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Rix I, Lund AB, Garvey LF, Hansen CP, Chabanova E, Hartmann B, Holst JJ, Vilsbøll T, Van Hall G, Knop FK. Increased hepatic glucagon sensitivity in totally pancreatectomised patients. Eur J Endocrinol 2024; 190:446-457. [PMID: 38781444 DOI: 10.1093/ejendo/lvae054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 04/02/2024] [Accepted: 05/22/2024] [Indexed: 05/25/2024]
Abstract
OBJECTIVE The metabolic phenotype of totally pancreatectomised patients includes hyperaminoacidaemia and predisposition to hypoglycaemia and hepatic lipid accumulation. We aimed to investigate whether the loss of pancreatic glucagon may be responsible for these changes. METHODS Nine middle-aged, normal-weight totally pancreatectomised patients, nine patients with type 1 diabetes (C-peptide negative), and nine matched controls underwent two separate experimental days, each involving a 150-min intravenous infusion of glucagon (4 ng/kg/min) or placebo (saline) under fasting conditions while any basal insulin treatment was continued. RESULTS Glucagon infusion increased plasma glucagon to similar high physiological levels in all groups. The infusion increased hepatic glucose production and decreased plasma concentration of most amino acids in all groups, with more pronounced effects in the totally pancreatectomised patients compared with the other groups. Glucagon infusion diminished fatty acid re-esterification and tended to decrease plasma concentrations of fatty acids in the totally pancreatectomised patients but not in the type 1 diabetes patients. CONCLUSION Totally pancreatectomised patients were characterised by increased sensitivity to exogenous glucagon at the level of hepatic glucose, amino acid, and lipid metabolism, suggesting that the metabolic disturbances characterising these patients may be rooted in perturbed hepatic processes normally controlled by pancreatic glucagon.
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Affiliation(s)
- Iben Rix
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, 2900 Hellerup, Denmark
- Medical & Science, Zealand Pharma A/S, 2860 Søborg, Denmark
| | - Asger B Lund
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, 2900 Hellerup, Denmark
- Clinical Research, Steno Diabetes Center Copenhagen, 2730 Herlev, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Lars F Garvey
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, 2900 Hellerup, Denmark
| | - Carsten P Hansen
- Department of Surgery, Copenhagen University Hospital - Rigshospitalet, 2100 Copenhagen, Denmark
| | - Elizaveta Chabanova
- Department of Radiology, Copenhagen University Hospital - Herlev and Gentofte, 2730 Herlev, Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Tina Vilsbøll
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, 2900 Hellerup, Denmark
- Clinical Research, Steno Diabetes Center Copenhagen, 2730 Herlev, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Gerrit Van Hall
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Clinical Metabolomics Core Facility, Department of Clinical Biochemistry, Copenhagen University Hospital - Rigshospitalet, 2100 Copenhagen, Denmark
| | - Filip K Knop
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, 2900 Hellerup, Denmark
- Clinical Research, Steno Diabetes Center Copenhagen, 2730 Herlev, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
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2
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Jarak I, Barosa C, Martins FO, Silva JCP, Santos C, Belew GD, Rito J, Viegas I, Teixeira J, Oliveira PJ, Jones JG. Sources of hepatic glycogen synthesis in mice fed with glucose or fructose as the sole dietary carbohydrate. Magn Reson Med 2018; 81:639-644. [PMID: 30058123 DOI: 10.1002/mrm.27378] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/16/2018] [Accepted: 05/05/2018] [Indexed: 11/07/2022]
Abstract
PURPOSE The positional analysis of hepatic glycogen enrichment from deuterated water (2 H2 O) by 2 H NMR has been applied previously to resolve the contributions of glucose and fructose to glycogen synthesis in rodents fed a high sucrose diet. To further validate this method, this analysis was applied to mice fed with synthetic diets whose carbohydrate components consisted solely of either glucose or fructose. METHODS Eight glucose-fed and 12 fructose-fed mice were given 2 H2 O followed by ad libitum feeding overnight. Mice were then euthanized, hepatic glycogen was isolated and derivatized to monoacetone glucose, and 2 H-enrichment of positions 2, 5, and 6S were measured by 2 H NMR. From these data, the fraction of overnight glycogen appearance from the direct pathway and/or glycogen cycling and indirect pathway were estimated. Indirect pathway fractions were resolved into Krebs cycle and triose-phosphate sources-the latter including contributions from fructose metabolism. RESULTS After overnight feeding, the fraction of overnight glycogen appearance derived from direct pathway and/or glycogen cycling in glucose-fed-mice was 63 ± 1%. For the indirect pathway, Krebs cycle and triose-phosphate sources contributed 22 ± 1% and 15 ± 1%, respectively. For fructose-fed-mice, glycogen appearance was dominated by triose-phosphate sources (60 ± 2%) with lesser contributions from Krebs cycle (14 ± 1%) and direct and/or glycogen cycling (26 ± 2%). CONCLUSIONS 2 H NMR analysis of hepatic glycogen 2 H enrichment from 2 H2 O provides realistic profiles of dietary glucose and fructose contributions to hepatic glycogen synthesis in mice fed with diets containing 1 or the other sugar as the sole carbohydrate source.
