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Zhang W, Wu L, Qu R, Liu T, Wang J, Tong Y, Bei W, Guo J, Hu X. Hesperidin activates the GLP-1R/cAMP-CREB/IRS2/PDX1 pathway to promote transdifferentiation of islet α cells into β cells Across the spectrum. Heliyon 2024; 10:e35424. [PMID: 39220963 PMCID: PMC11365324 DOI: 10.1016/j.heliyon.2024.e35424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/12/2024] [Accepted: 07/29/2024] [Indexed: 09/04/2024] Open
Abstract
Background and aims In all age, FoShou as a Chinese medicinal herb has been active in various kinds of Traditional Chinese medicine formula to treating diabetes. Hesperidin (HES), the main monomeric component of FoShou, has been extensively investigated for interventions with pathogenic mechanism of diabetes as well as subsequent treatment of associated complications. Islet β-cells have an essential effect on dynamically regulating blood sugar. Functional abnormalities in these cells and their death are strongly associated with the onset of diabetes. Therefore, induction of islet endocrine cell lineage re-editing for damaged βcell replenishment would be a promising therapeutic tool. Previously, it has been found that HES can protect islet β-cells in vivo, But, the regenerative function of HES in islet β cells and its role in promoting differential non-β cells transdifferentiation into β cells and cell fate rewriting associated mechanisms remain unclear.This work focused on investigating whether HES can induce islet α cells transdifferentiation into β cells for achieving damaged β cell regeneration and the causes and possible mechanisms involved in the process. Materials and methods In brief, 60 mg/kg/d streptozotocin (STZ) was administered intraperitoneally in each male C57bL/6J mouse raised by the high-sugar and high-fat diet (HFD) to create a diabetic mouse model with severe β-cell damage. After 28 consecutive days of HES treatment (160 mg/kg; 320 mg/kg; once daily, as appropriate). Tracing the dynamics of α as well as β cell transformation, together with β cells growth and apoptosis levels during treatment by cell lineage tracing. The self-enforcing transcriptional network on which the cell lineage is based is used as a clue to explore the underlying mechanisms. Guangdong Pharmaceutical University's Animal Experiment Ethics Committee (GDPulac2019180) approved all animal experiments. Results Localization by cell lineage we find that transdifferentiated newborn β-cells derived from α cells appeared in the islet endocrine cell mass of DM mice under HES'action. Compared to the model group, expressed by Tunel staining and CXCL10 levels the overall apoptosis rate of β-cells of the pancreas were reduced,the inflammatory infiltration feedback from HE staining were lower.Ki-67 positive cells showed enhanced β-cell proliferation. Decreased HbA1c and blood glucose contents, elevated C-Peptide and insulin contents which respond to ability of nascent beta cells. Also upregulated the mRNA levels of MafA, Ngn3, PDX-1, Pax4 and Arx. Moreover, increased the expression of TGR5/cAMP-CREB/GLP-1 in mouse intestinal tissues and GLP-1/GLP-1R and cAMP-CREB/IRS2/PDX-1 in pancreatic tissues. Conclusions HES directly affects β-cells, apart from being anti-apoptotic and reducing inflammatory infiltration. HES promotes GLP-1 release by intestinal L cells by activating the TGR5 receptor in DM mouse and regulating its response element CREB signaling. GLP-1 then uses the GLP-1/GLP-1R system to act on IRS2, IRS2 as a port to influence α precursor cells to express PDX-1, with the mobilization of Pax4 strong expression than Arx so that α cell lineage is finally reversed for achieving β cell endogenous proliferation.
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Affiliation(s)
- Wang Zhang
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Lele Wu
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Ru Qu
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Tianfeng Liu
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Jiliang Wang
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Ying Tong
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Weijian Bei
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Jiao Guo
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Xuguang Hu
- Guangdong Pharmaceutical University, Guangzhou, 510006, China
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Guo T, Zhang H, Luo Y, Yang X, Wang L, Zhang G. Global Trends and Frontier in Research on Pancreatic Alpha Cells: A Bibliometric Analysis from 2013 to 2023. CLIN INVEST MED 2024; 47:23-39. [PMID: 38958477 DOI: 10.3138/cim-2024-2744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
PURPOSE Over the past 20 years, much of the research on diabetes has focused on pancreatic beta cells. In the last 10 years, interest in the important role of pancreatic alpha cells in the pathogenesis of diabetes, which had previously received little attention, has grown. We aimed to summarize and visualize the hotspot and development trends of pancreatic alpha cells through bibliometric analysis and to provide research direction and future ideas for the treatment of diabetes and other islet-related diseases. METHODS We used two scientometric software packages (CiteSpace 6.1.R6 and VOSviewer1.6.18) to visualize the information and connection of countries, institutions, authors, and keywords in this field. RESULTS A total of 532 publications, published in 752 institutions in 46 countries and regions, were included in this analysis. The United States showed the highest output, accounting for 39.3% of the total number of published papers. The most active institution was Vanderbilt University, and the authors with highest productivity came from Ulster University. In recent years, research hotspots have concentrated on transdifferentiation, gene expression, and GLP-1 regulatory function. Visualization analysis shows that research hotspots mainly focus on clinical diseases as well as physiological and pathological mechanisms and related biochemical indicators. CONCLUSIONS This study provides a review and summary of the literature on pancreatic alpha cells through bibliometric and visual methods and shows research hotspot and development trends, which can guide future directions for research.
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Affiliation(s)
- Teng Guo
- Department of Endocrinology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
- Graduate School, Beijing University of Chinese Medicine, Beijing, China
| | - Haoling Zhang
- Institute of Clinical Pharmacology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yunpeng Luo
- Department of Endocrinology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
- Graduate School, Beijing University of Chinese Medicine, Beijing, China
| | - Xi Yang
- Department of Endocrinology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
- Graduate School, Beijing University of Chinese Medicine, Beijing, China
| | - Lidan Wang
- Department of Endocrinology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Guangde Zhang
- Department of Endocrinology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
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3
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Holter MM, Saikia M, Cummings BP. Alpha-cell paracrine signaling in the regulation of beta-cell insulin secretion. Front Endocrinol (Lausanne) 2022; 13:934775. [PMID: 35957816 PMCID: PMC9360487 DOI: 10.3389/fendo.2022.934775] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 06/28/2022] [Indexed: 01/14/2023] Open
Abstract
As an incretin hormone, glucagon-like peptide 1 (GLP-1) lowers blood glucose levels by enhancing glucose-stimulated insulin secretion from pancreatic beta-cells. Therapies targeting the GLP-1 receptor (GLP-1R) use the classical incretin model as a physiological framework in which GLP-1 secreted from enteroendocrine L-cells acts on the beta-cell GLP-1R. However, this model has come into question, as evidence demonstrating local, intra-islet GLP-1 production has advanced the competing hypothesis that the incretin activity of GLP-1 may reflect paracrine signaling of GLP-1 from alpha-cells on GLP-1Rs on beta-cells. Additionally, recent studies suggest that alpha-cell-derived glucagon can serve as an additional, albeit less potent, ligand for the beta-cell GLP-1R, thereby expanding the role of alpha-cells beyond that of a counterregulatory cell type. Efforts to understand the role of the alpha-cell in the regulation of islet function have revealed both transcriptional and functional heterogeneity within the alpha-cell population. Further analysis of this heterogeneity suggests that functionally distinct alpha-cell subpopulations display alterations in islet hormone profile. Thus, the role of the alpha-cell in glucose homeostasis has evolved in recent years, such that alpha-cell to beta-cell communication now presents a critical axis regulating the functional capacity of beta-cells. Herein, we describe and integrate recent advances in our understanding of the impact of alpha-cell paracrine signaling on insulin secretory dynamics and how this intra-islet crosstalk more broadly contributes to whole-body glucose regulation in health and under metabolic stress. Moreover, we explore how these conceptual changes in our understanding of intra-islet GLP-1 biology may impact our understanding of the mechanisms of incretin-based therapeutics.
