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Sample records for rat pancreatic beta-cells

  1. 4-Phenylbutyric Acid Attenuates Pancreatic Beta-Cell Injury in Rats with Experimental Severe Acute Pancreatitis

    PubMed Central

    Guo, Wen-yi; Zhao, Liang; Xiang, Ming-wei; Mei, Fang-chao; Abliz, Ablikim; Hu, Peng; Deng, Wen-hong; Yu, Jia

    2016-01-01

    Endoplasmic reticulum (ER) stress is a particular process with an imbalance of homeostasis, which plays an important role in pancreatitis, but little is known about how ER stress is implicated in severe acute pancreatitis (SAP) induced pancreatic beta-cell injury. To investigate the effect of 4-phenylbutyric acid (4-PBA) on the beta-cell injury following SAP and the underlying mechanism, twenty-four Sprague-Dawley rats were randomly divided into sham-operation (SO) group, SAP model group, and 4-PBA treatment group. SAP model was induced by infusion of 5% sodium taurocholate into the biliopancreatic duct. 4-PBA or normal saline was injected intraperitoneally for 3 days in respective group before successful modeling. Results showed that 4-PBA attenuated the following: (1) pancreas and islet pathological injuries, (2) serum TNF-α and IL-1β, (3) serum insulin and glucose, (4) beta-cell ultrastructural changes, (5) ER stress markers (BiP, ORP150, and CHOP), Caspase-3, and insulin expression in islet. These results suggested that 4-PBA mitigates pancreatic beta-cell injury and endocrine disorder in SAP, presumably because of its role in inhibiting excessive endoplasmic reticulum stress. This may serve as a new therapeutic target for reducing pancreatic beta-cell injury and endocrine disorder in SAP upon 4-PBA treatment. PMID:27656209

  2. [The effect of ionizing radiation on the resistance of rat pancreatic beta cells to streptozotocin].

    PubMed

    Gatsko, G G; Brilevskaia, S I

    1993-01-01

    The effect of subliminal streptozotocin doses of rat pancreas cells was studied 1 and 3 months after 1-Gy gamma irradiation. Streptozotocin injected to irradiated animals caused a drastic decrease in beta-cell function which was manifested by hyperglycemia and less intensive secretion and lesser content of insulin in isolated pancreatic islands, as compared to control.

  3. Dopamine modulates insulin release and is involved in the survival of rat pancreatic beta cells.

    PubMed

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

    2015-01-01

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

  4. Effect of phensuccinal on pancreatic beta-cells in rats with neonatally induced streptozotocin diabetes mellitus.

    PubMed

    Gorbenko, N I; Poltorak, V V; Gladkikh, A I; Ivanova, O V

    2001-07-01

    The effect of phensuccinal, a low-toxic succinic acid derivative, on the function of pancreatic beta-cells in the evolution of absolute insulin insufficiency was studied in rats with neonatally induced streptozotocin diabetes mellitus. Phensuccinal (25 mg/kg body weight) prevented disorders in the secretory response of beta-cells to glucose load at all stages of the study (2, 5, and 14 days after diabetes induction). This effect was realized via stimulation of the regenerative processes in the insulin-producing system of the pancreas and activation of the antioxidant system in diabetic animals.

  5. Impaired pancreatic beta cell function in the fetal GK rat. Impact of diabetic inheritance.

    PubMed Central

    Serradas, P; Gangnerau, M N; Giroix, M H; Saulnier, C; Portha, B

    1998-01-01

    The Goto-Kakisaki (GK) rat is a genetic model of non-insulin-dependent diabetes. At 21.5 d of age we found that GK fetuses had an increased plasma glucose concentration, a decreased plasma insulin level, and a reduced pancreatic beta cell mass. To investigate the beta cell function during fetal life we used a hyperglycemic clamp protocol applied to the mothers, which allowed us to obtain a steady-state hyperglycemia in the corresponding fetuses. At variance, with Wistar (W) fetuses, plasma insulin concentration in GK fetuses did not rise in response to hyperglycemia. In contrast, GK fetal pancreas released insulin in response to glucose in vitro to the same extent as W fetal pancreas. Such a discrepancy between the in vivo and in vitro results suggests that the lack of pancreatic reactivity to glucose as seen in vivo is extrinsic to the fetal GK beta cell. Finally, the importance of gestational hyperglycemia was investigated by performing crosses between GK and W rats. Fetuses issued from crosses between W mother and GK father or GK mother and W father had a beta cell mass close to normal values and were still able to increase their plasma insulin levels in response to hyperglycemia in vivo. Our data suggest that hyperglycemia in utero does not influence the severity of the decrease of the beta cell mass or the lack of the insulin secretory response to glucose in the fetal GK rat. Moreover they indicate that conjunction of GK genes originating from both parents is necessary in order for these defects to be fully expressed. PMID:9466985

  6. Regeneration of pancreatic beta cells.

    PubMed

    Jun, Hee-Sook

    2008-05-01

    Diabetes mellitus results from inadequate mass of insulin-producing pancreatic beta cells. Type 1 diabetes is characterized by absolute loss of beta cells due to autoimmune-mediated destruction. Type 2 diabetes is characterized by relative deficiency of beta cells due to lack of compensation for insulin resistance. Restoration of deficient beta cell mass by transplantation from exogenous sources or by endogenous regeneration of insulin-producing cells would be therapeutic options. Mature beta cells have an ability to proliferate; however, it has been shown to be difficult to expand adult beta cells in vitro. Alternatively, regeneration of beta cells from embryonic and adult stem cells and pancreatic progenitor cells is an attractive method to restore islet cell mass. With information obtained from the biology of pancreatic development, direct differentiation of stem and progenitor cells toward a pancreatic beta cell phenotype has been tried using various strategies, including forced expression of beta cell-specific transcription factors. Further research is required to understand how endogenous beta cells differentiate and to develop methods to regenerate beta cells for clinically applicable therapies for diabetes.

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

    PubMed

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

    2015-11-01

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

  8. Protein Synthesis in Pancreatic Beta Cells of the Normal and Diabetic Egyptian Sand Rat (Psammomys obesus)

    PubMed Central

    Molleson, Ann L.; Moses, Montrose J.; Hackel, Donald B.

    1973-01-01

    The pattern of protein synthesis was studied in the pancreatic beta cells of the Egyptian sand rat (Psammomys obesus). When fed a standard Purina Laboratory Chow diet instead of a leafy vegetable diet, these animals develop the characteristic signs of diabetes mellitus. Tritiated leucine was injected intravenously into pairs of sand rats (one on a vegetable diet and one on a Purina Laboratory Chow diet). Two pairs of animals were sacrificed at 5-, 20- and 60-minute intervals, and pancreatic tissue was studied by electron microscopic autoradiography. At 5 minutes, the relative grain density was greatest over the rough endoplasmic reticulum; at 20 minutes it was greatest over the Golgi complex and at 60 minutes, over the granules. There were no statistically significant differences in the relative grain densities over the rough endoplasmic reticulum, over the Golgi complex or over the secretion granules between the sand rats on the vegetable diet and Chow diet. These results show that in the early phase of the development of diabetes mellitus, the pattern of protein synthesis in the beta cells of the normal and diabetic sand rat compares with that of other endocrine glands. The tritiated leucine was apparently incorporated into the newly synthesized secretory product in the rough endoplasmic reticulum during the first 5 minutes. The formed product migrated to the Golgi complex at 20 minutes, and at 1 hour was seen mainly over the light granules. In addition, there was no obvious difference in this pattern of protein synthesis between the normal and diabetic sand rats. This suggests that the secretory product, considered to be mainly insulin, is produced in the usual or in increased amounts, but it is not fully utilized by the diabetic animal and remains in circulation, thus increasing the plasma insulin level. ImagesFig 1Fig 2Fig 3Fig 4Fig 5Fig 6 PMID:4586126

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

    NASA Astrophysics Data System (ADS)

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

    1990-09-01

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

  10. PARP-1 and YY1 are important novel regulators of CXCL12 gene transcription in rat pancreatic beta cells.

    PubMed

    Marković, Jelena; Grdović, Nevena; Dinić, Svetlana; Karan-Djurašević, Teodora; Uskoković, Aleksandra; Arambašić, Jelena; Mihailović, Mirjana; Pavlović, Sonja; Poznanović, Goran; Vidaković, Melita

    2013-01-01

    Despite significant progress, the molecular mechanisms responsible for pancreatic beta cell depletion and development of diabetes remain poorly defined. At present, there is no preventive measure against diabetes. The positive impact of CXCL12 expression on the pancreatic beta cell prosurvival phenotype initiated this study. Our aim was to provide novel insight into the regulation of rat CXCL12 gene (Cxcl12) transcription. The roles of poly(ADP-ribose) polymerase-1 (PARP-1) and transcription factor Yin Yang 1 (YY1) in Cxcl12 transcription were studied by examining their in vitro and in vivo binding affinities for the Cxcl12 promoter in a pancreatic beta cell line by the electrophoretic mobility shift assay and chromatin immunoprecipitation. The regulatory activities of PARP-1 and YY1 were assessed in transfection experiments using a reporter vector with a Cxcl12 promoter sequence driving luciferase gene expression. Experimental evidence for PARP-1 and YY1 revealed their trans-acting potential, wherein PARP-1 displayed an inhibitory, and YY1 a strong activating effect on Cxcl12 transcription. Streptozotocin (STZ)-induced general toxicity in pancreatic beta cells was followed by changes in Cxcl12 promoter regulation. PARP-1 binding to the Cxcl12 promoter during basal and in STZ-compromised conditions led us to conclude that PARP-1 regulates constitutive Cxcl12 expression. During the early stage of oxidative stress, YY1 exhibited less affinity toward the Cxcl12 promoter while PARP-1 displayed strong binding. These interactions were accompanied by Cxcl12 downregulation. In the later stages of oxidative stress and intensive pancreatic beta cell injury, YY1 was highly expressed and firmly bound to Cxcl12 promoter in contrast to PARP-1. These interactions resulted in higher Cxcl12 expression. The observed ability of PARP-1 to downregulate, and of YY1 to upregulate Cxcl12 promoter activity anticipates corresponding effects in the natural context where the functional

  11. Involvement of the autonomic nervous system in the in vivo memory to glucose of pancreatic beta cell in rats.

    PubMed Central

    N'Guyen, J M; Magnan, C; Laury, M C; Thibault, C; Leveteau, J; Gilbert, M; Pénicaud, L; Ktorza, A

    1994-01-01

    The fact that the potentiating effect of prolonged hyperglycemia on the subsequent insulin secretion is observed in vivo but not in vitro suggests the involvement of extrapancreatic factors in the in vivo memory of pancreatic beta cells to glucose. We have investigated the possible role of the autonomic nervous system. Rats were made hyperglycemic by a 48-h infusion with glucose (HG rats). At the end of glucose infusion as well as 6 h postinfusion, both parasympathetic and sympathetic nerve activities were profoundly altered: parasympathetic and sympathetic activities, assessed by the firing rate either of the thoracic vagus nerve or the superior cervical ganglion, were dramatically increased and decreased, respectively. Moreover, 6 h after the end of glucose infusion, insulin secretion in response to a glucose load was dramatically increased in HG rats compared to controls. To determine whether these changes could be responsible for the increased sensitivity of the beta cell to glucose, insulin release in response to glucose was measured in HG and control rats, either under subdiaphragmatic vagotomy or after administration of the alpha 2A-adrenergic agonist oxymetazoline. Both treatments partially abolished the hyperresponsiveness of the beta cell to glucose in HG rats. Therefore chronic hyperglycemia brings about changes in the activity of the autonomic nervous system, which in turn are responsible, at least in part, for the generation of enhanced beta cell responsiveness to glucose in vivo. PMID:7929821

  12. Major histocompatibility complex gene product expression on pancreatic beta cells in acutely diabetic BB rats.

    PubMed Central

    Issa-Chergui, B.; Yale, J. F.; Vigeant, C.; Seemayer, T. A.

    1988-01-01

    Type I diabetes mellitus was induced in young, diabetes-prone BB rats by the passive transfer of concanavalin A-activated T lymphocytes from the spleens of acutely diabetic BB rats. The pancreas of the recipients was examined 1-2 days after the onset of glycosuria by immunocytochemistry by means of monoclonal antibodies for determining whether 1) Class I and/or II major histocompatibility gene complex (MHC) products were expressed on beta cells and 2) the mononuclear cell infiltrates were represented by T cells. Marked expression of Class I MHC gene products was evident on beta cells. In contrast, Class II MHC gene products were not identified on normal-appearing beta cells. Dendritic cells dispersed throughout the acinar and interstitial pancreas were markedly increased in number. The mononuclear cell infiltrate contained few cells (1-15%) recognized by a pan-T cell marker. Although it is possible that this passive transfer model might differ considerably from the spontaneously occurring diabetic state in the rat, this study suggests that 1) Class I, rather than Class II, MHC gene expression may be pivotal to beta-cell injury in diabetic rats, and 2) non-T cells may constitute an effector cell population central to beta-cell necrosis in Type I diabetes mellitus. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:3276208

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

    PubMed

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

    2008-12-01

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

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

    PubMed

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

    2008-01-01

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

  15. Heterogeneity of the Pancreatic Beta Cell

    PubMed Central

    Gutierrez, Giselle Dominguez; Gromada, Jesper; Sussel, Lori

    2017-01-01

    The pancreatic beta cell functions as a key regulator of blood glucose levels by integrating a variety of signals in response to changing metabolic demands. Variations in beta cell identity that translate into functionally different subpopulations represent an interesting mechanism to allow beta cells to efficiently respond to diverse physiological and pathophysiological conditions. Recently, there is emerging evidence that morphological and functional differences between beta cells exist. Furthermore, the ability of novel single cell technologies to characterize the molecular identity of individual beta cells has created a new era in the beta cell field. These studies are providing important novel information about the origin of beta cell heterogeneity, the type and proportions of the different beta cell subpopulations, as well as their intrinsic properties. Furthermore, characterization of different beta cell subpopulations that could variably offer protection from or drive progression of diabetes has important clinical implications in diabetes prevention, beta cell regeneration and stem cell treatments. In this review, we will assess the evidence that supports the existence of heterogeneous populations of beta cells and the factors that could influence their formation. We will also address novel studies using islet single cell analysis that have provided important information toward understanding beta cell heterogeneity and discuss the caveats that may be associated with these new technologies. PMID:28321233

  16. Differential sensitivity to beta-cell secretagogues in cultured rat pancreatic islets exposed to human interleukin-1 beta.

    PubMed

    Eizirik, D L; Sandler, S; Hallberg, A; Bendtzen, K; Sener, A; Malaisse, W J

    1989-08-01

    The early stages of insulin-dependent diabetes mellitus are characterized by a selective inability to secrete insulin in response to glucose, coupled to a better response to nonnutrient secretagogues. The deficient glucose response may be a result of the autoimmune process directed toward the beta-cells. Interleukin-1 (IL-1) has been suggested to be one possible mediator of immunological damage of the beta-cells. In the present study we characterized the sensitivity of beta-cells to different secretagogues after human recombinant IL-1 beta (rIL-1 beta) exposure. Furthermore, experiments were performed to clarify the biochemical mechanisms behind the defective insulin response observed in these islets. Rat pancreatic islets were isolated and kept in tissue culture (medium RPMI-1640 plus 10% calf serum) for 5 days. The islets were subsequently exposed to 60 pM human recombinant IL-1 beta during 48 h in the same culture conditions as above and examined immediately after IL-1 exposure. The rIL-1 beta-treated islets showed a marked reduction of glucose-stimulated insulin release. Stimulation with arginine plus different glucose concentrations, and leucine plus glutamine partially counteracted the rIL-1 beta-induced reduction of insulin release. The activities of the glycolytic enzymes hexokinase, glucokinase, and glyceraldehyde 3-phosphate dehydrogenase, were similar in control and IL-1-exposed islets. Treatment with IL-1 also did not impair the activities of NADH+- and NADPH+-dependent glutamate dehydrogenase, glutamate-aspartate transaminase, glutamate-alanine transaminase, citrate synthase, and NAD+-linked isocitrate dehydrogenase. The oxidation of D-[6-14C]glucose and L-[U-14C]leucine were decreased by 50% in IL-1-treated islets. Furthermore, there was a significant decrease in the ratios of [2-14C]pyruvate oxidation/[1-14C]pyruvate decarboxylation and L-[U-14C]leucine oxidation/L-[1-14C]leucine decarboxylation, indicating that IL-1 decreases the proportion of

  17. Control of beta-cell differentiation by the pancreatic mesenchyme.

    PubMed

    Attali, Myriam; Stetsyuk, Volodymyr; Basmaciogullari, Annie; Aiello, Virginie; Zanta-Boussif, Maria A; Duvillie, Bertrand; Scharfmann, Raphael

    2007-05-01

    The importance of mesenchymal-epithelial interactions for normal development of the pancreas was recognized in the early 1960s, and mesenchymal signals have been shown to control the proliferation of early pancreatic progenitor cells. The mechanisms by which the mesenchyme coordinates cell proliferation and differentiation to produce the normal number of differentiated pancreatic cells are not fully understood. Here, we demonstrate that the mesenchyme positively controls the final number of beta-cells that develop from early pancreatic progenitor cells. In vitro, the number of beta-cells that developed from rat embryonic pancreatic epithelia was larger in cultures with mesenchyme than without mesenchyme. The effect of mesenchyme was not due to an increase in beta-cell proliferation but was due to increased proliferation of early pancreatic duodenal homeobox-1 (PDX1)-positive progenitor cells, as confirmed by bromodeoxyuridine incorporation. Consequently, the window during which early PDX1(+) pancreatic progenitor cells differentiated into endocrine progenitor cells expressing Ngn3 was extended. Fibroblast growth factor 10 mimicked mesenchyme effects on proliferation of early PDX1(+) progenitor cells and induction of Ngn3 expression. Taken together, our results indicate that expansion of early PDX1(+) pancreatic progenitor cells represents a way to increase the final number of beta-cells developing from early embryonic pancreas.

  18. Effect of coriander seed (Coriandrum sativum L.) ethanol extract on insulin release from pancreatic beta cells in streptozotocin-induced diabetic rats.

    PubMed

    Eidi, Maryam; Eidi, Akram; Saeidi, Ali; Molanaei, Saadat; Sadeghipour, Alireza; Bahar, Massih; Bahar, Kamal

    2009-03-01

    Coriander (Coriandrum sativum L.) is grown as a spice crop all over the world. The seeds have been used to treat indigestion, diabetes, rheumatism and pain in the joints. In the present study, an ethanol extract of the seeds was investigated for effects on insulin release from the pancreatic beta cells in streptozotocin-induced diabetic rats. Blood samples were drawn from the retro-orbital sinus before and 1.5, 3 and 5 h after administration of the seed extract. Serum glucose levels were determined by the glucose oxidase method. To determine the insulin releasing activity, after extract treatment the animals were anaesthetized by diethyl ether, the pancreas was excised, fixed in 10% formaldehyde and embedded in paraffin for sectioning. Pancreatic sections of 5 microm were processed for examination of insulin-releasing activity using an immunocytochemistry kit. The results showed that administration of the ethanol extract (200 and 250 mg/kg, i.p.) exhibited a significant reduction in serum glucose. Administration of streptozotocin decreased the number of beta cells with insulin secretory activity in comparison with intact rats, but treatment with the coriander seed extract (200 mg/kg) increased significantly the activity of the beta cells in comparison with the diabetic control rats. The extract decreased serum glucose in streptozotocin-induced diabetic rats and increased insulin release from the beta cells of the pancreas.

  19. Characterization of P4 ATPase Phospholipid Translocases (Flippases) in Human and Rat Pancreatic Beta Cells: THEIR GENE SILENCING INHIBITS INSULIN SECRETION.

    PubMed

    Ansari, Israr-ul H; Longacre, Melissa J; Paulusma, Coen C; Stoker, Scott W; Kendrick, Mindy A; MacDonald, Michael J

    2015-09-18

    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 exocytosis of the vesicle contents of secretory cells. Our recent study of insulin secretory granules (ISG) (MacDonald, M. J., Ade, L., Ntambi, J. M., Ansari, I. H., and Stoker, S. W. (2015) Characterization of phospholipids in insulin secretory granules in pancreatic beta cells and their changes with glucose stimulation. J. Biol. Chem. 290, 11075-11092) suggested that phosphatidylserine and other phospholipids, such as phosphatidylethanolamine, in ISG could play important roles in docking and fusion of ISG to the plasma membrane in the pancreatic beta cell during insulin exocytosis. P4 ATPase flippases translocate primarily phosphatidylserine and, to a lesser extent, phosphatidylethanolamine across the lipid bilayers of intracellular vesicles and plasma membranes to the cytosolic leaflets of these membranes. CDC50A is a protein that forms a heterodimer with P4 ATPases to enhance their translocase catalytic activity. We found that the predominant P4 ATPases in pure pancreatic beta cells and human and rat pancreatic islets were ATP8B1, ATP8B2, and ATP9A. ATP8B1 and CDC50A were highly concentrated in ISG. ATP9A was concentrated in plasma membrane. Gene silencing of individual P4 ATPases and CDC50A inhibited glucose-stimulated insulin release in pure beta cells and in human pancreatic islets. This is the first characterization of P4 ATPases in beta cells. The results support roles for P4 ATPases in translocating phosphatidylserine to the cytosolic leaflets of ISG and the plasma membrane to facilitate the docking and fusion of ISG to the plasma membrane during insulin exocytosis.

  20. ATP-sensitive K+ channels in rat pancreatic beta-cells: modulation by ATP and Mg2+ ions.

    PubMed Central

    Ashcroft, F M; Kakei, M

    1989-01-01

    1. The inside-out configuration of the patch-clamp method was used to study the effects of MgATP, free ATP and Mg2+ on single ATP-sensitive K+ channel currents in rat pancreatic beta-cells. 2. Magnesium ions caused a marked reduction of channel activity: 5 mM-free Mg2+ produced a 50% reduction in the activity of inward currents recorded at -60 mV in symmetrical K+ concentrations. 3. Inhibition of channel activity by MgATP does not involve phosphorylation as both free ATP (i.e. ATP in the absence of divalent cations) and non-hydrolysable ATP analogues were effective inhibitors. 4. Magnesium ions produced a striking reduction in the ability of ATP (total) to inhibit channel activity. When channel activity was plotted as a function of the total ATP concentration, the Ki for channel inhibition was 4 microM in Mg2(+)-free solution, compared to a Ki of 26 microM in the presence of 2 mM-Mg2+. The shape of the relationship between channel activity and the total ATP concentration was not changed by Mg2+. When channel activity was plotted as a function of the free ATP concentration, however, Mg2+ had little effect on Ki. This suggests that free ATP is the more potent inhibitor of channel activity and that MgATP has little inhibitory effect. 5. ATP analogues that dissociate only as far as the tribasic form were also able to inhibit channel activity. This suggests that both ATP4- and ATPH3- can block the channel. 6. Like ATP, ADP was more effective at inhibiting channel activity in the absence of Mg2+, that is as the free base. The non-hydrolysable ATP analogues AMP-PNP and AMP-PCP, however, were more effective in the presence of Mg2+. 7. It is suggested that (1) the potency of inhibition is related to the amount of negative charge carried by the ion and (2) the intracellular concentration of free ATP will be an important modulator of channel activity in the intact beta-cell. PMID:2691645

  1. Environmental Contaminants and Pancreatic Beta-Cells

    PubMed Central

    Fabricio, Gabriel; Malta, Ananda; Chango, Abalo; De Freitas Mathias, Paulo Cezar

    2016-01-01

    Despite health policies as well as clinical and research efforts, diabetes prevalence is still rising around the world. A multitude of causes have been suggested for this increase, mostly related to familial background, the occidental diet which is rich in fat/carbohydrates, and sedentary life style. Type 2 diabetes involves malfunctions of the primary pancreatic beta-cells, usually attributed to local damage; however, it can be associated with other stressful environmental agents, such as chemical contaminants from food, plastic and air, among others. Indeed, exposure to these chemical agents during perinatal and adolescent life can increase the risk of developing cardiometabolic diseases later in life. This review explores data showing which environmental chemical agents may produce injury in beta-cells and further impair the insulinotropic process of type 2 diabetes. Additionally, it points the need to also consider unusual causes of metabolic diseases, such as environmental contaminants. PMID:27087124

  2. Chlamydia pneumoniae promotes dysfunction of pancreatic beta cells.

    PubMed

    Rodriguez, Annette R; Plascencia-Villa, Germán; Witt, Colleen M; Yu, Jieh-Juen; José-Yacamán, Miguel; Chambers, James P; Perry, George; Guentzel, M Neal; Arulanandam, Bernard P

    2015-06-01

    The human pathogen Chlamydia pneumoniae has been implicated in chronic inflammatory diseases including type 2 diabetes. Therefore, we designed a study to evaluate pancreatic beta cells and mast cells during chlamydial infection. Our study revealed that C. pneumoniae infected mast cells significantly (p<0.005) decreased beta cell ATP and insulin production, in contrast to uninfected mast cells co-cultured with beta cells. Infected mast cells exhibited pyknotic nuclei and active caspase-3 and caspase-1 expression. Additionally, ex vivo analyses of tissues collected from C. pneumoniae infected mice showed increased interleukin-1β production in splenocytes and pancreatic tissues as was observed with in vitro mast cell-beta cell co-cultures during C. pneumoniae infection. Notably, infected mast cells promoted beta cell destruction. Our findings reveal the negative effect of C. pneumoniae on mast cells, and the consequential impact on pancreatic beta cell function and viability.

  3. Adaptations of alpha2- and beta-cells of rat and mouse pancreatic islets to starvation, to refeeding after starvation, and to obesity.

    PubMed Central

    Matschinsky, F M; Rujanavech, C; Pagliara, A; Norfleet, W T

    1980-01-01

    The effects of starvation and refeeding and of obesity on pancreatic alpha2- and beta-cell responses to glucose or tolbutamide were studied with the isolated rat or mouse pancreas perfused with an amino acid mixture in the presence and absence of glucose. It was observed that the physiological adaptation to a regimen of fasting and realimentation and to obesity differed greatly in the two types of endocrine cells. Whereas beta-cells of rats showed a dramatic reduction of glucose- and tolbutamide-stimulated insulin release during starvation that was reversed by refeeding, alpha2-cells preserved their response to stimulators and inhibitors during this experimental manipulation. Amino acid stimulation of glucagon release occurred equally well with the pancreas from fed and starved rats and was suppressed efficiently by glucose and tolbutamide in both nutritional states. Surprisingly, the rate of onset of glucose suppression of alpha2-cells was significantly higher in the fasted than in the fed state. This glucose hypersensitivity was apparent 2 d after after food deprivation and had disappeared again on the 2nd d of refeeding. In the pancreas from animals starved for 3 d, glucose and tolbutamide suppression of alpha2-cells took place in the absence of demonstrable changes of insulin release. In the isolated perfused pancreas taken from the hyperphagic obese hyperglycemic mouse (C57 Black/6J; ob/ob), the observed rate of insulin secretion as a result of a combined stimulus of amino acids and glucose and of glucagon release stimulated by amino acids was about four times higher than achieved by the pancreas of lean controls. However, glucose was unable to suppress the alpha2-cells in the pancreas of obese animals, in spite of the hypersection of the beta-cells, again in contrast to the alpha2-cells of controls that were readily inhibited by glucose. These data imply that the acute suppression of alpha2-cells by glucose is largely independent of a concomitant surge of

  4. Impaired Pancreatic Beta Cell Function by Chronic Intermittent Hypoxia

    PubMed Central

    Wang, Ning; Khan, Shakil A.; Prabhakar, Nanduri R.; Nanduri, Jayasri

    2013-01-01

    Breathing disorders with recurrent apnea produce periodic decreases in arterial blood O2 or chronic intermittent hypoxia (CIH). Recurrent apnea patients and CIH-exposed rodents exhibit several co-morbidities including diabetes. However, the effects of CIH on pancreatic beta cell function are not known. In the present study, we investigated pancreatic beta cell function in C57BL6 mice exposed to 30 days of CIH. CIH-exposed mice exhibited elevated levels of fasting plasma insulin, but comparable glucose levels, and higher homeostasis model assessment (HOMA), indicating insulin resistance. Pancreatic beta cell morphology was unaltered in CIH- exposed mice. Insulin content was decreased in CIH-exposed beta cells, and this effect was associated with increased proinsulin levels. mRNA and protein levels of the enzyme pro-hormone convertase 1 (PC1) which converts proinsulin to insulin were down regulated in CIH-treated islets. More importantly, glucose-stimulated insulin secretion (GSIS) was impaired in CIH-exposed mice and in isolated islets. Mitochondrial reactive oxygen species (ROS) levels were elevated in CIH-exposed pancreatic islets. Treatment of mice with mito-tempol, a scavenger of mitochondrial ROS during CIH exposure, prevented the augmented insulin secretion and restored the proinsulin as well as HOMA values to control levels. These results demonstrate that CIH leads to pancreatic beta cell dysfunction manifested by augmented basal insulin secretion, insulin resistance, defective proinsulin processing, impaired GSIS and mitochondrial ROS mediates the effects of CIH on pancreatic beta cell function. PMID:23709585

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

    SciTech Connect

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

    2013-12-06

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

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

    SciTech Connect

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

    2008-09-15

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

  7. Novel aspects on pancreatic beta-cell signal-transduction.

    PubMed

    Leibiger, Ingo B; Brismar, Kerstin; Berggren, Per-Olof

    2010-05-21

    Pancreatic beta-cells release insulin in appropriate amounts in order to keep blood glucose levels within physiological limits. Failure to do so leads to the most common metabolic disorder in man, diabetes mellitus. The glucose-stimulus/insulin-secretion coupling represents a sophisticated interplay between glucose and a variety of modulatory factors. These factors are provided by the blood supply (such as nutrients, vitamins, incretins etc.), the nerval innervations, cell-cell contacts as well as by paracrine and autocrine feedback loops within the pancreatic islet of Langerhans. However, the underlying mechanisms of their action remain poorly understood. In the present mini-review we discuss novel aspects of selective insulin signaling in the beta-cell and novel insights into the role of higher inositol phosphates in insulin secretion. Finally we present a newly developed experimental platform that allows non-invasive and longitudinal in vivo imaging of pancreatic islet/beta-cell biology at single-cell resolution.

  8. Uncovering Factors Related to Pancreatic Beta-Cell Function

    PubMed Central

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

    2016-01-01

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

  9. PROTEOMICS ANALYSIS OF ROUGH ENDOPLASMIC RETICULUM IN PANCREATIC BETA CELLS

    PubMed Central

    Lee, Jin-sook; Wu, Yanning; Skallos, Patracia; Fang, Jingye; Zhang, Xuebao; Karnovsky, Alla; Woods, James; Stemmer, Paul M.; Liu, Ming; Zhang, Kezhong; Chen, Xuequn

    2015-01-01

    Pancreatic beta cells have well-developed endoplasmic reticulum (ER) to accommodate for the massive production and secretion of insulin. ER homeostasis is vital for normal beta cell function. Perturbation of ER homeostasis contributes to beta cell dysfunction in both type 1 and type 2 diabetes. To systematically identify the molecular machinery responsible for proinsulin biogenesis and maintenance of beta cell ER homeostasis, a widely used mouse pancreatic beta cell line, MIN6 cell was used to purify rough ER. Two different purification schemes were utilized. In each experiment, the ER pellets were solubilized and analyzed by one dimensional SDS-PAGE coupled with HPLC-MS/MS. A total of 1467 proteins were identified in three experiments with ≥95% confidence, among which 1117 proteins were found in at least two separate experiments and 737 proteins found in all three experiments. Gene ontology analysis revealed a comprehensive profile of known and novel players responsible for proinsulin biogenesis and ER homeostasis. Further bioinformatics analysis also identified potential beta cell specific ER proteins as well as ER proteins present in the risk genetic loci of type 2 diabetes. This dataset defines a molecular environment in the ER for proinsulin synthesis, folding and export and laid a solid foundation for further characterizations of altered ER homeostasis under diabetes-causing conditions. PMID:25546123

  10. Re-exposure to beta cell autoantigens in pancreatic allograft recipients with preexisting beta cell autoantibodies.

    PubMed

    Mujtaba, Muhammad Ahmad; Fridell, Jonathan; Book, Benita; Faiz, Sara; Sharfuddin, Asif; Wiebke, Eric; Rigby, Mark; Taber, Tim

    2015-11-01

    Re-exposure to beta cell autoantigens and its relevance in the presence of donor-specific antibodies (DSA) in pancreatic allograft recipients is not well known. Thirty-three patients requiring a pancreas transplant were enrolled in an IRB approved study. They underwent prospective monitoring for DSA and beta cell autoantibody (BCAA) levels to GAD65, insulinoma-associated antigen 2 (IA-2), insulin (micro-IAA [mIAA]), and islet-specific zinc transporter isoform-8 (ZnT8). Twenty-five (75.7%) had pre-transplant BCAA. Twenty had a single antibody (mIAA n = 15, GAD65 n = 5); five had two or more BCAA (GAD65 + mIAA n = 2, GAD65 + mIAA+IA-2 n = 2, GA65 + mIAA+IA-2 + ZnT8 = 1). No changes in GAD65 (p > 0.29), IA-2 (>0.16), and ZnT8 (p > 0.07) were observed between pre-transplant and post-transplant at 6 or 12 months. A decrease in mIAA from pre- to post-6 months (p < 0.0001), 12 months (p < 0.0001), and from post-6 to post-12 months (p = 0.0002) was seen. No new BCAA was observed at one yr. Seven (21.0%) developed de novo DSA. The incidence of DSA was 24% in patients with BCAA vs. 25% in patients without BCAA (p = 0.69). Pancreatic allograft function of patients with vs. without BCAA, and with and without BCAA + DSA was comparable until last follow-up (three yr). Re-exposure to beta cell autoantigens by pancreas transplant may not lead to increased levels or development of new BCAA or pancreatic allograft dysfunction.

  11. Effect of fluoroquinolones on mitochondrial function in pancreatic beta cells.

    PubMed

    Ghaly, Hany; Jörns, Anne; Rustenbeck, Ingo

    2014-02-14

    Hyper- and hypoglycaemias are known side effects of fluoroquinolone antibiotics, resulting in a number of fatalities. Fluoroquinolone-induced hypoglycaemias are due to stimulated insulin release by the inhibition of the KATP channel activity of the beta cell. Recently, it was found that fluoroquinolones were much less effective on metabolically intact beta cells than on open cell preparations. Thus the intracellular effects of gatifloxacin, moxifloxacin and ciprofloxacin were investigated by measuring NAD(P)H- and FAD-autofluorescence, the mitochondrial membrane potential, and the adenine nucleotide content of isolated pancreatic islets and beta cells. 100 μM of moxifloxacin abolished the NAD(P)H increase elicited by 20mM glucose, while gatifloxacin diminished it and ciprofloxacin had no significant effect. This pattern was also seen with islets from SUR1 Ko mice, which have no functional KATP channels. Moxifloxacin also diminished the glucose-induced decrease of FAD-fluorescence, which reflects the intramitochondrial production of reducing equivalents. Moxifloxacin, but not ciprofloxacin or gatifloxacin significantly reduced the effect of 20mM glucose on the ATP/ADP ratio. The mitochondrial hyperpolarization caused by 20mM glucose was partially antagonized by moxifloxacin, but not by ciprofloxacin or gatifloxacin. Ultrastructural analyses after 20 h tissue culture showed that all three compounds (at 10 and 100 μM) diminished the number of insulin secretory granules and that gatifloxacin and ciprofloxacin, but not moxifloxacin induced fission/fusion configurations of the beta cell mitochondria. In conclusion, fluoroquinolones affect the function of the mitochondria in pancreatic beta cells which may diminish the insulinotropic effect of KATP channel closure and contribute to the hyperglycaemic episodes.

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

    SciTech Connect

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

    2012-11-15

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

  13. Crystalline structures in human pancreatic beta cell adenoma.

    PubMed

    Mori, H; Kawai, T; Tanaka, T; Fujii, M; Takahashi, M; Miyashita, T

    1978-05-01

    An electron microscopic observation on a pancreatic tumor removed from a 34-year-old woman revealed the fine structural morphology of a functional beta cell adenoma. Characteristic PAS positive crystalline structures were frequently observed in the cytoplasm of the tumor cells. They were not bounded by a membrane and had a rectangular or irregular hexagonal shape. Highly regular patterns were seen as such as lattice or honeycomb and parallel ripple structures. They are similar to the Reinke's crystal or crystalline structures reported in human hepatocytes suffering from several different diseases and considered as a protein-carbohydrate complex. Occasionally, small paracrystalline structures appeared to indicate an immature type of these structures in the opaque fine fibrillar mass. Crystalline or paracrystalline structures were not detected in the normal pancreatic tissue removed with the tumor from the patient.

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

    SciTech Connect

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

    2011-12-15

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

  15. Molecular regulation of monocyte chemoattractant protein-1 expression in pancreatic beta-cells.

    PubMed

    Kutlu, Burak; Darville, Martine I; Cardozo, Alessandra K; Eizirik, Décio L

    2003-02-01

    Pancreatic beta-cells are selectively destroyed during the course of type 1 diabetes. In the early stages of the disease, inflammatory infiltrates of mononuclear cells, containing predominantly monocytes and T-cells, are present in the islets (insulitis). Chemokines, such as monocyte chemoattractant protein-1 (MCP-1), play a key role in the recruitment and activation of these immunocytes. We have previously described cytokine-induced MCP-1 gene expression in human and rat pancreatic islets. In the present study, the transcriptional regulation by cytokines of the rat MCP-1 gene in fluorescence-activated cell sorting-purified rat beta-cells, insulin-producing INS-1E cells, and RINm5F cells was investigated. Transient transfections with luciferase-reporter constructs identified an interleukin (IL)-1beta-responsive enhancer region between -2,180 bp and -2,478 bp. Mutation of either of the two nuclear factor (NF)-kappaB sites present in this region abrogated IL-1beta-induced MCP-1 promoter activity. Binding of NF-kappaB to the two sites was shown in vitro by gel shift assays, while supershift assays revealed the presence of p65/p50 heterodimers and p65 homodimers. In vivo binding of NF-kappaB was confirmed by chromatin immunoprecipitation assay. Blocking of NF-kappaB activation in cytokine-exposed primary beta-cells by an adenovirus overexpressing a nondegradable form of IkappaBalpha or by pyrrolidine dithiocarbamate decreased IL-1beta-induced MCP-1 mRNA expression. We conclude that NF-kappaB plays an important role for MCP-1 expression in beta-cells. This transcription factor may be an interesting target for ex vivo gene therapy before islet transplantation.

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

    SciTech Connect

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

    2006-07-01

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

  17. Selective beta-cell differentiation of dissociated embryonic pancreatic precursor cells cultured in synthetic polyethylene glycol hydrogels.

    PubMed

    Mason, Mariah N; Mahoney, Melissa J

    2009-06-01

    Continuing advances in islet cell transplantation have been promising; however, several limitations, including severe shortage of transplantable islets, hinder the widespread use of this therapy. Pancreatic precursor cells are one alternative to cadaveric donor islets. These cells found in the developing pancreatic buds are capable of self-renewal and also have the innate ability to become insulin-producing beta-cells. For this work, bioinert polyethylene glycol (PEG) hydrogels were chosen as the supportive three-dimensional matrix for encapsulation of dissociated pancreatic precursor cells obtained from the dorsal pancreatic bud of day-15 rat embryos. This culture system was selected in order to eliminate cell-extracellular matrix and cell-cell signal heterogeneity present when intact pancreatic buds are embedded in protein-based gels, the typical in vitro culture conditions used to study this cell population. In this study it was found that (1) dissociated precursor cells maintain a robust viability for 7 days in PEG hydrogel culture, (2) encapsulated cells selectively differentiate into insulin-expressing beta-cells, and (3) differentiated beta-cells have releasable insulin stores, but are not achieving a mature, glucose responsive phenotype. These findings suggest that encapsulating dissociated pancreatic precursor cells in an environment designed to minimize the heterogeneous signaling cues present during development or in standard culture conditions generates a population highly enriched in pancreatic beta-cells; however, future efforts must focus on achieving glucose responsiveness in this cell population. Further, these results indicate that differentiation down a beta-cell lineage may be the default pathway in pancreatic development.

  18. New insights into fatty acid modulation of pancreatic beta-cell function.

    PubMed

    Haber, Esther P; Procópio, Joaquim; Carvalho, Carla R O; Carpinelli, Angelo R; Newsholme, Philip; Curi, Rui

    2006-01-01

    Insulin resistance states as found in type 2 diabetes and obesity are frequently associated with hyperlipidemia. Both stimulatory and detrimental effects of free fatty acids (FFA) on pancreatic beta cells have long been recognized. Acute exposure of the pancreatic beta cell to both high glucose concentrations and saturated FFA results in a substantial increase of insulin release, whereas a chronic exposure results in desensitization and suppression of secretion. Reduction of plasma FFA levels in fasted rats or humans severely impairs glucose-induced insulin release but palmitate can augment insulin release in the presence of nonstimulatory concentrations of glucose. These results imply that changes in physiological plasma levels of FFA are important for regulation of beta-cell function. Although it is widely accepted that fatty acid (FA) metabolism (notably FA synthesis and/or formation of LC-acyl-CoA) is necessary for stimulation of insulin secretion, the key regulatory molecular mechanisms controlling the interplay between glucose and fatty acid metabolism and thus insulin secretion are not well understood but are now described in detail in this review. Indeed the correct control of switching between FA synthesis or oxidation may have critical implications for beta-cell function and integrity both in vivo and in vitro. LC-acyl-CoA (formed from either endogenously synthesized or exogenous FA) controls several aspects of beta-cell function including activation of certain types of PKC, modulation of ion channels, protein acylation, ceramide- and/or NO-mediated apoptosis, and binding to and activating nuclear transcriptional factors. The present review also describes the possible effects of FAs on insulin signaling. We have previously reported that acute exposure of islets to palmitate up-regulates some key components of the intracellular insulin signaling pathway in pancreatic islets. Another aspect considered in this review is the potential source of fatty acids

  19. Cell therapies for pancreatic beta-cell replenishment.

    PubMed

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

    2016-07-11

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

  20. TRPM3 channels provide a regulated influx pathway for zinc in pancreatic beta cells.

    PubMed

    Wagner, Thomas F J; Drews, Anna; Loch, Sabine; Mohr, Florian; Philipp, Stephan E; Lambert, Sachar; Oberwinkler, Johannes

    2010-09-01

    Zinc is stored in insulin-containing dense core vesicles of pancreatic beta-cells where it forms crystals together with insulin and calcium ions. Zinc ions are therefore released together with insulin upon exocytosis of these vesicles. Consequently, pancreatic beta-cells need to take up large amounts of zinc from the extracellular space across their plasma membrane. The pathways for zinc uptake are only partially understood. TRPM3 channels are present in pancreatic beta-cells and can be activated by the endogenous steroid pregnenolone sulfate. We demonstrate here that recombinant TRPM3 channels are highly permeable for many divalent cations, in particular also for zinc ions. Importantly, TRPM3 channels endogenously expressed in pancreatic beta-cells are also highly permeable for zinc ions. Using FluoZin3 to image changes of the intracellular zinc concentration, we show that pancreatic beta-cells take up zinc through TRPM3 channels even when extracellular zinc concentrations are low and physiological levels of calcium and magnesium are present. Activation of TRPM3 channels also leads to depolarization of beta-cells and to additional zinc influx through voltage-gated calcium channels. Our data establish that TRPM3 channels constitute a regulated entry pathway for zinc ions in pancreatic beta-cells.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2008-01-01

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

  3. Cocoa phenolic extract protects pancreatic beta cells against oxidative stress.

    PubMed

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

    2013-07-31

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

  4. Metabolic Stress and Compromised Identity of Pancreatic Beta Cells

    PubMed Central

    Swisa, Avital; Glaser, Benjamin; Dor, Yuval

    2017-01-01

    Beta cell failure is a central feature of type 2 diabetes (T2D), but the molecular underpinnings of the process remain only partly understood. It has been suggested that beta cell failure in T2D involves massive cell death. Other studies ascribe beta cell failure to cell exhaustion, due to chronic oxidative or endoplasmic reticulum stress leading to cellular dysfunction. More recently it was proposed that beta cells in T2D may lose their differentiated identity, possibly even gaining features of other islet cell types. The loss of beta cell identity appears to be driven by glucotoxicity inhibiting the activity of key beta cell transcription factors including Pdx1, Nkx6.1, MafA and Pax6, thereby silencing beta cell genes and derepressing alternative islet cell genes. The loss of beta cell identity is at least partly reversible upon normalization of glycemia, with implications for the reversibility of T2D, although it is not known if beta cell failure reaches eventually a point of no return. In this review we discuss current evidence for metabolism-driven compromised beta cell identity, key knowledge gaps and opportunities for utility in the treatment of T2D. PMID:28270834

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

    SciTech Connect

    Goalstone, Marc; Kamath, Vasudeva; Kowluru, Anjaneyulu

    2010-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  7. Voltage-dependent metabolic regulation of Kv2.1 channels in pancreatic beta-cells.

    PubMed

    Yoshida, Masashi; Nakata, Masanori; Yamato, Shiho; Dezaki, Katsuya; Sugawara, Hitoshi; Ishikawa, San-e; Kawakami, Masanobu; Yada, Toshihiko; Kakei, Masafumi

    2010-05-28

    Voltage-gated potassium channels (Kv channels) play a crucial role in formation of action potentials in response to glucose stimulation in pancreatic beta-ells. We previously reported that the Kv channel is regulated by glucose metabolism, particularly by MgATP. We examined whether the regulation of Kv channels is voltage-dependent and mechanistically related with phosphorylation of the channels. In rat pancreatic beta-cells, suppression of glucose metabolism with low glucose concentrations of 2.8mM or less or by metabolic inhibitors decreased the Kv2.1-channel activity at positive membrane potentials, while increased it at potentials negative to -10 mV, suggesting that modulation of Kv channels by glucose metabolism is voltage-dependent. Similarly, in HEK293 cells expressing the recombinant Kv2.1 channels, 0mM but not 10mM MgATP modulated the channel activity in a manner similar to that in beta-cells. Both steady-state activation and inactivation kinetics of the channel were shifted toward the negative potential in association with the voltage-dependent modulation of the channels by cytosolic dialysis of alkaline phosphatase in beta-cells. The modulation of Kv-channel current-voltage relations were also observed during and after glucose-stimulated electrical excitation. These results suggest that the cellular metabolism including MgATP production and/or channel phosphorylation/dephosphorylation underlie the physiological modulation of Kv2.1 channels during glucose-induced insulin secretion.

  8. Novel members of quinoline compound family enhance insulin secretion in RIN-5AH beta cells and in rat pancreatic islet microtissue

    PubMed Central

    Orfi, Z.; Waczek, F.; Baska, F.; Szabadkai, I.; Torka, R.; Hartmann, J.; Orfi, L.; Ullrich, A.

    2017-01-01

    According to clinical data, some tyrosine kinase inhibitors (TKIs) possess antidiabetic effects. Several proposed mechanisms were assigned to them, however their mode of action is not clear. Our hypothesis was that they directly stimulate insulin release in beta cells. In our screening approach we demonstrated that some commercially available TKIs and many novel synthesized analogues were able to induce insulin secretion in RIN-5AH beta cells. Our aim was to find efficient, more selective and less toxic compounds. Out of several hits, we chose members from a compound family with quinoline core structure for further investigation. Here we present the studies done with these novel compounds and reveal structure activity relationships and mechanism of action. One of the most potent compounds (compound 9) lost its affinity to kinases, but efficiently increased calcium influx. In the presence of calcium channel inhibitors, the insulinotropic effect was attenuated or completely abrogated. While the quinoline TKI, bosutinib substantially inhibited tyrosine phosphorylation, compound 9 had no such effect. Molecular docking studies further supported our data. We confirmed that some TKIs possess antidiabetic effects, moreover, we present a novel compound family developed from the TKI, bosutinib and optimized for the modulation of insulin secretion. PMID:28272433

  9. Novel members of quinoline compound family enhance insulin secretion in RIN-5AH beta cells and in rat pancreatic islet microtissue.

    PubMed

    Orfi, Z; Waczek, F; Baska, F; Szabadkai, I; Torka, R; Hartmann, J; Orfi, L; Ullrich, A

    2017-03-08

    According to clinical data, some tyrosine kinase inhibitors (TKIs) possess antidiabetic effects. Several proposed mechanisms were assigned to them, however their mode of action is not clear. Our hypothesis was that they directly stimulate insulin release in beta cells. In our screening approach we demonstrated that some commercially available TKIs and many novel synthesized analogues were able to induce insulin secretion in RIN-5AH beta cells. Our aim was to find efficient, more selective and less toxic compounds. Out of several hits, we chose members from a compound family with quinoline core structure for further investigation. Here we present the studies done with these novel compounds and reveal structure activity relationships and mechanism of action. One of the most potent compounds (compound 9) lost its affinity to kinases, but efficiently increased calcium influx. In the presence of calcium channel inhibitors, the insulinotropic effect was attenuated or completely abrogated. While the quinoline TKI, bosutinib substantially inhibited tyrosine phosphorylation, compound 9 had no such effect. Molecular docking studies further supported our data. We confirmed that some TKIs possess antidiabetic effects, moreover, we present a novel compound family developed from the TKI, bosutinib and optimized for the modulation of insulin secretion.

  10. Conditional and specific NF-kappaB blockade protects pancreatic beta cells from diabetogenic agents.

    PubMed

    Eldor, R; Yeffet, A; Baum, K; Doviner, V; Amar, D; Ben-Neriah, Y; Christofori, G; Peled, A; Carel, J C; Boitard, C; Klein, T; Serup, P; Eizirik, D L; Melloul, D

    2006-03-28

    Type 1 diabetes is characterized by the infiltration of inflammatory cells into pancreatic islets of Langerhans, followed by the selective and progressive destruction of insulin-secreting beta cells. Islet-infiltrating leukocytes secrete cytokines such as IL-1beta and IFN-gamma, which contribute to beta cell death. In vitro evidence suggests that cytokine-induced activation of the transcription factor NF-kappaB is an important component of the signal triggering beta cell apoptosis. To study the in vivo role of NF-kappaB in beta cell death, we generated a transgenic mouse line expressing a degradation-resistant NF-kappaB protein inhibitor (DeltaNIkappaBalpha), acting specifically in beta cells, in an inducible and reversible manner, by using the tet-on regulation system. In vitro, islets expressing the DeltaNIkappaBalpha protein were resistant to the deleterious effects of IL-1beta and IFN-gamma, as assessed by reduced NO production and beta-cell apoptosis. This effect was even more striking in vivo, where nearly complete protection against multiple low-dose streptozocin-induced diabetes was observed, with reduced intraislet lymphocytic infiltration. Our results show in vivo that beta cell-specific activation of NF-kappaB is a key event in the progressive loss of beta cells in diabetes. Inhibition of this process could be a potential effective strategy for beta-cell protection.

  11. mTOR links incretin signaling to HIF induction in pancreatic beta cells.

    PubMed

    Van de Velde, Sam; Hogan, Meghan F; Montminy, Marc

    2011-10-11

    Under feeding conditions, the incretin hormone GLP-1 promotes pancreatic islet viability by triggering the cAMP pathway in beta cells. Increases in PKA activity stimulate the phosphorylation of CREB, which in turn enhances beta cell survival by upregulating IRS2 expression. Although sustained GLP-1 action appears important for its salutary effects on islet function, the transient nature of CREB activation has pointed to the involvement of additional nuclear factors in this process. Following the acute induction of CREB-regulated genes, cAMP triggers a second delayed phase of gene expression that proceeds via the HIF transcription factor. Increases in cAMP promote the accumulation of HIF1α in beta cells by activating the mTOR pathway. As exposure to rapamycin disrupts GLP-1 effects on beta cell viability, these results demonstrate how a pathway associated with tumor growth also mediates salutary effects of an incretin hormone on pancreatic islet function.

  12. Novel aspects on signal-transduction in the pancreatic beta-cell.

    PubMed

    Berggren, Per-Olof; Leibiger, Ingo B

    2006-03-01

    The glucose-stimulus/insulin-secretion-coupling by the pancreatic beta-cell, which guarantees the maintenance of glucose homeostasis in man, is regulated by a sophisticated interplay between glucose and a plethora of additional factors. Besides other nutrients, incretins, nerval innervation, systemic growth factors as well as autocrine and paracrine regulatory loops within the islet of Langerhans modulate the function of the insulin-producing beta-cell. Although the modulatory role of these factors is well appreciated, the underlying molecular mechanisms involved remain poorly understood. However, in most cases beta-cell membrane receptors coupled primarily to either G-proteins or tyrosine kinases, which subsequently activate respective second messenger cascades, are involved. In the present mini-review we will discuss the role of signaling through some of these receptor-operated effector systems in the light of pancreatic beta-cell signal-transduction.

  13. Regeneration therapy of pancreatic beta cells: towards a cure for diabetes?

    PubMed

    Yamaoka, Takashi

    2002-09-06

    Regeneration therapy is an approach which could potentially move us towards a cure for type 1 diabetes. It is classified into three categories: (1) In vitro regeneration therapy using transplanted cultured cells, including ES cells, pancreatic stem cells, and beta-cell lines, in conjunction with immunosuppressive therapy or immunoisolation. (2) In ex vivo regeneration therapy, patients' own cells, such as bone marrow stem cells, are transiently removed and induced to differentiate into beta cells in vitro. At present, however, insulin-producing cells cannot be generated from bone marrow stem cells. (3) In in vivo regeneration therapy, impaired tissues regenerate from patients' own cells in vivo. beta-Cell neogenesis from non-beta-cells and beta-cell proliferation in vivo have been considered, particularly as regeneration therapies for type 2 diabetes. Regeneration therapy of pancreatic beta cells can be combined with various other therapeutic strategies, including islet transplantation, cell-based therapy, gene therapy, and drug therapy to promote beta-cell proliferation and neogenesis, and it is hoped that these strategies will, in the future, provide a cure for diabetes.

  14. Autophagy regulates pancreatic beta cell death in response to Pdx1 deficiency and nutrient deprivation.

    PubMed

    Fujimoto, Kei; Hanson, Piia T; Tran, Hung; Ford, Eric L; Han, Zhiqiang; Johnson, James D; Schmidt, Robert E; Green, Karen G; Wice, Burton M; Polonsky, Kenneth S

    2009-10-02

    There are three types of cell death; apoptosis, necrosis, and autophagy. The possibility that activation of the macroautophagy (autophagy) pathway may increase beta cell death is addressed in this study. Increased autophagy was present in pancreatic islets from Pdx1(+/-) mice with reduced insulin secretion and beta cell mass. Pdx1 expression was reduced in mouse insulinoma 6 (MIN6) cells by delivering small hairpin RNAs using a lentiviral vector. The MIN6 cells died after 7 days of Pdx1 deficiency, and autophagy was evident prior to the onset of cell death. Inhibition of autophagy prolonged cell survival and delayed cell death. Nutrient deprivation increased autophagy in MIN6 cells and mouse and human islets after starvation. Autophagy inhibition partly prevented amino acid starvation-induced MIN6 cell death. The in vivo effects of reduced autophagy were studied by crossing Pdx1(+/-) mice to Becn1(+/-) mice. After 1 week on a high fat diet, 4-week-old Pdx1(+/-) Becn1(+/-) mice showed normal glucose tolerance, preserved beta cell function, and increased beta cell mass compared with Pdx1(+/-) mice. This protective effect of reduced autophagy had worn off after 7 weeks on a high fat diet. Increased autophagy contributes to pancreatic beta cell death in Pdx1 deficiency and following nutrient deprivation. The role of autophagy should be considered in studies of pancreatic beta cell death and diabetes and as a target for novel therapeutic intervention.

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

    PubMed Central

    Oh, Yoon Sin

    2015-01-01

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

  16. Regulation of pancreatic islet beta-cell mass by growth factor and hormone signaling.

    PubMed

    Huang, Yao; Chang, Yongchang

    2014-01-01

    Dysfunction and destruction of pancreatic islet beta cells is a hallmark of diabetes. Better understanding of cellular signals in beta cells will allow development of therapeutic strategies for diabetes, such as preservation and expansion of beta-cell mass and improvement of beta-cell function. During the past several decades, the number of studies analyzing the molecular mechanisms, including growth factor/hormone signaling pathways that impact islet beta-cell mass and function, has increased exponentially. Notably, somatolactogenic hormones including growth hormone (GH), prolactin (PRL), and insulin-like growth factor-1 (IGF-1) and their receptors (GHR, PRLR, and IGF-1R) are critically involved in beta-cell growth, survival, differentiation, and insulin secretion. In this chapter, we focus more narrowly on GH, PRL, and IGF-1 signaling, and GH-IGF-1 cross talk. We also discuss how these signaling aspects contribute to the regulation of beta-cell proliferation and apoptosis. In particular, our novel findings of GH-induced formation of GHR-JAK2-IGF-1R protein complex and synergistic effects of GH and IGF-1 on beta-cell signaling, proliferation, and antiapoptosis lead to a new concept that IGF-1R may serve as a proximal component of GH/GHR signaling.

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

    SciTech Connect

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

    2012-06-29

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

  18. On the coherent behavior of pancreatic beta cell clusters

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  19. Microbial phenolic metabolites improve glucose-stimulated insulin secretion and protect pancreatic beta cells against tert-butyl hydroperoxide-induced toxicity via ERKs and PKC pathways.

    PubMed

    Fernández-Millán, Elisa; Ramos, Sonia; Alvarez, Carmen; Bravo, Laura; Goya, Luis; Martín, María Ángeles

    2014-04-01

    Oxidative stress is accepted as one of the causes of beta cell failure in type 2 diabetes. Therefore, identification of natural antioxidant agents that preserve beta cell mass and function is considered an interesting strategy to prevent or treat diabetes. Recent evidences indicated that colonic metabolites derived from flavonoids could possess beneficial effects on various tissues. The aim of this work was to establish the potential anti-diabetic properties of the microbial-derived flavonoid metabolites 3,4-dihydroxyphenylacetic acid (DHPAA), 2,3-dihydroxybenzoic acid (DHBA) and 3-hydroxyphenylpropionic acid (HPPA). To this end, we tested their ability to influence beta cell function and to protect against tert-butyl hydroperoxide-induced beta cell toxicity. DHPAA and HPPA were able to potentiate glucose-stimulated insulin secretion (GSIS) in a beta cell line INS-1E and in rat pancreatic islets. Moreover, pre-treatment of cells with both compounds protected against beta cell dysfunction and death induced by the pro-oxidant. Finally, experiments with pharmacological inhibitors indicate that these effects were mediated by the activation of protein kinase C and the extracellular regulated kinases pathways. Altogether, these findings strongly suggest that the microbial-derived flavonoid metabolites DHPAA and HPPA may have anti-diabetic potential by promoting survival and function of pancreatic beta cells.

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

    SciTech Connect

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

    2010-04-01

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

  1. p16(Ink4a)-induced senescence of pancreatic beta cells enhances insulin secretion.

    PubMed

    Helman, Aharon; Klochendler, Agnes; Azazmeh, Narmen; Gabai, Yael; Horwitz, Elad; Anzi, Shira; Swisa, Avital; Condiotti, Reba; Granit, Roy Z; Nevo, Yuval; Fixler, Yaakov; Shreibman, Dorin; Zamir, Amit; Tornovsky-Babeay, Sharona; Dai, Chunhua; Glaser, Benjamin; Powers, Alvin C; Shapiro, A M James; Magnuson, Mark A; Dor, Yuval; Ben-Porath, Ittai

    2016-04-01

    Cellular senescence is thought to contribute to age-associated deterioration of tissue physiology. The senescence effector p16(Ink4a) is expressed in pancreatic beta cells during aging and limits their proliferative potential; however, its effects on beta cell function are poorly characterized. We found that beta cell-specific activation of p16(Ink4a) in transgenic mice enhances glucose-stimulated insulin secretion (GSIS). In mice with diabetes, this leads to improved glucose homeostasis, providing an unexpected functional benefit. Expression of p16(Ink4a) in beta cells induces hallmarks of senescence--including cell enlargement, and greater glucose uptake and mitochondrial activity--which promote increased insulin secretion. GSIS increases during the normal aging of mice and is driven by elevated p16(Ink4a) activity. We found that islets from human adults contain p16(Ink4a)-expressing senescent beta cells and that senescence induced by p16(Ink4a) in a human beta cell line increases insulin secretion in a manner dependent, in part, on the activity of the mechanistic target of rapamycin (mTOR) and the peroxisome proliferator-activated receptor (PPAR)-γ proteins. Our findings reveal a novel role for p16(Ink4a) and cellular senescence in promoting insulin secretion by beta cells and in regulating normal functional tissue maturation with age.

