1
|
Lowe NM, Hall AG, Broadley MR, Foley J, Boy E, Bhutta ZA. Preventing and Controlling Zinc Deficiency Across the Life Course: A Call to Action. Adv Nutr 2024; 15:100181. [PMID: 38280724 PMCID: PMC10882121 DOI: 10.1016/j.advnut.2024.100181] [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] [Received: 10/31/2023] [Revised: 01/11/2024] [Accepted: 01/23/2024] [Indexed: 01/29/2024] Open
Abstract
Through diverse roles, zinc determines a greater number of critical life functions than any other single micronutrient. Beyond the well-recognized importance of zinc for child growth and resistance to infections, zinc has numerous specific roles covering the regulation of glucose metabolism, and growing evidence links zinc deficiency with increased risk of diabetes and cardiometabolic disorders. Zinc nutriture is, thus, vitally important to health across the life course. Zinc deficiency is also one of the most common forms of micronutrient malnutrition globally. A clearer estimate of the burden of health disparity attributable to zinc deficiency in adulthood and later life emerges when accounting for its contribution to global elevated fasting blood glucose and related noncommunicable diseases (NCDs). Yet progress attenuating its prevalence has been limited due, in part, to the lack of sensitive and specific methods to assess human zinc status. This narrative review covers recent developments in our understanding of zinc's role in health, the impact of the changing climate and global context on zinc intake, novel functional biomarkers showing promise for monitoring population-level interventions, and solutions for improving population zinc intake. It aims to spur on implementation of evidence-based interventions for preventing and controlling zinc deficiency across the life course. Increasing zinc intake and combating global zinc deficiency requires context-specific strategies and a combination of complementary, evidence-based interventions, including supplementation, food fortification, and food and agricultural solutions such as biofortification, alongside efforts to improve zinc bioavailability. Enhancing dietary zinc content and bioavailability through zinc biofortification is an inclusive nutrition solution that can benefit the most vulnerable individuals and populations affected by inadequate diets to the greatest extent.
Collapse
Affiliation(s)
- Nicola M Lowe
- Center for Global Development, University of Central Lancashire, Preston, United Kingdom.
| | - Andrew G Hall
- Department of Nutrition, University of California, Davis, CA, United States; Department of Nutritional Sciences & Toxicology, University of California, Berkeley, CA, United States
| | - Martin R Broadley
- Rothamsted Research, West Common, Harpenden, United Kingdom; School of Biosciences, University of Nottingham, Loughborough, United Kingdom
| | - Jennifer Foley
- HarvestPlus, International Food Policy Research Institute, Washington, DC, United States
| | - Erick Boy
- HarvestPlus, International Food Policy Research Institute, Washington, DC, United States
| | - Zulfiqar A Bhutta
- Center for Global Child Health, The Hospital for Sick Children, Toronto, ON, Canada; Center of Excellence in Women and Child Health, Aga Khan University, Karachi, Pakistan
| |
Collapse
|
2
|
Hölzen L, Schultes B, Meyhöfer SM, Meyhöfer S. Hypoglycemia Unawareness-A Review on Pathophysiology and Clinical Implications. Biomedicines 2024; 12:391. [PMID: 38397994 PMCID: PMC10887081 DOI: 10.3390/biomedicines12020391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 01/31/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Hypoglycemia is a particular problem in people with diabetes while it can also occur in other clinical circumstances. Hypoglycemia unawareness describes a condition in which autonomic and neuroglycopenic symptoms of hypoglycemia decrease and hence are hardly perceivable. A failure to recognize hypoglycemia in time can lead to unconsciousness, seizure, and even death. The risk factors include intensive glycemic control, prior episodes of severe hypoglycemia, long duration of diabetes, alcohol consumption, exercise, renal failure, and sepsis. The pathophysiological mechanisms are manifold, but mainly concern altered brain glucose sensing, cerebral adaptations, and an impaired hormonal counterregulation with an attenuated release of glucagon, epinephrine, growth hormone, and other hormones, as well as impaired autonomous and neuroglycopenic symptoms. Physiologically, this counterregulatory response causes blood glucose levels to rise. The impaired hormonal counterregulatory response to recurrent hypoglycemia can lead to a vicious cycle of frequent and poorly recognized hypoglycemic episodes. There is a shift in glycemic threshold to trigger hormonal counterregulation, resulting in hypoglycemia-associated autonomic failure and leading to the clinical syndrome of hypoglycemia unawareness. This clinical syndrome represents a particularly great challenge in diabetes treatment and, thus, prevention of hypoglycemia is crucial in diabetes management. This mini-review provides an overview of hypoglycemia and the associated severe complication of impaired hypoglycemia awareness and its symptoms, pathophysiology, risk factors, consequences, as well as therapeutic strategies.
Collapse
Affiliation(s)
- Laura Hölzen
- Institute for Endocrinology & Diabetes, University of Lübeck, 23562 Lübeck, Germany; (L.H.); (B.S.)
- Department of Internal Medicine 1, Endocrinology & Diabetes, University of Lübeck, 23562 Lübeck, Germany
| | - Bernd Schultes
- Institute for Endocrinology & Diabetes, University of Lübeck, 23562 Lübeck, Germany; (L.H.); (B.S.)
- Metabolic Center St. Gallen, friendlyDocs Ltd., 9016 St. Gallen, Switzerland
| | - Sebastian M. Meyhöfer
- Institute for Endocrinology & Diabetes, University of Lübeck, 23562 Lübeck, Germany; (L.H.); (B.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany
| | - Svenja Meyhöfer
- Institute for Endocrinology & Diabetes, University of Lübeck, 23562 Lübeck, Germany; (L.H.); (B.S.)
- Department of Internal Medicine 1, Endocrinology & Diabetes, University of Lübeck, 23562 Lübeck, Germany
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany
| |
Collapse
|
3
|
Campbell JE, Müller TD, Finan B, DiMarchi RD, Tschöp MH, D'Alessio DA. GIPR/GLP-1R dual agonist therapies for diabetes and weight loss-chemistry, physiology, and clinical applications. Cell Metab 2023; 35:1519-1529. [PMID: 37591245 PMCID: PMC10528201 DOI: 10.1016/j.cmet.2023.07.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/09/2023] [Accepted: 07/21/2023] [Indexed: 08/19/2023]
Abstract
The incretin system is an essential metabolic axis that regulates postprandial metabolism. The two incretin peptides that enable this effect are the glucose-dependent insulinotropic polypeptide (GIP) and the glucagon-like peptide 1 (GLP-1), which have cognate receptors (GIPR and GLP-1R) on islet β cells as well as in other tissues. Pharmacologic engagement of the GLP-1R is a proven strategy for treating hyperglycemia in diabetes and reducing body weight. Tirzepatide is the first monomeric peptide with dual activity at both incretin receptors now available for clinical use, and in clinical trials it has shown unprecedented effects to reduce blood glucose and body weight. Here, we discuss the foundational science that led to the development of monomeric multi-incretin receptor agonists, culminating in the development of tirzepatide. We also look to the future of this field and comment on how the concept of multi-receptor agonists will continue to progress for the treatment of metabolic disease.
Collapse
Affiliation(s)
- Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University, Durham, NC, USA; Department of Medicine, Division of Endocrinology, Duke University, Durham, NC, USA; Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA.
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Brian Finan
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA
| | | | - Matthias H Tschöp
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Division of Metabolic Diseases, Department of Medicine, Technical University of München, Munich, Germany; Helmholtz Munich, Neuherberg, Germany.
| | - David A D'Alessio
- Duke Molecular Physiology Institute, Duke University, Durham, NC, USA; Department of Medicine, Division of Endocrinology, Duke University, Durham, NC, USA
| |
Collapse
|
4
|
Chen W, Cui W, Wu J, Zheng W, Sun X, Zhang J, Shang H, Yuan Y, Li X, Wang J, Hu X, Chen L, Zeng F, Xiao RP, Zhang X. Blocking IL-6 signaling improves glucose tolerance via SLC39A5-mediated suppression of glucagon secretion. Metabolism 2023:155641. [PMID: 37380017 DOI: 10.1016/j.metabol.2023.155641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/19/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023]
Abstract
BACKGROUND AND AIMS Hyperinsulinemia, hyperglucagonemia, and low-grade inflammation are frequently presented in obesity and type 2 diabetes (T2D). The pathogenic regulation between hyperinsulinemia/insulin resistance (IR) and low-grade inflammation is well documented in the development of diabetes. However, the cross-talk of hyperglucagonemia with low-grade inflammation during diabetes progression is poorly understood. In this study, we investigated the regulatory role of proinflammatory cytokine interleukin-6 (IL-6) on glucagon secretion. METHODS The correlations between inflammatory cytokines and glucagon or insulin were analyzed in rhesus monkeys and humans. IL-6 signaling was blocked by IL-6 receptor-neutralizing antibody tocilizumab in obese or T2D rhesus monkeys, glucose tolerance was evaluated by intravenous glucose tolerance test (IVGTT). Glucagon and insulin secretion were measured in isolated islets from wild-type mouse, primary pancreatic α-cells and non-α-cells sorted from GluCre-ROSA26EYFP (GYY) mice, in which the enhanced yellow fluorescent protein (EYFP) was expressed under the proglucagon promoter, by fluorescence-activated cell sorting (FACS). Particularly, glucagon secretion in α-TC1 cells treated with IL-6 was measured, and RNA sequencing was used to screen the mediator underlying IL-6-induced glucagon secretion. SLC39A5 was knocking-down or overexpressed in α-TC1 cells to determine its impact in glucagon secretion and cytosolic zinc density. Dual luciferase and chromatin Immunoprecipitation were applied to analyze the signal transducer and activator of transcription 3 (STAT3) in the regulation of SLC39A5 transcription. RESULTS Plasma IL-6 correlate positively with plasma glucagon levels, but not insulin, in rhesus monkeys and humans. Tocilizumab treatment reduced plasma glucagon, blood glucose and HbA1c in spontaneously obese or T2D rhesus monkeys. Tocilizumab treatment also decreased glucagon levels during IVGTT, and improved glucose tolerance. Moreover, IL-6 significantly increased glucagon secretion in isolated islets, primary pancreatic α-cells and α-TC1 cells. Mechanistically, we found that IL-6-activated STAT3 downregulated the zinc transporter SLC39A5, which in turn reduced cytosolic zinc concentration and ATP-sensitive potassium channel activity and augmented glucagon secretion. CONCLUSIONS This study demonstrates that IL-6 increases glucagon secretion via the downregulation of zinc transporter SLC39A5. This result revealed the molecular mechanism underlying the pathogenesis of hyperglucagonemia and a previously unidentified function of IL-6 in the pathophysiology of T2D, providing a potential new therapeutic strategy of targeting IL-6/glucagon to preventing or treating T2D.
