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Yang M, Fukui H, Eda H, Xu X, Kitayama Y, Hara K, Kodani M, Tomita T, Oshima T, Watari J, Miwa H. Involvement of gut microbiota in association between GLP-1/GLP-1 receptor expression and gastrointestinal motility. Am J Physiol Gastrointest Liver Physiol 2017; 312:G367-G373. [PMID: 28154011 DOI: 10.1152/ajpgi.00232.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 01/24/2017] [Accepted: 01/24/2017] [Indexed: 01/31/2023]
Abstract
The microbiota in the gut is known to play a pivotal role in host physiology by interacting with the immune and neuroendocrine systems in gastrointestinal (GI) tissues. Glucagon-like peptide 1 (GLP-1), a gut hormone, is involved in metabolism as well as GI motility. We examined how gut microbiota affects the link between GLP-1/GLP-1 receptor (GLP-1R) expression and motility of the GI tract. Germ-free (GF) mice (6 wk old) were orally administered a fecal bacterial suspension prepared from specific pathogen-free (SPF) mice, and then after fecal transplantation (FT) GI tissues were obtained from the GF mice at various time points. The expression of GLP-1 and its receptor was examined by immunohistochemistry, and gastrointestinal transit time (GITT) was measured by administration of carmine red solution. GLP-1 was expressed in endocrine cells in the colonic mucosa, and GLP-1R was expressed in myenteric neural cells throughout the GI wall. GLP-1R-positive cells throughout the GI wall were significantly fewer in GF mice with FT than in GF mice without gut microbiota reconstitution. GITT was significantly shorter in GF mice with FT than in control GF mice without FT and correlated with the number of GLP-1R-positive cells throughout the GI wall. GITT was significantly longer in GF control mice than in SPF mice. When those mice were treated with GLP-1 agonist extendin4, GITT was significantly longer in the GF mice. The gut microbiota may accelerate or at least modify GI motility while suppressing GLP-1R expression in myenteric neural cells throughout the GI tract.NEW & NOTEWORTHY The gut microbiota has been intensively studied, because it plays a pivotal role in various aspects of host physiology. On the other hand, glucagon-like peptide 1 (GLP-1) plays important roles in metabolism as well as gastrointestinal motility. In the present study, we have suggested that the gut microbiota accelerates gastrointestinal motility while suppressing the expression of GLP-1 receptor in myenteric neural cells throughout the gastrointestinal tract. We believe that this article is very timely and suggestive work.
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Affiliation(s)
- Mo Yang
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and.,Department of Digestive Diseases, Tianjin Medical University General Hospital, Tianjin, People's Republic of China
| | - Hirokazu Fukui
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
| | - Hirotsugu Eda
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
| | - Xin Xu
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and.,Department of Digestive Diseases, Tianjin Medical University General Hospital, Tianjin, People's Republic of China
| | - Yoshitaka Kitayama
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
| | - Ken Hara
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
| | - Mio Kodani
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
| | - Toshihiko Tomita
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
| | - Tadayuki Oshima
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
| | - Jiro Watari
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
| | - Hiroto Miwa
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan; and
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Chen J, Wang D, Wang F, Shi S, Chen Y, Yang B, Tang Y, Huang C. Exendin-4 inhibits structural remodeling and improves Ca 2+ homeostasis in rats with heart failure via the GLP-1 receptor through the eNOS/cGMP/PKG pathway. Peptides 2017; 90:69-77. [PMID: 28242257 DOI: 10.1016/j.peptides.2017.02.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 02/14/2017] [Accepted: 02/21/2017] [Indexed: 12/21/2022]
Abstract
The glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 is a long-acting analog of GLP-1, which stimulates insulin secretion and is clinically used in the treatment of type 2 diabetes. Previous studies have demonstrated that GLP-1 agonists and analogs serve as cardioprotective factors in various conditions. Disturbances in calcium cycling are characteristic of heart failure (HF); therefore, the aim of this study was to investigate the effect of exendin-4 (a GLP-1 mimetic) on the regulation of calcium handling and to identify the underlying mechanisms in an HF rat model after myocardial infarction (MI). Rats underwent surgical ligation of the left anterior descending coronary artery or sham surgery prior to infusion with vehicle, exendin-4, or exendin-4 and exendin9-39 for 4 weeks. Exendin-4 treatment decreased MI size, suppressed chamber dilation, myocyte hypertrophy, and fibrosis and improved in vivo heart function in the rats subjected to MI. Exendin-4 resulted in an increase in circulating GLP-1 and GLP-1R in ventricular tissues. Additionally, exendin-4 activated the eNOS/cGMP/PKG signaling pathway and inhibited the Ca2+/calmodulin-dependent kinase II (CaMKII) pathways. Myocytes isolated from exendin-4-treated hearts displayed higher Ca2+ transients, higher sarcoplasmic reticulum Ca2+ content, and higher l-type Ca2+ current densities than MI hearts. Exendin-4 treatment restored the protein expression of sarcoplasmic reticulum Ca2+ uptake ATPase (SERCA2a), phosphorylated phospholamban (PLB) and Cav1.2 and decreased the levels of phosphorylated ryanodine receptor (RyR). Moreover, the favorable effects of exendin-4 were significantly inhibited by exendin9-39 (a GLP-1 receptor antagonist). Exendin-4 treatment of an HF rat model after MI inhibited cardiac and cardiomyocytes progressive remodeling. In addition, Ca2+ handling and its molecular modulation were also improved by exendin-4 treatment. The beneficial effects of exendin-4 on cardiac remodeling may be mediated through activation of the eNOS/cGMP/PKG pathway.
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Affiliation(s)
- Jingjing Chen
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan University, Wuhan 430060, China
| | - Dandan Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan University, Wuhan 430060, China
| | - Fangai Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan University, Wuhan 430060, China
| | - Shaobo Shi
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan University, Wuhan 430060, China
| | - Yuting Chen
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan University, Wuhan 430060, China
| | - Bo Yang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan University, Wuhan 430060, China
| | - Yanhong Tang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan University, Wuhan 430060, China
| | - Congxin Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan University, Wuhan 430060, China.
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253
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Gaykema RP, Newmyer BA, Ottolini M, Raje V, Warthen DM, Lambeth PS, Niccum M, Yao T, Huang Y, Schulman IG, Harris TE, Patel MK, Williams KW, Scott MM. Activation of murine pre-proglucagon-producing neurons reduces food intake and body weight. J Clin Invest 2017; 127:1031-1045. [PMID: 28218622 DOI: 10.1172/jci81335] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 12/30/2016] [Indexed: 12/14/2022] Open
Abstract
Peptides derived from pre-proglucagon (GCG peptides) act in both the periphery and the CNS to change food intake, glucose homeostasis, and metabolic rate while playing a role in anxiety behaviors and physiological responses to stress. Although the actions of GCG peptides produced in the gut and pancreas are well described, the role of glutamatergic GGC peptide-secreting hindbrain neurons in regulating metabolic homeostasis has not been investigated. Here, we have shown that chemogenetic stimulation of GCG-producing neurons reduces metabolic rate and food intake in fed and fasted states and suppresses glucose production without an effect on glucose uptake. Stimulation of GCG neurons had no effect on corticosterone secretion, body weight, or conditioned taste aversion. In the diet-induced obese state, the effects of GCG neuronal stimulation on gluconeogenesis were lost, while the food intake-lowering effects remained, resulting in reductions in body weight and adiposity. Our work suggests that GCG peptide-expressing neurons can alter feeding, metabolic rate, and glucose production independent of their effects on hypothalamic pituitary-adrenal (HPA) axis activation, aversive conditioning, or insulin secretion. We conclude that GCG neurons likely stimulate separate populations of downstream cells to produce a change in food intake and glucose homeostasis and that these effects depend on the metabolic state of the animal.
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254
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Muscogiuri G, DeFronzo RA, Gastaldelli A, Holst JJ. Glucagon-like Peptide-1 and the Central/Peripheral Nervous System: Crosstalk in Diabetes. Trends Endocrinol Metab 2017; 28:88-103. [PMID: 27871675 DOI: 10.1016/j.tem.2016.10.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 09/30/2016] [Accepted: 10/03/2016] [Indexed: 12/17/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) is released in response to meals and exerts important roles in the maintenance of normal glucose homeostasis. GLP-1 is also important in the regulation of neurologic and cognitive functions. These actions are mediated via neurons in the nucleus of the solitary tract that project to multiple regions expressing GLP-1 receptors (GLP-1Rs). Treatment with GLP-1R agonists (GLP-1-RAs) reduces ischemia-induced hyperactivity, oxidative stress, neuronal damage and apoptosis, cerebral infarct volume, and neurologic damage, after cerebral ischemia, in experimental models. Ongoing human trials report a neuroprotective effect of GLP-1-RAs in Alzheimer's and Parkinson's disease. In this review, we discuss the role of GLP-1 and GLP-1-RAs in the nervous system with focus on GLP-1 actions on appetite regulation, glucose homeostasis, and neuroprotection.
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Affiliation(s)
| | - Ralph A DeFronzo
- Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA
| | - Amalia Gastaldelli
- Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA; Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy.
| | - Jens J Holst
- NNF Center for Basic Metabolic Research and Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark
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255
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Synergistic effects of metformin with liraglutide against endothelial dysfunction through GLP-1 receptor and PKA signalling pathway. Sci Rep 2017; 7:41085. [PMID: 28145471 PMCID: PMC5286534 DOI: 10.1038/srep41085] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 12/15/2016] [Indexed: 01/19/2023] Open
Abstract
Metformin or glucagon-like peptide-1 (GLP-1) analogue liraglutide has cardiovascular benefits. However, it is not clear whether their combined treatment have additive or synergistic effects on the vasculature. In this study, human umbilical vein endothelial cells (HUVECs), exposed to palmitic acid (PA) to induce endothelial dysfunction, were incubated with metformin, liraglutide or their combination. High fat diet (HFD)-fed ApoE−/− mice were randomized into control, metformin, liraglutide, and combination treatment groups. Results showed that in PA-treated HUVECs and HFD-fed ApoE−/− mice, combination of metformin and liraglutide at lower dose significantly improved endothelial dysfunction compared with the single treatment. Metformin upregulated GLP-1 receptor (GLP-1R) level and protein kinase A (PKA) phosphorylation. However, PKA inhibition but not GLP-1R blockade eliminated the protective effects of metformin on endothelial function. Furthermore, AMPK inhibitor compound C abolished the metformin-mediated upregulation of GLP-1R level and PKA phosphorylation. In conclusion, combination of metformin and liraglutide has synergistic protective effects on endothelial function. Moreover, metformin stimulates GLP-1R and PKA signalling via AMPK-dependent pathway, which may account for its synergistic protective effects with liraglutide. Our findings provide new insights on the interaction between metformin and GLP-1, and provide important information for designing new GLP-1-based therapy strategies in treating type 2 diabetes.
