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Lauritzen ES, Svart MV, Voss T, Møller N, Bjerre M. Impact of Acutely Increased Endogenous- and Exogenous Ketone Bodies on FGF21 Levels in Humans. Endocr Res 2021; 46:20-27. [PMID: 33074729 DOI: 10.1080/07435800.2020.1831015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE Fibroblast growth factor (FGF) 21 is a circulating hormone with metabolic regulatory importance. In mice, FGF21 increases in response to a ketogenic diet and fasting. In humans, a similar increase is only observed after prolonged starvation. We aim to study the acute effects of ketone bodies on circulating FGF21 levels in humans. METHODS Participants from three randomized, placebo-controlled crossover studies, with increased endogenous or exogenous ketone bodies, were included. Study 1: patients with type 1 diabetes (T1D) (n = 9) were investigated after a) insulin deprivation and lipopolysaccharide (LPS) injection and b) insulin-controlled euglycemia. Study 2: patients with T1D (n = 9) were investigated after a) total insulin deprivation for 9 hours and b) insulin-controlled euglycemia. Study 3: Healthy adults (n = 9) were examined during a) 3-hydroxybutyrate (OHB) infusion and b) saline infusion. Plasma FGF21 was measured with immunoassay in serial samples. RESULTS Circulating OHB levels were significantly increased to 1.3, 1.5, and 5.5 mmol/l in the three studies, but no correlations with FGF21 levels were found. Also, no correlations between FGF21, insulin, or glucagon were found. Insulin deprivation and LPS injection resulted in increased plasma FGF21 levels at t = 120 min (p = .005) which normalized at t = 240 min. CONCLUSION We found no correlation between circulating FGF21 levels and levels of ketone bodies. This suggests that it is not ketosis per se which controls FGF21 production, but instead a rather more complex regulatory mechanism. TRIAL REGISTRATION clinicaltrials.gov ID number: Study 1: NCT02157155 (5/6-2014), study 2: NCT02077348 (4/3-2014), and study 3: NCT02357550 (6/2-2015).
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Affiliation(s)
- Esben Stistrup Lauritzen
- Medical Research Laboratory, Aarhus University , Aarhus N, Denmark
- Steno Diabetes Center Aarhus, Aarhus University Hospital , Aarhus N, Denmark
| | - Mads Vandsted Svart
- Medical Research Laboratory, Aarhus University , Aarhus N, Denmark
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital , Aarhus N, Denmark
| | - Thomas Voss
- Steno Diabetes Center Aarhus, Aarhus University Hospital , Aarhus N, Denmark
| | - Niels Møller
- Medical Research Laboratory, Aarhus University , Aarhus N, Denmark
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital , Aarhus N, Denmark
| | - Mette Bjerre
- Medical Research Laboratory, Aarhus University , Aarhus N, Denmark
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Haidar A. Insulin-and-Glucagon Artificial Pancreas Versus Insulin-Alone Artificial Pancreas: A Short Review. Diabetes Spectr 2019; 32:215-221. [PMID: 31462876 PMCID: PMC6695257 DOI: 10.2337/ds18-0097] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
IN BRIEF The advantage of the insulin-and-glucagon artificial pancreas is based on the rapid effect of subcutaneous glucagon delivery in preventing hypoglycemia compared to suspension of insulin delivery. In short-term studies, the dual-hormone artificial pancreas reduced daytime hypoglycemia, especially during exercise, compared to the insulin-alone artificial pancreas, but the insulin-alone system seemed sufficient in eliminating nocturnal hypoglycemia. The comparative benefits of the single- and dual-hormone systems for improving A1C and preventing severe hypoglycemia remain unknown.
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Affiliation(s)
- Ahmad Haidar
- Department of Biomedical Engineering, McGill University, Montreal, Quebec, Canada
- Division of Endocrinology and Metabolism, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
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3
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Peters TM, Haidar A. Dual-hormone artificial pancreas: benefits and limitations compared with single-hormone systems. Diabet Med 2018; 35:450-459. [PMID: 29337384 DOI: 10.1111/dme.13581] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/10/2018] [Indexed: 12/17/2022]
Abstract
Technological advances have made the artificial pancreas a reality. This has the potential to improve the lives of individuals with Type 1 diabetes by reducing the risk of hypoglycaemia, achieving better overall glucose control, and enhancing quality of life. Both single-hormone (insulin-only) and dual-hormone (insulin and glucagon) systems have been developed; however, a focused review of the relative benefits of each artificial pancreas system is needed. We reviewed studies that directly compared single- and dual-hormone systems to evaluate the efficacy of each system for preventing hypoglycaemia and maintaining glycaemic control, as well as their utility in specific situations including during exercise, overnight and during the prandial period. We observed additional benefits with the dual-hormone artificial pancreas for reducing the risk of hypoglycaemic events overall and during exercise over the study duration. The single-hormone artificial pancreas was sufficient for maintenance of euglycaemia in the overnight period and for preventing late-onset post-exercise hypoglycaemia. Future comparative studies of longer duration are required to determine whether one system is superior for improving mean glucose control, eliminating severe hypoglycaemia, or improving quality of life.
