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Sample records for rat pancreatic beta-cells

  1. Dopamine Modulates Insulin Release and Is Involved in the Survival of Rat Pancreatic Beta Cells

    PubMed Central

    Iglesias Osma, Maria Carmen; Blanco, Enrique J.; Carretero Hernández, Marta; Sánchez Robledo, Virginia; Catalano Iniesta, Leonardo; Carrero, Sixto

    2015-01-01

    The local synthesis of dopamine and its effects on insulin release have been described in isolated islets. Thus, it may be accepted that dopamine exerts an auto-paracrine regulation of insulin secretion from pancreatic beta cells. The aim of the present study is to analyze whether dopamine is a regulator of the proliferation and apoptosis of rat pancreatic beta cells after glucose-stimulated insulin secretion. Glucose stimulated pancreatic islets obtained from male Wistar rats were cultured with 1 or 10 μM dopamine from 1 to 12 h. Insulin secretion was analyzed by RIA. The cellular proliferation rate of pancreatic islets and beta cells was studied with immunocytochemical double labelling for both insulin and PCNA (proliferating cell nuclear antigen), and active caspase-3 was detected to evaluate apoptosis. The secretion of insulin from isolated islets was significantly inhibited (p<0.01), by treatment with 1 and 10 μM dopamine, with no differences between either dose as early as 1 h after treatment. The percentage of insulin-positive cells in the islets decreased significantly (p<0.01) after 1 h of treatment up to 12 h. The proliferation rate of insulin-positive cells in the islets decreased significantly (p<0.01) following treatment with dopamine. Apoptosis in pancreatic islets and beta cells was increased by treatment with 1 and 10 μM dopamine along 12 h. In conclusion, these results suggest that dopamine could modulate the proliferation and apoptosis of pancreatic beta cells and that dopamine may be involved in the maintenance of pancreatic islets. PMID:25886074

  2. Species-Related Differences in the Proteome of Rat and Human Pancreatic Beta Cells

    PubMed Central

    Martens, G. A.

    2015-01-01

    The core proteomes of human and rat pancreatic beta cells were compared by label-free LC-MS/MS: this resulted in quantification of relative molar abundances of 707 proteins belonging to functional pathways of intermediary metabolism, protein synthesis, and cytoskeleton. Relative molar abundances were conserved both within and between pathways enabling the selection of a housekeeping network for geometric normalization and the analysis of potentially relevant differential expressions. Human beta cells differed from rat beta cells in their lower level of enzymes involved in glucose sensing (MDH1, PC, and ACLY) and upregulation of lysosomal enzymes. Human cells also expressed more heat shock proteins and radical scavenging systems: apart from SOD2, they expressed high levels of H2O2-scavenger peroxiredoxin 3 (PRDX3), confirmed by microarray, Western blotting, and microscopy. Besides conferring lower susceptibility to oxidative stress to human cells PRDX3 might also play a role in physiological redox regulation as, in rat, its expression was restricted to a beta cell subset with higher metabolic glucose responsiveness. In conclusion, although their core proteomic architecture is conserved, human and rat beta cells differ in their molar expression of key enzymes involved in glucose sensing and redox control. PMID:26064985

  3. Increased androgen levels in rats impair glucose-stimulated insulin secretion through disruption of pancreatic beta cell mitochondrial function.

    PubMed

    Wang, Hongdong; Wang, Xiaping; Zhu, Yunxia; Chen, Fang; Sun, Yujie; Han, Xiao

    2015-11-01

    Although insulin resistance is recognized to contribute to the reproductive and metabolic phenotypes of polycystic ovary syndrome (PCOS), pancreatic beta cell dysfunction plays an essential role in the progression from PCOS to the development of type 2 diabetes. However, the role of insulin secretory abnormalities in PCOS has received little attention. In addition, the precise changes in beta cells and the underlying mechanisms remain unclear. In this study, we therefore attempted to elucidate potential mechanisms involved in beta cell alterations in a rat model of PCOS. Glucose-induced insulin secretion was measured in islets isolated from DHT-treated and control rats. Oxygen consumption rate (OCR), ATP production, and mitochondrial copy number were assayed to evaluate mitochondrial function. Glucose-stimulated insulin secretion is significantly decreased in islets from DHT-treated rats. On the other hand, significant reductions are observed in the expression levels of several key genes involved in mitochondrial biogenesis and in mitochondrial OCR and ATP production in DHT-treated rat islets. Meanwhile, we found that androgens can directly impair beta cell function by inducing mitochondrial dysfunction in vitro in an androgen receptor dependent manner. For the first time, our study demonstrates that increased androgens in female rats can impair glucose-stimulated insulin secretion partly through disruption of pancreatic beta cell mitochondrial function. This work has significance for hyperandrogenic women with PCOS: excess activation of the androgen receptor by androgens may provoke beta cell dysfunction via mitochondrial dysfunction. PMID:26348137

  4. Reduced Expression of the Liver/Beta-Cell Glucose Transporter Isoform in Glucose-Insensitive Pancreatic Beta Cells of Diabetic Rats

    NASA Astrophysics Data System (ADS)

    Thorens, Bernard; Weir, Gordon C.; Leahy, John L.; Lodish, Harvey F.; Bonner-Weir, Susan

    1990-09-01

    Rats injected with a single dose of streptozocin at 2 days of age develop non-insulin-dependent diabetes 6 weeks later. The pancreatic beta islet cells of these diabetic rats display a loss of glucose-induced insulin secretion while maintaining sensitivity to other secretagogues such as arginine. We analyzed the level of expression of the liver/beta-cell glucose transporter isoform in diabetic islets by immunofluorescence staining of pancreas sections and by Western blotting of islet lysates. Islets from diabetic animals have a reduced expression of this beta-cell-specific glucose transporter isoform and the extent of reduction is correlated with the severity of hyperglycemia. In contrast, expression of this transporter isoform in liver is minimally modified by the diabetes. Thus a decreased expression of the liver/beta-cell glucose transporter isoform in beta cells is associated with the impaired glucose sensing characteristic of diabetic islets; our data suggest that this glucose transporter may be part of the beta-cell glucose sensor.

  5. A quantitative study of sodium tungstate protective effect on pancreatic beta cells in streptozotocin-induced diabetic rats.

    PubMed

    Heidari, Zahra; Mahmoudzadeh-Sagheb, Hamidreza; Moudi, Bita

    2008-12-01

    Diabetes is a major public health problem. Development of new therapies that are able to improve glycemia management, cure diabetes, and can even protect from it, are of great interest. This study investigated the protective effect of sodium tungstate against STZ-induced beta-cell damages by means of stereological methods. Sixty rats were divided into six groups: control (C), tungstate-treated control (TC), STZ-induced diabetic (D), STZ-induced diabetic rats were treated by sodium tungstate from 1 week before STZ injection (TDB), food-restricted diabetic (FRD), and diabetic rats treated with sodium tungstate 1 week after STZ administration (TDA). Stereological estimation of pancreas volume, islets volume density, volume-weighted mean islets volume and mass of beta cells, islets, and pancreas and total number of islets were done. Islets volume density, volume-weighted mean islets volume, and mass of beta cells, islets, and pancreas of TDB group was significantly higher than D, FRD and TDA groups (P<0.001) and was comparable to controls (C and TC groups). Total number of islets, pancreas wet weight and volume did not show any significant changes between these groups (P>0.05). Results suggested that sodium tungstate preserves pancreatic beta cells from STZ-induced damages and diabetes induction in rats. PMID:18400503

  6. Properties of single potassium channels modulated by glucose in rat pancreatic beta-cells.

    PubMed Central

    Ashcroft, F M; Ashcroft, S J; Harrison, D E

    1988-01-01

    1. The patch clamp method has been used to examine the effect of glucose on single K+ channel currents recorded from cell-attached patches on dissociated rat pancreatic beta-cells. Patch pipettes contained a 140 mM-K+ solution. 2. In glucose-free solution three types of K+ channels were observed. Two of these, having conductances of around 50 pS (G-channel) and 20 pS when the external K+ concentration, [K+]0, was 140 mM, were active at the resting potential of the cell. The G-channel was observed in more patches and showed higher activity; it therefore appears to contribute the major fraction of the resting K+ permeability of the beta-cell. At membrane potentials positive to about +20 mV a third type of K+ channel, having a mean conductance of 120 pS, was activated. The open probability of this channel was strongly voltage dependent and increased with depolarization. 3. The reversal potential of the G-channel current was shifted 59 mV by a 10-fold change in external K+ (Na+ substitution) indicating the channel is highly K+ selective. The single-channel conductance varied with [K+]o as predicted from the Goldman-Hodgkin-Katz equation; at physiological [K+]o (5 mM-K+) an inward conductance of around 10 pS is predicted. The amplitude of the single-channel current showed a tendency to saturate with increasing [K+]o. 4. Single G-channel currents show burst kinetics indicating at least two closed states. The open and closed (gap) times within the bursts were distributed exponentially with time constants of 2.5 ms (tau o) and 0.5 ms (tau c1) respectively at the resting potential of the cell. There was little change in tau c1 over the voltage range -40 to 60 mV (pipette potential) but tau o increased slightly with membrane depolarization. 5. The addition of glucose to the bath solution produced a reversible, dose-dependent decrease in G-channel activity. This decrease results principally from a reduction in the frequency and duration of the bursts of openings with

  7. BACE2 is stored in secretory granules of mouse and rat pancreatic beta cells.

    PubMed

    Finzi, Giovanna; Franzi, Francesca; Placidi, Claudia; Acquati, Francesco; Palumbo, Elisa; Russo, Antonella; Taramelli, Roberto; Sessa, Fausto; La Rosa, Stefano

    2008-01-01

    BACE2 is a protease homologous to BACE1 protein, an enzyme involved in the amyloid formation of Alzheimer disease (AD). However, despite the high homology between these two proteins, the biological role of BACE2 is still controversial, even though a few studies have suggested a pathogenetic role in sporadic inclusion-body myositis and hereditary inclusion-body myopathy, which are characterized by vacuolization of muscular fibers with intracellular deposits of proteins similar to those found in the brain of AD patients. Although BACE2 has also been identified in the pancreas, its function remains unknown and its specific localization in different pancreatic cell types has not been definitively ascertained. For these reasons, the authors have investigated the cellular and subcellular localization of BACE2 in normal rodent pancreases. BACE2 immunoreactivity was found in secretory granules of beta cells, co-stored with insulin and IAPP, while it was lacking in the other endocrine and exocrine cell types. The presence of BACE2 in secretory granules of beta cells suggests that it may play a role in diabetes-associated amyloidogenesis. PMID:19117266

  8. Protective effect of Withania somnifera against oxidative stress and pancreatic beta-cell damage in type 2 diabetic rats.

    PubMed

    Anwer, Tarique; Sharma, Manju; Pillai, Krishna Kolappa; Khan, Gyas

    2012-01-01

    The aim of the present study was to investigate the effects of Withania somnifera (WS) on lipid peroxidation (LPO), activities of both non-enzymatic and enzymatic antioxidants and histopathological examination of pancreas in type 2 diabetic rats. Type 2 diabetes was induced by single intraperitoneal injection of STZ (100 mg/kg) to 2 days old rat pups. Oxidative stress was measured by tissue LPO levels, reduced glutathione (GSH) contents and by enzymatic activities of glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT). Administration of WS to type 2 diabetic rats caused a significant decrease in blood glucose and tissue LPO levels with significant increase in GSH contents when compared with the type 2 diabetic control rats. In addition, WS treated rats also showed a significant increase in the activities of antioxidant enzymes namely GPx, GR, GST, SOD and CAT when compared with type 2 diabetic control rats. Significant reduction in the number and size of pancreatic beta-cells were preserved to near normal morphology by the administration of WS in type 2 diabetic rats as evident from histopathological examination. The results obtained clearly indicate that WS has shown strong free radical scavenging activity and helped in improving the non-enzymatic and enzymatic antioxidants in type 2 diabetic rats. PMID:23285670

  9. Glucolipotoxicity of the Pancreatic Beta Cell

    PubMed Central

    Poitout, Vincent; Amyot, Julie; Semache, Meriem; Zarrouki, Bader; Hagman, Derek; Fontés, Ghislaine

    2009-01-01

    Summary The concept of glucolipotoxicity refers to the combined, deleterious effects of elevated glucose and fatty acid levels on pancreatic beta-cell function and survival. Significant progress has been made in recent years towards a better understanding of the cellular and molecular basis of glucolipotoxicity in the beta cell. The permissive effect of elevated glucose on the detrimental actions of fatty acids stems from the influence of glucose on intracellular fatty-acid metabolism, promoting the synthesis of cellular lipids. The combination of excessive levels of fatty acids and glucose therefore leads to decreased insulin secretion, impaired insulin gene expression, and beta-cell death by apoptosis, all of which probably have distinct underlying mechanisms. Recent studies from our laboratory have identified several pathways implicated in fatty-acid inhibition of insulin gene expression, including the extracellular-regulated kinase (ERK1/2) pathway; the metabolic sensor Per-Arnt-Sim kinase (PASK); and the ATF6 branch of the unfolded protein response. We have also confirmed in vivo in rats that the decrease in insulin gene expression is an early defect which precedes any detectable abnormality in insulin secretion. While the role of glucolipotoxicity in humans is still debated, the inhibitory effects of chronically elevated fatty acid levels has been clearly demonstrated in several studies, at least in individuals genetically predisposed to developing type 2 diabetes. It is therefore likely that glucolipotoxicity contributes to beta-cell failure in type 2 diabetes as well as to the decline in beta-cell function observed after the onset of the disease. PMID:19715772

  10. Regulation of pancreatic beta-cell mass.

    PubMed

    Bouwens, Luc; Rooman, Ilse

    2005-10-01

    Beta-cell mass regulation represents a critical issue for understanding diabetes, a disease characterized by a near-absolute (type 1) or relative (type 2) deficiency in the number of pancreatic beta cells. The number of islet beta cells present at birth is mainly generated by the proliferation and differentiation of pancreatic progenitor cells, a process called neogenesis. Shortly after birth, beta-cell neogenesis stops and a small proportion of cycling beta cells can still expand the cell number to compensate for increased insulin demands, albeit at a slow rate. The low capacity for self-replication in the adult is too limited to result in a significant regeneration following extensive tissue injury. Likewise, chronically increased metabolic demands can lead to beta-cell failure to compensate. Neogenesis from progenitor cells inside or outside islets represents a more potent mechanism leading to robust expansion of the beta-cell mass, but it may require external stimuli. For therapeutic purposes, advantage could be taken from the surprising differentiation plasticity of adult pancreatic cells and possibly also from stem cells. Recent studies have demonstrated that it is feasible to regenerate and expand the beta-cell mass by the application of hormones and growth factors like glucagon-like peptide-1, gastrin, epidermal growth factor, and others. Treatment with these external stimuli can restore a functional beta-cell mass in diabetic animals, but further studies are required before it can be applied to humans. PMID:16183912

  11. Beneficial effects of Murraya koenigii leaves on antioxidant defense system and ultra structural changes of pancreatic beta-cells in experimental diabetes in rats.

    PubMed

    Arulselvan, Palanisamy; Subramanian, Sorimuthu Pillai

    2007-01-30

    Oxidative stress and oxidative damage to tissues are common end points of chronic diseases such as atherosclerosis, diabetes, and rheumatoid arthritis. Oxidative stress in diabetes coexists with a reduction in the antioxidant status, which can further increase the deleterious effects of free radicals. The aim of the present study was to evaluate the possible protective effects of Murraya koenigii leaves extract against beta-cell damage and antioxidant defense systems of plasma and pancreas in streptozotocin induced diabetes in rats. The levels of glucose and glycosylated hemoglobin in blood and insulin, Vitamin C, Vitamin E, ceruloplasmin, reduced glutathione and TBARS were estimated in plasma of control and experimental groups of rats. To assess the changes in the cellular antioxidant defense system such as the level of reduced glutathione and activities of superoxide dismutase, catalase and glutathione peroxidase were assayed in pancreatic tissue homogenate. The levels of glucose, glycosylated hemoglobin, insulin, TBARS, enzymatic and non-enzymatic antioxidants were altered in diabetic rats. These alterations were reverted back to near control levels after the treatment of M. koenigii leaves extract. Transmission electron microscopic studies also revealed the protective nature of M. koenigii leaves on pancreatic beta-cells. These findings suggest that M. koenigii treatment exerts a therapeutic protective nature in diabetes by decreasing oxidative stress and pancreatic beta-cell damage. The antioxidant effect of the M. koenigii extract was compared with glibenclamide, a well-known hypoglycemic drug. PMID:17188670

  12. Extracellular ATP stimulates exocytosis via localized Ca(2+) release from acidic stores in rat pancreatic beta cells.

    PubMed

    Xie, Li; Zhang, Ming; Zhou, Wei; Wu, Zhengxing; Ding, Jiuping; Chen, Liangyi; Xu, Tao

    2006-04-01

    Three different methods, membrane capacitance (C(m)) measurement, amperometry and FM dye labeling were used to investigate the role of extracellular ATP in insulin secretion from rat pancreatic beta cells. We found that extracellular application of ATP mobilized intracellular Ca(2+) stores and synchronously triggered vigorous exocytosis. No influence of ATP on the readily releasable pool of vesicles was observed, which argues against a direct modulation of the secretory machinery at a level downstream of Ca(2+) elevation. The stimulatory effects of ATP were greatly reduced by intracellular perfusion of BAPTA but not EGTA, suggesting a close spatial association of fusion sites with intracellular Ca(2+) releasing sites. ATP-induced Ca(2+) transients and exocytosis were not blocked by thapsigargin (TG), by a ryanodine receptor antagonist or by dissipation of pH in acidic stores by monensin alone, but they were greatly attenuated by IP(3) receptor inhibition as well as ionomycin plus monensin, suggesting involvement of IP(3)-sensitive acidic Ca(2+) stores. Taken together, our data suggest that extracellular ATP triggers exocytosis by mobilizing spatially limited acidic Ca(2+) stores through IP(3) receptors. This mechanism may explain how insulin secretion from the pancreas is coordinated through diffusible ATP that is co-released with insulin. PMID:16536741

  13. Detailed transcriptome atlas of the pancreatic beta cell

    PubMed Central

    Kutlu, Burak; Burdick, David; Baxter, David; Rasschaert, Joanne; Flamez, Daisy; Eizirik, Decio L; Welsh, Nils; Goodman, Nathan; Hood, Leroy

    2009-01-01

    Background Gene expression patterns provide a detailed view of cellular functions. Comparison of profiles in disease vs normal conditions provides insights into the processes underlying disease progression. However, availability and integration of public gene expression datasets remains a major challenge. The aim of the present study was to explore the transcriptome of pancreatic islets and, based on this information, to prepare a comprehensive and open access inventory of insulin-producing beta cell gene expression, the Beta Cell Gene Atlas (BCGA). Methods We performed Massively Parallel Signature Sequencing (MPSS) analysis of human pancreatic islet samples and microarray analyses of purified rat beta cells, alpha cells and INS-1 cells, and compared the information with available array data in the literature. Results MPSS analysis detected around 7600 mRNA transcripts, of which around a third were of low abundance. We identified 2000 and 1400 transcripts that are enriched/depleted in beta cells compared to alpha cells and INS-1 cells, respectively. Microarray analysis identified around 200 transcription factors that are differentially expressed in either beta or alpha cells. We reanalyzed publicly available gene expression data and integrated these results with the new data from this study to build the BCGA. The BCGA contains basal (untreated conditions) gene expression level estimates in beta cells as well as in different cell types in human, rat and mouse pancreas. Hierarchical clustering of expression profile estimates classify cell types based on species while beta cells were clustered together. Conclusion Our gene atlas is a valuable source for detailed information on the gene expression distribution in beta cells and pancreatic islets along with insulin producing cell lines. The BCGA tool, as well as the data and code used to generate the Atlas are available at the T1Dbase website (T1DBase.org). PMID:19146692

  14. Rat neonatal beta cells lack the specialised metabolic phenotype of mature beta cells

    PubMed Central

    Jermendy, A.; Toschi, E.; Aye, T.; Koh, A.; Aguayo-Mazzucato, C.; Sharma, A.; Weir, G. C.; Sgroi, D.

    2011-01-01

    Aims/hypothesis Fetal and neonatal beta cells have poor glucose-induced insulin secretion and only gain robust glucose responsiveness several weeks after birth. We hypothesise that this unresponsiveness is due to a generalised immaturity of the metabolic pathways normally found in beta cells rather than to a specific defect. Methods Using laser-capture microdissection we excised beta cell-enriched cores of pancreatic islets from day 1 (P1) neonatal and young adult Sprague–Dawley rats in order to compare their gene-expression profiles using Affymetrix U34A microarrays (neonatal, n=4; adult, n=3). Results Using dChip software for analysis, 217 probe sets for genes/38 expressed sequence tags (ESTs) were significantly higher and 345 probe sets for genes/33 ESTs significantly lower in beta cell-enriched cores of neonatal islets compared with those of adult islets. Among the genes lower in the neonatal beta cells were key metabolic genes including mitochondrial shuttles (malate dehydrogenase, glycerol-3-phosphate dehydrogenase and glutamate oxalacetate transaminase), pyruvate carboxylase and carnitine palmitoyl transferase 2. Differential expression of these enzyme genes was confirmed by quantitative PCR on RNA from isolated neonatal (P2 until P28) and adult islets and with immunostaining of pancreas. Even by 28 days of age some of these genes were still expressed at lower levels than in adults. Conclusions/interpretation The lack of glucose responsiveness in neonatal islets is likely to be due to a generalised immaturity of the metabolic specialisation of pancreatic beta cells. PMID:21240476

  15. Positron emission tomography study on pancreatic somatostatin receptors in normal and diabetic rats with {sup 68}Ga-DOTA-octreotide: A potential PET tracer for beta cell mass measurement

    SciTech Connect

    Sako, Takeo; Hasegawa, Koki; Nishimura, Mie; Kanayama, Yousuke; Wada, Yasuhiro; Hayashinaka, Emi; Cui, Yilong; Kataoka, Yosky; Senda, Michio; Watanabe, Yasuyoshi

    2013-12-06

    Highlights: •PET images showed high uptake of {sup 68}Ga-DOTA-octreotide in the normal pancreas. •{sup 68}Ga-DOTA-octreotide specifically binds to somatostatin receptors in the pancreas. •The pancreatic uptake of {sup 68}Ga-DOTA-octreotide was decreased in the diabetic rats. •{sup 68}Ga-DOTA-octreotide could be a candidate PET probe to measure the beta cell mass. -- Abstract: Diabetes mellitus (DM) is a metabolic disorder characterized by hyperglycemia, and the loss or dysfunction of pancreatic beta cells has been reported before the appearance of clinical symptoms and hyperglycemia. To evaluate beta cell mass (BCM) for improving the detection and treatment of DM at earlier stages, we focused on somatostatin receptors that are highly expressed in the pancreatic beta cells, and developed a positron emission tomography (PET) probe derived from octreotide, a metabolically stable somatostatin analog. Octreotide was conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), a chelating agent, and labeled with {sup 68}Gallium ({sup 68}Ga). After intravenous injection of {sup 68}Ga-DOTA-octreotide, a 90-min emission scan of the abdomen was performed in normal and DM model rats. The PET studies showed that {sup 68}Ga-DOTA-octreotide radioactivity was highly accumulated in the pancreas of normal rats and that the pancreatic accumulation was significantly reduced in the rats administered with an excess amount of unlabeled octreotide or after treatment with streptozotocin, which was used for the chemical induction of DM in rats. These results were in good agreement with the ex vivo biodistribution data. These results indicated that the pancreatic accumulation of {sup 68}Ga-DOTA-octreotide represented specific binding to the somatostatin receptors and reflected BCM. Therefore, PET imaging with {sup 68}Ga-DOTA-octreotide could be a potential tool for evaluating BCM.

  16. ADVANCES IN MOLECULAR IMAGING OF PANCREATIC BETA CELLS

    PubMed Central

    Lin, Mai; Lubag, Angelo; McGuire, Michael J.; Seliounine, Serguei Y.; Tsyganov, Edward N.; Antich, Peter P.; Sherry, A. Dean; Brown, Kathlynn C.; Sun, Xiankai

    2009-01-01

    The development of non-invasive imaging methods for early diagnosis of the beta cell associated metabolic diseases, including type 1 and type 2 diabetes (T1D and T2D), has recently drawn considerable interest from the molecular imaging community as well as clinical investigators. Due to the challenges imposed by the location of the pancreas, the sparsely dispersed beta cell population within the pancreas, and the poor understanding of the pathogenesis of the diseases, clinical diagnosis of beta cell abnormalities is still limited. Current diagnostic methods are invasive, often inaccurate, and usually performed post-onset of the disease. Advances in imaging techniques for probing beta cell mass and function are needed to address this critical health care problem. A variety of currently available imaging techniques have been tested for the assessment of the pancreatic beta cell islets. Here we discuss the current advances in magnetic resonance imaging (MRI), bioluminescence imaging (BLI), and nuclear imaging for the study of beta cell diseases. Spurred by early successes in nuclear imaging techniques for beta cells, especially positron emission tomography (PET), the need for beta cell specific ligands has expanded. Progress in the field for obtaining such ligands is presented. Additionally, we report our preliminary efforts of developing such a peptidic ligand for PET imaging of the pancreatic beta cells. PMID:18508529

  17. Pancreatic beta-cell hyperactivity in morbidly obese adolescents.

    PubMed

    Mercado, Arlene B; Castells, Salvador

    2006-12-01

    beta-cell hyperactivity, with increased beta-cell mass in the pancreas, contributes to insulin oversecretion in response to insulin resistance. beta-cell mass expansion, also known as "endocrine pancreas plasticity", is an adaptation to variations in insulin demand, is generally observed in obese persons and in women during late pregnancy. In obese persons, increased free fatty acids contribute to beta-cell growth. It is believed that type 2 diabetes develops in those persons unable to respond to an increased insulin demand with a high rate of beta-cell proliferation. Impairment of insulin secretion may originate from a genetic predisposition as well as aggravated by high lipid and glucose levels. Better understanding of endocrine pancreas plasticity and its regeneration mechanisms could lead to new treatment modalities for type 2 diabetes. Review of literature of pancreatic beta-cell hyperactivity in obesity and its existence in morbidly obese adolescents is hereby presented. PMID:17237743

  18. Arsenite reduces insulin secretion in rat pancreatic {beta}-cells by decreasing the calcium-dependent calpain-10 proteolysis of SNAP-25

    SciTech Connect

    Diaz-Villasenor, Andrea; Burns, Anna L.; Salazar, Ana Maria; Sordo, Monserrat; Hiriart, Marcia; Cebrian, Mariano E.; Ostrosky-Wegman, Patricia

    2008-09-15

    An increase in the prevalence of type 2 diabetes has been consistently observed among residents of high arsenic exposure areas. We have previously shown that in rat pancreatic {beta}-cells, low arsenite doses impair the secretion of insulin without altering its synthesis. To further study the mechanism by which arsenite reduces insulin secretion, we evaluated the effects of arsenite on the calcium-calpain pathway that triggers insulin exocytosis in RINm5F cells. Cell cycle and proliferation analysis were also performed to complement the characterization. Free [Ca{sup 2+}]i oscillations needed for glucose-stimulated insulin secretion were abated in the presence of subchronic low arsenite doses (0.5-2 {mu}M). The global activity of calpains increased with 2 {mu}M arsenite. However, during the secretion of insulin stimulated with glucose (15.6 mM), 1 {mu}M arsenite decreased the activity of calpain-10, measured as SNAP-25 proteolysis. Both proteins are needed to fuse insulin granules with the membrane to produce insulin exocytosis. Arsenite also induced a slowdown in the {beta} cell line proliferation in a dose-dependent manner, reflected by a reduction of dividing cells and in their arrest in G2/M. Data obtained showed that one of the mechanisms by which arsenite impairs insulin secretion is by decreasing the oscillations of free [Ca{sup 2+}]i, thus reducing calcium-dependent calpain-10 partial proteolysis of SNAP-25. The effects in cell division and proliferation observed with arsenite exposure can be an indirect consequence of the decrease in insulin secretion.

  19. Human Fucci Pancreatic Beta Cell Lines: New Tools to Study Beta Cell Cycle and Terminal Differentiation

    PubMed Central

    Carlier, Géraldine; Maugein, Alicia; Cordier, Corinne; Pechberty, Séverine; Garfa-Traoré, Meriem; Martin, Patrick; Scharfmann, Raphaël; Albagli, Olivier

    2014-01-01

    Regulation of cell cycle in beta cells is poorly understood, especially in humans. We exploited here the recently described human pancreatic beta cell line EndoC-βH2 to set up experimental systems for cell cycle studies. We derived 2 populations from EndoC-βH2 cells that stably harbor the 2 genes encoding the Fucci fluorescent indicators of cell cycle, either from two vectors, or from a unique bicistronic vector. In proliferating non-synchronized cells, the 2 Fucci indicators revealed cells in the expected phases of cell cycle, with orange and green cells being in G1 and S/G2/M cells, respectively, and allowed the sorting of cells in different substeps of G1. The Fucci indicators also faithfully red out alterations in human beta cell proliferative activity since a mitogen-rich medium decreased the proportion of orange cells and inflated the green population, while reciprocal changes were observed when cells were induced to cease proliferation and increased expression of some beta cell genes. In the last situation, acquisition of a more differentiated beta cell phenotype correlates with an increased intensity in orange fluorescence. Hence Fucci beta cell lines provide new tools to address important questions regarding human beta cell cycle and differentiation. PMID:25259951

  20. Proliferating pancreatic beta-cells upregulate ALDH.

    PubMed

    Liu, Yinglan; Jiang, Xiaoxin; Zeng, Yong; Zhou, Hui; Yang, Jing; Cao, Renxian

    2014-12-01

    High levels of aldehyde dehydrogenase (ALDH) activity have been regarded as a specific feature of progenitor cells and stem cells. Hence, as an indicator of ALDH activity, aldefluor fluorescence has been widely used for the identification and isolation of stem and progenitor cells. ALDH activity was recently detected in embryonic mouse pancreas, and specifically and exclusively in adult centroacinar and terminal duct cells, suggesting that these duct cells may harbor cells of endocrine and exocrine differentiation potential in the adult pancreas. Here, we report the presence of aldefluor+ beta-cells in a beta-cell proliferation model, partial pancreatectomy. The aldefluor+ beta-cells are essentially all positive for Ki-67 and expressed high levels of cell-cycle activators such as CyclinD1, CyclinD2, and CDK4, suggesting that they are mitotic cells. Our data thus reveal a potential change in ALDH activity of proliferating beta-cells, which provides a novel method for the isolation and analysis of proliferating beta-cells. Moreover, our data also suggest that aldefluor lineage-tracing is not a proper method for analyzing progenitor or stem activity in the adult pancreas. PMID:25028343

  1. Uncovering Factors Related to Pancreatic Beta-Cell Function

    PubMed Central

    Curran, Aoife M.; Ryan, Miriam F.; Drummond, Elaine; Gibney, Eileen R.; Gibney, Michael J.; Roche, Helen M.; Brennan, Lorraine

    2016-01-01

    Aim The incidence of type 2 diabetes has increased rapidly on a global scale. Beta-cell dysfunction contributes to the overall pathogenesis of type 2 diabetes. However, factors contributing to beta-cell function are not clear. The aims of this study were (i) to identify factors related to pancreatic beta-cell function and (ii) to perform mechanistic studies in vitro. Methods Three specific measures of beta-cell function were assessed for 110 participants who completed an oral glucose tolerance test as part of the Metabolic Challenge Study. Anthropometric and biochemical parameters were assessed as potential modulators of beta-cell function. Subsequent in vitro experiments were performed using the BRIN-BD11 pancreatic beta-cell line. Validation of findings were performed in a second human cohort. Results Waist-to-hip ratio was the strongest anthropometric modulator of beta-cell function, with beta-coefficients of -0.33 (p = 0.001) and -0.30 (p = 0.002) for beta-cell function/homeostatic model assessment of insulin resistance (HOMA-IR), and disposition index respectively. Additionally, the resistin-to-adiponectin ratio (RA index) emerged as being strongly associated with beta-cell function, with beta-coefficients of -0.24 (p = 0.038) and -0.25 (p = 0.028) for beta-cell function/HOMA-IR, and disposition index respectively. Similar results were obtained using a third measure for beta-cell function. In vitro experiments revealed that the RA index was a potent regulator of acute insulin secretion where a high RA index (20ng ml-1 resistin, 5nmol l-1 g-adiponectin) significantly decreased insulin secretion whereas a low RA index (10ng ml-1 resistin, 10nmol l-1 g-adiponectin) significantly increased insulin secretion. The RA index was successfully validated in a second human cohort with beta-coefficients of -0.40 (p = 0.006) and -0.38 (p = 0.008) for beta-cell function/ HOMA-IR, and disposition index respectively. Conclusions Waist-to-hip ratio and RA index were identified

  2. Conversion of adult pancreatic alpha-cells to beta-cells after extreme beta-cell loss.

    PubMed

    Thorel, Fabrizio; Népote, Virginie; Avril, Isabelle; Kohno, Kenji; Desgraz, Renaud; Chera, Simona; Herrera, Pedro L

    2010-04-22

    Pancreatic insulin-producing beta-cells have a long lifespan, such that in healthy conditions they replicate little during a lifetime. Nevertheless, they show increased self-duplication after increased metabolic demand or after injury (that is, beta-cell loss). It is not known whether adult mammals can differentiate (regenerate) new beta-cells after extreme, total beta-cell loss, as in diabetes. This would indicate differentiation from precursors or another heterologous (non-beta-cell) source. Here we show beta-cell regeneration in a transgenic model of diphtheria-toxin-induced acute selective near-total beta-cell ablation. If given insulin, the mice survived and showed beta-cell mass augmentation with time. Lineage-tracing to label the glucagon-producing alpha-cells before beta-cell ablation tracked large fractions of regenerated beta-cells as deriving from alpha-cells, revealing a previously disregarded degree of pancreatic cell plasticity. Such inter-endocrine spontaneous adult cell conversion could be harnessed towards methods of producing beta-cells for diabetes therapies, either in differentiation settings in vitro or in induced regeneration. PMID:20364121

  3. Adhesion of pancreatic beta cells to biopolymer films.

    PubMed

    Williams, S Janette; Wang, Qun; Macgregor, Ronal R; Siahaan, Teruna J; Stehno-Bittel, Lisa; Berkland, Cory

    2009-08-01

    Dramatic reversal of Type 1 diabetes in patients receiving pancreatic islet transplants continues to prompt vigorous research concerning the basic mechanisms underlying patient turnaround. At the most fundamental level, transplanted islets must maintain viability and function in vitro and in vivo and should be protected from host immune rejection. Our previous reports showed enhancement of islet viability and insulin secretion per tissue mass for small islets (<125 mum) as compared with large islets (>125 mum), thus, demonstrating the effect of enhancing the mass transport of islets (i.e. increasing tissue surface area to volume ratio). Here, we report the facile dispersion of rat islets into individual cells that are layered onto the surface of a biopolymer film towards the ultimate goal of improving mass transport in islet tissue. The tightly packed structure of intact islets was disrupted by incubating in calcium-free media resulting in fragmented islets, which were further dispersed into individual or small groups of cells by using a low concentration of papain. The dispersed cells were screened for adhesion to a range of biopolymers and the nature of cell adhesion was characterized for selected groups by quantifying adherent cells, measuring the surface area coverage of the cells, and immunolabeling cells for adhesion proteins interacting with selected biopolymers. Finally, beta cells in suspension were centrifuged to form controlled numbers of cell layers on films for future work determining the mass transport limitations in the adhered tissue constructs. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 676-685, 2009.This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com. PMID:19353639

  4. The effect of smoking cessation pharmacotherapies on pancreatic beta cell function

    SciTech Connect

    Woynillowicz, Amanda K.; Raha, Sandeep; Nicholson, Catherine J.; Holloway, Alison C.

    2012-11-15

    The goal of our study was to evaluate whether drugs currently used for smoking cessation (i.e., nicotine replacement therapy, varenicline [a partial agonist at nicotinic acetylcholine receptors (nAChR)] and bupropion [which acts in part as a nAChR antagonist]) can affect beta cell function and determine the mechanism(s) of this effect. INS-1E cells, a rat beta cell line, were treated with nicotine, varenicline and bupropion to determine their effects on beta cell function, mitochondrial electron transport chain enzyme activity and cellular/oxidative stress. Treatment of INS-1E cells with equimolar concentrations (1 μM) of three test compounds resulted in an ablation of normal glucose-stimulated insulin secretion by the cells. This disruption of normal beta cell function was associated with mitochondrial dysfunction since all three compounds tested significantly decreased the activity of mitochondrial electron transport chain enzyme activity. These results raise the possibility that the currently available smoking cessation pharmacotherapies may also have adverse effects on beta cell function and thus glycemic control in vivo. Therefore whether or not the use of nicotine replacement therapy, varenicline and bupropion can cause endocrine changes which are consistent with impaired pancreatic function warrants further investigation. -- Highlights: ► Smoking cessation drugs have the potential to disrupt beta cell function in vitro. ► The effects of nicotine, varenicline and bupropion are similar. ► The impaired beta cell function is mediated by mitochondrial dysfunction. ► If similar effects are seen in vivo, these drugs may increase the risk of diabetes.

  5. D-saccharic acid-1,4-lactone ameliorates alloxan-induced diabetes mellitus and oxidative stress in rats through inhibiting pancreatic beta-cells from apoptosis via mitochondrial dependent pathway

    SciTech Connect

    Bhattacharya, Semantee; Manna, Prasenjit; Sil, Parames C.

    2011-12-15

    Oxidative stress plays a vital role in diabetic complications. To suppress the oxidative stress mediated damage in diabetic pathophysiology, a special focus has been given on naturally occurring antioxidants present in normal diet. D-saccharic acid 1,4-lactone (DSL), a derivative of D-glucaric acid, is present in many dietary plants and is known for its detoxifying and antioxidant properties. The aim of the present study was to evaluate the beneficial role of DSL against alloxan (ALX) induced diabetes in the pancreas tissue of Swiss albino rats. A dose-dependent study for DSL (20-120 mg/kg body weight) was carried out to find the effective dose of the compound in ALX-induced diabetic rats. ALX exposure elevated the blood glucose, glycosylated Hb, decreased the plasma insulin and disturbed the intra-cellular antioxidant machineries whereas oral administration of DSL at a dose of 80 mg/kg body weight restored these alterations close to normal. Investigating the mechanism of the protective activity of DSL we observed that it prevented the pancreatic {beta}-cell apoptosis via mitochondria-dependent pathway. Results showed decreased mitochondrial membrane potential, enhanced cytochrome c release in the cytosol and reciprocal regulation of Bcl-2 family proteins in the diabetic rats. These events were also found to be associated with increased level of Apaf-1, caspase 9, and caspase 3 that ultimately led to pancreatic {beta}-cell apoptosis. DSL treatment, however, counteracted these changes. In conclusion, DSL possesses the capability of ameliorating the oxidative stress in ALX-induced diabetes and thus could be a promising approach in lessening diabetic complications. Highlights: Black-Right-Pointing-Pointer Oxidative stress is suggested as a key event in the pathogenesis of diabetes. Black-Right-Pointing-Pointer D-saccharic acid 1,4-lactone (DSL) reduces the alloxan-induced diabetes mellitus. Black-Right-Pointing-Pointer DSL normalizes cellular antioxidant machineries

  6. Sodium arsenite impairs insulin secretion and transcription in pancreatic {beta}-cells

    SciTech Connect

    Diaz-Villasenor, Andrea; Sanchez-Soto, M. Carmen; Cebrian, Mariano E.; Ostrosky-Wegman, Patricia; Hiriart, Marcia . E-mail: mhiriart@ifc.unam.mx

    2006-07-01

    Human studies have shown that chronic inorganic arsenic (iAs) exposure is associated with a high prevalence and incidence of type 2 diabetes. However, the mechanism(s) underlying this effect are not well understood, and practically, there is no information available on the effects of arsenic on pancreatic {beta}-cells functions. Thus, since insulin secreted by the pancreas plays a crucial role in maintaining glucose homeostasis, our aim was to determine if sodium arsenite impairs insulin secretion and mRNA expression in single adult rat pancreatic {beta}-cells. Cells were treated with 0.5, 1, 2, 5 and 10 {mu}M sodium arsenite and incubated for 72 and 144 h. The highest dose tested (10 {mu}M) decreased {beta}-cell viability, by 33% and 83%, respectively. Insulin secretion and mRNA expression were evaluated in the presence of 1 and 5 {mu}M sodium arsenite. Basal insulin secretion, in 5.6 mM glucose, was not significantly affected by 1 or 5 {mu}M treatment for 72 h, but basal secretion was reduced when cells were exposed to 5 {mu}M sodium arsenite for 144 h. On the other hand, insulin secretion in response to 15.6 mM glucose decreased with sodium arsenite in a dose-dependent manner in such a way that cells were no longer able to distinguish between different glucose concentrations. We also showed a significant decrease in insulin mRNA expression of cells exposed to 5 {mu}M sodium arsenite during 72 h. Our data suggest that arsenic may contribute to the development of diabetes mellitus by impairing pancreatic {beta}-cell functions, particularly insulin synthesis and secretion.

  7. The role of autophagy in pancreatic beta-cell and diabetes.

    PubMed

    Fujitani, Yoshio; Kawamori, Ryuzo; Watada, Hirotaka

    2009-02-01

    Pancreatic beta-cells play a key role in glucose homeostasis in mammals. Although large-scale protein synthesis and degradation occur in pancreatic beta-cells, the mechanism underlying dynamic protein turnover in beta-cells remains largely unknown. We found low-level constitutive autophagy in beta-cells of C57BL/6 mice fed a standard diet; however, autophagy was markedly upregulated in mice fed a high-fat diet. beta-cells of diabetic db/db mice contained large numbers of autophagosomes, compared with nondiabetic db/misty controls. The functional importance of autophagy was analyzed using beta-cell-specific Atg7 knockout mice. Autophagy-deficient mice showed degeneration of beta-cells and impaired glucose tolerance with reduced insulin secretion. While a high-fat diet stimulated beta-cell autophagy in control mice, it induced a profound deterioration of glucose intolerance in beta-cell autophagy-deficient mutants, partly because of the lack of a compensatory increase in beta-cell mass. These results suggest that the degradation of unnecessary cellular components by autophagy is essential for maintenance of the architecture and function of beta-cells. Autophagy also serves as a crucial element of stress responses to protect beta-cells under insulin-resistant states. Impairment of autophagic machinery could thus predispose individuals to type 2 diabetes. PMID:19158492

  8. The reprogrammed pancreatic progenitor-like intermediate state of hepatic cells is more susceptible to pancreatic beta cell differentiation.

    PubMed

    Wang, Qiwei; Wang, Hai; Sun, Yu; Li, Shi-Wu; Donelan, William; Chang, Lung-Ji; Jin, Shouguang; Terada, Naohiro; Cheng, Henrique; Reeves, Westley H; Yang, Li-Jun

    2013-08-15

    Induced pluripotent stem cells (iPSCs) hold great promise for cell therapy. However, their low efficiency of lineage-specific differentiation and tumorigenesis severely hinder clinical translation. We hypothesized that reprogramming of somatic cells into lineage-specific progenitor cells might allow for large-scale expansion, avoiding the tumorigenesis inherent with iPSCs and simultaneously facilitating lineage-specific differentiation. Here we aimed at reprogramming rat hepatic WB cells, using four Yamanaka factors, into pancreatic progenitor cells (PPCs) or intermediate (IM) cells that have characteristics of PPCs. IM clones were selected based on their specific morphology and alkaline phosphatase activity and stably passaged under defined culture conditions. IM cells did not have iPSC properties, could be stably expanded in large quantity, and expressed all 14 genes that are used to define the PPC developmental stage. Directed differentiation of IM and WB cells by Pdx1-Ngn3-MafA (PNM) into pancreatic beta-like cells revealed that the IM cells are more susceptible to directed beta cell differentiation because of their open chromatin configuration, as demonstrated by expression of key pancreatic beta cell genes, secretion of insulin in response to glucose stimulation, and easy access to exogenous PNM proteins at the rat insulin 1 and Pdx1 promoters. This notion that IM cells are superior to their parental cells is further supported by the epigenetic demonstration of accessibility of Pdx1 and insulin 1 promoters. In conclusion, we have developed a strategy to derive and expand PPC cells from hepatic WB cells using conventional cell reprogramming. This proof-of-principal study may offer a novel, safe and effective way to generate autologous pancreatic beta cells for cell therapy of diabetes. PMID:23750005

  9. Cell therapies for pancreatic beta-cell replenishment.

    PubMed

    Okere, Bernard; Lucaccioni, Laura; Dominici, Massimo; Iughetti, Lorenzo

    2016-01-01

    The current treatment approach for type 1 diabetes is based on daily insulin injections, combined with blood glucose monitoring. However, administration of exogenous insulin fails to mimic the physiological activity of the islet, therefore diabetes often progresses with the development of serious complications such as kidney failure, retinopathy and vascular disease. Whole pancreas transplantation is associated with risks of major invasive surgery along with side effects of immunosuppressive therapy to avoid organ rejection. Replacement of pancreatic beta-cells would represent an ideal treatment that could overcome the above mentioned therapeutic hurdles. In this context, transplantation of islets of Langerhans is considered a less invasive procedure although long-term outcomes showed that only 10 % of the patients remained insulin independent five years after the transplant. Moreover, due to shortage of organs and the inability of islet to be expanded ex vivo, this therapy can be offered to a very limited number of patients. Over the past decade, cellular therapies have emerged as the new frontier of treatment of several diseases. Furthermore the advent of stem cells as renewable source of cell-substitutes to replenish the beta cell population, has blurred the hype on islet transplantation. Breakthrough cellular approaches aim to generate stem-cell-derived insulin producing cells, which could make diabetes cellular therapy available to millions. However, to date, stem cell therapy for diabetes is still in its early experimental stages. This review describes the most reliable sources of stem cells that have been developed to produce insulin and their most relevant experimental applications for the cure of diabetes. PMID:27400873

  10. Evidence for glucagon-like peptide-1 receptor signaling to activate ATP-sensitive potassium channels in pancreatic beta cells.

    PubMed

    Kwon, Hye-Jung; Park, Hyun-Sun; Park, Sung-Hee; Park, Jae-Hyung; Shin, Su-Kyung; Song, Seung Eun; Hwang, Meeyul; Cho, Ho-Chan; Song, Dae-Kyu

    2016-01-01

    Glucagon-like peptide-1 (GLP-1) is a gut peptide that promotes insulin release from pancreatic beta cells. GLP-1 has been shown to confer glucose-insensitive beta cells with glucose sensitivity by modulation of the activity of the ATP-sensitive potassium (KATP) channel. The channel closing effect of GLP-1, interacting with corresponding G-protein-coupled receptors, has been well established; however, to our knowledge, no study has shown whether GLP-1 directly induces activation of beta-cell KATP channels. Here, we aimed to evaluate whether the activation of beta-cell KATP channels by GLP-1 exists and affects intracellular Ca(2+) levels ([Ca(2+)]i). KATP channel activity was measured in isolated rat pancreatic beta cells by whole-cell perforated patch-clamp recordings with a diazoxide-containing pipette solution. Changes in [Ca(2+)]i and the subcellular localization of KATP channels were observed using the calcium-sensitive dye fura-4/AM and anti-Kir6.2 antibodies in INS-1 beta cells, respectively. To eliminate the well-known inhibitory effects of GLP-1 on KATP channel activity, channels were fully inhibited by pretreatment with methyl pyruvate and epigallocatechin-3-gallate. In the pretreated beta cells, GLP-1 and exendin-4 promptly activated the channels, reducing [Ca(2+)]i. The phosphoinositide 3-kinase (PI3K) inhibitor LY294002 blocked the effects of GLP-1 on channel activity. Moreover, phosphatidylinositol-3,4,5-trisphosphate mimicked the effects of GLP-1. These results suggested that beta-cell GLP-1 receptor signaling involved activation of KATP channels via a PI3K-dependent pathway. This alternative mechanism of GLP-1 function may act as a negative feedback pathway, modulating the glucose-dependent GLP-1 inhibition on KATP channel activity. PMID:26655814

  11. Induction of human pancreatic beta cell replication by inhibitors of dual specificity tyrosine regulated kinase

    PubMed Central

    Wang, Peng; Alvarez-Perez, Juan-Carlos; Felsenfeld, Dan P.; Liu, Hongtao; Sivendran, Sharmila; Bender, Aaron; Kumar, Anil; Sanchez, Roberto; Scott, Donald K.; Garcia-Ocaña, Adolfo; Stewart, Andrew F.

    2015-01-01

    Types 1 and 2 diabetes affect some 380 million people worldwide. Both result ultimately from a deficiency of functional pancreatic insulin-producing beta cells. Beta cells proliferate in humans during a brief temporal window beginning around the time of birth, with peak beta cell labeling indices achieving approximately 2% in first year of life1-4. In embryonic life and after early childhood, beta cell replication rates are very low. While beta cell expansion seems an obvious therapeutic approach to beta cell deficiency, adult human beta cells have proven recalcitrant to such efforts1-8. Hence, there remains an urgent need for diabetes therapeutic agents that can induce regeneration and expansion of adult human beta cells in vivo or ex vivo. Here, we report the results of a high-throughput small molecule screen (HTS) revealing a novel class of human beta cell mitogenic compounds, analogues of the small molecule, harmine. We also define dual specificity tyrosine-regulated kinase-1a (DYRK1A) as the likely target of harmine, and the Nuclear Factors of activated T-cells (NFAT) family of transcription factors as likely mediators of human beta cell proliferation as well as beta cell differentiation. These observations suggest that harmine analogues (“harmalogs”) may have unique therapeutic promise for human diabetes therapy. Enhancing potency and beta cell specificity are important future challenges. PMID:25751815

  12. Radioiodinated Naphthylalanine Derivatives Targeting Pancreatic Beta Cells in Normal and Nonobese Diabetic Mice

    PubMed Central

    Amartey, John K.; Shi, Yufei; Al-Jammaz, Ibrahim; Esguerra, Celestina; Al-Otaibi, Basem; Al-Mohanna, Futwan

    2008-01-01

    An imaging method capable of using a signal from pancreatic beta cells to determine their mass would be of immense value in monitoring the progression of diabetes as well as response to treatment. Somatostatin receptors (SSTRs) are expressed on beta cells and are a potential target for imaging. The main objective of this study was to investigate whether pancreatic beta cells are a target for radiolabeled naphthylalanine derivatives. The molecules were subjected to in vitro and ex vivo evaluations. Pancreatic uptake of radioactivity was lower in nonobese diabetic (NOD) mice than normal mice at all time points investigated (P < .05) and correlated with the number of islets in tissue sections of both control and NOD mice. Immunohistochemical and confocal fluorescent microscopic studies showed colocalization of insulin and the conjugate radioligand in the pancreas. The results demonstrated that pancreatic uptake is receptor-mediated, and that beta cells are the primary target. PMID:18483609

  13. Pancreatic beta cell function in the fetal pig and sow.

    PubMed

    Fowden, A L; Comline, R S; Silver, M

    1982-04-01

    Insulin secretion was investigated in acutely anaesthetized and chronically catheterized sows and their fetuses during late gestation. In the conscious animals, the mean fetal concentration of plasma insulin was 8.4 +/- 1.5 microunits/ml which was significantly less than the corresponding maternal value of 33.9 +/- 6.5 microunits/ml (n = 12, P less than 0.01). The plasma concentrations of insulin and glucose in the new-born piglets from these litters were not significantly different from the values observed in utero. The plasma concentration of insulin in the anaesthetized fetuses was significantly less than that in the chronically catheterized piglets over the same range of glucose levels. In the chronically catheterized animals, both fetal and maternal levels of insulin rose with increasing concentrations of plasma glucose while under acute conditions there was no correlation between the endogenous concentrations of insulin and glucose in either the fetuses or their mothers. Infusion of exogenous glucose (0.5 g as a 50% solution in 0.9% NaCl) stimulated the release of insulin in all the chronically catheterized fetuses studied but rarely increased the concentration of insulin in the anaesthetized fetusus. The present findings show that anaesthesia and surgery depress pancreatic beta cell function in the pig, particularly in the fetus. PMID:7043523

  14. Cocoa Phenolic Extract Protects Pancreatic Beta Cells against Oxidative Stress

    PubMed Central

    Martín, María Ángeles; Ramos, Sonia; Cordero-Herrero, Isabel; Bravo, Laura; Goya, Luis

    2013-01-01

    Diabetes mellitus is associated with reductions in glutathione, supporting the critical role of oxidative stress in its pathogenesis. Antioxidant food components such as flavonoids have a protective role against oxidative stress-induced degenerative and age-related diseases. Flavonoids constitute an important part of the human diet; they can be found in most plant foods, including green tea, grapes or cocoa and possess multiple biological activities. This study investigates the chemo-protective effect of a cocoa phenolic extract (CPE) containing mainly flavonoids against oxidative stress induced by tert-butylhydroperoxide (t-BOOH) on Ins-1E pancreatic beta cells. Cell viability and oxidative status were evaluated. Ins-1E cells treatment with 5–20 μg/mL CPE for 20 h evoked no cell damage and did not alter ROS production. Addition of 50 μM t-BOOH for 2 h increased ROS and carbonyl groups content and decreased reduced glutathione level. Pre-treatment of cells with CPE significantly prevented the t-BOOH-induced ROS and carbonyl groups and returned antioxidant defences to adequate levels. Thus, Ins-1E cells treated with CPE showed a remarkable recovery of cell viability damaged by t-BOOH, indicating that integrity of surviving machineries in the CPE-treated cells was notably protected against the oxidative insult. PMID:23912326

  15. Cell-type, allelic, and genetic signatures in the human pancreatic beta cell transcriptome.

    PubMed

    Nica, Alexandra C; Ongen, Halit; Irminger, Jean-Claude; Bosco, Domenico; Berney, Thierry; Antonarakis, Stylianos E; Halban, Philippe A; Dermitzakis, Emmanouil T

    2013-09-01

    Elucidating the pathophysiology and molecular attributes of common disorders as well as developing targeted and effective treatments hinges on the study of the relevant cell type and tissues. Pancreatic beta cells within the islets of Langerhans are centrally involved in the pathogenesis of both type 1 and type 2 diabetes. Describing the differentiated state of the human beta cell has been hampered so far by technical (low resolution microarrays) and biological limitations (whole islet preparations rather than isolated beta cells). We circumvent these by deep RNA sequencing of purified beta cells from 11 individuals, presenting here the first characterization of the human beta cell transcriptome. We perform the first comparison of gene expression profiles between beta cells, whole islets, and beta cell depleted islet preparations, revealing thus beta-cell-specific expression and splicing signatures. Further, we demonstrate that genes with consistent increased expression in beta cells have neuronal-like properties, a signal previously hypothesized. Finally, we find evidence for extensive allelic imbalance in expression and uncover genetic regulatory variants (eQTLs) active in beta cells. This first molecular blueprint of the human beta cell offers biological insight into its differentiated function, including expression of key genes associated with both major types of diabetes. PMID:23716500

  16. Unraveling the contribution of pancreatic beta-cell suicide in autoimmune type 1 diabetes✩

    PubMed Central

    Jaberi-Douraki, Majid; Schnell, Santiago; Pietropaolo, Massimo; Khadra, Anmar

    2014-01-01

    In type 1 diabetes, an autoimmune disease mediated by autoreactive T-cells that attack insulin-secreting pancreatic beta-cells, it has been suggested that disease progression may additionally require protective mechanisms in the target tissue to impede such auto-destructive mechanisms. We hypothesize that the autoimmune attack against beta-cells causes endoplasmic reticulum stress by forcing the remaining beta-cells to synthesize and secrete defective insulin. To rescue beta-cell from the endoplasmic reticulum stress, beta-cells activate the unfolded protein response to restore protein homeostasis and normal insulin synthesis. Here we investigate the compensatory role of unfolded protein response by developing a multi-state model of type 1 diabetes that takes into account beta-cell destruction caused by pathogenic autoreactive T-cells and apoptosis triggered by endoplasmic reticulum stress. We discuss the mechanism of unfolded protein response activation and how it counters beta-cell extinction caused by an autoimmune attack and/or irreversible damage by endoplasmic reticulum stress. Our results reveal important insights about the balance between beta-cell destruction by autoimmune attack (beta-cell homicide) and beta-cell apoptosis by endoplasmic reticulum stress (beta-cell suicide). It also provides an explanation as to why the unfolded protein response may not be a successful therapeutic target to treat type 1 diabetes. PMID:24831415

  17. Influence and timing of arrival of murine neural crest on pancreatic beta cell development and maturation.

    PubMed

    Plank, Jennifer L; Mundell, Nathan A; Frist, Audrey Y; LeGrone, Alison W; Kim, Thomas; Musser, Melissa A; Walter, Teagan J; Labosky, Patricia A

    2011-01-15

    Interactions between cells from the ectoderm and mesoderm influence development of the endodermally-derived pancreas. While much is known about how mesoderm regulates pancreatic development, relatively little is understood about how and when the ectodermally-derived neural crest regulates pancreatic development and specifically, beta cell maturation. A previous study demonstrated that signals from the neural crest regulate beta cell proliferation and ultimately, beta cell mass. Here, we expand on that work to describe timing of neural crest arrival at the developing pancreatic bud and extend our knowledge of the non-cell autonomous role for neural crest derivatives in the process of beta cell maturation. We demonstrated that murine neural crest entered the pancreatic mesenchyme between the 26 and 27 somite stages (approximately 10.0 dpc) and became intermingled with pancreatic progenitors as the epithelium branched into the surrounding mesenchyme. Using a neural crest-specific deletion of the Forkhead transcription factor Foxd3, we ablated neural crest cells that migrate to the pancreatic primordium. Consistent with previous data, in the absence of Foxd3, and therefore the absence of neural crest cells, proliferation of insulin-expressing cells and insulin-positive area are increased. Analysis of endocrine cell gene expression in the absence of neural crest demonstrated that, although the number of insulin-expressing cells was increased, beta cell maturation was significantly impaired. Decreased MafA and Pdx1 expression illustrated the defect in beta cell maturation; we discovered that without neural crest, there was a reduction in the percentage of insulin-positive cells that co-expressed Glut2 and Pdx1 compared to controls. In addition, transmission electron microscopy analyses revealed decreased numbers of characteristic insulin granules and the presence of abnormal granules in insulin-expressing cells from mutant embryos. Together, these data demonstrate that

  18. Influence and timing of arrival of murine neural crest on pancreatic beta cell development and maturation

    PubMed Central

    Plank, Jennifer L.; Mundell, Nathan A.; Frist, Audrey Y.; LeGrone, Alison W.; Kim, Thomas; Musser, Melissa A.; Walter, Teagan J.; Labosky, Patricia A.

    2010-01-01

    Interactions between cells from the ectoderm and mesoderm influence development of the endodermally-derived pancreas. While much is known about how mesoderm regulates pancreatic development, relatively little is understood about how and when the ectodermally-derived neural crest regulates pancreatic development and specifically, beta cell maturation. A previous study demonstrated that signals from the neural crest regulate beta cell proliferation and ultimately, beta cell mass. Here, we expand on that work to describe timing of neural crest arrival at the developing pancreatic bud and extend our knowledge of the non-cell autonomous role for neural crest derivatives in the process of beta cell maturation. We demonstrated that murine neural crest entered the pancreatic mesenchyme between the 26 and 27 somite stages (approximately 10.0 dpc) and became intermingled with pancreatic progenitors as the epithelium branched into the surrounding mesenchyme. Using a neural crest-specific deletion of the Forkhead transcription factor Foxd3, we ablated neural crest cells that migrate to the pancreatic primordium. Consistent with previous data, in the absence of Foxd3, and therefore the absence of neural crest cells, proliferation of Insulin-expressing cells and Insulin-positive area are increased. Analysis of endocrine cell gene expression in the absence of neural crest demonstrated that, although the number of Insulin-expressing cells was increased, beta cell maturation was significantly impaired. Decreased MafA and Pdx1 expression illustrated the defect in beta cell maturation; we discovered that without neural crest, there was a reduction in the percentage of Insulin-positive cells that co-expressed Glut2 and Pdx1 compared to controls. In addition, transmission electron microscopy analyses revealed decreased numbers of characteristic Insulin granules and the presence of abnormal granules in Insulin-expressing cells from mutant embryos. Together, these data demonstrate that

  19. Glucose activates prenyltransferases in pancreatic islet {beta}-cells

    SciTech Connect

    Goalstone, Marc; Kamath, Vasudeva; Kowluru, Anjaneyulu

    2010-01-01

    A growing body of evidence implicates small G-proteins [e.g., Cdc42 and Rac1] in glucose-stimulated insulin secretion [GSIS] in the islet {beta}-cell. These signaling proteins undergo post-translational modifications [e.g., prenylation] at their C-terminal cysteine residue and appear to be essential for the transport and fusion of insulin-containing secretory granules with the plasma membrane and the exocytotic secretion of insulin. However, potential regulation of the prenylating enzymes by physiological insulin secretogues [e.g., glucose] has not been investigated thus far. Herein, we report immunological localization, sub-cellular distribution and regulation of farnesyltransferases [FTases] and geranylgeranyltransferase [GGTase] by glucose in insulin-secreting INS 832/13 {beta}-cells and normal rat islets. Our findings suggest that an insulinotropic concentration of glucose [20 mM] markedly stimulated the expression of the {alpha}-subunits of FTase/GGTase-1, but not the {beta}-subunits of FTase or GGTase-1 without significantly affecting the predominantly cytosolic distribution of these holoenzymes in INS 832/13 cells and rodent islets. Under these conditions, glucose significantly stimulated [2.5- to 4.0-fold over basal] the activities of both FTase and GGTase-1 in both cell types. Together, these findings provide the first evidence to suggest that GSIS involves activation of the endogenous islet prenyltransferases by glucose, culminating in the activation of their respective G-protein substrates, which is necessary for cytoskeletal rearrangement, vesicular transport, fusion and secretion of insulin.

  20. Phenylpropenoic Acid Glucoside from Rooibos Protects Pancreatic Beta Cells against Cell Death Induced by Acute Injury

    PubMed Central

    Himpe, Eddy; Cunha, Daniel A.; Song, Imane; Bugliani, Marco; Marchetti, Piero; Cnop, Miriam; Bouwens, Luc

    2016-01-01

    Objective Previous studies demonstrated that a phenylpropenoic acid glucoside (PPAG) from rooibos (Aspalathus linearis) extract had anti-hyperglycemic activity and significant protective effects on the pancreatic beta cell mass in a chronic diet-induced diabetes model. The present study evaluated the cytoprotective effect of the phytochemical on beta cells exposed to acute cell stress. Methods Synthetically prepared PPAG was administered orally in mice treated with a single dose of streptozotocin to acutely induce beta cell death and hyperglycemia. Its effect was assessed on beta cell mass, proliferation and apoptotic cell death. Its cytoprotective effect was also studied in vitro on INS-1E beta cells and on human pancreatic islet cells. Results Treatment with the phytochemical PPAG protected beta cells during the first days after the insult against apoptotic cell death, as evidenced by TUNEL staining, and prevented loss of expression of anti-apoptotic protein BCL2 in vivo. In vitro, PPAG protected INS-1E beta cells from streptozotocin-induced apoptosis and necrosis in a BCL2-dependent and independent way, respectively, depending on glucose concentration. PPAG also protected human pancreatic islet cells against the cytotoxic action of the fatty acid palmitate. Conclusions These findings show the potential use of PPAG as phytomedicine which protects the beta cell mass exposed to acute diabetogenic stress. PMID:27299564

  1. Update on the protective molecular pathways improving pancreatic beta-cell dysfunction.

    PubMed

    Puddu, Alessandra; Sanguineti, Roberta; Mach, François; Dallegri, Franco; Viviani, Giorgio Luciano; Montecucco, Fabrizio

    2013-01-01

    The primary function of pancreatic beta-cells is to produce and release insulin in response to increment in extracellular glucose concentrations, thus maintaining glucose homeostasis. Deficient beta-cell function can have profound metabolic consequences, leading to the development of hyperglycemia and, ultimately, diabetes mellitus. Therefore, strategies targeting the maintenance of the normal function and protecting pancreatic beta-cells from injury or death might be crucial in the treatment of diabetes. This narrative review will update evidence from the recently identified molecular regulators preserving beta-cell mass and function recovery in order to suggest potential therapeutic targets against diabetes. This review will also highlight the relevance for novel molecular pathways potentially improving beta-cell dysfunction. PMID:23737653

  2. Transcriptome landmarks of the functional maturity of rat beta-cells, from lactation to adulthood.

    PubMed

    Larqué, Carlos; Velasco, Myrian; Barajas-Olmos, Francisco; García-Delgado, Neyvis; Chávez-Maldonado, Juan Pablo; García-Morales, Jazmín; Orozco, Lorena; Hiriart, Marcia

    2016-07-01

    Research on the postnatal development of pancreatic beta-cells has become an important subject in recent years. Understanding the mechanisms that govern beta-cell postnatal maturation could bring new opportunities to therapeutic approaches for diabetes. The weaning period consists of a critical postnatal window for structural and physiologic maturation of rat beta-cells. To investigate transcriptome changes involved in the maturation of beta-cells neighboring this period, we performed microarray analysis in fluorescence-activated cell-sorted (FACS) beta-cell-enriched populations. Our results showed a variety of gene sets including those involved in the integration of metabolism, modulation of electrical activity, and regulation of the cell cycle that play important roles in the maturation process. These observations were validated using reverse hemolytic plaque assay, electrophysiological recordings, and flow cytometry analysis. Moreover, we suggest some unexplored pathways such as sphingolipid metabolism, insulin-vesicle trafficking, regulation of transcription/transduction by miRNA-30, trafficking proteins, and cell cycle proteins that could play important roles in the process mentioned above for further investigation. PMID:27220619

  3. Pancreatic beta cells express a diverse set of homeobox genes.

    PubMed Central

    Rudnick, A; Ling, T Y; Odagiri, H; Rutter, W J; German, M S

    1994-01-01

    Homeobox genes, which are found in all eukaryotic organisms, encode transcriptional regulators involved in cell-type differentiation and development. Several homeobox genes encoding homeodomain proteins that bind and activate the insulin gene promoter have been described. In an attempt to identify additional beta-cell homeodomain proteins, we designed primers based on the sequences of beta-cell homeobox genes cdx3 and lmx1 and the Drosophila homeodomain protein Antennapedia and used these primers to amplify inserts by PCR from an insulinoma cDNA library. The resulting amplification products include sequences encoding 10 distinct homeodomain proteins; 3 of these proteins have not been described previously. In addition, an insert was obtained encoding a splice variant of engrailed-2, a homeodomain protein previously identified in the central nervous system. Northern analysis revealed a distinct pattern of expression for each homeobox gene. Interestingly, the PCR-derived clones do not represent a complete sampling of the beta-cell library because no inserts encoding cdx3 or lmx1 protein were obtained. Beta cells probably express additional homeobox genes. The abundance and diversity of homeodomain proteins found in beta cells illustrate the remarkable complexity and redundancy of the machinery controlling beta-cell development and differentiation. Images PMID:7991607

  4. A role for G(z) in pancreatic islet beta-cell biology.

    PubMed

    Kimple, Michelle E; Nixon, Andrew B; Kelly, Patrick; Bailey, Candice L; Young, Kenneth H; Fields, Timothy A; Casey, Patrick J

    2005-09-01

    Glucose-stimulated insulin secretion and beta-cell growth are important facets of pancreatic islet beta-cell biology. As a result, factors that modulate these processes are of great interest for the potential treatment of Type 2 diabetes. Here, we present evidence that the heterotrimeric G protein G(z) and its effectors, including some previously thought to be confined in expression to neuronal cells, are present in pancreatic beta-cells, the largest cellular constituent of the islets of Langerhans. Furthermore, signaling pathways upon which G alpha(z) impacts are intact in beta-cells, and G alpha(z) activation inhibits both cAMP production and glucose-stimulated insulin secretion in the Ins-1(832/13) beta-cell-derived line. Inhibition of glucose-stimulated insulin secretion by prostaglandin E (PGE1) is pertussis-toxin insensitive, indicating that other G alpha(i) family members are not involved in this process in this beta-cell line. Indeed, overexpression of a selective deactivator of G alpha(z), the RGS domain of RGSZ1, blocks the inhibitory effect of PGE1 on glucose-stimulated insulin secretion. Finally, the inhibition of glucose-stimulated insulin secretion by PGE1 is substantially blunted by small interfering RNA-mediated knockdown of G alpha(z) expression. Taken together, these data strongly imply that the endogenous E prostanoid receptor in the Ins-1(832/13) beta-cell line couples to G(z) predominantly and perhaps even exclusively. These data provide the first evidence for G(z) signaling in pancreatic beta-cells, and identify an endogenous receptor-mediated signaling process in beta-cells that is dependent on G alpha(z) function. PMID:16157560

  5. Plant-Derived Compounds Targeting Pancreatic Beta Cells for the Treatment of Diabetes

    PubMed Central

    Oh, Yoon Sin

    2015-01-01

    Diabetes is a global health problem and a national economic burden. Although several antidiabetic drugs are available, the need for novel therapeutic agents with improved efficacy and few side effects remains. Drugs derived from natural compounds are more attractive than synthetic drugs because of their diversity and minimal side effects. This review summarizes the most relevant effects of various plant-derived natural compounds on the functionality of pancreatic beta cells. Published data suggest that natural compounds directly enhance insulin secretion, prevent pancreatic beta cell apoptosis, and modulate pancreatic beta cell differentiation and proliferation. It is essential to continuously investigate natural compounds as sources of novel pharmaceuticals. Therefore, more studies into these compounds' mechanisms of action are warranted for their development as potential anti-diabetics. PMID:26587047

  6. Ryanodine receptors are involved in nuclear calcium oscillation in primary pancreatic {beta}-cells

    SciTech Connect

    Zheng, Ji; Chen, Zheng; Yin, Wenxuan; Miao, Lin; Zhou, Zhansong; Ji, Guangju

    2012-06-29

    Highlights: Black-Right-Pointing-Pointer We found that RyRs are expressed on the nuclear envelope in single primary pancreatic {beta}-cells and isolated nuclei. Black-Right-Pointing-Pointer We showed that the pattern of glucose-induced Ca{sup 2+} oscillation in the nucleus and cytosol was similar. Black-Right-Pointing-Pointer Our results demonstrate that ryanodine-sensitive Ca{sup 2+} stores exist and have function in the pancreatic {beta}-cell nucleus. -- Abstract: Ryanodine receptors (RyRs) are mainly located on the endoplasmic reticulum (ER) and play an important role in regulating glucose-induced cytosolic Ca{sup 2+} oscillation in pancreatic {beta}-cells. However, subcellular locations and functions of RyRs on other cell organelles such as nuclear envelope are not well understood. In order to investigate the role of RyRs in nuclear Ca{sup 2+} oscillation we designed and conducted experiments in intact primary pancreatic {beta}-cells. Immunocytochemistry was used to examine the expression of RYRs on the nuclear envelope. Confocal microscopy was used to evaluate the function of RYRs on the nuclear envelope. We found that RyRs are expressed on the nuclear envelope in single primary pancreatic {beta}-cells and isolated nuclei. Laser scanning confocal microscopy studies indicated that application of glucose to the cells co-incubated with Ca{sup 2+} indicator Fluo-4 AM and cell-permeable nuclear indicator Hoechst 33342 resulted in nuclear Ca{sup 2+} oscillation. The pattern of glucose-induced Ca{sup 2+} oscillation in the nucleus and cytosol was similar. The reduction of Ca{sup 2+} oscillation amplitude by ryanodine was much greater in the nucleus though both the cytosol and the nucleus Ca{sup 2+} amplitude decreased by ryanodine. Our results suggest that functional ryanodine receptors not only exist in endoplasmic reticulum but are also expressed in nuclear envelope of pancreatic {beta}-cells.

  7. On the coherent behavior of pancreatic beta cell clusters

    NASA Astrophysics Data System (ADS)

    Loppini, Alessandro; Capolupo, Antonio; Cherubini, Christian; Gizzi, Alessio; Bertolaso, Marta; Filippi, Simonetta; Vitiello, Giuseppe

    2014-09-01

    Beta cells in pancreas represent an example of coupled biological oscillators which via communication pathways, are able to synchronize their electrical activity, giving rise to pulsatile insulin release. In this work we numerically analyze scale free self-similarity features of membrane voltage signal power density spectrum, through a stochastic dynamical model for beta cells in the islets of Langerhans fine tuned on mouse experimental data. Adopting the algebraic approach of coherent state formalism, we show how coherent molecular domains can arise from proper functional conditions leading to a parallelism with “phase transition” phenomena of field theory.

  8. The expression and function of histamine H3 receptors in pancreatic beta cells

    PubMed Central

    Nakamura, T; Yoshikawa, T; Noguchi, N; Sugawara, A; Kasajima, A; Sasano, H; Yanai, K

    2014-01-01

    BACKGROUND AND PURPOSE Histamine and its receptors in the CNS play important roles in energy homeostasis. Here, we have investigated the expression and role of histamine receptors in pancreatic beta cells, which secrete insulin. EXPERIMENTAL APPROACH The expression of histamine receptors in pancreatic beta cells was examined by RT-PCR, Western blotting and immunostaining. Insulin secretion assay, ATP measurement and calcium imaging studies were performed to determine the function and signalling pathway of histamine H3 receptors in glucose-induced insulin secretion (GIIS) from MIN6 cells, a mouse pancreatic beta cell line. The function and signalling pathway of H3 receptors in MIN6 cell proliferation were examined using pharmacological assay and Western blotting. KEY RESULTS Histamine H3 receptors were expressed in pancreatic beta cells. A selective H3 receptor agonist, imetit, and a selective inverse H3 receptor agonist, JNJ-5207852, had inhibitory and facilitatory effects, respectively, on GIIS in MIN6 cells. Neither imetit nor JNJ-5207852 altered intracellular ATP concentration, or intracellular calcium concentration stimulated by glucose and KCl, indicating that GIIS signalling was affected by H3 receptor signalling downstream of the increase in intracellular calcium concentration. Moreover, imetit attenuated bromodeoxyuridine incorporation in MIN6 cells. The phosphorylation of cAMP response element-binding protein (CREB), which facilitated beta cell proliferation, was inhibited, though not significantly, by imetit, indicating that activated H3 receptors inhibited MIN6 cell proliferation, possibly by decreasing CREB phosphorylation. CONCLUSIONS AND IMPLICATIONS Histamine H3 receptors were expressed in mouse beta cells and could play a role in insulin secretion and, possibly, beta cell proliferation. PMID:24117016

  9. ROS signaling, oxidative stress and Nrf2 in pancreatic beta-cell function

    SciTech Connect

    Pi Jingbo; Zhang Qiang; Fu Jingqi; Woods, Courtney G.; Hou Yongyong; Corkey, Barbara E.; Collins, Sheila; Andersen, Melvin E.

    2010-04-01

    This review focuses on the emerging evidence that reactive oxygen species (ROS) derived from glucose metabolism, such as H{sub 2}O{sub 2}, act as metabolic signaling molecules for glucose-stimulated insulin secretion (GSIS) in pancreatic beta-cells. Particular emphasis is placed on the potential inhibitory role of endogenous antioxidants, which rise in response to oxidative stress, in glucose-triggered ROS and GSIS. We propose that cellular adaptive response to oxidative stress challenge, such as nuclear factor E2-related factor 2 (Nrf2)-mediated antioxidant induction, plays paradoxical roles in pancreatic beta-cell function. On the one hand, induction of antioxidant enzymes protects beta-cells from oxidative damage and possible cell death, thus minimizing oxidative damage-related impairment of insulin secretion. On the other hand, the induction of antioxidant enzymes by Nrf2 activation blunts glucose-triggered ROS signaling, thus resulting in reduced GSIS. These two premises are potentially relevant to impairment of beta-cells occurring in the late and early stage of Type 2 diabetes, respectively. In addition, we summarized our recent findings that persistent oxidative stress due to absence of uncoupling protein 2 activates cellular adaptive response which is associated with impaired pancreatic beta-cell function.

  10. Pituitary tumor transforming gene-null male mice exhibit impaired pancreatic beta cell proliferation and diabetes

    PubMed Central

    Wang, Zhiyong; Moro, Enrico; Kovacs, Kalman; Yu, Run; Melmed, Shlomo

    2003-01-01

    The mammalian securin, pituitary tumor transforming gene (PTTG), regulates sister chromatid separation during mitosis. Mice or cell lines deficient in PTTG expression, however, are surprisingly viable. Here we show that PTTG disruption in mice (PTTG−/−) severely impairs glucose homeostasis leading to diabetes during late adulthood, especially in males associated with nonautoimmune insulinopenia and reversed alpha/beta cell ratio. Islet beta cell mass in PTTG−/− mice was already diminished before development of frank diabetes and only increased minimally during growth. BrdUrd incorporation of islet cells in PTTG-null mice was ≈65% lower (P < 0.005) than in the WT pancreas, whereas apoptosis rates were similar. PTTG−/− beta cells had pleiotropic nuclei, suggesting defects in cell division. The results indicated that securin is indispensable for normal pancreatic beta cell proliferation. PMID:12626748

  11. Generating pancreatic beta-cells from embryonic stem cells by manipulating signaling pathways.

    PubMed

    Champeris Tsaniras, Spyridon; Jones, Peter M

    2010-07-01

    Type 1 diabetes results from an insufficiency of insulin production as a result of autoimmune destruction of the insulin-secreting pancreatic beta-cells. It can be treated by transplantation of islets of Langerhans from human donors, but widespread application of this therapy is restricted by the scarcity of donor tissue. Generation of functional beta-cells from embryonic stem (ES) cells in vitro could provide a source of an alternative graft material. Several ES cell differentiation protocols have reported the production of insulin-producing cells by mimicking the in vivo developmental stages of pancreatic organogenesis in which cells are transitioned through mesendoderm, definitive endoderm, foregut endoderm, pancreatic endoderm, and the endocrine precursor stage, until mature beta-cells are obtained. These studies provide proof of concept that recapitulating pancreatic development in vitro offers a useful strategy for generating beta-cells, but current differentiation protocols employ a bewildering variety of growth factors, mitogens, and pharmacological agents. In this review, we will attempt to clarify the functions of these agents in in vitro differentiation strategies by focusing on the intracellular signaling pathways through which they operate - phosphatidylinositol 3-kinase, transforming growth factor beta, Wnt/beta-catenin, Hedgehog, and Notch. PMID:20385725

  12. Pigment epithelium-derived factor (PEDF) regulates metabolism and insulin secretion from a clonal rat pancreatic beta cell line BRIN-BD11 and mouse islets.

    PubMed

    Chen, Younan; Carlessi, Rodrigo; Walz, Nikita; Cruzat, Vinicius Fernandes; Keane, Kevin; John, Abraham N; Jiang, Fang-Xu; Carnagarin, Revathy; Dass, Crispin R; Newsholme, Philip

    2016-05-01

    Pigment epithelium-derived factor (PEDF) is a multifunctional glycoprotein, associated with lipid catabolism and insulin resistance. In the present study, PEDF increased chronic and acute insulin secretion in a clonal rat β-cell line BRIN-BD11, without alteration of glucose consumption. PEDF also stimulated insulin secretion from primary mouse islets. Seahorse flux analysis demonstrated that PEDF did not change mitochondrial respiration and glycolytic function. The cytosolic presence of the putative PEDF receptor - adipose triglyceride lipase (ATGL) - was identified, and ATGL associated stimulation of glycerol release was robustly enhanced by PEDF, while intracellular ATP levels increased. Addition of palmitate or ex vivo stimulation with inflammatory mediators induced β-cell dysfunction, effects not altered by the addition of PEDF. In conclusion, PEDF increased insulin secretion in BRIN-BD11 and islet cells, but had no impact on glucose metabolism. Thus elevated lipolysis and enhanced fatty acid availability may impact insulin secretion following PEDF receptor (ATGL) stimulation. PMID:26868448

  13. Insulin-producing cells could not mimic the physiological regulation of insulin secretion performed by pancreatic beta cells

    PubMed Central

    2013-01-01

    Objective The aim of this study was to compare the difference between insulin-producing cells (IPCs) and normal human pancreatic beta cells both in physiological function and morphological features in cellular level. Methods The levels of insulin secretion were measured by enzyme-linked immunosorbent assay. The insulin gene expression was determined by real-time quantitative polymerase chain reaction. The morphological features were detected by atomic force microscopy (AFM) and laser confocal scanning microscopy. Results IPCs and normal human pancreatic beta cells were similar to each other under the observation in AFM with the porous structure features in the cytoplasm. Both number of membrane particle size and average roughness of normal human beta cells were higher than those of IPCs. Conclusions Our results firstly revealed that the cellular ultrastructure of IPCs was closer to that of normal human pancreatic beta cells, but they still could not mimic the physiological regulation of insulin secretion performed by pancreatic beta cells. PMID:23421382

  14. [A preliminary study on the mechanism of impaired beta cell function in monosodium glutamate obese rat with insulin resistance].

    PubMed

    Liu, Shuai-Nan; Liu, Quan; Shen, Zhu-Fang

    2008-11-01

    This study is to evaluate beta cell function and investigate the mechanism of impaired pancreatic islet beta cell function in monosodium glutamate (MSG) obese rat with insulin resistance, an animal model of metabolic syndrome. Insulin tolerance test was used to screen MSG obese rats with insulin resistance. Blood concentrations of glucose, triglyceride, total cholesterol and insulin were determined. Beta cell function was assessed with hyperglycemic clamp technique. The morphological alterations in pancreas and changes of islet beta cell mass were evaluated by hematoxylin-eosin (HE) and Gomori aldehyde fuchsin staining. Lipid, oxidative stress relevant factors, nitric oxide (NO) level and activity of ATPase in pancreas and pancreatic mitochondrial were tested. The MSG obese rats with insulin resistance could be validated as a typical metabolic syndrome animal model possessing increased fasting plasma triglycerides and insulin (P < 0. 001), markedly decreased weight indices of pancreas and impaired glucose-stimulated insulin secretion. Hematoxylin-eosin (HE) and Gomori aldehyde fuchsin staining showed increased adipocytes and fibroplasia deposition in pancreas and reduced beta cell mass. The increased contents of triglyceride and NO level, the decreased SOD levels and activities of total ATPase (P < 0.001), Na+-K+-ATPase (P < 0.001) and Ca2+-Mg2+-ATPase (P < 0.01) were observed in pancreas and its mitochondria versus normal rat. The study demonstrates that accumulation of lipids in pancreas could lead to increased systemic indicators of inflammation, such as NO, which may influence the activities of several kinds of ATPase in cell membranes and interfere the ion transport, substance metabolism and energy production in pancreas. Finally the MSG obese rats characterized with metabolic syndrome displayed an impairment of beta cell function. PMID:19239028

  15. Islet-selectivity of G-protein coupled receptor ligands evaluated for PET imaging of pancreatic {beta}-cell mass

    SciTech Connect

    Cline, Gary W.; Zhao, Xiaojian; Jakowski, Amy B.; Soeller, Walter C.; Treadway, Judith L.

