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Kikuchi O, Ikeuchi Y, Kobayashi M, Tabei Y, Yokota-Hashimoto H, Kitamura T. Imeglimin enhances glucagon secretion through an indirect mechanism and improves fatty liver in high-fat, high-sucrose diet-fed mice. J Diabetes Investig 2024. [PMID: 38874179 DOI: 10.1111/jdi.14249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/03/2024] [Accepted: 05/24/2024] [Indexed: 06/15/2024] Open
Abstract
AIMS/INTRODUCTION Imeglimin is a recently approved oral antidiabetic agent that improves insulin resistance, and promotes insulin secretion from pancreatic β-cells. Here, we investigated the effects of imeglimin on glucagon secretion from pancreatic α-cells. MATERIALS AND METHODS Experiments were carried out in high-fat, high-sucrose diet-fed mice. The effects of imeglimin were examined using insulin and glucose tolerance tests, glucose clamp studies, and measurements of glucagon secretion from isolated islets. Glucagon was measured using both the standard and the sequential protocol of Mercodia sandwich enzyme-linked immunosorbent assay; the latter eliminates cross-reactivities with other proglucagon-derived peptides. RESULTS Plasma glucagon, insulin and glucagon-like peptide-1 levels were increased by imeglimin administration in high-fat, high-sucrose diet-fed mice. Glucose clamp experiments showed that the glucagon increase was not caused by reduced blood glucose levels. After both single and long-term administration of imeglimin, glucagon secretions were significantly enhanced during glucose tolerance tests. Milder enhancement was observed when using the sequential protocol. Long-term administration of imeglimin did not alter α-cell mass. Intraperitoneal imeglimin administration did not affect glucagon secretion, despite significantly decreased blood glucose levels. Imeglimin did not enhance glucagon secretion from isolated islets. Imeglimin administration improved fatty liver by suppressing de novo lipogenesis through decreasing sterol regulatory element binding protein-1c and carbohydrate response element binding protein and their target genes, while enhancing fatty acid oxidation through increasing carnitine palmitoyltransferase I. CONCLUSIONS Overall, the present results showed that imeglimin enhances glucagon secretion through an indirect mechanism. Our findings also showed that glucagon secretion promoted by imeglimin could contribute to improvement of fatty liver through suppressing de novo lipogenesis and enhancing fatty acid oxidation.
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Affiliation(s)
- Osamu Kikuchi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
| | - Yuichi Ikeuchi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
| | - Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
| | - Yoko Tabei
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
| | - Hiromi Yokota-Hashimoto
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
| | - Tadahiro Kitamura
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
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2
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Kjeldsen SAS, Thomsen MN, Skytte MJ, Samkani A, Richter MM, Frystyk J, Magkos F, Hansen E, Thomsen HS, Holst JJ, Madsbad S, Haugaard SB, Krarup T, Wewer Albrechtsen NJ. Markers of Glucagon Resistance Improve With Reductions in Hepatic Steatosis and Body Weight in Type 2 Diabetes. J Endocr Soc 2023; 7:bvad122. [PMID: 37818402 PMCID: PMC10561012 DOI: 10.1210/jendso/bvad122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Indexed: 10/12/2023] Open
Abstract
Context Hyperglucagonemia may develop in type 2 diabetes due to obesity-prone hepatic steatosis (glucagon resistance). Markers of glucagon resistance (including the glucagon-alanine index) improve following diet-induced weight loss, but the partial contribution of lowering hepatic steatosis vs body weight is unknown. Objective This work aimed to investigate the dependency of body weight loss following a reduction in hepatic steatosis on markers of glucagon resistance in type 2 diabetes. Methods A post hoc analysis was conducted from 2 previously published randomized controlled trials. We investigated the effect of weight maintenance (study 1: isocaloric feeding) or weight loss (study 2: hypocaloric feeding), both of which induced reductions in hepatic steatosis, on markers of glucagon sensitivity, including the glucagon-alanine index measured using a validated enzyme-linked immunosorbent assay and metabolomics in 94 individuals (n = 28 in study 1; n = 66 in study 2). Individuals with overweight or obesity with type 2 diabetes were randomly assigned to a 6-week conventional diabetes (CD) or carbohydrate-reduced high-protein (CRHP) diet within both isocaloric and hypocaloric feeding-interventions. Results By design, weight loss was greater after hypocaloric compared to isocaloric feeding, but both diets caused similar reductions in hepatic steatosis, allowing us to investigate the effect of reducing hepatic steatosis with or without a clinically relevant weight loss on markers of glucagon resistance. The glucagon-alanine index improved following hypocaloric, but not isocaloric, feeding, independently of macronutrient composition. Conclusion Improvements in glucagon resistance may depend on body weight loss in patients with type 2 diabetes.
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Affiliation(s)
- Sasha A S Kjeldsen
- Department of Clinical Biochemistry, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, 2400, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, 2200, Denmark
| | - Mads N Thomsen
- Department of Endocrinology, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, 2400, Denmark
| | - Mads J Skytte
- Department of Endocrinology, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, 2400, Denmark
| | - Amirsalar Samkani
- Department of Endocrinology, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, 2400, Denmark
| | - Michael M Richter
- Department of Clinical Biochemistry, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, 2400, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, 2200, Denmark
| | - Jan Frystyk
- Department of Endocrinology, Odense University Hospital, Odense, 5000, Denmark
| | - Faidon Magkos
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Frederiksberg, 1958, Denmark
| | - Elizaveta Hansen
- Department of Radiology, Copenhagen University Hospital-Herlev, Herlev, 2730, Denmark
| | - Henrik S Thomsen
- Department of Radiology, Copenhagen University Hospital-Herlev, Herlev, 2730, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, 2200, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, 2200, Denmark
| | - Sten Madsbad
- Department of Endocrinology, Copenhagen University Hospital-Hvidovre, Hvidovre, 2650, Denmark
| | - Steen B Haugaard
- Department of Endocrinology, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, 2400, Denmark
- Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, 2200, Denmark
| | - Thure Krarup
- Department of Endocrinology, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, 2400, Denmark
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Frederiksberg, 1958, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Clinical Biochemistry, Copenhagen University Hospital-Bispebjerg and Frederiksberg, Copenhagen, 2400, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, 2200, Denmark
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3
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Holst JJ. Glucagon 100 years. Important, but still enigmatic. Peptides 2023; 161:170942. [PMID: 36626940 DOI: 10.1016/j.peptides.2023.170942] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 12/30/2022] [Accepted: 01/03/2023] [Indexed: 01/09/2023]
Abstract
Glucagon was discovered in 1923 as a contaminant of early insulin preparations, and its hormonal status was not established until its structure was established in the 1950 s and when the first radioimmunoassay was developed by Roger Unger, providing information about its secretion. Its role in hepatic glucose production was soon established and it was proposed as an essential factor in diabetic hyperglycemia. However, even today a number of issues remain unsolved. For instance, the assays for glucagon are not straightforward, although the development of sandwich ELISAs allowed reasonably accurate measurements also in rodents. The tools for evaluation of glucagon physiology include pancreatectomy, but studies in both humans and experimental animals pointed towards extrapancreatic sources of glucagon. It was demonstrated that glucagon receptor knockout animals do not develop diabetes upon destruction of their beta cells with streptozotocin. However, in patients with type 1 diabetes, glucagon antagonists do not normalize glucose levels; but antagonists do lower glucose levels in patients with in type 2 diabetes. Recent studies in animals and humans have confirmed the essential role of glucagon in glucose metabolism, but have suggested that it may be at least equally important for amino acid and lipid metabolism. In spite of the 100 years, glucagon research is very much alive.
