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Khan D, Vasu S, Moffett RC, Gault VA, Flatt PR, Irwin N. Locally produced xenin and the neurotensinergic system in pancreatic islet function and β-cell survival. Biol Chem 2017; 399:79-92. [DOI: 10.1515/hsz-2017-0136] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 08/14/2017] [Indexed: 12/11/2022]
Abstract
AbstractModulation of neuropeptide receptors is important for pancreatic β-cell function. Here, islet distribution and effects of the neurotensin (NT) receptor modulators, xenin and NT, was examined. Xenin, but not NT, significantly improved glucose disposal and insulin secretion, in mice. However, both peptides stimulated insulin secretion from rodent β-cells at 5.6 mmglucose, with xenin having similar insulinotropic actions at 16.7 mmglucose. In contrast, NT inhibited glucose-induced insulin secretion. Similar observations were made in human 1.1B4 β-cells and isolated mouse islets. Interestingly, similar xenin levels were recorded in pancreatic and small intestinal tissue. Arginine and glucose stimulated xenin release from islets. Streptozotocin treatment decreased and hydrocortisone treatment increased β-cell mass in mice. Xenin co-localisation with glucagon was increased by streptozotocin, but unaltered in hydrocortisone mice. This corresponded to elevated plasma xenin levels in streptozotocin mice. In addition, co-localisation of xenin with insulin was increased by hydrocortisone, and decreased by streptozotocin. Furtherin vitroinvestigations revealed that xenin and NT protected β-cells against streptozotocin-induced cytotoxicity. Xenin augmented rodent and human β-cell proliferation, whereas NT displayed proliferative actions only in human β-cells. These data highlight the involvement of NT signalling pathways for the possible modulation of β-cell function.
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Association of TCM body constitution with insulin resistance and risk of diabetes in impaired glucose regulation patients. Altern Ther Health Med 2017; 17:459. [PMID: 28893239 PMCID: PMC5594579 DOI: 10.1186/s12906-017-1964-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 09/01/2017] [Indexed: 12/16/2022]
Abstract
Background Impaired glucose regulation (IGR) patients have increased risk of type 2 diabetes mellitus (T2DM). Identifying relevant risk factors in IGR subjects could facilitate early detection and prevention of IGR progression to diabetes. This study investigated the association between Traditional Chinese Medicine (TCM) body constitution and serum cytokines, and whether body constitution could independently predict diabetes in IGR subjects. Method Patients with IGR (n = 306) received a blood test and their body constitution type was assessed using a body constitution questionnaire (BCQ). Serum levels of cytokines were measured by ELISA. Patients were followed up for at least three years, and their status of diabetes were recorded. Multivariate logistic regression was used to estimate odds ratios (ORs) of diabetes for body constitution. Results Phlegm-damp, Damp-heat and Qi-deficiency were three most common unbanlenced constitutions among IGR subjects. Phlegm-damp and Damp-heat constitution subjects showed higher serum levels of interleukin 6 (IL-6), tumour necrosis factor-α (TNF-α), leptin and lower serum levels of adiponectin (P<0.05). Qi-deficiency constitution subjects showed higher serum levels of leptin and lower serum levels of adiponectin, glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) (P<0.05). Subjects with Phlegm-damp or Damp-heat constitution demonstrated a significantly higher risk of diabetes (P<0.05). Conclusion Phlegm-damp and Damp-heat TCM body constitution are strongly associated with abnormal serum cytokines, and could potentially serve as a predictor of diabetes in IGR subjects. Body constitution can help to identify IGR subjects who are at a high risk of progression to diabetes.