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Affiliation(s)
- T M Peters
- Division of Endocrinology and Metabolism, Faculty of Medicine
| | - A Haidar
- Division of Endocrinology and Metabolism, Faculty of Medicine
- Department of Biomedical Engineering, McGill University
- The Research Institute of the McGill University Health Centre, Montreal, Canada
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Blauw H, Wendl I, DeVries JH, Heise T, Jax T. Pharmacokinetics and pharmacodynamics of various glucagon dosages at different blood glucose levels. Diabetes Obes Metab 2016; 18:34-9. [PMID: 26343550 DOI: 10.1111/dom.12571] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/05/2015] [Accepted: 08/28/2015] [Indexed: 11/29/2022]
Abstract
AIMS To evaluate the pharmacokinetics and pharmacodynamics of different doses of glucagon administered subcutaneously (s.c.) at different blood glucose levels. METHODS This study was an open-label, randomized, three-period, cross-over experiment in 6 patients with type 1 diabetes. During each of the three periods, different blood glucose levels were established in four consecutive steps (8, 6, 4 and 2.8 mmol/l) and glucagon was given at each blood glucose level in doses from 0.11 to 0.44 mg and 0.33, 0.66 and 1 mg at the lowest glucose concentration. RESULTS Maximum glucagon concentration and area under the curve increased with increasing glucagon dose. Maximum glucagon concentration was reached after 10-20 min. Glucagon raised blood glucose in a dose-dependent manner at different baseline blood glucose levels. The median glucose excursion ranged from 2.6 to 6.2 mmol/l. Time to maximum glucose concentration was dose-dependent for the glucagon doses at 2.8 mmol/l, with median values from 40 to 80 min. CONCLUSIONS Glucagon administered s.c. produces a stable pharmacokinetic and pharmacodynamic response at lower doses than the usual rescue dose and across a range of hypo- to hyperglycaemic blood glucose levels. This supports the use of small glucagon doses in the artificial pancreas to correct and prevent hypoglycaemia.
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Affiliation(s)
- H Blauw
- Inreda Diabetic BV, Goor, The Netherlands
- Department of Endocrinology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - I Wendl
- Profil Institut für Stoffwechselforschung GmbH, Neuss, Germany
| | - J H DeVries
- Department of Endocrinology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - T Heise
- Profil Institut für Stoffwechselforschung GmbH, Neuss, Germany
| | - T Jax
- Profil Institut für Stoffwechselforschung GmbH, Neuss, Germany
- Herzzentrum Wuppertal, Universität Witten-Herdecke, Witten, Germany
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5
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Involvement of steatosis-induced glucagon resistance in hyperglucagonaemia. Med Hypotheses 2016; 86:100-3. [DOI: 10.1016/j.mehy.2015.10.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/28/2015] [Indexed: 12/18/2022]
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Hinshaw L, Mallad A, Dalla Man C, Basu R, Cobelli C, Carter RE, Kudva YC, Basu A. Glucagon sensitivity and clearance in type 1 diabetes: insights from in vivo and in silico experiments. Am J Physiol Endocrinol Metab 2015; 309:E474-86. [PMID: 26152766 PMCID: PMC4556882 DOI: 10.1152/ajpendo.00236.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 06/29/2015] [Indexed: 11/22/2022]
Abstract
Glucagon use in artificial pancreas for type 1 diabetes (T1D) is being explored for prevention and rescue from hypoglycemia. However, the relationship between glucagon stimulation of endogenous glucose production (EGP) viz., hepatic glucagon sensitivity, and prevailing glucose concentrations has not been examined. To test the hypothesis that glucagon sensitivity is increased at hypoglycemia vs. euglycemia, we studied 29 subjects with T1D randomized to a hypoglycemia or euglycemia clamp. Each subject was studied at three glucagon doses at euglycemia or hypoglycemia, with EGP measured by isotope dilution technique. The peak EGP increments and the integrated EGP response increased with increasing glucagon dose during euglycemia and hypoglycemia. However, the difference in dose response based on glycemia was not significant despite higher catecholamine concentrations in the hypoglycemia group. Knowledge of glucagon's effects on EGP was used to develop an in silico glucagon action model. The model-derived output fitted the obtained data at both euglycemia and hypoglycemia for all glucagon doses tested. Glucagon clearance did not differ between glucagon doses studied in both groups. Therefore, the glucagon controller of a dual hormone control system may not need to adjust glucagon sensitivity, and hence glucagon dosing, based on glucose concentrations during euglycemia and hypoglycemia.
