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Sample records for insulin-secreting nit-1 cells

  1. Downregulation of lncRNA TUG1 Affects Apoptosis and Insulin Secretion in Mouse Pancreatic β Cells

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    Dan-dan Yin

    2015-03-01

    Full Text Available Background: Increasing evidence indicates that long noncoding RNAs (IncRNAs perform specific biological functions in diverse processes. Recent studies have reported that IncRNAs may be involved in β cell function. The aim of this study was to characterize the role of IncRNA TUG1 in mouse pancreatic β cell functioning both in vitro and in vivo. Methods: qRT-PCR analyses were performed to detect the expression of lncRNA TUG1 in different tissues. RNAi, MTT, TUNEL and Annexin V-FITC assays and western blot, GSIS, ELISA and immunochemistry analyses were performed to detect the effect of lncRNA TUG1 on cell apoptosis and insulin secretion in vitro and in vivo. Results: lncRNA TUG1 was highly expressed in pancreatic tissue compared with other organ tissues, and expression was dynamically regulated by glucose in Nit-1 cells. Knockdown of lncRNA TUG1 expression resulted in an increased apoptosis ratio and decreased insulin secretion in β cells both in vitro and in vivo . Immunochemistry analyses suggested decreased relative islet area after treatment with lncRNA TUG1 siRNA. Conclusion: Downregulation of lncRNA TUG1 expression affected apoptosis and insulin secretion in pancreatic β cells in vitro and in vivo. lncRNA TUG1 may represent a factor that regulates the function of pancreatic β cells.

  2. Downregulation of lncRNA TUG1 affects apoptosis and insulin secretion in mouse pancreatic β cells.

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    Yin, Dan-dan; Zhang, Er-bao; You, Liang-hui; Wang, Ning; Wang, Lin-tao; Jin, Fei-yan; Zhu, Ya-nan; Cao, Li-hua; Yuan, Qing-xin; De, Wei; Tang, Wei

    2015-01-01

    Increasing evidence indicates that long noncoding RNAs (IncRNAs) perform specific biological functions in diverse processes. Recent studies have reported that IncRNAs may be involved in β cell function. The aim of this study was to characterize the role of IncRNA TUG1 in mouse pancreatic β cell functioning both in vitro and in vivo. qRT-PCR analyses were performed to detect the expression of lncRNA TUG1 in different tissues. RNAi, MTT, TUNEL and Annexin V-FITC assays and western blot, GSIS, ELISA and immunochemistry analyses were performed to detect the effect of lncRNA TUG1 on cell apoptosis and insulin secretion in vitro and in vivo. lncRNA TUG1 was highly expressed in pancreatic tissue compared with other organ tissues, and expression was dynamically regulated by glucose in Nit-1 cells. Knockdown of lncRNA TUG1 expression resulted in an increased apoptosis ratio and decreased insulin secretion in β cells both in vitro and in vivo . Immunochemistry analyses suggested decreased relative islet area after treatment with lncRNA TUG1 siRNA. Downregulation of lncRNA TUG1 expression affected apoptosis and insulin secretion in pancreatic β cells in vitro and in vivo. lncRNA TUG1 may represent a factor that regulates the function of pancreatic β cells. © 2015 S. Karger AG, Basel.

  3. Synaptotagmin-7 phosphorylation mediates GLP-1-dependent potentiation of insulin secretion from β-cells

    DEFF Research Database (Denmark)

    Wu, Bingbing; Wei, Shunhui; Petersen, Natalia

    2015-01-01

    Glucose stimulates insulin secretion from β-cells by increasing intracellular Ca(2+). Ca(2+) then binds to synaptotagmin-7 as a major Ca(2+) sensor for exocytosis, triggering secretory granule fusion and insulin secretion. In type-2 diabetes, insulin secretion is impaired; this impairment...... is ameliorated by glucagon-like peptide-1 (GLP-1) or by GLP-1 receptor agonists, which improve glucose homeostasis. However, the mechanism by which GLP-1 receptor agonists boost insulin secretion remains unclear. Here, we report that GLP-1 stimulates protein kinase A (PKA)-dependent phosphorylation...... of synaptotagmin-7 at serine-103, which enhances glucose- and Ca(2+)-stimulated insulin secretion and accounts for the improvement of glucose homeostasis by GLP-1. A phospho-mimetic synaptotagmin-7 mutant enhances Ca(2+)-triggered exocytosis, whereas a phospho-inactive synaptotagmin-7 mutant disrupts GLP-1...

  4. Antioxidant effect of mogrosides against oxidative stress induced by palmitic acid in mouse insulinoma NIT-1 cells

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    Xu, Q.; Chen, S.Y.; Deng, L.D.; Feng, L.P.; Huang, L.Z.; Yu, R.R. [Department of Pharmacy, Guilin Medical University, Guilin (China)

    2013-11-18

    Excessive oxidative stress in pancreatic β cells, caused by glucose and fatty acids, is associated with the pathogenesis of type 2 diabetes. Mogrosides have shown antioxidant and antidiabetic activities in animal models of diabetes, but the underlying mechanisms remain unclear. This study evaluated the antioxidant effect of mogrosides on insulinoma cells under oxidative stress caused by palmitic acid, and investigated the underlying molecular mechanisms. Mouse insulinoma NIT-1 cells were cultured in medium containing 0.75 mM palmitic acid, mimicking oxidative stress. The effects of 1 mM mogrosides were determined with the dichlorodihydrofluorescein diacetate assay for intracellular reactive oxygen species (ROS) and FITC-Annexin V/PI assay for cell apoptosis. Expression of glucose transporter-2 (GLUT2) and pyruvate kinase was determined by semi-quantitative reverse-transcription polymerase chain reaction. Palmitic acid significantly increased intracellular ROS concentration 2-fold (P<0.05), and decreased expression of GLUT2 (by 60%, P<0.05) and pyruvate kinase (by 80%, P<0.05) mRNAs in NIT-1 cells. Compared with palmitic acid, co-treatment with 1 mM mogrosides for 48 h significantly reduced intracellular ROS concentration and restored mRNA expression levels of GLUT2 and pyruvate kinase. However, mogrosides did not reverse palmitic acid-induced apoptosis in NIT-1 cells. Our results indicate that mogrosides might exert their antioxidant effect by reducing intracellular ROS and regulating expression of genes involved in glucose metabolism. Further research is needed to achieve a better understanding of the signaling pathway involved in the antioxidant effect of mogrosides.

  5. Urea impairs β cell glycolysis and insulin secretion in chronic kidney disease

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    Koppe, Laetitia; Nyam, Elsa; Vivot, Kevin; Manning Fox, Jocelyn E.; Dai, Xiao-Qing; Nguyen, Bich N.; Attané, Camille; Moullé, Valentine S.; MacDonald, Patrick E.; Ghislain, Julien

    2016-01-01

    Disorders of glucose homeostasis are common in chronic kidney disease (CKD) and are associated with increased mortality, but the mechanisms of impaired insulin secretion in this disease remain unclear. Here, we tested the hypothesis that defective insulin secretion in CKD is caused by a direct effect of urea on pancreatic β cells. In a murine model in which CKD is induced by 5/6 nephrectomy (CKD mice), we observed defects in glucose-stimulated insulin secretion in vivo and in isolated islets. Similarly, insulin secretion was impaired in normal mouse and human islets that were cultured with disease-relevant concentrations of urea and in islets from normal mice treated orally with urea for 3 weeks. In CKD mouse islets as well as urea-exposed normal islets, we observed an increase in oxidative stress and protein O-GlcNAcylation. Protein O-GlcNAcylation was also observed in pancreatic sections from CKD patients. Impairment of insulin secretion in both CKD mouse and urea-exposed islets was associated with reduced glucose utilization and activity of phosphofructokinase 1 (PFK-1), which could be reversed by inhibiting O-GlcNAcylation. Inhibition of O-GlcNAcylation also restored insulin secretion in both mouse models. These results suggest that insulin secretory defects associated with CKD arise from elevated circulating levels of urea that increase islet protein O-GlcNAcylation and impair glycolysis. PMID:27525435

  6. Intracellular serotonin modulates insulin secretion from pancreatic beta-cells by protein serotonylation.

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    Nils Paulmann

    2009-10-01

    Full Text Available While serotonin (5-HT co-localization with insulin in granules of pancreatic beta-cells was demonstrated more than three decades ago, its physiological role in the etiology of diabetes is still unclear. We combined biochemical and electrophysiological analyses of mice selectively deficient in peripheral tryptophan hydroxylase (Tph1-/- and 5-HT to show that intracellular 5-HT regulates insulin secretion. We found that these mice are diabetic and have an impaired insulin secretion due to the lack of 5-HT in the pancreas. The pharmacological restoration of peripheral 5-HT levels rescued the impaired insulin secretion in vivo. These findings were further evidenced by patch clamp experiments with isolated Tph1-/- beta-cells, which clearly showed that the secretory defect is downstream of Ca(2+-signaling and can be rescued by direct intracellular application of 5-HT via the clamp pipette. In elucidating the underlying mechanism further, we demonstrate the covalent coupling of 5-HT by transglutaminases during insulin exocytosis to two key players in insulin secretion, the small GTPases Rab3a and Rab27a. This renders them constitutively active in a receptor-independent signaling mechanism we have recently termed serotonylation. Concordantly, an inhibition of such activating serotonylation in beta-cells abates insulin secretion. We also observed inactivation of serotonylated Rab3a by enhanced proteasomal degradation, which is in line with the inactivation of other serotonylated GTPases. Our results demonstrate that 5-HT regulates insulin secretion by serotonylation of GTPases within pancreatic beta-cells and suggest that intracellular 5-HT functions in various microenvironments via this mechanism in concert with the known receptor-mediated signaling.

  7. Induction of insulin secretion in engineered liver cells by nitric oxide

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    Özcan Sabire

    2007-10-01

    Full Text Available Abstract Background Type 1 Diabetes Mellitus results from an autoimmune destruction of the pancreatic beta cells, which produce insulin. The lack of insulin leads to chronic hyperglycemia and secondary complications, such as cardiovascular disease. The currently approved clinical treatments for diabetes mellitus often fail to achieve sustained and optimal glycemic control. Therefore, there is a great interest in the development of surrogate beta cells as a treatment for type 1 diabetes. Normally, pancreatic beta cells produce and secrete insulin only in response to increased blood glucose levels. However in many cases, insulin secretion from non-beta cells engineered to produce insulin occurs in a glucose-independent manner. In the present study we engineered liver cells to produce and secrete insulin and insulin secretion can be stimulated via the nitric oxide pathway. Results Expression of either human insulin or the beta cell specific transcription factors PDX-1, NeuroD1 and MafA in the Hepa1-6 cell line or primary liver cells via adenoviral gene transfer, results in production and secretion of insulin. Although, the secretion of insulin is not significantly increased in response to high glucose, treatment of these engineered liver cells with L-arginine stimulates insulin secretion up to three-fold. This L-arginine-mediated insulin release is dependent on the production of nitric oxide. Conclusion Liver cells can be engineered to produce insulin and insulin secretion can be induced by treatment with L-arginine via the production of nitric oxide.

  8. Intracellular and extracellular adenosine triphosphate in regulation of insulin secretion from pancreatic β cells (β).

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    Wang, Chunjiong; Geng, Bin; Cui, Qinghua; Guan, Youfei; Yang, Jichun

    2014-03-01

    Adenosine triphosphate (ATP) synthesis and release in mitochondria play critical roles in regulating insulin secretion in pancreatic β cells. Mitochondrial dysfunction is mainly characterized by a decrease in ATP production, which is a central event in the progression of pancreatic β cell dysfunction and diabetes. ATP has been demonstrated to regulate insulin secretion via several pathways: (i) Intracellular ATP directly closes ATP-sensitive potassium channel to open L-type calcium channel, leading to an increase in free cytosolic calcium levels and exocytosis of insulin granules; (ii) A decrease in ATP production is always associated with an increase in production of reactive oxygen species, which exerts deleterious effects on pancreatic β cell survival and insulin secretion; and (iii) ATP can be co-secreted with insulin from pancreatic β cells, and the released ATP functions as an autocrine signal to modulate insulin secretory process via P2 receptors on the cell membrane. In this review, the recent findings regarding the role and mechanism of ATP synthesis and release in regulation of insulin secretion from pancreatic β cells will be summarized and discussed. © 2013 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

  9. Sirt1 regulates insulin secretion by repressing UCP2 in pancreatic beta cells.

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    Laura Bordone

    2006-02-01

    Full Text Available Sir2 and insulin/IGF-1 are the major pathways that impinge upon aging in lower organisms. In Caenorhabditis elegans a possible genetic link between Sir2 and the insulin/IGF-1 pathway has been reported. Here we investigate such a link in mammals. We show that Sirt1 positively regulates insulin secretion in pancreatic beta cells. Sirt1 represses the uncoupling protein (UCP gene UCP2 by binding directly to the UCP2 promoter. In beta cell lines in which Sirt1 is reduced by SiRNA, UCP2 levels are elevated and insulin secretion is blunted. The up-regulation of UCP2 is associated with a failure of cells to increase ATP levels after glucose stimulation. Knockdown of UCP2 restores the ability to secrete insulin in cells with reduced Sirt1, showing that UCP2 causes the defect in glucose-stimulated insulin secretion. Food deprivation induces UCP2 in mouse pancreas, which may occur via a reduction in NAD (a derivative of niacin levels in the pancreas and down-regulation of Sirt1. Sirt1 knockout mice display constitutively high UCP2 expression. Our findings show that Sirt1 regulates UCP2 in beta cells to affect insulin secretion.

  10. Sodium arsenite impairs insulin secretion and transcription in pancreatic β-cells

    International Nuclear Information System (INIS)

    Diaz-Villasenor, Andrea; Sanchez-Soto, M. Carmen; Cebrian, Mariano E.; Ostrosky-Wegman, Patricia; Hiriart, Marcia

    2006-01-01

    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 β-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 β-cells. Cells were treated with 0.5, 1, 2, 5 and 10 μM sodium arsenite and incubated for 72 and 144 h. The highest dose tested (10 μM) decreased β-cell viability, by 33% and 83%, respectively. Insulin secretion and mRNA expression were evaluated in the presence of 1 and 5 μM sodium arsenite. Basal insulin secretion, in 5.6 mM glucose, was not significantly affected by 1 or 5 μM treatment for 72 h, but basal secretion was reduced when cells were exposed to 5 μM 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 μM sodium arsenite during 72 h. Our data suggest that arsenic may contribute to the development of diabetes mellitus by impairing pancreatic β-cell functions, particularly insulin synthesis and secretion

  11. Leucine metabolism in regulation of insulin secretion from pancreatic beta cells

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    Yang, Jichun; Chi, Yujing; Burkhardt, Brant R.; Guan, Youfei; Wolf, Bryan A

    2010-01-01

    Leucine, a the branched-chain amino acids that must be supplied in daily diet, plays an important role in controlling protein synthesis and regulating cell metabolism in various cell types. In pancreatic β cells, leucine acutely stimulates insulin secretion by serving as both metabolic fuel and allosteric activator of glutamate dehydrogenase to enhance glutaminolysis. Leucine has also been shown to regulate gene transcription and protein synthesis in pancreatic islet β cells via both mTOR-dep...

  12. Activation of PPARd and RXRa stimulates fatty acid oxidatin and insulin secretion inpancreatic beta-cells

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    Børgesen, Michael; Ravnskjær, Kim; Frigerio, Francesca

    as a central effector of unsaturated fatty acids in pancreatic ß-cells. Interestingly, activation of PPARd increases basal as well as glucose-stimulated insulin secretion of INS-1E cells. This increase is further potentiated by RXR agonists. This observation suggests that PPARd may mediate some of the positive......ACTIVATION OF PPARd AND RXRa STIMULATES FATTY ACID OXIDATION AND INSULIN SECRETION IN PANCREATIC b-CELLS Michael Boergesen1, Kim Ravnskjaer2, Francesca Frigerio3, Allan E. Karlsen4, Pierre Maechler3 and Susanne Mandrup1 1 Department of Biochemistry and Molecular Biology, University of Southern...... of genes as PPARd specific agonists and stimulates ß-oxidation. Importantly, oleate-induction of gene expression and ß-oxidation in INS-1E cells is abolished by knock-down of PPARd using adenoviral transfer of shRNA. Thus, PPARd appears to be a central regulator of fatty acid metabolism as well...

  13. Pancreatic β-Cell Electrical Activity and Insulin Secretion: of Mice and Men

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    Rorsman, Patrik; Ashcroft, Frances M

    2018-01-01

    The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycaemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM. PMID:29212789

  14. Dual role of proapoptotic BAD in insulin secretion and beta cell survival

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    Danial, Nika N.; Walensky, Loren D.; Zhang, Chen-Yu; Choi, Cheol Soo; Fisher, Jill K.; Molina, Anthony J. A.; Datta, Sandeep Robert; Pitter, Kenneth L.; Bird, Gregory H.; Wikstrom, Jakob D.; Deeney, Jude T.; Robertson, Kirsten; Morash, Joel; Kulkarni, Ameya; Neschen, Susanne

    2008-01-01

    The proapoptotic BCL-2 family member BAD resides in a glucokinase-containing complex that regulates glucose-driven mitochondrial respiration. Here, we present genetic evidence of a physiologic role for BAD in glucose-stimulated insulin secretion by beta cells. This novel function of BAD is specifically dependent upon the phosphorylation of its BH3 sequence, previously defined as an essential death domain. We highlight the pharmacologic relevance of phosphorylated BAD BH3 by using cell-permeab...

  15. Geniposide regulates glucose-stimulated insulin secretion possibly through controlling glucose metabolism in INS-1 cells.

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    Jianhui Liu

    Full Text Available Glucose-stimulated insulin secretion (GSIS is essential to the control of metabolic fuel homeostasis. The impairment of GSIS is a key element of β-cell failure and one of causes of type 2 diabetes mellitus (T2DM. Although the KATP channel-dependent mechanism of GSIS has been broadly accepted for several decades, it does not fully describe the effects of glucose on insulin secretion. Emerging evidence has suggested that other mechanisms are involved. The present study demonstrated that geniposide enhanced GSIS in response to the stimulation of low or moderately high concentrations of glucose, and promoted glucose uptake and intracellular ATP levels in INS-1 cells. However, in the presence of a high concentration of glucose, geniposide exerted a contrary role on both GSIS and glucose uptake and metabolism. Furthermore, geniposide improved the impairment of GSIS in INS-1 cells challenged with a high concentration of glucose. Further experiments showed that geniposide modulated pyruvate carboxylase expression and the production of intermediates of glucose metabolism. The data collectively suggest that geniposide has potential to prevent or improve the impairment of insulin secretion in β-cells challenged with high concentrations of glucose, likely through pyruvate carboxylase mediated glucose metabolism in β-cells.

  16. Superoxide generation is diminished during glucose-stimulated insulin secretion in INS-1E cells

    Czech Academy of Sciences Publication Activity Database

    Ježek, Petr; Hlavatá, Lydie; Špaček, Tomáš

    2008-01-01

    Roč. 275, Suppl.1 (2008), s. 310-310 ISSN 1742-464X. [FEBS Congress /33./ and IUBMB Conference /11./. 28.06.2008-03.07.2008, Athens] R&D Projects: GA MZd(CZ) NR7917; GA AV ČR(CZ) IAA500110701 Institutional research plan: CEZ:AV0Z50110509 Keywords : cpo1 * superoxide production * glucose-stimulated insulin secretion * INS-1E cells Subject RIV: ED - Physiology

  17. Jinlida granule inhibits palmitic acid induced-intracellular lipid accumulation and enhances autophagy in NIT-1 pancreatic β cells through AMPK activation.

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    Wang, Dingkun; Tian, Min; Qi, Yuan; Chen, Guang; Xu, Lijun; Zou, Xin; Wang, Kaifu; Dong, Hui; Lu, Fuer

    2015-02-23

    Jinlida granule (JLDG), composed of seventeen Chinese medical herbs, is a widely used Chinese herbal prescription for treating diabetes mellitus. However, the mechanism underlying this effect remains unclear. To determine the main components in JLDG and to explore the effect of JLDG on autophagy and lipid accumulation in NIT-1 pancreatic β cells exposed to politic acid (PA) through AMP activated protein kinase (AMPK) signaling pathway. JLDG was prepared and the main components contained in the granules were identified by ultra performance liquid chromatography (UPLC) fingerprint. Intracellular lipid accumulation in NIT-1 cells was induced by culturing with medium containing PA. Intracellular lipid droplets were observed by Oil Red O staining and triglyceride (TG) content was measured by colorimetric assay. The formation of autophagosomes was observed under transmission electron microscope. The expression of AMPK and phospho-AMPK (pAMPK) proteins as well as its downstream fatty acid metabolism-related proteins (fatty acid synthase, FAS; acetyl-coA carboxylase, ACC; carnitine acyltransferase 1, CPT-1) and autophagy-related genes (mammal target of rapamycin, mTOR; tuberous sclerosis complex 1, TSC1; microtubule-associated protein 1 light chain 3, LC3-II) were determined by Western blot. The expression of sterol regulating element binding protein 1c (SREBP-1c) mRNA was examined by real time PCR (RT-PCR). Our data showed that JLDG could significantly reduce PA-induced intracellular lipid accumulation in NIT-1 pancreatic β cells. This effect was associated with increased protein expression of pAMPK and AMPK in NIT-1 cells. Treatment with JLDG also decreased the expression of AMPK downstream lipogenic genes (SREBP-1c mRNA, FAS and ACC proteins) whereas increased the expression of fatty acid oxidation gene (CPT-1 protein). Additionally, JLDG-treated cells displayed a markedly increase in the number of autophagosomes which was accompanied by the down-regulation of m

  18. Targeting development of incretin-producing cells increases insulin secretion

    DEFF Research Database (Denmark)

    Petersen, Natalia; Reimann, Frank; van Es, Johan H

    2015-01-01

    the number of intestinal L cells, which produce GLP-1, is an alternative strategy to augment insulin responses and improve glucose tolerance. Blocking the NOTCH signaling pathway with the γ-secretase inhibitor dibenzazepine increased the number of L cells in intestinal organoid-based mouse and human culture...... of the development of incretin-producing cells in the intestine has potential as a therapeutic strategy to improve glycemic control....

  19. Dual role of proapoptotic BAD in insulin secretion and beta cell survival.

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    Danial, Nika N; Walensky, Loren D; Zhang, Chen-Yu; Choi, Cheol Soo; Fisher, Jill K; Molina, Anthony J A; Datta, Sandeep Robert; Pitter, Kenneth L; Bird, Gregory H; Wikstrom, Jakob D; Deeney, Jude T; Robertson, Kirsten; Morash, Joel; Kulkarni, Ameya; Neschen, Susanne; Kim, Sheene; Greenberg, Michael E; Corkey, Barbara E; Shirihai, Orian S; Shulman, Gerald I; Lowell, Bradford B; Korsmeyer, Stanley J

    2008-02-01

    The proapoptotic BCL-2 family member BAD resides in a glucokinase-containing complex that regulates glucose-driven mitochondrial respiration. Here, we present genetic evidence of a physiologic role for BAD in glucose-stimulated insulin secretion by beta cells. This novel function of BAD is specifically dependent upon the phosphorylation of its BH3 sequence, previously defined as an essential death domain. We highlight the pharmacologic relevance of phosphorylated BAD BH3 by using cell-permeable, hydrocarbon-stapled BAD BH3 helices that target glucokinase, restore glucose-driven mitochondrial respiration and correct the insulin secretory response in Bad-deficient islets. Our studies uncover an alternative target and function for the BAD BH3 domain and emphasize the therapeutic potential of phosphorylated BAD BH3 mimetics in selectively restoring beta cell function. Furthermore, we show that BAD regulates the physiologic adaptation of beta cell mass during high-fat feeding. Our findings provide genetic proof of the bifunctional activities of BAD in both beta cell survival and insulin secretion.

  20. Nuclear SREBP-1a causes loss of pancreatic β-cells and impaired insulin secretion

    International Nuclear Information System (INIS)

    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

    2009-01-01

    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 β-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, ΒΕΤΑ2, MafA, and IRS-2 were suppressed, partially explaining the loss and dysfunction of β-cell mass. The transgenic mice on a high fat/high sucrose diet still exhibited impaired insulin secretion and continuous β-cell growth defect. Therefore, nuclear SREBP-1a, even at a low level, strongly disrupts β-cell mass and function.

  1. Glycated albumin suppresses glucose-induced insulin secretion by impairing glucose metabolism in rat pancreatic β-cells

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    Muto Takashi

    2011-04-01

    Full Text Available Abstract Background Glycated albumin (GA is an Amadori product used as a marker of hyperglycemia. In this study, we investigated the effect of GA on insulin secretion from pancreatic β cells. Methods Islets were collected from male Wistar rats by collagenase digestion. Insulin secretion in the presence of non-glycated human albumin (HA and GA was measured under three different glucose concentrations, 3 mM (G3, 7 mM (G7, and 15 mM (G15, with various stimulators. Insulin secretion was measured with antagonists of inducible nitric oxide synthetase (iNOS, and the expression of iNOS-mRNA was investigated by real-time PCR. Results Insulin secretion in the presence of HA and GA was 20.9 ± 3.9 and 21.6 ± 5.5 μU/3 islets/h for G3 (P = 0.920, and 154 ± 9.3 and 126.1 ± 7.3 μU/3 islets/h (P = 0.046, for G15, respectively. High extracellular potassium and 10 mM tolbutamide abrogated the inhibition of insulin secretion by GA. Glyceraldehyde, dihydroxyacetone, methylpyruvate, GLP-1, and forskolin, an activator of adenylate cyclase, did not abrogate the inhibition. Real-time PCR showed that GA did not induce iNOS-mRNA expression. Furthermore, an inhibitor of nitric oxide synthetase, aminoguanidine, and NG-nitro-L-arginine methyl ester did not abrogate the inhibition of insulin secretion. Conclusion GA suppresses glucose-induced insulin secretion from rat pancreatic β-cells through impairment of intracellular glucose metabolism.

  2. Redifferentiation of insulin-secreting cells after in vitro expansion of adult human pancreatic islet tissue

    International Nuclear Information System (INIS)

    Lechner, Andreas; Nolan, Anna L.; Blacken, Robyn A.; Habener, Joel F.

    2005-01-01

    Cellular replacement therapy holds promise for the treatment of diabetes mellitus but donor tissue is severely limited. Therefore, we investigated whether insulin-secreting cells could be differentiated in vitro from a monolayer of cells expanded from human donor pancreatic islets. We describe a three-step culture protocol that allows for the efficient generation of insulin-producing cell clusters from in vitro expanded, hormone-negative cells. These clusters express insulin at levels of up to 34% that of average freshly isolated human islets and secrete C-peptide upon membrane depolarization. They also contain cells expressing the other major islet hormones (glucagon, somatostatin, and pancreatic polypeptide). The source of the newly differentiated endocrine cells could either be indigenous stem/progenitor cells or the proliferation-associated dedifferentiation and subsequent redifferentiation of mature endocrine cells. The in vitro generated cell clusters may be efficacious in providing islet-like tissue for transplantation into diabetic recipients

  3. Huntingtin-interacting protein 14 is a type 1 diabetes candidate protein regulating insulin secretion and β-cell apoptosis

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    Berchtold, Lukas Adrian; Størling, Zenia Marian; Ortis, Fernanda

    2011-01-01

    Type 1 diabetes (T1D) is a complex disease characterized by the loss of insulin-secreting β-cells. Although the disease has a strong genetic component, and several loci are known to increase T1D susceptibility risk, only few causal genes have currently been identified. To identify disease...... genes in T1D, including the INS gene. An unexpected top-scoring candidate gene was huntingtin-interacting protein (HIP)-14/ZDHHC17. Immunohistochemical analysis of pancreatic sections demonstrated that HIP14 is almost exclusively expressed in insulin-positive cells in islets of Langerhans. RNAi...... knockdown experiments established that HIP14 is an antiapoptotic protein required for β-cell survival and glucose-stimulated insulin secretion. Proinflammatory cytokines (IL-1β and IFN-γ) that mediate β-cell dysfunction in T1D down-regulated HIP14 expression in insulin-secreting INS-1 cells and in isolated...

  4. Nicotinamide induces differentiation of embryonic stem cells into insulin-secreting cells

    International Nuclear Information System (INIS)

    Vaca, Pilar; Berna, Genoveva; Araujo, Raquel; Carneiro, Everardo M.; Bedoya, Francisco J.; Soria, Bernat; Martin, Franz

    2008-01-01

    The poly(ADP-ribose) polymerase (PARP) inhibitor, nicotinamide, induces differentiation and maturation of fetal pancreatic cells. In addition, we have previously reported evidence that nicotinamide increases the insulin content of cells differentiated from embryonic stem (ES) cells, but the possibility of nicotinamide acting as a differentiating agent on its own has never been completely explored. Islet cell differentiation was studied by: (i) X-gal staining after neomycin selection; (ii) BrdU studies; (iii) single and double immunohistochemistry for insulin, C-peptide and Glut-2; (iv) insulin and C-peptide content and secretion assays; and (v) transplantation of differentiated cells, under the kidney capsule, into streptozotocin (STZ)-diabetic mice. Here we show that undifferentiated mouse ES cells treated with nicotinamide: (i) showed an 80% decrease in cell proliferation; (ii) co-expressed insulin, C-peptide and Glut-2; (iii) had values of insulin and C-peptide corresponding to 10% of normal mouse islets; (iv) released insulin and C-peptide in response to stimulatory glucose concentrations; and (v) after transplantation into diabetic mice, normalized blood glucose levels over 7 weeks. Our data indicate that nicotinamide decreases ES cell proliferation and induces differentiation into insulin-secreting cells. Both aspects are very important when thinking about cell therapy for the treatment of diabetes based on ES cells

  5. Subcellular localization, mobility, and kinetic activity of glucokinase in glucose-responsive insulin-secreting cells.

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    Stubbs, M; Aiston, S; Agius, L

    2000-12-01

    We investigated the subcellular localization, mobility, and activity of glucokinase in MIN6 cells, a glucose-responsive insulin-secreting beta-cell line. Glucokinase is present in the cytoplasm and a vesicular/granule compartment that is partially colocalized with insulin granules. The granular staining of glucokinase is preserved after permeabilization of the cells with digitonin. There was no evidence for changes in distribution of glucokinase between the cytoplasm and the granule compartment during incubation of the cells with glucose. The rate of release of glucokinase and of phosphoglucoisomerase from digitonin-permeabilized cells was slower when cells were incubated at an elevated glucose concentration (S0.5 approximately 15 mmol/l). This effect of glucose was counteracted by competitive inhibitors of glucokinase (5-thioglucose and mannoheptulose) but was unaffected by fructose analogs and may be due to changes in cell shape or conformation of the cytoskeleton that are secondary to glucose metabolism. Based on the similar release of glucokinase and phosphoglucoisomerase, we found no evidence for specific binding of cytoplasmic digitonin-extractable glucokinase. The affinity of beta-cells for glucose is slightly lower than that in cell extracts and, unlike that in hepatocytes, is unaffected by fructose, tagatose, or a high-K+ medium, which is consistent with the lack of change in glucokinase distribution or release. We conclude that glucokinase is present in two locations, cytoplasm and the granular compartment, and that it does not translocate between them. This conclusion is consistent with the lack of adaptive changes in the glucose phosphorylation affinity. The glucokinase activity associated with the insulin granules may have a role in either direct or indirect coupling between glucose phosphorylation and insulin secretion.

  6. Activation of transmembrane bile acid receptor TGR5 stimulates insulin secretion in pancreatic β cells

    International Nuclear Information System (INIS)

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

    2012-01-01

    Highlights: ► G protein coupled receptor TGR5 is expressed in mouse and human islets. ► TGR5 is coupled to activation of Gs and Ca 2+ release via cAMP/Epac/PLC-ε pathway. ► Activation of TGR5 by bile salts and selective ligands causes insulin secretion. ► 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 β cells. In the present study, we have identified the expression of TGR5 in pancreatic β cell line MIN6 and also in mouse and human pancreatic islets. TGR5 selective ligands, oleanolic acid (OA) and INT-777 selectively activated Gα s and caused an increase in intracellular cAMP and Ca 2+ . OA and INT-777 also increased phosphoinositide (PI) hydrolysis and the increase was blocked by NF449 (a selective Gα 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 s /cAMP/Ca 2+ pathway. 8-pCPT-2′-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 β cells regulates insulin secretion and highlights the importance of ongoing therapeutic strategies targeting TGR5 in the control of glucose homeostasis.

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

    Energy Technology Data Exchange (ETDEWEB)

    Reinhardt, Florian; Schultz, Julia; Waterstradt, Rica; Baltrusch, Simone, E-mail: simone.baltrusch@med.uni-rostock.de

    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. -- Highlights: •Down-regulation of Drp1 in INS1 cells reduces mitochondrial fusion protein expression. •Mitochondrial membrane potential in INS1 cells is diminished after Drp1 down-regulation. •Mitochondria become elongated after down-regulation of Drp1 in beta cells. •Down-regulation of

  8. Interleukin-33-Activated Islet-Resident Innate Lymphoid Cells Promote Insulin Secretion through Myeloid Cell Retinoic Acid Production.

    Science.gov (United States)

    Dalmas, Elise; Lehmann, Frank M; Dror, Erez; Wueest, Stephan; Thienel, Constanze; Borsigova, Marcela; Stawiski, Marc; Traunecker, Emmanuel; Lucchini, Fabrizio C; Dapito, Dianne H; Kallert, Sandra M; Guigas, Bruno; Pattou, Francois; Kerr-Conte, Julie; Maechler, Pierre; Girard, Jean-Philippe; Konrad, Daniel; Wolfrum, Christian; Böni-Schnetzler, Marianne; Finke, Daniela; Donath, Marc Y

    2017-11-21

    Pancreatic-islet inflammation contributes to the failure of β cell insulin secretion during obesity and type 2 diabetes. However, little is known about the nature and function of resident immune cells in this context or in homeostasis. Here we show that interleukin (IL)-33 was produced by islet mesenchymal cells and enhanced by a diabetes milieu (glucose, IL-1β, and palmitate). IL-33 promoted β cell function through islet-resident group 2 innate lymphoid cells (ILC2s) that elicited retinoic acid (RA)-producing capacities in macrophages and dendritic cells via the secretion of IL-13 and colony-stimulating factor 2. In turn, local RA signaled to the β cells to increase insulin secretion. This IL-33-ILC2 axis was activated after acute β cell stress but was defective during chronic obesity. Accordingly, IL-33 injections rescued islet function in obese mice. Our findings provide evidence that an immunometabolic crosstalk between islet-derived IL-33, ILC2s, and myeloid cells fosters insulin secretion. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Role of aryl hydrocarbon receptor nuclear translocator in KATP channel-mediated insulin secretion in INS-1 insulinoma cells

    International Nuclear Information System (INIS)

    Kim, Ji-Seon; Zheng Haifeng; Kim, Sung Joon; Park, Jong-Wan; Park, Kyong Soo; Ho, Won-Kyung; Chun, Yang-Sook

    2009-01-01

    Aryl hydrocarbon receptor nuclear translocator (ARNT) has been known to participate in cellular responses to xenobiotic and hypoxic stresses, as a common partner of aryl hydrocarbon receptor and hypoxia inducible factor-1/2α. Recently, it was reported that ARNT is essential for adequate insulin secretion in response to glucose input and that its expression is downregulated in the pancreatic islets of diabetic patients. In the present study, the authors addressed the mechanism by which ARNT regulates insulin secretion in the INS-1 insulinoma cell line. In ARNT knock-down cells, basal insulin release was elevated, but insulin secretion was not further stimulated by a high-glucose challenge. Electrophysiological analyses revealed that glucose-dependent membrane depolarization was impaired in these cells. Furthermore, K ATP channel activity and expression were reduced. Of two K ATP channel subunits, Kir6.2 was found to be positively regulated by ARNT at the mRNA and protein levels. Based on these results, the authors suggest that ARNT expresses K ATP channel and by so doing regulates glucose-dependent insulin secretion.

  10. High passage MIN6 cells have impaired insulin secretion with impaired glucose and lipid oxidation.

    Directory of Open Access Journals (Sweden)

    Kim Cheng

    Full Text Available Type 2 diabetes is a metabolic disorder characterized by the inability of beta-cells to secrete enough insulin to maintain glucose homeostasis. MIN6 cells secrete insulin in response to glucose and other secretagogues, but high passage (HP MIN6 cells lose their ability to secrete insulin in response to glucose. We hypothesized that metabolism of glucose and lipids were defective in HP MIN6 cells causing impaired glucose stimulated insulin secretion (GSIS. HP MIN6 cells had no first phase and impaired second phase GSIS indicative of global functional impairment. This was coupled with a markedly reduced ATP content at basal and glucose stimulated states. Glucose uptake and oxidation were higher at basal glucose but ATP content failed to increase with glucose. HP MIN6 cells had decreased basal lipid oxidation. This was accompanied by reduced expressions of Glut1, Gck, Pfk, Srebp1c, Ucp2, Sirt3, Nampt. MIN6 cells represent an important model of beta cells which, as passage numbers increased lost first phase but retained partial second phase GSIS, similar to patients early in type 2 diabetes onset. We believe a number of gene expression changes occurred to produce this defect, with emphasis on Sirt3 and Nampt, two genes that have been implicated in maintenance of glucose homeostasis.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Divya P.; Rajagopal, Senthilkumar; Mahavadi, Sunila [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Mirshahi, Faridoddin [Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Grider, John R. [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Murthy, Karnam S., E-mail: skarnam@vcu.edu [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Sanyal, Arun J., E-mail: asanyal@mcvh-vcu.edu [Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA (United States)

    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.

  12. The voltage-gated proton channel Hv1 is expressed in pancreatic islet β-cells and regulates insulin secretion

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qing [Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071 (China); Che, Yongzhe [School of Medicine, Nankai University, Tianjin 300071 (China); Li, Qiang; Zhang, Shangrong [Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071 (China); Gao, Ying-Tang [Key Laboratory of Artificial Cell, Third Central Clinical College of Tianjin Medical University, Tianjin 300170 (China); Wang, Yifan; Wang, Xudong; Xi, Wang; Zuo, Weiyan [Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071 (China); Li, Shu Jie, E-mail: shujieli@nankai.edu.cn [Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071 (China)

    2015-12-25

    The voltage-gated proton channel Hv1 is a potent acid extruder that participates in the extrusion of the intracellular acid. Here, we showed for the first time, Hv1 is highly expressed in mouse and human pancreatic islet β-cells, as well as β-cell lines. Imaging studies demonstrated that Hv1 resides in insulin-containing granules in β-cells. Knockdown of Hv1 with RNA interference significantly reduces glucose- and K{sup +}-induced insulin secretion in isolated islets and INS-1 (832/13) β-cells and has an impairment on glucose- and K{sup +}-induced intracellular Ca{sup 2+} homeostasis. Our data demonstrated that the expression of Hv1 in pancreatic islet β-cells regulates insulin secretion through regulating Ca{sup 2+} homeostasis.

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Advanced glycation end products impair glucose-induced insulin secretion from rat pancreatic β-cells.

    Science.gov (United States)

    Hachiya, Hiroyuki; Miura, Yoshikazu; Inoue, Ken-Ichi; Park, Kyung Hwa; Takeuchi, Masayoshi; Kubota, Keiichi

    2014-02-01

    Advanced glycation end products (AGEs) are derivative compounds generated from non-enzymatic glycosylation and oxidation. In comparison with glucose-derived AGEs (Glu-AGEs), glyceraldehyde-derived AGEs (Glycer-AGEs) have stronger toxicity to living systems. In this study, we compared the effects of Glu-AGE and Glycer-AGE on insulin secretion. Rat pancreatic islets were isolated by collagenase digestion and primary-cultured in the presence of 0.1 mg/ml bovine serum albumin (BSA) or 0.1 mg/ml Glu-AGE or Glycer-AGE-albumin. After 48 h of culture, we performed an insulin secretion test and identified the defects by a battery of rescue experiments [corrected]. Also, mRNA expression of genes associated with insulin secretion was measured. Insulin secretion induced by a high glucose concentration was 164.1 ± 6.0, 124.4 ± 4.4 (P < 0.05) and 119.8 ± 7.1 (P < 0.05) μU/3 islets/h in the presence of BSA, Glu-AGE, and Glycer-AGE, respectively. Inhibition of insulin secretion by Glu-AGE or Glycer-AGE was rescued by a high extracellular potassium concentration, tolbutamide and α-ketoisocaproic acid, but not by glyceraldehyde, dihydroxacetone, methylpyruvate, glucagon-like peptide-1 and acetylcholine. Glu-AGE or Glycer-AGE reduced the expression of the malate dehydrogenase (Mdh1/2) gene, which plays a critical role in the nicotinamide adenine dinucleotide (NADH) shuttle. Despite its reported cytotoxicity, the effects of Glycer-AGE on insulin secretion are similar to those of Glu-AGE. © 2013 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

  15. Mitochondrial Dysfunction Contributes to Impaired Insulin Secretion in INS-1 Cells with Dominant-negative Mutations of HNF-1α and in HNF-1α-deficient Islets*

    OpenAIRE

    Pongratz, Rebecca L.; Kibbey, Richard G.; Kirkpatrick, Clare L.; Zhao, Xiaojian; Pontoglio, Marco; Yaniv, Moshe; Wollheim, Claes B.; Shulman, Gerald I.; Cline, Gary W.

    2009-01-01

    Maturity Onset Diabetes of the Young-type 3 (MODY-3) has been linked to mutations in the transcription factor hepatic nuclear factor (HNF)-1α, resulting in deficiency in glucose-stimulated insulin secretion. In INS-1 cells overexpressing doxycycline-inducible HNF-1α dominant-negative (DN-) gene mutations, and islets from Hnf-1α knock-out mice, insulin secretion was impaired in response to glucose (15 mm) and other nutrient secretagogues. Decreased rates of insulin secretion in response to glu...

  16. Quantification of beta-cell function during IVGTT in Type II and non-diabetic subjects: assessment of insulin secretion by mathematical methods

    DEFF Research Database (Denmark)

    Kjems, L L; Vølund, A; Madsbad, Sten

    2001-01-01

    AIMS/HYPOTHESIS: We compared four methods to assess their accuracy in measuring insulin secretion during an intravenous glucose tolerance test in patients with Type II (non-insulin-dependent) diabetes mellitus and with varying beta-cell function and matched control subjects. METHODS: Eight control...... subjects and eight Type II diabetic patients underwent an intravenous glucose tolerance test with tolbutamide and an intravenous bolus injection of C-peptide to assess C-peptide kinetics. Insulin secretion rates were determined by the Eaton deconvolution (reference method), the Insulin SECretion method...... (ISEC) based on population kinetic parameters as well as one-compartment and two-compartment versions of the combined model of insulin and C-peptide kinetics. To allow a comparison of the accuracy of the four methods, fasting rates and amounts of insulin secreted during the first phase (0-10 min...

  17. FTO Inhibits Insulin Secretion and Promotes NF-κB Activation through Positively Regulating ROS Production in Pancreatic β cells.

    Directory of Open Access Journals (Sweden)

    Hong-Qi Fan

    Full Text Available FTO (Fat mass and obesity-associated is associated with increased risk of obesity and type 2 diabetes incurrence. Pancreas islet β cells dysfunction and insulin resistance are major causes of type 2 diabetes. However, whether FTO plays an important functional role in pancreatic β cells as well as the related molecular mechanism is still unclear. In the present study, the tissue expression profile of FTO was firstly determined using quantitative PCR and western blot. FTO is widely expressed in various tissues and presented with relative high expression in pancreas tissue, especially in endocrine pancreas. FTO overexpression in MIN6 cells achieved by lentivirus delivery significantly inhibits insulin secretion in the presence of glucose stimulus as well as KCl. FTO silence has no effect on insulin secretion of MIN6 cells. However, FTO overexpression doesn't affect the transcription of insulin gene. Furthermore, reactive oxygen species (ROS production and NF-κB activation are significantly promoted by FTO overexpression. Inhibition of intracellular ROS production by N-acetyl-L-cysteine (NAC can alleviate NF-κB activation and restore the insulin secretion mediated by FTO overexpression. A whole transcript-microarray is employed to analyze the differential gene expression mediated by FTO overexpression. The genes which are modulated by FTO are involved in many important biological pathways such as G-protein coupled receptor signaling and NF-κB signaling. Therefore, our study indicates that FTO may contribute to pancreas islet β cells dysfunction and the inhibition of FTO activity is a potential target for the treatment of diabetes.

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

    Science.gov (United States)

    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.

  19. The Influence of Stabilized Deconjugated Ursodeoxycholic Acid on Polymer-Hydrogel System of Transplantable NIT-1 Cells.

    Science.gov (United States)

    Mooranian, Armin; Negrulj, Rebecca; Al-Salami, Hani

    2016-05-01

    The encapsulation of pancreatic β-cells in biocompatible matrix has generated great interest in diabetes treatment. Our work has shown improved microcapsules when incorporating the bile acid ursodeoxycholic acid (UDCA), in terms of morphology and cell viability although cell survival remained low. Thus, the study aimed at incorporating the polyelectrolytes polyallylamine (PAA) and poly-l-ornithine (PLO), with the polymer sodium alginate (SA) and the hydrogel ultrasonic gel (USG) with UDCA and examined cell viability and functionality post microencapsulation. Microcapsules without (control) and with UDCA (test) were produced using 1% PLO, 2.5% PAA, 1.8% SA and 4.5% USG. Pancreatic β-cells were microencapsulated and the microcapsules' morphology, surface components, cellular and bile acid distribution, osmotic and mechanical stability as well as biocompatibilities, insulin production, bioenergetics and the inflammatory response were tested. Incorporation of UDCA at 4% into a PLO-PAA-SA formulation system increased cell survival (p acid UDCA (4%) has good potential in cell transplantation and diabetes treatment.

  20. Olive Component Oleuropein Promotes β-Cell Insulin Secretion and Protects β-Cells from Amylin Amyloid-Induced Cytotoxicity.

    Science.gov (United States)

    Wu, Ling; Velander, Paul; Liu, Dongmin; Xu, Bin

    2017-09-26

    Oleuropein, a natural product derived from olive leaves, has reported anti-diabetic functions. However, detailed molecular mechanisms for how it affects β-cell functions remain poorly understood. Here, we present evidence that oleuropein promotes glucose-stimulated insulin secretion (GSIS) in β-cells. The effect is dose-dependent and stimulates the ERK/MAPK signaling pathway. We further demonstrated that oleuropein inhibits the cytotoxicity induced by amylin amyloids, a hallmark feature of type 2 diabetes. We demonstrated that these dual functions are structure-specific: we identified the 3-hydroxytyrosol moiety of oleuropein as the main functional entity responsible for amyloid inhibition, but the novel GSIS function requires the entire structure scaffold of the molecule.

  1. Rates of insulin secretion in INS-1 cells are enhanced by coupling to anaplerosis and Kreb’s cycle flux independent of ATP synthesis

    International Nuclear Information System (INIS)

    Cline, Gary W.; Pongratz, Rebecca L.; Zhao, Xiaojian; Papas, Klearchos K.

    2011-01-01

    Highlights: ► We studied media effects on mechanisms of insulin secretion of INS-1 cells. ► Insulin secretion was higher in DMEM than KRB despite identical ATP synthesis rates. ► Insulin secretion rates correlated with rates of anaplerosis and TCA cycle. ► Mitochondria metabolism and substrate cycles augment secretion signal of ATP. -- Abstract: Mechanistic models of glucose stimulated insulin secretion (GSIS) established in minimal media in vitro, may not accurately describe the complexity of coupling metabolism with insulin secretion that occurs in vivo. As a first approximation, we have evaluated metabolic pathways in a typical growth media, DMEM as a surrogate in vivo medium, for comparison to metabolic fluxes observed under the typical experimental conditions using the simple salt-buffer of KRB. Changes in metabolism in response to glucose and amino acids and coupling to insulin secretion were measured in INS-1 832/13 cells. Media effects on mitochondrial function and the coupling efficiency of oxidative phosphorylation were determined by fluorometrically measured oxygen consumption rates (OCRs) combined with 31 P NMR measured rates of ATP synthesis. Substrate preferences and pathways into the TCA cycle, and the synthesis of mitochondrial 2nd messengers by anaplerosis were determined by 13 C NMR isotopomer analysis of the fate of [U- 13 C] glucose metabolism. Despite similar incremental increases in insulin secretion, the changes of OCR in response to increasing glucose from 2.5 to 15 mM were blunted in DMEM relative to KRB. Basal and stimulated rates of insulin secretion rates were consistently higher in DMEM, while ATP synthesis rates were identical in both DMEM and KRB, suggesting greater mitochondrial uncoupling in DMEM. The relative rates of anaplerosis, and hence synthesis and export of 2nd messengers from the mitochondria were found to be similar in DMEM to those in KRB. And, the correlation of total PC flux with insulin secretion rates in DMEM

  2. Rates of insulin secretion in INS-1 cells are enhanced by coupling to anaplerosis and Kreb's cycle flux independent of ATP synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Cline, Gary W., E-mail: gary.cline@yale.edu [The Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520 (United States); Department of Surgery, University of Minnesota-Twin Cities, Minneapolis, MN 55455 (United States); Pongratz, Rebecca L.; Zhao, Xiaojian [The Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520 (United States); Papas, Klearchos K. [Department of Surgery, University of Minnesota-Twin Cities, Minneapolis, MN 55455 (United States)

    2011-11-11

    Highlights: Black-Right-Pointing-Pointer We studied media effects on mechanisms of insulin secretion of INS-1 cells. Black-Right-Pointing-Pointer Insulin secretion was higher in DMEM than KRB despite identical ATP synthesis rates. Black-Right-Pointing-Pointer Insulin secretion rates correlated with rates of anaplerosis and TCA cycle. Black-Right-Pointing-Pointer Mitochondria metabolism and substrate cycles augment secretion signal of ATP. -- Abstract: Mechanistic models of glucose stimulated insulin secretion (GSIS) established in minimal media in vitro, may not accurately describe the complexity of coupling metabolism with insulin secretion that occurs in vivo. As a first approximation, we have evaluated metabolic pathways in a typical growth media, DMEM as a surrogate in vivo medium, for comparison to metabolic fluxes observed under the typical experimental conditions using the simple salt-buffer of KRB. Changes in metabolism in response to glucose and amino acids and coupling to insulin secretion were measured in INS-1 832/13 cells. Media effects on mitochondrial function and the coupling efficiency of oxidative phosphorylation were determined by fluorometrically measured oxygen consumption rates (OCRs) combined with {sup 31}P NMR measured rates of ATP synthesis. Substrate preferences and pathways into the TCA cycle, and the synthesis of mitochondrial 2nd messengers by anaplerosis were determined by {sup 13}C NMR isotopomer analysis of the fate of [U-{sup 13}C] glucose metabolism. Despite similar incremental increases in insulin secretion, the changes of OCR in response to increasing glucose from 2.5 to 15 mM were blunted in DMEM relative to KRB. Basal and stimulated rates of insulin secretion rates were consistently higher in DMEM, while ATP synthesis rates were identical in both DMEM and KRB, suggesting greater mitochondrial uncoupling in DMEM. The relative rates of anaplerosis, and hence synthesis and export of 2nd messengers from the mitochondria were found

  3. M19 modulates skeletal muscle differentiation and insulin secretion in pancreatic β-cells through modulation of respiratory chain activity.

    Directory of Open Access Journals (Sweden)

    Linda Cambier

    Full Text Available Mitochondrial dysfunction due to nuclear or mitochondrial DNA alterations contributes to multiple diseases such as metabolic myopathies, neurodegenerative disorders, diabetes and cancer. Nevertheless, to date, only half of the estimated 1,500 mitochondrial proteins has been identified, and the function of most of these proteins remains to be determined. Here, we characterize the function of M19, a novel mitochondrial nucleoid protein, in muscle and pancreatic β-cells. We have identified a 13-long amino acid sequence located at the N-terminus of M19 that targets the protein to mitochondria. Furthermore, using RNA interference and over-expression strategies, we demonstrate that M19 modulates mitochondrial oxygen consumption and ATP production, and could therefore regulate the respiratory chain activity. In an effort to determine whether M19 could play a role in the regulation of various cell activities, we show that this nucleoid protein, probably through its modulation of mitochondrial ATP production, acts on late muscle differentiation in myogenic C2C12 cells, and plays a permissive role on insulin secretion under basal glucose conditions in INS-1 pancreatic β-cells. Our results are therefore establishing a functional link between a mitochondrial nucleoid protein and the modulation of respiratory chain activities leading to the regulation of major cellular processes such as myogenesis and insulin secretion.

  4. Alkali pH directly activates ATP-sensitive K+ channels and inhibits insulin secretion in beta-cells.

    Science.gov (United States)

    Manning Fox, Jocelyn E; Karaman, Gunce; Wheeler, Michael B

    2006-11-17

    Glucose stimulation of pancreatic beta-cells is reported to lead to sustained alkalization, while extracellular application of weak bases is reported to inhibit electrical activity and decrease insulin secretion. We hypothesize that beta-cell K(ATP) channel activity is modulated by alkaline pH. Using the excised patch-clamp technique, we demonstrate a direct stimulatory action of alkali pH on recombinant SUR1/Kir6.2 channels due to increased open probability. Bath application of alkali pH similarly activates native islet beta-cell K(ATP) channels, leading to an inhibition of action potentials, and hyperpolarization of membrane potential. In situ pancreatic perfusion confirms that these cellular effects of alkali pH are observable at a functional level, resulting in decreases in both phase 1 and phase 2 glucose-stimulated insulin secretion. Our data are the first to report a stimulatory effect of a range of alkali pH on K(ATP) channel activity and link this to downstream effects on islet beta-cell function.

  5. Suppression of the Nuclear Factor Eny2 Increases Insulin Secretion in Poorly Functioning INS-1E Insulinoma Cells

    Directory of Open Access Journals (Sweden)

    P. Dames

    2012-01-01

    Full Text Available Eny2, the mammalian ortholog of yeast Sus1 and drosophila E(y2, is a nuclear factor that participates in several steps of gene transcription and in mRNA export. We had previously found that Eny2 expression changes in mouse pancreatic islets during the metabolic adaptation to pregnancy. We therefore hypothesized that the protein contributes to the regulation of islet endocrine cell function and tested this hypothesis in rat INS-1E insulinoma cells. Overexpression of Eny2 had no effect but siRNA-mediated knockdown of Eny2 resulted in markedly increased glucose and exendin-4-induced insulin secretion from otherwise poorly glucose-responsive INS-1E cells. Insulin content, cellular viability, and the expression levels of several key components of glucose sensing remained unchanged; however glucose-dependent cellular metabolism was higher after Eny2 knockdown. Suppression of Eny2 enhanced the intracellular incretin signal downstream of cAMP. The use of specific cAMP analogues and pathway inhibitors primarily implicated the PKA and to a lesser extent the EPAC pathway. In summary, we identified a potential link between the nuclear protein Eny2 and insulin secretion. Suppression of Eny2 resulted in increased glucose and incretin-induced insulin release from a poorly glucose-responsive INS-1E subline. Whether these findings extend to other experimental conditions or to in vivo physiology needs to be determined in further studies.

  6. Rates of insulin secretion in INS-1 cells are enhanced by coupling to anaplerosis and Kreb's cycle flux independent of ATP synthesis.

    Science.gov (United States)

    Cline, Gary W; Pongratz, Rebecca L; Zhao, Xiaojian; Papas, Klearchos K

    2011-11-11

    Mechanistic models of glucose stimulated insulin secretion (GSIS) established in minimal media in vitro, may not accurately describe the complexity of coupling metabolism with insulin secretion that occurs in vivo. As a first approximation, we have evaluated metabolic pathways in a typical growth media, DMEM as a surrogate in vivo medium, for comparison to metabolic fluxes observed under the typical experimental conditions using the simple salt-buffer of KRB. Changes in metabolism in response to glucose and amino acids and coupling to insulin secretion were measured in INS-1 832/13 cells. Media effects on mitochondrial function and the coupling efficiency of oxidative phosphorylation were determined by fluorometrically measured oxygen consumption rates (OCRs) combined with (31)P NMR measured rates of ATP synthesis. Substrate preferences and pathways into the TCA cycle, and the synthesis of mitochondrial 2nd messengers by anaplerosis were determined by (13)C NMR isotopomer analysis of the fate of [U-(13)C] glucose metabolism. Despite similar incremental increases in insulin secretion, the changes of OCR in response to increasing glucose from 2.5 to 15mM were blunted in DMEM relative to KRB. Basal and stimulated rates of insulin secretion rates were consistently higher in DMEM, while ATP synthesis rates were identical in both DMEM and KRB, suggesting greater mitochondrial uncoupling in DMEM. The relative rates of anaplerosis, and hence synthesis and export of 2nd messengers from the mitochondria were found to be similar in DMEM to those in KRB. And, the correlation of total PC flux with insulin secretion rates in DMEM was found to be congruous with the correlation in KRB. Together, these results suggest that signaling mechanisms associated with both TCA cycle flux and with anaplerotic flux, but not ATP production, may be responsible for the enhanced rates of insulin secretion in more complex, and physiologically-relevant media. Copyright © 2011 Elsevier Inc. All

  7. Glucose-Dependent Insulin Secretion in Pancreatic β-Cell Islets from Male Rats Requires Ca2+ Release via ROS-Stimulated Ryanodine Receptors.

    Directory of Open Access Journals (Sweden)

    Paola Llanos

    Full Text Available Glucose-stimulated insulin secretion (GSIS from pancreatic β-cells requires an increase in intracellular free Ca2+ concentration ([Ca2+]. Glucose uptake into β-cells promotes Ca2+ influx and reactive oxygen species (ROS generation. In other cell types, Ca2+ and ROS jointly induce Ca2+ release mediated by ryanodine receptor (RyR channels. Therefore, we explored here if RyR-mediated Ca2+ release contributes to GSIS in β-cell islets isolated from male rats. Stimulatory glucose increased islet insulin secretion, and promoted ROS generation in islets and dissociated β-cells. Conventional PCR assays and immunostaining confirmed that β-cells express RyR2, the cardiac RyR isoform. Extended incubation of β-cell islets with inhibitory ryanodine suppressed GSIS; so did the antioxidant N-acetyl cysteine (NAC, which also decreased insulin secretion induced by glucose plus caffeine. Inhibitory ryanodine or NAC did not affect insulin secretion induced by glucose plus carbachol, which engages inositol 1,4,5-trisphosphate receptors. Incubation of islets with H2O2 in basal glucose increased insulin secretion 2-fold. Inhibitory ryanodine significantly decreased H2O2-stimulated insulin secretion and prevented the 4.5-fold increase of cytoplasmic [Ca2+] produced by incubation of dissociated β-cells with H2O2. Addition of stimulatory glucose or H2O2 (in basal glucose to β-cells disaggregated from islets increased RyR2 S-glutathionylation to similar levels, measured by a proximity ligation assay; in contrast, NAC significantly reduced the RyR2 S-glutathionylation increase produced by stimulatory glucose. We propose that RyR2-mediated Ca2+ release, induced by the concomitant increases in [Ca2+] and ROS produced by stimulatory glucose, is an essential step in GSIS.

  8. Phenolic Compounds from Fermented Berry Beverages Modulated Gene and Protein Expression To Increase Insulin Secretion from Pancreatic β-Cells in Vitro.

    Science.gov (United States)

    Johnson, Michelle H; de Mejia, Elvira Gonzalez

    2016-03-30

    Berries are a rich source of bioactive phenolic compounds that are able to bind and inhibit the enzyme dipeptidyl peptidase-IV (DPP-IV), a current target for type-2 diabetes therapy. The objectives were to determine the role of berry phenolic compounds to modulate incretin-cleaving DPP-IV and its substrate glucagon-like peptide-1 (GLP-1), insulin secretion from pancreatic β-cells, and genes and proteins involved in the insulin secretion pathway using cell culture. Anthocyanins (ANC) from 50% blueberry-50% blackberry (Blu-Bla) and 100% blackberry (Bla) fermented beverages at 50 μM cyanidin-3-glucoside equivalents increased (p beverages have the potential to modulate DPP-IV and its substrate GLP-1, to increase insulin secretion, and to upregulate expression of mRNA of insulin-receptor associated genes and proteins in pancreatic β-cells.

  9. A New Method for Generating Insulin-Secreting Cells from Human Pancreatic Epithelial Cells After Islet Isolation Transformed by NeuroD1

    Science.gov (United States)

    Shimoda, Masayuki; Chen, Shuyuan; Noguchi, Hirofumi; Takita, Morihito; Sugimoto, Koji; Itoh, Takeshi; Chujo, Daisuke; Iwahashi, Shuichi; Naziruddin, Bashoo; Levy, Marlon F.

    2014-01-01

    Abstract The generation of insulin-secreting cells from nonendocrine pancreatic epithelial cells (NEPEC) has been demonstrated for potential clinical use in the treatment of diabetes. However, previous methods either had limited efficacy or required viral vectors, which hinder clinical application. In this study, we aimed to establish an efficient method of insulin-secreting cell generation from NEPEC without viral vectors. We used nonislet fractions from both research-grade human pancreata from brain-dead donors and clinical pancreata after total pancreatectomy with autologous islet transplantation to treat chronic pancreatitis. It is of note that a few islets could be mingled in the nonislet fractions, but their influence could be limited. The NeuroD1 gene was induced into NEPEC using an effective triple lipofection method without viral vectors to generate insulin-secreting cells. The differentiation was promoted by adding a growth factor cocktail into the culture medium. Using the research-grade human pancreata, the effective method showed high efficacy in the differentiation of NEPEC into insulin-positive cells that secreted insulin in response to a glucose challenge and improved diabetes after being transplanted into diabetic athymic mice. Using the clinical pancreata, similar efficacy was obtained, even though those pancreata suffered chronic pancreatitis. In conclusion, our effective differentiation protocol with triple lipofection method enabled us to achieve very efficient insulin-secreting cell generation from human NEPEC without viral vectors. This method offers the potential for supplemental insulin-secreting cell transplantation for both allogeneic and autologous islet transplantation. PMID:24845703

  10. Calcium has a permissive role in interleukin-1beta-induced c-jun N-terminal kinase activation in insulin-secreting cells

    DEFF Research Database (Denmark)

    Størling, Joachim; Zaitsev, Sergei V; Kapelioukh, Iouri L

    2005-01-01

    The c-jun N-terminal kinase (JNK) signaling pathway mediates IL-1beta-induced apoptosis in insulin-secreting cells, a mechanism relevant to the destruction of pancreatic beta-cells in type 1 and 2 diabetes. However, the mechanisms that contribute to IL-1beta activation of JNK in beta-cells are la...

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

    Directory of Open Access Journals (Sweden)

    Ya-Li Zheng

    Full Text Available 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.

  12. The comprehensive electrophysiological study of curcuminoids on delayed-rectifier K+ currents in insulin-secreting cells.

    Science.gov (United States)

    Kuo, Ping-Chung; Yang, Chia-Jung; Lee, Yu-Chi; Chen, Pei-Chun; Liu, Yen-Chin; Wu, Sheng-Nan

    2018-01-15

    Curcumin (CUR) has been demonstrated to induce insulin release from pancreatic β-cells; however, how curcuminoids (including demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC)) exert any possible effects on membrane ion currents inherently in insulin-secreting cells remains largely unclear. The effects of CUR and other structurally similar curcuminoids on ion currents in rat insulin-secreting (INS-1) insulinoma cells were therefore investigated in this study. The effects of these compounds on ionic currents and membrane potential were studied by patch-clamp technique. CUR suppressed the amplitude of delayed-rectifier K + current (I K(DR) ) in a time-, state- and concentration-dependent manner in these cells and the inhibition was not reversed by diazoxide, nicorandil or chlorotoxin. The value of dissociation constant for CUR-induced suppression of I K(DR) in INS-1 cells was 1.26μM. Despite the inability of CUR to alter the activation rate of I K(DR) , it accelerated current inactivation elicited by membrane depolarization. Increasing CUR concentrations shifted the inactivation curve of I K(DR) to hyperpolarized potential and slowed the recovery of I K(DR) inactivation. CUR, DMC, and BDMC all exerted depressant actions on I K(DR) amplitude to a similar magnitude, although DMC and BDMC did not increase current inactivation clearly. CUR slightly suppressed the peak amplitude of voltage-gated Na + current. CUR, DMC and BDMC depolarized the resting potential and increased firing frequency of action potentials. The CUR-mediated decrease of I K(DR) and the increase of current inactivation also occurred in βTC-6 INS-1 cells. Taken these results together, these effects may be one of the possible mechanisms contributing their insulin-releasing effect. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Development of the insulin secretion mechanism in fetal and neonatal rat pancreatic B-cells: response to glucose, K+, theophylline, and carbamylcholine

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    A.C. Mendonça

    1998-06-01

    Full Text Available We studied the development of the insulin secretion mechanism in the pancreas of fetal (19- and 21-day-old, neonatal (3-day-old, and adult (90-day-old rats in response to stimulation with 8.3 or 16.7 mM glucose, 30 mM K+, 5 mM theophylline (Theo and 200 µM carbamylcholine (Cch. No effect of glucose or high K+ was observed on the pancreas from 19-day-old fetuses, whereas Theo and Cch significantly increased insulin secretion at this age (82 and 127% above basal levels, respectively. High K+ also failed to alter the insulin secretion in the pancreas from 21-day-old fetuses, whereas 8.3 mM and 16.7 mM glucose significantly stimulated insulin release by 41 and 54% above basal levels, respectively. Similar results were obtained with Theo and Cch. A more marked effect of glucose on insulin secretion was observed in the pancreas of 3-day-old rats, reaching 84 and 179% above basal levels with 8.3 mM and 16.7 mM glucose, respectively. At this age, both Theo and Cch increased insulin secretion to close to two-times basal levels. In islets from adult rats, 8.3 mM and 16.7 mM glucose, Theo, and Cch increased the insulin release by 104, 193, 318 and 396% above basal levels, respectively. These data indicate that pancreatic B-cells from 19-day-old fetuses were already sensitive to stimuli that use either cAMP or IP3 and DAG as second messengers, but insensitive to stimuli such as glucose and high K+ that induce membrane depolarization. The greater effect of glucose on insulin secretion during the neonatal period indicates that this period is crucial for the maturation of the glucose-sensing mechanism in B-cells.

  14. Mitochondrial Dysfunction Contributes to Impaired Insulin Secretion in INS-1 Cells with Dominant-negative Mutations of HNF-1α and in HNF-1α-deficient Islets*

    Science.gov (United States)

    Pongratz, Rebecca L.; Kibbey, Richard G.; Kirkpatrick, Clare L.; Zhao, Xiaojian; Pontoglio, Marco; Yaniv, Moshe; Wollheim, Claes B.; Shulman, Gerald I.; Cline, Gary W.

    2009-01-01

    Maturity Onset Diabetes of the Young-type 3 (MODY-3) has been linked to mutations in the transcription factor hepatic nuclear factor (HNF)-1α, resulting in deficiency in glucose-stimulated insulin secretion. In INS-1 cells overexpressing doxycycline-inducible HNF-1α dominant-negative (DN-) gene mutations, and islets from Hnf-1α knock-out mice, insulin secretion was impaired in response to glucose (15 mm) and other nutrient secretagogues. Decreased rates of insulin secretion in response to glutamine plus leucine and to methyl pyruvate, but not potassium depolarization, indicate defects specific to mitochondrial metabolism. To identify the biochemical mechanisms responsible for impaired insulin secretion, we used 31P NMR measured mitochondrial ATP synthesis (distinct from glycolytic ATP synthesis) together with oxygen consumption measurements to determine the efficiency of mitochondrial oxidative phosphorylation. Mitochondrial uncoupling was significantly higher in DN-HNF-1α cells, such that rates of ATP synthesis were decreased by approximately one-half in response to the secretagogues glucose, glutamine plus leucine, or pyruvate. In addition to closure of the ATP-sensitive K+ channels with mitochondrial ATP synthesis, mitochondrial production of second messengers through increased anaplerotic flux has been shown to be critical for coupling metabolism to insulin secretion. 13C-Isotopomer analysis and tandem mass spectrometry measurement of Krebs cycle intermediates revealed a negative impact of DN-HNF-1α and Hnf-1α knock-out on mitochondrial second messenger production with glucose but not amino acids. Taken together, these results indicate that, in addition to reduced glycolytic flux, uncoupling of mitochondrial oxidative phosphorylation contributes to impaired nutrient-stimulated insulin secretion with either mutations or loss of HNF-1α. PMID:19376774

  15. Bone morphogenetic protein 4 inhibits insulin secretion from rodent beta cells through regulation of calbindin1 expression and reduced voltage-dependent calcium currents

    DEFF Research Database (Denmark)

    Christensen, Gitte L.; Jacobsen, Maria L. B.; Wendt, Anna

    2015-01-01

    AIMS/HYPOTHESIS: Type 2 diabetes is characterised by progressive loss of pancreatic beta cell mass and function. Therefore, it is of therapeutic interest to identify factors with the potential to improve beta cell proliferation and insulin secretion. Bone morphogenetic protein 4 (BMP4) expression...

  16. Enterovirus infection of human islets of Langerhans affects β-cell function resulting in disintegrated islets, decreased glucose stimulated insulin secretion and loss of Golgi structure

    NARCIS (Netherlands)

    Hodik, M; Skog, O; Lukinius, A; Isaza-Correa, J M; Kuipers, Jeroen; Giepmans, B N G; Frisk, G

    AIMS/HYPOTHESIS: In type 1 diabetes (T1D), most insulin-producing β cells are destroyed, but the trigger is unknown. One of the possible triggers is a virus infection and the aim of this study was to test if enterovirus infection affects glucose stimulated insulin secretion and the effect of virus

  17. The level of menadione redox-cycling in pancreatic β-cells is proportional to the glucose concentration: role of NADH and consequences for insulin secretion.

    Science.gov (United States)

    Heart, Emma; Palo, Meridith; Womack, Trayce; Smith, Peter J S; Gray, Joshua P

    2012-01-15

    Pancreatic β-cells release insulin in response to elevation of glucose from basal (4-7mM) to stimulatory (8-16mM) levels. Metabolism of glucose by the β-cell results in the production of low levels of reactive oxygen intermediates (ROI), such as hydrogen peroxide (H(2)O(2)), a newly recognized coupling factor linking glucose metabolism to insulin secretion. However, high and toxic levels of H(2)O(2) inhibit insulin secretion. Menadione, which produces H(2)O(2) via redox cycling mechanism in a dose-dependent manner, was investigated for its effect on β-cell metabolism and insulin secretion in INS-1 832/13, a rat β-cell insulinoma cell line, and primary rodent islets. Menadione-dependent redox cycling and resulting H(2)O(2) production under stimulatory glucose exceeded several-fold those reached at basal glucose. This was paralleled by a differential effect of menadione (0.1-10μM) on insulin secretion, which was enhanced at basal, but inhibited at stimulatory glucose. Redox cycling of menadione and H(2)O(2) formation was dependent on glycolytically-derived NADH, as inhibition of glycolysis and application of non-glycogenic insulin secretagogues did not support redox cycling. In addition, activity of plasma membrane electron transport, a system dependent in part on glycolytically-derived NADH, was also inhibited by menadione. Menadione-dependent redox cycling was sensitive to the NQO1 inhibitor dicoumarol and the flavoprotein inhibitor diphenylene iodonium, suggesting a role for NQO1 and other oxidoreductases in this process. These data may explain the apparent dichotomy between the stimulatory and inhibitory effects of H(2)O(2) and menadione on insulin secretion. Published by Elsevier Inc.

  18. Mechanisms of estradiol-induced insulin secretion by the G protein-coupled estrogen receptor GPR30/GPER in pancreatic beta-cells.

    Science.gov (United States)

    Sharma, Geetanjali; Prossnitz, Eric R

    2011-08-01

    Sexual dimorphism and supplementation studies suggest an important role for estrogens in the amelioration of glucose intolerance and diabetes. Because little is known regarding the signaling mechanisms involved in estradiol-mediated insulin secretion, we investigated the role of the G protein-coupled receptor 30, now designated G protein-coupled estrogen receptor (GPER), in activating signal transduction cascades in β-cells, leading to secretion of insulin. GPER function in estradiol-induced signaling in the pancreatic β-cell line MIN6 was assessed using small interfering RNA and GPER-selective ligands (G-1 and G15) and in islets isolated from wild-type and GPER knockout mice. GPER is expressed in MIN6 cells, where estradiol and the GPER-selective agonist G-1 mediate calcium mobilization and activation of ERK and phosphatidylinositol 3-kinase. Both estradiol and G-1 induced insulin secretion under low- and high-glucose conditions, which was inhibited by pretreatment with GPER antagonist G15 as well as depletion of GPER by small interfering RNA. Insulin secretion in response to estradiol and G-1 was dependent on epidermal growth factor receptor and ERK activation and further modulated by phosphatidylinositol 3-kinase activity. In islets isolated from wild-type mice, the GPER antagonist G15 inhibited insulin secretion induced by estradiol and G-1, both of which failed to induce insulin secretion in islets obtained from GPER knockout mice. Our results indicate that GPER activation of the epidermal growth factor receptor and ERK in response to estradiol treatment plays a critical role in the secretion of insulin from β-cells. The results of this study suggest that the activation of downstream signaling pathways by the GPER-selective ligand G-1 could represent a novel therapeutic strategy in the treatment of diabetes.

  19. Mechanisms of Estradiol-Induced Insulin Secretion by the G Protein-Coupled Estrogen Receptor GPR30/GPER in Pancreatic β-Cells

    Science.gov (United States)

    Sharma, Geetanjali

    2011-01-01

    Sexual dimorphism and supplementation studies suggest an important role for estrogens in the amelioration of glucose intolerance and diabetes. Because little is known regarding the signaling mechanisms involved in estradiol-mediated insulin secretion, we investigated the role of the G protein-coupled receptor 30, now designated G protein-coupled estrogen receptor (GPER), in activating signal transduction cascades in β-cells, leading to secretion of insulin. GPER function in estradiol-induced signaling in the pancreatic β-cell line MIN6 was assessed using small interfering RNA and GPER-selective ligands (G-1 and G15) and in islets isolated from wild-type and GPER knockout mice. GPER is expressed in MIN6 cells, where estradiol and the GPER-selective agonist G-1 mediate calcium mobilization and activation of ERK and phosphatidylinositol 3-kinase. Both estradiol and G-1 induced insulin secretion under low- and high-glucose conditions, which was inhibited by pretreatment with GPER antagonist G15 as well as depletion of GPER by small interfering RNA. Insulin secretion in response to estradiol and G-1 was dependent on epidermal growth factor receptor and ERK activation and further modulated by phosphatidylinositol 3-kinase activity. In islets isolated from wild-type mice, the GPER antagonist G15 inhibited insulin secretion induced by estradiol and G-1, both of which failed to induce insulin secretion in islets obtained from GPER knockout mice. Our results indicate that GPER activation of the epidermal growth factor receptor and ERK in response to estradiol treatment plays a critical role in the secretion of insulin from β-cells. The results of this study suggest that the activation of downstream signaling pathways by the GPER-selective ligand G-1 could represent a novel therapeutic strategy in the treatment of diabetes. PMID:21673097

  20. Expansion and conversion of human pancreatic ductal cells into insulin-secreting endocrine cells.

    Science.gov (United States)

    Lee, Jonghyeob; Sugiyama, Takuya; Liu, Yinghua; Wang, Jing; Gu, Xueying; Lei, Ji; Markmann, James F; Miyazaki, Satsuki; Miyazaki, Jun-Ichi; Szot, Gregory L; Bottino, Rita; Kim, Seung K

    2013-11-19

    Pancreatic islet β-cell insufficiency underlies pathogenesis of diabetes mellitus; thus, functional β-cell replacement from renewable sources is the focus of intensive worldwide effort. However, in vitro production of progeny that secrete insulin in response to physiological cues from primary human cells has proven elusive. Here we describe fractionation, expansion and conversion of primary adult human pancreatic ductal cells into progeny resembling native β-cells. FACS-sorted adult human ductal cells clonally expanded as spheres in culture, while retaining ductal characteristics. Expression of the cardinal islet developmental regulators Neurog3, MafA, Pdx1 and Pax6 converted exocrine duct cells into endocrine progeny with hallmark β-cell properties, including the ability to synthesize, process and store insulin, and secrete it in response to glucose or other depolarizing stimuli. These studies provide evidence that genetic reprogramming of expandable human pancreatic cells with defined factors may serve as a general strategy for islet replacement in diabetes. DOI: http://dx.doi.org/10.7554/eLife.00940.001.