  2. A red-shifted photochromic sulfonylurea for the remote control of pancreatic beta cell function.

    PubMed

    Broichhagen, J; Frank, J A; Johnston, N R; Mitchell, R K; Šmid, K; Marchetti, P; Bugliani, M; Rutter, G A; Trauner, D; Hodson, D J

    2015-04-07

    Azobenzene photoresponsive elements can be installed on sulfonylureas, yielding optical control over pancreatic beta cell function and insulin release. An obstacle to such photopharmacological approaches remains the use of ultraviolet-blue illumination. Herein, we synthesize and test a novel yellow light-activated sulfonylurea based on a heterocyclic azobenzene bearing a push-pull system.

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

    PubMed

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

    2016-05-05

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

  4. Pathway to diabetes through attenuation of pancreatic beta cell glycosylation and glucose transport.

    PubMed

    Ohtsubo, Kazuaki; Chen, Mark Z; Olefsky, Jerrold M; Marth, Jamey D

    2011-08-14

    A connection between diet, obesity and diabetes exists in multiple species and is the basis of an escalating human health problem. The factors responsible provoke both insulin resistance and pancreatic beta cell dysfunction but remain to be fully identified. We report a combination of molecular events in human and mouse pancreatic beta cells, induced by elevated levels of free fatty acids or by administration of a high-fat diet with associated obesity, that comprise a pathogenic pathway to diabetes. Elevated concentrations of free fatty acids caused nuclear exclusion and reduced expression of the transcription factors FOXA2 and HNF1A in beta cells. This resulted in a deficit of GnT-4a glycosyltransferase expression in beta cells that produced signs of metabolic disease, including hyperglycemia, impaired glucose tolerance, hyperinsulinemia, hepatic steatosis and diminished insulin action in muscle and adipose tissues. Protection from disease was conferred by enforced beta cell-specific GnT-4a protein glycosylation and involved the maintenance of glucose transporter expression and the preservation of glucose transport. We observed that this pathogenic process was active in human islet cells obtained from donors with type 2 diabetes; thus, illuminating a pathway to disease implicated in the diet- and obesity-associated component of type 2 diabetes mellitus.

  5. VEGF-A: the inductive angiogenic factor for development, regeneration and function of pancreatic beta cells.

    PubMed

    Lui, Kathy O

    2014-01-01

    The heart is the first organ to form during development in vertebrates, and many organs start to develop adjacent to the cardiovascular system. Endothelial cells (ECs) form the inner cell lining of blood vessels and represent the major cell type that interacts with developing organs including the pancreas. ECs receive signals from the developing pancreas to grow and, at the same time, release signals to determine cell-fate specification, morphogenesis and function of the pancreas. In addition to promoting survival of pancreatic islets, in this review, we discuss the role of the vascular niche and angiogenic factors, particularly VEGFA, during pancreatic beta cell development, regeneration and pathophysiological progression of diabetes. Nevertheless, unraveling the molecular signals involved in pancreatic beta cell development and regeneration may shed light into novel drug development to treat diabetes.

  6. DJ-1 Protects Pancreatic Beta Cells from Cytokine- and Streptozotocin-Mediated Cell Death.

    PubMed

    Jain, Deepak; Weber, Gesine; Eberhard, Daniel; Mehana, Amir E; Eglinger, Jan; Welters, Alena; Bartosinska, Barbara; Jeruschke, Kay; Weiss, Jürgen; Päth, Günter; Ariga, Hiroyoshi; Seufert, Jochen; Lammert, Eckhard

    2015-01-01

    A hallmark feature of type 1 and type 2 diabetes mellitus is the progressive dysfunction and loss of insulin-producing pancreatic beta cells, and inflammatory cytokines are known to trigger beta cell death. Here we asked whether the anti-oxidant protein DJ-1 encoded by the Parkinson's disease gene PARK7 protects islet cells from cytokine- and streptozotocin-mediated cell death. Wild type and DJ-1 knockout mice (KO) were treated with multiple low doses of streptozotocin (MLDS) to induce inflammatory beta cell stress and cell death. Subsequently, glucose tolerance tests were performed, and plasma insulin as well as fasting and random blood glucose concentrations were monitored. Mitochondrial morphology and number of insulin granules were quantified in beta cells. Moreover, islet cell damage was determined in vitro after streptozotocin and cytokine treatment of isolated wild type and DJ-1 KO islets using calcein AM/ethidium homodimer-1 staining and TUNEL staining. Compared to wild type mice, DJ-1 KO mice became diabetic following MLDS treatment. Insulin concentrations were substantially reduced, and fasting blood glucose concentrations were significantly higher in MLDS-treated DJ-1 KO mice compared to equally treated wild type mice. Rates of beta cell apoptosis upon MLDS treatment were twofold higher in DJ-1 KO mice compared to wild type mice, and in vitro inflammatory cytokines led to twice as much beta cell death in pancreatic islets from DJ-1 KO mice versus those of wild type mice. In conclusion, this study identified the anti-oxidant protein DJ-1 as being capable of protecting pancreatic islet cells from cell death induced by an inflammatory and cytotoxic setting.

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

    SciTech Connect

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

    2011-09-02

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

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

    SciTech Connect

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

    2015-06-19

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

  9. An octamer motif is required for activation of the inducible nitric oxide synthase promoter in pancreatic beta-cells.

    PubMed

    Darville, Martine I; Terryn, Sara; Eizirik, Décio L

    2004-03-01

    Nitric oxide, generated by the inducible form of nitric oxide synthase (iNOS), is a potential mediator of cytokine-induced beta-cell dysfunction in type 1 diabetes mellitus. We have previously shown that cytokine-induced iNOS expression is cycloheximide (CHX) sensitive and requires nuclear factor-kappa B (NF-kappa B) activation. In the present study, we show that an octamer motif located 20 bp downstream of the proximal NF-kappa B binding site in the rat iNOS promoter is critical for IL-1 beta and interferon-gamma induction of promoter activity in rat primary beta-cells and insulin-producing RINm5F cells. In gel shift assays, the octamer motif bound constitutively the transcription factor Oct1. Neither Oct1 nor NF-kappa B binding activities were blocked by CHX, suggesting that other factor(s) synthesized in response to IL-1 beta contribute to iNOS promoter induction. The high mobility group (HMG)-I(Y) protein also bound the proximal iNOS promoter region. HMG-I(Y) binding was decreased in cells treated with CHX and HMG-I(Y) silencing by RNA interference reduced IL-1 beta-induced iNOS promoter activity. These results suggest that Oct1, NF-kappa B, and HMG-I(Y) cooperate for transactivation of the iNOS promoter in pancreatic beta-cells.

  10. Increased pancreatic beta-cell apoptosis following fetal and neonatal exposure to nicotine is mediated via the mitochondria.

    PubMed

    Bruin, Jennifer E; Gerstein, Hertzel C; Morrison, Katherine M; Holloway, Alison C

    2008-06-01

    In Canada, nicotine replacement therapy is recommended as a safe smoking cessation aid for pregnant women. However, we have shown in an animal model that fetal and neonatal nicotine exposure causes increased beta-cell apoptosis and loss of beta-cell mass, which leads to the development of postnatal dysglycemia and obesity. The goal of this study was to determine whether the observed beta-cell apoptosis is mediated via the mitochondrial and/or death receptor pathway. Female Wistar rats were given saline (control) or nicotine bitartrate (1 mg/kg/day) via sc injection for 2 weeks prior to mating until weaning (postnatal day 21). At weaning, pancreas tissue was collected for Western blotting, electron microscopy (EM), and immunohistochemistry. Key markers of each apoptotic pathway were examined in whole pancreas homogenates and mitochondrial/cytosolic pancreas fractions. In the death receptor pathway, Fas and soluble Fas ligand (FasL) protein were significantly increased in the nicotine-exposed offspring compared to control animals; there was no difference in the ratio of inactive/active caspase-8 or membrane-bound FasL expression. In the mitochondrial pathway, there was a significant increase in the ratio of Bcl2/Bax, Bax translocation to the mitochondria, cytochrome c release to the cytosol, and the ratio of active/inactive caspase-3 in nicotine-exposed offspring relative to control animals. Furthermore, increased mitochondrial swelling was observed by EM in the pancreatic beta cells of nicotine-exposed offspring. Taken together, these data suggest that beta-cell apoptosis following developmental nicotine exposure is mediated via the mitochondria.

  11. Hypothyroidism in utero stimulates pancreatic beta cell proliferation and hyperinsulinaemia in the ovine fetus during late gestation.

    PubMed

    Harris, Shelley E; De Blasio, Miles J; Davis, Melissa A; Kelly, Amy C; Davenport, Hailey M; Wooding, F B Peter; Blache, Dominique; Meredith, David; Anderson, Miranda; Fowden, Abigail L; Limesand, Sean W; Forhead, Alison J

    2017-01-31

    Development of pancreatic beta cell mass before birth is essential for normal growth of the fetus and for long-term control of carbohydrate metabolism in postnatal life. Thyroid hormones are also important regulators of fetal growth, and the present study tested the hypotheses that thyroid hormones promote beta cell proliferation in the fetal ovine pancreatic islets, and that growth retardation in hypothyroid fetal sheep is associated with reductions in pancreatic beta cell mass and circulating insulin concentration in utero. Organ growth and pancreatic islet cell proliferation and mass were examined in sheep fetuses following removal of the thyroid gland in utero. The effects of T3 , insulin and leptin on beta cell proliferation rates were determined in isolated fetal ovine pancreatic islets in vitro. Hypothyroidism in the sheep fetus resulted in an asymmetric pattern of organ growth, pancreatic beta cell hyperplasia, and elevated plasma insulin and leptin concentrations. In pancreatic islets isolated from intact fetal sheep, beta cell proliferation in vitro was reduced by T3 in a dose-dependent manner and increased by insulin at high concentrations only. Leptin induced a bimodal response whereby beta cell proliferation was suppressed at the lowest, and increased at the highest, concentrations. Therefore, proliferation of beta cells isolated from the ovine fetal pancreas is sensitive to physiological concentrations of T3 , insulin and leptin. Alterations in these hormones may be responsible for the increased beta cell proliferation and mass observed in the hypothyroid sheep fetus and may have consequences for pancreatic function in later life. This article is protected by copyright. All rights reserved.

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

    PubMed

    Domínguez-Bendala, Juan; Ricordi, Camillo

    2012-12-21

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

  13. [New aspects of pancreatic beta cell functions and their possible therapeutic applications].

    PubMed

    Tiedge, M

    2006-12-01

    Using the metabolic stimulus-secretion coupling of pancreatic beta cells as an example, this review illustrates how new strategies in the treatment of type 2 diabetes mellitus can be developed from the results of basic research. Metabolic stimulus-secretion coupling presupposes the metabolizing of those stimuli of insulin secretion that have the properties of nutritional substances. Changes in the ATP/ADP ratio within the beta cells will then trigger the release of insulin granules from them. Glucokinase, a glucose phosphorylating enzyme, functions as a metabolic glucose sensor, which couples changes in physiological glucose concentration in the pancreatic beta cells and in the liver to the intermediary metabolism, i.e. glycolysis, the citrate cycle and respiratory-chain phosphorylation. In this way insulin secretion and hepatic metabolism are positively influenced. Several pharmaceutical companies (Roche, Merck, Astra-Zeneca, Lilly) have recently developed first examples of glucokinase-activating compounds and demonstrated in animal models their efficacy in the treatment of type 2 diabetes mellitus. These glucokinase activators prevent glucokinase from changing into a catalytically inactive structure. They also increase glucose affinity of the enzyme and stabilize a catalytically active form of glucokinase proteins. In this way glucokinase activators increase glucose-induced insulin secretion and inhibit hepatic glucogenesis. Glucokinase activators are an interesting innovation in the future treatment of type 2 diabetes, because their action on beta cells and the liver is caused by changes in blood glucose concentration.

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

    PubMed

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

    2016-09-01

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

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

    SciTech Connect

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

    2009-11-20

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

  16. Age-Related Impairment of Pancreatic Beta-Cell Function: Pathophysiological and Cellular Mechanisms

    PubMed Central

    De Tata, Vincenzo

    2014-01-01

    The incidence of type 2 diabetes significantly increases with age. The relevance of this association is dramatically magnified by the concomitant global aging of the population, but the underlying mechanisms remain to be fully elucidated. Here, some recent advances in this field are reviewed at the level of both the pathophysiology of glucose homeostasis and the cellular senescence of pancreatic islets. Overall, recent results highlight the crucial role of beta-cell dysfunction in the age-related impairment of pancreatic endocrine function and delineate the possibility of new original therapeutic interventions. PMID:25232350

  17. Protective effect of berberine on beta cells in streptozotocin- and high-carbohydrate/high-fat diet-induced diabetic rats.

    PubMed

    Zhou, Jiyin; Zhou, Shiwen; Tang, Jianlin; Zhang, Kebin; Guang, Lixia; Huang, Yongping; Xu, Ying; Ying, Yi; Zhang, Le; Li, Dandan

    2009-03-15

    Oxidative stress in diabetes coexists with a reduction in the antioxidant status, which can further increase the deleterious effects of free radicals. Berberine is one of the main alkaloids of Rhizoma coptidis which has been used to treat diabetes for more than 1400 years in China. The present study was designed to evaluate the protective effects of berberine against beta cell damage and antioxidant of pancreas in diabetic rats. Diabetic rats with hyperlipidemia were induced by intraperitoneally injection 35 mg/kg streptozotocin and a high-carbohydrate/high-fat diet. Rats were divided into 7 groups at the end of week 16: untreated control, untreated diabetic, 75, 150, 300 mg/kg berberine-treated diabetic, 100 mg/kg fenofibrate-treated, and 4 mg/kg rosiglitazone-treated. After 16 weeks treatment, serum insulin level, insulin expression in pancreas, and malonaldehyde content, superoxide dismutase activity in pancreatic homogenate were assayed. Pancreas was examined by hematoxylin/eosin staining and transmission electron microscope. Pancreas to body weight ratio, insulin level, insulin sensitivity index, malonaldehyde content and superoxide dismutase activity were altered in diabetic rats, and were near control levels treated with 150, 300 mg/kg berberine. Mitochondrial vacuolization and swelling, dilatation of the endoplasmic reticulum were observed in beta cells of diabetic rats. The pancreatic islet area atrophied and secretory granules of beta cells decreased in diabetic rats. Slight pathological changes existed in beta cells of 150, 300 mg/kg berberine-treated diabetic pancreas. These findings suggest that berberine has protective effect for diabetes through increasing insulin expression, beta cell regeneration, antioxidant enzyme activity and decreasing lipid peroxidation.

  18. T-cell tolerance toward a transgenic beta-cell antigen and transcription of endogenous pancreatic genes in thymus.

    PubMed Central

    Jolicoeur, C; Hanahan, D; Smith, K M

    1994-01-01

    Transgenic mice expressing T antigen (Tag) in pancreatic beta cells establish systemic tolerance toward this self-protein. The self-tolerance in two families of rat insulin promoter (RIP)-Tag mice, expressing different levels of Tag protein, has been characterized. These mice have impaired antibody responses to Tag, show diminished Tag-specific T-cell proliferation, and evidence an inability to generate Tag-specific cytotoxic T cells. The existence of systemic tolerance toward a beta-cell-specific protein motivated examination of transgene expression in the thymus. Indeed, low levels of Tag mRNA were detected intrathymically. Remarkably, this expression is a valid property of the insulin gene regulatory region, since insulin RNA was also expressed in the thymus of nontransgenic mice. RNA for other pancreatic genes was also detected in the thymus, thus raising the possibility that many tissue-specific genes could be expressed intrathymically during immunological development and induction of self-tolerance. These results raise important questions for future research into the role of the thymus in tolerance induction toward so-called tissue-specific antigens. Images PMID:8022837

  19. Skin deep: from dermal fibroblasts to pancreatic beta cells.

    PubMed

    Manzar, Gohar S; Kim, Eun-Mi; Rotti, Pavana; Zavazava, Nicholas

    2014-08-01

    Type I diabetes (T1D) is a chronic autoimmune disease caused by pancreatic β-cell destruction induced by autoantibodies and autoreactive T cells. After significant reduction of the β-cell mass, diabetes sets in and can cause significant complications. It is estimated that more than 3 million Americans have T1D, and its prevalence among young individuals is progressively rising; however, the reasons for this increase are not known. Islet transplantation is recognized as the ultimate cure for T1D, but unfortunately, the severe scarcity of available islets makes it necessary to establish alternative sources of β-cells. Our lab seeks to establish human-induced pluripotent stem cells as an unlimited, novel source of insulin-producing cells (IPCs) that are patient-specific, obviating the requirement for immunosuppression. Although several reports have emerged demonstrating successful derivation of IPCs from human pluripotent stem cells, the efficiencies of derivation are inadequate and these IPCs do not respond to glucose stimulation in vitro. We reasoned that the use of a growth factor sequestering bioscaffold and promotion of cell-cell signaling through 3D clustering would enhance the generation of functionally superior IPCs compared to those derived by 2D differentiation. Here, we discuss a novel 3D platform for the generation of highly efficient human IPCs.

  20. In vitro reprogramming of pancreatic alpha cells towards a beta cell phenotype following ectopic HNF4α expression.

    PubMed

    Sangan, Caroline B; Jover, Ramiro; Heimberg, Harry; Tosh, David

    2015-01-05

    There is currently a shortage of organ donors available for pancreatic beta cell transplantation into diabetic patients. An alternative source of beta cells is pre-existing pancreatic cells. While we know that beta cells can arise directly from alpha cells during pancreatic regeneration we do not understand the molecular basis for the switch in phenotype. The aim of the present study was to investigate if hepatocyte nuclear factor 4 alpha (HNF4α), a transcription factor essential for a normal beta cell phenotype, could induce the reprogramming of alpha cells towards potential beta cells. We utilised an in vitro model of pancreatic alpha cells, the murine αTC1-9 cell line. We initially characterised the αTC1-9 cell line before and following adenovirus-mediated ectopic expression of HNF4α. We analysed the phenotype at transcript and protein level and assessed its glucose-responsiveness. Ectopic HNF4α expression in the αTC1-9 cell line induced a change in morphology (1.7-fold increase in size), suppressed glucagon expression, induced key beta cell-specific markers (insulin, C-peptide, glucokinase, GLUT2 and Pax4) and pancreatic polypeptide (PP) and enabled the cells to secrete insulin in a glucose-regulated manner. In conclusion, HNF4α reprograms alpha cells to beta-like cells.

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

    SciTech Connect

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

    2009-01-16

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

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

    SciTech Connect

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

    2007-02-23

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

  3. Serum CA19-9 Level Associated with Metabolic Control and Pancreatic Beta Cell Function in Diabetic Patients

    PubMed Central

    Yu, Haoyong; Li, Ruixia; Zhang, Lei; Chen, Haibing; Bao, Yuqian; Jia, Weiping

    2012-01-01

    CA19-9 is a tumor-associated antigen. It is also a marker of pancreatic tissue damage that might be caused by diabetes. Long-term poor glycemic control may lead to pancreatic beta cell dysfunction which is reflected by elevated serum CA19-9 level. Intracellular cholesterol accumulation leads to islet dysfunction and impaired insulin secretion which provide a new lipotoxic model. This study firstly found total cholesterol was one of the independent contributors to CA19-9. Elevated serum CA19-9 level in diabetic patients may indicate further investigations of glycemic control, pancreatic beta cell function, and total cholesterol level. PMID:22778715

  4. Elevated miR-130a/miR130b/miR-152 expression reduces intracellular ATP levels in the pancreatic beta cell

    PubMed Central

    Ofori, Jones K.; Salunkhe, Vishal A.; Bagge, Annika; Vishnu, Neelanjan; Nagao, Mototsugu; Mulder, Hindrik; Wollheim, Claes B.; Eliasson, Lena; Esguerra, Jonathan L. S.

    2017-01-01

    MicroRNAs have emerged as important players of gene regulation with significant impact in diverse disease processes. In type-2 diabetes, in which impaired insulin secretion is a major factor in disease progression, dysregulated microRNA expression in the insulin-secreting pancreatic beta cell has been widely-implicated. Here, we show that miR-130a-3p, miR-130b-3p, and miR-152-3p levels are elevated in the pancreatic islets of hyperglycaemic donors, corroborating previous findings about their upregulation in the islets of type-2 diabetes model Goto-Kakizaki rats. We demonstrated negative regulatory effects of the three microRNAs on pyruvate dehydrogenase E1 alpha (PDHA1) and on glucokinase (GCK) proteins, which are both involved in ATP production. Consequently, we found both proteins to be downregulated in the Goto-Kakizaki rat islets, while GCK mRNA expression showed reduced trend in the islets of type-2 diabetes donors. Overexpression of any of the three microRNAs in the insulin-secreting INS-1 832/13 cell line resulted in altered dynamics of intracellular ATP/ADP ratio ultimately perturbing fundamental ATP-requiring beta cell processes such as glucose-stimulated insulin secretion, insulin biosynthesis and processing. The data further strengthen the wide-ranging influence of microRNAs in pancreatic beta cell function, and hence their potential as therapeutic targets in type-2 diabetes. PMID:28332581

  5. Pancreatic beta-cell glucokinase: closing the gap between theoretical concepts and experimental realities.

    PubMed

    Matschinsky, F M; Glaser, B; Magnuson, M A

    1998-03-01

    There remains a wide gap between theoretical concepts and experimental realities in the enzyme kinetics and biochemical genetics of the pancreatic beta-cell glucokinase-glucose sensor. It is the goal of present efforts in many laboratories to bridge this gap. This perspective intends to provide a timely review of this crucial aspect of research in glucose homeostasis. It deals briefly with some fundamentals of glucokinase enzyme kinetics, offers some pertinent biochemical genetic considerations, takes stock of the current experimental database of the field by emphasizing human studies and referring to recent mouse studies, and ventures a few extrapolations into the future of this endeavor.

  6. Beta-cell hypertrophy in fa/fa rats is associated with basal glucose hypersensitivity and reduced SNARE protein expression.

    PubMed

    Chan, C B; MacPhail, R M; Sheu, L; Wheeler, M B; Gaisano, H Y

    1999-05-01

    In normal isolated beta-cells, the response to glucose is heterogeneous and characterized by an increasing number of secretory cells as glucose concentration rises (Pipeleers DG, Kiekens R, Ling Z, Wilikens A, Schuit F: Physiologic relevance of heterogeneity in the pancreatic beta-cell population. Diabetologia 37 (Suppl. 2):S57-S64, 1994). We hypothesized that fasting hyperinsulinemia in obesity might be explained by altered beta-cell heterogeneity of signal transduction mechanisms, possibly involving exocytotic proteins. Insulin secretion from individual beta-cells sorted according to the size of the islet donor (<125 microm, >250 microm, and intermediate diameter) was measured by reverse hemolytic plaque assay. Beta-cells from fa/fa rats were hypertrophied 25-40%, independent of donor islet size. This was accompanied by an increased proportion of secretory cells (recruitment) at 5.5-11.0 mmol/l glucose, increased secretion per cell at 2.8 mmol/l glucose, and decreased insulin content after acute glucose exposure without an increase in secretion per cell. Decreased expression of exocytotic (soluble N-ethylmaleimide-sensitive fusion protein receptor [SNARE]) proteins, vesicle-associated membrane protein isoform 2 (VAMP-2), synaptosomal protein of 25 kDa (SNAP-25), and syntaxin-1 and -2 in fa/fa beta-cells may contribute to the failure to sustain excessive plaque size at higher glucose concentrations. Fasting hyperinsulinemia may be maintained by increased recruitment and an exaggerated secretory response in all fa-derived islet populations. Glucose regulates beta-cell responsiveness in the short term, and these effects may involve altered expression of SNARE proteins.

  7. Calcium co-regulates oxidative metabolism and ATP synthase-dependent respiration in pancreatic beta cells.

    PubMed

    De Marchi, Umberto; Thevenet, Jonathan; Hermant, Aurelie; Dioum, Elhadji; Wiederkehr, Andreas

    2014-03-28

    Mitochondrial energy metabolism is essential for glucose-induced calcium signaling and, therefore, insulin granule exocytosis in pancreatic beta cells. Calcium signals are sensed by mitochondria acting in concert with mitochondrial substrates for the full activation of the organelle. Here we have studied glucose-induced calcium signaling and energy metabolism in INS-1E insulinoma cells and human islet beta cells. In insulin secreting cells a surprisingly large fraction of total respiration under resting conditions is ATP synthase-independent. We observe that ATP synthase-dependent respiration is markedly increased after glucose stimulation. Glucose also causes a very rapid elevation of oxidative metabolism as was followed by NAD(P)H autofluorescence. However, neither the rate of the glucose-induced increase nor the new steady-state NAD(P)H levels are significantly affected by calcium. Our findings challenge the current view, which has focused mainly on calcium-sensitive dehydrogenases as the target for the activation of mitochondrial energy metabolism. We propose a model of tight calcium-dependent regulation of oxidative metabolism and ATP synthase-dependent respiration in beta cell mitochondria. Coordinated activation of matrix dehydrogenases and respiratory chain activity by calcium allows the respiratory rate to change severalfold with only small or no alterations of the NAD(P)H/NAD(P)(+) ratio.

  8. MDA5 and PTPN2, two candidate genes for type 1 diabetes, modify pancreatic beta-cell responses to the viral by-product double-stranded RNA.

    PubMed

    Colli, Maikel L; Moore, Fabrice; Gurzov, Esteban N; Ortis, Fernanda; Eizirik, Decio L

    2010-01-01

    beta-Cell destruction in type 1 diabetes (T1D) is at least in part consequence of a 'dialog' between beta-cells and immune system. This dialog may be affected by the individual's genetic background. We presently evaluated whether modulation of MDA5 and PTPN2, two candidate genes for T1D, affects beta-cell responses to double-stranded RNA (dsRNA), a by-product of viral replication. These genes were selected following comparison between known candidate genes for T1D and genes expressed in pancreatic beta-cells, as identified in previous array analysis. INS-1E cells and primary fluorescence-activated cell sorting-purified rat beta-cells were transfected with small interference RNAs (siRNAs) targeting MDA5 or PTPN2 and subsequently exposed to intracellular synthetic dsRNA (polyinosinic-polycitidilic acid-PIC). Real-time RT-PCR, western blot and viability assays were performed to characterize gene/protein expression and viability. PIC increased MDA5 and PTPN2 mRNA expression, which was inhibited by the specific siRNAs. PIC triggered apoptosis in INS-1E and primary beta-cells and this was augmented by PTPN2 knockdown (KD), although inhibition of MDA5 did not modify PIC-induced apoptosis. In contrast, MDA5 silencing decreased PIC-induced cytokine and chemokine expression, although inhibition of PTPN2 induced minor or no changes in these inflammatory mediators. These findings indicate that changes in MDA5 and PTPN2 expression modify beta-cell responses to dsRNA. MDA5 regulates inflammatory signals, whereas PTPN2 may function as a defence mechanism against pro-apoptotic signals generated by dsRNA. These two candidate genes for T1D may thus modulate beta-cell apoptosis and/or local release of inflammatory mediators in the course of a viral infection by acting, at least in part, at the pancreatic beta-cell level.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

  11. Retinoic acid promotes the generation of pancreatic endocrine progenitor cells and their further differentiation into beta-cells.

    PubMed

    Oström, Maria; Loffler, Kelly A; Edfalk, Sara; Selander, Lars; Dahl, Ulf; Ricordi, Camillo; Jeon, Jongmin; Correa-Medina, Mayrin; Diez, Juan; Edlund, Helena

    2008-07-30

    The identification of secreted factors that can selectively stimulate the generation of insulin producing beta-cells from stem and/or progenitor cells represent a significant step in the development of stem cell-based beta-cell replacement therapy. By elucidating the molecular mechanisms that regulate the generation of beta-cells during normal pancreatic development such putative factors may be identified. In the mouse, beta-cells increase markedly in numbers from embryonic day (e) 14.5 and onwards, but the extra-cellular signal(s) that promotes the selective generation of beta-cells at these stages remains to be identified. Here we show that the retinoic acid (RA) synthesizing enzyme Raldh1 is expressed in developing mouse and human pancreas at stages when beta-cells are generated. We also provide evidence that RA induces the generation of Ngn3(+) endocrine progenitor cells and stimulates their further differentiation into beta-cells by activating a program of cell differentiation that recapitulates the normal temporal program of beta-cell differentiation.

  12. Characterization of Acyl-CoA synthetase isoforms in pancreatic beta cells: Gene silencing shows participation of ACSL3 and ACSL4 in insulin secretion.

    PubMed

    Ansari, Israr-Ul H; Longacre, Melissa J; Stoker, Scott W; Kendrick, Mindy A; O'Neill, Lucas M; Zitur, Laura J; Fernandez, Luis A; Ntambi, James M; MacDonald, Michael J

    2017-03-15

    Long-chain acyl-CoA synthetases (ACSLs) convert fatty acids to fatty acyl-CoAs to regulate various physiologic processes. We characterized the ACSL isoforms in a cell line of homogeneous rat beta cells (INS-1 832/13 cells) and human pancreatic islets. ACSL4 and ACSL3 proteins were present in the beta cells and human and rat pancreatic islets and concentrated in insulin secretory granules and less in mitochondria and negligible in other intracellular organelles. ACSL1 and ACSL6 proteins were not seen in INS-1 832/13 cells or pancreatic islets. ACSL5 protein was seen only in INS-1 832/13 cells. With shRNA-mediated gene silencing we developed stable ACSL knockdown cell lines from INS-1 832/13 cells. Glucose-stimulated insulin release was inhibited ∼50% with ACSL4 and ACSL3 knockdown and unaffected in cell lines with knockdown of ACSL5, ACLS6 and ACSL1. Lentivirus shRNA-mediated gene silencing of ACSL4 and ACSL3 in human pancreatic islets inhibited glucose-stimulated insulin release. ACSL4 and ACSL3 knockdown cells showed inhibition of ACSL enzyme activity more with arachidonate than with palmitate as a substrate, consistent with their preference for unsaturated fatty acids as substrates. ACSL4 knockdown changed the patterns of fatty acids in phosphatidylserines and phosphatidylethanolamines. The results show the involvement of ACLS4 and ACLS3 in insulin secretion.

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

    SciTech Connect

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

    2012-10-26

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

  14. Long-term persistence and development of induced pancreatic beta cells generated by lineage conversion of acinar cells.

    PubMed

    Li, Weida; Cavelti-Weder, Claudia; Zhang, Yingying; Zhang, Yinying; Clement, Kendell; Donovan, Scott; Gonzalez, Gabriel; Zhu, Jiang; Stemann, Marianne; Xu, Ke; Hashimoto, Tatsu; Yamada, Takatsugu; Nakanishi, Mio; Zhang, Yuemei; Zeng, Samuel; Gifford, David; Meissner, Alexander; Weir, Gordon; Zhou, Qiao

    2014-12-01

    Direct lineage conversion is a promising approach to generate therapeutically important cell types for disease modeling and tissue repair. However, the survival and function of lineage-reprogrammed cells in vivo over the long term has not been examined. Here, using an improved method for in vivo conversion of adult mouse pancreatic acinar cells toward beta cells, we show that induced beta cells persist for up to 13 months (the length of the experiment), form pancreatic islet-like structures and support normoglycemia in diabetic mice. Detailed molecular analyses of induced beta cells over 7 months reveal that global DNA methylation changes occur within 10 d, whereas the transcriptional network evolves over 2 months to resemble that of endogenous beta cells and remains stable thereafter. Progressive gain of beta-cell function occurs over 7 months, as measured by glucose-regulated insulin release and suppression of hyperglycemia. These studies demonstrate that lineage-reprogrammed cells persist for >1 year and undergo epigenetic, transcriptional, anatomical and functional development toward a beta-cell phenotype.

  15. An AP-3-dependent mechanism drives synaptic-like microvesicle biogenesis in pancreatic islet beta-cells.

    PubMed

    Suckow, Arthur T; Craige, Branch; Faundez, Victor; Cain, William J; Chessler, Steven D

    2010-07-01

    Pancreatic islet beta-cells contain synaptic-like microvesicles (SLMVs). The origin, trafficking, and role of these SLMVs are poorly understood. In neurons, synaptic vesicle (SV) biogenesis is mediated by two different cytosolic adaptor protein complexes, a ubiquitous AP-2 complex and the neuron-specific AP-3B complex. Mice lacking AP-3B subunits exhibit impaired GABAergic (inhibitory) neurotransmission and reduced neuronal vesicular GABA transporter (VGAT) content. Since beta-cell maturation and exocytotic function seem to parallel that of the inhibitory synapse, we predicted that AP-3B-associated vesicles would be present in beta-cells. Here, we test the hypothesis that AP-3B is expressed in islets and mediates beta-cell SLMV biogenesis. A secondary aim was to test whether the sedimentation properties of INS-1 beta-cell microvesicles are identical to those of bona fide SLMVs isolated from PC12 cells. Our results show that the two neuron-specific AP-3 subunits beta3B and mu3B are expressed in beta-cells, the first time these proteins have been found to be expressed outside the nervous system. We found that beta-cell SLMVs share the same sedimentation properties as PC12 SLMVs and contain SV proteins that sort specifically to AP-3B-associated vesicles in the brain. Brefeldin A, a drug that interferes with AP-3-mediated SV biogenesis, inhibits the delivery of AP-3 cargoes to beta-cell SLMVs. Consistent with a role for AP-3 in the biogenesis of GABAergic SLMV in beta-cells, INS-1 cell VGAT content decreases upon inhibition of AP-3 delta-subunit expression. Our findings suggest that beta-cells and neurons share molecules and mechanisms important for mediating the neuron-specific membrane trafficking pathways that underlie synaptic vesicle formation.

  16. EX4 stabilizes and activates Nrf2 via PKCδ, contributing to the prevention of oxidative stress-induced pancreatic beta cell damage.

    PubMed

    Kim, Mi-Hwi; Kim, Eung-Hwi; Jung, Hye Seung; Yang, Dongki; Park, Eun-Young; Jun, Hee-Sook

    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 H2O2. 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.

  17. Protective effects of St. John's wort extract and its component hyperforin against cytokine-induced cytotoxicity in a pancreatic beta-cell line.

    PubMed

    Menegazzi, Marta; Novelli, Michela; Beffy, Pascale; D'Aleo, Valentina; Tedeschi, Elisa; Lupi, Roberto; Zoratti, Elisa; Marchetti, Piero; Suzuki, Hisanori; Masiello, Pellegrino

    2008-01-01

    In both type 1 and type 2 diabetes, increased production of cytokines on autoimmune or metabolic basis is supposed to trigger an inflammatory process leading to dysfunction and death of pancreatic beta-cells. Therefore, anti-inflammatory pharmacological approaches aimed at blocking cytokine signalling pathways and consequent cytotoxicity in beta-cells are highly advisable. Based on previous evidence of cytokine antagonistic effects in other cell types, we explored the protective action of Hypericum perforatum (St-John's-wort) extract and its component hyperforin against cytokine-induced functional impairment and apoptosis in the INS-1E beta-cell line, searching for the underlying mechanisms. The results showed that either St-John's-wort extract or hyperforin (at 1-3 microM) prevented cytokine-induced impairment in glucose-stimulated insulin secretion and protected cells against apoptosis in a dose-dependent fashion. Inducible-NO-synthase expression was also potently hindered by the vegetal compounds. Interestingly, cytokine-induced activations of the signal-transducer-and-activator-of-transcription-1 (STAT-1) and the nuclear-factor-kappaB (NF-kappaB) were both down-regulated by SJW extract or HPF (range 0.5-5 microM) when evaluated by electrophoretic-mobility-shift-assay. Other transcription factors (CBF-1, SP-1) were unaffected. Components of SJW extract other than HPF were much less effective in down-regulating cytokine signalling. Significantly, inhibition of cytokine-elicited STAT-1 and NF-kappaB activation was confirmed in isolated rat and human islets incubated in the presence of these vegetal compounds. In conclusion, St-John's-wort extract and hyperforin are non-peptidyl compounds which, at low concentrations, target key mechanisms of cytokine-induced beta-cell injury, thereby improving beta-cell function and survival. Thus, they are potentially valuable for the prevention or limitation of beta-cell loss in diabetes.

  18. Potassium permeability activated by intracellular calcium ion concentration in the pancreatic beta-cell.

    PubMed Central

    Atwater, I; Dawson, C M; Ribalet, B; Rojas, E

    1979-01-01

    1. Membrane potentials and input resistance were measured in beta-cells from mouse pancreatic islets of Langerhans in a study designed to assess the role of a K permeability specifically blocked by quinine or quinidine and activated by intracellular calcium ion concentration ([Ca2+])i-activated PK). 2. Addition of 100 microM-quinine to the perifusion medium resulted in a 10--30 mV depolarization of the membrane and an increase in the input resistance of ca. 4.10(7) omega. 3. In the absence of glucose, 100 microM-quinine induced electrical activity. 4. In the presence of glucose, 100 microM-quinine abolished the burst pattern of electrical activity and very much reduced the graded response of spike frequency normally seen with different concentrations of glucose. 5. Addition of mitochondrial inhibitors, KCN, NaN3, DNP, CCCP, FCCP, to the perifusion medium containing glucose rapidly hyperpolarized the beta-cell membrane, inducing a concomitant decrease in input resistance. 6. In the presence of glucose, these mitochondrial inhibitors reversibly blocked electrical activity; upon removal of the inhibitor, recovery of electrical activity followed a biphasic pattern. 7. The effects of mitochondrial inhibitors were partially reversed by 100 microM-quinine. 8. It is proposed that the membrane potential of the beta-cell in the absence of glucose is predominantly controlled by the [Ca2+]i-activated PK. It is further suggested that this permeability to K controls the level for glucose stimulation and leads to the generation of the burst pattern. PMID:381636

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  20. Emergence of organized bursting in clusters of pancreatic beta-cells by channel sharing.

    PubMed Central

    Sherman, A; Rinzel, J; Keizer, J

    1988-01-01

    Pancreatic beta-cells in an intact Islet of Langerhans exhibit bursting electrical behavior. The Chay-Keizer model describes this using a calcium-activated potassium (K-Ca) channel, but cannot account for the irregular spiking of isolated beta-cells. Atwater I., L. Rosario, and E. Rojas, Cell Calcium. 4:451-461, proposed that the K-Ca channels, which are rarely open, are shared by several cells. This suggests that the chaotic behavior of isolated cells is stochastic. We have revised the Chay-Keizer model to incorporate voltage clamp data of Rorsman and Trube and extended it to include stochastic K-Ca channels. This model can describe the behavior of single cells, as well as that of clusters of cells tightly coupled by gap junctions. As the size of the clusters is increased, the electrical activity shows a transition from chaotic spiking to regular bursting. Although the model of coupling is over-simplified, the simulations lend support to the hypothesis that bursting is the result of channel sharing. PMID:2850029

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

    PubMed

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

    2008-12-01

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

  2. Immunohistochemical evidence of Orexin-A in the pancreatic beta cells of domestic animals.

    PubMed

    Dall'Aglio, C; Pedini, V; Scocco, P; Boiti, C; Ceccarelli, P

    2010-10-01

    A large body of information proves that Orexin-A is present in the pancreatic endocrine cells of humans and laboratory animals; more detailed studies identify Orexin-A-immunopositive cells as beta cells. Because no data have been reported on the pancreas of domestic animals, we investigated the presence and the distribution of cells containing Orexin-A in the pancreas of cattle, sheep and pigs by means of immunohistochemical techniques. Using a polyclonal antibody against Orexin-A, the immunopositive reaction was identified in the cytoplasm of many insular cells in the three species studied. Double immunohistochemical staining, using a polyclonal anti-insulin antibody, showed that Orexin-A is co-expressed with insulin. Our results, besides showing the presence of Orexin-A in the endocrine pancreas of domestic animals, together with data present in the literature, could contribute to the understanding of complex mechanisms regulating the functionality of the endocrine pancreas in domestic animals.

  3. UCP-2 and UCP-3 Proteins Are Differentially Regulated in Pancreatic Beta-Cells

    PubMed Central

    Li, Yunfeng; Maedler, Kathrin; Shu, Luan; Haataja, Leena

    2008-01-01

    Background Increased uncoupling protein-2 (UCP-2) expression has been associated with impaired insulin secretion, whereas UCP-3 protein levels are decreased in the skeleton muscle of type-2 diabetic subjects. In the present studies we hypothesize an opposing effect of glucose on the regulation of UCP-2 and UCP-3 in pancreatic islets. Methodology Dominant negative UCP-2 and wild type UCP-3 adenoviruses were generated, and insulin release by transduced human islets was measured. UCP-2 and UCP-3 mRNA levels were determined using quantitative PCR. UCP-2 and UCP-3 protein expression was investigated in human islets cultured in the presence of different glucose concentrations. Human pancreatic sections were analyzed for subcellular localization of UCP-3 using immunohistochemistry. Principal Findings Dominant negative UCP-2 expression in human islets increased insulin secretion compared to control islets (p<0.05). UCP-3 mRNA is expressed in human islets, but the relative abundance of UCP-2 mRNA was 8.1-fold higher (p<0.05). Immunohistochemical analysis confirmed co-localization of UCP-3 protein with mitochondria in human beta-cells. UCP-2 protein expression in human islets was increased ∼2-fold after high glucose exposure, whereas UCP-3 protein expression was decreased by ∼40% (p<0.05). UCP-3 overexpression improved glucose-stimulated insulin secretion. Conclusions UCP-2 and UCP-3 may have distinct roles in regulating beta-cell function. Increased expression of UCP-2 and decreased expression of UCP-3 in humans with chronic hyperglycemia may contribute to impaired glucose-stimulated insulin secretion. These data imply that mechanisms that suppress UCP-2 or mechanisms that increase UCP-3 expression and/or function are potential therapeutic targets to offset defects of insulin secretion in humans with type-2 diabetes. PMID:18167556

  4. Early peroxisome proliferator-activated receptor gamma regulated genes involved in expansion of pancreatic beta cell mass

    PubMed Central

    2011-01-01

    Background The progression towards type 2 diabetes depends on the allostatic response of pancreatic beta cells to synthesise and secrete enough insulin to compensate for insulin resistance. The endocrine pancreas is a plastic tissue able to expand or regress in response to the requirements imposed by physiological and pathophysiological states associated to insulin resistance such as pregnancy, obesity or ageing, but the mechanisms mediating beta cell mass expansion in these scenarios are not well defined. We have recently shown that ob/ob mice with genetic ablation of PPARγ2, a mouse model known as the POKO mouse failed to expand its beta cell mass. This phenotype contrasted with the appropriate expansion of the beta cell mass observed in their obese littermate ob/ob mice. Thus, comparison of these models islets particularly at early ages could provide some new insights on early PPARγ dependent transcriptional responses involved in the process of beta cell mass expansion Results Here we have investigated PPARγ dependent transcriptional responses occurring during the early stages of beta cell adaptation to insulin resistance in wild type, ob/ob, PPARγ2 KO and POKO mice. We have identified genes known to regulate both the rate of proliferation and the survival signals of beta cells. Moreover we have also identified new pathways induced in ob/ob islets that remained unchanged in POKO islets, suggesting an important role for PPARγ in maintenance/activation of mechanisms essential for the continued function of the beta cell. Conclusions Our data suggest that the expansion of beta cell mass observed in ob/ob islets is associated with the activation of an immune response that fails to occur in POKO islets. We have also indentified other PPARγ dependent differentially regulated pathways including cholesterol biosynthesis, apoptosis through TGF-β signaling and decreased oxidative phosphorylation. PMID:22208362

  5. Effect of prolonged exposure to sublethal concentrations of DDT and DDE on protein expression in human pancreatic beta cells.

    PubMed

    Pavlikova, Nela; Smetana, Pavel; Halada, Petr; Kovar, Jan

    2015-10-01

    Pollution of the environment represents one of less explored potential reasons for the worldwide epidemic of type 2 diabetes. One of the most prevalent organochlorine pollutants remains the pesticide DDT and its degradation product DDE. Despite some epidemiologic correlations between levels of DDT and DDE in human organism and the prevalence of diabetes, there is almost no information about the exact targets of these compounds inside pancreatic beta cells. To detect functional areas of pancreatic beta cells that could be affected by exposure to DDT and DDE, we analyzed changes in protein expression in the NES2Y human pancreatic beta cell line exposed to three sublethal concentrations (0.1 μM, 1 μM, 10 μM) of DDT and DDE for 1 month. Protein separation and identification was achieved using high-resolution 2D-electrophoresis, computer analysis and mass spectrometry. With these techniques, four proteins were found downregulated after exposure to 10 μM DDT: three cytoskeletal proteins (cytokeratin 8, cytokeratin 18 and actin) and one protein involved in glycolysis (alpha-enolase). Two proteins were downregulated after exposure to 10 μM DDE: cytokeratin 18 and heterogenous nuclear ribonucleoprotein H1 (HNRH1). These changes correlate with previously described effects of other stress conditions (e.g. exposure to palmitate, hyperglycemia, imidazoline derivative, and cytokines) on protein expression in pancreatic beta cells. We conclude that cytoskeletal proteins and their processing, glucose metabolism, and mRNA processing may represent targets affected by exposure to conditions hostile to pancreatic beta cells, including exposure to DDT and DDE.

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

    PubMed Central

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

    2011-01-01

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

  7. Biotin uptake by mouse and human pancreatic beta cells/islets: a regulated, lipopolysaccharide-sensitive carrier-mediated process.

    PubMed

    Ghosal, Abhisek; Sekar, Thillai V; Said, Hamid M

    2014-08-01

    Biotin is essential for the normal function of pancreatic beta cells. These cells obtain biotin from their surroundings via transport across their cell membrane. Little is known about the uptake mechanism involved, how it is regulated, and how it is affected by internal and external factors. We addressed these issues using the mouse-derived pancreatic beta-TC-6 cells and freshly isolated mouse and human primary pancreatic beta cells as models. The results showed biotin uptake by pancreatic beta-TC-6 cells occurs via a Na(+)-dependent, carrier-mediated process, that is sensitive to desthiobiotin, as well as to pantothenic acid and lipoate; the process is also saturable as a function of concentration (apparent Km = 22.24 ± 5.5 μM). These cells express the sodium-dependent multivitamin transporter (SMVT), whose knockdown (with doxycycline-inducible shRNA) led to a sever inhibition in biotin uptake. Similarly, uptake of biotin by mouse and human primary pancreatic islets is Na(+)-dependent and carrier-mediated, and both cell types express SMVT. Biotin uptake by pancreatic beta-TC-6 cells is also adaptively regulated (via transcriptional mechanism) by extracellular substrate level. Chronic treatment of pancreatic beta-TC-6 cells with bacterial lipopolysaccharides (LPS) leads to inhibition in biotin uptake. This inhibition is mediated via a Toll-Like receptor 4-mediated process and involves a decrease in membrane expression of SMVT. These findings show, for the first time, that pancreatic beta cells/islets take up biotin via a specific and regulated carrier-mediated process, and that the process is sensitive to the effect of LPS.

  8. Preservation of beta cell function after pancreatic islet autotransplantation: University of Chicago experience.

    PubMed

    Savari, Omid; Golab, Karolina; Wang, Ling-Jia; Schenck, Lindsay; Grose, Randall; Tibudan, Martin; Ramachandran, Sabarinathan; Chon, W James; Posner, Mitchell C; Millis, J Michael; Matthews, Jeffrey B; Gelrud, Andres; Witkowski, Piotr

    2015-04-01

    The aim of the study was to assess the rate of insulin independence in patients after total pancreatectomy (TP) and islet autotransplantation in our center. TP followed by islet autotransplantation was performed in 10 patients. Severe unrelenting pain associated with chronic pancreatitis was the major indication for surgery. Islets were isolated using the modified Ricordi method and infused through the portal vein. Exogenous insulin therapy was implemented for at least two months posttransplant to support islet engraftment and was subsequently weaned off, if possible. Median follow-up was 26 months (range, 2 to 60 months). Median islet yield was 158,860 islet equivalents (IEQ) (range, 40,203 to 330,472 IEQ) with an average islet yield of 2,478 IEQ/g (range, 685 to 6,002 IEQ/g) of processed pancreas. One patient developed transient partial portal vein thrombosis, which resolved without sequela. Five (50%) patients are currently off insulin with excellent glucose control and HbA1c below 6. Patients who achieved and maintained insulin independence were transplanted with significantly more islets (median, 202,291 IEQ; range, 145,000 to 330,474 IEQ) than patients who required insulin support (64,348 IEQ; range, 40,203 to 260,476 IEQ; P < 0.05). Patient body mass index and time of chronic pancreatitis prior transplant procedure did not correlate with the outcome. The remaining five patients, who require insulin support, had present C-peptide in blood and experience good glucose control without incidence of severe hypoglycemic episodes. Islet autotransplantation efficiently preserved beta cell function in selected patients with chronic pancreatitis and the outcome correlated with transplanted islet mass.

  9. Symmetric Fold/Super-Hopf Bursting, Chaos and Mixed-Mode Oscillations in Pernarowski Model of Pancreatic Beta-Cells

    NASA Astrophysics Data System (ADS)

    Fallah, Haniyeh

    Pancreatic beta-cells produce insulin to regularize the blood glucose level. Bursting is important in beta cells due to its relation to the release of insulin. Pernarowski model is a simple polynomial model of beta-cell activities indicating bursting oscillations in these cells. This paper presents bursting behaviors of symmetric type in this model. In addition, it is shown that the current system exhibits the phenomenon of period doubling cascades of canards which is a route to chaos. Canards are also observed symmetrically near folds of slow manifold which results in a chaotic transition between n and n + 1 spikes symmetric bursting. Furthermore, mixed-mode oscillations (MMOs) and combination of symmetric bursting together with MMOs are illustrated during the transition between symmetric bursting and continuous spiking.

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

    PubMed

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

    2009-01-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. Pioglitazone acutely reduces insulin secretion and causes metabolic deceleration of the pancreatic beta-cell at submaximal glucose concentrations.

    PubMed

    Lamontagne, Julien; Pepin, Emilie; Peyot, Marie-Line; Joly, Erik; Ruderman, Neil B; Poitout, Vincent; Madiraju, S R Murthy; Nolan, Christopher J; Prentki, Marc

    2009-08-01

    Thiazolidinediones (TZDs) have beneficial effects on glucose homeostasis via enhancement of insulin sensitivity and preservation of beta-cell function. How TZDs preserve beta-cells is uncertain, but it might involve direct effects via both peroxisome proliferator-activated receptor-gamma-dependent and -independent pathways. To gain insight into the independent pathway(s), we assessed the effects of short-term (beta-cell metabolism in INS 832/13 beta-cells and rat islets. Pio caused a right shift in the dose-dependence of GIIS, such that insulin release was reduced at intermediate glucose but unaffected at either basal or maximal glucose concentrations. This was associated in INS 832/13 cells with alterations in energy metabolism, characterized by reduced glucose oxidation, mitochondrial membrane polarization, and ATP levels. Pio caused AMPK phosphorylation and its action on GIIS was reversed by the AMPK inhibitor compound C. Pio also reduced palmitate esterification into complex lipids and inhibited lipolysis. As for insulin secretion, the alterations in beta-cell metabolic processes were mostly alleviated at elevated glucose. Similarly, the antidiabetic agents and AMPK activators metformin and berberine caused a right shift in the dose dependence of GIIS. In conclusion, Pio acutely reduces glucose oxidation, energy metabolism, and glycerolipid/fatty acid cycling of the beta-cell at intermediate glucose concentrations. We suggest that AMPK activation and the metabolic deceleration of the beta-cell caused by Pio contribute to its known effects to reduce hyperinsulinemia and preserve beta-cell function and act as an antidiabetic agent.

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

    SciTech Connect

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

    2010-03-15

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

  14. MST1 is a novel regulator of apoptosis in pancreatic beta-cells

    PubMed Central

    Ardestani, Amin; Khobragade, Vrushali; Yuan, Ting; Frogne, Thomas; Tao, Wufan; Oberholzer, Jose; Pattou, Francois; Conte, Julie Kerr; Maedler, Kathrin

    2014-01-01

    Apoptotic cell death is a hallmark of the loss of insulin producing beta-cells in all forms of diabetes mellitus. Current treatment fails to halt the decline in functional beta-cell mass. Strategies to prevent beta-cell apoptosis and dysfunction are urgently needed. Here, we identified Mammalian Sterile 20-like kinase 1 (MST1) as a critical regulator of apoptotic beta-cell death and function. MST1 was strongly activated in beta-cells under diabetogenic conditions and correlated with beta-cell apoptosis. MST1 specifically induced the mitochondrial-dependent pathway of apoptosis in beta-cells through up-regulation of the BH3-only protein Bim. MST1 directly phosphorylated PDX1 at Thr11, resulting in its ubiquitination, degradation and impaired insulin secretion. Mst1 deficiency completely restored normoglycemia, beta-cell function and survival in vitro and in vivo. We show MST1 as novel pro-apoptotic kinase and key mediator of apoptotic signaling and beta-cell dysfunction, which may serve as target for the development of novel therapies for diabetes. PMID:24633305

  15. Beta cell dynamics: beta cell replenishment, beta cell compensation and diabetes.

    PubMed

    Cerf, Marlon E

    2013-10-01

    Type 2 diabetes, characterized by persistent hyperglycemia, arises mostly from beta cell dysfunction and insulin resistance and remains a highly complex metabolic disease due to various stages in its pathogenesis. Glucose homeostasis is primarily regulated by insulin secretion from the beta cells in response to prevailing glycemia. Beta cell populations are dynamic as they respond to fluctuating insulin demand. Beta cell replenishment and death primarily regulate beta cell populations. Beta cells, pancreatic cells, and extra-pancreatic cells represent the three tiers for replenishing beta cells. In rodents, beta cell self-replenishment appears to be the dominant source for new beta cells supported by pancreatic cells (non-beta islet cells, acinar cells, and duct cells) and extra-pancreatic cells (liver, neural, and stem/progenitor cells). In humans, beta cell neogenesis from non-beta cells appears to be the dominant source of beta cell replenishment as limited beta cell self-replenishment occurs particularly in adulthood. Metabolic states of increased insulin demand trigger increased insulin synthesis and secretion from beta cells. Beta cells, therefore, adapt to support their physiology. Maintaining physiological beta cell populations is a strategy for targeting metabolic states of persistently increased insulin demand as in diabetes.

  16. Efficacy of natural diosgenin on cardiovascular risk, insulin secretion, and beta cells in streptozotocin (STZ)-induced diabetic rats.

    PubMed

    Kalailingam, Pazhanichamy; Kannaian, Bhuvaneswari; Tamilmani, Eevera; Kaliaperumal, Rajendran

    2014-09-15

    Costus igneus, has been prescribed for the treatment of diabetic mellitus in India for several years. The aim of this study is to investigate the effects of plant derived diosgenin on cardiovascular risk, insulin secretion, and pancreatic composition through electron microscopical studies of normal and diabetic rats. Diosgenin at a dose of 5 or 10mg/kg per body weight (bw) was orally administered as a single dose per day to diabetic induced rats for a period of 30 days. The effect of diosgenin on blood glucose, HbA1c, PT, APTT, Oxy-LDL, serum lipid profile, electron microscopical studies of pancreas, antioxidant enzymes (in liver, kidney, pancreas) and hepatoprotective enzymes in plasma and liver were measured in normal and diabetic rats. The results showed that fasting blood glucose, PT, APTT, Oxy-LDL, TC, TG, LDL, ALT, AST, ALP, glucose-6-phosphatase, fructose-1,6-bisphosphatase and LPO levels were significantly (p<0.05) increased, whereas HDL, SOD, CAT, GSH and the glycolytic enzyme glucokinase levels were significantly (p<0.05) decreased in the diabetes induced rats and these levels were significantly (p<0.05) reversed back to normal in diabetes induced rats after 30 days of treatment with diosgenin. Electron microscopical studies of the pancreas revealed that the number of beta cells and insulin granules were increased in streptozotocin (STZ) induced diabetic rats after 30 days of treatment with diosgenin. In conclusion, the data obtained from the present study strongly indicate that diosgenin has potential effects on cardiovascular risk, insulin secretion and beta cell regeneration in STZ induced diabetic rats, these results could be useful for new drug development to fight diabetes and its related cardiovascular diseases.

  17. Endoplasmic Reticulum Stress Links Oxidative Stress to Impaired Pancreatic Beta-Cell Function Caused by Human Oxidized LDL

    PubMed Central

    Favre, Dimitri; Ezanno, Hélène; Bonnefond, Amélie; Bonner, Caroline; Gmyr, Valéry; Kerr-Conte, Julie; Gauthier, Benoit R.; Widmann, Christian; Waeber, Gérard; Pattou, François; Froguel, Philippe; Abderrahmani, Amar

    2016-01-01

    Elevated plasma concentration of the pro-atherogenic oxidized low density lipoprotein cholesterol (LDL) triggers adverse effects in pancreatic beta-cells and is associated with type 2 diabetes. Here, we investigated whether the endoplasmic reticulum (ER) stress is a key player coupling oxidative stress to beta-cell dysfunction and death elicited by human oxidized LDL. We found that human oxidized LDL activates ER stress as evidenced by the activation of the inositol requiring 1α, and the elevated expression of both DDIT3 (also called CHOP) and DNAJC3 (also called P58IPK) ER stress markers in isolated human islets and the mouse insulin secreting MIN6 cells. Silencing of Chop and inhibition of ER stress markers by the chemical chaperone phenyl butyric acid (PBA) prevented cell death caused by oxidized LDL. Finally, we found that oxidative stress accounts for activation of ER stress markers induced by oxidized LDL. Induction of Chop/CHOP and p58IPK/P58IPK by oxidized LDL was mimicked by hydrogen peroxide and was blocked by co-treatment with the N-acetylcystein antioxidant. As a conclusion, the harmful effects of oxidized LDL in beta-cells requires ER stress activation in a manner that involves oxidative stress. This mechanism may account for impaired beta-cell function in diabetes and can be reversed by antioxidant treatment. PMID:27636901

  18. The toll-like receptor signaling molecule Myd88 contributes to pancreatic beta-cell homeostasis in response to injury.

    PubMed

    Bollyky, Paul L; Bice, Jeffrey B; Sweet, Ian R; Falk, Ben A; Gebe, John A; Clark, April E; Gersuk, Vivian H; Aderem, Alan; Hawn, Thomas R; Nepom, Gerald T

    2009-01-01

    Commensal flora and pathogenic microbes influence the incidence of diabetes in animal models yet little is known about the mechanistic basis of these interactions. We hypothesized that Myd88, an adaptor molecule in the Toll-like-receptor (TLR) pathway, regulates pancreatic beta-cell function and homeostasis. We first examined beta-cells histologically and found that Myd88-/- mice have smaller islets in comparison to C57Bl/6 controls. Myd88-/- mice were nonetheless normoglycemic both at rest and after an intra-peritoneal glucose tolerance test (IPGTT). In contrast, after low-dose streptozotocin (STZ) challenge, Myd88-/-mice had an abnormal IPGTT relative to WT controls. Furthermore, Myd88-/- mice suffer enhanced beta-cell apoptosis and have enhanced hepatic damage with delayed recovery upon low-dose STZ treatment. Finally, we treated WT mice with broad-spectrum oral antibiotics to deplete their commensal flora. In WT mice, low dose oral lipopolysaccharide, but not lipotichoic acid or antibiotics alone, strongly promoted enhanced glycemic control. These data suggest that Myd88 signaling and certain TLR ligands mediate a homeostatic effect on beta-cells primarily in the setting of injury.