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Affiliation(s)
- Marlena M. Holter
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
- *Correspondence: Marlena M. Holter,
| | - Mridusmita Saikia
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - Bethany P. Cummings
- School of Medicine, Department of Surgery, Center for Alimentary and Metabolic Sciences, University of California, Davis, Sacramento, CA, United States
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Borner T, Tinsley IC, Doyle RP, Hayes MR, De Jonghe BC. GLP-1 in diabetes care: Can glycemic control be achieved without nausea and vomiting? Br J Pharmacol 2021; 179:542-556. [PMID: 34363224 PMCID: PMC8810668 DOI: 10.1111/bph.15647] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 11/28/2022] Open
Abstract
Introduced less than two decades ago, glucagon-like peptide-1 receptor agonists (GLP-1RAs) rapidly re-shaped the field of type 2 diabetes (T2DM) care by providing glycemic control in tandem with weight loss. However, FDA-approved GLP-1RAs are often accompanied by nausea and emesis, and in some lean T2DM patients, by undesired anorexia. Importantly, the hypophagic and emetic effects of GLP-1RAs are caused by central GLP-1R activation. This review summarizes two different approaches to mitigate the incidence/severity of nausea and emesis related to GLP-1RAs: conjugation with vitamin B12, or related corrin-ring containing compounds ("corrination"), and development of dual-agonists of the GLP-1R with glucose dependent-insulinotropic polypeptide (GIP). Such approaches could lead to the generation of GLP-1RAs with improved therapeutic efficacy thus, decreasing treatment attrition, increasing patient compliance, and extending treatment to a broader population of T2DM patients. The data reviewed show that it is possible to pharmacologically separate emetic effects of GLP-1RAs from glucoregulatory action.
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Affiliation(s)
- Tito Borner
- Department of Biobehavioral Health Sciences, University of Pennsylvania, School of Nursing, Philadelphia, Pennsylvania, United States.,Department of Psychiatry, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Ian C Tinsley
- Department of Chemistry, Syracuse University, Syracuse, New York, United States
| | - Robert P Doyle
- Department of Chemistry, Syracuse University, Syracuse, New York, United States.,Departments of Medicine and Pharmacology, State University of New York, Upstate Medical University, Syracuse, New York, United States
| | - Matthew R Hayes
- Department of Biobehavioral Health Sciences, University of Pennsylvania, School of Nursing, Philadelphia, Pennsylvania, United States.,Department of Psychiatry, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Bart C De Jonghe
- Department of Biobehavioral Health Sciences, University of Pennsylvania, School of Nursing, Philadelphia, Pennsylvania, United States.,Department of Psychiatry, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
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5
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Jones S, Luo S, Dorton HM, Yunker AG, Angelo B, Defendis A, Monterosso JR, Page KA. Obesity and Dietary Added Sugar Interact to Affect Postprandial GLP-1 and Its Relationship to Striatal Responses to Food Cues and Feeding Behavior. Front Endocrinol (Lausanne) 2021; 12:638504. [PMID: 33868172 PMCID: PMC8044510 DOI: 10.3389/fendo.2021.638504] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 02/15/2021] [Indexed: 01/25/2023] Open
Abstract
It has been hypothesized that the incretin hormone, glucagon-like peptide-1 (GLP-1), decreases overeating by influencing mesolimbic brain regions that process food-cues, including the dorsal striatum. We previously showed that habitual added sugar intake was associated with lower glucose-induced circulating GLP-1 and a greater striatal response to high calorie food cues in lean individuals. Less is known about how dietary added sugar and obesity may interact to affect postprandial GLP-1 and its relationship to striatal responses to food cues and feeding behavior. The current study aimed to expand upon previous research by assessing how circulating GLP-1 and striatal food cue reactivity are affected by acute glucose consumption in participants with varied BMIs and amounts of habitual consumption of added sugar. This analysis included 72 participants from the Brain Response to Sugar Study who completed two study visits where they consumed either plain water or 75g glucose dissolved in water (order randomized; both drinks were flavored with non-caloric cherry flavoring) and underwent repeated blood sampling, a functional magnetic resonance imaging (fMRI) based food-cue task, and an ad-libitum buffet meal. Correlations between circulating GLP-1 levels, striatal food-cue reactivity, and food intake were assessed, and interactions between obesity and added sugar on GLP-1 and striatal responses were examined. An interaction between BMI and dietary added sugar was associated with reduced post-glucose GLP-1 secretion. Participants who were obese and consumed high levels of added sugar had the smallest increase in plasma GLP-1 levels. Glucose-induced GLP-1 secretion was correlated with lower dorsal striatal reactivity to high-calorie versus low-calorie food-cues, driven by an increase in reactivity to low calorie food-cues. The increase in dorsal striatal reactivity to low calorie food-cues was negatively correlated with sugar consumed at the buffet. These findings suggest that an interaction between obesity and dietary added sugar intake is associated with additive reductions in postprandial GLP-1 secretion. Additionally, the results suggest that changes to dorsal striatal food cue reactivity through a combination of dietary added sugar and obesity may affect food consumption.