    2011-09-02

    Highlights: {yields} We screened G-protein coupled receptors for imaging pancreatic. {yields} Database mining and immunohistochemistry identified GPCRs enriched in {beta}-cells. {yields} In vitro and in vivo assays were used to determine exocrine vs endocrine specificity. {yields} GPCR candidates for imaging of {beta}-cell mass are Prokineticin-1R, mGluR5, and GLP-1R. -- Abstract: A critical unmet need exists for methods to quantitatively measure endogenous pancreatic {beta}-cell mass (BCM) for the clinical evaluation of therapies to prevent or reverse loss of BCM and diabetes progression. Our objective was to identify G-protein coupled receptors (GPCRs) that are expressed with a high degree of specificity to islet {beta}-cells for receptor-targeted imaging of BCM. GPCRs enriched in pancreatic islets relative to pancreas acinar and hepatic tissue were identified using a database screen. Islet-specific expression was confirmed by human pancreas immunohistochemistry (IHC). In vitro selectivity assessment was determined from the binding and uptake of radiolabeled ligands to the rat insulinoma INS-1 832/13 cell line and isolated rat islets relative to the exocrine pancreas cell-type, PANC-1. Tail-vein injections of radioligands into rats were used to determine favorable image criteria of in vivo biodistribution to the pancreas relative to other internal organs (i.e., liver, spleen, stomach, and lungs). Database and IHC screening identified four candidate receptors for further in vitro and in vivo evaluation for PET imaging of BCM: prokineticin-1 receptor (PK-1R), metabotropic glutamate receptor type-5 (mGluR5), neuropeptide Y-2 receptor (NPY-2R), and glucagon-like peptide 1 receptor (GLP-1R). In vitro specificity ratios gave the following receptor rank order: PK-1R > GLP-1R > NPY-2R > mGluR5. The biodistribution rank order of selectivity to the pancreas was found to be PK-1R > VMAT2 {approx} GLP-1R > mGluR5. Favorable islet selectivity and biodistribution

  16. Osteocalcin protects pancreatic beta cell function and survival under high glucose conditions

    SciTech Connect

    Kover, Karen; Yan, Yun; Tong, Pei Ying; Watkins, Dara; Li, Xiaoyu; Tasch, James; Hager, Melissa; Clements, Mark; Moore, Wayne V.

    2015-06-19

    Diabetes is characterized by progressive beta cell dysfunction and loss due in part to oxidative stress that occurs from gluco/lipotoxicity. Treatments that directly protect beta cell function and survival in the diabetic milieu are of particular interest. A growing body of evidence suggests that osteocalcin, an abundant non-collagenous protein of bone, supports beta cell function and proliferation. Based on previous gene expression data by microarray, we hypothesized that osteocalcin protects beta cells from glucose-induced oxidative stress. To test our hypothesis we cultured isolated rat islets and INS-1E cells in the presence of normal, high, or high glucose ± osteocalcin for up to 72 h. Oxidative stress and viability/mitochondrial function were measured by H{sub 2}O{sub 2} assay and Alamar Blue assay, respectively. Caspase 3/7 activity was also measured as a marker of apoptosis. A functional test, glucose stimulated insulin release, was conducted and expression of genes/protein was measured by qRT-PCR/western blot/ELISA. Osteocalcin treatment significantly reduced high glucose-induced H{sub 2}O{sub 2} levels while maintaining viability/mitochondrial function. Osteocalcin also significantly improved glucose stimulated insulin secretion and insulin content in rat islets after 48 h of high glucose exposure compared to untreated islets. As expected sustained high glucose down-regulated gene/protein expression of INS1 and BCL2 while increasing TXNIP expression. Interestingly, osteocalcin treatment reversed the effects of high glucose on gene/protein expression. We conclude that osteocalcin can protect beta cells from the negative effects of glucose-induced oxidative stress, in part, by reducing TXNIP expression, thereby preserving beta cell function and survival. - Highlights: • Osteocalcin reduces glucose-induced oxidative stress in beta cells. • Osteocalcin preserves beta cell function and survival under stress conditions. • Osteocalcin reduces glucose

  17. Transcription factors involved in glucose-stimulated insulin secretion of pancreatic beta cells

    SciTech Connect

    Shao, Shiying; Fang, Zhong; Yu, Xuefeng; Zhang, Muxun

    2009-07-10

    GSIS, the most important function of pancreatic beta cell, is essential for maintaining the glucose homeostasis. Transcription factors are known to control different biological processes such as differentiation, proliferation and apoptosis. In pancreas, some transcription factors are involved in regulating the function of beta cells. In this review, the role of these transcription factors including Pdx-1, FoxO1, SREBP-1c, and MafA in GSIS is highlighted. The related molecular mechanisms are analyzed as well. Furthermore, the association between the role of transcription factors in GSIS and the development of T2DM is discussed.

  18. The Microtubule-Associated Protein Tau and Its Relevance for Pancreatic Beta Cells

    PubMed Central

    Maj, Magdalena; Hoermann, Gregor; Rasul, Sazan; Base, Wolfgang; Wagner, Ludwig; Attems, Johannes

    2016-01-01

    Structural and biochemical alterations of the microtubule-associated protein tau (MAPT) are associated with degenerative disorders referred to as tauopathies. We have previously shown that MAPT is present in human islets of Langerhans, human insulinomas, and pancreatic beta-cell line models, with biophysical similarities to the pathological MAPT in the brain. Here, we further studied MAPT in pancreatic endocrine tissue to better understand the mechanisms that lead to functional dysregulation of pancreatic beta cells. We found upregulation of MAPT protein expression in human insulinomas when compared to human pancreatic islets of Langerhans and an imbalance between MAPT isoforms in insulinomas tissue. We cloned one 3-repeat domain MAPT and transduced this into a beta-cell derived rodent cell line Rin-5F. Proliferation experiments showed higher growth rates and metabolic activities of cells overexpressing MAPT protein. We observed that a MAPT overexpressing cell line demonstrates altered insulin transcription, translation, and insulin secretion rates. We found the relative insulin secretion rates were significantly decreased in a MAPT overexpressing cell line and these findings could be confirmed using partial MAPT knock-down cell lines. Our findings support that MAPT may play an important role in insulin granule trafficking and indicate the importance of balanced MAPT phosphorylation and dephosphorylation for adequate insulin release. PMID:26824039

  19. Thyrotropin releasing hormone (TRH) affects gene expression in pancreatic beta-cells.

    PubMed

    Luo, LuGuang; Yano, Naohiro

    2005-01-01

    Thyrotropin-releasing hormone (TRH), originally identified as a hypothalamic hormone, is expressed in the pancreas. The peptide has been shown to control glycemia, although the role of TRH in the pancreas has not yet been clarified. In quiescent INS-1 cells (rat immortalized beta-cell line), 200 nM of TRH for 24 hours significantly increased insulin levels in the culture medium and in cell extracts. In studies with gene array technology where about 60% to 75% of the 1081 genes were detected, TRH significantly stimulated multiple groups of gene expressions, including G-protein-coupled receptor and related signaling, such as insulin secretion, endoplasmic reticulum traffic mechanisms, cell-cycle regulators, protein turnover factors, DNA recombination, and growth factors. Noticeably, TRH suppressed the genes of proapoptotic Bcl-2-associated protein X, Bcl-xL/ Bcl-2-associated death promoter, and Fas. The multiple gene expressions in response to TRH in pancreatic cells suggest that the changed microenvironment brought about by TRH may influence beta-cellfunction. PMID:16392621

  20. Effect of Exendin-4 on Autophagy Clearance in Beta Cell of Rats with Tacrolimus-induced Diabetes Mellitus

    PubMed Central

    Lim, Sun Woo; Jin, Long; Jin, Jian; Yang, Chul Woo

    2016-01-01

    Growing evidence suggests that GLP-1 protects beta cells against various cellular injuries by modulating autophagy. In this study, we examined whether exendin-4 (Ex-4), a GLP-1 analog, had preventive effects on tacrolimus (Tac)-induced beta cell injury by improving autophagy clearance. Rats with Tac-induced diabetes mellitus exhibited increased autophagy-associated protein expression, light chain 3B levels, and autophagic vacuole numbers in pancreatic beta cells. Additionally, Tac increased autophagy in a dose- and time-dependent manner in vitro, and inhibition of autophagosome using 3-methyladenine reduced Tac-induced islet cell injury by decreasing reactive oxygen species production and apoptosis. Ex-4 treatment decreased Tac-induced hyperglycaemia, oxidative stress, and apoptosis, accompanied by decreased autophagy-associated protein expression and autophagosome numbers. In vivo and in vitro studies showed that Tac treatment impaired lysosomal function and autophagosome-lysosome fusion; these processes were improve by Ex-4 treatment. Moreover, addition of bafilomycin A1, an inhibitor of lysosomal function, abolished the protective effects of Ex-4. Our findings reveal that Tac-induced diabetes mellitus was a state of excessive burden of autophagosomes and impairment of autophagy clearance and that Ex-4 protected against Tac-induced pancreatic islet injury by reducing the burden of autophagosomes via activation of autophagosome clearance. Thus, Ex-4 had therapeutic effects on Tac-induced pancreatic beta cell injury. PMID:27436514

  1. Ataxin-10 interacts with O-GlcNAc transferase OGT in pancreatic {beta} cells

    SciTech Connect

    Andrali, Sreenath S.; Maerz, Pia; Oezcan, Sabire . E-mail: sozcan@uky.edu

    2005-11-11

    Several nuclear and cytoplasmic proteins in metazoans are modified by O-linked N-acetylglucosamine (O-GlcNAc). This modification is dynamic and reversible similar to phosphorylation and is catalyzed by the O-linked GlcNAc transferase (OGT). Hyperglycemia has been shown to increase O-GlcNAc levels in pancreatic {beta} cells, which appears to interfere with {beta}-cell function. To obtain a better understanding of the role of O-linked GlcNAc modification in {beta} cells, we have isolated OGT interacting proteins from a cDNA library made from the mouse insulinoma MIN6 cell line. We describe here the identification of Ataxin-10, encoded by the SCA10 (spinocerebellar ataxia type 10) gene as an OGT interacting protein. Mutations in the SCA10 gene cause progressive cerebellar ataxias and seizures. We demonstrate that SCA10 interacts with OGT in vivo and is modified by O-linked glycosylation in MIN6 cells, suggesting a novel role for the Ataxin-10 protein in pancreatic {beta} cells.

  2. Present and future cell therapies for pancreatic beta cell replenishment

    PubMed Central

    Domínguez-Bendala, Juan; Ricordi, Camillo

    2012-01-01

    If only at a small scale, islet transplantation has successfully addressed what ought to be the primary endpoint of any cell therapy: the functional replenishment of damaged tissue in patients. After years of less-than-optimal approaches to immunosuppression, recent advances consistently yield long-term graft survival rates comparable to those of whole pancreas transplantation. Limited organ availability is the main hurdle that stands in the way of the widespread clinical utilization of this pioneering intervention. Progress in stem cell research over the past decade, coupled with our decades-long experience with islet transplantation, is shaping the future of cell therapies for the treatment of diabetes. Here we review the most promising avenues of research aimed at generating an inexhaustible supply of insulin-producing cells for islet regeneration, including the differentiation of pluripotent and multipotent stem cells of embryonic and adult origin along the beta cell lineage and the direct reprogramming of non-endocrine tissues into insulin-producing cells. PMID:23322984

  3. The Glucotoxicity Protecting Effect of Ezetimibe in Pancreatic Beta Cells via Inhibition of CD36

    PubMed Central

    2016-01-01

    Inhibition of CD36, a fatty acid transporter, has been reported to prevent glucotoxicity and ameliorate high glucose induced beta cell dysfunction. Ezetimibe is a selective cholesterol absorption inhibitor that blocks Niemann Pick C1-like 1 protein, but may exert its effect through suppression of CD36. We attempted to clarify the beneficial effect of ezetimibe on insulin secreting cells and to determine whether this effect is related to change of CD36 expression. mRNA expression of insulin and CD36, intracellular peroxide level and glucose stimulated insulin secretion (GSIS) under normal (5.6 mM) or high glucose (30 mM) condition in INS-1 cells and primary rat islet cells were compared. Changes of the aforementioned factors with treatment with ezetimibe (20 μM) under normal or high glucose condition were also assessed. mRNA expression of insulin was decreased with high glucose, which was reversed by ezetimibe in both INS-1 cells and primary rat islets. CD36 mRNA expression was increased with high glucose, but decreased by ezetimibe in INS-1 cells and primary rat islets. Three-day treatment with high glucose resulted in an increase in intracellular peroxide level; however, it was decreased by treatment with ezetimibe. Decrease in GSIS by three-day treatment with high glucose was reversed by ezetimibe. Palmitate uptake following exposure to high glucose conditions for three days was significantly elevated, which was reversed by ezetimibe in INS-1 cells. Ezetimibe may prevent glucotoxicity in pancreatic β-cells through a decrease in fatty acid influx via inhibition of CD36. PMID:27051238

  4. The Glucotoxicity Protecting Effect of Ezetimibe in Pancreatic Beta Cells via Inhibition of CD36.

    PubMed

    Yoon, Ji Sung; Moon, Jun Sung; Kim, Yong-Woon; Won, Kyu Chang; Lee, Hyoung Woo

    2016-04-01

    Inhibition of CD36, a fatty acid transporter, has been reported to prevent glucotoxicity and ameliorate high glucose induced beta cell dysfunction. Ezetimibe is a selective cholesterol absorption inhibitor that blocks Niemann Pick C1-like 1 protein, but may exert its effect through suppression of CD36. We attempted to clarify the beneficial effect of ezetimibe on insulin secreting cells and to determine whether this effect is related to change of CD36 expression. mRNA expression of insulin and CD36, intracellular peroxide level and glucose stimulated insulin secretion (GSIS) under normal (5.6 mM) or high glucose (30 mM) condition in INS-1 cells and primary rat islet cells were compared. Changes of the aforementioned factors with treatment with ezetimibe (20 μM) under normal or high glucose condition were also assessed. mRNA expression of insulin was decreased with high glucose, which was reversed by ezetimibe in both INS-1 cells and primary rat islets. CD36 mRNA expression was increased with high glucose, but decreased by ezetimibe in INS-1 cells and primary rat islets. Three-day treatment with high glucose resulted in an increase in intracellular peroxide level; however, it was decreased by treatment with ezetimibe. Decrease in GSIS by three-day treatment with high glucose was reversed by ezetimibe. Palmitate uptake following exposure to high glucose conditions for three days was significantly elevated, which was reversed by ezetimibe in INS-1 cells. Ezetimibe may prevent glucotoxicity in pancreatic β-cells through a decrease in fatty acid influx via inhibition of CD36. PMID:27051238

  5. GLP-1 receptor antagonist as a potential probe for pancreatic {beta}-cell imaging

    SciTech Connect

    Mukai, Eri; Toyoda, Kentaro; Kimura, Hiroyuki; Kawashima, Hidekazu; Fujimoto, Hiroyuki; Ueda, Masashi; Temma, Takashi; Hirao, Konomu; Nagakawa, Kenji; Saji, Hideo; Inagaki, Nobuya

    2009-11-20

    We examined exendin(9-39), an antagonist of glucagon-like peptide-1 (GLP-1) receptor (GLP-1R), as a potential probe for imaging of pancreatic {beta}-cells. To evaluate in vitro receptor specificity, binding assay was performed using dispersed mouse islet cells. Binding assay showed competitive inhibition of [{sup 125}I]BH-exendin(9-39) binding by non-radioactive exendin(9-39). To assess in vivo selectivity, the biodistribution was evaluated by intravenous administration of [{sup 125}I]BH-exendin(9-39) to mice. Radioactivity of harvested pancreas reached highest levels at 60 and 120 min among organs examined except lung. Pre-administration of excess non-radioactive exendin(9-39) remarkably and specifically blocked the radioactivity of pancreas. After [{sup 125}I]BH-exendin(9-39) injection into transgenic mice with pancreatic {beta}-cells expressing GFP, fluorescent and radioactive signals of sections of pancreas were evaluated with an image analyzer. Imaging analysis showed that the fluorescent GFP signals and the radioactive signals were correspondingly located. Thus, the GLP-1R antagonist exendin(9-39) may serve as a useful probe for pancreatic {beta}-cell imaging.

  6. Modulation of Ionic Channels and Insulin Secretion by Drugs and Hormones in Pancreatic Beta Cells.

    PubMed

    Velasco, Myrian; Díaz-García, Carlos Manlio; Larqué, Carlos; Hiriart, Marcia

    2016-09-01

    Pancreatic beta cells, unique cells that secrete insulin in response to an increase in glucose levels, play a significant role in glucose homeostasis. Glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells has been extensively explored. In this mechanism, glucose enters the cells and subsequently the metabolic cycle. During this process, the ATP/ADP ratio increases, leading to ATP-sensitive potassium (KATP) channel closure, which initiates depolarization that is also dependent on the activity of TRP nonselective ion channels. Depolarization leads to the opening of voltage-gated Na(+) channels (Nav) and subsequently voltage-dependent Ca(2+) channels (Cav). The increase in intracellular Ca(2+) triggers the exocytosis of insulin-containing vesicles. Thus, electrical activity of pancreatic beta cells plays a central role in GSIS. Moreover, many growth factors, incretins, neurotransmitters, and hormones can modulate GSIS, and the channels that participate in GSIS are highly regulated. In this review, we focus on the principal ionic channels (KATP, Nav, and Cav channels) involved in GSIS and how classic and new proteins, hormones, and drugs regulate it. Moreover, we also discuss advances on how metabolic disorders such as metabolic syndrome and diabetes mellitus change channel activity leading to changes in insulin secretion. PMID:27436126

  7. Ubiquitin D Regulates IRE1α/c-Jun N-terminal Kinase (JNK) Protein-dependent Apoptosis in Pancreatic Beta Cells.

    PubMed

    Brozzi, Flora; Gerlo, Sarah; Grieco, Fabio Arturo; Juusola, Matilda; Balhuizen, Alexander; Lievens, Sam; Gysemans, Conny; Bugliani, Marco; Mathieu, Chantal; Marchetti, Piero; Tavernier, Jan; Eizirik, Décio L

    2016-06-01

    Pro-inflammatory cytokines contribute to pancreatic beta cell apoptosis in type 1 diabetes at least in part by inducing endoplasmic reticulum (ER) stress and the consequent unfolded protein response (UPR). It remains to be determined what causes the transition from "physiological" to "apoptotic" UPR, but accumulating evidence indicates that signaling by the ER transmembrane protein IRE1α is critical for this transition. IRE1α activation is regulated by both intra-ER and cytosolic cues. We evaluated the role for the presently discovered cytokine-induced and IRE1α-interacting protein ubiquitin D (UBD) on the regulation of IRE1α and its downstream targets. UBD was identified by use of a MAPPIT (mammalian protein-protein interaction trap)-based IRE1α interactome screen followed by comparison against functional genomic analysis of human and rodent beta cells exposed to pro-inflammatory cytokines. Knockdown of UBD in human and rodent beta cells and detailed signal transduction studies indicated that UBD modulates cytokine-induced UPR/IRE1α activation and apoptosis. UBD expression is induced by the pro-inflammatory cytokines interleukin (IL)-1β and interferon (IFN)-γ in rat and human pancreatic beta cells, and it is also up-regulated in beta cells of inflamed islets from non-obese diabetic mice. UBD interacts with IRE1α in human and rodent beta cells, modulating IRE1α-dependent activation of JNK and cytokine-induced apoptosis. Our data suggest that UBD provides a negative feedback on cytokine-induced activation of the IRE1α/JNK pro-apoptotic pathway in cytokine-exposed beta cells. PMID:27044747

  8. Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells

    PubMed Central

    Hardy, Alexandre B.; Prentice, Kacey J.; Froese, Sean; Liu, Ying; Andrews, Glen K.; Wheeler, Michael B.

    2015-01-01

    Zinc has an important role in normal pancreatic beta cell physiology as it regulates gene transcription, insulin crystallization and secretion, and cell survival. Nevertheless, little is known about how zinc is transported through the plasma membrane of beta cells and which of the class of zinc influx transporters (Zip) is involved. Zip4 was previously shown to be expressed in human and mouse beta cells; however, its function there is still unknown. Therefore, the aim of this study was to define the zinc transport role of Zip4 in beta cells. To investigate this, Zip4 was over-expressed in MIN6 beta cells using a pCMV6-Zip4GFP plasmid. Organelle staining combined with confocal microscopy showed that Zip4 exhibits a widespread localization in MIN6 cells. Time-lapse zinc imaging experiments showed that Zip4 increases cytoplasmic zinc levels. This resulted in increased granular zinc content and glucose-stimulated insulin secretion. Interestingly, it is unlikely that the increased glucose stimulated insulin secretion was triggered by a modulation of mitochondrial function, as mitochondrial membrane potential remained unchanged. To define the role of Zip4 in-vivo, we generated a beta cell-specific knockout mouse model (Zip4BKO). Deletion of the Zip4 gene was confirmed in Zip4BKO islets by PCR, RT-PCR, and immuno-histochemistry. Zip4BKO mice showed slightly improved glucose homeostasis but no change in insulin secretion during an oral glucose tolerance test. While Zip4 was not found to be essential for proper glucose homeostasis and insulin secretion in vivo in mice, this study also found that Zip4 mediates increases in cytoplasmic and granular zinc pools and stimulates glucose dependant insulin secretion in-vitro. PMID:25806541

  9. Age-related differences in the pancreatic beta-cell response to hyperglycemia after eccentric exercise.

    PubMed

    Krishnan, R K; Hernandez, J M; Williamson, D L; O'Gorman, D J; Evans, W J; Kirwan, J P

    1998-09-01

    Eccentric exercise (ECC) causes muscle damage, insulin resistance, and increased pancreatic beta-cell secretion in young individuals. However, the effects of age on the pancreatic beta-cell response to glucose after ECC are unknown. Hyperglycemic clamps (180 min, 10.0 mM) were performed on eight young (age 22 +/- 1 yr) and eight older (age 66 +/- 2 yr) healthy sedentary males without exercise (CONT) and 48 h after ECC. ECC increased (P < 0.02) muscle soreness ratings and plasma creatine kinase concentrations in both groups. Insulin and C-peptide secretions were similar between young and older subjects during CONT clamps. ECC increased (P < 0.05) first-phase (0-10 min) C-peptide area under the curve in young (4.2 +/- 0.4 vs. 3.7 +/- 0.6 nM . min; ECC vs. CONT, respectively) but not in older subjects (3.2 +/- 0.7 vs. 3.5 +/- 0.7 nM . min; ECC vs. CONT), with significant group differences (P < 0.02). Indeed, ECC repressed (P < 0.05) first-phase peak C-peptide concentrations in older subjects (0. 93 +/- 0.16 vs. 1.12 +/- 0.11 nM; ECC vs. CONT). Moreover, first-phase C-peptide-to-insulin molar ratios suggest age-related differences (P < 0.05) in insulin/C-peptide clearance after ECC. Furthermore, the observed C-peptide response after ECC was related to abdominal adiposity [r = -0.62, P < 0.02, and r = -0.66, P < 0. 006, for first and second (10-180 min) phases, respectively]. In conclusion, older individuals did not exhibit the compensatory increase in beta-cell secretion observed among young individuals after ECC. Thus, with increasing age, the pancreatic beta-cell may be less responsive to the physiological stress associated with ECC. PMID:9725813

  10. Joe Doupe lecture: emerging strategies for the preservation of pancreatic beta-cell function in early type 2 diabetes.

    PubMed

    Retnakaran, Ravi

    2014-01-01

    A fundamental problem in the clinical management of type 2 diabetes is the inability to prevent the ongoing deterioration of pancreatic beta-cell function over time that underlies the chronic progressive nature of this condition. Importantly, beta-cell dysfunction has both reversible and irreversible components. Furthermore, the amelioration of reversible beta-cell dysfunction through the early institution of short-term insulin-based therapy has emerged as a strategy that can yield temporary remission of type 2 diabetes. In this context, we have forwarded a novel therapeutic paradigm consisting of initial induction therapy to improve beta-cell function early in the course of diabetes followed by maintenance therapy aimed at preserving this beneficial beta-cell effect. Ultimately, this approach may yield an optimized therapeutic strategy for the durable preservation of beta-cell function and consequent modification of the natural history of type 2 diabetes. PMID:25618275

  11. Nuclear SREBP-1a causes loss of pancreatic {beta}-cells and impaired insulin secretion

    SciTech Connect

    Iwasaki, Yuko; Iwasaki, Hitoshi; Yatoh, Shigeru; Ishikawa, Mayumi; Kato, Toyonori; Matsuzaka, Takashi; Nakagawa, Yoshimi; Yahagi, Naoya; Kobayashi, Kazuto; Takahashi, Akimitsu; Suzuki, Hiroaki; Yamada, Nobuhiro; Shimano, Hitoshi

    2009-01-16

    Transgenic mice expressing nuclear sterol regulatory element-binding protein-1a under the control of the insulin promoter were generated to determine the role of SREBP-1a in pancreatic {beta}-cells. Only low expressors could be established, which exhibited mild hyperglycemia, impaired glucose tolerance, and reduced plasma insulin levels compared to C57BL/6 controls. The islets isolated from the transgenic mice were fewer and smaller, and had decreased insulin content and unaltered glucagon staining. Both glucose- and potassium-stimulated insulin secretions were decreased. The transgenic islets consistently expressed genes for fatty acids and cholesterol synthesis, resulting in accumulation of triglycerides but not cholesterol. PDX-1, {beta}{epsilon}{tau}{alpha}2, MafA, and IRS-2 were suppressed, partially explaining the loss and dysfunction of {beta}-cell mass. The transgenic mice on a high fat/high sucrose diet still exhibited impaired insulin secretion and continuous {beta}-cell growth defect. Therefore, nuclear SREBP-1a, even at a low level, strongly disrupts {beta}-cell mass and function.

  12. Nitric oxide stimulates insulin gene transcription in pancreatic {beta}-cells

    SciTech Connect

    Campbell, S.C. . E-mail: s.c.campbell@ncl.ac.uk; Richardson, H.; Ferris, W.F.; Butler, C.S.; Macfarlane, W.M.

    2007-02-23

    Recent studies have identified a positive role for nitric oxide (NO) in the regulation of pancreatic {beta}-cell function. The aim of this study was to determine the effects of short-term exposure to NO on {beta}-cell gene expression and the activity of the transcription factor PDX-1. NO stimulated the activity of the insulin gene promoter in Min6 {beta}-cells and endogenous insulin mRNA levels in both Min6 and isolated islets of Langerhans. Addition of wortmannin prior to NO stimulation blocked the observed increases in insulin gene promoter activity. Although NO addition stimulated the phosphorylation of p38, inhibition by SB203580 did not block the effect of NO on the insulin gene promoter. NO addition also stimulated both the nuclear accumulation and the DNA binding activity of PDX-1. This study has shown that over 24 h, NO stimulates insulin gene expression, PI-3-kinase activity and the activity of the critical {beta}-cell transcription factor PDX-1.

  13. Junctophilin 3 expresses in pancreatic beta cells and is required for glucose-stimulated insulin secretion.

    PubMed

    Li, L; Pan, Z-F; Huang, X; Wu, B-W; Li, T; Kang, M-X; Ge, R-S; Hu, X-Y; Zhang, Y-H; Ge, L-J; Zhu, D-Y; Wu, Y-L; Lou, Y-J

    2016-01-01

    It is well accepted that junctophilin (JPHs) isoforms act as a physical bridge linking plasma membrane and endoplasmic reticulum (ER) for channel crosstalk in excitable cells. Our purpose is to investigate whether JPHs are involved in the proper communication between Ca(2+) influx and subsequent Ca(2+) amplification in pancreatic beta cells, thereby participating in regulating insulin secretion. The expression of JPH isoforms was examined in human and mouse pancreatic tissues, and JPH3 expression was found in both the beta cells. In mice, knockdown of Jph3 (si-Jph3) in islets decreased glucose-stimulated insulin secretion (GSIS) accompanied by mitochondrial function impairment. Si-Jph3 lowered the insulin secretory response to Ca(2+) signaling in the presence of glucose, and reduced [Ca(2+)]c transient amplitude triggered by caffeine. Si-Jph3 also attenuated mitofusin 2 expression, thereby disturbing the spatial organization of ER-mitochondria contact in islets. These results suggest that the regulation of GSIS by the KATP channel-independent pathways is partly impaired due to decrease of JPH3 expression in mouse islets. JPH3 also binds to type 2 ryanodine receptors (RyR2) in mouse and human pancreatic tissues, which might contribute to Ca(2+) release amplification in GSIS. This study demonstrates some previously unrecognized findings in pancreatic tissues: (1) JPH3 expresses in mouse and human beta cells; (2) si-Jph3 in mouse primary islets impairs GSIS in vitro; (3) impairment in GSIS in si-Jph3 islets is due to changes in RyR2-[Ca(2+)]c transient amplitude and ER-mitochondria contact. PMID:27336719

  14. ER stress in pancreatic beta cells: the thin red line between adaptation and failure.

    PubMed

    Eizirik, Decio L; Cnop, Miriam

    2010-01-01

    Secretory cells, such as pancreatic beta cells, face the challenge of increasing protein synthesis severalfold during acute or chronic stimulation. This poses a burden on the endoplasmic reticulum (ER), the organelle where proinsulin synthesis and folding takes place. Thus, beta cells use various adaptive mechanisms to adjust the functional capacity of the ER to the prevailing demand. These check-and-balance mechanisms are collectively known as the unfolded protein response (UPR). It remains unclear how UPR signaling is ultimately regulated and what delineates the boundaries between a physiological and a pathological response. New discoveries point to the divergent effects of acute and chronic metabolic fluxes and chemical ER stressors on the formation of complexes among UPR transducers, scaffold proteins, and phosphatases. These and other findings provide a first glimpse on how different signals trigger diverging UPR outcomes. PMID:20179270

  15. Properties of the Ca-activated K+ channel in pancreatic beta-cells.

    PubMed

    Atwater, I; Rosario, L; Rojas, E

    1983-12-01

    The existence of [Ca2+]i-activated K+-channels in the pancreatic beta-cell membrane is based in two observations: quinine inhibits K+-permeability and, increasing intracellular Ca2+ stimulates it. The changes in K+-permeability of the beta-cell have been monitored electrically by combining measurements of the dependence of the membrane potential on external K+ concentration and input resistance. The changes in the passive 42K and 86Rb efflux from the whole islet have been measured directly. Intracellular Ca2+ has been increased by various means, including increasing extracellular Ca2+, addition of the Ca2+-ionophore A23187 or noradrenaline and application of mitochondrial uncouplers and blockers. In addition to quinine, many other substances have been found to inhibit or modulate the [Ca2+]i-activated K+-channel. The most important of these is the natural stimulus for insulin secretion, glucose. Glucose may inhibit K+-permeability by lowering intracellular Ca2+. Glibenclamide, a hypoglycaemic sulphonylurea, is about 25 times more active than quinine in blocking the K+-channel in beta-cells. The methylxanthines, c-AMP, various calmodulin inhibitors and Ba2+ also inhibit K+-permeability. Genetically diabetic mice have been studied and show an alteration in the [Ca2+]i-activated K+-channel. It is concluded that the [Ca2+]i-activated K+-channel plays a major role in the normal function of the pancreatic beta-cell. The study of its properties should prove valuable for the understanding and treatment of diabetes. PMID:6323007

  16. Biophysical properties of gap junctions between freshly dispersed pairs of mouse pancreatic beta cells.

    PubMed Central

    Pérez-Armendariz, M; Roy, C; Spray, D C; Bennett, M V

    1991-01-01

    Coupling between beta cells through gap junctions has been postulated as a principal mechanism of electrical synchronization of glucose-induced activity throughout the islet of Langerhans. We characterized junctional conductance between isolated pairs of mouse pancreatic beta cells by whole-cell recording with two independent patch-clamp circuits. Most pairs were coupled (67%, n = 155), although the mean junctional conductance (gj) (215 +/- 110 pS) was lower than reported in other tissues. Coupling could be recorded for long periods, up to 40 min. Voltage imposed across the junctional or nonjunctional membranes had no effect on gj. Up to several hours of treatment to increase intracellular cAMP levels did not affect gj. Electrically coupled pairs did not show transfer of the dye Lucifer yellow. Octanol (2 mM) reversibly decreased gj. Lower concentrations of octanol (0.5 mM) and heptanol (0.5 mM) than required to uncouple beta cells decreased voltage-dependent K+ and Ca2+ currents in nonjunctional membranes. Although gj recorded in these experiments would be expected to be provided by current flowing through only a few channels of the unitary conductance previously reported for other gap junctions, no unitary junctional currents were observed even during reversible suppression of gj by octanol. This result suggests either that the single channel conductance of gap junction channels between beta cells is smaller than in other tissues (less than 20 pS) or that the small mean conductance is due to transitions between open and closed states that are too rapid or too slow to be resolved. Images FIGURE 1 FIGURE 5 PMID:2015391

  17. Glucocorticoids Inhibit Basal and Hormone-Induced Serotonin Synthesis in Pancreatic Beta Cells

    PubMed Central

    Hasni Ebou, Moina; Singh-Estivalet, Amrit; Launay, Jean-Marie; Callebert, Jacques; Tronche, François; Ferré, Pascal; Gautier, Jean-François; Guillemain, Ghislaine; Bréant, Bernadette

    2016-01-01

    Diabetes is a major complication of chronic Glucocorticoids (GCs) treatment. GCs induce insulin resistance and also inhibit insulin secretion from pancreatic beta cells. Yet, a full understanding of this negative regulation remains to be deciphered. In the present study, we investigated whether GCs could inhibit serotonin synthesis in beta cell since this neurotransmitter has been shown to be involved in the regulation of insulin secretion. To this aim, serotonin synthesis was evaluated in vitro after treatment with GCs of either islets from CD1 mice or MIN6 cells, a beta-cell line. We also explored the effect of GCs on the stimulation of serotonin synthesis by several hormones such as prolactin and GLP 1. We finally studied this regulation in islet in two in vivo models: mice treated with GCs and with liraglutide, a GLP1 analog, and mice deleted for the glucocorticoid receptor in the pancreas. We showed in isolated islets and MIN6 cells that GCs decreased expression and activity of the two key enzymes of serotonin synthesis, Tryptophan Hydroxylase 1 (Tph1) and 2 (Tph2), leading to reduced serotonin contents. GCs also blocked the induction of serotonin synthesis by prolactin or by a previously unknown serotonin activator, the GLP-1 analog exendin-4. In vivo, activation of the Glucagon-like-Peptide-1 receptor with liraglutide during 4 weeks increased islet serotonin contents and GCs treatment prevented this increase. Finally, islets from mice deleted for the GR in the pancreas displayed an increased expression of Tph1 and Tph2 and a strong increased serotonin content per islet. In conclusion, our results demonstrate an original inhibition of serotonin synthesis by GCs, both in basal condition and after stimulation by prolactin or activators of the GLP-1 receptor. This regulation may contribute to the deleterious effects of GCs on beta cells. PMID:26901633

  18. Activation of transmembrane bile acid receptor TGR5 stimulates insulin secretion in pancreatic {beta} cells

    SciTech Connect

    Kumar, Divya P.; Rajagopal, Senthilkumar; Mahavadi, Sunila; Mirshahi, Faridoddin; Grider, John R.; Murthy, Karnam S.; Sanyal, Arun J.

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer G protein coupled receptor TGR5 is expressed in mouse and human islets. Black-Right-Pointing-Pointer TGR5 is coupled to activation of Gs and Ca{sup 2+} release via cAMP/Epac/PLC-{epsilon} pathway. Black-Right-Pointing-Pointer Activation of TGR5 by bile salts and selective ligands causes insulin secretion. Black-Right-Pointing-Pointer TGR5 could be a potential therapeutic target to treat diabetes. -- Abstract: Bile acids act as signaling molecules and stimulate the G protein coupled receptor, TGR5, in addition to nuclear farnesoid X receptor to regulate lipid, glucose and energy metabolism. Bile acid induced activation of TGR5 in the enteroendocrine cells promotes glucagon like peptide-1 (GLP-1) release, which has insulinotropic effect in the pancreatic {beta} cells. In the present study, we have identified the expression of TGR5 in pancreatic {beta} cell line MIN6 and also in mouse and human pancreatic islets. TGR5 selective ligands, oleanolic acid (OA) and INT-777 selectively activated G{alpha}{sub s} and caused an increase in intracellular cAMP and Ca{sup 2+}. OA and INT-777 also increased phosphoinositide (PI) hydrolysis and the increase was blocked by NF449 (a selective G{alpha}{sub s} inhibitor) or (U73122) (PI hydrolysis inhibitor). OA, INT-777 and lithocholic acid increased insulin release in MIN6 and human islets and the increase was inhibited by treatment with NF449, (U73122) or BAPTA-AM (chelator of calcium), but not with myristoylated PKI (PKA inhibitor), suggesting that the release is dependent on G{sub s}/cAMP/Ca{sup 2+} pathway. 8-pCPT-2 Prime -O-Me-cAMP, a cAMP analog, which activates Epac, but not PKA also stimulated PI hydrolysis. In conclusion, our study demonstrates that the TGR5 expressed in the pancreatic {beta} cells regulates insulin secretion and highlights the importance of ongoing therapeutic strategies targeting TGR5 in the control of glucose homeostasis.

  19. Effects of antidiabetic agents on pancreatic beta-cell function in gestational diabetes: is there enough evidence?

    PubMed

    Tura, Andrea; Göbl, Christian; Pacini, Giovanni

    2016-01-01

    Gestational diabetes mellitus (GDM) is typically characterized by the presence of insulin resistance. However, recent studies showed that both insulin resistance and pancreatic beta-cell function impairment may contribute to the development of type 2 diabetes in women with history of GDM. In fact, beta-cell function decline was found as significant predictor of later disease in former GDM women progressing towards type 2 diabetes. Despite the evidence of the relevance of beta-cell function quantification in GDM, a low number of studies focused on the effects of GDM treatments on beta-cell function. We briefly present the evidence of the effects on beta-cell function of pharmacological agents, as well as nutrition supplements or medical nutrition therapy, used in the management of GDM. We found that few studies reported information on beta-cell function effects in GDM, despite some agents, such as glyburide, are well known insulin secretagogues. Therefore, further studies should be carried out to clearly assess the effects on beta-cell function of the treatments in GDM women. PMID:26609764

  20. Down-regulation of zinc transporter 8 (SLC30A8) in pancreatic beta-cells promotes cell survival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The pancreatic islet contains high levels of zinc in granular vesicles of beta-cells where insulin is matured, crystallized, and stored before secretion. Zinc is an essential co-factor for insulin crystallization forming dense core in secretory granules. In insulin-containing secretory granules, zin...

  1. Evidence for a slowly exchangeable pool of calcium in the pancreatic beta cell plasma membrane.

    PubMed Central

    Gylfe, E; Hellman, B

    1982-01-01

    1. Exposure to media deprived of Ca2+ resulted in prompt and transient stimulation of 45Ca efflux from beta cell-rich pancreatic islets microdissected from ob/ob-mice and to some extent also from the isolated neurohypophysis. 2. Particular high efflux rates were reached when the Ca2+-deficient medium contained EGTA, but there was no effect of the chelator on the total amount of radioactivity mobilized from the islets. 3. The removal of extracellular Ca2+ was less effective in promoting the 45Ca efflux in the absence of Na+ and no stimulatory response was seen in the presence of 1 mM-La3+. 4. The 45Ca washout was stimulated whether or not the media used for the loading or subsequent perifusion of the islets were supplemented with 20 mM-D-glucose. However, there was no response to a second exposure to a Ca2+-deficient medium even subsequent to redistribution of intracellular calcium induced by temporary lowering of the temperature. 5. It is suggested that the islet 45Ca released by the removal of extracellular Ca2+ originates from a distinct plasma membrane pool which is exchanged slowly compared to most of the calcium at the beta cell periphery. PMID:6752376

  2. Iron Regulation of Pancreatic Beta-Cell Functions and Oxidative Stress.

    PubMed

    Backe, Marie Balslev; Moen, Ingrid Wahl; Ellervik, Christina; Hansen, Jakob Bondo; Mandrup-Poulsen, Thomas

    2016-07-17

    Dietary advice is the cornerstone in first-line treatment of metabolic diseases. Nutritional interventions directed at these clinical conditions mainly aim to (a) improve insulin resistance by reducing energy-dense macronutrient intake to obtain weight loss and (b) reduce fluctuations in insulin secretion through avoidance of rapidly absorbable carbohydrates. However, even in the majority of motivated patients selected for clinical trials, massive efforts using this approach have failed to achieve lasting efficacy. Less attention has been given to the role of micronutrients in metabolic diseases. Here, we review the evidence that highlights (a) the importance of iron in pancreatic beta-cell function and dysfunction in diabetes and (b) the integrative pathophysiological effects of tissue iron levels in the interactions among the beta cell, gut microbiome, hypothalamus, innate and adaptive immune systems, and insulin-sensitive tissues. We propose that clinical trials are warranted to clarify the impact of dietary or pharmacological iron reduction on the development of metabolic disorders. PMID:27146016

  3. Transient receptor potential M3 channels are ionotropic steroid receptors in pancreatic beta cells.

    PubMed

    Wagner, Thomas F J; Loch, Sabine; Lambert, Sachar; Straub, Isabelle; Mannebach, Stefanie; Mathar, Ilka; Düfer, Martina; Lis, Annette; Flockerzi, Veit; Philipp, Stephan E; Oberwinkler, Johannes

    2008-12-01

    Transient receptor potential (TRP) cation channels are renowned for their ability to sense diverse chemical stimuli. Still, for many members of this large and heterogeneous protein family it is unclear how their activity is regulated and whether they are influenced by endogenous substances. On the other hand, steroidal compounds are increasingly recognized to have rapid effects on membrane surface receptors that often have not been identified at the molecular level. We show here that TRPM3, a divalent-permeable cation channel, is rapidly and reversibly activated by extracellular pregnenolone sulphate, a neuroactive steroid. We show that pregnenolone sulphate activates endogenous TRPM3 channels in insulin-producing beta cells. Application of pregnenolone sulphate led to a rapid calcium influx and enhanced insulin secretion from pancreatic islets. Our results establish that TRPM3 is an essential component of an ionotropic steroid receptor enabling unanticipated crosstalk between steroidal and insulin-signalling endocrine systems. PMID:18978782

  4. Impairment of Rat Fetal Beta-Cell Development by Maternal Exposure to Dexamethasone during Different Time-Windows

    PubMed Central

    Dumortier, Olivier; Theys, Nicolas; Ahn, Marie-Thérèse; Remacle, Claude; Reusens, Brigitte

    2011-01-01

    Aim Glucocorticoids (GCs) take part in the direct control of cell lineage during the late phase of pancreas development when endocrine and exocrine cell differentiation occurs. However, other tissues such as the vasculature exert a critical role before that phase. This study aims to investigate the consequences of overexposure to exogenous glucocorticoids during different time-windows of gestation for the development of the fetal endocrine pancreas. Methods Pregnant Wistar rats received dexamethasone acetate in their drinking water (1 µg/ml) during the last week or throughout gestation. Fetuses and their pancreases were analyzed at day 15 and 21 of gestation. Morphometrical analysis was performed on pancreatic sections after immunohistochemistry techniques and insulin secretion was evaluated on fetal islets collected in vitro. Results Dexamethasone given the last week or throughout gestation reduced the beta-cell mass in 21-day-old fetuses by respectively 18% or 62%. This was accompanied by a defect in insulin secretion. The alpha-cell mass was reduced similarly. Neither islet vascularization nor beta-cell proliferation was affected when dexamethasone was administered during the last week, which was however the case when given throughout gestation. When given from the beginning of gestation, dexamethasone reduced the number of cells expressing the early marker of endocrine lineage neurogenin-3 when analyzed at 15 days of fetal age. Conclusions GCs reduce the beta- and alpha-cell mass by different mechanisms according to the stage of development during which the treatment was applied. In fetuses exposed to glucocorticoids the last week of gestation only, beta-cell mass is reduced due to impairment of beta-cell commitment, whereas in fetuses exposed throughout gestation, islet vascularization and lower beta-cell proliferation are involved as well, amplifying the reduction of the endocrine mass. PMID:21991320

  5. Mitochondrial network regulation and its potential interference with inflammatory signals in pancreatic beta cells.

    PubMed

    Baltrusch, Simone

    2016-04-01

    Mitochondria fulfil multiple tasks in nutrient metabolism, energy production, redox homeostasis and stress response, and are essential for pancreatic beta cell function. The dynamism and health of the mitochondrial network is regulated by fission- and fusion-triggering factors and by a quality control system that removes dysfunctional organelles. Alongside the role of mitochondria in regulating apoptotic cell death mediated primarily via production of reactive oxygen species and release of cytochrome c, there is evidence of other links between mitochondria and inflammation that have implications for cell viability. This review briefly outlines two pathways that are potentially vital for pancreatic beta cell function. The first concerns the regulation of Parkin, a protein that acts, not only as a central player in regulating mitophagy, but also as an activator of the NF-ĸB pathway. The fact that expression of optic atrophy protein 1 (OPA1), a mitochondrial fusion inducer and master mitochondrial cristae biogenetic factor, is increased following NF-ĸB activation highlights a point of mitochondrial control that might be influenced by TNFα signalling. A second axis of interest is suggested by IL-6-mediated upregulation of the fission inducer FIS1 alongside downregulation of mitofusin 2 (MFN2), a guard of mitochondrial fusion and metabolism and an inhibitor of apoptosis. This review summarises a presentation given at the 'Islet inflammation in type 2 diabetes' symposium at the 2015 annual meeting of the EASD. It is accompanied two other reviews on topics from this symposium (by Marc Donath, DOI: 10.1007/s00125-016-3873-z , and Jerry Nadler and colleagues, DOI: 10.1007/s00125-016-3890-y ) and a commentary by the Session Chair, Piero Marchetti (DOI: 10.1007/s00125-016-3875-x ). PMID:26873508

  6. Serpine1 Mediates Porphyromonas gingivalis Induced Insulin Secretion in the Pancreatic Beta Cell Line MIN6

    PubMed Central

    Bhat, Uppoor G.; Watanabe, Keiko

    2015-01-01

    Periodontitis is an inflammatory disease resulting in destruction of gingiva and alveolar bone caused by an exuberant host immunological response to periodontal pathogens. Results from a number of epidemiological studies indicate a close association between diabetes and periodontitis. Results from cross-sectional studies indicate that subjects with periodontitis have a higher odds ratio of developing insulin resistance (IR). However, the mechanisms by which periodontitis influences the development of diabetes are not known. Results from our previous studies using an animal model of periodontitis suggest that periodontitis accelerates the onset of hyperinsulinemia and IR. In addition, LPS from a periodontal pathogen, Porphyromonas gingivalis (Pg), stimulates Serpine1 expression in the pancreatic beta cell line MIN6. Based on these observations, we hypothesized that a periodontal pathogen induces hyperinsulinemia and Serpine1 may be involved in this process. To test this hypothesis, we co-incubated Pg with the pancreatic beta cell line MIN6 and measured the effect on insulin secretion by MIN6 cells. We further determined the involvement of Serpine1 in insulin secretion by downregulating Serpine1 expression. Our results indicated that Pg stimulated insulin secretion by approximately 3.0 fold under normoglycemic conditions. In a hyperglycemic state, Pg increased insulin secretion by 1.5 fold. Pg significantly upregulated expression of the Serpine1 gene and this was associated with increased secretion of insulin by MIN6 cells. However, cells with downregulated Serpine1 expression were resistant to Pg stimulated insulin secretion under normoglycemic conditions. We conclude that the periodontal pathogen, Pg, induced insulin secretion by MIN6 cells and this induction was, in part, Serpine1 dependent. Thus, Serpine1 may play a pivotal role in insulin secretion during the accelerated development of hyperinsulinemia and the resulting IR in the setting of periodontitis. PMID

  7. Mafa expression enhances glucose-responsive insulin secretion in neonatal rat beta cells

    PubMed Central

    Aguayo-Mazzucato, C.; Koh, A.; El Khattabi, I.; Li, W.-C.; Toschi, E.; Jermendy, A.; Juhl, K.; Mao, K.; Weir, G. C.

    2011-01-01

    Aim/hypothesis Neonatal beta cells lack glucose-stimulated insulin secretion and are thus functionally immature. We hypothesised that this lack of glucose responsiveness results from a generalised low expression of genes characteristic of mature functional beta cells. Important glucose-responsive transcription factors, Mafa and Pdx1, regulate genes involved in insulin synthesis and secretion, and have been implicated in late beta cell development. The aim of this study was to assess whether Mafa and/or Pdx1 regulates the postnatal functional maturation of beta cells. Methods By quantitative PCR we evaluated expression of these and other beta cell genes over the first month compared with adult. After infection with adenovirus expressing MAFA, Pdx1 or green fluorescent protein (Gfp), P2 rat islets were evaluated by RT-PCR and insulin secretion with static incubation and reverse haemolytic plaque assay (RHPA). Results At P2 most beta cell genes were expressed at about 10% of adult, but by P7 Pdx1 and Neurod1 no longer differ from adult; by contrast, Mafa expression remained significantly lower than adult through P21. Overexpression of Pdx1 increased Mafa, Neurod1, glucokinase (Gck) mRNA and insulin content but failed to enhance glucose responsiveness. Similar overexpression of MAFA resulted in increased Neurod1, Nkx6-1, Gck and Glp1r mRNAs and no change in insulin content but, importantly, acquisition of glucose-responsive insulin secretion. Both the percentage of secreting beta cells and the amount of insulin secreted per beta cell increased, approaching that of adult beta cells. Conclusions/interpretation In the process of functional maturation acquiring glucose-responsive insulin secretion, neonatal beta cells undergo a coordinated gene expression programme in which Mafa plays a crucial role. PMID:21190012

  8. Hepatocyte nuclear factor 3beta is involved in pancreatic beta-cell-specific transcription of the pdx-1 gene.

    PubMed Central

    Wu, K L; Gannon, M; Peshavaria, M; Offield, M F; Henderson, E; Ray, M; Marks, A; Gamer, L W; Wright, C V; Stein, R

    1997-01-01

    The mammalian homeobox gene pdx-1 is expressed in pluripotent precursor cells in the dorsal and ventral pancreatic bud and duodenal endoderm, which will produce the pancreas and the rostral duodenum. In the adult, pdr-1 is expressed principally within insulin-secreting pancreatic islet beta cells and cells of the duodenal epithelium. Our objective in this study was to localize sequences within the mouse pdx-1 gene mediating selective expression within the islet. Studies of transgenic mice in which a genomic fragment of the mouse pdx-1 gene from kb -4.5 to +8.2 was used to drive a beta-galactosidase reporter showed that the control sequences sufficient for appropriate developmental and adult specific expression were contained within this region. Three nuclease-hypersensitive sites, located between bp -2560 and -1880 (site 1), bp -1330 and -800 (site 2), and bp -260 and +180 (site 3), were identified within the 5'-flanking region of the endogenous pdx-1 gene. Pancreatic beta-cell-specific expression was shown to be controlled by sequences within site 1 from an analysis of the expression pattern of various pdr-1-herpes simplex virus thymidine kinase promoter expression constructs in transfected beta-cell and non-beta-cell lines. Furthermore, we also established that this region was important in vivo by demonstrating that expression from a site 1-driven beta-galactosidase reporter construct was directed to islet beta-cells in transgenic mice. The activity of the site 1-driven constructs was reduced substantially in beta-cell lines by mutating a hepatocyte nuclear factor 3 (HNF3)-like site located between nucleotides -2007 and -1996. Gel shift analysis indicated that HNF3beta present in islet beta cells binds to this element. Immunohistochemical studies revealed that HNF3beta was present within the nuclei of almost all islet beta cells and subsets of pancreatic acinar cells. Together, these results suggest that HNF3beta, a key regulator of endodermal cell lineage

  9. Nkx6.1 controls a gene regulatory network required for establishing and maintaining pancreatic Beta cell identity.

    PubMed

    Schaffer, Ashleigh E; Taylor, Brandon L; Benthuysen, Jacqueline R; Liu, Jingxuan; Thorel, Fabrizio; Yuan, Weiping; Jiao, Yang; Kaestner, Klaus H; Herrera, Pedro L; Magnuson, Mark A; May, Catherine Lee; Sander, Maike

    2013-01-01

    All pancreatic endocrine cell types arise from a common endocrine precursor cell population, yet the molecular mechanisms that establish and maintain the unique gene expression programs of each endocrine cell lineage have remained largely elusive. Such knowledge would improve our ability to correctly program or reprogram cells to adopt specific endocrine fates. Here, we show that the transcription factor Nkx6.1 is both necessary and sufficient to specify insulin-producing beta cells. Heritable expression of Nkx6.1 in endocrine precursors of mice is sufficient to respecify non-beta endocrine precursors towards the beta cell lineage, while endocrine precursor- or beta cell-specific inactivation of Nkx6.1 converts beta cells to alternative endocrine lineages. Remaining insulin(+) cells in conditional Nkx6.1 mutants fail to express the beta cell transcription factors Pdx1 and MafA and ectopically express genes found in non-beta endocrine cells. By showing that Nkx6.1 binds to and represses the alpha cell determinant Arx, we identify Arx as a direct target of Nkx6.1. Moreover, we demonstrate that Nkx6.1 and the Arx activator Isl1 regulate Arx transcription antagonistically, thus establishing competition between Isl1 and Nkx6.1 as a critical mechanism for determining alpha versus beta cell identity. Our findings establish Nkx6.1 as a beta cell programming factor and demonstrate that repression of alternative lineage programs is a fundamental principle by which beta cells are specified and maintained. Given the lack of Nkx6.1 expression and aberrant activation of non-beta endocrine hormones in human embryonic stem cell (hESC)-derived insulin(+) cells, our study has significant implications for developing cell replacement therapies. PMID:23382704

  10. Beta-cell metabolic alterations under chronic nutrient overload in rat and human islets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this study was to assess multifactorial Beta-cell responses to metabolic perturbations in primary rat and human islets. Treatment of dispersed rat islet cells with elevated glucose and free fatty acids (FFAs, oleate:palmitate = 1:1 v/v) resulted in increases in the size and the number of ...

  11. Bulk-like endocytosis plays an important role in the recycling of insulin granules in pancreatic beta cells.

    PubMed

    Wen, Du; Xue, Yanhong; Liang, Kuo; Yuan, Tianyi; Lu, Jingze; Zhao, Wei; Xu, Tao; Chen, Liangyi

    2012-08-01

    Although bulk endocytosis has been found in a number of neuronal and endocrine cells, the molecular mechanism and physiological function of bulk endocytosis remain elusive. In pancreatic beta cells, we have observed bulk-like endocytosis evoked both by flash photolysis and trains of depolarization. Bulk-like endocytosis is a clathrin-independent process that is facilitated by enhanced extracellular Ca(2+) entry and suppressed by the inhibition of dynamin function. Moreover, defects in bulk-like endocytosis are accompanied by hyperinsulinemia in primary beta cells dissociated from diabetic KKAy mice, which suggests that bulk-like endocytosis plays an important role in maintaining the exo-endocytosis balance and beta cell secretory capability. PMID:22729398

  12. Induction of beta-cell resistance to hypoxia and technologies for oxygen delivery to transplanted pancreatic islets.

    PubMed

    Lazard, Daniel; Vardi, Pnina; Bloch, Konstantin

    2012-09-01

    Hypoxia is believed to be a crucial factor involved in cell adaptation to environmental stress. Islet transplantation, especially with immunoisolated islets, interrupts vascular connections, resulting in the substantially decreased delivery of oxygen and nutrients to islet cells. Insulin-producing pancreatic beta cells are known to be highly susceptible to oxygen deficiency. Such susceptibility to hypoxia is believed to be one of the main causes of beta-cell death in the post-transplantation period. Different strategies have been developed for the protection of beta cells against hypoxic injury and for oxygen delivery to transplanted islets. The enhancement of beta-cell defense properties against hypoxia has been achieved using various techniques such as gene transfection, drug supplementation, co-culturing with stem cells and cell selection. Technologies for oxygen delivery to transplanted islets include local neovascularization of subcutaneous sites, electrochemical and photosynthetic oxygen generation, oxygen refuelling of bio-artificial pancreas and whole body oxygenation by using hyperbaric therapy. Progress in the field of oxygen technologies for islet transplantation requires a multidisciplinary approach to explore and optimize the interaction between components of the biological system and different technological processes. This review article focuses mainly on the recently developed strategies for oxygenation and protection from hypoxic injury - to achieve stable and long-term normoglycaemia in diabetic patients with transplanted pancreatic islets. PMID:22389124

  13. Measuring phospholipase D activity in insulin-secreting pancreatic beta-cells and insulin-responsive muscle cells and adipocytes.

    PubMed

    Cazzolli, Rosanna; Huang, Ping; Teng, Shuzhi; Hughes, William E

    2009-01-01

    Phospholipase D (PLD) is an enzyme producing phosphatidic acid and choline through hydrolysis of phosphatidylcholine. The enzyme has been identified as a member of a variety of signal transduction cascades and as a key regulator of numerous intracellular vesicle trafficking processes. A role for PLD in regulating glucose homeostasis is emerging as the enzyme has recently been identified in events regulating exocytosis of insulin from pancreatic beta-cells and also in insulin-stimulated glucose uptake through controlling GLUT4 vesicle exocytosis in muscle and adipose tissue. We present methodologies for assessing cellular PLD activity in secretagogue-stimulated insulin-secreting pancreatic beta-cells and also insulin-stimulated adipocyte and muscle cells, two of the principal insulin-responsive cell types controlling blood glucose levels. PMID:19160674

  14. The Sherman-Rinzel-Keizer model for bursting electrical activity in the pancreatic. beta. -cell

    SciTech Connect

    Pernarowski, M.; Kevorkian, J. . Dept. of Applied Mathematics); Miura, R.M. )

    1990-03-01

    Pancreatic {beta}-cells exhibit periodic bursting electrical activity (BEA) consisting of active and silent phases. The Sherman-Rinzel-Keizer (SRK) model of this phenomenon consists of three coupled first-order nonlinear differential equations which describe the dynamics of the membrane potential, the activation parameter for the voltage-gated potassium channel, and the intracellular calcium concentration. These equations are nondimensionalized and transformed into a Lienard differential equation coupled to a single first-order differential equation for the slowly changing nondimensional calcium concentration. Leading-order perturbation problems are derived for the silent and active phases of the BEA on slow and fast time scales. Numerical solutions of these leading-order problems are compared with those for the exact equation in their respective regions. The leading-order solution in the active phase has a limit cycle behavior with a slowly varying frequency. It is observed that the damping term'' in the Lienard equation is small numerically. 26 refs., 6 figs., 2 tabs.

  15. Nkx6.1 is essential for maintaining the functional state of pancreatic beta cells.

    PubMed

    Taylor, Brandon L; Liu, Fen-Fen; Sander, Maike

    2013-09-26

    Recently, loss of beta-cell-specific traits has been proposed as an early cause of beta cell failure in diabetes. However, the molecular mechanisms that underlie the loss of beta cell features remain unclear. Here, we identify an Nkx6.1-controlled gene regulatory network as essential for maintaining the functional and molecular traits of mature beta cells. Conditional Nkx6.1 inactivation in adult mice caused rapid-onset diabetes and hypoinsulinemia. Genome-wide analysis of Nkx6.1-regulated genes and functional assays further revealed a critical role for Nkx6.1 in the control of insulin biosynthesis, insulin secretion, and beta cell proliferation. Over time, Nkx6.1-deficient beta cells acquired molecular characteristics of delta cells, revealing a molecular link between impaired beta cell functional properties and loss of cell identity. Given that Nkx6.1 levels are reduced in human type 2 diabetic beta cells, our study lends support to the concept that loss of beta cell features could contribute to the pathogenesis of diabetes. PMID:24035389

  16. Drp1 guarding of the mitochondrial network is important for glucose-stimulated insulin secretion in pancreatic beta cells.

    PubMed

    Reinhardt, Florian; Schultz, Julia; Waterstradt, Rica; Baltrusch, Simone

    2016-06-10

    Mitochondria form a tubular network in mammalian cells, and the mitochondrial life cycle is determined by fission, fusion and autophagy. Dynamin-related protein 1 (Drp1) has a pivotal role in these processes because it alone is able to constrict mitochondria. However, the regulation and function of Drp1 have been shown to vary between cell types. Mitochondrial morphology affects mitochondrial metabolism and function. In pancreatic beta cells mitochondrial metabolism is a key component of the glucose-induced cascade of insulin secretion. The goal of the present study was to investigate the action of Drp1 in pancreatic beta cells. For this purpose Drp1 was down-regulated by means of shDrp1 in insulin-secreting INS1 cells and mouse pancreatic islets. In INS1 cells reduced Drp1 expression resulted in diminished expression of proteins regulating mitochondrial fusion, namely mitofusin 1 and 2, and optic atrophy protein 1. Diminished mitochondrial dynamics can therefore be assumed. After down-regulation of Drp1 in INS1 cells and spread mouse islets the initially homogenous mitochondrial network characterised by a moderate level of interconnections shifted towards high heterogeneity with elongated, clustered and looped mitochondria. These morphological changes were found to correlate directly with functional alterations. Mitochondrial membrane potential and ATP generation were significantly reduced in INS1 cells after Drp1down-regulation. Finally, a significant loss of glucose-stimulated insulin secretion was demonstrated in INS1 cells and mouse pancreatic islets. In conclusion, Drp1 expression is important in pancreatic beta cells to maintain the regulation of insulin secretion. PMID:27154223

  17. Inorganic mercury causes pancreatic beta-cell death via the oxidative stress-induced apoptotic and necrotic pathways

    SciTech Connect

    Chen Yawen; Huang Chunfa; Yang Chingyao; Yen Chengchieh; Tsai Kehsung; Liu Shinghwa

    2010-03-15

    Mercury is a well-known highly toxic metal. In this study, we characterize and investigate the cytotoxicity and its possible mechanisms of inorganic mercury in pancreatic beta-cells. Mercury chloride (HgCl{sub 2}) dose-dependently decreased the function of insulin secretion and cell viability in pancreatic beta-cell-derived HIT-T15 cells and isolated mouse pancreatic islets. HgCl{sub 2} significantly increased ROS formation in HIT-T15 cells. Antioxidant N-acetylcysteine effectively reversed HgCl{sub 2}-induced insulin secretion dysfunction in HIT-T15 cells and isolated mouse pancreatic islets. Moreover, HgCl{sub 2} increased sub-G1 hypodiploids and annexin-V binding in HIT-T15 cells, indicating that HgCl{sub 2} possessed ability in apoptosis induction. HgCl{sub 2} also displayed several features of mitochondria-dependent apoptotic signals including disruption of the mitochondrial membrane potential, increase of mitochondrial cytochrome c release and activations of poly (ADP-ribose) polymerase (PARP) and caspase 3. Exposure of HIT-T15 cells to HgCl{sub 2} could significantly increase both apoptotic and necrotic cell populations by acridine orange/ethidium bromide dual staining. Meanwhile, HgCl{sub 2} could also trigger the depletion of intracellular ATP levels and increase the LDH release from HIT-T15 cells. These HgCl{sub 2}-induced cell death-related signals could be significantly reversed by N-acetylcysteine. The intracellular mercury levels were markedly elevated in HgCl{sub 2}-treated HIT-T15 cells. Taken together, these results suggest that HgCl{sub 2}-induced oxidative stress causes pancreatic beta-cell dysfunction and cytotoxicity involved the co-existence of apoptotic and necrotic cell death.

  18. GLIS3, a susceptibility gene for type 1 and type 2 diabetes, modulates pancreatic beta cell apoptosis via regulation of a splice variant of the BH3-only protein Bim.

    PubMed

    Nogueira, Tatiane C; Paula, Flavia M; Villate, Olatz; Colli, Maikel L; Moura, Rodrigo F; Cunha, Daniel A; Marselli, Lorella; Marchetti, Piero; Cnop, Miriam; Julier, Cécile; Eizirik, Decio L

    2013-05-01

    Mutations in human Gli-similar (GLIS) 3 protein cause neonatal diabetes. The GLIS3 gene region has also been identified as a susceptibility risk locus for both type 1 and type 2 diabetes. GLIS3 plays a role in the generation of pancreatic beta cells and in insulin gene expression, but there is no information on the role of this gene on beta cell viability and/or susceptibility to immune- and metabolic-induced stress. GLIS3 knockdown (KD) in INS-1E cells, primary FACS-purified rat beta cells, and human islet cells decreased expression of MafA, Ins2, and Glut2 and inhibited glucose oxidation and insulin secretion, confirming the role of this transcription factor for the beta cell differentiated phenotype. GLIS3 KD increased beta cell apoptosis basally and sensitized the cells to death induced by pro-inflammatory cytokines (interleukin 1β + interferon-γ) or palmitate, agents that may contribute to beta cell loss in respectively type 1 and 2 diabetes. The increased cell death was due to activation of the intrinsic (mitochondrial) pathway of apoptosis, as indicated by cytochrome c release to the cytosol, Bax translocation to the mitochondria and activation of caspases 9 and 3. Analysis of the pathways implicated in beta cell apoptosis following GLIS3 KD indicated modulation of alternative splicing of the pro-apoptotic BH3-only protein Bim, favouring expression of the pro-death variant BimS via inhibition of the splicing factor SRp55. KD of Bim abrogated the pro-apoptotic effect of GLIS3 loss of function alone or in combination with cytokines or palmitate. The present data suggest that altered expression of the candidate gene GLIS3 may contribute to both type 1 and 2 type diabetes by favouring beta cell apoptosis. This is mediated by alternative splicing of the pro-apoptotic protein Bim and exacerbated formation of the most pro-apoptotic variant BimS. PMID:23737756

  19. GLIS3, a Susceptibility Gene for Type 1 and Type 2 Diabetes, Modulates Pancreatic Beta Cell Apoptosis via Regulation of a Splice Variant of the BH3-Only Protein Bim

    PubMed Central

    Colli, Maikel L.; Moura, Rodrigo F.; Cunha, Daniel A.; Marselli, Lorella; Marchetti, Piero; Cnop, Miriam; Julier, Cécile; Eizirik, Decio L.

    2013-01-01

    Mutations in human Gli-similar (GLIS) 3 protein cause neonatal diabetes. The GLIS3 gene region has also been identified as a susceptibility risk locus for both type 1 and type 2 diabetes. GLIS3 plays a role in the generation of pancreatic beta cells and in insulin gene expression, but there is no information on the role of this gene on beta cell viability and/or susceptibility to immune- and metabolic-induced stress. GLIS3 knockdown (KD) in INS-1E cells, primary FACS-purified rat beta cells, and human islet cells decreased expression of MafA, Ins2, and Glut2 and inhibited glucose oxidation and insulin secretion, confirming the role of this transcription factor for the beta cell differentiated phenotype. GLIS3 KD increased beta cell apoptosis basally and sensitized the cells to death induced by pro-inflammatory cytokines (interleukin 1β + interferon-γ) or palmitate, agents that may contribute to beta cell loss in respectively type 1 and 2 diabetes. The increased cell death was due to activation of the intrinsic (mitochondrial) pathway of apoptosis, as indicated by cytochrome c release to the cytosol, Bax translocation to the mitochondria and activation of caspases 9 and 3. Analysis of the pathways implicated in beta cell apoptosis following GLIS3 KD indicated modulation of alternative splicing of the pro-apoptotic BH3-only protein Bim, favouring expression of the pro-death variant BimS via inhibition of the splicing factor SRp55. KD of Bim abrogated the pro-apoptotic effect of GLIS3 loss of function alone or in combination with cytokines or palmitate. The present data suggest that altered expression of the candidate gene GLIS3 may contribute to both type 1 and 2 type diabetes by favouring beta cell apoptosis. This is mediated by alternative splicing of the pro-apoptotic protein Bim and exacerbated formation of the most pro-apoptotic variant BimS. PMID:23737756

  20. Direct Reprogramming for Pancreatic Beta-Cells Using Key Developmental Genes

    PubMed Central

    Cavelti-Weder, Claudia; Li, Weida; Zumsteg, Adrian; Stemann, Marianne; Yamada, Takatsugu; Bonner-Weir, Susan; Weir, Gordon

    2015-01-01

    Direct reprogramming is a promising approach for regenerative medicine whereby one cell type is directly converted into another without going through a multipotent or pluripotent stage. This reprogramming approach has been extensively explored for the generation of functional insulin-secreting cells from non-beta-cells with the aim of developing novel cell therapies for the treatment of people with diabetes lacking sufficient endogenous beta-cells. A common approach for such conversion studies is the introduction of key regulators that are important in controlling beta-cell development and maintenance. In this review, we will summarize the recent advances in the field of beta-cell reprogramming and discuss the challenges of creating functional and long-lasting beta-cells. PMID:26998407

  1. Glucagon-Like Peptide-1 Triggers Protective Pathways in Pancreatic Beta-Cells Exposed to Glycated Serum

    PubMed Central

    Puddu, Alessandra; Sanguineti, Roberta; Durante, Arianna; Nencioni, Alessio; Mach, François; Montecucco, Fabrizio; Viviani, Giorgio L.

    2013-01-01

    Advanced glycation end products (AGEs) might play a pathophysiological role in the development of diabetes and its complications. AGEs negatively affect pancreatic beta-cell function and the expression of transcriptional factors regulating insulin gene. Glucagon-like peptide-1 (GLP-1), an incretin hormone that regulates glucose homeostasis, might counteract the harmful effects of AGEs on the beta cells in culture. The aim of this study was to identify the intracellular mechanisms underlying GLP-1-mediated protection from AGE-induced detrimental activities in pancreatic beta cells. HIT-T15 cells were cultured for 5 days with glycated serum (GS, consisting in a pool of AGEs), in the presence or absence of 10 nmol/L GLP-1. After evaluation of oxidative stress, we determined the expression and subcellular localization of proteins involved in maintaining redox balance and insulin gene expression, such as nuclear factor erythroid-derived 2 (Nrf2), glutathione reductase, PDX-1, and MafA. Then, we investigated proinsulin production. The results showed that GS increased oxidative stress, reduced protein expression of all investigated factors through proteasome activation, and decreased proinsulin content. Furthermore, GS reduced ability of PDX-1 and MafA to bind DNA. Coincubation with GLP-1 reversed these GS-mediated detrimental effects. In conclusion, GLP-1, protecting cells against oxidants, triggers protective intercellular pathways in HIT-T15 cells exposed to GS. PMID:23737644

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

    PubMed Central

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

    2014-01-01

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

  3. Nicotinamide-functionalized multiwalled carbon nanotubes increase insulin production in pancreatic beta cells via MIF pathway

    PubMed Central

    Ilie, Ioana; Ilie, Razvan; Mocan, Teodora; Tabaran, Flaviu; Iancu, Cornel; Mocan, Lucian

    2013-01-01

    Recent data in the literature support the role of nicotinamide (NA) as a pharmacologic agent that stimulates pancreatic beta-cells to produce insulin in vitro. There are data showing that carbon nanotubes may be useful in initiating and maintaining cellular metabolic responses. This study shows that administration of multiwalled carbon nanotubes (MWCNTs) functionalized with nicotinamide (NA-MWCNTs) leads to significant insulin production compared with individual administration of NA, MWCNTs, and a control solution. Treatment of 1.4E7 cells for 30 minutes with NA-MWCNTs at concentrations ranging from 1 mg/L to 20 mg/L resulted in significantly increased insulin release (0.18 ± 0.026 ng/mL for 1 mg/L, 0.21 ± 0.024 ng/mL for 5 mg/L, and 0.27 ± 0.028 ng/mL for 20 mg/L). Thus, compared with cells treated with NA only (0.1 ± 0.01 ng/mL for 1 mg/L, 0.12 ± 0.017 ng/mL for 5 mg/L, and 0.17 ± 0.01 ng/mL for 20 mg/L) we observed a significant positive effect on insulin release in cells treated with NA-MWCNTs. The results were confirmed using flow cytometry, epifluorescence microscopy combined with immunochemistry staining, and enzyme-linked immunosorbent assay techniques. In addition, using immunofluorescence microscopy techniques, we were able to demonstrate that MWCNTs enhance insulin production via the macrophage migration inhibitory factor pathway. The application and potential of NA combined with MWCNTs as an antidiabetic agent may represent the beginning of a new chapter in the nanomediated treatment of diabetes mellitus. PMID:24039418

  4. Knockdown of prolactin receptors in a pancreatic beta cell line: effects on DNA synthesis, apoptosis, and gene expression.

    PubMed

    Arumugam, Ramamani; Fleenor, Don; Freemark, Michael

    2014-08-01

    Prolactin (PRL) and placental lactogen stimulate beta cell replication and insulin production in vitro and in vivo. The molecular mechanisms by which lactogens promote beta cell expansion are unclear. We treated rat insulinoma cells with a PRL receptor (PRLR) siRNA to determine if PRLR signaling is required for beta cell DNA synthesis and cell survival and to identify beta cell cycle genes whose expression depends upon lactogen action. Effects of PRLR knockdown were compared with those of PRL treatment. PRLR knockdown (-80 %) reduced DNA synthesis, increased apoptosis, and inhibited expression of cyclins D2 and B2, IRS-2, Tph1, and the anti-apoptotic protein PTTG1; p21 and BCL6 mRNAs increased. Conversely, PRL treatment increased DNA synthesis, reduced apoptosis, and enhanced expression of A, B and D2 cyclins, CDK1, IRS-2, FoxM1, BCLxL, and PTTG1; BCL6 declined. PRLR signaling is required for DNA synthesis and survival of rat insulinoma cells. The effects of lactogens are mediated by down-regulation of cell cycle inhibitors (BCL6, p21) and induction of A, B, and D2 cyclins, IRS-2, Tph1, FoxM1, and the anti-apoptotic proteins BCLxL and PTTG1. PMID:24114406

  5. Maternal obesity accelerates fetal pancreatic beta-cell but not alpha-cell development in sheep: prenatal consequences.

    PubMed

    Ford, Stephen P; Zhang, Liren; Zhu, Meijun; Miller, Myrna M; Smith, Derek T; Hess, Bret W; Moss, Gary E; Nathanielsz, Peter W; Nijland, Mark J

    2009-09-01

    Maternal obesity affects offspring weight, body composition, and organ function, increasing diabetes and metabolic syndrome risk. We determined effects of maternal obesity and a high-energy diet on fetal pancreatic development. Sixty days prior to breeding, ewes were assigned to control [100% of National Research Council (NRC) recommendations] or obesogenic (OB; 150% NRC) diets. At 75 days gestation, OB ewes exhibited elevated insulin-to-glucose ratios at rest and during a glucose tolerance test, demonstrating insulin resistance compared with control ewes. In fetal studies, ewes ate their respective diets from 60 days before to 75 days after conception when animals were euthanized under general anesthesia. OB and control ewes increased in body weight by approximately 43% and approximately 6%, respectively, from diet initiation until necropsy. Although all organs were heavier in fetuses from OB ewes, only pancreatic weight increased as a percentage of fetal weight. Blood glucose, insulin, and cortisol were elevated in OB ewes and fetuses on day 75. Insulin-positive cells per unit pancreatic area were 50% greater in fetuses from OB ewes as a result of increased beta-cell mitoses rather than decreased programmed cell death. Lambs of OB ewes were born earlier but weighed the same as control lambs; however, their crown-to-rump length was reduced, and their fat mass was increased. We conclude that increased systemic insulin in fetuses from OB ewes results from increased glucose exposure and/or cortisol-induced accelerated fetal beta-cell maturation and may contribute to premature beta-cell function loss and predisposition to obesity and metabolic disease in offspring. PMID:19605766

  6. The class I histone deacetylase inhibitor MS-275 prevents pancreatic beta cell death induced by palmitate.

    PubMed

    Plaisance, Valérie; Rolland, Laure; Gmyr, Valéry; Annicotte, Jean-Sébastien; Kerr-Conte, Julie; Pattou, François; Abderrahmani, Amar

    2014-01-01

    Elevation of the dietary saturated fatty acid palmitate contributes to the reduction of functional beta cell mass in the pathogenesis of type 2 diabetes. The diabetogenic effect of palmitate is achieved by increasing beta cell death through induction of the endoplasmic reticulum (ER) stress markers including activating transcription factor 3 (Atf3) and CAAT/enhancer-binding protein homologous protein-10 (Chop). In this study, we investigated whether treatment of beta cells with the MS-275, a HDAC1 and HDAC3 activity inhibitor which prevents beta cell death elicited by cytokines, is beneficial for combating beta cell dysfunction caused by palmitate. We show that culture of isolated human islets and MIN6 cells with MS-275 reduced apoptosis evoked by palmitate. The protective effect of MS-275 was associated with the attenuation of the expression of Atf3 and Chop. Silencing of HDAC3, but not of HDAC1, mimicked the effects of MS-275 on the expression of the two ER stress markers and apoptosis. These data point to HDAC3 as a potential drug target for preserving beta cells against lipotoxicity in diabetes. PMID:25610877

  7. The Class I Histone Deacetylase Inhibitor MS-275 Prevents Pancreatic Beta Cell Death Induced by Palmitate

    PubMed Central

    Plaisance, Valérie; Rolland, Laure; Gmyr, Valéry; Annicotte, Jean-Sébastien; Kerr-Conte, Julie; Pattou, François; Abderrahmani, Amar

    2014-01-01

    Elevation of the dietary saturated fatty acid palmitate contributes to the reduction of functional beta cell mass in the pathogenesis of type 2 diabetes. The diabetogenic effect of palmitate is achieved by increasing beta cell death through induction of the endoplasmic reticulum (ER) stress markers including activating transcription factor 3 (Atf3) and CAAT/enhancer-binding protein homologous protein-10 (Chop). In this study, we investigated whether treatment of beta cells with the MS-275, a HDAC1 and HDAC3 activity inhibitor which prevents beta cell death elicited by cytokines, is beneficial for combating beta cell dysfunction caused by palmitate. We show that culture of isolated human islets and MIN6 cells with MS-275 reduced apoptosis evoked by palmitate. The protective effect of MS-275 was associated with the attenuation of the expression of Atf3 and Chop. Silencing of HDAC3, but not of HDAC1, mimicked the effects of MS-275 on the expression of the two ER stress markers and apoptosis. These data point to HDAC3 as a potential drug target for preserving beta cells against lipotoxicity in diabetes. PMID:25610877

  8. Adult Human Pancreatic Islet Beta-Cells Display Limited Turnover and Long Lifespan as Determined by In-Vivo Thymidine Analog Incorporation and Radiocarbon Dating

    SciTech Connect

    Perl, S; Kushner, J A; Buchholz, B A; Meeker, A K; Stein, G M; Hsieh, M; Kirby, M; Pechhold, S; Liu, E H; Harlan, D M; Tisdale, J F

    2010-03-15

    Diabetes mellitus results from an absolute or relative deficiency of insulin producing pancreatic beta-cells. The adult human beta-cell's turnover rate remains unknown. We employed novel techniques to examine adult human islet beta-cell turnover and longevity in vivo. Subjects enrolled in NIH clinical trials received thymidine analogues [iododeoxyuridine (IdU) or bromodeoxyuridine (BrdU)] 8-days to 4-years prior to death. Archival autopsy samples from ten patients (aged 17-74 years) were employed to assess beta-cell turnover by scoring nuclear analog labeling within insulin staining cells. Human adult beta-cell longevity was determined by estimating the cells genomic DNA integration of atmospheric carbon-14 ({sup 14}C). DNA was purified from pancreatic islets isolated from cadaveric donors; whole islet prep DNA was obtained from a 15 year old donor, and purified beta-cell DNA was obtained from two donors (age 48 and 80 years). {sup 14}C levels were then determined using accelerator mass spectrometry (AMS). Cellular 'birth date' was determined by comparing the subject's DNA {sup 14}C content relative to a well-established {sup 14}C atmospheric prevalence curve. In the two subjects less than age 20 years, 1-2% of the beta-cell nuclei co-stained for BrdU/IdU. No beta-cell nuclei co-stained in the eight patients more than 30 years old. Consistent with the BrdU/IdU turnover data, beta-cell DNA {sup 14}C content indicated the cells 'birth date' occurred within the subject's first 30 years of life. Under typical circumstances, adult human beta-cells and their cellular precursors are established by young adulthood.

  9. Beneficial effect of 17{beta}-estradiol on hyperglycemia and islet {beta}-cell functions in a streptozotocin-induced diabetic rat model

    SciTech Connect

    Yamabe, Noriko; Kang, Ki Sung; Zhu Baoting

    2010-11-15

    The modulating effect of estrogen on glucose homeostasis remains a controversial issue at present. In this study, we sought to determine the beneficial effect of 17{beta}-estradiol (E{sub 2}) on hyperglycemia and islet {beta}-cell functions in streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were injected i.p. with STZ to induce a relatively mild diabetic condition. The rats were then treated with E{sub 2} orally at 500 {mu}g/kg body weight/day for 15 days to evaluate the modulating effect on hyperglycemia, insulin secretion, and islet {beta}-cell proliferation. E{sub 2} administration for 10 days significantly lowered plasma glucose levels, increased plasma insulin levels, and improved glucose tolerance by attenuating insulin response to oral glucose loading. These beneficial effects of E{sub 2} were accompanied by increases in islet number and volume, rate of islet cell proliferation, and the amount of insulin secreted. The growth-stimulatory effect of E{sub 2} on islet cells was linked to the functions of the estrogen receptor {alpha}. Notably, these protective effects of E{sub 2} on diabetic conditions were basically not observed when the STZ-treated rats had a more severe degree of islet damage and hyperglycemia. Taken together, we conclude that E{sub 2} can promote the regeneration of damaged pancreatic islets by stimulating {beta}-cell proliferation in diabetic rats, and this effect is accompanied by improvements in glucose tolerance and a decrease in plasma glucose levels. These findings suggest that oral administration of E{sub 2} may be beneficial in diabetic patients with an accelerated loss of islet {beta}-cells.

  10. Inter-domain tagging implicates caveolin-1 in insulin receptor trafficking and Erk signaling bias in pancreatic beta-cells

    PubMed Central

    Boothe, Tobias; Lim, Gareth E.; Cen, Haoning; Skovsø, Søs; Piske, Micah; Li, Shu Nan; Nabi, Ivan R.; Gilon, Patrick; Johnson, James D.