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

    PubMed

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

    2013-01-01

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

  20. A survival Kit for pancreatic beta cells: stem cell factor and c-Kit receptor tyrosine kinase.

    PubMed

    Feng, Zhi-Chao; Riopel, Matthew; Popell, Alex; Wang, Rennian

    2015-04-01

    The interactions between c-Kit and its ligand, stem cell factor (SCF), play an important role in haematopoiesis, pigmentation and gametogenesis. c-Kit is also found in the pancreas, and recent studies have revealed that c-Kit marks a subpopulation of highly proliferative pancreatic endocrine cells that may harbour islet precursors. c-Kit governs and maintains pancreatic endocrine cell maturation and function via multiple signalling pathways. In this review we address the importance of c-Kit signalling within the pancreas, including its profound role in islet morphogenesis, islet vascularisation, and beta cell survival and function. We also discuss the impact of c-Kit signalling in pancreatic disease and the use of c-Kit as a potential target for the development of cell-based and novel drug therapies in the treatment of diabetes.

  1. Pancreatic beta-cell-specific targeted disruption of glucokinase gene. Diabetes mellitus due to defective insulin secretion to glucose.

    PubMed

    Terauchi, Y; Sakura, H; Yasuda, K; Iwamoto, K; Takahashi, N; Ito, K; Kasai, H; Suzuki, H; Ueda, O; Kamada, N

    1995-12-22

    Mice carrying a null mutation in the glucokinase (GK) gene in pancreatic beta-cells, but not in the liver, were generated by disrupting the beta-cell-specific exon. Heterozygous mutant mice showed early-onset mild diabetes due to impaired insulin-secretory response to glucose. Homozygotes showed severe diabetes shortly after birth and died within a week. GK-deficient islets isolated from homozygotes showed defective insulin secretion in response to glucose, while they responded to other secretagogues: almost normally to arginine and to some extent to sulfonylureas. These data provide the first direct proof that GK serves as a glucose sensor molecule for insulin secretion and plays a pivotal role in glucose homeostasis. GK-deficient mice serve as an animal model of the insulin-secretory defect in human non-insulin-dependent diabetes mellitus.

  2. Derepression of Polycomb targets during pancreatic organogenesis allows insulin-producing beta-cells to adopt a neural gene activity program

    PubMed Central

    van Arensbergen, Joris; García-Hurtado, Javier; Moran, Ignasi; Maestro, Miguel Angel; Xu, Xiaobo; Van de Casteele, Mark; Skoudy, Anouchka L.; Palassini, Matteo; Heimberg, Harry; Ferrer, Jorge

    2010-01-01

    The epigenome changes that underlie cellular differentiation in developing organisms are poorly understood. To gain insights into how pancreatic beta-cells are programmed, we profiled key histone methylations and transcripts in embryonic stem cells, multipotent progenitors of the nascent embryonic pancreas, purified beta-cells, and 10 differentiated tissues. We report that despite their endodermal origin, beta-cells show a transcriptional and active chromatin signature that is most similar to ectoderm-derived neural tissues. In contrast, the beta-cell signature of trimethylated H3K27, a mark of Polycomb-mediated repression, clusters with pancreatic progenitors, acinar cells and liver, consistent with the epigenetic transmission of this mark from endoderm progenitors to their differentiated cellular progeny. We also identified two H3K27 methylation events that arise in the beta-cell lineage after the pancreatic progenitor stage. One is a wave of cell-selective de novo H3K27 trimethylation in non-CpG island genes. Another is the loss of bivalent and H3K27me3-repressed chromatin in a core program of neural developmental regulators that enables a convergence of the gene activity state of beta-cells with that of neural cells. These findings reveal a dynamic regulation of Polycomb repression programs that shape the identity of differentiated beta-cells. PMID:20395405

  3. PED/PEA-15 regulates glucose-induced insulin secretion by restraining potassium channel expression in pancreatic beta-cells.

    PubMed

    Miele, Claudia; Raciti, Gregory Alexander; Cassese, Angela; Romano, Chiara; Giacco, Ferdinando; Oriente, Francesco; Paturzo, Flora; Andreozzi, Francesco; Zabatta, Assunta; Troncone, Giancarlo; Bosch, Fatima; Pujol, Anna; Chneiweiss, Hervé; Formisano, Pietro; Beguinot, Francesco

    2007-03-01

    The phosphoprotein enriched in diabetes/phosphoprotein enriched in astrocytes (ped/pea-15) gene is overexpressed in human diabetes and causes this abnormality in mice. Transgenic mice with beta-cell-specific overexpression of ped/pea-15 (beta-tg) exhibited decreased glucose tolerance but were not insulin resistant. However, they showed impaired insulin response to hyperglycemia. Islets from the beta-tg also exhibited little response to glucose. mRNAs encoding the Sur1 and Kir6.2 potassium channel subunits and their upstream regulator Foxa2 were specifically reduced in these islets. Overexpression of PED/PEA-15 inhibited the induction of the atypical protein kinase C (PKC)-zeta by glucose in mouse islets and in beta-cells of the MIN-6 and INS-1 lines. Rescue of PKC-zeta activity elicited recovery of the expression of the Sur1, Kir6.2, and Foxa2 genes and of glucose-induced insulin secretion in PED/PEA-15-overexpressing beta-cells. Islets from ped/pea-15-null mice exhibited a twofold increased activation of PKC-zeta by glucose; increased abundance of the Sur1, Kir6.2, and Foxa2 mRNAs; and enhanced glucose effect on insulin secretion. In conclusion, PED/PEA-15 is an endogenous regulator of glucose-induced insulin secretion, which restrains potassium channel expression in pancreatic beta-cells. Overexpression of PED/PEA-15 dysregulates beta-cell function and is sufficient to impair glucose tolerance in mice.

  4. Important role of phosphodiesterase 3B for the stimulatory action of cAMP on pancreatic beta-cell exocytosis and release of insulin.

    PubMed

    Härndahl, Linda; Jing, Xing-Jun; Ivarsson, Rosita; Degerman, Eva; Ahrén, Bo; Manganiello, Vincent C; Renström, Erik; Holst, Lena Stenson

    2002-10-04

    Cyclic AMP potentiates glucose-stimulated insulin release and mediates the stimulatory effects of hormones such as glucagon-like peptide 1 (GLP-1) on pancreatic beta-cells. By inhibition of cAMP-degrading phosphodiesterase (PDE) and, in particular, selective inhibition of PDE3 activity, stimulatory effects on insulin secretion have been observed. Molecular and functional information on beta-cell PDE3 is, however, scarce. To provide such information, we have studied the specific effects of the PDE3B isoform by adenovirus-mediated overexpression. In rat islets and rat insulinoma cells, approximate 10-fold overexpression of PDE3B was accompanied by a 6-8-fold increase in membrane-associated PDE3B activity. The cAMP concentration was significantly lowered in transduced cells (INS-1(832/13)), and insulin secretion in response to stimulation with high glucose (11.1 mm) was reduced by 40% (islets) and 50% (INS-1). Further, the ability of GLP-1 (100 nm) to augment glucose-stimulated insulin secretion was inhibited by approximately 30% (islets) and 70% (INS-1). Accordingly, when stimulating with cAMP, a substantial decrease (65%) in exocytotic capacity was demonstrated in patch-clamped single beta-cells. In untransduced insulinoma cells, application of the PDE3-selective inhibitor OPC3911 (10 microm) was shown to increase glucose-stimulated insulin release as well as cAMP-enhanced exocytosis. The findings suggest a significant role of PDE3B as an important regulator of insulin secretory processes.

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

    PubMed

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

    2004-04-01

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

  6. GLUT-2 function in glucose-unresponsive beta cells of dexamethasone-induced diabetes in rats.

    PubMed Central

    Ohneda, M; Johnson, J H; Inman, L R; Unger, R H

    1993-01-01

    Spontaneous and dexamethasone-induced noninsulin-dependent diabetes mellitus (NIDDM) in rats is associated with loss of glucose-stimulated insulin secretion (GSIS) and a reduction in both GLUT-2-positive beta cells and high Km glucose transport. To determine if the chronology and correlation of these abnormalities is consistent with a causal relationship, Zucker (fa/fa) rats were studied longitudinally before and during 10 d of dexamethasone-induced (0.4 mg/kg per d i.p.) NIDDM. Within 24 h of dexamethasone treatment blood glucose rose and GSIS declined, becoming paradoxically negative (-87 +/- 12 microU/ml per min) on day 10. Blood glucose was negatively correlated with GSIS (r = -0.92; P < 0.001). 3-0-methyl-D-glucose (3MG) transport was unchanged at 12 h, 23% below normal on day 1, and declined further to a nadir 59% below normal. The GLUT-2-positive beta cell area did not decline until 48 h, reaching a nadir of 35% of normal at 10 d. The area of GLUT-2-positive beta cells was correlated with GSIS (r = 0.77; P < 0.005). We conclude that the chronology and correlation between GSIS loss and hyperglycemia is consistent with a cause-effect relationship, but that the subtotal impairment in glucose transport by itself cannot explain the total loss of GSIS if one assumes that normal beta cells are functionally homogenous. Images PMID:8408647

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

    SciTech Connect

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

    2010-03-15

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

  8. In Type 1 Diabetes a Subset of Anti-Coxsackievirus B4 Antibodies Recognize Autoantigens and Induce Apoptosis of Pancreatic Beta Cells

    PubMed Central

    Dolcino, Marzia; Giannattasio, Alessandro; d’Annunzio, Giuseppe; Rigo, Antonella; Pedemonte, Nicoletta; Corrocher, Roberto; Puccetti, Antonio

    2013-01-01

    Type 1 diabetes is characterized by autoimmune destruction of pancreatic beta cells. The role played by autoantibodies directed against beta cells antigens in the pathogenesis of the disease is still unclear. Coxsackievirus B infection has been linked to the onset of type 1 diabetes; however its precise role has not been elucidated yet. To clarify these issues, we screened a random peptide library with sera obtained from 58 patients with recent onset type 1 diabetes, before insulin therapy. We identified an immunodominant peptide recognized by the majority of individual patients’sera, that shares homology with Coxsackievirus B4 VP1 protein and with beta-cell specific autoantigens such as phogrin, phosphofructokinase and voltage-gated L-type calcium channels known to regulate beta cell apoptosis. Antibodies against the peptide affinity-purified from patients’ sera, recognized the viral protein and autoantigens; moreover, such antibodies induced apoptosis of the beta cells upon binding the L-type calcium channels expressed on the beta cell surface, suggesting a calcium dependent mechanism. Our results provide evidence that in autoimmune diabetes a subset of anti-Coxsackievirus antibodies are able to induce apoptosis of pancreatic beta cells which is considered the most critical and final step in the development of autoimmune diabetes without which clinical manifestations do not occur. PMID:23469060

  9. Inflammatory stress of pancreatic beta cells drives release of extracellular heat shock protein 90α.

    PubMed

    Ocaña, Gail J; Pérez, Liliana; Guindon, Lynette; Deffit, Sarah N; Evans-Molina, Carmella; Thurmond, Debbie C; Blum, Janice S

    2017-02-11

    A major obstacle in predicting and preventing the development of autoimmune type 1 diabetes (T1D) in at-risk individuals is the lack of well-established early biomarkers indicative of ongoing beta cell stress during the pre-clinical phase of disease. Recently, serum levels of the alpha cytoplasmic isoform of heat shock protein (HSP) 90 were shown to be elevated in individuals with new-onset T1D. We therefore hypothesized HSP90α could be released from beta cells in response to cellular stress and inflammation associated with the earliest stages of T1D. Here, human beta cell lines and cadaveric islets released HSP90α in response to stress induced by treatment with a combination of pro-inflammatory cytokines including IL-1β, TNF-α, and IFN-γ. Mechanistically, HSP90α release was found to be driven by cytokine-induced endoplasmic reticulum (ER) stress mediated by c-Jun N-terminal kinase (JNK), a pathway that can eventually lead to beta cell apoptosis. Cytokine-induced beta cell HSP90α release and JNK activation were significantly reduced by pre-treating cells with the ER stress-mitigating chemical chaperone tauroursodeoxycholic acid (TUDCA). HSP90α release by cells may thus be a sensitive indicator of stress during inflammation and a useful tool in assessing therapeutic mitigation of cytokine-induced cell damage linked to autoimmunity. This article is protected by copyright. All rights reserved.

  10. Osteopontin Affects Insulin Vesicle Localization and Ca2+ Homeostasis in Pancreatic Beta Cells from Female Mice

    PubMed Central

    Mollet, Inês G.; Knutsson, Anki; Bolmgren, Victor S.; Hultgårdh-Nilsson, Anna; Gomez, Maria F.; Eliasson, Lena

    2017-01-01

    Type 2 diabetic patients suffer from insulin resistance and reduced insulin secretion. Osteopontin (OPN), a versatile protein expressed in several tissues throughout the body including the islets of Langerhans, has previously been implicated in the development of insulin resistance. Here we have investigated the role of OPN in insulin secretion using an OPN knock out mouse model (OPN-/-). Ultra-structural analyzes of islets from OPN-/- and WT mice indicated weaker cell-cell connections between the islet cells in the OPN-/- mouse compared to WT. Analysis of the insulin granule distribution in the beta cells showed that although OPN-/- and WT beta cells have the same number of insulin granules OPN-/- beta cells have significantly fewer docked granules. Both OPN-/- and WT islets displayed synchronized Ca2+ oscillations indicative of an intact beta cell communication. OPN-/- islets displayed higher intracellular Ca2+ concentrations when stimulated with 16.7 mM glucose than WT islets and the initial dip upon elevated glucose concentrations (which is associated with Ca2+ uptake into ER) was significantly lower in these islets. Glucose-induced insulin secretion was similar in OPN-/- and WT islets. Likewise, non-fasted blood glucose levels were the same in both groups. In summary, deletion of OPN results in several minor beta-cell defects that can be compensated for in a healthy system. PMID:28107503

  11. Coupling of Insulin Secretion and Display of a Granule-resident Zinc Transporter ZnT8 on the Surface of Pancreatic Beta Cells.

    PubMed

    Huang, Qiong; Merriman, Chengfeng; Zhang, Hao; Fu, Dax

    2017-03-10

    The islet-specific zinc transporter ZnT8 mediates zinc enrichment in the insulin secretory granules of the pancreatic beta cell. This granular zinc transporter is also a major self-antigen found in type 1 diabetes patients. It is not clear whether ZnT8 can be displayed on the cell surface and how insulin secretion may regulate the level of ZnT8 exposure to extracellular immune surveillance. Here we report specific antibody binding to the extracellular surface of rat insulinoma INS-1E cells that stably expressed a tagged human zinc transporter ZnT8. Flow cytometry analysis after fluorescent antibody labeling revealed strong correlations among the levels of ZnT8 expression, its display on the cell surface, and glucose-stimulated insulin secretion (GSIS). Glucose stimulation increased the surface display of endogenous ZnT8 from a basal level to 32.5% of the housekeeping Na(+)/K(+) ATPase on the cell surface, thereby providing direct evidence for a GSIS-dependent surface exposure of the ZnT8 self-antigen. Moreover, the variation in tagged-ZnT8 expression and surface labeling enabled sorting of heterogeneous beta cells to subpopulations that exhibited marked differences in GSIS with parallel changes in endogenous ZnT8 expression. The abundant surface display of endogenous ZnT8 and its coupling to GSIS demonstrated the potential of ZnT8 as a surface biomarker for tracking and isolating functional beta cells in mixed cell populations.

  12. A Presenilin/Notch1 pathway regulated by miR-375, miR-30a, and miR-34a mediates glucotoxicity induced-pancreatic beta cell apoptosis

    PubMed Central

    Li, Yating; Zhang, Tao; Zhou, Yuncai; Sun, Yi; Cao, Yue; Chang, Xiaoai; Zhu, Yunxia; Han, Xiao

    2016-01-01

    The presenilin-mediated Notch1 cleavage pathway plays a critical role in controlling pancreatic beta cell fate and survival. The aim of the present study was to investigate the role of Notch1 activation in glucotoxicity-induced beta cell impairment and the contributions of miR-375, miR-30a, and miR-34a to this pathway. We found that the protein levels of presenilins (PSEN1 and PSEN2), and NOTCH1 were decreased in INS-1 cells after treatment with increased concentrations of glucose, whereas no significant alteration of mRNA level of Notch1 was observed. Targeting of miR-375, miR-30a, and miR-34a to the 3′utr of Psen1, Psen2, and Notch1, respectively, reduced the amounts of relevant proteins, thereby reducing NICD1 amounts and causing beta cell apoptosis. Overexpression of NICD1 blocked the effects of glucotoxicity as well as miRNA overabundance. Downregulating the expression of miR-375, miR-30a, and miR-34a restored PSEN1, PSEN2, and NICD1 production and prevented glucotoxicity-induced impairment of the beta cells. These patterns of miRNA regulation of the Notch1 cleavage pathway were reproduced in GK rats as well as in aged rats. Our findings demonstrated that miRNA-mediated suppression of NICD1 links the presenilin/Notch1 pathway to glucotoxicity in mature pancreatic beta cells. PMID:27804997

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

    SciTech Connect

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

    2005-07-01

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

  14. Chronic exposure to free fatty acid reduces pancreatic beta cell insulin content by increasing basal insulin secretion that is not compensated for by a corresponding increase in proinsulin biosynthesis translation.

    PubMed Central

    Bollheimer, L C; Skelly, R H; Chester, M W; McGarry, J D; Rhodes, C J

    1998-01-01

    The pancreatic beta cell normally maintains a stable balance among insulin secretion, insulin production, and insulin degradation to keep optimal intracellular stores of the hormone. Elevated levels of FFA markedly enhance insulin secretion; however, the effects of FFA on insulin production and intracellular stores remain unclear. In this study, twofold elevation in total circulating FFA effected by infusion of lard oil and heparin into rats for 6 h under normoglycemic conditions resulted in a marked elevation of circulating insulin levels evident after 4 h, and a 30% decrease in pancreatic insulin content after a 6-h infusion in vivo. Adding 125 muM oleate to isolated rat pancreatic islets cultured with 5.6 mM glucose caused a 50% fall in their insulin content over 24 h, coupled with a marked enhancement of basal insulin secretion. Both effects of fatty acid were blocked by somatostatin. In contrast to the stimulatory effects of oleate on insulin secretion, glucose-induced proinsulin biosynthesis was inhibited by oleate up to 24 h, but was unaffected thereafter. This result was in spite of a two- to threefold oleate-induced increase in preproinsulin mRNA levels, underscoring the importance of translational regulation of proinsulin biosynthesis in maintaining beta cell insulin stores. Collectively, these results suggest that chronically elevated FFA contribute to beta cell dysfunction in the pathogenesis of NIDDM by significantly increasing the basal rate of insulin secretion. This increase in turn results in a decrease in the beta cell's intracellular stores that cannot be offset by commensurate FFA induction of proinsulin biosynthesis. PMID:9486980

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

    SciTech Connect

    Yamabe, Noriko; Kang, Ki Sung; Zhu Baoting

    2010-11-15

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

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

    PubMed Central

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2011-01-14

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

  19. LGR5 and Nanog identify stem cell signature of pancreas beta cells which initiate pancreatic cancer.

    PubMed

    Amsterdam, Abraham; Raanan, Calanit; Schreiber, Letizia; Polin, Nava; Givol, David

    2013-04-05

    Pancreas cancer, is the fourth leading cause of cancer death but its cell of origin is controversial. We compared the localization of stem cells in normal and cancerous pancreas using antibodies to the stem cell markers Nanog and LGR5. Here we show, for the first time, that LGR5 is expressed in normal pancreas, exclusively in the islets of Langerhans and it is co-localized, surprisingly, with Nanog and insulin in clusters of beta cells. In cancerous pancreas Nanog and LGR5 are expressed in the remaining islets and in all ductal cancer cells. We observed insulin staining among the ductal cancer cells, but not in metastases. This indicates that the islet's beta cells, expressing LGR5 and Nanog markers are the initiating cells of pancreas cancer, which migrated from the islets to form the ductal cancerous tissue, probably after mutation and de-differentiation. This discovery may facilitate treatment of this devastating cancer.

  20. Cytokines downregulate the sarcoendoplasmic reticulum pump Ca2+ ATPase 2b and deplete endoplasmic reticulum Ca2+, leading to induction of endoplasmic reticulum stress in pancreatic beta-cells.

    PubMed

    Cardozo, Alessandra K; Ortis, Fernanda; Storling, Joachim; Feng, Ying-Mei; Rasschaert, Joanne; Tonnesen, Morten; Van Eylen, Françoise; Mandrup-Poulsen, Thomas; Herchuelz, André; Eizirik, Décio L

    2005-02-01

    Cytokines and free radicals are mediators of beta-cell death in type 1 diabetes. Under in vitro conditions, interleukin-1beta (IL-1beta) + gamma-interferon (IFN-gamma) induce nitric oxide (NO) production and apoptosis in rodent and human pancreatic beta-cells. We have previously shown, by microarray analysis of primary beta-cells, that IL-1beta + IFN-gamma decrease expression of the mRNA encoding for the sarcoendoplasmic reticulum pump Ca(2+) ATPase 2b (SERCA2b) while inducing expression of the endoplasmic reticulum stress-related and proapoptotic gene CHOP (C/EBP [CCAAT/enhancer binding protein] homologous protein). In the present study we show that cytokine-induced apoptosis and necrosis in primary rat beta-cells and INS-1E cells largely depends on NO production. IL-1beta + IFN-gamma, via NO synthesis, markedly decreased SERCA2b protein expression and depleted ER Ca(2+) stores. Of note, beta-cells showed marked sensitivity to apoptosis induced by SERCA blockers, as compared with fibroblasts. Cytokine-induced ER Ca(2+) depletion was paralleled by an NO-dependent induction of CHOP protein and activation of diverse components of the ER stress response, including activation of inositol-requiring ER-to-nucleus signal kinase 1alpha (IRE1alpha) and PRK (RNA-dependent protein kinase)-like ER kinase (PERK)/activating transcription factor 4 (ATF4), but not ATF6. In contrast, the ER stress-inducing agent thapsigargin triggered these four pathways in parallel. In conclusion, our results suggest that the IL-1beta + IFN-gamma-induced decrease in SERCA2b expression, with subsequent depletion of ER Ca(2+) and activation of the ER stress pathway, is a potential contributory mechanism to beta-cell death.

  1. Tiam1/Rac1 signaling pathway mediates palmitate-induced, ceramide-sensitive generation of superoxides and lipid peroxides and the loss of mitochondrial membrane potential in pancreatic beta-cells.

    PubMed

    Syed, Ismail; Jayaram, Bhavaani; Subasinghe, Wasanthi; Kowluru, Anjaneyulu

    2010-09-15

    The phagocytic NADPH oxidase [NOX] has been implicated in the generation of superoxides in the pancreatic beta-cell. Herein, using normal rat islets and clonal INS 832/13 cells, we tested the hypothesis that activation of the small G-protein Rac1, which is a member of the NOX holoenzyme, is necessary for palmitate [PA]-induced generation of superoxides in pancreatic beta-cells. Incubation of isolated beta-cells with PA potently increased the NOX activity culminating in a significant increase in the generation of superoxides and lipid peroxides in these cells; such effects of PA were attenuated by diphenyleneiodonium [DPI], a known inhibitor of NOX. In addition, PA caused a transient, but significant activation [i.e., GTP-bound form] of Rac1 in these cells. NSC23766, a selective inhibitor of Rac1, but not Cdc42 or Rho activation, inhibited Rac1 activation and the generation of superoxides and lipid peroxides induced by PA. Fumonisin B-1 [FB-1], which inhibits de novo synthesis of ceramide [CER] from PA, also attenuated PA-induced superoxide and lipid peroxide generation and NOX activity implicating intracellularly generated CER in the metabolic effects of PA; such effects were also demonstrable in the presence of the cell-permeable C2-CER. Further, NSC23766 prevented C2-CER-induced Rac1 activation and production of superoxides and lipid peroxides. Lastly, C2-CER, but not its inactive analogue, significantly reduced the mitochondrial membrane potential, which was prevented to a large degree by NSC23766. Together, our findings suggest that Tiam1/Rac1 signaling pathway regulates PA-induced, CER-dependent superoxide generation and mitochondrial dysfunction in pancreatic beta-cells.

  2. Insulin receptor isoform A confers a higher proliferative capability to pancreatic beta cells enabling glucose availability and IGF-I signaling.

    PubMed

    Escribano, Oscar; Gómez-Hernández, Almudena; Díaz-Castroverde, Sabela; Nevado, Carmen; García, Gema; Otero, Yolanda F; Perdomo, Liliana; Beneit, Nuria; Benito, Manuel

    2015-07-05

    The main compensatory response to insulin resistance is the pancreatic beta cell hyperplasia to account for increased insulin secretion. In fact, in a previous work we proposed a liver-pancreas endocrine axis with IGF-I (insulin-like growth factor type I) secreted by the liver acting on IRA insulin receptor in beta cells from iLIRKO mice (inducible Liver Insulin Receptor KnockOut) that showed a high IRA/IRB ratio. However, the role of insulin receptor isoforms in the IGF-I-induced beta cell proliferation as well as the underlying molecular mechanisms remain poorly understood. For this purpose, we have used four immortalized mouse beta cell lines: bearing IR (IRLoxP), lacking IR (IRKO), expressing exclusively IRA (IRA), or alternatively expressing IRB (IRB). Pancreatic beta cell proliferation studies showed that IRA cells are more sensitive than those expressing IRB to the mitogenic response induced by IGF-I, acting through the pathway IRA/IRS-1/2/αp85/Akt/mTORC1/p70S6K. More importantly, IRA beta cells, but not IRB, showed an increased glucose uptake as compared with IRLoxP cells, this effect being likely owing to an enhanced association between Glut-1 and Glut-2 with IRA. Overall, our results strongly suggest a prevalent role of IRA in glucose availability and IGF-I-induced beta cell proliferation mainly through mTORC1. These results could explain, at least partially, the role played by the liver-secreted IGF-I in the compensatory beta cell hyperplasia observed in response to severe hepatic insulin resistance in iLIRKO mice.

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

    PubMed Central

    Fridlyand, Leonid E.; Philipson, Louis H.

    2016-01-01

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

  4. Temporal sequence of metabolic and ionic events in glucose-stimulated clonal pancreatic beta-cells (HIT).

    PubMed

    Civelek, V N; Deeney, J T; Kubik, K; Schultz, V; Tornheim, K; Corkey, B E

    1996-05-01

    Stimulation of insulin release by glucose requires increased metabolism of glucose and a rise in cytosolic free Ca2+ in the pancreatic beta-cell. It is accompanied by increases in respiratory rate, pyridine and flavin nucleotide reduction state, intracellular pH and the ATP/ADP ratio. To test alternative proposals of the regulatory relationships among free Ca2+, mitochondrial metabolism and cellular energy state, we determined the temporal sequence of these metabolic and ionic changes following addition of glucose to clonal pancreatic beta-cells (HIT). Combined measurements of the native fluorescence of reduced pyridine nucleotides and oxidized flavin, intracellular pH, and free Ca2+ were performed together with simultaneous measurement of O2 tension or removal of samples for assay of the ATP/ADP ratio. The initial changes were detected in three phases. First, decreases occurred in the ATP/ADP ratio (<3 s) and increases in pyridine (2 +/- 1 s) and flavin (2 +/- 1 s) nucleotide reduction. Next, increases in the O2 consumption rate (20 +/- 5 s), the ATP/ADP ratio (29 +/- 12 s) and internal pH (48 +/- 5 s) were observed. Finally, cytosolic free Ca2+ rose (114 +/- 10 s). Maximal changes in the ATP/ADP ratio, O2 consumption and pyridine and flavin nucleotide fluorescence preceded the beginning of the Ca2+ change. These relationships are consistent with a model in which phosphorylation of glucose is the initial event which generates the signals that lead to an increase in respiration, a rise in the ATP/ADP ratio and finally influx of Ca2+. Our results indicate that Ca2+ does not function as the initiator of increased mitochondrial respiration.

  5. Membrane anchoring of the autoantigen GAD65 to microvesicles in pancreatic beta-cells by palmitoylation in the NH2-terminal domain

    PubMed Central

    1992-01-01

    Pancreatic beta-cells and gamma-aminobutyric acid (GABA)-secreting neurons both express the enzyme glutamic acid decarboxylase (GAD) which is a major target of autoantibodies associated with beta-cell destruction and impairment of GABA-ergic neurotransmitter pathways. The predominant form of GAD in pancreatic beta-cells, GAD65, is synthesized as a soluble hydrophilic molecule, which is modified to become firmly membrane anchored. Here we show by immunogold electron microscopy that GAD65 is localized to the membrane of small vesicles which are identical in size to small synaptic-like microvesicles in pancreatic beta-cells. The NH2-terminal domain of GAD65 is the site of a two-step modification, the last of which results in a firm membrane anchoring that involves posttranslational hydroxylamine sensitive palmitoylation. GAD65 can be released from the membrane by an apparent enzyme activity in islets, suggesting that the membrane anchoring step is reversible and potentially regulated. The hydrophobic modifications and consequent membrane anchoring of GAD65 to microvesicles that store its product GABA may be of functional importance and, moreover, significant for its selective role as an autoantigen. PMID:1321158

  6. Importin beta1 mediates the glucose-stimulated nuclear import of pancreatic and duodenal homeobox-1 in pancreatic islet beta-cells (MIN6).

    PubMed Central

    Guillemain, Ghislaine; Da Silva Xavier, Gabriela; Rafiq, Imran; Leturque, Armelle; Rutter, Guy A

    2004-01-01

    The transcription factor PDX-1 (pancreatic and duodenal homeobox-1) is essential for pancreatic development and the maintainence of expression of islet beta-cell-specific genes. In an previous study [Rafiq, Kennedy and Rutter (1998) J. Biol. Chem. 273, 23241-23247] we demonstrated that PDX-1 may be activated at elevated glucose concentrations by translocation from undefined binding sites in the cytosol and nuclear membrane into the nucleoplasm. In the present study, we show that PDX-1 interacts directly and specifically in vitro with the nuclear import receptor family member, importin beta1, and that this interaction is mediated by the PDX-1 homeodomain (amino acids 146-206). Demonstrating the functional importance of the PDX-1-importin beta1 interaction, microinjection of MIN6 beta-cells with anti-(importin beta1) antibodies blocked both the nuclear translocation of PDX-1, and the activation by glucose (30 mM versus 3 mM) of the pre-proinsulin promoter. However, treatment with extracts from pancreatic islets incubated at either low or high glucose concentrations had no impact on the ability of PDX-1 to interact with importin beta1 in vitro. Furthermore, importin beta1 also interacted with SREBP1c (sterol-regulatory-element-binding protein 1c) in vitro, and microinjection of importin beta1 antibodies blocked the activation by glucose of SREBP1c target genes. Since the subcellular distribution of SREBP1c is unaffected by glucose, these findings suggest that a redistribution of importin beta1 is unlikely to explain the glucose-stimulated nuclear uptake of PDX-1. Instead, we conclude that the uptake of PDX-1 into the nucleoplasm, as glucose concentrations increase, may be mediated by release of the factor both from sites of retention in the cytosol and from non-productive complexes with importin beta1 at the nuclear membrane. PMID:14632628

  7. Hispidin produced from Phellinus linteus protects pancreatic beta-cells from damage by hydrogen peroxide.

    PubMed

    Jang, Jae Soon; Lee, Jong Seok; Lee, Jung Hyun; Kwon, Duck Soo; Lee, Keun Eok; Lee, Shin Young; Hong, Eock Kee

    2010-06-01

    Phellinus linteus, which is a traditional medicinal mushroom used in Asian countries for the treatment of various diseases, has attracted a lot of attention due to its antioxidant, anti-inflammatory, anti-mutagenicity, and cell-mediated immunity properties in addition to its ability to inhibit tumor growth and metastasis. However, the antidiabetic efficacy of P. linteus has not yet been examined. In this study, hispidin from P. linteus exhibited quenching effects against DPPH radicals, superoxide radicals, and hydrogen peroxide in a dose-dependent manner. Intracellular reactive oxygen species scavenging activity of hispidin was approximately 55% at a concentration of 30 microM. In addition, hispidin was shown to inhibit hydrogen peroxide-induced apoptosis and increased insulin secretion in hydrogen peroxide-treated cells. These combined results indicate that hispidin may act as an antidiabetic and that this property occurs through preventing beta-cells from the toxic action of reactive oxygen species in diabetes.

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

    PubMed

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

    2016-08-01

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

  9. The intrinsic rhythmicity of spike-burst generation in pancreatic beta-cells and intercellular interaction within an islet.

    PubMed

    Kitasato, H; Kai, R; Ding, W G; Omatsu-Kanbe, M

    1996-10-01

    The pancreatic beta-cell has four types of Ca2+ channel (L-type, T-type, low-threshold slowly inactivating, and low-threshold non-inactivating Ca2+), although the low-threshold non-inactivating Ca2+ channel has not yet been confirmed experimentally. Beside these, there are at least three types of K+ channels (K(ATP), K(Ca,V), and K(V)), and transporters (GLUT-2, Na+/Ca(2+)-countertransporter, and Na+/K(+)-pump) as schematically shown in Fig.4. Opinions on the mechanism of spike-burst are converging to the following view: At intermediate glucose concentrations, the intracellular ATP/ADP ratio oscillates in the following way. A gradual rise in the ATP/ADP ratio causes gradual progression of depolarization to the threshold for the low-threshold Ca2+ channels, of which the opening causes regenerative depolarization to the plateau potential on which spikes (the L-type Ca2+ channel contributes to spike firing) are superimposed. During the active phase, a fall in the ATP/ADP ratio follows a gradual rise in ATP consumption. Slight repolarization due to the opening of a small fraction of K(ATP) channels triggers regenerative repolarization. With the progress of repolarization, a residual fraction of voltage-gated Ca2+ channels (low-threshold non-inactivating) are deactivated. During the silent phase, a gradual rise in the ATP/ ADP ratio leads to gradual depolarization back to the threshold for the next spike-burst. There are still a diversity of views regarding the mechanism of the initial spike-train. On the basis of observations made in various laboratories including ours, we propose the following working model: At low concentrations of glucose, alpha-cells secret glucagon which induces a rise in cAMP in beta-cells lodged in the same islet. A rise in cAMP itself does not activate the enzymes relevant to glycogenolysis, but merely prepares to activate the enzymes. When extracellular glucose increases, Ca2+ spikes are elicited. Influxed Ca2+ ions, together with cAMP, work

  10. The protective activity of Urtica dioica leaves on blood glucose concentration and beta-cells in streptozotocin-diabetic rats.

    PubMed

    Golalipour, Mohammad Jafar; Khori, Vahid

    2007-04-15

    This study was done to determine the protective activity of the hydroalcholic extract of Urtica dioica leaves on Hyperglycemia and beta-cells in hyperglycemic rats. Thirty Wistar rats were allocated in groups of normal, Diabetic and treatment. Hyperglycemia in Rats induced by 80 mg kg(-1) streptozotocin. In treatment group, animals received hydroalcholic extract of Urtica dioica 100 mg kg(-1) day(-1) for five days, intraperitoneally and then hyperglycemia induced by streptozotocin. The blood glucose concentration was measured by using a Glucometer in 1st, 3rd and 5th weeks. In the end of 5th weeks the animals in each group were sacrificed by anesthesia and whole pancreas in three groups extracted and fixed in bouin's fluid and stained by chromealum hematoxiline-phloxine and beta cells were counted in three groups by Olympus microscope. Mean +/- SE of blood glucose concentrations in the end of fifth weeks were 99.4 +/-5.0, 454.7 +/- 34.5 and 303.6 +/- 100.6 in control, diabetic and treatment groups, respectively (p < 0.05). The percentages of beta-cells in control, diabetic and treatment groups were 73.6, 1.9 and 22.9%, respectively. The percentage of beta-cells in treatment group comparing with diabetic group was significant (p < 0.05). This study showed that the protective administration of hydroalcholic extract of Urtica dioica has hypoglycemic effect and protective activity of beta-cells of langerhans in hyperglycemic rats.

  11. Effects of intracellular pH on ATP-sensitive K+ channels in mouse pancreatic beta-cells.

    PubMed Central

    Proks, P; Takano, M; Ashcroft, F M

    1994-01-01

    1. The effects of intracellular pH (pHi) on the ATP-sensitive K+ channel (K+ATP channel) from mouse pancreatic beta-cells were examined in inside-out patches exposed to symmetrical 140 mM K+ solutions. 2. The relationship between channel activity and pHi was described by the Hill equation with half-maximal inhibition (Ki) at pHi 6.25 and a Hill coefficient of 3.7. 3. Following exposure to pHi < 6.8, channel activity did not recover to its original level. Subsequent application of trypsin to the intracellular membrane surface restored channel activity to its initial level or above. 4. At -60 mV the relationship between pHi and the single-channel current amplitude was described by a modified Hill equation with a Hill coefficient of 2.1, half-maximal inhibition at pHi 6.48 and a maximum inhibition of 18.5%. 5. A decrease in pHi reduced the extent of channel inhibition by ATP: Ki was 18 microM at pH 7.2 and 33 microM at pH 6.4. The Hill coefficient was also reduced, being 1.65 at pH 7.2 and 1.17 at pH 6.4. 6. When channel activity was plotted as a function of ATP4- (rather than total ATP) there was no effect of pHi on the relationship. This suggests that ATP4- is the inhibitory ion species and that the effects of reducing pHi are due to the lowered concentration of ATP4-. 7. Changes in external pH had little effect on either single-channel or whole-cell K+ATP currents. 8. The effects of pHi do not support a role for H+ in linking glucose metabolism to K+ATP channel inhibition in pancreatic beta-cells. PMID:8189391

  12. Cathepsin inhibition-induced lysosomal dysfunction enhances pancreatic beta-cell apoptosis in high glucose.

    PubMed

    Jung, Minjeong; Lee, Jaemeun; Seo, Hye-Young; Lim, Ji Sun; Kim, Eun-Kyoung

    2015-01-01

    Autophagy is a lysosomal degradative pathway that plays an important role in maintaining cellular homeostasis. We previously showed that the inhibition of autophagy causes pancreatic β-cell apoptosis, suggesting that autophagy is a protective mechanism for the survival of pancreatic β-cells. The current study demonstrates that treatment with inhibitors and knockdown of the lysosomal cysteine proteases such as cathepsins B and L impair autophagy, enhancing the caspase-dependent apoptosis of INS-1 cells and islets upon exposure to high concentration of glucose. Interestingly, treatment with cathepsin B and L inhibitors prevented the proteolytic processing of cathepsins B, D and L, as evidenced by gradual accumulation of the respective pro-forms. Of note, inhibition of aspartic cathepsins had no effect on autophagy and cell viability, suggesting the selective role of cathepsins B and L in the regulation of β-cell autophagy and apoptosis. Lysosomal localization of accumulated pro-cathepsins in the presence of cathepsin B and L inhibitors was verified via immunocytochemistry and lysosomal fractionation. Lysotracker staining indicated that cathepsin B and L inhibitors led to the formation of severely enlarged lysosomes in a time-dependent manner. The abnormal accumulation of pro-cathepsins following treatment with inhibitors of cathepsins B and L suppressed normal lysosomal degradation and the processing of lysosomal enzymes, leading to lysosomal dysfunction. Collectively, our findings suggest that cathepsin defects following the inhibition of cathepsin B and L result in lysosomal dysfunction and consequent cell death in pancreatic β-cells.

  13. Enhanced glucose-induced intracellular signaling promotes insulin hypersecretion: pancreatic beta-cell functional adaptations in a model of genetic obesity and prediabetes.

    PubMed

    Irles, Esperanza; Ñeco, Patricia; Lluesma, Mónica; Villar-Pazos, Sabrina; Santos-Silva, Junia Carolina; Vettorazzi, Jean F; Alonso-Magdalena, Paloma; Carneiro, Everardo M; Boschero, Antonio C; Nadal, Ángel; Quesada, Ivan

    2015-03-15

    Obesity is associated with insulin resistance and is known to be a risk factor for type-2 diabetes. In obese individuals, pancreatic beta-cells try to compensate for the increased insulin demand in order to maintain euglycemia. Most studies have reported that this adaptation is due to morphological changes. However, the involvement of beta-cell functional adaptations in this process needs to be clarified. For this purpose, we evaluated different key steps in the glucose-stimulated insulin secretion (GSIS) in intact islets from female ob/ob obese mice and lean controls. Obese mice showed increased body weight, insulin resistance, hyperinsulinemia, glucose intolerance and fed hyperglycemia. Islets from ob/ob mice exhibited increased glucose-induced mitochondrial activity, reflected by enhanced NAD(P)H production and mitochondrial membrane potential hyperpolarization. Perforated patch-clamp examination of beta-cells within intact islets revealed several alterations in the electrical activity such as increased firing frequency and higher sensitivity to low glucose concentrations. A higher intracellular Ca(2+) mobilization in response to glucose was also found in ob/ob islets. Additionally, they displayed a change in the oscillatory pattern and Ca(2+) signals at low glucose levels. Capacitance experiments in intact islets revealed increased exocytosis in individual ob/ob beta-cells. All these up-regulated processes led to increased GSIS. In contrast, we found a lack of beta-cell Ca(2+) signal coupling, which could be a manifestation of early defects that lead to beta-cell malfunction in the progression to diabetes. These findings indicate that beta-cell functional adaptations are an important process in the compensatory response to obesity.

  14. Virus-induced diabetes mellitus. VI. Genetically determined host differences in the replicating of encephalomyocarditis virus in pancreatic beta cells

    PubMed Central

    1976-01-01

    Beta cells were isolated from strains of mice that were susceptible and resistant to encephalomyocarditis (EMC) viral-induced diabetes mellitus. Beta cells from susceptible mice that were infected in vivo with EMC virus showed higher viral titers, more severe degranulation, and lower concentrations of immunoreactive insulin than beta cells from resistant mice. Immunofluorescence and infectious center assays revealed that pancreas from susceptible mice contained at least 10 times more infected cells than pancreas from resistant mice. Beta cell cultures prepared from susceptible mice and infected in vitro also showed higher viral titers and more severe cytopathologic changes than beta cell cultures from resistant mice. In contrast to beta cell cultures, virus replicated equally well in primary embryo and kidney cell cultures from susceptible and resistant strains of mice. It is concluded that the development of EMC virus-induced diabetes is related to genetically determined host differences in the capacity of the virus to infect beta cells. PMID:177713

  15. Pancreatic beta cells and islets take up thiamin by a regulated carrier-mediated process: studies using mice and human pancreatic preparations

    PubMed Central

    Mee, Lisa; Nabokina, Svetlana M.; Sekar, V. Thillai; Subramanian, Veedamali S.; Maedler, Kathrin; Said, Hamid M.

    2009-01-01

    Thiamin is essential for the normal function of the endocrine pancreas, but very little is known about uptake mechanism(s) and regulation by beta cells. We addressed these issues using mouse-derived pancreatic beta-TC-6 cells, and freshly isolated primary mouse and human pancreatic islets. Results showed that thiamin uptake by beta-TC-6 cells involves a pH (but not Na+)-dependent carrier-mediated process that is saturable at both the nanomolar (apparent Km = 37.17 ± 9.9 nM) and micromolar (apparent Km = 3.26 ± 0.86 μM) ranges, cis-inhibited by thiamin structural analogs, and trans-stimulated by unlabeled thiamin. Involvement of carrier-mediated process was also confirmed in primary mouse and human pancreatic islets. Both THTR-1 and THTR-2 were found to be expressed in these mouse and human pancreatic preparations. Maintaining beta-TC-6 cells in the presence of a high level of thiamin led to a significant (P < 0.01) decrease in thiamin uptake, which was associated with a significant downregulation in level of expression of THTR-1 and THTR-2 at the protein and mRNA levels and a decrease in transcriptional (promoter) activity. Modulators of intracellular Ca2+/calmodulin- and protein-tyrosine kinase-mediated pathways also altered thiamin uptake. Finally, confocal imaging of live beta-TC-6 cells showed that clinical mutants of THTR-1 have mixed expression phenotypes and all led to impairment in thiamin uptake. These studies demonstrate for the first time that thiamin uptake by the endocrine pancreas is carrier mediated and is adaptively regulated by the prevailing vitamin level via transcriptional mechanisms. Furthermore, clinical mutants of THTR-1 impair thiamin uptake via different mechanisms. PMID:19423748

  16. Clonidine promotes the accumulation of /sup 45/Ca in pancreatic beta-cell organelles

    SciTech Connect

    Andersson, T.; Nygren, P.

    1983-12-01

    Glucose-stimulated insulin release from pancreatic islets of ob/ob-mice was inhibited by 10(-9) M of the alpha 2-adrenergic agonist clonidine. This inhibitory effect was abolished by 10(-7) M of the antagonist yohimbine. Loading the islets with /sup 45/Ca during the clonidine exposure followed by isolation of subcellular fractions under conditions known to minimize the /sup 45/Ca redistribution resulted in increased accumulation of the isotope in the mitochondrial and microsomal fractions. It is suggested that clonidine inhibits glucose-stimulated insulin release by increasing the organelle sequestration of Ca2+.

  17. Voltage noise measurements across the pancreatic beta-cell membrane: calcium channel characteristics.

    PubMed Central

    Atwater, I; Dawson, C M; Eddlestone, G T; Rojas, E

    1981-01-01

    1. Membrane potential fluctuations were measured in cells from mouse Islets of Langerhans identified as beta-cells by the characteristic pattern of electrical activity induced by 11 mM-D-glucose. 2. The membrane potential was controlled by adjusting the external potassium concentration, [K+]o, keeping the sum [Na+]o plus [K+]o constant. In the absence of glucose, when [K+]o is raised, the resulting depolarization is accompanied by a significant increase in voltage noise. 3 The amplitude and time course of the voltage noise were measured under various experimental conditions. The variance of the fluctuating voltage decreased monotonically along the depolarization induced by sudden increase in [K+]o, suggesting a monotonic reduction in the number of elementary events. 4. The frequency characteristics of the excess noise could be analysed as the sum of 1/f and 1/f2 components. While the 1/f component remained unaffected by the external application of 20mM-tetraethylammonium (TEA) and either 2 mM-Mn2+ or 2 mM-Co2+, the 1/f2 component was suppressed by both Mn2+ and Co2+. 5. The corner frequency, fc, of the 1/f2 component depended on membrane potential, which was adjusted by adjusting the [K+]o jump. These results support the idea that fc in these experiments is a measure of the channel relaxation. 6. Measurements of the input resistance in the frequency range from 0 to 25 Hz were used to obtain a rough estimate of the size of the channel conductance as 5 x 10(-12) omega (-1). PMID:6273530

  18. Type 1 Diabetes Candidate Genes Linked to Pancreatic Islet Cell Inflammation and Beta-Cell Apoptosis

    PubMed Central

    Størling, Joachim; Pociot, Flemming

    2017-01-01

    Type 1 diabetes (T1D) is a chronic immune-mediated disease resulting from the selective destruction of the insulin-producing pancreatic islet β-cells. Susceptibility to the disease is the result of complex interactions between environmental and genetic risk factors. Genome-wide association studies (GWAS) have identified more than 50 genetic regions that affect the risk of developing T1D. Most of these susceptibility loci, however, harbor several genes, and the causal variant(s) and gene(s) for most of the loci remain to be established. A significant part of the genes located in the T1D susceptibility loci are expressed in human islets and β cells and mounting evidence suggests that some of these genes modulate the β-cell response to the immune system and viral infection and regulate apoptotic β-cell death. Here, we discuss the current status of T1D susceptibility loci and candidate genes with focus on pancreatic islet cell inflammation and β-cell apoptosis. PMID:28212332

  19. A conserved bacterial protein induces pancreatic beta cell expansion during zebrafish development

    PubMed Central

    Hill, Jennifer Hampton; Franzosa, Eric A; Huttenhower, Curtis; Guillemin, Karen

    2016-01-01

    Resident microbes play important roles in the development of the gastrointestinal tract, but their influence on other digestive organs is less well explored. Using the gnotobiotic zebrafish, we discovered that the normal expansion of the pancreatic β cell population during early larval development requires the intestinal microbiota and that specific bacterial members can restore normal β cell numbers. These bacteria share a gene that encodes a previously undescribed protein, named herein BefA (β Cell Expansion Factor A), which is sufficient to induce β cell proliferation in developing zebrafish larvae. Homologs of BefA are present in several human-associated bacterial species, and we show that they have conserved capacity to stimulate β cell proliferation in larval zebrafish. Our findings highlight a role for the microbiota in early pancreatic β cell development and suggest a possible basis for the association between low diversity childhood fecal microbiota and increased diabetes risk. DOI: http://dx.doi.org/10.7554/eLife.20145.001 PMID:27960075

  20. Type 1 Diabetes Candidate Genes Linked to Pancreatic Islet Cell Inflammation and Beta-Cell Apoptosis.

    PubMed

    Størling, Joachim; Pociot, Flemming

    2017-02-16

    Type 1 diabetes (T1D) is a chronic immune-mediated disease resulting from the selective destruction of the insulin-producing pancreatic islet β-cells. Susceptibility to the disease is the result of complex interactions between environmental and genetic risk factors. Genome-wide association studies (GWAS) have identified more than 50 genetic regions that affect the risk of developing T1D. Most of these susceptibility loci, however, harbor several genes, and the causal variant(s) and gene(s) for most of the loci remain to be established. A significant part of the genes located in the T1D susceptibility loci are expressed in human islets and β cells and mounting evidence suggests that some of these genes modulate the β-cell response to the immune system and viral infection and regulate apoptotic β-cell death. Here, we discuss the current status of T1D susceptibility loci and candidate genes with focus on pancreatic islet cell inflammation and β-cell apoptosis.

  1. Targeted genetic inactivation of N-acetylglucosaminyltransferase-IVa impairs insulin secretion from pancreatic beta cells and evokes type 2 diabetes.

    PubMed

    Ohtsubo, Kazuaki

    2010-01-01

    The biological significance of protein N-glycosylation has been elucidated using a mouse model bearing a genetic mutation of N-acetylglucosaminyltransferases (GnTs), which initiate the formation of specific branch structures on the mannose core of N-glycans. These glycosylation defects evoked a variety of abnormalities and disorders in specific cell types, tissues, and the whole body, reflecting functional requirements. N-Acetylglucosaminyltransferase-IVa (GnT-IVa) initiates the GlcNAcbeta1-4 branch synthesis on the Manalpha1-3 arm of the N-glycan core thereby increasing N-glycan branch complexity. To investigate the physiological function of GnT-IVa, we engineered and characterized GnT-IVa-deficient mice. GnT-IVa-deficient mice showed a metabolic disorder subsequently diagnosed as type 2 diabetes. In this chapter, methods for characterizing GnT-IVa-deficient mice by physiological analyses to detect metabolic alterations and biochemical analyses using primary isolated pancreatic beta cells are summarized and discussed.

  2. Low plasma adiponectin level, white blood cell count and Helicobacter pylori titre independently predict abnormal pancreatic beta-cell function.

    PubMed

    So, Wing-Yee; Tong, Peter C; Ko, Gary T; Ma, Ronald C; Ozaki, Risa; Kong, Alice P; Yang, Xilin; Ho, Chung-Shun; Lam, Christopher C; Chan, Juliana C

    2009-11-01

    Adiponectin is an adipocytokine with insulin sensitizing effect while chronic inflammation damages pancreatic beta-cells leading to reduced insulin response. We aimed to prove the hypothesis that adiponectin levels and inflammatory markers (white blood cell counts [WCC], Helicobacter pylori [HP] titers, high sensitivity C-reactive protein [hs-CRP]) may interact to affect risk of diabetes. We studied 288 Chinese men (age-median: 41.0 years, IQR: 35.3-46.0 years) being recruited from the community in Hong Kong. The mean adiponectin level was 5.39+/-2.81 microg/ml and 40.9% (n=107) had low adiponectin level (<4 microg/ml). On multiple regression analysis, adiponectin was negatively associated with diabetes, HOMA insulin resistance top quartile, plasma glucose (PG) and 2h insulin; and positively associated with HOMA insulin sensitivity index. WCC was independently associated with PG and 15' insulin, and negatively associated with HOMA insulin sensitivity top quartile. HP titre was associated with 30' PG level and diabetes. hs-CRP did not enter the multivariable model. In conclusion, adiponectin, WCC and HP titer are independent predictors for hyperglycemia and reduced insulin sensitivity in Chinese men. These findings may explain the high risk for diabetes in Chinese population despite their relatively low adiposity.

  3. Reversal of beta-cell suppression in vitro in pancreatic islets isolated from nonobese diabetic mice during the phase preceding insulin-dependent diabetes mellitus.

    PubMed Central

    Strandell, E; Eizirik, D L; Sandler, S

    1990-01-01

    Insulin-dependent diabetes mellitus (IDDM) is characterized by a progressive autoimmune destruction of the pancreatic beta-cells. One of the best-suited animal models for IDDM is the nonobese diabetic (NOD) mouse. In this investigation pancreatic islets were isolated from female NOD mice aged 5-7, 8-11, and 12-13 wk and examined immediately (day 0) or after 7 d of culture (day 7). The mice showed a progressive disturbance in glucose tolerance with age, and a correspondingly increased frequency of pancreatic insulitis. Islets isolated from the oldest mice often contained inflammatory cells on day 0, which resulted in an elevated islet DNA content. During culture these islets became depleted of infiltrating cells and the DNA content of the islets decreased on day 7. Islets of the eldest mice failed to respond with insulin secretion to high glucose, whereas a response was observed in the other groups. After culture all groups of islets showed a markedly improved insulin secretion. Islets from the 12-13-wk-old mice displayed a lower glucose oxidation rate at 16.7 mM glucose on day 0 compared with day 7. Islet (pro)insulin and total protein biosynthesis was essentially unaffected. In conclusion, islets obtained from 12-13-wk-old NOD mice exhibit an impaired glucose metabolism, which may explain the suppressed insulin secretion observed immediately after isolation. This inhibition of beta-cell function can be reversed in vitro. Thus, there may be a stage during development of IDDM when beta-cell destruction can be counteracted and beta-cell function restored, provided the immune aggression is arrested. Images PMID:2189896

  4. Glucococorticoid-induced death of pancreatic Beta cells: an organized chaos.

    PubMed

    Rojas, Joselyn; Chávez-Castillo, Mervin; Chávez-Castillo, Mervin; Cabrera, Mayela; Cabrera, Mayela; Bermúdez, Valmore; Bermúdez, Valmore

    2015-01-31

    Glucocorticoids (GC) are renowned for their pleiotropic effects in all organ systems, their ubiquitous use in numerous clinical settings, and the abundant adverse effects they may exert, particularly in the endocrine-metabolic sphere. Although hyperglycemia and insulin resistance are well-defined GC-induced diabetogenic phenomena, an added component of direct injury to pancreatic β cells (PBC) may also participate in this scenario. Indeed, the apoptotic capacity of GC is widely recognized, and PBC do not escape this situation. No unified pathway has been characterized regarding GC-induced cell death; instead, it appears to depend on the specific machinery of each cell type, determining a great heterogeneity in GC-dependent apoptotic mechanisms among different tissues. In PBC, GC can induce the expression or activation of pro-apoptotic proteins (Bax, BAD, p38), repress anti-apoptotic proteins (Bcl-2), deactivate pro-survival mechanisms (cAMP-PKA signaling) and sensitize the cell to death induced by oxidative stress, fatty acids, hyperglycemia and cytokines. Although proliferative pathways (TGF-β, H-ras) are activated simultaneously - and an increase in PBC mass may be observed initially - pro-apoptotic and anti-proliferative mechanisms appear to eventually overcome their pro-survival counterparts, due to their synergic and aggregative action. Key molecules such as p38 and the cAMP-PKA system may be promising therapeutic targets in the prevention of GC-induced cell death.

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

    NASA Astrophysics Data System (ADS)

    Xiong, Guoxin; Xiong, Leilei; Li, Xinzhong

    2016-09-01

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

  6. A comparison of alcoholic pancreatitis in rat and man

    PubMed Central

    Sarles, H.; Lebreuil, G.; Tasso, F.; Figarella, C.; Clemente, F.; Devaux, M. A.; Fagonde, B.; Payan, H.

    1971-01-01

    Acute ethanol intoxication was studied in 38 Wistar rats, 18 on a balanced diet and 20 on a high fat diet, fed by gavage on 47% ethanol in a dosage of from 3 to 12 g/kg body weight daily for periods ranging from three to 16 days. No macroscopic changes in pancreas or liver were found in any of these animals. Histological changes (venous congestion of the pancreas, the liver, and the kidneys) were found in rats given 4 g or more per kilogram. The only difference between the findings in rats given a balanced diet and those given a high fat diet was the development of fatty livers in the latter group. Chronic ethanol intoxication was studied in 45 Wistar rats, on a balanced diet, which were given 20% ethanol freely for 20 to 30 months. More than half the animals developed pancreatic lesions very similar to those of human chronic pancreatitis. The pathological changes, in foci surrounded by normal pancreatic tissue, were a reduction in acini, duct multiplication (probably by neogenesis), protein plugs, sometimes calcified in the ducts and sclerosis. Samples of pancreatic juice from four animals exposed to ethanol contained significantly higher protein concentrations than samples taken from two control animals. Protein precipitates appeared spontaneously in the pancreatic juice of the animals exposed to ethanol, but not in that of the controls. These findings are very similar to those in alcoholic pancreatitis in man, which has thus been reproduced for the first time in experimental animals. Beta-cell adenomata of the islets of Langerhans were observed in four of the rats exposed to ethanol. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10 PMID:4329553

  7. Expression of a tumor necrosis factor alpha transgene in murine pancreatic beta cells results in severe and permanent insulitis without evolution towards diabetes

    PubMed Central

    1992-01-01

    Mice bearing a tumor necrosis factor (TNF) alpha transgene controlled by an insulin promoter developed an increasingly severe lymphocytic insulitis, apparently resulting from the induction of endothelial changes with features similar to those observed in other places of intense lymphocytic traffic. This was accompanied by dissociation of the endocrine tissue (without marked decrease in its total mass), islet fibrosis, and the development of intraislet ductules containing, by places, beta cells in their walls, suggesting a regenerative capacity. Islet disorganization and fibrosis did not result from lymphocytic infiltration, since they were also observed in SCID mice bearing the transgene. Diabetes never developed, even though a number of potentially inducing conditions were used, including the prolonged perfusion of interferon gamma and the permanent expression of a nontolerogenic viral protein on beta cells (obtained by using mice bearing two transgenes). It is concluded that (a) a slow process of TNF release in pancreatic islets induces insulitis, and may be instrumental in the insulitis resulting from local cell-mediated immune reactions, but (b) that insulitis per se is not diabetogenic, lymphocyte stimulation by cells other than beta cells being necessary to trigger extensive beta cell damage. This provides an explanation for the discrepancy between the occurrence of insulitis and that of clinical disease in autoimmune diabetes. PMID:1460428

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

    SciTech Connect

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

    2010-01-15

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

  9. Calcium pre-conditioning substitution enhances viability and glucose sensitivity of pancreatic beta-cells encapsulated using polyelectrolyte multilayer coating method

    PubMed Central

    Nikravesh, Niusha; Cox, Sophie C.; Birdi, Gurpreet; Williams, Richard L.; Grover, Liam M.

    2017-01-01

    Type I diabetics are dependent on daily insulin injections. A therapy capable of immunoisolating pancreatic beta-cells and providing normoglycaemia is an alternative since it would avoid the late complications associated with insulin use. Here, 3D-concave agarose micro-wells were used to culture robust pancreatic MIN-6 cell spheroids within 24 hours that were shown to exhibit cell-cell contact and uniform size (201 ± 2 μm). A polyelectrolyte multilayer (PEM) approach using alginate and poly-l-lysine was employed to coat cell spheroids. In comparison to conventional PEM, use of a novel Ca2+ pre-coating step enhanced beta-cells viability (89 ± 6%) and metabolic activity since it reduced the toxic effect of the cationic polymer. Pre-coating was achieved by treating MIN-6 spheroids with calcium chloride, which enabled the adhesion of anionic polymer to the cells surface. Pre-coated cells coated with four bilayers of polymers were successfully immunoisolated from FITC-mouse antibody and pro-inflammatory cytokines. Novel PEM coated cells were shown to secret significantly (P < 0.05) different amounts of insulin in response to changes in glucose concentration (2 vs. 20 mM). This work presents a 3D culture model and novel PEM coating procedure that enhances viability, maintains functionality and immunoisolates beta-cells, which is a promising step towards an alternative therapy to insulin. PMID:28240241

  10. The beta cell immunopeptidome.

    PubMed

    Dudek, Nadine L; Purcell, Anthony W

    2014-01-01

    Type 1 diabetes results from the autoimmune-mediated destruction of insulin-secreting beta cells, leading to beta cell loss and insulin deficiency. Presentation of peptides derived from beta cell proteins to autoreactive lymphocytes is critical for the development of disease, and the list of antigens recognized is increasing. A number of these proteins are found within the beta cell secretory granules, which are transiently exposed to the immune system during normal cellular function. How the interplay of environmental and genetic determinants culminates in destructive autoimmunity remains to be clearly defined. Nonconventional presentation of peptide ligands, posttranslational modification of peptides, and the role of the gut microbiome in the development of the immune system are all considered central topics in disease pathogenesis. Each of these may provide a mechanism by which presentation of antigenic peptides in the target tissue differs from presentation in the thymus, allowing autoreactive cells to escape tolerance induction. The high metabolic demand on pancreatic islets, the high concentration of granule proteins, and the susceptibility of islets to cellular stress may all contribute to the presentation of abnormal ligands in the pancreas. Moreover, the finding that small molecules can alter the repertoire of peptides presented by major histocompatibility complex molecules provides a tantalizing hypothesis for the presentation of autoantigenic peptides in the presence of microbial or endogenous metabolites. In this chapter, we provide an overview of the immunopeptidome of beta cells and the key factors that may influence presentation of beta cell antigens to the immune system.