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Affiliation(s)
- Jens Juul Holst
- NovoNordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Denmark.
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4
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Galsgaard KD, Elmelund E, Johansen CD, Bomholt AB, Kizilkaya HS, Ceutz F, Hunt JE, Kissow H, Winther-Sørensen M, Sørensen CM, Kruse T, Lau JF, Rosenkilde MM, Ørskov C, Christoffersen C, Holst JJ, Wewer Albrechtsen NJ. Glucagon receptor antagonism impairs and glucagon receptor agonism enhances triglycerides metabolism in mice. Mol Metab 2022; 66:101639. [PMID: 36400402 PMCID: PMC9706156 DOI: 10.1016/j.molmet.2022.101639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/06/2022] [Accepted: 11/09/2022] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE Treatment with glucagon receptor antagonists (GRAs) reduces blood glucose but causes dyslipidemia and accumulation of fat in the liver. We investigated the acute and chronic effects of glucagon on lipid metabolism in mice. METHODS Chronic effects of glucagon receptor signaling on lipid metabolism were studied using oral lipid tolerance tests (OLTTs) in overnight fasted glucagon receptor knockout (Gcgr-/-) mice, and in C57Bl/6JRj mice treated with a glucagon receptor antibody (GCGR Ab) or a long-acting glucagon analogue (GCGA) for eight weeks. Following treatment, liver tissue was harvested for RNA-sequencing and triglyceride measurements. Acute effects were studied in C57Bl/6JRj mice treated with a GRA or GCGA 1 h or immediately before OLTTs, respectively. Direct effects of glucagon on hepatic lipolysis were studied using isolated perfused mouse liver preparations. To investigate potential effects of GCGA and GRA on gastric emptying, paracetamol was, in separate experiments, administered immediately before OLTTs. RESULTS Plasma triglyceride concentrations increased 2-fold in Gcgr-/- mice compared to their wild-type littermates during the OLTT (P = 0.001). Chronic treatment with GCGR Ab increased, whereas GCGA treatment decreased, plasma triglyceride concentrations during OLTTs (P < 0.05). Genes involved in lipid metabolism were upregulated upon GCGR Ab treatment while GCGA treatment had opposite effects. Acute GRA and GCGA treatment, respectively, increased (P = 0.02) and decreased (P = 0.003) plasma triglyceride concentrations during OLTTs. Glucagon stimulated hepatic lipolysis, evident by an increase in free fatty acid concentrations in the effluent from perfused mouse livers. In line with this, GCGR Ab treatment increased, while GCGA treatment decreased, liver triglyceride concentrations. The effects of glucagon appeared independent of changes in gastric emptying of paracetamol. CONCLUSIONS Glucagon receptor signaling regulates triglyceride metabolism, both chronically and acutely, in mice. These data expand glucagon´s biological role and implicate that intact glucagon signaling is important for lipid metabolism. Glucagon agonism may have beneficial effects on hepatic and peripheral triglyceride metabolism.
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Affiliation(s)
- Katrine D. Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Emilie Elmelund
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christian D. Johansen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark,Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anna B. Bomholt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hüsün S. Kizilkaya
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Frederik Ceutz
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jenna E. Hunt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hannelouise Kissow
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark,Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Charlotte M. Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Kruse
- Novo Nordisk A/S, Research Chemistry, Novo Nordisk Park, DK-2760 Måløv, Denmark
| | - Jesper F. Lau
- Novo Nordisk A/S, Research Chemistry, Novo Nordisk Park, DK-2760 Måløv, Denmark
| | - Mette M. Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Cathrine Ørskov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christina Christoffersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark,Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jens J. Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J. Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark,Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark,Department of Clinical Biochemistry, Bispebjerg & Frederiksberg Hospitals, University of Copenhagen, 2400 Bispebjerg, Denmark,Corresponding author. Department of Biomedical Sciences and Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, and Department of Clinical Biochemistry, Bispebjerg & Frederiksberg Hospitals, University of Copenhagen, 2400 Bispebjerg, Denmark.
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5
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Elmelund E, Galsgaard KD, Johansen CD, Trammell SA, Bomholt AB, Winther-Sørensen M, Hunt JE, Sørensen CM, Kruse T, Lau JF, Grevengoed TJ, Holst JJ, Wewer Albrechtsen NJ. Opposing effects of chronic glucagon receptor agonism and antagonism on amino acids, hepatic gene expression, and alpha cells. iScience 2022; 25:105296. [PMID: 36325048 PMCID: PMC9618771 DOI: 10.1016/j.isci.2022.105296] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/29/2022] [Accepted: 09/30/2022] [Indexed: 01/09/2023] Open
Abstract
The pancreatic hormone, glucagon, is known to regulate hepatic glucose production, but recent studies suggest that its regulation of hepatic amino metabolism is equally important. Here, we show that chronic glucagon receptor activation with a long-acting glucagon analog increases amino acid catabolism and ureagenesis and causes alpha cell hypoplasia in female mice. Conversely, chronic glucagon receptor inhibition with a glucagon receptor antibody decreases amino acid catabolism and ureagenesis and causes alpha cell hyperplasia and beta cell loss. These effects were associated with the transcriptional regulation of hepatic genes related to amino acid uptake and catabolism and by the non-transcriptional modulation of the rate-limiting ureagenesis enzyme, carbamoyl phosphate synthetase-1. Our results support the importance of glucagon receptor signaling for amino acid homeostasis and pancreatic islet integrity in mice and provide knowledge regarding the long-term consequences of chronic glucagon receptor agonism and antagonism. Glucagon receptor agonism increases amino acid catabolism and hepatic CPS-1 activity Glucagon receptor signaling regulates the number of pancreatic alpha cells Glucagon regulates the hepatic transcription of genes involved in amino acid metabolism
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Affiliation(s)
- Emilie Elmelund
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Katrine D. Galsgaard
- 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
| | - Christian D. Johansen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Samuel A.J. Trammell
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Anna B. Bomholt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Jenna E. Hunt
- 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
| | - Charlotte M. Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Thomas Kruse
- Novo Nordisk A/S, Research Chemistry, Novo Nordisk Park, 2760 Måløv, Denmark
| | - Jesper F. Lau
- Novo Nordisk A/S, Research Chemistry, Novo Nordisk Park, 2760 Måløv, Denmark
| | - Trisha J. Grevengoed
- Department of Biomedical Sciences, 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
| | - Nicolai J. Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Department of Clinical Biochemistry, Bispebjerg & Frederiksberg Hospitals, University of Copenhagen, 2400 Bispebjerg, Denmark
- Corresponding author
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6
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Jimenez-Gonzalez M, Li R, Pomeranz LE, Alvarsson A, Marongiu R, Hampton RF, Kaplitt MG, Vasavada RC, Schwartz GJ, Stanley SA. Mapping and targeted viral activation of pancreatic nerves in mice reveal their roles in the regulation of glucose metabolism. Nat Biomed Eng 2022; 6:1298-1316. [PMID: 35835995 PMCID: PMC9669304 DOI: 10.1038/s41551-022-00909-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 06/09/2022] [Indexed: 11/09/2022]
Abstract
A lack of comprehensive mapping of ganglionic inputs into the pancreas and of technology for the modulation of the activity of specific pancreatic nerves has hindered the study of how they regulate metabolic processes. Here we show that the pancreas-innervating neurons in sympathetic, parasympathetic and sensory ganglia can be mapped in detail by using tissue clearing and retrograde tracing (the tracing of neural connections from the synapse to the cell body), and that genetic payloads can be delivered via intrapancreatic injection to target sites in efferent pancreatic nerves in live mice through optimized adeno-associated viruses and neural-tissue-specific promoters. We also show that, in male mice, the targeted activation of parasympathetic cholinergic intrapancreatic ganglia and neurons doubled plasma-insulin levels and improved glucose tolerance, and that tolerance was impaired by stimulating pancreas-projecting sympathetic neurons. The ability to map the peripheral ganglia innervating the pancreas and to deliver transgenes to specific pancreas-projecting neurons will facilitate the examination of ganglionic inputs and the study of the roles of pancreatic efferent innervation in glucose metabolism.