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Affiliation(s)
- Sabrina Jones
- Division of Endocrinology, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Keck School of Medicine, Diabetes and Obesity Research Institute, University of Southern California, Los Angeles, CA, United States
| | - Shan Luo
- Division of Endocrinology, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Keck School of Medicine, Diabetes and Obesity Research Institute, University of Southern California, Los Angeles, CA, United States
- Department of Psychology, University of Southern California, Los Angeles, CA, United States
| | - Hilary M. Dorton
- Keck School of Medicine, Diabetes and Obesity Research Institute, University of Southern California, Los Angeles, CA, United States
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
| | - Alexandra G. Yunker
- Division of Endocrinology, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Keck School of Medicine, Diabetes and Obesity Research Institute, University of Southern California, Los Angeles, CA, United States
| | - Brendan Angelo
- Division of Endocrinology, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Keck School of Medicine, Diabetes and Obesity Research Institute, University of Southern California, Los Angeles, CA, United States
| | - Alexis Defendis
- Division of Endocrinology, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Keck School of Medicine, Diabetes and Obesity Research Institute, University of Southern California, Los Angeles, CA, United States
| | - John R. Monterosso
- Department of Psychology, University of Southern California, Los Angeles, CA, United States
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
| | - Kathleen A. Page
- Division of Endocrinology, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Keck School of Medicine, Diabetes and Obesity Research Institute, University of Southern California, Los Angeles, CA, United States
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
- *Correspondence: Kathleen A. Page,
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6
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Jones S, Hyde A, Davidson TL. Reframing appetitive reinforcement learning and reward valuation as effects mediated by hippocampal-dependent behavioral inhibition. Nutr Res 2020; 79:1-12. [PMID: 32544728 DOI: 10.1016/j.nutres.2020.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 04/13/2020] [Accepted: 05/04/2020] [Indexed: 02/06/2023]
Abstract
Traditional theories of neuroeconomics focus on reinforcement learning and reward value. We propose here a novel reframing of reinforcement learning and motivation that includes a hippocampal-dependent regulatory mechanism which balances cue-induced behavioral excitation with behavioral inhibition. This mechanism enables interoceptive cues produced by respective food or drug satiety to antagonize the ability of excitatory food- and drug-related environmental cues to retrieve the memories of food and drug reinforcers, thereby suppressing the power of those cues to evoke appetitive behavior. When the operation of this mechanism is impaired, ability of satiety signals to inhibit appetitive behavior is weakened because the relative balance between inhibition and simple excitation is shifted toward increased retrieval of food and drug memories by environmental cues. In the present paper, we (1) describe the associative processes that constitute this mechanism of hippocampal-dependent behavior inhibition; (2) describe how a prevailing obesity-promoting diet and drugs of abuse produce hippocampal pathophysiologies that can selectively impair this inhibitory function; and (3) propose how glucagon-like peptide 1 (GLP-1), an incretin hormone that is recognized as an important satiety signal, may work to protect the hippocampal-dependent inhibition. Our perspective may add to neuroscientific and neuroeconomic analyses of both overeating and drug abuse by outlining the role of hippocampal-dependent memory processes in the control of both food and drug seeking behaviors. In addition, this view suggests that consideration should be given to diet- and drug induced hippocampal pathophysiologies, as potential novel targets for the treatment of dysregulated energy and drug intake.
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Affiliation(s)
- Sabrina Jones
- Diabetes and Obesity Research Institute, Internal Medicine, Division of Endocrinology, University of Southern California, Los Angeles, CA, United States
| | - Alexia Hyde
- Center for Behavioral Neuroscience, Department of Psychology, American University, Washington, DC, United States
| | - Terry L Davidson
- Center for Behavioral Neuroscience, Department of Psychology, American University, Washington, DC, United States.
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Chia CW, Egan JM. Incretins in obesity and diabetes. Ann N Y Acad Sci 2019; 1461:104-126. [PMID: 31392745 PMCID: PMC10131087 DOI: 10.1111/nyas.14211] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/13/2019] [Accepted: 07/18/2019] [Indexed: 12/11/2022]
Abstract
Incretins are hormones secreted from enteroendocrine cells after nutrient intake that stimulate insulin secretion from β cells in a glucose-dependent manner. Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are the only two known incretins. Dysregulation of incretin secretion and actions are noted in diseases such as obesity and diabetes. In this review, we first summarize our traditional understanding of the physiology of GIP and GLP-1, and our current knowledge of the relationships between GIP and GLP-1 and obesity and diabetes. Next, we present the results from major randomized controlled trials on the use of GLP-1 receptor agonists for managing type 2 diabetes, and emerging data on treating obesity and prediabetes. We conclude with a glimpse of the future with possible complex interactions between nutrients, gut microbiota, the endocannabinoid system, and enteroendocrine cells.
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Affiliation(s)
- Chee W Chia
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Josephine M Egan
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
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8
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Borner T, Liberini CG, Lutz TA, Riediger T. Brainstem GLP-1 signalling contributes to cancer anorexia-cachexia syndrome in the rat. Neuropharmacology 2018; 131:282-290. [DOI: 10.1016/j.neuropharm.2017.12.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/11/2017] [Accepted: 12/11/2017] [Indexed: 02/07/2023]
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Central glucagon like peptide-1 inhibits reflex swallowing elicited by the superior laryngeal nerve via caudal brainstem in the rat. Brain Res 2017; 1671:26-32. [PMID: 28693820 DOI: 10.1016/j.brainres.2017.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/30/2017] [Accepted: 07/04/2017] [Indexed: 02/05/2023]
Abstract
The effects of glucagon like peptide-1 (GLP-1) on reflex swallowing were examined using anaesthetized rats. GLP-1 was injected into the dorsal vagal complex (DVC) using glass micropipettes. Swallowing was induced by repeated electrical stimulation of the central cut end of the superior laryngeal nerve (SLN) and was identified by the electromyogram lead penetrated in the mylohyoide muscle through bipolar electrodes. Microinjection of GLP-1 into the medial DVC (M-DVC) increased the frequency of swallowing during the electrical stimulation of the SLN and extended the latency of the first swallowing. Microinjection of GLP-1 into the lateral DVC (L-DVC) did not change the frequency of swallowing or the latency of the first swallowing. Neither the injection of vehicle into the M-DVC nor L-DVC affected swallowing frequency. Pre-injection of exendin (5-39), a GLP-1 receptor antagonist, attenuated the degree of suppression of swallowing frequency induced by the administration of GLP-1 in addition to shortening the latency of the first swallowing. To identify the effective site of GLP-1, lesion experiments were performed. Electrical lesion of the commissural part of the NTS (cNTS) and the vacuum removal of the area postrema (AP) did not affect the inhibition of reflex swallowing induced by the injection of GLP-1 into the M-DVC. Electrical lesion of the medial nucleus of the NTS (mNTS) and its vicinity abolished the inhibitory effects of swallowing induced by the injection of GLP-1. These results suggest that GLP-1 inhibits reflex swallowing via the mNTS in the dorsal medulla.
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Fava GE, Dong EW, Wu H. Intra-islet glucagon-like peptide 1. J Diabetes Complications 2016; 30:1651-1658. [PMID: 27267264 PMCID: PMC5050074 DOI: 10.1016/j.jdiacomp.2016.05.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 05/14/2016] [Accepted: 05/17/2016] [Indexed: 02/06/2023]
Abstract
PURPOSE Glucagon-like peptide-1 (GLP-1) is originally identified in the gut as an incretin hormone, and it is potent in stimulating insulin secretion in the pancreas. However, increasing evidence suggests that GLP-1 is also produced locally within pancreatic islets. This review focuses on the past and current discoveries regarding intra-islet GLP-1 production and its functions. MAIN FINDINGS There has been a long-standing debate with regard to whether GLP-1 is produced in the pancreatic α cells. Early controversies lead to the widely accepted conclusion that the vast majority of proglucagon is processed to form glucagon in the pancreas, whereas an insignificant amount is cleaved to produce GLP-1. With technological advancements, recent studies have shown that bioactive GLP-1 is produced locally in the pancreas, and the expression and secretion of GLP-1 within islets are regulated by various factors such as cytokines, hyperglycemia, and β cell injury. CONCLUSIONS GLP-1 is produced by the pancreatic α cells, and it is fully functional as an incretin. Therefore, intra-islet GLP-1 may exert insulinotropic and glucagonostatic effects locally via paracrine and/or autocrine actions, under both normal and diabetic conditions.