  11. Activation of TRPV4 channel in pancreatic INS-1E beta cells enhances glucose-stimulated insulin secretion via calcium-dependent mechanisms.

    PubMed

    Skrzypski, M; Kakkassery, M; Mergler, S; Grötzinger, C; Khajavi, N; Sassek, M; Szczepankiewicz, D; Wiedenmann, B; Nowak, K W; Strowski, M Z

    2013-10-01

    Transient receptor potential channel vanilloid type 4 (TRPV4) is a Ca(2+)- and Mg(2+)-permeable cation channel that influences oxidative metabolism and insulin sensitivity. The role of TRPV4 in pancreatic beta cells is largely unknown. Here, we characterize the role of TRPV4 in controlling intracellular Ca(2+) and insulin secretion in INS-1E beta cells. Osmotic, thermal or pharmacological activation of TRPV4 caused a rapid rise of intracellular Ca(2+) and enhanced glucose-stimulated insulin secretion. In the presence of the TRPV channel blocker ruthenium red (RuR) or after suppression of TRPV4 protein production, TRPV4 activators failed to increase [Ca(2+)]i and insulin secretion in INS-1E cells.

  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.

    PubMed

    Smidt, Kamille; Larsen, Agnete; Brønden, Andreas; Sørensen, Karen S; Nielsen, Julie V; Praetorius, Jeppe; Martensen, Pia M; Rungby, Jørgen

    2016-04-01

    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 granules whereas ZNT3 knockout negatively affects beta cell function and survival. Here, we describe for the first time the sub-cellular localization of ZNT3 by immuno-gold electron microscopy and supplement previous data from knockout experiments with investigations of the effect of ZNT3 in a pancreatic beta cell line, INS-1E overexpressing ZNT3. In INS-1E cells, we found that ZNT3 was abundant in insulin containing granules located close to the plasma membrane. The level of ZNT8 mRNA was significantly decreased upon over-expression of ZNT3 at different glucose concentrations (5, 11 and 21 mM glucose). ZNT3 over-expression decreased insulin content and insulin secretion whereas ZNT3 over-expression improved the cell survival after 24 h at varying glucose concentrations (5, 11 and 21 mM). Our data suggest that ZNT3 and ZNT8 (known to regulate insulin secretion) have opposite effects on insulin synthesis and secretion possibly by a transcriptional co-regulation since mRNA expression of ZNT3 was inversely correlated to ZNT8 and ZNT3 over-expression reduced insulin synthesis and secretion in INS-1E cells. ZNT3 over-expression improved cell survival.

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

    SciTech Connect

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

    2010-07-30

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

  14. Interactome analysis of AMP-activated protein kinase (AMPK)-α1 and -β1 in INS-1 pancreatic beta-cells by affinity purification-mass spectrometry.

    PubMed

    Moon, Sungyoon; Han, Dohyun; Kim, Yikwon; Jin, Jonghwa; Ho, Won-Kyung; Kim, Youngsoo

    2014-03-14

    The heterotrimeric enzyme AMP-activated protein kinase (AMPK) is a major metabolic factor that regulates the homeostasis of cellular energy. In particular, AMPK mediates the insulin resistance that is associated with type 2 diabetes. Generally, cellular processes require tight regulation of protein kinases, which is effected through their formation of complex with other proteins and substrates. Despite their critical function in regulation and pathogenesis, there are limited data on the interaction of protein kinases. To identify proteins that interact with AMPK, we performed large-scale affinity purification (AP)-mass spectrometry (MS) of the AMPK-α1 and -β1 subunits. Through a comprehensive analysis, using a combination of immunoprecipitaion and ion trap mass spectrometry, we identified 381 unique proteins in the AMPKα/β interactomes: 325 partners of AMPK-α1 and 243 for AMPK-β1. Further, we identified 196 novel protein-protein interactions with AMPK-α1 and AMPK-β1. Notably, in our bioinformatics analysis, the novel interaction partners mediated functions that are related to the regulation of actin organization. Specifically, several such proteins were linked to pancreatic beta-cell functions, including glucose-stimulated insulin secretion, beta-cell development, beta-cell differentiation, and cell-cell communication.

  15. Different modes of action of the imidazoline compound RX871024 in pancreatic beta-cells. Blocking of K+ channels, mobilization of Ca2+ from endoplasmic reticulum, and interaction with exocytotic machinery.

    PubMed

    Zaitsev, S V; Efanov, A M; Raap, A; Efanova, I B; Schloos, J; Steckel-Hamann, B; Larsson, O; Ostenson, C G; Berggren, P O; Mest, H J; Efendic, S

    1999-06-21

    The imidazoline compound RX871024 glucose-dependently potentiates the release of insulin in pancreatic islets and beta-cell lines. This activity of the compound is not related to its action by stimulating alpha 2-adrenoceptors and I1- and I2-imidazoline receptors. There are at least three modes of action of RX871024 in beta-cells: (1) RX871024 blocks the ATP-dependent, Ca(2+)-activated, and delayed rectifier K+ channel activity; (2) RX871024 causes mobilization of Ca2+ from thapsigargin-sensitive intracellular stores, the effect probably controlled by cytochrome P450; and (3) the stimulatory activity of RX871024 on insulin release involves interaction of the compound with the exocytotic machinery, unrelated to the changes in membrane potential and cytoplasmic-free Ca2+ concentration, whereas protein phosphorylation plays an important role in this process. The maximal insulinotropic effect of RX871024 is much higher than that of the sulfonylurea glibenclamide. RX871024 stimulates insulin release and normalizes blood glucose levels in rats in vivo without affecting blood pressure and heart rate.

  16. Carriers of Loss-of-Function Mutations in EXT Display Impaired Pancreatic Beta-Cell Reserve Due to Smaller Pancreas Volume

    PubMed Central

    Hassing, H . Carlijne; Kruit, Janine K.; Witjes, Julia J.; van de Sande, Michiel A. J.; Nederveen, Aart J.; Xu, Ding; Dallinga-Thie, Geesje M.; Esko, Jeffrey D.; Stroes, Erik S. G.; Nieuwdorp, Max

    2014-01-01

    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. PMID:25541963

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

    PubMed Central

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

    2015-01-01

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

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

    SciTech Connect

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

    2012-08-24

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

  19. Double-stranded RNA cooperates with interferon-gamma and IL-1 beta to induce both chemokine expression and nuclear factor-kappa B-dependent apoptosis in pancreatic beta-cells: potential mechanisms for viral-induced insulitis and beta-cell death in type 1 diabetes mellitus.

    PubMed

    Liu, Dongbo; Cardozo, Alessandra K; Darville, Martine I; Eizirik, Décio L

    2002-04-01

    Viral infections may trigger the autoimmune assault leading to type 1 diabetes mellitus. Double-stranded RNA (dsRNA) is produced by many viruses during their replicative cycle. The dsRNA, tested as synthetic poly(IC) (PIC), in synergism with the proinflammatory cytokines interferon-gamma (IFN-gamma) and/or IL-1 beta, results in nitric oxide production, Fas expression, beta-cell dysfunction, and death. Activation of the transcription nuclear factor-kappa B (NF-kappa B) is required for PIC-induced inducible nitric oxide synthase expression in beta-cells, and we hypothesized that this transcription factor may also participate in PIC-induced Fas expression and beta-cell apoptosis. This hypothesis, and the possibility that PIC induces expression of additional chemokines and cytokines (previously reported as NF-kappa B dependent) in pancreatic beta-cells, was investigated in the present study. We observed that the PIC-responsive region in the Fas promoter is located between nucleotides -223 and -54. Site-directed mutations at the NF-kappa B and CCAAT/enhancer binding protein-binding sites prevented PIC-induced Fas promoter activity. Increased Fas promoter activity was paralleled by enhanced susceptibility of PIC + cytokine-treated beta-cells to apoptosis induced by Fas ligand. beta-Cell infection with the NF-kappa B inhibitor AdI kappa B((SA)2) prevented both necrosis and apoptosis induced by PIC + IL-1 beta or PIC + IFN-gamma. Messenger RNAs for several chemokines and one cytokine were induced by PIC, alone or in combination with IFN-gamma, in pancreatic beta-cells. These included IP-10, interferon-gamma-inducible protein-10, IL-15, macrophage chemoattractant protein-1, fractalkine, and macrophage inflammatory protein-3 alpha. There was not, however, induction of IL-1 beta expression. We propose that dsRNA, generated during a viral infection, may contribute for beta-cell demise by both inducing expression of chemokines and IL-15, putative contributors for the build

  20. Pancreatic Fat Is Associated With Metabolic Syndrome and Visceral Fat but Not Beta-Cell Function or Body Mass Index in Pediatric Obesity

    PubMed Central

    Staaf, Johan; Labmayr, Viktor; Paulmichl, Katharina; Manell, Hannes; Cen, Jing; Ciba, Iris; Dahlbom, Marie; Roomp, Kirsten; Anderwald, Christian-Heinz; Meissnitzer, Matthias; Schneider, Reinhard; Forslund, Anders; Widhalm, Kurt; Bergquist, Jonas; Ahlström, Håkan; Bergsten, Peter; Weghuber, Daniel; Kullberg, Joel

    2017-01-01

    Objective Adolescents with obesity have increased risk of type 2 diabetes and metabolic syndrome (MetS). Pancreatic fat has been related to these conditions; however, little is known about associations in pediatric obesity. The present study was designed to explore these associations further. Methods We examined 116 subjects, 90 with obesity. Anthropometry, MetS, blood samples, and oral glucose tolerance tests were assessed using standard techniques. Pancreatic fat fraction (PFF) and other fat depots were quantified using magnetic resonance imaging. Results The PFF was elevated in subjects with obesity. No association between PFF and body mass index-standard deviation score (BMI-SDS) was found in the obesity subcohort. Pancreatic fat fraction correlated to Insulin Secretion Sensitivity Index-2 and Homeostatic Model Assessment of Insulin Resistance in simple regression; however, when using adjusted regression and correcting for BMI-SDS and other fat compartments, PFF correlated only to visceral adipose tissue and fasting glucose. Highest levels of PFF were found in subjects with obesity and MetS. Conclusions In adolescents with obesity, PFF is elevated and associated to MetS, fasting glucose, and visceral adipose tissue but not to beta-cell function, glucose tolerance, or BMI-SDS. This study demonstrates that conclusions regarding PFF and its associations depend on the body mass features of the cohort. PMID:27941426

  1. The endoplasmic reticulum stress response is stimulated through the continuous activation of transcription factors ATF6 and XBP1 in Ins2+/Akita pancreatic beta cells.

    PubMed

    Nozaki, Jun ichi; Kubota, Hiroshi; Yoshida, Hiderou; Naitoh, Motoko; Goji, Junko; Yoshinaga, Takeo; Mori, Kazutoshi; Koizumi, Akio; Nagata, Kazuhiro

    2004-03-01

    The dominant C96Y mutation of one of the two murine insulin genes, Ins2, causes diabetes mellitus in 'Akita' mice. Here we established pancreatic islet beta cell lines from heterozygous mice (Ins2+/Akita). Western blot analysis of endoplasmic reticulum (ER) molecular chaperones indicated that Grp78, Grp94 and Orp150 are significantly increased in Ins2+/Akita cells compared with wild-type (Ins2+/+) cells. Reporter gene assays using the human GRP78 promoter with or without the ER stress response element (ERSE) showed that Ins2+/Akita cells exhibit significantly stronger ERSE-dependent transcriptional activity than Ins2+/+ cells. Transient over-expression of the Ins2 C96Y mutant in wild-type beta cells induces a stronger ERSE-dependent stress response than does wild-type Ins2 over-expression. The ERSE-binding transcription factor ATF6 is strongly activated in Ins2+/Akita cells. The activity of a reporter containing the specific binding sequence of another ERSE-binding transcription factor, XBP1, is also enhanced in Ins2+/Akita cells. Levels of active forms of XBP1 mRNA and protein are both markedly elevated in Ins2+/Akita cells. These results indicate that this cell line is subject to continuous ER stress and that the Ins2 C96Y mutation induces the expression of ER chaperones through the activation of ATF6 and XBP1.

  2. Co-encapsulation of bioengineered IGF-II-producing cells and pancreatic islets: effect on beta-cell survival.

    PubMed

    Jourdan, G; Dusseault, J; Benhamou, P Y; Rosenberg, L; Hallé, J P

    2011-06-01

    Insulin-like growth factor-II (IGF-II) has been shown to promote pancreatic β-cell survival. We evaluated the effect of co-encapsulating islets and bioengineered IGF-II-producing cells on islet cell survival. IGF-II or green fast protein (GFP) genes were transferred into TM4 cells, and purified using a neomycin resistance gene, leading to pure cell cultures (TM4-IGF-II or TM4-GFP) with a stable overexpression of the transferred gene. Islets were co-encapsulated with TM4-IGF-II or TM4-GFP, or encapsulated alone in alginate microcapsules. Rat and mouse islet cell survival was studied in vitro and in vivo, respectively. After 12 days in culture, islet viability (dual staining, acridine orange/propidium iodide) was 83% with TM4-IGF-II, compared with 51% (P<0.05) and 41% (P<0.001) with TM4-GFP and islets alone, respectively. The study of islet necrotic centers and the evaluation of islet function, using the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) assay, yielded similar results. From 125 days after transplantation, more diabetic mice maintained normoglycemia when they were transplanted with islets co-encapsulated with TM4-IGF-II (4/7). A significant difference for the maintenance of normoglycemia was observed between recipients of islets co-encapsulated with TM4-IGF-II versus islets alone (P=0.023), or with TM4-GFP (P=0.048). In conclusion, the co-encapsulation of islets with bioengineered IGF-II-producing cells promotes islet cell survival.

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

    PubMed

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

    2015-10-09

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

  4. Would R.D. Lawrence have been interested in the regulation of insulin secretion from pancreatic beta-cells?

    PubMed

    Jones, P M

    1998-08-01

    Dr Peter Jones gave the 1997 R.D. Lawrence Lecture to the Medical and Scientific Section of the British Diabetic Association. This prestigious award, made to an outstanding young researcher, is named in honour of the man who, with H.G. Wells, founded the British Diabetic Association, and was given to Dr Jones in acknowledgment of his work in the field of islet cell physiology and pathophysiology. In this article, Dr Jones recalls his lecture and describes the principles of intracellular signalling in insulin secretion and the need for beta-cells to live together.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2015-01-01

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

  8. Glucose- and GTP-dependent stimulation of the carboxyl methylation of CDC42 in rodent and human pancreatic islets and pure beta cells. Evidence for an essential role of GTP-binding proteins in nutrient-induced insulin secretion.

    PubMed Central

    Kowluru, A; Seavey, S E; Li, G; Sorenson, R L; Weinhaus, A J; Nesher, R; Rabaglia, M E; Vadakekalam, J; Metz, S A

    1996-01-01

    Several GTP-binding proteins (G-proteins) undergo post-translational modifications (isoprenylation and carboxyl methylation) in pancreatic beta cells. Herein, two of these were identified as CDC42 and rap 1, using Western blotting and immunoprecipitation. Confocal microscopic data indicated that CDC42 is localized only in islet endocrine cells but not in acinar cells of the pancreas. CDC42 undergoes a guanine nucleotide-specific membrane association and carboxyl methylation in normal rat islets, human islets, and pure beta (HIT or INS-1) cells. GTPgammaS-dependent carboxyl methylation of a 23-kD protein was also demonstrable in secretory granule fractions from normal islets or beta cells. AFC (a specific inhibitor of prenyl-cysteine carboxyl methyl transferases) blocked the carboxyl methylation of CDC42 in five types of insulin-secreting cells, without blocking GTPgammaS-induced translocation, implying that methylation is a consequence (not a cause) of transfer to membrane sites. High glucose (but not a depolarizing concentration of K+) induced the carboxyl methylation of CDC42 in intact cells, as assessed after specific immunoprecipitation. This effect was abrogated by GTP depletion using mycophenolic acid and was restored upon GTP repletion by coprovision of guanosine. In contrast, although rap 1 was also carboxyl methylated, it was not translocated to the particulate fraction by GTPgammaS; furthermore, its methylation was also stimulated by 40 mM K+ (suggesting a role which is not specific to nutrient stimulation). AFC also impeded nutrient-induced (but not K+-induced) insulin secretion from islets and beta cells under static or perifusion conditions, whereas an inactive structural analogue of AFC failed to inhibit insulin release. These effects were reproduced not only by S-adenosylhomocysteine (another methylation inhibitor), but also by GTP depletion. Thus, the glucose- and GTP-dependent carboxyl methylation of G-proteins such as CDC42 is an obligate step in

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    PubMed Central

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

    2014-01-01

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

  11. Notch signaling: a mediator of beta-cell de-differentiation in diabetes?

    PubMed

    Darville, Martine I; Eizirik, Décio L

    2006-01-27

    Cytokines are mediators of pancreatic beta-cell dysfunction and death in type 1 diabetes mellitus. Microarray analyses of insulin-producing cells exposed to interleukin-1beta+interferon-gamma showed decreased expression of genes related to beta-cell-differentiated functions and increased expression of members of the Notch signaling pathway. Re-expression of this developmental pathway may contribute for loss-of-function of beta-cells exposed to an autoimmune attack. In this study, we show that rat primary beta-cells exposed to cytokines up-regulate several Notch receptors and ligands, and the target gene Hes1. Transfection of insulin-producing INS-1E cells and primary rat beta-cells with a constitutively active form of the Notch receptor down-regulated Pdx1 and insulin expression in INS-1E cells but not in primary beta-cells. Thus, activation of the Notch pathway inhibits differentiated functions in dividing but not in terminally differentiated beta-cells.

  12. Regulation of glucose- and mitochondrial fuel-induced insulin secretion by a cytosolic protein histidine phosphatase in pancreatic beta-cells.

    PubMed

    Kamath, Vasudeva; Kyathanahalli, Chandrashekara N; Jayaram, Bhavaani; Syed, Ismail; Olson, Lawrence Karl; Ludwig, Katrin; Klumpp, Susanne; Krieglstein, Josef; Kowluru, Anjaneyulu

    2010-08-01

    We report localization of a cytosolic protein histidine phosphatase (PHP; approximately 16 kDa) in INS 832/13 cells, normal rat islets, and human islets. siRNA-mediated knockdown of PHP markedly reduced glucose- or mitochondrial fuel-induced but not KCl-induced insulin secretion. siRNA-mediated knockdown of PHP also attenuated mastoparan-induced insulin secretion, suggesting its participation in G protein-sensitive signaling steps, leading to insulin secretion. Functional assays revealed that the beta-cell PHP catalyzes the dephosphorylation of ATP-citrate lyase (ACL). Silencing of PHP expression markedly reduced ACL activity, suggesting functional regulation of ACL by PHP in beta-cells. Coimmunoprecipitation studies revealed modest effects of glucose on the interaction between PHP and ACL. Confocal microscopic evidence indicated that glucose promotes association between ACL and nm23-H1, a known kinase histidine kinase, but not between PHP and ACL. Furthermore, metabolic viability of INS 832/13 cells was resistant to siRNA-PHP, suggesting no regulatory roles of PHP in cell viability. Finally, long-term exposure (24 h) of INS 832/13 cells or rat islets to high glucose (30 mM) increased the expression of PHP. Such increases in PHP expression were also seen in islets derived from the Zucker diabetic fatty rat compared with islets from the lean control animals. Together, these data implicate regulatory roles for PHP in a G protein-sensitive step involved in nutrient-induced insulin secretion. In light of the current debate on putative regulatory roles of ACL in insulin secretion, additional studies are needed to precisely identify the phosphoprotein substrate(s) for PHP in the cascade of events leading to nutrient-induced insulin secretion.

  13. Pinealectomy aggravates acute pancreatitis in the rat.

    PubMed

    Jaworek, Jolanta; Zwirska-Korczala, Krystyna; Szklarczyk, Joanna; Nawrot-Porąbka, Katarzyna; Leja-Szpak, Anna; Jaworek, Andrzej K; Tomaszewska, Romana

    2010-01-01

    Melatonin, a pineal indoleamine, protects the pancreas against acute damage; however, the involvement of the pineal gland in the pancreatoprotective action of melatonin is unknown. The primary aim of this study was to determine the effects of pinealectomy on the course of acute caerulein-induced pancreatitis (AP) in rats. AP was induced by a subcutaneous infusion of caerulein (25 μg/kg) into pinealectomized or sham-operated animals. Melatonin (5 or 25 mg/kg) was given via intraperitoneal (ip) injection 30 min prior to the induction of AP. The pancreatic content of the lipid peroxidation products malondialdehyde and 4-hydroxynonenal (MDA + 4HNE) and the activity of an antioxidative enzyme, glutathione peroxidase (GSH-Px), were measured in each group of rats. Melatonin blood levels were measured by radioimmunoassay (RIA). In the sham-operated rats, AP was confirmed with histological examination and manifested as pancreatic edema and an increase in the blood lipase level (by 1,500%). In addition, the pancreatic content of MDA+ 4HNE was increased by 200%, and pancreatic glutathione peroxydase (GSH-Px) activity was reduced by 40%. Pinealectomy significantly aggravated the histological manifestations of AP, reduced the GSH-Px activity and markedly augmented the levels of MDA+ 4HNE in the pancreas of rats with or without AP as compared to sham-operated animals. Melatonin was undetectable in the blood of the pinealectomized rats with or without AP. Treatment with melatonin (25 mg/kg, ip) prevented the development of AP in the sham-operated rats and significantly reduced pancreatic inflammation in the animals previously subjected to pinealectomy. In conclusion, pineal melatonin contributes to the pancreatic protection through the activation of the antioxidative defense mechanism in pancreatic tissue as well as its direct antioxidant effects.

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

    PubMed

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

    2000-11-01

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

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

    SciTech Connect

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

    2009-07-31

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

  16. ChREBP mediates glucose repression of peroxisome proliferator-activated receptor alpha expression in pancreatic beta-cells.

    PubMed

    Boergesen, Michael; Poulsen, Lars la Cour; Schmidt, Søren Fisker; Frigerio, Francesca; Maechler, Pierre; Mandrup, Susanne

    2011-04-15

    Chronic exposure to elevated levels of glucose and fatty acids leads to dysfunction of pancreatic β-cells by mechanisms that are only partly understood. The transcription factor peroxisome proliferator-activated receptor α (PPARα) is an important regulator of genes involved in fatty acid metabolism and has been shown to protect against lipid-induced β-cell dysfunction. We and others have previously shown that expression of the PPARα gene in β-cells is rapidly repressed by glucose. Here we show that the PPARα gene is transcribed from five alternative transcription start sites, resulting in three alternative first exons that are spliced to exon 2. Expression of all PPARα transcripts is repressed by glucose both in insulinoma cells and in isolated pancreatic islets. The observation that the dynamics of glucose repression of PPARα transcription are very similar to those of glucose activation of target genes by the carbohydrate response element-binding protein (ChREBP) prompted us to investigate the potential role of ChREBP in the regulation of PPARα expression. We show that a constitutively active ChREBP lacking the N-terminal domain efficiently represses PPARα expression in insulinoma cells and in rodent and human islets. In addition, we demonstrate that siRNA-mediated knockdown of ChREBP abrogates glucose repression of PPARα expression as well as induction of well established ChREBP target genes in insulinoma cells. In conclusion, this work shows that ChREBP is a critical and direct mediator of glucose repression of PPARα gene expression in pancreatic β-cells, suggesting that ChREBP may be important for glucose suppression of the fatty acid oxidation capacity of β-cells.

  17. Glucoregulatory endocrine responses to intermittent exercise of different intensities: plasma changes in a pancreatic beta-cell peptide, amylin.

    PubMed

    Kraemer, R R; Acevedo, E O; Synovitz, L B; Durand, R J; Johnson, L G; Petrella, E; Fineman, M S; Gimpel, T; Castracane, V D

    2002-05-01

    Amylin, a peptide hormone released from the beta cells of the pancreas and cosecreted with insulin, is reported to inhibit the release of postprandial glucagon and insulin and to modulate gastric emptying. Changes in insulin and glucagon are important for controlling blood glucose levels under conditions in which metabolic rate is elevated, such as during and following exercise. Amylin may participate in the regulation of blood glucose levels in response to exercise, although the role of amylin has not been investigated. The purpose of the study was to determine the effects of a progressive, intermittent exercise protocol on amylin concentrations and to compare its response to circulating levels of insulin, glucagon, cortisol, and glucose. Seven well-trained males completed an intermittent exercise trial on a treadmill at four progressive exercise intensities: 60%, 75%, 90%, and 100% of maximum oxygen consumption (.VO(2)max). Blood samples were collected before exercise, after each exercise intensity, and for 1 hour following the exercise protocol. Subjects also completed a control trial with no exercise. Amylin and insulin rose from baseline (5.79 +/-.78 pmol/L and 4.76 +/-.88 microIU/mL) to peak after 100% .VO(2)max (9.16 +/- 1.35 pmol/L and 14.37 +/- microIU/ml), respectively and remained elevated during much of recovery. Thus, a progressive intermittent exercise protocol of moderate to maximum exercise intensities stimulates increases in amylin levels in well-trained individuals in a similar fashion to that of insulin, whereas glucagon concentrations only increase after the greatest exercise intensity, then quickly decline. Future studies should examine the effects of higher amylin concentrations in exercise recovery on glucoregulation.

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

    PubMed Central

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

    2016-01-01

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

  19. Ubiquitin fold modifier 1 (UFM1) and its target UFBP1 protect pancreatic beta cells from ER stress-induced apoptosis.

    PubMed

    Lemaire, Katleen; Moura, Rodrigo F; Granvik, Mikaela; Igoillo-Esteve, Mariana; Hohmeier, Hans E; Hendrickx, Nico; Newgard, Christopher B; Waelkens, Etienne; Cnop, Miriam; Schuit, Frans

    2011-04-06

    UFM1 is a member of the ubiquitin like protein family. While the enzymatic cascade of UFM1 conjugation has been elucidated in recent years, the biological function remains largely unknown. In this report we demonstrate that the recently identified C20orf116, which we name UFM1-binding protein 1 containing a PCI domain (UFBP1), and CDK5RAP3 interact with UFM1. Components of the UFM1 conjugation pathway (UFM1, UFBP1, UFL1 and CDK5RAP3) are highly expressed in pancreatic islets of Langerhans and some other secretory tissues. Co-localization of UFM1 with UFBP1 in the endoplasmic reticulum (ER) depends on UFBP1. We demonstrate that ER stress, which is common in secretory cells, induces expression of Ufm1, Ufbp1 and Ufl1 in the beta-cell line INS-1E. siRNA-mediated Ufm1 or Ufbp1 knockdown enhances apoptosis upon ER stress. Silencing the E3 enzyme UFL1, results in similar outcomes, suggesting that UFM1-UFBP1 conjugation is required to prevent ER stress-induced apoptosis. Together, our data suggest that UFM1-UFBP1 participate in preventing ER stress-induced apoptosis in protein secretory cells.

  20. Ubiquitin Fold Modifier 1 (UFM1) and Its Target UFBP1 Protect Pancreatic Beta Cells from ER Stress-Induced Apoptosis

    PubMed Central

    Granvik, Mikaela; Igoillo-Esteve, Mariana; Hohmeier, Hans E.; Hendrickx, Nico; Newgard, Christopher B.; Waelkens, Etienne; Cnop, Miriam; Schuit, Frans

    2011-01-01

    UFM1 is a member of the ubiquitin like protein family. While the enzymatic cascade of UFM1 conjugation has been elucidated in recent years, the biological function remains largely unknown. In this report we demonstrate that the recently identified C20orf116 [1], which we name UFM1-binding protein 1 containing a PCI domain (UFBP1), andCDK5RAP3 interact with UFM1. Components of the UFM1 conjugation pathway (UFM1, UFBP1, UFL1 and CDK5RAP3) are highly expressed in pancreatic islets of Langerhans and some other secretory tissues. Co-localization of UFM1 with UFBP1 in the endoplasmic reticulum (ER)depends on UFBP1. We demonstrate that ER stress, which is common in secretory cells, induces expression of Ufm1, Ufbp1 and Ufl1 in the beta-cell line INS-1E.siRNA-mediated Ufm1 or Ufbp1knockdown enhances apoptosis upon ER stress.Silencing the E3 enzyme UFL1, results in similar outcomes, suggesting that UFM1-UFBP1 conjugation is required to prevent ER stress-induced apoptosis. Together, our data suggest that UFM1-UFBP1participate in preventing ER stress-induced apoptosis in protein secretory cells. PMID:21494687

  1. Potentiation of Calcium Influx and Insulin Secretion in Pancreatic Beta Cell by the Specific TREK-1 Blocker Spadin

    PubMed Central

    Hivelin, Céline; Béraud-Dufour, Sophie; Devader, Christelle; Moreno, Sébastien; Moha ou Maati, Hamid; Djillani, Alaeddine; Heurteaux, Catherine; Borsotto, Marc

    2016-01-01

    Inhibition of the potassium channels TREK-1 by spadin (SPA) is currently thought to be a promising therapeutic target for the treatment of depression. Since these channels are expressed in pancreatic β-cells, we investigated their role in the control of insulin secretion and glucose homeostasis. In this study, we confirmed the expression of TREK-1 channels in the insulin secreting MIN6-B1 β-cell line and in mouse islets. We found that their blockade by SPA potentiated insulin secretion induced by potassium chloride dependent membrane depolarization. Inhibition of TREK-1 by SPA induced a decrease of the resting membrane potential (ΔVm ~ 12 mV) and increased the cytosolic calcium concentration. In mice, administration of SPA enhanced the plasma insulin level stimulated by glucose, confirming its secretagogue effect observed in vitro. Taken together, this work identifies SPA as a novel potential pharmacological agent able to control insulin secretion and glucose homeostasis. PMID:28105440

  2. Potentiation of Calcium Influx and Insulin Secretion in Pancreatic Beta Cell by the Specific TREK-1 Blocker Spadin.

    PubMed

    Hivelin, Céline; Béraud-Dufour, Sophie; Devader, Christelle; Abderrahmani, Amar; Moreno, Sébastien; Moha Ou Maati, Hamid; Djillani, Alaeddine; Heurteaux, Catherine; Borsotto, Marc; Mazella, Jean; Coppola, Thierry

    2016-01-01

    Inhibition of the potassium channels TREK-1 by spadin (SPA) is currently thought to be a promising therapeutic target for the treatment of depression. Since these channels are expressed in pancreatic β-cells, we investigated their role in the control of insulin secretion and glucose homeostasis. In this study, we confirmed the expression of TREK-1 channels in the insulin secreting MIN6-B1 β-cell line and in mouse islets. We found that their blockade by SPA potentiated insulin secretion induced by potassium chloride dependent membrane depolarization. Inhibition of TREK-1 by SPA induced a decrease of the resting membrane potential (ΔVm ~ 12 mV) and increased the cytosolic calcium concentration. In mice, administration of SPA enhanced the plasma insulin level stimulated by glucose, confirming its secretagogue effect observed in vitro. Taken together, this work identifies SPA as a novel potential pharmacological agent able to control insulin secretion and glucose homeostasis.

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

    PubMed

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

    2016-01-01

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

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

    PubMed

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

    2004-01-01

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

  5. Amino acid sequence of TsTX-V, an alpha-toxin from Tityus serrulatus scorpion venom, and its effect on K+ permeability of beta-cells from isolated rat islets of Langerhans.

    PubMed

    Marangoni, S; Toyama, M H; Arantes, E C; Giglio, J R; da Silva, C A; Carneiro, E M; Gonçalves, A A; Oliveira, B

    1995-04-13

    Highly purified Tityustoxin V (TsTX-V), an alpha-toxin isolated from the venom of the Brazilian scorpion Tityus serrulatus, was obtained by ion exchange chromatography on carboxymethylcellulose-52. It was shown to be homogeneous by reverse phase high performance liquid chromatography, N-terminal sequencing (first 39 residues) of the reduced and alkylated protein and by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate and tricine. Following enzymatic digestion, the complete amino acid sequence (64 residues) was determined. The sequence showed higher homology with the toxins from the venoms of the North African than with those of the North and South American scorpions. Using the rate of 86Rb+ release from depolarized rat pancreatic beta-cells as a measure of K+ permeability changes, TsTX-V (5.6 micrograms/ml) was found to increase by 2.0-2.4-fold the rate of marker outflow in the presence of 8.3 mM glucose. This effect was persistent and slowly reversible, showing similarity to that induced by 100 microM veratridine, an agent that increases the open period of Na+ channels, delaying their inactivation. It is suggested that, by extending the depolarized period, TsTX-V indirectly affects beta-cell voltage-dependent K+ channels, thus increasing K+ permeability.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

    Type 1 diabetes mellitus (T1D) is characterized by a heightened antibody (Ab) response to pancreatic islet self-antigens, which is a biomarker of progressive islet pathology. We recently identified a novel antibody to clade B serpin that reduces islet-associated T cell accumulation and is linked to the delayed onset of T1D. As natural immunity to clade B arises early in life, we hypothesized that it may influence islet development during that time. To test this possibility healthy young Balb/c male mice were injected with serpin B13 mAb or IgG control and examined for the number and cellularity of pancreatic islets by immunofluorescence and FACS. Beta cell proliferation was assessed by measuring nucleotide analog 5-ethynyl-2′-deoxyuridine (5-EdU) incorporation into the DNA and islet Reg gene expression was measured by real time PCR. Human studies involved measuring anti-serpin B13 autoantibodies by Luminex. We found that injecting anti-serpin B13 monoclonal Ab enhanced beta cell proliferation and Reg gene expression, induced the generation of ∼80 pancreatic islets per animal, and ultimately led to increase in the beta cell mass. These findings are relevant to human T1D because our analysis of subjects just diagnosed with T1D revealed an association between baseline anti-serpin activity and slower residual beta cell function decline in the first year after the onset of diabetes. Our findings reveal a new role for the anti-serpin immunological response in promoting adaptive changes in the endocrine pancreas and suggests that enhancement of this response could potentially help impede the progression of T1D in humans. PMID:26578518

  9. The Toll-Like Receptor Signaling Molecule Myd88 Contributes to Pancreatic Beta-Cell Homeostasis in Response to Injury

    PubMed Central

    Bollyky, Paul L.; Bice, Jeffrey B.; Sweet, Ian R.; Falk, Ben A.; Gebe, John A.; Clark, April E.; Gersuk, Vivian H.; Aderem, Alan; Hawn, Thomas R.; Nepom, Gerald T.

    2009-01-01

    Commensal flora and pathogenic microbes influence the incidence of diabetes in animal models yet little is known about the mechanistic basis of these interactions. We hypothesized that Myd88, an adaptor molecule in the Toll-like-receptor (TLR) pathway, regulates pancreatic β-cell function and homeostasis. We first examined β-cells histologically and found that Myd88−/− mice have smaller islets in comparison to C57Bl/6 controls. Myd88−/− mice were nonetheless normoglycemic both at rest and after an intra-peritoneal glucose tolerance test (IPGTT). In contrast, after low-dose streptozotocin (STZ) challenge, Myd88−/−mice had an abnormal IPGTT relative to WT controls. Furthermore, Myd88−/− mice suffer enhanced β-cell apoptosis and have enhanced hepatic damage with delayed recovery upon low-dose STZ treatment. Finally, we treated WT mice with broad-spectrum oral antibiotics to deplete their commensal flora. In WT mice, low dose oral lipopolysaccharide, but not lipotichoic acid or antibiotics alone, strongly promoted enhanced glycemic control. These data suggest that Myd88 signaling and certain TLR ligands mediate a homeostatic effect on β-cells primarily in the setting of injury. PMID:19357791

  10. Role of pterostilbene in attenuating immune mediated devastation of pancreatic beta cells via Nrf2 signaling cascade.

    PubMed

    Sireesh, Dornadula; Ganesh, Munuswamy-Ramanujam; Dhamodharan, Umapathy; Sakthivadivel, Murugesan; Sivasubramanian, Srinivasan; Gunasekaran, Palani; Ramkumar, Kunka Mohanram

    2017-03-06

    Nrf2 (nuclear factor erythroid 2-related factor-2) is a transcription factor that regulates oxidative/xenobiotic stress response and also suppress inflammation. Nrf2 signaling is associated with an increased susceptibility to various kinds of stress. Nrf2 has been shown as a promising therapeutic target in various human diseases including diabetes. Our earlier studies showed Pterostilbene (PTS) as a potent Nrf2 activator, and it protects the pancreatic β-cells against oxidative stress. In this study, we investigated PTS confer protection against cytokine-induced β-cell apoptosis and its role on insulin secretion in streptozotocin (STZ)-induced diabetic mice. The Nrf2 activation potential of PTS was assessed by dissociation of the Nrf2-Keap1 complex and by expression of ARE-driven downstream target genes in MIN6 cells. Further, the nuclear Nrf2 translocation and blockage of apoptotic signaling as demonstrated by the reduction of BAX/Bcl-2 ratio, Annexin-V positive cells and caspase-3 activity conferred the cyto-protection of PTS against cytokine-induced cellular damage. In addition, PTS treatment markedly improved glucose homeostasis and abated inflammatory response evidenced by the reduction of proinflammatory cytokines in diabetic mice. The inhibition of β-cell apoptosis by PTS as assessed by BAX/Bcl-2 ratio and caspase-3 activity in the pancreas was associated with the activation of Nrf2 and the expression of its downstream target genes. PTS also inhibited the activation of iNOS and decreased nitric oxide (NO) formation in the pancreas of diabetic animals. The results obtained from both in vitro and in vivo experiments showed that PTS improves β-cell function and survival against cytokine stress and also prevents STZ-induced diabetes.

  11. Positive Feedback Amplifies the Response of Mitochondrial Membrane Potential to Glucose Concentration in Clonal Pancreatic Beta Cells.

    PubMed

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

    2016-10-20

    Analysis of the cellular mechanisms of metabolic disorders, including type 2 diabetes mellitus, is complicated by the large number of reactions and interactions in metabolic networks. Metabolic control analysis with appropriate modularization is a powerful method for simplifying and analyzing these networks. To analyze control of cellular energy metabolism in adherent cell cultures of the INS-1 832/13 pancreatic β-cell model we adapted our microscopy assay of absolute mitochondrial membrane potential (ΔψM) to a fluorescence microplate reader format, and applied it in conjunction with cell respirometry. In these cells the sensitive response of ΔψM to extracellular glucose concentration drives glucose-stimulated insulin secretion. Using metabolic control analysis we identified the control properties that generate this sensitive response. Force-flux relationships between ΔψM and respiration were used to calculate kinetic responses to ΔψM of processes both upstream (glucose oxidation) and downstream (proton leak and ATP turnover) of ΔψM. The analysis revealed that glucose-evoked ΔψM hyperpolarization is amplified by increased glucose oxidation activity caused by factors downstream of ΔψM. At high glucose, the hyperpolarized ΔψM is stabilized almost completely by the action of glucose oxidation, whereas proton leak also contributes to the homeostatic control of ΔψM at low glucose. These findings suggest a strong positive feedback loop in the regulation of β-cell energetics, and a possible regulatory role of proton leak in the fasting state. Analysis of islet bioenergetics from published cases of type 2 diabetes suggests that disruption of this feedback can explain the damaged bioenergetic response of β-cells to glucose.

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

    PubMed Central

    McIlwrath, Sabrina L; Westlund, Karin N

    2015-01-01

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

  13. Cellular pathways to beta-cell replacement.

    PubMed

    Fellous, Tariq G; Guppy, Naomi J; Brittan, Mairi; Alison, Malcolm R

    2007-02-01

    In the twenty-first century, diabetic patients are likely to be one of the major beneficiaries from the advancement of regenerative medicine through cellular therapies. Though the existence of a specific self-renewing stem cell within the pancreas is still far from clear, a surprising variety of cells within the pancreas can differentiate towards a beta-cell phenotype: ductular cells, periductular mesenchymal cells and beta-cells themselves can all give rise to new beta-cells. Extra-pancreatic adult somatic stem cells, in particular, those originating from bone marrow may also be capable of differentiating to beta-cells, though equally well the beneficial effects of bone marrow cells may reside in their contribution to the damaged islet vasculature. Forced expression of the beta-cell-specific transcription factor Pdx1 in hepatocytes also holds promise as a therapeutic strategy to increase insulin levels in diabetic individuals. Embryonic stem (ES) cells are clearly another possible source for generating beta-cells, but ES cells are beyond the scope of this review, which focuses on adult stem and progenitor cells capable of producing beta-cells. Despite considerable endeavour, we still have much to learn in the field of pancreatic regeneration prior to any clinically applicable therapy based upon adult stem cells.

  14. Monitoring of exocytosis and endocytosis of insulin secretory granules in the pancreatic beta-cell line MIN6 using pH-sensitive green fluorescent protein (pHluorin) and confocal laser microscopy.

    PubMed

    Ohara-Imaizumi, Mica; Nakamichi, Yoko; Tanaka, Toshiaki; Katsuta, Hidenori; Ishida, Hitoshi; Nagamatsu, Shinya

    2002-04-01

    The dynamics of exocytosis/endocytosis of insulin secretory granules in pancreatic beta-cells remains to be clarified. In the present study, we visualized and analysed the motion of insulin secretory granules in MIN6 cells using pH-sensitive green fluorescent protein (pHluorin) fused to either insulin or the vesicle membrane protein, phogrin. In order to monitor insulin exocytosis, pHluorin, which is brightly fluorescent at approximately pH 7.4, but not at approximately pH 5.0, was attached to the C-terminus of insulin. To monitor the motion of insulin secretory granules throughout exocytosis/endocytosis, pHluorin was inserted between the third and fourth amino acids after the identified signal-peptide cleavage site of rat phogrin cDNA. Using this method of cDNA construction, pHluorin was located in the vesicle lumen, which may enable discrimination of the unfused acidic secretory granules from the fused neutralized ones. In MIN6 cells expressing insulin-pHluorin, time-lapse confocal laser scanning microscopy (5 or 10 s intervals) revealed the appearance of fluorescent spots by depolarization after stimulation with 50 mM KCl and 22 mM glucose. The number of these spots in the image at the indicated times was counted and found to be consistent with the results of insulin release measured by RIA during the time course. In MIN6 cells expressing phogrin-pHluorin, data showed that fluorescent spots appeared following high KCl stimulation and remained stationary for a while, moved on the plasma membrane and then disappeared. Thus we demonstrate the visualized motion of insulin granule exocytosis/endocytosis using the pH-sensitive marker, pHluorin.

  15. Role of ischemia in acute pancreatitis. Hemorrhagic shock converts edematous pancreatitis to hemorrhagic pancreatitis in rats.

    PubMed

    Kyogoku, T; Manabe, T; Tobe, T

    1992-09-01

    Ischemia has been considered to play a role in the development of acute pancreatitis. The aim of this study was to investigate the effect of ischemia, caused by hemorrhagic shock, on cerulein-induced acute pancreatitis in rats. Acute pancreatitis was induced by the intravenous infusion of a supramaximally stimulating dose of cerulein (10 micrograms/kg/hr) for 6 hr. Hemorrhagic shock was induced by the removal of blood until the mean arterial blood pressure reached 35 mm Hg. This level was maintained for 30 min, after which time all the blood was reinfused. Hemorrhagic shock alone induced no morphological change in the pancreas. However, after the induction of hemorrhagic shock in animals treated with cerulein, hemorrhage and parenchymal necrosis were frequently observed in the pancreas. Seven of 20 rats (35%) receiving cerulein plus hemorrhagic shock had died by 48 hr after the start of cerulein infusion, whereas none of the rats in the cerulein or shock group died during this experiment. Cathepsin B activity in the pancreas of the cerulein plus shock group was significantly higher than in the other groups at 48 hr. These results suggest that ischemia may be a contributing factor in the pathogenesis of acute pancreatitis.

  16. Arsenic Exposure and Calpain-10 Polymorphisms Impair the Function of Pancreatic Beta-Cells in Humans: A Pilot Study of Risk Factors for T2DM

    PubMed Central

    Díaz-Villaseñor, Andrea; Cruz, Laura; Cebrián, Arturo; Hernández-Ramírez, Raúl U.; Hiriart, Marcia; García-Vargas, Gonzálo; Bassol, Susana; Sordo, Monserrat; Gandolfi, A. Jay; Klimecki, Walter T.; López-Carillo, Lizbeth; Cebrián, Mariano E.; Ostrosky-Wegman, Patricia

    2013-01-01

    The incidence of type 2 diabetes mellitus (T2DM) is increasing worldwide and diverse environmental and genetic risk factors are well recognized. Single nucleotide polymorphisms (SNPs) in the calpain-10 gene (CAPN-10), which encodes a protein involved in the secretion and action of insulin, and chronic exposure to inorganic arsenic (iAs) through drinking water have been independently associated with an increase in the risk for T2DM. In the present work we evaluated if CAPN-10 SNPs and iAs exposure jointly contribute to the outcome of T2DM. Insulin secretion (beta-cell function) and insulin sensitivity were evaluated indirectly through validated indexes (HOMA2) in subjects with and without T2DM who have been exposed to a gradient of iAs in their drinking water in northern Mexico. The results were analyzed taking into account the presence of the risk factor SNPs SNP-43 and -44 in CAPN-10. Subjects with T2DM had significantly lower beta-cell function and insulin sensitivity. An inverse association was found between beta-cell function and iAs exposure, the association being more pronounced in subjects with T2DM. Subjects without T2DM who were carriers of the at-risk genotype SNP-43 or -44, also had significantly lower beta-cell function. The association of SNP-43 with beta-cell function was dependent on iAs exposure, age, gender and BMI, whereas the association with SNP-44 was independent of all of these factors. Chronic exposure to iAs seems to be a risk factor for T2DM in humans through the reduction of beta-cell function, with an enhanced effect seen in the presence of the at-risk genotype of SNP-43 in CAPN-10. Carriers of CAPN-10 SNP-44 have also shown reduced beta-cell function. PMID:23349674

  17. Reprogramming of human exocrine pancreas cells to beta cells.

    PubMed

    Staels, Willem; Heremans, Yves; Heimberg, Harry

    2015-12-01

    One of the key promises of regenerative medicine is providing a cure for diabetes. Cell-based therapies are proving their safety and efficiency, but donor beta cell shortages and immunological issues remain major hurdles. Reprogramming of human pancreatic exocrine cells towards beta cells would offer a major advantage by providing an abundant and autologous source of beta cells. Over the past decade our understanding of transdifferentiation processes greatly increased allowing us to design reprogramming protocols that fairly aim for clinical trials.

  18. Activation of the Nlrp3 inflammasome in infiltrating macrophages by endocannabinoids mediates beta cell loss in type 2 diabetes.

    PubMed

    Jourdan, Tony; Godlewski, Grzegorz; Cinar, Resat; Bertola, Adeline; Szanda, Gergő; Liu, Jie; Tam, Joseph; Han, Tiffany; Mukhopadhyay, Bani; Skarulis, Monica C; Ju, Cynthia; Aouadi, Myriam; Czech, Michael P; Kunos, George

    2013-09-01

    Type 2 diabetes mellitus (T2DM) progresses from compensated insulin resistance to beta cell failure resulting in uncompensated hyperglycemia, a process replicated in the Zucker diabetic fatty (ZDF) rat. The Nlrp3 inflammasome has been implicated in obesity-induced insulin resistance and beta cell failure. Endocannabinoids contribute to insulin resistance through activation of peripheral CB1 receptors (CB₁Rs) and also promote beta cell failure. Here we show that beta cell failure in adult ZDF rats is not associated with CB₁R signaling in beta cells, but rather in M1 macrophages infiltrating into pancreatic islets, and that this leads to activation of the Nlrp3-ASC inflammasome in the macrophages. These effects are replicated in vitro by incubating wild-type human or rodent macrophages, but not macrophages from CB₁R-deficient (Cnr1(-/-)) or Nlrp3(-/-) mice, with the endocannabinoid anandamide. Peripheral CB₁R blockade, in vivo depletion of macrophages or macrophage-specific knockdown of CB₁R reverses or prevents these changes and restores normoglycemia and glucose-induced insulin secretion. These findings implicate endocannabinoids and inflammasome activation in beta cell failure and identify macrophage-expressed CB₁R as a therapeutic target in T2DM.

  19. Role of fibrosis-related genes and pancreatic duct obstruction in rat pancreatitis models: implications for chronic pancreatitis.

    PubMed

    Miyauchi, M; Suda, K; Kuwayama, C; Abe, H; Kakinuma, C

    2007-10-01

    Human chronic pancreatitis is characterized by irreversible fibrosis, whereas pancreatic fibrosis in animal models is reversible. In this study, we compare the development of pancreatic fibrosis in the dibutyltin dichloride (DBTC) model, WBN/Kob rats and bile duct-ligated (BDL) rats. DBTC (8 mg/kg) was administered to LEW rats, and the pancreas was histopathologically investigated sequentially. Male and female WBN/Kob rats aged 4, 6 and 8 months were also examined. BDL rats were prepared by ligation of the bile duct at the duodenal portion and sacrificed at 3 or 7 days after ligation. Fibrosis in the DBTC model peaked after 1 week and was limited to the areas around the pancreatic ducts after 2 weeks, and was composed of both type I and type III collagen. In contrast, fibrosis in male WBN/Kob rats peaked at age 4 months, expanded into intralobular area, and was composed of type III collagen. It exhibited almost no type I collagen and a marked tendency to regress. Pancreatic fibrosis in BDL rats was somewhat difficult to induce and required increased stimulation. This suggests that fibrosis in human biliary pancreatitis may gradually form based on weak, continuous stimulation. We conclude that type I collagen may be involved in the progression of irreversible fibrosis. The imbalance between synthesis and degradation of extracellular matrix molecules or degree of stimulation over a certain period may lead to pancreatic fibrosis. Gene expressions of prolyl hydroxylase and tissue inhibitors of matrix metalloproteinase-2 were elevated.

  20. Differential effect of sulfonylureas on production of reactive oxygen species and apoptosis in cultured pancreatic beta-cell line, MIN6.

    PubMed

    Sawada, Fumi; Inoguchi, Toyoshi; Tsubouchi, Hirotaka; Sasaki, Shuji; Fujii, Masakazu; Maeda, Yasutaka; Morinaga, Hidetaka; Nomura, Masatoshi; Kobayashi, Kunihisa; Takayanagi, Ryoichi

    2008-08-01

    Sulfonylureas are considered to cause beta-cell apoptosis. However, it is unclear how this occurs and whether there is a difference in such effects among various sulfonylureas. Here, we examined the effects of various sulfonylureas and a short-acting insulin secretagogue, nateglinide, on oxidative stress and apoptosis using the beta-cell line MIN6. After cultured MIN6 cells were exposed to various concentrations of sulfonylureas (glibenclamide, glimepiride, and gliclazide) or nateglinide, intracellular production of reactive oxygen species (ROS) was evaluated by staining with 2',7'-dichlorofluorescein diacetate. The effect of these agents on apoptosis was also evaluated by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling technique. Exposure of beta-cells to glibenclamide, glimepiride, and nateglinide significantly increased intracellular ROS production in a concentration-dependent manner (0.1-10 micromol/L). These effects were completely blocked by nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase inhibitors (diphenylene iodonium or apocynin) or a protein kinase C inhibitor (calphostin C). After exposure to these agents for 48 hours, the numbers of apoptotic cells were also significantly increased. These effects were significantly blocked by apocynin and antioxidant N-acetyl-L-cysteine. In contrast, exposure to any concentrations of gliclazide did not affect either intracellular ROS production or the numbers of apoptotic cells. Sulfonylureas (glibenclamide and glimepiride, but not gliclazide) and nateglinide stimulated ROS production via protein kinase C-dependent activation of NAD(P)H oxidase and consequently caused beta-cell apoptosis in vitro. Because of the lack of such adverse effects, gliclazide may have a benefit in the preservation of functional beta-cell mass.

  1. Fasting prevents acute pancreatitis induced by cerulein in rats.

    PubMed

    Otsuki, M; Tani, S; Okabayashi, Y; Fujii, M; Nakamura, T; Fujisawa, T; Koide, M; Itoh, H

    1990-07-01

    We examined the effect of fasting on the course of experimental acute pancreatitis induced in rats by four subcutaneous injections of 20 micrograms/kg body weight of cerulein at hourly intervals. Rats were either fasted from 24 hr before to 9 hr after the first cerulein injection or fed ad libitum throughout the experiment. Twenty-four hours of fasting reduced cerulein-induced increases in serum levels of amylase and anionic trypsin(ogen) to 50 and 70% of those in fed rats, respectively. Increases in pancreatic wet weight after cerulein injections were also less in fasted rats than in fed rats. Pancreatic content of trypsin was significantly decreased after a 24-hr fast, and no further changes were induced by cerulein injections. The histological signs of acute pancreatitis were greatly alleviated by fasting. However, 24 hr of fasting did not alter the sensitivity and responsiveness of the exocrine pancreas to cerulein in both in vivo and in vitro. Plasma CCK bioactivity and immunoreactive secretin concentration in 24-hr-fasted rats were significantly lower than those in fed rats. Administration of CCK receptor antagonist, loxiglumide, 12 hr prior to the induction of acute pancreatitis reduced the increase in serum amylase activity in fed rats to nearly the same levels as that in fasted rats and alleviated histological signs of pancreatitis to some extent. These present observations suggest that fasting lessens the severity of cerulein-induced acute pancreatitis by reducing endogenous CCK release.

  2. Hepatocyte growth factor attenuates pancreatic damage in caerulein-induced pancreatitis in rats.

    PubMed

    Warzecha, Z; Dembiński, A; Konturek, P C; Ceranowicz, P; Konturek, S J; Tomaszewska, R; Schuppan, D; Stachura, J; Nakamura, T

    2001-10-26

    Hepatocyte growth factor (HGF) overexpression was reported in experimental and clinical acute pancreatitis. These observations prompted us to determine the effect of HGF administration on the development of caerulein-induced pancreatitis in rats. Acute pancreatitis was induced by s.c. infusion of caerulein (10 microg/kg/h) for 5 h. HGF was administrated twice (30 min before caerulein or saline infusion and 3 h later) at the doses: 0.4, 2, 10 or 50 microg/kg s.c. Immediately after cessation of caerulein or saline infusion, the pancreatic blood flow, plasma amylase and lipase activity, plasma cytokines concentration, cell proliferation, and morphological signs of pancreatitis were examined. Caerulein administration induced acute edematous pancreatitis manifested by 41% decrease in DNA synthesis, 53% inhibition of pancreatic blood flow, a significant increase in plasma amylase and lipase activity, plasma interleukin-1beta and interleukin-6 concentration, as well as, the development of the histological signs of pancreatic damage (edema, leukocyte infiltration, and vacuolization). Administration of HGF without induction of pancreatitis increased plasma interleukin-10. Treatment with HGF, during induction of pancreatitis, increased plasma interleukin-10 and attenuated the pancreatic damage, what was manifested by histological improvement of pancreatic integrity, the partial reversion of the drop in DNA synthesis and pancreatic blood flow, and the reduction in pancreatitis evoked increase in plasma amylase, lipase, and interleukin-1beta and interleukin-6 levels. HGF administrated at the dose 2 microg/kg exhibited a similar beneficial effect as administration of HGF at the doses 10 or 50 microg/kg. Treatment with HGF at the dose 0.4 microg/kg was less effective. We conclude that: (1) administration of HGF attenuates pancreatic damage in caerulein-induced pancreatitis; (2) this effect seems to be related to the increase in production of interleukin-10, the reduction in

  3. Cyproheptadine metabolites inhibit proinsulin and insulin biosynthesis and insulin release in isolated rat pancreatic islets

    SciTech Connect

    Chow, S.A.; Falany, J.L.; Fischer, L.J. )

    1989-06-01

    The contribution of drug metabolites to cyproheptadine (CPH)-induced alterations in endocrine pancreatic beta-cells was investigated by examining the inhibitory activity of CPH and its biotransformation products, desmethylcyproheptadine (DMCPH), CPH-epoxide and DMCPH-epoxide, on hormone biosynthesis and secretion in pancreatic islets isolated from 50-day-old rats. Measurement of (pro)insulin (proinsulin and insulin) synthesis using incorporation of 3H-leucine showed that DMCPH-epoxide, DMCPH and CPH-epoxide were 22, 10 and 4 times, respectively, more potent than CPH in inhibiting hormone synthesis. The biosynthesis of (pro)insulin was also inhibited by CPH and DMCPH-epoxide in islets isolated from 21-day-old rat fetuses. The inhibitory action of CPH and its metabolites was apparently specific for (pro)insulin, and the synthesis of other islet proteins was not affected. Other experiments showed the metabolites of CPH were active in inhibiting glucose-stimulated insulin secretion but were less potent than the parent drug in producing this effect. CPH and its structurally related metabolites, therefore, have differential inhibitory activities on insulin synthesis and release. The observation that CPH metabolites have higher potency than CPH to inhibit (pro)insulin synthesis, when considered with published reports on the disposition of the drug in rats, indicate that CPH metabolites, particularly DMCPH-epoxide, are primarily responsible for the insulin depletion observed when the parent compound is given to fetal and adult animals.

  4. The acquisition of an insulin-secreting phenotype by HGF-treated rat pancreatic ductal cells (ARIP) is associated with the development of susceptibility to cytokine-induced apoptosis.

    PubMed

    Anastasi, E; Santangelo, C; Bulotta, A; Dotta, F; Argenti, B; Mincione, C; Gulino, A; Maroder, M; Perfetti, R; Di Mario, U

    2005-04-01

    The elucidation of mechanisms regulating the regeneration and survival of pancreatic beta cells has fundamental implications in the cell therapy of type 1 diabetes. The present study had the following three aims: 1. to investigate whether pancreatic ductal epithelial cells can be induced to differentiate into insulin-producing cells by exposing them to hepatocyte growth factor (HGF); 2. to characterize some of the molecular events leading to their differentiation toward a beta-cell-like phenotype; 3. to evaluate the susceptibility of newly differentiated insulin-secreting cells to cytokine-induced apoptosis, a mechanism of beta-cell destruction occurring in type 1 diabetes. We demonstrated that HGF-treated rat pancreatic ductal cell line (ARIP) cells acquired the capability to transcribe the insulin gene and translate its counterpart protein. HGF-treated cells also exhibited a glucose-dependent capability to secrete insulin into the cultured medium. Expression analysis of some of the genes regulating pancreatic beta-cell differentiation revealed a time-dependent transcription of neurogenin-3 and Neuro-D in response to HGF. Finally, we determined the susceptibility to proinflammatory cytokine (PTh1)-induced apoptosis by incubating HGF-treated and untreated ARIP cells with a cocktail of interleukin-1 beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). Such treatment induced apoptotic death, as determined by the TUNEL technique, in about 40% of HGF-treated, insulin-secreting ARIP cells, while untreated ARIP cells were resistant to PTh1-induced apoptosis. In conclusion, we showed that HGF promotes the differentiation of ARIP cells into pancreatic beta-cell-like cells, and that the differentiation toward an insulin-secreting phenotype is associated with the appearance of susceptibility to cytokine-induced apoptosis.