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Affiliation(s)
- Ling Hinshaw
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota
| | - Ashwini Mallad
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padua, Italy
| | - Rita Basu
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota;
| | - Claudio Cobelli
- Department of Information Engineering, University of Padova, Padua, Italy
| | - Rickey E Carter
- Department of Health Sciences Research, Mayo College of Medicine, Rochester, Minnesota; and
| | - Yogish C Kudva
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota
| | - Ananda Basu
- Endocrine Research Unit, Division of Endocrinology, Mayo College of Medicine, Rochester, Minnesota
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7
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McDonald MW, Murray MR, Hall KE, Noble EG, Melling CWJ. Morphological assessment of pancreatic islet hormone content following aerobic exercise training in rats with poorly controlled Type 1 diabetes mellitus. Islets 2014; 6:e29221. [PMID: 25483959 PMCID: PMC4594201 DOI: 10.4161/isl.29221] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Regular exercise has been shown to improve many complications of Type 1 diabetes mellitus (T1DM) including enhanced glucose tolerance and increased cardiac function. While exercise training has been shown to increase insulin content in pancreatic islets of rats with T1DM, experimental models were severely hyperglycemic and not undergoing insulin treatment. Further, research to date has yet to determine how exercise training alters glucagon content in pancreatic islets. The purpose of the present investigation was to determine the impact of a 10-week aerobic training program on pancreatic islet composition in insulin-treated rats with T1DM. Second, it was determined whether the acute, exercise-mediated reduction in blood glucose experienced in rats with T1DM would become larger in magnitude following aerobic exercise training. Diabetes was induced in male Sprague-Dawley rats by multiple low dose injections of streptozotocin (20mg/kg i.p.) and moderate intensity aerobic exercise training was performed on a motorized treadmill for one hour per day for a total of 10 weeks. Rats with T1DM demonstrated significantly less islet insulin, and significantly more islet glucagon hormone content compared with non-T1DM rats, which did not significantly change following aerobic training. The reduction in blood glucose in response to a single exercise bout was similar across 10 weeks of training. Results also support the view that different subpopulations of islets exist, as small islets (<50 μm diameter) had significantly more insulin and glucagon in rats with and without T1DM.
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Affiliation(s)
- Matthew W McDonald
- School of Kinesiology; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
| | - Michael R Murray
- School of Kinesiology; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
| | - Katharine E Hall
- Health and Rehabilitation Sciences; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
| | - Earl G Noble
- School of Kinesiology; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
- Lawson Health Research Institute; University of Western Ontario; London, ON Canada
| | - CW James Melling
- School of Kinesiology; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
- Correspondence to: CW James Melling,
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Castle JR, Engle JM, El Youssef J, Massoud RG, Ward WK. Factors influencing the effectiveness of glucagon for preventing hypoglycemia. J Diabetes Sci Technol 2010; 4:1305-10. [PMID: 21129324 PMCID: PMC3005039 DOI: 10.1177/193229681000400603] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Administration of small, intermittent doses of glucagon during closed-loop insulin delivery markedly reduces the frequency of hypoglycemia. However, in some cases, hypoglycemia occurs despite administration of glucagon in this setting. METHODS Fourteen adult subjects with type 1 diabetes participated in 22 closed-loop studies, duration 21.5±2.0 h. The majority of subjects completed two studies, one with insulin + glucagon, given subcutaneously by algorithm during impending hypoglycemia, and one with insulin+placebo. The more accurate of two subcutaneous glucose sensors was used as the controller input. To better understand reasons for success or failure of glucagon to prevent hypoglycemia, each response to a glucagon dose over 0.5 µg/kg was analyzed (n=19 episodes). RESULTS Hypoglycemia occurred in the hour after glucagon delivery in 37% of these episodes. In the failures, estimated insulin on board was significantly higher versus successes (5.8±0.5 versus 2.9±0.5 U, p<.001). Glucose at the time of glucagon delivery was significantly lower in failures versus successes (86±3 versus 95±3 mg/dl, p=.04). Sensor bias (glucose overestimation) was highly correlated with starting glucose (r=0.65, p=.002). Prior cumulative glucagon dose was not associated with success or failure. CONCLUSION Glucagon may fail to prevent hypoglycemia when insulin on board is high or when glucagon delivery is delayed due to overestimation of glucose by the sensor. Improvements in sensor accuracy and delivery of larger or earlier glucagon doses when insulin on board is high may further reduce the frequency of hypoglycemia.
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Affiliation(s)
- Jessica R Castle
- Oregon Health and Science University, Portland, Oregon 97239, USA.
