rates, and the degree to which current was desensitized were all concentration-dependent. Following the initial peak response to a 300-microM 4OH-GTS-21 application, current is reduced to baseline values within about 100 ms. Application of 30 microM 4OH-GTS-21 produced both a transient peak current and a sustained current that decayed only slowly after the removal of agonist. In the case of a 300-microM 4OH-GTS-21 application, after agonist was removed, we saw a rebound response up to the level of the 30-microM sustained current. The data, therefore, suggest that a sufficient level of agonist occupation can be retained on the receptor to promote activation for up to several hundred milliseconds. PMID:10771012

Papke, R L; Meyer, E; Nutter, T; Uteshev, V V

2000-03-30

23

Nonsteroidal ecdysone agonists.  

PubMed

Nonsteroidal ecdysone agonists are novel compounds that have become attractive candidates not only as pest control agents in agriculture but also as tools for research. Their narrow spectrum of activity makes them relatively safe as pesticides, and their mode of action as ligands for gene expression has found application in gene therapy and inducing transgenic gene expression in plants. These diacylhydrazines (DAHs) are potent nonsteroidal ecdysone agonists, and four of them, tebufenozide, methoxyfenozide, chromafenozide, and halofenozide, have been developed as insecticides. Although these compounds are very toxic to insects, they are safe for mammals and are environmentally benign. Their action on insects is also selective, the first three are effective against Lepidoptera but weakly active or inactive on Diptera and Coleoptera. On the other hand, halofenozide is effective on Coleoptera but mildly active on Lepidoptera. Previous reviews on ecdysone agonists have concentrated on the biological response of some DAHs and their effects on pests. In this review, the chemistry, biological effects and their modes of action at the molecular level will be covered. In addition, a few studies on other nonsteroidal ecdysone agonists, such as 3,5-di-tert-butyl-4-hydroxy-N-iso-butylbenzamide, acylaminoketones, and benzoyl-1,2,3,4-tetrahydroquinolines, will be briefly reviewed. PMID:16399410

Nakagawa, Yoshiaki

2005-01-01

24

Platelet-activating Factor Receptor Agonists Mediate Xeroderma Pigmentosum A Photosensitivity*  

PubMed Central

To date, oxidized glycerophosphocholines (Ox-GPCs) with platelet-activating factor (PAF) activity produced non-enzymatically have not been definitively demonstrated to mediate any known disease processes. Here we provide evidence that these Ox-GPCs play a pivotal role in the photosensitivity associated with the deficiency of the DNA repair protein xeroderma pigmentosum type A (XPA). It should be noted that XPA-deficient cells are known to have decreased antioxidant defenses. These studies demonstrate that treatment of human XPA-deficient fibroblasts with the pro-oxidative stressor ultraviolet B (UVB) radiation resulted in increased reactive oxygen species and PAF receptor (PAF-R) agonistic activity in comparison with gene-corrected cells. The UVB irradiation-generated PAF-R agonists were inhibited by antioxidants. UVB irradiation of XPA-deficient (Xpa?/?) mice also resulted in increased PAF-R agonistic activity and skin inflammation in comparison with control mice. The increased UVB irradiation-mediated skin inflammation and TNF-? production in Xpa?/? mice were blocked by systemic antioxidants and by PAF-R antagonists. Structural characterization of PAF-R-stimulating activity in UVB-irradiated XPA-deficient fibroblasts using mass spectrometry revealed increased levels of sn-2 short-chain Ox-GPCs along with native PAF. These studies support a critical role for PAF-R agonistic Ox-GPCs in the pathophysiology of XPA photosensitivity. PMID:22303003

Yao, Yongxue; Harrison, Kathleen A.; Al-Hassani, Mohammed; Murphy, Robert C.; Rezania, Samin; Konger, Raymond L.; Travers, Jeffrey B.

2012-01-01

25

Peroxisome Proliferator-Activated Receptor Agonists: Do They Increase Cardiovascular Risk?  

PubMed Central

Cardiovascular disease is a major cause of morbidity and mortality among people with type 2 diabetes mellitus. The peroxisome proliferator-activated receptor (PPAR) agonists have a significant role on glucose and fat metabolism. Thiazolidinediones (TZDs) are predominantly PPAR? agonists, and their primary benefit appears to be the prevention of diabetic complications by improving glycemic control and lipid profile. Recently, the cardiovascular safety of rosiglitazone was brought to center stage following meta analyses and the interim analysis of the RECORD trial. Current evidence points to rosiglitazone having a greater risk of myocardial ischemic events than placebo, metformin, or sulfonylureas. This review article discusses the mechanism of action of PPAR agonists and correlates it with clinical and laboratory outcomes in the published literature. In addition, this review article attempts to discuss some of the molecular mechanisms regarding the association between TZDs therapy and the nontraditional cardiovascular risks. PMID:19696948

Aljada, Ahmad; Shah, Kshitij Ashwin; Mousa, Shaker A.

2009-01-01

26

Estrogenic Agonist Activity of ICI 182,780 (Faslodex) in Hippocampal Neurons: Implications for Basic Science  

E-print Network

to estrogen therapy for the prevention of post- menopausal cognitive decline and late-onset Alzheimer's dis of the development of resistance to TMX therapy for the treat- ment of estrogen-dependent breast cancers (Howell etEstrogenic Agonist Activity of ICI 182,780 (Faslodex) in Hippocampal Neurons: Implications

Brinton, Roberta Diaz

27

Effects of peroxisome proliferator-activated receptor  \\/  agonists on HDL-cholesterol in vervet monkeys  

Microsoft Academic Search

The objective of this study was to demonstrate the efficacy of a novel peroxisome proliferator-activated re- ceptor (PPAR) agonist and known PPARand PPARago- nists to increase HDL-cholesterol (HDL-C) in the St. Kitts vervet, a nonhuman primate model of atherosclerosis. Four groups (n ? 6) were studied and each group was assigned one of the following \\

Jeanne M. Wallace; Margrit Schwarz; Peter Coward; Jonathan Houze; Janet K. Sawyer; Kathryn L. Kelley; Anne Chai; Lawrence L. Rudel

2005-01-01

28

Peroxisome Proliferator-Activated Receptor Gamma Agonists in Kidney Disease – Future Promise, Present Fears  

Microsoft Academic Search

The peroxisome proliferator-activated receptor superfamily (PPARs) comprises a class of nuclear receptors with significant effects in regulating multiple cellular pathways. Much research and clinical interest has surrounded the PPAR-? isoform because of its key role in the transcriptional regulation of metabolic pathways and the efficacy of thiazolidinediones, the most clinically used PPAR-? agonist, in the management of type 2 diabetes

Zhiguo Mao; Albert C. M. Ong

2009-01-01

29

Changes in agonist EMG activation level during MVC cannot explain early strength improvement  

Microsoft Academic Search

A substantial gain in strength is often observed in the early phase of resistance training. The aim of this study was to address whether improved strength in the early phase of resistance training, can be attributed to increased activation, or to intra-muscular changes of the agonist muscle during maximal isometric torque production. Fourteen male subjects trained maximal isometric dorsiflexion during

Andreas Holtermann; Karin Roeleveld; Beatrix Vereijken; Gertjan Ettema

2005-01-01

30

Differential gene expression in mouse primary hepatocytes exposed to the peroxisome proliferator-activated receptor ? agonists  

PubMed Central

Background Fibrates are a unique hypolipidemic drugs that lower plasma triglyceride and cholesterol levels through their action as peroxisome proliferator-activated receptor alpha (PPAR?) agonists. The activation of PPAR? leads to a cascade of events that result in the pharmacological (hypolipidemic) and adverse (carcinogenic) effects in rodent liver. Results To understand the molecular mechanisms responsible for the pleiotropic effects of PPAR? agonists, we treated mouse primary hepatocytes with three PPAR? agonists (bezafibrate, fenofibrate, and WY-14,643) at multiple concentrations (0, 10, 30, and 100 ?M) for 24 hours. When primary hepatocytes were exposed to these agents, transactivation of PPAR? was elevated as measured by luciferase assay. Global gene expression profiles in response to PPAR? agonists were obtained by microarray analysis. Among differentially expressed genes (DEGs), there were 4, 8, and 21 genes commonly regulated by bezafibrate, fenofibrate, and WY-14,643 treatments across 3 doses, respectively, in a dose-dependent manner. Treatments with 100 ?M of bezafibrate, fenofibrate, and WY-14,643 resulted in 151, 149, and 145 genes altered, respectively. Among them, 121 genes were commonly regulated by at least two drugs. Many genes are involved in fatty acid metabolism including oxidative reaction. Some of the gene changes were associated with production of reactive oxygen species, cell proliferation of peroxisomes, and hepatic disorders. In addition, 11 genes related to the development of liver cancer were observed. Conclusion Our results suggest that treatment of PPAR? agonists results in the production of oxidative stress and increased peroxisome proliferation, thus providing a better understanding of mechanisms underlying PPAR? agonist-induced hepatic disorders and hepatocarcinomas. PMID:17118139

Guo, Lei; Fang, Hong; Collins, Jim; Fan, Xiao-hui; Dial, Stacey; Wong, Alex; Mehta, Kshama; Blann, Ernice; Shi, Leming; Tong, Weida; Dragan, Yvonne P

2006-01-01

31

Natural product agonists of peroxisome proliferator-activated receptor gamma (PPAR?): a review  

PubMed Central

Agonists of the nuclear receptor PPAR? are therapeutically used to combat hyperglycaemia associated with the metabolic syndrome and type 2 diabetes. In spite of being effective in normalization of blood glucose levels, the currently used PPAR? agonists from the thiazolidinedione type have serious side effects, making the discovery of novel ligands highly relevant. Natural products have proven historically to be a promising pool of structures for drug discovery, and a significant research effort has recently been undertaken to explore the PPAR?-activating potential of a wide range of natural products originating from traditionally used medicinal plants or dietary sources. The majority of identified compounds are selective PPAR? modulators (SPPARMs), transactivating the expression of PPAR?-dependent reporter genes as partial agonists. Those natural PPAR? ligands have different binding modes to the receptor in comparison to the full thiazolidinedione agonists, and on some occasions activate in addition PPAR? (e.g. genistein, biochanin A, sargaquinoic acid, sargahydroquinoic acid, resveratrol, amorphastilbol) or the PPAR?-dimer partner retinoid X receptor (RXR; e.g. the neolignans magnolol and honokiol). A number of in vivo studies suggest that some of the natural product activators of PPAR? (e.g. honokiol, amorfrutin 1, amorfrutin B, amorphastilbol) improve metabolic parameters in diabetic animal models, partly with reduced side effects in comparison to full thiazolidinedione agonists. The bioactivity pattern as well as the dietary use of several of the identified active compounds and plant extracts warrants future research regarding their therapeutic potential and the possibility to modulate PPAR? activation by dietary interventions or food supplements. PMID:25083916

Wang, Limei; Waltenberger, Birgit; Pferschy-Wenzig, Eva-Maria; Blunder, Martina; Liu, Xin; Malainer, Clemens; Blazevic, Tina; Schwaiger, Stefan; Rollinger, Judith M.; Heiss, Elke H.; Schuster, Daniela; Kopp, Brigitte; Bauer, Rudolf; Stuppner, Hermann; Dirsch, Verena M.; Atanasov, Atanas G.

2014-01-01

32

Recovery of brain biomarkers following peroxisome proliferator-activated receptor agonist neuroprotective treatment before ischemic stroke  

PubMed Central

Background Lipid lowering agent such as agonists of peroxisome proliferator-activated receptors (PPAR) are suggested as neuroprotective agents and may protect from the sequelae of brain ischemic stroke. Although the demonstration is not clearly established in human, the underlying molecular mechanism may be of interest for future therapeutic purposes. To this end, we have used our well established rodent model of ischemia-reperfusion pre-treated or not with fenofibrate or atorvastatin and performed a differential proteomics analyses of the brain and analysed the protein markers which levels returned to “normal” following pre-treatments with PPAR? agonists. Results In order to identify potential therapeutic targets positively modulated by pre-treatment with the PPAR? agonists, two-dimensional gel electrophoresis proteome profiles between control, ischemia-reperfusion and pre-treated or not, were compared. The polypeptide which expression was altered following ischemia – reperfusion but whose levels remain unchanged after pre-treatment were characterized by mass spectrometry and further investigated by Western-blotting and immunohistochemistry. A series of 28 polypeptides were characterized among which the protein disulfide isomerase reduction – a protein instrumental to the unfolded protein response system - was shown to be reduced following PPAR? agonists treatment while it was strongly increased in ischemia-reperfusion. Conclusions Pre-treatment with PPAR? agonist or atorvastatin show potential neuroprotective effects by inhibiting the PDI overexpression in conjunction with the preservation of other neuronal markers, several of which are associated with the regulation of protein homeostasis, signal transduction and maintenance of synaptic plasticity. This proteomic study therefore suggests that neuroprotective effect of PPAR? agonists supposes the preservation of the expression of several proteins essential for the maintenance of protein homeostasis not necessarily directly linked to PPAR? known-regulated targets. PMID:24944524

2014-01-01

33

?-Mangostin from Garcinia mangostana pericarps as a dual agonist that activates Both PPAR? and PPAR?.  

PubMed

We tested the peroxisome proliferator-activated receptor (PPAR)? agonistic activity of a Garcinia mangostana pericarp extract to develop a treatment for the metabolic syndrome, and demonstrated ?-mangostin to be an active compound on the basis of a luciferase reporter gene assay. ?-Mangostin induced the expression of the uncoupling protein-3 (UCP-3) gene which is related to energy expenditure and fat metabolism in L6 cells. We showed that ?-mangostin is a dual agonist that activates both PPAR? and PPAR?. ?-Mangostin also induced the expression of acyl-CoA synthase and carnitine palmitoyl-transferase 1A genes in HepG2 cells. These results suggest the potential of ?-mangostin as a preventive agent of the metabolic syndrome. PMID:24317060

Matsuura, Nobuyasu; Gamo, Kanae; Miyachi, Hiroyuki; Iinuma, Munekazu; Kawada, Teruo; Takahashi, Nobuyuki; Akao, Yukihiro; Tosa, Hideki

2013-01-01

34

Cytokine receptor dimerization and activation: prospects for small molecule agonists  

Microsoft Academic Search

Ligand-induced dimerization of cell surface receptors has emerged as a general mechanism for the initiation of signal transduction. A number of therapeutically important receptor families are believed to be activated by this process. Recently available structural information, particularly for the erythropoietin receptor, has provided insight into the mechanism of receptor activation. These findings have also revealed important constraints on the

Dale L. Boger; Joel Goldberg

2001-01-01

35

Activity of mu- and delta-opioid agonists in vas deferens from mice deficient in MOR gene  

PubMed Central

Mice lacking the mu-opioid receptor have been recently generated. Centrally mediated responses of mu-opioid agonists are suppressed whereas some of the delta-opioid responses are preserved in these mutant mice. The vas deferens bioassay has been used in this study to investigate the functional activity at a peripheral level of mu- and delta-opioid agonists in mice lacking mu-opioid receptors. The different mu-opioid agonists evaluated, morphine, DAMGO, dermorphin and [Lys7]-dermorphin produced an inhibitory response in vas deferens from wild-type mice but had no relevant activity on vas deferens from mutant mice. The selective delta-opioid agonists DPDPE, BUBU, deltorphin I, deltorphin II and [D-Met2]-deltorphin induced inhibitory effects in vas deferens from both wild-type and mutant mice. However, the biological activities of these ligands were slightly reduced in preparations from mutant mice. The inhibitory responses of all these delta-opioid agonists were prevented by the administration of the selective delta-opioid antagonist naltrindole. These data indicate that delta-opioid agonists, but not mu-opioid agonists, are biologically active in vas deferens from mice lacking mu-opioid receptors. The decreased response of delta-agonists in mutant mice suggests that some cooperativity may exist between mu- and delta-opioid receptors in these vas deferens preparations. PMID:11264242

Maldonado, Rafael; Severini, Cintia; Matthes, Hans W D; Kieffer, Brigitte L; Melchiorri, Pietro; Negri, Lucia

2001-01-01

36

Muscle Activation Is Different When the Same Muscle Acts as an Agonist or an Antagonist During Voluntary Movement  

Microsoft Academic Search

During movement, the intrinsic muscle force-velocity property decreases the net force for the shortening muscle (agonist) and increases it for the lengthening muscle (antagonist). The authors present a quantitative analysis of the effect of that muscle property on activation and force output of the same muscle acting as agonist and antagonist in fast and medium speed goaloriented movements. They compared

Mark B. Shapiro; Janey Prodoehl; Daniel M. Corcos; Gerald L. Gottlieb

2005-01-01

37

Nalmefene induced elevation in serum prolactin in normal human volunteers: partial kappa opioid agonist activity?  

PubMed

In humans, mu- and kappa-opioid receptor agonists lower tuberoinfundibular dopamine, which tonically inhibits prolactin release. Serum prolactin is, therefore, a useful biomarker for tuberoinfundibular dopamine. The current study evaluated the unexpected finding that the relative mu- and kappa-opioid receptor selective antagonist nalmefene increases serum prolactin, indicating possible kappa-opioid receptor agonist activity. In all, 33 healthy human volunteers (14 female) with no history of psychiatric or substance use disorders received placebo, nalmefene 3 mg, and nalmefene 10 mg in a double-blind manner. Drugs were administered between 0900 and 1000 on separate days via 2-min intravenous infusion. Serial blood specimens were analyzed for serum levels of prolactin. Additional in vitro studies of nalmefene binding to cloned human kappa-opioid receptors transfected into Chinese hamster ovary cells were performed. Compared to placebo, both doses of nalmefene caused significant elevations in serum prolactin (p<0.002 for nalmefene 3 mg and p<0.0005 for nalmefene 10 mg). There was no difference in prolactin response between the 3 and 10 mg doses. Binding assays confirmed nalmefene's affinity at kappa-opioid receptors and antagonism of mu-opioid receptors. [(35)S]GTPgammaS binding studies demonstrated that nalmefene is a full antagonist at mu-opioid receptors and has partial agonist properties at kappa-opioid receptors. Elevations in serum prolactin following nalmefene are consistent with this partial agonist effect at kappa-opioid receptors. As kappa-opioid receptor activation can lower dopamine in brain regions important to the persistence of alcohol and cocaine dependence, the partial kappa agonist effect of nalmefene may enhance its therapeutic efficacy in selected addictive diseases. PMID:15988468

Bart, Gavin; Schluger, James H; Borg, Lisa; Ho, Ann; Bidlack, Jean M; Kreek, Mary Jeanne

2005-12-01

38

Peroxisome proliferator-activated receptor agonists modulate neuropathic pain: a link to chemokines?  

PubMed

Chronic pain presents a widespread and intractable medical problem. While numerous pharmaceuticals are used to treat chronic pain, drugs that are safe for extended use and highly effective at treating the most severe pain do not yet exist. Chronic pain resulting from nervous system injury (neuropathic pain) is common in conditions ranging from multiple sclerosis to HIV-1 infection to type II diabetes. Inflammation caused by neuropathy is believed to contribute to the generation and maintenance of neuropathic pain. Chemokines are key inflammatory mediators, several of which (MCP-1, RANTES, MIP-1?, fractalkine, SDF-1 among others) have been linked to chronic, neuropathic pain in both human conditions and animal models. The important roles chemokines play in inflammation and pain make them an attractive therapeutic target. Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear receptors known for their roles in metabolism. Recent research has revealed that PPARs also play a role in inflammatory gene repression. PPAR agonists have wide-ranging effects including inhibition of chemokine expression and pain behavior reduction in animal models. Experimental evidence suggests a connection between the pain ameliorating effects of PPAR agonists and suppression of inflammatory gene expression, including chemokines. In early clinical research, one PPAR? agonist, palmitoylethanolamide (PEA), shows promise in relieving chronic pain. If this link can be better established, PPAR agonists may represent a new drug therapy for neuropathic pain. PMID:25191225

Freitag, Caroline M; Miller, Richard J

2014-01-01

39

Structure-activity relationships of vanilloid receptor agonists for arteriolar TRPV1  

PubMed Central

BACKGROUND AND PURPOSE The transient receptor potential vanilloid 1 (TRPV1) plays a role in the activation of sensory neurons by various painful stimuli and is a therapeutic target. However, functional TRPV1 that affect microvascular diameter are also expressed in peripheral arteries and we attempted to characterize this receptor. EXPERIMENTAL APPROACH Sensory TRPV1 activation was measured in rats by use of an eye wiping assay. Arteriolar TRPV1-mediated smooth muscle specific responses (arteriolar diameter, changes in intracellular Ca2+) were determined in isolated, pressurized skeletal muscle arterioles obtained from the rat and wild-type or TRPV1?/? mice and in canine isolated smooth muscle cells. The vascular pharmacology of the TRPV1 agonists (potency, efficacy, kinetics of action and receptor desensitization) was determined in rat isolated skeletal muscle arteries. KEY RESULTS Capsaicin evoked a constrictor response in isolated arteries similar to that mediated by noradrenaline, this was absent in arteries from TRPV1 knockout mice and competitively inhibited by TRPV1 antagonist AMG9810. Capsaicin increased intracellular Ca2+ in the arteriolar wall and in isolated smooth muscle cells. The TRPV1 agonists evoked similar vascular constrictions (MSK-195 and JYL-79) or were without effect (resiniferatoxin and JYL-273), although all increased the number of responses (sensory activation) in the eye wiping assay. Maximal doses of all agonists induced complete desensitization (tachyphylaxis) of arteriolar TRPV1 (with the exception of capsaicin). Responses to the partial agonist JYL-1511 suggested 10% TRPV1 activation is sufficient to evoke vascular tachyphylaxis without sensory activation. CONCLUSIONS AND IMPLICATIONS Arteriolar TRPV1 have different pharmacological properties from those located on sensory neurons in the rat. PMID:21883148

Czikora, Á; Lizanecz, E; Bakó, P; Rutkai, I; Ruzsnavszky, F; Magyar, J; Pórszász, R; Kark, T; Facskó, A; Papp, Z; Édes, I; Tóth, A

2012-01-01

40

Isoflavone agonists of IRF-3 dependent signaling have antiviral activity against RNA viruses.  

PubMed

There is a growing need for novel antiviral therapies that are broad spectrum, effective, and not subject to resistance due to viral mutations. Using high-throughput screening methods, including computational docking studies and an interferon-stimulated gene 54 (ISG54)-luciferase reporter assay, we identified a class of isoflavone compounds that act as specific agonists of innate immune signaling pathways and cause activation of the interferon regulatory factor (IRF-3) transcription factor. The isoflavone compounds activated the ISG54 promoter, mediated nuclear translocation of IRF-3, and displayed highly potent activity against hepatitis C virus (HCV) and influenza virus. Additionally, these agonists efficiently activated IRF-3 in the presence of the HCV protease NS3-4A, which is known to blunt the host immune response. Furthermore, genomic studies showed that discrete innate immune pathways centered on IRF signaling were regulated following agonist treatment without causing global changes in host gene expression. Following treatment, the expression of only 64 cellular genes was significantly induced. This report provides the first evidence that innate immune pathways dependent on IRF-3 can be successfully targeted by small-molecule drugs for the development of novel broad-spectrum antiviral compounds. PMID:22532686

Bedard, Kristin M; Wang, Myra L; Proll, Sean C; Loo, Yueh-Ming; Katze, Michael G; Gale, Michael; Iadonato, Shawn P

2012-07-01

41

Isoflavone Agonists of IRF-3 Dependent Signaling Have Antiviral Activity against RNA Viruses  

PubMed Central

There is a growing need for novel antiviral therapies that are broad spectrum, effective, and not subject to resistance due to viral mutations. Using high-throughput screening methods, including computational docking studies and an interferon-stimulated gene 54 (ISG54)-luciferase reporter assay, we identified a class of isoflavone compounds that act as specific agonists of innate immune signaling pathways and cause activation of the interferon regulatory factor (IRF-3) transcription factor. The isoflavone compounds activated the ISG54 promoter, mediated nuclear translocation of IRF-3, and displayed highly potent activity against hepatitis C virus (HCV) and influenza virus. Additionally, these agonists efficiently activated IRF-3 in the presence of the HCV protease NS3-4A, which is known to blunt the host immune response. Furthermore, genomic studies showed that discrete innate immune pathways centered on IRF signaling were regulated following agonist treatment without causing global changes in host gene expression. Following treatment, the expression of only 64 cellular genes was significantly induced. This report provides the first evidence that innate immune pathways dependent on IRF-3 can be successfully targeted by small-molecule drugs for the development of novel broad-spectrum antiviral compounds. PMID:22532686

Wang, Myra L.; Proll, Sean C.; Loo, Yueh-Ming; Katze, Michael G.; Gale, Michael; Iadonato, Shawn P.

2012-01-01

42

Liver X Receptor and Peroxisome Proliferator-Activated Receptor Agonist from Cornus alternifolia  

PubMed Central

Background Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptors superfamily and are transcription factors activated by specific ligands. Liver X receptors (LXR) belong to the nuclear hormone receptors and have been shown to play an important role in cholesterol homeostasis. From the previous screening of several medicinal plants for potential partial PPAR? agonists, the extracts of Cornus alternifolia were found to exhibit promising bioactivity. In this paper, we report the isolation and structural elucidation of four new compounds and their potential as ligands for PPAR. Methods The new compounds were extracted from the leaves of Cornus alternifolia and fractionated by high-performance liquid chromatography. Their structures were elucidated on the basis of spectroscopic evidence and analysis of their hydrolysis products. Results Three new iridoid glycosides including an iridolactone, alternosides A-C (1–3), a new megastigmane glycoside, cornalternoside (4) and 10 known compounds, were obtained from the leaves of Cornus alternifolia. Kaempferol-3-O-?-glucopyranoside (5) exhibited potent agonistic activities for PPAR?, PPAR? and LXR with EC50 values of 0.62, 3.0 and 1.8 ? M, respectively. Conclusions We isolated four new and ten known compounds from Cornus alternifolia, and one known compound showed agonistic activities for PPAR?, PPAR? and LXR. General significance Compound 1 is the first example of a naturally occurring iridoid glycoside containing a ?-glucopyranoside moiety at C-6. PMID:22353334

He, Yang-Qing; Ma, Guo-Yi; Peng, Jiang-nan; Ma, Zhan-Ying; Hamann, Mark T.

2012-01-01

43

Modeling active electrolocation in weakly electric fish  

E-print Network

In this paper, we provide a mathematical model for the electrolocation in weakly electric fishes. We first investigate the forward complex conductivity problem and derive the approximate boundary conditions on the skin of the fish. Then we provide a dipole approximation for small targets away from the fish. Based on this approximation, we obtain a non-iterative location search algorithm using multi-frequency measurements. We present numerical experiments to illustrate the performance and the stability of the proposed multi-frequency location search algorithm. Finally, in the case of disk- and ellipse-shaped targets, we provide a method to reconstruct separately the conductivity, the permittivity, and the size of the targets from multi-frequency measurements.

Habib Ammari; Thomas Boulier; Josselin Garnier

2012-03-05

44

Synthesis and activity of 4,5-diarylimidazoles as human CB1 receptor inverse agonists  

Microsoft Academic Search

Structure–activity relationship studies directed toward the optimization of 4,5-diarylimidazole-2-carboxamide analogs as human CB1 receptor inverse agonists resulted in the discovery of the two amide derivatives 24a and b (hCB1 IC50=6.1 and 4.0nM) which also demonstrated efficacy in overnight feeding studies in the rat for reduction in both food intake and overall body weight.

Christopher W. Plummer; Paul E. Finke; Sander G. Mills; Junying Wang; Xinchun Tong; George A. Doss; Tung M. Fong; Julie Z. Lao; Marie-Therese Schaeffer; Jing Chen; Chun-Pyn Shen; D. Sloan Stribling; Alison M. Strack

2005-01-01

45

Distinct indirect pathways govern human NK-cell activation by TLR-7 and TLR-8 agonists  

Microsoft Academic Search

NK cells limit the emergence of cancers and viral infections by surveillance of 'missing-self' and 'induced-self' ligands, and by direct recognition of pathogen-associated molecules. We examined individual roles for Toll-like receptors (TLRs)-7 and -8 in human NK-cell activation using synthetic, small molecule agonists of either TLR-7 (imiquimod and 3M-001), TLR-8 (3M-002) or both TLR-7\\/8 (3M-003 and R-848) for comparison with

Kevin S. Gorski; Emily L. Waller; Jacqueline Bjornton-Severson; John A. Hanten; Christie L. Riter; William C. Kieper; Keith B. Gorden; Jeffrey S. Miller; John P. Vasilakos; Mark A. Tomai; Sefik S. Alkan

2006-01-01

46

Direct Assessment of Cumulative Aryl Hydrocarbon Receptor Agonist Activity in Sera from Experimentally Exposed Mice and Environmentally Exposed Humans  

PubMed Central

Background Aryl hydrocarbon receptor (AhR) ligands adversely affect many biological processes. However, assessment of the significance of human exposures is hampered by an incomplete understanding of how complex mixtures affect AhR activation/inactivation. Objectives These studies used biological readouts to provide a broader context for estimating human risk than that obtained with serum extraction and gas chromatography/mass spectroscopy (GC/MS)-based assays alone. Methods AhR agonist activity was quantified in sera from dioxin-treated mice, commercial human sources, and polychlorinated biphenyl (PCB)–exposed Faroe Islanders using an AhR-driven reporter cell line. To validate relationships between serum AhR agonist levels and biological outcomes, AhR agonist activity in mouse sera correlated with toxic end points. AhR agonist activity in unmanipulated (“neat”) human sera was compared with these biologically relevant doses and with GC/MS-assayed PCB levels. Results Mouse serum AhR agonist activity correlated with injected dioxin dose, thymic atrophy, and heptomegaly, validating the use of neat serum to assess AhR agonist activity. AhR agonist activity in sera from Faroe Islanders varied widely, was associated with the frequency of recent pilot whale dinners, but did not correlate with levels of PCBs quantified by GC/MS. Surprisingly, significant “baseline” AhR activity was found in commercial human sera. Conclusions An AhR reporter assay revealed cumulative levels of AhR activation potential in neat serum, whereas extraction may preclude detection of important non-dioxin-like biological activity. Significant levels of AhR agonist activity in commercial sera and in Faroe Islander sera, compared with that from experimentally exposed mice, suggest human exposures that are biologically relevant in both populations. PMID:20435556

Schlezinger, Jennifer J.; Bernard, Pamela L.; Haas, Amelia; Grandjean, Philippe; Weihe, Pal; Sherr, David H.

2010-01-01

47

Antitussive activity of sigma-1 receptor agonists in the guinea-pig.  

PubMed

1. Current antitussive medications have limited efficacy and often contain the opiate-like agent dextromethorphan (DEX). The mechanism whereby DEX inhibits cough is ill defined. DEX displays affinity at both NMDA and sigma receptors, suggesting that the antitussive activity may involve central or peripheral activity at either of these receptors. This study examined and compared the antitussive activity of DEX and various putative sigma receptor agonists in the guinea-pig citric-acid cough model. 2. Intraperitoneal (i.p.) administration of DEX (30 mg kg(-1)) and the sigma-1 agonists SKF-10,047 (1-5 mg kg(-1)), Pre-084 (5 mg kg(-1)), and carbetapentane (1-5 mg kg(-1)) inhibited citric-acid-induced cough in guinea-pigs. Intraperitoneal administration of a sigma-1 antagonist, BD 1047 (1-5 mg kg(-1)), reversed the inhibition of cough elicited by SKF-10,047. In addition, two structurally dissimilar sigma agonists SKF-10,047 (1 mg ml(-1)) and Pre-084 (1 mg ml(-1)) inhibited cough when administered by aerosol. 3. Aerosolized BD 1047 (1 mg ml(-1), 30 min) prevented the antitussive action of SKF-10,047 (5 mg kg(-1)) or DEX (30 mg kg(-1)) given by i.p. administration and, likewise, i.p. administration of BD 1047 (5 mg kg(-1)) prevented the antitussive action of SKF-10,047 given by aerosol (1 mg ml(-1)). 4. These results therefore support the argument that antitussive effects of DEX may be mediated via sigma receptors, since both systemic and aerosol administration of sigma-1 receptor agonists inhibit citric-acid-induced cough in guinea-pigs. While significant systemic exposure is possible with aerosol administration, the very low doses administered (estimated <0.3 mg kg(-1)) suggest that there may be a peripheral component to the antitussive effect. PMID:14691051

Brown, Claire; Fezoui, Malika; Selig, William M; Schwartz, Carl E; Ellis, James L

2004-01-01

48

Design, Synthesis, and Functional Activity of Labeled CD1d Glycolipid Agonists  

PubMed Central

Invariant natural killer T cells (iNKT cells) are restricted by CD1d molecules and activated upon CD1d-mediated presentation of glycolipids to T cell receptors (TCRs) located on the surface of the cell. Because the cytokine response profile is governed by the structure of the glycolipid, we sought a method for labeling various glycolipids to study their in vivo behavior. The prototypical CD1d agonist, ?-galactosyl ceramide (?-GalCer) 1, instigates a powerful immune response and the generation of a wide range of cytokines when it is presented to iNKT cell TCRs by CD1d molecules. Analysis of crystal structures of the TCR??-GalCer–CD1d ternary complex identified the ?-methylene unit in the fatty acid side chain, and more specifically the pro-S hydrogen at this position, as a site for incorporating a label. We postulated that modifying the glycolipid in this way would exert a minimal impact on the TCR–glycolipid–CD1d ternary complex, allowing the labeled molecule to function as a good mimic for the CD1d agonist under investigation. To test this hypothesis, the synthesis of a biotinylated version of the CD1d agonist threitol ceramide (ThrCer) was targeted. Both diastereoisomers, epimeric at the label tethering site, were prepared, and functional experiments confirmed the importance of substituting the pro-S, and not the pro-R, hydrogen with the label for optimal activity. Significantly, functional experiments revealed that biotinylated ThrCer (S)-10 displayed behavior comparable to that of ThrCer 5 itself and also confirmed that the biotin residue is available for streptavidin and antibiotin antibody recognition. A second CD1d agonist, namely ?-GalCer C20:2 4, was modified in a similar way, this time with a fluorescent label. The labeled ?-GalCer C20:2 analogue (11) again displayed functional behavior comparable to that of its unlabeled substrate, supporting the notion that the ?-methylene unit in the fatty acid amide chain should be a suitable site for attaching a label to a range of CD1d agonists. The flexibility of the synthetic strategy, and late-stage incorporation of the label, opens up the possibility of using this labeling approach to study the in vivo behavior of a wide range of CD1d agonists. PMID:23458425

2013-01-01

49

Anti-hyperglycemic activity of a TGR5 agonist isolated from Olea europaea.  

PubMed

Olive tree (Olea europeaea) leaves are well known for their effect on metabolism in particular as a traditional anti-diabetic and anti-hypertensive herbal drug. These properties are until now only attributed to oleuropein, the major secoiridoid of olive leaves. Here we describe the isolation and the identification of another constituent implicated in the anti-diabetic effect of this plant, i.e. oleanolic acid. We show that this triterpene is an agonist for TGR5, a member of G-protein coupled receptor activated by bile acids and which mediates some of their various cellular and physiological effect. Oleanolic acid lowers serum glucose and insulin levels in mice fed with a high fat diet and it enhances glucose tolerance. Our data suggest that both oleuropein and oleanolic acid are involved in the anti-diabetic effect of olive leaves and further emphasize the potential role of TGR5 agonists to improve metabolic disorders. PMID:17825251

Sato, Hiroyuki; Genet, Cédric; Strehle, Axelle; Thomas, Charles; Lobstein, Annelise; Wagner, Alain; Mioskowski, Charles; Auwerx, Johan; Saladin, Régis

2007-11-01

50

Peroxisome proliferator-activated receptor-? agonist pioglitazone suppresses experimental autoimmune uveitis.  

PubMed

Peroxisome proliferator-activated receptor (PPAR)-? agonists are clinically used as anti-diabetes agents. Recent research has discovered that an anti-inflammatory effect of PPAR agonist may have the potential to treat autoimmune disease. In the present study, we investigated the anti-inflammatory effects of PPAR-? agonist, pioglitazone, on murine model of endogenous uveitis. Experimental autoimmune uveoretinitis (EAU) was induced by immunizing C57BL/6 mice with human interphotoreceptor retinoid binding protein-derived peptide (1-20). Pioglitazone or vehicle was injected intravenously from day -1 (whole phase treatment) or day 8 (effector phase study) until day 20. Severity of EAU was assessed clinically and pathologically on day 21. Immunological status was assessed by measuring intraocular inflammatory factors, and activation and regulatory markers of CD4(+) T cells in draining lymph nodes (LNs). Treatment with pioglitazone suppressed both whole-phase and effector-phase of EAU. In effector-phase treatment, intraocular concentrations of TNF-? and IL-6 were significantly suppressed, and CD4(+)Foxp3(+) regulatory T cells and CD4(+)CD62L(high) naïve T cells increased in draining LNs, although there were no differences in CD4(+)CD44(high) effector T cells and IL-17 producing CD4(+) T cells between pioglitazone- and vehicle-treated mice. Administration of pioglitazone before and after the onset of EAU significantly reduced disease severity. The present results suggest that pioglitazone may be a novel therapeutic agent for endogenous uveitis. PMID:24107513

Okunuki, Yoko; Usui, Yoshihiko; Nakagawa, Hayate; Tajima, Kazuki; Matsuda, Ryusaku; Ueda, Shunichiro; Hattori, Takaaki; Kezuka, Takeshi; Goto, Hiroshi

2013-11-01

51

Agonist activity of LSD and lisuride at cloned 5HT2A and 5HT2C receptors  

Microsoft Academic Search

Evidence from studies with phenylisopropylamine hallucinogens indicates that the 5HT2A receptor is the likely target for the initiation of events leading to hallucinogenic activity associated with LSD?and related\\u000a drugs. Recently, lisuride (a purported non-hallucinogenic congener of LSD) was reported to be a potent antagonist at the 5HT2C receptor and an agonist at the 5HT2A receptor. LSD exhibited agonist activity at

Christina T. Egan; Katharine Herrick-Davis; Keith Miller; Richard A. Glennon; M. Teitler

1998-01-01

52

Airway peroxidases catalyze nitration of the {beta}2-agonist salbutamol and decrease its pharmacological activity.  

PubMed

?(2)-agonists are the most effective bronchodilators for the rapid relief of asthma symptoms, but for unclear reasons, their effectiveness may be decreased during severe exacerbations. Because peroxidase activity and nitrogen oxides are increased in the asthmatic airway, we examined whether salbutamol, a clinically important ?(2)-agonist, is subject to potentially inactivating nitration. When salbutamol was exposed to myeloperoxidase, eosinophil peroxidase or lactoperoxidase in the presence of hydrogen peroxide (H(2)O(2)) and nitrite (NO(2)(-)), both absorption spectroscopy and mass spectrometry indicated formation of a new metabolite with features expected for the nitrated drug. The new metabolites showed an absorption maximum at 410 nm and pK(a) of 6.6 of the phenolic hydroxyl group. In addition to nitrosalbutamol (m/z 285.14), a salbutamol-derived nitrophenol, formed by elimination of the formaldehyde group, was detected (m/z 255.13) by mass spectrometry. It is noteworthy that the latter metabolite was detected in exhaled breath condensates of asthma patients receiving salbutamol but not in unexposed control subjects, indicating the potential for ?(2)-agonist nitration to occur in the inflamed airway in vivo. Salbutamol nitration was inhibited in vitro by ascorbate, thiocyanate, and the pharmacological agents methimazole and dapsone. The efficacy of inhibition depended on the nitrating system, with the lactoperoxidase/H(2)O(2)/NO(2)(-) being the most affected. Functionally, nitrated salbutamol showed decreased affinity for ?(2)-adrenergic receptors and impaired cAMP synthesis in airway smooth muscle cells compared with the native drug. These results suggest that under inflammatory conditions associated with asthma, phenolic ?(2)-agonists may be subject to peroxidase-catalyzed nitration that could potentially diminish their therapeutic efficacy. PMID:20974700

Reszka, Krzysztof J; Sallans, Larry; Macha, Stephen; Brown, Kari; McGraw, Dennis W; Kovacic, Melinda Butsch; Britigan, Bradley E

2011-02-01

53

Structure-activity relationship studies toward the discovery of selective apelin receptor agonists.  

PubMed

Apelin is the endogenous ligand for the previously orphaned G protein-coupled receptor APJ. Apelin and its receptor are widely distributed in the brain, heart, and vasculature, and are emerging as an important regulator of body fluid homeostasis and cardiovascular functions. To further progress in the pharmacology and the physiological role of the apelin receptor, the development of small, bioavailable agonists and antagonists of the apelin receptor, is crucial. In this context, E339-3D6 (1) was described as the first nonpeptidic apelin receptor agonist. We show here that 1 is actually a mixture of polymethylated species, and we describe an alternative and versatile solid-phase approach that allows access to highly pure 27, the major component of 1. This approach was also applied to prepare a series of derivatives in order to identify the crucial structural determinants required for the ligand to maintain its affinity for the apelin receptor as well as its capacity to promote apelin receptor signaling and internalization. The study of the structure-activity relationships led to the identification of ligands 19, 21, and 38, which display an increased affinity compared to that of 27. The latter and 19 behave as full agonists with regard to cAMP production and apelin receptor internalization, whereas 21 is a biased agonist toward cAMP production. Interestingly, the three ligands display a much higher stability in mouse plasma (T1/2 > 10 h) than the endogenous apelin-17 peptide 2 (T1/2 < 4 min). PMID:24625069

Margathe, Jean-François; Iturrioz, Xavier; Alvear-Perez, Rodrigo; Marsol, Claire; Riché, Stéphanie; Chabane, Hadjila; Tounsi, Nassera; Kuhry, Maxime; Heissler, Denis; Hibert, Marcel; Llorens-Cortes, Catherine; Bonnet, Dominique

2014-04-10

54

Structure-Activity Relationships for Side Chain Oxysterol Agonists of the Hedgehog Signaling Pathway  

PubMed Central

Oxysterols (OHCs) are byproducts of cholesterol oxidation that are known to activate the Hedeghog (Hh) signaling pathway. While OHCs that incorporate hydroxyl groups throughout the scaffold are known, those that act as agonists of Hh signaling primarily contain a single hydroxyl on the alkyl side chain. We sought to further explore how side chain hydroxylation patterns affect oxysterol-mediated Hh activation, by performing a structure–activity relationship study on a series of synthetic OHCs. The most active analogue, 23(R)-OHC (35), demonstrated potent activation of Hh signaling in two Hh-dependent cell lines (EC50 values 0.54–0.65 ?M). In addition, OHC 35 was approximately 3-fold selective for the Hh pathway as compared to the liver X receptor, a nuclear receptor that is also activated by endogenous OHCs. Finally, 35 induced osteogenic differentiation and osteoblast formation in cultured cells, indicating functional agonism of the Hh pathway. PMID:24900386

2012-01-01

55

Weakly Supervised Recognition of Daily Life Activities with Wearable Sensors  

E-print Network

and nontrivial in particular for long-term recordings. There exists a wide range of annotation techniques number of activities and long periods of time. Experience sampling is based on periodic prompts of a userWeakly Supervised Recognition of Daily Life Activities with Wearable Sensors Maja Stikic, Diane

56

Activation of the G-protein-coupled receptor 119: a conformation-based hypothesis for understanding agonist response.  

PubMed

The synthesis and properties of the bridged piperidine (oxaazabicyclo) compounds 8, 9, and 11 are described. A conformational analysis of these structures is compared with the representative GPR119 ligand 1. These results and the differences in agonist pharmacology are used to formulate a conformation-based hypothesis to understand activation of the GPR119 receptor. We also show for these structures that the agonist pharmacology in rat masks the important differences in human pharmacology. PMID:21361292

McClure, Kim F; Darout, Etzer; Guimarães, Cristiano R W; DeNinno, Michael P; Mascitti, Vincent; Munchhof, Michael J; Robinson, Ralph P; Kohrt, Jeffrey; Harris, Anthony R; Moore, Dianna E; Li, Bryan; Samp, Lacey; Lefker, Bruce A; Futatsugi, Kentaro; Kung, Daniel; Bonin, Paul D; Cornelius, Peter; Wang, Ruduan; Salter, Eben; Hornby, Sam; Kalgutkar, Amit S; Chen, Yue

2011-03-24

57

Neuromuscular Contributions to Age-Related Weakness  

PubMed Central

Background. Declines in skeletal muscle mass and quality are important factors contributing to age-related weakness. Neural activation of agonist and antagonist muscles may also be important contributing factors. Methods. We conducted a review of the scientific literature on older adults to determine (a) methodologies used to quantify activation, (b) the potential role of agonist and antagonist activation on weakness, and (c) some possible neurophysiological mechanisms that may underlie impaired activation. Results. The cumulative evidence indicates that agonist activation is impaired in some, but not all, older adults and that this impairment contributes to age-related weakness. It is possible that antagonist coactivation also plays a role in age-related weakness, though a definitive link has not been established. Conclusion. Future research should focus on improving quantitative measurement and mechanistic understanding of impaired activation with aging. PMID:21415261

Clark, David J.

2012-01-01

58

Polyyne Hybrid Compounds from Notopterygium incisum with Peroxisome Proliferator-Activated Receptor Gamma Agonistic Effects.  

PubMed

In the search for peroxisome proliferator-activated receptor gamma (PPAR?) active constituents from the roots and rhizomes of Notopterygium incisum, 11 new polyacetylene derivatives (1-11) were isolated. Their structures were elucidated by NMR and HRESIMS as new polyyne hybrid molecules of falcarindiol with sesquiterpenoid or phenylpropanoid moieties, named notoethers A-H (1-8) and notoincisols A-C (9-11), respectively. Notoincisol B (10) and notoincisol C (11) represent two new carbon skeletons. When tested for PPAR? activation in a luciferase reporter assay with HEK-293 cells, notoethers A-C (1-3), notoincisol A (9), and notoincisol B (10) showed promising agonistic activity (EC50 values of 1.7 to 2.3 ?M). In addition, notoincisol A (9) exhibited inhibitory activity on NO production of stimulated RAW 264.7 macrophages. PMID:25333853

Liu, Xin; Kunert, Olaf; Blunder, Martina; Fakhrudin, Nanang; Noha, Stefan M; Malainer, Clemens; Schinkovitz, Andreas; Heiss, Elke H; Atanasov, Atanas G; Kollroser, Manfred; Schuster, Daniela; Dirsch, Verena M; Bauer, Rudolf

2014-11-26

59

Identity of Endogenous NMDAR Glycine Site Agonist in Amygdala Is Determined by Synaptic Activity Level  

PubMed Central

Mechanisms of NMDA receptor-dependent synaptic plasticity contribute to the acquisition and retention of conditioned fear memory. However, synaptic rules which may determine the extent of NMDA receptor activation in the amygdala, a key structure implicated in fear learning, remain unknown. Here we show that the identity of the NMDAR glycine site agonist at synapses in the lateral nucleus of the amygdala may depend on the level of synaptic activation. Tonic activation of NMDARs at synapses in the amygdala under low-activity conditions is supported by ambient D-serine, whereas glycine may be released from astrocytes in response to afferent impulses. The release of glycine may decode the increases in afferent activity levels into enhanced NMDAR-mediated synaptic events, serving an essential function in the induction of NMDAR-dependent long-term potentiation in fear conditioning pathways. PMID:23612301

Li, Yan; Sacchi, Silvia; Pollegioni, Loredano; Basu, Alo C.; Coyle, Joseph T.; Bolshakov, Vadim Y.

2013-01-01

60

NOpiates: Novel Dual Action Neuronal Nitric Oxide Synthase Inhibitors with ?-Opioid Agonist Activity  

PubMed Central

A novel series of benzimidazole designed multiple ligands (DMLs) with activity at the neuronal nitric oxide synthase (nNOS) enzyme and the ?-opioid receptor was developed. Targeting of the structurally dissimilar heme-containing enzyme and the ?-opioid GPCR was predicated on the modulatory role of nitric oxide on ?-opioid receptor function. Structure–activity relationship studies yielded lead compound 24 with excellent nNOS inhibitory activity (IC50 = 0.44 ?M), selectivity over both endothelial nitric oxide synthase (10-fold) and inducible nitric oxide synthase (125-fold), and potent ?-opioid binding affinity, Ki = 5.4 nM. The functional activity as measured in the cyclic adenosine monosphospate secondary messenger assay resulted in full agonist activity (EC50 = 0.34 ?M). This work represents a novel approach in the development of new analgesics for the treatment of pain. PMID:24900459

2012-01-01

61

Peroxisome proliferator-activated receptor ? agonists inhibit the proliferation and invasion of human colon cancer cells  

PubMed Central

Background and aims Data regarding the effect of peroxisome proliferator?activated receptor ? (PPAR??) ligands on the invasive ability of colon cancer cells are currently limited. This study was designed to examine the effects of PPAR?? agonists on the proliferation and invasion of two colon cancer cells to identify the role of PPAR?? in colon cancer growth and metastasis. Methods SW480 and LS174T cells were treated with PPAR?? ligands, pioglitazone and 15?deoxy??(12,14)?prostaglandin J2 (15d?PGJ2), as well as their combinations with the PPAR?? antagonist GW9662. MTT assay was used to determine the antiproliferative effects. Cell cycle analysis was conducted by flow cytometry. The mRNA and protein expression were detected by reverse transcriptase polymerase chain reaction (RT?PCR) and western blot, respectively. The invasive ability of cells was determined by the BD BioCoat Matrige invasion chamber. Results Pioglitazone and 15d?PGJ2 inhibited the proliferation of both colon cancer cell lines in a dose?dependent manner. This growth inhibitory effect was reversed by GW9662. Results from flow cytometry demonstrated G1 arrest following treatment with pioglitazone and 15d?PGJ2. The expression of matrix metalloproteinase?7 (MMP?7) was only detected in LS174T cells, while its tissue inhibitor?1 (TIMP?1) was expressed in both colon cancer cells. 15d?PGJ2 and pioglitazone downregulated MMP?7 expression and upregulated TIMP?1 expression. PPAR?? agonists can only inhibit invasive activity of LS174T cells. Conclusions PPAR?? agonists have inhibitory effects on the proliferation of colon cancer cell lines associated with G1 cell cycle arrest and invasive activity. The latter effect is demonstrated in certain cell lines through the down?regulation of MMP?7 synthesis. PMID:17551074

Shen, Dan; Deng, Changsheng; Zhang, Ming

2007-01-01

62

Activation of various subtypes of G-protein alpha subunits by partial agonists of the adenosine A1 receptor.  

PubMed

The activation of different G protein subtypes by the rat adenosine A1 receptor initiated by stimulation with the full agonist 2-chloro-N6-cyclopentyladenosine (CCPA) and by six structurally distinct partial agonists of this receptor was investigated. Endogenous G protein alpha subunits in rat cortical membranes were inactivated by N-ethylmaleimide (NEM). Activation of rat recombinant myristoylated alpha(o), alpha(i1), alpha(i2) and alpha(i3) by partial agonists in comparison to the full agonist was assessed by guanosine-5'-(gamma-[35S]thio)triphosphate ([35S]GTPgammaS) binding after reconstitution of G protein alpha subunits with the adenosine A1 receptor in N-ethylmaleimide-treated membranes. 2-Chloro-N6-cyclopentyladenosine and 3' -deoxy-N6-cyclopentyladenosine (3'-d-CPA), the partial agonist with the highest intrinsic activity, were significantly more potent in activation of alpha(i) subtypes than alpha(o). In contrast, 5'-methylthioadenosine (MeSA), 2'-deoxy-2-chloroadenosine (cladribine), 2'-deoxy-N6-cyclopentyladenosine (2'-d-CPA), 2-phenylaminoadenosine (CV 1808) and C8-aminopropyl-N6-cyclopentyladenosine (C8-aminopropyl-CPA) did not exhibit higher potency for Go or any Gi subtype. All partial agonists, although carrying structurally different modifications, showed higher relative intrinsic activities in activation of Gi than of Go, indicating that Gi-coupled pathways may be activated selectively via the A1 receptor by partial agonists, but not Go-mediated responses. PMID:9825727

Lorenzen, A; Lang, H; Schwabe, U

1998-11-15

63

Synthesis and structure-activity relationship of dihydrobenzofuran derivatives as novel human GPR119 agonists.  

PubMed

Through appropriate medicinal chemistry design tactics and computer-assisted conformational modeling, the initial lead A was evolved into a series of dihydrobenzofuran derivatives 3 as potent GPR119 agonists. This Letter describes the optimization of general structure 3, including the substituent(s) on dihydrobenzofuran, the R(1) attachment on right-hand piperidine nitrogen, and the left-hand piperidine/piperazine and its attachment R(2). The efforts led to the identification of compounds 13c and 24 as potent human GPR119 modulators with favorable metabolic stability, ion channel activity, and PXR profiles. PMID:24755425

Ye, Xiang-Yang; Morales, Christian L; Wang, Ying; Rossi, Karen A; Malmstrom, Sarah E; Abousleiman, Mojgan; Sereda, Larisa; Apedo, Atsu; Robl, Jeffrey A; Miller, Keith J; Krupinski, John; Wacker, Dean A

2014-06-01

64

Gating of TRPM8 channels activated by cold and chemical agonists in planar lipid bilayers  

PubMed Central

The TRPM8 ion channel is a major sensor of environmental cold temperatures. It is activated by cold and chemical agonists, such as menthol and icilin. The activation of these channels both by cold and cooling agents requires the presence of the membrane phospholipid, phosphatidylinositol 4,5-bisphosphate (PIP2). The mechanism of TRPM8 activation by physical and chemical factors is unknown and the involvement of cellular signaling pathways has been considered. Here we have characterized the gating mechanism of the rat TRPM8 reconstituted in planar lipid bilayers and its activation by different stimuli. In this system the influence of cellular signaling pathways can be excluded. We found that TRPM8 activated by cold exhibits steep temperature dependence (Q10?40), and the channel openings are accompanied by large changes in entropy and enthalpy, suggesting a substantial conformation change. TRPM8 channel behavior upon menthol and icilin activation was distinguishable and the effect of icilin depended on the presence of calcium on the intracellular side of the protein. Here we also demonstrate that PIP2 is the prime factor that impacts the gating of TRPM8 and other phosphoinositides are less efficient in supporting channel activity. Menthol increases the potency of PIP2 to activate the channels, and increases binding of phosphoinositides to the full-length channel protein. Our data demonstrate conclusively that TRPM8 is gated by cold and its chemical agonists directly, and that dependence of its gating on PIP2 is a result of direct specific interactions with the lipid. PMID:20844147

Zakharian, Eleonora; Cao, Chike; Rohacs, Tibor

2010-01-01

65

Design Novel Dual Agonists for Treating Type-2 Diabetes by Targeting Peroxisome Proliferator-Activated Receptors with Core Hopping Approach  

PubMed Central

Owing to their unique functions in regulating glucose, lipid and cholesterol metabolism, PPARs (peroxisome proliferator-activated receptors) have drawn special attention for developing drugs to treat type-2 diabetes. By combining the lipid benefit of PPAR-alpha agonists (such as fibrates) with the glycemic advantages of the PPAR-gamma agonists (such as thiazolidinediones), the dual PPAR agonists approach can both improve the metabolic effects and minimize the side effects caused by either agent alone, and hence has become a promising strategy for designing effective drugs against type-2 diabetes. In this study, by means of the powerful “core hopping” and “glide docking” techniques, a novel class of PPAR dual agonists was discovered based on the compound GW409544, a well-known dual agonist for both PPAR-alpha and PPAR-gamma modified from the farglitazar structure. It was observed by molecular dynamics simulations that these novel agonists not only possessed the same function as GW409544 did in activating PPAR-alpha and PPAR-gamma, but also had more favorable conformation for binding to the two receptors. It was further validated by the outcomes of their ADME (absorption, distribution, metabolism, and excretion) predictions that the new agonists hold high potential to become drug candidates. Or at the very least, the findings reported here may stimulate new strategy or provide useful insights for discovering more effective dual agonists for treating type-2 diabetes. Since the “core hopping” technique allows for rapidly screening novel cores to help overcome unwanted properties by generating new lead compounds with improved core properties, it has not escaped our notice that the current strategy along with the corresponding computational procedures can also be utilized to find novel and more effective drugs for treating other illnesses. PMID:22685582

Xu, Wei-Ren; Wang, Run-Ling; Chou, Kuo-Chen

2012-01-01

66

Protection from liver fibrosis by a peroxisome proliferator-activated receptor ? agonist.  

PubMed

Peroxisome proliferator-activated receptor delta (PPAR?), a member of the nuclear receptor family, is emerging as a key metabolic regulator with pleiotropic actions on various tissues including fat, skeletal muscle, and liver. Here we show that the PPAR? agonist KD3010, but not the well-validated GW501516, dramatically ameliorates liver injury induced by carbon tetrachloride (CCl(4)) injections. Deposition of extracellular matrix proteins was lower in the KD3010-treated group than in the vehicle- or GW501516-treated group. Interestingly, profibrogenic connective tissue growth factor was induced significantly by GW501516, but not by KD3010, following CCl(4) treatment. The hepatoprotective and antifibrotic effect of KD3010 was confirmed in a model of cholestasis-induced liver injury and fibrosis using bile duct ligation for 3 wk. Primary hepatocytes treated with KD3010 but not GW501516 were protected from starvation or CCl(4)-induced cell death, in part because of reduced reactive oxygen species production. In conclusion, our data demonstrate that an orally active PPAR? agonist has hepatoprotective and antifibrotic effects in animal models of liver fibrosis, suggesting a possible mechanistic and therapeutic approach in treating patients with chronic liver diseases. PMID:22538808

Iwaisako, Keiko; Haimerl, Michael; Paik, Yong-Han; Taura, Kojiro; Kodama, Yuzo; Sirlin, Claude; Yu, Elizabeth; Yu, Ruth T; Downes, Michael; Evans, Ronald M; Brenner, David A; Schnabl, Bernd

2012-05-22

67

A selective peroxisome proliferator-activated receptor ? agonist promotes reverse cholesterol transport  

PubMed Central

The peroxisome proliferator-activated receptors (PPARs) are dietary lipid sensors that regulate fatty acid and carbohydrate metabolism. The hypolipidemic effects of the fibrate drugs and the antidiabetic effects of the glitazone drugs in humans are due to activation of the ? (NR1C1) and ? (NR1C3) subtypes, respectively. By contrast, the therapeutic potential of the ? (NR1C2) subtype is unknown, due in part to the lack of selective ligands. We have used combinatorial chemistry and structure-based drug design to develop a potent and subtype-selective PPAR? agonist, GW501516. In macrophages, fibroblasts, and intestinal cells, GW501516 increases expression of the reverse cholesterol transporter ATP-binding cassette A1 and induces apolipoprotein A1-specific cholesterol efflux. When dosed to insulin-resistant middle-aged obese rhesus monkeys, GW501516 causes a dramatic dose-dependent rise in serum high density lipoprotein cholesterol while lowering the levels of small-dense low density lipoprotein, fasting triglycerides, and fasting insulin. Our results suggest that PPAR? agonists may be effective drugs to increase reverse cholesterol transport and decrease cardiovascular disease associated with the metabolic syndrome X. PMID:11309497

Oliver, William R.; Shenk, Jennifer L.; Snaith, Mike R.; Russell, Caroline S.; Plunket, Kelli D.; Bodkin, Noni L.; Lewis, Michael C.; Winegar, Deborah A.; Sznaidman, Marcos L.; Lambert, Millard H.; Xu, H. Eric; Sternbach, Daniel D.; Kliewer, Steven A.; Hansen, Barbara C.; Willson, Timothy M.

2001-01-01

68

The naturally occurring aliphatic isothiocyanates sulforaphane and erucin are weak agonists but potent non-competitive antagonists of the aryl hydrocarbon receptor.  

PubMed

As the Ah receptor target gene products play a critical role in chemical carcinogenesis, antagonists are considered as potential chemopreventive agents. It is demonstrated in this paper that the isothiocyanates R,S-sulforaphane and erucin are non-competitive antagonists of the aryl hydrocarbon (Ah) receptor. Both isothiocyanates were poor agonists for the receptor and elevated CYP1A1 mRNA levels only modestly when incubated with precision-cut rat liver slices. In contrast, the classical Ah receptor agonist benzo[a]pyrene was a potent inducer of CYP1A1 mRNA levels, with this effect being effectively antagonized by the two isothiocyanates. In further studies, it was demonstrated that R,S-sulforaphane could both prevent the interaction of and displace already bound benzo[a]pyrene from the Ah receptor, but no concentration dependency was observed with respect to the isothiocyanate. Both erucin and R,S-sulforaphane antagonized the benzo[a]pyrene-mediated increase in the CYP1A-mediated O-deethylation of ethoxyresorufin in rat precision-cut liver slices. Of the two isomers of R,S-sulforaphane, the naturally occurring R-isomer was more effective than the S-isomer in antagonizing the activation of the Ah receptor by benzo[a]pyrene. Antagonism of the Ah receptor may be a major contributor to the established chemoprevention of aliphatic isothiocyanates. PMID:22643862

Abdull Razis, Ahmad F; Hanlon, Natalya; Soltys, Ewa; Krizova, Veronika; Iori, Renato; Plant, Kathryn E; Plant, Nick; Ioannides, Costas

2012-10-01

69

Peroxisome proliferator-activated receptor-gamma agonists promote differentiation and antioxidant defenses of oligodendrocyte progenitor cells.  

PubMed

Several lines of evidence suggest that peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists may control brain inflammation and, therefore, may be useful for the treatment of human CNS inflammatory conditions. The PPAR-gamma agonists delay the onset and ameliorate clinical manifestations in animal demyelinating disease models, in which the beneficial effects are thought to be mainly related to anti-inflammatory effects on peripheral and brain immune cells. Direct effects on neurons, oligodendrocytes, and other CNS resident cells cannot be excluded, however. To analyze potential direct actions of PPAR-gamma agonists on oligodendrocytes, we investigated the effects of both natural (15-deoxy Delta prostaglandin J2) and synthetic (pioglitazone) PPAR-gamma agonists in primary cultures of rat oligodendrocyte progenitor cells. The PPAR-gamma agonists promoted oligodendrocyte progenitor cell differentiation and enhanced their antioxidant defenses by increasing levels of catalase and copper-zinc superoxide dismutase while maintaining the overall homeostasis of the glutathione system. Protective effects were abolished in the presence of the specific PPAR-gamma antagonist GW9662, indicating that they are specifically dependent on PPAR-gamma. These observations suggest that in addition to their known anti-inflammatory effects, PPAR-gamma agonists may protect oligodendrocyte progenitor cells by preserving their integrity and favoring their differentiation into myelin-forming cells. Thus, PPAR-gamma may promote recovery from demyelination by direct effects on oligodendrocytes. PMID:19535992

Bernardo, Antonietta; Bianchi, Daniela; Magnaghi, Valerio; Minghetti, Luisa

2009-07-01

70

Orally active benzoxazole derivative as 5-HT3 receptor partial agonist for treatment of diarrhea-predominant irritable bowel syndrome.  