Collapse
Affiliation(s)
- Wenli Chen
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Weiyi Cui
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Jianhong Wu
- Department of Rheumatology and Immunology, Dazhou Central Hospital, Dazhou, China
| | - Wen Zheng
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Xueting Sun
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Jie Zhang
- Department of Clinical Research Center, Dazhou Central Hospital, Dazhou 635000, China
| | - Haibao Shang
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Ye Yuan
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Xue Li
- Department of Clinical Research Center, Dazhou Central Hospital, Dazhou 635000, China
| | - Jue Wang
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Xinli Hu
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Liangyi Chen
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China; National Biomedical Imaging Center, School of Future Technology, Peking University, Beijing, China; State Key Laboratory of Biomembrane and Membrane Biotechnology, Peking-Tsinghua Center for Life Sciences, Beijing 100871, China
| | - Fanxin Zeng
- Department of Clinical Research Center, Dazhou Central Hospital, Dazhou 635000, China.
| | - Rui-Ping Xiao
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China; State Key Laboratory of Biomembrane and Membrane Biotechnology, Peking-Tsinghua Center for Life Sciences, Beijing 100871, China.
| | - Xiuqin Zhang
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China; National Biomedical Imaging Center, School of Future Technology, Peking University, Beijing, China.
| |
Collapse
|
5
|
Capozzi ME, D'Alessio DA, Campbell JE. The past, present, and future physiology and pharmacology of glucagon. Cell Metab 2022; 34:1654-1674. [PMID: 36323234 PMCID: PMC9641554 DOI: 10.1016/j.cmet.2022.10.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/23/2022] [Accepted: 09/30/2022] [Indexed: 11/07/2022]
Abstract
The evolution of glucagon has seen the transition from an impurity in the preparation of insulin to the development of glucagon receptor agonists for use in type 1 diabetes. In type 2 diabetes, glucagon receptor antagonists have been explored to reduce glycemia thought to be induced by hyperglucagonemia. However, the catabolic actions of glucagon are currently being leveraged to target the rise in obesity that paralleled that of diabetes, bringing the pharmacology of glucagon full circle. During this evolution, the physiological importance of glucagon advanced beyond the control of hepatic glucose production, incorporating critical roles for glucagon to regulate both lipid and amino acid metabolism. Thus, it is unsurprising that the study of glucagon has left several paradoxes that make it difficult to distill this hormone down to a simplified action. Here, we describe the history of glucagon from the past to the present and suggest some direction to the future of this field.
Collapse
Affiliation(s)
- Megan E Capozzi
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA
| | - David A D'Alessio
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA; Department of Medicine, Endocrinology Division, Duke University Medical Center, Durham, NC 27701, USA
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA; Department of Medicine, Endocrinology Division, Duke University Medical Center, Durham, NC 27701, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27701, USA.
| |
Collapse
|
6
|
Habegger KM. Cross Talk Between Insulin and Glucagon Receptor Signaling in the Hepatocyte. Diabetes 2022; 71:1842-1851. [PMID: 35657690 PMCID: PMC9450567 DOI: 10.2337/dbi22-0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/19/2022] [Indexed: 11/13/2022]
Abstract
While the consumption of external energy (i.e., feeding) is essential to life, this action induces a temporary disturbance of homeostasis in an animal. A primary example of this effect is found in the regulation of glycemia. In the fasted state, stored energy is released to maintain physiological glycemic levels. Liver glycogen is liberated to glucose, glycerol and (glucogenic) amino acids are used to build new glucose molecules (i.e., gluconeogenesis), and fatty acids are oxidized to fuel long-term energetic demands. This regulation is driven primarily by the counterregulatory hormones epinephrine, growth hormone, cortisol, and glucagon. Conversely, feeding induces a rapid influx of diverse nutrients, including glucose, that disrupt homeostasis. Consistently, a host of hormonal and neural systems under the coordination of insulin are engaged in the transition from fasting to prandial states to reduce this disruption. The ultimate action of these systems is to appropriately store the newly acquired energy and to return to the homeostatic norm. Thus, at first glance it is tempting to assume that glucagon is solely antagonistic regarding the anabolic effects of insulin. We have been intrigued by the role of glucagon in the prandial transition and have attempted to delineate its role as beneficial or inhibitory to glycemic control. The following review highlights this long-known yet poorly understood hormone.
Collapse
Affiliation(s)
- Kirk M. Habegger
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| |
Collapse
|
7
|
Story LH, Wilson LM. New Developments in Glucagon Treatment for Hypoglycemia. Drugs 2022; 82:1179-1191. [PMID: 35932416 DOI: 10.1007/s40265-022-01754-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2022] [Indexed: 11/28/2022]
Abstract
Glucagon is essential for endogenous glucose regulation along with the paired hormone, insulin. Unlike insulin, pharmaceutical use of glucagon has been limited due to the unstable nature of the peptide. Glucagon has the potential to address hypoglycemia as a major limiting factor in the treatment of diabetes, which remains very common in the type 1 and type 2 diabetes. Recent developments are poised to change this paradigm and expand the use of glucagon for people with diabetes. Glucagon emergency kits have major limitations for their use in treating severe hypoglycemia. A complicated reconstitution and injection process often results in incomplete or aborted administration. New preparations include intranasal glucagon with an easy-to-use and needle-free nasal applicator as well as two stable liquid formulations in pre-filled injection devices. These may ease the burden of severe hypoglycemia treatment. The liquid preparations may also have a role in the treatment of non-severe hypoglycemia. Despite potential benefits of expanded use of glucagon, undesirable side effects (nausea, vomiting), cost, and complexity of adding another medication may limit real-world use. Additionally, more long-term safety and outcome data are needed before widespread, frequent use of glucagon is recommended by providers.
Collapse
Affiliation(s)
- LesleAnn Hayward Story
- Division of Endocrinology, Harold Schnitzer Diabetes Health Center, Oregon Health & Science University, Portland, OR, USA
| | - Leah M Wilson
- Division of Endocrinology, Harold Schnitzer Diabetes Health Center, Oregon Health & Science University, Portland, OR, USA.
| |
Collapse
|
8
|
Germanos M, Gao A, Taper M, Yau B, Kebede MA. Inside the Insulin Secretory Granule. Metabolites 2021; 11:metabo11080515. [PMID: 34436456 PMCID: PMC8401130 DOI: 10.3390/metabo11080515] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 12/19/2022] Open
Abstract
The pancreatic β-cell is purpose-built for the production and secretion of insulin, the only hormone that can remove glucose from the bloodstream. Insulin is kept inside miniature membrane-bound storage compartments known as secretory granules (SGs), and these specialized organelles can readily fuse with the plasma membrane upon cellular stimulation to release insulin. Insulin is synthesized in the endoplasmic reticulum (ER) as a biologically inactive precursor, proinsulin, along with several other proteins that will also become members of the insulin SG. Their coordinated synthesis enables synchronized transit through the ER and Golgi apparatus for congregation at the trans-Golgi network, the initiating site of SG biogenesis. Here, proinsulin and its constituents enter the SG where conditions are optimized for proinsulin processing into insulin and subsequent insulin storage. A healthy β-cell is continually generating SGs to supply insulin in vast excess to what is secreted. Conversely, in type 2 diabetes (T2D), the inability of failing β-cells to secrete may be due to the limited biosynthesis of new insulin. Factors that drive the formation and maturation of SGs and thus the production of insulin are therefore critical for systemic glucose control. Here, we detail the formative hours of the insulin SG from the luminal perspective. We do this by mapping the journey of individual members of the SG as they contribute to its genesis.
Collapse
|
9
|
Ng XW, Chung YH, Piston DW. Intercellular Communication in the Islet of Langerhans in Health and Disease. Compr Physiol 2021; 11:2191-2225. [PMID: 34190340 PMCID: PMC8985231 DOI: 10.1002/cphy.c200026] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Blood glucose homeostasis requires proper function of pancreatic islets, which secrete insulin, glucagon, and somatostatin from the β-, α-, and δ-cells, respectively. Each islet cell type is equipped with intrinsic mechanisms for glucose sensing and secretory actions, but these intrinsic mechanisms alone cannot explain the observed secretory profiles from intact islets. Regulation of secretion involves interconnected mechanisms among and between islet cell types. Islet cells lose their normal functional signatures and secretory behaviors upon dispersal as compared to intact islets and in vivo. In dispersed islet cells, the glucose response of insulin secretion is attenuated from that seen from whole islets, coordinated oscillations in membrane potential and intracellular Ca2+ activity, as well as the two-phase insulin secretion profile, are missing, and glucagon secretion displays higher basal secretion profile and a reverse glucose-dependent response from that of intact islets. These observations highlight the critical roles of intercellular communication within the pancreatic islet, and how these communication pathways are crucial for proper hormonal and nonhormonal secretion and glucose homeostasis. Further, misregulated secretions of islet secretory products that arise from defective intercellular islet communication are implicated in diabetes. Intercellular communication within the islet environment comprises multiple mechanisms, including electrical synapses from gap junctional coupling, paracrine interactions among neighboring cells, and direct cell-to-cell contacts in the form of juxtacrine signaling. In this article, we describe the various mechanisms that contribute to proper islet function for each islet cell type and how intercellular islet communications are coordinated among the same and different islet cell types. © 2021 American Physiological Society. Compr Physiol 11:2191-2225, 2021.
Collapse
Affiliation(s)
- Xue W Ng
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - Yong H Chung
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| |
Collapse
|
10
|
Zhu X, Lin C, Li L, Hu S, Cai X, Ji L. SGLT2i increased the plasma fasting glucagon level in patients with diabetes: A meta-analysis. Eur J Pharmacol 2021; 903:174145. [PMID: 33957085 DOI: 10.1016/j.ejphar.2021.174145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 04/11/2021] [Accepted: 04/28/2021] [Indexed: 02/06/2023]
Abstract
Increased glucagon level was hypothesized to participate in the ketoacidosis associated with sodium-glucose co-transporter 2 inhibitors (SGLT2i) treatment. However, the effect of SGLT2i on glucagon remains controversial. Hence, we conducted this meta-analysis to assess the overall effect of SGLT2i treatment on plasma fasting glucagon level in patients with diabetes. PubMed/MEDLINE, Embase, and Cochrane databases were searched for studies published before August 2020. Clinical trials in patients with type 1 diabetes mellitus and type 2 diabetes mellitus with reports of glucagon changes before and after SGLT2i intervention were included. Eligible trials were analyzed by fixed-effect model, random effect model, and meta-regression analysis accordingly. In total, ten trials were included in this meta-analysis. Compared with the non-SGLT2i treatment group, SGLT2i treatment resulted in increased plasma fasting glucagon levels with significance (WMD, 8.35 pg/ml; 95% CI, 2.17-14.54 pg/ml, P<0.01) in patients with diabetes mellitus. Besides, when compared with non-SGLT2i control group, the insulin level decreased (WMD, -2.78 μU/ml; 95% CI, -5.11 to -0.46 μU/ml, P = 0.02) and ketone body level increased (WMD, 0.17 mmol/l; 95% CI, 0.09-0.25 mmol/l, P<0.01) in patients with type 2 diabetes. In conclusion, our result indicated SGLT2i intervention would increase the plasma fasting glucagon level in patients with diabetes mellitus. The increase in plasma fasting glucagon level may be associated with reduced insulin level. The increased glucagon-insulin ratio after the use of SGLT2i may make diabetic patients susceptible to ketosis.