    2016-01-01

    Objective The role and mechanisms of insulin receptor internalization remain incompletely understood. Previous trafficking studies of insulin receptors involved fluorescent protein tagging at their termini, manipulations that may be expected to result in dysfunctional receptors. Our objective was to determine the trafficking route and molecular mechanisms of functional tagged insulin receptors and endogenous insulin receptors in pancreatic beta-cells. Methods We generated functional insulin receptors tagged with pH-resistant fluorescent proteins between domains. Confocal, TIRF and STED imaging revealed a trafficking pattern of inter-domain tagged insulin receptors and endogenous insulin receptors detected with antibodies. Results Surprisingly, interdomain-tagged and endogenous insulin receptors in beta-cells bypassed classical Rab5a- or Rab7-mediated endocytic routes. Instead, we found that removal of insulin receptors from the plasma membrane involved tyrosine-phosphorylated caveolin-1, prior to trafficking within flotillin-1-positive structures to lysosomes. Multiple methods of inhibiting caveolin-1 significantly reduced Erk activation in vitro or in vivo, while leaving Akt signaling mostly intact. Conclusions We conclude that phosphorylated caveolin-1 plays a role in insulin receptor internalization towards lysosomes through flotillin-1-positive structures and that caveolin-1 helps bias physiological beta-cell insulin signaling towards Erk activation. PMID:27110488

  11. Neogenesis and proliferation of {beta}-cells induced by human betacellulin gene transduction via retrograde pancreatic duct injection of an adenovirus vector

    SciTech Connect

    Tokui, Yae . E-mail: ytokui@imed2.med.osaka-u.ac.jp; Kozawa, Junji; Yamagata, Kazuya; Zhang, Jun; Ohmoto, Hiroshi; Tochino, Yoshihiro; Okita, Kohei; Iwahashi, Hiromi; Namba, Mitsuyoshi; Shimomura, Iichiro; Miyagawa, Jun-ichiro |

    2006-12-01

    Betacellulin (BTC) has been shown to have a role in the differentiation and proliferation of {beta}-cells both in vitro and in vivo. We administered a human betacellulin (hBTC) adenovirus vector to male ICR mice via retrograde pancreatic duct injection. As a control, we administered a {beta}-galactosidase adenovirus vector. In the mice, hBTC protein was mainly overexpressed by pancreatic duct cells. On immunohistochemical analysis, we observed features of {beta}-cell neogenesis as newly formed insulin-positive cells in the duct cell lining or islet-like cell clusters (ICCs) closely associated with the ducts. The BrdU labeling index of {beta}-cells was also increased by the betacellulin vector compared with that of control mice. These results indicate that hBTC gene transduction into adult pancreatic duct cells promoted {beta}-cell differentiation (mainly from duct cells) and proliferation of pre-existing {beta}-cells, resulting in an increase of the {beta}-cell mass that improved glucose tolerance in diabetic mice.

  12. ER stress and the decline and fall of pancreatic beta cells in type 1 diabetes

    PubMed Central

    Brozzi, Flora

    2016-01-01

    Components of the unfolded protein response (UPR) modulate beta cell inflammation and death in early type 1 diabetes (T1D). The UPR is a mechanism by which cells react to the accumulation of misfolded proteins in the endoplasmic reticulum (ER). It aims to restore cellular homeostasis, but in case of chronic or overwhelming ER stress the persistent activation of the UPR triggers apoptosis, contributing to the loss of beta cells in both T1D and type 2 diabetes. It remains to be determined how and why the transition from ‘physiological’ to ‘pathological’ UPR takes place. A key component of the UPR is the ER transmembrane protein IRE1α (inositol-requiring enzyme 1α). IRE1α activity is modulated by both intra-ER signals and by the formation of protein complexes at its cytosolic domain. The amplitude and duration of IRE1α signaling is critical for the transition between the adaptive and cell death programs, with particular relevance for the activation of the pro-apoptotic c-Jun N-terminal kinase (JNK) in beta cells. In the present review we discuss the available information on IRE1α-regulating proteins in beta cells and their downstream targets, and the important differences observed between cytokine-induced UPR in human and rodent beta cells. PMID:26899404

  13. Baculovirus p35 increases pancreatic {beta}-cell resistance to apoptosis

    SciTech Connect

    Hollander, Kenneth; Bar-Chen, Michal; Efrat, Shimon . E-mail: sefrat@post.tau.ac.il

    2005-07-01

    {beta}-cells die by apoptosis in type 1 diabetes as a result of autoimmune attack mediated by cytokines, and in type 2 diabetes by various perpetrators including human islet amyloid polypeptide (hIAPP). The cascade of apoptotic events induced by cytokines and hIAPP is mediated through caspases and reactive oxygen species. The baculovirus p35 protein is a potent anti-apoptotic agent shown to be effective in a variety of species and able to inhibit a number of apoptotic pathways. Here, we aimed at determining the protective potential of p35 in {beta}-cells exposed to cytokines and hIAPP, as well as the effects of p35 on {beta}-cell function. The p35 gene was introduced into {beta}TC-tet cells, a differentiated murine {beta}-cell line capable of undergoing inducible growth-arrest. Both proliferating and growth-arrested cells expressing p35 manifested increased resistance to cytokines and hIAPP, compared with control cells, as judged by cell viability, DNA fragmentation, and caspase-3 activity assays. p35 was significantly more protective in growth-arrested, compared with proliferating, cells. No significant differences were observed in proliferation and insulin content between cells expressing p35 and control cells. In contrast, p35 manifested a perturbing effect on glucose-induced insulin secretion. These findings suggest that p35 could be incorporated as part of a multi-pronged approach of immunoprotective strategies to provide protection from recurring autoimmunity for transplanted {beta}-cells, as well as in preventive gene therapy in type 1 diabetes. p35 may also be protective from {beta}-cell damage caused by hIAPP in type 2 diabetes.

  14. Restoring Mitochondrial Function: A Small Molecule-mediated Approach to Enhance Glucose Stimulated Insulin Secretion in Cholesterol Accumulated Pancreatic beta cells.

    PubMed

    Asalla, Suman; Girada, Shravan Babu; Kuna, Ramya S; Chowdhury, Debabrata; Kandagatla, Bhaskar; Oruganti, Srinivas; Bhadra, Utpal; Bhadra, Manika Pal; Kalivendi, Shasi Vardhan; Rao, Swetha Pavani; Row, Anupama; Ibrahim, A; Ghosh, Partha Pratim; Mitra, Prasenjit

    2016-01-01

    Dyslipidemia, particularly the elevated serum cholesterol levels, aggravate the pathophysiology of type 2 diabetes. In the present study we explored the relationship between fasting blood sugar and serum lipid parameters in human volunteers which revealed a significant linear effect of serum cholesterol on fasting blood glucose. Short term feeding of cholesterol enriched diet to rodent model resulted in elevated serum cholesterol levels, cholesterol accumulation in pancreatic islets and hyperinsulinemia with modest increase in plasma glucose level. To explore the mechanism, we treated cultured BRIN-BD11 pancreatic beta cells with soluble cholesterol. Our data shows that cholesterol treatment of cultured pancreatic beta cells enhances total cellular cholesterol. While one hour cholesterol exposure enhances insulin exocytosis, overnight cholesterol accumulation in cultured pancreatic beta cells affects cellular respiration, and inhibits Glucose stimulated insulin secretion. We further report that (E)-4-Chloro-2-(1-(2-(2,4,6-trichlorophenyl) hydrazono) ethyl) phenol (small molecule M1) prevents the cholesterol mediated blunting of cellular respiration and potentiates Glucose stimulated insulin secretion which was abolished in pancreatic beta cells on cholesterol accumulation. PMID:27282931

  15. Restoring Mitochondrial Function: A Small Molecule-mediated Approach to Enhance Glucose Stimulated Insulin Secretion in Cholesterol Accumulated Pancreatic beta cells

    PubMed Central

    Asalla, Suman; Girada, Shravan Babu; Kuna, Ramya S.; Chowdhury, Debabrata; Kandagatla, Bhaskar; Oruganti, Srinivas; Bhadra, Utpal; Bhadra, Manika Pal; Kalivendi, Shasi Vardhan; Rao, Swetha Pavani; Row, Anupama; Ibrahim, A; Ghosh, Partha Pratim; Mitra, Prasenjit

    2016-01-01

    Dyslipidemia, particularly the elevated serum cholesterol levels, aggravate the pathophysiology of type 2 diabetes. In the present study we explored the relationship between fasting blood sugar and serum lipid parameters in human volunteers which revealed a significant linear effect of serum cholesterol on fasting blood glucose. Short term feeding of cholesterol enriched diet to rodent model resulted in elevated serum cholesterol levels, cholesterol accumulation in pancreatic islets and hyperinsulinemia with modest increase in plasma glucose level. To explore the mechanism, we treated cultured BRIN-BD11 pancreatic beta cells with soluble cholesterol. Our data shows that cholesterol treatment of cultured pancreatic beta cells enhances total cellular cholesterol. While one hour cholesterol exposure enhances insulin exocytosis, overnight cholesterol accumulation in cultured pancreatic beta cells affects cellular respiration, and inhibits Glucose stimulated insulin secretion. We further report that (E)-4-Chloro-2-(1-(2-(2,4,6-trichlorophenyl) hydrazono) ethyl) phenol (small molecule M1) prevents the cholesterol mediated blunting of cellular respiration and potentiates Glucose stimulated insulin secretion which was abolished in pancreatic beta cells on cholesterol accumulation. PMID:27282931

  16. βIV-Spectrin and CaMKII facilitate Kir6.2 regulation in pancreatic beta cells

    PubMed Central

    Kline, Crystal F.; Wright, Patrick J.; Koval, Olha M.; Zmuda, Erik J.; Johnson, Benjamin L.; Anderson, Mark E.; Hai, Tsonwin; Hund, Thomas J.; Mohler, Peter J.

    2013-01-01

    Identified over a dozen years ago in the brain and pancreatic islet, βIV-spectrin is critical for the local organization of protein complexes throughout the nervous system. βIV-Spectrin targets ion channels and adapter proteins to axon initial segments and nodes of Ranvier in neurons, and βIV-spectrin dysfunction underlies ataxia and early death in mice. Despite advances in βIV-spectrin research in the nervous system, its role in pancreatic islet biology is unknown. Here, we report that βIV-spectrin serves as a multifunctional structural and signaling platform in the pancreatic islet. We report that βIV-spectrin directly associates with and targets the calcium/calmodulin-dependent protein kinase II (CaMKII) in pancreatic islets. In parallel, βIV-spectrin targets ankyrin-B and the ATP-sensitive potassium channel. Consistent with these findings, βIV-spectrin mutant mice lacking CaMKII- or ankyrin-binding motifs display selective loss of expression and targeting of key protein components, including CaMKIIδ. βIV-Spectrin–targeted CaMKII directly phosphorylates the inwardly-rectifying potassium channel, Kir6.2 (alpha subunit of KATP channel complex), and we identify the specific residue, Kir6.2 T224, responsible for CaMKII-dependent regulation of KATP channel function. CaMKII-dependent phosphorylation alters channel regulation resulting in KATP channel inhibition, a cellular phenotype consistent with aberrant insulin regulation. Finally, we demonstrate aberrant KATP channel phosphorylation in βIV-spectrin mutant mice. In summary, our findings establish a broader role for βIV-spectrin in regulation of cell membrane excitability in the pancreatic islet, define the pathway for CaMKII local control in pancreatic beta cells, and identify the mechanism for CaMKII-dependent regulation of KATP channels. PMID:24101510

  17. βIV-Spectrin and CaMKII facilitate Kir6.2 regulation in pancreatic beta cells.

    PubMed

    Kline, Crystal F; Wright, Patrick J; Koval, Olha M; Zmuda, Erik J; Johnson, Benjamin L; Anderson, Mark E; Hai, Tsonwin; Hund, Thomas J; Mohler, Peter J

    2013-10-22

    Identified over a dozen years ago in the brain and pancreatic islet, βIV-spectrin is critical for the local organization of protein complexes throughout the nervous system. βIV-Spectrin targets ion channels and adapter proteins to axon initial segments and nodes of Ranvier in neurons, and βIV-spectrin dysfunction underlies ataxia and early death in mice. Despite advances in βIV-spectrin research in the nervous system, its role in pancreatic islet biology is unknown. Here, we report that βIV-spectrin serves as a multifunctional structural and signaling platform in the pancreatic islet. We report that βIV-spectrin directly associates with and targets the calcium/calmodulin-dependent protein kinase II (CaMKII) in pancreatic islets. In parallel, βIV-spectrin targets ankyrin-B and the ATP-sensitive potassium channel. Consistent with these findings, βIV-spectrin mutant mice lacking CaMKII- or ankyrin-binding motifs display selective loss of expression and targeting of key protein components, including CaMKIIδ. βIV-Spectrin-targeted CaMKII directly phosphorylates the inwardly-rectifying potassium channel, Kir6.2 (alpha subunit of KATP channel complex), and we identify the specific residue, Kir6.2 T224, responsible for CaMKII-dependent regulation of KATP channel function. CaMKII-dependent phosphorylation alters channel regulation resulting in KATP channel inhibition, a cellular phenotype consistent with aberrant insulin regulation. Finally, we demonstrate aberrant KATP channel phosphorylation in βIV-spectrin mutant mice. In summary, our findings establish a broader role for βIV-spectrin in regulation of cell membrane excitability in the pancreatic islet, define the pathway for CaMKII local control in pancreatic beta cells, and identify the mechanism for CaMKII-dependent regulation of KATP channels. PMID:24101510

  18. CREB is a regulatory target for the protein kinase Akt/PKB in the differentiation of pancreatic ductal cells into islet {beta}-cells mediated by hepatocyte growth factor

    SciTech Connect

    Li, Xin-Yu; Zhan, Xiao-Rong; Liu, Xiao-Min; Wang, Xiao-Chen

    2011-01-14

    Research highlights: {yields} CREB is a regulatory target for the protein kinase Akt/PKB in pancreatic duct cells. {yields} Activation of the PI3K/AKT/CREB pathway plays a critical role in the HGF-mediated differentiation of pancreatic duct cells in vivo. {yields} CREB was causally linked to the expression of transcription factors during PDEC differentiation induced by HGF. -- Abstract: We have previously reported that the PI3K/Akt signaling pathway is involved in hepatocyte growth factor (HGF)-induced differentiation of adult rat pancreatic ductal epithelial cells (PDECs) into islet {beta}-cells in vitro. The transcription factor CREB is one of the downstream key effectors of the PI3K/Akt signaling pathway. Recent studies showing that CREB is required for the survival of certain cell types prompted us to examine whether CREB is a nuclear target for activation via the HGF-dependent Ser/Thr kinase Akt/PKB in the differentiation of pancreatic duct cell into islet {beta}-cells. In this study, we first attempted to examine whether HGF modulates the Akt-dependent activation of target gene CREB and then investigated whether CREB activity affects the differentiation of HGF-induced PDECs. Finally, we studied the role of CREB in modulating the expression of transcription factors in PDECs during the differentiation of HGF-induced PDECs. Our results demonstrated that CREB is a regulatory target for the protein kinase Akt/PKB in the differentiation of pancreatic ductal cells into islet {beta}-cells mediated by HGF.

  19. Glucose tolerance normalization following transplantation of pig pancreatic primordia into non-immunosuppressed diabetic ZDF rats.

    PubMed

    Rogers, Sharon A; Chen, Feng; Talcott, Mike; Liapis, Helen; Hammerman, Marc R

    2006-11-01

    Pancreas or pancreatic islet transplantation in humans is limited by organ availability, and success of the latter is negatively impacted upon by tissue loss post-transplantation and limited potential for expansion of beta cells. A way to overcome the supply and expansion problems is to xenotransplant embryonic tissue. Previously, we have shown that beta cells originating from embryonic day (E) 28 (E28) pig pancreatic primordia transplanted into the mesentery of streptozotocin-diabetic (type 1) Lewis rats engraft without the need for host immune-suppression and normalize glucose tolerance. Here we show long-term engraftment of pig beta cells within liver, pancreas and mesenteric lymph nodes post-transplantation of E28 pig pancreatic primordia into diabetic ZDF rats, a model for type 2 diabetes. Porcine insulin is present in circulation after an oral glucose load. Glucose tolerance is normalized in transplanted ZDF hosts and insulin sensitivity restored in formerly diabetic ZDF males. Release of porcine insulin in vitro from tissue originating in transplanted rats occurs within 1 min of glucose stimulation characteristic of first-phase secretion from beta cells. Of potential importance for application of this transplantation technology to treatment of type 2 diabetes in humans and confirmatory of our previous findings in Lewis rats, no host immunosuppression is required for engraftment of E28 pig pancreatic primordia. PMID:17138051

  20. Analysis of the noise-induced bursting-spiking transition in a pancreatic beta-cell model.

    PubMed

    Aguirre, Jacobo; Mosekilde, Erik; Sanjuán, Miguel A F

    2004-04-01

    A stochastic model of the electrophysiological behavior of the pancreatic beta cell is studied, as a paradigmatic example of a bursting biological cell embedded in a noisy environment. The analysis is focused on the distortion that a growing noise causes to the basic properties of the membrane potential signals, such as their periodic or chaotic nature, and their bursting or spiking behavior. We present effective computational tools to obtain as much information as possible from these signals, and we suggest that the methods could be applied to real time series. Finally, a universal dependence of the main characteristics of the membrane potential on the size of the considered cell cluster is presented. PMID:15169046

  1. Endocytosis of secretory granules in mouse pancreatic beta-cells evoked by transient elevation of cytosolic calcium.

    PubMed Central

    Eliasson, L; Proks, P; Ammälä, C; Ashcroft, F M; Bokvist, K; Renström, E; Rorsman, P; Smith, P A

    1996-01-01

    1. To investigate the mechanisms regulating the reuptake of secretory granule membranes following regulated exocytosis, we have monitored changes in cell capacitance in single pancreatic beta-cells. 2. Membrane retrieval (endocytosis) occurred both in a continuous manner and in abrupt steps, corresponding to the simultaneous retrieval of 50-100 granules. The large endocytotic steps were associated with a conductance change of about 1 nS which we attribute to the formation of a fission pore with a pore radius of approximately 1 nm. 3. In some cells, we observed large amplitude capacitance fluctuations, suggesting that aggregates of granules are connected to the plasma membrane by a single pore and are subsequently retrieved as a single unit. 4. Endocytosis was evoked by elevation of cytosolic [Ca2+]i, but once initiated, a sustained increase in [Ca2+]i was not required for endocytosis to continue. 5. The [Ca2+]i dependence of exo- and endocytosis was studied by photorelease of Ca2+ from the 'caged' precursor Ca(2+)-nitrophenyl-EGTA (Ca(2+)-NP-EGTA). Both exo- and endocytosis were initiated at between 0.5 and 2 microM Cai(2+). The rate of endocytosis saturated above 2 microM Cai(2+), whereas exocytosis continued to increase up to 4 microM Cai(2+). The maximum rate of endocytosis was < 25% of that of exocytosis. 6. Unlike exocytosis, endocytosis proceeded equally well in the presence or absence of Mg-ATP. 7. Our data indicate that in the pancreatic beta-cell, exocytosis and endocytosis are regulated by different mechanisms. Images Figure 6 Figure 8 PMID:8799897

  2. Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis

    PubMed Central

    Fridlyand, Leonid E.; Philipson, Louis H.

    2016-01-01

    Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger

  3. In vitro effects of mycophenolic acid on survival, function, and gene expression of pancreatic beta-cells.

    PubMed

    Gallo, R; Natale, M; Vendrame, F; Boggi, U; Filipponi, F; Marchetti, P; Laghi Pasini, F; Dotta, F

    2012-12-01

    Post-transplant diabetes mellitus represents an important complication of prolonged immunosuppressive treatment after solid organ transplantation. The immunosuppressive toxicity, responsible for a persistent impairment of glucose metabolism in pancreatic islet-transplanted patients, is mainly attributed to calcineurin inhibitors and steroids, while other immunosuppressive molecules (azathioprine and mycophenolic acid, MPA) are considered not to have a toxic effect. In the present study, in vitro effects of MPA have been investigated in mouse beta-cell lines (βTC-1 and βTC-6) and in purified human pancreatic islets. βTC-1, βTC-6, and human pancreatic islets were exposed to various concentrations of MPA for different times. Consequently, we evaluated the viability, the induction of apoptosis, the glucose-stimulated insulin secretion, and the expression of β-cell function genes (Isl1, Pax6, Glut-2, glucokinase) and apoptosis-related genes (Bax and Bcl2). βTC-1, βTC-6, and human islets treated, respectively, for 48 and 72 h with 15-30 nM MPA showed altered islet architecture, as compared with control cells. We observed for βTC-1 and βTC-6 almost 70% reduction in cell viability; three to sixfold induction of TUNEL/apoptotic-positive cells quantified by FACS analysis. A twofold increase in apoptotic cells was observed in human islets after MPA exposure associated with strong inhibition of glucose-stimulated insulin secretion. Furthermore, we showed significant down-regulation of gene expression of molecules involved in β-cell function and increase rate between Bax/Bcl2. Our data demonstrate that MPA has an in vitro diabetogenic effect interfering at multiple levels with survival and function of murine and human pancreatic β-cells. PMID:22249339

  4. The transcription factors Nkx6.1 and Nkx6.2 possess equivalent activities in promoting beta-cell fate specification in Pdx1+ pancreatic progenitor cells.

    PubMed

    Nelson, Shelley B; Schaffer, Ashleigh E; Sander, Maike

    2007-07-01

    Despite much progress in identifying transcriptional regulators that control the specification of the different pancreatic endocrine cell types, the spatiotemporal aspects of endocrine subtype specification have remained largely elusive. Here, we address the mechanism by which the transcription factors Nkx6.1 (Nkx6-1) and Nkx6.2 (Nkx6-2) orchestrate development of the endocrine alpha- and beta-cell lineages. Specifically, we assayed for the rescue of insulin-producing beta-cells in Nkx6.1 mutant mice upon restoring Nkx6 activity in select progenitor cell populations with different Nkx6-expressing transgenes. Beta-cell formation and maturation was restored when Nkx6.1 was expressed in multipotential Pdx1(+) pancreatic progenitors, whereas no rescue was observed upon expression in committed Ngn3(+) (Neurog3(+)) endocrine progenitors. Although not excluding additional roles downstream of Ngn3, this finding suggests a first requirement for Nkx6.1 in specifying beta-cell progenitors prior to Ngn3 activation. Surprisingly, although Nkx6.2 only compensates for Nkx6.1 in alpha-but not in beta-cell development in Nkx6.1(-/-) mice, a Pdx1-promoter-driven Nkx6.2 transgene had the same ability to rescue beta-cells as the Pdx1-Nkx6.1 transgene. This demonstrates that the distinct requirements for Nkx6.1 and Nkx6.2 in endocrine differentiation are a consequence of their divergent spatiotemporal expression domains rather than their biochemical activities and implies that both Nkx6.1 and Nkx6.2 possess alpha- and beta-cell-specifying activities. PMID:17537793

  5. Is Transforming Stem Cells to Pancreatic Beta Cells Still the Holy Grail for Type 2 Diabetes?

    PubMed

    Kahraman, Sevim; Okawa, Erin R; Kulkarni, Rohit N

    2016-08-01

    Diabetes is a progressive disease affecting millions of people worldwide. There are several medications and treatment options to improve the life quality of people with diabetes. One of the strategies for the treatment of diabetes could be the use of human pluripotent stem cells or induced pluripotent stem cells. The recent advances in differentiation of stem cells into insulin-secreting beta-like cells in vitro make the transplantation of the stem cell-derived beta-like cells an attractive approach for treatment of type 1 and type 2 diabetes. While stem cell-derived beta-like cells provide an unlimited cell source for beta cell replacement therapies, these cells can also be used as a platform for drug screening or modeling diseases. PMID:27313072

  6. GLUT2 (SLC2A2) is not the principal glucose transporter in human pancreatic beta cells: implications for understanding genetic association signals at this locus.

    PubMed

    McCulloch, Laura J; van de Bunt, Martijn; Braun, Matthias; Frayn, Keith N; Clark, Anne; Gloyn, Anna L

    2011-12-01

    SLC2A2 encoding glucose transporter -2 (GLUT2) acts as the primary glucose transporter and sensor in rodent pancreatic islets and is widely assumed to play a similar role in humans. In healthy adults SLC2A2 variants are associated with elevated fasting plasma glucose (fpg) concentrations but physiological characterisation does not support a defect in pancreatic beta-cell function. Interspecies differences can create barriers for the follow up of disease association signals. We hypothesised that GLUT2 is not the principal glucose transporter in human beta-cells and that SLC2A2 variants exert their effect on fpg levels through defects in other tissues. SLC2A1-4 (GLUT 1-4) mRNA expression levels were determined in human and mouse islets, beta-cells, liver, muscle and adipose tissue by qRT-PCR whilst GLUT1-3 protein levels were examined by immunohistochemistry. The presence of all three glucose transporters was demonstrated in human and mouse islets and purified beta-cells. Quantitative expression profiling demonstrated that Slc2a2 is the predominant glucose transporter (expression >10 fold higher that Slc2a1) in mouse islets whilst SLC2A1 and SLC2A3 predominate in both human islets and beta-cells (expression 2.8 and 2.7 fold higher than SLC2A2 respectively). Our data therefore suggest that GLUT2 is unlikely to be the principal glucose transporter in human beta-cells and that SLC2A2 defects in other metabolic tissues drive the observed differences in glucose levels between carriers of SLC2A2 variants. Direct extrapolation from rodent to human islet glucose transporter activity is unlikely to be appropriate. PMID:21920790

  7. Exendin-4 Protects Mitochondria from Reactive Oxygen Species Induced Apoptosis in Pancreatic Beta Cells

    PubMed Central

    Li, Zhen; Zhou, Zhiguang; Huang, Gan; Hu, Fang; Xiang, Yufei; He, Lining

    2013-01-01

    Objective Mitochondrial oxidative stress is the basis for pancreatic β-cell apoptosis and a common pathway for numerous types of damage, including glucotoxicity and lipotoxicity. We cultivated mice pancreatic β-cell tumor Min6 cell lines in vitro and observed pancreatic β-cell apoptosis and changes in mitochondrial function before and after the addition of Exendin-4. Based on these observations, we discuss the protective role of Exendin-4 against mitochondrial oxidative damage and its relationship with Ca2+-independent phospholipase A2. Methods We established a pancreatic β-cell oxidative stress damage model using Min6 cell lines cultured in vitro with tert-buty1 hydroperoxide and hydrogen peroxide. We then added Exendin-4 to observe changes in the rate of cell apoptosis (Annexin-V-FITC-PI staining flow cytometry and DNA ladder). We detected the activity of the caspase 3 and 8 apoptotic factors, measured the mitochondrial membrane potential losses and reactive oxygen species production levels, and detected the expression of cytochrome c and Smac/DLAMO in the cytosol and mitochondria, mitochondrial Ca2-independent phospholipase A2 and Ca2+-independent phospholipase A2 mRNA. Results The time-concentration curve showed that different percentages of apoptosis occurred at different time-concentrations in tert-buty1 hydroperoxide- and hydrogen peroxide-induced Min6 cells. Incubation with 100 µmol/l of Exendin-4 for 48 hours reduced the Min6 cell apoptosis rate (p<0.05). The mitochondrial membrane potential loss and total reactive oxygen species levels decreased (p<0.05), and the release of cytochrome c and Smac/DLAMO from the mitochondria was reduced. The study also showed that Ca2+-independent phospholipase A2 activity was positively related to Exendin-4 activity. Conclusion Exendin-4 reduces Min6 cell oxidative damage and the cell apoptosis rate, which may be related to Ca2-independent phospholipase A2. PMID:24204601

  8. Extracellular ATP-induced nuclear Ca{sup 2+} transient is mediated by inositol 1,4,5-trisphosphate receptors in mouse pancreatic {beta}-cells

    SciTech Connect

    Chen, Zheng; Li, Zhengzheng; Peng, Gong; Chen, Xiaoli; Yin, Wenxuan; Kotlikoff, Michael I.; Yuan, Zeng-qiang; Ji, Guangju

    2009-05-01

    Extracellular ATP (eATP) induces an intracellular Ca{sup 2+} transient by activating phospholipase C (PLC)-associated P2X4 purinergic receptors, leading to production of inositol 1,4,5-trisphosphate (IP3) and subsequent Ca{sup 2+} release from intracellular stores in mouse pancreatic {beta}-cells. Using laser scanning confocal microscopy, Ca{sup 2+} indicator fluo-4 AM, and the cell permeable nuclear indicator Hoechst 33342, we examined the properties of eATP-induced Ca{sup 2+} release in pancreatic {beta}-cell nuclei. eATP induced a higher nuclear Ca{sup 2+} transient in pancreatic {beta}-cell nuclei than in the cytosol. After pretreatment with thapsigargin (TG), an inhibitor of sarco-endoplasmic reticulum Ca{sup 2+}-ATPase (SERCA) pumps, the amplitude of eATP-induced Ca{sup 2+} transients in the nucleus was still much higher than those in the cytosol. This effect of eATP was not altered by inhibition of either the plasma membrane Ca{sup 2+}-ATPase (PMCA) or the plasma membrane Na{sup +}/Ca{sup 2+} exchanger (NCX) by LaCl{sub 3} or by replacement of Na{sup +} with N-Methyl-Glucosamine. eATP-induced nuclear Ca{sup 2+} transients were abolished by a cell-permeable IP3R inhibitor, 2-aminoethoxydiphenyl borate (2-APB), but were not blocked by the ryanodine receptor (RyR) antagonist ryanodine. Immunofluorescence studies showed that IP3Rs are expressed on the nuclear envelope of pancreatic {beta}-cells. These results indicate that eATP triggers nuclear Ca{sup 2+} transients by mobilizing a nuclear Ca{sup 2+} store via nuclear IP3Rs.

  9. Hormetic and regulatory effects of lipid peroxidation mediators in pancreatic beta cells.

    PubMed

    Maulucci, Giuseppe; Daniel, Bareket; Cohen, Ofir; Avrahami, Yossef; Sasson, Shlomo

    2016-06-01

    proliferator-activated receptor δ (PPARδ) in vascular endothelial cells and insulin secreting beta cells, promote such adaptive responses to ameliorate detrimental effects of high glucose and diabetes-like conditions. In addition, due to the electrophilic nature of these reactive aldehydes they form covalent adducts with electronegative moieties in proteins, phosphatidylethanolamine and nucleotides. Normally these non-enzymatic modifications are maintained below the cytotoxic range due to efficient cellular neutralization processes of 4-hydroxyalkenals. The major neutralizing enzymes include fatty aldehyde dehydrogenase (FALDH), aldose reductase (AR) and alcohol dehydrogenase (ADH), which transform the aldehyde to the corresponding carboxylic acid or alcohols, respectively, or by biding to the thiol group in glutathione (GSH) by the action of glutathione-S-transferase (GST). This review describes the hormetic and cytotoxic roles of oxygen free radicals and 4-hydroxyalkenals in beta cells exposed to nutritional challenges and the cellular mechanisms they employ to maintain their level at functional range below the cytotoxic threshold. PMID:27012748

  10. Effects of low intensity laser acupoint irradiation on inhibiting islet beta-cell apoptosis in rats with type 2 diabetes

    NASA Astrophysics Data System (ADS)

    Xiong, Guoxin; Xiong, Leilei; Li, Xinzhong

    2016-09-01

    To investigate the effects of low intensity semiconductor laser acupoint irradiation on inhibiting islet beta-cell apoptosis in rats with type 2 diabetes, a method using a high-fat diet and low-dose intraperitoneal injections of streptozotocin established a type 2 diabetes mellitus rat model. Model rats were randomly divided into a laser acupoint irradiation group, rosiglitazone control group, and placebo group; each group had 10 rats. In addition, 10 normal male rats were selected for the normal control group. The Housanli, Neiting and Yishu acupoints of the rats in the laser acupoint irradiation group were irradiated with a 10 mW semiconductor laser; each point was irradiated for 15 min, once every 2 d over 28 d, for a total of 14 episodes of irradiation. The rosiglitazone group rats were given rosiglitazone (0.2 mg kg‑1) intragastrically; the placebo group rats were given 0.9% brine (0.2 mg kg‑1) intragastrically, once daily, for four consecutive weeks. The change of fasting blood glucose was determined before and after each treatment. The islet beta-cell apoptosis was determined. The islet beta-cell apoptosis rates of the laser acupoint irradiation group and the rosiglitazone group were significantly lower than the rate of the placebo group. Even though the rate was lower in the laser acupoint irradiation group than in the rosiglitazone group, there was no significant difference between them. It is shown that acupoint irradiation with a semiconductor laser can effectively inhibit islet beta-cell apoptosis in rats with type 2 diabetes.

  11. Characterization of Phospholipids in Insulin Secretory Granules and Mitochondria in Pancreatic Beta Cells and Their Changes with Glucose Stimulation*

    PubMed Central

    MacDonald, Michael J.; Ade, Lacmbouh; Ntambi, James M.; Ansari, Israr-Ul H.; Stoker, Scott W.

    2015-01-01

    The lipid composition of insulin secretory granules (ISG) has never previously been thoroughly characterized. We characterized the phospholipid composition of ISG and mitochondria in pancreatic beta cells without and with glucose stimulation. The phospholipid/protein ratios of most phospholipids containing unsaturated fatty acids were higher in ISG than in whole cells and in mitochondria. The concentrations of negatively charged phospholipids, phosphatidylserine, and phosphatidylinositol in ISG were 5-fold higher than in the whole cell. In ISG phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, and sphingomyelin, fatty acids 12:0 and 14:0 were high, as were phosphatidylserine and phosphatidylinositol containing 18-carbon unsaturated FA. With glucose stimulation, the concentration of many ISG phosphatidylserines and phosphatidylinositols increased; unsaturated fatty acids in phosphatidylserine increased; and most phosphatidylethanolamines, phosphatidylcholines, sphingomyelins, and lysophosphatidylcholines were unchanged. Unsaturation and shorter fatty acid length in phospholipids facilitate curvature and fluidity of membranes, which favors fusion of membranes. Recent evidence suggests that negatively charged phospholipids, such as phosphatidylserine, act as coupling factors enhancing the interaction of positively charged regions in SNARE proteins in synaptic or secretory vesicle membrane lipid bilayers with positively charged regions in SNARE proteins in the plasma membrane lipid bilayer to facilitate docking of vesicles to the plasma membrane during exocytosis. The results indicate that ISG phospholipids are in a dynamic state and are consistent with the idea that changes in ISG phospholipids facilitate fusion of ISG with the plasma membrane-enhancing glucose-stimulated insulin exocytosis. PMID:25762724

  12. Glucocorticoid overexposure in neonatal life alters pancreatic beta-cell function in newborn foals.

    PubMed

    Jellyman, J K; Allen, V L; Holdstock, N B; Fowden, A L

    2013-01-01

    Studies in humans and animals have linked abnormal programming of adult tissue function to excess glucocorticoids during perinatal development. The current study investigated the hypothesis that physiological variations in glucocorticoid concentrations during early neonatal life of the foal alter the secretory responses of the pancreatic β cells 2 and 12 wk after treatment. Spontaneously delivered foals received either saline or long-acting ACTH for 5 d from 1 d after birth to maintain an endogenous rise in cortisol concentrations. Starting at d 10, pancreatic β cell function was studied using an intravenous (i.v.) glucose tolerance test, an i.v. arginine challenge, and an i.v. tolbutamide challenge. The maximum increment in plasma insulin achieved in response to exogenous glucose was less in ACTH-treated foals at both 2 and 12 wk of age (P<0.05). By 12 wk of age, developmental changes also occurred in the magnitude and biphasic pattern of glucose-stimulated insulin release. The area under the insulin curve during the early phase of insulin secretion (0 to 30 min) was not different between the 2- and 12-wk-old animals but was significantly greater during the later phase (30 to 120 min) at 12 wk than at 2 wk (P<0.05). Arginine infusion induced a brief 5 to 15 min increase in plasma concentrations of insulin that was not different in saline- and ACTH-treated foals. The β-cell response to tolbutamide infusion was rapid and monophasic, and there was no difference (P>0.05) in the area under the insulin curve with treatment at 2 or at 12 wk. However, after tolbutamide, plasma insulin concentrations remained increased for a longer period in the ACTH-treated than in the saline-treated foals at 12 wk of age (P<0.05). Hence, this is the first study to show altered pancreatic β-cell function after ACTH-induced glucocorticoid overexposure during early postnatal life in foals. PMID:23100584

  13. Protein Fractions from Korean Mistletoe (Viscum Album coloratum) Extract Induce Insulin Secretion from Pancreatic Beta Cells

    PubMed Central

    Kim, Jong-Bae

    2014-01-01

    Mistletoe (Viscum Album coloratum) has been known as a medicinal plant in European and Asian countries. Recent data show that biological activity of mistletoe alleviates hypertension, heart disease, renal failure, and cancer development. In this study, we report the antidiabetic effect of Korean mistletoe extract (KME). KME treatments enhanced the insulin secretion from the pancreatic β-cell without any effects of cytotoxicity. PDX-1 and beta2/neuroD known as transcription factors that regulate the expression of insulin gene were upregulated by treatment of the KME protein fractions isolated by ion-exchange chromatography after ammonium sulfate precipitation. Furthermore, these KME protein fractions significantly lowered the blood glucose level and the volume of drinking water in alloxan induced hyperglycemic mice. Taken together with the findings, it provides new insight that KME might be served as a useful source for the development of medicinal reagent to reduce blood glucose level of type I diabetic patients. PMID:24959189

  14. Guiding pancreatic beta cells to target electrodes in a whole-cell biosensor for diabetes.

    PubMed

    Pedraza, Eileen; Karajić, Aleksandar; Raoux, Matthieu; Perrier, Romain; Pirog, Antoine; Lebreton, Fanny; Arbault, Stéphane; Gaitan, Julien; Renaud, Sylvie; Kuhn, Alexander; Lang, Jochen

    2015-10-01

    We are developing a cell-based bioelectronic glucose sensor that exploits the multi-parametric sensing ability of pancreatic islet cells for the treatment of diabetes. These cells sense changes in the concentration of glucose and physiological hormones and immediately react by generating electrical signals. In our sensor, signals from multiple cells are recorded as field potentials by a micro-electrode array (MEA). Thus, cell response to various factors can be assessed rapidly and with high throughput. However, signal quality and consequently overall sensor performance rely critically on close cell-electrode proximity. Therefore, we present here a non-invasive method of further exploiting the electrical properties of these cells to guide them towards multiple micro-electrodes via electrophoresis. Parameters were optimized by measuring the cell's zeta potential and modeling the electric field distribution. Clonal and primary mouse or human β-cells migrated directly to target electrodes during the application of a 1 V potential between MEA electrodes for 3 minutes. The morphology, insulin secretion, and electrophysiological characteristics were not altered compared to controls. Thus, cell manipulation on standard MEAs was achieved without introducing any external components and while maintaining the performance of the biosensor. Since the analysis of the cells' electrical activity was performed in real time via on-chip recording and processing, this work demonstrates that our biosensor is operational from the first step of electrically guiding cells to the final step of automatic recognition. Our favorable results with pancreatic islets, which are highly sensitive and fragile cells, are encouraging for the extension of this technique to other cell types and microarray devices. PMID:26282013

  15. Fluorescence microscopy studies with a fluorescent glibenclamide derivative, a high-affinity blocker of pancreatic beta-cell ATP-sensitive K+ currents.

    PubMed

    Zünkler, Bernd J; Wos-Maganga, Maria; Panten, Uwe

    2004-04-15

    Hypoglycemic sulfonylureas (e.g. tolbutamide, glibenclamide) exert their stimulatory effects on pancreatic beta-cells by closure of ATP-sensitive K(+) (K(ATP)) channels. Pancreatic K(ATP) channels are composed of two subunits, a pore-forming inwardly rectifying K(+) channel (Kir6.2) subunit and a regulatory subunit (the sulfonylurea receptor of subtype 1 (SUR1)) in a (SUR1/Kir6.2)(4) stoichiometry. The aim of the present study was to characterize the interaction of green-fluorescent 3-[3-(4,4 difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-S-indacen-3-yl)propanamido] glibenclamide (Bodipy-glibenclamide) with pancreatic beta-cell K(ATP) channels using patch-clamp and fluorescence microscopy techniques. Bodipy-glibenclamide inhibited K(ATP) currents from the clonal insulinoma cell line RINm5F half-maximally at a concentration of 0.6nM. Using laser-scanning confocal microscopy Bodipy-glibenclamide was shown to induce a diffuse fluorescence across the RINm5F cell, but only about 17% of total Bodipy-glibenclamide-induced fluorescence intensity in RINm5F cells was due to specific binding to SUR1. Using fluorescence correlation spectroscopy, it could be demonstrated that the fluorescence label contributes to the protein binding and, therefore, possibly also to the non-specific binding of Bodipy-glibenclamide observed in RINm5F cells. Specific binding of Bodipy-glibenclamide to SUR1 in RINm5F cells might be localized to different intracellular structures (nuclear envelope, endoplasmic reticulum, Golgi compartment, insulin secretory granules) as well as to the plasma membrane. In conclusion, Bodipy-glibenclamide is a high-affinity blocker of pancreatic beta-cell K(ATP) currents and can be used for visualizing SUR1 in intact pancreatic beta-cells, although non-specific binding must be taken into account in confocal microscopy experiments on intact beta-cells. PMID:15041461

  16. Immune Intervention and Preservation of Pancreatic Beta Cell Function in Type 1 Diabetes.

    PubMed

    Simmons, Kimber M; Gottlieb, Peter A; Michels, Aaron W

    2016-10-01

    Type 1 diabetes (T1D) results from the immune-mediated destruction of insulin-producing β cells located within the pancreatic islets of Langerhans. The autoimmune process leads to a deficiency in insulin production and resultant hyperglycemia requiring lifelong treatment with insulin administration. T1D continues to dramatically increase in incidence, especially in young children. Substantial knowledge surrounding human disease pathogenesis exists, such that T1D is now predictable with the measurement of antibodies in the peripheral blood directed against insulin and other β cell proteins. With the ability to predict, it naturally follows that T1D should be preventable. As such, over the last two decades, numerous well-controlled clinical trials have been completed attempting to prevent diabetes onset or maintain residual β cell function after clinical onset, all providing relatively disappointing results. Here, we review the T1D prevention efforts, the current landscape of clinical therapies, and end with a discussion regarding the future outlook for preventing T1D. PMID:27558810

  17. Activation of PPAR{delta} up-regulates fatty acid oxidation and energy uncoupling genes of mitochondria and reduces palmitate-induced apoptosis in pancreatic {beta}-cells

    SciTech Connect

    Wan, Jun; Jiang, Li; Lue, Qingguo; Ke, Linqiu; Li, Xiaoyu; Tong, Nanwei

    2010-01-15

    Recent evidence indicates that decreased oxidative capacity, lipotoxicity, and mitochondrial aberrations contribute to the development of insulin resistance and type 2 diabetes. The goal of this study was to investigate the effects of peroxisome proliferator-activated receptor {delta} (PPAR{delta}) activation on lipid oxidation, mitochondrial function, and insulin secretion in pancreatic {beta}-cells. After HIT-T15 cells (a {beta}-cell line) were exposed to high concentrations of palmitate and GW501516 (GW; a selective agonist of PPAR{delta}), we found that administration of GW increased the expression of PPAR{delta} mRNA. GW-induced activation of PPAR{delta} up-regulated carnitine palmitoyltransferase 1 (CPT1), long-chain acyl-CoA dehydrogenase (LCAD), pyruvate dehydrogenase kinase 4 (PDK4), and uncoupling protein 2 (UCP2); alleviated mitochondrial swelling; attenuated apoptosis; and reduced basal insulin secretion induced by increased palmitate in HIT cells. These results suggest that activation of PPAR{delta} plays an important role in protecting pancreatic {beta}-cells against aberrations caused by lipotoxicity in metabolic syndrome and diabetes.

  18. Cdk5 inhibitory peptide (CIP) inhibits Cdk5/p25 activity induced by high glucose in pancreatic beta cells and recovers insulin secretion from p25 damage.

    PubMed

    Zheng, Ya-Li; Li, Congyu; Hu, Ya-Fang; Cao, Li; Wang, Hui; Li, Bo; Lu, Xiao-Hua; Bao, Li; Luo, Hong-Yan; Shukla, Varsha; Amin, Niranjana D; Pant, Harish C

    2013-01-01

    Cdk5/p25 hyperactivity has been demonstrated to lead to neuron apoptosis and degenerations. Chronic exposure to high glucose (HG) results in hyperactivity of Cdk5 and reduced insulin secretion. Here, we set out to determine whether abnormal upregulation of Cdk5/p25 activity may be induced in a pancreatic beta cell line, Min6 cells. We first confirmed that p25 were induced in overexpressed p35 cells treated with HG and increased time course dependence. Next, we showed that no p25 was detected under short time HG stimulation (4-12 hrs), however was detectable in the long exposure in HG cells (24 hrs and 48 hrs). Cdk5 activity in the above cells was much higher than low glucose treated cells and resulted in more than 50% inhibition of insulin secretion. We confirmed these results by overexpression of p25 in Min6 cells. As in cortical neurons, CIP, a small peptide, inhibited Cdk5/p25 activity and restored insulin secretion. The same results were detected in co-infection of dominant negative Cdk5 (DNCdk5) with p25. CIP also reduced beta cells apoptosis induced by Cdk5/p25. These studies indicate that Cdk5/p25 hyperactivation deregulates insulin secretion and induces cell death in pancreatic beta cells and suggests that CIP may serve as a therapeutic agent for type 2 diabetes. PMID:24039692

  19. Direct visualisation of peptide hormones in cultured pancreatic islet alpha- and beta-cells by intact-cell mass spectrometry.

    PubMed

    Buchanan, Christina M; Malik, Arpita S; Cooper, Garth J S

    2007-01-01

    The application of intact-cell mass spectrometry (ICM) by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry to achieve direct protein-profiling of bacterial species is now well established. However, this methodology has not to our knowledge been applied to the analysis of mammalian cells in routine culture. Here, we describe a novel application of ICM by which we have identified proteins in intact cells from two lines representative of pancreatic islet alpha- and beta-cells. Adherent alphaTC1 clone 9 and betaTC6 F7 cells were harvested into phosphate-buffered saline (PBS) using enzyme-free dissociation buffer before 1 microL of cell suspension was spotted onto MALDI plates. Cells were overlaid with sinapinic acid then washed with pure water before application of a final coat of sinapinic acid. Data in the 2000-20,000 m/z range were acquired in linear mode on a Voyager DE-Pro mass spectrometer. The proteins which ionised were composed in large part of peptide hormones (e.g. insulin and glucagon) known to be packaged into the secretory granules of the beta- and alpha-cells respectively. However, in addition to visualising the peptides expected to be associated with these cells, a mass consistent with oxyntomodulin was identified in the cultured alpha-cells, a finding not previously reported to our knowledge. In summary, this paper describes, for the first time, a rapid and direct method useful for identifying secretory products in intact endocrine cells. PMID:17918213

  20. Insulin exerts metabolic and growth-promoting effects by a direct action on the liver in vivo: clarification of the functional significance of the portal vascular link between the beta cells of the pancreatic islets and the liver.

    PubMed Central

    Griffen, S C; Russell, S M; Katz, L S; Nicoll, C S

    1987-01-01

    The functional significance of the portal vascular link between the beta cells of the pancreatic islets and the liver has not been established. Previous studies indicated that insulin does not acutely regulate glucose metabolism by a direct hepatic effect. More recent observations suggest that the role of insulin in regulating body growth may be mediated, at least in part, by the liver. Our experiments were designed to test whether insulin can promote body growth and regulate glucose metabolism by a direct hepatic action in vivo. Rats were made diabetic by injections of streptozotocin, and insulin or solvent was infused into the jugular vein (JV) or the hepatic portal vein (HPV) for 14 days using catheters that were attached to osmotic minipumps. Infusion of a low dose of insulin (2 units per kg per day) into the JV had no effects on the hyperglycemia, body weight gain, tail growth, tibial epiphysial cartilage plate thickness, or serum levels of somatomedin C in the diabetic rats. However, the same dose given into the HPV caused a 30% reduction of blood glucose and stimulated a significant degree of growth, as determined by all indices. Infusion of a higher dose of insulin (5 units per kg per day) into either vein caused full restoration of body weight gain and tail growth and it restored the glycemic status almost to normal. However, it did not increase the tibial epiphysial plate width or serum somatomedin C levels above those of the rats given the low dose of the hormone into the HPV. These results indicate that insulin can act directly on the liver to promote body growth and to regulate glucose metabolism. The significance of direct delivery of insulin from the pancreatic beta cells to the liver may be as much for growth control as for glucose homeostasis. Images PMID:3313390

  1. Islet Stellate Cells Isolated from Fibrotic Islet of Goto-Kakizaki Rats Affect Biological Behavior of Beta-Cell.

    PubMed

    Li, Feng-Fei; Chen, Bi-Jun; Li, Wei; Li, Ling; Zha, Min; Zhou, S; Bachem, M G; Sun, Zi-Lin

    2016-01-01

    We previously isolated islet stellate cells (ISCs) from healthy Wistar rat islets. In the present study, we isolated "already primed by diabetic environment" ISCs from islets of Goto-Kakizaki rats, determined the gene profile of these cells, and assessed the effects of these ISCs on beta-cell function and survival. We detected gene expression of ISCs by digital gene expression. INS-1 cell proliferation, apoptosis, and insulin production were measured after being treated with ISCs supernatant (SN). We observed the similar expression pattern of ISCs and PSCs, but 1067 differentially expressed genes. Insulin production in INS-1 cells cultured with ISC-SN was significantly reduced. The 5-ethynyl-2'-deoxyuridine-positive INS-1 cells treated with ISC-SN were decreased. Propidium iodide- (PI-) positive INS-1 cells were 2.6-fold higher than those in control groups. Caspase-3 activity was increased. In conclusion, ISCs presented in fibrotic islet of GK rats might be special PSCs, which impaired beta-cell function and proliferation and increased beta-cell apoptosis. PMID:26697502

  2. Glucagon-like peptide-1 counteracts the detrimental effects of Advanced Glycation End-Products in the pancreatic beta cell line HIT-T 15

    SciTech Connect

    Puddu, A.; Storace, D.; Durante, A.; Odetti, P.; Viviani, G.L.

    2010-07-30

    Research highlights: {yields} GLP-1 prevents AGEs-induced cell death. {yields} GLP-1 prevents AGEs-induced oxidative stress. {yields} GLP-1 ameliorated AGEs-induced cell dysfunction. {yields} GLP-1 attenuates AGEs-induced RAGE increment. {yields} GLP-1 counteracts AGEs-induced pancreatic cell death and dysfunction. -- Abstract: Advanced Glycation End-Products (AGEs), a group of compounds resulting from the non-enzymatic reaction of reducing sugars with the free amino group of proteins, are implicated in diabetic complications. We previously demonstrated that exposure of the pancreatic islet cell line HIT-T 15 to high concentrations of AGEs significantly decreases cell proliferation and insulin secretion, and affects transcription factors regulating insulin gene transcription. The glucagon-like peptide-1 (GLP-1) is an incretin hormone that increases proinsulin biosynthesis, stimulates insulin secretion, and improves pancreatic beta-cell viability. The aim of this work was to investigate the effects of GLP-1 on the function and viability of HIT-T 15 cells cultured with AGEs. HIT-T 15 cells were cultured for 5 days in presence of AGEs alone, or supplemented with 10 nmol/l GLP-1. Cell viability, insulin secretion, redox balance, and expression of the AGEs receptor (RAGE) were then determined. The results showed that GLP-1 protected beta cell against AGEs-induced cell death preventing both apoptosis and necrosis. Moreover, addition of GLP-1 to the AGEs culture medium restored the redox balance, improved the responsiveness to glucose, and attenuated AGEs-induced RAGE expression. These findings provide evidence that GLP-1 protects beta cells from the dangerous effects of AGEs.

  3. To Be(ta Cell) or Not to Be(ta cell): New Mouse Models for Studying Gene Function in the Pancreatic β-Cell.

    PubMed

    Estall, Jennifer L; Screaton, Robert A

    2015-07-01

    A challenge in the pancreatic β-cell field has been to identify a promoter fragment that is active only in the β-cell compartment and inactive in other regions, such as the hypothalamic region of the brain. The presence of Cre recombinase alone in some models may also affect glucoregulation, confounding interpretation of gene function in the β-cell. A paper presented within describes the development and characterization of 2 new transgenic mice expressing Cre recombinase under the mouse insulin1 promoter that are useful for β-cell-specific gene ablation: the first is constitutive and coexpresses DsRed (Ins1-Cre-DsRed); the second allows β-cell-specific expression of the reverse tetracycline-controlled transactivator, which can be used for drug-dependent expression of a target gene of interest for overexpression studies. These novel models show robust specificity and efficiency and will be valuable tools for functional studies of gene action in β-cells, potentially alleviating current issues associated with previously available mouse lines. PMID:26091426

  4. O-Linked β-N-acetylglucosamine (O-GlcNAc) Acts as a Glucose Sensor to Epigenetically Regulate the Insulin Gene in Pancreatic Beta Cells.

    PubMed

    Durning, Sean P; Flanagan-Steet, Heather; Prasad, Nripesh; Wells, Lance

    2016-01-29

    The post-translational protein modification O-linked β-N-acetylglucosamine (O-GlcNAc) is a proposed nutrient sensor that has been shown to regulate multiple biological pathways. This dynamic and inducible enzymatic modification to intracellular proteins utilizes the end product of the nutrient sensing hexosamine biosynthetic pathway, UDP-GlcNAc, as its substrate donor. Type II diabetic patients have elevated O-GlcNAc-modified proteins within pancreatic beta cells due to chronic hyperglycemia-induced glucose overload, but a molecular role for O-GlcNAc within beta cells remains unclear. Using directed pharmacological approaches in the mouse insulinoma-6 (Min6) cell line, we demonstrate that elevating nuclear O-GlcNAc increases intracellular insulin levels and preserves glucose-stimulated insulin secretion during chronic hyperglycemia. The molecular mechanism for these observed changes appears to be, at least in part, due to elevated O-GlcNAc-dependent increases in Ins1 and Ins2 mRNA levels via elevations in histone H3 transcriptional activation marks. Furthermore, RNA deep sequencing reveals that this mechanism of altered gene transcription is restricted and that the majority of genes regulated by elevated O-GlcNAc levels are similarly regulated by a shift from euglycemic to hyperglycemic conditions. These findings implicate the O-GlcNAc modification as a potential mechanism for hyperglycemic-regulated gene expression in the beta cell. PMID:26598517

  5. Increased secretion of insulin and proliferation of islet {beta}-cells in rats with mesenteric lymph duct ligation

    SciTech Connect

    Nagino, Ko; Yokozawa, Junji; Sasaki, Yu; Matsuda, Akiko; Takeda, Hiroaki; Kawata, Sumio

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Insulin secretion was increased during the OGTT or IVGTT in mesenteric lymph duct-ligated rats. Black-Right-Pointing-Pointer Proliferation of islet {beta}-cells was upregulated in lymph duct-ligated rats. Black-Right-Pointing-Pointer Mesenteric lymph duct flow has a role in glucose metabolism. -- Abstract: Background and aims: It has been suggested that intestinal lymph flow plays an important role in insulin secretion and glucose metabolism after meals. In this study, we investigated the influence of ligation of the mesenteric lymph duct on glucose metabolism and islet {beta}-cells in rats. Methods: Male Sprague-Dawley rats (10 weeks old) were divided into two groups: one underwent ligation of the mesenteric lymph duct above the cistern (ligation group), and the other underwent a sham operation (sham group). After 1 and 2 weeks, fasting plasma concentrations of glucose, insulin, triglyceride, glucose-dependent insulinotropic polypeptide (GIP), and the active form of glucagon-like peptide-1 (GLP-1) were measured. At 2 weeks after the operation, the oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT) were performed. After the rats had been sacrificed, the insulin content of the pancreas was measured and the proliferation of {beta}-cells was assessed immunohistochemically using antibodies against insulin and Ki-67. Results: During the OGTT, the ligation group showed a significant decrease in the plasma glucose concentration at 120 min (p < 0.05) and a significant increase in the plasma insulin concentration by more than 2-fold at 15 min (p < 0.01). On the other hand, the plasma GIP concentration was significantly decreased at 60 min (p < 0.01) in the ligated group, while the active form of GLP-1 showed a significantly higher level at 90 min (1.7-fold; p < 0.05) and 120 min (2.5-fold; p < 0.01). During the IVGTT, the plasma insulin concentration in the ligation group was significantly higher at 2

  6. Delayed-rectifier (KV2.1) regulation of pancreatic beta-cell calcium responses to glucose: inhibitor specificity and modeling.

    PubMed

    Tamarina, Natalia A; Kuznetsov, Andrey; Fridlyand, Leonid E; Philipson, Louis H

    2005-10-01

    The delayed-rectifier (voltage-activated) K(+) conductance (K(V)) in pancreatic islet beta-cells has been proposed to regulate plasma membrane repolarization during responses to glucose, thereby determining bursting and Ca(2+) oscillations. Here, we verified the expression of K(V)2.1 channel protein in mouse and human islets of Langerhans. We then probed the function of K(V)2.1 channels in islet glucose responses by comparing the effect of hanatoxin (HaTx), a specific blocker of K(V)2.1 channels, with a nonspecific K(+) channel blocker, tetraethylammonium (TEA). Application of HaTx (1 microM) blocked delayed-rectifier currents in mouse beta-cells, resulting in a 40-mV rightward shift in threshold of activation of the voltage-dependent outward current. In the presence of HaTx, there was negligible voltage-activated outward current below 0 mV, suggesting that K(V)2.1 channels form the predominant part of this current in the physiologically relevant range. We then employed HaTx to study the role of K(V)2.1 in the beta-cell Ca(2+) responses to elevated glucose in comparison with TEA. Only HaTx was able to induce slow intracellular Ca(2+) concentration ([Ca(2+)](i)) oscillations in cells stimulated with 20 mM glucose, whereas TEA induced an immediate rise in [Ca(2+)](i) followed by rapid oscillations. In human islets, HaTx acted in a similar fashion. The data were analyzed using a detailed mathematical model of ionic flux and Ca(2+) regulation in beta-cells. The results can be explained by a specific HaTx effect on the K(V) current, whereas TEA affects multiple K(+) conductances. The results underscore the importance of K(V)2.1 channel in repolarization of the pancreatic beta-cell plasma membrane and its role in regulating insulin secretion. PMID:16014354

  7. Obestatin Accelerates the Recovery in the Course of Ischemia/Reperfusion-Induced Acute Pancreatitis in Rats

    PubMed Central

    Bukowczan, Jakub; Warzecha, Zygmunt; Ceranowicz, Piotr; Kuśnierz-Cabala, Beata; Tomaszewska, Romana

    2015-01-01

    Objective Several previous studies have shown that obestatin exhibits protective and regenerative effects in some organs including the stomach, kidney, and the brain. In the pancreas, pretreatment with obestatin inhibits the development of cerulein-induced acute pancreatitis, and promotes survival of pancreatic beta cells and human islets. However, no studies investigated the effect of obestatin administration following the onset of experimental acute pancreatitis. Aim The aim of this study was to evaluate the impact of obestatin therapy in the course of ischemia/reperfusion-induced pancreatitis. Moreover, we tested the influence of ischemia/reperfusion-induced acute pancreatitis and administration of obestatin on daily food intake and pancreatic exocrine secretion. Methods Acute pancreatitis was induced by pancreatic ischemia followed by reperfusion of the pancreas. Obestatin (8nmol/kg/dose) was administered intraperitoneally twice a day, starting 24 hours after the beginning of reperfusion. The effect of obestatin in the course of necrotizing pancreatitis was assessed between 2 and 14 days, and included histological, functional, and biochemical analyses. Secretory studies were performed on the third day after sham-operation or induction of acute pancreatitis in conscious rats equipped with chronic pancreatic fistula. Results Treatment with obestatin ameliorated morphological signs of pancreatic damage including edema, vacuolization of acinar cells, hemorrhages, acinar necrosis, and leukocyte infiltration of the gland, and led to earlier pancreatic regeneration. Structural changes were accompanied by biochemical and functional improvements manifested by accelerated normalization of interleukin-1β level and activity of myeloperoxidase and lipase, attenuation of the decrease in pancreatic DNA synthesis, and by an improvement of pancreatic blood flow. Induction of acute pancreatitis by pancreatic ischemia followed by reperfusion significantly decreased daily food

  8. The Rab-binding protein Noc2 is associated with insulin-containing secretory granules and is essential for pancreatic beta-cell exocytosis.

    PubMed

    Cheviet, Séverine; Coppola, Thierry; Haynes, Lee P; Burgoyne, Robert D; Regazzi, Romano

    2004-01-01

    The small GTPases Rab3 and Rab27 are associated with secretory granules of pancreatic beta-cells and regulate insulin exocytosis. In this study, we investigated the role of Noc2, a potential partner of these two GTPases, in insulin secretion. In the beta-cell line INS-1E wild-type Noc2, Noc265E, and Noc258A, a mutant capable of interacting with Rab27 but not Rab3, colocalized with insulin-containing vesicles. In contrast, two mutants (Noc2138S,141S and Noc2154A,155A,156A) that bind neither Rab3 nor Rab27 did not associate with secretory granules and were uniformly distributed throughout the cell cytoplasm. Overexpression of wild-type Noc2, Noc265E, or Noc258A inhibited hormone secretion elicited by insulin secretagogues. In contrast, overexpression of the mutants not targeted to secretory granules was without effect. Silencing of the Noc2 gene by RNA interference led to a strong impairment in the capacity of INS-1E cells to respond to insulin secretagogues, indicating that appropriate levels of Noc2 are essential for pancreatic beta-cell exocytosis. The defect was already detectable in the early secretory phase (0-10 min) but was particularly evident during the sustained release phase (10-45 min). Protein-protein binding studies revealed that Noc2 is a potential partner of Munc13, a component of the machinery that controls vesicle priming and insulin exocytosis. These data suggest that Noc2 is involved in the recruitment of secretory granules at the plasma membrane possibly via the interaction with Munc13. PMID:14593078

  9. Differentiation and transplantation of functional pancreatic beta cells generated from induced pluripotent stem cells derived from a type 1 diabetes mouse model.

    PubMed

    Jeon, Kilsoo; Lim, Hyejin; Kim, Jung-Hyun; Thuan, Nguyen Van; Park, Seung Hwa; Lim, Yu-Mi; Choi, Hye-Yeon; Lee, Eung-Ryoung; Kim, Jin-Hoi; Lee, Myung-Shik; Cho, Ssang-Goo

    2012-09-20

    The nonobese diabetic (NOD) mouse is a classical animal model for autoimmune type 1 diabetes (T1D), closely mimicking features of human T1D. Thus, the NOD mouse presents an opportunity to test the effectiveness of induced pluripotent stem cells (iPSCs) as a therapeutic modality for T1D. Here, we demonstrate a proof of concept for cellular therapy using NOD mouse-derived iPSCs (NOD-iPSCs). We generated iPSCs from NOD mouse embryonic fibroblasts or NOD mouse pancreas-derived epithelial cells (NPEs), and applied directed differentiation protocols to differentiate the NOD-iPSCs toward functional pancreatic beta cells. Finally, we investigated whether the NPE-iPSC-derived insulin-producing cells could normalize hyperglycemia in transplanted diabetic mice. The NOD-iPSCs showed typical embryonic stem cell-like characteristics such as expression of markers for pluripotency, in vitro differentiation, teratoma formation, and generation of chimeric mice. We developed a method for stepwise differentiation of NOD-iPSCs into insulin-producing cells, and found that NPE-iPSCs differentiate more readily into insulin-producing cells. The differentiated NPE-iPSCs expressed diverse pancreatic beta cell markers and released insulin in response to glucose and KCl stimulation. Transplantation of the differentiated NPE-iPSCs into diabetic mice resulted in kidney engraftment. The engrafted cells responded to glucose by secreting insulin, thereby normalizing blood glucose levels. We propose that NOD-iPSCs will provide a useful tool for investigating genetic susceptibility to autoimmune diseases and generating a cellular interaction model of T1D, paving the way for the potential application of patient-derived iPSCs in autologous beta cell transplantation for treating diabetes. PMID:22512788

  10. PED/PEA-15 Inhibits Hydrogen Peroxide-Induced Apoptosis in Ins-1E Pancreatic Beta-Cells via PLD-1

    PubMed Central

    Raciti, Gregory Alexander; Zatterale, Federica; Nigro, Cecilia; Mirra, Paola; Falco, Roberta; Ulianich, Luca; Di Jeso, Bruno; Formisano, Pietro; Miele, Claudia; Beguinot, Francesco

    2014-01-01

    The small scaffold protein PED/PEA-15 is involved in several different physiologic and pathologic processes, such as cell proliferation and survival, diabetes and cancer. PED/PEA-15 exerts an anti-apoptotic function due to its ability to interfere with both extrinsic and intrinsic apoptotic pathways in different cell types. Recent evidence shows that mice overexpressing PED/PEA-15 present larger pancreatic islets and increased beta-cells mass. In the present work we investigated PED/PEA-15 role in hydrogen peroxide-induced apoptosis in Ins-1E beta-cells. In pancreatic islets isolated from TgPED/PEA-15 mice hydrogen peroxide-induced DNA fragmentation was lower compared to WT islets. TUNEL analysis showed that PED/PEA-15 overexpression increases the viability of Ins-1E beta-cells and enhances their resistance to apoptosis induced by hydrogen peroxide exposure. The activity of caspase-3 and the cleavage of PARP-1 were markedly reduced in Ins-1E cells overexpressing PED/PEA-15 (Ins-1EPED/PEA-15). In parallel, we observed a decrease of the mRNA levels of pro-apoptotic genes Bcl-xS and Bad. In contrast, the expression of the anti-apoptotic gene Bcl-xL was enhanced. Accordingly, DNA fragmentation was higher in control cells compared to Ins-1EPED/PEA-15 cells. Interestingly, the preincubation with propranolol, an inhibitor of the pathway of PLD-1, a known interactor of PED/PEA-15, responsible for its deleterious effects on glucose tolerance, abolishes the antiapoptotic effects of PED/PEA-15 overexpression in Ins-1E beta-cells. The same results have been obtained by inhibiting PED/PEA-15 interaction with PLD-1 in Ins-1EPED/PEA-15. These results show that PED/PEA-15 overexpression is sufficient to block hydrogen peroxide-induced apoptosis in Ins-1E cells through a PLD-1 mediated mechanism. PMID:25489735

  11. The transcription factor C/EBP delta has anti-apoptotic and anti-inflammatory roles in pancreatic beta cells.

    PubMed

    Moore, Fabrice; Santin, Izortze; Nogueira, Tatiane C; Gurzov, Esteban N; Marselli, Lorella; Marchetti, Piero; Eizirik, Decio L

    2012-01-01

    In the course of Type 1 diabetes pro-inflammatory cytokines (e.g., IL-1β, IFN-γ and TNF-α) produced by islet-infiltrating immune cells modify expression of key gene networks in β-cells, leading to local inflammation and β-cell apoptosis. Most known cytokine-induced transcription factors have pro-apoptotic effects, and little is known regarding "protective" transcription factors. To this end, we presently evaluated the role of the transcription factor CCAAT/enhancer binding protein delta (C/EBPδ) on β-cell apoptosis and production of inflammatory mediators in the rat insulinoma INS-1E cells, in purified primary rat β-cells and in human islets. C/EBPδ is expressed and up-regulated in response to the cytokines IL-1β and IFN-γ in rat β-cells and human islets. Small interfering RNA-mediated C/EBPδ silencing exacerbated IL-1β+IFN-γ-induced caspase 9 and 3 cleavage and apoptosis in these cells. C/EBPδ deficiency increased the up-regulation of the transcription factor CHOP in response to cytokines, enhancing expression of the pro-apoptotic Bcl-2 family member BIM. Interfering with C/EBPδ and CHOP or C/EBPδ and BIM in double knockdown approaches abrogated the exacerbating effects of C/EBPδ deficiency on cytokine-induced β-cell apoptosis, while C/EBPδ overexpression inhibited BIM expression and partially protected β-cells against IL-1β+IFN-γ-induced apoptosis. Furthermore, C/EBPδ silencing boosted cytokine-induced production of the chemokines CXCL1, 9, 10 and CCL20 in β-cells by hampering IRF-1 up-regulation and increasing STAT1 activation in response to cytokines. These observations identify a novel function of C/EBPδ as a modulatory transcription factor that inhibits the pro-apoptotic and pro-inflammatory gene networks activated by cytokines in pancreatic β-cells. PMID:22347430

  12. The relationship between node degree and dissipation rate in networks of diffusively coupled oscillators and its significance for pancreatic beta cells

    NASA Astrophysics Data System (ADS)

    Gosak, Marko; Stožer, Andraž; Markovič, Rene; Dolenšek, Jurij; Marhl, Marko; Slak Rupnik, Marjan; Perc, Matjaž

    2015-07-01

    Self-sustained oscillatory dynamics is a motion along a stable limit cycle in the phase space, and it arises in a wide variety of mechanical, electrical, and biological systems. Typically, oscillations are due to a balance between energy dissipation and generation. Their stability depends on the properties of the attractor, in particular, its dissipative characteristics, which in turn determine the flexibility of a given dynamical system. In a network of oscillators, the coupling additionally contributes to the dissipation, and hence affects the robustness of the oscillatory solution. Here, we therefore investigate how a heterogeneous network structure affects the dissipation rate of individual oscillators. First, we show that in a network of diffusively coupled oscillators, the dissipation is a linearly decreasing function of the node degree, and we demonstrate this numerically by calculating the average divergence of coupled Hopf oscillators. Subsequently, we use recordings of intracellular calcium dynamics in pancreatic beta cells in mouse acute tissue slices and the corresponding functional connectivity networks for an experimental verification of the presented theory. We use methods of nonlinear time series analysis to reconstruct the phase space and calculate the sum of Lyapunov exponents. Our analysis reveals a clear tendency of cells with a higher degree, that is, more interconnected cells, having more negative values of divergence, thus confirming our theoretical predictions. We discuss these findings in the context of energetic aspects of signaling in beta cells and potential risks for pathological changes in the tissue.

  13. The relationship between node degree and dissipation rate in networks of diffusively coupled oscillators and its significance for pancreatic beta cells.

    PubMed

    Gosak, Marko; Stožer, Andraž; Markovič, Rene; Dolenšek, Jurij; Marhl, Marko; Rupnik, Marjan Slak; Perc, Matjaž

    2015-07-01

    Self-sustained oscillatory dynamics is a motion along a stable limit cycle in the phase space, and it arises in a wide variety of mechanical, electrical, and biological systems. Typically, oscillations are due to a balance between energy dissipation and generation. Their stability depends on the properties of the attractor, in particular, its dissipative characteristics, which in turn determine the flexibility of a given dynamical system. In a network of oscillators, the coupling additionally contributes to the dissipation, and hence affects the robustness of the oscillatory solution. Here, we therefore investigate how a heterogeneous network structure affects the dissipation rate of individual oscillators. First, we show that in a network of diffusively coupled oscillators, the dissipation is a linearly decreasing function of the node degree, and we demonstrate this numerically by calculating the average divergence of coupled Hopf oscillators. Subsequently, we use recordings of intracellular calcium dynamics in pancreatic beta cells in mouse acute tissue slices and the corresponding functional connectivity networks for an experimental verification of the presented theory. We use methods of nonlinear time series analysis to reconstruct the phase space and calculate the sum of Lyapunov exponents. Our analysis reveals a clear tendency of cells with a higher degree, that is, more interconnected cells, having more negative values of divergence, thus confirming our theoretical predictions. We discuss these findings in the context of energetic aspects of signaling in beta cells and potential risks for pathological changes in the tissue. PMID:26232966

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

    PubMed

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

    2015-10-01

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

  15. Combined Optical Coherence and Fluorescence Microscopy to assess dynamics and specificity of pancreatic beta-cell tracers

    PubMed Central

    Berclaz, Corinne; Pache, Christophe; Bouwens, Arno; Szlag, Daniel; Lopez, Antonio; Joosten, Lieke; Ekim, Selen; Brom, Maarten; Gotthardt, Martin; Grapin-Botton, Anne; Lasser, Theo

    2015-01-01

    The identification of a beta-cell tracer is a major quest in diabetes research. However, since MRI, PET and SPECT cannot resolve individual islets, optical techniques are required to assess the specificity of these tracers. We propose to combine Optical Coherence Microscopy (OCM) with fluorescence detection in a single optical platform to facilitate these initial screening steps from cell culture up to living rodents. OCM can image islets and vascularization without any labeling. Thereby, it alleviates the need of both genetically modified mice to detect islets and injection of external dye to reveal vascularization. We characterized Cy5.5-exendin-3, an agonist of glucagon-like peptide 1 receptor (GLP1R), for which other imaging modalities have been used and can serve as a reference. Cultured cells transfected with GLP1R and incubated with Cy5.5-exendin-3 show full tracer internalization. We determined that a dose of 1 μg of Cy5.5-exendin-3 is sufficient to optically detect in vivo the tracer in islets with a high specificity. In a next step, time-lapse OCM imaging was used to monitor the rapid and specific tracer accumulation in murine islets and its persistence over hours. This optical platform represents a versatile toolbox for selecting beta-cell specific markers for diabetes research and future clinical diagnosis. PMID:25988507

  16. Combined Optical Coherence and Fluorescence Microscopy to assess dynamics and specificity of pancreatic beta-cell tracers.

    PubMed

    Berclaz, Corinne; Pache, Christophe; Bouwens, Arno; Szlag, Daniel; Lopez, Antonio; Joosten, Lieke; Ekim, Selen; Brom, Maarten; Gotthardt, Martin; Grapin-Botton, Anne; Lasser, Theo

    2015-01-01

    The identification of a beta-cell tracer is a major quest in diabetes research. However, since MRI, PET and SPECT cannot resolve individual islets, optical techniques are required to assess the specificity of these tracers. We propose to combine Optical Coherence Microscopy (OCM) with fluorescence detection in a single optical platform to facilitate these initial screening steps from cell culture up to living rodents. OCM can image islets and vascularization without any labeling. Thereby, it alleviates the need of both genetically modified mice to detect islets and injection of external dye to reveal vascularization. We characterized Cy5.5-exendin-3, an agonist of glucagon-like peptide 1 receptor (GLP1R), for which other imaging modalities have been used and can serve as a reference. Cultured cells transfected with GLP1R and incubated with Cy5.5-exendin-3 show full tracer internalization. We determined that a dose of 1 μg of Cy5.5-exendin-3 is sufficient to optically detect in vivo the tracer in islets with a high specificity. In a next step, time-lapse OCM imaging was used to monitor the rapid and specific tracer accumulation in murine islets and its persistence over hours. This optical platform represents a versatile toolbox for selecting beta-cell specific markers for diabetes research and future clinical diagnosis. PMID:25988507

  17. Knowledge Gaps in Rodent Pancreas Biology: Taking Human Pluripotent Stem Cell-Derived Pancreatic Beta Cells into Our Own Hands

    PubMed Central

    Santosa, Munirah Mohamad; Low, Blaise Su Jun; Pek, Nicole Min Qian; Teo, Adrian Kee Keong

    2016-01-01

    In the field of stem cell biology and diabetes, we and others seek to derive mature and functional human pancreatic β cells for disease modeling and cell replacement therapy. Traditionally, knowledge gathered from rodents is extended to human pancreas developmental biology research involving human pluripotent stem cells (hPSCs). While much has been learnt from rodent pancreas biology in the early steps toward Pdx1+ pancreatic progenitors, much less is known about the transition toward Ngn3+ pancreatic endocrine progenitors. Essentially, the later steps of pancreatic β cell development and maturation remain elusive to date. As a result, the most recent advances in the stem cell and diabetes field have relied upon combinatorial testing of numerous growth factors and chemical compounds in an arbitrary trial-and-error fashion to derive mature and functional human pancreatic β cells from hPSCs. Although this hit-or-miss approach appears to have made some headway in maturing human pancreatic β cells in vitro, its underlying biology is vaguely understood. Therefore, in this mini-review, we discuss some of these late-stage signaling pathways that are involved in human pancreatic β cell differentiation and highlight our current understanding of their relevance in rodent pancreas biology. Our efforts here unravel several novel signaling pathways that can be further studied to shed light on unexplored aspects of rodent pancreas biology. New investigations into these signaling pathways are expected to advance our knowledge in human pancreas developmental biology and to aid in the translation of stem cell biology in the context of diabetes treatments. PMID:26834702

  18. Doc2b Serves as a Scaffolding Platform for Concurrent Binding of Multiple Munc18 Isoforms in Pancreatic Islet Beta Cells

    PubMed Central

    Ramalingam, Latha; Lu, Jingping; Hudmon, Andy; Thurmond, Debbie C.

    2015-01-01

    Biphasic glucose-stimulated insulin secretion (GSIS) from pancreatic beta cells involves SNARE protein-regulated exocytosis. SNARE complex assembly further requires the regulatory proteins Munc18c, Munc18-1 and Doc2b. Munc18-1 and Munc18c are required for 1st- and 2nd-phase GSIS, respectively. These distinct Munc18-1 and Munc18c roles are related to their transient high-affinity binding with their cognate t-SNAREs; Syntaxin 1A and Syntaxin 4, respectively. Doc2b is essential for both phases of GSIS, yet the molecular basis for this remains unresolved. Because Doc2b binds to Munc18-1 and Munc18c via it’s distinct C2A and C2B domains, respectively, we hypothesized that Doc2b may provide a plasma membrane-localized scaffold/platform for transient docking of these Munc18 isoforms during GSIS. Toward this, macromolecular complexes composed of Munc18c, Doc2b, and Munc18-1 were detected in beta cells. In vitro interaction assays indicated that Doc2b is required to bridge the interaction between Munc18c and Munc18-1 in the macromolecular complex; Munc18c and Munc18-1 failed to associate in the absence of Doc2b. Competition-based GST-Doc2b interaction assays revealed that Doc2b could simultaneously bind both Munc18-1 and Munc18c. Hence, these data support a working model wherein Doc2b functions as a docking platform/scaffold for transient interactions with the multiple Munc18 isoforms operative in insulin release, promoting SNARE assembly. PMID:25190515

  19. Cooperation between HMGA1, PDX-1, and MafA is Essential for Glucose-Induced Insulin Transcription in Pancreatic Beta Cells

    PubMed Central

    Arcidiacono, Biagio; Iiritano, Stefania; Chiefari, Eusebio; Brunetti, Francesco S.; Gu, Guoqiang; Foti, Daniela Patrizia; Brunetti, Antonio

    2014-01-01

    The high-mobility group AT-hook 1 (HMGA1) protein is a nuclear architectural factor that can organize chromatin structures. It regulates gene expression by controlling the formation of stereospecific multiprotein complexes called “enhanceosomes” on the AT-rich regions of target gene promoters. Previously, we reported that defects in HMGA1 caused decreased insulin receptor expression and increased susceptibility to type 2 diabetes mellitus in humans and mice. Interestingly, mice with disrupted HMGA1 gene had significantly smaller islets and decreased insulin content in their pancreata, suggesting that HMGA1 may have a direct role in insulin transcription and secretion. Herein, we investigate the regulatory roles of HMGA1 in insulin transcription. We provide evidence that HMGA1 physically interacts with PDX-1 and MafA, two critical transcription factors for insulin gene expression and beta-cell function, both in vitro and in vivo. We then show that the overexpression of HMGA1 significantly improves the transactivating activity of PDX-1 and MafA on human and mouse insulin promoters, while HMGA1 knockdown considerably decreased this transactivating activity. Lastly, we demonstrate that high glucose stimulus significantly increases the binding of HMGA1 to the insulin (INS) gene promoter, suggesting that HMGA1 may act as a glucose-sensitive element controlling the transcription of the INS gene. Together, our findings provide evidence that HMGA1, by regulating PDX-1- and MafA-induced transactivation of the INS gene promoter, plays a critical role in pancreatic beta-cell function and insulin production. PMID:25628604

  20. Down-regulation of zinc transporter 8 (SLC30A8) in pancreatic beta-cells promotes cell survival.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The pancreatic islet contains high levels of zinc in granular vesicles of ß-cells where insulin is matured, crystallized, and stored before secretion. Zinc is an essential co-factor for insulin crystallization forming dense cores in secretory granules. In insulin-containing secretory granules, zinc ...

  1. Maternal Obesity Accelerates Fetal Pancreatic Beta Cell but not Alpha Cell Development in the Sheep: Prenatal and Postnatal Consequences

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maternal obesity affects offspring weight, body composition and organ function, increasing diabetes and metabolic syndrome risk. We determined effects of maternal obesity and a high energy diet on fetal pancreatic development. Sixty days prior to breeding. ewes were assigned to control (C, 100% of N...

  2. Determinants of glucose toxicity and its reversibility in the pancreatic islet beta-cell line, HIT-T15.

    PubMed

    Gleason, C E; Gonzalez, M; Harmon, J S; Robertson, R P

    2000-11-01

    HIT-T15 cells, a clonal beta-cell line, were cultured and passaged weekly for 6 mo in RPMI 1640 media containing various concentrations of glucose. Insulin content decreased in the intermediate- and late-passage cells as a continuous rather than a threshold glucose concentration effect. In a second series of experiments, cells were grown in media containing either 0.8 or 16.0 mM glucose from passages 76 through 105. Subcultures of passages 86, 92, and 99 that had been grown in media containing 16.0 mM glucose were switched to media containing 0.8 mM glucose and also carried forward to passage 105. Dramatic increases in insulin content and secretion and insulin gene expression were observed when the switches were made at passages 86 and 92 but not when the switch was made at passage 99. These findings suggest that glucose toxicity of insulin-secreting cells is a continuous rather than a threshold function of glucose concentration and that the shorter the period of antecedent glucose toxicity, the more likely that full recovery of cell function will occur. PMID:11052953

  3. Pattern of rise in subplasma membrane Ca{sup 2+} concentration determines type of fusing insulin granules in pancreatic {beta} cells

    SciTech Connect

    Ohara-Imaizumi, Mica; Aoyagi, Kyota; Nakamichi, Yoko; Nishiwaki, Chiyono; Sakurai, Takashi; Nagamatsu, Shinya

    2009-07-31

    We simultaneously analyzed insulin granule fusion with insulin fused to green fluorescent protein and the subplasma membrane Ca{sup 2+} concentration ([Ca{sup 2+}]{sub PM}) with the Ca{sup 2+} indicator Fura Red in rat {beta} cells by dual-color total internal reflection fluorescence microscopy. We found that rapid and marked elevation in [Ca{sup 2+}]{sub PM} caused insulin granule fusion mostly from previously docked granules during the high KCl-evoked release and high glucose-evoked first phase release. In contrast, the slow and sustained elevation in [Ca{sup 2+}]{sub PM} induced fusion from newcomers translocated from the internal pool during the low KCl-evoked release and glucose-evoked second phase release. These data suggest that the pattern of the [Ca{sup 2+}]{sub PM} rise directly determines the types of fusing granules.

  4. Measurements of insulin responses as predictive markers of pancreatic beta-cell mass in normal and beta-cell-reduced lean and obese Göttingen minipigs in vivo.