  1. Rising Intracellular Zinc by Membrane Depolarization and Glucose in Insulin-Secreting Clonal HIT-T15 Beta Cells

    Directory of Open Access Journals (Sweden)

    Kira G. Slepchenko

    2012-01-01

    Full Text Available Zinc (Zn2+ appears to be intimately involved in insulin metabolism since insulin secretion is correlated with zinc secretion in response to glucose stimulation, but little is known about the regulation of zinc homeostasis in pancreatic beta-cells. This study set out to identify the intracellular zinc transient by imaging free cytosolic zinc in HIT-T15 beta-cells with fluorescent zinc indicators. We observed that membrane depolarization by KCl (30–60 mM was able to induce a rapid increase in cytosolic concentration of zinc. Multiple zinc transients of similar magnitude were elicited during repeated stimulations. The amplitude of zinc responses was not affected by the removal of extracellular calcium or zinc. However, the half-time of the rising slope was significantly slower after removing extracellular zinc with zinc chelator CaEDTA, suggesting that extracellular zinc affect the initial rising phase of zinc response. Glucose (10 mM induced substantial and progressive increases in intracellular zinc concentration in a similar way as KCl, with variation in the onset and the duration of zinc mobilization. It is known that the depolarization of beta-cell membrane is coupled with the secretion of insulin. Rising intracellular zinc concentration may act as a critical signaling factor in insulin metabolism of pancreatic beta-cells.

  2. Rising intracellular zinc by membrane depolarization and glucose in insulin-secreting clonal HIT-T15 beta cells.

    Science.gov (United States)

    Slepchenko, Kira G; Li, Yang V

    2012-01-01

    Zinc (Zn(2+)) appears to be intimately involved in insulin metabolism since insulin secretion is correlated with zinc secretion in response to glucose stimulation, but little is known about the regulation of zinc homeostasis in pancreatic beta-cells. This study set out to identify the intracellular zinc transient by imaging free cytosolic zinc in HIT-T15 beta-cells with fluorescent zinc indicators. We observed that membrane depolarization by KCl (30-60 mM) was able to induce a rapid increase in cytosolic concentration of zinc. Multiple zinc transients of similar magnitude were elicited during repeated stimulations. The amplitude of zinc responses was not affected by the removal of extracellular calcium or zinc. However, the half-time of the rising slope was significantly slower after removing extracellular zinc with zinc chelator CaEDTA, suggesting that extracellular zinc affect the initial rising phase of zinc response. Glucose (10 mM) induced substantial and progressive increases in intracellular zinc concentration in a similar way as KCl, with variation in the onset and the duration of zinc mobilization. It is known that the depolarization of beta-cell membrane is coupled with the secretion of insulin. Rising intracellular zinc concentration may act as a critical signaling factor in insulin metabolism of pancreatic beta-cells.

  3. The level of menadione redox-cycling in pancreatic β-cells is proportional to the glucose concentration: Role of NADH and consequences for insulin secretion

    Energy Technology Data Exchange (ETDEWEB)

    Heart, Emma [Cellular Dynamics Program, Marine Biological Laboratory, Woods Hole, MA, 02543 (United States); Palo, Meridith; Womack, Trayce [Department of Science, United States Coast Guard Academy, New London, CT, 06320 (United States); Smith, Peter J.S. [Cellular Dynamics Program, Marine Biological Laboratory, Woods Hole, MA, 02543 (United States); Institute for Life Sciences, University of Southampton (United Kingdom); Gray, Joshua P., E-mail: Joshua.p.gray@uscga.edu [Cellular Dynamics Program, Marine Biological Laboratory, Woods Hole, MA, 02543 (United States); Department of Science, United States Coast Guard Academy, New London, CT, 06320 (United States)

    2012-01-15

    Pancreatic β-cells release insulin in response to elevation of glucose from basal (4–7 mM) to stimulatory (8–16 mM) levels. Metabolism of glucose by the β-cell results in the production of low levels of reactive oxygen intermediates (ROI), such as hydrogen peroxide (H{sub 2}O{sub 2}), a newly recognized coupling factor linking glucose metabolism to insulin secretion. However, high and toxic levels of H{sub 2}O{sub 2} inhibit insulin secretion. Menadione, which produces H{sub 2}O{sub 2} via redox cycling mechanism in a dose-dependent manner, was investigated for its effect on β-cell metabolism and insulin secretion in INS-1 832/13, a rat β-cell insulinoma cell line, and primary rodent islets. Menadione-dependent redox cycling and resulting H{sub 2}O{sub 2} production under stimulatory glucose exceeded several-fold those reached at basal glucose. This was paralleled by a differential effect of menadione (0.1–10 μM) on insulin secretion, which was enhanced at basal, but inhibited at stimulatory glucose. Redox cycling of menadione and H{sub 2}O{sub 2} formation was dependent on glycolytically-derived NADH, as inhibition of glycolysis and application of non-glycogenic insulin secretagogues did not support redox cycling. In addition, activity of plasma membrane electron transport, a system dependent in part on glycolytically-derived NADH, was also inhibited by menadione. Menadione-dependent redox cycling was sensitive to the NQO1 inhibitor dicoumarol and the flavoprotein inhibitor diphenylene iodonium, suggesting a role for NQO1 and other oxidoreductases in this process. These data may explain the apparent dichotomy between the stimulatory and inhibitory effects of H{sub 2}O{sub 2} and menadione on insulin secretion. -- Highlights: ► Menadione stimulation or inhibition of insulin secretion is dependent upon applied glucose levels. ► Menadione-dependent H{sub 2}O{sub 2} production is proportional to applied glucose levels. ► Quinone-mediated redox cycling

  4. The level of menadione redox-cycling in pancreatic β-cells is proportional to the glucose concentration: Role of NADH and consequences for insulin secretion

    International Nuclear Information System (INIS)

    Heart, Emma; Palo, Meridith; Womack, Trayce; Smith, Peter J.S.; Gray, Joshua P.

    2012-01-01

    Pancreatic β-cells release insulin in response to elevation of glucose from basal (4–7 mM) to stimulatory (8–16 mM) levels. Metabolism of glucose by the β-cell results in the production of low levels of reactive oxygen intermediates (ROI), such as hydrogen peroxide (H 2 O 2 ), a newly recognized coupling factor linking glucose metabolism to insulin secretion. However, high and toxic levels of H 2 O 2 inhibit insulin secretion. Menadione, which produces H 2 O 2 via redox cycling mechanism in a dose-dependent manner, was investigated for its effect on β-cell metabolism and insulin secretion in INS-1 832/13, a rat β-cell insulinoma cell line, and primary rodent islets. Menadione-dependent redox cycling and resulting H 2 O 2 production under stimulatory glucose exceeded several-fold those reached at basal glucose. This was paralleled by a differential effect of menadione (0.1–10 μM) on insulin secretion, which was enhanced at basal, but inhibited at stimulatory glucose. Redox cycling of menadione and H 2 O 2 formation was dependent on glycolytically-derived NADH, as inhibition of glycolysis and application of non-glycogenic insulin secretagogues did not support redox cycling. In addition, activity of plasma membrane electron transport, a system dependent in part on glycolytically-derived NADH, was also inhibited by menadione. Menadione-dependent redox cycling was sensitive to the NQO1 inhibitor dicoumarol and the flavoprotein inhibitor diphenylene iodonium, suggesting a role for NQO1 and other oxidoreductases in this process. These data may explain the apparent dichotomy between the stimulatory and inhibitory effects of H 2 O 2 and menadione on insulin secretion. -- Highlights: ► Menadione stimulation or inhibition of insulin secretion is dependent upon applied glucose levels. ► Menadione-dependent H 2 O 2 production is proportional to applied glucose levels. ► Quinone-mediated redox cycling is dependent on glycolysis

  5. Corydalis edulis Maxim. Promotes Insulin Secretion via the Activation of Protein Kinase Cs (PKCs) in Mice and Pancreatic β Cells.

    Science.gov (United States)

    Zheng, Jiao; Zhao, Yunfang; Lun, Qixing; Song, Yuelin; Shi, Shepo; Gu, Xiaopan; Pan, Bo; Qu, Changhai; Li, Jun; Tu, Pengfei

    2017-01-16

    Corydalis edulis Maxim., a widely grown plant in China, had been proposed for the treatment for type 2 diabetes mellitus. In this study, we found that C. edulis extract (CE) is protective against diabetes in mice. The treatment of hyperglycemic and hyperlipidemic apolipoprotein E (ApoE)-/- mice with a high dose of CE reduced serum glucose by 28.84% and serum total cholesterol by 17.34% and increased insulin release. We also found that CE significantly enhanced insulin secretion in a glucose-independent manner in hamster pancreatic β cell (HIT-T15). Further investigation revealed that CE stimulated insulin exocytosis by a protein kinase C (PKC)-dependent signaling pathway and that CE selectively activated novel protein kinase Cs (nPKCs) and atypical PKCs (aPKCs) but not conventional PKCs (cPKCs) in HIT-T15 cells. To the best of our knowledge, our study is the first to identify the PKC pathway as a direct target and one of the major mechanisms underlying the antidiabetic effect of CE. Given the good insulinotropic effect of this herbal medicine, CE is a promising agent for the development of new drugs for treating diabetes.

  6. Methylglyoxal Impairs Insulin Secretion of Pancreatic β-Cells through Increased Production of ROS and Mitochondrial Dysfunction Mediated by Upregulation of UCP2 and MAPKs

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    Jinshuang Bo

    2016-01-01

    Full Text Available Methylglyoxal (MG is a highly reactive glucose metabolic intermediate and a major precursor of advanced glycation end products. MG level is elevated in hyperglycemic disorders such as diabetes mellitus. Substantial evidence has shown that MG is involved in the pathogenesis of diabetes and diabetic complications. We investigated the impact of MG on insulin secretion by MIN6 and INS-1 cells and the potential mechanisms of this effect. Our study demonstrates that MG impaired insulin secretion by MIN6 or ISN-1 cells in a dose-dependent manner. It increased reactive oxygen species (ROS production and apoptosis rate in MIN6 or ISN-1 cells and inhibited mitochondrial membrane potential (MMP and ATP production. Furthermore, the expression of UCP2, JNK, and P38 as well as the phosphorylation JNK and P38 was increased by MG. These effects of MG were attenuated by MG scavenger N-acetyl cysteine. Collectively, these data indicate that MG impairs insulin secretion of pancreatic β-cells through increasing ROS production. High levels of ROS can damage β-cells directly via JNK/P38 upregulation and through activation of UCP2 resulting in reduced MMP and ATP production, leading to β-cell dysfunction and impairment of insulin production.

  7. Developmental programming of polycystic ovary syndrome (PCOS): prenatal androgens establish pancreatic islet α/β cell ratio and subsequent insulin secretion.

    Science.gov (United States)

    Ramaswamy, S; Grace, C; Mattei, A A; Siemienowicz, K; Brownlee, W; MacCallum, J; McNeilly, A S; Duncan, W C; Rae, M T

    2016-06-06

    Exogenous androgenic steroids applied to pregnant sheep programmes a PCOS-like phenotype in female offspring. Via ultrasound guidance we applied steroids directly to ovine fetuses at d62 and d82 of gestation, and examined fetal (day 90 gestation) and postnatal (11 months old) pancreatic structure and function. Of three classes of steroid agonists applied (androgen - Testosterone propionate (TP), estrogen - Diethystilbesterol (DES) and glucocorticoid - Dexamethasone (DEX)), only androgens (TP) caused altered pancreatic development. Beta cell numbers were significantly elevated in prenatally androgenised female fetuses (P = 0.03) (to approximately the higher numbers found in male fetuses), whereas alpha cell counts were unaffected, precipitating decreased alpha:beta cell ratios in the developing fetal pancreas (P = 0.001), sustained into adolescence (P = 0.0004). In adolescence basal insulin secretion was significantly higher in female offspring from androgen-excess pregnancies (P = 0.045), and an exaggerated, hyperinsulinaemic response to glucose challenge (P = 0.0007) observed, whereas prenatal DES or DEX treatment had no effects upon insulin secretion. Postnatal insulin secretion correlated with beta cell numbers (P = 0.03). We conclude that the pancreas is a primary locus of androgenic stimulation during development, giving rise to postnatal offspring whose pancreas secreted excess insulin due to excess beta cells in the presence of a normal number of alpha cells.

  8. Arsenite reduces insulin secretion in rat pancreatic β-cells by decreasing the calcium-dependent calpain-10 proteolysis of SNAP-25

    International Nuclear Information System (INIS)

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

    2008-01-01

    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 β-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 2+ ]i oscillations needed for glucose-stimulated insulin secretion were abated in the presence of subchronic low arsenite doses (0.5-2 μM). The global activity of calpains increased with 2 μM arsenite. However, during the secretion of insulin stimulated with glucose (15.6 mM), 1 μM 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 β 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 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

  9. Pancreatic Endoderm-Derived From Diabetic Patient-Specific Induced Pluripotent Stem Cell Generates Glucose-Responsive Insulin-Secreting Cells.

    Science.gov (United States)

    Rajaei, Bahareh; Shamsara, Mehdi; Amirabad, Leila Mohammadi; Massumi, Mohammad; Sanati, Mohammad Hossein

    2017-10-01

    Human-induced pluripotent stem cells (hiPSCs) can potentially serve as an invaluable source for cell replacement therapy and allow the creation of patient- and disease-specific stem cells without the controversial use of embryos and avoids any immunological incompatibility. The generation of insulin-producing pancreatic β-cells from pluripotent stem cells in vitro provides an unprecedented cell source for personal drug discovery and cell transplantation therapy in diabetes. A new five-step protocol was introduced in this study, effectively induced hiPSCs to differentiate into glucose-responsive insulin-producing cells. This process mimics in vivo pancreatic organogenesis by directing cells through stages resembling definitive endoderm, primitive gut-tube endoderm, posterior foregut, pancreatic endoderm, and endocrine precursor. Each stage of differentiation were characterized by stage-specific markers. The produced cells exhibited many properties of functional β-cells, including expression of critical β-cells transcription factors, the potency to secrete C-peptide in response to high levels of glucose and the presence of mature endocrine secretory granules. This high efficient differentiation protocol, established in this study, yielded 79.18% insulin-secreting cells which were responsive to glucose five times higher than the basal level. These hiPSCs-derived glucose-responsive insulin-secreting cells might provide a promising approach for the treatment of type I diabetes mellitus. J. Cell. Physiol. 232: 2616-2625, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Expression of an insulin/interleukin-1 receptor antagonist hybrid gene in insulin-producing cell lines (HIT-T15 and NIT-1) confers resistance against interleukin-1-induced nitric oxide production.

    Science.gov (United States)

    Welsh, N; Bendtzen, K; Welsh, M

    1995-01-01

    A hybrid gene consisting of the insulin gene enhancer/promoter region, the signal sequence, the insulin B- and C-chains, and the human interleukin-1 receptor antagonist (IL-1ra) gene was constructed. This hybrid gene was transfected together with the pSV2-neo construct into the insulin-producing cell lines HIT-T15 and NIT-1. One of the geneticin-selected clones, HITra2, expressed a 1.4-kb mRNA, which hybridized both to insulin and IL-1ra-cDNA in Northern blot analysis. Three proteins, with the mol wt 23, 17, and 14 kD, were immunoprecipitated with anti-IL-1ra antibodies from [35S]methionine-labeled HITra2 cells. Both at a low and at a high glucose concentration, 4-5 ng of IL-1ra/10(6) cells (ELISA) was released from these cells. On the other hand, a high glucose concentration evoked a three-fold increase in the release of insulin, suggesting that IL-1ra was released constitutively. Measured by nitrite production, transfected HIT, and NIT-1 cells exhibited a more than 10-fold decrease in IL-1 beta sensitivity. Since the conditioned culture media from the HITra2 cells exhibited an anti-IL-1 beta activity of only 0.5 U/ml, and mixed culture of HITra2 cells and isolated rat islets prevented IL-1 beta induced inhibition of insulin release, it is likely that IL-1ra acts locally at the cell surface. It is concluded that expression of a hybrid insulin/IL-1ra gene confers resistance to IL-1 and that this technique may be used to elucidate the role of IL-1 in autoimmune disorders such as insulin-dependent diabetes mellitus. Images PMID:7706480

  11. MED25 is a mediator component of HNF4α-driven transcription leading to insulin secretion in pancreatic beta-cells.

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    Eun Hee Han

    Full Text Available Unique nuclear receptor Hepatocyte Nuclear Factor 4α (HNF4α is an essential transcriptional regulator for early development and proper function of pancreatic ß-cells, and its mutations are monogenic causes of a dominant inherited form of diabetes referred to as Maturity Onset Diabetes of the Young 1 (MODY1. As a gene-specific transcription factor, HNF4α exerts its function through various molecular interactions, but its protein recruiting network has not been fully characterized. Here we report the identification of MED25 as one of the HNF4α binding partners in pancreatic ß-cells leading to insulin secretion which is impaired in MODY patients. MED25 is one of the subunits of the Mediator complex that is required for induction of RNA polymerase II transcription by various transcription factors including nuclear receptors. This HNF4α-MED25 interaction was initially identified by a yeast-two-hybrid method, confirmed by in vivo and in vitro analyses, and proven to be mediated through the MED25-LXXLL motif in a ligand-independent manner. Reporter-gene based transcription assays and siRNA/shRNA-based gene silencing approaches revealed that this interaction is crucial for full activation of HNF4α-mediated transcription, especially expression of target genes implicated in glucose-stimulated insulin secretion. Selected MODY mutations at the LXXLL motif binding pocket disrupt these interactions and cause impaired insulin secretion through a 'loss-of-function' mechanism.

  12. The loss of Sirt1 in mouse pancreatic beta cells impairs insulin secretion by disrupting glucose sensing

    DEFF Research Database (Denmark)

    Luu, L; Dai, F F; Prentice, K J

    2013-01-01

    Sirtuin 1 (SIRT1) has emerged as a key metabolic regulator of glucose homeostasis and insulin secretion. Enhanced SIRT1 activity has been shown to be protective against diabetes, although the mechanisms remain largely unknown. The aim of this study was to determine how SIRT1 regulates insulin sec...

  13. DEFECTS IN INSULIN-SECRETION IN NIDDM - B-CELL GLUCOSE INSENSITIVITY OR GLUCOSE TOXICITY

    NARCIS (Netherlands)

    VANHAEFTEN, TW

    In NIDDM, first-phase insulin release to glucose is (almost) absent. However, in contrast to older studies which suggested that in NIDDM the B-cell is ''blind'' for glucose, recent evidence indicates that the B-cell is not insensitive for glucose as far as second phase release is concerned. This

  14. The H+/K+ ATPase Inhibitor SCH-28080 Inhibits Insulin Secretion and Induces Cell Death in INS-1E Rat Insulinoma Cells

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    Martin Jakab

    2017-10-01

    Full Text Available Background/Aims: Glucose-stimulated insulin secretion (GSIS of pancreatic β-cells involves glucose uptake and metabolism, closure of KATP channels and depolarization of the cell membrane potential (Vmem, activation of voltage-activated Ca2+ currents (ICav and influx of Ca2+, which eventually triggers hormone exocytosis. Beside this classical pathway, KATP-independent mechanisms such as changes in intracellular pH (pHi or cell volume, which also affect β-cell viability, can elicit or modify insulin release. In β-cells the regulation of pHi is mainly accomplished by Na+/H+ exchangers (NHEs. To investigate if other proton extrusion mechanisms than NHEs are involved in pH regulation, we tested for the presence of the non-gastric H+/K+ ATPase in rat insulinoma cells and assessed effects of the H+/K+ ATPase inhibitor SCH-28080 on insulin secretion, cell viability and apoptosis. Methods: In INS-1E cell cultures, H+/K+ ATPase gene and protein expression was analyzed by reverse transcription PCR and Western blotting. Intracellular pH (pHi recovery after acute acidic load was measured by NH4Cl prepulsing using BCECF. Insulin secretion was determined by ELISA from the cell culture supernatant. Vmem, K+ and Ca2+ currents were recorded using patch clamp. Overall cell responses were determined using resazurin (viability and cytotoxicity assays. The mean cell volume (MCV, cell granularity (side-scatter; SSC, phosphatidylserine (PS exposure, cell membrane integrity, caspase activity and the mitochondrial membrane potential (ΔΨm were measured by flow cytometry. Results: We found that the α-subunit of the non-gastric H+/K+ ATPase (HKα2 is expressed on mRNA and protein level. However, compared to rat colon tissue, in INS-1E cells mRNA abundance was very low. In NH4Cl prepulsing experiments no K+-dependent pHi recovery was observed under Na+-free extracellular conditions. Nonetheless within 1 h, 20 µM SCH-28080 inhibited GSIS by ∼50%, while basal release

  15. RFX6 Regulates Insulin Secretion by Modulating Ca2+ Homeostasis in Human β Cells

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    Vikash Chandra

    2014-12-01

    Full Text Available Development and function of pancreatic β cells involve the regulated activity of specific transcription factors. RFX6 is a transcription factor essential for mouse β cell differentiation that is mutated in monogenic forms of neonatal diabetes. However, the expression and functional roles of RFX6 in human β cells, especially in pathophysiological conditions, are poorly explored. We demonstrate the presence of RFX6 in adult human pancreatic endocrine cells. Using the recently developed human β cell line EndoC-βH2, we show that RFX6 regulates insulin gene transcription, insulin content, and secretion. Knockdown of RFX6 causes downregulation of Ca2+-channel genes resulting in the reduction in L-type Ca2+-channel activity that leads to suppression of depolarization-evoked insulin exocytosis. We also describe a previously unreported homozygous missense RFX6 mutation (p.V506G that is associated with neonatal diabetes, which lacks the capacity to activate the insulin promoter and to increase Ca2+-channel expression. Our data therefore provide insights for understanding certain forms of neonatal diabetes.

  16. Effects of exendin-4 on glucose tolerance, insulin secretion, and beta-cell proliferation depend on treatment dose, treatment duration and meal contents

    International Nuclear Information System (INIS)

    Arakawa, Masayuki; Ebato, Chie; Mita, Tomoya; Hirose, Takahisa; Kawamori, Ryuzo; Fujitani, Yoshio; Watada, Hirotaka

    2009-01-01

    Beta-cell proliferation is regulated by various metabolic demands including peripheral insulin resistance, obesity, and hyperglycemia. In addition to enhancement of glucose-induced insulin secretion, agonists for glucagon-like peptide-1 receptor (GLP-1R) stimulate proliferation and inhibit apoptosis of beta-cells, thereby probably preserve beta-cell mass. To evaluate the beta-cell preserving actions of GLP-1R agonists, we assessed the acute and chronic effects of exendin-4 on beta-cell proliferation, mass and glucose tolerance in C57BL/6J mice under various conditions. Short-term administration of high-dose exendin-4 transiently stimulated beta-cell proliferation. Comparative transcriptomic analysis showed upregulation of IGF-1 receptor and its downstream effectors in islets. Treatment of mice with exendin-4 daily for 4 weeks (long-term administration) and feeding high-fat diet resulted in significant inhibition of weight gain and improvement of glucose tolerance with reduced insulin secretion and beta-cell mass. These findings suggest that long-term GLP-1 treatment results in insulin sensitization of peripheral organs, rather than enhancement of beta-cell proliferation and function, particularly when animals are fed high-fat diet. Thus, the effects of exendin-4 on glucose tolerance, insulin secretion, and beta-cell proliferation largely depend on treatment dose, duration of treatment and meal contents. While GLP-1 enhances proliferation of beta-cells in some diabetic mice models, our results suggest that GLP-1 stimulates beta-cell growth only when expansion of beta-cell mass is required to meet metabolic demands.

  17. Effects of exendin-4 on glucose tolerance, insulin secretion, and beta-cell proliferation depend on treatment dose, treatment duration and meal contents

    Energy Technology Data Exchange (ETDEWEB)

    Arakawa, Masayuki; Ebato, Chie; Mita, Tomoya [Department of Medicine, Metabolism and Endocrinology, Juntendo University School of Medicine, Tokyo (Japan); Hirose, Takahisa [Department of Medicine, Metabolism and Endocrinology, Juntendo University School of Medicine, Tokyo (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University School of Medicine, Tokyo (Japan); Kawamori, Ryuzo [Department of Medicine, Metabolism and Endocrinology, Juntendo University School of Medicine, Tokyo (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University School of Medicine, Tokyo (Japan); Center for Beta Cell Biology and Regeneration, Juntendo University School of Medicine, Tokyo (Japan); Sportology Center, Juntendo University School of Medicine, Tokyo (Japan); Fujitani, Yoshio, E-mail: fujitani@juntendo.ac.jp [Department of Medicine, Metabolism and Endocrinology, Juntendo University School of Medicine, Tokyo (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University School of Medicine, Tokyo (Japan); Watada, Hirotaka, E-mail: hwatada@juntendo.ac.jp [Department of Medicine, Metabolism and Endocrinology, Juntendo University School of Medicine, Tokyo (Japan); Sportology Center, Juntendo University School of Medicine, Tokyo (Japan)

    2009-12-18

    Beta-cell proliferation is regulated by various metabolic demands including peripheral insulin resistance, obesity, and hyperglycemia. In addition to enhancement of glucose-induced insulin secretion, agonists for glucagon-like peptide-1 receptor (GLP-1R) stimulate proliferation and inhibit apoptosis of beta-cells, thereby probably preserve beta-cell mass. To evaluate the beta-cell preserving actions of GLP-1R agonists, we assessed the acute and chronic effects of exendin-4 on beta-cell proliferation, mass and glucose tolerance in C57BL/6J mice under various conditions. Short-term administration of high-dose exendin-4 transiently stimulated beta-cell proliferation. Comparative transcriptomic analysis showed upregulation of IGF-1 receptor and its downstream effectors in islets. Treatment of mice with exendin-4 daily for 4 weeks (long-term administration) and feeding high-fat diet resulted in significant inhibition of weight gain and improvement of glucose tolerance with reduced insulin secretion and beta-cell mass. These findings suggest that long-term GLP-1 treatment results in insulin sensitization of peripheral organs, rather than enhancement of beta-cell proliferation and function, particularly when animals are fed high-fat diet. Thus, the effects of exendin-4 on glucose tolerance, insulin secretion, and beta-cell proliferation largely depend on treatment dose, duration of treatment and meal contents. While GLP-1 enhances proliferation of beta-cells in some diabetic mice models, our results suggest that GLP-1 stimulates beta-cell growth only when expansion of beta-cell mass is required to meet metabolic demands.

  18. PPAR-γ activation increases insulin secretion through the up-regulation of the free fatty acid receptor GPR40 in pancreatic β-cells.

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    Hyo-Sup Kim

    Full Text Available BACKGROUND: It has been reported that peroxisome proliferator-activated receptor (PPAR-γ and their synthetic ligands have direct effects on pancreatic β-cells. We investigated whether PPAR-γ activation stimulates insulin secretion through the up-regulation of GPR40 in pancreatic β-cells. METHODS: Rat insulinoma INS-1 cells and primary rat islets were treated with rosiglitazone (RGZ and/or adenoviral PPAR-γ overexpression. OLETF rats were treated with RGZ. RESULTS: PPAR-γ activation with RGZ and/or adenoviral PPAR-γ overexpression increased free fatty acid (FFA receptor GPR40 expression, and increased insulin secretion and intracellular calcium mobilization, and was blocked by the PLC inhibitors, GPR40 RNA interference, and GLUT2 RNA interference. As a downstream signaling pathway of intracellular calcium mobilization, the phosphorylated levels of CaMKII and CREB, and the downstream IRS-2 and phospho-Akt were significantly increased. Despite of insulin receptor RNA interference, the levels of IRS-2 and phospho-Akt was still maintained with PPAR-γ activation. In addition, the β-cell specific gene expression, including Pdx-1 and FoxA2, increased in a GPR40- and GLUT2-dependent manner. The levels of GPR40, phosphorylated CaMKII and CREB, and β-cell specific genes induced by RGZ were blocked by GW9662, a PPAR-γ antagonist. Finally, PPAR-γ activation up-regulated β-cell gene expressions through FoxO1 nuclear exclusion, independent of the insulin signaling pathway. Based on immunohistochemical staining, the GLUT2, IRS-2, Pdx-1, and GPR40 were more strongly expressed in islets from RGZ-treated OLETF rats compared to control islets. CONCLUSION: These observations suggest that PPAR-γ activation with RGZ and/or adenoviral overexpression increased intracellular calcium mobilization, insulin secretion, and β-cell gene expression through GPR40 and GLUT2 gene up-regulation.

  19. Sweet taste receptor expressed in pancreatic beta-cells activates the calcium and cyclic AMP signaling systems and stimulates insulin secretion.

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    Yuko Nakagawa

    Full Text Available BACKGROUND: Sweet taste receptor is expressed in the taste buds and enteroendocrine cells acting as a sugar sensor. We investigated the expression and function of the sweet taste receptor in MIN6 cells and mouse islets. METHODOLOGY/PRINCIPAL FINDINGS: The expression of the sweet taste receptor was determined by RT-PCR and immunohistochemistry. Changes in cytoplasmic Ca(2+ ([Ca(2+](c and cAMP ([cAMP](c were monitored in MIN6 cells using fura-2 and Epac1-camps. Activation of protein kinase C was monitored by measuring translocation of MARCKS-GFP. Insulin was measured by radioimmunoassay. mRNA for T1R2, T1R3, and gustducin was expressed in MIN6 cells. In these cells, artificial sweeteners such as sucralose, succharin, and acesulfame-K increased insulin secretion and augmented secretion induced by glucose. Sucralose increased biphasic increase in [Ca(2+](c. The second sustained phase was blocked by removal of extracellular calcium and addition of nifedipine. An inhibitor of inositol(1, 4, 5-trisphophate receptor, 2-aminoethoxydiphenyl borate, blocked both phases of [Ca(2+](c response. The effect of sucralose on [Ca(2+](c was inhibited by gurmarin, an inhibitor of the sweet taste receptor, but not affected by a G(q inhibitor. Sucralose also induced sustained elevation of [cAMP](c, which was only partially inhibited by removal of extracellular calcium and nifedipine. Finally, mouse islets expressed T1R2 and T1R3, and artificial sweeteners stimulated insulin secretion. CONCLUSIONS: Sweet taste receptor is expressed in beta-cells, and activation of this receptor induces insulin secretion by Ca(2+ and cAMP-dependent mechanisms.

  20. Larval hemolymph of rhinoceros beetle, Allomyrina dichotoma, enhances insulin secretion through ATF3 gene expression in INS-1 pancreatic β-cells.

    Science.gov (United States)

    Kim, Seung-Whan; Suh, Hyun-Woo; Yoo, Bo-Kyung; Kwon, Kisang; Yu, Kweon; Choi, Ji-Young; Kwon, O-Yu

    2018-05-22

    In this study, we show that INS-1 pancreatic β-cells treated for 2 h with hemolymph of larvae of rhinoceros beetle, Allomyrina dichotoma, secreted about twice as much insulin compared to control cells without such treatment. Activating transcription factor 3 (ATF3) was the highest upregulated gene in DNA chip analysis. The A. dichotoma hemolymph dose-dependently induced increased expression levels of genes encoding ATF3 and insulin. Conversely, treatment with ATF3 siRNA inhibited expression levels of both genes and curbed insulin secretion. These results suggest that the A. dichotoma hemolymph has potential for treating and preventing diabetes or diabetes-related complications.

  1. Cucurbita ficifolia Bouché increases insulin secretion in RINm5F cells through an influx of Ca(2+) from the endoplasmic reticulum.

    Science.gov (United States)

    Miranda-Perez, Maria Elizabeth; Ortega-Camarillo, Clara; Del Carmen Escobar-Villanueva, Maria; Blancas-Flores, Gerardo; Alarcon-Aguilar, Francisco Javier

    2016-07-21

    Cucurbita ficifolia Bouché(C. ficifolia) is a plant used in Mexican traditional medicine to control type 2 diabetes (T2D). The hypoglycemic effect of the fruit of C. ficifolia has been demonstrated in different experimental models and in T2D patients. It has been proposed that D-chiro-inositol (DCI) is the active compound of the fruit. Additionally, it has been reported that C. ficifolia increases the mRNA expression of insulin and Kir 6.2 (a component of the ATP-sensitive potassium (K(+)ATP) channel, which is activated by sulphonylurea) in RINm5F cells. However, it remains unclear whether C. ficifolia and DCI causes the secretion of insulin by increasing the concentration of intracellular calcium ([Ca(2+)]i) through K(+)ATP channel blockage or from the reservoir in the endoplasmic reticulum (ER). The aqueous extract of C. ficifolia was obtained and standardized with regard to its DCI content. RINm5F pancreatic β-cells were incubated with different concentrations (50, 100, 200 and 400μM) of DCI alone or C. ficifolia (9, 18, 36 and 72µg of extract/mL), and the [Ca(2+)]i of the cells was quantified. The cells were preloaded with the Ca(2+) fluorescent dye fluo4-acetoxymethyl ester (AM) and visualized by confocal microscopy. Insulin secretion was measured by an ELISA method. Subsequently, the effect of C. ficifolia on the K(+)ATP channel was evaluated. In this case, the blocker activator diazoxide was used to inhibit the C. ficifolia-induced calcium influx. In addition, the inositol 1,4,5-trisphosphate (IP3)-receptor-selective inhibitor 2-amino-thoxydiphenylborate (2-APB) was used to inhibit the influx of calcium from the ER that was induced by C. ficifolia. It was found that DCI alone did not increase [Ca(2+)]i or insulin secretion. In contrast, treatment with C. ficifolia increased [Ca(2+)]i 10-fold compared with the control group. Insulin secretion increased by 46.9%. In the presence of diazoxide, C. ficifolia decreased [Ca(2+)]i by 50%, while insulin secretion

  2. Oral delivery of bioencapsulated exendin-4 expressed in chloroplasts lowers blood glucose level in mice and stimulates insulin secretion in beta-TC6 cells.

    Science.gov (United States)

    Kwon, Kwang-Chul; Nityanandam, Ramya; New, James S; Daniell, Henry

    2013-01-01

    Glucagon-like peptide (GLP-1) increases insulin secretion but is rapidly degraded (half-life: 2 min in circulation). GLP-1 analogue, exenatide (Byetta) has a longer half-life (3.3-4 h) with potent insulinotropic effects but requires cold storage, daily abdominal injections with short shelf life. Because patients with diabetes take >60 000 injections in their life time, alternative delivery methods are highly desired. Exenatide is ideal for oral delivery because insulinotropism is glucose dependent, with reduced risk of hypoglycaemia even at higher doses. Therefore, exendin-4 (EX4) was expressed as a cholera toxin B subunit (CTB)-fusion protein in tobacco chloroplasts to facilitate bioencapsulation within plant cells and transmucosal delivery in the gut via GM1 receptors present in the intestinal epithelium. The transgene integration was confirmed by PCR and Southern blot analysis. Expression level of CTB-EX4 reached up to 14.3% of total leaf protein (TLP). Lyophilization of leaf material increased therapeutic protein concentration by 12- to 24-fold, extended their shelf life up to 15 months when stored at room temperature and eliminated microbes present in fresh leaves. The pentameric structure, disulphide bonds and functionality of CTB-EX4 were well preserved in lyophilized materials. Chloroplast-derived CTB-EX4 showed increased insulin secretion similar to the commercial EX4 in beta-TC6, a mouse pancreatic cell line. Even when 5000-fold excess dose of CTB-EX4 was orally delivered, it stimulated insulin secretion similar to the intraperitoneal injection of commercial EX4 but did not cause hypoglycaemia in mice. Oral delivery of the bioencapsulated EX4 should eliminate injections, increase patient compliance/convenience and significantly lower their cost. © 2012 The Authors Plant Biotechnology Journal © 2012 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

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

    Science.gov (United States)

    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

    2016-06-01

    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.

  4. Co-culture of clonal beta cells with GLP-1 and glucagon-secreting cell line impacts on beta cell insulin secretion, proliferation and susceptibility to cytotoxins.

    Science.gov (United States)

    Green, Alastair D; Vasu, Srividya; Moffett, R Charlotte; Flatt, Peter R

    2016-06-01

    We investigated the direct effects on insulin releasing MIN6 cells of chronic exposure to GLP-1, glucagon or a combination of both peptides secreted from GLUTag L-cell and αTC1.9 alpha-cell lines in co-culture. MIN6, GLUTag and αTC1.9 cell lines exhibited high cellular hormone content and release of insulin, GLP-1 and glucagon, respectively. Co-culture of MIN6 cells with GLUTag cells significantly increased cellular insulin content, beta-cell proliferation, insulin secretory responses to a range of established secretogogues and afforded protection against exposure cytotoxic concentrations of glucose, lipid, streptozotocin or cytokines. Benefits of co-culture of MIN6 cells with αTC1.9 alphacells were limited to enhanced beta-cell proliferation with marginal positive actions on both insulin secretion and cellular protection. In contrast, co-culture of MIN6 with GLUTag cells plus αTC1.9 cells, markedly enhanced both insulin secretory responses and protection against beta-cell toxins compared with co-culture with GLUTag cells alone. These data indicate important long-term effects of conjoint GLP-1 and glucagon exposure on beta-cell function. This illustrates the possible functional significance of alpha-cell GLP-1 production as well as direct beneficial effects of dual agonism at beta-cell GLP-1 and glucagon receptors. Copyright © 2016 Elsevier B.V. and Société française de biochimie et biologie Moléculaire (SFBBM). All rights reserved.

  5. The ethyl acetate fraction of corn silk exhibits dual antioxidant and anti-glycation activities and protects insulin-secreting cells from glucotoxicity.

    Science.gov (United States)

    Chang, Chia-Chuan; Yuan, Wei; Roan, Hsiao-Yuh; Chang, Jia-Ling; Huang, Hsiu-Chen; Lee, Yu-Ching; Tsay, Huey Jen; Liu, Hui-Kang

    2016-11-03

    In this study, we aimed to develop a Stigmata Maydis (corn silk) fraction with dual bio-activities against oxidative stress and protein glycation to protect β-cells from diabetes-induced failure. Corn silk fractions were prepared by partition and chemically characterised by thin-layer chromatography. Free radical scavenging assay, glycation assay, and cell-based viability test (neutral red) were employed to decide the best fraction. Cell death analysis was executed by annexin V/ Propidium iodide staining. Cell proliferation was measured by WST-1. Finally, β-cell function was evaluated by β-cell marker gene expression (RT-PCR) and acute insulin secretion test. Four corn silk fractions were prepared from an ethanolic crude extract of corn silk. In vitro assays indicate ethyl acetate fraction (YMS-EA) was the most potent fraction. YMS-EA also attenuated the hydrogen peroxide- or methylglyoxal-induced induction of reactive oxygen species, reduction of cell viability, and inhibition of cell proliferation. However, YMS-EA was unable to prevent hydrogen peroxide-induced apoptosis or advanced glycation end-products-induced toxicity. Under hyperglycemic conditions, YMS-EA effectively reduced ROS levels, improved mRNA expression of insulin, glucokinase, and PDX-1, and enhanced glucose-stimulated insulin secretion. The similarity of bioactivities among apigenin, luteolin, and YMS-EA indicated that dual activities of YMS-EA might be derived from those compounds. We concluded that YMS-EA fraction could be developed as a preventive food agent against the glucotoxicity to β-cells in Type 2 diabetes.

  6. The GLP-1 analogue liraglutide improves first-phase insulin secretion and maximal beta-cell secretory capacity over 14 weeks of therapy in subjects with Type 2 diabetes

    DEFF Research Database (Denmark)

    Madsbad, Sten; Vilsbøll, Tina; Brock, Birgitte

    Aims: We investigated the clinical effect of liraglutide, a long- acting GLP-1 analogue, on insulin secretion in Type 2 diabetes. Methods: Thirty-nine subjects (28 completed) from a randomised trial received a hyperglycaemic clamp (20 mM) with intravenous arginine stimulation, and an insulin...... group. Conclusion: In subjects with Type 2 diabetes, 14 weeks’ once-daily liraglutide (1.25 and 1.9 mg/day) markedly improves beta-cell function, significantly increases first-phase insulin secretion and maximal beta-cell secretory capacity....

  7. Essential roles of aspartate aminotransferase 1 and vesicular glutamate transporters in β-cell glutamate signaling for incretin-induced insulin secretion.

    Directory of Open Access Journals (Sweden)

    Naoya Murao

    Full Text Available Incretins (GLP-1 and GIP potentiate insulin secretion through cAMP signaling in pancreatic β-cells in a glucose-dependent manner. We recently proposed a mechanistic model of incretin-induced insulin secretion (IIIS that requires two critical processes: 1 generation of cytosolic glutamate through the malate-aspartate (MA shuttle in glucose metabolism and 2 glutamate transport into insulin granules by cAMP signaling to promote insulin granule exocytosis. To directly prove the model, we have established and characterized CRISPR/Cas9-engineered clonal mouse β-cell lines deficient for the genes critical in these two processes: aspartate aminotransferase 1 (AST1, gene symbol Got1, a key enzyme in the MA shuttle, which generates cytosolic glutamate, and the vesicular glutamate transporters (VGLUT1, VGLUT2, and VGLUT3, gene symbol Slc17a7, Slc17a6, and Slc17a8, respectively, which participate in glutamate transport into secretory vesicles. Got1 knockout (KO β-cell lines were defective in cytosolic glutamate production from glucose and showed impaired IIIS. Unexpectedly, different from the previous finding that global Slc17a7 KO mice exhibited impaired IIIS from pancreatic islets, β-cell specific Slc17a7 KO mice showed no significant impairment in IIIS, as assessed by pancreas perfusion experiment. Single Slc17a7 KO β-cell lines also retained IIIS, probably due to compensatory upregulation of Slc17a6. Interestingly, triple KO of Slc17a7, Slc17a6, and Slc17a8 diminished IIIS, which was rescued by exogenously introduced wild-type Slc17a7 or Slc17a6 genes. The present study provides direct evidence for the essential roles of AST1 and VGLUTs in β-cell glutamate signaling for IIIS and also shows the usefulness of the CRISPR/Cas9 system for studying β-cells by simultaneous disruption of multiple genes.

  8. Chronic suppression of acetyl-CoA carboxylase 1 in beta-cells impairs insulin secretion via inhibition of glucose rather than lipid metabolism.

    Science.gov (United States)

    Ronnebaum, Sarah M; Joseph, Jamie W; Ilkayeva, Olga; Burgess, Shawn C; Lu, Danhong; Becker, Thomas C; Sherry, A Dean; Newgard, Christopher B

    2008-05-23

    Acetyl-CoA carboxylase 1 (ACC1) currently is being investigated as a target for treatment of obesity-associated dyslipidemia and insulin resistance. To investigate the effects of ACC1 inhibition on insulin secretion, three small interfering RNA (siRNA) duplexes targeting ACC1 (siACC1) were transfected into the INS-1-derived cell line, 832/13; the most efficacious duplex was also cloned into an adenovirus and used to transduce isolated rat islets. Delivery of the siACC1 duplexes decreased ACC1 mRNA by 60-80% in 832/13 cells and islets and enzyme activity by 46% compared with cells treated with a non-targeted siRNA. Delivery of siACC1 decreased glucose-stimulated insulin secretion (GSIS) by 70% in 832/13 cells and by 33% in islets. Surprisingly, siACC1 treatment decreased glucose oxidation by 49%, and the ATP:ADP ratio by 52%, accompanied by clear decreases in pyruvate cycling activity and tricarboxylic acid cycle intermediates. Exposure of siACC1-treated cells to the pyruvate cycling substrate dimethylmalate restored GSIS to normal without recovery of the depressed ATP:ADP ratio. In siACC1-treated cells, glucokinase protein levels were decreased by 25%, which correlated with a 36% decrease in glycogen synthesis and a 33% decrease in glycolytic flux. Furthermore, acute addition of the ACC1 inhibitor 5-(tetradecyloxy)-2-furoic acid (TOFA) to beta-cells suppressed [(14)C]glucose incorporation into lipids but had no effect on GSIS, whereas chronic TOFA administration suppressed GSIS and glucose metabolism. In sum, chronic, but not acute, suppression of ACC1 activity impairs GSIS via inhibition of glucose rather than lipid metabolism. These findings raise concerns about the use of ACC inhibitors for diabetes therapy.

  9. Chronic Suppression of Acetyl-CoA Carboxylase 1 in β-Cells Impairs Insulin Secretion via Inhibition of Glucose Rather Than Lipid Metabolism*

    Science.gov (United States)

    Ronnebaum, Sarah M.; Joseph, Jamie W.; Ilkayeva, Olga; Burgess, Shawn C.; Lu, Danhong; Becker, Thomas C.; Sherry, A. Dean; Newgard, Christopher B.

    2008-01-01

    Acetyl-CoA carboxylase 1 (ACC1) currently is being investigated as a target for treatment of obesity-associated dyslipidemia and insulin resistance. To investigate the effects of ACC1 inhibition on insulin secretion, three small interfering RNA (siRNA) duplexes targeting ACC1 (siACC1) were transfected into the INS-1-derived cell line, 832/13; the most efficacious duplex was also cloned into an adenovirus and used to transduce isolated rat islets. Delivery of the siACC1 duplexes decreased ACC1 mRNA by 60–80% in 832/13 cells and islets and enzyme activity by 46% compared with cells treated with a non-targeted siRNA. Delivery of siACC1 decreased glucose-stimulated insulin secretion (GSIS) by 70% in 832/13 cells and by 33% in islets. Surprisingly, siACC1 treatment decreased glucose oxidation by 49%, and the ATP:ADP ratio by 52%, accompanied by clear decreases in pyruvate cycling activity and tricarboxylic acid cycle intermediates. Exposure of siACC1-treated cells to the pyruvate cycling substrate dimethylmalate restored GSIS to normal without recovery of the depressed ATP:ADP ratio. In siACC1-treated cells, glucokinase protein levels were decreased by 25%, which correlated with a 36% decrease in glycogen synthesis and a 33% decrease in glycolytic flux. Furthermore, acute addition of the ACC1 inhibitor 5-(tetradecyloxy)-2-furoic acid (TOFA) to β-cells suppressed [14C]glucose incorporation into lipids but had no effect on GSIS, whereas chronic TOFA administration suppressed GSIS and glucose metabolism. In sum, chronic, but not acute, suppression of ACC1 activity impairs GSIS via inhibition of glucose rather than lipid metabolism. These findings raise concerns about the use of ACC inhibitors for diabetes therapy. PMID:18381287

  10. Glucose, other secretagogues, and nerve growth factor stimulate mitogen-activated protein kinase in the insulin-secreting beta-cell line, INS-1

    DEFF Research Database (Denmark)

    Frödin, M; Sekine, N; Roche, E

    1995-01-01

    The signaling pathways whereby glucose and hormonal secretagogues regulate insulin-secretory function, gene transcription, and proliferation of pancreatic beta-cells are not well defined. We show that in the glucose-responsive beta-cell line INS-1, major secretagogue-stimulated signaling pathways...... converge to activate 44-kDa mitogen-activated protein (MAP) kinase. Thus, glucose-induced insulin secretion was found to be associated with a small stimulatory effect on 44-kDa MAP kinase, which was synergistically enhanced by increased levels of intracellular cAMP and by the hormonal secretagogues......-1. Phorbol ester, an activator of protein kinase C, stimulated 44-kDa MAP kinase by both Ca(2+)-dependent and -independent pathways. Nerve growth factor, independently of changes in cytosolic Ca2+, efficiently stimulated 44-kDa MAP kinase without causing insulin release, indicating that activation...

  11. Indian culinary plants enhance glucose-induced insulin secretion and glucose consumption in INS-1 β-cells and 3T3-L1 adipocytes.

    Science.gov (United States)

    Kaur, Lovedeep; Han, Kyoung-Sik; Bains, Kiran; Singh, Harjinder

    2011-12-01

    Six Indian plants, commonly used as culinary plants, herbs or spices (kikar; jamun; neem; harad; fenugreek; bitter gourd), were screened and compared for their antidiabetic potential in vitro. Aqueous plant extracts were prepared and assessed for their effect on the insulin secretion activity of rat pancreatic INS-1 β-cells and glucose consumption in mouse 3T3-L1 adipocytes in order to study their specific mechanisms of action. The effect of the plant extract concentration (25-1000μg/ml) on insulin release and glucose consumption was also studied. All the extracts had a significant stimulatory effect on the insulin secretion of INS-1 cells. In the presence of kikar extract (100μg/ml), an increase of 228% in insulin release was recorded compared to the control (5.6mM glucose) whereas that was 270% and 367% in the presence of kikar and jamun extracts (500μg/ml), respectively. 3T3-L1 cells treated with jamun extract (100μg/ml) exhibited the highest increase in glucose consumption by the cells (94%, compared with the control) followed by harad (53%) and fenugreek (50%) extracts. A significant inhibitory effect of the fenugreek, kikar and jamun extracts on glucose diffusion across a dialysis membrane suggested that these extracts could partly act by decreasing glucose absorption in the small intestine. The results showed that a combination of these plants in diet could help in the management of both type 1 and type 2 diabetes. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Influence of High Aspect Ratio Vessel Cell Culture on TNF-Alpha, Insulin Secretion and Glucose Homeostasis in Pancreatic Islets of Langerhans from Wistar Furth Rats

    Science.gov (United States)

    Tobin, Brian W.a; Leeper-Woodford, Sandra K.

    1999-01-01

    The present studies were carried out to determine the influence of a ground based microgravity paradigm, utilizing the High Aspect Ratio Vessel (HARV) cell culture upon lipopolysaccharide (LPS) stimulated tumor necrosis factor alpha (TNF-alpha) production of pancreatic islets of Langerhans. An additional aim was to elucidate alterations in insulin secretion and glucose utilization using the HARV low shear, gravity averaged vector, cell culture technique. Islets were isolated (1726 +/- 117, 150 micron islet equivalent units) from Wistar Furth rats and assigned to four treatment groups: 1) HARV, 2) HARV plus LPS, 3) static culture, 4) static culture plus LPS. Following 48 hours of culture, insulin concentration was increased in both HARV and static cultures (palpha (L929 cytotoxicity assay) and was measured at selected time points for 48 hours. TNF-alpha was significantly increased in LPS-induced HARV and static cultures, yet the increase was more pronounced in the static culture group (palpha is associated with a decreased insulin secretion is intriguing, both as it relates to in-flight investigations, and as it may provide insight into the pathophysiology of Type I and Type 11 diabetes. Glucose concentration in islet medium was lesser throughout the experiment in static cultures, suggesting a decreased reliance upon glucose as a metabolic substrate in the islets cultured in HARVS. In conclusion, the present studies demonstrate alterations in LPS induced TNF-alpha production of pancreatic islets of Langerhans, favoring a lesser TNF production in the microgravity HARV paradigm. Additionally, alterations in fuel homeostasis may be promulgated by HARV culture. The clinical and physiological significance of these observations remains to be determined.

  13. Store-operated Ca2+ Entry Mediated by Orai1 and TRPC1 Participates to Insulin Secretion in Rat β-Cells*

    Science.gov (United States)

    Sabourin, Jessica; Le Gal, Loïc; Saurwein, Lisa; Haefliger, Jacques-Antoine; Raddatz, Eric; Allagnat, Florent

    2015-01-01

    Store-operated Ca2+ channels (SOCs) are voltage-independent Ca2+ channels activated upon depletion of the endoplasmic reticulum Ca2+ stores. Early studies suggest the contribution of such channels to Ca2+ homeostasis in insulin-secreting pancreatic β-cells. However, their composition and contribution to glucose-stimulated insulin secretion (GSIS) remains unclear. In this study, endoplasmic reticulum Ca2+ depletion triggered by acetylcholine (ACh) or thapsigargin stimulated the formation of a ternary complex composed of Orai1, TRPC1, and STIM1, the key proteins involved in the formation of SOCs. Ca2+ imaging further revealed that Orai1 and TRPC1 are required to form functional SOCs and that these channels are activated by STIM1 in response to thapsigargin or ACh. Pharmacological SOCs inhibition or dominant negative blockade of Orai1 or TRPC1 using the specific pore mutants Orai1-E106D and TRPC1-F562A impaired GSIS in rat β-cells and fully blocked the potentiating effect of ACh on secretion. In contrast, pharmacological or dominant negative blockade of TRPC3 had no effect on extracellular Ca2+ entry and GSIS. Finally, we observed that prolonged exposure to supraphysiological glucose concentration impaired SOCs function without altering the expression levels of STIM1, Orai1, and TRPC1. We conclude that Orai1 and TRPC1, which form SOCs regulated by STIM1, play a key role in the effect of ACh on GSIS, a process that may be impaired in type 2 diabetes. PMID:26494622

  14. Enrichment of human embryonic stem cell-derived NKX6.1-expressing pancreatic progenitor cells accelerates the maturation of insulin-secreting cells in vivo.

    Science.gov (United States)

    Rezania, Alireza; Bruin, Jennifer E; Xu, Jean; Narayan, Kavitha; Fox, Jessica K; O'Neil, John J; Kieffer, Timothy J

    2013-11-01

    Human embryonic stem cells (hESCs) are considered a potential alternative to cadaveric islets as a source of transplantable cells for treating patients with diabetes. We previously described a differentiation protocol to generate pancreatic progenitor cells from hESCs, composed of mainly pancreatic endoderm (PDX1/NKX6.1-positive), endocrine precursors (NKX2.2/synaptophysin-positive, hormone/NKX6.1-negative), and polyhormonal cells (insulin/glucagon-positive, NKX6.1-negative). However, the relative contributions of NKX6.1-negative versus NKX6.1-positive cell fractions to the maturation of functional β-cells remained unclear. To address this question, we generated two distinct pancreatic progenitor cell populations using modified differentiation protocols. Prior to transplant, both populations contained a high proportion of PDX1-expressing cells (~85%-90%) but were distinguished by their relatively high (~80%) or low (~25%) expression of NKX6.1. NKX6.1-high and NKX6.1-low progenitor populations were transplanted subcutaneously within macroencapsulation devices into diabetic mice. Mice transplanted with NKX6.1-low cells remained hyperglycemic throughout the 5-month post-transplant period whereas diabetes was reversed in NKX6.1-high recipients within 3 months. Fasting human C-peptide levels were similar between groups throughout the study, but only NKX6.1-high grafts displayed robust meal-, glucose- and arginine-responsive insulin secretion as early as 3 months post-transplant. NKX6.1-low recipients displayed elevated fasting glucagon levels. Theracyte devices from both groups contained almost exclusively pancreatic endocrine tissue, but NKX6.1-high grafts contained a greater proportion of insulin-positive and somatostatin-positive cells, whereas NKX6.1-low grafts contained mainly glucagon-expressing cells. Insulin-positive cells in NKX6.1-high, but not NKX6.1-low grafts expressed nuclear MAFA. Collectively, this study demonstrates that a pancreatic endoderm

  15. FGF-2b and h-PL Transform Duct and Non-Endocrine Human Pancreatic Cells into Endocrine Insulin Secreting Cells by Modulating Differentiating Genes

    Directory of Open Access Journals (Sweden)

    Giulia Donadel

    2017-10-01

    Full Text Available Background: Diabetes mellitus (DM is a multifactorial disease orphan of a cure. Regenerative medicine has been proposed as novel strategy for DM therapy. Human fibroblast growth factor (FGF-2b controls β-cell clusters via autocrine action, and human placental lactogen (hPL-A increases functional β-cells. We hypothesized whether FGF-2b/hPL-A treatment induces β-cell differentiation from ductal/non-endocrine precursor(s by modulating specific genes expression. Methods: Human pancreatic ductal-cells (PANC-1 and non-endocrine pancreatic cells were treated with FGF-2b plus hPL-A at 500 ng/mL. Cytofluorimetry and Immunofluorescence have been performed to detect expression of endocrine, ductal and acinar markers. Bromodeoxyuridine incorporation and annexin-V quantified cells proliferation and apoptosis. Insulin secretion was assessed by RIA kit, and electron microscopy analyzed islet-like clusters. Results: Increase in PANC-1 duct cells de-differentiation into islet-like aggregates was observed after FGF-2b/hPL-A treatment showing ultrastructure typical of islets-aggregates. These clusters, after stimulation with FGF-2b/hPL-A, had significant (p < 0.05 increase in insulin, C-peptide, pancreatic and duodenal homeobox 1 (PDX-1, Nkx2.2, Nkx6.1, somatostatin, glucagon, and glucose transporter 2 (Glut-2, compared with control cells. Markers of PANC-1 (Cytokeratin-19, MUC-1, CA19-9 were decreased (p < 0.05. These aggregates after treatment with FGF-2b/hPL-A significantly reduced levels of apoptosis. Conclusions: FGF-2b and hPL-A are promising candidates for regenerative therapy in DM by inducing de-differentiation of stem cells modulating pivotal endocrine genes.

  16. Cell death and impairment of glucose-stimulated insulin secretion induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the β-cell line INS-1E

    International Nuclear Information System (INIS)

    Piaggi, Simona; Novelli, Michela; Martino, Luisa; Masini, Matilde; Raggi, Chiara; Orciuolo, Enrico; Masiello, Pellegrino; Casini, Alessandro; De Tata, Vincenzo

    2007-01-01

    The aim of this research was to characterize 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity on the insulin-secreting β-cell line INS-1E. A sharp decline of cell survival (below 20%) was observed after 1 h exposure to TCDD concentrations between 12.5 and 25 nM. Ultrastructurally, β-cell death was characterized by extensive degranulation, appearance of autophagic vacuoles, and peripheral nuclear condensation. Cytotoxic concentrations of TCDD rapidly induced a dose-dependent increase in intracellular calcium concentration. Blocking calcium entry by EGTA significantly decreased TCDD cytotoxicity. TCDD was also able to rapidly induce mitochondrial depolarization. Interestingly, 1 h exposition of INS-1E cells to very low TCDD concentrations (0.05-1 nM) dramatically impaired glucose-stimulated but not KCl-stimulated insulin secretion. In conclusion, our results clearly show that TCDD exerts a direct β-cell cytotoxic effect at concentrations of 15-25 nM, but also markedly impairs glucose-stimulated insulin secretion at concentrations 20 times lower than these. On the basis of this latter observation we suggest that pancreatic β-cells could be considered a specific and sensitive target for dioxin toxicity

  17. Neurotrophin Signaling Is Required for Glucose-Induced Insulin Secretion.

    Science.gov (United States)

    Houtz, Jessica; Borden, Philip; Ceasrine, Alexis; Minichiello, Liliana; Kuruvilla, Rejji

    2016-11-07

    Insulin secretion by pancreatic islet β cells is critical for glucose homeostasis, and a blunted β cell secretory response is an early deficit in type 2 diabetes. Here, we uncover a regulatory mechanism by which glucose recruits vascular-derived neurotrophins to control insulin secretion. Nerve growth factor (NGF), a classical trophic factor for nerve cells, is expressed in pancreatic vasculature while its TrkA receptor is localized to islet β cells. High glucose rapidly enhances NGF secretion and increases TrkA phosphorylation in mouse and human islets. Tissue-specific deletion of NGF or TrkA, or acute disruption of TrkA signaling, impairs glucose tolerance and insulin secretion in mice. We show that internalized TrkA receptors promote insulin granule exocytosis via F-actin reorganization. Furthermore, NGF treatment augments glucose-induced insulin secretion in human islets. These findings reveal a non-neuronal role for neurotrophins and identify a new regulatory pathway in insulin secretion that can be targeted to ameliorate β cell dysfunction. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Reversible immortalization of Nestin-positive precursor cells from pancreas and differentiation into insulin-secreting cells

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Pei; Li, Li; Qi, Hui [The Clinical Medical Research Center, The Second Clinical Medical College (Shenzhen People' s Hospital), Jinan University, 518020 Shenzhen (China); Zhou, Han-xin [Department of General Surgery, First Hospital (Shenzhen Second People' s Hospital) of Shenzhen University, 518020 Shenzhen (China); Deng, Chun-yan [The Clinical Medical Research Center, The Second Clinical Medical College (Shenzhen People' s Hospital), Jinan University, 518020 Shenzhen (China); Li, Fu-rong, E-mail: frli62@yahoo.com [The Clinical Medical Research Center, The Second Clinical Medical College (Shenzhen People' s Hospital), Jinan University, 518020 Shenzhen (China); Shenzhen Institution of Gerontology, 518020 Shenzhen (China)

    2012-02-10

    Highlights: Black-Right-Pointing-Pointer The NPPCs from mouse pancreas were isolated. Black-Right-Pointing-Pointer Tet-on system for SV40 large in NPPCs was used to get RINPPCs. Black-Right-Pointing-Pointer The RINPPCs can undergo at least 80 population doublings without senescence. Black-Right-Pointing-Pointer The RINPPCs can be induced to differentiate into insulin-producing cells. Black-Right-Pointing-Pointer The combination of GLP-1 and sodium butyrate promoted the differentiation process. -- Abstract: Pancreatic stem cells or progenitor cells posses the ability of directed differentiation into pancreatic {beta} cells. However, these cells usually have limited proliferative capacity and finite lifespan in vitro. In the present study, Nestin-positive progenitor cells (NPPCs) from mouse pancreas that expressed the pancreatic stem cells or progenitor cell marker Nestin were isolated to obtain a sufficient number of differentiated pancreatic {beta} cells. Tet-on system for SV40 large T-antigen expression in NPPCs was used to achieve reversible immortalization. The reversible immortal Nestin-positive progenitor cells (RINPPCs) can undergo at least 80 population doublings without senescence in vitro while maintaining their biological and genetic characteristics. RINPPCs can be efficiently induced to differentiate into insulin-producing cells that contain a combination of glucagon-like peptide-1 (GLP-1) and sodium butyrate. The results of the present study can be used to explore transplantation therapy of type I diabetes mellitus.

  19. SAD-A potentiates glucose-stimulated insulin secretion as a mediator of glucagon-like peptide 1 response in pancreatic β cells.

    Science.gov (United States)

    Nie, Jia; Lilley, Brendan N; Pan, Y Albert; Faruque, Omar; Liu, Xiaolei; Zhang, Weiping; Sanes, Joshua R; Han, Xiao; Shi, Yuguang

    2013-07-01

    Type 2 diabetes is characterized by defective glucose-stimulated insulin secretion (GSIS) from pancreatic β cells, which can be restored by glucagon-like peptide 1 (GLP-1), an incretin hormone commonly used for the treatment of type 2 diabetes. However, molecular mechanisms by which GLP-1 affects glucose responsiveness in islet β cells remain poorly understood. Here we investigated a role of SAD-A, an AMP-activated protein kinase (AMPK)-related kinase, in regulating GSIS in mice with conditional SAD-A deletion. We show that selective deletion of SAD-A in pancreas impaired incretin's effect on GSIS, leading to glucose intolerance. Conversely, overexpression of SAD-A significantly enhanced GSIS and further potentiated GLP-1's effect on GSIS from isolated mouse islets. In support of SAD-A as a mediator of incretin response, SAD-A is expressed exclusively in pancreas and brain, the primary targeting tissues of GLP-1 action. Additionally, SAD-A kinase is activated in response to stimulation by GLP-1 through cyclic AMP (cAMP)/Ca(2+)-dependent signaling pathways in islet β cells. Furthermore, we identified Thr443 as a key autoinhibitory phosphorylation site which mediates SAD-A's effect on incretin response in islet β cells. Consequently, ablation of Thr443 significantly enhanced GLP-1's effect on GSIS from isolated mouse islets. Together, these findings identified SAD-A kinase as a pancreas-specific mediator of incretin response in islet β cells.

  20. Bridging the gap between protein carboxyl methylation and phospholipid methylation to understand glucose-stimulated insulin secretion from the pancreatic beta cell.

    Science.gov (United States)

    Kowluru, Anjaneyulu

    2008-01-15

    Recent findings have implicated post-translational modifications at C-terminal cysteines [e.g., methylation] of specific proteins [e.g., G-proteins] in glucose-stimulated insulin secretion [GSIS]. Furthermore, methylation at the C-terminal leucine of the catalytic subunit of protein phosphatase 2A [PP2Ac] has also been shown to be relevant for GSIS. In addition to these two classes of protein methyl transferases, a novel class of glucose-activated phospholipid methyl transferases have also been identified in the beta cell. These enzymes catalyze three successive methylations of phosphatidylethanolamine to yield phosphatidylcholine. The "newly formed" phosphatidylcholine is felt to induce alterations in the membrane fluidity, which might favor vesicular fusion with the plasma membrane for the exocytosis of insulin. The objectives of this commentary are to: (i) review the existing evidence on the regulation, by glucose and other insulin secretagogues, of post-translational carboxylmethylation [CML] of specific proteins in the beta cell; (ii) discuss the experimental evidence, which implicates regulation, by glucose and other insulin secretagogues, of phosphatidylethanolamine methylation in the islet beta cell; (iii) propose a model for potential cross-talk between the protein and lipid methylation pathways in the regulation of GSIS and (iv) highlight potential avenues for future research, including the development of specific pharmacological inhibitors to further decipher regulatory roles for these methylation reactions in islet beta cell function.

  1. Synapses of Amphids Defective (SAD-A) Kinase Promotes Glucose-stimulated Insulin Secretion through Activation of p21-activated Kinase (PAK1) in Pancreatic β-Cells*

    Science.gov (United States)

    Nie, Jia; Sun, Chao; Faruque, Omar; Ye, Guangming; Li, Jia; Liang, Qiangrong; Chang, Zhijie; Yang, Wannian; Han, Xiao; Shi, Yuguang

    2012-01-01

    The p21-activated kinase-1 (PAK1) is implicated in regulation of insulin exocytosis as an effector of Rho GTPases. PAK1 is activated by the onset of glucose-stimulated insulin secretion (GSIS) through phosphorylation of Thr-423, a major activation site by Cdc42 and Rac1. However, the kinase(s) that phosphorylates PAK1 at Thr-423 in islet β-cells remains elusive. The present studies identified SAD-A (synapses of amphids defective), a member of AMP-activated protein kinase-related kinases exclusively expressed in brain and pancreas, as a key regulator of GSIS through activation of PAK1. We show that SAD-A directly binds to PAK1 through its kinase domain. The interaction is mediated by the p21-binding domain (PBD) of PAK1 and requires both kinases in an active conformation. The binding leads to direct phosphorylation of PAK1 at Thr-423 by SAD-A, triggering the onset of GSIS from islet β-cells. Consequently, ablation of PAK1 kinase activity or depletion of PAK1 expression completely abolishes the potentiating effect of SAD-A on GSIS. Consistent with its role in regulating GSIS, overexpression of SAD-A in MIN6 islet β-cells significantly stimulated cytoskeletal remodeling, which is required for insulin exocytosis. Together, the present studies identified a critical role of SAD-A in the activation of PAK1 during the onset of insulin exocytosis. PMID:22669945

  2. Synapses of amphids defective (SAD-A) kinase promotes glucose-stimulated insulin secretion through activation of p21-activated kinase (PAK1) in pancreatic β-Cells.

    Science.gov (United States)

    Nie, Jia; Sun, Chao; Faruque, Omar; Ye, Guangming; Li, Jia; Liang, Qiangrong; Chang, Zhijie; Yang, Wannian; Han, Xiao; Shi, Yuguang

    2012-07-27

    The p21-activated kinase-1 (PAK1) is implicated in regulation of insulin exocytosis as an effector of Rho GTPases. PAK1 is activated by the onset of glucose-stimulated insulin secretion (GSIS) through phosphorylation of Thr-423, a major activation site by Cdc42 and Rac1. However, the kinase(s) that phosphorylates PAK1 at Thr-423 in islet β-cells remains elusive. The present studies identified SAD-A (synapses of amphids defective), a member of AMP-activated protein kinase-related kinases exclusively expressed in brain and pancreas, as a key regulator of GSIS through activation of PAK1. We show that SAD-A directly binds to PAK1 through its kinase domain. The interaction is mediated by the p21-binding domain (PBD) of PAK1 and requires both kinases in an active conformation. The binding leads to direct phosphorylation of PAK1 at Thr-423 by SAD-A, triggering the onset of GSIS from islet β-cells. Consequently, ablation of PAK1 kinase activity or depletion of PAK1 expression completely abolishes the potentiating effect of SAD-A on GSIS. Consistent with its role in regulating GSIS, overexpression of SAD-A in MIN6 islet β-cells significantly stimulated cytoskeletal remodeling, which is required for insulin exocytosis. Together, the present studies identified a critical role of SAD-A in the activation of PAK1 during the onset of insulin exocytosis.

  3. Influence of Flavonoids on Mechanism of Modulation of Insulin Secretion.

    Science.gov (United States)

    Soares, Juliana Mikaelly Dias; Pereira Leal, Ana Ediléia Barbosa; Silva, Juliane Cabral; Almeida, Jackson R G S; de Oliveira, Helinando Pequeno

    2017-01-01

    The development of alternatives for insulin secretion control in vivo or in vitro represents an important aspect to be investigated. In this direction, natural products have been progressively explored with this aim. In particular, flavonoids are potential candidates to act as insulin secretagogue. To study the influence of flavonoid on overall modulation mechanisms of insulin secretion. The research was conducted in the following databases and platforms: PubMed, Scopus, ISI Web of Knowledge, SciELO, LILACS, and ScienceDirect, and the MeSH terms used for the search were flavonoids, flavones, islets of Langerhans, and insulin-secreting cells. Twelve articles were included and represent the basis of discussion on mechanisms of insulin secretion of flavonoids. Papers in ISI Web of Knowledge were in number of 1, Scopus 44, PubMed 264, ScienceDirect 511, and no papers from LILACS and SciELO databases. According to the literature, the majority of flavonoid subclasses can modulate insulin secretion through several pathways, in an indication that corresponding molecule is a potential candidate for active materials to be applied in the treatment of diabetes. The action of natural products on insulin secretion represents an important investigation topic due to their importance in the diabetes controlIn addition to their typical antioxidant properties, flavonoids contribute to the insulin secretionThe modulation of insulin secretion is induced by flavonoids according to different mechanisms. Abbreviations used: K ATP channels: ATP-sensitive K + channels, GLUT4: Glucose transporter 4, ERK1/2: Extracellular signal-regulated protein kinases 1 and 2, L-VDCCs: L-type voltage-dependent Ca +2 channels, GLUT1: Glucose transporter 1, AMPK: Adenosine monophosphate-activated protein kinase, PTP1B: Protein tyrosine phosphatase 1B, GLUT2: Glucose transporter 2, cAMP: Cyclic adenosine monophosphate, PKA: Protein kinase A, PTK: Protein tyrosine kinase, CaMK II: Ca 2+ /calmodulin

  4. The influence of GLP-1 on glucose-stimulated insulin secretion: effects on beta-cell sensitivity in type 2 and nondiabetic subjects

    DEFF Research Database (Denmark)

    Kjems, Lise L; Holst, Jens J; Vølund, Aage

    2003-01-01

    . However, the dose-response relationship between GLP-1 and basal and glucose-stimulated prehepatic insulin secretion rate (ISR) is currently not known. Seven patients with type 2 diabetes and seven matched nondiabetic control subjects were studied. ISR was determined during a graded glucose infusion of 2...

  5. Glucose-stimulated insulin secretion of insulinoma INS-1E cells is associated with elevation of both respiration and mitochondrial membrane potential

    Czech Academy of Sciences Publication Activity Database

    Špaček, Tomáš; Šantorová, Jitka; Zacharovová, K.; Berková, Z.; Hlavatá, Lydie; Saudek, F.; Ježek, Petr

    2008-01-01

    Roč. 40, č. 8 (2008), s. 1522-1535 ISSN 1357-2725 R&D Projects: GA MZd(CZ) NR7917 Institutional research plan: CEZ:AV0Z50110509 Keywords : in situ mitochondrial membrane potential * in situ mitochondrial respiration * glucose-stimulated insulin secretion Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 4.178, year: 2008

  6. Beta-cell specific deletion of Dicer1 leads to defective insulin secretion and diabetes mellitus

    DEFF Research Database (Denmark)

    Kalis, Martins; Bolmeson, Caroline; Esguerra, Jonathan L.S.

    2011-01-01

    -cells specific disruption of the Dicer1 gene using the Cre-lox system controlled by the rat insulin promoter (RIP). In contrast to their normoglycaemic control littermates (RIP-Cre(+/-) Dicer1(¿/wt)), RIP-Cre(+/-)Dicer1(flox/flox) mice (RIP-Cre Dicer1(¿/¿)) developed progressive hyperglycaemia and full...... revealed altered islet morphology, marked decreased ß-cell mass, reduced numbers of granules within the ß-cells and reduced granule docking in adult RIP-Cre Dicer1(¿/¿) mice. ß-cell specific Dicer1 deletion did not appear to disrupt fetal and neonatal ß-cell development as 2-week old RIP-Cre Dicer1...

  7. Transfer plate radioassay using adsorbed anti-insulin antibody to detect insulin secreted by islet cell cultures

    International Nuclear Information System (INIS)

    Scearce, R.M.; Oie, H.K.; Gazdar, A.F.; Chick, W.L.; Eisenbarth, G.S.

    1981-01-01

    A solid-phase radioimmunoassay for detection of insulin synthesized by islet cell clones is described. This assay employs anti-insulin antibody adsorbed onto fenestrated polyvinyl chloride 96-well plates ('transfer plates'). The calibrated aperture in the bottom of each transfer plate well permits fluid to enter the wells when transfer plates are lowered into microculture wells containing insulin. With this assay it is possible to rapidly screen hundreds of islet cell cultures for insulin production. The authors have used this assay to facilitate cloning of the RIN rat insulinoma cell line. The assay readily detects insulin synthesis by RIN cells and [ 125 I]insulin is not displaced by culture medium from cells which do not produce insulin. The transfer plate format should be applicable to semiautomate other radioimmunoassays. (Auth.)

  8. Uncoupling protein 2 regulates daily rhythms of insulin secretion capacity in MIN6 cells and isolated islets from male mice

    Directory of Open Access Journals (Sweden)

    Nivedita Seshadri

    2017-07-01

    Conclusions: Our study suggests that Ucp2/UCP2 in the β cell is part of an important, endogenous, metabolic regulator that controls the temporal capacity of GSIS over the course of the day/night cycle, which, in turn, regulates time-of-day glucose tolerance. Targeting Ucp2/UCP2 as a therapeutic in type 2 diabetes or any other metabolic condition must take into account the rhythmic nature of its expression and its impact on glucose tolerance over 24 h, specifically during the inactive/fasted phase.

  9. Impaired insulin secretion in the spontaneous diabetes rats.

    Science.gov (United States)

    Kimura, K; Toyota, T; Kakizaki, M; Kudo, M; Takebe, K; Goto, Y

    1982-08-01

    Dynamics of insulin and glucagon secretion were investigated by using a new model of spontaneous diabetes rats produced by the repetition of selective breeding in our laboratories. The perfusion experiments of the pancreas showed that the early phase of insulin secretion to continuous stimulation with glucose was specifically impaired, although the response of the early phase to arginine was preserved. The glucose-induced insulin secretion in the nineth generation (F8) which had a more remarkably impaired glucose tolerance was more reduced than in the sixth generation (F5). No significant difference of glucagon secretion in response to arginine or norepinephrine was noted between the diabetes rats and control ones. The present data indicate that the defective insulin secretion is a primary derangement in a diabetic state of the spontaneous diabetes rat. This defect in the early phase of glucose-induced insulin secretion suggests the specific impairment of the recognition of glucose by the pancreatic beta-cells. The spontaneous diabetes rats are very useful as a model of disease for investigating pathophysiology of non-insulin dependent diabetes mellitus.

  10. Co-infusion of autologous adipose tissue derived insulin-secreting mesenchymal stem cells and bone marrow derived hematopoietic stem cells: Viable therapy for type III.C. a diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Umang G Thakkar

    2014-12-01

    Full Text Available Transition from acute pancreatitis to insulin-dependent diabetes mellitus (IDDM is a rare manifestation of primary hyperparathyroidism caused by parathyroid adenoma because of impaired glucose tolerance and suppresses insulin secretion. We report the case of a 26-year-old male with pancreatic diabetes caused by parathyroid adenoma induced chronic pancreatitis. He had serum C-peptide 0.12 ng/ml, glutamic acid decarboxylase antibody 5.0 IU/ml, and glycosylated hemoglobin (HbA1C 8.9%, and required 72 IU/day of biphasic-isophane insulin injection for uncontrolled hyperglycemia. We treated him with his own adipose tissue derived insulin-secreting mesenchymal stem-cells (IS-ADMSC along with his bone marrow derived hematopoietic stem cells (BM-HSC. Autologous IS-ADMSC + BM-HSC were infused into subcutaneous tissue, portal and thymic circulation without any conditioning. Over a follow-up of 27 months, the patient is maintaining fasting and postprandial blood sugar levels of 132 and 165 mg/dl, respectively, with HbA1C 6.8% and requiring 36 IU/day of biphasic-isophane insulin. Co-infusion of IS-ADMSC + BM-HSC offers a safe and viable therapy for type III.C.a Diabetes Mellitus.