Collapse
Affiliation(s)
- Xingyun Zhu
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Chu Lin
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Li Li
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Suiyuan Hu
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Xiaoling Cai
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Linong Ji
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| |
Collapse
|
11
|
Tanday N, Flatt PR, Irwin N. Metabolic responses and benefits of glucagon-like peptide-1 (GLP-1) receptor ligands. Br J Pharmacol 2021; 179:526-541. [PMID: 33822370 PMCID: PMC8820187 DOI: 10.1111/bph.15485] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 12/19/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone that has undergone a revolutionary turnaround from discovery to clinically approved therapeutic. Rapid progress in drug design and formulation has led from initial development of short- and long-acting drugs suitable for daily or weekly parenteral administration, respectively, through to the most recent approval of an orally active GLP-1 agent. The current review outlines the biological action profile of GLP-1 including the various beneficial metabolic responses in pancreatic and extra-pancreatic tissues, including the gastrointestinal tract, liver, bone and kidney as well as the reproductive cardiovascular and CNS. We then briefly consider clinically approved GLP-1 receptor ligands and recent advances in this field. Given the sustained evolution in the area of GLP-1 drug development and excellent safety profile, as well as the plethora of metabolic benefits, clinical approval for use in diseases beyond diabetes and obesity is very much conceivable.
Collapse
Affiliation(s)
- Neil Tanday
- Diabetes Research Group, Ulster University, Coleraine, UK
| | - Peter R Flatt
- Diabetes Research Group, Ulster University, Coleraine, UK
| | - Nigel Irwin
- Diabetes Research Group, Ulster University, Coleraine, UK
| |
Collapse
|
12
|
Guo K, Tian Q, Yang L, Zhou Z. The Role of Glucagon in Glycemic Variability in Type 1 Diabetes: A Narrative Review. Diabetes Metab Syndr Obes 2021; 14:4865-4873. [PMID: 34992395 PMCID: PMC8710064 DOI: 10.2147/dmso.s343514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 12/01/2021] [Indexed: 01/20/2023] Open
Abstract
Type 1 diabetes mellitus (T1DM) is a progressive disease as a result of the severe destruction of islet β-cell function, which leads to high glucose variability in patients. However, α-cell function is also compromised in patients with T1DM, characterized by aberrant fasting and postprandial glucagon secretion. According to recent studies, this aberrant glucagon secretion plays an increasing role in hyperglycemia, insulin-induced hypoglycemia and exercise-associated hypoglycemia in patients with T1DM. With application of continuous glucose monitoring system, dozens of metrics enable the assessment of glycemic variability, which is an integral component of glycemic control for patients with T1DM. There is growing evidences to illustrate the contribution of glucagon secretion to the glycemic variability in patients with T1DM, which may promote the development of new treatment strategies aiming to mitigate glycemic variability associated with aberrant glucagon secretion.
Collapse
Affiliation(s)
- Keyu Guo
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha, 410011, Hunan, People’s Republic of China
| | - Qi Tian
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha, 410011, Hunan, People’s Republic of China
| | - Lin Yang
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha, 410011, Hunan, People’s Republic of China
- Correspondence: Lin Yang; Zhiguang Zhou Email ;
| | - Zhiguang Zhou
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha, 410011, Hunan, People’s Republic of China
| |
Collapse
|
13
|
Früh E, Elgert C, Eggert F, Scherneck S, Rustenbeck I. Glucagonotropic and Glucagonostatic Effects of KATP Channel Closure and Potassium Depolarization. Endocrinology 2021; 162:5892293. [PMID: 32790843 DOI: 10.1210/endocr/bqaa136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 08/05/2020] [Indexed: 02/08/2023]
Abstract
The role of depolarization in the inverse glucose-dependence of glucagon secretion was investigated by comparing the effects of KATP channel block and of high potassium. The secretion of glucagon and insulin by perifused mouse islets was simultaneously measured. Lowering glucose raised glucagon secretion before it decreased insulin secretion, suggesting an alpha cell-intrinsic signal recognition. Raising glucose affected glucagon and insulin secretion at the same time. However, depolarization by tolbutamide, gliclazide, or 15 mM KCl increased insulin secretion before the glucagon secretion receded. In contrast to the robust depolarizing effect of arginine and KCl (15 and 40 mM) on single alpha cells, tolbutamide was of variable efficacy. Only when applied before other depolarizing agents had tolbutamide a consistent depolarizing effect and regularly increased the cytosolic Ca2+ concentration. When tested on inside-out patches tolbutamide was as effective on alpha cells as on beta cells. In the presence of 1 µM clonidine, to separate insulinotropic from glucagonotropic effects, both 500 µM tolbutamide and 30 µM gliclazide increased glucagon secretion significantly, but transiently. The additional presence of 15 or 40 mM KCl in contrast led to a marked and lasting increase of the glucagon secretion. The glucagon secretion by SUR1 knockout islets was not increased by tolbutamide, whereas 40 mM KCl was of unchanged efficiency. In conclusion a strong and sustained depolarization is compatible with a marked and lasting glucagon secretion. KATP channel closure in alpha cells is less readily achieved than in beta cells, which may explain the moderate and transient glucagonotropic effect.
Collapse
Affiliation(s)
- Eike Früh
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Braunschweig, Germany
| | - Christin Elgert
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Braunschweig, Germany
| | - Frank Eggert
- Institute of Psychology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Stephan Scherneck
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Braunschweig, Germany
| | - Ingo Rustenbeck
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Braunschweig, Germany
| |
Collapse
|
14
|
Neumaier F, Schneider T, Albanna W. Ca v2.3 channel function and Zn 2+-induced modulation: potential mechanisms and (patho)physiological relevance. Channels (Austin) 2020; 14:362-379. [PMID: 33079629 PMCID: PMC7583514 DOI: 10.1080/19336950.2020.1829842] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Voltage-gated calcium channels (VGCCs) are critical for Ca2+ influx into all types of excitable cells, but their exact function is still poorly understood. Recent reconstruction of homology models for all human VGCCs at atomic resolution provides the opportunity for a structure-based discussion of VGCC function and novel insights into the mechanisms underlying Ca2+ selective flux through these channels. In the present review, we use these data as a basis to examine the structure, function, and Zn2+-induced modulation of Cav2.3 VGCCs, which mediate native R-type currents and belong to the most enigmatic members of the family. Their unique sensitivity to Zn2+ and the existence of multiple mechanisms of Zn2+ action strongly argue for a role of these channels in the modulatory action of endogenous loosely bound Zn2+, pools of which have been detected in a number of neuronal, endocrine, and reproductive tissues. Following a description of the different mechanisms by which Zn2+ has been shown or is thought to alter the function of these channels, we discuss their potential (patho)physiological relevance, taking into account what is known about the magnitude and function of extracellular Zn2+ signals in different tissues. While still far from complete, the picture that emerges is one where Cav2.3 channel expression parallels the occurrence of loosely bound Zn2+ pools in different tissues and where these channels may serve to translate physiological Zn2+ signals into changes of electrical activity and/or intracellular Ca2+ levels.
Collapse
Affiliation(s)
- Felix Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5) , Jülich, Germany.,University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute of Radiochemistry and Experimental Molecular Imaging , Cologne, Germany
| | - Toni Schneider
- Institute of Neurophysiology , Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Walid Albanna
- Department of Neurosurgery, RWTH Aachen University , Aachen, Germany
| |
Collapse
|
15
|
Loviscach L, Backes TM, Langfermann DS, Ulrich M, Thiel G. Zn 2+ ions inhibit gene transcription following stimulation of the Ca 2+ channels Ca v1.2 and TRPM3. Metallomics 2020; 12:1735-1747. [PMID: 33030499 DOI: 10.1039/d0mt00180e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Zinc, a trace element, is necessary for the correct structure and function of many proteins. Therefore, Zn2+ has to be taken up by the cells, using specific Zn2+ transporters or Ca2+ channels. In this study, we have focused on two Ca2+ channels, the L-type voltage-gated Cav1.2 channel and the transient receptor potential channel TRPM3. Stimulation of either channel induces an intracellular signaling cascade leading to the activation of the transcription factor AP-1. The influx of Ca2+ ions into the cytoplasm is essential for this activity. We asked whether extracellular Zn2+ ions affect Cav1.2 or TRPM3-induced gene transcription following stimulation of the channels. The results show that extracellular Zn2+ ions reduced the activation of AP-1 by more than 80% following stimulation of either voltage-gated Cav1.2 channels or TRPM3 channels. Experiments performed with cells maintained in Ca2+-free medium revealed that Zn2+ ions cannot replace Ca2+ ions in inducing gene transcription via stimulation of Cav1.2 and TRPM3 channels. Re-addition of Ca2+ ions to the cell culture medium, however, restored the ability of these Ca2+ channels to induce a signaling cascade leading to the activation of AP-1. Secretory cells, including neurons and pancreatic β-cells, release Zn2+ ions during exocytosis. We propose that the released Zn2+ ions function as a negative feedback loop for stimulus-induced exocytosis by inhibiting Ca2+ channel signaling.
Collapse
Affiliation(s)
- Louisa Loviscach
- Department of Medical Biochemistry and Molecular Biology, Saarland University Medical Faculty, D-66421 Homburg, Germany.
| | | | | | | | | |
Collapse
|
16
|
The RNA-binding protein, HuD regulates proglucagon biosynthesis in pancreatic α cells. Biochem Biophys Res Commun 2020; 530:266-272. [PMID: 32828297 DOI: 10.1016/j.bbrc.2020.07.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 12/28/2022]
Abstract
Glucagon is a peptide hormone generated by pancreatic α cells. It is the counterpart of insulin and plays an essential role in the regulation of blood glucose level. Therefore, a tight regulation of glucagon levels is pivotal to maintain homeostasis of blood glucose. However, little is known about the mechanisms regulating glucagon biosynthesis. In this study, we demonstrate that the RNA-binding protein HuD regulates glucagon expression in pancreatic α cells. HuD was found in α cells from mouse pancreatic islet and mouse glucagonoma αTC1 cell line. Ribonucleoprotein immunoprecipitation analysis, followed by RT-qPCR showed the association of HuD with glucagon mRNA. Knockdown of HuD resulted in a reduction in both proglucagon expression and cellular glucagon level by decreasing its de novo synthesis. Reporter analysis using the EGFP reporter containing 3' untranslated region (3'UTR) of glucagon mRNA showed that HuD regulates proglucagon expression via its 3'UTR. In addition, the relative level of glucagon in the islets and plasma was lower in HuD knockout (KO) mice compared to age-matched control mice. Taken together, these results suggest that HuD is a novel factor regulating the biosynthesis of proglucagon in pancreatic α cells.