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256
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Li J, Zheng J, Wang S, Lau HK, Fathi A, Wang Q. Cardiovascular Benefits of Native GLP-1 and its Metabolites: An Indicator for GLP-1-Therapy Strategies. Front Physiol 2017; 8:15. [PMID: 28194113 PMCID: PMC5276855 DOI: 10.3389/fphys.2017.00015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 01/09/2017] [Indexed: 12/23/2022] Open
Abstract
Cardiovascular disease is a common co-morbidity and leading cause of death in patients with type 2 diabetes mellitus (T2DM). Glucagon-like peptide 1 (GLP-1) is a peptide hormone produced by intestinal L cells in response to feeding. Native GLP-1 (7-36) amide is rapidly degraded by diaminopeptidyl peptidase-4 (DPP4) to GLP-1 (9-36) amide, making 9-36a the major circulating form. While it is 7-36a, and not its metabolites, which exerts trophic effects on islet β-cells, recent studies suggest that both 7-36a and its metabolites have direct cardiovascular effects, including preserving cardiomyocyte viability, ameliorating cardiac function, and vasodilation. In particular, the difference in cardiovascular effects between 7-36a and 9-36a is attracting attention. Growing evidence has strengthened the presumption that their cardiovascular effects are overlapping, but distinct and complementary to each other; 7-36a exerts cardiovascular effects in a GLP-1 receptor (GLP-1R) dependent pathway, whereas 9-36a does so in a GLP-1R independent pathway. GLP-1 therapies have been developed using two main strategies: DPP4-resistant GLP-1 analogs/GLP-1R agonists and DPP4 inhibitors, which both aim to prolong the life-time of circulating 7-36a. One prominent concern that should be addressed is that the cardiovascular benefits of 9-36a are lacking in these strategies. This review attempts to differentiate the cardiovascular effects between 7-36a and 9-36a in order to provide new insights into GLP-1 physiology, and facilitate our efforts to develop a superior GLP-1-therapy strategy for T2DM and cardiovascular diseases.
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Affiliation(s)
- Junfeng Li
- Department of Endocrinology and Metabolism, Huashan Hospital, Shanghai Medical College, Fudan UniversityShanghai, China; Department of Endocrinology, Renmin Hospital of Wuhan UniversityWuhan, China
| | - Juan Zheng
- Division of Endocrinology and Metabolism, the Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's HospitalToronto, ON, Canada; Department of Physiology, Faculty of Medicine, University of TorontoToronto, ON, Canada
| | - Susanne Wang
- Division of Endocrinology and Metabolism, the Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's HospitalToronto, ON, Canada; Department of Physiology, Faculty of Medicine, University of TorontoToronto, ON, Canada
| | - Harry K Lau
- Division of Endocrinology and Metabolism, the Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's HospitalToronto, ON, Canada; Department of Physiology, Faculty of Medicine, University of TorontoToronto, ON, Canada
| | - Ali Fathi
- Division of Endocrinology and Metabolism, the Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital Toronto, ON, Canada
| | - Qinghua Wang
- Department of Endocrinology and Metabolism, Huashan Hospital, Shanghai Medical College, Fudan UniversityShanghai, China; Division of Endocrinology and Metabolism, the Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's HospitalToronto, ON, Canada; Department of Physiology, Faculty of Medicine, University of TorontoToronto, ON, Canada
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257
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de la Monte SM. Insulin Resistance and Neurodegeneration: Progress Towards the Development of New Therapeutics for Alzheimer's Disease. Drugs 2017; 77:47-65. [PMID: 27988872 PMCID: PMC5575843 DOI: 10.1007/s40265-016-0674-0] [Citation(s) in RCA: 196] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Alzheimer's disease (AD) should be regarded as a degenerative metabolic disease caused by brain insulin resistance and deficiency, and overlapping with the molecular, biochemical, pathophysiological, and metabolic dysfunctions in diabetes mellitus, non-alcoholic fatty liver disease, and metabolic syndrome. Although most of the diagnostic and therapeutic approaches over the past several decades have focused on amyloid-beta (Aβ42) and aberrantly phosphorylated tau, which could be caused by consequences of brain insulin resistance, the broader array of pathologies including white matter atrophy with loss of myelinated fibrils and leukoaraiosis, non-Aβ42 microvascular disease, dysregulated lipid metabolism, mitochondrial dysfunction, astrocytic gliosis, neuro-inflammation, and loss of synapses vis-à-vis growth of dystrophic neurites, is not readily accounted for by Aβ42 accumulations, but could be explained by dysregulated insulin/IGF-1 signaling with attendant impairments in signal transduction and gene expression. This review covers the diverse range of brain abnormalities in AD and discusses how insulins, incretins, and insulin sensitizers could be utilized to treat at different stages of neurodegeneration.
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Affiliation(s)
- Suzanne M de la Monte
- Department of Neurology, Rhode Island Hospital, and the Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 419, Providence, RI, 02903, USA.
- Department of Neurosurgery, Rhode Island Hospital, and the Alpert Medical School of Brown University, Providence, RI, USA.
- Department of Neuropathology, Rhode Island Hospital, and the Alpert Medical School of Brown University, Providence, RI, USA.
- Department of Pathology, Rhode Island Hospital, and the Alpert Medical School of Brown University, Providence, RI, USA.
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258
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Pujadas G, Drucker DJ. Vascular Biology of Glucagon Receptor Superfamily Peptides: Mechanistic and Clinical Relevance. Endocr Rev 2016; 37:554-583. [PMID: 27732058 DOI: 10.1210/er.2016-1078] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Regulatory peptides produced in islet and gut endocrine cells, including glucagon, glucagon-like peptide-1 (GLP-1), GLP-2, and glucose-dependent insulinotropic polypeptide, exert actions with considerable metabolic importance and translational relevance. Although the clinical development of GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors has fostered research into how these hormones act on the normal and diseased heart, less is known about the actions of these peptides on blood vessels. Here we review the effects of these peptide hormones on normal blood vessels and highlight their vascular actions in the setting of experimental and clinical vascular injury. The cellular localization and signal transduction properties of the receptors for glucagon, GLP-1, GLP-2, and glucose-dependent insulinotropic polypeptide are discussed, with emphasis on endothelial cells and vascular smooth muscle cells. The actions of these peptides on the control of blood flow, blood pressure, angiogenesis, atherosclerosis, and vascular inflammation are reviewed with a focus on elucidating direct and indirect mechanisms of action. How these peptides traverse the blood-brain barrier is highlighted, with relevance to the use of GLP-1 receptor agonists to treat obesity and neurodegenerative disorders. Wherever possible, we compare actions identified in cell lines and primary cell culture with data from preclinical studies and, when available, results of human investigation, including studies in subjects with diabetes, obesity, and cardiovascular disease. Throughout the review, we discuss pitfalls, limitations, and challenges of the existing literature and highlight areas of controversy and uncertainty. The increasing use of peptide-based therapies for the treatment of diabetes and obesity underscores the importance of understanding the vascular biology of peptide hormone action.
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Affiliation(s)
- Gemma Pujadas
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada
| | - Daniel J Drucker
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada
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259
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Lutz TA. Gut hormones such as amylin and GLP-1 in the control of eating and energy expenditure. INTERNATIONAL JOURNAL OF OBESITY SUPPLEMENTS 2016; 6:S15-S21. [PMID: 28685025 DOI: 10.1038/ijosup.2016.4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The control of meal size is the best studied aspect of the control of energy balance, and manipulation of this system constitutes a promising target to treat obesity. A major part of this control system is based on gastrointestinal hormones such as glucagon-like peptide-1 (GLP-1) or amylin, which are released in response to a meal and which limit the size of an ongoing meal. Both amylin and GLP-1 have also been shown to increase energy expenditure in experimental rodents, but mechanistically we know much less how this effect may be mediated, which brain sites may be involved, and what the physiological relevance of these findings may be. Most studies indicate that the effect of peripheral amylin is centrally mediated via the area postrema, but other brain areas, such as the ventral tegmental area, may also be involved. GLP-1's effect on eating seems to be mainly mediated by vagal afferents projecting to the caudal hindbrain. Chronic exposure to amylin, GLP-1 or their analogs decrease food intake and body weight gain. Next to the induction of satiation, amylin may also constitute an adiposity signal and in fact interact with the adiposity signal leptin. Amylin analogs are under clinical consideration for their effect to reduce food intake and body weight in humans, and similar to rodents, amylin analogs seem to be particularly active when combined with leptin analogs.
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Affiliation(s)
- T A Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich, Zurich, Switzerland.,Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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260
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O'Malley D. Neuroimmune Cross Talk in the Gut. Neuroendocrine and neuroimmune pathways contribute to the pathophysiology of irritable bowel syndrome. Am J Physiol Gastrointest Liver Physiol 2016; 311:G934-G941. [PMID: 27742703 PMCID: PMC5130550 DOI: 10.1152/ajpgi.00272.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/29/2016] [Indexed: 02/06/2023]
Abstract
Irritable bowel syndrome (IBS) is a common disorder characterized by recurrent abdominal pain, bloating, and disturbed bowel habit, symptoms that impact the quality of life of sufferers. The pathophysiological changes underlying this multifactorial condition are complex and include increased sensitivity to luminal and mucosal factors, resulting in altered colonic transit and visceral pain. Moreover, dysfunctional communication in the bidirectional signaling axis between the brain and the gut, which involves efferent and afferent branches of the peripheral nervous system, circulating endocrine hormones, and local paracrine and neurocrine factors, including immune and perhaps even microbial signaling molecules, has a role to play in this disorder. This minireview will examine recent advances in our understanding of the pathophysiology of IBS and assess how cross talk between hormones, immune, and microbe-derived factors and their neuromodulatory effects on peripheral nerves may underlie IBS symptomatology.
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Affiliation(s)
- Dervla O'Malley
- Department of Physiology, University College Cork, Cork, Ireland; and .,APC Microbiome Institute, University College Cork, Cork, Ireland
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261
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Farkas I, Vastagh C, Farkas E, Bálint F, Skrapits K, Hrabovszky E, Fekete C, Liposits Z. Glucagon-Like Peptide-1 Excites Firing and Increases GABAergic Miniature Postsynaptic Currents (mPSCs) in Gonadotropin-Releasing Hormone (GnRH) Neurons of the Male Mice via Activation of Nitric Oxide (NO) and Suppression of Endocannabinoid Signaling Pathways. Front Cell Neurosci 2016; 10:214. [PMID: 27672360 PMCID: PMC5018486 DOI: 10.3389/fncel.2016.00214] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 08/26/2016] [Indexed: 12/25/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1), a metabolic signal molecule, regulates reproduction, although, the involved molecular mechanisms have not been elucidated, yet. Therefore, responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the GLP-1 analog Exendin-4 and elucidation of molecular pathways acting downstream to the GLP-1 receptor (GLP-1R) have been challenged. Loose patch-clamp recordings revealed that Exendin-4 (100 nM-5 μM) elevated firing rate in hypothalamic GnRH-GFP neurons of male mice via activation of GLP-1R. Whole-cell patch-clamp measurements demonstrated increased excitatory GABAergic miniature postsynaptic currents (mPSCs) frequency after Exendin-4 administration, which was eliminated by the GLP-1R antagonist Exendin-3(9-39) (1 μM). Intracellular application of the G-protein inhibitor GDP-β-S (2 mM) impeded action of Exendin-4 on mPSCs, suggesting direct excitatory action of GLP-1 on GnRH neurons. Blockade of nitric-oxide (NO) synthesis by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME; 100 μM) or N(5)-[Imino(propylamino)methyl]-L-ornithine hydrochloride (NPLA; 1 μM) or intracellular scavenging of NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO; 1 mM) partially attenuated the excitatory effect of Exendin-4. Similar partial inhibition was achieved by hindering endocannabinoid pathway using cannabinoid receptor type-1 (CB1) inverse-agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-(1-piperidyl) pyrazole-3-carboxamide (AM251; 1 μM). Simultaneous blockade of NO and endocannabinoid signaling mechanisms eliminated action of Exendin-4 suggesting involvement of both retrograde machineries. Intracellular application of the transient receptor potential vanilloid 1 (TRPV1)-antagonist 2E-N-(2, 3-Dihydro-1,4-benzodioxin-6-yl)-3-[4-(1, 1-dimethylethyl)phenyl]-2-Propenamide (AMG9810; 10 μM) or the fatty acid amide hydrolase (FAAH)-inhibitor PF3845 (5 μM) impeded the GLP-1-triggered endocannabinoid pathway indicating an anandamide-TRPV1-sensitive control of 2-arachidonoylglycerol (2-AG) production. Furthermore, GLP-1 immunoreactive (IR) axons innervated GnRH neurons in the hypothalamus suggesting that GLP-1 of both peripheral and neuronal sources can modulate GnRH neurons. RT-qPCR study confirmed the expression of GLP-1R and neuronal NO synthase (nNOS) mRNAs in GnRH-GFP neurons. Immuno-electron microscopic analysis revealed the presence of nNOS protein in GnRH neurons. These results indicate that GLP-1 exerts direct facilitatory actions via GLP-1R on GnRH neurons and modulates NO and 2-AG retrograde signaling mechanisms that control the presynaptic excitatory GABAergic inputs to GnRH neurons.