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Affiliation(s)
- Ivana Jarak
- Center for Functional Ecology, Department of Life Sciences, University of Coimbra, Portugal
| | - Cristina Barosa
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - Fatima O Martins
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - Joao C P Silva
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - Cristiano Santos
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - Getachew Debas Belew
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - Joao Rito
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - Ivan Viegas
- Center for Functional Ecology, Department of Life Sciences, University of Coimbra, Portugal.,Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - Jose Teixeira
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - Paulo J Oliveira
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal
| | - John G Jones
- Center for Neurosciences and Cell Biology, UC-Biotech, University of Coimbra, Portugal.,Portuguese Diabetes Association, Lisbon, Portugal
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3
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Nielsen MF, Roelsgaard K, Keiding S, Brodersen K, Møller N, Vyberg M, Vilstrup H. Impaired hepatic counterregulatory response to insulin-induced hypoglycemia in hepatic denervated pigs. JOURNAL OF CLINICAL AND TRANSLATIONAL ENDOCRINOLOGY 2015; 2:131-136. [PMID: 29159118 PMCID: PMC5685012 DOI: 10.1016/j.jcte.2015.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 07/30/2015] [Accepted: 08/26/2015] [Indexed: 11/30/2022]
Abstract
Hepatic denervation results in a blunted counterregulatory response during insulin-induced hypoglycemia. Fasting glucose concentration, glucose production and uptake are unaffected by hepatic denervation. Insulin action and extrahepatic glucose uptake are unaffected by hepatic denervation.
Objective The liver reacts to hypoglycemia by increasing its glucose output. This response is assumed to depend both on glucose sensing at the liver and the brain, as well as efferent impulses from the brain to the liver. We tested the importance of this signaling pathway by studying the hepatic response to insulin-induced hypoglycemia in hepatic complete denervated pigs. Materials/methods Two weeks prior to the metabolic study, 36-kg pigs underwent either total hepatic denervation (DN; n = 12) or sham operation (sham; n = 12). On the metabolic study day, measurements were performed at baseline conditions and during a hypoglycemic hyperinsulinemic (5 mU/kg/min) clamp. Endogenous insulin and glucagon secretions were inhibited by somatostatin, and glucagon was replaced at baseline levels. Endogenous glucose production (EGP) and glucose utilization (Rd) were determined by [3-3H] glucose infusion. Results Baseline plasma concentrations of glucose, insulin, EGP and Rd did not differ significantly between the two groups of animals. During insulin infusion, the plasma glucose concentration was clamped at ~3 mmol/L in both groups of animals resulting in an increase in plasma concentrations of epinephrine and norepinephrine in sham pigs (both P < 0.05), while this effect was abolished in DN pigs. While insulin action (P = 0.09) and glucose utilization (P = 0.44) were similar, EGP was markedly decreased in the DN pigs (P < 0.05). Conclusion The findings indicate a blunted hepatic counterregulatory response to hypoglycemia following complete hepatic denervation. This implies that intact neural impulses to and from the liver are necessary to maintain the increase in EGP that protects the organism against hypoglycemia.