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Millar P, Pathak N, Parthsarathy V, Bjourson AJ, O'Kane M, Pathak V, Moffett RC, Flatt PR, Gault VA. Metabolic and neuroprotective effects of dapagliflozin and liraglutide in diabetic mice. J Endocrinol 2017; 234:255-267. [PMID: 28611211 DOI: 10.1530/joe-17-0263] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 06/13/2017] [Indexed: 12/24/2022]
Abstract
This study assessed the metabolic and neuroprotective actions of the sodium glucose cotransporter-2 inhibitor dapagliflozin in combination with the GLP-1 agonist liraglutide in dietary-induced diabetic mice. Mice administered low-dose streptozotocin (STZ) on a high-fat diet received dapagliflozin, liraglutide, dapagliflozin-plus-liraglutide (DAPA-Lira) or vehicle once-daily over 28 days. Energy intake, body weight, glucose and insulin concentrations were measured at regular intervals. Glucose tolerance, insulin sensitivity, hormone and biochemical analysis, dual-energy X-ray absorptiometry densitometry, novel object recognition, islet and brain histology were examined. Once-daily administration of DAPA-Lira resulted in significant decreases in body weight, fat mass, glucose and insulin concentrations, despite no change in energy intake. Similar beneficial metabolic improvements were observed regarding glucose tolerance, insulin sensitivity, HOMA-IR, HOMA-β, HbA1c and triglycerides. Plasma glucagon, GLP-1 and IL-6 levels were increased and corticosterone concentrations decreased. DAPA-Lira treatment decreased alpha cell area and increased insulin content compared to dapagliflozin monotherapy. Recognition memory was significantly improved in all treatment groups. Brain histology demonstrated increased staining for doublecortin (number of immature neurons) in dentate gyrus and synaptophysin (synaptic density) in stratum oriens and stratum pyramidale. These data demonstrate that combination therapy of dapagliflozin and liraglutide exerts beneficial metabolic and neuroprotective effects in diet-induced diabetic mice. Our results highlight important personalised approach in utilising liraglutide in combination with dapagliflozin, instead of either agent alone, for further clinical evaluation in treatment of diabetes and associated neurodegenerative disorders.
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Affiliation(s)
- Paul Millar
- SAAD Centre for Pharmacy and DiabetesSchool of Biomedical Sciences, University of Ulster, Northern Ireland, UK
| | - Nupur Pathak
- SAAD Centre for Pharmacy and DiabetesSchool of Biomedical Sciences, University of Ulster, Northern Ireland, UK
| | - Vadivel Parthsarathy
- SAAD Centre for Pharmacy and DiabetesSchool of Biomedical Sciences, University of Ulster, Northern Ireland, UK
| | - Anthony J Bjourson
- Northern Ireland Centre for Stratified MedicineUniversity of Ulster, C-TRIC Building, Altnagelvin Hospital, Northern Ireland, UK
| | - Maurice O'Kane
- Northern Ireland Centre for Stratified MedicineUniversity of Ulster, C-TRIC Building, Altnagelvin Hospital, Northern Ireland, UK
- Clinical Chemistry LaboratoryWestern Health and Social Care Trust, Altnagelvin Hospital, Northern Ireland, UK
| | - Varun Pathak
- SAAD Centre for Pharmacy and DiabetesSchool of Biomedical Sciences, University of Ulster, Northern Ireland, UK
| | - R Charlotte Moffett
- SAAD Centre for Pharmacy and DiabetesSchool of Biomedical Sciences, University of Ulster, Northern Ireland, UK
| | - Peter R Flatt
- SAAD Centre for Pharmacy and DiabetesSchool of Biomedical Sciences, University of Ulster, Northern Ireland, UK
| | - Victor A Gault
- SAAD Centre for Pharmacy and DiabetesSchool of Biomedical Sciences, University of Ulster, Northern Ireland, UK
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Hasib A, Ng MT, Gault VA, Khan D, Parthsarathy V, Flatt PR, Irwin N. An enzymatically stable GIP/xenin hybrid peptide restores GIP sensitivity, enhances beta cell function and improves glucose homeostasis in high-fat-fed mice. Diabetologia 2017; 60:541-552. [PMID: 28004148 PMCID: PMC6518372 DOI: 10.1007/s00125-016-4186-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 11/29/2016] [Indexed: 12/12/2022]
Abstract
AIMS/HYPOTHESIS Glucose-dependent insulinotropic polypeptide (GIP) and xenin, regulatory gut hormones secreted from enteroendocrine K cells, exert important effects on metabolism. In addition, xenin potentiates the biological actions of GIP. The present study assessed the actions and therapeutic utility of a (DAla2)GIP/xenin-8-Gln hybrid peptide, in comparison with the parent peptides (DAla2)GIP and xenin-8-Gln. METHODS Following confirmation of enzymatic stability, insulin secretory activity of (DAla2)GIP/xenin-8-Gln was assessed in BRIN-BD11 beta cells. Acute and persistent glucose-lowering and insulin-releasing effects were then examined in vivo. Finally, the metabolic benefits of twice daily injection of (DAla2)GIP/xenin-8-Gln was determined in high-fat-fed mice. RESULTS All peptides significantly (p < 0.05 to p < 0.001) enhanced in vitro insulin secretion from pancreatic clonal BRIN-BD11 cells, with xenin (and particularly GIP)-related signalling pathways, being important for this action. Administration of (DAla2)GIP or (DAla2)GIP/xenin-8-Gln in combination with glucose significantly (p < 0.05) lowered blood glucose and increased plasma insulin in mice, with a protracted response of up to 4 h. All treatments elicited appetite-suppressive effects (p < 0.05), particularly (DAla2)GIP/xenin-8-Gln and xenin-8-Gln at elevated doses of 250 nmol/kg. Twice-daily administration of (DAla2)GIP/xenin-8-Gln or (DAla2)GIP for 21 days to high-fat-fed mice returned circulating blood glucose to lean control levels. In addition, (DAla2)GIP/xenin-8-Gln treatment significantly (p < 0.05) reduced glycaemic levels during a 24 h glucose profile assessment. Neither of the treatment regimens had an effect on body weight, energy intake or circulating insulin concentrations. However, insulin sensitivity was significantly (p < 0.001) improved by both treatments. Interestingly, GIP-mediated glucose-lowering (p < 0.05) and insulin-releasing (p < 0.05 to p < 0.01) effects were substantially improved by (DAla2)GIP and (DAla2)GIP/xenin-8-Gln treatment. Pancreatic islet and beta cell area (p < 0.001), as well as pancreatic insulin content (p < 0.05), were augmented in (DAla2)GIP/xenin-8-Gln-treated mice, related to enhanced proliferation and decreased apoptosis of beta cells, whereas (DAla2)GIP evoked increases (p < 0.05 to p < 0.01) in islet number. CONCLUSIONS/INTERPRETATION These studies highlight the clear potential of GIP/xenin hybrids for the treatment of type 2 diabetes.