Collapse
|
17
|
Davis EM, Sandoval DA. Glucagon‐Like Peptide‐1: Actions and Influence on Pancreatic Hormone Function. Compr Physiol 2020; 10:577-595. [DOI: 10.1002/cphy.c190025] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
18
|
Hartig SM, Cox AR. Paracrine signaling in islet function and survival. J Mol Med (Berl) 2020; 98:451-467. [PMID: 32067063 DOI: 10.1007/s00109-020-01887-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/05/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023]
Abstract
The pancreatic islet is a dense cellular network comprised of several cell types with endocrine function vital in the control of glucose homeostasis, metabolism, and feeding behavior. Within the islet, endocrine hormones also form an intricate paracrine network with supportive cells (endothelial, neuronal, immune) and secondary signaling molecules regulating cellular function and survival. Modulation of these signals has potential consequences for diabetes development, progression, and therapeutic intervention. Beta cell loss, reduced endogenous insulin secretion, and dysregulated glucagon secretion are hallmark features of both type 1 and 2 diabetes that not only impact systemic regulation of glucose, but also contribute to the function and survival of cells within the islet. Advancing research and technology have revealed new islet biology (cellular identity and transcriptomes) and identified previously unrecognized paracrine signals and mechanisms (somatostatin and ghrelin paracrine actions), while shifting prior views of intraislet communication. This review will summarize the paracrine signals regulating islet endocrine function and survival, the disruption and dysfunction that occur in diabetes, and potential therapeutic targets to preserve beta cell mass and function.
Collapse
Affiliation(s)
- Sean M Hartig
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Aaron R Cox
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
| |
Collapse
|
19
|
Gilon P. The Role of α-Cells in Islet Function and Glucose Homeostasis in Health and Type 2 Diabetes. J Mol Biol 2020; 432:1367-1394. [PMID: 31954131 DOI: 10.1016/j.jmb.2020.01.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 12/23/2019] [Accepted: 01/06/2020] [Indexed: 01/09/2023]
Abstract
Pancreatic α-cells are the major source of glucagon, a hormone that counteracts the hypoglycemic action of insulin and strongly contributes to the correction of acute hypoglycemia. The mechanisms by which glucose controls glucagon secretion are hotly debated, and it is still unclear to what extent this control results from a direct action of glucose on α-cells or is indirectly mediated by β- and/or δ-cells. Besides its hyperglycemic action, glucagon has many other effects, in particular on lipid and amino acid metabolism. Counterintuitively, glucagon seems also required for an optimal insulin secretion in response to glucose by acting on its cognate receptor and, even more importantly, on GLP-1 receptors. Patients with diabetes mellitus display two main alterations of glucagon secretion: a relative hyperglucagonemia that aggravates hyperglycemia, and an impaired glucagon response to hypoglycemia. Under metabolic stress states, such as diabetes, pancreatic α-cells also secrete GLP-1, a glucose-lowering hormone, whereas the gut can produce glucagon. The contribution of extrapancreatic glucagon to the abnormal glucose homeostasis is unclear. Here, I review the possible mechanisms of control of glucagon secretion and the role of α-cells on islet function in healthy state. I discuss the possible causes of the abnormal glucagonemia in diabetes, with particular emphasis on type 2 diabetes, and I briefly comment the current antidiabetic therapies affecting α-cells.
Collapse
Affiliation(s)
- Patrick Gilon
- Université Catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Avenue Hippocrate 55 (B1.55.06), Brussels, B-1200, Belgium.
| |
Collapse
|
20
|
Müller TD, Finan B, Bloom SR, D'Alessio D, Drucker DJ, Flatt PR, Fritsche A, Gribble F, Grill HJ, Habener JF, Holst JJ, Langhans W, Meier JJ, Nauck MA, Perez-Tilve D, Pocai A, Reimann F, Sandoval DA, Schwartz TW, Seeley RJ, Stemmer K, Tang-Christensen M, Woods SC, DiMarchi RD, Tschöp MH. Glucagon-like peptide 1 (GLP-1). Mol Metab 2019; 30:72-130. [PMID: 31767182 PMCID: PMC6812410 DOI: 10.1016/j.molmet.2019.09.010] [Citation(s) in RCA: 893] [Impact Index Per Article: 178.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/10/2019] [Accepted: 09/22/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The glucagon-like peptide-1 (GLP-1) is a multifaceted hormone with broad pharmacological potential. Among the numerous metabolic effects of GLP-1 are the glucose-dependent stimulation of insulin secretion, decrease of gastric emptying, inhibition of food intake, increase of natriuresis and diuresis, and modulation of rodent β-cell proliferation. GLP-1 also has cardio- and neuroprotective effects, decreases inflammation and apoptosis, and has implications for learning and memory, reward behavior, and palatability. Biochemically modified for enhanced potency and sustained action, GLP-1 receptor agonists are successfully in clinical use for the treatment of type-2 diabetes, and several GLP-1-based pharmacotherapies are in clinical evaluation for the treatment of obesity. SCOPE OF REVIEW In this review, we provide a detailed overview on the multifaceted nature of GLP-1 and its pharmacology and discuss its therapeutic implications on various diseases. MAJOR CONCLUSIONS Since its discovery, GLP-1 has emerged as a pleiotropic hormone with a myriad of metabolic functions that go well beyond its classical identification as an incretin hormone. The numerous beneficial effects of GLP-1 render this hormone an interesting candidate for the development of pharmacotherapies to treat obesity, diabetes, and neurodegenerative disorders.
Collapse
Affiliation(s)
- T D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany.
| | - B Finan
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA
| | - S R Bloom
- Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - D D'Alessio
- Division of Endocrinology, Duke University Medical Center, Durham, NC, USA
| | - D J Drucker
- The Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, M5G1X5, Canada
| | - P R Flatt
- SAAD Centre for Pharmacy & Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - A Fritsche
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry, Department of Internal Medicine, University of Tübingen, Tübingen, Germany
| | - F Gribble
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council, Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - H J Grill
- Institute of Diabetes, Obesity and Metabolism, Department of Psychology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - J F Habener
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Harvard University, Boston, MA, USA
| | - J J Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - W Langhans
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - J J Meier
- Diabetes Division, St Josef Hospital, Ruhr-University Bochum, Bochum, Germany
| | - M A Nauck
- Diabetes Center Bochum-Hattingen, St Josef Hospital (Ruhr-Universität Bochum), Bochum, Germany
| | - D Perez-Tilve
- Department of Internal Medicine, University of Cincinnati-College of Medicine, Cincinnati, OH, USA
| | - A Pocai
- Cardiovascular & ImmunoMetabolism, Janssen Research & Development, Welsh and McKean Roads, Spring House, PA, 19477, USA
| | - F Reimann
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council, Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - D A Sandoval
- Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - T W Schwartz
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, DL-2200, Copenhagen, Denmark; Department of Biomedical Sciences, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - R J Seeley
- Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - K Stemmer
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - M Tang-Christensen
- Obesity Research, Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark
| | - S C Woods
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA
| | - R D DiMarchi
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA; Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - M H Tschöp
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Division of Metabolic Diseases, Department of Medicine, Technische Universität München, Munich, Germany; Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| |
Collapse
|
21
|
Noguchi GM, Huising MO. Integrating the inputs that shape pancreatic islet hormone release. Nat Metab 2019; 1:1189-1201. [PMID: 32694675 PMCID: PMC7378277 DOI: 10.1038/s42255-019-0148-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 11/07/2019] [Indexed: 02/06/2023]
Abstract
The pancreatic islet is a complex mini organ composed of a variety of endocrine cells and their support cells, which together tightly control blood glucose homeostasis. Changes in glucose concentration are commonly regarded as the chief signal controlling insulin-secreting beta cells, glucagon-secreting alpha cells and somatostatin-secreting delta cells. However, each of these cell types is highly responsive to a multitude of endocrine, paracrine, nutritional and neural inputs, which collectively shape the final endocrine output of the islet. Here, we review the principal inputs for each islet-cell type and the physiological circumstances in which these signals arise, through the prism of the insights generated by the transcriptomes of each of the major endocrine-cell types. A comprehensive integration of the factors that influence blood glucose homeostasis is essential to successfully improve therapeutic strategies for better diabetes management.
Collapse
Affiliation(s)
- Glyn M Noguchi
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, Davis, Davis, CA, USA
| | - Mark O Huising
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, Davis, Davis, CA, USA.
- Department of Physiology & Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, USA.
| |
Collapse
|
22
|
Ruz M, Carrasco F, Rojas P, Basfi-Fer K, Hernández MC, Pérez A. Nutritional Effects of Zinc on Metabolic Syndrome and Type 2 Diabetes: Mechanisms and Main Findings in Human Studies. Biol Trace Elem Res 2019; 188:177-188. [PMID: 30600497 DOI: 10.1007/s12011-018-1611-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/06/2018] [Indexed: 12/13/2022]
Abstract
Zinc (Zn) plays crucial roles in mammalian metabolism. There is increasing interest about the potential beneficial effects of Zn on the prevention or treatment of non-communicable diseases. This review critically analyzes the information related to the role of Zn on the metabolic syndrome (MetS) as well as type 2 diabetes (T2D), and summarizes the biological basis of these potential effects of Zn. There are several mechanisms by which Zn may help to prevent the development or progression of MetS and T2D, respectively. Zn is involved in both insulin secretion and action in peripheral tissues. Specifically, Zn has insulin-mimetic properties that increase the activity of the insulin signaling pathway. Zn modulates long-chain polyunsaturated fatty acids levels through its action on the absorption of essential fatty acids in the intestine and its subsequent desaturation. Zn is also involved in both the assembly of chylomicrons and lipoproteins as well as their clearance, and thus, plays a role in lipolysis regulation. Finally, Zn has been found to play a role in redox metabolism, and in turn, on blood pressure. The evidence related to the association between Zn status and occurrence of MetS is inconsistent. Although there are several studies reporting an inverse relationship between Zn status or dietary Zn intake and MetS prevalence, others found a direct relationship between Zn status and MetS prevalence. Intervention studies also provide confusing information about this issue, making it hard to reach firm conclusions. Zn as part of the treatment for patients with T2D has been shown to have positive responses in terms of glucose control outcomes, but only among those with Zn deficiency.
Collapse
Affiliation(s)
- Manuel Ruz
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile.
| | - Fernando Carrasco
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Pamela Rojas
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Karen Basfi-Fer
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Maria Catalina Hernández
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Alvaro Pérez
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| |
Collapse
|
23
|
Zhao T, Huang Q, Su Y, Sun W, Huang Q, Wei W. Zinc and its regulators in pancreas. Inflammopharmacology 2019; 27:453-464. [PMID: 30756223 DOI: 10.1007/s10787-019-00573-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/02/2019] [Indexed: 12/12/2022]
Abstract
Studies have demonstrated that susceptibility to type 2 diabetes (T2D) is influenced by common polymorphism in the zinc transporter 8 gene SLC30A8, providing novel insight into the role of zinc in diabetes. Intriguingly, zinc participates in every step of the process, including insulin synthesis, crystallization, storage, secretion and signaling. Zinc deficiency or overload is associated with various disorders, such as diabetes, cardiovascular disease and obesity. Zinc supplementation is considered as an effective means of treating or preventing T2D in people with certain SLC30A8 genotypes. Three important protein families-zinc transporters (ZnTs), zinc importers (ZiPs) and metallothionein (MT)-participate in maintaining zinc homeostasis. Here, we review research on the physiological characteristics of zinc and its role in the pancreas and homeostasis regulation mechanisms, along with the latest research on the structure and function of ZnT/ZiP and MT. In addition, we summarize the advancements in research on SLC30A8 gene polymorphism in search of a mechanism to explain the relationship between the R risk allele and zinc transporter activity.