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Affiliation(s)
- Genevieve E Fava
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States
| | - Emily W Dong
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States
| | - Hongju Wu
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States.
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Gilor C, Rudinsky AJ, Hall MJ. New Approaches to Feline Diabetes Mellitus: Glucagon-like peptide-1 analogs. J Feline Med Surg 2016; 18:733-43. [PMID: 27562982 PMCID: PMC11148896 DOI: 10.1177/1098612x16660441] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
CLINICAL RELEVANCE Incretin-based therapies are revolutionizing the field of human diabetes mellitus (DM) by replacing insulin therapy with safer and more convenient long-acting drugs. MECHANISM OF ACTION Incretin hormones (glucagon-like peptide-1 [GLP-1] and glucose-dependent insulinotropic peptide [GIP]) are secreted from the intestinal tract in response to the presence of food in the intestinal lumen. GLP-1 delays gastric emptying and increases satiety. In the pancreas, GLP-1 augments insulin secretion and suppresses glucagon secretion during hyperglycemia in a glucose-dependent manner. It also protects beta cells from oxidative and toxic injury and promotes expansion of beta cell mass. ADVANTAGES Clinical data have revealed that GLP-1 analog drugs are as effective as insulin in improving glycemic control while reducing body weight in people suffering from type 2 DM. Furthermore, the incidence of hypoglycemia is low with these drugs because of their glucose-dependent mechanism of action. Another significant advantage of these drugs is their duration of action. While insulin injections are administered at least once daily, long-acting GLP-1 analogs have been developed as once-a-week injections and could potentially be administered even less frequently than that in diabetic cats. OUTLINE This article reviews the physiology of incretin hormones, and the pharmacology and use of GLP-1 analogs, with emphasis on recent research in cats. Further therapies that are based on incretin hormones, such as DPP-4 inhibitors, are also briefly discussed, as are some other treatment modalities that are currently under investigation.
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Affiliation(s)
- Chen Gilor
- University of California School of Veterinary Medicine, 2118A Tupper Hall, Davis, CA 95616, USA
| | - Adam J Rudinsky
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Melanie J Hall
- Sheridan Animal Hospital & Veterinary Specialists of Western New York, 2288 Sheridan Drive, Buffalo, NY 14223, USA
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Li SK, Zhu D, Gaisano HY, Brubaker PL. Role of vesicle-associated membrane protein 2 in exocytosis of glucagon-like peptide-1 from the murine intestinal L cell. Diabetologia 2014; 57:809-18. [PMID: 24356748 DOI: 10.1007/s00125-013-3143-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 11/22/2013] [Indexed: 12/27/2022]
Abstract
AIMS/HYPOTHESIS Glucagon-like peptide-1 (GLP-1), secreted by the enteroendocrine L cell, is an incretin hormone that potently stimulates insulin secretion. Although signalling pathways promoting GLP-1 release are well characterised, the mechanisms by which GLP-1-containing granules fuse to the L cell membrane are unknown. As soluble NSF attachment proteins (SNAREs) are known to mediate granule-membrane fusion, the role of vesicle-associated membrane proteins (VAMPs) in GLP-1 exocytosis was examined. METHODS SNARE expression was determined in murine GLUTag L cells by RT-PCR and immunoblot and in primary murine L cells by immunofluorescence. Co-immunoprecipitation was used to examine SNARE interactions, while tetanus toxin (TetX)-mediated cleavage of VAMP was used with a GLP-1 secretion assay and total internal reflection fluorescence microscopy to determine the role of VAMP2 in exocytosis. RESULTS VAMP2 was expressed in murine L cells and localised to secretory granules in GLUTag cells. VAMP1/3 and the core membrane proteins syntaxin1a and synaptosomal-associated protein 25 kDa (SNAP25) were also detected. TetX cleaved VAMPs in GLUTag cells. However, only VAMP2 interacted with syntaxin1a, as did SNAP25 and Munc18-1. TetX treatment of GLUTag cells prevented glucose-dependent insulinotrophic peptide- and oleic-acid-stimulated GLP-1 secretion (p < 0.05-0.01), as well as K(+)-stimulated single-cell exocytosis (p < 0.05-0.001), while TetX-resistant VAMP2 expression rescued GLP-1 secretion (p < 0.01-0.001). CONCLUSIONS/INTERPRETATION Together, these findings indicate an essential role for VAMP2 in GLP-1 exocytosis from the GLUTag L cell in response to a variety of established secretagogues. An improved understanding of the mechanisms governing the release of GLP-1 may lead to new therapeutic approaches to enhance the levels of this incretin hormone in patients with type 2 diabetes.
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Affiliation(s)
- Samantha K Li
- Department of Physiology, Medical Sciences Building, 1 King's College Circle, University of Toronto, Toronto, ON, M5S 1A8, Canada
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Immunohistochemical Study on Glucagon-Like Peptide-1(GLP-1) and Pituitary Adenylate Cyclase Activating Peptide (PACAP) in the Small Intestine of <i>Muscovy </i>Duck during the Prehatching and Posthatching Periods. J Poult Sci 2014. [DOI: 10.2141/jpsa.0120167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Gilor C, Gilor S, Graves TK, Borst LB, Labelle P, Ridge TK, Santoro D, Dossin O. Distribution of K and L cells in the feline intestinal tract. Domest Anim Endocrinol 2013; 45:49-54. [PMID: 23751572 DOI: 10.1016/j.domaniend.2013.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/23/2013] [Accepted: 04/26/2013] [Indexed: 12/25/2022]
Abstract
Glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide (GLP)-1 and GLP-2 are hormones secreted from specialized K cells (GIP) and L cells (GLP-1, GLP-2) in the intestinal mucosa. These hormones play major roles in health and disease by modulating insulin secretion, satiety, and multiple intestinal functions. The aim of this study was to describe the distribution of K cells and L cells in the intestines of healthy cats. Samples of duodenum, mid-jejunum, ileum, cecum, and colon were collected from 5 cats that were euthanized for reasons unrelated to this study and had no gross or histologic evidence of gastrointestinal disease. Samples stained with rabbit-anti-porcine GIP, mouse-anti-(all mammals) GLP-1, or rabbit-anti-(all mammals) GLP-2 antibodies were used to determine the number of cells in 15 randomly selected 400× microscopic fields. In contrast to other mammals (eg, dogs) in which K cells are not present in the ileum and aborally, GIP-expressing cells are abundant throughout the intestines in cats (>6/high-power field in the ileum). Cells expressing GLP-1 or GLP-2 were most abundant in the ileum (>9/high-power field) as in other mammals, but, although GLP-1-expressing cells were abundant throughout the intestines, GLP-2-expressing cells were rarely found in the duodenum. In conclusion, the distribution of GIP-secreting K cells in cats is different from the distribution of K cells that is described in other mammals. The difference in distribution of GLP-2- and GLP-1-expressing cells suggests that more than 1 distinct population of L cells is present in cats.
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Affiliation(s)
- C Gilor
- Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA.