PubMed

During our search for therapeutic agents to treat diarrhea-predominant IBS, we found that 2-substituted benzoxazole derivatives have a characteristic 5-HT(3) receptor partial agonist activity with high affinity. Some of these compounds showed high in vitro metabolical stability, and 6g showed marked antidiarrhetic activity with little side effect of constipation in in vivo tests. Our results indicate that 5-HT(3) receptor partial agonists might be superior as therapeutic agents to the drugs currently used for IBS treatment. PMID:16250667

Yoshida, Satoshi; Shiokawa, Sojiro; Kawano, Ken-ichi; Ito, Tomoko; Murakami, Hiroshi; Suzuki, Hisashi; Sato, Yasuo

2005-11-01

71

Imidazoquinoline TLR8 agonists activate human newborn monocytes and dendritic cells via adenosine-refractory and caspase-1-dependent pathways  

PubMed Central

Background Newborns suffer frequent infection and manifest impaired vaccine responses, motivating a search for neonatal vaccine adjuvants. Alum is a neonatal adjuvant, but may confer a Th2 bias. Toll-like receptor (TLR) agonists are candidate adjuvants, but human neonatal cord blood monocytes (Mos) demonstrate impaired Th1-polarizing responses to many TLR agonists due to plasma adenosine acting via cAMP. TLR8 agonists, including imidazoquinolines (IMQs) such as the small synthetic 3M-002, induce adult-level TNF from neonatal Mos, but the scope and mechanisms of IMQ-induced activation of neonatal Mos and Mo-derived dendritic cells (MoDCs) have not been reported. Objectives To characterize IMQ-induced activation of neonatal Mos and MoDCs. Methods Neonatal cord and adult peripheral blood Mos and MoDCs were cultured in autologous plasma; Alum- and TLR agonist-induced cytokines and co-stimulatory molecules were measured. TLR8 and inflammasome function were assayed using siRNA and western blotting/caspase-1 inhibitory peptide, respectively. The ontogeny of TLR8 agonist–induced cytokine responses was defined in Rhesus macaque whole blood ex vivo. Results IMQs were more potent and effective than Alum at inducing TNF and IL-1? from Mos. 3M-002 induced robust TLR pathway transcriptome activation and Th1-polarizing cytokine production in neonatal and adult Mos and MoDCs, signaling via TLR8 in an adenosine/cAMP- refractory manner. Newborn MoDCs displayed impaired LPS/ATP-induced caspase-1-mediated IL-1? production, but robust 3M-002-induced caspase-1-mediated inflammasome activation independent of exogenous ATP. TLR8-IMQs induced robust TNF and IL-1? in whole blood of Rhesus macaques at birth and infancy. Conclusions IMQ TLR8 agonists engage adenosine-refractory TLR8 and inflammasome pathways to induce robust Mo and MoDC activation and represent promising neonatal adjuvants. PMID:22521247

Philbin, Victoria J.; Dowling, David J.; Gallington, Leighanne C.; Cortes, Guadalupe; Tan, Zhen; Suter, Eugenie E.; Chi, Kevin W.; Shuckett, Ariel; Stoler-Barak, Liat; Tomai, Mark; Miller, Richard L.; Mansfield, Keith; Levy, Ofer

2012-01-01

72

The effects of agonist and antagonist muscle activation on the knee extension moment-angle relationship in adults and children.  

PubMed

The present study examined the effect of agonist activation and antagonist co-activation on the shape of the knee extension moment-angle relationship in adults and children. Isometric knee extension maximum voluntary contractions (MVCs) were performed at every 5 degrees of knee flexion between 55 degrees and 90 degrees (full extension = 0 degrees) by ten men, ten women, ten boys and ten girls. For each trial, the knee extensors' voluntary activation level was quantified using magnetic stimulation and the level of antagonist co-activation was quantified from their electromyographical activity. Peak MVC moment was greater for men (264 +/- 63 N m) than women (177 +/- 60 N m), and greater for adults than children (boys 78 +/- 17 N m, girls 91 +/- 28 N m) (p < 0.01). The agonistic activation level was greater for adults (approximately 85%) than children (approximately 70%). Similarly, antagonist co-activation was greater for adults than children, but relative to the agonist moment there were no differences between groups (all groups 7-8%). Correcting the peak moment for agonist and antagonist activation levels resulted in moments produced by fully activated agonist muscles of 334 +/- 83, 229 +/- 70, 114.2 +/- 32 and 147 +/- 46 N m, for men, women, boys and girls, respectively. Although correcting for shifts in joint angle during contraction altered the angle of peak moment by approximately 10 degrees (p < 0.01), the peak moment occurred at approximately 60 degrees for all groups. Changes in tendon stiffness, muscle size and architecture, and the pattern of the moment arm-angle relationship may in combination occur so that as children develop and mature into adults the shape of the moment-angle relationship is not altered. PMID:19471955

O'Brien, Thomas D; Reeves, Neil D; Baltzopoulos, Vasilios; Jones, David A; Maganaris, Constantinos N

2009-08-01

73

Identification of a potent synthetic FXR agonist with an unexpected mode of binding and activation  

SciTech Connect

The farnesoid X receptor (FXR), a member of the nuclear hormone receptor family, plays important roles in the regulation of bile acid and cholesterol homeostasis, glucose metabolism, and insulin sensitivity. There is intense interest in understanding the mechanisms of FXR regulation and in developing pharmaceutically suitable synthetic FXR ligands that might be used to treat metabolic syndrome. We report here the identification of a potent FXR agonist (MFA-1) and the elucidation of the structure of this ligand in ternary complex with the human receptor and a coactivator peptide fragment using x-ray crystallography at 1.9-{angstrom} resolution. The steroid ring system of MFA-1 binds with its D ring-facing helix 12 (AF-2) in a manner reminiscent of hormone binding to classical steroid hormone receptors and the reverse of the pose adopted by naturally occurring bile acids when bound to FXR. This binding mode appears to be driven by the presence of a carboxylate on MFA-1 that is situated to make a salt-bridge interaction with an arginine residue in the FXR-binding pocket that is normally used to neutralize bound bile acids. Receptor activation by MFA-1 differs from that by bile acids in that it relies on direct interactions between the ligand and residues in helices 11 and 12 and only indirectly involves a protonated histidine that is part of the activation trigger. The structure of the FXR:MFA-1 complex differs significantly from that of the complex with a structurally distinct agonist, fexaramine, highlighting the inherent plasticity of the receptor.

Soisson, Stephen M.; Parthasarathy, Gopalakrishnan; Adams, Alan D.; Sahoo, Soumya; Sitlani, Ayesha; Sparrow, Carl; Cui, Jisong; Becker, Joseph W. (Merck)

2008-07-08

74

Identification of PPARgamma Partial Agonists of Natural Origin (II): In Silico Prediction in Natural Extracts with Known Antidiabetic Activity  

PubMed Central

Background Natural extracts have played an important role in the prevention and treatment of diseases and are important sources for drug discovery. However, to be effectively used in these processes, natural extracts must be characterized through the identification of their active compounds and their modes of action. Methodology/Principal Findings From an initial set of 29,779 natural products that are annotated with their natural source and using a previously developed virtual screening procedure (carefully validated experimentally), we have predicted as potential peroxisome proliferators-activated receptor gamma (PPAR?) partial agonists 12 molecules from 11 extracts known to have antidiabetic activity. Six of these molecules are similar to molecules with described antidiabetic activity but whose mechanism of action is unknown. Therefore, it is plausible that these 12 molecules could be the bioactive molecules responsible, at least in part, for the antidiabetic activity of the extracts containing them. In addition, we have also identified as potential PPAR? partial agonists 10 molecules from 16 plants with undescribed antidiabetic activity but that are related (i.e., they are from the same genus) to plants with known antidiabetic properties. None of the 22 molecules that we predict as PPAR? partial agonists show chemical similarity with a group of 211 known PPAR? partial agonists obtained from the literature. Conclusions/Significance Our results provide a new hypothesis about the active molecules of natural extracts with antidiabetic properties and their mode of action. We also suggest plants with undescribed antidiabetic activity that may contain PPAR? partial agonists. These plants represent a new source of potential antidiabetic extracts. Consequently, our work opens the door to the discovery of new antidiabetic extracts and molecules that can be of use, for instance, in the design of new antidiabetic drugs or functional foods focused towards the prevention/treatment of type 2 Diabetes Mellitus. PMID:23405231

Guasch, Laura; Sala, Esther; Mulero, Miquel; Valls, Cristina; Salvado, Maria Josepa; Pujadas, Gerard; Garcia-Vallve, Santiago

2013-01-01

75

Identity of endogenous NMDAR glycine site agonist in amygdala is determined by synaptic activity level.  

PubMed

Mechanisms of N-methyl-D-aspartate receptor-dependent synaptic plasticity contribute to the acquisition and retention of conditioned fear memory. However, synaptic rules which may determine the extent of N-methyl-D-aspartate receptor activation in the amygdala, a key structure implicated in fear learning, remain unknown. Here we show that the identity of the N-methyl-D-aspartate receptor glycine site agonist at synapses in the lateral nucleus of the amygdala may depend on the level of synaptic activation. Tonic activation of N-methyl-D-aspartate receptors at synapses in the amygdala under low activity conditions is supported by ambient D-serine, whereas glycine may be released from astrocytes in response to afferent impulses. The release of glycine may decode the increases in afferent activity levels into enhanced N-methyl-D-aspartate receptor-mediated synaptic events, serving an essential function in the induction of N-methyl-D-aspartate receptor-dependent long-term potentiation in fear conditioning pathways. PMID:23612301

Li, Yan; Sacchi, Silvia; Pollegioni, Loredano; Basu, Alo C; Coyle, Joseph T; Bolshakov, Vadim Y

2013-01-01

76

The in vivo gastrointestinal activity of TD-5108, a selective 5-HT(4) receptor agonist with high intrinsic activity.  

PubMed

The in vivo preclinical pharmacodynamic profile of TD-5108, a selective 5-HT(4) receptor agonist with high intrinsic activity, was compared to that of the clinically studied gastrointestinal pro-kinetic agents, tegaserod, cisapride and mosapride. The activity of TD-5108 was evaluated in guinea pig colonic transit, rat oesophageal relaxation and dog gastrointestinal smooth muscle contractility models. Subcutaneous administration of TD-5108, tegaserod, cisapride and mosapride increased guinea pig colonic transit (rank order of potencies: TD-5108 > tegaserod > cisapride > mosapride). Following intravenous and intraduodenal dosing, TD-5108, tegaserod, cisapride and mosapride produced dose-dependent relaxation of the rat oesophagus. On a molar basis, TD-5108 was approximately twofold less potent than tegaserod following intravenous dosing but 6- or 86-fold more potent than cisapride or mosapride, respectively, and 9- or 18-fold more potent than tegaserod or cisapride, respectively, after intraduodenal administration. Orally dosed TD-5108 increased the contractility of the canine antrum, duodenum and jejunum with higher potency than tegaserod. The selective 5-HT(4) receptor agonist, TD-5108, demonstrates robust in vivo activity in the guinea pig, rat and dog gastrointestinal tracts. PMID:18408918

Beattie, D T; Armstrong, S R; Shaw, J P; Marquess, D; Sandlund, C; Smith, J A M; Taylor, J A; Humphrey, P P A

2008-07-01

77

The peroxisome-proliferator activated receptor-? agonist pioglitazone modulates aberrant T cell responses in systemic lupus erythematosus  

PubMed Central

PPAR-? agonists can suppress autoimmune responses and renal inflammation in murine lupus but the mechanisms implicated in this process remain unclear. We tested the effect of the PPAR-? agonist pioglitazone in human lupus and control PBMCs with regards to gene regulation and various functional assays. By Affymetrix microarray analysis, several T cell-related pathways were significantly highlighted in pathway analysis in lupus PBMCs. Transcriptional network analysis showed IFN-? as an important regulatory node, with pioglitazone treatment inducing transcriptional repression of various genes implicated in T cell responses. Confirmation of these suppressive effects was observed specifically in purified CD4+ T cells. Pioglitazone downregulated lupus CD4+ T cell effector proliferation and activation, while it significantly increased proliferation and function of lupus T regulatory cells. We conclude that PPAR-? agonists selectively modulate CD4+ T cell function in SLE. supporting the concept that pioglitazone and related-agents should be explored as potential therapies in this disease. PMID:23962407

Zhao, Wenpu; Berthier, Celine C.; Lewis, Emily E.; McCune, W. Joseph; Kretzler, Matthias; Kaplan, Mariana J.

2013-01-01

78

T-Cell Activation: A Queuing Theory Analysis at Low Agonist Density J. R. Wedagedera* and N. J. Burroughsy  

E-print Network

T-Cell Activation: A Queuing Theory Analysis at Low Agonist Density J. R. Wedagedera* and N. J, University of Warwick, Coventry, United Kingdom ABSTRACT We analyze a simple linear triggering model of the T-cell,arobustnessanalysisshowsthatthesepropertiesaredegradedwhenthequeueparameters aresubject tovariation--for example, under stochasticity in the ligand number in the cell-cell interface

Wedagedera, Janak R.

79

Synthesis of functionalized 1,8-naphthyridinones and their evaluation as novel, orally active CB1 receptor inverse agonists  

Microsoft Academic Search

Synthesis, SAR, and binding affinities are described for a new class of 1,8-naphthyridinone CB1 receptor specific inverse agonists. Food intake, knockout mouse, and pharmacokinetic evaluation of 14 indicate that this compound is an effective orally active modulator of CB1.

John S. Debenham; Christina B. Madsen-Duggan; Thomas F. Walsh; Junying Wang; Xinchun Tong; George A. Doss; Julie Lao; Tung M. Fong; Marie-Therese Schaeffer; Jing Chen Xiao; Cathy R.-R. C. Huang; Chun-Pyn Shen; Yue Feng; Donald J. Marsh; D. Sloan Stribling; Lauren P. Shearman; Alison M. Strack; D. Euan MacIntyre; Mark T. Goulet

2006-01-01

80

In vitro effect of nonsteroidal ecdysone agonist RH 5849 on fat body acid phosphatase activity in rice moth, Corcyra cephalonica (Insecta).  

PubMed

Nonsteroidal ecdysone agonist stimulates acid phosphatase activity in the fat body in vitro cultures obtained from ligated late-last instar larvae of Corcyra cephalonica. The agonist also stimulates general protein synthesis. This stimulation is both time as well as dose dependent (up to a dose of 1000 ng of the agonist). However, still higher concentrations (1500-4000 ng) tend to depress the degree of stimulation. PMID:1768263

Ashok, M; Dutta-Gupta, A

1991-05-01

81

Muscarinic agonists with antipsychotic-like activity: structure-activity relationships of 1,2,5-thiadiazole analogues with functional dopamine antagonist activity.  

PubMed

Muscarinic agonists were tested in two models indicative of clinical antipsychotic activity: conditioned avoidance responding (CAR) in rats and inhibition of apomorphine-induced climbing in mice. The standard muscarinic agonists oxotremorine and pilocarpine were both active in these tests but showed little separation between efficacy and cholinergic side effects. Structure-activity relationships of the alkylthio-1,2,5-thiadiazole azacyclic type muscarinic partial agonists are shown, revealing the exo-6-(3-propyl/butylthio-1,2, 5-thiadiazol-4-yl)-1-azabicyclo[3.2.1]octane analogues (4a,b and 9a, b) to be the most potent antipsychotic agents with large separation between efficacy and cholinergic side effects. The lack of enantiomeric selectivity suggests the pharmacophoric elements are in the mirror plane of the compounds. A model explaining the potency differences of closely related compounds is offered. The data suggest that muscarinic agonists act as functional dopamine antagonists and that they could become a novel treatment of psychotic patients. PMID:9784113

Sauerberg, P; Jeppesen, L; Olesen, P H; Rasmussen, T; Swedberg, M D; Sheardown, M J; Fink-Jensen, A; Thomsen, C; Thøgersen, H; Rimvall, K; Ward, J S; Calligaro, D O; DeLapp, N W; Bymaster, F P; Shannon, H E

1998-10-22

82

Structure-Activity Relationship Study around Guanabenz Identifies Two Derivatives Retaining Antiprion Activity but Having Lost ?2-Adrenergic Receptor Agonistic Activity.  

PubMed

Guanabenz (GA) is an orally active ?2-adrenergic agonist that has been used for many years for the treatment of hypertension. We recently described that GA is also active against both yeast and mammalian prions in an ?2-adrenergic receptor-independent manner. These data suggest that this side-activity of GA could be explored for the treatment of prion-based diseases and other amyloid-based disorders. In this perspective, the potent antihypertensive activity of GA happens to be an annoying side-effect that could limit its use. In order to get rid of GA agonist activity at ?2-adrenergic receptors, we performed a structure-activity relationship study around GA based on changes of the chlorine positions on the benzene moiety and then on the modifications of the guanidine group. Hence, we identified the two derivatives 6 and 7 that still possess a potent antiprion activity but were totally devoid of any agonist activity at ?2-adrenergic receptors. Similarly to GA, 6 and 7 were also able to inhibit the protein folding activity of the ribosome (PFAR) which has been suggested to be involved in prion appearance/maintenance. Therefore, these two GA derivatives are worth being considered as drug candidates. PMID:25244284

Nguyen, Phu Hai; Hammoud, Hassan; Halliez, Sophie; Pang, Yanhong; Evrard, Justine; Schmitt, Martine; Oumata, Nassima; Bourguignon, Jean-Jacques; Sanyal, Suparna; Beringue, Vincent; Blondel, Marc; Bihel, Frédéric; Voisset, Cécile

2014-10-15

83

Weakly sheared active suspensions: Hydrodynamics, stability, and rheology  

NASA Astrophysics Data System (ADS)

We present a kinetic model for flowing active suspensions and analyze the behavior of a suspension subjected to a weak steady shear. Asymptotic solutions are sought in Deborah number expansions. At the leading order, we explore the steady states and perform their stability analysis. We predict the rheology of active systems including an activity thickening or thinning behavior of the apparent viscosity and a negative apparent viscosity depending on the particle type, flow alignment, and the anchoring conditions, which can be tested on bacterial suspensions. We find remarkable dualities that show that flow-aligning rodlike contractile (extensile) particles are dynamically and rheologically equivalent to flow-aligning discoid extensile (contractile) particles for both tangential and homeotropic anchoring conditions. Another key prediction of this work is the role of the concentration of active suspensions in controlling the rheological behavior: The apparent viscosity may decrease with the increase of the concentration.

Cui, Zhenlu

2011-03-01

84

A selective metabotropic glutamate receptor 7 agonist: Activation of receptor signaling via an allosteric site modulates stress parameters in vivo  

PubMed Central

Metabotropic glutamate receptor (mGluR) subtypes (mGluR1 to mGluR8) act as important pre- and postsynaptic regulators of neurotransmission in the CNS. These receptors consist of two domains, an extracellular region containing the orthosteric agonist site and a transmembrane heptahelical domain involved in G protein activation and recognition of several recently synthesized pharmacological modulators. The presynaptic receptor mGluR7 shows the highest evolutionary conservation within the family, but no selective pharmacological tool was known. Here we characterize an mGluR7-selective agonist, N,N?-dibenzhydrylethane-1,2-diamine dihydrochloride (AMN082), which directly activates receptor signaling via an allosteric site in the transmembrane domain. At transfected mammalian cells expressing mGluR7, AMN082 potently inhibits cAMP accumulation and stimulates GTP?S binding (EC50-values, 64-290 nM) with agonist efficacies comparable with those of l-2-amino-4-phosphonobutyrate (L-AP4) and superior to those of l-glutamate. AMN082 (?10 ?M) failed to show appreciable activating or inhibitory effects at other mGluR subtypes and selected ionotropic GluRs. Chimeric receptor studies position the binding site of AMN082 in the transmembrane region of mGluR7, and we demonstrate that this allosteric agonist has little, if any, effect on the potency of orthosteric ligands. Here we provide evidence for full agonist activity mediated by the heptahelical domain of family 3 G protein-coupled receptors (which have mGluR-like structure) that may lead to drug development opportunities. Further, AMN082 is orally active, penetrates the blood-brain barrier, and elevates the plasma stress hormones corticosterone and corticotropin in an mGluR7-dependent fashion. Therefore, AMN082 is a valuable tool for unraveling the role of mGluR7 in stress-related CNS disorders. PMID:16339898

Mitsukawa, Kayo; Yamamoto, Rina; Ofner, Silvio; Nozulak, Joachim; Pescott, Oliver; Lukic, Snezana; Stoehr, Natacha; Mombereau, Cedric; Kuhn, Rainer; McAllister, Kevin H.; van der Putten, Herman; Cryan, John F.; Flor, Peter J.

2005-01-01

85

The in vitro pharmacological profile of TD-5108, a selective 5-HT(4) receptor agonist with high intrinsic activity.  

PubMed

The in vitro pharmacological profile of TD-5108, a novel, selective 5-HT(4) receptor agonist, was compared to that of clinically efficacious gastroprokinetic 5-HT(4) receptor agonists. TD-5108 produced an elevation of cyclic adenosine monophosphate in human embryonic kidney 293 cells expressing the human recombinant 5-HT(4(c)) (h5-HT(4(c))) receptor (pEC(50) = 8.3) and 5-HT(4) receptor-mediated relaxation of the rat esophagus (pEC(50) = 7.9) and contraction of the guinea pig colon (pEC(50) = 7.9). In all in vitro assays, TD-5108 was a high intrinsic activity agonist, unlike tegaserod, mosapride, and cisapride which, in the majority of test systems, had lower intrinsic activity. TD-5108 had high affinity (pK (i) = 7.7) and selectivity (> or =25-fold) for h5-HT(4(c)) receptors over other biogenic amine receptors. TD-5108 was >500-fold selective over other 5-HT receptors (including h5-HT(2B) and h5-HT(3A)) and, at 3 microM, had no effect on human ether-à-go-go-related gene K+ channels. In conclusion, TD-5108 is a selective 5-HT(4) receptor agonist in vitro. The high intrinsic activity and preferential binding of TD-5108 to 5-HT4 over other 5-HT receptors may result in an improved clinical profile for the treatment of gastrointestinal disorders of reduced motility. PMID:18415081

Smith, J A M; Beattie, D T; Marquess, D; Shaw, J P; Vickery, R G; Humphrey, P P A

2008-07-01

86

Molecular basis for agonist selectivity and activation of the orphan BRS-3-receptor  

PubMed Central

Bombesin receptor subtype-3(BRS-3), a G protein-coupled orphan receptor, shares 51% identity with the mammalian bombesin(Bn) receptor for gastrin-releasing peptide(GRPR). There is increasing interest in BRS-3 because it is important in energy metabolism, glucose control,motility and tumor-growth. BRS-3 has low affinity for all Bn-related peptides, however, recently synthetic high-affinity agonists[D-Tyr6/D-Phe6,?Ala11,Phe13,Nle14]Bn-(6–14) were described, but they are nonselective for BRS-3 over other Bn-receptors. Based on these peptides, three BRS-3 selective-ligands were developed: peptide#2,[D-Tyr6(R)-Apa11,Phe13,Nle14]Bn(6–14); peptide#3,[D-Tyr6,(R)-Apa11,4Cl-Phe13,Nle14]Bn(6–14); peptide #4,Ac-Phe-Trp-Ala-His(tBzl)-Nip-Gly-Arg-NH2. Their molecular determinants of selectivity/high affinity for BRS-3 are unknown. To address this we used a chimeric/site-mutagenesis approach. Substitution of extracellular domain2(EC2) of BRS-3 by the comparable GRPR domain decreased 26-,4,0-fold affinity for peptides#4,3,2. Substitution of EC3 decreased affinity 4-,11-,0-fold affinity for peptides#2,3,4. Ten point mutations in the EC2 and adjacent transmembrane regions (TM2) 2 and 3 of BRS-3 were made. His107(EC2-BRS-3) for lysine(H107K)(EC2-GRPR), decreased affinity(25-,0-fold) for peptide#4,1; however it could not be activated by either peptide. Its combination with Val101(TM2),Gly112(EC2),Arg127(TM3) resulted in complete loss-of-affinity of peptide#4. Receptor-modeling showed that each of these residues face inward and are within 4Å of the binding-pocket. These results demonstrate [Val101,His107,Gly112,Arg127] in the EC2/adjacent upper TMs of BRS-3 are critical for the high BRS3-selectivity of peptide#4. His107 in EC2 is essential for BRS-3 activation, suggesting amino-aromatic ligand/receptor interactions with peptide#4 are critical for both binding/ activation. Furthermore, these result demonstrate that even though these three BRS-3 selective agonists were developed from the same template peptide,[D-Phe6,?Ala11,Phe13,Nle14]Bn-(6–14), their molecular determinants of selectivity/high affinity varied considerably. PMID:18006692

Gonzalez, Nieves; Hocart, Simon J.; Portal-Nunez, Sergio; Mantey, Samuel A.; Nakagawa, Tomoo; Zudaire, Enrique; Coy, David H.; Jensen, Robert T.

2008-01-01

87

Direct and Indirect 5-HT receptor agonists produce gender-specific effects on locomotor and vertical activity in C57 BL/6J mice  

PubMed Central

It is well established that the dopamine (DA) and serotonin (5-HT) systems have extensive and complex interactions. However, the effects of specific 5-HT receptor agonists on traditionally DA-related behaviors remain unclear. Our goal in these studies was to characterize the effects of 5-HT receptor agonists on measures of locomotor activity and vertical rearing. The SSRIs fluoxetine and citalopram produced significant decreases in locomotor activity and vertical rearing at the highest doses used with females significant more sensitive to citalopram. The 5-HT1A agonist 8-OH-DPAT and the 5-HT2C agonist MK 212 significantly decreased activity in both male and female mice, with females more sensitive to 8-OH-DPAT. In contrast, the 5-HT1B agonist RU 24969 and the 5-HT2A agonist DOI both increased activity, with DOI exhibiting differential effects with regard to sex. Finally, the 5-HT3 agonist SR 57227 produced significant locomotor increases only in female mice at the lowest dose. The results of these experiments define locomotor profiles of several 5-HT agonists in male and female C57BL/6J mice, providing a foundation for further explorations of 5-HT receptor effects on activity. PMID:19698737

Brookshire, Bethany R.; Jones, Sara R.

2009-01-01

88

Activated-like hopping transition in weakly vibrated granular media  

NASA Astrophysics Data System (ADS)

The slow dynamics of a weakly vibrated granular medium is investigated using a low-frequency forced torsion pendulum method. A loss factor peak is observed in the pendulum response (or the granular susceptibility) as a function of the vibration intensity or the forcing frequency. The position of the peak follows an Arrhenius-like behaviour and the data can be described as an activated hopping process. The peak can be seen as a vibration-induced glass-like transition between a low-? jammed phase and the high-? fluid-like phase.

D'Anna, G.; Gremaud, G.

2001-06-01

89

A novel natural Nrf2 activator with PPAR?-agonist (monascin) attenuates the toxicity of methylglyoxal and hyperglycemia.  

PubMed

Methylglyoxal (MG) is a toxic-glucose metabolite and a major precursor of advanced glycation endproducts (AGEs). MG has been reported to result in inflammation by activating receptor for AGEs (RAGE). We recently found that Monascus-fermented metabolite monascin acts as a novel natural peroxisome proliferator-activated receptor-? (PPAR?) agonist that improves insulin sensitivity. We investigated the metabolic, biochemical, and molecular abnormalities characteristic of type 2 diabetes in MG-treated Wistar rats treated with oral administration of monascin or rosiglitazone. Monascin (a novel PPAR? agonist) activated nuclear factor-erythroid 2-related factor 2 (Nrf2) and down-regulated hyperinsulinmia in oral glucose tolerance test (OGTT). Monascin was able to elevate glyoxalase-1 expression via activation of hepatic Nrf2, hence, resulting in MG metabolism to d-lactic acid and protected from AGEs production in MG-treated rats. Rosiglitazone did not activate Nrf2 nor glyoxalase expression to lower serum and hepatic AGEs levels. Monascin acts as a novel natural Nrf2 activator with PPAR?-agonist activity were confirmed by Nrf2 and PPAR? reporter assays in Hep G2 cells. These findings suggest that monascin acts as an anti-diabetic and anti-oxidative stress agent to a greater degree than rosiglitazone and thus may have therapeutic potential for the prevention of diabetes. PMID:23954466

Hsu, Wei-Hsuan; Lee, Bao-Hong; Chang, Yu-Ying; Hsu, Ya-Wen; Pan, Tzu-Ming

2013-11-01

90

BAY 41-2272, a soluble guanylate cyclase agonist, activates human mononuclear phagocytes  

PubMed Central

BACKGROUND AND PURPOSE Phagocyte function is critical for host defense against infections. Defects in phagocytic function lead to several primary immunodeficiencies characterized by early onset of recurrent and severe infections. In this work, we further investigated the effects of BAY 41-2272, a soluble guanylate cyclase (sGC) agonist, on the activation of human peripheral blood monocytes (PBM) and THP-1 cells. EXPERIMENTAL APPROACH THP-1 cells and PBM viability was evaluated by methylthiazoletetrazolium assay; reactive oxygen species production by lucigenin chemiluminescence; gene and protein expression of NAPDH oxidase components by qRT-PCR and Western blot analysis, respectively; phagocytosis and microbicidal activity by co-incubation, respectively, with zymosan and Escherichia coli; and cytokine release by elisa. KEY RESULTS BAY 41-2272, compared with the untreated group, increased spreading of monocytes by at least 35%, superoxide production by at least 50%, and gp91PHOX and p67PHOX gene expression 20 to 40 times, in both PBM and THP-1 cells. BAY 41-2272 also augmented phagocytosis of zymosan particles threefold compared with control, doubled microbicidal activity against E. coli and enhanced the release of TNF-? and IL-12p70 by both PBM and THP-1 cells. Finally, by inhibiting sGC with ODQ, we showed that BAY 41-2272-induced superoxide production and phagocytosis is not dependent exclusively on sGC activation. CONCLUSIONS AND IMPLICATIONS In addition to its ability to induce vasorelaxation and its potential application for therapy of vascular diseases, BAY 41-2272 was shown to activate human mononuclear phagocytes. Hence, it is a novel pro-inflammatory drug that may be useful for controlling infections in the immunocompromised host. PMID:22044316

Soeiro-Pereira, PV; Falcai, A; Kubo, CA; Oliveira-Junior, EB; Marques, OC; Antunes, E; Condino-Neto, A

2012-01-01

91

Agonist-evoked calcium entry in vascular smooth muscle cells requires IP 3 receptor-mediated activation of TRPC1  

Microsoft Academic Search

Transient receptor potential canonical (TRPC) proteins have been proposed to function as plasma membrane Ca2+ channels activated by store depletion and\\/or by receptor stimulation. However, their role in the increase in cytosolic Ca2+ activated by contractile agonists in vascular smooth muscle is not yet elucidated. The present study was designed to investigate the functional and molecular properties of the Ca2+

Khalid Tai; Marie-Christine Hamaide; Huguette Debaix; Philippe Gailly; Maurice Wibo; Nicole Morel

2008-01-01

92

Design, Synthesis, and Biological Evaluation of Novel Constrained meta-Substituted Phenyl Propanoic Acids as Peroxisome Proliferator-Activated Receptor r and Dual Agonists  

E-print Network

Acids as Peroxisome Proliferator-Activated Receptor r and Dual Agonists Young-Ger Suh,*, Nam-Jung Kim. Introduction Peroxisome proliferator-activated receptors (PPARsa ) regulate the lipid and glucose metabolism

Suh, Young-Ger

93

Did Weak-line Quasars Just Begin an Active Phase?  

NASA Astrophysics Data System (ADS)

Active Galactic Nuclei (AGN) are often defined by their prominent emission lines, and rare instances of AGN lacking strong emission features are often explained by the presence of a relativistically boosted radio jet (i.e., as for BL Lac objects). However, the SDSS has discovered a population of 80 high-redshift (z>2.2) radio-quiet quasars with weak emission lines (WLQs) not predicted by the standard orientation based model. Inclusive AGN selection approaches are now also revealing lower-redshift radio-quiet AGN lacking strong emission lines (around 100 objects to date), which are potential analogs to WLQs. Here, we describe our sample of low-redshift WLQ candidates, and we present follow-up multiwavelength observations for 26 objects. Our conclusion is WLQs likely have intrinsically weak broad emission line regions. Finally, we compare WLQs to accreting stellar mass black holes to explore the possibility that WLQs are in a short-lived evolutionary stage where quasar activity has only recently begun. Studying extreme examples of AGN like WLQs may lead to new insight into the formation of broad emission line regions in AGN. Support for this work was provided by a Netherlands Organization for Scientific Research (NWO) Vidi Fellowship.

Plotkin, Richard M.; Anderson, S. F.; Brandt, W. N.; Diamond-Stanic, A. M.; Fan, X.; MacLeod, C. L.; Markoff, S.; Schneider, D. P.; Shemmer, O.

2011-01-01

94

Review of the pleiotropic effects of peroxisome proliferator-activated receptor gamma agonists on platelet function.  

PubMed

The primary target receptor for thiazolidinediones (TZDs) or peroxisome proliferator-activated receptor gamma (PPARgamma) agonists is a transcription factor in the nucleus of adipocytes and other metabolically active cells, where they improve insulin sensitivity and glucose utilization. TZDs are also able to modify gene expression in macrophages, smooth muscle cells, and endothelial cells. Although PPARgamma is considered to be a nuclear receptor, enucleate platelets also highly express this receptor. The aim of this review is to present the current understanding of a direct or indirect effect of TZDs on platelet function. By means of a comprehensive literature search (January 1990-June 2006), publications were obtained that contained specific information about in vitro and in vivo effects of TZDs on platelet function. The effects were studied for different risk biochemical markers, i.e., proteins found to be elevated in the state of procoagulant inflammation and endothelial dysfunction. Improvement of platelet function was reported for all TZDs-troglitazone, pioglitazone, and rosiglitazone. The described effects included reduction of platelet aggregation, suppression of thrombin-induced protein kinase C-alpha and -beta activation, decrease in plasma P-selectin and platelet P-selectin expression, increase in nitric oxide production, inhibition of the Rho/Rho kinase pathway, and inhibition of tissue factor- and platelet-activating factor-induced morphological changes in macrophages. These findings appeared in parallel with reduction of the plasma concentrations of pro-inflammatory risk markers. TZDs seem to have a direct pleiotropic positive influence on platelet function and coagulation and may be helpful in treating the prothrombotic state observed in patients with type 2 diabetes and metabolic syndrome. PMID:17931049

Borchert, M; Schöndorf, T; Lübben, G; Forst, T; Pfützner, A

2007-10-01

95

The PPARalpha Agonist Fenofibrate Preserves Hippocampal Neurogenesis and Inhibits Microglial Activation After Whole-Brain Irradiation  

SciTech Connect

Purpose: Whole-brain irradiation (WBI) leads to cognitive impairment months to years after radiation. Numerous studies suggest that decreased hippocampal neurogenesis and microglial activation are involved in the pathogenesis of WBI-induced brain injury. The goal of this study was to investigate whether administration of the peroxisomal proliferator-activated receptor (PPAR) alpha agonist fenofibrate would prevent the detrimental effect of WBI on hippocampal neurogenesis. Methods and Materials: For this study, 129S1/SvImJ wild-type and PPARalpha knockout mice that were fed either regular or 0.2% wt/wt fenofibrate-containing chow received either sham irradiation or WBI (10-Gy single dose of {sup 137}Cs gamma-rays). Mice were injected intraperitoneally with bromodeoxyuridine to label the surviving cells at 1 month after WBI, and the newborn neurons were counted at 2 months after WBI by use of bromodeoxyuridine/neuronal nuclei double immunofluorescence. Proliferation in the subgranular zone and microglial activation were measured at 1 week and 2 months after WBI by use of Ki-67 and CD68 immunohistochemistry, respectively. Results: Whole-brain irradiation led to a significant decrease in the number of newborn hippocampal neurons 2 months after it was performed. Fenofibrate prevented this decrease by promoting the survival of newborn cells in the dentate gyrus. In addition, fenofibrate treatment was associated with decreased microglial activation in the dentate gyrus after WBI. The neuroprotective effects of fenofibrate were abolished in the knockout mice, indicating a PPARalpha-dependent mechanism or mechanisms. Conclusions: These data highlight a novel role for PPARalpha ligands in improving neurogenesis after WBI and offer the promise of improving the quality of life for brain cancer patients receiving radiotherapy.

Ramanan, Sriram [Department of Cancer Biology, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Brain Tumor Center of Excellence, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Kooshki, Mitra; Zhao Weiling [Brain Tumor Center of Excellence, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Department of Radiation Oncology, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Hsu, F.-C. [Department of Biostatistical Sciences, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Riddle, David R. [Brain Tumor Center of Excellence, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Department of Neurobiology and Anatomy, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Robbins, Mike E., E-mail: mrobbins@wfubmc.ed [Brain Tumor Center of Excellence, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Department of Radiation Oncology, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States)

2009-11-01

96

The glucagon-like peptide 1 receptor agonist enhances intrinsic peroxisome proliferator-activated receptor ? activity in endothelial cells.  

PubMed

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 PPAR? activation is involved in the GLP-1-mediated anti-inflammatory action on endothelial cells. When we treated HUVEC cells with 0.2ng/ml exendin-4, a GLP-1 receptor agonist, endogenous PPAR? transcriptional activity was significantly elevated, by approximately 20%, as compared with control cells. The maximum PPAR? activity enhancing effect of exendin-4 was observed 12h after the initiation of incubation with exendin-4. As H89, a PKA inhibitor, abolished GLP-1-induced PPAR? enhancement, the signaling downstream from GLP-1 cross-talk must have been involved in PPAR? activation. In conclusion, our results suggest that GLP-1 has the potential to induce PPAR? activity, partially explaining the anti-inflammatory effects of GLP-1 on endothelial cells. Cross-talk between GLP-1 signaling and PPAR? activation would have major impacts on treatments for patients at high risk for cardiovascular disease. PMID:25109805

Onuma, Hirohisa; Inukai, Kouichi; Kitahara, Atsuko; Moriya, Rie; Nishida, Susumu; Tanaka, Toshiaki; Katsuta, Hidenori; Takahashi, Kazuto; Sumitani, Yoshikazu; Hosaka, Toshio; Ishida, Hitoshi

2014-08-22

97

Polyacetylenes from Notopterygium incisum-New Selective Partial Agonists of Peroxisome Proliferator-Activated Receptor-Gamma  

PubMed Central

Peroxisome proliferator-activated receptor gamma (PPAR?) is a key regulator of glucose and lipid metabolism and therefore an important pharmacological target to combat metabolic diseases. Since the currently used full PPAR? agonists display serious side effects, identification of novel ligands, particularly partial agonists, is highly relevant. Searching for new active compounds, we investigated extracts of the underground parts of Notopterygium incisum, a medicinal plant used in traditional Chinese medicine, and observed significant PPAR? activation using a PPAR?-driven luciferase reporter model. Activity-guided fractionation of the dichloromethane extract led to the isolation of six polyacetylenes, which displayed properties of selective partial PPAR? agonists in the luciferase reporter model. Since PPAR? activation by this class of compounds has so far not been reported, we have chosen the prototypical polyacetylene falcarindiol for further investigation. The effect of falcarindiol (10 µM) in the luciferase reporter model was blocked upon co-treatment with the PPAR? antagonist T0070907 (1 µM). Falcarindiol bound to the purified human PPAR? receptor with a Ki of 3.07 µM. In silico docking studies suggested a binding mode within the ligand binding site, where hydrogen bonds to Cys285 and Glu295 are predicted to be formed in addition to extensive hydrophobic interactions. Furthermore, falcarindiol further induced 3T3-L1 preadipocyte differentiation and enhanced the insulin-induced glucose uptake in differentiated 3T3-L1 adipocytes confirming effectiveness in cell models with endogenous PPAR? expression. In conclusion, we identified falcarindiol-type polyacetylenes as a novel class of natural partial PPAR? agonists, having potential to be further explored as pharmaceutical leads or dietary supplements. PMID:23630612

Liu, Xin; Noha, Stefan M.; Malainer, Clemens; Kramer, Matthias P.; Cocic, Amina; Kunert, Olaf; Schinkovitz, Andreas; Heiss, Elke H.; Schuster, Daniela

2013-01-01

98

Effects of the peroxisome proliferator-activated receptor (PPAR)-? agonist GW501516 on bone and muscle in ovariectomized rats.  

PubMed

Estrogen deficiency promotes bone loss and skeletal muscle dysfunction. Peroxisome proliferator-activated receptors (PPARs) have 3 subtypes (?, ?, and ?). PPAR? agonists induce bone loss, whereas PPAR? agonists increase bone mass. Although PPAR? agonists are known to influence skeletal muscle metabolism, the skeletal effects are unsettled. This study investigated the musculoskeletal effects of the PPAR? agonist GW501516 in ovariectomized (OVX) rats. Female Sprague Dawley rats, 12 weeks of age, were allocated to a sham-operated group and 3 OVX groups; high-dose GW501516 (OVX-GW5), low-dose GW501516 (OVX-GW1), and a control group (OVX-CTR), respectively (n = 12 per group). Animals received GW501516 or vehicle (methylcellulose) daily for 4 months by gavage. Bone mineral density (BMD) was assessed by dual x-ray absorptiometry at the femur, spine, and whole body. Bone microarchitecture at the proximal tibia was assessed by microcomputed tomography, and dynamic histomorphometry was performed. Quadriceps muscle morphology and the relative expression of mitochondrial proteins were analyzed. Bone metabolism markers and metabolic markers were measured in plasma. After 4 months, the OVX-GW5 group displayed lower femoral BMD than OVX-CTR. Trabecular separation was higher in the GW-treated groups, compared with OVX-CTR. The OVX-GW5 group also exhibited lower cortical area fraction and a higher structure model index than OVX-CTR. These effects coincided with impaired bone formation in both GW groups. The OVX-GW5 group displayed elevated triglyceride levels and reduced adiponectin levels, whereas no effects on muscle morphology or mitochondrial gene expression appeared. In summary, the PPAR? agonist GW501516 negatively affected bone properties in OVX rats, whereas no effects were detected in skeletal muscle. PMID:24708238

Mosti, M P; Stunes, A K; Ericsson, M; Pullisaar, H; Reseland, J E; Shabestari, M; Eriksen, E F; Syversen, U

2014-06-01

99

NMDA receptor activation strengthens weak electrical coupling in mammalian brain.  

PubMed

Electrical synapses are formed by gap junctions and permit electrical coupling, which shapes the synchrony of neuronal ensembles. Here, we provide a direct demonstration of receptor-mediated strengthening of electrical coupling in mammalian brain. Electrical coupling in the inferior olive of rats was strengthened by activation of NMDA-type glutamate receptors (NMDARs), which were found at synaptic loci and at extrasynaptic loci 20-100 nm proximal to gap junctions. Electrical coupling was strengthened by pharmacological and synaptic activation of NMDARs, whereas costimulation of ionotropic non-NMDAR glutamate receptors transiently antagonized the effect of NMDAR activation. NMDAR-dependent strengthening (1) occurred despite increased input conductance, (2) induced Ca(2+)-influx microdomains near dendritic spines, (3) required activation of the Ca(2+)/calmodulin-dependent protein-kinase II, (4) was restricted to neurons that were weakly coupled, and (5) thus strengthened coupling, mainly between nonadjacent neurons. This provided a mechanism to expand the synchronization of rhythmic membrane potential oscillations by chemical neurotransmitter input. PMID:24656255

Turecek, Josef; Yuen, Genevieve S; Han, Victor Z; Zeng, Xiao-Hui; Bayer, K Ulrich; Welsh, John P

2014-03-19

100

Cerebral radioprotection by pentobarbital: Dose-response characteristics and association with GABA agonist activity  

SciTech Connect

Pentobarbital reduces cerebral radiation toxicity; however, the mechanism of this phenomenon remains unknown. As an anesthetic and depressant of cerebral metabolism, pentobarbital induces its effects on the central nervous system by stimulating the binding of gamma-aminobutyric acid (GABA) to its receptor and by inhibiting postsynaptic excitatory amino acid activity. The purpose of this study is to investigate the role of these actions as well as other aspects of the radioprotective activity of pentobarbital. Fischer 344 rats were separated into multiple groups and underwent two dose-response evaluations. In one set of experiments to examine the relationship of radioprotection to pentobarbital dose, a range of pentobarbital doses (0 to 75 mg/kg) were given intraperitoneally prior to a constant-level radiation dose (70 Gy). In a second series of experiments to determine the dose-response relationship of radiation protection to radiation dose, a range of radiation doses (10 to 90 Gy) were given with a single pentobarbital dose. Further groups of animals were used to evaluate the importance of the timing of pentobarbital administration, the function of the (+) and (-) isomers of pentobarbital, and the role of an alternative GABA agonist (diazepam). In addition, the potential protective effects of alternative methods of anesthesia (ketamine) and induction of cerebral hypometabolism (hypothermia) were examined. Enhancement of survival time from acute radiation injury due to high-dose single-fraction whole-brain irradiation was maximal with 60 mg/kg of pentobarbital, and occurred over the range of all doses examined between 30 to 90 Gy. Protection was seen only in animals that received the pentobarbital before irradiation. Administration of other compounds that enhance GABA binding (Saffan and diazepam) also significantly enhanced survival time.

Olson, J.J.; Friedman, R.; Orr, K.; Delaney, T.; Oldfield, E.H. (National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD (USA))

1990-05-01

101

Benzodiazepine modulation of partial agonist efficacy and spontaneously active GABA(A) receptors supports an allosteric model of modulation.  

PubMed

Benzodiazepines (BZDs) have been used extensively for more than 40 years because of their high therapeutic index and low toxicity. Although BZDs are understood to act primarily as allosteric modulators of GABA(A) receptors, the mechanism of modulation is not well understood. The applicability of an allosteric model with two binding sites for gamma-aminobutyric acid (GABA) and one for a BZD-like modulator was investigated. This model predicts that BZDs should enhance the efficacy of partial agonists. Consistent with this prediction, diazepam increased the efficacy of the GABA(A) receptor partial agonist kojic amine in chick spinal cord neurons. To further test the validity of the model, the effects of diazepam, flurazepam, and zolpidem were examined using wild-type and spontaneously active mutant alpha1(L263S)beta3gamma2 GABA(A) receptors expressed in HEK-293 cells. In agreement with the predictions of the allosteric model, all three modulators acted as direct agonists for the spontaneously active receptors. The results indicate that BZD-like modulators enhance the amplitude of the GABA response by stabilizing the open channel active state relative to the inactive state by less than 1 kcal, which is similar to the energy of stabilization conferred by a single hydrogen bond. PMID:15912137

Downing, Scott S; Lee, Yan T; Farb, David H; Gibbs, Terrell T

2005-08-01

102

Peroxisome proliferator-activated receptor ? agonist effect on rheumatoid arthritis: a randomized controlled trial  

PubMed Central

Introduction Rheumatoid arthritis (RA), a chronic inflammatory disease, is associated with insulin resistance. Experimental evidence indicates that the relationship between insulin resistance and inflammation is bidirectional: Inflammation promotes insulin resistance, and insulin resistance promotes inflammation. Therefore, we examined the hypothesis that pioglitazone, a thiazolidinedione peroxisome proliferator-activated receptor ? agonist, would decrease inflammation and disease activity and improve insulin resistance in patients with RA. Methods In a single-center, randomized, double-blind, placebo-controlled crossover study patients with RA (N?=?34) receiving stable therapy were randomized to also receive either pioglitazone 45 mg daily (n?=?17) or matching placebo (n?=?17) for eight weeks. This was followed by a four-week washout period and alternative treatment for eight weeks. Outcomes included change in Disease Activity Score in 28 joints (DAS28) score, individual components of the DAS28 score and homeostatic model assessment for insulin resistance (HOMA). Intention-to-treat analysis and linear mixed-effects models were used. Results Patients had a mean (±SD) age of 51 (±14.2) years, 82.4% were female and baseline DAS28 high-sensitivity C-reactive protein (DAS28-CRP) was 4.58 (±1.1) units. Addition of pioglitazone was associated with a 9.3% reduction (95% confidence interval (CI)?=?0.17% to 17.6%) in DAS28-CRP (P?=?0.046), but no significant change in DAS28 erythrocyte sedimentation rate (DAS28-ESR) (P?=?0.92). There was a 10.7mm (95% CI?=?0.4 to 20.9 mm) improvement in patient-reported global health (P?=?0.042), a 48.6% decrease (95% CI?=?27.6% to 63.5%) in CRP (P??0.05). Lower-extremity edema was more common during pioglitazone treatment (16%) than placebo (0%). Conclusion Addition of pioglitazone to RA therapy improves insulin resistance and modestly reduces RA disease activity measured by DAS28-CRP and two of its components, including patient-reported global health and CRP, but not DAS28-ESR or ESR. Trial registration NCT00763139 PMID:24020899

2013-01-01

103

A selective metabotropic glutamate receptor 7 agonist: activation of receptor signaling via an allosteric site modulates stress parameters in vivo.  

PubMed

Metabotropic glutamate receptor (mGluR) subtypes (mGluR1 to mGluR8) act as important pre- and postsynaptic regulators of neurotransmission in the CNS. These receptors consist of two domains, an extracellular region containing the orthosteric agonist site and a transmembrane heptahelical domain involved in G protein activation and recognition of several recently synthesized pharmacological modulators. The presynaptic receptor mGluR7 shows the highest evolutionary conservation within the family, but no selective pharmacological tool was known. Here we characterize an mGluR7-selective agonist, N,N'-dibenzhydrylethane-1,2-diamine dihydrochloride (AMN082), which directly activates receptor signaling via an allosteric site in the transmembrane domain. At transfected mammalian cells expressing mGluR7, AMN082 potently inhibits cAMP accumulation and stimulates GTPgammaS binding (EC50-values, 64-290 nM) with agonist efficacies comparable with those of L-2-amino-4-phosphonobutyrate (L-AP4) and superior to those of L-glutamate. AMN082 (< or = 10 microM) failed to show appreciable activating or inhibitory effects at other mGluR subtypes and selected ionotropic GluRs. Chimeric receptor studies position the binding site of AMN082 in the transmembrane region of mGluR7, and we demonstrate that this allosteric agonist has little, if any, effect on the potency of orthosteric ligands. Here we provide evidence for full agonist activity mediated by the heptahelical domain of family 3 G protein-coupled receptors (which have mGluR-like structure) that may lead to drug development opportunities. Further, AMN082 is orally active, penetrates the blood-brain barrier, and elevates the plasma stress hormones corticosterone and corticotropin in an mGluR7-dependent fashion. Therefore, AMN082 is a valuable tool for unraveling the role of mGluR7 in stress-related CNS disorders. PMID:16339898

Mitsukawa, Kayo; Yamamoto, Rina; Ofner, Silvio; Nozulak, Joachim; Pescott, Oliver; Lukic, Snezana; Stoehr, Natacha; Mombereau, Cedric; Kuhn, Rainer; McAllister, Kevin H; van der Putten, Herman; Cryan, John F; Flor, Peter J

2005-12-20

104

Opiate Agonists Activate Feeding in Limax: Comparison of In Vivo and In Vitro Effects  

Microsoft Academic Search

The neural control system for feeding in the terrestrial mollusc Limax maximus is modulated by at least two major families of peptides. Sequence homology between one of the peptides known to modulate Limax feeding and some members of the opioid peptide family suggested that opioid peptides might also modulate Limax feeding. Experiments with the mu agonist morphine and the kappa

M. Wong; K. Delaney; A. Gelperin

1991-01-01

105

Monoclonal Antibodies to Purified Muscarinic Receptor Display Agonist-Like Activity  

Microsoft Academic Search

Monoclonal antibody M-35, which immunoprecipitates native calf brain acetylcholine muscarinic receptor, mimics agonist stimulation of the intact guinea pig myometrium: the antibody, just like carbamoylcholine hydrochloride, causes a rise in intracellular cyclic GMP content, an inhibition of cyclic AMP accumulation due to prostacyclin, and induces uterine contractions. Another antibody, M-23, which reacts with the denatured muscarinic receptor, is devoid of

D. Leiber; S. Harbon; J.-G. Guillet; C. Andre; A. D. Strosberg

1984-01-01

106

Modulation of agonist responses at the A(1) adenosine receptor by an irreversible antagonist, receptor-G protein uncoupling and by the G protein activation state.  

PubMed

Potency and intrinsic activity of agonists depend on ligand structure, but are also regulated by receptor-G protein stoichiometry. A potential functional reserve in adenosine A(1) receptor-mediated G protein activation was investigated by stimulation of guanosine-5'-(gamma-[35S]thio)-triphosphate ([35S]GTPgammaS) binding by the full agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA) and the partial agonist 5'-deoxy-5'-methylthioadenosine (MeSA). Pretreatment of rat brain membranes with the irreversible antagonist 1-propyl-3-[3-[[4-(fluorosulfonyl)benzoyl]oxy]-propyl]-8-cyclopentylxanthine revealed no classical receptor reserve for either agonist. The functional significance of the G protein coupling state of the receptor and occupancy of G proteins by guanine nucleotides was assessed after partial uncoupling of receptor-G protein complexes with N-ethylmaleimide and in the presence of increasing GDP concentrations. Agonist EC(50) values in G protein activation were increased after NEM pretreatment and at higher GDP concentrations, and a decrease in the relative intrinsic activity of MeSA was observed. The shift of agonist concentration-response curves to the right, the decrease in maximal effects and the decrease in relative intrinsic activity of the partial agonist point to a functional reserve which has to be attributed to GDP-free receptor-G protein complexes. The mechanisms of action of FSCPX, NEM and GDP were fully consistent with the two-state model of receptor activation. The apparent reserve revealed by GDP reflects a shift from spontaneously active GDP-free receptor-G protein complexes (RG)(*), which can bind [35S]GTPgammaS, to (RG) occupied by GDP. The abundance of (RG)(*) is favored by agonists and by the absence of GDP. PMID:12234606

Lorenzen, Anna; Beukers, Margot W; van der Graaf, Piet Hein; Lang, Heidrun; van Muijlwijk-Koezen, Jacqueline; de Groote, Miriam; Menge, Wiro; Schwabe, Ulrich; IJzerman, Adriaan P

2002-10-15

107

Toll-Like Receptor 8 Agonist and Bacteria Trigger Potent Activation of Innate Immune Cells in Human Liver  

PubMed Central

The ability of innate immune cells to sense and respond to impending danger varies by anatomical location. The liver is considered tolerogenic but is still capable of mounting a successful immune response to clear various infections. To understand whether hepatic immune cells tune their response to different infectious challenges, we probed mononuclear cells purified from human healthy and diseased livers with distinct pathogen-associated molecules. We discovered that only the TLR8 agonist ssRNA40 selectively activated liver-resident innate immune cells to produce substantial quantities of IFN-?. We identified CD161Bright mucosal-associated invariant T (MAIT) and CD56Bright NK cells as the responding liver-resident innate immune cells. Their activation was not directly induced by the TLR8 agonist but was dependent on IL-12 and IL-18 production by ssRNA40-activated intrahepatic monocytes. Importantly, the ssRNA40-induced cytokine-dependent activation of MAIT cells mirrored responses induced by bacteria, i.e., generating a selective production of high levels of IFN-?, without the concomitant production of TNF-? or IL-17A. The intrahepatic IFN-? production could be detected not only in healthy livers, but also in HBV- or HCV-infected livers. In conclusion, the human liver harbors a network of immune cells able to modulate their immunological responses to different pathogen-associated molecules. Their ability to generate a strong production of IFN-? upon stimulation with TLR8 agonist opens new therapeutic opportunities for the treatment of diverse liver pathologies. PMID:24967632

Ussher, James E.; Sandalova, Elena; Tang, Xin-Zi; Tan-Garcia, Alfonso; To, Natalie; Hong, Michelle; Chia, Adeline; Gill, Upkar S.; Kennedy, Patrick T.; Tan, Kai Chah; Lee, Kang Hoe; De Libero, Gennaro; Gehring, Adam J.; Willberg, Christian B.; Klenerman, Paul; Bertoletti, Antonio

2014-01-01

108

mGluR7 undergoes rapid internalization in response to activation by the allosteric agonist AMN082.  

PubMed

The G-protein coupled receptor (GPCR) metabotropic glutamate receptor 7 (mGluR7) is widely expressed throughout the nervous system and is implicated in diverse physiological processes ranging from synaptic plasticity to neuroprotection. To date, unequivocally assigning specific functions to mGluR7 has been hampered by a lack of specific pharmacological tools, however, an mGluR7 specific allosteric agonist, AMN082, was recently discovered. Accumulating evidence indicates that in addition to G-protein activation, GPCRs trigger critical intracellular signalling cascades during agonist-induced internalization. Thus, to determine if AMN082 will be useful for evaluating signalling events related to mGluR7 internalization as well as receptor activation we have examined whether AMN082 induces mGluR7 endocytosis. Using an immunofluorescence assay we demonstrate that AMN082 induces robust internalization of mGluR7 overexpressed in dissociated hippocampal neurons. AMN082-induced mGluR7 internalization was resistant to inhibition by a competitive antagonist consistent with the distinct binding site of the allosteric agonist from the glutamate-binding pocket utilized by conventional orthosteric ligands. Finally, as an independent assay of receptor internalization we overexpressed N-terminal pHluorin-tagged mGluR7 in neurons, allowing live imaging of surface receptors in real time. AMN082 treatment produced a rapid loss of surface mGluR7 as indicated by decreased fluorescence confirming the ability of allosteric receptor activation to trigger mGluR7 endocytosis. Thus, AMN082 will be effective for investigating physiological processes related to both mGluR7 activation and internalization such as control of bidirectional plasticity at mossy fiber-st. lucidum interneuron synapses. PMID:16914173

Pelkey, Kenneth A; Yuan, Xiaoqing; Lavezzari, Gabriela; Roche, Katherine W; McBain, Chris J

2007-01-01

109

Opiate agonists activate feeding in Limax: comparison of in vivo and in vitro effects.  

PubMed

The neural control system for feeding in the terrestrial mollusc Limax maximus is modulated by at least two major families of peptides. Sequence homology between one of the peptides known to modulate Limax feeding and some members of the opioid peptide family suggested that opioid peptides might also modulate Limax feeding. Experiments with the mu agonist morphine and the kappa agonist U50,488H showed that the probability of feeding, but not meal size, was increased by morphine injection into intact animals, whereas the length of feeding motor program responses elicited from the isolated lip-brain preparation of Limax was augmented by U50,488H. The behavioral effect of morphine was blocked by naltrexone injection, whereas the physiological effect of U50,488H was blocked by naloxone. Factors that influence the behavioral and electrophysiological effects of opioids on mollusc feeding are discussed. PMID:1851015

Wong, M; Delaney, K; Gelperin, A

1991-02-01

110

Structure-activity relationship studies on cholecystokinin: Analogues with partial agonist activity  

SciTech Connect

In the present study, hepta- and octapeptide analogues of the C-terminal part of cholecystokinin, modified on the C-terminal phenylalanine residue, were synthesized. CCK analogues were prepared in which the peptide bond between aspartic acid and phenylalanine had or had not been modified and were lacking the C-terminal primary amide function. These CCK derivatives were able to cause full stimulation of amylase release from rat pancreatic acini but without a decrease in amylase release at supramaximal concentrations. There was a close relationship between the abilities of these derivatives to stimulate amylase release and their abilities to inhibit binding of {sup 125}I-BH-CCK-9 to CCK receptors on rat and guinea pig pancreatic acini. These CCK analogues were also able to recognize the guinea pig brain CCK receptors, some of them being particularly potent. The findings indicate that the aromatic ring of phenylalanine is important for the binding to brain and pancreatic CCK receptors, whereas the C-terminal primary amide function is not essential for the binding to pancreatic CCK receptors but is crucial for biological activity of rat pancreatic acini.

Galas, M.C.; Lignon, M.F.; Rodriguez, M.; Mendre, C.; Fulcrand, P.; Laur, J.; Martinez, J. (Centre de Pharmacologie-Endocrinologie, Montpellier (France))

1988-02-01

111

Decavanadate possesses ?-adrenergic agonist activity and a structural motif common with trans-? form of noradrenaline  

Microsoft Academic Search

Decavanadate, an inorganic polymer of vanadate, produced contraction of rat aortic rings at a relatively high concentration compared to phenylephrine, an agonist of a-adrenergic receptor. This effect was blocked by two known a-adrenergic receptor antagonists, prazosin and phenoxybenzamine. Decavanadate, formed by possible dimerization of V5 under acid conditions, possessed a structural feature of two pairs of unshared oxygen atoms at

B. V. Venkataraman; H. N. Ravishankar; Aparna V. S. Rao; P. Kalyani; G. Sharada; K. Namboodiri; B. Gahor; T. Ramasarma

1997-01-01

112

The PPAR? agonist rosiglitazone prevents cognitive impairment by inhibiting astrocyte activation and oxidative stress following pilocarpine-induced status epilepticus.  

PubMed

Epilepsy is commonly associated with cognitive impairment. Astrocyte activation and oxidative stress occur following seizures, and play a role in the pathological injury of epilepsy with cognitive impairment. The peroxisome proliferator-activated receptor gamma (PPAR?) has been shown to exhibit neuroprotective and antioxidative effects in CNS diseases. Thus, we hypothesized that rosiglitazone, a PPAR? agonist, would prevent cognitive impairment by inhibiting astrocyte activation and regulating glutathione (GSH) homeostasis after status epilepticus (SE). Using a lithium pilocarpine-induced SE model, we found that rosiglitazone significantly prevented cognitive impairment induced by SE, and potently inhibited astrocyte activation with maintenance of GSH homeostasis in the hippocampus after SE. These protective effects were significantly reversed by co-treatment with the PPAR? antagonist T0070907. These data suggest that rosiglitazone can improve cognitive impairment, and inhibit astrocyte activation and oxidative damage following SE. Rosiglitazone may be a promising agent for treatment of epilepsy involving SE-induced cognitive impairment. PMID:21915647

Hong, Sun; Xin, Yu; HaiQin, Wu; GuiLian, Zhang; Ru, Zhang; ShuQin, Zhan; HuQing, Wang; Li, Yao; Yun, Du

2012-06-01

113

Inhibition of T cell activation and autoimmune diabetes using a B cell surface-linked CTLA-4 agonist  

PubMed Central

CTL-associated antigen 4 (CTLA-4) engagement negatively regulates T cell activation and function and promotes immune tolerance. However, it has been difficult to explore the biology of selective engagement of CTLA-4 in vivo because CTLA-4 shares its ligands, B7-1 and B7-2, with CD28. To address this issue, we developed a Tg mouse expressing a single-chain, membrane-bound anti–CTLA-4 Ab (scFv) on B cells. B and T cells developed normally and exhibited normal phenotype in the steady state and after activation in these mice. However, B cells from scFv Tg+ mice (sc?CTLA4+) prevented T cell proliferation and cytokine production in mixed lymphocyte reactions. Additionally, mice treated with sc?CTLA4+ B cells had decreased T cell–dependent B cell Ab production and class switching in vivo after antigen challenge. Furthermore, expression of this CTLA-4 agonist protected NOD mice from spontaneous autoimmune diabetes. Finally, this disease prevention occurred in Treg-deficient NOD.B7-1/B7-2 double-knockout mice, suggesting that the effect of the CTLA-4 agonist directly attenuates autoreactive T cell activation, not Treg activation. Together, results from this study demonstrate that selective ligation of CTLA-4 attenuates in vivo T cell responses, prevents development of autoimmunity, and represents a novel immunotherapeutic approach for the induction and maintenance of peripheral tolerance. PMID:16886063

Fife, Brian T.; Griffin, Matthew D.; Abbas, Abul K.; Locksley, Richard M.; Bluestone, Jeffrey A.