Collapse
Affiliation(s)
- Tianjiao Zhao
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China
| | - Qiongfang Huang
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China
| | - Yangni Su
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China
| | - Wuyi Sun
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China
| | - Qiong Huang
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China.
| | - Wei Wei
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China.
| |
Collapse
|
24
|
Stevenson MJ, Uyeda KS, Harder NHO, Heffern MC. Metal-dependent hormone function: the emerging interdisciplinary field of metalloendocrinology. Metallomics 2019; 11:85-110. [PMID: 30270362 PMCID: PMC10249669 DOI: 10.1039/c8mt00221e] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
For over 100 years, there has been an incredible amount of knowledge amassed concerning hormones in the endocrine system and their central role in human health. Hormones represent a diverse group of biomolecules that are released by glands, communicate signals to their target tissue, and are regulated by feedback loops to maintain organism health. Many disease states, such as diabetes and reproductive disorders, stem from misregulation or dysfunction of hormones. Increasing research is illuminating the intricate roles of metal ions in the endocrine system where they may act advantageously in concert with hormones or deleteriously catalyze hormone-associated disease states. As the critical role of metal ions in the endocrine system becomes more apparent, it is increasingly important to untangle the complex mechanisms underlying the connections between inorganic biochemistry and hormone function to understand and control endocrinological phenomena. This tutorial review harmonizes the interdisciplinary fields of endocrinology and inorganic chemistry in the newly-termed field of "metalloendocrinology". We describe examples linking metals to both normal and aberrant hormone function with a focus on highlighting insight to molecular mechanisms. Hormone activities related to both essential metal micronutrients, such as copper, iron, zinc, and calcium, and disruptive nonessential metals, such as lead and cadmium are discussed.
Collapse
Affiliation(s)
- Michael J Stevenson
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
| | | | | | | |
Collapse
|
25
|
Perez A, Rojas P, Carrasco F, Basfi-Fer K, Perez-Bravo F, Codoceo J, Inostroza J, Galgani JE, Gilmore LA, Ruz M. Association between zinc nutritional status and glycemic control in individuals with well-controlled type-2 diabetes. J Trace Elem Med Biol 2018; 50:560-565. [PMID: 29631853 DOI: 10.1016/j.jtemb.2018.03.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/08/2018] [Accepted: 03/22/2018] [Indexed: 11/25/2022]
Abstract
BACKGROUND/OBJECTIVE Interest in healthy properties of food and nutrients as co-adjuvant in type-2 diabetes therapy has increased in recent years. Zinc supplementation trials have shown improvements in glycemic control in these patients, although it seems dependent on zinc status of the individuals. The objective of this study was to evaluate the relationship between zinc nutritional status and glucose homeostasis in patients with type-2 diabetes. SUBJECTS/METHODS Eighty patients with well controlled type-2 diabetes were recruited and clinical, anthropometric and dietary evaluations were performed. One week after, insulin sensitivity and beta cell function were assessed by a modified Frequently Sampled Intravenous Glucose Tolerance Test. Zinc status was assessed by plasma zinc and the size of rapidly Exchangeable Zinc Pool (EZP); zinc intake was also determined. Glucagon concentration was evaluated in a subsample of 36 patients. RESULTS Patients presented a normal zinc status although zinc intake was lower than recommended. Overall, no associations were observed between zinc status and glycemic control markers. Nevertheless, positive correlations were observed between EZP and fasting insulin concentration (ρ = 0.393, p = 0.021) and HOMA-IR (ρ = 0.386, p = 0.024) in women, and between plasma zinc concentration and HbA1c (ρ = 0.342, p = 0.020) in men. CONCLUSIONS No significant associations were found between zinc status and glycemic control parameters in patients with well-controlled type 2 diabetes and normal zinc status, although low-degree gender-dependent associations were observed. Further research is required to assess the role of zinc status in zinc deficient patients.
Collapse
Affiliation(s)
- Alvaro Perez
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Pamela Rojas
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Fernando Carrasco
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Karen Basfi-Fer
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | | | - Juana Codoceo
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Jorge Inostroza
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Jose E Galgani
- Department of Nutrition, Diabetes and Metabolism, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile; Department of Health Sciences-Nutrition and Dietetics, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - L Anne Gilmore
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
| | - Manuel Ruz
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile.
| |
Collapse
|
26
|
Pérez A, Rojas P, Carrasco F, Basfi-Fer K, Pérez-Bravo F, Codoceo J, Inostroza J, Ruz M. Zinc Supplementation Does Not Affect Glucagon Response to Intravenous Glucose and Insulin Infusion in Patients with Well-Controlled Type 2 Diabetes. Biol Trace Elem Res 2018; 185:255-261. [PMID: 29374382 DOI: 10.1007/s12011-018-1249-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/15/2018] [Indexed: 12/21/2022]
Abstract
Glucagon dysregulation is an essential component in the pathophysiology of type 2 diabetes. Studies in vitro and in animal models have shown that zinc co-secreted with insulin suppresses glucagon secretion. Zinc supplementation improves blood glucose control in patients with type 2 diabetes, although there is little information about how zinc supplementation may affect glucagon secretion. The objective of this study was to evaluate the effect of 1-year zinc supplementation on fasting plasma glucagon concentration and in response to intravenous glucose and insulin infusion in patients with type 2 diabetes. A cross-sectional study was performed after 1-year of intervention with 30 mg/day zinc supplementation or a placebo on 28 patients with type 2 diabetes. Demographic, anthropometric, and biochemical parameters were determined. Fasting plasma glucagon and in response to intravenous glucose and insulin infusion were evaluated. Patients of both placebo and supplemented groups presented a well control of diabetes, with mean values of fasting blood glucose and glycated hemoglobin within the therapeutic goals established by ADA. No significant differences were observed in plasma glucagon concentration, glucagon/glucose ratio or glucagon/insulin ratio fasting, after glucose or after insulin infusions between placebo and supplemented groups. No significant effects of glucose or insulin infusions were observed on plasma glucagon concentration. One-year zinc supplementation did not affect fasting plasma glucagon nor response to intravenous glucose or insulin infusion in well-controlled type 2 diabetes patients with an adequate zinc status.
Collapse
Affiliation(s)
- Alvaro Pérez
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Pamela Rojas
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Fernando Carrasco
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Karen Basfi-Fer
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Francisco Pérez-Bravo
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Juana Codoceo
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Jorge Inostroza
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile
| | - Manuel Ruz
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile.
| |
Collapse
|
27
|
Abstract
Islets of Langerhans are islands of endocrine cells scattered throughout the pancreas. A number of new studies have pointed to the potential for conversion of non-β islet cells in to insulin-producing β-cells to replenish β-cell mass as a means to treat diabetes. Understanding normal islet cell mass and function is important to help advance such treatment modalities: what should be the target islet/β-cell mass, does islet architecture matter to energy homeostasis, and what may happen if we lose a particular population of islet cells in favour of β-cells? These are all questions to which we will need answers for islet replacement therapy by transdifferentiation of non-β islet cells to be a reality in humans. We know a fair amount about the biology of β-cells but not quite as much about the other islet cell types. Until recently, we have not had a good grasp of islet mass and distribution in the human pancreas. In this review, we will look at current data on islet cells, focussing more on non-β cells, and on human pancreatic islet mass and distribution.
Collapse
Affiliation(s)
- Gabriela Da Silva Xavier
- Section of Functional Genomics and Cell Biology, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Edgbaston B15 2TT, UK.
| |
Collapse
|
28
|
Zhou C, Routh VH. Thioredoxin-1 Overexpression in the Ventromedial Nucleus of the Hypothalamus Preserves the Counterregulatory Response to Hypoglycemia During Type 1 Diabetes in Male Rats. Diabetes 2018; 67:120-130. [PMID: 29079703 PMCID: PMC5741147 DOI: 10.2337/db17-0930] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/23/2017] [Indexed: 12/21/2022]
Abstract
We previously showed that the glutathione precursor, N-acetylcysteine (NAC), prevented hypoglycemia-associated autonomic failure (HAAF) and impaired activation of ventromedial hypothalamus (VMH) glucose-inhibited (GI) neurons by low glucose after recurrent hypoglycemia (RH) in nondiabetic rats. However, NAC does not normalize glucose sensing by VMH GI neurons when RH occurs during diabetes. We hypothesized that recruiting the thioredoxin (Trx) antioxidant defense system would prevent HAAF and normalize glucose sensing after RH in diabetes. To test this hypothesis, we overexpressed Trx-1 (cytosolic form of Trx) in the VMH of rats with streptozotocin (STZ)-induced type 1 diabetes. The counterregulatory response (CRR) to hypoglycemia in vivo and the activation of VMH GI neurons in low glucose using membrane potential sensitive dye in vitro was measured before and after RH. VMH Trx-1 overexpression normalized both the CRR and glucose sensing by VMH GI neurons in STZ rats. VMH Trx-1 overexpression also lowered the insulin requirement to prevent severe hyperglycemia in STZ rats. However, like NAC, VMH Trx-1 overexpression did not prevent HAAF or normalize activation of VMH GI neurons by low glucose in STZ rats after RH. We conclude that preventing HAAF in type 1 diabetes may require the recruitment of both antioxidant systems.
Collapse
Affiliation(s)
- Chunxue Zhou
- Department of Pharmacology, Physiology and Neurosciences, New Jersey Medical School, Rutgers University, Newark, NJ
| | - Vanessa H Routh
- Department of Pharmacology, Physiology and Neurosciences, New Jersey Medical School, Rutgers University, Newark, NJ
| |
Collapse
|
29
|
Yu T, Jiang Z, Liu L, Fan Z. Decrease of γ-aminobutyric acid and zinc ions in the islet periportal circulation stimulates glucagon secretion during hypoglycemia. Exp Ther Med 2017; 15:2507-2511. [PMID: 29467850 DOI: 10.3892/etm.2017.5670] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 07/07/2017] [Indexed: 11/05/2022] Open
Abstract
The present study assessed the effects of γ-aminobutyric acid (GABA) from β-cells on glucose levels and glucagon secretion, and identified channels via which glucagon secretion is initiated. An in vivo experiment was performed containing three groups: Intrapancreatic artery infusion of GABA alone, GABA plus insulin or insulin alone in rats with diabetes. Rats infused with GABA and insulin were also subdivided in groups receiving additional infusion of K+-channel activator diazoxide (DIA), K+-channel blocker tolbutamide (TLB) and calcium channel blocker nifedipine (NIF). In the hypoglycemic state, termination of infusion of insulin and insulin plus GABA resulted in signaling to the α-cells to secrete glycogen, while that of GABA alone did not. However, intrapancreatic artery infusion of K+-channel activator DIA, K+-channel blocker TLB or calcium channel blocker NIF in addition to GABA and insulin had no effect on glucagon secretion. In conclusion, if the delivery of insulin or GABA plus insulin in rats with hypoglycemia is terminated, β-cells are stimulated and signal the α-cells to secrete glucagon. Thus, the detection of a sudden decrease in zinc levels by β-cells as well as a decrease in GABA in the periportal circulation induces signaling to α-cells to stimulate them to secrete glucagon.