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Physiology and emerging biochemistry of the glucagon-like peptide-1 receptor. EXPERIMENTAL DIABETES RESEARCH 2012; 2012:470851. [PMID: 22666230 PMCID: PMC3359799 DOI: 10.1155/2012/470851] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Accepted: 01/25/2012] [Indexed: 12/16/2022]
Abstract
The glucagon-like peptide-1 (GLP-1) receptor is one of the best validated therapeutic targets for the treatment of type 2 diabetes mellitus (T2DM). Over several years, the accumulation of basic, translational, and clinical research helped define the physiologic roles of GLP-1 and its receptor in regulating glucose homeostasis and energy metabolism. These efforts provided much of the foundation for pharmaceutical development of the GLP-1 receptor peptide agonists, exenatide and liraglutide, as novel medicines for patients suffering from T2DM. Now, much attention is focused on better understanding the molecular mechanisms involved in ligand induced signaling of the GLP-1 receptor. For example, advancements in biophysical and structural biology techniques are being applied in attempts to more precisely determine ligand binding and receptor occupancy characteristics at the atomic level. These efforts should better inform three-dimensional modeling of the GLP-1 receptor that will help inspire more rational approaches to identify and optimize small molecule agonists or allosteric modulators targeting the GLP-1 receptor. This article reviews GLP-1 receptor physiology with an emphasis on GLP-1 induced signaling mechanisms in order to highlight new molecular strategies that help determine desired pharmacologic characteristics for guiding development of future nonpeptide GLP-1 receptor activators.
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Vrang N, Larsen PJ. Preproglucagon derived peptides GLP-1, GLP-2 and oxyntomodulin in the CNS: role of peripherally secreted and centrally produced peptides. Prog Neurobiol 2010; 92:442-62. [PMID: 20638440 DOI: 10.1016/j.pneurobio.2010.07.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 07/01/2010] [Accepted: 07/10/2010] [Indexed: 12/16/2022]
Abstract
The scientific understanding of preproglucagon derived peptides has provided people with type 2 diabetes with two novel classes of glucose lowering agents, the dipeptidyl peptidase IV (DPP-IV) inhibitors and GLP-1 receptor agonists. For the scientists, the novel GLP-1 agonists, and DPP-IV inhibitors have evolved as useful tools to understand the role of the preproglucagon derived peptides in normal physiology and disease. However, the overwhelming interest attracted by GLP-1 analogues as potent incretins has somewhat clouded the efforts to understand the importance of preproglucagon derived peptides in other physiological contexts. In particular, our neurobiological understanding of the preproglucagon expressing neuronal pathways in the central nervous system as well as the degree to which central GLP-1 receptors are targeted by peripherally administered GLP-1 receptor agonists is still fairly limited. The role of GLP-1 as an anorectic neurotransmitter is well recognized, but clarification of the neuronal targets and physiological basis of this response is further warranted, as is the mapping of GLP-1 sensitive neurons involved in a variety of neuroendocrine and behavioral responses. Further recent evidence points to GLP-1 as a central neuropeptide with neuroprotective capabilities potentially mitigating a wide array of neurodegenerative conditions. It is the aim of the present review to summarize our current understanding of preproglucagon derived peptides as neurotransmitters in the central nervous system.
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Affiliation(s)
- Niels Vrang
- Gubra ApS, Ridebanevej 12, 1870 Frederiksberg, Denmark.
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Targeting the TGR5-GLP-1 pathway to combat type 2 diabetes and non-alcoholic fatty liver disease. ACTA ACUST UNITED AC 2010; 34:270-3. [DOI: 10.1016/j.gcb.2010.03.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 03/23/2010] [Indexed: 01/22/2023]
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Neuroprotection of geniposide against hydrogen peroxide induced PC12 cells injury: involvement of PI3 kinase signal pathway. Acta Pharmacol Sin 2009; 30:159-65. [PMID: 19151742 DOI: 10.1038/aps.2008.25] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
AIM Oxidative stress plays a critical role in the pathogenic cascade leading to neuronal degeneration in AD. Consequently, the induction of endogenous antioxidative proteins by antioxidants seems to be a very reasonable strategy for delaying the disease's progression. In previous work, we identified the neurotrophic and neuroprotective effects of geniposide, which result from the activation of glucagon-like peptide 1 receptor (GLP-1R). In this study, we explore the role of PI3 kinase signaling pathway in the neuroprotection of geniposide in PC12 cells. METHODS Cell viability was determined by MTT assay. Apoptosis was detected by Hoechst and PI double staining. The protein expression of Bcl-2 and phosphorylation of Akt308, Akt473, GSK-3beta, and PDK1 was measured by Western blot. RESULTS Geniposide induced the expression of the antiapoptotic protein Bcl-2, which inhibited apoptosis in PC12 cells induced by H(2)O(2), and this effect could be inhibited by preincubation with LY294002, a selective inhibitor of PI3K. Furthermore, geniposide enhanced the phosphorylation of Akt308, Akt473, GSK-3beta and PDK1 under conditions of oxidative stress. CONCLUSION These results demonstrate that the PI3K signaling pathway is involved in the neuroprotection of geniposide in PC12 cells against the oxidative damage induced by H(2)O(2) in PC12 cells.
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Abstract
The glucagon gene is expressed not only in the alpha cells of the pancreatic islets but also in the endocrine cells of the intestinal epithelium (so-called L-cells), and in certain neurons of the brain stem. Whereas in the pancreas, glucagon, the hyperglycaemic hormone, is cleaved out of the 160 amino acid precursor, proglucagon, leaving behind proglucagon fragments (PG 1-30 and PG 72-158, the so-called major proglucagon fragment (MPGF)) that are probably inactive, the intestinal processing leads to the formation of glicentin (PG 1-69; action uncertain) and glucagon-like peptides 1 (PG 78-107amide, a potent incretin homone, regulating insulin secretion, glucagon secretion, gastrointestinal motility and appetite) and 2 (PG 126-158, a regulator of gut mucosal growth and integrity). The two prohormone convertases PC2 and PC1/3, respectively, are responsible for the differential processing. After their release, the hormones are eliminated mainly in the kidneys, but both GLP-2 and in particular GLP-1, but not glucagon, are metabolized both locally and in the circulation and liver by dipeptidyl peptidase 4 (DPP-4) which inactivates the peptides, suggesting that GLP-1 acts locally rather than in an endocrine manner. A number of transcription factors have been identified that can at least partly explain the differential cellular expression of the glucagon gene as well as the differential tissue-specific processing of the precursor.
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Affiliation(s)
- Jens Juul Holst
- Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, 2200, Copenhagen, Denmark.
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Abstract
Glucagon-like peptide 1 (GLP-1) is a 30-amino acid peptide hormone produced in the intestinal epithelial endocrine L-cells by differential processing of proglucagon, the gene which is expressed in these cells. The current knowledge regarding regulation of proglucagon gene expression in the gut and in the brain and mechanisms responsible for the posttranslational processing are reviewed. GLP-1 is released in response to meal intake, and the stimuli and molecular mechanisms involved are discussed. GLP-1 is extremely rapidly metabolized and inactivated by the enzyme dipeptidyl peptidase IV even before the hormone has left the gut, raising the possibility that the actions of GLP-1 are transmitted via sensory neurons in the intestine and the liver expressing the GLP-1 receptor. Because of this, it is important to distinguish between measurements of the intact hormone (responsible for endocrine actions) or the sum of the intact hormone and its metabolites, reflecting the total L-cell secretion and therefore also the possible neural actions. The main actions of GLP-1 are to stimulate insulin secretion (i.e., to act as an incretin hormone) and to inhibit glucagon secretion, thereby contributing to limit postprandial glucose excursions. It also inhibits gastrointestinal motility and secretion and thus acts as an enterogastrone and part of the "ileal brake" mechanism. GLP-1 also appears to be a physiological regulator of appetite and food intake. Because of these actions, GLP-1 or GLP-1 receptor agonists are currently being evaluated for the therapy of type 2 diabetes. Decreased secretion of GLP-1 may contribute to the development of obesity, and exaggerated secretion may be responsible for postprandial reactive hypoglycemia.