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Affiliation(s)
- Imre Farkas
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Erzsébet Farkas
- Laboratory of Integrative Neuroendocrinology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary; Roska Tamás Doctoral School of Sciences and Technology, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary
| | - Flóra Bálint
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary; Roska Tamás Doctoral School of Sciences and Technology, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary
| | - Katalin Skrapits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Csaba Fekete
- Laboratory of Integrative Neuroendocrinology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary; Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tupper Research Institute, Tufts Medical CenterBoston, MA, USA
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary; Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary
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262
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Cox HM. Neuroendocrine peptide mechanisms controlling intestinal epithelial function. Curr Opin Pharmacol 2016; 31:50-56. [PMID: 27597736 DOI: 10.1016/j.coph.2016.08.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 07/20/2016] [Accepted: 08/12/2016] [Indexed: 01/01/2023]
Abstract
Enteroendocrine cells (EECs) contain different combinations of hormones, which are released following stimulation of nutrient receptors that are selectively expressed by these cells. This chemosensation varies according to the intestinal area and species of interest, and responses to meals are rapidly modified following bariatric surgery. Such surgically-induced gastrointestinal (GI) changes highlight considerable enteroplasticity, however our understanding of even the acute physiological control and consequences of neuroendocrine peptide release is still under-developed. This review focuses on recent advances in nutrient G protein-coupled receptor (GPCR)-chemosensation in L cells, the patterns of peptide release and consequent changes in GI function. A clearer resolution of these mucosal mechanisms will shed light on potential receptor-target combinations that could provide less-invasive anti-diabesity strategies in future.
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Affiliation(s)
- Helen M Cox
- Wolfson Centre for Age-Related Diseases, IoPPN, King's College London, London SE1 1UL, UK.
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263
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264
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Bauer PV, Duca FA. Targeting the gastrointestinal tract to treat type 2 diabetes. J Endocrinol 2016; 230:R95-R113. [PMID: 27496374 DOI: 10.1530/joe-16-0056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 06/20/2016] [Indexed: 12/12/2022]
Abstract
The rising global rates of type 2 diabetes and obesity present a significant economic and social burden, underscoring the importance for effective and safe therapeutic options. The success of glucagon-like-peptide-1 receptor agonists in the treatment of type 2 diabetes, along with the potent glucose-lowering effects of bariatric surgery, highlight the gastrointestinal tract as a potential target for diabetes treatment. Furthermore, recent evidence suggests that the gut plays a prominent role in the ability of metformin to lower glucose levels. As such, the current review highlights some of the current and potential pathways in the gut that could be targeted to improve glucose homeostasis, such as changes in nutrient sensing, gut peptides, gut microbiota and bile acids. A better understanding of these pathways will lay the groundwork for novel gut-targeted antidiabetic therapies, some of which have already shown initial promise.
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Affiliation(s)
- Paige V Bauer
- Toronto General Hospital Research Institute and Department of MedicineUHN, Toronto, ON, Canada Department of PhysiologyUniversity of Toronto, Toronto, ON, Canada
| | - Frank A Duca
- Toronto General Hospital Research Institute and Department of MedicineUHN, Toronto, ON, Canada
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265
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Saisho Y. Pancreas Volume and Fat Deposition in Diabetes and Normal Physiology: Consideration of the Interplay Between Endocrine and Exocrine Pancreas. Rev Diabet Stud 2016; 13:132-147. [PMID: 28012279 DOI: 10.1900/rds.2016.13.132] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The pancreas is comprised of exocrine and endocrine components. Despite the fact that they are derived from a common origin in utero, these two compartments are often studied individually because of the different roles and functions of the exocrine and endocrine pancreas. Recent studies have shown that not only type 1 diabetes (T1D), but also type 2 diabetes (T2D), is characterized by a deficit in beta-cell mass, suggesting that pathological changes in the pancreas are critical events in the natural history of diabetes. In both patients with T1D and those with T2D, pancreas mass and exocrine function have been reported to be reduced. On the other hand, pancreas volume and pancreatic fat increase with obesity. Increased beta-cell mass with increasing obesity has also been observed in humans, and ectopic fat deposits in the pancreas have been reported to cause beta-cell dysfunction. Moreover, neogenesis and transdifferentiation from the exocrine to the endocrine compartment in the postnatal period are regarded as a source of newly formed beta-cells. These findings suggest that there is important interplay between the endocrine and exocrine pancreas throughout life. This review summarizes the current knowledge on physiological and pathological changes in the exocrine and endocrine pancreas (i.e., beta-cell mass), and discusses the potential mechanisms of the interplay between the two compartments in humans to understand the pathophysiology of diabetes better.
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Affiliation(s)
- Yoshifumi Saisho
- Department of Internal Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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266
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Abstract
Glucagon-like peptide-1, produced predominantly in enteroendocrine cells, controls glucose metabolism and energy homeostasis through regulation of islet hormone secretion, gastrointestinal motility, and food intake, enabling development of GLP-1 receptor (GLP-1R) agonists for the treatment of diabetes and obesity. GLP-1 also acts on the immune system to suppress inflammation, and GLP-1R signaling in multiple tissues impacts cardiovascular function in health and disease. Here we review how GLP-1 and clinically approved GLP-1R agonists engage mechanisms that influence the risk of developing cardiovascular disease. We discuss how GLP-1R agonists modify inflammation, cardiovascular physiology, and pathophysiology in normal and diabetic animals through direct and indirect mechanisms and review human studies illustrating mechanisms linking GLP-1R signaling to modification of the cardiovascular complications of diabetes. The risks and benefits of GLP-1R agonists are updated in light of recent data suggesting that GLP-1R agonists favorably modify outcomes in diabetic subjects at high risk for cardiovascular events.
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Affiliation(s)
- Daniel J Drucker
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada.
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267
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Liu J, Pang ZP. Glucagon-like peptide-1 drives energy metabolism on the synaptic highway. FEBS J 2016; 283:4413-4423. [DOI: 10.1111/febs.13785] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/04/2016] [Accepted: 06/16/2016] [Indexed: 01/17/2023]
Affiliation(s)
- Ji Liu
- Child Health Institute of New Jersey; Rutgers University Robert Wood Johnson Medical School; New Brunswick NJ USA
- Department of Neuroscience and Cell Biology; Rutgers University Robert Wood Johnson Medical School; New Brunswick NJ USA
| | - Zhiping P. Pang
- Child Health Institute of New Jersey; Rutgers University Robert Wood Johnson Medical School; New Brunswick NJ USA
- Department of Neuroscience and Cell Biology; Rutgers University Robert Wood Johnson Medical School; New Brunswick NJ USA
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268
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Veedfald S, Hansen M, Christensen LW, Larsen SAH, Hjøllund KR, Plamboeck A, Hartmann B, Deacon CF, Holst JJ. The insulinotropic effect of exogenous glucagon-like peptide-1 is not affected by acute vagotomy in anaesthetized pigs. Exp Physiol 2016; 101:895-912. [DOI: 10.1113/ep085692] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 03/21/2016] [Indexed: 12/24/2022]
Affiliation(s)
- Simon Veedfald
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Marie Hansen
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Louise Wulff Christensen
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Sara Agnete Hjort Larsen
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Karina Rahr Hjøllund
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Astrid Plamboeck
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Carolyn Fiona Deacon
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Jens Juul Holst
- Department of Biomedical Sciences (endocrinology section) and NNF Center for Basic Metabolic Research (translational metabolic physiology section), Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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269
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Holst JJ, Gribble F, Horowitz M, Rayner CK. Roles of the Gut in Glucose Homeostasis. Diabetes Care 2016; 39:884-92. [PMID: 27222546 DOI: 10.2337/dc16-0351] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 03/22/2016] [Indexed: 02/05/2023]
Abstract
The gastrointestinal tract plays a major role in the regulation of postprandial glucose profiles. Gastric emptying is a highly regulated process, which normally ensures a limited and fairly constant delivery of nutrients and glucose to the proximal gut. The subsequent digestion and absorption of nutrients are associated with the release of a set of hormones that feeds back to regulate subsequent gastric emptying and regulates the release of insulin, resulting in downregulation of hepatic glucose production and deposition of glucose in insulin-sensitive tissues. These remarkable mechanisms normally keep postprandial glucose excursions low, regardless of the load of glucose ingested. When the regulation of emptying is perturbed (e.g., pyloroplasty, gastric sleeve or gastric bypass operation), postprandial glycemia may reach high levels, sometimes followed by profound hypoglycemia. This article discusses the underlying mechanisms.
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Affiliation(s)
- Jens Juul Holst
- The Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Fiona Gribble
- Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, U.K
| | - Michael Horowitz
- Discipline of Medicine, University of Adelaide and Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Chris K Rayner
- Discipline of Medicine, University of Adelaide and Royal Adelaide Hospital, Adelaide, South Australia, Australia
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270
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Zhang Y, Zhou H, Wu W, Shi C, Hu S, Yin T, Ma Q, Han T, Zhang Y, Tian F, Chen Y. Liraglutide protects cardiac microvascular endothelial cells against hypoxia/reoxygenation injury through the suppression of the SR-Ca(2+)-XO-ROS axis via activation of the GLP-1R/PI3K/Akt/survivin pathways. Free Radic Biol Med 2016; 95:278-92. [PMID: 27038735 DOI: 10.1016/j.freeradbiomed.2016.03.035] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 03/04/2016] [Accepted: 03/29/2016] [Indexed: 01/15/2023]
Abstract
Microvascular endothelial cells (CMECs) oxidative damage resulting from hypoxia/reoxygenation (H/R) injury is responsible for microcirculation perfusion disturbances and the progression of cardiac dysfunction. However, few strategies are available to reverse such pathologies. Here, we studied the effects and mechanisms of liraglutide on CEMCs oxidative damage, focusing in particular on calcium overload-triggered free radical injury signals and the GLP-1R/PI3K/Akt/survivin survival pathways. The results indicate that H/R increased IP3R expression but reduced SERCA2a expression, which rapidly raised intracellular Ca(2+) levels, subsequently leading to Ca(2+)-dependent xanthine oxidase (XO) activation, reactive oxygen species (ROS) production and the cellular apoptosis of CMECs. However, liraglutide pretreatment abrogated Ca(2+)-mediated oxidative apoptosis. Furthermore, liraglutide regulated the rate of IP3R/SERCA2a gene transcription and conserved SERCA2a-ATPase activity via the maintenance of ATP production under H/R, which drove excessive Ca(2+) reflux to the sarcoplasmic reticulum (SR) and inhibited Ca(2+) release from the SR, ultimately restoring Ca(2+) homeostasis. Furthermore, the regulatory role of liraglutide on Ca(2+) balance in conjunction with its up-regulation of superoxide dismutase, glutathione and glutathione peroxidase collectively scavenged the excess ROS under H/R. Moreover, we showed that liraglutide strengthened Akt phosphorylation and subsequently survivin expression. In addition, both the blockade of the GLP-1R/PI3K/Akt pathways and the siRNA-mediated knockdown of survivin abolished the protective effects of liraglutide on SR-Ca(2+) function and CMECs oxidative apoptosis. In summary, this study confirmed that H/R induced CMECs oxidative damage through the SR-Ca(2+)-XO-ROS injury signals and that liraglutide pretreatment may suppress such CMECs damage through the PI3K/Akt/survivin pathways.