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Affiliation(s)
- Annie Hasib
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - Ming T Ng
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - Victor A Gault
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - Dawood Khan
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - Vadivel Parthsarathy
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK.
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Khan D, Vasu S, Moffett RC, Irwin N, Flatt PR. Influence of neuropeptide Y and pancreatic polypeptide on islet function and beta-cell survival. Biochim Biophys Acta Gen Subj 2017; 1861:749-758. [PMID: 28069397 DOI: 10.1016/j.bbagen.2017.01.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 01/06/2023]
Abstract
BACKGROUND In the present study we assessed the impact of neuropeptide Y receptor (NPYR) modulators, neuropeptide Y (NPY) and pancreatic polypeptide (PP), on islet function and beta-cell survival. METHODS The effects of NPY and PP on beta-cell function were examined in BRIN BD11 and 1.1B4 beta-cells, as well as isolated mouse islets. Involvement of both peptides in pancreatic islet adaptations to streptozotocin and hydrocortisone, as well as effects on beta-cell proliferation and apoptosis was also evaluated. RESULTS Neither NPY nor PP affected in vivo glucose disposal or insulin secretion in mice. However, both peptides inhibited (p<0.05 to p<0.001) glucose stimulated insulin secretion from rat and human beta-cells. NPY exerted similar insulinostatic effects in isolated mouse islets. NPY and PP inhibited alanine-induced changes in BRIN BD11 cell membrane potential and (Ca2+)i. Streptozotocin treatment decreased and hydrocortisone treatment increased beta-cell mass in mice. In addition, streptozotocin, but not hydrocortisone, increased PP cell area. Streptozotocin also shifted the normal co-localisation of NPY with PP, towards more pronounced co-expression with somatostatin in delta-cells. Both streptozotocin and hydrocortisone increased pancreatic exocrine expression of NPY. More detailed in vitro investigations revealed that NPY, but not PP, augmented (p<0.01) BRIN BD11 beta-cell proliferation. In addition, both peptides exerted protective effects against streptozotocin-induced DNA damage in beta-cells. CONCLUSION These data emphasise the involvement of PP, and particularly NPY, in the regulation of beta-cell mass and function. GENERAL SIGNIFICANCE Modulation of PP and NPY signalling is suitable for further evaluation and possible clinical development for the treatment of diabetes.
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Affiliation(s)
- Dawood Khan
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - Srividya Vasu
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - R Charlotte Moffett
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK.