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Affiliation(s)
- M Jimenez-Gonzalez
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - R Li
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - L E Pomeranz
- Laboratory of Molecular Genetics, The Rockefeller University, New York, NY, USA
| | - A Alvarsson
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - R Marongiu
- Laboratory of Molecular Neurosurgery, Department of Neurological Surgery, Weill Cornell Medical College, New York, NY, USA
| | - R F Hampton
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - M G Kaplitt
- Laboratory of Molecular Neurosurgery, Department of Neurological Surgery, Weill Cornell Medical College, New York, NY, USA
| | - R C Vasavada
- Department of Translational Research and Cellular Therapeutics, City of Hope, Duarte, CA, USA
| | - G J Schwartz
- Departments of Medicine and Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - S A Stanley
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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7
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Lu B, Chen J, Xu G, Grayson TB, Jing G, Jo S, Shalev A. Alpha Cell Thioredoxin-interacting Protein Deletion Improves Diabetes-associated Hyperglycemia and Hyperglucagonemia. Endocrinology 2022; 163:bqac133. [PMID: 35957590 PMCID: PMC10233251 DOI: 10.1210/endocr/bqac133] [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: 05/28/2022] [Indexed: 11/19/2022]
Abstract
Thioredoxin-interacting protein (TXNIP) has emerged as a key factor in pancreatic beta cell biology, and its upregulation by glucose and diabetes contributes to the impairment in functional beta cell mass and glucose homeostasis. In addition, beta cell deletion of TXNIP protects against diabetes in different mouse models. However, while TXNIP is ubiquitously expressed, its role in pancreatic alpha cells has remained elusive. We generated an alpha cell TXNIP knockout (aTKO) mouse and assessed the effects on glucose homeostasis. While no significant changes were observed on regular chow, after a 30-week high-fat diet, aTKO animals showed improvement in glucose tolerance and lower blood glucose levels compared to their control littermates. Moreover, in the context of streptozotocin (STZ)-induced diabetes, aTKO mice showed significantly lower blood glucose levels compared to controls. While serum insulin levels were reduced in both control and aTKO mice, STZ-induced diabetes significantly increased glucagon levels in control mice, but this effect was blunted in aTKO mice. Moreover, glucagon secretion from aTKO islets was >2-fold lower than from control islets, while insulin secretion was unchanged in aTKO islets. At the same time, no change in alpha cell or beta cell numbers or mass was observed, and glucagon and insulin expression and content were comparable in isolated islets from aTKO and control mice. Thus together the current studies suggest that downregulation of alpha cell TXNIP is associated with reduced glucagon secretion and that this may contribute to the glucose-lowering effects observed in diabetic aTKO mice.
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Affiliation(s)
- Brian Lu
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Junqin Chen
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Guanlan Xu
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Truman B Grayson
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Gu Jing
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - SeongHo Jo
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Anath Shalev
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
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8
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Yong HJ, Toledo MP, Nowakowski RS, Wang YJ. Sex Differences in the Molecular Programs of Pancreatic Cells Contribute to the Differential Risks of Type 2 Diabetes. Endocrinology 2022; 163:bqac156. [PMID: 36130190 PMCID: PMC10409906 DOI: 10.1210/endocr/bqac156] [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: 07/26/2022] [Indexed: 11/19/2022]
Abstract
Epidemiology studies demonstrate that women are at a significantly lower risk of developing type 2 diabetes (T2D) compared to men. However, the molecular basis of this risk difference is not well understood. In this study, we examined the sex differences in the genetic programs of pancreatic endocrine cells. We combined pancreas perifusion data and single-cell genomic data from our laboratory and from publicly available data sets to investigate multiple axes of the sex differences in the human pancreas at the single-cell type and single-cell level. We systematically compared female and male islet secretion function, gene expression program, and regulatory principles of pancreatic endocrine cells. The perifusion data indicate that female endocrine cells have a higher secretion capacity than male endocrine cells. Single-cell RNA-sequencing analysis suggests that endocrine cells in male controls have molecular signatures that resemble T2D. In addition, we identified genomic elements associated with genome-wide association study T2D loci to have differential accessibility between female and male delta cells. These genomic elements may play a sex-specific causal role in the pathogenesis of T2D. We provide molecular mechanisms that explain the differential risk of T2D between women and men. Knowledge gained from our study will accelerate the development of diagnostics and therapeutics in sex-aware precision medicine for diabetes.
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Affiliation(s)
- Hyo Jeong Yong
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, USA
| | - Maria Pilar Toledo
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, USA
| | - Richard S Nowakowski
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, USA
| | - Yue J Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, USA
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9
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Maruszczak K, Rasmussen C, Ceutz FR, Ørgaard A, Elmelund E, Richter MM, Holst JJ, Winther-Sørensen M, Wewer Albrechtsen NJ. Arginine-induced glucagon secretion and glucagon-induced enhancement of amino acid catabolism are not influenced by ambient glucose levels in mice. Am J Physiol Endocrinol Metab 2022; 323:E207-E214. [PMID: 35830690 DOI: 10.1152/ajpendo.00122.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amino acids stimulate the secretion of glucagon, and glucagon receptor signaling regulates amino acid catabolism via ureagenesis, together constituting the liver-α cell axis. Impairment of the liver-α cell axis is observed in metabolic diseases such as diabetes. It is, however, unknown whether glucose affects the liver-α cell axis. We investigated the role of glucose on the liver-α cell axis in vivo and ex vivo. The isolated perfused mouse pancreas was used to evaluate the direct effect of low (3.5 mmol/L) and high (15 mmol/L) glucose levels on amino acid (10 mmol/L arginine)-induced glucagon secretion. High glucose levels alone lowered glucagon secretion, but the amino acid-induced glucagon responses were similar in high and low glucose conditions (P = 0.38). The direct effect of glucose on glucagon and amino acid-induced ureagenesis was assessed using isolated perfused mouse livers stimulated with a mixture of amino acids (VaminR, 10 mmol/L) and glucagon (10 nmol/L) during high and low glucose conditions. Urea production increased robustly but was independent of glucose levels (P = 0.95). To investigate the whole body effects of glucose on the liver-α cell axis, four groups of mice received intraperitoneal injections of glucose-Vamin (2 g/kg, + 3.5 µmol/g, respectively, G/V), saline-Vamin (S/V), glucose-saline (G/S), or saline-saline (S/S). Blood glucose did not differ significantly between G/S and G/V groups. Levels of glucagon and amino acids were similar in the G/V and S/V groups (P = 0.28). Amino acids may overrule the inhibitory effect of glucose on glucagon secretion and the liver-α cell axis may operate independently of glucose in mice.NEW & NOTEWORTHY Glucagon is an essential regulator of our metabolism. Recent evidence suggests that the physiological actions of glucagon reside in amino acid catabolism in the so-called liver-α cell axis, in which amino acids stimulate glucagon secretion and glucagon enhances hepatic amino acid catabolism. Here, it is demonstrated that this feedback system is independent of glycemia possibly explaining why hyperglycemia in diabetes may not suppress α cell secretion.