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Affiliation(s)
- Ying Zhang
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China
| | - Hao Zhou
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China
| | - Wenbo Wu
- Department of Burn surgery and Plastic surgery, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing, China
| | - Chen Shi
- Department of Radiotherapy, Beijing Cancer Hospital, Beijing, China
| | - Shunying Hu
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China
| | - Tong Yin
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China
| | - Qiang Ma
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China
| | - Tianwen Han
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China
| | - Yingqian Zhang
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China
| | - Feng Tian
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China
| | - Yundai Chen
- Department of Cardiology, Chinese PLA General Hospital, #28 Fuxing Road, Beijing 100853, China.
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271
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Cantini G, Mannucci E, Luconi M. Perspectives in GLP-1 Research: New Targets, New Receptors. Trends Endocrinol Metab 2016; 27:427-438. [PMID: 27091492 DOI: 10.1016/j.tem.2016.03.017] [Citation(s) in RCA: 55] [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: 02/21/2016] [Revised: 03/27/2016] [Accepted: 03/30/2016] [Indexed: 02/06/2023]
Abstract
The incretin hormone glucagon-like peptide-1 (GLP-1) binds to and activates its G-protein-coupled-receptor GLP-1R to reduce glycaemia through the stimulation of insulin and suppression of pancreatic glucagon secretion. Recently, GLP-1 effects unrelated to glucose homeostasis have been discovered in myocardium, bone, adipose tissue, and other target organs, which appear to be mainly mediated by GLP-1R-independent pathways. Here, we summarize knowledge on GLP-1R agonists (GLP-1RAs) as they relate to the improvement of glucose control, and focus on the most recently described effects, discussing the preclinical evidence of the involvement of alternative receptors and signalling mechanisms. It is now evident that the universe of GLP-1RAs is expanding further from the initial incretin effect, opening new unforeseen avenues for research and clinical applications.
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Affiliation(s)
- Giulia Cantini
- Department of Experimental and Clinical Biomedical Sciences, Endocrinology Unit, University of Florence, Florence, Italy.
| | - Edoardo Mannucci
- Department of Experimental and Clinical Biomedical Sciences, Endocrinology Unit, University of Florence, Florence, Italy; Diabetes Agency, Careggi Hospital, Florence, Italy
| | - Michaela Luconi
- Department of Experimental and Clinical Biomedical Sciences, Endocrinology Unit, University of Florence, Florence, Italy.
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272
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Greiner TU, Bäckhed F. Microbial regulation of GLP-1 and L-cell biology. Mol Metab 2016; 5:753-8. [PMID: 27617198 PMCID: PMC5004117 DOI: 10.1016/j.molmet.2016.05.012] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 05/17/2016] [Accepted: 05/20/2016] [Indexed: 12/21/2022] Open
Abstract
Background The gut microbiota is associated with several of metabolic diseases, including obesity and type 2 diabetes and affects host physiology through distinct mechanisms. The microbiota produces a vast array of metabolites that signal to host cells in the intestine as well as in more distal organs. Scope of review Enteroendocrine cells acts as ‘chemo sensors’ of the intestinal milieu by expressing a large number of receptors, which respond to different metabolites and nutrients, and signal to host by a wide variety of hormones. However, enteroendocrine cells differ along the length of the gut in terms of hormones expressed and receptor repertoire. Also, the microbial ecology and dietary substrates differ along the length of the gut, providing further evidence for unique functions of specific subpopulations among enteroendocrine cells. Here we will review how the gut microbiota interacts with L-cells in the small and large intestine and the resulting effects on the host. Major conclusions Microbial metabolites can be sensed differently by specific subpopulations of enteroendocrine cells. Furthermore, hormones such as GLP-1 can have different functions when originating from the small intestine or colon. This article is part of a special issue on microbiota.
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Affiliation(s)
- Thomas U Greiner
- Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Fredrik Bäckhed
- Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden; Novo Nordisk Foundation Center for Basic Metabolic Research, Section for Metabolic Receptology and Enteroendocrinology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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273
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Kankanala SR, Syed R, Gong Q, Ren B, Rao X, Zhong J. Cardiovascular safety of dipeptidyl peptidase-4 inhibitors: recent evidence on heart failure. Am J Transl Res 2016; 8:2450-2458. [PMID: 27347354 PMCID: PMC4891459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 04/17/2016] [Indexed: 06/06/2023]
Abstract
The cardiovascular safety of DPP4 inhibitors as a class, especially in regards to heart failure, has been questioned after the publication of first trials (SAVOR-TIMI 53 and EXAMINE) assessing the cardiovascular risks of DPP4 inhibitors alogliptin and sitagliptin in 2013. Although there were no increased risks in composite cardiovascular outcomes, the SAVOR-TIMI 53 trial reported a 27% increase in hospitalization for heart failure in diabetic patients who received the DPP4 inhibitor saxagliptin. There has been substantial increase in knowledge on the heart failure effect of DPP4 inhibition since 2013. This review will summarize the role of the DPP4/incretin axis in heart failure and discuss the findings from recent large scale clinical trials assessing the effects of DPP4 inhibitors on heart failure.
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Affiliation(s)
- Saumya Reddy Kankanala
- Division of Cardiovascular Medicine, University of Maryland School of MedicineBaltimore, MD 21201, USA
| | - Rafay Syed
- Division of Cardiovascular Medicine, University of Maryland School of MedicineBaltimore, MD 21201, USA
| | - Quan Gong
- Department of Immunology, School of Medicine, Yangtze UniversityJingzhou, Hubei 434023, China
| | - Boxu Ren
- Department of Immunology, School of Medicine, Yangtze UniversityJingzhou, Hubei 434023, China
| | - Xiaoquan Rao
- Division of Cardiovascular Medicine, University of Maryland School of MedicineBaltimore, MD 21201, USA
| | - Jixin Zhong
- Division of Cardiovascular Medicine, University of Maryland School of MedicineBaltimore, MD 21201, USA
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274
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Fournel A, Marlin A, Abot A, Pasquio C, Cirillo C, Cani PD, Knauf C. Glucosensing in the gastrointestinal tract: Impact on glucose metabolism. Am J Physiol Gastrointest Liver Physiol 2016; 310:G645-58. [PMID: 26939867 PMCID: PMC4867329 DOI: 10.1152/ajpgi.00015.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 02/25/2016] [Indexed: 01/31/2023]
Abstract
The gastrointestinal tract is an important interface of exchange between ingested food and the body. Glucose is one of the major dietary sources of energy. All along the gastrointestinal tube, e.g., the oral cavity, small intestine, pancreas, and portal vein, specialized cells referred to as glucosensors detect variations in glucose levels. In response to this glucose detection, these cells send hormonal and neuronal messages to tissues involved in glucose metabolism to regulate glycemia. The gastrointestinal tract continuously communicates with the brain, especially with the hypothalamus, via the gut-brain axis. It is now well established that the cross talk between the gut and the brain is of crucial importance in the control of glucose homeostasis. In addition to receiving glucosensing information from the gut, the hypothalamus may also directly sense glucose. Indeed, the hypothalamus contains glucose-sensitive cells that regulate glucose homeostasis by sending signals to peripheral tissues via the autonomous nervous system. This review summarizes the mechanisms by which glucosensors along the gastrointestinal tract detect glucose, as well as the results of such detection in the whole body, including the hypothalamus. We also highlight how disturbances in the glucosensing process may lead to metabolic disorders such as type 2 diabetes. A better understanding of the pathways regulating glucose homeostasis will further facilitate the development of novel therapeutic strategies for the treatment of metabolic diseases.
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Affiliation(s)
- Audren Fournel
- 1NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
| | - Alysson Marlin
- 1NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
| | - Anne Abot
- 1NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
| | - Charles Pasquio
- 1NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
| | - Carla Cirillo
- 2Laboratory for Enteric NeuroScience (LENS), University of Leuven, Leuven, Belgium; and
| | - Patrice D. Cani
- 3NeuroMicrobiota, European Associated Laboratory, Université Catholique de Louvain (UCL), Louvain Drug Research Institute (LDRI), Metabolism and Nutrition Research Group, WELBIO (Walloon Excellence in Life sciences and BIOtechnology), Brussels, Belgium
| | - Claude Knauf
- NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
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275
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Tudurí E, López M, Diéguez C, Nadal A, Nogueiras R. Glucagon-Like Peptide 1 Analogs and their Effects on Pancreatic Islets. Trends Endocrinol Metab 2016; 27:304-318. [PMID: 27062006 DOI: 10.1016/j.tem.2016.03.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 03/04/2016] [Accepted: 03/04/2016] [Indexed: 02/07/2023]
Abstract
Glucagon-like peptide 1 (GLP-1) exerts many actions that improve glycemic control. GLP-1 stimulates glucose-stimulated insulin secretion and protects β cells, while its extrapancreatic effects include cardioprotection, reduction of hepatic glucose production, and regulation of satiety. Although an appealing antidiabetic drug candidate, the rapid degradation of GLP-1 by dipeptidyl peptidase 4 (DPP-4) means that its therapeutic use is unfeasible, and this prompted the development of two main GLP-1 therapies: long-acting GLP-1 analogs and DPP-4 inhibitors. In this review, we focus on the pancreatic effects exerted by current GLP-1 derivatives used to treat diabetes. Based on the results from in vitro and in vivo studies in humans and animal models, we describe the specific actions of GLP-1 analogs on the synthesis, processing, and secretion of insulin, islet morphology, and β cell proliferation and apoptosis.
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Affiliation(s)
- Eva Tudurí
- Instituto de Investigaciones Sanitarias (IDIS), CIMUS, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain.
| | - Miguel López
- Instituto de Investigaciones Sanitarias (IDIS), CIMUS, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain; Department of Physiology, CIMUS, University of Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Carlos Diéguez
- Instituto de Investigaciones Sanitarias (IDIS), CIMUS, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain; Department of Physiology, CIMUS, University of Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Angel Nadal
- Instituto de Bioingeniería and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Universidad Miguel Hernández, Elche, Spain
| | - Rubén Nogueiras
- Instituto de Investigaciones Sanitarias (IDIS), CIMUS, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain; Department of Physiology, CIMUS, University of Santiago de Compostela, Santiago de Compostela 15782, Spain.
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276
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Pais R, Rievaj J, Meek C, De Costa G, Jayamaha S, Alexander RT, Reimann F, Gribble F. Role of enteroendocrine L-cells in arginine vasopressin-mediated inhibition of colonic anion secretion. J Physiol 2016; 594:4865-78. [PMID: 27037495 PMCID: PMC5009784 DOI: 10.1113/jp272053] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/20/2016] [Indexed: 12/17/2022] Open
Abstract
Key points Arginine vasopressin (AVP) stimulates the release of enteroendocrine L‐cell derived hormones glucagon‐like peptide‐1 (GLP‐1) and peptide YY (PYY) in vitro from mouse and human colons. This is mediated by the AVP receptor 1B, which is highly enriched in colonic L‐cells and linked to the elevation of L‐cell calcium and cAMP concentrations. By means of Ussing chambers, we show that AVP reduced colonic anion secretion, although this was blocked by a specific neuropeptide Y receptor Y1 receptor antagonist, suggesting that L‐cell‐released PYY acts locally on the epithelium to modulate fluid balance. In human serum samples, PYY concentrations were higher in samples with raised osmolality and copeptin (surrogate marker for AVP). These findings describe, for the first time, the role of L‐cells in AVP regulated intestinal fluid secretion, potentially linking together hormonal control of blood volume and blood glucose levels, and thus adding to our understanding of the complex pathways involved in the gut hormonal response to different stimuli.