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK
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Khan D, Vasu S, Moffett RC, Irwin N, Flatt PR. Islet distribution of Peptide YY and its regulatory role in primary mouse islets and immortalised rodent and human beta-cell function and survival. Mol Cell Endocrinol 2016; 436:102-13. [PMID: 27465830 DOI: 10.1016/j.mce.2016.07.020] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/18/2016] [Accepted: 07/19/2016] [Indexed: 12/25/2022]
Abstract
Recent evidence suggests that the classic gut peptide, Peptide YY (PYY), could play a fundamental role in endocrine pancreatic function. In the present study expression of PYY and its NPY receptors on mouse islets and immortalised rodent and human beta-cells was examined together with the effects of both major circulating forms of PYY, namely PYY(1-36) and PYY(3-36), on beta-cell function, murine islet adaptions to insulin deficiency/resistance, as well as direct effects on cultured beta-cell proliferation and apoptosis. In vivo administration of PYY(3-36), but not PYY(1-36), markedly (p < 0.05) decreased food intake in overnight fasted mice. Neither form of PYY affected glucose disposal or insulin secretion following an i.p. glucose challenge. However, in vitro, PYY(1-36) and PYY(3-36) inhibited (p < 0.05 to p < 0.001) glucose, alanine and GLP-1 stimulated insulin secretion from immortalised rodent and human beta-cells, as well as isolated mouse islets, by impeding alterations in membrane potential, [Ca(2+)]i and elevations of cAMP. Mice treated with multiple low dose streptozotocin presented with severe (p < 0.01) loss of beta-cell mass accompanied by notable increases (p < 0.001) in alpha and PP cell numbers. In contrast, hydrocortisone-induced insulin resistance increased islet number (p < 0.01) and beta-cell mass (p < 0.001). PYY expression was consistently observed in alpha-, PP- and delta-, but not beta-cells. Streptozotocin decreased islet PYY co-localisation with PP (p < 0.05) and somatostatin (p < 0.001), whilst hydrocortisone increased PYY co-localisation with glucagon (p < 0.05) in mice. More detailed in vitro investigations revealed that both forms of PYY augmented (p < 0.05 to p < 0.01) immortalised human and rodent beta-cell proliferation and protected against streptozotocin-induced cytotoxicity, to a similar or superior extent as the well characterised beta-cell proliferative and anti-apoptotic agent GLP-1. Taken together, these data highlight the significance and potential offered by modulation of pancreatic islet NPY receptor signalling pathways for preservation of beta-cell mass in diabetes.
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Affiliation(s)
- Dawood Khan
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK
| | - Srividya Vasu
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK
| | - R Charlotte Moffett
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK
| | - Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK.
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK
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Fava GE, Dong EW, Wu H. Intra-islet glucagon-like peptide 1. J Diabetes Complications 2016; 30:1651-1658. [PMID: 27267264 PMCID: PMC5050074 DOI: 10.1016/j.jdiacomp.2016.05.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 05/14/2016] [Accepted: 05/17/2016] [Indexed: 02/06/2023]
Abstract
PURPOSE Glucagon-like peptide-1 (GLP-1) is originally identified in the gut as an incretin hormone, and it is potent in stimulating insulin secretion in the pancreas. However, increasing evidence suggests that GLP-1 is also produced locally within pancreatic islets. This review focuses on the past and current discoveries regarding intra-islet GLP-1 production and its functions. MAIN FINDINGS There has been a long-standing debate with regard to whether GLP-1 is produced in the pancreatic α cells. Early controversies lead to the widely accepted conclusion that the vast majority of proglucagon is processed to form glucagon in the pancreas, whereas an insignificant amount is cleaved to produce GLP-1. With technological advancements, recent studies have shown that bioactive GLP-1 is produced locally in the pancreas, and the expression and secretion of GLP-1 within islets are regulated by various factors such as cytokines, hyperglycemia, and β cell injury. CONCLUSIONS GLP-1 is produced by the pancreatic α cells, and it is fully functional as an incretin. Therefore, intra-islet GLP-1 may exert insulinotropic and glucagonostatic effects locally via paracrine and/or autocrine actions, under both normal and diabetic conditions.
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Affiliation(s)
- Genevieve E Fava
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States
| | - Emily W Dong
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States
| | - Hongju Wu
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States.