    PubMed

    Larsen, Marianne O; Rolin, Bidda; Sturis, Jeppe; Wilken, Michael; Carr, Richard D; Pørksen, Niels; Gotfredsen, Carsten F

    2006-04-01

    At present, the best available estimators of beta-cell mass in humans are those based on measurement of insulin levels or appearance rates in the circulation. In several animal models, these estimators have been validated against beta-cell mass in lean animals. However, as many diabetic humans are obese, a correlation between in vivo tests and beta-cell mass must be evaluated over a range of body weights to include different levels of insulin sensitivity. For this purpose, obese (n = 10) and lean (n = 25) Göttingen minipigs were studied. Beta-cell mass had been reduced (n = 16 lean, n = 5 obese) with a combination of nicotinamide (67 mg/kg) and streptozotocin (125 mg/kg), acute insulin response (AIR) to intravenous glucose and/or arginine was tested, pulsatile insulin secretion was evaluated by deconvolution (n = 30), and beta-cell mass was determined histologically. AIR to 0.3 (r(2) = 0.4502, P < 0.0001) or 0.6 g/kg glucose (r(2) = 0.6806, P < 0.0001), 67 mg/kg arginine (r(2) = 0.5730, P < 0.001), and maximum insulin concentration (r(2) = 0.7726, P < 0.0001) were all correlated to beta-cell mass when evaluated across study groups, and regression lines were not different between lean and obese groups except for AIR to 0.3 g/kg glucose. Baseline pulse mass was not significantly correlated to beta-cell mass across the study groups (r(2) = 0.1036, NS), whereas entrained pulse mass did show a correlation across groups (r(2) = 0.4049, P < 0.001). This study supports the use of in vivo tests of insulin responses to evaluate beta-cell mass over a range of body weights in the minipig. Extensive stimulation of insulin secretion by a combination of glucose and arginine seems to give the best correlation to beta-cell mass. PMID:16278249

  5. Canine Fibroblast Growth Factor 21 Ameliorates Hyperglycemia Associated with Inhibiting Hepatic Gluconeogenesis and Improving Pancreatic Beta-Cell Survival in Diabetic Mice and Dogs

    PubMed Central

    Xu, Pengfei; Zhang, Yingjie; Jiang, Xinghao; Li, Junyan; Song, Liying; Khoso, Mir Hasson; Liu, Yunye; Wu, Qiang; Ren, Guiping; Li, Deshan

    2016-01-01

    Diabetes mellitus is a common endocrinopathy in dog. Fibroblast growth factor 21 (FGF-21) is a secreted protein, which is involved in glucose homeostasis. We speculate that the recombinant canine FGF-21 (cFGF-21) has the potential to become a powerful therapeutics to treat canine diabetes. The cFGF-21 gene was cloned and expressed in E. coli Rosetta (DE3). After purification, a cFGF-21 protein with the purity exceeding 95% was obtained. Mouse 3T3-L1 adipocytes and type 1 diabetic mice/dogs induced by STZ were used to examine the biological activity of cFGF-21 in vitro and in vivo, respectively. Results showed that cFGF-21 stimulated glucose uptake in adipocytes significantly in a dose-dependent manner, and reduced plasma glucose significantly in diabetic mice/dogs. After treatment with cFGF-21, the serum insulin level, glycosylated hemoglobin (HbA1c) level and the expressions of the hepatic gluconeogenesis genes (glucose-6-phosphatase, G6Pase and phosphoenolpyruvate carboxykinase, PCK) of the diabetic mice/dogs were attenuated significantly. In the mouse experiment, we also found that the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the expression of suppressor of cytokine signaling 3 (SOCS3) were up-regulated significantly in the livers after treatment. Histopathological and immunohistochemical results showed that treatment with cFGF-21 promoted recovery of pancreatic islets from STZ-induced apoptosis. Besides, we also found that treatment with cFGF-21 protected liver against STZ or hyperglycemia induced damage and the mechanism of this action associated with inhibiting oxidative stress. In conclusion, cFGF-21 represents a promising candidate for canine diabetes therapeutics. The mechanism of cFGF-21 ameliorates hyperglycemia associated with inhibiting hepatic gluconeogenesis by regulation of STAT3 signal pathway and improving pancreatic beta-cell survival. PMID:27203422

  6. Canine Fibroblast Growth Factor 21 Ameliorates Hyperglycemia Associated with Inhibiting Hepatic Gluconeogenesis and Improving Pancreatic Beta-Cell Survival in Diabetic Mice and Dogs.

    PubMed

    Xu, Pengfei; Zhang, Yingjie; Jiang, Xinghao; Li, Junyan; Song, Liying; Khoso, Mir Hasson; Liu, Yunye; Wu, Qiang; Ren, Guiping; Li, Deshan

    2016-01-01

    Diabetes mellitus is a common endocrinopathy in dog. Fibroblast growth factor 21 (FGF-21) is a secreted protein, which is involved in glucose homeostasis. We speculate that the recombinant canine FGF-21 (cFGF-21) has the potential to become a powerful therapeutics to treat canine diabetes. The cFGF-21 gene was cloned and expressed in E. coli Rosetta (DE3). After purification, a cFGF-21 protein with the purity exceeding 95% was obtained. Mouse 3T3-L1 adipocytes and type 1 diabetic mice/dogs induced by STZ were used to examine the biological activity of cFGF-21 in vitro and in vivo, respectively. Results showed that cFGF-21 stimulated glucose uptake in adipocytes significantly in a dose-dependent manner, and reduced plasma glucose significantly in diabetic mice/dogs. After treatment with cFGF-21, the serum insulin level, glycosylated hemoglobin (HbA1c) level and the expressions of the hepatic gluconeogenesis genes (glucose-6-phosphatase, G6Pase and phosphoenolpyruvate carboxykinase, PCK) of the diabetic mice/dogs were attenuated significantly. In the mouse experiment, we also found that the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the expression of suppressor of cytokine signaling 3 (SOCS3) were up-regulated significantly in the livers after treatment. Histopathological and immunohistochemical results showed that treatment with cFGF-21 promoted recovery of pancreatic islets from STZ-induced apoptosis. Besides, we also found that treatment with cFGF-21 protected liver against STZ or hyperglycemia induced damage and the mechanism of this action associated with inhibiting oxidative stress. In conclusion, cFGF-21 represents a promising candidate for canine diabetes therapeutics. The mechanism of cFGF-21 ameliorates hyperglycemia associated with inhibiting hepatic gluconeogenesis by regulation of STAT3 signal pathway and improving pancreatic beta-cell survival. PMID:27203422

  7. Low dose monoethyl phthalate (MEP) exposure triggers proliferation by activating PDX-1 at 1.1B4 human pancreatic beta cells.

    PubMed

    Güven, Celal; Dal, Fulya; Aydoğan Ahbab, Müfide; Taskin, Eylem; Ahbab, Süleyman; Adin Çinar, Suzan; Sırma Ekmekçi, Sema; Güleç, Çağrı; Abacı, Neslihan; Akçakaya, Handan

    2016-07-01

    Phthalate plasticizers used in a wide range of common plastic products are released into the environment and may pose a risk of increased incidence of type 2 diabetes. In this work, we studied the effects of monoethyl phthalate (MEP), the metabolite of diethyl phthalate, exposure on 1.1B4 human pancreatic beta cells at low doses (1-1000 nM). We showed that MEP treatment induced proliferation in 1.1B4 cells. Also PCNA protein expression levels were increased related to proliferation induction. It has been noted that phthalates can exert estrogen mediated response by interacting with ER. In our study 24 h MEP treatment decreased ERα protein expression level conversely it increased the same protein expression level after 72 h treatment. Also MEP treatment decreased ERβ expression after 72 h at 1.1B4 cells. Our results further show that insulin content of 1.1B4 cells were increased with low dose MEP treatment. Along with our insulin content results, PDX- 1 expression levels were also increased at 1.1B4 cells with MEP treatment. These findings suggest that MEP acts as an estrogenic compound and PPARγ agonist at lower concentrations. Also it should be noted that PDX-1 may be a critical regulator of 1.1B4 cells treated with MEP. PMID:27133914

  8. Role of antioxidant enzymes and antioxidant compound probucol in antiradical protection of pancreatic beta-cells during alloxan-induced diabetes.

    PubMed

    Lankin, V Z; Korchin, V I; Konovalova, G G; Lisina, M O; Tikhaze, A K; Akmaev, I G

    2004-01-01

    The severity of disturbances in carbohydrate metabolism in rats with alloxan-induced diabetes depended on activity of antioxidant enzymes in the target organ (pancreas). Damage to the pancreas is related to intensive generation of reactive oxygen species, free radicals, and lipid peroxides. Alloxan-induced diabetes in rats is a free radical disease, which in vivo serves as a useful model for the search for pharmacological preparations with antiradical and antioxidant properties. The antioxidant compound probucol indirectly increased activity of antioxidant enzymes in the pancreas and prevented the development of alloxan-induced diabetes in rats. Our results indicate that different sensitivity of laboratory animals of various species (rats and guinea pigs) to the influence of alloxan is associated with abnormal variations in activity of enzymes utilizing reactive oxygen species and lipid peroxides in mammalian pancreatic cells. PMID:15085236

  9. Involvement of a mitochondrial phosphatase in the regulation of ATP production and insulin secretion in pancreatic beta cells.

    PubMed

    Pagliarini, David J; Wiley, Sandra E; Kimple, Michelle E; Dixon, Jesse R; Kelly, Patrick; Worby, Carolyn A; Casey, Patrick J; Dixon, Jack E

    2005-07-22

    Reversible phosphorylation is the cell's most prevalent form of posttranslational modification, yet its role in the regulation of mitochondrial functions is poorly understood. We have discovered that a member of the dual-specific protein tyrosine phosphatase (DS-PTP) family, PTPMT1 (PTP localized to the Mitochondrion 1) resides nearly exclusively in mitochondria. PTPMT1 is targeted to the mitochondrion by an N-terminal signal sequence and is found anchored to the matrix face of the inner membrane. Knockdown of PTPMT1 expression in the pancreatic insulinoma cell line INS-1 832/13 alters the mitochondrial phosphoprotein profile and markedly enhances both ATP production and insulin secretion. These data define PTPMT1 as a potential drug target for the treatment of type II diabetes and strengthen the notion that mitochondria are an underappreciated site of signaling by reversible phosphorylation. PMID:16039589

  10. Synthesis and evaluation of [18F]Exendin (9-39) as a potential biomarker to measure pancreatic beta-cell mass

    PubMed Central

    Wang, Yi; Lim, Keunpoong; Normandin, Marc; Zhao, Xiaojian; Cline, Gary W.; Ding, Yu-Shin

    2015-01-01

    Introduction Glucagon-like peptide 1 (GLP-1) is released in response to food intake and plays an important role in maintaining blood glucose homeostasis. Exendin (9-39), a potent GLP-1R antagonist, has been labeled with In-111 for SPECT imaging. We report here the first radiosynthesis of [18F]exendin (9-39) ([18F]Ex(9-39)) and an evaluation of its potential as a biomarker for in vivo PET imaging of pancreatic β-cell mass (BCM) in rats. Methods F-18 label was introduced by conjugation of [18F]4-fluorobenzaldehyde with an Ex(9-39) derivative containing a 6-hydrazinonicotinyl group on the -amine of Lys27. PET imaging was carried out in Sprague-Dawley rats (5 control, 5 streptozotocin-induced diabetic) and BioBreeding-Diabetes Prone rats (3 at 7 wks, 3 at 12 wks) using HRRT following 0.187±0.084 mCi [18F]Ex(9-39) administration. Time activity curves were obtained from pancreas, liver and kidney. Pancreases were assayed for insulin content after the imaging study. Results Site-specifically labeled [18F]Ex(9-39) was purified on a G15 open column with radiochemical and chemical purities >98%. PET imaging showed pancreatic SUV peaked at 10 min, and plateaued by 50 min to the end of scan (240 min). No correlations of pancreatic SUV with post-mortem measures of insulin content were seen. Conclusions [18F]Ex(9-39) was successfully prepared and used for PET imaging for the first time to measure pancreatic BCM. The results suggest that derivatization of the Lys27 residue might reduce binding affinity, as evidenced by the absence of specific binding. Exendin analogs radiolabeled at other sites may elucidate the active site required for binding. PMID:22033026

  11. Antibody Response to Serpin B13 Induces Adaptive Changes in Mouse Pancreatic Islets and Slows Down the Decline in the Residual Beta Cell Function in Children with Recent Onset of Type 1 Diabetes Mellitus.

    PubMed

    Kryvalap, Yury; Lo, Chi-Wen; Manuylova, Ekaterina; Baldzizhar, Raman; Jospe, Nicholas; Czyzyk, Jan

    2016-01-01

    Type 1 diabetes mellitus (T1D) is characterized by a heightened antibody (Ab) response to pancreatic islet self-antigens, which is a biomarker of progressive islet pathology. We recently identified a novel antibody to clade B serpin that reduces islet-associated T cell accumulation and is linked to the delayed onset of T1D. As natural immunity to clade B arises early in life, we hypothesized that it may influence islet development during that time. To test this possibility healthy young Balb/c male mice were injected with serpin B13 mAb or IgG control and examined for the number and cellularity of pancreatic islets by immunofluorescence and FACS. Beta cell proliferation was assessed by measuring nucleotide analog 5-ethynyl-2'-deoxyuridine (5-EdU) incorporation into the DNA and islet Reg gene expression was measured by real time PCR. Human studies involved measuring anti-serpin B13 autoantibodies by Luminex. We found that injecting anti-serpin B13 monoclonal Ab enhanced beta cell proliferation and Reg gene expression, induced the generation of ∼80 pancreatic islets per animal, and ultimately led to increase in the beta cell mass. These findings are relevant to human T1D because our analysis of subjects just diagnosed with T1D revealed an association between baseline anti-serpin activity and slower residual beta cell function decline in the first year after the onset of diabetes. Our findings reveal a new role for the anti-serpin immunological response in promoting adaptive changes in the endocrine pancreas and suggests that enhancement of this response could potentially help impede the progression of T1D in humans. PMID:26578518

  12. Measurement of the Absolute Magnitude and Time Courses of Mitochondrial Membrane Potential in Primary and Clonal Pancreatic Beta-Cells

    PubMed Central

    Gerencser, Akos A.; Mookerjee, Shona A.; Jastroch, Martin; Brand, Martin D.

    2016-01-01

    The aim of this study was to simplify, improve and validate quantitative measurement of the mitochondrial membrane potential (ΔψM) in pancreatic β-cells. This built on our previously introduced calculation of the absolute magnitude of ΔψM in intact cells, using time-lapse imaging of the non-quench mode fluorescence of tetramethylrhodamine methyl ester and a bis-oxonol plasma membrane potential (ΔψP) indicator. ΔψM is a central mediator of glucose-stimulated insulin secretion in pancreatic β-cells. ΔψM is at the crossroads of cellular energy production and demand, therefore precise assay of its magnitude is a valuable tool to study how these processes interplay in insulin secretion. Dispersed islet cell cultures allowed cell type-specific, single-cell observations of cell-to-cell heterogeneity of ΔψM and ΔψP. Glucose addition caused hyperpolarization of ΔψM and depolarization of ΔψP. The hyperpolarization was a monophasic step increase, even in cells where the ΔψP depolarization was biphasic. The biphasic response of ΔψP was associated with a larger hyperpolarization of ΔψM than the monophasic response. Analysis of the relationships between ΔψP and ΔψM revealed that primary dispersed β-cells responded to glucose heterogeneously, driven by variable activation of energy metabolism. Sensitivity analysis of the calibration was consistent with β-cells having substantial cell-to-cell variations in amounts of mitochondria, and this was predicted not to impair the accuracy of determinations of relative changes in ΔψM and ΔψP. Finally, we demonstrate a significant problem with using an alternative ΔψM probe, rhodamine 123. In glucose-stimulated and oligomycin-inhibited β-cells the principles of the rhodamine 123 assay were breached, resulting in misleading conclusions. PMID:27404273

  13. Measurement of the Absolute Magnitude and Time Courses of Mitochondrial Membrane Potential in Primary and Clonal Pancreatic Beta-Cells.

    PubMed

    Gerencser, Akos A; Mookerjee, Shona A; Jastroch, Martin; Brand, Martin D

    2016-01-01

    The aim of this study was to simplify, improve and validate quantitative measurement of the mitochondrial membrane potential (ΔψM) in pancreatic β-cells. This built on our previously introduced calculation of the absolute magnitude of ΔψM in intact cells, using time-lapse imaging of the non-quench mode fluorescence of tetramethylrhodamine methyl ester and a bis-oxonol plasma membrane potential (ΔψP) indicator. ΔψM is a central mediator of glucose-stimulated insulin secretion in pancreatic β-cells. ΔψM is at the crossroads of cellular energy production and demand, therefore precise assay of its magnitude is a valuable tool to study how these processes interplay in insulin secretion. Dispersed islet cell cultures allowed cell type-specific, single-cell observations of cell-to-cell heterogeneity of ΔψM and ΔψP. Glucose addition caused hyperpolarization of ΔψM and depolarization of ΔψP. The hyperpolarization was a monophasic step increase, even in cells where the ΔψP depolarization was biphasic. The biphasic response of ΔψP was associated with a larger hyperpolarization of ΔψM than the monophasic response. Analysis of the relationships between ΔψP and ΔψM revealed that primary dispersed β-cells responded to glucose heterogeneously, driven by variable activation of energy metabolism. Sensitivity analysis of the calibration was consistent with β-cells having substantial cell-to-cell variations in amounts of mitochondria, and this was predicted not to impair the accuracy of determinations of relative changes in ΔψM and ΔψP. Finally, we demonstrate a significant problem with using an alternative ΔψM probe, rhodamine 123. In glucose-stimulated and oligomycin-inhibited β-cells the principles of the rhodamine 123 assay were breached, resulting in misleading conclusions. PMID:27404273

  14. Stevioside counteracts the glyburide-induced desensitization of the pancreatic beta-cell function in mice: studies in vitro.

    PubMed

    Chen, Jianguo; Jeppesen, Per Bendix; Nordentoft, Iver; Hermansen, Kjeld

    2006-12-01

    The sulfonylurea glyburide (GB) is one of the most frequently used drugs in diabetes treatment. Long-term pretreatment with GB causes elevated basal insulin secretion (BIS) and decreased glucose-stimulated insulin secretion (GSIS). These characteristics may play an important role for the development of hypoglycemia and secondary failure. Stevioside (SVS), a substance extracted from leaves of Stevia rebaudiana Bertoni, enhances GSIS but not BIS. The aim of the present study was to clarify whether 24-hour exposure of isolated mouse islets to GB causes dose-dependent decrease in the GSIS and whether it is possible to counteract this desensitization by SVS. We also tested the impact of the incretin glucagon-like peptide-1 (GLP-1) on the GB-induced desensitization. After 24-hour preincubation with GB in combination with SVS or GLP-1, we measured the basal and glucose-stimulated insulin responses and the total islet insulin content. We also determined the fold change in gene expression of pancreatic and duodenal homeobox 1 and glucose transporter isoform 2. After 24-hour preincubation in 11.1 mmol/L glucose, GB (10(-11)-10(-3) mol/L) caused a dose-dependent decrease in GSIS (16.7 mmol/L glucose) (P < .001). GB (10(-7) mol/L) pretreatment elevated BIS, but neither SVS (10(-7) mol/L) nor GLP-1 (10(-7) mol/L) could reverse this. Interestingly, the GB-induced desensitization of GSIS was counteracted by both SVS (P < .05) and GLP-1 (P < .05). SVS reversed the decrease in insulin content caused by GB pretreatment (P < .05). GB pretreatment did not change gene expression of pancreatic and duodenal homeobox 1 nor glucose transporter isoform 2, whereas SVS significantly up-regulated the expression of both genes by more than 2-fold (P < .05). Our results showed that SVS in combination with GB did not reverse GB-induced increase in BIS, whereas both SVS and GLP-1 counteracted GB-induced desensitization of GSIS. SVS is able to counteract the desensitizing effects of GB and may be a

  15. KAT2B Is Required for Pancreatic Beta Cell Adaptation to Metabolic Stress by Controlling the Unfolded Protein Response.

    PubMed

    Rabhi, Nabil; Denechaud, Pierre-Damien; Gromada, Xavier; Hannou, Sarah Anissa; Zhang, Hongbo; Rashid, Talha; Salas, Elisabet; Durand, Emmanuelle; Sand, Olivier; Bonnefond, Amélie; Yengo, Loic; Chavey, Carine; Bonner, Caroline; Kerr-Conte, Julie; Abderrahmani, Amar; Auwerx, Johan; Fajas, Lluis; Froguel, Philippe; Annicotte, Jean-Sébastien

    2016-05-01

    The endoplasmic reticulum (ER) unfolded protein response (UPR(er)) pathway plays an important role in helping pancreatic β cells to adapt their cellular responses to environmental cues and metabolic stress. Although altered UPR(er) gene expression appears in rodent and human type 2 diabetic (T2D) islets, the underlying molecular mechanisms remain unknown. We show here that germline and β cell-specific disruption of the lysine acetyltransferase 2B (Kat2b) gene in mice leads to impaired insulin secretion and glucose intolerance. Genome-wide analysis of Kat2b-regulated genes and functional assays reveal a critical role for Kat2b in maintaining UPR(er) gene expression and subsequent β cell function. Importantly, Kat2b expression is decreased in mouse and human diabetic β cells and correlates with UPR(er) gene expression in normal human islets. In conclusion, Kat2b is a crucial transcriptional regulator for adaptive β cell function during metabolic stress by controlling UPR(er) and represents a promising target for T2D prevention and treatment. PMID:27117420

  16. Pharmacological attenuation of chronic alcoholic pancreatitis induced hypersensitivity in rats

    PubMed Central

    McIlwrath, Sabrina L; Westlund, Karin N

    2015-01-01

    AIM: To characterize an alcohol and high fat diet induced chronic pancreatitis rat model that mimics poor human dietary choices. METHODS: Experimental rats were fed a modified Lieber-DeCarli alcohol (6%) and high-fat (65%) diet (AHF) for 10 wk while control animals received a regular rodent chow diet. Weekly behavioral tests determined mechanical and heat sensitivity. In week 10 a fasting glucose tolerance test was performed, measuring blood glucose levels before and after a 2 g/kg bodyweight intraperitoneal (i.p.) injection of glucose. Post mortem histological analysis was performed by staining pancreas and liver tissue sections with hematoxylin and eosin. Pancreas sections were also stained with Sirius red and fast green to quantify collagen content. Insulin-expressing cells were identified immunohistochemically in separate sections. Tissue staining density was quantified using Image J software. After mechanical and heat sensitivity became stable (weeks 6-10) in the AHF-fed animals, three different drugs were tested for their efficacy in attenuating pancreatitis associated hypersensitivity: a Group II metabotropic glutamate receptor specific agonist (2R,4R)-4-Aminopyrrolidine-2,4-dicarboxylate (APDC, 3 mg/kg, ip; Tocris, Bristol, United Kingdom), nociceptin (20, 60, 200 nmol/kg, ip; Tocris), and morphine sulfate (3 mg/kg, μ-opioid receptor agonist; Baxter Healthcare, Deerfield, IL, United States). RESULTS: Histological analysis of pancreas and liver determined that unlike control rats, AHF fed animals had pancreatic fibrosis, acinar and beta cell atrophy, with steatosis in both organs. Fat vacuolization was significantly increased in AHF fed rats (6.4% ± 1.1% in controls vs 23.8% ± 4.2%, P < 0.05). Rats fed the AHF diet had reduced fasting glucose tolerance in week 10 when peak blood glucose levels reached significantly higher concentrations than controls (127.4 ± 9.2 mg/dL in controls vs 161.0 ± 8.6 mg/dL, P < 0.05). This concurred with a 3.5 fold higher

  17. On the origin of the beta cell.

    PubMed

    Oliver-Krasinski, Jennifer M; Stoffers, Doris A

    2008-08-01

    The major forms of diabetes are characterized by pancreatic islet beta-cell dysfunction and decreased beta-cell numbers, raising hope for cell replacement therapy. Although human islet transplantation is a cell-based therapy under clinical investigation for the treatment of type 1 diabetes, the limited availability of human cadaveric islets for transplantation will preclude its widespread therapeutic application. The result has been an intense focus on the development of alternate sources of beta cells, such as through the guided differentiation of stem or precursor cell populations or the transdifferentiation of more plentiful mature cell populations. Realizing the potential for cell-based therapies, however, requires a thorough understanding of pancreas development and beta-cell formation. Pancreas development is coordinated by a complex interplay of signaling pathways and transcription factors that determine early pancreatic specification as well as the later differentiation of exocrine and endocrine lineages. This review describes the current knowledge of these factors as they relate specifically to the emergence of endocrine beta cells from pancreatic endoderm. Current therapeutic efforts to generate insulin-producing beta-like cells from embryonic stem cells have already capitalized on recent advances in our understanding of the embryonic signals and transcription factors that dictate lineage specification and will most certainly be further enhanced by a continuing emphasis on the identification of novel factors and regulatory relationships. PMID:18676806

  18. Closing in on Mass Production of Mature Human Beta Cells.

    PubMed

    Kieffer, Timothy J

    2016-06-01

    Human pluripotent stem cell differentiation protocols based on mimicking developmental pathways are getting close to generating fully fledged pancreatic endocrine cells, including insulin-producing beta cells. However, challenges remain in identifying pathways to trigger the attainment of robust glucose responsiveness that occurs postnatally in beta cells. PMID:27257758

  19. TRPV6 channel modulates proliferation of insulin secreting INS-1E beta cell line.

    PubMed

    Skrzypski, M; Khajavi, N; Mergler, S; Szczepankiewicz, D; Kołodziejski, P A; Metzke, D; Wojciechowicz, T; Billert, M; Nowak, K W; Strowski, M Z

    2015-12-01

    Transient receptor potential channel vanilloid type 6 (TRPV6) is a non-selective cation channel with high permeability for Ca²⁺ ions. So far, the role of TRPV6 in pancreatic beta cells is unknown. In the present study, we characterized the role of TRPV6 in controlling calcium signaling, cell proliferation as well as insulin expression, and secretion in experimental INS-1E beta cell model. TRPV6 protein production was downregulated using siRNA by approx. 70%, as detected by Western blot. Intracellular free Ca²⁺ ([Ca²⁺]i) was measured by fluorescence Ca²⁺ imaging using fura-2. Calcineurin/NFAT signaling was analyzed using a NFAT reporter assay as well as a calcineurin activity assay. TRPV6 downregulation resulted in impaired cellular calcium influx. Its downregulation also reduced cell proliferation and decreased insulin mRNA expression. These changes were companied by the inhibition of the calcineurin/NFAT signaling. In contrast, insulin exocytosis was not affected by TRPV6 downregulation. In conclusion, this study demonstrates for the first time the expression of TRPV6 in INS-1E cells and rat pancreatic beta cells and describes its role in modulating calcium signaling, beta cell proliferation and insulin mRNA expression. In contrast, TRPV6 fails to influence insulin secretion. PMID:26384871

  20. Gabapentin-induced mitogenic activity in rat pancreatic acinar cells.

    PubMed

    Dethloff, L; Barr, B; Bestervelt, L; Bulera, S; Sigler, R; LaGattuta, M; de La Iglesia, F

    2000-05-01

    Gabapentin induces pancreatic acinar cell tumors in rats through unknown, yet apparently nongenotoxic mechanisms. The primary objective of this study was to determine whether gabapentin acts as a tumor promoter by stimulating acinar cell proliferation in rat pancreas. To this end, indices of pancreatic growth, including increased pancreatic weight, stimulation of acinar cell proliferation, and/or enhanced expression of immediate-early oncogenes were monitored in rats given gabapentin in the diet at 2 g/kg/day for up to 12 months. Rats fed raw soy flour (RSF), a known inducer of pancreatic acinar cell tumors through cholecystokinin-mediated mitogenic stimulation, were used throughout as positive controls. In addition, recent data suggests that gabapentin binds to the alpha(2)delta subunit of a voltage-gated, L-type calcium channel. Because signaling pathways for proliferative processes in pancreatic acinar cells involve intracellular calcium mobilization, the effects of gabapentin on intracellular calcium mobilization ([Ca(2+)](i)) and (3)H-thymidine incorporation were investigated in pancreatic acinar cells isolated from normal rat pancreas and in the AR42J rat pancreatic tumor cell line. As indicated by BrdU labeling indices, acinar cell proliferation increased 3-fold by Day 3 of RSF treatment and remained slightly greater than controls throughout the experiment. Pancreatic weights of RSF-fed rats were 32 to 56% greater than controls throughout the experiment. In contrast, gabapentin had no effect on pancreatic weight or acinar cell labeling index, and therefore had no apparent effect on pancreatic growth. In isolated pancreatic acinar cells, however, gabapentin induced mobilization of intracellular calcium and caused a slight increase in (3)H-thymidine incorporation. The data suggest that gabapentin may possess low level mitogenic activity, which is not easily detectable in in vivo assays. PMID:10788559

  1. A stereological study of effects of aqueous extract of Tamarindus indica seeds on pancreatic islets in streptozotocin-induced diabetic rats.

    PubMed

    Hamidreza, Hamidreza; Heidari, Zahra; Shahraki, Mohammadreza; Moudi, Bita

    2010-10-01

    Tamarindus indica Linn was used as a traditional medicine for the management of diabetes mellitus in human and experimental animals. This study investigated effects of aqueous extract of Tamarindus indica seeds (AETIS) against STZ-induced damages in pancreatic islands by means of stereological methods. sixty matured normoglycemic male Wistar rats, weighing 200-250 gr, were selected and randomly divided into 6 groups (n=10). Control, STZ-induced diabetic; by intraperitoneal injection of 55 mg/Kg streptozotocin, Treated control group (TC); received AETIS at a dose of 200mg/kg/day, and AETIS treated diabetic groups (TD1-3); received respectively AETIS at the dose of 50, 100,and 200 mg/kg/day by gavage from one week after induction of diabetes by STZ. After 8 weeks of experiment, stereological estimation of volume density and total volume of islets and beta cells, volume weighted mean islets volume, mass of beta cells, islets, and pancreas and total number of islets were done. Volume density and total volume of islets, volume weighted mean islets volume, volume density islets/pancreas, volume density beta cells/islet, mass of islets and pancreas of treated diabetic groups (TD1-3) were significantly higher than untreated diabetic group (P<0.001), and in TD3 group these values were comparable to controls. Although total volume and mass of beta cells in TD1-3 were significantly higher than D group but they were significantly lower than control group (P>0.05). Total number of islets, pancreas wet weight and volume did not show any significant changes between control and experimental groups (P>0.05). Results suggested that AETIS partially restores pancreatic beta cells and repairs STZ-induced damages in rats. PMID:20884458

  2. Evidence that down-regulation of. beta. -cell glucose transporters in non-insulin-dependent diabetes may be the cause of diabetic hyperglycemia

    SciTech Connect

    Orci, L.; Ravazzola, M.; Baetens, D.; Amherdt, M. ); Inman, L.; Johnson, J.H.; Unger, R.H. Dept. of Veterans Affairs Medical Center, Dallas, TX ); Peterson, R.G. ); Newgard, C.B. )

    1990-12-01

    Non-insulin-dependent diabetes mellitus (NIDDM) is attributed to a failure of pancreatic {beta} cells to maintain insulin secretion at a level sufficient to compensate for underlying insulin resistance. In the ZDF rat, a model of NIDDM that closely resembles the human syndrome, the authors have previously reported profound underexpression of GLUT-2, the high-K{sub m} facilitative glucose transporter expressed by {beta} cells of normal animals. Here they report that islets of diabetic rats exhibit a marked decrease in the volume density of GLUT-2-positive {beta} cells and a reduction at the electron-microscopic level in the number of GLUT-2-immunoreactive sites per unit of {beta}-cell plasma membrane. The deficiency of GLUT-2 cannot be induced in normal {beta} cells by in vivo or in vitro exposure to high levels of glucose nor can it be prevented in {beta} cells of prediabetic ZDF rats by elimination of hyperglycemia. They conclude that this dearth of immunodetectable GLUT-2 in NIDDM is not secondary to hyperglycemia and therefore that it may well play a causal role in the development of hyperglycemia.

  3. In vivo regeneration of insulin-producing beta-cells.

    PubMed

    Jun, Hee-Sook

    2010-01-01

    Type 1 and type 2 diabetes mellitus are considered to be caused by defective control of blood glucose resulting from a reduced beta-cell mass. Thus, the restoration of a functional beta-cell mass by replacing the damaged beta-cells or stimulating beta-cell regeneration is a logical approach for the treatment of diabetes. Strategies for increasing the beta-cell mass include stimulating beta-cell replication and differentiation and inhibiting beta-cell death. Treatment with various growth factors such as GLP-1, BTC, HGF, and EGF and forced expression of beta-cell transcription factors such as Pdx-1, NeuroD, and MafA resulted in the regeneration of beta-cells in vivo. Another approach is the administration of stem/progenitor cells, which can differentiate into insulin-producing cells. However, there are no satisfactory methods yet for clinical application. Understanding the mechanisms of the regenerative process of pancreatic beta-cells will pave the way for the development of regenerative medicine for treatment of diabetes. PMID:20217517

  4. Emodin promoted pancreatic claudin-5 and occludin expression in experimental acute pancreatitis rats

    PubMed Central

    Xia, Xian-Ming; Li, Bang-Ku; Xing, Shi-Mei; Ruan, Hai-Ling

    2012-01-01

    AIM: To investigate the effect of emodin on pancreatic claudin-5 and occludin expression, and pancreatic paracellular permeability in acute pancreatitis (AP). METHODS: Experimental pancreatitis was induced by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. Emodin was injected via the external jugular vein 0 or 6 h after induction of AP. Rats from sham operation and AP groups were injected with normal saline at the same time. Samples of pancreas were obtained 6 or 12 h after drug administration. Pancreatic morphology was examined with hematoxylin and eosin staining. Pancreatic edema was estimated by measuring tissue water content. Tumor necrosis factor (TNF)-α and interleukin (IL)-6 level were measured by enzyme-linked immunosorbent assay. Pancreatic paracellular permeability was assessed by tissue dye extravasation. Expression of pancreatic claudin-5 and occludin was examined by immunohistology, quantitative real-time reverse transcriptase polymerase chain reaction and western blotting. RESULTS: Pancreatic TNF-α and IL-6 levels, wet/dry ratio, dye extravasation, and histological score were significantly elevated at 3, 6 and 12 h following sodium taurocholate infusion; treatment with emodin prevented these changes at all time points. Immunostaining of claudin-5 and occludin was detected in rat pancreas, which was distributed in pancreatic acinar cells, ductal cells and vascular endothelial cells, respectively. Sodium taurocholate infusion significantly decreased pancreatic claudin-5 and occludin mRNA and protein levels at 3, 6 and 12 h, and that could be promoted by intravenous administration of emodin at all time points. CONCLUSION: These results demonstrate that emodin could promote pancreatic claudin-5 and occludin expression, and reduce pancreatic paracellular permeability. PMID:22563203

  5. Regeneration of beta cells in islets of Langerhans of pancreas of alloxan diabetic rats by acetone extract of Momordica charantia (Linn.) (bitter gourd) fruits.

    PubMed

    Singh, Neera; Gupta, Manushma

    2007-12-01

    Acetone extract of whole fruit powder of M. charantia (bitter gourd) in doses 25, 50 and 75 mg/100 g body weight lowered the blood glucose from 13.30 to 50% after 8 to 30 days treatment in alloxan diabetic albino rats, confirming antihyperglycemic effect of this plant in diabetic animals and humans. Histological observations with acetone extract showed different phases of recovery of beta cells of the islets of Langerhans of pancreas, which in the untreated diabetic rats were less in number and showed varied degree of atrophy. The most important finding of the present study was observation of the presence of small scattered islets among the acinar tissue in some experimental animals, which may reflect neoformation of islets from pre-existing islet cells. The liver of alloxan diabetic rats showed hydropic degeneration, fatty change and necrosis at some places but liver of extract treated animals was normal. Glycogen localization in liver of diabetic rats was faint but after 30 days treatment with different doses of extract, normal to heavy glycogen localization was observed. PMID:18254212

  6. Isolation, characterization and potential role in beta cell-endothelium cross-talk of extracellular vesicles released from human pancreatic islets.

    PubMed

    Figliolini, Federico; Cantaluppi, Vincenzo; De Lena, Michela; Beltramo, Silvia; Romagnoli, Renato; Salizzoni, Mauro; Melzi, Raffaella; Nano, Rita; Piemonti, Lorenzo; Tetta, Ciro; Biancone, Luigi; Camussi, Giovanni

    2014-01-01

    The cross-talk between beta cells and endothelium plays a key role in islet physiopathology and in the revascularization process after islet transplantation. However, the molecular mechanisms involved in this cross-talk are not fully elucidated. Extracellular vesicles (EVs) are secreted membrane nanoparticles involved in inter-cellular communication through the transfer of proteins and nucleic acids. The aims of this study were: 1) isolation and characterization of EVs from human islets; 2) evaluation of the pro-angiogenic effect of islet-derived EVs on human islet endothelial cells (IECs). EVs were isolated by ultracentrifugation from conditioned medium of human islets and characterized by nanotrack analysis (Nanosight), FACS, western blot, bioanalyzer, mRNA/microRNA RT-PCR array. On IECs, we evaluated EV-induced insulin mRNA transfer, proliferation, resistance to apoptosis, in vitro angiogenesis, migration, gene and protein profiling. EVs sized 236±54 nm, expressed different surface molecules and islet-specific proteins (insulin, C-peptide, GLP1R) and carried several mRNAs (VEGFa, eNOS) and microRNAs (miR-27b, miR-126, miR-130 and miR-296) involved in beta cell function, insulin secretion and angiogenesis. Purified EVs were internalized into IECs inducing insulin mRNA expression, protection from apoptosis and enhancement of angiogenesis. Human islets release biologically active EVs able to shuttle specific mRNAs and microRNAs (miRNAs) into target endothelial cells. These results suggest a putative role for islet-derived EVs in beta cell-endothelium cross-talk and in the neoangiogenesis process which is critical for engraftment of transplanted islets. PMID:25028931

  7. Isolation, Characterization and Potential Role in Beta Cell-Endothelium Cross-Talk of Extracellular Vesicles Released from Human Pancreatic Islets

    PubMed Central

    De Lena, Michela; Beltramo, Silvia; Romagnoli, Renato; Salizzoni, Mauro; Melzi, Raffaella; Nano, Rita; Piemonti, Lorenzo; Tetta, Ciro; Biancone, Luigi; Camussi, Giovanni

    2014-01-01

    The cross-talk between beta cells and endothelium plays a key role in islet physiopathology and in the revascularization process after islet transplantation. However, the molecular mechanisms involved in this cross-talk are not fully elucidated. Extracellular vesicles (EVs) are secreted membrane nanoparticles involved in inter-cellular communication through the transfer of proteins and nucleic acids. The aims of this study were: 1) isolation and characterization of EVs from human islets; 2) evaluation of the pro-angiogenic effect of islet-derived EVs on human islet endothelial cells (IECs). EVs were isolated by ultracentrifugation from conditioned medium of human islets and characterized by nanotrack analysis (Nanosight), FACS, western blot, bioanalyzer, mRNA/microRNA RT-PCR array. On IECs, we evaluated EV-induced insulin mRNA transfer, proliferation, resistance to apoptosis, in vitro angiogenesis, migration, gene and protein profiling. EVs sized 236±54 nm, expressed different surface molecules and islet-specific proteins (insulin, C-peptide, GLP1R) and carried several mRNAs (VEGFa, eNOS) and microRNAs (miR-27b, miR-126, miR-130 and miR-296) involved in beta cell function, insulin secretion and angiogenesis. Purified EVs were internalized into IECs inducing insulin mRNA expression, protection from apoptosis and enhancement of angiogenesis. Human islets release biologically active EVs able to shuttle specific mRNAs and microRNAs (miRNAs) into target endothelial cells. These results suggest a putative role for islet-derived EVs in beta cell-endothelium cross-talk and in the neoangiogenesis process which is critical for engraftment of transplanted islets. PMID:25028931

  8. Activity of "nonspecific pancreatic carboxylesterase" in rat serum in experimentally induced acute pancreatitis (preliminary results).

    PubMed

    Kálmán, A; Kálmán, Z; Velösy, G; Vargha, G; Vargha, G; Papp, M

    1989-01-01

    The aim of this study was to obtain more information on the serum level of "nonspecific pancreatic carboxylesterase" (PCE) in experimentally induced acute pancreatitis in rats. The effects of caerulein stimulation, hepatic duct ligation, bile-pancreatic duct ligation or the effect of retrograde injection of saline, 5% taurocholate and sunflower oil were investigated. The activity of PCE and amylase was measured in the serum, pancreatic tissue, pancreatic juice and ascitic fluid. The changes in PCE activity were greater (both in directions to increase or decrease) than that of amylase, produced by different experimental procedures. The results confirm the thesis that the serum activity of PCE is a more sensitive diagnostic method than that of amylase to detect the inflammatory process in the pancreas or the effect of obstruction of the pancreatic duct. PMID:2480696

  9. MicroRNA-29a is up-regulated in beta-cells by glucose and decreases glucose-stimulated insulin secretion

    SciTech Connect

    Bagge, Annika; Clausen, Trine R.; Larsen, Sylvester; Ladefoged, Mette; Rosenstierne, Maiken W.; Larsen, Louise; Vang, Ole; Nielsen, Jens H.; Dalgaard, Louise T.

    2012-09-21

    Highlights: Black-Right-Pointing-Pointer MicroRNA-29a (miR-29a) levels are increased by glucose in human and rat islets and INS-1E cells. Black-Right-Pointing-Pointer miR-29a increases proliferation of INS-1E beta-cells. Black-Right-Pointing-Pointer Forced expression of miR-29a decreases glucose-stimulated insulin secretion (GSIS). Black-Right-Pointing-Pointer Depletion of beta-cell miR-29a improves GSIS. Black-Right-Pointing-Pointer miR-29a may be a mediator of glucose toxicity in beta-cells. -- Abstract: Chronically elevated levels of glucose impair pancreatic beta-cell function while inducing beta-cell proliferation. MicroRNA-29a (miR-29a) levels are increased in several tissues in diabetic animals and mediate decreased insulin-stimulated glucose-transport of adipocytes. The aim was to investigate the impact of glucose on miR-29a levels in INS-1E beta-cells and in human islets of Langerhans and furthermore to evaluate the impact of miR-29a on beta-cell function and proliferation. Increased glucose levels up-regulated miR-29a in beta-cells and human and rat islets of Langerhans. Glucose-stimulated insulin-secretion (GSIS) of INS-1E beta-cells was decreased by forced expression of miR-29a, while depletion of endogenous miR-29a improved GSIS. Over-expression of miR-29a increased INS-1E proliferation. Thus, miR-29a up-regulation is involved in glucose-induced proliferation of beta-cells. Furthermore, as depletion of miR-29a improves beta-cell function, miR-29a is a mediator of glucose-induced beta-cell dysfunction. Glucose-induced up-regulation of miR-29a in beta-cells could be implicated in progression from impaired glucose tolerance to type 2 diabetes.

  10. Protective role of sodium butyrate, a HDAC inhibitor on beta-cell proliferation, function and glucose homeostasis through modulation of p38/ERK MAPK and apoptotic pathways: study in juvenile diabetic rat.

    PubMed

    Khan, S; Jena, G B

    2014-04-25

    Type 1 diabetes (T1D) also known as juvenile diabetes is a chronic autoimmune disorder that precipitates in genetically susceptible individuals by environmental factors particularly during early age. Both genetic and epigenetic factors are implicated in the beta-cell development, proliferation, differentiation and function. Recent evidences suggested that there is a link between diabetes and histone deacetylases (HDACs), because HDAC inhibitors promote beta-cell development, proliferation and function as well as improve glucose homeostasis. Sodium butyrate (NaB) is a short chain fatty acid having HDAC inhibition activity. The present study was aimed to investigate the protective role of NaB treatment on the beta-cell proliferation, function and glucose homeostasis as well as apoptosis in juvenile diabetic rat. Diabetes was induced by single injection of STZ (60 mg/kg, i.p.) in chilled citrate buffer, while NaB (500 mg/kg/day) was administrated by i.p. route for 21 days as pre- and post-treatment schedule. Plasma glucose and insulin levels, HbA1c, glucose tolerance, apoptosis, and expression of proliferating cell nuclear antigen (PCNA), p38, p53, caspase-3, extracellular signal-regulated kinase-1/2 (ERK-1/2), forkhead box protein O1 (FOXO1) and insulin receptor substrate-1 (IRS-1) as well as histone acetylation were evaluated. NaB treatment decreased plasma glucose, HbA1c, beta-cell apoptosis and improved plasma insulin level and glucose homeostasis through HDAC inhibition and histone acetylation in diabetic animal as compared to control. NaB treatment improved the beta-cell proliferation, function and glucose homeostasis as well as reduced beta-cell apoptosis in juvenile diabetic rat by the modulation of p38/ERK MAPK and apoptotic pathway. PMID:24530320

  11. Diabetes in the Cohen Rat Intensifies the Fetal Pancreatic Damage Induced by the Diabetogenic High Sucrose Low Copper Diet.

    PubMed

    Ergaz, Zivanit; Neeman-Azulay, Meytal; Weinstein-Fudim, Liza; Weksler-Zangen, Sarah; Shoshani-Dror, Dana; Szyf, Moshe; Ornoy, Asher

    2016-02-01

    Intrauterine hyperglycemic environment could harm the fetus making it more susceptible to develop postnatal glucose intolerance. A possible mechanism is compromise of the fetal pancreatic development. We previously found that a high sucrose low copper diabetogenic diet induces type 2 diabetes in the Cohen diabetic sensitive rats, but not in the Sabra control rats. However, oxidative stress was observed in the placenta and term fetal liver of diabetic and nondiabetic controls. We now investigated whether the fetal pancreas is affected by this diet and whether the effects result from oxidative stress, maternal hyperglycemia, or both. Term fetal pancreases were evaluated for morphology, beta cells, oxidative stress, apoptosis, and DNA methylation. There were no microscopic changes in hematoxylin and eosin stained sections and beta cells immunostaining in the pancreas of fetuses of both strains. Fetuses of the sensitive strain fed diabetogenic diet had significantly higher activity of superoxide dismutase and catalase, elevated levels of low molecular weight antioxidants, and more intense immunostaining for nuclear factor kappa-B and hypoxia inducing factor-1α. Both strains fed diabetogenic diet had increased immunostaining for Bcl-2-like protein and caspase 3 and decreased immunostaining for 5-methylcytosine in their islets and acini. Our data suggest that maternal diabetogenic diet alters apoptotic rate and epigenetic steady states in the term fetal pancreas, unrelated to maternal diabetes. Maternal hyperglycemia further increases pancreatic oxidative stress, aggravating the pancreatic damage. The diet-induced insults to the fetal pancreas may be an important contributor to the high susceptibility to develop diabetes following metabolic intrauterine insults. PMID:26748987

  12. Ca2+-dependent dephosphorylation of kinesin heavy chain on beta-granules in pancreatic beta-cells. Implications for regulated beta-granule transport and insulin exocytosis

    NASA Technical Reports Server (NTRS)

    Donelan, Matthew J.; Morfini, Gerardo; Julyan, Richard; Sommers, Scott; Hays, Lori; Kajio, Hiroshi; Briaud, Isabelle; Easom, Richard A.; Molkentin, Jeffery D.; Brady, Scott T.; Rhodes, Christopher J.

    2002-01-01

    The specific biochemical steps required for glucose-regulated insulin exocytosis from beta-cells are not well defined. Elevation of glucose leads to increases in cytosolic [Ca2+]i and biphasic release of insulin from both a readily releasable and a storage pool of beta-granules. The effect of elevated [Ca2+]i on phosphorylation of isolated beta-granule membrane proteins was evaluated, and the phosphorylation of four proteins was found to be altered by [Ca2+]i. One (a 18/20-kDa doublet) was a Ca2+-dependent increase in phosphorylation, and, surprisingly, three others (138, 42, and 36 kDa) were Ca2+-dependent dephosphorylations. The 138-kDa beta-granule phosphoprotein was found to be kinesin heavy chain (KHC). At low levels of [Ca2+]i KHC was phosphorylated by casein kinase 2, but KHC was rapidly dephosphorylated by protein phosphatase 2B beta (PP2Bbeta) as [Ca2+]i increased. Inhibitors of PP2B specifically reduced the second, microtubule-dependent, phase of insulin secretion, suggesting that dephosphorylation of KHC was required for transport of beta-granules from the storage pool to replenish the readily releasable pool of beta-granules. This is distinct from synaptic vesicle exocytosis, because neurotransmitter release from synaptosomes did not require a Ca2+-dependent KHC dephosphorylation. These results suggest a novel mechanism for regulating KHC function and beta-granule transport in beta-cells that is mediated by casein kinase 2 and PP2B. They also implicate a novel regulatory role for PP2B/calcineurin in the control of insulin secretion downstream of a rise in [Ca2+]i.

  13. Everolimus and Octreotide Acetate With or Without Bevacizumab in Treating Patients With Locally Advanced or Metastatic Pancreatic Neuroendocrine Tumors That Cannot Be Removed by Surgery

    ClinicalTrials.gov

    2016-06-20

    Gastrin-Producing Neuroendocrine Tumor; Malignant Pancreatic Gastrinoma; Malignant Pancreatic Glucagonoma; Malignant Pancreatic Insulinoma; Malignant Pancreatic Somatostatinoma; Pancreatic Alpha Cell Adenoma; Pancreatic Beta Cell Adenoma; Pancreatic Delta Cell Adenoma; Pancreatic G-Cell Adenoma; Pancreatic Glucagonoma; Pancreatic Insulinoma; Pancreatic Polypeptide Tumor; Recurrent Pancreatic Carcinoma; Recurrent Pancreatic Neuroendocrine Carcinoma; Somatostatin-Producing Neuroendocrine Tumor; Stage III Pancreatic Cancer; Stage IV Pancreatic Cancer

  14. Monitoring of beta cell replacement outcomes.

    PubMed

    Chang, Charles A; Haque, Waqas Z; Yoshimatsu, Gumpei; Balajii, Prathab S; Lawrence, Michael C; Naziruddin, Bashoo

    2016-03-01

    Pancreatic islet transplantation is a promising beta cell replacement treatment for patients with "brittle" type 1 diabetes (T1D) or intractable chronic pancreatitis to restore or preserve pancreatic endocrine function. Early after transplant, a significant islet mass is lost due to an innate inflammatory response, and further loss of the islet graft occurs over time due to immune response, drug toxicity, or metabolic exhaustion. Thus, clinically feasible techniques are essential to monitor islet graft function and survival to maintain appropriate therapy. Currently, islet graft function is monitored using blood glucose levels, insulin and C-peptide levels, and islet imaging. However, these tests are influenced by physiological changes, including beta cell stimulation. Biomarkers that are independent of metabolic stimuli would be more accurate and reliable in detecting islet damage. Antibodies against islet autoantigens are useful but not reliable markers of islet injury due to their presence during the pretransplant period. Several islet-specific proteins such as Glutamate decarboxylase-65, doublecortin, protein phosphatase 1, regulatory (inhibitor) subunit 1A, ubiquitin C-terminal hydrolase-L1, and the high-mobility group box-1 protein have been proposed as candidates to monitor islet damage, but these biomarkers have short half-lives and unreliable detection. Unmethylated insulin DNA has been studied in T1D patients and has been documented as a highly correlative and selective biomarker for beta cell death. More recently, microRNAs (miRNAs) that are selectively expressed in islets have been shown to provide sensitive and accurate quantification of islet damage. Analysis of plasma samples from autologous and allogeneic islet transplant patients has demonstrated the value of miRNA-375 as a specific biomarker to accurately assess islet damage. Use of selective, sensitive, and measurably reproducible biomarkers of islets will lead to effective monitoring of beta

  15. One-step purification of functional human and rat pancreatic alpha cells.

    PubMed

    Köhler, Martin; Daré, Elisabetta; Ali, Muhammed Yusuf; Rajasekaran, Subu Surendran; Moede, Tilo; Leibiger, Barbara; Leibiger, Ingo B; Tibell, Annika; Juntti-Berggren, Lisa; Berggren, Per-Olof

    2012-02-01

    Pancreatic alpha cells contribute to glucose homeostasis by the regulated secretion of glucagon, which increases glycogenolysis and hepatic gluconeogenesis in response to hypoglycemia. Alterations of glucagon secretion are observed in diabetic patients and exacerbate the disease. The restricted availability of purified primary alpha cells has limited our understanding of their function in health and disease. This study was designed to establish convenient protocols for the purification of viable alpha cells from rat and human pancreatic islets by FACS, using intrinsic cellular properties. Islets were isolated from the pancreata of Wistar rats or deceased human organ donors. Dispersed islet cells were separated by FACS based on light scatter and autofluorescence. Purity of sorted cells was evaluated by immunocytochemistry using hormone specific antibodies. Relative hormone expression was further determined by quantitative RT-PCR. Viability was determined by Annexin V and propidium iodide staining and function was assessed by monitoring cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) using Fura-2/AM. We developed species-specific FACS gating strategies that resulted in populations consisting mainly of alpha cells (96.6 ± 1.4%, n = 3 for rat; 95.4 ± 1.7%, n = 4 for human, mean ± SEM). These cell fractions showed ~5-fold and ~4-fold enrichment (rat and human, respectively) of glucagon mRNA expression compared to total ungated islet cells. Most of the sorted cells were viable and functional, as they responded with an increase in [Ca(2+)](i) upon stimulation with L-arginine (10 mM). The majority of the sorted human alpha cells responded also to stimulation with kainate (100 μM), whereas this response was infrequent in rat alpha cells. Using the same sample preparation, but a different gating strategy, we were also able to sort rat and human populations enriched in beta cells. In conclusion, we have simplified and optimized a method for the purification of rat

  16. Intravenous contrast medium aggravates the impairment of pancreatic microcirculation in necrotizing pancreatitis in the rat.

    PubMed Central

    Schmidt, J; Hotz, H G; Foitzik, T; Ryschich, E; Buhr, H J; Warshaw, A L; Herfarth, C; Klar, E

    1995-01-01

    BACKGROUND: Previous reports demonstrated that radiographic contrast medium, as used in contrast-enhanced computed tomography, increases acinar necrosis and mortality in experimental pancreatitis. The authors studied the possibility that these changes may be related to an additional impairment of pancreatic microcirculation. METHODS: Fifty Wistar rats had acute pancreatitis induced by intraductal glycodeoxycholic acid (10 mmol/L for 10 min) and intravenous cerulein (5 micrograms/kg/hr for 6 hrs). After rehydration (16 mL/kg), pancreatic capillary perfusion was quantified by means of intravital microscopy at baseline before intravenous infusion of contrast medium (n = 25) or saline (n = 25), and 30 and 60 minutes thereafter. In addition to total capillary flow, capillaries were categorized as high- or low-flow (> or < 1.6 nL/min). RESULTS: Pancreatic capillary flow did not change in either high- or low-flow capillaries after saline infusion. However, contrast medium infusion induced a significant decrease of total capillary flow (p < 0.001). Analysis according to the relative flow rate revealed that this was primarily because of a significant additional reduction of perfusion in low-flow capillaries (p < 0.0001). Furthermore, complete capillary stasis was observed in 15.9 +/- 3.4% after contrast medium as compared with 3.2 +/- 1.2% after saline infusion (p < 0.006). CONCLUSION: Radiographic contrast medium aggravates the impairment of pancreatic microcirculation in experimental necrotizing pancreatitis. PMID:7717779

  17. Proteomic analysis of pancreatic intraepithelial neoplasia and pancreatic carcinoma in rat models

    PubMed Central

    Wang, Lei; Liu, Hai-Lin; Li, Ya; Yuan, Ping

    2011-01-01

    AIM: To detect the proteomic variabilities of pancreatic intraepithelial neoplasia (PanIN) and pancreatic carcinoma (PC) induced by 7,12-dimethylbenzanthracene (DMBA) in rat models and to identify potential biomarkers. METHODS: Sixty adult male Sprague Dawley rats were randomized into three groups. The rats had DMBA implanted into their pancreas for one (n = 20) or two months (n = 20) or assigned to the normal group (n = 20). The rats were killed after one or two months, and were evaluated histopathologically. Three tissue samples from each group of rats with either normal pancreas, PanIN (PanIN-2) or PC were examined by 2D-DIGE. The different expression spot features were analyzed by matrix-assisted laser desorption/ionization-time of flight/time of flight (MALDI-TOF/TOF) tandem mass spectrometry. The expression of enolase 1, a differentially expressed protein, was identified by immunohistochemistry. RESULTS: There was significant difference in the proportions of neoplastic changes between the 1- and 2-mogroups (P = 0.0488). There was an increase in the frequency of adenocarcinomas in the 2-mo group compared with the 1-mo group (P = 0.0309). No neoplastic changes were observed in any of the animals in the normal group. Enolase 1, pancreatic ELA3B, necdin, Hbp23, CHD3, hnRNP A2/B1, Rap80, and Gnb2l1 were up-regulated in the PanIN and PC tissues, and CEL, TPT1, NME2, PCK2, an unnamed protein product, and glycine C-acetyltransferase were down-regulated in the PanIN and PC tissues. The immunohistochemical results showed that enolase 1 expression was up-regulated in the pancreatic cancer tissues of rats and humans. CONCLUSION: The pancreatic protein expression changes induced by DMBA suggest potential molecular targets for the early diagnosis and treatment of PC. PMID:21472101

  18. Curcumin enhances recovery of pancreatic islets from cellular stress induced inflammation and apoptosis in diabetic rats

    SciTech Connect

    Rashid, Kahkashan; Sil, Parames C.

    2015-02-01

    The phytochemical, curcumin, has been reported to play many beneficial roles. However, under diabetic conditions, the detail mechanism of its beneficial action in the glucose homeostasis regulatory organ, pancreas, is poorly understood. The present study has been designed and carried out to explore the role of curcumin in the pancreatic tissue of STZ induced and cellular stress mediated diabetes in eight weeks old male Wistar rats. Diabetes was induced with a single intraperitoneal dose of STZ (65 mg/kg body weight). Post to diabetes induction, animals were treated with curcumin at a dose of 100 mg/kg body weight for eight weeks. Underlying molecular and cellular mechanism was determined using various biochemical assays, DNA fragmentation, FACS, histology, immunoblotting and ELISA. Treatment with curcumin reduced blood glucose level, increased plasma insulin and mitigated oxidative stress related markers. In vivo and in vitro experimental results revealed increased levels of proinflammatory cytokines (TNF-α, IL1-β and IFN-γ), reduced level of cellular defense proteins (Nrf-2 and HO-1) and glucose transporter (GLUT-2) along with enhanced levels of signaling molecules of ER stress dependent and independent apoptosis (cleaved Caspase-12/9/8/3) in STZ administered group. Treatment with curcumin ameliorated all the adverse changes and helps the organ back to its normal physiology. Results suggest that curcumin protects pancreatic beta-cells by attenuating inflammatory responses, and inhibiting ER/mitochondrial dependent and independent pathways of apoptosis and crosstalk between them. This uniqueness and absence of any detectable adverse effect proposes the possibility of using this molecule as an effective protector in the cellular stress mediated diabetes mellitus. - Highlights: • STZ induced cellular stress plays a vital role in pancreatic dysfunction. • Cellular stress causes inflammation, pancreatic islet cell death and diabetes. • Deregulation of Nrf-2

  19. The expression of dominant negative TCF7L2 in pancreatic beta cells during the embryonic stage causes impaired glucose homeostasis

    PubMed Central

    Shao, Weijuan; Xiong, Xiaoquan; Ip, Wilfred; Xu, Fenghao; Song, Zhuolun; Zeng, Kejing; Hernandez, Marcela; Liang, Tao; Weng, Jianping; Gaisano, Herbert; Nostro, M. Cristina; Jin, Tianru

    2015-01-01

    Objective Disruption of TCF7L2 in mouse pancreatic β-cells has generated different outcomes in several investigations. Here we aim to clarify role of β-cell TCF7L2 and Wnt signaling using a functional-knockdown approach. Methods Adenovirus-mediated dominant negative TCF7L2 (TCF7L2DN) expression was conducted in Ins-1 cells. The fusion gene in which TCF7L2DN expression is driven by PTRE3G was utilized to generate the transgenic mouse line TCF7L2DNTet. The double transgenic line was created by mating TCF7L2DNTet with Ins2-rtTA, designated as βTCFDN. β-cell specific TCF7L2DN expression was induced in βTCFDN by doxycycline feeding. Results TCF7L2DN expression in Ins-1 cells reduced GSIS, cell proliferation and expression of a battery of genes including incretin receptors and β-cell transcription factors. Inducing TCF7L2DN expression in βTCFDN during adulthood or immediately after weaning generated no or very modest metabolic defect, while its expression during embryonic development by doxycycline feeding in pregnant mothers resulted in significant glucose intolerance associated with altered β-cell gene expression and reduced β-cell mass. Conclusions Our observations support a cell autonomous role for TCF7L2 in pancreatic β-cells suggested by most, though not all, investigations. βTCFDN is a novel model for further exploring the role of TCF7L2 in β-cell genesis and metabolic homeostasis. PMID:25830097

  20. Targeting insulin-producing beta cells for regenerative therapy.

    PubMed

    Migliorini, Adriana; Roscioni, Sara S; Lickert, Heiko

    2016-09-01

    Pancreatic beta cells differ in terms of glucose responsiveness, insulin secretion and proliferative capacity; however, the molecular pathways that regulate this cellular heterogeneity are unknown. We have identified the Wnt-planar cell polarity (PCP) effector Flattop (FLTP) as a biomarker that identifies mature beta cells in the islets of Langerhans. Interestingly, three-dimensional architecture and Wnt-PCP ligands are sufficient to trigger mouse and human beta cell maturation. These results highlight the fact that novel biomarkers shed light on the long-standing mystery of beta cell heterogeneity and identify the Wnt-PCP pathway as triggering beta cell maturation. Understanding heterogeneity in the islets of Langerhans might allow targeting of beta cell subpopulations for regenerative therapy and provide building principles for stem cell-derived islets. This review summarises a presentation given at the 'Can we make a better beta cell?' symposium at the 2015 annual meeting of the EASD. It is accompanied by two other reviews on topics from this symposium (by Amin Ardestani and Kathrin Maedler, DOI: 10.1007/s00125-016-3892-9 , and by Harry Heimberg and colleagues, DOI: 10.1007/s00125-016-3879-6 ) and a commentary by the Session Chair, Shanta Persaud (DOI: 10.1007/s00125-016-3870-2 ). PMID:27412250

  1. Muscarinic receptors and amylase secretion of rat pancreatic acini during cerulein-induced acute pancreatitis.

    PubMed

    Morisset, J; Wood, J; Solomon, T E; Larose, L

    1987-08-01

    This study examines the effects of cerulein-induced acute pancreatitis on the secretory response of rat pancreatic acini to carbamylcholine and concentration of acinar muscarinic receptors. Rats were injected subcutaneously every 8 hr with cerulein, 12 micrograms/kg, for two days. They were sacrificed 2 and 4 hr after the first injection, 4 hr after the second and third, and 8 hr after the sixth. By 2 hr after the first injection, carbamylcholine showed decreased potency for stimulating amylase release; decreased potency becomes maximal after the second injection. Four hours after the first injection, carbamylcholine also showed decreased efficacy for causing maximal amylase release. In the course of development of pancreatitis, progressive reductions in muscarinic receptor concentrations were evident from 4 hr after the second injection. Following the complete treatment (8 hr after the sixth injection), no alteration could be observed in the affinity or proportions of each agonist class of muscarinic receptors. These studies indicate that the pancreatic acinar cells still remain functional after acute cerulein-induced pancreatitis, although significant reductions in potency and efficacy of carbamylcholine to cause amylase release and reduced muscarinic receptor concentration occur. PMID:2440647

  2. Intestinal disaccharidase activity following pancreatic duct occlusion in the rat.

    PubMed

    Hauer-Jensen, M; Christensen, K; Wilson, H D; Schedl, H P

    1987-01-01

    The influence of pancreatic secretions on growth and brush-border enzyme activity, throughout the entire small intestine, was examined in the rat. Pancreatic secretions were excluded from the gut lumen by stapling the pancreatic ducts, without interruption of bile flow. The entire small intestine was studied as four segments; the duodenum and three distal segments of equal length. Weight of intestine and mucosa, and mucosal sucrase, isomaltase, lactase, and alkaline phosphatase activity were measured 10-15 days following pancreatic duct occlusion, or sham-operation. The duodenum of pancreatic duct-occluded animals exhibited significant hypertrophy. In general, specific and total disaccharidase activities were greater in duct-occluded animals than in controls throughout the intestine. The increase was more pronounced in distal than in proximal segments. The sucrase/isomaltase ratio was significantly greater in pancreatic duct-occluded animals than in controls in the two distal segments. Alkaline phosphatase activity was not affected by pancreatic duct occlusion. The greater relative increase of disaccharidase activities and sucrase/isomaltase activity ratios in the distal segments of duct-occluded animals, indicates a more important regulatory role of pancreatic enzymes in the distal small intestine. It is concluded that regulation of intestinal brush-border enzyme activity by pancreatic secretion is selective for enzyme and site as follows: disaccharidases, but not alkaline phosphatase, are regulated; the sucrase subunit of the sucrase/isomaltase complex is most sensitive to regulation, while lactase is least sensitive; and the regulatory effect on disaccharidases is greater in distal than in proximal intestine. PMID:3114740

  3. Maturation of Stem Cell-Derived Beta-cells Guided by the Expression of Urocortin 3

    PubMed Central

    van der Meulen, Talitha; Huising, Mark O.

    2014-01-01

    Type 1 diabetes (T1D) is a devastating disease precipitated by an autoimmune response directed at the insulin-producing beta-cells of the pancreas for which no cure exists. Stem cell-derived beta-cells show great promise for a cure as they have the potential to supply unlimited numbers of cells that could be derived from a patient's own cells, thus eliminating the need for immunosuppression. Current in vitro protocols for the differentiation of stem cell-derived beta-cells can successfully generate pancreatic endoderm cells. In diabetic rodents, such cells can differentiate further along the beta-cell lineage until they are eventually capable of restoring normoglycemia. While these observations demonstrate that stem cell-derived pancreatic endoderm has the potential to differentiate into mature, glucose-responsive beta-cells, the signals that direct differentiation and maturation from pancreatic endoderm onwards remain poorly understood. In this review, we analyze the sequence of events that culminates in the formation of beta-cells during embryonic development. and summarize how current protocols to generate beta-cells have sought to capitalize on this ontogenic template. We place particular emphasis on the current challenges and opportunities which occur in the later stages of beta-cell differentiation and maturation of transplantable stem cell-derived beta-cells. Another focus is on the question how the use of recently identified maturation markers such as urocortin 3 can be instrumental in guiding these efforts. PMID:25148370

  4. Glucagon-Like Peptide-1 Receptor Agonists: Beta-Cell Protection or Exhaustion?

    PubMed

    van Raalte, Daniël H; Verchere, C Bruce

    2016-07-01

    Glucagon-like peptide (GLP)-1 receptor agonists enhance insulin secretion and may improve pancreatic islet cell function. However, GLP-1 receptor (GLP-1R) agonist treatment may have more complex, and sometimes deleterious, effects on beta cells. We discuss the concepts of beta cell protection versus exhaustion for different GLP-1R agonists based on recent data. PMID:27160799

  5. Bone marrow-derived pancreatic stellate cells in rats.

    PubMed

    Sparmann, Gisela; Kruse, Marie-Luise; Hofmeister-Mielke, Nicole; Koczan, Dirk; Jaster, Robert; Liebe, Stefan; Wolff, Daniel; Emmrich, Jörg

    2010-03-01

    Origin and fate of pancreatic stellate cells (PSCs) before, during and after pancreatic injury are a matter of debate. The crucial role of PSCs in the pathogenesis of pancreatic fibrosis is generally accepted. However, the turnover of the cells remains obscure. The present study addressed the issue of a potential bone marrow (BM) origin of PSCs. We used a model of stable hematopoietic chimerism by grafting enhanced green fluorescence protein (eGFP)-expressing BM cells after irradiation of acceptor rats. Chimerism was detected by FACS analysis of eGFP-positive cells in the peripheral blood. Dibutyltin dichloride (DBTC) was used to induce acute pancreatic inflammation with subsequent recovery over 4 weeks. Investigations have been focused on isolated cells to detect the resting PSC population. The incidence of eGFP-positive PSC obtained from the pancreas of chimeric rats was approximately 7% in healthy pancreatic tissue and increased significantly to a mean of 18% in the restored pancreas 4 weeks after DBTC-induced acute inflammation. Our results suggest that BM-derived progenitor cells represent a source of renewable stellate cells in the pancreas. Increased numbers of resting PSCs after regeneration point toward enhanced recruitment of BM-derived cells to the pancreas and/or re-acquisition of a quiescent state after inflammation-induced activation. PMID:20101265

  6. BPC 157 therapy to detriment sphincters failure-esophagitis-pancreatitis in rat and acute pancreatitis patients low sphincters pressure.

    PubMed

    Petrovic, I; Dobric, I; Drmic, D; Sever, M; Klicek, R; Radic, B; Brcic, L; Kolenc, D; Zlatar, M; Kunjko, K; Jurcic, D; Martinac, M; Rasic, Z; Boban Blagaic, A; Romic, Z; Seiwerth, S; Sikiric, P

    2011-10-01

    Possibly, acute esophagitis and pancreatitis cause each other, and we focused on sphincteric failure as the common causative key able to induce either esophagitis and acute pancreatitis or both of them, and thereby investigate the presence of a common therapy nominator. This may be an anti-ulcer pentadecapeptide BPC 157 (tested for inflammatory bowel disease, wound treatment) affecting esophagitis, lower esophageal and pyloric sphincters failure and acute pancreatitis (10 μg/kg, 10 ng/kg intraperitoneally or in drinking water). The esophagitis-sphincter failure procedure (i.e., insertion of the tubes into the sphincters, lower esophageal and pyloric) and acute pancreatitis procedure (i.e., bile duct ligation) were combined in rats. Esophageal manometry was done in acute pancreatitis patients. In rats acute pancreatitis procedure produced also esophagitis and both sphincter failure, decreased pressure 24 h post-surgery. Furthermore, bile duct ligation alone immediately declines the pressure in both sphincters. Vice versa, the esophagitis-sphincter failure procedure alone produced acute pancreatitis. What's more, these lesions (esophagitis, sphincter failure, acute pancreatitis when combined) aggravate each other (tubes into sphincters and ligated bile duct). Counteraction occurred by BPC 157 therapies. In acute pancreatitis patients lower pressure at rest was in both esophageal sphincters in acute pancreatitis patients. We conclude that BPC 157 could cure esophagitis/sphincter/acute pancreatitis healing failure. PMID:22204800

  7. The role of the innate immune system in destruction of pancreatic beta cells in NOD mice and humans with type I diabetes.

    PubMed

    Tai, Ningwen; Wong, F Susan; Wen, Li

    2016-07-01

    Type 1 diabetes (T1D) is an organ-specific autoimmune disease characterized by T cell-mediated destruction of the insulin-producing pancreatic β cells. A combination of genetic and environmental factors eventually leads to the loss of functional β cell mass and hyperglycemia. Both innate and adaptive immunity are involved in the development of T1D. In this review, we have highlighted the most recent findings on the role of innate immunity, especially the pattern recognition receptors (PRRs), in disease development. In murine models and human studies, different PRRs, such as toll-like receptors (TLRs) and nucleotide-binding domain, leucine-rich repeat-containing (or Nod-like) receptors (NLRs), have different roles in the pathogenesis of T1D. These PRRs play a critical role in defending against infection by sensing specific ligands derived from exogenous microorganisms to induce innate immune responses and shape adaptive immunity. Animal studies have shown that TLR7, TLR9, MyD88 and NLPR3 play a disease-predisposing role in T1D, while controversial results have been found with other PRRs, such as TLR2, TLR3, TLR4, TLR5 and others. Human studies also shown that TLR2, TLR3 and TLR4 are expressed in either islet β cells or infiltrated immune cells, indicating the innate immunity plays a role in β cell autoimmunity. Furthermore, some human genetic studies showed a possible association of TLR3, TLR7, TLR8 or NLRP3 genes, at single nucleotide polymorphism (SNP) level, with human T1D. Increasing evidence suggest that the innate immunity modulates β cell autoimmunity. Thus, targeting pathways of innate immunity may provide novel therapeutic strategies to fight this disease. PMID:27021275

  8. Partial regeneration of beta-cells in the islets of Langerhans by Nymphayol a sterol isolated from Nymphaea stellata (Willd.) flowers.

    PubMed

    Subash-Babu, P; Ignacimuthu, S; Agastian, P; Varghese, Babu

    2009-04-01

    Reduction of the beta-cell mass is critical in the pathogenesis of diabetes mellitus. The discovery of agents which induce regeneration of pancreatic beta-cells would be useful to develop new therapeutic approaches to treat diabetes. The present study was aimed at identifying a new agent for the control of diabetes through regeneration of pancreatic beta cells and insulin secretory potential. Nymphaea stellata flower chloroform extract (NSFCExt) showed significant plasma glucose lowering effect. Further NSFCExt was utilized to isolate and identify the lead compound based on bioassay guided fractionation; we found Nymphayol (25,26-dinorcholest-5-en-3beta-ol) a new crystal [space group P2(1) (No. 4), a=9.618(5), b=7.518(5), c=37.491(5)]. It was purified by repeat column. The structure was determined on the basis of X-ray crystallography and spectral data. Oral administration of Nymphayol for 45 days significantly (p<0.05) lowered the blood glucose level and more importantly it effectively increased the insulin content in diabetic rats. In addition, Nymphayol increased the number of beta cell mass enormously. Islet-like cell clusters in the islets of Langerhans were clearly observed based on histochemical and immunohistochemical study. PMID:19272781

  9. Beta-cell-specific production of IL6 in conjunction with a mainly intracellular but not mainly surface viral protein causes diabetes

    PubMed Central

    Van Belle, Tom L.; Pagni, Philippe P.; Liao, Jeanette; Sachithanantham, Sowbarnika; Dave, Amy; Hani, Amira Bel; Manenkova, Yulia; Amirian, Natalie; Yang, Cheng; Morin, Bret; Zhang, Haiqing; Campbell, Iain L.; von Herrath, Matthias G.

    2014-01-01

    Inflammatory mechanisms play a key role in the pathogenesis of type 1 and type 2 diabetes. IL6, a pleiotropic cytokine with impact on immune and non-immune cell types, has been proposed to be involved in the events causing both forms of diabetes and to play a key role in experimental insulin-dependent diabetes development. The aim of this study was to investigate how beta-cell specific overexpression of IL-6 influences diabetes development. We developed two lines of rat insulin promoter (RIP)-lymphocytic choriomeningitis virus (LCMV) mice that also co-express IL6 in their beta-cells. Expression of the viral nucleoprotein (NP), which has a predominantly intracellular localization, together with IL6 led to hyperglycemia, which was associated with a loss of GLUT-2 expression in the pancreatic beta-cells and infiltration of CD11b+ cells, but not T cells, in the pancreas. In contrast, over-expression of the LCMV glycoprotein (GP), which can localize to the surface, with IL-6 did not lead to spontaneous diabetes, but accelerated virus-induced diabetes by increasing autoantigen-specific CD8+ T cell responses and reducing the regulatory T cell fraction, leading to increased pancreatic infiltration by CD4+ and CD8+ T cells as well as CD11b+ and CD11c+ cells. The production of IL-6 in beta-cells acts prodiabetic, underscoring the potential benefit of targeting IL6 in diabetes. PMID:24582317

  10. WS6 induces both alpha and beta cell proliferation without affecting differentiation or viability

    PubMed Central

    Boerner, Brian P.; George, Nicholas M.; Mir, Shakeel U.R.; Sarvetnick, Nora E.

    2016-01-01

    Agents that stimulate human pancreatic beta cell proliferation are needed to improve diabetes mellitus treatment. Recently, a small molecule, WS6, was observed to stimulate human beta cell proliferation. However, little is known about its other effects on human islets. To better understand the role of WS6 as a possible beta cell regenerative therapy, we carried out in-depth phenotypic analysis of WS6-treated human islets, exploring its effects on non-beta cell proliferation, beta cell differentiation, and islet cell viability. WS6 not only stimulated beta cell proliferation in cultured human islets (in agreement with previous reports), but also human alpha cell proliferation, indicating that WS6 is not a beta cell-specific mitogen. WS6 did not change the proportion of insulin-positive beta cells or the expression of beta cell-specific transcription factors, suggesting that WS6 does not alter beta cell differentiation, and WS6 had no effect on human islet cell apoptosis or viability. In conclusion, WS6 stimulates proliferation of both human beta and alpha cells while maintaining cellular viability and the beta cell differentiated phenotype. These findings expand the literature on WS6 and support the suggestion that WS6 may help increase human islet mass needed for successful treatment of diabetes. PMID:25739404

  11. Vitamin D3 supplementation increases insulin level by regulating altered IP3 and AMPA receptor expression in the pancreatic islets of streptozotocin-induced diabetic rat.

    PubMed

    Jayanarayanan, Sadanandan; Anju, Thoppil R; Smijin, Soman; Paulose, Cheramadathikudiyil Skaria

    2015-10-01

    Pancreatic islets, particularly insulin-secreting β cells, share common characteristics with neurons. Glutamate is one of the major excitatory neurotransmitter in the brain and pancreas, and its action is mediated through glutamate receptors. In the present work, we analysed the role of vitamin D3 in the modulation of AMPA receptor subunit and their functional role in insulin release. Radio receptor binding study in diabetic rats showed a significant increase in AMPA receptor density. Insulin AMPA colabelling study showed an altered AMPA GluR2 and GluR4 subunit expression in the pancreatic beta cells. We also found lowered IP3 content and decreased IP3 receptor in pancreas of diabetic rats. The alterations in AMPA and IP3 receptor resulted in reduced cytosolic calcium level concentration, which further blocks Ca(2+)-mediated insulin release. Vitamin D3 supplementation restored the alteration in vitamin D receptor expression, AMPA receptor density and AMPA and IP3 receptor expression in the pancreatic islets that helps to restore the calcium-mediated insulin secretion. Our study reveals the antidiabetic property of vitamin D3 that is suggested to have therapeutic role through regulating glutamatergic function in diabetic rats. PMID:26054778

  12. Pancreatic and Pancreatic-Like Microbial Proteases Accelerate Gut Maturation in Neonatal Rats

    PubMed Central

    Prykhodko, Olena; Pierzynowski, Stefan G.; Nikpey, Elham; Arevalo Sureda, Ester; Fedkiv, Olexandr; Weström, Björn R.

    2015-01-01

    Objectives Postnatal gut maturation in neonatal mammals, either at natural weaning or after precocious inducement, is coinciding with enhanced enzymes production by exocrine pancreas. Since the involvement of enzymes in gut functional maturation was overlooked, the present study aimed to investigate the role of enzymes in gut functional maturation using neonatal rats. Methods Suckling rats (Rattus norvegicus) were instagastrically gavaged with porcine pancreatic enzymes (Creon), microbial-derived amylase, protease, lipase and mixture thereof, while controls received α-lactalbumin or water once per day during 14–16 d of age. At 17 d of age the animals were euthanized and visceral organs were dissected, weighed and analyzed for structural and functional properties. For some of the rats, gavage with the macromolecular markers such as bovine serum albumin and bovine IgG was performed 3 hours prior to blood collection to assess the intestinal permeability. Results Gavage with the pancreatic or pancreatic-like enzymes resulted in stimulated gut growth, increased gastric acid secretion and switched intestinal disaccharidases, with decreased lactase and increased maltase and sucrase activities. The fetal-type vacuolated enterocytes were replaced by the adult-type in the distal intestine, and macromolecular transfer to the blood was declined. Enzyme exposure also promoted pancreas growth with increased amylase and trypsin production. These effects were confined to the proteases in a dose-dependent manner. Conclusion Feeding exogenous enzymes, containing proteases, induced precocious gut maturation in suckling rats. This suggests that luminal exposure to proteases by oral loading or, possibly, via enhanced pancreatic secretion involves in the gut maturation of young mammals. PMID:25658606

  13. Quantitative Assessment of Proliferative Effects of Oral Vanadium on Pancreatic Islet Volumes and Beta Cell Numbers of Diabetic Rats

    PubMed Central

    Pirmoradi, Leila; Noorafshan, Ali; Safaee, Akbar; Dehghani, Gholam Abbas

    2016-01-01

    Background: Oral vanadyl sulfate (vanadium) induces normoglycemia, proliferates beta cells and prevents pancreatic islet atrophy in streptozotocin-induced diabetic rats. Soteriological method is used to quantitate the proliferative effects of vanadium on beta-cell numbers and islet volumes of normal and diabetic rats. Methods: Adult male Sprague-Dawley rats were made diabetic with intravenous streptozotocin injection (40 mg/kg). Normal and diabetic rats were divided into four groups. While control normal and diabetic (CD) groups used water, vanadium-treated normal (VTN) and diabetic (VTD) groups used solutions containing vanadyl sulfate (0.5-1 mg/mL, VOSO4+5H2O). Tail blood samples were used to measure blood glucose (BG) and plasma insulin. Two months after treatment, rats were sacrificed, pancreata prepared, and stereology method was used to quantitatively evaluate total beta cell numbers (TBCN) and total islet volumes (TISVOL). Results: Normoglycemia persisted in VTN with significantly decreased plasma insulin (0.190.08 vs. 0.970.27 ng/dL, P<0.002). The respective high BG (53249 vs. 14446 mg/dL, P<0.0001) and reduced plasma insulin (0.260.15 vs. 0.540.19 ng/dL, P<0.002) seen in CD were reversed in VTD during vanadium treatment or withdrawal. While the induction of diabetes, compared to their control, significantly decreased TISVOL (1.90.2 vs. 3.030.6 mm3, P<0.003) and TBCN (0.990.1 vs. 3.20.2 x 106, P<0.003), vanadium treatment significantly increased TISVOL (2.90.8 and 4.071.0 mm3, P<0.003) and TBCN (1.50.3 and 3.80.6 x 106, P<0.03). Conclusion: Two-month oral vanadium therapy in STZ-diabetic rats ameliorated hyperglycemia by partially restoring plasma insulin. This action was through proliferative actions of vanadium in preventing islet atrophy by increasing beta-cell numbers. PMID:26459400

  14. Quantitative-Proteomic Comparison of Alpha and Beta Cells to Uncover Novel Targets for Lineage Reprogramming

    PubMed Central

    Mertins, Philipp; Udeshi, Namrata D.; Dančík, Vlado; Fomina-Yadlin, Dina; Kubicek, Stefan; Clemons, Paul A.; Schreiber, Stuart L.; Carr, Steven A.; Wagner, Bridget K.

    2014-01-01

    Type-1 diabetes (T1D) is an autoimmune disease in which insulin-secreting pancreatic beta cells are destroyed by the immune system. An emerging strategy to regenerate beta-cell mass is through transdifferentiation of pancreatic alpha cells to beta cells. We previously reported two small molecules, BRD7389 and GW8510, that induce insulin expression in a mouse alpha cell line and provide a glimpse into potential intermediate cell states in beta-cell reprogramming from alpha cells. These small-molecule studies suggested that inhibition of kinases in particular may induce the expression of several beta-cell markers in alpha cells. To identify potential lineage reprogramming protein targets, we compared the transcriptome, proteome, and phosphoproteome of alpha cells, beta cells, and compound-treated alpha cells. Our phosphoproteomic analysis indicated that two kinases, BRSK1 and CAMKK2, exhibit decreased phosphorylation in beta cells compared to alpha cells, and in compound-treated alpha cells compared to DMSO-treated alpha cells. Knock-down of these kinases in alpha cells resulted in expression of key beta-cell markers. These results provide evidence that perturbation of the kinome may be important for lineage reprogramming of alpha cells to beta cells. PMID:24759943

  15. Distinct glucose lowering and beta cell protective effects of vanadium and food restriction in streptozotocin-diabetes.