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Affiliation(s)
- Jens Juul Holst
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
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Abstract
Post-translational proteolytic processing of the preproglucagon gene in the gut results in the formation of glucagon-like peptide 1 (GLP-1). Owing to its glucose-dependent insulinotropic effect, this hormone was postulated to primarily act as an incretin, i.e. to augment insulin secretion after oral glucose or meal ingestion. In addition, GLP-1 decelerates gastric emptying and suppresses glucagon secretion. Under physiological conditions, GLP-1 acts as a part of the 'ileal brake', meaning that is slows the transition of nutrients into the distal gut. Animal studies suggest a role for GLP-1 in the development and growth of the endocrine pancreas. In light of its multiple actions throughout the body, different therapeutic applications of GLP-1 are possible. Promising results have been obtained with GLP-1 in the treatment of type 2 diabetes, but its potential to reduce appetite and food intake may also allow its use for the treatment of obesity. While rapid in vivo degradation of GLP-1 has yet prevented its broad clinical use, different pharmacological approaches aiming to extend the in vivo half-life of GLP-1 or to inhibit its inactivation are currently being evaluated. Therefore, antidiabetic treatment based on GLP-1 may become available within the next years. This review will summarize the biological effects of GLP-1, characterize its role in human biology and pathology, and discuss potential clinical applications as well as current clinical studies.
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Affiliation(s)
- Juris J Meier
- Larry L. Hillblom Islet Research Center, UCLA School of Medicine, Los Angeles, USA
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Immunohistochemical and Morphometrical Studies on the Distribution of Glucagon-like Peptide-1 (GLP-1)-immunoreactive Cells in the Chicken Intestine. J Poult Sci 2005. [DOI: 10.2141/jpsa.42.223] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Mortensen K, Christensen LL, Holst JJ, Orskov C. GLP-1 and GIP are colocalized in a subset of endocrine cells in the small intestine. REGULATORY PEPTIDES 2003; 114:189-96. [PMID: 12832109 DOI: 10.1016/s0167-0115(03)00125-3] [Citation(s) in RCA: 241] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The incretin hormones GIP and GLP-1 are thought to be produced in separate endocrine cells located in the proximal and distal ends of the mammalian small intestine, respectively. METHODS AND RESULTS Using double immunohistochemistry and in situ hybridization, we found that GLP-1 was colocalized with either GIP or PYY in endocrine cells of the porcine, rat, and human small intestines, whereas GIP and PYY were rarely colocalized. Thus, of all the cells staining positively for either GLP-1, GIP, or both, 55-75% were GLP-1 and GIP double-stained in the mid-small intestine. Concentrations of extractable GIP and PYY were highest in the midjejunum [154 (95-167) and 141 (67-158) pmol/g, median and range, respectively], whereas GLP-1 concentrations were highest in the ileum [92 (80-207) pmol/l], but GLP-1, GIP, and PYY immunoreactive cells were found throughout the porcine small intestine. CONCLUSIONS Our results provide a morphological basis to suggest simultaneous, rather than sequential, secretion of these hormones by postprandial luminal stimulation.
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Affiliation(s)
- Kristine Mortensen
- Department of Medical Anatomy, The Panum Institute, University of Copenhagen, Blegdamsvej 3 C, Copenhagen DK-2200, Denmark
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Comparative Study on the Distribution of Glucagon-like Peptide-1 (GLP-1)-immunoreactive Cells in the Intestine of Chicken and Ostrich. J Poult Sci 2003. [DOI: 10.2141/jpsa.40.39] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Kieffer TJ, Hussain MA, Habener JF. Glucagon and Glucagon‐like Peptide Production and Degradation. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kawamoto S, Nitta Y, Tashiro F, Nakano A, Yamato E, Tahara H, Tabayashi K, Miyazaki J. Suppression of T(h)1 cell activation and prevention of autoimmune diabetes in NOD mice by local expression of viral IL-10. Int Immunol 2001; 13:685-94. [PMID: 11312256 DOI: 10.1093/intimm/13.5.685] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Insulin-dependent diabetes mellitus in the NOD mouse model is caused by the T cell-mediated autoimmune destruction of pancreatic beta cells. Viral IL-10 (vIL-10), encoded in the Epstein-Barr virus genome, shares many of the anti-inflammatory properties of cellular IL-10, but lacks its immunostimulatory properties. In the present study, we generated transgenic (Tg) NOD mice in which vIL-10 was produced exclusively in pancreatic islets and investigated the effect of vIL-10 on the development of diabetes. The accumulation of lymphocytes around islets was more prominent, but the invasive insulitis decreased in the vIL-10 Tg mice. The incidence of diabetes was markedly reduced in the vIL-10 Tg mice, in clear contrast to the accelerated diabetes seen in the murine IL-10 Tg NOD mice. IL-12p40 and IFN-gamma mRNA levels were decreased in pancreata of the vIL-10 Tg mice, although CD4 mRNA level was markedly increased. These results suggest that locally produced vIL-10 induced leukocyte migration, but inhibited the activation of T(h)1, probably through suppressing the production of IL-12. They indicate that vIL-10 may well be superior to cellular IL-10 in the treatment of autoimmune diabetes. The vIL-10 Tg NOD mice should provide a useful tool for understanding the differential action of vIL-10 versus cellular IL-10.
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Affiliation(s)
- S Kawamoto
- Department of Nutrition and Physiological Chemistry, Osaka University Medical School, Suita, Osaka 565-0871, Japan
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Affiliation(s)
- T J Kieffer
- Department of Medicine, University of Alberta, Edmonton, Canada.