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O'Harte FPM, Ng MT, Lynch AM, Conlon JM, Flatt PR. Dogfish glucagon analogues counter hyperglycaemia and enhance both insulin secretion and action in diet-induced obese diabetic mice. Diabetes Obes Metab 2016; 18:1013-24. [PMID: 27357054 DOI: 10.1111/dom.12713] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/16/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022]
Abstract
AIMS To investigate the antidiabetic actions of three dogfish glucagon peptide analogues [known glucagon-like peptide-1 and glucagon receptor co-agonists] after chronic administration in diet-induced high-fat-diet-fed diabetic mice. MATERIALS AND METHODS National Institutes of Health Swiss mice were pre-conditioned to a high-fat diet (45% fat) for 100 days, and control mice were fed a normal diet (10% fat). Normal diet control and high-fat-fed control mice received twice-daily intraperitoneal (i.p.) saline injections, while the high-fat-fed treatment groups (n = 8) received twice-daily injections of exendin-4(1-39), [S2a]dogfish glucagon, [S2a]dogfish glucagon exendin-4(31-39) or [S2a]dogfish glucagon-Lys(30) -γ-glutamyl-PAL (25 nmol/kg body weight) for 51 days. RESULTS After dogfish glucagon analogue treatment, there was a rapid and sustained decrease in non-fasting blood glucose and an associated insulinotropic effect (analysis of variance, p < .05 to <.001) compared with saline-treated high-fat-fed controls. All peptide treatments significantly improved i.p. and oral glucose tolerance with concomitant increased insulin secretion compared with saline-treated high-fat-fed controls (p <.05 to <.001). After chronic treatment, no receptor desensitization was observed but insulin sensitivity was enhanced for all peptide-treated groups (p < .01 to <.001) except [S2a]dogfish glucagon. Both exendin-4 and [S2a]dogfish glucagon exendin-4(31-39) significantly reduced plasma triglyceride concentrations compared with those found in lean controls (p = .0105 and p = .0048, respectively). Pancreatic insulin content was not affected by peptide treatments but [S2a]dogfish glucagon and [S2a]dogfish glucagon exendin-4(31-39) decreased pancreatic glucagon by 28%-34% (p = .0221 and p = .0075, respectively). The percentage of β-cell area within islets was increased by exendin-4 and peptide analogue treatment groups compared with high-fat-fed controls and the β-cell area decreased (p < .05 to <.01). CONCLUSIONS Overall, dogfish glucagon co-agonist analogues had several beneficial metabolic effects, showing therapeutic potential for type 2 diabetes.
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Affiliation(s)
- F P M O'Harte
- School of Biomedical Sciences, Saad Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, UK.
| | - M T Ng
- School of Biomedical Sciences, Saad Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, UK
| | - A M Lynch
- School of Biomedical Sciences, Saad Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, UK
| | - J M Conlon
- School of Biomedical Sciences, Saad Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, UK
| | - P R Flatt
- School of Biomedical Sciences, Saad Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, UK
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Iida A, Seino Y, Fukami A, Maekawa R, Yabe D, Shimizu S, Kinoshita K, Takagi Y, Izumoto T, Ogata H, Ishikawa K, Ozaki N, Tsunekawa S, Hamada Y, Oiso Y, Arima H, Hayashi Y. Endogenous GIP ameliorates impairment of insulin secretion in proglucagon-deficient mice under moderate beta cell damage induced by streptozotocin. Diabetologia 2016; 59:1533-1541. [PMID: 27053237 PMCID: PMC4901104 DOI: 10.1007/s00125-016-3935-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/02/2016] [Indexed: 01/06/2023]
Abstract
AIMS/HYPOTHESIS The action of incretin hormones including glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) is potentiated in animal models defective in glucagon action. It has been reported that such animal models maintain normoglycaemia under streptozotocin (STZ)-induced beta cell damage. However, the role of GIP in regulation of glucose metabolism under a combination of glucagon deficiency and STZ-induced beta cell damage has not been fully explored. METHODS In this study, we investigated glucose metabolism in mice deficient in proglucagon-derived peptides (PGDPs)-namely glucagon gene knockout (GcgKO) mice-administered with STZ. Single high-dose STZ (200 mg/kg, hSTZ) or moderate-dose STZ for five consecutive days (50 mg/kg × 5, mSTZ) was administered to GcgKO mice. The contribution of GIP to glucose metabolism in GcgKO mice was also investigated by experiments employing dipeptidyl peptidase IV (DPP4) inhibitor (DPP4i) or Gcg-Gipr double knockout (DKO) mice. RESULTS GcgKO mice developed severe diabetes by hSTZ administration despite the absence of glucagon. Administration of mSTZ decreased pancreatic insulin content to 18.8 ± 3.4 (%) in GcgKO mice, but ad libitum-fed blood glucose levels did not significantly increase. Glucose-induced insulin secretion was marginally impaired in mSTZ-treated GcgKO mice but was abolished in mSTZ-treated DKO mice. Although GcgKO mice lack GLP-1, treatment with DPP4i potentiated glucose-induced insulin secretion and ameliorated glucose intolerance in mSTZ-treated GcgKO mice, but did not increase beta cell area or significantly reduce apoptotic cells in islets. CONCLUSIONS/INTERPRETATION These results indicate that GIP has the potential to ameliorate glucose intolerance even under STZ-induced beta cell damage by increasing insulin secretion rather than by promoting beta cell survival.
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Affiliation(s)
- Atsushi Iida
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yusuke Seino
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan.
- Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | - Ayako Fukami
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Ryuya Maekawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Daisuke Yabe
- Yutaka Seino Distinguished Center for Diabetes Research, Kansai Electric Power Medical Research Institute, Kobe, Japan
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shinobu Shimizu
- Yutaka Seino Distinguished Center for Diabetes Research, Kansai Electric Power Medical Research Institute, Kobe, Japan
| | - Keita Kinoshita
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan
| | - Yusuke Takagi
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan
| | - Takako Izumoto
- Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hidetada Ogata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Kota Ishikawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Nobuaki Ozaki
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Shin Tsunekawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yoji Hamada
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
- Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yutaka Oiso
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yoshitaka Hayashi
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan.
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Functionality and antidiabetic utility of β- and L-cell containing pseudoislets. Exp Cell Res 2016; 344:201-9. [DOI: 10.1016/j.yexcr.2016.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 12/12/2022]
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Green AD, Vasu S, Moffett RC, Flatt PR. Co-culture of clonal beta cells with GLP-1 and glucagon-secreting cell line impacts on beta cell insulin secretion, proliferation and susceptibility to cytotoxins. Biochimie 2016; 125:119-25. [DOI: 10.1016/j.biochi.2016.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 03/21/2016] [Indexed: 12/22/2022]
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Omar B, Ahlkvist L, Yamada Y, Seino Y, Ahrén B. Incretin hormone receptors are required for normal beta cell development and function in female mice. Peptides 2016; 79:58-65. [PMID: 27020250 DOI: 10.1016/j.peptides.2016.03.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 03/01/2016] [Accepted: 03/23/2016] [Indexed: 02/07/2023]
Abstract
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 of beta cell function both in vivo and in vitro in a process that appears to be independent of the intestinally secreted incretin hormones. We therefore conclude that the incretin hormones together significantly impact both beta-cell function and beta-cell development.
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Affiliation(s)
- Bilal Omar
- Department of Clinical Sciences, Medicine, Lund University, Sölvegatan 19, 22184 Lund, Sweden.
| | - Linda Ahlkvist
- Department of Clinical Sciences, Medicine, Lund University, Sölvegatan 19, 22184 Lund, Sweden
| | - Yuchiro Yamada
- Graduate School of Medicine, Akita University, Akita, Japan
| | - Yutaka Seino
- Yutaka Seino Distinguished Center for Diabetes Research, Kensai Electric Power Medical Research Institute, Kobe, Japan
| | - Bo Ahrén
- Department of Clinical Sciences, Medicine, Lund University, Sölvegatan 19, 22184 Lund, Sweden
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Linnemann AK, Davis DB. Glucagon-like peptide-1 and cholecystokinin production and signaling in the pancreatic islet as an adaptive response to obesity. J Diabetes Investig 2016; 7 Suppl 1:44-9. [PMID: 27186355 PMCID: PMC4854504 DOI: 10.1111/jdi.12465] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 12/21/2015] [Indexed: 12/22/2022] Open
Abstract
Precise control of blood glucose is dependent on adequate β‐cell mass and function. Thus, reductions in β‐cell mass and function lead to insufficient insulin production to meet demand, and result in diabetes. Recent evidence suggests that paracrine signaling in the islet might be important in obesity, and disruption of this signaling could play a role in the pathogenesis of diabetes. For example, we recently discovered a novel islet incretin axis where glucagon‐like peptide‐1 regulates β‐cell production of another classic gut hormone, cholecystokinin. This axis is stimulated by obesity, and plays a role in enhancing β‐cell survival. In the present review, we place our observations in the wider context of the literature on incretin regulation in the islet, and discuss the potential for therapeutic targeting of these pathways.
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Affiliation(s)
- Amelia K Linnemann
- Department of Medicine Division of Endocrinology University of Wisconsin-Madison Madison Wisconsin USA
| | - Dawn Belt Davis
- Department of MedicineDivision of EndocrinologyUniversity of Wisconsin-MadisonMadisonWisconsinUSA; William S Middleton Memorial Veterans HospitalMadisonWisconsinUSA
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64
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Acute intravenous glucose load impairs early insulin secretion and insulin content in islet β cells in mice. Life Sci 2016; 144:148-55. [DOI: 10.1016/j.lfs.2015.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 11/14/2015] [Accepted: 12/04/2015] [Indexed: 01/04/2023]
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Irwin N, Flatt PR. New perspectives on exploitation of incretin peptides for the treatment of diabetes and related disorders. World J Diabetes 2015; 6:1285-1295. [PMID: 26557956 PMCID: PMC4635139 DOI: 10.4239/wjd.v6.i15.1285] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 09/25/2015] [Accepted: 10/27/2015] [Indexed: 02/05/2023] Open
Abstract
The applicability of stable gut hormones for the treatment of obesity-related diabetes is now undisputable. This is based predominantly on prominent and sustained glucose-lowering actions, plus evidence that these peptides can augment insulin secretion and pancreatic islet function over time. This review highlights the therapeutic potential of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), oxyntomodulin (OXM) and cholecystokinin (CCK) for obesity-related diabetes. Stable GLP-1 mimetics have already been successfully adopted into the diabetic clinic, whereas GIP, CCK and OXM molecules offer promise as potential new classes of antidiabetic drugs. Moreover, recent studies have shown improved therapeutic effects following simultaneous modulation of multiple receptor signalling pathways by combination therapy or use of dual/triple agonist peptides. However, timing and composition of injections may be important to permit interludes of beta-cell rest. The review also addresses the possible perils of incretin based drugs for treatment of prediabetes. Finally, the unanticipated utility of stable gut peptides as effective treatments for complications of diabetes, bone disorders, cognitive impairment and cardiovascular dysfunction is considered.