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9
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Chokkalingam K, Tsintzas K, Snaar JEM, Norton L, Solanky B, Leverton E, Morris P, Mansell P, Macdonald IA. Hyperinsulinaemia during exercise does not suppress hepatic glycogen concentrations in patients with type 1 diabetes: a magnetic resonance spectroscopy study. Diabetologia 2007; 50:1921-1929. [PMID: 17639304 DOI: 10.1007/s00125-007-0747-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Accepted: 05/28/2007] [Indexed: 11/26/2022]
Abstract
AIMS/HYPOTHESIS We compared in vivo changes in liver glycogen concentration during exercise between patients with type 1 diabetes and healthy volunteers. METHODS We studied seven men with type 1 diabetes (mean +/- SEM diabetes duration 10 +/- 2 years, age 33 +/- 3 years, BMI 24 +/- 1 kg/m(2), HbA(1c) 8.1 +/- 0.2% and VO(2) peak 43 +/- 2 ml [kg lean body mass](-1) min(-1)) and five non-diabetic controls (mean +/- SEM age 30 +/- 3 years, BMI 22 +/- 1 kg/m(2), HbA(1c) 5.4 +/- 0.1% and VO(2) peak 52 +/- 4 ml [kg lean body mass](-1) min(-1), before and after a standardised breakfast and after three bouts (EX1, EX2, EX3) of 40 min of cycling at 60% VO(2) peak. (13)C Magnetic resonance spectroscopy of liver glycogen was acquired in a 3.0 T magnet using a surface coil. Whole-body substrate oxidation was determined using indirect calorimetry. RESULTS Blood glucose and serum insulin concentrations were significantly higher (p < 0.05) in the fasting state, during the postprandial period and during EX1 and EX2 in subjects with type 1 diabetes compared with controls. Serum insulin concentration was still different between groups during EX3 (p < 0.05), but blood glucose concentration was similar. There was no difference between groups in liver glycogen concentration before or after the three bouts of exercise, despite the relative hyperinsulinaemia in type 1 diabetes. There were also no differences in substrate oxidation rates between groups. CONCLUSIONS/INTERPRETATION In patients with type 1 diabetes, hyperinsulinaemic and hyperglycaemic conditions during moderate exercise did not suppress hepatic glycogen concentrations. These findings do not support the hypothesis that exercise-induced hypoglycaemia in patients with type 1 diabetes is due to suppression of hepatic glycogen mobilisation.
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Affiliation(s)
- K Chokkalingam
- Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, University of Nottingham, Nottingham, UK
- Queen's Medical Centre, Nottingham, UK
| | - K Tsintzas
- Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, University of Nottingham, Nottingham, UK
| | - J E M Snaar
- Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK
| | - L Norton
- Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, University of Nottingham, Nottingham, UK
| | - B Solanky
- Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK
| | - E Leverton
- Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK
| | - P Morris
- Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK
| | - P Mansell
- Queen's Medical Centre, Nottingham, UK
| | - I A Macdonald
- Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, University of Nottingham, Nottingham, UK.
- School of Biomedical Sciences, Queen's Medical Centre, University of Nottingham, Derby Road, Nottingham, NG7 2UH, UK.
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Charbonneau A, Unson CG, Lavoie JM. High-fat diet-induced hepatic steatosis reduces glucagon receptor content in rat hepatocytes: potential interaction with acute exercise. J Physiol 2006; 579:255-67. [PMID: 17053032 PMCID: PMC2075374 DOI: 10.1113/jphysiol.2006.121954] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Studies have revealed that high-fat (HF) diets promote hyperglycaemia, whole-body insulin resistance and non-alcoholic fatty liver disease (NAFLD). Recently, hepatic glucagon resistance has been shown to occur in rats fed a HF diet. More precisely, diet-induced obesity (DIO) reduces the number of hepatic plasma membrane glucagon receptors (GR), which results in a diminished response to glucagon during a hyperglucagonaemic clamp. The present study was undertaken to test the hypothesis that a HF-DIO is associated with a desensitization and destruction of the hepatic GR. We also hypothesized that a single bout of endurance exercise would modify the GR cellular distribution under our DIO model. Male rats were either fed a standard (SD) or a HF diet for two weeks. Each group was subdivided into a non-exercised (Rest) and an acute exercised (EX) group. The HF diet resulted in a reduction of total hepatic GR (55%) and hepatic plasma membrane GR protein content (20%). These changes were accompanied by a significant increase in endosomal and lysosomal GR content with the feeding of a HF diet. The reduction of GR plasma membrane as well as the increase in endosomal GR was strongly correlated with an increase of PKC-alpha, suggesting a role of PKC-alpha in GR desensitization. EX increased significantly PKC-alpha protein content in both diets, suggesting a role of PKC-alpha in EX-induced GR desensitization. The present results suggest that liver lipid infiltration plays a role in reducing glucagon action in the liver through a reduction in total cellular and plasma membrane GR content. Furthermore, the GR desensitization observed in our in vivo model of HF diet-induced hepatic steatosis and in EX individuals may be regulated by PKC-alpha.