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Affiliation(s)
- Michael Festersen Nielsen
- Department of Surgery, Viborg General Hospital, Denmark.,Departments of Hepatology and Gastroenterology, Aarhus University Hospital, Denmark
| | - Klaus Roelsgaard
- Department of Medicine, Randers General Hospital, Denmark.,Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Denmark
| | - Susanne Keiding
- Departments of Hepatology and Gastroenterology, Aarhus University Hospital, Denmark.,Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Denmark
| | | | - Niels Møller
- Department of Medicine M (Endocrinology and Internal Medicine), Aarhus University Hospital, Denmark
| | - Mogens Vyberg
- Department of Pathology, Aalborg University Hospital, Denmark
| | - Hendrik Vilstrup
- Departments of Hepatology and Gastroenterology, Aarhus University Hospital, Denmark
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4
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Hinshaw L, Mallad A, Dalla Man C, Basu R, Cobelli C, Carter RE, Kudva YC, Basu A. Glucagon sensitivity and clearance in type 1 diabetes: insights from in vivo and in silico experiments. Am J Physiol Endocrinol Metab 2015; 309:E474-86. [PMID: 26152766 PMCID: PMC4556882 DOI: 10.1152/ajpendo.00236.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 06/29/2015] [Indexed: 11/22/2022]
Abstract
Glucagon use in artificial pancreas for type 1 diabetes (T1D) is being explored for prevention and rescue from hypoglycemia. However, the relationship between glucagon stimulation of endogenous glucose production (EGP) viz., hepatic glucagon sensitivity, and prevailing glucose concentrations has not been examined. To test the hypothesis that glucagon sensitivity is increased at hypoglycemia vs. euglycemia, we studied 29 subjects with T1D randomized to a hypoglycemia or euglycemia clamp. Each subject was studied at three glucagon doses at euglycemia or hypoglycemia, with EGP measured by isotope dilution technique. The peak EGP increments and the integrated EGP response increased with increasing glucagon dose during euglycemia and hypoglycemia. However, the difference in dose response based on glycemia was not significant despite higher catecholamine concentrations in the hypoglycemia group. Knowledge of glucagon's effects on EGP was used to develop an in silico glucagon action model. The model-derived output fitted the obtained data at both euglycemia and hypoglycemia for all glucagon doses tested. Glucagon clearance did not differ between glucagon doses studied in both groups. Therefore, the glucagon controller of a dual hormone control system may not need to adjust glucagon sensitivity, and hence glucagon dosing, based on glucose concentrations during euglycemia and hypoglycemia.
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Affiliation(s)
- Ling Hinshaw
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota
| | - Ashwini Mallad
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padua, Italy
| | - Rita Basu
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota;
| | - Claudio Cobelli
- Department of Information Engineering, University of Padova, Padua, Italy
| | - Rickey E Carter
- Department of Health Sciences Research, Mayo College of Medicine, Rochester, Minnesota; and
| | - Yogish C Kudva
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota
| | - Ananda Basu
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota
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5
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Abstract
Type 2 diabetes (T2D) has been known as 'bi-hormonal disorder' since decades ago, the role of glucagon from α-cell has languished whereas β-cell taking center stage. Recently, numerous findings indicate that the defects of glucagon secretion get involve with development and exacerbation of hyperglycemia in T2D. Aberrant α-cell responses exhibit both fasting and postprandial states: hyperglucagonemia contributes to fasting hyperglycemia caused by inappropriate hepatic glucose production, and to postprandial hyperglycemia owing to blunted α-cell suppression. During hypoglycemia, insufficient counter-regulation response is also observed in advanced T2D. Though many debates still remained for exact mechanisms behind the dysregulation of α-cell in T2D, it is clear that the blockade of glucagon receptor or suppression of glucagon secretion from α-cell would be novel therapeutic targets for control of hyperglycemia. Whereas there have not been remarkable advances in developing new class of drugs, currently available glucagon-like peptide-1 and dipeptidyl peptidase-IV inhibitors could be options for treatment of hyperglucagonemia. In this review, we focus on α-cell dysfunction and therapeutic potentials of targeting α-cell in T2D.