2006-01-01

114

Design, synthesis and structure-activity relationships of azole acids as novel, potent dual PPAR alpha/gamma agonists.  

PubMed

The design, synthesis and structure-activity relationships of a novel series of N-phenyl-substituted pyrrole, 1,2-pyrazole and 1,2,3-triazole acid analogs as PPAR ligands are outlined. The triazole acid analogs 3f and 4f were identified as potent dual PPARalpha/gamma agonists both in binding and functional assays in vitro. The 3-oxybenzyl triazole acetic acid analog 3f showed excellent glucose and triglyceride lowering in diabetic db/db mice. PMID:19201606

Zhang, Hao; Ryono, Denis E; Devasthale, Pratik; Wang, Wei; O'Malley, Kevin; Farrelly, Dennis; Gu, Liqun; Harrity, Thomas; Cap, Michael; Chu, Cuixia; Locke, Kenneth; Zhang, Litao; Lippy, Jonathan; Kunselman, Lori; Morgan, Nathan; Flynn, Neil; Moore, Lisa; Hosagrahara, Vinayak; Zhang, Lisa; Kadiyala, Pathanjali; Xu, Carrie; Doweyko, Arthur M; Bell, Aneka; Chang, Chiehying; Muckelbauer, Jodi; Zahler, Robert; Hariharan, Narayanan; Cheng, Peter T W

2009-03-01

115

Peroxisome proliferator-activated receptor ? agonist suppresses human telomerase reverse transcriptase expression and aromatase activity in eutopic endometrial stromal cells from endometriosis  

PubMed Central

Objective To investigate the effect of peroxisome proliferator activated receptor ? (PPAR?) agonist on the cell proliferation properties and expression of human telomerase reverse transcriptase (hTERT) and aromatase in cultured endometrial stromal cell (ESC) from patients with endometriosis. Methods Human endometrial tissues were obtained from women with endometriosis and healthy women (controls) using endometrial biopsy. Isolated ESCs were cultured and the cell proliferation was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay and expression of hTERT, aromatase, and cyclooxygenase (COX)-2 by western blotting according to the addition of rosiglitazone (PPAR? agonist). Results We demonstrate that the cultured ESCs of endometriosis showed hTERT protein overexpression and increased cellular proliferation, which was inhibited by rosiglitazone, in a dose-dependent manner. At the same time, PPAR? agonist also inhibited aromatase and COX-2 expression, resulting in decreased prostaglandin E2 production in the ESCs of endometriosis. Conclusion This study suggests that PPAR? agonist plays an inhibitory role in the proliferative properties of eutopic endometrium with endometriosis by down-regulation of hTERT and COX-2 expression; this could be a new treatment target for endometriosis. PMID:23875162

Chang, Hye Jin; Lee, Jae Hoon; Kim, Mi Ran; Yoo, Jung Hyun

2013-01-01

116

TLR7/8 agonists activate a mild immune response in rabbits through TLR8 but not TLR7.  

PubMed

Toll-like receptors 7 (TLR7) and 8 (TLR8) recognize viral single-stranded RNA and small molecular weight agonists to activate anti-viral immune responses. TLR8s from different species have distinct ligand recognitions. For example, human TLR8 is responsive to ligand stimulation, but mouse and rat TLR8 are activated by small molecular weight agonists only in the presence of polyT-oligodeoxynucleotides. TLR7 and TLR8 have been reported to be absent and pseudogenized, respectively, in rabbit (Oryctolagus cuniculus). In this study, we detected the expression of rabbit (rab)TLR8 in immune-cell-associated tissues. Cell proliferation and cytokine expressions in rabbit splenocytes were induced by the TLR7/8 ligand but not by the TLR7 ligands, suggesting that rabTLR8 is functional but rabTLR7 is not. In rabbits, CL075, a TLR7/8 ligand, activated an antigen-specific antibody response, although one not as potent as aluminum salt or Freund's adjuvant. Nevertheless, CL075, alone or in combination with aluminum salt, generates fewer adverse effects than Freund's adjuvant at the injection sites. To further investigate the activation of rabTLR8, we cloned its cDNA. In cell-based assay, this rabTLR8 is activated by TLR7/8 ligand but not activated by TLR7 ligand. Upon stimulation the rabTLR8 had a lower activation compared to the activation of TLR8 from other species, except the mouse and rat TLR8s. Using different deletion and human-rabbit chimeric TLR8 expressing constructs, we showed that an extra peptide in the undefined region results in reduced activity of rabTLR8. These results provide a molecular basis for the mild activities of TLR7/8 ligands in rabbits, and suggest TLR7/8 agonists may provide safer immune stimuli in rabbits than in other non-rodent species. PMID:25131730

Lai, Chao-Yang; Liu, Yi-Ling; Yu, Guann-Yi; Maa, Ming-Chei; Leu, Tzeng-Horng; Xu, Congfeng; Luo, Yunping; Xiang, Rong; Chuang, Tsung-Hsien

2014-09-29

117

4-Hydroxydocosahexaenoic acid, a potent peroxisome proliferator-activated receptor {gamma} agonist alleviates the symptoms of DSS-induced colitis  

SciTech Connect

(5E,7Z,10Z,13Z,16Z,19Z)-4-Hydroxy-5,7,10,13,16,19-docosahexaenoic acid (4-OHDHA) is a potential agonist of peroxisome proliferator-activated receptor-{gamma} (PPAR{gamma}) and antidiabetic agent as has been previously reported. As PPAR{gamma} agonists may also have anti-inflammatory functions, in this study, we investigated whether 4-OHDHA has an inhibitory effect on expression of inflammatory genes in vitro and whether 4-OHDHA could relieve the symptoms of dextran sodium sulfate (DSS)-induced colitis in a murine model of inflammatory bowel disease. 4-OHDHA inhibited production of nitric oxide and expression of a subset of inflammatory genes including inducible nitric oxide synthase (Nos2/iNOS) and interleukin 6 (Il6) by lipopolysaccharide (LPS)-activated macrophages. In addition, 4-OHDHA-treated mice when compared to control mice not receiving treatment recovered better from the weight loss caused by DSS-induced colitis. Changes in disease activity index (DAI) of 4-OHDHA-treated mice were also more favorable than for control mice and were comparable with mice treated with a typical anti-inflammatory-drug, 5-aminosalichylic acid (5-ASA). These results suggest that 4-OHDHA has potentially clinically useful anti-inflammatory effects mediated by suppression of inflammatory gene expression.

Yamamoto, Keiko [Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543 (Japan); Ninomiya, Yuichi; Iseki, Mioko [Division of Translational Research, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama 350-1241 (Japan); Nakachi, Yutaka; Kanesaki-Yatsuka, Yukiko [Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama 350-1241 (Japan); Yamanoue, Yu; Itoh, Toshimasa [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Nishii, Yasuho [Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama 350-1241 (Japan); Petrovsky, Nikolai [Diabetes and Endocrinology, Flinders Medical Centre, Bedford Park, SA 5042 (Australia); Okazaki, Yasushi [Division of Translational Research, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama 350-1241 (Japan); Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama 350-1241 (Japan)], E-mail: okazaki@saitama-med.ac.jp

2008-03-14

118

Conicasterol E, a small heterodimer partner sparing farnesoid X receptor modulator endowed with a pregnane X receptor agonistic activity, from the marine sponge Theonella swinhoei.  

PubMed

We report the isolation and pharmacological characterization of conicasterol E isolated from the marine sponge Theonella swinhoei. Pharmacological characterization of this steroid in comparison to CDCA, a natural FXR ligand, and 6-ECDCA, a synthetic FXR agonist generated by an improved synthetic strategy, and rifaximin, a potent PXR agonist, demonstrated that conicasterol E is an FXR modulator endowed with PXR agonistic activity. Conicasterol E induces the expression of genes involved in bile acids detoxification without effect on the expression of small heterodimer partner (SHP), thus sparing the expression of genes involved in bile acids biosynthesis. The relative positioning in the ligand binding domain of FXR, explored through docking calculations, demonstrated a different spatial arrangement for conicasterol E and pointed to the presence of simultaneous and efficient interactions with the receptor. In summary, conicasterol E represents a FXR modulator and PXR agonist that might hold utility in treatment of liver disorders. PMID:22126372

Sepe, Valentina; Ummarino, Raffaella; D'Auria, Maria Valeria; Chini, Maria Giovanna; Bifulco, Giuseppe; Renga, Barbara; D'Amore, Claudio; Debitus, Cécile; Fiorucci, Stefano; Zampella, Angela

2012-01-12

119

Neuron-released oligomeric ?-synuclein is an endogenous agonist of TLR2 for paracrine activation of microglia  

PubMed Central

Abnormal aggregation of ?-synuclein and sustained microglial activation are important contributors to the pathogenic processes in Parkinson's disease. However, the relationship between disease-associated protein aggregation and microglia-mediated neuroinflammation remains unknown. Here, using a combination of in silico, in vitro, and in vivo approaches, we show that extracellular ?-synuclein released from neuronal cells is an endogenous agonist for toll-like receptor 2 (TLR2), which activates inflammatory responses in microglia. TLR2 ligand activity of ?-synuclein is conformation-sensitive; only specific types of oligomer can interact with and activate TLR2. This paracrine interaction between neuron-released oligomeric ?-synuclein and TLR2 in microglia suggests that both of these proteins are novel therapeutic targets for modification of neuroinflammation in Parkinson's disease and related neurological diseases. PMID:23463005

Kim, Changyoun; Ho, Dong-Hwan; Suk, Ji-Eun; You, Sungyong; Michael, Sarah; Kang, Junghee; Lee, Sung Joong; Masliah, Eliezer; Hwang, Daehee; Lee, He-Jin; Lee, Seung-Jae

2014-01-01

120

Site Specificity of Agonist and Second Messenger-Activated Kinases for Somatostatin Receptor Subtype 2A (Sst2A) Phosphorylation  

PubMed Central

Somatostatin receptor subtype 2A (sst2A) mediates many of the endocrine and neuronal actions of somatostatin and is the target of somatostatin analogs in cancer therapy. As with many G-protein-coupled receptors, agonist stimulation causes sst2A receptor desensitization and internalization, events that require receptor phosphorylation. Furthermore, heterologous receptor activation of protein kinase C (PKC) also increases sst2A receptor phosphorylation and internalization. Here we analyzed a series of sst2A receptor mutants biochemically to identify residues in the receptor carboxyl terminus that were phosphorylated upon agonist stimulation, and we then generated four phosphorylation-sensitive antibodies to those residues. Once the selectivity of each antibody for its phosphorylated and nonphosphorylated target sequence was determined, the phospho-site-specific antibodies were used to demonstrate that somatostatin treatment of Chinese hamster ovary (CHO) cells expressing the wild type sst2A receptor increased phosphorylation on five residues in the receptor C terminus: Ser341, Ser343, Ser348, Thr353, and Thr354. Phorbol 12-myristate 13-acetate (PMA) increased receptor phosphorylation only on Ser343. Inhibition of PKC blocked PMA but not somatostatin stimulation, showing that different kinases catalyzed Ser343 phosphorylation. In contrast, somatostatin-stimulated sst2A receptor phosphorylation was inhibited by knockdown of G-protein coupled receptor kinase-2 with siRNA. Somatostatin increased sst2A receptor phosphorylation on the same five residues in GH4C1 pituitary cells as in CHO cells. However, PMA stimulated sst2A receptor phosphorylation on both Ser343 and Ser348 in GH4C1 cells. These results characterize the complex pattern of sst2A receptor phosphorylation by agonist and second messenger-activated kinases for the first time and indicate that cell type-specific regulation of sst2A receptor phosphorylation occurs. PMID:19389921

Liu, Qisheng; Bee, Mark S.; Schonbrunn, Agnes

2009-01-01

121

Activation of the gut calcium-sensing receptor by peptide agonists reduces rapid elevation of plasma glucose in response to oral glucose load in rats.  

PubMed

The calcium-sensing receptor (CaSR) is expressed in various tissues, including the gastrointestinal tract. To investigate the role of gut CaSR on glycemic control, we examined whether single oral administration of CaSR agonist peptides affected the glycemic response in rats. Glucose tolerance tests were performed under oral or duodenal administration of various CaSR agonist peptides (?Glu-Cys, protamine, and poly-d-lysine hydrobromide) in conscious rats. Involvement of CaSR was determined by using a CaSR antagonist. Signaling pathways underlying CaSR agonist-modified glycemia were investigated using gut hormone receptor antagonists. The gastric emptying rate after the administration of CaSR agonist peptides was measured by the phenol red recovery method. Oral and duodenal administration of CaSR agonist peptides attenuated glycemic responses under the oral glucose tolerance test, but the administration of casein did not. The promotive effect on glucose tolerance was weakened by luminal pretreatment with a CaSR antagonist. Treatment with a 5-HT3 receptor antagonist partially diminished the glucose-lowering effect of peptides. Furthermore, the gastric emptying rate was decreased by duodenal administration of CaSR agonist peptides. These results demonstrate that activation of the gut CaSR by peptide agonists promotes glucose tolerance in conscious rats. 5-HT3 receptor and the delayed gastric emptying rate appear to be involved in the glucose-lowering effect of CaSR agonist peptides. Thus, activation of gut CaSR by dietary peptides reduces glycemic responses so that gut CaSR may be a potential target for the improvement of postprandial glycemia. PMID:24812056

Muramatsu, Maya; Hira, Tohru; Mitsunaga, Arimi; Sato, Eri; Nakajima, Shingo; Kitahara, Yoshiro; Eto, Yuzuru; Hara, Hiroshi

2014-06-15

122

Peroxiredoxin 6 phosphorylation and subsequent phospholipase A2 activity are required for agonist-mediated activation of NADPH oxidase in mouse pulmonary microvascular endothelium and alveolar macrophages.  

PubMed

Peroxiredoxin 6 (Prdx6), a bifunctional enzyme with glutathione peroxidase and phospholipase A2 (PLA(2)) activities, participates in the activation of NADPH oxidase 2 (NOX2) in neutrophils, but the mechanism for this effect is not known. We now demonstrate that Prdx6 is required for agonist-induced NOX2 activation in pulmonary microvascular endothelial cells (PMVEC) and that the effect requires the PLA(2) activity of Prdx6. Generation of reactive oxygen species (ROS) in response to angiotensin II (Ang II) or phorbol 12-myristate 13-acetate was markedly reduced in perfused lungs and isolated PMVEC from Prdx6 null mice. Rac1 and p47(phox), cytosolic components of NOX2, translocated to the endothelial cell membrane after Ang II treatment in wild-type but not Prdx6 null PMVEC. MJ33, an inhibitor of Prdx6 PLA(2) activity, blocked agonist-induced PLA(2) activity and ROS generation in PMVEC by >80%, whereas inhibitors of other PLA(2)s were ineffective. Transfection of Prx6 null cells with wild-type and C47S mutant Prdx6, but not with mutants of the PLA(2) active site (S32A, H26A, and D140A), "rescued" Ang II-induced PLA(2) activity and ROS generation. Ang II treatment of wild-type cells resulted in phosphorylation of Prdx6 and its subsequent translocation from the cytosol to the cell membrane. Phosphorylation as well as PLA(2) activity and ROS generation were markedly reduced by the MAPK inhibitor, U0126. Thus, agonist-induced MAPK activation leads to Prdx6 phosphorylation and translocation to the cell membrane, where its PLA(2) activity facilitates assembly of the NOX2 complex and activation of the oxidase. PMID:21262967

Chatterjee, Shampa; Feinstein, Sheldon I; Dodia, Chandra; Sorokina, Elena; Lien, Yu-Chin; Nguyen, Su; Debolt, Kris; Speicher, David; Fisher, Aron B

2011-04-01

123

Peroxiredoxin 6 Phosphorylation and Subsequent Phospholipase A2 Activity Are Required for Agonist-mediated Activation of NADPH Oxidase in Mouse Pulmonary Microvascular Endothelium and Alveolar Macrophages*  

PubMed Central

Peroxiredoxin 6 (Prdx6), a bifunctional enzyme with glutathione peroxidase and phospholipase A2 (PLA2) activities, participates in the activation of NADPH oxidase 2 (NOX2) in neutrophils, but the mechanism for this effect is not known. We now demonstrate that Prdx6 is required for agonist-induced NOX2 activation in pulmonary microvascular endothelial cells (PMVEC) and that the effect requires the PLA2 activity of Prdx6. Generation of reactive oxygen species (ROS) in response to angiotensin II (Ang II) or phorbol 12-myristate 13-acetate was markedly reduced in perfused lungs and isolated PMVEC from Prdx6 null mice. Rac1 and p47phox, cytosolic components of NOX2, translocated to the endothelial cell membrane after Ang II treatment in wild-type but not Prdx6 null PMVEC. MJ33, an inhibitor of Prdx6 PLA2 activity, blocked agonist-induced PLA2 activity and ROS generation in PMVEC by >80%, whereas inhibitors of other PLA2s were ineffective. Transfection of Prx6 null cells with wild-type and C47S mutant Prdx6, but not with mutants of the PLA2 active site (S32A, H26A, and D140A), “rescued” Ang II-induced PLA2 activity and ROS generation. Ang II treatment of wild-type cells resulted in phosphorylation of Prdx6 and its subsequent translocation from the cytosol to the cell membrane. Phosphorylation as well as PLA2 activity and ROS generation were markedly reduced by the MAPK inhibitor, U0126. Thus, agonist-induced MAPK activation leads to Prdx6 phosphorylation and translocation to the cell membrane, where its PLA2 activity facilitates assembly of the NOX2 complex and activation of the oxidase. PMID:21262967

Chatterjee, Shampa; Feinstein, Sheldon I.; Dodia, Chandra; Sorokina, Elena; Lien, Yu-Chin; Nguyen, Su; Debolt, Kris; Speicher, David; Fisher, Aron B.

2011-01-01

124

Phenylacetic acid derivatives as hPPAR agonists.  

PubMed

Beginning with the weakly active lead structure 1, a new series of hPPAR agonists was developed. In vivo glucose and triglyceride lowering activity was obtained by homologation and oxamination to 3, then conversion to substituted benzisoxazoles 4 and 5. Further manipulation afforded benzofurans 6 and 7. Compound 7 was of comparable potency as a glucose and triglyceride lowering agent in insulin resistant rodents to BRL 49653. PMID:12657263

Santini, Conrad; Berger, Gregory D; Han, Wei; Mosley, Ralph; MacNaul, Karen; Berger, Joel; Doebber, Thomas; Wu, Margaret; Moller, David E; Tolman, Richard L; Sahoo, Soumya P

2003-04-01

125

A ?-Arrestin-Biased Agonist of the Parathyroid Hormone Receptor (PTH1R) Promotes Bone Formation Independent of G Protein Activation  

PubMed Central

About 40% of the therapeutic agents in use today exert their effects through seven-transmembrane receptors (7TMRs). When activated by ligands, these receptors trigger two pathways that independently transduce signals to the cell: one through heterotrimeric GTP-binding proteins (G proteins) and one through ?-arrestins; so-called biased agonists can selectively activate these distinct pathways. Here, we investigate selective activation of these pathways through the use of a biased agonist for the type 1 parathyroid hormone (PTH)–PTH-related protein receptor (PTH1R), (D-Trp12, Tyr34)-PTH(7–34) (PTH-?arr), which activates ?-arrestin but not classic G protein signaling. In mice, PTH-?arr induces anabolic bone formation, as does the nonselective agonist PTH (1–34), which activates both mechanisms. In ?-arrestin2–null mice, the increase in bone mineral density evoked by PTH(1–34) is attenuated and that stimulated by PTH-?arr is ablated. The ?-arrestin2–dependent pathway contributes primarily to trabecular bone formation and does not stimulate bone resorption. These results show that a biased agonist selective for the ?-arrestin pathway can elicit a response in vivo distinct from that elicited by nonselective agonists. Ligands with these properties may form the basis for improved 7TMR-directed pharmacologic agents with enhanced therapeutic specificity. PMID:20368153

Gesty-Palmer, Diane; Flannery, Pat; Yuan, Ling; Corsino, Leonor; Spurney, Robert; Lefkowitz, Robert J.; Luttrell, Louis M.

2010-01-01

126

MBX-102/JNJ39659100, a Novel Non-TZD Selective Partial PPAR-? Agonist Lowers Triglyceride Independently of PPAR-? Activation  

PubMed Central

MBX-102/JNJ-39659100 (MBX-102) is a selective, partial PPAR-? agonist that lowers glucose in the absence of some of the side effects, such as weight gain and edema, that are observed with the TZDs. Interestingly MBX-102 also displays pronounced triglyceride lowering in preclinical rodent models and in humans. Although in vitro reporter gene studies indicated that MBX-102 acid is a highly selective PPAR-? agonist that lacks PPAR-? activity, we sought to determine if PPAR-? activation in vivo could possibly contribute to the triglyceride lowering abilities of MBX-102. In vivo studies using ZDF and ZF rats demonstrated that MBX-102 lowered plasma triglycerides. However in ZF rats, MBX-102 had no effect on liver weight or on hepatic expression levels of PPAR-? target genes. Further in vitro studies in primary human hepatocytes supported these findings. Finally, the ability of MBX-102 to lower triglycerides was maintained in PPAR-? knockout mice, unambiguously establishing that the triglyceride lowering effect of MBX-102 is PPAR-? independent. The in vivo lipid lowering abilities of MBX-102 are therefore mediated by an alternate mechanism which is yet to be determined. PMID:19404482

Chandalia, Apurva; Clarke, Holly J.; Clemens, L. Edward; Pandey, Bindu; Vicena, Vic; Lee, Paul; Lavan, Brian E.; Gregoire, Francine M.

2009-01-01

127

Identification of isosilybin a from milk thistle seeds as an agonist of peroxisome proliferator-activated receptor gamma.  

PubMed

Peroxisome proliferator-activated receptor gamma (PPAR?) is a key regulator of glucose and lipid metabolism. Agonists of this nuclear receptor are used in the treatment of type 2 diabetes and are also studied as a potential treatment of other metabolic diseases, including nonalcoholic fatty liver disease. Silymarin, a concentrated phenolic mixture from milk thistle (Silybum marianum) seeds, is used widely as a supportive agent in the treatment of a variety of liver diseases. In this study, the PPAR? activation potential of silymarin and its main constituents was investigated. Isosilybin A (3) caused transactivation of a PPAR?-dependent luciferase reporter in a concentration-dependent manner. This effect could be reversed upon co-treatment with the PPAR? antagonist T0070907. In silico docking studies suggested a binding mode for 3 distinct from that of the inactive silymarin constituents, with one additional hydrogen bond to Ser342 in the entrance region of the ligand-binding domain of the receptor. Hence, isosilybin A (3) has been identified as the first flavonolignan PPAR? agonist, suggesting its further investigation as a modulator of this nuclear receptor. PMID:24597776

Pferschy-Wenzig, Eva-Maria; Atanasov, Atanas G; Malainer, Clemens; Noha, Stefan M; Kunert, Olaf; Schuster, Daniela; Heiss, Elke H; Oberlies, Nicholas H; Wagner, Hildebert; Bauer, Rudolf; Dirsch, Verena M

2014-04-25

128

Repeated morphine treatment-mediated hyperalgesia, allodynia and spinal glial activation are blocked by co-administration of a selective cannabinoid receptor type-2 agonist  

PubMed Central

Spinal glial activation has been implicated in sustained morphine-mediated paradoxical pain sensitization. Since activation of glial CB2 cannabinoid receptors attenuates spinal glial activation in neuropathies, we hypothesized that CB2 agonists may also attenuate sustained morphine–mediated spinal glial activation and pain sensitization. Our data indicate that co-administration of a CB2-selective agonist (AM 1241) attenuates morphine (intraperitoneal; twice daily; 6 days)-mediated thermal hyperalgesia and tactile allodynia in rats. A CB2 (AM 630) but not a CB1 (AM 251) antagonist mitigated this effect. AM 1241 co-treatment also attenuated spinal astrocyte and microglial marker and pro-inflammatory mediator (IL-1?, TNF?) immunoreactivities in morphine-treated rats, suggesting that CB2 agonists may be useful to prevent the neuroinflammatory consequences of sustained morphine treatment. PMID:22285397

Tumati, Suneeta; Largent-Milnes, Tally M; Keresztes, Attila; Ren, Jiyang; Roeske, William R; Vanderah, Todd W.; Varga, Eva V

2012-01-01

129

In Silico Design for Adenosine Monophosphate-Activated Protein Kinase Agonist from Traditional Chinese Medicine for Treatment of Metabolic Syndromes  

PubMed Central

Adenosine monophosphate-activated protein kinase (AMPK) acts as a master mediator of metabolic homeostasis. It is considered as a significant millstone to treat metabolic syndromes including obesity, diabetes, and fatty liver. It can sense cellular energy or nutrient status by switching on the catabolic pathways. Investigation of AMPK has new findings recently. AMPK can inhibit cell growth by the way of autophagy. Thus AMPK has become a hot target for small molecular drug design of tumor inhibition. Activation of AMPK must undergo certain extent change of the structure. Through the methods of structure-based virtual screening and molecular dynamics simulation, we attempted to find out appropriate small compounds from the world's largest TCM Database@Taiwan that had the ability to activate the function of AMPK. Finally, we found that two TCM compounds, eugenyl_beta-D-glucopyranoside and 6-O-cinnamoyl-D-glucopyranose, had the qualification to be AMPK agonist. PMID:24899913

Tang, Hsin-Chieh

2014-01-01

130

The benzodiazepine diazepam potentiates responses of ?1?2?2 ?-aminobutyric acid type A receptors activated by either ?-aminobutyric acid or allosteric agonists  

PubMed Central

Background The ?-aminobutyric acid type A receptor is target for several anesthetics, anticonvulsants, anxiolytics and sedatives. Neurosteroids, barbiturates and etomidate both potentiate responses to ?-aminobutyric acid (GABA) and allosterically activate the receptor. We examined the ability of a benzodiazepine, diazepam, to potentiate responses to allosteric agonists. Methods The ?-aminobutyric acid type A receptors were expressed in human embryonic kidney 293 cells, and studied using whole-cell and single-channel patch clamp. The receptors were activated by the orthosteric agonist GABA, and allosteric agonists pentobarbital, etomidate and alfaxalone. Results Diazepam is equally potent at enhancing responses to orthosteric and allosteric agonists. Diazepam EC50s were 25±4, 26±6, 33±6, and 26±3 nM for receptors activated by GABA, pentobarbital, etomidate, and alfaxalone, respectively (mean±S.D., 5–6 cells at each condition). Mutations to the benzodiazepine-binding site (?1(H101C), ?2(R144C), ?2(R197C)) reduced or removed potentiation for all agonists, and an inverse agonist at the benzodiazepine site reduced responses to all agonists. Single-channel data elicited by GABA demonstrate that in the presence of 1 ?M diazepam the prevalence of the longest open-time component is increased from 13±7 (mean±S.D., n=5 patches) to 27±8 % (n=3 patches) and the rate of channel closing is decreased from 129±28 s?1 to 47±6 s?1 (mean±S.D.) Conclusions We conclude that benzodiazepines do not act by enhancing affinity of the orthosteric site for GABA but rather by increasing channel gating efficacy. The results also demonstrate the presence of significant interactions between allosteric activators and potentiators, raising a possibility of effects on dosage requirements or changes in side effects. PMID:23407108

Li, Ping; Eaton, Megan M.; Steinbach, Joe Henry; Akk, Gustav

2013-01-01

131

The oxidative stress mediator 4-hydroxynonenal is an intracellular agonist of the nuclear receptor peroxisome proliferator-activated receptor-?/? (PPAR?/?)  

PubMed Central

Liver insufficiency and damage is a major cause of death and disease worldwide and may result from exposure to environmental toxicants, specific combinations or dosages of pharmaceuticals and microbial metabolites. The generation of reactive intermediates, in particular 4-hydroxynonenal (4-HNE), is a common event in liver damage caused by a variety of hepatotoxic drugs and solvents. The peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that are involved in the transcriptional regulation of lipid metabolism as well as other biological functions. Importantly, we have observed that the PPAR?/??/? mouse is more susceptible to chemically-induced hepatotoxicity than its wildtype counterpart, and our objective in this study was to elucidate the mechanism(s) by which PPAR?/? confers protection to hepatocytes. We hypothesized that PPAR?/? plays a protective role by responding to toxic lipids and altering gene expression accordingly. In support, oxidized-VLDL and constituents including 13-S-hydroxyoctadeca-dienoic acid (13(S)-HODE) and 4-HNE are PPAR?/? ligands. A structure-activity relationship was established where 4-HNE and 4-hydroperoxynonenal (4-HpNE) enhanced the activity of the PPAR?/? subtype while 4-hyroxy-hexenal (4-HHE), 4-oxo-2-Nonenal (4-ONE), and trans-4,5-epoxy-2(E)-decenal did not activate this receptor. Increasing PPAR?/? activity with a synthetic agonist decreased sensitivity of hepatocytes to 4-HNE and other toxic agents, whereas inhibition of this receptor had the opposite result. Gene expression microarray analysis identified several important PPAR?/?-regulated detoxification enzymes involved in 4-HNE metabolism that are regulated at the transcript level. This research established 4-HNE as an endogenous modulator of PPAR?/? activity and raises the possibility that agonists of this nuclear receptor may be utilized to prevent or treat liver disease associated with oxidative damage. PMID:17382197

Coleman, Jeffrey D.; Prabhu, K. Sandeep; Thompson, Jerry T.; Reddy, P. Sreenivasula; Peters, Jeffrey M.; Peterson, Blake R.; Reddy, C. Channa; Vanden Heuvel, John P.

2007-01-01

132

Exposure of MC4R to agonist in the endoplasmic reticulum stabilizes an active conformation of the receptor that does not desensitize.  

PubMed

Melanocortin-4 receptor (MC4R) is a G protein-coupled receptor expressed in neurons of the hypothalamus where it regulates food intake. MC4R responds to an agonist, ?-melanocyte-stimulating hormone (?-MSH) and to an antagonist/inverse agonist, agouti-related peptide (AgRP), which are released by upstream neurons. Binding to ?-MSH leads to stimulation of receptor activity and suppression of food intake, whereas AgRP has opposite effects. MC4R cycles constantly between the plasma membrane and endosomes and undergoes agonist-mediated desensitization by being routed to lysosomes. MC4R desensitization and increased AgRP expression are thought to decrease the effectiveness of MC4R agonists as an antiobesity treatment. In this study, ?-MSH, instead of being delivered extracellularly, is targeted to the endoplasmic reticulum (ER) of neuronal cells and cultured hypothalamic neurons. We find that the ER-targeted agonist associates with MC4R at this location, is transported to the cell surface, induces constant cAMP and AMP kinase signaling at maximal amplitude, abolishes desensitization of the receptor, and promotes both cell-surface expression and constant signaling by an obesity-linked MC4R variant, I316S, that otherwise is retained in the ER. Formation of the MC4R/agonist complex in the ER stabilizes the receptor in an active conformation that at the cell surface is insensitive to antagonism by AgRP and at the endosomes is refractory to routing to the lysosomes. The data indicate that targeting agonists to the ER can stabilize an active conformation of a G protein-coupled receptor that does not become desensitized, suggesting a target for therapy. PMID:24248383

Granell, Susana; Molden, Brent M; Baldini, Giulia

2013-12-01

133

GLP-1 Receptor Agonists  

MedlinePLUS

... GLP-1 Receptor Agonists Share: Fact Sheet GLP-1 Receptor Agonists May, 2012 Download PDFs English Espanol ... too high or too low. What are GLP-1 receptor agonist medicines? GLP-1 receptor agonist medicines, ...

134

A Pepducin Derived from the Third Intracellular Loop of FPR2 Is a Partial Agonist for Direct Activation of This Receptor in Neutrophils But a Full Agonist for Cross-Talk Triggered Reactivation of FPR2  

PubMed Central

We recently described a novel receptor cross-talk mechanism in neutrophils, unique in that the signals generated by the PAF receptor (PAFR) and the ATP receptor (P2Y2R) transfer formyl peptide receptor 1 (FPR1) from a desensitized (non-signaling) state back to an actively signaling state (Forsman H et al., PLoS One, 8:e60169, 2013; Önnheim K, et al., Exp Cell Res, 323?209, 2014). In addition to the G-protein coupled FPR1, neutrophils also express the closely related receptor FPR2. In this study we used an FPR2 specific pepducin, proposed to work as an allosteric modulator at the cytosolic signaling interface, to determine whether the cross-talk pathway is utilized also by FPR2. The pepducin used contains a fatty acid linked to a peptide sequence derived from the third intracellular loop of FPR2, and it activates as well as desensensitizes this receptor. We now show that neutrophils desensitized with the FPR2-specific pepducin display increased cellular responses to stimulation with PAF or ATP. The secondary PAF/ATP induced response was sensitive to FPR2-specific inhibitors, disclosing a receptor cross-talk mechanism underlying FPR2 reactivation. The pepducin induced an activity in naïve cells similar to that of a conventional FPR2 agonist, but with lower potency (partial efficacy), meaning that the pepducin is a partial agonist. The PAF- or ATP-induced reactivation was, however, much more pronounced when neutrophils had been desensitized to the pepducin as compared to cells desensitized to conventional agonists. The pepducin should thus in this respect be classified as a full agonist. In summary, we demonstrate that desensitized FPR2 can be transferred back to an actively signaling state by receptor cross-talk signals generated through PAFR and P2Y2R, and the difference in agonist potency with respect to pepducin-induced direct receptor activation and cross-talk reactivation of FPR2 puts the concept of functional selectivity in focus. PMID:25303226

Gabl, Michael; Winther, Malene; Skovbakke, Sarah Line; Bylund, Johan; Dahlgren, Claes; Forsman, Huamei

2014-01-01

135

Peroxisome Proliferator-Activated Receptor Agonist Design Bull. Korean Chem. Soc. 2011, Vol. 32, No. 1 201 DOI 10.5012/bkcs.2011.32.1.201  

E-print Network

Peroxisome Proliferator-Activated Receptor Agonist Design Bull. Korean Chem. Soc. 2011, Vol. 32, No. 1 201 DOI 10.5012/bkcs.2011.32.1.201 Pharmacophore Identification for Peroxisome Proliferator November 15, 2010 Peroxisome proliferator-activated receptors (PPARs) are members of nuclear receptors

Lee, Keun Woo

136

KCNQ (Kv7) potassium channel activators as bronchodilators: combination with a ?2-adrenergic agonist enhances relaxation of rat airways.  

PubMed

KCNQ (Kv7 family) potassium (K(+)) channels were recently found in airway smooth muscle cells (ASMCs) from rodent and human bronchioles. In the present study, we evaluated expression of KCNQ channels and their role in constriction/relaxation of rat airways. Real-time RT-PCR analysis revealed expression of KCNQ4 > KCNQ5 > KCNQ1 > KCNQ2 > KCNQ3, and patch-clamp electrophysiology detected KCNQ currents in rat ASMCs. In precision-cut lung slices, the KCNQ channel activator retigabine induced a concentration-dependent relaxation of small bronchioles preconstricted with methacholine (MeCh; EC50 = 3.6 ± 0.3 ?M). Bronchoconstriction was also attenuated in the presence of two other structurally unrelated KCNQ channel activators: zinc pyrithione (ZnPyr; 1 ?M; 22 ± 7%) and 2,5-dimethylcelecoxib (10 ?M; 24 ± 8%). The same three KCNQ channel activators increased KCNQ currents in ASMCs by two- to threefold. The bronchorelaxant effects of retigabine and ZnPyr were prevented by inclusion of the KCNQ channel blocker XE991. A long-acting ?2-adrenergic receptor agonist, formoterol (10 nM), did not increase KCNQ current amplitude in ASMCs, but formoterol (1-1,000 nM) did induce a time- and concentration-dependent relaxation of rat airways, with a notable desensitization during a 30-min treatment or with repetitive treatments. Coadministration of retigabine (10 ?M) with formoterol produced a greater peak and sustained reduction of MeCh-induced bronchoconstriction and reduced the apparent desensitization observed with formoterol alone. Our findings support a role for KCNQ K(+) channels in the regulation of airway diameter. A combination of a ?2-adrenergic receptor agonist with a KCNQ channel activator may improve bronchodilator therapy. PMID:24441871

Brueggemann, Lioubov I; Haick, Jennifer M; Neuburg, Samantha; Tate, Shawn; Randhawa, Devjit; Cribbs, Leanne L; Byron, Kenneth L

2014-03-15

137

?-Lactotensin derived from bovine ?-lactoglobulin exhibits anxiolytic-like activity as an agonist for neurotensin NTS(2) receptor via activation of dopamine D(1) receptor in mice.  

PubMed

?-Lactotensin (His-Ile-Arg-Leu) is a bioactive peptide derived from bovine milk ?-lactoglobulin, acting as a natural agonist for neurotensin receptors. We found that ?-lactotensin exhibited anxiolytic-like activity in an elevated plus-maze test after its intraperitoneal (i.p.) administration in mice. ?-Lactotensin was also orally active. The anxiolytic-like activity of ?-lactotensin after i.p. administration was blocked by levocabastine, an antagonist for the neurotensin NTS(2) receptor. ?-Lactotensin had anxiolytic-like activity in wild-type but not Ntsr2-knockout mice. ?-Lactotensin increased intracellular Ca(2+) flux in glial cells derived from wild-type mice but not Ntsr2 knockout mice. These results suggest that ?-lactotensin acts as an NTS(2) receptor agonist having anxiolytic-like activity. The anxiolytic-like activity of ?-lactotensin was also blocked by SCH23390 and SKF83566, antagonists for dopamine D(1) receptor, but not by raclopride, an antagonist for D(2) receptor. Taken together, ?-lactotensin may exhibit anxiolytic-like activity via NTS(2) receptor followed by D(1) receptor. PMID:21895659

Hou, I-Ching; Suzuki, Chihiro; Kanegawa, Norimasa; Oda, Ayako; Yamada, Ayako; Yoshikawa, Masaaki; Yamada, Daisuke; Sekiguchi, Masayuki; Wada, Etsuko; Wada, Keiji; Ohinata, Kousaku

2011-11-01

138

Peroxisome proliferator-activated receptor ? agonists inhibit T helper type 1 (Th1) and Th17 responses in experimental allergic encephalomyelitis  

PubMed Central

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 PPAR?, ? and ? agonists inhibit CNS inflammation and demyelination in the EAE model of MS. In this study we show that the PPAR? agonists GW501516 and L165041 ameliorate MOGp35-55-induced EAE in C57BL/6 mice by blocking interferon (IFN)-? and interleukin (IL)-17 production by T helper type 1 (Th1) and Th17 cells. The inhibition of EAE by PPAR? 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 PPAR? agonists modulate Th1 and Th17 responses in EAE and suggest their use in the treatment of MS and other autoimmune diseases. PMID:20406305

Kanakasabai, Saravanan; Chearwae, Wanida; Walline, Crystal C; Iams, Wade; Adams, Suzanne M; Bright, John J

2010-01-01

139

Peroxisome proliferator-activated receptor delta agonists inhibit T helper type 1 (Th1) and Th17 responses in experimental allergic encephalomyelitis.  

PubMed

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 PPARgamma, alpha and delta agonists inhibit CNS inflammation and demyelination in the EAE model of MS. In this study we show that the PPARdelta agonists GW501516 and L165041 ameliorate MOGp35-55-induced EAE in C57BL/6 mice by blocking interferon (IFN)-gamma and interleukin (IL)-17 production by T helper type 1 (Th1) and Th17 cells. The inhibition of EAE by PPARdelta 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 PPARdelta agonists modulate Th1 and Th17 responses in EAE and suggest their use in the treatment of MS and other autoimmune diseases. PMID:20406305

Kanakasabai, Saravanan; Chearwae, Wanida; Walline, Crystal C; Iams, Wade; Adams, Suzanne M; Bright, John J

2010-08-01

140

The inverse agonist propranolol confers no corticosteroid-sparing activity in mild-to-moderate persistent asthma.  

PubMed

The murine asthma model shows that switching off airway ?2 receptors with an inverse agonist may confer anti-inflammatory effects as well as corticosteroid-sparing activity. We have assessed for any corticosteroid-sparing effects of propranolol, an inverse agonist, added to low-dose inhaled corticosteroid (ICS) compared with higher dose ICS. A randomized double-blind placebo-controlled cross-over trial in mild-to-moderate persistent asthmatic patients was performed. After a run-in (2 weeks) on hydrofluoroalkane-beclometasone dipropionate (HFA-BDP) at 100 ?g/day (HFA-BDP100), patients received randomized treatments (4 weeks) with propranolol at 80 mg/day plus HFA-BDP at 100 ?g/day compared with placebo plus HFA-BDP at 400 ?g/day (HFA-BDP400). Propranolol was up-titrated to 80 mg/day over the initial 2 weeks. Tiotropium was co-administered until 5 days before each histamine challenge (the primary outcome). Sixteen patients completed the study [mean age, 38 years; forced expiratory volume in 1 s (FEV1), 86.4%; histamine provocative concentration causing a 20% fall in FEV1 (PC20), 1.39 mg/ml; ICS dose, 406 ?g/day]. Histamine PC20 was unchanged by adding propranolol to HFA-BDP100 compared with baseline (HFA-BDP100) {0.17 doubling dilution (dd) difference [95% confidence interval (CI): -0.58 to 0.92]}, but there was a significant improvement with HFA-BDP400 compared with both baseline [1.05 dd (95% CI: 0.43-1.66); P=0.02], and propranolol+HFA-BDP100 [0.88 dd (95% CI: 0.45-1.30); P=0.006]. Significant improvements were also observed with HFA-BDP400 for exhaled nitric oxide, blood eosinophils, serum eosinophilic cationic protein and asthma quality-of-life questionnaire symptoms compared with propranolol+HFA-BDP100. Salbutamol recovery post-challenge was partially blunted by propranolol (median prolongation 5 min; P=0.002). Domiciliary evening FEV1 also fell with propranolol+HFA-BDP100 [mean reduction from baseline 0.22 litres (95% CI: 0.10-0.34); P=0.012], whereas Asthma Control Questionnaire remained unchanged. In conclusion, the inverse agonist propranolol produced no improvements when given with low-dose ICS, whereas further significant improvements in airway hyper-responsiveness and inflammation were demonstrated with higher dose ICS. Thus, propranolol does not confer corticosteroid-sparing activity in persistent asthma. PMID:24938324

Anderson, William J; Short, Philip M; Williamson, Peter A; Manoharan, Arvind; Lipworth, Brian J

2014-12-01

141

Dual Peroxisome Proliferator-Activated Receptor ?/? Agonist GFT505 Improves Hepatic and Peripheral Insulin Sensitivity in Abdominally Obese Subjects  

PubMed Central

OBJECTIVE The development of new insulin sensitizers is an unmet need for the treatment of type 2 diabetes. We investigated the effect of GFT505, a dual peroxisome proliferator–activated receptor (PPAR)-?/? agonist, on peripheral and hepatic insulin sensitivity. RESEARCH DESIGN AND METHODS Twenty-two abdominally obese insulin-resistant males (homeostasis model assessment of insulin resistance >3) were randomly assigned in a randomized crossover study to subsequent 8-week treatment periods with GFT505 (80 mg/day) or placebo, followed by a two-step hyperinsulinemic-euglycemic insulin clamp with a glucose tracer to calculate endogenous glucose production (EGP). The primary end point was the improvement in glucose infusion rate (GIR). Gene expression analysis was performed on skeletal muscle biopsy specimens. RESULTS GFT505 improved peripheral insulin sensitivity, with a 21% (P = 0.048) increase of the GIR at the second insulin infusion period. GFT505 also enhanced hepatic insulin sensitivity, with a 44% (P = 0.006) increase of insulin suppression of EGP at the first insulin infusion period. Insulin-suppressed plasma free fatty acid concentrations were significantly reduced on GFT505 treatment (0.21 ± 0.07 vs. 0.27 ± 0.11 mmol/L; P = 0.006). Neither PPAR? nor PPAR? target genes were induced in skeletal muscle, suggesting a liver-targeted action of GFT505. GFT505 significantly reduced fasting plasma triglycerides (?21%; P = 0.003) and LDL cholesterol (?13%; P = 0.0006), as well as liver enzyme concentrations (?-glutamyltranspeptidase: ?30.4%, P = 0.003; alanine aminotransferase: ?20.5%, P = 0.004). There was no safety concern or any indication of PPAR? activation with GFT505. CONCLUSIONS The dual PPAR?/? agonist GFT505 is a liver-targeted insulin-sensitizer that is a promising drug candidate for the treatment of type 2 diabetes and nonalcoholic fatty liver disease. PMID:23715754

Cariou, Bertrand; Hanf, Remy; Lambert-Porcheron, Stephanie; Zair, Yassine; Sauvinet, Valerie; Noel, Benoit; Flet, Laurent; Vidal, Hubert; Staels, Bart; Laville, Martine

2013-01-01

142

Pharmacological profile of DA-6886, a novel 5-HT4 receptor agonist to accelerate colonic motor activity in mice.  

PubMed

DA-6886, the gastrointestinal prokinetic benzamide derivative is a novel 5-HT4 receptor agonist being developed for the treatment of constipation-predominant irritable bowel syndrome (IBS-C). The purpose of this study was to characterize in vitro and in vivo pharmacological profile of DA-6886. We used various receptor binding assay, cAMP accumulation assay, organ bath experiment and colonic transit assay in normal and chemically constipated mice. DA-6886 exhibited high affinity and selectivity to human 5-HT4 receptor splice variants, with mean pKi of 7.1, 7.5, 7.9 for the human 5-HT4a, 5-HT4b and 5-HT4d, respectively. By contrast, DA-6886 did not show significant affinity for several receptors including dopamine D2 receptor, other 5-HT receptors except for 5-HT2B receptor (pKi value of 6.2). The affinity for 5-HT4 receptor was translated into functional agonist activity in Cos-7 cells expressing 5-HT4 receptor splice variants. Furthermore, DA-6886 induced relaxation of the rat oesophagus preparation (pEC50 value of 7.4) in a 5-HT4 receptor antagonist-sensitive manner. The evaluation of DA-6886 in CHO cells expressing hERG channels revealed that it inhibited hERG channel current with an pIC50 value of 4.3, indicating that the compound was 1000-fold more selective for the 5-HT4 receptor over hERG channels. In the normal ICR mice, oral administration of DA-6886 (0.4 and 2mg/kg) resulted in marked stimulation of colonic transit. Furthermore, in the loperamide-induced constipation mouse model, 2mg/kg of DA-6886 significantly improved the delay of colonic transit, similar to 10mg/kg of tegaserod. Taken together, DA-6886 is a highly potent and selective 5-HT4 receptor agonist to accelerate colonic transit in mice, which might be therapeutic agent having a favorable safety profile in the treatment of gastrointestinal motor disorders such as IBS-C and chronic constipation. PMID:24769304

Lee, Min Jung; Cho, Kang Hun; Park, Hyun Min; Sung, Hyun Jung; Choi, Sunghak; Im, Weonbin

2014-07-15

143

Definition of the molecular and cellular mechanisms underlying the tissue-selective agonist/antagonist activities of selective estrogen receptor modulators.  

PubMed

The term selective estrogen receptor modulators describes a group of pharmaceuticals that function as estrogen receptor (ER) agonists in some tissues but that oppose estrogen action in others. Although the name for this class of drugs has been adopted only recently, the concept is not new, as compounds exhibiting tissue-selective ER agonist/antagonist properties have been around for nearly 40 years. What is new is the idea that it may be possible to capitalize on the paradoxical activities of these drugs and develop them as target organ-selective ER agonists for the treatment of osteoporosis and other estrogenopathies. This realization has provided the impetus for research in this area, the progress of which is discussed in this review. PMID:12017549

McDonnell, Donald P; Connor, Caroline E; Wijayaratne, Ashini; Chang, Ching-Yi; Norris, John D

2002-01-01

144

Literary reading activities of good and weak students: A think aloud study  

Microsoft Academic Search

In this study we examined how good and weak students of literature interact with short literary stories. We focused on differences\\u000a in the use of cognitive and affective reading activities, and in the extent to which good and weak students adapt their activities\\u000a to (parts of) the story they are reading.\\u000a \\u000a 19 Dutch tenth-grade students from 8 classes participated in

Tanja Janssen; Martine Braaksma; Gert Rijlaarsdam

2006-01-01

145

CORRELATION OF THE ANTICHOLINESTERASE ACTIVITY OF A SERIES OF ORGANOPHOSPHATES WITH THEIR ABILITY TO COMPETE WITH AGONIST BINDING TO MUSCARINIC RECEPTORS  

EPA Science Inventory

Some compounds that inhibit acetylcholinesterase (ACHE) activity compete directly with quinuclidinyl benzilate (QNB) binding, a muscarinic antagonist which binds to all subtypes equally, and with cis-methyldioxolane (CD), an agonist that binds with high affinity to the M2 subtype...

146

Non-conventional synchronization of weakly coupled active oscillators  

NASA Astrophysics Data System (ADS)

We present a new type of self-sustained vibrations in the fundamental physical model covering a broad area of applications from wave generation in radiophysics and nonlinear optics to the heart muscle contraction and eyesight disorder in biophysics. Such a diversity of applications is due to the universal physical phenomenon of synchronization. Previous studies of this phenomenon, originating from Huygens famous observation, are based mainly on the model of two weakly coupled Van der Pol oscillators and usually deal with their synchronization in the regimes close to nonlinear normal modes (NNMs). In this work, we show for the first time that, in the important case of threshold excitation, an alternative synchronization mechanism can develop when the conventional synchronization becomes impossible. We identify this mechanism as an appearance of dynamic attractor with the complete periodic energy exchange between the oscillators, which is the dissipative analogue of highly intensive beats in a conservative system. This type of motion is therefore opposite to the NNM-type synchronization with no energy exchange by definition. The analytical description of these vibrations employs the concept of Limiting Phase Trajectories (LPTs) introduced by one of the authors earlier for conservative systems. Finally, within the LPT approach, we describe the transition from the complete energy exchange between the oscillators to the energy localization mostly on one of the two oscillators. The localized mode is an attractor in the range of model parameters wherein the LPT as well as the in-phase and out-of-phase NNMs become unstable.

Manevitch, L. I.; Kovaleva, M. A.; Pilipchuk, V. N.

2013-03-01

147

A GPBAR1 (TGR5) Small Molecule Agonist Shows Specific Inhibitory Effects on Myeloid Cell Activation In Vitro and Reduces Experimental Autoimmune Encephalitis (EAE) In Vivo  

PubMed Central

GPBAR1 is a G protein-coupled receptor that is activated by certain bile acids and plays an important role in the regulation of bile acid synthesis, lipid metabolism, and energy homeostasis. Recent evidence suggests that GPBAR1 may also have important effects in reducing the inflammatory response through its expression on monocytes and macrophages. To further understand the role of GPBAR1 in inflammation, we generated a novel, selective, proprietary GPBAR1 agonist and tested its effectiveness at reducing monocyte and macrophage activation in vitro and in vivo. We have used this agonist, together with previously described agonists to study agonism of GPBAR1, and shown that they can all induce cAMP and reduce TLR activation-induced cytokine production in human monocytes and monocyte-derived macrophages in vitro. Additionally, through the usage of RNA sequencing (RNA-Seq), we identified a select set of genes that are regulated by GPBAR1 agonism during LPS activation. To further define the in vivo role of GPBAR1 in inflammation, we assessed GPBAR1 expression and found high levels on circulating mouse monocytes. Agonism of GPBAR1 reduced LPS-induced cytokine production in mouse monocytes ex vivo and serum cytokine levels in vivo. Agonism of GPBAR1 also had profound effects in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis, where monocytes play an important role. Mice treated with the GPBAR1 agonist exhibited a significant reduction in the EAE clinical score which correlated with reduced monocyte and microglial activation and reduced trafficking of monocytes and T cells into the CNS. These data confirm the importance of GPBAR1 in controlling monocyte and macrophage activation in vivo and support the rationale for selective agonists of GPBAR1 in the treatment of inflammatory diseases. PMID:24967665

Lewis, Nuruddeen D.; Patnaude, Lori A.; Pelletier, Josephine; Souza, Donald J.; Lukas, Susan M.; King, F. James; Hill, Jonathan D.; Stefanopoulos, Dimitria E.; Ryan, Kelli; Desai, Sudha; Skow, Donna; Kauschke, Stefan G.; Broermann, Andre; Kuzmich, Daniel; Harcken, Christian; Hickey, Eugene R.; Modis, Louise K.

2014-01-01

148

SNC 80, a selective, nonpeptidic and systemically active opioid delta agonist.  

PubMed

The present study has investigated the pharmacology of SNC 80, a nonpeptidic ligand proposed to be a selective delta agonist in vitro and in vivo. SNC 80 was potent in producing inhibition of electrically induced contractions of mouse vas deferens, but not in inhibiting contractions of the guinea pig isolated ileum (IC50 values of 2.73 nM and 5457 nM, respectively). The delta selective antagonist ICI 174,864 (1 microM) and the mu selective antagonist CTAP (1 microM) produced 236- and 1.9-fold increases, respectively, in the SNC 80 IC50 value in the mouse vas deferens. SNC 80 preferentially competed against sites labeled by [3H]naltrindole (delta receptors) rather than against those labeled by [3H]DAMGO (mu receptors) or [3H]U69, 593 kappa receptors) in mouse whole-brain assays. The ratios of the calculated Ki values for SNC 80 at mu/delta and kappa/delta sites were 495- and 248-fold, respectively, which indicates a significant degree of delta selectivity for this compound in radioligand binding assays. SNC 80 produced dose- and time-related antinociception in the mouse warm-water tail-flick test after i.c.v., i.th. and i.p. administration. The calculated A50 values (and 95% C.I.) for SNC 80 administered i.c.v., i.th. and i.p. were 104.9 (63.7-172.7) nmol, 69 (51.8-92.1) nmol and 57 (44.5-73.1) mg/kg, respectively. The i.c.v. administration of SNC 80 also produced dose- and time-related antinociception in the hot-plate test, with a calculated A50 value (and 95% C.I.) of 91.9 (60.3-140.0) nmol.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7714789

Bilsky, E J; Calderon, S N; Wang, T; Bernstein, R N; Davis, P; Hruby, V J; McNutt, R W; Rothman, R B; Rice, K C; Porreca, F

1995-04-01

149

Glucagon-like peptide-1 receptor agonist activation ameliorates venous thrombosis-induced arteriovenous fistula failure in chronic kidney disease.  

PubMed

High shear stress that develops in the arteriovenous fistula of chronic kidney diseases (CKD) may increase H2O2 and thromboxane A2 (TXA2) release, thereby exacerbating endothelial dysfunction, thrombosis, and neointimal hyperplasia. We investigated whether glucagon-like peptide-1 receptor agonist/exendin-4, a potentially cardiovascular protective agent, could improve TXA2-induced arteriovenous fistula injury in CKD. TXA2 administration to H2O2-exposed human umbilical vein endothelial cells increased apoptosis, senescence, and detachment; these phenotypes were associated with the downregulation of phosphorylated endothelial nitric oxide synthase/heme oxygenase-1 (eNOS/HO-1) signalling. Exendin-4 reduced H2O2/TXA2-induced endothelial injury via inhibition of apoptosis-related mechanisms and restoration of phosphorylated eNOS/HO-1 signalling. Male Wistar rats subjected to right common carotid artery-external jugular vein anastomosis were treated with exendin-4 via cervical implant osmotic pumps for 16-42 days. High shear stress induced by the arteriovenous fistula significantly increased venous haemodynamics, blood and tissue H2O2 and TXB2 levels, macrophage/monocyte infiltration, fibrosis, proliferation, and adhesion molecule-1 expression. Apoptosis was also increased due to NADPH oxidase gp91 activation and mitochondrial Bax translocation in the proximal end of the jugular vein of CKD rats. Exendin-4-treatment of rats with CKD led to the restoration of normal endothelial morphology and correction of arteriovenous fistula function. Exendin-4 treatment or thromboxane synthase gene deletion in CKD mice markedly reduced ADP-stimulated platelet adhesion to venous endothelium, and prevented venous occlusion in FeCl3-injured vessels by upregulation of HO-1. Together, these data reveal that the use of glucagon-like peptide-1 receptor agonists is an effective strategy for treatment of CKD-induced arteriovenous fistula failure. PMID:25030617

Chien, C-T; Fan, S-C; Lin, S-C; Kuo, C-C; Yang, C-H; Yu, T-Y; Lee, S-P; Cheng, D-Y; Li, P-C

2014-11-01

150

The G Protein-Biased ?-Opioid Receptor Agonist RB-64 Is Analgesic with a Unique Spectrum of Activities In Vivo.  

PubMed

The hypothesis that functionally selective G protein-coupled receptor (GPCR) agonists may have enhanced therapeutic benefits has revitalized interest for many GPCR targets. In particular, although ?-opioid receptor (KOR) agonists are analgesic with a low risk of dependence and abuse, their use is limited by a propensity to induce sedation, motor incoordination, hallucinations, and dysphoria-like states. Several laboratories have produced a body of work suggesting that G protein-biased KOR agonists might be analgesic with fewer side effects. Although that has been an intriguing hypothesis, suitable KOR-selective and G protein-biased agonists have not been available to test this idea. Here we provide data using a G protein-biased agonist, RB-64 (22-thiocyanatosalvinorin A), which suggests that KOR-mediated G protein signaling induces analgesia and aversion, whereas ?-arrestin-2 signaling may be associated with motor incoordination. Additionally, unlike unbiased KOR agonists, the G protein-biased ligand RB-64 does not induce sedation and does not have anhedonia-like actions, suggesting that a mechanism other than G protein signaling mediates these effects. Our findings provide the first evidence for a highly selective and G protein-biased tool compound for which many, but not all, of the negative side effects of KOR agonists can be minimized by creating G protein-biased KOR agonists. PMID:25320048

White, Kate L; Robinson, J Elliott; Zhu, Hu; DiBerto, Jeffrey F; Polepally, Prabhakar R; Zjawiony, Jordan K; Nichols, David E; Malanga, C J; Roth, Bryan L

2015-01-01

151

[Design and synthesis of peroxisome proliferator-activated receptor (PPAR) delta agonists and its implication to the driving force to elicit PPAR delta selectivity].  

PubMed

A series of 3-(4-alkoxypheny)propanoic acid derivatives was prepared as candidate peroxisome proliferator-activated receptor (PPAR) delta-selective agonists, based on our previously discovered potent human PPARalpha/delta dual agonist TIPP-401 as a lead compound. Structure-activity relationship studies clearly indicated the importance of the chain length of the alkoxy group at the 4-position, and the n-butoxy compound exhibited the most potent PPARdelta transactivation activity and highest PPARdelta selectivity. The (S)-enantiomer of a representative compound (TIPP-204) exhibited extremely potent PPARdelta transactivation activity, comparable to that of the known PPARdelta-selective agonist GW-501516. To understand why TIPP-204 shows high selectivity for hPPARdelta among hPPAR subtypes, and why TIPP-401, a structurally related compound, is a hPPARalpha/delta dual agonist, computational docking of TIPP-401 to the ligand binding domains of hPPARalpha and hPPARdelta and X-ray structure analysis of TIPP-204-hPPARdelta ligand binding domain were carried out. The results allowed identification of certain amino acids as putative determinants of the hPPARdelta selectivity of TIPP-204. To confirm the significance of these amino acids, GAL4-fusion proteins of mutated hPPARdeltas and hPPARalphas were prepared, and the transactivation activity of TIPP-204 toward the mutants was evaluated. The amino acid(s) that predominantly influence the potency and selectivity of TIPP-204 are different from that of the well-known PPARdelta-selective agonist GW-501516, which belongs to a different chemical class. The significance of these amino acids was confirmed by the examination of the complex structure between TIPP-204 and hPPARdelta. The results revealed several interactions relevant to the hPPARdelta-selectivity of the two ligands and will be useful for logical hPPARdelta ligand design. PMID:19483413

Kasuga, Jun-Ichi; Oyama, Takuji; Nakagome, Izumi; Aoyama, Atsushi; Sako, Kumiko; Makishima, Makoto; Hirono, Shuichi; Morikawa, Kosuke; Hashimoto, Yuichi; Miyachi, Hiroyuki

2009-06-01

152

Differential modulation of agonist and antagonist structure activity relations for rat TRPV1 by cyclosporin A and other protein phosphatase inhibitors.  

PubMed

The transient receptor potential V1 channel (vanilloid receptor, TRPV1) represents a promising therapeutic target for inflammatory pain and other conditions involving C-fiber sensory afferent neurons. Sensitivity of TRPV1 is known to be subject to modulation by numerous signaling pathways, in particular by phosphorylation, and we wished to determine whether TRPV1 structure activity relations could be differentially affected. We demonstrate here that the structure activity relations of TRPV1, as determined by (45)Ca(2) uptake, were substantially altered by treatment of the cells with cyclosporin A, an inhibitor of protein phosphatase 2B. Whereas the potency of resiniferatoxin for stimulation of (45)Ca(2) was not altered by cyclosporin A treatment, the potencies of some other agonists were increased up to 8-fold. Among the antagonists examined, potencies were reduced to a lesser extent, ranging from 1- to 2.5-fold. Finally, the efficacy of partial agonists was increased. In contrast to cyclosporin A, okadaic acid, an inhibitor of protein phosphatases 1 and 2A, had little effect on agonist potencies, and calyculin A, an inhibitor of protein phosphatases 1 and 2A but with somewhat different selectivity from that of okadaic acid, caused changes in structure activity relations distinct from those induced by cyclosporin A. Because phosphatase activity differentially modulates the structure activity relations of TRPV1 agonists and antagonists, our findings predict that it may be possible to design agonists and antagonists selective for TRPV1 in a specific regulatory environment. A further implication is that it may be desirable to tailor screening approaches for drug discovery to reflect the desired regulatory state of the targeted TRPV1. PMID:18259730

Pearce, Larry V; Toth, Attila; Ryu, HyungChul; Kang, Dong Wook; Choi, Hyun-Kyung; Jin, Mi-Kyoung; Lee, Jeewoo; Blumberg, Peter M

2008-04-01

153

Peroxisome proliferator-activated receptor (PPAR) ? and PPAR? agonists modulate mitochondrial fusion-fission dynamics: relevance to reactive oxygen species (ROS)-related neurodegenerative disorders?  