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Charbonneau A, Melancon A, Lavoie C, Lavoie JM. Alterations in hepatic glucagon receptor density and in Gsalpha and Gialpha2 protein content with diet-induced hepatic steatosis: effects of acute exercise. Am J Physiol Endocrinol Metab 2005; 289:E8-14. [PMID: 15687107 DOI: 10.1152/ajpendo.00570.2004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was undertaken to test the hypothesis that a high-fat diet-induced liver lipid infiltration is associated with a reduction of hepatic glucagon receptor density (B(max)) and affinity (K(d)), and with a decrease in stimulatory G protein (G(s)alpha) content while enhancing inhibitory G protein (G(i)alpha(2)) expression. We also hypothesized that, under this dietary condition, a single bout of endurance exercise would restore hepatic glucagon receptor parameters and G protein expression to standard levels. Female Sprague-Dawley rats were fed either a standard (SD) or a high-fat diet (HF; 40% kcal) for 2 wk (n = 20 rats/group). Each dietary group was thereafter subdivided into a nonexercised (Rest) and an acute-exercised group (Ac-Ex). The acute exercise consisted of a single bout of endurance exercise on a treadmill (30 min, 26 m/min, and 0% slope) immediately before being killed. The HF compared with the SD diet was associated with significantly (P < 0.05) higher values in hepatic triglyceride concentrations (123%), fat pad weight, and plasma free fatty acid (FFA) concentrations. The HF diet also resulted in significantly (P < 0.05) lower hepatic glucagon receptor density (45%) and G(s)alpha protein content (75%), as well as higher (P < 0.05) G(i)alpha(2) protein content (27%), with no significant effects on glucagon receptor affinity. Comparisons of all individual liver triglyceride and B(max) values revealed that liver triglycerides were highly (P < 0.003) predictive of the decreased glucagon receptor density (R = -0.512). Although the 30-min exercise bout resulted in some typical exercise effects (P < 0.05), such as an increase in FFA (SD diet), a decrease in insulin levels, and an increase in plasma glucagon concentrations (SD diet), it did not change any of the responses related to liver glucagon receptors and G proteins, with the exception of a significant (P < 0.05) decrease in G(i)alpha(2) protein content under the HF diet. The present results indicate that the feeding of an HF diet is associated with a reduction in plasma membrane hepatic glucagon receptor density and G(s)alpha protein content, which is not attenuated by a 30-min exercise bout. It is suggested that liver lipid infiltration plays a role in reducing glucagon action in the liver through a reduction in glucagon receptor density and glucagon-mediated signal transduction.
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Affiliation(s)
- Alexandre Charbonneau
- Département de Kinésiologie, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montreal, QC, Canada, H3C 3J7
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12
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Légaré A, Drouin R, Milot M, Massicotte D, Péronnet F, Massicotte G, Lavoie C. Increased density of glucagon receptors in liver from endurance-trained rats. Am J Physiol Endocrinol Metab 2001; 280:E193-6. [PMID: 11120674 DOI: 10.1152/ajpendo.2001.280.1.e193] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The binding properties of glucagon receptors were determined in plasma membranes isolated from liver of untrained (n = 6) and swimming endurance-trained Sprague-Dawley male rats (n = 7; 3 h/day, 5 days/wk, for 8 wk). Plasma membranes were purified from liver by aqueous two-phase affinity partitioning, and saturation kinetics were obtained by incubation of plasma membranes (10 microg of proteins/150 microl) with (125)I-labeled glucagon at concentrations ranging from 0.15 to 3.0 nM for 30 min at 30 degrees C. Saturating curve analysis indicated no difference in the affinity of glucagon receptors (0.57 +/- 0.06 and 0.77 +/- 0.09 nM in untrained and trained groups, respectively) but a significant higher glucagon receptor density in liver from untrained vs. trained rats (3.09 +/- 0.12 vs. 4.28 +/- 0.19 pmol/mg proteins). These results suggest that the reported increase in liver glucagon sensitivity in endurance-trained subjects (Drouin R, Lavoie C, Bourque J, Ducros F, Poisson D, and Chiasson J-L. Am J Physiol Endocrinol Metab 274: E23-E28, 1998) could be partly due to an increased glucagon receptor density in response to training.