Abstract Arginine vasopressin (AVP) regulates fluid balance and blood pressure via AVP receptor (AVPR)2 in the kidney and AVP receptor 1A in vascular smooth muscle. Its role in intestinal function has received less attention. We hypothesized that enteroendocrine L‐cells producing glucagon‐like peptide 1 (GLP‐1) and peptide YY (PYY) may be a target of AVP and contribute to the control of fluid balance. Avpr1b expression was assessed by quantitative RT‐PCR on flourescence‐activated cell sorting‐isolated L‐ and control cells and was enriched in colonic L‐cells. AVP stimulated GLP‐1 and PYY release from primary cultured murine and human colonic cells and was associated with elevated calcium and cAMP concentrations in L‐cells as measured in cultures from GLU‐Cre/ROSA26‐GCaMP3 and GLU‐Epac2camps mice. An antagonist of AVPR1B reduced AVP‐triggered hormone secretion from murine and human cells. In Ussing chambers, basolaterally applied AVP reduced colonic anion secretion and this effect was blocked by a specific neuropeptide Y receptor Y1 (NPY1R) antagonist. In human serum, PYY concentrations were higher in samples with raised osmolality or copeptin (a surrogate marker for AVP). In conclusion, we propose that AVP activates L‐cell AVPR1B, causing GLP‐1 and PYY secretion. PYY in turn reduces colonic anion secretion via epithelial NPY1R. Our data suggest L‐cells are active players in the hypothalamic control of intestinal fluid homeostasis, providing a potential link between the regulation of blood volume/pressure/osmolality and blood glucose. Arginine vasopressin (AVP) stimulates the release of enteroendocrine L‐cell derived hormones glucagon‐like peptide‐1 (GLP‐1) and peptide YY (PYY) in vitro from mouse and human colons. This is mediated by the AVP receptor 1B, which is highly enriched in colonic L‐cells and linked to the elevation of L‐cell calcium and cAMP concentrations. By means of Ussing chambers, we show that AVP reduced colonic anion secretion, although this was blocked by a specific neuropeptide Y receptor Y1 receptor antagonist, suggesting that L‐cell‐released PYY acts locally on the epithelium to modulate fluid balance. In human serum samples, PYY concentrations were higher in samples with raised osmolality and copeptin (surrogate marker for AVP). These findings describe, for the first time, the role of L‐cells in AVP regulated intestinal fluid secretion, potentially linking together hormonal control of blood volume and blood glucose levels, and thus adding to our understanding of the complex pathways involved in the gut hormonal response to different stimuli.
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Affiliation(s)
- Ramona Pais
- The Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Juraj Rievaj
- The Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Claire Meek
- The Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Gayan De Costa
- Department of Clinical Biochemistry, Cambridge University Hospitals, Addenbrooke's Hospital, Cambridge, UK
| | - Samanthie Jayamaha
- Department of Clinical Biochemistry, Cambridge University Hospitals, Addenbrooke's Hospital, Cambridge, UK
| | - R Todd Alexander
- Departments of Paediatrics & Physiology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Frank Reimann
- The Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Fiona Gribble
- The Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
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277
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Thiebaud N, Llewellyn-Smith IJ, Gribble F, Reimann F, Trapp S, Fadool DA. The incretin hormone glucagon-like peptide 1 increases mitral cell excitability by decreasing conductance of a voltage-dependent potassium channel. J Physiol 2016; 594:2607-28. [PMID: 26931093 PMCID: PMC4865572 DOI: 10.1113/jp272322] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 02/25/2016] [Indexed: 02/06/2023] Open
Abstract
Key points The gut hormone called glucagon‐like peptide 1 (GLP‐1) is a strong moderator of energy homeostasis and communication between the peripheral organs and the brain. GLP‐1 signalling occurs in the brain; using a newly developed genetic reporter line of mice, we have discovered GLP‐synthesizing cells in the olfactory bulb. GLP‐1 increases the firing frequency of neurons (mitral cells) that encode olfactory information by decreasing activity of voltage‐dependent K channels (Kv1.3). Modifying GLP‐1 levels, either therapeutically or following the ingestion of food, could alter the excitability of neurons in the olfactory bulb in a nutrition or energy state‐dependent manner to influence olfactory detection or metabolic sensing. The results of the present study uncover a new function for an olfactory bulb neuron (deep short axon cells, Cajal cells) that could be capable of modifying mitral cell activity through the release of GLP‐1. This might be of relevance for the action of GLP‐1 mimetics now widely used in the treatment of diabetes.
Abstract The olfactory system is intricately linked with the endocrine system where it may serve as a detector of the internal metabolic state or energy homeostasis in addition to its classical function as a sensor of external olfactory information. The recent development of transgenic mGLU‐yellow fluorescent protein mice that express a genetic reporter under the control of the preproglucagon reporter suggested the presence of the gut hormone, glucagon‐like peptide (GLP‐1), in deep short axon cells (Cajal cells) of the olfactory bulb and its neuromodulatory effect on mitral cell (MC) first‐order neurons. A MC target for the peptide was determined using GLP‐1 receptor binding assays, immunocytochemistry for the receptor and injection of fluorescence‐labelled GLP‐1 analogue exendin‐4. Using patch clamp recording of olfactory bulb slices in the whole‐cell configuration, we report that GLP‐1 and its stable analogue exendin‐4 increase the action potential firing frequency of MCs by decreasing the interburst interval rather than modifying the action potential shape, train length or interspike interval. GLP‐1 decreases Kv1.3 channel contribution to outward currents in voltage clamp recordings as determined by pharmacological blockade of Kv1.3 or utilizing mice with Kv1.3 gene‐targeted deletion as a negative control. Because fluctuations in GLP‐1 concentrations monitored by the olfactory bulb can modify the firing frequency of MCs, olfactory coding could change depending upon nutritional or physiological state. As a regulator of neuronal activity, GLP‐1 or its analogue may comprise a new metabolic factor with a potential therapeutic target in the olfactory bulb (i.e. via intranasal delivery) for controlling an imbalance in energy homeostasis. The gut hormone called glucagon‐like peptide 1 (GLP‐1) is a strong moderator of energy homeostasis and communication between the peripheral organs and the brain. GLP‐1 signalling occurs in the brain; using a newly developed genetic reporter line of mice, we have discovered GLP‐synthesizing cells in the olfactory bulb. GLP‐1 increases the firing frequency of neurons (mitral cells) that encode olfactory information by decreasing activity of voltage‐dependent K channels (Kv1.3). Modifying GLP‐1 levels, either therapeutically or following the ingestion of food, could alter the excitability of neurons in the olfactory bulb in a nutrition or energy state‐dependent manner to influence olfactory detection or metabolic sensing. The results of the present study uncover a new function for an olfactory bulb neuron (deep short axon cells, Cajal cells) that could be capable of modifying mitral cell activity through the release of GLP‐1. This might be of relevance for the action of GLP‐1 mimetics now widely used in the treatment of diabetes.
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Affiliation(s)
- Nicolas Thiebaud
- The Florida State University, Department of Biological Science, Program in Neuroscience, Tallahassee, FL, USA
| | - Ida J Llewellyn-Smith
- Cardiovascular Medicine and Human Physiology, School of Medicine, Flinders University, Bedford Park, SA, Australia
| | - Fiona Gribble
- Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK
| | - Frank Reimann
- Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK
| | - Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology, and Pharmacology, University College London, London, UK.,Department of Surgery and Cancer, Imperial College London, London, UK
| | - Debra Ann Fadool
- The Florida State University, Department of Biological Science, Program in Neuroscience, Tallahassee, FL, USA.,The Florida State University, Institute of Molecular Biophysics, Tallahassee, FL, USA
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278
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Katsurada K, Yada T. Neural effects of gut- and brain-derived glucagon-like peptide-1 and its receptor agonist. J Diabetes Investig 2016; 7 Suppl 1:64-9. [PMID: 27186358 PMCID: PMC4854507 DOI: 10.1111/jdi.12464] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 12/21/2015] [Indexed: 12/17/2022] Open
Abstract
Glucagon‐like peptide‐1 (GLP‐1) is derived from both the enteroendocrine L cells and preproglucagon‐expressing neurons in the nucleus tractus solitarius (NTS) of the brain stem. As GLP‐1 is cleaved by dipeptidyl peptidase‐4 yielding a half‐life of less than 2 min, it is plausible that the gut‐derived GLP‐1, released postprandially, exerts its effects on the brain mainly by interacting with vagal afferent neurons located at the intestinal or hepatic portal area. GLP‐1 neurons in the NTS widely project in the central nervous system and act as a neurotransmitter. One of the physiological roles of brain‐derived GLP‐1 is restriction of feeding. GLP‐1 receptor agonists have recently been used to treat type 2 diabetic patients, and have been shown to exhibit pleiotropic effects beyond incretin action, which involve brain functions. GLP‐1 receptor agonist administered in the periphery is stable because of its resistance to dipeptidyl peptidase‐4, and is highly likely to act on the brain by passing through the blood–brain barrier (BBB), as well as interacting with vagal afferent nerves. Central actions of GLP‐1 have various roles including regulation of feeding, weight, glucose and lipid metabolism, cardiovascular functions, cognitive functions, and stress and emotional responses. In the present review, we focus on the source of GLP‐1 and the pathway by which peripheral GLP‐1 informs the brain, and then discuss recent findings on the central effects of GLP‐1 and GLP‐1 receptor agonists.
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Affiliation(s)
- Kenichi Katsurada
- Division of Integrative PhysiologyDepartment of PhysiologyJichi Medical University School of MedicineShimotsukeTochigiJapan; Division of Cardiovascular MedicineDepartment of Internal MedicineJichi Medical University School of MedicineShimotsukeTochigiJapan
| | - Toshihiko Yada
- Division of Integrative Physiology Department of Physiology Jichi Medical University School of Medicine Shimotsuke Tochigi Japan
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279
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Kanoski SE, Hayes MR, Skibicka KP. GLP-1 and weight loss: unraveling the diverse neural circuitry. Am J Physiol Regul Integr Comp Physiol 2016; 310:R885-95. [PMID: 27030669 DOI: 10.1152/ajpregu.00520.2015] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/26/2016] [Indexed: 02/07/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is currently one of the most promising biological systems for the development of effective obesity pharmacotherapies. Long-acting GLP-1 analogs potently reduce food intake and body weight, and recent discoveries reveal that peripheral administration of these drugs reduces food intake largely through humoral pathways involving direct action on brain GLP-1 receptors (GLP-1R). Thus, it is of critical importance to understand the neural systems through which GLP-1 and long-acting GLP-1 analogs reduce food intake and body weight. In this review, we discuss several neural, physiological, cellular and molecular, as well as behavioral mechanisms through which peripheral and central GLP-1R signaling reduces feeding. Particular attention is devoted to discussion regarding the numerous neural substrates through which GLP-1 and GLP-1 analogs act to reduce food intake and body weight, including various hypothalamic nuclei (arcuate nucleus of the hypothalamus, periventricular hypothalamus, lateral hypothalamic area), hindbrain nuclei (parabrachial nucleus, medial nucleus tractus solitarius), hippocampus (ventral subregion; vHP), and nuclei embedded within the mesolimbic reward circuitry [ventral tegmental area (VTA) and nucleus accumbens (NAc)]. In some of these nuclei [VTA, NAc, and vHP], GLP-1R activation reduces food intake and body weight without concomitant nausea responses, suggesting that targeting these specific pathways may be of particular interest for future obesity pharmacotherapy. The widely distributed neural systems through which GLP-1 and GLP-1 analogs act to reduce body weight highlight the complexity of the neural systems regulating energy balance, as well as the challenges for developing effective obesity pharmacotherapies that reduce feeding without producing parallel negative side effects.