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

    SciTech Connect

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

    1990-12-01

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

  6. Sonic hedgehog expression in a rat model of chronic pancreatitis

    PubMed Central

    Wang, Luo-Wei; Lin, Han; Lu, Yi; Xia, Wei; Gao, Jun; Li, Zhao-Shen

    2014-01-01

    AIM: To analyze the activation of sonic hedgehog (SHh) signaling pathways in a rat model of chronic pancreatitis. METHODS: Forty Wistar rats were randomly divided into 2 groups: experimental group and control group (20 rats in each group). Dibutyltin dichloride was infused into the tail vein of the rats to induce chronic pancreatitis in the experimental group. The same volume of ethanol and glycerol mixture was infused in the control group. The expression of Ptch, Smo and Gli were analyzed using immunohistochemistry, and real-time reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Compared with the control group, significant histological changes in terms of the areas of abnormal architecture, glandular atrophy, fibrosis, pseudo tubular complexes, and edema were observed at week 4 in the experimental group. The expression of Ptch1, Smo and Gli1 in the pancreatic tissue increased significantly in the experimental group. Using RT-PCR, mRNA levels of Ptch, Smo and Gli in the experimental group increased significantly compared with the control group. CONCLUSION: The SHh signaling pathway is aberrantly activated in rats with chronic pancreatitis. The SHh signaling pathway plays an important role in the development of chronic pancreatitis. These results may be helpful in studies focusing on the relationship between chronic pancreatitis and pancreatic cancer. PMID:24782623

  7. Endotoxemia in newborn rats attenuates acute pancreatitis at adult age.

    PubMed

    Jaworek, J; Konturek, S J; Macko, M; Kot, M; Szklarczyk, J; Leja-Szpak, A; Nawrot-Porabka, K; Stachura, J; Tomaszewska, R; Siwicki, A; Pawlik, W W

    2007-03-01

    Bacterial endotoxin (lipopolysaccharide, LPS), at high concentration is responsible for sepsis, and neonatal mortality, however low concentration of LPS protected the pancreas against acute damage. The aim of this study was to investigate the effect of exposition of suckling rats to LPS on the course of acute pancreatitis at adult age. Suckling rat (30-40g) received intraperitoneal (i.p.) injection of saline (control) or LPS from Escherichia coli or Salmonella typhi (5, 10 or 15 mg/kg-day) during 5 consecutive days. Two months later these rats have been subjected to i.p. cearulein infusion (25 microg/kg) to produce caerulein-induced pancreatitis (CIP). The following parameters were tested: pancreatic weight and morphology, plasma amylase and lipase activities, interleukin 1beta (IL-1 beta), interleukin 6 (IL-6), and interleukin 10 (IL-10) plasma concentrations. Pancreatic concentration of superoxide dismutase (SOD) and lipid peroxidation products; malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) have been also measured. Caerulein infusion produced CIP in all animals tested, that was confirmed by histological examination. In the rats, which have been subjected in the neonatal period of life to LPS at doses 10 or 15 mg/kg-day x 5 days, all manifestations of CIP have been reduced. In these animals acute inflammatory infiltration of pancreatic tissue and pancreatic cell vacuolization have been significantly diminished. Also pancreatic weight, plasma lipase and alpha-amylase activities, as well as plasma concentrations of IL-1beta and IL-6 have been markedly decreased, whereas plasma anti-inflammatory IL-10 concentration was significantly increased in these animals as compared to the control rats, subjected in the infancy to saline injection instead of LPS. Caerulein-induced fall in pancreatic SOD concentration was reversed and accompanied by significant reduction of MDA + 4 HNE in the pancreatic tissue. The effects of LPS derived from E. coli or S. typhi were similar

  8. Gene and protein kinase expression profiling of reactive oxygen species-associated lipotoxicity in the pancreatic beta-cell line MIN6.

    PubMed

    Wang, Xiaolin; Li, Hui; De Leo, Domenica; Guo, Wanbei; Koshkin, Vasilij; Fantus, I George; Giacca, Adria; Chan, Catherine B; Der, Sandy; Wheeler, Michael B

    2004-01-01

    Oligonucleotide microarrays were used to define oleic acid (OA)-regulated gene expression and proteomic technology to screen protein kinases in MIN6 insulinoma cells. The effects of oxidative stress caused by OA and potential protective effects of N-acetyl-L-cysteine (NAC), a scavenger of reactive oxygen species (ROS), on global gene expression and beta-cell function were investigated. Long-term exposure of MIN6 cells to OA led to a threefold increase in basal insulin secretion, a 50% decrease in insulin content, an inhibition of glucose-stimulated insulin secretion (GSIS), and a twofold increase in the level of ROS. The addition of NAC normalized both the OA-induced insulin content and ROS elevation, but it failed to restore GSIS. Microarray studies and subsequent quantitative PCR analysis showed that OA consistently regulated the expression of 45 genes involved in metabolism, cell growth, signal transduction, transcription, and protein processing. The addition of NAC largely normalized the expression of the OA-regulated genes involved in cell growth and differentiation but not other functions. A protein kinase screen showed that OA regulated the expression and/or phosphorylation levels of kinases involved in stress-response mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and cell cycle control pathways. Importantly, these findings indicate that chronic OA exposure can impair beta-cell function through ROS-dependent and -independent mechanisms.

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

    PubMed

    Singh, Neera; Gupta, Manushma

    2007-12-01

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

  10. Inhibition of pancreatic protein secretion by ghrelin in the rat

    PubMed Central

    Zhang, Weizhen; Chen, Min; Chen, Xuequn; Segura, Bradley J; Mulholland, Michael W

    2001-01-01

    The role of ghrelin in the regulation of pancreatic protein secretion was investigated in vivo using anaesthetized rats with pancreatic ductal cannulas, and in isolated pancreatic acinar cells and pancreatic lobules in vitro. In vivo, pancreatic protein output stimulated by CCK-8 (400 pmol kg−1 h−1) was dose-dependently inhibited by continuous ghrelin infusion (1.2 and 12 nmol kg−1 h−1) by 45 ± 8 and 84 ± 7 %, respectively. In rats with acute subdiaphragmatic vagotomy, ghrelin (12 nmol kg−1 h−1) significantly inhibited CCK-stimulated pancreatic protein secretion by 75 ± 18 %. Infusion of ghrelin (12 nmol kg−1 h−1) abolished pancreatic protein secretion caused by the central vagal stimulant 2-deoxy-d-glucose (75 mg kg−1), whereas bethanechol-stimulated pancreatic protein output was inhibited by only 59 ± 7 %. In vitro, ghrelin (10−11–10−7m) produced no change in basal amylase release from dispersed, purified acinar cells. Co-incubation of ghrelin (10−11−10−7m) with CCK−8 (10−10m) demonstrated no inhibition of CCK-stimulated amylase release from dispersed acini. In contrast, ghrelin (10−9−10−7m) dose-dependently inhibited amylase release from pancreatic lobules exposed to 75 mm potassium. Our results show that (1) ghrelin is a potent inhibitor of pancreatic exocrine secretion in anaesthetized rats in vivo and in pancreatic lobules in vitro; and (2) the actions of ghrelin are indirect and may be exerted at the level of intrapancreatic neurons. PMID:11711576

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

    SciTech Connect

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

    2012-09-21

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

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

    PubMed

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

    2002-07-05

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

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  14. Development and application of a self-referencing glucose microsensor for the measurement of glucose consumption by pancreatic beta-cells.

    PubMed

    Jung, S K; Trimarchi, J R; Sanger, R H; Smith, P J

    2001-08-01

    Glucose gradients generated by an artificial source and beta-cells were measured using an enzyme-based glucose microsensor, 8-microm tip diameter, as a self-referencing electrode. The technique is based on a difference measurement between two locations in a gradient and thus allows us to obtain real-time flux values with minimal impact of sensor drift or noise. Flux values were derived by incorporation of the measured differential current into Fick's first equation. In an artificial glucose gradient, a flux detection limit of 8.2 +/- 0.4 pmol.cm(-2).s(-1) (mean +/- SEM, n = 7) with a sensor sensitivity of 7.0 +/- 0.4 pA/ mM (mean +/- SEM, n = 16) was demonstrated. Under biological conditions, the glucose sensor showed no oxygen dependence with 5 mM glucose in the bulk medium. The addition of catalase to the bulk medium was shown to ameliorate surface-dependent flux distortion close to specimens, suggesting an underlying local accumulation of hydrogen peroxide. Glucose flux from beta-cell clusters, measured in the presence of 5 mM glucose, was 61.7 +/- 9.5 fmol.nL(-1).s(-1) (mean +/- SEM, n = 9) and could be pharmacologically modulated. Glucose consumption in response to FCCP (1 microM) transiently increased, subsequently decreasing to below basal by 93 +/- 16 and 56 +/- 6%, respectively (mean +/- SEM, n = 5). Consumption was decreased after the application of 10 microM rotenone by 74 +/- 5% (mean +/- SEM, n = 4). These results demonstrate that an enzyme-based amperometric microsensor can be applied in the self-referencing mode. Further, in obtaining glucose flux measurements from small clusters of cells, these are the first recordings of the real-time dynamic of glucose movements in a biological microenvironment.

  15. Heat shock protein induction in rat pancreatic islets by recombinant human interleukin 1 beta.

    PubMed

    Helqvist, S; Polla, B S; Johannesen, J; Nerup, J

    1991-03-01

    Interleukin 1 beta, potentiated by tumour necrosis factor alpha, is cytotoxic to pancreatic Beta cells in vitro. We have hypothesized that interleukin 1 beta induces oxygen free radicals in Beta cells. Since cytotoxicity induced by free radicals and by heat may activate the same cellular repair mechanism (the heat shock response), the aim of this study was to investigate the pattern of protein synthesis in isolated islets after exposure to interleukin 1 beta (150 pg/ml, 24 h), tumour necrosis factor alpha (50 ng/ml, 24 h) heat shock (43 degrees C, 30 min) and H2O2 (0.1 mmol/l, 20 min). By polyacrylamide gel electrophoresis, autoradiography, Western-blot analysis and partial peptide mapping of 35S-methionine labelled islets, interleukin 1 beta was found to induce a 73 kilodalton protein belonging to the heat shock protein family heat shock protein 70, a heat shock protein 90, and haem oxygenase. A minor induction of heat shock protein 73 and haem oxygenase was seen after H2O2. Interleukin 1 beta did not induce heat shock proteins in rat thyroid cells, rat mesangial cells or in human monocytes. Tumour necrosis factor alpha did not induce selective protein synthesis. Pre-exposure of islets to heat, tumour necrosis factor alpha, or H2O2 did not prevent the impairment of glucose-stimulated insulin release seen after 24 h of interleukin 1 beta exposure. The data are compatible with free radical induction by interleukin 1 beta. However, the heat shock response is not specific for oxidative injury, and previous studies have shown discrepant effects as to a protective effect of free radical scavengers against interleukin 1 beta-mediated beta-cytotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Effect of emodin on pancreatic fibrosis in rats

    PubMed Central

    Wang, Cai-Hua; Gao, Zhi-Qiang; Ye, Bing; Cai, Jian-Ting; Xie, Chuan-Gao; Qian, Ke-Da; Du, Qin

    2007-01-01

    AIM: To establish the rats model of chronic fibrosing pancreatitis and to prove the anti-fibrotic effect of emodin in chronic pancreatitis with fibrosis. METHODS: Fifty rats were randomly divided into five groups, 10 rats in each group. Trinitrobenzene sulfonic acid (TNBS) was infused into the pancreatic duct to induce chronic pancreatitis in rats (except for normal group). Emodin-treated rats were fed with different doses of emodin (20, 40 and 80 mg/kg body weight) for 28 d, while normal group and control group received 0.9% sodium chloride solution. Serum levels of hyaluronic acid (HA) and laminin (LN) were determined by radioimmunoassay. Histopathological alterations were studied by optical microscopy. Expression of collagen was also examined while transforming growth factor-beta-1 (TGF-β1) was localized by immunochemistry. RESULTS: In emodin-treated rats, the serum levels of HA and LN were decreased significantly (HA, 62.2 ± 19.3 μg/L vs 112.7 ± 26.5 µg/L, P < 0.05; LN 44.3 ± 10.4 μg/L vs 86.2 ± 16.5 µg/L, P < 0.05); the degree of fibrosis was ameliorated observably; the expression of collagen in pancreatic tissue was reduced especially in high-dose emodin-treated group (36% ± 5% vs 42% ± 6%, P < 0.05); with the increased doses of emodin, the expression of TGF-β1 was declined, compared with those in control group. CONCLUSION: Emodin has an anti-fibrotic effect on pancreatic fibrosis in rats. Because of its anti-fibrotic effect, it could be a potential herb for the treatment of chronic pancreatitis. PMID:17230605

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

    PubMed

    Khan, S; Jena, G B

    2014-04-25

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

  18. Danaparoid sodium prevents cerulein-induced acute pancreatitis in rats.

    PubMed

    Hagiwara, Satoshi; Iwasaka, Hideo; Uchida, Tomohisa; Hasegawa, Akira; Asai, Nobuhiko; Noguchi, Takayuki

    2009-07-01

    Systemic inflammatory mediators, including the protein high-mobility group box 1 (HMGB1), play an important role in the development of acute pancreatitis. Anticoagulants such as danaparoid sodium (DA) may be able to inhibit sepsis-induced inflammation, but the mechanism of action is not well understood. We hypothesized that DA would act as an inhibitor of inflammation and prevent cerulein-induced acute pancreatitis. Male Wistar rats were used as subjects in this study. Each received a bolus of 50 U/kg of DA or saline-injected into the tail vein, followed by 4 injections of 50 mg/kg cerulean (i.p.) at 1-h intervals. Cytokine (IL-6), NO, and HMGB1 levels in serum and pancreatic tissue were measured after the cerulein injection. Pancreas histopathology and wet-dry ratio significantly improved in the DA-injected (50 U/kg) animals compared with saline-injected rats. Serum and pancreatic HMGB1 levels decreased over time in DA-treated animals. Danaparoid sodium also decreased cytokine, NO, and HMGB1 levels during cerulein-induced inflammation. As a result, DA ameliorated pancreas pathology in the rat model of cerulein-induced acute pancreatitis. This study demonstrates that DA treatment prevents cerulein-induced acute pancreatitis in a rat model. This effect may be mediated through inhibition of cytokines, NO, and HMGB1.

  19. Intracellular-produced hydroxyl radical mediates H2O2-induced Ca2+ influx and cell death in rat beta-cell line RIN-5F.

    PubMed

    Ishii, Masakazu; Shimizu, Shunichi; Hara, Yuji; Hagiwara, Tamio; Miyazaki, Akira; Mori, Yasuo; Kiuchi, Yuji

    2006-06-01

    The melastatin-related transient receptor potential channel TRPM2 is a Ca(2+)-permeable channel that is activated by H(2)O(2), and the Ca(2+) influx through TRPM2 mediates cell death. However, the responsible oxidants for TRPM2 activation remain to be identified. In the present study, we investigated the involvement of hydroxyl radical on TRPM2 activation in TRPM2-expressing HEK293 cells and the rat beta-cell line RIN-5F. In both cell types, H(2)O(2) induced Ca(2+) influx in a concentration-dependent manner. However, the addition of hydroxyl radical, which was produced by mixing FeSO(4) and H(2)O(2), to the cells, did not increase intracellular Ca(2+) concentration. Interestingly, when H(2)O(2) was added to the cells under intracellular Fe(2+)-accumulated conditions, Ca(2+) influx was markedly enhanced compared to H(2)O(2) alone. In addition, the H(2)O(2)-induced Ca(2+) influx was reduced by hydroxyl radical scavengers and an iron chelator. Under intracellular Fe(2+)-accumulated conditions, H(2)O(2)-induced RIN-5F cell death through TRPM2 activation was also markedly enhanced. Hydroxyl radical scavengers and an iron chelator suppressed the RIN-5F cell death by H(2)O(2). These results strongly suggest that the intracellular hydroxyl radical plays a key role in the activation of TRPM2 during H(2)O(2) treatment, and TRPM2 activation mediated by hydroxyl radical is implicated in H(2)O(2)-induced cell death in the beta-cell line RIN-5F.

  20. Proteasome Dysfunction Mediates High Glucose-Induced Apoptosis in Rodent Beta Cells and Human Islets

    PubMed Central

    Broca, Christophe; Varin, Elodie; Armanet, Mathieu; Tourrel-Cuzin, Cécile; Bosco, Domenico; Dalle, Stéphane; Wojtusciszyn, Anne

    2014-01-01

    The ubiquitin/proteasome system (UPS), a major cellular protein degradation machinery, plays key roles in the regulation of many cell functions. Glucotoxicity mediated by chronic hyperglycaemia is detrimental to the function and survival of pancreatic beta cells. The aim of our study was to determine whether proteasome dysfunction could be involved in beta cell apoptosis in glucotoxic conditions, and to evaluate whether such a dysfunction might be pharmacologically corrected. Therefore, UPS activity was measured in GK rats islets, INS-1E beta cells or human islets after high glucose and/or UPS inhibitor exposure. Immunoblotting was used to quantify polyubiquitinated proteins, endoplasmic reticulum (ER) stress through CHOP expression, and apoptosis through the cleavage of PARP and caspase-3, whereas total cell death was detected through histone-associated DNA fragments measurement. In vitro, we found that chronic exposure of INS-1E cells to high glucose concentrations significantly decreases the three proteasome activities by 20% and leads to caspase-3-dependent apoptosis. We showed that pharmacological blockade of UPS activity by 20% leads to apoptosis in a same way. Indeed, ER stress was involved in both conditions. These results were confirmed in human islets, and proteasome activities were also decreased in hyperglycemic GK rats islets. Moreover, we observed that a high glucose treatment hypersensitized beta cells to the apoptotic effect of proteasome inhibitors. Noteworthily, the decreased proteasome activity can be corrected with Exendin-4, which also protected against glucotoxicity-induced apoptosis. Taken together, our findings reveal an important role of proteasome activity in high glucose-induced beta cell apoptosis, potentially linking ER stress and glucotoxicity. These proteasome dysfunctions can be reversed by a GLP-1 analog. Thus, UPS may be a potent target to treat deleterious metabolic conditions leading to type 2 diabetes. PMID:24642635

  1. Genome-wide identification of palmitate-regulated immediate early genes and target genes in pancreatic beta-cells reveals a central role of NF-κB.

    PubMed

    Choi, Hyung Jin; Hwang, Seungwoo; Lee, Se-Hee; Lee, You Ri; Shin, Jiyon; Park, Kyong Soo; Cho, Young Min

    2012-06-01

    Free fatty acid-induced pancreatic β-cell dysfunction plays a key role in the pathogenesis of type 2 diabetes. We conducted gene expression microarray analysis to comprehensively investigate the transcription machinery of palmitate-regulated genes in pancreatic β-cells in vitro. In particular, mouse pancreatic βTC3 cells were treated with palmitate in the presence or absence of cycloheximide (CHX), which blocks protein synthesis and thereby allows us to distinguish immediate early genes (IEGs) from their target genes. The microarray experiments identified 34 palmitate-regulated IEGs and 74 palmitate-regulated target genes. In silico promoter analysis revealed that transcription factor binding sites for NF-κB were over-represented, regulating approximately one-third of the palmitate-regulated target genes. In cells treated with CHX, nfkb1 showed an up-regulation by palmitate, suggesting that NF-κB could be an IEG. Functional enrichment analysis of 27 palmitate-regulated genes with NF-κB binding sites showed an over-representation of genes involved in immune response, inflammatory response, defense response, taxis, regulation of cell proliferation, and regulation of cell death pathways. Electrophoretic mobility shift assay showed that palmitate stimulates NF-κB activity both in the presence and absence of CHX. In conclusion, by identifying IEGs and target genes, the present study depicted a comprehensive view of transcription machinery underlying palmitate-induced inflammation and cell proliferation/death in pancreatic β-cells and our data demonstrated the central role of NF-κB.

  2. Potential role of oral thiazolidinedione therapy in preserving beta-cell function in type 2 diabetes mellitus.

    PubMed

    Walter, Helmut; Lübben, Georg

    2005-01-01

    Worsening glycaemic control in type 2 diabetes mellitus relates to a decline in beta-cell function, associated with impaired negative feedback regulation of insulin release. Insulin resistance, the 'traditional' cornerstone defect of type 2 diabetes, leads to an array of adverse effects on beta cells, including hypertrophy, apoptosis and those caused by lipotoxicity and glucotoxicity. In particular, increased levels of free fatty acids and their metabolites are thought to diminish both insulin synthesis and glucose-stimulated insulin secretion. Thiazolidinediones are synthetic peroxisome proliferator-activated receptor-gamma agonists that decrease insulin resistance but, as in vitro and in vivo studies suggest, may have direct beneficial effects on pancreatic beta cells. Troglitazone, for example, demonstrated improvements in insulin secretory capacity in isolated pancreatic islets from Wistar rats and a hamster beta-cell line. In vivo studies reveal thiazolidinediones promote beta-cell survival and regranulation as well as maintenance of beta-cell mass and reduction in amyloid deposition. Clinical evidence for thiazolidinediones is largely derived from comparative trials, mainly against sulfonylureas and metformin. Data at 2 years from a number of trials are now available and establish the positive effects of thiazolidinediones on glycaemic control. Empirical evidence showing decreases in fasting plasma insulin levels with pioglitazone and rosiglitazone indicate thiazolidinediones also improve insulin sensitivity. A possible effect of thiazolidinediones on normalising asynchronous insulin secretion, as assessed in a short-term placebo-controlled study, is less established. However, recent and ongoing clinical studies are focusing attention on verifying animal and other data, which support the notion that thiazolidinediones have beneficial effects on beta-cell function. These clinical studies have shown thiazolidinediones capable of preventing or delaying the

  3. Protective effects of endothelin-1 on acute pancreatitis in rats.

    PubMed

    Kogire, M; Inoue, K; Higashide, S; Takaori, K; Echigo, Y; Gu, Y J; Sumi, S; Uchida, K; Imamura, M

    1995-06-01

    Endothelin-1, a 21-residue peptide isolated from vascular endothelial cells, has a broad spectrum of actions. To clarify the involvement of endothelin-1 in acute pancreatitis, we examined the effects of endothelin-1 and its receptor antagonist BQ-123 on cerulein-induced pancreatitis in rats. Rats were infused intravenously with heparin-saline (control), endothelin-1 (100 pmol/kg/hr), cerulein (5 micrograms/kg/hr), or cerulein plus endothelin-1 for 3.5 hr. In another experiment, cerulein or cerulein plus BQ-123 (3 mg/kg/hr) was infused. Infusion of cerulein caused hyperamylasemia and pancreatic edema. Endothelin-1, when infused with cerulein, decreased the extent of pancreatic edema with a significant increase in the pancreatic dry- to wet-weight ratio. Histological changes induced by cerulein were markedly attenuated when endothelin-1 was given with cerulein. In contrast, endothelin-receptor blockade with BQ-123 further augmented pancreatic edema caused by cerulein. The extent of inflammatory cell infiltration was greater than BQ-123 was given with cerulein. Endothelin-1 or BQ-123 had no influence on hyperamylasemia. This study suggests that endothelin-1 has protective effects on experimental acute pancreatitis.

  4. Induction of chronic pancreatic disease by trinitrobenzene sulfonic acid infusion into rat pancreatic ducts.

    PubMed

    Puig-Diví, V; Molero, X; Salas, A; Guarner, F; Guarner, L; Malagelada, J R

    1996-11-01

    Despite being a common disease in humans, little is known about the etiopathogenesis of and effective therapeutic approaches to chronic pancreatitis, due mainly to the fact that few simple animal models suitable to study inflammatory and fibrogenetic processes have been described in the pancreas. Trinitrobenzene sulfonic acid (TNBS) induces chronic colitis and cholangitis in the rat. We hypothesized that TNBS instillation into the pancreatic ducts could also result in the development of a chronic pancreatic disease. The biliopancreatic duct of rats was cannulated and tied close to the liver. TNBS [0.4 ml of 2% TNBS in phosphate-buffered saline (PBS)-10% ethanol, pH 8] was infused into the pancreas under a continuous controlled-pressure system. Control rats underwent the same procedure using vehicle only. Pathology assessment of TNBS-treated rats examined at 48 h was consistent with severe acute necrotizing pancreatitis, having a morality rate of 31% and serum amylase activity of 37.4 +/- 8.8 U/ml at 24 h and 13.3 +/- 1.7 U/ml at 48 h (p < 0.01 for both time points compared to PBS/ethanol-treated rats). Groups of 10 rats each were killed at 3, 4, and 6 week after the surgical procedure. Morphological examination revealed changes mimicking features of chronic pancreatitis in humans in 80% (32 of 40) of TNBS-treated rats, consisting in various degrees of periductal and lobular fibrosis, duct stenosis, patchy acute and chronic inflammatory cell infiltrates, and signs of gland atrophy. Animals developing chronic disease had a weight gain rate significantly lower than that of control rats. Serum amylase, fasting glucose, and a glucose tolerance test were not different in diseased or control rats. In conclusion, we were able to induce chronic fibrogenetic inflammatory disease in the pancreas after a single pulse instillation of TNBS into the pancreatic ducts. This might be a useful animal model to study the pathophysiology of inflammatory, fibrogenetic, and reparative

  5. EFFECT OF PANCREOZYMIN ON RAT PANCREATIC ENZYME BIOSYNTHESIS

    PubMed Central

    Reggio, H.; Cailla-Deckmyn, H.; Marchis-Mouren, G.

    1971-01-01

    Pancreatic enzyme secretion in rats anesthesized by pentobarbital was stimulated by intravenous perfusion of the hormone pancreozymin, as indicated by a decreased amylase level in the pancreas and by specific, fine structural changes observed in an electron microscope. Rates of protein synthesis were determined by pulse labeling. Amylase, total protein, and valine were purified from pancreas and counted. Pancreozymin promotes an 8 to 10 times increase in the rate of biosynthesis of pancreatic enzymes, as compared to rats similarly anesthesized but without hormone. This stimulation effect is obtained very rapidly (2 hr) and is not inhibited by actinomycin D. Secretin alone has no effect, whereas pentobarbital is inhibitory. PMID:5112644

  6. Effects of clotrimazol on the acute necrotizing pancreatitis in rats.

    PubMed

    Cekic, Arif Burak; Alhan, Etem; Usta, Arif; Türkyılmaz, Serdar; Kural, Birgül Vanizor; Erçin, Cengiz

    2013-12-01

    This study aims to investigate the influence of clotrimazol (CLTZ) on acute necrotizing pancreatitis (ANP) induced by glycodeoxycholic acid in rats. Rats were divided into five groups as sham + saline, sham + CLTZ, sham + polyethylene glycol, ANP + saline, and ANP + CLTZ. ANP in rats was induced by glycodeoxycholic acid. The extent of acinar cell injury, mortality, systemic cardiorespiratory variables, functional capillary density (FCD), renal/hepatic functions, and changes in some enzyme markers for pancreatic and lung tissue were investigated during ANP in rats. The use of CLTZ after the induction of ANP resulted in a significant decrease in the mortality rate, pancreatic necrosis, and serum activity of amylase, alanine aminotransferase, interleukin-6, lactate dehydrogenase in bronchoalveolar lavage fluid, serum concentration of urea, and tissue activity of myeloperoxidase, and malondialdehyde in the pancreas and lung and a significant increase in concentrations of calcium, blood pressure, urine output, pO2, and FCD. This study showed that CLTZ demonstrated beneficial effect on the course of ANP in rats. Therefore, it may be used in the treatment of acute pancreatitis.

  7. Identification and Functional Implications of Sodium/Myo-inositol Cotransporter 1 in Pancreatic Beta-cells and Type 2 Diabetes Mellitus.

    PubMed

    Ting Li, Stephen Yu; Wai Cheng, Sam Tsz; Zhang, Dan; Leung, Po Sing

    2017-02-15

    Myo-inositol (MI), the precursor of the second messenger phosphoinositide (PI), mediates multiple cellular events. Rat islets exhibit active transport of MI, though the mechanism involved remains elusive. Here, we report, for the first time, the expression of sodium/myo-inositol cotransporter 1 (SMIT1) in rat islets and specifically, β-cells. Genetic or pharmacological inhibition of SMIT impaired glucose-stimulated insulin secretion by INS-1E cells, probably via down-regulation of PI signaling. Additionally, we found that SMIT1 expression in INS-1E cells and isolated islets was augmented by acute high-glucose exposure and reduced in chronic hyperglycemia conditions. In corroboration, chronic MI treatment improved the disease phenotypes of diabetic rats and islets. Based on our results, we postulate that the MI transporter SMIT1 is required to maintain a stable PI pool in β-cells in order that PI remains available despite its rapid turnover.

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

    SciTech Connect

    Rashid, Kahkashan; Sil, Parames C.

    2015-02-01

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

  9. Histological changes and antidiabetic activities of Icacina trichantha tuber extract in beta-cells of alloxan induced diabetic rats

    PubMed Central

    Monday, Onakpa Michael; Uzoma, Asuzu Isaac

    2013-01-01

    Objective To investigate the antidiabetic, hypolipidaemic activities and histopathological changes of Icacina trichantha (I. trichantha) tuber extract in alloxan induced diabetic rats. Methods In the present study, 80% methanol extract of I. trichantha tuber was tested on alloxan induced diabetic rats. They were randomly grouped into control (distilled water and glibenclamide) and experimental (200, 400 and 600 mg/kg body weight). Diabetes was induced by a single intraperitoneal injection of 160 mg/kg body weight of alloxan. Blood glucose levels were measured using blood glucose test strips with AccuCheck Advantage II glucometer at 1, 3, 6, and 24 h on the first day and 1 h after treatment on Day 7, 14 and 21. Blood samples were collected and centrifuged to separate serum for estimation of lipid profile and other biochemical parameters. Histopathological changes in diabetic rats pancreas were also studied after extract treatment. Results Daily oral administration of I. trichantha tuber extract (200, 400, and 600 mg/kg body weight) and glibenclamide (2 mg/kg) showed beneficial effects on blood glucose level (P<0.01) as well as improving liver, kidney functions and hyperlipidaemia due to diabetes. The extract had a favourable effect on the histopathological changes of the pancreas in alloxan induced diabetes. Conclusions I. trichantha tuber extracts posses antidiabetic activities as well as improve liver and renal profile and total lipids levels. I. trichantha tuber extracts also have favourable effects to inhibit the histopathological changes of the pancreas in alloxan induced diabetes. PMID:23905020

  10. Pancreatic effect of andrographolide isolated from Andrographis paniculata (Burm. f.) Nees.

    PubMed

    Nugroho, Agung Endro; Rais, Ichwan Ridwan; Setiawan, Iwan; Pratiwi, Pramita Yuli; Hadibarata, Tony; Tegar, Maulana; Pramono, Suwidjiyo

    2014-01-01

    Andrographis paniculata (Burm. f.) Nees is a plant that originates from India and grows widely to Southeast which used for several purposes mainly as treatment of diabetes mellitus so the aim of this study was evaluate andrographolide for its pancreatic effect in neonatal streptozotocin (STZ)-induced diabetic rats, a model of type 2 diabetic rats. Diabetic condition was induced with an intraperitoneal injection of 90 mg kg(-1) streptozotocin in two-day-old rats. After three months, the neonatal STZ-induced diabetic rats were treated with andrographolide or andrographolide-enriched extract of A. paniculata (AEEAP) for 8 consecutive days. Pancreatic effect was evaluated by estimating mainly the preprandial and postprandial blood glucose levels and other parameters such as morphology of pancreatic islet, beta cells density and morphology and immunohistochemically pancreatic insulin. Andrographolide significantly (p < 0.05) decreased the levels of blood glucose and improved diabetic rat islet and beta cells. However, AEEAP exhibited moderate hypoglycaemic effects on the blood glucose levels. Moderate changes in beta cells were observed after AEEAP treatment. They could restore decreasing of pancreatic insulin contents. Based on these results andrographolide and AEEAP exhibited pancreatic actions in neonatal STZ-induced diabetic rats. The activity of andrographolide was more effective than this of AEEAP.

  11. Melatonin reduces pancreatic prostaglandins production and protects against caerulein-induced pancreatitis in rats.

    PubMed

    Chen, Han-Ming; Chen, Jih-Chang; Ng, Chip-Jin; Chiu, De-Fa; Chen, Miin-Fu

    2006-01-01

    Melatonin has been used to treat experimental pancreatitis, although not all the drug's therapeutic mechanisms of melatonin have been defined. Prostaglandins (PGs) are proinflammatory mediators that exert their effects mainly locally during inflammatory diseases. The present study was undertaken to examine whether treatment with melatonin influences local PG production. An acute pancreatitis model in male Sprague-Dawley rats (225-275 g) was established by continuously infusing caerulein (15 mg/kg/hr). Mean arterial pressure and pancreatic perfusion were monitored continuously. Melatonin was delivered via the intraperitoneal route at doses of either 2 or 10 mg/kg, 30 min after caerulein injection. Malondialdehyde and glutathione levels of the pancreas and liver and the trypsinogen activation peptide levels in the serum were measured at the end of the experiment (8 hr after infusion of caerulein). Intraperitoneal injection of melatonin (2 and 10 mg/kg) reduced the reduction in systemic arterial pressure and decreased pancreatic perfusion in the rat model of caerulein pancreatitis. Moreover, melatonin treatment changed local PG production toward control level. Higher dose of melatonin was somewhat more effective in preventing the caerulein-induced alterations than was the lower dose.

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

    PubMed

    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.

  13. In vivo and ex vivo 19-fluorine magnetic resonance imaging and spectroscopy of beta-cells and pancreatic islets using GLUT-2 specific contrast agents.

    PubMed

    Liang, Sayuan; Louchami, Karim; Kolster, Hauke; Jacobsen, Anna; Zhang, Ying; Thimm, Julian; Sener, Abdullah; Thiem, Joachim; Malaisse, Willy; Dresselaers, Tom; Himmelreich, Uwe

    2016-11-01

    The assessment of the β-cell mass in experimental models of diabetes and ultimately in patients is a hallmark to understand the relationship between reduced β-cell mass/function and the onset of diabetes. It has been shown before that the GLUT-2 transporter is highly expressed in both β-cells and hepatocytes and that D-mannoheptulose (DMH) has high uptake specificity for the GLUT-2 transporter. As 19-fluorine MRI has emerged as a new alternative method for MRI cell tracking because it provides potential non-invasive localization and quantification of labeled cells, the purpose of this project is to validate β-cell and pancreatic islet imaging by using fluorinated, GLUT-2 targeting mannoheptulose derivatives ((19) FMH) both in vivo and ex vivo. In this study, we confirmed that, similar to DMH, (19) FMHs inhibit insulin secretion and increase the blood glucose level in mice temporarily (approximately two hours). We were able to assess the distribution of (19) FMHs in vivo with a temporal resolution of about 20 minutes, which showed a quick removal of (19) FMH from the circulation (within two hours). Ex vivo MR spectroscopy confirmed a preferential uptake of (19) FMH in tissue with high expression of the GLUT-2 transporter, such as liver, endocrine pancreas and kidney. No indication of further metabolism was found. In summary, (19) FMHs are potentially suitable for visualizing and tracking of GLUT-2 expressed cells. However, current bottlenecks of this technique related to the quick clearance of the compound and relative low sensitivity of (19) F MRI need to be overcome. Copyright © 2016 John Wiley & Sons, Ltd.

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

    PubMed

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

    2011-10-01

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

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

    PubMed Central

    van der Meulen, Talitha; Huising, Mark O.

    2014-01-01

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

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

    PubMed

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

    2010-03-01

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

  17. Sesamol attenuates oxidative stress-mediated experimental acute pancreatitis in rats.

    PubMed

    Chu, P-Y; Srinivasan, P; Deng, J-F; Liu, M-Y

    2012-04-01

    Acute pancreatitis is a potentially fatal disease with no known cure. The initial events in acute pancreatitis may occur within the acinar cells. We examined the effect of sesamol on (i) a cerulein-induced pancreatic acinar cancer cell line, AR42J, and (ii) cerulein-induced experimental acute pancreatitis in rats. Sesamol inhibited amylase activity and increased cell survival. It also inhibited medium lipid peroxidation and 8-hydroxydeoxyguanosine in AR42J cells compared with the cerulein-alone groups. In addition, in cerulein-treated rats, sesamol inhibited serum amylase and lipase levels, pancreatic edema, and lipid peroxidation, but it increased pancreatic glutathione and nitric oxide levels. Thus, we hypothesize that sesamol attenuates cerulein-induced experimental acute pancreatitis by inhibiting the pancreatic acinar cell death associated with oxidative stress in rats.

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

    PubMed Central

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

    2015-01-01

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

  19. Regulation of inducible nitric oxide synthase expression in beta cells by environmental factors: heavy metals.

    PubMed Central

    Eckhardt, W; Bellmann, K; Kolb, H

    1999-01-01

    The expression of inducible NO synthase (iNOS) in pancreatic islet beta cells modulates endocrine cell functions and, at very high levels of NO production causes beta-cell death. We tested the hypothesis that environmental factors such as heavy-metal salts modulate iNOS expression in beta cells. A rat beta-cell line (insulinoma RINm5F) was cultured in the presence of low-dose interleukin (IL)-1beta for suboptimal induction of iNOS. PbCl2 (0. 1-10 microM) dose-dependently increased NO (measured as nitrite) formation (P<0.001). In contrast, HgCl2 suppressed nitrite production (0.1-10 microM, P<0.05). Measurements of iNOS activity by determining citrulline levels confirmed the potentiating effect of PbCl2 (P<0.05). There was a narrow time window of heavy-metal actions, ranging from -24 h (Hg2+) or -3 h (Pb2+) to +2 h, relative to the addition of IL-1beta. By semi-quantitative reverse transcriptase-PCR, enhanced levels of iNOS mRNA were found in the presence of Pb2+ (P<0.05) and decreased levels in the presence of Hg2+. The amount of iNOS protein as determined by Western blotting was increased in the presence of Pb2+. We conclude that Pb2+ upregulates and Hg2+ suppresses iNOS gene expression at the level of transcription, probably by acting on the signalling pathway. These observations may have important implications for understanding pathological effects of environmental factors on endocrine organ functions. PMID:10051441

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

    PubMed Central

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

    2015-01-01

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

  1. Rehabilitation of adaptive immunity and regeneration of beta cells.

    PubMed

    Pasquali, Lorenzo; Fan, Yong; Trucco, Massimo; Ringquist, Steven

    2006-11-01

    Type 1 Diabetes (T1D) is an autoimmune disease resulting from the destruction of pancreatic insulin-producing beta cells that most frequently occurs in genetically predisposed children. Recent observations illustrating the regenerative capability of the endocrine pancreas in addition to advances in stem cell and gene therapy technologies enable the exploration of alternatives to allogeneic islet transplantation. Living-cell-mediated approaches can abrogate autoimmunity and the consequent destruction of beta cells without the need for immunosuppressive drugs. Such approaches can be used as a foundation for new protocols that more easily translate to the clinical setting. The twin goals of controlling autoimmune disease and promoting stable regeneration of insulin-producing beta cells should be considered the cornerstones of the successful development of a cure for this chronic disease.

  2. Insulin secretion from beta cells within intact islets: location matters.

    PubMed

    Hoang Do, Oanh; Thorn, Peter

    2015-04-01

    The control of hormone secretion is central to body homeostasis, and its dysfunction is important in many diseases. The key cellular steps that lead to hormone secretion have been identified, and the stimulus-secretion pathway is understood in outline for many endocrine cells. In the case of insulin secretion from pancreatic beta cells, this pathway involves the uptake of glucose, cell depolarization, calcium entry, and the triggering of the fusion of insulin-containing granules with the cell membrane. The wealth of information on the control of insulin secretion has largely been obtained from isolated single-cell studies. However, physiologically, beta cells exist within the islets of Langerhans, with structural and functional specializations that are not preserved in single-cell cultures. This review focuses on recent work that is revealing distinct aspects of insulin secretion from beta cells within the islet.

  3. [Ultrastructural changes in the pancreas of rats with acute pancreatitis after semax administration].

    PubMed

    Ivanov, Iu V

    2000-01-01

    Semax favorably affects ultrastructural changes in the pancreas of rats with acute pancreatitis (AP): a single introduction of semax (0.1 mg/kg) into the pancreatic duct of rats with AP model prevents increased necrosis of the acinar tissues and inhibits purulent inflammation of the necrotised lobules by inducing their sclerosis and atrophy, thus retaining large areas of the pancreas intact.

  4. Pancreatic functions in high salt fed female rats

    PubMed Central

    Lasheen, Noha N

    2015-01-01

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

  5. cAMP-dependent protein kinase and Ca2+ influx through L-type voltage-gated calcium channels mediate Raf-independent activation of extracellular regulated kinase in response to glucagon-like peptide-1 in pancreatic beta-cells.

    PubMed

    Gomez, Edith; Pritchard, Catrin; Herbert, Terence P

    2002-12-13

    Glucagon like peptide-1 (GLP1) is a G(s)-coupled receptor agonist that exerts multiple effects on pancreatic beta-cells, including the stimulation of insulin gene expression and secretion. In this report, we show that treatment of the mouse pancreatic beta-cell line MIN6 with GLP1 leads to the glucose-dependent activation of Erk. These effects are mimicked by forskolin, a direct activator of adenylate cyclase, and blocked by H89, an inhibitor of cAMP-dependent protein kinase. Additionally, we provide evidence that GLP1-stimulated activation of Erk requires an influx of calcium through L-type voltage-gated calcium channels and the activation of calcium/calmodulin-dependent protein kinase II. GLP1-stimulated activation of Erk is blocked by inhibitors of MEK, but GLP1 does not induce the activation of A-Raf, B-Raf, C-Raf, or Ras. Additionally, dominant negative forms of Ras(N17) and Rap1(N17) fail to block GLP1-stimulated activation of Erk. In conclusion, our results indicate that, in the presence of stimulatory concentrations of glucose, GLP1 stimulates the activation of Erk through a mechanism dependent on MEK but independent of both Raf and Ras. This requires 1) the activation of cAMP-dependent protein kinase, 2) an influx of extracellular Ca(2+) through L-type voltage-gated calcium channels, and 3) the activation of CaM kinase II.

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

    PubMed

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

    1987-01-01

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

  7. Secondary prevention of type 1 diabetes mellitus: stopping immune destruction and promoting beta-cell regeneration.

    PubMed

    Couri, C E B; Foss, M C; Voltarelli, J C

    2006-10-01

    Type 1 diabetes mellitus results from a cell-mediated autoimmune attack against pancreatic beta-cells. Traditional treatments involve numerous daily insulin dosages/injections and rigorous glucose control. Many efforts toward the identification of beta-cell precursors have been made not only with the aim of understanding the physiology of islet regeneration, but also as an alternative way to produce beta-cells to be used in protocols of islet transplantation. In this review, we summarize the most recent studies related to precursor cells implicated in the regeneration process. These include embryonic stem cells, pancreas-derived multipotent precursors, pancreatic ductal cells, hematopoietic stem cells, mesenchymal stem cells, hepatic oval cells, and mature beta-cells. There is controversial evidence of the potential of these cell sources to regenerate beta-cell mass in diabetic patients. However, clinical trials using embryonic stem cells, umbilical cord blood or adult bone marrow stem cells are under way. The results of various immunosuppressive regimens aiming at blocking autoimmunity against pancreatic beta-cells and promoting beta-cell preservation are also analyzed. Most of these regimens provide transient and partial effect on insulin requirements, but new regimens are beginning to be tested. Our own clinical trial combines a high dose immunosuppression with mobilized peripheral blood hematopoietic stem cell transplantation in early-onset type 1 diabetes mellitus.

  8. In vivo characterization of developing chronic pancreatitis in rats.

    PubMed

    Glawe, Claudia; Emmrich, Jörg; Sparmann, Gisela; Vollmar, Brigitte

    2005-02-01

    Despite numerous experimental and clinical investigations, there is no unifying concept on pathophysiology and pathogenesis of chronic pancreatitis. Defining the interplay between pancreatic microcirculation and parenchymal tissue, we will provide a basis for the better understanding of pancreatic fibrogenesis using in vivo high-resolution multifluorescence microscopy in dibutyltin chloride (DBTC)-exposed rats. Pancreatic microcirculation at days 3 and 7 after DBTC revealed leukocyte activation with a two-fold higher fraction of rolling cells and a nine- to 10-fold increase of cells firmly adherent to the endothelial lining, followed by subsequent transendothelial migration into tissue, as given by chloracetate esterase histology. In vivo staining of acinar tissue with bisbenzimide presented single cells exhibiting nuclear chromatin condensation and fragmentation. Apoptotic cell death was confirmed by immunohistochemical staining for active caspase-3 as well as by TUNEL analysis. Necrotic cells were found dispersed throughout the exocrine tissue under observation. Both modes of cell death were found highest in extent at days 3 and 7 with 15-20 cells/mm2, but progressively decreased below 10 cells/mm2 up to 28 days after DBTC. By means of in vivo microscopy yellow-green autofluorescent collagen deposits were found at day 7 and progressively increased up to approximately 12% at day 28 after DBTC. Concomitantly, density of capillaries progressively decreased and capillaries failing to conduct blood flow became apparent. Present on-line analysis indicates an early inflammatory response with acinar cell death, most probably triggering progression of disease with collagen deposition, capillary rarefication and manifestation of perfusion failure. These temporal and spatial multiparameter measurements of the in vivo microenvironment provide new insights into the pathological processes of pancreatic fibrogenesis.

  9. Augmented secretion of lysosomal enzyme into pancreatic juice after short term obstruction of the pancreatic duct in rats.

    PubMed

    Hirano, T; Manabe, T; Kyogoku, T; Ando, K; Yotsumoto, F; Imanishi, K; Ohshio, G

    1992-05-01

    To find out if and when lysosomal enzymes are excreted into pancreatic juice in physiological and pathological conditions, the changes in the secretion of cathepsin B into pancreatic juice were investigated in 66 Wistar rats with cannulation of common pancreatic-biliary duct and common bile duct, and infusions of caerulein and secretin. In a separate experiment ducts were cannulated and secretin infused as before, but in one group the ducts were "obstructed" and in another they were allowed to remain patent. Obstruction of the pancreatic duct for three hours caused a moderate significant rise in serum amylase activity. Cathepsin B activity in the pancreatic subcellular fractions was redistributed, and the amount of cathepsin B increased. In rats with obstructed ducts the secretion of cathepsin B and other lysosomal enzymes that were stimulated by caerulein was significantly greater than in the animals in which the ducts remained patent. Lysosomal enzymes associated with zymogen granules are secreted into pancreatic juice together with digestive enzymes after stimulation by gut hormones, and they may have pathophysiological roles in pancreatic juice.

  10. Identification of T cell subsets and class I and class II antigen expression in islet grafts and pancreatic islets of diabetic BioBreeding/Worcester rats.

    PubMed Central

    Weringer, E. J.; Like, A. A.

    1988-01-01

    The BioBreeding/Worcester (BB/Wor) rat develops a spontaneous disorder that closely resembles human insulin-dependent (Type I) diabetes mellitus. The syndrome is preceded by lymphocytic insulitis that destroys pancreatic beta cells. The morphologic features of the spontaneous insulitis lesions are also observed within islets transplanted beneath the renal capsule of diabetes-prone and diabetic animals. This study reports the results of experiments in which immunohistochemical techniques were used to characterize the phenotype of the infiltrating mononuclear cells and detect the expression of class I and class II MHC antigens in native islets and islet transplants in diabetic and diabetes-prone BB/Wor rats. The infiltrates within native pancreatic islets and islet grafts were comprised predominantly of Ia+ cells (dendritic cells and macrophages) CD4+ cells (helper/inducer lymphocytes and macrophages), CD5+ (pan-T) cells and smaller numbers of CD8+ (cytotoxic/suppressor and NK) cells. Pancreatic and graft insulitis were accompanied by markedly enhanced class I antigen expression on islet and exocrine cells. Class II (Ia) antigens were not detected on normal islet cells, islets undergoing insulitis or on islet transplants subjected to immune attack. In islet grafts stained with polymorphic MAbs that distinguish Ia antigens of donor and host origin, Ia antigen expression was limited to infiltrating dendritic cells and macrophages of host origin. It is concluded that the phenotypes of infiltrating mononuclear cells that comprise the insulitis lesion in spontaneous BB/Wor diabetes, and the inflammatory attack on islets transplanted into diabetic BB/Wor rats are the same, that pancreatic islet and graft insulitis occur in the presence of enhanced class I antigen expression but in the absence of class II antigen expression, and that infiltrating Ia+ cells within islet grafts are exclusively of recipient (BB/Wor) origin and may explain the initiation of immune insulitis

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

    PubMed

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

    2016-06-01

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

  12. Very slow turnover of beta-cells in aged adult mice.

    PubMed

    Teta, Monica; Long, Simon Y; Wartschow, Lynn M; Rankin, Matthew M; Kushner, Jake A

    2005-09-01

    Although many signaling pathways have been shown to promote beta-cell growth, surprisingly little is known about the normal life cycle of preexisting beta-cells or the signaling pathways required for beta-cell survival. Adult beta-cells have been speculated to have a finite life span, with ongoing adult beta-cell replication throughout life to replace lost cells. However, little solid evidence supports this idea. To more accurately measure adult beta-cell turnover, we performed continuous long-term labeling of proliferating cells with the DNA precursor analog 5-bromo-2-deoxyuridine (BrdU) in 1-year-old mice. We show that beta-cells of aged adult mice have extremely low rates of replication, with minimal evidence of turnover. Although some pancreatic components acquired BrdU label in a linear fashion, only 1 in approximately 1,400 adult beta-cells were found to undergo replication per day. We conclude that adult beta-cells are very long lived.

  13. Effects of a new cholecystokinin antagonist, TS-941, on experimental acute pancreatitis in rats.

    PubMed

    Wang, Y; Naruse, S; Kitagawa, M; Ishiguro, H; Nakae, Y; Yoshikawa, T; Hayakawa, T

    1998-10-01

    The effects of a new benzodiazepine-derivative, cholecystokinin receptor antagonist, TS-941, on experimental acute pancreatitis were studied in rats. Hemorrhagic pancreatitis was induced by an infusion of a mixture of trypsin and taurocholate into the pancreatic duct. Edematous pancreatitis was induced by intraperitoneal injection of 40 microg/kg body weight of cerulein at 0 and 1 h after the start of the experiment. TS-941 (3 mg/kg) was injected subcutaneously immediately and 3 h after the induction of pancreatitis. In trypsin-taurocholate-induced pancreatitis, TS-941, with or without the synthetic trypsin inhibitor ONO-3403, had no beneficial effects on the survival rate, pancreatic wet weight, and serum pancreatic enzymes. In cerulein-induced pancreatitis, the treatment with TS-941 significantly reduced the increases of pancreatic wet weight and serum amylase and lipase. Plasma trypsinogen activation peptide (TAP) significantly rose 1 h after the first injection of cerulein. TS-941 inhibited the liberation of TAP in cerulein-induced pancreatitis. These results show that TS-941 is effective for prevention of cerulein-induced edematous pancreatitis. ONO-3403 has beneficial effects on trypsin-taurocholate-induced hemorrhagic pancreatitis, but the combination of TS-941 and ONO-3403 has no additive effect.

  14. TRIB3 [corrected] is implicated in glucotoxicity- and endoplasmic reticulum-stress-induced [corrected] beta-cell apoptosis.

    PubMed

    Qian, Bo; Wang, Haiyan; Men, Xiuli; Zhang, Wenjian; Cai, Hanqing; Xu, Shiqing; Xu, Yaping; Ye, Liya; Wollheim, Claes B; Lou, Jinning

    2008-12-01

    We found that TRIB3, [corrected] an endogenous inhibitor of Akt (PKB), is expressed in pancreatic beta-cells. The TRIB3 [corrected] expression is significantly increased in islets isolated from hyperglycemic Goto-Kakizaki rats compared with normal glycemic controls. In vitro high glucose treatment also resulted in increased TRIB3 [corrected] expression in rat INS1 cells. To investigate the role of TRIB3 [corrected] in the regulation of beta-cell function, we established an INS1 stable cell line allowing inducible expression of TRIB3. [corrected] We demonstrated that overexpression of TRIB3 [corrected] mimicked the glucotoxic effects on insulin secretion and cell growth in INS1 cells. Moreover, induction of TRIB3 [corrected] also synergistically enhanced high-glucose-elicited apoptosis in INS1 cells, whereas siRNA knock-down of TRIB3 [corrected] showed the opposite effects. We also confirmed that the DeltaPsim of mitochondria was decreased, caspase-3 activity was up-regulated and reactive oxygen species content was increased in TRIB3 [corrected] overexpressing beta cells in high glucose condition. Most interestingly, the oestrogen receptor (ER) stress inducer, thapsigargin, mimicked the high glucose effects on up-regulation of TRIB3 [corrected] and generation of apoptosis in cultured INS1 cells. These effects were specifically prevented by siRNA knock down of TRIB3. [corrected] We therefore conclude that TRIB3 [corrected] is implicated in glucotoxicity- and ER stress-induced beta-cell failure.TRIB3 [corrected] could be a potential pharmacological target for prevention and treatment of type 2 diabetes.

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

    PubMed

    Yechoor, Vijay; Chan, Lawrence

    2010-08-01

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

  16. Jejunal bypass stimulation of pancreatic growth and cholecystokinin secretion in rats: importance of luminal nutrients.

    PubMed Central

    Levan, V H; Liddle, R A; Green, G M

    1987-01-01

    The effect of jejunal bypass on pancreatic growth and plasma cholecystokinin (CCK) was investigated in rats. Rats underwent bypass of jejunum or sham operation. Rats with jejunal bypass were further divided into three groups; one group received a continuous infusion of a partially hydrolysed liquid diet (Vital) into the bypassed jejunum; a second group received the nutrient solution mixed with trypsin and infused into the bypassed jejunum; the third bypass group did not receive infusion of nutrient or trypsin into the jejunum. Jejunal bypass alone did not significantly stimulate pancreatic growth or DNA content at one or two weeks postoperative. Infusion of nutrient solution into the bypassed jejunum stimulated pancreatic growth and DNA content, with maximal increases of 185% and 181% for pancreatic weight and DNA content, respectively, at two weeks. This coincided with significant increases in postabsorptive plasma CCK concentrations. Infusion of pancreatic proteases into the bypassed jejunum partially reversed the effects of nutrient infusion. These results suggest that exclusion of bile-pancreatic juice or pancreatic proteases from the jejunum does not lead to maximal release of CCK unless the jejunum receives luminal nutrients. It is proposed that CCK release from rat jejunum occurs spontaneously in the absence of pancreatic proteases, and that luminal nutrients in bypassed jejunum increase plasma CCK and stimulate pancreatic growth by maintaining synthesis of CCK. PMID:3692314

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

    PubMed Central

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

    2010-01-01

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

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

    PubMed

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

    2009-06-01

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

  19. An immunocytochemical and morphometric study of the rat pancreatic islets.

    PubMed Central

    Elayat, A A; el-Naggar, M M; Tahir, M

    1995-01-01

    The rat pancreas has frequently been used as an animal model to study changes in islet cells in pathological conditions, such as diabetes mellitus and islet cell tumours, but detailed quantitative data on the islets are not available. This study was therefore undertaken to investigate (1) the volume density of pancreatic islets, (2) islet diameter, islet volume and islet cell number and (3) islet cell pattern, i.e. the distribution, volume and number of each cell type per islet. The study also investigated the possibility of differences in various pancreatic regions derived from the dorsal primordium. The rat pancreas was divided into 4 regions: lower duodenal (derived from the ventral primordium) and upper duodenal, gastric and splenic regions (derived from the dorsal primordium). Sections were stained immunocytochemically with anti-insulin (B cells), antiglucagon (A cells), antisomatostatin (D cells) and antipancreatic polypeptide (PP cells) antibodies, and were used for morphometric analysis. A total of 1292 islets was examined, 328 from the lower duodenal, 245 from the upper duodenal, 314 from the gastric and 405 from the splenic regions. The mean volume density of the islets per pancreatic tissue was found to be 2.6 +/- 0.1%, 2.3 +/- 0.1%, 2.9 +/- 0.2% and 3.3 +/- 0.2%, in the lower duodenal, upper duodenal, gastric and splenic regions, respectively. The size-frequency distribution of the profile diameters of the islets showed an overall shift of all the size classes towards smaller sizes in the upper duodenal region, and towards larger sizes in the splenic region, as compared with the corresponding classes of the other regions.(ABSTRACT TRUNCATED AT 250 WORDS) Images Fig. 4 Fig. 5 PMID:7559135

  20. Characterisation of Age-Dependent Beta Cell Dynamics in the Male db/db Mice

    PubMed Central

    Dalbøge, Louise S.; Almholt, Dorthe L. C.; Neerup, Trine S. R.; Vassiliadis, Efstathios; Vrang, Niels; Pedersen, Lars; Fosgerau, Keld; Jelsing, Jacob

    2013-01-01

    Aim To characterise changes in pancreatic beta cell mass during the development of diabetes in untreated male C57BLKS/J db/db mice. Methods Blood samples were collected from a total of 72 untreated male db/db mice aged 5, 6, 8, 10, 12, 14, 18, 24 and 34 weeks, for measurement of terminal blood glucose, HbA1c, plasma insulin, and C-peptide. Pancreata were removed for quantification of beta cell mass, islet numbers as well as proliferation and apoptosis by immunohistochemistry and stereology. Results Total pancreatic beta cell mass increased significantly from 2.1 ± 0.3 mg in mice aged 5 weeks to a peak value of 4.84 ± 0.26 mg (P < 0.05) in 12-week-old mice, then gradually decreased to 3.27 ± 0.44 mg in mice aged 34 weeks. Analysis of islets in the 5-, 10-, and 24-week age groups showed increased beta cell proliferation in the 10-week-old animals whereas a low proliferation is seen in older animals. The expansion in beta cell mass was driven by an increase in mean islet mass as the total number of islets was unchanged in the three groups. Conclusions/Interpretation The age-dependent beta cell dynamics in male db/db mice has been described from 5-34 weeks of age and at the same time alterations in insulin/glucose homeostasis were assessed. High beta cell proliferation and increased beta cell mass occur in young animals followed by a gradual decline characterised by a low beta cell proliferation in older animals. The expansion of beta cell mass was caused by an increase in mean islet mass and not islet number. PMID:24324833

  1. Therapeutic effect of ghrelin in the course of cerulein-induced acute pancreatitis in rats.

    PubMed

    Warzecha, Z; Ceranowicz, P; Dembinski, A; Cieszkowski, J; Kusnierz-Cabala, B; Tomaszewska, R; Kuwahara, A; Kato, I

    2010-08-01

    Recent studies have shown that pretreatment with ghrelin exhibits protective effect in the gut. Administration of ghrelin reduces gastric mucosal damage, as well as inhibits the development of experimental pancreatitis. However, this protective effect requires administration of ghrelin before gastric or pancreatic damage and thus has a limited clinical value. The aim of present study was to assess the influence of ghrelin administered after development of acute pancreatitis on the course of this disease. Acute pancreatitis was induced by cerulein. Ghrelin was administered twice a day for 1, 2, 4, 6 or 9 days at the dose of 4, 8 or 16 nmol/kg/dose. The first dose of ghrelin was given 24 hours after last injection of cerulein. The severity of acute pancreatitis was assessed between 0 h and 10 days after cessation of cerulein administration. Administration of caerulein led to the development of acute edematous pancreatitis and maximal severity of this disease was observed 24 hours after induction of pancreatitis. Treatment with ghrelin reduced morphological signs of pancreatic damage such as pancreatic edema, leukocyte infiltration and vacuolization of acinar cells, and led to earlier regeneration of the pancreas. Also biochemical indexes of the severity of acute pancreatitis, serum activity of lipase and amylase were significantly reduced in animals treated with ghrelin. These effects were accompanied by an increase in the pancreatic DNA synthesis and a decrease in serum level of pro-inflammatory interleukin-1b. Administration of ghrelin improved pancreatic blood flow in rats with acute pancreatitis. We conclude that: (1) treatment with ghrelin exhibits therapeutic effect in caerulein-induced experimental acute pancreatitis; (2) this effect is related, at least in part, to the improvement of pancreatic blood flow, reduction in proinflammatory interleukin-1beta and stimulation of pancreatic cell proliferation.