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Affiliation(s)
- A Légaré
- Département de chimie-biologie, Université du Québec à Trois-Rivières, Trois-Rivières, Quebec G9A 5H7, Canada
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13
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Orskov L, Nyholm B, Yde Hove K, Gravholt CH, Møller N, Schmitz O. Effects of the amylin analogue pramlintide on hepatic glucagon responses and intermediary metabolism in Type 1 diabetic subjects. Diabet Med 1999; 16:867-74. [PMID: 10547215 DOI: 10.1046/j.1464-5491.1999.00162.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS Hepatic glycogen stores have been shown to be depleted, and glucagon stimulated hepatic glucose production reduced, in Type 1 diabetic subjects. Co-administration of amylin and insulin has been shown to replete hepatic glycogen stores in diabetic animal models. The aim of the present study was to investigate the effect of amylin replacement on hepatic glucagon responsiveness in humans. METHODS Thirteen Type 1 diabetic men were studied in a double-blind, placebo-controlled, cross-over study after 4 weeks of subcutaneous pramlintide (30 microg q.i.d.) or placebo administration. Following an overnight fast, plasma glucose was kept above 5 mmol/l (baseline 210-240 min) with an insulin infusion rate of 0.25 mU x kg(-1) x min(-1). To control portal glucagon levels, somatostatin was infused at a rate of 200 microg/h. Basal growth hormone (2 ng x kg(-1) x min(-1)) and glucagon (0.7 ng x kg(-1) x min(-1)) were replaced. Glucagon infusion was increased to 2.1 ng x kg(-1) x min(-1) at 240-360 min (step 1) and to 4.2 ng x kg(-1) x min(-1) at 360-420 min (step 2). RESULTS Baseline plasma glucose (5.59+/-0.16 vs. 5.67+/-0.25 mmol/l) and endogenous glucose production (EGP) (1.32+/-0.22 vs. 1.20+/-0.13 mg x kg(-1). min(-1)) were similar and the response to glucagon was unaffected by pramlintide (glucose: step 1; 6.01+/-0.31 vs. 5.94+/-0.38 mmol/l, step 2; 6.00+/-0.37 vs. 5.96+/-0.50 mmol/l, EGP: step 1; 1.91+/-0.18 vs. 1.83+/-0.15 mg x kg(-1) x min(-1), step 2; 2.08+/-0.17 vs. 1.96+/-0.16 ng x kg(-1) x min(-1), pramlintide vs. placebo). Glucose disposal rates were similar at baseline (2.44+/-0.13 vs. 2.28+/-0.09 mg x kg(-1) x min(-1), pramlintide vs. placebo) as well as during the glucagon challenge (P-values all > 0.2). CONCLUSIONS Co-administration of pramlintide and insulin to Type 1 diabetic subjects for 4 weeks does not change the plasma glucose or endogenous glucose production response to a glucagon challenge, following an overnight fast. In addition, pramlintide administration does not appear to alter insulin-mediated glucose disposal.
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Affiliation(s)
- L Orskov
- Department of Medicine C, University Hospital of Arhus, Denmark
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Shah P, Basu A, Basu R, Rizza R. Impact of lack of suppression of glucagon on glucose tolerance in humans. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E283-90. [PMID: 10444424 DOI: 10.1152/ajpendo.1999.277.2.e283] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
People with type 2 diabetes have defects in both alpha- and beta-cell function. To determine whether lack of suppression of glucagon causes hyperglycemia when insulin secretion is impaired but not when insulin secretion is intact, twenty nondiabetic subjects were studied on two occasions. On both occasions, a "prandial" glucose infusion was given over 5 h while endogenous hormone secretion was inhibited. Insulin was infused so as to mimic either a nondiabetic (n = 10) or diabetic (n = 10) postprandial profile. Glucagon was infused at a rate of 1.25 ng. kg(-1). min(-1), beginning either at time zero to prevent a fall in glucagon (nonsuppressed study day) or at 2 h to create a transient fall in glucagon (suppressed study day). During the "diabetic" insulin profile, lack of glucagon suppression resulted in a marked increase (P < 0.002) in both the peak glucose concentration (11.9 +/- 0.4 vs. 8.9 +/- 0.4 mmol/l) and the area above basal of glucose (927 +/- 77 vs. 546 +/- 112 mmol. l(-1). 6 h) because of impaired (P < 0.001) suppression of glucose production. In contrast, during the "nondiabetic" insulin profile, lack of suppression of glucagon resulted in only a slight increase (P < 0.02) in the peak glucose concentration (9.1 +/- 0.4 vs. 8.4 +/- 0.3 mmol/l) and the area above basal of glucose (654 +/- 146 vs. 488 +/- 118 mmol. l(-1). 6 h). Of interest, when glucagon was suppressed, glucose concentrations differed only minimally during the nondiabetic and diabetic insulin profiles. These data indicate that lack of suppression of glucagon can cause substantial hyperglycemia when insulin availability is limited, therefore implying that inhibitors of glucagon secretion and/or glucagon action are likely to be useful therapeutic agents in such individuals.