    PubMed

    Cam, M C; Rodrigues, B; McNeill, J H

    1999-11-01

    Vanadium is an oral insulin-mimetic agent that diminishes hyperglycemia, improves beta-cell insulin store and secretory function, and can reverse the diabetic state chronically after withdrawal from treatment. As food restriction has been reported to enhance insulin sensitivity and reduce insulin demand, we assessed the contribution of a reduced food intake to the glucose lowering and beta-cell protective effects of vanadium. Streptozotocin (STZ)-diabetic rats were untreated (D) or administered vanadyl sulfate in the drinking water (DT) at one week prior to and for 5 weeks following the administration of STZ. An additional group was pair-fed (DP) with an equal amount of food as that consumed by the DT group. Shortly after the induction of diabetes, hyperglycemic D rats demonstrated a significant rise in plasma insulin to levels that initially exceeded that of the controls. This was followed by a steady reduction over several weeks, suggesting a gradual depletion of functional beta-cells. Both vanadium treatment and pair-feeding abolished the insulin hypersecretory response following STZ administration. Glucose lowering was enhanced in DT animals when administered higher concentrations of vanadium, despite no further reduction in food intake, and all DT animals (10/10) were normoglycemic by 5 weeks. Mean pancreatic insulin content in DT rats was improved fourfold and was associated with a greater number of granulated beta-cells. Conversely, food restriction only modestly improved glycemia and the pancreatic insulin store and, unlike DT, DP rats remained highly glucose-intolerant. At 5 weeks of diabetes, fed circulating glucose and insulin levels were strongly correlated (P=0.0002) in the D and DP groups, supporting the notion that glucose lowering with food restriction is dependent on improved plasma insulin levels. A separate correlation was observed in DT animals within a lower range of plasma insulin, suggesting that vanadium, unlike food restriction, reduced

  16. Protective effect of a microtubule stabilizer taxol on caerulein-induced acute pancreatitis in rat.

    PubMed Central

    Ueda, T; Takeyama, Y; Kaneda, K; Adachi, M; Ohyanagi, H; Saitoh, Y

    1992-01-01

    The effect of taxol, which is a microtubule stabilizer, was examined in a model of acute edematous pancreatitis induced in rat by the administration of caerulein. Prophylactic administration of taxol ameliorated inhibition of pancreatic secretion, increased level of serum amylase, pancreatic edema, and histological alterations in this model. Immunofluorescence studies revealed that taxol stabilized the arrangement of microtubules by the action of promoting tubulin polymerization and prevented inhibition of pancreatic digestive enzyme secretion. In isolated rat pancreatic acini, taxol reversed the inhibition of amylase secretion induced by supramaximal concentrations of cholecystokinin octapeptide and did not affect the binding of cholecystokinin octapeptide to its receptor. The results obtained in this study suggest that microtubule disorganization is the initiating event in caerulein-induced pancreatitis and that the inhibition of pancreatic digestive enzyme secretion by interfering with intracellular vesicular transport due to microtubule disorganization causes caerulein-induced pancreatitis. Images PMID:1370296

  17. Role of microRNAs in islet beta-cell compensation and failure during diabetes.

    PubMed

    Plaisance, Valérie; Waeber, Gérard; Regazzi, Romano; Abderrahmani, Amar

    2014-01-01

    Pancreatic beta-cell function and mass are markedly adaptive to compensate for the changes in insulin requirement observed during several situations such as pregnancy, obesity, glucocorticoids excess, or administration. This requires a beta-cell compensation which is achieved through a gain of beta-cell mass and function. Elucidating the physiological mechanisms that promote functional beta-cell mass expansion and that protect cells against death, is a key therapeutic target for diabetes. In this respect, several recent studies have emphasized the instrumental role of microRNAs in the control of beta-cell function. MicroRNAs are negative regulators of gene expression, and are pivotal for the control of beta-cell proliferation, function, and survival. On the one hand, changes in specific microRNA levels have been associated with beta-cell compensation and are triggered by hormones or bioactive peptides that promote beta-cell survival and function. Conversely, modifications in the expression of other specific microRNAs contribute to beta-cell dysfunction and death elicited by diabetogenic factors including, cytokines, chronic hyperlipidemia, hyperglycemia, and oxidized LDL. This review underlines the importance of targeting the microRNA network for future innovative therapies aiming at preventing the beta-cell decline in diabetes. PMID:24734255

  18. Role of MicroRNAs in Islet Beta-Cell Compensation and Failure during Diabetes

    PubMed Central

    Plaisance, Valérie; Waeber, Gérard

    2014-01-01

    Pancreatic beta-cell function and mass are markedly adaptive to compensate for the changes in insulin requirement observed during several situations such as pregnancy, obesity, glucocorticoids excess, or administration. This requires a beta-cell compensation which is achieved through a gain of beta-cell mass and function. Elucidating the physiological mechanisms that promote functional beta-cell mass expansion and that protect cells against death, is a key therapeutic target for diabetes. In this respect, several recent studies have emphasized the instrumental role of microRNAs in the control of beta-cell function. MicroRNAs are negative regulators of gene expression, and are pivotal for the control of beta-cell proliferation, function, and survival. On the one hand, changes in specific microRNA levels have been associated with beta-cell compensation and are triggered by hormones or bioactive peptides that promote beta-cell survival and function. Conversely, modifications in the expression of other specific microRNAs contribute to beta-cell dysfunction and death elicited by diabetogenic factors including, cytokines, chronic hyperlipidemia, hyperglycemia, and oxidized LDL. This review underlines the importance of targeting the microRNA network for future innovative therapies aiming at preventing the beta-cell decline in diabetes. PMID:24734255

  19. Effects of Local Pancreatic Renin-Angiotensin System on the Microcirculation of Rat with Severe Acute Pancreatitis

    PubMed Central

    Feng, Ling; Long, Haocheng; Wang, Hui; Feng, Jiarui; Chen, Feixiang

    2015-01-01

    Severe acute pancreatitis (SAP) is normally related to multiorgan dysfunction and local complications. Studies have found that local pancreatic renin-angiotensin system (RAS) was significantly upregulated in drug-induced SAP. The present study aimed to investigate the effects of angiotensin II receptors inhibitor valsartan on dual role of RAS in SAP in a rat model and to elucidate the underlying mechanisms. 3.8% sodium taurocholate (1 ml/kg) was injected to the pancreatic capsule in order for pancreatitis induction. Rats in the sham group were injected with normal saline in identical locations. We also investigated the regulation of experimentally induced SAP on local RAS expression in the pancreas through determination of the activities of serum amylase, lipase and myeloperoxidase, histological and biochemical analysis, radioimmunoassay, fluorescence quantitative PCR and Western blot analysis. The results indicated that valsartan could effectively suppress the local RAS to protect against experimental acute pancreatitis through inhibition of microcirculation disturbances and inflammation. The results suggest that pancreatic RAS plays a critical role in the regulation of pancreatic functions and demonstrates application potential as AT1 receptor antagonists. Moreover, other RAS inhibitors could be a new therapeutic target in acute pancreatitis. PMID:26170733

  20. Effects of Local Pancreatic Renin-Angiotensin System on the Microcirculation of Rat with Severe Acute Pancreatitis.

    PubMed

    Pan, Zhijian; Feng, Ling; Long, Haocheng; Wang, Hui; Feng, Jiarui; Chen, Feixiang

    2015-07-01

    Severe acute pancreatitis (SAP) is normally related to multiorgan dysfunction and local complications. Studies have found that local pancreatic renin-angiotensin system (RAS) was significantly upregulated in drug-induced SAP. The present study aimed to investigate the effects of angiotensin II receptors inhibitor valsartan on dual role of RAS in SAP in a rat model and to elucidate the underlying mechanisms. 3.8% sodium taurocholate (1 ml/kg) was injected to the pancreatic capsule in order for pancreatitis induction. Rats in the sham group were injected with normal saline in identical locations. We also investigated the regulation of experimentally induced SAP on local RAS expression in the pancreas through determination of the activities of serum amylase, lipase and myeloperoxidase, histological and biochemical analysis, radioimmunoassay, fluorescence quantitative PCR and Western blot analysis. The results indicated that valsartan could effectively suppress the local RAS to protect against experimental acute pancreatitis through inhibition of microcirculation disturbances and inflammation. The results suggest that pancreatic RAS plays a critical role in the regulation of pancreatic functions and demonstrates application potential as AT1 receptor antagonists. Moreover, other RAS inhibitors could be a new therapeutic target in acute pancreatitis. PMID:26170733

  1. Serum levels of pancreatic stone protein (PSP)/reg1A as an indicator of beta-cell apoptosis suggest an increased apoptosis rate in hepatocyte nuclear factor 1 alpha (HNF1A-MODY) carriers from the third decade of life onward

    PubMed Central

    2012-01-01

    Background Mutations in the transcription factor hepatocyte nuclear factor-1-alpha (HNF1A) result in the commonest type of maturity onset diabetes of the young (MODY). HNF1A-MODY carriers have reduced pancreatic beta cell mass, partially due to an increased rate of apoptosis. To date, it has not been possible to determine when apoptosis is occurring in HNF1A-MODY.We have recently demonstrated that beta cell apoptosis stimulates the expression of the pancreatic stone protein/regenerating (PSP/reg) gene in surviving neighbour cells, and that PSP/reg1A protein is subsequently secreted from these cells. The objective of this study was to determine whether serum levels of PSP/reg1A are elevated during disease progression in HNF1A-MODY carriers, and whether it may provide information regarding the onset of beta-cell apoptosis. Methods We analysed serum PSP/reg1A levels and correlated with clinical and biochemical parameters in subjects with HNF1A-MODY, glucokinase (GCK-MODY), and type 1 diabetes mellitus. A control group of normoglycaemic subjects was also analysed. Results PSP/reg1A serum levels were significantly elevated in HNF1A-MODY (n = 37) subjects compared to controls (n = 60) (median = 12.50 ng/ml, IQR = 10.61-17.87 ng/ml versus median = 10.72 ng/ml, IQR = 8.94-12.54 ng/ml, p = 0.0008). PSP/reg1A correlated negatively with insulin levels during OGTT, (rho = −0.40, p = 0.02). Interestingly we noted a significant positive correlation of PSP/reg1A with age of the HNF1A-MODY carriers (rho = 0.40 p = 0.02) with an age of 25 years separating carriers with low and high PSP/reg1A levels. Patients with type 1 diabetes mellitus also had elevated serum levels of PSP/reg1A compared to controls, however this was independent of the duration of diabetes. Conclusion Our data suggest that beta cell apoptosis contributes increasingly to the pathophysiology of HNF1A-MODY in patients 25 years and over. PSP/reg1A may be

  2. Pancreatic functions in high salt fed female rats

    PubMed Central

    Lasheen, Noha N

    2015-01-01

    Salt consumption has been increased worldwide and the association of high salt diets with enhanced inflammation and target organ damage was reported. Little data were available about the effect of high salt diet on exocrine function of pancreas, while the relation between high salt intake and insulin sensitivity was controversial. This study was designed to investigate the effect of high salt diet on exocrine and endocrine pancreatic functions, and to elucidate the possible underlying mechanism(s). Twenty adult female Wistar rats were randomly divided into two groups; control group; fed standard rodent diet containing 0.3% NaCl, and high salt fed group; fed 8% NaCl for 8 weeks. On the day of sacrifice, rats were anesthized by i.p. pentobarbitone (40 μg/kg B.W.). Nasoanal length was measured and fasting blood glucose was determined from rat tail. Blood samples were obtained from abdominal aorta for determination of plasma sodium, potassium, amylase, lipase, aldosterone, insulin, transforming growth factor-β (TGF-β1), and interleukin 6 (IL6). Pancreata of both groups were histologically studied. Compared to control group, 8-week high salt fed group showed: significant elevation in body weight, body mass index, Lee index, plasma sodium, TGF-β1 and IL6, however, plasma aldosterone, amylase, lipase, and insulin levels were significantly decreased. A nonsignificant increase in plasma potassium and nonsignificant changes in fasting blood glucose and HOMA-IR were detected between groups. Pancreatic fibrosis was observed in test group. High salt diet for 8 weeks caused pancreatic fibrosis evidenced by decline of both exocrine and endocrine functions of pancreas in Wistar rats. PMID:26216433

  3. Effect of modafinil on pancreatic exocrine secretion in rats. A comparison with adrafinil and related drugs.

    PubMed

    Chariot, J; Appia, F; Vaille, C; Rozé, C

    1987-01-01

    The effects of modafinil and adrafinil, 2 drugs that induce locomotor hyperactivity, and those of the parent compounds CRL 40467 and CRL 40385, were studied on the external pancreatic secretion of anaesthetized and conscious rats. In anaesthetized rats modafinil, adrafinil, and CRL 40385 antagonized the central vagal stimulation of protein output induced by 2-deoxy-D-glucose in the pancreatic juice. In conscious rats, modafinil and adrafinil inhibited the output of protein in the basal interdigestive pancreatic secretion. Modafinil was more active than adrafinil as an inhibitor of pancreatic secretion. The effects of modafinil and adrafinil were different from those of sympathetic amines and dopamine: they did not stimulate the output of bicarbonate in anaesthetized rats, and pancreatic inhibition observed in conscious rats was not inhibited by either yohimbine or prazosin. PMID:2893764

  4. Muscarinic cholinergic receptors in pancreatic acinar carcinoma of rat.

    PubMed

    Taton, G; Delhaye, M; Swillens, S; Morisset, J; Larose, L; Longnecker, D S; Poirier, G G

    1985-04-15

    The active enantiomer of tritiated quinuclidinyl benzilate (3H(-)QNB) was used as a ligand to evaluate the muscarinic receptors. The 3H(-)QNB binding characteristics of muscarinic cholinergic receptors obtained from normal and neoplastic tissues were studied to determine changes in receptor properties during neoplastic transformation. Saturable and stereospecific binding sites for 3H(-)QNB are present in homogenates of rat pancreatic adenocarcinoma. The proportions of high- and low-affinity agonist binding sites are similar for neoplastic and normal tissues. The density of muscarinic receptors is higher in neoplastic (200 femtomoles/mg protein) than in normal pancreatic homogenates (80 femtomoles/mg protein). The muscarinic binding sites of the neoplastic and fetal pancreas show similar KD values which are higher than those observed for normal pancreas. PMID:2580801

  5. Beta-cell mitochondrial carriers and the diabetogenic stress response.

    PubMed

    Brun, Thierry; Maechler, Pierre

    2016-10-01

    Mitochondria play a central role in pancreatic beta-cells by coupling metabolism of the secretagogue glucose to distal events of regulated insulin exocytosis. This process requires transports of both metabolites and nucleotides in and out of the mitochondria. The molecular identification of mitochondrial carriers and their respective contribution to beta-cell function have been uncovered only recently. In type 2 diabetes, mitochondrial dysfunction is an early event and may precipitate beta-cell loss. Under diabetogenic conditions, characterized by glucotoxicity and lipotoxicity, the expression profile of mitochondrial carriers is selectively modified. This review describes the role of mitochondrial carriers in beta-cells and the selective changes in response to glucolipotoxicity. In particular, we discuss the importance of the transfer of metabolites (pyruvate, citrate, malate, and glutamate) and nucleotides (ATP, NADH, NADPH) for beta-cell function and dysfunction. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou. PMID:26979549

  6. Mesobiliverdin IXα Enhances Rat Pancreatic Islet Yield and Function.

    PubMed

    Ito, Taihei; Chen, Dong; Chang, Cheng-Wei Tom; Kenmochi, Takashi; Saito, Tomonori; Suzuki, Satoshi; Takemoto, Jon Y

    2013-01-01

    The aims of this study were to produce mesobiliverdin IXα, an analog of anti-inflammatory biliverdin IXα, and to test its ability to enhance rat pancreatic islet yield for allograft transplantation into diabetic recipients. Mesobiliverdin IXα was synthesized from phycocyanobilin derived from cyanobacteria, and its identity and purity were analyzed by chromatographic and spectroscopic methods. Mesobiliverdin IXα was a substrate for human NADPH biliverdin reductase. Excised Lewis rat pancreata infused with mesobiliverdin IXα and biliverdin IXα-HCl (1-100 μM) yielded islet equivalents as high as 86.7 and 36.5%, respectively, above those from non-treated controls, and the islets showed a high degree of viability based on dithizone staining. When transplanted into livers of streptozotocin-induced diabetic rats, islets from pancreata infused with mesobiliverdin IXα lowered non-fasting blood glucose (BG) levels in 55.6% of the recipients and in 22.2% of control recipients. In intravenous glucose tolerance tests, fasting BG levels of 56 post-operative day recipients with islets from mesobiliverdin IXα infused pancreata were lower than those for controls and showed responses that indicate recovery of insulin-dependent function. In conclusion, mesobiliverdin IXα infusion of pancreata enhanced yields of functional islets capable of reversing insulin dysfunction in diabetic recipients. Since its production is scalable, mesobiliverdin IXα has clinical potential as a protectant of pancreatic islets for allograft transplantation. PMID:23630498

  7. Increased expression of transforming growth factor beta s after acute oedematous pancreatitis in rats suggests a role in pancreatic repair.

    PubMed Central

    Riesle, E; Friess, H; Zhao, L; Wagner, M; Uhl, W; Baczako, K; Gold, L I; Korc, M; Büchler, M W

    1997-01-01

    BACKGROUND: Transforming growth factor beta isoforms (TGF beta s) belong to a family of multifunctional regulators of cellular growth and differentiation. They are mitogenic and chemotactic for fibroblasts and are potent stimulators of extracellular matrix production (collagen) and deposition. Upregulation of TGF beta transcription has been reported for several in vivo systems during repair after injury. AIMS: To study the expression of the three mammalian isoforms of TGF beta (TGF beta 1-3) and their relation to collagen expression as a marker for fibroblast response in acute oedematous pancreatitis in rats. METHODS: Using northern blot analysis and immunohistochemistry, the expression and localisation of TGF beta isoforms, collagen, and amylase were analysed during the course of acute oedematous pancreatitis in rats, experimentally induced by intravenous caerulein infusion. RESULTS: Induction of acute pancreatitis resulted in a biphasic peak pattern of expression of TGF beta 1, beta 2, and beta 3 mRNA, with a pronounced increase from day 1 to day 3 (sixfold, 2.5-fold, fivefold, respectively) and again from day 5 to day 7 (three-fold, 2.3-fold, 3.5-fold, respectively). The temporal changes in TGF beta mRNA identically paralleled the expression in collagen mRNA. In contrast, amylase mRNA expression, used as a general indicator of acinar cell integrity, was slightly decreased after induction of acute pancreatitis. Immunohistochemical analysis of pancreatitis tissue showed that increased expression of TGF beta s was mainly present in the pancreatic acinar and ductal cells; this was evident within one day after pancreatitis induction. CONCLUSION: Overexpression of TGF beta s after induction of acute pancreatitis suggests a role for these proteins in pancreatic repair and remodelling. The increased levels of TGF beta s may help suppress immune activation, and may contribute to the increase in the extracellular matrix including collagen and to the repair of the

  8. Comparative effects of Citrullus colocynthis, sunflower and olive oil-enriched diet in streptozotocin-induced diabetes in rats.

    PubMed

    Sebbagh, N; Cruciani-Guglielmacci, C; Ouali, F; Berthault, M-F; Rouch, C; Sari, D Chabane; Magnan, C

    2009-06-01

    Citrullus colocynthis (colocynth) seeds are traditionally used as antidiabetic medication in Mediterranean countries. The present study evaluated the differential effects of diets enriched with C. colocynthis, sunflower or olive oils on the pancreatic beta-cell mass in streptozotocin (STZ)-induced diabetes in rats. STZ injection induced rapid hyperglycaemia in all animals. However, 2 months later, hyperglycaemia was significantly less pronounced in the rats fed a C. colocynthis oil-enriched diet compared with other rat groups (7.9mM versus 12mM and 16mM with colocynth versus olive and sunflower oils, respectively). Assessment of insulin sensitivity using the homoeostasis model assessment (HOMA) method also indicated less insulin resistance in the rats fed a C. colocynthis oil-enriched diet versus the other rats. Finally, 2 months after STZ injection, the pancreatic beta-cell mass was similar in both the STZ-treated rats fed the colocynth oil-enriched diet and their controls fed the same diet. In contrast, the pancreatic beta-cell mass remained lower in the STZ-induced diabetic rats fed with olive oil- and sunflower oil-enriched diets compared with the C. colocynthis group. We conclude that C. colocynthis oil supplementation may have a beneficial effect by partly preserving or restoring pancreatic beta-cell mass in the STZ-induced diabetes rat model. PMID:19264524

  9. Time course and cellular source of pancreatic regeneration following acute pancreatitis in the rat

    SciTech Connect

    Elsaesser, H.P.A.; Adler, G.; Kern, H.F.

    1986-01-01

    The regenerative capacity of the different cell types in the rat exocrine pancreas has been studied in a model of hormone-induced acute pancreatitis in which pancreatic edema, inflammation, and acinar cell destruction were induced within 12 h of infusion of supramaximal concentrations of cerulein (5 micrograms/kg/h). A sequential biochemical and structural analysis of the pancreas in daily intervals was combined with the autoradiographic quantitation of labeling indices of five cell populations following /sup 3/H-thymidine injection at days 1-7 after induction of pancreatitis. Desquamation of acinar cell apical cytoplasm and release of cytoplasmic segments into the acinar lumen on the first day following induction of pancreatitis led to formation of duct-like tubular complexes. Enzyme content in the pancreas decreased progressively following the formation of the edema to levels 15-20% of controls and remained reduced during the initial 5 days. Thymidine incorporation into total DNA showed a biphasic pattern with a distinct peak at day 1 and a second broader peak between days 4 and 7. Autoradiographic quantitation of labeling indices demonstrated the exclusive incorporation into intercalated duct cells and interstitial cells during the initial 24 h, while the second peak was predominantly due to labeling of acinar cells. Larger interlobular ducts and islets did not show changes in labeling index. In vivo labeling with /sup 3/H-thymidine during the first day and analysis of labeling indices 14 days later showed the persistence of label in intercalated duct cells and interstitial cells and argued against the stem cell hypothesis and against transformation of duct cells into acinar cells.

  10. Metabonomic changes from pancreatic intraepithelial neoplasia to pancreatic ductal adenocarcinoma in tissues from rats.

    PubMed

    Wen, Shi; Li, Zhishui; Feng, Jianghua; Bai, Jianxi; Lin, Xianchao; Huang, Heguang

    2016-06-01

    Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumors and is difficult to diagnose in the early phase. This study was aimed at obtaining the metabolic profiles and characteristic metabolites of pancreatic intraepithelial neoplasia (PanIN) and PDAC tissues from Sprague-Dawley (SD) rats to establish metabonomic methods used in the early diagnosis of PDAC. In the present study, the animal models were established by embedding 7,12-dimethylbenzanthracene (DMBA) in the pancreas of SD rats to obtain PanIN and PDAC tissues. After the preprocessing of tissues, (1) H nuclear magnetic resonance (NMR) spectroscopy combined with multivariate and univariate statistical analysis was applied to identify the potential metabolic signatures and the corresponding metabolic pathways. Pattern recognition models were successfully established and differential metabolites, including glucose, amino acids, carboxylic acids and coenzymes, were screened out. Compared with the control, the trends in the variation of several metabolites were similar in both PanIN and PDAC. Kynurenate and methionine levels were elevated in PanIN but decreased in PDAC, thus, could served as biomarkers to distinguish PanIN from PDAC. Our results suggest that NMR-based techniques combined with multivariate statistical analysis can distinguish the metabolic differences among PanIN, PDAC and normal tissues, and, therefore, present a promising approach for physiopathologic metabolism investigations and early diagnoses of PDAC. PMID:27019331

  11. IL-13 improves beta-cell survival and protects against IL-1beta-induced beta-cell death

    PubMed Central

    Rütti, Sabine; Howald, Cédric; Arous, Caroline; Dermitzakis, Emmanouil; Halban, Philippe A.; Bouzakri, Karim

    2015-01-01

    Objectives IL-13 is a cytokine classically produced by anti-inflammatory T-helper-2 lymphocytes; it is decreased in the circulation of type 2 diabetic patients and impacts positively on liver and skeletal muscle. Although IL-13 can exert positive effects on beta-cell lines, its impact and mode of action on primary beta-cell function and survival remain largely unexplored. Methods Beta-cells were cultured for 48 h in the presence of IL-13 alone or in combination with IL-1β or cytokine cocktail (IL-1β, IFNγ, TNFα). Results IL-13 protected human and rat beta-cells against cytokine induced death. However, IL-13 was unable to protect from IL-1β impaired glucose stimulated insulin secretion and did not influence NFκB nuclear relocalization induced by IL-1β. IL-13 induced phosphorylation of Akt, increased IRS2 protein expression and counteracted the IL-1β induced regulation of several beta-cell stress response genes. Conclusions The prosurvival effects of IL-13 thus appear to be mediated through IRS2/Akt signaling with NFκB independent regulation of gene expression. In addition to previously documented beneficial effects on insulin target tissues, these data suggest that IL-13 may be useful for treatment of type 2 diabetes by preserving beta-cell mass or slowing its rate of decline. PMID:26909320

  12. Minireview: beta-cell replacement therapy for diabetes in the 21st century: manipulation of cell fate by directed differentiation.

    PubMed

    Yechoor, Vijay; Chan, Lawrence

    2010-08-01

    Pancreatic beta-cell failure underlies type 1 diabetes; it also contributes in an essential way to type 2 diabetes. beta-Cell replacement is an important component of any cure for diabetes. The current options of islet and pancreas transplantation are not satisfactory as definitive forms of therapy. Here, we review strategies for induced de novo pancreatic beta-cell formation, which depend on the targeted differentiation of cells into pancreatic beta-cells. With this objective in mind, one can manipulate the fate of three different types of cells: 1) from terminally differentiated cells, e.g. exocrine pancreatic cells, into beta-cells; 2) from multipotent adult stem cells, e.g. hepatic oval cells, into pancreatic islets; and 3) from pluripotent stem cells, e.g. embryonic stem cells and induced pluripotent stem cells, into beta-cells. We will examine the pros and cons of each strategy as well as the hurdles that must be overcome before these approaches to generate new beta-cells will be ready for clinical application. PMID:20219891

  13. Genetic predisposition for beta cell fragility underlies type 1 and type 2 diabetes.

    PubMed

    Dooley, James; Tian, Lei; Schonefeldt, Susann; Delghingaro-Augusto, Viviane; Garcia-Perez, Josselyn E; Pasciuto, Emanuela; Di Marino, Daniele; Carr, Edward J; Oskolkov, Nikolay; Lyssenko, Valeriya; Franckaert, Dean; Lagou, Vasiliki; Overbergh, Lut; Vandenbussche, Jonathan; Allemeersch, Joke; Chabot-Roy, Genevieve; Dahlstrom, Jane E; Laybutt, D Ross; Petrovsky, Nikolai; Socha, Luis; Gevaert, Kris; Jetten, Anton M; Lambrechts, Diether; Linterman, Michelle A; Goodnow, Chris C; Nolan, Christopher J; Lesage, Sylvie; Schlenner, Susan M; Liston, Adrian

    2016-05-01

    Type 1 (T1D) and type 2 (T2D) diabetes share pathophysiological characteristics, yet mechanistic links have remained elusive. T1D results from autoimmune destruction of pancreatic beta cells, whereas beta cell failure in T2D is delayed and progressive. Here we find a new genetic component of diabetes susceptibility in T1D non-obese diabetic (NOD) mice, identifying immune-independent beta cell fragility. Genetic variation in Xrcc4 and Glis3 alters the response of NOD beta cells to unfolded protein stress, enhancing the apoptotic and senescent fates. The same transcriptional relationships were observed in human islets, demonstrating the role of beta cell fragility in genetic predisposition to diabetes. PMID:26998692

  14. Chronic stress sensitizes rats to pancreatitis induced by cerulein: Role of TNF-α

    PubMed Central

    Binker, Marcelo G; Binker-Cosen, Andres A; Richards, Daniel; Gaisano, Herbert Y; de Cosen, Rodica H; Cosen-Binker, Laura I

    2010-01-01

    AIM: To investigate chronic stress as a susceptibility factor for developing pancreatitis, as well as tumor necrosis factor-α (TNF-α) as a putative sensitizer. METHODS: Rat pancreatic acini were used to analyze the influence of TNF-α on submaximal (50 pmol/L) cholecystokinin (CCK) stimulation. Chronic restraint (4 h every day for 21 d) was used to evaluate the effects of submaximal (0.2 μg/kg per hour) cerulein stimulation on chronically stressed rats. RESULTS: In vitro exposure of pancreatic acini to TNF-α disorganized the actin cytoskeleton. This was further increased by TNF-α/CCK treatment, which additionally reduced amylase secretion, and increased trypsin and nuclear factor-κB activities in a protein-kinase-C δ and ε-dependent manner. TNF-α/CCK also enhanced caspases’ activity and lactate dehydrogenase release, induced ATP loss, and augmented the ADP/ATP ratio. In vivo, rats under chronic restraint exhibited elevated serum and pancreatic TNF-α levels. Serum, pancreatic, and lung inflammatory parameters, as well as caspases’activity in pancreatic and lung tissue, were substantially enhanced in stressed/cerulein-treated rats, which also experienced tissues’ ATP loss and greater ADP/ATP ratios. Histological examination revealed that stressed/cerulein-treated animals developed abundant pancreatic and lung edema, hemorrhage and leukocyte infiltrate, and pancreatic necrosis. Pancreatitis severity was greatly decreased by treating animals with an anti-TNF-α-antibody, which diminished all inflammatory parameters, histopathological scores, and apoptotic/necrotic markers in stressed/cerulein-treated rats. CONCLUSION: In rats, chronic stress increases susceptibility for developing pancreatitis, which involves TNF-α sensitization of pancreatic acinar cells to undergo injury by physiological cerulein stimulation. PMID:21105189

  15. Developmental patterns for pancreatic opioids in the rat.

    PubMed

    Powell, A M; Voyles, N R; Wilkins, S D; Zalenski, C M; Timmers, K I; Recant, L

    1989-01-01

    Developmental patterns for rat pancreatic opioid peptides and islet hormones were studied from gestational day 20 through adulthood. Fetal tissue was obtained as well as pancreas at birth (day 0), and postnatal days 3, 7, 14, and 21, and 7 weeks. The hormones measured included insulin, glucagon, and somatostatin. The opioids measured were beta-endorphin, Met- and Leu-enkephalins, and the high molecular weight enkephalin precursors. Pancreata were pooled as necessary and extracted (acid alcohol, or hot acetic acid), and opioids were further purified on reversed-phase C-18 (Sep-pak) cartridges. In all instances measurements were made by radioimmunoassays. Precursor peptides were first digested (with trypsin and carboxypeptidase B) prior to immunoassay. All opioids and hormones except the precursors for enkephalins showed a well-defined surge in pancreatic concentration during the first postnatal week. In contrast, the precursors had the highest concentration in the fetus, and by the seventh day of life had decreased by greater than 50%. This progressive decrease may represent maturation of the enkephalin convertase and trypsin-like enzymes in the islets. The opioid and hormonal surges that we have described are similar to the surge in islet concentration of thyroid-releasing hormone (TRH) previously described in neonatal rat islets. It is suggested that these postnatal alterations in opioid and hormone concentration relate to a specific function in the development of the endocrine pancreas. PMID:2530576

  16. Beta-cell preservation…Is weight loss the answer?

    PubMed

    Mazza, Angela D; Pratley, Richard E; Smith, Steven R

    2011-01-01

    Obesity is associated with an increased risk of type 2 diabetes (T2D). Pancreatic beta-cell failure is an early event in the development of glucose dysregulation and diabetes. Interventions to halt beta-cell failure in T2D include diet modification, exercise, and use of pharmacologic agents. There is evidence that abdominal obesity may contribute to diabetes through insulin resistance and beta-cell impairment. Pivotal long-term studies into the prevention of T2D have shown the importance of weight loss beside diet, lifestyle, and medication. The Finnish Diabetes Prevention Program (DPP) showed that weight loss gradually reduces the risk of diabetes, and that even modest weight loss can significantly reduce the incidence of T2D. Similarly, in the US DPP, weight loss as part of intensive lifestyle modification was the major factor in reducing the incidence of T2D in high-risk subjects, being more effective than drug intervention. While understanding the relationship between obesity and diabetes is complex, we know that weight loss has positive effects on adipose tissue. It causes an increase in the beneficial fat cell hormone adiponectin, and a decrease in adipose tissue inflammation. Also, it is associated with reduced insulin resistance and a consequential reduction in glucolipotoxicity, which can improve beta-cell function. In summary, weight loss improves glycemic control and thereby mitigates diabetes symptoms and complications, possibly through the preservation of beta-cell function. Therefore, efforts to prevent diabetes and preserve beta-cell function in patients with T2D should more consequently emphasize and target weight loss. PMID:22580726

  17. Ascorbic acid recycling by cultured beta cells: effects of increased glucose metabolism.

    PubMed

    Steffner, Robert J; Wu, Lan; Powers, Alvin C; May, James M

    2004-11-15

    Ascorbic acid is necessary for optimal insulin secretion from pancreatic islets. We evaluated ascorbate recycling and whether it is impaired by increased glucose metabolism in the rat beta-cell line INS-1. INS-1 cells, engineered with the potential for overexpression of glucokinase under the control of a tetracycline-inducible gene expression system, took up and reduced dehydroascorbic acid to ascorbate in a concentration-dependent manner that was optimal in the presence of physiologic D-glucose concentrations. Ascorbate uptake did not affect intracellular GSH concentrations. Whereas depletion of GSH in culture to levels about 25% of normal also did not affect the ability of the cells to reduce dehydroascorbic acid, more severe acute GSH depletion to less than 10% of normal levels did impair dehydroascorbic acid reduction. Culture of inducible cells in 11.8 mM D-glucose and doxycycline for 48 h enhanced glucokinase activity, increased glucose utilization, abolished D-glucose-dependent insulin secretion, and increased generation of reactive oxygen species. The latter may have contributed to subsequent decreases in the ability of the cells both to maintain intracellular ascorbate and to recycle it from dehydroascorbic acid. Cultured beta cells have a high capacity to recycle ascorbate, but this is sensitive to oxidant stress generated by increased glucose metabolism due to culture in high glucose concentrations and increased glucokinase expression. Impaired ascorbate recycling as a result of increased glucose metabolism may have implications for the role of ascorbate in insulin secretion in diabetes mellitus and may partially explain glucose toxicity in beta cells. PMID:15477012

  18. Impaired pancreatic duct-cell growth in focal areas of regeneration after partial pancreatectomy in the adult Goto-Kakizaki rat, a spontaneous model of non-insulin dependent diabetes mellitus.

    PubMed

    Plachot, C; Portha, B

    2001-03-01

    The Paris colony of adult Goto-Kakizaki (GK/Par) rat, a genetic model of non-insulin dependent diabetes mellitus, is characterized by a restriction of the beta-cell mass and reduced beta-cell regeneration capacity. In order to have a better understanding of the impaired mechanism(s) leading to reduced beta-cell plasticity in the GK/Par rat, we have investigated duct-cell growth capacity following 90% pancreatectomy, a well-defined procedure leading in non-diabetic rats, to sequential duct proliferation and subsequent differentiation. To this aim, we have performed pancreatectomy in 8-10-week-old male normoglycaemic Wistar and diabetic GK rats. Duct-cell proliferation and apoptosis were evaluated at different time points: day 0 (D0), day 2 (D2), day 7 (D7) and day 14 (D14) after pancreatectomy. A transient wave of duct-cell proliferation was observed on D2 in both small and main ducts in the pancreatectomized Wistar rats. A similar increase occurred in the similarly treated GK rats, but to a higher extent as compared to the Wistar rats. Thereafter, duct-cell proliferation from main or small ducts returned to non-pancreatectomized values on D7 and remained at this level on D14 in both the Wistar and GK pancreatectomized groups. In the common pancreatic duct, the number of proliferative duct-cells was higher in GK rats compared to Wistar on D0. In both the operated Wistar and GK rats, duct-cell proliferation from the common pancreatic duct similarly decreased on D2. On D7 and D14, the same parameter returned to non-pancreatectomized values in the Wistar rats, while it was maintained lower in the GK rats as compared to the GK values on D0. In focal areas of regeneration, duct-cell proliferation was significantly lower in the pancreatectomized GK group compared to the age-related Wistar group on D7 (Wistar: 5.85+/-0.98%, GK: 3.02+/-0.69%; p < 0.01) and D14 (Wistar: 3.82+/-0.29%, GK: 2.62+/-0.27%; ns). Only a few apoptotic duct-cells were observed, with no difference

  19. Oxidative stress increases the risk of pancreatic β cell damage in chronic renal hypertensive rats.

    PubMed

    Gao, Shan; Park, Byung M; Cha, Seung A; Bae, Ui J; Park, Byung H; Park, Woo H; Kim, Suhn H

    2016-08-01

    Hypertension often occurs in conjunction with insulin resistance. The purpose of this study was to evaluate whether sustained renal hypertension increases the risk of diabetes mellitus in rats, and to define the underlying mechanisms. Two-kidney, one-clip hypertensive (2K1C) rats received captopril (50 mg/kg/day), α-lipoic acid (100 mg/kg/day), or vehicle treatment for 3 months after surgery. Blood pressure was measured by tail cuff plethysmography. Oral glucose tolerance test (OGTT), immunohistochemistry, and western blotting were performed. In addition, insulin secretion from islet cells was measured. OGTT yielded abnormal results, and the number of islet cells and the size of pancreatic β/α cells were decreased in 2K1C rats. Basal insulin levels were also reduced in the plasma. Insulin secretion from pancreatic islet cells in response to high glucose was also attenuated in 2K1C rats compared with sham rats. The levels of oxidative stress markers, including 8-hydroxydeoxyguanosine and NADPH oxidase-4, were increased in pancreatic tissue and pancreatic islets in 2K1C rats. The abnormalities observed in 2K1C rats were improved by captopril or α-lipoic acid treatment. These findings indicate that sustained renal hypertension may lead to pancreatic dysfunction, increasing oxidative stress in pancreatic islets. PMID:27535482

  20. Effect of Phyllanthus amarus on serum biochemical changes in azaserine induced pancreatic cancer in Wistar rats

    PubMed Central

    Prajapati, Ankit S.; Raval, Sunant K.; Sinha, Suprita; Varia, Tapan N.; Mashiyava, Parimal H.

    2015-01-01

    Aim: The present study was performed to investigate the effect of Phyllanthus amarus extracts on serum biochemical changes in azaserine induced pancreatic cancer in Wistar rats. Materials and Methods: Pancreatic cancer was developed in Wistar rats by intraperitoneal administration of azaserine (cancer inducer) for 21 days at the concentration of 5 mg/kg body weight. Aqueous and alcoholic extracts were given to rats of different groups as per protocol. Results: The results data revealed that oral administration of P. amarus extracts had a significant change in pancreatic amylase, lipase, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activity. Conclusion: We concluded that extract of P. amarus possessed chemoprotective activity against azaserine induced pancreatic cancer in Wistar rats. PMID:27047180

  1. Sensitivity of rat pancreatic A and B cells to somatostatin.

    PubMed

    Schuit, F C; Derde, M P; Pipeleers, D G

    1989-03-01

    Islet A and B cells were purified from the rat pancreas and examined for their respective sensitivity to somatostatin. Both somatostatin-14 (S14) and -28 (S28) inhibited glucagon and insulin release through direct interactions with the corresponding cell types. A dose-dependent suppression of the secretory activities was paralleled by a reduction in cellular cyclic AMP formation with similar ED50 values for both actions. The somatostatin effects on pancreatic hormone release may thus be mediated via an inhibition of adenylate cyclase activity. In pancreatic A cells, S14 and S28 were equally potent inhibitors with ED50 values ranging from 2 x 10(-12) to 2 x 10(-11) mol/l. Pancreatic B cells exhibited a similar sensitivity to S28 as the A cells (ED50 of 2 to 5 x 10(-11) mol/l), but not to S14 (ED50 of 2 x 10(-9) mol/l). Extrapolation of these in vitro sensitivities of islet A and B cells to the in vivo situation suggests that both cell types can respond to circulating S28 levels and that A cells are sensitive to both locally and distally released S14. Islet B cells appear insensitive to the normal peripheral S14 levels but could respond to locally released somatostatin. The marked difference in the sensitivities of islet A and B cells to S14 suggest that these cell types are equipped with different somatostatin receptors. This notion was further supported by the cell-selective actions of the synthetic S14 analogues [D-Trp8, D-Cys14]S14 and desAsn5[D-Trp8, D-Ser13]S14. PMID:2568961

  2. A Simple Matter of Life and Death—The Trials of Postnatal Beta-Cell Mass Regulation

    PubMed Central

    Tarabra, Elena; Pelengaris, Stella; Khan, Michael

    2012-01-01

    Pancreatic beta-cells, which secrete the hormone insulin, are the key arbiters of glucose homeostasis. Defective beta-cell numbers and/or function underlie essentially all major forms of diabetes and must be restored if diabetes is to be cured. Thus, the identification of the molecular regulators of beta-cell mass and a better understanding of the processes of beta-cell differentiation and proliferation may provide further insight for the development of new therapeutic targets for diabetes. This review will focus on the principal hormones and nutrients, as well as downstream signalling pathways regulating beta-cell mass in the adult. Furthermore, we will also address more recently appreciated regulators of beta-cell mass, such as microRNAs. PMID:22577380

  3. Regulation of. beta. -cell glucose transporter gene expression

    SciTech Connect

    Chen, Ling; Alam, Tausif; Johnson, J.H.; Unger, R.H. Department of Veterans Affairs Medical Center, Dallas, TX ); Hughes, S.; Newgard, C.B. )

    1990-06-01

    It has been postulated that a glucose transporter of {beta} cells (GLUT-2) may be important in glucose-stimulated insulin secretion. To determine whether this transporter is constitutively expressed or regulated, the authors subjected conscious unrestrained Wistar rats to perturbations in glucose homeostasis and quantitated {beta}-cell GLUT-2 mRNA by in situ hybridization. After 3 hr of hypoglycemia, GLUT-2 and proinsulin mRNA signal densities were reduced by 25% of the level in control rats. After 4 days, GLUT-2 and proinsulin mRNA densities were reduced by 85% and 65%, respectively. After 12 days of hypoglycemia, the K{sub m} for 3-O-methyl-D-glucose transport in isolated rat islets, normally 18-20 mM, was 2.5 mM. This provides functional evidence of a profound reduction of high K{sub m} glucose transporter in {beta} cells. In contrast, GLUT-2 was only slightly reduced by hypoglycemia in liver. To determine the effect of prolonged hyperglycemia, they also infused animals with 50% (wt/vol) glucose for 5 days. Hyperglycemic clamping increased GLUT-2 mRNA by 46% whereas proinsulin mRNA doubled. They conclude that GLUT-2 expression in {beta} cells, but not liver, is subject to regulation by certain perturbations in blood glucose homeostasis.

  4. Role of pancreatic enzymes and their substrates in autodigestion of the pancreas. In vitro studies with isolated rat pancreatic acini.

    PubMed

    Nagai, H; Henrich, H; Wünsch, P H; Fischbach, W; Mössner, J

    1989-03-01

    Intrapancreatic activation of proteases is believed to play a major role in the pathogenesis of acute necrotizing pancreatitis. Several authors have questioned, however, the central role of trypsin in autodigestion of the pancreas. To clarify the direct effects of pancreatic enzymes and other related factors on acinar cells, we used the model of isolated pancreatic acini. Acini were prepared from male Wistar rats by collagenase digestion. Protein synthesis was measured by incubation of acini with [35S]methionine. Acini were resuspended thereafter in fresh buffer and further incubated for 30-90 min under various conditions [e.g., with pancreatic homogenates, ascites (from rats with pancreatitis induced by sodium taurocholate), pure pancreatic enzymes, and other factors]. The percentage of release of newly synthesized proteins into the culture medium was regarded as a biochemical parameter of cellular integrity. A morphologic score of cellular integrity was obtained via light microscopic evaluation of acini at the end of the various incubations by measuring the degree of cell lysis, loss of cell granules, ballooning, formation of vacuoles, and karyopyknosis. When normal [35S]methionine-labeled pancreatic acini were incubated with various factors, the percentage of release of labeled proteins into the medium was as follows: incubation with HEPES/Ringer's buffer, 1.8%; hemorrhagic pancreatic ascites, 3.8%; pancreatic homogenates, 2.0%; lipase, 1.8%; phospholipase A2, 3.0%; phospholipase A2 + lecithin, 3.2%; trypsin, 2.5%; 5% olive oil, 1.8%; ascites + olive oil, 78.3%; ascites + homogenized epididymal fat, 79.9%; lipase + olive oil, 32.0%; pancreatic homogenates + olive oil, 28.0%; diolein, 2.65%; and oleic acid, 62.9%. The cellular release of radiolabeled proteins showed an inverse correlation with cellular integrity as shown by light microscopy. We postulate that interstitial release of degradation products from triglycerides by lipase causes cellular disruption

  5. Functional somatostatin receptors on a rat pancreatic acinar cell line

    SciTech Connect

    Viguerie, N.; Tahiri-Jouti, N.; Esteve, J.P.; Clerc, P.; Logsdon, C.; Svoboda, M.; Susini, C.; Vaysse, N.; Ribet, A. Mount Zion Hospital and Medical Center, San Francisco, CA Universite Libre de Bruxelles, Brussels )

    1988-07-01

    Somatostatin receptors from a rat pancreatic acinar cell line, AR4-2J, were characterized biochemically, structurally, and functionally. Binding of {sup 125}I-(Tyr{sup 11})Somatostatin to AR4-2J cells was saturable, exhibiting a single class of high-affinity binding sites with a maximal binding capacity of 258 {plus minus} 20 fmol/10{sup 6} cells. Somatostatin receptor structure was analyzed by covalently cross-linking {sup 125}I-(Tyr{sup 11})somatostatin to its plasma membrane receptors. Gel electrophoresis and autoradiography of cross-linked proteins revealed a peptide containing the somatostatin receptor. Somatostatin inhibited vasoactive intestinal peptide (VIP)-stimulated adenosine 3{prime},5{prime}-cyclic monophosphate (cAMP) formation in a dose-dependent manner. The concentration of somatostatin that caused half-maximal inhibition of cAMP formation was close to the receptor affinity for somatostatin. Pertussis toxin pretreatment of AR4-2J cells prevented somatostatin inhibition of VIP-stimulated cAMP formation as well as somatostatin binding. The authors conclude that AR4-2J cells exhibit functional somatostatin receptors that retain both specificity and affinity of the pancreatic acinar cell somatostatin receptors and act via the pertussis toxin-sensitive guanine nucleotide-binding protein N{sub i} to inhibit adenylate cyclase.

  6. Parathyroid Hormone-Related Peptide (1-36) Enhances Beta Cell Regeneration and Increases Beta Cell Mass in a Mouse Model of Partial Pancreatectomy

    PubMed Central

    Mozar, Anaïs; Lin, Hugo; Williams, Katoura; Chin, Connie; Li, Rosemary; Kondegowda, Nagesha Guthalu; Stewart, Andrew F.; Garcia-Ocaña, Adolfo; Vasavada, Rupangi Chhaya

    2016-01-01

    Aims/Hypothesis Finding ways to stimulate the regeneration of endogenous pancreatic beta cells is an important goal in the treatment of diabetes. Parathyroid hormone-related protein (PTHrP), the full-length (1–139) and amino-terminal (1–36) peptides, enhance beta cell function, proliferation, and survival. Therefore, we hypothesize that PTHrP(1–36) has the potential to regenerate endogenous beta cells. Methods The partial pancreatectomy (PPx) mouse model of beta cell injury was used to test this hypothesis. Male Balb/c mice underwent either sham-operation or PPx, and were subsequently injected with PTHrP(1–36) (160μg/kg) or vehicle (veh), for 7, 30, or 90 days. The four groups of mice, sham-veh, sham-PTHrP, PPx-veh, and PPx-PTHrP were assessed for PTHrP and receptor expression, and glucose and beta cell homeostasis. Results PTHrP-receptor, but not the ligand, was significantly up-regulated in islets from mice that underwent PPx compared to sham-operated mice. This suggests that exogenous PTHrP could further enhance beta cell regeneration after PPx. PTHrP did not significantly affect body weight, blood glucose, plasma insulin, or insulin sensitivity, in either sham or PPx mice. Glucose tolerance improved in the PPx-PTHrP versus PPx-veh mice only in the early stages of treatment. As hypothesized, there was a significant increase in beta cell proliferation in PPx-PTHrP mice at days 7 and 30; however, this was normalized by day 90, compared to PPx-veh mice. Enhanced beta cell proliferation translated to a marked increase in beta cell mass at day 90, in PPx-PTHrP versus PPx-veh mice. Conclusions PTHrP(1–36) significantly enhances beta cell regeneration through increased beta cell proliferation and beta cell mass after PPx. Future studies will determine the potential of PTHrP to enhance functional beta cell mass in the setting of diabetes. PMID:27391423

  7. Effects of urtica dioica extract on experimental acute pancreatitis model in rats

    PubMed Central

    Yilmaz, Baris; Basar, Ömer; Aktas, Bora; Altinbas, Akif; Ekiz, Fuat; Büyükcam, Fatih; Albayrak, Aynur; Ginis, Zeynep; Öztürk, Gülfer; Coban, Sahin; Ucar, Engin; Kaya, Oskay; Yüksel, Osman; Caner, Sedat; Delibasi, Tuncay

    2014-01-01

    Acute pancreatitis is the acute inflammation of pancreas and peripancreatic tissues, and distant organs are also affected. The aim of this study was to investigate the effect of Urtica dioica extract (UDE) treatment on cerulein induced acute pancreatitis in rats. Twenty-one Wistar Albino rats were divided into three groups: Control, Pancreatitis, and UDE treatment group. In the control group no procedures were performed. In the pancreatitis and treatment groups, pancreatitis was induced with intraperitoneal injection of cerulein, followed by intraperitoneal injection of 1 ml saline (pancreatitis group) and 1 ml 5.2% UDE (treatment group). Pancreatic tissues were examined histopathologically. Pro-inflammatory cytokines (tumor necrosis factor-α), amylase and markers of apoptosis (M30, M65) were also measured in blood samples. Immunohistochemical staining was performed with Caspase-3 antibody. Histopathological findings in the UDE treatment group were less severe than in the pancreatitis group (5.7 vs 11.7, p = 0.010). TNF-α levels were not statistically different between treated and control groups (63.3 vs. 57.2, p = 0.141). UDE treatment was associated with less apoptosis [determined by M30, caspase-3 index (%)], (1.769 vs. 0.288, p = 0.056; 3% vs. 2.2%, p = 0.224; respectively). UDE treatment of pancreatitis merits further study. PMID:24995088

  8. Quantitative trait loci on chromosome 8q24 for pancreatic beta-cell function and 7q11 for insulin sensitivity in obese nondiabetic white and black families: evidence from genome-wide linkage scans in the NHLBI Hypertension Genetic Epidemiology Network (HyperGEN) study.

    PubMed

    An, Ping; Freedman, Barry I; Rich, Stephen S; Mandel, Stephen A; Arnett, Donna K; Myers, Richard H; Chen, Yii-Der I; Hunt, Steven C; Rao, D C

    2006-02-01

    Genome-wide linkage scans were carried out using a multipoint variance components method in white and black families of the NHLBI Hypertension Genetic Epidemiology Network (HyperGEN) study to identify quantitative trait loci (QTLs) for pancreatic beta-cell function and insulin sensitivity estimated through the newly released nonlinear computer version of homeostasis model assessment 2. Participants fasting <8 h, with diagnosed type 2 diabetes, or taking blood glucose or blood lipid-lowering medications were excluded. Both phenotypes were adjusted separately by race and sex for the effects of age, BMI, and field center before linkage scans using 370 microsatellite markers were performed. A total of 685 white families (1,180 sibpairs) and 773 black families (775 sibpairs) were evaluated as well as subsets including 267 obese white families (757 sibpairs) and 427 obese black families (599 sibpairs) identified through tree-linkage analyses using interacting covariates of age, sex, and BMI. For beta-cell function in the obese white families, significant (logarithm of odds [LOD] score >3.6) evidence supporting linkages was detected on chromosome 8q24 at D8S1179 (135 cM, LOD score 4.2, empirical P = 0.002) and at D8S1128 (140 cM, LOD score 3.7, empirical P = 0.003). In addition, two regions supported linkage for insulin sensitivity index in the obese black families on chromosome 7q11 at D7S3046 (79 cM, LOD score 3.0, empirical P = 0.018) and on chromosome 6q26 at D6S1277 (173 cM, LOD score 3.0, empirical P = 0.018). Reducing clinical heterogeneity using obesity data and improved estimates of beta-cell function and insulin sensitivity may have permitted identification of a QTL on chromosome 8q24 for beta-cell function in the presence of estimated insulin resistance and a QTL on chromosome 7q11 for insulin sensitivity. These regions replicate previous reports for type 2 diabetes-associated traits. PMID:16443794

  9. Circadian Transcription from Beta Cell Function to Diabetes Pathophysiology.

    PubMed

    Perelis, Mark; Ramsey, Kathryn Moynihan; Marcheva, Biliana; Bass, Joseph

    2016-08-01

    The mammalian circadian clock plays a central role in the temporal coordination of physiology across the 24-h light-dark cycle. A major function of the clock is to maintain energy constancy in anticipation of alternating periods of fasting and feeding that correspond with sleep and wakefulness. While it has long been recognized that humans exhibit robust variation in glucose tolerance and insulin sensitivity across the sleep-wake cycle, experimental genetic analysis has now revealed that the clock transcription cycle plays an essential role in insulin secretion and metabolic function within pancreatic beta cells. This review addresses how studies of the beta cell clock may elucidate the etiology of subtypes of diabetes associated with circadian and sleep cycle disruption, in addition to more general forms of the disease. PMID:27440914

  10. Pancreatitis

    MedlinePlus

    ... the hormones insulin and glucagon into the bloodstream. Pancreatitis is inflammation of the pancreas. It happens when digestive enzymes start digesting the pancreas itself. Pancreatitis can be acute or chronic. Either form is ...

  11. Pancreatic and extrapancreatic effects of GLP-1.

    PubMed

    Valverde, I; Villanueva-Peñacarrillo, M L; Malaisse, W J

    2002-12-01

    Glucagon-like peptide-1 (GLP-1), an incretin hormone which helps to regulate plasma glucose levels, is considered a potential agent for the treatment of type-2 diabetes mellitus, because of its insulinotropic capacity and insulinomimetic actions. In normal conditions, the beta-cell secretory response to GLP-1 is modulated by the extracellular concentration of D-glucose; however, the recognition of D-glucose by the beta-cell is often impaired in type-2 diabetes, and this could impede the full GLP-1 insulinotropic action. Non-glucidic substrates, such as the dimethyl ester of succinic acid, restore the effect of GLP-1 in the isolated perfused rat pancreas of normal or diabetic rats, in the absence of any other exogenous nutrient; likewise, the dimethyl ester of succinic or L-glutamic acid, and the monomethyl ester of pyruvic acid, potentiate the in vivo beta-cell secretory response to GLP-1 in normal and diabetic rats. Therefore, it was proposed that nutrients susceptible to bypass the site-specific defects of the diabetic beta-cell, could be used to potentiate and/or prolong the insulinotropic action of antidiabetic agents such as GLP-1. In vitro, GLP-1 insulin-like effects on glucose metabolism have been documented in normal and diabetic rat liver, and in rat and human skeletal muscle. In rat and human adipocytes, GLP-1 is lipolytic and/or lipogenic, and also stimulates parameters involved in the glucose metabolism. In liver, muscle and fat, GLP-1 seems to act through specific receptors, apparently different--at least in liver and muscle--in structure or signaling pathway from the pancreatic one. It is proposed that an inositolphosphoglycan might be a second messenger of GLP-1 action in extrapancreatic tissues. PMID:12688638

  12. Prevention of autoimmune recurrence and rejection by adenovirus-mediated CTLA4Ig gene transfer to the pancreatic graft in BB rat.

    PubMed

    Uchikoshi, F; Yang, Z D; Rostami, S; Yokoi, Y; Capocci, P; Barker, C F; Naji, A

    1999-03-01

    Type 1 diabetes is the result of a selective destruction of pancreatic islets by autoreactive T-cells. Therefore, in the context of islet or pancreas transplantation, newly transplanted beta-cells are threatened by both recurrent autoimmune and alloimmune responses in recipients with type 1 diabetes. In the present study, using spontaneously diabetic BB rats, we demonstrate that whereas isolated islets are susceptible to autoimmune recurrence and rejection, pancreaticoduodenal grafts are resistant to these biological processes. This resistance is mediated by lymphohematopoietic cells transplanted with the graft, since inactivation of these passenger cells by irradiation uniformly rendered the pancreaticoduodenal grafts susceptible to recurrent autoimmunity. We further studied the impact of local immunomodulation on autoimmune recurrence and rejection by ex vivo adenovirus-mediated CTLA4Ig gene transfer to pancreaticoduodenal grafts. Syngeneic DR-BB pancreaticoduodenal grafts transduced with AdmCTLA4Ig were rescued from recurrent autoimmunity. In fully histoincompatible LEW-->BB transplants, in which rejection and recurrence should be able to act synergistically, AdmCTLA4Ig transduced LEW-pancreaticoduodenal allografts enjoyed markedly prolonged survival in diabetic BB recipients. In situ reverse transcription-polymerase chain reaction revealed that transferred CTLA4Ig gene was strongly expressed in both endocrine and exocrine tissues on day 3. These results indicate the potential utility of local CD28-B7 costimulatory blockade for prevention of alloimmune and autoimmune destruction of pancreatic grafts in type 1 diabetic hosts. PMID:10078573

  13. glucagon is essential for alpha cell transdifferentiation and beta cell neogenesis

    PubMed Central

    Ye, Lihua; Robertson, Morgan A.; Hesselson, Daniel; Stainier, Didier Y. R.; Anderson, Ryan M.

    2015-01-01

    The interconversion of cell lineages via transdifferentiation is an adaptive mode of tissue regeneration and an appealing therapeutic target. However, its clinical exploitation is contingent upon the discovery of contextual regulators of cell fate acquisition and maintenance. In murine models of diabetes, glucagon-secreting alpha cells transdifferentiate into insulin-secreting beta cells following targeted beta cell depletion, regenerating the form and function of the pancreatic islet. However, the molecular triggers of this mode of regeneration are unknown. Here, using lineage-tracing assays in a transgenic zebrafish model of beta cell ablation, we demonstrate conserved plasticity of alpha cells during islet regeneration. In addition, we show that glucagon expression is upregulated after injury. Through gene knockdown and rescue approaches, we also find that peptides derived from the glucagon gene are necessary for alpha-to-beta cell fate switching. Importantly, whereas beta cell neogenesis was stimulated by glucose, alpha-to-beta cell conversion was not, suggesting that transdifferentiation is not mediated by glucagon/GLP-1 control of hepatic glucose production. Overall, this study supports the hypothesis that alpha cells are an endogenous reservoir of potential new beta cells. It further reveals that glucagon plays an important role in maintaining endocrine cell homeostasis through feedback mechanisms that govern cell fate stability. PMID:25852199

  14. Long-term high-fat diet induces pancreatic injuries via pancreatic microcirculatory disturbances and oxidative stress in rats with hyperlipidemia

    SciTech Connect

    Yan Mingxian; Li Yanqing . E-mail: mx8902@163.com; Meng Min; Ren Hongbo; Kou Yi

    2006-08-18

    Relations between hyperlipidemia and chronic pancreatitis remain unclear. Microcirculatory disturbances and oxidative stress are involved in pathogeneses of a high numbers of diseases. The objective of this study was to induce hyperlipidemia in rats by long-term high-fat diet intake, then investigate the biochemical, microcirculatory, and histological alterations in blood and pancreatic tissues of these animals, and discuss their potential significances. Pancreatic blood flow was detected by intravital microscope; malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were measured in pancreatic tissues for assessment of oxidative stress and {alpha}-smooth muscle actin ({alpha}-SMA) expression was determined by immunohistochemical staining and RT-PCR. The results showed that the velocity of pancreatic microvascular blood flow of rats with hyperlipidemia decreased significantly as compared to control value (p = 0.008). Pancreatic MDA content increased whereas SOD activity decreased in these rats (p = 0.022; p = 0.039, respectively). Histologically, microvesicles in acinar and islet cells, dilated rough endoplasmic reticulum, swollen mitochondrion and modified vascular endothelial cells were observed under light microscope and transmission electron microscope. In addition, {alpha}-SMA expression was up-regulated significantly (p < 0.05). These results suggest that long-term high-fat diet can induce chronic pancreatic injuries which could be considered as 'nonalcoholic fatty pancreatic disease', and pancreatic microcirculatory disturbances and oxidative stress may play an important part in the underlying pathogenesis.

  15. Rap1 promotes multiple pancreatic islet cell functions and signals through mammalian target of rapamycin complex 1 to enhance proliferation.

    PubMed

    Kelly, Patrick; Bailey, Candice L; Fueger, Patrick T; Newgard, Christopher B; Casey, Patrick J; Kimple, Michelle E

    2010-05-21

    Recent studies have implicated Epac2, a guanine-nucleotide exchange factor for the Rap subfamily of monomeric G proteins, as an important regulator of insulin secretion from pancreatic beta-cells. Although the Epac proteins were originally identified as cAMP-responsive activators of Rap1 GTPases, the role of Rap1 in beta-cell biology has not yet been defined. In this study, we examined the direct effects of Rap1 signaling on beta-cell biology. Using the Ins-1 rat insulinoma line, we demonstrate that activated Rap1A, but not related monomeric G proteins, promotes ribosomal protein S6 phosphorylation. Using isolated rat islets, we show that this signaling event is rapamycin-sensitive, indicating that it is mediated by the mammalian target of rapamycin complex 1-p70 S6 kinase pathway, a known growth regulatory pathway. This newly defined beta-cell signaling pathway acts downstream of cAMP, in parallel with the stimulation of cAMP-dependent protein kinase, to drive ribosomal protein S6 phosphorylation. Activated Rap1A promotes glucose-stimulated insulin secretion, islet cell hypertrophy, and islet cell proliferation, the latter exclusively through mammalian target of rapamycin complex 1, suggesting that Rap1 is an important regulator of beta-cell function. This newly defined signaling pathway may yield unique targets for the treatment of beta-cell dysfunction in diabetes. PMID:20339002

  16. Beta Cell Formation in vivo Through Cellular Networking, Integration and Processing (CNIP) in Wild Type Adult Mice.

    PubMed

    Doiron, Bruno; Hu, Wenchao; DeFronzo, Ralph A

    2016-01-01

    Insulin replacement therapy is essential in type 1 diabetic individuals and is required in ~40- 50% of type 2 diabetics during their lifetime. Prior attempts at beta cell regeneration have relied upon pancreatic injury to induce beta cell proliferation, dedifferentiation and activation of the embryonic pathway, or stem cell replacement. We report an alternative method to transform adult non-stem (somatic) cells into pancreatic beta cells. The Cellular Networking, Integration and Processing (CNIP) approach targets cellular mechanisms involved in pancreatic function in the organ's adult state and utilizes a synergistic mechanism that integrates three important levels of cellular regulation to induce beta cell formation: (i) glucose metabolism, (ii) membrane receptor function, and (iii) gene transcription. The aim of the present study was to induce pancreatic beta cell formation in vivo in adult animals without stem cells and without dedifferentiating cells to recapitulate the embryonic pathway as previously published (1-3). Our results employing CNIP demonstrate that: (i) insulin secreting cells can be generated in adult pancreatic tissue in vivo and circumvent the problem of generating endocrine (glucagon and somatostatin) cells that exert deleterious effects on glucose homeostasis, and (ii) longterm normalization of glucose tolerance and insulin secretion can be achieved in a wild type diabetic mouse model. The CNIP cocktail has the potential to be used as a preventative or therapeutic treatment or cure for both type 1 and type 2 diabetes. PMID:26696016

  17. The role of apelin in the modulation of gastric and pancreatic enzymes activity in adult rats.

    PubMed

    Antuschevich, H; Kapica, M; Krawczynska, A; Herman, A; Kato, I; Kuwahara, A; Zabielski, R

    2016-06-01

    Apelin is considered as important gut regulatory peptide ligand of APJ receptor with a potential physiological role in gastrointestinal cytoprotection, regulation of food intake and drinking behavior. Circulating apelin inhibits secretion of pancreatic juice through vagal- cholecystokinin-dependent mechanism and reduces local blood flow. Our study was aimed to determine the effect of fundectomy and intraperitoneal or intragastric administration of apelin-13 on pancreatic and gastric enzymes activities in adult rats. Fundectomy is a surgical removal of stomach fundus - maine site apelin synthesis. Three independent experiments were carried out on Wistar rats. In the first and second experiment apelin-13 was given by intragastric or intraperitoneal way twice a day for 10 days (100 nmol/kg b.w.). Control groups received the physiological saline respectively. In the third experiment the group of rats after fundectomy were used. Fundectomized rats did not receive apelin and the rats from control group were 'sham operated'. At the end of experiment rats were sacrificed and blood from rats was withdrawn for apelin and CCK (cholecystokinin) radioimmunoassay analysis and pancreas and stomach tissues were collected for enzyme activity analyses. Intragastric and intraperitoneal administrations of apelin-13 increased basal plasma CCK level and stimulated gastric and pancreatic enzymes activity in rats. In animals after fundectomy decreased activity of studied enzymes was observed, as well as basal plasma apelin and CCK levels. In conclusion, apelin can effects on CCK release and stimulates some gastric and pancreatic enzymes activity in adult rats while fudectomy suppresses those processes. Changes in the level of pancreatic lipase activity point out that apelin may occurs as a regulator of lipase secretion. PMID:27512001

  18. The effect of hypophysectomy on pancreatic islet hormone and insulin-like growth factor I content and mRNA expression in rat.

    PubMed

    Jevdjovic, Tanja; Maake, Caroline; Zwimpfer, Cornelia; Krey, Gunthild; Eppler, Elisabeth; Zapf, Jürgen; Reinecke, Manfred

    2005-02-01

    The growth arrest after hypophysectomy in rats is mainly due to growth hormone (GH) deficiency because replacement of GH or insulin-like growth factor (IGF) I, the mediator of GH action, leads to resumption of growth despite the lack of other pituitary hormones. Hypophysectomized (hypox) rats have, therefore, often been used to study metabolic consequences of GH deficiency and its effects on tissues concerned with growth. The present study was undertaken to assess the effects of hypophysectomy on the serum and pancreatic levels of the three major islet hormones insulin, glucagon, and somatostatin, as well as on IGF-I. Immunohistochemistry (IHC), in situ hybridization (ISH), radioimmunoassays (RIA), and Northern blot analysis were used to localize and quantify the hormones in the pancreas at the peptide and mRNA levels. IHC showed slightly decreased insulin levels in the beta cells of hypox compared with normal, age-matched rats whereas glucagon in alpha cells and somatostatin in delta cells showed increase. IGF-I, which localized to alpha cells, showed decrease. ISH detected a slightly higher expression of insulin mRNA and markedly stronger signals for glucagon and somatostatin mRNA in the islets of hypox rats. Serum glucose concentrations did not differ between the two groups although serum insulin and C-peptide were lower and serum glucagon was higher in the hypox animals. These changes were accompanied by a more than tenfold drop in serum IGF-I. The pancreatic insulin content per gram of tissue was not significantly different in hypox and normal rats. Pancreatic glucagon and somatostatin per gram of tissue were higher in the hypox animals. The pancreatic IGF-I content of hypox rats was significantly reduced. Northern blot analysis gave a 2.6-, 4.5-, and 2.2-fold increase in pancreatic insulin, glucagon, and somatostatin mRNA levels, respectively, in hypox rats, and a 2.3-fold decrease in IGF-I mRNA levels. Our results show that the fall of serum IGF-I after

  19. No evidence of drug-induced pancreatitis in rats treated with exenatide for 13 weeks

    PubMed Central

    Tatarkiewicz, K; Belanger, P; Gu, G; Parkes, D; Roy, D

    2013-01-01

    Aims The potential association of glucagon-like peptide receptor agonists (GLP-1RAs) with the development of pancreatitis or pancreatic malignancies in patients with diabetes has been suggested. This study evaluated the long-term effects of the GLP-1RA exenatide on pancreatic exocrine structure and function in the Zucker diabetic fatty (ZDF) rat model of type 2 diabetes. Methods Rats received subcutaneous twice-daily injections of 0 (control), 6, 40 and 250 µg/kg/day exenatide for 3 months. Clinical signs, body and pancreas weight, food consumption, HbA1c, fasting serum amylase, lipase, glucose and insulin concentrations were evaluated during treatment and after a 28-day off-drug period to assess the reversibility of any observed effects. Morphometric analysis of pancreatic ductal cell proliferation and apoptosis were performed. Results Plasma exenatide concentrations were several-fold higher than therapeutic levels observed in humans. No exenatide-related effects were observed on clinical signs, lipase concentration, pancreatic weight, pancreatic histology, ductal cell proliferation or apoptosis. Exenatide improved animal survival, physical condition, glucose concentrations and HbA1c, decreased food intake, and increased serum insulin concentration. Total amylase concentrations, although within normal ranges, were slightly higher in exenatide-treated rats; following the off-drug period, total amylase concentrations were comparable in treated and untreated rats. Exenatide-related minimal-to-moderate islet hypertrophy was observed at doses ≥6 µg/kg/day, with dose-related increases in incidence and degree. These changes were still present after the off-drug period. Conclusions Chronic administration of exenatide in ZDF rats resulted in the expected metabolic benefits and improved animal survival, with no adverse effects noted on pancreatic exocrine structure and function. PMID:23163898

  20. Evidence for platelet-activating factor as a late-phase mediator of chronic pancreatitis in the rat.

    PubMed Central

    Zhou, W. G.; Chao, W.; Levine, B. A.; Olson, M. S.

    1990-01-01

    The role of platelet-activating factor (PAF) as a mediator of pancreatic inflammation was examined in the rat pancreatic duct ligation model of obstructive pancreatitis. Pancreatic generation of PAF, as measured by bioassay (ie, platelet [3H]serotonin secretion), was determined at various times after induction of inflammation. Tissue levels of PAF in the normal pancreas averaged 600 +/- 49 pg/g, but PAF was not detectable during the initial 24 hours of pancreatitis, a time when the inflammatory reaction would be considered acute, that is, during the period of maximal serum amylase release and the development of interstitial edema. However a substantial increase in pancreatic PAF levels (12 times control levels) was observed 7 to 14 days after duct ligation during the late-phase response interval similar to the situation characteristic of chronic pancreatitis in which parenchymal atrophy, fibrosis, and pancreatic insufficiency evolve. One week after duct ligation when PAF levels peaked, an evaluation was made of the effects of PAF antagonists (BN52021 and WEB2170) on pancreatic lesions using Evan's blue extravasation, pancreatic myeloperoxidase (MPO) activity, and acid phosphatase activity in peritoneal lavage fluid. BN52021 or WEB2170 treatment was shown to reduce pancreatic damage and inflammation significantly. Long-term in vivo administration of exogenous PAF (20 micrograms/kg/hr for 7 days) exhibited a reduction of [3H]thymidine uptake into and amylase release from pancreatic acini in vitro. Our observations 1) that pancreatic PAF levels increased significantly during the chronic phase of obstructive pancreatitis induced by duct ligation; 2) that inhibition of the action of PAF, through specific receptor antagonism, caused an attenuation of pancreatic lesions; and 3) that chronic administration of PAF resulted in decreased pancreatic regeneration and exocrine function are consistent with a pivotal role for PAF as a late-phase inflammatory mediator in chronic

  1. Sulforaphane protects against cytokine- and streptozotocin-induced {beta}-cell damage by suppressing the NF-{kappa}B pathway

    SciTech Connect

    Song, Mi-Young; Kim, Eun-Kyung; Moon, Woo-Sung; Park, Jin-Woo; Kim, Hyung-Jin; So, Hong-Seob; Park, Raekil; Kwon, Kang-Beom Park, Byung-Hyun

    2009-02-15

    Sulforaphane (SFN) is an indirect antioxidant that protects animal tissues from chemical or biological insults by stimulating the expression of several NF-E2-related factor-2 (Nrf2)-regulated phase 2 enzymes. Treatment of RINm5F insulinoma cells with SFN increases Nrf2 nuclear translocation and expression of phase 2 enzymes. In this study, we investigated whether the activation of Nrf2 by SFN treatment or ectopic overexpression of Nrf2 inhibited cytokine-induced {beta}-cell damage. Treatment of RIN cells with IL-1{beta} and IFN-{gamma} induced {beta}-cell damage through a NF-{kappa}B-dependent signaling pathway. Activation of Nrf2 by treatment with SFN and induction of Nrf2 overexpression by transfection with Nrf2 prevented cytokine toxicity. The mechanism by which Nrf2 activation inhibited NF-{kappa}B-dependent cell death signals appeared to involve the reduction of oxidative stress, as demonstrated by the inhibition of cytokine-induced H{sub 2}O{sub 2} production. The protective effect of SFN was further demonstrated by the restoration of normal insulin secreting responses to glucose in cytokine-treated rat pancreatic islets. Furthermore, pretreatment with SFN blocked the development of type 1 diabetes in streptozotocin-treated mice.

  2. Role of bone marrow cells in the development of pancreatic fibrosis in a rat model of pancreatitis induced by a choline-deficient/ethionine-supplemented diet

    SciTech Connect

    Akita, Shingo; Kubota, Koji; Kobayashi, Akira; Misawa, Ryosuke; Shimizu, Akira; Nakata, Takenari; Yokoyama, Takahide; Takahashi, Masafumi; Miyagawa, Shinichi

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer BMC-derived PSCs play a role in a rat CDE diet-induced pancreatitis model. Black-Right-Pointing-Pointer BMC-derived PSCs contribute mainly to the early stage of pancreatic fibrosis. Black-Right-Pointing-Pointer BMC-derived activated PSCs can produce PDGF and TGF {beta}1. -- Abstract: Bone marrow cell (BMC)-derived myofibroblast-like cells have been reported in various organs, including the pancreas. However, the contribution of these cells to pancreatic fibrosis has not been fully discussed. The present study examined the possible involvement of pancreatic stellate cells (PSCs) originating from BMCs in the development of pancreatic fibrosis in a clinically relevant rat model of acute pancreatitis induced by a choline-deficient/ethionine-supplemented (CDE) diet. BMCs from female transgenic mice ubiquitously expressing green fluorescent protein (GFP) were transplanted into lethally irradiated male rats. Once chimerism was established, acute pancreatitis was induced by a CDE diet. Chronological changes in the number of PSCs originating from the donor BMCs were examined using double immunofluorescence for GFP and markers for PSCs, such as desmin and alpha smooth muscle actin ({alpha}SMA), 1, 3 and 8 weeks after the initiation of CDE feeding. We also used immunohistochemical staining to evaluate whether the PSCs from the BMCs produce growth factors, such as platelet-derived growth factor (PDGF) and transforming growth factor (TGF) {beta}1. The percentage of BMC-derived activated PSCs increased significantly, peaking after 1 week of CDE treatment (accounting for 23.3 {+-} 0.9% of the total population of activated PSCs) and then decreasing. These cells produced both PDGF and TGF{beta}1 during the early stage of pancreatic fibrosis. Our results suggest that PSCs originating from BMCs contribute mainly to the early stage of pancreatic injury, at least in part, by producing growth factors in a rat CDE diet-induced pancreatitis model.

  3. Monosodium Glutamate Dietary Consumption Decreases Pancreatic β-Cell Mass in Adult Wistar Rats

    PubMed Central

    Boonnate, Piyanard; Waraasawapati, Sakda; Hipkaeo, Wiphawi; Pethlert, Supattra; Sharma, Amod; Selmi, Carlo; Prasongwattana, Vitoon; Cha’on, Ubon

    2015-01-01

    Background The amount of dietary monosodium glutamate (MSG) is increasing worldwide, in parallel with the epidemics of metabolic syndrome. Parenteral administration of MSG to rodents induces obesity, hyperglycemia, hyperlipidemia, insulin resistance, and type 2 diabetes. However, the impact of dietary MSG is still being debated. We investigated the morphological and functional effects of prolonged MSG consumption on rat glucose metabolism and on pancreatic islet histology. Methods Eighty adult male Wistar rats were randomly subdivided into 4 groups, and test rats in each group were supplemented with MSG for a different duration (1, 3, 6, or 9 months, n=20 for each group). All rats were fed ad libitum with a standard rat chow and water. Ten test rats in each group were provided MSG 2 mg/g body weight/day in drinking water and the 10 remaining rats in each group served as non-MSG treated controls. Oral glucose tolerance tests (OGTT) were performed and serum insulin measured at 9 months. Animals were sacrificed at 1, 3, 6, or 9 months to examine the histopathology of pancreatic islets. Results MSG-treated rats had significantly lower pancreatic β-cell mass at 1, 6 and 9 months of study. Islet hemorrhages increased with age in all groups and fibrosis was significantly more frequent in MSG-treated rats at 1 and 3 months. Serum insulin levels and glucose tolerance in MSG-treated and untreated rats were similar at all time points we investigated. Conclusion Daily MSG dietary consumption was associated with reduced pancreatic β-cell mass and enhanced hemorrhages and fibrosis, but did not affect glucose homeostasis. We speculate that high dietary MSG intake may exert a negative effect on the pancreas and such effect might become functionally significant in the presence or susceptibility to diabetes or NaCl; future experiments will take these crucial cofactors into account. PMID:26121281

  4. MST1: a promising therapeutic target to restore functional beta cell mass in diabetes.

    PubMed

    Ardestani, Amin; Maedler, Kathrin

    2016-09-01

    The loss of insulin-producing beta cells by apoptosis is a hallmark of all forms of diabetes mellitus. Strategies to prevent beta cell apoptosis and dysfunction are urgently needed to restore the insulin-producing cells and to prevent severe diabetes progression. We recently identified the serine/threonine kinase known as mammalian sterile 20-like kinase 1 (MST1) as a critical regulator of apoptotic beta cell death and dysfunction. MST1 activates several apoptotic signalling pathways, which further stimulate its own cleavage, leading to a vicious cycle of cell death. This led us to hypothesise that MST1 signalling is central to the initiation of beta cell death in diabetes. We found that MST1 is strongly activated in a diabetic beta cell and induces not only its death but also directly impairs insulin secretion through promoting proteasomal degradation of key beta cell transcription factor, pancreatic and duodenal homeobox 1 (PDX1), which is critical for insulin production.Pre-clinical studies in various animal models of diabetes have reported that MST1 deficiency remarkably restores normoglycaemia and beta cell function and prevents the development of diabetes. Importantly, MST1 deficiency can revert fully diabetic beta cells to a non-diabetic state. MST1 may serve as a target for the development of novel therapies for diabetes that trigger the cause of the disease, namely, the destruction of the beta cells. The major current focus of our investigation is to identify and test the efficacy of potent inhibitors of this death signalling pathway to protect beta cells against the effects of autoimmune attack in type 1 diabetes and to preserve beta cell mass and function in type 2 diabetes. This review summarises a presentation given at the 'Can we make a better beta cell?' symposium at the 2015 annual meeting of the EASD. It is accompanied by two other reviews on topics from this symposium (by Heiko Lickert and colleagues, DOI: 10.1007/s00125-016-3949-9 , and by Harry

  5. Precise expression of Fis1 is important for glucose responsiveness of beta cells.

    PubMed

    Schultz, Julia; Waterstradt, Rica; Kantowski, Tobias; Rickmann, Annekatrin; Reinhardt, Florian; Sharoyko, Vladimir; Mulder, Hindrik; Tiedge, Markus; Baltrusch, Simone

    2016-07-01

    Mitochondrial network functionality is vital for glucose-stimulated insulin secretion in pancreatic beta cells. Altered mitochondrial dynamics in pancreatic beta cells are thought to trigger the development of type 2 diabetes mellitus. Fission protein 1 (Fis1) might be a key player in this process. Thus, the aim of this study was to investigate mitochondrial morphology in dependence of beta cell function, after knockdown and overexpression of Fis1. We demonstrate that glucose-unresponsive cells with impaired glucose-stimulated insulin secretion (INS1-832/2) showed decreased mitochondrial dynamics compared with glucose-responsive cells (INS1-832/13). Accordingly, mitochondrial morphology visualised using MitoTracker staining differed between the two cell lines. INS1-832/2 cells formed elongated and clustered mitochondria, whereas INS1-832/13 cells showed a homogenous mitochondrial network. Fis1 overexpression using lentiviral transduction significantly improved glucose-stimulated insulin secretion and mitochondrial network homogeneity in glucose-unresponsive cells. Conversely, Fis1 downregulation by shRNA, both in primary mouse beta cells and glucose-responsive INS1-832/13 cells, caused unresponsiveness and significantly greater numbers of elongated mitochondria. Overexpression of FIS1 in primary mouse beta cells indicated an upper limit at which higher FIS1 expression reduced glucose-stimulated insulin secretion. Thus, FIS1 was overexpressed stepwise up to a high concentration in RINm5F cells using the RheoSwitch system. Moderate FIS1 expression improved glucose-stimulated insulin secretion, whereas high expression resulted in loss of glucose responsiveness and in mitochondrial artificial loop structures and clustering. Our data confirm that FIS1 is a key regulator in pancreatic beta cells, because both glucose-stimulated insulin secretion and mitochondrial dynamics were clearly adapted to precise expression levels of this fission protein. PMID:27179109

  6. Decreased basal insulin secretion from pancreatic islets of pups in a rat model of maternal obesity.

    PubMed

    Zambrano, Elena; Sosa-Larios, Tonantzin; Calzada, Lizbeth; Ibáñez, Carlos A; Mendoza-Rodríguez, Carmen A; Morales, Angélica; Morimoto, Sumiko

    2016-10-01

    Maternal obesity (MO) is a deleterious condition that enhances susceptibility of adult offspring to metabolic diseases such as type 2 diabetes. The objective is to study the effect of MO on in vitro insulin secretion and pancreatic cellular population in offspring. We hypothesize that a harmful antenatal metabolic environment due to MO diminishes the basal glucose-responsive secretory function of pancreatic beta cells in offspring. Mothers were fed a control (C) or high-fat diet from weaning through pregnancy (120 days) and lactation. At postnatal days (PNDs) 36 and 110, pups were killed, peripheral blood was collected and pancreatic islets were isolated. Basal insulin secretion was measured in vitro in islets for 60 min. It was found that blood insulin, glucose and homeostasis model assessment (HOMA) index were unaffected by maternal diet and age in females. However, male MO offspring at PND 110 showed hyperinsulinemia and insulin resistance compared with C. Body weight was not modified by MO, but fat content was higher in MO pups compared with C pups. Triglycerides and leptin concentrations were higher in MO than in C offspring in all groups except in females at PND 36. Pancreatic islet cytoarchitecture was unaffected by MO. At PND 36, islets of male and female C and MO offspring responded similarly to glucose, but at PND 110, male and female MO offspring islets showed a 50% decrease in insulin secretion. It was concluded that MO impairs basal insulin secretion of offspring with a greater impact on males than females, and this effect mainly manifests in adulthood. PMID:27496224

  7. Effects of everolimus on a rat model of cerulein-induced experimental acute pancreatitis

    PubMed Central

    Özkardeş, Alper Bilal; Bozkurt, Birkan; Dumlu, Ersin Gürkan; Tokaç, Mehmet; Yazgan, Aylin Kılıç; Ergin, Merve; Erel, Özcan; Kılıç, Mehmet

    2015-01-01

    Objective: To analyze the biochemical and histopathological effects of everolimus in an experimental rat model of cerulein-induced acute pancreatitis. The aim of the present study was to determine the effects of everolimus on blood biochemical parameters and tissue histopathology in an experimental rat model of cerulein-induced acute pancreatitis. Material and Methods: In 30 Wistar albino rats (male; 240–260 g), acute pancreatitis was induced by an intraperitoneal injection of cerulein (50 μg/kg) administered twice in 2 h. They were equally divided into the following three groups: 0.9% isotonic solution (Group 1; control), everolimus once (Group 2), and everolimus twice (Group 3) by oral gavage after cerulein injection. Thirty hours after the induction of pancreatitis, blood samples were collected by direct intracardiac puncture, rats were sacrificed, and pancreatic tissue samples were obtained. Results: Biochemical analyses of the blood samples showed statistically significant difference in red blood cell count as well as hemoglobin, hematocrit, urea, and alanine transaminase levels among the study groups (p<0.05 in all). Everolimus proved to significantly increase red blood cell count in a dose-independent manner. Hemoglobin and hematocrit levels significantly increased only after treatment with one dose of everolimus. Urea level was significantly different between the Groups 2 and 3; however, no change was observed in both groups when compared with the control. Alanine transaminase level significantly decreased only after treatment with two doses of everolimus. Histopathological analyses revealed that everolimus significantly decreased inflammation and perivascular infiltrate in a dose-dependent manner (35% in Group 2, 75% in Group 3; p=0.048). Conclusion: Treatment with two doses of everolimus improved some biochemical and histopathological parameters of experimental rat models of cerulein-induced acute pancreatitis and implied the specific inhibition of

  8. Pancreatitis

    MedlinePlus

    ... open. Balloon dilatation. Some endoscopes have a small balloon that the doctor uses to dilate, or stretch, a narrowed pancreatic or bile duct. A temporary stent may be placed for a few months to ...