Collapse
Affiliation(s)
- Tingting Yu
- Department of Digestive Medicine, Institute of Digestive Endoscopy, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210000, P.R. China.,Department of Gastroenterology, The First People's Hospital of Yancheng, Yancheng, Jiangsu 224000, P.R. China
| | - Zhonghua Jiang
- Department of Gastroenterology, The First People's Hospital of Yancheng, Yancheng, Jiangsu 224000, P.R. China
| | - Li Liu
- Department of Digestive Medicine, Institute of Digestive Endoscopy, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210000, P.R. China
| | - Zhining Fan
- Department of Digestive Medicine, Institute of Digestive Endoscopy, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210000, P.R. China
| |
Collapse
|
30
|
Inthongkaew P, Chatsumpun N, Supasuteekul C, Kitisripanya T, Putalun W, Likhitwitayawuid K, Sritularak B. α-Glucosidase and pancreatic lipase inhibitory activities and glucose uptake stimulatory effect of phenolic compounds from Dendrobium formosum. REVISTA BRASILEIRA DE FARMACOGNOSIA-BRAZILIAN JOURNAL OF PHARMACOGNOSY 2017. [DOI: 10.1016/j.bjp.2017.05.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
31
|
Müller TD, Finan B, Clemmensen C, DiMarchi RD, Tschöp MH. The New Biology and Pharmacology of Glucagon. Physiol Rev 2017; 97:721-766. [PMID: 28275047 DOI: 10.1152/physrev.00025.2016] [Citation(s) in RCA: 206] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In the last two decades we have witnessed sizable progress in defining the role of gastrointestinal signals in the control of glucose and energy homeostasis. Specifically, the molecular basis of the huge metabolic benefits in bariatric surgery is emerging while novel incretin-based medicines based on endogenous hormones such as glucagon-like peptide 1 and pancreas-derived amylin are improving diabetes management. These and related developments have fostered the discovery of novel insights into endocrine control of systemic metabolism, and in particular a deeper understanding of the importance of communication across vital organs, and specifically the gut-brain-pancreas-liver network. Paradoxically, the pancreatic peptide glucagon has reemerged in this period among a plethora of newly identified metabolic macromolecules, and new data complement and challenge its historical position as a gut hormone involved in metabolic control. The synthesis of glucagon analogs that are biophysically stable and soluble in aqueous solutions has promoted biological study that has enriched our understanding of glucagon biology and ironically recruited glucagon agonism as a central element to lower body weight in the treatment of metabolic disease. This review summarizes the extensive historical record and the more recent provocative direction that integrates the prominent role of glucagon in glucose elevation with its under-acknowledged effects on lipids, body weight, and vascular health that have implications for the pathophysiology of metabolic diseases, and the emergence of precision medicines to treat metabolic diseases.
Collapse
Affiliation(s)
- T D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - B Finan
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - C Clemmensen
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - R D DiMarchi
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - M H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| |
Collapse
|
32
|
Chabosseau P, Rutter GA. Zinc and diabetes. Arch Biochem Biophys 2016; 611:79-85. [DOI: 10.1016/j.abb.2016.05.022] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 05/09/2016] [Accepted: 05/31/2016] [Indexed: 01/09/2023]
|
33
|
Abstract
Zinc (Zn) is important in a number of processes related to insulin secretion and insulin activity in peripheral tissues, making this element an interesting potential co-adjuvant in the treatment of patients with type 2 diabetes (T2D). This issue has been matter of interest in recent years. The available evidence is analyzed in this review. Information from epidemiologic studies evaluating the relationship between Zn and T2D is inconsistent. Furthermore, few studies examined the association between Zn status and insulin action and/or glucose homeostasis. In terms of usefulness of Zn as a preventive agent for T2D development, information is insufficient to reach firm conclusions. Results from Zn supplementation trials found some positive effects only in those with initial sub normal Zn status in a significant proportion of individuals. In conclusion, the effect of Zn on patients with type 2 diabetes is still an open question, and better study designs are needed to clarify the real impact and characteristics of the Zn-diabetes interaction.
Collapse
Affiliation(s)
- Manuel Ruz
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Postal Code 8380453, Santiago, Chile.
| | - Fernando Carrasco
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Postal Code 8380453, Santiago, Chile
| | - Andrés Sánchez
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Postal Code 8380453, Santiago, Chile
| | - Alvaro Perez
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Postal Code 8380453, Santiago, Chile
| | - Pamela Rojas
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Postal Code 8380453, Santiago, Chile
| |
Collapse
|
34
|
Briant L, Salehi A, Vergari E, Zhang Q, Rorsman P. Glucagon secretion from pancreatic α-cells. Ups J Med Sci 2016; 121:113-9. [PMID: 27044683 PMCID: PMC4900066 DOI: 10.3109/03009734.2016.1156789] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 02/16/2016] [Indexed: 11/13/2022] Open
Abstract
Type 2 diabetes involves a ménage à trois of impaired glucose regulation of pancreatic hormone release: in addition to impaired glucose-induced insulin secretion, the release of the hyperglycaemic hormone glucagon becomes dysregulated; these last-mentioned defects exacerbate the metabolic consequences of hypoinsulinaemia and are compounded further by hypersecretion of somatostatin (which inhibits both insulin and glucagon secretion). Glucagon secretion has been proposed to be regulated by either intrinsic or paracrine mechanisms, but their relative significance and the conditions under which they operate are debated. Importantly, the paracrine and intrinsic modes of regulation are not mutually exclusive; they could operate in parallel to control glucagon secretion. Here we have applied mathematical modelling of α-cell electrical activity as a novel means of dissecting the processes that underlie metabolic regulation of glucagon secretion. Our analyses indicate that basal hypersecretion of somatostatin and/or increased activity of somatostatin receptors may explain the loss of adequate counter-regulation under hypoglycaemic conditions, as well as the physiologically inappropriate stimulation of glucagon secretion during hyperglycaemia seen in diabetic patients. We therefore advocate studying the interaction of the paracrine and intrinsic mechanisms; unifying these processes may give a more complete picture of the regulation of glucagon secretion from α-cells than studying the individual parts.
Collapse
Affiliation(s)
- Linford Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK;
| | - Albert Salehi
- Metabolic Research, Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Elisa Vergari
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK;
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK;
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK;
- Metabolic Research, Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| |
Collapse
|
35
|
Gylfe E. Glucose control of glucagon secretion-'There's a brand-new gimmick every year'. Ups J Med Sci 2016; 121:120-32. [PMID: 27044660 PMCID: PMC4900067 DOI: 10.3109/03009734.2016.1154905] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 02/10/2016] [Accepted: 02/11/2016] [Indexed: 11/13/2022] Open
Abstract
Glucagon from the pancreatic α-cells is a major blood glucose-regulating hormone whose most important role is to prevent hypoglycaemia that can be life-threatening due to the brain's strong dependence on glucose as energy source. Lack of blood glucose-lowering insulin after malfunction or autoimmune destruction of the pancreatic β-cells is the recognized cause of diabetes, but recent evidence indicates that diabetic hyperglycaemia would not develop unless lack of insulin was accompanied by hypersecretion of glucagon. Glucagon release has therefore become an increasingly important target in diabetes management. Despite decades of research, an understanding of how glucagon secretion is regulated remains elusive, and fundamentally different mechanisms continue to be proposed. The autonomous nervous system is an important determinant of glucagon release, but it is clear that secretion is also directly regulated within the pancreatic islets. The present review focuses on pancreatic islet mechanisms involved in glucose regulation of glucagon release. It will be argued that α-cell-intrinsic processes are most important for regulation of glucagon release during recovery from hypoglycaemia and that paracrine inhibition by somatostatin from the δ-cells shapes pulsatile glucagon release in hyperglycaemia. The electrically coupled β-cells ultimately determine islet hormone pulsatility by releasing synchronizing factors that affect the α- and δ-cells.
Collapse
Affiliation(s)
- Erik Gylfe
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| |
Collapse
|
36
|
Ishihara H, Wollheim CB. Is zinc an intra-islet regulator of glucagon secretion? Diabetol Int 2016; 7:106-110. [PMID: 30603252 DOI: 10.1007/s13340-016-0259-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 01/26/2016] [Indexed: 11/26/2022]
Abstract
More than a decade ago, zinc was suggested to have a role as an intra-islet regulator of glucagon secretion. Several lines of experimental evidence have since provided support for this hypothesis, though contradictory observations have also been reported. Meanwhile, Slc30A/ZnT8, a zinc transporter expressed in insulin and glucagon secretory granules, was identified. Furthermore, genome wide association analyses revealed it to be a candidate causative gene for type 2 diabetes mellitus. Recent progress in gene manipulation in animals yielded considerable information on the role of zinc in islet cells. In this mini-review, data pertaining the roles played by zinc in islet hormone secretion are summarized and discussed.
Collapse
Affiliation(s)
- Hisamitsu Ishihara
- 1Division of Diabetes and Metabolism, Nihon University School of Medicine, 30-1 Oyaguchi-kamicho, Itabashi, Tokyo 173-8610 Japan
| | - Claes B Wollheim
- 2Department of Cell Physiology and Metabolism, University Medical Centre, rue Michel-Servet 1, 1211 Geneva 4, Switzerland
| |
Collapse
|
37
|
Abstract
OBJECTIVE There is general recognition that insulin and glucagon are the main hormones involved in the pathophysiology of diabetes, but the role of glucagon in diabetes is complex and in some circumstances controversial. The increasing appreciation of the role of glucagon in currently used hypoglycemic agents and the ongoing development of glucagon-targeted therapies underscores glucagon's important contribution in optimizing diabetes management. The current review provides a background on glucagon physiology and pathophysiology and an update for investigators, endocrinologists, and other healthcare providers on glucagon-modulating therapies. METHODS A literature review was conducted utilizing published literature in PubMed and AccessMedicine including the years 1922-2015 using the following key words: glucagon, bihormonal, diabetes mellitus, glucagon antagonists, glucagon-targeted therapies. RESULTS Glucagon is a counterregulatory hormone that promotes hepatic glucose production, thus preventing hypoglycemia in normal physiology. In patients with diabetes mellitus, glucagon secretion may be unregulated, which contributes to problems with glucose homeostasis. Several of the most effective therapies for diabetes have been found to suppress glucagon secretion or action, which may contribute to their success. Additionally, glucagon-specific targeted therapies, such as glucagon receptor antagonists, are being studied at a basic and clinical level. CONCLUSION Glucagon plays an important role in contributing to hyperglycemia in patients with diabetes. Utilizing hypoglycemic agents that decrease glucagon secretion or inhibit glucagon action can help improve glycemic control, making these agents a valuable resource in diabetes therapy.