  2. Biliopancreatic duct injection of ethanol as an experimental model of acute and chronic pancreatitis in rats.

    PubMed

    Unal, Ethem; Atalay, Suleyman; Tolan, Huseyin Kerem; Yuksekdag, Sema; Yucel, Metin; Acar, Aylin; Basak, Fatih; Gunes, Pembegul; Bas, Gurhan

    2015-01-01

    In the present study, we described an easily reproducable experimental pancreatits model induced by biliopancreatic duct injection of ethyl alcohol. Seventy Wistar albino rats were divided equally into seven groups randomly: the control group (group 1), acute pancreatitis groups; induced by 20% ethanol (group 2), 48% ethanol (group 3), 80% ethanol (group 4), chronic pancreatitis groups; induced by 20% ethanol (group 5), 48% ethanol (group 6) and by 80% ethanol (group 7). Acute pancreatitis groups were sacrified on postoperative day 3, while the control group and chronic pancreatitis groups were killed on postoperative day 7. Histopathologic evaluation was done, and P < 0.05 was accepted as statistically significant. All rats in group 3 developed acute pancreatitis (100%). Inflammatory infiltration of neutrophils and mononuclear cells, interstitial edema, and focal necrotic areas were seen in the pancreatic tissues. Similarly, all rats in group 6 developed chronic pancreatitis (100%). Interstitial fibrosis, lymphotic infiltration, ductal dilatation, acinar cell atrophy, periductal hyperplasia were seen in the pancreatic tissues. Mortality was seen only in group 7. The biliopancreatic ductal injection of 48% ethanol induced acute and chronic pancreatitis has 100% success rate.

  3. Effect of endogenous cholecystokinin on the course of acute pancreatitis in rats

    PubMed Central

    Jia, Dongmei; Yamamoto, Mitsuyoshi; Otsuki, Makoto

    2015-01-01

    AIM: To examine the effects of pancreatic rest, stimulation and rest/stimulation on the natural course of recovery after acute pancreatitis. METHODS: Acute hemorrhagic pancreatitis (AP) was induced in male rats by intraductal infusion of 40 μL/100 g body weight of 3% sodium taurocholate. All rats took food ad libitum. At 24 h after induction of AP, rats were divided into four groups: control (AP-C), pancreas rest (AP-R), stimulation (AP-S), and rest/stimulation (AP-R/S). Rats in the AP-C, AP-R and AP-S groups received oral administration of 2 mL/kg body weight saline, cholecystokinin (CCK)-1 receptor antagonist, and endogenous CCK release stimulant, respectively, twice daily for 10 d, while those in the AP-R/S group received twice daily CCK-1 receptor antagonist for the first 5 d followed by twice daily CCK release stimulant for 5 d. Rats without any treatment were used as control group (Control). Biochemical and histological changes in the pancreas, and secretory function were evaluated on day 12 at 24 h after the last treatment. RESULTS: Feeding ad libitum (AP-C) delayed biochemical, histological and functional recovery from AP. In AP-C rats, bombesin-stimulated pancreatic secretory function and HOMA-β-cell score were significantly lower than those in other groups of rats. In AP-R rats, protein per DNA ratio and pancreatic exocrine secretory function were significantly low compared with those in Control rats. In AP-S and AP-R/S rats, the above parameters recovered to the Control levels. Bombesin-stimulated pancreatic exocrine response in AP-R/S rats was higher than in AP-S rats and almost returned to control levels. In the pancreas of AP-C rats, destruction of pancreatic acini, marked infiltration of inflammatory cells, and strong expression of α-smooth muscle actin, tumor necrosis factor-α and interleukin-1β were seen. Pancreatic rest reversed these histological alterations, but not atrophy of pancreatic acini and mild infiltration of inflammatory cells. In

  4. Inhibition of rat and bovine trypsins and chymotrypsins by soybean, bovine basic pancreatic, and bovine colostrum trypsin inhibitors.

    PubMed

    Esparza, I; Brock, J H

    1978-01-01

    1. Bovine (Bos taurus) trypsin and trypsin activity in rat (Rattus norvegicus) pancreatic extract were inhibited by soybean trypsin inhibitor and by bovine basic pancreatic and colostrum inhibitors. 2. Bovine alpha-chymotrypsin was inhibited by soybean and bovine basic pancreatic inhibitors but only weakly by colostrum inhibitor. 3. Chymotrypsin activity in rat pancreatic extract was due to at least three different components against all of which the inhibitors were largely ineffective. 4. It is concluded that bovine colostrum inhibitor has a more limited inhibition spectrum than the phylogenetically related basic pancreatic inhibitor which, in turn, is less active against rat than against bovine enzymes.

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

    SciTech Connect

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

    1988-07-01

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

  6. Cerulein-induced acute pancreatitis in rats--does bacterial translocation occur via a transperitoneal pathway?

    PubMed

    Arendt, T; Wendt, M; Olszewski, M; Falkenhagen, U; Stoffregen, C; Fölsch, U R

    1997-10-01

    Bacterial infectious complications are the most common cause of morbidity and mortality associated with acute pancreatitis. Most pathogens are common gastrointestinal flora, indicating that the gut is the source of pancreatitis-related infections. However, the route whereby the microorganisms reach distant organs remains speculative. We tested the hypothesis that spread of bacteria occurs via a transperitoneal pathway. Acute interstitial pancreatitis (AIP) was induced in antibiotic (gentamicin, bacithracin, neomycin)-decontaminated rats by intravenous infusion of cerulein. Effects of pancreatic necrosis (PN) were studied in rats that received additional injections into the peritoneal cavity of pancreatic tissue obtained from donor rats. The rats were inoculated with Escherichia coli (O2:KN:H18) resistant to the antibiotics used for decontamination either orally (10(12) microorganisms; experiment I) or intraperitoneally (10(8) microorganisms; experiment II). Moreover, the rat peritoneal cavity wash was inoculated with 10(8) E. coli in vitro (experiment III). In rats with AIP and PN, recovery of the bacteria from liver, spleen, pancreas, lung, and blood following oral inoculation demonstrated that acute pancreatitis promotes bacterial translocation from the gut. The absence of E. coli in these organs following intraperitoneal inoculation showed that the bacteria do not spread from the peritoneal cavity. Rats with PN cleared E. coli from the peritoneal cavity in a shorter period than rats with AIP and controls (5 vs. 7 and 8 days; p < 0.05). The multiplication rate of E. coli in peritoneal cavity wash was lower in rats with PN than in rats with AIP and controls (p < 0.01). We conclude that (1) translocation of E. coli from the gut during cerulein-induced acute pancreatitis occurs via nonperitoneal pathways, (2) the peritoneal cavity acts as a trap for the bacteria rather than a source of bacterial seeding, and (3) PN impairs survival of E. coli in the peritoneal

  7. Cannabinoid HU210 protects isolated rat stomach against impairment caused by serum of rats with experimental acute pancreatitis.

    PubMed

    Cao, Ming-hua; Li, Yong-yu; Xu, Jing; Feng, Ya-jing; Lin, Xu-hong; Li, Kun; Han, Tong; Chen, Chang-jie

    2012-01-01

    Acute pancreatitis (AP), especially severe acute pancreatitis often causes extra-pancreatic complications, such as acute gastrointestinal mucosal lesion (AGML) which is accompanied by a considerably high mortality, yet the pathogenesis of AP-induced AGML is still not fully understood. In this report, we investigated the alterations of serum components and gastric endocrine and exocrine functions in rats with experimental acute pancreatitis, and studied the possible contributions of these alterations in the pathogenesis of AGML. In addition, we explored the intervention effects of cannabinoid receptor agonist HU210 and antagonist AM251 on isolated and serum-perfused rat stomach. Our results showed that the AGML occurred after 5 h of AP replication, and the body homeostasis was disturbed in AP rat, with increased levels of pancreatic enzymes, lipopolysaccharide (LPS), proinflammtory cytokines and chemokines in the blood, and an imbalance of the gastric secretion function. Perfusing the isolated rat stomach with the AP rat serum caused morphological changes in the stomach, accompanied with a significant increment of pepsin and [H+] release, and increased gastrin and decreased somatostatin secretion. HU210 reversed the AP-serum-induced rat pathological alterations, including the reversal of transformation of the gastric morphology to certain degree. The results from this study prove that the inflammatory responses and the imbalance of the gastric secretion during the development of AP are responsible for the pathogenesis of AGML, and suggest the therapeutic potential of HU210 for AGML associated with acute pancreatitis.

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

    PubMed

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

    2014-01-01

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

  9. Alcohol causes a fatty pancreas. A rat model of ethanol-induced pancreatic steatosis.

    PubMed

    Wilson, J S; Colley, P W; Sosula, L; Pirola, R C; Chapman, B A; Somer, J B

    1982-01-01

    To develop an animal mode of alcoholic pancreatic steatosis, female Wistar rats were pair fed liquid diets, containing ethanol as 36% of calories or an isocaloric amount of carbohydrate for 3 weeks. Electron microscopic examination showed lipid vesicles localized principally at the bases of pancreatic acinar cells in the ethanol-fed rats. Ethanol feeding significantly increased pancreatic content of cholesteryl ester without changing levels of other lipids. Ethanol feeding enhanced labeled acetate, palmitate, oleate, and linoleate incorporation into cholesteryl ester. Therefore, increased esterification of cholesterol may, in part, explain the observed accumulation of cholesteryl ester.

  10. The effect of phenylbutazone on acute hemorrhagic pancreatitis in the rat.

    PubMed

    Louagie, Y; Hancotte-Lahaye, C; Delloye, C; Mairy, Y; De Muylder, C

    1984-01-01

    The effect of phenylbutazone on acute experimental pancreatitis was investigated in the rat. Severe necrotico-hemorrhagic pancreatitis was produced by intraductal injection of trypsin. Pretreatment by phenylbutazone did not alter the mortality rate but reduced the severity of pancreatitis as was demonstrated by histological quantification (total score 13.35 +/- 0.80 in treated rats versus 17.67 +/- 0.69 in the control group; P less than 0.01). The protective effect of phenylbutazone seems to be related to the specific anti-inflammatory properties of the drug and not to inhibition of prostaglandin synthesis.

  11. Acetyl-L-carnitine ameliorates caerulein-induced acute pancreatitis in rats.

    PubMed

    Arafa, Hossam M M; Hemeida, Ramadan A M; Hassan, Mohamed I A; Abdel-Wahab, Mohammed H; Badary, Osama A; Hamada, Farid M A

    2009-07-01

    In the present study, we have addressed the possible protective role of acetyl-L-carnitine in caerulein-induced acute pancreatitis in male Swiss albino rats. Acute pancreatitis paradigm was developed by challenging animals with a supramaximal dose of caerulein (20 microg/kg, SC) four times at hourly intervals. Caerulein induced acute pancreatitis that was well-characterized morphologically and biochemically. Severe oedema with marked increased relative pancreatic weight, marked atrophy of acini with increased interacinar spaces, vacuolization, and extensive leucocytic infiltration were diagnostic fingerprints of the pancreatitis phenotype. A biochemical test battery that confirmed the model comprised increased plasma amylase and lipase activities, calcium levels as well as increased pancreatic enzymatic myeloperoxidase and glutathione-S-transferase activities, beside increased pancreatic contents of nitric oxide and malondialdehyde and reduced pancreatic glutathione level. Prior administration of acetyl-L-carnitine (200 mg/kg, IP) for seven consecutive days ahead of caerulein challenge alleviated all the histological and biochemical manifestations of acute pancreatitis. These results suggest a possible protective role of the carnitine ester in such a murine acute pancreatitis model probably via regulation of the oxidant/antioxidant balance, beside modulation of the myeloperoxidase and nitric oxide systems, which are involved in the inflammatory cascade that most often associate the disease.

  12. Glycemic control in diabetes is restored by therapeutic manipulation of cytokines that regulate beta cell stress.

    PubMed

    Hasnain, Sumaira Z; Borg, Danielle J; Harcourt, Brooke E; Tong, Hui; Sheng, Yonghua H; Ng, Choa Ping; Das, Indrajit; Wang, Ran; Chen, Alice C-H; Loudovaris, Thomas; Kay, Thomas W; Thomas, Helen E; Whitehead, Jonathan P; Forbes, Josephine M; Prins, Johannes B; McGuckin, Michael A

    2014-12-01

    In type 2 diabetes, hyperglycemia is present when an increased demand for insulin, typically due to insulin resistance, is not met as a result of progressive pancreatic beta cell dysfunction. This defect in beta cell activity is typically characterized by impaired insulin biosynthesis and secretion, usually accompanied by oxidative and endoplasmic reticulum (ER) stress. We demonstrate that multiple inflammatory cytokines elevated in diabetic pancreatic islets induce beta cell oxidative and ER stress, with interleukin-23 (IL-23), IL-24 and IL-33 being the most potent. Conversely, we show that islet-endogenous and exogenous IL-22, by regulating oxidative stress pathways, suppresses oxidative and ER stress caused by cytokines or glucolipotoxicity in mouse and human beta cells. In obese mice, antibody neutralization of IL-23 or IL-24 partially reduced beta cell ER stress and improved glucose tolerance, whereas IL-22 administration modulated oxidative stress regulatory genes in islets, suppressed ER stress and inflammation, promoted secretion of high-quality efficacious insulin and fully restored glucose homeostasis followed by restitution of insulin sensitivity. Thus, therapeutic manipulation of immune regulators of beta cell stress reverses the hyperglycemia central to diabetes pathology.

  13. Administration of Lupinus albus gamma conglutin (Cγ) to n5 STZ rats augmented Ins-1 gene expression and pancreatic insulin content.

    PubMed

    Vargas-Guerrero, Belinda; García-López, Pedro M; Martínez-Ayala, Alma L; Domínguez-Rosales, José A; Gurrola-Díaz, Carmen M

    2014-09-01

    Several studies support the health-promoting benefits of lupins, particularly lupin proteins. It has been demonstrated that Lupinus albus gamma conglutin (Cγ) protein lowered blood glucose levels; thus, Cγ showed promise as a new anti-diabetic compound for type 2 diabetes (T2D) treatment. The aim of this study was to evaluate the effect of Cγ on Ins-1 gene expression and on pancreatic insulin content in streptozotocin-mediated diabetic rats. Cγ was isolated from Lupinus albus seeds. Its identification was confirmed with polyacrylamide gel electrophoresis under native and denaturing conditions. We used streptozotocin (STZ) to induce T2D on the 5th day of life of newborn male Wistar rats (n5-STZ). After 20 weeks post-induction, these animals (glycemia > 200 mg/dL) were randomly assigned to three groups that received the following one-week treatments: vehicle, 0.90% w/v NaCl (n5 STZ-Ctrl); glibenclamide, 10 mg/kg (n5 STZ-Glib); or Cγ, 120 mg/kg (n5 STZ-Cγ). Glucose and insulin levels were measured before and after treatment. Ins-1 gene expression was quantified using real time polymerase chain reaction and the pancreatic insulin content was evaluated with immunohistochemistry. Post-treatment, the n5 STZ-Cγ and n5 STZ-Glib groups showed reductions in glucose, increments in serum insulin, and increases in Ins-1 gene expression and beta cell insulin content compared to the n5 STZ-Ctrl group. The results showed that Cγ had beneficial effects on Ins-1 gene expression and pancreatic insulin content. These biological effects of Cγ strengthen its promising potential as a nutraceutical and/or new agent for controlling hyperglycemia.

  14. Effects of Baicalin on inflammatory mediators and pancreatic acinar cell apoptosis in rats with sever acute pancreatitis

    PubMed Central

    Xiping, Zhang; Hua, Tian; Hanqing, Chen; Li, Chen; Binyan, Yu; Jing, Ma

    2009-01-01

    BACKGROUND: To investigate the effects of Baicalin and Octreotide on inflammatory mediators and pancreatic acinar cells apoptosis of rats with severe acute pancreatitis (SAP). METHODS: SD rats were randomly divided into sham operated group (I group), model control group (II group), Baicalin treated group (III group) and Octreotide treated group (IV group). Each group was also divided into subgroup of 3, 6 and 12 h (n = 15). The mortality rate, ascites/body weight ratio as well as the level of endotoxin, NO and ET-1 in blood were measured. The pathological severity score of pancreas, apoptotic indexes, and expression levels of Bax and Bcl-2 proteins in each group were investigated. RESULTS: The survival rate of III and IV group has a significant difference compared with II group (P12 h < 0.05). The ascites volume, contents of inflammatory mediators in blood and pathological severity score of pancreas of III and IV group declined at different degrees compared to II group (P < 0.05, P < 0.01 or P < 0.001). Apoptotic index in III group was significantly higher than that in II group at 3 and 6 h (P3, 6 h < 0.05). Apoptotic index in IV group was significantly higher than that in II group at pancreatic tail at 6 h (P6 h < 0.05). Expression level of Bax in III group was significantly higher than that in II group (pancreatic head P3 h,6 h < 0.01, pancreatic tail P3 h < 0.001). CONCLUSIONS: Compared with Octreotide in the treatment of SAP, the protective mechanisms of Baicalin include reducing the excessive inflammatory mediators’ release, inducing the pancreatic acinar cells apoptosis. PMID:21772857

  15. Nitric oxide is overproduced by peritoneal macrophages in rat taurocholate pancreatitis: the mechanism of inducible nitric oxide synthase expression.

    PubMed

    Satoh, A; Shimosegawa, T; Kimura, K; Moriizumi, S; Masamune, A; Koizumi, M; Toyota, T

    1998-11-01

    To investigate the pathobiology of severe acute pancreatitis, we studied the expression of inducible nitric oxide synthase (iNOS) in peritoneal macrophages of experimental pancreatitis. Taurocholate (TCA) pancreatitis and cerulein (CE) pancreatitis were used as models of lethal and self-limited pancreatitis, respectively, and the mechanism of iNOS expression in peritoneal macrophages was studied. Serum nitrate and nitrite (NOx) concentrations increased during the course of TCA pancreatitis, and iNOS-immunoreactivity was detected in the peritoneal macrophages 12 h after the induction of TCA pancreatitis, but these phenomena were not observed in CE pancreatitis. Despite the difference in the iNOS expression, the iNOS messenger RNA (mRNA) and the activation of nuclear factor-kappa B (NF-kappa B) were detected in the peritoneal macrophages of both pancreatitis models. The supernatant of TCA pancreatitis ascites could induce iNOS in the peritoneal macrophages of normal rats in vitro, but the peritoneal lavage fluid of CE pancreatitis rats could not. The results indicated that there may be qualitative or quantitative differences in the macrophage activation between the two types of experimental pancreatitis and suggested that the ascites of rats with lethal acute pancreatitis contains some soluble factors that activate the macrophage/monocyte system and cause an overproduction of NO by the iNOS expression.

  16. Effective peritoneal therapy of acute pancreatitis in the rat with glutaryl-trialanin-ethylamide: a novel inhibitor of pancreatic elastase.

    PubMed Central

    Fric, P; Slabý, J; Kasafírek, E; Kocna, P; Marek, J

    1992-01-01

    The six hour peritoneal lavage with glutaryl-trialanin-ethylamide, a low molecular competitive inhibitor of pancreatic elastase (IC50-8 mumol/l), effectively suppresses the evolution of taurocholate induced acute pancreatitis in the rat. The lavage alone is followed by a marked decrease of fat necrosis and amylase and lipase activity in serum. The area of pancreatic haemorrhage was significantly reduced only after the lavage solution was supplemented with Glt-Ala3-NHEt. The effect was not enhanced by a bolus injection of the inhibitor before starting the lavage. The combination of Glt-Ala3-NHEt with aprotinin or nafamstate mesilate produced only marginal greater benefit. The effect of Glt-Ala3-NHEt on pancreatic haemorrhage is time and dose related even with delayed onset of the lavage. Animals treated with peritoneal lavage without Get-Ala3-NHEt lived longer than controls (p less than 0.05), but by 60 hours the survival rate of both groups was almost the same (76 v 74%). All animals lavaged with Glt-Ala3-NHEt survived 120 hours and the difference in the survival rate between this and both remaining groups was significant (100% v 76% v 74% - p less than 0.05). The results were considered favourable and preliminary clinical trials of Glt-Ala3-NHEt in subjects with acute pancreatitis justified. PMID:1377154

  17. The effect of exogenous apelin on the secretion of pancreatic juice in anaesthetized rats.

    PubMed

    Kapica, M; Jankowska, A; Antushevich, H; Pietrzak, P; Bierla, J B; Dembinski, A; Zabielski, R

    2012-02-01

    Apelin is known to stimulate cholecystokinin (CCK) and inhibit insulin release, however the mechanisms on pancreatic secretion remain unclear. The present study aimed to determine the expression of apelin and apelin receptor in the pancreas by immunofluorescence studies and the effect of exogenous apelin on the secretion of pancreatic juice in anesthetized rats. Pancreatic-biliary juice (P-BJ) was collected from Wistar rats treated with apelin (10, 20 and 50 nmol/kg b.w., boluses given every 30 min intravenously or intraduodenaly). The same apelin doses were administered to rats subjected to intraduodenal tarazapide, capsaicin or vagotomy. Pancreatic blood flow was measured by a laser doppler flowmeter. Direct effects of apelin were tested on dispersed acinar cells. Apelin receptor was expressed on acinar cells, pancreatic duct and islets cells, whereas apelin in pancreatic acini, but not in the islets. Intravenous apelin decreased P-BJ volume, protein and trypsin outputs in a dose-dependent manner. In contrast, intraduodenal apelin stimulated P-BJ secretion. Pharmacological block of mucosal CCK(1) receptor by tarazepide, vagotomy and capsaicin pretreatment abolished the effects of intravenous and intraduodenal apelin on P-BJ volume, protein and tryspin outputs. Apelin decreased the pancreatic blood flow. Apelin at 10(-6) M increased the release of amylase from non-stimulated and CCK-8-stimulated acinar cells. In conclusion, apelin can affect the exocrine pancreas through a complex mechanism involving local blood flow regulation and is driven by vagal nerves.

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

    SciTech Connect

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

    2006-08-18

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

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

    PubMed Central

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

    2015-01-01

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

  20. Effects of epigallocatechin gallate on diethyldithiocarbamate-induced pancreatic fibrosis in rats.

    PubMed

    Meng, Min; Li, Yan-Qing; Yan, Ming-Xian; Kou, Yi; Ren, Hong-Bo

    2007-06-01

    Epigallocatechin gallate (EGCG), a major component of green tea extracts, is known to have anti-fibrotic properties in many organs. The aim of present study was to investigate effects of EGCG on rat pancreatic fibrosis induced by diethyldithiocarbamate (DDC). Oral gavages of different dose of EGCG (50, 100 and 200 mg/kg daily for 8 weeks) ameliorated histological changes and significantly suppressed collagen deposition in a dose-dependent manner. Meanwhile, administration of EGCG inhibited overexpression of TGF-beta1 and alpha-smooth muscle actin (a symbol of activation of pancreatic stellate cells). Moreover, EGCG has a potent influence on expression of Smads (downstream transcription factor of TGF-beta1). EGCG suppressed the expression of Smad3 and enhanced the expression of Smad7. In conclusion, our results demonstrated that EGCG attenuated rat pancreatic fibrosis induced by DDC and therefore may be an anti-fibrogenic candidate in the pancreatic fibrosis.

  1. Pancreatitis

    MedlinePlus

    ... removal is sometimes performed along with a sphincterotomy. Stent placement. Using the endoscope, the doctor places a ... a narrowed pancreatic or bile duct. A temporary stent may be placed for a few months to ...

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

    PubMed

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

    2016-01-01

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

  3. Hyperlipidemia intensifies cerulein-induced acute pancreatitis associated with activation of protein kinase C in rats

    PubMed Central

    Wang, Ya-Jun; Sun, Jia-Bang; Li, Fei; Zhang, Shu-Wen

    2006-01-01

    AIM: To investigate the effects of hyperlipidemia on acute pancreatitis (AP) and the possible mechanisms. METHODS: Rat models of hyperlipidemia and AP were established by Triton WR1339 and cerulein respectively. Human albumin was used to treat AP complicated by hyperlipidemia. In each group, we compared the histological score, volume of ascites, ratio of pancreatic wet/dry weight, serum amylase (AMY) and pancreatic acinar cell apoptosis. The level of protein kinase C (PKC) membrane translocation in pancreatic tissue was detected by Western blot. RESULTS: In the hyperlipidemia model established by Triton WR1339, triglyceride (TG) increased remarkably and reached its peak 6 h after injection, and most rats developed mild acute pancreatitis. Histological score, volume of ascites, ratio of wet/dry weight and serum AMY in AP animals with hyperlipidemia were obviously higher than those in AP animals (P < 0.05) and decreased after albumin therapy but not significantly (P > 0.05). Apoptotic cells detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) increased in AP animals with hyperlipidemia and did not change distinctly after albumin therapy. PKC membrane translocation level increased in AP animals with hyperlipidemia and decreased remarkably after albumin therapy (P < 0.05). CONCLUSION: Hyperlipidemia may induce AP or intensify pancreatic injury. Albumin therapy can not alleviate pancreatic lesion effectively. PKC activation may be one mechanism by which AP is intensified by hyperlipidemia. PMID:16718817

  4. [The effect of semax and mexidol on the course of acute pancreatitis in rats].

    PubMed

    Ivanov, Iu V; Iasnetsov, V V

    2000-01-01

    The effect of semax and mexidol on the course of acute pancreatitis in rats was studied in comparison with the action of contrical, fluorouracil, and dibunol. It was established that a single intraductal or intraperitoneal administration of semax or mexidol markedly reduces the loss of experimental animals (to 10-13%), decreases hyperfermentemia, lipid peroxidation activation, and vascular permeability, improves microcirculation, and accelerates healing of the damaged pancreatic zones by substitutional repair of pancreatic acini not accompanied by coarse fibrous changes in the parenchyma. Upon the intraductal administration, semax and mexidol were more effective than contrical, fluorouracil, and dibunol.

  5. Functional Characterization of HCN Channels in Rat Pancreatic β Cells

    PubMed Central

    Zhang, Yi; Liu, Yunfeng; Qu, Jihong; Hardy, Alexandre; Zhang, Nina; Diao, Jingyu; Strijbos, Paul J.; Tsushima, Robert; Robinson, Richard B.; Gaisano, Herbert Y.; Wang, Qinghua; Wheeler, Michael B.

    2010-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate pacemaker activity in some cardiac cells and neurons. In the present study, we have identified the presence of HCN channels in pancreatic β-cells. We then examined the functional characterization of these channels in β-cells via modulating HCN channel activity genetically and pharmacologically. Voltage-clamp experiments showed that over-expression of HCN2 in rat β-cells significantly increased HCN current (Ih), whereas expression of dominant-negative HCN2 (HCN2-AYA) completely suppressed endogenous Ih. Compared to control β-cells, over-expression of Ih increased insulin secretion at 2.8 mmol/l glucose. However, suppression of Ih did not affect insulin secretion at both 2.8 mmol/l and 11.1 mmol/l glucose. Current-clamp measurements revealed that HCN2 over-expression significantly reduced β-cell membrane input resistance (Rin), and resulted in a less hyperpolarizing membrane response to the currents injected into the cell. Conversely, dominant negative HCN2-AYA expression led to a substantial increase of Rin, which was associated with a more hyperpolarizing membrane response to the currents injected. Remarkably, under low extracellular potassium conditions (2.5mmol/l K+), suppression of Ih resulted in increased membrane hyperpolarization and decreased insulin secretion. We conclude that Ih in β-cells possess the potential to modulate β-cell membrane potential and insulin secretion under hypokalemic conditions. PMID:19654142

  6. mTORC1 pathway mediates beta cell compensatory proliferation in 60 % partial-pancreatectomy mice.

    PubMed

    Li, Wenyi; Zhang, Hongli; Nie, Aifang; Ni, Qicheng; Li, Fengying; Ning, Guang; Li, Xiaoying; Gu, Yanyun; Wang, Qidi

    2016-07-01

    Beta cell replication is the major component for maintenance of beta cell mass in adult rodents; however, little is known about what is the earliest signals that initiate rodent beta cell proliferation. The mTORC1 pathway integrates signals from growth factors and nutrients and regulates cell growth and survival. Here, we used normoglycemic 60 % partial-pancreatectomy (60 % Px) mouse model to determine whether mTORC1 pathway was required for compensatory beta cell proliferation. C57BL/6 J male mice were subjected to 60 % Px or sham operation, and subsequently treated with either rapamycin or vehicle for 7 days. Metabolic profile, pancreatic beta cell mass, and proliferation were examined, and expression levels of cell cycle regulators were determined. Beta cell proliferation was increased by 2.5-fold, and mTORC1 signaling was activated in islets post-Px. Rapamycin treatment impaired glucose tolerance and glucose stimulating insulin secretion in 60 % Px mice, but did not affect their insulin sensitivity in peripheral tissue. Rapamycin inhibited mTORC1 activity in beta cells, suppressed compensatory beta cell proliferation and growth, and reduced beta cell mass and insulin content in 60 % Px mice. Px caused an increase of the cyclin D2 at protein level and promoted cyclin D2 nuclear localization in an mTOR-dependent manner. Disrupting mTORC1 signaling suppressed cell proliferation and simultaneously diminished cyclin D2 protein abundance in RINm5F cells. Our data demonstrated that mTORC1 plays an essential role in beta cell adaption to significant beta cell mass loss in 60 % Px model and in early compensatory beta cell proliferation via cyclin D2 pathway.

  7. Peptide YY ameliorates cerulein-induced pancreatic injury in the rat.

    PubMed

    Tito, J M; Rudnicki, M; Jones, D H; Alpern, H D; Gold, M S

    1993-06-01

    Peptide YY (PYY), a known inhibitor of both pancreatic secretion and the release of cholecystokinin (CCK), may play a role in the pathophysiology of acute pancreatitis (AP). Supramaximal stimulation of the pancreas with CCK, or its analogue cerulein, induces edematous AP. We previously documented significant decreases in plasma PYY in sodium taurocholate-induced AP in the anesthetized pig, with exogenous PYY suppressing plasma amylase activity. We hypothesized that PYY may ameliorate cerulein-induced pancreatic injury in a conscious animal model. Thirty-two male Sprague-Dawley rats underwent chronic cannulation of the jugular vein and carotid artery for drug infusion and blood sampling. The animals were allowed to recover from anesthesia for a minimum of 16 hours, after which they were randomized to one of four (n = 8) treatment groups (cerulein 10 micrograms/kg/h, PYY 400 pmol/kg/h, cerulein+PYY, and control-saline 2 mL/kg/h). All treatments were administered by intravenous infusion over the first 6 hours of the experiment. Blood samples were taken prior to infusion and at 1, 3, 6, 9, and 24 hours into the study; the rats were then killed and the pancreata removed for weighing and histologic examination. All pancreatic specimens were graded in a blinded fashion for vacuolization, edema, inflammation, and necrosis. The mean basal plasma amylase level for all animals was 1,171 +/- 100 U/L and was not significantly different between groups. Infusion of cerulein resulted in significant increases in plasma amylase levels at 3, 6, 9, and 24 hours (4,827 +/- 1,022 U/L at 24 hours). In the group receiving both cerulein and PYY, the hyperamylasemia was attenuated with a return to basal values at 24 hours (1,206 +/- 103 U/L). There was significant pancreatic weight gain (1.99 +/- 0.07 g versus 1.03 +/- 0.07 g) and a worsened histologic picture in cerulein-treated animals compared with control animals (worsened edema, necrosis, and vacuolization). The addition of PYY to

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

    SciTech Connect

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

    2012-04-20

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

  9. Spatial and temporal differences of HMGB1 expression in the pancreas of rats with acute pancreatitis

    PubMed Central

    Yu, Can; Huang, Lihua; Li, Xia; Zhu, Hongwei; Li, Zhiqiang; Yu, Xiao

    2015-01-01

    We aimed to investigate the spatial and temporal differences in expression between HMGB1 and early-stage inflammatory cytokines (IL-1, IL-6 and TNF-α) in pancreas tissue in rats with acute pancreatitis. SD rats (BW 350 ± 30 g, n = 48) were randomly divided into the experimental group (n = 36) which were injected with 5% sodium taurocholate into the bilipancreatic duct retrogradely to produce acute necrotic pancreatitis (ANP) rat models, and the sham-operated (SO) group (n = 12) injected with equal dose of saline. The rats were sacrificed at different time points at 0 h, 3 h, 6 h, 12 h, and 24 h post modeling, respectively. The peripheral blood amylase and different inflammatory factors in ANP rats at different time points were detected by ELISA, and the expression of HMGB1 in the pancreatic tissue was detected by immunohistochemistry, Western blot and Q-PCR methods. Results showed that the serum amylase in the ANP model rats was significantly higher than the sham-operated group (P < 0.05). The early inflammatory factors (IL-1, TNF-α and IL-6) increased quickly at 3 h after the model induction, reached the peak level at 6 h (higher than SO group, P < 0.05), then decreased at 12 h, and at 24 h the levels were lower than those at 12 h (P < 0.05). The HMGB1 level in the pancreatitis tissue did not change significantly at 3 h and 6 h (P > 0.05), however, it increased remarkably at 12 h, and maintained up to 24 h (P > 0.05). As a late inflammatory factor, the expression of HMGB1 in acute pancreatitis was obviously later than the early inflammatory factors IL-1, TNF-α and IL-6. HMGB1 may play a key role in maintaining the development of the acute pancreatitis. PMID:26261580

  10. Spatial and temporal differences of HMGB1 expression in the pancreas of rats with acute pancreatitis.

    PubMed

    Yu, Can; Huang, Lihua; Li, Xia; Zhu, Hongwei; Li, Zhiqiang; Yu, Xiao

    2015-01-01

    We aimed to investigate the spatial and temporal differences in expression between HMGB1 and early-stage inflammatory cytokines (IL-1, IL-6 and TNF-α) in pancreas tissue in rats with acute pancreatitis. SD rats (BW 350 ± 30 g, n = 48) were randomly divided into the experimental group (n = 36) which were injected with 5% sodium taurocholate into the bilipancreatic duct retrogradely to produce acute necrotic pancreatitis (ANP) rat models, and the sham-operated (SO) group (n = 12) injected with equal dose of saline. The rats were sacrificed at different time points at 0 h, 3 h, 6 h, 12 h, and 24 h post modeling, respectively. The peripheral blood amylase and different inflammatory factors in ANP rats at different time points were detected by ELISA, and the expression of HMGB1 in the pancreatic tissue was detected by immunohistochemistry, Western blot and Q-PCR methods. Results showed that the serum amylase in the ANP model rats was significantly higher than the sham-operated group (P < 0.05). The early inflammatory factors (IL-1, TNF-α and IL-6) increased quickly at 3 h after the model induction, reached the peak level at 6 h (higher than SO group, P < 0.05), then decreased at 12 h, and at 24 h the levels were lower than those at 12 h (P < 0.05). The HMGB1 level in the pancreatitis tissue did not change significantly at 3 h and 6 h (P > 0.05), however, it increased remarkably at 12 h, and maintained up to 24 h (P > 0.05). As a late inflammatory factor, the expression of HMGB1 in acute pancreatitis was obviously later than the early inflammatory factors IL-1, TNF-α and IL-6. HMGB1 may play a key role in maintaining the development of the acute pancreatitis.

  11. Pancreatic secretory and trophic response to caerulein in rats: effect of proglumide and lorglumide.

    PubMed

    Varga, G; Papp, M; Scarpignato, C

    1989-01-01

    The effect of proglumide and lorglumide, two CCK-receptor antagonists, on caerulein-induced pancreatic secretion and growth was studied in the rat. In anaesthetised animals, caerulein (1 microgram/kg) significantly increased the volume of pancreatic juice and protein output. Lorglumide (5 and 10 mg/kg), administered intraperitoneally 15 min before stimulation, reduced peptide-induced pancreatic exocrine secretion. By contrast, proglumide (100 and 400 mg/kg) was completely ineffective. In experiments dealing with the trophic effect of caerulein, both drugs were administered alone or combined with the peptide (1 microgram/kg) 3 times daily for 5 d. Saline-treated rats served as controls. At the end of the experiment, rats were sacrificed, and growth and composition of pancreatic tissue were determined. Pretreatment of the animals with either proglumide or lorglumide did not affect pancreatic size and composition. Caerulein increased the weight of the pancreas, the total pancreatic protein, trypsin, amylase, and DNA content. After pretreatment with proglumide, all these parameters were not significantly different from those obtained with caerulein alone. In contrast, when lorglumide was given together with caerulein, it significantly reduced caerulein-induced pancreatic growth and decreased enzymatic protein content of the gland. These results show that lorglumide is a much more potent and effective CCK-receptor antagonist than proglumide. Its ability to antagonize the pancreatic secretory and trophic action of a CCK-analogue (i.e. caerulein) supports the view that these physiological actions of CCK are mediated through an interaction of the hormone with specific receptors.

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

    SciTech Connect

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

    2009-02-15

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

  13. Thoracic duct ligation in the rat attenuates lung injuries in acute pancreatitis.

    PubMed

    Zhang, D; Tsui, N; Li, Y; Wang, F

    2013-09-01

    In acute pancreatitis (AP), inflammatory cells and products disseminated in abdominal lymph and blood induce systemic inflammation. Interruption of abdominal lymph flow, and thereby reduction of lymphatic dissemination, could alter the course of the disease. Therefore, we investigated whether thoracic duct ligation (TDL) in a rat model of cerulein-induced AP results in reduced lung damage as a marker for reduction of systemic dissemination through the lymphatic system. Thirty-four male rats were assigned to TDL (TDL-rats, n=8), AP (AP-rats, n=8), TDL+AP (TDL+AP-rats, n=9) or sham TDL (Ctr-rats, n=9) groups. TDL and sham TDL were established first. Two days later, AP was induced in AP- and TDL+AP-rats by a series of subcutaneous injections of cerulein. Vehicle was injected in the same manner in Ctr- and TDL-rats as controls. Rats were sacrificed six hours after the end of the serial injections. Histological examination showed that AP-induced damage to the pancreas and ileum were similar in AP- and TDL+AP-rats whereas lung damage was less severe in TDL+AP-rats than in AP-rats. Assays demonstrated that: hepatic and pulmonary myeloperoxidase activities were increased in AP-rats but not in the TDL+AP-rats; more Il-6 was found in AP-rat than TDL+AP-rat lungs; and lung-lavage fluid from AP-rats yielded more angiopoietin-2 than TDL+AP-rats. In conclusion, prior TDL in the rat attenuates lung damage in acute pancreatitis.

  14. Protective effects of daphnetin on sodium taurocholate‑induced severe acute pancreatitis in rats.

    PubMed

    Liu, Zhi-Yong; Liu, Jiao; Zhao, Kai-Liang; Wang, Li-Kun; Shi, Qiao; Zuo, Teng; Liu, Tian-Yi; Zhao, Liang; Wang, Wei-Xing

    2014-05-01

    Severe acute pancreatitis (SAP) is the sudden onset of pancreatic inflammation, which is characterized by edema, acinar cell necrosis, hemorrhage and severe inflammation of the pancreas and is associated with a high mortality rate. Daphnetin has been shown to alleviate organ injury in a variety of preclinical animal models of coagulation disorders. The aim of the present study was to investigate the protective effects of daphnetin on severe acute pancreatitis in a rat model. Severe acute pancreatitis in the rat model was induced by retrograde infusion of 5% sodium taurocholate (1 ml/kg) into the bile-pancreatic duct. Daphnetin (4 mg/kg) was administered intraperitoneally at 30 min prior to the infusion of sodium taurocholate. The severity of pancreatitis was evaluated by various analyses of serum amylase and lipase, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels, myeloperoxidase (MPO) activity and malondialdehyde (MDA) content, as well as by histological grading. The levels of TNF-α and IL-1β in the serum were measured by ELISA. The results revealed that the daphnetin-treated SAP rat group (SAP-D) exhibited a lower pathological score of the pancreas compared with the SAP group (SAP). Further analyses demonstrated that the SAP-D group had lower levels of serum amylase, lipase and pro-inflammatory cytokines, including TNF-α and IL-1β, and a decreased MPO activity and MDA content 3, 6 and 12 h subsequent to the infusion of sodium taurocholate compared with the SAP group (SAP). These findings indicated that daphnetin exerted a protective function in the SAP rat model. Therefore, daphnetin may be considered as a potential compound for the therapy and prevention of acute pancreatitis.

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

    PubMed

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

    2015-01-01

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

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

    PubMed

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

    2016-10-01

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

  17. Imaging Beta Cell Regeneration and Interactions with Islet Vasculature in Transparent Adult Zebrafish

    PubMed Central

    Moss, Larry G.; Caplan, Tanner V.

    2013-01-01

    Abstract Blood vessel networks provide nutrients and gaseous exchange that are essential for functions. Pancreatic islet capillaries deliver oxygen to endocrine cells while transporting hormones to organs and peripheral locations throughout the body. We have developed a zebrafish diabetes model in which adult islets can be followed in vivo during beta cell regeneration while calibrating changes in beta cell mass and fasting blood glucose levels. After genetic ablation, beta cells are initially dysfunctional or dying, and blood glucose levels increase fourfold. During a 2-week period, hyperglycemia eventually normalizes as beta cell mass regenerates. We show that mCherry-fluorescent, insulin-positive beta cells re-emerge in close contact with the vascular endothelium. Alterations in the dense vascular network of zebrafish islets were visualized by the expression of green fluorescent protein (GFP) in endothelial cells derived from the Fli transcription factor promoter. The rapid destruction and regeneration of beta cell mass was evaluated in the same animal over time, providing a functional model for investigating the interactions of islet cell types with vascular cells as well as the consequences of hyperglycemia on other tissues. Regenerating adult zebrafish can be utilized as vertebrate, metabolically active models for generating new insights into treatments for type 2 diabetes. PMID:23682836

  18. Does Disruption of Circadian Rhythms Contribute to Beta-Cell Failure in Type 2 Diabetes?

    PubMed Central

    Rakshit, Kuntol; Thomas, Anthony P.

    2014-01-01

    Type 2 diabetes mellitus (T2DM) is a complex metabolic disease characterized by the loss of beta-cell secretory function and mass. The pathophysiology of beta-cell failure in T2DM involves a complex interaction between genetic susceptibilities and environmental risk factors. One environmental condition that is gaining greater appreciation as a risk factor for T2DM is the disruption of circadian rhythms (eg, shift-work and sleep loss). In recent years, circadian disruption has become increasingly prevalent in modern societies and consistently shown to augment T2DM susceptibility (partly mediated through its effects on pancreatic beta-cells). Since beta-cell failure is essential for development of T2DM, we will review current work from epidemiologic, clinical, and animal studies designed to gain insights into the molecular and physiological mechanisms underlying the predisposition to beta-cell failure associated with circadian disruption. Elucidating the role of circadian clocks in regulating beta-cell health will add to our understanding of T2DM pathophysiology and may contribute to the development of novel therapeutic and preventative approaches. PMID:24532160

  19. A serial histologic study of the development and progression of acute pancreatitis in the rat.

    PubMed Central

    Rao, S. S.; Watt, I. A.; Donaldson, L. A.; Crocket, A.; Joffe, S. N.

    1981-01-01

    This study was undertaken for the purpose of a serial investigation of the development and progression of the light-microscopic changes of acute pancreatitis and histologic criteria for evaluating pancreatitis. Acute pancreatitis, similar to that found in man, was induced in rats with the use of a closed duodenal loop technique (n = 36). Control rats underwent a laparotomy with mobilization of the duodenum (n = 12). Animals were killed every 2 hours for 24 hours, and a detailed and independent histologic evaluation was made of each. Focal acinar necrosis proceeding to a vasculitis appeared within 2--4 hours before the infiltration of inflammatory cells. Thereafter, the extent of acinar necrosis closely reflected the vasculitis with the later development of the acute inflammation. By the sixteenth hour, these changes were graded as moderate pancreatitis, and by 24 hours the process represented severe hemorrhagic pancreatitis. Vascular changes and acinar necrosis preceded the inflammatory cell infiltrate. The pancreatitis has been quantitated into minimal, moderate, or severe by assessing the severity of edema, acute inflammatory infiltrate, and changes in the vessels, ducts, and acini. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 PMID:7223862

  20. Protective Effects of Proanthocyanidin on Cerulein-induced Acute Pancreatic Inflammation in Rats

    PubMed Central

    Akyuz, Cebrail; Sehirli, Ahmet Ozer; Topaloglu, Umit; Ogunc, Ayliz Velioglu; Cetinel, Sule; Sener, Goksel

    2009-01-01

    Background The aim of this study was to assess the possible protective effect of proanthocyanidin against cerulein-induced acute pancreatic inflammation (AP) and oxidative injury. Methods Sprague-Dawley rats were pretreated with proanthocyanidine (100 mg/kg, orally) or saline 15 min before cerulein was given by 20 µg/kg subcutaneously at 1-h intervals within 4 hours. Six hours after cerulein or saline injections, the animals were killed by decapitation. Blood samples were collected to analyze amylase, lipase, and proinflammatory cytokines (TNF-α and IL-1b). Pancreas tissues were taken for the determination of tissue glutathione (GSH) and malondialdehyde (MDA) levels, Na+, K+-ATPase and myeloperoxidase (MPO) activities. Formation of reactive oxygen species in pancreatic tissue samples was monitored by using chemiluminescence (CL) technique with luminol and lucigenin probes, while the extent of tissue injury was analyzed microscopically. Results Acute pancreatitis caused a significant decrease in tissue GSH level and Na+, K+-ATPase activity, which was accompanied with significant increases in the pancreatic MDA, luminol and lucigenin chemiluminescences (CL) levels and MPO activity. Similarly TNF-α and IL-1β levels were elevated in the pancreatic group as compared to control group. On the other hand, proanthocyanidin treatment reversed all these biochemical indices, as well as histopathological alterations that were induced by cerulein. Conclusions Proanthocyanidine can ameliorate pancreatic injury induced by cerulein in rats, this result suggests that proanthocyanidin may have utility in treating acute pancreatititis. PMID:27956946

  1. Dihydro-Resveratrol Ameliorates Lung Injury in Rats with Cerulein-Induced Acute Pancreatitis.

    PubMed

    Lin, Ze-Si; Ku, Chuen Fai; Guan, Yi-Fu; Xiao, Hai-Tao; Shi, Xiao-Ke; Wang, Hong-Qi; Bian, Zhao-Xiang; Tsang, Siu Wai; Zhang, Hong-Jie

    2016-04-01

    Acute pancreatitis is an inflammatory process originated in the pancreas; however, it often leads to systemic complications that affect distant organs. Acute respiratory distress syndrome is indeed the predominant cause of death in patients with severe acute pancreatitis. In this study, we aimed to delineate the ameliorative effect of dihydro-resveratrol, a prominent analog of trans-resveratrol, against acute pancreatitis-associated lung injury and the underlying molecular actions. Acute pancreatitis was induced in rats with repetitive injections of cerulein (50 µg/kg/h) and a shot of lipopolysaccharide (7.5 mg/kg). By means of histological examination and biochemical assays, the severity of lung injury was assessed in the aspects of tissue damages, myeloperoxidase activity, and levels of pro-inflammatory cytokines. When treated with dihydro-resveratrol, pulmonary architectural distortion, hemorrhage, interstitial edema, and alveolar thickening were significantly reduced in rats with acute pancreatitis. In addition, the production of pro-inflammatory cytokines and the activity of myeloperoxidase in pulmonary tissues were notably repressed. Importantly, nuclear factor-kappaB (NF-κB) activation was attenuated. This study is the first to report the oral administration of dihydro-resveratrol ameliorated acute pancreatitis-associated lung injury via an inhibitory modulation of pro-inflammatory response, which was associated with a suppression of the NF-κB signaling pathway.

  2. α-Lipoic acid protects against cholecystokinin-induced acute pancreatitis in rats

    PubMed Central

    Park, Sung-Joo; Seo, Sang-Wan; Choi, Ok-Sun; Park, Cheung-Seog

    2005-01-01

    AIM: α-Lipoic acid (ALA) has been used as an antioxidant. The aim of this study was to investigate the effect of α-lipoic acid on cholecystokinin (CCK)-octapeptide induced acute pancreatitis in rats. METHODS: ALA at 1 mg/kg was intra-peritoneally injected, followed by 75 μg/kg CCK-octapeptide injected thrice subcutaneously after 1, 3, and 5 h. This whole procedure was repeated for 5 d. We checked the pancreatic weight/body weight ratio, the secretion of pro-inflammatory cytokines and the levels of lipase, amylase of serum. Repeated CCK octapeptide treatment resulted in typical laboratory and morphological changes of experimentally induced pancreatitis. RESULTS: ALA significantly decreased the pancreatic weight/body weight ratio and serum amylase and lipase in CCK octapeptide-induced acute pancreatitis. However, the secretion of IL-1β, IL-6, and TNF-α were comparable in CCK octapeptide-induced acute pancreatitis. CONCLUSION: ALA may have a protective effect against CCK octapeptide-induced acute pancreatitis. PMID:16097064

  3. Protective effect of CR 1409 (cholecystokinin antagonist) on experimental pancreatitis in rats and mice.

    PubMed

    Makovec, F; Bani, M; Cereda, R; Chistè, R; Revel, L; Rovati, L C; Setnikar, I; Rovati, L A

    1986-01-01

    CR 1409, a glutaramic acid derivative with competitive cholecystokinin-antagonistic activity, was administered IP and evaluated in comparison with proglumide (the model CCK-receptor antagonist), gabexate (protease inhibitor) and PGE2 (cytoprotective) on two different models of experimental pancreatitis. Acute pancreatitis was induced in mice by six IP injections of 50 micrograms/kg caerulein at hourly intervals. The drugs were administered 30 minutes before each caerulein administration. Blood samples and pancreata were collected 3 hours after the last caerulein injection. In the second experiment, pancreatitis was induced in rats by injecting 0.3 ml 6% sodium taurocholate interstitially into the pancreas. The drugs were administered twice, 30 minutes before and 3 hours after taurocholate. The animals were killed 6 hours after laparotomy and blood samples and pancreata were collected. CR 1409 exhibited on both pancreatitis models a protective effect in a dose range of 0.3-10 mg/kg. Proglumide exhibited a protective activity at higher doses (200-400 mg/kg). Gabexate and PGE2 were effective only in pancreatitis induced by taurocholate in a dose range of 30-60 mg/kg and 60-130 micrograms/kg respectively. These results, showing a high protective effect of CR 1409 on different models of acute pancreatitis, suggest an important role of CCK in the pathogenesis of pancreatitis.

  4. The malate-aspartate NADH shuttle member Aralar1 determines glucose metabolic fate, mitochondrial activity, and insulin secretion in beta cells.

    PubMed

    Rubi, Blanca; del Arco, Araceli; Bartley, Clarissa; Satrustegui, Jorgina; Maechler, Pierre

    2004-12-31

    The NADH shuttle system, which transports reducing equivalents from the cytosol to the mitochondria, is essential for the coupling of glucose metabolism to insulin secretion in pancreatic beta cells. Aralar1 and citrin are two isoforms of the mitochondrial aspartate/glutamate carrier, one key constituent of the malate-aspartate NADH shuttle. Here, the effects of Aralar1 overexpression in INS-1E beta cells and isolated rat islets were investigated for the first time. We prepared a recombinant adenovirus encoding for human Aralar1 (AdCA-Aralar1), tagged with the small FLAG epitope. Transduction of INS-1E cells and isolated rat islets with AdCA-Aralar1 increased aralar1 protein levels and immunostaining revealed mitochondrial localization. Compared with control INS-1E cells, overexpression of Aralar1 potentiated metabolism secretion coupling stimulated by 15 mm glucose. In particular, there was an increase of NAD(P)H generation, of mitochondrial membrane hyperpolarization, ATP levels, glucose oxidation, and insulin secretion (+45%, p < 0.01). Remarkably, this was accompanied by reduced lactate production. Rat islets overexpressing Aralar1 secreted more insulin at 16.7 mm glucose (+65%, p < 0.05) compared with controls. These results show that aspartate-glutamate carrier capacity limits glucose-stimulated insulin secretion and that Aralar1 overexpression enhances mitochondrial metabolism.

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

    PubMed Central

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

    2009-01-01

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

  6. Different antagonist binding properties of rat pancreatic and cardiac muscarinic receptors

    SciTech Connect

    Waelbroeck, M.; Camus, J.; Winand, J.; Christophe, J.

    1987-11-09

    The antagonist binding properties of rat pancreatic and cardiac muscarinic receptors were compared. In both tissues pirenzepine (PZ) had a low affinity for muscarinic receptors labelled by (/sup 3/H)N-methylscopolamine ((/sup 3/)NMS) (K/sub D/ values of 140 and 280nM, respectively, in pancreatic and cardiac homogenates). The binding properties of pancreatic and cardiac receptors were, however, markedly different. This was indicated by different affinities for dicyclomine, (11-(/(2-((diethylamino)-methyl)-1-piperidinyl/acetyl)-5, 11-dihydro-6H-pyrido(2,3-b)(1,4) benzodiazepin-6-on)(AFDX-116), 4-diphenylacetoxy-N-methyl-piperidine methobromide (4-DAMP) and hexahydrosiladifenidol (HHSiD). Pancreatic and cardiac muscarinic receptros also showed different (/sup 3/H)NMS association and dissociation rates. These results support the concept of M2 receptor subtypes have different binding kinetic properties. 20 references, 3 figures, 1 table.

  7. [Mesenchymal stromal cells transplantation in acute and chronic pancreatitis in rats].

    PubMed

    Lazebnik, L B; Trubitsyna, I E; Agafonov, M A; Kniazev, O V; Liundup, A V

    2011-01-01

    Before using MSC transplantation in the clinic to conduct preclinical studies MSCs to animals with acute and chronic pancreatitis. Work out the timing and dose of MSCs. The rationale of MSCs transplantation for the regeneration of damaged pancreatic tissue. The essence of the experiments is to establish the existence of common pathogenetic mechanisms for the development of pathological processes and sanogenesis toxic damage of pancreatic tissue. The study was work out in the rat model of acute and chronic pancreatitis, to explore beneficial and adverse effects of allogeneic stem cells for regenerative-reduction processes. For cell transplantation using allogenic stromal cell fraction of bone marrow, the cell suspension was injected at a dose of 2 x 10(6) and 5 x 10(6) cells.

  8. Action of a new cholinergic agonist, aclatonium napadisilate, on isolated rat pancreatic acini

    SciTech Connect

    Fujii, M.; Okabayashi, Y.; Nakamura, T.; Tani, S.; Fujisawa, T.; Otsuki, M. )

    1990-07-01

    The effect of aclatonium napadisilate, a newly synthesized choline ester, on pancreatic exocrine function was compared with that of the muscarinic agonist carbamylcholine in isolated rat pancreatic acini. Both compounds increased amylase release and {sup 45}Ca{sup 2+} efflux in a dose-dependent fashion, and similarly decreased the binding of (N-methyl-{sup 3}H)scopolamine to isolated rat pancreatic acini. While aclatonium napadisilate was 20-30 times less potent than carbamylcholine in stimulations of amylase release and {sup 45}Ca{sup 2+} efflux, the potency of aclatonium napadisilate in inhibiting (N-methyl-{sup 3}H)scopolamine binding was nearly the same as that of carbamylcholine. These results indicate that aclatonium napadisilate stimulates pancreatic exocrine secretion via muscarinic receptors and Ca{sup 2+} mobilization, and its intrinsic activity is less than carbamylcholine in the isolated rat pancreatic acini. Since aclatonium napadisilate is known to increase motility and peristalsis of the gastrointestinal tract, stimulatory effects of aclatonium napadisilate, shown in the present study, on digestive enzyme secretion from the pancreas may provide additional benefit of aclatonium napadisilate in the treatment of various gastrointestinal disorders.

  9. beta-cell apoptosis and defense mechanisms: lessons from type 1 diabetes.

    PubMed

    Eizirik, D L; Darville, M I

    2001-02-01

    Increased evidence suggests that apoptosis is the main mode of beta-cell death in early type 1 diabetes. Cytokines mediate beta-cell apoptosis, and in this article, we discuss some of the cytokine-modified genes that may contribute to beta-cell survival or death. The gene encoding for the inducible form of nitric oxide synthase is induced by interleukin (IL)-1beta or IL-1beta plus gamma-interferon in rodent and human islets, respectively. This leads to nitric oxide (NO) formation, which contributes to a major extent to beta-cell necrosis and to a minor extent to the process of beta-cell apoptosis. The main mode of cell death induced by cytokines in human beta-cells is apoptosis, whereas cytokines lead to both necrosis and apoptosis in rat and mouse beta-cells. It is suggested that the necrotic component in rodent islets is due to NO-induced mitochondrial impairment and consequent decreased ATP production. Human islets, possessing better antioxidant defenses, are able to preserve glucose oxidation and ATP production, and can thus complete the apoptotic program after the death signal delivered by cytokines. We propose that this death signal results from cytokine-induced parallel and/or sequential changes in the expression of multiple proapoptotic and prosurvival genes. The identity of these "gene modules" and of the transcription factors regulating them remains to be established.

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

    PubMed

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

    2004-12-01

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

  11. Tissue Pharmacology of Da-Cheng-Qi Decoction in Experimental Acute Pancreatitis in Rats

    PubMed Central

    Zhao, Xianlin; Zhang, Yumei; Li, Juan; Wan, Meihua; Zhu, Shifeng; Guo, Hui; Xiang, Jin; Thrower, Edwin C.; Tang, Wenfu

    2015-01-01

    Objectives. The Chinese herbal medicine Da-Cheng-Qi Decoction (DCQD) can ameliorate the severity of acute pancreatitis (AP). However, the potential pharmacological mechanism remains unclear. This study explored the potential effective components and the pharmacokinetic characteristics of DCQD in target tissue in experimental acute pancreatitis in rats. Methods. Acute pancreatitis-like symptoms were first induced in rats and then they were given different doses of DCQD (6 g/kg, 12 g/kg, and 24 g/kg body weight) orally. Tissue drug concentration, tissue pathological score, and inflammatory mediators in pancreas, intestine, and lung tissues of rats were examined after 24 hours, respectively. Results. Major components of DCQD could be found in target tissues and their concentrations increased in conjunction with the intake dose of DCQD. The high-dose compounds showed maximal effect on altering levels of anti-inflammatory (interleukin-4 and interleukin-10) and proinflammatory markers (tumor necrosis factor α and interleukin-6) and ameliorating the pathological damage in target tissues (P < 0.05). Conclusions. DCQD could alleviate pancreatic, intestinal, and lung injury by altering levels of inflammatory cytokines in AP rats with tissue distribution of its components. PMID:26199633

  12. Effects of the celecoxib on the acute necrotizing pancreatitis in rats.

    PubMed

    Alhan, Etem; Kalyoncu, Nuri I; Ercin, Cengiz; Kural, Birgul Vanizor

    2004-10-01

    The investigation of the effects of the celecoxib as a cylooxygenase-2 (COX-2) inhibitor on the course of the acute necrotising pancreatitis (ANP) in rats. ANP was induced in 72 rats by standardized intraductal glycodeoxycholic acid infusion and intravenous cerulein infusion. The rats were divided into four groups (six rats in each group): Sham + saline, sham + celecoxib, ANP + saline, ANP + celecoxib. Six hours later after the ANP induction, celecoxib (10 mg/kg) or saline was given i.p. In the 12th hour, routine cardiorespiratuar, renal parameters were monitored to assess the organ function. The serum amylase, alanine amino transferase (ALT), interleukin 6 (IL-6), lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, the serum concentration of the urea, the tissue activity of myeloperoxidase (MPO) and malondialdehyde (MDA) in pancreas and lungs were measured. The pancreas histology was examined. In the second part of the study, 48 rats were studied in four groups similar to the first part. Survival of all the rats after the induction of ANP was observed for 24 h. The induction of the pancreatitis increased the mortality from 0/12, in the sham groups to 4/12 (30%) in the acute pancreatitis with saline group, 5/12 (42%) in the acute pancreatitis with celecoxib group respectively, heart rate, the serum activities of amylase, ALT, the tissue activities of MPO, MDA in the pancreas and lung, and LDH in BAL fluid, the serum concentration of the urea and IL-6, the degree of the pancreatic damage and decreased the blood pressure, the urine production, pO(2) and the serum concentration of calcium. The use of celecoxib did not alter these changes except the serum IL-6 concentration, urine production and MPO, MDA activities in the tissue of the lungs and pancreas. Serum urea concentration and pancreatic damage in ANP + celecoxib group were insignificantly lesser than ANP + saline group. Whereas treatment with celecoxib improves lung and renal functions, the

  13. [Effect of KSG-504, a new CCK-A-receptor antagonist, on experimental acute pancreatitis in rats and mice].