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Affiliation(s)
- Katharina Maruszczak
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
- Obesity Research Unit, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Christine Rasmussen
- Department for Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Frederik R Ceutz
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anne Ørgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Emilie Elmelund
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael M Richter
- Department for Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department for Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department for Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
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10
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Signaling pathways in obesity: mechanisms and therapeutic interventions. Signal Transduct Target Ther 2022; 7:298. [PMID: 36031641 PMCID: PMC9420733 DOI: 10.1038/s41392-022-01149-x] [Citation(s) in RCA: 84] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/26/2022] [Accepted: 08/08/2022] [Indexed: 12/19/2022] Open
Abstract
Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.
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11
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Holst JJ. Glucagon and other proglucagon-derived peptides in the pathogenesis of obesity. Front Nutr 2022; 9:964406. [PMID: 35990325 PMCID: PMC9386348 DOI: 10.3389/fnut.2022.964406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/06/2022] [Indexed: 02/04/2023] Open
Abstract
Because of differential processing of the hormone precursor, proglucagon, numerous peptide products are released from the pancreatic alpha cells and the intestinal L-cells in which the (pro)glucagon gene is expressed. Of particular interest in relation to obesity are glucagon from the pancreas and oxyntomodulin and GLP-1 from the gut, all of which inhibit food intake, but the other products are also briefly discussed, because knowledge about these is required for selection and evaluation of the methods for measurement of the hormones. The distal intestinal L-cells also secrete the appetite-inhibiting hormone PYY. Characteristics of the secretion of the pancreatic and intestinal products are described, and causes of the hypersecretion of glucagon in obesity and type 2 diabetes are discussed. In contrast, the secretion of the products of the L-cells is generally impaired in obesity, raising questions about their role in the development of obesity. It is concluded that the impairment probably is secondary to obesity, but the lower plasma levels may contribute to the development.
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Affiliation(s)
- Jens Juul Holst
- The NovoNordisk Foundation Center for Basic Metabolic Research, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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12
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Del Prato S, Gallwitz B, Holst JJ, Meier JJ. The incretin/glucagon system as a target for pharmacotherapy of obesity. Obes Rev 2022; 23:e13372. [PMID: 34713962 PMCID: PMC9286339 DOI: 10.1111/obr.13372] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 09/08/2021] [Accepted: 09/08/2021] [Indexed: 12/14/2022]
Abstract
Obesity is a chronic, multifactorial, relapsing disease. Despite multicomponent lifestyle interventions, including pharmacotherapy, maintaining bodyweight loss is challenging for many people. The pathophysiology of obesity is complex, and currently approved pharmacotherapies only target a few of the many pathways involved; thus, single-targeting agents have limited efficacy. Proglucagon-derived peptides, glucagon, and the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), represent attractive targets for managing obesity and metabolic disorders because they may have direct roles in multiple mechanisms including satiety, energy homeostasis, and lipolytic activity. Unimolecular dual and triple agonists targeting glucagon and incretin hormone receptors have been shown to promote bodyweight loss, lower glucose levels, and reduce food intake in animal models of obesity. Multiple dual receptor agonists are in clinical development for the treatment of obesity, including GLP-1/GIP and GLP-1/glucagon receptor agonists. The extent to which glucagon contributes to treatment effects remains to be understood, but it may promote bodyweight loss by reducing food intake, while concomitant GLP-1 receptor agonism ensures normal glucose control. Further research is required to fully understand the molecular mechanisms of action and metabolic effects of both dual and triple receptor agonists.
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Affiliation(s)
- Stefano Del Prato
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Baptist Gallwitz
- Department of Internal Medicine IV, Eberhard Karls University, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, University of Tübingen, Tübingen, Germany
| | - Jens Juul Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Juris J Meier
- Division of Diabetology, Katholisches Klinikum Bochum, St. Josef Hospital, Ruhr University, Bochum, Germany
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13
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Wewer Albrechtsen NJ, Kjeldsen SAS, Jensen NJ, Rungby J, Veedfald S, Bojsen-Møller KN, Dirksen C, Jensen CZ, Martinussen C, Madsbad S, Holst JJ. On measurements of glucagon secretion in healthy, obese, and Roux-en-Y gastric bypass operated individuals using sandwich ELISA. Scandinavian Journal of Clinical and Laboratory Investigation 2021; 82:75-83. [PMID: 34935574 DOI: 10.1080/00365513.2021.2016943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Glucagon is a key regulator of metabolism and is used in the diagnostic of neuroendocrine tumors. Accurate measurement of glucagon requires both extreme sensitivity and specificity since several peptides are derived from the same proglucagon precursor encoding part of the glucagon sequence and given that glucagon circulates in picomolar concentrations. A sandwich ELISA was recently developed and extensively evaluated; however, this method may not be accurate when measuring glucagon in patients with an enhanced production of proglucagon-derived peptides as seen after Roux-en-Y gastric bypass (RYGB). To overcome this, a modified version of the ELISA was developed. In this study, we evaluate an unmodified and a modified version of the ELISA in healthy individuals, individuals with obesity, and finally in two cohorts of patients following RYGB surgery using different nutrient stimuli to assess glucagon dynamics. Finally, in vitro spike-in recoveries using native glucagon and proglucagon-derived peptides were performed in buffer and in plasma. Our data support that both versions of the ELISA accurately capture endogenous and exogenous glucagon in healthy individuals and in individuals with obesity. However, the unmodified version of the assay may overestimate glucagon levels in patients following RYGB in line with minimal but consistent cross-reactivity to oxyntomodulin and glicentin that both are 50-fold increased after RYGB. Importantly, we did not find any changes between the two protocols at fasted conditions and therefore diagnostics of glucagonomas is not affected by the choice of assay procedure nor the surgical history of the patient (RYGB).
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Affiliation(s)
- Nicolai J Wewer Albrechtsen
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sasha A S Kjeldsen
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Endocrinology, Bispebjerg University Hospital, Bispebjerg, Denmark
| | - Nicole J Jensen
- Department of Endocrinology, Bispebjerg University Hospital, Bispebjerg, Denmark
| | - Jørgen Rungby
- Department of Endocrinology, Bispebjerg University Hospital, Bispebjerg, Denmark
| | - Simon Veedfald
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Carsten Dirksen
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
| | | | | | - Sten Madsbad
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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14
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Kjeldsen SAS, Hansen LH, Esser N, Mongovin S, Winther-Sørensen M, Galsgaard KD, Hunt JE, Kissow H, Ceutz FR, Terzic D, Mark PD, Plomgaard P, Goetze JP, Goossens GH, Blaak EE, Deacon CF, Rosenkilde MM, Zraika S, Holst JJ, Wewer Albrechtsen NJ. Neprilysin Inhibition Increases Glucagon Levels in Humans and Mice With Potential Effects on Amino Acid Metabolism. J Endocr Soc 2021; 5:bvab084. [PMID: 34337276 PMCID: PMC8317634 DOI: 10.1210/jendso/bvab084] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Indexed: 01/12/2023] Open
Abstract
Context Inhibitors of the protease neprilysin (NEP) are used for treating heart failure, but are also linked to improvements in metabolism. NEP may cleave proglucagon-derived peptides, including the glucose and amino acid (AA)-regulating hormone glucagon. Studies investigating NEP inhibition on glucagon metabolism are warranted. Objective This work aims to investigate whether NEP inhibition increases glucagon levels. Methods Plasma concentrations of glucagon and AAs were measured in eight healthy men during a mixed meal with and without a single dose of the NEP inhibitor/angiotensin II type 1 receptor antagonist, sacubitril/valsartan (194 mg/206 mg). Long-term effects of sacubitril/valsartan (8 weeks) were investigated in individuals with obesity (n = 7). Mass spectrometry was used to investigate NEP-induced glucagon degradation, and the derived glucagon fragments were tested pharmacologically in cells transfected with the glucagon receptor (GCGR). Genetic deletion or pharmacological inhibition of NEP with or without concomitant GCGR antagonism was tested in mice to evaluate effects on AA metabolism. Results In healthy men, a single dose of sacubitril/valsartan significantly increased postprandial concentrations of glucagon by 228%, concomitantly lowering concentrations of AAs including glucagonotropic AAs. Eight-week sacubitril/valsartan treatment increased fasting glucagon concentrations in individuals with obesity. NEP cleaved glucagon into 5 inactive fragments (in vitro). Pharmacological NEP inhibition protected both exogenous and endogenous glucagon in mice after an AA challenge, while NEP-deficient mice showed elevated fasting and AA-stimulated plasma concentrations of glucagon and urea compared to controls. Conclusion NEP cleaves glucagon, and inhibitors of NEP result in hyperglucagonemia and may increase postprandial AA catabolism without affecting glycemia.