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Affiliation(s)
- P Shah
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA
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Nyholm B, Orskov L, Hove KY, Gravholt CH, Møller N, Alberti KG, Moyses C, Kolterman O, Schmitz O. The amylin analog pramlintide improves glycemic control and reduces postprandial glucagon concentrations in patients with type 1 diabetes mellitus. Metabolism 1999; 48:935-41. [PMID: 10421239 DOI: 10.1016/s0026-0495(99)90232-9] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To explore further the effects of the human amylin analog pramlintide on overall glycemic control and postprandial responses of circulating glucose, glucagon, and metabolic intermediates in type 1 diabetes mellitus, 14 male type 1 diabetic patients were examined in a double-blind, placebo-controlled, crossover study. Pramlintide (30 microg four times daily) or placebo were administered for 4 weeks, after which a daytime blood profile (8:30 AM to 4:30 PM) was performed. Serum fructosamine was decreased after pramlintide (314+/-14 micromol/L) compared with placebo (350+/-14 micromol/L, P = .008). On the profile day, the mean plasma glucose (8.3+/-0.7 v 10.2+/-0.8 mmol/L, P = .04) and postprandial concentrations (incremental areas under the curve [AUCs] from 0 to 120 minutes) were significantly decreased during pramlintide administration (P < .01 for both) despite comparable circulating insulin levels (359+/-41 v 340+/-35 pmol/L). Mean blood glycerol values were reduced (0.029+/-0.004 v 0.040+/-0.004 mmol/L, P = .01) and blood alanine levels were elevated (0.274+/-0.012 v 0.246+/-0.008 mmol/L, P = .03) after pramlintide versus placebo. Blood lactate concentrations did not differ during the two regimens. During pramlintide administration, the AUC (0 to 120 minutes) for plasma glucagon after breakfast was diminished (P = .02), and a similar trend was observed following lunch. In addition, peak plasma glucagon concentrations 60 minutes after breakfast (45.8+/-7.3 v 72.4+/-8.0 ng/L, P = .005) and lunch (47.6+/-9.0 v 60.9+/-8.2 ng/L, P = .02) were both decreased following pramlintide. These data indicate that pramlintide (30 microg four times daily) is capable of improving metabolic control in type 1 diabetics. This may relate, in part, to suppression of glucagon concentrations. Longer-term studies are required to ascertain whether these findings are sustained over time.
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Affiliation(s)
- B Nyholm
- Department of Medicine M (Endocrinology and Diabetes), Kommunehospitalet, University Hospital of Aarhus, Denmark
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Kruger DF, Gatcomb PM, Owen SK. Clinical implications of amylin and amylin deficiency. DIABETES EDUCATOR 1999; 25:389-97; quiz 398. [PMID: 10531859 DOI: 10.1177/014572179902500310] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE This paper presents an overview of the physiology of glycemic control and the mechanisms of amylin deficiency in people with diabetes. Benefits of replacement therapy with both pramlintide and insulin are discussed. METHODS The discovery of the pancreatic beta-cell hormone amylin, which is cosecreted with insulin in response to hyperglycemia, has prompted a reanalysis of the mechanisms underlying the control of glucose homeostasis. A review of the current literature on amylin and amylin deficiency provides the basis of this reanalysis, with a discussion of the clinical implications for people with diabetes. RESULTS Amylin appears to work with insulin to regulate plasma glucose concentrations in the bloodstream, suppressing the postprandial secretion of glucagon and restraining the rate of gastric emptying. People with diabetes have a deficiency in the secretion of amylin that parallels the deficiency in insulin secretion, resulting in an excessive inflow of glucose into the bloodstream during the postprandial period. CONCLUSIONS While insulin replacement therapy is a cornerstone of diabetes treatment, replacement of the function of both amylin and insulin may allow a more complete restoration of the normal physiology of glucose control.
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Affiliation(s)
- D F Kruger
- The Division of Endocrinology and Metabolism, Henry Ford Health Systems, Detroit, Michigan (Ms Kruger)
| | - P M Gatcomb
- Yale University, Department of Pediatric Endocrinology, New Haven, Connecticut (Ms Gatcomb )
| | - S K Owen
- Grand Rapids Associated Internists, Grand Rapids, Michigan (Ms Owen)
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Drouin R, Lavoie C, Bourque J, Ducros F, Poisson D, Chiasson JL. Increased hepatic glucose production response to glucagon in trained subjects. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:E23-8. [PMID: 9458743 DOI: 10.1152/ajpendo.1998.274.1.e23] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This study was designed to characterize the impact of endurance training on the hepatic response to glucagon. We measured the effect of glucagon on hepatic glucose production (HGP) in resting trained (n = 8) and untrained (n = 8) healthy male subjects (maximal rate of O2 consumption: 65.9 +/- 1.6 vs. 46.8 +/- 0.6 ml O2.kg-1.min-1, respectively, P < 0.001). Endogenous insulin and glucagon were suppressed by somatostatin (somatotropin release-inhibiting hormone) infusion (450 micrograms/h) over 4 h. Insulin (0.15 mU.kg-1.min-1) was infused throughout the study, and glucagon (1.5 ng.kg-1.min-1) was infused over the last 2 h. During the latter period, plasma glucagon and insulin remained constant at 138.2 +/- 3.1 vs. 145.3 +/- 2.1 ng/l and at 95.5 +/- 4.5 vs. 96.2 +/- 1.9 pmol/l in trained and untrained subjects, respectively. Plasma glucose increased and peaked at 11.4 +/- 1.1 mmol/l in trained subjects and at 8.9 +/- 0.8 mmol/l in untrained subjects (P < 0.001). During glucagon stimulation, the mean increase in HGP area under the curve was 15.8 +/- 2.8 mol.kg-1.min-1 in trained subjects compared with 7.4 +/- 1.6 mol.kg-1.min-1 in untrained subjects (P < 0.01) over the first hour and declined to 6.8 +/- 2.8 and 4.9 +/- 1.4 mol.kg-1.min-1 during the second hour. In conclusion, these observations indicate that endurance training is associated with an increase in HGP in response to physiological levels of glucagon, thus suggesting an increase in hepatic glucagon sensitivity.