PubMed

Recent studies showed that the activation of the retinoid X receptor, which dimerizes with peroxisome proliferator-activated receptors (PPARs), leads to an enhanced clearance of A? from the brain of transgenic mice model of Alzheimer's disease (AD), because an increased expression of apolipoprotein E and it main transporters. However, the effects observed must involve additional underlying mechanisms that have not been yet explored. Several studies conducted in our laboratory suggest that part of the effects observed for the PPARs agonist might involves mitochondrial function and, particularly, mitochondrial dynamics. In the present study we assessed the effects of oxidative stress challenge on mitochondrial morphology and mitochondrial dynamics-related proteins in hippocampal neurons. Using immunofluorescence, we evaluated the PPAR? co-activator 1? (PGC-1?), dynamin related protein 1 (DRP1), mitochondrial fission protein 1 (FIS1), and mitochondrial length, in order to determine if PPARs agonist pre-treatment is able to protect mitochondrial population from hippocampal neurons through modulation of the mitochondrial fusion-fission events. Our results suggest that both a PPAR? agonist (ciglitazone) and a PPAR? agonist (WY 14.643) are able to protect neurons by modulating mitochondrial fusion and fission, leading to a better response of neurons to oxidative stress, suggesting that a PPAR based therapy could acts simultaneously in different cellular components. Additionally, our results suggest that PGC-1? and mitochondrial dynamics should be further studied in future therapy research oriented to ameliorate neurodegenerative disorders, such as AD. PMID:23675519

Zolezzi, Juan M; Silva-Alvarez, Carmen; Ordenes, Daniela; Godoy, Juan A; Carvajal, Francisco J; Santos, Manuel J; Inestrosa, Nibaldo C

2013-01-01

154

Peroxisome Proliferator-Activated Receptor (PPAR) ? and PPAR? Agonists Modulate Mitochondrial Fusion-Fission Dynamics: Relevance to Reactive Oxygen Species (ROS)-Related Neurodegenerative Disorders?  

PubMed Central

Recent studies showed that the activation of the retinoid X receptor, which dimerizes with peroxisome proliferator-activated receptors (PPARs), leads to an enhanced clearance of A? from the brain of transgenic mice model of Alzheimer’s disease (AD), because an increased expression of apolipoprotein E and it main transporters. However, the effects observed must involve additional underlying mechanisms that have not been yet explored. Several studies conducted in our laboratory suggest that part of the effects observed for the PPARs agonist might involves mitochondrial function and, particularly, mitochondrial dynamics. In the present study we assessed the effects of oxidative stress challenge on mitochondrial morphology and mitochondrial dynamics-related proteins in hippocampal neurons. Using immunofluorescence, we evaluated the PPAR? co-activator 1? (PGC-1?), dynamin related protein 1 (DRP1), mitochondrial fission protein 1 (FIS1), and mitochondrial length, in order to determine if PPARs agonist pre-treatment is able to protect mitochondrial population from hippocampal neurons through modulation of the mitochondrial fusion-fission events. Our results suggest that both a PPAR? agonist (ciglitazone) and a PPAR? agonist (WY 14.643) are able to protect neurons by modulating mitochondrial fusion and fission, leading to a better response of neurons to oxidative stress, suggesting that a PPAR based therapy could acts simultaneously in different cellular components. Additionally, our results suggest that PGC-1? and mitochondrial dynamics should be further studied in future therapy research oriented to ameliorate neurodegenerative disorders, such as AD. PMID:23675519

Zolezzi, Juan M.; Silva-Alvarez, Carmen; Ordenes, Daniela; Godoy, Juan A.; Carvajal, Francisco J.; Santos, Manuel J.; Inestrosa, Nibaldo C.

2013-01-01

155

Expression of peroxisome proliferator-activated receptor (PPAR)? in gastric cancer and inhibitory effects of PPAR? agonists  

PubMed Central

Peroxisome proliferator-activated receptor (PPAR) ? is expressed in human colon cancer, prostate cancer and breast cancer cells, and PPAR? activation induces growth inhibition in these cells. PPAR? expression in human gastric cancer cells, however, has not been fully investigated. We report the PPAR? expression in human gastric cancer, and the effect of PPAR? ligands on proliferation of gastric carcinoma cell lines. Immunohistochemistry was used to demonstrate the presence of PPAR? protein in surgically resected specimens from well differentiated, moderately differentiated and poorly differentiated adenocarcinoma. We used reverse transcription-polymerase chain reaction and Northern and Western blot analyses to demonstrate PPAR? expression in four human gastric cancer cell lines. PPAR? agonists (troglitazone and 15-deoxy-?12,14-prostaglandin J2) showed dose-dependent inhibitory effects on the proliferation of the gastric cancer cells, and their effect was augmented by the simultaneous addition of 9-cis retinoic acid, a ligand of RXR?. Flow cytometry demonstrated G1 cell cycle arrest and a significant increase of annexin V-positive cells after treatment with troglitazone. These results suggest that induction of apoptosis together with G1 cell cycle arrest may be one of the mechanisms of the antiproliferative effect of PPAR? activation in human gastric cancer cells. © 2000 Cancer ResearchCampaign PMID:11044367

Sato, H; Ishihara, S; Kawashima, K; Moriyama, N; Suetsugu, H; Kazumori, H; Okuyama, T; Rumi, M A K; Fukuda, R; Nagasue, N; Kinoshita, Y

2000-01-01

156

Antitussive activity of sigma-1 receptor agonists in the guinea-pig  

Microsoft Academic Search

1 Current antitussive medications have limited efficacy and often contain the opiate-like agent dextromethorphan (DEX). The mechanism whereby DEX inhibits cough is ill defined. DEX displays affinity at both NMDA and sigma receptors, suggesting that the antitussive activity may involve central or peripheral activity at either of these receptors. This study examined and compared the antitussive activity of DEX and

Claire Brown; Malika Fezoui; William M. Selig; Carl E. Schwartz; James L. Ellis

2004-01-01

157

The relative contribution of affinity and efficacy to agonist activity: organ selectivity of noradrenaline and oxymetazoline with reference to the classification of drug receptors.  

PubMed Central

Oxymetazoline demonstrated a pronounced organ selectivity, when compared to noradrenaline, by being a potent full agonist in rat anococcygeus muscle and a partial agonist in rat vas deferens. Responses of rat anococcygeus muscles to oxymetazoline were relatively more sensitive to antagonism by phenoxybenzamine (Pbz) an alkylating alpha-adrenoceptor antagonist. Therefore, although oxymetazoline was more potent than noradrenaline in this tissue, after Pbz (0.3 microM for 10 min), the responses to oxymetazoline were completely inhibited while those to noradrenaline were only partially inhibited. Schild analysis with phentolamine, corynanthine, prazosin and yohimbine indicated no alpha-adrenoceptor heterogeneity within the rat anococcygeus muscle or between this tissue and rat vas deferens. Measurement of agonist Kd values and Schild analysis of oxymetazoline antagonism of responses to noradrenaline (after alkylation) confirmed the homogeneity of alpha-adrenoceptors with respect to these two agonists. The above profiles of activity would be predicted if oxymetazoline had a higher affinity but lower efficacy than noradrenaline. Experimentally this was confirmed when it was found that oxymetazoline had 5 times the affinity but 0.2 to 0.3 times the efficacy of noradrenaline. These results serve as a caveat to the use of selective receptor desensitization and/or selective receptor alkylation (or protection from alkylation) as means of differentiating drug receptors. Theoretical modelling and these experimental results indicate that high affinity/low efficacy agonists are much more sensitive to receptor coupling. The implications for therapeutic selectivity could be important in that high affinity/low efficacy agonists theoretically have a much greater potential for organ selectivity. PMID:6322891

Kenakin, T. P.

1984-01-01

158

Regulation of peroxisome proliferator-activated receptor ?/? expression and activity levels by toll-like receptor agonists and MAP kinase inhibitors in rat astrocytes.  

PubMed

Peroxisome proliferator-activated receptor ?/? (PPAR?/?) is a potential regulator of neuroinflammation. Toll-like receptors (TLR) are innate immunity-related receptors of inflammatory stimuli. In the present report, we evaluate the molecular mechanisms of regulation of mRNA, protein, and transcriptional activity levels of PPAR?/? by agonists of TLR4, TLR1/2, and TLR5, using lipopolysaccharide (LPS), peptidoglycan, and flagellin, respectively. We found that these stimuli increase the PPAR?/? levels in astrocytes. Expression and activity of PPAR?/? are separately regulated by inhibitors of p38, MEK1/2, extracellular signal-regulated kinases 1/2, and c-Jun N-terminal Kinase mitogen-activated protein kinases. The LPS-induced kinetics of PPAR?/? expression is similar to that of the proinflammatory gene cyclooxygenase 2. Moreover, for both genes the expression depends on nuclear factor kappa-light-chain-enhancer of activated B cells and p38, and is induced after inhibition of protein synthesis. The up-regulation of the expression after inhibition of protein synthesis signifies the participation of a labile protein in regulation of PPAR?/? expression. In contrast to cyclooxygenase 2, the cycloheximide-sensitive PPAR?/? expression was not responsive to nuclear factor kappa-light-chain-enhancer of activated B cells inhibition. Measurements of PPAR?/? mRNA stability showed that the PPAR?/? mRNA levels are regulated post-transcriptionally. We found that in LPS-stimulated astrocytes, the half-life of PPAR?/? mRNA was 50 min. Thus, we demonstrate that PPAR?/? expression and activity are regulated in TLR agonist-stimulated astrocytes by mechanisms that are widely used for regulation of proinflammatory genes. Protein expression level of nuclear receptor PPAR?/? is important for functions of this transcription factor. We investigate the regulatory mechanisms of PPAR?/? in rat primary astrocytes stimulated by agonists of toll-like receptors (TLR): TLR4, TLR1/2, and TLR5. Expression, activity, mRNA stability, and superinduction of PPAR?/? were up-regulated after TLR stimulation. These processes are sensitive to MAPKs and NF-kB inhibitors. Superinduction is up-regulation of mRNA expression after inhibition of protein synthesis. PMID:24806616

Chistyakov, Dmitry V; Aleshin, Stepan; Sergeeva, Marina G; Reiser, Georg

2014-08-01

159

Protease-Activated Receptor – 2 (PAR-2) is a weak enhancer of mucin secretion by human bronchial epithelial cells in vitro  

PubMed Central

PAR-2, a member of a family of G-protein-coupled receptors, can be activated by serine proteases via proteolytic cleavage. PAR-2 expression is known to be upregulated in respiratory epithelium subsequent to inflammation in asthma and chronic obstructive pulmonary disease (COPD). Since these diseases also are characterized by excessive mucus production and secretion, we investigated whether PAR-2 could be linked to mucin hypersecretion by airway epithelium. Normal human bronchial epithelial (NHBE) cells in primary culture or the human bronchial epithelial cell lines, NCI-H292 and HBE-1, were used. NHBE, NCI-H292, and HBE-1 cells expressed prominent levels of PAR-2 protein. Short term (30 min) exposure of cells to the synthetic PAR-2 agonist peptide (SLIGKV-NH2) elicited a small but statistically significant increase in mucin secretion at high concentrations (100µM and 1000µM), compared to a control peptide with reversed amino acid sequence (VKGILS-NH2). Neither human lung tryptase nor bovine pancreatic trypsin, both PAR-2 agonists, affected NHBE cell mucin secretion when added over a range of concentrations. Knockdown of PAR-2 expression by siRNA blocked the stimulatory effect of the AP. The results suggest that, since PAR-2 activation only weakly increases mucin secretion by human airway epithelial cells in vitro, PAR-2 probably is not a significant contributor to mucin hypersecretion in inflamed airways. PMID:18077203

Lin, Ko-Wei; Park, Joungjoa; Crews, Anne L.; Li, Yuehua; Adler, Kenneth B.

2008-01-01

160

Stimulation of the p38 Mitogen-activated Protein Kinase Pathway in Neonatal Rat Ventricular Myocytes by the G Protein-coupled Receptor Agonists, Endothelin1 and Phenylephrine: A Role in Cardiac Myocyte Hypertrophy?  

Microsoft Academic Search

We examined the activation of the p38 mito- gen-activated protein kinase (p38-MAPK) pathway by the G protein-coupled receptor agonists, endothelin-1 and phenylephrine in primary cultures of cardiac myo- cytes from neonatal rat hearts. Both agonists increased the phosphorylation (activation) of p38-MAPK by z 12-fold. A p38-MAPK substrate, MAPK-activated protein kinase 2 (MAPKAPK2), was activated approxi- mately fourfold and 10 m

Angela Clerk; Ashour Michael; Peter H. Sugden

1998-01-01

161

Agonist-induced conformational changes in bovine rhodopsin: insight into activation of G-protein-coupled receptors.  

PubMed

Activation of G-protein-coupled receptors (GPCRs) is initiated by conformational changes in the transmembrane (TM) helices and the intra- and extracellular loops induced by ligand binding. Understanding the conformational changes in GPCRs leading to activation is imperative in deciphering the role of these receptors in the pathology of diseases. Since the crystal structures of activated GPCRs are not yet available, computational methods and biophysical techniques have been used to predict the structures of GPCR active states. We have recently applied the computational method LITiCon to understand the ligand-induced conformational changes in beta(2)-adrenergic receptor by ligands of varied efficacies. Here we report a study of the conformational changes associated with the activation of bovine rhodopsin for which the crystal structure of the inactive state is known. Starting from the inactive (dark) state, we have predicted the TM conformational changes that are induced by the isomerization of 11-cis retinal to all-trans retinal leading to the fully activated state, metarhodopsin II. The predicted active state of rhodopsin satisfies all of the 30 known experimental distance constraints. The predicted model also correlates well with the experimentally observed conformational switches in rhodopsin and other class A GPCRs, namely, the breaking of the ionic lock between R135(3.50) at the intracellular end of TM3 (part of the DRY motif) and E247(6.30) on TM6, and the rotamer toggle switch on W265(6.48) on TM6. We observe that the toggling of the W265(6.48) rotamer modulates the bend angle of TM6 around the conserved proline. The rotamer toggling is facilitated by the formation of a water wire connecting S298(7.45), W265(6.48) and H211(5.46). As a result, the intracellular ends of TMs 5 and 6 move outward from the protein core, causing large conformational changes at the cytoplasmic interface. The predicted outward movements of TM5 and TM6 are in agreement with the recently published crystal structure of opsin, which is proposed to be close to the active-state structure. In the predicted active state, several residues in the intracellular loops, such as R69, V139(3.54), T229, Q237, Q239, S240, T243 and V250(6.33), become more water exposed compared to the inactive state. These residues may be involved in mediating the conformational signal from the receptor to the G protein. From mutagenesis studies, some of these residues, such as V139(3.54), T229 and V250(6.33), are already implicated in G-protein activation. The predicted active state also leads to the formation of new stabilizing interhelical hydrogen-bond contacts, such as those between W265(6.48) and H211(5.46) and E122(3.37) and C167(4.56). These hydrogen-bond contacts serve as potential conformational switches offering new opportunities for future experimental investigations. The calculated retinal binding energy surface shows that binding of an agonist makes the receptor dynamic and flexible and accessible to many conformations, while binding of an inverse agonist traps the receptor in the inactive state and makes the other conformations inaccessible. PMID:18638482

Bhattacharya, Supriyo; Hall, Spencer E; Vaidehi, Nagarajan

2008-10-01

162

Delta-9-tetrahydrocannabinol differentially suppresses emesis versus enhanced locomotor activity produced by chemically diverse dopamine D2/D3 receptor agonists in the least shrew (Cryptotis parva).  

PubMed

The principal psychoactive component of marijuana, delta-9-tetrahydrocannabinol (Delta9-THC), suppresses nausea and vomiting in cancer patients caused by chemotherapeutics such as cisplatin. Cisplatin induces vomiting via a number of emetic stimuli, including dopamine. Currently, there is controversy as to whether Delta9-THC can prevent emesis produced by dopaminergic agonists such as apomorphine. The present investigation utilizes the least shrew to evaluate the antiemetic potential and the cannabinoid receptor by which Delta9-THC may prevent emesis produced by four dopamine receptor agonists with differing selectivity for D2 and D3 receptors, i.e., a nonselective dopamine receptor agonist (apomorphine), a D2-preferring receptor agonist (quinpirole), and two D3-preferring receptor agonists (quinelorane and 7-OH DPAT). In addition, relative to its antiemetic doses, the motor suppressive doses of Delta9-THC in dopamine D2/D3-receptor-agonist-treated shrews were also evaluated. Thus, different groups of shrews were injected with either vehicle (V) or varying doses of Delta9-THC [0.5, 1, 2.5, 5, or 10 mg/kg, intraperitoneal (i.p.)] 10 min prior to administration of a 2 mg/kg dose of one of the four cited D2/D3 agonists. Immediately after the last injection, the frequency of vomiting for each shrew was recorded for the next 30 min. To investigate which cannabinoid receptor is involved in the antiemetic action of Delta9-THC, various doses of the CB1 receptor antagonist SR 141716A [0, 5, 10, and 20 mg/kg, subcutaneous (s.c.)] were administered to shrews 10 min prior to an injection of a fully effective antiemetic dose of Delta9-THC (5 mg/kg, i.p.). Ten minutes later, each treated shrew was administered with a 2 mg/kg dose of apomorphine. The emesis frequency was recorded for the next 30 min. For locomotor studies, different groups of shrews received either vehicle or various doses of Delta9-THC (0, 5, 10, 20, or 30 mg/kg) 10 min prior to an injection of vehicle or a 2 mg/kg dose of one of the four D2/D3 receptor agonists. The triad of motor behaviors (spontaneous locomotor activity, total duration of movement, and rearing frequency) were recorded for the next 30 min by a computerized video tracking system. Delta9-THC dose-dependently attenuated the frequency of emesis as well as fully protecting shrews from vomiting produced by each one of the four cited dopamine D2/D3 receptor agonists with ID50s ranging from 1 to 4 mg/kg. SR 141716A reversed the antiemetic activity of Delta9-THC against apomorphine-induced emesis. Delta9-THC also differentially suppressed the triad of motor activities in dopamine D2/D3-receptor-agonist-treated shrews with ID50s ranging from 7 to 21 mg/kg. The results suggest that Delta9-THC prevents emesis via cannabinoid CB1 receptors in a potent and dose-dependent manner in D2/D3-receptor-agonist-treated shrews at doses well below those which cause significant motor depression. PMID:15652378

Darmani, Nissar A; Crim, Jennifer L

2005-01-01

163

Extending the structure-activity relationship of anthranilic Acid derivatives as farnesoid x receptor modulators: development of a highly potent partial farnesoid x receptor agonist.  

PubMed

The ligand activated transcription factor nuclear farnesoid X receptor (FXR) is involved as a regulator in many metabolic pathways including bile acid and glucose homeostasis. Therefore, pharmacological activation of FXR seems a valuable therapeutic approach for several conditions including metabolic diseases linked to insulin resistance, liver disorders such as primary biliary cirrhosis or nonalcoholic steatohepatitis, and certain forms of cancer. The available FXR agonists, however, activate the receptor to the full extent which might be disadvantageous over a longer time period. Hence, partial FXR activators are required for long-term treatment of metabolic disorders. We here report the SAR of anthranilic acid derivatives as FXR modulators and development, synthesis, and characterization of compound 51, which is a highly potent partial FXR agonist in a reporter gene assay with an EC50 value of 8 ± 3 nM and on mRNA level in liver cells. PMID:25255039

Merk, Daniel; Lamers, Christina; Ahmad, Khalil; Carrasco Gomez, Roberto; Schneider, Gisbert; Steinhilber, Dieter; Schubert-Zsilavecz, Manfred

2014-10-01

164

Activation of nociceptin/orphanin FQ peptide receptors disrupts visual but not auditory sensorimotor gating in BALB/cByJ mice: comparison to dopamine receptor agonists.  

PubMed

Nociceptin/orphanin FQ (N/OFQ) peptide and its receptor (NOP receptor) have been implicated in a host of brain functions and diseases, but the contribution of this neuropeptide system to behavioral processes of relevance to psychosis has not been investigated. We examined the effect of the NOP receptor antagonists, Compound 24 and J-113397, and the synthetic agonist, Ro64-6198, on time function (2-2000?ms prepulse-pulse intervals) of acoustic (80?dB/10?ms prepulse) and visual (1000?Lux/20?ms prepulse) prepulse inhibition of startle reflex (PPI), a preattentive sensory filtering mechanism that is central to perceptual and mental integration. The effects of the dopamine D1-like receptor agonist, SKF-81297, the D2-like receptor agonist, quinelorane, and the mixed D1/D2 agonist, apomorphine, were studied for comparison. When acoustic stimulus was used as prepulse, BALB/cByJ mice displayed a monotonic time function of PPI, and consistent with previous studies, apomorphine and SKF-81279 induced PPI impairment, whereas quinelorane had no effect. None of the NOP receptor ligands was effective on acoustic PPI. When flash light was used as prepulse, BALB/cByJ mice displayed a bell-shaped time function of PPI and all dopamine agonists were active. Ro64-6198 was also effective in reducing visual PPI. NOP receptor antagonists showed no activity but blocked disruptive effect of Ro64-6198. Finally, coadministration of the typical antipsychotic, haloperidol, attenuated PPI impairment induced by Ro64-6198, revealing involvement of a dopaminergic component. These findings show that pharmacological stimulation of NOP or dopamine D2-like receptors is more potent in disrupting visual than acoustic PPI in mice, whereas D1-like receptor activation disrupts both. They further suggest that dysfunction of N/OFQ transmission may be implicated in the pathogenesis of psychotic manifestations. PMID:21881568

Ces, Aurelia; Reiss, David; Walter, Ondine; Wichmann, Jürgen; Prinssen, Eric P; Kieffer, Brigitte L; Ouagazzal, Abdel-Mouttalib

2012-01-01

165

?-Adrenergic agonists increase phosphorylation of elongation factor 2 in cardiomyocytes without eliciting calcium-independent eEF2 kinase activity  

Microsoft Academic Search

The ?-adrenergic agonist isoproterenol increased the phosphorylation of elongation factor eEF2 in ventricular cardiomyocytes from adult rats (ARVC). Phosphorylation of eEF2 inhibits its activity, and protein synthesis was inhibited in ARVC concomitantly with increased eEF2 phosphorylation. eEF2 kinase activity in ARVC extracts was completely dependent upon Ca2+\\/calmodulin. In contrast to other cell types, however, treatments designed to raise intracellular cAMP

Laura E McLeod; Lijun Wang; Christopher G Proud

2001-01-01

166

Truncation of the peptide sequence in bifunctional ligands with mu and delta opioid receptor agonist and neurokinin 1 receptor antagonist activities  

PubMed Central

The optimization and truncation of our lead peptide-derived ligand TY005 possessing eight amino-acid residues was performed. Among the synthesized derivatives, NP30 (Tyr1-DAla2-Gly3-Phe4-Gly5-Trp6-O-[3?,5?-Bzl(CF3)2]) showed balanced and potent opioid agonist as well as substance P antagonist activities in isolated tissue-based assays, together with significant antinociceptive and antiallodynic activities in vivo. PMID:23899615

Nair, Padma; Yamamoto, Takashi; Largent-Milnes, Tally M.; Cowell, Scott; Kulkarni, Vinod; Moye, Sharif; Navratilova, Edita; Davis, Peg; Ma, Shou-Wu; Vanderah, Todd W.; Lai, Josephine; Porreca, Frank; Hruby, Victor J.

2013-01-01

167

Synthesis of a potent agonist of substance P by modifying the methionyl and glutaminyl residues of the C-terminal hexapeptide of substance P. Structure-activity relationships.  

PubMed

Analogues of [Orn6]-SP6-11 have been synthesized in which the Met11 residue is replaced by glutamate gamma-alkylesters. These analogues were tested in three in vitro preparations representative of NK-1, NK-2, and NK-3 receptor types. Substitution of the SCH3 group of the Met11 side chain by a COOR (R = methyl, ethyl, n-propyl, n-butyl, cyclohexyl) group results in analogues which are full agonists in NK-1 and NK-2 preparations but show little agonist activity in the NK-3 preparation. When the SCH3 group is replaced by a t-butyl ester group and the resulting analogue is a full agonist in all the above preparations and more active than the parent hexapeptide and SP-OCH3 at NK-1 receptors. It is concluded that for activity at NK-1 receptors methionine can be replaced by gamma-t-butyl glutamate without loss of activity, whilst at NK-2 and NK-3 receptors the above substitution increases the activity of [Orn6]-SP6-11. Other gamma-alkyl esters of the glutamic acid reduce its biological activity. PMID:1724664

Karagiannis, K; Manolopoulou, A; Stavropoulos, G; Poulos, C; Jordan, C C; Hagan, R M

1991-10-01

168

CMHX008, a Novel Peroxisome Proliferator-Activated Receptor ? Partial Agonist, Enhances Insulin Sensitivity In Vitro and In Vivo  

PubMed Central

The peroxisome proliferator-activated receptor ? (PPAR?) plays an important role in adipocyte differentiation and insulin sensitivity. Its ligand rosiglitazone has anti-diabetic effect but is frequently accompanied with some severe unwanted effects. The aim of the current study was to compare the anti-diabetic effect of CMHX008, a novel thiazolidinedione-derivative, with rosiglitazone. A luciferase assay was used to evaluate in vitro PPAR? activation. 3T3-L1 cells were used to examine adipocyte differentiation. High fat diet (HFD) mice were used to examine in vivo insulin sensitivity. The mRNA levels were evaluated by real-time RT-PCR. Serum biochemical and hormonal variables were assessed using a clinical chemistry analyser. CMHX008 displayed a moderate PPAR? agonist activity, and promoted 3T3-L1 preadipocyte differentiation with lower activity than rosiglitazone. CMHX008 regulated the expression of PPAR? target genes in a different manner from rosiglitazone. CMHX008 increased the expression and secretion of adiponectin with the similar efficacy as rosiglitazone, but only 25% as potent as rosiglitazone for the induction of adipocyte fatty acid binding protein. Treatment of CMHX008 and rosiglitazone protected mice from high fat diet (HFD)-induced glucose intolerance, hyperinsulinemia and inflammation. CMHX008 reduced the mRNA expression of M1 macrophage markers, and significantly increased the expressions of M2 markers. In conclusion, CMHX008 shared the comparable insulin-sensitizing effects as rosiglitazone with lower adipogenic capacity and might potentially be developed into an effective agent for the treatment of diabetes and metabolic disorders. PMID:25004107

Song, Ying; Liu, Zhiguo; Li, Jibin; Gao, Rufei; Zhang, Yuyao; Mei, Hu; Guo, Tingwang; Xiao, Ling; Wang, Bochu; Wu, Chaodong; Xiao, Xiaoqiu

2014-01-01

169

Molecular determinants for nuclear receptors selectivity: chemometric analysis, dockings and site-directed mutagenesis of dual peroxisome proliferator-activated receptors ?/? agonists.  

PubMed

A series of previously synthesized chiral derivatives of clofibric and phenylacetic acids, acting as dual agonists towards the peroxisome proliferator-activated receptors (PPARs) ? and ?, was taken into account, and the efficacy of these compounds was analyzed by means of 2D-, 3D-QSAR and docking studies with the goal to gain deeper insights into the three-dimensional determinants governing ligands selectivity for PPARs. By multiregressional analysis a correlation between the lipophilicity and PPAR? activity was found, whereas for PPAR? the correlation was achieved once efficacy was related to the presence of polar groups on agonists scaffold. Docking of these compounds further corroborated this hypothesis, and then provided a valid support for subsequent chemometric analysis and pharmacophore models development for both receptors subtypes. Computational results suggested site directed mutagenesis experiments which confirmed the importance of amino acid residues in PPAR activity, allowing the identification of critical hotspots most likely taking over PPARs selectivity. PMID:23502212

Carrieri, Antonio; Giudici, Marco; Parente, Mariagiovanna; De Rosas, Mario; Piemontese, Luca; Fracchiolla, Giuseppe; Laghezza, Antonio; Tortorella, Paolo; Carbonara, Giuseppe; Lavecchia, Antonio; Gilardi, Federica; Crestani, Maurizio; Loiodice, Fulvio

2013-05-01

170

Intradermal delivery of TLR agonists in a human explant skin model: preferential activation of migratory dendritic cells by polyribosinic-polyribocytidylic acid and peptidoglycans.  

PubMed

TLR agonists are attractive candidate adjuvants for therapeutic cancer vaccines as they can induce a balanced humoral and T cell-mediated immune response. With a dense network of dendritic cells (DCs) and draining lymphatics, the skin provides an ideal portal for vaccine delivery. Beside direct DC activation, TLR agonists may also induce DC activation through triggering the release of inflammatory mediators by accessory cells in the skin microenvironment. Therefore, a human skin explant model was used to explore the in vivo potential of intradermally delivered TLR agonists to stimulate Langerhans cells and dermal DCs in their natural complex tissue environment. The skin-emigrated DCs were phenotyped and analyzed for T cell stimulatory capacity. We report that, of six tested TLR-agonists, the TLR2 and -3 agonists peptidoglycan (PGN) and polyribosinic-polyribocytidylic acid (Poly I:C) were uniquely able to enhance the T cell-priming ability of skin-emigrated DCs, which, in the case of PGN, was accompanied by Th1 polarization. The enhanced priming capacity of Poly I:C-stimulated DCs was associated with a strong upregulation of appropriate costimulatory molecules, including CD70, whereas that of PGN-stimulated DCs was associated with the release of a broad array of proinflammatory cytokines. Transcriptional profiling further supported the notion that the PGN- and Poly I:C-induced effects were mediated through binding to TLR2/nucleotide-binding oligomerization domain 2 and TLR3/MDA5, respectively. These data warrant further exploration of PGN and Poly I:C, alone or in combination, as DC-targeted adjuvants for intradermal cancer vaccines. PMID:23467931

Oosterhoff, Dinja; Heusinkveld, Moniek; Lougheed, Sinéad M; Kosten, Ilona; Lindstedt, Malin; Bruijns, Sven C M; van Es, Thomas; van Kooyk, Yvette; van der Burg, Sjoerd H; de Gruijl, Tanja D

2013-04-01

171

Conformational toggle switches implicated in basal constitutive and agonist-induced activated states of 5-hydroxytryptamine-4 receptors.  

PubMed

The extended classic ternary complex model predicts that a G protein-coupled receptor (GPCR) exists in only two interconvertible states: an inactive R, and an active R(*). However, different structural active R(*) complexes may exist in addition to a silent inactive R ground state (Rg). Here we demonstrate, in a cellular context, that several R(*) states of 5-hydroxytryptamine-4 (5-HT(4)) receptors involve different side-chain conformational toggle switches. Using site-directed mutagenesis and molecular modeling approaches, we show that the basal constitutive receptor (R(*)basal) results from stabilization of an obligatory double toggle switch (Thr3.36 from inactive g- to active g+ and Trp6.48 from inactive g+ to active t). Mutation of either threonine or tryptophan to alanine resulted in a lowering of the activity of the R(*)basal similar to the Rg. The T3.36A mutation shows that the Thr3.36 toggle switch plays a minor role in the stabilization of R(*) induced by 5-HT (R(*)-5-HT) and BIMU8 (R(*)-BIMU8) and is fully required in the stabilization of R(*) induced by (S)-zacopride, cisapride, and 1-(4-amino-5-chloro-2-methoxyphenyl)-3-(1-butyl-4-piperidinyl)-1-propanone (RS 67333) (R(*)-benzamides). Thus, benzamides stabilize R(*)-benzamides by forming a specific hydrogen bond with Thr3.36 in the active g+ conformation. Conversely, R(*)-BIMU8 was probably the result of a direct conformational transition of Trp6.48 from inactive g+ to active t by hydrogen bonding of this residue to a carboxyl group of BIMU8. We were surprised that the Trp6.48 toggle switch was not necessary for receptor activation by the natural agonist 5-HT. R(*)-5-HT is probably attained through other routes of activation. Thus, different conformational arrangements occur during stabilization of R(*)basal, R(*)-5-HT, R(*)-benzamides, and R(*)-BIMU8. PMID:19168624

Pellissier, Lucie P; Sallander, Jessica; Campillo, Mercedes; Gaven, Florence; Queffeulou, Emilie; Pillot, Marion; Dumuis, Aline; Claeysen, Sylvie; Bockaert, Joël; Pardo, Leonardo

2009-04-01

172

Actions of Peroxisome Proliferator–Activated Receptors–? Agonists Explaining a Possible Blood Pressure–Lowering Effect  

Microsoft Academic Search

The metabolic syndrome is a cluster of disturbances such as type 2 diabetes mellitus, hypertension, central obesity, dyslipidemia, and others for which insulin resistance and compensatory hyperinsulinemia have been proposed to be the underlying disorders. Several possible mechanisms linking insulin resistance and compensatory hyperinsulinemia with hypertension have been described, such as renal sodium reabsorption enhancement, sympathetic nervous system activation, and

Panteleimon A. Sarafidis; Anastasios N. Lasaridis

2006-01-01

173

Protease-activated receptor 2 agonist increases cell proliferation and invasion of human pancreatic cancer cells  

PubMed Central

The aim of this study was to determine the expression of protease-activated receptor 2 (PAR-2) in the human pancreatic cancer cell line SW1990, and to evaluate its effect on cell proliferation and invasion. The expression of PAR-2 protein and mRNA in SW1990 cells was determined by immunocytochemistry and reverse transcription polymerase chain reaction (PCR), respectively. MTT and cell invasion and migration assays, as well as semi-quantitative PCR and zymography analysis, were additionally performed. PAR-2 mRNA was significantly upregulated in the cells treated with trypsin or the PAR-2 activating peptide Ser-Leu-Ile-Gly-Lys-Val (SLIGKV) (P<0.01), but not in the Val-Lys-Gly-Ile-Leu-Ser group (P>0.05). Trypsin and SLIGKV significantly promoted SW1990 cell proliferation in a dose- and time-dependent manner (P<0.05). Compared with the control group, trypsin and SLIGKV significantly increased the mRNA expression (P<0.01) and gelatinolytic activity (P<0.01) of matrix metalloproteinase (MMP)-2. In conclusion, PAR-2 is expressed in SW1990 cells. PAR-2 activation may promote the invasion and migration of human pancreatic cancer cells by increasing MMP-2 expression.

XIE, LIQUN; DUAN, ZEXING; LIU, CAIJU; ZHENG, YANMIN; ZHOU, JING

2015-01-01

174

Targeting human CD27 with an agonist antibody stimulates T-cell activation and antitumor immunity  

PubMed Central

CD27 is an important co-stimulatory receptor of T cells that can potentially be exploited for immunotherapy. We developed a human IgG1 antibody that targets human CD27, and demonstrated its immunostimulatory and antineoplastic activity in various preclinical models. Currently, the antibody (1F5, CDX-1127) is being tested in patients affected by advanced malignancies. PMID:24605266

Thomas, Lawrence J; He, Li-Zhen; Marsh, Henry; Keler, Tibor

2014-01-01

175

Phospholipid-esterified Eicosanoids Are Generated in Agonist-activated Human Platelets and Enhance Tissue Factor-dependent Thrombin Generation*  

PubMed Central

Here, a group of specific lipids, comprising phosphatidylethanolamine (PE)- or phosphatidylcholine (PC)-esterified 12S-hydroxyeicosatetraenoic acid (12S-HETE), generated by 12-lipoxygenase was identified and characterized. 12S-HETE-PE/PCs were formed within 5 min of activation by thrombin, ionophore, or collagen. Esterified HETE levels generated in response to thrombin were 5.85 ± 1.42 (PE) or 18.35 ± 4.61 (PC), whereas free was 65.5 ± 17.6 ng/4 × 107 cells (n = 5 separate donors, mean ± S.E.). Their generation was stimulated by triggering protease-activated receptors-1 and -4 and signaling via Ca2+ mobilization secretory phospholipase A2, platelet-activating factor-acetylhydrolase, src tyrosine kinases, and protein kinase C. Stable isotope labeling showed that they form predominantly by esterification that occurs on the same time scale as free acid generation. Unlike free 12S-HETE that is secreted, esterified HETEs remain cell-associated, with HETE-PEs migrating to the outside of the plasma membrane. 12-Lipoxygenase inhibition attenuated externalization of native PE and phosphatidylserine and HETE-PEs. Platelets from a patient with the bleeding disorder, Scott syndrome, did not externalize HETE-PEs, and liposomes supplemented with HETE-PC dose-dependently enhanced tissue factor-dependent thrombin generation in vitro. This suggests a role for these novel lipids in promoting coagulation. Thus, oxidized phospholipids form by receptor/agonist mechanisms, not merely as an undesirable consequence of vascular and inflammatory disease. PMID:20061396

Thomas, Christopher P.; Morgan, Lloyd T.; Maskrey, Benjamin H.; Murphy, Robert C.; Kuhn, Hartmut; Hazen, Stanley L.; Goodall, Alison H.; Hamali, Hassan A.; Collins, Peter W.; O'Donnell, Valerie B.

2010-01-01

176

Activation and desensitization of TRPV1 channels in sensory neurons by the PPAR? agonist palmitoylethanolamide  

PubMed Central

Background and Purpose Palmitoylethanolamide (PEA) is an endogenous fatty acid amide displaying anti-inflammatory and analgesic actions. To investigate the molecular mechanism responsible for these effects, the ability of PEA and of pain-inducing stimuli such as capsaicin (CAP) or bradykinin (BK) to influence intracellular calcium concentrations ([Ca2+]i) in peripheral sensory neurons, has been assessed in the present study. The potential involvement of the transcription factor PPAR? and of TRPV1 channels in PEA-induced effects was also studied. Experimental Approach [Ca2+]i was evaluated by single-cell microfluorimetry in differentiated F11 cells. Activation of TRPV1 channels was assessed by imaging and patch-clamp techniques in CHO cells transiently-transfected with rat TRPV1 cDNA. Key Results In F11 cells, PEA (1–30 ?M) dose-dependently increased [Ca2+]i. The TRPV1 antagonists capsazepine (1 ?M) and SB-366791 (1 ?M), as well as the PPAR? antagonist GW-6471 (10 ?M), inhibited PEA-induced [Ca2+]i increase; blockers of cannabinoid receptors were ineffective. PEA activated TRPV1 channels heterologously expressed in CHO cells; this effect appeared to be mediated at least in part by PPAR?. When compared with CAP, PEA showed similar potency and lower efficacy, and caused stronger TRPV1 currents desensitization. Sub-effective PEA concentrations, closer to those found in vivo, counteracted CAP- and BK-induced [Ca2+]i transients, as well as CAP-induced TRPV1 activation. Conclusions and Implications Activation of PPAR? and TRPV1 channels, rather than of cannabinoid receptors, largely mediate PEA-induced [Ca2+]i transients in sensory neurons. Differential TRPV1 activation and desensitization by CAP and PEA might contribute to their distinct pharmacological profile, possibly translating into potentially relevant clinical differences. PMID:23083124

Ambrosino, Paolo; Soldovieri, Maria Virginia; Russo, Claudio; Taglialatela, Maurizio

2013-01-01

177

RXR agonists inhibit high glucose-induced upregulation of inflammation by suppressing activation of the NADPH oxidase-nuclear factor-?B pathway in human endothelial cells.  

PubMed

An inflammatory response induced by high glucose is a cause of endothelial dysfunction in diabetes and is an important contributing link to atherosclerosis. Diabetes is an independent risk factor of atherosclerosis and activation of retinoid X receptor (RXR) has been shown to exert anti-atherogenic effects. In the present study, we examined the effects of the RXR ligands 9-cis-retinoic acid (9-cis-RA) and SR11237 on high glucose-induced inflammation in human umbilical endothelial vein endothelial cells (HUVECs) and explored the potential mechanism. Our results showed that the inflammation induced by high-glucose in HUVECs was mainly mediated by the activation of nuclear factor-B (NF- ?B). High glucose-induced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were in comparison, significantly decreased by treatment with RXR. The effect of RXR agonists was mainly due to the inhibition of NF-?B activation. Using pharmacological inhibitors and siRNA, we confirmed that nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was an upstream activator of NF-?B. Furthermore, RXR agonists significantly inhibited high glucose-induced activation of NADPH oxidase and significantly decreased the production of reactive oxygen species (ROS). To explore whether the rapid inhibitory effects of RXR agonists were in fact mediated by RXR, we examined the effect of RXR downregulation by RXR siRNA. Our results showed that RXR siRNA largely abrogated the effects of RXR agonists, suggesting the requirement of RXR expression. Therefore, we have shown that RXR is involved in the regulation of NADPH oxidase- NF-?B signal pathway, as the RXR ligands antagonized the inflammatory response in HUVECs induced by high glucose. PMID:24391011

Ning, R B; Zhu, J; Chai, D J; Xu, C S; Xie, H; Lin, X Y; Zeng, J Z; Lin, J X

2013-01-01

178

FXR agonist GW4064 alleviates endotoxin-induced hepatic inflammation by repressing macrophage activation  

PubMed Central

AIM: To examine the effect of farnesoid X receptor (FXR) activation by GW4064 on endotoxin-induced hepatic inflammation in nonalcoholic fatty liver disease (NAFLD) and the underlying mechanism. METHODS: Six-week-old male C57BL/6 mice were fed a normal diet or a high-fat (HF) diet for 8 wk. HF diet-fed mice were intraperitoneally injected with GW4064 (30 mg/kg) or DMSO (vehicle) once daily for a week and then sacrificed after lipopolysaccharide (LPS, 50 ?g/mouse) administration. Hepatic inflammation, levels of the macrophage marker F4/80, and apoptosis were measured at the end of the study. Additionally, the expression of proinflammatory genes involved in NAFLD (interleukin-6, interleukin-1?, interferon-?, MCP-1) were analyzed by real-time PCR in the murine macrophage cell line RAW 264.7 cultured with or without GW4064 (2 ?mol/L) before treatment with LPS. RESULTS: In patients with NAFLD, the expression of FXR was detected by immunohistochemical staining and the relation between FXR expression and NAFLD activity score (NAS) was analyzed. Activation of FXR by GW4064 alleviated hepatic inflammation induced by endotoxin in a murine NAFLD model fed an HF diet as reflected by reduced serum levels of aspartate aminotransferase and alanine aminotransferase. Apoptosis and proinflammatory cytokine levels in liver tissues were also reduced by GW4064, and GW4064 could reduce induction of proinflammatory cytokines by LPS in vitro. FXR levels were reduced in patients with non-alcoholic steatohepatitis compared with healthy controls and were negatively correlated with NAS. CONCLUSION: FXR activation attenuates LPS-induced hepatic inflammation in murine NAFLD by reducing expression of proinflammatory cytokines in macrophages. PMID:25339829

Yao, Jun; Zhou, Chun-Suo; Ma, Xiong; Fu, Bai-Qing; Tao, Li-Sheng; Chen, Miao; Xu, Ya-Ping

2014-01-01

179

Optimization of a Small Tropomyosin-related Kinase B (TrkB) Agonist 7,8-Dihydroxyflavone Active in Mouse Models of Depression  

PubMed Central

Structure-activity relationship study shows that the catechol group in 7,8-dihdyroxyflavone, a selective small TrkB receptor agonist, is critical for the agonistic activity. To improve the poor pharmacokinetic profiles intrinsic to catechol-containing molecules and elevate the agonistic effect of the lead compound, we initiated the lead optimization campaign by synthesizing various bioisosteric derivatives. Here we show that the optimized 2-methyl-8-(4?-(pyrrolidin-1-yl)phenyl)chromeno[7,8-d]imidazol-6(1H)-one derivative possesses the enhanced TrkB stimulatory activity. Chronic oral administration of this compound significantly reduces the immobility in forced swim test and tail suspension test, two classical antidepressant behavioral animal models, which is accompanied by robust TrkB activation in hippocampus of mouse brain. Further, in vitro ADMET studies demonstrate that this compound possesses the improved features compared to the previous lead compound. Hence, this optimized compound may act as a promising lead candidate for in-depth drug development for treating various neurological disorders including depression. PMID:22984948

Liu, Xia; Chan, Chi-Bun; Qi, Qi; Xiao, Ge; Luo, Hongbo R.; He, Xiaolin; Ye, Keqiang

2012-01-01

180

Depletion of the inositol 1,4,5-trisphosphate-sensitive intracellular Ca2+ store in vascular endothelial cells activates the agonist-sensitive Ca(2+)-influx pathway.  

PubMed

Previous studies in non-excitable cells have suggested that depletion of internal Ca2+ stores activates Ca2+ influx from the extracellular space via a mechanism that does not require stimulation of phosphoinositide hydrolysis. To test this hypothesis in vascular endothelial cells, the effect of the Ca(2+)-ATPase/pump inhibitor 2,5-di-t-butylhydroquinone (BHQ) on cytosolic free Ca2+ concentration ([Ca2+]i) was examined. BHQ produced a dose-dependent increase in [Ca2+]i, which remained elevated over basal values for several minutes and was substantially inhibited in the absence of extracellular Ca2+. Application of bradykinin after BHQ demonstrated that the BHQ-sensitive compartment partially overlapped the bradykinin-sensitive store. Similar results were obtained with thapsigargin and cyclopiazonic acid, two other Ca(2+)-ATPase inhibitors. Although BHQ had no effect on phosphoinositide hydrolysis, both 45Ca2+ influx and efflux were stimulated by this agent. These results suggest that depletion of the agonist-sensitive Ca2+ store is sufficient for activation of Ca2+ influx. Several characteristics of the Ca(2+)-influx pathway activated by internal store depletion were compared with those of the agonist-activated pathway. Bradykinin-stimulated Ca2+ influx was increased at alkaline extracellular pH (pHo), and was inhibited by extracellular La3+, by depolarization of the membrane, and by the novel Ca(2+)-influx blocker 1-(beta-[3-(4-methoxyphenyl)propoxy]-4- methoxyphenethyl)-1H-imidazole hydrochloride (SKF 96365). Additionally, bradykinin stimulated influx of both 45Ca2+ and 133Ba2+, consistent with the hypothesis that the agonist-activated influx pathway is permeable to both of these bivalent cations. Likewise, activation of Ca2+ influx by BHQ, thapsigargin and cyclopiazonic acid was blocked by La3+, membrane depolarization and SKF 96365, but was unaffected by nitrendipine or BAY K 8644. Furthermore, Ca2+ influx stimulated by BHQ was increased at alkaline pHo and BHQ stimulated the influx of both 45Ca2+ and 133Ba2+ to the same extent. These results demonstrate that the agonist-activated Ca(2+)-influx pathway and the pathway activated by depletion of the agonist-sensitive internal Ca2+ store are indistinguishable. PMID:1318033

Schilling, W P; Cabello, O A; Rajan, L

1992-06-01

181

FTY720, a new class of immunomodulator, inhibits lymphocyte egress from secondary lymphoid tissues and thymus by agonistic activity at sphingosine 1-phosphate receptors  

Microsoft Academic Search

FTY720 is the first of a new immunomodulator class: sphingosine 1-phosphate (S1P) receptor agonist. In 1994, an immunosuppressive natural product, ISP-I (myriocin), was isolated from the culture broth of Isaria sinclairii, a type of vegetative wasp. The chemical modification of ISP-I yielded a new compound, FTY720, which has more potent immunosuppressive activity and less toxicity than ISP-I does. FTY720 has

Kenji Chiba

2005-01-01

182

Molecular changes associated with the agonist activity of hydroxy-tamoxifen and the hyper-response to estradiol in hydroxy-tamoxifen-resistant breast cancer cell lines  

Microsoft Academic Search

The aim of this study was to explore the pharmacological response to 4-hydroxy-tamoxifen (OH-Tam) and to estradiol (E2) in three cell lines: MVLN, a human breast carcinoma cell line derived from MCF-7, and two MVLN-derived OH-Tam-resistant (OTR) cell lines, called CL6.8 and CL6.32. The OH-Tam response in the OTR cells was associated with the development of both an agonist activity

J A Vendrell; I Bieche; C Desmetz; E Badia; S Tozlu; C Nguyen; J C Nicolas; R Lidereau; P A Cohen

2005-01-01

183

Behavioral effects induced by the dopamine D 3 agonist 7-OH-DPAT in sexually-active and -inactive male rats  

Microsoft Academic Search

The present study investigates the effects induced by the putative DA D3 agonist 7-OH-DPAT (0.1 and 1 mg\\/kg, s.c.) on: (1) the sexual behavior of male rats, categorized on the basis of seven consecutive mating pre-tests as sexually-active (SA) and sexually-inactive (SI); and (2) stretching-yawning, penile erection, sedation and stereotyped behavior of the same animals. The data obtained show that

F. Ferrari; D. Giuliani

1996-01-01

184

The selective mGlu2\\/3 receptor agonist LY354740 attenuates morphine-withdrawal-induced activation of locus coeruleus neurons and behavioral signs of morphine withdrawal  

Microsoft Academic Search

Naltrexone-precipitated morphine withdrawal induces hyperactivity of locus coeruleus (LC) neurons, as well as a plethora of behavioral withdrawal signs. Previous research has demonstrated that an increased release of glutamate and activation of AMPA receptors, particularly in the LC, play an important role in opiate withdrawal. LY354740 is a novel Group II metabotropic glutamate mGlu2\\/3 receptor agonist that decreases the release

Jim Vandergriff; Kurt Rasmussen

1999-01-01

185

Circumventing Seizure Activity in a Series of G Protein Coupled Receptor 119 (GPR119) Agonists.  

PubMed

Agonism of GPR119 is viewed as a potential therapeutic approach for the treatment of type II diabetes and other elements of metabolic syndrome. During progression of a previously disclosed candidate 1 through mice toxicity studies, we observed tonic-clonic convulsions in several mice at high doses. An in vitro hippocampal brain slice assay was used to assess the seizure liability of subsequent compounds, leading to the identification of an aryl sulfone as a replacement for the 3-cyano pyridyl group. Subsequent optimization to improve the overall profile, specifically with regard to hERG activity, led to alkyl sulfone 16. This compound did not cause tonic-clonic convulsions in mice, had a good pharmacokinetic profile, and displayed in vivo efficacy in murine models. Importantly, it was shown to be effective in wild-type (WT) but not GPR119 knockout (KO) animals, consistent with the pharmacology observed being due to agonism of GPR119. PMID:25286150

Scott, James S; Bowker, Suzanne S; Brocklehurst, Katy J; Brown, Hayley S; Clarke, David S; Easter, Alison; Ertan, Anne; Goldberg, Kristin; Hudson, Julian A; Kavanagh, Stefan; Laber, David; Leach, Andrew G; MacFaul, Philip A; Martin, Elizabeth A; McKerrecher, Darren; Schofield, Paul; Svensson, Per H; Teague, Joanne

2014-11-13

186

Actions of Agonists and Antagonists of the ghrelin/GHS-R Pathway on GH Secretion, Appetite, and cFos Activity  

PubMed Central

The stimulatory effects of ghrelin, a 28-AA acylated peptide originally isolated from stomach, on growth hormone (GH) secretion and feeding are exclusively mediated through the growth hormone secretagogue 1a receptor (GHS-R1a), the only ghrelin receptor described so far. Several GHS-R1a agonists and antagonists have been developed to treat metabolic or nutritional disorders but their mechanisms of action in the central nervous system remain poorly understood. In the present study, we compared the activity of BIM-28163, a GHS-R1a antagonist, and of several agonists, including native ghrelin and the potent synthetic agonist, BIM-28131, to modulate food intake, GH secretion, and cFos activity in arcuate nucleus (ArcN), nucleus tractus solitarius (NTS), and area postrema (AP) in wild-type and NPY-GFP mice. BIM-28131 was as effective as ghrelin in stimulating GH secretion, but more active than ghrelin in inducing feeding. It stimulated cFos activity similarly to ghrelin in the NTS and AP but was more powerful in the ArcN, suggesting that the super-agonist activity of BIM-28131 is mostly mediated in the ArcN. BIM-28163 antagonized ghrelin-induced GH secretion but not ghrelin-induced food consumption and cFos activation, rather it stimulated food intake and cFos activity without affecting GH secretion. The level of cFos activation was dependent on the region considered: BIM-28163 was as active as ghrelin in the NTS, but less active in the ArcN and AP. All compounds also induced cFos immunoreactivity in ArcN NPY neurons but BIM-28131 was the most active. In conclusion, these data demonstrate that two peptide analogs of ghrelin, BIM-28163, and BIM-28131, are powerful stimulators of appetite in mice, acting through pathways and key brain regions involved in the control of appetite that are only partially superimposable from those activated by ghrelin. A better understanding of the molecular pathways activated by these compounds could be useful in devising future therapeutic applications, such as for cachexia and anorexia. PMID:23515849

Hassouna, Rim; Labarthe, Alexandra; Zizzari, Philippe; Videau, Catherine; Culler, Michael; Epelbaum, Jacques; Tolle, Virginie

2012-01-01

187

Manipulative management of post-Colles' fracture weakness and diminished active range of motion  

Microsoft Academic Search

Objective: To discuss the management of a patient with wrist weakness and a diminution in active range of motion resulting from Colles' fracture. Clinical Features: A 58-year-old woman complained of persistent loss of grip strength and mobility in her right wrist. These complaints were from Colles' fracture occurring 19 months before initiation of care. Dynamometer and goniometric testing revealed significant

Rod L. Kaufman; Joel Bird

1999-01-01

188

Existence of weak entropic solutions for gas chromatography system with one or two active species  

E-print Network

Existence of weak entropic solutions for gas chromatography system with one or two active species and non convex isotherms. C. Bourdarias , M. Gisclon and S. Junca July 28, 2006 Abstract This paper), the system of conservation laws (6) generalizes the system of chromatography which has been intensively

Gisclon, Marguerite

189

Existence of weak entropy solutions for gas chromatography system with one or two active species  

E-print Network

Existence of weak entropy solutions for gas chromatography system with one or two active species This paper deals with a system of two equations which describes heatless adsorption of a gaseous mixture the system of chromatography which has been intensively studied (see [7, 13] for the Langmuir isotherm

Junca, Stéphane

190

Magnetic Field Variations in the Near Geomagnetic Tail Associated with Weak Substorm Activity  

Microsoft Academic Search

Magnetic field observations obtained with the UCLA Ogo 5 fluxgate magnetometer on an inbound pass, during which the satellite remained close to the magnetic meridian and traveled almost parallel to and approximately 2 Rr above the expected position of the neutral sheet, are used to illustrate the variations in the configuration of the tail field during weak substorm activity. Beyond

C. T. Russell; R. L. McPherron; P. J. Coleman

1971-01-01

191

Benzofuran Derivatives as Potent, Orally Active S1P1 Receptor Agonists: A Preclinical Lead Molecule for MS  

PubMed Central

We have discovered novel benzofuran-based S1P1 agonists with excellent in vitro potency and selectivity. 1-((4-(5-Benzylbenzofuran-2-yl)-3-fluorophenyl)methyl) azetidine-3-carboxylic acid (18) is a potent S1P1 agonist with >1000× selectivity over S1P3. It demonstrated a good in vitro ADME profile and excellent oral bioavailability across species. Dosed orally at 0.3 mg/kg, 18 significantly reduced blood lymphocyte counts 24 h postdose and demonstrated efficacy in a mouse EAE model of relapsing MS. PMID:24900286

2010-01-01

192

Mitemcinal (GM-611), an orally active motilin receptor agonist, improves delayed gastric emptying in a canine model of diabetic gastroparesis.  

PubMed

1. The aim of the present study was to evaluate the effects of mitemcinal (GM-611), an orally active motilin receptor agonist, on delayed gastric emptying in a canine model of diabetic gastroparesis and to compare these effects with those of cisapride. 2. Moderate hyperglycaemia was induced by a single intravenous injection of a mixture of streptozotocin (30 mg/kg) and alloxan (50 mg/kg). Dogs that maintained moderate hyperglycaemia (fasting plasma glucose 200-300 mg/dL) without insulin treatment were selected and gastric emptying in these dogs was determined by the paracetamol method. 3. One year after the onset of diabetes, there was no difference in the gastric emptying of normal and diabetic dogs. However, after 5 years, the diabetic dogs showed delayed gastric emptying. The motor nerve conduction velocity of the tibial nerve was significantly lower in diabetic dogs compared with normal dogs at both time points. 4. Histopathological examination at the end of the study showed that there were fewer nerve fibres in both dorsal vagal and tibial nerves of diabetic dogs compared with normal dogs. The onset of delayed gastric emptying is thought to have occurred gradually, in parallel with abnormal autonomic nerve function induced by the long period of moderate hyperglycaemia. 5. Oral administration of mitemcinal (0.125, 0.25 or 0.5 mg/kg) dose-dependently accelerated delayed gastric emptying, significant at 0.5 mg/kg, in diabetic dogs, whereas cisapride (1, 3 or 10 mg/kg) had no significant effect. These results add to the existing evidence that mitemcinal is likely to be useful for treating diabetic gastroparesis. PMID:18346169

Onoma, Mitsu; Ozaki, Ken-ichi; Yogo, Kenji; Monnai, Makoto; Muramatsu, Hiroyasu; Kamei, Kenshi; Kawabe, Yoshiki; Hayashi, Shuji; Shiga, Toshihiko; Matsuo, Saori; Suzuki, Masami; Itoh, Zen; Omura, Satoshi; Takanashi, Hisanori

2008-07-01

193

Agonist anti-human CD27 monoclonal antibody induces T cell activation and tumor immunity in human CD27-transgenic mice.  

PubMed

The CD70/CD27 pathway plays a significant role in the control of immunity and tolerance, and previous studies demonstrated that targeting murine CD27 (mCD27) with agonist mAbs can mediate antitumor efficacy. We sought to exploit the potential of this pathway for immunotherapy by developing 1F5, a fully human IgG1 mAb to human CD27 (hCD27) with agonist activity. We developed transgenic mice expressing hCD27 under control of its native promoter for in vivo testing of the Ab. The expression and regulation of hCD27 in hCD27-transgenic (hCD27-Tg) mice were consistent with the understood biology of CD27 in humans. In vitro, 1F5 effectively induced proliferation and cytokine production from hCD27-Tg-derived T cells when combined with TCR stimulation. Administration of 1F5 to hCD27-Tg mice enhanced Ag-specific CD8(+) T cell responses to protein vaccination comparably to an agonist anti-mCD27 mAb. In syngeneic mouse tumor models, 1F5 showed potent antitumor efficacy and induction of protective immunity, which was dependent on CD4(+) and CD8(+) T cells. The requirement of FcR engagement for the agonistic and antitumor activities of 1F5 was demonstrated using an aglycosylated version of the 1F5 mAb. These data with regard to the targeting of hCD27 are consistent with previous reports on targeting mCD27 and provide a rationale for the clinical development of the 1F5 mAb, for which studies in advanced cancer patients have been initiated under the name CDX-1127. PMID:24026078

He, Li-Zhen; Prostak, Naseem; Thomas, Lawrence J; Vitale, Laura; Weidlick, Jeffrey; Crocker, Andrea; Pilsmaker, Catherine D; Round, Sarah M; Tutt, Alison; Glennie, Martin J; Marsh, Henry; Keler, Tibor

2013-10-15

194

Pharmacological evidence of bradykinin regeneration from extended sequences that behave as peptidase–activated B2 receptor agonists  

PubMed Central

While bradykinin (BK) is known to be degraded by angiotensin converting enzyme (ACE), we have recently discovered that Met-Lys-BK-Ser-Ser is paradoxically activated by ACE. We designed and evaluated additional “prodrug” peptides extended around the BK sequence as potential ligands that could be locally activated by vascular or blood plasma peptidases. BK regeneration was estimated using the contractility of the human umbilical vein as model of vascular functions mediated by endogenous B2 receptors (B2Rs) and the endocytosis of the fusion protein B2R-green fluorescent protein (B2R-GFP) expressed in Human Embryonic Kidney 293 cells. Of three BK sequences extended by a C-terminal dipeptide, BK-His-Leu had the most desirable profile, exhibiting little direct affinity for the receptor but a significant one for ACE (as shown by competition of [3H]BK binding to B2R-GFP or of [3H]enalaprilat to recombinant ACE, respectively). The potency of the contractile effect of this analog on the vein was reduced 18-fold by the ACE inhibitor enalaprilat, pharmacologically evidencing BK regeneration in situ. BK-Arg, a potential substrate of arginine carboxypeptidases, had a low affinity for B2Rs and its potency as a contractile agent was reduced 15-fold by tissue treatment with an inhibitor of these enzymes, Plummer’s inhibitor. B2R-GFP internalization in response to 100 nM of the extended peptides recapitulated these findings, as enalaprilat selectively inhibited the effect of BK-His-Leu and Plummer’s inhibitor, that of BK-Arg. The two peptidase inhibitors did not affect BK-induced effects in either assay. The novel C-terminally extended BKs had no or very little affinity for the kinin B1 receptor (competition of [3H]Lys-des-Arg9-BK binding). The feasibility of peptidase-activated B2R agonists is illustrated by C-terminal extensions of the BK sequence. PMID:24639651

Charest-Morin, Xavier; Roy, Caroline; Fortin, Émile-Jacques; Bouthillier, Johanne; Marceau, François

2014-01-01

195

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

PubMed

There is increasing concern about the development of pancreatitis in patients with diabetes mellitus who received long-term glucagon-like peptide-1 (GLP-1) analog treatment. Its pathogenesis is unknown. The effects of GLP-1 agonists on pancreatic endocrine cells are 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 have 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 pancreatitis (AP)/chronic pancreatitis (CP), and the effects of GLP-1 analog on normal PSCs, their ability to stimulate inflammatory mediator secretion or proliferation. GLP-1 receptor (GLP-1R) expression/localization in normal pancreas and pancreatitis (AP/CP) tissues were evaluated with histological/immunohistochemical analysis. PSCs were isolated from male Wistar rats. GLP-1R expression and effects of GLP-1 analog on activated PSCs was examined with real-time PCR, MTS assays and western blotting. In normal pancreas, pancreatic ? cells expressed GLP-1R, with only low expression in acinar cells, whereas in AP or CP, 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 extracellular signal-regulated kinase pathway mediated the PSCs proliferation. GLP-1Rs are expressed in normal pancreas and there is marked enhanced expression in AP/CP. 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/chronic activation of PSCs, which may lead to important effects in the pancreas. PMID:24217090

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

2014-01-01

196

NICOTINE EFFECTS ON THE MOTOR ACTIVITY OF MICE EXPOSED PRENATALLY TO THE NICOTINIC AGONIST ANATOXIN-A.  

EPA Science Inventory

Several studies in the literature have shown that exposure of mice and rats to nicotine early in development alters its effects when the rodents are subsequently challenged with nicotine. Anatoxin-a is a nicotinic agonist produced by several genera of cyanobacteria, and has caus...

197

Novel B subunit mutation causes a slow-channel syndrome by enhancing activation and decreasing the rate of agonist dissociation  

E-print Network

the rate of agonist dissociation Manuel F. Navedo,a Jose´ A. Lasalde-Dominicci,b Carlos A. Ba dissociation constant. In addition, the bV229F mutation produced an increase in calcium permeability in the M2 domain, which line the water-filled ion channel pore, have a pronounced effect on ion channel

Lasalde Dominicc, Jose A. - Department of Biology, Universidad de Puerto Rico

198

Benzocyclobutane, benzocycloheptane and heptene derivatives as melatonin agonists and antagonists.  