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Affiliation(s)
- Scott E Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California;
| | - Matthew R Hayes
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia Pennsylvania; and
| | - Karolina P Skibicka
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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280
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D'Alessio D. Is GLP-1 a hormone: Whether and When? J Diabetes Investig 2016; 7 Suppl 1:50-5. [PMID: 27186356 PMCID: PMC4854505 DOI: 10.1111/jdi.12466] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 12/21/2015] [Indexed: 01/24/2023] Open
Abstract
Glucagon‐like peptide‐1 (GLP‐1) is a product of proglucagon cleavage synthesized in L cells in the intestinal mucosa, α‐cells in the pancreatic islet, and neurons in the nucleus of the solitary tract. GLP‐1 is essential for normal glucose tolerance and acts through a specific GLP‐1 receptor that is expressed by islet β‐cells as well as other cell types. Because plasma concentrations of GLP‐1 increase following meal ingestion it has been generally presumed that GLP‐1 acts as a hormone, communicating information from the intestine to the endocrine pancreas through the circulation. However, there are a number of problems with this model including low circulating concentrations of GLP‐1 in plasma, limited changes after meal ingestion and rapid metabolism in the plasma. Moreover, antagonism of systemic GLP‐1 action impairs insulin secretion in the fasting state, suggesting that the GLP‐1r is active even when plasma GLP‐1 levels are low and unchanging. Consistent with these observations, deletion of the GLP‐1r from islet β‐cells causes intolerance after IP or IV glucose, challenges that do not induce GLP‐1 secretion. Taken together, these data support a model whereby GLP‐1 acts through neural or paracrine mechanisms to regulate physiologic insulin secretion. In contrast, bariatric surgery seems to be a condition in which circulating GLP‐1 could have an endocrine effect. Both gastric bypass and sleeve gastrectomy are associated with substantial increases in postprandial GLP‐1 release and in these conditions interference with GLP‐1r signaling has a significant impact on glucose regulation after eating. Thus, with either bariatric surgery or treatment with long‐acting GLP‐1r agonists, circulating peptide mediates insulinotropic activity. Overall, a case can be made that physiologic actions of GLP‐1 are not hormonal, but that an endocrine mechanism of GLP‐1r activation can be co‐opted for therapeutics.
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Affiliation(s)
- David D'Alessio
- Division of Endocrinology, Metabolism and Nutrition Duke University Medical Center Durham North Carolina USA
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281
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Poudyal H. Mechanisms for the cardiovascular effects of glucagon-like peptide-1. Acta Physiol (Oxf) 2016; 216:277-313. [PMID: 26384481 DOI: 10.1111/apha.12604] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 07/25/2015] [Accepted: 09/10/2015] [Indexed: 12/16/2022]
Abstract
Over the past three decades, at least 10 hormones secreted by the enteroendocrine cells have been discovered, which directly affect the cardiovascular system through their innate receptors expressed in the heart and blood vessels or through a neural mechanism. Glucagon-like peptide-1 (GLP-1), an important incretin, is perhaps best studied of these gut-derived hormones with important cardiovascular effects. In this review, I have discussed the mechanism of GLP-1 release from the enteroendocrine L-cells and its physiological effects on the cardiovascular system. Current evidence suggests that GLP-1 has positive inotropic and chronotropic effects on the heart and may be important in preserving left ventricular structure and function by direct and indirect mechanisms. The direct effects of GLP-1 in the heart may be mediated through GLP-1R expressed in atria as well as arteries and arterioles in the left ventricle and mainly involve in the activation of multiple pro-survival kinases and enhanced energy utilization. There is also good evidence to support the involvement of a second, yet to be identified, GLP-1 receptor. Further, GLP-1(9-36)amide, which was previously thought to be the inactive metabolite of the active GLP-1(7-36)amide, may also have direct cardioprotective effects. GLP-1's action on GLP-1R expressed in the central nervous system, kidney, vasculature and the pancreas may indirectly contribute to its cardioprotective effects.
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Affiliation(s)
- H. Poudyal
- Department of Diabetes, Endocrinology and Nutrition; Graduate School of Medicine and Hakubi Centre for Advanced Research; Kyoto University; Kyoto Japan
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282
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Hansen HH, Barkholt P, Fabricius K, Jelsing J, Terwel D, Pyke C, Knudsen LB, Vrang N. The GLP-1 receptor agonist liraglutide reduces pathology-specific tau phosphorylation and improves motor function in a transgenic hTauP301L mouse model of tauopathy. Brain Res 2016; 1634:158-170. [DOI: 10.1016/j.brainres.2015.12.052] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 12/18/2015] [Accepted: 12/22/2015] [Indexed: 01/10/2023]
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283
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Zadeh-Tahmasebi M, Duca FA, Rasmussen BA, Bauer PV, Côté CD, Filippi BM, Lam TKT. Activation of Short and Long Chain Fatty Acid Sensing Machinery in the Ileum Lowers Glucose Production in Vivo. J Biol Chem 2016; 291:8816-24. [PMID: 26896795 DOI: 10.1074/jbc.m116.718460] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Indexed: 01/14/2023] Open
Abstract
Evidence continues to emerge detailing the myriad of ways the gut microbiota influences host energy homeostasis. Among the potential mechanisms, short chain fatty acids (SCFAs), the byproducts of microbial fermentation of dietary fibers, exhibit correlative beneficial metabolic effects in humans and rodents, including improvements in glucose homeostasis. The underlying mechanisms, however, remain elusive. We here report that one of the main bacterially produced SCFAs, propionate, activates ileal mucosal free fatty acid receptor 2 to trigger a negative feedback pathway to lower hepatic glucose production in healthy rats in vivo We further demonstrate that an ileal glucagon-like peptide-1 receptor-dependent neuronal network is necessary for ileal propionate and long chain fatty acid sensing to regulate glucose homeostasis. These findings highlight the potential to manipulate fatty acid sensing machinery in the ileum to regulate glucose homeostasis.
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Affiliation(s)
- Melika Zadeh-Tahmasebi
- From the Toronto General Research Institute and Department of Medicine, UHN, Toronto, Ontario M5G 1L7, the Departments of Physiology and
| | - Frank A Duca
- From the Toronto General Research Institute and Department of Medicine, UHN, Toronto, Ontario M5G 1L7
| | - Brittany A Rasmussen
- From the Toronto General Research Institute and Department of Medicine, UHN, Toronto, Ontario M5G 1L7, the Departments of Physiology and
| | - Paige V Bauer
- From the Toronto General Research Institute and Department of Medicine, UHN, Toronto, Ontario M5G 1L7, the Departments of Physiology and
| | - Clémence D Côté
- From the Toronto General Research Institute and Department of Medicine, UHN, Toronto, Ontario M5G 1L7, the Departments of Physiology and
| | - Beatrice M Filippi
- From the Toronto General Research Institute and Department of Medicine, UHN, Toronto, Ontario M5G 1L7
| | - Tony K T Lam
- From the Toronto General Research Institute and Department of Medicine, UHN, Toronto, Ontario M5G 1L7, the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario M5G 2C4, Canada
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284
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Bauer PV, Hamr SC, Duca FA. Regulation of energy balance by a gut-brain axis and involvement of the gut microbiota. Cell Mol Life Sci 2016; 73:737-55. [PMID: 26542800 PMCID: PMC11108299 DOI: 10.1007/s00018-015-2083-z] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 10/22/2015] [Accepted: 10/26/2015] [Indexed: 12/11/2022]
Abstract
Despite significant progress in understanding the homeostatic regulation of energy balance, successful therapeutic options for curbing obesity remain elusive. One potential target for the treatment of obesity is via manipulation of the gut-brain axis, a complex bidirectional communication system that is crucial in maintaining energy homeostasis. Indeed, ingested nutrients induce secretion of gut peptides that act either via paracrine signaling through vagal and non-vagal neuronal relays, or in an endocrine fashion via entry into circulation, to ultimately signal to the central nervous system where appropriate responses are generated. We review here the current hypotheses of nutrient sensing mechanisms of enteroendocrine cells, including the release of gut peptides, mainly cholecystokinin, glucagon-like peptide-1, and peptide YY, and subsequent gut-to-brain signaling pathways promoting a reduction of food intake and an increase in energy expenditure. Furthermore, this review highlights recent research suggesting this energy regulating gut-brain axis can be influenced by gut microbiota, potentially contributing to the development of obesity.
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Affiliation(s)
- Paige V Bauer
- Department of Medicine, Toronto General Research Institute, UHN, Toronto, ON, M5G 1L7, Canada
- Department of Physiology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Sophie C Hamr
- Department of Medicine, Toronto General Research Institute, UHN, Toronto, ON, M5G 1L7, Canada
- Department of Physiology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Frank A Duca
- Department of Medicine, Toronto General Research Institute, UHN, Toronto, ON, M5G 1L7, Canada.
- MaRS Centre, Toronto Medical Discovery Tower, Room 10-701H, 101 College Street, Toronto, ON, M5G 1L7, Canada.
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285
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Reimann F, Gribble FM. G protein-coupled receptors as new therapeutic targets for type 2 diabetes. Diabetologia 2016; 59:229-33. [PMID: 26661410 PMCID: PMC4705132 DOI: 10.1007/s00125-015-3825-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 11/09/2015] [Indexed: 11/30/2022]
Abstract
G protein-coupled receptors (GPCRs) in the gut-brain-pancreatic axis are key players in the postprandial control of metabolism and food intake. A number of intestinally located receptors have been implicated in the chemo-detection of ingested nutrients, and in the pancreatic islets and nervous system GPCRs play essential roles in the detection of many hormones and neurotransmitters. Because of the diversity, cell-specific expression and 'druggability' of the GPCR superfamily, these receptors are popular targets for therapeutic development. This review will outline current and potential future approaches to develop GPCR agonists for the treatment of type 2 diabetes. This review summarises a presentation given at the 'Novel approaches to treating type 2 diabetes' symposium at the 2015 annual meeting of the EASD. It is accompanied by a commentary by the Session Chair, Michael Nauck (DOI: 10.1007/s00125-015-3823-1 ).
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Affiliation(s)
- Frank Reimann
- Wellcome Trust-MRC Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Addenbrooke's Hospital Box 289, Hills Road, Cambridge, CB2 0QQ, UK
| | - Fiona M Gribble
- Wellcome Trust-MRC Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Addenbrooke's Hospital Box 289, Hills Road, Cambridge, CB2 0QQ, UK.