Collapse
|
38
|
Ranasinghe P, Pigera S, Galappatthy P, Katulanda P, Constantine GR. Zinc and diabetes mellitus: understanding molecular mechanisms and clinical implications. ACTA ACUST UNITED AC 2015; 23:44. [PMID: 26381880 PMCID: PMC4573932 DOI: 10.1186/s40199-015-0127-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/20/2015] [Indexed: 01/08/2023]
Abstract
Background Diabetes mellitus is a leading cause of morbidity and mortality worldwide. Studies have shown that Zinc has numerous beneficial effects in both type-1 and type-2 diabetes. We aim to evaluate the literature on the mechanisms and molecular level effects of Zinc on glycaemic control, β-cell function, pathogenesis of diabetes and its complications. Methods A review of published studies reporting mechanisms of action of Zinc in diabetes was undertaken in PubMed and SciVerse Scopus medical databases using the following search terms in article title, abstract or keywords; (“Zinc” or “Zn”) and (“mechanism” or “mechanism of action” or “action” or “effect” or “pathogenesis” or “pathology” or “physiology” or “metabolism”) and (“diabetes” or “prediabetes” or “sugar” or “glucose” or “insulin”). Results The literature search identified the following number of articles in the two databases; PubMed (n = 1799) and SciVerse Scopus (n = 1879). After removing duplicates the total number of articles included in the present review is 111. Our results show that Zinc plays an important role in β-cell function, insulin action, glucose homeostasis and the pathogenesis of diabetes and its complications. Conclusion Numerous in-vitro and in-vivo studies have shown that Zinc has beneficial effects in both type-1 and type-2 diabetes. However further randomized double-blinded placebo-controlled clinical trials conducted for an adequate duration, are required to establish therapeutic safety in humans. Electronic supplementary material The online version of this article (doi:10.1186/s40199-015-0127-4) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Priyanga Ranasinghe
- Department of Pharmacology, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka.
| | - Shehani Pigera
- Department of Pharmacology, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka
| | | | - Prasad Katulanda
- Diabetes Research Unit, Department of Clinical Medicine, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka
| | - Godwin R Constantine
- Diabetes Research Unit, Department of Clinical Medicine, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka
| |
Collapse
|
39
|
Mundinger TO, Cooper E, Coleman MP, Taborsky GJ. Short-term diabetic hyperglycemia suppresses celiac ganglia neurotransmission, thereby impairing sympathetically mediated glucagon responses. Am J Physiol Endocrinol Metab 2015; 309:E246-55. [PMID: 26037249 PMCID: PMC4525110 DOI: 10.1152/ajpendo.00140.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/25/2015] [Indexed: 01/09/2023]
Abstract
Short-term hyperglycemia suppresses superior cervical ganglia neurotransmission. If this ganglionic dysfunction also occurs in the islet sympathetic pathway, sympathetically mediated glucagon responses could be impaired. Our objectives were 1) to test for a suppressive effect of 7 days of streptozotocin (STZ) diabetes on celiac ganglia (CG) activation and on neurotransmitter and glucagon responses to preganglionic nerve stimulation, 2) to isolate the defect in the islet sympathetic pathway to the CG itself, and 3) to test for a protective effect of the WLD(S) mutation. We injected saline or nicotine in nondiabetic and STZ-diabetic rats and measured fos mRNA levels in whole CG. We electrically stimulated the preganglionic or postganglionic nerve trunk of the CG in nondiabetic and STZ-diabetic rats and measured portal venous norepinephrine and glucagon responses. We repeated the nicotine and preganglionic nerve stimulation studies in nondiabetic and STZ-diabetic WLD(S) rats. In STZ-diabetic rats, the CG fos response to nicotine was suppressed, and the norepinephrine and glucagon responses to preganglionic nerve stimulation were impaired. In contrast, the norepinephrine and glucagon responses to postganglionic nerve stimulation were normal. The CG fos response to nicotine, and the norepinephrine and glucagon responses to preganglionic nerve stimulation, were normal in STZ-diabetic WLD(S) rats. In conclusion, short-term hyperglycemia's suppressive effect on nicotinic acetylcholine receptors of the CG impairs sympathetically mediated glucagon responses. WLD(S) rats are protected from this dysfunction. The implication is that this CG dysfunction may contribute to the impaired glucagon response to insulin-induced hypoglycemia seen early in type 1 diabetes.
Collapse
MESH Headings
- Animals
- Diabetes Mellitus, Type 1/blood
- Diabetes Mellitus, Type 1/complications
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/physiopathology
- Down-Regulation/drug effects
- Electric Stimulation
- Ganglia, Sympathetic/drug effects
- Ganglia, Sympathetic/metabolism
- Ganglia, Sympathetic/physiopathology
- Ganglionic Stimulants/pharmacology
- Glucagon/blood
- Glucagon/metabolism
- Hyperglycemia/etiology
- Islets of Langerhans/drug effects
- Islets of Langerhans/innervation
- Islets of Langerhans/metabolism
- Male
- Mutant Proteins/metabolism
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Nicotinic Agonists/pharmacology
- Norepinephrine/blood
- Norepinephrine/metabolism
- Proto-Oncogene Proteins c-fos/genetics
- Proto-Oncogene Proteins c-fos/metabolism
- Rats, Sprague-Dawley
- Rats, Transgenic
- Rats, Wistar
- Receptors, Nicotinic/chemistry
- Receptors, Nicotinic/metabolism
- Synaptic Transmission/drug effects
- Wallerian Degeneration/complications
Collapse
Affiliation(s)
| | - Ellis Cooper
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Michael P Coleman
- The Babraham Institute, Babraham Research Campus, Babraham, Cambridge, United Kingdom; and
| | - Gerald J Taborsky
- Department of Medicine, University of Washington, Seattle, Washington; Veterans Affairs Puget Sound Health Care System, Seattle, Washington
| |
Collapse
|
40
|
Diethyldithiocarbamate-mediated zinc ion chelation reveals role of Cav2.3 channels in glucagon secretion. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:953-64. [DOI: 10.1016/j.bbamcr.2015.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 12/28/2014] [Accepted: 01/03/2015] [Indexed: 12/13/2022]
|
41
|
Singla N, Dhawan DK. Modulation of (14) C-labeled glucose metabolism by zinc during aluminium induced neurodegeneration. J Neurosci Res 2015; 93:1434-41. [PMID: 25908409 DOI: 10.1002/jnr.23596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 04/08/2015] [Accepted: 04/08/2015] [Indexed: 12/24/2022]
Abstract
Aluminium (Al) is one of the most prominent metals in the environment and is responsible for causing several neurological disorders, including Alzheimer's disease. On the other hand, zinc (Zn) is an essential micronutrient that is involved in regulating brain development and function. The present study investigates the protective potential of Zn in the uptake of (14) C-labeled amino acids and glucose and their turnover in rat brain slices during Al intoxication. Male Sprague Dawley rats (140-160 g) were divided into four different groups: normal control, Al treated (100 mg/kg body weight/day via oral gavage), Zn treated (227 mg/liter in drinking water), and Al + Zn treated. Radiorespirometric assay revealed an increase in glucose turnover after Al exposure that was attenuated after Zn treatment. Furthermore, the uptake of (14) C-labeled glucose was increased after Al treatment but was appreciably decreased upon Zn supplementation. In addition, the uptakes of (14) C-lysine, (14) C-leucine, and (14) C-aspartic acid were also found to be elevated following Al exposure but were decreased after Zn treatment. Al treatment also caused alterations in the neurohistoarchitecture of the brain, which were improved after Zn coadministration. Therefore, the present study suggests that Zn provides protection against Al-induced neurotoxicity by regulating glucose and amino acid uptake in rats, indicating that Zn could be a potential candidate for the treatment of various neurodegenerative disorders.
Collapse
Affiliation(s)
- Neha Singla
- Department of Biophysics, Panjab University, Chandigarh, India
| | - D K Dhawan
- Department of Biophysics, Panjab University, Chandigarh, India
| |
Collapse
|
42
|
Eickhoff H, Louro T, Matafome P, Seiça R, Castro e Sousa F. Glucagon secretion after metabolic surgery in diabetic rodents. J Endocrinol 2014; 223:255-65. [PMID: 25274989 DOI: 10.1530/joe-14-0445] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Excessive or inadequate glucagon secretion promoting hepatic gluconeogenesis and glycogenolysis is believed to contribute to hyperglycemia in patients with type 2 diabetes. Currently, metabolic surgery is an accepted treatment for obese patients with type 2 diabetes and has been shown to improve glycemic control in Goto-Kakizaki (GK) rats, a lean animal model for type 2 diabetes. However, the effects of surgery on glucagon secretion are not yet well established. In this study, we randomly assigned forty 12- to 14-week-old GK rats to four groups: control group (GKC), sham surgery (GKSS), sleeve gastrectomy (GKSG), and gastric bypass (GKGB). Ten age-matched Wistar rats served as a non-diabetic control group (WIC). Glycemic control was assessed before and 4 weeks after surgery. Fasting- and mixed-meal-induced plasma levels of insulin and glucagon were measured. Overall glycemic control improved in GKSG and GKGB rats. Fasting insulin levels in WIC rats were similar to those for GKC or GKSS rats. Fasting glucagon levels were highest in GKGB rats. Whereas WIC, GKC, and GKSS rats showed similar glucagon levels, without any significant meal-induced variation, a significant rise occurred in GKSG and GKGB rats, 30 min after a mixed meal, which was maintained at 60 min. Both GKSG and GKGB rats showed an elevated glucagon:insulin ratio at 60 min in comparison with all other groups. Surprisingly, the augmented post-procedural glucagon secretion was accompanied by an improved overall glucose metabolism in GKSG and GKGB rats. Understanding the role of glucagon in the pathophysiology of type 2 diabetes requires further research.