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Affiliation(s)
- Sasha A S Kjeldsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark
| | - Lasse H Hansen
- Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark.,Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Nathalie Esser
- Department of Medicine, Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, Washington 98195-6426, USA.,Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA
| | - Steve Mongovin
- Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark
| | - Katrine D Galsgaard
- 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
| | - Jenna E Hunt
- 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
| | - Hannelouise Kissow
- 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
| | - Frederik R Ceutz
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark
| | - Dijana Terzic
- Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Peter D Mark
- Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Peter Plomgaard
- Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Jens P Goetze
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Gijs H Goossens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Ellen E Blaak
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Carolyn F Deacon
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark
| | - Mette M Rosenkilde
- 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
| | - Sakeneh Zraika
- Department of Medicine, Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, Washington 98195-6426, USA.,Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
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15
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Winther-Sørensen M, Galsgaard KD, Santos A, Trammell SAJ, Sulek K, Kuhre RE, Pedersen J, Andersen DB, Hassing AS, Dall M, Treebak JT, Gillum MP, Torekov SS, Windeløv JA, Hunt JE, Kjeldsen SAS, Jepsen SL, Vasilopoulou CG, Knop FK, Ørskov C, Werge MP, Bisgaard HC, Eriksen PL, Vilstrup H, Gluud LL, Holst JJ, Wewer Albrechtsen NJ. Glucagon acutely regulates hepatic amino acid catabolism and the effect may be disturbed by steatosis. Mol Metab 2020; 42:101080. [PMID: 32937194 PMCID: PMC7560169 DOI: 10.1016/j.molmet.2020.101080] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/28/2020] [Accepted: 09/09/2020] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE Glucagon is well known to regulate blood glucose but may be equally important for amino acid metabolism. Plasma levels of amino acids are regulated by glucagon-dependent mechanism(s), while amino acids stimulate glucagon secretion from alpha cells, completing the recently described liver-alpha cell axis. The mechanisms underlying the cycle and the possible impact of hepatic steatosis are unclear. METHODS We assessed amino acid clearance in vivo in mice treated with a glucagon receptor antagonist (GRA), transgenic mice with 95% reduction in alpha cells, and mice with hepatic steatosis. In addition, we evaluated urea formation in primary hepatocytes from ob/ob mice and humans, and we studied acute metabolic effects of glucagon in perfused rat livers. We also performed RNA sequencing on livers from glucagon receptor knock-out mice and mice with hepatic steatosis. Finally, we measured individual plasma amino acids and glucagon in healthy controls and in two independent cohorts of patients with biopsy-verified non-alcoholic fatty liver disease (NAFLD). RESULTS Amino acid clearance was reduced in mice treated with GRA and mice lacking endogenous glucagon (loss of alpha cells) concomitantly with reduced production of urea. Glucagon administration markedly changed the secretion of rat liver metabolites and within minutes increased urea formation in mice, in perfused rat liver, and in primary human hepatocytes. Transcriptomic analyses revealed that three genes responsible for amino acid catabolism (Cps1, Slc7a2, and Slc38a2) were downregulated both in mice with hepatic steatosis and in mice with deletion of the glucagon receptor. Cultured ob/ob hepatocytes produced less urea upon stimulation with mixed amino acids, and amino acid clearance was lower in mice with hepatic steatosis. Glucagon-induced ureagenesis was impaired in perfused rat livers with hepatic steatosis. Patients with NAFLD had hyperglucagonemia and increased levels of glucagonotropic amino acids, including alanine in particular. Both glucagon and alanine levels were reduced after diet-induced reduction in Homeostatic Model Assessment for Insulin Resistance (HOMA-IR, a marker of hepatic steatosis). CONCLUSIONS Glucagon regulates amino acid metabolism both non-transcriptionally and transcriptionally. Hepatic steatosis may impair glucagon-dependent enhancement of amino acid catabolism.
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Affiliation(s)
- Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Katrine D Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alberto Santos
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Samuel A J Trammell
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Karolina Sulek
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rune E Kuhre
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Daniel B Andersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anna S Hassing
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Dall
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas T Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Matthew P Gillum
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Signe S Torekov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Johanne A Windeløv
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jenna E Hunt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sasha A S Kjeldsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sara L Jepsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Catherine G Vasilopoulou
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Munich, Germany
| | - Filip K Knop
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Steno Diabetes Center Copenhagen, Gentofte, Denmark
| | - Cathrine Ørskov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel P Werge
- Gastrounit, Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark
| | - Hanne Cathrine Bisgaard
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Lykke Eriksen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Hendrik Vilstrup
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Lise Lotte Gluud
- Gastrounit, Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department for Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
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16
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Acosta-Montalvo A, Saponaro C, Kerr-Conte J, Prehn JHM, Pattou F, Bonner C. Proglucagon-Derived Peptides Expression and Secretion in Rat Insulinoma INS-1 Cells. Front Cell Dev Biol 2020; 8:590763. [PMID: 33240888 PMCID: PMC7683504 DOI: 10.3389/fcell.2020.590763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 10/20/2020] [Indexed: 11/26/2022] Open
Abstract
Rat insulinoma INS-1 cells are widely used to study insulin secretory mechanisms. Studies have shown that a population of INS-1 cells are bi-hormonal, co-expressing insulin, and proglucagon proteins. They coined this population as immature cells since they co-secrete proglucagon-derived peptides from the same secretory vesicles similar to that of insulin. Since proglucagon encodes multiple peptides including glucagon, glucagon-like-peptide-1 (GLP-1), GLP-2, oxyntomodulin, and glicentin, their specific expression and secretion are technically challenging. In this study, we aimed to focus on glucagon expression which shares the same amino acid sequence with glicentin and proglucagon. Validation of the anti-glucagon antibody (Abcam) by Western blotting techniques revealed that the antibody detects proglucagon (≈ 20 kDa), glicentin (≈ 9 kDa), and glucagon (≈ 3 kDa) in INS-1 cells and primary islets, all of which were absent in the kidney cell line (HEK293). Using the validated anti-glucagon antibody, we showed by immunofluorescence imaging that a population of INS-1 cells co-express insulin and proglucagon-derived proteins. Furthermore, we found that chronic treatment of INS-1 cells with high-glucose decreases insulin and glucagon content, and also reduces the percentage of bi-hormonal cells. In line with insulin secretion, we found glucagon and glicentin secretion to be induced in a glucose-dependent manner. We conclude that INS-1 cells are a useful model to study glucose-stimulated insulin secretion, but not that of glucagon or glicentin. Our study suggests Western blotting technique as an important tool for researchers to study proglucagon-derived peptides expression and regulation in primary islets in response to various metabolic stimuli.