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286
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Oh DY, Olefsky JM. G protein-coupled receptors as targets for anti-diabetic therapeutics. Nat Rev Drug Discov 2016; 15:161-72. [DOI: 10.1038/nrd.2015.4] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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287
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Abstract
Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are the known incretin hormones in humans, released predominantly from the enteroendocrine K and L cells within the gut. Their secretion is regulated by a complex of integrated mechanisms involving direct contact for the activation of different chemo-sensors on the brush boarder of K and L cells and several indirect neuro-immuno-hormonal loops. The biological actions of GIP and GLP-1 are fundamental determinants of islet function and blood glucose homeostasis in health and type 2 diabetes. Moreover, there is increasing recognition that GIP and GLP-1 also exert pleiotropic extra-glycaemic actions, which may represent therapeutic targets for human diseases. In this review, we summarise current knowledge of the biology of incretin hormones in health and metabolic disorders and highlight the therapeutic potential of incretin hormones in metabolic regulation.
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Affiliation(s)
- Tongzhi Wu
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, 5000, Australia
| | - Christopher K Rayner
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, 5000, Australia.
- Centre of Research Excellence in Translating Nutritional Science into Good Health, The University of Adelaide, Adelaide, Australia.
| | - Michael Horowitz
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, 5000, Australia
- Centre of Research Excellence in Translating Nutritional Science into Good Health, The University of Adelaide, Adelaide, Australia
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288
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Laurent D, Vinet L, Lamprianou S, Daval M, Filhoulaud G, Ktorza A, Wang H, Sewing S, Juretschke HP, Glombik H, Meda P, Boisgard R, Nguyen DL, Stasiuk GJ, Long NJ, Montet X, Hecht P, Kramer W, Rutter GA, Hecksher-Sørensen J. Pancreatic β-cell imaging in humans: fiction or option? Diabetes Obes Metab 2016; 18:6-15. [PMID: 26228188 DOI: 10.1111/dom.12544] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 07/02/2015] [Accepted: 07/28/2015] [Indexed: 01/02/2023]
Abstract
Diabetes mellitus is a growing worldwide epidemic disease, currently affecting 1 in 12 adults. Treatment of disease complications typically consumes ∼10% of healthcare budgets in developed societies. Whilst immune-mediated destruction of insulin-secreting pancreatic β cells is responsible for Type 1 diabetes, both the loss and dysfunction of these cells underly the more prevalent Type 2 diabetes. The establishment of robust drug development programmes aimed at β-cell restoration is still hampered by the absence of means to measure β-cell mass prospectively in vivo, an approach which would provide new opportunities for understanding disease mechanisms and ultimately assigning personalized treatments. In the present review, we describe the progress towards this goal achieved by the Innovative Medicines Initiative in Diabetes, a collaborative public-private consortium supported by the European Commission and by dedicated resources of pharmaceutical companies. We compare several of the available imaging methods and molecular targets and provide suggestions as to the likeliest to lead to tractable approaches. Furthermore, we discuss the simultaneous development of animal models that can be used to measure subtle changes in β-cell mass, a prerequisite for validating the clinical potential of the different imaging tracers.
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Affiliation(s)
- D Laurent
- Biomarker Department, Clinical Imaging, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - L Vinet
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
| | - S Lamprianou
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
| | - M Daval
- Metabolic Diseases Department, Servier Research Institute, Suresnes, France
| | - G Filhoulaud
- Metabolic Diseases Department, Servier Research Institute, Suresnes, France
| | - A Ktorza
- Metabolic Diseases Department, Servier Research Institute, Suresnes, France
| | - H Wang
- Roche Pharma Research and Early Development, Innovation Center Basel, Basel, Switzerland
| | - S Sewing
- Roche Pharma Research and Early Development, Innovation Center Basel, Basel, Switzerland
| | - H-P Juretschke
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | - H Glombik
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | - P Meda
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - R Boisgard
- Commissariat à l'Energie Atomique, Equipe d'Imagerie Moléculaire Expérimentale, Orsay, France
| | - D L Nguyen
- Commissariat à l'Energie Atomique, Equipe d'Imagerie Moléculaire Expérimentale, Orsay, France
| | - G J Stasiuk
- Department of Chemistry, Imperial College London, London, UK
| | - N J Long
- Department of Chemistry, Imperial College London, London, UK
| | - X Montet
- Department of Radiology, Geneva University Hospital, Geneva, Switzerland
| | - P Hecht
- IMIDIA Project Office, Graz, Austria
| | - W Kramer
- Scientific Consultant for Sanofi Deutschland GmbH, Frankfurt am Main, Germany
| | - G A Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Hammersmith Hospital, London, UK
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289
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Hou Y, Ernst SA, Heidenreich K, Williams JA. Glucagon-like peptide-1 receptor is present in pancreatic acinar cells and regulates amylase secretion through cAMP. Am J Physiol Gastrointest Liver Physiol 2016; 310:G26-33. [PMID: 26542397 PMCID: PMC4698438 DOI: 10.1152/ajpgi.00293.2015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 10/27/2015] [Indexed: 01/31/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is a glucoincretin hormone that can act through its receptor (GLP-1R) on pancreatic β-cells and increase insulin secretion and production. GLP-1R agonists are used clinically to treat type 2 diabetes. GLP-1 may also regulate the exocrine pancreas at multiple levels, including inhibition through the central nervous system, stimulation indirectly through insulin, and stimulation directly on acinar cells. However, it has been unclear whether GLP-1R is present in pancreatic acini and what physiological functions these receptors regulate. In the current study we utilized GLP-1R knockout (KO) mice to study the role of GLP-1R in acinar cells. RNA expression of GLP-1R was detected in acutely isolated pancreatic acini. Acinar cell morphology and expression of digestive enzymes were not affected by loss of GLP-1R. GLP-1 induced amylase secretion in wild-type (WT) acini. In GLP-1R KO mice, this effect was abolished, whereas vasoactive intestinal peptide-induced amylase release in KO acini showed a pattern similar to that in WT acini. GLP-1 stimulated cAMP production and increased protein kinase A-mediated protein phosphorylation in WT acini, and these effects were absent in KO acini. These data show that GLP-1R is present in pancreatic acinar cells and that GLP-1 can regulate secretion through its receptor and cAMP signaling pathway.
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Affiliation(s)
- Yanan Hou
- 1Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan;
| | - Stephen A. Ernst
- 2Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan; and
| | - Kaeli Heidenreich
- 1Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan;
| | - John A. Williams
- 1Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan; ,3Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
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290
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Gaspari T, Brdar M, Lee HW, Spizzo I, Hu Y, Widdop RE, Simpson RW, Dear AE. Molecular and cellular mechanisms of glucagon-like peptide-1 receptor agonist-mediated attenuation of cardiac fibrosis. Diab Vasc Dis Res 2016; 13:56-68. [PMID: 26408644 DOI: 10.1177/1479164115605000] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Glucagon-like peptide-1 receptor agonists may have a role in modulation of cardiac fibrosis. Our study aimed to determine the effect of the glucagon-like peptide-1 receptor agonist liraglutide in obesity, hypertension and age-induced murine models of cardiac fibrosis and identify associated molecular mechanisms. METHODS C57Bl/6J mice on a high-fat diet and C57Bl/6J mice on a normal chow diet treated with angiotensin II were used to induce obesity and hypertension-mediated cardiac fibrosis, respectively. C57Bl/6J mice 20 months old were used to study age-induced cardiac fibrosis. Liraglutide treatment of 30 µg/kg/day-300 µg/kg s.c. twice daily was administered for 4 weeks. RESULTS Liraglutide treatment attenuated obesity, hypertension and age-induced increases in interstitial cardiac fibrosis and expression of inflammatory and oxidative stress markers. CONCLUSIONS These observations identify a potential role for liraglutide in the prevention of cardiac fibrosis and identify molecular mechanisms associated with these effects.
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Affiliation(s)
- Tracey Gaspari
- Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Melita Brdar
- Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Huey Wen Lee
- Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Iresha Spizzo
- Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Yunshan Hu
- Department of Medicine, Monash University, Melbourne, VIC, Australia
| | - Robert E Widdop
- Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Richard W Simpson
- Department of Medicine, Monash University, Melbourne, VIC, Australia
| | - Anthony E Dear
- Department of Medicine, Monash University, Melbourne, VIC, Australia
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291
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Sandoval D, Sisley SR. Brain GLP-1 and insulin sensitivity. Mol Cell Endocrinol 2015; 418 Pt 1:27-32. [PMID: 25724479 PMCID: PMC4547906 DOI: 10.1016/j.mce.2015.02.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 02/02/2015] [Accepted: 02/17/2015] [Indexed: 12/25/2022]
Abstract
Type 2 diabetes is often treated with a class of drugs referred to as glucagon-like peptide-1 (GLP-1) analogs. GLP-1 is a peptide secreted by the gut that acts through only one known receptor, the GLP-1 receptor. The primary function of GLP-1 is thought to be lowering of postprandial glucose levels. Indeed, medications utilizing this system, including the long-acting GLP-1 analogs liraglutide and exenatide, are beneficial in reducing both blood sugars and body weight. GLP-1 analogs were long presumed to affect glucose control through their ability to increase insulin levels through peripheral action on beta cells. However, multiple lines of data point to the ability of GLP-1 to act within the brain to alter glucose regulation. In this review we will discuss the evidence for a central GLP-1 system and the effects of GLP-1 in the brain on regulating multiple facets of glucose homeostasis including glucose tolerance, insulin production, insulin sensitivity, hepatic glucose production, muscle glucose uptake, and connections of the central GLP-1 system to the gut. Although the evidence indicates that GLP-1 receptors in the brain are not necessary for physiologic control of glucose regulation, we discuss the research showing a strong effect of acute manipulation of the central GLP-1 system on glucose control and how it is relevant to type 2 diabetic patients.
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Affiliation(s)
- Darleen Sandoval
- Department of Surgery, University of Michigan, Ann Arbor, MI, United States
| | - Stephanie R Sisley
- Department of Pediatrics, Division of Nutrition, Baylor College of Medicine, Houston, TX, United States.
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292
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Exenatide exerts a PKA-dependent positive inotropic effect in human atrial myocardium. J Mol Cell Cardiol 2015; 89:365-75. [DOI: 10.1016/j.yjmcc.2015.09.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 09/25/2015] [Accepted: 09/28/2015] [Indexed: 12/31/2022]
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293
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Renner S, Blutke A, Streckel E, Wanke R, Wolf E. Incretin actions and consequences of incretin-based therapies: lessons from complementary animal models. J Pathol 2015; 238:345-58. [DOI: 10.1002/path.4655] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/02/2015] [Accepted: 10/05/2015] [Indexed: 12/30/2022]
Affiliation(s)
- Simone Renner
- Gene Centre, Centre for Innovative Medical Models (CiMM) and German Centre for Diabetes Research (DZD); Ludwig-Maximilians-Universität München; Germany
| | - Andreas Blutke
- Institute of Veterinary Pathology, Centre for Clinical Veterinary Medicine; Ludwig-Maximilians-Universität München; Germany
| | - Elisabeth Streckel
- Gene Centre, Centre for Innovative Medical Models (CiMM) and German Centre for Diabetes Research (DZD); Ludwig-Maximilians-Universität München; Germany
| | - Rüdiger Wanke
- Institute of Veterinary Pathology, Centre for Clinical Veterinary Medicine; Ludwig-Maximilians-Universität München; Germany
| | - Eckhard Wolf
- Gene Centre, Centre for Innovative Medical Models (CiMM) and German Centre for Diabetes Research (DZD); Ludwig-Maximilians-Universität München; Germany
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294
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Abstract
The enteroendocrine system orchestrates how the body responds to the ingestion of foods, employing a diversity of hormones to fine-tune a wide range of physiological responses both within and outside the gut. Recent interest in gut hormones has surged with the realization that they modulate glucose tolerance and food intake through a variety of mechanisms, and such hormones are therefore excellent therapeutic candidates for the treatment of diabetes and obesity. Characterizing the roles and functions of different enteroendocrine cells is an essential step in understanding the physiology, pathophysiology, and therapeutics of the gut-brain-pancreas axis.