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Affiliation(s)
- R Drouin
- Research Center, Centre Hospitalier, Université de Montréal, Quebec, Canada
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Rastogi KS, Cooper RL, Shi ZQ, Vranic M. Quantitative measurement of islet glucagon response to hypoglycemia by confocal fluorescence imaging in diabetic rats: effects of phlorizin treatment. Endocrine 1997; 7:367-75. [PMID: 9657075 DOI: 10.1007/bf02801332] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UNLABELLED We have shown that the glucagon irresponsiveness to hypoglycemia in diabetic rats is markedly improved by correction of hyperglycemia independent of insulin. In contrast, normalization of glycemia by insulin did not improve this response. To find out whether these glucagon responses reflect changes in islet glucagon, we directly quantified glucagon area and content in each pancreatic islet by using fluorescent immunostaining and computerized image analysis with confocal laser scanning microscopy (CLSM). The pancreases were analyzed in four groups of rats. 1. Normal controls (NC, n = 4), streptozotocin (65 mg/kg) diabetic rats. 2. Diabetic untreated (DU, n = 4). 3. Diabetic Phlorizin-treated, (0.4 g/kg), twice daily for 4 d (DP, n = 4). 4. Diabetic insulin-treated, using sustained release (2-3 U/d) insulin implant for 5 d (DI, n = 4). Basal plasma glucose was 7.4 +/- 0.3 mM in NC, increased to 14.5 +/- 2.2 mM in DU, which was normalized in DP (5.5 +/- 0.5) and DI (6.7 +/- 0.8). Acute hypoglycemia (H) was induced by i.v. insulin injection. The rats were sacrificed 2 h after insulin injection and the pancreas was removed. By imaging with CLSM, we quantified: 1. Percent of glucagon containing A-cell area/islet area, 2. Fluorescence intensity per islet area, which indicated glucagon content in the islet. 3. Fluorescence intensity per glucagon area indicating glucagon concentration in A-cells. In NC, glucagon containing A cell area was 21 +/- 2% of the islet area, and glucagon intensity and concentration was 11 +/- 1 U and 36 +/- 3.0 U, respectively, in basal (O) state and did not change in (H). In DU, glucagon area increased 183% (O) and 166% (H), and islet glucagon intensity increased by 235% (O) (p < 0.05), but decreased to 135% in H. Glucagon area in DP and DI did not differ significantly from DU. However, hypoglycemia in DP increased glucagon intensity in islet further to 306% of normal control (p < 0.05), suggesting marked increase in glucagon content indicating increased synthesis. In contrast, DI compared to DP showed a decrease in glucagon intensity in islet (46 +/- 3, DP to 22 +/- 2 DI; p < 0.05) in (H) state. Glucagon concentration followed the same pattern as its intensity. CONCLUSION 1. Increase in islet glucagon content in diabetic rats was associated with increase in glucagon containing A-cell area per islet. 2. Phlorizin-induced insulin independent correction of hyperglycemia increased glucagon content per islet in hypoglycemic state. This, in part, probably contributed to improved glucagon response to hypoglycemia observed earlier 3. Normalization of glycemia with insulin reduced glucagon content of each islet during hypoglycemia. This may explain, in part, unresponsiveness of glucagon to hypoglycemia often observed in insulin-dependent diabetes mellitus (IDDM) with intensive insulin therapy.
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Affiliation(s)
- K S Rastogi
- Department of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada
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Abstract
Amylin is a recently discovered 37 amino acid peptide secreted into the bloodstream, along with insulin, from pancreatic beta-cells. It is about 50% identical to calcitonin gene-related peptides (CGRP alpha and CGRP beta) and structurally related to the calcitonins. Amylin can elicit the vasodilator effects of CGRP and the hypocalcaemic actions of calcitonin, while these peptides can mimic newly discovered actions of amylin on carbohydrate metabolism. The different relative potencies of these peptides suggest that they act with different selectivities at a family of receptors. Amylin is deficient in insulin-dependent diabetes mellitus, while plasma levels are elevated in insulin-resistant conditions such as obesity and impaired glucose tolerance. In this Viewpoint article, Tim Rink and colleagues propose that amylin is an endocrine partner to insulin and glucagon; deficiency or excess of amylin may therefore contribute to important metabolic diseases.
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Affiliation(s)
- T J Rink
- Amylin Pharmaceuticals Inc., San Diego, CA 92121
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