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Merchenthaler I, Lane M, Shughrue P. Distribution of pre-pro-glucagon and glucagon-like peptide-1 receptor messenger RNAs in the rat central nervous system. J Comp Neurol 1999; 403:261-80. [PMID: 9886047 DOI: 10.1002/(sici)1096-9861(19990111)403:2<261::aid-cne8>3.0.co;2-5] [Citation(s) in RCA: 589] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is derived from the peptide precursor pre-pro-glucagon (PPG) by enzymatic cleavage and acts via its receptor, glucagon-like peptide-1 receptor (GLP-1R). By using riboprobes complementary to PPG and GLP-1R, we described the distribution of PPG and GLP-1R messenger RNAs (mRNAs) in the central nervous system of the rat. PPG mRNA-expressing perikarya were restricted to the nucleus of the solitary tact or to the dorsal and ventral medulla and olfactory bulb. GLP-1R mRNA was detected in numerous brain regions, including the mitral cell layer of the olfactory bulb; temporal cortex; caudal hippocampus; lateral septum; amygdala; nucleus accumbens; ventral pallium; nucleus basalis Meynert; bed nucleus of the stria terminalis; preoptic area; paraventricular, supraoptic, arcuate, and dorsomedial nuclei of the hypothalamus; lateral habenula; zona incerta; substantia innominata; posterior thalamic nuclei; ventral tegmental area; dorsal tegmental, posterodorsal tegmental, and interpeduncular nuclei; substantia nigra, central gray; raphe nuclei; parabrachial nuclei; locus ceruleus, nucleus of the solitary tract; area postrema; dorsal nucleus of the vagus; lateral reticular nucleus; and spinal cord. These studies, in addition to describing the sites of GLP-1 and GLP-1R synthesis, suggest that the efferent connections from the nucleus of the solitary tract are more widespread than previously reported. Although the current role of GLP-1 in regulating neuronal physiology is not known, these studies provide detailed information about the sites of GLP-1 synthesis and potential sites of action, an important first step in evaluating the function of GLP-1 in the brain. The widespread distribution of GLP-1R mRNA-containing cells strongly suggests that GLP-1 not only functions as a satiety factor but also acts as a neurotransmitter or neuromodulator in anatomically and functionally distinct areas of the central nervous system.
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Affiliation(s)
- I Merchenthaler
- Womens Health Research Institute, Wyeth-Ayerst Research, Radnor, Pennsylvania 19087, USA.
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Denef C. Autocrine/Paracrine Intermediates in Hormonal Action and Modulation of Cellular Responses to Hormones. Compr Physiol 1998. [DOI: 10.1002/cphy.cp070118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Deacon CF, Johnsen AH, Holst JJ. Human colon produces fully processed glucagon-like peptide-1 (7-36) amide. FEBS Lett 1995; 372:269-72. [PMID: 7556682 DOI: 10.1016/0014-5793(95)00983-g] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The human colon contains many open-type endocrine cells which express the preproglucagon gene and possess glucagon-like peptide-1 (GLP-1) immunoreactivity, but the molecular form of the peptide is unknown. Acid ethanol extracts of human colon (n = 4) were subjected to gel filtration and successive purification by high-pressure liquid chromatography, monitored by specific RIAs. A single GLP-1-immunoreactive peak was isolated and identified as GLP-1 (7-36)amide by amino acid sequence analysis and mass spectrometry. We conclude that proglucagon is processed in the large intestine in the same manner as in the small intestine, and results in the formation of fully processed biologically active GLP-1.
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Affiliation(s)
- C F Deacon
- Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark
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Montaron A, Moyse E, Barré H. Radioautographic demonstration and localization of glucagon receptors in duck brain. Brain Res 1994; 663:121-30. [PMID: 7850460 DOI: 10.1016/0006-8993(94)90469-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The discovery of glucagon biosynthesis and receptors within mammalian brain has led one to suspect a neurotransmitter role for glucagon. In order to address this hypothesis in birds, we investigated the existence of glucagon receptors in duck brain by radioligand binding on fresh tissue sections and radioautography. Specific high-affinity [125I]glucagon binding sites similar to those in the liver were demonstrated in the avian brain. Mapping of these putative glucagon receptors revealed a discrete distributional pattern. Most of the [125I]glucagon binding capacity in duck brain is concentrated within the telencephalon, mainly in components of motor and limbic systems. Specific labeling densities were associated with avian equivalents of the mammalian pyramidal system (hyperstriatum accessorium; archistriatum intermedium and tractus occipitomesencephalicus) and extrapyramidal system (paleostriatum augmentatum, paleostriatum primitivum and lobus parolfactorius), as well as several limbic structures (hippocampal formation, nucleus taeniae and the caudal part of the archistriatum). Few glucagon-reactive foci were detected in the diencephalon (the nucleus dorsomedialis of hypothalamus, the two circumventricular organs, organum vasculosum of the lamina terminalis and median eminence and the nucleus habenularis medialis). These findings suggest that glucagon might be involved in the central control of somatic motricity and basic behaviors and point therefore to glucagon as a new neuroactive messenger in avian brain. The extensive difference between the distribution of glucagon binding sites observed in duck brain and that previously reported in rat brain suggests that glucagon does not subserve the same physiological role(s) in avian and mammalian brains.
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Affiliation(s)
- A Montaron
- Laboratoire de Physiologie Générale et Comparée, Université Claude Bernard-Lyon, Villeurbanne, France
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Abstract
The post-translational processing of proglucagon in the small intestine gives rise to glucagon-like peptide-1 (PG 78-107 amide) which has profound effects on the endocrine pancreas, and in many species also on the stomach. Glucagon-like peptide-1 (PG 78-107 amide) is secreted in man in response to physiological stimuli e.g. a mixed meal. Glucagon-like peptide-1, in concentrations corresponding to those observed in response to meals, strongly stimulates insulin secretion, in all mammals studied, even more potently than the gastric inhibitory peptide. Thus, glucagon-like peptide-1 fulfills the classic criteria for being a hormone and is likely to be a new incretin. The glucagon inhibitory effect of glucagon-like peptide-1 (PG 78-107 amide) probably further potentiates the effect of glucagon-like peptide-1 on glucose metabolism and distinguished this peptide from other intestinal peptides which have been proposed as incretins. Glucagon-like peptide-1 also inhibits gastric acid secretion and gastric emptying in man. The latter delays nutrient entry to the intestine and thereby diminishes meal-induced glucose excursions. Elevated plasma concentrations of immunoreactive glucagon-like peptide-1 have been reported in Type 2 (noninsulin-dependent) diabetic patients, however, the consequences of the elevation are not yet known. However, elevated levels of glucagon-like peptide-1 in patients with increased gastric emptying rate (post-gastrectomy syndromes) may be responsible for the exaggerated insulin secretion seen in these patients.
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Affiliation(s)
- C Orskov
- Department of Clinical Chemistry, Rigshospitalet, University of Copenhagen, Denmark
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Eissele R, Göke R, Willemer S, Harthus HP, Vermeer H, Arnold R, Göke B. Glucagon-like peptide-1 cells in the gastrointestinal tract and pancreas of rat, pig and man. Eur J Clin Invest 1992; 22:283-91. [PMID: 1499644 DOI: 10.1111/j.1365-2362.1992.tb01464.x] [Citation(s) in RCA: 437] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A highly specific monoclonal antibody directed against the C-terminal part of glucagon-like peptide-1 (GLP-1) was raised to immunohistochemically evaluate the distribution of GLP-1 containing cells in the entire gastrointestinal tract including pancreas of rat, pig and man. In the pancreas GLP-1-immunoreactive cells were found variously shaped and predominantly located in the periphery of the islets. Ultrastructurally, GLP-1 was co-localized with glucagon in the alpha-granula of A-cells and was mainly restricted to the electrondense core. In the intestine open type cells reaching the lumen via a slender apical process were stained with the GLP-1 antibody. They occurred in all parts of the crypts but predominantly in the basal portion. The density of GLP-1 immunoreactive cells varied between species in a characteristic order: rat greater than pig greater than man. In pig and human gut a large number of cells occurred in the distal jejunum and ileum. A continuous increase of cell densities was found from the proximal to the distal colon resulting in highest numbers in the rectum. In rats the highest cell density occurred in the ileum. Again, a continuous increase of GLP-1-positive cell numbers was evident from the proximal to the distal portion of small and large bowel. GLP-1 was partly co-localized with PYY. The GLP-1 positive cells appeared electronmicroscopically as L-cells with the typical large granula. This morphological data indicates that GLP-1-releasing cells in the small intestine are appropriately positioned in the distal part to sense and respond to the presence of nutrients that have escaped the absorptive surface of the upper small intestine.