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Affiliation(s)
- Jun Sung Moon
- Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Korea
| | - Kyu Chang Won
- Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Korea
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6
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He L, Cao J, Meng S, Ma A, Radovick S, Wondisford FE. Activation of basal gluconeogenesis by coactivator p300 maintains hepatic glycogen storage. Mol Endocrinol 2013; 27:1322-32. [PMID: 23770612 DOI: 10.1210/me.2012-1413] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Because hepatic glycogenolysis maintains euglycemia during early fasting, proper hepatic glycogen synthesis in the fed/postprandial states is critical. It has been known for decades that gluconeogenesis is essential for hepatic glycogen synthesis; however, the molecular mechanism remains unknown. In this report, we show that depletion of hepatic p300 reduces glycogen synthesis, decreases hepatic glycogen storage, and leads to relative hypoglycemia. We previously reported that insulin suppressed gluconeogenesis by phosphorylating cAMP response element binding protein-binding protein (CBP) at S436 and disassembling the cAMP response element-binding protein-CBP complex. However, p300, which is closely related to CBP, lacks the corresponding S436 phosphorylation site found on CBP. In a phosphorylation-competent p300G422S knock-in mouse model, we found that mutant mice exhibited reduced hepatic glycogen content and produced significantly less glycogen in a tracer incorporation assay in the postprandial state. Our study demonstrates the important and unique role of p300 in glycogen synthesis through maintaining basal gluconeogenesis.
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Affiliation(s)
- Ling He
- Division of Metabolism, Departments of Pediatrics, Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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7
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Unger RH, Cherrington AD. Glucagonocentric restructuring of diabetes: a pathophysiologic and therapeutic makeover. J Clin Invest 2012; 122:4-12. [PMID: 22214853 DOI: 10.1172/jci60016] [Citation(s) in RCA: 497] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The hormone glucagon has long been dismissed as a minor contributor to metabolic disease. Here we propose that glucagon excess, rather than insulin deficiency, is the sine qua non of diabetes. We base this on the following evidence: (a) glucagon increases hepatic glucose and ketone production, catabolic features present in insulin deficiency; (b) hyperglucagonemia is present in every form of poorly controlled diabetes; (c) the glucagon suppressors leptin and somatostatin suppress all catabolic manifestations of diabetes during total insulin deficiency; (d) total β cell destruction in glucagon receptor-null mice does not cause diabetes; and (e) perfusion of normal pancreas with anti-insulin serum causes marked hyperglucagonemia. From this and other evidence, we conclude that glucose-responsive β cells normally regulate juxtaposed α cells and that without intraislet insulin, unregulated α cells hypersecrete glucagon, which directly causes the symptoms of diabetes. This indicates that glucagon suppression or inactivation may provide therapeutic advantages over insulin monotherapy.
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Affiliation(s)
- Roger H Unger
- Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8854, USA.
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8
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Uranga RM, Bruce-Keller AJ, Morrison CD, Fernandez-Kim SO, Ebenezer PJ, Zhang L, Dasuri K, Keller JN. Intersection between metabolic dysfunction, high fat diet consumption, and brain aging. J Neurochem 2010; 114:344-61. [PMID: 20477933 PMCID: PMC2910139 DOI: 10.1111/j.1471-4159.2010.06803.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Deleterious neurochemical, structural, and behavioral alterations are a seemingly unavoidable aspect of brain aging. However, the basis for these alterations, as well as the basis for the tremendous variability in regards to the degree to which these aspects are altered in aging individuals, remains to be elucidated. An increasing number of individuals regularly consume a diet high in fat, with high-fat diet consumption known to be sufficient to promote metabolic dysfunction, although the links between high-fat diet consumption and aging are only now beginning to be elucidated. In this review we discuss the potential role for age-related metabolic disturbances serving as an important basis for deleterious perturbations in the aging brain. These data not only have important implications for understanding the basis of brain aging, but also may be important to the development of therapeutic interventions which promote successful brain aging.
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Affiliation(s)
- Romina M. Uranga
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
| | | | - Christopher D. Morrison
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Sun Ok Fernandez-Kim
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Philip J. Ebenezer
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Le Zhang
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Kalavathi Dasuri
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Jeffrey N. Keller
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
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9
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Kreier F, Kap YS, Mettenleiter TC, van Heijningen C, van der Vliet J, Kalsbeek A, Sauerwein HP, Fliers E, Romijn JA, Buijs RM. Tracing from fat tissue, liver, and pancreas: a neuroanatomical framework for the role of the brain in type 2 diabetes. Endocrinology 2006; 147:1140-7. [PMID: 16339209 DOI: 10.1210/en.2005-0667] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The hypothalamus uses hormones and the autonomic nervous system to balance energy fluxes in the body. Here we show that the autonomic nervous system has a distinct organization in different body compartments. The same neurons control intraabdominal organs (intraabdominal fat, liver, and pancreas), whereas sc adipose tissue located outside the abdominal compartment receives input from another set of autonomic neurons. This differentiation persists up to preautonomic neurons in the hypothalamus, including the biological clock, that have a distinct organization depending on the body compartment they command. Moreover, we demonstrate a neuronal feedback from adipose tissue that reaches the brainstem. We propose that this compartment-specific organization offers a neuroanatomical perspective for the regional malfunction of organs in type 2 diabetes, where increased insulin secretion by the pancreas and disturbed glucose metabolism in the liver coincide with an augmented metabolic activity of visceral compared with sc adipose tissue.