Collapse
Affiliation(s)
- Hans Eickhoff
- Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - Teresa Louro
- Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - Paulo Matafome
- Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - Raquel Seiça
- Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - Francisco Castro e Sousa
- Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal Obesity CenterHospital de Santiago, EN 10, km 37, 2900-722 Setubal, PortugalFaculty of MedicineInstitutes of PhysiologyBiomedical Imaging and Life Sciences (IBILI)University of Coimbra, Polo III, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, PortugalDepartment of Surgery AUniversity Hospital of Coimbra, Rua Fonseca Pinto, 3000-075 Coimbra, PortugalFaculty of MedicineUniversity of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| |
Collapse
|
43
|
Davidson HW, Wenzlau JM, O'Brien RM. Zinc transporter 8 (ZnT8) and β cell function. Trends Endocrinol Metab 2014; 25:415-24. [PMID: 24751356 PMCID: PMC4112161 DOI: 10.1016/j.tem.2014.03.008] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 03/17/2014] [Accepted: 03/19/2014] [Indexed: 02/07/2023]
Abstract
Human pancreatic β cells have exceptionally high zinc content. In β cells the highest zinc concentration is in insulin secretory granules, from which it is cosecreted with the hormone. Uptake of zinc into secretory granules is mainly mediated by zinc transporter 8 (ZnT8), the product of the SLC30A8 [solute carrier family 30 (zinc transporter), member 8] gene. The minor alleles of several single-nucleotide polymorphisms (SNPs) in SLC30A8 are associated with decreased risk of type 2 diabetes (T2D), but the precise mechanisms underlying the protective effects remain uncertain. In this article we review current knowledge of the role of ZnT8 in maintaining zinc homeostasis in β cells, its role in glucose metabolism based on knockout mouse studies, and current theories regarding the link between ZnT8 function and T2D.
Collapse
Affiliation(s)
- Howard W Davidson
- Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA; Integrated Department of Immunology, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - Janet M Wenzlau
- Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Richard M O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
| |
Collapse
|
44
|
Abstract
Zinc is an essential nutrient with tremendous importance for human health, and zinc deficiency is a severe risk factor for increased mortality and morbidity. As abnormal zinc homeostasis causes diabetes, and because the pancreatic β-cell contains the highest zinc content of any known cell type, it is of interest to know how zinc fluxes are controlled in β-cells. The understanding of zinc homeostasis has been boosted by the discovery of multiprotein families of zinc transporters, and one of them - zinc transporter 8 (ZnT8) - is abundantly and specifically expressed in the pancreatic islets of Langerhans. In this review, we discuss the evidence for a physiological role of ZnT8 in the formation of zinc-insulin crystals, the physical form in which most insulin is stored in secretory granules. In addition, we cross-examine this information, collected in genetically modified mouse strains, to the knowledge that genetic variants of the human ZnT8 gene predispose to the onset of type 2 diabetes and that epitopes on the ZnT8 protein trigger autoimmunity in patients with type 1 diabetes. The overall conclusion is that we are still at the dawn of a complete understanding of how zinc homeostasis operates in normal β-cells and how abnormalities lead to β-cell dysfunction and diabetes. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2012.00199.x, 2012).
Collapse
Affiliation(s)
- Katleen Lemaire
- Gene Expression Unit, Department of Molecular Cell Biology, KU Leuven, Leuven, Belgium
| | | | - Frans Schuit
- Gene Expression Unit, Department of Molecular Cell Biology, KU Leuven, Leuven, Belgium
| |
Collapse
|
45
|
Abstract
Glucose homeostasis is precisely regulated by glucagon and insulin, which are released by pancreatic α- and β-cells, respectively. While β-cells have been the focus of intense research, less is known about α-cell function and the actions of glucagon. In recent years, the study of this endocrine cell type has experienced a renewed drive. The present review contains a summary of established concepts as well as new information about the regulation of α-cells by glucose, amino acids, fatty acids and other nutrients, focusing especially on glucagon release, glucagon synthesis and α-cell survival. We have also discussed the role of glucagon in glucose homeostasis and in energy and lipid metabolism as well as its potential as a modulator of food intake and body weight. In addition to the well-established action on the liver, we discuss the effects of glucagon in other organs, where the glucagon receptor is expressed. These tissues include the heart, kidneys, adipose tissue, brain, small intestine and the gustatory epithelium. Alterations in α-cell function and abnormal glucagon concentrations are present in diabetes and are thought to aggravate the hyperglycaemic state of diabetic patients. In this respect, several experimental approaches in diabetic models have shown important beneficial results in improving hyperglycaemia after the modulation of glucagon secretion or action. Moreover, glucagon receptor agonism has also been used as a therapeutic strategy to treat obesity.
Collapse
|
46
|
Abstract
Zinc (Zn2+) is an essential element crucial for growth and development, and also plays a role in cell signaling for cellular processes like cell division and apoptosis. In the mammalian pancreas, Zn2+ is essential for the correct processing, storage, secretion, and action of insulin in beta (β)-cells. Insulin is stored inside secretory vesicles or granules, where two Zn2+ ions coordinate six insulin monomers to form the hexameric-structure on which maturated insulin crystals are based. The total Zn2+ content of the mammalian pancreas is among the highest in the body, and Zn2+ concentration reach millimolar levels in the interior of the dense-core granule. Changes in Zn2+ levels in the pancreas have been found to be associated with diabetes. Hence, the relationship between co-stored Zn2+ and insulin undoubtedly is critical to normal β-cell function. The advances in the field of Zn2+ biology over the last decade have facilitated our understanding of Zn2+ trafficking, its intracellular distribution and its storage. When exocytosis of insulin occurs, insulin granules fuse with the β-cell plasma membrane and release their contents, i.e., insulin as well as substantial amount of free Zn2+, into the extracellular space and the local circulation. Studies increasingly indicate that secreted Zn2+ has autocrine or paracrine signaling in β-cells or the neighboring cells. This review discusses the Zn2+ homeostasis in β-cells with emphasis on the potential signaling role of Zn2+ to islet biology.
Collapse
Affiliation(s)
- Yang V Li
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, 346 Irvine Hall, Athens, OH, 45701, USA,
| |
Collapse
|
47
|
The role of central nervous system on hypoglycemia and the feasibility of the brain theory in traditional Chinese medicine on treatment of diabetes mellitus. JOURNAL OF INTEGRATIVE MEDICINE-JIM 2014; 12:1-6. [DOI: 10.1016/s2095-4964(14)60008-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
48
|
Chan O, Sherwin R. Influence of VMH fuel sensing on hypoglycemic responses. Trends Endocrinol Metab 2013; 24:616-24. [PMID: 24063974 PMCID: PMC3909530 DOI: 10.1016/j.tem.2013.08.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/20/2013] [Accepted: 08/27/2013] [Indexed: 12/12/2022]
Abstract
Hypoglycemia produces complex neural and hormonal responses that restore glucose levels to normal. Glucose, metabolic substrates and their transporters, neuropeptides and neurotransmitters alter the firing rate of glucose-sensing neurons in the ventromedial hypothalamus (VMH); these monitor energy status and regulate the release of neurotransmitters that instigate a suitable counter-regulatory response. Under normal physiological conditions, these mechanisms maintain blood glucose concentrations within narrow margins. However, antecedent hypoglycemia and diabetes can lead to adaptations within the brain that impair counter-regulatory responses. Clearly, the mechanisms employed to detect and regulate the response to hypoglycemia, and the pathophysiology of defective counter-regulation in diabetes, are complex and need to be elucidated to permit the development of therapies that prevent or reduce the risk of hypoglycemia.
Collapse
Affiliation(s)
- Owen Chan
- Yale University School of Medicine, Department of Internal Medicine - Section of Endocrinology, New Haven, CT, 06520 U.S.A
| | - Robert Sherwin
- Yale University School of Medicine, Department of Internal Medicine - Section of Endocrinology, New Haven, CT, 06520 U.S.A
| |
Collapse
|
49
|
Ruz M, Carrasco F, Rojas P, Codoceo J, Inostroza J, Basfi-fer K, Valencia A, Vásquez K, Galgani J, Pérez A, López G, Arredondo M, Perez-Bravo F. Zinc as a potential coadjuvant in therapy for type 2 diabetes. Food Nutr Bull 2013; 34:215-21. [PMID: 23964394 DOI: 10.1177/156482651303400210] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Type 2 diabetes is highly prevalent in populations having high rates of overweight and obesity. It is a chronic condition responsible for long-term severe dysfunction of several organs, including the kidneys, heart, blood vessels, and eyes. Although there are a number of pharmacologic products in the market to treat insulin resistance and impaired insulin secretion--the most prominent features of this disease--interventions directed at preserving the integrity and function of beta-cells in the long term are less available. The use of some nutrients with important cellular protective roles that may lead to a preservation of beta-cells has not been fully tested; among these, zinc may be an interesting candidate. OBJECTIVE To assess the potential of zinc supplementation as coadjuvant to diabetes therapy. METHODS This article reviews the available information on the use of zinc as part of diabetes therapy. RESULTS Cellular and animal models provide information on the insulin mimetic action of zinc, as well as its role as a regulator of oxidative stress, inflammation, apoptosis, and insulin secretion. Zinc supplementation studies in humans are limited, although some positive effects have been reported; mainly, a modest but significant reduction in fasting glucose and a trend to decreased glycated hemoglobin (HbA1c). CONCLUSIONS Zinc supplementation may have beneficial effects on glycemic control. Nevertheless, among the studies considered, the vast majority lasted for 6 months or less, suggesting the importance of conducting long-duration studies given the characteristics of type 2 diabetes as a chronic disease.
Collapse
Affiliation(s)
- Manuel Ruz
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Correo 7, Santiago, Chile.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Slepchenko KG, James CBL, Li YV. Inhibitory effect of zinc on glucose-stimulated zinc/insulin secretion in an insulin-secreting β-cell line. Exp Physiol 2013; 98:1301-11. [PMID: 23603373 DOI: 10.1113/expphysiol.2013.072348] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Diminished or inappropriate secretion of insulin is associated with type II diabetes. The cellular/molecular mechanism coupled with the regulation of insulin secretion is still under intense investigation. Divalent ion zinc (Zn(2+)) is co-packaged and co-secreted with insulin and is intimately involved in the process of insulin biosynthesis and the maturation of insulin secretory granules. The study reported here investigated glucose-stimulated zinc secretion (GSZS) and the effect of zinc on glucose-stimulated insulin secretion (GSIS) in the HIT-T15 pancreatic β-cell line. Zinc secretion was measured using a newly developed fluorescent zinc imaging approach, and the insulin secretion was measured using an enzyme-linked immunosorbent assay. There was apparent granular-like zinc staining in β-cells. The application of glucose induced detectable zinc secretion or GSZS. Like GSIS, GSZS was dependent on the glucose concentration (5-20 mm) and the presence of extracellular calcium. The application of a zinc chelator enhanced GSZS. When brief paired-pulse glucose stimulations, which involve the initial glucose stimulation followed by a second round of glucose stimulation, were applied, zinc secretion or GSZS that followed the first pulse was inhibited. This inhibition was reversed by zinc chelation, suggesting a feedback mechanism on GSZS by zinc secreted from β-cells. Finally, the application of zinc (50 μm) strongly inhibited GSIS as measured by enzyme-linked immunosorbent assay. The present study suggests that insulin secretion is regulated by co-secreted zinc that may act as an autocrine inhibitory modulator.
Collapse
Affiliation(s)
- Kira G Slepchenko
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, OH 45701, USA
| | | | | |
Collapse
|