PubMed

Two series of analogues were designed, synthesised and evaluated as potential human melatonin type?1 and?2 receptor (hMT1 and hMT2 ) ligands. Their biological effects were assessed by a well-established, specific model of melatonin action, the pigment response of Xenopus laevis melanophores. Compounds containing a benzocyclobutane scaffold and a methoxy group in the "melatonin" orientation were found to be potent agonists, with one of the analogues exhibiting activity comparable to melatonin. In contrast, analogues with a methoxy group in non-melatonin positions or with multiple methoxy groups showed either weaker agonist activity or were antagonists. Benzocycloheptene derivatives with one methoxy group are found to be weak agonists, whereas those with two methoxy groups were found to be antagonists, as were all of the benzocycloheptane derivatives evaluated. The most active compounds were assessed in a human receptor radio ligand binding assay but showed little discrimination between MT1 and MT2 . These results again show that the indole nitrogen of melatonin is not a necessary component for analogue activity and also illustrate that replacement of the indole ring with a 4-membered carbocycle can provide highly active compounds when the methoxy group is in the melatonin position. PMID:25044938

Tsotinis, Andrew; Afroudakis, Pandelis A; Garratt, Peter J; Bocianowska-Zbrog, Alina; Sugden, David

2014-10-01

199

Evaluation of the insulin releasing and antihyperglycaemic activities of GPR55 lipid agonists using clonal beta-cells, isolated pancreatic islets and mice  

PubMed Central

Background and Purpose G-protein coupled receptor (GPR)55 is a novel lipid sensing receptor activated by both cannabinoid endogenous ligands (endocannabinoids) and other non-cannabinoid lipid transmitters. This study assessed the effects of various GPR55 agonists on glucose homeostasis. Experimental Approach Insulin secretion and changes in intracellular Ca2+ and cAMP in response to glucose and a range of GPR55 agonists [endogenous ligands (OEA, PEA), chemically synthetic cannabidiol (CBD) analogues (Abn-CBD, 0–1602), an analogue of rimonabant (AM-251) and antagonist (CBD)] were investigated in clonal BRIN-BD11 cells and mouse pancreatic islets. Cytotoxicity was assessed by LDH release, cellular localization by double-staining immunohistochemistry and in vivo effects assessed in mice. Key Results The most potent and selective GPR55 agonist was the synthetic CBD analogue, Abn-CBD (pEC50 10.33), maximum stimulation of 67% at 10?4?mol·L?1 (P < 0.001) in BRIN-BD11 cells. AM-251 (pEC50 7.0), OEA (pEC50 7.0), 0–1602 (pEC50 7.3) and PEA (pEC50 6.0) stimulated insulin secretion. Results were corroborated by islet studies, with no cytotoxic effects. Concentration-dependent insulin secretion by GPR55 agonists was glucose-sensitive and accompanied by elevations of [Ca2+]i (P < 0.01–P < 0.001) and cAMP (P < 0.05–P < 0.01). GPR55 agonists exhibited insulinotropic and glucose lowering activity in vivo. GPR55 was expressed on BRIN-BD11 cells and confined to islet beta cells with no distribution on alpha cells. Conclusion and Implications These results demonstrate GPR55 is distributed in pancreatic beta cells and is a strong activator of insulin secretion, with glucose-lowering effects in vivo. Development of agents agonizing the GPR55 receptor may have therapeutic potential in the treatment of type 2 diabetes. PMID:23992544

McKillop, A M; Moran, B M; Abdel-Wahab, Y H A; Flatt, P R

2013-01-01

200

Kinetic evidence that desensitized nAChR may promote transitions of active nAChR to desensitized states during sustained exposure to agonists in skeletal muscle  

Microsoft Academic Search

During prolonged exposure of postjunctional nicotinic acetylcholine receptors (nAChR) of skeletal muscle to acetylcholine (ACh), agonist-activated nAChR (nAChRa) gradually fall into a refractory “desensitized” state (nAChRd), which no longer supports the high-conductance channel openings characteristic of the initially active nAChRa. In the present study, the possibility was examined that nAChRd, rather than simply constituting a passive “trap” for nAChRa, may

Arthur A. Manthey

2006-01-01

201

Tesaglitazar, a dual peroxisome proliferator-activated receptor alpha/gamma agonist, reduces atherosclerosis in female low density lipoprotein receptor deficient mice  

PubMed Central

Objective The transcription factors, peroxisome proliferator-activated receptors (PPAR) alpha (?) and gamma (?), which are involved in lipid and glucose homeostasis, also exert modulatory actions on vascular cells where they exhibit anti-inflammatory and anti-proliferative properties. Hence PPAR agonists potentially can affect atherogenesis both via metabolic effects and direct effects on the vessel wall. We tested whether the dual PPAR-?/? agonist, tesaglitazar (TZ), would reduce atherosclerosis in a non-diabetic, atherosclerosis-prone mouse model, independent of effects on plasma lipids. Methods and results Low-density lipoprotein receptor deficient (LDLr ?/?) mice were fed a Western type diet consisting of 21% butterfat and 0.15% cholesterol, with or without TZ 0.5 ?mol/kg of diet, for 12 weeks. TZ reduced atherosclerosis in the female, but not male, LDLr ?/? mice without affecting cholesterol and triglyceride levels, HDL binding to biglycan, or the inflammatory markers serum amyloid A (SAA) and serum amyloid P (SAP). TZ also decreased adiposity in both genders. Conclusions TZ reduced atherosclerosis in the female LDLr?/? mice via lipid-independent mechanisms, probably at least in part by direct actions on the vessels. The body weight changes in these mice are different from the effects of dual PPAR agonists seen in humans. PMID:17214992

Chira, Ebele C.; McMillen, Timothy S.; Wang, Shari; Haw, Antonio; O'Brien, Kevin D.; Wight, Thomas N.; Chait, Alan

2009-01-01

202

Open tubular columns containing the immobilized ligand binding domain of peroxisome proliferator-activated receptors ? and ? for dual agonists characterization by frontal affinity chromatography with MS detection  

PubMed Central

The peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily. In the last years novel PPARs ligands have been identified and these include PPAR?/? dual agonists. To rapidly identify novel PPARs dual ligands, a robust binding assay amenable to high-throughput screening towards PPAR isoforms would be desirable. In this work we describe a parallel assay based on the principles of Frontal Affinity Chromatography coupled to Mass Spectrometry (FAC-MS) that can be used to characterize dual agonists. For this purpose the ligand binding domain of PPAR? receptor was immobilized onto the surface of open tubular capillaries to create new PPAR-alpha-OT columns to be used in parallel with PPAR-gamma-OT columns. The two biochromatographic systems were used in both ranking and Kd experiments towards new ureidofibrate-like dual agonists for subtype selectivity ratio determination. In order to validate the system, the Kd values determined by frontal analysis chromatography were compared to the affinity constants obtained by ITC experiments. The results of this study strongly demonstrate the specific nature of the interaction of the ligands with the two immobilized receptor subtypes. PMID:23466198

Temporini, C.; Pochetti, G.; Fracchiolla, G.; Piemontese, L.; Montanari, R.; Moaddel, R.; Laghezza, A.; Altieri, F.; Cervoni, L.; Ubiali, D.; Prada, E.; Loiodice, F.; Massolini, G.; Calleri, E.

2013-01-01

203

The dual peroxisome proliferator-activated receptor alpha/delta agonist GFT505 exerts anti-diabetic effects in db/db mice without peroxisome proliferator-activated receptor gamma-associated adverse cardiac effects.  

PubMed

We report here the efficacy and safety of GFT505, a novel liver-targeted peroxisome proliferator-activated receptor alpha/delta (PPAR?/?) agonist, in the db/db mouse model of diabetes. Mice were treated with vehicle, GFT505, PPAR? agonist rosiglitazone or dual-PPAR?/? agonist aleglitazar for up to 8 weeks. All compounds comparably reduced fasting glycaemia and HbA1c and improved insulin sensitivity. The glucose-lowering effect of GFT505 was associated with decreased hepatic gluconeogenesis, correlating with reduced expression of gluconeogenic genes. In contrast with the PPAR?-activating drugs, treatment with GFT505 did not affect heart weight and did not increase plasma adiponectin concentrations. This absence of cardiac effects of GFT505 was confirmed after 12?months of administration in cynomolgus monkeys, by the absence of echocardiographic and histological findings. Moreover, long-term GFT505 administration to monkeys induced no change in haematological parameters or in bone marrow differential cell counts. Compared to PPAR?-activating drugs, the dual-PPAR?/? agonist GFT505 therefore shows an improved benefit/risk ratio, treating multiple features of type 2 diabetes without inducing the cardiac side-effects associated with PPAR? activation. PMID:25212694

Hanf, Rémy; Millatt, Lesley J; Cariou, Bertrand; Noel, Benoit; Rigou, Géraldine; Delataille, Philippe; Daix, Valérie; Hum, Dean W; Staels, Bart

2014-11-01

204

Allosteric Modulator ORG27569 Induces CB1 Cannabinoid Receptor High Affinity Agonist Binding State, Receptor Internalization, and Gi Protein-independent ERK1/2 Kinase Activation*  

PubMed Central

The cannabinoid receptor 1 (CB1), a member of the class A G protein-coupled receptor family, is expressed in brain tissue where agonist stimulation primarily activates the pertussis toxin-sensitive inhibitory G protein (Gi). Ligands such as CP55940 ((1R,3R,4R)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4-(3- hydroxypropyl)cyclohexan-1-ol) and ?9-tetrahydrocannabinol are orthosteric agonists for the receptor, bind the conventional binding pocket, and trigger Gi-mediated effects including inhibition of adenylate cyclase. ORG27569 (5-chloro-3-ethyl-1H-indole-2-carboxylic acid [2-(4-piperidin-1-yl-phenyl)ethyl]amide) has been identified as an allosteric modulator that displays positive cooperativity for CP55940 binding to CB1 yet acts as an antagonist of G protein coupling. To examine this apparent conundrum, we used the wild-type CB1 and two mutants, T210A and T210I (D'Antona, A. M., Ahn, K. H., and Kendall, D. A. (2006) Biochemistry 45, 5606–5617), which collectively cover a spectrum of receptor states from inactive to partially active to more fully constitutively active. Using these receptors, we demonstrated that ORG27569 induces a CB1 receptor state that is characterized by enhanced agonist affinity and decreased inverse agonist affinity consistent with an active conformation. Also consistent with this conformation, the impact of ORG27569 binding was most dramatic on the inactive T210A receptor and less pronounced on the already active T210I receptor. Although ORG27569 antagonized CP55940-induced guanosine 5?-3-O-(thio)triphosphate binding, which is indicative of G protein coupling inhibition in a concentration-dependent manner, the ORG27569-induced conformational change of the CB1 receptor led to cellular internalization and downstream activation of ERK signaling, providing the first case of allosteric ligand-biased signaling via CB1. ORG27569-induced ERK phosphorylation persisted even after pertussis toxin treatment to abrogate Gi and occurs in HEK293 and neuronal cells. PMID:22343625

Ahn, Kwang H.; Mahmoud, Mariam M.; Kendall, Debra A.

2012-01-01

205

Enhancement of antitumor effect using dendritic cells activated with natural killer cells in the presence of Toll-like receptor agonist  

PubMed Central

Dendritic cells (DCs) play a role in natural killer (NK) cell activation, while NK cells are also able to activate and mature DCs. Toll-like receptors (TLRs) on the surface of DCs and NK cells induce the maturation and activation of these cells when engaged with their cognate ligand. We investigated to generate potent DCs by maturation with NK cells in the presence of TLR agonist in vitro and tested the efficacy of these DC vaccinations in mouse colon cancer model. The optimal ratios of DCs versus NK cells were 1:1 to 1:2. Immature DCs were mature with NK cells in the presence of lipopolysaccharide, which is TLR4 agonist, and further addition of IL-2 induced phenotypically and functionally mature bone marrow-derived DCs. These potent DCs exhibited not only high expression of several costimulatory molecules and high production of IL-12p40 and IL-12p70, but also high allogeneic T cells stimulatory capacity, and the induction of the high activities to generate tumor-specific CTLs. Consistently, vaccination with these DCs efficiently inhibited CT-26 tumor growth in mouse colon cancer model when compared to other vaccination strategies. Interestingly, combination therapy of these DC-based vaccines and with low-dose cyclophosphamide showed dramatic inhibition effects of tumor growth. These results suggest that the DCs maturated with NK cells in the presence of TLR agonist are potent inducer of antitumor immune responses in mouse model and may provide a new source of DC-based vaccines for the development of immunotherapy against colon cancer. PMID:20386085

Pham, Thanh Nhan Nguyen; Hong, Cheol Yi; Min, Jung-Joon; Rhee, Joon-Haeng; Nguyen, Truc-Anh Thi; Park, Byoung Chul; Yang, Deok-Hwan; Young-Kyu Park; Kim, Hyeong-Rok; Chung, Ik-Joo; Kim, Hyeoung-Joon

2010-01-01

206

An Amyloid-Like C-Terminal Domain of Thrombospondin-1 Displays CD47 Agonist Activity Requiring Both VVM Motifs  

E-print Network

-1170 of human TSP1 referred to as the CBD) has been identified as the site of its interaction with CD47-containing peptides in the C-terminal domain (CBD) of thrombospondin-1 function as CD47 agonists. A recombinant form of the CBD (rCBD) has been expressed that contains both VVM sites and exhibits CD47-dependent binding of C32

Frazier, William A.

207

Partial agonist and neuromodulatory activity of S 24795 for alpha7 nAChR responses of hippocampal interneurons  

Microsoft Academic Search

S 24795 evoked methyllycaconitine-sensitive inward currents in voltage-clamped hippocampal interneurons with maximum amplitude about 14% that of ACh-evoked responses. Experiments with rat ?7 receptors expressed in Xenopus oocytes confirmed that S 24795 is a partial agonist of ?7 nAChR with an EC50 of 34±11?M and Imax of approximately 10% relative to ACh. When 60?M ACh was co-applied to ?7-expressing oocytes

Gretchen Lopez-Hernandez; Andon N. Placzek; Jeffrey S. Thinschmidt; Pierre Lestage; Caryn Trocme-Thibierge; Philippe Morain; Roger L. Papke

2007-01-01

208

Novel potent and selective bile acid derivatives as TGR5 agonists: biological screening, structure-activity relationships, and molecular modeling studies.  

PubMed

TGR5, a metabotropic receptor that is G-protein-coupled to the induction of adenylate cyclase, has been recognized as the molecular link connecting bile acids to the control of energy and glucose homeostasis. With the aim of disclosing novel selective modulators of this receptor and at the same time clarifying the molecular basis of TGR5 activation, we report herein the biological screening of a collection of natural occurring bile acids, bile acid derivatives, and some steroid hormones, which has resulted in the discovery of new potent and selective TGR5 ligands. Biological results of the tested collection of compounds were used to extend the structure-activity relationships of TGR5 agonists and to develop a binary classification model of TGR5 activity. This model in particular could unveil some hidden properties shared by the molecular shape of bile acids and steroid hormones that are relevant to TGR5 activation and may hence be used to address the design of novel selective and potent TGR5 agonists. PMID:18307294

Sato, Hiroyuki; Macchiarulo, Antonio; Thomas, Charles; Gioiello, Antimo; Une, Mizuho; Hofmann, Alan F; Saladin, Régis; Schoonjans, Kristina; Pellicciari, Roberto; Auwerx, Johan

2008-03-27

209

Cannabinoid receptor agonists modulate oligodendrocyte differentiation by activating PI3K/Akt and the mammalian target of rapamycin (mTOR) pathways  

PubMed Central

BACKGROUND AND PURPOSE The endogenous cannabinoid system participates in oligodendrocyte progenitor differentiation in vitro. To determine the effect of synthetic cannabinoids on oligodendrocyte differentiation, we exposed differentiating cultures of oligodendrocytes with cannabinoid CB1, CB2 and CB1/CB2 receptor agonists and antagonists. The response of the PI3K/Akt and the mammalian target of rapamycin (mTOR) signalling pathways were studied as effectors of cannabinoid activity. EXPERIMENTAL APPROACH Purified oligodendrocyte progenitor cells (OPC) obtained from primary mixed glial cell cultures were treated for 48 h with CB1, CB2 and CB1/CB2 receptor agonists (ACEA, JWH133 and HU210, respectively) in the presence or absence of the antagonists AM281 (CB1 receptor) and AM630 (CB2 receptor). Moreover, inhibitors of the phosphatidylinositol 3-kinase (PI3K)/Akt and mTOR pathways (LY294002 and rapamycin, respectively) were used to study the involvement of these pathways on cannabinoid-induced OPC maturation. KEY RESULTS ACEA, JWH133 and HU-210 enhanced OPC differentiation as assessed by the expression of stage specific antigens and myelin basic protein (MBP). Moreover, this effect was blocked by the CB receptor antagonists. ACEA, JWH133 and HU210 induced a time-dependent phosphorylation of Akt and mTOR, whereas the inhibitors of PI3K/Akt (LY294002) or of mTOR (rapamycin) reversed the effects of HU-210 on oligodendrocyte differentiation and kinase activation. CONCLUSIONS AND IMPLICATIONS Activation of cannabinoid CB1 or CB2 receptors with selective agonists accelerated oligodendrocyte differentiation through the mTOR and Akt signalling pathways. LINKED ARTICLES This article is part of a themed issue on Cannabinoids in Biology and Medicine. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.163.issue-7 PMID:21480865

Gomez, O; Sanchez-Rodriguez, A; Le, MQU; Sanchez-Caro, C; Molina-Holgado, F; Molina-Holgado, E

2011-01-01

210

Differential Effects of the Toll-Like Receptor 2 Agonists, PGN and Pam3CSK4 on Anti-IgE Induced Human Mast Cell Activation  

PubMed Central

Mast cells are pivotal in the pathogenesis of allergy and inflammation. In addition to the classical IgE-dependent mechanism involving crosslinking of the high-affinity receptor for IgE (Fc?RI), mast cells are also activated by Toll-like receptors (TLRs) which are at the center of innate immunity. In this study, we demonstrated that the response of LAD2 cells (a human mast cell line) to anti-IgE was altered in the presence of the TLR2 agonists peptidoglycan (PGN) and tripalmitoyl-S-glycero-Cys-(Lys)4 (Pam3CSK4). Pretreatment of PGN and Pam3CSK4 inhibited anti-IgE induced calcium mobilization and degranulation without down-regulation of Fc?RI expression. Pam3CSK4 but not PGN acted in synergy with anti-IgE for IL-8 release when the TLR2 agonist was added simultaneously with anti-IgE. Studies with inhibitors of key enzymes implicated in mast cell signaling revealed that the synergistic release of IL-8 induced by Pam3CSK4 and anti-IgE involved ERK and calcineurin signaling cascades. The differential modulations of anti-IgE induced mast cell activation by PGN and Pam3CSK4 suggest that dimerization of TLR2 with TLR1 or TLR6 produced different modulating actions on Fc?RI mediated human mast cell activation. PMID:25398056

Yu, Yangyang; Yip, Kwok Ho; Tam, Issan Yee San; Sam, Sze Wing; Ng, Chun Wai; Zhang, Wei; Lau, Hang Yung Alaster

2014-01-01

211

Structural motifs of importance for the constitutive activity of the orphan 7TM receptor EBI2: analysis of receptor activation in the absence of an agonist.  

PubMed

The Epstein-Barr induced receptor 2 (EBI2) is a lymphocyte-expressed orphan seven transmembrane-spanning (7TM) receptor that signals constitutively through Galphai, as shown, for instance by guanosine 5'-O-(3-thio)triphosphate incorporation. Two regions of importance for the constitutive activity were identified by a systematic mutational analysis of 29 residues in EBI2. The cAMP response element-binding protein transcription factor was used as a measure of receptor activity and was correlated to the receptor surface expression. PheVI:13 (Phe257), and the neighboring CysVI:12 (Cys256), in the conserved CW/FxP motif in TM 6, acted as negative regulators as Ala substitutions at these positions increased the constitutive activity 5.7- and 2.3-fold, respectively, compared with EBI2 wild type (wt). In contrast, ArgII:20 (Arg87) in TM-2 acted as a positive regulator, as substitution to Ala, but not to Lys, decreased the constitutive activity more than 7-fold compared with wt EBI2. IleIII:03 (Ile106) is located only 4 A from ArgII:20, and a favorable electrostatic interaction with ArgII:20 was created by introduction of Glu in III:03, given that the activity increased to 4.4-fold of that wt EBI2. It is noteworthy that swapping these charges by introduction of Glu in II:20 and Arg in III:03 resulted in a 2.7-fold increase compared with wt EBI2, thereby rescuing the two signaling-deficient single mutations, which exhibited a 3.8- to 4.5-fold decrease in constitutive activity. The uncovering of these molecular mechanisms for EBI2 activation is important from a drug development point of view, in that it may facilitate the rational design and development of small-molecule inverse agonists against EBI2 of putative importance as antiviral- or immune modulatory therapy. PMID:18628402

Benned-Jensen, Tau; Rosenkilde, Mette M

2008-10-01

212

Structural Dynamics of Actin during Active Interaction with Myosin: Different Effects of Weakly and Strongly Bound Myosin Heads  

E-print Network

Structural Dynamics of Actin during Active Interaction with Myosin: Different Effects of Weakly energy transfer, FRET) to detect the effects of weakly bound myosin S1 on actin during the actomyosin ATPase cycle. The changes in actin were reported by (a) a phosphorescent probe (ErIA) attached to Cys 374

Thomas, David D.

213

Structure-activity relationship study of betulinic acid, a novel and selective TGR5 agonist, and its synthetic derivatives: potential impact in diabetes.  

PubMed

We describe here the biological screening of a collection of natural occurring triterpenoids against the G protein-coupled receptor TGR5, known to be activated by bile acids and which mediates some important cell functions. This work revealed that betulinic (1), oleanolic (2), and ursolic acid (3) exhibited TGR5 agonist activity in a selective manner compared to bile acids, which also activated FXR, the nuclear bile acid receptor. The most potent natural triterpenoid betulinic acid was chosen as a reference compound for an SAR study. Hemisyntheses were performed on the betulinic acid scaffold, and we focused on structural modifications of the C-3 alcohol, the C-17 carboxylic acid, and the C-20 alkene. In particular, structural variations around the C-3 position gave rise to major improvements of potency exemplified with derivatives 18 dia 2 (RG-239) and 19 dia 2. The best derivative was tested in vitro and in vivo, and its biological profile is discussed. PMID:19911773

Genet, Cédric; Strehle, Axelle; Schmidt, Céline; Boudjelal, Geoffrey; Lobstein, Annelise; Schoonjans, Kristina; Souchet, Michel; Auwerx, Johan; Saladin, Régis; Wagner, Alain

2010-01-14

214

Quantitative structure-activity relationships for weak acid respiratory uncouplers to Vibrio fisheri  

SciTech Connect

Acute toxicity values of 16 organic compounds thought to elicit their response via the weak acid respiratory uncoupling mechanism of toxic action were secured from the literature. Regression analysis of toxicities revealed that a measured 5-min V. fisheri potency value can be used as a surrogate for the 30-min value. Regression analysis of toxicity versus hydrophobicity, measured as the 1-octanol/water partition coefficient (log K{sub ow}), was used to formulate a quantitative structure-activity relationship (QSAR). The equation log pT{sub 30}{sup {minus}1} = 0.489(log K{sub ow}) + 0.126 was found to be a highly predictive model. This V. fisheri QSAR is statistically similar to QSARs generated from weak acid uncoupler potency data for Pimephales promelas survivability and Tetrahymena pyriformis population growth impairment. This work, therefore, suggests that the weak acid respiratory uncoupling mechanism of toxic action is present in V. fisheri, and as such is not restricted to mitochondria-containing organisms.

Schultz, T.W. [Univ. of Tennessee, Knoxville, TN (United States). Coll. of Veterinary Medicine; Cronin, M.T.D. [Liverpool John Moores Univ. (United Kingdom). School of Pharmacy and Chemistry

1997-02-01

215

Skeletal muscle weakness, exercise tolerance and physical activity in adults with cystic fibrosis.  

PubMed

The aim of the present study was to investigate the prevalence of muscle weakness and the importance of physical inactivity in cystic fibrosis (CF), and its relationship to exercise tolerance and muscle strength. Exercise tolerance, skeletal and respiratory muscle strength were studied in a group of 64 adults with CF (age 26+/-8 yrs, FEV(1 % predicted) 65+/-19) and in 20 age-matched controls. Physical activity (PA) was assessed in 20 patients and all controls. Quadriceps muscle weakness was present in 56% of the patients. Peak oxygen uptake and 6-min walking distance were below normal in 89 and 75% of patients, respectively. Respiratory muscle strength was normal. The differences remained after correcting for PA. Quadriceps force was correlated to the 6-min walking distance but not to peak oxygen uptake. "Mild" PA (>3 metabolic equivalents (METS)) and the number of steps overlapped with controls, but CF patients had less moderate PA (>4.8 METS). Moderate PA was related to peak oxygen uptake and quadriceps force. Skeletal muscle weakness and exercise intolerance are prevalent in cystic fibrosis. Physical inactivity is a factor significantly contributing to exercise tolerance and skeletal muscle force in adults with cystic fibrosis, but these impairments are in excess to that expected from physical inactivity only. PMID:18715878

Troosters, T; Langer, D; Vrijsen, B; Segers, J; Wouters, K; Janssens, W; Gosselink, R; Decramer, M; Dupont, L

2009-01-01

216

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist inhibits transforming growth factor-beta1 and matrix production in human dermal fibroblasts.  

PubMed

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists are increasingly used in patients with diabetes, and some studies have suggested a beneficial effect on organ fibrosis, but their effects on dermal cell growth and extracellular matrix (ECM) turnover are unknown. To investigate the effect of the PPAR-gamma agonist troglitazone on cell growth and matrix production in human dermal fibroblasts (HDF), HDF were cultured and grown in a different concentration of troglitazone. PPAR-gamma expression and matrix production were measured in HDF in the presence of troglitazone. The mRNA expressions of TGF-beta1, collagen I (Col I) and fibronectin (FN) were determined by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR). The protein of transforming growth factor-beta1 (TGF-beta1) was determined by enzyme-linked immunosorbent assay (ELISA) and proteins of Col I and FN were determined by Western blotting. The mRNA expression of TGF-beta1, Col I and FN were significantly decreased in HDF in 15-30 micromol l(-1) troglitazone compared to the control group with Dulbecco's modified Eagle's medium (P<0.01). An obvious decrease of TGF-beta1 protein was found in troglitazone-treated groups as compared to the control group (P<0.05). Exposure of HDF to troglitazone reduced col I secretion (P<0.05), and fibronectin secretion (P<0.05). This study suggests that PPAR-gamma agonist will provide a novel approach with therapeutic potential in dermal fibrosis, such as hypertrophic scar, keloid and so on. PMID:19617014

Zhang, Guo-You; Cheng, Tao; Zheng, Ming-Hua; Yi, Cheng-Gang; Pan, Hua; Li, Zhi-Jie; Chen, Xing-Long; Yu, Qing; Jiang, Liang-Fu; Zhou, Fei-Ya; Li, Xiao-Yang; Yang, Jing-Quan; Chu, Ting-Gang; Gao, Wei-Yang

2010-07-01

217

Neuroprotective Potential of Peroxisome Proliferator Activated Receptor-? Agonist in Cognitive Impairment in Parkinson's Disease: Behavioral, Biochemical, and PBPK Profile  

PubMed Central

Parkinson's disease (PD) is a common neurodegenerative disorder affecting 1% of the population by the age of 65 years and 4-5% of the population by the age of 85 years. PD affects functional capabilities of the patient by producing motor symptoms and nonmotor symptoms. Apart from this, it is also associated with a higher risk of cognitive impairment that may lead to memory loss, confusion, and decreased attention span. In this study, we have investigated the effect of fenofibrate, a PPAR-? agonist in cognitive impairment model in PD. Bilateral intranigral administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (100?µg/1?µL/side) produced significant cognitive dysfunctions. Fenofibrate treatment at 10, 30, and 100?mg/kg for twenty-five days was found to be neuroprotective and improved cognitive impairment in MPTP-induced PD model as evident from behavioral, biochemical (MDA, GSH, TNF-?, and IL-6), immunohistochemistry (TH), and DNA fragmentation (TUNEL positive cells) studies. Further, physiologically based pharmacokinetic (PBPK) modeling study was performed using GastroPlus to characterize the kinetics of fenofibric acid in the brain. A good agreement was found between pharmacokinetic parameters obtained from the actual and simulated plasma concentration-time profiles of fenofibric acid. Results of this study suggest that PPAR-? agonist (fenofibrate) is neuroprotective in PD-induced cognitive impairment. PMID:24693279

Das, Nihar R.; Gangwal, Rahul P.; Damre, Mangesh V.; Sangamwar, Abhay T.; Sharma, Shyam S.

2014-01-01

218

Orientation and Electrochemical Oxidation of Hydroquinone Chemisorbed on Platinum Electrodes in Various Weakly Surface-Active Supporting Electrolytes.  

National Technical Information Service (NTIS)

Studies on the adsorption, orientation and electrochemical oxidation of hydroquinone at smooth polycrystalline Pt electrodes in aqueous solutions of weakly surface-active electrolytes are reported. The electrolytes were compared with respect to how they i...

M. P. Soriaga, V. K.F. Chia, J. H. White, D. Song, A.T. Hubbard

1984-01-01

219

Sigma-2 receptor agonists activate a novel apoptotic pathway and potentiate antineoplastic drugs in breast tumor cell lines.  

PubMed

We have reported previously that sigma-2 receptors are expressed in high densities in a variety of tumor cell types (B. J. Vilner et al., Cancer Res., 55: 408-413, 1995) and that various sigma ligands have cytotoxic effects (B. J. Vilner et al., J. Neurosci., 15: 117-134, 1995). Other investigators have demonstrated increased expression of sigma-2 receptors in rapidly proliferating tumors (R. H. Mach et al., Cancer Res., 57: 156-161, 1997) and the ability of some sigma ligands to inhibit proliferation (P. J. Brent and G. T. Pang, Eur. J. Pharmacol., 278: 151-160, 1995). We demonstrate here the ability of sigma-2 receptor agonists to induce cell death by a mechanism consistent with apoptosis. In breast tumor cell lines that are sensitive (MCF-7) and resistant (MCF-7/Adr-, T47D, and SKBr3) to antineoplastic agents, incubation with the sigma-2 subtype-selective agonists CB-64D and CB-184 produced dose-dependent cytotoxicity (measured by lactate dehydrogenase release into medium). The EC(50) for this response was similar across cell lines, irrespective of p53 genotype and drug-resistance phenotype. CB-64D and the subtype nonselective sigma-2 agonists haloperidol and reduced haloperidol induced terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining in MCF-7 and T47D cells, indicating that cell death occurs via apoptosis. Apoptosis was also indicated by increases in Annexin V binding caused by CB-64D. In MCF-7 cells, cytotoxicity and Annexin V binding induced by the antineoplastics doxorubicin and actinomycin D was partially or completely abrogated by certain specific and general inhibitors of caspases. In contrast, caspase inhibitors had no effect on sigma-2 receptor-mediated (CB-64D and CB-184) cytotoxicity or Annexin V binding. Marked potentiation of cytotoxicity was observed when a subtoxic dose of CB-184 was combined with doxorubicin or actinomycin D, both in drug-sensitive (MCF-7) and drug-resistant (MCF-7/Adr-) cell lines. Haloperidol potentiated doxorubicin only in drug-resistant cells. These findings suggest the involvement of a novel p53- and caspase-independent apoptotic pathway used by sigma-2 receptors, which is distinct from mechanisms used by some DNA-damaging, antineoplastic agents and other apoptotic stimuli. These observations further suggest that sigma-2 receptors may be targets that can be therapeutically exploited in the treatment of both drug-sensitive and drug-resistant metastatic tumors. PMID:11782394

Crawford, Keith W; Bowen, Wayne D

2002-01-01

220

Allosteric Switching of Agonist/Antagonist Activity by a Single Point Mutation in the Interluekin-1 Receptor Antagonist, IL-1Ra  

PubMed Central

The pleiotropic pro-inflammatory cytokine interleukin (IL)-1? has co-evolved with a competitive inhibitor, IL-1 receptor antagonist (IL-1Ra). IL-1? initiates cell signaling by binding the IL-1 receptor (IL-1R) whereas IL-1Ra acts as an antagonist, blocking receptor signaling. The current paradigm for agonist/antagonist functions for these two proteins is based on the receptor–ligand interaction observed in the crystal structures of the receptor–ligand complexes. While IL-1Ra and IL-1? are structurally homologous, IL-1Ra engages only two of the three extracellular domains of the receptor, whereas IL-1? engages all three. We find that an allosteric functional switch exists within a highly conserved pocket of residues, residues 111–120. This region is maintained across all IL-1 family members and serves as a hydrophobic mini-core for IL-1? folding. A key difference across species is a conserved aromatic residue at position 117 in IL-1?, versus a conserved cysteine in IL-1Ra at the analogous position, 116. We find that the replacement of C116 with a phenylalanine switches the protein from an antagonist to an agonist despite the distant location of C116 relative to receptor interaction sites. These results suggest new ways to develop designer cytokine activity into the ?-trefoil fold and may be of general use in regulation of this large family of signaling proteins. PMID:23499887

Hailey, Kendra L.; Capraro, Dominique T.; Barkho, Sulyman; Jennings, Patricia A.

2013-01-01

221

Total synthesis and pharmacological characterization of solomonsterol A, a potent marine pregnane-X-receptor agonist endowed with anti-inflammatory activity.  

PubMed

Recently, we reported the identification of a novel class of pregnane-X-receptor (PXR) agonists, solomonsterols A and B, isolated from the marine sponge Theonella swinhoei. Preliminary pharmacological studies demonstrated that these natural compounds are potential leads for the treatment of human disorders characterized by dysregulation of innate immunity. In this article, we describe the first total synthesis of solomonsterol A and its in vivo characterization in animal models of colitis. Using transgenic mice expressing the human PXR, we found that administration of synthetic solomonsterol A effectively protects against development of clinical signs and symptoms of colitis and reduced the generation of TNF?, a signature cytokine for this disorder. In addition, we have provided the first evidence that solomonsterol A might act by triggering the expression of TGF? and IL-10, potent counter-regulatory cytokines in inflammatory bowel diseases (IBD). Finally, we have shown that solomonsterol A inhibits NF-?B activation by a PXR dependent mechanism. In summary, solomonsterol A is a marine PXR agonist that holds promise in the treatment of inflammation-driven immune dysfunction in clinical settings. PMID:21599020

Sepe, Valentina; Ummarino, Raffaella; D'Auria, Maria Valeria; Mencarelli, Andrea; D'Amore, Claudio; Renga, Barbara; Zampella, Angela; Fiorucci, Stefano

2011-07-14

222

Cannabinoid receptor-2 (CB2) agonist ameliorates colitis in IL-10{sup ?/?} mice by attenuating the activation of T cells and promoting their apoptosis  

SciTech Connect

Inflammatory bowel disease (IBD) is a chronic intestinal inflammation caused by hyperactivated effector immune cells that produce pro-inflammatory cytokines. Recent studies have shown that the cannabinoid system may play a critical role in mediating protection against intestinal inflammation. However, the effect of cannabinoid receptor induction after chronic colitis progression has not been investigated. Here, we investigate the effect of cannabinoid receptor-2 (CB2) agonist, JWH-133, after chronic colitis in IL-10{sup ?/?} mice. JWH-133 effectively attenuated the overall clinical score, and reversed colitis-associated pathogenesis and decrease in body weight in IL-10{sup ?/?} mice. After JWH-133 treatment, the percentage of CD4{sup +} T cells, neutrophils, mast cells, natural killer (NK1.1) cells, and activated T cells declined in the intestinal lamina propria (LP) and mesenteric lymph nodes (MLN) of mice with chronic colitis. JWH-133 was also effective in ameliorating dextran sodium sulfate (DSS)-induced colitis. In this model, JWH-133 reduced the number and percentage of macrophages and IFN-? expressing cells that were induced during colitis progression. Treatment with aminoalkylindole 6-iodo-pravadoline (AM630), a CB2 receptor antagonist, reversed the colitis protection provided by JWH-133 treatment. Also, activated T cells were found to undergo apoptosis following JWH-133 treatment both in-vivo and in-vitro. These findings suggest that JWH-133 mediates its effect through CB2 receptors, and ameliorates chronic colitis by inducing apoptosis in activated T cells, reducing the numbers of activated T cells, and suppressing induction of mast cells, NK cells, and neutrophils at sites of inflammation in the LP. These results support the idea that the CB2 receptor agonists may serve as a therapeutic modality against IBD. -- Highlights: ? JWH-133, a cannnabinoid receptor-2 agonist ameliorates experimental colitis. ? JWH-133 suppressed inflammation and toxicity to colon by inducing T cell apoptosis. ? JWH-133 decreased mast cells, macrophages, NK cells, IFN-?{sup +} cells in the LPL. ? AM630, a cannnabinoid receptor-2 antagonist inverted the colitis defense of JWH-133. ? Cannnabinoid receptor-2 may serve as a novel therapeutic target for IBD.

Singh, Udai P.; Singh, Narendra P. [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States)] [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States); Singh, Balwan [National Primate Research Center, Emory University, Atlanta GA 30329 (United States)] [National Primate Research Center, Emory University, Atlanta GA 30329 (United States); Price, Robert L. [Department of Cell and Developmental Biology, University of South Carolina, Columbia, SC 29208 (United States)] [Department of Cell and Developmental Biology, University of South Carolina, Columbia, SC 29208 (United States); Nagarkatti, Mitzi [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States)] [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States); Nagarkatti, Prakash S., E-mail: Prakash.Nagarkatti@uscmed.sc.edu [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States)

2012-01-15

223

Synthesis and structure-activity relationships of long-acting beta2 adrenergic receptor agonists incorporating arylsulfonamide groups.  

PubMed

A series of saligenin alkoxyalkylphenylsulfonamide beta(2) adrenoceptor agonists were prepared by reacting a protected saligenin oxazolidinone with alkynyloxyalkyl bromides, followed by Sonogashira reaction, hydrogenation, and deprotection. The meta-substituted primary sulfonamide was more potent than the para- and the ortho-analogues. Primary sulfonamides were more potent than the secondary and tertiary analogues. The onset and duration of action in vitro of selected compounds was assessed on isolated superfused guinea pig trachea. Sulfonamide 29b had the best profile of potency, selectivity, onset, and duration of action on both guinea pig trachea and human bronchus. Furthermore, 29b was found to have low oral bioavailability in rat and dog and also to have long duration of action in an in vivo model of bronchodilation. Crystalline salts of 29b were identified that had suitable properties for inhaled administration. A proposed binding mode for 29b to the beta(2)-receptor is presented. PMID:19317397

Procopiou, Panayiotis A; Barrett, Victoria J; Bevan, Nicola J; Biggadike, Keith; Butchers, Peter R; Coe, Diane M; Conroy, Richard; Edney, Dean D; Field, Rita N; Ford, Alison J; Guntrip, Stephen B; Looker, Brian E; McLay, Iain M; Monteith, Michael J; Morrison, Valerie S; Mutch, Peter J; Richards, Stephen A; Sasse, Rosemary; Smith, Claire E

2009-04-23

224

Effects of ATPM-ET, a novel ? agonist with partial ? activity, on physical dependence and behavior sensitization in mice  

PubMed Central

Aim: To investigate the effects of ATPM-ET [(?)-3-N-Ethylaminothiazolo [5,4-b]-N-cyclopropylmethylmorphinan hydrochloride] on physical dependence and behavioral sensitization to morphine in mice. Methods: The pharmacological profile of ATPM-ET was characterized using competitive binding and GTP?S binding assays. We then examined the antinociceptive effects of ATPM-ET in the hot plate test. Morphine dependence assay and behavioral sensitization assay were used to determine the effect of ATPM-ET on physical dependence and behavior sensitization to morphine in mice. Results: The binding assay indicated that ATPM-ET ATPM-ET exhibited a high affinity to both ?- and ?-opioid receptors with Ki values of 0.15 nmol/L and 4.7 nmol/L, respectively, indicating it was a full ?-opioid receptor agonist and a partial ?-opioid receptor agonist. In the hot plate test, ATPM-ET produced a dose-dependent antinociceptive effect, with an ED50 value of 2.68 (2.34–3.07) mg/kg. Administration of ATPM-ET (1 and 2 mg/kg, sc) prior to naloxone (3.0 mg/kg, sc) injection significantly inhibited withdrawal jumping of mice. In addition, ATPM-ET (1 and 2 mg/kg, sc) also showed a trend toward decreasing morphine withdrawal-induced weight loss. ATPM-ET (1.5 and 3 mg/kg, sc) 15 min before the morphine challenge significantly inhibited the morphine-induced behavior sensitization (P<0.05). Conclusion: ATPM-ET may have potential as a therapeutic agent for the treatment of drug abuse. PMID:21102484

Sun, Jian-feng; Wang, Yu-hua; Li, Fu-ying; Lu, Gang; Tao, Yi-min; Cheng, Yun; Chen, Jie; Xu, Xue-jun; Chi, Zhi-qiang; Neumeyer, John L; Zhang, Ao; Liu, Jing-gen

2010-01-01

225

A novel PPAR{gamma} agonist, KR62776, suppresses RANKL-induced osteoclast differentiation and activity by inhibiting MAP kinase pathways  

SciTech Connect

We investigated the effects of a novel peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) agonist, KR62776, on osteoclast differentiation and function, and on the underlying signaling pathways. KR62776 markedly suppressed differentiation into osteoclasts in various osteoclast model systems, including bone marrow mononuclear (BMM) cells and a co-culture of calvarial osteoblasts and BMM cells. KR62776 suppressed the activation of tartrate-resistant acid phosphatase (TRAP) and the expression of genes associated with osteoclast differentiation, such as TRAP, dendritic cell-specific transmembrane protein (DC-STAMP), and osteoclast-associated receptor (OSCAR). Furthermore, KR62776 reduced resorption pit formation in osteoclasts, and down-regulated genes essential for osteoclast activity, such as Src and {alpha}v{beta}3 integrin. An analysis of a signaling pathway showed that KR62776 inhibited the receptor activator of nuclear factor-{kappa}B ligand (RANKL)-induced activation of p38 mitogen-activated protein kinase (p38MAPK), extracellular regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and nuclear factor-{kappa}B (NF-{kappa}B). Together, these results demonstrate that KR62776 negatively affects osteoclast differentiation and activity by inhibiting the RANKL-induced activation of MAP kinases and NF-{kappa}B.

Park, Ju-Young [Skeletal Diseases Genome Research Center, Kyungpook National University Hospital, Daegu (Korea, Republic of); Department of Biochemistry, School of Medicine, Kyungpook National University, Daegu (Korea, Republic of); Bae, Myung-Ae; Cheon, Hyae Gyeong; Kim, Sung Soo [Center for Metabolic Syndrome Therapeutics, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Hong, Jung-Min; Kim, Tae-Ho [Skeletal Diseases Genome Research Center, Kyungpook National University Hospital, Daegu (Korea, Republic of); Choi, Je-Yong [Skeletal Diseases Genome Research Center, Kyungpook National University Hospital, Daegu (Korea, Republic of); Department of Biochemistry, School of Medicine, Kyungpook National University, Daegu (Korea, Republic of); Kim, Sang-Hyun [Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu (Korea, Republic of); Lim, Jiwon [Department of Oral Pathology, IHBR, School of Dentistry, Kyungpook National University, Daegu (Korea, Republic of); Choi, Chang-Hyuk [Department of Orthopaedic Surgery, School of Medicine, Catholic University of Daegu, Daegu (Korea, Republic of); Shin, Hong-In [Department of Oral Pathology, IHBR, School of Dentistry, Kyungpook National University, Daegu (Korea, Republic of); Kim, Shin-Yoon [Skeletal Diseases Genome Research Center, Kyungpook National University Hospital, Daegu (Korea, Republic of); Department of Orthopaedic Surgery, School of Medicine, Kyungpook National University, Daegu (Korea, Republic of)], E-mail: syukim@knu.ac.kr; Park, Eui Kyun [Skeletal Diseases Genome Research Center, Kyungpook National University Hospital, Daegu (Korea, Republic of); Department of Oral Pathology, IHBR, School of Dentistry, Kyungpook National University, Daegu (Korea, Republic of)], E-mail: epark@knu.ac.kr

2009-01-16

226

Agonist activation of p42 and p44 mitogen-activated protein kinases following expression of the mouse delta opioid receptor in Rat-1 fibroblasts: effects of receptor expression levels and comparisons with G-protein activation.  

PubMed Central

Rat-1 fibroblasts were transfected with a cDNA encoding the mouse delta opioid receptor. Two separate clones, D2 (which expressed some 6 pmol of the receptor/mg of membrane protein) and DOE (which expressed some 0.2 pmol/mg of membrane protein), were examined in detail. With membranes from both clones, the opioid agonist [D-Ala2]leucine enkephalin (DADLE) caused stimulation of high-affinity GTPase activity and of the binding of guanosine 5'-[gamma-[35S]thio]triphosphate, and inhibition of forskolin-amplified adenylate cyclase activity. DADLE also induced phosphorylation and activation of both the p42MAPK (42 kDa isoform) and p44MAPK (44 kDa isoform) members of the mitogen-activated protein kinase (MAP kinase) family. All of these effects of DADLE were prevented in both clones by pretreatment of the cells with pertussis toxin. The maximal response that could be produced by DADLE in direct assays of G-protein activation were substantially greater in clone D2 than in clone DOE, but in both clones essentially full phosphorylation of both p42MAPK and p44MAPK could be achieved. EC50 values for DADLE stimulation of GTPase activity and for activation of p44MAPK were substantially lower in clone D2 than in clone DOE. Moreover, in both clones the EC50 value for DADLE stimulation of p44MAPK was substantially lower than that for stimulation of GTPase activity, and the Hill coefficients for agonist activation of p44MAPK (h > 1) displayed marked co-operativity whereas those for G-protein activation did not (h 0.8-1.0). DADLE activation of p44MAPK showed more sustained kinetics in clone D2 than in clone DOE. By contrast, lysophosphatidic acid, acting at an endogenously expressed G-protein-coupled receptor, also activated p44MAPK in both clones in a pertussis toxinsensitive manner, but both the kinetics and the concentration-response curve for activation of p44MAPK by this ligand were similar. As with other systems, maintained cellular levels of a cAMP analogue prevented the effects of both G-protein-coupled receptors on activation of p44MAPK. These results demonstrate for the first time that an opioid receptor, at least when expressed in Rat-1 fibroblasts, is able to initiate activation of the MAP kinase cascade in a G1-dependent manner, and show that only a very small proportion of the cellular G1 population is required to be activated to result in full phosphorylation of the p42MAPK and p44MAPK MAP kinases. PMID:8947492

Burt, A R; Carr, I C; Mullaney, I; Anderson, N G; Milligan, G

1996-01-01

227

PPAR Agonists and Cardiovascular Disease in Diabetes  

PubMed Central

Peroxisome proliferators activated receptors (PPARs) are ligand-activated nuclear transcription factors that play important roles in lipid and glucose homeostasis. To the extent that PPAR agonists improve diabetic dyslipidaemia and insulin resistance, these agents have been considered to reduce cardiovascular risk. However, data from murine models suggests that PPAR agonists also have independent anti-atherosclerotic actions, including the suppression of vascular inflammation, oxidative stress, and activation of the renin angiotensin system. Many of these potentially anti-atherosclerotic effects are thought to be mediated by transrepression of nuclear factor-kB, STAT, and activator protein-1 dependent pathways. In recent clinical trials, PPAR? agonists have been shown to be effective in the primary prevention of cardiovascular events, while their cardiovascular benefit in patients with established cardiovascular disease remains equivocal. However, the use of PPAR? agonists, and more recently dual PPAR?/? coagonists, has been associated with an excess in cardiovascular events, possibly reflecting unrecognised fluid retention with potent agonists of the PPAR? receptor. Newer pan agonists, which retain their anti-atherosclerotic activity without weight gain, may provide one solution to this problem. However, the complex biologic effects of the PPARs may mean that only vascular targeted agents or pure transrepressors will realise the goal of preventing atherosclerotic vascular disease. PMID:18288280

Calkin, Anna C.; Thomas, Merlin C.

2008-01-01

228

Correlating AMPA-Receptor Activation and Cleft Closure Across Subunits: Crystal Structures of the GluR4 Ligand-Binding Domain in Complex with Full and Partial Agonists  

PubMed Central

AMPA receptors are glutamate-gated ion channels that are essential mediators of synaptic signals in the central nervous system. They form tetramers that are assembled as combinations of the subunits GluR1-4, each of which contains a ligand-binding domain (LBD). Crystal structures of the GluR2 LBD have revealed an agonist-binding cleft, which is located between two lobes and which acts like a Venus flytrap. In general, agonist efficacy is correlated with the extent of cleft closure. However, recent observations show that cleft closure is not the sole determinant of relative efficacy for glutamate receptors. In addition, these studies have focused on the GluR2 subunit, which is the specific target of a physiologically important RNA-editing modification in vivo. We therefore wished to test the generality of the cleft closure:efficacy correlation for other AMPA-R subunits. Here, we present crystal structures of the GluR4flip LBD in complex with both full and partial agonists. As for GluR2, both agonists stabilize a closed-cleft conformation, and the partial agonist induces a smaller cleft closure than the full agonist. However, a detailed analysis of LBD:kainate interactions reveals the importance of subtle backbone conformational changes in the ligand-binding pocket in determining the magnitude of agonist-associated conformational changes. Furthermore, the GluR4 subunit exhibits a different correlation between receptor activation and LBD cleft closure than does GluR2. PMID:19102704

Gill, Avinash; Birdsey-Benson, Amanda; Jones, Brian L.; Henderson, Leslie P.; Madden, Dean R.

2009-01-01

229

Apo2L/TRAIL and the death receptor 5 agonist antibody AMG 655 cooperate to promote receptor clustering and antitumor activity.  

PubMed

Death receptor agonist therapies have exhibited limited clinical benefit to date. Investigations into why Apo2L/TRAIL and AMG 655 preclinical data were not predictive of clinical response revealed that coadministration of Apo2L/TRAIL with AMG 655 leads to increased antitumor activity in vitro and in vivo. The combination of Apo2L/TRAIL and AMG 655 results in enhanced signaling and can sensitize Apo2L/TRAIL-resistant cells. Structure determination of the Apo2L/TRAIL-DR5-AMG 655 ternary complex illustrates how higher order clustering of DR5 is achieved when both agents are combined. Enhanced agonism generated by combining Apo2L/TRAIL and AMG 655 provides insight into the limited efficacy observed in previous clinical trials and suggests testable hypotheses to reconsider death receptor agonism as a therapeutic strategy. PMID:25043603

Graves, Jonathan D; Kordich, Jennifer J; Huang, Tzu-Hsuan; Piasecki, Julia; Bush, Tammy L; Sullivan, Timothy; Foltz, Ian N; Chang, Wesley; Douangpanya, Heather; Dang, Thu; O'Neill, Jason W; Mallari, Rommel; Zhao, Xiaoning; Branstetter, Daniel G; Rossi, John M; Long, Alexander M; Huang, Xin; Holland, Pamela M

2014-08-11

230

Molecular Engineering of Organophosphate Hydrolysis Activity from a Weak Promiscuous Lactonase Template  

PubMed Central

Rapid evolution of enzymes provides unique molecular insights into the remarkable adaptability of proteins and helps to elucidate the relationship between amino acid sequence, structure and function. We interrogated the evolution of the phosphotriesterase from Pseudomonas diminuta (PdPTE), which hydrolyzes synthetic organophosphates with remarkable catalytic efficiency. PTE is thought to be an evolutionarily “young” enzyme and it has been postulated that it has evolved from members of the phosphotriesterase-like lactonase (PLL) family that show promiscuous organophosphate degrading activity. Starting from a weakly promiscuous PLL scaffold (Dr0930 from Deinococcus radiodurans), we designed an extremely efficient organophosphate hydrolase (OPH) with broad substrate specificity using rational and random mutagenesis in combination with in vitro activity screening. The OPH activity for seven organophosphate substrates was simultaneously enhanced by up to five orders of magnitude, achieving absolute values of catalytic efficiencies up to 106 M?1 s?1. Structural and computational analyses identified the molecular basis for the enhanced OPH activity of the engineered PLL variants and demonstrated that OPH catalysis in PdPTE and the engineered PLL differ significantly in the mode of substrate binding. PMID:23837603

Meier, Monika M; Rajendran, Chitra; Malisi, Christoph; Fox, Nicholas G; Xu, Chengfu; Schlee, Sandra; Barondeau, David P; Höcker, Birte; Sterner, Reinhard; Raushel, Frank M

2013-01-01

231

Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles  

SciTech Connect

Bismuth ferrite (BFO) nanoparticles were synthesized by auto-ignition technique with and without adding ignition fuel such as citric acid. The presence of citric acid in the reaction mixture yielded highly-magnetic BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite. When this composite was annealed to 650 Degree-Sign C, a single phase BFO was formed with average crystallite size of 50 nm and showed weak ferromagnetic behavior. Conversely, the phase pure BFO prepared without adding citric acid exhibited antiferromagnetism because of its larger crystallite size of around 70 nm. The visible-light driven photocatalytic activity of both the pure BFO and BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite were examined by degrading methyl orange dye. The pure BFO showed a moderate photocatalytic activity; while BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite showed enhanced activity. This could be probably due to the optimal band gap ratio between BFO and {gamma}-Fe{sub 2}O{sub 3} phases reduced the recombination of electron-hole pairs which aided in the enhancement of photocatalytic activity.

Sakar, M.; Balakumar, S. [National Center for Nanoscience and Nanotechnology, University of Madras, Chennai - 600025 (India); Saravanan, P. [Advanced Magnetics Group, Defence Metallurgical Research Laboratory, Hyderabad - 500 058 (India); Jaisankar, S. N. [Polymer Lab, Central Leather Research Laboratory, Adyar, Chennai - 600020 (India)

2013-02-05

232

Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Bismuth ferrite (BFO) nanoparticles were synthesized by auto-ignition technique with and without adding ignition fuel such as citric acid. The presence of citric acid in the reaction mixture yielded highly-magnetic BFO/?-Fe2O3 nanocomposite. When this composite was annealed to 650°C, a single phase BFO was formed with average crystallite size of 50 nm and showed weak ferromagnetic behavior. Conversely, the phase pure BFO prepared without adding citric acid exhibited antiferromagnetism because of its larger crystallite size of around 70 nm. The visible-light driven photocatalytic activity of both the pure BFO and BFO/?-Fe2O3 nanocomposite were examined by degrading methyl orange dye. The pure BFO showed a moderate photocatalytic activity; while BFO/?-Fe2O3 nanocomposite showed enhanced activity. This could be probably due to the optimal band gap ratio between BFO and ?-Fe2O3 phases reduced the recombination of electron-hole pairs which aided in the enhancement of photocatalytic activity.

Sakar, M.; Balakumar, S.; Saravanan, P.; Jaisankar, S. N.

2013-02-01

233

AMPK-Dependent Metabolic Regulation by PPAR Agonists  

PubMed Central

Comprehensive studies support the notion that the peroxisome proliferator-activated receptors, (PPARs), PPAR?, PPAR?/?, and PPAR?, regulate cell growth, morphogenesis, differentiation, and homeostasis. Agonists of each PPAR subtype exert their effects similarly or distinctly in different tissues such as liver, muscle, fat, and vessels. It is noteworthy that PPAR? or PPAR? agonists have pharmacological effects by modulating the activity of AMPK, which is a key cellular energy sensor. However, the role of AMPK in the metabolic effects of PPAR agonists has not been thoroughly focused. Moreover, AMPK activation by PPAR agonists seems to be independent of the receptor activation. This intriguing action of PPAR agonists may account in part for the mechanistic basis of the therapeutics in the treatment of metabolic disease. In this paper, the effects of PPAR agonists on metabolic functions were summarized with particular reference to their AMPK activity regulation. PMID:20814441

Lee, Woo Hyung; Kim, Sang Geon

2010-01-01

234

The relationship between the agonist-induced activation and desensitization of the human tachykinin NK2 receptor expressed in Xenopus oocytes  

PubMed Central

Repeated applications of neurokinin?A (NKA) to oocytes injected with 25?ng wild-type hNK2 receptor cRNA caused complete attenuation of second and subsequent NKA-induced responses while analogous experiments using repeated applications of GR64349 and [Nle10]NKA(4–10) resulted in no such desensitization. This behaviour has been previously attributed to the ability of the different ligands to stabilize different active conformations of the receptor that have differing susceptibilities to receptor kinases (Nemeth & Chollet, 1995).However, for Xenopus oocytes injected (into the nucleus) with 10?ng wild-type hNK2 receptor cDNA, a single 100?nM concentration of any of the three ligands resulted in complete desensitization to further concentrations.On the other hand, none of the ligands caused any desensitization in oocytes injected with 0.25?ng wild-type hNK2 receptor cRNA, even at concentrations up to 10??M.The two N-terminally truncated analogues of neurokinin?A have a lower efficacy than NKA and it is likely that it is this property which causes the observed differences in desensitization, rather than the formation of alternative active states of the receptor.The peak calcium-dependent chloride current is not a reliable measure of maximal receptor stimulation and efficacy is better measured in this system by studying agonist-induced desensitization.The specific adenylyl cyclase inhibitor SQ22536 can enhance NKA and GR64349-mediated desensitization which suggests that agonist-induced desensitization involves the inhibition of adenylyl cyclase and the subsequent down-regulation of the cyclic AMP-dependent protein kinase, possibly by cross-talk to a second signalling pathway. PMID:9690859

Maudsley, S; Gent, J P; Findlay, J B C; Donnelly, D

1998-01-01

235

A Conserved Aspartic Acid Is Important for Agonist (VUAA1) and Odorant/Tuning Receptor-Dependent Activation of the Insect Odorant Co-Receptor (Orco)  

PubMed Central

Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco). An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca2+ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ?2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels. PMID:23894621

Kumar, Brijesh N.; Taylor, Robert W.; Pask, Gregory M.; Zwiebel, Laurence J.; Newcomb, Richard D.; Christie, David L.

2013-01-01

236

In vivo activity of the thyroid hormone receptor beta- and ?-selective agonists GC-24 and CO23 on rat liver, heart, and brain.  

PubMed

Thyroid hormone analogs with selective actions through specific thyroid hormone receptor (TR) subtypes are of great interest. They might offer the possibility of mimicking physiological actions of thyroid hormone with receptor subtype or tissue specificity with therapeutic aims. They are also pharmacological tools to dissect biochemical pathways mediated by specific receptor subtypes, in a complementary way to mouse genetic modifications. In this work, we studied the in vivo activity in developing rats of two thyroid hormone agonists, the TR?-selective GC-24 and the TR?-selective CO23. Our principal goal was to check whether these compounds were active in the rat brain. Analog activity was assessed by measuring the expression of thyroid hormone target genes in liver, heart, and brain, after administration to hypothyroid rats. GC-24 was very selective for TR? and lacked activity on the brain. On the other hand, CO23 was active in liver, heart, and brain on genes regulated by either TR? or TR?. This compound, previously shown to be TR?-selective in tadpoles, displayed no selectivity in the rat in vivo. PMID:21239431

Grijota-Martínez, Carmen; Samarut, Eric; Scanlan, Thomas S; Morte, Beatriz; Bernal, Juan

2011-03-01

237

The structural basis for agonist and partial agonist action on a ?(1)-adrenergic receptor.  

PubMed

?-adrenergic receptors (?ARs) are G-protein-coupled receptors (GPCRs) that activate intracellular G proteins upon binding catecholamine agonist ligands such as adrenaline and noradrenaline. Synthetic ligands have been developed that either activate or inhibit ?ARs for the treatment of asthma, hypertension or cardiac dysfunction. These ligands are classified as either full agonists, partial agonists or antagonists, depending on whether the cellular response is similar to that of the native ligand, reduced or inhibited, respectively. However, the structural basis for these different ligand efficacies is unknown. Here we present four crystal structures of the thermostabilized turkey (Meleagris gallopavo) ?(1)-adrenergic receptor (?(1)AR-m23) bound to the full agonists carmoterol and isoprenaline and the partial agonists salbutamol and dobutamine. In each case, agonist binding induces a 1?Å contraction of the catecholamine-binding pocket relative to the antagonist bound receptor. Full agonists can form hydrogen bonds with two conserved serine residues in transmembrane helix 5 (Ser(5.42) and Ser(5.46)), but partial agonists only interact with Ser(5.42) (superscripts refer to Ballesteros-Weinstein numbering). The structures provide an understanding of the pharmacological differences between different ligand classes, illuminating how GPCRs function and providing a solid foundation for the structure-based design of novel ligands with predictable efficacies. PMID:21228877

Warne, Tony; Moukhametzianov, Rouslan; Baker, Jillian G; Nehmé, Rony; Edwards, Patricia C; Leslie, Andrew G W; Schertler, Gebhard F X; Tate, Christopher G

2011-01-13

238

GnRH agonists.  

PubMed

The development of GnRH agonists has had a major impact on the practice of gynecology and reproductive endocrinology. The clinical usefulness of GnRH agonists will increase as modes of administration are improved and indications become better defined. GnRH agonists and, potentially, antagonists will provide a prompt, effective, and reversible method of suppressing ovarian function. GnRH agonists may soon become a treatment of choice for many of the noncontraceptive uses of oral contraceptives. Current indications for GnRH agonist administration are best divided into two groups: short-term (less than 6 months) and long-term (greater than 6 months) suppression. Short-term administration of GnRH agonist include most of the current usage of GnRH agonists. Short-term administration avoids most of the side effects of GnRH agonist and offers the most potential for development of GnRH antagonists. Short-term therapy has been shown to be particularly effective in the preoperative treatment of fibroids, suppression of ovarian function before ovulation induction, for short-term suppression of endometriosis, and for diagnostic purposes to determine whether a medical illness is related to ovarian function. Chronic administration of GnRH agonist has produced varying degrees of success. The treatment of precocious puberty is probably the perfect indication for GnRH agonist suppression. The disease is completely reversed with a remarkable absence of side effects. Long-term administration for metastatic breast or prostatic cancer has been shown to be as efficacious as other forms of gonadal suppression and the potential benefits of suppression outweigh the potential side effects of long-term suppression. The risk-benefit ratio must be carefully analyzed for the other indications for long-term suppression. Long-term suppression could be used for medical illnesses exacerbated by the menstrual cycle, painful symptoms related to endometriosis, contraception, and suppression of hyperandrogynism. Although initial studies show the agonist to be quite effective in treating all of these disorders, long-term suppression also may result in potential serious side effects related to hypoestrogenism including hot flashes and osteoporosis. Long-term administration of GnRH agonist may become feasible by lowering the dose and degree of suppression or by combining GnRH agonist with estrogen or progestin replacement, or both. PMID:2673600

Schriock, E D

1989-09-01

239

Desensitization of Human CRF2(a) Receptor Signaling Governed by Agonist Potency and ?Arrestin2 Recruitment  

PubMed Central

The primary goal was to determine agonist-specific regulation of CRF2(a) receptor function. Exposure of human retinoblastoma Y79 cells to selective (UCN2, UCN3 or stresscopins) and nonselective (UCN1 or sauvagine) agonists prominently desensitized CRF2(a) receptors in a rapid, concentration-dependent manner. A considerably slower rate and smaller magnitude of desensitization developed in response to the weak agonist CRF. CRF1 receptor desensitization stimulated by CRF, cortagine or stressin1-A had no effect on CRF2(a) receptor cyclic AMP signaling. Conversely, desensitization of CRF2(a) receptors by UCN2 or UCN3 did not cross-desensitize Gs-coupled CRF1 receptor signaling. In transfected HEK293 cells, activation of CRF2(a) receptors by UCN2, UCN3 or CRF resulted in receptor phosphorylation and internalization proportional to agonist potency. Neither protein kinase A nor casein kinases mediated CRF2(a) receptor phosphorylation or desensitization. Exposure of HEK293 or U2OS cells to UCN2 or UCN3 (100 nM) produced strong ?arrestin2 translocation and colocalization with membrane CRF2(a) receptors while CRF (1 µM) generated only weak ?arrestin2 recruitment. ?arrestin2 did not internalize with the receptor, however, indicating that transient CRF2(a) receptor-arrestin complexes dissociate at or near the cell membrane. Since deletion of the ?arrestin2 gene upregulated Gs-coupled CRF2(a) receptor signaling in MEF cells, a ?arrestin2 mechanism restrains Gs-coupled CRF2(a) receptor signaling activated by urocortins. We further conclude the rate and extent of homologous CRF2(a) receptor desensitization are governed by agonist-specific mechanisms affecting GRK phosphorylation, ?arrestin2 recruitment, and internalization thereby producing unique signal transduction profiles that differentially affect the stress response. PMID:23820308

Hauger, Richard L.; Olivares-Reyes, J. Alberto; Braun, Sandra; Hernandez-Aranda, Judith; Hudson, Christine C.; Gutknecht, Eric; Dautzenberg, Frank M.; Oakley, Robert H.