  11. H2O2-Activated Mitochondrial Phospholipase iPLA2 gamma Prevents Lipotoxic Oxidative Stress in Synergy with UCP2, Amplifies Signaling via G-Protein-Coupled Receptor GPR40, and Regulates Insulin Secretion in Pancreatic beta-Cells

    Czech Academy of Sciences Publication Activity Database

    Ježek, Jan; Dlasková, Andrea; Zelenka, Jaroslav; Jabůrek, Martin; Ježek, Petr

    2015-01-01

    Roč. 23, č. 12 (2015), s. 958-972 ISSN 1523-0864 R&D Projects: GA ČR(CZ) GPP303/11/P320; GA ČR(CZ) GA13-02033S; GA ČR(CZ) GA13-06666S; GA ČR GA15-02051S Institutional support: RVO:67985823 Keywords : mitochondrial phospholipase iPLA2 gamma * uncoupling protein UCP2 * G-protein coupled receptor - 40 * glucose-stimulated insulin secretion * pancreatic beta cells Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 7.093, year: 2015

  12. Liraglutide, a once-daily human GLP-1 analogue, improves pancreatic B-cell function and arginine-stimulated insulin secretion during hyperglycaemia in patients with Type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Vilsbøll, Tina; Brock, Birgitte; Perrild, Hans

    2008-01-01

    To assess the effect of liraglutide, a once-daily human glucagon-like peptide-1 analogue on pancreatic B-cell function. methods: Patients with Type 2 diabetes (n = 39) were randomized to treatment with 0.65, 1.25 or 1.9 mg/day liraglutide or placebo for 14 weeks. First- and second-phase insulin...... release were measured by means of the insulin-modified frequently sampled intravenous glucose tolerance test. Arginine-stimulated insulin secretion was measured during a hyperglycaemic clamp (20 mmol/l). Glucose effectiveness and insulin sensitivity were estimated by means of the insulin...

  13. Effects of combined calcium and vitamin D supplementation on insulin secretion, insulin sensitivity and β-cell function in multi-ethnic vitamin D-deficient adults at risk for type 2 diabetes: a pilot randomized, placebo-controlled trial.

    Directory of Open Access Journals (Sweden)

    Claudia Gagnon

    Full Text Available To examine whether combined vitamin D and calcium supplementation improves insulin sensitivity, insulin secretion, β-cell function, inflammation and metabolic markers.6-month randomized, placebo-controlled trial.Ninety-five adults with serum 25-hydroxyvitamin D [25(OHD] ≤55 nmol/L at risk of type 2 diabetes (with prediabetes or an AUSDRISK score ≥15 were randomized. Analyses included participants who completed the baseline and final visits (treatment n = 35; placebo n = 45.Daily calcium carbonate (1,200 mg and cholecalciferol [2,000-6,000 IU to target 25(OHD >75 nmol/L] or matching placebos for 6 months.Insulin sensitivity (HOMA2%S, Matsuda index, insulin secretion (insulinogenic index, area under the curve (AUC for C-peptide and β-cell function (Matsuda index x AUC for C-peptide derived from a 75 g 2-h OGTT; anthropometry; blood pressure; lipid profile; hs-CRP; TNF-α; IL-6; adiponectin; total and undercarboxylated osteocalcin.Participants were middle-aged adults (mean age 54 years; 69% Europid at risk of type 2 diabetes (48% with prediabetes. Compliance was >80% for calcium and vitamin D. Mean serum 25(OHD concentration increased from 48 to 95 nmol/L in the treatment group (91% achieved >75 nmol/L, but remained unchanged in controls. There were no significant changes in insulin sensitivity, insulin secretion and β-cell function, or in inflammatory and metabolic markers between or within the groups, before or after adjustment for potential confounders including waist circumference and season of recruitment. In a post hoc analysis restricted to participants with prediabetes, a significant beneficial effect of vitamin D and calcium supplementation on insulin sensitivity (HOMA%S and Matsuda was observed.Daily vitamin D and calcium supplementation for 6 months may not change OGTT-derived measures of insulin sensitivity, insulin secretion and β-cell function in multi-ethnic adults with low vitamin D status at risk of type 2 diabetes

  14. Bridging the Gap Between Protein Carboxyl Methylation and Phospholipid Methylation to Understand Glucose-Stimulated Insulin Secretion From the Pancreatic β Cell

    OpenAIRE

    Kowluru, Anjaneyulu

    2007-01-01

    Recent findings have implicated post-translational modifications at C-terminal cysteines [e.g., methylation] of specific proteins [e.g., G-proteins] in glucose-stimulated insulin secretion [GSIS]. Furthermore, methylation at the C-terminal leucine of the catalytic subunit of protein phosphatase 2A [PP2Ac] has also been shown to be relevant for GSIS. In addition to these two classes of protein methyl transferases, a novel class of glucose-activated phospholipid methyl transferases have also be...

  15. Insulin secretion in lipodystrophic HIV-infected patients is associated with high levels of nonglucose secretagogues and insulin resistance of beta-cells

    DEFF Research Database (Denmark)

    Haugaard, Steen B; Andersen, Ove; Storgaard, Heidi

    2004-01-01

    lipodystrophy (controls). Thirty minutes before start of the clamp, a bolus of glucose was injected intravenously to stimulate endogenous insulin secretion. Insulin sensitivity index (SiRd) was estimated from glucose tracer analysis. LIPO displayed increased basal ISR (69%), clamp ISR (114%), basal insulin (130......, and glucose (all r > 0.41, P triglyceride, and glucagon (all r > 0.51, P triglyceride (r = 0.45, P ...%), and clamp insulin (32%), all P 0.65, P glucose. In control subjects, ISR(basal) correlated significantly with insulin, glucagon...

  16. Impaired insulin secretion and glucose intolerance in synaptotagmin-7 null mutant mice

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Lao, Ye; Maximov, Anton

    2008-01-01

    and insulin release. Here, we show that synaptotagmin-7 is required for the maintenance of systemic glucose tolerance and glucose-stimulated insulin secretion. Mutant mice have normal insulin sensitivity, insulin production, islet architecture and ultrastructural organization, and metabolic and calcium...... secretion in pancreatic beta-cells. Of these other synaptotagmins, synaptotagmin-7 is one of the most abundant and is present in pancreatic beta-cells. To determine whether synaptotagmin-7 regulates Ca(2+)-dependent insulin secretion, we analyzed synaptotagmin-7 null mutant mice for glucose tolerance...... responses but exhibit impaired glucose-induced insulin secretion, indicating a calcium-sensing defect during insulin-containing secretory granule exocytosis. Taken together, our findings show that synaptotagmin-7 functions as a positive regulator of insulin secretion and may serve as a calcium sensor...

  17. Biphasic voltage-dependent inactivation of human NaV 1.3, 1.6 and 1.7 Na+ channels expressed in rodent insulin-secreting cells.

    Science.gov (United States)

    Godazgar, Mahdieh; Zhang, Quan; Chibalina, Margarita V; Rorsman, Patrik

    2018-05-01

    Na + current inactivation is biphasic in insulin-secreting cells, proceeding with two voltage dependences that are half-maximal at ∼-100 mV and -60 mV. Inactivation of voltage-gated Na + (Na V ) channels occurs at ∼30 mV more negative voltages in insulin-secreting Ins1 and primary β-cells than in HEK, CHO or glucagon-secreting αTC1-6 cells. The difference in inactivation between Ins1 and non-β-cells persists in the inside-out patch configuration, discounting an involvement of a diffusible factor. In Ins1 cells and primary β-cells, but not in HEK cells, inactivation of a single Na V subtype is biphasic and follows two voltage dependences separated by 30-40 mV. We propose that Na V channels adopt different inactivation behaviours depending on the local membrane environment. Pancreatic β-cells are equipped with voltage-gated Na + channels that undergo biphasic voltage-dependent steady-state inactivation. A small Na + current component (10-15%) inactivates over physiological membrane potentials and contributes to action potential firing. However, the major Na + channel component is completely inactivated at -90 to -80 mV and is therefore inactive in the β-cell. It has been proposed that the biphasic inactivation reflects the contribution of different Na V α-subunits. We tested this possibility by expression of TTX-resistant variants of the Na V subunits found in β-cells (Na V 1.3, Na V 1.6 and Na V 1.7) in insulin-secreting Ins1 cells and in non-β-cells (including HEK and CHO cells). We found that all Na V subunits inactivated at 20-30 mV more negative membrane potentials in Ins1 cells than in HEK or CHO cells. The more negative inactivation in Ins1 cells does not involve a diffusible intracellular factor because the difference between Ins1 and CHO persisted after excision of the membrane. Na V 1.7 inactivated at 15--20 mV more negative membrane potentials than Na V 1.3 and Na V 1.6 in Ins1 cells but this small difference is insufficient to solely

  18. Evaluation of insulin secretion and action in New World camelids.

    Science.gov (United States)

    Firshman, Anna M; Cebra, Christopher K; Schanbacher, Barbara J; Seaquist, Elizabeth R

    2013-01-01

    To measure and compare insulin secretion and sensitivity in healthy alpacas and llamas via glucose clamping techniques. 8 llamas and 8 alpacas. Hyperinsulinemic euglycemic clamping (HEC) and hyperglycemic clamping (HGC) were performed on each camelid in a crossover design with a minimum 48-hour washout period between clamping procedures. The HEC technique was performed to measure insulin sensitivity. Insulin was infused IV at 6 mU/min/kg for 4 hours, and an IV infusion of glucose was adjusted to maintain blood glucose concentration at 150 mg/dL. Concentrations of blood glucose and plasma insulin were determined throughout. The HGC technique was performed to assess insulin secretion in response to exogenous glucose infusion. An IV infusion of glucose was administered to maintain blood glucose concentration at 320 mg/dL for 3 hours, and concentrations of blood glucose and plasma insulin were determined throughout. Alpacas and llamas were not significantly different with respect to whole-body insulin sensitivity during HEC or in pancreatic β-cell response during HGC. Alpacas and llamas had markedly lower insulin sensitivity during HEC and markedly lower pancreatic β-cell response during HGC, in comparison with many other species. New World camelids had lower glucose-induced insulin secretion and marked insulin resistance in comparison with other species. This likely contributes to the disorders of fat and glucose metabolism that are common to camelids.

  19. The RhoGAP Stard13 controls insulin secretion through F-actin remodeling

    Directory of Open Access Journals (Sweden)

    Heike Naumann

    2018-02-01

    Full Text Available Objective: Actin cytoskeleton remodeling is necessary for glucose-stimulated insulin secretion in pancreatic β-cells. A mechanistic understanding of actin dynamics in the islet is paramount to a better comprehension of β-cell dysfunction in diabetes. Here, we investigate the Rho GTPase regulator Stard13 and its role in F-actin cytoskeleton organization and islet function in adult mice. Methods: We used Lifeact-EGFP transgenic animals to visualize actin cytoskeleton organization and dynamics in vivo in the mouse islets. Furthermore, we applied this model to study actin cytoskeleton and insulin secretion in mutant mice deleted for Stard13 selectively in pancreatic cells. We isolated transgenic islets for 3D-imaging and perifusion studies to measure insulin secretion dynamics. In parallel, we performed histological and morphometric analyses of the pancreas and used in vivo approaches to study glucose metabolism in the mouse. Results: In this study, we provide the first genetic evidence that Stard13 regulates insulin secretion in response to glucose. Postnatally, Stard13 expression became restricted to the mouse pancreatic islets. We showed that Stard13 deletion results in a marked increase in actin polymerization in islet cells, which is accompanied by severe reduction of insulin secretion in perifusion experiments. Consistently, Stard13-deleted mice displayed impaired glucose tolerance and reduced glucose-stimulated insulin secretion. Conclusions: Taken together, our results suggest a previously unappreciated role for the RhoGAP protein Stard13 in the interplay between actin cytoskeletal remodeling and insulin secretion. Keywords: F-actin, Insulin secretion, Islet, Pancreas, Lifeact, Stard13

  20. Blood-based biomarkers of age-associated epigenetic changes in human islets associate with insulin secretion and diabetes

    DEFF Research Database (Denmark)

    Bacos, Karl; Gillberg, Linn; Volkov, Petr

    2016-01-01

    identified in human islets (for example, KLF14, FHL2, ZNF518B and FAM123C) and some associate with insulin secretion and T2D. DNA methylation correlates with islet expression of multiple genes, including FHL2, ZNF518B, GNPNAT1 and HLTF. Silencing these genes in β-cells alter insulin secretion. Together, we...

  1. Mitochondrial metabolism of pyruvate is essential for regulating glucose-stimulated insulin secretion.

    Science.gov (United States)

    Patterson, Jessica N; Cousteils, Katelyn; Lou, Jennifer W; Manning Fox, Jocelyn E; MacDonald, Patrick E; Joseph, Jamie W

    2014-05-09

    It is well known that mitochondrial metabolism of pyruvate is critical for insulin secretion; however, we know little about how pyruvate is transported into mitochondria in β-cells. Part of the reason for this lack of knowledge is that the carrier gene was only discovered in 2012. In the current study, we assess the role of the recently identified carrier in the regulation of insulin secretion. Our studies show that β-cells express both mitochondrial pyruvate carriers (Mpc1 and Mpc2). Using both pharmacological inhibitors and siRNA-mediated knockdown of the MPCs we show that this carrier plays a key role in regulating insulin secretion in clonal 832/13 β-cells as well as rat and human islets. We also show that the MPC is an essential regulator of both the ATP-regulated potassium (KATP) channel-dependent and -independent pathways of insulin secretion. Inhibition of the MPC blocks the glucose-stimulated increase in two key signaling molecules involved in regulating insulin secretion, the ATP/ADP ratio and NADPH/NADP(+) ratio. The MPC also plays a role in in vivo glucose homeostasis as inhibition of MPC by the pharmacological inhibitor α-cyano-β-(1-phenylindol-3-yl)-acrylate (UK5099) resulted in impaired glucose tolerance. These studies clearly show that the newly identified mitochondrial pyruvate carrier sits at an important branching point in nutrient metabolism and that it is an essential regulator of insulin secretion.

  2. Triphenyltin impairs a protein kinase A (PKA)-dependent increase of cytosolic Na+ and Ca2+ and PKA-independent increase of cytosolic Ca2+ associated with insulin secretion in hamster pancreatic β-cells

    International Nuclear Information System (INIS)

    Miura, Yoshikazu; Matsui, Hisao

    2006-01-01

    Oral administration of triphenyltin chloride (TPT) (60 mg/kg body weight) inhibits the insulin secretion by decreasing the cytoplasmic Ca 2+ concentration ([Ca 2+ ] i ) induced by glucose-dependent insulinotropic polypeptide (GIP) in pancreatic β-cells of the hamster. To test the possibility that the abnormal level of [Ca 2+ ] i induced by TPT administration could be due to a defect in the cAMP-dependent cytoplasmic Na + concentration ([Na + ] i ) in the β-cells, we investigated the effects of TPT administration on the changes of [Na + ] i induced by GIP, glucagon-like peptide-1 (GLP-1), or forskolin, an activator of adenylyl cyclase, and on the changes of [Na + ] i or [Ca 2+ ] 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 + ] i and [Ca 2+ ] i were measured in islet cells loaded with sodium-binding benzofuran isophthalate (SBFI) and fura-2, respectively. In the presence of 135 mM Na + , TPT administration significantly reduced the rise in [Na + ] i by 10 nM GLP-1, 10 μM forskolin, and 50 μM 6-Bnz-cAMP, but had not effect in a Na + -free medium. In the presence of 135 mM Na + , TPT administration also reduced the rise in [Ca 2+ ] i by 8-pCPT-2'-O-Me-cAMP plus10 μM 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 2+ response due to a reduced Na + permeability through PKA-dependent mechanisms in hamster islet cells. Also TPT has the reduction of [Ca 2+ ] i related to Na + -dependent insulin secretion after an activation of Epac

  3. Factors influencing insulin secretion from encapsulated islets

    NARCIS (Netherlands)

    de Haan, BJ; Faas, MM; de Vos, P

    2003-01-01

    Adequate regulation of glucose levels by a microencapsulated pancreatic islet graft requires a minute-to-minute regulation of blood glucose. To design such a transplant, it is mandatory to have sufficient insight in factors influencing the kinetics of insulin secretion by encapsulated islets. The

  4. Butanol fraction of Parkia biglobosa (Jacq.) G. Don leaves enhance pancreatic β-cell functions, stimulates insulin secretion and ameliorates other type 2 diabetes-associated complications in rats.

    Science.gov (United States)

    Ibrahim, Mohammed Auwal; Habila, James Dama; Koorbanally, Neil Anthony; Islam, Md Shahidul

    2016-05-13

    Ethnopharmacological surveys have reported that Parkia biglobosa (Jacq.) G. Don (Leguminosae) is among the plants commonly used in the traditional management of diabetes mellitus in Nigeria and Togo. This study investigated the anti-diabetic activity of the butanol fraction of P. biglobosa leaves (PBBF) in a type 2 diabetes (T2D) model of rats and a possible bioactive compound in the fraction. T2D was induced by feeding rats with a 10% fructose solution ad libitum for two weeks followed by an intraperitoneal injection of 40mg/kg body weight streptozotocin and the animals were orally treated with 150 and 300mg/kg BW of the PBBF for five days in a week. Another group of rats was non-diabetic but similarly administered with 300mg/kg BW of the PBBF. Food and fluid intakes, body weight changes and blood glucose levels were monitored during the experiment while other relevant diabetes-associated parameters were measured at the end of the experiment. The PBBF treatments significantly (P<0.05) decreased the blood glucose levels and improved the glucose tolerance ability compared to untreated diabetic rats. Furthermore, the treatments were found to improve pancreatic β cell function (HOMA-β), stimulate insulin secretions, decrease insulin resistance (HOMA-IR), restore liver glycogen, ameliorate serum dyslipidaemia and prevent hepatic and renal damages compared to untreated diabetic rats. Phytochemical analysis of the fraction led to the isolation of lupeol which inhibited α-glucosidase and α-amylase in non-competitive and uncompetitive inhibition patterns respectively. It was concluded that PBBF possessed remarkable anti-T2D activity which is mediated through modulation of β-cell function and stimulation of insulin secretion and the lower dose (150mg/kg BW) was found optimum for anti-T2D activity compared to the high dose (300mg/kg BW) in this study. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. In vitro expansion and differentiation of rat pancreatic duct-derived stem cells into insulin secreting cells using a dynamicthree-dimensional cell culture system.

    Science.gov (United States)

    Chen, X C; Liu, H; Li, H; Cheng, Y; Yang, L; Liu, Y F

    2016-06-27

    In this study, a dynamic three-dimensional cell culture technology was used to expand and differentiate rat pancreatic duct-derived stem cells (PDSCs) into islet-like cell clusters that can secrete insulin. PDSCs were isolated from rat pancreatic tissues by in situ collagenase digestion and density gradient centrifugation. Using a dynamic three-dimensional culture technique, the cells were expanded and differentiated into functional islet-like cell clusters, which were characterized by morphological and phenotype analyses. After maintaining 1 x 108 isolated rat PDSCs in a dynamic three-dimensional cell culture for 7 days, 1.5 x 109 cells could be harvested. Passaged PDSCs expressed markers of pancreatic endocrine progenitors, including CD29 (86.17%), CD73 (90.73%), CD90 (84.13%), CD105 (78.28%), and Pdx-1. Following 14 additional days of culture in serum-free medium with nicotinamide, keratinocyte growth factor (KGF), and b fibroblast growth factor (FGF), the cells were differentiated into islet-like cell clusters (ICCs). The ICC morphology reflected that of fused cell clusters. During the late stage of differentiation, representative clusters were non-adherent and expressed insulin indicated by dithizone (DTZ)-positive staining. Insulin was detected in the extracellular fluid and cytoplasm of ICCs after 14 days of differentiation. Additionally, insulin levels were significantly higher at this time compared with the levels exhibited by PDSCs before differentiation (P cell culture system, PDSCs can be expanded in vitro and can differentiate into functional islet-like cell clusters.

  6. An ancestral role for the mitochondrial pyruvate carrier in glucose-stimulated insulin secretion

    Directory of Open Access Journals (Sweden)

    Kyle S. McCommis

    2016-08-01

    Full Text Available Objective: Transport of pyruvate into the mitochondrial matrix by the Mitochondrial Pyruvate Carrier (MPC is an important and rate-limiting step in its metabolism. In pancreatic β-cells, mitochondrial pyruvate metabolism is thought to be important for glucose sensing and glucose-stimulated insulin secretion. Methods: To evaluate the role that the MPC plays in maintaining systemic glucose homeostasis, we used genetically-engineered Drosophila and mice with loss of MPC activity in insulin-producing cells. Results: In both species, MPC deficiency results in elevated blood sugar concentrations and glucose intolerance accompanied by impaired glucose-stimulated insulin secretion. In mouse islets, β-cell MPC-deficiency resulted in decreased respiration with glucose, ATP-sensitive potassium (KATP channel hyperactivity, and impaired insulin release. Moreover, treatment of pancreas-specific MPC knockout mice with glibenclamide, a sulfonylurea KATP channel inhibitor, improved defects in islet insulin secretion and abnormalities in glucose homeostasis in vivo. Finally, using a recently-developed biosensor for MPC activity, we show that the MPC is rapidly stimulated by glucose treatment in INS-1 insulinoma cells suggesting that glucose sensing is coupled to mitochondrial pyruvate carrier activity. Conclusions: Altogether, these studies suggest that the MPC plays an important and ancestral role in insulin-secreting cells in mediating glucose sensing, regulating insulin secretion, and controlling systemic glycemia. Keywords: Stimulus-coupled secretion, Insulin, β-Cell, Diabetes, Pyruvate, Mitochondria, Drosophila

  7. Mitochondrial GTP Regulates Glucose-Induced Insulin Secretion

    OpenAIRE

    Kibbey, Richard G.; Pongratz, Rebecca L.; Romanelli, Anthony J.; Wollheim, Claes B.; Cline, Gary W.; Shulman, Gerald I.

    2007-01-01

    Substrate-level mitochondrial GTP (mtGTP) and ATP (mtATP) synthesis occurs by nucleotide-specific isoforms of the tricarboxylic acid (TCA) cycle enzyme succinyl CoA synthetase (SCS). Unlike mtATP, each molecule of glucose metabolized produces approximately one mtGTP in pancreatic β-cells independent of coupling with oxidative phosphorylation making mtGTP a potentially important fuel signal. siRNA suppression of the GTP-producing pathway (ΔSCS-GTP) reduced glucose-stimulated insulin secretion ...

  8. Insulin secretion and sensitivity in space flight: diabetogenic effects

    Science.gov (United States)

    Tobin, Brian W.; Uchakin, Peter N.; Leeper-Woodford, Sandra K.

    2002-01-01

    Nearly three decades of space flight research have suggested that there are subclinical diabetogenic changes that occur in microgravity. Alterations in insulin secretion, insulin sensitivity, glucose tolerance, and metabolism of protein and amino acids support the hypothesis that insulin plays an essential role in the maintenance of muscle mass in extended-duration space flight. Experiments in flight and after flight and ground-based bedrest studies have associated microgravity and its experimental paradigms with manifestations similar to those of diabetes, physical inactivity, and aging. We propose that these manifestations are characterized best by an etiology that falls into the clinical category of "other" causes of diabetes, including, but not restricted to, genetic beta-cell defects, insulin action defects, diseases of the endocrine pancreas, endocrinopathies, drug or chemically induced diabetes, infections, immune-mediated metabolic alteration, and a host of genetic related diseases. We present data showing alterations in tumor necrosis factor-alpha production, insulin secretion, and amino acid metabolism in pancreatic islets of Langerhans cultured in a ground-based cell culture bioreactor that mimics some of the effects of microgravity. Taken together, space flight research, ground-based studies, and bioreactor studies of pancreatic islets of Langerhans support the hypothesis that the pancreas is unable to overcome peripheral insulin resistance and amino acid dysregulation during space flight. We propose that measures of insulin secretion and insulin action will be necessary to design effective countermeasures against muscle loss, and we advance the "disposition index" as an essential model to be used in the clinical management of space flight-induced muscle loss.

  9. Insulin secretion and insulin resistance in Korean women with gestational diabetes mellitus and impaired glucose tolerance.

    Science.gov (United States)

    Yang, Sae Jeong; Kim, Tae Nyun; Baik, Sei Hyun; Kim, Tae Sun; Lee, Kwan Woo; Nam, Moonsuk; Park, Yong Soo; Woo, Jeong-Teak; Kim, Young Seol; Kim, Sung-Hoon

    2013-05-01

    The aim was to compare the insulin sensitivity and secretion index of pregnant Korean women with normal glucose tolerance (NGT), gestational impaired glucose tolerance (GIGT; only one abnormal value according to the Carpenter and Coustan criteria), and gestational diabetes mellitus (GDM). A cross-sectional study was performed with 1,163 pregnant women with positive (1-hour plasma glucose ≥ 7.2 mmol/L) in a 50-g oral glucose challenge test (OGCT). The 100-g oral glucose tolerance test (OGTT) was used to stratify the participants into three groups: NGT (n = 588), GIGT (n = 294), and GDM (n = 281). The GDM group had higher homeostasis model assessment of insulin resistance and lower insulin sensitivity index (ISOGTT), quantitative insulin sensitivity check index, homeostasis model assessment for estimation of index β-cell secretion (HOMA-B), first and second phase insulin secretion, and insulin secretion-sensitivity index (ISSI) than the NGT group (p ≤ 0.001 for all). Moreover, the GIGT group had lower ISOGTT, HOMA-B, first and second phase insulin secretion, and ISSI than the NGT group (p insulin secretion status than the 3-hour abnormal levels group. Korean women with GDM show impairments of both insulin secretion and insulin sensitivity. In addition, GIGT is associated with both β-cell dysfunction and insulin resistance.

  10. Mitochondrial GTP Regulates Glucose-Induced Insulin Secretion

    Science.gov (United States)

    Kibbey, Richard G.; Pongratz, Rebecca L.; Romanelli, Anthony J.; Wollheim, Claes B.; Cline, Gary W.; Shulman, Gerald I.

    2007-01-01

    Summary Substrate-level mitochondrial GTP (mtGTP) and ATP (mtATP) synthesis occurs by nucleotide-specific isoforms of the tricarboxylic acid (TCA) cycle enzyme succinyl CoA synthetase (SCS). Unlike mtATP, each molecule of glucose metabolized produces approximately one mtGTP in pancreatic β-cells independent of coupling with oxidative phosphorylation making mtGTP a potentially important fuel signal. siRNA suppression of the GTP-producing pathway (ΔSCS-GTP) reduced glucose-stimulated insulin secretion (GSIS) by 50%, whereas suppression of the parallel ATP-producing isoform (ΔSCS-ATP) increased GSIS by two-fold in INS-1 832/13 cells and cultured rat islets. Insulin secretion correlated with increases in cytosolic calcium but not with changes in NAD(P)H or the ATP/ADP ratio. These data suggest an important role for mtGTP in mediating GSIS in β-cells by modulation of mitochondrial metabolism possibly via influencing mitochondrial calcium. Furthermore, by virtue of its tight coupling to TCA oxidation rates, mtGTP production may serve as an important molecular signal of TCA cycle activity. PMID:17403370

  11. Depressive symptoms, insulin sensitivity and insulin secretion in the RISC cohort study

    DEFF Research Database (Denmark)

    Bot, M; Pouwer, F; De Jonge, P

    2013-01-01

    Sensitivity and Cardiovascular Disease Risk (RISC) study. Presence of significant depressive symptoms was defined as a Center for Epidemiologic Studies Depression Scale (CES-D) score ≥ 16. Standard oral glucose tolerance tests were performed. Insulin sensitivity was assessed with the oral glucose insulin......AIM: This study explored the association of depressive symptoms with indices of insulin sensitivity and insulin secretion in a cohort of non-diabetic men and women aged 30 to 64 years. METHODS: The study population was derived from the 3-year follow-up of the Relationship between Insulin...... sensitivity (OGIS) index. Insulin secretion was estimated using three model-based parameters of insulin secretion (beta-cell glucose sensitivity, the potentiation factor ratio, and beta-cell rate sensitivity). RESULTS: A total of 162 out of 1027 participants (16%) had significant depressive symptoms. Having...

  12. The zinc transporter ZNT3 co-localizes with insulin in INS-1E pancreatic beta cells and influences cell survival, insulin secretion capacity, and ZNT8 expression

    DEFF Research Database (Denmark)

    Smidt, Kamille; Larsen, Agnete; Brønden, Andreas

    2016-01-01

    Zinc trafficking in pancreatic beta cells is tightly regulated by zinc transporting (ZNTs) proteins. The role of different ZNTs in the beta cells is currently being clarified. ZNT8 transports zinc into insulin granules and is critical for a correct insulin crystallization and storage in the granu......Zinc trafficking in pancreatic beta cells is tightly regulated by zinc transporting (ZNTs) proteins. The role of different ZNTs in the beta cells is currently being clarified. ZNT8 transports zinc into insulin granules and is critical for a correct insulin crystallization and storage...

  13. Closing in on the Mechanisms of Pulsatile Insulin Secretion.

    Science.gov (United States)

    Bertram, Richard; Satin, Leslie S; Sherman, Arthur S

    2018-03-01

    Insulin secretion from pancreatic islet β-cells occurs in a pulsatile fashion, with a typical period of ∼5 min. The basis of this pulsatility in mouse islets has been investigated for more than four decades, and the various theories have been described as either qualitative or mathematical models. In many cases the models differ in their mechanisms for rhythmogenesis, as well as other less important details. In this Perspective, we describe two main classes of models: those in which oscillations in the intracellular Ca 2+ concentration drive oscillations in metabolism, and those in which intrinsic metabolic oscillations drive oscillations in Ca 2+ concentration and electrical activity. We then discuss nine canonical experimental findings that provide key insights into the mechanism of islet oscillations and list the models that can account for each finding. Finally, we describe a new model that integrates features from multiple earlier models and is thus called the Integrated Oscillator Model. In this model, intracellular Ca 2+ acts on the glycolytic pathway in the generation of oscillations, and it is thus a hybrid of the two main classes of models. It alone among models proposed to date can explain all nine key experimental findings, and it serves as a good starting point for future studies of pulsatile insulin secretion from human islets. © 2018 by the American Diabetes Association.

  14. CRFR1 is expressed on pancreatic beta cells, promotes beta cell proliferation, and potentiates insulin secretion in a glucose-dependent manner

    DEFF Research Database (Denmark)

    Huising, Mark O; van der Meulen, Talitha; Vaughan, Joan M

    2009-01-01

    Corticotropin-releasing factor (CRF), originally characterized as the principal neuroregulator of the hypothalamus-pituitary-adrenal axis, has broad central and peripheral distribution and actions. We demonstrate the presence of CRF receptor type 1 (CRFR1) on primary beta cells and show that acti...

  15. Radioimmunologic study of insulin secretion during acute radiation sickness

    International Nuclear Information System (INIS)

    Barkalaya, A.I.

    1977-01-01

    Insulin secretion in irradiated (750 R) albino rats has been studied radioimmunologically. The data obtained were correlated with the corticosterone and glucose contents of blood. It has been shown that there is a risk of relative incompetence of insulin secretion during the hypercorticoidism and hyperglycemia

  16. Radioimmunologic study of insulin secretion during acute radiation sickness

    Energy Technology Data Exchange (ETDEWEB)

    Barkalaya, A I

    1977-01-01

    Insulin secretion in irradiated (750 R) albino rats has been studied radioimmunologically. The data obtained were correlated with the corticosterone and glucose contents of blood. It has been shown that there is a risk of relative incompetence of insulin secretion during the hypercorticoidism and hyperglycemia.

  17. CNC-bZIP protein Nrf1-dependent regulation of glucose-stimulated insulin secretion.

    Science.gov (United States)

    Zheng, Hongzhi; Fu, Jingqi; Xue, Peng; Zhao, Rui; Dong, Jian; Liu, Dianxin; Yamamoto, Masayuki; Tong, Qingchun; Teng, Weiping; Qu, Weidong; Zhang, Qiang; Andersen, Melvin E; Pi, Jingbo

    2015-04-01

    The inability of pancreatic β-cells to secrete sufficient insulin in response to glucose stimulation is a major contributing factor to the development of type 2 diabetes (T2D). We investigated both the in vitro and in vivo effects of deficiency of nuclear factor-erythroid 2-related factor 1 (Nrf1) in β-cells on β-cell function and glucose homeostasis. Silencing of Nrf1 in β-cells leads to a pre-T2D phenotype with disrupted glucose metabolism and impaired insulin secretion. Specifically, MIN6 β-cells with stable knockdown of Nrf1 (Nrf1-KD) and isolated islets from β-cell-specific Nrf1-knockout [Nrf1(b)-KO] mice displayed impaired glucose responsiveness, including elevated basal insulin release and decreased glucose-stimulated insulin secretion (GSIS). Nrf1(b)-KO mice exhibited severe fasting hyperinsulinemia, reduced GSIS, and glucose intolerance. Silencing of Nrf1 in MIN6 cells resulted in oxidative stress and altered glucose metabolism, with increases in both glucose uptake and aerobic glycolysis, which is associated with the elevated basal insulin release and reduced glucose responsiveness. The elevated glycolysis and reduced glucose responsiveness due to Nrf1 silencing likely result from altered expression of glucose metabolic enzymes, with induction of high-affinity hexokinase 1 and suppression of low-affinity glucokinase. Our study demonstrated a novel role of Nrf1 in regulating glucose metabolism and insulin secretion in β-cells and characterized Nrf1 as a key transcription factor that regulates the coupling of glycolysis and mitochondrial metabolism and GSIS. Nrf1 plays critical roles in regulating glucose metabolism, mitochondrial function, and insulin secretion, suggesting that Nrf1 may be a novel target to improve the function of insulin-secreting β-cells.

  18. Adverse effects of reduced oxygen tension on the proliferative capacity of rat kidney and insulin-secreting cell lines involve DNA damage and stress responses

    International Nuclear Information System (INIS)

    Chen Jianhua; Jones, R. Huw; Tarry-Adkins, Jane; Smith, Noel H.; Ozanne, Susan E.

    2008-01-01

    Standard cell culture conditions do not reflect the physiological environment in terms of oxygen tension (20% vs 3%). The effects of lowering oxygen tension on cell proliferation in culture can be beneficial as well as detrimental depending on the cell line studied, but the molecular mechanism underlying such effects is not fully understood. We observed that the proliferative capacity of the rat cell lines NRK and INS-1 was inhibited when cultured under 3% oxygen as compared to 20% oxygen. Suppression of proliferation in NRK cells was accompanied by induction of DNA double strand breaks whereas in INS-1 cells it was accompanied by up-regulation of p53 and p27. Although Sirt1 was up-regulated in both cell lines by 3% oxygen the effects on antioxidant enzymes (MnSOD, CuZnSOD and catalase) were cell line specific. Marked up-regulation of heme oxygenase-1 (HO-1) was detected in both NRK and INS-1 cells when cultured in 3% oxygen. HO-1 expression can be readily induced by exposure to hydrogen peroxide in culture. These results suggest that reduced oxygen tension suppresses the proliferative capacity of these two cell lines through a stress response that is similar to an oxidative stress response but the molecular events that lead to the reduced cell proliferation are cell line specific

  19. Acute stimulation of brain mu opioid receptors inhibits glucose-stimulated insulin secretion via sympathetic innervation.

    Science.gov (United States)

    Tudurí, Eva; Beiroa, Daniel; Stegbauer, Johannes; Fernø, Johan; López, Miguel; Diéguez, Carlos; Nogueiras, Rubén

    2016-11-01

    Pancreatic insulin-secreting β-cells express opioid receptors, whose activation by opioid peptides modulates hormone secretion. Opioid receptors are also expressed in multiple brain regions including the hypothalamus, where they play a role in feeding behavior and energy homeostasis, but their potential role in central regulation of glucose metabolism is unknown. Here, we investigate whether central opioid receptors participate in the regulation of insulin secretion and glucose homeostasis in vivo. C57BL/6J mice were acutely treated by intracerebroventricular (i.c.v.) injection with specific agonists for the three main opioid receptors, kappa (KOR), delta (DOR) and mu (MOR) opioid receptors: activation of KOR and DOR did not alter glucose tolerance, whereas activation of brain MOR with the specific agonist DAMGO blunted glucose-stimulated insulin secretion (GSIS), reduced insulin sensitivity, increased the expression of gluconeogenic genes in the liver and, consequently, impaired glucose tolerance. Pharmacological blockade of α2A-adrenergic receptors prevented DAMGO-induced glucose intolerance and gluconeogenesis. Accordingly, DAMGO failed to inhibit GSIS and to impair glucose tolerance in α2A-adrenoceptor knockout mice, indicating that the effects of central MOR activation on β-cells are mediated via sympathetic innervation. Our results show for the first time a new role of the central opioid system, specifically the MOR, in the regulation of insulin secretion and glucose metabolism. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Insulin secretion and action in North Indian women during pregnancy.

    Science.gov (United States)

    Arora, G P; Almgren, P; Thaman, R G; Pal, A; Groop, L; Vaag, A; Prasad, R B; Brøns, C

    2017-10-01

    The relative roles(s) of impaired insulin secretion vs. insulin resistance in the development of gestational diabetes mellitus depend upon multiple risk factors and diagnostic criteria. Here, we explored their relative contribution to gestational diabetes as defined by the WHO 1999 (GDM1999) and adapted WHO 2013 (GDM2013) criteria, excluding the 1-h glucose value, in a high-risk Indian population from Punjab. Insulin secretion (HOMA2-B) and insulin action (HOMA2-IR) were assessed in 4665 Indian women with or without gestational diabetes defined by the GDM1999 or adapted GDM2013 criteria. Gestational diabetes defined using both criteria was associated with decreased insulin secretion compared with pregnant women with normal glucose tolerance. Women with gestational diabetes defined by the adapted GDM2013, but not GDM1999 criteria, were more insulin resistant than pregnant women with normal glucose tolerance, and furthermore displayed lower insulin secretion than GDM1999 women. Urban habitat, illiteracy, high age and low BMI were independently associated with reduced insulin secretion, whereas Sikh religion, increasing age and BMI, as well as a family history of diabetes were independently associated with increased insulin resistance. Gestational diabetes risk factors influence insulin secretion and action in North Indian women in a differential manner. Gestational diabetes classified using the adapted GDM2013 compared with GDM1999 criteria is associated with more severe impairments of insulin secretion and action. © 2017 Diabetes UK.

  1. Saponins from the traditional medicinal plant Momordica charantia stimulate insulin secretion in vitro

    Science.gov (United States)

    Keller, Amy C.; Ma, Jun; Kavalier, Adam; He, Kan; Brillantes, Anne-Marie B.; Kennelly, Edward J.

    2012-01-01

    The antidiabetic activity of Momordica charantia (L.), Cucurbitaceae, a widely-used treatment for diabetes in a number of traditional medicine systems, was investigated in vitro. Antidiabetic activity has been reported for certain saponins isolated from M. charantia. In this study insulin secretion was measured in MIN6 β-cells incubated with an ethanol extract, saponin-rich fraction, and five purified saponins and cucurbitane triterpenoids from M. charantia, 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al (1), momordicine I (2), momordicine II (3), 3-hydroxycucurbita-5,24-dien-19-al-7,23-di-O-β-glucopyranoside (4), and kuguaglycoside G (5). Treatments were compared to incubation with high glucose (27 mM) and the insulin secretagogue, glipizide (50 μM). At 125 μg/ml, an LC-ToF-MS characterized saponin-rich fraction stimulated insulin secretion significantly more than the DMSO vehicle, p=0.02. At concentrations 10 and 25 μg/ml, compounds 3 and 5 also significantly stimulated insulin secretion as compared to the vehicle, p≤0.007, and p= 0.002, respectively. This is the first report of a saponin-rich fraction, and isolated compounds from M. charantia, stimulating insulin secretion in an in vitro, static incubation assay. PMID:22133295

  2. Reproducible insulin secretion from isolated rat pancreas preparations using an organ bath.

    Science.gov (United States)

    Morita, Asuka; Ouchi, Motoshi; Terada, Misao; Kon, Hiroe; Kishimoto, Satoko; Satoh, Keitaro; Otani, Naoyuki; Hayashi, Keitaro; Fujita, Tomoe; Inoue, Ken-Ichi; Anzai, Naohiko

    2018-02-09

    Diabetes mellitus is a lifestyle-related disease that is characterized by inappropriate or diminished insulin secretion. Ex vivo pharmacological studies of hypoglycemic agents are often conducted using perfused pancreatic preparations. Pancreas preparations for organ bath experiments do not require cannulation and are therefore less complex than isolated perfused pancreas preparations. However, previous research has generated almost no data on insulin secretion from pancreas preparations using organ bath preparations. The purpose of this study was to investigate the applicability of isolated rat pancreas preparations using the organ bath technique in the quantitative analysis of insulin secretion from β-cells. We found that insulin secretion significantly declined during incubation in the organ bath, whereas it was maintained in the presence of 1 µM GLP-1. Conversely, amylase secretion exhibited a modest increase during incubation and was not altered in the presence of GLP-1. These results demonstrate that the pancreatic organ bath preparation is a sensitive and reproducible method for the ex vivo assessment of the pharmacological properties of hypoglycemic agents.

  3. Gliadin Fragments and a Specific Gliadin 33-mer Peptide Close KATP Channels and Induce Insulin Secretion in INS-1E Cells and Rat Islets of Langerhans

    DEFF Research Database (Denmark)

    Dall, Morten; Calloe, Kirstine; Haupt-Jorgensen, Martin

    2013-01-01

    . A similar effect was observed in isolated rat islets (1.6-fold increase). In INS-1E cells, diazoxide reduced the stimulatory effect of gliadin digest. Additionally, gliadin digest was shown to decrease current through KATP-channels. A specific gliadin 33-mer had a similar effect, both on current and insulin...

  4. Differences in beta-cell function and insulin secretion in Black vs. White obese adolescents: Do incretin hormones play a role?

    Science.gov (United States)

    Black youth are at higher risk for type 2 diabetes (T2D) than their White peers. Previously we demonstrated that for the same degree of insulin sensitivity, Black youth have an upregulated beta-cell function and insulin hypersecretion, in response to intravenous (IV) glucose, compared with Whites. T...

  5. [6]-Gingerol, from Zingiber officinale, potentiates GLP-1 mediated glucose-stimulated insulin secretion pathway in pancreatic β-cells and increases RAB8/RAB10-regulated membrane presentation of GLUT4 transporters in skeletal muscle to improve hyperglycemia in Leprdb/db type 2 diabetic mice.

    Science.gov (United States)

    Samad, Mehdi Bin; Mohsin, Md Nurul Absar Bin; Razu, Bodiul Alam; Hossain, Mohammad Tashnim; Mahzabeen, Sinayat; Unnoor, Naziat; Muna, Ishrat Aklima; Akhter, Farjana; Kabir, Ashraf Ul; Hannan, J M A

    2017-08-09

    [6]-Gingerol, a major component of Zingiber officinale, was previously reported to ameliorate hyperglycemia in type 2 diabetic mice. Endocrine signaling is involved in insulin secretion and is perturbed in db/db Type-2 diabetic mice. [6]-Gingerol was reported to restore the disrupted endocrine signaling in rodents. In this current study on Lepr db/db diabetic mice, we investigated the involvement of endocrine pathway in the insulin secretagogue activity of [6]-Gingerol and the mechanism(s) through which [6]-Gingerol ameliorates hyperglycemia. Lepr db/db type 2 diabetic mice were orally administered a daily dose of [6]-Gingerol (200 mg/kg) for 28 days. We measured the plasma levels of different endocrine hormones in fasting and fed conditions. GLP-1 levels were modulated using pharmacological approaches, and cAMP/PKA pathway for insulin secretion was assessed by qRT-PCR and ELISA in isolated pancreatic islets. Total skeletal muscle and its membrane fractions were used to measure glycogen synthase 1 level and Glut4 expression and protein levels. 4-weeks treatment of [6]-Gingerol dramatically increased glucose-stimulated insulin secretion and improved glucose tolerance. Plasma GLP-1 was found to be significantly elevated in the treated mice. Pharmacological intervention of GLP-1 levels regulated the effect of [6]-Gingerol on insulin secretion. Mechanistically, [6]-Gingerol treatment upregulated and activated cAMP, PKA, and CREB in the pancreatic islets, which are critical components of GLP-1-mediated insulin secretion pathway. [6]-Gingerol upregulated both Rab27a GTPase and its effector protein Slp4-a expression in isolated islets, which regulates the exocytosis of insulin-containing dense-core granules. [6]-Gingerol treatment improved skeletal glycogen storage by increased glycogen synthase 1 activity. Additionally, GLUT4 transporters were highly abundant in the membrane of the skeletal myocytes, which could be explained by the increased expression of Rab8 and Rab

  6. Effect of alcohol on insulin secretion and viability of human pancreatic islets

    Directory of Open Access Journals (Sweden)

    Nikolić Dragan

    2017-01-01

    Full Text Available Introduction/Objective. There are controversial data in the literature on the topic of effects of alcohol on insulin secretion, apoptosis, and necrosis of the endocrine and exocrine pancreas. The goal of this research was to determine how alcohol affects the insulin secretion and viability of human adult pancreatic islets in vitro during a seven-day incubation. Methods. Human pancreatic tissue was digested with Collagenase XI, using a non-automated method. Cultures were incubated in Roswell Park Memorial Institute (RPMI medium containing alcohol (10 μl of alcohol in 100 ml of medium. Insulin stimulation index (SI and viability of the islets were determined on the first, third, and seventh day of cultivation. Results. Analysis of the viability of the islets showed that there wasn’t significant difference between the control and the test group. In the test group, viability of the cultures declined with the time of incubation. SI of the test group was higher compared to the control group, by 50% and 25% on the first and third day of cultivation, respectively. On the seventh day, insulin secretion was reduced by 25%. The difference was not statistically significant (p > 0.05. In the test group, significant decline in insulin secretion was found on the third and seventh day of incubation (p ≤ 0.05. Conclusion. Alcohol can increase or decrease insulin secretion of islets cultures, which may result in an inadequate response of pancreatic β-cells to blood glucose, leading to insulin resistance, and increased risk of developing type 2 diabetes. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 41002

  7. effect of low glycaemic index meals on insulin secretion

    African Journals Online (AJOL)

    DR. AMINU

    2012-12-02

    Dec 2, 2012 ... Chicago, IL, USA). Data was presented as mean plus .... carbohydrate along a longer portion of the small intestine ... insulin secretion despite producing relatively small .... Laaksonen, D E, Lindström, J, Lakka, T.A, Eriksson,.

  8. Molecular Mechanisms of Insulin Secretion and Insulin Action.

    Science.gov (United States)

    Flatt, Peter R.; Bailey, Clifford J.

    1991-01-01

    Information and current ideas on the factors regulating insulin secretion, the mechanisms underlying the secretion and biological actions of insulin, and the main characteristics of diabetes mellitus are presented. (Author)

  9. Integrative network analysis highlights biological processes underlying GLP-1 stimulated insulin secretion: A DIRECT study.

    Directory of Open Access Journals (Sweden)

    Valborg Gudmundsdottir

    Full Text Available Glucagon-like peptide 1 (GLP-1 stimulated insulin secretion has a considerable heritable component as estimated from twin studies, yet few genetic variants influencing this phenotype have been identified. We performed the first genome-wide association study (GWAS of GLP-1 stimulated insulin secretion in non-diabetic individuals from the Netherlands Twin register (n = 126. This GWAS was enhanced using a tissue-specific protein-protein interaction network approach. We identified a beta-cell protein-protein interaction module that was significantly enriched for low gene scores based on the GWAS P-values and found support at the network level in an independent cohort from Tübingen, Germany (n = 100. Additionally, a polygenic risk score based on SNPs prioritized from the network was associated (P < 0.05 with glucose-stimulated insulin secretion phenotypes in up to 5,318 individuals in MAGIC cohorts. The network contains both known and novel genes in the context of insulin secretion and is enriched for members of the focal adhesion, extracellular-matrix receptor interaction, actin cytoskeleton regulation, Rap1 and PI3K-Akt signaling pathways. Adipose tissue is, like the beta-cell, one of the target tissues of GLP-1 and we thus hypothesized that similar networks might be functional in both tissues. In order to verify peripheral effects of GLP-1 stimulation, we compared the transcriptome profiling of ob/ob mice treated with liraglutide, a clinically used GLP-1 receptor agonist, versus baseline controls. Some of the upstream regulators of differentially expressed genes in the white adipose tissue of ob/ob mice were also detected in the human beta-cell network of genes associated with GLP-1 stimulated insulin secretion. The findings provide biological insight into the mechanisms through which the effects of GLP-1 may be modulated and highlight a potential role of the beta-cell expressed genes RYR2, GDI2, KIAA0232, COL4A1 and COL4A2 in GLP-1 stimulated

  10. Reactive oxygen species as a signal in glucose-stimulated insulin secretion.

    Science.gov (United States)

    Pi, Jingbo; Bai, Yushi; Zhang, Qiang; Wong, Victoria; Floering, Lisa M; Daniel, Kiefer; Reece, Jeffrey M; Deeney, Jude T; Andersen, Melvin E; Corkey, Barbara E; Collins, Sheila

    2007-07-01

    One of the unique features of beta-cells is their relatively low expression of many antioxidant enzymes. This could render beta-cells susceptible to oxidative damage but may also provide a system that is sensitive to reactive oxygen species as signals. In isolated mouse islets and INS-1(832/13) cells, glucose increases intracellular accumulation of H2O2. In both models, insulin secretion could be stimulated by provision of either exogenous H2O2 or diethyl maleate, which raises intracellular H2O2 levels. Provision of exogenous H2O2 scavengers, including cell permeable catalase and N-acetyl-L-cysteine, inhibited glucose-stimulated H2O2 accumulation and insulin secretion (GSIS). In contrast, cell permeable superoxide dismutase, which metabolizes superoxide into H2O2, had no effect on GSIS. Because oxidative stress is an important risk factor for beta-cell dysfunction in diabetes, the relationship between glucose-induced H2O2 generation and GSIS was investigated under various oxidative stress conditions. Acute exposure of isolated mouse islets or INS-1(832/13) cells to oxidative stressors, including arsenite, 4-hydroxynonenal, and methylglyoxal, led to decreased GSIS. This impaired GSIS was associated with increases in a battery of endogenous antioxidant enzymes. Taken together, these findings suggest that H2O2 derived from glucose metabolism is one of the metabolic signals for insulin secretion, whereas oxidative stress may disturb its signaling function.

  11. Hormone-sensitive lipase deficiency suppresses insulin secretion from pancreatic islets of Lepob/ob mice

    International Nuclear Information System (INIS)

    Sekiya, Motohiro; Yahagi, Naoya; Tamura, Yoshiaki; Okazaki, Hiroaki; Igarashi, Masaki; Ohta, Keisuke; Takanashi, Mikio; Kumagai, Masayoshi; Takase, Satoru; Nishi, Makiko; Takeuchi, Yoshinori; Izumida, Yoshihiko; Kubota, Midori; Ohashi, Ken; Iizuka, Yoko; Yagyu, Hiroaki; Gotoda, Takanari; Nagai, Ryozo; Shimano, Hitoshi; Yamada, Nobuhiro

    2009-01-01

    It has long been a matter of debate whether the hormone-sensitive lipase (HSL)-mediated lipolysis in pancreatic β-cells can affect insulin secretion through the alteration of lipotoxicity. We generated mice lacking both leptin and HSL (Lep ob/ob /HSL -/- ) and explored the role of HSL in pancreatic β-cells in the setting of obesity. Lep ob/ob /HSL -/- developed elevated blood glucose levels and reduced plasma insulin levels compared with Lep ob/ob /HSL +/+ in a fed state, while the deficiency of HSL did not affect glucose homeostasis in Lep +/+ background. The deficiency of HSL exacerbated the accumulation of triglycerides in Lep ob/ob islets, leading to reduced glucose-stimulated insulin secretion. The deficiency of HSL also diminished the islet mass in Lep ob/ob mice due to decreased cell proliferation. In conclusion, HSL affects insulin secretary capacity especially in the setting of obesity.

  12. Inhibition of cholinergic potentiation of insulin secretion from pancreatic islets by chronic elevation of glucose and fatty acids: Protection by casein kinase 2 inhibitor

    Directory of Open Access Journals (Sweden)

    Nicolai M. Doliba

    2017-10-01

    Conclusions: These results show that chronic FA treatment decreases acetylcholine potentiation of insulin secretion and that this effect is strictly glucose dependent and might involve CK2 phosphorylation of β-cell M3 muscarinic receptors.

  13. A role for SPARC in the moderation of human insulin secretion.

    Directory of Open Access Journals (Sweden)

    Lorna W Harries

    Full Text Available AIMS/HYPOTHESIS: We have previously shown the implication of the multifunctional protein SPARC (Secreted protein acidic and rich in cysteine/osteonectin in insulin resistance but potential effects on beta-cell function have not been assessed. We therefore aimed to characterise the effect of SPARC on beta-cell function and features of diabetes. METHODS: We measured SPARC expression by qRT-PCR in human primary pancreatic islets, adipose tissue, liver and muscle. We then examined the relation of SPARC with glucose stimulated insulin secretion (GSIS in primary human islets and the effect of SPARC overexpression on GSIS in beta cell lines. RESULTS: SPARC was expressed at measurable levels in human islets, adipose tissue, liver and skeletal muscle, and demonstrated reduced expression in primary islets from subjects with diabetes compared with controls (p< = 0.05. SPARC levels were positively correlated with GSIS in islets from control donors (p< = 0.01. Overexpression of SPARC in cultured beta-cells resulted in a 2.4-fold increase in insulin secretion in high glucose conditions (p< = 0.01. CONCLUSIONS: Our data suggest that levels of SPARC are reduced in islets from donors with diabetes and that it has a role in insulin secretion, an effect which appears independent of SPARC's modulation of obesity-induced insulin resistance in adipose tissue.

  14. An ancestral role for the mitochondrial pyruvate carrier in glucose-stimulated insulin secretion

    OpenAIRE

    McCommis, Kyle S.; Hodges, Wesley T.; Bricker, Daniel K.; Wisidagama, Dona R.; Compan, Vincent; Remedi, Maria S.; Thummel, Carl S.; Finck, Brian N.

    2016-01-01

    Objective: Transport of pyruvate into the mitochondrial matrix by the Mitochondrial Pyruvate Carrier (MPC) is an important and rate-limiting step in its metabolism. In pancreatic β-cells, mitochondrial pyruvate metabolism is thought to be important for glucose sensing and glucose-stimulated insulin secretion. Methods: To evaluate the role that the MPC plays in maintaining systemic glucose homeostasis, we used genetically-engineered Drosophila and mice with loss of MPC activity in insulin-prod...

  15. Effect of Human Myotubes-Derived Media on Glucose-Stimulated Insulin Secretion

    Directory of Open Access Journals (Sweden)

    Maria L. Mizgier

    2017-01-01

    Full Text Available Fasting to postprandial transition requires a tight adjustment of insulin secretion to its demand, so tissue (e.g., skeletal muscle glucose supply is assured while hypo-/hyperglycemia are prevented. High muscle glucose disposal after meals is pivotal for adapting to increased glycemia and might drive insulin secretion through muscle-released factors (e.g., myokines. We hypothesized that insulin influences myokine secretion and then increases glucose-stimulated insulin secretion (GSIS. In conditioned media from human myotubes incubated with/without insulin (100 nmol/L for 24 h, myokines were qualitatively and quantitatively characterized using an antibody-based array and ELISA-based technology, respectively. C57BL6/J mice islets and Wistar rat beta cells were incubated for 24 h with control and conditioned media from noninsulin- and insulin-treated myotubes prior to GSIS determination. Conditioned media from insulin-treated versus nontreated myotubes had higher RANTES but lower IL6, IL8, and MCP1 concentration. Qualitative analyses revealed that conditioned media from noninsulin- and insulin-treated myotubes expressed 32 and 23 out of 80 myokines, respectively. Islets incubated with conditioned media from noninsulin-treated myotubes had higher GSIS versus control islets (p<0.05. Meanwhile, conditioned media from insulin-treated myotubes did not influence GSIS. In beta cells, GSIS was similar across conditions. In conclusion, factors being present in noninsulin-stimulated muscle cell-derived media appear to influence GSIS in mice islets.

  16. Integrative network analysis highlights biological processes underlying GLP-1 stimulated insulin secretion: A DIRECT study

    DEFF Research Database (Denmark)

    Gudmundsdottir, Valborg; Pedersen, Helle Krogh; Allebrandt, Karla Viviani

    2018-01-01

    Glucagon-like peptide 1 (GLP-1) stimulated insulin secretion has a considerable heritable component as estimated from twin studies, yet few genetic variants influencing this phenotype have been identified. We performed the first genome-wide association study (GWAS) of GLP-1 stimulated insulin...... secretion in non-diabetic individuals from the Netherlands Twin register (n = 126). This GWAS was enhanced using a tissue-specific protein-protein interaction network approach. We identified a beta-cell protein-protein interaction module that was significantly enriched for low gene scores based on the GWAS...... P-values and found support at the network level in an independent cohort from Tübingen, Germany (n = 100). Additionally, a polygenic risk score based on SNPs prioritized from the network was associated (P

  17. Linkage of the Nit1C gene cluster to bacterial cyanide assimilation as a nitrogen source.

    Science.gov (United States)

    Jones, Lauren B; Ghosh, Pallab; Lee, Jung-Hyun; Chou, Chia-Ni; Kunz, Daniel A

    2018-05-21

    A genetic linkage between a conserved gene cluster (Nit1C) and the ability of bacteria to utilize cyanide as the sole nitrogen source was demonstrated for nine different bacterial species. These included three strains whose cyanide nutritional ability has formerly been documented (Pseudomonas fluorescens Pf11764, Pseudomonas putida BCN3 and Klebsiella pneumoniae BCN33), and six not previously known to have this ability [Burkholderia (Paraburkholderia) xenovorans LB400, Paraburkholderia phymatum STM815, Paraburkholderia phytofirmans PsJN, Cupriavidus (Ralstonia) eutropha H16, Gluconoacetobacter diazotrophicus PA1 5 and Methylobacterium extorquens AM1]. For all bacteria, growth on or exposure to cyanide led to the induction of the canonical nitrilase (NitC) linked to the gene cluster, and in the case of Pf11764 in particular, transcript levels of cluster genes (nitBCDEFGH) were raised, and a nitC knock-out mutant failed to grow. Further studies demonstrated that the highly conserved nitB gene product was also significantly elevated. Collectively, these findings provide strong evidence for a genetic linkage between Nit1C and bacterial growth on cyanide, supporting use of the term cyanotrophy in describing what may represent a new nutritional paradigm in microbiology. A broader search of Nit1C genes in presently available genomes revealed its presence in 270 different bacteria, all contained within the domain Bacteria, including Gram-positive Firmicutes and Actinobacteria, and Gram-negative Proteobacteria and Cyanobacteria. Absence of the cluster in the Archaea is congruent with events that may have led to the inception of Nit1C occurring coincidentally with the first appearance of cyanogenic species on Earth, dating back 400-500 million years.

  18. Insulin secretion and action in North Indian women during pregnancy

    DEFF Research Database (Denmark)

    Arora, G P; Almgren, P; Thaman, R G

    2017-01-01

    . RESULTS: Gestational diabetes defined using both criteria was associated with decreased insulin secretion compared with pregnant women with normal glucose tolerance. Women with gestational diabetes defined by the adapted GDM2013, but not GDM1999 criteria, were more insulin resistant than pregnant women......AIM: The relative roles(s) of impaired insulin secretion vs. insulin resistance in the development of gestational diabetes mellitus depend upon multiple risk factors and diagnostic criteria. Here, we explored their relative contribution to gestational diabetes as defined by the WHO 1999 (GDM1999...... independently associated with increased insulin resistance. CONCLUSIONS: Gestational diabetes risk factors influence insulin secretion and action in North Indian women in a differential manner. Gestational diabetes classified using the adapted GDM2013 compared with GDM1999 criteria is associated with more...

  19. Possible modulatory effect of endogenous islet catecholamines on insulin secretion

    Directory of Open Access Journals (Sweden)

    Gagliardino Juan J

    2001-10-01

    Full Text Available Abstract Background The possible participation of endogenous islet catecholamines (CAs in the control of insulin secretion was tested. Methods Glucose-induced insulin secretion was measured in the presence of 3-Iodo-L-Tyrosine (MIT, a specific inhibitor of tyrosine-hydroxylase activity, in fresh and precultured islets isolated from normal rats. Incubated islets were also used to measure CAs release in the presence of low and high glucose, and the effect of α2-(yohimbine [Y] and idazoxan [I] and α1-adrenergic antagonists (prazosin [P] and terazosin [T] upon insulin secretion elicited by high glucose. Results Fresh islets incubated with 16.7 mM glucose released significantly more insulin in the presence of 1 μM MIT (6.66 ± 0.39 vs 5.01 ± 0.43 ng/islet/h, p Conclusion Our results suggest that islet-originated CAs directly modulate insulin release in a paracrine manner.

  20. Validation of methods for measurement of insulin secretion in humans in vivo

    DEFF Research Database (Denmark)

    Kjems, L L; Christiansen, E; Vølund, A

    2000-01-01

    To detect and understand the changes in beta-cell function in the pathogenesis of type 2 diabetes, an accurate and precise estimation of prehepatic insulin secretion rate (ISR) is essential. There are two common methods to assess ISR, the deconvolution method (by Eaton and Polonsky)-considered th......To detect and understand the changes in beta-cell function in the pathogenesis of type 2 diabetes, an accurate and precise estimation of prehepatic insulin secretion rate (ISR) is essential. There are two common methods to assess ISR, the deconvolution method (by Eaton and Polonsky...... of these mathematical techniques for quantification of insulin secretion have been tested in dogs, but not in humans. In the present studies, we examined the validity of both methods to recover the known infusion rates of insulin and C-peptide mimicking ISR during an oral glucose tolerance test. ISR from both......, and a close agreement was found for the results of an oral glucose tolerance test. We also studied whether C-peptide kinetics are influenced by somatostatin infusion. The decay curves after bolus injection of exogenous biosynthetic human C-peptide, the kinetic parameters, and the metabolic clearance rate were...

  1. A Unifying Organ Model of Pancreatic Insulin Secretion.

    Directory of Open Access Journals (Sweden)

    Andrea De Gaetano

    Full Text Available The secretion of insulin by the pancreas has been the object of much attention over the past several decades. Insulin is known to be secreted by pancreatic β-cells in response to hyperglycemia: its blood concentrations however exhibit both high-frequency (period approx. 10 minutes and low-frequency oscillations (period approx. 1.5 hours. Furthermore, characteristic insulin secretory response to challenge maneuvers have been described, such as frequency entrainment upon sinusoidal glycemic stimulation; substantial insulin peaks following minimal glucose administration; progressively strengthened insulin secretion response after repeated administration of the same amount of glucose; insulin and glucose characteristic curves after Intra-Venous administration of glucose boli in healthy and pre-diabetic subjects as well as in Type 2 Diabetes Mellitus. Previous modeling of β-cell physiology has been mainly directed to the intracellular chain of events giving rise to single-cell or cell-cluster hormone release oscillations, but the large size, long period and complex morphology of the diverse responses to whole-body glucose stimuli has not yet been coherently explained. Starting with the seminal work of Grodsky it was hypothesized that the population of pancreatic β-cells, possibly functionally aggregated in islets of Langerhans, could be viewed as a set of independent, similar, but not identical controllers (firing units with distributed functional parameters. The present work shows how a single model based on a population of independent islet controllers can reproduce very closely a diverse array of actually observed experimental results, with the same set of working parameters. The model's success in reproducing a diverse array of experiments implies that, in order to understand the macroscopic behaviour of the endocrine pancreas in regulating glycemia, there is no need to hypothesize intrapancreatic pacemakers, influences between different

  2. Effects of the beta-carbolines, harmane and pinoline, on insulin secretion from isolated human islets of Langerhans.

    Science.gov (United States)

    Cooper, E Jane; Hudson, Alan L; Parker, Christine A; Morgan, Noel G

    2003-12-15

    It is well known that certain imidazoline compounds can stimulate insulin secretion and this has been attributed to the activation of imidazoline I(3) binding sites in the pancreatic beta-cell. Recently, it has been proposed that beta-carbolines may be endogenous ligands having activity at imidazoline sites and we have, therefore, studied the effects of beta-carbolines on insulin secretion. The beta-carbolines harmane, norharmane and pinoline increased insulin secretion two- to threefold from isolated human islets of Langerhans. The effects of harmane and pinoline were dose-dependent (EC(50): 5 and 25 microM, respectively) and these agents also blocked the inhibitory effects of the potassium channel agonist, diazoxide, on glucose-induced insulin release. Stimulation of insulin secretion by harmane was glucose-dependent but, unlike the imidazoline I(3) receptor agonist efaroxan, it increased the rate of insulin release beyond that elicited by 20 mM glucose (20 mM glucose alone: 253+/-34% vs. basal; 20 mM glucose plus 100 microM harmane: 327+/-15%; P<0.01). Stimulation of insulin secretion by harmane was attenuated by the imidazoline I(3) receptor antagonist KU14R (2 (2-ethyl 2,3-dihydro-2-benzofuranyl)-2-imidazole) and was reduced when islets were treated with efaroxan for 18 h, prior to the addition of harmane. The results reveal that beta-carbolines can potentiate the rate of insulin secretion from human islets and suggest that these agents may be useful prototypes for the development of novel insulin secretagogues.

  3. Altered pancreatic growth and insulin secretion in WSB/EiJ mice.

    Directory of Open Access Journals (Sweden)

    Maggie M Ho

    Full Text Available These data suggest that insulin secretion in WSB mice is blunted specifically in vivo, either due to a reduced insulin requirement and/or due to factors that are absent or destroyed in vitro. These studies also highlight the role of post-natal growth in determining adult β-cell mass. Mice are important animal models for the study of metabolic physiology and the genetics of complex traits. Wild-derived inbred mouse strains, such as WSB/EiJ (WSB, are unrelated to the commonly studied mouse strains and are valuable tools to identify novel genes that modify disease risk. We have previously shown that in contrast to C57BL/6J (B6 mice, WSB mice fed a high fat diet do not develop hyperinsulinemia or insulin resistance, and had nearly undetectable insulin secretion in response to an intraperitoneal glucose challenge. As hyperinsulinemia may drive obesity and insulin resistance, we examined whether defects in β-cell mass or function could contribute to the low insulin levels in WSB mice. In young WSB mice, β-cell mass was similar to B6 mice. However, we found that adult WSB mice had reduced β-cell mass due to reduced pancreatic weights. Pancreatic sizes were similar between the strains when normalized to body weight, suggesting their pancreatic size is appropriate to their body size in adults, but overall post-natal pancreatic growth was reduced in WSB mice compared to B6 mice. Islet architecture was normal in WSB mice. WSB mice had markedly increased insulin secretion from isolated islets in vitro. These data suggest that insulin secretion in WSB mice is blunted specifically in vivo, either due to a reduced insulin requirement and/or due to factors that are absent or destroyed in vitro. These studies suggest that WSB mice may provide novel insight into mechanisms regulating insulin secretion and also highlight the role of post-natal growth in determining adult β-cell mass.

  4. Fetal adaptations in insulin secretion result from high catecholamines during placental insufficiency.

    Science.gov (United States)

    Limesand, Sean W; Rozance, Paul J

    2017-08-01

    Placental insufficiency and intrauterine growth restriction (IUGR) of the fetus affects approximately 8% of all pregnancies and is associated with short- and long-term disturbances in metabolism. In pregnant sheep, experimental models with a small, defective placenta that restricts delivery of nutrients and oxygen to the fetus result in IUGR. Low blood oxygen concentrations increase fetal plasma catecholamine concentrations, which lower fetal insulin concentrations. All of these observations in sheep models with placental insufficiency are consistent with cases of human IUGR. We propose that sustained high catecholamine concentrations observed in the IUGR fetus produce developmental adaptations in pancreatic β-cells that impair fetal insulin secretion. Experimental evidence supporting this hypothesis shows that chronic elevation in circulating catecholamines in IUGR fetuses persistently inhibits insulin concentrations and secretion. Elevated catecholamines also allow for maintenance of a normal fetal basal metabolic rate despite low fetal insulin and glucose concentrations while suppressing fetal growth. Importantly, a compensatory augmentation in insulin secretion occurs following inhibition or cessation of catecholamine signalling in IUGR fetuses. This finding has been replicated in normally grown sheep fetuses following a 7-day noradrenaline (norepinephrine) infusion. Together, these programmed effects will potentially create an imbalance between insulin secretion and insulin-stimulated glucose utilization in the neonate which probably explains the transient hyperinsulinism and hypoglycaemia in some IUGR infants. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

  5. Methylated trivalent arsenicals are potent inhibitors of glucose stimulated insulin secretion by murine pancreatic islets

    Energy Technology Data Exchange (ETDEWEB)

    Douillet, Christelle [Department of Nutrition, Gillings School of Global Public Health, 2302 MHRC, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7461 (United States); Currier, Jenna [Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7461 (United States); Saunders, Jesse [Department of Nutrition, Gillings School of Global Public Health, 2302 MHRC, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7461 (United States); Bodnar, Wanda M. [Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7431 (United States); Matoušek, Tomáš [Institute of Analytical Chemistry of the ASCR, v.v.i., Veveří 97, 602 00 Brno (Czech Republic); Stýblo, Miroslav, E-mail: styblo@med.unc.edu [Department of Nutrition, Gillings School of Global Public Health, 2302 MHRC, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7461 (United States)

    2013-02-15

    Epidemiologic evidence has linked chronic exposure to inorganic arsenic (iAs) with an increased prevalence of diabetes mellitus. Laboratory studies have identified several mechanisms by which iAs can impair glucose homeostasis. We have previously shown that micromolar concentrations of arsenite (iAs{sup III}) or its methylated trivalent metabolites, methylarsonite (MAs{sup III}) and dimethylarsinite (DMAs{sup III}), inhibit the insulin-activated signal transduction pathway, resulting in insulin resistance in adipocytes. Our present study examined effects of the trivalent arsenicals on insulin secretion by intact pancreatic islets isolated from C57BL/6 mice. We found that 48-hour exposures to low subtoxic concentrations of iAs{sup III}, MAs{sup III} or DMAs{sup III} inhibited glucose-stimulated insulin secretion (GSIS), but not basal insulin secretion. MAs{sup III} and DMAs{sup III} were more potent than iAs{sup III} as GSIS inhibitors with estimated IC{sub 50} ≤ 0.1 μM. The exposures had little or no effects on insulin content of the islets or on insulin expression, suggesting that trivalent arsenicals interfere with mechanisms regulating packaging of the insulin transport vesicles or with translocation of these vesicles to the plasma membrane. Notably, the inhibition of GSIS by iAs{sup III}, MAs{sup III} or DMAs{sup III} could be reversed by a 24-hour incubation of the islets in arsenic-free medium. These results suggest that the insulin producing pancreatic β-cells are among the targets for iAs exposure and that the inhibition of GSIS by low concentrations of the methylated metabolites of iAs may be the key mechanism of iAs-induced diabetes. - Highlights: ► Trivalent arsenicals inhibit glucose stimulated insulin secretion by pancreatic islets. ► MAs{sup III} and DMAs{sup III} are more potent inhibitors than arsenite with IC{sub 50} ∼ 0.1 μM. ► The arsenicals have little or no effects on insulin expression in pancreatic islets. ► The inhibition of

  6. Methylated trivalent arsenicals are potent inhibitors of glucose stimulated insulin secretion by murine pancreatic islets

    International Nuclear Information System (INIS)

    Douillet, Christelle; Currier, Jenna; Saunders, Jesse; Bodnar, Wanda M.; Matoušek, Tomáš; Stýblo, Miroslav

    2013-01-01

    Epidemiologic evidence has linked chronic exposure to inorganic arsenic (iAs) with an increased prevalence of diabetes mellitus. Laboratory studies have identified several mechanisms by which iAs can impair glucose homeostasis. We have previously shown that micromolar concentrations of arsenite (iAs III ) or its methylated trivalent metabolites, methylarsonite (MAs III ) and dimethylarsinite (DMAs III ), inhibit the insulin-activated signal transduction pathway, resulting in insulin resistance in adipocytes. Our present study examined effects of the trivalent arsenicals on insulin secretion by intact pancreatic islets isolated from C57BL/6 mice. We found that 48-hour exposures to low subtoxic concentrations of iAs III , MAs III or DMAs III inhibited glucose-stimulated insulin secretion (GSIS), but not basal insulin secretion. MAs III and DMAs III were more potent than iAs III as GSIS inhibitors with estimated IC 50 ≤ 0.1 μM. The exposures had little or no effects on insulin content of the islets or on insulin expression, suggesting that trivalent arsenicals interfere with mechanisms regulating packaging of the insulin transport vesicles or with translocation of these vesicles to the plasma membrane. Notably, the inhibition of GSIS by iAs III , MAs III or DMAs III could be reversed by a 24-hour incubation of the islets in arsenic-free medium. These results suggest that the insulin producing pancreatic β-cells are among the targets for iAs exposure and that the inhibition of GSIS by low concentrations of the methylated metabolites of iAs may be the key mechanism of iAs-induced diabetes. - Highlights: ► Trivalent arsenicals inhibit glucose stimulated insulin secretion by pancreatic islets. ► MAs III and DMAs III are more potent inhibitors than arsenite with IC 50 ∼ 0.1 μM. ► The arsenicals have little or no effects on insulin expression in pancreatic islets. ► The inhibition of insulin secretion by arsenite, MAs III or DMAs III is reversible. ► Thus

  7. Histone deacetylase 3 inhibition improves glycaemia and insulin secretion in obese diabetic rats

    DEFF Research Database (Denmark)

    Lundh, Morten; Galbo, Thomas; Poulsen, Steen Seier

    2015-01-01

    Failure of pancreatic β cells to compensate for insulin resistance is a prerequisite for the development of type 2 diabetes. Sustained elevated circulating levels of free fatty acids and glucose contribute to β-cell failure. Selective inhibition of Histone deacetylase (HDAC)-3 protects pancreatic β...... cells against inflammatory and metabolic insults in vitro. Here we tested the ability of a selective HDAC3 inhibitor, BRD3308, to reduce hyperglycemia and increase insulin secretion in an animal model of type 2 diabetes. At diabetes onset, an ambulatory hyperglycemic clamp was performed. HDAC3......3 as a key therapeutic target for β-cell protection in type 2 diabetes....

  8. Neuronal calcium sensor synaptotagmin-9 is not involved in the regulation of glucose homeostasis or insulin secretion.

    Directory of Open Access Journals (Sweden)

    Natalia Gustavsson

    Full Text Available BACKGROUND: Insulin secretion is a complex and highly regulated process. It is well established that cytoplasmic calcium is a key regulator of insulin secretion, but how elevated intracellular calcium triggers insulin granule exocytosis remains unclear, and we have only begun to define the identities of proteins that are responsible for sensing calcium changes and for transmitting the calcium signal to release machineries. Synaptotagmins are primarily expressed in brain and endocrine cells and exhibit diverse calcium binding properties. Synaptotagmin-1, -2 and -9 are calcium sensors for fast neurotransmitter release in respective brain regions, while synaptotagmin-7 is a positive regulator of calcium-dependent insulin release. Unlike the three neuronal calcium sensors, whose deletion abolished fast neurotransmitter release, synaptotagmin-7 deletion resulted in only partial loss of calcium-dependent insulin secretion, thus suggesting that other calcium-sensors must participate in the regulation of insulin secretion. Of the other synaptotagmin isoforms that are present in pancreatic islets, the neuronal calcium sensor synaptotagmin-9 is expressed at the highest level after synaptotagmin-7. METHODOLOGY/PRINCIPAL FINDINGS: In this study we tested whether synaptotagmin-9 participates in the regulation of glucose-stimulated insulin release by using pancreas-specific synaptotagmin-9 knockout (p-S9X mice. Deletion of synaptotagmin-9 in the pancreas resulted in no changes in glucose homeostasis or body weight. Glucose tolerance, and insulin secretion in vivo and from isolated islets were not affected in the p-S9X mice. Single-cell capacitance measurements showed no difference in insulin granule exocytosis between p-S9X and control mice. CONCLUSIONS: Thus, synaptotagmin-9, although a major calcium sensor in the brain, is not involved in the regulation of glucose-stimulated insulin release from pancreatic β-cells.