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Affiliation(s)
- Felix Kreier
- Netherlands Institute for Brain Research, Meibergdreef 33, 1105 AZ Amsterdam, The Netherlands.
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10
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Basu A, Shah P, Nielsen M, Basu R, Rizza RA. Effects of Type 2 Diabetes on the Regulation of Hepatic Glucose Metabolism. J Investig Med 2004. [DOI: 10.1177/108155890405200630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Glucose production is inappropriately increased in people with type 2 diabetes both before and after food ingestion. Excessive postprandial glucose production occurs in the presence of decreased and delayed insulin secretion and lack of suppression of glucagon release. These abnormalities in hormone secretion, coupled with impaired insulin-induced suppression of glucose production and stimulation of splanchnic glucose uptake, likely account in large part for the excessive amounts of glucose that reach the systemic circulation for disposal by peripheral tissues following food ingestion. In contrast, when adequate basal insulin concentrations are present, neither glucagon-induced stimulation of glucose production nor glucose-induced suppression of glucose production differs in diabetic and nondiabetic subjects matched for gender, age, and degree of obesity. However, when insulin secretion is defective, lack of suppression of glucagon can cause substantial hyperglycemia by enhancing rates of glucose production. Therefore, normalization of hepatic glucose metabolism in people with type 2 diabetes mellitus likely will require normalization of insulin and glucagon secretion as well as hepatic insulin action.
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Affiliation(s)
- Ananda Basu
- Department of Endocrinology, Mayo Clinic and Foundation, Rochester, MN
| | - Pankaj Shah
- Department of Endocrinology, Mayo Clinic and Foundation, Rochester, MN
| | - Michael Nielsen
- Department of Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Rita Basu
- Department of Endocrinology, Mayo Clinic and Foundation, Rochester, MN
| | - Robert A. Rizza
- Department of Endocrinology, Mayo Clinic and Foundation, Rochester, MN
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11
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Boden G, Cheung P, Stein TP, Kresge K, Mozzoli M. FFA cause hepatic insulin resistance by inhibiting insulin suppression of glycogenolysis. Am J Physiol Endocrinol Metab 2002; 283:E12-9. [PMID: 12067837 DOI: 10.1152/ajpendo.00429.2001] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Free fatty acids (FFA) have been shown to inhibit insulin suppression of endogenous glucose production (EGP). To determine whether this is the result of stimulation by FFA of gluconeogenesis (GNG) or glycogenolysis (GL) or a combination of both, we have determined rates of GNG and GL (with (2)H(2)O) and EGP in 16 healthy nondiabetic volunteers (11 males, 5 females) during euglycemic-hyperinsulinemic (~450 pM) clamping performed either with or without simultaneous intravenous infusion of lipid plus heparin. During insulin infusion, FFA decreased from 571 to 30 micromol/l (P < 0.001), EGP from 15.7 to 2.0 micromol x kg(-1) x min(-1) (P < 0.01), GNG from 8.2 to 3.7 micromol x kg(-1). min(-1) (P < 0.05), and GL from 7.4 to -1.7 micromol x kg(-1). min(-1) (P < 0.02). During insulin plus lipid/heparin infusion, FFA increased from 499 to 1,247 micromol/l (P < 0.001). EGP decreased 64% less than during insulin alone (-5.1 +/- 0.7 vs. -13.7 +/- 3.4 micromol x kg(-1). min(-1)). The decrease in GNG was not significantly different from the decrease of GNG during insulin alone (-2.6 vs. -4.5 micromol x kg(-1). min(-1), not significant). In contrast, GL decreased 66% less than during insulin alone (-3.1 vs. -9.2 micromol x kg(-1). min(-1), P < 0.05). We conclude that insulin suppressed EGP by inhibiting GL more than GNG and that elevated plasma FFA levels attenuated the suppression of EGP by interfering with insulin suppression of GL.