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Linnemann AK, Neuman JC, Battiola TJ, Wisinski JA, Kimple ME, Davis DB. Glucagon-Like Peptide-1 Regulates Cholecystokinin Production in β-Cells to Protect From Apoptosis. Mol Endocrinol 2015; 29:978-87. [PMID: 25984632 DOI: 10.1210/me.2015-1030] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cholecystokinin (CCK) is a classic gut hormone that is also expressed in the pancreatic islet, where it is highly up-regulated with obesity. Loss of CCK results in increased β-cell apoptosis in obese mice. Similarly, islet α-cells produce increased amounts of another gut peptide, glucagon-like peptide 1 (GLP-1), in response to cytokine and nutrient stimulation. GLP-1 also protects β-cells from apoptosis via cAMP-mediated mechanisms. Therefore, we hypothesized that the activation of islet-derived CCK and GLP-1 may be linked. We show here that both human and mouse islets secrete active GLP-1 as a function of body mass index/obesity. Furthermore, GLP-1 can rapidly stimulate β-cell CCK production and secretion through direct targeting by the cAMP-modulated transcription factor, cAMP response element binding protein (CREB). We find that cAMP-mediated signaling is required for Cck expression, but CCK regulation by cAMP does not require stimulatory levels of glucose or insulin secretion. We also show that CREB directly targets the Cck promoter in islets from obese (Leptin(ob/ob)) mice. Finally, we demonstrate that the ability of GLP-1 to protect β-cells from cytokine-induced apoptosis is partially dependent on CCK receptor signaling. Taken together, our work suggests that in obesity, active GLP-1 produced in the islet stimulates CCK production and secretion in a paracrine manner via cAMP and CREB. This intraislet incretin loop may be one mechanism whereby GLP-1 protects β-cells from apoptosis.
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Affiliation(s)
- Amelia K Linnemann
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Joshua C Neuman
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Therese J Battiola
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Jaclyn A Wisinski
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Michelle E Kimple
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
| | - Dawn Belt Davis
- Department of Medicine (A.K.L., T.J.B., J.A.W., M.E.K., D.B.D.), Division of Endocrinology, University of Wisconsin-Madison, Madison, Wisconsin 53705; Department of Nutritional Sciences (J.C.N.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and William S. Middleton Memorial Veterans Hospital (D.B.D.), Madison, Wisconsin 53705
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Moffett RC, Patterson S, Irwin N, Flatt PR. Positive effects of GLP-1 receptor activation with liraglutide on pancreatic islet morphology and metabolic control in C57BL/KsJ db/db mice with degenerative diabetes. Diabetes Metab Res Rev 2015; 31:248-55. [PMID: 25256010 DOI: 10.1002/dmrr.2608] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 09/11/2014] [Indexed: 12/20/2022]
Abstract
BACKGROUND Stable glucagon-like peptide-1 (GLP-1) mimetics, such as the GLP-1 analogue liraglutide, are approved for treatment of type 2 diabetes. GLP-1 has a spectrum of anti-diabetic effects that are of possible utility in the treatment of more severe forms of diabetes. METHODS The present study has evaluated the effect of once daily liraglutide injection (25 nmol/kg bw) for 15 days on metabolic control, islet architecture, and islet morphology in C57BL/KsJ db/db mice. RESULTS Liraglutide had no appreciable effects on body weight, food intake, and non-fasting glucose and insulin concentrations. However, HbA1c was significantly (p < 0.001) decreased, and oral glucose tolerance improved in liraglutide treated db/db mice. Pancreatic insulin content was increased (p < 0.05) compared with saline controls, and the ratio of pancreatic insulin to glucagon in liraglutide mice was similar to lean mice. Although liraglutide did not alter islet number or area, the proportion of beta cells per islet was significantly increased (p < 0.05) and alpha cells decreased (p < 0.05), with normalization of islet architecture. In harmony with this, cell proliferation was significantly (p < 0.001) augmented and apoptosis reduced (p < 0.001) in liraglutide treated mice. Expression of pancreatic islet glucose-dependent insulinotropic polypeptide immunoreactivity was observed in lean control and, particularly, liraglutide treated db/db mice, whereas control db/db mice exhibited little glucose-dependent insulinotropic polypeptide staining. CONCLUSION These data reveal that stable GLP-1 analogues exert important beneficial effects on pancreatic islet architecture and beta-cell turnover, indicating that they may be useful in the treatment of severe forms of diabetes with islet degeneration.