  9. Translation attenuation through eIF2α phosphorylation prevents oxidative stress and maintains the differentiated state in beta cells

    PubMed Central

    Back, Sung Hoon; Scheuner, Donalyn; Han, JaeSeok; Song, Benbo; Ribick, Mark; Wang, Junying; Gildersleeve, Robert D.; Pennathur, Subramaniam; Kaufman, Randal J.

    2009-01-01

    SUMMARY Accumulation of unfolded protein within the endoplasmic reticulum (ER) lumen attenuates mRNA translation through activation of the protein kinase PERK and subsequent phosphorylation of eukaryotic initiation factor 2 on Ser51 of the alpha subunit (eIF2α). Genetic disruption of the PERK/eIF2α pathway in humans and mice produces severe pancreatic beta cell deficiency and post-natal lethality. To elucidate the role of eIF2α phosphorylation in beta cells, we have rescued the lethality of homozygous eIF2α Ser51Ala mice by expression of a loxP-flanked wild-type eIF2α transgene. Beta cell-specific transgene deletion to prevent eIF2α phosphorylation caused a severe diabetic phenotype due to heightened, unregulated proinsulin translation, defective intracellular trafficking of secretory and plasma membrane proteins, increased oxidative damage, reduced expression of stress response and beta cell-specific genes, and apoptosis. However, glucose intolerance and beta cell death in these mice were attenuated by antioxidant treatment. We conclude that phosphorylation of eIF2α coordinately attenuates mRNA translation, prevents oxidative stress, and optimizes ER protein folding to support insulin production in the beta cell. These findings that show increased proinsulin synthesis causes oxidative stress leading to beta cell failure may reflect events in the beta cell loss associated with insulin resistance in type 2 diabetes. PMID:19583950

  10. Islet Neogenesis Associated Protein (INGAP) induces the differentiation of an adult human pancreatic ductal cell line into insulin-expressing cells through stepwise activation of key transcription factors for embryonic beta cell development.

    PubMed

    Assouline-Thomas, Béatrice; Ellis, Daniel; Petropavlovskaia, Maria; Makhlin, Julia; Ding, Jieping; Rosenberg, Lawrence

    2015-01-01

    Regeneration of β-cells in diabetic patients is an important goal of diabetes research. Islet Neogenesis Associated Protein (INGAP) was discovered in the partially duct-obstructed hamster pancreas. Its bioactive fragment, pentadecapeptide 104-118 (INGAP-P), has been shown to reverse diabetes in animal models and to improve glucose homeostasis in patients with diabetes in clinical trials. Further development of INGAP as a therapy for diabetes requires identification of target cells in the pancreas and characterization of the mechanisms of action. We hypothesized that adult human pancreatic ductal cells retain morphogenetic plasticity and can be induced by INGAP to undergo endocrine differentiation. To test this hypothesis, we treated the normal human pancreatic ductal cell line (HPDE) with either INGAP-P or full-length recombinant protein (rINGAP) for short-term periods. Our data show that this single drug treatment induces both proliferation and transdifferentiation of HPDE cells, the latter being characterized by the rapid sequential activation of endocrine developmental transcription factors Pdx-1, Ngn3, NeuroD, IA-1, and MafA and subsequently the expression of insulin at both the mRNA and the protein levels. After 7 days, C-peptide was detected in the supernatant of INGAP-treated cells, reflecting their ability to secrete insulin. The magnitude of differentiation was enhanced by embedding the cells in Matrigel, which led to islet-like cluster formation. The islet-like clusters cells stained positive for nuclear Pdx-1 and Glut 2 proteins, and were expressing Insulin mRNA. These new data suggest that human adult pancreatic ductal cells retain morphogenetic plasticity and demonstrate that a short exposure to INGAP triggers their differentiation into insulin-expressing cells in vitro. In the context of the urgent search for a regenerative and/or cellular therapy for diabetes, these results make INGAP a promising therapeutic candidate. PMID:26558987

  11. Copper deficiency in rats increases pancreatic enkephalin-containing peptides and insulin.

    PubMed

    Recant, L; Voyles, N R; Timmers, K I; Zalenski, C; Fields, M; Bhathena, S J

    1986-01-01

    Free enkephalins (enk) and higher molecular weight enkephalin-containing peptides (enk-c-p) are present in the endocrine pancreas of rats, presumably in B cells. To determine whether these opioid peptides show dynamic alterations as insulin content of pancreas changes, we utilized a copper deficient rat model, in which the exocrine pancreas atrophies and the endocrine pancreas is "intact" and insulin (IRI) content increases. Dietary copper deficiency (-C) was produced in weanling male rats for 4 and 7 weeks. The deficient and copper supplemented (+C) groups were further subdivided to receive all dietary carbohydrate as either 62% fructose (F) or 62% starch (S). -CF rats showed the most severe deficiency. After 7 weeks, total units of pancreatic IRI in -CF were 7.5 +CF 2.1, -CS 7.9 and in +CS 2.8 (p less than 0.001). Pancreatic content of Met5- and Leu5-enk was measured in extracts which were purified on C-18 Seppaks with and without prior treatment with trypsin and carboxypeptidase B. -C animals showed progressive, significant increases in pancreatic content of Leu-enk-c-p, with a decrease in free Leu- and Met-enk (p less than 0.02-0.01). The pancreatic findings are compatible with a co-localization of enkephalins and insulin in the endocrine pancreas and are suggestive of co-regulation. PMID:3550724

  12. Maturation of adult beta-cells revealed using a Pdx1/insulin dual-reporter lentivirus.

    PubMed

    Szabat, Marta; Luciani, Dan S; Piret, James M; Johnson, James D

    2009-04-01

    The enigmatic process of beta-cell maturation has significant implications for diabetes pathogenesis, and potential diabetes therapies. This study examined the dynamics and heterogeneity of insulin and pancreatic duodenal homeobox (Pdx)-1 gene expression in adult beta-cells. Insulin and Pdx1 expression were monitored in human and mouse islet cells and MIN6 cells using a Pdx1-monomeric red fluorescent protein/insulin-enhanced green fluorescent protein dual-reporter lentivirus. The majority of fluorescent cells were highly positive for both Pdx1 and insulin. Cells expressing Pdx1 but little or no insulin (Pdx1(+)/Ins(low)) comprised 15-25% of the total population. Time-lapse imaging demonstrated that Pdx1(+)/Ins(low) primary beta-cells and MIN6 cells could convert to Pdx1(+)/Ins(+) cells without cell division. Genes involved in the mature beta-cell phenotype (Glut2, MafA) were expressed at higher levels in Pdx1(+)/Ins(+) cells relative to Pdx1(+)/Ins(low) cells. Conversely, genes implicated in early beta-cell development (MafB, Nkx2.2) were enriched in Pdx1(+)/Ins(low) cells. Sorted Pdx1(+)/Ins(low) MIN6 cells had a higher replication rate and secreted less insulin relative to double-positive cells. Long-term phenotype tracking of Pdx1(+)/Ins(low) cells showed two groups, one that matured into Pdx1(+)/Ins(+) cells and one that remained immature. These results demonstrate that adult beta-cells pass through distinct maturation states, which is consistent with previously observed heterogeneity in insulin and Pdx1 expression in adult beta-cells. At a given time, a proportion of adult beta-cells share similar characteristics to functionally immature embryonic beta-cell progenitors. The maturation of adult beta-cells recapitulates development in that Pdx1 expression precedes the robust expression of insulin and other mature beta-cell genes. These results have implications for harnessing the maturation process for therapeutic purposes. PMID:19095744

  13. Extract of grapefruit-seed reduces acute pancreatitis induced by ischemia/reperfusion in rats: possible implication of tissue antioxidants.

    PubMed

    Dembinski, A; Warzecha, Z; Konturek, S J; Ceranowicz, P; Dembinski, M; Pawlik, W W; Kusnierz-Cabala, B; Naskalski, J W

    2004-12-01

    Grapefruit seed extract (GSE) has been shown to exert antibacterial, antifungal and antioxidant activity possibly due to the presence of naringenin, the flavonoid with cytoprotective action on the gastric mucosa. No study so far has been undertaken to determine whether this GSE is also capable of preventing acute pancreatic damage induced by ischemia/reperfusion (I/R), which is known to result from reduction of anti-oxidative capability of pancreatic tissue, and whether its possible preventive effect involves an antioxidative action of this biocomponent. In this study carried out on rats with acute hemorrhagic pancreatitis induced by 30 min partial pancreatic ischemia followed by 6 h of reperfusion, the GSE or vehicle (vegetable glycerin) was applied intragastrically in gradually increasing amounts (50-500 microl) 30 min before I/R. Pretreatment with GSE decreased the extent of pancreatitis with maximal protective effect of GSE at the dose 250 microl. GSE reduced the pancreatitis-evoked increase in serum lipase and poly-C specific ribonuclease activity, and attenuated the marked fall in pancreatic blood flow and pancreatic DNA synthesis. GSE administered alone increased significantly pancreatic tissue content of lipid peroxidation products, malondialdehyde and 4-hydroxyalkens, and when administered before I/R, GSE reduced the pancreatitis-induced lipid peroxidation. We conclude that GSE exerts protective activity against I/R-induced pancreatitis probably due to the activation of antioxidative mechanisms in the pancreas and the improvement of pancreatic blood flow. PMID:15613745

  14. Chronic ethanol consumption induces gene expression of pancreatic monitor peptide, but not SPINK1/PSTI-56, in rats.

    PubMed

    Li, H S; Deng, X Y; Thompson, B S; Zhang, J Y; Wood, P G; Eagon, P K; Whitcomb, D C

    2001-08-01

    The primary factors that predispose humans to the development of alcoholic pancreatitis are unknown. One of the earliest observations in humans in whom this disease develops is pancreatic hypersecretion caused by unknown mechanisms. Messenger RNA (mRNA) differential display was performed in a rat model to investigate the molecular mechanisms associated with ethanol-induced pancreatic hypersecretion. Male Wistar rats were pair-fed Lieber-DeCarli diets with or without ethanol for 7 days or 4 weeks. Total RNA was extracted from the pancreas and its neurohormonal control sites. Differentially expressed complementary DNA (cDNA) tags were isolated, cloned, and sequenced. One 248-bp cDNA was consistently and strongly induced in the pancreata of rats fed ethanol for 4 weeks. The sequence was highly homologous to both rat pancreatic monitor peptide (MP) and pancreatic secretory trypsin inhibitor (PSTI-56), also known as serine protease inhibitor, Kazal type 1 (SPINK1). Confirmatory reverse-transcription-polymerase chain reaction showed that PSTI-56 expression remained unchanged, whereas MP mRNA levels were elevated more than four times in the pancreata of ethanol-fed rats. These results indicate that long-term ethanol ingestion increases MP mRNA levels in the rat pancreas. Because MP stimulates cholecystokinin release and cholecystokinin is an important stimulant of pancreatic secretion, the enhanced MP gene expression may contribute to pancreatic hypersecretion. PMID:11484913

  15. Ischemia-reperfusion rat model of acute pancreatitis: protein carbonyl as a putative early biomarker of pancreatic injury.

    PubMed

    Schanaider, Alberto; de Carvalho, Thales Penna; de Oliveira Coelho, Simone; Renteria, Juan Miguel; Eleuthério, Elis Cristina Araújo; Castelo-Branco, Morgana Teixeira Lima; Madi, Kalil; Baetas-da-Cruz, Wagner; de Souza, Heitor Siffert Pereira

    2015-08-01

    Acute pancreatitis (AP) is an inflammatory disorder that can affect adjacent and/or remote organs. Some evidence indicates that the production of reactive oxygen species is able to induce AP. Protein carbonyl (PC) derivatives, which can also be generated through oxidative cleavage mechanisms, have been implicated in several diseases, but there is little or no information on this biomarker in AP. We investigated the association between some inflammatory mediators and PC, with the severity of ischemia-reperfusion AP. Wistar rats (n = 56) were randomly assigned in the following groups : control; sham, 15- or 180-min clamping of splenic artery, with 24 or 72 h of follow-up. The relationships between serum level of PC and thiobarbituric acid reactive species (TBARS) to myeloperoxidase (MPO) activity in tissue homogenates and to cytokines in culture supernatants of pancreatic samples were analyzed. MPO activity was related to the histology scores and increased in all clamping groups. Tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin-6 were higher in the 180-min groups. Significant correlations were found between MPO activity and the concentrations of TNF-α and IL-1β. PC levels increased in the 15-min to 24-h group. TBARS levels were not altered substantially. MPO activity and TNF-α and IL-1β concentrations in pancreatic tissue are correlated with AP severity. Serum levels of PC appear to begin to rise early in the course of the ischemia-reperfusion AP and are no longer detected at later stages in the absence of severe pancreatitis. These data suggest that PC can be an efficient tool for the diagnosis of early stages of AP. PMID:24934325

  16. Triphenyltin impairs a protein kinase A (PKA)-dependent increase of cytosolic Na{sup +} and Ca{sup 2+} and PKA-independent increase of cytosolic Ca{sup 2+} associated with insulin secretion in hamster pancreatic {beta}-cells

    SciTech Connect

    Miura, Yoshikazu . E-mail: y-miura@dokkyomed.ac.jp; Matsui, Hisao

    2006-11-01

    Oral administration of triphenyltin chloride (TPT) (60 mg/kg body weight) inhibits the insulin secretion by decreasing the cytoplasmic Ca{sup 2+} concentration ([Ca{sup 2+}] {sub i}) induced by glucose-dependent insulinotropic polypeptide (GIP) in pancreatic {beta}-cells of the hamster. To test the possibility that the abnormal level of [Ca{sup 2+}] {sub i} induced by TPT administration could be due to a defect in the cAMP-dependent cytoplasmic Na{sup +} concentration ([Na{sup +}] {sub i}) in the {beta}-cells, we investigated the effects of TPT administration on the changes of [Na{sup +}] {sub i} induced by GIP, glucagon-like peptide-1 (GLP-1), or forskolin, an activator of adenylyl cyclase, and on the changes of [Na{sup +}] {sub i} or [Ca{sup 2+}] {sub i} induced by 6-Bnz-cAMP, an activator of protein kinase A (PKA), and 8-pCPT-2'-O-Me-cAMP, an activator of Epac. The [Na{sup +}] {sub i} and [Ca{sup 2+}] {sub i} were measured in islet cells loaded with sodium-binding benzofuran isophthalate (SBFI) and fura-2, respectively. In the presence of 135 mM Na{sup +}, TPT administration significantly reduced the rise in [Na{sup +}] {sub i} by 10 nM GLP-1, 10 {mu}M forskolin, and 50 {mu}M 6-Bnz-cAMP, but had not effect in a Na{sup +}-free medium. In the presence of 135 mM Na{sup +}, TPT administration also reduced the rise in [Ca{sup 2+}] {sub i} by 8-pCPT-2'-O-Me-cAMP plus10 {mu}M H-89, a inhibitor of PKA, and 6-Bnz-cAMP. Moreover, TPT administration significantly reduced the insulin secretion by 2 mM db-cAMP, GLP-1, GIP, and 8-pCPT-2'-O-Me-cAMP with and without H-89, and that by 6-Bnz-cAMP and forskolin. Our study suggested that TPT has inhibitory effects on the cellular Ca{sup 2+} response due to a reduced Na{sup +} permeability through PKA-dependent mechanisms in hamster islet cells. Also TPT has the reduction of [Ca{sup 2+}] {sub i} related to Na{sup +}-dependent insulin secretion after an activation of Epac.

  17. Emodin enhances alveolar epithelial barrier function in rats with experimental acute pancreatitis

    PubMed Central

    Xia, Xian-Ming; Wang, Fang-Yu; Wang, Zhen-Kai; Wan, Hai-Jun; Xu, Wen-An; Lu, Heng

    2010-01-01

    AIM: To investigate the effect of emodin on expression of claudin-4, claudin-5 and occludin, as well as the alveolar epithelial barrier in rats with pancreatitis induced by sodium taurocholate. METHODS: Experimental pancreatitis was induced by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. Emodin was injected via the external jugular vein 3 h after induction of acute pancreatitis. Rats from sham operation group and acute pancreatitis group were injected with normal saline (an equivalent volume as emodin) at the same time point. Samples of lung and serum were obtained 6 h after drug administration. Pulmonary morphology was examined with HE staining. Pulmonary edema was estimated by measuring water content in lung tissue samples. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) level were measured by enzyme-linked immunospecific assay. Serum amylase and pulmonary myeloperoxidase (MPO) activity were detected by spectrophotometry. Alveolar epithelial barrier was assessed by pulmonary dye extravasation. Expression of claudin-4, claudin-5 and occludin in lung tissue samples was examined by immunohistology, quantitative real-time reverse transcription polymerase chain reaction and Western blotting analysis, respectively. RESULTS: Pancreatitis-associated lung injury was characterized by pulmonary edema, leukocyte infiltration, alveolar collapse, and elevated serum amylase level. The pulmonary damage, pulmonary pathological scores, serum amylase and MPO activity, TNF-α and IL-6 levels, and wet/dry ratio were decreased in rats after treatment with emodin. Immunostaining of claudin-4, claudin-5 and occludin was detected in lung tissue samples from rats in sham operation group, which was distributed in alveolar epithelium, vascular endothelium, and bronchial epithelium, respectively. The mRNA and protein expression levels of claudin-4, claudin-5 and occludin in lung tissue samples were markedly decreased, the expression level of

  18. A synopsis of factors regulating beta cell development and beta cell mass.

    PubMed

    Prasadan, Krishna; Shiota, Chiyo; Xiangwei, Xiao; Ricks, David; Fusco, Joseph; Gittes, George

    2016-10-01

    The insulin-secreting beta cells in the endocrine pancreas regulate blood glucose levels, and loss of functional beta cells leads to insulin deficiency, hyperglycemia (high blood glucose) and diabetes mellitus. Current treatment strategies for type-1 (autoimmune) diabetes are islet transplantation, which has significant risks and limitations, or normalization of blood glucose with insulin injections, which is clearly not ideal. The type-1 patients can lack insulin counter-regulatory mechanism; therefore, hypoglycemia is a potential risk. Hence, a cell-based therapy offers a better alternative for the treatment of diabetes. Past research was focused on attempting to generate replacement beta cells from stem cells; however, recently there has been an increasing interest in identifying mechanisms that will lead to the conversion of pre-existing differentiated endocrine cells into beta cells. The goal of this review is to provide an overview of several of the key factors that regulate new beta cell formation (neogenesis) and beta cell proliferation. PMID:27105622

  19. Somatostatin receptor expression and biological functions in endocrine pancreatic cells: review based on a doctoral thesis.

    PubMed

    Ludvigsen, Eva

    2007-01-01

    Type 1 diabetes is resulting from the selective destruction of insulin-producing betacells within the pancreatic islets. Somatostatin acts as an inhibitor of hormone secretion through specific receptors (sst1-5). All ssts were expressed in normal rat and mouse pancreatic islets, although the expression intensity and the co-expression pattern varied between ssts as well as between species. This may reflect a difference in response to somatostatin in islet cells of the two species. The Non-Obese Diabetic (NOD) mouse model is an experimental model of type 1 diabetes, with insulitis accompanied by spontaneous hyperglycaemia. Pancreatic specimens from NOD mice at different age and stage of disease were stained for ssts. The islet cells of diabetic NOD mice showed increased islet expression of sst2-5 compared to normoglycemic NOD mice. The increase in sst2-5 expression in the islets cells may suggest either a contributing factor in the process leading to diabetes, or a defense response against ongoing beta-cell destruction. Somatostatin analogues were tested on a human endocrine pancreatic tumour cell line and cultured pancreatic islets. Somatostatin analogues had an effect on cAMP accumulation, chromogranin A secretion and MAP kinase activity in the cell line. Treatment of rat pancreatic islets with somatostatin analogues with selective receptor affinity was not sufficient to induce an inhibition of insulin and glucagon secretion. However, a combination of selective analogues or non-selective analogues via costimulation of receptors can cause inhibition of hormone production. For insulin and glucagon, combinations of sst2 + sst5 and sst1 + sst2, respectively, showed a biological effect. In summary, knowledge of islet cell ssts expression and the effect of somatostatin analogues with high affinity to ssts may be valuable in the future attempts to influence beta-cell function in type 1 diabetes mellitus, since down-regulation of beta-cell function may promote survival of

  20. Free radicals and the pathogenesis of type 1 diabetes: beta-cell cytokine-mediated free radical generation via cyclooxygenase-2.

    PubMed

    Tabatabaie, Tahereh; Vasquez-Weldon, Angelica; Moore, Danny R; Kotake, Yashige

    2003-08-01

    Free radical formation evoked by proinflammatory cytokines has been suggested to be involved in the destruction of beta-cells in the course of type 1 diabetes development. However, there is no direct evidence to support this hypothesis. In this study, we used electron paramagnetic resonance spectroscopy in conjunction with spin-trapping methodology to directly determine whether cytokines give rise to free radical formation in the islets. Our results demonstrate that direct, in vivo administration of tumor necrosis factor-alpha (1,000 units), interleukin-1beta (1,000 units), and interferon-gamma (2,000 units) into the rat pancreas through a bile duct cannula leads to the formation of lipid-derived free radicals in this tissue. These free radicals most likely are generated by the beta-cells because previous depletion of these cells by streptozotocin abolished the cytokine-induced free radical formation. Furthermore, macrophage depletion was found to decrease the production of free radicals. Inhibition of the enzyme inducible cyclooxygenase (COX-2) and the transcription factor nuclear factor-kappaB (NF-kappaB) significantly diminished the free radicals' signal intensity, implicating these factors in the formation of free radicals. We have also demonstrated that cytokine treatment leads to the activation of NF-kappaB in the pancreatic islets of the rats. PMID:12882915

  1. Pancreatic islet blood flow in conscious rats during hyperglycemia and hypoglycemia.

    PubMed

    Iwase, M; Tashiro, K; Uchizono, Y; Goto, D; Yoshinari, M

    2001-06-01

    Anesthesia affects general hemodynamics and regulation of organ perfusion. We used colored microspheres to measure pancreatic islet blood flow in conscious rats at two time points, during either hyperglycemia or hypoglycemia. This method, using black and green microspheres, was validated by comparison with previous microsphere experiments and by lack of effect of a nonmetabolizable glucose analog, 3-O-methylglucose, on islet perfusion. Basal and glucose-stimulated islet blood flow levels were similar in pentobarbital sodium-anesthetized and conscious rats. However, the basal distribution of pancreatic blood flow was altered by anesthesia (fractional islet blood flow 5.8 +/- 0.4% in conscious rats, 7.9 +/- 0.8% in pentobarbital-anesthetized rats, P < 0.05). Insulin-induced hypoglycemia significantly increased whole pancreatic blood flow in conscious rats, whereas islet blood flow remained unchanged and fractional islet blood flow was decreased (5.8 +/- 0.5% in the basal state, 4.2 +/- 0.4% during hypoglycemia, P < 0.001). Methylatropine pretreatment significantly increased islet blood flow during hypoglycemia by 181%. This result suggests that prevention of hypoglycemia-induced increase in islet perfusion may be mediated, at least in part, by a cholinergic, vagal muscarinic mechanism. PMID:11353660

  2. The Protective Effects of Shen-Fu Injection on Experimental Acute Pancreatitis in a Rat Model

    PubMed Central

    Huang, Lei; Cao, Jun

    2014-01-01

    Objectives. In the present study, we investigated the protective effects of Shen-Fu injection (SFI) on a caerulein-induced rat pancreatitis (AP) model. Methods. SFI was given to rats in the SFI treated group through intraperitoneal injection. Blood and pancreas samples were collected for serological and histopathological studies. Results. Our results showed that AP caused significant decrease in tissue glutathione (GSH) and serum IL-4 and IL-10, while pancreatic malondialdehyde (MDA) and myeloperoxidase (MPO) were increased. Furthermore, TNF-α, IL-1β, amylase, and lipase levels were also significantly increased. On the other hand, SFI treatment reserved all these biochemical indices as well as histopathologic alterations that were induced by caerulein. Conclusion. Our findings suggest that the SFI protects against caerulein-induced AP in rats via modulation of cytokines, oxidative stress, and Nuclear Factor-kappa B (NF-κB) activity. PMID:24738018

  3. Assessment of benzene induced oxidative impairment in rat isolated pancreatic islets and effect on insulin secretion.

    PubMed

    Bahadar, Haji; Maqbool, Faheem; Mostafalou, Sara; Baeeri, Maryam; Rahimifard, Mahban; Navaei-Nigjeh, Mona; Abdollahi, Mohammad

    2015-05-01

    Benzene (C6H6) is an organic compound used in petrochemicals and numerous other industries. It is abundantly released to our environment as a chemical pollutant causing widespread human exposure. This study mainly focused on benzene induced toxicity on rat pancreatic islets with respect to oxidative damage, insulin secretion and glucokinase (GK) activity. Benzene was dissolved in corn oil and administered orally at doses 200, 400 and 800mg/kg/day, for 4 weeks. In rats, benzene significantly raised the concentration of plasma insulin. Also the effect of benzene on the release of glucose-induced insulin was pronounced in isolated islets. Benzene caused oxidative DNA damage and lipid peroxidation, and also reduced the cell viability and total thiols groups, in the islets of exposed rats. In conclusion, the current study revealed that pancreatic glucose metabolism is susceptible to benzene toxicity and the resultant oxidative stress could lead to functional abnormalities in the pancreas. PMID:25935538

  4. Pancreatitis

    MedlinePlus

    ... to the abdomen. In 1 out of 4 childhood cases, a cause is never found. What are the symptoms of pancreatitis? Inflammation of the pancreas is often associated with pain in the upper abdomen and/or the back which may develop slowly, ...

  5. Toward beta cell replacement for diabetes

    PubMed Central

    Johannesson, Bjarki; Sui, Lina; Freytes, Donald O; Creusot, Remi J; Egli, Dieter

    2015-01-01

    The discovery of insulin more than 90 years ago introduced a life-saving treatment for patients with type 1 diabetes, and since then, significant progress has been made in clinical care for all forms of diabetes. However, no method of insulin delivery matches the ability of the human pancreas to reliably and automatically maintain glucose levels within a tight range. Transplantation of human islets or of an intact pancreas can in principle cure diabetes, but this approach is generally reserved for cases with simultaneous transplantation of a kidney, where immunosuppression is already a requirement. Recent advances in cell reprogramming and beta cell differentiation now allow the generation of personalized stem cells, providing an unlimited source of beta cells for research and for developing autologous cell therapies. In this review, we will discuss the utility of stem cell-derived beta cells to investigate the mechanisms of beta cell failure in diabetes, and the challenges to develop beta cell replacement therapies. These challenges include appropriate quality controls of the cells being used, the ability to generate beta cell grafts of stable cellular composition, and in the case of type 1 diabetes, protecting implanted cells from autoimmune destruction without compromising other aspects of the immune system or the functionality of the graft. Such novel treatments will need to match or exceed the relative safety and efficacy of available care for diabetes. PMID:25733347

  6. Toward beta cell replacement for diabetes.

    PubMed

    Johannesson, Bjarki; Sui, Lina; Freytes, Donald O; Creusot, Remi J; Egli, Dieter

    2015-04-01

    The discovery of insulin more than 90 years ago introduced a life-saving treatment for patients with type 1 diabetes, and since then, significant progress has been made in clinical care for all forms of diabetes. However, no method of insulin delivery matches the ability of the human pancreas to reliably and automatically maintain glucose levels within a tight range. Transplantation of human islets or of an intact pancreas can in principle cure diabetes, but this approach is generally reserved for cases with simultaneous transplantation of a kidney, where immunosuppression is already a requirement. Recent advances in cell reprogramming and beta cell differentiation now allow the generation of personalized stem cells, providing an unlimited source of beta cells for research and for developing autologous cell therapies. In this review, we will discuss the utility of stem cell-derived beta cells to investigate the mechanisms of beta cell failure in diabetes, and the challenges to develop beta cell replacement therapies. These challenges include appropriate quality controls of the cells being used, the ability to generate beta cell grafts of stable cellular composition, and in the case of type 1 diabetes, protecting implanted cells from autoimmune destruction without compromising other aspects of the immune system or the functionality of the graft. Such novel treatments will need to match or exceed the relative safety and efficacy of available care for diabetes. PMID:25733347

  7. Beneficial effects of the ethanol extract from the dry matter of a culture broth of Inonotus obliquus in submerged culture on the antioxidant defence system and regeneration of pancreatic beta-cells in experimental diabetes in mice.

    PubMed

    Xu, Hong-Yu; Sun, Jun-En; Lu, Zhen-Ming; Zhang, Xiao-Mei; Dou, Wen-Fang; Xu, Zheng-Hong

    2010-04-01

    The antihyperglycaemic and antilipidperoxidative effects of the ethanol extract from the dry matter of a culture broth (DMCB) of Inonotus obliquus were investigated in alloxan-induced diabetic mice and the possible mechanism of action was also discussed. In alloxan-induced diabetic mice, treatment with the ethanol extract from DMCB of I. obliquus (30 and 60 mg kg(-1) body weight (b.w.) for 21 days) showed a significant decrease in blood glucose level: the percentage reductions on the 7th day were 11.54 and 11.15%, respectively. However, feeding of this drug for three weeks produced reduction of 22.51 and 24.32%. Furthermore, the ethanol extract from the DMCB of I. obliquus treatment significantly decreased serum contents of free fatty acids, total cholesterol, triglycerides and low-density lipoprotein-cholesterol, whereas it effectively increased high-density lipoprotein-cholesterol, insulin levels and hepatic glycogen contents in livers of diabetic mice. Besides this, the ethanol extracts from the DMCB treatment significantly increased catalase, superoxide dismutase and glutathione peroxidase activities, except for decreasing the maleic dialdehyde level in diabetic mice. Histological morphology examination showed that the ethanol extract from the DMCB of I. obliquus restored the damage of pancreatic tissues in mice with diabetes mellitus. The results showed that the ethanol extract from the DMCB of I. obliquus possesses significant antihyperglycaemic, antilipidperoxidative and antioxidant effects in alloxan-induced diabetic mice. PMID:20397104

  8. Sustained Beta-Cell Dysfunction but Normalized Islet Mass in Aged Thrombospondin-1 Deficient Mice

    PubMed Central

    Emanuelsson, Hanna; Christoffersson, Gustav; Carlsson, Per-Ola

    2012-01-01

    Pancreatic islet endothelial cells have in recent years been shown to support beta-cell mass and function by paracrine interactions. Recently, we identified an islets endothelial-specific glycoprotein, thrombospondin-1 (TSP-1), that showed to be of importance for islet angiogenesis and beta-cell function in young mice. The present study aimed to investigate long-term consequences for islet morphology and beta-cell function of TSP-1 deficiency. Islet and beta-cell mass were observed increased at 10–12 weeks of age in TSP-1 deficient mice, but were normalized before 16 weeks of age when compared to wild-type controls. Islet vascularity was normal in 10–12 and 16-week-old TSP-1 deficient animals, whereas islets of one-year-old animals lacking TSP-1 were hypervascular. Beta-cell dysfunction in TSP-1 deficient animals was present at similar magnitudes between 10–12 and 52 weeks of age, as evaluated by glucose tolerance tests. The insulin secretion capacity in vivo of islets in one-year-old TSP-1 deficient animals was only ∼15% of that in wild-type animals. Using a transplantation model, we reconstituted TSP-1 in adult TSP-deficient islets. In contrast to neonatal TSP-1 deficient islets that we previously reported to regain function after TSP-1 reconstitution, adult islets failed to recover. We conclude that TSP-1 deficiency in islets causes changing vascular and endocrine morphological alterations postnatally, but is coupled to a chronic beta-cell dysfunction. The beta-cell dysfunction induced by TSP-1 deficiency is irreversible if not substituted early in life. PMID:23094049

  9. Cellular Origins of Beta Cell Regeneration: a Legacy view of Historical Controversies

    PubMed Central

    Granger, Anne; Kushner, Jake A.

    2013-01-01

    Beta cell regeneration represents a major goal of therapy for diabetes. Unraveling the origin of beta cells during pancreatic regeneration could help restore a functional beta cell mass in diabetes patients. This scientific question has represented a longstanding interest still intensively investigated today. This review focuses on pioneering observations and subsequent theories made hundred years ago and describes how technical innovation helped resolve some, but not all, of the controversies generated by these early investigators. At the end of the nineteenth century, complete pancreatectomy demonstrated the crucial physiological role of the pancreas and its link to diabetes. Pancreatic injury models, including pancreatectomy and ductal ligation, allowed investigators to describe islet function and to assess the regenerative capacity of the pancreas. Three main theories were proposed to explain the origins of newly formed islets: 1) transdifferentiation of acinar cells into islets, 2) islet neogenesis, a process reminiscent of islet formation during embryonic development, and 3) replication of preexisting islet cells. Despite considerable technical innovation in the last fifty years, the origin of new adult beta cells remains highly controversial and the same three theories are still debated today. PMID:19765178

  10. Insulin receptor alternative splicing is regulated by insulin signaling and modulates beta cell survival

    PubMed Central

    Malakar, Pushkar; Chartarifsky, Lital; Hija, Ayat; Leibowitz, Gil; Glaser, Benjamin; Dor, Yuval; Karni, Rotem

    2016-01-01

    Type 2 Diabetes (T2DM) affects more than 300 million people worldwide. One of the hallmarks of T2DM is peripheral insulin resistance, in part due to unproductive insulin signaling through the insulin receptor. The insulin receptor (INSR) exists as two isoforms, INSR-A and INSR-B, which results from skipping or inclusion of exon 11 respectively. What determines the relative abundance of the different insulin receptor splice variants is unknown. Moreover, it is not yet clear what the physiological roles of each of the isoforms are in normal and diseased beta cells. In this study, we show that insulin induces INSR exon 11 inclusion in pancreatic beta cells in both human and mouse. This occurs through activation of the Ras-MAPK/ERK signaling pathway and up-regulation of the splicing factor SRSF1. Induction of exon 11 skipping by a splice-site competitive antisense oligonucleotide inhibited the MAPK-ERK signaling pathway downstream of the insulin receptor, sensitizing the pancreatic β-cell line MIN6 to stress-induced apoptosis and lipotoxicity. These results assign to insulin a regulatory role in INSR alternative splicing through the Ras-MAPK/ERK signaling pathway. We suggest that in beta cells, INSR-B has a protective role, while INSR-A expression sensitizes beta cells to programmed cell death. PMID:27526875

  11. In vivo imaging of beta cells with radiotracers: state of the art, prospects and recommendations for development and use.

    PubMed

    Eriksson, Olof; Laughlin, Maren; Brom, Maarten; Nuutila, Pirjo; Roden, Michael; Hwa, Albert; Bonadonna, Riccardo; Gotthardt, Martin

    2016-07-01

    Radiotracer imaging is characterised by high in vivo sensitivity, with a detection limit in the lower picomolar range. Therefore, radiotracers represent a valuable tool for imaging pancreatic beta cells. High demands are made of radiotracers for in vivo imaging of beta cells. Beta cells represent only a small fraction of the volume of the pancreas (usually 1-3%) and are scattered in the tiny islets of Langerhans throughout the organ. In order to be able to measure a beta cell-specific signal, one has to rely on highly specific tracer molecules because current in vivo imaging technologies do not allow the resolution of single islets in humans non-invasively. Currently, a considerable amount of preclinical data are available for several radiotracers and three are under clinical evaluation. We summarise the current status of the evaluation of these tracer molecules and put forward recommendations for their further evaluation. PMID:27094935

  12. 1,25-Dihydroxyvitamin D/sub 3/ target cells in immature pancreatic islets

    SciTech Connect

    Clark, S.A.; Stumpf, W.E.; Sar, M.; DeLuca, H.F.

    1987-07-01

    Target cells of 1,25-dihydroxyvitamin D/sub 3/ were identified by autoradiography in islets from rats of different ages. Nuclei of pancreatic islet cells selectively concentrated 1,25-(/sup 3/H)dihydroxyvitamin D/sub 3/ but not 25-(/sup 3/H)hydroxyvitamin D/sub 3/ or 24,25-(/sup 3/H)dihydroxyvitamin D/sub 3/. Developmental studies of pancreatic islets indicated that target cells, as revealed by significant nuclear concentration of 1,25-(/sup 3/H)dihydroxyvitamin D/sub 3/, are present in islet cells of fetal rats. The percentage of islet cells that concentrated 1,25-(/sup 3/H)dihydroxyvitamin D/sub 3/ increased from 10 to 15% in the fetus to 60% at 1 day of age. Immunocytochemical staining indicated that insulin-containing cells but not glucagon or somatostatin cells concentrated 1,25-(/sup 3/H)dihydroxyvitamin D/sub 3/. Peak uptake of 1,25(/sup 3/H) dihydroxyvitamin D/sub 3/ was calculated to be 400 pmol/mg DNA, with no significant difference in nuclear accumulation between islets cells from neonatal and adult rats or between islets in vivo and isolated islets in vitro. The results of these studies indicate that (1) 1,25-(/sup 3/H)dihydroxyvitamin D/sub 3/ target cells are present in islets before pancreatic ..beta..-cells are morphologically or functionally mature; (2) islet ..beta..-cells concentrate 1,25-dihydroxyvitamin D/sub 3/, but not 25-hydroxyvitamin D/sub 3/ or 24,25-dihydroxyvitamin D/sub 3/. The authors conclude that only the 1,25-dihydroxyvitamin D/sub 3/ metabolite of vitamin D is accumulated by nuclei of developing and mature ..beta..-cells and suggest that 1,25-dihydroxyvitamin D/sub 3/ plays a role in the maturation of islet ..beta..-cells.

  13. Aqueous extract of black tea (Camellia sinensis) prevents ethanol+cholecystokinin-induced pancreatitis in a rat model.

    PubMed

    Das, Dolan; Mukherjee, Sandip; Das, Asankur S; Mukherjee, Maitrayee; Mitra, Chandan

    2006-04-01

    Black Tea Extract (BTE), a phytocompound has been attributed with a plethora of health-promoting actions. We have previously demonstrated that BTE inhibits chronic hepatitis in a rat model induced with high-fat and ethanol (EtOH). This study reports that BTE prevents altered pancreatic acinar cell functions, oxidative stress, inflammatory changes and DNA damage in the EtOH+cholecystokinin (CCK)-induced model of pancreatitis. The EtOH+CCK model rats were administered with BTE, and were examined the activity of pancreatic digestive enzymes (amylase and lipase), proinflammatory cytokines (IL-6 and TNF-alpha), oxidative and antioxidative enzymes (nitric oxide, NO; malondialdehyde, MDA; superoxide dismutase, SOD; catalase, CAT), antioxidant level (glutathione, GSH), histopathological changes and the integrity of genomic DNA. Results show that because of chronic EtOH treatment, serum level of amylase and lipase (two biomarkers for pancreatitis) and pancreatic levels of MDA and NO (two biomarkers of oxidative stress) increased significantly, which could be effectively blunted by BTE. BTE could normalize EtOH+CCK-induced suppressed activities of SOD and CAT, and GSH content of pancreatic tissue. Also, histopathological and inflammatory changes during EtOH+CCK-induced pancreatitis could be blunted by BTE. Furthermore, BTE could effectively reduce EtOH+CCK-induced increase in DNA fragmentation and damage. These findings suggest that BTE prevents pancreatitis caused by chronic EtOH+CCK toxicity presumably by enhancing antioxidant, anti-inflammatory and antiapoptotic activity in rats. PMID:16289561

  14. Expression of dynamin immunoreactivity in experimental pancreatic tumors induced in rat by mancozeb-nitrosomethylurea.

    PubMed

    Valentich, M A; Cook, T; Urrutia, R

    1996-04-19

    Dynamins are GTPases which support receptor-mediated endocytosis and bind to several tyrosine kinase receptor-associated proteins known to mediate cell proliferation and differentiation. We have recently established that dynamin expression correlates with normal neuronal (Torre et al., J. Biol. Chem., 269 (1994) 32411-32417) and acinar pancreatic cell differentiation (Cook et al., Mol. Biol. Cell, 6 (1995) 405a). To begin to understand the role of dynamin in neoplastic pancreatic cell differentiation, we have followed the expression of this protein by immunohistochemistry during the development of pancreatic tumors in a mancozeb-nitrosomethylurea (NMU)-based carcinogenesis model recently developed in our laboratory (Monis and Valentich, Carcinogenesis, 14 (1993) 929-933). After a single intraperitoneal injection (50 mg/g body wt) of this carcinogen, rats fed with mancozeb develop pancreatic focal acinar hyperplasia (FACH), dysplastic foci (DYF) displaying acinar-like and ductular-like structures, and ductular-like carcinoma in situ (CIS). After histochemical staining using a monoclonal anti-dynamin antibody, high levels of this protein are consistently observed in well-differentiated acinar tumors (FACH). In contrast, dynamin immunoreactivity is almost undetectable in more advanced lesions showing a ductular-like phenotype (ductular-like DYF and CIS). This change in the expression pattern of dynamin during the progression of acinar into ductular-like DYF and CIS lesions correlates with recent findings from our laboratory showing a differential expression pattern for dynamin in pancreatic cells during embryonic development, with ductular-like precursor cells expressing low levels of this protein. Based upon these results, we conclude that more advanced ductular-like neoplastic cells induced by the carcinogen NMU in rat pancreas behave phenotypically like pancreatic precursor cells in their pattern of expression for dynamin. PMID:8603375

  15. Lithospermic acid B protects beta-cells from cytokine-induced apoptosis by alleviating apoptotic pathways and activating anti-apoptotic pathways of Nrf2-HO-1 and Sirt1

    SciTech Connect

    Lee, Byung-Wan; Chun, Sung Wan; Kim, Soo Hyun; Lee, Yongho; Kang, Eun Seok; Cha, Bong-Soo; Lee, Hyun Chul

    2011-04-01

    Lithospermic acid B (LAB) has been reported to protect OLETF rats, an established type 2 diabetic animal model, from the development of diabetes-related vascular complications. We investigated whether magnesium lithospermate B (LAB) has a protective role under cytokine-induced apoptosis in INS-1 cells in vitro and whether it slows the development of diabetes in OLETF rats in vivo. Pretreatment with 50 {mu}M LAB significantly reduced the 1000 U/mL INF-{gamma} and 100 U/mL IL-1{beta}-induced INS-1 cell death. LAB significantly alleviated cytokine-induced phosphorylations of p38 and JNK in accordance with a decrease in cleaved caspase-3 activity in beta-cells. LAB also protected against the cytokine-induced caspase-3 apoptotic pathway via significant activation of Nrf2-HO (heme-oxigenase)-1 and Sirt1 expression. OLETF rats treated with 40 mg/kg/day LAB showed a significant improvement in glucose tolerance compared to untreated OLETF control rats in vivo. Our results suggest that the cytoprotective effects of LAB on pancreatic {beta}-cells are related with both alleviating apoptotic pathways and activating anti-apoptotic pathways of Nrf2-HO-1 and Sirt1.

  16. Endogenous and monoclonal antibodies to the rat pancreatic acinar cell Golgi complex

    PubMed Central

    1984-01-01

    Normal, unimmunized mouse serum from several strains (BALB/c, C57/b, DBA/2, NZB, SJL, CD/1) contains an endogenous IgG antibody that localizes to the Golgi complex of rat pancreatic acinar cells. Treatment of pancreatic acini with 5 microM monensin resulted in the swelling and vacuolization of the Golgi cisternae, and in a corresponding annular staining by the mouse serum as observed by immunofluorescence, suggesting that the antigen recognized is on the Golgi complex cisternal membrane. The antiserum did not react with pancreatic secretory proteins, and its binding to smooth microsomal membranes was retained following sodium carbonate washing, supporting a Golgi membrane localization. Advantage was taken of the existence of the endogenous murine antibody for the isolation of monoclonal antibodies directed to the Golgi complex of the rat pancreas. Two antibodies, antiGolgi 1 and antiGolgi 2, are described. Both antibodies are IgMs that recognize integral membrane proteins of the trans-Golgi cisternae, with lighter and patchy staining of the pancreatic lumen membrane, as observed both by light and electron microscopy. AntiGolgi 1 recognizes predominately a protein of molecular weight 103,000- 108,000, whereas antiGolgi 2 shows a strong reaction to a 180-kd band as well as the 103-108-kd protein. PMID:6373788

  17. Pancreatic enzyme and plasma cholesterol response to chronic ingestion of a nonabsorbable lipid in rats.

    PubMed

    Hager, M H; Schneeman, B O

    1986-12-01

    Pancreatic enzyme activity and plasma and high density lipoprotein (HDL) cholesterol levels were measured in rats chronically fed a nonabsorbable lipid, sucrose polyester (SPE), to determine if the rat pancreas responds to SPE as a dietary lipid or a nonnutritive ingredient. Adult male rats were fed for 28 d a diet containing either 5% or 20% corn oil, 5% SPE, 16% and 4% hydrogenated palm oil (HPO), or 16% corn oil and 4% HPO. HPO is used to prevent anal leakage of unabsorbed oil when SPE is fed at high dietary levels. Since HPO and SPE are not absorbed, rats fed SPE derive their energy from protein and carbohydrate in the diet. The tissue levels of pancreatic enzymes in rats consuming high levels of SPE in the diet resemble those of rats eating a low fat diet in which energy is derived from carbohydrate and protein. Plasma and HDL cholesterol levels were lowest in the group consuming high levels of SPE, an observation that is consistent with previous reports. These data indicate that the pancreas responds to SPE as a nonnutritive ingredient rather than a digestible dietary lipid. PMID:3806235

  18. Drug CRL 40 028-induced inhibition of pancreatic secretion in rats.

    PubMed

    Rozé, C; Chariot, J; Vaille, C

    1983-09-01

    The drug CRL 40 028 increases spontaneous motility through an action on central adrenergic receptors. The effects of this drug have been tested in rats on the external pancreatic secretion induced by secretin, CCK, acetylcholine, vagal electrical stimulation or 2 deoxy-D-glucose. CRL 40 028 had no effect on basal secretion nor on secretion stimulated by agents acting directly on pancreatic secretory cells (secretin, CCK, acetylcholine), but decreased significantly secretion induced by central or peripheral stimulation of the vagus nerves. CRL 40 028-induced inhibition of 2 DG effect was reduced by yohimbine, suggesting a participation of alpha 2-adrenergic receptors in the action of CRL 40 028 on the exocrine pancreas secretion of rats. PMID:6139981

  19. Changes in individual rates of pancreatic enzyme and isoenzyme biosynthesis in the obese Zucker rat.

    PubMed Central

    Trimble, E R; Rausch, U; Kern, H F

    1987-01-01

    Both alterations of enzyme content and a markedly decreased secretory response to selected physiological stimuli have been demonstrated previously in the pancreas of the obese Zucker rat. The purpose of the present investigation was to determine the degree to which alterations of enzyme content could be attributed to changes in enzyme biosynthesis. Amylase content of obese rats was decreased by 50%, whereas lipase and trypsinogens were significantly increased. However, the decrease in amylase content was less than might have been predicted from the rate of amylase biosynthesis (80% decrease), and the increases in content of trypsinogen(s) and lipase were greater than would have been predicted from alterations in the absolute rates of biosynthesis. In view of the rapid turnover of pancreatic enzymes under normal conditions, it seems probable that a markedly decreased secretory response to various stimuli leads to an increased content of some enzymes in the pancreas of the obese rat. Ciglitazone treatment, which decreases insulin resistance in obese animals and leads to normalization of glucose metabolism in their pancreatic tissue, restored the enzyme-synthesis rates towards normal, showing that the abnormalities of enzyme synthesis were linked to the insulin resistance rather than to the obese genotype itself. Lipid inclusion bodies were found in acinar cells of obese rats. These bodies have previously been described in acinar cells of starved animals, which, in common with the acinar tissue of the obese Zucker rat, have decreased glucose metabolism. Images Fig. 1. Fig. 3. Fig. 4. PMID:3325041

  20. Autoantibodies to the GLUT-2 glucose transporter of beta cells in insulin-dependent diabetes mellitus of recent onset.

    PubMed Central

    Inman, L R; McAllister, C T; Chen, L; Hughes, S; Newgard, C B; Kettman, J R; Unger, R H; Johnson, J H

    1993-01-01

    Purified immunoglobulin G (IgG) from the serum of patients with insulin-dependent diabetes mellitus (IDDM) of recent onset inhibits high-Km uptake of 3-O-methyl-beta-D-glucose by rat pancreatic islets. To determine if the inhibition is the result of antibodies against GLUT-2, the high-Km glucose transporter of beta cells, we incubated IDDM sera with rat islet cells and with AtT-20ins cells transfected to express GLUT-2. IDDM sera inhibited glucose uptake in islet cells and in GLUT-2-expressing AtT-20ins cells but not in AtT-20ins cells transfected to express the low-Km isoform, GLUT-1. In 24 of 30 (77%) patients with newly diagnosed IDDM, IgG binding as measured by immunofluorescence and flow cytometry of the cells transfected to express GLUT-2 was > 2 standard deviations from the mean of the nondiabetic population; 29 of 31 (96%) of nondiabetic children were negative (P < 0.0001). Increased IgG binding could be removed by absorption with GLUT-2-expressing cells but not with GLUT-1-expressing cells. We conclude that most patients with IDDM of recent onset have autoantibodies to GLUT-2. PMID:8433987

  1. Blockade of bradykinin B2 receptor suppresses acute pancreatitis induced by obstruction of the pancreaticobiliary duct in rats

    PubMed Central

    Hirata, Mitsuhiro; Hayashi, Izumi; Yoshimura, Kuniko; Ishii, Ken-ichiro; Soma, Kazui; Ohwada, Takashi; Kakita, Akira; Majima, Masataka

    2002-01-01

    The involvement of bradykinin (BK) B2 receptor in acute pancreatitis induced by pancreaticobiliary duct ligation was investigated in rats.The activities of amylase and lipase in the serum, the water content of the pancreas, and vacuolization of the acinar cells were significantly increased 2 h after obstruction of the duct in Sprague-Dawley rats.Elevated serum amylase activity, increased pancreatic oedema, and damage of the pancreatic tissue were significantly less marked in plasma kininogen-deficient, B/N-Katholiek rats than in the normal strain, B/N-Kitasato rats 2 h after the ligation.Obstruction of the pancreaticobiliary duct augmented the level of (1-5)-BK (Arg1-Pro2-Pro3-Gly4-Phe5), a stable BK metabolite, in the blood from 73.0±21.7 pg ml−1 at 0 h to 149.8±38.0 pg ml−1 at 2 h after the induction of pancreatitis in SD rats.Administration of a BK B2 receptor antagonist, FR173657 (100 mg kg−1, p.o.) or Hoe140 (100 nmol kg−1, s.c.), reduced the elevation of amylase and lipase activities in the serum and of pancreatic water content in a dose-dependent manner. The effective attenuation of oedema formation and vacuolization by the antagonists was also confirmed light-microscopically. In contrast, treatment with gabexate mesilate or indomethacin did not cause significant suppression of the pancreatitis.These findings suggest a possible involvement of kinin B2 receptor in the present pancreatitis model. Furthermore, they point to the potential usefulness of the B2 receptor in clinical acute pancreatitis. PMID:11786477

  2. A human beta cell line with drug inducible excision of immortalizing transgenes

    PubMed Central

    Benazra, Marion; Lecomte, Marie-José; Colace, Claire; Müller, Andreas; Machado, Cécile; Pechberty, Severine; Bricout-Neveu, Emilie; Grenier-Godard, Maud; Solimena, Michele; Scharfmann, Raphaël; Czernichow, Paul; Ravassard, Philippe

    2015-01-01

    Objectives Access to immortalized human pancreatic beta cell lines that are phenotypically close to genuine adult beta cells, represent a major tool to better understand human beta cell physiology and develop new therapeutics for Diabetes. Here we derived a new conditionally immortalized human beta cell line, EndoC-βH3 in which immortalizing transgene can be efficiently removed by simple addition of tamoxifen. Methods We used lentiviral mediated gene transfer to stably integrate a tamoxifen inducible form of CRE (CRE-ERT2) into the recently developed conditionally immortalized EndoC βH2 line. The resulting EndoC-βH3 line was characterized before and after tamoxifen treatment for cell proliferation, insulin content and insulin secretion. Results We showed that EndoC-βH3 expressing CRE-ERT2 can be massively amplified in culture. We established an optimized tamoxifen treatment to efficiently excise the immortalizing transgenes resulting in proliferation arrest. In addition, insulin expression raised by 12 fold and insulin content increased by 23 fold reaching 2 μg of insulin per million cells. Such massive increase was accompanied by enhanced insulin secretion upon glucose stimulation. We further observed that tamoxifen treated cells maintained a stable function for 5 weeks in culture. Conclusions EndoC βH3 cell line represents a powerful tool that allows, using a simple and efficient procedure, the massive production of functional non-proliferative human beta cells. Such cells are close to genuine human beta cells and maintain a stable phenotype for 5 weeks in culture. PMID:26909308

  3. Tissue-Specific Methylation of Human Insulin Gene and PCR Assay for Monitoring Beta Cell Death

    PubMed Central

    Husseiny, Mohamed I.; Kaye, Alexander; Zebadua, Emily; Kandeel, Fouad; Ferreri, Kevin

    2014-01-01

    The onset of metabolic dysregulation in type 1 diabetes (T1D) occurs after autoimmune destruction of the majority of pancreatic insulin-producing beta cells. We previously demonstrated that the DNA encoding the insulin gene is uniquely unmethylated in these cells and then developed a methylation-specific PCR (MSP) assay to identify circulating beta cell DNA in streptozotocin-treated mice prior to the rise in blood glucose. The current study extends to autoimmune non-obese diabetic (NOD) mice and humans, showing in NOD mice that beta cell death occurs six weeks before the rise in blood sugar and coincides with the onset of islet infiltration by immune cells, demonstrating the utility of MSP for monitoring T1D. We previously reported unique patterns of methylation of the human insulin gene, and now extend this to other human tissues. The methylation patterns of the human insulin promoter, intron 1, exon 2, and intron 2 were determined in several normal human tissues. Similar to our previous report, the human insulin promoter was unmethylated in beta cells, but methylated in all other tissues tested. In contrast, intron 1, exon 2 and intron 2 did not exhibit any tissue-specific DNA methylation pattern. Subsequently, a human MSP assay was developed based on the methylation pattern of the insulin promoter and human islet DNA was successfully detected in circulation of T1D patients after islet transplantation therapy. Signal levels of normal controls and pre-transplant samples were shown to be similar, but increased dramatically after islet transplantation. In plasma the signal declines with time but in whole blood remains elevated for at least two weeks, indicating that association of beta cell DNA with blood cells prolongs the signal. This assay provides an effective method to monitor beta cell destruction in early T1D and in islet transplantation therapy. PMID:24722187

  4. Damage to pancreatic acinar cells and preservation of islets of Langerhans in a rat model of acute pancreatitis induced by Karwinskia humboldtiana (buckthorn).

    PubMed

    Carcano-Diaz, Katya; Garcia-Garcia, Aracely; Segoviano-Ramirez, Juan Carlos; Rodriguez-Rocha, Humberto; Loera-Arias, Maria de Jesus; Garcia-Juarez, Jaime

    2016-09-01

    Karwinskia humboldtiana (Kh) is a poisonous plant that grows in some regions of the American continent. Consuming large amounts of Kh fruit results in acute intoxication leading to respiratory failure, culminating in death within days. There is evidence of histological damage to the lungs, liver, and kidneys following accidental and experimental Kh intoxication. To date, the microscopic effect of Kh consumption on the pancreas has not been described. We examined the early effects of Kh fruit on pancreatic tissue at different stages of acute intoxication in the Wistar rat. We found progressive damage confined to the exocrine pancreas, starting with a reduction in the number of zymogen granules, loss of acinar architecture, the presence of autophagy-like vesicles, apoptosis and inflammatory infiltrate. The pancreatic pathology culminated in damaged acini characterized by necrosis and edema, with a complete loss of lobular architecture. Interestingly, the morphology of the islets of Langerhans was conserved throughout our evaluations. Taken together, our results indicate the damage induced by a high dose of Kh fruit in the Wistar rat is consistent with an early acute necrotizing pancreatitis that exclusively affects the exocrine pancreas. Therefore, this system might be useful as an animal model to study the treatment of pancreatic diseases. More importantly, as the islets of Langerhans were preserved, the active compounds of Kh fruit could be utilized for the treatment of acinar pancreatic cancer. Further studies might provide insight into the severity of acute Kh intoxication in humans and influence the design of treatments for pancreatic diseases and acinar pancreatic cancer. PMID:26877198

  5. Acetaldehyde inhibition of protein synthesis in isolated rat pancreatic acini

    SciTech Connect

    Majumdar, A.P.; Haiman, M.J.; Zylbert, B.A.; Billy, H.T.; Vesenka, G.D.; Geokas, M.C.

    1986-03-30

    Exposure of isolated dispersed pancreatic acini to increasing concentrations of ethanol (5 to 500 mM) or acetaldehyde (0.5 to 100 mM) produced a progressive inhibition of (3H)leucine incorporation into both cellular (those remaining in the cell) and secretory (those released into the medium) proteins. Whereas 500 mM ethanol caused 90-95% inhibition in the synthesis of cellular and secretory proteins, the concentration of acetaldehyde needed to produce a similar inhibition was found to be 50 mM. All subsequent experiments were performed with 12.5 mM acetaldehyde, a concentration that consistently inhibited acinar protein synthesis by about 50%. The acetaldehyde-mediated inhibition of acinar protein synthesis was partially normalized when this metabolite was removed after 30 min during a 90-min incubation period. In the presence of acetaldehyde, the secretion of 3H-pulse-labeled proteins, but not amylase, trypsinogen, or chymotrypsinogen, was greatly depressed. Acetaldehyde also caused a marked reduction in (3H)uridine incorporation into acinar RNA. The entry of (3H)uridine, (3H)leucine, and (3H)aminoisobutyric acid into isolated acini was found to be slightly (15-25%) decreased by acetaldehyde. It is concluded that acetaldehyde exerts a direct toxic effect on isolated dispersed pancreatic acini as evidenced by diminution of both protein and RNA synthesis and decreased secretion of the newly synthesized proteins. This inhibitory effect of acetaldehyde could be partially reversed.

  6. Rhinacanthin C ameliorates hyperglycaemia, hyperlipidemia and pancreatic destruction in streptozotocin-nicotinamide induced adult male diabetic rats.

    PubMed

    Adam, Siti Hajar; Giribabu, Nelli; Rao, Pasupuleti Visweswara; Sayem, Abu Sadat Md; Arya, Aditya; Panichayupakaranant, Pharkphoom; Korla, Praveen Kumar; Salleh, Naguib

    2016-01-15

    Effect of Rhinacanthin C on hyperglycaemia, hyperlipidemia and pancreatic dysfunction in diabetes was investigated. In-vitro effect of Rhinacanthin C on glucose uptake was studied in 3T3-L1 cell line. Meanwhile, in-vivo effect of 28-days treatment with 5mg/kg/day or 20mg/kg/day Rhinacanthin C was studied in streptozotocin-nicotinamide induced male diabetic rats. Following completion of treatment, fasting blood glucose (FBG), HbA1c, insulin and lipid profile levels were measured by biochemical assays. Histopathological changes in pancreas were observed by light microscopy while levels of pancreatic oxidative stress were determined by enzymatic assays. Expression of insulin, TNFα, Ikkβ and caspase-3 in pancreas were quantified by immunohistochemistry. Molecular docking was used to identify interactions between Rhinacathin C with SOD or GPx enzymes. Dose-dependent increase in glucose uptake was observed with increasing doses of Rhinacathin C. Plasma FBG, HbA1c and lipid profile except LDL levels and pancreatic malonaldehyde level were reduced but serum insulin and pancreatic anti-oxidative enzymes (SOD, CAT and GPx) levels were increased in diabetic rats receiving Rhinacanthin C treatment. Decreased pancreatic histopathological changes with higher pancreatic insulin and Glut-2 levels but lower TNFα, Ikkβ and caspase-3 levels were observed in diabetic rats receiving Rhinacanthin C (P<0.05 compared to non-treated diabetic rats). In diabetic rats which received Rhinacathin C, changes in the above parameters did not achieve the value in non-diabetic rats. Docking shows Rhinacathin C possesses high degree interactions with SOD and GPx. By possessing these effects, Rhinacanthin C could be used as agent to alleviate pancreatic and other complications in diabetes. PMID:26703866

  7. Hepatic steatosis depresses alpha-1-antitrypsin levels in human and rat acute pancreatitis

    PubMed Central

    Wang, Qian; Du, Jianjun; Yu, Pengfei; Bai, Bin; Zhao, Zhanwei; Wang, Shiqi; Zhu, Junjie; Feng, Quanxin; Gao, Yun; Zhao, Qingchuan; Liu, Chaoxu

    2015-01-01

    Hepatic steatosis (HS) can exacerbate acute pancreatitis (AP). This study aimed to investigate the relation between α1-antitrypsin (AAT) and acute pancreatitis when patients have HS. Using proteomic profiling, we identified 18 differently expressed proteins pots in the serum of rats with or without HS after surgical establishment of AP. AAT was found to be one of the significantly down-regulated proteins. AAT levels were significantly lower in hepatic steatosis acute pancreatitis (HSAP) than in non-HSAP (NHSAP) (P < 0.001). To explore the clinical significance of these observations, we measured the levels of AAT in the serum of 240 patients with HSAP, NHSAP, fatty liver disease (FLD), or no disease. Compared with healthy controls, serum AAT levels in patients with NHSAP were significantly higher (P < 0.01), while in patients with HSAP serum AAT levels were significantly lower (P < 0.01). Further studies showed that acute physiology and chronic health evaluation (APACHE-II) scores were negatively correlated with serum AAT levels (r = −0.85, P < 0.01). In conclusion, low serum levels of AAT in patients with HSAP are correlated with disease severity and AAT may represent a potential target for therapies aiming to improve pancreatitis. PMID:26634430

  8. Hepatic steatosis depresses alpha-1-antitrypsin levels in human and rat acute pancreatitis.

    PubMed

    Wang, Qian; Du, Jianjun; Yu, Pengfei; Bai, Bin; Zhao, Zhanwei; Wang, Shiqi; Zhu, Junjie; Feng, Quanxin; Gao, Yun; Zhao, Qingchuan; Liu, Chaoxu

    2015-01-01

    Hepatic steatosis (HS) can exacerbate acute pancreatitis (AP). This study aimed to investigate the relation between α1-antitrypsin (AAT) and acute pancreatitis when patients have HS. Using proteomic profiling, we identified 18 differently expressed proteins pots in the serum of rats with or without HS after surgical establishment of AP. AAT was found to be one of the significantly down-regulated proteins. AAT levels were significantly lower in hepatic steatosis acute pancreatitis (HSAP) than in non-HSAP (NHSAP) (P < 0.001). To explore the clinical significance of these observations, we measured the levels of AAT in the serum of 240 patients with HSAP, NHSAP, fatty liver disease (FLD), or no disease. Compared with healthy controls, serum AAT levels in patients with NHSAP were significantly higher (P < 0.01), while in patients with HSAP serum AAT levels were significantly lower (P < 0.01). Further studies showed that acute physiology and chronic health evaluation (APACHE-II) scores were negatively correlated with serum AAT levels (r = -0.85, P < 0.01). In conclusion, low serum levels of AAT in patients with HSAP are correlated with disease severity and AAT may represent a potential target for therapies aiming to improve pancreatitis. PMID:26634430

  9. Efficient gene delivery to pancreatic islets with ultrasonic microbubble destruction technology

    NASA Astrophysics Data System (ADS)

    Chen, Shuyuan; Ding, Jia-Huan; Bekeredjian, Raffi; Yang, Bing-Zhi; Shohet, Ralph V.; Johnston, Stephen A.; Hohmeier, Hans E.; Newgard, Christopher B.; Grayburn, Paul A.

    2006-05-01

    This study describes a method of gene delivery to pancreatic islets of adult, living animals by ultrasound targeted microbubble destruction (UTMD). The technique involves incorporation of plasmids into the phospholipid shell of gas-filled microbubbles, which are then infused into rats and destroyed within the pancreatic microcirculation with ultrasound. Specific delivery of genes to islet beta cells by UTMD was achieved by using a plasmid containing a rat insulin 1 promoter (RIP), and reporter gene expression was regulated appropriately by glucose in animals that received a RIP-luciferase plasmid. To demonstrate biological efficacy, we used UTMD to deliver RIP-human insulin and RIP-hexokinase I plasmids to islets of adult rats. Delivery of the former plasmid resulted in clear increases in circulating human C-peptide and decreased blood glucose levels, whereas delivery of the latter plasmid resulted in a clear increase in hexokinase I protein expression in islets, increased insulin levels in blood, and decreased circulating glucose levels. We conclude that UTMD allows relatively noninvasive delivery of genes to pancreatic islets with an efficiency sufficient to modulate beta cell function in adult animals. diabetes | gene therapy | ultrasound

  10. Efficient gene delivery to pancreatic islets with ultrasonic microbubble destruction technology

    PubMed Central

    Chen, Shuyuan; Ding, Jia-huan; Bekeredjian, Raffi; Yang, Bing-zhi; Shohet, Ralph V.; Johnston, Stephen A.; Hohmeier, Hans E.; Newgard, Christopher B.; Grayburn, Paul A.

    2006-01-01

    This study describes a method of gene delivery to pancreatic islets of adult, living animals by ultrasound targeted microbubble destruction (UTMD). The technique involves incorporation of plasmids into the phospholipid shell of gas-filled microbubbles, which are then infused into rats and destroyed within the pancreatic microcirculation with ultrasound. Specific delivery of genes to islet beta cells by UTMD was achieved by using a plasmid containing a rat insulin 1 promoter (RIP), and reporter gene expression was regulated appropriately by glucose in animals that received a RIP–luciferase plasmid. To demonstrate biological efficacy, we used UTMD to deliver RIP–human insulin and RIP–hexokinase I plasmids to islets of adult rats. Delivery of the former plasmid resulted in clear increases in circulating human C-peptide and decreased blood glucose levels, whereas delivery of the latter plasmid resulted in a clear increase in hexokinase I protein expression in islets, increased insulin levels in blood, and decreased circulating glucose levels. We conclude that UTMD allows relatively noninvasive delivery of genes to pancreatic islets with an efficiency sufficient to modulate beta cell function in adult animals. PMID:16709667

  11. Morphometric measurements to quantify the cerulein induced hyperstimulatory pancreatitis of rats under the protective effect of lectins.

    PubMed

    Jonas, L; Mikkat, U; Witte, A; Beckmann, U; Dölker, K; Weber, H; Hahnel, C; Kundt, G; Nizze, H

    1998-01-01

    In preceding papers we demonstrated an inhibitory effect of wheat germ agglutinin (WGA) and Ulex europaeus agglutinin (UEA) on the cholecystokinin (CCK) binding to the CCK receptor of rat pancreatic cells and also on the CCK induced Ca2+ release and alpha-amylase secretion in vitro as well as on pancreatic secretion of intact rats in vivo. In the present study we show the same inhibitory effect of both lectins on the cerulein pancreatitis of rats. This acute pancreatitis was induced by supramaximal injections (5 microg/kg/h i.v. or 10 microg/kg/h i.p.) of the CCK analogue cerulein in rats every hour. To monitor the degree of pancreatitis, we measured the number and diameter of injury vacuoles in the pancreatic acinar cells as one of the most important signs of this type of pancreatitis by light microscopic morphometry with two different systems on paraffin sections. Furthermore, the serum alpha-amylase activity was measured biochemically. We found a correlation between the diameter of vacuoles inside the acinar cells and the serum enzyme activity up to 24 h. The simultaneous i.p. administration of cerulein and WGA or UEA in a dosage of 125 microg/kg/h for 8 h led to a reduction of vacuolar diameter from 13.1+/-2.0 microm (cerulein) to 7.5+/-1.1 microm (cerulein + WGA) or 7.2+/-1.3 microm (cerulein + UEA). The serum amylase activity was reduced from 63.7+/-15.8 mmol/l x min (cerulein) to 37.7+/-11.8 (cerulein + WGA) or 39.4; +52.9; -31.1 (cerulein + UEA-I). Both parameters allow the grading this special type of pancreatitis to demonstrate the protective effect of the lectins. PMID:10391374

  12. Thyrotropin-releasing hormone (TRH) reverses hyperglycemia in rat

    SciTech Connect

    Luo Luguang Luo, John Z.Q. Jackson, Ivor M.D.

    2008-09-12

    Hyperglycemia in thyrotropin-releasing hormone (TRH) null mice indicates that TRH is involved in the regulation of glucose homeostasis. Further, TRH levels in the pancreas peak during the stages of late embryonic and early neonatal {beta} cell development. These observations are consistent in linking TRH to islet cell proliferation and differentiation. In this study, we examined the effect of TRH administration in damaged pancreatic rat (streptozotocin, STZ) to determine whether TRH could improve damaged pancreatic {beta} cells function. We hypothesize that TRH is able to reverse STZ-induced hyperglycemia by increasing pancreatic islet insulin content, preventing apoptosis, and potentially induce islet regeneration. It was found that following intra-peritoneal (ip) injection, TRH (10 {mu}g/kg body weight (bwt)) reverses STZ (65 mg/kg bwt)-induced hyperglycemia (TRH given 3 days after STZ injection). Increased circulating insulin levels and insulin content in extracted pancreas suggests that TRH reversed STZ-induced hyperglycemia through improving pancreatic islet {beta} cell function. Further studies show a significantly lower level of apoptosis in islets treated with TRH as well as the presence of proliferation marker nestin and Brdu, suggesting that the TRH has the potential to prevent apoptosis and stimulate islet proliferation.

  13. Coating nanofiber scaffolds with beta cell membrane to promote cell proliferation and function

    NASA Astrophysics Data System (ADS)

    Chen, Wansong; Zhang, Qiangzhe; Luk, Brian T.; Fang, Ronnie H.; Liu, Younian; Gao, Weiwei; Zhang, Liangfang

    2016-05-01

    The cell membrane cloaking technique has emerged as an intriguing strategy in nanomaterial functionalization. Coating synthetic nanostructures with natural cell membranes bestows the nanostructures with unique cell surface antigens and functions. Previous studies have focused primarily on development of cell membrane-coated spherical nanoparticles and the uses thereof. Herein, we attempt to extend the cell membrane cloaking technique to nanofibers, a class of functional nanomaterials that are drastically different from nanoparticles in terms of dimensional and mechanophysical characteristics. Using pancreatic beta cells as a model cell line, we demonstrate successful preparation of cell membrane-coated nanofibers and validate that the modified nanofibers possess an antigenic exterior closely resembling that of the source beta cells. When such nanofiber scaffolds are used to culture beta cells, both cell proliferation rate and function are significantly enhanced. Specifically, glucose-dependent insulin secretion from the cells is increased by near five-fold compared with the same beta cells cultured in regular, unmodified nanofiber scaffolds. Overall, coating cell membranes onto nanofibers could add another dimension of flexibility and controllability in harnessing cell membrane functions and offer new opportunities for innovative applications.

  14. Coating nanofiber scaffolds with beta cell membrane to promote cell proliferation and function.

    PubMed

    Chen, Wansong; Zhang, Qiangzhe; Luk, Brian T; Fang, Ronnie H; Liu, Younian; Gao, Weiwei; Zhang, Liangfang

    2016-05-21

    The cell membrane cloaking technique has emerged as an intriguing strategy in nanomaterial functionalization. Coating synthetic nanostructures with natural cell membranes bestows the nanostructures with unique cell surface antigens and functions. Previous studies have focused primarily on development of cell membrane-coated spherical nanoparticles and the uses thereof. Herein, we attempt to extend the cell membrane cloaking technique to nanofibers, a class of functional nanomaterials that are drastically different from nanoparticles in terms of dimensional and mechanophysical characteristics. Using pancreatic beta cells as a model cell line, we demonstrate successful preparation of cell membrane-coated nanofibers and validate that the modified nanofibers possess an antigenic exterior closely resembling that of the source beta cells. When such nanofiber scaffolds are used to culture beta cells, both cell proliferation rate and function are significantly enhanced. Specifically, glucose-dependent insulin secretion from the cells is increased by near five-fold compared with the same beta cells cultured in regular, unmodified nanofiber scaffolds. Overall, coating cell membranes onto nanofibers could add another dimension of flexibility and controllability in harnessing cell membrane functions and offer new opportunities for innovative applications. PMID:27139582

  15. Specific Silencing of the REST Target Genes in Insulin-Secreting Cells Uncovers Their Participation in Beta Cell Survival

    PubMed Central

    Gesina, Emilie; Caille, Dorothee; Gjinovci, Asllan; Waeber, Gerard; Meda, Paolo; Haefliger, Jacques-Antoine

    2012-01-01

    The absence of the transcriptional repressor RE-1 Silencing Transcription Factor (REST) in insulin-secreting beta cells is a major cue for the specific expression of a large number of genes. These REST target genes were largely ascribed to a function of neurotransmission in a neuronal context, whereas their role in pancreatic beta cells has been poorly explored. To identify their functional significance, we have generated transgenic mice expressing REST in beta cells (RIP-REST mice), and previously discovered that REST target genes are essential to insulin exocytosis. Herein we characterized a novel line of RIP-REST mice featuring diabetes. In diabetic RIP-REST mice, high levels of REST were associated with postnatal beta cell apoptosis, which resulted in gradual beta cell loss and sustained hyperglycemia in adults. Moreover, adenoviral REST transduction in INS-1E cells led to increased cell death under control conditions, and sensitized cells to death induced by cytokines. Screening for REST target genes identified several anti-apoptotic genes bearing the binding motif RE-1 that were downregulated upon REST expression in INS-1E cells, including Gjd2, Mapk8ip1, Irs2, Ptprn, and Cdk5r2. Decreased levels of Cdk5r2 in beta cells of RIP-REST mice further confirmed that it is controlled by REST, in vivo. Using siRNA-mediated knock-down in INS-1E cells, we showed that Cdk5r2 protects beta cells against cytokines and palmitate-induced apoptosis. Together, these data document that a set of REST target genes, including Cdk5r2, is important for beta cell survival. PMID:23029270

  16. Specific silencing of the REST target genes in insulin-secreting cells uncovers their participation in beta cell survival.

    PubMed

    Martin, David; Allagnat, Florent; Gesina, Emilie; Caille, Dorothee; Gjinovci, Asllan; Waeber, Gerard; Meda, Paolo; Haefliger, Jacques-Antoine

    2012-01-01

    The absence of the transcriptional repressor RE-1 Silencing Transcription Factor (REST) in insulin-secreting beta cells is a major cue for the specific expression of a large number of genes. These REST target genes were largely ascribed to a function of neurotransmission in a neuronal context, whereas their role in pancreatic beta cells has been poorly explored. To identify their functional significance, we have generated transgenic mice expressing REST in beta cells (RIP-REST mice), and previously discovered that REST target genes are essential to insulin exocytosis. Herein we characterized a novel line of RIP-REST mice featuring diabetes. In diabetic RIP-REST mice, high levels of REST were associated with postnatal beta cell apoptosis, which resulted in gradual beta cell loss and sustained hyperglycemia in adults. Moreover, adenoviral REST transduction in INS-1E cells led to increased cell death under control conditions, and sensitized cells to death induced by cytokines. Screening for REST target genes identified several anti-apoptotic genes bearing the binding motif RE-1 that were downregulated upon REST expression in INS-1E cells, including Gjd2, Mapk8ip1, Irs2, Ptprn, and Cdk5r2. Decreased levels of Cdk5r2 in beta cells of RIP-REST mice further confirmed that it is controlled by REST, in vivo. Using siRNA-mediated knock-down in INS-1E cells, we showed that Cdk5r2 protects beta cells against cytokines and palmitate-induced apoptosis. Together, these data document that a set of REST target genes, including Cdk5r2, is important for beta cell survival. PMID:23029270

  17. Protective efficacy of folic acid and vitamin B12 against nicotine-induced toxicity in pancreatic islets of the rat

    PubMed Central

    Bhattacharjee, Ankita; Prasad, Shilpi Kumari; Pal, Swagata; Maji, Bithin; Syamal, Alak Kumar; Banerjee, Arnab

    2015-01-01

    Although cigarette smoking is associated with insulin resistance and an increased risk for type 2 diabetes, few studies have examined the effect of nicotine on the adult endocrine pancreas. In this study, male Wister rats were treated with nicotine (3 mg/kg body weight/ day) with or without supplementation of folic acid (36 μg/kg body weight/day) or vitamin B12 (0.63 μg/kg body weight/day) alone or in combination. Fasting blood glucose, insulin and HBA1C level and different oxidative and anti-oxidative stress parameters were measured and pancreatic tissue sections were stained with eosin-haematoxylene. Data were analysed by nonparametric statistics. The results revealed that nicotine induced prediabetes condition with subsequent damage to pancreatic islets in rats. Nicotine also caused oxidative stress in pancreatic tissue as evidenced by increased nitric oxide and malondialdehyde level and decreased superoxide dismutase, catalase and reduced glutathione level. Compared to vitamin B12 supplementation, folic acid blunted the nicotine-induced toxicity in pancreatic islets with higher efficacy. Further, folic acid and vitamin B12 in combination were able to confer significant protection on pancreatic islets against nicotine induced toxicity. These results suggest that supplementation of folic acid and vitamin B12 in combination may be a possible strategy of detoxification against nicotine-induced toxicity in pancreatic islets of the rat. PMID:27486368

  18. Protective effect of Mimosa pudica L. in an L-arginine model of acute necrotising pancreatitis in rats.

    PubMed

    Kaur, Jagdeep; Sidhu, Shabir; Chopra, Kanwaljit; Khan, M U

    2016-07-01

    Mimosa pudica is used in traditional medicine for treating various disorders such as inflammatory conditions, diarrhoea, insomnia, alopecia, urogenital infections and wounds. The present study investigated the effect of M. pudica extract (MPE) on L-arginine-induced acute necrotising pancreatitis in rats. The ethanolic extract of M. pudica leaves was studied for the presence of quercetin and gallic acid using high-performance liquid chromatography. Four groups were employed-normal control rats, L-arginine control rats (two intraperitoneal [i.p.] injections of 2 g/kg at an interval of 1 h), MPE-treated rats (400 mg/kg orally) and melatonin-treated rats (positive control 10 mg/kg i.p.), which were further divided into subgroups according to time points (24 h, 3 days and 14 days). Serum amylase, lipase, tumour necrosis factor-α (TNF-α), pancreatic amylase, nucleic acid content, protein, transforming growth factor-β1 (TGF-β1), thiobarbituric reactive substances, glutathione, nitrite/nitrate, collagen content and histopathological examination were carried out. MPE significantly improved acute necrotising pancreatitis by modulating diagnostic markers of pancreatitis such as serum lipase and pancreatic amylase, inflammation (TNF-α), and oxidative and nitrosative stress. Moreover, MPE administration induced regenerative changes in the pancreas evidenced by increased levels of pancreatic proteins, nucleic acid content and histopathology report. In addition, MPE improved TGF-β1 and collagen levels thereby preventing fibrosis. The current investigation indicates the novel role of MPE in reducing the severity of acute necrotising pancreatitis by plausible mechanisms such as anti-inflammatory and anti-fibrotic activity and by promoting repair and regeneration of the pancreas. PMID:27164910

  19. Protective effects of sivelestat in a caerulein-induced rat acute pancreatitis model.

    PubMed

    Cao, Jun; Liu, Quanyan

    2013-12-01

    In the present study, we investigated the protective effects of sivelestat on acute pancreatitis (AP) in a rat model. Sivelestat is a specific neutrophil elastase inhibitor, which has been developed in Japan in 1991. Varying doses of sivelestat in normal saline were infused continuously in sivelestat-treated groups through osmotic pumps. Blood and pancreas samples were collected for serological and histopathological studies, and ten rats in each group were taken for survival observation. Increasing doses of sivelestat inhibits the expression of lipase, amylase, corticosterone, IL-1β, TNF-α, and nuclear factor-κB. Furthermore, sivelestat reduces the inflammatory cells infiltration, histological damage, and mortality rate. Meanwhile, the total antioxidant power and serum level of IL-4 in high-dose sivelestat-treated groups were increased. Our findings suggest that the increasing doses of sivelestat protect against caerulein-induced AP in rats, and this protection is possibly associated with the anti-inflammatory ability of sivelestat. PMID:23794035

  20. Transient cytokine treatment induces acinar cell reprogramming and regenerates functional beta cell mass in diabetic mice

    PubMed Central

    Baeyens, Luc; Lemper, Marie; Leuckx, Gunter; De Groef, Sofie; Bonfanti, Paola; Stangé, Geert; Shemer, Ruth; Nord, Christoffer; Scheel, David W.; Pan, Fong C.; Ahlgren, Ulf; Gu, Guoqiang; Stoffers, Doris A.; Dor, Yuval; Ferrer, Jorge; Gradwohl, Gerard; Wright, Christopher VE; Van de Casteele, Mark; German, Michael S.; Bouwens, Luc; Heimberg, Harry

    2014-01-01

    Reprogramming of pancreatic exocrine cells into cells resembling beta cells may provide a strategy for treating diabetes. Here we show that transient administration of epidermal growth factor and ciliary neurotrophic factor to adult mice with chronic hyperglycemia efficiently stimulates the conversion of terminally differentiated acinar cells to beta-like cells. Newly generated beta-like cells are epigenetically reprogrammed, functional and glucose-responsive, and reinstate normal glycemic control for up to 248 days. The regenerative process depends on Stat3 signaling and requires a threshold number of Neurogenin 3 (Ngn3) expressing acinar cells. In contrast to previous work demonstrating in vivo conversion of acinar cells to beta-like cells by viral delivery of exogenous transcription factors, our approach achieves acinar-to-beta cell reprogramming through transient cytokine exposure rather than genetic modification. PMID:24240391

  1. Can we make surrogate beta-cells better than the original?

    PubMed

    Weir, Gordon C

    2004-06-01

    Insufficient pancreatic beta-cell mass is fundamental to the pathogenesis of both types 1 and 2 diabetes and constitutes the basis for the goal of beta-cell replacement therapy. Current methods for isolating islets from organ donor pancreases do not come close to supplying all in need, thus providing a compelling need to find new sources of insulin-producing cells. Possible sources include generation of cells from embryonic stem cells (ESC), adult stem/precursor cells, transdifferentiation of other cell types and xenodonors. Bioengineering can be used to improve secretory performance and strengthen cells to better withstand the challenges of transplantation. Strategies include protection against hypoxia, inflammation, and immune attack. PMID:15125898

  2. Restructuring of Pancreatic Islets and Insulin Secretion in a Postnatal Critical Window

    PubMed Central

    Aguayo-Mazzucato, Cristina; Sanchez-Soto, Carmen; Godinez-Puig, Victoria; Gutiérrez-Ospina, Gabriel; Hiriart, Marcia

    2006-01-01

    Function and structure of adult pancreatic islets are determined by early postnatal development, which in rats corresponds to the first month of life. We analyzed changes in blood glucose and hormones during this stage and their association with morphological and functional changes of alpha and beta cell populations during this period. At day 20 (d20), insulin and glucose plasma levels were two- and six-fold higher, respectively, as compared to d6. Interestingly, this period is characterized by physiological hyperglycemia and hyperinsulinemia, where peripheral insulin resistance and a high plasmatic concentration of glucagon are also observed. These functional changes were paralleled by reorganization of islet structure, cell mass and aggregate size of alpha and beta cells. Cultured beta cells from d20 secreted the same amount of insulin in 15.6 mM than in 5.6 mM glucose (basal conditions), and were characterized by a high basal insulin secretion. However, beta cells from d28 were already glucose sensitive. Understanding and establishing morphophysiological relationships in the developing endocrine pancreas may explain how events in early life are important in determining adult islet physiology and metabolism. PMID:17183663

  3. Phosphorylation events implicating p38 and PI3K mediate tungstate-effects in MIN6 beta cells

    SciTech Connect

    Piquer, Sandra; Gomis, Ramon . E-mail: rgomis@clinic.ub.es

    2007-06-29

    Oral administration of sodium tungstate is an effective treatment for diabetes in animal models. Several lines of evidence indicate the pancreatic beta cell as one of the targets of tungstate action. Here, we examined the molecular mechanism by which this compound exerts its effects on the beta cell line MIN6. Tungstate treatment induced phosphorylation and subsequent activation of p38 and PI3K which in turn are implicated in tungstate PDX-1 nuclear localization and activation. Although no effect was observed in glucose-induced insulin secretion we found that tungstate activates basal insulin release, a process driven, at least in part, by activation of p38. These results show a direct involvement of p38 and PI3K phosphorylation in the mechanism of action of tungstate in the beta cell.