  9. Neuronal calcium sensor synaptotagmin-9 is not involved in the regulation of glucose homeostasis or insulin secretion.

    Science.gov (United States)

    Gustavsson, Natalia; Wang, Xiaorui; Wang, Yue; Seah, Tingting; Xu, Jun; Radda, George K; Südhof, Thomas C; Han, Weiping

    2010-11-09

    Insulin secretion is a complex and highly regulated process. It is well established that cytoplasmic calcium is a key regulator of insulin secretion, but how elevated intracellular calcium triggers insulin granule exocytosis remains unclear, and we have only begun to define the identities of proteins that are responsible for sensing calcium changes and for transmitting the calcium signal to release machineries. Synaptotagmins are primarily expressed in brain and endocrine cells and exhibit diverse calcium binding properties. Synaptotagmin-1, -2 and -9 are calcium sensors for fast neurotransmitter release in respective brain regions, while synaptotagmin-7 is a positive regulator of calcium-dependent insulin release. Unlike the three neuronal calcium sensors, whose deletion abolished fast neurotransmitter release, synaptotagmin-7 deletion resulted in only partial loss of calcium-dependent insulin secretion, thus suggesting that other calcium-sensors must participate in the regulation of insulin secretion. Of the other synaptotagmin isoforms that are present in pancreatic islets, the neuronal calcium sensor synaptotagmin-9 is expressed at the highest level after synaptotagmin-7. In this study we tested whether synaptotagmin-9 participates in the regulation of glucose-stimulated insulin release by using pancreas-specific synaptotagmin-9 knockout (p-S9X) mice. Deletion of synaptotagmin-9 in the pancreas resulted in no changes in glucose homeostasis or body weight. Glucose tolerance, and insulin secretion in vivo and from isolated islets were not affected in the p-S9X mice. Single-cell capacitance measurements showed no difference in insulin granule exocytosis between p-S9X and control mice. Thus, synaptotagmin-9, although a major calcium sensor in the brain, is not involved in the regulation of glucose-stimulated insulin release from pancreatic β-cells.

  10. Kcne2 deletion impairs insulin secretion and causes type 2 diabetes mellitus.

    Science.gov (United States)

    Lee, Soo Min; Baik, Jasmine; Nguyen, Dara; Nguyen, Victoria; Liu, Shiwei; Hu, Zhaoyang; Abbott, Geoffrey W

    2017-06-01

    Type 2 diabetes mellitus (T2DM) represents a rapidly increasing threat to global public health. T2DM arises largely from obesity, poor diet, and lack of exercise, but it also involves genetic predisposition. Here we report that the KCNE2 potassium channel transmembrane regulatory subunit is expressed in human and mouse pancreatic β cells. Kcne2 deletion in mice impaired glucose tolerance as early as 5 wk of age in pups fed a Western diet, ultimately causing diabetes. In adult mice fed normal chow, skeletal muscle expression of insulin receptor β and insulin receptor substrate 1 were down-regulated 2-fold by Kcne2 deletion, characteristic of T2DM. Kcne2 deletion also caused extensive pancreatic transcriptome changes consistent with facets of T2DM, including endoplasmic reticulum stress, inflammation, and hyperproliferation. Kcne2 deletion impaired β-cell insulin secretion in vitro up to 8-fold and diminished β-cell peak outward K + current at positive membrane potentials, but also left-shifted its voltage dependence and slowed inactivation. Interestingly, we also observed an aging-dependent reduction in β-cell outward currents in both Kcne2 +/+ and Kcne2 - / - mice. Our results demonstrate that KCNE2 is required for normal β-cell electrical activity and insulin secretion, and that Kcne2 deletion causes T2DM. KCNE2 may regulate multiple K + channels in β cells, including the T2DM-linked KCNQ1 potassium channel α subunit.-Lee, S. M., Baik, J., Nguyen, D., Nguyen, V., Liu, S., Hu, Z., Abbott, G. W. Kcne2 deletion impairs insulin secretion and causes type 2 diabetes mellitus. © FASEB.

  11. Expression and functional assessment of candidate type 2 diabetes susceptibility genes identify four new genes contributing to human insulin secretion

    Directory of Open Access Journals (Sweden)

    Fatou K. Ndiaye

    2017-06-01

    Full Text Available Objectives: Genome-wide association studies (GWAS have identified >100 loci independently contributing to type 2 diabetes (T2D risk. However, translational implications for precision medicine and for the development of novel treatments have been disappointing, due to poor knowledge of how these loci impact T2D pathophysiology. Here, we aimed to measure the expression of genes located nearby T2D associated signals and to assess their effect on insulin secretion from pancreatic beta cells. Methods: The expression of 104 candidate T2D susceptibility genes was measured in a human multi-tissue panel, through PCR-free expression assay. The effects of the knockdown of beta-cell enriched genes were next investigated on insulin secretion from the human EndoC-βH1 beta-cell line. Finally, we performed RNA-sequencing (RNA-seq so as to assess the pathways affected by the knockdown of the new genes impacting insulin secretion from EndoC-βH1, and we analyzed the expression of the new genes in mouse models with altered pancreatic beta-cell function. Results: We found that the candidate T2D susceptibility genes' expression is significantly enriched in pancreatic beta cells obtained by laser capture microdissection or sorted by flow cytometry and in EndoC-βH1 cells, but not in insulin sensitive tissues. Furthermore, the knockdown of seven T2D-susceptibility genes (CDKN2A, GCK, HNF4A, KCNK16, SLC30A8, TBC1D4, and TCF19 with already known expression and/or function in beta cells changed insulin secretion, supporting our functional approach. We showed first evidence for a role in insulin secretion of four candidate T2D-susceptibility genes (PRC1, SRR, ZFAND3, and ZFAND6 with no previous knowledge of presence and function in beta cells. RNA-seq in EndoC-βH1 cells with decreased expression of PRC1, SRR, ZFAND6, or ZFAND3 identified specific gene networks related to T2D pathophysiology. Finally, a positive correlation between the expression of Ins2 and the

  12. Does epigenetic dysregulation of pancreatic islets contribute to impaired insulin secretion and type 2 diabetes?

    Science.gov (United States)

    Dayeh, Tasnim; Ling, Charlotte

    2015-10-01

    β cell dysfunction is central to the development and progression of type 2 diabetes (T2D). T2D develops when β cells are not able to compensate for the increasing demand for insulin caused by insulin resistance. Epigenetic modifications play an important role in establishing and maintaining β cell identity and function in physiological conditions. On the other hand, epigenetic dysregulation can cause a loss of β cell identity, which is characterized by reduced expression of genes that are important for β cell function, ectopic expression of genes that are not supposed to be expressed in β cells, and loss of genetic imprinting. Consequently, this may lead to β cell dysfunction and impaired insulin secretion. Risk factors that can cause epigenetic dysregulation include parental obesity, an adverse intrauterine environment, hyperglycemia, lipotoxicity, aging, physical inactivity, and mitochondrial dysfunction. These risk factors can affect the epigenome at different time points throughout the lifetime of an individual and even before an individual is conceived. The plasticity of the epigenome enables it to change in response to environmental factors such as diet and exercise, and also makes the epigenome a good target for epigenetic drugs that may be used to enhance insulin secretion and potentially treat diabetes.

  13. Plasma HDL-cholesterol and triglycerides, but not LDL-cholesterol, are associated with insulin secretion in non-diabetic subjects.

    Science.gov (United States)

    Natali, Andrea; Baldi, Simona; Bonnet, Fabrice; Petrie, John; Trifirò, Silvia; Tricò, Domenico; Mari, Andrea

    2017-04-01

    Experimental data support the notion that lipoproteins might directly affect beta cell function, however clinical data are sparse and inconsistent. We aimed at verifying whether, independently of major confounders, serum lipids are associated with alterations in insulin secretion or clearance non-diabetic subjects. Cross sectional and observational prospective (3.5yrs), multicentre study in which 1016 non-diabetic volunteers aged 30-60yrs. and with a wide range of BMI (20.0-39.9kg/m 2 ) were recruited in a setting of University hospital ambulatory care (RISC study). baseline fasting lipids, fasting and OGTT-induced insulin secretion and clearance (measured by glucose and C-peptide modeling), peripheral insulin sensitivity (by the euglycemic clamp). Lipids and OGTT were repeated in 980 subjects after 3.5years. LDL-cholesterol did not show independent associations with fasting or stimulated insulin secretion or clearance. After accounting for potential confounders, HDL-cholesterol displayed negative and triglycerides positive independent associations with fasting and OGTT insulin secretion; neither with insulin clearance. Low HDL-cholesterol and high triglycerides were associated with an increase in glucose-dependent and a decrease in non-glucose-dependent insulin secretion. Over 3.5years both an HDL-cholesterol decline and a triglycerides rise were associated with an increase in fasting insulin secretion independent of changes in body weight or plasma glucose. LDL-cholesterol does not seem to influence any major determinant of insulin bioavailability while low HDL-cholesterol and high triglycerides might contribute to sustain the abnormalities in insulin secretion that characterize the pre-diabetic state. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Delta-like Ligand-4-Notch Signaling Inhibition Regulates Pancreatic Islet Function and Insulin Secretion

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    Fabienne Billiard

    2018-01-01

    Full Text Available Although Notch signaling has been proposed as a therapeutic target for type-2 diabetes, liver steatosis, and atherosclerosis, its direct effect on pancreatic islets remains unknown. Here, we demonstrated a function of Dll4-Notch signaling inhibition on the biology of insulin-producing cells. We confirmed enhanced expression of key Notch signaling genes in purified pancreatic islets from diabetic NOD mice and showed that treatment with anti-Dll4 antibody specifically abolished Notch signaling pathway activation. Furthermore, we showed that Notch inhibition could drive proliferation of β-islet cells and confer protection from the development of STZ-induced diabetes. Importantly, inhibition of the Dll4 pathway in WT mice increased insulin secretion by inducing the differentiation of pancreatic β-islet cell progenitors, as well as the proliferation of insulin-secreting cells. These findings reveal a direct effect of Dll4-blockade on pancreatic islets that, in conjunction with its immunomodulatory effects, could be used for unmet medical needs hallmarked by inefficient insulin action.

  15. Regulation of Nampt expression by transcriptional coactivator NCOA6 in pancreatic β-cells

    International Nuclear Information System (INIS)

    Yoon, Jin; Lee, Kyung Jin; Oh, Gyun-Sik; Kim, Geun Hyang; Kim, Seung-Whan

    2017-01-01

    Nuclear receptor coactivator 6 (NCOA6) is a transcriptional coactivator and crucial for insulin secretion and glucose metabolism in pancreatic β-cells. However, the regulatory mechanism of β-cell function by NCOA6 is largely unknown. In this study, we found that the transcript levels of nicotinamide phosphoribosyltransferase (Nampt) were decreased in islets of NCOA6 +/− mice compared with NCOA6 +/+ mice. Moreover, NCOA6 overexpression increased the levels of Nampt transcripts in the mouse pancreatic β-cell line NIT-1. Promoter analyses showed that transcriptional activity of the Nampt promoter was stimulated by cooperation of sterol regulatory element binding protein-1c (SREBP-1c) and NCOA6. Additional studies using mutant promoters demonstrated that SREBP-1c activates Nampt promoter through the sterol regulatory element (SRE), but not through the E-box. Using chromatin immunoprecipitation assay, NCOA6 was also shown to be directly recruited to the SRE region of the Nampt promoter. Furthermore, treatment with nicotinamide mononucleotide (NMN), a product of the Nampt reaction and a key NAD + intermediate, ameliorates glucose-stimulated insulin secretion from NCOA6 +/− islets. These results suggest that NCOA6 stimulates insulin secretion, at least partially, by modulating Nampt expression in pancreatic β-cells. - Highlights: • Nampt transcription in β-cells is activated by SREBP-1c through the SRE element. • NCOA6 enhances the transcriptional activity of SREBP-1c in the Nampt promoter. • Defective insulin secretion of NCOA6 +/− islets is recovered by NMN treatment. • NCOA6 is reportedly the first coactivator involved in Nampt expression.

  16. Circulating Glucagon 1-61 Regulates Blood Glucose by Increasing Insulin Secretion and Hepatic Glucose Production

    Directory of Open Access Journals (Sweden)

    Nicolai J. Wewer Albrechtsen

    2017-11-01

    Full Text Available Glucagon is secreted from pancreatic α cells, and hypersecretion (hyperglucagonemia contributes to diabetic hyperglycemia. Molecular heterogeneity in hyperglucagonemia is poorly investigated. By screening human plasma using high-resolution-proteomics, we identified several glucagon variants, among which proglucagon 1-61 (PG 1-61 appears to be the most abundant form. PG 1-61 is secreted in subjects with obesity, both before and after gastric bypass surgery, with protein and fat as the main drivers for secretion before surgery, but glucose after. Studies in hepatocytes and in β cells demonstrated that PG 1-61 dose-dependently increases levels of cAMP, through the glucagon receptor, and increases insulin secretion and protein levels of enzymes regulating glycogenolysis and gluconeogenesis. In rats, PG 1-61 increases blood glucose and plasma insulin and decreases plasma levels of amino acids in vivo. We conclude that glucagon variants, such as PG 1-61, may contribute to glucose regulation by stimulating hepatic glucose production and insulin secretion.

  17. BAG3 regulates formation of the SNARE complex and insulin secretion

    Science.gov (United States)

    Iorio, V; Festa, M; Rosati, A; Hahne, M; Tiberti, C; Capunzo, M; De Laurenzi, V; Turco, M C

    2015-01-01

    Insulin release in response to glucose stimulation requires exocytosis of insulin-containing granules. Glucose stimulation of beta cells leads to focal adhesion kinase (FAK) phosphorylation, which acts on the Rho family proteins (Rho, Rac and Cdc42) that direct F-actin remodeling. This process requires docking and fusion of secretory vesicles to the release sites at the plasma membrane and is a complex mechanism that is mediated by SNAREs. This transiently disrupts the F-actin barrier and allows the redistribution of the insulin-containing granules to more peripheral regions of the β cell, hence facilitating insulin secretion. In this manuscript, we show for the first time that BAG3 plays an important role in this process. We show that BAG3 downregulation results in increased insulin secretion in response to glucose stimulation and in disruption of the F-actin network. Moreover, we show that BAG3 binds to SNAP-25 and syntaxin-1, two components of the t-SNARE complex preventing the interaction between SNAP-25 and syntaxin-1. Upon glucose stimulation BAG3 is phosphorylated by FAK and dissociates from SNAP-25 allowing the formation of the SNARE complex, destabilization of the F-actin network and insulin release. PMID:25766323

  18. L-cysteine reversibly inhibits glucose-induced biphasic insulin secretion and ATP production by inactivating PKM2.

    Science.gov (United States)

    Nakatsu, Daiki; Horiuchi, Yuta; Kano, Fumi; Noguchi, Yoshiyuki; Sugawara, Taichi; Takamoto, Iseki; Kubota, Naoto; Kadowaki, Takashi; Murata, Masayuki

    2015-03-10

    Increase in the concentration of plasma L-cysteine is closely associated with defective insulin secretion from pancreatic β-cells, which results in type 2 diabetes (T2D). In this study, we investigated the effects of prolonged L-cysteine treatment on glucose-stimulated insulin secretion (GSIS) from mouse insulinoma 6 (MIN6) cells and from mouse pancreatic islets, and found that the treatment reversibly inhibited glucose-induced ATP production and resulting GSIS without affecting proinsulin and insulin synthesis. Comprehensive metabolic analyses using capillary electrophoresis time-of-flight mass spectrometry showed that prolonged L-cysteine treatment decreased the levels of pyruvate and its downstream metabolites. In addition, methyl pyruvate, a membrane-permeable form of pyruvate, rescued L-cysteine-induced inhibition of GSIS. Based on these results, we found that both in vitro and in MIN6 cells, L-cysteine specifically inhibited the activity of pyruvate kinase muscle isoform 2 (PKM2), an isoform of pyruvate kinases that catalyze the conversion of phosphoenolpyruvate to pyruvate. L-cysteine also induced PKM2 subunit dissociation (tetramers to dimers/monomers) in cells, which resulted in impaired glucose-induced ATP production for GSIS. DASA-10 (NCGC00181061, a substituted N,N'-diarylsulfonamide), a specific activator for PKM2, restored the tetramer formation and the activity of PKM2, glucose-induced ATP production, and biphasic insulin secretion in L-cysteine-treated cells. Collectively, our results demonstrate that impaired insulin secretion due to exposure to L-cysteine resulted from its direct binding and inactivation of PKM2 and suggest that PKM2 is a potential therapeutic target for T2D.

  19. Similar weight-adjusted insulin secretion and insulin sensitivity in short-duration late autoimmune diabetes of adulthood (LADA) and Type 2 diabetes

    DEFF Research Database (Denmark)

    Juhl, C B; Bradley, U; Holst, Jens Juul

    2014-01-01

    AIMS: To explore insulin sensitivity and insulin secretion in people with latent autoimmune diabetes in adulthood (LADA) compared with that in people with Type 2 diabetes. METHODS: A total of 12 people with LADA, defined as glutamic acid decarboxylase (GAD) antibody positivity and > 1 year...... of insulin independency (group A) were age-matched pairwise to people with Type 2 diabetes (group B) and to six people with Type 2 diabetes of similar age and BMI (group C). β-cell function (first-phase insulin secretion and assessment of insulin pulsatility), insulin sensitivity (hyperinsulinemic......-euglycemic clamp) and metabolic response during a mixed meal were studied. RESULTS: Both first-phase insulin secretion and insulin release during the meal were greater (P = 0.05 and P = 0.009, respectively) in Type 2 diabetes as compared with LADA; these differences were lost on adjustment for BMI (group C...

  20. Reevaluation of Fatty acid receptor 1 (FFAR1/GPR40) as drug target for the stimulation of insulin secretion in humans

    DEFF Research Database (Denmark)

    Wagner, Robert; Kaiser, Gabriele; Gerst, Felicia

    2013-01-01

    The role of free fatty acid receptor 1 (FFAR1/GPR40) in glucose homeostasis is still incompletely understood. Small receptor agonists stimulating insulin secretion are under investigation for the treatment of type 2 diabetes. Surprisingly, genome-wide association studies did not discover diabetes...... risk variants in FFAR1. We reevaluated the role of FFAR1 in insulin secretion using a specific agonist, FFAR1-knockout mice and human islets. Nondiabetic individuals were metabolically phenotyped and genotyped. In vitro experiments indicated that palmitate and a specific FFAR1-agonist, TUG-469......, stimulate glucose-induced insulin secretion through FFAR1. The pro-apoptotic effect of chronic exposure of beta-cells to palmitate was independent of FFAR1. TUG-469 was protective, while inhibition of FFAR1 promoted apoptosis. In accordance with the pro-apoptotic effect of palmitate, in vivo crosssectional...

  1. Neuronal calcium sensor synaptotagmin-9 is not involved in the regulation of glucose homeostasis or insulin secretion

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Wang, Xiaorui; Wang, Yue

    2010-01-01

    the identities of proteins that are responsible for sensing calcium changes and for transmitting the calcium signal to release machineries. Synaptotagmins are primarily expressed in brain and endocrine cells and exhibit diverse calcium binding properties. Synaptotagmin-1, -2 and -9 are calcium sensors for fast......BACKGROUND: Insulin secretion is a complex and highly regulated process. It is well established that cytoplasmic calcium is a key regulator of insulin secretion, but how elevated intracellular calcium triggers insulin granule exocytosis remains unclear, and we have only begun to define...... neurotransmitter release in respective brain regions, while synaptotagmin-7 is a positive regulator of calcium-dependent insulin release. Unlike the three neuronal calcium sensors, whose deletion abolished fast neurotransmitter release, synaptotagmin-7 deletion resulted in only partial loss of calcium...

  2. Sex-specific effects of naturally occurring variants in the dopamine receptor D2 locus on insulin secretion and Type 2 diabetes susceptibility

    DEFF Research Database (Denmark)

    Guigas, B; de Leeuw van Weenen, J E; van Leeuwen, N

    2014-01-01

    AIMS: Modulation of dopamine receptor D2 (DRD2) activity affects insulin secretion in both rodents and isolated pancreatic β-cells. We hypothesized that single nucleotide polymorphisms in the DRD2/ANKK1 locus may affect susceptibility to Type 2 diabetes in humans. METHODS: Four potentially....... In addition, 340 Dutch subjects underwent a 2-h hyperglycaemic clamp to investigate insulin secretion. Since sexual dimorphic associations related to DRD2 polymorphisms have been previously reported, we also performed a gender-stratified analysis. RESULTS: rs1800497 at the DRD2/ANKK1 locus was associated...

  3. Genomic analysis of Bacillus subtilis lytic bacteriophage ϕNIT1 capable of obstructing natto fermentation carrying genes for the capsule-lytic soluble enzymes poly-γ-glutamate hydrolase and levanase.

    Science.gov (United States)

    Ozaki, Tatsuro; Abe, Naoki; Kimura, Keitarou; Suzuki, Atsuto; Kaneko, Jun

    2017-01-01

    Bacillus subtilis strains including the fermented soybean (natto) starter produce capsular polymers consisting of poly-γ-glutamate and levan. Capsular polymers may protect the cells from phage infection. However, bacteriophage ϕNIT1 carries a γ-PGA hydrolase gene (pghP) that help it to counteract the host cell's protection strategy. ϕNIT had a linear double stranded DNA genome of 155,631-bp with a terminal redundancy of 5,103-bp, containing a gene encoding an active levan hydrolase. These capsule-lytic enzyme genes were located in the possible foreign gene cluster regions between central core and terminal redundant regions, and were expressed at the late phase of the phage lytic cycle. All tested natto origin Spounavirinae phages carried both genes for capsule degrading enzymes similar to ϕNIT1. A comparative genomic analysis revealed the diversity among ϕNIT1 and Bacillus phages carrying pghP-like and levan-hydrolase genes, and provides novel understanding on the acquisition mechanism of these enzymatic genes.

  4. Hypothesis: Musculin is a hormone secreted by skeletal muscle, the body's largest endocrine organ. Evidence for actions on the endocrine pancreas to restrain the beta-cell mass and to inhibit insulin secretion and on the hypothalamus to co-ordinate the neuroendocrine and appetite responses to exercise.

    Science.gov (United States)

    Engler, Dennis

    2007-01-01

    Recent studies indicate that skeletal muscle may act as an endocrine organ by secreting interleukin-6 (IL-6) into the systemic circulation. From an analysis of the actions of IL-6 and of additional literature, we postulate that skeletal muscle also secretes an unidentified hormone, which we have named Musculin (Latin: musculus = muscle), which acts on the pancreatic beta-cell to restrain the size of the (beta-cell mass and to tonically inhibit insulin secretion and biosynthesis. It is suggested that the amount of Musculin secreted is determined by, and is positively correlated with, the prevailing insulin sensitivity of skeletal muscle, thereby accounting for the hyperinsulinemia that occurs in insulin resistant disorders such as type 2 diabetes mellitus, obesity, and the polycystic ovary syndrome. In addition, it is postulated that Musculin acts on the hypothalamus (arcuate nucleus, dorsomedial hypothalamic nucleus) to co-ordinate the neuroendocrine and appetite responses to exercise. However, the possibilities that Musculin may act on additional central nervous system sites and that an additional hormone(s) may be responsible for these actions are not excluded. It is suggested that a search be made for Musculin, since analogues of such a substance may be of therapeutic benefit in the treatment of the current global diabetes and obesity epidemic.

  5. Circulating Glucagon 1-61 Regulates Blood Glucose by Increasing Insulin Secretion and Hepatic Glucose Production

    DEFF Research Database (Denmark)

    Wewer Albrechtsen, Nicolai J.; Kuhre, Rune E.; Hornburg, Daniel

    2017-01-01

    that PG 1-61 dose-dependently increases levels of cAMP, through the glucagon receptor, and increases insulin secretion and protein levels of enzymes regulating glycogenolysis and gluconeogenesis. In rats, PG 1-61 increases blood glucose and plasma insulin and decreases plasma levels of amino acids in......Glucagon is secreted from pancreatic α cells, and hypersecretion (hyperglucagonemia) contributes to diabetic hyperglycemia. Molecular heterogeneity in hyperglucagonemia is poorly investigated. By screening human plasma using high-resolution-proteomics, we identified several glucagon variants, among...... which proglucagon 1-61 (PG 1-61) appears to be the most abundant form. PG 1-61 is secreted in subjects with obesity, both before and after gastric bypass surgery, with protein and fat as the main drivers for secretion before surgery, but glucose after. Studies in hepatocytes and in β cells demonstrated...

  6. Calcineurin inhibitors acutely improve insulin sensitivity without affecting insulin secretion in healthy human volunteers

    DEFF Research Database (Denmark)

    Øzbay, Aygen; Møller, Niels; Juhl, Claus

    2012-01-01

    and tacrolimus has been attributed to both beta cell dysfunction and impaired insulin sensitivity. WHAT THIS STUDY ADDS: This is the first trial to investigate beta cell function and insulin sensitivity using gold standard methodology in healthy human volunteers treated with clinically relevant doses...... of ciclosporin and tacrolimus. We document that both drugs acutely increase insulin sensitivity, while first phase and pulsatile insulin secretion remain unaffected. This study demonstrates that ciclosporin and tacrolimus have similar acute effects on glucose metabolism in healthy humans. AIM The introduction...... of calcineurin inhibitors (CNIs) ciclosporin (CsA) and tacrolimus (Tac) has improved the outcome of organ transplants, but complications such as new onset diabetes mellitus after transplantation (NODAT) cause impairment of survival rates. The relative contribution of each CNI to the pathogenesis and development...

  7. Incretins, insulin secretion and Type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Vilsbøll, Tina; Holst, Jens Møller

    2004-01-01

    the genes encoding their receptors have been deleted. In patients with Type 2 diabetes, the incretin effect is either greatly impaired or absent, and it is assumed that this could contribute to the inability of these patients to adjust their insulin secretion to their needs. In studies of the mechanism...... of the impaired incretin effect in Type 2 diabetic patients, it has been found that the secretion of GIP is generally normal, whereas the secretion of GLP-1 is reduced, presumably as a consequence of the diabetic state. It might be of even greater importance that the effect of GLP-1 is preserved whereas...... the effect of GIP is severely impaired. The impaired GIP effect seems to have a genetic background, but could be aggravated by the diabetic state. The preserved effect of GLP-1 has inspired attempts to treat Type 2 diabetes with GLP-1 or analogues thereof, and intravenous GLP-1 administration has been shown...

  8. Incretins, insulin secretion and Type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Vilsbøll, T; Holst, Jens Juul

    2004-01-01

    the effect of GIP is severely impaired. The impaired GIP effect seems to have a genetic background, but could be aggravated by the diabetic state. The preserved effect of GLP-1 has inspired attempts to treat Type 2 diabetes with GLP-1 or analogues thereof, and intravenous GLP-1 administration has been shown...... the genes encoding their receptors have been deleted. In patients with Type 2 diabetes, the incretin effect is either greatly impaired or absent, and it is assumed that this could contribute to the inability of these patients to adjust their insulin secretion to their needs. In studies of the mechanism...... of the impaired incretin effect in Type 2 diabetic patients, it has been found that the secretion of GIP is generally normal, whereas the secretion of GLP-1 is reduced, presumably as a consequence of the diabetic state. It might be of even greater importance that the effect of GLP-1 is preserved whereas...

  9. Importance of radioimmunoassay of insulin secretion disorder as atherogenic factor

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Yu A; Bespalova, V A; Vakhrusheva, L L; Kirbasova, N P; Severtseva, V V

    1984-11-01

    Using a radioimmunoassay a C-peptide levei was revealed in children, pregnant and lying-in women as well as in patients with insulin-dependent diabetes mellitus. After breakfast and insulin administration wich curative purposes the IRI concentration in children increased whereas the C-peptide level changed insignificantly. Changes of the insulin secretion were more noticeable in severe diabetes mejlitus with vascular complications and in disease decompensation. The atherogenic nature of the lipid metaboiism (an increase in the cholesterol, triglyceride and ..beta..-lipoprotein levels), changes in the liver and tendency to vascular involvement are results of insulin effect inadequacy. Such metabolic derangements in pregnant women create unfavorable conditions for the development of fetus and may lead to early atherogenic processes.

  10. Using Glucose Tolerance Tests to Model Insulin Secretion and Clearance

    Directory of Open Access Journals (Sweden)

    Anthony Shannon

    2005-04-01

    Full Text Available The purpose of the studies described in this paper is to develop theoretically and to validate experimentally mathematical compartment models which can be used to predict plasma insulin levels in patients with diabetes mellitus (DM. In the case of Type 2 Diabetes Mellitus (T2DM, the C-peptide levels in the plasma were measured as part of routine glucose tolerance tests in order to estimate the prehepatic insulin secretion rates. In the case of Type 1 Diabetes Mellitus (T1DM, a radioactive labelled insulin was used to measure the absorption rate of insulin after a subcutaneous injection of insulin. Both models gave close fits between theoretical estimates and experimental data, and, unlike other models, it is not necessary to seed these models with initial estimates.

  11. Sex-specific effects of naturally occurring variants in the dopamine receptor D2 locus on insulin secretion and Type 2 diabetes susceptibility

    NARCIS (Netherlands)

    Guigas, B.; Leeuw van Weenen, J.E. de; van Leeuwen, N.; Simonis-Bik, A.M.; Haeften, T.W. van; Nijpels, G.; Houwing-Duistermaat, J.J.; Beekman, M.; Deelen, J.; Havekes, L.M.; Penninx, B.W.J.H.; Vogelzangs, N.; Riet, E. van 't; Dehghan, A.; Hofman, A.; Witteman, J.C.; Uitterlinden, A.G.; Grarup, N.; Jørgensen, T.; Witte, D.R.; Lauritzen, T.; Hansen, T.; Pedersen, O.; Hottenga, J.; Romijn, J.A.; Diamant, M.; Kramer, M.H.H.; Heine, R.J.; Willemsen, G.; Dekker, J.M.; Eekhoff, E.M.; Pijl, H.; Geus, E.J. de; Slagboom, P.E.; Hart, L.M. 't

    2014-01-01

    Aims: Modulation of dopamine receptor D2 (DRD2) activity affects insulin secretion in both rodents and isolated pancreatic β-cells. We hypothesized that single nucleotide polymorphisms in the DRD2/ANKK1 locus may affect susceptibility to Type 2 diabetes in humans. Methods: Four potentially

  12. Decrement of postprandial insulin secretion determines the progressive nature of type-2 diabetes.

    Science.gov (United States)

    Shim, Wan Sub; Kim, Soo Kyung; Kim, Hae Jin; Kang, Eun Seok; Ahn, Chul Woo; Lim, Sung Kil; Lee, Hyun Chul; Cha, Bong Soo

    2006-10-01

    Type-2 diabetes is a progressive disease. However, little is known about whether decreased fasting or postprandial pancreatic beta-cell responsiveness is more prominent with increased duration of diabetes. The aim of this study was to evaluate the relationship between insulin secretion both during fasting and 2 h postprandial, and the duration of diabetes in type-2 diabetic patients. Cross-sectional clinical investigation. We conducted a meal tolerance test in 1466 type-2 diabetic patients and calculated fasting (M0) and postprandial (M1) beta-cell responsiveness. The fasting C-peptide, postprandial C-peptide, M0, and M1 values were lower, but HbA1c values were higher, in patients with diabetes duration > 10 years than those in other groups. There was no difference in the HbA1c levels according to the tertiles of their fasting C-peptide level. However, in a group of patients with highest postprandial C-peptide tertile, the HbA1c values were significantly lower than those in other groups. After adjustment of age, sex, and body mass index (BMI), the duration of diabetes was found to be negatively correlated with fasting C-peptide (gamma = -0.102), postprandial C-peptide (gamma = -0.356), M0 (gamma = -0.263), and M1 (gamma = -0.315; P multiple regression analysis, M0, M1, and homeostasis model assessment for insulin resistance (HOMA-IR) emerged as predictors of HbAlc after adjustment for age, sex, and BMI (R2 = 0.272, 0.080, and 0.056 respectively). With increasing duration of diabetes, the decrease of postprandial insulin secretion is becoming more prominent, and postprandial beta-cell responsiveness may be a more important determinant for glycemic control than fasting beta-cell responsiveness.

  13. Control of the intracellular redox state by glucose participates in the insulin secretion mechanism.

    Directory of Open Access Journals (Sweden)

    Eduardo Rebelato

    Full Text Available BACKGROUND: Production of reactive oxygen species (ROS due to chronic exposure to glucose has been associated with impaired beta cell function and diabetes. However, physiologically, beta cells are well equipped to deal with episodic glucose loads, to which they respond with a fine tuned glucose-stimulated insulin secretion (GSIS. In the present study, a systematic investigation in rat pancreatic islets about the changes in the redox environment induced by acute exposure to glucose was carried out. METHODOLOGY/PRINCIPAL FINDINGS: Short term incubations were performed in isolated rat pancreatic islets. Glucose dose- and time-dependently reduced the intracellular ROS content in pancreatic islets as assayed by fluorescence in a confocal microscope. This decrease was due to activation of pentose-phosphate pathway (PPP. Inhibition of PPP blunted the redox control as well as GSIS in a dose-dependent manner. The addition of low doses of ROS scavengers at high glucose concentration acutely improved beta cell function. The ROS scavenger N-acetyl-L-cysteine increased the intracellular calcium response to glucose that was associated with a small decrease in ROS content. Additionally, the presence of the hydrogen peroxide-specific scavenger catalase, in its membrane-permeable form, nearly doubled glucose metabolism. Interestingly, though an increase in GSIS was also observed, this did not match the effect on glucose metabolism. CONCLUSIONS: The control of ROS content via PPP activation by glucose importantly contributes to the mechanisms that couple the glucose stimulus to insulin secretion. Moreover, we identified intracellular hydrogen peroxide as an inhibitor of glucose metabolism intrinsic to rat pancreatic islets. These findings suggest that the intracellular adjustment of the redox environment by glucose plays an important role in the mechanism of GSIS.

  14. Association of type 2 diabetes candidate polymorphisms in KCNQ1 with incretin and insulin secretion

    DEFF Research Database (Denmark)

    Müssig, Karsten; Staiger, Harald; Machicao, Fausto

    2009-01-01

    OBJECTIVE: KCNQ1 gene polymorphisms are associated with type 2 diabetes. This linkage appears to be mediated by altered beta-cell function. In an attempt to study underlying mechanisms, we examined the effect of four KCNQ1 single nucleotide polymorphisms (SNPs) on insulin secretion upon different...... stimuli. RESEARCH DESIGN AND METHODS: We genotyped 1,578 nondiabetic subjects at increased risk of type 2 diabetes for rs151290, rs2237892, rs2237895, and rs2237897. All participants underwent an oral glucose tolerance test (OGTT); glucagon-like peptide (GLP)-1 and gastric inhibitory peptide secretion...... was measured in 170 participants. In 519 participants, a hyperinsulinemic-euglycemic clamp was performed, in 314 participants an intravenous glucose tolerance test (IVGTT), and in 102 subjects a hyperglycemic clamp combined with GLP-1 and arginine stimuli. RESULTS: rs151290 was nominally associated with 30-min...

  15. Decreased insulin secretion in pregnant rats fed a low protein diet.

    Science.gov (United States)

    Gao, Haijun; Ho, Eric; Balakrishnan, Meena; Yechoor, Vijay; Yallampalli, Chandra

    2017-10-01

    Low protein (LP) diet during pregnancy leads to reduced plasma insulin levels in rodents, but the underlying mechanisms remain unclear. Glucose is the primary insulin secretagogue, and enhanced glucose-stimulated insulin secretion (GSIS) in beta cells contributes to compensation for insulin resistance and maintenance of glucose homeostasis during pregnancy. In this study, we hypothesized that plasma insulin levels in pregnant rats fed LP diet are reduced due to disrupted GSIS of pancreatic islets. We first confirmed reduced plasma insulin levels, then investigated in vivo insulin secretion by glucose tolerance test and ex vivo GSIS of pancreatic islets in the presence of glucose at different doses, and KCl, glibenclamide, and L-arginine. Main findings include (1) plasma insulin levels were unaltered on day 10, but significantly reduced on days 14-22 of pregnancy in rats fed LP diet compared to those of control (CT) rats; (2) insulin sensitivity was unchanged, but glucose intolerance was more severe in pregnant rats fed LP diet; (3) GSIS in pancreatic islets was lower in LP rats compared to CT rats in the presence of glucose, KCl, and glibenclamide, and the response to L-arginine was abolished in LP rats; and (4) the total insulin content in pancreatic islets and expression of Ins2 were reduced in LP rats, but expression of Gcg was unaltered. These studies demonstrate that decreased GSIS in beta cells of LP rats contributes to reduced plasma insulin levels, which may lead to placental and fetal growth restriction and programs hypertension and other metabolic diseases in offspring. © The Authors 2017. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. Cardiovascular side-effects and insulin secretion after intravenous administration of radiolabeled Exendin-4 in pigs

    International Nuclear Information System (INIS)

    Rydén, Anneli; Nyman, Görel; Nalin, Lovisa; Andreasson, Susanne; Korsgren, Olle; Eriksson, Olof; Jensen-Waern, Marianne

    2016-01-01

    Introduction: Radiolabeled Exendin-4, a synthetic glucagon-like peptide-1 (GLP-1) analog, is used as a tracer for diagnostic purposes of β-cells and in experimental animal research. Exendin-4 can be radiolabeled with 68 Ga, 111 In or 99m Tc and used for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging to diagnose insulinomas, visualization of pancreatic β-cell mass and transplanted Islets of Langerhans. In humans, Exendin-4 is widely used as a therapeutic agent for treatment of type 2 diabetes (T2D). The compound, which is administered subcutaneously (SC) may cause nausea, vomiting and a minor increase in the heart rate (HR). However, possible side-effects on cardiovascular functions after intravenous (IV) administration have not been reported. This study describes the Exendin-4 dose at which cardiovascular side-effects occur in pigs and cynomolgus monkeys. The IV effect of the tracer on insulin secretion is also investigated in pigs. Methods: Seven clinically healthy littermate pigs (40 days old) were used; three of them were made diabetic by streptozotocin (STZ). All pigs underwent PET imaging under general anesthesia to examine the glucagon-like peptide-1 receptor (GLP-1R) in β-cells with radiolabeled Exendin-4. A baseline tracer dose IV [ 68 Ga]Exendin-4 (0.025 ± 0.010 μg/kg) followed by a competition dose IV [ 68 Ga]Exendin-4 (3.98 ± 1.33 μg/kg) 60 min later were administered. Blood samples were taken and analyzed for insulin secretion by using ELISA. Cardiovascular and respiratory variables were monitored throughout the experiment. Results: Immediately after administration of the high dose [ 68 Ga]Exendin-4 the HR rose from 122 ± 14 to 227 ± 40 bpm (p < 0.01) and from 100 ± 5 to 181 ± 13 bpm (p < 0.01) in healthy non-diabetic and diabetes-induced pigs, respectively. The tachycardia was observed for > 2 h and one healthy non-diabetic pig suffered cardiac arrest 3 h after the IV [ 68 Ga]Exendin-4

  17. Combined contributions of over-secreted glucagon-like peptide 1 and suppressed insulin secretion to hyperglycemia induced by gatifloxacin in rats

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yunli, E-mail: chrisyu1255@yahoo.com.cn [Department of Pharmaceutics, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Wang, Xinting, E-mail: wxinting1986@yahoo.com.cn [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Liu, Can, E-mail: ltsan@163.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Yao, Dan, E-mail: erinyao@126.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Shanghai Institute of Materia Medica, Shanghai 201203 (China); Hu, Mengyue, E-mail: juliahmy@126.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Li, Jia, E-mail: ljbzd@163.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Hu, Nan, E-mail: hn_324@163.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Liu, Li, E-mail: liulee@cpu.edu.cn [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Liu, Xiaodong, E-mail: xdliu@cpu.edu.cn [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China)

    2013-02-01

    Accumulating evidences have showed that gatifloxacin causes dysglycemia in both diabetic and non-diabetic patients. Our preliminary study demonstrated that gatifloxacin stimulated glucagon-like peptide 1 (GLP-1) secretion from intestinal cells. The aim of the study was to investigate the association between gatifloxacin-stimulated GLP-1 release and dysglycemia in both normal and streptozotocin-induced diabetic rats and explore the possible mechanisms. Oral administration of gatifloxacin (100 mg/kg/day and 200 mg/kg/day) for 3 and 12 days led to marked elevation of GLP-1 levels, accompanied by significant decrease in insulin levels and increase in plasma glucose. Similar results were found in normal rats treated with 3-day gatifloxacin. Gatifloxacin-stimulated GLP-1 release was further confirmed in NCI-H716 cells, which was abolished by diazoxide, a K{sub ATP} channel opener. QT-PCR analysis showed that gatifloxacin also upregulated expression of proglucagon and prohormone convertase 3 mRNA. To clarify the contradiction on elevated GLP-1 without insulinotropic effect, effects of GLP-1 and gatifloxacin on insulin release were investigated using INS-1 cells. We found that short exposure (2 h) to GLP-1 stimulated insulin secretion and biosynthesis, whereas long exposure (24 h and 48 h) to high level of GLP-1 inhibited insulin secretion and biosynthesis. Moreover, we also confirmed gatifloxacin acutely stimulated insulin secretion while chronically inhibited insulin biosynthesis. All the results gave an inference that gatifloxacin stimulated over-secretion of GLP-1, in turn, high levels of GLP-1 and gatifloxacin synergistically impaired insulin release, worsening hyperglycemia. -- Highlights: ► Gatifloxacin induced hyperglycemia both in diabetic rats and normal rats. ► Gatifloxacin enhanced GLP-1 secretion but inhibited insulin secretion in rats. ► Long-term exposure to high GLP-1 inhibited insulin secretion and biosynthesis. ► GLP-1 over-secretion may be

  18. Combined contributions of over-secreted glucagon-like peptide 1 and suppressed insulin secretion to hyperglycemia induced by gatifloxacin in rats

    International Nuclear Information System (INIS)

    Yu, Yunli; Wang, Xinting; Liu, Can; Yao, Dan; Hu, Mengyue; Li, Jia; Hu, Nan; Liu, Li; Liu, Xiaodong

    2013-01-01

    Accumulating evidences have showed that gatifloxacin causes dysglycemia in both diabetic and non-diabetic patients. Our preliminary study demonstrated that gatifloxacin stimulated glucagon-like peptide 1 (GLP-1) secretion from intestinal cells. The aim of the study was to investigate the association between gatifloxacin-stimulated GLP-1 release and dysglycemia in both normal and streptozotocin-induced diabetic rats and explore the possible mechanisms. Oral administration of gatifloxacin (100 mg/kg/day and 200 mg/kg/day) for 3 and 12 days led to marked elevation of GLP-1 levels, accompanied by significant decrease in insulin levels and increase in plasma glucose. Similar results were found in normal rats treated with 3-day gatifloxacin. Gatifloxacin-stimulated GLP-1 release was further confirmed in NCI-H716 cells, which was abolished by diazoxide, a K ATP channel opener. QT-PCR analysis showed that gatifloxacin also upregulated expression of proglucagon and prohormone convertase 3 mRNA. To clarify the contradiction on elevated GLP-1 without insulinotropic effect, effects of GLP-1 and gatifloxacin on insulin release were investigated using INS-1 cells. We found that short exposure (2 h) to GLP-1 stimulated insulin secretion and biosynthesis, whereas long exposure (24 h and 48 h) to high level of GLP-1 inhibited insulin secretion and biosynthesis. Moreover, we also confirmed gatifloxacin acutely stimulated insulin secretion while chronically inhibited insulin biosynthesis. All the results gave an inference that gatifloxacin stimulated over-secretion of GLP-1, in turn, high levels of GLP-1 and gatifloxacin synergistically impaired insulin release, worsening hyperglycemia. -- Highlights: ► Gatifloxacin induced hyperglycemia both in diabetic rats and normal rats. ► Gatifloxacin enhanced GLP-1 secretion but inhibited insulin secretion in rats. ► Long-term exposure to high GLP-1 inhibited insulin secretion and biosynthesis. ► GLP-1 over-secretion may be involved in

  19. The Role of Taste in Cephalic Phase of Insulin Secretion

    Directory of Open Access Journals (Sweden)

    M. Dušková

    2013-01-01

    Full Text Available The effect of a short gustatory signal of a sweet solution was tested on 15 young male volunteers. The experiment consisted of mouth rinsing with either a sucrose or aspartate solution or pure water as a placebo. Blood was then taken in short intervals of 0, 5, 10, 15 and 20 min. Blood glucose, C-peptide, insulin and cortisol were determined. While C-peptide and glucose were unaffected, a short-term increase in insulin was observed after the sucrose, but not after the aspartate or placebo. The increase in insulin was significant, though it amounted to only 0.5 mIU/l and lasted approx. 15 min reaching then the starting value. The decline of cortisol level within 20 min of the experiment was approx. 40 nmol/l, although it was also observed after aspartate or placebo mouth rinsing and was probably caused by stress factors or anticipation. In conclusion, the contribution of taste to the cephalic phase of insulin secretion is small yet significant, and mouth rinsing with 5% sucrose causes an insulin increase of just under 1 IU/l, which returns to starting level within 15 min.

  20. SIRT4 Is a Lysine Deacylase that Controls Leucine Metabolism and Insulin Secretion

    DEFF Research Database (Denmark)

    Anderson, Kristin A; Huynh, Frank K; Fisher-Wellman, Kelsey

    2017-01-01

    in leucine oxidation, and we show a primary role for SIRT4 in controlling this pathway in mice. Furthermore, we find that dysregulated leucine metabolism in SIRT4KO mice leads to elevated basal and stimulated insulin secretion, which progressively develops into glucose intolerance and insulin resistance....... These findings identify a robust enzymatic activity for SIRT4, uncover a mechanism controlling branched-chain amino acid flux, and position SIRT4 as a crucial player maintaining insulin secretion and glucose homeostasis during aging....

  1. Restitution of defective glucose-stimulated insulin secretion in diabetic GK rat by acetylcholine uncovers paradoxical stimulatory effect of beta-cell muscarinic receptor activation on cAMP production.

    Science.gov (United States)

    Dolz, Manuel; Bailbé, Danielle; Giroix, Marie-Hélène; Calderari, Sophie; Gangnerau, Marie-Noelle; Serradas, Patricia; Rickenbach, Katharina; Irminger, Jean-Claude; Portha, Bernard

    2005-11-01

    Because acetylcholine (ACh) is a recognized potentiator of glucose-stimulated insulin release in the normal beta-cell, we have studied ACh's effect on islets of the Goto-Kakizaki (GK) rat, a spontaneous model of type 2 diabetes. We first verified that ACh was able to restore the insulin secretory glucose competence of the GK beta-cell. Then, we demonstrated that in GK islets 1) ACh elicited a first-phase insulin release at low glucose, whereas it had no effect in Wistar; 2) total phospholipase C activity, ACh-induced inositol phosphate production, and intracellular free calcium concentration ([Ca2+]i) elevation were normal; 3) ACh triggered insulin release, even in the presence of thapsigargin, which induced a reduction of the ACh-induced [Ca2+]i response (suggesting that ACh produces amplification signals that augment the efficacy of elevated [Ca2+]i on GK exocytosis); 4) inhibition of protein kinase C did not affect [Ca2+]i nor the insulin release responses to ACh; and 5) inhibition of cAMP-dependent protein kinases (PKAs), adenylyl cyclases, or cAMP generation, while not affecting the [Ca2+]i response, significantly lowered the insulinotropic response to ACh (at low and high glucose). In conclusion, ACh acts mainly through activation of the cAMP/PKA pathway to potently enhance Ca2+-stimulated insulin release in the GK beta-cell and, in doing so, normalizes its defective glucose responsiveness.

  2. Fuel-Stimulated Insulin Secretion Depends upon Mitochondria Activation and the Integration of Mitochondrial and Cytosolic Substrate Cycles

    Directory of Open Access Journals (Sweden)

    Gary W. Cline

    2011-10-01

    Full Text Available The pancreatic islet β-cell is uniquely specialized to couple its metabolism and rates of insulin secretion with the levels of circulating nutrient fuels, with the mitochondrial playing a central regulatory role in this process. In the β-cell, mitochondrial activation generates an integrated signal reflecting rates of oxidativephosphorylation, Kreb's cycle flux, and anaplerosis that ultimately determines the rate of insulin exocytosis. Mitochondrial activation can be regulated by proton leak and mediated by UCP2, and by alkalinization to utilize the pH gradient to drive substrate and ion transport. Converging lines of evidence support the hypothesis that substrate cycles driven by rates of Kreb's cycle flux and by anaplerosis play an integral role in coupling responsive changes in mitochondrial metabolism with insulin secretion. The components and mechanisms that account for the integrated signal of ATP production, substrate cycling, the regulation of cellular redox state, and the production of other secondary signaling intermediates are operative in both rodent and human islet β-cells.

  3. Stress-induced dissociations between intracellular calcium signaling and insulin secretion in pancreatic islets.

    Science.gov (United States)

    Qureshi, Farhan M; Dejene, Eden A; Corbin, Kathryn L; Nunemaker, Craig S

    2015-05-01

    In healthy pancreatic islets, glucose-stimulated changes in intracellular calcium ([Ca(2+)]i) provide a reasonable reflection of the patterns and relative amounts of insulin secretion. We report that [Ca(2+)]i in islets under stress, however, dissociates with insulin release in different ways for different stressors. Islets were exposed for 48h to a variety of stressors: cytokines (low-grade inflammation), 28mM glucose (28G, glucotoxicity), free fatty acids (FFAs, lipotoxicity), thapsigargin (ER stress), or rotenone (mitochondrial stress). We then measured [Ca(2+)]i and insulin release in parallel studies. Islets exposed to all stressors except rotenone displayed significantly elevated [Ca(2+)]i in low glucose, however, increased insulin secretion was only observed for 28G due to increased nifedipine-sensitive calcium-channel flux. Following 3-11mM glucose stimulation, all stressors substantially reduced the peak glucose-stimulated [Ca(2+)]i response (first phase). Thapsigargin and cytokines also substantially impacted aspects of calcium influx and ER calcium handling. Stressors did not significantly impact insulin secretion in 11mM glucose for any stressor, although FFAs showed a borderline reduction, which contributed to a significant decrease in the stimulation index (11:3mM glucose) observed for FFAs and also for 28G. We also clamped [Ca(2+)]i using 30mM KCl+250μM diazoxide to test the amplifying pathway. Only rotenone-treated islets showed a robust increase in 3-11mM glucose-stimulated insulin secretion under clamped conditions, suggesting that low-level mitochondrial stress might activate the metabolic amplifying pathway. We conclude that different stressors dissociate [Ca(2+)]i from insulin secretion differently: ER stressors (thapsigargin, cytokines) primarily affect [Ca(2+)]i but not conventional insulin secretion and 'metabolic' stressors (FFAs, 28G, rotenone) impacted insulin secretion. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Novel Zn2+ Modulated GPR39 Receptor Agonists Do Not Drive Acute Insulin Secretion in Rodents.

    Directory of Open Access Journals (Sweden)

    Ola Fjellström

    Full Text Available Type 2 diabetes (T2D occurs when there is insufficient insulin release to control blood glucose, due to insulin resistance and impaired β-cell function. The GPR39 receptor is expressed in metabolic tissues including pancreatic β-cells and has been proposed as a T2D target. Specifically, GPR39 agonists might improve β-cell function leading to more adequate and sustained insulin release and glucose control. The present study aimed to test the hypothesis that GPR39 agonism would improve glucose stimulated insulin secretion in vivo. A high throughput screen, followed by a medicinal chemistry program, identified three novel potent Zn2+ modulated GPR39 agonists. These agonists were evaluated in acute rodent glucose tolerance tests. The results showed a lack of glucose lowering and insulinotropic effects not only in lean mice, but also in diet-induced obese (DIO mice and Zucker fatty rats. It is concluded that Zn2+ modulated GPR39 agonists do not acutely stimulate insulin release in rodents.

  5. OXIDATIVE STRESS: ITS ROLE IN INSULIN SECRETION, HORMONE RECEPTION BY ADIPOCYTES AND LIPOLYSIS IN ADIPOSE TISSUE

    Directory of Open Access Journals (Sweden)

    V. V. Ivanov

    2014-01-01

    Full Text Available Oxidative stress is one of the pathogenetic components of many diseases during which generation of reactive oxigen species increases and the capacity of the antioxidant protection system diminishes. In the research of the last decades special attention has been given to adipose tissue, production of adipokines by it and their role in development of immunoresistance associated with formation of the metabolic syndrome and diabetes.Search for methods of therapeutic correction of adipokine secretion disorders, their influence on metabolism of separate cells and the organism on the whole as well as development of new approaches to correction of disorders in cell sensitivity to insulin are extremely topical nowadays. Systematization and consolidation of accumulated data allow to determine the strategies of further research more accurately; as a result, we have attempted to summarize and analyze the accumulated data on the role of adipose tissue in oxidative stress development.On the basis of literature data and the results of the personal investigations, the role of adipose tissue in forming oxidative stress in diabetes has been analyzed in the article. Brief description of adipose tissue was given as a secretory organ regulating metabolic processes in adipocytes and influencing functions of various organs and systems of the body. Mechanisms of disorder in insulin secretion as well as development of insulin sesistance in type I diabetes were described along with the contribution of lipolysis in adipose tissue to these processes.

  6. Immediate enhancement of first-phase insulin secretion and unchanged glucose effectiveness in patients with type 2 diabetes after Roux-en-Y gastric bypass

    DEFF Research Database (Denmark)

    Martinussen, Christoffer; Bojsen-Moller, Kirstine N; Dirksen, Carsten

    2015-01-01

    effectiveness with Bergman's minimal model. In the fasting state, insulin sensitivity was estimated by HOMA-S and β-cell function by HOMA-β. Moreover, mixed meal tests and OGTTs were performed. In patients with type 2 diabetes, glucose levels normalized after RYGB, first-phase insulin secretion in response...... to iv glucose increased two-fold and HOMA-β improved already 1 week postoperatively, with further enhancements at 3 months. Insulin sensitivity increased in the liver (HOMA-S) at 1 week and at 3 months in peripheral tissues (Si), whereas glucose effectiveness did not improve significantly. During oral...... first-phase insulin secretion to iv glucose and increased HOMA-β. A major role for improved glucose effectiveness after RYGB was not supported by this study....

  7. Observations on the insulin-secretion function in the offsprings of patients with type II diabetes

    International Nuclear Information System (INIS)

    Xu Shujie; Tian Xiaoping; Wu Yan

    2004-01-01

    Objective: To investigate the disturbance of insulin-secretion function in the offsprings of patients with type II diabetes. Methods: Blood sugar (with oxidase method) and insulin (with RIA) levels were measured after overnight fasting and repeatedly measured 2h after 75g glucose per oral in the following subjects: 1) Group A, 23 non-obese offsprings of type II diabetics 2) group B, 18 obese offsprings (BMI ≥25kg/m 2 ) and 3) 27 controls. Homeostatic model assessment-insulin resistance (HOMA-IR) and β-cell function index (HCI) were calculated from the data (glucose and insulin levels) obtained. Results: For Group A subjects, the fasting blood sugar (FPG) levels were significantly higher and HBCI significantly lower than those in te controls (both P<0.05). For Group B obese subjects, in addition to the above two parameters (with HBCI P<0.01), 2h PG levels as well as HOMA-IR were also significantly higher (both P<0.05). Conclusion: Present study showed that in the offsprings of diabetics, HBCI was already lowered before definite impaired glucose tolerance (IGT) could be demonstrated, especially in the obese ones. (authors)

  8. Observations on the insulin-secretion function in the offsprings of patients with type II diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Shujie, Xu; Xiaoping, Tian; Yan, Wu [The First People' s Hospital of Lianyungang (China)

    2004-10-01

    Objective: To investigate the disturbance of insulin-secretion function in the offsprings of patients with type II diabetes. Methods: Blood sugar (with oxidase method) and insulin (with RIA) levels were measured after overnight fasting and repeatedly measured 2h after 75g glucose per oral in the following subjects: 1) Group A, 23 non-obese offsprings of type II diabetics 2) group B, 18 obese offsprings (BMI {>=}25kg/m{sup 2} ) and 3) 27 controls. Homeostatic model assessment-insulin resistance (HOMA-IR) and {beta}-cell function index (HCI) were calculated from the data (glucose and insulin levels) obtained. Results: For Group A subjects, the fasting blood sugar (FPG) levels were significantly higher and HBCI significantly lower than those in te controls (both P<0.05). For Group B obese subjects, in addition to the above two parameters (with HBCI P<0.01), 2h PG levels as well as HOMA-IR were also significantly higher (both P<0.05). Conclusion: Present study showed that in the offsprings of diabetics, HBCI was already lowered before definite impaired glucose tolerance (IGT) could be demonstrated, especially in the obese ones. (authors)

  9. Mitochondrial Pyruvate Carrier 2 Hypomorphism in Mice Leads to Defects in Glucose-Stimulated Insulin Secretion

    Directory of Open Access Journals (Sweden)

    Patrick A. Vigueira

    2014-06-01

    Full Text Available Carrier-facilitated pyruvate transport across the inner mitochondrial membrane plays an essential role in anabolic and catabolic intermediary metabolism. Mitochondrial pyruvate carrier 2 (Mpc2 is believed to be a component of the complex that facilitates mitochondrial pyruvate import. Complete MPC2 deficiency resulted in embryonic lethality in mice. However, a second mouse line expressing an N-terminal truncated MPC2 protein (Mpc2Δ16 was viable but exhibited a reduced capacity for mitochondrial pyruvate oxidation. Metabolic studies demonstrated exaggerated blood lactate concentrations after pyruvate, glucose, or insulin challenge in Mpc2Δ16 mice. Additionally, compared with wild-type controls, Mpc2Δ16 mice exhibited normal insulin sensitivity but elevated blood glucose after bolus pyruvate or glucose injection. This was attributable to reduced glucose-stimulated insulin secretion and was corrected by sulfonylurea KATP channel inhibitor administration. Collectively, these data are consistent with a role for MPC2 in mitochondrial pyruvate import and suggest that Mpc2 deficiency results in defective pancreatic β cell glucose sensing.

  10. Insulin secretion and cellular glucose metabolism after prolonged low-grade intralipid infusion in young men

    DEFF Research Database (Denmark)

    Jensen, Christine B; Storgaard, Heidi; Holst, Jens J

    2003-01-01

    We examined the simultaneous effects of a 24-h low-grade Intralipid infusion on peripheral glucose disposal, intracellular glucose partitioning and insulin secretion rates in twenty young men, by 2-step hyperinsulinemic euglycemic clamp [low insulin clamp (LI), 10 mU/m(2) x min; high insulin clamp...... Intralipid infusion. At LI, glucose oxidation decreased by 10%, whereas glucose disposal, glycolytic flux, glucose storage, and glucose production were not significantly altered. At HI, glucose disposal, and glucose oxidation decreased by 12% and 24%, respectively, during Intralipid infusion. Glycolytic flux......, glucose storage, and glucose production were unchanged. Insulin secretion rates increased in response to Intralipid infusion, but disposition indices (DI = insulin action.insulin secretion) were unchanged. In conclusion, a 24-h low-grade Intralipid infusion caused insulin resistance in the oxidative (but...

  11. Decrease of glucose-induced insulin secretion of rat pancreatic islets after irradiation in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Heinzmann, D; Nadrowitz, R; Besch, W; Schmidt, W; Hahn, H J [Zentralinstitut fuer Diabetes, Karlsburg (German Democratic Republic); Ernst-Moritz-Arndt-Universitaet, Greifswald (German Democratic Republic). Radiologische Klinik)

    1983-01-01

    In vitro irradiation of rat pancreatic islets up to a dose of 2.5 Gy did neither alter glucose- nor isobutylmethyl xanthine (IBMX)-induced insulin secretion. Insulin as well as glucagon content of irradiated islets corresponded to that of the control tissue. So it was in islets irradiated with 25 Gy which were characterized by a decreased insulin secretion in the presence of glucose and IBMX, respectively. There was no indication of an enhanced hormone output in the radiation medium and it is to be suggested that higher radiation doses affect the insulin release of pancreatic islets in vitro. This must be taken into consideration for radioimmunosuppression experiments.

  12. Momordica charantia Administration Improves Insulin Secretion in Type 2 Diabetes Mellitus.

    Science.gov (United States)

    Cortez-Navarrete, Marisol; Martínez-Abundis, Esperanza; Pérez-Rubio, Karina G; González-Ortiz, Manuel; Villar, Miriam Méndez-Del

    2018-02-12

    An improvement in parameters of glycemic control has been observed with Momordica charantia in patients with type 2 diabetes mellitus (T2DM). It is unknown whether this improvement is through a modification of insulin secretion, insulin sensitivity, or both. We hypothesized that M. charantia administration can improve insulin secretion and/or insulin sensitivity in patients with T2DM, without pharmacological treatment. The objective of the study was to evaluate the effect of M. charantia administration on insulin secretion and sensitivity. A randomized, double-blinded, placebo-controlled, clinical trial was carried out in 24 patients who received M. charantia (2000 mg/day) or placebo for 3 months. A 2-h oral glucose tolerance test (OGTT) was done before and after the intervention to calculate areas under the curve (AUC) of glucose and insulin, total insulin secretion (insulinogenic index), first phase of insulin secretion (Stumvoll index), and insulin sensitivity (Matsuda index). In the M. charantia group, there were significant decreases in weight, body mass index (BMI), fat percentage, waist circumference (WC), glycated hemoglobin A1c (A1C), 2-h glucose in OGTT, and AUC of glucose. A significant increase in insulin AUC (56,562 ± 36,078 vs. 65,256 ± 42,720 pmol/L/min, P = .043), in total insulin secretion (0.29 ± 0.18 vs. 0.41 ± 0.29, P = .028), and during the first phase of insulin secretion (557.8 ± 645.6 vs. 1135.7 ± 725.0, P = .043) was observed after M. charantia administration. Insulin sensitivity was not modified with any intervention. In conclusion, M. charantia administration reduced A1C, 2-h glucose, glucose AUC, weight, BMI, fat percentage, and WC, with an increment of insulin AUC, first phase and total insulin secretion.

  13. Common variant in MTNR1B associated with increased risk of type 2 diabetes and impaired early insulin secretion

    DEFF Research Database (Denmark)

    Lyssenko, Valeriya; Nagorny, Cecilia L F; Erdos, Michael R

    2009-01-01

    Genome-wide association studies have shown that variation in MTNR1B (melatonin receptor 1B) is associated with insulin and glucose concentrations. Here we show that the risk genotype of this SNP predicts future type 2 diabetes (T2D) in two large prospective studies. Specifically, the risk genotype...... was associated with impairment of early insulin response to both oral and intravenous glucose and with faster deterioration of insulin secretion over time. We also show that the MTNR1B mRNA is expressed in human islets, and immunocytochemistry confirms that it is primarily localized in beta cells in islets....... Nondiabetic individuals carrying the risk allele and individuals with T2D showed increased expression of the receptor in islets. Insulin release from clonal beta cells in response to glucose was inhibited in the presence of melatonin. These data suggest that the circulating hormone melatonin, which...

  14. Circadian control of insulin secretion is independent of the temporal distribution of feeding

    NARCIS (Netherlands)

    Kalsbeek, Andries; Strubbe, JH

    1998-01-01

    To investigate whether there is a circadian regulation of insulin secretion, rats were adapted to a feeding regimen of six meals equally distributed over 24 h. Under these conditions basal glucose and insulin levels increased during the light phase and decreased during the dark phase. Maximal blood

  15. The influence of GLP-1 on glucose-stimulated insulin secretion

    DEFF Research Database (Denmark)

    Kjems, Lise L; Holst, Jens Juul; Vølund, Aage

    2003-01-01

    . However, the dose-response relationship between GLP-1 and basal and glucose-stimulated prehepatic insulin secretion rate (ISR) is currently not known. Seven patients with type 2 diabetes and seven matched nondiabetic control subjects were studied. ISR was determined during a graded glucose infusion of 2...

  16. Effect of Avocado Soybean Unsaponifiables on Insulin Secretion and Insulin Sensitivity in Patients with Obesity

    Directory of Open Access Journals (Sweden)

    Esperanza Martínez-Abundis

    2013-10-01

    Full Text Available Aim: To evaluate the effect of avocado soybean unsaponifiables (ASU on insulin secretion and insulin sensitivity in patients with obesity. Methods: A randomized, double-blind, placebo-controlled, clinical trial was carried out in 14 obese adult volunteers. After random allocation of the intervention, 7 patients received 300 mg of ASU or placebo during a fasting state for 3 months. A metabolic profile including IL-6 and high-sensitivity C-reactive protein (hs-CRP levels was carried out prior to the intervention. A hyperglycemic-hyperinsulinemic clamp technique was used to assess insulin secretion and insulin sensitivity phases. Mann-Whitney U test and Wilcoxon test were performed for statistical analyses. The study was approved by the local ethics committee of our institution. Results: At baseline, both groups were similar according to clinical and laboratory characteristics. There was no significant difference in insulin secretion and insulin sensitivity with ASU. Conclusions: ASU administration for 3 months did not modify insulin secretion and insulin sensitivity in patients with obesity.

  17. Depressive symptoms, insulin sensitivity and insulin secretion in the RISC cohort study

    NARCIS (Netherlands)

    Bot, M.; Pouwer, F.; de Jonge, P.; Nolan, J.J.; Mari, A.; Højlund, K.; Golay, A.; Balkau, B.; Dekker, J.M.

    2013-01-01

    Aim This study explored the association of depressive symptoms with indices of insulin sensitivity and insulin secretion in a cohort of non-diabetic men and women aged 30 to 64 years. Methods The study population was derived from the 3-year follow-up of the Relationship between Insulin Sensitivity

  18. Depressive symptoms, insulin sensitivity and insulin secretion in the RISC cohort study

    NARCIS (Netherlands)

    Bot, M.; Pouwer, F.; De Jonge, P.; Nolan, J. J.; Mari, A.; Hojlund, K.; Golay, A.; Balkau, B.; Dekker, J. M.

    Aim. This study explored the association of depressive symptoms with indices of insulin sensitivity and insulin secretion in a cohort of non-diabetic men and women aged 30 to 64 years. Methods. The study population was derived from the 3-year follow-up of the Relationship between Insulin Sensitivity

  19. Autocrine effect of Zn²⁺ on the glucose-stimulated insulin secretion.

    Science.gov (United States)

    Slepchenko, Kira G; Daniels, Nigel A; Guo, Aili; Li, Yang V

    2015-09-01

    It is well known that zinc (Zn(2+)) is required for the process of insulin biosynthesis and the maturation of insulin secretory granules in pancreatic beta (β)-cells, and that changes in Zn(2+) levels in the pancreas have been found to be associated with diabetes. Glucose-stimulation causes a rapid co-secretion of Zn(2+) and insulin with similar kinetics. However, we do not know whether Zn(2+) regulates insulin availability and secretion. Here we investigated the effect of Zn(2+) on glucose-stimulated insulin secretion (GSIS) in isolated mouse pancreatic islets. Whereas Zn(2+) alone (control) had no effect on the basal secretion of insulin, it significantly inhibited GSIS. The application of CaEDTA, by removing the secreted Zn(2+) from the extracellular milieu of the islets, resulted in significantly increased GSIS, suggesting an overall inhibitory role of secreted Zn(2+) on GSIS. The inhibitory action of Zn(2+) was mostly mediated through the activities of KATP/Ca(2+) channels. Furthermore, during brief paired-pulse glucose-stimulated Zn(2+) secretion (GSZS), Zn(2+) secretion following the second pulse was significantly attenuated, probably by the secreted endogenous Zn(2+) after the first pulse. Such an inhibition on Zn(2+) secretion following the second pulse was completely reversed by Zn(2+) chelation, suggesting a negative feedback mechanism, in which the initial glucose-stimulated Zn(2+) release inhibits subsequent Zn(2+) secretion, subsequently inhibiting insulin co-secretion as well. Taken together, these data suggest a negative feedback mechanism on GSZS and GSIS by Zn(2+) secreted from β-cells, and the co-secreted Zn(2+) may act as an autocrine inhibitory modulator.

  20. Effect of taurine on the insuline secretion isolated by the pancreatic tissue of intact and irradiated rats

    International Nuclear Information System (INIS)

    Dokshina, G.A.; Silaeva, T.Yu.

    1976-01-01

    The whole-body irradiation of rats (700 rads) inhibits the secretory activity of insular pancreatic tissue. Administration of taurine (200 mg/kg), on the fifth day after irradiation, five times every second day normalizes the secretory function of pancreatic islands. In the experiments in vitro, taurine (1.5 and 3.0 mg/ml) stimulated hormone secretion. The stimulating action of the amino acid manifests itself when β-receptors are blocked by obsidane (0.5 μg/ml). It is suggested that insuline secretion by β-cells of pancreas is restored and enhanced by taurine not merely through the adenylatecyclase system; other ways are also possible

  1. Effect of taurine on the insuline secretion isolated by the pancreatic tissue of intact and irradiated rats

    Energy Technology Data Exchange (ETDEWEB)

    Dokshina, G A; Silaeva, T Yu [Tomskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Biologii i Biofiziki

    1976-05-01

    The whole-body irradiation of rats (700 rads) inhibits the secretory activity of insular pancreatic tissue. Administration of taurine (200 mg/kg), on the fifth day after irradiation, five times every second day normalizes the secretory function of pancreatic islands. In the experiments in vitro, taurine (1.5 and 3.0 mg/ml) stimulated hormone secretion. The stimulating action of the amino acid manifests itself when ..beta..-receptors are blocked by obsidane (0.5 ..mu..g/ml). It is suggested that insuline secretion by ..beta..-cells of pancreas is restored and enhanced by taurine not merely through the adenylatecyclase system; other ways are also possible.

  2. Hormone-sensitive lipase null mice exhibit signs of impaired insulin sensitivity whereas insulin secretion is intact

    DEFF Research Database (Denmark)

    Mulder, Hindrik; Sörhede-Winzell, Maria; Contreras, Juan Antonio

    2003-01-01

    of increased amounts of insulin. Impaired insulin sensitivity was further indicated by retarded glucose disposal during an insulin tolerance test. A euglycemic hyperinsulinemic clamp revealed that hepatic glucose production was insufficiently blocked by insulin in HSL null mice. In vitro, insulin......-stimulated glucose uptake into soleus muscle, and lipogenesis in adipocytes were moderately reduced, suggesting additional sites of insulin resistance. Morphometric analysis of pancreatic islets revealed a doubling of beta-cell mass in HSL null mice, which is consistent with an adaptation to insulin resistance....... Insulin secretion in vitro, examined by perifusion of isolated islets, was not impacted by HSL deficiency. Thus, HSL deficiency results in a moderate impairment of insulin sensitivity in multiple target tissues of the hormone but is compensated by hyperinsulinemia....

  3. An extract from date seeds stimulates endogenous insulin secretion in streptozotocin-induced type I diabetic rats

    Directory of Open Access Journals (Sweden)

    Ahmed F. El Fouhil

    2013-11-01

    Full Text Available Background: The efficacy of an extract from date seeds has been tested successfully on the glycemic control of type I diabetes mellitus in rats. A suggestion that date seed extract could stimulate certain cells to differentiate into insulin-secreting cells has been proposed. In order to investigate such a possibility, this study was conducted to measure C-peptide levels in the serum of type 1 diabetic rats treated with date seed extract. Methods: Two hundred rats were divided into 4 groups. Group I served as the control. Group II was given daily ingestions of 10 ml of date seed extract. Groups III and IV were made diabetic by streptozotocin injection and were given daily subcutaneous injections of 3 IU/day of insulin for 8 weeks. Group IV received, in addition, daily ingestions of 10 ml of seed extract. At the end of experiment, blood samples were collected from each rat, and blood glucose and serum Cpeptide levels were measured. Results: No significant differences in the means of blood glucose and serum C-peptide levels were observed between groups I (control group and II (date seed extract-treated control group. Group IV (date seed extract-insulin-treated diabetic group showed a statistically significant reduction in the mean blood glucose level compared to Group III (insulin-treated diabetic group. The mean serum C-peptide level was significantly higher in group IV compared to group III. Conclusion: Biochemical results suggested an increase in endogenous insulin secretion in the case of type 1 diabetic rats treated with date seed extract, which might be the cause of its hypoglycemic effect.

  4. Complete loss of insulin secretion capacity in type 1A diabetes patients during long-term follow up.

    Science.gov (United States)

    Uno, Sae; Imagawa, Akihisa; Kozawa, Junji; Fukui, Kenji; Iwahashi, Hiromi; Shimomura, Iichiro

    2017-10-16

    Patients with type 1 diabetes are classified into three subtypes in Japan: acute onset, fulminant and slowly progressive. Acute-onset type 1 diabetes would be equivalent to type 1A diabetes, the typical type 1 diabetes in Western countries. The insulin secretion capacity in Japanese patients with long-standing type 1A diabetes is unclear. The aim of the present study was to clarify the course of endogenous insulin secretion during long-term follow up and the factors associated with residual insulin secretion in patients with acute-onset type 1 diabetes (autoimmune). We retrospectively investigated endogenous insulin secretion capacity in 71 patients who fulfilled the diagnostic criteria for acute-onset type 1 diabetes (autoimmune) in Japan. To assess the residual insulin secretion capacity, we evaluated randomly measured C-peptide levels and the results of glucagon stimulation test in 71 patients. In the first year of disease, the child- and adolescent-onset patients had significantly more in residual insulin secretion than the adult-onset patients (34 patients in total). C-peptide levels declined more rapidly in patients whose age of onset was ≤18 years than in patients whose age of onset was ≥19 years. Endogenous insulin secretion capacity stimulated by glucagon was completely lost in almost all patients at >15 years after onset (61 patients in total). Most patients with acute-onset type 1 diabetes (autoimmune) completely lose their endogenous insulin secretion capacity during the disease duration in Japan. Age of onset might affect the course of insulin secretion. © 2017 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.

  5. Differences in glucose-stimulated insulin secretion in vitro of islets from human, nonhuman primate, and porcine origin.

    Science.gov (United States)

    Mueller, Kate R; Balamurugan, A N; Cline, Gary W; Pongratz, Rebecca L; Hooper, Rebecca L; Weegman, Bradley P; Kitzmann, Jennifer P; Taylor, Michael J; Graham, Melanie L; Schuurman, Henk-Jan; Papas, Klearchos K

    2013-01-01

    Porcine islet xenotransplantation is considered a potential cell-based therapy for type 1 diabetes. It is currently being evaluated in diabetic nonhuman primates (NHP) to assess safety and efficacy of the islet product. However, due to a variety of distinct differences between the respective species, including the insulin secretory characteristics of islets, the suitability and predictive value of the preclinical model in the extrapolation to the clinical setting remain a critical issue. Islets isolated from human (n = 3), NHP (n = 2), adult pig (AP, n = 3), and juvenile pig (JP, n = 4) pancreata were perifused with medium at basal glucose (2.5 mm) followed by high glucose (16.7 mm) concentrations. The total glucose-stimulated insulin secretion (GSIS) was calculated from generated insulin secretion profiles. Nonhuman primate islets exhibited GSIS 3-fold higher than AP islets, while AP and JP islets exhibited GSIS 1/3 and 1/30 of human islets, respectively. The insulin content of NHP and AP islets was similar to that of human islets, whereas that of JP islets was 1/5 of human islets. Despite the fact that human, NHP, and AP islets contain similar amounts of insulin, the much higher GSIS for NHP islets than for AP and JP islets suggests the need for increased dosing of islets from JP and AP in pig-to-NHP transplantation. Porcine islet xenotransplantation to humans may require significantly higher dosing given the lower GSIS of AP islets compared to human islets. © 2013 John Wiley & Sons A/S.

  6. Effects of Steaming Time and Frequency for Manufactured Red Liriope platyphylla on the Insulin Secretion Ability and Insulin Receptor Signaling Pathway.