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Affiliation(s)
- Ana Acosta-Montalvo
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Chiara Saponaro
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Julie Kerr-Conte
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Jochen H M Prehn
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - François Pattou
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France.,Chirurgie Endocrinienne et Métabolique, CHU Lille, Lille, France
| | - Caroline Bonner
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France.,Institut Pasteur de Lille, Lille, France
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17
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Galsgaard KD, Jepsen SL, Kjeldsen SAS, Pedersen J, Wewer Albrechtsen NJ, Holst JJ. Alanine, arginine, cysteine, and proline, but not glutamine, are substrates for, and acute mediators of, the liver-α-cell axis in female mice. Am J Physiol Endocrinol Metab 2020; 318:E920-E929. [PMID: 32255678 DOI: 10.1152/ajpendo.00459.2019] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The aim of this study was to identify the amino acids that stimulate glucagon secretion in mice and whose metabolism depends on glucagon receptor signaling. Pancreata of female C57BL/6JRj mice were perfused with 19 individual amino acids and pyruvate (at 10 mM), and secretion of glucagon was assessed using a specific glucagon radioimmunoassay. Separately, a glucagon receptor antagonist (GRA; 25-2648, 100 mg/kg) or vehicle was administered to female C57BL/6JRj mice 3 h before an intraperitoneal injection of four different isomolar amino acid mixtures (in total 7 µmol/g body wt) as follows: mixture 1 contained alanine, arginine, cysteine, and proline; mixture 2 contained aspartate, glutamate, histidine, and lysine; mixture 3 contained citrulline, methionine, serine, and threonine; and mixture 4 contained glutamine, leucine, isoleucine, and valine. Blood glucose, plasma glucagon, amino acid, and insulin concentrations were measured using well-characterized methodologies. Alanine (P = 0.03), arginine (P < 0.0001), cysteine (P = 0.01), glycine (P = 0.02), lysine (P = 0.02), and proline (P = 0.03), but not glutamine (P = 0.9), stimulated glucagon secretion from the perfused mouse pancreas. However, when the four isomolar amino acid mixtures were administered in vivo, the four mixtures elicited similar glucagon responses (P > 0.5). Plasma concentrations of total amino acids in vivo were higher after administration of GRA when mixture 1 (P = 0.004) or mixture 3 (P = 0.04) were injected. Our data suggest that alanine, arginine, cysteine, and proline, but not glutamine, are involved in the acute regulation of the liver-α-cell axis in female mice, as they all increased glucagon secretion and their disappearance rate was altered by GRA.
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Affiliation(s)
- Katrine D Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sara L Jepsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sasha A S Kjeldsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Nephrology and Endocrinology, Nordsjaellands Hospital Hilleroed, University of Copenhagen, Hilleroed, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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18
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Galsgaard KD, Pedersen J, Kjeldsen SAS, Winther-Sørensen M, Stojanovska E, Vilstrup H, Ørskov C, Wewer Albrechtsen NJ, Holst JJ. Glucagon receptor signaling is not required for N-carbamoyl glutamate- and l-citrulline-induced ureagenesis in mice. Am J Physiol Gastrointest Liver Physiol 2020; 318:G912-G927. [PMID: 32174131 DOI: 10.1152/ajpgi.00294.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Glucagon regulates the hepatic amino acid metabolism and increases ureagenesis. Ureagenesis is activated by N-acetylglutamate (NAG), formed via activation of N-acetylglutamate synthase (NAGS). With the aim to identify the steps whereby glucagon both acutely and chronically regulates ureagenesis, we investigated whether glucagon receptor-mediated activation of ureagenesis is required in a situation where NAGS activity and/or NAG levels are sufficient to activate the first step of the urea cycle in vivo. Female C57BL/6JRj mice treated with a glucagon receptor antagonist (GRA), glucagon receptor knockout (Gcgr-/-) mice, and wild-type (Gcgr+/+) littermates received an intraperitoneal injection of N-carbamoyl glutamate (Car; a stable variant of NAG), l-citrulline (Cit), Car and Cit (Car + Cit), or PBS. In separate experiments, Gcgr-/- and Gcgr+/+ mice were administered N-carbamoyl glutamate and l-citrulline (wCar + wCit) in the drinking water for 8 wk. Car, Cit, and Car + Cit significantly (P < 0.05) increased plasma urea concentrations, independently of pharmacological and genetic disruption of glucagon receptor signaling (P = 0.9). Car increased blood glucose concentrations equally in GRA- and vehicle-treated mice (P = 0.9), whereas the increase upon Car + Cit was impaired in GRA-treated mice (P = 0.008). Blood glucose concentrations remained unchanged in Gcgr-/- mice upon Car (P = 0.2) and Car + Cit (P = 0.9). Eight weeks administration of wCar + wCit did not change blood glucose (P > 0.2), plasma amino acid (P > 0.4), and urea concentrations (P > 0.3) or the area of glucagon-positive cells (P > 0.3) in Gcgr-/- and Gcgr+/+ mice. Our data suggest that glucagon-mediated activation of ureagenesis is not required when NAGS activity and/or NAG levels are sufficient to activate the first step of the urea cycle.NEW & NOTEWORTHY Hepatic ureagenesis is essential in amino acid metabolism and is importantly regulated by glucagon, but the exact mechanism is unclear. With the aim to identify the steps whereby glucagon both acutely and chronically regulates ureagenesis, we here show, contrary to our hypothesis, that glucagon receptor-mediated activation of ureagenesis is not required when N-acetylglutamate synthase activity and/or N-acetylglutamate levels are sufficient to activate the first step of the urea cycle in vivo.
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Affiliation(s)
- Katrine D Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Endocrinology and Nephrology, Nordsjaellands Hospital Hilleroed, Hilleroed, Denmark
| | - Sasha A S Kjeldsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elena Stojanovska
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hendrik Vilstrup
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Cathrine Ørskov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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19
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Modvig IM, Andersen DB, Grunddal KV, Kuhre RE, Martinussen C, Christiansen CB, Ørskov C, Larraufie P, Kay RG, Reimann F, Gribble FM, Hartmann B, Bojsen-Møller KN, Madsbad S, Wewer Albrechtsen NJ, Holst JJ. Secretin release after Roux-en-Y gastric bypass reveals a population of glucose-sensitive S cells in distal small intestine. Int J Obes (Lond) 2020; 44:1859-1871. [PMID: 32015474 PMCID: PMC7445113 DOI: 10.1038/s41366-020-0541-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 12/17/2019] [Accepted: 01/16/2020] [Indexed: 11/09/2022]
Abstract
OBJECTIVES Gastrointestinal hormones contribute to the beneficial effects of Roux-en-Y gastric bypass surgery (RYGB) on glycemic control. Secretin is secreted from duodenal S cells in response to low luminal pH, but it is unknown whether its secretion is altered after RYGB and if secretin contributes to the postoperative improvement in glycemic control. We hypothesized that secretin secretion increases after RYGB as a result of the diversion of nutrients to more distal parts of the small intestine, and thereby affects islet hormone release. METHODS A specific secretin radioimmunoassay was developed, evaluated biochemically, and used to quantify plasma concentrations of secretin in 13 obese individuals before, 1 week after, and 3 months after RYGB. Distribution of secretin and its receptor was assessed by RNA sequencing, mass-spectrometry and in situ hybridization in human and rat tissues. Isolated, perfused rat intestine and pancreas were used to explore the molecular mechanism underlying glucose-induced secretin secretion and to study direct effects of secretin on glucagon, insulin, and somatostatin secretion. Secretin was administered alone or in combination with GLP-1 to non-sedated rats to evaluate effects on glucose regulation. RESULTS Plasma postprandial secretin was more than doubled in humans after RYGB (P < 0.001). The distal small intestine harbored secretin expressing cells in both rats and humans. Glucose increased the secretion of secretin in a sodium-glucose cotransporter dependent manner when administered to the distal part but not into the proximal part of the rat small intestine. Secretin stimulated somatostatin secretion (fold change: 1.59, P < 0.05) from the perfused rat pancreas but affected neither insulin (P = 0.2) nor glucagon (P = 0.97) secretion. When administered to rats in vivo, insulin secretion was attenuated and glucagon secretion increased (P = 0.04), while blood glucose peak time was delayed (from 15 to 45 min) and gastric emptying time prolonged (P = 0.004). CONCLUSIONS Glucose-sensing secretin cells located in the distal part of the small intestine may contribute to increased plasma concentrations observed after RYGB. The metabolic role of the distal S cells warrants further studies.