2013-01-01

240

Desensitization of human CRF2(a) receptor signaling governed by agonist potency and ?arrestin2 recruitment.  

PubMed

The primary goal was to determine agonist-specific regulation of CRF2(a) receptor function. Exposure of human retinoblastoma Y79 cells to selective (UCN2, UCN3 or stresscopins) and non-selective (UCN1 or sauvagine) agonists prominently desensitized CRF2(a) receptors in a rapid, concentration-dependent manner. A considerably slower rate and smaller magnitude of desensitization developed in response to the weak agonist CRF. CRF1 receptor desensitization stimulated by CRF, cortagine or stressin1-A had no effect on CRF2(a) receptor cyclic AMP signaling. Conversely, desensitization of CRF2(a) receptors by UCN2 or UCN3 did not cross-desensitize Gs-coupled CRF1 receptor signaling. In transfected HEK293 cells, activation of CRF2(a) receptors by UCN2, UCN3 or CRF resulted in receptor phosphorylation and internalization proportional to agonist potency. Neither protein kinase A nor casein kinases mediated CRF2(a) receptor phosphorylation or desensitization. Exposure of HEK293 or U2OS cells to UCN2 or UCN3 (100nM) produced strong ?arrestin2 translocation and colocalization with membrane CRF2(a) receptors while CRF (1?M) generated only weak ?arrestin2 recruitment. ?arrestin2 did not internalize with the receptor, however, indicating that transient CRF2(a) receptor-arrestin complexes dissociate at or near the cell membrane. Since deletion of the ?arrestin2 gene upregulated Gs-coupled CRF2(a) receptor signaling in MEF cells, a ?arrestin2 mechanism restrains Gs-coupled CRF2(a) receptor signaling activated by urocortins. We further conclude that the rate and extent of homologous CRF2(a) receptor desensitization are governed by agonist-specific mechanisms affecting GRK phosphorylation, ?arrestin2 recruitment, and internalization thereby producing unique signal transduction profiles that differentially affect the stress response. PMID:23820308

Hauger, Richard L; Olivares-Reyes, J Alberto; Braun, Sandra; Hernandez-Aranda, Judith; Hudson, Christine C; Gutknecht, Eric; Dautzenberg, Frank M; Oakley, Robert H

2013-09-10

241

Memory Enhancement Induced by Post-Training Intrabasolateral Amygdala Infusions of [beta]-Adrenergic or Muscarinic Agonists Requires Activation of Dopamine Receptors: Involvement of Right, but Not Left, Basolateral Amygdala  

ERIC Educational Resources Information Center

Previous findings indicate that the noradrenergic, dopaminergic, and cholinergic innervations of the basolateral amygdala (BLA) modulate memory consolidation. The current study investigated whether memory enhancement induced by post-training intra-BLA infusions of a [beta]-adrenergic or muscarinic cholinergic agonist requires concurrent activation

LaLumiere, Ryan T.; McGaugh, James L.

2005-01-01

242

Peroxisome Proliferator-Activated Receptor-? Agonist Treatment Increases Septation and Angiogenesis and Decreases Airway Hyperresponsiveness in a Model of Experimental Neonatal Chronic Lung Disease  

PubMed Central

Chronic lung disease (CLD) affects premature newborns requiring supplemental oxygen and results in impaired lung development and subsequent airway hyperreactivity. We hypothesized that the maintenance of peroxisome proliferator-activated receptor gamma (PPAR?) signaling is important for normal lung morphogenesis and treatment with PPAR? agonists could protect against CLD and airway hyperreactivity (AHR) following chronic hyperoxic exposure. This was tested in an established hyperoxic murine model of experimental CLD. Newborn mice and mothers were exposed to room air (RA) or moderate hyperoxia (70% oxygen) for 10 days and fed a standard diet or chow impregnated with the PPAR? agonist rosiglitazone (ROSI) for the duration of study. Following hyperoxic exposure (HE) animals were returned to RA until postnatal day (P) 13 or P41. The accumulation of ROSI in neonatal and adult tissue was confirmed by mass spectrometry. Analyses of body weight and lung histology were performed on P13 and P41 to localize and quantitate PPAR? expression, determine alveolar and microvessel density, proliferation and alpha-smooth muscle actin (?-SMA) levels as a measure of myofibroblast differentiation. Microarray analyses were conducted on P13 to examine transcriptional changes in whole lung. Pulmonary function and airway responsiveness were analyzed at P55. ROSI treatment during HE preserved septation and vascular density. Key array results revealed ontogeny groups differentially affected by hyperoxia including cell cycle, angiogenesis, matrix and muscle differentiation/contraction. These results were further confirmed by histological evaluation of myofibroblast and collagen accumulation. Late AHR to methacholine was present in mice following HE and attenuated with ROSI treatment. These findings suggest that rosiglitazone maintains downstream PPAR? effects and may be beneficial in the prevention of severe CLD with AHR. PMID:19484746

Takeda, K.; Okamoto, M.; De Langhe, S.; Dill, E.; Armstrong, M.; Reisdorf, N.; Irwin, D.; Koster, M.; Wilder, J.; Stenmark, K.R.; West, J.; Klemm, D.; Gelfand, E.W.; Nozik-Grayck, E.; Majka, S. M.

2010-01-01

243

Spinal cannabinoid receptor type 2 agonist reduces mechanical allodynia and induces mitogen-activated protein kinase phosphatases in a rat model of neuropathic pain  

PubMed Central

Peripheral nerve injury generally results in spinal neuronal and glial plastic changes associated with chronic behavioral hypersensitivity. Spinal mitogen-activated protein kinases (MAPKs), e.g., p38 or extracellular signal-regulated kinases (ERKs), are instrumental in the development of chronic allodynia in rodents, and new p38 inhibitors have shown potential in acute and neuropathic pain patients. We have previously shown that the cannabinoid type 2 receptor agonist JWH015 inhibits ERK activity by inducing MAPK phosphatase (MKP)-1 and MKP-3 (the major regulators of MAPKs) in vitro in microglial cells. Therefore, we decided to investigate the role of these phosphatases in the mechanisms of action of JWH015 in vivo using the rat L5 nerve transection model of neuropathic pain. We observed that peripheral nerve injury reduced spinal MKP-1/3 expression and activity and that intrathecal JWH015 reduced established L5 nerve-injury-induced allodynia, enhanced spinal MKP-1/3 expression and activity, and reduced the phosphorylated form of p38 and ERK-1/2. Triptolide, a pharmacological blocker of MKP-1 and MKP-3 expression, inhibited JWH015’s effects, suggesting that JWH015 exerts its antinociceptive effects by modulating MKP-1 and MKP-3. JWH015-induced antinociception and MKP-1 and MKP-3 expression were inhibited by the cannabinoid type 2 receptor antagonist AM630. Our data suggest that MKP-1 and MKP-3 are potential targets for novel analgesic drugs. PMID:22901764

Landry, Russell P.; Martinez, Elena; DeLeo, Joyce A.; Romero-Sandoval, E. Alfonso

2012-01-01

244

A pilot study of the effects of gonadotropin-releasing hormone agonist therapy on brain activation pattern in a man with pedophilia.  

PubMed

Gonadotropin-releasing hormone (GnRH) agonists, such as leuprorelin, are recommended in the patients with pedophilia at highest risk of offending. However, the cerebral mechanisms of the effects of these testosterone-decreasing drugs are poorly known. This study aimed to identify changes caused by leuprorelin in a pedophilic patient's brain responses to pictures representing children. Clinical, endocrine, and fMRI investigations were done of a man with pedophilia before leuprorelin therapy and 5 months into leuprorelin therapy. Patient was compared with an age-matched healthy control also assessed 5 months apart. Before therapy, pictures of boys elicited activation in the left calcarine fissure, left insula, anterior cingulate cortex, and left cerebellar vermis. Five months into therapy, all the above-mentioned activations had disappeared. No such activations and, consequently, no such decreases occurred in the healthy control. The results of this pilot study suggest that leuprorelin decreased activity in regions known to mediate the perceptual, motivational, and affective responses to visual sexual stimuli. PMID:21518701

Moulier, Virginie; Fonteille, Véronique; Pélégrini-Issac, Mélanie; Cordier, Bernard; Baron-Laforêt, Sophie; Boriasse, Emeline; Durand, Emmanuel; Stoléru, Serge

2012-02-01

245

GPR119 agonists: a promising approach for T2DM treatment? A SWOT analysis of GPR119.  

PubMed

Ever since its advent as a promising therapeutic target for type 2 diabetes mellitus (T2DM), G-protein-coupled receptor 119 (GPR119) has received much interest from the pharmaceutical industry. This interest peaked in June 2010, when Sanofi-Aventis agreed to pay Metabolex (Cymabay Therapeutics) US$375 million for MBX-2982, which was a representative orally active GPR119 agonist. However, Sanofi-Aventis opted to terminate the deal in May 2011 and another leading GPR119 agonist, GSK1292263, had a loss of efficacy during its clinical trial. In this review, I discuss the pros and cons of GPR119 through a strengths, weaknesses, opportunities, and threats (SWOT) analysis and propose development strategies for the eventual success of a GPR119 agonist development program. PMID:24060477

Kang, Sang-Uk

2013-12-01

246

Cell death is induced by ciglitazone, a peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) agonist, independently of PPAR{gamma} in human glioma cells  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Greater than 30 {mu}M ciglitazone induces cell death in glioma cells. Black-Right-Pointing-Pointer Cell death by ciglitazone is independent of PPAR{gamma} in glioma cells. Black-Right-Pointing-Pointer CGZ induces cell death by the loss of MMP via decreased Akt. -- Abstract: Peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) regulates multiple signaling pathways, and its agonists induce apoptosis in various cancer cells. However, their role in cell death is unclear. In this study, the relationship between ciglitazone (CGZ) and PPAR{gamma} in CGZ-induced cell death was examined. At concentrations of greater than 30 {mu}M, CGZ, a synthetic PPAR{gamma} agonist, activated caspase-3 and induced apoptosis in T98G cells. Treatment of T98G cells with less than 30 {mu}M CGZ effectively induced cell death after pretreatment with 30 {mu}M of the PPAR{gamma} antagonist GW9662, although GW9662 alone did not induce cell death. This cell death was also observed when cells were co-treated with CGZ and GW9662, but was not observed when cells were treated with CGZ prior to GW9662. In cells in which PPAR{gamma} was down-regulated cells by siRNA, lower concentrations of CGZ (<30 {mu}M) were sufficient to induce cell death, although higher concentrations of CGZ ( Greater-Than-Or-Slanted-Equal-To 30 {mu}M) were required to induce cell death in control T98G cells, indicating that CGZ effectively induces cell death in T98G cells independently of PPAR{gamma}. Treatment with GW9662 followed by CGZ resulted in a down-regulation of Akt activity and the loss of mitochondrial membrane potential (MMP), which was accompanied by a decrease in Bcl-2 expression and an increase in Bid cleavage. These data suggest that CGZ is capable of inducing apoptotic cell death independently of PPAR{gamma} in glioma cells, by down-regulating Akt activity and inducing MMP collapse.

Lee, Myoung Woo; Kim, Dae Seong; Kim, Hye Ryung; Kim, Hye Jin; Yang, Jin Mo; Ryu, Somi; Noh, Yoo Hun; Lee, Soo Hyun; Son, Meong Hi; Jung, Hye Lim; Yoo, Keon Hee [Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)] [Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Koo, Hong Hoe, E-mail: hhkoo@skku.edu [Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Sung, Ki Woong, E-mail: kwsped@skku.edu [Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2012-01-06

247

Inhibition of AMPA Receptors by Polyamine Toxins is Regulated by Agonist Efficacy and Stargazin.  

PubMed

The ?-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) are glutamate-gated cation channels mediating the majority of fast excitatory synaptic transmission in the central nervous system (CNS). Polyamine toxins derived from spiders and wasps are use- and voltage-dependent channel blockers of Ca(2+)-permeable AMPARs. Recent studies have suggested that AMPAR block by polyamine toxins is modulated by auxiliary subunits from the class of transmembrane AMPAR regulatory proteins (TARPs), which may have implications for their use as tool compounds in native systems. We have explored the effect of the TARP ?-2 (also known as stargazin) on the inhibitory potency of three structurally different polyamine toxins at Ca(2+)-permeable homomeric GluA1 AMPARs expressed in oocytes. We find that polyamine toxin IC50 is differentially affected by presence of stargazin depending on the efficacy of the agonists used to activate GluA1. Co-assembly of GluA1 receptors with stargazin increases the potency of the polyamine toxins when activated by the weak partial agonist kainate, but has no effect in presence of full-agonist L-glutamate (Glu) and partial agonist (RS)-willardiine. PMID:24557991

Poulsen, Mette H; Lucas, Simon; Strømgaard, Kristian; Kristensen, Anders S

2014-10-01

248

Comparison of the effects of the dopamine D2 agonist quinelorane on tuberoinfundibular dopaminergic neuronal activity in male and female rats.  

PubMed

The purpose of the present study was to examine the effects of quinelorane (LY163502), a potent and selective D2 dopaminergic (DA) receptor agonist, on the activity of tuberoinfundibular DA neurons in male and female rats as estimated by determining the concentration of the primary metabolite of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), in terminals of these neurons in the median eminence (ME). In males, quinelorane produced dose- and time-related increases in the concentration of DOPAC in the Me which was blocked by the D2 receptor antagonist raclopride. The activity of tuberoinfundibular neurons in female rats is higher than it is in males because circulating levels of prolactin tonically stimulate these neurons in the female. In female rats, quinelorane markedly lowered plasma concentrations of prolactin but failed to alter DOPAC concentrations in the ME. Pretreatment of female rats with prolactin antiserum induced hypoprolactinemia and reduced DOPAC concentrations in the ME; in these animals quinelorane increased ME DOPAC concentrations. These results indicate that by acting on D2 receptors quinelorane is able to stimulate tuberoinfundibular DA neurons in both male and female rats, but in female rats the ability of quinelorane to reduce circulating levels of prolactin indirectly reduces the activity of tuberoinfundibular DA neurons and thereby masks the stimulatory action of this drug on these neurons. PMID:7904532

Eaton, M J; Gopalan, C; Kim, E; Lookingland, K J; Moore, K E

1993-11-26

249

CCR5 Mutations Distinguish N-Terminal Modifications of RANTES (CCL5) with Agonist versus Antagonist Activity  

PubMed Central

CCR5 is the major HIV-1 entry coreceptor. RANTES/CCL5 analogs are more potent inhibitors of infection than native chemokines; one class activates and internalizes CCR5, one neither activates nor internalizes, and a third partially internalizes without activation. Here we show that mutations in CCR5 transmembrane domains differentially impact the activity of these three inhibitor classes, suggesting that the transmembrane region of CCR5, a key interaction site for inhibitors, is a sensitive molecular switch, modulating receptor activity. PMID:22787219

Choi, Won-Tak; Nedellec, Rebecca; Coetzer, Mia; Colin, Philippe; Lagane, Bernard; Offord, Robin E.; Hartley, Oliver

2012-01-01

250

Inhibition of MEK/ERK1/2 signalling alters endothelial nitric oxide synthase activity in an agonist-dependent manner.  

PubMed

eNOS (endothelial nitric oxide synthase) activity is post-translationally regulated in a complex fashion by acylation, protein-protein interactions, intracellular trafficking and phosphorylation, among others. Signalling pathways that regulate eNOS activity include phosphoinositide 3-kinase/Akt, cyclic nucleotide-dependent kinases [PKA (protein kinase A) and PKG], PKC, as well as ERKs (extracellular-signal-regulated kinases). The role of ERKs in eNOS activation remains controversial. In the present study, we have examined the role of ERK1/2 in eNOS activation in HUVEC-CS [transformed HUVEC (human umbilical-vein endothelial cells)] as well as a widely used model for eNOS study, transiently transfected COS-7 cells. U0126 pretreatment of HUVEC-CS potentiated ATP-stimulated eNOS activity, independent of changes in intracellular Ca2+ concentration ([Ca2+]i). In COS-7 cells transiently expressing ovine eNOS, U0126 potentiated A23187-stimulated eNOS activity, but inhibited ATP-stimulated activity. Compensatory changes in phosphorylation of five key eNOS residues did not account for changes in A23187-stimulated activity. However, in the case of ATP, altered phosphorylation and changes in [Ca2+]i may partially contribute to U0126 inhibition of activity. Finally, seven eNOS alanine mutants of putative ERK1/2 targets were generated and the effects of U0126 pretreatment on eNOS activity were gauged with A23187 and ATP treatment. T97A-eNOS was the only construct significantly different from wild-type after U0126 pretreatment and ATP stimulation of eNOS activation. In the present study, eNOS activity was either potentiated or inhibited in COS-7 cells, suggesting agonist dependence for MEK/ERK1/2 signalling [where MEK is MAPK (mitogen-activated protein kinase)/ERK kinase] to eNOS and a complex mechanism including [Ca2+]i, phosphorylation and, possibly, intracellular trafficking. PMID:16716148

Cale, Jacqueline M; Bird, Ian M

2006-09-01

251

Cannabinoid receptor type 2 agonist attenuates apoptosis by activation of phosphorylated CREB-Bcl-2 pathway after subarachnoid hemorrhage in rats.  

PubMed

Early brain injury (EBI) which comprises of vasogenic edema and apoptotic cell death is an important component of subarachnoid hemorrhage (SAH) pathophysiology. This study evaluated whether cannabinoid receptor type 2 (CB2R) agonist, JWH133, attenuates EBI after SAH and whether CB2R stimulation reduces pro-apoptotic caspase-3 via up-regulation of cAMP response element-binding protein (CREB)-Bcl-2 signaling pathway. Male Sprague-Dawley rats (n=123) were subjected to SAH by endovascular perforation. Rats received vehicle or JWH133 at 1h after SAH. Neurological deficits and brain water content were evaluated at 24h after SAH. Western blot was performed to quantify phosphorylated CREB (pCREB), Bcl-2, and cleaved caspase-3 levels. Neuronal cell death was evaluated with terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling staining. Additionally, CREB siRNA was administered to manipulate the proposed pathway. JWH133 (1.0mg/kg) improved neurological deficits and reduced brain water content in left hemisphere 24h after SAH. JWH133 significantly increased activated CREB (pCREB) and Bcl-2 levels and significantly decreased cleaved caspase-3 levels in left hemisphere 24h after SAH. CREB siRNA reversed the effects of treatment. TUNEL positive neurons in the cortex were reduced with JWH133 treatment. Thus, CB2R stimulation attenuated EBI after SAH possibly through activation of pCREB-Bcl-2 pathway. PMID:25058046

Fujii, Mutsumi; Sherchan, Prativa; Soejima, Yoshiteru; Hasegawa, Yu; Flores, Jerry; Doycheva, Desislava; Zhang, John H

2014-11-01

252

Environmental, seasonal, and social modulations of basal activity in a weakly electric fish.  

PubMed

The electric organ discharge (EOD) of weakly electric fish encodes information about species, sex, behavioral, and physiological states throughout the lifetime. Its central command is crucial for sensory-motor coordination, and is therefore the target of plastic mechanisms that adapt fish to environmental and social challenges. The EOD waveform of Brachyhypopomus pinnicaudatus is modulated by environmental factors and the neuroendocrine system. In this study we investigate the effects of water temperature and day-night cycle upon EOD rate in this species during the breeding and non-breeding seasons. During the non-breeding season, EOD rate is a linear function of water temperature and exhibits counterclockwise hysteresis. During breeding, a thermal resistance strategy prevents the decrease of EOD rate to cooling. A nocturnal increase of EOD basal rate independent of water temperature and locomotor activity was demonstrated in isolated non-breeding adults and in male-female dyads all year round. An additional increase of nocturnal EOD rate, probably acting as a social courtship signal, was found in breeding dyads. This additional increase of nocturnal EOD rate could not be fully explained by gonadal maturation and was modulated by social stimuli. This study provides novel data on the complex interactions between environment, reproductive cycle, social behavior, and electromotor output in an advantageous model of the vertebrate central nervous system. PMID:17178133

Silva, Ana; Perrone, Rossana; Macadar, Omar

2007-02-28

253

The peroxisome proliferator-activated receptor ?/? (PPAR?/?) agonist GW501516 prevents TNF-?-induced NF-?B activation in human HaCaT cells by reducing p65 acetylation through AMPK and SIRT1.  

PubMed

Nuclear factor (NF)-?B is a ubiquitously expressed transcription factor controlling the expression of numerous genes involved in inflammation. The aim of this study was to evaluate whether activation of the peroxisome proliferator-activated receptor (PPAR) ?/? prevented TNF-?-induced NF-?B activation in human HaCaT keratinocytes and, if so, to determine the mechanism involved. The PPAR?/? agonist GW501516 inhibited the increase caused by TNF-? in the mRNA levels of the NF-?B target genes interleukin 8 (IL-8), TNF-? and thymic stromal lymphopoietin (TSLP). Likewise, GW501516 prevented the increase in NF-?B DNA-binding activity observed in cells exposed to TNF-?. The reduction in NF-?B activity following GW501516 treatment in cells stimulated with TNF-? did not involve either increased I?B? protein levels or a reduction in the translocation of the p65 subunit of NF-?B. In contrast, GW501516 treatment decreased TNF-?-induced p65 acetylation. Acetylation of p65 is mainly regulated by p300, a transcriptional co-activator that binds to and acetylates p65. Of note, AMP kinase (AMPK) activation phosphorylates p300 and reduces its binding to p65. GW501516 increased AMPK phosphorylation and the subsequent p300 phosphorylation, leading to a marked reduction in the association between p65 and this transcriptional co-activator. In addition, treatment with the PPAR?/? agonist increased SIRT1 protein levels. Finally, the reduction in IL-8 mRNA levels following GW501516 treatment in TNF-?-stimulated cells was abolished in the presence of the PPAR?/? antagonist GSK0660, the AMPK inhibitor compound C and the SIRT1 inhibitor sirtinol, indicating that the effects of GW501516 on NF-?B activity were dependent on PPAR?/?, AMPK and SIRT1, respectively. PMID:21146504

Barroso, Emma; Eyre, Elena; Palomer, Xavier; Vázquez-Carrera, Manuel

2011-02-15

254

Olanzapine-Activated AMPK Signaling in the Dorsal Vagal Complex Is Attenuated by Histamine H1 Receptor Agonist in Female Rats.  

PubMed

Weight gain and its related metabolic disorders are major side effects associated with second generation antipsychotic drug treatment. The dorsal vagal complex (DVC) and AMP-activated protein kinase (AMPK) are implicated in the regulation of food intake and body weight. Blocking the histamine H1 receptor contributes to antipsychotic-induced weight gain. The present study investigated the time-dependent effect of olanzapine treatment (8, 16, and 36 d) on DVC AMPK signaling in olanzapine-induced weight gain and whether these changes are associated with olanzapine-induced H1 receptor antagonism. During the 8-day olanzapine treatment, the rats were hyperphagic and rapidly gained weight. The phosphorylation of AMPK (pAMPK) (activated AMPK) as well as its directly downstream phospho-acetyl-coenzyme A carboxylase was significantly increased. The pAMPK/AMPK ratio, an indicator of AMPK activity, was significantly positively correlated with feeding efficiency and weight gain. As treatment was prolonged (16 and 36 d of olanzapine treatment), the rats were no longer hyperphagic, and there were no longer any changes in DVC AMPK signaling. Although the DVC H1 receptor protein expression was not significantly altered by olanzapine, the pAMPK expression was significantly positively correlated with the H1 receptor level after the 8-, 16-, and 36-day olanzapine treatments. Moreover, we showed that an H1 receptor agonist, 2-(3-trifluoromethylphenyl) histamine, significantly inhibited the olanzapine-induced hyperphagia and DVC AMPK activation in a dose-dependent manner. These results suggest a time-dependent role of DVC AMPK in olanzapine-induced obesity. Thus, olanzapine-induced DVC AMPK activation may be at least partially related to olanzapine's antagonistic effect on the H1 receptor. PMID:25264935

He, Meng; Zhang, Qingsheng; Deng, Chao; Wang, Hongqin; Huang, Xu-Feng

2014-12-01

255

Peroxisome proliferator-activated receptor {alpha} agonists modulate Th1 and Th2 chemokine secretion in normal thyrocytes and Graves' disease  

SciTech Connect

Until now, no data are present about the effect of peroxisome proliferator-activated receptor (PPAR){alpha} activation on the prototype Th1 [chemokine (C-X-C motif) ligand (CXCL)10] (CXCL10) and Th2 [chemokine (C-C motif) ligand 2] (CCL2) chemokines secretion in thyroid cells. The role of PPAR{alpha} and PPAR{gamma} activation on CXCL10 and CCL2 secretion was tested in Graves' disease (GD) and control primary thyrocytes stimulated with interferon (IFN){gamma} and tumor necrosis factor (TNF){alpha}. IFN{gamma} stimulated both CXCL10 and CCL2 secretion in primary GD and control thyrocytes. TNF{alpha} alone stimulated CCL2 secretion, while had no effect on CXCL10. The combination of IFN{gamma} and TNF{alpha} had a synergistic effect both on CXCL10 and CCL2 chemokines in GD thyrocytes at levels comparable to those of controls. PPAR{alpha} activators inhibited the secretion of both chemokines (stimulated with IFN{gamma} and TNF{alpha}) at a level higher (for CXCL10, about 60-72%) than PPAR{gamma} agonists (about 25-35%), which were confirmed to inhibit CXCL10, but not CCL2. Our data show that CCL2 is modulated by IFN{gamma} and TNF{alpha} in GD and normal thyrocytes. Furthermore we first show that PPAR{alpha} activators inhibit the secretion of CXCL10 and CCL2 in thyrocytes, suggesting that PPAR{alpha} may be involved in the modulation of the immune response in the thyroid.

Antonelli, Alessandro, E-mail: a.antonelli@med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy)] [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Ferrari, Silvia Martina, E-mail: sm.ferrari@int.med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Frascerra, Silvia, E-mail: lafrasce@gmail.com [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy)] [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Corrado, Alda, E-mail: dala_res@hotmail.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy)] [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Pupilli, Cinzia, E-mail: c.pupilli@dfc.unifi.it [Endocrinology Unit, Azienda Ospedaliera Careggi and University of Florence, Viale Morgagni 85, I-50134, Florence (Italy)] [Endocrinology Unit, Azienda Ospedaliera Careggi and University of Florence, Viale Morgagni 85, I-50134, Florence (Italy); Bernini, Giampaolo, E-mail: g.bernini@int.med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy)] [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Benvenga, Salvatore, E-mail: s.benvenga@me.nettuno.it [Department of Clinical and Experimental Medicine, Section of Endocrinology, University of Messina, Piazza Pugliatti 1, I-98122, Messina (Italy)] [Department of Clinical and Experimental Medicine, Section of Endocrinology, University of Messina, Piazza Pugliatti 1, I-98122, Messina (Italy); Ferrannini, Ele, E-mail: eferrannini@med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy)] [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Fallahi, Poupak, E-mail: poupak@int.med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy)] [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy)

2011-07-01

256

3-Dimensional Scene Perception during Active Electrolocation in a Weakly Electric Pulse Fish  

PubMed Central

Weakly electric fish use active electrolocation for object detection and orientation in their environment even in complete darkness. The African mormyrid Gnathonemus petersii can detect object parameters, such as material, size, shape, and distance. Here, we tested whether individuals of this species can learn to identify 3-dimensional objects independently of the training conditions and independently of the object's position in space (rotation-invariance; size-constancy). Individual G. petersii were trained in a two-alternative forced-choice procedure to electrically discriminate between a 3-dimensional object (S+) and several alternative objects (S?). Fish were then tested whether they could identify the S+ among novel objects and whether single components of S+ were sufficient for recognition. Size-constancy was investigated by presenting the S+ together with a larger version at different distances. Rotation-invariance was tested by rotating S+ and/or S? in 3D. Our results show that electrolocating G. petersii could (1) recognize an object independently of the S? used during training. When only single components of a complex S+ were offered, recognition of S+ was more or less affected depending on which part was used. (2) Object-size was detected independently of object distance, i.e. fish showed size-constancy. (3) The majority of the fishes tested recognized their S+ even if it was rotated in space, i.e. these fishes showed rotation-invariance. (4) Object recognition was restricted to the near field around the fish and failed when objects were moved more than about 4?cm away from the animals. Our results indicate that even in complete darkness our G. petersii were capable of complex 3-dimensional scene perception using active electrolocation. PMID:20577635

von der Emde, Gerhard; Behr, Katharina; Bouton, Béatrice; Engelmann, Jacob; Fetz, Steffen; Folde, Caroline

2010-01-01

257

Mechanism of antiplatelet action of hypolipidemic, antidiabetic and antihypertensive drugs by PPAR activation: PPAR agonists: new antiplatelet agents.  

PubMed

Given the prevalence of cardiovascular disease in patients with cardiovascular risk factors (i.e., hypertension, diabetes, smoking and obesity) and that platelet activation plays an important pathogenic role in cardiovascular diseases, it is very important to identify the drugs that have multiple targets. In this sense, the present article describes the mechanism of antiplatelet action of hypolipidemic (statins and fibrates), antidiabetic (thiazolidinediones) and antihypertensive (nifedipine) drugs via peroxisome proliferator-activated receptor (PPAR) activation. The mechanism of antiplatelet action of the drugs is by direct activation of PPARs with the inhibition of cyclooxygenase-1, protein kinase C-alpha, calcium mobilization, thromboxane A2, sCD40L, platelet microparticles and cAMP-phosphodiesterase, and the stimulation of proteins kinase G and A. Thus, these observations highlight PPARs as a novel therapeutic target for the treatment and prevention of cardiovascular diseases. PMID:24874279

Fuentes, Eduardo; Palomo, Iván

2014-09-01

258

Ombuin-3-O-?-D-glucopyranoside from Gynostemma pentaphyllum is a dual agonistic ligand of peroxisome proliferator-activated receptors ? and ?/?  

SciTech Connect

Highlights: ? Ombuin-3-O-?-D-glucopyranoside is a dual ligand for PPAR? and ?/?. ? Ombuin-3-O-?-D-glucopyranoside reduces cellular lipid levels in multiple cell types. ? Cells stimulated with ombuine up-regulated target genes in cholesterol efflux. ? Cells stimulated with ombuine regulated target fatty acid ?-oxidation and synthesis. ? Ombuin-3-O-?-D-glucopyranoside could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: We demonstrated that ombuin-3-O-?-D-glucopyranoside (ombuine), a flavonoid from Gynostemma pentaphyllum, is a dual agonist for peroxisome proliferator-activated receptors (PPARs) ? and ?/?. Using surface plasmon resonance (SPR), time-resolved fluorescence resonance energy transfer (FRET) analyses, and reporter gene assays, we showed that ombuine bound directly to PPAR? and ?/? but not to PPAR? or liver X receptors (LXRs). Cultured HepG2 hepatocytes stimulated with ombuine significantly reduced intracellular concentrations of triglyceride and cholesterol and downregulated the expression of lipogenic genes, including sterol regulatory element binding protein-1c (SREBP1c) and stearoyl-CoA desaturase-1 (SCD-1), with activation of PPAR? and ?/?. Activation of LXRs by ombuine was confirmed by reporter gene assays, however, SPR and cell-based FRET assays showed no direct binding of ombuine to either of the LXRs suggesting LXR activation by ombuine may be operated via PPAR? stimulation. Ombuine-stimulated macrophages showed significantly induced transcription of ATP binding cassette cholesterol transporter A1 (ABCA1) and G1 (ABCG1), the key genes in reverse cholesterol transport, which led to reduced cellular cholesterol concentrations. These results suggest that ombuine is a dual PPAR ligand for PPAR? and ?/? with the ability to decrease lipid concentrations by reducing lipogenic gene expression in hepatocytes and inducing genes involved in cholesterol efflux in macrophages.

Malek, Mastura Abd; Hoang, Minh-Hien; Jia, Yaoyao; Lee, Ji Hae; Jun, Hee Jin [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of) [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Dong-Ho [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of)] [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Hak Ju [Division of Green Business Management, Department of Forest Resources Utilization, Korean Forest Research Institute, Seoul 130-712 (Korea, Republic of)] [Division of Green Business Management, Department of Forest Resources Utilization, Korean Forest Research Institute, Seoul 130-712 (Korea, Republic of); Lee, Chul; Lee, Myung Koo [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of)] [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Hwang, Bang Yeon, E-mail: byhwang@chungbuk.ac.kr [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Lee, Sung-Joon, E-mail: junelee@korea.ac.kr [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of) [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of)

2013-01-25

259

Peroxisome proliferator-activated receptor-gamma agonist rosiglitazone reverses the adverse effects of diet-induced obesity on oocyte quality.  

PubMed

Obesity and its physiological consequences are increasingly prevalent among women of reproductive age and are associated with infertility. To investigate, female mice were fed a high-fat diet until the onset of insulin resistance, followed by assessments of ovarian gene expression, ovulation, fertilization, and oocyte developmental competence. We report defects to ovarian function associated with diet-induced obesity (DIO) that result in poor oocyte quality, subsequently reduced blastocyst survival rates, and abnormal embryonic cellular differentiation. To identify critical cellular mediators of ovarian responses to obesity induced insulin resistance, DIO females were treated for 4 d before mating with an insulin-sensitizing pharmaceutical: glucose and lipid-lowering AMP kinase activator, 5-aminoimidazole 4-carboxamide-riboside, 30 mg/kg.d; sodium salicylate, IkappaK inhibitor that reverses insulin resistance, 50 mg/kg.d; or peroxisome proliferator activated receptor-gamma agonist rosiglitazone, 10 mg/kg.d. 5-aminoimidazole 4-carboxamide-riboside or sodium salicylate treatment did not have significant effects on the reproductive parameters examined. However, embryonic development to the blastocyst stage was significantly improved when DIO mice were treated with rosiglitazone, effectively repairing development rates. Rosiglitazone also normalized DIO-associated abnormal blastomere allocation to the inner cell mass. Such improvements to oocyte quality were coupled with weight loss, improved glucose metabolism, and changes in ovarian mRNA expression of peroxisome proliferator activated receptor-regulated genes, Cd36, Scarb1, and Fabp4 cholesterol transporters. These studies demonstrate that peri-conception treatment with select insulin-sensitizing pharmaceuticals can directly influence ovarian functions and ultimately exert positive effects on oocyte developmental competence. Improved blastocyst quality in obese females treated with rosiglitazone before mating indicates that peroxisome proliferator activated receptor-gamma is a key target for metabolic regulation of ovarian function and oocyte quality. PMID:18276752

Minge, Cadence E; Bennett, Brenton D; Norman, Robert J; Robker, Rebecca L

2008-05-01

260

Normal testicular function without detectable follicle-stimulating hormone. A novel mutation in the follicle-stimulating hormone receptor gene leading to apparent constitutive activity and impaired agonist-induced desensitization and internalization.  

PubMed

Activating mutations in the follicle-stimulating hormone (FSH) receptor (FSHR) gene are rarely detected due to the absence of a clearly defined phenotype, particularly in men. We here report the biochemical features of a novel mutation in the first extracellular loop of the FSHR. The mutation (N431I) was detected in an asymptomatic man exhibiting normal spermatogenesis, suppressed serum FSH, and normal or elevated levels of biochemical markers of FSH action. Employing different experimental strategies on HEK-293 cells transiently expressing the N431I FSHR mutant, we found that the mutation led to decreased cell surface plasma membrane expression of the receptor protein, but conferred a low level of constitutive activity associated with markedly altered agonist-stimulated desensitization and internalization. These latter features may contribute and/or amplify the persistent activation of the receptor in both absence and presence of agonist and provide new insights into opportunities for adjuvant therapies based on disruption of these processes. PMID:22954680

Casas-González, Patricia; Scaglia, Hugo E; Pérez-Solís, Marco A; Durand, Guillaume; Scaglia, Javier; Zariñán, Teresa; Dias, James A; Reiter, Eric; Ulloa-Aguirre, Alfredo

2012-11-25

261

Suppression of Noxious Stimulus-Evoked Activity in the Ventral Posterolateral Nucleus of the Thalamus by a Cannabinoid Agonist: Correlation between Electrophysiological and Antinociceptive Effects  

Microsoft Academic Search

The CNS contains a putative cannabinergic neurotransmitter and an abundance of G-protein-coupled cannabinoid recep- tors. However, little is known about the function of this novel neurochemical system. Cannabinoid agonists produce antino- ciception in behavioral tests, suggesting the possibility that this system serves in part to modulate pain sensitivity. To explore this possibility, the effects of the cannabinoid agonist WIN 55,212-2

William J. Martin; Andrea G. Hohmann; J. Michael Walker

262

Peroxisome proliferator-activated receptor {alpha} agonist-induced down-regulation of hepatic glucocorticoid receptor expression in SD rats  

SciTech Connect

It was reported that glucocorticoid production was inhibited by fenofibrate through suppression of type-1 11{beta}-hydroxysteroid dehydrogenase gene expression in liver. The inhibition might be a negative-feedback regulation of glucocorticoid receptor (GR) activity by peroxisome proliferator-activated receptor alpha (PPAR{alpha}), which is quickly induced by glucocorticoid in the liver. However, it is not clear if GR expression is changed by fenofibrate-induced PPAR{alpha} activation. In this study, we tested this possibility in the liver of Sprague-Dawley rats. GR expression was reduced by fenofibrate in a time- and does-dependent manner. The inhibition was observed in liver, but not in fat and muscle. The corticosterone level in the blood was increased significantly by fenofibrate. These effects of fenofibrate were abolished by PPAR{alpha} inhibitor MK886, suggesting that fenofibrate activated through PPAR{alpha}. In conclusion, inhibition of GR expression may represent a new molecular mechanism for the negative feedback regulation of GR activity by PPAR{alpha}.

Chen Xiang; Li Ming; Sun Weiping; Bi Yan; Cai Mengyin; Liang Hua; Yu Qiuqiong; He Xiaoying [Department of Endocrinology, Third Affiliated Hospital of Sun Yat-Sen University, 600 Tianhe Road, Guangzhou, Guang Dong 510630 (China); Weng Jianping [Department of Endocrinology, Third Affiliated Hospital of Sun Yat-Sen University, 600 Tianhe Road, Guangzhou, Guang Dong 510630 (China)], E-mail: wjianp@mail.sysu.edu.cn

2008-04-18

263

Rosiglitazone, a Peroxisome Proliferator-Activated Receptor-? Agonist, Restores Alveolar and Pulmonary Vascular Development in a Rat Model of Bronchopulmonary Dysplasia  

PubMed Central

Purpose We tested whether rosiglitazone (RGZ), a peroxisome proliferator-activated receptor-? agonist, can restore alveolar development and vascular growth in a rat model of bronchopulmonary dysplasia (BPD). Materials and Methods A rat model of BPD was induced through intra-amniotic delivery of lipopolysaccharide (LPS) and postnatal hyperoxia (80% for 7 days). RGZ (3 mg/kg/d, i.p.) or vehicle was given daily to rat pups for 14 days. This model included four experimental groups: No BPD+vehicle (V), No BPD+RGZ, BPD+V, and BPD+RGZ. On D14, alveolarization, lung vascular density, and right ventricular hypertrophy (RVH) were evaluated. Results Morphometric analysis revealed that the BPD+RGZ group had significantly smaller and more complex airspaces and larger alveolar surface area than the BPD+V group. The BPD+RGZ group had significantly greater pulmonary vascular density than the BPD+V group. Western blot analysis revealed that significantly decreased levels of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 by the combined exposure to intra-amniotic LPS and postnatal hyperoxia were restored by the RGZ treatment. RVH was significantly lesser in the BPD+RGZ group than in the BPD+V group. Conclusion These results suggest that RGZ can restore alveolar and pulmonary vascular development and lessen pulmonary hypertension in a rat model of BPD. PMID:24339293

Lee, Hyun Ju; Lee, Youn Jin; Lee, Jin-A; Kim, Ee-Kyung; Kim, Han-Suk; Kim, Beyong Il; Choi, Jung-Hwan

2014-01-01

264

Administration of the peroxisomal proliferator-activated receptor {gamma} agonist pioglitazone during fractionated brain irradiation prevents radiation-induced cognitive impairment  

SciTech Connect

Purpose: We hypothesized that administration of the anti-inflammatory peroxisomal proliferator-activated receptor {gamma} (PPAR{gamma}) agonist pioglitazone (Pio) to adult male rats would inhibit radiation-induced cognitive impairment. Methods and Materials: Young adult male F344 rats received one of the following: (1) fractionated whole brain irradiation (WBI); 40 or 45 Gy {gamma}-rays in 4 or 4.5 weeks, respectively, two fractions per week and normal diet; (2) sham-irradiation and normal diet; (3) WBI plus Pio (120 ppm) before, during, and for 4 or 54 weeks postirradiation; (4) sham-irradiation plus Pio; or (5) WBI plus Pio starting 24h after completion of WBI. Results: Administration of Pio before, during, and for 4 or 54 weeks after WBI prevented Radiation-induced cognitive impairment. Administration of Pio for 54 weeks starting after completion of fractionated WBI substantially but not significantly reduced Radiation-induced cognitive impairment. Conclusions: These findings offer the promise of improving the quality of life and increasing the therapeutic window for brain tumor patients.

Zhao Weiling [Department of Radiation Oncology, Brain Tumor Center of Excellence, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Payne, Valerie [Department of Radiation Oncology, Brain Tumor Center of Excellence, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Tommasi, Ellen [Hypertension and Vascular Disease Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Diz, Debra I. [Hypertension and Vascular Disease Center, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Hsu, F.-C. [Department of Biostatistical Sciences, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Robbins, Mike E. [Department of Radiation Oncology, Brain Tumor Center of Excellence, Wake Forest University School of Medicine, Winston-Salem, NC (United States)]. E-mail: mrobbins@wfubmc.edu

2007-01-01

265

Inhibition of rotavirus ECwt infection in ICR suckling mice by N-acetylcysteine, peroxisome proliferator-activated receptor gamma agonists and cyclooxygenase-2 inhibitors  

PubMed Central

Live attenuated vaccines have recently been introduced for preventing rotavirus disease in children. However, alternative strategies for prevention and treatment of rotavirus infection are needed mainly in developing countries where low vaccine coverage occurs. In the present work, N-acetylcysteine (NAC), ascorbic acid (AA), some nonsteroidal anti-inflammatory drugs (NSAIDs) and peroxisome proliferator-activated receptor gamma (PPAR?) agonists were tested for their ability to interfere with rotavirus ECwt infectivity as detected by the percentage of viral antigen-positive cells of small intestinal villi isolated from ECwt-infected ICR mice. Administration of 6 mg NAC/kg every 8 h for three days following the first diarrhoeal episode reduced viral infectivity by about 90%. Administration of AA, ibuprofen, diclofenac, pioglitazone or rosiglitazone decreased viral infectivity by about 55%, 90%, 35%, 32% and 25%, respectively. ECwt infection of mice increased expression of cyclooxygenase-2, ERp57, Hsc70, NF-?B, Hsp70, protein disulphide isomerase (PDI) and PPAR? in intestinal villus cells. NAC treatment of ECwt-infected mice reduced Hsc70 and PDI expression to levels similar to those observed in villi from uninfected control mice. The present results suggest that the drugs tested in the present work could be assayed in preventing or treating rotaviral diarrhoea in children and young animals. PMID:24037197

Guerrero, Carlos Arturo; Pardo, Paula; Rodriguez, Victor; Guerrero, Rafael; Acosta, Orlando

2013-01-01

266

Increased agonist affinity at the mu-opioid receptor induced by prolonged agonist exposure  

PubMed Central

Prolonged exposure to high-efficacy agonists results in desensitization of the mu opioid receptor (MOR). Desensitized receptors are thought to be unable to couple to G-proteins, preventing downstream signaling, however the changes to the receptor itself are not well characterized. In the current study, confocal imaging was used to determine whether desensitizing conditions cause a change in agonist-receptor interactions. Using rapid solution exchange, the binding kinetics of fluorescently labeled opioid agonist, dermorphin Alexa594 (derm A594), to MORs was measured in live cells. The affinity of derm A594 binding increased following prolonged treatment of cells with multiple agonists that are known to cause receptor desensitization. In contrast, binding of a fluorescent antagonist, naltrexamine Alexa 594, was unaffected by similar agonist pre-treatment. The increased affinity of derm A594 for the receptor was long-lived and partially reversed after a 45 min wash. Treatment of the cells with pertussis toxin did not alter the increase in affinity of the derm A594 for MOR. Likewise the affinity of derm A594 for MORs expressed in mouse embryonic fibroblasts derived from arrestin 1 and 2 knockout animals increased following treatment of the cells with the desensitization protocol. Thus, opioid receptors were “imprinted” with a memory of prior agonist exposure that was independent of G-protein activation or arrestin binding that altered subsequent agonist-receptor interactions. The increased affinity suggests that acute desensitization results in a long lasting but reversible conformational change in the receptor. PMID:23447620

Birdsong, William T.; Arttamangkul, Seksiri; Clark, Mary J.; Cheng, Kejun; Rice, Kenner C.; Traynor, John R.; Williams, John T.

2013-01-01

267

Synthesis of isosteric selenium analog of the PPARbeta/delta agonist GW501516 and comparison of biological activity.  

PubMed

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors and members of the nuclear hormone receptor superfamily. Herein, we describe an efficient synthesis of a novel isosteric selenium analog of the highly specific PPARbeta/delta ligand 2-methyl-4-((4-methyl-2-(4-trifluoromethylphenyl)-1,3-thiazol-5-yl)-methylsulfanyl)phenoxy-acetic acid (GW501516; 1). The study examined the efficiency of the novel selenium analog 2-methyl-4-((4-methyl-2-(4-trifluoromethylphenyl)-1,3-selenazol-5-yl)-methylsulfanyl)phenoxy-acetic acid (2) to activate PPARbeta/delta and the effect of ligand activation of PPARbeta/delta on cell proliferation and target gene expression in human HaCaT keratinocytes. The results showed that similar to GW501516, the Se-analog 2 increased expression of the known PPARbeta/delta target gene angiopoietin-like protein 4 (ANGPTL4); the compound 2 was comparable in efficacy as compared to GW501516. Consistent with a large body of evidence, the Se-analog inhibited cell proliferation in HaCaT keratinocytes similar to that observed with GW501516. In summary, the novel Se-analog 2 has been developed as a potent PPARbeta/delta ligand that may possess additional anti-cancer properties of selenium. PMID:20542425

Sharma, Arun K; Sk, Ugir Hossain; He, Pengfei; Peters, Jeffrey M; Amin, Shantu

2010-07-15

268

The oxidative stress mediator 4-hydroxynonenal is an intracellular agonist of the nuclear receptor peroxisome proliferator-activated receptor-?\\/? (PPAR?\\/?)  

Microsoft Academic Search

Liver insufficiency and damage are major causes of death and disease worldwide and may result from exposure to environmental toxicants, specific combinations or dosages of pharmaceuticals, and microbial metabolites. The generation of reactive intermediates, in particular 4-hydroxynonenal (4-HNE), is a common event in liver damage caused by a variety of hepatotoxic drugs and solvents. The peroxisome proliferator-activated receptors (PPARs) are

Jeffrey D. Coleman; K. Sandeep Prabhu; Jerry T. Thompson; P. Sreenivasula Reddy; Jeffrey M. Peters; Blake R. Peterson; C. Channa Reddy; John P. Vanden Heuvel

2007-01-01

269

The dectin 1 agonist curdlan regulates osteoclastogenesis by inhibiting nuclear factor of activated T cells cytoplasmic 1 (NFATc1) through Syk kinase.  

PubMed

Several immune system cell surface receptors are reported to be associated with osteoclastogenesis. Dectin 1, a lectin receptor for ?-glucan, is found predominantly on cells of the myeloid lineage. In this study, we examined the effect of the dectin 1 agonist curdlan on osteoclastogenesis. In mouse bone marrow cells and dectin 1-overexpressing RAW 264.7 cells (d-RAWs), curdlan suppressed receptor activator of NF-?B ligand (RANKL)-induced osteoclast differentiation, bone resorption, and actin ring formation in a dose-dependent manner. This was achieved within non-growth inhibitory concentrations at the early stage. Conversely, curdlan had no effect on macrophage colony-stimulating factor-induced differentiation. Furthermore, curdlan inhibited RANKL-induced nuclear factor of activated T cell cytoplasmic 1 (NFATc1) expression, thereby decreasing osteoclastogenesis-related marker gene expression, including tartrate-resistant acid phosphatase, osteoclast stimulatory transmembrane protein, cathepsin K, and matrix metallopeptidase 9. Curdlan inhibited RANKL-induced c-fos expression, followed by suppression of NFATc1 autoamplification, without significantly affecting the NF-?B signaling pathway. We also observed that curdlan treatment decreased Syk protein in d-RAWs. Inhibition of the dectin 1-Syk kinase pathway by Syk-specific siRNA or chemical inhibitors suppressed osteoclast formation and NFATc1 expression stimulated by RANKL. In conclusion, our results demonstrate that curdlan potentially inhibits osteoclast differentiation, especially NFATc1 expression, and that Syk kinase plays a crucial role in the transcriptional pathways. This suggests that the activation of dectin 1-Syk kinase interaction critically regulates the genes required for osteoclastogenesis. PMID:24821724

Yamasaki, Toru; Ariyoshi, Wataru; Okinaga, Toshinori; Adachi, Yoshiyuki; Hosokawa, Ryuji; Mochizuki, Shinichi; Sakurai, Kazuo; Nishihara, Tatsuji

2014-07-01

270

Alterations in the intrinsic burst activity of Purkinje neurons in offspring maternally exposed to the CB1 cannabinoid agonist WIN 55212-2.  

PubMed

Burst firing plays an important role in normal neuronal function and dysfunction. In Purkinje neurons, where the firing rate and discharge pattern encode the timing signals necessary for motor function, any alteration in firing properties, including burst activity, may affect the motor output. Therefore, we examined whether maternal exposure to the cannabinoid receptor agonist WIN 55212-2 (WIN) may affect the burst firing properties of cerebellar Purkinje cells in offspring. Whole-cell somatic patch-clamp recordings were made from cerebellar slices of adult male rats that were exposed to WIN prenatally. WIN exposure during pregnancy induced long-term alterations in the burst firing behavior of Purkinje neurons in rat offspring as evidenced by a significant increase in the mean number of spikes per burst (p < 0.05) and the prolongation of burst firing activity (p < 0.01). The postburst afterhyperpolarization potential (p < 0.001), the mean intraburst interspike intervals (p < 0.001) and the mean intraburst firing frequency (p < 0.001) were also significantly increased in the WIN-treated group. Prenatal exposure to WIN enhanced the firing irregularity as reflected by a significant decrease in the coefficient of variation of the intraburst interspike interval (p < 0.05). Furthermore, whole-cell voltage-clamp recordings revealed that prenatal WIN exposure significantly enhanced Ca(2+) channel current amplitude in offspring Purkinje neurons compared to control cells. Overall, the data presented here strongly suggest that maternal exposure to cannabinoids can induce long-term changes in complex spike burst activity, which in turn may lead to alterations in neuronal output. PMID:24218023

Shabani, Mohammad; Mahnam, Amin; Sheibani, Vahid; Janahmadi, Mahyar

2014-01-01

271

Identification of two novel ?1-AR agonists using a high-throughput screening model.  

PubMed

?1-Adrenoceptors (ARs; 1A, 1B, and 1D) have been determined to perform different prominent functions in the physiological responses of the sympathetic nervous system. A high-throughput screening assay (HTS) was set up to detect ?1-AR subtype-selective agonists by a dual-luciferase reporter assay in HEK293 cells. Using the HTS assay, two novel compounds, CHE3 and CHK3, were discovered as ?1-ARs agonists in ?1-ARs expressed in HEK293 cells. These compounds also showed moderate/weak anti-proliferative activities against tested cancer cell lines. The HTS assay proposed in this study represents a potential method for discovering more ?1-AR subtype-selective ligands. PMID:25140448

Xu, Fang; Chen, Hong; He, Xuelan; Xu, Jingyi; Xu, Bingbing; Huang, Biyun; Liang, Xue; Yuan, Mu

2014-01-01

272

Neuroprotective effects of peroxisome proliferator-activated receptor alpha and gamma agonists in model of parkinsonism induced by intranigral 1-methyl-4-phenyl-1,2,3,6-tetrahyropyridine.  

PubMed

A large body of evidence suggests that peroxisome proliferator-activated receptor (PPAR) agonists may improve some of the pathological features of Parkinson's disease (PD). In the present study, we evaluated the effects of the PPAR-? agonist fenofibrate (100mg/kg) and PPAR-? agonist pioglitazone (30mg/kg) in a rat model of parkinsonism induced by intranigral 1-methyl-4-phenyl-1,2,3,6-tetrahyropyridine (MPTP). Male Wistar rats were pretreated with both drugs for 5 days and received an infusion of MPTP. The experiments were divided into two parts. First, 1, 7, 14, and 21 days after surgery, the animals were submitted to the open field test. On days 21 and 22, the rats were subjected to the forced swim test and two-way active avoidance task. In the second part of the study, 24h after neurotoxin administration, immunohistochemistry was performed to assess tyrosine hydroxylase activity. The levels of dopamine and its metabolites in the striatum were determined using high-performance liquid chromatography, and fluorescence detection was used to assess caspase-3 activation in the substantia nigra pars compacta (SNpc). Both fenofibrate as pioglitazone protected against hypolocomotion, depressive-like behavior, impairment of learning and memory, and dopaminergic neurodegeneration caused by MPTP, with dopaminergic neuron loss of approximately 33%. Fenofibrate and pioglitazone also protected against the increased activation of caspase-3, an effector enzyme of the apoptosis cascade that is considered one of the pathological features of PD. Thus, PPAR agonists may contribute to therapeutic strategies in PD. PMID:25127682

Barbiero, Janaína K; Santiago, Ronise M; Persike, Daniele Suzete; da Silva Fernandes, Maria José; Tonin, Fernanda S; da Cunha, Claudio; Lucio Boschen, Suelen; Lima, Marcelo M S; Vital, Maria A B F

2014-11-01

273

Low molecular weight, non-peptidic agonists of TrkA receptor with NGF-mimetic activity  

PubMed Central

Exploitation of the biologic activity of neurotrophins is desirable for medical purposes, but their protein nature intrinsically bears adverse pharmacokinetic properties. Here, we report synthesis and biologic characterization of a novel class of low molecular weight, non-peptidic compounds with NGF (nerve growth factor)-mimetic properties. MT2, a representative compound, bound to Trk (tropomyosin kinase receptor)A chain on NGF-sensitive cells, as well as in cell-free assays, at nanomolar concentrations and induced TrkA autophosphorylation and receptor-mediated internalization. MT2 binding involved at least two amino-acid residues within TrkA molecule. Like NGF, MT2 increased phosphorylation of extracellular signal-regulated kinase1/2 and Akt proteins and production of MKP-1 phosphatase (dual specificity phosphatase 1), modulated p38 mitogen-activated protein kinase activation, sustained survival of serum-starved PC12 or RDG cells, and promoted their differentiation. However, the intensity of such responses was heterogenous, as the ability of maintaining survival was equally possessed by NGF and MT2, whereas the induction of differentiation was expressed at definitely lower levels by the mimetic. Analysis of TrkA autophosphorylation patterns induced by MT2 revealed a strong tyrosine (Tyr)490 and a limited Tyr785 and Tyr674/675 activation, findings coherent with the observed functional divarication. Consistently, in an NGF-deprived rat hippocampal neuronal model of Alzheimer Disease, MT2 could correct the biochemical abnormalities and sustain cell survival. Thus, NGF mimetics may reveal interesting investigational tools in neurobiology, as well as promising drug candidates. PMID:22764098

Scarpi, D; Cirelli, D; Matrone, C; Castronovo, G; Rosini, P; Occhiato, E G; Romano, F; Bartali, L; Clemente, A M; Bottegoni, G; Cavalli, A; De Chiara, G; Bonini, P; Calissano, P; Palamara, A T; Garaci, E; Torcia, M G; Guarna, A; Cozzolino, F

2012-01-01

274

Anxiolytic Effects and Neuroanatomical Targets of Estrogen Receptor-? (ER?) Activation by a Selective ER? Agonist in Female Mice  

PubMed Central

The dichotomous anxiogenic and anxiolytic properties of estrogens have been reported to be mediated by two distinct neural estrogen receptors (ER), ER? and ER?, respectively. Using a combination of pharmacological and genetic approaches, we confirmed that the anxiolytic actions of estradiol are mediated by ER? and extended and these observations to demonstrate the neuroanatomical targets involved in ER? activation in these behavioral responses. We examined the effects of the biologically active S-enantiomer of diarylpropionitrile (S-DPN) on anxiety-related behavioral measures, the corresponding stress hormonal response to hypothalamo-pituitary-adrenal axis reactivity, and potential sites of neuronal activation in mutant female mice carrying a null mutation for ER? gene (?ERKO). S-DPN administration significantly reduced anxiety-like behaviors in the open field, light-dark exploration, and the elevated plus maze (EPM) in ovariectomized wild-type (WT) mice, but not in their ?ERKO littermates. Stress-induced corticosterone (CORT) and ACTH were also attenuated by S-DPN in the WT mice but not in the ?ERKO mice. Using c-fos induction after elevated plus maze, as a marker of stress-induced neuronal activation, we identified the anterodorsal medial amygdala and bed nucleus of the stria terminalis as the neuronal targets of S-DPN action. Both areas showed elevated c-fos mRNA expression with S-DPN treatment in the WT but not ?ERKO females. These studies provide compelling evidence for anxiolytic effects mediated by ER?, and its neuroanatomical targets, that send or receive projections to/from the paraventricular nucleus, providing potential indirect mode of action for the control of hypothalamo-pituitary-adrenal axis function and behaviors. PMID:22186418

Oyola, Mario G.; Portillo, Wendy; Reyna, Andrea; Foradori, Chad D.; Kudwa, Andrea; Hinds, Laura; Handa, Robert J.

2012-01-01

275

A covalently bound photoisomerizable agonist. Comparison with reversibly bound agonists at electrophorus electroplaques  

PubMed Central

After disulphide bonds are reduced with dithiothreitol, trans-3- (?-bromomethyl)-3’-[?- (trimethylammonium)methyl]azobenzene (trans-QBr) alkylates a sulfhydryl group on receptors. The membrane conductance induced by this “tethered agonist” shares many properties with that induced by reversible agonists. Equilibrium conductance increases as the membrane potential is made more negative; the voltage sensitivity resembles that seen with 50 [mu]M carbachol. Voltage- jump relaxations follow an exponential time-course; the rate constants are about twice as large as those seen with 50 ?M carbachol and have the same voltage and temperature sensitivity. With reversible agonists, the rate of channel opening increases with the frequency of agonist-receptor collisions: with tethered trans-Qbr, this rate depends only on intramolecular events. In comparison to the conductance induced by reversible agonists, the QBr-induced conductance is at least 10-fold less sensitive to competitive blockade by tubocurarine and roughly as sensitive to “open-channel blockade” bu QX-222. Light-flash experiments with tethered QBr resemble those with the reversible photoisomerizable agonist, 3,3’,bis-[?-(trimethylammonium)methyl]azobenzene (Bis-Q): the conductance is increased by cis {arrow} trans photoisomerizations and decreased by trans {arrow} cis photoisomerizations. As with Bis-Q, ligh-flash relaxations have the same rate constant as voltage-jump relaxations. Receptors with tethered trans isomer. By comparing the agonist-induced conductance with the cis/tans ratio, we conclude that each channel’s activation is determined by the configuration of a single tethered QBr molecule. The QBr-induced conductance shows slow decreases (time constant, several hundred milliseconds), which can be partially reversed by flashes. The similarities suggest that the same rate-limiting step governs the opening and closing of channels for both reversible and tethered agonists. Therefore, this step is probably not the initial encounter between agonist and receptor molecules. PMID:6246192

Lester, HA; Krouse, ME; Nass, MM; Wassermann, NH; Erlanger, BF

1980-01-01

276

Clozapine acts as an agonist at serotonin 2A receptors to counter MK-801-induced behaviors through a ?arrestin2-independent activation of Akt.  