    Science.gov (United States)

    Choi, Sun Il; Lee, Hye Ryun; Goo, Jun Seo; Kim, Ji Eun; Nam, So Hee; Hwang, In Sik; Lee, Young Ju; Prak, So Hae; Lee, Hee Seob; Lee, Jong Sup; Jang, In Surk; Son, Hong Ju; Hwang, Dae Youn

    2011-06-01

    In oriental medicine, Liriope platyphylla (LP) has long been regarded as a curative herb useful for the treatment of diabetes, asthma, and neurodegenerative disorders. The principal objective of this study was to assess the effects of steaming time and frequency for manufactured Red LP (RLP) on insulin secretion ability and insulin receptor signaling pathway. To achieve our goal, several types of LPs manufactured under different conditions were applied to INS cells and streptozotocin (STZ)-induced diabetic ICR mice, after which alterations in insulin concentrations were detected in the culture supernatants and sera. The optimal concentration for the investigation of insulin secretion ability was found to be 50 ug/mL of LP. At this concentration, maximum insulin secretion was observed in the INS cells treated with LP extract steamed for 3 h (3-SLP) with two repeated steps (3 h steaming and 24 h air-dried) carried out 9 times (9-SALP); no significant changes in viability were detected in any of the treated cells. Additionally, the expression and phosphorylation levels of most components in the insulin receptor signaling pathway were increased significantly in the majority of cells treated with steaming-processed LP as compared to the cells treated with LP prepared without steaming. With regard to glucose transporter (GLUT) expression, alterations of steaming time induced similar responses on the expression levels of GLUT-2 and GLUT-3. However, differences in steaming frequency were also shown to induce dose-dependent responses in the expression level of GLUT-2 only; no significant differences in GLUT-3 expression were detected under these conditions. Furthermore, these responses observed in vitro were similarly detected in STZ-induced diabetic mice. 24-SLP and 9-SALP treatment applied for 14 days induced the down-regulation of glucose concentration and upregulation of insulin concentration. Therefore, these results indicated that the steaming processed LP may

  7. Decrease of glucose-induced insulin secretion of pancreatic rat islets after irradiation in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Heinzmann, D; Nadrowitz, R; Besch, W; Schmidt, W; Hahn, H J

    1983-01-01

    Irradiation of pancreatic rat islets up to a dose of 2.5 Gy did neither alter glucose-nor IBMX-induced insulin secretion studied in vitro. The insulin as well as glucagon content of irradiated islets were similar as in the control tissue. This was also true in islets irradiated with 25 Gy which were characterized by a decreased insulin secretion in the presence of glucose and IBMX, respectively. Since we did not find indications of an enhanced hormone output in the radiation medium, we want to suggest that higher irradiation doses affect insulin release of pancreatic islets in vitro. This observation has to be taken into account for application of radioimmunosuppression for transplantation.

  8. Transplantation of insulin-secreting clusters generated from ...

    African Journals Online (AJOL)

    IPCs) generated from mesenchymal stem cells (MSCs) have shown immense potential for therapy. This study aimed to compare the differentiation potential of 2 kinds of MSCs obtained from human bone marrow (BM), and umbilical cord blood ...

  9. Plasma kisspeptin levels are associated with insulin secretion in nondiabetic individuals.

    Directory of Open Access Journals (Sweden)

    Francesco Andreozzi

    Full Text Available To evaluate if plasma kisspeptin concentrations are associated with insulin secretion, as suggested by recent in vitro studies, independently of confounders. 261 nondiabetic subjects were stratified into tertiles according to kisspeptin values. Insulin secretion was assessed using indexes derived from oral glucose tolerance test (OGTT. After adjusting for age, gender, and BMI, subjects in the highest (tertile 3 kisspeptin group exhibited significantly lower values of insulinogenic index, corrected insulin response (CIR30, and Stumvoll indexes for first-phase and second-phase insulin release as compared with low (tertile 1 or intermediate (tertile 2 kisspeptin groups. Univariate correlations between kisspeptin concentration and metabolic variables showed that kisspeptin concentration was significantly and positively correlated with age, blood pressure, and 2-h post-load glucose, and inversely correlated with BMI, and waist circumference. There was an inverse relationship between kisspeptin levels and OGTT-derived indexes of glucose-stimulated insulin secretion. A multivariable regression analysis in a model including all the variables significantly correlated with kisspeptin concentration showed thar age (β = -0.338, P<0.0001, BMI (β = 0.272, P<0.0001, 2-h post-load glucose (β = -0.229, P<0.0001, and kisspeptin (β = -0.105, P = 0.03 remained associated with insulinogenic index. These factors explained 34.6% of the variance of the insulinogenic index. In conclusion, kisspeptin concentrations are associated with insulin secretion independently of important determinants of glucose homeostasis such as gender, age, adiposity, 2-h post-load glucose, and insulin sensitivity.

  10. Mitochondrial GTP Regulates Glucose-Stimulated Insulin Secretion

    OpenAIRE

    Kibbey, Richard G.; Pongratz, Rebecca L.; Romanelli, Anthony J.; Wollheim, Claes B.; Cline, Gary W.; Shulman, Gerald I.

    2007-01-01

    Nucleotide-specific isoforms of the tricarboxylic acid (TCA) cycle enzyme succinyl-CoA synthetase (SCS) catalyze substrate-level synthesis of mitochondrial GTP (mtGTP) and ATP (mtATP). While mtATP yield from glucose metabolism is coupled with oxidative phosphorylation and can vary, each molecule of glucose metabolized within pancreatic beta cells produces approximately one mtGTP, making mtGTP a potentially important fuel signal. In INS-1 832/13 cells and cultured rat islets, siRNA suppression...

  11. Early enhancements of hepatic and later of peripheral insulin sensitivity combined with increased postprandial insulin secretion contribute to improved glycemic control after Roux-en-Y gastric bypass

    DEFF Research Database (Denmark)

    Bojsen-Møller, Kirstine N; Dirksen, Carsten; Jørgensen, Nils Bruun

    2014-01-01

    after RYGB. Participants were included after a preoperative diet induced total weight loss of -9.2±1.2%. Hepatic and peripheral insulin sensitivity were assessed using the hyperinsulinemic euglycemic clamp combined with glucose tracer technique and beta-cell function evaluated in response...... after surgery. Insulin mediated glucose disposal and suppression of fatty acids did not improve immediately after surgery but increased at 3 months and 1 year likely related to the reduction in body weight. Insulin secretion increased after RYGB, but only in patients with type 2 diabetes and only...

  12. Protein malnutrition blunts the increment of taurine transporter expression by a high-fat diet and impairs taurine reestablishment of insulin secretion.

    Science.gov (United States)

    Branco, Renato Chaves Souto; Camargo, Rafael Ludemann; Batista, Thiago Martins; Vettorazzi, Jean Franciesco; Borck, Patrícia Cristine; Dos Santos-Silva, Junia Carolina Rebelo; Boschero, Antonio Carlos; Zoppi, Cláudio Cesar; Carneiro, Everardo Magalhães

    2017-09-01

    Taurine (Tau) restores β-cell function in obesity; however, its action is lost in malnourished obese rodents. Here, we investigated the mechanisms involved in the lack of effects of Tau in this model. C57BL/6 mice were fed a control diet (CD) (14% protein) or a protein-restricted diet (RD) (6% protein) for 6 wk. Afterward, mice received a high-fat diet (HFD) for 8 wk [CD + HFD (CH) and RD + HFD (RH)] with or without 5% Tau supplementation after weaning on their drinking water [CH + Tau (CHT) and RH + Tau (RHT)]. The HFD increased insulin secretion through mitochondrial metabolism in CH and RH. Tau prevented all those alterations in CHT only. The expression of the taurine transporter (Tau-T), as well as Tau content in pancreatic islets, was increased in CH but had no effect on RH. Protein malnutrition programs β cells and impairs Tau-induced restoration of mitochondrial metabolism and biogenesis. This may be associated with modulation of the expression of Tau-T in pancreatic islets, which may be responsible for the absence of effect of Tau in protein-malnourished obese mice.-Branco, R. C. S., Camargo, R. L., Batista, T. M., Vettorazzi, J. F., Borck, P. C., dos Santos-Silva, J. C. R., Boschero, A. C., Zoppi, C. C., Carneiro, E. M. Protein malnutrition blunts the increment of taurine transporter expression by a high-fat diet and impairs taurine reestablishment of insulin secretion. © FASEB.

  13. Intra- and Inter-islet Synchronization of Metabolically Driven Insulin Secretion

    DEFF Research Database (Denmark)

    Pedersen, Morten Gram; Bertram, Richard; Sherman, Arthur

    2005-01-01

    mechanisms for intra-islet and inter-islet synchronization. We show that electrical coupling is sufficient to synchronize both electrical bursting activity and metabolic oscillations. We also demonstrate that islets can synchronize by mutually entraining each other by their effects on a simple model "liver......,'' which responds to the level of insulin secretion by adjusting the blood glucose concentration in an appropriate way. Since all islets are exposed to the blood, the distributed islet-liver system can synchronize the individual islet insulin oscillations. Thus, we demonstrate how intra-islet and inter...

  14. Insulin secretion and cellular glucose metabolism after prolonged low-grade intralipid infusion in young men

    DEFF Research Database (Denmark)

    Jensen, Christine B; Storgaard, Heidi; Holst, Jens Juul

    2003-01-01

    not in the nonoxidative) glucose metabolism in young healthy men. Moreover, insulin hypersecretion perfectly countered the free-fatty acid-induced insulin resistance. Future studies are needed to determine the role of a prolonged moderate lipid load in subjects at increased risk of developing diabetes.......We examined the simultaneous effects of a 24-h low-grade Intralipid infusion on peripheral glucose disposal, intracellular glucose partitioning and insulin secretion rates in twenty young men, by 2-step hyperinsulinemic euglycemic clamp [low insulin clamp (LI), 10 mU/m(2) x min; high insulin clamp...

  15. Effects of GCK, GCKR, G6PC2 and MTNR1B variants on glucose metabolism and insulin secretion.

    Directory of Open Access Journals (Sweden)

    Cheng Hu

    Full Text Available BACKGROUND: Single nucleotide polymorphisms (SNPs from GCK, GCKR, G6PC2 and MTNR1B were found to modulate the fasting glucose levels. The current study aimed to replicate this association in the Chinese population and further analyze their effects on biphasic insulin secretion. METHODS/PRINCIPAL FINDINGS: SNPs from GCK, GCKR, G6PC2 and MTNR1B were genotyped in the Shanghai Chinese, including 3,410 type 2 diabetes patients and 3,412 controls. The controls were extensively phenotyped for the traits related to glucose metabolism and insulin secretion. We replicated the association between GCK rs1799884, G6PC2 rs16856187 and MTNR1B rs10830963 and fasting glucose in our samples (p = 0.0003-2.0x10(-8. GCK rs1799884 and G6PC2 rs16856187 showed association to HOMA-beta, insulinogenic index and both first- and second-phases insulin secretion (p = 0.0030-0.0396. MTNR1B rs10830963 was associated to HOMA-beta, insulinogenic index and first-phase insulin secretion (p = 0.0102-0.0426, but not second-phase insulin secretion (p = 0.9933. Combined effect analyses showed individuals carrying more risk allele for high fasting glucose tended to have a higher glucose levels at both fasting and 2 h during OGTTs (p = 1.7x10(-13 and 0.0009, respectively, as well as lower HOMA-beta, insulinogenic index and both first- and second-phases insulin secretion (p = 0.0321-1.1x10(-7. CONCLUSIONS/SIGNIFICANCE: We showed that SNPs from GCK, G6PC2 and MTNR1B modulated the fasting glucose levels in the normoglycaemic population while SNPs from G6PC2 and GCKR was associated with type 2 diabetes. Moreover, we found GCK and G6PC2 genetic variants were associated to both first- and second-phases insulin secretion while MTNR1B genetic variant was associated with first-phase insulin secretion, but not second-phase insulin secretion.

  16. Shared Genetic Control of Brain Activity During Sleep and Insulin Secretion: A Laboratory-Based Family Study.

    Science.gov (United States)

    Morselli, Lisa L; Gamazon, Eric R; Tasali, Esra; Cox, Nancy J; Van Cauter, Eve; Davis, Lea K

    2018-01-01

    Over the past 20 years, a large body of experimental and epidemiologic evidence has linked sleep duration and quality to glucose homeostasis, although the mechanistic pathways remain unclear. The aim of the current study was to determine whether genetic variation influencing both sleep and glucose regulation could underlie their functional relationship. We hypothesized that the genetic regulation of electroencephalographic (EEG) activity during non-rapid eye movement sleep, a highly heritable trait with fingerprint reproducibility, is correlated with the genetic control of metabolic traits including insulin sensitivity and β-cell function. We tested our hypotheses through univariate and bivariate heritability analyses in a three-generation pedigree with in-depth phenotyping of both sleep EEG and metabolic traits in 48 family members. Our analyses accounted for age, sex, adiposity, and the use of psychoactive medications. In univariate analyses, we found significant heritability for measures of fasting insulin sensitivity and β-cell function, for time spent in slow-wave sleep, and for EEG spectral power in the delta, theta, and sigma ranges. Bivariate heritability analyses provided the first evidence for a shared genetic control of brain activity during deep sleep and fasting insulin secretion rate. © 2017 by the American Diabetes Association.

  17. High Serum Advanced Glycation End Products Are Associated with Decreased Insulin Secretion in Patients with Type 2 Diabetes: A Brief Report

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Okura

    2017-01-01

    Full Text Available Objective. Advanced glycation end products (AGEs are important in the pathophysiology of type 2 diabetes mellitus (T2DM. They directly cause insulin secretory defects in animal and cell culture models and may promote insulin resistance in nondiabetic subjects. We have developed a highly sensitive liquid chromatography-tandem mass spectrometry method for measuring AGEs in human serum. Here, we use this method to investigate the relationship between AGEs and insulin secretion and resistance in patients with T2DM. Methods. Our study involved 15 participants with T2DM not on medication and 20 nondiabetic healthy participants. We measured the AGE carboxyethyllysine (CEL, carboxymethyllysine (CML, and methyl-glyoxal-hydro-imidazolone (MG-H1. Plasma glucose and insulin were measured in these participants during a meal tolerance test, and the glucose disposal rate was measured during a euglycemic-hyperinsulinemic clamp. Results. CML and CEL levels were significantly higher in T2DM than non-DM participants. CML showed a significant negative correlation with insulin secretion, HOMA-%B, and a significant positive correlation with the insulin sensitivity index in T2DM participants. There was no correlation between any of the AGEs measured and glucose disposal rate. Conclusions. These results suggest that AGE might play a role in the development or prediction of insulin secretory defects in type 2 diabetes.

  18. Effect of Magnesium Supplements on Insulin Secretion After Kidney Transplantation: A Randomized Controlled Trial.

    Science.gov (United States)

    Van Laecke, Steven; Caluwe, Rogier; Huybrechts, Inge; Nagler, Evi V; Vanholder, Raymond; Peeters, Patrick; Van Vlem, Bruno; Van Biesen, Wim

    2017-08-29

    BACKGROUND Hypomagnesemia is associated with a disturbed glucose metabolism. Insulin hypo-secretion predicts diabetes in the general population and in transplant recipients. We aimed to assess whether magnesium improves insulin secretion and glycemic control after transplantation in prevalent hypomagnesemic kidney transplant recipients. MATERIAL AND METHODS We conducted an open-label, randomized, parallel-group study. Eligible participants were adults more than 4 months after kidney transplantation on tacrolimus with persisting serum magnesium concentrations food-frequency questionnaire. All analyses were done on an intention-to-treat basis. RESULTS Magnesium with a mean daily dose of 688±237mg in the treatment group failed to lead to significant differences between the 2 groups in FPIR, fasting glucose, HbA1c, or HOMA-IR. Persisting hypomagnesemia was very common and associated with more insulin hypo-secretion, glucose intolerance, and lower dietary magnesium intake (142±56 versus 202±90 mg; p=0.015) as compared to patients with a rise in serum magnesium over 6 months. CONCLUSIONS Magnesium supplementation does not improve insulin secretion in stable hypomagnesemic kidney transplant recipients on tacrolimus. Persisting hypomagnesemia is associated with impaired glucose tolerance, insulin hypo-secretion, and dietary factors.

  19. Host Genotype and Gut Microbiome Modulate Insulin Secretion and Diet-Induced Metabolic Phenotypes.

    Science.gov (United States)

    Kreznar, Julia H; Keller, Mark P; Traeger, Lindsay L; Rabaglia, Mary E; Schueler, Kathryn L; Stapleton, Donald S; Zhao, Wen; Vivas, Eugenio I; Yandell, Brian S; Broman, Aimee Teo; Hagenbuch, Bruno; Attie, Alan D; Rey, Federico E

    2017-02-14

    Genetic variation drives phenotypic diversity and influences the predisposition to metabolic disease. Here, we characterize the metabolic phenotypes of eight genetically distinct inbred mouse strains in response to a high-fat/high-sucrose diet. We found significant variation in diabetes-related phenotypes and gut microbiota composition among the different mouse strains in response to the dietary challenge and identified taxa associated with these traits. Follow-up microbiota transplant experiments showed that altering the composition of the gut microbiota modifies strain-specific susceptibility to diet-induced metabolic disease. Animals harboring microbial communities with enhanced capacity for processing dietary sugars and for generating hydrophobic bile acids showed increased susceptibility to metabolic disease. Notably, differences in glucose-stimulated insulin secretion between different mouse strains were partially recapitulated via gut microbiota transfer. Our results suggest that the gut microbiome contributes to the genetic and phenotypic diversity observed among mouse strains and provide a link between the gut microbiome and insulin secretion. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  20. Insulin secretion and insulin action in non-insulin-dependent diabetes mellitus: which defect is primary?

    Science.gov (United States)

    Reaven, G M

    1984-01-01

    Defects in both insulin secretion and insulin action exist in patients with non-insulin-dependent diabetes mellitus (NIDDM). The loss of the acute plasma insulin response to intravenous glucose is seen in patients with relatively mild degrees of fasting hyperglycemia, but patients with severe fasting hyperglycemia also demonstrate absolute hypoinsulinemia in response to an oral glucose challenge. In contrast, day-long circulating insulin levels are within normal limits even in severely hyperglycemic patients with NIDDM. The relationship between NIDDM and insulin action in NIDDM is less complex, and is a characteristic feature of the syndrome. This metabolic defect is independent of obesity, and the severity of the resistance to insulin-stimulated glucose uptake increases with magnitude of hyperglycemia. Control of hyperglycemia with exogenous insulin ameliorates the degree of insulin resistance, and reduction of insulin resistance with weight loss in obese patients with NIDDM leads to an enhanced insulin response. Since neither therapeutic intervention is capable of restoring all metabolic abnormalities to normal, these observations do not tell us which of these two defects is primarily responsible for the development of NIDDM. Similarly, the observation that most patients with impaired glucose tolerance are hyperinsulinemic and insulin resistant does not prove that insulin resistance is the primary defect in NIDDM. In conclusion, reduction in both insulin secretion and action is seen in patients with NIDDM, and the relationship between these two metabolic abnormalities is very complex.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Insulin secretion and incretin hormones after oral glucose in non-obese subjects with impaired glucose tolerance

    DEFF Research Database (Denmark)

    Rask, E; Olsson, T; Söderberg, S

    2004-01-01

    of glucose, insulin, C-peptide, GLP-1, and GIP. Insulin secretion (TIS) and insulin sensitivity (OGIS) were assessed using models describing the relationship between glucose, insulin and C-peptide data. These models allowed estimation also of the hepatic extraction of insulin. The age (54.2 +/- 9.7 [mean......Subjects with impaired glucose tolerance (IGT) are usually overweight and exhibit insulin resistance with a defective compensation of insulin secretion. In this study, we sought to establish the interrelation between insulin secretion and insulin sensitivity after oral glucose in non-obese subjects...... over the whole 180-minute period was higher in IGT (26.2 +/- 2.4 v 20.0 +/- 2.0 nmol/L; P =.035). Hepatic insulin extraction correlated linearly with OGIS (r = 0.71; P

  2. Endocrine determinants of changes in insulin sensitivity and insulin secretion during a weight cycle in healthy men.

    Directory of Open Access Journals (Sweden)

    Judith Karschin

    Full Text Available Changes in insulin sensitivity (IS and insulin secretion occur with perturbations in energy balance and glycemic load (GL of the diet that may precede the development of insulin resistance and hyperinsulinemia. Determinants of changes in IS and insulin secretion with weight cycling in non-obese healthy subjects remain unclear.In a 6wk controlled 2-stage randomized dietary intervention 32 healthy men (26±4y, BMI: 24±2kg/m2 followed 1wk of overfeeding (OF, 3wks of caloric restriction (CR containing either 50% or 65% carbohydrate (CHO and 2wks of refeeding (RF with the same amount of CHO but either low or high glycaemic index at ±50% energy requirement. Measures of IS (basal: HOMA-index, postprandial: Matsuda-ISI, insulin secretion (early: Stumvoll-index, total: tAUC-insulin/tAUC-glucose and potential endocrine determinants (ghrelin, leptin, adiponectin, thyroid hormone levels, 24h-urinary catecholamine excretion were assessed.IS improved and insulin secretion decreased due to CR and normalized upon RF. Weight loss-induced improvements in basal and postprandial IS were associated with decreases in leptin and increases in ghrelin levels, respectively (r = 0.36 and r = 0.62, p<0.05. Weight regain-induced decrease in postprandial IS correlated with increases in adiponectin, fT3, TSH, GL of the diet and a decrease in ghrelin levels (r-values between -0.40 and 0.83, p<0.05 whereas increases in early and total insulin secretion were associated with a decrease in leptin/adiponectin-ratio (r = -0.52 and r = -0.46, p<0.05 and a decrease in fT4 (r = -0.38, p<0.05 for total insulin secretion only. After controlling for GL associations between RF-induced decrease in postprandial IS and increases in fT3 and TSH levels were no longer significant.Weight cycling induced changes in IS and insulin secretion were associated with changes in all measured hormones, except for catecholamine excretion. While leptin, adiponectin and ghrelin seem to be the major

  3. A Genome-Wide Association Study of IVGTT-Based Measures of First Phase Insulin Secretion Refines the Underlying Physiology of Type 2 Diabetes Variants

    DEFF Research Database (Denmark)

    Wood, Andrew R; Jonsson, Anna; Jackson, Anne U

    2017-01-01

    Understanding the physiological mechanisms by which common variants predispose to type 2 diabetes requires large studies with detailed measures of insulin secretion and sensitivity. Here we performed the largest genome-wide association study of first-phase insulin secretion, as measured by intrav...

  4. Effects of 12 weeks' treatment with a proton pump inhibitor on insulin secretion, glucose metabolism and markers of cardiovascular risk in patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Hove, K D; Brøns, Charlotte; Færch, Kai Erik Vinther

    2013-01-01

    Recent studies suggest that proton pump inhibitor treatment may increase insulin secretion and improve glucose metabolism in type 2 diabetes. In a randomised double-blind prospective placebo-controlled 2 × 2 factorial study, we examined the effect of esomeprazole on insulin secretion, HbA(1c...

  5. Combined lipidomic and proteomic analysis of isolated human islets exposed to palmitate reveals time-dependent changes in insulin secretion and lipid metabolism.

    Directory of Open Access Journals (Sweden)

    Kirsten Roomp

    Full Text Available Studies on the pathophysiology of type 2 diabetes mellitus (T2DM have linked the accumulation of lipid metabolites to the development of beta-cell dysfunction and impaired insulin secretion. In most in vitro models of T2DM, rodent islets or beta-cell lines are used and typically focus is on specific cellular pathways or organs. Our aim was to, firstly, develop a combined lipidomics and proteomics approach for lipotoxicity in isolated human islets and, secondly, investigate if the approach could delineate novel and/ or confirm reported mechanisms of lipotoxicity. To this end isolated human pancreatic islets, exposed to chronically elevated palmitate concentrations for 0, 2 and 7 days, were functionally characterized and their levels of multiple targeted lipid and untargeted protein species determined. Glucose-stimulated insulin secretion from the islets increased on day 2 and decreased on day 7. At day 7 islet insulin content decreased and the proinsulin to insulin content ratio doubled. Amounts of cholesterol, stearic acid, C16 dihydroceramide and C24:1 sphingomyelin, obtained from the lipidomic screen, increased time-dependently in the palmitate-exposed islets. The proteomic screen identified matching changes in proteins involved in lipid biosynthesis indicating up-regulated cholesterol and lipid biosynthesis in the islets. Furthermore, proteins associated with immature secretory granules were decreased when palmitate exposure time was increased despite their high affinity for cholesterol. Proteins associated with mature secretory granules remained unchanged. Pathway analysis based on the protein and lipid expression profiles implicated autocrine effects of insulin in lipotoxicity. Taken together the study demonstrates that combining different omics approaches has potential in mapping of multiple simultaneous cellular events. However, it also shows that challenges exist for effectively combining lipidomics and proteomics in primary cells. Our

  6. Impaired Sympathoadrenal Axis Function Contributes to Enhanced Insulin Secretion in Prediabetic Obese Rats

    Directory of Open Access Journals (Sweden)

    Ana Eliza Andreazzi

    2011-01-01

    Full Text Available The involvement of sympathoadrenal axis activity in obesity onset was investigated using the experimental model of treating neonatal rats with monosodium L-glutamate. To access general sympathetic nervous system activity, we recorded the firing rates of sympathetic superior cervical ganglion nerves in animals. Catecholamine content and secretion from isolated adrenal medulla were measured. Intravenous glucose tolerance test was performed, and isolated pancreatic islets were stimulated with glucose and adrenergic agonists. The nerve firing rate of obese rats was decreased compared to the rate for lean rats. Basal catecholamine secretion decreased whereas catecholamine secretion induced by carbachol, elevated extracellular potassium, and caffeine in the isolated adrenal medulla were all increased in obese rats compared to control. Both glucose intolerance and hyperinsulinaemia were observed in obese rats. Adrenaline strongly inhibited glucose-induced insulin secretion in obese animals. These findings suggest that low sympathoadrenal activity contributes to impaired glycaemic control in prediabetic obese rats.

  7. Studies on insulin secretion and insulin resistance in non-insulin-dependent diabetes in young Indians

    International Nuclear Information System (INIS)

    Naidoo, C.

    1986-01-01

    Patients with Non-insulin-dependent diabetes mellitus (NIDDM) have defects in insulin secretion and insulin action. In the discrete genetic syndrome of NIDDY (non-insulin-dependent diabetes in the young), the situation is less clear and these aspects is the subject of this thesis. This study included Indian pasients with three generation transmission of NIDDM via one parent. The insulin and C-peptide responses to oral and intravenous glucose in patients with NIDDY were studied. The insulin and glucose responses to non-glucose secretogogues glucagon, tolbutamide and arginine, in NIDDY were also investigated. The following aspects with regard to insulin resistance in NIDDY were examined: glucose and free fatty acid response to intravenous insulin administration, insulin binding to circulating erythrocytes and monocytes, 125 I-insulin binding to the solubilized erythrocyte membrane receptor and 125 I-insulin binding to fibroblasts in culture

  8. LPS-Enhanced Glucose-Stimulated Insulin Secretion Is Normalized by Resveratrol

    DEFF Research Database (Denmark)

    Nøhr, Mark K; Dudele, Anete; Poulsen, Morten M

    2016-01-01

    we test the effect of LPS and the anti-inflammatory compound resveratrol on glucose homeostasis, insulin levels and inflammation. Mice were subcutaneously implanted with osmotic mini pumps infusing either low-dose LPS or saline for 28 days. Half of the mice were treated with resveratrol delivered...... through the diet. LPS caused increased inflammation of the liver and adipose tissue (epididymal and subcutaneous) together with enlarged spleens and increased number of leukocytes in the blood. Resveratrol specifically reduced the inflammatory status in epididymal fat (reduced expression of TNFa and Il1b......, whereas the increased macrophage infiltration was unaltered) without affecting the other tissues investigated. By LC-MS, we were able to quantitate resveratrol metabolites in epididymal but not subcutaneous adipose tissue. LPS induced insulin resistance as the glucose-stimulated insulin secretion during...

  9. Intake of Lactobacillus reuteri Improves Incretin and Insulin Secretion in Glucose-Tolerant Humans

    DEFF Research Database (Denmark)

    Simon, Marie-Christine; Strassburger, Klaus; Nowotny, Bettina

    2015-01-01

    production. Muscle and hepatic lipid contents were assessed by (1)H-magnetic resonance spectroscopy, and immune status, cytokines, and endotoxin were measured with specific assays. RESULTS: In glucose-tolerant volunteers, daily administration of L. reuteri SD5865 increased glucose-stimulated GLP-1 and GLP-2....... reuteri SD5865 or placebo over 4 weeks. Oral glucose tolerance and isoglycemic glucose infusion tests were used to assess incretin effect and GLP-1 and GLP-2 secretion, and euglycemic-hyperinsulinemic clamps with [6,6-(2)H2]glucose were used to measure peripheral insulin sensitivity and endogenous glucose...... cytokines. CONCLUSIONS: Enrichment of gut microbiota with L. reuteri increases insulin secretion, possibly due to augmented incretin release, but does not directly affect insulin sensitivity or body fat distribution. This suggests that oral ingestion of one specific strain may serve as a novel therapeutic...

  10. Significance of glucagon for insulin secretion and hepatic glycogenolysis during exercise in rats

    DEFF Research Database (Denmark)

    Richter, Erik; Galbo, H; Holst, J J

    1981-01-01

    The significance of glucagon and of the sympatho-adrenal system for insulin secretion and hepatic glycogen depletion during exercise was studied. Male rats were either adrenodemedullated and chemically sympathectomized with 6-hydroxydopamine (SX) or sham-treated (C). During light ether anesthesia......, cardiac blood for glucose analysis and a biopsy of the liver were obtained, and either antigen-stripped glucagon antibodies (A) or control gamma globulins (N) in saline were injected through the cardiac cannula. Subsequently, the rats swam in tepid water (33-34 degree C) for 100 minutes with a tail weight...... attached (2% of body weight). Then cardiac blood was drawn for analysis of glucose, insulin and glucagon, and a sample of the liver was collected. In both CA and CN rats, the blood glucose concentration tended to increase (p less than 0.1) during exercise, whereas hepatic glycogen depletion and the plasma...

  11. Studies on insulin secretion and insulin resistance in non-insulin-dependent diabetes in young Indians

    Energy Technology Data Exchange (ETDEWEB)

    Naidoo, C

    1986-01-01

    Patients with Non-insulin-dependent diabetes mellitus (NIDDM) have defects in insulin secretion and insulin action. In the discrete genetic syndrome of NIDDY (non-insulin-dependent diabetes in the young), the situation is less clear and these aspects is the subject of this thesis. This study included Indian pasients with three generation transmission of NIDDM via one parent. The insulin and C-peptide responses to oral and intravenous glucose in patients with NIDDY were studied. The insulin and glucose responses to non-glucose secretogogues glucagon, tolbutamide and arginine, in NIDDY were also investigated. The following aspects with regard to insulin resistance in NIDDY were examined: glucose and free fatty acid response to intravenous insulin administration, insulin binding to circulating erythrocytes and monocytes, /sup 125/I-insulin binding to the solubilized erythrocyte membrane receptor and /sup 125/I-insulin binding to fibroblasts in culture.

  12. Deletion of GPR40 Impairs Glucose-Induced Insulin Secretion In Vivo in Mice Without Affecting Intracellular Fuel Metabolism in Islets

    Energy Technology Data Exchange (ETDEWEB)

    Alquier, Thierry; Peyot, Marie-Line; Latour, M. G.; Kebede, Melkam; Sorensen, Christina M.; Gesta, Stephane; Kahn, C. R.; Smith, Richard D.; Jetton, Thomas L.; Metz, Thomas O.; Prentki, Marc; Poitout, Vincent J.

    2009-11-01

    The G protein-coupled receptor GPR40 mediates fatty-acid potentiation of glucose-stimulated insulin secretion, but its contribution to insulin secretion in vivo and mechanisms of action remain uncertain. This study was aimed to ascertain whether GPR40 controls insulin secretion in vivo and modulates intracellular fuel metabolism in islets. We observed that glucose- and arginine-stimulated insulin secretion, assessed by hyperglycemic clamps, was decreased by approximately 60% in GPR40 knock-out (KO) fasted and fed mice, without changes in insulin sensitivity assessed by hyperinsulinemic-euglycemic clamps. Glucose and palmitate metabolism were not affected by GPR40 deletion. Lipid profiling revealed a similar increase in triglyceride and decrease in lysophosphatidylethanolamine species in WT and KO islets in response to palmitate. These results demonstrate that GPR40 regulates insulin secretion in vivo not only in response to fatty acids but also to glucose and arginine, without altering intracellular fuel metabolism.

  13. Dietary Sodium Restriction Decreases Insulin Secretion Without Affecting Insulin Sensitivity in Humans

    Science.gov (United States)

    Byrne, Loretta M.; Yu, Chang; Wang, Thomas J.; Brown, Nancy J.

    2014-01-01

    Context: Interruption of the renin-angiotensin-aldosterone system prevents incident diabetes in high-risk individuals, although the mechanism remains unclear. Objective: To test the hypothesis that activation of the endogenous renin-angiotensin-aldosterone system or exogenous aldosterone impairs insulin secretion in humans. Design: We conducted a randomized, blinded crossover study of aldosterone vs vehicle and compared the effects of a low-sodium versus a high-sodium diet. Setting: Academic clinical research center. Participants: Healthy, nondiabetic, normotensive volunteers. Interventions: Infusion of exogenous aldosterone (0.7 μg/kg/h for 12.5 h) or vehicle during low or high sodium intake. Low sodium (20 mmol/d; n = 12) vs high sodium (160 mmol/d; n = 17) intake for 5–7 days. Main Outcome Measures: Change in acute insulin secretory response assessed during hyperglycemic clamps while in sodium balance during a low-sodium vs high-sodium diet during aldosterone vs vehicle. Results: A low-sodium diet increased endogenous aldosterone and plasma renin activity, and acute glucose-stimulated insulin (−16.0 ± 5.6%; P = .007) and C-peptide responses (−21.8 ± 8.4%; P = .014) were decreased, whereas the insulin sensitivity index was unchanged (−1.0 ± 10.7%; P = .98). Aldosterone infusion did not affect the acute insulin response (+1.8 ± 4.8%; P = .72) or insulin sensitivity index (+2.0 ± 8.8%; P = .78). Systolic blood pressure and serum potassium were similar during low and high sodium intake and during aldosterone infusion. Conclusions: Low dietary sodium intake reduces insulin secretion in humans, independent of insulin sensitivity. PMID:25029426

  14. Insulin Secretion and Incretin Hormone Concentration in Women with Previous Gestational Diabetes Mellitus

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    Sung Hoon Yu

    2011-02-01

    Full Text Available BackgroundWe examined the change in the levels of incretin hormone and effects of glucose-dependent insulinotropic polypeptide (GIP and glucagon-like peptide 1 (GLP-1 on insulin secretion in women with previous gestational diabetes (pGDM.MethodsA 75-g oral glucose tolerance test (OGTT was conducted on 34 women with pGDM. In addition, 11 women with normal glucose tolerance, matched for age, height and weight, were also tested. The insulin, GIP, GLP-1, and glucagon concentrations were measured, and their anthropometric and biochemical markers were also measured.ResultsAmong 34 women with pGDM, 18 had normal glucose tolerance, 13 had impaired glucose tolerance (IGT and 1 had diabetes. No significant differences were found in GLP-1 concentration between the pGDM and control group. However, a significantly high level of glucagon was present in the pGDM group at 30 minutes into the OGTT. The GIP concentration was elevated at 30 minutes and 60 minutes in the pGDM group. With the exception of the 30-minute timepoint, women with IGT had significantly high blood glucose from 0 to 120 minutes. However, there was no significant difference in insulin or GLP-1 concentration. The GIP level was significantly high from 0 to 90 minutes in patients diagnosed with IGT.ConclusionGLP-1 secretion does not differ between pGDM patients and normal women. GIP was elevated, but that does not seem to induce in increase in insulin secretion. Therefore, we conclude that other factors such as heredity and environment play important roles in the development of type 2 diabetes.

  15. Insulin Secretion and Risk for Future Diabetes in Subjects with a Nonpositive Insulinogenic Index

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    Daisuke Aono

    2018-01-01

    Full Text Available Aim. To characterize subjects with a nonpositive insulinogenic index and longitudinally observe changes in their glucose tolerance. Subjects and Methods. A historical cohort study was conducted using data from the medical checkups of public school workers. Indices of insulin secretion and insulin sensitivity derived from oral glucose tolerance test (OGTT and the incidences of diabetes and impaired glucose tolerance (IGT were compared among subgroups of subjects with different insulinogenic index (change in insulin/change in glucose over the first 30 min on the OGTT. Results. Of the 1464 nondiabetic subjects at baseline, 72 (4.9% subjects had a nonpositive insulinogenic index: 42 of those subjects had a nonpositive glucose response (ΔGlu0–30 ≤ 0 and 30 had a nonpositive insulin response (ΔIns0–30 ≤ 0. Compared with subjects who had normal glucose tolerance (NGT with insulinogenic index ≥ 0.4, subjects with a nonpositive glucose response had a higher first-phase Stumvoll and lower incidences of diabetes and IGT based on a log-rank test (p<0.05, whereas subjects with a nonpositive insulin response had lower indices of insulin secretion and a higher incidence of diabetes (p<0.05. Conclusions. These results demonstrate that in the first 30 min on the OGTT, subjects with a nonpositive insulinogenic index due to a nonpositive glucose response (ΔGlu0–30 ≤ 0 had a lower risk for future diabetes and that subjects with nonpositive insulin response (ΔIns0–30 ≤ 0 had a higher risk for future one.

  16. Glutathione peroxidase mimic ebselen improves glucose-stimulated insulin secretion in murine islets.

    Science.gov (United States)

    Wang, Xinhui; Yun, Jun-Won; Lei, Xin Gen

    2014-01-10

    Glutathione peroxidase (GPX) mimic ebselen and superoxide dismutase (SOD) mimic copper diisopropylsalicylate (CuDIPs) were used to rescue impaired glucose-stimulated insulin secretion (GSIS) in islets of GPX1 and(or) SOD1-knockout mice. Ebselen improved GSIS in islets of all four tested genotypes. The rescue in the GPX1 knockout resulted from a coordinated transcriptional regulation of four key GSIS regulators and was mediated by the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α)-mediated signaling pathways. In contrast, CuDIPs improved GSIS only in the SOD1 knockout and suppressed gene expression of the PGC-1α pathway. Islets from the GPX1 and(or) SOD1 knockout mice provided metabolically controlled intracellular hydrogen peroxide (H2O2) and superoxide conditions for the present study to avoid confounding effects. Bioinformatics analyses of gene promoters and expression profiles guided the search for upstream signaling pathways to link the ebselen-initiated H2O2 scavenging to downstream key events of GSIS. The RNA interference was applied to prove PGC-1α as the main mediator for that link. Our study revealed a novel metabolic use and clinical potential of ebselen in rescuing GSIS in the GPX1-deficient islets and mice, along with distinct differences between the GPX and SOD mimics in this regard. These findings highlight the necessities and opportunities of discretional applications of various antioxidant enzyme mimics in treating insulin secretion disorders. REBOUND TRACK: This work was rejected during standard peer review and rescued by Rebound Peer Review (Antioxid Redox Signal 16: 293-296, 2012) with the following serving as open reviewers: Regina Brigelius-Flohe, Vadim Gladyshev, Dexing Hou, and Holger Steinbrenner.

  17. Effect of Artemisia dracunculus Administration on Glycemic Control, Insulin Sensitivity, and Insulin Secretion in Patients with Impaired Glucose Tolerance.

    Science.gov (United States)

    Méndez-Del Villar, Miriam; Puebla-Pérez, Ana M; Sánchez-Peña, María J; González-Ortiz, Luis J; Martínez-Abundis, Esperanza; González-Ortiz, Manuel

    2016-05-01

    To evaluate the effect of Artemisia dracunculus on glycemic control, insulin sensitivity, and insulin secretion in patients with impaired glucose tolerance (IGT). A randomized, double blind, placebo-controlled clinical trial was performed in 24 patients with diagnosis of IGT. Before and after the intervention, glucose and insulin levels were measured every 30 min for 2 h after a 75-g dextrose load, along with glycated hemoglobin A1c (A1C) and lipid profile. Twelve patients received A. dracunculus (1000 mg) before breakfast and dinner for 90 days; the remaining 12 patients received placebo. Area under the curve (AUC) of glucose and insulin, total insulin secretion, first phase of insulin secretion, and insulin sensitivity were calculated. Wilcoxon signed-rank, Mann-Whitney U, and chi-square tests were used for statistical analyses. The institutional ethics committee approved the protocol. After A. dracunculus administration, there were significant decreases in systolic blood pressure (SBP; 120.0 ± 11.3 vs. 113.0 ± 11.2 mmHg, P AUC of insulin (56,136.0 ± 27,426.0 vs. 44,472.0 ± 23,370.0 pmol/L, P AUC of insulin, and total insulin secretion with a significant increase in HDL-C levels.

  18. Effect Of Aqueous And Hydroalcoholic Extract Of Beberis Vulgaris On Insulin Secretion From Islets Of Langerhans Isolated From Male Mice

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    A Ahangarpour

    2012-10-01

    Full Text Available Background & Aim: considering the use of Beberis vulgaris in traditional medicine as a blood sugar depressant, in this study, the effect of Beberis vulgaris extracts were investigated on the level of insulin secretion from islets isolated of langerhans in male mice. Methods: This experimental study was carried out on 90 adult male mice, NMARI strains weighing 20-25 g. Pancreatic islets from normal mice were isolated by collagenase digestion method. Then the aqueous and hydro-alcoholic extract of Beberis vulgaris at 0.05, 0.1, and 1 mg/ml concentrations and glyburide at 1 and 10 μM concentrations were applied on islets isolated in three different concentration of glucose solution (2.8, 5.6 and 16.7 mM. Insulin secretion from hand-picked islets were evaluated in the static incubation system. The level of Insulin secretion was measured by the ELISA insulin kit. Data were analyzed with variance analysis. Results: Insulin secretion was significantly increased at 16.7 mM glucose concentration in comparison with 2.8 and 5.6 mM glucose concentration (p<0.05. Incubation of pancreatic islets isolated at 2.8 and 5.6 mM glucose concentration and low concentrations of extract (0.05 and 0.1mg/ml significantly increased the insulin secretion (p<0.05. Glyburide at 10 μM concentration was more effective than aqueous and hydro alcoholic extract of Beberis vulgaris at 16.7 mM glucose. Conclusion: The present study supported the anti-diabetic effect of Beberis vulgaris extracts in vitro with low glucose concentration and it suggests that one of the anti diabetic mechanisms of this plant is via pancreatic islets.

  19. Trajectories of glycaemia, insulin sensitivity, and insulin secretion before diagnosis of type 2 diabetes: an analysis from the Whitehall II study

    DEFF Research Database (Denmark)

    Tabák, A.G.; Jokela, M.; Akbaraly, T.N.

    2009-01-01

    BACKGROUND: Little is known about the timing of changes in glucose metabolism before occurrence of type 2 diabetes. We aimed to characterise trajectories of fasting and postload glucose, insulin sensitivity, and insulin secretion in individuals who develop type 2 diabetes. METHODS: We analysed data...... from our prospective occupational cohort study (Whitehall II study) of 6538 (71% male and 91% white) British civil servants without diabetes mellitus at baseline. During a median follow-up period of 9.7 years, 505 diabetes cases were diagnosed (49.1% on the basis of oral glucose tolerance test). We...... assessed retrospective trajectories of fasting and 2-h postload glucose, homoeostasis model assessment (HOMA) insulin sensitivity, and HOMA beta-cell function from up to 13 years before diabetes diagnosis (diabetic group) or at the end of follow-up (non-diabetics). FINDINGS: Multilevel models adjusted...

  20. 1,5-anhydroglucitol is associated with early-phase insulin secretion in chinese patients with newly diagnosed type 2 diabetes mellitus.

    Science.gov (United States)

    Ma, Xiaojing; Hao, Yaping; Hu, Xiang; Luo, Yuqi; Deng, Zixuan; Zhou, Jian; Bao, Yuqian; Jia, Weiping

    2015-05-01

    The goal of the present study was to explore the correlations of 1,5-anhydroglucitol (l,5-AG), glycated hemoglobin (HbA1c), and glycated albumin (GA) with insulin sensitivity and secretion. In total, 302 patients with newly diagnosed type 2 diabetes mellitus (166 men, 136 women) were enrolled in this study. The homeostasis model assessment for insulin resistance (HOMA-IR) and homeostasis model assessment for β-cell function (HOMA-β) were calculated to determine the basal insulin sensitivity and secretion. The insulinogenic index (IGI) was used to evaluate early-phase insulin secretion. 1,5-AG and GA were assayed via the enzymatic method, and HbA1c was detected by high-pressure liquid chromatography. Among all 302 subjects, the serum 1,5-AG level was 13.1±7.2 μg/mL, and the HbA1c and GA levels [median (interquartile range)] were 6.7% (6.2-7.3%) and 17.7% (16.0-19.5%), respectively. Increased 1,5-AG quartiles were accompanied by trends toward a decreased HOMA-IR and an increased HOMA-β and IGI (for all trends, P1). 1,5-AG was negatively associated with HOMA-IR (r=-0.200, P1) and positively associated with HOMA-β and IGI (r=0.210 and 0.413, respectively; both P1). 1,5-AG was independently related to HOMA-IR and HOMA-β and exhibited an independent positive association with IGI (standardized β=0.242, P1). Additionally, both HbA1c and GA were independently correlated with HOMA-IR and HOMA-β. 1,5-AG is not only correlated with basal insulin sensitivity and secretion, but also closely associated with early-phase insulin secretion in Chinese patients with newly diagnosed type 2 diabetes mellitus.

  1. Common variants related to serum uric acid concentrations are associated with glucose metabolism and insulin secretion in a Chinese population.

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    Xue Sun

    Full Text Available Elevated serum uric acid concentration is an independent risk factor and predictor of type 2 diabetes (T2D. Whether the uric acid-associated genes have an impact on T2D remains unclear. We aimed to investigate the effects of the uric acid-associated genes on the risk of T2D as well as glucose metabolism and insulin secretion.We recruited 2,199 normal glucose tolerance subjects from the Shanghai Diabetes Study I and II and 2,999 T2D patients from the inpatient database of Shanghai Diabetes Institute. Fifteen single nucleotide polymorphisms (SNPs mapped in or near 11 loci (PDZK1, GCKR, LRP2, SLC2A9, ABCG2, LRRC16A, SLC17A1, SLC17A3, SLC22A11, SLC22A12 and SF1 were genotyped and serum biochemical parameters related to uric acid and T2D were determined.SF1 rs606458 showed strong association to T2D in both males and females (p = 0.034 and 0.0008. In the males, LRRC16A was associated with 2-h insulin and insulin secretion (p = 0.009 and 0.009. SLC22A11 was correlated with HOMA-B and insulin secretion (p = 0.048 and 0.029. SLC2A9 rs3775948 was associated with 2-h glucose (p = 0.043. In the females, LRP2 rs2544390 and rs1333049 showed correlations with fasting insulin, HOMA-IR and insulin secretion (p = 0.028, 0.033 and 0.052 and p = 0.034, 0.047 and 0.038, respectively. SLC2A9 rs11722228 was correlated with 2-h glucose, 2-h insulin and insulin secretion (p = 0.024, 0.049 and 0.049, respectively.Our results indicated that the uric acid-associated genes have an impact on the risk of T2D, glucose metabolism and insulin secretion in a Chinese population.

  2. Zinc Status Affects Glucose Homeostasis and Insulin Secretion in Patients with Thalassemia

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    Ellen B. Fung

    2015-06-01

    Full Text Available Up to 20% of adult patients with Thalassemia major (Thal live with diabetes, while 30% may be zinc deficient. The objective of this study was to explore the relationship between zinc status, impaired glucose tolerance and insulin sensitivity in Thal patients. Charts from thirty subjects (16 male, 27.8 ± 9.1 years with Thal were reviewed. Patients with low serum zinc had significantly lower fasting insulin, insulinogenic and oral disposition indexes (all p < 0.05 and elevated glucose response curve, following a standard 75 g oral load of glucose compared to those with normal serum zinc after controlling for baseline (group × time interaction p = 0.048. Longitudinal data in five patients with a decline in serum zinc over a two year follow up period (−19.0 ± 9.6 μg/dL, showed consistent increases in fasting glucose (3.6 ± 3.2 mg/dL and insulin to glucose ratios at 120 min post glucose dose (p = 0.05. Taken together, these data suggest that the frequently present zinc deficiency in Thal patients is associated with decreased insulin secretion and reduced glucose disposal. Future zinc trials will require modeling of oral glucose tolerance test data and not simply measurement of static indices in order to understand the complexities of pancreatic function in the Thal patient.

  3. Effects of experimentally induced mild hyperthyroidism on growth hormone and insulin secretion and sex steroid levels in healthy young men.

    Science.gov (United States)

    Lovejoy, J C; Smith, S R; Bray, G A; Veldhuis, J D; Rood, J C; Tulley, R

    1997-12-01

    Although triiodothyronine (T3) exerts major regulatory actions in both animals and humans, most clinical studies of T3 administration have been relatively short-term. The present study examined the effects of more than 2 months (63 days) of low-dose T3 treatment on overnight pulsatile growth hormone (GH) secretion, short-term insulin secretion, and of sex steroid levels in seven healthy, lean men studied at an inpatient metabolic unit. At baseline, there were strong correlations between sex hormone-binding globulin (SHBG) and several measures of GH production, including total GH production (r = .99), GH interburst interval (r = -.75), and GH mass (r = .82). SHBG was also inversely correlated with basal insulin secretion (r = -.74). There was a 42% increase in serum levels of total testosterone (18.5 +/- 1.3 to 26.3 +/- 1.8 nmol/L, P = .005) and a 150% increase in SHBG (18.0 +/- 2.2 to 44.9 +/- 7.0 nmol/L, P = .008) following T3 treatment. Estradiol and free testosterone levels were unchanged by treatment, although free testosterone decreased from 142.8 +/- 18.4 to 137.3 +/- 19.5 pmol/L. T3 treatment significantly reduced the GH interburst interval (P secretion. There were no statistically significant effects of T3 treatment on insulin secretion, although insulin peak amplitude, mass secreted per burst, and total production all decreased. We conclude that experimentally induced T3 excess in healthy men produces significant and sustained changes in sex hormone levels and GH secretion. Furthermore, there are strong associations between SHBG and both GH and insulin secretion independent of thyroid hormone excess that require additional study.

  4. Biotin enhances ATP synthesis in pancreatic islets of the rat, resulting in reinforcement of glucose-induced insulin secretion.

    Science.gov (United States)

    Sone, Hideyuki; Sasaki, Yuka; Komai, Michio; Toyomizu, Masaaki; Kagawa, Yasuo; Furukawa, Yuji

    2004-02-13

    Previous studies showed that biotin enhanced glucose-induced insulin secretion. Changes in the cytosolic ATP/ADP ratio in the pancreatic islets participate in the regulation of insulin secretion by glucose. In the present study we investigated whether biotin regulates the cytosolic ATP/ADP ratio in glucose-stimulated islets. When islets were stimulated with glucose plus biotin, the ATP/ADP ratio increased to approximately 160% of the ATP/ADP ratio in islets stimulated with glucose alone. The rate of glucose oxidation, assessed by CO(2) production, was also about 2-fold higher in islets treated with biotin. These increasing effects of biotin were proportional to the effects seen in insulin secretion. There are no previous reports of vitamins, such as biotin, directly affecting ATP synthesis. Our data indicate that biotin enhances ATP synthesis in islets following the increased rate of substrate oxidation in mitochondria and that, as a consequence of these events, glucose-induced insulin release is reinforced by biotin.

  5. Exenatide augments first- and second-phase insulin secretion in response to intravenous glucose in subjects with type 2 diabetes

    DEFF Research Database (Denmark)

    Fehse, Frauke; Trautmann, Michael; Holst, Jens Juul

    2005-01-01

    CONTEXT: First-phase insulin secretion (within 10 min after a sudden rise in plasma glucose) is reduced in type 2 diabetes mellitus (DM2). The incretin mimetic exenatide has glucoregulatory activities in DM2, including glucose-dependent enhancement of insulin secretion. OBJECTIVE: The objective...... of the study was to determine whether exenatide can restore a more normal pattern of insulin secretion in subjects with DM2. DESIGN: Fasted subjects received iv insulin infusion to reach plasma glucose 4.4-5.6 mmol/liter. Subjects received iv exenatide (DM2) or saline (DM2 and healthy volunteers), followed...... by iv glucose challenge. PATIENTS: Thirteen evaluable DM2 subjects were included in the study: 11 males, two females; age, 56 +/- 7 yr; body mass index, 31.7 +/- 2.4 kg/m2; hemoglobin A1c, 6.6 +/- 0.7% (mean +/- sd) treated with diet/exercise (n = 1), metformin (n = 10), or acarbose (n = 2). Controls...

  6. Insulin secretion and glucose uptake by isolated islets of the hamster. Effect of insulin, proinsulin and C-peptide

    Energy Technology Data Exchange (ETDEWEB)

    Dunbar, J C; McLaughlin, W J; Walsh, M F.J.; Foa, P P [Sinai Hospital of Detroit, Mich. (USA). Dept. of Research

    1976-01-01

    Isolated pancreatic islets of normal hamsters were perfused either in a closed or in a open system. When the buffer was recirculated and the endogenous insulin was allowed to accumulate, the islets secreted significantly less insulin than when the system was open and the endogenous insulin was washed away. The addition of monocomponent insulin or of proinsulin to the perfusion buffer significantly decreased insulin secretion. The inhibitory action of proinsulin was significantly greater than that of monocomponent insulin. C peptide had no effect. When pancreatic islets were incubated in a fixed volume of stationary buffer containing unlabeled glucose (1.0 mg or 3.0 mg/ml) and glucose-U-/sup 14/C (1.0 ..mu..C/ml), the amount of insulin secreted and the /sup 14/CO/sub 2/ produced by each islet decreased progressively as the number of islets in the sample increased. Under these conditions, the concentration of insulin required to inhibit insulin secretion increased with the concentration of glucose in the medium. Proinsulin did not alter the incorporation of leucine-4.5-/sup 3/H into total extractable insulin (insulin + proinsulin). Thus, insulin and proinsulin appear to inhibit insulin release, but not insulin synthesis.

  7. Hyperinsulinemia in the physiologic range is not superior to short-term fasting in suppressing insulin secretion in obese men.

    Science.gov (United States)

    Pincelli, A I; Brunani, A; Caumo, A; Scacchi, M; Pasqualinotto, L; Tibaldi, A; Dubini, A; Bonadonna, S; Cavagnini, F

    2001-01-01

    The negative-feedback control exerted by plasma insulin on beta-cell insulin release in normal-weight and obese subjects is still a matter of debate. Subjects submitted to a euglycemic insulin clamp undergo a suppression of insulin secretion that is due to both the infused insulin and the 2- to 3-hour fast during the procedure. We elected to elucidate the role of physiologic hyperinsulinemia per se in the insulin negative autofeedback in obese men. Ten men with massive uncomplicated obesity (age, 18 to 37 years; body mass index [BMI], 41 +/- 1.15 kg/m2) and 6 normal-weight healthy men (age, 22 to 30 years; BMI, 22 +/- 0.28 kg/m2) underwent 2 studies in random order: (1) a euglycemic-hyperinsulinemic glucose clamp with an insulin infusion rate of 1 mU/kg/min and (2) a control study with saline infusion. Serum C-peptide concentrations were significantly higher in obese versus control subjects at baseline (2.54 +/- 0.178 v 1.63 +/- 0.256 ng/mL, P < .05). Exogenous insulin infusion significantly suppressed serum C-peptide at steady state ([SS] last 30 minutes of insulin or saline infusion) in controls (mean of the last 4 measurements from 120 minutes to 150 minutes, 0.86 +/- 0.306 ng/mL, P < .05 vbaseline) but not in obese patients (2.03 +/- 0.26 ng/mL, nonsignificant [NS] v baseline). During the saline infusion studies, C-peptide levels slightly and similarly declined over time in both groups (2.71 +/- 0.350 at baseline v 2.31 +/- 0.300 ng/mL at SS in obese patients, NS, and 1.96 +/- 0.189 v 1.62 +/- 0.150 ng/mL in controls, NS). This study shows that in obese men hyperinsulinemia within the postprandial range is not superior to a 2.5-hour fast for the suppression of beta-cell activity, suggesting an impairment of the insulin negative autofeedback in this clinical condition.

  8. The Relationship between 25-hydroxyvitamin D Levels, Insulin Sensitivity and Insulin Secretion in Women 3 Years after Delivery.

    Science.gov (United States)

    Tänczer, Tímea; Magenheim, Rita; Fürst, Ágnes; Domján, Beatrix; Janicsek, Zsófia; Szabó, Eszter; Ferencz, Viktória; Tabák, Ádám G

    2017-12-01

    There is a direct correlation between 25-hydroxyvitamin D (25[OH]D) levels and insulin sensitivity. Furthermore, women with gestational diabetes (GDM) may have lower levels of 25(OH)D compared to controls. The present study intended to investigate 25(OH)D levels and their association with insulin sensitivity and insulin secretion in women with prior GDM and in controls 3.2 years after delivery. A total of 87 patients with prior GDM and 45 randomly selected controls (age range, 22 to 44 years) with normal glucose tolerance during pregnancy nested within a cohort of all deliveries at Saint Margit Hospital, Budapest, between January 1 2005, and December 31 2006, were examined. Their 25(OH) D levels were measured by radioimmunoassay. Insulin sensitivity and fasting insulin secretion were estimated using the homeostasis model asssessment (HOMA) calculator and early insulin secretion by the insulinogenic index based on a 75 g oral glucose tolerance test. There was no significant difference in 25(OH)D levels between cases and controls (27.2±13.1 [±SD] vs. 26.9±9.8 ng/L). There was a positive association between HOMA insulin sensitivity and 25(OH)D levels (beta = 0.017; 95% CI 0.001 to 0.034/1 ng/mL) that was robust to adjustment for age and body mass index. There was a nonsignificant association between HOMA insulin secretion and 25(OH)D (p=0.099), while no association was found with the insulinogenic index. Prior GDM status was not associated with 25(OH)D levels; however, 25(OH) D levels were associated with HOMA insulin sensitivity. It is hypothesized that the association between HOMA insulin secretion and 25(OH)D levels is related to the autoregulation of fasting glucose levels because no association between 25(OH)D and insulinogenic index was found. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

  9. Relaxation response induces temporal transcriptome changes in energy metabolism, insulin secretion and inflammatory pathways.

    Directory of Open Access Journals (Sweden)

    Manoj K Bhasin

    Full Text Available The relaxation response (RR is the counterpart of the stress response. Millennia-old practices evoking the RR include meditation, yoga and repetitive prayer. Although RR elicitation is an effective therapeutic intervention that counteracts the adverse clinical effects of stress in disorders including hypertension, anxiety, insomnia and aging, the underlying molecular mechanisms that explain these clinical benefits remain undetermined. To assess rapid time-dependent (temporal genomic changes during one session of RR practice among healthy practitioners with years of RR practice and also in novices before and after 8 weeks of RR training, we measured the transcriptome in peripheral blood prior to, immediately after, and 15 minutes after listening to an RR-eliciting or a health education CD. Both short-term and long-term practitioners evoked significant temporal gene expression changes with greater significance in the latter as compared to novices. RR practice enhanced expression of genes associated with energy metabolism, mitochondrial function, insulin secretion and telomere maintenance, and reduced expression of genes linked to inflammatory response and stress-related pathways. Interactive network analyses of RR-affected pathways identified mitochondrial ATP synthase and insulin (INS as top upregulated critical molecules (focus hubs and NF-κB pathway genes as top downregulated focus hubs. Our results for the first time indicate that RR elicitation, particularly after long-term practice, may evoke its downstream health benefits by improving mitochondrial energy production and utilization and thus promoting mitochondrial resiliency through upregulation of ATPase and insulin function. Mitochondrial resiliency might also be promoted by RR-induced downregulation of NF-κB-associated upstream and downstream targets that mitigates stress.

  10. Insulin secretion enhancing activity of roselle calyx extract in normal and streptozotocin-induced diabetic rats

    Science.gov (United States)

    Wisetmuen, Eamruthai; Pannangpetch, Patchareewan; Kongyingyoes, Bunkerd; Kukongviriyapan, Upa; Yutanawiboonchai, Wiboonchai; Itharat, Arunporn

    2013-01-01

    Background and Objective: Our recent study revealed the antihyperglycemic activity of an ethanolic extract of roselle calyxes (Hibiscus sabdariffa) in diabetic rats. The present study had, therefore, an objective to investigate the mechanism underlying this activity. Materials and Methods: Male Sprague Dawley rats were induced to be diabetes by intraperitoneal injection of 45 mg/kg streptozotocin (STZ). Normal rats as well as diabetic rats were administered with the ethanolic extract of H. sabdariffa calyxes (HS-EE) at 0.1 and 1.0 g/kg/day, respectively, for 6 weeks. Then, blood glucose and insulin levels, at basal and glucose-stimulated secretions, were measured. The pancreas was dissected to examine histologically. Results: HS-EE 1.0 g/kg/day significantly decreased the blood glucose level by 38 ± 12% in diabetic rats but not in normal rats. In normal rats, treatment with 1.0 g/kg HS-EE increased the basal insulin level significantly as compared with control normal rats (1.28 ± 0.25 and 0.55 ± 0.05 ng/ml, respectively). Interestingly, diabetic rats treated with 1.0 g/kg HS-EE also showed a significant increase in basal insulin level as compared with the control diabetic rats (0.30 ± 0.05 and 0.15 ± 0.01 ng/ml, respectively). Concerning microscopic histological examination, HS-EE 1.0 g/kg significantly increased the number of islets of Langerhans in both normal rats (1.2 ± 0.1 and 2.0 ± 0.1 islet number/10 low-power fields (LPF) for control and HS-EE treated group, respectively) and diabetic rats (1.0 ± 0.3 and 3.9 ± 0.6 islet number/10 LPF for control and HS-EE treated group, respectively). Conclusion: The antidiabetic activity of HS-EE may be partially mediated via the stimulating effect on insulin secretion. PMID:23798879

  11. Environmental factors and dam characteristics associated with insulin sensitivity and insulin secretion in newborn Holstein calves

    International Nuclear Information System (INIS)

    Kamal, M.M.; Van Eetvelde, M.; Bogaert, H.; Hostens, M.; Vandaele, L.; Shamsuddin, M.; Opsomer, G.

    2016-01-01

    Full text: The objective of the present retrospective cohort study was to evaluate potential associations between environmental factors and dam characteristics, including level of milk production during gestation, and insulin traits in newborn Holstein calves. Birth weight and gestational age of the calves at delivery were determined. On the next day, heart girth, wither height and diagonal length of both the calves and their dams were measured. Parity, body condition score and age at calving were recorded for all dams. For the cows, days open before last gestation, lactation length (LL), lenght of dry period (DP) and calving interval were also calculated. The magnitude and shape of the lactation curve both quantified using the MilkBot model based on monthly milk weights, were used to calculate the amount of milk produced during gestation. Using the same procedure, cumulative milk production from conception to drying off (MGEST) was calculated. A blood sample was collected from all calves (n=481; 169 born to heifers and 312 born to cows) at least 5 h after a milk meal on day 3 of life to measure basal glucose and insulin levels. In addition, an intravenous glucose-stimulated insulin secretion test was performed in a subset of the calves (n=316). After descriptive analysis, generalized linear mixed models were used to identify factors that were significantly associated with the major insulin traits (Insb, basal insulin level; QUICKI, quantitative insulin sensitivity check index; AIR, acute insulin response; DI, disposition index) of the newborn calves. The overall average birth weight of the calves was 42.7 ± 5.92 kg. The insulin traits were significantly associated with MGEST (P=0.076) and longer DP (P=0.034). The QUICKI was estimated to be lower in calves born to the cows having passed a higher MGEST (P=0.030) and longer DP (P=0.058). Moreover, the AIR (P=0.009) and DI (P=0.049) were estimated to be lower in male compared with female calves. Furthermore, the AIR

  12. 1-Hour OGTT Plasma Glucose as a Marker of Progressive Deterioration of Insulin Secretion and Action in Pregnant Women

    Directory of Open Access Journals (Sweden)

    Alessandra Ghio

    2012-01-01

    Full Text Available Considering old GDM diagnostic criteria, alterations in insulin secretion and action are present in women with GDM as well as in women with one abnormal value (OAV during OGTT. Our aim is to assess if changes in insulin action and secretion during pregnancy are related to 1-hour plasma glucose concentration during OGTT. We evaluated 3 h/100 g OGTT in 4,053 pregnant women, dividing our population on the basis of 20 mg/dL increment of plasma glucose concentration at 1 h OGTT generating 5 groups (<120 mg/dL, =661; 120–139 mg/dL, =710; 140–159 mg/dL, =912; 160–179 mg/dL, =885; and ≥180 mg/dL, =996. We calculated incremental area under glucose (AUCgluc and insulin curves (AUCins, indexes of insulin secretion (HOMA-B, and insulin sensitivity (HOMA-R, AUCins/AUCgluc. AUCgluc and AUCins progressively increased according to 1-hour plasma glucose concentrations (both <0.0001 for trend. HOMA-B progressively declined (<0.001, and HOMA-R progressively increased across the five groups. AUCins/AUCgluc decreased in a linear manner across the 5 groups (<0.001. Analysing the groups with 1-hour value <180 mg/dL, defects in insulin secretion (HOMA-B: −29.7% and sensitivity (HOMA-R: +15% indexes were still apparent (all <0.001. Progressive increase in 1-hour OGTT is associated with deterioration of glucose tolerance and alterations in indexes of insulin action and secretion.

  13. Acute but not chronic activation of brain glucagon-like peptide-1 receptors enhances glucose-stimulated insulin secretion in mice.

    Science.gov (United States)

    Tudurí, E; Beiroa, D; Porteiro, B; López, M; Diéguez, C; Nogueiras, R

    2015-08-01

    To investigate the role of brain glucagon-like peptide-1 (GLP-1) in pancreatic β-cell function. To determine the role of brain GLP-1 receptor (GLP-1R) on β-cell function, we administered intracerebroventricular (i.c.v.) infusions of GLP-1 or the specific GLP-1 antagonist exendin-9 (Ex-9), in both an acute and a chronic setting. We observed that acute i.c.v. GLP-1 infusion potentiates glucose-stimulated insulin secretion (GSIS) and improves glucose tolerance, whereas central GLP-1R blockade with Ex-9 impaired glucose excursion after a glucose load. Sustained activation of central nervous system GLP-1R, however, did not produce any effect on either GSIS or glucose tolerance. Similarly, ex vivo GSIS performed in islets from mice chronically infused with i.c.v. GLP-1 resulted in no differences compared with controls. In addition, in mice fed a high-fat diet we observed that acute i.c.v. GLP-1 infusion improved glucose tolerance without changes in GSIS, while chronic GLP-1R activation had no effect on glucose homeostasis. Our results indicate that, under non-clamped conditions, brain GLP-1 plays a functional neuroendocrine role in the acute regulation of glucose homeostasis in both lean and obese rodents. © 2015 John Wiley & Sons Ltd.

  14. Opiate-prostaglandin interactions in the regulation of insulin secretion from rat islets of Langerhans in vitro

    International Nuclear Information System (INIS)

    Green, I.C.; Tadayyon, M.

    1988-01-01

    The inadequate insulin secretory response to glucose stimulation in non-insulin dependent diabetes has been attributed to many factors including high PGE 2 levels blunting the secretory response, and to the existence of inhibitory opiate activity in vivo. The purpose of the present work was to see if there was a connection between these two independent theories. Radioimmunoassayable PGE 2 in islets of Langerhans was found to be proportional to islet number and protein content and was typically 4 to 5pg/μg islet protein. Indomethacin sodium salicylate and chlorpropamide all lowered islet PGE 2 levels and stimulated insulin release in vitro. Dynorphin stimulated insulin release at a concentration of 6 x 10 -9 M, while lowering islet PGE 2 . Conversely, at a higher concentration, dynorphin had no stimulatory effect on insulin secretion and did not lower PGE 2 levels in islets or in the incubation media. The stimulatory effects of dynorphin and sodium salicylate on insulin secretion were blocked by exogenous PGE 2 . PGE 2 at a lower concentration did not exert any inhibitory effect on dynorphin- or sodium salicylate-induced insulin release. This concentration of exogenous PGE 2 stimulated insulin release in the presence of 6mM glucose

  15. Radioimmunoassay of seric C-peptide. Practical value in the study of insulin secretion. Results of 140 stimulation tests

    International Nuclear Information System (INIS)

    Wafflart, Jean.

    1977-10-01

    C-peptide, which appears as a by-product of insulin synthesis, is secreted with this latter in equimolar quantities but is not degraded in the liver. It thus reflects indirectly the insulin secreted. After the structure of C-peptide was determined in 1971 by OYER it was synthesized by YANAIHARA and a radioimmunoassay was developed by KANEKO in 1974. This work was made possible by the recent commercialisation of a Japanese analysis kit, the 'DAIICHI' kit, and its availability through GUERBET TESTS. Part one describes the structural, physiological and immuno properties of C-peptide and its method of determination. Part two is devoted to a review of foreign publications on the practical interest of the C-peptide measurement. Part three gives the results of 140 oral or venous stimulation tests where blood sugar, blood insulin and C-peptide are measured in parallel. The different diabetic pathologies are explored and compared against normal subjects. The purpose of this work is to establish the value of C-peptide as a reflection of insulin secretion on the one hand, and that of a parallel insulin and C-peptide determination on the other [fr

  16. Glucose-stimulated prehepatic insulin secretion is associated with circulating alanine, triglyceride, glucagons, lactate and TNF-alfa in patients with HIV-lipodystrophy

    DEFF Research Database (Denmark)

    Haugaard, Steen B; Andersen, Ove; Pedersen, SB

    2006-01-01

    with the remaining HIV-infected patients (all Ptriglyceride, alanine, glucagon, lactate and TNF-alpha may be associated with alterations in the first-phase prehepatic insulin secretion response to intravenous glucose in normoglycaemic lipodystrophic HIV-infected patients.......OBJECTIVES: We examined whether insulin-resistant lipodystrophic HIV-infected patients with known high fasting prehepatic insulin secretion rates (FISRs) displayed alterations in first-phase prehepatic insulin response to intravenous glucose (ISREG0-10 min). METHODS: Eighteen normoglycaemic...... lipodystrophic HIV-infected (LIPO) patients and 25 normoglycaemic nonlipodystrophic HIV-infected patients (controls) were included in the study. The prehepatic insulin secretion rate was estimated by deconvolution of C-peptide concentrations, and insulin sensitivity (SIRd) was estimated by the glucose clamp...

  17. Glucose-stimulated prehepatic insulin secretion is associated with circulating alanine, triglyceride, glucagon, lactate and TNF-alpha in patients with HIV-lipodystrophy

    DEFF Research Database (Denmark)

    Haugaard, S B; Andersen, O; Pedersen, S B

    2006-01-01

    with the remaining HIV-infected patients (all Ptriglyceride, alanine, glucagon, lactate and TNF-alpha may be associated with alterations in the first-phase prehepatic insulin secretion response to intravenous glucose in normoglycaemic lipodystrophic HIV-infected patients.......OBJECTIVES: We examined whether insulin-resistant lipodystrophic HIV-infected patients with known high fasting prehepatic insulin secretion rates (FISRs) displayed alterations in first-phase prehepatic insulin response to intravenous glucose (ISREG0-10 min). METHODS: Eighteen normoglycaemic...... lipodystrophic HIV-infected (LIPO) patients and 25 normoglycaemic nonlipodystrophic HIV-infected patients (controls) were included in the study. The prehepatic insulin secretion rate was estimated by deconvolution of C-peptide concentrations, and insulin sensitivity (SIRd) was estimated by the glucose clamp...

  18. A Ratiometric Sensor for Imaging Insulin Secretion in Single beta Cells

    Czech Academy of Sciences Publication Activity Database

    Schifferer, M.; Yushchenko, Dmytro A.; Stein, F.; Bolbat, A.; Schultz, C.

    2017-01-01

    Roč. 24, č. 4 (2017), s. 525-531 ISSN 2451-9448 Institutional support: RVO:61388963 Keywords : zinc transporter ZnT8 * line MIN6 * glucose homeostasis Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology http://www.sciencedirect.com/science/article/pii/S2451945617300624

  19. Mathematical Beta Cell Model for Insulin Secretion following IVGTT and OGTT

    DEFF Research Database (Denmark)

    Madsen, Henrik; Henriksen, Jan Erik; Karlsson, Mats

    2006-01-01

    estimates. For the IVGTT, A correlates well ( r=0.96) with the 10 min area under the curve of insulin above baseline, whereas k represents a new and possibly more fundamental first phase index. For the useful second phase index , a correlation of 0.75 was found between IVGTT and OGTT estimates....

  20. Metformin Ameliorates Dysfunctional Traits of Glibenclamide- and Glucose-Induced Insulin Secretion by Suppression of Imposed Overactivity of the Islet Nitric Oxide Synthase-NO System.

    Directory of Open Access Journals (Sweden)

    Ingmar Lundquist

    Full Text Available Metformin lowers diabetic blood glucose primarily by reducing hepatic gluconeogenesis and increasing peripheral glucose uptake. However, possible effects by metformin on beta-cell function are incompletely understood. We speculated that metformin might positively influence insulin secretion through impacting the beta-cell nitric oxide synthase (NOS-NO system, a negative modulator of glucose-stimulated insulin release. In short-time incubations with isolated murine islets either glibenclamide or high glucose augmented insulin release associated with increased NO production from both neural and inducible NOS. Metformin addition suppressed the augmented NO generation coinciding with amplified insulin release. Islet culturing with glibenclamide or high glucose revealed pronounced fluorescence of inducible NOS in the beta-cells being abolished by metformin co-culturing. These findings were reflected in medium nitrite-nitrate levels. A glucose challenge following islet culturing with glibenclamide or high glucose revealed markedly impaired insulin response. Metformin co-culturing restored this response. Culturing murine islets and human islets from controls and type 2 diabetics with high glucose or high glucose + glibenclamide induced a pronounced decrease of cell viability being remarkably restored by metformin co-culturing. We show here, that imposed overactivity of the beta-cell NOS-NO system by glibenclamide or high glucose leads to insulin secretory dysfunction and reduced cell viability and also, importantly, that these effects are relieved by metformin inhibiting beta-cell NO overproduction from both neural and inducible NOS thus ameliorating a concealed negative influence by NO induced by sulfonylurea treatment and/or high glucose levels. This double-edged effect of glibenclamide on the beta-cellsuggests sulfonylurea monotherapy in type 2 diabetes being avoided.

  1. Trajectories of glycaemia, insulin sensitivity and insulin secretion in South Asian and white individuals before diagnosis of type 2 diabetes

    DEFF Research Database (Denmark)

    Hulman, Adam; Simmons, Rebecca K; Brunner, Eric J

    2017-01-01

    AIMS/HYPOTHESIS: South Asian individuals have reduced insulin sensitivity and increased risk of type 2 diabetes compared with white individuals. Temporal changes in glycaemic traits during middle age suggest that impaired insulin secretion is a particular feature of diabetes development among South...... Asians. We therefore aimed to examine ethnic differences in early changes in glucose metabolism prior to incident type 2 diabetes. METHODS: In a prospective British occupational cohort, subject to 5 yearly clinical examinations, we examined ethnic differences in trajectories of fasting plasma glucose...... (FPG), 2 h post-load plasma glucose (2hPG), fasting serum insulin (FSI), 2 h post-load serum insulin (2hSI), HOMA of insulin sensitivity (HOMA2-S) and secretion (HOMA2-B), and the Gutt insulin sensitivity index (ISI0,120) among 120 South Asian and 867 white participants who developed diabetes during...

  2. Roles of circulating WNT-signaling proteins and WNT-inhibitors in human adiposity, insulin resistance, insulin secretion, and inflammation.

    Science.gov (United States)

    Almario, R U; Karakas, S E

    2015-02-01

    Wingless-type MMTV integration site family member (WNT) signaling and WNT-inhibitors have been implicated in regulation of adipogenesis, insulin resistance, pancreatic function, and inflammation. Our goal was to determine serum proteins involved in WNT signaling (WNT5 and WISP2) and WNT inhibition (SFRP4 and SFRP5) as they relate to obesity, serum adipokines, insulin resistance, insulin secretion, and inflammation in humans. Study population comprised 57 insulin resistant women with polycystic ovary syndrome (PCOS) and 27 reference women. In a cross-sectional study, blood samples were obtained at fasting, during oral, and frequently sampled intravenous glucose tolerance tests. Serum WNT5, WISP2, and SFRP4 concentrations did not differ between PCOS vs. reference women. Serum WNT5 correlated inversely with weight both in PCOS and reference women, and correlated directly with insulin response during oral glucose tolerance test in PCOS women. Serum WISP2 correlated directly with fatty acid binding protein 4. Serum SFRP5 did not differ between obese (n=32) vs. nonobese (n=25) PCOS women, but reference women had lower SFRP5 (pPCOS groups). Serum SFRP5 correlated inversely with IL-1β, TNF-α, cholesterol, and apoprotein B. These findings demonstrated that WNT5 correlated inversely with adiposity and directly with insulin response, and the WNT-inhibitor SFRP5 may be anti-inflammatory. Better understanding of the role of WNT signaling in obesity, insulin resistance, insulin secretion, lipoprotein metabolism, and inflammation is important for prevention and treatment of metabolic syndrome, diabetes and cardiovascular disease. © Georg Thieme Verlag KG Stuttgart · New York.