    PubMed

    Kobayashi, M; Shinagawa, K; Sugiura, M; Nagasawa, T; Akahane, M; Ajisawa, Y

    1996-04-01

    We investigated the protective and/or therapeutic effects of a new cholecystokinin receptor antagonist, KSG-504, on different types of experimental pancreatitis in the rat and mouse. The intravenous injection of KSG-504 (10, 25, 50 and 100 mg/kg) before caerulein administration to the rat inhibited the increases in plasma amylase, lipase and of pancreatic wet weight in a dose-dependent manner. The histological changes due to caerulein-induced acute pancreatitis were also decreased by KSG-504 when KSG-504 (25, 50 and 100 mg/kg) was administered after the induction of acute pancreatitis; the increases in plasma amylase, lipase and pancreatic wet weight were reduced, but the histological changes of the pancreas were not decreased significantly. In the second experiment, acute pancreatitis was induced in rats by injecting 0.3 ml of 6% sodium taurocholate into the pancreatic interstitial tissue. KSG-504 administered immediately and 1.5 hr after sodium-taurocholate injection at 100 mg/kg reduced the increases of pancreatic enzymes in the plasma, pancreatic wet weight and ascites. Moreover, KSG-504 (50 and 100 mg/kg, i.v., x 2) mitigated the histological changes of taurocholate-induced acute pancreatitis. Another type of acute pancreatitis was induced in mice by dl-ethionine (0.5 g/kg, p.o., x 4) and a choline-deficient diet. KSG-504 (10, 30 and 100 mg/kg) was subcutaneously administered five times every 12 hr during the experiment. KSG-504 elongated the survival of mice in a dose-dependent manner. These findings suggest that KSG-504 has potent protective and/or therapeutic effects against acute pancreatitis and that cholecystokinin may be involved in the development of pancreatitis.

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

    SciTech Connect

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

    2006-11-01

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

  15. Glucose enhances collectrin protein expression in insulin-producing MIN6 {beta} cells

    SciTech Connect

    Saisho, Kenji; Fukuhara, Atsunori; Yasuda, Tomoko; Sato, Yoshifumi; Fukui, Kenji; Iwahashi, Hiromi; Imagawa, Akihisa; Hatta, Mitsutoki; Shimomura, Iichiro; Yamagata, Kazuya

    2009-11-06

    Collectrin is a novel target gene of hepatocyte nuclear factor-1{alpha} in pancreatic {beta}-cells and controls insulin exocytosis. Although glucose is known to stimulate the expression of genes of the insulin secretory pathway, there is no information on how glucose regulates collectrin expression. We investigated the effects of glucose on the expression of collectrin in MIN6 {beta}-cell line. Glucose, in a dose-dependent manner, increased collectrin protein levels without changing collectrin mRNA levels and protein stability, indicating that glucose stimulation of collectrin protein expression is primarily mediated at a translational level. Although mannose and pyruvate also increased collectrin protein expression level, neither 2-deoxyglucose, mitochondrial fuels leucine and glutamate, sulphonylurea nor Ca{sup 2+} channel blockers, mimicked the effects of glucose. These data indicate the involvement of mitochondrial TCA cycle intermediates, distal to pyruvate, in the regulation of collectrin protein expression in {beta}-cells.

  16. The beneficial effects of pentoxifylline on caerulein-induced acute pancreatitis in rats.

    PubMed

    Gül, Mehmet; Eşrefoğlu, Mukaddes; Oztürk, Feral; Ateş, Burhan; Otlu, Ali

    2009-03-01

    In this study we aimed to investigate the effect of pentoxifylline on caerulein-induced acute pancreatitis (AP) by detecting oxidative stress markers and performing histopathological examination. Twenty-one adult female Sprague-Dawley rats were divided into three groups as follows: control, caerulein, and caerulein + pentoxifylline groups. Pancreatic tissues of rats from all groups were removed for light and electron microscopic examination and determination of oxidative stress markers. Pancreatic oxidative stress markers were evaluated by the measurements of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and total glutathione (GSH). Serum amylase and lipase levels were determined spectrophotometrically. The pancreatic damage score was significantly increased (P < 0.005) in the caerulein group, whereas it was decreased (P < 0.05) in the caerulein+ with pentoxifylline group. MDA levels, CAT, SOD, GPx, and GSH activities were significantly altered (P < 0.05, P < 0.005) in the caerulein group and indicated increased oxidative stress. Oxidative stress markers were normalized with pentoxifylline administration. Caerulein administration resulted in significant increase (P < 0.05) in amylase and lipase levels; pentoxifylline reduced the levels of these enzymes. Pentoxifylline is potentially capable of limiting pancreatic damage produced during AP by restoring the fine structure of acinar cells and tissue antioxidant enzyme activities. We concluded that pentoxifylline may have beneficial effects in the treatment of caerulein-induced AP.

  17. [Hydroelactic and ecbolic of piprozoline on basal bile-pancreatic secretion in rats].

    PubMed

    Tiscornia, O M; Cresta, M A; Tumilasci, O; Waisman, H

    1984-01-01

    In male conscious rats provided with a new type of biliary-pancreatic fistula, the effects on basal bile-pancreatic secretion by piprozoline were analyzed when infused intraduodenally superimposed on a "plateau" reached by three previous collection periods of 30 minutes each. Different doses: 25, 50, 100 and 200 mg were evaluated at random during the first 48 hs. of fistula. The secretion evoked by the intraduodenal piprosoline's solvent, propilenglicol, was used as a control reference. The analysis of the percentage secretory changes elicited by piprozoline in respect to the "plateau" put in evidence that this agent exerts a preferential hydrelatic influence namely due to a significant increase in volume. The smallest dose, 25 mg/kg induces a peak volume increase of 30%. The higher dose, 100 and 200 mg/kg give origin to a higher and more sustained response, with peak values of around 70%. Protein and lipase output are also stimulated, but due to a high inter-animal variability the percentage changes are in the borderline of a significant level. It is postulated that piprozoline exerts its influences on basal bile-pancreatic secretion through a stimulation of the hepatic and pancreatic acinar cells and of both hepatic and pancreatic ductal systems. The main mediator of these changes trig by piprozoline would be peptides of the secretin family and duodeno-hepatic and duodeno-pancreatic reflexes. Further clarification through tests in either atropinized or vagotomyzed animals is suggested.

  18. Role of platelet activating factor in pathogenesis of acute pancreatitis in rats.

    PubMed Central

    Konturek, S J; Dembinski, A; Konturek, P J; Warzecha, Z; Jaworek, J; Gustaw, P; Tomaszewska, R; Stachura, J

    1992-01-01

    The importance of platelet activating factor in acute pancreatitis was examined by determining the tissue content of endogenous platelet activating factor and the protective effects of TCV-309, a highly selective platelet activating factor blocker, against caerulein induced pancreatitis in rats. Infusion of caerulein (10 micrograms/kg/h) for five hours resulted in about 70% increase in pancreatic weight, 22% rise in protein content, 50% reduction in tissue blood flow, nine fold increase in tissue level of platelet activating factor and 165% rise in plasma amylase as well as histological evidence of acute pancreatitis. Such infusion of caerulein in chronic pancreatic fistula rats caused a marked increase in protein output from basal secretion of 10 mg/30 minutes to 40 mg/30 minutes in the first hour of infusion followed by a decline in protein output to 15-20 mg/30 minutes in the following hours of the experiment. Exogenous platelet activating factor (50 micrograms/kg) injected ip produced similar alterations in weight, protein content, blood flow, and histology of the pancreas but the increment in serum amylase was significantly smaller and pancreatic secretion was reduced below the basal level. TCV-309 (50 micrograms/kg) given ip before caerulein or platelet activating factor administration significantly reduced the biochemical and morphological alterations caused by caerulein and abolished those induced by exogenous platelet activating factor. These results indicate that platelet activating factor plays an important role in the pathogenesis of acute pancreatitis probably by reducing the blood flow and increasing vascular permeability in the pancreas. PMID:1385272

  19. Role of platelet activating factor in pathogenesis of acute pancreatitis in rats.

    PubMed

    Konturek, S J; Dembinski, A; Konturek, P J; Warzecha, Z; Jaworek, J; Gustaw, P; Tomaszewska, R; Stachura, J

    1992-09-01

    The importance of platelet activating factor in acute pancreatitis was examined by determining the tissue content of endogenous platelet activating factor and the protective effects of TCV-309, a highly selective platelet activating factor blocker, against caerulein induced pancreatitis in rats. Infusion of caerulein (10 micrograms/kg/h) for five hours resulted in about 70% increase in pancreatic weight, 22% rise in protein content, 50% reduction in tissue blood flow, nine fold increase in tissue level of platelet activating factor and 165% rise in plasma amylase as well as histological evidence of acute pancreatitis. Such infusion of caerulein in chronic pancreatic fistula rats caused a marked increase in protein output from basal secretion of 10 mg/30 minutes to 40 mg/30 minutes in the first hour of infusion followed by a decline in protein output to 15-20 mg/30 minutes in the following hours of the experiment. Exogenous platelet activating factor (50 micrograms/kg) injected ip produced similar alterations in weight, protein content, blood flow, and histology of the pancreas but the increment in serum amylase was significantly smaller and pancreatic secretion was reduced below the basal level. TCV-309 (50 micrograms/kg) given ip before caerulein or platelet activating factor administration significantly reduced the biochemical and morphological alterations caused by caerulein and abolished those induced by exogenous platelet activating factor. These results indicate that platelet activating factor plays an important role in the pathogenesis of acute pancreatitis probably by reducing the blood flow and increasing vascular permeability in the pancreas.

  20. The circadian rhythm of melatonin modulates the severity of caerulein-induced pancreatitis in the rat.

    PubMed

    Jaworek, Jolanta; Konturek, Stanisław J; Tomaszewska, Romana; Leja-Szpak, Anna; Bonior, Joanna; Nawrot, Katarzyna; Palonek, Magdalena; Stachura, Jerzy; Pawlik, Wiesław W

    2004-10-01

    Melatonin, an antioxidant, protects the pancreas against acute inflammation but, although this indole is released mainly at night, no study has been undertaken to determine circadian changes of plasma melatonin levels and the severity of acute pancreatitis. The aims of this study were: (a) to compare the severity of caerulein-induced pancreatitis (CIP) produced in the rat during the day and at the night, and (b) to assess the changes of plasma melatonin level and the activity of an antioxidative enzyme; superoxide dismutase (SOD), in the pancreas subjected to CIP during the day time and at night without or with administration of exogenous melatonin or its precursor; l-tryptophan. Rats were kept in 12 hr light/dark cycle. CIP was induced by subcutaneous infusion of caerulein (5 microg/kg/hr for 5 hr). Melatonin (5 or 25 mg/kg) or l-tryptophan (50 or 250 mg/kg) was given intraperitoneally 30 min prior to the start of CIP. CIP induced during the day time was confirmed by histological examination and manifested by pancreatic edema, and rises of amylase and lipase plasma activities (by 400 and 500%, respectively), whereas pancreatic SOD, pancreatic blood flow (PBF) and oxygen consumption by pancreatic tissue (VO(2)) were decreased by 70, 40 and 45%, respectively, as compared with the appropriate controls. All morphological and biochemical parameters of CIP induced at night were significantly less severe, compared with those recorded during the light phase. Plasma melatonin immunoreactivity was significantly higher during the night, than during the day, especially following administration of melatonin or its precursor, which reversed all manifestations of CIP. In conclusion, a circadian rhythm modulates the severity of CIP with a decrease of pancreatitis severity during the night compared with that at the day time and this may be due to the increased plasma level of melatonin and higher activity of SOD in the pancreas.

  1. Role of metabolic programming in the pathogenesis of beta-cell failure in postnatal life.

    PubMed

    Simmons, Rebecca A

    2007-06-01

    Intrauterine growth retardation (IUGR) has been linked to later development of type 2 diabetes in adulthood. Human studies indicate that individuals who were growth retarded at birth have impaired insulin secretion and insulin resistance. Multiple animal models of IUGR demonstrate impaired beta-cell function and development. We have developed a model of IUGR in the rat that leads to diabetes in adulthood with the salient features of most forms of type 2 diabetes in the human: progressive defects in insulin secretion and insulin action prior to the onset of overt hyperglycemia. Decreased beta-cell proliferation leads to a progressive decline in beta-cell mass. Using this model, we have tested the hypothesis that uteroplacental insufficiency disrupts the function of the electron transport chain in the fetal beta-cell and leads to a debilitating cascade of events: increased production of reactive oxygen species, which in turn damage mitochondrial (mt) mtDNA and causes further production of reactive oxygen species (ROS). The net result is progressive loss of beta-cell function and eventual development of type 2 diabetes in the adult. Studies in the IUGR rat also demonstrate that an abnormal intrauterine environment induces epigenetic modifications of key genes regulating beta-cell development; experiments directly link chromatin remodeling with suppression of transcription. Future research will be directed at elucidating the mechanisms underlying epigenetic modifications in offspring.

  2. Anti-monocyte chemoattractant protein 1 gene therapy attenuates experimental chronic pancreatitis induced by dibutyltin dichloride in rats

    PubMed Central

    Zhao, H F; Ito, T; Gibo, J; Kawabe, K; Oono, T; Kaku, T; Arita, Y; Zhao, Q W; Usui, M; Egashira, K; Nawata, H

    2005-01-01

    Background: Monocyte chemoattractant protein 1 (MCP-1) is a member of the C-C chemokine family and exerts strong chemoattractant activity in monocytes, macrophages, and lymphocytes. Rat pancreatic fibrosis induced by dibutyltin dichloride (DBTC) is considered to be an appropriate chronic pancreatitis model histologically and enzymatically, as has demonstrated in a previous study. Aim: We examined the effect of human dominant negative inhibitor of MCP-1 (mutant MCP-1) on progression of chronic pancreatitis induced by DBTC in a rat model. Methods: We used the experimental model of chronic pancreatitis induced by DBTC in rats. Mutant MCP-1 or empty plasmid at a dose of 50 µg/body weight was administrated into rat thigh muscles on days 4, 11, and 18 after administration of DBTC. On days 14 and 28, we evaluated the effect of mutant MCP-1 morphologically and biochemically. Results: The mutant MCP-1 treated group inhibited early pancreatic inflammation and later pancreatic fibrosis histologically, and showed a decrease in serum MCP-1 concentration, intrapancreatic hydroxyproline, α-smooth muscle actin, and an increase in intrapancreatic amylase and protein content compared with the empty plasmid treated group. The mutant MCP-1 group also inhibited intrapancreatic mRNA expression of cytokines and chemokines. Conclusions: : Our findings suggest that monocyte/macrophage recruitment and the systemic MCP-1 signal pathway contribute to progression of chronic pancreatitis, and that blockade of MCP-1 may suppress the development of pancreatic fibrosis. PMID:16284287

  3. [The glutathione system in the blood of rats and morphological changes of the pancreas under experimental acute and chronic pancreatitis].

    PubMed

    Makarchuk, V A; Ushakova, H O; Krylova, O O

    2013-01-01

    In experiment on laboratory rats the models of acute and chronic pancreatitis were developed to study the changes of lipoperoxidation-antioxidant protection system depending on morphological changes of the pancreas. The acute and chronic pancreatitis is accompanied with intensification of lipoperoxidation and gradual inhibition of antioxidant system due to development of subsequent chronization of the pathological process.

  4. Effect of early administration of exogenous basic fibroblast growth factor on acute edematous pancreatitis in rats

    PubMed Central

    Yan, Qiang; Yao, Xing; Dai, Li-Cheng; Zhang, Guo-Lei; Ping, Jin-Liang; He, Jian-Fang; Han, Chun-Fan

    2006-01-01

    AIM: To observe the therapeutic effect of early administration of exogenous Basic fibroblast growth factor (bFGF) on acute edematous pancreatitis (AEP) in rats. METHODS: Thirty male Sprague-Dawley rats were randomly divided into three (n = 10): normal control group (group I), AEP group (group II) and AEP with bFGF treatment group (group III). AEP was induced by subcutaneous injection of cerulein (5.5 μg/kg and 7.5 μg/kg) at 1 h interval into rats of groups II and III. Three hours after induction of AEP, 100 μg/kg bFGF was administrated intraperitoneally for 1h to group III rats. For test of DNA synthesis in acinar cells, 5-bromo-2’-deoxyuridine (BrdU) labeling solution was intraperitoneally injected into the rats of groups II and III 24 h after bFGF treatment. The changes in serum amylase, lipase, pancreatic tissue wet/dry ratio were detected. RESULTS: In bFGF treatment group, there was a significant decrease in the volume of serum amylase, lipase and the pancreatic wet/dry weight ratio(1383.0 ± 94.6 U/L, 194.0 ± 43.6 U/L, 4.32 ± 0.32) compared to AEP group (3464 ± 223.7 U/L, 456 ±68.7 U/L, 6.89 ± 0.47) (P < 0.01), and no significant difference was found between bFGF treatment and control group (1289 ± 94.0 U/L, 171 ± 23.4 U/L, 4.12 ± 0.26, P > 0.05). The inflammatory changes such as interstitial edema, polymorphonuclear neutrophils (PMNs) and vacuolization were significantly ameliorated compared to AEP group (P < 0.01). A small number of BrdU-labeled nuclei were observed in acinar cells of AEP rats (1.8 ± 0.3 nuclei/microscopic field, n = 10) while diffuse BrdU-labeled nuclei were found in bFGF-treated rats (18.9 ± 1.4 nuclei/microscopic field, n = 10) (P < 0.01). Immunohistochemical study showed increased DNA synthesis in pancreatic acinar cells. CONCLUSION: Early administration of exogenous bFGF has significant therapeutic effect on cerulein-induced acute edematous pancreatitis in rats. Its mechanism is related to the amelioration of inflammation

  5. Anti-inflammatory effects of melatonin in a rat model of caerulein-induced acute pancreatitis.

    PubMed

    Carrasco, Cristina; Marchena, Ana M; Holguín-Arévalo, María S; Martín-Partido, Gervasio; Rodríguez, Ana B; Paredes, Sergio D; Pariente, José A

    2013-10-01

    The purpose of our study was to evaluate the protective effect of melatonin in a rat model of caerulein-induced acute pancreatitis. For the induction of experimental acute pancreatitis, four subcutaneous injections of caerulein (20 mgkg–1 body weight) were given to Wistar rats at 2-h intervals. Melatonin was injected intraperitoneally (25 mg kg–1 body weight) 30 min before each caerulein injection. After 12 h, rats were sacrificed by decapitation. Blood and pancreas samples were collected and processed for serological and histopathological studies,respectively. Lipase, a-amylase, corticosterone, total antioxidant power and cytokines interleukin (IL)-1b, IL-4 and tumour necrosis factor(TNF)-a were determined using commercial kits. ANOVA and Tukey tests (P<0.05) were performed for the statistical analysis of the results.Results showed that the administration of melatonin reduced histological damage induced by caerulein treatment as well as the hyperamylasemia and hyperlipidemia. Corticosterone and antioxidant total power were also reverted to basal activities. Furthermore, melatonin pre-treatment reduced pro-inflammatory cytokines IL-1b and TNF-a and increased the serum levels of anti-inflammatory cytokine IL-4. In conclusion,the findings suggest that the protective effect of melatonin in caerulein-induced acute pancreatitis is mediated by the anti-inflammatory ability of this indolamine. Thus, melatonin may have a protective effect against acute pancreatitis.

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

    PubMed

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

    2015-05-01

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

  7. Hypoglycemic and beta cell protective effects of andrographolide analogue for diabetes treatment

    PubMed Central

    2009-01-01

    Background While all anti-diabetic agents can decrease blood glucose level directly or indirectly, few are able to protect and preserve both pancreatic beta cell mass and their insulin-secreting functions. Thus, there is an urgent need to find an agent or combination of agents that can lower blood glucose and preserve pancreatic beta cells at the same time. Herein, we report a dual-functional andrographolide-lipoic acid conjugate (AL-1). The anti-diabetic and beta cell protective activities of this novel andrographolide-lipoic acid conjugate were investigated. Methods In alloxan-treated mice (a model of type 1 diabetes), drugs were administered orally once daily for 6 days post-alloxan treatment. Fasting blood glucose and serum insulin were determined. Pathologic and immunohistochemical analysis of pancreatic islets were performed. Translocation of glucose transporter subtype 4 in soleus muscle was detected by western blot. In RIN-m cells in vitro, the effect of AL-1 on H2O2-induced damage and reactive oxidative species production stimulated by high glucose and glibenclamide were measured. Inhibition of nuclear factor kappa B (NF-κB) activation induced by IL-1β and IFN-γ was investigated. Results In alloxan-induced diabetic mouse model, AL-1 lowered blood glucose, increased insulin and prevented loss of beta cells and their dysfunction, stimulated glucose transport protein subtype 4 (GLUT4) membrane translocation in soleus muscles. Pretreatment of RIN-m cells with AL-1 prevented H2O2-induced cellular damage, quenched glucose and glibenclamide-stimulated reactive oxidative species production, and inhibited cytokine-stimulated NF-κB activation. Conclusion We have demonstrated that AL-1 had both hypoglycemic and beta cell protective effects which translated into antioxidant and NF-κB inhibitory activity. AL-1 is a potential new anti-diabetic agent. PMID:19607676

  8. Effects of phorbol ester on cholecystokinin octapeptide-evoked exocrine pancreatic secretion in the rat.

    PubMed Central

    Francis, L P; Camello, P J; Singh, J; Salido, G M; Madrid, J A

    1990-01-01

    1. A comparative study was made of the effect of the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) on cholecystokinin octapeptide-evoked exocrine pancreatic secretion in the anaesthetized rat and isolated permeabilized pancreatic acinar cells. 2. Cholecystokinin octapeptide (CCK8; 0.10-6.40 nmol (kg body weight)-1) induced dose-dependent increases in pancreatic juice flow, total protein output and amylase release in the anaesthetized rat. 3. Administration of TPA (10(-8) mol (kg body weight)-1) in combination with CCK8 resulted in marked attenuation of the CCK8-evoked secretory response. 4. Simultaneous injection of polymyxin B (10(-8) mol (kg body weight)-1), an inhibitor of protein kinase C, with TPA and CCK8 reversed the inhibitory effect of the phorbol ester on CCK8-induced pancreatic juice flow, total protein output and amylase release. 5. In permeabilized rat pancreatic acini CCK8 (10(-13)-10(-9) M) elicited dose-dependent increases in [3H]leucine-labelled protein secretion (3H-labelled protein release). Combining TPA (10(-8) M) with CCK8 resulted in an inhibition of the CCK8-induced 3H-labelled protein release especially at lower concentrations of CCK8. At higher concentrations of CCK8, TPA was unable to inhibit the CCK8-evoked 3H-labelled protein release. Again, polymyxin B reversed the TPA-induced inhibition of CCK8-evoked 3H-labelled protein output. 6. The results indicate that protein kinase C activation may play an important physiological role in modulating the CCK8-evoked secretory response in rat pancreas in vivo and in vitro. PMID:1712842

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

    PubMed Central

    Granger, Anne; Kushner, Jake A.

    2013-01-01

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

  10. The Importance of REST for Development and Function of Beta Cells

    PubMed Central

    Martin, David; Grapin-Botton, Anne

    2017-01-01

    Beta cells are defined by the genes they express, many of which are specific to this cell type, and ensure a specific set of functions. Beta cells are also defined by a set of genes they should not express (in order to function properly), and these genes have been called forbidden genes. Among these, the transcriptional repressor RE-1 Silencing Transcription factor (REST) is expressed in most cells of the body, excluding most populations of neurons, as well as pancreatic beta and alpha cells. In the cell types where it is expressed, REST represses the expression of hundreds of genes that are crucial for both neuronal and pancreatic endocrine function, through the recruitment of multiple transcriptional and epigenetic co-regulators. REST targets include genes encoding transcription factors, proteins involved in exocytosis, synaptic transmission or ion channeling, and non-coding RNAs. REST is expressed in the progenitors of both neurons and beta cells during development, but it is down-regulated as the cells differentiate. Although REST mutations and deregulation have yet to be connected to diabetes in humans, REST activation during both development and in adult beta cells leads to diabetes in mice. PMID:28286748

  11. Neutrophil elastase inhibitor (ONO-5046) prevents lung hemorrhage induced by lipopolysaccharide in rat model of cerulein pancreatitis.

    PubMed

    Guo, L; Yamaguchi, Y; Ikei, S; Sugita, H; Ogawa, M

    1995-10-01

    The protective effects of a neutrophil elastase inhibitor (ONO-5046) on cerulein-induced pancreatitis followed by a septic challenge with intraperitoneal lipopolysaccharide (LPS) were studied in a rat model. Pancreatitis was induced by four intramuscular injections of cerulein (50 micrograms/kg at 1-hr intervals). ONO-5046 was administered by continuous intravenous infusion via the right jugular vein (50 mg/kg/hr, 30 min prior to the first cerulein injection to 20 hr following the last cerulein injection). Significant differences in serum amylase and pancreatic wet weight ratio were not observed between the animals with pancreatitis treated with or without ONO-5046. There was no significant difference in the in vitro tumor necrosis factor-alpha (TNF-alpha) production by peritoneal macrophages from rats with pancreatitis treated with or without ONO-5046. In a second experiment, LPS (10 mg/kg) was administered intraperitoneally as the septic challenge 6 hr following the first cerulein injection. Lung hemorrhage was seen in the animals with pancreatitis untreated with ONO-5046 24 hr following the first cerulein injection. No significant lung hemorrhage was observed in the animals with pancreatitis treated with ONO-5046 administering 30 min prior to the first cerulein injection. These results suggest that lung hemorrhage in cerulein-induced pancreatitis that follows a septic challenge with LPS can be prevented by the intravenous administration of ONO-5046. Thus there is a significant role for neutrophil elastase in pancreatitis-associated lung injury.

  12. [COMPOSITION OF GASTRIC JUICE AND BILE IN RATS AT THE EXPERIMENTAL CHRONIC PANCREATITIS].

    PubMed

    Gorenko, Z A; Grinchenko, O A; Veselsky, S P; Baban, V M

    2015-01-01

    Chronic pancreatitis is an inflammatory disease of the pancreas, which is characterized by destruction of pancreatic secretory parenchyma and progressing exocrine and endocrine insufficiency. Usually these patients have complications as cardiovascular, renal, respiratory and liver failure, and various gastric dysfunctions. The data of clinical observations do not reveal fully the functional state of the stomach and liver in chronic pancreatitis also remains an open question about the quality of the gastric juices and bile by this pathology. Therefore our aim was to investigate the secretory functions of the stomach and liver features in rats at the experimental chronic pancreatitis. This pathology modeled using L-arginine. Basal gastric secretion was investigated in chronic experiment by aspiration method for 10th and 63rd days, and pancreas and liver--in acute experiments at 13th and 68th days after the last administration of L-arginine. It was established that the character of the secretory response of the digestive tract depends on the duration of the pathology course. On the 10th day the functional state of the gastric secretory glands in rats with chronic pancreatitis characterized by twice increase of gastric acid production but decrease the level of hexosamines on 23.8% (P < 0.001) that indicate a increase of gastric content aggressiveness and mucus producing cells secretory insufficiency. In these animals the rate of total protein decreased on 61.7% (P < 0.05). On the 13th day observed the increase of pancreatic juice on 332% (P < 0.01), hepatic secret volume on 74.9% (P < 0.001) and redistribution in the cholates spectrum: glycocholates level increased but tauro-, free and total dehydroxylated bile acids decreased. These changes suggest deterioration of bile detergent properties, inhibition of acidic pathway of bile acids biosynthesis and conjugation of cholates with taurine. In two months total deficit of amino acids in gastric juice correlated with

  13. Research of Recognition Method of Discrete Wavelet Feature Extraction and PNN Classification of Rats FT-IR Pancreatic Cancer Data

    PubMed Central

    Wan, Chayan; Cao, Wenqing; Cheng, Cungui

    2014-01-01

    Sprague-Dawley (SD) rats' normal and abnormal pancreatic tissues are determined directly by attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy method. In order to diagnose earlier stage of SD rats pancreatic cancer rate with FT-IR, a novel method of extraction of FT-IR feature using discrete wavelet transformation (DWT) analysis and classification with the probability neural network (PNN) was developed. The differences between normal pancreatic and abnormal samples were identified by PNN based on the indices of 4 feature variants. When error goal was 0.01, the total correct rates of pancreatic early carcinoma and advanced carcinoma were 98% and 100%, respectively. It was practical to apply PNN on the basis of ATR-FT-IR to identify abnormal tissues. The research result shows the feasibility of establishing the models with FT-IR-DWT-PNN method to identify normal pancreatic tissues, early carcinoma tissues, and advanced carcinoma tissues. PMID:25548717

  14. Research of Recognition Method of Discrete Wavelet Feature Extraction and PNN Classification of Rats FT-IR Pancreatic Cancer Data.

    PubMed

    Wan, Chayan; Cao, Wenqing; Cheng, Cungui

    2014-01-01

    Sprague-Dawley (SD) rats' normal and abnormal pancreatic tissues are determined directly by attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy method. In order to diagnose earlier stage of SD rats pancreatic cancer rate with FT-IR, a novel method of extraction of FT-IR feature using discrete wavelet transformation (DWT) analysis and classification with the probability neural network (PNN) was developed. The differences between normal pancreatic and abnormal samples were identified by PNN based on the indices of 4 feature variants. When error goal was 0.01, the total correct rates of pancreatic early carcinoma and advanced carcinoma were 98% and 100%, respectively. It was practical to apply PNN on the basis of ATR-FT-IR to identify abnormal tissues. The research result shows the feasibility of establishing the models with FT-IR-DWT-PNN method to identify normal pancreatic tissues, early carcinoma tissues, and advanced carcinoma tissues.

  15. Effects of cerulein and epidermal growth factor on pancreatic growth in the reserpinized rat model.

    PubMed

    Bérubé, F L; Benrezzak, O; Vanier, M; Morisset, J

    1993-07-01

    This study was undertaken to determine the effect of reserpine on rat pancreatic growth, to evaluate if reserpine-caused alterations can be prevented by epidermal growth factor (EGF) and/or cerulein treatment, to evaluate the time course of rat pancreas recovery after reserpine, and to determine if EGF and/or cerulein treatment can accelerate such a recovery. In the first experiment, three groups of male Sprague-Dawley rats (250-265 g) were used. Ad libitum-fed control animals received the reserpine vehicle, and one experimental group received reserpine (1 mg kg-1 day-1 for 7 days) while the other, pair-fed group received the reserpine vehicle with a reduced amount of food to result in malnourishment. Rats from each of these three groups were also assigned to one of four treatments consisting of saline, EGF (10 micrograms kg-1), cerulein (1 microgram kg-1), or a combination (same doses) twice a day for 7 days. In the morning of the 8th day, after an overnight fat, rats were killed. In the second experiment, rats were selected and treated with reserpine or the vehicle as described in experiment 1; after the 7-day treatment, a first cohort of animals was allowed a 30-day recovery period. Three other groups (an ad libitum-fed control, a pair-fed, and a reserpine group) were allowed a 6-day recovery period during which they were treated subcutaneously, twice a day, with either saline, EGF (10 micrograms kg-1), cerulein (1 microgram kg-1), or a combination (same doses). On the morning of the 31st or 7th day, after an overnight fat, rats were killed. After death, all pancreata were examined for weight and protein, amylase, chymotrypsinogen, RNA, and DNA content. In the ad libitum-fed control group, EGF caused pancreatic hypertrophy, whereas cerulein was associated with hypertrophy and hyperplasia. In the pair-fed malnourished group, the EGF effect was limited to slight increases in pancreatic weight and cell mass whereas cerulein caused hypertrophy; EGF plus cerulein

  16. Ascorbic Acid Alleviates Pancreatic Damage Induced by Dibutyltin Dichloride (DBTC) in Rats

    PubMed Central

    Song, Yan-Hua; Fu, Yan-Biao; Qian, Ke-Da

    2007-01-01

    Purpose Because previous studies have reported depleted antioxidant capacity in patients with chronic pancreatitis (CP), prevention of free radical production has gained importance in antifibrotic treatment strategies for CP. The aim of this study was to investigate the effects of ascorbic acid on oxidative capacity and pancreatic damage in experimental CP. Materials and Methods CP was induced in male Sprague-Dawley rats by infusion of dibutyltin dichloride (DBTC) into the tail vein. Ascorbic acid was given intraperitoneally at a daily dose of 10 mg/kg body weight. The treatment groups were as follows: group 1, DBTC plus intraperitoneal physiologic saline; group 2, DBTC plus intraperitoneal ascorbic acid; group 3, solvent plus intraperitoneal physiologic saline; group 4, no operation plus intraperitoneal physiologic saline. Each group contained 15 animals. Treatment was started after CP was established. After 4 weeks of treatment, serum hyaluronic acid and laminin levels were determined by radioimmunoassay, pancreatic tissue oxidative stress was analyzed, and the degree of pancreatic damage was determined. Results Ascorbic acid treatment markedly increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) concentrations in pancreatic tissue (p < 0.01 for both). Significant serum hyaluronic acid and laminin reductions were observed in group 2 as compared with group 1 (p < 0.05). However, the serum hyaluronic acid and laminin levels remained elevated when compared with those of groups 3 and 4 (p < 0.05). Histopathologic scores were also lower in animals with CP that underwent ascorbic acid-treatment (p < 0.05). Conclusion Ascorbic acid treatment alleviated the degree of oxidative stress and pancreatic damage in rat CP. Antioxidant treatment might be considered a potential option to improve the pathologic process in CP. PMID:18159597

  17. Effect of drugs on the pulmonary changes in experimental acute pancreatitis in the rat.

    PubMed Central

    Berry, A R; Taylor, T V

    1982-01-01

    Respiratory complications of acute pancreatitis are well recognised and are closely related to a poor prognosis. Using an experimental model in the rat, a decrease in lung compliance and an increase in lung weight were produced in acute pancreatitis. The effects of dexamethasone, heparin, and aspirin on these changes were studied. The mean specific lung compliance was reduced by 16% in the pancreatitis group compared with the control group (p less than 0.05) and this change was abolished by dexamethasone (p less than 0.02), heparin (p less than 0.01), and aspirin (p less than 0.001). Percentage lung weight (as percentage of total body weight) was raised by 22% in the pancreatitis group compared with the sham operation group (p less than 0.01) and this change was abolished by heparin (p less than 0.01) and aspirin (p less than 0.05), but not affected by dexamethasone (p less than 0.5). The results indicate that 'stiff' and heavy lungs occur in experimental acute pancreatitis. The fact that these changes are abolished by heparin and improved by aspirin suggests that intrapulmonary fibrin deposition is a factor in the pathogenesis of the important respiratory complications of this condition. PMID:7076022

  18. Recombinant interleukin-1 receptor antagonist attenuates the severity of chronic pancreatitis induced by TNBS in rats.

    PubMed

    Xu, Chunfang; Shen, Jiaqing; Zhang, Jing; Jia, Zhenyu; He, Zhilong; Zhuang, Xiaohui; Xu, Ting; Shi, Yuqi; Zhu, Shunying; Wu, Mingyuan; Han, Wei

    2015-02-15

    Chronic pancreatitis (CP) is a common disease in the department of gastroenterology, with the main symptoms of exocrine and/or endocrine insufficiency and abdominal pain. The pathogenic mechanism of CP is still not fully clarified and the aims of treatment now are to relieve symptoms. In this study, we attempted to find a connection between interleukin-1β (IL-1β) and interleukin-1 receptor antagonist (IL-1Ra) in trinitrobenzene sulfonic acid (TNBS)-induced chronic pancreatitis, and then the therapeutic effect of recombinant IL-1Ra was also detected in the CP model. Chronic pancreatitis was induced by intraductal infusion of TNBS in SD rats followed by a consecutive administration of rIL-1Ra, and the histological changes and collagen content in the pancreas were measured, as well as the abdominal hypersensitivity. We found that rhIL-1Ra could attenuate the severity of chronic pancreatic injury, modulate the extracellular matrix secretion, focal proliferation and apoptosis, and cellular immunity in TNBS-induced CP. Interestingly, rIL-1Ra could also block the pancreatitis-induced referred abdominal hypersensitivity. In conclusion, IL-1Ra may play a protective role in CP and rIL-1Ra would be a potential therapeutic target for the treatment of CP, while its possible mechanisms and clinical usage still need further investigation.

  19. Glycyrrhizin Suppresses the Expressions of HMGB1 and Relieves the Severity of Traumatic Pancreatitis in Rats

    PubMed Central

    Luo, Zhulin; Ren, Jiandong; Tian, Fuzhou; Tang, Lijun; Chen, Tao; Dai, Ruiwu

    2014-01-01

    Background High mobility group box 1 (HMGB1) plays important roles in a large variety of diseases; glycyrrhizin (GL) is recognized as an HMGB1 inhibitor. However, few studies have focused on whether glycyrrhizin can potentially improve the outcome of traumatic pancreatitis (TP) by inhibiting HMGB1. Methods A total of 60 male Wistar rats were randomly divided into three groups (n = 20 in each): Control group, TP group and TP-GL group. Pancreatic trauma was established with a custom-made biological impact machine-III, and GL was administered at 15 minutes after the accomplishment of operation. To determine survival rates during the first 7 days after injury, another 60 rats (n = 20 in each) were grouped and treated as mentioned above. At 24 hours of induction of TP, the histopathological changes in pancreas were evaluated and serum amylase levels were tested. Serum tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and HMGB1 were measured using enzyme linked immunosorbent assay. HMGB1 expressions in pancreas were measured using immunohistochemical staining, Western blot and Real-Time PCR analysis. Results Serum levels of HMGB1, TNF-α and IL-6 were increased dramatically in TP group at 24 hours after induction of TP. However, these indicators were reduced significantly by GL administration in TP-GL group comparing with TP group (P<0.05). Meanwhile, survival analysis showed that the seven-day survival rate in TP-GL group was significantly higher than that in TP group (85% versus 65%, P<0.05). GL treatment significantly decreased the pancreatic protein and mRNA expressions of HMGB1 and ameliorated the pancreatic injury in rats with TP. Conclusions Glycyrrhizin might play an important role in improving survival rates and ameliorating pancreatic injury of TP by suppression of the expressions of HMGB1 and other proinflammatory cytokine. PMID:25541713

  20. Functional Improvement in Rats' Pancreatic Islets Using Magnesium Oxide Nanoparticles Through Antiapoptotic and Antioxidant Pathways.

    PubMed

    Moeini-Nodeh, Shermineh; Rahimifard, Mahban; Baeeri, Maryam; Abdollahi, Mohammad

    2017-01-01

    According to undiscovered toxicity and safety of magnesium oxide nanoparticles (MgO NPs) in isolated pancreatic islet cells, this study was designed to examine the effects of its various concentrations on a time-course basis on the oxidative stress, viability, and function of isolated islets of rat's pancreas. Pancreatic islets were isolated and exposed to different MgO NP (<100 nm) concentrations within three different time points. After that, oxidative stress biomarkers were investigated and the best exposure time was selected. Then, safety of MgO NPs was investigated by flow cytometry and fluorescent staining, and levels of insulin secretion and caspase activity were measured. The results illustrated a considerable decrease in oxidative stress markers such as reactive oxygen species (ROS) and lipid peroxidation (LPO) levels of pancreatic islets which were treated by MgO NPs for 24 h. Also, in that time of exposure, cell apoptosis investigation by flow cytometry and insulin test showed that MgO NPs, in a concentration of 100 μg/ml, decreased the rate of apoptotic cells via inhibiting caspase-9 activity and made a significant increase in the level of insulin secretion. Data of function and apoptosis biomarkers correlated with each other. It is concluded that the use of MgO NPs in concentration of as low as 100 μg/ml can induce antiapoptotic, antioxidative, and antidiabetic effects in rat pancreatic islets, which support its possible benefit in islet transplantation procedures.

  1. Oligonucleotide microarray identifies genes differentially expressed during tumorigenesis of DMBA-induced pancreatic cancer in rats.

    PubMed

    Guo, Jun-Chao; Li, Jian; Yang, Ying-Chi; Zhou, Li; Zhang, Tai-Ping; Zhao, Yu-Pei

    2013-01-01

    The extremely dismal prognosis of pancreatic cancer (PC) is attributed, at least in part, to lack of early diagnosis. Therefore, identifying differentially expressed genes in multiple steps of tumorigenesis of PC is of great interest. In the present study, a 7,12-dimethylbenzanthraene (DMBA)-induced PC model was established in male Sprague-Dawley rats. The gene expression profile was screened using an oligonucleotide microarray, followed by real-time quantitative polymerase chain reaction (qRT-PCR) and immunohistochemical staining validation. A total of 661 differentially expressed genes were identified in stages of pancreatic carcinogenesis. According to GO classification, these genes were involved in multiple molecular pathways. Using two-way hierarchical clustering analysis, normal pancreas, acute and chronic pancreatitis, PanIN, early and advanced pancreatic cancer were completely discriminated. Furthermore, 11 upregulated and 142 downregulated genes (probes) were found by Mann-Kendall trend Monotone test, indicating homologous genes of rat and human. The qRT-PCR and immunohistochemistry analysis of CXCR7 and UBe2c, two of the identified genes, confirmed the microarray results. In human PC cell lines, knockdown of CXCR7 resulted in decreased migration and invasion. Collectively, our data identified several promising markers and therapeutic targets of PC based on a comprehensive screening and systemic validation.

  2. Chemopreventive effects of resveratrol in a rat model of cerulein-induced acute pancreatitis.

    PubMed

    Carrasco, Cristina; Holguín-Arévalo, María S; Martín-Partido, Gervasio; Rodríguez, Ana B; Pariente, José A

    2014-02-01

    In the past decades, a greater understanding of acute pancreatitis has led to improvement in mortality rates. Nevertheless, this disease continues to be a health care system problem due to its economical costs. Future strategies such as antioxidant supplementation could be very promising, regarding to beginning and progression of the disease. For this reason, this study was aimed at assessing the effect of exogenous administration of resveratrol during the induction process of acute pancreatitis caused by the cholecystokinin analog cerulein in rats. Resveratrol pretreatment reduced histological damage induced by cerulein treatment, as well as hyperamylasemia and hyperlipidemia. Altered levels of corticosterone, total antioxidant status, and glutathione peroxidase were significantly reverted to control levels by the administration of resveratrol. Lipid peroxidation was also counteracted; nevertheless, superoxide dismutase enzyme was overexpressed due to resveratrol pretreatment. Related to immune response, resveratrol pretreatment reduced pro-inflammatory cytokine IL-1β levels and increased anti-inflammatory cytokine IL-10 levels. In addition, pretreatment with resveratrol in cerulein-induced pancreatitis rats was able to reverse, at least partially, the abnormal calcium signal induced by treatment with cerulein. In conclusion, this study confirms antioxidant and immunomodulatory properties of resveratrol as chemopreventive in cerulein-induced acute pancreatitis.

  3. Pancreatic growth and cell turnover in the rat fed raw soya flour

    SciTech Connect

    Oates, P.S.; Morgan, R.G. )

    1982-08-01

    Growth and differentiation of the pancreatic acinar cell was studied in rats fed raw soya flour (RSF) for up to a year. A second group of rats were fed a control diet. After 1 week of RSF feeding there was a 200% increase in tissue RNA and weight, indicating initial hypertrophy, which was maintained for the 1-year study period. By the second week and over the remainder of the period studied there was also a marked increase in total DNA, suggesting hyperplasia. Cell turnover, as measured by the rate of incorporation of 3H-thymidine into pancreatic DNA, was significantly higher in RSF-fed animals only from the second to fourth weeks; it then returned to control values. Autoradiography showed an 18-fold increase in duct cell labeling at the end of the first week and an 11-fold increase by the end of the second week. Acinar cell labeling doubled from the second to the twelfth week. These studies confirm previous reports that RSF produces pancreatic hypertrophy and hyperplasia. They furthermore show that there is initially marked stimulation of DNA synthesis in the duct cell compartment. The results suggest that cells with the morphologic characteristics of duct cells may be the precursors of acinar cells in hyperplastic pancreatic tissue.

  4. Incretin hormone receptors are required for normal beta cell development and function in female mice.

    PubMed

    Omar, Bilal; Ahlkvist, Linda; Yamada, Yuchiro; Seino, Yutaka; Ahrén, Bo

    2016-05-01

    The incretin hormones, glucose dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1), potentiate insulin secretion and are responsible for the majority of insulin secretion that occurs after a meal. They may also, however, have a fundamental role in pancreatic beta cell development and function, independently of their role in potentiating insulin secretion after a meal. This has led to observations that a loss of GIP or GLP-1 action affects normal beta cell function, however each one of the incretin hormones may compensate when the action of the other is lost and therefore the overall impact of the incretin hormones on beta cell function is not known. We therefore utilized a mouse line deficient in both the GLP-1 and GIP receptor genes, the double incretin receptor knockout (DIRKO), to determine the consequences of a lifelong, complete lack of incretin hormone action on beta cell function, in vivo, in intact animals. We found that DIRKO mice displayed impaired glucose tolerance and insulin secretion in response to both oral glucose and mixed meal tolerance tests compared to wild-type mice. Assessment of beta cell function using the hyperglycemic clamp technique revealed an 80% decrease in first phase insulin response in DIRKO mice, but a normal second phase insulin secretion. A similar decline was seen when wild-type mice were given acute intravenous injection of glucose together with the GLP-1 receptor antagonist Ex9-39. Ex vivo assessments of the pancreas revealed significantly fewer islets in the pancreata of DIRKO mice despite no differences in total pancreatic mass. Insulin secretion from isolated islets of DIRKO mice was impaired to a similar extent to that seen during the hyperglycemic clamp. Insulin secretion in wild-type islets was impaired by acute treatment with Ex9-39 to a similar extent as the in vivo intravenous glucose tolerance tests. In conclusion, a loss of the action of both incretin hormones results in direct impairment

  5. Comparative analysis of pancreatic changes in aged rats fed life long with sunflower, fish, or olive oils.

    PubMed

    Roche, Enrique; Ramírez-Tortosa, César L; Arribas, María I; Ochoa, Julio J; Sirvent-Belando, José E; Battino, Maurizio; Ramírez-Tortosa, M Carmen; González-Alonso, Adrián; Pérez-López, M Patricia; Quiles, José L

    2014-08-01

    An adequate pancreatic structure is necessary for optimal organ function. Structural changes are critical in the development of age-related pancreatic disorders. We aimed to study the effect of oil consumption on pancreas histology in order to find aging-related signs. To this end, three groups of rats were fed an isocaloric diet for 2 years, where virgin olive, sunflower, or fish oil was included. Pancreatic samples for microscopy and blood samples were collected at the moment of sacrifice. As a result, the sunflower oil-fed rats presented higher β-cell numbers and twice the insulin content than virgin olive oil-fed animals. In addition, rats fed with fish oil developed acinar fibrosis and macrophage infiltrates in peri-insular regions, compared with counterparts fed with virgin olive oil. Inflammation signs were less prominent in the sunflower group. The obtained data emphasize the importance of dietary fatty acids in determining pancreatic structure.

  6. Drug CRL 40 028-induced inhibition of pancreatic secretion in rats.

    PubMed

    Rozé, C; Chariot, J; Vaille, C

    1983-09-01

    The drug CRL 40 028 increases spontaneous motility through an action on central adrenergic receptors. The effects of this drug have been tested in rats on the external pancreatic secretion induced by secretin, CCK, acetylcholine, vagal electrical stimulation or 2 deoxy-D-glucose. CRL 40 028 had no effect on basal secretion nor on secretion stimulated by agents acting directly on pancreatic secretory cells (secretin, CCK, acetylcholine), but decreased significantly secretion induced by central or peripheral stimulation of the vagus nerves. CRL 40 028-induced inhibition of 2 DG effect was reduced by yohimbine, suggesting a participation of alpha 2-adrenergic receptors in the action of CRL 40 028 on the exocrine pancreas secretion of rats.

  7. Large molecule protein feeding during the suckling period is required for the development of pancreatic digestive functions in rats.

    PubMed

    Kinouchi, Toshi; Koyama, Satomi; Harada, Etsumori; Yajima, Takaji

    2012-12-15

    We examined if large molecule protein feeding during the suckling period is prerequisite for the proper development of pancreatic digestive functions. Most amino acids in breast milk exist as the constituent of large proteins and not as oligopeptides or free amino acids. Accumulating evidence indicates the nutritional importance of large protein feeding for suckling infants; however, evidence on the physiological significance remains small. We thus artificially reared rat pups on a standard rat formula with milk protein or a formula with milk protein hydrolysate from 7 to 21 days of age, and thereafter, fed a standard solid diet until 42 days of age. Pancreas weight and the stock of pancreatic digestive enzymes in the hydrolysate-fed rats were significantly lower than those in the protein-fed rats during and also after the suckling period. Plasma insulin, a stimulator of amylase synthesis, was also significantly low in the hydrolysate-fed rats compared with the protein-fed rats. At 28 days of age, we evaluated the pancreatic secretory ability in response to dietary protein and cholecystokinin (CCK) by means of pancreatic duct cannulation. Pancreatic secretion stimulated by dietary protein in the hydrolysate-fed rats was significantly weaker than that in the protein-fed rats. No significant difference was observed in the increasing rate of pancreatic enzyme secretion in response to CCK between the two groups. These results suggest that the presence of large proteins in breast milk is significant for the development of pancreatic digestive functions and the outcomes could remain even later on in life.

  8. Lithospermic acid B protects beta-cells from cytokine-induced apoptosis by alleviating apoptotic pathways and activating anti-apoptotic pathways of Nrf2-HO-1 and Sirt1

    SciTech Connect

    Lee, Byung-Wan; Chun, Sung Wan; Kim, Soo Hyun; Lee, Yongho; Kang, Eun Seok; Cha, Bong-Soo; Lee, Hyun Chul

    2011-04-01

    Lithospermic acid B (LAB) has been reported to protect OLETF rats, an established type 2 diabetic animal model, from the development of diabetes-related vascular complications. We investigated whether magnesium lithospermate B (LAB) has a protective role under cytokine-induced apoptosis in INS-1 cells in vitro and whether it slows the development of diabetes in OLETF rats in vivo. Pretreatment with 50 {mu}M LAB significantly reduced the 1000 U/mL INF-{gamma} and 100 U/mL IL-1{beta}-induced INS-1 cell death. LAB significantly alleviated cytokine-induced phosphorylations of p38 and JNK in accordance with a decrease in cleaved caspase-3 activity in beta-cells. LAB also protected against the cytokine-induced caspase-3 apoptotic pathway via significant activation of Nrf2-HO (heme-oxigenase)-1 and Sirt1 expression. OLETF rats treated with 40 mg/kg/day LAB showed a significant improvement in glucose tolerance compared to untreated OLETF control rats in vivo. Our results suggest that the cytoprotective effects of LAB on pancreatic {beta}-cells are related with both alleviating apoptotic pathways and activating anti-apoptotic pathways of Nrf2-HO-1 and Sirt1.

  9. Increased activity of group II phospholipase A2 in plasma in rat sodium deoxycholate induced acute pancreatitis

    PubMed Central

    Furue, S; Hori, Y; Kuwabara, K; Ikeuchi, J; Onoyama, H; Yamamoto, M; Tanaka, K

    1997-01-01

    Background—Two different types of secretory phospholipase A2 (PLA2), pancreatic group I (PLA2-I) and non-pancreatic group II (PLA2-II), have been identified and postulated to be associated with the pathogenesis of various diseases, such as acute pancreatitis, septic shock, and multiple organ failure. 
Aims—To investigate the type of secretory PLA2 responsible for its catalytic activity found in plasma and ascites of experimental acute pancreatitis. 
Methods—Acute pancreatitis of differing severity was induced by the injection of different concentrations (1% or 10%) of sodium deoxycholate (DCA) into the common biliopancreatic duct in rats, and catalytic PLA2 activity in plasma and ascites were differentiated by anti-PLA2-I antibody and specific inhibitor of PLA2-II. Survival rate and plasma amylase, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were also measured.
Results—In 1% and 10% DCA induced acute pancreatitis, plasma amylase values as well as PLA2 activity in ascites were greatly increased. PLA2 activity in plasma was also notably increased in 10% DCA induced acute pancreatitis, but not in 1% DCA induced acute pancreatitis. PLA2-I specific polyclonal antibody significantly inhibited PLA2 activity in ascites but not that in plasma. In contrast, plasma PLA2 activity was completely suppressed by PLA2-II specific inhibitor. In addition, a high mortality (93% at five hours) and a significant increase in plasma AST and ALT were noted in 10% DCA induced pancreatitis. 
Conclusion—Ascites PLA2 activity is mainly derived from PLA2-I, whereas plasma PLA2 activity is mostly derived from PLA2-II in severe acute pancreatitis, suggesting that increased plasma PLA2-II activity might be implicated in hepatic failure arising after severe acute pancreatitis. 

 Keywords: acute pancreatitis; phospholipase A2; sodium deoxycholate pancreatitis; hepatic failure PMID:9462218

  10. Influence of acute pancreatitis on the in vitro responsiveness of rat mesenteric and pulmonary arteries

    PubMed Central

    Camargo, Enilton A; Delbin, Maria Andréia; Ferreira, Tatiane; Landucci, Elen CT; Antunes, Edson; Zanesco, Angelina

    2008-01-01

    Background Acute pancreatitis is an inflammatory disease characterized by local tissue injury and systemic inflammatory response leading to massive nitric oxide (NO) production and haemodynamic disturbances. Therefore, the aim of this work was to evaluate the vascular reactivity of pulmonary and mesenteric artery rings from rats submitted to experimental pancreatitis. Male Wistar rats were divided into three groups: saline (SAL); tauracholate (TAU) and phospholipase A2 (PLA2). Pancreatitis was induced by administration of TAU or PLA2 from Naja mocambique mocambique into the common bile duct of rats, and after 4 h of duct injection the animals were sacrificed. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP) and phenylephrine (PHE) in isolated mesenteric and pulmonary arteries were obtained. Potency (pEC50) and maximal responses (EMAX) were determined. Blood samples were collected for biochemical analysis. Results In mesenteric rings, the potency for ACh was significantly decreased from animals treated with TAU (about 4.2-fold) or PLA2 (about 6.9-fold) compared to saline group without changes in the maximal responses. Neither pEC50 nor EMAX values for Ach were altered in pulmonary rings in any group. Similarly, the pEC50 and the EMAX values for SNP were not changed in both preparations in any group. The potency for PHE was significantly decreased in rat mesenteric and pulmonary rings from TAU group compared to SAL group (about 2.2- and 2.69-fold, for mesenteric and pulmonary rings, respectively). No changes were seen in the EMAX for PHE. The nitrite/nitrate (NOx-) levels were markedly increased in animals submitted to acute pancreatitis as compared to SAL group, approximately 76 and 68% in TAU and PLA2 protocol, respectively. Conclusion Acute pancreatitis provoked deleterious effects in endothelium-dependent relaxing response for ACh in mesenteric rings that were strongly associated with high plasma NOx- levels as consequence of

  11. Leptin treatment ameliorates acute lung injury in rats with cerulein-induced acute pancreatitis

    PubMed Central

    Gultekin, Fatma Ayca; Kerem, Mustafa; Tatlicioglu, Ertan; Aricioglu, Aysel; Unsal, Cigdem; Bukan, Neslihan

    2007-01-01

    AIM: To determine the effect of exogenous leptin on acute lung injury (ALI) in cerulein-induced acute pancreatitis (AP). METHODS: Forty-eight rats were randomly divided into 3 groups. AP was induced by intraperitoneal (i.p.) injection of cerulein (50 μg/kg) four times, at 1 h intervals. The rats received a single i.p. injection of 10 μg/kg leptin (leptin group) or 2 mL saline (AP group) after cerulein injections. In the sham group, animals were given a single i.p. injection of 2 mL saline. Experimental samples were collected for biochemical and histological evaluations at 24 h and 48 h after the induction of AP or saline administration. Blood samples were obtained for the determination of amylase, lipase, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, macrophage inflammatory peptide (MIP)-2 and soluble intercellular adhesion molecule (sICAM)-1 levels, while pancreatic and lung tissues were removed for myeloperoxidase (MPO) activity, nitric oxide (NOx) level, CD40 expression and histological evaluation. RESULTS: Cerulein injection caused severe AP, confirmed by an increase in serum amylase and lipase levels, histopathological findings of severe AP, and pancreatic MPO activity, compared to the values obtained in the sham group. In the leptin group, serum levels of MIP-2, sICMA-1, TNF-α, and IL-1β, pancreatic MPO activity, CD40 expression in pancreas and lung tissues, and NOx level in the lung tissue were lower compared to those in the AP group. Histologically, pancreatic and lung damage was less severe following leptin administration. CONCLUSION: Exogenous leptin attenuates inflamma-tory changes, and reduces pro-inflammatory cytokines, nitric oxide levels, and CD40 expression in cerulein-induced AP and may be protective in AP associated ALI. PMID:17589942

  12. Amazing pancreas: specific regulation of pancreatic secretion of individual digestive enzymes in rats.

    PubMed

    Maouyo, D; Morisset, J

    1995-02-01

    We investigated the effects of somatostatin (SMS)-201-995, atropine, and MK-329 on the role of cholinergic- and cholecystokinin-related systems and on the secretory relationship between five pancreatic digestive enzymes in rats. Animals kept in restraint cages and provided with pancreatic, biliary, duodenal, and jugular vein cannulas were treated as follows: 1) 0.25 micrograms.kg-1.h-1 caerulein alone, 2) both 0.25 micrograms.kg-1.h-1 caerulein and 100 micrograms.kg-1.h-1 atropine, 3) both caerulein and 5 micrograms.kg-1.h-1 SMS, 4) 91.3 micrograms.kg-1.h-1 carbachol alone, 5) both carbachol and 0.5 mg.kg-1.h-1 MK-329, and 6) both carbachol and 5 micrograms.kg-1.h-1 SMS, respectively. Food, but not water, was denied rats starting 10 h before the experiment and throughout the 6-h experimental period. The secretory patterns over the 6-h experimental period showed noticeably independent regulation of pancreatic secretion of individual digestive enzymes. The relationship between paired enzymes significantly varied according to the treatment. The correlation between chymotrypsinogen and the other enzymes was markedly modulated by MK-329. Our results suggest that SMS is a major "gate-keeper" in the regulation of exocrine pancreatic secretion and that the secretion of each digestive enzyme is individually regulated. Furthermore, they suggest that cholecystokinin and acetylcholine and their respective agonists are essentially initiators of secretory processes of the pancreas. Therefore, the paradigms of the regulation of pancreatic secretion heretofore accepted should be reexamined.

  13. Damage to pancreatic acinar cells and preservation of islets of Langerhans in a rat model of acute pancreatitis induced by Karwinskia humboldtiana (buckthorn).

    PubMed

    Carcano-Diaz, Katya; Garcia-Garcia, Aracely; Segoviano-Ramirez, Juan Carlos; Rodriguez-Rocha, Humberto; Loera-Arias, Maria de Jesus; Garcia-Juarez, Jaime

    2016-09-01

    Karwinskia humboldtiana (Kh) is a poisonous plant that grows in some regions of the American continent. Consuming large amounts of Kh fruit results in acute intoxication leading to respiratory failure, culminating in death within days. There is evidence of histological damage to the lungs, liver, and kidneys following accidental and experimental Kh intoxication. To date, the microscopic effect of Kh consumption on the pancreas has not been described. We examined the early effects of Kh fruit on pancreatic tissue at different stages of acute intoxication in the Wistar rat. We found progressive damage confined to the exocrine pancreas, starting with a reduction in the number of zymogen granules, loss of acinar architecture, the presence of autophagy-like vesicles, apoptosis and inflammatory infiltrate. The pancreatic pathology culminated in damaged acini characterized by necrosis and edema, with a complete loss of lobular architecture. Interestingly, the morphology of the islets of Langerhans was conserved throughout our evaluations. Taken together, our results indicate the damage induced by a high dose of Kh fruit in the Wistar rat is consistent with an early acute necrotizing pancreatitis that exclusively affects the exocrine pancreas. Therefore, this system might be useful as an animal model to study the treatment of pancreatic diseases. More importantly, as the islets of Langerhans were preserved, the active compounds of Kh fruit could be utilized for the treatment of acinar pancreatic cancer. Further studies might provide insight into the severity of acute Kh intoxication in humans and influence the design of treatments for pancreatic diseases and acinar pancreatic cancer.