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Moffett RC, Vasu S, Flatt PR. Functional GIP receptors play a major role in islet compensatory response to high fat feeding in mice. Biochim Biophys Acta Gen Subj 2015; 1850:1206-14. [PMID: 25688757 DOI: 10.1016/j.bbagen.2015.02.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 01/30/2015] [Accepted: 02/09/2015] [Indexed: 02/06/2023]
Abstract
BACKGROUND Consumption of high fat diet and insulin resistance induce significant changes in pancreatic islet morphology and function essential for maintenance of normal glucose homeostasis. We have used incretin receptor null mice to evaluate the role of gastric inhibitory polypeptide (GIP) in this adaptive response. METHODS C57BL/6 and GIPRKO mice were fed high fat diet for 45 weeks from weaning. Changes of pancreatic islet morphology were assessed by immunohistochemistry. Body fat, glucose, insulin, glucagon, glucagon-like peptide 1 (GLP-1) and GIP were assessed by routine assays. RESULTS Compared with normal diet controls, high fat fed C57BL/6 mice exhibited increased body fat, hyperinsulinaemia and insulin resistance, associated with decreased pancreatic glucagon, unchanged pancreatic GLP-1 and marked increases of insulin, islet number, islet size and both beta- and alpha-cell areas. Beta cell proliferation and apoptosis were increased under high fat feeding, but the overall effect favoured enhanced beta cell mass. A broadly similar pattern of change was observed in high fat fed GIPRKO mice but islet compensation was severely impaired in every respect. The inability to enhance beta cell proliferation was associated with the depletion of pancreatic GLP-1 and lack of hyperinsulinaemic response, resulting in non-fasting hyperglycaemia. GIP and GLP-1 were expressed in islets of all groups of mice but high fat fed GIPRKO mice displayed decreased numbers of GLP-1 containing alpha cells plus non-functional enhancement of pancreatic GIP content. GENERAL SIGNIFICANCE These data suggest that GIP released from islet alpha-cells and intestinal K-cells plays an important role in islet adaptations to high fat feeding.
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Affiliation(s)
- R Charlotte Moffett
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK.
| | - Srividya Vasu
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK
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Vasu S, Moffett RC, McClenaghan NH, Flatt PR. Responses of GLP1-secreting L-cells to cytotoxicity resemble pancreatic β-cells but not α-cells. J Mol Endocrinol 2015; 54:91-104. [PMID: 25527608 DOI: 10.1530/jme-14-0214] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Little is known about responses of intestinal L-cells to chemical or cytokine-mediated attack and how these compare with pancreatic β- or α-cells. Administration of streptozotocin to mice induced severe diabetes, islet lymphocytic infiltration, increased α-cell proliferation and decreased numbers of β- and L-cells. In vitro, streptozotocin and cytokines reduced cell viability with higher lethal dose 50 values for α-TC1 cells. mRNA expression of Glut2 was lower and Cat was greater in GLUTag and α-TC1 cells compared with MIN6 cells. Cytotoxins affected the transcription of genes involved in secretion in GLUTag and MIN6 cells. They are also involved in upregulation of antioxidant defence enzymes, transcription of NfκB and Nos2, and production of nitrite in all cell types. Cytotoxin-induced DNA damage and apoptosis were apparent in all cells, but α-TC1 cells were less severely affected. Thus, responses of GLP1-secreting L-cells to cytotoxicity resemble β-cells, whereas α-cells are resistant due to differences in the expression of genes involved in cytotoxicity or antioxidant defence.
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Affiliation(s)
- Srividya Vasu
- SAAD Centre for Pharmacy and DiabetesUniversity of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK
| | - R Charlotte Moffett
- SAAD Centre for Pharmacy and DiabetesUniversity of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK
| | - Neville H McClenaghan
- SAAD Centre for Pharmacy and DiabetesUniversity of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK
| | - Peter R Flatt
- SAAD Centre for Pharmacy and DiabetesUniversity of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK
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