  3. Glucose triggers protein kinase A-dependent insulin secretion in mouse pancreatic islets through activation of the K+ATP channel-dependent pathway

    DEFF Research Database (Denmark)

    Thams, Peter; Anwar, Mohammad R; Capito, Kirsten

    2005-01-01

    pancreatic islets was determined by radioimmunoassay. RESULTS: In islets cultured at 5.5 mmol/l glucose, and then perifused in physiological Krebs-Ringer medium, the PKA inhibitors, H89 (10 micromol/l) and PKI 6-22 amide (30 micromol/l) did not inhibit glucose (16.7 mmol/l)-induced insulin secretion...

  4. Natural history of insulin sensitivity and insulin secretion in the progression from normal glucose tolerance to impaired fasting glycemia and impaired glucose tolerance: the Inter99 study

    DEFF Research Database (Denmark)

    Faerch, Kristine; Vaag, Allan; Holst, Jens J

    2008-01-01

    of insulin sensitivity (HOMA-IS), early-phase insulin release (EPIR), and insulin secretion relative to insulin action (disposition index) were estimated. RESULTS: Five years before the pre-diabetes diagnoses (i-IFG, i-IGT, and IFG/IGT), ISI, HOMA-IS, EPIR, and disposition index were lower than...

  5. Moderate alcohol consumption is associated with improved insulin sensitivity, reduced basal insulin secretion rate and lower fasting glucagon concentration in healthy women

    DEFF Research Database (Denmark)

    Bonnet, F; Disse, E; Laville, M

    2012-01-01

    Moderate alcohol consumption is associated with a reduced risk of type 2 diabetes with a stronger effect in women. As the underlying mechanisms remain poorly characterised, we investigated its relationship with insulin resistance, insulin secretion, clearance of insulin and glucagon concentration....

  6. The effect of 30 months of low-dose replacement therapy with recombinant human growth hormone (rhGH) on insulin and C-peptide kinetics, insulin secretion, insulin sensitivity, glucose effectiveness, and body composition in GH-deficient adults

    DEFF Research Database (Denmark)

    Rosenfalck, A M; Maghsoudi, S; Fisker, S

    2000-01-01

    The aim of the present study was to evaluate the long-term (30 months) metabolic effects of recombinant human GH (rhGH) given in a mean dose of 6.7 microg/kg x day (= 1.6 IU/day), in 11 patients with adult GH deficiency. Glucose metabolism was evaluated by an oral glucose tolerance test and an iv...... (frequently sampled iv glucose tolerance test) glucose tolerance test, and body composition was estimated by dual-energy x-ray absorptiometry. Treatment with rhGH induced persistent favorable changes in body composition, with a 10% increase in lean body mass (P ... in glucose tolerance, beta-cell response was still inappropriate. Our conclusion is that long-term rhGH-replacement therapy in GH deficiency adults induced a significant deterioration in glucose tolerance, profound changes in kinetics of C-peptide, and insulin and prehepatic insulin secretion, despite...

  7. Meal composition affects insulin secretion in women with type 2 diabetes: a comparison with healthy controls. The Hoorn prandial study.

    Science.gov (United States)

    Alssema, M; Schindhelm, R K; Rijkelijkhuizen, J M; Kostense, P J; Teerlink, T; Nijpels, G; Heine, R J; Dekker, J M

    2009-03-01

    Early insulin secretion following a meal is representative for normal physiology and may depend on meal composition. To compare the effects of a fat-rich and a carbohydrate-rich mixed meal on insulinogenic index as a measure of early insulin secretion in normoglycemic women (NGM) and in women with type 2 diabetes mellitus (DM2), and to assess the relationship of anthropometric and metabolic factors with insulinogenic index. Postmenopausal women, 76 with NGM and 64 with DM2, received a fat-rich meal and a carbohydrate-rich meal on separate occasions. Early insulin response was estimated as insulinogenic index ( big up tri, Deltainsulin(0-30 min)/ big up tri, Deltaglucose(0-30 min)) for each meal. Associations of fasting and postprandial triglycerides, body mass index, waist and hip circumference and alanine aminotransferase with insulinogenic indices were determined. Women with NGM present with higher insulinogenic index than women with DM2. The insulinogenic index following the fat-rich meal ( big up tri, DeltaI(30)/ big up tri, DeltaG(30) (fat)) was higher than the index following the carbohydrate-rich meal (big up tri, DeltaI(30)/ big up tri, DeltaG(30) (CH)) (Pwomen with DM2, and not significant in women with NGM). In women with DM2, homeostasis model assessment for insulin resistance was positively associated with big up tri, DeltaI(30)/ big up tri, DeltaG(30) (CH). In women with NGM, waist circumference was independently and inversely associated with big up tri, DeltaI(30)/ big up tri, DeltaG(30) (fat) and with big up tri, DeltaI(30)/ big up tri, DeltaG(30) (CH); hip circumference was positively associated with big up tri, DeltaI(30)/ big up tri, DeltaG(30) (fat). The insulinogenic index following the fat-rich meal was higher than following the isocaloric carbohydrate-rich meal, which might favorably affect postprandial glucose excursions, especially in women with DM2. The association between a larger waist circumference and a lower meal-induced insulinogenic

  8. DHEA supplementation in ovariectomized rats reduces impaired glucose-stimulated insulin secretion induced by a high-fat diet

    Directory of Open Access Journals (Sweden)

    Katherine Veras

    2014-01-01

    Full Text Available Dehydroepiandrosterone (DHEA and the dehydroepiandrosterone sulfate (DHEA-S are steroids produced mainly by the adrenal cortex. There is evidence from both human and animal models suggesting beneficial effects of these steroids for obesity, diabetes mellitus, hypertension, and osteoporosis, conditions associated with the post-menopausal period. Accordingly, we hypothesized that DHEA supplementation in ovariectomized (OVX female rats fed a high-fat diet would maintain glucose-induced insulin secretion (GSIS and pancreatic islet function. OVX resulted in a 30% enlargement of the pancreatic islets area compared to the control rats, which was accompanied by a 50% reduction in the phosphorylation of AKT protein in the pancreatic islets. However, a short-term high-fat diet induced insulin resistance, accompanied by impaired GSIS in isolated pancreatic islets. These effects were reversed by DHEA treatment, with improved insulin sensitivity to levels similar to the control group, and with increased serine phosphorylation of the AKT protein. These data confirm the protective effect of DHEA on the endocrine pancreas in a situation of diet-induced overweight and low estrogen concentrations, a phenotype similar to that of the post-menopausal period.

  9. A matlab framework for estimation of NLME models using stochastic differential equations: applications for estimation of insulin secretion rates.

    Science.gov (United States)

    Mortensen, Stig B; Klim, Søren; Dammann, Bernd; Kristensen, Niels R; Madsen, Henrik; Overgaard, Rune V

    2007-10-01

    The non-linear mixed-effects model based on stochastic differential equations (SDEs) provides an attractive residual error model, that is able to handle serially correlated residuals typically arising from structural mis-specification of the true underlying model. The use of SDEs also opens up for new tools for model development and easily allows for tracking of unknown inputs and parameters over time. An algorithm for maximum likelihood estimation of the model has earlier been proposed, and the present paper presents the first general implementation of this algorithm. The implementation is done in Matlab and also demonstrates the use of parallel computing for improved estimation times. The use of the implementation is illustrated by two examples of application which focus on the ability of the model to estimate unknown inputs facilitated by the extension to SDEs. The first application is a deconvolution-type estimation of the insulin secretion rate based on a linear two-compartment model for C-peptide measurements. In the second application the model is extended to also give an estimate of the time varying liver extraction based on both C-peptide and insulin measurements.

  10. Effect of mufa enriched extra virgin olive oil on glycemic status and insulin secretion in diabetic rats

    International Nuclear Information System (INIS)

    Naveed, A.K.; Yousaf, M.J.; Khan, S.; Ahmed, T.; Azeem, Z.

    2013-01-01

    Objective: To evaluate the effect of monounsaturated fatty acid enriched extra virgin olive oil on glycemic status and insulin secretion in diabetic rats. Study Design: Randomized Control Trial. Place and Duration of Study: Department of Biochemistry, Army Medical College, Rawalpindi in collaboration with Centre for Research in Experimental and Applied Medicine, Army Medical College, Rawalpindi and National Institute of Health, Islamabad from March 2010 to June 2011. Material and Methods: Eighty albino rats of Sprague-dawley strain weighing 200-250 g were randomly divided into two groups of 40 rats each. Rats were made diabetic by injecting streptozotocin. Group 1 and Group II were given normal rodent diet and extra virgin olive oil supplemented diet respectively for 06 weeks. At the end of experimentation, fasting blood glucose, glycosylated hemoglobin and insulin were measured. Results: There was significant decrease of fasting blood glucose and glycosylated hemoglobin and significant increase of serum insulin of group II rats when it was compared with group I (control). Conclusion: Monounsaturated fatty acids enriched extra virgin olive oil can significantly improve glycemic status and serum insulin in diabetic rats. (author)

  11. Effect of physical training on insulin secretion and action in skeletal muscle and adipose tissue of first-degree relatives of type 2 diabetic patients

    DEFF Research Database (Denmark)

    Dela, Flemming; Stallknecht, Bente Merete

    2010-01-01

    in CON but not in FDR, whereas glucose-mediated GU increased (P groups. Adipose tissue GU was not affected by training, but it was higher (abdominal, P Training increased skeletal muscle lipolysis (P ...- to sevenfold. We conclude that insulin-secretory capacity is lower in FDR than in CON and that there is dissociation between training-induced changes in insulin secretion and insulin-mediated GU. Maximal GU rates are similar between groups and increases with physical training.......Physical training affects insulin secretion and action, but there is a paucity of data on the direct effects in skeletal muscle and adipose tissue and on the effect of training in first-degree relatives (FDR) of patients with type 2 diabetes. We studied insulin action at the whole body level...

  12. Variance of the SGK1 gene is associated with insulin secretion in different European populations: results from the TUEF, EUGENE2, and METSIM studies

    DEFF Research Database (Denmark)

    Friedrich, Björn; Weyrich, Peter; Stancáková, Alena

    2008-01-01

    gene (SGK) variations and insulin secretion traits. The German TUEF project provided the screening population (N = 725), and four tagging SNPs (rs1763527, rs1743966, rs1057293, rs9402571) were investigated. EUGENE2 (N = 827) served as a replication cohort for the detected associations. Finally...... secretion only remained significant in lean TUEF participants (BMIEUGENE2 rs9402571 minor allele carriers, who had a significantly higher AUC(Ins)/AUC(Glc) (TT: 226+/-7, XG: 246+/-9; p = 0.019). Accordingly, the METSIM trial revealed a lower prevalence of type...... 2 diabetes (OR: 0.85; 95%CI: 0.71-1.01; p = 0.065, dominant model) in rs9402571 minor allele carriers. CONCLUSIONS: The rs9402571 SGK genotype associates with increased insulin secretion in lean non-diabetic TUEF/EUGENE2 participants and with lower diabetes prevalence in METSIM. Our study in three...

  13. Insulin secretion after short- and long-term low-grade free fatty acid infusion in men with increased risk of developing type 2 diabetes

    DEFF Research Database (Denmark)

    Storgaard, Heidi; Jensen, Christine B; Vaag, Allan A

    2003-01-01

    We studied the effect of a low-grade short- and long-term 20% Intralipid infusion (0.4 mL(-1) x kg(-1) x h(-1)) on insulin secretion and insulin action in 15 elderly obese men; 7 glucose intolerant first-degree relatives of type 2 diabetic patients (impaired glucose tolerance [IGT] relatives) and 8...... healthy controls of similar age and body mass index (BMI). Intravenous glucose tolerance test (IVGTT) and a graded glucose infusion (dose-response test [DORE]) were performed to determine first phase insulin response and to explore the dose response relationship between glucose concentration and insulin...... secretion rates (ISR). ISR were calculated by deconvolution of plasma C-peptide concentrations. Insulin action was determined by performing a 120-minute hyperinsulinemic euglycemic clamp. All tests were performed 3 times, preceded by 0, 2, or 24 hours Intralipid infusion. Disposition indices (DI) were...

  14. Plasma Asprosin Concentrations Are Increased in Individuals with Glucose Dysregulation and Correlated with Insulin Resistance and First-Phase Insulin Secretion

    Directory of Open Access Journals (Sweden)

    Yuren Wang

    2018-01-01

    Full Text Available Background. Adipokines are reported to participate in many common pathologic processes of glucose dysregulation, such as insulin resistance, β-cell dysfunction, and chronic inflammation. Objective. To detect the concentrations of plasma asprosin in subjects with impaired glucose regulation (IGR and newly diagnosed type 2 diabetes (nT2DM and its relationship to parameters of glucose and lipid metabolism, insulin resistance, and pancreatic β-cell function. Methods. 143 eligible participants were included and were divided into three groups including normal glucose regulation (NGR, n=52, IGR (n=40, and nT2DM group (n=51. The intravenous glucose tolerance test (IVGTT and clinical and biochemical parameters were measured in all participants. Results. Plasma asprosin levels were higher in IGR (82.40 ± 91.06 ng/mL, P<0.001 and nT2DM (73.25 ± 91.69 ng/mL, P<0.001 groups compared with those in the NGR (16.22 ± 9.27 ng/mL group, especially in IGR subjects. Correlation analysis showed that plasma asprosin levels were positively correlated with waist circumference (Wc, fasting plasma glucose (FPG, postchallenge plasma glucose (2hPG, HbA1c, triglyceride (TG, and homeostasis model assessment for insulin resistance (HOMA-IR and negatively correlated with homeostasis model assessment for β-cell function (HOMA-β, area under the curve of the first-phase (0–10 min insulin secretion (AUC, acute insulin response (AIR, and glucose disposition index (GDI (all P<0.05. Multiple logistical regression analyses revealed that plasma asprosin concentrations were significantly correlated with IGR and nT2DM after controlling for age, sex, BMI, and WHR. Conclusions. Circulating asprosin might be a predictor of early diagnosis in DM and might be a potential therapeutic target for prediabetes and T2DM.

  15. Vitamin D deficiency impairs glucose-stimulated insulin secretion and increases insulin resistance by reducing PPAR-γ expression in nonobese Type 2 diabetic rats.

    Science.gov (United States)

    Park, Sunmin; Kim, Da Sol; Kang, Suna

    2016-01-01

    Human studies have provided relatively strong associations of poor vitamin D status with Type 2 diabetes but do not explain the nature of the association. Here, we explored the physiological pathways that may explain how vitamin D status modulates energy, lipid and glucose metabolisms in nonobese Type 2 diabetic rats. Goto-Kakizaki (GK) rats were fed high-fat diets containing 25 (VD-low), 1000 (VD-normal) or 10,000 (VD-high) cholecalciferol-IU/kg diet for 8 weeks. Energy expenditure, insulin resistance, insulin secretory capacity and lipid metabolism were measured. Serum 25-OH-D levels, an index of vitamin D status, increased dose dependently with dietary vitamin D. VD-low resulted in less fat oxidation without a significant difference in energy expenditure and less lean body mass in the abdomen and legs comparison to the VD-normal group. In comparison to VD-low, VD-normal had lower serum triglycerides and intracellular fat accumulation in the liver and skeletal muscles which was associated with down-regulation of the mRNA expressions of sterol regulatory element binding protein-1c and fatty acid synthase and up-regulation of gene expressions of peroxisome proliferator-activated receptors (PPAR)-α and carnitine palmitoyltransferase-1. In euglycemic hyperinsulinemic clamp, whole-body and hepatic insulin resistance was exacerbated in the VD-low group but not in the VD-normal group, possibly through decreasing hepatic insulin signaling and PPAR-γ expression in the adipocytes. In 3T3-L1 adipocytes 1,25-(OH)2-D (10 nM) increased triglyceride accumulation by elevating PPAR-γ expression and treatment with a PPAR-γ antagonist blocked the triglyceride deposition induced by 1,25-(OH)2-D treatment. VD-low impaired glucose-stimulated insulin secretion in hyperglycemic clamp and decreased β-cell mass by decreasing β-cell proliferation. In conclusion, vitamin D deficiency resulted in the dysregulation of glucose metabolism in GK rats by simultaneously increasing insulin

  16. BMT decreases HFD-induced weight gain associated with decreased preadipocyte number and insulin secretion.

    Directory of Open Access Journals (Sweden)

    Saeed Katiraei

    Full Text Available Experimental bone marrow transplantation (BMT in mice is commonly used to assess the role of immune cell-specific genes in various pathophysiological settings. The application of BMT in obesity research is hampered by the significant reduction in high-fat diet (HFD-induced obesity. We set out to characterize metabolic tissues that may be affected by the BMT procedure and impair the HFD-induced response. Male C57BL/6 mice underwent syngeneic BMT using lethal irradiation. After a recovery period of 8 weeks they were fed a low-fat diet (LFD or HFD for 16 weeks. HFD-induced obesity was reduced in mice after BMT as compared to HFD-fed control mice, characterized by both a reduced fat (-33%; p<0.01 and lean (-11%; p<0.01 mass, while food intake and energy expenditure were unaffected. As compared to control mice, BMT-treated mice had a reduced mature adipocyte volume (approx. -45%; p<0.05 and reduced numbers of preadipocytes (-38%; p<0.05 and macrophages (-62%; p<0.05 in subcutaneous, gonadal and visceral white adipose tissue. In BMT-treated mice, pancreas weight (-46%; p<0.01 was disproportionally decreased. This was associated with reduced plasma insulin (-68%; p<0.05 and C-peptide (-37%; p<0.01 levels and a delayed glucose clearance in BMT-treated mice on HFD as compared to control mice. In conclusion, the reduction in HFD-induced obesity after BMT in mice is at least partly due to alterations in the adipose tissue cell pool composition as well as to a decreased pancreatic secretion of the anabolic hormone insulin. These effects should be considered when interpreting results of experimental BMT in metabolic studies.

  17. Insulin sensitivity and insulin secretion at birth in intrauterine growth retarded infants.

    Science.gov (United States)

    Setia, Sajita; Sridhar, M G; Bhat, Vishnu; Chaturvedula, Lata; Vinayagamoorti, R; John, Mathew

    2006-06-01

    To study insulin sensitivity, secretion and relation of insulin levels with birth weight and ponderal index in intrauterine growth retarded (IUGR) infants at birth. We studied 30 IUGR and 30 healthy newborns born at term by vaginal delivery in Jipmer, Pondicherry, India. Cord blood was collected at the time of delivery for measurement of plasma glucose and insulin. When compared with healthy newborns, IUGR newborns had lower plasma glucose levels (mean 2.3+/-0.98 versus 4.1+/-0.51 mmol/L, p<0.001); lower plasma insulin levels (mean 4.5+/-2.64 versus 11.03+/-1.68 microU/L, p<0.001); higher insulin sensitivity calculated using G/I ratio (mean 11.6+/-5.1 versus 6.7+/-0.31, p<0.001), HOMA IS (mean 5.5+/-6.0 versus 0.53+/-0.15, p<0.001), and QUICKI (mean 0.47+/-0.12 versus 0.34+/-0.02, p<0.001); and decreased pancreatic beta-cell function test measured as I/G (mean 0.10+/-0.037 versus 0.15+/-0.006, p<0.001). A positive correlation was identified between insulin levels and birth weight in both the healthy control group (r2 = 0.17, p = 0.024) and IUGR group (r2 = 0.13, p = 0.048). However correlation of insulin levels with ponderal index was much more confident in both healthy control (r2 = 0.90, p<0.001) and IUGR groups (r2 = 0.28, p = 0.003). Insulin status correlated both with birth weight and ponderal index more confidently in control group than in IUGR group. At birth, IUGR infants are hypoglycaemic, hypoinsulinaemic and display increased insulin sensitivity and decreased pancreatic beta-cell function. Insulin levels correlate with ponderal index much more confidently than with birth weight.

  18. Integrative analysis of a cross-loci regulation network identifies App as a gene regulating insulin secretion from pancreatic islets.

    Directory of Open Access Journals (Sweden)

    Zhidong Tu

    Full Text Available Complex diseases result from molecular changes induced by multiple genetic factors and the environment. To derive a systems view of how genetic loci interact in the context of tissue-specific molecular networks, we constructed an F2 intercross comprised of >500 mice from diabetes-resistant (B6 and diabetes-susceptible (BTBR mouse strains made genetically obese by the Leptin(ob/ob mutation (Lep(ob. High-density genotypes, diabetes-related clinical traits, and whole-transcriptome expression profiling in five tissues (white adipose, liver, pancreatic islets, hypothalamus, and gastrocnemius muscle were determined for all mice. We performed an integrative analysis to investigate the inter-relationship among genetic factors, expression traits, and plasma insulin, a hallmark diabetes trait. Among five tissues under study, there are extensive protein-protein interactions between genes responding to different loci in adipose and pancreatic islets that potentially jointly participated in the regulation of plasma insulin. We developed a novel ranking scheme based on cross-loci protein-protein network topology and gene expression to assess each gene's potential to regulate plasma insulin. Unique candidate genes were identified in adipose tissue and islets. In islets, the Alzheimer's gene App was identified as a top candidate regulator. Islets from 17-week-old, but not 10-week-old, App knockout mice showed increased insulin secretion in response to glucose or a membrane-permeant cAMP analog, in agreement with the predictions of the network model. Our result provides a novel hypothesis on the mechanism for the connection between two aging-related diseases: Alzheimer's disease and type 2 diabetes.

  19. Mesenchymal Stem Cell Therapy in Diabetes Mellitus: Progress and Challenges

    OpenAIRE

    El-Badri, Nagwa; Ghoneim, Mohamed A.

    2013-01-01

    Advanced type 2 diabetes mellitus is associated with significant morbidity and mortality due to cardiovascular, nervous, and renal complications. Attempts to cure diabetes mellitus using islet transplantation have been successful in providing a source for insulin secreting cells. However, limited donors, graft rejection, the need for continued immune suppression, and exhaustion of the donor cell pool prompted the search for a more sustained source of insulin secreting cells. Stem cell therapy...

  20. L-leucine methyl ester stimulates insulin secretion and islet glutamate dehydrogenase

    DEFF Research Database (Denmark)

    Knudsen, P; Kofod, Hans; Lernmark, A

    1983-01-01

    Column perifusion of collagenase-isolated mouse pancreatic islets was used to study the dynamics of insulin release in experiments lasting for several hours. The methyl esters of L-leucine and L-arginine were synthesized. Whereas L-arginine methyl ester (L-arginine OMe) had no effect, L-leucine OMe...... stimulated the release of insulin. The effect of L-leucine OMe was maximal at 5 mmol/liter. Whereas the Km for glucose-stimulated insulin release was unaffected by 1 mmol/liter L-leucine OMe, the maximal release of D-glucose was increased by the amino acid derivative that appeared more effective than L......-leucine. L-Leucine OMe was also a potent stimulus of insulin release from the perfused mouse pancreas. In the presence of 10 mmol/liter L-glutamine, 1 mmol/liter L-leucine OMe induced a 50- to 75-fold increase in insulin release. A similar stimulatory effect was also observed in column-perifused RIN 5F cells...

  1. Impact of taurine depletion on glucose control and insulin secretion in mice.

    Science.gov (United States)

    Ito, Takashi; Yoshikawa, Natsumi; Ito, Hiromi; Schaffer, Stephen W

    2015-09-01

    Taurine, an endogenous sulfur-containing amino acid, is found in millimolar concentrations in mammalian tissue, and its tissue content is altered by diet, disease and aging. The effectiveness of taurine administration against obesity and its related diseases, including type 2 diabetes, has been well documented. However, the impact of taurine depletion on glucose metabolism and fat deposition has not been elucidated. In this study, we investigated the effect of taurine depletion (in the taurine transporter (TauT) knockout mouse model) on blood glucose control and high fat diet-induced obesity. TauT-knockout (TauTKO) mice exhibited lower body weight and abdominal fat mass when maintained on normal chow than wild-type (WT) mice. Blood glucose disposal after an intraperitoneal glucose injection was faster in TauTKO mice than in WT mice despite lower serum insulin levels. Islet beta-cells (insulin positive area) were also decreased in TauTKO mice compared to WT mice. Meanwhile, overnutrition by high fat (60% fat)-diet could lead to obesity in TauTKO mice despite lower body weight under normal chow diet condition, indicating nutrition in normal diet is not enough for TauTKO mice to maintain body weight comparable to WT mice. In conclusion, taurine depletion causes enhanced glucose disposal despite lowering insulin levels and lower body weight, implying deterioration in tissue energy metabolism. Copyright © 2015 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  2. High-fat diet with stress impaired islets' insulin secretion by reducing plasma estradiol and pancreatic GLUT2 protein levels in rats' proestrus phase.

    Science.gov (United States)

    Salimi, M; Zardooz, H; Khodagholi, F; Rostamkhani, F; Shaerzadeh, F

    2016-10-01

    This study was conducted to determine whether two estrus phases (proestrus and diestrus) in female rats may influence the metabolic response to a high-fat diet and/or stress, focusing on pancreatic insulin secretion and content. Animals were divided into high-fat and normal diet groups, then each group was subdivided into stress and non-stress groups, and finally, each one of these was divided into proestrus and diestrus subgroups. At the end of high-fat diet treatment, foot-shock stress was applied to the animals. Then, blood samples were taken to measure plasma factors. Finally, the pancreas was removed for determination of glucose transporter 2 (GLUT2) protein levels and assessment of insulin content and secretion of the isolated islets. In the normal and high-fat diet groups, stress increased plasma corticosterone concentration in both phases. In both study phases, high-fat diet consumption decreased estradiol and increased leptin plasma levels. In the high-fat diet group in response to high glucose concentration, a reduction in insulin secretion was observed in the proestrus phase compared with the same phase in the normal diet group in the presence and absence of stress. Also, high-fat diet decreased the insulin content of islets in the proestrus phase compared with the normal diet. High-fat diet and/or stress caused a reduction in islet GLUT2 protein levels in both phases. In conclusion, it seems possible that high-fat diet alone or combined with foot-shock, predispose female rats to impaired insulin secretion, at least in part, by interfering with estradiol levels in the proestrus phase and decreasing pancreatic GLUT2 protein levels.

  3. [Primary study on characteristics of insulin secretion rate, metabolic clearance rate and sensitivity in non-insulin-dependent diabetic subjects from multiplex diabetic pedigrees].

    Science.gov (United States)

    Ran, J; Cheng, H; Li, F

    2000-01-01

    To investigate the characteristics of insulin secretion rate (ISR), metabolic clearance rate (MCR-I) and sensitivity and to explore their relationship with obesity in non-insulin-dependent diabetic subjects from multiplex diabetic pedigrees (MDP). Fifteen subjects with normal glucose tolerance and 11 non-insulin-dependent diabetic patients from MDP were included in the study. Frequently sampled intravenous glucose tolerance test (FSIVGTT) was performed. Glucose, insulin (INS) and connecting-peptide (C-P) concentrations were measured. A computer procedure devised by our laboratory was used to calculate the value of ISR at each time point, then MCR-I was acquired. Insulin sensitivity index (SI) was calculated according to minimal model technique about glucose in FSIVGTT. The ISR curve in control group was biphasic, while in non-insulin. In non-insulin-dependent diabetic group, areas under the curves of C-P (AUCC) and ISR level (AUCS) measured during 0 approximately 16 min were 7.9 nmol.min(-1).L(-1) +/- 2.8 nmol.min(-1).L(-1), and 6.1 nmol +/- 2.2 nmol, respectively, which were significantly lower than those in control group 17.7 nmol.min(-1).L(-1) +/- 4.92 nmol.min(-1).L(-1) and 12.3 nmol +/- 3.9 nmol (P < 0.01). The two parameters were slightly higher than those in control group 155 nmol.min(-1).L(-1) +/- 44 nmol.min(-1).L(-1) vs 101 nmol.min(-1).L(-1) +/- 30 nmol.min(-1).L(-1) and 76 nmol +/- 26 nmol vs 54 nmol +/- 20.0 nmol (P < 0.05)measured during 16 approximately 180 min. There was no significant difference, between the two groups about the amount of insulin secretion during 3 hours (82 nmol +/- 28nmol vs 68 nmol +/- 21 nmol, P = 0.2). In control group, there were significant positive correlation, between AUCS, waist-hip ratio (WHR), and body surface area, (BSA) and significant negative correlation between MCR-I, SI and WHR, BSA (P < 0.01), and also between MCR-I and SI. In non-insulin-dependent diabetic group, AUCS were significantly correlated with body mass

  4. Decreased serum betatrophin levels correlate with improved fasting plasma glucose and insulin secretion capacity after Roux-en-Y gastric bypass in obese Chinese patients with type 2 diabetes: a 1-year follow-up.

    Science.gov (United States)

    Guo, Kaifeng; Yu, Haoyong; Lu, Junxi; Bao, Yuqian; Chen, Haibing; Jia, Weiping

    2016-08-01

    There is increasing evidence that serum betatrophin levels, a hormone derived from adipose tissue and liver, are elevated in type 2 diabetes (T2D). To investigate the relationships among betatrophin and metabolic control, insulin resistance, and pancreatic β-cell function in obese Chinese patients with T2D who underwent Roux-en-Y gastric bypass (RYGB). University hospital, China. This 1-year follow-up study included 34 obese individuals with T2D (18 males, 16 females) who underwent RYGB in our hospital. Anthropometric results, glucose levels, lipid profiles, and serum betatrophin levels were determined before and 1 year after RYGB. The serum betatrophin level decreased significantly after RYGB (72.0 ng/mL [33.4-180.9] versus 35.7 ng/mL [14.8-103.3]); Pfasting plasma glucose and negatively correlated with the changes in the 2-hour C-peptide/fasting C-peptide and homeostasis model of assessment of β-cell function (Pfasting plasma glucose (β = .586, Pfasting C-peptide (β = -.309, P = .021). Circulating betatrophin might be involved in the regulation of glucose control and insulin secretion in obese Chinese with T2D soon after RYGB. Copyright © 2016 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

  5. Genetic Markers of Insulin Sensitivity and Insulin Secretion Are Associated With Spontaneous Postnatal Growth and Response to Growth Hormone Treatment in Short SGA Children

    DEFF Research Database (Denmark)

    Jensen, Rikke Beck; Thankamony, Ajay; Day, Felix

    2015-01-01

    with spontaneous postnatal weight gain (regression coefficient [B]: 0.12 SD scores per allele; 95% confidence interval [CI], 0.01-0.23; P = .03) and also in response to GH therapy with first-year height velocity (B: 0.18 cm/y per allele; 95% CI, 0.02-0.35; P = .03) and change in IGF-1 (B: 0.17 SD scores per allele......PURPOSE: The wide heterogeneity in the early growth and metabolism of children born small for gestational age (SGA), both before and during GH therapy, may reflect common genetic variations related to insulin secretion or sensitivity. METHOD: Combined multiallele single nucleotide polymorphism......; 95% CI, 0.00-0.32; P = .03). The association with first-year height velocity was independent of reported predictors of response to GH therapy (adjusted P = .04). The insulin secretion allele score (GS-InSec) was positively associated with spontaneous postnatal height gain (B: 0.15; 95% CI, 0...

  6. Ethanolic Extract of Butea monosperma Leaves Elevate Blood Insulin Level in Type 2 Diabetic Rats, Stimulate Insulin Secretion in Isolated Rat Islets, and Enhance Hepatic Glycogen Formation

    Directory of Open Access Journals (Sweden)

    Mehdi Bin Samad

    2014-01-01

    Full Text Available We measured a vast range of parameters, in an attempt to further elucidate previously claimed antihyperglycemic activity of Butea monosperma. Our study clearly negates the possibility of antidiabetic activity by inhibited gastrointestinal enzyme action or by reduced glucose absorption. Reduction of fasting and postprandial glucose level was reconfirmed (P<0.05. Improved serum lipid profile via reduced low density lipoprotein (LDL, cholesterol, triglycerides (TG, and increased high density lipoprotein (HDL was also reestablished (P<0.05. Significant insulin secretagogue activity of B. monosperma was found in serum insulin assay of B. monosperma treated type 2 diabetic rats (P<0.01. This was further ascertained by our study on insulin secretion on isolated rat islets (P<0.05. Improved sensitivity of glucose was shown by the significant increase in hepatic glycogen deposition (P<0.05. Hence, we concluded that antihyperglycemic activity of B. monosperma was mediated by enhanced insulin secretion and enhanced glycogen formation in the liver.

  7. Fractalkine (CX3CL1, a new factor protecting β-cells against TNFα

    Directory of Open Access Journals (Sweden)

    Sabine Rutti

    2014-10-01

    Conclusions: We demonstrate for the first time that human islets express and secrete CX3CL1 and CX3CL1 impacts them by decreasing glucagon secretion without affecting insulin secretion. Moreover, CX3CL1 decreases basal apoptosis of human β-cells. We further demonstrate that CX3CL1 protects β-cells from the adverse effects of TNFα on their function by restoring the expression and phosphorylation of key proteins of the insulin secretion pathway.

  8. Effects of glucagon-like peptide 1 on counterregulatory hormone responses, cognitive functions, and insulin secretion during hyperinsulinemic, stepped hypoglycemic clamp experiments in healthy volunteers

    DEFF Research Database (Denmark)

    Nauck, Michael A; Heimesaat, Markus M; Behle, Kai

    2002-01-01

    and neuroglucopenic symptoms were assessed, and cognitive function was tested at each plateau. Insulin secretion rates were estimated by deconvolution (two-compartment model of C-peptide kinetics). At insulin concentrations of approximately 45 mU/liter, glucose infusion rates were similar with and without GLP-1 (P......Glucagon-like peptide 1 (GLP-1) and analogues are being evaluated as a new therapeutic principle for the treatment of type 2 diabetes. GLP-1 suppresses glucagon secretion, which could lead to disturbances of hypoglycemia counterregulation. This has, however, not been tested. Nine healthy volunteers.......97). The other counterregulatory hormones and autonomic or neuroglucopenic symptom scores increased, and cognitive functions decreased with decreasing glucose concentrations, but there were no significant differences comparing experiments with GLP-1 or placebo, except for a significant reduction of GH responses...

  9. GLP-1-(9-36) amide reduces blood glucose in anesthetized pigs by a mechanism that does not involve insulin secretion

    DEFF Research Database (Denmark)

    Deacon, Carolyn F; Plamboeck, Astrid; Møller, Søren

    2002-01-01

    impossible to assess its true efficacy in vivo. In chloralose-anesthetized pigs given valine-pyrrolidide (to block endogenous DPP IV activity), the independent effects of GLP-1-(7-36) amide on glucose and insulin responses to intravenous glucose were assessed, and the metabolite generated by DPP IV, GLP-1......-(9-36) amide, was investigated for any ability to influence these responses. GLP-1-(7-36) amide enhanced insulin secretion (P amide was without effect, either alone or when coinfused with GLP-1-(7-36) amide. In contrast, GLP-1-(9-36) amide did affect glucose responses (P...... amide (73 +/- 19 mmol x l(-1) x min; P amide (62 +/- 13 mmol x l(-1) x min; P amide + GLP-1-(9-36) amide (50 +/-13 mmol x l(-1) x min; P

  10. Bimodal effect on pancreatic β-cells of secretory products from normal or insulin-resistant human skeletal muscle

    DEFF Research Database (Denmark)

    Bouzakri, Karim; Plomgaard, Peter; Berney, Thierry

    2011-01-01

    Type 2 diabetes is characterized by insulin resistance with a relative deficiency in insulin secretion. This study explored the potential communication between insulin-resistant human skeletal muscle and primary (human and rat) β-cells.......Type 2 diabetes is characterized by insulin resistance with a relative deficiency in insulin secretion. This study explored the potential communication between insulin-resistant human skeletal muscle and primary (human and rat) β-cells....

  11. Effects of acute and chronic attenuation of postprandial hyperglycemia on postglucose-load endothelial function in insulin resistant individuals: is stimulation of first phase insulin secretion beneficial for the endothelial function?

    DEFF Research Database (Denmark)

    Major-Pedersen, A; Ihlemann, N; Hermann, T S

    2008-01-01

    The aim of the study is to determine if attenuation of postprandial hyperglycemia, by acutely and chronically enhancing postprandial insulin secretion in insulin-resistant individuals, improves the endothelial dysfunction. We assessed postoral glucose-load endothelial function in 56 insulin....... We found no relationship between postprandial hyperglycemia and post-OGL FMD....

  12. Improved pancreatic beta-cell function in type 2 diabetic patients after lifestyle-induced weight loss is related to glucose-dependent insulinotropic polypeptide

    DEFF Research Database (Denmark)

    Solomon, Thomas; Haus, Jacob M; Kelly, Karen R

    2010-01-01

    Restoration of insulin secretion is critical for the treatment of type 2 diabetes. Exercise and diet can alter glucose-induced insulin responses, but whether this is due to changes in beta-cell function per se is not clear. The mechanisms by which lifestyle intervention may modify insulin secretion...... in type 2 diabetes have also not been examined but may involve the incretin axis....

  13. Whole-exome sequencing for mutation detection in pediatric disorders of insulin secretion: Maturity onset diabetes of the young and congenital hyperinsulinism.

    Science.gov (United States)

    Johnson, S R; Leo, P J; McInerney-Leo, A M; Anderson, L K; Marshall, M; McGown, I; Newell, F; Brown, M A; Conwell, L S; Harris, M; Duncan, E L

    2018-06-01

    To assess the utility of whole-exome sequencing (WES) for mutation detection in maturity-onset diabetes of the young (MODY) and congenital hyperinsulinism (CHI). MODY and CHI are the two commonest monogenic disorders of glucose-regulated insulin secretion in childhood, with 13 causative genes known for MODY and 10 causative genes identified for CHI. The large number of potential genes makes comprehensive screening using traditional methods expensive and time-consuming. Ten subjects with MODY and five with CHI with known mutations underwent WES using two different exome capture kits (Nimblegen SeqCap EZ Human v3.0 Exome Enrichment Kit, Nextera Rapid Capture Exome Kit). Analysis was blinded to previously identified mutations, and included assessment for large deletions. The target capture of five exome capture technologies was also analyzed using sequencing data from >2800 unrelated samples. Four of five MODY mutations were identified using Nimblegen (including a large deletion in HNF1B). Although targeted, one mutation (in INS) had insufficient coverage for detection. Eleven of eleven mutations (six MODY, five CHI) were identified using Nextera Rapid (including the previously missed mutation). On reconciliation, all mutations concorded with previous data and no additional variants in MODY genes were detected. There were marked differences in the performance of the capture technologies. WES can be useful for screening for MODY/CHI mutations, detecting both point mutations and large deletions. However, capture technologies require careful selection. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Clustering effects on postprandial insulin secretion and sensitivity in response to meals with different fatty acid compositions.

    Science.gov (United States)

    Bermudez, Beatriz; Ortega-Gomez, Almudena; Varela, Lourdes M; Villar, Jose; Abia, Rocio; Muriana, Francisco J G; Lopez, Sergio

    2014-07-25

    Dietary fatty acids play a role in glucose homeostasis. The aim of this study was to assess the individual relationship between dietary saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids with postprandial β-cell function and insulin sensitivity in subjects with normal and high fasting triglycerides. We assessed postprandial β-cell function (by the insulinogenic index and the ratio of the insulin to glucose areas under the time-concentration curve) and insulin sensitivity (by the oral glucose and the minimal model insulin sensitivity indices) over four nonconsecutive, randomly assigned, high-fat meals containing a panel of SFA (palmitic and stearic acids), MUFA (palmitoleic and oleic acids) and PUFA (linoleic and α-linolenic acids) in 14 subjects with normal and in 14 subjects with high fasting triglycerides. The proportions of each fatty acid in the meals and the values for surrogate measures of postprandial β-cell function and insulin sensitivity were subjected to a Pearson correlation and hierarchical cluster analysis, which revealed two classes of dietary fatty acids for regulating postprandial glucose homeostasis. We successfully discriminated the adverse effects of SFA palmitic acid from the beneficial effects of MUFA oleic acid on postprandial β-cell function (r ≥ 0.84 for SFA palmitic acid and r ≥ -0.71 for MUFA oleic acid; P < 0.05) and insulin sensitivity (r ≥ -0.92 for SFA palmitic acid and r ≥ 0.89 for MUFA oleic acid; P < 0.001) both in subjects with normal and high fasting triglycerides. In conclusion, dietary MUFA oleic acid, in contrast to SFA palmitic acid, favours the tuning towards better postprandial glycaemic control in subjects with normal and high fasting triglycerides.

  15. L-rhamnose as a source of colonic propionate inhibits insulin secretion but does not influence measures of appetite or food intake.

    Science.gov (United States)

    Darzi, Julia; Frost, Gary S; Swann, Jonathan R; Costabile, Adele; Robertson, M Denise

    2016-03-01

    Activation of free fatty acid receptor (FFAR)2 and FFAR3 via colonic short-chain fatty acids, particularly propionate, are postulated to explain observed inverse associations between dietary fiber intake and body weight. Propionate is reported as the predominant colonic fermentation product from l-rhamnose, a natural monosaccharide that resists digestion and absorption reaching the colon intact, while effects of long-chain inulin on appetite have not been extensively investigated. In this single-blind randomized crossover study, healthy unrestrained eaters (n = 13) ingested 25.5 g/d l-rhamnose, 22.4 g/d inulin or no supplement (control) alongside a standardized breakfast and lunch, following a 6-d run-in to investigate if appetite was inhibited. Postprandial qualitative appetite, breath hydrogen, and plasma glucose, insulin, triglycerides and non-esterified fatty acids were assessed for 420 min, then an ad libitum meal was provided. Significant treatment x time effects were found for postprandial insulin (P = 0.009) and non-esterified fatty acids (P = 0.046) with a significantly lower insulin response for l-rhamnose (P = 0.023) than control. No differences between treatments were found for quantitative and qualitative appetite measures, although significant treatment x time effects for meal desire (P = 0.008) and desire to eat sweet (P = 0.036) were found. Breath hydrogen was significantly higher with inulin (P = 0.001) and l-rhamnose (P = 0.009) than control, indicating colonic fermentation. These findings suggest l-rhamnose may inhibit postprandial insulin secretion, however neither l-rhamnose or inulin influenced appetite. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Balanites aegyptiaca ameliorates insulin secretion and decreases pancreatic apoptosis in diabetic rats: Role of SAPK/JNK pathway.

    Science.gov (United States)

    Hassanin, Kamel M A; Mahmoud, Mohamed O; Hassan, Hossam M; Abdel-Razik, Abdel-Razik H; Aziz, Lourin N; Rateb, Mostafa E

    2018-06-01

    SAPK-JNK pathway performs a significant role in the pathogenesis of type 2 diabetes. Balanites aegyptiaca (BA) is used as an anti-diabetic agent in folk medicine however its hypoglycemic mechanism is not fully elucidated. The current study aimed to evaluate the effect of crude extract, butanol, and dichloromethane fractions from BA on the stress-activated protein kinase/c-Jun N-terminal kinase (SAPK-JNK) pathway in experimental diabetic rats. Six groups of male Wistar rats were included: normal control, diabetic, diabetic rats treated with crude, butanol or dichloromethane fraction from BA (50 mg/kg BW) and diabetic rats treated with gliclazide as a reference drug for one month. Our results suggested a protective role of treatment of diabetic rats with BA against oxidative stress-induced SAPK-JNK pathway. Moreover, BA treatment produced a reduction in plasma glucose, HbA 1c , lactic acid, lipid profile, malondialdehyde levels and produced an increase in insulin, reduced glutathione levels, catalase and superoxide dismutase activities compared with untreated diabetic rats. Moreover, it decreased apoptosis signal-regulating kinase 1, c-Jun N-terminal kinase 1, protein 53 and increased insulin receptor substrate 1 in rat pancreas while it increased glucose transporter 4 in rat muscle. Analysis of BA extracts by LC-HRMS revealed the presence of different saponins with reported hypoglycemic effect. In conclusion, BA exerted hypoglycemic, hypolipidemic, insulinotropic and antioxidant effects. Additionally, it reduced apoptosis in pancreatic β-cells and increased glucose uptake in muscle. These results suggest that the hypoglycemic effect of BA is due to the inhibition of the SAPK-JNK pathway. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  17. Effects of zinc supplementation and zinc chelation on in vitro β-cell function in INS-1E cells

    DEFF Research Database (Denmark)

    Nygaard, Sanne Bjørn; Larsen, Agnete; Knuhtsen, Astrid

    2014-01-01

    BACKGROUND: Zinc is essential for the activities of pancreatic β-cells, especially insulin storage and secretion. Insulin secretion leads to co-release of zinc which contributes to the paracrine communication in the pancreatic islets. Zinc-transporting proteins (zinc-regulated transporter, iron......-regulated transporter-like proteins [ZIPs] and zinc transporters [ZnTs]) and metal-buffering proteins (metallothioneins, MTs) tightly regulate intracellular zinc homeostasis. The present study investigated how modulation of cellular zinc availability affects β-cell function using INS-1E cells. RESULTS: Using INS-1E...... cells, we found that zinc supplementation and zinc chelation had significant effects on insulin content and insulin secretion. Supplemental zinc within the physiological concentration range induced insulin secretion. Insulin content was reduced by zinc chelation with N,N,N',N-tektrakis(2-pyridylmethyl...

  18. Zinc Supplementation Does Not Alter Indicators of Insulin Secretion and Sensitivity in Black and White Female Adolescents.

    Science.gov (United States)

    Lobene, Andrea J; Kindler, Joseph M; Jenkins, Nathan T; Pollock, Norman K; Laing, Emma M; Grider, Arthur; Lewis, Richard D

    2017-07-01

    Background: Zinc is a micronutrient involved in the production of, and peripheral sensitivity to, pancreatic β cell-derived insulin. To our knowledge, the effect of zinc supplementation on insulin outcomes, and potential risk of diabetes, in otherwise healthy children in the United States has not been investigated. Objective: The objective of this study was to determine the influence of zinc supplementation on insulin outcomes in black and white girls in the early stages of adolescence. A secondary objective was to determine relations between baseline zinc concentrations and insulin outcomes. Methods: Healthy black and white girls aged 9-11 y were randomly assigned to daily supplementation of zinc (9 mg elemental Zn/d; n = 75; blacks: n = 35) or placebo ( n = 72; blacks: n = 32) for 4 wk. Fasting serum insulin, glucose, and C-peptide were assessed at baseline and at 4 wk. C-peptide and glucose values were used to calculate the computer model-derived homeostatic model assessment of insulin resistance (HOMA2-IR). Changes in outcome measures were compared by using repeated-measures, mixed-model ANOVA. Results: Baseline plasma zinc was not correlated with C-peptide ( r = -0.07), insulin ( r = -0.06), or HOMA2-IR ( r = -0.09) (all P > 0.05) after controlling for race and age. Treatment × time interactions for C-peptide and HOMA2-IR were not significant (both P > 0.05). Although the treatment × race × time interactions for C-peptide and HOMA2-IR were not significant (both P = 0.08), black girls who received the placebo experienced slight increases in C-peptide (15.7%) and HOMA2-IR (17.7%) ( P = 0.06). Conclusions: Four weeks of zinc supplementation had no effect on insulin outcomes in healthy black and white early-adolescent girls, although C-peptide and HOMA2-IR tended to increase in black girls who received placebo. Additional trials that are appropriately powered should further explore the effect of zinc on markers of diabetes risk, and whether race affects this

  19. [Factors causing damage and destruction of beta-cells of the islets of Langerhans in the pancreas].

    Science.gov (United States)

    Anděl, Michal; Němcová, Vlasta; Pavlíková, Nela; Urbanová, Jana; Cecháková, Marie; Havlová, Andrea; Straková, Radka; Večeřová, Livia; Mandys, Václav; Kovář, Jan; Heneberg, Petr; Trnka, Jan; Polák, Jan

    2014-09-01

    Insulin secretion in patients with manifested diabetes mellitus tends to disappear months to decades after the diagnosis, which is a clear sign of a gradual loss of pancreatic islet beta-cells. In our sample of 30 type 2 diabetic patients, whose disease manifested between 30 and 45 years of age, about a half have retained or even increased insulin secretion 30 years later, while the other half exhibit a much diminished or lost insulin secretion. Factors that can damage or destroy beta-cells can be divided into the following groups: Metabolic factors: hyperglycemia and glucotoxicity, lipotoxicity, hypoxia, reactive oxygen species; Pharmacological factors: antimicrobial medication pentamidine, SSRI antidepressants; Factors related to impaired insulin secretion: MODY type diabetes; Environmental toxic factors: rat poison Vacor, streptozotocin, polychlorinated and polybrominated hydrocarbons; Disorders of the exocrine pancreas: tumor infiltration, fibrous infiltration, chronic pancreatitis, cystic fibrosis; Infections, inflammation, autoimmunity, viral factors: Coxsackie viruses, H1N1 influenza, enteroviruses. We are currently working on finding other factors leading to beta-cell damage, studying their effect on apoptosis and necrosis and looking for possible protective factors to prevent this damage. We our increasing knowledge about the mechanisms of beta-cell damage and destruction we come ever closer to suggest measures for their prevention. In this review we offer a brief and simplified summary of some of the findings related to this area.Key words: pancreatic islet beta-cells of Langerhans - factors damaging or destroying beta-cells - insulin secretion.

  20. Glucemia, insulinemia y secreción de insulina en ratas prepúberes hiperandrogenizadas e hiperestrogenizadas Glycemia, insulinemia and insulin secretion in prepubescent rats receiving high doses of androgens and strogens

    Directory of Open Access Journals (Sweden)

    Aimée Álvarez Álvarez

    2001-04-01

    Full Text Available Se estudió el efecto de una sobredosis de enantato de testosterona y de benzoato de estradiol en ratas machos prepúberes, sobre el comportamiento de la glucemia y la insulinemia in vivo, durante una prueba de tolerancia a la glucosa. Adicionalmente se exploró, in vitro, la capacidad de secreción de insulina estimulada por glucosa de los islotes de Langerhans de estas ratas hiperandrogenizadas e hiperestrogenizadas. Se encontró que la hiperandrogenización se acompañaba de un deterioro de la sensibilidad a la insulina, con hiperinsulinemia, que no se corresponde con un aumento de la capacidad de secreción de insulina de los islotes de Langerhans. Sin embargo, se comprobó que la hiperestrogenización no indujo cambios en los perfiles de glucemia, ni de insulinemia, ni en la capacidad de secreción de insulina de los islotes de Langerhans de este grupo de ratas hiperestrogenizadas.The effect of an overdose of testosterone heptanoate and estradiol in male prepubescent rats on the behavior of glycemia and insulinemia was studied in vivo during a glucose tolerance test. The capacity of insulin secretion stimulated by glucose from the islets of Langerhans of these rats that were administered a high dose of androgens and estrogens was explored in vitro. It was found that the high level of circulating androgens was accompanied by a deterioration of sensitivity to insulin with hyperinsulinemia that does not correspond to an increase of the insulin secreting capacity of the islets of Langerhans. However, it was demonstrated that the high level of circulating estrogens did not produce changes either in the glycemia and insulinemia profiles or in the insulin secreting capacity of the islets of Langerhans in this group of rats that received an elevated dose of estrogens.

  1. Simulated Cholinergic Reinnervation of β (INS-1 Cells: Antidiabetic Utility of Heterotypic Pseudoislets Containing β Cell and Cholinergic Cell

    Directory of Open Access Journals (Sweden)

    Ao Jiao

    2018-01-01

    Full Text Available Cholinergic neurons can functionally support pancreatic islets in controlling blood sugar levels. However, in islet transplantation, the level of cholinergic reinnervation is significantly lower compared to orthotopic pancreatic islets. This abnormal reinnervation affects the survival and function of islet grafts. In this study, the cholinergic reinnervation of beta cells was simulated by 2D and 3D coculture of INS-1 and NG108-15 cells. In 2D culture conditions, 20 mM glucose induced a 1.24-fold increase (p<0.0001 in insulin secretion from the coculture group, while in the 3D culture condition, a 1.78-fold increase (p<0.0001 in insulin secretion from heterotypic pseudoislet group was observed. Glucose-stimulated insulin secretion (GSIS from 2D INS-1 cells showed minimal changes when compared to 3D structures. E-cadherin expressed in INS-1 and NG108-15 cells was the key adhesion molecule for the formation of heterotypic pseudoislets. NG108-15 cells hardly affected the proliferation of INS-1 cells in vitro. Heterotypic pseudoislet transplantation recipient mice reverted to normoglycemic levels faster and had a greater blood glucose clearance compared to INS-1 pseudoislet recipient mice. In conclusion, cholinergic cells can promote insulin-secreting cells to function better in vitro and in vivo and E-cadherin plays an important role in the formation of heterotypic pseudoislets.

  2. Impact of 9 days of bed rest on hepatic and peripheral insulin action, insulin secretion, and whole-body lipolysis in healthy young male offspring of patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Alibegovic, Amra C; Højbjerre, Lise; Sonne, Mette P

    2009-01-01

    decrease in whole-body insulin sensitivity in both groups. Hepatic insulin resistance was elevated in FDR subjects prior to bed rest and was significantly augmented by bed rest in FDR (P ... deteriorates with 9 days of bed rest, converging toward similar degrees of whole-body insulin resistance. FDR subjects exhibit hepatic insulin resistance (HIR), which, in contrast to CON subjects, deteriorates in response to physical inactivity. FDR subjects exhibit reduced insulin secretion when seen...... subjects, with no significant differences between the groups. Insulin resistance induced by bed rest was fully accounted for by the impairment of nonoxidative glucose metabolism in both groups (overall P resistant FDR and healthy CON subjects...

  3. Exocrine cell-derived microparticles in response to lipopolysaccharide promote endocrine dysfunction in cystic fibrosis.

    Science.gov (United States)

    Constantinescu, Andrei Alexandru; Gleizes, Céline; Alhosin, Mahmoud; Yala, Elhassan; Zobairi, Fatiha; Leclercq, Alexandre; Stoian, Gheorghe; Mitrea, Ioan Liviu; Prévost, Gilles; Toti, Florence; Kessler, Laurence

    2014-03-01

    Diabetes in cystic fibrosis (CF) is a result of exocrine pancreas alteration followed by endocrine dysfunction at a later stage. Microparticles (MPs) are plasma membrane fragments shed from stimulated or damaged cells that act as cellular effectors. Our aim was to identify a new form of interaction between exocrine and endocrine pancreatic cells mediated by exocrine MPs, in the context of recurrent infection in CF. MPs from either human exocrine CFTRΔF508-mutated (CFPAC-1) cells or exocrine normal pancreatic (PANC-1) cells were collected after treatment by LPS from Pseudomonas aeruginosa and applied to rat endocrine normal insulin-secreting RIN-m5F cells. MP membrane integration in target cells was established by confocal microscopy and flow cytometry using PKH26 lipid probe. Apoptosis, lysosomal activity, insulin secretion were measured after 18 h. MP-mediated NF-κB activation was measured in HEK-Blue reporter cells by SEAP reporter gene system and in RIN-m5F cells by Western blot. In endocrine normal cells, CFTR inhibition was achieved using Inhibitor-172. Compared to PANC-1, MPs from CFPAC-1 significantly reduced insulin secretion and lysosomal activity in RIN-m5F. MPs induced NF-κB activation by increasing the level of IκB phosphorylation. Moreover, the inhibition of NF-κB activation using specific inhibitors was associated with a restored insulin secretion. Interestingly, CFTR inhibition in normal RIN-m5F cells promoted apoptosis and decreased insulin secretion. During recurrent infections associated with CF, exocrine MPs may contribute to endocrine cell dysfunction via NF-κB pathways. Membrane CFTR dysfunction is associated with decreased insulin secretion. © 2013. Published by Elsevier B.V. on behalf of European Cystic Fibrosis Society. All rights reserved.

  4. Skeletal muscle to pancreatic β-cell cross-talk

    DEFF Research Database (Denmark)

    Christensen, Camilla S; P. Christensen, Dan; Lundh, Morten

    2015-01-01

    CONTEXT: Mechanisms explaining exercise-induced β-cell health are unknown. OBJECTIVE: To define the role of muscle contraction and acute exercise-derived soluble humoral mediators on β-cell health. DESIGN: In vitro models. SETTING: University. PARTICIPANTS: Healthy subjects. INTERVENTION...... insulin secretion in the absence of IL-1β+IFN-γ. CONCLUSIONS: Unidentified circulating humoral mediators released during exercise prevent proinflammatory cytokine-induced β-cell apoptosis. Muscle-derived mediators released during exercise suppress β-cell insulin secretion. Furthermore, muscle-derived IL-6...

  5. The EndoC-βH1 cell line is a valid model of human beta cells and applicable for screenings to identify novel drug target candidates

    Directory of Open Access Journals (Sweden)

    Violeta Georgieva Tsonkova

    2018-02-01

    Full Text Available Objective: To characterize the EndoC-βH1 cell line as a model for human beta cells and evaluate its beta cell functionality, focusing on insulin secretion, proliferation, apoptosis and ER stress, with the objective to assess its potential as a screening platform for identification of novel anti-diabetic drug candidates. Methods: EndoC-βH1 was transplanted into mice for validation of in vivo functionality. Insulin secretion was evaluated in cells cultured as monolayer and as pseudoislets, as well as in diabetic mice. Cytokine induced apoptosis, glucolipotoxicity, and ER stress responses were assessed. Beta cell relevant mRNA and protein expression were investigated by qPCR and antibody staining. Hundreds of proteins or peptides were tested for their effect on insulin secretion and proliferation. Results: Transplantation of EndoC-βH1 cells restored normoglycemia in streptozotocin induced diabetic mice. Both in vitro and in vivo, we observed a clear insulin response to glucose, and, in vitro, we found a significant increase in insulin secretion from EndoC-βH1 pseudoislets compared to monolayer cultures for both glucose and incretins.Apoptosis and ER stress were inducible in the cells and caspase 3/7 activity was elevated in response to cytokines, but not affected by the saturated fatty acid palmitate.By screening of various proteins and peptides, we found Bombesin (BB receptor agonists and Pituitary Adenylate Cyclase-Activating Polypeptides (PACAP to significantly induce insulin secretion and the proteins SerpinA6, STC1, and APOH to significantly stimulate proliferation.ER stress was readily induced by Tunicamycin and resulted in a reduction of insulin mRNA. Somatostatin (SST was found to be expressed by 1% of the cells and manipulation of the SST receptors was found to significantly affect insulin secretion. Conclusions: Overall, the EndoC-βH1 cells strongly resemble human islet beta cells in terms of glucose and incretin stimulated

  6. Glycogen metabolism in the glucose-sensing and supply-driven β-cell.

    Science.gov (United States)

    Andersson, Lotta E; Nicholas, Lisa M; Filipsson, Karin; Sun, Jiangming; Medina, Anya; Al-Majdoub, Mahmoud; Fex, Malin; Mulder, Hindrik; Spégel, Peter

    2016-12-01

    Glycogen metabolism in β-cells may affect downstream metabolic pathways controlling insulin release. We examined glycogen metabolism in human islets and in the rodent-derived INS-1 832/13 β-cells and found them to express the same isoforms of key enzymes required for glycogen metabolism. Our findings indicate that glycogenesis is insulin-independent but influenced by extracellular glucose concentrations. Levels of glycogen synthase decrease with increasing glucose concentrations, paralleling accumulation of glycogen. We did not find cAMP-elicited glycogenolysis and insulin secretion to be causally related. In conclusion, our results reveal regulated glycogen metabolism in human islets and insulin-secreting cells. Whether glycogen metabolism affects insulin secretion under physiological conditions remains to be determined. © 2016 Federation of European Biochemical Societies.

  7. Pancreatic beta-cell lipotoxicity induced by overexpression of hormone-sensitive lipase

    DEFF Research Database (Denmark)

    Winzell, Maria Sörhede; Svensson, Håkan; Enerbäck, Sven

    2003-01-01

    Lipid perturbations associated with triglyceride overstorage in beta-cells impair insulin secretion, a process termed lipotoxicity. To assess the role of hormone-sensitive lipase, which is expressed and enzymatically active in beta-cells, in the development of lipotoxicity, we generated transgenic...... mice overexpressing hormone-sensitive lipase specifically in beta-cells. Transgenic mice developed glucose intolerance and severely blunted glucose-stimulated insulin secretion when challenged with a high-fat diet. As expected, both lipase activity and forskolin-stimulated lipolysis was increased...

  8. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial.

    Science.gov (United States)

    Gardner, Christopher D; Trepanowski, John F; Del Gobbo, Liana C; Hauser, Michelle E; Rigdon, Joseph; Ioannidis, John P A; Desai, Manisha; King, Abby C

    2018-02-20

    Dietary modification remains key to successful weight loss. Yet, no one dietary strategy is consistently superior to others for the general population. Previous research suggests genotype or insulin-glucose dynamics may modify the effects of diets. To determine the effect of a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet on weight change and if genotype pattern or insulin secretion are related to the dietary effects on weight loss. The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial included 609 adults aged 18 to 50 years without diabetes with a body mass index between 28 and 40. The trial enrollment was from January 29, 2013, through April 14, 2015; the date of final follow-up was May 16, 2016. Participants were randomized to the 12-month HLF or HLC diet. The study also tested whether 3 single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss. Health educators delivered the behavior modification intervention to HLF (n = 305) and HLC (n = 304) participants via 22 diet-specific small group sessions administered over 12 months. The sessions focused on ways to achieve the lowest fat or carbohydrate intake that could be maintained long-term and emphasized diet quality. Primary outcome was 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss. Among 609 participants randomized (mean age, 40 [SD, 7] years; 57% women; mean body mass index, 33 [SD, 3]; 244 [40%] had a low-fat genotype; 180 [30%] had a low-carbohydrate genotype; mean baseline INS-30, 93 μIU/mL), 481 (79%) completed the trial. In the HLF vs HLC diets, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates

  9. The role of polyunsaturated fatty acids (n-3 PUFAs) on the pancreatic β-cells and insulin action.

    Science.gov (United States)

    Baynes, Habtamu Wondifraw; Mideksa, Seifu; Ambachew, Sintayehu

    2018-03-14

    Polyunsaturated Fatty acids have multiple effects in peripheral tissues and pancreatic beta cell function. The n-3 Polyunsaturated Fatty acids prevent and reverse high-fat-diet induced adipose tissue inflammation and insulin resistance. Insulin secretion is stimulated by glucose, amino acids, and glucagon- like peptide-1 in tissue containing high levels of n-3 Polyunsaturated Fatty acids than lower level of n-3 Polyunsaturated Fatty acids. Also, n-3 Polyunsaturated Fatty acids led to decreased production of prostaglandin, which in turn contributed to the elevation of insulin secretion. N-3 polyunsaturated fatty acids prevent cytokine-induced cell death in pancreatic islets. Supplementation of n-3 Polyunsaturated Fatty acids for human subjects prevent beta cell destruction and insulin resistance. It also enhances insulin secretion, reduction in lipid profiles and glucose concentration particularly in type II diabetes patients. Therefore there should be a focus on the treatment mechanism of insulin related obesity and diabetes by n-3 polyunsaturated fatty acids.

  10. Mathematical model of the glucose-insulin regulatory system: From the bursting electrical activity in pancreatic β-cells to the glucose dynamics in the whole body

    Science.gov (United States)

    Han, Kyungreem; Kang, Hyuk; Choi, M. Y.; Kim, Jinwoong; Lee, Myung-Shik

    2012-10-01

    A theoretical approach to the glucose-insulin regulatory system is presented. By means of integrated mathematical modeling and extensive numerical simulations, we probe the cell-level dynamics of the membrane potential, intracellular Ca2+ concentration, and insulin secretion in pancreatic β-cells, together with the whole-body level glucose-insulin dynamics in the liver, brain, muscle, and adipose tissues. In particular, the three oscillatory modes of insulin secretion are reproduced successfully. Such comprehensive mathematical modeling may provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination.

  11. The T-allele of TCF7L2 rs7903146 associates with a reduced compensation of insulin secretion for insulin resistance induced by 9 days of bed rest

    DEFF Research Database (Denmark)

    Alibegovic, Amra C; Sonne, Mette P; Højbjerre, Lise

    2010-01-01

    of FPIR in response to insulin resistance induced by bed rest was lower in carriers of the T-allele (P hepatic insulin resistance......OBJECTIVE: The aim of this study was to determine whether the type 2 diabetes-associated T-allele of transcription factor 7-like 2 (TCF7L2) rs7903146 associates with impaired insulin secretion to compensate for insulin resistance induced by bed rest. RESEARCH DESIGN AND METHODS: A total of 38....... The genetic analyses were done assuming a dominant model of inheritance. RESULTS: The first-phase insulin response (FPIR) was significantly lower in carriers of the T-allele compared with carriers of the CC genotype before bed rest, with and without correction for insulin resistance. The incremental rise...

  12. Glucagon like peptide-1-induced glucose metabolism in differentiated human muscle satellite cells is attenuated by hyperglycemia

    DEFF Research Database (Denmark)

    Green, Charlotte J; Henriksen, Tora I; Pedersen, Bente K

    2012-01-01

    Glucagon like peptide-1 (GLP-1) stimulates insulin secretion from the pancreas but also has extra-pancreatic effects. GLP-1 may stimulate glucose uptake in cultured muscle cells but the mechanism is not clearly defined. Furthermore, while the pancreatic effects of GLP-1 are glucose-dependent, the......Glucagon like peptide-1 (GLP-1) stimulates insulin secretion from the pancreas but also has extra-pancreatic effects. GLP-1 may stimulate glucose uptake in cultured muscle cells but the mechanism is not clearly defined. Furthermore, while the pancreatic effects of GLP-1 are glucose...

  13. Dynamic Changes in the Protein Localization in the Nuclear Environment in Pancreatic β-Cell after Brief Glucose Stimulation

    DEFF Research Database (Denmark)

    Kang, Taewook; Jensen, Pia; Solovyeva, Vita

    2018-01-01

    , we identified 20 components of the nuclear organization processes, including nuclear pore organization, ribonucleoprotein complex, and pre-mRNA transcription. We found alteration of the nuclear pore complex, together with calcium/calmodulin-binding chaperones that facilitate protein and RNA import......Characterization of molecular mechanisms underlying pancreatic β-cell function in relation to glucose-stimulated insulin secretion is incomplete, especially with respect to global response in the nuclear environment. We focus on the characterization of proteins in the nuclear environment of β...... the nucleus and the cytoplasm is an important process, highly involved in the initial molecular mechanism underlying glucose-stimulated insulin secretion in pancreatic β-cells....

  14. The MDM2-p53-pyruvate carboxylase signalling axis couples mitochondrial metabolism to glucose-stimulated insulin secretion in pancreatic β-cells

    DEFF Research Database (Denmark)

    Li, Xiaomu; Cheng, Kenneth K. Y.; Liu, Zhuohao

    2016-01-01

    deletion or pharmacological inhibition of its negative regulator MDM2, impairs GSIS, leading to glucose intolerance in mice. Mechanistically, p53 activation represses the expression of the mitochondrial enzyme pyruvate carboxylase (PC), resulting in diminished production of the TCA cycle intermediates...

  15. Characterization of P4 ATPase Phospholipid Translocases (Flippases) in Human and Rat Pancreatic Beta Cells: THEIR GENE SILENCING INHIBITS INSULIN SECRETION

    NARCIS (Netherlands)

    Ansari, Israr-Ul H.; Longacre, Melissa J.; Paulusma, Coen C.; Stoker, Scott W.; Kendrick, Mindy A.; MacDonald, Michael J.

    2015-01-01

    The negative charge of phosphatidylserine in lipid bilayers of secretory vesicles and plasma membranes couples the domains of positively charged amino acids of secretory vesicle SNARE proteins with similar domains of plasma membrane SNARE proteins enhancing fusion of the two membranes to promote

  16. Bioportide: an emergent concept of bioactive cell-penetrating peptides

    Czech Academy of Sciences Publication Activity Database

    Howl, J.; Matou-Nasri, S.; West, D. C.; Farquhar, M.; Slaninová, Jiřina; Ostenson, C. G.; Zorko, M.; Ostlund, P.; Kumar, S.; Langel, U.; McKeating, J.; Jones, S.

    2012-01-01

    Roč. 69, č. 17 (2012), s. 2951-2966 ISSN 1420-682X Institutional research plan: CEZ:AV0Z40550506 Keywords : angiogenesis * bioportide * cell-penetrating peptide * second messenger * insulin secretion Subject RIV: CE - Biochemistry Impact factor: 5.615, year: 2012

  17. Preganglionic innervation of the pancreas islet cells in the rat

    NARCIS (Netherlands)

    LUITEN, PGM; TERHORST, GJ; KOOPMANS, SJ; RIETBERG, M; STEFFENS, AB

    1984-01-01

    The position and number of preganglionic somata innervating the insulin-secreting β-cells of the endocrine pancreas were investigated in Wistar rats. This question was approached by comparing the innervation of the pancreas of normal rats with the innervation of the pancreas in alloxan-induced

  18. Pancreatic beta-cell overexpression of the glucagon receptor gene results in enhanced beta-cell function and mass

    DEFF Research Database (Denmark)

    Gelling, Richard W; Vuguin, Patricia M; Du, Xiu Quan

    2009-01-01

    in vivo, we generated mice overexpressing the Gcgr specifically on pancreatic beta-cells (RIP-Gcgr). In vivo and in vitro insulin secretion in response to glucagon and glucose was increased 1.7- to 3.9-fold in RIP-Gcgr mice compared with controls. Consistent with the observed increase in insulin release...

  19. The EndoC-βH1 cell line is a valid model of human beta cells and applicable for screenings to identify novel drug target candidates.

    Science.gov (United States)

    Tsonkova, Violeta Georgieva; Sand, Fredrik Wolfhagen; Wolf, Xenia Asbæk; Grunnet, Lars Groth; Kirstine Ringgaard, Anna; Ingvorsen, Camilla; Winkel, Louise; Kalisz, Mark; Dalgaard, Kevin; Bruun, Christine; Fels, Johannes Josef; Helgstrand, Charlotte; Hastrup, Sven; Öberg, Fredrik Kryh; Vernet, Erik; Sandrini, Michael Paolo Bastner; Shaw, Allan Christian; Jessen, Carsten; Grønborg, Mads; Hald, Jacob; Willenbrock, Hanni; Madsen, Dennis; Wernersson, Rasmus; Hansson, Lena; Jensen, Jan Nygaard; Plesner, Annette; Alanentalo, Tomas; Petersen, Maja Borup Kjær; Grapin-Botton, Anne; Honoré, Christian; Ahnfelt-Rønne, Jonas; Hecksher-Sørensen, Jacob; Ravassard, Philippe; Madsen, Ole D; Rescan, Claude; Frogne, Thomas

    2018-02-01

    To characterize the EndoC-βH1 cell line as a model for human beta cells and evaluate its beta cell functionality, focusing on insulin secretion, proliferation, apoptosis and ER stress, with the objective to assess its potential as a screening platform for identification of novel anti-diabetic drug candidates. EndoC-βH1 was transplanted into mice for validation of in vivo functionality. Insulin secretion was evaluated in cells cultured as monolayer and as pseudoislets, as well as in diabetic mice. Cytokine induced apoptosis, glucolipotoxicity, and ER stress responses were assessed. Beta cell relevant mRNA and protein expression were investigated by qPCR and antibody staining. Hundreds of proteins or peptides were tested for their effect on insulin secretion and proliferation. Transplantation of EndoC-βH1 cells restored normoglycemia in streptozotocin induced diabetic mice. Both in vitro and in vivo, we observed a clear insulin response to glucose, and, in vitro, we found a significant increase in insulin secretion from EndoC-βH1 pseudoislets compared to monolayer cultures for both glucose and incretins. Apoptosis and ER stress were inducible in the cells and caspase 3/7 activity was elevated in response to cytokines, but not affected by the saturated fatty acid palmitate. By screening of various proteins and peptides, we found Bombesin (BB) receptor agonists and Pituitary Adenylate Cyclase-Activating Polypeptides (PACAP) to significantly induce insulin secretion and the proteins SerpinA6, STC1, and APOH to significantly stimulate proliferation. ER stress was readily induced by Tunicamycin and resulted in a reduction of insulin mRNA. Somatostatin (SST) was found to be expressed by 1% of the cells and manipulation of the SST receptors was found to significantly affect insulin secretion. Overall, the EndoC-βH1 cells strongly resemble human islet beta cells in terms of glucose and incretin stimulated insulin secretion capabilities. The cell line has an active

  20. Pancreatic Cancer-Derived Exosomes Cause Paraneoplastic β-cell Dysfunction.

    Science.gov (United States)

    Javeed, Naureen; Sagar, Gunisha; Dutta, Shamit K; Smyrk, Thomas C; Lau, Julie S; Bhattacharya, Santanu; Truty, Mark; Petersen, Gloria M; Kaufman, Randal J; Chari, Suresh T; Mukhopadhyay, Debabrata

    2015-04-01

    Pancreatic cancer frequently causes diabetes. We recently proposed adrenomedullin as a candidate mediator of pancreatic β-cell dysfunction in pancreatic cancer. How pancreatic cancer-derived adrenomedullin reaches β cells remote from the cancer to induce β-cell dysfunction is unknown. We tested a novel hypothesis that pancreatic cancer sheds adrenomedullin-containing exosomes into circulation, which are transported to β cells and impair insulin secretion. We characterized exosomes from conditioned media of pancreatic cancer cell lines (n = 5) and portal/peripheral venous blood of patients with pancreatic cancer (n = 20). Western blot analysis showed the presence of adrenomedullin in pancreatic cancer-exosomes. We determined the effect of adrenomedullin-containing pancreatic cancer exosomes on insulin secretion from INS-1 β cells and human islets, and demonstrated the mechanism of exosome internalization into β cells. We studied the interaction between β-cell adrenomedullin receptors and adrenomedullin present in pancreatic cancer-exosomes. In addition, the effect of adrenomedullin on endoplasmic reticulum (ER) stress response genes and reactive oxygen/nitrogen species generation in β cells was shown. Exosomes were found to be the predominant extracellular vesicles secreted by pancreatic cancer into culture media and patient plasma. Pancreatic cancer-exosomes contained adrenomedullin and CA19-9, readily entered β cells through caveolin-mediated endocytosis or macropinocytosis, and inhibited insulin secretion. Adrenomedullin in pancreatic cancer exosomes interacted with its receptor on β cells. Adrenomedullin receptor blockade abrogated the inhibitory effect of exosomes on insulin secretion. β cells exposed to adrenomedullin or pancreatic cancer exosomes showed upregulation of ER stress genes and increased reactive oxygen/nitrogen species. Pancreatic cancer causes paraneoplastic β-cell dysfunction by shedding adrenomedullin(+)/CA19-9(+) exosomes into

  1. Ghrelin’s Effects on Proinflammatory Cytokine Mediated Apoptosis and Their Impact on β-Cell Functionality

    Directory of Open Access Journals (Sweden)

    Antonia Diaz-Ganete

    2015-01-01

    Full Text Available Ghrelin is a peptidic hormone, which stimulates cell proliferation and inhibits apoptosis in several tissues, including pancreas. In preclinical stage of type 1 diabetes, proinflammatory cytokines generate a destructive environment for β-cells known as insulitis, which results in loss of β-cell mass and impaired insulin secretion, leading to diabetes. Our aim was to demonstrate that ghrelin could preserve β-cell viability, turnover rate, and insulin secretion acting as a counter balance of cytokines. In the present work we reproduced proinflammatory milieu found in insulitis stage by treating murine cell line INS-1E and rat islets with a cytokine cocktail including IL-1β, IFNγ, and TNFα and/or ghrelin. Several proteins involved in survival pathways (ERK 1/2 and Akt/PKB and apoptosis (caspases and Bcl-2 protein family and endoplasmic reticulum stress markers as well as insulin secretion were analyzed. Our results show that ghrelin alone has no remarkable effects on β-cells in basal conditions, but interestingly it activates cell survival pathways, downregulates apoptotic mediators and endoplasmic reticulum stress, and restores insulin secretion in response to glucose when beta-cells are cytokine-exposed. These data suggest a potential role of ghrelin in preventing or slowing down the transition from a preclinical to clinically established diabetes by ameliorating the effects of insulitis on β-cells.