  4. Protective and curative effects of Cocos nucifera inflorescence on alloxan-induced pancreatic cytotoxicity in rats

    PubMed Central

    Renjith, Raveendran S.; Rajamohan, Thankappan

    2012-01-01

    Objectives: This study was planned to investigate the effects of pre and post-treatment of young inflorescence of Cocos nucifera (CnI) on alloxan-induced diabetic rats. Materials and Methods: Male albino Sprague Dawely rats were divided into five groups of six animals each. Group I was normal control, Group II was diabetic control, Cocos nucifera Inflorescence (CnI) was fed along with diet [20% (w/w)] orally (Group III) for a period of 11 days prior to alloxan injection (150 mg/kg i.p.). The curative effect of CnI was evaluated at the same feeding levels in alloxan-induced diabetic rats (Group IV) for a period of 30 days. The effects of both pretreatment and post-treatment (Group V) were also evaluated. Biochemical parameters such serum glucose, hepatic glycogen, and enzymes involving carbohydrate metabolism (hexokinase, phosphoglucomutase, pyruvate kinase, glucose-6-phosphatase, fructose 1, 6-diphosphatase, glucose-6 phosphate dehydrogenase, and glycogen phosphorylase) were assayed along with pancreatic histopathology. Data were analyzed using one-way analysis of variance followed by Duncan's post hoc multiple variance test. P < 0.05 was considered statistical significant. Results: Diabetic control rats showed significant increase in serum glucose (P < 0.05) and decrease in hepatic glycogen levels (P < 0.05) compared to normal rats, which was reversed to near normal in both CnI pretreated and post-treated rats. Treatment with CnI resulted in significant decrease (P < 0.05) in activities of gluconeogenic enzymes in Group III and IV on compared to the diabetic control group, while glycolytic enzyme activities were improved in these groups. The cytotoxicity of pancreatic islets also ameliorated by treatment with CnI on histopathological examination. Conclusion: The results obtained in the study indicate the protective and curative effects of CnI on alloxan-induced pancreatic cytotoxicity, which is mediated through the regulation of carbohydrate metabolic enzyme

  5. The antioxidant effect of angiotensin II receptor blocker, losartan, in streptozotocin-induced diabetic rats.

    PubMed

    Kamper, Maria; Tsimpoukidi, Olia; Chatzigeorgiou, Antonios; Lymberi, Maria; Kamper, Elli F

    2010-07-01

    We determined the effect of a short-term angiotensin II signaling blockade on vascular endothelial growth factor (VEGF), soluble intercellular adhesion molecule-1 (sICAM-1), nitric oxide (NO), and malondialdehyde (MDA) (index of lipid peroxidation) levels in the systemic circulation and on peroxynitrite generation and insulitis development in the streptozotocin (STZ) diabetic rats' pancreas. Diabetes was induced in Wistar rats by intraperitoneal STZ injection. Diabetic rats were treated for 1 week with losartan (20 mg/kg/body weight/day in the drinking water), and pancreas and blood were collected for histochemical, immunohistochemical, and biochemical studies. Diabetic rats showed greater VEGF, sICAM-1, NO, and MDA levels, a high score of insulitis, increased nitrotyrosine staining, and markedly reduced pancreatic insulin content when compared with controls. Losartan treatment suppressed the excessive NO and lipid peroxidation production systemically without restoring them to that of healthy subjects and reduced VEGF levels while leaving sICAM-1 levels unchanged. The insulitis score and nitrotyrosine staining were reduced, whereas the pancreatic islets and the beta-cell area were increased significantly in the treated group, indicating the reduction of inflammation and nitrosative stress and an early regeneration of beta-cell mass in the pancreas. Conclusively, in the STZ diabetic rat model, even a short-term losartan treatment improves oxidative and nitrosative stress systemically and locally, improving the islets' environment and accelerating beta-cell regeneration. PMID:20621034

  6. Mangiferin from Salacia chinensis prevents oxidative stress and protects pancreatic β-cells in streptozotocin-induced diabetic rats.

    PubMed

    Sellamuthu, Periyar Selvam; Arulselvan, Palanisamy; Muniappan, Balu Periamallipatti; Fakurazi, Sharida; Kandasamy, Murugesan

    2013-08-01

    Oxidative stress in diabetic tissues is a consequence of free radical accumulation with concurrently impaired natural antioxidants status and results in oxidative tissue damage. The present study investigated the protective effects of mangiferin against pancreatic β-cell damage and on the antioxidant defense systems in streptozotocin (STZ)-induced diabetic rats. Diabetes was experimentally induced by a single intraperitoneal injection of STZ. Oxidative stress biomarkers such as tissue malondialdehyde, hydroperoxides, reduced glutathione (GSH) content, and nonenzymatic antioxidants were measured. Biochemical observations were further substantiated with histological examination and ultrastructural studies in the pancreas of diabetic, glibenclamide and mangiferin-treated diabetic rats (dosage of 40 mg/kg body weight daily for 30 days). Oral administration of mangiferin and glibenclamide to diabetic rats significantly decreased the level of blood glucose and increased levels of insulin. Additionally, mangiferin treatment significantly modulated the pancreatic nonenzymatic antioxidants status (vitamin C, vitamin E, ceruloplasmin, and reduced GSH content) and other oxidative stress biomarkers. The histoarchitecture of diabetic rats showed degenerated pancreas with lower β-cell counts, but mangiferin treatment effectively regenerated insulin secreting islet cells. The electron microscopic study revealed damaged nuclear envelope and mitochondria and fewer secretory granules in pancreas of diabetic rats; however, mangiferin treatment nearly normalized pancreatic architecture. The present findings suggest that mangiferin treatment exerts a therapeutic protective nature in diabetes by decreasing oxidative stress and protecting against pancreatic β-cell damage, which may be attributable to its antioxidative properties. PMID:23957355

  7. Effect of tiron on remote organ injury in rats with severe acute pancreatitis induced by L-arginine.

    PubMed

    Ateyya, Hayam; Wagih, Heba M; El-Sherbeeny, Nagla A

    2016-08-01

    Acute pancreatitis (AP) is an acute inflammatory disorder of the pancreas that can be complicated by involvement of other remote organs. Oxidative stress is known to have a crucial role in the development of pancreatic acinar damage and one of the main causes in multisystem organ failure in experimental AP. The aim of the study was to determine the effect of tiron on pancreas and remote organ damage in L-arginine (L-Arg) induced AP rat model. Thirty-two male rats were divided in random into four groups: control, tiron, L-Arg, and tiron with L-Arg. At the end of the experiment, blood samples were withdrawn for biochemical analysis. The pancreas, lung, kidney, and liver were collected for histopathological examination. Estimation of pancreatic water content was done. Analysis of pulmonary, hepatic, renal, and pancreatic lipid peroxide levels (MDA), superoxide dismutase (SOD), and reduced glutathione (GSH) were carried out. Finally, nuclear factor kappa B (NF-κB) and transforming growth factor β1 (TGF-β1) expression in pancreatic tissue was determined. Results indicated that treatment with tiron significantly decreased lipid peroxide levels and markedly increased both SOD activity and GSH level. Moreover, histopathological analysis further confirmed that administration of tiron relatively ameliorates pancreatic acinar cells and remote organ damage. Increased immunoreactivity of NF-κB and TGF-β1 were reduced also by tiron treatment. These findings pointed out the protective role of the mitochondrial antioxidant, tiron against AP induced by L-Arg. PMID:27118662

  8. Cocaine- and Amphetamine-regulated Transcript (CART) Protects Beta Cells against Glucotoxicity and Increases Cell Proliferation*

    PubMed Central

    Sathanoori, Ramasri; Olde, Björn; Erlinge, David; Göransson, Olga; Wierup, Nils

    2013-01-01

    Cocaine- and amphetamine-regulated transcript (CART) is an islet peptide that promotes glucose-stimulated insulin secretion in beta cells via cAMP/PKA-dependent pathways. In addition, CART is a regulator of neuronal survival. In this study, we examined the effect of exogenous CART 55–102 on beta cell viability and dissected its signaling mechanisms. Evaluation of DNA fragmentation and chromatin condensation revealed that CART 55–102 reduced glucotoxicity-induced apoptosis in both INS-1 (832/13) cells and isolated rat islets. Glucotoxicity in INS-1 (832/13) cells also caused a 50% reduction of endogenous CART protein. We show that CART increased proliferation in INS-1 (832/13) cells, an effect that was blocked by PKA, PKB, and MEK1 inhibitors. In addition, CART induced phosphorylation of CREB, IRS, PKB, FoxO1, p44/42 MAPK, and p90RSK in INS-1 (832/13) cells and isolated rat islets, all key mediators of cell survival and proliferation. Thus, we demonstrate that CART 55-102 protects beta cells against glucotoxicity and promotes proliferation. Taken together our data point to the potential use of CART in therapeutic interventions targeted at enhancing functional beta cell mass and long-term insulin secretion in T2D. PMID:23250745

  9. Cocaine- and amphetamine-regulated transcript (CART) protects beta cells against glucotoxicity and increases cell proliferation.

    PubMed

    Sathanoori, Ramasri; Olde, Björn; Erlinge, David; Göransson, Olga; Wierup, Nils

    2013-02-01

    Cocaine- and amphetamine-regulated transcript (CART) is an islet peptide that promotes glucose-stimulated insulin secretion in beta cells via cAMP/PKA-dependent pathways. In addition, CART is a regulator of neuronal survival. In this study, we examined the effect of exogenous CART 55-102 on beta cell viability and dissected its signaling mechanisms. Evaluation of DNA fragmentation and chromatin condensation revealed that CART 55-102 reduced glucotoxicity-induced apoptosis in both INS-1 (832/13) cells and isolated rat islets. Glucotoxicity in INS-1 (832/13) cells also caused a 50% reduction of endogenous CART protein. We show that CART increased proliferation in INS-1 (832/13) cells, an effect that was blocked by PKA, PKB, and MEK1 inhibitors. In addition, CART induced phosphorylation of CREB, IRS, PKB, FoxO1, p44/42 MAPK, and p90RSK in INS-1 (832/13) cells and isolated rat islets, all key mediators of cell survival and proliferation. Thus, we demonstrate that CART 55-102 protects beta cells against glucotoxicity and promotes proliferation. Taken together our data point to the potential use of CART in therapeutic interventions targeted at enhancing functional beta cell mass and long-term insulin secretion in T2D. PMID:23250745

  10. Differential effects of three echovirus strains on cell lysis and insulin secretion in beta cell derived lines.

    PubMed

    Sarmiento, Luis; Medina, Anya; Aziz, Kosrat; Anagandula, Mahesh; Cabrera-Rode, Eduardo; Fex, Malin; Frisk, Gun; Cilio, Corrado M

    2016-06-01

    In an earlier study, infection of human pancreatic islets with epidemic strains of echovirus (E4, E16, E30), with proven but differently ability to induce islet autoimmunity, resulted either in a severe damage (i.e., E16 and E30) or proceeded without visible changes in infected islets (i.e., E4). In this study, the ability of these strains to replicate in beta cells and the consequence of such an infection for beta cell lysis and beta cell function was studied in the pancreatic beta cell lines INS-1, MIN6, and NIT-1. The strains of E16 and E30 did replicate in INS1, MIN6, and NIT1 cells and resulted in a pronounced cytopathic effect within 3 days following infection. By contrast, E4 replicated in all examined insulinoma cells with no apparent cell destruction. The insulin release in response to high glucose stimulation was hampered in all infected cells (P < 0.05) when no evidence of cytolysis was present; however, the adverse effect of E16 and E30 on insulin secretion appeared to be higher than that of the E4 strain. The differential effects of echovirus infection on cell lysis, and beta cell function in the rodent insulinoma INS1, MIN6, and NIT 1 cells reflect those previously obtained in primary human islets and support the notion that the insulin-producing beta cells can harbor a non-cytopathic viral infection. J. Med. Virol. 88:971-978, 2016. © 2015 Wiley Periodicals, Inc. PMID:26629879

  11. Quantitative functional MRI in a clinical orthotopic model of pancreatic cancer in immunocompetent Lewis rats

    PubMed Central

    Zhang, Zhuoli; Zheng, Linfeng; Li, Weiguo; Gordon, Andrew C; Huan, Yi; Shangguan, Junjie; Procissi, Daniel; Bentrem, David J; Larson, Andrew C

    2015-01-01

    Objective: To demonstrate feasibility of performing quantitative MRI measurements in an immuno-competent rat model of pancreatic cancer by comparing in vivo anatomic and quantitative imaging measurements to tumor dissemination observations and histologic assays at necropsy. Meterials and methods: Rat ductal pancreatic adenocarcinoma DSL-6A/C1 cell line and Lewis rats were used for these studies. 108 DSL-6A/C1 cells were injected subcutaneously into the right flank of donor rats. Donor tumors reaching 10 mm were excised, and 1 mm3 tumor fragments were implanted within recipient rat pancreas during mini-laparotomy. T1-weighted, T2-weighted, diffusion-weighted, and dynamic contrast-enhanced (DCE) MRI were performed using a Bruker 7.0T ClinScan. After MRI, all animals underwent autopsy. Primary tumor size was measured, and dissemination score was used to assess local invasion and distant metastasis. Primary tumor and all sites of metastases were harvested and fixed for H&E, Masson’s trichrome, and rat anti-CD34 staining. Trichrome slides were scanned and digitized for measurement of fibrotic tissue areas. Anti-CD34 slides were used for microvessel density (MVD) measurements. Results: Primary tumors, local invasion, and distant metastases were confirmed for all rats. No significant differences were found between in vivo MRI measurements (48.7 ± 5.3 mm) and ex vivo caliper measurements (43.6 ± 3.6 mm) of primary tumor sizes (p > .05). Spleen, liver, diaphragm, peritoneum, and abdominal wall metastases were observed on MRI but smaller lung, mediastinum, omen, and mesentery metastases were only observed at necropsy. Contrast uptake observed during DCE measurements was significantly greater in both primary and metastatic tumor tissues compared to skeletal muscle and normal liver tissues. Both primary and metastatic tumors were hyper-intense in T2-weighted images and hypo-intense in T1-weighted images, but no differences were found between quantitative T2 measurements in

  12. Rosiglitazone attenuates the severity of hyperlipidemic severe acute pancreatitis in rats

    PubMed Central

    NIYAZ, BATUR; ZHAO, KAI-LIANG; LIU, LI-MIN; CHEN, CHEN; DENG, WEN-HONG; ZUO, TENG; SHI, QIAO; WANG, WEI-XING

    2013-01-01

    Peroxisome proliferator-activated receptor-γ (PPAR-γ) ligand regulates adipocyte differentiation and insulin sensitivity, and exerts antihyperlipidemic and anti-inflammatory effects. However, the mechanisms by which PPAR-γ ligands affect hyperlipidemia with severe acute pancreatitis (SAP) have not been fully elucidated. The present study investigated the effects of rosiglitazone, a PPAR-γ ligand, on hyperlipidemia with SAP in a rat model. The hyperlipidemia was induced with a high-fat diet and SAP was induced by the administration of sodium taurocholate (TCA). The hyperlipidemia was shown to aggravate the severity of the sodium taurocholate-induced SAP. However, rosiglitazone demonstrated significant antihyperlipidemic and anti-inflammatory effects in the rats with high-lipid diet-induced hyperlipidemia and SAP. PMID:24137303

  13. Lapacho tea (Tabebuia impetiginosa) extract inhibits pancreatic lipase and delays postprandial triglyceride increase in rats.

    PubMed

    Kiage-Mokua, Beatrice Nyanchama; Roos, Nils; Schrezenmeir, Jürgen

    2012-12-01

    Earlier work in our laboratory indicated that ethanolic extracts of Tabebuia impetiginosa, Arctium lappa L., Calendula officinalis, Helianthus annuus, Linum usitatissimum and L. propolis, inhibit pancreatic lipase in vitro. In a follow-up study we assessed their effects on plasma triglycerides in rats fed on a fatty meal. Extracts, orlistat or only ethanol were given orally to the rats together with the test meal and the rate of increase of postprandial triglycerides was assessed over 4 h. Clearing of the triglycerides from the blood compartment was abolished by inhibiting lipoprotein lipase with Triton WR-1339. Our results showed that out of all the extracts, the bark of Tabebuia impetiginosa led to a significant delay in the postprandial increase of plasma triglycerides. However, lapachol, which is contained in the bark of Tabebuia impetiginosa and soluble in ethanol, had no lipase inhibitory effect in vitro and hence this substance did not seem to mediate the pertinent effect. PMID:22431070

  14. Pancreatic B-cell behaviour after changing the natural environment of sand rats (Psammomys obesus.

    PubMed

    Hahn, H J; Jutzi, E; Köhler, E; Schäfer, H

    1976-01-01

    On the basis of the blood glucose increase during the capitivity sand rats born in the desert were classified as normals, protodiabetics and diabetics, indicating a different adaptation to the new environment within a definite period. Isolated islets of animals, which did not develop a hyperglycemia, enhanced their insulin content during the adaptation period. The absolute insulin secretion rates in response to 16.5 mM glucose were rather similar between the three investigated groups and not modified by the insulin as well as glucagon content of pancreatic islets. But, since islets of hyperglycemic sand rats could not increase the insulin content, a significantly enhanced fractional secretion (as % of the content) could be observed. The results let us assume that the B-cell reaction during the adaptation period can be modified by further factors additionally to the changed environment. PMID:795642

  15. Hydrogen-rich saline ameliorates the severity of L-arginine-induced acute pancreatitis in rats

    SciTech Connect

    Chen, Han; Sun, Yan Ping; Li, Yang; Liu, Wen Wu; Xiang, Hong Gang; Fan, Lie Ying; Sun, Qiang; Xu, Xin Yun; Cai, Jian Mei; Ruan, Can Ping; Su, Ning; Yan, Rong Lin; Sun, Xue Jun; Wang, Qiang

    2010-03-05

    Molecular hydrogen, which reacts with the hydroxyl radical, has been considered as a novel antioxidant. Here, we evaluated the protective effects of hydrogen-rich saline on the L-arginine (L-Arg)-induced acute pancreatitis (AP). AP was induced in Sprague-Dawley rats by giving two intraperitoneal injections of L-Arg, each at concentrations of 250 mg/100 g body weight, with an interval of 1 h. Hydrogen-rich saline (>0.6 mM, 6 ml/kg) or saline (6 ml/kg) was administered, respectively, via tail vein 15 min after each L-Arg administration. Severity of AP was assessed by analysis of serum amylase activity, pancreatic water content and histology. Samples of pancreas were taken for measuring malondialdehyde and myeloperoxidase. Apoptosis in pancreatic acinar cell was determined with terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling technique (TUNEL). Expression of proliferating cell nuclear antigen (PCNA) and nuclear factor kappa B (NF-{kappa}B) were detected with immunohistochemistry. Hydrogen-rich saline treatment significantly attenuated the severity of L-Arg-induced AP by ameliorating the increased serum amylase activity, inhibiting neutrophil infiltration, lipid oxidation and pancreatic tissue edema. Moreover, hydrogen-rich saline treatment could promote acinar cell proliferation, inhibit apoptosis and NF-{kappa}B activation. These results indicate that hydrogen treatment has a protective effect against AP, and the effect is possibly due to its ability to inhibit oxidative stress, apoptosis, NF-{kappa}B activation and to promote acinar cell proliferation.

  16. Ethnic differences in insulin sensitivity and beta-cell function among Asian men

    PubMed Central

    Tan, V M H; Lee, Y S; Venkataraman, K; Khoo, E Y H; Tai, E S; Chong, Y S; Gluckman, P; Leow, M K S; Khoo, C M

    2015-01-01

    Background and objectives: Lean Asian Indians are less insulin sensitive compared with Chinese and Malays, but the pancreatic beta-cell function among these ethnic groups has yet to be studied in depth. We aimed to study beta-cell function in relation to insulin sensitivity among individuals of Chinese, Malay and Asian-Indian ethnicity living in Singapore. Subjects and methods: This is a sub-group analysis of 59 normoglycemic lean (body mass index (BMI) <23 kg m−2) adult males (14 Chinese, 21 Malays and 24 Asian Indians) from the Singapore Adults Metabolism Study. Insulin sensitivity was determined using fasting state indices (homeostatic model assessment—insulin resistance), the euglycemic-hyperinsulinemic clamp (ISI-clamp) and a liquid mixed-meal tolerance test (LMMTT) (Matsuda insulin sensitivity index (ISI-Mat)). Beta-cell function was assessed using fasting state indices (homeostatic model assessment—beta-cell function) and from the LMMTT (insulinogenic index and insulin secretion index). The oral disposition index (DI), a measure of beta-cell function relative to insulin sensitivity during the LMMTT, was calculated as a product of ISI-Mat and insulin secretion index. Results: Asian Indians had higher waist circumference and percent body fat than Chinese and Malays despite similar BMI. Overall, Asian Indians were the least insulin sensitive whereas the Chinese were most insulin sensitive. Asian Indians had higher beta-cell function compared with Chinese or Malays but these were not statistically different. Malays had the highest incremental area under the curve for glucose during LMMTT compared with Asian Indians and Chinese. However, there were no significant ethnic differences in the incremental insulin area under the curve. The oral DI was the lowest in Malays, followed by Asian Indians and Chinese. Conclusion: Among lean Asians, Chinese are the most insulin sensitive whereas Asian Indians are the least insulin sensitive. However, Malays

  17. Carvacrol modulates oxidative stress and decreases cell injury in pancreas of rats with acute pancreatitis.

    PubMed

    Kılıç, Yeliz; Geyikoglu, Fatime; Çolak, Suat; Turkez, Hasan; Bakır, Murat; Hsseinigouzdagani, Mirkhalil

    2016-08-01

    Acute pancreatitis (AP) is considered as major problem around the world and the incidence of AP is increasing. Carvacrol (CAR), a monoterpenic phenol, has good antioxidant activity. This in vivo study was designed to evaluate whether CAR provide protection against AP that developed by pancreas injury. The rats were randomised into groups to receive (I) no therapy; (II) 50 µg/kg cerulein at 1 h intervals by four intraperitonally (i.p.) injections; (III) 50, 100 and 200 mg/kg CAR by one i.p. injection; and (IV) cerulein plus CAR after 2 h of cerulein administration. 12 h later, serum samples were obtained to assess pancreatic function, the lipase and amylase values. The oxidative stress markers were evaluated by changes in the amount of lipid peroxides measured as malondialdehyde (MDA) and changes in main tissue antioxidant enzyme levels including SOD, CAT and GSH-PX. Histopathological examination was performed using scoring systems. Additionally, oxidative DNA damage was determined by measuring the increases of 8-hydroxy-deoxyguanosine (8-OH-dG) formations. We found that the increasing doses of CAR decreased AP-induced MDA and 8-OH-dG levels. Moreover, the pancreas antioxidant enzyme activities were higher than that of the rats in the AP group when compared to the AP plus CAR group. In the treatment groups, the lipase and amylase were reduced. Besides, histopathological findings in the pancreatic tissue were alleviated (p < 0.05). We suggest that CAR could be a safe and potent new drug candidate for treating AP through its antioxidative mechanism of action for the treatment of a wide range of disorders related to pancreas. PMID:26093481

  18. Beneficial Antioxidative and Antiperoxidative Effect of Cinnamaldehyde Protect Streptozotocin-Induced Pancreatic β-Cells Damage in Wistar Rats

    PubMed Central

    Subash-Babu, P.; Alshatwi, Ali A.; Ignacimuthu, S.

    2014-01-01

    The present study was aimed to evaluate the antioxidant defense system of cinnamaldehyde in normal, diabetic rats and its possible protection of pancreatic β-cells against its gradual loss under diabetic conditions. In vitro free radical scavenging effect of cinnamaldehyde was determined using DPPH (1,1-diphenyl-2-dipicrylhydrazyl), superoxide radical, and nitric oxide radical. Streptozotocin (STZ) diabetic rats were orally administered with cinnamaldehyde at concentrations of 5, 10 and 20 mg/kg body weight for 45 days. At the end of the experiment, the levels of plasma lipid peroxides and antioxidants such as vitamin C, vitamin E, ceruloplasmin, catalase, superoxide dismutase, reduced glutathione and glutathione peroxidase were determined. A significant increase in the levels of plasma glucose, vitamin E, ceruloplasmin, and lipid peroxides and significant decrease in the levels of plasma insulin and reduced glutathione were observed in the diabetic rats. Also the activities of pancreatic antioxidant enzymes were altered in the STZ-induced diabetic rats. The altered enzyme activities were reverted to near-normal levels after treatment with cinnamaldehyde and glibenclamide. Histopathological studies also revealed a protective effect of cinnamaldehyde on pancreatic β-cells. Cinnamaldehyde enhances the antioxidant defense against reactive oxygen species produced under hyperglycemic conditions and thus protects pancreatic β-cells against their loss and exhibits antidiabetic properties. PMID:24596621

  19. Rosmarinic Acid Attenuates Sodium Taurocholate-Induced Acute Pancreatitis in Rats by Inhibiting Nuclear Factor-κB Activation.

    PubMed

    Fan, Yu-Ting; Yin, Guo-Jian; Xiao, Wen-Qin; Qiu, Lei; Yu, Ge; Hu, Yan-Ling; Xing, Miao; Wu, De-Qing; Cang, Xiao-Feng; Wan, Rong; Wang, Xing-Peng; Hu, Guo-Yong

    2015-01-01

    Rosmarinic Acid (RA), a caffeic acid ester, has been shown to exert anti-inflammation, anti-oxidant and antiallergic effects. Our study aimed to investigate the effect of RA in sodium taurocholate ( NaTC )-induced acute pancreatitis, both in vivo and in vitro. In vivo, RA (50 mg/kg) was administered intraperitoneally 2 h before sodium taurocholate injection. Rats were sacrificed 12 h, 24 h or 48 h after sodium taurocholate injection. Pretreatment with RA significantly ameliorated pancreas histopathological changes, decreased amylase and lipase activities in serum, lowered myeloperoxidase activity in the pancreas, reduced systematic and pancreatic interleukin-1 β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) levels, and inhibited NF-κB translocation in pancreas. In vitro, pretreating the fresh rat pancreatic acinar cells with 80 μ mol/L RA 2 h before 3750 nmol/L sodium taurocholate or 10 ng/L TNF-α administration significantly attenuated the reduction of isolated pancreatic acinar cell viability and inhibited the nuclear activation and translocation of NF-κB. Based on our findings, RA appears to attenuate damage in sodium taurocholate-induced acute pancreatitis and reduce the release of inflammatory cytokines by inhibiting the activation of NF-κB. These findings might provide a basis for investigating the therapeutic role of RA in managing acute pancreatits. PMID:26364660

  20. Nanomaterial Solutions for the Protection of Insulin Producing Beta Cells

    NASA Astrophysics Data System (ADS)

    Atchison, Nicole Ann

    Islet transplantation is a promising treatment for type 1 diabetes. However, even with the many successes, islet transplantation has yet to reach its full potential. Limited islet sources, loss of cell viability during isolation and culture, and post-transplant graft loss are a few of the issues preventing extensive use of islet transplantation. The application of biomaterial systems to alleviate some of the stresses affecting islet viability has led to improvements in isolation and transplantation outcomes, but problems persist. In this work we approach two distinct issues affecting islet viability; ischemic conditions and immunological attack post-transplant. Ischemic conditions have been linked to a loss of islet graft function and occur during organ preservation, islet isolation and culture, and after islets are transplanted. We show that liposomal delivery of adenosine triphosphate (ATP) to beta cells can limit cell death and loss of function in ischemic conditions. We demonstrate that by functionalizing liposomes with the fibronectin-mimetic peptide PR_b, delivery of liposomes to porcine islets and rat beta cells is increased compared to nontargeted controls. Additionally, liposomes are shown to protect by providing both ATP and lipids to the ischemic cells. The delivery of ATP was investigated here but application of PR_b functionalized liposomes could be extended to other interesting cargos as well. The second area of investigation involves encapsulation of islets with silica nanoparticles to create a permselective barrier. Silica nanoparticles are an interesting material for encapsulation given their ability to be fine-tuned and further functionalized. We demonstrate that size-tunable, fluorescent silica nanoparticles can be assembled layer-by-layer on the surface of cells and that silica nanoparticle encapsulated islets are able to secrete insulin in response to a glucose challenge.

  1. GeneSpeed Beta Cell: An Online Genomics Data Repository and Analysis Resource Tailored for the Islet Cell Biologist

    PubMed Central

    Quayum, Nayeem; Kutchma, Alecksandr; Sarkar, Suparna A.; Juhl, Kirstine; Gradwohl, Gerard; Mellitzer, Georg; Hutton, John C.; Jensen, Jan

    2008-01-01

    Objective. We here describe the development of a freely available online database resource, GeneSpeed Beta Cell, which has been created for the pancreatic islet and pancreatic developmental biology investigator community. Research Design and Methods. We have developed GeneSpeed Beta Cell as a separate component of the GeneSpeed database, providing a genomics-type data repository of pancreas and islet-relevant datasets interlinked with the domain-oriented GeneSpeed database. Results. GeneSpeed Beta Cell allows the query of multiple published and unpublished select genomics datasets in a simultaneous fashion (multiexperiment viewing) and is capable of defining intersection results from precomputed analysis of such datasets (multidimensional querying). Combined with the protein-domain categorization/assembly toolbox provided by the GeneSpeed database, the user is able to define spatial expression constraints of select gene lists in a relatively rigid fashion within the pancreatic expression space. We provide several demonstration case studies of relevance to islet cell biology and development of the pancreas that provide novel insight into islet biology. Conclusions. The combination of an exhaustive domain-based compilation of the transcriptome with gene array data of interest to the islet biologist affords novel methods for multidimensional querying between individual datasets in a rapid fashion, presently not available elsewhere. PMID:18795106

  2. Long-term aspirin pretreatment in the prevention of cerulein-induced acute pancreatitis in rats

    PubMed Central

    Akyazi, Ibrahim; Eraslan, Evren; Gülçubuk, Ahmet; Ekiz, Elif Ergül; Çırakli, Zeynep L; Haktanir, Damla; Bala, Deniz Aktaran; Özkurt, Mete; Matur, Erdal; Özcan, Mukaddes

    2013-01-01

    AIM: To investigate the effects of long term pretreatment with low-, medium- and high-dose aspirin (acetylsalicylic acid, ASA) on a model of acute pancreatitis (AP) induced in rats. METHODS: Forty male Wistar rats were used. Three experimental groups, each consisting of eight animals, received low- (5 mg/kg per day), medium- (150 mg/kg per day) and high-dose (350 mg/kg per day) ASA in supplemented pellet chow for 100 d. Eight animals, serving as the AP-control group, and another eight, serving as reference value (RV) group, were fed with standard pellet chow for the same period. After pretreatment, AP was induced in the experimental animals by intraperitoneal administration of cerulein (2 × 50 μg/kg), while the RV group received saline in the same way. Twelve hours after the second injection, the animals were sacrificed. Pancreatic tissue and plasma samples were collected. One part of the collected pancreatic tissues was used for histopathological evaluation, and the remaining portion was homogenized. Cytokine levels [tumor necrosis factor, interleukin (IL)-1β, IL-6], hemogram parameters, biochemical parameters (amylase and lipase), nuclear factor-κB, aspirin triggered lipoxins and parameters related to the antioxidant system (malondialdehyde, nitric oxide, hemeoxygenase-1, catalase and superoxide dismutase) were measured. RESULTS: Cerulein administration induced mild pancreatitis, characterized by interstitial edema (total histopathological score of 5.88 ± 0.44 vs 0.25 ± 0.16, P < 0.001). Subsequent pancreatic tissue damage resulted in an increase in amylase (2829.71 ± 772.48 vs 984.57 ± 49.22 U/L, P = 0.001) and lipase (110.14 ± 75.84 U/L vs 4.71 ± 0.78 U/L, P < 0.001) in plasma, and leucocytes (6.89 ± 0.48 vs 4.36 ± 0.23, P = 0.001) in peripheral blood. Cytokines, IL-1β (18.81 ± 2.55 pg/μg vs 6.65 ± 0.24 pg/μg, P = 0.002) and IL-6 (14.62 ± 1.98 pg/μg vs 9.09 ± 1.36 pg/μg, P = 0.04) in pancreatic tissue also increased. Aspirin pretreatment

  3. Neuromedin U receptor 1 expression in the rat endocrine pancreas and evidence suggesting neuromedin U suppressive effect on insulin secretion from isolated rat pancreatic islets.

    PubMed

    Kaczmarek, Przemyslaw; Malendowicz, Ludwik K; Pruszynska-Oszmalek, Ewa; Wojciechowicz, Tatiana; Szczepankiewicz, Dawid; Szkudelski, Tomasz; Nowak, Krzysztof W

    2006-11-01

    Neuromedin U (NmU) is a regulatory peptide found in significant concentrations in both the brain and gut of the rat and is named according to its ability to powerfully contract the uterus. Two types of NmU receptors were recently identified and subsequent studies evidenced NmU involvement in the regulation of energy homeostasis. Such a role of neuromedin U suggests that a polypeptide may also be involved in the regulation of adipoinsular axis function. Therefore in the present study we examined the expression of NmU receptors in pancreatic islets using RT-PCR and Western blotting analysis. We also investigated the role of NmU in regulation of insulin secretion in vitro using isolated pancreatic islets. We have confirmed that NmUR1 but not NmUR2 is specifically expressed in isolated rat pancreatic islets. In all tested doses (1, 10, 100 nmol/l) NmU dose- dependently decreased insulin output by isolated pancreatic islets. These inhibitory effects of NmU on insulin secretion may suggest the involvement of NmU in regulating the pancreatic branch of adipoinsular axis function. Thus, NmU can be included in that group of anorectic peptides, which are also involved in the regulation of insulin secretion. PMID:17016626

  4. Differences between Human and Rodent Pancreatic Islets

    PubMed Central

    MacDonald, Michael J.; Longacre, Melissa J.; Stoker, Scott W.; Kendrick, Mindy; Thonpho, Ansaya; Brown, Laura J.; Hasan, Noaman M.; Jitrapakdee, Sarawut; Fukao, Toshiyuki; Hanson, Matthew S.; Fernandez, Luis A.; Odorico, Jon

    2011-01-01

    Anaplerosis, the net synthesis in mitochondria of citric acid cycle intermediates, and cataplerosis, their export to the cytosol, have been shown to be important for insulin secretion in rodent beta cells. However, human islets may be different. We observed that the enzyme activity, protein level, and relative mRNA level of the key anaplerotic enzyme pyruvate carboxylase (PC) were 80–90% lower in human pancreatic islets compared with islets of rats and mice and the rat insulinoma cell line INS-1 832/13. Activity and protein of ATP citrate lyase, which uses anaplerotic products in the cytosol, were 60–75% lower in human islets than in rodent islets or the cell line. In line with the lower PC, the percentage of glucose-derived pyruvate that entered mitochondrial metabolism via carboxylation in human islets was only 20–30% that in rat islets. This suggests human islets depend less on pyruvate carboxylation than rodent models that were used to establish the role of PC in insulin secretion. Human islets possessed high levels of succinyl-CoA:3-ketoacid-CoA transferase, an enzyme that forms acetoacetate in the mitochondria, and acetoacetyl-CoA synthetase, which uses acetoacetate to form acyl-CoAs in the cytosol. Glucose-stimulated human islets released insulin similarly to rat islets but formed much more acetoacetate. β-Hydroxybutyrate augmented insulin secretion in human islets. This information supports previous data that indicate beta cells can use a pathway involving succinyl-CoA:3-ketoacid-CoA transferase and acetoacetyl-CoA synthetase to synthesize and use acetoacetate and suggests human islets may use this pathway more than PC and citrate to form cytosolic acyl-CoAs. PMID:21454710

  5. G protein in stimulation of PI hydrolysis by CCK (cholecystokinin) in isolated rat pancreatic acinar cells

    SciTech Connect

    Matozaki, Takashi; Sakamoto, Choitsu; Nagao, Munehiko; Nishizaki, Hogara; Baba, Shigeaki )

    1988-11-01

    To clarify the possible role of a guanine nucleotide-binding protein (G protein) in the signal transducing system activated by cholecystokinin (CCK), actions of CCK on rat pancreatic acini were compared with those of fluoride, a well-known activator of stimulatory (G{sub s}) or inhibitory (G{sub i}) G protein. When acini were incubated with increasing concentrations of either CCK-octapeptide (CCK8) or NaF, a maximal stimulation of amylase release from acini occurred at 100 pM CCK8 or 10 mM NaF, respectively; this secretory rate decreased as CCK8 or NaF concentration was increased. NaF caused an increase in cytoplasmic Ca{sup 2+} concentration from the internal Ca{sup 2+} store and stimulated accumulation of inositol phosphates in acini, as observed with CCK. Guanylimidodiphosphate activated the generation of inositol phosphates in the ({sup 3}H)inositol-labeled pancreatic acinar cell membrane preparation, with half-maximal and maximal stimulation at 1 and 10 {mu}M, respectively. Furthermore, the effects of submaximal CCK concentrations on inositol phosphate accumulation in membranes were markedly potentiated in the presence of 100 {mu}M GTP, which alone was ineffective. Combined findings of the present study strongly suggest that pancreatic CCK receptors are probably coupled to the activation of polyphosphoinositide (PI) breakdown by a G protein, which appears to be fluoride sensitive but is other than G{sub s}- or G{sub i}-like protein.

  6. Prolonged stimulation of pancreatic serous secretions by bile and sodium taurocholate in anaesthetized rats.

    PubMed

    Morrison, James D

    2012-12-01

    There have been numerous reports that infusion of either natural bile or bile salts into the duodenum evokes a rapid increase in pancreatic secretion through the release of the hormone secretin from the duodenal mucosa. We have extended this observation by the demonstration of an additional late increase in secretion which persisted for many hours and have sought to identify the processes underlying this increase. In anaesthetised rats, infusion of 20 mM taurocholate into the duodenum caused a staircase-like increase in the weight of pancreatic secretion which extended over many hours during which, the HCO[Formula: see text] and protein output of the secretion showed only minimal changes. This effect was also reproduced with intra-duodenal infusion of natural bile which was inferred to act though its taurocholate content. Since the stimulatory action was also obtained with superfusion of taurocholate or natural bile onto the small intestine and by intravenous injection of taurocholate, it was concluded that taurocholate acted by being absorbed into the bloodstream and then by exerting a stimulatory action on the exocrine pancreas. This action was inhibited by puromycin (a protein synthesis inhibitor), by furosemide (a Na( + )/K( + )/2Cl(-) cotransporter inhibitor), though not by SITS (an inhibitor of Cl(-)/HCO[Formula: see text] exchange). The long lasting increase in pancreatic serous secretion would be consistent with the possible activation of gene transcription by taurocholate leading to increased activity of the Na( + )/K( + )/2Cl(-) cotransporter through which the acinar cells increased their secretions. PMID:22538870

  7. Distribution of pancreatic B cell imaging agent 99mTc-DTPA-NGN2 in the body and animal experimental research on pancreatic B cell functional imaging

    PubMed Central

    Liu, Zhi-Hua; Xie, Ying; Tang, Jun; Liu, Chun-Feng

    2016-01-01

    Purpose: To explore the feasibility of the application of 99mTc-DTPA-Nateglinide as a nuclear medicine imaging agent for evaluating pancreatic B cell function. Methods: (1) Distribution of the experiment: Forty-two mice were selected and divided into seven groups. Each mice was injected with 3.7 MBq (100 μCi) of 99mTc-DTPA-NGN2 from the vena caudalis and was sacrificed by bloodletting at five minutes, 15 minutes, 30 minutes, one hour, two hours, four hours and six hours, respectively. Then, their tissues and organs such as the heart, liver, spleen, brain, kidneys, bones, small bowels, stomach and pancreas,and blood were collected, weighted, and their radioactivity was tested. Subsequently, the percentage injection dose rate (%ID/g) per gram of tissue was calculated. (2) Imaging experiment: Thirty-five mice were selected and divided into seven groups. Each was injected with 18.5 MBq (100 μCi) of 99mTc-DTPA-NGN2 from the vena caudalis and imaging were conducted at the same time as above. (3) Forty-eight Wistar rats were attained and randomly divided into four groups. The first group served as the healthy control group, while the second, third and fourth groups were diabetic model groups induced by intraperitoneally injecting STZ at different doses. Each group was injected with 99mTc-DTPA-Nateglinide from the vena caudalis, and radiological evaluations were conducted at 30 minutes, one hour, 1.5 hours and two hours, respectively. The data obtained were estimated using a correlation comparison with the levels of insulin and immunohistochemical count of beta cells. Results: The 99mTc-DTPA-Nateglinide demonstrated good imaging in the pancreases of mice and rats, and was positively correlated to the level of insulin and the number of pancreatic beta cells. Conclusion: Pancreatic beta cell imaging using 99mTc-DTPA-Nateglinide may be a method to evaluate pancreatic beta cell function. PMID:27186309

  8. Transduction of rat pancreatic islets with pseudotyped adeno-associated virus vectors

    PubMed Central

    Craig, Anthony T; Gavrilova, Oksana; Dwyer, Nancy K; Jou, William; Pack, Stephanie; Liu, Eric; Pechhold, Klaus; Schmidt, Michael; McAlister, Victor J; Chiorini, John A; Blanchette-Mackie, E Joan; Harlan, David M; Owens, Roland A

    2009-01-01

    Background Pancreatic islet transplantation is a promising treatment for type I diabetes mellitus, but current immunosuppressive strategies do not consistently provide long-term survival of transplanted islets. We are therefore investigating the use of adeno-associated viruses (AAVs) as gene therapy vectors to transduce rat islets with immunosuppressive genes prior to transplantation into diabetic mice. Results We compared the transduction efficiency of AAV2 vectors with an AAV2 capsid (AAV2/2) to AAV2 vectors pseudotyped with AAV5 (AAV2/5), AAV8 (AAV2/8) or bovine adeno-associated virus (BAAV) capsids, or an AAV2 capsid with an insertion of the low density lipoprotein receptor ligand from apolipoprotein E (AAV2apoE), on cultured islets, in the presence of helper adenovirus infection to speed expression of a GFP transgene. Confocal microscopy and flow cytometry were used. The AAV2/5 vector was superior to AAV2/2 and AAV2/8 in rat islets. Flow cytometry indicated AAV2/5-mediated gene expression in approximately 9% of rat islet cells and almost 12% of insulin-positive cells. The AAV2/8 vector had a higher dependence on the helper virus multiplicity of infection than the AAV 2/5 vector. In addition, the BAAV and AAV2apoE vectors were superior to AAV2/2 for transducing rat islets. Rat islets (300 per mouse) transduced with an AAV2/5 vector harboring the immunosuppressive transgene, tgfβ1, retain the ability to correct hyperglycemia when transplanted into immune-deficient diabetic mice. Conclusion AAV2/5 vectors may therefore be useful for pre-treating donor islets prior to transplantation. PMID:19450275

  9. Rat monoclonal autoantibody to pancreatic islet cells recognizes a sugar sequence in paragloboside

    SciTech Connect

    Spitalnik, S.L.; Uchigata, Y.; Selata, K.F.; Tachiwaki, O.; Notkins, A.L.

    1986-05-01

    The BB rat is an experimental model of spontaneously occurring diabetes mellitus (DM). To investigate the autoimmune pathogenesis of DM, spleen cells of newly diagnosed diabetic BB rats were fused with mouse myeloma cells. Hybridomas were screened by indirect immunofluorescence (IF) and by /sup 51/Cr release assays using the RINm5F rat insulinoma cell line. One clone (E5C2) produced an IgM antibody cytotoxic for RINm5F cells but not other rat cells. By IF, neuraminidase (NASE) increased binding of E5C2 to RINm5F cells (10% to 80%). E5C2 bound specifically to normal rat and human pancreatic islets, but only after NASE treatment. Using direct immunostaining of thin-layer chromatography plates, E5C2 bound to glycolipids isolated from various tissues. With purified glycolipids E5C2 bound only to paragloboside (Gal..beta..1-4GlcNAc..beta..1-3Gal..beta..1-4Glc-cer) and higher polylactosamine containing structures. Periodate treatment or substitution of paragloboside (PG) with other sugars abolished antigenicity. By hapten-inhibition assays lactose (Gal..beta..1-4G1c) and Gal..beta..1-4GlcNAc inhibited binding but Gal..beta..1-3GlcNAc was ineffective. PG or its sialylated derivatives were not found in RINm5F cells. However, glycoproteins were found on Western blots after NASE treatment. Lactose also inhibited this E5C2 binding. Similar autoantibodies may play a role in the pathogenesis of DM.

  10. Angiotensin type 2 receptor in pancreatic islets of adult rats: a novel insulinotropic mediator

    PubMed Central

    Shao, Chunhong; Zucker, Irving H.

    2013-01-01

    In the present study, we evaluated the relative abundance of angiotensin type 2 receptor (AT2R) protein in various tissues of adult rats. We found that pancreatic islets expressed the highest AT2R protein compared with all other tissues. Accordingly, we then determined the functional significance of AT2R in the endocrine pancreas in in vivo and in vitro experiments by using angiotensin II (ANG II) alone, losartan (Los; AT1R antagonist), compound 21 (C21; AT2R agonist), and PD-123319 (PD; AT2R antagonist). Experiments carried out in rats indicated that, 1) ANG II treatment significantly increased plasma insulin concentration (1.51 ± 0.20 vs. 0.82 ± 0.14 ng/ml, n = 7, P < 0.05) in the fed state. This insulinotropic effect was further augmented by combined treatment with ANG II + Los (2.31 ± 0.25 ng/ml, n = 7, P < 0.01). C21 also elevated insulin levels (2.13 ± 0.20 ng/ml, n = 7, P < 0.01), which was completely abolished by PD. 2) ANG II impaired glucose tolerance, whereas ANG II + Los or C21 improved this function. 3) All treated rats displayed an enhanced insulin secretory response to a glucose challenge. 4) All treated rats displayed upregulated proinsulin 2 mRNA and insulin protein expression in the pancreas. In in vitro experiments using INS-1E cells and isolated rat islets, we found that AT2R activation significantly improved insulin biosynthesis and secretion. These results suggest that the AT2R functions as an insulinotropic mediator. AT2R and its downstream signaling pathways may be potential therapeutic targets for diabetes. PMID:24085035

  11. Musa sapientum with exercises attenuates hyperglycemia and pancreatic islet cells degeneration in alloxan-diabetic rats

    PubMed Central

    Akinlolu, Adelaja Abdulazeez; Salau, Bamidele A.; Ekor, Martins; Otulana, Jubril

    2015-01-01

    Aim: We tested the hypothesis that administrations of methanolic extracts of Musa sapientum sucker (MEMS) with exercises attenuated hyperglycemia in alloxan-diabetic rats. Materials and Methods: A total of 40 adult male rats were divided into equal eight groups. Normoglycemic Group A was Control. Alloxan (180 mg/kg, i.p.) was administered to rats in Groups B - H to induce diabetes. Group B (diabetic control) received physiological saline. Groups C - H received MEMS (5 mg/kg), MEMS (10 mg/kg), Glibenclamide (5 mg/kg), MEMS (5 mg/kg) + exercises, MEMS (10 mg/kg) + exercises and Exercises only, respectively. Changes in body weight, blood glucose levels (BGL) and pancreatic histology were evaluated during or at the end of experiment. Body weights and BGL of rats were expressed as mean ± standard deviation and analyzed using the statistical software program SPSS 15. Statistical comparisons were done using the Student’s t-test for unpaired samples. Differences between groups were determined as significant at P ≤ 0.05. Results: Significantly (P < 0.05) decreased bodyweight was observed in B and H compared to A and C - G. Treatment with MEMS significantly (P < 0.05) decreased elevated BGL in C and D. Hypoglycemic effect of MEMS appeared enhanced with exercises in F and G. Exercises regimen alone (H) resulted in percentage reduction in BGL lower than those of C - G. Histopathological examinations revealed normal pancreas (A), atrophied islet cells (B), hyperplasia with adequate population of islet cells (C - G), and reduced hyperplasia of islet cells (H). Conclusion: MEMS with exercises attenuated hyperglycemia in alloxan-diabetic rats. PMID:26401408

  12. Pancreatic Histology and Associated Biochemical Changes in Rats on Hind-Limb Suspension

    NASA Astrophysics Data System (ADS)

    Soulsby, Michael; Johnson, Emily; Akel, Nisreen; Agarwal, Rakhee; Gaddy, Dana; Dobretsov, Maxim; Chowdhury, Parimal

    2011-06-01

    The pancreas plays an important role in regulating many of the key endocrine hormones and digestive enzymes that are required for nutrition and survival of the organism. This study examines the pancreatic histology and associated biochemical changes in rats on hind limb suspension (HLS) after exposure to simulated microgravity. Results show that MDA and glutathione levels were significantly increased in the suspended (HLS) groups as compared to the control group. Plasma insulin levels averaged 2.43±0.32 ng/ml in the control animals and decreased significantly to 1.47±0.24 ng/ml in the suspended group. Histopathology revealed increased vacuolation, pyknosis, membrane thickening, increase of zymogen granules and increase in islets (both in size and number) in the suspended group as compared to the control group.

  13. Blockade of Multidrug Resistance-Associated Proteins Aggravates Acute Pancreatitis and Blunts Atrial Natriuretic Factor’s Beneficial Effect in Rats: Role of MRP4 (ABCC4)

    PubMed Central

    Ventimiglia, María Silvia; Najenson, Ana Clara; Perazzo, Juan Carlos; Carozzo, Alejandro; Vatta, Marcelo S; Davio, Carlos A; Bianciotti, Liliana G

    2015-01-01

    We previously reported that atrial natriuretic factor (ANF) stimulates secretin-evoked cAMP efflux through multidrug resistance-associated protein 4 (MRP4) in the exocrine pancreas. Here we sought to establish in vivo whether this mechanism was involved in acute pancreatitis onset in the rat. Rats pretreated with or without probenecid (MRPs general inhibitor) were infused with secretin alone or with ANF. A set of these animals were given repetitive cerulein injections to induce acute pancreatitis. Plasma amylase and intrapancreatic trypsin activities were measured and histological examination of the pancreas performed. Secretin alone activated trypsinogen but induced no pancreatic histological changes. Blockade by probenecid in secretin-treated rats increased trypsin and also induced vacuolization, a hallmark of acute pancreatitis. ANF prevented the secretin response but in the absence of probenecid. In rats with acute pancreatitis, pretreatment with secretin aggravated the disease, but ANF prevented secretin-induced changes. Blockade of MRPs in rats with acute pancreatitis induced trypsinogen activation and larger cytoplasmic vacuoles as well as larger areas of necrosis and edema that were aggravated by secretin but not prevented by ANF. The temporal resolution of intracellular cAMP levels seems critical in the onset of acute pancreatitis, since secretin-evoked cAMP in a context of MRP inhibition makes the pancreas prone to injury in normal rats and aggravates the onset of acute pancreatitis. Present findings support a protective role for ANF mediated by cAMP extrusion through MRP4 and further suggest that the regulation of MRP4 by ANF would be relevant to maintain pancreatic acinar cell homeostasis. PMID:25569802

  14. Matrix metalloproteinases, T cell homing and beta-cell mass in type 1 diabetes.

    PubMed

    Savinov, Alexei Y; Strongin, Alex Y

    2009-01-01

    The pathogenesis of type 1 diabetes begins with the activation of autoimmune T killer cells and is followed by their homing into the pancreatic islets. After penetrating the pancreatic islets, T cells directly contact and destroy insulin-producing beta cells. This review provides an overview of the dynamic interactions which link T cell membrane type-1 matrix metalloproteinase (MT1-MMP) and the signaling adhesion CD44 receptor with T cell transendothelial migration and the subsequent homing of the transmigrated cells to the pancreatic islets. MT1-MMP regulates the functionality of CD44 in diabetogenic T cells. By regulating the functionality of T cell CD44, MT1-MMP mediates the transition of T cell adhesion to endothelial cells to the transendothelial migration of T cells, thus, controlling the rate at which T cells home into the pancreatic islets. As a result, the T cell MT1-MMP-CD44 axis controls the severity of the disease. Inhibition of MT1-MMP proteolysis of CD44 using highly specific and potent synthetic inhibitors, which have been clinically tested in cancer patients, reduces the rate of transendothelial migration and the homing of T cells. Result is a decrease in the net diabetogenic efficiency of T cells and a restoration of beta cell mass and insulin production in NOD mice. The latter is a reliable and widely used model of type I diabetes in humans. Overall, existing experimental evidence suggests that there is a sound mechanistic rationale for clinical trials of the inhibitors of T cell MT1-MMP in human type 1 diabetes patients. PMID:19251049

  15. Fisetin averts oxidative stress in pancreatic tissues of streptozotocin-induced diabetic rats.

    PubMed

    Prasath, Gopalan Sriram; Sundaram, Chinnakrishnan Shanmuga; Subramanian, Sorimuthu Pillai

    2013-10-01

    Persistent hyperglycemia is associated with chronic oxidative stress which contributes to the development and progression of diabetes-associated complications. The sensitivity of pancreatic β-cells to oxidative stress has been attributed to their low content of antioxidants compared with other tissues. Bioactive compounds with potent antidiabetic properties have been shown to ameliorate hyperglycemia mediated oxidative stress. Recently, we have reported that oral administration of fisetin (10 mg/Kg b.w.), a bioflavonoid found to be present in strawberries, persimmon, to STZ-induced experimental diabetic rats significantly improved normoglycemia. The present study was aimed to evaluate the antioxidant potential of fisetin in both in vitro and in vivo. Diabetes was induced by single intraperitoneal injection of streptozotocin (50 mg/kg body weight). Fisetin was administered orally for 30 days. At the end of the study, all animals were killed. Blood samples were collected for the biochemical estimations. The antioxidant status was evaluated. Histological examinations were performed on pancreatic tissues. Fisetin treatment showed a significant decline in the levels of blood glucose, glycosylated hemoglobin (HbA1c), NF-kB p65 unit (in pancreas) and IL-1β (plasma), serum nitric oxide (NO) with an elevation in plasma insulin. The treatment also improved the antioxidant status in pancreas as well as plasma of diabetic rats indicating the antioxidant potential of fisetin. In addition, the results of DPPH and ABTS assays substantiate the free radical scavenging activity of fisetin. Histological studies of the pancreas also evidenced the tissue protective nature of fisetin. It is concluded that, fisetin possesses antioxidant and anti-inflammatory property and may be considered as an adjunct for the treatment of diabetes. PMID:23277230

  16. Silver nanoparticle based surface enhanced Raman scattering spectroscopy of diabetic and normal rat pancreatic tissue under near-infrared laser excitation

    NASA Astrophysics Data System (ADS)

    Huang, H.; Shi, H.; Feng, S.; Lin, J.; Chen, W.; Huang, Z.; Li, Y.; Yu, Y.; Lin, D.; Xu, Q.; Chen, R.

    2013-04-01

    This paper presents the use of high spatial resolution silver nanoparticle based near-infrared surface enhanced Raman scattering (SERS) from rat pancreatic tissue to obtain biochrmical information about the tissue. A high quality SERS signal from a mixture of pancreatic tissues and silver nanoparticles can be obtained within 10 s using a Renishaw micro-Raman system. Prominent SERS bands of pancreatic tissue were assigned to known molecular vibrations, such as the vibrations of DNA bases, RNA bases, proteins and lipids. Different tissue structures of diabetic and normal rat pancreatic tissues have characteristic features in SERS spectra. This exploratory study demonstrated great potential for using SERS imaging to distinguish diabetic and normal pancreatic tissues on frozen sections without using dye labeling of functionalized binding sites.

  17. Identification of mediators stimulating proliferation and matrix synthesis of rat pancreatic stellate cells.

    PubMed

    Schneider, E; Schmid-Kotsas, A; Zhao, J; Weidenbach, H; Schmid, R M; Menke, A; Adler, G; Waltenberger, J; Grünert, A; Bachem, M G

    2001-08-01

    The aim of this study was to identify fibrogenic mediators stimulating activation, proliferation, and/or matrix synthesis of rat pancreatic stellate cells (PSC). PSC were isolated from the pancreas of normal Wistar rats and from rats with cerulein pancreatitis. Cell activation was demonstrated by immunofluorescence microscopy of smooth muscle alpha-actin (SMA) and real-time quantitative RT-PCR of SMA, fibronectin, and transforming growth factor (TGF)-beta(1). Proliferation was measured by bromodeoxyuridine incorporation. Matrix synthesis was demonstrated on the protein and mRNA level. Within a few days in primary culture, PSC changed their phenotype from fat-storing to SMA-positive myofibroblast-like cells expressing platelet-derived growth factor (PDGF) alpha- and PDGF beta-receptors. TGF-beta(1) and tumor necrosis factor (TNF)-alpha accelerated the change in the cells' phenotype. Addition of 50 ng/ml PDGF and 5 ng/ml basic fibroblast growth factor (bFGF) to cultured PSC significantly stimulated cell proliferation (4.37 +/- 0.49- and 2.96 +/- 0.39-fold of control). Fibronectin synthesis calculated on the basis of DNA was stimulated by 5 ng/ml bFGF (3.44 +/- 1.13-fold), 5 ng/ml TGF-beta(1) (2.46 +/- 0.89-fold), 20 ng/ml PDGF (2.27 +/- 0.68-fold), and 50 ng/ml TGF-alpha (1.87 +/- 0.19-fold). As shown by RT-PCR, PSC express predominantly the splice variant EIII-A of fibronectin. Immunofluorescence microscopy and Northern blot confirmed that in particular bFGF and TGF-beta(1) stimulated the synthesis of fibronectin and collagens type I and III. In conclusion, our data demonstrate that 1) TGF-beta(1) and TNF-alpha accelerate the change in the cell phenotype, 2) PDGF represents the most effective mitogen, and 3) bFGF, TGF-beta(1), PDGF, and, to a lesser extent, TGF-alpha stimulate extracellular matrix synthesis of cultured rat PSC. PMID:11443052

  18. Rat pancreatic stellate cells secrete matrix metalloproteinases: implications for extracellular matrix turnover

    PubMed Central

    Phillips, P A; McCarroll, J A; Park, S; Wu, M-J; Pirola, R; Korsten, M; Wilson, J S; Apte, M V

    2003-01-01

    Background: Pancreatic fibrosis is a characteristic feature of chronic pancreatic injury and is thought to result from a change in the balance between synthesis and degradation of extracellular matrix (ECM) proteins. Recent studies suggest that activated pancreatic stellate cells (PSCs) play a central role in pancreatic fibrogenesis via increased synthesis of ECM proteins. However, the role of these cells in ECM protein degradation has not been fully elucidated. Aims: To determine: (i) whether PSCs secrete matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) and, if so (ii) whether MMP and TIMP secretion by PSCs is altered in response to known PSC activating factors such as tumour necrosis factor α (TNF-α), transforming growth factor β1 (TGF-β1), interleukin 6 (IL-6), ethanol, and acetaldehyde. Methods: Cultured rat PSCs (n=3–5 separate cell preparations) were incubated at 37°C for 24 hours with serum free culture medium containing TNF-α (5–25 U/ml), TGF-β1 (0.5–1 ng/ml), IL-6 (0.001–10 ng/ml), ethanol (10–50 mM), or acetaldehyde (150–200 μM), or no additions (controls). Medium from control cells was examined for the presence of MMPs by zymography using a 10% polyacrylamide-0.1% gelatin gel. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to examine gene expression of MMP9 and the tissue inhibitors of metalloproteinases TIMP1 and TIMP2. Western blotting was used to identify a specific MMP, MMP2 (a gelatinase that digests basement membrane collagen and the dominant MMP observed on zymography) and a specific TIMP, TIMP2. Reverse zymography was used to examine functional TIMPs in PSC secretions. The effect of TNF-α, TGF-β1, and IL-6 on MMP2 secretion was assessed by densitometry of western blots. The effect of ethanol and acetaldehyde on MMP2 and TIMP2 secretion was also assessed by this method. Results: Zymography revealed that PSCs secrete a number of MMPs including proteinases with molecular

  19. Chromosomal mapping of pancreatic islet morphological features and regulatory hormones in the spontaneously diabetic (Type 2) Goto-Kakizaki rat.

    PubMed

    Finlay, Clare; Argoud, Karène; Wilder, Steven P; Ouali, Fetta; Ktorza, Alain; Kaisaki, Pamela J; Gauguier, Dominique

    2010-10-01

    Insulin resistance and altered endocrine pancreas function are central pathophysiological features of type 2 diabetes mellitus (T2DM). The Goto-Kakizaki (GK) rat is a model of spontaneous T2DM characterised by reduced beta cell mass and genetically determined glucose intolerance and altered insulin secretion. To identify genetic determinants of endocrine pancreas histopathology, we carried out quantitative trait locus (QTL) mapping of histological phenotypes (beta cell mass -BCM and insulin-positive cell area -IPCA) and plasma concentration of hormones and growth factors in a F2 cohort derived from GK and normoglycemic Brown Norway rats. Although IPCA and BCM in the duodenal region of the pancreas were highly positively correlated (P < 10(-6)), and similarly in the splenic region, both measures were poorly correlated when comparing duodenal and splenic phenotypes. Strongest evidence of linkage to pancreas morphological traits was obtained between BCM and chromosome 10 (LOD 3.2). Evidence of significant linkage (LOD 4.2) to plasma corticosterone was detected in a region of chromosome 1 distal to other QTLs previously identified in the GK. Male-specific genetic effects were detected, including linkages (LOD > 4) to growth hormome (GH) on chromosome 6 and prolactin on chromosome 17. These data suggest independent genetic control of the structure and function of ontologically different regions of the endocrine pancreas. Novel QTLs for corticosterone, prolactin and GH may contribute to diabetes in the GK. The QTLs that we have identified in this, and previous genetic studies collectively underline the complex and multiple mechanisms involved in diabetes in the GK strain. PMID:20878524

  20. Proteomic analysis of conditioned media from glucose responsive and glucose non-responsive phenotypes reveals a panel of secreted proteins associated with beta cell dysfunction.

    PubMed

    Dowling, Paul; Shields, William; Rani, Sweta; Meleady, Paula; Henry, Michael; Jeppesen, Per; O'Driscoll, Lorraine; Clynes, Martin

    2008-11-01

    Media conditioned by dysfunctioning pancreatic beta cells offer an excellent source of potential protein markers associated with this phenotype. Proteins identified from cell culture model systems are often found to be of importance clinically. Previous work by us and others have shown that low-passage MIN-6 cells (MIN-6(L)) respond to changes in glucose concentrations, producing an approximately 5.5-fold glucose-stimulated insulin secretion (GSIS) in response to 26.7 mmol/L, compared with 3.3 mmol/L, glucose. After continuous culture or high-passage (MIN-(H)), this GSIS was no longer present and thus represents an excellent model system for investigating beta cell dysfunction. Employing 2-D difference gel electrophoresis and mass spectrometry a panel of protein markers were identified in conditioned media (CM) from MIN-6(L) and MIN-6(H) beta cells. These proteins, including secretogranin II, secretogranin III and transthyretin, are associated with secretory granule biogenesis and were found to have substantially increased levels in the CM from the non-responsive high-passage MIN-6 beta cells. A panel of protein markers found to have increased abundance levels in CM from MIN-6(H) compared with MIN-6(L) beta cells may have the potential to be used clinically for assessing beta cell function and to monitor the effects of specific therapeutics. PMID:18924105

  1. Mechanisms of beta-cell death in type 2 diabetes.

    PubMed

    Donath, Marc Y; Ehses, Jan A; Maedler, Kathrin; Schumann, Desiree M; Ellingsgaard, Helga; Eppler, Elisabeth; Reinecke, Manfred

    2005-12-01

    A decrease in the number of functional insulin-producing beta-cells contributes to the pathophysiology of type 2 diabetes. Opinions diverge regarding the relative contribution of a decrease in beta-cell mass versus an intrinsic defect in the secretory machinery. Here we review the evidence that glucose, dyslipidemia, cytokines, leptin, autoimmunity, and some sulfonylureas may contribute to the maladaptation of beta-cells. With respect to these causal factors, we focus on Fas, the ATP-sensitive K+ channel, insulin receptor substrate 2, oxidative stress, nuclear factor-kappaB, endoplasmic reticulum stress, and mitochondrial dysfunction as their respective mechanisms of action. Interestingly, most of these factors are involved in inflammatory processes in addition to playing a role in both the regulation of beta-cell secretory function and cell turnover. Thus, the mechanisms regulating beta-cell proliferation, apoptosis, and function are inseparable processes. PMID:16306327

  2. Antioxidant and Anti-Inflammatory Effects of Coenzyme Q10 on L-Arginine-Induced Acute Pancreatitis in Rat

    PubMed Central

    Mirmalek, Seyed Abbas; Gholamrezaei Boushehrinejad, Ala; Yavari, Hassan; Kardeh, Bahareh; Parsa, Yekta; Salimi-Tabatabaee, Seyed Alireza; Yadollah-Damavandi, Soheila; Parsa, Tina; Shahverdi, Ehsan

    2016-01-01

    This study was aimed at evaluating the protective effect of coenzyme Q10 on L-arginine-induced acute pancreatitis in rats regarding biomarkers and morphologic changes. Thirty-two male Sprague-Dawley rats were divided into 4 equal groups. Control group received intraperitoneal normal saline, while in sham and experimental groups 1 and 2 pancreatitis was induced with L-arginine. E1 and E2 groups were treated with a single dose of 100 and 200 mg/kg Q10, respectively. Serum lipase and amylase, along with pancreas IL-10, IL-1β, and TNF-α, were measured. For evaluation of oxidative stress, pancreatic superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), and myeloperoxidase (MPO) were assessed. Histopathological examination for morphologic investigation was conducted. Serum amylase and lipase, as well as TNF-α and IL-1β cytokines, reverted with administration of Q10 in consistence with dosage. In contrast, Q10 assisted in boosting of IL-10 with higher dosage (200 mg/kg). A similar pattern for oxidative stress markers was noticed. Both MDA and MPO levels declined with increased dosage, contrary to elevation of SOD and GSH. Histopathology was in favor of protective effects of Q10. Our findings proved the amelioration of pancreatic injury by Q10, which suggest the anti-inflammatory and antioxidant property of Q10 and its potential therapeutic role. PMID:27190575

  3. Amelioration of pancreatic and renal derangements in streptozotocin-induced diabetic rats by polyphenol extracts of Ginger (Zingiber officinale) rhizome.

    PubMed

    Kazeem, Mutiu Idowu; Akanji, Musbau Adewunmi; Yakubu, Musa Toyin

    2015-12-01

    Free and bound polyphenol extracts of Zingiber officinale rhizome were investigated for their antidiabetic potential in the pancreatic and renal tissues of diabetic rats at a dose of 500mg/kg body weight. Forty Wistar rats were completely randomized into five groups: A-E consisting of eight animals each. Group A (control) comprises normal healthy animals and were orally administered 1.0mL distilled water on a daily basis for 42 days while group B-E were made up of 50mg/kg streptozotocin (STZ)-induced diabetic rats. Group C and D received 1.0mL 500mg/kg body weight free and bound polyphenol extracts respectively while group E received 1.0mL 0.6mg/kg of glibenclamide. Administration of the extracts to the diabetic rats significantly reduced (p<0.05) serum glucose and urea concentrations, increased (p<0.05) serum insulin and Homeostatic Model Assessment for β-cell dysfunction (HOMA-β) while the level of creatinine and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) were not affected. Histological examination of the pancreas and kidney revealed restoration of the structural derangements caused by streptozotocin in the polyphenol extracts treated diabetic rats compared to the control groups. Therefore, polyphenols from Zingiber officinale could ameliorate diabetes-induced pancreatic and renal derangements in rats. PMID:26349770

  4. Normal pancreatic and intestinal enzymes in hypophagic growth-retarded rats that received dorsomedial hypothalamic lesions shortly after weaning.

    PubMed

    Bernardis, L L; Lee, P C; Brooks, S; Lebenthal, E

    1984-08-01

    Male weanling Sprague-Dawley rats received bilateral electrolytic lesions in the dorsomedial hypothalamic nuclei (DMNL rats). Sham-operated rats served as controls. After being fed lab chow for two postoperative weeks, the animals were divided into four groups. One group of DMNL rats and controls received a high-caloric diet (high-fat diet, chocolate chip cookies, 32% sucrose solution, potato chips and marshmallows), whereas another group of DMNL rats and controls continued to receive lab chow. The experiment was terminated on the 185th postoperative day. In accordance with previous findings, DMNL rats, irrespective of diet, were lighter and shorter than controls. In addition, DMNL rats fed junk food were lighter than DMNL rats fed lab chow, and junk-fed controls weighed as much as chow-fed controls. Both DMNL rats and controls fed junk food were also shorter and showed higher carcass fat than their chow-fed counterparts. Also, DMNL rats fed junk food had less carcass fat than junk-fed sham-operated controls, whereas in accordance with previous findings, there was no difference between chow-fed DMNL rats and chow-fed sham-operated controls. Irrespective of diet, DMNL rats ate less calories than their respective sham-operated controls. Both absolute and percent pancreas weight and protein/pancreas were unaffected in DMNL rats but were reduced in both junk-fed groups in comparison with their chow-fed counterparts. Both concentrations and contents of pancreatic trypsinogen, amylase and lipase were unaffected in DMNL rats but total activities of all three enzymes were dramatically reduced in the junk-fed compared with the chow-fed DMNL rats.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6483936

  5. Correlation Between Pancreatic Islet Uncoupling Protein-2 (UCP2) mRNA Concentration And Insulin Status in Rats

    PubMed Central

    Kassis, Nadim; Bernard, Catherine; Pusterla, Aristide; Casteilla, Louis; Pétnicaud, Luc; Richard, Denis; Ricquier, Daniel

    2000-01-01

    Hypothesizing that UCP2 may influence insulin secretion by modifying the ATP/ADP ratio within pancreatic islets, we have investigated the expression of intraislet UCP2 gene in rats showing insulin oversecretion (non-diabetic Zucker fa/fa obese rats, glucose-infused Wistar rats) or insulin undersecretion (fasting and mildly diabetic rats). We found that in Zucker fa/fa obese rats, hyperinsulinemia (1222 ± 98 pmol/1 vs. 128 ± 22 pmol/1 in lean Zucker rats) was accompanied by a significant increase in UCP2 mRNA levels. In rat submitted to a 5 day infusion with glucose, hyperinsulinemia (1126 ± 101 pmol/l vs. 215 ± 25 pmol/1 in Wistar control rats), coincided with an enhanced intraislet UCP2 gene expression, whereas a 8h or a 2 day-infusion did not induce significant changes in UCP2 mRNA expression. In rats made hypoinsulinemic and mildly diabetic by the injection of a low dose of streptozotocin, and in 4-day-fasting rats (plasma insulin 28 ± 5 pmol/1) UCP2 gene expression was sharply decreased. A 3-day-fast was ineffective. The data show the existence of a time-dependent correlation between islet mRNA UCP2 and insulin that may be interpreted as an adaptative response to prolonged insulin excess. PMID:11467409

  6. Optogenetic Control of Pancreatic Islets.

    PubMed

    Reinbothe, Thomas M; Mollet, Inês G

    2016-01-01

    In light of the emerging diabetes epidemic, new experimental approaches in islet research are needed to elucidate the mechanisms behind pancreatic islet dysfunction and to facilitate the development of more effective therapies. Optogenetics has created numerous new experimental tools enabling us to gain insights into processes little was known about before. The spatial and temporal precision that it can achieve is also attractive for studying the cells of the pancreatic islet and we set out to explore the possibilities of this technology for our purposes. We here describe how to use the islets of an "optogenetic beta-cell" mouse line in islet batch incubations and Ca(2+) imaging experiments. This protocol enables light-induced insulin release and provides an all-optical solution to control and measure intracellular Ca(2+) levels in pancreatic beta-cells. The technique is easy to set up and provides a useful tool for controlling the activity of distinct islet cell populations. PMID:26965119

  7. Characteristics of pancreatic cholesterol esterase binding to and uptake by rat intestinal cells

    SciTech Connect

    Wright Wiesenfeld, P.L.

    1988-01-01

    In the intestinal lumen cholesterol esterase derived from pancreatic juice catalyzes the hydrolysis of cholesteryl esters (CE). The characteristics of Ce'ase binding to and uptake by rat intestinal cells were determined. CE'ase purified from rat pancreas with a specific activity 2 fold higher and a yield 5 fold greater than that previously attainable was judged as homogeneous on the basis of SDS-PAGE and sedimentation equilibrium centrifugation. Intestinal cell types and membranes were isolated and judged as pure on the basis of marker enzyme analyses. The enzyme was radiolabeled with ({sup 125}-I) to a specific radioactivity of 55 Ci/mmole with retention of biological activity, gross molecular size, secondary structure, and immunological properties. ({sup 125}-I) CE'ase bound preferentially to mature absorptive cells from proximal intestine and their brush border membranes. A specific, low affinity binding phenomenon was demonstrated with the following characteristics: linearity with increasing ligand concentration (non-saturability) or cell concentration, time and temperature dependency, and irreversibility. Native CE'ase, at a 500 fold molar excess did not displace bound ({sup 125}-I) CE'ase.

  8. Antihyperglycemic activity of kinsenoside, a high yielding constituent from Anoectochilus roxburghii in streptozotocin diabetic rats.

    PubMed

    Zhang, Yonghui; Cai, Jinyan; Ruan, Hanli; Pi, Huifang; Wu, Jizhou

    2007-11-01

    Different doses of kinsenoside, a high yielding constituent from Anoectochilus roxburghii, was orally administered to further investigate its biological activity and pharmacological mechanisms that involve in the hypoglycemic effect on streptozotocin (STZ) diabetic rats. Our study showed that this compound exhibited significantly antihyperglycemic activity at the dose of 15mg/kg body weight, which is speculated to be partially attributed to modulating the activity of enzymatic antioxidants, scavenging free radicals, and reducing the content of factor NO. Much more intact beta cells in the islets of Langerhans with denser insulin in kinsenoside-treated groups than the negative control were observed, which greatly supported the morphological and functional elucidation. These results displayed that kinsenoside could be useful for repairing beta cells in pancreatic islet injury as well as improving its function. The OGTT evidenced that this compound could promote the glucose tolerance of acute glucose increase in both diabetic and normal healthy rats. PMID:17869039

  9. Calbindin-D(28k) controls [Ca(2+)](i) and insulin release. Evidence obtained from calbindin-d(28k) knockout mice and beta cell lines

    NASA Technical Reports Server (NTRS)

    Sooy, K.; Schermerhorn, T.; Noda, M.; Surana, M.; Rhoten, W. B.; Meyer, M.; Fleischer, N.; Sharp, G. W.; Christakos, S.

    1999-01-01

    The role of the calcium-binding protein, calbindin-D(28k) in potassium/depolarization-stimulated increases in the cytosolic free Ca(2+) concentration ([Ca(2+)](i)) and insulin release was investigated in pancreatic islets from calbindin-D(28k) nullmutant mice (knockouts; KO) or wild type mice and beta cell lines stably transfected and overexpressing calbindin. Using single islets from KO mice and stimulation with 45 mM KCl, the peak of [Ca(2+)](i) was 3.5-fold greater in islets from KO mice compared with wild type islets (p < 0.01) and [Ca(2+)](i) remained higher during the plateau phase. In addition to the increase in [Ca(2+)](i) in response to KCl there was also a significant increase in insulin release in islets isolated from KO mice. Evidence for modulation by calbindin of [Ca(2+)](i) and insulin release was also noted using beta cell lines. Rat calbindin was stably expressed in betaTC-3 and betaHC-13 cells. In response to depolarizing concentrations of K(+), insulin release was decreased by 45-47% in calbindin expressing betaTC cells and was decreased by 70-80% in calbindin expressing betaHC cells compared with insulin release from vector transfected betaTC or betaHC cells (p < 0.01). In addition, the K(+)-stimulated intracellular calcium peak was markedly inhibited in calbindin expressing betaHC cells compared with vector transfected cells (225 nM versus 1,100 nM, respectively). Buffering of the depolarization-induced rise in [Ca(2+)](i) was also observed in calbindin expressing betaTC cells. In summary, our findings, using both isolated islets from calbindin-D(28k) KO mice and beta cell lines, establish a role for calbindin in the modulation of depolarization-stimulated insulin release and suggest that calbindin can control the rate of insulin release via regulation of [Ca(2+)](i).

  10. Induced ICER I{gamma} down-regulates cyclin A expression and cell proliferation in insulin-producing {beta} cells

    SciTech Connect

    Inada, Akari; Weir, Gordon C.; Bonner-Weir, Susan . E-mail: susan.bonner-weir@joslin.harvard.edu

    2005-04-15

    We have previously found that cyclin A expression is markedly reduced in pancreatic {beta}-cells by cell-specific overexpression of repressor inducible cyclic AMP early repressor (ICER I{gamma}) in transgenic mice. Here we further examined regulatory effects of ICER I{gamma} on cyclin A gene expression using Min6 cells, an insulin-producing cell line. The cyclin A promoter luciferase assay showed that ICER I{gamma} directly repressed cyclin A gene transcription. In addition, upon ICER I{gamma} overexpression, cyclin A mRNA levels markedly decreased, thereby confirming an inhibitory effect of ICER I{gamma} on cyclin A expression. Suppression of cyclin A results in inhibition of BrdU incorporation. Under normal culture conditions endogenous cyclin A is abundant in these cells, whereas ICER is hardly detectable. However, serum starvation of Min6 cells induces ICER I{gamma} expression with a concomitant very low expression level of cyclin A. Cyclin A protein is not expressed unless the cells are in active DNA replication. These results indicate a potentially important anti-proliferative effect of ICER I{gamma} in pancreatic {beta} cells. Since ICER I{gamma} is greatly increased in diabetes as well as in FFA- or high glucose-treated islets, this effect may in part exacerbate diabetes by limiting {beta}-cell proliferation.

  11. Furosemide reduces insulin release by inhibition of Cl sup minus and Ca sup 2+ fluxes in. beta. -cells

    SciTech Connect

    Sandstroem, P.E.; Sehlin, J. )

    1988-11-01

    The effect of furosemide on insulin release, glucose oxidation, {sup 36}Cl{sup {minus}} fluxes, and {sup 45}Ca{sup 2+} uptake was studied in isolated, {beta}-cell-rich pancreatic islets from ob/ob mice. Low concentrations of furosemide (0.01-0.1 mM) reduced the glucose-induced insulin release, whereas high doses (1-10 mM) increased basal and glucose-induced release. Furosemide at concentrations that reduced glucose-induced insulin release did not affect the islet production of {sup 14}CO{sub 2} from D-(U-{sup 14}C)glucose. The influx rate and equilibrium content of {sup 36}Cl{sup {minus}} were reduced by furosemide, whereas the basal and glucose-stimulated {sup 36}Cl{sup {minus}} efflux rates were unaffected. The glucose-induced uptake of {sup 45}Ca{sup 2+} was inhibited by furosemide. It is suggested that the diabetogenic action of furosemide may be due, at least in part, to direct inhibition of insulin release from the pancreatic {beta}-cells. This may be caused primarily by inhibition of an inwardly directed Cl{sup {minus}} pump, leading to a reduced transmembrane electrochemical gradient for chloride in the {beta}-cells. This reduced gradient in combination with unaltered Cl{sup {minus}} permeability may lead to decreased total outward Cl{sup {minus}} transport, a factor associated with stimulated calcium uptake and insulin release.