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Affiliation(s)
- R Eissele
- Department of Internal Medicine, Philipps University of Marburg, Germany
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Uttenthal LO, Toledano A, Blázquez E. Autoradiographic localization of receptors for glucagon-like peptide-1 (7-36) amide in rat brain. Neuropeptides 1992; 21:143-6. [PMID: 1352862 DOI: 10.1016/0143-4179(92)90036-v] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) has a sparse but well defined distribution in the rat brain where it is co-localized with glucagon-like immunoreactivity due to other fragments of the glucagon precursor. We have investigated the localization of GLP-1 receptors in rat brain using mono-125I-iodinated GLP-1(7-36) amide, the biologically active form of the peptide that occurs in brain, as the tracer for binding and autoradiographic studies of tissue sections. Displaceable binding of the label was sharply localized to discrete areas, being high in mamillary nuclei, the arcuate nucleus, nucleus of the solitary tract and the pretectal area, intermediate in the lateral septal nuclei, olfactory bulb, dorsal tegmental nuclei and the interpenduncular nucleus, and low in other regions. These results indicate areas where GLP-1(7-36) amide may have a role as a neurotransmitter or neuromodulator.
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Affiliation(s)
- L O Uttenthal
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Universidad Complutense, Madrid, Spain
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Affiliation(s)
- R Göke
- Department of Internal Medicine, Philipps University of Marburg, Germany
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Richter G, Göke R, Göke B, Arnold R. Characterization of receptors for glucagon-like peptide-1(7-36)amide on rat lung membranes. FEBS Lett 1990; 267:78-80. [PMID: 2163902 DOI: 10.1016/0014-5793(90)80292-q] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Specific binding of 125I-labelled GLP-1(7-36)amide to rat lung membranes was dependent upon time and temperature and was proportional to membrane protein concentration. Binding was inhibited in a concentration-dependent manner by unlabelled GLP-1(7-36)amide consistent with the presence of a single class of binding sites with a dissociation constant (Kd) of 1.67 +/- 0.29 nmol/l. GLP-1(1-36)amide was 260 times less potent in inhibiting the binding of 125I-labelled GLP-1(7-36)amide to lung membranes (Kd of 448 +/- 93 nmol/l). Vasoactive intestinal polypeptide and peptide-histidine-isoleucine also displaced 125I-labelled GLP-1(7-36)amide from the receptor concentration-dependently; the Kd was 4.31 +/- 0.8 and 7.93 +/- 4.79 nmol/l, respectively. Guanine nucleotides (GTP-gamma-S, GDP-beta-S) decreased the binding of 125I-labelled GLP-1(7-36)amide to rat lung membranes as was found for GLP-1(7-36)amide receptors in RINm5F cells which were also shown to be coupled to the adenylate cyclase system.
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Affiliation(s)
- G Richter
- Department of Internal Medicine, Philipps-University of Marburg, FRG
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Hirota M, Hashimoto M, Hiratsuka M, Ohboshi C, Yoshimoto S, Yano M, Mizuno A, Shima K. Alterations of plasma immunoreactive glucagon-like peptide-1 behavior in non-insulin-dependent diabetics. Diabetes Res Clin Pract 1990; 9:179-85. [PMID: 2376237 DOI: 10.1016/0168-8227(90)90110-f] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The basal level of plasma immunoreactive glucagon-like peptide-1 (IR GLP-1) was significantly elevated in non-insulin-dependent diabetics (NIDD), and this elevation of IR GLP-1 was mainly due to an increase in the large component of IR GLP-1, corresponding to the pancreatic form. During the oral glucose-tolerance test (OGTT), the total plasma IR GLP-1 decreased in normal subjects but increased significantly in diabetic patients. Chromatographic analysis showed that IR GLP-1 consisted of several different molecular forms. OGTT caused a decrease in the pancreatic form but increased the intestinal form in normal subject, resulting into a net decrease in total plasma IR GLP-1. Whereas in NIDD the increase in the intestinal form was more prominent and the suppression of the pancreatic form was practically abolished to result in a net increase of total plasma IR GLP-1. This observation is consistent with the fact that in normal subjects the total change in IR GLP-1 was significantly correlated with both the total change of gut glucagon as well as that of pancreatic glucagon, but in diabetics the total change of GLP-1 only correlated to that of gut glucagon. The impaired suppression of pancreatic GLP-1 and enhanced release of intestinal GLP-1 could have some physiological importance in NIDD.
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Affiliation(s)
- M Hirota
- Department of Laboratory Medicine, School of Medicine, University of Tokushima, Japan
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Scopsi L, Arias J, Houen G, Racchetti G, Fossati GL, Galante YM. Monoclonal antibodies against calcitonin. Characterization and application in light and electron microscopy immunocytochemistry. HISTOCHEMISTRY 1988; 88:113-25. [PMID: 3346173 DOI: 10.1007/bf00493293] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Twenty-seven monoclonal antibodies (MAbs) to synthetic human calcitonin (CT) were characterized for their reactivities with human CT peptide fragments by dot-blot analysis on nitrocellulose paper. Most of the antibodies bound to the C-terminus and fewer to the mid-region of CT. We have studied thyroid tissue specimens from several animal species after fixation in paraformaldehyde-, glutaraldehyde- or picric acid-containing mixtures and cryostat sectioning or embedment in paraffin or plastic (Epon 812 or Lowicryl 4KM) using this panel of MAbs. The site of antigen-antibody reaction was revealed either by immunoperoxidase, immunoalkaline phosphatase or by silver-enhanced immunogold staining methods. All MAbs were able to localize CT in human, rat and mouse thyroid C cells. Nineteen MAbs recognizing synthetic salmon CT and synthetic [Asu1,7]-eel CT by dot-blot, reacted with chicken ultimobranchial body C cells. One MAb recognizing native porcine CT by dot-blot, stained C cells in hog thyroid. Immunopositivity was confined to the cytoplasm and ultrastructural immunogold labelling demonstrated that cytoplasmic secretory granules were stained. Surgical specimens from human medullary thyroid carcinoma were also analysed for the presence of CT and a variable number of positive cells was found. Furthermore, Congo red-positive areas were shown to react with the MAbs. All conventional staining and immunoabsorption controls were negative. Hence, these MAbs may be suitable for use in routine immunopathological diagnosis of CT-producing tumors and for immunocytochemical localization of the three major CT variants in different animal species.
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Affiliation(s)
- L Scopsi
- Unit of Histochemistry, University Institute of Pathological Anatomy, Copenhagen, Denmark
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