  2. Nuclear orphan receptor TLX affects gene expression, proliferation and cell apoptosis in beta cells

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Xiaoli; Xiong, Xiaokan; Dai, Zhe; Deng, Haohua; Sun, Li; Hu, Xuemei; Zhou, Feng; Xu, Yancheng, E-mail: oxyccc@163.com

    2015-12-04

    Nuclear orphan receptor TLX is an essential regulator of the growth of neural stem cells. However, its exact function in pancreatic islet cells is still unknown. In the present study, gene expression profiling analysis revealed that overexpression of TLX in beta cell line MIN6 causes suppression of 176 genes and upregulation of 49 genes, including a cadre of cell cycle, cell proliferation and cell death control genes, such as Btg2, Ddit3 and Gadd45a. We next examined the effects of TLX overexpression on proliferation, apoptosis and insulin secretion in MIN6 cells. Proliferation analysis using EdU assay showed that overexpression of TLX increased percentage of EdU-positive cells. Cell cycle and apoptosis analysis revealed that overexpression of TLX in MIN6 cells resulted in higher percentage of cells exiting G1 into S-phase, and a 58.8% decrease of cell apoptosis induced by 0.5 mM palmitate. Moreover, TLX overexpression did not cause impairment of insulin secretion. Together, we conclude that TLX is among factors capable of controlling beta cell proliferation and survival, which may serve as a target for the development of novel therapies for diabetes. - Highlights: • TLX overexpression in MIN6 cell causes significant expression changes of 225 genes. • TLX overexpression promotes MIN6 cell proliferation and decreases cell apoptosis. • TLX overexpression does not cause impairment of insulin secretion.

  3. Nuclear orphan receptor TLX affects gene expression, proliferation and cell apoptosis in beta cells

    International Nuclear Information System (INIS)

    Shi, Xiaoli; Xiong, Xiaokan; Dai, Zhe; Deng, Haohua; Sun, Li; Hu, Xuemei; Zhou, Feng; Xu, Yancheng

    2015-01-01

    Nuclear orphan receptor TLX is an essential regulator of the growth of neural stem cells. However, its exact function in pancreatic islet cells is still unknown. In the present study, gene expression profiling analysis revealed that overexpression of TLX in beta cell line MIN6 causes suppression of 176 genes and upregulation of 49 genes, including a cadre of cell cycle, cell proliferation and cell death control genes, such as Btg2, Ddit3 and Gadd45a. We next examined the effects of TLX overexpression on proliferation, apoptosis and insulin secretion in MIN6 cells. Proliferation analysis using EdU assay showed that overexpression of TLX increased percentage of EdU-positive cells. Cell cycle and apoptosis analysis revealed that overexpression of TLX in MIN6 cells resulted in higher percentage of cells exiting G1 into S-phase, and a 58.8% decrease of cell apoptosis induced by 0.5 mM palmitate. Moreover, TLX overexpression did not cause impairment of insulin secretion. Together, we conclude that TLX is among factors capable of controlling beta cell proliferation and survival, which may serve as a target for the development of novel therapies for diabetes. - Highlights: • TLX overexpression in MIN6 cell causes significant expression changes of 225 genes. • TLX overexpression promotes MIN6 cell proliferation and decreases cell apoptosis. • TLX overexpression does not cause impairment of insulin secretion.

  4. High Glucose Aggravates the Detrimental Effects of Pancreatic Stellate Cells on Beta-Cell Function

    Directory of Open Access Journals (Sweden)

    Min Zha

    2014-01-01

    Full Text Available Background and Aims. We here assess the effects of PSCs on β-cell function and apoptosis in vivo and in vitro. Materials and Methods. PSCs were transplanted into Wistar and Goto-Kakizaki (GK rats. Sixteen weeks after transplantation, β-cell function, apoptosis, and islet fibrosis were assessed. In vitro the effects of PSCs conditioned medium (PSCs-CM and/or high concentration of glucose on INS-1 cell function was assessed by measuring insulin secretion, INS-1 cell survival, apoptosis, and endoplasmic reticulum stress (ER stress associated CHOP expression. Results. PSCs transplantation exacerbated the impaired β-cell function in GK rats, but had no significant effects in Wistar rats. In vitro, PSCs-CM caused impaired INS-1 cell viability and insulin secretion and increased apoptosis, which were more pronounced in the presence of high glucose. Conclusion. Our study demonstrates that PSCs induce β-cell failure in vitro and in vivo.

  5. Timing of Ca2+ response in pancreatic beta-cells is related to mitochondrial mass

    DEFF Research Database (Denmark)

    Gustavsson, N; Abedi, G; Larsson-Nyrén, G

    2006-01-01

    timing are disturbed in beta-cells from hyperglycemic mice and one of the causes is likely to be an altered mitochondrial metabolism. Mitochondria play a key role in the control of nutrient-induced insulin secretion. Here, we used confocal microscopy with the fluorescent probe MitoTracker Red CMXRos...

  6. Derivation of Insulin Producing Cells From Human Endometrial Stromal Stem Cells and Use in the Treatment of Murine Diabetes

    OpenAIRE

    Santamaria, Xavier; Massasa, Efi E; Feng, Yuzhe; Wolff, Erin; Taylor, Hugh S

    2011-01-01

    Pancreatic islet cell transplantation is an effective approach to treat type 1 diabetes, however the shortage of cadaveric donors and limitations due to rejection require alternative solutions. Multipotent cells derived from the uterine endometrium have the ability to differentiate into mesodermal and ectodermal cellular lineages, suggesting the existence of mesenchymal stem cells in this tissue. We differentiated human endometrial stromal stem cells (ESSC) into insulin secreting cells using ...

  7. ER Stress and β-Cell Pathogenesis of Type 1 and Type 2 Diabetes and Islet Transplantation

    OpenAIRE

    Kataoka, Hitomi Usui; Noguchi, Hirofumi

    2013-01-01

    Endoplasmic reticulum (ER) stress affects the pathogenesis of diabetes. ER stress plays important roles, both in type 1 and type 2 diabetes, because pancreatic β-cells possess highly developed ER for insulin secretion. This review summarizes the relationship between ER stress and the pathogenesis of type 1 and type 2 diabetes. In addition, the association between islet transplantation and ER stress is discussed.

  8. High heritability and genetic correlation of intravenous glucose- and tolbutamide-induced insulin secretion among non-diabetic family members of type 2 diabetic patients

    DEFF Research Database (Denmark)

    Gjesing, Anette Marianne Prior; Hornbak, Malene; Allin, Kristine H.

    2014-01-01

    ∈±∈SE: 0.49∈±∈0.14) and beta cell responsiveness to glucose (h 2∈±∈SE: 0.66∈±∈0.12). Additionally, strong genetic correlations were found between measures of beta cell response after glucose and tolbutamide stimulation, with correlation coefficients ranging from 0.77 to 0.88. Furthermore, we identified......Aims/hypothesis: The aim of this study was to estimate the heritability of quantitative measures of glucose regulation obtained from a tolbutamide-modified frequently sampled IVGTT (t-FSIGT) and to correlate the heritability of the glucose-stimulated beta cell response to the tolbutamide...... after tolbutamide (DIT), insulin sensitivity (SI), glucose effectiveness (SG) and beta cell responsiveness to glucose were calculated. A polygenic variance component model was used to estimate heritability, genetic correlations and associations. Results: We found high heritabilities for acute insulin...

  9. NADPH oxidase 2-derived reactive oxygen species mediate FFAs-induced dysfunction and apoptosis of β-cells via JNK, p38 MAPK and p53 pathways.

    Directory of Open Access Journals (Sweden)

    Huiping Yuan

    2010-12-01

    Full Text Available Dysfunction of β-cell is one of major characteristics in the pathogenesis of type 2 diabetes. The combination of obesity and type 2 diabetes, characterized as 'diabesity', is associated with elevated plasma free fatty acids (FFAs. Oxidative stress has been implicated in the pathogenesis of FFA-induced β-cell dysfunction. However, molecular mechanisms linking between reactive oxygen species (ROS and FFA-induced β-cell dysfunction and apoptosis are less clear. In the present study, we test the hypothesis that NOX2-derived ROS may play a critical role in dysfunction and apoptosis of β-cells induced by FFA. Our results show that palmitate and oleate (0.5 mmol/L, 48 h induced JNK activation and AKT inhibition which resulted in decreased phosphorylation of FOXO1 following nuclear localization and the nucleocytoplasmic translocation of PDX-1, leading to the reducing of insulin and ultimately dysfunction of pancreatic NIT-1 cells. We also found that palmitate and oleate stimulated apoptosis of NIT-1 cells through p38MAPK, p53 and NF-κB pathway. More interestingly, our data suggest that suppression of NOX2 may restore FFA-induced dysfunction and apoptosis of NIT-1 cells. Our findings provide a new insight of the NOX2 as a potential new therapeutic target for preservation of β-cell mass and function.

  10. Molecular phenotyping of multiple mouse strains under metabolic challenge uncovers a role for Elovl2 in glucose-induced insulin secretion

    Directory of Open Access Journals (Sweden)

    Céline Cruciani-Guglielmacci

    2017-04-01

    Conclusion: Our results suggest a role for Elovl2 in ensuring normal insulin secretory responses to glucose. Moreover, the large comprehensive dataset and integrative network-based approach provides a new resource to dissect the molecular etiology of β cell failure under metabolic stress.

  11. Large-scale studies of the functional K variant of the butyrylcholinesterase gene in relation to Type 2 diabetes and insulin secretion

    DEFF Research Database (Denmark)

    Johansen, A; Nielsen, E-M D; Andersen, G

    2004-01-01

    Polymorphisms of the butyrylcholinesterase gene (BCHE) are reported to associate with Alzheimer's disease and a recent study found a significant association of the BCHE K variant (G1615A/Ala539Thr) with Type 2 diabetes. The objectives of our study were to examine whether the BCHE K variant is ass...... is associated with Type 2 diabetes or estimates of pancreatic beta cell function in large-scale populations of glucose-tolerant Caucasians....

  12. Effects of meals rich in either monounsaturated or saturated fat on lipid concentrations and on insulin secretion and action in subjects with high fasting triglyceride concentrations.

    Science.gov (United States)

    Lopez, Sergio; Bermudez, Beatriz; Ortega, Almudena; Varela, Lourdes M; Pacheco, Yolanda M; Villar, Jose; Abia, Rocio; Muriana, Francisco J G

    2011-03-01

    The nature of dietary fats and fasting concentrations of triglycerides affect postprandial hypertriglyceridemia and glucose homeostasis. The objectives were to examine the effects of meals enriched in monounsaturated fatty acids (MUFAs) or saturated fatty acids (SFAs) on postprandial lipid, glucose, and insulin concentrations and to examine the extent of β cell function and insulin sensitivity in subjects with high fasting triglyceride concentrations. Fourteen men with fasting hypertriglyceridemia and normal glucose tolerance were given meals (≈10 kcal/kg body weight) containing MUFAs, SFAs, or no fat. Blood samples were collected at baseline and hourly over 8 h for analysis. The high-fat meals significantly increased postprandial concentrations of triglycerides, nonesterified fatty acids, and insulin and postprandial indexes of β cell function. However, postprandial indexes of insulin sensitivity decreased significantly. These effects were significantly attenuated with MUFAs relative to SFAs. MUFAs postprandially buffered β cell hyperactivity and insulin intolerance relative to SFAs in subjects with high fasting triglyceride concentrations. These data suggest that, in contrast with SFAs, MUFA-based strategies may provide cardiovascular benefits to persons at risk by limiting lipid and insulin excursions and may contribute to optimal glycemic control after meal challenges.

  13. β-cell dysfunction due to increased ER stress in a stem cell model of Wolfram syndrome.

    Science.gov (United States)

    Shang, Linshan; Hua, Haiqing; Foo, Kylie; Martinez, Hector; Watanabe, Kazuhisa; Zimmer, Matthew; Kahler, David J; Freeby, Matthew; Chung, Wendy; LeDuc, Charles; Goland, Robin; Leibel, Rudolph L; Egli, Dieter

    2014-03-01

    Wolfram syndrome is an autosomal recessive disorder caused by mutations in WFS1 and is characterized by insulin-dependent diabetes mellitus, optic atrophy, and deafness. To investigate the cause of β-cell failure, we used induced pluripotent stem cells to create insulin-producing cells from individuals with Wolfram syndrome. WFS1-deficient β-cells showed increased levels of endoplasmic reticulum (ER) stress molecules and decreased insulin content. Upon exposure to experimental ER stress, Wolfram β-cells showed impaired insulin processing and failed to increase insulin secretion in response to glucose and other secretagogues. Importantly, 4-phenyl butyric acid, a chemical protein folding and trafficking chaperone, restored normal insulin synthesis and the ability to upregulate insulin secretion. These studies show that ER stress plays a central role in β-cell failure in Wolfram syndrome and indicate that chemical chaperones might have therapeutic relevance under conditions of ER stress in Wolfram syndrome and other forms of diabetes.

  14. The Finnish Diabetes Risk Score is associated with insulin resistance but not reduced beta-cell function, by classical and model-based estimates

    NARCIS (Netherlands)

    Brodovicz, K.G.; Dekker, J.M.; Rijkelijkhuizen, J.M.; Rhodes, T.; Mari, A.; Alssema, M.J.; Nijpels, G.; Williams-Herman, D.E.; Girman, C.J.

    2011-01-01

    Aims The Finnish Diabetes Risk Score (FINDRISC) is widely used for risk stratification in Type2 diabetes prevention programmes. Estimates of β-cell function vary widely in people without diabetes and reduced insulin secretion has been described in people at risk for diabetes. The aim of this

  15. β cell membrane remodelling and procoagulant events occur in inflammation-driven insulin impairment: a GLP-1 receptor dependent and independent control.

    Science.gov (United States)

    Gleizes, Céline; Kreutter, Guillaume; Abbas, Malak; Kassem, Mohamad; Constantinescu, Andrei Alexandru; Boisramé-Helms, Julie; Yver, Blandine; Toti, Florence; Kessler, Laurence

    2016-02-01

    Inflammation and hyperglycaemia are associated with a prothrombotic state. Cell-derived microparticles (MPs) are the conveyors of active procoagulant tissue factor (TF) and circulate at high concentration in diabetic patients. Liraglutide, a glucagon-like peptide (GLP)-1 analogue, is known to promote insulin secretion and β-cell preservation. In this in vitro study, we examined the link between insulin impairment, procoagulant activity and plasma membrane remodelling, under inflammatory conditions. Rin-m5f β-cell function, TF activity mediated by MPs and their modulation by 1 μM liraglutide were examined in a cell cross-talk model. Methyl-β-cyclodextrine (MCD), a cholesterol depletor, was used to evaluate the involvement of raft on TF activity, MP shedding and insulin secretion as well as Soluble N-éthylmaleimide-sensitive-factor Attachment protein Receptor (SNARE)-dependent exocytosis. Cytokines induced a two-fold increase in TF activity at MP surface that was counteracted by liraglutide. Microparticles prompted TF activity on the target cells and a two-fold decrease in insulin secretion via protein kinase A (PKA) and p38 signalling, that was also abolished by liraglutide. Large lipid raft clusters were formed in response to cytokines and liraglutide or MCD-treated cells showed similar patterns. Cells pre-treated by saturating concentration of the GLP-1r antagonist exendin (9-39), showed a partial abolishment of the liraglutide-driven insulin secretion and liraglutide-decreased TF activity. Measurement of caspase 3 cleavage and MP shedding confirmed the contribution of GLP-1r-dependent and -independent pathways. Our results confirm an integrative β-cell response to GLP-1 that targets receptor-mediated signalling and membrane remodelling pointing at the coupling of insulin secretion and inflammation-driven procoagulant events. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and

  16. Metabolic surgery for non-obese type 2 diabetes: incretins, adipocytokines, and insulin secretion/resistance changes in a 1-year interventional clinical controlled study.

    Science.gov (United States)

    Geloneze, Bruno; Geloneze, Sylka Rodovalho; Chaim, Elinton; Hirsch, Fernanda Filgueira; Felici, Ana Claudia; Lambert, Giselle; Tambascia, Marcos Antonio; Pareja, José Carlos

    2012-07-01

    To compare duodenal-jejunal bypass (DJB) with standard medical care in nonobese patients with type 2 diabetes and evaluate surgically induced endocrine and metabolic changes. Eighteen patients submitted to a DJB procedure met the following criteria: overweight, diabetes diagnosis less than 15 years, current insulin treatment, residual β-cell function, and absence of autoimmunity. Patients who refused surgical treatment received standard medical care (control group). At baseline, 3, 6, and 12 months after surgery, insulin sensitivity and production of glucagon-like peptide-1 and glucose-insulinotropic polypeptide were assessed during a meal tolerance test. Fasting adipocytokines and dipeptidyl-peptidase-4 concentrations were measured. The mean age of the patients was 50 (5) years, time of diagnosis: 9 (2) years, time of insulin usage: 6 (5) months, fasting glucose: 9.9 (2.5) mmol/dL, and HbA1c (glycosylated hemoglobin) level: 8.9% (1.2%). Duodenal-jejunal bypass group showed greater reductions in fasting glucose (22% vs 6% in control group, P < 0.05) and daily insulin requirement (93% vs 15%, P < 0.01). Twelve patients from DJB group stopped using insulin and showed improvements in insulin sensitivity and β-cell function (P < 0.01), and reductions in glucose-insulinotropic polypeptide levels (P < 0.001), glucagon during the first 30 minutes after meal (P < 0.05), and leptin levels (P < 0.05). Dipeptidyl-peptidase-4 levels increased after surgery (P < 0.01), but glucagon-like peptide-1 levels did not change. Duodenal-jejunal bypass improved insulin sensitivity and β-cell function and reduced glucose-insulinotropic polypeptide, leptin, and glucagon production. Hence, DJB resulted in better glycemic control and reduction in insulin requirement but DJB did not result in remission of diabetes.

  17. β-Cell Replacement Strategies: The Increasing Need for a "β-Cell Dogma".

    Science.gov (United States)

    Vieira, Andhira; Druelle, Noémie; Avolio, Fabio; Napolitano, Tiziana; Navarro-Sanz, Sergi; Silvano, Serena; Collombat, Patrick

    2017-01-01

    Type 1 diabetes is an auto-immune disease resulting in the loss of pancreatic β-cells and, consequently, in chronic hyperglycemia. Insulin supplementation allows diabetic patients to control their glycaemia quite efficiently, but treated patients still display an overall shortened life expectancy and an altered quality of life as compared to their healthy counterparts. In this context and due to the ever increasing number of diabetics, establishing alternative therapies has become a crucial research goal. Most current efforts therefore aim at generating fully functional insulin-secreting β-like cells using multiple approaches. In this review, we screened the literature published since 2011 and inventoried the selected markers used to characterize insulin-secreting cells generated by in vitro differentiation of stem/precursor cells or by means of in vivo transdifferentiation. By listing these features, we noted important discrepancies when comparing the different approaches for the initial characterization of insulin-producing cells as true β-cells. Considering the recent advances achieved in this field of research, the necessity to establish strict guidelines has become a subject of crucial importance, especially should one contemplate the next step, which is the transplantation of in vitro or ex vivo generated insulin-secreting cells in type 1 diabetic patients.

  18. Preserved glucagon-like peptide-1 responses to oral glucose, but reduced incretin effect, insulin secretion and sensitivity in young Asians with type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Yeow, Toh Peng; Pacini, Giovanni; Tura, Andrea

    2017-01-01

    are scarce. We examined the insulin resistance, β-cell function (BC), glucagon-like peptide (GLP)-1 hormone and incretin effect in Asian YT2DM. RESEARCH DESIGN AND METHODS: This case-control study recruited 25 Asian YT2DM and 15 healthy controls, matched for gender, ethnicity and body mass index. Serum......OBJECTIVE: Youth onset type 2 diabetes mellitus (YT2DM) is a globally rising phenomenon with substantial Asians representation. The understanding of its pathophysiology is derived largely from studies in the obese African-American and Caucasian populations, while studies on incretin effect...... glucose, insulin, C peptide and GLP-1 were sampled during 2-hour oral glucose tolerance tests (OGTTs) and 1-hour intravenous glucose tolerance tests (IVGTTs). Insulin sensitivity was derived from the Quantitative Insulin Sensitivity Check Index (QUICKI), Oral Glucose Insulin Sensitivity Index (OGIS...

  19. Deteriorated glucose metabolism with a high-protein, low-carbohydrate diet in db mice, an animal model of type 2 diabetes, might be caused by insufficient insulin secretion.

    Science.gov (United States)

    Arimura, Emi; Pulong, Wijang Pralampita; Marchianti, Ancah Caesarina Novi; Nakakuma, Miwa; Abe, Masaharu; Ushikai, Miharu; Horiuchi, Masahisa

    2017-02-01

    We previously showed the deleterious effects of increased dietary protein on renal manifestations and glucose metabolism in leptin receptor-deficient (db) mice. Here, we further examined its effects on glucose metabolism, including urinary C-peptide. We also orally administered mixtures corresponding to low- or high-protein diets to diabetic mice. In diet experiments, under pair-feeding (equivalent energy and fat) conditions using a metabolic cage, mice were fed diets with different protein content (L diet: 12 % protein, 71 % carbohydrate, 17 % fat; H diet: 24 % protein, 59 % carbohydrate, 17 % fat) for 15 days. In oral administration experiments, the respective mixtures (L mixture: 12 % proline, 71 % maltose or starch, 17 % linoleic acid; H mixture: 24 % proline, 59 % maltose or starch, 17 % linoleic acid) were supplied to mice. Biochemical parameters related to glucose metabolism were measured. The db-H diet mice showed significantly higher water intake, urinary volume, and glucose levels than db-L diet mice but similar levels of excreted urinary C-peptide. In contrast, control-H diet mice showed significantly higher C-peptide excretion than control-L diet mice. Both types of mice fed H diet excreted high levels of urinary albumin. When maltose mixtures were administered, db-L mixture mice showed significantly higher blood glucose after 30 min than db-H mixture mice. However, db mice administered starch-H mixture showed significantly higher blood glucose 120-300 min post-administration than db-L mixture mice, although both groups exhibited similar insulin levels. High-protein, low-carbohydrate diets deteriorated diabetic conditions and were associated with insufficient insulin secretion in db mice. Our findings may have implications for dietary management of diabetic symptoms in human patients.

  20. Increased CD19+CD24+CD27+ B regulatory cells are associated with insulin resistance in patients with type I Hashimoto's thyroiditis.

    Science.gov (United States)

    Yang, Min; Du, Changji; Wang, Yinping; Liu, Jun

    2017-06-01

    Hashimoto's thyroiditis (HT) is characterized by dysregulated immune responses and is commonly associated with insulin resistance. However, the mechanism of insulin resistance in HT remains to be fully elucidated. The aim of the present study was to investigate the correlation between the percentage of B regulatory lymphocytes (Bregs) and insulin resistance in patients with HT but with normal thyroid function (type I). A total of 59 patients with type I HT and 38 healthy volunteers were enrolled in the study. An oral glucose tolerance test was performed to measure insulin secretion and assess β‑cell functions. Flow cytometry was performed to examine the percentages of lymphocyte populations. The patients with HT exhibited normal fasting and postprandial glucose and fasting insulin secretion, but increased secretion of early‑phase and total insulin. The patients with HT also had insufficient β‑cell compensation for insulin resistance, indicated by a reduced disposition index, in the fasting state. An elevation in the percentage of CD19+CD24+CD27+ Bregs was also observed, which correlated positively with insulin secretion and insulin resistance in the fasting state. The patients with type I HT had postprandial insulin resistance and insufficient β‑cell compensation for fasting insulin resistance. Therefore, the increase in CD19+CD24+CD27+ Bregs was closely associated with fasting insulin secretion. These results provide novel insight into the mechanism of insulin resistance in HT.

  1. Sleep apnoea syndrome and 10-year cardiovascular risk in females with type 2 diabetes: relationship with insulin secretion and insulin resistance.

    Science.gov (United States)

    Hermans, Michel P; Ahn, Sylvie A; Mahadeb, Yovan P; Rousseau, Michel F

    2013-03-01

    Obstructive sleep apnoea syndrome (OSAS) is a risk factor for type 2 diabetes mellitus (T2DM) and promotes cardiovascular events, especially in men. The prevalence of sleep apnoea and its association with microvascular and macrovascular diseases and glycaemic control are poorly documented in T2DM women. A total of 305 T2DM women were sleep apnoea diagnosed through (hetero)anamnesis, Epworth's score, oximetry and polysomnography. Sleep apnoea[+] (n = 25) were compared with sleep apnoea[-] (n = 280) regarding cardiovascular risk factors, glucose homeostasis, micro/macrovascular complications and the United Kingdom Prospective Diabetes Study (UKPDS) 10-year risk. Mean (1 SD) age was 66 (12) years, diabetes duration 15 (9) years, sleep apnoea prevalence 8.2% and metabolic syndrome 86%. There were no differences in age, diabetes duration, education, smoking and blood pressure between groups. Sleep apnoea[+] had significantly higher values of body mass index, waist, relative/absolute fat, conicity, visceral fat (all p Women with sleep apnoea had higher UKPDS risk of CAD: 18 (11)% versus 12 (10)% (p = 0.0136). Prevalent micro/macrovascular complications were not different between groups. Sleep apnoea, a frequent comorbidity of T2DM women, is associated with central fat, atherogenic dyslipidaemia, inflammation, worsening β-cell function, poorer glycaemic control and coronary artery disease risk. Sleep apnoea may increase residual vascular risk for microvascular and macrovascular events in T2DM women. Copyright © 2013 John Wiley & Sons, Ltd.

  2. Age-related mitochondrial DNA depletion and the impact on pancreatic Beta cell function.

    Science.gov (United States)

    Nile, Donna L; Brown, Audrey E; Kumaheri, Meutia A; Blair, Helen R; Heggie, Alison; Miwa, Satomi; Cree, Lynsey M; Payne, Brendan; Chinnery, Patrick F; Brown, Louise; Gunn, David A; Walker, Mark

    2014-01-01

    Type 2 diabetes is characterised by an age-related decline in insulin secretion. We previously identified a 50% age-related decline in mitochondrial DNA (mtDNA) copy number in isolated human islets. The purpose of this study was to mimic this degree of mtDNA depletion in MIN6 cells to determine whether there is a direct impact on insulin secretion. Transcriptional silencing of mitochondrial transcription factor A, TFAM, decreased mtDNA levels by 40% in MIN6 cells. This level of mtDNA depletion significantly decreased mtDNA gene transcription and translation, resulting in reduced mitochondrial respiratory capacity and ATP production. Glucose-stimulated insulin secretion was impaired following partial mtDNA depletion, but was normalised following treatment with glibenclamide. This confirms that the deficit in the insulin secretory pathway precedes K+ channel closure, indicating that the impact of mtDNA depletion is at the level of mitochondrial respiration. In conclusion, partial mtDNA depletion to a degree comparable to that seen in aged human islets impaired mitochondrial function and directly decreased insulin secretion. Using our model of partial mtDNA depletion following targeted gene silencing of TFAM, we have managed to mimic the degree of mtDNA depletion observed in aged human islets, and have shown how this correlates with impaired insulin secretion. We therefore predict that the age-related mtDNA depletion in human islets is not simply a biomarker of the aging process, but will contribute to the age-related risk of type 2 diabetes.

  3. The Noncaloric Sweetener Rebaudioside A Stimulates Glucagon-Like Peptide 1 Release and Increases Enteroendocrine Cell Numbers in 2-Dimensional Mouse Organoids Derived from Different Locations of the Intestine

    NARCIS (Netherlands)

    van der Wielen, Nikkie; Ten Klooster, Jean Paul; Muckenschnabl, Susanne; Pieters, Raymond; Hendriks, Henk Fj; Witkamp, Renger F; Meijerink, Jocelijn

    2016-01-01

    BACKGROUND: Glucagon-like peptide 1 (GLP-1) contributes to satiety and plays a pivotal role in insulin secretion and glucose homeostasis. Similar to GLP-1, peptide YY (PYY) and cholecystokinin also influence food intake. The secretion of these hormones by enteroendocrine cells along the intestine is

  4. The noncaloric sweetener rebaudioside a stimulates glucagon-like peptide 1 release and increases enteroendocrine cell numbers in 2-dimensional mouse organoids derived from different locations of the intestine

    NARCIS (Netherlands)

    Wielen, van der Nikkie; Klooster, ten Jean Paul; Muckenschnabl, Susanne; Pieters, Raymond; Hendriks, Henk F.J.; Witkamp, Renger F.; Meijerink, Jocelijn

    2016-01-01

    Background: Glucagon-like peptide 1 (GLP-1) contributes to satiety and plays a pivotal role in insulin secretion and glucose homeostasis. Similar to GLP-1, peptide YY (PYY) and cholecystokinin also influence food intake. The secretion of these hormones by enteroendocrine cells along the intestine

  5. FoxO1 Plays an Important Role in Regulating ?-Cell Compensation for Insulin Resistance in Male Mice

    OpenAIRE

    Zhang, Ting; Kim, Dae Hyun; Xiao, Xiangwei; Lee, Sojin; Gong, Zhenwei; Muzumdar, Radhika; Calabuig-Navarro, Virtu; Yamauchi, Jun; Harashima, Hideyoshi; Wang, Rennian; Bottino, Rita; Alvarez-Perez, Juan Carlos; Garcia-Oca?a, Adolfo; Gittes, George; Dong, H. Henry

    2016-01-01

    ?-Cell compensation is an essential mechanism by which ?-cells increase insulin secretion for overcoming insulin resistance to maintain euglycemia in obesity. Failure of ?-cells to compensate for insulin resistance contributes to insulin insufficiency and overt diabetes. To understand the mechanism of ?-cell compensation, we characterized the role of forkhead box O1 (FoxO1) in ?-cell compensation in mice under physiological and pathological conditions. FoxO1 is a key transcription factor that...

  6. The insulinotropic effect of endothelin-1 is mediated by glucagon release from the islet alpha cells

    DEFF Research Database (Denmark)

    Brock, B; Gregersen, S; Kristensen, K

    1999-01-01

    AIMS/HYPOTHESIS: The circulating concentrations of endothelin-1 (ET-1), a peptide derived from endothelium, are increased in hypertension and diabetes. Endothelin-1 has recently been shown to be an insulinotropic agent. The mechanism of action of endothelin-1 on the endocrine pancreas has not yet...... been clarified. METHODS: We investigated the action of endothelin-1 on the insulin secretion, the binding of (125)I-ET-1 to beta cells as well as its effects on purified beta and non-beta cells from normal rats. The expression of endothelin receptors in alpha- and beta-cell lines and in normal rat...... from purified beta cells. Endothelin-1-(100 nmol/l) increased, however, both insulin and glucagon secretion from a mixture of purified beta and non-beta cells indicating that alpha cells seem to have a key role for the action of ET-1 on insulin secretion. CONCLUSION/INTERPRETATION: The insulinotropic...

  7. Increase in homeostasis model assessment of insulin resistance (HOMA-IR) had a strong impact on the development of type 2 diabetes in Japanese individuals with impaired insulin secretion: the Saku study.

    Science.gov (United States)

    Morimoto, Akiko; Tatsumi, Yukako; Soyano, Fumie; Miyamatsu, Naomi; Sonoda, Nao; Godai, Kayo; Ohno, Yuko; Noda, Mitsuhiko; Deura, Kijyo

    2014-01-01

    Our aim was to assess the impact of increase in homeostasis model assessment of insulin resistance (HOMA-IR) on the development of type 2 diabetes in Japanese individuals with impaired insulin secretion (IIS). This study included 2,209 participants aged 30-69 without diabetes at baseline who underwent comprehensive medical check-ups between April 2006 and March 2007 at Saku Central Hospital. Participants were classified into eight groups according to the combination of baseline IIS status (non-IIS and IIS) and category of HOMA-IR change between the baseline and follow-up examinations (decrease, no change/small increase, moderate increase, and large increase). Type 2 diabetes was determined from fasting and 2 h post-load plasma glucose concentrations at the follow-up examination between April 2009 and March 2011. At baseline, 669 individuals (30.3%) were classified as having IIS. At follow-up, 74 individuals developed type 2 diabetes. After adjusting for confounding factors including baseline HOMA-IR values, the multivariable-adjusted odds ratios (95% confidence intervals) for type 2 diabetes in the non-IIS with a decrease (mean change in HOMA-IR: -0.47), non-IIS with a moderate increase (mean change in HOMA-IR: 0.28), non-IIS with a large increase (mean change in HOMA-IR: 0.83), IIS with a decrease (mean change in HOMA-IR: -0.36), IIS with no change/small increase (mean change in HOMA-IR: 0.08), IIS with a moderate increase (mean change in HOMA-IR: 0.27), and IIS with a large increase (mean change in HOMA-IR: 0.73) groups, relative to the non-IIS with no change/small increase (mean change in HOMA-IR: 0.08) group were 0.23 (0.04, 1.11), 1.22 (0.26, 5.72), 2.01 (0.70, 6.46), 1.37 (0.32, 4.28), 3.60 (0.83, 15.57), 5.24 (1.34, 20.52), and 7.01 (1.75, 24.18), respectively. Moderate and large increases in HOMA-IR had a strong impact on the development of type 2 diabetes among individuals with IIS in this Japanese population.

  8. A Biophysical Model of Electrical Activity in Human β-Cells.

    OpenAIRE

    Pedersen, Morten Gram

    2010-01-01

    Electrical activity in pancreatic β-cells plays a pivotal role in glucose-stimulated insulin secretion by coupling metabolism to calcium-triggered exocytosis. Mathematical models based on rodent data have helped in understanding the mechanisms underlying the electrophysiological patterns observed in laboratory animals. However, human β-cells differ in several aspects, and in particular in their electrophysiological characteristics, from rodent β-cells. Hence, from a clinical perspective and t...

  9. Glucose acutely reduces cytosolic and mitochondrial H2O2 in rat pancreatic beta-cells.

    Science.gov (United States)

    Deglasse, Jean-Philippe; Roma, Leticia Prates; Pastor-Flores, Daniel; Gilon, Patrick; Dick, Tobias P; Jonas, Jean-Christophe

    2018-05-14

    Whether H2O2 contributes to the glucose-dependent stimulation of insulin secretion by pancreatic β-cells is highly controversial. We used two H2O2-sensitive probes, roGFP2-Orp1 and HyPer with its pH-control SypHer, to test the acute effects of glucose, monomethylsuccinate, leucine with glutamine, and α-ketoisocaproate, on β-cell cytosolic and mitochondrial H2O2 concentrations. We then tested the effects of low H2O2 and menadione concentrations on insulin secretion. RoGFP2-Orp1 was more sensitive than HyPer to H2O2 (response at 2-5 vs. 10µM) and less pH-sensitive. Under control conditions, stimulation with glucose reduced mitochondrial roGFP2-Orp1 oxidation without affecting cytosolic roGFP2-Orp1 and HyPer fluorescence ratios, except for the pH-dependent effects on HyPer. However, stimulation with glucose decreased the oxidation of both cytosolic probes by 15µM exogenous H2O2. The glucose effects were not affected by overexpression of catalase, mitochondrial catalase or superoxide dismutase 1 and 2. They followed the increase in NAD(P)H autofluorescence, were maximal at 5mM glucose in the cytosol and 10mM glucose in the mitochondria, and were partly mimicked by the other nutrients. Exogenous H2O2 (1-15µM) did not affect insulin secretion. By contrast, menadione (1-5µM) did not increase basal insulin secretion but reduced the stimulation of insulin secretion by 20mM glucose. Subcellular changes in β-cell H2O2 levels are better monitored with roGFP2-Orp1 than HyPer/SypHer. Nutrients acutely lower mitochondrial H2O2 levels in β-cells and promote degradation of exogenously supplied H2O2 in both cytosolic and mitochondrial compartments. The glucose-dependent stimulation of insulin secretion occurs independently of a detectable increase in β-cell cytosolic or mitochondrial H2O2 levels.

  10. Microfluidic Approach to Cell Microencapsulation.

    Science.gov (United States)

    Sharma, Varna; Hunckler, Michael; Ramasubramanian, Melur K; Opara, Emmanuel C; Katuri, Kalyan C

    2017-01-01

    Bioartificial pancreas made of insulin-secreting islets cells holds great promise in the treatment of individuals with Type-1 diabetes. Successful islet cell microencapsulation in biopolymers is a key step for providing immunoisolation of transplanted islet cells. Because of the variability in the size and shape of pancreatic islets, one of the main obstacles in their microencapsulation is the inability to consistently control shape, size, and microstructure of the encapsulating biopolymer capsule. In this chapter, we provide a detailed description of a microfluidic approach to islet cell encapsulation in alginate that might address the microencapsulation challenges.

  11. Emerging roles for protein histidine phosphorylation in cellular signal transduction: lessons from the islet ?-cell

    OpenAIRE

    Kowluru, Anjaneyulu

    2008-01-01

    Protein phosphorylation represents one of the key regulatory events in physiological insulin secretion from the islet ?-cell. In this context, several classes of protein kinases (e.g. calcium-, cyclic nucleotide- and phospholipid-dependent protein kinases and tyrosine kinases) have been characterized in the ?-cell. The majority of phosphorylated amino acids identified include phosphoserine, phosphothreonine and phosphotyrosine. Protein histidine phosphorylation has been implicated in the prok...

  12. The Various Forms of Insulin Secretion Response to the Intravenous and Oral Administration of Glucose in Non-Insulin-Dependent Diabetes Mellitus; Les Differentes Modalites de Reponse Insulino-Secretrice Lors de Charges Veineuse et Orale en Glucose dans le Diabete Sucre Non Insulino-Dependant

    Energy Technology Data Exchange (ETDEWEB)

    Mirouze, J.; Orsetti, A.; Lapinski, H. [Clinique des Maladies Metaboliques et Endocriniennes, Hopital St-Eloi, Montpellier (France)

    1970-02-15

    On the basis of 68 observations on advanced diabetes mellitus (20 cases), latent diabetes with obesity (12 cases), chemical diabetes with subjective symptoms (26 cases) and 10 observations of obesity without diabetes, the authors have analysed the various forms of insulin secretion response to the intravenous and oral administration of glucose. The response appeared to be totally withdrawn in advanced diabetes mellitus although the patients were still capable of responding to stimulation with glucagon. In the two other forms of diabetes described, the response to stimulation by intravenous administration was less marked than in normal subjects. With oral administration, on the other hand, the response was greater, although the insulin secreted in this case appeared ineffective in cases of obesity but effective in conditions without obesity due to the hypoglycaemic effect. (author) [French] A l'aide de 68 observations de diabete sucre evolue (20 cas), latent avec obesite (12 cas), chimique avec malaises (26 cas) et de 10 observations d'obesite sans diabete, les auteurs analysent les differentes modalites de riposte insulino- secretrice lors des charges en glucose, veineuse et orale. La riposte s'avere totalement effondree dans le diabete evolue, mais susceptible de repondre encore a la stimulation par le glucagon. Dans les deux autres formes de diabete decrites, la stimulation par charge veineuse est reduite par rapport au sujet normal alors qu'elle est majoree apres charge orale mais l'insuline ainsi secretee parait inefficace dans l'obesite et efficace puisque hypoglycemiante lors de malaises sans obesite. (author)

  13. A microwell cell culture platform for the aggregation of pancreatic β-cells.

    Science.gov (United States)

    Bernard, Abigail B; Lin, Chien-Chi; Anseth, Kristi S

    2012-08-01

    Cell-cell contact between pancreatic β-cells is important for maintaining survival and normal insulin secretion. Various techniques have been developed to promote cell-cell contact between β-cells, but a simple yet robust method that affords precise control over three-dimensional (3D) β-cell cluster size has not been demonstrated. To address this need, we developed a poly(ethylene glycol) (PEG) hydrogel microwell platform using photolithography. This microwell cell-culture platform promotes the formation of 3D β-cell aggregates of defined sizes from 25 to 210 μm in diameter. Using this platform, mouse insulinoma 6 (MIN6) β-cells formed aggregates with cell-cell adherin junctions. These naturally formed cell aggregates with controllable sizes can be removed from the microwells for macroencapsulation, implantation, or other biological assays. When removed and subsequently encapsulated in PEG hydrogels, the aggregated cell clusters demonstrated improved cellular viability (>90%) over 7 days in culture, while the β-cells encapsulated as single cells maintained only 20% viability. Aggregated MIN6 cells also exhibited more than fourfold higher insulin secretion in response to a glucose challenge compared with encapsulated single β-cells. Further, the cell aggregates stained positively for E-cadherin, indicative of the formation of cell junctions. Using this hydrogel microwell cell-culture method, viable and functional β-cell aggregates of specific sizes were created, providing a platform from which other biologically relevant questions may be answered.

  14. Bisphenol A Is More Potent than Phthalate Metabolites in Reducing Pancreatic β-Cell Function

    Directory of Open Access Journals (Sweden)

    Nina Mickelson Weldingh

    2017-01-01

    Full Text Available Bisphenol A (BPA and phthalates are common environmental contaminants that have been proposed to influence incidence and development of types 1 and 2 diabetes. Thus, effects of BPA and three phthalate metabolites (monoisobutyl phthalate (MiBP, mono-n-butyl phthalate (MnBP, and mono-(2-ethylhexyl phthalate (MEHP were studied in the pancreatic β-cell line INS-1E, after 2–72 h of exposure to 5–500 μM. Three endpoints relevant to accelerated development of types 1 or 2 diabetes were investigated: β-cell viability, glucose-induced insulin secretion, and β-cell susceptibility to cytokine-induced cell death. BPA and the phthalate metabolites reduced cellular viability after 72 h of exposure, with BPA as the most potent chemical. Moreover, BPA, MEHP, and MnBP increased insulin secretion after 2 h of simultaneous exposure to chemicals and glucose, with potency BPA > MEHP > MnBP. Longer chemical exposures (24–72 h showed no consistent effects on glucose-induced insulin secretion, and none of the environmental chemicals affected susceptibility to cytokine-induced cell death. Overall, BPA was more potent than the investigated phthalate metabolites in affecting insulin secretion and viability in the INS-1E pancreatic β-cells. In contrast to recent literature, concentrations with relevance to human exposures (1–500 nM did not affect the investigated endpoints, suggesting that this experimental model displayed relatively low sensitivity to environmental chemical exposure.

  15. Potential differentiation of islet-like cells from pregnant cow-derived placental stem cells.

    Science.gov (United States)

    Peng, Shao-Yu; Chou, Chien-Wen; Kuo, Yu-Hsuan; Shen, Perng-Chih; Shaw, S W Steven

    2017-06-01

    Type 1 diabetes is an autoimmune disease that destroys islet cells and results in insufficient insulin secretion by pancreatic β-cells. Islet transplantation from donors is an approach used for treating patients with diabetes; however, this therapy is difficult to implement because of the lack of donors. Nevertheless, several stem cells have the potential to differentiate from islet-like cells and enable insulin secretion for treating diabetes in animal models. For example, placenta is considered a waste material and can be harvested noninvasively during delivery without ethical or moral concerns. To date, the differentiation of islet-like cells from cow-derived placental stem cells (CPSCs) has yet to be demonstrated. The investigation of potential differentiation of islet-like cells from CPSCs was conducted by supplementation with nicotinamide, exendin-4, glucose, and poly-d-lysine and was detected through reverse transcription polymerase chain reaction, dithizone staining, and immunocytochemical methods. Our results indicated that CPSCs are established and express mesenchymal stem cell surface antigen markers, such as CD73, CD166, β-integrin, and Oct-4, but not hematopoietic stem cell surface antigen markers, such as CD45. After induction, the CPSCs successfully differentiated into islet-like cells. The CPSC-derived islet-like cells expressed islet cell development-related genes, such as insulin, glucagon, pax-4, Nkx6.1, pax-6, and Fox. Moreover, CPSC-derived islet-like cells can be stained with zinc ions, which are widely distributed in the islet cells and enable insulin secretion. Altogether, islet-like cells have the potential to be differentiated from CPSCs without gene manipulation, and can be used in diabetic animal models in the future for preclinical and drug testing trial investigations. Copyright © 2017. Published by Elsevier B.V.

  16. Positive association of free triiodothyronine with pancreatic β-cell function in people with prediabetes.

    Science.gov (United States)

    Oda, T; Taneichi, H; Takahashi, K; Togashi, H; Hangai, M; Nakagawa, R; Ono, M; Matsui, M; Sasai, T; Nagasawa, K; Honma, H; Kajiwara, T; Takahashi, Y; Takebe, N; Ishigaki, Y; Satoh, J

    2015-02-01

    To analyse the effects of thyroid hormones on β-cell function and glucose metabolism in people with prediabetes who are euthyroid. A total of 111 people who were euthyroid underwent 75-g oral glucose tolerance tests, of whom 52 were assigned to the normal glucose tolerance and 59 to the prediabetes groups. Homeostatic model assessment of β-cell function, insulinogenic index and areas under the curve for insulin and glucose were evaluated as indices of pancreatic β-cell function. In both groups, BMI, fasting insulin, homeostasis model assessment ratio and HDL cholesterol correlated significantly with all indices of pancreatic β-cell function. Free triiodothyronine correlated positively with all insulin secretion indices in the prediabetes group. Multiple linear regression analysis showed that free triiodothyronine was an independent variable that had a positive correlation with all indices of β-cell function in the prediabetes group. By contrast, no such correlation was found in the normal glucose tolerance group. Free triiodothyronine is associated with both basal and glucose-stimulated insulin secretion in people with prediabetes who are euthyroid; therefore, the regulation of insulin secretion by thyroid hormones is a potentially novel therapeutic target for the treatment of diabetes. © 2014 The Authors. Diabetic Medicine © 2014 Diabetes UK.

  17. Impact of Perturbed Pancreatic β-Cell Cholesterol Homeostasis on Adipose Tissue and Skeletal Muscle Metabolism

    Science.gov (United States)

    Cochran, Blake J.; Hou, Liming; Manavalan, Anil Paul Chirackal; Moore, Benjamin M.; Tabet, Fatiha; Sultana, Afroza; Cuesta Torres, Luisa; Tang, Shudi; Shrestha, Sudichhya; Senanayake, Praween; Patel, Mili; Ryder, William J.; Bongers, Andre; Maraninchi, Marie; Wasinger, Valerie C.; Westerterp, Marit; Tall, Alan R.; Barter, Philip J.

    2016-01-01

    Elevated pancreatic β-cell cholesterol levels impair insulin secretion and reduce plasma insulin levels. This study establishes that low plasma insulin levels have a detrimental effect on two major insulin target tissues: adipose tissue and skeletal muscle. Mice with increased β-cell cholesterol levels were generated by conditional deletion of the ATP-binding cassette transporters, ABCA1 and ABCG1, in β-cells (β-DKO mice). Insulin secretion was impaired in these mice under basal and high-glucose conditions, and glucose disposal was shifted from skeletal muscle to adipose tissue. The β-DKO mice also had increased body fat and adipose tissue macrophage content, elevated plasma interleukin-6 and MCP-1 levels, and decreased skeletal muscle mass. They were not, however, insulin resistant. The adipose tissue expansion and reduced skeletal muscle mass, but not the systemic inflammation or increased adipose tissue macrophage content, were reversed when plasma insulin levels were normalized by insulin supplementation. These studies identify a mechanism by which perturbation of β-cell cholesterol homeostasis and impaired insulin secretion increase adiposity, reduce skeletal muscle mass, and cause systemic inflammation. They further identify β-cell dysfunction as a potential therapeutic target in people at increased risk of developing type 2 diabetes. PMID:27702832

  18. Characterization of GLP-1 effects on beta-cell function after meal ingestion in humans

    DEFF Research Database (Denmark)

    Ahrén, Bo; Holst, Jens Juul; Mari, Andrea

    2003-01-01

    OBJECTIVE: Glucagon-like peptide 1 (GLP-1) is an incretin that augments insulin secretion after meal intake and is developed for treatment of type 2 diabetes. As a novel therapeutic agent, characteristics of its beta-cell effects are important to establish. Previously, beta-cell effects of GLP-1...... have been characterized in humans during graded intravenous infusions of glucose, whereas its effects after more physiological stimuli, like meal intake, are not known. RESEARCH DESIGN AND METHODS: Eight women (aged 69 years, fasting glucose 3.7-10.3 mmol/l, BMI 22.4-43.9 kg/m(2)) who had fasted...... meal augments insulin secretion in humans by a dose...

  19. Tributyltin exposure at noncytotoxic doses dysregulates pancreatic β-cell function in vitro and in vivo.

    Science.gov (United States)

    Chen, Ya-Wen; Lan, Kuo-Cheng; Tsai, Jing-Ren; Weng, Te-I; Yang, Ching-Yao; Liu, Shing-Hwa

    2017-09-01

    Tributyltin (TBT) is an endocrine disruptor. TBT can be found in food and in human tissues and blood. Several animal studies revealed that organotins induced diabetes with decreased insulin secretion. The detailed effect and mechanism of TBT on pancreatic β-cell function still remain unclear. We investigated the effect and mechanism of TBT exposure at noncytotoxic doses relevant to human exposure on β-cell function in vitro and in vivo. The β-cell-derived RIN-m5F cells and pancreatic islets from mouse and human were treated with TBT (0.05-0.2 μM) for 0.5-4 h. Adult male mice were orally exposed to TBT (25 μg/kg/day) with or without antioxidant N-acetylcysteine (NAC) for 1-3 weeks. Assays for insulin secretion and glucose metabolism were carried out. Unlike previous studies, TBT at noncytotoxic concentrations significantly increased glucose-stimulated insulin secretion and intracellular Ca 2+ ([Ca 2+ ] i ) in β-cells. The reactive oxygen species (ROS) production and phosphorylation of protein kinase C (PKC-pan) and extracellular signal-regulated kinase (ERK)1/2 were also increased. These TBT-triggered effects could be reversed by antiestrogen ICI182780 and inhibitors of ROS, [Ca 2+ ] i , and PKC, but not ERK. Similarly, islets treated with TBT significantly increased glucose-stimulated insulin secretion, which could be reversed by ICI182780, NAC, and PKC inhibitor. Mice exposed to TBT for 3 weeks significantly increased blood glucose and plasma insulin and induced glucose intolerance and insulin resistance, which could be reversed by NAC. These findings suggest that low/noncytotoxic doses of TBT induce insulin dysregulation and disturb glucose homeostasis, which may be mediated through the estrogen receptor-regulated and/or oxidative stress-related signaling pathways.

  20. Overexpression of monocarboxylate transporter-1 (Slc16a1) in mouse pancreatic ß-cells leads to relative hyperinsulinism during exercise

    DEFF Research Database (Denmark)

    Pullen, Timothy J; Sylow, Lykke; Sun, Gao

    2012-01-01

    Exercise-induced hyperinsulinism (EIHI) is an autosomal dominant disorder characterized by inappropriate insulin secretion in response to vigorous physical exercise or pyruvate injection. Activating mutations in the monocarboxylate transporter-1 (MCT1, SLC16A1) promoter have been linked to EIHI....... Expression of this pyruvate transporter is specifically repressed (disallowed) in pancreatic ß-cells, despite nearly universal expression across other tissues. It has been impossible to determine, however, whether EIHI mutations cause MCT1 expression in patient ß-cells. The hypothesis that MCT1 expression...... in ß-cells is sufficient to cause EIHI by allowing entry of pyruvate and triggering insulin secretion thus remains unproven. Therefore, we generated a transgenic mouse capable of doxycycline-induced, ß-cell-specific overexpression of MCT1 to test this model directly. MCT1 expression caused isolated...

  1. Characterisation of insulin-producing cells differentiated from tonsil derived mesenchymal stem cells.

    Science.gov (United States)

    Kim, So-Yeon; Kim, Ye-Ryung; Park, Woo-Jae; Kim, Han Su; Jung, Sung-Chul; Woo, So-Youn; Jo, Inho; Ryu, Kyung-Ha; Park, Joo-Won

    2015-01-01

    Tonsil-derived (T-) mesenchymal stem cells (MSCs) display mutilineage differentiation potential and self-renewal capacity and have potential as a banking source. Diabetes mellitus is a prevalent disease in modern society, and the transplantation of pancreatic progenitor cells or various stem cell-derived insulin-secreting cells has been suggested as a novel therapy for diabetes. The potential of T-MSCs to trans-differentiate into pancreatic progenitor cells or insulin-secreting cells has not yet been investigated. We examined the potential of human T-MSCs to trans-differentiate into pancreatic islet cells using two different methods based on β-mercaptoethanol and insulin-transferin-selenium, respectively. First, we compared the efficacy of the two methods for inducing differentiation into insulin-producing cells. We demonstrated that the insulin-transferin-selenium method is more efficient for inducing differentiation into insulin-secreting cells regardless of the source of the MSCs. Second, we compared the differentiation potential of two different MSC types: T-MSCs and adipose-derived MSCs (A-MSCs). T-MSCs had a differentiation capacity similar to that of A-MSCs and were capable of secreting insulin in response to glucose concentration. Islet-like clusters differentiated from T-MSCs had lower synaptotagmin-3, -5, -7, and -8 levels, and consequently lower secreted insulin levels than cells differentiated from A-MSCs. These results imply that T-MSCs can differentiate into functional pancreatic islet-like cells and could provide a novel, alternative cell therapy for diabetes mellitus. Copyright © 2015 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

  2. Stevioside improves pancreatic beta-cell function during glucotoxicity via regulation of acetyl-CoA carboxylase.

    Science.gov (United States)

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

    2007-06-01

    Chronic hyperglycemia is detrimental to pancreatic beta-cells, causing impaired insulin secretion and beta-cell turnover. The characteristic secretory defects are increased basal insulin secretion (BIS) and a selective loss of glucose-stimulated insulin secretion (GSIS). Several recent studies support the view that the acetyl-CoA carboxylase (ACC) plays a pivotal role for GSIS. We have shown that stevioside (SVS) enhances insulin secretion and ACC gene expression. Whether glucotoxicity influences ACC and whether this action can be counteracted by SVS are not known. To investigate this, we exposed isolated mouse islets as well as clonal INS-1E beta-cells for 48 h to 27 or 16.7 mM glucose, respectively. We found that 48-h exposure to high glucose impairs GSIS from mouse islets and INS-1E cells, an effect that is partly counteracted by SVS. The ACC dephosphorylation inhibitor okadaic acid (OKA, 10(-8) M), and 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR, 10(-4) M), an activator of 5'-AMP protein kinase that phosphorylates ACC, eliminated the beneficial effect of SVS. 5-Tetrade-cyloxy-2-furancarboxylic acid (TOFA), the specific ACC inhibitor, blocked the effect of SVS as well. During glucotoxity, ACC gene expression, ACC protein, and phosphorylated ACC protein were increased in INS-1E beta-cells. SVS pretreatment further increased ACC gene expression with strikingly elevated ACC activity and increased glucose uptake accompanied by enhanced GSIS. Our studies show that glucose is a potent stimulator of ACC and that SVS to some extent counteracts glucotoxicity via increased ACC activity. SVS possesses the potential to alleviate negative effects of glucotoxicity in beta-cells via a unique mechanism of action.

  3. Characterization of stimulus-secretion coupling in the human pancreatic EndoC-βH1 beta cell line.

    Directory of Open Access Journals (Sweden)

    Lotta E Andersson

    Full Text Available Studies on beta cell metabolism are often conducted in rodent beta cell lines due to the lack of stable human beta cell lines. Recently, a human cell line, EndoC-βH1, was generated. Here we investigate stimulus-secretion coupling in this cell line, and compare it with that in the rat beta cell line, INS-1 832/13, and human islets.Cells were exposed to glucose and pyruvate. Insulin secretion and content (radioimmunoassay, gene expression (Gene Chip array, metabolite levels (GC/MS, respiration (Seahorse XF24 Extracellular Flux Analyzer, glucose utilization (radiometric, lactate release (enzymatic colorimetric, ATP levels (enzymatic bioluminescence and plasma membrane potential and cytoplasmic Ca2+ responses (microfluorometry were measured. Metabolite levels, respiration and insulin secretion were examined in human islets.Glucose increased insulin release, glucose utilization, raised ATP production and respiratory rates in both lines, and pyruvate increased insulin secretion and respiration. EndoC-βH1 cells exhibited higher insulin secretion, while plasma membrane depolarization was attenuated, and neither glucose nor pyruvate induced oscillations in intracellular calcium concentration or plasma membrane potential. Metabolite profiling revealed that glycolytic and TCA-cycle intermediate levels increased in response to glucose in both cell lines, but responses were weaker in EndoC-βH1 cells, similar to those observed in human islets. Respiration in EndoC-βH1 cells was more similar to that in human islets than in INS-1 832/13 cells.Functions associated with early stimulus-secretion coupling, with the exception of plasma membrane potential and Ca2+ oscillations, were similar in the two cell lines; insulin secretion, respiration and metabolite responses were similar in EndoC-βH1 cells and human islets. While both cell lines are suitable in vitro models, with the caveat of replicating key findings in isolated islets, EndoC-βH1 cells have the

  4. Efficient generation of functional pancreatic β-cells from human induced pluripotent stem cells.

    Science.gov (United States)

    Yabe, Shigeharu G; Fukuda, Satsuki; Takeda, Fujie; Nashiro, Kiyoko; Shimoda, Masayuki; Okochi, Hitoshi

    2017-02-01

    Insulin-secreting cells have been generated from human embryonic or induced pluripotent stem cells (iPSCs) by mimicking developmental processes. However, these cells do not always secrete glucose-responsive insulin, one of the most important characteristics of pancreatic β-cells. We focused on the importance of endodermal differentiation from human iPSCs in order to obtain functional pancreatic β-cells. A six-stage protocol was established for the differentiation of human iPSCs to pancreatic β-cells using defined culture media without feeders or serum. The effects of CHIR99021, a selective glycogen synthase kinase-3β inhibitor, were examined in the presence of fibroblast growth factor 2, activin, and bone morphogenetic protein 4 (FAB) during definitive endodermal induction by immunostaining for SRY (sex determining region Y)-box 17 (SOX17) and Forkhead box protein A2 (FOXA2). Insulin secretion was compared between the last stage of monolayer culture and spheroid culture conditions. Cultured cells were transplanted under kidney capsules of streptozotocin-diabetic non-obese diabetic-severe combined immunodeficiency mice, and blood glucose levels were measured once a week. Immunohistochemical analyses were performed 4 and 12 weeks after transplantation. Addition of CHIR99021 (3 μmol/L) in the presence of FAB for 2 days improved endodermal cell viability, maintaining the high SOX17-positive rate. Spheroid formation after the endocrine progenitor stage showed more efficient insulin secretion than did monolayer culture. After cell transplantation, diabetic mice had lower blood glucose levels, and islet-like structures were detected in vivo. Functional pancreatic β-cells were generated from human iPSCs. Induction of definitive endoderm and spheroid formation may be key steps for producing these cells. © 2016 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

  5. Central infusion of leptin improves insulin resistance and suppresses beta-cell function, but not beta-cell mass, primarily through the sympathetic nervous system in a type 2 diabetic rat model.

    Science.gov (United States)

    Park, Sunmin; Ahn, Il Sung; Kim, Da Sol

    2010-06-05

    We investigated whether hypothalamic leptin alters beta-cell function and mass directly via the sympathetic nervous system (SNS) or indirectly as the result of altered insulin resistant states. The 90% pancreatectomized male Sprague Dawley rats had sympathectomy into the pancreas by applying phenol into the descending aorta (SNSX) or its sham operation (Sham). Each group was divided into two sections, receiving either leptin at 300ng/kgbw/h or artificial cerebrospinal fluid (aCSF) via intracerebroventricular (ICV) infusion for 3h as a short-term study. After finishing the infusion study, ICV leptin (3mug/kg bw/day) or ICV aCSF (control) was infused in rats fed 30 energy % fat diets by osmotic pump for 4weeks. At the end of the long-term study, glucose-stimulated insulin secretion and islet morphometry were analyzed. Acute ICV leptin administration in Sham rats, but not in SNSX rats, suppressed the first- and second-phase insulin secretion at hyperglycemic clamp by about 48% compared to the control. Regardless of SNSX, the 4-week administration of ICV leptin improved glucose tolerance during oral glucose tolerance tests and insulin sensitivity at hyperglycemic clamp, compared to the control, while it suppressed second-phase insulin secretion in Sham rats but not in SNSX rats. However, the pancreatic beta-cell area and mass were not affected by leptin and SNSX, though ICV leptin decreased individual beta-cell size and concomitantly increased beta-cell apoptosis in Sham rats. Leptin directly decreases insulin secretion capacity mainly through the activation of SNS without modulating pancreatic beta-cell mass.

  6. Mathematical model of the glucose–insulin regulatory system: From the bursting electrical activity in pancreatic β-cells to the glucose dynamics in the whole body

    Energy Technology Data Exchange (ETDEWEB)

    Han, Kyungreem [College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Kang, Hyuk [National Institute for Mathematical Sciences, Daejeon 305-340 (Korea, Republic of); Choi, M.Y., E-mail: mychoi@snu.ac.kr [Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747 (Korea, Republic of); Kim, Jinwoong, E-mail: jwkim@snu.ac.kr [College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, Myung-Shik [Department of Medicine, Samsung Medical Center, and School of Medicine, Sungkyunkwan University, Seoul 135-710 (Korea, Republic of)

    2012-10-01

    A theoretical approach to the glucose–insulin regulatory system is presented. By means of integrated mathematical modeling and extensive numerical simulations, we probe the cell-level dynamics of the membrane potential, intracellular Ca{sup 2+} concentration, and insulin secretion in pancreatic β-cells, together with the whole-body level glucose–insulin dynamics in the liver, brain, muscle, and adipose tissues. In particular, the three oscillatory modes of insulin secretion are reproduced successfully. Such comprehensive mathematical modeling may provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination. -- Highlights: ► We present a mathematical model for the glucose–insulin regulatory system. ► This model combines the microscopic insulin secretion mechanism in a pancreatic β-cell and macroscopic glucose dynamics at the whole-body level. ► This work is expected to provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination.

  7. Mathematical model of the glucose–insulin regulatory system: From the bursting electrical activity in pancreatic β-cells to the glucose dynamics in the whole body

    International Nuclear Information System (INIS)

    Han, Kyungreem; Kang, Hyuk; Choi, M.Y.; Kim, Jinwoong; Lee, Myung-Shik

    2012-01-01

    A theoretical approach to the glucose–insulin regulatory system is presented. By means of integrated mathematical modeling and extensive numerical simulations, we probe the cell-level dynamics of the membrane potential, intracellular Ca 2+ concentration, and insulin secretion in pancreatic β-cells, together with the whole-body level glucose–insulin dynamics in the liver, brain, muscle, and adipose tissues. In particular, the three oscillatory modes of insulin secretion are reproduced successfully. Such comprehensive mathematical modeling may provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination. -- Highlights: ► We present a mathematical model for the glucose–insulin regulatory system. ► This model combines the microscopic insulin secretion mechanism in a pancreatic β-cell and macroscopic glucose dynamics at the whole-body level. ► This work is expected to provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination.

  8. Nuclear orphan receptor TLX affects gene expression, proliferation and cell apoptosis in beta cells.

    Science.gov (United States)

    Shi, Xiaoli; Xiong, Xiaokan; Dai, Zhe; Deng, Haohua; Sun, Li; Hu, Xuemei; Zhou, Feng; Xu, Yancheng

    Nuclear orphan receptor TLX is an essential regulator of the growth of neural stem cells. However, its exact function in pancreatic islet cells is still unknown. In the present study, gene expression profiling analysis revealed that overexpression of TLX in beta cell line MIN6 causes suppression of 176 genes and upregulation of 49 genes, including a cadre of cell cycle, cell proliferation and cell death control genes, such as Btg2, Ddit3 and Gadd45a. We next examined the effects of TLX overexpression on proliferation, apoptosis and insulin secretion in MIN6 cells. Proliferation analysis using EdU assay showed that overexpression of TLX increased percentage of EdU-positive cells. Cell cycle and apoptosis analysis revealed that overexpression of TLX in MIN6 cells resulted in higher percentage of cells exiting G1 into S-phase, and a 58.8% decrease of cell apoptosis induced by 0.5 mM palmitate. Moreover, TLX overexpression did not cause impairment of insulin secretion. Together, we conclude that TLX is among factors capable of controlling beta cell proliferation and survival, which may serve as a target for the development of novel therapies for diabetes. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Imidazoline NNC77-0074 stimulates Ca2+-evoked exocytosis in INS-1E cells by a phospholipase A2-dependent mechanism

    DEFF Research Database (Denmark)

    Olsen, Hervør L; Nørby, Peder L; Høy, Marianne

    2003-01-01

    We have previously demonstrated that the novel imidazoline compound (+)-2-(2-(4,5-dihydro-1H-imidazol-2-yl)-thiopene-2-yl-ethyl)-pyridine (NNC77-0074) increases insulin secretion from pancreatic beta-cells by stimulation of Ca(2+)-dependent exocytosis. Using capacitance measurements, we now show...... that NNC77-0074 stimulates exocytosis in clonal INS-1E cells. NNC77-0074-stimulated exocytosis was antagonised by the cytoplasmic phospholipase A(2) (cPLA(2)) inhibitors ACA and AACOCF(3) and in cells treated with antisense oligonucleotide against cPLA(2)alpha. NNC77-0074-evoked insulin secretion...... was likewise inhibited by ACA, AACOCF(3), and cPLA(2)alpha antisense oligonucleotide treatment. In pancreatic islets NNC77-0074 stimulated PLA(2) activity. We propose that cPLA(2)alpha plays an important role in the regulation of NNC77-0074-evoked exocytosis in insulin secreting beta-cells....

  10. Resveratrol Ameliorates the Maturation Process of β-Cell-Like Cells Obtained from an Optimized Differentiation Protocol of Human Embryonic Stem Cells

    Science.gov (United States)

    Pezzolla, Daniela; López-Beas, Javier; Lachaud, Christian C.; Domínguez-Rodríguez, Alejandro; Smani, Tarik; Hmadcha, Abdelkrim; Soria, Bernat

    2015-01-01

    Human embryonic stem cells (hESCs) retain the extraordinary capacity to differentiate into different cell types of an adult organism, including pancreatic β-cells. For this particular lineage, although a lot of effort has been made in the last ten years to achieve an efficient and reproducible differentiation protocol, it was not until recently that this aim was roughly accomplished. Besides, several studies evidenced the impact of resveratrol (RSV) on insulin secretion, even though the mechanism by which this polyphenol potentiates glucose-stimulated insulin secretion (GSIS) is still not clear. The aim of this study was to optimize an efficient differentiation protocol that mimics in vivo pancreatic organogenesis and to investigate whether RSV may improve the final maturation step to obtain functional insulin-secreting cells. Our results indicate that treatment of hESCs (HS-181) with activin-A induced definitive endoderm differentiation as detected by the expression of SOX17 and FOXA2. Addition of retinoic acid (RA), Noggin and Cyclopamine promoted pancreatic differentiation as indicated by the expression of the early pancreatic progenitor markers ISL1, NGN3 and PDX1. Moreover, during maturation in suspension culture, differentiating cells assembled in islet-like clusters, which expressed specific endocrine markers such as PDX1, SST, GCG and INS. Similar results were confirmed with the human induced Pluripotent Stem Cell (hiPSC) line MSUH-001. Finally, differentiation protocols incorporating RSV treatment yielded numerous insulin-positive cells, induced significantly higher PDX1 expression and were able to transiently normalize glycaemia when transplanted in streptozotocin (STZ) induced diabetic mice thus promoting its survival. In conclusion, our strategy allows the efficient differentiation of hESCs into pancreatic endoderm capable of generating β-cell-like cells and demonstrates that RSV improves the maturation process. PMID:25774684

  11. Stem Cell Treatment for Type 1 Diabetes

    Directory of Open Access Journals (Sweden)

    Ming eLi

    2014-03-01

    Full Text Available Type 1 diabetes mellitus (T1DM is a common chronic disease in children, characterized by a loss of  cells, which results in defects in insulin secretion and hyperglycemia. Chronic hyperglycemia causes diabetic complications, including diabetic nephropathy, neuropathy and retinopathy. Curative therapies mainly include diet and insulin administration. Although hyperglycemia can be improved by insulin administration, exogenous insulin injection cannot successfully mimic the insulin secretion from normal  cells, which keeps blood glucose levels within the normal range all the time. Islet and pancreas transplantation achieves better glucose control, but there is a lack of organ donors. Cell based therapies have also been attempted to treat T1DM. Stem cells such as embryonic stem cells, induced pluripotent stem cells and tissue stem cells (TSCs such as bone marrow-, adipose tissue- and cord blood-derived stem cells, have been shown to generate insulin-producing cells. In this review, we summarize the most-recently available information about T1DM and the use of TSCs to treat T1DM.

  12. LH-21 and abnormal cannabidiol improve β-cell function in isolated human and mouse islets through GPR55-dependent and -independent signalling.

    Science.gov (United States)

    Ruz-Maldonado, Inmaculada; Pingitore, Attilio; Liu, Bo; Atanes, Patricio; Huang, Guo Cai; Baker, David; Alonso, Francisco José; Bermúdez-Silva, Francisco Javier; Persaud, Shanta J

    2018-04-01

    To examine the effects of Abn-CBD (GPR55 agonist) and LH-21 (CB1 antagonist) on human and mouse islet function, and to determine signalling via GPR55 using islets from GPR55 -/- mice. Islets isolated from human organ donors and mice were incubated in the absence or presence of Abn-CBD or LH-21, and insulin secretion, [Ca 2+ ] i, cAMP , apoptosis, β-cell proliferation and CREB and AKT phosphorylation were examined using standard techniques. Abn-CBD potentiated glucose-stimulated insulin secretion and elevated [Ca 2+ ] i in human islets and islets from both GPR55 +/+ and GPR55 -/- mice. LH-21 also increased insulin secretion and [Ca 2+ ] i in human islets and GPR55 +/+ mouse islets, but concentrations of LH-21 up to 0.1 μM were ineffective in islets from GPR55 -/- mice. Neither ligand affected basal insulin secretion or islet cAMP levels. Abn-CBD and LH-21 reduced cytokine-induced apoptosis in human islets and GPR55 +/+ mouse islets, and these effects were suppressed after GPR55 deletion. They also increased β-cell proliferation: the effects of Abn-CBD were preserved in islets from GPR55 -/- mice, while those of LH-21 were abolished. Abn-CBD and LH-21 increased AKT phosphorylation in mouse and human islets. This study showed that Abn-CBD and LH-21 improve human and mouse islet β-cell function and viability. Use of islets from GPR55 -/- mice suggests that designation of Abn-CBD and LH-21 as a GPR55 agonist and a CB1 antagonist, should be revised. © 2017 John Wiley & Sons Ltd.

  13. Study of insulin resistance and insulin secretion function in overweight and obese subjects with endothelial dysfunction%肥胖伴内皮功能异常者胰岛抵抗与胰岛β细胞功能状况的研究

    Institute of Scientific and Technical Information of China (English)

    朱旅云; 刘坤申

    2004-01-01

    Objective: To investigate the impacts of endothelial dysfunction on insulin resistance (IR) and insulin secretion function in overweight and obese subjects. Methods: 296 overweight and obese subjects were divided into impaired and normal endothelial function (A and B group, respectively). 87 normal weight and healthy subjects without endothelial dysfunction acted as normal control ( C group). The body mass index (BMI), waist circumference (W), waist-hip ratio (WHR), SBP, DBP, fasting blood glucose (FBG), and insulin (FINS), postprandial 2h blood glucose (PBG) and insulin (PINS), lipid profile, creatnine (Cr) and uric acid (Ur) were measured. Homeostasis model assessment (HOMA) was applied to calculate HOMA - IR as an index of IR and HOMA - β as an index of beta - cell function. Results: BMI, W, WHR, SBP, DBP, TG and Ur in both A and B groups were higher than in C group (P<0.05 ~0.001), and compared with Group B, W, WHR, DBP, TG and Ur in group A were significantly increased (P<0.05 ~0.01 ), FBG, FINS, HOMA - IR and GOMA - β in group A were significantly higher than in Group B was similar to Group C in HOMA - β. The flow - mediated endothelium - dependent dilation in Group A was significantly higher than that in Group B (P <0.05 ~ 0.001 ). Group B was similar to Group C in HOMA - β. The flow - mediated endothelium - dependent dilatation in Group A was significantly lower than th at inlatter two groups. The flow - mediated dilatation was closely negatively correlated with HOMA - IR and HOMA - β (γ= -0. 197, P <0.05 andγ= -0. 136, P <0.01 ) but there were no significant correlation in B and C groups. Conclusion: Endothelial dysfunction is an important risk factor affecting the clustering of cardiovascular risk factors, the occurring and developing of IR in overweight and obese subjects.%目的探讨内皮功能障碍对肥胖者胰岛素抵抗(IR)及胰岛β细胞功能的影响.方法296例单纯肥胖者被分为内皮功能异常组(A组)与

  14. Replication confers β cell immaturity.

    Science.gov (United States)

    Puri, Sapna; Roy, Nilotpal; Russ, Holger A; Leonhardt, Laura; French, Esra K; Roy, Ritu; Bengtsson, Henrik; Scott, Donald K; Stewart, Andrew F; Hebrok, Matthias

    2018-02-02

    Pancreatic β cells are highly specialized to regulate systemic glucose levels by secreting insulin. In adults, increase in β-cell mass is limited due to brakes on cell replication. In contrast, proliferation is robust in neonatal β cells that are functionally immature as defined by a lower set point for glucose-stimulated insulin secretion. Here we show that β-cell proliferation and immaturity are linked by tuning expression of physiologically relevant, non-oncogenic levels of c-Myc. Adult β cells induced to replicate adopt gene expression and metabolic profiles resembling those of immature neonatal β that proliferate readily. We directly demonstrate that priming insulin-producing cells to enter the cell cycle promotes a functionally immature phenotype. We suggest that there exists a balance between mature functionality and the ability to expand, as the phenotypic state of the β cell reverts to a less functional one in response to proliferative cues.

  15. Magnetic resonance imaging of mouse islet grafts labeled with novel chitosan-coated superparamagnetic iron oxide nanoparticles.

    Directory of Open Access Journals (Sweden)

    Jyuhn-Huarng Juang

    Full Text Available To better understand the fate of islet isografts and allografts, we utilized a magnetic resonance (MR imaging technique to monitor mouse islets labeled with a novel MR contrast agent, chitosan-coated superparamagnetic iron oxide (CSPIO nanoparticles.After being incubated with and without CSPIO (10 µg/ml, C57BL/6 mouse islets were examined under transmission electron microscope (TEM and their insulin secretion was measured. Cytotoxicity was examined in α (αTC1 and β (NIT-1 and βTC cell lines as well as islets. C57BL/6 mice were used as donors and inbred C57BL/6 and Balb/c mice were used as recipients of islet transplantation. Three hundred islets were transplanted under the left kidney capsule of each mouse and then MR was performed in the recipients periodically. At the end of study, the islet graft was removed for histology and TEM studies.After incubation of mouse islets with CSPIO (10 µg/mL, TEM showed CSPIO in endocytotic vesicles of α- and β-cells at 8 h. Incubation with CSPIO did not affect insulin secretion from islets and death rates of αTC1, NIT-1 and βTC cell lines as well as islets. After syngeneic and allogeneic transplantation, grafts of CSPIO-labeled islets were visualized on MR scans as persistent hypointense areas. At 8 weeks after syngeneic transplantation and 31 days after allogeneic transplantation, histology of CSPIO-labeled islet grafts showed colocalized insulin and iron staining in the same areas but the size of allografts decreased with time. TEM with elementary iron mapping demonstrated CSPIO distributed in the cytoplasm of islet cells, which maintained intact ultrastructure.Our results indicate that after syngeneic and allogeneic transplantation, islets labeled with CSPIO nanoparticles can be effectively and safely imaged by MR.

  16. Elevated Medium-Chain Acylcarnitines Are Associated With Gestational Diabetes Mellitus and Early Progression to Type 2 Diabetes and Induce Pancreatic β-Cell Dysfunction.