  12. Efficacy of thymosin α1 and interferon α for the treatment of severe acute pancreatitis in a rat model

    PubMed Central

    WANG, XIAOQIN; ZENG, XIAOYAN; YANG, BO; ZHAO, SHAN; CHEN, WEI; GUO, XUAN

    2015-01-01

    The present study aimed to investigate the effects of treatment with thymosin α1 (TA1) or interferon α (IFNα) following the establishment of severe acute pancreatitis (SAP) in rats. A total of 144 Sprague-Dawley rats were randomly divided into four groups. The rats in all four groups were celiotomized, and the rats in the control group were administered with an intravenous injection of saline. The three other groups were administered with 5% 1 ml/kg sodium taurocholate via the cholangiopancreatic duct. SAP group rats were administered with an intravenous injection of saline; TA1 group rats received 26.7 µg/kg TA1; and interferon α (INFα) group rats received 4.0×105 U/kg IFNα. The rats were anesthetized and blood samples were collected from the animals 3, 12 and 24 h after surgery. The levels of T cell subsets, serum enzyme indicators, cytokines and procalcitonin (PCT) were measured. The general conditions of the rats were observed until sacrifice, and pancreatic and lung tissue samples were sampled for hematoxylin and eosin staining and histological scoring. The expression levels of aspartate transaminase, lactate dehydrogenase, α-amylase (AMY), P-type-amylase, lipase, PCT, tumor-necrosis factor α, interleukin (IL)-4, IL-5, and IL-18 in the TA1 and IFNα-treated rats were significantly lower, compared with those of the SAP rats within the first 24 h of model establishment (P<0.05). The TA1 and IFNα-treated rats exhibited significantly increased levels of CD3+, CD4+ and CD8+ T cells, and an increased ratio of CD4+/CD8+ cells, compared with SAP rats. Histological analysis revealed that the TA1 and IFNα-treated rats exhibited significantly ameliorated pancreas and lung damage, and mortality rates were reduced from 50.0% (6/12) to 25.0% (3/12) and 33.3% (4/12), respectively. The immunomodulatory agents TA1 and IFNα reduced acute inflammation, decreasing cell damage and enhancing immune function and survival rates in the SAP rats. PMID:26330363

  13. Sources of beta cells inside the pancreas.

    PubMed

    De Groef, Sofie; Staels, Willem; Van Gassen, Naomi; Lemper, Marie; Yuchi, Yixing; Sojoodi, Mozhdeh; Bussche, Leen; Heremans, Yves; Leuckx, Gunter; De Leu, Nico; Van de Casteele, Mark; Baeyens, Luc; Heimberg, Harry

    2016-09-01

    The generation of beta(-like) cells to compensate for their absolute or relative shortage in type 1 and type 2 diabetes is an obvious therapeutic strategy. Patients first received grafts of donor islet cells over 25 years ago, but this procedure has not become routine in clinical practice because of a donor cell shortage and (auto)immune problems. Transplantation of differentiated embryonic and induced pluripotent stem cells may overcome some but not all the current limitations. Reprogramming exocrine cells towards functional beta(-like) cells would offer an alternative abundant and autologous source of beta(-like) cells. This review focuses on work by our research group towards achieving such a source of cells. It summarises a presentation given at the 'Can we make a better beta cell?' symposium at the 2015 annual meeting of the EASD. It is accompanied by two other reviews on topics from this symposium (by Amin Ardestani and Kathrin Maedler, DOI: 10.1007/s00125-016-3892-9 , and by Heiko Lickert and colleagues, DOI: 10.1007/s00125-016-3949-9 ) and a commentary by the Session Chair, Shanta Persaud (DOI: 10.1007/s00125-016-3870-2 ). PMID:27053238

  14. Sulfasalazine inhibits inflammation and fibrogenesis in pancreas via NF-κB signaling pathway in rats with oxidative stress-induced pancreatic injury

    PubMed Central

    Wang, Ya-Ru; Tian, Fei-Long; Yan, Ming-Xian; Fan, Jin-Hua; Wang, Li-Yun; Kuang, Rong-Guang; Li, Yan-Qing

    2016-01-01

    Background Pathogenesis and effective therapeutics of chronic pancreatic inflammation and fibrosis remain uncertain. Purpose To investigate the effects of sulfasalazine (SF) on pancreatic inflammation and fibrogenesis. Methods Chronic pancreatic injury in rats was induced by diethyldithiocarbamate (DDC) and interfered by SF through intraperitoneal injection. The rats were divided into five groups: group N, normal control group, rats were treated with dilated water only; group DS1, rats received SF (10 mg/kg) 2 hours before DDC treatment; group DS2, rats were treated with DDC and then SF (100 mg/kg, twice a week); group DS3, rats were treated with DDC, then SF (100 mg/kg, thrice a week); and group DDC, rats were treated with DDC only. Pancreatic inflammation and fibrosis were determined by hematoxylin and eosin staining and Sirius red staining. The genes and proteins related to NF-κB pathway and fibrogenesis including NF-κB/p65, TNF-α, ICAM-1, α-SMA, and Con 1 were detected by immunohistochemical staining, reverse transcription polymerase chain reaction, and Western blotting. Results Rats in the DDC and DS1 groups showed the highest histological scores after DDC treatment, but the scores of DS2 and DS3 groups decreased significantly when compared with the DDC group. Sirius red staining showed collagen formation clearly in DDC and DS1 rats rather than in DS2 and DS3 rats. NF-κB/p65, ICAM-1, and α-SMA were strongly expressed in DDC and DS1 rats, while DS2 and DS3 rats showed mild to moderate expression by immunohistochemistry. Reverse transcription polymerase chain reaction showed increased levels of NF-κB/p65, ICAM-1, TNF-α, α-SMA, and Con 1 mRNA in DDC and DS1 rats in comparison to normal controls. The mRNA levels of these molecules in DS2 and DS3 rats were significantly lower than those in DS1 and DDC rats. Western blotting demonstrated that the NF-κB/p65, ICAM-1, and α-SMA expressions in pancreatic tissues of the rats of the DDC group were more clear

  15. Salutary and prophylactic effect of pentadecapeptide BPC 157 on acute pancreatitis and concomitant gastroduodenal lesions in rats.

    PubMed

    Sikirić, P; Seiwerth, S; Grabarević, Z; Rucman, R; Petek, M; Jagić, V; Turković, B; Rotkvić, I; Mise, S; Zoricić, I; Jurina, L; Konjevoda, P; Hanzevacki, M; Ljubanović, D; Separović, J; Gjurasin, M; Bratulić, M; Artuković, B; Jelovac, N; Buljat, G

    1996-07-01

    The superior effectiveness of a new pentadecapeptide, BPC 157, on gastrointestinal and liver lesions, in conjunction with an antiinflammatory and analgetic activity was recently noted. In the present study, BPC 157 was tested as either a protective or healing agent in bile duct ligation-induced acute pancreatitis in rats. In addition, the positive influence of BPC 157 on concomitantly developed gastric and duodenal lesions was simultaneously investigated. BPC 157 (10 microg, 10 ng/kg body wt, intraperitoneally or intragastrically) was given prophylactically 1 hr before ligation, whereas the therapy was given once daily beginning with the 24 hr following ligation (last application 24 hr before killing). The effect was investigated at daily intervals until the end of the fifth day after ligation. In the pretreatment regimen, a strong pancreas protection was obtained. When applied in the condition of already established severe acute pancreatitis, an obvious salutory effect was consistently noted. Assessing the appearance of the necrosis, edema, neutrophils, and mononuclears, consistently less necrosis, edema, and neutrophils, but more mononuclears, were found in BPC-treated rats. Likewise, in studies of the serum amylase values, relative to control data, a markedly lower rise (BPC pretreatment regimen) as well as a worsening of the already raised values (BPC therapy regimen) was noted. Along with its beneficial effect on pancreatitis, a positive influence of BPC 157 on the gastric and duodenal lesion course in bile duct-ligated rats was noted in both the pre- and posttreatment regimen. Taken together, in further studies of acute pancreatitis therapy, BPC could be an interesting and useful agent with an additional positive impact on concomitant gastroduodenal pathology. PMID:8689934

  16. Antidiabetic effects of Eucalyptus globulus on pancreatic islets: a stereological study.

    PubMed

    Mahmoudzadeh-Sagheb, H; Heidari, Z; Bokaeian, M; Moudi, B

    2010-05-01

    The leaves of Eucalyptus globulus (eucalyptus) are used for the treatment of diabetes mellitus in traditional medicine. The aim of this study was to evaluate the effects of eucalyptus on streptozotocin (STZ)-induced damage in pancreatic islands by stereological methods. Fifty mature normoglycaemic male Wistar rats, weighing 200-250 g, were selected and randomly divided into 5 groups (n = 10): control; STZ-induced diabetic (D) - by intraperitoneal injection of 60 mg/kg streptozotocin; treated control (TC); and treated diabetic (TD1, 2), respectively, received 20 and 62.5 g/kg of eucalyptus in their diet, and 2.5 g/L aqueous extract of eucalyptus in their drinking water from one week after induction of diabetes. After four weeks of the experiment, stereological estimation of volume density and total volume of islets and beta cells, volume-weighted mean islet volume, mass of the islets and pancreas, and total number of islets were carried out. Administration of eucalyptus significantly decreased the weight loss and increase of water and food intake in the treated diabetic groups in comparison to the STZ-induced diabetic (D) group. Volume density and total volume of islets, volume-weighted mean islet volume, mass of islets, and mass of pancreas of both treated diabetic groups were higher than the D group. In TD2, these stereological parameters increased significantly compared to the D group (p < 0.001). Volume density and total volume of beta cells increased 21% and 65%, respectively, in the TD2 group, but it was not statistically significant compared to the diabetic group (p > 0.05). The results suggested that Eucalyptus globulus with a dose-dependent manner ameliorates diabetic states by partial restoration of pancreatic beta cells and repair of STZ-induced damage in rats. This study suggests a beneficial effect of eucalyptus in the treatment of diabetes. PMID:20512762

  17. Serotonin competence of mouse beta cells during pregnancy.

    PubMed

    Goyvaerts, Lotte; Schraenen, Anica; Schuit, Frans

    2016-07-01

    Pregnancy is a key mammalian reproductive event in which growth and differentiation of the fetus imposes extra metabolic and hormonal demands on the mother. Its successful outcome depends on major changes in maternal blood circulation, metabolism and endocrine function. One example is the endocrine pancreas, where beta cells undergo a number of changes in pregnancy that result in enhanced functional beta cell mass in order to compensate for the rising metabolic needs for maternal insulin. During the last 5 years, a series of studies have increased our understanding of the molecular events involved in this functional adaptation. In the mouse, a prominent functional change during pregnancy is the capacity of some beta cells to produce serotonin. In this review we will discuss the mechanism and potential effects of pregnancy-related serotonin production in beta cells, considering functional consequences at the local intra-islet and systemic level. PMID:27056372

  18. Selective destruction of mouse islet beta cells by human T lymphocytes in a newly-established humanized type 1 diabetic model

    SciTech Connect

    Zhao, Yong; Guo, Chengshan; Hwang, David; Lin, Brian; Dingeldein, Michael; Mihailescu, Dan; Sam, Susan; Sidhwani, Seema; Zhang, Yongkang; Jain, Sumit; Skidgel, Randal A.; Prabhakar, Bellur S.; Mazzone, Theodore; Holterman, Mark J.

    2010-09-03

    Research highlights: {yields} Establish a human immune-mediated type 1 diabetic model in NOD-scid IL2r{gamma}{sup null} mice. {yields} Using the irradiated diabetic NOD mouse spleen mononuclear cells as trigger. {yields} The islet {beta} cells were selectively destroyed by infiltrated human T cells. {yields} The model can facilitate translational research to find a cure for type 1 diabetes. -- Abstract: Type 1 diabetes (T1D) is caused by a T cell-mediated autoimmune response that leads to the loss of insulin-producing {beta} cells. The optimal preclinical testing of promising therapies would be aided by a humanized immune-mediated T1D model. We develop this model in NOD-scid IL2r{gamma}{sup null} mice. The selective destruction of pancreatic islet {beta} cells was mediated by human T lymphocytes after an initial trigger was supplied by the injection of irradiated spleen mononuclear cells (SMC) from diabetic nonobese diabetic (NOD) mice. This resulted in severe insulitis, a marked loss of total {beta}-cell mass, and other related phenotypes of T1D. The migration of human T cells to pancreatic islets was controlled by the {beta} cell-produced highly conserved chemokine stromal cell-derived factor 1 (SDF-1) and its receptor C-X-C chemokine receptor (CXCR) 4, as demonstrated by in vivo blocking experiments using antibody to CXCR4. The specificity of humanized T cell-mediated immune responses against islet {beta} cells was generated by the local inflammatory microenvironment in pancreatic islets including human CD4{sup +} T cell infiltration and clonal expansion, and the mouse islet {beta}-cell-derived CD1d-mediated human iNKT activation. The selective destruction of mouse islet {beta} cells by a human T cell-mediated immune response in this humanized T1D model can mimic those observed in T1D patients. This model can provide a valuable tool for translational research into T1D.

  19. Ventromedial hypothalamic lesions change the expression of cell proliferation-related genes and morphology-related genes in rat pancreatic islets

    PubMed Central

    Kiba, Takayoshi; Ishigaki, Yasuhito

    2014-01-01

    Studies in normal rats and ob/ob mice indicated that islet neogenesis does not occur in the intact rodent pancreas. We previously reported that ventromedial hypothalamic (VMH) lesions stimulated cell proliferation of rat pancreatic islet B and acinar cells primarily through a cholinergic receptor mechanism and examined how gene families involved in cell proliferation in total pancreatic tissue are regulated after VMH lesions formation. This study examined how gene families involved in cell proliferation in pancreatic islets alone are regulated after VMH lesions formation. Pancreatic islet RNA was extracted, and differences in gene expression profiles between rats at day 3 after VMH lesioning and sham-VMH-lesioned rats were investigated using DNA microarray and real-time polymerase chain reaction. VMH lesions regulated genes that were involved in functions related to cell cycle and differentiation, growth, binding, apoptosis and morphology in pancreas islets. Real-time polymerase chain reaction also confirmed that gene expression of polo-like kinase 1 (Plk1) and topoisomerase (DNA) II α 170 kDa (Top2a), and stanniocalcin 1 (Stc1) were upregulated at day 3 after the VMH lesions. Ventromedial hypothalamic lesions may change the expression of cell proliferation-related genes and morphology-related genes in rat pancreatic islets. PMID:25658146

  20. Adenoviral infection or deferoxamine? Two approaches to overexpress VEGF in beta-cell lines.

    PubMed

    Langlois, Allan; Bietiger, William; Sencier, Marie-Christine; Maillard, Elisa; Pinget, Michel; Kessler, Laurence; Sigrist, Severine

    2009-07-01

    Rapid and adequate revascularization of transplanted islets is important for their survival and function during transplantation. Vascular endothelial growth factor (VEGF) could play a critical role with respect to islet revascularization. The aim of this study was to compare two strategies that are used to overexpress VEGF in beta-cells: (1) gene therapy through adenoviral infection and (2) a pharmacological approach using deferoxamine (DFO). beta-Cell lines from rat insulinoma (RINm5F) were either infected using an adenovirus encoding the gene of human VEGF 165 or incubated with DFO. One day after treatment, the viability of RINm5F cells was preserved with 10 micromol/L of DFO (103.95 +/- 5.66% toward control; n = 4). In addition, adenoviral infection maintained the viability of cells for all the concentrations used. In both treatments, overexpression of VEGF was in a comparable level. Finally, the ratio of Bax/Bcl-2 indicated that the apoptosis increased in infected beta-cells whereas treatment with DFO seems to be antiapoptotic. Our results suggest that the use of DFO could be a realistic approach to improve the vascularization of islets during transplantation. PMID:19527112

  1. Sodium Butyrate Ameliorates L-Arginine-Induced Pancreatitis and Associated Fibrosis in Wistar Rat: Role of Inflammation and Nitrosative Stress.

    PubMed

    Kanika, Gayathri; Khan, Sabbir; Jena, Gopabandhu

    2015-08-01

    Several reports indicated that histone deacetylases (HDACs) play a crucial role in inflammation and fibrogenesis. Sodium butyrate (SB) is a short-chain fatty acid having HDAC inhibition potential. The present study aimed to evaluate the protective effect of SB against L-arginine (L-Arg)-induced pancreatic fibrosis in Wistar rats. Pancreatic fibrosis was induced by twice intraperitoneal (i.p.) injections of 20% L-Arg (250 mg/100 g) at 2-h interval on day 1, 4, 7, and 10, whereas SB (800 mg/kg/day) was administrated for 10 days. At the end of the study, biochemical estimations, histological alterations, DNA damage, and the expression of various proteins were evaluated. Posttreatment of SB decreased L-Arg-induced oxidative and nitrosative stress, DNA damage, histological alterations, and fibrosis. Interestingly, posttreatment of SB significantly decreased the expression of α-smooth muscle actin, interleukin-1β, inducible nitric oxide synthase, and 3-nitrotyrosine. The present study demonstrated that posttreatment of SB alleviates L-Arg-induced pancreatic damage and fibrosis in rat. PMID:25774002

  2. Temperature dependence of high-affinity CCK receptor binding and CCK internalization in rat pancreatic acini

    SciTech Connect

    Williams, J.A.; Bailey, A.C.; Roach, E. Univ. of California, San Francisco )

    1988-04-01

    {sup 125}I-labeled cholecystokinin (CCK) binding and internalization were studied as a function of temperatures in isolated rat pancreatic acini. At 37{degree}C, acini readily bound and degraded {sup 125}I-CCK. When labeled hormone binding was inhibited by increasing amounts of unlabeled CCK, competition-inhibition curves were biphasic, consistent with both high- (K{sub d}, 18 pM) and low-affinity (K{sub d}, 13 nM) binding sites. At 4{degree}C, acini bound only one-third as much {sup 125}I-CCK and degradation was essentially abolished. At 4{degree}C, CCK competition curves were consistent with a single class of low-affinity binding sites (K{sub d}, 19 nM). Internalization of {sup 125}I-CCK was evaluated by three washing procedures utilizing acid, base, and trypsin. All were shown to remove membrane-bound {sup 125}I-CCK, and this finding was validated for trypsin by electron microscope autotradiography. When internalization of {sup 125}I-CCK was evaluated as a function of the medium concentration of CCK, both high- and low-affinity components were observed. These results suggest that high-affinity CCK binding and CCK internalization are separate temperature-sensitive processes. Moreover, internalization is not uniquely associated with high-affinity binding.

  3. Insulinotropic action of Citrullus colocynthis seed extracts in rat pancreatic islets.

    PubMed

    Benariba, Nabila; Djaziri, Rabeh; Hupkens, Emeline; Louchami, Karim; Malaisse, Willy J; Sener, Abdullah

    2013-01-01

    The present study aimed to investigate the direct in vitro effects of several distinct Citrullus colocynthis seed extracts on glucose-stimulated insulin release from pancreatic islets isolated from rats. Six extracts were tested, a crude aqueous, defatted aqueous, ethyl acetate, H2O-methanol and n-butanol extract and an extract containing a major component (fraction A) identified by gel chromatography in the ethyl acetate, n-butanol and H2O-methanol extracts. Under selected experimental conditions, the majority of extracts exhibited a positive insulinotropic action, at least when tested in the presence of 8.3 mM D-glucose. The concentration-response correlation observed with distinct extracts revealed the participation of distinct chemical compounds, including compounds with an inhibitory insulinotropic potential, in the modulation of the insulin secretory response to D-glucose. The results of the present study are relevant for further investigations which aim to identify compounds exhibiting positive insulinotropic actions. These agents may be suitable for the treatment of human diabetic subjects. PMID:23128986

  4. A model system for the study of stimulus - enzyme secretion coupling in rat pancreatic acinar cells.

    PubMed

    Guderley, H; Heisler, S

    1980-08-01

    A superfusion technique was developed as a model system for the study of stimulus-secretion coupling in collagenase-dispersed rat pancreatic acinar cells. Cells (10(7)) were combined with a slurry of Biogel P-4 beads and the mixture was decanted into a plastic column (1.5 cm X 8.5 cm) and perfused with Krebs-Ringer. Amylase activity was determined in sequentially collected effusate fractions and used to estimate the secretory rate. Carbachol, carbachol plus dibutyryl cyclic AMP, cholecystokinin-pancreozymin, and the ionophore A-23187 all stimulated a rapid increase in the rate of secretion. Cell integrity was unaffected by these stimulants as evidenced microscopically and by the lack of lactate dehydrogenase activity in the effusates. Enzymes secreted in response to secretagogues were collected, concentrated, and isoelectrofocused on polyacrylamide gels. A film detection technique was developed to localize amylase activity. The model system has the following advantages: (1) secreted proteolytic products are removed from the vicinity of cells, thereby preventing direct cellular damage and hydrolysis of peptide agonist; (2) the need to add trypsin inhibitors is eliminated and only a minimal addition of albumin (0.001%) is required, thus allowing the separation and distortion-free analysis of secreted proteins; (3) the perfusion conditions can be changed rapidly without disturbing the cells. The model described is therefore well suited to the study of both molecular and kinetic events involved in the enzyme secretory phenomenon in exocrine pancreas. PMID:6164455

  5. Betaine (trimethylglycine) as a nutritional agent prevents oxidative stress after chronic ethanol consumption in pancreatic tissue of rats.

    PubMed

    Kanbak, Gungör; Dokumacioglu, Ali; Tektas, Aysegul; Kartkaya, Kazim; Erden Inal, Mine

    2009-03-01

    In this study, we investigated the free radical-mediated cytotoxic effects of chronic ethanol consumption on the pancreatic tissue and a possible cytoprotective effect of betaine as a methyl donor and an important participant in the methionine cycle. Twenty-four male Wistar rats were divided into control, ethanol, and ethanol+betaine groups. Prior to sacrifice, all groups were fed 60 mL/diet per day for two months. Rats in the ethanol group were fed with ethanol 8 g/kg/day. The ethanol+betaine groups were fed ethanol plus betaine (0.5 % w/v). Malondialdehyde levels and adenosine deaminase, superoxide dismutase, and xanthine oxidase activities were determined in pancreatic tissues of rats. Compared to control group, MDA levels increased significantly in the ethanol group (p<0.05). MDA levels in the ethanol+betaine group were significantly decreased compared to the ethanol group (p<0.05). ADA activity in the ethanol+betaine group decreased significantly when compared to the ethanol group (p<0.05). XO activities in ethanol-fed rats were decreased significantly compared to the control group (p<0.05). XO activity in the betaine group was increased significantly (p<0.05) compared to the ethanol group. SOD activity in the ethanol group decreased significantly compared to control group (p<0.001). SOD activity in the ethanol+betaine group decreased significantly (p<0.05) compared to the control group. We think that betaine, as a nutritional methylating agent, may be effective against ethanol-mediated oxidative stress in pancreatic tissue. PMID:20108209

  6. Perforin facilitates beta cell killing and regulates autoreactive CD8+ T-cell responses to antigen in mouse models of type 1 diabetes.

    PubMed

    Trivedi, Prerak; Graham, Kate L; Krishnamurthy, Balasubramaninan; Fynch, Stacey; Slattery, Robyn M; Kay, Thomas W H; Thomas, Helen E

    2016-04-01

    In type 1 diabetes, cytotoxic CD8(+) T lymphocytes (CTLs) directly interact with pancreatic beta cells through major histocompatibility complex class I. An immune synapse facilitates delivery of cytotoxic granules, comprised mainly of granzymes and perforin. Perforin deficiency protects the majority of non-obese diabetic (NOD) mice from autoimmune diabetes. Intriguingly perforin deficiency does not prevent diabetes in CD8(+) T-cell receptor transgenic NOD8.3 mice. We therefore investigated the importance of perforin-dependent killing via CTL-beta cell contact in autoimmune diabetes. Perforin-deficient CTL from NOD mice or from NOD8.3 mice were significantly less efficient at adoptive transfer of autoimmune diabetes into NODRag1(-/-) mice, confirming that perforin is essential to facilitate beta cell destruction. However, increasing the number of transferred in vitro-activated perforin-deficient 8.3 T cells reversed the phenotype and resulted in diabetes. Perforin-deficient NOD8.3 T cells were present in increased proportion in islets, and proliferated more in response to antigen in vivo indicating that perforin may regulate the activation of CTLs, possibly by controlling cytokine production. This was confirmed when we examined the requirement for direct interaction between beta cells and CD8(+) T cells in NOD8.3 mice, in which beta cells specifically lack major histocompatibility complex (MHC) class I through conditional deletion of β2-microglobulin. Although diabetes was significantly reduced, 40% of these mice developed diabetes, indicating that NOD8.3 T cells can kill beta cells in the absence of direct interaction. Our data indicate that although perforin delivery is the main mechanism that CTL use to destroy beta cells, they can employ alternative mechanisms to induce diabetes in a perforin-independent manner. PMID:26446877

  7. Effects of intravenous ethanol on basal bile-pancreatic secretion in nonalcoholic and alcohol-fed rats.

    PubMed

    Tiscornia, O M; Iovanna, J; Tumilasci, O; Perec, C J; Cresta, M A; Celener, D; Dreiling, D A

    1990-11-01

    In nonalcoholic (NA) and alcohol-fed rats (AF), intravenous-ethanol-induced percentage changes in bile-pancreatic-secretion (BPS) were evaluated, with and without gastric juice diversion (GJD) and with and without BPS duodenal recirculation (DR). Even with GJD, ethanol elicited a slight increase in BPS. These changes were greater in AF animals even when performed without GJD. When intravenous ethanol was given under conditions of GJD and DR, there were marked differences between the NA and AF animals in the ethanol-elicited post-plateau percentage changes of BPS. NA animals evidenced no significant difference from controls. But in the AF rats, ethanol triggered a marked and significant increase of flow, protein concentration, and output that became progressively greater in successive collection periods. It is postulated that without DR, and the resulting lack of negative duodeno-pancreatic reflexes (DPR), there occurs a change in reactivity to intravenous ethanol of the hypothalamic-bulbar nuclei (HBN) and in the mechanisms that modulate the flow of cholinergic impulses through the intrapancreatic ganglia (IPG). The postulated consequence is predominance (slight in NA rats receiving intravenous ethanol, greater in AF rats) in discharge of positive impulses from HBN and flowing unimpeded through the IPG to the "pancreon" units. In the NA animal with DR, ethanol may enhance BPS values, but in the AF rats, impairment of the negative DPR elicited by chronic alcohol intoxication might, after an acute intravenous ethanol injection, favor the discharge of positive impulses from the HBN flowing unimpeded through the IPG. In the AF rats also, ethanol would activate the nonnicotinic receptors of the neurons of the "antral," "duodenal," and "celiac" autonomic brains.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2079953

  8. Detection of C-Peptide in Urine as a Measure of Ongoing Beta Cell Function.

    PubMed

    McDonald, T J; Perry, M H

    2016-01-01

    C-peptide is a protein secreted by the pancreatic beta cells in equimolar quantities with insulin, following the cleavage of proinsulin into insulin. Measurement of C-peptide is used as a surrogate marker of endogenous insulin secretory capacity. Assessing C-peptide levels can be useful in classifying the subtype of diabetes as well as assessing potential treatment choices in the management of diabetes.Standard measures of C-peptide involve blood samples collected either fasted or, most often, after a fixed stimulus (such as oral glucose, mixed meal, or IV glucagon). Despite the established clinical utility of blood C-peptide measurement, its widespread use is limited. In many instances this is due to perceived practical restrictions associated with sample collection.Urine C-peptide measurement is an attractive noninvasive alternative to blood measures of beta-cell function. Urine C-peptide creatinine ratio measured in a single post stimulated sample has been shown to be a robust, reproducible measure of endogenous C-peptide which is stable for three days at room temperature when collected in boric acid. Modern high sensitivity immunoassay technologies have facilitated measurement of C-peptide down to single picomolar concentrations. PMID:27083170

  9. Chronic pancreatitis

    MedlinePlus

    Chronic pancreatitis - chronic; Pancreatitis - chronic - discharge; Pancreatic insufficiency - chronic; Acute pancreatitis - chronic ... abuse over many years. Repeated episodes of acute pancreatitis can lead to chronic pancreatitis. Genetics may be ...

  10. Pancreatic enlargement is evident in rats fed diets containing raw soybeans (Glycine max) or cowpeas (Vigna unguiculata) for 800 days but not in those fed diets based on kidney beans (Phaseolus vulgaris) or lupinseed (Lupinus angustifolius).

    PubMed

    Grant, G; Dorward, P M; Pusztai, A

    1993-12-01

    Pancreatic weights and composition were studied with rats fed diets containing raw legume seeds for up to 800 d. Rapid pancreatic enlargement was induced by dietary soybeans (Glycine max) (high Kunitz and Bowman-Birk trypsin inhibitor contents, moderate lectin content) during the initial 150 d. Over the next 200 d the rate of pancreatic growth was similar to that in controls. After 350 d a second period of rapid pancreatic growth occurred. Macroscopic pancreatic nodules were evident in a number of rats fed soybeans for 500 d or more. A similar pattern of pancreatic growth was observed in rats fed dietary cowpeas (Vigna unguiculata) (high Bowman-Birk inhibitor content, low lectin content). Extensive pancreatic growth was also found in young rats fed moderate dietary levels of kidney beans (Phaseolus vulgaris) (low Bowman-Birk inhibitor content, high lectin content). However, the trophic effects diminished with time, and from 100 d onwards, little enlargement was evident. Consumption of a lupinseed (Lupinus angustifolius) diet (low trypsin inhibitor, low lectin content) did not cause pancreatic enlargement. The initial pancreatic growth induced by dietary soybeans seemed to be due to the lectins and trypsin inhibitors, whereas the second period of pancreatic growth was possibly due primarily to the trypsin inhibitors. PMID:7505319

  11. Dietary soya beans and kidney beans stimulate secretion of cholecystokinin and pancreatic digestive enzymes in 400-day-old Hooded-Lister rats but only soya beans induce growth of the pancreas.

    PubMed

    Grant, G; Alonso, R; Edwards, J E; Murray, S

    2000-04-01

    The effects of age on cholecystokinin (CCK) release, pancreatic enzyme secretion, and growth of the pancreas mediated by dietary kidney beans or soya beans were evaluated in trials with 30-, 90-, 250-, and 400-day-old rats. Soya beans increased blood CCK and caused hypersecretion of digestive enzymes and rapid pancreatic growth in all rats. Kidney beans also elevated circulating CCK and stimulated enzyme secretion. However, with 90-, 250-, and 400-day-old rats, the secretory responses were attenuated. Furthermore, kidney beans did not induce pancreatic growth in 250- and 400-day-old rats. PMID:10766458

  12. Key Molecular Mechanisms of Chaiqinchengqi Decoction in Alleviating the Pulmonary Albumin Leakage Caused by Endotoxemia in Severe Acute Pancreatitis Rats.

    PubMed

    Wu, Wei; Luo, Ruijie; Lin, Ziqi; Xia, Qing; Xue, Ping

    2016-01-01

    To reveal the key molecular mechanisms of Chaiqinchengqi decoction (CQCQD) in alleviating the pulmonary albumin leakage caused by endotoxemia in severe acute pancreatitis (SAP) rats. Rats models of SAP endotoxemia-induced acute lung injury were established, the studies in vivo provided the important evidences that the therapy of CQCQD significantly ameliorated the increases in plasma levels of lipopolysaccharide (LPS), sCd14, and Lbp, the elevation of serum amylase level, the enhancements of systemic and pulmonary albumin leakage, and the depravation of airways indicators, thus improving respiratory dysfunction and also pancreatic and pulmonary histopathological changes. According to the analyses of rats pulmonary tissue microarray and protein-protein interaction network, c-Fos, c-Src, and p85α were predicted as the target proteins for CQCQD in alleviating pulmonary albumin leakage. To confirm these predictions, human umbilical vein endothelial cells were employed in in vitro studies, which provide the evidences that (1) LPS-induced paracellular leakage and proinflammatory cytokines release were suppressed by pretreatment with inhibitors of c-Src (PP1) or PI3K (LY294002) or by transfection with siRNAs of c-Fos; (2) fortunately, CQCQD imitated the actions of these selective inhibitions agents to inhibit LPS-induced high expressions of p-Src, p-p85α, and c-Fos, therefore attenuating paracellular leakage and proinflammatory cytokines release. PMID:27413385

  13. Key Molecular Mechanisms of Chaiqinchengqi Decoction in Alleviating the Pulmonary Albumin Leakage Caused by Endotoxemia in Severe Acute Pancreatitis Rats

    PubMed Central

    Wu, Wei; Luo, Ruijie; Lin, Ziqi; Xia, Qing

    2016-01-01

    To reveal the key molecular mechanisms of Chaiqinchengqi decoction (CQCQD) in alleviating the pulmonary albumin leakage caused by endotoxemia in severe acute pancreatitis (SAP) rats. Rats models of SAP endotoxemia-induced acute lung injury were established, the studies in vivo provided the important evidences that the therapy of CQCQD significantly ameliorated the increases in plasma levels of lipopolysaccharide (LPS), sCd14, and Lbp, the elevation of serum amylase level, the enhancements of systemic and pulmonary albumin leakage, and the depravation of airways indicators, thus improving respiratory dysfunction and also pancreatic and pulmonary histopathological changes. According to the analyses of rats pulmonary tissue microarray and protein-protein interaction network, c-Fos, c-Src, and p85α were predicted as the target proteins for CQCQD in alleviating pulmonary albumin leakage. To confirm these predictions, human umbilical vein endothelial cells were employed in in vitro studies, which provide the evidences that (1) LPS-induced paracellular leakage and proinflammatory cytokines release were suppressed by pretreatment with inhibitors of c-Src (PP1) or PI3K (LY294002) or by transfection with siRNAs of c-Fos; (2) fortunately, CQCQD imitated the actions of these selective inhibitions agents to inhibit LPS-induced high expressions of p-Src, p-p85α, and c-Fos, therefore attenuating paracellular leakage and proinflammatory cytokines release. PMID:27413385

  14. Expression of area-specific M2-macrophage phenotype by recruited rat monocytes in duct-ligation pancreatitis.

    PubMed

    Yu, Enqiao; Goto, Mataro; Ueta, Hisashi; Kitazawa, Yusuke; Sawanobori, Yasushi; Kariya, Taro; Sasaki, Masaru; Matsuno, Kenjiro

    2016-06-01

    Acute pancreatitis remains a disease of uncertain pathogenesis and no established specific therapy. Previously, we found a predominant increase and active proliferation of macrophages in the inflamed tissues of a rat duct-ligation pancreatitis model. To analyze the origin and possible role of these macrophages, we investigated their in situ cellular kinetics in a rat model of duct-ligation pancreatitis using a recently established method of multicolor immunostaining for macrophage markers and for proliferating cells with ethynyl deoxyuridine. To detect monocyte-derived macrophages, green fluorescent protein-transgenic (GFP(+)) leukocytes were transferred to monocyte-depleted recipients. In the inflamed pancreas, infiltrating macrophages were mainly two phenotypes, CD68(+)CD163(-) round cells and CD68(+)CD163(+) large polygonal cells, both of which showed active proliferation. In the interlobular area, the proportions of CD68(+)CD163(low) and CD68(+)CD163(high) cells increased over time. Most expressed the M2-macrophage markers CD206 and arginase 1. In contrast, in the interacinar area, CD68(+) cells did not upregulate CD163 and CD206, but ~30 % of them expressed the M1 marker nitric oxide synthase 2 on day 4. GFP(+)-recruited cells were primarily CD68(+)CD163(-) monocytes on day 1 and showed phenotypic changes similar to those of the monocyte non-depleted groups. In conclusion, infiltrating macrophages mostly formed two distinct subpopulations in different areas: monocyte-derived macrophages with the M2 phenotype in the interlobular area or non-M2 phenotype in the interacinar area. Involvement of resident macrophages might be minor in this model. These results are the first demonstration of an upregulated M2 phenotype in rat inflammatory monocytes, which may promote tissue repair. PMID:26860866

  15. Effect of the IkBα mutant gene delivery to mesenchymal stem cells on rat chronic pancreatitis.

    PubMed

    Qin, T; Liu, C J; Zhang, H W; Pan, Y F; Tang, Q; Liu, J K; Wang, Y Z; Hu, M X; Xue, F

    2014-01-01

    This study aimed to investigate the effect of inhibitors of the NF-kΒ alpha mutant gene (IkBaM) delivery to mensenchymal stem cells (MSCs) on rat chronic pancreatitis (CP). A total of 120 Sprague-Dawley rats were randomly divided into 6 groups of 20: Group A was injected with sterile saline solution, Group B was injected with allogenic MSCs, Group C1 was injected with allogenic IkBαM-MSCs cultured in vitro 4 h before CP modeling, Group C2 was injected with allogenic IkBαM-MSCs cultured in vitro during CP modeling, Group C3 was cultured with allogenic IkBαM-MSCs cultured in vitro 4 h after CP modeling, and Group D was injected with rAAV2-MSCs. Cytokine levels of ICAM-1, CTGF, IL-1, IL-6, IL-8, TNF-α, TIMP-1, TIMP-2, IL-10, FN, MMP-1, MMP-2, MMP-3, and MMP-9 were examined. The results indicated that allogenic IκBαM-MSCs could reduce pro-inflammatory cytokine levels and increase anti-inflammatory cytokine levels in CP. The allogenic IkBαM-MSCs reduced the activation and promoted the apoptosis of pancreatic stellate cells in the rat model of CP. IkBαM-MSCs influenced the proliferation and apoptosis of pancreatic stellate cells by regulating the activation of the PPAR, MAPK, mTOR, TGF-β, NOD-like receptor, Notch, WNT, TGF-β1-SMAD-2/3, and P53 signal transduction pathways. PMID:24535864

  16. Antioxidant Activity of Syringic Acid Prevents Oxidative Stress in l-arginine–Induced Acute Pancreatitis: An Experimental Study on Rats

    PubMed Central

    Cikman, Oztekin; Soylemez, Omer; Ozkan, Omer Faruk; Kiraz, Hasan Ali; Sayar, Ilyas; Ademoglu, Serkan; Taysi, Seyithan; Karaayvaz, Muammer

    2015-01-01

    The aim of this study was to investigate the possible protective role of antioxidant treatment with syringic acid (SA) on l-arginine–induced acute pancreatitis (AP) using biochemical and histopathologic approaches. A total of 30 rats were divided into 3 groups. The control group received normal saline intraperitoneally. The AP group was induced by 3.2 g/kg body weight l-arginine intraperitoneally, administered twice with an interval of 1 hour between administrations. The AP plus SA group, after having AP induced by 3.2 g/kg body weight l-arginine, was given SA (50 mg kg−1) in 2 parts within 24 hours. The rats were killed, and pancreatic tissue was removed and used in biochemical and histopathologic examinations. Compared with the control group, the mean pancreatic tissue total oxidant status level, oxidative stress index, and lipid hydroperoxide levels were significantly increased in the AP group, being 30.97 ± 7.13 (P < 0.05), 1.76 ± 0.34 (P < 0.0001), and 19.18 ± 4.91 (P < 0.01), respectively. However, mean total antioxidant status and sulfhydryl group levels were significantly decreased in the AP group compared with the control group, being 1.765 ± 0.21 (P < 0.0001) and 0.21 ± 0.04 (P < 0.0001), respectively. SA reduces oxidative stress markers and has antioxidant effects. It also augments antioxidant capacity in l-arginine–induced acute toxicity of pancreas in rats. PMID:26011211

  17. Physical exercise introduced after weaning enhances pancreatic islet responsiveness to glucose and potentiating agents in adult MSG-obese rats.

    PubMed

    Ribeiro, R A; Bonfleur, M L; Vanzela, E C; Zotti, A I; Scomparin, D X; Boschero, A C; Balbo, S L

    2014-08-01

    Physical exercise represents an alternative way to prevent and/or ameliorate chronic metabolic diseases. Disruption of sympathetic nervous system (SNS) activity contributes to adiposity in obese subjects. Here, we verified the preventive effect of swimming training upon adiposity, adrenal catecholamine storage, and pancreatic islet function in obese monosodium glutamate (MSG)-treated rats. Male neonatal Wistar rats received MSG (4 mg/g body weight) during the first 5 days of life and, at weaning, half of the rats were submitted to swimming training, 30 min/day, 3 days a week, until 90 days of age (exercised rats: MSGex). Half of the rats were used as controls (sedentary group, MSGsd). Exercise training (ET) decreased insulinemia and fat deposition in MSGex, and increased adrenal catecholamine content, compared with MSGsd rats. Insulinemia during the ivGTT was lower in MSGex rats, despite a lack of difference in glycemia. Swimming training enhanced insulin release in islets challenged by 2.8-8.3 mmol/l glucose, whereas, at supraphysiological glucose concentrations (11.1-16.7 mmol/l), MSGex islets secreted less insulin than MSGsd. No differences in insulin secretion were observed following l-arginine (Arg) or K(+) stimuli. In contrast, islets from MSGex rats secreted more insulin when exposed to carbachol (100 μmol/l), forskolin (10 μmol/l), or IBMX (1 mmol/l) at 8.3 mmol/l glucose. Additionally, MSGex islets presented a better epinephrine inhibition upon insulin release. These results demonstrate that ET prevented the onset of obesity in MSG rats, probably by enhancing adrenal catecholamine levels. ET ameliorates islet responsiveness to several compounds, as well as insulin peripheral action. PMID:24554535

  18. Copper addition prevents the inhibitory effects of interleukin 1-beta on rat pancreatic islets.

    PubMed

    Vinci, C; Caltabiano, V; Santoro, A M; Rabuazzo, A M; Buscema, M; Purrello, R; Rizzarelli, E; Vigneri, R; Purrello, F

    1995-01-01

    Since copper [Cu(II)] is a necessary cofactor for both intra-mitochondrial enzymes involved in energy production and hydroxyl scavenger enzymes, two hypothesised mechanisms for action of interleukin-I beta (IL-1 beta), we studied whether Cu(II) addition could prevent the inhibitory effect of IL-1 beta on insulin release and glucose oxidation in rat pancreatic islets. Islets were incubated with or without 50 U/ml IL-1 beta, in the presence or absence of various concentrations of Cu(II)-GHL (Cu(II) complexed with glycyl-L-histidyl-L-lysine, a tripeptide known to enhance copper uptake into cultured cells). CuSO4 (1-1000 ng/ml) was used as a control for Cu(II) effect when present as an inorganic salt. At the end of the incubation period, insulin secretion was evaluated in the presence of either 2.8 mmol/l (basal insulin secretion) or 16.7 mmol/l glucose (glucose-induced release). In control islets basal insulin secretion was 92.0 +/- 11.4 pg.islet-1 h-1 (mean +/- SEM, n = 7) and glucose-induced release was 2824.0 +/- 249.0 pg.islet-1 h-1. In islets pre-exposed to 50 U/ml IL-1 beta, basal insulin release was not significantly affected but glucose-induced insulin release was greatly reduced (841.2 +/- 76.9, n = 7, p < 0.005). In islets incubated with IL-1 beta and Cu-GHL (0.4 mumol/l, maximal effect) basal secretion was 119.0 +/- 13.1 pg.islet-1 h-1 and glucose-induced release was 2797.2 +/- 242.2, (n = 7, p < 0.01 in respect to islets exposed to IL-1 beta alone).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7744228

  19. Distinct antifibrogenic effects of erlotinib, sunitinib and sorafenib on rat pancreatic stellate cells

    PubMed Central

    Elsner, Anne; Lange, Falko; Fitzner, Brit; Heuschkel, Martin; Krause, Bernd Joachim; Jaster, Robert

    2014-01-01

    AIM: To study if three clinically available small molecule kinase inhibitors (SMI), erlotinib, sunitinib and sorafenib, exert antifibrogenic effects on pancreatic stellate cells (PSC) and analyze the basis of their action. METHODS: Cultured rat PSC were exposed to SMI. Cell proliferation and viability were assessed employing 5-bromo-2’-deoxyuridine incorporation assay and flow cytometry, respectively. 2-Deoxy-2-[18F] fluoroglucose (18F-FDG) uptake was measured to study metabolic activity. Exhibition of the myofibroblastic PSC phenotype was monitored by immunofluorescence analysis of α-smooth muscle actin (α-SMA) expression. Levels of mRNA were determined by real-time PCR, while protein expression and phosphorylation were analyzed by immunoblotting. Transforming growth factor-β1 (TGF-β1) levels in culture supernatants were quantified by ELISA. RESULTS: All three SMI inhibited cell proliferation and 18F-FDG uptake in a dose-dependent manner and without significant cytotoxic effects. Furthermore, additive effects of the drugs were observed. Immunoblot analysis showed that sorafenib and sunitib, but not erlotinib, efficiently blocked activation of the AKT pathway, while all three drugs displayed little effect on phosphorylation of ERK1/2. Cells treated with sorafenib or sunitinib expressed less interleukin-6 mRNA as well as less collagen type 1 mRNA and protein. Sorafenib was the only drug that also upregulated the expression of matrix metalloproteinase-2 and reduced the secretion of TGF-β1 protein. All three drugs showed insignificant or discordant effects on the mRNA and protein levels of α-SMA. CONCLUSION: The tested SMI, especially sorafenib, exert inhibitory effects on activated PSC, which should be further evaluated in preclinical studies. PMID:24976727

  20. Noncoding RNAs in Beta Cell Biology

    PubMed Central

    Singer, Ruth A.; Arnes, Luis; Sussel, Lori

    2015-01-01

    Purpose of Review The identification and characterization of essential islet transcription factors have improved our understanding of β cell development, provided insights into many of the cellular dysfunctions related to diabetes, and facilitated the successful generation of β cells from alternative cell sources. Recently, noncoding RNAs have emerged as a novel set of molecules that may represent missing components of the known islet regulatory pathways. The purpose of this review is to highlight studies that have implicated noncoding RNAs as important regulators of pancreas cell development and β cell function. Recent Findings Disruption of essential components of the microRNA processing machinery, in addition to misregulation of individual miRNAs, has revealed the importance of microRNAs in pancreas development and β cell function. Furthermore, over 1000 islet-specific long noncoding RNAs have been identified in mouse and human islets, suggesting that this class of noncoding molecules will also play important functional roles in the β cell. Summary The analysis of noncoding RNAs in the pancreas will provide important new insights into pancreatic regulatory processes that will improve our ability to understand and treat diabetes and may facilitate the generation of replacement β cells from alternative cell sources. PMID:25692923

  1. Artesunate ameliorates severe acute pancreatitis (SAP) in rats by inhibiting expression of pro-inflammatory cytokines and Toll-like receptor 4.

    PubMed

    Cen, Yanyan; Liu, Chao; Li, Xiaoli; Yan, Zifei; Kuang, Mei; Su, Yujie; Pan, Xichun; Qin, Rongxin; Liu, Xin; Zheng, Jiang; Zhou, Hong

    2016-09-01

    Severe acute pancreatitis (SAP) is a severe clinical condition with significant morbidity and mortality. Multiple organs dysfunction (MOD) is the leading cause of SAP-related death. The over-release of pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α is the underlying mechanism of MOD; however, there is no effective agent against the inflammation. Herein, artesunate (AS) was found to increase the survival of SAP rats significantly when injected with 3.5% sodium taurocholate into the biliopancreatic duct in a retrograde direction, improving their pancreatic pathology and decreasing serum amylase and pancreatic lipase activities along with substantially reduced pancreatic IL-1β and IL-6 release. In vitro, AS-pretreatment strongly inhibited IL-1β and IL-6 release and their mRNA expressions in the pancreatic acinar cells treated with lipopolysaccharide (LPS) but exerted little effect on TNF-α release. Additionally, AS reduced the mRNA expressions of Toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) p65 as well as their protein expressions in the pancreatic acinar cells. In conclusion, our results demonstrated that AS could significantly protect SAP rats, and this protection was related to the reduction of digestive enzyme activities and pro-inflammatory cytokine expressions via inhibition of TLR4/NF-κB signaling pathway. Therefore, AS may be considered as a potential therapeutic agent against SAP. PMID:27318790

  2. Melatonin metabolite, N(1)-acetyl-N(1)-formyl-5-methoxykynuramine (AFMK), attenuates acute pancreatitis in the rat: in vivo and in vitro studies.

    PubMed

    Jaworek, J; Szklarczyk, J; Bonior, J; Kot, M; Goralska, M; Pierzchalski, P; Reiter, R J; Czech, U; Tomaszewska, R

    2016-06-01

    Melatonin protects the pancreas from inflammation and free radical damage but the effect of the melatonin metabolite: N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) on acute pancreatitis is unknown. This study assessed the effects of AFMK on acute pancreatitis (AP) in the rats in vivo and on pancreatic cell line AR42J in vitro. AFMK (5, 10 or 20 mg/kg) was given intraperitoneally to the rats 30 min prior to the induction of AP by subcutaneous caerulein infusion (25 μg/kg). Lipid peroxidation products (MDA + 4-HNE) and the activity of an antioxidant enzyme glutathione peroxidase (GPx) were measured in pancreatic tissue. Blood samples were taken for evaluation of amylase activity and TNF-α concentration. GPx, TNF-α, proapoptotic Bax protein, antiapoptotic Bcl-2 protein and the executor of apoptosis, caspase-3, were determined by Western blot in AR42J cells subjected to AFMK or to melatonin (both used at 10(-12), 10(-10), or 10(-8)M), without or with addition of caerulein (10(-8)M). AP was confirmed by histological examination and by serum increases of amylase and TNF-α (by 800% and 300%, respectively). In AP rats, pancreatic MDA + 4-HNE levels were increased by 300%, whereas GPx was reduced by 50%. AFMK significantly diminished histological manifestations of AP, decreased serum amylase activity and TNF-α concentrations, reduced MDA + 4-HNE levels and augmented GPx in the pancreas of AP rats. In AR42J cells, AFMK combined with caerulein markedly increased protein signals for GPx, Bax, caspase-3 and reduced these for TNF-α and Bcl-2. In conclusion, AFMK significantly attenuated acute pancreatitis in the rat. This may relate to the antioxidative and anti-inflammatory effects of this molecule and possibly to the stimulation of proapoptotic signal transduction pathway. PMID:27512002

  3. Effects of the microbial secondary metabolites pyrrolnitrin, phenazine and patulin on INS-1 rat pancreatic β-cells.

    PubMed

    Nisr, Raid B; Russell, Mark A; Chrachri, Abdesslam; Moody, A John; Gilpin, Martyn L

    2011-11-01

    The effects on pancreatic β-cell viability and function of three microbial secondary metabolites pyrrolnitrin, phenazine and patulin were investigated, using the rat clonal pancreatic β-cell line, INS-1. Cells were exposed to 10-fold serial dilutions (range 0-10 μg mL(-1)) of the purified compounds for 2, 24 and 72 h. After 2 h exposure, only patulin (10 μg mL(-1)) was cytotoxic. All compounds showed significant cytotoxicity after 24 h. None of the compounds altered insulin secretion with 2 and 20 mM glucose after 2 h. However, after 24 h treatment, phenazine and pyrrolnitrin (10 and 100 ng mL(-1)) potentiated insulin production and glucose-stimulated insulin secretion, whereas patulin had no effect. Exposure (24 h) to either phenazine (100 ng mL(-1)) or pyrrolnitrin (10 ng mL(-1)) caused similar increases in the Ca(2+) content of INS-1 cells. The outward membrane current was inhibited after 24 h exposure to either phenazine (100 ng mL(-1)) or pyrrolnitrin (10 or 100 ng mL(-1)). This study presents novel data suggesting that high concentrations of pyrrolnitrin and phenazine are cytotoxic to pancreatic β-cells and thus possibly diabetogenic, whereas at lower concentrations these agents are nontoxic and may be insulinotropic. The possible role of such agents in the development of cystic fibrosis-related diabetes is discussed. PMID:22077225

  4. Usurping the mitochondrial supremacy: extramitochondrial sources of reactive oxygen intermediates and their role in beta cell metabolism and insulin secretion.

    PubMed

    Gray, Joshua P; Heart, Emma

    2010-05-01

    Insulin secretion from pancreatic beta cells is a process dependent on metabolism. While oxidative stress is a well-known inducer of beta cell toxicity and impairs insulin secretion, recent studies suggest that low levels of metabolically-derived reactive oxygen intermediates (ROI) also play a positive role in insulin secretion. Glucose metabolism is directly correlated with ROI production, particularly in beta cells in which glucose uptake is proportional to the extracellular concentration of glucose. Low levels of exogenously added ROI or quinones, which stimulate ROI production, positively affect insulin secretion, while antioxidants block insulin secretion, suggesting that ROI activate unidentified redox-sensitive signal transduction components within these cells. The mitochondria are one source of ROI: increased metabolic flux increases mitochondrial membrane potential resulting in electron leakage and adventitious ROI production. A second source of ROI are cytosolic and plasma membrane oxidoreductases which oxidize NAD(P)H and directly produce ROI through the reduction of molecular oxygen. The mechanism of ROI-mediated potentiation of insulin secretion remains an important topic for future study. PMID:20397883

  5. Roles of the co-culture of human umbilical cord Wharton’s jelly-derived mesenchymal stem cells with rat pancreatic cells in the treatment of rats with diabetes mellitus

    PubMed Central

    WANG, GUANGYU; LI, YONG; WANG, YU; DONG, YU; WANG, FU-SHENG; DING, YI; KANG, YUDONG; XU, XUYING

    2014-01-01

    The aim of the present study was to investigate the roles of the co-culture of human umbilical cord Wharton’s jelly-derived mesenchymal stem cells (hUC-MSCs) with rat pancreatic cells in the treatment of rats with diabetes mellitus. hUC-MSCs were isolated and passaged, followed by Transwell co-culture with rat pancreatic cells. The induced islet-like cell clusters were transplanted into the renal capsule in rats with streptozotocin (STZ)-induced diabetes mellitus. The effects of co-culture on blood glucose levels in rats were observed. The isolated hUC-MSCs expressed the specific surface markers, including cluster of differentiation 44 (CD44) (91.4%), CD29 (91.3%) and CD105 (99.2%). Following co-culture with hUC-MSCs for 7 and 10 days, the rat pancreatic cells were strongly stained by pancreatic and duodenal homeobox-1 and human insulin. The insulin and C-peptide concentrations were increased significantly compared to the pure culture group. One week following the transplantation of induced islet-like cells into the renal capsule, the blood glucose level of rats in the STZ experimental group was significantly lower than that of the STZ control group. There were notable 5-bromo-2′-deoxyuridine-positive nuclei and insulin-positive cytoplasm in the renal capsule following cell transplantation. Therefore, co-culture of hUC-MSCs with rat pancreatic cells can lower the blood glucose levels in rats with diabetes mellitus. PMID:25289028

  6. Pancreatic blood flow in experimental acute pancreatitis

    SciTech Connect

    Berry, A.R.; Millar, A.M.; Taylor, T.V.

    1982-05-01

    The etiology and pathogenesis of acute necrotizing hemorrhagic pancreatitis remain controversial. Recent work has suggested that an early fall in pancreatic blood flow, causing ischemia, may be the initiating factor. Using an established rat model of hemorrhagic pancreatitis and the fractional indicator distribution technique with /sup 86/RbCl, pancreatic blood flow and tissue perfusion have been measured at various times in the condition. Six groups of ten rats were studied: control sham operation and pancreatitis groups were sacrificed at 1, 6, and 24 hr. Pancreatic blood flow (% of cardiac output) and perfusion (blood flow/g tissue) were measured. Blood flow was increased by a maximum of 53% at 1 hr (P less than 0.001) and remained elevated for 24 hr, and perfusion was increased by a maximum of 70% (P less than 0.001) at 1 hr and remained elevated at 6 hr. Pancreatic perfusion declines after 6 hr due to increasing gland edema. The results demonstrate a significant increase in pancreatic blood flow and perfusion in experimentally induced acute pancreatitis, suggesting a primary inflammatory response, and refute the ischemic etiological theory.

  7. Effects of Tocotrienols on Insulin Secretion-Associated Genes Expression of Rat Pancreatic Islets in a Dynamic Culture

    PubMed Central

    Chia, Ling L.; Jantan, Ibrahim; Chua, Kien H.; Lam, Kok W.; Rullah, Kamal; Aluwi, Mohd F. M.

    2016-01-01

    Tocotrienols (T3) are well-known for their antioxidant properties besides showing therapeutic potential in clinical complications such as hyperlipidemia induced by diabetes. The aim of this study was to determine the effects of δ-T3, γ-T3, and α-T3 on insulin secretion-associated genes expression of rat pancreatic islets in a dynamic culture. Pancreatic islets freshly isolated from male Wistar rats were treated with T3 for 1 h at 37°C in a microfluidic system with continuous operation. The cells were collected for total RNA extraction and reverse-transcribed, followed by measurement of insulin secretion-associated genes expression using quantitative real-time polymerase chain reaction. Molecular docking experiments were performed to gain insights on how the T3 bind to the receptors. Short-term exposure of δ- and γ-T3 to pancreatic β cells in a stimulant glucose condition (16.7 mM) significantly regulated preproinsulin mRNA levels and insulin gene transcription. In contrast, α-T3 possessed less ability in the activation of insulin synthesis level. Essentially, potassium chloride (KCl), a β cell membrane depolarising agent added into the treatment further enhanced the insulin production. δ- and γ-T3 revealed significantly higher quantitative expression in most of the insulin secretion-associated genes groups containing 16.7 mM glucose alone and 16.7 mM glucose with 30 mM KCl ranging from 600 to 1200 μM (p < 0.05). The findings suggest the potential of δ-T3 in regulating insulin synthesis and glucose-stimulated insulin secretion through triggering pathway especially in the presence of KCl. PMID:27625609

  8. Effects of Tocotrienols on Insulin Secretion-Associated Genes Expression of Rat Pancreatic Islets in a Dynamic Culture.

    PubMed

    Chia, Ling L; Jantan, Ibrahim; Chua, Kien H; Lam, Kok W; Rullah, Kamal; Aluwi, Mohd F M

    2016-01-01

    Tocotrienols (T3) are well-known for their antioxidant properties besides showing therapeutic potential in clinical complications such as hyperlipidemia induced by diabetes. The aim of this study was to determine the effects of δ-T3, γ-T3, and α-T3 on insulin secretion-associated genes expression of rat pancreatic islets in a dynamic culture. Pancreatic islets freshly isolated from male Wistar rats were treated with T3 for 1 h at 37°C in a microfluidic system with continuous operation. The cells were collected for total RNA extraction and reverse-transcribed, followed by measurement of insulin secretion-associated genes expression using quantitative real-time polymerase chain reaction. Molecular docking experiments were performed to gain insights on how the T3 bind to the receptors. Short-term exposure of δ- and γ-T3 to pancreatic β cells in a stimulant glucose condition (16.7 mM) significantly regulated preproinsulin mRNA levels and insulin gene transcription. In contrast, α-T3 possessed less ability in the activation of insulin synthesis level. Essentially, potassium chloride (KCl), a β cell membrane depolarising agent added into the treatment further enhanced the insulin production. δ- and γ-T3 revealed significantly higher quantitative expression in most of the insulin secretion-associated genes groups containing 16.7 mM glucose alone and 16.7 mM glucose with 30 mM KCl ranging from 600 to 1200 μM (p < 0.05). The findings suggest the potential of δ-T3 in regulating insulin synthesis and glucose-stimulated insulin secretion through triggering pathway especially in the presence of KCl. PMID:27625609

  9. Histopathology and pathogenesis of caerulein-, duct ligation-, and arginine-induced acute pancreatitis in Sprague-Dawley rats and C57BL6 mice.

    PubMed

    Zhang, Jun; Rouse, Rodney L

    2014-09-01

    Three classical rodent models of acute pancreatitis were created in an effort to identify potential pre-clinical models of drug-induced pancreatitis (DIP) and candidate non-invasive biomarkers for improved detection of DIP. Study objectives included designing a lexicon to minimize bias by capturing normal variation and spontaneous and injury-induced changes while maintaining the ability to statistically differentiate degrees of change, defining morphologic anchors for novel pancreatic injury biomarkers, and improved understanding of mechanisms responsible for pancreatitis. Models were created in male Sprague-Dawley rats and C57BL6 mice through: 1) administration of the cholecystokinin analog, caerulein; 2) administration of arginine; 3) surgical ligation of the pancreatic duct. Nine morphologically detectable processes were used in the lexicon; acinar cell hypertrophy; acinar cell autophagy; acinar cell apoptosis; acinar cell necrosis; vascular injury; interstitial edema, inflammation and hemorrhage; fat necrosis; ductal changes; acinar cell atrophy. Criteria were defined for scoring levels (0 = absent, 1 = mild, 2 = moderate, 3 = severe) for each lexicon component. Consistent with previous studies, histopathology scores were significant greater in rats compared to mice at baseline and after treatment. The histopathology scores in caerulein and ligation-treated rats and mice were significantly greater than those of arginine-treated rats and mice. The present study supports a multifaceted pathogenesis for acute pancreatitis in which intra-acinar trypsinogen activation, damage to acinar cells, fat cells, and vascular cells as well as activation/degranulation of mast cells and activated macrophages all contribute to the initiation and/or progression of acute inflammation of the exocrine pancreas. PMID:24585404

  10. Accelerated Maturation of Human Stem Cell-Derived Pancreatic Progenitor Cells into Insulin-Secreting Cells in Immunodeficient Rats Relative to Mice

    PubMed Central

    Bruin, Jennifer E.; Asadi, Ali; Fox, Jessica K.; Erener, Suheda; Rezania, Alireza; Kieffer, Timothy J.

    2015-01-01

    Summary Pluripotent human embryonic stem cells (hESCs) are a potential source of transplantable cells for treating patients with diabetes. To investigate the impact of the host recipient on hESC-derived pancreatic progenitor cell maturation, cells were transplanted into immunodeficient SCID-beige mice or nude rats. Following the transplant, basal human C-peptide levels were consistently higher in mice compared with rats, but only rats showed robust meal- and glucose-responsive human C-peptide secretion by 19–21 weeks. Grafts from rats contained a higher proportion of insulin:glucagon immunoreactivity, fewer exocrine cells, and improved expression of mature β cell markers compared with mice. Moreover, ECM-related genes were enriched, the collagen network was denser, and blood vessels were more intricately integrated into the engrafted endocrine tissue in rats relative to mice. Overall, hESC-derived pancreatic progenitor cells matured faster in nude rats compared with SCID-beige mice, indicating that the host recipient can greatly influence the fate of immature pancreatic progenitor cells post-transplantation. PMID:26677767

  11. Pancreatitis - discharge

    MedlinePlus

    Chronic pancreatitis - discharge; Pancreatitis - chronic - discharge; Pancreatic insufficiency - discharge; Acute pancreatitis - discharge ... You were in the hospital because you have pancreatitis. This is a swelling of the pancreas. You ...

  12. Galunisertib (LY2157299), a transforming growth factor-β receptor I kinase inhibitor, attenuates acute pancreatitis in rats.

    PubMed

    Liu, X; Yu, M; Chen, Y; Zhang, J

    2016-08-01

    Galunisertib (LY2157299), a selective ATP-mimetic inhibitor of TGF-β receptor I (TGF-βRI), is the only known TGF-β pathway inhibitor. In the present study, we investigated the effect of galunisertib on taurocholate (TAC)-induced acute pancreatitis (AP) in rats, and the role of TGF-β and NF-κB signaling pathways. AP was induced by infusion of TAC into the pancreatic duct of Sprague-Dawley male rats (n=30). The rats (220±50 g) were administered galunisertib intragastrically [75 mg·kg-1·day-1 for 2 days (0 and 24 h)]. Serum IL-1β, IL-6, TNF-α, amylase (AMY), lipase (LIP), and myeloperoxidase (MPO) levels were measured by ELISA. NF-κB activity was detected by electrophoretic mobility shift assay (EMSA); NF-κBp65 and TGF-β1 proteins, as well as TGF-βRI and p-Smad2/3 proteins, were detected by western blot assay. Cell apoptosis was detected by TUNEL assay. H&E staining was used to evaluate the histopathological alterations of the pancreas. Galunisertib treatment attenuated the severity of AP and decreased the pancreatic histological score. In addition, number of apoptotic cells were significantly increased in the galunisertib-treated group (16.38±2.26) than in the AP group (8.14±1.27) and sham-operated group (1.82±0.73; P<0.05 and P<0.01, respectively). Galunisertib decreased the expression levels of TGF-βRI and p-Smad2/3 and inhibited NF-κB activation and p65 translocation compared with the sham-operated group. Furthermore, serum IL-1β, IL-6, TNF-α, AMY and LIP levels and tissue MPO activity were significantly decreased in the galunisertib-treated group. Our data demonstrate that galunisertib attenuates the severity of TAC-induced experimental AP in rats by inducing apoptosis in the pancreas, inhibiting the activation of TGF-β signals and NF-κB as well as the secretion of pro-inflammatory cytokines. PMID:27509307

  13. Galunisertib (LY2157299), a transforming growth factor-β receptor I kinase inhibitor, attenuates acute pancreatitis in rats

    PubMed Central

    Liu, X.; Yu, M.; Chen, Y.; Zhang, J.

    2016-01-01

    Galunisertib (LY2157299), a selective ATP-mimetic inhibitor of TGF-β receptor I (TGF-βRI), is the only known TGF-β pathway inhibitor. In the present study, we investigated the effect of galunisertib on taurocholate (TAC)-induced acute pancreatitis (AP) in rats, and the role of TGF-β and NF-κB signaling pathways. AP was induced by infusion of TAC into the pancreatic duct of Sprague-Dawley male rats (n=30). The rats (220±50 g) were administered galunisertib intragastrically [75 mg·kg-1·day-1 for 2 days (0 and 24 h)]. Serum IL-1β, IL-6, TNF-α, amylase (AMY), lipase (LIP), and myeloperoxidase (MPO) levels were measured by ELISA. NF-κB activity was detected by electrophoretic mobility shift assay (EMSA); NF-κBp65 and TGF-β1 proteins, as well as TGF-βRI and p-Smad2/3 proteins, were detected by western blot assay. Cell apoptosis was detected by TUNEL assay. H&E staining was used to evaluate the histopathological alterations of the pancreas. Galunisertib treatment attenuated the severity of AP and decreased the pancreatic histological score. In addition, number of apoptotic cells were significantly increased in the galunisertib-treated group (16.38±2.26) than in the AP group (8.14±1.27) and sham-operated group (1.82±0.73; P<0.05 and P<0.01, respectively). Galunisertib decreased the expression levels of TGF-βRI and p-Smad2/3 and inhibited NF-κB activation and p65 translocation compared with the sham-operated group. Furthermore, serum IL-1β, IL-6, TNF-α, AMY and LIP levels and tissue MPO activity were significantly decreased in the galunisertib-treated group. Our data demonstrate that galunisertib attenuates the severity of TAC-induced experimental AP in rats by inducing apoptosis in the pancreas, inhibiting the activation of TGF-β signals and NF-κB as well as the secretion of pro-inflammatory cytokines. PMID:27509307

  14. Beta-cell Assembly for the Quad Gas Sampling Detector

    SciTech Connect

    Cooper, Matthew W.; Bowyer, Ted W.; McIntyre, Justin I.; Hayes, James C.; Heimbigner, Tom R.; Ripplinger, Michael D.; Thompson, Robert C.

    2008-05-05

    The beta-cells used in the beta-gamma detector have taken time to develop and to standardize the assembly of them. In making the assembly routine it is important to have step by step assembly instructions as well as a list of potential problems and their solutions. This document attempts to accomplish these goals.

  15. Involvement of myristoylated alanine-rich C kinase substrate phosphorylation and translocation in cholecystokinin-induced amylase release in rat pancreatic acini.

    PubMed

    Satoh, Keitaro; Narita, Takanori; Katsumata-Kato, Osamu; Sugiya, Hiroshi; Seo, Yoshiteru

    2016-03-15

    Cholecystokinin (CCK) is a gastrointestinal hormone that induces exocytotic amylase release in pancreatic acinar cells. The activation of protein kinase C (PKC) is involved in the CCK-induced pancreatic amylase release. Myristoylated alanine-rich C kinase substrate (MARCKS) is a ubiquitously expressed substrate of PKC. MARCKS has been implicated in membrane trafficking in several cell types. The phosphorylation of MARCKS by PKC results in the translocation of MARCKS from the membrane to the cytosol. Here, we studied the involvement of MARCKS in the CCK-induced amylase release in rat pancreatic acini. Employing Western blotting, we detected MARCKS protein in the rat pancreatic acini. CCK induced MARCKS phosphorylation. A PKC-δ inhibitor, rottlerin, inhibited the CCK-induced MARCKS phosphorylation and amylase release. In the translocation assay, we also observed CCK-induced PKC-δ activation. An immunohistochemistry study showed that CCK induced MARCKS translocation from the membrane to the cytosol. When acini were lysed by a detergent, Triton X-100, CCK partially induced displacement of the MARCKS from the GM1a-rich detergent-resistant membrane fractions (DRMs) in which Syntaxin2 is distributed. A MARCKS-related peptide inhibited the CCK-induced amylase release. These findings suggest that MARCKS phosphorylation by PKC-δ and then MARCKS translocation from the GM1a-rich DRMs to the cytosol are involved in the CCK-induced amylase release in pancreatic acinar cells. PMID:26744470

  16. Pancreatic Transdifferentiation and Glucose-Regulated Production of Human Insulin in the H4IIE Rat Liver Cell Line

    PubMed Central

    Ren, Binhai; Tao, Chang; Swan, Margaret Anne; Joachim, Nichole; Martiniello-Wilks, Rosetta; Nassif, Najah T.; O’Brien, Bronwyn A.; Simpson, Ann M.

    2016-01-01

    Due to the limitations of current treatment regimes, gene therapy is a promising strategy being explored to correct blood glucose concentrations in diabetic patients. In the current study, we used a retroviral vector to deliver either the human insulin gene alone, the rat NeuroD1 gene alone, or the human insulin gene and rat NeuroD1 genes together, to the rat liver cell line, H4IIE, to determine if storage of insulin and pancreatic transdifferentiation occurred. Stable clones were selected and expanded into cell lines: H4IIEins (insulin gene alone), H4IIE/ND (NeuroD1 gene alone), and H4IIEins/ND (insulin and NeuroD1 genes). The H4IIEins cells did not store insulin; however, H4IIE/ND and H4IIEins/ND cells stored 65.5 ± 5.6 and 1475.4 ± 171.8 pmol/insulin/5 × 106 cells, respectively. Additionally, several β cell transcription factors and pancreatic hormones were expressed in both H4IIE/ND and H4IIEins/ND cells. Electron microscopy revealed insulin storage vesicles in the H4IIE/ND and H4IIEins/ND cell lines. Regulated secretion of insulin to glucose (0–20 mmol/L) was seen in the H4IIEins/ND cell line. The H4IIEins/ND cells were transplanted into diabetic immunoincompetent mice, resulting in normalization of blood glucose. This data shows that the expression of NeuroD1 and insulin in liver cells may be a useful strategy for inducing islet neogenesis and reversing diabetes. PMID:27070593

  17. Pancreatic Transdifferentiation and Glucose-Regulated Production of Human Insulin in the H4IIE Rat Liver Cell Line.

    PubMed

    Ren, Binhai; Tao, Chang; Swan, Margaret Anne; Joachim, Nichole; Martiniello-Wilks, Rosetta; Nassif, Najah T; O'Brien, Bronwyn A; Simpson, Ann M

    2016-01-01

    Due to the limitations of current treatment regimes, gene therapy is a promising strategy being explored to correct blood glucose concentrations in diabetic patients. In the current study, we used a retroviral vector to deliver either the human insulin gene alone, the rat NeuroD1 gene alone, or the human insulin gene and rat NeuroD1 genes together, to the rat liver cell line, H4IIE, to determine if storage of insulin and pancreatic transdifferentiation occurred. Stable clones were selected and expanded into cell lines: H4IIEins (insulin gene alone), H4IIE/ND (NeuroD1 gene alone), and H4IIEins/ND (insulin and NeuroD1 genes). The H4IIEins cells did not store insulin; however, H4IIE/ND and H4IIEins/ND cells stored 65.5 ± 5.6 and 1475.4 ± 171.8 pmol/insulin/5 × 10⁶ cells, respectively. Additionally, several β cell transcription factors and pancreatic hormones were expressed in both H4IIE/ND and H4IIEins/ND cells. Electron microscopy revealed insulin storage vesicles in the H4IIE/ND and H4IIEins/ND cell lines. Regulated secretion of insulin to glucose (0-20 mmol/L) was seen in the H4IIEins/ND cell line. The H4IIEins/ND cells were transplanted into diabetic immunoincompetent mice, resulting in normalization of blood glucose. This data shows that the expression of NeuroD1 and insulin in liver cells may be a useful strategy for inducing islet neogenesis and reversing diabetes. PMID:27070593

  18. Maternal antioxidants prevent beta cell apoptosis and promote formation of dual hormone-expressing endocrine cells in male offspring following fetal and neonatal nicotine exposure

    PubMed Central

    BRUIN, Jennifer E; WOYNILLOWICZ, Amanda K; HETTINGA, Bart P; TARNOPOLSKY, Mark A; MORRISON, Katherine M; GERSTEIN, Hertzel C; HOLLOWAY, Alison C

    2013-01-01

    Aim Fetal and neonatal nicotine exposure causes beta cell oxidative stress and apoptosis in neonates, leading to adult-onset dysglycemia. The goal of this study was to determine whether an antioxidant intervention could prevent nicotine-induced beta cell loss. Methods Nulliparous female Wistar rats received daily subcutaneous injections of either saline or nicotine bitartrate (1.0 mg/kg/d) for 2 weeks prior to mating until weaning. Nicotine-exposed dams received either normal chow or diet containing antioxidants (1000 IU/kg vitamin E, 0.25% w/w coenzyme Q10 and 0.1% w/w alpha-lipoic acid) during mating, pregnancy and lactation; saline-exposed dams received normal chow. Pancreas tissue was collected from male offspring at 3 weeks of age to measure beta cell fraction, apoptosis, proliferation and the presence of cells co-expressing insulin and glucagon. Results The birth weight of the offspring born to nicotine-exposed dams receiving dietary antioxidants was significantly reduced. Most interestingly, the antioxidant intervention to nicotine-exposed dams prevented the beta cell loss and apoptosis observed in nicotine exposed male offspring whose mothers did not receive antioxidants. Male pups born to nicotine-treated mothers receiving antioxidants also had a trend towards increased beta cell proliferation and a significant increase in islets containing insulin/glucagon bi-hormonal cells relative to the other two treatment groups. Conclusion This study demonstrates that exposure to maternal antioxidants protects beta cells from the damaging effects of nicotine thus preserving beta cell mass. PMID:22385833

  19. Beta cell adaptation in pregnancy: a tribute to Claes Hellerström

    PubMed Central

    2016-01-01

    Pregnancy is associated with a compensatory increase in beta cell mass. It is well established that somatolactogenic hormones contribute to the expansion both indirectly by their insulin antagonistic effects and directly by their mitogenic effects on the beta cells via receptors for prolactin and growth hormone expressed in rodent beta cells. However, the beta cell expansion in human pregnancy seems to occur by neogenesis of beta cells from putative progenitor cells rather than by proliferation of existing beta cells. Claes Hellerström has pioneered the research on beta cell growth for decades, but the mechanisms involved are still not clarified. In this review the information obtained in previous studies is recapitulated together with some of the current attempts to resolve the controversy in the field: identification of the putative progenitor cells, identification of the factors involved in the expansion of the beta cell mass in human pregnancy, and the relative roles of endocrine factors and nutrients. PMID:27055631

  20. Recent advances in the Okamoto model: the CD38-cyclic ADP-ribose signal system and the regenerating gene protein (Reg)-Reg receptor system in beta-cells.

    PubMed

    Okamoto, Hiroshi; Takasawa, Shin

    2002-12-01

    Twenty years ago, we first proposed our hypothesis on beta-cell damage and its prevention (the Okamoto model), according to which poly(ADP-ribose) synthetase/polymerase (PARP) activation is critically involved in the consumption of NAD(+), leading to energy depletion and cell death by necrosis. Recently, the model was reconfirmed by results using PARP knockout mice and has been recognized as providing the basis for necrotic death of various cells and tissues. Based on the model, we proposed two signal systems in beta-cells: one is the CD38-cyclic ADP-ribose (cADPR) signal system for insulin secretion, and the other is the regenerating gene protein (Reg)-Reg receptor system for beta-cell regeneration. The physiological and pathological significance of the two signal systems in a variety of cells and tissues as well as in pancreatic beta-cells has recently been recognized. Here, we describe the Okamoto model and its descendents, the CD38-cADPR signal system and the Reg-Reg receptor system, focusing on recent advances and how their significance came to light. Because PARP is involved in Reg gene transcription to induce beta-cell regeneration, and the PARP activation reduces the cellular NAD(+) to decrease the formation of cADPR (a second messenger for insulin secretion) and further to cause necrotic beta-cell death, PARP and its inhibitors have key roles in the induction of beta-cell regeneration, the maintenance of insulin secretion, and the prevention of beta-cell death. PMID:12475791

  1. In Vitro Differentiation of Human Umbilical Cord Blood CD133+Cells into Insulin Producing Cells in Co-Culture with Rat Pancreatic Mesenchymal Stem Cells

    PubMed Central

    Sahraneshin Samani, Fazel; Ebrahimi, Marzieh; Zandieh, Tahereh; Khoshchehreh, Reyhaneh; Baghaban Eslaminejad, Mohamadreza; Aghdami, Nasser; Baharvand, Hossein

    2015-01-01

    Objective Pancreatic stroma plays an important role in the induction of pancreatic cells by the use of close range signaling. In this respect, we presume that pancreatic mesenchymal cells (PMCs) as a fundamental factor of the stromal niche may have an effective role in differentiation of umbilical cord blood cluster of differentiation 133+ (UCB-CD133+) cells into newly-formed β-cells in vitro. Materials and Methods This study is an experimental research. The UCB-CD133+cells were purified by magnetic activated cell sorting (MACS) and differentiated into insulin producing cells (IPCs) in co-culture, both directly and indirectly with rat PMCs. Immunocytochemistry and enzyme linked immune sorbent assay (ELISA) were used to determine expression and production of insulin and C-peptide at the protein level. Results Our results demonstrated that UCB-CD133+differentiated into IPCs. Cells in islet-like clusters with (out) co-cultured with rat pancreatic stromal cells produced insulin and C-peptide and released them into the culture medium at the end of the induction protocol. However they did not respond well to glucose challenges. Conclusion Rat PMCs possibly affect differentiation of UCB-CD133+cells into IPCs by increasing the number of immature β-cells. PMID:26199900

  2. Pancreatic islet function in omega3 fatty acid-depleted rats: Glucose metabolism and nutrient-stimulated insulin release.

    PubMed

    Oguzhan, Berrin; Zhang, Ying; Louchami, Karim; Courtois, Philippe; Portois, Laurence; Chardigny, Jean-Michel; Malaisse, Willy J; Carpentier, Yvon A; Sener, Abdullah

    2006-06-01

    In order to gain information on the determinism of the perturbation of fuel homeostasis in situations characterized by a depletion in long-chain polyunsaturated omega3 fatty acids (omega3), the metabolic and hormonal status of omega3-depleted rats (second generation) was examined. When required, these rats were injected intravenously 120 min before sacrifice with a novel medium-chain triglyceride-fish oil emulsion able to provoke a rapid and sustained increase of the omega3 content in cell phospholipids. The measurement of plasma glucose, insulin, phospholipid, triglyceride, and unesterified fatty acid concentration indicated modest insulin resistance in the omega3-depleted rats. The plasma triglyceride and phospholipid concentrations were decreased in the omega3-depleted rats with abnormally low contribution of omega3 in both circulating and pancreatic islet lipids. The protein, insulin, and lipid content of the islets, as well as their intracellular and extracellular spaces, were little affected in the omega3-depleted rats. The metabolism of D-glucose in the islets of omega3-depleted rats was characterized by a lesser increase in D-[5-3H]glucose utilization and D-[U-14C]glucose oxidation in response to a given rise in hexose concentration and an abnormally low ratio between D-glucose oxidation and utilization. These abnormalities could be linked to an increased metabolism of endogenous fatty acids with resulting alteration of glucokinase kinetics. The release of insulin evoked by D-glucose, at a close-to-physiological concentration (8.3 mM), was increased in the omega3-depleted rats, this being considered as consistent with their insulin resistance. Relative to such a release, that evoked by a further rise in D-glucose concentration or by non-glucidic nutrients was abnormally high in omega3-depleted rats, and restored to a normal level after of the intravenous injection of the omega3-rich medium-chain triglyceride-fish oil emulsion. Because the latter procedure

  3. Unstable Expression of Commonly Used Reference Genes in Rat Pancreatic Islets Early after Isolation Affects Results of Gene Expression Studies

    PubMed Central

    Kosinová, Lucie; Cahová, Monika; Fábryová, Eva; Týcová, Irena; Koblas, Tomáš; Leontovyč, Ivan; Saudek, František; Kříž, Jan

    2016-01-01

    The use of RT-qPCR provides a powerful tool for gene expression studies; however, the proper interpretation of the obtained data is crucially dependent on accurate normalization based on stable reference genes. Recently, strong evidence has been shown indicating that the expression of many commonly used reference genes may vary significantly due to diverse experimental conditions. The isolation of pancreatic islets is a complicated procedure which creates severe mechanical and metabolic stress leading possibly to cellular damage and alteration of gene expression. Despite of this, freshly isolated islets frequently serve as a control in various gene expression and intervention studies. The aim of our study was to determine expression of 16 candidate reference genes and one gene of interest (F3) in isolated rat pancreatic islets during short-term cultivation in order to find a suitable endogenous control for gene expression studies. We compared the expression stability of the most commonly used reference genes and evaluated the reliability of relative and absolute quantification using RT-qPCR during 0–120 hrs after isolation. In freshly isolated islets, the expression of all tested genes was markedly depressed and it increased several times throughout the first 48 hrs of cultivation. We observed significant variability among samples at 0 and 24 hrs but substantial stabilization from 48 hrs onwards. During the first 48 hrs, relative quantification failed to reflect the real changes in respective mRNA concentrations while in the interval 48–120 hrs, the relative expression generally paralleled the results determined by absolute quantification. Thus, our data call into question the suitability of relative quantification for gene expression analysis in pancreatic islets during the first 48 hrs of cultivation, as the results may be significantly affected by unstable expression of reference genes. However, this method could provide reliable information from 48 hrs

  4. A small molecule that directs differentiation of human ESCs into the pancreatic lineage.

    PubMed

    Chen, Shuibing; Borowiak, Malgorzata; Fox, Julia L; Maehr, René; Osafune, Kenji; Davidow, Lance; Lam, Kelvin; Peng, Lee F; Schreiber, Stuart L; Rubin, Lee L; Melton, Douglas

    2009-04-01

    Stepwise differentiation from embryonic stem cells (ESCs) to functional insulin-secreting beta cells will identify key steps in beta-cell development and may yet prove useful for transplantation therapy for diabetics. An essential step in this schema is the generation of pancreatic progenitors--cells that express Pdx1 and produce all the cell types of the pancreas. High-content chemical screening identified a small molecule, (-)-indolactam V, that induces differentiation of a substantial number of Pdx1-expressing cells from human ESCs. The Pdx1-expressing cells express other pancreatic markers and contribute to endocrine, exocrine and duct cells, in vitro and in vivo. Further analyses showed that (-)-indolactam V works specifically at one stage of pancreatic development, inducing pancreatic progenitors from definitive endoderm. This study describes a chemical screening platform to investigate human ESC differentiation and demonstrates the generation of a cell population that is a key milepost on the path to making beta cells. PMID:19287398

  5. Reduced pancreatic protein secretion in response to cholecystokinin (CCK) in the obese Zucker rat co