PubMed

The G protein-coupled serotonin 2A receptor (5-HT2AR) is a prominent target for atypical antipsychotic drugs, such as clozapine. Although clozapine is known to inhibit 5-HT2AR signaling through G protein-dependent mechanisms, it differs from classic GPCR antagonists, in that it also induces 5-HT2AR internalization and activates Akt signaling via a 5-HT2AR-mediated event. In this regard, clozapine may also be considered a functionally selective agonist. The cognate neurotransmitter at the 5-HT2AR, serotonin, also induces 5-HT2AR internalization and Akt phosphorylation. Serotonin promotes interactions with the scaffolding and regulatory protein, ?arrestin2, which results in the recruitment and activation of Akt. These interactions prove to be critical for serotonin-induced, 5-HT2AR-mediated behavioral responses in mice. Herein, we sought to determine whether clozapine also utilizes ?arrestin2-mediated mechanisms to induce 5-HT2AR signaling, and whether this interaction contributes to its behavioral effects in mice. We demonstrate that unlike serotonin, clozapine-mediated 5-HT2AR internalization and Akt phosphorylation is independent of receptor interactions with ?arrestin2. Moreover, clozapine-mediated suppression of MK-801 and phencyclidine (PCP)-induced hyperlocomotion is ?arrestin2 independent, although it is dependent upon Akt. These results demonstrate that pharmacologically oppositional ligands, serotonin and clozapine, utilize differential mechanisms to achieve the same 5-HT2AR-meadiated downstream events: Akt phosphorylation and receptor internalization. Although ?arrestin2 has no effect on clozapine's actions in vivo, Akt phosphorylation is required for clozapine's efficacy in blocking MK-801- and PCP-induced models of schizophrenic behaviors in mice. PMID:24531562

Schmid, Cullen L; Streicher, John M; Meltzer, Herbert Y; Bohn, Laura M

2014-07-01

277

Retinoid X receptor and peroxisome proliferator-activated receptor-gamma agonists cooperate to inhibit matrix metalloproteinase gene expression  

PubMed Central

Introduction We recently described the ability of retinoid X receptor (RXR) ligand LG100268 (LG268) to inhibit interleukin-1-beta (IL-1-?)-driven matrix metalloproteinase-1 (MMP-1) and MMP-13 gene expression in SW-1353 chondrosarcoma cells. Other investigators have demonstrated similar effects in chondrocytes treated with rosiglitazone, a ligand for peroxisome proliferator-activated receptor-gamma (PPAR?), for which RXR is an obligate dimerization partner. The goals of this study were to evaluate the inhibition of IL-1-?-induced expression of MMP-1 and MMP-13 by combinatorial treatment with RXR and PPAR? ligands and to investigate the molecular mechanisms of this inhibition. Methods We used real-time reverse transcription-polymerase chain reaction to measure LG268- and rosiglitazone-mediated inhibition of MMP gene transcription in IL-1-?-treated SW-1353 chondrosarcoma cells. An in vitro collagen destruction assay was a functional readout of MMP collagenolytic activity. Luciferase reporter assays tested the function of a putative regulatory element in the promoters of MMP-1 and MMP-13, and chromatin immunoprecipitation (ChIP) assays detected PPAR? and changes in histone acetylation at this site. Post-translational modification of RXR and PPAR? by small ubiquitin-like modifier (SUMO) was assayed with immunoprecipitation and Western blot. Results Rosiglitazone inhibited MMP-1 and MMP-13 expression in IL-1-?-treated SW-1353 cells at the mRNA and heterogeneous nuclear RNA levels and blunted IL-1-?-induced collagen destruction in vitro. Combining LG268 and rosiglitazone had an additive inhibitory effect on MMP-1 and MMP-13 transcription and collagenolysis. IL-1-? inhibited luciferase expression in the MMP reporter assay, but rosiglitazone and LG268 had no effect. ChIP indicated that treatment with IL-1-?, but not LG268 and rosiglitazone, increased PPAR? at the proximal promoters of both MMPs. Finally, rosiglitazone or LG268 induced 'cross-SUMOylation' of both the target receptor and its binding partner, and IL-1-?-alone had no effect on SUMOylation of RXR and PPAR? but antagonized the ligand-induced SUMOylation of both receptors. Conclusions The PPAR? and RXR ligands rosiglitazone and LG268 may act through similar mechanisms, inhibiting MMP-1 and MMP-13 transcription. Combinatorial treatment activates each partner of the RXR:PPAR? heterodimer and inhibits IL-1-?-induced expression of MMP-1 and MMP-13 more effectively than either compound alone. We conclude that the efficacy of combined treatment with lower doses of each drug may minimize potential side effects of treatment with these compounds. PMID:19046432

Burrage, Peter S; Schmucker, Adam C; Ren, Yanqing; Sporn, Michael B; Brinckerhoff, Constance E

2008-01-01

278

Unique in vitro and in vivo thrombopoietic activities of ingenol 3,20 dibenzoate, a Ca(++)-independent protein kinase C isoform agonist.  

PubMed

Thrombopoiesis following severe bone marrow injury frequently is delayed, thereby resulting in life-threatening thrombocytopenia for which there are limited treatment options. The reasons for these delays in recovery are not well understood. Protein kinase C (PKC) agonists promote megakaryocyte differentiation in leukemia cell lines and primary cells. However, little is known about the megakaryopoietic effects of PKC agonists on primary CD34+ cells grown in culture or in vivo. Here we present evidence that the novel PKC isoform-selective agonist 3,20 ingenol dibenzoate (IDB) potently stimulates early megakaryopoiesis of human CD34+ cells. In contrast, broad spectrum PKC agonists failed to do so. In vivo, a single intraperitoneal injection of IDB selectively increased platelets in mice without affecting hemoglobin or white counts. Finally, IDB strongly mitigated radiation-induced thrombocytopenia, even when administered 24 hours after irradiation. Our data demonstrate that novel PKC isoform agonists such as IDB may represent a unique therapeutic strategy for accelerating the recovery of platelet counts following severe marrow injury. PMID:23284657

Racke, Frederick K; Baird, Maureen; Barth, Rolf F; Huo, Tianyao; Yang, Weilian; Gupta, Nilendu; Weldon, Michael; Rutledge, Heather

2012-01-01

279

Unique In Vitro and In Vivo Thrombopoietic Activities of Ingenol 3,20 Dibenzoate, A Ca++-Independent Protein Kinase C Isoform Agonist  

PubMed Central

Thrombopoiesis following severe bone marrow injury frequently is delayed, thereby resulting in life-threatening thrombocytopenia for which there are limited treatment options. The reasons for these delays in recovery are not well understood. Protein kinase C (PKC) agonists promote megakaryocyte differentiation in leukemia cell lines and primary cells. However, little is known about the megakaryopoietic effects of PKC agonists on primary CD34+ cells grown in culture or in vivo. Here we present evidence that the novel PKC isoform-selective agonist 3,20 ingenol dibenzoate (IDB) potently stimulates early megakaryopoiesis of human CD34+ cells. In contrast, broad spectrum PKC agonists failed to do so. In vivo, a single intraperitoneal injection of IDB selectively increased platelets in mice without affecting hemoglobin or white counts. Finally, IDB strongly mitigated radiation-induced thrombocytopenia, even when administered 24 hours after irradiation. Our data demonstrate that novel PKC isoform agonists such as IDB may represent a unique therapeutic strategy for accelerating the recovery of platelet counts following severe marrow injury. PMID:23284657

Racke, Frederick K.; Baird, Maureen; Barth, Rolf F.; Huo, Tianyao; Yang, Weilian; Gupta, Nilendu; Weldon, Michael; Rutledge, Heather

2012-01-01

280

The Cannabinoid Receptor Agonist THC Attenuates Weight Loss in a Rodent Model of Activity-Based Anorexia  

PubMed Central

Anorexia nervosa (AN) is characterized by anhedonia whereby patients experience little pleasure or reward in many aspects of their lives. Reward pathways and the endocannabionid system have been implicated in the mediation of food intake. The potential to exploit these systems to reverse weight loss is investigated in a rodent model of activity-based anorexia (ABA). The effect of subchronic (6 days) ?9-tetrahydrocannabinol (THC) treatment (0.1, 0.5, or 2.0?mg/kg/day) was assessed on chow and high-fat diet (HFD) intake, body weight, running wheel activity (RWA) as well as thermogenesis in brown adipose tissue (BAT) and lipid metabolism in white adipose tissue (WAT). Limited time availability of food and continuous access to running wheels led to anorexia and significantly reduced body weight. THC treatment (0.5 and 2.0?mg/kg/day) transiently stimulated chow intake with a moderate effect on RWA. THC (2.0?mg/kg/day) significantly reduced body weight loss and shifted markers of thermogenesis in BAT and lipid metabolism in WAT in directions consistent with reduced energy expenditure and lipolysis. THC (2.0?mg/kg/day) combined with HFD, produced a transient increase in food intake, reduction in RWA, attenuation of body weight loss, and changes in markers of thermogensis in BAT and lipolysis in the WAT. These changes were significantly greater than those seen in vehicle (HFD), vehicle (chow), and THC (chow)-treated animals. These data show for the first time the effectiveness of the endocannabinoid system in attenuating the weight loss associated with the development of ABA via a mechanism involving reduced energy expenditure. PMID:21412227

Verty, Aaron NA; Evetts, Megan J; Crouch, Geraldine J; McGregor, Iain S; Stefanidis, Aneta; Oldfield, Brian J

2011-01-01

281

Synthesis, enantioresolution, and activity profile of chiral 6-methyl-2,4-disubs-tituted pyridazin-3(2H)-ones as potent N-formyl peptide receptor agonists  

PubMed Central

A series of chiral pyridazin-3(2H)-ones was synthesized, separated as pure enantiomers, and evaluated for N-formyl peptide receptor (FPR) agonist activity. Characterization of the purified enantiomers using combined chiral HPLC and chiroptical studies (circular dichroism, allowed unambiguous assignment of the absolute configuration for each pair of enantiomers). Evaluation of the ability of racemic mixtures and purified enantiomers to stimulate intracellular Ca2+ flux in FPR-transfected HL-60 cells and human neutrophils and to induce ?-arrestin recruitment in FPR-transfected CHO-K1 cells showed that many enantiomers were potent agonists, inducing responses in the sub-micromolar to nanomolar range. Furthermore, FPRs exhibited enantiomer selectivity, generally preferring the R-(?)-forms over the S-(+)-enantiomers. Finally, we found that elongation of the carbon chain in the chiral center of the active compounds generally increased biological activity. Thus, these studies provide important new information regarding molecular features involved in FPR ligand preference and report the identification of a novel series of FPR agonists. PMID:22607879

Cilibrizzi, Agostino; Schepetkin, Igor A.; Bartolucci, Gianluca; Crocetti, Letizia; Piaz, Vittorio Dal; Giovannoni, Maria Paola; Graziano, Alessia; Kirpotina, Liliya N.; Quinn, Mark T.; Vergelli, Claudia

2012-01-01

282

GILA WOODPECKER AGONISTIC BEHAVIOR  

Microsoft Academic Search

ABSTRCT.--Agonistic behavior of Gila Woodpeckers, including vocalizations, visual displays, and other related behaviors, is described. Interactions with both con- and heterospecifics were analyzed by stochastic processes, and it is shown that the timing of aggression toward a species coincided with the time during which that species was searching for nest sites or cavities. The behavior shown toward Flickers and Starlings

GENE L. BRENOWITZ

283

Substituted acyclic sulfonamides as human cannabinoid-1 receptor inverse agonists  

Microsoft Academic Search

Sulfonamide analogues of the potent CB1R inverse agonist taranabant were prepared and optimized for potency and selectivity for CB1R. They were variably more potent than the corresponding amide analogues. The most potent representative 22 had good pharmacokinetic and brain levels, but was modestly active in blocking CB1R agonist-mediated hypothermia.

Helen E. Armstrong; Amy Galka; Linus S. Lin; Thomas J. Lanza Jr.; James P. Jewell; Shrenik K. Shah; Ravi Guthikonda; Quang Truong; Linda L. Chang; Grace Quaker; Vincent J. Colandrea; Xinchun Tong; Junying Wang; Sherry Xu; Tung M. Fong; Chun-Pyn Shen; Julie Lao; Jing Chen; Lauren P. Shearman; D. Sloan Stribling; Kimberly Rosko; Alison Strack; Sookhee Ha; Lex Van der Ploeg; Mark T. Goulet; William K. Hagmann

2007-01-01

284

Identification of a novel small-molecule agonist for human G protein-coupled receptor 3.  

PubMed

G protein-coupled receptor 3 (GPR3) is an orphan G protein-coupled receptor (GPCR) predominantly expressed in mammalian brain and oocytes. GPR3 plays important roles in these two organs and is known as a G?s-coupled receptor-activated constitutively in cells. However, the signal transduction pathway and pharmacological function of GPR3 remain unclear because of the lack of a specific ligand. By use of a human embryonic kidney 293 cell line stably expressing FLAG-GPR3-green fluorescent protein, a chemical screening for GPR3 ligands was performed using homogeneous time-resolved fluorescence cAMP assay. Diphenyleneiodonium chloride (DPI) was identified as a novel agonist of GPR3 with weak or no cross-reactivity with other GPCRs. DPI was further characterized to activate several GPR3-mediated signal transduction pathways, including Ca(2+) mobilization, cAMP accumulation, membrane recruitment of ?-arrestin2, and receptor desensitization. Parallel studies revealed that the activity of DPI is much more pronounced than sphingosine 1-phosphate, a previously reported GPR3 agonist. Our study identified a novel and specific agonist of GPR3, which provides a useful tool for further study of this orphan GPCR. PMID:24633425

Ye, Chenli; Zhang, Zhenghong; Wang, Zhilong; Hua, Qiuhong; Zhang, Ru; Xie, Xin

2014-06-01

285

Mechanisms underlying activation of transient BK current in rabbit urethral smooth muscle cells and its modulation by IP3-generating agonists.  

PubMed

We used the perforated patch-clamp technique at 37°C to investigate the mechanisms underlying the activation of a transient large-conductance K(+) (tBK) current in rabbit urethral smooth muscle cells. The tBK current required an elevation of intracellular Ca(2+), resulting from ryanodine receptor (RyR) activation via Ca(2+)-induced Ca(2+) release, triggered by Ca(2+) influx through L-type Ca(2+) (CaV) channels. Carbachol inhibited tBK current by reducing Ca(2+) influx and Ca(2+) release and altered the shape of spike complexes recorded under current-clamp conditions. The tBK currents were blocked by iberiotoxin and penitrem A (300 and 100 nM, respectively) and were also inhibited when external Ca(2+) was removed or the CaV channel inhibitors nifedipine (10 ?M) and Cd(2+) (100 ?M) were applied. The tBK current was inhibited by caffeine (10 mM), ryanodine (30 ?M), and tetracaine (100 ?M), suggesting that RyR-mediated Ca(2+) release contributed to the activation of the tBK current. When IP3 receptors (IP3Rs) were blocked with 2-aminoethoxydiphenyl borate (2-APB, 100 ?M), the amplitude of the tBK current was not reduced. However, when Ca(2+) release via IP3Rs was evoked with phenylephrine (1 ?M) or carbachol (1 ?M), the tBK current was inhibited. The effect of carbachol was abolished when IP3Rs were blocked with 2-APB or by inhibition of muscarinic receptors with the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (1 ?M). Under current-clamp conditions, bursts of action potentials could be evoked with depolarizing current injection. Carbachol reduced the number and amplitude of spikes in each burst, and these effects were reduced in the presence of 2-APB. In the presence of ryanodine, the number and amplitude of spikes were also reduced, and carbachol was without further effect. These data suggest that IP3-generating agonists can modulate the electrical activity of rabbit urethral smooth muscle cells and may contribute to the effects of neurotransmitters on urethral tone. PMID:23804200

Kyle, Barry D; Bradley, Eamonn; Large, Roddy; Sergeant, Gerard P; McHale, Noel G; Thornbury, Keith D; Hollywood, Mark A

2013-09-15

286

Expression of the chicken peroxisome proliferator-activated receptor-gamma gene is influenced by aging, nutrition, and agonist administration.  

PubMed

Peroxisome proliferatior-activated receptor-gamma (PPARgamma) is a transcription factor that modulates lipid and glucose metabolism in mammals. The aim of the present study was to investigate whether chicken PPARgamma is expressed in tissues in a similar manner to mammalian PPAR and whether it is involved in the regulation of lipid metabolism, particularly in the regulation of fat accumulation in adipose tissue and ovaries. In 30-wk-old chickens, PPARgamma mRNA was detected in most tissues that were examined. Of those tissues expressing chicken PPARgamma mRNA, the lowest expression levels were found in adipose tissue, the tissue that in mammals was shown to express the highest levels of PPARgamma mRNA. Chicken PPARgamma mRNA expression in abdominal adipose tissue tended to increase with age, as shown by higher expression levels at 6 wk than at 1 and 2 wk of age. With regard to nutritional modulation, PPARgamma mRNA levels in abdominal adipose tissue were significantly higher in broiler chickens fed for 7 d a diet containing 8% safflower oil (18:2-rich) or linseed oil (18:3-rich) compared with chickens fed a diet containing olive oil (18:1-rich). In contrast, feeding a 3% cholesterol-supplemented diet for 7 d resulted in no changes to adipose PPARgamma mRNA expression. In broiler chickens orally administered troglitazone, a PPARgamma ligand, abdominal fat pad weight and PPARgamma and lipoprotein lipase (LPL) mRNA levels were significantly increased relative to those of control chickens. Levels of PPARgamma mRNA in liver, skeletal muscle, and ovaries were increased with the onset of egg laying, whereas in adipose tissue the level of PPARgamma mRNA was decreased. These findings suggest that PPARgamma plays an important role in the regulation of fat deposition and egg production and the characteristic pattern of PPARgamma mRNA expression may be indicative of specific differences in the lipid and glucose metabolism of chickens compared with mammals. PMID:15339009

Sato, K; Fukao, K; Seki, Y; Akiba, Y

2004-08-01

287

Structure-activity-relationship study of N6-(2(4-(1H-indol-5-yl)piperazin-1-yl)ethyl)-N6-propyl-4,5,6,7-tetrahydrobenzo[d]thiazole-2,6-diamine analogues: Development of highly selective D3 dopamine receptor agonists along with a highly potent D2/D3 agonist and their pharmacological characterization  

PubMed Central

In our effort to develop multifunctional drugs against Parkinson’s disease, a structure-activity-relationship study was carried out based on our hybrid molecular template targeting D2/D3 receptors. Competitive binding with [3H]spiroperidol was used to evaluate affinity (Ki) of test compounds. Functional activity of selected compounds in stimulating [35S]GTP?S binding was assessed in CHO-cells expressing either human D2 or D3 receptors. Our results demonstrated development of highly selective compounds for D3 receptor ((?)-40; Ki D3 = 1.84 nM, D2/D3 = 583.2, (?)-45; Ki D3 = 1.09 nM, D2/D3 = 827.5). Functional data identified (?)-40 (EC50 D2 = 114 nM and D3 = 0.26 nM, D2/D3 = 438) as one of the highest D3 selective agonists known to date. In addition, high affinity, non-selective, D3 agonist, (?)-19 (EC50 D2 = 2.96 nM and D3 = 1.26 nM), was also developed. Lead compounds with antioxidant activity were evaluated using an in vivo PD animal model. PMID:22642365

Johnson, Mark; Antonio, Tamara; Reith, Maarten E. A.; Dutta, Aloke K.

2012-01-01

288

The 5-HT(4) agonists cisapride, mosapride, and CJ-033466, a Novel potent compound, exhibit different human ether-a-go-go-related gene (hERG)-blocking activities.  

PubMed

The blocking effect of three 5-HT(4) agonists, cisapride, mosapride, and the newly discovered CJ-033466 on the human ether-a-go-go-related gene (hERG) channel was studied using a whole cell patch-clamp technique in HEK293 cells. Cisapride was found to be the most potent of the hERG blockers. CJ-033466 had the widest safety margin between its hERG blocking activity and 5-HT(4) agonism among the tested compounds. This suggests a lower clinical risk of cardiac arrhythmia in CJ-033466 compared with the other 2 agonists. Therefore, CJ-033466 has the potential to be a drug with higher therapeutic efficacy and less cardiac risk than both cisapride and mosapride. PMID:17928736

Toga, Tetsuo; Kohmura, Yumi; Kawatsu, Ryoichi

2007-10-01

289

Thermotolerant Campylobacter with no or weak catalase activity isolated from dogs  

Microsoft Academic Search

ThermotolerantCampylobacter strains isolated from dog feces were characterized by phenotypical tests, DNA base composition, and DNA-DNA-hybridization. Out of 98 strains, 63 were catalase negative or weakly reacting (CNW); they were found in diarrheic as well as in healthy dogs. The CNW strains were all nalidixic-acid sensitive, hippurate negative, and grew at 42°C but not at 25°C. Seven strains were further

Karin Sandstedt; Jan Ursing; Mats Walder

1983-01-01

290

Suzaku Observes Weak Flares from IGRJ17391-3021 Representing a Common Low-Activity State in this SFXT  

NASA Technical Reports Server (NTRS)

We present an analysis of a 37-ks observation of the supergiant fast X-ray transient (SFXT) IGRJ17391 -3021 (=XTEJ1739-302) gathered with Suzaku. The source evolved from quiescence to a low-activity level culminating in three weak flares lasting approx.3 ks each in which the peak luminosity is only a factor of 5 times that of the pre-flare luminosity. The minimum observed luminosity was 1.3 x 10(exp 33) erg/s (d/2.7 kpc)(exp 2) in the 0.5-10 keV range. The weak flares are accompanied by significant changes in the spectral parameters including a column density (N(sub H) = (4.1(+0.4/-0.5)) x 10(exp 22)/sq cm) that is approx.2-9 times the absorption measured during quiescence. Accretion of obscuring clumps of stellar wind material can explain both the small flares and the increase in NH. Placing this observation in the context of the recent Swift monitoring campaign, we find that weak-flaring episodes, or at least epochs of enhanced activity just above the quiescent level but well below the moderately bright or high-luminosity outbursts, represent more than 60+/-5% of all observations in the 0.5-10keV energy range making this the most common state in the emission behavior of IGRJ17391 -3021.

Bodaghee, A.; Tomsick, J. A.; Rodriquez, J.; Chaty, S.; Pottschmidt, K.; Walter, R.; Romano, P.

2010-01-01

291

Do Agonistic Motives Matter More Than Anger? Three Studies of Cardiovascular Risk in Adolescents  

Microsoft Academic Search

Objectives: Three motivational profiles have been associated with recurring psychological stress in low-income youth and young adults: Striving to control others (agonistic striving), striving to control the self (transcendence striving), and not asserting control (dissipated striving). Agonistic striving has been associated with elevated ambulatory blood pressure during daily activities. Three studies tested the hypotheses that: (1) agonistic striving is associated

Craig K. Ewart; Gavin J. Elder; Joshua M. Smyth; Martin J. Sliwinski; Randall S. Jorgensen

2011-01-01

292

AMPK and PPAR? agonists are exercise mimetics  

PubMed Central

SUMMARY The benefits of endurance exercise on general health make it desirable to identify orally active agents that would mimic or potentiate the effects of exercise to treat metabolic diseases. Although certain natural compounds, such as reseveratrol, have endurance-enhancing activities, their exact metabolic targets remain elusive. We therefore tested the effect of pathway-specific drugs on endurance capacities of mice in a treadmill running test. We found that PPAR?/? agonist and exercise training synergistically increase oxidative myofibers and running endurance in adult mice. Because training activates AMPK and PGC1?, we then tested whether the orally active AMPK agonist AICAR might be sufficient to overcome the exercise requirement. Unexpectedly, even in sedentary mice, 4 weeks of AICAR treatment alone induced metabolic genes and enhanced running endurance by 44%. These results demonstrate that AMPK-PPAR? pathway can be targeted by orally active drugs to enhance training adaptation or even to increase endurance without exercise. PMID:18674809

Narkar, Vihang A.; Downes, Michael; Yu, Ruth T.; Embler, Emi; Wang, Yong-Xu; Banayo, Ester; Mihaylova, Maria M.; Nelson, Michael C.; Zou, Yuhua; Juguilon, Henry; Kang, Heonjoong; Shaw, Reuben; Evans, Ronald M.

2008-01-01

293

Kinetic Assembly of Near-IR Active Gold Nanoclusters using Weakly Adsorbing Polymers to Control Size  

PubMed Central

Clusters of metal nanoparticles with an overall size less than 100 nm and high metal loadings for strong optical functionality, are of interest in various fields including microelectronics, sensors, optoelectronics and biomedical imaging and therapeutics. Herein we assemble ~5 nm gold particles into clusters with controlled size, as small as 30 nm and up to 100 nm, which contain only small amounts of polymeric stabilizers. The assembly is kinetically controlled with weakly adsorbing polymers, PLA(2K)-b-PEG(10K)-b-PLA(2K) or PEG (MW = 3350), by manipulating electrostatic, van der Waals (VDW), steric, and depletion forces. The cluster size and optical properties are tuned as a function of particle volume fractions and polymer/gold ratios to modulate the interparticle interactions. The close spacing between the constituent gold nanoparticles and high gold loadings (80–85% w/w gold) produce a strong absorbance cross section of ~9×10?15 m2 in the NIR at 700 nm. This morphology results from VDW and depletion attractive interactions that exclude the weakly adsorbed polymeric stabilizer from the cluster interior. The generality of this kinetic assembly platform is demonstrated for gold nanoparticles with a range of surface charges from highly negative to neutral, with the two different polymers. PMID:20361735

Tam, Jasmine M.; Murthy, Avinash K.; Ingram, Davis R.; Nguyen, Robin; Sokolov, Konstantin V.; Johnston, Keith P.

2013-01-01

294

Inverse agonist up-regulates the constitutively active D3.49(164)Q mutant of the rat mu-opioid receptor by stabilizing the structure and blocking constitutive internalization and down-regulation.  

PubMed

We demonstrated previously that D3.49(164) mutations resulted in constitutive activation of the rat mu-opioid receptor and abolished receptor expression unless cells were pretreated with naloxone, an inverse agonist. In this study, we investigated the properties of the D3.49(164)Q mutant and the mechanisms underlying the effect of naloxone. Naloxone pretreatment up-regulated [(3)H]diprenorphine binding and protein expression of the D3.49(164)Q mutant in a time- and dose-dependent manner without affecting its mRNA level. After naloxone removal, binding and protein expression of the mutant declined with time with no effect on its mRNA level. Naloxone methiodide (a quaternary ammonium analog) caused a maximal up-regulation about 50% of the naloxone effect, indicating that naloxone acts extracellularly and intracellularly. Expression of the mutant was enhanced by inverse agonists, a neutral antagonist, and agonists, with inverse agonists being most effective. In membranes, the mutant was structurally less stable than the wild type upon incubation at 37 degrees C, and naloxone and [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin stabilized the mutant. Coexpression of the dominant-negative mutants GRK2-K220R, arrestin-2(319-418), dynamin I-K44A, rab5A-N133I or rab7-N125I partially prevented the decline in binding of the mutant after naloxone removal. Chloroquine or proteasome inhibitor I reduced the down-regulation of the mutant. These results indicate that the D3.49(164)Q mutant is constitutively internalized via G protein coupled-receptor kinase-, arrestin-2-, dynamin-, rab5-, and rab7-dependent pathways and probably trafficked through early and late endosomes into lysosomes and degraded by lysosomes and proteasomes. Naloxone up-regulates the D3.49(164)Q mutant by stabilizing the mutant protein and blocking its constitutive internalization and down-regulation. To the best of our knowledge, this represents the first comprehensive analysis of the mechanisms involved in up-regulation of constitutively active mutants by an inverse agonist. PMID:11641435

Li, J; Chen, C; Huang, P; Liu-Chen, L Y

2001-11-01

295

Structure and Function of an Irreversible Agonist-?2 Adrenoceptor complex  

PubMed Central

G protein-coupled receptors (GPCRs) are eukaryotic integral membrane proteins that modulate biological function by initiating cellular signaling in response to chemically diverse agonists. Despite recent progress in the structural biology of GPCRs1, the molecular basis for agonist binding and allosteric modulation of these proteins is poorly understood. Structural knowledge of agonist-bound states is essential for deciphering the mechanism of receptor activation, and for structure-guided design and optimization of ligands. However, the crystallization of agonist-bound GPCRs has been hampered by modest affinities and rapid off-rates of available agonists. Using the inactive structure of the human ?2 adrenergic receptor (?2AR) as a guide, we designed a ?2AR agonist that can be covalently tethered to a specific site on the receptor through a disulfide bond. The covalent ?2AR-agonist complex forms efficiently, and is capable of activating a heterotrimeric G protein. We crystallized a covalent agonist-bound ?2AR-T4L fusion protein in lipid bilayers through the use of the lipidic mesophase method2, and determined its structure at 3.5 Å resolution. A comparison to the inactive structure and an antibody-stabilized active structure (companion paper3) shows how binding events at both the extracellular and intracellular surfaces are required to stabilize an active conformation of the receptor. The structures are in agreement with long-timescale (up to 30 ?s) molecular dynamics simulations showing that an agonist-bound active conformation spontaneously relaxes to an inactive-like conformation in the absence of a G protein or stabilizing antibody. PMID:21228876

Rosenbaum, Daniel M.; Zhang, Cheng; Lyons, Joseph; Holl, Ralph; Aragao, David; Arlow, Daniel H.; Rasmussen, S?ren G. F.; Choi, Hee-Jung; DeVree, Brian T.; Sunahara, Roger K.; Chae, Pil Seok; Gellman, Samuel H.; Dror, Ron O.; Shaw, David E.; Weis, William I.; Caffrey, Martin; Gmeiner, Peter; Kobilka, Brian K.

2010-01-01

296

Pentapeptides displaying mu opioid receptor agonist and delta opioid receptor partial agonist/antagonist properties  

PubMed Central

Chronic use of mu-opioid agonists has been shown to cause neurochemical adaptations resulting in tolerance and dependence. While the analgesic effects of these drugs are mediated by mu-opioid receptors (MOR), several studies have shown that antagonism or knockdown of delta-opioid receptors (DOR) can lessen or prevent development of tolerance and dependence. Based on computational modeling of putative active and inactive conformations of MOR and DOR, we have synthesized a series of pentapeptides with the goal of developing a MOR agonist/DOR antagonist peptide with similar affinity at both receptors as a tool to probe functional opioid receptor interaction(s). The eight resulting naphthylalanine-substituted cyclic pentapeptides displayed variable mixed-efficacy profiles. The most promising peptide (9; Tyr-c(S-CH2-S)[D-Cys-Phe-2-Nal-Cys]NH2) displayed a MOR agonist and DOR partial agonist/antagonist profile and bound with equipotent affinity (Ki ~ 0.5 nM) to both receptors, but also showed kappa opioid receptor (KOR) agonist activity. PMID:19788201

Purington, Lauren C.; Pogozheva, Irina D.; Traynor, John R.; Mosberg, Henry I.

2009-01-01

297

Activation of Nociceptin\\/Orphanin FQ Peptide Receptors Disrupts Visual but Not Auditory Sensorimotor Gating in BALB\\/cByJ Mice: Comparison to Dopamine Receptor Agonists  

Microsoft Academic Search

Nociceptin\\/orphanin FQ (N\\/OFQ) peptide and its receptor (NOP receptor) have been implicated in a host of brain functions and diseases, but the contribution of this neuropeptide system to behavioral processes of relevance to psychosis has not been investigated. We examined the effect of the NOP receptor antagonists, Compound 24 and J-113397, and the synthetic agonist, Ro64-6198, on time function (2–2000

Aurelia Ces; David Reiss; Ondine Walter; Jürgen Wichmann; Eric P Prinssen; Brigitte L Kieffer; Abdel-Mouttalib Ouagazzal; A-M Ouagazzal

2012-01-01

298

Solomonsterols A and B from Theonella swinhoei. The first example of C-24 and C-23 sulfated sterols from a marine source endowed with a PXR agonistic activity.  

PubMed

The finding of new PXR modulators as potential leads for treatment of human disorders characterized by dysregulation of innate immunity and with inflammation is of wide interest. In this paper, we report the identification of the first example of natural marine PXR agonists, solomonsterols A and B, from a Theonella swinhoei sponge. The structures were determined by interpretation of NMR and ESIMS data, and the putative binding mode to PXR has been obtained through docking calculations. PMID:21141967

Festa, Carmen; De Marino, Simona; D'Auria, Maria Valeria; Bifulco, Giuseppe; Renga, Barbara; Fiorucci, Stefano; Petek, Sylvain; Zampella, Angela

2011-01-13

299

Activation of the mTOR signaling pathway in the antidepressant-like activity of the mGlu5 antagonist MTEP and the mGlu7 agonist AMN082 in the FST in rats.  

PubMed

Clinical studies have demonstrated rapid and long-lasting antidepressant effects of ketamine in depressive patients. It has been proposed that these effects are related to changes in synaptogenesis in the mechanism involving mammalian target of rapamycin (mTOR) activation. Similar mechanisms have been proposed for a group II metabotropic glutamate (mGlu) receptor antagonist, LY341495. We aimed to investigate whether other mGlu receptor ligands that produce antidepressant-like effects, namely, the mGlu5 antagonist MTEP and the mGlu7 agonist AMN082, induce the activation of mTOR signaling in the prefrontal cortex (PFC) in rats. AMN082 administered 60 min before the test increased the levels of pmTOR and pp70S6K, and the mTORC1 antagonist rapamycin reversed AMN082-induced changes in the forced swim test (FST) in rats. Furthermore, AMN082 administered 23 h before the decapitation of the rats increased the levels of synapsin I and GluR1, although it did not produce any effect in the FST at the same time point. However, MTEP induced a rapid but unsustained antidepressant-like effect, which was not related to the activation of the mTOR cascade. Finally, the antidepressant-like effects of MTEP or AMN082 were not antagonized by NBQX. In summary, the antidepressant-like activity of MTEP did not depend on the activation of mTOR signaling. However, we observed a unique feature of the mechanism of AMN082. The drug stimulated the mTOR signaling pathway and synaptic protein levels (like ketamine), while it did not induce a sustained antidepressant effect and its action was not directly dependent on AMPA receptor activation (as in classic antidepressants (ADs)). PMID:24631968

Pa?ucha-Poniewiera, Agnieszka; Szewczyk, Bernadeta; Pilc, Andrzej

2014-07-01

300

Secretome of fungus-infected aphids documents high pathogen activity and weak host response.  

PubMed

The discovery of novel secretome proteins can add to our understanding of host-pathogen interactions. Here we report a rich diversity of secreted proteins from the interaction between grain aphids (host, insect order Hemiptera) and fungi of the order Entomophthorales (insect pathogens). The proteins were identified using a unique method unbiased by known sequences or functions to screen a cDNA library constructed directly from field-sampled material. We show for the first time that fungi from the genera Pandora and Entomophthora are armed with a battery of hydrolytic enzymes for penetrating the host cuticle. This enables both access to the hemolymph and exit for sporulation. Further, they secrete enzymes, most notably a number of lipases, for digestion of easily accessible high-energy compounds in the hemolymph. In contrast, we identified only few host genes potentially involved in the interaction, indicating that aphids respond only weakly to the pathogens. These results support recent findings that aphids have a reduced immune repertoire. PMID:21156213

Grell, Morten N; Jensen, Annette B; Olsen, Peter B; Eilenberg, Jørgen; Lange, Lene

2011-04-01

301

Evidence for postsynaptic dopamine agonist effects of BHT 920 in the presence of the dopamine D-1 agonist SKF 38393  

Microsoft Academic Search

The ability of B-HT 920, a selective dopamine (DA) D-2 agonist, to stimulate postsynaptic DA receptors in brain was evaluated by assessing its ability to induce stereotypy and to increase locomotor activity in rats. When administered alone, B-HT 920 (0.03–3.0 mg\\/kg) did not induce stereotypy and produced only inhibition of locomotor activity, suggesting a lack of postsynaptic DA agonist actions.

Leonard T. Meltzer; James N. Wiley; Ann E. Williams; Thomas G. Heffner

1988-01-01

302

The sigma-1 receptor agonist 4-phenyl-1-(4-phenylbutyl) piperidine (PPBP) protects against newborn excitotoxic brain injury by stabilizing the mitochondrial membrane potential in vitro and inhibiting microglial activation in vivo.  

PubMed

Premature birth represents a clinical situation of risk for brain injury. The diversity of pathophysiological processes complicates efforts to find effective therapeutic strategies. Excitotoxicity is one important factor in the pathogenesis of preterm brain injury. The observation that sigma-1 receptor agonists possess neuroprotective potential, at least partly mediated by a variety of anti-excitotoxic mechanisms, has generated great interest in targeting those receptors to counteract brain injury. The objective of this study was to evaluate the effect of the highly specific sigma-1 receptor agonist, 4-phenyl-1-(4-phenylbutyl) piperidine (PPBP) to protect against excitotoxic developmental brain injury in vivo and in vitro. Primary hippocampal neurons were pre-treated with PPBP before glutamate was applied and subsequently analyzed for cell death (PI/calcein AM), mitochondrial activity (TMRM) and morphology of the neuronal network (WGA) using confocal microscopy. Using an established neonatal mouse model we also determined whether systemic injection of PPBP significantly attenuates excitotoxic brain injury. PPBP significantly reduced neuronal cell death in primary hippocampal neurons exposed to glutamate. Neurons treated with PPBP showed a less pronounced loss of mitochondrial membrane potential and fewer morphological changes after glutamate exposure. A single intraperitoneal injection of PPBP given one hour after the excitotoxic insult significantly reduced microglial cell activation and lesion size in cortical gray and white matter. The present study provides strong support for the consideration of sigma-1 receptor agonists as a candidate therapy for the reduction of neonatal excitotoxic brain lesions and might offer a novel target to counteract developmental brain injury. PMID:25111531

Wegleiter, Karina; Hermann, Martin; Posod, Anna; Wechselberger, Karina; Stanika, Ruslan I; Obermair, Gerald J; Kiechl-Kohlendorfer, Ursula; Urbanek, Martina; Griesmaier, Elke

2014-11-01

303

Novel Human Interleukin-15 Agonists  

PubMed Central

IL-15 is an immunostimulatory cytokine trans-presented with the IL-15 receptor ? chain to the shared IL-2/IL-15R? and common ? chains displayed on the surface of T cells and NK cells. To further define the functionally important regions of this cytokine, activity and binding studies were conducted on human IL-15 muteins generated by site-directed mutagenesis. Amino acid substitutions of the asparagine residue at position 72, which is located at the end of helix C, were found to provide both partial agonist and superagonist activity, with various non-conservative substitutions providing enhanced activity. Particularly, the N72D substitution provided a 4–5 fold increased in biological activity of the IL-15 mutein compared to the native molecule based on proliferations assays with cells bearing human IL-15R? and common ? chains. The IL-15N72D mutein exhibited superagonist activity through improved binding ability to the human IL-15R? chain. However, the enhanced potency of IL-15N72D was not observed with cells expressing the mouse IL-15R?-IL-15R?-?c complex suggesting that this effect is specific to human IL-15 receptor. The enhanced biological activity of IL-15N72D was associated with more intense phosphorylation of Jak1 and Stat5 and better anti-apoptotic activity compared to the wild-type IL-15. IL-15N72D superagonist activity was also preserved when linked to a single-chain T cell receptor domain to generate a tumor-specific fusion protein. Thus, the human IL-15 superagonist muteins and fusions may create opportunities to construct more efficacious immunotherapeutic agents with clinical utility. PMID:19710453

Zhu, Xiaoyun; Marcus, Warren D.; Xu, Wenxin; Lee, Hyung-Il; Han, Kaiping; Egan, Jack O.; Yovandich, Jason L.; Rhode, Peter R.; Wong, Hing C.

2009-01-01

304

Creatine Kinase Activity Weakly Correlates to Volume Completed Following Upper Body Resistance Exercise  

ERIC Educational Resources Information Center

In the current study, we examined the relationship between serum creatine kinase (CK) activity following upper body resistance exercise with a 1- or 3-min rest between sets. Twenty men performed two sessions, each consisting of four sets with a 10-repetition maximum load. The results demonstrated significantly greater volume for the 3-min…

Machado, Marco; Willardson, Jeffrey M.; Silva, Dailson P.; Frigulha, Italo C.; Koch, Alexander J.; Souza, Sergio C.

2012-01-01

305

Topical Application of a Platelet Activating Factor Receptor Agonist Suppresses Phorbol Ester-Induced Acute and Chronic Inflammation and Has Cancer Chemopreventive Activity in Mouse Skin  

PubMed Central

Platelet activating factor (PAF) has long been associated with acute edema and inflammatory responses. PAF acts by binding to a specific G-protein coupled receptor (PAF-R, Ptafr). However, the role of chronic PAF-R activation on sustained inflammatory responses has been largely ignored. We recently demonstrated that mice lacking the PAF-R (Ptafr-/- mice) exhibit increased cutaneous tumorigenesis in response to a two-stage chemical carcinogenesis protocol. Ptafr-/- mice also exhibited increased chronic inflammation in response to phorbol ester application. In this present study, we demonstrate that topical application of the non-hydrolysable PAF mimetic (carbamoyl-PAF (CPAF)), exerts a potent, dose-dependent, and short-lived edema response in WT mice, but not Ptafr -/- mice or mice deficient in c-Kit (c-KitW-sh/W-sh mice). Using an ear inflammation model, co-administration of topical CPAF treatment resulted in a paradoxical decrease in both acute ear thickness changes associated with a single PMA application, as well as the sustained inflammation associated with chronic repetitive PMA applications. Moreover, mice treated topically with CPAF also exhibited a significant reduction in chemical carcinogenesis. The ability of CPAF to suppress acute and chronic inflammatory changes in response to PMA application(s) was PAF-R dependent, as CPAF had no effect on basal or PMA-induced inflammation in Ptafr-/- mice. Moreover, c-Kit appears to be necessary for the anti-inflammatory effects of CPAF, as CPAF had no observable effect in c-KitW-sh/W-sh mice. These data provide additional evidence that PAF-R activation exerts complex immunomodulatory effects in a model of chronic inflammation that is relevant to neoplastic development. PMID:25375862

Ocana, Jesus A.; DaSilva-Arnold, Sonia C.; Bradish, Joshua R.; Richey, Justin D.; Warren, Simon J.; Rashid, Badri; Travers, Jeffrey B.; Konger, Raymond L.

2014-01-01

306

The effects of metabotropic glutamate receptor 7 allosteric agonist N,N'-dibenzhydrylethane-1,2-diamine dihydrochloride on developmental sevoflurane neurotoxicity: role of extracellular signal-regulated kinase 1 and 2 mitogen-activated protein kinase signaling pathway.  

PubMed

The present study was designed to evaluate the possible neuroprotective effects of metabotropic glutamate receptor (mGluR7) allosteric agonist N,N'-dibenzhydrylethane-1,2-diamine dihydrochloride (AMN082) on developmental sevoflurane neurotoxicity. To achieve the objective, hippocampal cultures (7 DIV, 7 day in vitro) were treated with different doses of L-(+)-2-amino-4-phosphonobutyric acid (L-AP4, an agonist of group III mGluRs), (RS)-?-Methylserine-O-phosphate (MSOP, an antagonist of group III mGluRs), AMN082 or cis-2-[[(3,5-dichlorophenyl)amino]carbonyl]cyclohexanecarboxylic acid (VU0155041, an agonist of mGluR4) before exposed to sevoflurane. Cell apoptosis were determined by flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL)-staining. For in vivo study, rat pups (7 PND, 7 postnatal day) were injected with AMN082, L-AP4 or saline before sevoflurane exposure. Extracellular signal-regulated kinase 1 and 2 (ERK1/2), c-Jun N-terminal kinase (JNK), p38, caspase-3, Bcl-2, and Bax were detected by Western blot. The locomotor activity and cognitive functions were evaluated by open-field test and Morris water maze (MWM), respectively. We found that L-AP4 prevented sevoflurane-induced cell apoptosis, but MSOP promoted. Specially, application of AMN082 contributed to the relief of sevoflurane-induced apoptosis in vitro, whereas VU0155041 did not. In addition, sevoflurane treatment led to a decrease of Bcl-2 and an increase of caspase-3 and Bax, which were mitigated by AMNO82 in vivo. Moreover, we showed that sevoflurane treatment resulted in a remarkable suppression of phospho-ERK1/2, which was restored by AMN082. Application of U0126 (an inhibitor of MEK) abolished the neuroprotective effects of AMN082 on sevoflurane neurotoxicity both in vitro and in vivo. In addition, sevoflurane exposure also led to an increase of phospho-JNK, but SP600125 (an inhibitor of JNK) did not attenuate sevoflurane-induced apoptosis. The total and phosphorylated p38 remained unchanged in sevoflurane-treated rat pups. Finally, AMN082 improved the learning and memory defects caused by postnatal sevoflurane exposure without alternations in emotion or locomotor activity. These preliminary data indicate that AMN082 may protect immature brain against sevoflurane neurotoxicity, and the ERK1/2 MAP kinase signaling is likely to be involved. Further studies are needed to fully assess the neuroprotective role of mGluR7 agonist AMN082 in developmental anesthetic neurotoxicity. PMID:22244976

Wang, W-Y; Wang, H; Luo, Y; Jia, L-J; Zhao, J-N; Zhang, H-H; Ma, Z-W; Xue, Q-S; Yu, B-W

2012-03-15

307

Dopamine Agonists and the Suppression of Impulsive Motor Actions in Parkinson's Disease  

PubMed Central

The suppression of spontaneous motor impulses is an essential facet of cognitive control that is linked to frontal-basal ganglia circuitry. Basal ganglia dysfunction caused by Parkinson’s disease (PD) disrupts the proficiency of action suppression, but how pharmacotherapy for PD impacts impulsive motor control is poorly understood. Dopamine agonists improve motor symptoms of PD, but can also provoke impulsive-compulsive behaviors (ICB). We investigated whether dopamine agonist medication has a beneficial or detrimental effect on impulsive action control in thirty-eight PD patients, half of whom had current ICB. Participants performed the Simon conflict task, which measures susceptibility to acting on spontaneous action impulses as well as the proficiency of suppressing these impulses. Compared to an off agonist state, patients on their agonist were no more susceptible to reacting impulsively, but were less proficient at suppressing the interference from the activation of impulsive actions. Importantly, agonist effects depended on baseline performance in the off agonist state; more proficient suppressors off agonist experienced a reduction in suppression on agonist, whereas less proficient suppressors off agonist showed improved suppression on agonist. Patients with active ICB were actually less susceptible to making fast, impulsive response errors than patients without ICB, suggesting that behavioral problems in this subset of patients may be less related to impulsivity in motor control. Our findings provide further evidence that dopamine agonist medication impacts specific cognitive control processes and that the direction of its effects depends on individual differences in performance off medication. PMID:22571461

Wylie, S.A.; Claassen, D.O.; Huizenga, H.M.; Schewel, K.D.; Ridderinkhof, K.R.; Bashore, T.R.; van den Wildenberg, W.P.M.

2012-01-01

308

Mutational Analysis of Cysteine Residues of the Insect Odorant Co-receptor (Orco) from Drosophila melanogaster Reveals Differential Effects on Agonist- and Odorant-tuning Receptor-dependent Activation.  

PubMed

Insect odorant receptors are heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor (ORx) and a highly conserved co-receptor known as Orco. Orco is found only in insects, and very little is known about its structure and the mechanism leading to channel activation. In the absence of an ORx, Orco forms homomeric channels that can be activated by a synthetic agonist, VUAA1. Drosophila melanogaster Orco (DmelOrco) contains eight cysteine amino acid residues, six of which are highly conserved. In this study, we replaced individual cysteine residues with serine or alanine and expressed Orco mutants in Flp-In 293 T-Rex cells. Changes in intracellular Ca(2+) levels were used to determine responses to VUAA1. Replacement of two cysteines (Cys-429 and Cys-449) in a predicted intracellular loop (ICL3), individually or together, gave variants that all showed similar increases in the rate of response and sensitivity to VUAA1 compared with wild-type DmelOrco. Kinetic modeling indicated that the response of the Orco mutants to VUAA1 was faster than wild-type Orco. The enhanced sensitivity and faster response of the Cys mutants was confirmed by whole-cell voltage clamp electrophysiology. In contrast to the results from direct agonist activation of Orco, the two cysteine replacement mutants when co-expressed with a tuning receptor (DmelOR22a) showed an ?10-fold decrease in potency for activation by 2-methyl hexanoate. Our work has shown that intracellular loop 3 is important for Orco channel activation. Importantly, this study also suggests differences in the structural requirements for the activation of homomeric and heteromeric Orco channel complexes. PMID:25271160

Turner, Rebecca M; Derryberry, Stephen L; Kumar, Brijesh N; Brittain, Thomas; Zwiebel, Laurence J; Newcomb, Richard D; Christie, David L

2014-11-14

309

Fast Skeletal Muscle Troponin Activation Increases Force of Mouse Fast Skeletal Muscle and Ameliorates Weakness Due to Nebulin-Deficiency  

PubMed Central

The effect of the fast skeletal muscle troponin activator, CK-2066260, on calcium-induced force development was studied in skinned fast skeletal muscle fibers from wildtype (WT) and nebulin deficient (NEB KO) mice. Nebulin is a sarcomeric protein that when absent (NEB KO mouse) or present at low levels (nemaline myopathy (NM) patients with NEB mutations) causes muscle weakness. We studied the effect of fast skeletal troponin activation on WT muscle and tested whether it might be a therapeutic mechanism to increase muscle strength in nebulin deficient muscle. We measured tension–pCa relations with and without added CK-2066260. Maximal active tension in NEB KO tibialis cranialis fibers in the absence of CK-2066260 was ?60% less than in WT fibers, consistent with earlier work. CK-2066260 shifted the tension-calcium relationship leftwards, with the largest relative increase (up to 8-fold) at low to intermediate calcium levels. This was a general effect that was present in both WT and NEB KO fiber bundles. At pCa levels above ?6.0 (i.e., calcium concentrations <1 µM), CK-2066260 increased tension of NEB KO fibers to beyond that of WT fibers. Crossbridge cycling kinetics were studied by measuring ktr (rate constant of force redevelopment following a rapid shortening/restretch). CK-2066260 greatly increased ktr at submaximal activation levels in both WT and NEB KO fiber bundles. We also studied the sarcomere length (SL) dependence of the CK-2066260 effect (SL 2.1 µm and 2.6 µm) and found that in the NEB KO fibers, CK-2066260 had a larger effect on calcium sensitivity at the long SL. We conclude that fast skeletal muscle troponin activation increases force at submaximal activation in both wildtype and NEB KO fiber bundles and, importantly, that this troponin activation is a potential therapeutic mechanism for increasing force in NM and other skeletal muscle diseases with loss of muscle strength. PMID:23437068

Lee, Eun-Jeong; De Winter, Josine M.; Buck, Danielle; Jasper, Jeffrey R.; Malik, Fady I.; Labeit, Siegfried; Ottenheijm, Coen A.; Granzier, Henk

2013-01-01

310

Novel endogenous peptide agonists of cannabinoid receptors  

PubMed Central

Hemopressin (Hp), a 9-residue ?-hemoglobin-derived peptide, was previously reported to function as a CB1 cannabinoid receptor antagonist (1). In this study, we report that mass spectrometry (MS) data from peptidomics analyses of mouse brain extracts identified N-terminally extended forms of Hp containing either three (RVD-Hp?) or two (VD-Hp?) additional amino acids, as well as a ?-hemoglobin-derived peptide with sequence similarity to that of hemopressin (VD-Hp?). Characterization of the ?-hemoglobin-derived peptides using binding and functional assays shows that in contrast to Hp, which functions as a CB1 cannabinoid receptor antagonist, both RVD-Hp? and VD-Hp? function as agonists. Studies examining the increase in the phosphorylation of ERK1/2 levels or release of intracellular Ca2+ indicate that these peptides activate a signal transduction pathway distinct from that activated by the endocannabinoid, 2-arachidonoylglycerol, or the classic CB1 agonist, Hu-210. This finding suggests an additional mode of regulation of endogenous cannabinoid receptor activity. Taken together, these results suggest that the CB1 receptor is involved in the integration of signals from both lipid- and peptide-derived signaling molecules.—Gomes, I., Grushko, J. S., Golebiewska, U., Hoogendoorn, S., Gupta, A., Heimann, A. S., Ferro, E. S., Scarlata, S., Fricker, L. D., Devi, L. A. Novel endogenous peptide agonists of cannabinoid receptors. PMID:19380512

Gomes, Ivone; Grushko, Julia S.; Golebiewska, Urszula; Hoogendoorn, Sascha; Gupta, Achla; Heimann, Andrea S.; Ferro, Emer S.; Scarlata, Suzanne; Fricker, Lloyd D.; Devi, Lakshmi A.

2009-01-01

311

Experiments in Weak Acid Dissociation and Theories of Activated Rate Processes.  

NASA Astrophysics Data System (ADS)

Activated chemical reactions in condensed media constitute the most important type of chemistry near the earth's surface. With the help and intuition provided by the successes of gas phase chemistry, two technological advances, subpicosecond time-resolved spectroscopy and theoretical calculations using super computers, have brought the goal of a molecular level understanding in condensed phase chemistry closer to view. In the experimental studies, lifetime and quantum yield measurements were performed on the excited states of 1-naphthol-2-sulfonic acid potassium salt (1-ROH-2-S) and its associated anion in aqueous solutions. In comparison to 1-naphthol, the intramolecular hydrogen bonding in the sulfonate derivative sterically reduces the extramolecular proton dissociation and recombination rates. Despite the large differences between excited state rates in 1-ROH -2-S and those in 1- and 2-naphthol, proton dissociation in all these molecules is controlled by reorientational motions of the adjacent water and requires a special (H _2O)_{4+/- 1} cluster as the proton acceptor. These findings support the Robinson-Lee-Moore hydration model for proton dissociation in aqueous environments. In the theoretical studies, two generalized theories of activated chemical reactions were developed using space-dependent friction. One method used the Carmeli-Nitzan approach, which is based on a Langevin equation. The second method employed the recent theory of Pollak-Grabert-Hanggi based on a Hamiltonian approach. The latter theory gave rise to interesting scaling properties in certain limits.

Krishnan, Rajalakshmi

312

An agonist sensitive, quick and simple cell-based signaling assay for determination of ligands mimicking prostaglandin E2 or E1 activity through subtype EP1 receptor: Suitable for high throughput screening  

PubMed Central

Background Conventionally the active ingredients in herbal extracts are separated into individual components, by fractionation, desalting, and followed by high-performance liquid chromatography (HPLC). In this study we have tried to directly screen water-soluble fractions of herbs with potential active ingredients before purification or extraction. We propose that the herbal extracts mimicking prostaglandin E1 (PGE1) and E2 (PGE2) can be identified in the water-soluble non-purified fraction. PGE1 is a potent anti-inflammatory molecule used for treating peripheral vascular diseases while PGE2 is an inflammatory molecule. Methods We used cell-based assays (CytoFluor multi-well plate reader and fluorescence microscopy) in which a calcium signal was generated by the recombinant EP1 receptor stably expressed in HEK293 cells (human embryonic kidney). PGE1 and PGE2 were tested for their ability to generate a calcium signal. Ninety-six water soluble fractions of Treasures of the east (single Chinese herb dietary supplements) were screened. Results After screening, the top ten stimulators were identified. The identified herbs were then desalted and the calcium fluorescent signal reconfirmed using fluorescence microscopy. Among these top ten agonists identified, seven stimulated the calcium signaling (1-40 ?M concentration) using fluorescence microscopy. Conclusions Fluorescence microscopy and multi-well plate readers can be used as a target specific method for screening water soluble fractions with active ingredients at a very early stage, before purification. Our future work consists of purifying and separating the active ingredients and repeating fluorescence microscopy. Under ordinary circumstances we would have to purify the compounds first and then test all the extracts from 96 herbs. Conventionally, for screening natural product libraries, the procedure followed is the automated separation of all constituents into individual components using fractionation and high performance liquid chromatography. We, however, demonstrated that the active ingredients of the herbal extracts can be tested before purification using an agonist sensitive, quick and simple cell-based signaling assay for ligands mimicking the agonists, PGE1 and PGE2. PMID:21299883

2011-01-01

313

The novel ?3-adrenoceptor agonist mirabegron reduces carbachol-induced contractile activity in detrusor tissue from patients with bladder outflow obstruction with or without detrusor overactivity.  

PubMed

?(3)-Adrenoceptors are major players in detrusor relaxation and have been suggested as a new putative target for the treatment of overactive bladder syndrome. We determined the effects of mirabegron (YM178), a novel ?(3)-adrenoceptor agonist, on carbachol-induced tone in isolated human detrusor preparations from patients with bladder outflow obstruction (BOO) with and without detrusor overactivity (DO), and from patients with normal bladder function. We compared the effects to those of isoprenaline, a non-selective ?-adrenoceptor agonist. Detrusor specimens were obtained from patients with benign prostatic hyperplasia undergoing cystoscopy and from patients undergoing radical prostatectomy/cystectomy (in total 33 donors). Detrusor contractility was evaluated by organ bath studies and strips were incubated with carbachol (1?M) to induce and enhance tension. Both mirabegron and isoprenaline reduced carbachol-induced tone in tissues from all groups. Isoprenaline decreased tension with higher potency than mirabegron in normal, BOO and BOO+DO detrusor strips with pIC(50) values of 7.49 ± 0.16 vs. 6.23 ± 0.26 (P=0.0002), 6.89 ± 0.34 vs. 6.04 ± 0.31 (P=0.01), and 6.57 ± 0.20 vs. 5.41 ± 0.08 (P<0.0001, n=4), respectively. The maximal relaxant effect of isoprenaline and mirabegron in the normal, BOO and BOO+DO detrusor was 37.7 ± 14.4% and 36.1 ± 23.3%, 14.4 ± 12.2% vs. 33.4 ± 21.0% and 18.3 ± 10.0% vs. 28.3 ± 12.2% (n=4, P>0.05), respectively. Mirabegron and isoprenaline reduced carbachol-induced tone in both normal bladders and obstructed bladder with and without DO. Isoprenaline had higher potency than mirabegron, but the efficacy of mirabegron effect was the same as that of isoprenaline. PMID:23246623

Svalø, Julie; Nordling, Jørgen; Bouchelouche, Kirsten; Andersson, Karl-Erik; Korstanje, Cees; Bouchelouche, Pierre

2013-01-15

314

Postsynaptic dopamine (DA) receptor stimulator properties of the putative DA autoreceptor-selective agonist BHT 920 uncovered by co-treatment with the D-1 agonist SK&F 38393  

Microsoft Academic Search

Postsynaptic dopaminergic behavioural effects of D-2 agonists can be promoted by concomitant D-1 receptor activation. The present experiment explored whether such effects could be elicited by the putative autoreceptor-selective D-2 agonist B-HT 920, when combined with the D-1 agonist SK&F 38393. Except for occasional jerks induced by B-HT 920, neither agonist caused significant dopaminergic stimulation when given separately, whereas combined

S. Hjorth; A. Carlsson

1987-01-01

315

Novel nonsecosteroidal VDR agonists with phenyl-pyrrolyl pentane skeleton.  

PubMed

In order to find the vitamin D receptor (VDR) ligand whose VDR agonistic activity is separated from the calcemic activity sufficiently, novel nonsecosteroidal analogs with phenyl-pyrrolyl pentane skeleton were synthesized and evaluated for the VDR binding affinity, antiproliferative activity in vitro and serum calcium raising ability in vivo (tacalcitol used as control). Among them, several compounds showed varying degrees of VDR agonistic and growth inhibition activities of the tested cell lines. The most effective compound 2g (EC??: 1.06 nM) exhibited stronger VDR agonistic activity than tacalcitol (EC??: 7.05 nM), inhibited the proliferations of HaCaT and MCF-7 cells with IC?? of 2.06 ?M and 0.307 ?M (tacalcitol: 2.07 ?M and 0.057 ?M) and showed no significant effect on serum calcium. PMID:24099996

Shen, Wei; Xue, Jingwei; Zhao, Zekai; Zhang, Can

2013-11-01

316

Comparative Transcriptional Network Modeling of Three PPAR-?\\/? Co-Agonists Reveals Distinct Metabolic Gene Signatures in Primary Human Hepatocytes  

Microsoft Academic Search

AimsTo compare the molecular and biologic signatures of a balanced dual peroxisome proliferator-activated receptor (PPAR)-?\\/? agonist, aleglitazar, with tesaglitazar (a dual PPAR-?\\/? agonist) or a combination of pioglitazone (Pio; PPAR-? agonist) and fenofibrate (Feno; PPAR-? agonist) in human hepatocytes.Methods and ResultsGene expression microarray profiles were obtained from primary human hepatocytes treated with EC50-aligned low, medium and high concentrations of the

Renée Deehan; Pia Maerz-Weiss; Natalie L. Catlett; Guido Steiner; Ben Wong; Matthew B. Wright; Gil Blander; Keith O. Elliston; William Ladd; Maria Bobadilla; Jacques Mizrahi; Carolina Haefliger; Alan Edgar

2012-01-01

317

Active-to-absorbing-state phase transition in the presence of fluctuating environments: weak and strong dynamic scaling.  

PubMed

We investigate the scaling properties of phase transitions between survival and extinction (active-to-absorbing-state phase transition, AAPT) in a model that by itself belongs to the directed percolation (DP) universality class, interacting with a spatiotemporally fluctuating environment having its own nontrivial dynamics. We model the environment by (i) a randomly stirred fluid, governed by the Navier-Stokes (NS) equation, and (ii) a fluctuating surface, described either by the Kardar-Parisi-Zhang (KPZ) or the Edward-Wilkinson (EW) equations. We show, by using a one-loop perturbative field theoretic setup that, depending upon the spatial scaling of the variance of the external forces that drive the environment (i.e., the NS, KPZ, or EW equations), the system may show weak or strong dynamic scaling at the critical point of active-to-absorbing-state phase transitions. In the former case AAPT displays scaling belonging to the DP universality class, whereas in the latter case the universal behavior is different. PMID:23005737

Sarkar, Niladri; Basu, Abhik

2012-08-01

318

Opioid peptide receptor studies. 10. Nor-BNI differentially inhibits kappa receptor agonist-induced G-protein activation in the guinea pig caudate: further evidence of kappa receptor heterogeneity.  

PubMed

There is strong evidence supporting the existence of multiple kappa receptors. Previous studies proposed that U69,593 and (+)-tifluadom act on different kappa receptor subtypes, kappa(1) (kappa(1)) and kappa(2) (kappa(2)), respectively. In this study, we investigated the effects of the kappa selective antagonist nor-binaltorphimine (Nor-BNI) on U69,593- and (+)-tifluadom-induced receptor-mediated stimulation of [(35)S]-GTP-gamma-S binding in the guinea pig caudate. The IC(50) value of Nor-BNI in the presence of a stimulating concentration of U69,593 (1 microM) was 0.19+/-0.02; while the IC(50) for Nor-BNI in the presence of (+)-tifluadom (1 microM) was 13.9+/- 1.62 nM. The mu-opioid receptor antagonist CTAP (10,000 nM) significantly reduced (+)-tifluadom-stimulated [(35)S]-GTP-gamma-S binding in rat brain sections and guinea pig brain membranes, indicating that (+)-tifluadom has mu agonist activity. Under conditions in which the mu agonist activity of (+)-tifluadom was blocked by 1000 nM CTAP the Ki value for Nor-BNI for inhibition of U69,593-stimulated [(35)S]-GTP-gamma-S binding was 0.036+/-.004 nM, whereas, its Ki value for the (+)-tifluadom-stimulated [(35)S]-GTP-gamma-S binding was 0.27+/-.015 nM. These results suggest that (+)-tifluadom and U69,593 activate pharmacologically different receptors. This study provides functional evidence in support of kappa receptor heterogeneity. PMID:10529720

Heyliger, S O; Jackson, C; Rice, K C; Rothman, R B

1999-12-15

319

Identification of Hydroxybenzoic Acids as Selective Lactate Receptor (GPR81) Agonists with Antilipolytic Effects.  

PubMed

Following the characterization of the lactate receptor (GPR81), a focused screening effort afforded 3-hydroxybenzoic acid 1 as a weak agonist of both GPR81 and GPR109a (niacin receptor). An examination of structurally similar arylhydroxy acids led to the identification of 3-chloro-5-hydroxybenzoic acid 2, a selective GPR81 agonist that exhibited favorable in vivo effects on lipolysis in a mouse model of obesity. PMID:24900524

Dvorak, Curt A; Liu, Changlu; Shelton, Jonathan; Kuei, Chester; Sutton, Steven W; Lovenberg, Timothy W; Carruthers, Nicholas I

2012-08-01

320

Identification of Hydroxybenzoic Acids as Selective Lactate Receptor (GPR81) Agonists with Antilipolytic Effects  

PubMed Central

Following the characterization of the lactate receptor (GPR81), a focused screening effort afforded 3-hydroxybenzoic acid 1 as a weak agonist of both GPR81 and GPR109a (niacin receptor). An examination of structurally similar arylhydroxy acids led to the identification of 3-chloro-5-hydroxybenzoic acid 2, a selective GPR81 agonist that exhibited favorable in vivo effects on lipolysis in a mouse model of obesity. PMID:24900524

2012-01-01

321

Daidzein and genistein glucuronides in vitro are weakly estrogenic and activate human natural killer cells at nutritionally relevant concentrations.  