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Affiliation(s)
- Guenther Boden
- Division of Endocrinology/Diabetes/Metabolism and the General Clinical Research Center, Temple University Health Sciences Center, Philadelphia, Pennsylvania 19140, USA.
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12
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Keembiyehetty CN, Candelaria RP, Majumdar G, Raghow R, Martinez-Hernandez A, Solomon SS. Paradoxical regulation of Sp1 transcription factor by glucagon. Endocrinology 2002; 143:1512-20. [PMID: 11897710 DOI: 10.1210/endo.143.4.8756] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Insulin is a potent regulator of Sp1 transcription factor. To examine if glucagon, which usually antagonizes insulin, regulates Sp1, we assessed the levels of Sp1 by Western blotting from H-411E cells exposed to glucagon with or without insulin. Glucagon alone (1.5 x 10(-9) to 1.5 x 10(-5) M) stimulated Sp1 accumulation but inhibited insulin's (10,000 microU/ml) stimulatory effect on Sp1. We also assessed the effect of TNF-alpha, wortmannin, a PI3K inhibitor, and cAMP-dependent protein kinase inhibitor on Sp1 accumulation. While TNF-alpha (5 ng/ml) blocked insulin-stimulated Sp1, it failed to block stimulation of Sp1 by glucagon (1.5 x 10(-5) M). Similarly, wortmannin inhibited insulin- but not glucagon-stimulated Sp1, whereas protein kinase inhibitor had an opposite effect. Thus, insulin acts primarily via PI3K, and glucagon apparently stimulates through a cAMP-dependent pathway. Insulin increased the staining intensity of Sp1 seen exclusively in the nuclei of H-411E cells. Sp1 was demonstrable in both nucleus and cytoplasm after glucagon treatment. Finally, as judged by immunoblotting to specific antibody, insulin but not glucagon, stimulated O-glycosylation of Sp1. Thus, unique signaling mechanisms mediate the response of Sp1 to glucagon in the presence or absence of insulin.
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Affiliation(s)
- Chithra N Keembiyehetty
- Veterans Affairs Medical Center, Research Services, University of Tennessee Health Science Center, Memphis, Tennessee 38104, USA
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13
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Shah P, Basu A, Basu R, Rizza R. Impact of lack of suppression of glucagon on glucose tolerance in humans. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E283-90. [PMID: 10444424 DOI: 10.1152/ajpendo.1999.277.2.e283] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
People with type 2 diabetes have defects in both alpha- and beta-cell function. To determine whether lack of suppression of glucagon causes hyperglycemia when insulin secretion is impaired but not when insulin secretion is intact, twenty nondiabetic subjects were studied on two occasions. On both occasions, a "prandial" glucose infusion was given over 5 h while endogenous hormone secretion was inhibited. Insulin was infused so as to mimic either a nondiabetic (n = 10) or diabetic (n = 10) postprandial profile. Glucagon was infused at a rate of 1.25 ng. kg(-1). min(-1), beginning either at time zero to prevent a fall in glucagon (nonsuppressed study day) or at 2 h to create a transient fall in glucagon (suppressed study day). During the "diabetic" insulin profile, lack of glucagon suppression resulted in a marked increase (P < 0.002) in both the peak glucose concentration (11.9 +/- 0.4 vs. 8.9 +/- 0.4 mmol/l) and the area above basal of glucose (927 +/- 77 vs. 546 +/- 112 mmol. l(-1). 6 h) because of impaired (P < 0.001) suppression of glucose production. In contrast, during the "nondiabetic" insulin profile, lack of suppression of glucagon resulted in only a slight increase (P < 0.02) in the peak glucose concentration (9.1 +/- 0.4 vs. 8.4 +/- 0.3 mmol/l) and the area above basal of glucose (654 +/- 146 vs. 488 +/- 118 mmol. l(-1). 6 h). Of interest, when glucagon was suppressed, glucose concentrations differed only minimally during the nondiabetic and diabetic insulin profiles. These data indicate that lack of suppression of glucagon can cause substantial hyperglycemia when insulin availability is limited, therefore implying that inhibitors of glucagon secretion and/or glucagon action are likely to be useful therapeutic agents in such individuals.
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Affiliation(s)
- P Shah
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA
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