    Science.gov (United States)

    Batchuluun, Battsetseg; Al Rijjal, Dana; Prentice, Kacey J; Eversley, Judith A; Burdett, Elena; Mohan, Haneesha; Bhattacharjee, Alpana; Gunderson, Erica P; Liu, Ying; Wheeler, Michael B

    2018-05-01

    Specific circulating metabolites have emerged as important risk factors for the development of diabetes. The acylcarnitines (acylCs) are a family of metabolites known to be elevated in type 2 diabetes (T2D) and linked to peripheral insulin resistance. However, the effect of acylCs on pancreatic β-cell function is not well understood. Here, we profiled circulating acylCs in two diabetes cohorts: 1 ) women with gestational diabetes mellitus (GDM) and 2 ) women with recent GDM who later developed impaired glucose tolerance (IGT), new-onset T2D, or returned to normoglycemia within a 2-year follow-up period. We observed a specific elevation in serum medium-chain (M)-acylCs, particularly hexanoyl- and octanoylcarnitine, among women with GDM and individuals with T2D without alteration in long-chain acylCs. Mice treated with M-acylCs exhibited glucose intolerance, attributed to impaired insulin secretion. Murine and human islets exposed to elevated levels of M-acylCs developed defects in glucose-stimulated insulin secretion and this was directly linked to reduced mitochondrial respiratory capacity and subsequent ability to couple glucose metabolism to insulin secretion. In conclusion, our study reveals that an elevation in circulating M-acylCs is associated with GDM and early stages of T2D onset and that this elevation directly impairs β-cell function. © 2018 by the American Diabetes Association.

  17. Can CD44 Be a Mediator of Cell Destruction? The Challenge of Type 1 Diabetes

    Science.gov (United States)

    Assayag-Asherie, Nathalie; Sever, Dror; Bogdani, Marika; Johnson, Pamela; Weiss, Talya; Ginzberg, Ariel; Perles, Sharon; Weiss, Lola; Sebban, Lora Eshkar; Turley, Eva A.; Okon, Elimelech; Raz, Itamar; Naor, David

    2015-01-01

    CD44 is a multi-functional receptor with multiple of isoforms engaged in modulation of cell trafficking and transmission of apoptotic signals. We have previously shown that injection of anti-CD44 antibody into NOD mice induced resistance to type 1 diabetes (T1D). In this communication we describe our efforts to understand the mechanism underlying this effect. We found that CD44-deficient NOD mice develop stronger resistance to T1D than wild-type littermates. This effect is not explained by the involvement of CD44 in cell migration, because CD44-deficient inflammatory cells surprisingly had greater invasive potential than the corresponding wild type cells, probably owing to molecular redundancy. We have previously reported and we show here again that CD44 expression and hyaluronic acid (HA, the principal ligand for CD44) accumulation are detected in pancreatic islets of diabetic NOD mice, but not of non-diabetic DBA/1 mice. Expression of CD44 on insulin-secreting β cells renders them susceptible to the autoimmune attack, and is associated with a diminution in β-cells function (e.g., less insulin production and/or insulin secretion) and possibly also with an enhanced apoptosis rate. The diabetes-supportive effect of CD44 expression on β cells was assessed by the TUNEL assay and further strengthened by functional assays exhibiting increased nitric oxide release, reduced insulin secretion after glucose stimulation and decreased insulin content in β cells. All these parameters could not be detected in CD44-deficient islets. We further suggest that HA-binding to CD44-expressing β cells is implicated in β-cell demise. Altogether, these data agree with the concept that CD44 is a receptor capable of modulating cell fate. This finding is important for other pathologies (e.g., cancer, neurodegenerative diseases) in which CD44 and HA appear to be implicated. PMID:26624007

  18. Can CD44 Be a Mediator of Cell Destruction? The Challenge of Type 1 Diabetes.

    Directory of Open Access Journals (Sweden)

    Nathalie Assayag-Asherie

    Full Text Available CD44 is a multi-functional receptor with multiple of isoforms engaged in modulation of cell trafficking and transmission of apoptotic signals. We have previously shown that injection of anti-CD44 antibody into NOD mice induced resistance to type 1 diabetes (T1D. In this communication we describe our efforts to understand the mechanism underlying this effect. We found that CD44-deficient NOD mice develop stronger resistance to T1D than wild-type littermates. This effect is not explained by the involvement of CD44 in cell migration, because CD44-deficient inflammatory cells surprisingly had greater invasive potential than the corresponding wild type cells, probably owing to molecular redundancy. We have previously reported and we show here again that CD44 expression and hyaluronic acid (HA, the principal ligand for CD44 accumulation are detected in pancreatic islets of diabetic NOD mice, but not of non-diabetic DBA/1 mice. Expression of CD44 on insulin-secreting β cells renders them susceptible to the autoimmune attack, and is associated with a diminution in β-cells function (e.g., less insulin production and/or insulin secretion and possibly also with an enhanced apoptosis rate. The diabetes-supportive effect of CD44 expression on β cells was assessed by the TUNEL assay and further strengthened by functional assays exhibiting increased nitric oxide release, reduced insulin secretion after glucose stimulation and decreased insulin content in β cells. All these parameters could not be detected in CD44-deficient islets. We further suggest that HA-binding to CD44-expressing β cells is implicated in β-cell demise. Altogether, these data agree with the concept that CD44 is a receptor capable of modulating cell fate. This finding is important for other pathologies (e.g., cancer, neurodegenerative diseases in which CD44 and HA appear to be implicated.

  19. Mesenchymal Stem Cell Therapy in Diabetes Mellitus: Progress and Challenges

    Directory of Open Access Journals (Sweden)

    Nagwa El-Badri

    2013-01-01

    Full Text Available Advanced type 2 diabetes mellitus is associated with significant morbidity and mortality due to cardiovascular, nervous, and renal complications. Attempts to cure diabetes mellitus using islet transplantation have been successful in providing a source for insulin secreting cells. However, limited donors, graft rejection, the need for continued immune suppression, and exhaustion of the donor cell pool prompted the search for a more sustained source of insulin secreting cells. Stem cell therapy is a promising alternative for islet transplantation in type 2 diabetic patients who fail to control hyperglycemia even with insulin injection. Autologous stem cell transplantation may provide the best outcome for those patients, since autologous cells are readily available and do not entail prolonged hospital stays or sustained immunotoxic therapy. Among autologous adult stem cells, mesenchymal stem cells (MSCs therapy has been applied with varying degrees of success in both animal models and in clinical trials. This review will focus on the advantages of MSCs over other types of stem cells and the possible mechanisms by which MSCs transplant restores normoglycemia in type 2 diabetic patients. Sources of MSCs including autologous cells from diabetic patients and the use of various differentiation protocols in relation to best transplant outcome will be discussed.

  20. Dynamics and Synchrony of Pancreatic beta-cells and Islets

    DEFF Research Database (Denmark)

    Pedersen, Morten Gram

    2006-01-01

    description of these processes and their interactions would provide important input in the search for a better treatment of the disease. The thesis describes several aspects of mathematical modeling of beta-cells relevant for the understanding of glucose stimulated insulin secretion. It consists...... and the synchronized behavior of many coupled beta-cells as well as to the synchrony of islets. Rather than developing new biophysical models, the thesis investigates existing models, their integration and simplifications, and analyzed the corresponding dynamics, in order to use these models for investigating...

  1. Evaluation of insulin expression and secretion in genetically engineered gut K and L-cells

    Directory of Open Access Journals (Sweden)

    Ahmad Zalinah

    2012-09-01

    Full Text Available Abstract Background Gene therapy could provide an effective treatment of diabetes. Previous studies have investigated the potential for several cell and tissue types to produce mature and active insulin. Gut K and L-cells could be potential candidate hosts for gene therapy because of their special features. Results In this study, we isolated gut K and L-cells to compare the potential of both cell types to produce insulin when exposed to similar conditions. The isolated pure K and L-cells were transfected with recombinant plasmids encoding insulin and with specific promoters for K or L-cells. Insulin expression was studied in response to glucose or meat hydrolysate. We found that glucose and meat hydrolysate efficiently induced insulin secretion from K and L-cells. However, the effects of meat hydrolysate on insulin secretion were more potent in both cells compared with glucose. Results of enzyme-linked immunosorbent assays showed that L-cells secreted more insulin compared with K-cells regardless of the stimulator, although this difference was not statistically significant. Conclusion The responses of K and L-cells to stimulation with glucose or meat hydrolysate were generally comparable. Therefore, both K and L-cells show similar potential to be used as surrogate cells for insulin gene expression in vitro. The potential use of these cells for diabetic gene therapy warrants further investigation.

  2. Overexpression of Insig-1 protects β cell against glucolipotoxicity via SREBP-1c

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    Chen Ke

    2011-08-01

    Full Text Available Abstract Background High glucose induced lipid synthesis leads to β cell glucolipotoxicity. Sterol regulatory element binding protein-1c (SREBP-1c is reported to be partially involved in this process. Insulin induced gene-1 (Insig-1 is an important upstream regulator of Insig-1-SREBPs cleavage activating protein (SCAP-SREBP-1c pathway. Insig-1 effectively blocks the transcription of SREBP-1c, preventing the activation of the genes for lipid biosynthesis. In this study, we aimed to investigate whether Insig-1 protects β cells against glucolipotoxicity. Methods An Insig-1 stable cell line was generated by overexpression of Insig-1 in INS-1 cells. The expression of Insig-1 was evaluated by RT-PCR and Western blotting, then, cells were then treated with standard (11.2 mM or high (25.0 mM glucose for 0 h, 24 h and 72 h. Cell viability, apoptosis, glucose stimulated insulin secretion (GSIS, lipid metabolism and mRNA expression of insulin secretion relevant genes such as IRS-2, PDX-1, GLUT-2, Insulin and UCP-2 were evaluated. Results We found that Insig-1 suppressed the high glucose induced SREBP-1c mRNA and protein expression. Our results also showed that Insig-1 overexpression protected β cells from ER stress-induced apoptosis by regulating the proteins expressed in the IRE1α pathway, such as p-IRE1α, p-JNK, CHOP and BCL-2. In addition, Insig-1 up-regulated the expression of IRS-2, PDX-1, GLUT-2 and Insulin, down-regulated the expression of UCP-2 and improved glucose stimulated insulin secretion (GSIS. Finally, we found that Insig-1 inhibited the lipid accumulation and free fatty acid (FFA synthesis in a time-dependent manner. Conclusions There results suggest that Insig-1 may play a critical role in protecting β cells against glucolipotoxicity by regulating the expression of SREBP-1c.

  3. Transgenic overexpression of active calcineurin in beta-cells results in decreased beta-cell mass and hyperglycemia.

    Directory of Open Access Journals (Sweden)

    Ernesto Bernal-Mizrachi

    2010-08-01

    Full Text Available Glucose modulates beta-cell mass and function through an initial depolarization and Ca(2+ influx, which then triggers a number of growth regulating signaling pathways. One of the most important downstream effectors in Ca(2+ signaling is the calcium/Calmodulin activated serine threonine phosphatase, calcineurin. Recent evidence suggests that calcineurin/NFAT is essential for beta-cell proliferation, and that in its absence loss of beta-cells results in diabetes. We hypothesized that in contrast, activation of calcineurin might result in expansion of beta-cell mass and resistance to diabetes.To determine the role of activation of calcineurin signaling in the regulation of pancreatic beta-cell mass and proliferation, we created mice that expressed a constitutively active form of calcineurin under the insulin gene promoter (caCn(RIP. To our surprise, these mice exhibited glucose intolerance. In vitro studies demonstrated that while the second phase of Insulin secretion is enhanced, the overall insulin secretory response was conserved. Islet morphometric studies demonstrated decreased beta-cell mass suggesting that this was a major component responsible for altered Insulin secretion and glucose intolerance in caCn(RIP mice. The reduced beta-cell mass was accompanied by decreased proliferation and enhanced apoptosis.Our studies identify calcineurin as an important factor in controlling glucose homeostasis and indicate that chronic depolarization leading to increased calcineurin activity may contribute, along with other genetic and environmental factors, to beta-cell dysfunction and diabetes.

  4. The F-actin modifier villin regulates insulin granule dynamics and exocytosis downstream of islet cell autoantigen 512

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    Hassan Mziaut

    2016-08-01

    Full Text Available Objective: Insulin release from pancreatic islet β cells should be tightly controlled to avoid hypoglycemia and insulin resistance. The cortical actin cytoskeleton is a gate for regulated exocytosis of insulin secretory granules (SGs by restricting their mobility and access to the plasma membrane. Prior studies suggest that SGs interact with F-actin through their transmembrane cargo islet cell autoantigen 512 (Ica512 (also known as islet antigen 2/Ptprn. Here we investigated how Ica512 modulates SG trafficking and exocytosis. Methods: Transcriptomic changes in Ica512−/− mouse islets were analyzed. Imaging as well as biophysical and biochemical methods were used to validate if and how the Ica512-regulated gene villin modulates insulin secretion in mouse islets and insulinoma cells. Results: The F-actin modifier villin was consistently downregulated in Ica512−/− mouse islets and in Ica512-depleted insulinoma cells. Villin was enriched at the cell cortex of β cells and dispersed villin−/− islet cells were less round and less deformable. Basal mobility of SGs in villin-depleted cells was enhanced. Moreover, in cells depleted either of villin or Ica512 F-actin cages restraining cortical SGs were enlarged, basal secretion was increased while glucose-stimulated insulin release was blunted. The latter changes were reverted by overexpressing villin in Ica512-depleted cells, but not vice versa. Conclusion: Our findings show that villin controls the size of the F-actin cages restricting SGs and, thus, regulates their dynamics and availability for exocytosis. Evidence that villin acts downstream of Ica512 also indicates that SGs directly influence the remodeling properties of the cortical actin cytoskeleton for tight control of insulin secretion. Keywords: F-actin, Granules, Ica512, Insulin, Secretion, Villin

  5. Regulation of proliferation and functioning of transplanted cells by using herpes simplex virus thymidine kinase gene in mice.

    Science.gov (United States)

    Tsujimura, Mari; Kusamori, Kosuke; Oda, Chihiro; Miyazaki, Airi; Katsumi, Hidemasa; Sakane, Toshiyasu; Nishikawa, Makiya; Yamamoto, Akira

    2018-04-10

    Though cell transplantation is becoming an attractive therapeutic method, uncontrolled cell proliferation or overexpression of cellular functions could cause adverse effects. These unfavorable outcomes could be avoided by regulating the proliferation or functioning of transplanted cells. In this study, we used a combination of the herpes simplex virus thymidine kinase (HSVtk) gene, a suicide gene, and ganciclovir (GCV) to control the proliferation and functioning of insulin-secreting cells after transplantation in diabetic mice. Mouse pancreatic β cell line MIN6 cells were selected as insulin-secreting cells for transfection with the HSVtk gene to obtain MIN6/HSVtk cells. Proliferation of MIN6/HSVtk cells was suppressed by GCV in a concentration-dependent manner; 0.25 μg/mL GCV maintained a constant number of MIN6/HSVtk cells for at least 16 days. MIN6 or MIN6/HSVtk cells were then transplanted to streptozotocin-induced diabetic mice. Mice transplanted with MIN6 cells exhibited hypoglycemia irrespective of GCV administration. In contrast, normal (around 150 mg/dL) blood glucose levels were maintained in mice transplanted with MIN6/HSVtk cells by a daily administration of 50 mg/kg of GCV. These results indicate that controlling the proliferation and functioning of HSVtk gene-expressing cells by GCV could greatly improve the usefulness and safety of cell-based therapy. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Chronic antidiabetic sulfonylureas in vivo: reversible effects on mouse pancreatic beta-cells.

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    Maria Sara Remedi

    2008-10-01

    Full Text Available Pancreatic beta-cell ATP-sensitive potassium (K ATP channels are critical links between nutrient metabolism and insulin secretion. In humans, reduced or absent beta-cell K ATP channel activity resulting from loss-of-function K ATP mutations induces insulin hypersecretion. Mice with reduced K ATP channel activity also demonstrate hyperinsulinism, but mice with complete loss of K ATP channels (K ATP knockout mice show an unexpected insulin undersecretory phenotype. Therefore we have proposed an "inverse U" hypothesis to explain the response to enhanced excitability, in which excessive hyperexcitability drives beta-cells to insulin secretory failure without cell death. Many patients with type 2 diabetes treated with antidiabetic sulfonylureas (which inhibit K ATP activity and thereby enhance insulin secretion show long-term insulin secretory failure, which we further suggest might reflect a similar progression.To test the above hypotheses, and to mechanistically investigate the consequences of prolonged hyperexcitability in vivo, we used a novel approach of implanting mice with slow-release sulfonylurea (glibenclamide pellets, to chronically inhibit beta-cell K ATP channels. Glibenclamide-implanted wild-type mice became progressively and consistently diabetic, with significantly (p < 0.05 reduced insulin secretion in response to glucose. After 1 wk of treatment, these mice were as glucose intolerant as adult K ATP knockout mice, and reduction of secretory capacity in freshly isolated islets from implanted animals was as significant (p < 0.05 as those from K ATP knockout animals. However, secretory capacity was fully restored in islets from sulfonylurea-treated mice within hours of drug washout and in vivo within 1 mo after glibenclamide treatment was terminated. Pancreatic immunostaining showed normal islet size and alpha-/beta-cell distribution within the islet, and TUNEL staining showed no evidence of apoptosis.These results demonstrate that

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    Research highlights: → GLP-1 prevents AGEs-induced cell death. → GLP-1 prevents AGEs-induced oxidative stress. → GLP-1 ameliorated AGEs-induced cell dysfunction. → GLP-1 attenuates AGEs-induced RAGE increment. → 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.

  8. Collagen esterification enhances the function and survival of pancreatic β cells in 2D and 3D culture systems

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Jae Hyung [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Kim, Yang Hee [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Jeong, Seong Hee; Lee, Song [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Park, Si-Nae [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Shim, In Kyong, E-mail: shimiink@gmail.com [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Kim, Song Cheol, E-mail: drksc@amc.seoul.kr [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Department of Surgery, University of Ulsan College of Medicine & Asan Medical Center, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of)

    2015-08-07

    Collagen, one of the most important components of the extracellular matrix (ECM), may play a role in the survival of pancreatic islet cells. In addition, chemical modifications that change the collagen charge profile to a net positive charge by esterification have been shown to increase the adhesion and proliferation of various cell types. The purpose of this study was to characterize and compare the effects of native collagen (NC) and esterified collagen (EC) on β cell function and survival. After isolation by the collagenase digestion technique, rat islets were cultured with NC and EC in 2 dimensional (2D) and 3 dimensional (3D) environments for a long-term duration in vitro. The cells were assessed for islet adhesion, morphology, viability, glucose-induced insulin secretion, and mRNA expression of glucose metabolism-related genes, and visualized by scanning electron microscopy (SEM). Islet cells attached tightly in the NC group, but islet cell viability was similar in both the NC and EC groups. Glucose-stimulated insulin secretion was higher in the EC group than in the NC group in both 2D and 3D culture. Furthermore, the mRNA expression levels of glucokinase in the EC group were higher than those in the NC group and were associated with glucose metabolism and insulin secretion. Finally, SEM observation confirmed that islets had more intact component cells on EC sponges than on NC sponges. These results indicate that modification of collagen may offer opportunities to improve function and viability of islet cells. - Highlights: • We changed the collagen charge profile to a net positive charge by esterification. • Islets cultured on esterified collagen improved survival in both 2D and 3D culture. • Islets cultured on esterified collagen enhanced glucose-stimulated insulin release. • High levels of glucokinase mRNA may be associated with increased insulin release.

  9. Collagen esterification enhances the function and survival of pancreatic β cells in 2D and 3D culture systems

    International Nuclear Information System (INIS)

    Ko, Jae Hyung; Kim, Yang Hee; Jeong, Seong Hee; Lee, Song; Park, Si-Nae; Shim, In Kyong; Kim, Song Cheol

    2015-01-01

    Collagen, one of the most important components of the extracellular matrix (ECM), may play a role in the survival of pancreatic islet cells. In addition, chemical modifications that change the collagen charge profile to a net positive charge by esterification have been shown to increase the adhesion and proliferation of various cell types. The purpose of this study was to characterize and compare the effects of native collagen (NC) and esterified collagen (EC) on β cell function and survival. After isolation by the collagenase digestion technique, rat islets were cultured with NC and EC in 2 dimensional (2D) and 3 dimensional (3D) environments for a long-term duration in vitro. The cells were assessed for islet adhesion, morphology, viability, glucose-induced insulin secretion, and mRNA expression of glucose metabolism-related genes, and visualized by scanning electron microscopy (SEM). Islet cells attached tightly in the NC group, but islet cell viability was similar in both the NC and EC groups. Glucose-stimulated insulin secretion was higher in the EC group than in the NC group in both 2D and 3D culture. Furthermore, the mRNA expression levels of glucokinase in the EC group were higher than those in the NC group and were associated with glucose metabolism and insulin secretion. Finally, SEM observation confirmed that islets had more intact component cells on EC sponges than on NC sponges. These results indicate that modification of collagen may offer opportunities to improve function and viability of islet cells. - Highlights: • We changed the collagen charge profile to a net positive charge by esterification. • Islets cultured on esterified collagen improved survival in both 2D and 3D culture. • Islets cultured on esterified collagen enhanced glucose-stimulated insulin release. • High levels of glucokinase mRNA may be associated with increased insulin release

  10. Antioxidant and regulatory role of mitochondrial uncoupling protein UCP2 in pancreatic beta-cells

    Czech Academy of Sciences Publication Activity Database

    Ježek, Petr; Olejár, Tomáš; Smolková, Katarína; Ježek, Jan; Dlasková, Andrea; Plecitá-Hlavatá, Lydie; Zelenka, Jaroslav; Špaček, Tomáš; Engstová, Hana; Reguera Pajuelo, David; Jabůrek, Martin

    2014-01-01

    Roč. 63, Suppl.1 (2014), S73-S91 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GAP302/10/0346; GA ČR(CZ) GAP305/12/1247; GA ČR(CZ) GPP304/10/P204; GA MŠk(CZ) EE2.3.30.0025 Institutional support: RVO:67985823 Keywords : mitochondria * uncoupling protein UCP2 * pancreatic beta-cells * reactive oxygen species * glucose-stimulated insulin secretion Subject RIV: EA - Cell Biology Impact factor: 1.293, year: 2014

  11. Effects of the antitumor drug OSI-906, a dual inhibitor of IGF-1 receptor and insulin receptor, on the glycemic control, β-cell functions, and β-cell proliferation in male mice.

    Science.gov (United States)

    Shirakawa, Jun; Okuyama, Tomoko; Yoshida, Eiko; Shimizu, Mari; Horigome, Yuka; Tuno, Takayuki; Hayasaka, Moe; Abe, Shiori; Fuse, Masahiro; Togashi, Yu; Terauchi, Yasuo

    2014-06-01

    The IGF-1 receptor has become a therapeutic target for the treatment of cancer. The efficacy of OSI-906 (linstinib), a dual inhibitor of IGF-1 receptor and insulin receptor, for solid cancers has been examined in clinical trials. The effects of OSI-906, however, on the blood glucose levels and pancreatic β-cell functions have not yet been reported. We investigated the impact of OSI-906 on glycemic control, insulin secretion, β-cell mass, and β-cell proliferation in male mice. Oral administration of OSI-906 worsened glucose tolerance in a dose-dependent manner in the wild-type mice. OSI-906 at a dose equivalent to the clinical daily dose (7.5 mg/kg) transiently evoked glucose intolerance and hyperinsulinemia. Insulin receptor substrate (IRS)-2-deficient mice and mice with diet-induced obesity, both models of peripheral insulin resistance, exhibited more severe glucose intolerance after OSI-906 administration than glucokinase-haploinsufficient mice, a model of impaired insulin secretion. Phloridzin improved the hyperglycemia induced by OSI-906 in mice. In vitro, OSI-906 showed no effect on insulin secretion from isolated islets. After daily administration of OSI-906 for a week to mice, the β-cell mass and β-cell proliferation rate were significantly increased. The insulin signals in the β-cells were apparently unaffected in those mice. Taken together, the results suggest that OSI-906 could exacerbate diabetes, especially in patients with insulin resistance. On the other hand, the results suggest that the β-cell mass may expand in response to chemotherapy with this drug.

  12. Cell differentiation: therapeutical challenges in diabetes.

    Science.gov (United States)

    Roche, Enrique; Vicente-Salar, Nestor; Arribas, Maribel; Paredes, Beatriz

    2012-01-01

    Stem cells, derived from either embryonic or adult tissues, are considered to be potential sources of insulin-secreting cells to be transplanted into type 1 and advanced stages of type 2 diabetic patients. Many laboratories have considered this possibility, resulting in a large amount of published protocols, with a wide degree of complexity among them. Our group was the first to report that it was possible to obtain insulin-secreting cells from mouse embryonic stem cells, proving the feasibility of this new challenge. The same observation was immediately reported using human embryonic stem cells. However, the resulting cell product was not properly characterised, affecting the reproducibility of the protocol by other groups. A more elaborated protocol was developed by Lumelsky and co-workers, demonstrating that neuroectodermal cells could be an alternative source for insulin-producing cells. However, the resulting cells of this protocol produced low amounts of the hormone. This aimed other groups to perform key changes in order to improve the insulin content of the resulting cells. Recently, Baetge's group has published a new protocol based on the knowledge accumulated in pancreatic development. In this protocol, human embryonic stem cells were differentiated into islet-like structures through a five step protocol, emulating the key steps during embryonic development of the endocrine pancreas. The final cell product, however, seemed to be in an immature state, thus further improvement is required. Despite this drawback, the protocol represents the culmination of work performed by different groups and offers new research challenges for the investigators in this exciting field. Concerning adult stem cells, the possibility of identifying pancreatic precursors or of reprogramming extrapancreatic derived cells are key possibilities that may circumvent the problems that appear when using embryonic stem cells, such as immune rejection and tumour formation.

  13. The putative imidazoline receptor agonist, harmane, promotes intracellular calcium mobilisation in pancreatic beta-cells.

    Science.gov (United States)

    Squires, Paul E; Hills, Claire E; Rogers, Gareth J; Garland, Patrick; Farley, Sophia R; Morgan, Noel G

    2004-10-06

    beta-Carbolines (including harmane and pinoline) stimulate insulin secretion by a mechanism that may involve interaction with imidazoline I(3)-receptors but which also appears to be mediated by actions that are additional to imidazoline receptor agonism. Using the MIN6 beta-cell line, we now show that both the imidazoline I(3)-receptor agonist, efaroxan, and the beta-carboline, harmane, directly elevate cytosolic Ca(2+) and increase insulin secretion but that these responses display different characteristics. In the case of efaroxan, the increase in cytosolic Ca(2+) was readily reversible, whereas, with harmane, the effect persisted beyond removal of the agonist and resulted in the development of a repetitive train of Ca(2+)-oscillations whose frequency, but not amplitude, was concentration-dependent. Initiation of the Ca(2+)-oscillations by harmane was independent of extracellular calcium but was sensitive to both dantrolene and high levels (20 mM) of caffeine, suggesting the involvement of ryanodine receptor-gated Ca(2+)-release. The expression of ryanodine receptor-1 and ryanodine receptor-2 mRNA in MIN6 cells was confirmed using reverse transcription-polymerase chain reaction (RT-PCR) and, since low concentrations of caffeine (1 mM) or thimerosal (10 microM) stimulated increases in [Ca(2+)](i), we conclude that ryanodine receptors are functional in these cells. Furthermore, the increase in insulin secretion induced by harmane was attenuated by dantrolene, consistent with the involvement of ryanodine receptors in mediating this response. By contrast, the smaller insulin secretory response to efaroxan was unaffected by dantrolene. Harmane-evoked changes in cytosolic Ca(2+) were maintained by nifedipine-sensitive Ca(2+)-influx, suggesting the involvement of L-type voltage-gated Ca(2+)-channels. Taken together, these data imply that harmane may interact with ryanodine receptors to generate sustained Ca(2+)-oscillations in pancreatic beta-cells and that this effect

  14. The Generation of Insulin Producing Cells from Human Mesenchymal Stem Cells by MiR-375 and Anti-MiR-9.

    Science.gov (United States)

    Jafarian, Arefeh; Taghikani, Mohammad; Abroun, Saeid; Allahverdi, Amir; Lamei, Maryam; Lakpour, Niknam; Soleimani, Masoud

    2015-01-01

    MicroRNAs (miRNAs) are a group of endogenous small non-coding RNAs that regulate gene expression at the post-transcriptional level. A number of studies have led to the notion that some miRNAs have key roles in control of pancreatic islet development and insulin secretion. Based on some studies on miRNAs pattern, the researchers in this paper investigated the pancreatic differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) by up-regulation of miR-375 and down-regulation of miR-9 by lentiviruses containing miR-375 and anti-miR-9. After 21 days of induction, islet-like clusters containing insulin producing cells (IPCs) were confirmed by dithizone (DTZ) staining. The IPCs and β cell specific related genes and proteins were detected using qRT-PCR and immunofluorescence on days 7, 14 and 21 of differentiation. Glucose challenge test was performed at different concentrations of glucose so extracellular and intracellular insulin and C-peptide were assayed using ELISA kit. Although derived IPCs by miR-375 alone were capable to express insulin and other endocrine specific transcription factors, the cells lacked the machinery to respond to glucose. It was found that over-expression of miR-375 led to a reduction in levels of Mtpn protein in derived IPCs, while treatment with anti-miR-9 following miR-375 over-expression had synergistic effects on MSCs differentiation and insulin secretion in a glucose-regulated manner. The researchers reported that silencing of miR-9 increased OC-2 protein in IPCs that may contribute to the observed glucose-regulated insulin secretion. Although the roles of miR-375 and miR-9 are well known in pancreatic development and insulin secretion, the use of these miRNAs in transdifferentiation was never demonstrated. These findings highlight miRNAs functions in stem cells differentiation and suggest that they could be used as therapeutic tools for gene-based therapy in diabetes mellitus.

  15. Mitochondrial oxidative stress contributes differently to rat pancreatic islet cell apoptosis and insulin secretory defects after prolonged culture in a low non-stimulating glucose concentration.

    Science.gov (United States)

    Roma, L P; Pascal, S M; Duprez, J; Jonas, J-C

    2012-08-01

    Pancreatic beta cells chronically exposed to low glucose concentrations show signs of oxidative stress, loss of glucose-stimulated insulin secretion (GSIS) and increased apoptosis. Our aim was to confirm the role of mitochondrial oxidative stress in rat islet cell apoptosis under these culture conditions and to evaluate whether its reduction similarly improves survival and GSIS. Apoptosis, oxidative stress-response gene mRNA expression and glucose-induced stimulation of mitochondrial metabolism, intracellular Ca(2+) concentration and insulin secretion were measured in male Wistar rat islets cultured for 1 week in RPMI medium containing 5-10 mmol/l glucose with or without manganese(III)tetrakis(4-benzoic acid)porphyrin (MnTBAP) or N-acetyl-L-: cysteine (NAC). Oxidative stress was measured in islet cell clusters cultured under similar conditions using cytosolic and mitochondrial redox-sensitive green fluorescent protein (roGFP1/mt-roGFP1). Prolonged culture in 5 vs 10 mmol/l glucose increased mt-roGFP1 (but not roGFP1) oxidation followed by beta cell apoptosis and loss of GSIS resulting from reduced insulin content, mitochondrial metabolism, Ca(2+) influx and Ca(2+)-induced secretion. Tolbutamide-induced, but not high K(+)-induced, Ca(2+) influx was also suppressed. Under these conditions, MnTBAP, but not NAC, triggered parallel ~50-70% reductions in mt-roGFP1 oxidation and beta cell apoptosis, but failed to protect against the loss of GSIS despite significant improvement in glucose-induced and tolbutamide-induced Ca(2+) influx. Mitochondrial oxidative stress contributes differently to rat pancreatic islet cell apoptosis and insulin secretory defects during culture in a low glucose concentration. Thus, targeting beta cell survival may not be sufficient to restore insulin secretion when beta cells suffer from prolonged mitochondrial oxidative stress, e.g. in the context of reduced glucose metabolism.

  16. Geometric effect of the hydrogel grid structure on in vitro formation of homogeneous MIN6 cell clusters.

    Science.gov (United States)

    Bae, Chae Yun; Min, Mun-kyeong; Kim, Hail; Park, Je-Kyun

    2014-07-07

    A microstructure-based hydrogel was employed to study the relationship between spatial specificity and cellular behavior, including cell fate, proliferation, morphology, and insulin secretion in pancreatic β-cells. To effectively form homogeneous cell clusters in vitro, we made cell-containing hydrogel membrane constructs with an adapted grid structure based on a hexagonal micropattern. Homogeneous cell clusters (average diameter: 83.6 ± 14.2 μm) of pancreatic insulinoma (MIN6) cells were spontaneously generated in the floating hydrogel membrane constructs, including a hexagonal grid structure (size of cavity: 100 μm, interval between cavities: 30 μm). Interestingly, 3D clustering of MIN6 cells mimicking the structure of pancreatic islets was coalesced into a merged aggregate attaching to each hexagonal cavity of the hydrogel grid structure. The fate and insulin secretion of homogeneous cell clusters in the hydrogel grid structure were also assessed. The results of these designable hydrogel-cell membrane constructs suggest that facultative in vitro β-cell proliferation and maintenance can be applied to biofunctional assessments.

  17. Divalent metal transporter 1 regulates iron-mediated ROS and pancreatic ß cell fate in response to cytokines

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Tonnesen, Morten Fog; Madsen, Andreas Nygaard

    2012-01-01

    Reactive oxygen species (ROS) contribute to target-cell damage in inflammatory and iron-overload diseases. Little is known about iron transport regulation during inflammatory attack. Through a combination of in vitro and in vivo studies, we show that the proinflammatory cytokine IL-1ß induces...... knockout islets is defective, highlighting a physiological role of iron and ROS in the regulation of insulin secretion. Dmt1 knockout mice are protected against multiple low-dose streptozotocin and high-fat diet-induced glucose intolerance, models of type 1 and type 2 diabetes, respectively. Thus, ß cells...

  18. Insulin Secretion in Bantu with Siderosis or Hepatoma*

    African Journals Online (AJOL)

    1971-08-14

    Aug 14, 1971 ... Department of Physiology, Medical School, University of Pretoria. SUMMARY. The IR and concomitant GTC was evaluated in 10 siderotic. Bantu patients and ... most probably to significant low deposits in the pancreas. A similar relatively low IR in the presence of elevated blood glucose levels was found in ...

  19. Radioimmunologic analysis of insulin secretion during acute radiation sickness

    Energy Technology Data Exchange (ETDEWEB)

    Barkalaya, A I

    1975-01-01

    Rats were subjected to whole-body gamma irradiation (750 rad) and the secretory activity of the insular apparatus was studied radioimmunologically, using insulin labelled with iodine-125. The post-radiation dynamics of the insulin concentration in the blood were shown to have a phase character. The insulin level had risen after 1, 3 and 8 days. After 2 days the hormone concentration had dropped significantly and become two times lower than normal. After the other time intervals, the concentration of insulin in the blood varied within normal limits.

  20. Conditioned insulin secretion and meal feeding in rats.

    Science.gov (United States)

    Woods, S C; Vasselli, J R; Kaestner, E; Szakmary, G A; Milburn, P; Vitiello, M V

    1977-02-01

    Previous researchers have reported that rats placed upon a feeding regimen such that they receive only 2 hr of food per day (meal-fed rats) develop hyperinsulinemia at the time of the day associated with feeding, even in the absence of food. Controls fed ad lib had no such response. In a series of several experiments, meal-fed rats had elevated insulin levels at only the specific time of the day associated with feeding, and the increment of insulin at that time could be eliminated with atropine. Free-feeding controls, on the other hand, always had higher insulin levels than the meal-fed rats, did not have an elevation of insulin at the time of the day that the meal-fed rats normally ate, and had insulin values that were unaffected by atropine. Further experimentation showed that hyperinsulinemia could become associated with arbitrary stimuli always associated with eating for meal-fed rats. It is concluded that the hyperinsulinemia of meal-fed rats associated with their feeding time is a learned response.

  1. EX4 stabilizes and activates Nrf2 via PKCδ, contributing to the prevention of oxidative stress-induced pancreatic beta cell damage

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mi-Hwi; Kim, Eung-Hwi [College of Pharmacy, Gachon Institute of Pharmaceutical Science, Gachon University, Yeonsu-ku, Incheon (Korea, Republic of); Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Yeonsu-ku, Incheon (Korea, Republic of); Jung, Hye Seung [Department of Internal Medicine, Seoul National University College of Medicine, Seoul (Korea, Republic of); Yang, Dongki [Department of Physiology, Gachon University College of Medicine, Incheon (Korea, Republic of); Park, Eun-Young, E-mail: parkey@mokpo.ac.kr [College of Pharmacy, Natural Medicine Research Institute, Mokpo National University, Muan-gun, Jeonnam (Korea, Republic of); Jun, Hee-Sook, E-mail: hsjun@gachon.ac.kr [College of Pharmacy, Gachon Institute of Pharmaceutical Science, Gachon University, Yeonsu-ku, Incheon (Korea, Republic of); Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Yeonsu-ku, Incheon (Korea, Republic of); Gachon Medical Research Institute, Gil Hospital, Incheon (Korea, Republic of)

    2017-01-15

    Oxidative stress in pancreatic beta cells can inhibit insulin secretion and promote apoptotic cell death. Exendin-4 (EX4), a glucagon-like peptide-1 receptor agonist, can suppress beta cell apoptosis, improve beta cell function and protect against oxidative damage. In this study, we investigated the molecular mechanisms for antioxidative effects of EX4 in pancreatic beta cells. INS-1 cells, a rat insulinoma cell line, were pretreated with EX4 and exposed to palmitate or H{sub 2}O{sub 2}. Reactive oxygen species (ROS) production, and glutathione and insulin secretion were measured. The mRNA and protein expression levels of antioxidant genes were examined. The level of nuclear factor erythroid 2-related factor 2 (Nrf2), its binding to antioxidant response element (ARE), and its ubiquination in the presence of EX4 were determined. The Nrf2 signaling pathway was determined using rottlerin (protein kinase [PK]Cδ inhibitor), H89 (PKA inhibitor) and LY294002 (phosphatidylinositide 3-kinase [PI3K] inhibitor). EX4 treatment decreased ROS production, recovered cellular glutathione levels and insulin secretion in the presence of oxidative stress in INS-1 cells. The expression levels of glutamate-cysteine ligase catalytic subunit and heme oxygenase-1 were increased by EX4 treatment. EX4 promoted Nrf2 translocation, ARE binding activity and enhanced stabilization of Nrf2 by inhibition of ubiquitination. Knockdown of Nrf2 abolished the effect of EX4 on increased insulin secretion. Inhibition of PKCδ attenuated Nrf2 translocation and antioxidative gene expression by EX4 treatment. We suggest that EX4 activates and stabilizes Nrf2 through PKCδ activation, contributing to the increase of antioxidant gene expression and consequently improving beta cell function in the presence of oxidative stress. - Highlights: • EX4 protects against oxidative stress-induced pancreatic beta cell dysfunction. • EX4 increases antioxidant gene expression. • Antioxidative effect of EX4 is

  2. EX4 stabilizes and activates Nrf2 via PKCδ, contributing to the prevention of oxidative stress-induced pancreatic beta cell damage

    International Nuclear Information System (INIS)

    Kim, Mi-Hwi; Kim, Eung-Hwi; Jung, Hye Seung; Yang, Dongki; Park, Eun-Young; Jun, Hee-Sook

    2017-01-01

    Oxidative stress in pancreatic beta cells can inhibit insulin secretion and promote apoptotic cell death. Exendin-4 (EX4), a glucagon-like peptide-1 receptor agonist, can suppress beta cell apoptosis, improve beta cell function and protect against oxidative damage. In this study, we investigated the molecular mechanisms for antioxidative effects of EX4 in pancreatic beta cells. INS-1 cells, a rat insulinoma cell line, were pretreated with EX4 and exposed to palmitate or H 2 O 2 . Reactive oxygen species (ROS) production, and glutathione and insulin secretion were measured. The mRNA and protein expression levels of antioxidant genes were examined. The level of nuclear factor erythroid 2-related factor 2 (Nrf2), its binding to antioxidant response element (ARE), and its ubiquination in the presence of EX4 were determined. The Nrf2 signaling pathway was determined using rottlerin (protein kinase [PK]Cδ inhibitor), H89 (PKA inhibitor) and LY294002 (phosphatidylinositide 3-kinase [PI3K] inhibitor). EX4 treatment decreased ROS production, recovered cellular glutathione levels and insulin secretion in the presence of oxidative stress in INS-1 cells. The expression levels of glutamate-cysteine ligase catalytic subunit and heme oxygenase-1 were increased by EX4 treatment. EX4 promoted Nrf2 translocation, ARE binding activity and enhanced stabilization of Nrf2 by inhibition of ubiquitination. Knockdown of Nrf2 abolished the effect of EX4 on increased insulin secretion. Inhibition of PKCδ attenuated Nrf2 translocation and antioxidative gene expression by EX4 treatment. We suggest that EX4 activates and stabilizes Nrf2 through PKCδ activation, contributing to the increase of antioxidant gene expression and consequently improving beta cell function in the presence of oxidative stress. - Highlights: • EX4 protects against oxidative stress-induced pancreatic beta cell dysfunction. • EX4 increases antioxidant gene expression. • Antioxidative effect of EX4 is mediated by

  3. Clinical characteristics and beta cell function in Chinese patients with newly diagnosed type 2 diabetes mellitus with different levels of serum triglyceride.

    Science.gov (United States)

    Zheng, Shuang; Zhou, Huan; Han, Tingting; Li, Yangxue; Zhang, Yao; Liu, Wei; Hu, Yaomin

    2015-04-29

    To explore clinical characteristics and beta cell function in Chinese patients with newly diagnosed drug naive type 2 diabetes mellitus (T2DM) with different levels of serum triglyceride (TG). Patients with newly diagnosed T2DM (n = 624) were enrolled and divided into different groups according to levels of serum TG. All patients underwent oral glucose tolerance tests and insulin releasing tests. Demographic data, lipid profiles, glucose levels, and insulin profiles were compared between different groups. Basic insulin secretion function index (homeostasis model assessment for beta cell function index, HOMA-β), modified beta cell function index (MBCI), glucose disposition indices (DI), and early insulin secretion function index (insulinogenic index, IGI) were used to evaluate the beta cell function. Patients of newly diagnosed T2DM with hypertriglyceridemia were younger, fatter and had worse lipid profiles, glucose profiles, and high insulin levels than those with normal TG. There is no difference in early phase insulin secretion among groups of newly diagnosed T2DM patients with different TG levels. The basal beta cell function (HOMA-β and MBCI) initially increased along rising TG levels and then decreased as the TG levels rose further. The insulin sensitivity was relatively high in patients with a low level of TG and low with a high level of TG. Hypertriglyceridemia influences clinical characteristics and β cell function of Chinese patients with newly diagnosed T2DM. A better management of dyslipidemia may, to some extent, reduce the effect of lipotoxicity, thereby improving glucose homeostasis in patients with newly diagnosed T2DM.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    This review focuses on the emerging evidence that reactive oxygen species (ROS) derived from glucose metabolism, such as H 2 O 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.

  5. Generation of Functional Beta-Like Cells from Human Exocrine Pancreas.

    Directory of Open Access Journals (Sweden)

    Maria J Lima

    Full Text Available Transcription factor mediated lineage reprogramming of human pancreatic exocrine tissue could conceivably provide an unlimited supply of islets for transplantation in the treatment of diabetes. Exocrine tissue can be efficiently reprogrammed to islet-like cells using a cocktail of transcription factors: Pdx1, Ngn3, MafA and Pax4 in combination with growth factors. We show here that overexpression of exogenous Pax4 in combination with suppression of the endogenous transcription factor ARX considerably enhances the production of functional insulin-secreting β-like cells with concomitant suppression of α-cells. The efficiency was further increased by culture on laminin-coated plates in media containing low glucose concentrations. Immunocytochemistry revealed that reprogrammed cultures were composed of ~45% islet-like clusters comprising >80% monohormonal insulin+ cells. The resultant β-like cells expressed insulin protein levels at ~15-30% of that in adult human islets, efficiently processed proinsulin and packaged insulin into secretory granules, exhibited glucose responsive insulin secretion, and had an immediate and prolonged effect in normalising blood glucose levels upon transplantation into diabetic mice. We estimate that approximately 3 billion of these cells would have an immediate therapeutic effect following engraftment in type 1 diabetes patients and that one pancreas would provide sufficient tissue for numerous transplants.

  6. Valsartan Improves β-Cell Function and Insulin Sensitivity in Subjects With Impaired Glucose Metabolism

    Science.gov (United States)

    van der Zijl, Nynke J.; Moors, Chantalle C.M.; Goossens, Gijs H.; Hermans, Marc M.H.; Blaak, Ellen E.; Diamant, Michaela

    2011-01-01

    OBJECTIVE Recently, the Nateglinide and Valsartan in Impaired Glucose Tolerance Outcomes Research Trial demonstrated that treatment with the angiotensin receptor blocker (ARB) valsartan for 5 years resulted in a relative reduction of 14% in the incidence of type 2 diabetes in subjects with impaired glucose metabolism (IGM). We investigated whether improvements in β-cell function and/or insulin sensitivity underlie these preventive effects of the ARB valsartan in the onset of type 2 diabetes. RESEARCH DESIGN AND METHODS In this randomized controlled, double-blind, two-center study, the effects of 26 weeks of valsartan (320 mg daily; n = 40) or placebo (n = 39) on β-cell function and insulin sensitivity were assessed in subjects with impaired fasting glucose and/or impaired glucose tolerance, using a combined hyperinsulinemic-euglycemic and hyperglycemic clamp with subsequent arginine stimulation and a 2-h 75-g oral glucose tolerance test (OGTT). Treatment effects were analyzed using ANCOVA, adjusting for center, glucometabolic status, and sex. RESULTS Valsartan increased first-phase (P = 0.028) and second-phase (P = 0.002) glucose-stimulated insulin secretion compared with placebo, whereas the enhanced arginine-stimulated insulin secretion was comparable between groups (P = 0.25). In addition, valsartan increased the OGTT-derived insulinogenic index (representing first-phase insulin secretion after an oral glucose load; P = 0.027). Clamp-derived insulin sensitivity was significantly increased with valsartan compared with placebo (P = 0.049). Valsartan treatment significantly decreased systolic and diastolic blood pressure compared with placebo (P valsartan treatment increased glucose-stimulated insulin release and insulin sensitivity in normotensive subjects with IGM. These findings may partly explain the beneficial effects of valsartan in the reduced incidence of type 2 diabetes. PMID:21330640

  7. The disposition index does not reflect β-cell function in IGT subjects treated with pioglitazone.

    Science.gov (United States)

    DeFronzo, Ralph A; Tripathy, Devjit; Abdul-Ghani, Muhammad; Musi, Nicolas; Gastaldelli, Amalia

    2014-10-01

    The insulin secretion/insulin resistance (IR) (disposition) index (ΔI/ΔG ÷ IR, where Δ is change from baseline, I is insulin, and G is glucose) is commonly used as a measure of β-cell function. This relationship is curvilinear and becomes linear when log transformed. ΔI is determined by 2 variables: insulin secretion rate (ISR) and metabolic clearance of insulin. We postulated that the characteristic curvilinear relationship would be lost if Δ plasma C-peptide (ΔCP) (instead of Δ plasma insulin) was plotted against insulin sensitivity. A total of 441 individuals with impaired glucose tolerance (IGT) from ACT NOW received an oral glucose tolerance test and were randomized to pioglitazone or placebo for 2.4 years. Pioglitazone reduced IGT conversion to diabetes by 72% (P < .0001). ΔI/ΔG vs the Matsuda index of insulin sensitivity showed the characteristic curvilinear relationship. However, when ΔCP/ΔG or ΔISR/ΔG was plotted against the Matsuda index, the curvilinear relationship was completely lost. This discordance was explained by 2 distinct physiologic effects that altered plasma insulin response in opposite directions: 1) increased ISR and 2) augmented metabolic clearance of insulin. The net result was a decline in the plasma insulin response to hyperglycemia during the oral glucose tolerance test. These findings demonstrate a physiologic control mechanism wherein the increase in ISR ensures adequate insulin delivery into the portal circulation to suppress hepatic glucose production while delivering a reduced but sufficient amount of insulin to peripheral tissues to maintain the pioglitazone-mediated improvement in insulin sensitivity without excessive hyperinsulinemia. These results demonstrate the validity of the disposition index when relating the plasma insulin response to insulin sensitivity but underscore the pitfall of this index when drawing conclusions about β-cell function, because insulin secretion declined despite an increase in the

  8. Generation of an induced pluripotent stem cell (iPSC line from a patient with maturity-onset diabetes of the young type 3 (MODY3 carrying a hepatocyte nuclear factor 1-alpha (HNF1A mutation

    Directory of Open Access Journals (Sweden)

    Frank Griscelli

    2018-05-01

    Full Text Available Heterozygous non-synonymous (p.S142F mutation in HNF1A leads to maturity-onset diabetes of the young (MODY type 3, which is a subtype of dominant inherited young-onset non-autoimmune diabetes due to the defect of insulin secretion from pancreatic beta cells. We generated induced pluripotent stem cells (iPSCs from a patient with HNF1A p.S142F mutation. Cells from this patient, which were reprogrammed by non-integrative viral transduction had normal karyotype, harboured the HNF1A p.S142F mutation, expressed pluripotency hallmarks.

  9. Polymorphisms within novel risk loci for type 2 diabetes determine beta-cell function.

    Directory of Open Access Journals (Sweden)

    Harald Staiger

    Full Text Available BACKGROUND: Type 2 diabetes arises when insulin resistance-induced compensatory insulin secretion exhausts. Insulin resistance and/or beta-cell dysfunction result from the interaction of environmental factors (high-caloric diet and reduced physical activity with a predisposing polygenic background. Very recently, genetic variations within four novel genetic loci (SLC30A8, HHEX, EXT2, and LOC387761 were reported to be more frequent in subjects with type 2 diabetes than in healthy controls. However, associations of these variations with insulin resistance and/or beta-cell dysfunction were not assessed. METHODOLOGY/PRINCIPAL FINDINGS: By genotyping of 921 metabolically characterized German subjects for the reported candidate single nucleotide polymorphisms (SNPs, we show that the major alleles of the SLC30A8 SNP rs13266634 and the HHEX SNP rs7923837 associate with reduced insulin secretion stimulated by orally or intravenously administered glucose, but not with insulin resistance. In contrast, the other reported type 2 diabetes candidate SNPs within the EXT2 and LOC387761 loci did not associate with insulin resistance or beta-cell dysfunction, respectively. CONCLUSIONS/SIGNIFICANCE: The HHEX and SLC30A8 genes encode for proteins that were shown to be required for organogenesis of the ventral pancreas and for insulin maturation/storage, respectively. Therefore, the major alleles of type 2 diabetes candidate SNPs within these genetic loci represent crucial alleles for beta-cell dysfunction and, thus, might confer increased susceptibility of beta-cells towards adverse environmental factors.

  10. The Role of the Sweet Taste Receptor in Enteroendocrine Cells and Pancreatic β-Cells

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    Itaru Kojima

    2011-10-01

    Full Text Available The sweet taste receptor is expressed in taste cells located in taste buds of the tongue. This receptor senses sweet substances in the oral cavity, activates taste cells, and transmits the taste signals to adjacent neurons. The sweet taste receptor is a heterodimer of two G protein-coupled receptors, T1R2 and T1R3. Recent studies have shown that this receptor is also expressed in the extragustatory system, including the gastrointestinal tract, pancreatic β-cells, and glucose-responsive neurons in the brain. In the intestine, the sweet taste receptor regulates secretion of incretin hormones and glucose uptake from the lumen. In β-cells, activation of the sweet taste receptor leads to stimulation of insulin secretion. Collectively, the sweet taste receptor plays an important role in recognition and metabolism of energy sources in the body.

  11. Beneficial Effect of Jojoba Seed Extracts on Hyperglycemia-Induced Oxidative Stress in RINm5f Beta Cells

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    Sahla Belhadj

    2018-03-01

    Full Text Available Hyperglycemia occurs during diabetes and insulin resistance. It causes oxidative stress by increasing reactive oxygen species (ROS levels, leading to cellular damage. Polyphenols play a central role in defense against oxidative stress. In our study, we investigated the antioxidant properties of simmondsin, a pure molecule present in jojoba seeds, and of the aqueous extract of jojoba seeds on fructose-induced oxidative stress in RINm5f beta cells. The exposure of RINm5f beta cells to fructose triggered the loss of cell viability (−48%, p < 0.001 and disruption of insulin secretion (p < 0.001 associated with of reactive oxygen species (ROS production and a modulation of pro-oxidant and antioxidant signaling pathway. Cell pre-treatments with extracts considerably increased cell viability (+86% p < 0.001 for simmondsin and +74% (p < 0.001 for aqueous extract and insulin secretion. The extracts also markedly decreased ROS (−69% (p < 0.001 for simmondsin and −59% (p < 0.001 for aqueous extract and caspase-3 activation and improved antioxidant defense, inhibiting p22phox and increasing nuclear factor (erythroid-derived 2-like 2 (Nrf2 levels (+70%, p < 0.001 for aqueous extract. Simmondsin had no impact on Nrf2 levels. The richness and diversity of molecules present in jojoba seed extract makes jojoba a powerful agent to prevent the destruction of RINm5f beta cells induced by hyperglycemia.

  12. Observation on beta-cell function in patients with type 2 diabetic patients

    International Nuclear Information System (INIS)

    Liao Yu; Chen Xingwen; Jiang Feilong

    2009-01-01

    Objective: o study the pancreatic islets β-cell function in type 2 diabitic patients through the changes of parameters of β-cell function and the effects of plasma glucose levels on insulin secretion function in subjects with different blood glucos levels. ethods:A total of 172 patients with type 2 diabetes and 30 controls were enrolled to take oral 75g glucose tolerance test and insulin releasing test (TRT). These patients were of four groups based upon their fasting insulin levels group A fasting low insulin ( 30 /ΔG 30 ). Basic insulin secretion index (HOMA β) and modified β-cell function index (MBCI) were calculated. Results:Insulin levels in group A, B, C, D were significantly different from those of controls (P 30 /ΔG 30 ) between group A and group B. There were significant difference in MBCI between group C and group D. There was significant difference in HOMA β between group A and group B as well as between group C and group D. The ΔI 30 /ΔG 30 was positively correlated with HOMA β in all groups however, ΔI 30 /ΔG 30 was not correlated with BCI. Conclusion:ΔI 30 /ΔG 30 , MBCI and HOMA β may be used to evaluate β-cell function. Both the insulin release test and glucose tolerance test should be performed before treatment in patients with type 2 diabetes mellitus. (authors)

  13. Visualizing pancreatic {beta}-cell mass with [{sup 11}C]DTBZ

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Norman Ray [Department of Radiology, Columbia University Medical School, New York, NY 10032 (United States); Souza, Fabiola [Department of Surgery, Columbia University Medical School, New York, NY 10032 (United States); Witkowski, Piotr [Department of Medicine, Columbia University Medical School, New York, NY 10032 (United States); Maffei, Antonella [Institute of Genetics and Biophysics ' Adriano Buzzati-Traverso' , CNR, Naples 80131 (Italy); Raffo, Anthony [Department of Surgery, Columbia University Medical School, New York, NY 10032 (United States); Herron, Alan [Center for Comparative Medicine and The Department of Pathology, Baylor College of Medicine, Houston, TX 77030 (United States); Kilbourn, Michael [Department of Radiology, University of Michigan, Ann Arbor, MI 48109-0638 (United States); Jurewicz, Agata [Department of Radiology, Columbia University Medical School, New York, NY 10032 (United States); Herold, Kevan [Department of Surgery, Columbia University Medical School, New York, NY 10032 (United States); Liu, Eric [Diabetes Branch, NIDDK, National Institutes of Health, Bethesda, MD 20854 (United States); Hardy, Mark Adam [Department of Medicine, Columbia University Medical School, New York, NY 10032 (United States); Van Heertum, Ronald [Department of Radiology, Columbia University Medical School, New York, NY 10032 (United States); Harris, Paul Emerson [Department of Surgery, Columbia University Medical School, New York, NY 10032 (United States)]. E-mail: peh1@columbia.edu

    2006-10-15

    {beta}-Cell mass (BCM) influences the total amount of insulin secreted, varies by individual and by the degree of insulin resistance, and is affected by physiologic and pathologic conditions. The islets of Langerhans, however, appear to have a reserve capacity of insulin secretion and, overall, assessments of insulin and blood glucose levels remain poor measures of BCM, {beta}-cell function and progression of diabetes. Thus, novel noninvasive determinations of BCM are needed to provide a quantitative endpoint for novel therapies of diabetes, islet regeneration and transplantation. Built on previous gene expression studies, we tested the hypothesis that the targeting of vesicular monoamine transporter 2 (VMAT2), which is expressed by {beta} cells, with [{sup 11}C]dihydrotetrabenazine ([{sup 11}C]DTBZ), a radioligand specific for VMAT2, and the use of positron emission tomography (PET) can provide a measure of BCM. In this report, we demonstrate decreased radioligand uptake within the pancreas of Lewis rats with streptozotocin-induced diabetes relative to their euglycemic historical controls. These studies suggest that quantitation of VMAT2 expression in {beta} cells with the use of [{sup 11}C]DTBZ and PET represents a method for noninvasive longitudinal estimates of changes in BCM that may be useful in the study and treatment of diabetes.

  14. Visualizing pancreatic β-cell mass with [11C]DTBZ

    International Nuclear Information System (INIS)

    Simpson, Norman Ray; Souza, Fabiola; Witkowski, Piotr; Maffei, Antonella; Raffo, Anthony; Herron, Alan; Kilbourn, Michael; Jurewicz, Agata; Herold, Kevan; Liu, Eric; Hardy, Mark Adam; Van Heertum, Ronald; Harris, Paul Emerson

    2006-01-01

    β-Cell mass (BCM) influences the total amount of insulin secreted, varies by individual and by the degree of insulin resistance, and is affected by physiologic and pathologic conditions. The islets of Langerhans, however, appear to have a reserve capacity of insulin secretion and, overall, assessments of insulin and blood glucose levels remain poor measures of BCM, β-cell function and progression of diabetes. Thus, novel noninvasive determinations of BCM are needed to provide a quantitative endpoint for novel therapies of diabetes, islet regeneration and transplantation. Built on previous gene expression studies, we tested the hypothesis that the targeting of vesicular monoamine transporter 2 (VMAT2), which is expressed by β cells, with [ 11 C]dihydrotetrabenazine ([ 11 C]DTBZ), a radioligand specific for VMAT2, and the use of positron emission tomography (PET) can provide a measure of BCM. In this report, we demonstrate decreased radioligand uptake within the pancreas of Lewis rats with streptozotocin-induced diabetes relative to their euglycemic historical controls. These studies suggest that quantitation of VMAT2 expression in β cells with the use of [ 11 C]DTBZ and PET represents a method for noninvasive longitudinal estimates of changes in BCM that may be useful in the study and treatment of diabetes

  15. Microculture system for studying monolayers of functional beta-cells.

    Science.gov (United States)

    Dobersen, M J; Scharff, J E; Notkins, A L

    1980-04-01

    A method is described for growing monolayers of newborn rat beta-cells in microculture trays. After disruption of the pancreas with collagenase, islets were isolated by Ficoll density gradient centrifugation, trypsinized to obtain individual cells, and plated in 96-well tissue culture trays. The cells were incubated for the first 3 days in growth medium containing 0.1 mM 3-isobutyl-1-methylxanthine to promote monolayer formation. The cultures could be maintained in a functional state, as defined by their responsiveness to known modulators of insulin secretion, for at least 2 weeks. As few as 1 X 10(3) islet cells/well gave results that were reproducible within +/- 10%. It is suggested that the microculture system for islet cells might prove to be a rapid and reproducible screening technique for studying drugs, viruses, or other agents that affect beta-cell function.

  16. Adipose Tissue-Derived Mesenchymal Stem Cells Exert In Vitro Immunomodulatory and Beta Cell Protective Functions in Streptozotocin-Induced Diabetic Mice Model

    Directory of Open Access Journals (Sweden)

    Hossein Rahavi

    2015-01-01

    Full Text Available Regenerative and immunomodulatory properties of mesenchymal stem cells (MSCs might be applied for type 1 diabetes mellitus (T1DM treatment. Thus, we proposed in vitro assessment of adipose tissue-derived MSCs (AT-MSCs immunomodulation on autoimmune response along with beta cell protection in streptozotocin- (STZ- induced diabetic C57BL/6 mice model. MSCs were extracted from abdominal adipose tissue of normal mice and cultured to proliferate. Diabetic mice were prepared by administration of multiple low-doses of streptozotocin. Pancreatic islets were isolated from normal mice and splenocytes prepared from normal and diabetic mice. Proliferation, cytokine production, and insulin secretion assays were performed in coculture experiments. AT-MSCs inhibited splenocytes proliferative response to specific (islet lysate and nonspecific (PHA triggers in a dose-dependent manner (P<0.05. Decreased production of proinflammatory cytokines, such as IFN-γ, IL-2, and IL-17, and increased secretion of regulatory cytokines such as TGF-β, IL-4, IL-10, and IL-13 by stimulated splenocytes were also shown in response to islet lysate or PHA stimulants (P<0.05. Finally, we demonstrated that AT-MSCs could effectively sustain viability as well as insulin secretion potential of pancreatic islets in the presence of reactive splenocytes (P<0.05. In conclusion, it seems that MSCs may provide a new horizon for T1DM cell therapy and islet transplantation in the future.

  17. Carriers of loss-of-function mutations in EXT display impaired pancreatic beta-cell reserve due to smaller pancreas volume.

    Directory of Open Access Journals (Sweden)

    Sophie J Bernelot Moens

    Full Text Available Exotosin (EXT proteins are involved in the chain elongation step of heparan sulfate (HS biosynthesis, which is intricately involved in organ development. Loss of function mutations (LOF in EXT1 and EXT2 result in hereditary exostoses (HME. Interestingly, HS plays a role in pancreas development and beta-cell function, and genetic variations in EXT2 are associated with an increased risk for type 2 diabetes mellitus. We hypothesized that loss of function of EXT1 or EXT2 in subjects with hereditary multiple exostoses (HME affects pancreatic insulin secretion capacity and development. We performed an oral glucose tolerance test (OGTT followed by hyperglycemic clamps to investigate first-phase glucose-stimulated insulin secretion (GSIS in HME patients and age and gender matched non-affected relatives. Pancreas volume was assessed with magnetic resonance imaging (MRI. OGTT did not reveal significant differences in glucose disposal, but there was a markedly lower GSIS in HME subjects during hyperglycemic clamp (iAUC HME: 0.72 [0.46-1.16] vs. controls 1.53 [0.69-3.36] nmol·l-1·min-1, p<0.05. Maximal insulin response following arginine challenge was also significantly attenuated (iAUC HME: 7.14 [4.22-10.5] vs. controls 10.2 [7.91-12.70] nmol·l-1·min-1 p<0.05, indicative of an impaired beta-cell reserve. MRI revealed a significantly smaller pancreatic volume in HME subjects (HME: 72.0±15.8 vs. controls 96.5±26.0 cm3 p = 0.04. In conclusion, loss of function of EXT proteins may affect beta-cell mass and insulin secretion capacity in humans, and render subjects at a higher risk of developing type 2 diabetes when exposed to environmental risk factors.

  18. Genetically Engineered Islets and Alternative Sources of Insulin-Producing Cells for Treating Autoimmune Diabetes: Quo Vadis?

    Directory of Open Access Journals (Sweden)

    Feng-Cheng Chou

    2012-01-01

    Full Text Available Islet transplantation is a promising therapy for patients with type 1 diabetes that can provide moment-to-moment metabolic control of glucose and allow them to achieve insulin independence. However, two major problems need to be overcome: (1 detrimental immune responses, including inflammation induced by the islet isolation/transplantation procedure, recurrence autoimmunity, and allorejection, can cause graft loss and (2 inadequate numbers of organ donors. Several gene therapy approaches and pharmaceutical treatments have been demonstrated to prolong the survival of pancreatic islet grafts in animal models; however, the clinical applications need to be investigated further. In addition, for an alternative source of pancreatic β-cell replacement therapy, the ex vivo generation of insulin-secreting cells from diverse origins of stem/progenitor cells has become an attractive option in regenerative medicine. This paper focuses on the genetic manipulation of islets during transplantation therapy and summarizes current strategies to obtain functional insulin-secreting cells from stem/progenitor cells.

  19. Roles of HNF1α and HNF4α in pancreatic β-cells: lessons from a monogenic form of diabetes (MODY).

    Science.gov (United States)

    Yamagata, Kazuya

    2014-01-01

    Mutations in the genes encoding hepatocyte nuclear factor (HNF)1α and HNF4α cause a monogenic form of diabetes mellitus known as maturity-onset diabetes of the young (MODY). The primary cause of MODY is an impairment of glucose-stimulated insulin secretion by pancreatic β-cells, indicating the important roles of HNF1α and HNF4α in β-cells. Large-scale genetic studies have clarified that the common variants of HNF1α and HNF4α genes are also associated with type 2 diabetes, suggesting that they are involved in the pathogenesis of both diseases. Recent experimental studies revealed that HNF1α controls both β-cell function and growth by regulating target genes such as glucose transporter 2, pyruvate kinase, collectrin, hepatocyte growth factor activator, and HNF4α. In contrast, HNF4α mainly regulates the function of β-cells. Although direct target genes of HNF4α in β-cells are largely unknown, we recently identified Anks4b as a novel target of HNF4α that regulates β-cell susceptibility to endoplasmic reticulum stress. Studies of MODY have led to a better understanding of the molecular mechanism of glucose-stimulated insulin secretion by pancreatic β-cells. © 2014 Elsevier Inc. All rights reserved.

  20. Genetic evidence that HNF-1alpha-dependent transcriptional control of HNF-4alpha is essential for human pancreatic beta cell function

    DEFF Research Database (Denmark)

    Hansen, Sara K; Párrizas, Marcelina; Jensen, Maria L

    2002-01-01

    Mutations in the genes encoding hepatocyte nuclear factor 4alpha (HNF-4alpha) and HNF-1alpha impair insulin secretion and cause maturity onset diabetes of the young (MODY). HNF-4alpha is known to be an essential positive regulator of HNF-1alpha. More recent data demonstrates that HNF-4alpha...... in human islets and exocrine cells is primarily mediated by the P2 promoter. Furthermore, we describe a G --> A mutation in a conserved nucleotide position of the HNF-1alpha binding site of the P2 promoter, which cosegregates with MODY. The mutation results in decreased affinity for HNF-1alpha...

  1. Serotonin- and Dopamine-Related Gene Expression in db/db Mice Islets and in MIN6 β-Cells Treated with Palmitate and Oleate

    Directory of Open Access Journals (Sweden)

    L. R. Cataldo

    2016-01-01

    Full Text Available High circulating nonesterified fatty acids (NEFAs concentration, often reported in diabetes, leads to impaired glucose-stimulated insulin secretion (GSIS through not yet well-defined mechanisms. Serotonin and dopamine might contribute to NEFA-dependent β-cell dysfunction, since extracellular signal of these monoamines decreases GSIS. Moreover, palmitate-treated β-cells may enhance the expression of the serotonin receptor Htr2c, affecting insulin secretion. Additionally, the expression of monoamine-oxidase type B (Maob seems to be lower in islets from humans and mice with diabetes compared to nondiabetic islets, which may lead to increased monoamine concentrations. We assessed the expression of serotonin- and dopamine-related genes in islets from db/db and wild-type (WT mice. In addition, the effect of palmitate and oleate on the expression of such genes, 5HT content, and GSIS in MIN6 β-cell was determined. Lower Maob expression was found in islets from db/db versus WT mice and in MIN6 β-cells in response to palmitate and oleate treatment compared to vehicle. Reduced 5HT content and impaired GSIS in response to palmitate (−25%; p<0.0001 and oleate (−43%; p<0.0001 were detected in MIN6 β-cells. In conclusion, known defects of GSIS in islets from db/db mice and MIN6 β-cells treated with NEFAs are accompanied by reduced Maob expression and reduced 5HT content.

  2. In Vitro Effect of Fatty Acids Identified in the Plasma of Obese Adolescents on the Function of Pancreatic β-Cells

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    Claudia Velasquez

    2017-05-01

    Full Text Available BackgroundThe increase in circulating free fatty acid (FFA levels is a major factor that induces malfunction in pancreatic β-cells. We evaluated the effect of FFAs reconstituted according to the profile of circulating fatty acids found in obese adolescents on the viability and function of the murine insulinoma cell line (mouse insulinoma [MIN6].MethodsFrom fatty acids obtained commercially, plasma-FFA profiles of three different youth populations were reconstituted: obese with metabolic syndrome; obese without metabolic syndrome; and normal weight without metabolic syndrome. MIN6 cells were treated for 24 or 48 hours with the three FFA profiles, and glucose-stimulated insulin secretion, cell viability, mitochondrial function and antioxidant activity were evaluated.ResultsThe high FFA content and high polyunsaturated ω6/ω3 ratio, present in plasma of obese adolescents with metabolic syndrome had a toxic effect on MIN6 cell viability and function, increasing oxidative stress and decreasing glucose-dependent insulin secretion.ConclusionThese results could help to guide nutritional management of obese young individuals, encouraging the increase of ω-3-rich food consumption in order to reduce the likelihood of deterioration of β-cells and the possible development of type 2 diabetes mellitus.

  3. Casein Hydrolysate with Glycemic Control Properties: Evidence from Cells, Animal Models, and Humans.

    Science.gov (United States)

    Drummond, Elaine; Flynn, Sarah; Whelan, Helena; Nongonierma, Alice B; Holton, Thérèse A; Robinson, Aisling; Egan, Thelma; Cagney, Gerard; Shields, Denis C; Gibney, Eileen R; Newsholme, Philip; Gaudel, Celine; Jacquier, Jean-Christophe; Noronha, Nessa; FitzGerald, Richard J; Brennan, Lorraine

    2018-05-02

    Evidence exists to support the role of dairy derived proteins whey and casein in glycemic management. The objective of the present study was to use a cell screening method to identify a suitable casein hydrolysate and to examine its ability to impact glycemia related parameters in an animal model and in humans. Following screening for the ability to stimulate insulin secretion in pancreatic beta cells, a casein hydrolysate was selected and further studied in the ob/ob mouse model. An acute postprandial study was performed in 62 overweight and obese adults. Acute and long-term supplementation with the casein hydrolysate in in vivo studies in mice revealed a glucose lowering effect and a lipid reducing effect of the hydrolysate (43% reduction in overall liver fat). The postprandial human study revealed a significant increase in insulin secretion ( p = 0.04) concomitant with a reduction in glucose ( p = 0.03). The area under the curve for the change in glucose decreased from 181.84 ± 14.6 to 153.87 ± 13.02 ( p = 0.009). Overall, the data supports further work on the hydrolysate to develop into a functional food product.

  4. Generation of glucose-responsive, insulin-producing cells from human umbilical cord blood-derived mesenchymal stem cells.

    Science.gov (United States)

    Prabakar, Kamalaveni R; Domínguez-Bendala, Juan; Molano, R Damaris; Pileggi, Antonello; Villate, Susana; Ricordi, Camillo; Inverardi, Luca

    2012-01-01

    We sought to assess the potential of human cord blood-derived mesenchymal stem cells (CB-MSCs) to derive insulin-producing, glucose-responsive cells. We show here that differentiation protocols based on stepwise culture conditions initially described for human embryonic stem cells (hESCs) lead to differentiation of cord blood-derived precursors towards a pancreatic endocrine phenotype, as assessed by marker expression and in vitro glucose-regulated insulin secretion. Transplantation of these cells in immune-deficient animals shows human C-peptide production in response to a glucose challenge. These data suggest that human cord blood may be a promising source for regenerative medicine approaches for the treatment of diabetes mellitus.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Jun; Jiang, Li; Lue, Qingguo; Ke, Linqiu [Department of Endocrinology, West China Hospital of Sichuan University, 37 Guoxue Lane, Chengdu, Sichuan 610041 (China); Li, Xiaoyu [State Key Laboratory of Oral Diseases, Sichuan University, No. 14, 3rd Section, Renmin South Road, Chengdu, Sichuan 610041 (China); Tong, Nanwei, E-mail: buddyjun@hotmail.com [Department of Endocrinology, West China Hospital of Sichuan University, 37 Guoxue Lane, Chengdu, Sichuan 610041 (China)

    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.

  6. In vivo and in vitro evaluation of the effects of Urtica dioica and swimming activity on diabetic factors and pancreatic beta cells.

    Science.gov (United States)

    Ranjbari, Abbas; Azarbayjani, Mohammad Ali; Yusof, Ashril; Halim Mokhtar, Abdul; Akbarzadeh, Samad; Ibrahim, Mohamed Yousif; Tarverdizadeh, Bahman; Farzadinia, Parviz; Hajiaghaee, Reza; Dehghan, Firouzeh

    2016-03-15

    Urtica dioica (UD) has been identified as a traditional herbal medicine. This study aimed to investigate the effect of UD extract and swimming activity on diabetic parameters through in vivo and in vitro experiments. Adult WKY male rats were randomly distributed in nine groups: intact control, diabetic control, diabetic + 625 mg/kg, 1.25 g/kg UD, diabetic + 100 mg/kg Metformin, diabetic + swimming, diabetic + swimming 625 mg/kg, 1.25 g/kg UD, and diabetic +100 mg/kg Metformin + swimming. The hearts of the animals were punctured, and blood samples were collected for biochemical analysis. The entire pancreas was exposed for histologic examination. The effect of UD on insulin secretion by RIN-5F cells in 6.25 or 12.5 mM glucose dose was examined. Glucose uptake by cultured L6 myotubes was determined. The serum glucose concentration decreased, the insulin resistance and insulin sensitivity significantly increased in treated groups. These changes were more pronounced in the group that received UD extract and swimming training. Regeneration and less beta cell damage of Langerhans islets were observed in the treated groups. UD treatment increased insulin secretion in the RIN-5F cells and glucose uptake in the L6 myotubes cells. Swimming exercises accompanied by consuming UD aqueous extracts effectively improved diabetic parameters, repaired pancreatic tissues in streptozotocin-induced diabetics in vivo, and increased glucose uptake or insulin in UD-treated cells in vitro.

  7. β-Cell Replacement in Mice Using Human Type 1 Diabetes Nuclear Transfer Embryonic Stem Cells.

    Science.gov (United States)

    Sui, Lina; Danzl, Nichole; Campbell, Sean R; Viola, Ryan; Williams, Damian; Xing, Yuan; Wang, Yong; Phillips, Neil; Poffenberger, Greg; Johannesson, Bjarki; Oberholzer, Jose; Powers, Alvin C; Leibel, Rudolph L; Chen, Xiaojuan; Sykes, Megan; Egli, Dieter

    2018-01-01

    β-Cells derived from stem cells hold great promise for cell replacement therapy for diabetes. Here we examine the ability of nuclear transfer embryonic stem cells (NT-ESs) derived from a patient with type 1 diabetes to differentiate into β-cells and provide a source of autologous islets for cell replacement. NT-ESs differentiate in vitro with an average efficiency of 55% into C-peptide-positive cells, expressing markers of mature β-cells, including MAFA and NKX6.1. Upon transplantation in immunodeficient mice, grafted cells form vascularized islet-like structures containing MAFA/C-peptide-positive cells. These β-cells adapt insulin secretion to ambient metabolite status and show normal insulin processing. Importantly, NT-ES-β-cells maintain normal blood glucose levels after ablation of the mouse endogenous β-cells. Cystic structures, but no teratomas, were observed in NT-ES-β-cell grafts. Isogenic induced pluripotent stem cell lines showed greater variability in β-cell differentiation. Even though different methods of somatic cell reprogramming result in stem cell lines that are molecularly indistinguishable, full differentiation competence is more common in ES cell lines than in induced pluripotent stem cell lines. These results demonstrate the suitability of NT-ES-β-cells for cell replacement for type 1 diabetes and provide proof of principle for therapeutic cloning combined with cell therapy. © 2017 by the American Diabetes Association.

  8. Transcriptomic profiling of pancreatic alpha, beta and delta cell populations identifies delta cells as a principal target for ghrelin in mouse islets

    DEFF Research Database (Denmark)

    Adriaenssens, Alice E; Svendsen, Berit; Lam, Brian Y H

    2016-01-01

    cytometry and analysed by RNA sequencing. The role of the ghrelin receptor was validated by imaging delta cell calcium concentrations using islets with delta cell restricted expression of the calcium reporter GCaMP3, and in perfused mouse pancreases. RESULTS: A database was constructed of all genes...... expressed in alpha, beta and delta cells. The gene encoding the ghrelin receptor, Ghsr, was highlighted as being highly expressed and enriched in delta cells. Activation of the ghrelin receptor raised cytosolic calcium levels in primary pancreatic delta