PubMed

Daidzein and genistein glucuronides (DG and GG), major isoflavone metabolites, may be partly responsible for biological effects of isoflavones, such as estrogen receptor binding and natural killer cell (NK) activation or inhibition. DG and GG were synthesized using 3-methylcholanthrene-induced rat liver microsomes. The Km and Vmax for daidzein and genistein were 9.0 and 7.7 micromol/L, and 0.7 and 1.6 micromol/(mg protein. min), respectively. The absence of ultraviolet absorbance maxima shifts in the presence of sodium acetate confirmed that the synthesized products were 7-O-glucuronides. DG and GG were further purified by a Sephadex LH-20 column. DG and GG competed with the binding of 17beta-(3H) estradiol to estrogen receptors of B6D2F1 mouse uterine cytosol. The concentrations required for 50% displacement of 17beta-(3H) estradiol (CB50) were: 17beta-estradiol, 1.34 nmol/L; diethylstilbestrol, 1.46 nmol/L; daidzein, 1.6 micromol/L; DG, 14.7 micromol/L; genistein, 0.154 micromol/L; GG, 7.27 micromol/L. In human peripheral blood NK cells, genistein at <0.5 micromol/L and DG and GG at 0.1-10 micromol/L enhanced NK cell-mediated K562 cancer cell killing significantly (P < 0.05). At > 0.5 micromol/L, genistein inhibited NK cytotoxicity significantly (P < 0.05). The glucuronides only inhibited NK cytotoxicity at 50 micromol/L. Isoflavones, and especially the isoflavone glucuronides, enhanced activation of NK cells by interleukin-2 (IL-2), additively. At physiological concentrations, DG and GG were weakly estrogenic, and they activated human NK cells in nutritionally relevant concentrations in vitro, probably at a site different from IL-2 action. PMID:10024618

Zhang, Y; Song, T T; Cunnick, J E; Murphy, P A; Hendrich, S

1999-02-01

322

Porphyromonas gingivalis Lipopolysaccharide Weakly Activates M1 and M2 Polarized Mouse Macrophages but Induces Inflammatory Cytokines.  

PubMed

Porphyromonas gingivalis is associated with chronic periodontitis, an inflammatory disease of the tooth's supporting tissues. Macrophages are important in chronic inflammatory conditions, infiltrating tissue and becoming polarized to an M1 or M2 phenotype. As responses to stimuli differ between these phenotypes, we investigated the effect of P. gingivalis lipopolysaccharide (LPS) on M1 and M2 macrophages. M1 and M2 polarized macrophages were produced from murine bone marrow macrophages (BMM?) primed with gamma interferon (IFN-?) or interleukin-4 (IL-4), respectively, and incubated with a low or high dose of P. gingivalis LPS or control TLR2 and TLR4 ligands. In M1-M?, the high dose of P. gingivalis LPS (10 ?g/ml) significantly increased the expression of CD40, CD86, inducible nitric oxide synthase, and nitric oxide secretion. The low dose of P. gingivalis LPS (10 ng/ml) did not induce costimulatory or antibacterial molecules but did increase the secretion of IL-1?, IL-6, IL-12p40, IL-12p70, and tumor necrosis factor alpha (TNF-?). P. gingivalis LPS marginally increased the expression of CD206 and YM-1, but it did enhance arginase expression by M2-M?. Furthermore, the secretion of the chemokines KC, RANTES, eotaxin, and MCP-1 from M1, M2, and nonpolarized M? was enhanced by P. gingivalis LPS. TLR2/4 knockout macrophages combined with the TLR activation assays indicated that TLR2 is the main activating receptor for P. gingivalis LPS and whole cells. In conclusion, although P. gingivalis LPS weakly activated M1-M? or M2-M? compared to control TLR ligands, it induced the secretion of inflammatory cytokines, particularly TNF-? from M1-M? and IL-10 from M2-M?, as well as chemotactic chemokines from polarized macrophages. PMID:25047849

Holden, James A; Attard, Troy J; Laughton, Katrina M; Mansell, Ashley; O'Brien-Simpson, Neil M; Reynolds, Eric C

2014-10-01

323

Synthesis and biological evaluation of novel 2,4-disubstituted quinazoline analogues as GPR119 agonists.  

PubMed

GPR119 agonist has emerged as a promising target for the treatment of type 2 diabetes. A series of novel 2,4-disubstituted quinazoline analogues was prepared and evaluated their agonistic activity against human GPR119. The analogues bearing azabicyclic amine substituents (12a, 12c and 12g) exhibited better EC(50) values than that of OEA though they appeared to be partial agonists. PMID:23357035

Pham, Tuan-Anh N; Yang, Zunhua; Fang, Yuanying; Luo, Jun; Lee, Jongkook; Park, Haeil

2013-03-01

324

Modification of agonist binding moiety in hybrid derivative 5/7-{[2-(4-aryl-piperazin-1-yl)-ethyl]-propyl-amino}-5,6,7,8-tetrahydro-naphthalen-1-ol/-2-amino versions: Impact on functional activity and selectivity for dopamine D2/D3 receptors  

PubMed Central

The goal of the present study was to explore, in our previously developed hybrid template, the effect of introduction of additional heterocyclic rings (mimicking catechol hydroxyl groups as bioisosteric replacement) on selectivity and affinity for the D3 versus D2 receptor. In addition, we wanted to explore the effect of derivatization of functional groups of the agonist binding moiety in compounds developed by us earlier from the hybrid template. Binding affinity (Ki) of the new compounds was measured with tritiated spiperone as the radioligand and HEK-293 cells expressing either D2 or D3 receptors. Functional activity of selected compounds was assessed in the GTP?S binding assay. In the imidazole series, compound 10a exhibited the highest D3 affinity whereas the indole derivative 13 exhibited similar high D3 affinity. Functionalization of the amino group in agonist (+)-9d with different sulfonamides derivatives improved the D3 affinity significantly with (+)-14f exhibiting the highest affinity. However, functionalization of the hydroxyl and amino groups of 15 and (+)-9d, known agonist and partial agonist, to sulfonate ester and amide in general modulated the affinity. In both cases loss of agonist potency resulted from such derivatization. PMID:23623679

Gopishetty, Bhaskar; Zhang, Suhong; Kharkar, Prashant S.; Antonio, Tamara; Reith, Maarten; Dutta, Aloke K.

2013-01-01

325

Dopamine agonists and Othello's syndrome  

PubMed Central

Background Othello's syndrome (OS) is a delusion of infidelity. We describe seven cases of OS in Parkinson's disease (iPD) patients using dopamine agonists. Methods We searched the Mayo Clinic Medical Records System to identify all patients with OS. Clinical data abstracted include sex, age of onset of iPD, age of onset of OS, medications, effect of discontinuing the dopamine agonist, neuroimaging, and comorbidities. Results Seven non-demented iPD patients with dopamine agonist implementation time locked to the development and resolution of OS are reported. The average age of iPD onset was 46.6 years (Standard deviation: 5.0 years), and OS onset was 53.7 years (7.1 years). All seven patients had significant marital conflict as a result of the delusions. Conclusions OS can be associated with dopamine agonist use and can lead to serious consequences. Dopamine agonist cessation eliminates the delusion of infidelity and should be the first treatment option. PMID:20829092

Graff-Radford, Jonathan; Ahlskog, J Eric.; Bower, James H.; Josephs, Keith A.

2014-01-01

326

Honokiol: A non-adipogenic PPAR? agonist from nature?  

PubMed Central

Background Peroxisome proliferator-activated receptor gamma (PPAR?) agonists are clinically used to counteract hyperglycemia. However, so far experienced unwanted side effects, such as weight gain, promote the search for new PPAR? activators. Methods We used a combination of in silico, in vitro, cell-based and in vivo models to identify and validate natural products as promising leads for partial novel PPAR? agonists. Results The natural product honokiol from the traditional Chinese herbal drug Magnolia bark was in silico predicted to bind into the PPAR? ligand binding pocket as dimer. Honokiol indeed directly bound to purified PPAR? ligand-binding domain (LBD) and acted as partial agonist in a PPAR?-mediated luciferase reporter assay. Honokiol was then directly compared to the clinically used full agonist pioglitazone with regard to stimulation of glucose uptake in adipocytes as well as adipogenic differentiation in 3T3-L1 pre-adipocytes and mouse embryonic fibroblasts. While honokiol stimulated basal glucose uptake to a similar extent as pioglitazone, it did not induce adipogenesis in contrast to pioglitazone. In diabetic KKAy mice oral application of honokiol prevented hyperglycemia and suppressed weight gain. Conclusion We identified honokiol as a partial non-adipogenic PPAR? agonist in vitro which prevented hyperglycemia and weight gain in vivo. General significance This observed activity profile suggests honokiol as promising new pharmaceutical lead or dietary supplement to combat metabolic disease, and provides a molecular explanation for the use of Magnolia in traditional medicine. PMID:23811337

Atanasov, Atanas G.; Wang, Jian N.; Gu, Shi P.; Bu, Jing; Kramer, Matthias P.; Baumgartner, Lisa; Fakhrudin, Nanang; Ladurner, Angela; Malainer, Clemens; Vuorinen, Anna; Noha, Stefan M.; Schwaiger, Stefan; Rollinger, Judith M.; Schuster, Daniela; Stuppner, Hermann; Dirsch, Verena M.; Heiss, Elke H.

2013-01-01

327

Two distinct classes of novel pyrazolinecarboxamides as potent cannabinoid CB1 receptor agonists.  

PubMed

The synthesis and SAR of 3-alkyl-4-aryl-4,5-dihydropyrazole-1-carboxamides 1-23 and 1-alkyl-5-aryl-4,5-dihydropyrazole-3-carboxamides 24-27 as two novel cannabinoid CB(1) receptor agonist classes were described. The target compounds elicited high affinities to the CB(1) as well as the CB(2) receptor and were found to act as CB(1) receptor agonists. The key compound 19 elicited potent CB(1) agonistic and CB(2) inverse agonistic properties in vitro and showed in vivo activity in a rodent model for multiple sclerosis after oral administration. PMID:20688519

Lange, Jos H M; Attali, Amos; van der Neut, Martina A W; Wals, Henri C; Mulder, Arie; Zilaout, Hicham; Duursma, Ate; van Aken, Hans H M; van Vliet, Bernard J

2010-09-01

328

Species variability in platelet aggregation response to different agonists.  

PubMed

Conflicting data on platelet function in animal species are reported in the literature. In this study, the response of buffalo, horse, pig and sheep platelets to different agonists was assessed. Blood samples were collected from the jugular vein of six healthy subjects of each species and platelet-rich plasma was obtained by centrifugation. Platelet aggregation responses to increasing doses of adenosine 5'-diphosphate (ADP), arachidonic acid, collagen, platelet activating factor (PAF) and ristocetin were measured by a turbidimetric method. Horse platelets were the most responsive to ADP, collagen and PAF, whereas sheep platelets were the most responsive to ristocetin. The response to arachidonic acid varied least between species. PAF was the most effective agonist, inducing a maximum aggregation response at a concentration of 1 micro M for platelets of each species. Conversely, concentrations of ristocetin higher than 1mg/ml induced a maximum aggregation response only with sheep and horse platelets. The different responses of platelets from the four animal species to various agonists may reflect either (1). structural differences (including composition of the platelet membrane and presence of specific agonist receptors), or (2). activation of distinct signalling pathways by the agonist. PMID:12354523

Pelagalli, A; Lombardi, P; d'Angelo, D; Della Morte, R; Avallone, L; Staiano, N

2002-01-01

329

Partial Agonist, Telmisartan, Maintains PPAR? Serine 112 Phosphorylation, and Does Not Affect Osteoblast Differentiation and Bone Mass  

PubMed Central

Peroxisome proliferator activated receptor gamma (PPAR?) controls both glucose metabolism and an allocation of marrow mesenchymal stem cells (MSCs) toward osteoblast and adipocyte lineages. Its activity is determined by interaction with a ligand which directs posttranscriptional modifications of PPAR? protein including dephosphorylation of Ser112 and Ser273, which results in acquiring of pro-adipocytic and insulin-sensitizing activities, respectively. PPAR? full agonist TZD rosiglitazone (ROSI) decreases phosphorylation of both Ser112 and Ser273 and its prolonged use causes bone loss in part due to diversion of MSCs differentiation from osteoblastic toward adipocytic lineage. Telmisartan (TEL), an anti-hypertensive drug from the class of angiotensin receptor blockers, also acts as a partial PPAR? agonist with insulin-sensitizing and a weak pro-adipocytic activity. TEL decreased S273pPPAR? and did not affect S112pPPAR? levels in a model of marrow MSC differentiation, U-33/?2 cells. In contrast to ROSI, TEL did not affect osteoblast phenotype and actively blocked ROSI-induced anti-osteoblastic activity and dephosphorylation of S112pPPAR?. The effect of TEL on bone was tested side-by-side with ROSI. In contrast to ROSI, TEL administration did not affect bone mass and bone biomechanical properties measured by micro-indentation method and did not induce fat accumulation in bone, and it partially protected from ROSI-induced bone loss. In addition, TEL induced “browning” of epididymal white adipose tissue marked by increased expression of UCP1, FoxC2, Wnt10b and IGFBP2 and increased overall energy expenditure. These studies point to the complexity of mechanisms by which PPAR? acquires anti-osteoblastic and pro-adipocytic activities and suggest an importance of Ser112 phosphorylation status as being a part of the mechanism regulating this process. These studies showed that TEL acts as a full PPAR? agonist for insulin-sensitizing activity and as a partial agonist/partial antagonist for pro-adipocytic and anti-osteoblastic activities. They also suggest a relationship between PPAR? fat “browning” activity and a lack of anti-osteoblastic activity. PMID:24810249

Kolli, Vipula; Stechschulte, Lance A.; Dowling, Abigail R.; Rahman, Sima; Czernik, Piotr J.; Lecka-Czernik, Beata

2014-01-01

330

Partial agonist, telmisartan, maintains PPAR? serine 112 phosphorylation, and does not affect osteoblast differentiation and bone mass.  

PubMed

Peroxisome proliferator activated receptor gamma (PPAR?) controls both glucose metabolism and an allocation of marrow mesenchymal stem cells (MSCs) toward osteoblast and adipocyte lineages. Its activity is determined by interaction with a ligand which directs posttranscriptional modifications of PPAR? protein including dephosphorylation of Ser112 and Ser273, which results in acquiring of pro-adipocytic and insulin-sensitizing activities, respectively. PPAR? full agonist TZD rosiglitazone (ROSI) decreases phosphorylation of both Ser112 and Ser273 and its prolonged use causes bone loss in part due to diversion of MSCs differentiation from osteoblastic toward adipocytic lineage. Telmisartan (TEL), an anti-hypertensive drug from the class of angiotensin receptor blockers, also acts as a partial PPAR? agonist with insulin-sensitizing and a weak pro-adipocytic activity. TEL decreased S273pPPAR? and did not affect S112pPPAR? levels in a model of marrow MSC differentiation, U-33/?2 cells. In contrast to ROSI, TEL did not affect osteoblast phenotype and actively blocked ROSI-induced anti-osteoblastic activity and dephosphorylation of S112pPPAR?. The effect of TEL on bone was tested side-by-side with ROSI. In contrast to ROSI, TEL administration did not affect bone mass and bone biomechanical properties measured by micro-indentation method and did not induce fat accumulation in bone, and it partially protected from ROSI-induced bone loss. In addition, TEL induced "browning" of epididymal white adipose tissue marked by increased expression of UCP1, FoxC2, Wnt10b and IGFBP2 and increased overall energy expenditure. These studies point to the complexity of mechanisms by which PPAR? acquires anti-osteoblastic and pro-adipocytic activities and suggest an importance of Ser112 phosphorylation status as being a part of the mechanism regulating this process. These studies showed that TEL acts as a full PPAR? agonist for insulin-sensitizing activity and as a partial agonist/partial antagonist for pro-adipocytic and anti-osteoblastic activities. They also suggest a relationship between PPAR? fat "browning" activity and a lack of anti-osteoblastic activity. PMID:24810249

Kolli, Vipula; Stechschulte, Lance A; Dowling, Abigail R; Rahman, Sima; Czernik, Piotr J; Lecka-Czernik, Beata

2014-01-01

331

Modulation of trigeminal sensory neuron activity by the dual cannabinoid-vanilloid agonists anandamide, N-arachidonoyl-dopamine and arachidonyl-2-chloroethylamide  

PubMed Central

Peripheral cannabinoids have been shown to suppress nociceptive neurotransmission in a number of behavioral and neurophysiological studies. It is not known, however, whether cannabinoids exert this action through direct interactions with nociceptors in the periphery and/or if other processes are involved. To gain a better understanding of the direct actions of cannabinoid-vanilloid agonists on sensory neurons, we examined the effects of these compounds on trigeminal ganglion (TG) neurons in vitro. AEA (EC50=11.0 ?M), NADA (EC50=857 nM) and arachidonyl-2-chloroethylamide ACEA (EC50=14.0 ?M) each evoked calcitonin gene-related peptide (CGRP) release from TG neurons. The TRPV1 antagonists iodo-resiniferatoxin (I-RTX) and capsazepine (CPZ) each obtunded AEA-, NADA-, ACEA- and capsaicin (CAP)-evoked CGRP release with individually equivalent IC50's for each of the compounds (I-RTX IC50 range=2.6–4.0 nM; CPZ IC50 range=523–1140 ?M). The pro-inflammatory mediator prostaglandin E2 significantly increased the maximal effect of AEA-evoked CGRP release without altering the EC50. AEA, ACEA and CAP stimulated cAMP accumulation in TG neurons in a calcium- and TRPV1-dependent fashion. Moreover, the protein kinase inhibitor staurosporine significantly inhibited AEA- and CAP-evoked CGRP release. The pungency of AEA, NADA, ACEA and CAP in the rat eye-wipe assay was also assessed. Interestingly, when applied intraocularly, NADA or CAP each produced nocifensive responses, while AEA or ACEA did not. Finally, the potential inhibitory effects of these cannabinoids on TG nociceptors were evaluated. Neither AEA nor ACEA decreased CAP-evoked CGRP release. Furthermore, neither of the cannabinoid receptor type 1 antagonists SR141716A nor AM251 had any impact on either basal or CAP-evoked CGRP release. AEA also did not inhibit 50 mM K+-evoked CGRP release and did not influence bradykinin-stimulated inositol phosphate accumulation. We conclude that the major action of AEA, NADA and ACEA on TG neurons is excitatory, while, of these, only NADA is pungent. These findings are discussed in relation to our current understanding of interactions between the cannabinoid and vanilloid systems and nociceptive processing in the periphery. PMID:15006899

Price, Theodore J; Patwardhan, Amol; Akopian, Armen N; Hargreaves, Kenneth M; Flores, Christopher M

2004-01-01

332

Modulation of trigeminal sensory neuron activity by the dual cannabinoid-vanilloid agonists anandamide, N-arachidonoyl-dopamine and arachidonyl-2-chloroethylamide.  

PubMed

1. Peripheral cannabinoids have been shown to suppress nociceptive neurotransmission in a number of behavioral and neurophysiological studies. It is not known, however, whether cannabinoids exert this action through direct interactions with nociceptors in the periphery and/or if other processes are involved. To gain a better understanding of the direct actions of cannabinoid-vanilloid agonists on sensory neurons, we examined the effects of these compounds on trigeminal ganglion (TG) neurons in vitro. 2. AEA (EC(50)=11.0 microM), NADA (EC(50)=857 nM) and arachidonyl-2-chloroethylamide ACEA (EC(50)=14.0 microM) each evoked calcitonin gene-related peptide (CGRP) release from TG neurons. The TRPV1 antagonists iodo-resiniferatoxin (I-RTX) and capsazepine (CPZ) each obtunded AEA-, NADA-, ACEA- and capsaicin (CAP)-evoked CGRP release with individually equivalent IC(50)'s for each of the compounds (I-RTX IC(50) range=2.6-4.0 nM; CPZ IC(50) range=523-1140 microM). 3. The pro-inflammatory mediator prostaglandin E(2) significantly increased the maximal effect of AEA-evoked CGRP release without altering the EC(50). AEA, ACEA and CAP stimulated cAMP accumulation in TG neurons in a calcium- and TRPV1-dependent fashion. Moreover, the protein kinase inhibitor staurosporine significantly inhibited AEA- and CAP-evoked CGRP release. 4. The pungency of AEA, NADA, ACEA and CAP in the rat eye-wipe assay was also assessed. Interestingly, when applied intraocularly, NADA or CAP each produced nocifensive responses, while AEA or ACEA did not. 5. Finally, the potential inhibitory effects of these cannabinoids on TG nociceptors were evaluated. Neither AEA nor ACEA decreased CAP-evoked CGRP release. Furthermore, neither of the cannabinoid receptor type 1 antagonists SR141716A nor AM251 had any impact on either basal or CAP-evoked CGRP release. AEA also did not inhibit 50 mM K(+)-evoked CGRP release and did not influence bradykinin-stimulated inositol phosphate accumulation. 6. We conclude that the major action of AEA, NADA and ACEA on TG neurons is excitatory, while, of these, only NADA is pungent. These findings are discussed in relation to our current understanding of interactions between the cannabinoid and vanilloid systems and nociceptive processing in the periphery. PMID:15006899

Price, Theodore J; Patwardhan, Amol; Akopian, Armen N; Hargreaves, Kenneth M; Flores, Christopher M

2004-04-01

333

PPAR? agonists inhibit TGF-?-PKA signaling in glomerulosclerosis  

PubMed Central

Aim: To study the probable mechanisms of the anti-glomerulosclerosis effects induced by peroxisome proliferator-activated receptor gamma (PPAR?) agonists in rat intraglomerular mesangial cells (MCs). Methods: Cells were transfected with the pTAL-PPRE-tk-Luc+ plasmid and then treated with different concentrations of PPAR? agonist, either troglitazone or telmisartan, for the indicated times. Promega luciferase assays were subsequently used for the detection of PPAR? activation. Protein expression levels were assessed by Western blot, and PepTag® assays were used for the non-radioactive detection of protein kinase A (PKA) activity. The deposition of ?-smooth muscle actin (?-SMA) and p-cyclic AMP responsive element binding protein (pCREB) were analyzed by confocal laser scanning. Results: Both troglitazone and telmisartan remarkably inhibit the PKA activation and pCREB expression that is stimulated by TGF-?. The PPAR? agonists also inhibited ?-SMA and collagen IV protein expression by blocking PKA activation. Conclusion: PPAR? ligands effectively suppress the activation of MCs and the accumulation of collagen IV stimulated by TGF-? in vitro. The renal protection provided by PPAR? agonists is partly mediated via their blockade of TGF-?/PKA signaling. PMID:20037602

Zou, Rong; Xu, Gang; Liu, Xiao-cheng; Han, Min; Jiang, Jing-jing; Huang, Qian; He, Yong; Yao, Ying

2010-01-01

334

Dominance relations and agonistic behaviour of Tundra Swans ( Cygnus columbianus columbianus ) during fall and spring migration  

Microsoft Academic Search

Social interactions and agonistic activities of Tundra Swans (Cygnus columbianus columbianus ) were docu- mented at Long Point, Ontario, to determine (i) dominance relations among social groups and (ii) the frequency and in- tensity of agonistic acts by swans. Families were involved in one-third as many interactions as were nonfamily groups. Nonfamily groups initiated interactions with other nonfamily groups more

Shannon S. Badzinski

2003-01-01

335

Discovery of tertiary aminoacids as dual PPARalpha/gamma agonists-I.  

PubMed

A novel series of potent dual agonists of PPARalpha and PPARgamma, the alkoxybenzylglycines, was identified and explored using a solution-phase library approach. The synthesis and structure-activity relationships of this series of dual PPARalpha/gamma agonists are described. PMID:17292606

Devasthale, Pratik V; Chen, Sean; Jeon, Yoon; Qu, Fucheng; Ryono, Denis E; Wang, Wei; Zhang, Hao; Cheng, Lin; Farrelly, Dennis; Golla, Rajasree; Grover, Gary; Ma, Zhengping; Moore, Lisa; Seethala, Ramakrishna; Sun, Wei; Doweyko, Arthur M; Chandrasena, Gamini; Sleph, Paul; Hariharan, Narayanan; Cheng, Peter T W

2007-04-15

336

Parallel changes in agonistic and non-agonistic behaviors during dominance hierarchy formation in crayfish  

Microsoft Academic Search

Agonistic and non-agonistic behaviors were studied before, during, and after the formation of social status in crayfish. Differences in the expression of a non-agonistic behavior by dominant and subordinate crayfish developed in parallel with the differences in agonistic behaviors that indicate the animals' social status. An increase in burrowing behavior marked the ascendancy of the dominant animal, while an immediate

J. Herberholz; M. M. Sen; D. H. Edwards

2003-01-01

337

Different hip rotations influence hip abductor muscles activity during isometric side-lying hip abduction in subjects with gluteus medius weakness.  

PubMed

The purpose of this study was to establish the effects of different hip rotations during isometric side-lying hip abduction (SHA) in subjects with gluteus medius (Gmed) weakness by investigating the electromyographic (EMG) amplitude of the Gmed, tensor fasciae latae (TFL) activity, and gluteus maximus (Gmax), and the activity ratio of the Gmed/TFL, Gmax/TFL, and Gmed/Gmax. Nineteen subjects with Gmed weakness were recruited for this study. Subjects performed three isometric hip abductions: frontal SHA with neutral hips (SHA-N), frontal SHA with hip medial rotation (SHA-MR), and frontal SHA with hip lateral rotation (SHA-LR). Surface EMG amplitude was measured to collect the EMG data from the Gmed, TFL, and Gmax. A one-way repeated-measures analysis of variance was used to determine the statistical significance of the Gmed, TFL, and Gmax EMG activity and the Gmed/TFL, Gmax/TFL, and Gmed/Gmax EMG activity ratios. Gmed EMG activity was significantly greater in SHA-MR than in SHA-N. TFL EMG activity was significantly greater in SHA-LR than in SHA-N. The Gmed/TFL and Gmed/Gmax EMG activity ratios were also significantly greater in SHA-MR than in SHA-N or SHA-LR. The results of this study suggest that SHA-MR can be used as an effective method to increase Gmed activation and to decrease TFL activity during SHA exercises. PMID:24560168

Lee, Ji-Hyun; Cynn, Heon-Seock; Kwon, Oh-Yun; Yi, Chung-Hwi; Yoon, Tae-Lim; Choi, Woo-Jeong; Choi, Sil-Ah

2014-04-01

338

The role of activation of the 5-HT1A receptor and adenylate cyclase in the antidepressant-like effect of YL-0919, a dual 5-HT1A agonist and selective serotonin reuptake inhibitor.  

PubMed

This study aimed to explore the possible mechanisms underlying the antidepressant-like effect of YL-0919, a novel antidepressant candidate with dual activity as a 5-HT1A receptor agonist and a selective serotonin reuptake inhibitor. The animal models commonly used to evaluate potential antidepressants, i.e., tail suspension (TST) in mice and forced swimming test (FST) in mice were used to evaluate the antidepressant effect of YL-0919. The activity of adenylate cyclase (AC) on the synaptic membrane was determined by the homogeneous time-resolved fluorescence resonance energy transfer (TR-FRET) immunoassay. The results indicated that YL-0919 (1.25-2.5mg/kg, i.g.) significantly decreased the immobility time in both the tail suspension test and the forced swim test in a dose-dependent manner, demonstrating the antidepressant-like effect of YL-0919. Furthermore, this effect was completely antagonized by the co-administration of WAY-100635 (0.3mg/kg, s.c.), a 5-HT1A selective antagonist. YL-0919 (10(-9)-10(-5)mol/L) was also shown to activate AC in vitro in a dose-dependent manner in synaptic membranes extracted from the rat prefrontal cortex, and this effect (10(-7)-10(-5)mol/L) was antagonized by WAY-100635 (10(-7)mol/L). Finally, the antidepressant-like effect of YL-0919 (2.5mg/kg, i.g.) was also blocked by the co-administration of H-89 (3?g/site, i.c.v.), a protein kinase A (PKA) selective inhibitor. These results indicate that the activation of 5-HT1A receptors and the subsequent activation of the AC-cAMP-PKA signaling pathway in the frontal cortex play a critical role in the antidepressant-like effect of YL-0919. PMID:25220701

Qin, Juan-Juan; Chen, Hong-Xia; Zhao, Nan; Yuan, Li; Zhang, You-Zhi; Yang, Ri-Fang; Zhang, Li-Ming; Li, Yun-Feng

2014-10-17

339

Surface ozone and NOx trends observed over Kannur, a South Indian coastal location of weak industrial activities  

NASA Astrophysics Data System (ADS)

South India is a peninsular region surrounded by the three belts of Arabian Sea, Bay of Bengal and Indian Ocean. Usually, coastal regions experience relatively high air quality compared to that of the interior land masses owing to the abundance of OH over ocean surface which acts as detergent in the atmosphere. Kannur (11.9 N, 75.4E, 5 m AMSL) is a coastal location along the Arabian Sea which is located in the northern district of Kerala State with fairly low industrial activities. A continuous observation of surface ozone (O3), NOx and OX (NO2+ O3) which has been initiated at this coastal site since 2009 reveals the enhancement in the concentrations of these trace species quite significantly. It is observed that surface O3 mixing ratio is increased at a rate of 1.51 ± 0.5 ppbv/year during the four year period from 2009 at Kannur. The enhancement rate in the mixing ratios of NOx is 1.01 ± 0.4 ppbv/year and OX is 1.49±0.42 ppbv/year respectively. The increase of O3 may be attributed due to the increase in methane and non-methane organic emissions from the wet lands and vehicles may enhance O3 production and fairly low rate of change of NO concentration at this site. This paper describes the rate of changes of O3, NOx and OX during the period of observation in detail. Likewise, the increase in nighttime concentrations of O3 and PM10 observed during the festival occasions in the summer month of April in all years is explained. Being a weak industrialized location, the main source of pollution is by vehicular emissions and the increase in these trace gases in the context of rapid enhancement in the number of vehicles is well correlated. These results may be helpful for improving government policies to control the photochemical formation of secondary air pollutants in the rural coastal sites that has a significant influence on the onset of monsoon and the outcome of this study have significant relevance for gradual transformation of pristine locations into polluted sites.

Kumar, Satheesh Mk; T, Nishanth; M, Praseeed K.

340

A Point Mutation That Confers Constitutive Activity to CXCR4 Reveals That T140 Is an Inverse Agonist and That AMD3100 and  

E-print Network

A Point Mutation That Confers Constitutive Activity to CXCR4 Reveals That T140 Is an Inverse University, Princeton, New Jersey 08544 CXCR4 is a G protein-coupled receptor for stromal- derived factor 1, and human immunodeficiency virus type-1 infec- tion. To elucidate the mechanism for CXCR4 activation

Tian, Weidong

341

Calpastatin domain L is a partial agonist of the calmodulin-binding site for channel activation in Cav1.2 Ca2+  

E-print Network

)-99-275-5522, E-mail: kame@m.kufm.kagoshima-u.ac.jp Cav1.2 Ca2+ channel activity diminishes in inside-out patchesM) recover channel activity from the run-down in guinea-pig cardiac myocytes. Because the potency of the CSL

Turner, Ray

342

PPAR{alpha} agonist fenofibrate protects the kidney from hypertensive injury in spontaneously hypertensive rats via inhibition of oxidative stress and MAPK activity  

SciTech Connect

Oxidative stress has been shown to play an important role in the development of hypertensive renal injury. Peroxisome proliferator-activated receptors {alpha} (PPAR{alpha}) has antioxidant effect. In this study, we demonstrated that fenofibrate significantly reduced proteinuria, inflammatory cell recruitment and extracellular matrix (ECM) proteins deposition in the kidney of SHRs without apparent effect on blood pressure. To investigate the mechanisms involved, we found that fenofibrate treatment markedly reduced oxidative stress accompanied by reduced activity of renal NAD(P)H oxidase, increased activity of Cu/Zn SOD, and decreased phosphorylation of p38MAPK and JNK in the kidney of SHRs. Taken together, fenofibrate treatment can protect against hypertensive renal injury without affecting blood pressure by inhibiting inflammation and fibrosis via suppression of oxidative stress and MAPK activity.

Hou, Xiaoyang [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, 250012 Jinan, Shandong (China) [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, 250012 Jinan, Shandong (China); Division of Cardiothoracic Surgery, The Michael E. DeBakey Department of Surgery, Baylor College of Medicine, BCM 390, One Baylor Plaza, Houston, TX 77030 (United States); Shen, Ying H. [Division of Cardiothoracic Surgery, The Michael E. DeBakey Department of Surgery, Baylor College of Medicine, BCM 390, One Baylor Plaza, Houston, TX 77030 (United States)] [Division of Cardiothoracic Surgery, The Michael E. DeBakey Department of Surgery, Baylor College of Medicine, BCM 390, One Baylor Plaza, Houston, TX 77030 (United States); Li, Chuanbao; Wang, Fei; Zhang, Cheng [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, 250012 Jinan, Shandong (China)] [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, 250012 Jinan, Shandong (China); Bu, Peili, E-mail: peilibu6320@hotmail.com [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, 250012 Jinan, Shandong (China)] [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, 250012 Jinan, Shandong (China); Zhang, Yun [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, 250012 Jinan, Shandong (China)] [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, 250012 Jinan, Shandong (China)

2010-04-09

343

Peroxisome proliferator-activated receptor alpha (PPARalpha) agonists down-regulate alpha2-macroglobulin expression by a PPARalpha-dependent mechanism.  

EPA Science Inventory

Peroxisome proliferator-activated receptor alpha (PPARa) regulates transcription of genes involved both in lipid and glucose metabolism as well as inflammation. Fibrates are PPARa ligands used to normalize lipid and glucose parameters and exert anti-inflammatory effects. Fibrates...

344

Investigating Activity Patterns In Prehispanic Plazas: Weak Acid-Extraction ICP-AES Analysis of Anthrosols at Classic Period El Coyote, Northwestern Honduras  

Microsoft Academic Search

Weak acid-extraction ICP-AES analysis was performed to obtain multi-elemental charac- terizations of anthropogenic sediments from plaza spaces that no longer contain artefacts and adjacent trash deposits at the prehispanic site of El Coyote in northwestern Honduras. Multivariate quantitative assessments of the anthrosol chemical data, along with associated inventories of midden materials, are examined to derive signatures for activity areas and

E. C. Wells

2004-01-01

345

Pyrrolo- and pyridomorphinans: non-selective opioid antagonists and delta opioid agonists/mu opioid partial agonists.  

PubMed

Opioid ligands have found use in a number of therapeutic areas, including for the treatment of pain and opiate addiction (using agonists) and alcohol addiction (using antagonists such as naltrexone and nalmefene). The reaction of imines, derived from the opioid ligands oxymorphone and naltrexone, with Michael acceptors leads to pyridomorphinans with structures similar to known pyrrolo- and indolomorphinans. One of the synthesized compounds, 5e, derived from oxymorphone had substantial agonist activity at delta opioid receptors but not at mu and/or kappa opioid receptors and in that sense profiled as a selective delta opioid receptor agonist. The pyridomorphinans derived from naltrexone and naloxone were all found to be non-selective potent antagonists and as such could have utility as treatments for alcohol abuse. PMID:24973818

Kumar, V; Clark, M J; Traynor, J R; Lewis, J W; Husbands, S M

2014-08-01

346

AMP-activated kinase relaxes agonist induced contractions in the mouse aorta via effects on PKC signaling and inhibits NO-induced relaxation.  

PubMed

Adenosine monophosphate activated kinase (AMPK), a regulator of cellular metabolism, has been shown to relax arterial smooth muscle via endothelium-dependent and independent mechanisms. We have examined the role of AMPK in different smooth muscles using the activating compound, 5-amino-4-imidazolecarboxamide riboside-1-?-d-ribofuranoside (AICAR). Isolated preparations of mouse aorta, saphenous artery, ileum and urinary bladder were compared. AICAR produced a reversible dose-dependent relaxation in aortic rings pre-incubated with AICAR and activated with phenylephrine. Less prominent relaxation was noted in the other tissues. This difference in sensitivity to AICAR was not due to differences in the expression levels of AMPK ?1 mRNA. In the aorta, AICAR had a greater effect on contractions induced by phenylephrine, compared to high-K(+) induced contractions. Contractions of the aorta in response to the protein kinase C activator PDBu were prominently inhibited by AICAR. The AICAR relaxation observed in the aorta was not prevented by the NOS inhibitor L-NAME, Indomethacin or endothelium removal. Nitric oxide (NO) mediated relaxations in aortic preparations induced by acetylcholine or sodium nitroprusside (SNP) were attenuated by AICAR. In conclusion, AMPK induced relaxation of smooth muscle is tissue-dependent and most prominent in large elastic arteries. The smooth muscle relaxation is NO-independent and occurs downstream of PKC activation and is associated with attenuated relaxant responses to NO. PMID:22921370

Davis, Benjamin; Rahman, Awahan; Arner, Anders

2012-11-15

347

Design and synthesis of N-[(4-methoxyphenoxy)carbonyl]-N-[[4-[2-(5- methyl-2-phenyl-4-oxazolyl)ethoxy]phenyl]methyl]glycine [Muraglitazar/BMS-298585], a novel peroxisome proliferator-activated receptor alpha/gamma dual agonist with efficacious glucose and lipid-lowering activities.  

PubMed

Muraglitazar/BMS-298585 (2) has been identified as a non-thiazolidinedione PPAR alpha/gamma dual agonist that shows potent activity in vitro at human PPARalpha (EC(50) = 320 nM) and PPARgamma(EC(50) = 110 nM). Compound 2 shows excellent efficacy for lowering glucose, insulin, triglycerides, and free fatty acids in genetically obese, severely diabetic db/db mice and has a favorable ADME profile. Compound 2 is currently in clinical development for the treatment of type 2 diabetes and dyslipidemia. PMID:15771468

Devasthale, Pratik V; Chen, Sean; Jeon, Yoon; Qu, Fucheng; Shao, Chunning; Wang, Wei; Zhang, Hao; Cap, Michael; Farrelly, Dennis; Golla, Rajasree; Grover, Gary; Harrity, Thomas; Ma, Zhengping; Moore, Lisa; Ren, Jimmy; Seethala, Ramakrishna; Cheng, Lin; Sleph, Paul; Sun, Wei; Tieman, Aaron; Wetterau, John R; Doweyko, Arthur; Chandrasena, Gamini; Chang, Shu Y; Humphreys, W Griffith; Sasseville, Vito G; Biller, Scott A; Ryono, Denis E; Selan, Fred; Hariharan, Narayanan; Cheng, Peter T W

2005-03-24

348

R-(-)-beta-phenyl-GABA is a full agonist at GABAB receptors in brain slices but a partial agonist in the ileum.  

PubMed

R-(-)-beta-phenyl-GABA has been compared at GABAB receptors using cortical and ileal preparations. R-(-)-beta-phenyl-GABA (EC50 = 25 microM) was a less potent full agonist than R,S-(+/-)-baclofen (EC50 = 2.5 microM), in depressing CA1 population spikes of rat hippocampal slices, and 5 times less potent in attenuating the spontaneous discharges of rat neocortex. However, R-(-)-beta-phenyl-GABA (100-400 microM) was only a weak partial agonist in the ileum. All these actions were sensitive to CGP 35348 (3-aminopropyl-(P-diethoxymethyl)-phosphinic acid) and therefore mediated by GABAB receptors. PMID:8386087

Ong, J; Kerr, D I; Doolette, D J; Duke, R K; Mewett, K N; Allen, R D; Johnston, G A

1993-03-16

349

Discovery of an Oxybenzylglycine Based Peroxisome Proliferator Activated Receptor [alpha] Selective Agonist 2-((3-((2-(4-Chlorophenyl)-5-methyloxazol-4-yl)methoxy)benzyl)(methoxycarbonyl)amino)acetic Acid (BMS-687453)  

SciTech Connect

An 1,3-oxybenzylglycine based compound 2 (BMS-687453) was discovered to be a potent and selective peroxisome proliferator activated receptor (PPAR) {alpha} agonist, with an EC{sub 50} of 10 nM for human PPAR{alpha} and 410-fold selectivity vs human PPAR{gamma} in PPAR-GAL4 transactivation assays. Similar potencies and selectivity were also observed in the full length receptor co-transfection assays. Compound 2 has negligible cross-reactivity against a panel of human nuclear hormone receptors including PPAR{delta}. Compound 2 demonstrated an excellent pharmacological and safety profile in preclinical studies and thus was chosen as a development candidate for the treatment of atherosclerosis and dyslipidemia. The X-ray cocrystal structures of the early lead compound 12 and compound 2 in complex with PPAR{alpha} ligand binding domain (LBD) were determined. The role of the crystal structure of compound 12 with PPAR{alpha} in the development of the SAR that ultimately resulted in the discovery of compound 2 is discussed.

Li, Jun; Kennedy, Lawrence J.; Shi, Yan; Tao, Shiwei; Ye, Xiang-Yang; Chen, Stephanie Y.; Wang, Ying; Hernndez, Andrs S.; Wang, Wei; Devasthale, Pratik V.; Chen, Sean; Lai, Zhi; Zhang, Hao; Wu, Shung; Smirk, Rebecca A.; Bolton, Scott A.; Ryono, Denis E.; Zhang, Huiping; Lim, Ngiap-Kie; Chen, Bang-Chi; Locke, Kenneth T.; O’ Malley, Kevin M.; Zhang, Litao; Srivastava, Rai Ajit; Miao, Bowman; Meyers, Daniel S.; Monshizadegan, Hossain; Search, Debra; Grimm, Denise; Zhang, Rongan; Harrity, Thomas; Kunselman, Lori K.; Cap, Michael; Kadiyala, Pathanjali; Hosagrahara, Vinayak; Zhang, Lisa; Xu, Carrie; Li, Yi-Xin; Muckelbauer, Jodi K.; Chang, Chiehying; An, Yongmi; Krystek, Stanley R.; Blanar, Michael A.; Zahler, Robert; Mukherjee, Ranjan; Cheng, Peter T.W.; Tino, Joseph A. (BMS)

2010-04-12

350

A Novel Non-agonist Peroxisome Proliferator-activated Receptor ? (PPAR?) Ligand UHC1 Blocks PPAR? Phosphorylation by Cyclin-dependent Kinase 5 (CDK5) and Improves Insulin Sensitivity.  

PubMed

Thiazolidinedione class of anti-diabetic drugs which are known as peroxisome proliferator-activated receptor ? (PPAR?) ligands have been used to treat metabolic disorders, but thiazolidinediones can also cause several severe side effects, including congestive heart failure, fluid retention, and weight gain. In this study, we describe a novel synthetic PPAR? ligand UNIST HYUNDAI Compound 1 (UHC1) that binds tightly to PPAR? without the classical agonism and which blocks cyclin-dependent kinase 5 (CDK5)-mediated PPAR? phosphorylation. We modified the non-agonist PPAR? ligand SR1664 chemically to improve its solubility and then developed a novel PPAR? ligand, UHC1. According to our docking simulation, UHC1 occupied the ligand-binding site of PPAR? with a higher docking score than SR1664. In addition, UHC1 more potently blocked CDK5-mediated PPAR? phosphorylation at Ser-273. Surprisingly, UHC1 treatment effectively ameliorated the inflammatory response both in vitro and in high-fat diet-fed mice. Furthermore, UHC1 treatment dramatically improved insulin sensitivity in high-fat diet-fed mice without causing fluid retention and weight gain. Taken together, compared with SR1664, UHC1 exhibited greater beneficial effects on glucose and lipid metabolism by blocking CDK5-mediated PPAR? phosphorylation, and these data indicate that UHC1 could be a novel therapeutic agent for use in type 2 diabetes and related metabolic disorders. PMID:25100724

Choi, Sun-Sil; Kim, Eun Sun; Koh, Minseob; Lee, Soo-Jin; Lim, Donghyun; Yang, Yong Ryoul; Jang, Hyun-Jun; Seo, Kyung-Ah; Min, Sang-Hyun; Lee, In Hee; Park, Seung Bum; Suh, Pann-Ghill; Choi, Jang Hyun

2014-09-19

351

Discovery of Highly Potent and Selective ?4?2-Nicotinic Acetylcholine Receptor (nAChR) Partial Agonists Containing an Isoxazolylpyridine Ether Scaffold that Demonstrate Antidepressant-like Activity. Part II  

PubMed Central

In our continued efforts to develop ?4?2-nicotinic acetylcholine receptor (nAChR) partial agonists as novel antidepressants having a unique mechanism of action, structure activity relationship (SAR) exploration of certain isoxazolylpyridine ethers is presented. In particular, modifications to both the azetidine ring present in the starting structure 4 and its metabolically liable hydroxyl side chain substituent have been explored to improve compound druggability. The pharmacological characterization of all new compounds has been carried out using [3H]epibatidine binding studies together with functional assays based on 86Rb+ ion flux measurements. We found that the deletion of the metabolically liable hydroxyl group or its replacement by a fluoromethyl group not only maintained potency and selectivity, but also resulted in compounds showing antidepressant-like properties in the mouse forced swim test. These isoxazolylpyridine ethers appear to represent promising lead candidates in the design of innovative chemical tools containing reporter groups for imaging purposes and of possible therapeutics. PMID:23092294

Yu, Li-Fang; Eaton, J. Brek; Fedolak, Allison; Zhang, Han-Kun; Hanania, Taleen; Brunner, Dani; Lukas, Ronald J.; Kozikowski, Alan P.

2012-01-01

352

Mixed kappa/mu partial opioid agonists as potential treatments for cocaine dependence.  

PubMed

Cocaine use activates the dopamine reward pathway, leading to the reinforcing effects of dopamine. There is no FDA-approved medication for treating cocaine dependence. Opioid agonists and antagonists have been approved for treating opioid and alcohol dependence. Agonists that activate the ? opioid receptor increase dopamine levels in the nucleus accumbens, while ? receptor antagonists decrease dopamine levels by blocking the effects of endogenous opioid peptides. Activation of the ? opioid receptor decreases dopamine levels and leads to dysphoria. In contrast, inhibition of the ? opioid receptor decreases dopamine levels in the nucleus accumbens. Antagonists acting at the ? receptor reduce stress-mediated behaviors and anxiety. Mixed partial ?/? agonists have the potential of striking a balance between dopamine levels and attenuating relapse to cocaine. The pharmacological properties of mixed ?/? opioid receptor agonists will be discussed and results from clinical and preclinical studies will be presented. Results from studies with some of the classical benzomorphans and morphinans will be presented as they lay the foundation for structure-activity relationships. Recent results with other partial opioid agonists, including buprenorphine derivatives and the mixed ?/? peptide CJ-15,208, will be discussed. The behavioral effects of the mixed ?/? MCL-741, an aminothiazolomorphinan, in attenuating cocaine-induced locomotor activity will be presented. While not a mixed ?/? opioid, results obtained with GSK1521498, a ? receptor inverse agonist, will be discussed. Preclinical strategies and successes will lay the groundwork for the further development of mixed ?/? opioid receptor agonists to treat cocaine dependence. PMID:24484983

Bidlack, Jean M

2014-01-01

353

Are Peroxisome Proliferator-Activated Receptors Involved in Skeletal Muscle Wasting during Experimental Cancer Cachexia? Role of B2Adrenergic Agonists  

Microsoft Academic Search

Implantation of the Yoshida AH-130 ascites hepatoma to rats resulted in a decrease in muscle weight 7 days after the inoculation of the tumor. These changes were associated with increases in the mRNA content for both peroxisome prolifer- ator-activated receptor (PPAR) ; and PPARD in skeletal muscle. The increase in gene expression for these transcription factors was related to increases

Gemma Fuster; Silvia Busquets; Elisabet Ametller; Mireia Olivan; Vanessa Almendro; Cristine Fontes de Oliveira; Maite Figueras; Francisco J. Lopez-Soriano; Josep M. Argiles

2007-01-01

354

Rhamnogalacturonan II is a Toll-like receptor 4 agonist that inhibits tumor growth by activating dendritic cell-mediated CD8+ T cells  

PubMed Central

We evaluated the effectiveness of rhamnogalacturonan II (RG-II)-stimulated bone marrow-derived dendritic cells (BMDCs) vaccination on the induction of antitumor immunity in a mouse lymphoma model using EG7-lymphoma cells expressing ovalbumin (OVA). BMDCs treated with RG-II had an activated phenotype. RG-II induced interleukin (IL)-12, IL-1?, tumor necrosis factor-? (TNF-?) and interferon-? (IFN-?) production during dendritic cell (DC) maturation. BMDCs stimulated with RG-II facilitate the proliferation of CD8+ T cells. Using BMDCs from the mice deficient in Toll-like receptors (TLRs), we revealed that RG-II activity is dependent on TLR4. RG-II showed a preventive effect of immunization with OVA-pulsed BMDCs against EG7 lymphoma. These results suggested that RG-II expedites the DC-based immune response through the TLR4 signaling pathway. PMID:23392255

Park, Sung Nam; Tae Noh, Kyung; Jeong, Young-Il; Duk Jung, In; Kyu Kang, Hyun; Sun Cha, Gil; Jung Lee, Su; Keun Seo, Jong; Hwan Kang, Dae; Hwang, Tae-Ho; Kyung Lee, Eun; Kwon, Byungsuk; Park, Yeong-Min

2013-01-01

355

Agonist-Activated Glucocorticoid Receptor Inhibits Binding of Heat Shock Factor 1 to the Heat Shock Protein 70 Promoter in Vivo  

Microsoft Academic Search

We have previously shown that activation of glu- cocorticoid receptor (GR) signaling in stressed cells will cause inhibition of the heat shock re- sponse as mediated by heat shock transcription factor 1 (HSF1). In that work, a full-length human heat shock protein 70 (Hsp70) promoter was used to measure HSF1 transactivity, and the data sug- gested inhibition of HSF1 through

SUBHAGYA A. WADEKAR; DAPEI LI; EDWIN R. SANCHEZ

2003-01-01

356

In vivo priming of IL-17(+) uveitogenic T cells is enhanced by Toll ligand receptor (TLR)2 and TLR4 agonists via ?? T cell activation.  

PubMed

We investigated the in vivo priming of IL-17(+) autoreactive T cells in experimental autoimmune uveitis-prone C57BL/6 (B6) and B10RIII mice using a combination of approaches, including limiting dilution assay. High numbers of in vivo primed IL-17(+) interphotoreceptor retinoid-binding protein (IRBP)-specific T cells were found in mice immunized with a uveitogenic peptide emulsified in CFA, but not the same peptide emulsified in IFA. Both in vitro and in vivo, at least part of the effect of mycobacterial antigen in CFA could be replaced by TLR2 or TLR4 ligands. TCR-?(-/-) mice immunized with IRBP peptide in CFA generated significantly lower numbers of IL-17(+) T cells than immunized wild-type B6 mice. Administration of a small number of activated ?? T cells to TCR-?(-/-) mice significantly increased the number of IL-17(+), but not IFN-?(+), IRBP-specific T cells in these mice. ?? T cells from CFA- or IFA plus TLR ligand-treated mice were activated and injection of naïve TCR-?(-/-) mice with ?? T cells from TLR ligand-treated, but not untreated, B6 mice promoted the in vivo priming of IL-17(+) IRBP-reactive T cells. In conclusion, in vivo priming of IL-17(+) uveitogenic T cells in mice is significantly affected by TLR ligation, and is also influenced by activated ?? T cells. PMID:22301006

Zuo, Aijun; Liang, Dongchun; Shao, Hui; Born, Willi K; Kaplan, Henry J; Sun, Deming

2012-03-01

357

SUZAKU OBSERVES WEAK FLARES FROM IGR J17391-3021 REPRESENTING A COMMON LOW-ACTIVITY STATE IN THIS SUPERGIANT FAST X-RAY TRANSIENT  

SciTech Connect

We present an analysis of a 37 ks observation of the supergiant fast X-ray transient IGR J17391-3021 (= XTE J1739-302) gathered with Suzaku. The source evolved from quiescence to a low-activity level culminating in three weak flares lasting {approx}3 ks each in which the peak luminosity is only a factor of five times that of the pre-flare luminosity. The minimum observed luminosity was 1.3 x 10{sup 33} erg s{sup -1}(d/2.7 kpc){sup 2} in the 0.5-10 keV range. The weak flares are accompanied by significant changes in the spectral parameters including a column density (N{sub H} =(4.1{sup +0.4}{sub -0.5}) x 10{sup 22} cm{sup -2}) that is {approx}2-9 times the absorption measured during quiescence. Accretion of obscuring clumps of stellar wind material can explain both the small flares and the increase in N{sub H}. Placing this observation in the context of the recent Swift monitoring campaign, we find that weak-flaring episodes, or at least epochs of enhanced activity just above the quiescent level but well below the moderately bright or high-luminosity outbursts, represent more than 60% {+-} 5% of all observations in the 0.5-10 keV energy range making this the most common state in the emission behavior of IGR J17391-3021.

Bodaghee, A.; Tomsick, J. A. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720 (United States); Rodriguez, J.; Chaty, S. [Laboratoire AIM, CEA/IRFU-Universite Paris Diderot-CNRS/INSU, CEA DSM/IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette (France); Pottschmidt, K. [CRESST and NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771 (United States); Walter, R. [INTEGRAL Science Data Centre, Universite de Geneve, Chemin d'Ecogia 16, CH-1290 Versoix (Switzerland); Romano, P., E-mail: bodaghee@ssl.berkeley.edu [INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, Via U. La Malfa 153, I-90146 Palermo (Italy)

2011-01-20

358

Pharmacology and clinical potential of guanylyl cyclase C agonists in the treatment of ulcerative colitis  

PubMed Central

Agonists of the transmembrane intestinal receptor guanylyl cyclase C (GCC) have recently attracted interest as promising human therapeutics. Peptide ligands that can specifically induce GCC signaling in the intestine include endogenous hormones guanylin and uroguanylin, diarrheagenic bacterial enterotoxins (ST), and synthetic drugs linaclotide, plecanatide, and SP-333. These agonists bind to GCC at intestinal epithelial surfaces and activate the receptor’s intracellular catalytic domain, an event initiating discrete biological responses upon conversion of guanosine-5?-triphosphate to cyclic guanosine monophosphate. A principal action of GCC agonists in the colon is the promotion of mucosal homeostasis and its dependent barrier function. Herein, GCC agonists are being developed as new medications to treat inflammatory bowel diseases, pathological conditions characterized by mucosal barrier hyperpermeability, abnormal immune reactions, and chronic local inflammation. This review will present important concepts underlying the pharmacology and therapeutic utility of GCC agonists for patients with ulcerative colitis, one of the most prevalent inflammatory bowel disease disorders. PMID:23637522

Pitari, Giovanni M

2013-01-01

359

Both the Peroxisome Proliferator-Activated Receptor (PPAR) delta agonist, GW0742, and ezetimibe promote reverse cholesterol transport in mice by reducing intestinal re-absorption of HDL-derived cholesterol  

PubMed Central

PPAR? agonism increases HDL-cholesterol and has therefore the potential to stimulate macrophage-to-feces reverse cholesterol transport (RCT). To test whether PPAR? activation promotes RCT in mice, in vivo macrophage RCT was assessed using cholesterol loaded/3H-cholesterol labeled macrophages injected intraperitoneally. PPAR? agonist GW0742 (10mg/kg/day) did not change 3H -tracer plasma appearance, but increased fecal 3H-free sterols excretion by 103% (p<0.005) over 48 hours. Total free cholesterol efflux from macrophages to serum (collected from both control and GW0742 groups) was not different, although ABCA1-mediated efflux was significantly higher with GW0742. The metabolic fate of HDL labeled with 3H-cholesteryl ether or 3H-cholesteryl oleate was also measured. While 3H-cholesteryl ether tissue uptake was unchanged, the 3H-tracer recovered in fecal free sterol fraction after 3H-cholesteryl oleate injection increased by 88% with GW0742 (p<0.0005). This was associated with a lower Niemann Pick C1 like 1 (NPC1L1) mRNA expression in the small intestine (p<0.05). The same experiments in mice treated with ezetimibe, which blocks NPC1L1, showed a similar 2-fold increase in fecal free sterol excretion after labeled macrophages or HDL injection. In conclusion, PPAR? activation enhances excretion of macrophage or HDL-derived cholesterol in feces through reduced NPC1L1 expression in mice, comparable to the effect of ezetimibe. PMID:20169010

Briand, François; Naik, Snehal U; Fuki, Ilia; Millar, John S; Macphee, Colin; Walker, Max; Billheimer, Jeffrey; Rothblat, George; Rader, Daniel J

2009-01-01

360

Adenosine: A Partial Agonist of the Growth Hormone Secretagogue Receptor  

Microsoft Academic Search

The growth hormone secretagogue receptor (GHS-R) is involved in the regulation of pulsatile GH release. However, until recently, natural endogenous ligands for the receptor were unknown. We fractionated porcine hypothalamic extracts and assayed fractions for activity on HEK293 cells expressing GHS-R and aequorin. A partial agonist was isolated and identified using microspray tandem mass spectrometry as adenosine. GHS-R activation by

Roy G. Smith; Patrick R. Griffin; Yuan Xu; Alexander G. A. Smith; Ken Liu; Jimmy Calacay; Scott D. Feighner; C.-S. Pong; Denis Leong; Anna Pomés; Kang Cheng; Andrew D. Howard; James Schaeffer; Reid J. Leonard

2000-01-01

361

Effects of inhaled ? agonist and corticosteroid treatment on nuclear transcription factors in bronchial mucosa in asthma  

Microsoft Academic Search

BACKGROUNDInhaled corticosteroids and ? agonists are the most commonly used treatments in asthma and are often used together. Recent evidence suggests that many of the anti-inflammatory actions of corticosteroids are mediated by cross-talk between the activated glucocorticoid receptor (GR) and other transcription factors such as the pro-inflammatory nuclear factor kappa B (NF?B). Beta agonists can activate the transcription factor cAMP

Robert J Hancox; David A Stevens; Ian M Adcock; Peter J Barnes; D Robin Taylor

1999-01-01

362

Corticosteroids: Potential  2Agonist and Anticholinergic Interactions in Chronic Obstructive Pulmonary Disease  

Microsoft Academic Search

Corticosteroids are often used in combination with 2-agonist and anticholinergicbronchodilatorsinthetreatmentofchronicobstruc- tive pulmonary disease (COPD). Corticosteroids activate the 2- receptor gene, increasing receptornumber and decreasing desensi- tization. Long-acting 2-agonists prime the glucocorticoid receptor and enhance nuclear translocation via activation of CCAAT en- hancerbindingprotein-.Corticosteroidscanalsoincreaseprejunc- tional auto-inhibitory M2-receptor gene expression in airway smooth muscle. There is evidence of a synergistic inhibition of cytokine

Malcolm Johnson

2005-01-01

363

Agonist and blocking actions of choline and tetramethylammonium on human muscle acetylcholine receptors  

Microsoft Academic Search

Choline has been used widely as an agonist for the investigation of gain-of-function mutants of the nicotinic acetylcholine receptor. It is useful because it behaves like a partial agonist. The efficacy of choline is difficult to measure because choline blocks the channel at concentrations about four times lower than those that activate it. We have fitted activation mechanisms to single-channel

Remigijus Lape; Paraskevi Krashia; David Colquhoun; Lucia G. Sivilotti

2009-01-01

364

Atomistic Detailed Mechanism and Weak Cation-Conducting Activity of HIV-1 Vpu Revealed by Free Energy Calculations  

PubMed Central

The viral protein U (Vpu) encoded by HIV-1 has been shown to assist in the detachment of virion particles from infected cells. Vpu forms cation-specific ion channels in host cells, and has been proposed as a potential drug target. An understanding of the mechanism of ion transport through Vpu is desirable, but remains limited because of the unavailability of an experimental structure of the channel. Using a structure of the pentameric form of Vpu – modeled and validated based on available experimental data – umbrella sampling molecular dynamics simulations (cumulative simulation time of more than 0.4 µs) were employed to elucidate the energetics and the molecular mechanism of ion transport in Vpu. Free energy profiles corresponding to the permeation of Na+ and K+ were found to be similar to each other indicating lack of ion selection, consistent with previous experimental studies. The Ser23 residue is shown to enhance ion transport via two mechanisms: creating a weak binding site, and increasing the effective hydrophilic length of the channel, both of which have previously been hypothesized in experiments. A two-dimensional free energy landscape has been computed to model multiple ion permeation, based on which a mechanism for ion conduction is proposed. It is shown that only one ion can pass through the channel at a time. This, along with a stretch of hydrophobic residues in the transmembrane domain of Vpu, explains the slow kinetics of ion conduction. The results are consistent with previous conductance studies that showed Vpu to be a weakly conducting ion channel. PMID:25392993

Padhi, Siladitya; Burri, Raghunadha Reddy; Jameel, Shahid; Priyakumar, U. Deva

2014-01-01

365

Effect of weak acid preservatives on growth of bakery product spoilage fungi at different water activities and pH values  

Microsoft Academic Search

Inhibition of spoilage organisms from bakery products by weak acid preservatives in concentrations of 0%, 0.003%, 0.03% and 0.3% (w\\/v) was investigated experimentally on a substrate media with water activity (aw) and pH ranging from sourdough-fermented acidic rye bread to alkaline intermediate moisture sponge cake types (aw 0.80–0.95, pH 4.7–7.4). Initially, rye bread conditions (aw 0.94–0.97 and pH 4.4–4.8) in

K. I Suhr; P. V Nielsen

2004-01-01

366

Dopamine agonists and risk: impulse control disorders in Parkinson's disease.  

PubMed

Impulse control disorders are common in Parkinson's disease, occurring in 13.6% of patients. Using a pharmacological manipulation and a novel risk taking task while performing functional magnetic resonance imaging, we investigated the relationship between dopamine agonists and risk taking in patients with Parkinson's disease with and without impulse control disorders. During functional magnetic resonance imaging, subjects chose between two choices of equal expected value: a 'Sure' choice and a 'Gamble' choice of moderate risk. To commence each trial, in the 'Gain' condition, individuals started at $0 and in the 'Loss' condition individuals started at -$50 below the 'Sure' amount. The difference between the maximum and minimum outcomes from each gamble (i.e. range) was used as an index of risk ('Gamble Risk'). Sixteen healthy volunteers were behaviourally tested. Fourteen impulse control disorder (problem gambling or compulsive shopping) and 14 matched Parkinson's disease controls were tested ON and OFF dopamine agonists. Patients with impulse control disorder made more risky choices in the 'Gain' relative to the 'Loss' condition along with decreased orbitofrontal cortex and anterior cingulate activity, with the opposite observed in Parkinson's disease co