  14. Protective effect of central thyrotropin-releasing hormone analog on cerulein-induced acute pancreatitis in rats.

    PubMed

    Yoneda, Masashi; Goto, Manabu; Nakamura, Kimihide; Shimada, Tadahito; Hiraishi, Hideyuki; Terano, Akira; Haneda, Masakazu

    2005-02-15

    Central neuropeptides play a role in many physiological functions through the autonomic nervous system. We have recently demonstrated that central injection of a thyrotropin-releasing hormone (TRH) analog increases pancreatic blood flow through vagal and nitric oxide-dependent pathways. In this study, the central effect of a TRH analog on experimental acute pancreatitis was investigated in rats. Acute pancreatitis was induced by two intraperitoneal injections of cerulein (40 microg/kg) at 1-h interval. Either stable TRH analog, RX 77368 (5-100 ng), or saline was injected intracisternally 15 min before the first cerulein injection under ether anesthesia. Serum amylase level was measured before and 5 h after the first cerulein injection. Pancreatic wet/dry weight ratio and histological changes were also evaluated. Intracisternal TRH analog inhibited cerulean-induced elevation of serum amylase level, increase in pancreatic wet/dry weight ratio and pancreatic histological changes, such as interstitial edema, inflammation and vacuolization. The pancreatic cytoprotection induced by central TRH analog was abolished by subdiaphragmatic vagotomy and N(G)-nitro-L-arginine-methyl ester (L-NAME), but not by 6-hydroxydopamine (6-OHDA). Intravenous administration of the TRH analog did not influence cerulein-induced acute pancreatitis. These results indicate that the TRH analog acts in the central nervous system to protect against acute pancreatitis through vagal and nitric oxide-dependent pathways.

  15. A human beta cell line with drug inducible excision of immortalizing transgenes

    PubMed Central

    Benazra, Marion; Lecomte, Marie-José; Colace, Claire; Müller, Andreas; Machado, Cécile; Pechberty, Severine; Bricout-Neveu, Emilie; Grenier-Godard, Maud; Solimena, Michele; Scharfmann, Raphaël; Czernichow, Paul; Ravassard, Philippe

    2015-01-01

    Objectives Access to immortalized human pancreatic beta cell lines that are phenotypically close to genuine adult beta cells, represent a major tool to better understand human beta cell physiology and develop new therapeutics for Diabetes. Here we derived a new conditionally immortalized human beta cell line, EndoC-βH3 in which immortalizing transgene can be efficiently removed by simple addition of tamoxifen. Methods We used lentiviral mediated gene transfer to stably integrate a tamoxifen inducible form of CRE (CRE-ERT2) into the recently developed conditionally immortalized EndoC βH2 line. The resulting EndoC-βH3 line was characterized before and after tamoxifen treatment for cell proliferation, insulin content and insulin secretion. Results We showed that EndoC-βH3 expressing CRE-ERT2 can be massively amplified in culture. We established an optimized tamoxifen treatment to efficiently excise the immortalizing transgenes resulting in proliferation arrest. In addition, insulin expression raised by 12 fold and insulin content increased by 23 fold reaching 2 μg of insulin per million cells. Such massive increase was accompanied by enhanced insulin secretion upon glucose stimulation. We further observed that tamoxifen treated cells maintained a stable function for 5 weeks in culture. Conclusions EndoC βH3 cell line represents a powerful tool that allows, using a simple and efficient procedure, the massive production of functional non-proliferative human beta cells. Such cells are close to genuine human beta cells and maintain a stable phenotype for 5 weeks in culture. PMID:26909308

  16. Local disruption of the celiac ganglion inhibits substance P release and ameliorates caerulein-induced pancreatitis in rats.

    PubMed

    Noble, Marc D; Romac, Joelle; Wang, Yu; Hsu, Jay; Humphrey, John E; Liddle, Rodger A

    2006-07-01

    Primary sensory neurons of the C and Adelta subtypes express the vanilloid capsaicin receptor TRPV1 and contain proinflammatory peptides such as substance P (SP) that mediate neurogenic inflammation. Pancreatic injury stimulates these neurons causing the release of SP in the pancreas resulting in pancreatic edema and neutrophil infiltration that contributes to pancreatitis. Axons of primary sensory neurons innervating the pancreas course through the celiac ganglion. We hypothesized that disruption of the celiac ganglion by surgical excision or inhibition of C and Adelta fibers through blockade of TRPV1 would reduce the severity of experimental pancreatitis by inhibiting neurogenic inflammation. Resiniferatoxin (RTX) is a specific TRPV1 agonist that, in high doses, selectively destroys C and Adelta fibers. Sprague-Dawley rats underwent surgical ganglionectomy or application of 10 microg RTX (vs. vehicle alone) to the celiac ganglion. One week later, pancreatitis was induced by six hourly intraperitoneal injections of caerulein (50 microg/kg). The severity of pancreatitis was assessed by serum amylase, pancreatic edema, and pancreatic myeloperoxidase (MPO) activity. SP receptor (neurokinin-1 receptor, NK-1R) internalization in acinar cells, used as an index of endogenous SP release, was assessed by immunocytochemical quantification of NK-1R endocytosis. Caerulein administration caused significant increases in pancreatic edema, serum amylase, MPO activity, and NK-1R internalization. RTX treatment and ganglionectomy significantly reduced pancreatic edema by 46% (P < 0.001) and NK-1R internalization by 80% and 51% (P < 0.001 and P < 0.05, respectively). RTX administration also significantly reduced MPO activity by 47% (P < 0.05). Neither treatment affected serum amylase, consistent with a direct effect of caerulein. These results demonstrate that disruption of or local application of RTX to the celiac ganglion inhibits SP release in the pancreas and reduces the severity

  17. Exercise at anaerobic threshold intensity and insulin secretion by isolated pancreatic islets of rats

    PubMed Central

    de Oliveira, Camila Aparecida Machado; Paiva, Mauricio Ferreira; Mota, Clécia Alencar Soares; Ribeiro, Carla; de Almeida Leme, José Alexandre Curiacos; Luciano, Eliete

    2010-01-01

    To evaluate the effect of acute exercise and exercise training at the anaerobic threshold (AT) intensity on aerobic conditioning and insulin secretion by pancreatic islets, adult male Wistar rats were submitted to the lactate minimum test (LMT) for AT determination. Half of the animals were submitted to swimming exercise training (trained), 1 h/day, 5 days/week during 8 weeks, with an overload equivalent to the AT. The other half was kept sedentary. At the end of the experimental period, the rats were submitted to an oral glucose tolerance test and to another LMT. Then, the animals were sacrificed at rest or immediately after 20 minutes of swimming exercise at the AT intensity for pancreatic islets isolation. At the end of the experiment mean workload (% bw) at AT was higher and blood lactate concentration (mmol/L) was lower in the trained than in the control group. Rats trained at the AT intensity showed no alteration in the areas under blood glucose and insulin during OGTT test. Islet insulin content of trained rats was higher than in the sedentary rats while islet glucose uptake did not differ among the groups. The static insulin secretion in response to the high glucose concentration (16.7 mM) of the sedentary group at rest was lower than the sedentary group submitted to the acute exercise and the inverse was observed in relation to the trained groups. Physical training at the AT intensity improved the aerobic condition and altered insulin secretory pattern by pancreatic islets. PMID:21099318

  18. Molecular mechanisms of tungstate-induced pancreatic plasticity: a transcriptomics approach

    PubMed Central

    Altirriba, Jordi; Barbera, Albert; Del Zotto, Héctor; Nadal, Belen; Piquer, Sandra; Sánchez-Pla, Alex; Gagliardino, Juan J; Gomis, Ramon

    2009-01-01

    Background Sodium tungstate is known to be an effective anti-diabetic agent, able to increase beta cell mass in animal models of diabetes, although the molecular mechanisms of this treatment and the genes that control pancreas plasticity are yet to be identified. Using a transcriptomics approach, the aim of the study is to unravel the molecular mechanisms which participate in the recovery of exocrine and endocrine function of streptozotocin (STZ) diabetic rats treated with tungstate, determining the hyperglycemia contribution and the direct effect of tungstate. Results Streptozotocin (STZ)-diabetic rats were treated orally with tungstate for five weeks. Treated (STZ)-diabetic rats showed a partial recovery of exocrine and endocrine function, with lower glycemia, increased insulinemia and amylasemia, and increased beta cell mass achieved by reducing beta cell apoptosis and raising beta cell proliferation. The microarray analysis of the pancreases led to the identification of three groups of differentially expressed genes: genes altered due to diabetes, genes restored by the treatment, and genes specifically induced by tungstate in the diabetic animals. The results were corroborated by quantitative PCR. A detailed description of the pathways involved in the pancreatic effects of tungstate is provided in this paper. Hyperglycemia contribution was studied in STZ-diabetic rats treated with phloridzin, and the direct effect of tungstate was determined in INS-1E cells treated with tungstate or serum from untreated or treated STZ-rats, observing that tungstate action in the pancreas takes places via hyperglycemia-independent pathways and via a combination of tungstate direct and indirect (through the serum profile modification) effects. Finally, the MAPK pathway was evaluated, observing that it has a key role in the tungstate-induced increase of beta cell proliferation as tungstate activates the mitogen-activated protein kinase (MAPK) pathway directly by increasing p42/p44

  19. Efficient gene delivery to pancreatic islets with ultrasonic microbubble destruction technology

    NASA Astrophysics Data System (ADS)

    Chen, Shuyuan; Ding, Jia-Huan; Bekeredjian, Raffi; Yang, Bing-Zhi; Shohet, Ralph V.; Johnston, Stephen A.; Hohmeier, Hans E.; Newgard, Christopher B.; Grayburn, Paul A.

    2006-05-01

    This study describes a method of gene delivery to pancreatic islets of adult, living animals by ultrasound targeted microbubble destruction (UTMD). The technique involves incorporation of plasmids into the phospholipid shell of gas-filled microbubbles, which are then infused into rats and destroyed within the pancreatic microcirculation with ultrasound. Specific delivery of genes to islet beta cells by UTMD was achieved by using a plasmid containing a rat insulin 1 promoter (RIP), and reporter gene expression was regulated appropriately by glucose in animals that received a RIP-luciferase plasmid. To demonstrate biological efficacy, we used UTMD to deliver RIP-human insulin and RIP-hexokinase I plasmids to islets of adult rats. Delivery of the former plasmid resulted in clear increases in circulating human C-peptide and decreased blood glucose levels, whereas delivery of the latter plasmid resulted in a clear increase in hexokinase I protein expression in islets, increased insulin levels in blood, and decreased circulating glucose levels. We conclude that UTMD allows relatively noninvasive delivery of genes to pancreatic islets with an efficiency sufficient to modulate beta cell function in adult animals. diabetes | gene therapy | ultrasound

  20. Hepatic steatosis depresses alpha-1-antitrypsin levels in human and rat acute pancreatitis

    PubMed Central

    Wang, Qian; Du, Jianjun; Yu, Pengfei; Bai, Bin; Zhao, Zhanwei; Wang, Shiqi; Zhu, Junjie; Feng, Quanxin; Gao, Yun; Zhao, Qingchuan; Liu, Chaoxu

    2015-01-01

    Hepatic steatosis (HS) can exacerbate acute pancreatitis (AP). This study aimed to investigate the relation between α1-antitrypsin (AAT) and acute pancreatitis when patients have HS. Using proteomic profiling, we identified 18 differently expressed proteins pots in the serum of rats with or without HS after surgical establishment of AP. AAT was found to be one of the significantly down-regulated proteins. AAT levels were significantly lower in hepatic steatosis acute pancreatitis (HSAP) than in non-HSAP (NHSAP) (P < 0.001). To explore the clinical significance of these observations, we measured the levels of AAT in the serum of 240 patients with HSAP, NHSAP, fatty liver disease (FLD), or no disease. Compared with healthy controls, serum AAT levels in patients with NHSAP were significantly higher (P < 0.01), while in patients with HSAP serum AAT levels were significantly lower (P < 0.01). Further studies showed that acute physiology and chronic health evaluation (APACHE-II) scores were negatively correlated with serum AAT levels (r = −0.85, P < 0.01). In conclusion, low serum levels of AAT in patients with HSAP are correlated with disease severity and AAT may represent a potential target for therapies aiming to improve pancreatitis. PMID:26634430

  1. Hepatic steatosis depresses alpha-1-antitrypsin levels in human and rat acute pancreatitis.

    PubMed

    Wang, Qian; Du, Jianjun; Yu, Pengfei; Bai, Bin; Zhao, Zhanwei; Wang, Shiqi; Zhu, Junjie; Feng, Quanxin; Gao, Yun; Zhao, Qingchuan; Liu, Chaoxu

    2015-12-04

    Hepatic steatosis (HS) can exacerbate acute pancreatitis (AP). This study aimed to investigate the relation between α1-antitrypsin (AAT) and acute pancreatitis when patients have HS. Using proteomic profiling, we identified 18 differently expressed proteins pots in the serum of rats with or without HS after surgical establishment of AP. AAT was found to be one of the significantly down-regulated proteins. AAT levels were significantly lower in hepatic steatosis acute pancreatitis (HSAP) than in non-HSAP (NHSAP) (P < 0.001). To explore the clinical significance of these observations, we measured the levels of AAT in the serum of 240 patients with HSAP, NHSAP, fatty liver disease (FLD), or no disease. Compared with healthy controls, serum AAT levels in patients with NHSAP were significantly higher (P < 0.01), while in patients with HSAP serum AAT levels were significantly lower (P < 0.01). Further studies showed that acute physiology and chronic health evaluation (APACHE-II) scores were negatively correlated with serum AAT levels (r = -0.85, P < 0.01). In conclusion, low serum levels of AAT in patients with HSAP are correlated with disease severity and AAT may represent a potential target for therapies aiming to improve pancreatitis.

  2. Microarray analysis of pancreatic gene expression during biotin repletion in biotin-deficient rats.

    PubMed

    Dakshinamurti, Krishnamurti; Bagchi, Rushita A; Abrenica, Bernard; Czubryt, Michael P

    2015-12-01

    Biotin is a B vitamin involved in multiple metabolic pathways. In humans, biotin deficiency is relatively rare but can cause dermatitis, alopecia, and perosis. Low biotin levels occur in individuals with type-2 diabetes, and supplementation with biotin plus chromium may improve blood sugar control. The acute effect on pancreatic gene expression of biotin repletion following chronic deficiency is unclear, therefore we induced biotin deficiency in adult male rats by feeding them a 20% raw egg white diet for 6 weeks. Animals were then randomized into 2 groups: one group received a single biotin supplement and returned to normal chow lacking egg white, while the second group remained on the depletion diet. After 1 week, pancreata were removed from biotin-deficient (BD) and biotin-repleted (BR) animals and RNA was isolated for microarray analysis. Biotin depletion altered gene expression in a manner indicative of inflammation, fibrosis, and defective pancreatic function. Conversely, biotin repletion activated numerous repair and anti-inflammatory pathways, reduced fibrotic gene expression, and induced multiple genes involved in pancreatic endocrine and exocrine function. A subset of the results was confirmed by quantitative real-time PCR analysis, as well as by treatment of pancreatic AR42J cells with biotin. The results indicate that biotin repletion, even after lengthy deficiency, results in the rapid induction of repair processes in the pancreas.

  3. Infusion of Bone Marrow Mesenchymal Stem Cells Attenuates Experimental Severe Acute Pancreatitis in Rats

    PubMed Central

    Huang, Dandan; Gao, Jun; Gong, Yanfang; Wu, Hongyu; Xu, Aifang

    2016-01-01

    Background & Aims. Severe acute pancreatitis (SAP) remains a high-mortality disease. Bone marrow (BM) mesenchymal stem cells (MSCs) have been demonstrated to have plasticity of transdifferentiation and to have immunomodulatory functions. In the present study, we assessed the roles of MSCs in SAP and the therapeutic effects of MSC on SAP after transplantation. Methods. A pancreatitis rat model was induced by the injection of taurocholic acid (TCA) into the pancreatic duct. After isolation and characterization of MSC from BM, MSC transplantation was conducted 24 hrs after SAP induction by tail vein injection. The survival rate was observed and MSCs were traced after transplantation. The expression of TNF-α and IL-1β mRNA in the transplantation group was also analyzed. Results. The survival rate of the transplantation group was significantly higher compared to the control group (p < 0.05). Infused MSCs were detected in the pancreas and BM 3 days after transplantation. The expression of TNF-α and IL-1β mRNA in the transplantation group was significantly lower than in the control group in both the pancreas and the lungs (p < 0.05). Conclusions. MSC transplantation could improve the prognosis of SAP rats. Engrafted MSCs have the capacity of homing, migration, and planting during the treatment of SAP. PMID:27721836

  4. Ultrastructural aspects of acute pancreatitis induced by 2, 2'-azobis (2-amidinopropane) dihydrochloride (AAPH) in rats.

    PubMed

    Tukaj, C; Olewniak-Adamowska, A; Pirski, M I; Woźniak, M

    2012-08-01

    Pathophysiology of acute pancreatitis (AP) has not been clearly established; nevertheless, accumulating evidence implicates highly reactive oxygen species (ROS) as important mediators of exocrine tissue damage. In this study, we used a water-soluble radical initiator, 2,2 -azobis-(2-amidinopropane) dihydrochloride (AAPH), to investigate the consequences of oxidative stress insult to the rat pancreas. The detailed characterisation of acini ultrastructural changes in the early course (3, 6, 12, 24 h) of AAPH-induced pancreatitis (40 mg/1 kg body weight) was performed. Considerable damage to the mitochondria in acinar cells manifested by increased translucence of the matrix, partial destruction of cristae, and formation of myelin figures were noted. At the same time, focal dilation, degranulation of rough endoplasmic reticulum, and reduced number of zymogen granules was observed. The most prominent ultrastructural feature was accumulation of highly polymorphic cytoplasmic vacuoles in acinar cells. Double membrane-bound autophagosomes, different in size and shape, with sequestered organelles, autophagolysosomes, and large, empty, single-membrane-bound vacuoles were observed within the cytoplasm. The results indicate that intensive and impaired autophagy mediates pathological accumulation of vacuoles in acinar cells. The rat model of acute pancreatitis induced by AAPH is useful to investigate the early events of oxidative stress insult to the pancreas.

  5. Differentiation of pancreatic acinar carcinoma cells cultured on rat testicular seminiferous tubular basement membranes

    SciTech Connect

    Watanabe, T.K.; Hansen, L.J.; Reddy, N.K.; Kanwar, Y.S.; Reddy, J.K.

    1984-11-01

    The use of rat testicular seminiferous tubular basement membrane (STBM) segments as a model substratum for the in vitro maintenance of tumor cells dissociated from a transplantable pancreatic acinar rat carcinoma is described. Ultrastructurally pure, hollow tubular segments of STBM were prepared by mechanical disaggregation, DNase digestion, and deoxycholate treatment. Dissociated pancreatic acinar carcinoma cells adhered readily to STBM segments within 1 to 6 hr, and these STBM-tumor cell aggregates were maintained for up to 7 days in serum-free chemically defined medium supplemented with hydrocortisone, insulin, vitamin C, and soybean trypsin inhibitor. The tumor cells formed acinar-like clusters and displayed intercellular junctions and polarization of secretory granules toward the center of these clusters. By 4 days, virtually all cells of this acinar carcinoma maintained on STBM in supplemented chemically defined medium contained numerous secretory granules. Cell replication, as determined by (/sup 3/H)thymidine autoradiography, ceased within 18 hr of attachment of neoplastic cells to STBM; however, all cells incorporated (/sup 3/H)leucine as evidenced by light and electron microscopic autoradiography. In addition, two-dimensional analysis and fluorography of newly synthesized secretory proteins discharged by these cells in response to carbamylcholine revealed the presence of Mr 24,000 protein and 19 other secretory proteins characteristic of this tumor. The culture system utilizing STBM and supplemented chemically defined medium should allow investigation of the effects of a variety of factors on morphogenesis, cytodifferentiation, and gene expression in pancreatic acinar tumors.

  6. Applied Developmental Biology: Making Human Pancreatic Beta Cells for Diabetics.

    PubMed

    Melton, Douglas A

    2016-01-01

    Understanding the genes and signaling pathways that determine the differentiation and fate of a cell is a central goal of developmental biology. Using that information to gain mastery over the fates of cells presents new approaches to cell transplantation and drug discovery for human diseases including diabetes.

  7. Coating nanofiber scaffolds with beta cell membrane to promote cell proliferation and function

    NASA Astrophysics Data System (ADS)

    Chen, Wansong; Zhang, Qiangzhe; Luk, Brian T.; Fang, Ronnie H.; Liu, Younian; Gao, Weiwei; Zhang, Liangfang

    2016-05-01

    The cell membrane cloaking technique has emerged as an intriguing strategy in nanomaterial functionalization. Coating synthetic nanostructures with natural cell membranes bestows the nanostructures with unique cell surface antigens and functions. Previous studies have focused primarily on development of cell membrane-coated spherical nanoparticles and the uses thereof. Herein, we attempt to extend the cell membrane cloaking technique to nanofibers, a class of functional nanomaterials that are drastically different from nanoparticles in terms of dimensional and mechanophysical characteristics. Using pancreatic beta cells as a model cell line, we demonstrate successful preparation of cell membrane-coated nanofibers and validate that the modified nanofibers possess an antigenic exterior closely resembling that of the source beta cells. When such nanofiber scaffolds are used to culture beta cells, both cell proliferation rate and function are significantly enhanced. Specifically, glucose-dependent insulin secretion from the cells is increased by near five-fold compared with the same beta cells cultured in regular, unmodified nanofiber scaffolds. Overall, coating cell membranes onto nanofibers could add another dimension of flexibility and controllability in harnessing cell membrane functions and offer new opportunities for innovative applications.

  8. Protective effect of Mimosa pudica L. in an L-arginine model of acute necrotising pancreatitis in rats.

    PubMed

    Kaur, Jagdeep; Sidhu, Shabir; Chopra, Kanwaljit; Khan, M U

    2016-07-01

    Mimosa pudica is used in traditional medicine for treating various disorders such as inflammatory conditions, diarrhoea, insomnia, alopecia, urogenital infections and wounds. The present study investigated the effect of M. pudica extract (MPE) on L-arginine-induced acute necrotising pancreatitis in rats. The ethanolic extract of M. pudica leaves was studied for the presence of quercetin and gallic acid using high-performance liquid chromatography. Four groups were employed-normal control rats, L-arginine control rats (two intraperitoneal [i.p.] injections of 2 g/kg at an interval of 1 h), MPE-treated rats (400 mg/kg orally) and melatonin-treated rats (positive control 10 mg/kg i.p.), which were further divided into subgroups according to time points (24 h, 3 days and 14 days). Serum amylase, lipase, tumour necrosis factor-α (TNF-α), pancreatic amylase, nucleic acid content, protein, transforming growth factor-β1 (TGF-β1), thiobarbituric reactive substances, glutathione, nitrite/nitrate, collagen content and histopathological examination were carried out. MPE significantly improved acute necrotising pancreatitis by modulating diagnostic markers of pancreatitis such as serum lipase and pancreatic amylase, inflammation (TNF-α), and oxidative and nitrosative stress. Moreover, MPE administration induced regenerative changes in the pancreas evidenced by increased levels of pancreatic proteins, nucleic acid content and histopathology report. In addition, MPE improved TGF-β1 and collagen levels thereby preventing fibrosis. The current investigation indicates the novel role of MPE in reducing the severity of acute necrotising pancreatitis by plausible mechanisms such as anti-inflammatory and anti-fibrotic activity and by promoting repair and regeneration of the pancreas.

  9. The effect of maternal caffeine ingestion on pancreatic function in the neonatal rat.

    PubMed

    Dunlop, M; Larkins, R G; Court, J M

    1982-10-01

    Pancreatic function was investigated in neonatal suckling offspring of caffeine-ingesting dams, with or without maternal sucrose supplementation, throughout pregnancy and lactation. In offspring of rats ingesting caffeine without sucrose supplementation, there was initial hyperinsulinaemia, followed by a progressive fall of plasma insulin to subnormal levels. This fall in plasma insulin coincided with depletion of pancreatic insulin stores. Both the fall in plasma insulin and depletion of pancreatic insulin stores were prevented by sucrose supplementation of caffeine-ingesting dams. Offspring of dams fed sucrose alone and control offspring also maintained pancreatic insulin stores and circulating insulin levels over the first 14 days of postnatal life. Pancreases from offspring of caffeine-exposed animals tested in vitro showed enhanced sensitivity of the insulin release process to glucose. This was reflected in the glucose concentration required to elicit half-maximal insulin release (2.4 +/- 0.2 mmol/l for caffeine offspring, 2.3 +/- 0.2 mmol/l for caffeine with sucrose, 3.8 +/- 0.3 mmol/l for sucrose and 4.1 +/- 0.3 mmol/l for control offspring, mean +/- SEM). In contrast, offspring of sucrose-supplemented (with or without caffeine) dams showed increased sensitivity of the proinsulin biosynthetic process to glucose, whereas offspring of dams ingesting caffeine alone showed no significant enhancement of the biosynthetic process compared with control offspring. Thus enhanced sensitivity of the insulin secretory process to glucose without a change in the sensitivity of the biosynthetic process in the offspring of the caffeine ingesting (non-sucrose supplemented) dams could explain the progressive depletion of pancreatic insulin stores and eventual hypoinsulinaemia seen in this group.

  10. Soluble complement receptor 1 preserves endothelial barrier function and microcirculation in postischemic pancreatitis in the rat.

    PubMed

    von Dobschuetz, E; Bleiziffer, O; Pahernik, S; Dellian, M; Hoffmann, T; Messmer, K

    2004-05-01

    Components of the activated complement cascade are considered to play a pivotal role in ischemia-reperfusion-induced organ injury. With the use of intravital epifluorescence microscopy, we investigated the effect of complement inhibition by the recombinant soluble complement receptor 1 (sCR1; TP10) on the effect of macromolecular microvascular permeability, functional capillary perfusion, and leukocyte endothelium interaction in postischemic pancreatitis. Anaesthetized Sprague-Dawley rats were subjected to 60 min of normothermic pancreatic ischemia induced by microclipping of the blood-supplying arteries of the organ. Rats who received sCR1 (15 mg/kg body wt iv; n = 7) during reperfusion showed a significant reduction of permeability (1.77 +/- 1.34 x 10(-8) cm/s; n = 7) of tetramethylrhodamine isothiocyanate-labeled albumin injected 90 min after the onset of reperfusion compared with vehicle-treated animals (6.95 +/- 1.56 x 10(-8) cm/s; n = 7). At 120 min after the onset of reperfusion, the length of red blood cell-perfused capillaries (functional capillary density) was significantly improved (from 279 +/- 15.7 to 330 +/- 3.7 cm(-1); n = 7) and the number of leukocytes adherent to postcapillary venules was significantly reduced (from 314 +/- 87 to 163 +/- 71 mm(-2); n = 7) by sCR1 compared with vehicle treatment. Complement inhibition by sCR1 effectively ameliorates pancreatic ischemia-reperfusion-induced microcirculatory disturbances and might be considered for treatment of postischemic pancreatitis.

  11. Protective effects of sivelestat in a caerulein-induced rat acute pancreatitis model.

    PubMed

    Cao, Jun; Liu, Quanyan

    2013-12-01

    In the present study, we investigated the protective effects of sivelestat on acute pancreatitis (AP) in a rat model. Sivelestat is a specific neutrophil elastase inhibitor, which has been developed in Japan in 1991. Varying doses of sivelestat in normal saline were infused continuously in sivelestat-treated groups through osmotic pumps. Blood and pancreas samples were collected for serological and histopathological studies, and ten rats in each group were taken for survival observation. Increasing doses of sivelestat inhibits the expression of lipase, amylase, corticosterone, IL-1β, TNF-α, and nuclear factor-κB. Furthermore, sivelestat reduces the inflammatory cells infiltration, histological damage, and mortality rate. Meanwhile, the total antioxidant power and serum level of IL-4 in high-dose sivelestat-treated groups were increased. Our findings suggest that the increasing doses of sivelestat protect against caerulein-induced AP in rats, and this protection is possibly associated with the anti-inflammatory ability of sivelestat.

  12. Bone marrow (BM) transplantation promotes beta-cell regeneration after acute injury through BM cell mobilization.

    PubMed

    Hasegawa, Yutaka; Ogihara, Takehide; Yamada, Tetsuya; Ishigaki, Yasushi; Imai, Junta; Uno, Kenji; Gao, Junhong; Kaneko, Keizo; Ishihara, Hisamitsu; Sasano, Hironobu; Nakauchi, Hiromitsu; Oka, Yoshitomo; Katagiri, Hideki

    2007-05-01

    There is controversy regarding the roles of bone marrow (BM)-derived cells in pancreatic beta-cell regeneration. To examine these roles in vivo, mice were treated with streptozotocin (STZ), followed by bone marrow transplantation (BMT; lethal irradiation and subsequent BM cell infusion) from green fluorescence protein transgenic mice. BMT improved STZ-induced hyperglycemia, nearly normalizing glucose levels, with partially restored pancreatic islet number and size, whereas simple BM cell infusion without preirradiation had no effects. In post-BMT mice, most islets were located near pancreatic ducts and substantial numbers of bromodeoxyuridine-positive cells were detected in islets and ducts. Importantly, green fluorescence protein-positive, i.e. BM-derived, cells were detected around islets and were CD45 positive but not insulin positive. Then to examine whether BM-derived cell mobilization contributes to this process, we used Nos3(-/-) mice as a model of impaired BM-derived cell mobilization. In streptozotocin-treated Nos3(-/-) mice, the effects of BMT on blood glucose, islet number, bromodeoxyuridine-positive cells in islets, and CD45-positive cells around islets were much smaller than those in streptozotocin-treated Nos3(+/+) controls. A series of BMT experiments using Nos3(+/+) and Nos3(-/-) mice showed hyperglycemia-improving effects of BMT to correlate inversely with the severity of myelosuppression and delay of peripheral white blood cell recovery. Thus, mobilization of BM-derived cells is critical for BMT-induced beta-cell regeneration after injury. The present results suggest that homing of donor BM-derived cells in BM and subsequent mobilization into the injured periphery are required for BMT-induced regeneration of recipient pancreatic beta-cells.

  13. Thyrotropin-releasing hormone (TRH) reverses hyperglycemia in rat

    SciTech Connect

    Luo Luguang Luo, John Z.Q. Jackson, Ivor M.D.

    2008-09-12

    Hyperglycemia in thyrotropin-releasing hormone (TRH) null mice indicates that TRH is involved in the regulation of glucose homeostasis. Further, TRH levels in the pancreas peak during the stages of late embryonic and early neonatal {beta} cell development. These observations are consistent in linking TRH to islet cell proliferation and differentiation. In this study, we examined the effect of TRH administration in damaged pancreatic rat (streptozotocin, STZ) to determine whether TRH could improve damaged pancreatic {beta} cells function. We hypothesize that TRH is able to reverse STZ-induced hyperglycemia by increasing pancreatic islet insulin content, preventing apoptosis, and potentially induce islet regeneration. It was found that following intra-peritoneal (ip) injection, TRH (10 {mu}g/kg body weight (bwt)) reverses STZ (65 mg/kg bwt)-induced hyperglycemia (TRH given 3 days after STZ injection). Increased circulating insulin levels and insulin content in extracted pancreas suggests that TRH reversed STZ-induced hyperglycemia through improving pancreatic islet {beta} cell function. Further studies show a significantly lower level of apoptosis in islets treated with TRH as well as the presence of proliferation marker nestin and Brdu, suggesting that the TRH has the potential to prevent apoptosis and stimulate islet proliferation.

  14. Canine adipose tissue-derived mesenchymal stem cells ameliorate severe acute pancreatitis by regulating T cells in rats

    PubMed Central

    Kim, Hyun-Wook; Song, Woo-Jin; Li, Qiang; Han, Sei-Myoung; Jeon, Kee-Ok; Park, Sang-Chul; Ryu, Min-Ok; Chae, Hyung-Kyu; Kyeong, Kweon

    2016-01-01

    Severe acute pancreatitis (SAP) is associated with systemic complications and high mortality rate in dogs. Mesenchymal stem cells (MSCs) have been investigated for their therapeutic potential in several inflammation models. In the present study, the effects of canine adipose tissue-derived (cAT)-MSCs in a rat model of SAP induced by retrograde injection of 3% sodium taurocholate solution into the pancreatic duct were investigated. cAT-MSCs labeled with dioctadecyl-3,3,3′-tetramethylindo-carbocyanine perchlorate (1 × 107 cells/kg) were systemically administered to rats and pancreatic tissue was collected three days later for histopathological, quantitative real-time polymerase chain reaction, and immunocytochemical analyses. Greater numbers of infused cAT-MSCs were detected in the pancreas of SAP relative to sham-operated rats. cAT-MSC infusion reduced pancreatic edema, inflammatory cell infiltration, and acinar cell necrosis, and decreased pancreatic expression of the pro-inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-1β, -6, -12, -17, and -23 and interferon-γ, while stimulating expression of the anti-inflammatory cytokines IL-4 and IL-10 in SAP rats. Moreover, cAT-MSCs decreased the number of clusters of differentiation 3-positive T cells and increased that of forkhead box P3-positive T cells in the injured pancreas. These results indicate that cAT-MSCs can be effective as a cell-based therapeutic strategy for treatment of SAP in dogs. PMID:27297425

  15. Cyclin C stimulates β-cell proliferation in rat and human pancreatic β-cells

    PubMed Central

    Jiménez-Palomares, Margarita; López-Acosta, José Francisco; Villa-Pérez, Pablo; Moreno-Amador, José Luis; Muñoz-Barrera, Jennifer; Fernández-Luis, Sara; Heras-Pozas, Blanca; Perdomo, Germán; Bernal-Mizrachi, Ernesto

    2015-01-01

    Activation of pancreatic β-cell proliferation has been proposed as an approach to replace reduced functional β-cell mass in diabetes. Quiescent fibroblasts exit from G0 (quiescence) to G1 through pRb phosphorylation mediated by cyclin C/cdk3 complexes. Overexpression of cyclin D1, D2, D3, or cyclin E induces pancreatic β-cell proliferation. We hypothesized that cyclin C overexpression would induce β-cell proliferation through G0 exit, thus being a potential therapeutic target to recover functional β-cell mass. We used isolated rat and human islets transduced with adenovirus expressing cyclin C. We measured multiple markers of proliferation: [3H]thymidine incorporation, BrdU incorporation and staining, and Ki67 staining. Furthermore, we detected β-cell death by TUNEL, β-cell differentiation by RT-PCR, and β-cell function by glucose-stimulated insulin secretion. Interestingly, we have found that cyclin C increases rat and human β-cell proliferation. This augmented proliferation did not induce β-cell death, dedifferentiation, or dysfunction in rat or human islets. Our results indicate that cyclin C is a potential target for inducing β-cell regeneration. PMID:25564474

  16. Characterization of a Commercial Silicon Beta Cell

    SciTech Connect

    Foxe, Michael P.; Hayes, James C.; Mayer, Michael F.; McIntyre, Justin I.; Sivels, Ciara B.; Suarez, Rey

    2016-03-31

    Silicon detectors are of interest for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) due to their enhanced energy resolution compared to plastic scintillators beta cells. Previous work developing a figure-of-merit (FOM) for comparison of beta cells suggests that the minimum detectable activity (MDA) could be reduced by a factor of two to three with the use of silicon detectors. Silicon beta cells have been developed by CEA (France) and Lares Ltd. (Russia), with the PIPSBox developed by CEA being commercially available from Canberra for approximately $35k, but there is still uncertainty about the reproducibility of the capabilities in the field. PNNL is developing a high-resolution beta-gamma detector system in the shallow underground laboratory, which will utilize and characterize the operation of the PIPSBox detector. Throughout this report, we examine the capabilities of the PIPSBox as developed by CEA. The lessons learned through the testing and use of the PIPSBox will allow PNNL to strategically develop a silicon detector optimized to better suit the communities needs in the future.

  17. Phosphorylation events implicating p38 and PI3K mediate tungstate-effects in MIN6 beta cells.

    PubMed

    Piquer, Sandra; Barceló-Batllori, Sílvia; Julià, Marta; Marzo, Nuria; Nadal, Belen; Guinovart, Joan J; Gomis, Ramon

    2007-06-29

    Oral administration of sodium tungstate is an effective treatment for diabetes in animal models. Several lines of evidence indicate the pancreatic beta cell as one of the targets of tungstate action. Here, we examined the molecular mechanism by which this compound exerts its effects on the beta cell line MIN6. Tungstate treatment induced phosphorylation and subsequent activation of p38 and PI3K which in turn are implicated in tungstate PDX-1 nuclear localization and activation. Although no effect was observed in glucose-induced insulin secretion we found that tungstate activates basal insulin release, a process driven, at least in part, by activation of p38. These results show a direct involvement of p38 and PI3K phosphorylation in the mechanism of action of tungstate in the beta cell.

  18. Phosphorylation events implicating p38 and PI3K mediate tungstate-effects in MIN6 beta cells

    SciTech Connect

    Piquer, Sandra; Gomis, Ramon . E-mail: rgomis@clinic.ub.es

    2007-06-29

    Oral administration of sodium tungstate is an effective treatment for diabetes in animal models. Several lines of evidence indicate the pancreatic beta cell as one of the targets of tungstate action. Here, we examined the molecular mechanism by which this compound exerts its effects on the beta cell line MIN6. Tungstate treatment induced phosphorylation and subsequent activation of p38 and PI3K which in turn are implicated in tungstate PDX-1 nuclear localization and activation. Although no effect was observed in glucose-induced insulin secretion we found that tungstate activates basal insulin release, a process driven, at least in part, by activation of p38. These results show a direct involvement of p38 and PI3K phosphorylation in the mechanism of action of tungstate in the beta cell.

  19. Short-term cholinergic desensitization of rat pancreatic secretory response

    SciTech Connect

    Asselin, J.; Larose, L.; Morisset, J.

    1987-03-01

    Dispersed pancreatic acini were first exposed to carbamylcholine (10/sup -7/-10/sup -4/ M) for 60 min, washed, and reexposed to this same agonist (10/sup -8/-10/sup -3/ M) for 15 min. During this second incubation, the functional secretory capacity of these acini was evaluated by measuring amylase release. Acini preexposed to concentrations of carbamylcholine of 10/sup -6/ M or greater showed shifts to the right in the subsequent carbamylcholine dose-response curves of amylase release. A 3-h recovery period (without carbamylcholine) did not restore the altered carbamylcholine dose-response curve. Ca/sup 2 +/ concentrations of 10/sup -7/ M or 2.5 x 10/sup -3/ M instead of 0.5 x 10/sup -3/ M during the 60-min preincubation did not affect the desensitization process. With use of N-(/sup 3/H)methylscopolamine to evaluate muscarinic receptors, the only changes observed after desensitization were a significant decrease in the high-affinity and an equivalent increase in that of the low-affinity receptors. After cholinergic exposure amylase release stimulated by caerulein was only slightly modified, whereas amylase release in response to a phorbol ester 12-O-tetradecanoylphorbol-13-acetate and to the ionophore A23187 was not altered. These data indicate that short-term desensitization with a cholinergic agent is relatively specific to muscarinic agonists, causes changes in the muscarinic receptor high-and low-affinity concentration but does not alter intracellular steps after calcium mobilization or protein kinase C activation known to be involved in the secretion process.

  20. Protective and curative effects of Cocos nucifera inflorescence on alloxan-induced pancreatic cytotoxicity in rats

    PubMed Central

    Renjith, Raveendran S.; Rajamohan, Thankappan

    2012-01-01

    Objectives: This study was planned to investigate the effects of pre and post-treatment of young inflorescence of Cocos nucifera (CnI) on alloxan-induced diabetic rats. Materials and Methods: Male albino Sprague Dawely rats were divided into five groups of six animals each. Group I was normal control, Group II was diabetic control, Cocos nucifera Inflorescence (CnI) was fed along with diet [20% (w/w)] orally (Group III) for a period of 11 days prior to alloxan injection (150 mg/kg i.p.). The curative effect of CnI was evaluated at the same feeding levels in alloxan-induced diabetic rats (Group IV) for a period of 30 days. The effects of both pretreatment and post-treatment (Group V) were also evaluated. Biochemical parameters such serum glucose, hepatic glycogen, and enzymes involving carbohydrate metabolism (hexokinase, phosphoglucomutase, pyruvate kinase, glucose-6-phosphatase, fructose 1, 6-diphosphatase, glucose-6 phosphate dehydrogenase, and glycogen phosphorylase) were assayed along with pancreatic histopathology. Data were analyzed using one-way analysis of variance followed by Duncan's post hoc multiple variance test. P < 0.05 was considered statistical significant. Results: Diabetic control rats showed significant increase in serum glucose (P < 0.05) and decrease in hepatic glycogen levels (P < 0.05) compared to normal rats, which was reversed to near normal in both CnI pretreated and post-treated rats. Treatment with CnI resulted in significant decrease (P < 0.05) in activities of gluconeogenic enzymes in Group III and IV on compared to the diabetic control group, while glycolytic enzyme activities were improved in these groups. The cytotoxicity of pancreatic islets also ameliorated by treatment with CnI on histopathological examination. Conclusion: The results obtained in the study indicate the protective and curative effects of CnI on alloxan-induced pancreatic cytotoxicity, which is mediated through the regulation of carbohydrate metabolic enzyme

  1. Immune Interventions to Preserve Beta Cell Function in Type 1 Diabetes

    PubMed Central

    Ehlers, Mario R.

    2015-01-01

    Type 1 diabetes (T1D) is a chronic autoimmune disease that leads to destruction of pancreatic beta cells, lifelong dependence on insulin, and increased morbidity and mortality from diabetes-related complications. Preservation of residual beta cells at diagnosis is a major goal because higher levels of endogenous insulin secretion are associated with better short- and long-term outcomes. Over the past 3 decades, a variety of immune interventions have been evaluated in the setting of new-onset T1D, including nonspecific immunosuppression, pathway-specific immune modulation, antigen-specific therapies, and cellular therapies. To date, no single intervention has produced durable remission off-therapy in the majority of treated patients, but the field has gained valuable insights into disease mechanisms and potential immunologic correlates of success. In particular, T cell-directed therapies, including therapies that lead to partial depletion or modulation of effector T (Teff) cells and preservation or augmentation of regulatory T (Treg) cells, have shown the most success and will likely form the backbone of future approaches. The next phase will see evaluation of rational combinations, comprising one or more of the following: a Teff-depleting or modulating drug, a cytokine-based tolerogenic (Treg-promoting) agent, and an antigen-specific component. The long-term goal is to reestablish immunologic tolerance to beta cells, thereby preserving residual beta cells early after diagnosis or enabling restoration of beta cell mass from autologous stem cells or induced neogenesis in patients with established T1D. PMID:26225763

  2. Automated insulin granule segmentation from electron photomicrographs of rat pancreatic β-cells

    NASA Astrophysics Data System (ADS)

    McClanahan, Timothy P.; Straub, Susanne G.; Sharp, Geoffrey W. G.; Loew, Murray

    2005-04-01

    Increased blood glucose stimulates pancreatic β-cells and induces an exocytotic release of insulin. The β-cell, which contains ~10^4 insulin-containing granules, releases only a few percent of the granules during a given stimulus such as a meal. The temporal response function to a square wave increase in the concentration of glucose is characteristically biphasic. It is not known whether the granules exhibit random or directed migration patterns as a function of phase. Directed migration would suggest the development of an intracellular gradient directing the path and velocity of insulin granule movement. Our ongoing research investigates this process using manual morphometric analysis of electron micrographs of rat pancreatic β-cells. This is a tedious and time-consuming stereological process. Consequently, we have developed an automated algorithm for accurately segmenting and deriving granule counts, areas, and measuring distance to the plasma membrane. The method is a data-driven image processing approach that implements Mahalanobis classifiers to hierarchically classify pixel candidates and subsequently pixel aggregates as insulin granules. Granule cores and halos are classified independently and fused by intersecting the convex difference of granule halos with core candidates. Once fused, total and individual granule areas and distance metrics to the β-cell plasma membrane are obtained. This algorithm provides a rapid and accurate method for the determination of granule numbers, location, and potential gradients in the pancreatic β-cell under different experimental conditions.

  3. Effect of short- and long-term alcohol feeding in rats on pancreatic enzyme content and enzyme secretion in isolated pancreatic lobules in vitro.

    PubMed

    Bode, C; Dürr, H K; Bode, J C

    1986-07-01

    The effect of short- and long-term ethanol intake on digestive enzyme secretion was determined in isolated pancreatic lobules of rats. Groups of male Wistar rats were fed a modified Lieber-DeCarli diet containing either 5% (w/v) of ethanol, isocaloric amounts of a liquid diet in which ethanol was substituted by starch, or solid rat chow; for 3 days, 1, 2, 4, 8 and 12 weeks. Basal and caerulein-stimulated secretion of lipase, amylase, chymotrypsin and trypsin and the enzyme content in the tissue were studied. Feeding the liquid control diet decreased the tissue content of the four enzymes as compared with the values obtained in the group receiving solid rat chow. While basal and stimulated amylase secretion was markedly reduced in the former group, the secretion pattern of the other enzymes exhibited only transient changes. Caerulein-stimulated secretion of lipase and the proteases was increased by ethanol, the effect being more pronounced during the initial phase of the experiment. Alcohol feeding stimulated the basal secretion of these enzymes only in weeks 1-4. In contrast to the other enzymes, basal and stimulated amylase secretion was not enhanced by ethanol feeding. The results suggest that the enzyme secretion of the rat pancreas is distinctly altered by chronic ethanol feeding. However, the response of the pancreatic enzymes is non-parallel, and changes with the duration of alcohol intake.

  4. QUANTITATIVE ASSESSMENT OF BETA CELL APOPTOSIS AND CELL COMPOSITION OF ISOLATED, UNDISRUPTED HUMAN ISLETS BY LASER SCANNING CYTOMETRY

    PubMed Central

    Todorov, Ivan; Nair, Indu; Avakian-Mansoorian, Alina; Rawson, Jeffrey; Omori, Keiko; Ito, Taihei; Valiente, Luis; Iglesias-Meza, Itzia; Orr, Chris; Shiang, Keh D.; Ferreri, Kevin; Al-Abdullah, Ismail H.; Mullen, Yoko; Kandeel, Fouad

    2010-01-01

    Background Assays for assessing human islet cell quality which provide results prior to transplantation would be very beneficial to improving outcomes for islet transplantation therapy. Parameters such as percent beta cell apoptosis and cell composition are found to vary markedly between different islet preparations, and may serve as markers of islet quality. We have developed fluorescence-based assays using laser scanning cytometry (LSC) for assessing beta cell apoptosis and islet cell composition on serial sections of intact isolated islets. Methods Isolated human islets were fixed in formalin and embedded in paraffin. Serial sections were immunostained for the pancreatic hormones, acinar and ductal cell markers. DNA fragmentation was used to label apoptotic cells. Stained cells were quantified using an iCys laser scanning cytometer. Results Islet preparations from 102 human pancreatic islet isolations were analyzed. For the whole set of islet preparations we found a mean islet cell composition of 54.5±1.2% insulin positive; 33.9±1.2% glucagon; 12.1±0.7% somatostatin and 1.5±0.2% pancreatic polypeptide positive cells. The apoptotic beta cells were 2.85±0.4% with a range of 0.27% to 18.3%. The percentage of apoptotic beta cells correlated well (p<0.0001, n=59) with results obtained in vivo by transplantation of the corresponding islets in diabetic NODscid mice. Conclusions The analysis of whole, non-dissociated islets for cell composition and beta cell apoptosis using LSC is giving reliable and reproducible results and could be done both before islet transplantation, as well as on preserved cell blocks at any future time. Thus, they can be a powerful tool for islet quality assessment. PMID:20697327

  5. Hydrogen-rich saline ameliorates the severity of L-arginine-induced acute pancreatitis in rats

    SciTech Connect

    Chen, Han; Sun, Yan Ping; Li, Yang; Liu, Wen Wu; Xiang, Hong Gang; Fan, Lie Ying; Sun, Qiang; Xu, Xin Yun; Cai, Jian Mei; Ruan, Can Ping; Su, Ning; Yan, Rong Lin; Sun, Xue Jun; Wang, Qiang

    2010-03-05

    Molecular hydrogen, which reacts with the hydroxyl radical, has been considered as a novel antioxidant. Here, we evaluated the protective effects of hydrogen-rich saline on the L-arginine (L-Arg)-induced acute pancreatitis (AP). AP was induced in Sprague-Dawley rats by giving two intraperitoneal injections of L-Arg, each at concentrations of 250 mg/100 g body weight, with an interval of 1 h. Hydrogen-rich saline (>0.6 mM, 6 ml/kg) or saline (6 ml/kg) was administered, respectively, via tail vein 15 min after each L-Arg administration. Severity of AP was assessed by analysis of serum amylase activity, pancreatic water content and histology. Samples of pancreas were taken for measuring malondialdehyde and myeloperoxidase. Apoptosis in pancreatic acinar cell was determined with terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling technique (TUNEL). Expression of proliferating cell nuclear antigen (PCNA) and nuclear factor kappa B (NF-{kappa}B) were detected with immunohistochemistry. Hydrogen-rich saline treatment significantly attenuated the severity of L-Arg-induced AP by ameliorating the increased serum amylase activity, inhibiting neutrophil infiltration, lipid oxidation and pancreatic tissue edema. Moreover, hydrogen-rich saline treatment could promote acinar cell proliferation, inhibit apoptosis and NF-{kappa}B activation. These results indicate that hydrogen treatment has a protective effect against AP, and the effect is possibly due to its ability to inhibit oxidative stress, apoptosis, NF-{kappa}B activation and to promote acinar cell proliferation.

  6. Alcohol oxidizing enzymes and ethanol-induced cytotoxicity in rat pancreatic acinar AR42J cells.

    PubMed

    Bhopale, Kamlesh K; Falzon, Miriam; Ansari, G A S; Kaphalia, Bhupendra S

    2014-04-01

    Alcoholic chronic pancreatitis (ACP) is a serious inflammatory disease causing significant morbidity and mortality. Due to lack of a suitable animal model, the underlying mechanism of ACP is poorly understood. Chronic alcohol abuse inhibits alcohol dehydrogenase (ADH) and facilitates nonoxidative metabolism of ethanol to fatty acid ethyl esters (FAEEs) in the pancreas frequently damaged during chronic ethanol abuse. Earlier, we reported a concentration-dependent formation of FAEEs and cytotoxicity in ethanol-treated rat pancreatic tumor (AR42J) cells, which express high FAEE synthase activity as compared to ADH and cytochrome P450 2E1. Therefore, the present study was undertaken to investigate the role of various ethanol oxidizing enzymes in ethanol-induced pancreatic acinar cell injury. Confluent AR42J cells were pre-treated with inhibitors of ADH class I and II [4-methylpyrazole (MP)] or class I, II, and III [1,10-phenanthroline (PT)], cytochrome P450 2E1 (trans-1,2-dichloroethylene) or catalase (sodium azide) followed by incubation with 800 mg% ethanol at 37°C for 6 h. Ethanol metabolism, cell viability, cytotoxicity (apoptosis and necrosis), cell proliferation status, and formation of FAEEs in AR42J cells were measured. The cell viability and cell proliferation rate were significantly reduced in cells pretreated with 1,10-PT + ethanol followed by those with 4-MP + ethanol. In situ formation of FAEEs was twofold greater in cells incubated with 1,10-PT + ethanol and ∼1.5-fold in those treated with 4-MP + ethanol vs. respective controls. However, cells treated with inhibitors of cytochrome P450 2E1 or catalase in combination of ethanol showed no significant changes either for FAEE formation, cell death or proliferation rate. Therefore, an impaired ADH class I-III catalyzed oxidation of ethanol appears to be a key contributing factor in ethanol-induced pancreatic injury via formation of nonoxidative metabolites of ethanol.

  7. Na+/HCO3- cotransporter is expressed on β and α cells during rat pancreatic development

    PubMed Central

    Cao, Li-Hua; Xia, Cheng-Cai; Shi, Zhao-Chun; Wang, Ning; Gu, Zheng-Hua; Yu, Li-Zhi; Wan, Qi; De, Wei

    2016-01-01

    AIM To determine the expression and localization of the electrogenic Na+/HCO3- cotransporter (NBC1) in rat pancreas during development. METHODS The rat pancreas from postnatal and embryos removed from the uterus of pregnant rats that had been sacrificed by CO2 asphyxiation were used. Rat pancreas from embryonic day (E) 15.5 and E18.5 rat embryos was isolated under a stereomicroscope. Rat pancreas from postnatal (P) days 0, 7, 14, 21 and adult was directly isolated by the unaided eye. The RT-PCR analysis of the NBC1 specific region on rat pancreas tissues from different developmental stages. The two antibodies which target the NBC1 common COOH-terminal region and NH2-terminal region detected a clear band of about 145 kDa in the Western blot analysis. The localization of NBC1 was examined by immuno-fluorescence detection. RESULTS The results revealed the first peak of NBC1 expression at E18.5 and the second peak at P14. Meanwhile, the low NBC1 expression occurred at P7 and adult stages. Our results demonstrated, for the first time, the presence of NBC1 in the plasma membrane of β and α cells, as well as in the basolateral membrane of acinar cells of the rat pancreas at different stages of development. CONCLUSION The data strongly suggests that NBC1 is diversely expressed in the pancreas at different developmental stages, where it may exert its functions in pancreatic development especially islet cell growth through HCO3- transport and pH regulation. PMID:27920473

  8. Lapacho tea (Tabebuia impetiginosa) extract inhibits pancreatic lipase and delays postprandial triglyceride increase in rats.

    PubMed

    Kiage-Mokua, Beatrice Nyanchama; Roos, Nils; Schrezenmeir, Jürgen

    2012-12-01

    Earlier work in our laboratory indicated that ethanolic extracts of Tabebuia impetiginosa, Arctium lappa L., Calendula officinalis, Helianthus annuus, Linum usitatissimum and L. propolis, inhibit pancreatic lipase in vitro. In a follow-up study we assessed their effects on plasma triglycerides in rats fed on a fatty meal. Extracts, orlistat or only ethanol were given orally to the rats together with the test meal and the rate of increase of postprandial triglycerides was assessed over 4 h. Clearing of the triglycerides from the blood compartment was abolished by inhibiting lipoprotein lipase with Triton WR-1339. Our results showed that out of all the extracts, the bark of Tabebuia impetiginosa led to a significant delay in the postprandial increase of plasma triglycerides. However, lapachol, which is contained in the bark of Tabebuia impetiginosa and soluble in ethanol, had no lipase inhibitory effect in vitro and hence this substance did not seem to mediate the pertinent effect.

  9. Rosiglitazone attenuates the severity of hyperlipidemic severe acute pancreatitis in rats

    PubMed Central

    NIYAZ, BATUR; ZHAO, KAI-LIANG; LIU, LI-MIN; CHEN, CHEN; DENG, WEN-HONG; ZUO, TENG; SHI, QIAO; WANG, WEI-XING

    2013-01-01

    Peroxisome proliferator-activated receptor-γ (PPAR-γ) ligand regulates adipocyte differentiation and insulin sensitivity, and exerts antihyperlipidemic and anti-inflammatory effects. However, the mechanisms by which PPAR-γ ligands affect hyperlipidemia with severe acute pancreatitis (SAP) have not been fully elucidated. The present study investigated the effects of rosiglitazone, a PPAR-γ ligand, on hyperlipidemia with SAP in a rat model. The hyperlipidemia was induced with a high-fat diet and SAP was induced by the administration of sodium taurocholate (TCA). The hyperlipidemia was shown to aggravate the severity of the sodium taurocholate-induced SAP. However, rosiglitazone demonstrated significant antihyperlipidemic and anti-inflammatory effects in the rats with high-lipid diet-induced hyperlipidemia and SAP. PMID:24137303

  10. Protecting Effects of Dexamethasone on Thymus of Rats with Severe Acute Pancreatitis

    PubMed Central

    Xiping, Zhang; Li, Chen; Miao, Lin; Hua, Tian

    2007-01-01

    Purpose. To study the protecting effects of dexamethasone on thymus of rats with severe acute pancreatitis (SAP). Methods. The SAP rats were randomly assigned to the model group and dexamethasone-treated group, the other normal healthy rats were assigned to the sham operation group. The rat survival, thymus pathological changes, apoptotic index, as well as expression levels of NF-κB, P-selectin, Bax, Bcl-2, and Caspase-3 protein of all groups were observed, respectively, at 3 hours, 6 hours, and 12 hours. The contents of amylase and endotoxin in plasma as well as the contents of TNF-α, PLA2, and NO in serum were determined. Results. There was no marked difference between the model group and treated group in survival. The contents of different indexes in blood of treated group were lower than those of the model group to various degrees at different time points. The thymus pathological score was lower in treated group than in model group at 12 hours.The treated group in Caspase-3 protein expression of thymus significantly exceeded the model group at 12 hours. The apoptotic index was significantly higher in treated group than in model group. Conclusion. Dexamethasone has protecting effects on thymus of SAP rats. PMID:18288275

  11. Cysteine string protein (CSP) is an insulin secretory granule-associated protein regulating beta-cell exocytosis.

    PubMed Central

    Brown, H; Larsson, O; Bränström, R; Yang, S N; Leibiger, B; Leibiger, I; Fried, G; Moede, T; Deeney, J T; Brown, G R; Jacobsson, G; Rhodes, C J; Braun, J E; Scheller, R H; Corkey, B E; Berggren, P O; Meister, B

    1998-01-01

    Cysteine string proteins (CSPs) are novel synaptic vesicle-associated protein components characterized by an N-terminal J-domain and a central palmitoylated string of cysteine residues. The cellular localization and functional role of CSP was studied in pancreatic endocrine cells. In situ hybridization and RT-PCR analysis demonstrated CSP mRNA expression in insulin-producing cells. CSP1 mRNA was present in pancreatic islets; both CSP1 and CSP2 mRNAs were seen in insulin-secreting cell lines. Punctate CSP-like immunoreactivity (CSP-LI) was demonstrated in most islets of Langerhans cells, acinar cells and nerve fibers of the rat pancreas. Ultrastructural analysis showed CSP-LI in close association with membranes of secretory granules of cells in the endo- and exocrine pancreas. Subcellular fractionation of insulinoma cells showed CSP1 (34/36 kDa) in granular fractions; the membrane and cytosol fractions contained predominantly CSP2 (27 kDa). The fractions also contained proteins of 72 and 70 kDa, presumably CSP dimers. CSP1 overexpression in INS-1 cells or intracellular administration of CSP antibodies into mouse ob/ob beta-cells did not affect voltage-dependent Ca2+-channel activity. Amperometric measurements showed a significant decrease in insulin exocytosis in individual INS-1 cells after CSP1 overexpression. We conclude that CSP is associated with insulin secretory granules and that CSP participates in the molecular regulation of insulin exocytosis by mechanisms not involving changes in the activity of voltage-gated Ca2+-channels. PMID:9724640

  12. Chop deletion reduces oxidative stress, improves beta cell function, and promotes cell survival in multiple mouse models of diabetes.

    PubMed

    Song, Benbo; Scheuner, Donalyn; Ron, David; Pennathur, Subramaniam; Kaufman, Randal J

    2008-10-01

    The progression from insulin resistance to type 2 diabetes is caused by the failure of pancreatic beta cells to produce sufficient levels of insulin to meet the metabolic demand. Recent studies indicate that nutrient fluctuations and insulin resistance increase proinsulin synthesis in beta cells beyond the capacity for folding of nascent polypeptides within the endoplasmic reticulum (ER) lumen, thereby disrupting ER homeostasis and triggering the unfolded protein response (UPR). Chronic ER stress promotes apoptosis, at least in part through the UPR-induced transcription factor C/EBP homologous protein (CHOP). We assessed the effect of Chop deletion in multiple mouse models of type 2 diabetes and found that Chop-/- mice had improved glycemic control and expanded beta cell mass in all conditions analyzed. In both genetic and diet-induced models of insulin resistance, CHOP deficiency improved beta cell ult