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Affiliation(s)
- Fiona M Gribble
- Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, and Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 0QQ, United Kingdom; ,
| | - Frank Reimann
- Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, and Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 0QQ, United Kingdom; ,
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295
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Duca FA, Bauer PV, Hamr SC, Lam TKT. Glucoregulatory Relevance of Small Intestinal Nutrient Sensing in Physiology, Bariatric Surgery, and Pharmacology. Cell Metab 2015. [PMID: 26212718 DOI: 10.1016/j.cmet.2015.07.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Emerging evidence suggests the gastrointestinal tract plays an important glucoregulatory role. In this perspective, we first review how the intestine senses ingested nutrients, initiating crucial negative feedback mechanisms through a gut-brain neuronal axis to regulate glycemia, mainly via reduction in hepatic glucose production. We then highlight how intestinal energy sensory mechanisms are responsible for the glucose-lowering effects of bariatric surgery, specifically duodenal-jejunal bypass, and the antidiabetic agents metformin and resveratrol. A better understanding of these pathways lays the groundwork for intestinally targeted drug therapy for the treatment of diabetes.
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Affiliation(s)
- Frank A Duca
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, ON M5G 1L7, Canada
| | - Paige V Bauer
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Sophie C Hamr
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Tony K T Lam
- Toronto General Research Institute and Department of Medicine, UHN, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada.
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296
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Trapp S, Cork SC. PPG neurons of the lower brain stem and their role in brain GLP-1 receptor activation. Am J Physiol Regul Integr Comp Physiol 2015; 309:R795-804. [PMID: 26290108 DOI: 10.1152/ajpregu.00333.2015] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 08/13/2015] [Indexed: 01/28/2023]
Abstract
Within the brain, glucagon-like peptide-1 (GLP-1) affects central autonomic neurons, including those controlling the cardiovascular system, thermogenesis, and energy balance. Additionally, GLP-1 influences the mesolimbic reward system to modulate the rewarding properties of palatable food. GLP-1 is produced in the gut and by hindbrain preproglucagon (PPG) neurons, located mainly in the nucleus tractus solitarii (NTS) and medullary intermediate reticular nucleus. Transgenic mice expressing glucagon promoter-driven yellow fluorescent protein revealed that PPG neurons not only project to central autonomic control regions and mesolimbic reward centers, but also strongly innervate spinal autonomic neurons. Therefore, these brain stem PPG neurons could directly modulate sympathetic outflow through their spinal inputs to sympathetic preganglionic neurons. Electrical recordings from PPG neurons in vitro have revealed that they receive synaptic inputs from vagal afferents entering via the solitary tract. Vagal afferents convey satiation to the brain from signals like postprandial gastric distention or activation of peripheral GLP-1 receptors. CCK and leptin, short- and long-term satiety peptides, respectively, increased the electrical activity of PPG neurons, while ghrelin, an orexigenic peptide, had no effect. These findings indicate that satiation is a main driver of PPG neuronal activation. They also show that PPG neurons are in a prime position to respond to both immediate and long-term indicators of energy and feeding status, enabling regulation of both energy balance and general autonomic homeostasis. This review discusses the question of whether PPG neurons, rather than gut-derived GLP-1, are providing the physiological substrate for the effects elicited by central nervous system GLP-1 receptor activation.
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Affiliation(s)
- Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Simon C Cork
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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297
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Nomoto H, Miyoshi H, Furumoto T, Oba K, Tsutsui H, Miyoshi A, Kondo T, Tsuchida K, Atsumi T, Manda N, Kurihara Y, Aoki S. A Comparison of the Effects of the GLP-1 Analogue Liraglutide and Insulin Glargine on Endothelial Function and Metabolic Parameters: A Randomized, Controlled Trial Sapporo Athero-Incretin Study 2 (SAIS2). PLoS One 2015; 10:e0135854. [PMID: 26284918 PMCID: PMC4540491 DOI: 10.1371/journal.pone.0135854] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/26/2015] [Indexed: 02/06/2023] Open
Abstract
Objectives GLP-1 improves hyperglycemia, and it has been reported to have favorable effects on atherosclerosis. However, it has not been fully elucidated whether GLP-1 is able to improve endothelial function in patients with type 2 diabetes. Therefore, we investigated the efficacy of the GLP-1 analogue, liraglutide on endothelial function and glycemic metabolism compared with insulin glargine therapy. Materials and Methods In this multicenter, prospective randomized parallel-group comparison study, 31 diabetic outpatients (aged 60.3 ± 10.3 years with HbA1c levels of 8.6 ± 0.8%) with current metformin and/or sulfonylurea treatment were enrolled and randomly assigned to receive liraglutide or glargine therapy once daily for 14 weeks. Flow mediated dilation (FMD), a comprehensive panel of hemodynamic parameters (Task Force Monitor), and serum metabolic markers were assessed before and after the treatment period. Results A greater reduction (worsening) in %FMD was observed in the glargine group, although this change was not statistically different from the liraglutide group (liraglutide; 5.7 to 5.4%, glargine 6.7 to 5.7%). The augmentation index, C-peptide index, derivatives of reactive oxygen metabolites and BMI were significantly improved in the liraglutide group. Central systolic blood pressure and NT-proBNP also tended to be improved in the liraglutide-treated group, while improvements in HbA1c levels were similar between groups. Cardiac index, blood pressure and most other metabolic parameters were not different. Conclusions Regardless of glycemic improvement, early liraglutide therapy did not affect endothelial function but may provide favorable effects on beta-cell function and cardioprotection in type 2 diabetics without advanced atherosclerosis. Trial Registration UMIN Clinical Trials Registry System as trial ID UMIN000005331.
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Affiliation(s)
- Hiroshi Nomoto
- Division of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hideaki Miyoshi
- Division of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
- * E-mail:
| | - Tomoo Furumoto
- Department of Cardiovascular Medicine, NTT East Japan Sapporo Hospital, Sapporo, Japan
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Koji Oba
- Department of Biostatistics, School of Public Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Interfaculty Initiative in Information Studies, The University of Tokyo, Tokyo, Japan
| | - Hiroyuki Tsutsui
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Arina Miyoshi
- Division of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Takuma Kondo
- Division of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | | | - Tatsuya Atsumi
- Division of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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298
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Dai FF, Bhattacharjee A, Liu Y, Batchuluun B, Zhang M, Wang XS, Huang X, Luu L, Zhu D, Gaisano H, Wheeler MB. A Novel GLP1 Receptor Interacting Protein ATP6ap2 Regulates Insulin Secretion in Pancreatic Beta Cells. J Biol Chem 2015; 290:25045-61. [PMID: 26272612 DOI: 10.1074/jbc.m115.648592] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Indexed: 11/06/2022] Open
Abstract
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.
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Affiliation(s)
- Feihan F Dai
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Alpana Bhattacharjee
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Ying Liu
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Battsetseg Batchuluun
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Ming Zhang
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Xinye Serena Wang
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Xinyi Huang
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Lemieux Luu
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Dan Zhu
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Herbert Gaisano
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Michael B Wheeler
- From the Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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299
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Distribution and characterisation of Glucagon-like peptide-1 receptor expressing cells in the mouse brain. Mol Metab 2015; 4:718-31. [PMID: 26500843 PMCID: PMC4588458 DOI: 10.1016/j.molmet.2015.07.008] [Citation(s) in RCA: 275] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 12/19/2022] Open
Abstract
Objective Although Glucagon-like peptide 1 is a key regulator of energy metabolism and food intake, the precise location of GLP-1 receptors and the physiological relevance of certain populations is debatable. This study investigated the novel GLP-1R-Cre mouse as a functional tool to address this question. Methods Mice expressing Cre-recombinase under the Glp1r promoter were crossed with either a ROSA26 eYFP or tdRFP reporter strain to identify GLP-1R expressing cells. Patch-clamp recordings were performed on tdRFP-positive neurons in acute coronal brain slices from adult mice and selective targeting of GLP-1R cells in vivo was achieved using viral gene delivery. Results Large numbers of eYFP or tdRFP immunoreactive cells were found in the circumventricular organs, amygdala, hypothalamic nuclei and the ventrolateral medulla. Smaller numbers were observed in the nucleus of the solitary tract and the thalamic paraventricular nucleus. However, tdRFP positive neurons were also found in areas without preproglucagon-neuronal projections like hippocampus and cortex. GLP-1R cells were not immunoreactive for GFAP or parvalbumin although some were catecholaminergic. GLP-1R expression was confirmed in whole-cell recordings from BNST, hippocampus and PVN, where 100 nM GLP-1 elicited a reversible inward current or depolarisation. Additionally, a unilateral stereotaxic injection of a cre-dependent AAV into the PVN demonstrated that tdRFP-positive cells express cre-recombinase facilitating virally-mediated eYFP expression. Conclusions This study is a comprehensive description and phenotypic analysis of GLP-1R expression in the mouse CNS. We demonstrate the power of combining the GLP-1R-CRE mouse with a virus to generate a selective molecular handle enabling future in vivo investigation as to their physiological importance. This transgenic mouse allows accurate evaluation of the distribution of GLP-1 receptor expressing cells. GLP-1 depolarises PVN, BNST and hippocampus neurons. GLP-1R expressing cells can be manipulated in vivo using this transgenic mouse.
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Key Words
- AP, area postrema
- BNST, bed nucleus stria terminalis
- Channelrhodopsin
- DMH, dorsomedial nucleus of the hypothalamus
- DMV, dorsal motor nucleus of the vagus
- Electrophysiology
- Ex-4, Exendin-4
- GFAP, glial fibrillary acidic protein
- GFP, green fluorescent protein
- GLP-1
- GLP-1, Glucagon-like peptide-1
- GLP-1R, Glucagon-like peptide-1 receptor
- Glucagon-like peptide-1 receptor
- NAc, nucleus accumbens
- NTS, nucleus of the solitary tract
- PARV, parvalbumin
- PPG
- PPG, preproglucagon
- PVN, paraventricular nucleus of the hypothalamus
- Preproglucagon
- TH, tyrosine hydroxylase
- VTA, ventral tegmental area
- YFP, yellow fluorescent protein
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300
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Spreckley E, Murphy KG. The L-Cell in Nutritional Sensing and the Regulation of Appetite. Front Nutr 2015; 2:23. [PMID: 26258126 PMCID: PMC4507148 DOI: 10.3389/fnut.2015.00023] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 07/06/2015] [Indexed: 12/25/2022] Open
Abstract
The gastrointestinal (GI) tract senses the ingestion of food and responds by signaling to the brain to promote satiation and satiety. Representing an important part of the gut-brain axis, enteroendocrine L-cells secrete the anorectic peptide hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) in response to the ingestion of food. The release of GLP-1 has multiple effects, including the secretion of insulin from pancreatic β-cells, decreased gastric emptying, and increased satiation. PYY also slows GI motility and reduces food intake. At least part of the gut-brain response seems to be due to direct sensing of macronutrients by L-cells, by mechanisms including specific nutrient-sensing receptors. Such receptors may represent possible pathways to target to decrease appetite and increase energy expenditure. Designing drugs or functional foods to exploit the machinery of these nutrient-sensing mechanisms may offer a potential approach for agents to treat obesity and metabolic disease.
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Affiliation(s)
- Eleanor Spreckley
- Section of Investigative Medicine, Department of Medicine, Imperial College London, Hammersmith Hospital , London , UK
| | - Kevin Graeme Murphy
- Section of Investigative Medicine, Department of Medicine, Imperial College London, Hammersmith Hospital , London , UK
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