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Affiliation(s)
- Ida M Modvig
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Daniel B Andersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kaare V Grunddal
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rune E Kuhre
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Charlotte B Christiansen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Cathrine Ørskov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Pierre Larraufie
- Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | - Richard G Kay
- Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | - Frank Reimann
- Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | - Fiona M Gribble
- Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Sten Madsbad
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. .,Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. .,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. .,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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20
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Holst JJ, Wewer Albrechtsen NJ. Methods and Guidelines for Measurement of Glucagon in Plasma. Int J Mol Sci 2019; 20:E5416. [PMID: 31671667 PMCID: PMC6862148 DOI: 10.3390/ijms20215416] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 11/16/2022] Open
Abstract
Glucagon circulates in concentrations in the low picomolar range, which is demanding regarding the sensitivity of the methods for quantification applied. In addition, the differential and tissue specific proteolytic processing of the glucagon precursor and the presence in of several glucagon-like sequences, not only in the precursor of glucagon, but also in a number of other peptides of the glucagon-secretin family of peptides, put special demands on the specificity of the assays. Finally, experience has shown that unspecific interference of plasma components has presented additional problems. All of these problems have resulted in a lot of diverging results concerning measured and reported glucagon responses in both humans and experimental animals that have and still are causing considerable debate and controversy. There is very solid evidence that glucagon is an important hormone in human and mammalian metabolism, but its precise physiological role in glucose and lipid metabolism and in metabolic disease has been difficult to establish, not least because of these difficulties. It was our purpose with this review to discuss the methods of glucagon quantification and discuss pitfalls and sources of error. We also reviewed some of the dogmas regarding glucagon secretion in the light of the methodological difficulties.
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Affiliation(s)
- 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.
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.
- Department of Clinical Biochemistry, Rigshospitalet, 2100 Copenhagen, Denmark.
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.
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21
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Gaspers LD, Pierobon N, Thomas AP. Intercellular calcium waves integrate hormonal control of glucose output in the intact liver. J Physiol 2019; 597:2867-2885. [PMID: 30968953 PMCID: PMC6647271 DOI: 10.1113/jp277650] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 04/08/2019] [Indexed: 11/21/2022] Open
Abstract
Key points Sympathetic outflow and circulating glucogenic hormones both regulate liver function by increasing cytosolic calcium, although how these calcium signals are integrated at the tissue level is currently unknown. We show that stimulation of hepatic nerve fibres or perfusing the liver with physiological concentrations of vasopressin only will evoke localized cytosolic calcium oscillations and modest increases in hepatic glucose production. The combination of these stimuli acted synergistically to convert localized and asynchronous calcium responses into co‐ordinated intercellular calcium waves that spread throughout the liver lobule and elicited a synergistic increase in hepatic glucose production. The results obtained in the present study demonstrate that subthreshold levels of one hormone can create an excitable medium across the liver lobule, which allows global propagation of calcium signals in response to local sympathetic innervation and integration of metabolic regulation by multiple hormones. This enables the liver lobules to respond as functional units to produce full‐strength metabolic output at physiological levels of hormone.
Abstract Glucogenic hormones, including catecholamines and vasopressin, induce frequency‐modulated cytosolic Ca2+ oscillations in hepatocytes, and these propagate as intercellular Ca2+ waves via gap junctions in the intact liver. We investigated the role of co‐ordinated Ca2+ waves as a mechanism for integrating multiple endocrine and neuroendocrine inputs to control hepatic glucose production in perfused rat liver. Sympathetic nerve stimulation elicited localized Ca2+ increases that were restricted to hepatocytes in the periportal zone. During perfusion with subthreshold vasopressin, sympathetic stimulation converted asynchronous Ca2+ signals in a limited number of hepatocytes into co‐ordinated intercellular Ca2+ waves that propagated across entire lobules. A similar synergism was observed between physiological concentrations of glucagon and vasopressin, where glucagon also facilitated the recruitment of hepatocytes into a Ca2+ wave. Hepatic glucose production was significantly higher with intralobular Ca2+ waves. We propose that inositol 1,4,5‐trisphosphate (IP3)‐dependent Ca2+ signalling gives rise to an excitable medium across the functional syncytium of the hepatic lobule, co‐ordinating and amplifying the metabolic responses to multiple hormonal inputs. Sympathetic outflow and circulating glucogenic hormones both regulate liver function by increasing cytosolic calcium, although how these calcium signals are integrated at the tissue level is currently unknown. We show that stimulation of hepatic nerve fibres or perfusing the liver with physiological concentrations of vasopressin only will evoke localized cytosolic calcium oscillations and modest increases in hepatic glucose production. The combination of these stimuli acted synergistically to convert localized and asynchronous calcium responses into co‐ordinated intercellular calcium waves that spread throughout the liver lobule and elicited a synergistic increase in hepatic glucose production. The results obtained in the present study demonstrate that subthreshold levels of one hormone can create an excitable medium across the liver lobule, which allows global propagation of calcium signals in response to local sympathetic innervation and integration of metabolic regulation by multiple hormones. This enables the liver lobules to respond as functional units to produce full‐strength metabolic output at physiological levels of hormone.
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Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Nicola Pierobon
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
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22
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Galsgaard KD, Pedersen J, Knop FK, Holst JJ, Wewer Albrechtsen NJ. Glucagon Receptor Signaling and Lipid Metabolism. Front Physiol 2019; 10:413. [PMID: 31068828 PMCID: PMC6491692 DOI: 10.3389/fphys.2019.00413] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 03/26/2019] [Indexed: 01/04/2023] Open
Abstract
Glucagon is secreted from the pancreatic alpha cells upon hypoglycemia and stimulates hepatic glucose production. Type 2 diabetes is associated with dysregulated glucagon secretion, and increased glucagon concentrations contribute to the diabetic hyperglycemia. Antagonists of the glucagon receptor have been considered as glucose-lowering therapy in type 2 diabetes patients, but their clinical applicability has been questioned because of reports of therapy-induced increments in liver fat content and increased plasma concentrations of low-density lipoprotein. Conversely, in animal models, increased glucagon receptor signaling has been linked to improved lipid metabolism. Glucagon acts primarily on the liver and by regulating hepatic lipid metabolism glucagon may reduce hepatic lipid accumulation and decrease hepatic lipid secretion. Regarding whole-body lipid metabolism, it is controversial to what extent glucagon influences lipolysis in adipose tissue, particularly in humans. Glucagon receptor agonists combined with glucagon-like peptide 1 receptor agonists (dual agonists) improve dyslipidemia and reduce hepatic steatosis. Collectively, emerging data support an essential role of glucagon for lipid metabolism.
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Affiliation(s)
- Katrine D Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiology, Nephrology and Endocrinology, Nordsjællands Hospital Hillerød, University of Copenhagen, Hillerød, Denmark
| | - Filip K Knop
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, Gentofte Hospital, Hellerup, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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23
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Galsgaard KD, Winther-Sørensen M, Pedersen J, Kjeldsen SAS, Rosenkilde MM, Wewer Albrechtsen NJ, Holst JJ. Glucose and amino acid metabolism in mice depend mutually on glucagon and insulin receptor signaling. Am J Physiol Endocrinol Metab 2019; 316:E660-E673. [PMID: 30807215 DOI: 10.1152/ajpendo.00410.2018] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon and insulin are important regulators of blood glucose. The importance of insulin receptor signaling for alpha-cell secretion and of glucagon receptor signaling for beta-cell secretion is widely discussed and of clinical interest. Amino acids are powerful secretagogues for both hormones, and glucagon controls amino acid metabolism through ureagenesis. The role of insulin in amino acid metabolism is less clear. Female C57BL/6JRj mice received an insulin receptor antagonist (IRA) (S961; 30 nmol/kg), a glucagon receptor antagonist (GRA) (25-2648; 100 mg/kg), or both GRA and IRA (GRA + IRA) 3 h before intravenous administration of similar volumes of saline, glucose (0.5 g/kg), or amino acids (1 µmol/g) while anesthetized with isoflurane. IRA caused basal hyperglycemia, hyperinsulinemia, and hyperglucagonemia. Unexpectedly, IRA lowered basal plasma concentrations of amino acids, whereas GRA increased amino acids, lowered glycemia, and increased glucagon but did not influence insulin concentrations. After administration of GRA + IRA, insulin secretion was significantly reduced compared with IRA administration alone. Blood glucose responses to a glucose and amino acid challenge were similar after vehicle and GRA + IRA administration but greater after IRA and lower after GRA. Anesthesia may have influenced the results, which otherwise strongly suggest that both hormones are essential for the maintenance of glucose homeostasis and that the secretion of both is regulated by powerful negative feedback mechanisms. In addition, insulin limits glucagon secretion, while endogenous glucagon stimulates insulin secretion, revealed during lack of insulin autocrine feedback. Finally, glucagon receptor signaling seems to be of greater importance for amino acid metabolism than insulin receptor signaling.
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Affiliation(s)
- Katrine D Galsgaard
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Marie Winther-Sørensen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Jens Pedersen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Department of Cardiology, Nephrology and Endocrinology, Nordsjaellands Hospital Hilleroed, University of Copenhagen, Hilleroed, Denmark
| | - Sasha A S Kjeldsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Mette M Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Nicolai J Wewer Albrechtsen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen , Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Jens J Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
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24
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Ronn J, Jensen EP, Wewer Albrechtsen NJ, Holst JJ, Sorensen CM. Glucagon-like peptide-1 acutely affects renal blood flow and urinary flow rate in spontaneously hypertensive rats despite significantly reduced renal expression of GLP-1 receptors. Physiol Rep 2018; 5. [PMID: 29233907 PMCID: PMC5727271 DOI: 10.14814/phy2.13503] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 10/17/2017] [Accepted: 10/19/2017] [Indexed: 02/06/2023] Open
Abstract
Glucagon‐like peptide‐1 (GLP‐1) is an incretin hormone increasing postprandial insulin release. GLP‐1 also induces diuresis and natriuresis in humans and rodents. The GLP‐1 receptor is extensively expressed in the renal vascular tree in normotensive rats where acute GLP‐1 treatment leads to increased mean arterial pressure (MAP) and increased renal blood flow (RBF). In hypertensive animal models, GLP‐1 has been reported both to increase and decrease MAP. The aim of this study was to examine expression of renal GLP‐1 receptors in spontaneously hypertensive rats (SHR) and to assess the effect of acute intrarenal infusion of GLP‐1. We hypothesized that GLP‐1 would increase diuresis and natriuresis and reduce MAP in SHR. Immunohistochemical staining and in situ hybridization for the GLP‐1 receptor were used to localize GLP‐1 receptors in the kidney. Sevoflurane‐anesthetized normotensive Sprague–Dawley rats and SHR received a 20 min intrarenal infusion of GLP‐1 and changes in MAP, RBF, heart rate, dieresis, and natriuresis were measured. The vasodilatory effect of GLP‐1 was assessed in isolated interlobar arteries from normo‐ and hypertensive rats. We found no expression of GLP‐1 receptors in the kidney from SHR. However, acute intrarenal infusion of GLP‐1 increased MAP, RBF, dieresis, and natriuresis without affecting heart rate in both rat strains. These results suggest that the acute renal effects of GLP‐1 in SHR are caused either by extrarenal GLP‐1 receptors activating other mechanisms (e.g., insulin) to induce the renal changes observed or possibly by an alternative renal GLP‐1 receptor.
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Affiliation(s)
- Jonas Ronn
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elisa P Jensen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Charlotte M Sorensen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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25
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Galsgaard KD, Winther-Sørensen M, Ørskov C, Kissow H, Poulsen SS, Vilstrup H, Prehn C, Adamski J, Jepsen SL, Hartmann B, Hunt J, Charron MJ, Pedersen J, Wewer Albrechtsen NJ, Holst JJ. Disruption of glucagon receptor signaling causes hyperaminoacidemia exposing a possible liver-alpha-cell axis. Am J Physiol Endocrinol Metab 2018; 314:E93-E103. [PMID: 28978545 PMCID: PMC6048389 DOI: 10.1152/ajpendo.00198.2017] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glucagon secreted from the pancreatic alpha-cells is essential for regulation of blood glucose levels. However, glucagon may play an equally important role in the regulation of amino acid metabolism by promoting ureagenesis. We hypothesized that disruption of glucagon receptor signaling would lead to an increased plasma concentration of amino acids, which in a feedback manner stimulates the secretion of glucagon, eventually associated with compensatory proliferation of the pancreatic alpha-cells. To address this, we performed plasma profiling of glucagon receptor knockout ( Gcgr-/-) mice and wild-type (WT) littermates using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics, and tissue biopsies from the pancreas were analyzed for islet hormones and by histology. A principal component analysis of the plasma metabolome from Gcgr-/- and WT littermates indicated amino acids as the primary metabolic component distinguishing the two groups of mice. Apart from their hyperaminoacidemia, Gcgr-/- mice display hyperglucagonemia, increased pancreatic content of glucagon and somatostatin (but not insulin), and alpha-cell hyperplasia and hypertrophy compared with WT littermates. Incubating cultured α-TC1.9 cells with a mixture of amino acids (Vamin 1%) for 30 min and for up to 48 h led to increased glucagon concentrations (~6-fold) in the media and cell proliferation (~2-fold), respectively. In anesthetized mice, a glucagon receptor-specific antagonist (Novo Nordisk 25-2648, 100 mg/kg) reduced amino acid clearance. Our data support the notion that glucagon secretion and hepatic amino acid metabolism are linked in a close feedback loop, which operates independently of normal variations in glucose metabolism.
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Affiliation(s)
- Katrine D Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Cathrine Ørskov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Hannelouise Kissow
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Steen S Poulsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Hendrik Vilstrup
- Department of Hepato-Gastroenterology, Aarhus University Hospital , Aarhus , Denmark
| | - Cornelia Prehn
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum, German Research Center for Environmental Health, München-Neuerberg, Germany
| | - Jerzy Adamski
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum, German Research Center for Environmental Health, München-Neuerberg, Germany
- Lehrstul für Experimentelle Genetik, Technishe Universität München, Freising- Weihenstephan , Germany
- German Center for Diabetes Research, München-Nueherberg, Germany
| | - Sara L Jepsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Jenna Hunt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Maureen J Charron
- Departments of Biochemistry, Obstetrics and Gynecology and Women's Health, and Medicine, Albert Einstein College of Medicine , New York, New York
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
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26
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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.
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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
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