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Schopman JE, Hoekstra JBL, Frier BM, Ackermans MT, de Sonnaville JJJ, Stades AM, Zwertbroek R, Hartmann B, Holst JJ, Knop FK, Holleman F. Effects of sitagliptin on counter-regulatory and incretin hormones during acute hypoglycaemia in patients with type 1 diabetes: a randomized double-blind placebo-controlled crossover study. Diabetes Obes Metab 2015; 17:546-553. [PMID: 25694217 DOI: 10.1111/dom.12453] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 02/01/2015] [Accepted: 02/16/2015] [Indexed: 11/26/2022]
Abstract
AIMS To assess whether the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin affects glucagon and other counter-regulatory hormone responses to hypoglycaemia in patients with type 1 diabetes. METHODS We conducted a single-centre, randomized, double-blind, placebo-controlled, three-period crossover study. We studied 16 male patients with type 1 diabetes aged 18-52 years, with a diabetes duration of 5-20 years and intact hypoglycaemia awareness. Participants received sitagliptin (100 mg/day) or placebo for 6 weeks and attended the hospital for three acute hypoglycaemia studies (at baseline, after sitagliptin treatment and after placebo). The primary outcome was differences between the three hypoglycaemia study days with respect to plasma glucagon responses from the initialization phase of the hypoglycaemia intervention to 40 min after onset of the autonomic reaction. RESULTS Sitagliptin treatment significantly increased active levels of glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1. No significant differences were observed for glucagon or adrenergic counter-regulatory responses during the three hypoglycaemia studies. Growth hormone concentration at 40 min after occurrence of autonomic reaction was significantly lower after sitagliptin treatment [median (IQR) 23 (0.2-211.0) mEq/l] compared with placebo [median (IQR) 90 (8.8-180) mEq/l; p = 0.008]. CONCLUSIONS Sitagliptin does not affect glucagon or adrenergic counter-regulatory responses in patients with type 1 diabetes, but attenuates the growth hormone response during late hypoglycaemia.
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Affiliation(s)
- J E Schopman
- Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - J B L Hoekstra
- Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - B M Frier
- Department of Diabetes, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - M T Ackermans
- Department of Clinical Chemistry, Laboratory of Endocrinology and Radiochemistry, Academic Medical Center, Amsterdam, The Netherlands
| | | | - A M Stades
- Department of Internal Medicine, University Medical Center, Utrecht, The Netherlands
| | - R Zwertbroek
- Department of Internal Medicine, Westfriesgasthuis, Hoorn, The Netherlands
| | - B Hartmann
- Department of Biomedical Sciences, NNF Centre for Basic Metabolic Research, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - J J Holst
- Department of Biomedical Sciences, NNF Centre for Basic Metabolic Research, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - F K Knop
- Department of Biomedical Sciences, NNF Centre for Basic Metabolic Research, Panum Institute, University of Copenhagen, Copenhagen, Denmark
- Department of Internal Medicine, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - F Holleman
- Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands
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Justice TD, Hammer GL, Davey RJ, Paramalingam N, Guelfi KJ, Lewis L, Davis EA, Jones TW, Fournier PA. Effect of antecedent moderate-intensity exercise on the glycemia-increasing effect of a 30-sec maximal sprint: a sex comparison. Physiol Rep 2015; 3:3/5/e12386. [PMID: 26019290 PMCID: PMC4463820 DOI: 10.14814/phy2.12386] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
This study investigated whether a prior bout of moderate-intensity exercise attenuates the glycemia-increasing effect of a maximal 30-sec sprint. A secondary aim was to determine whether the effect of antecedent exercise on the glucoregulatory response to sprinting is affected by sex. Participants (men n = 8; women n = 7) were tested on two occasions during which they either rested (CON) or cycled for 60-min at a moderate intensity of ~65% (EX) before performing a 30-sec maximal cycling effort 195 min later. In response to the sprint, blood glucose increased to a similar extent between EX and CON trials, peaking at 10 min of recovery, with no difference between sexes (P > 0.05). Blood glucose then declined at a faster rate in EX, and this was associated with a glucose rate of disappearance (Rd) that exceeded the glucose rate of appearance (Ra) earlier in EX compared with CON, although the overall glucose Ra and Rd profile was higher in men compared with women (P < 0.05). The response of growth hormone was attenuated during recovery from EX compared with CON (P < 0.05), with a lower absolute response in women compared with men (P < 0.05). The response of epinephrine and norepinephrine was also lower in women compared with men (P < 0.05) but similar between trials. In summary, a prior bout of moderate-intensity exercise does not affect the magnitude of the glycemia-increasing response to a 30-sec sprint; however, the subsequent decline in blood glucose is more rapid. This blood glucose response is similar between men and women, despite less pronounced changes in glucose Ra and Rd, and a lower response of plasma catecholamines and growth hormone to sprinting in women.
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Affiliation(s)
- Tara D Justice
- School of Sport Science, Exercise, and Health The University of Western Australia, Crawley, Western Australia, Australia
| | - Greta L Hammer
- School of Sport Science, Exercise, and Health The University of Western Australia, Crawley, Western Australia, Australia
| | - Raymond J Davey
- School of Sport Science, Exercise, and Health The University of Western Australia, Crawley, Western Australia, Australia Telethon Kids Institute The University of Western Australia, Crawley, Western Australia, Australia School of Paediatrics and Child Health The University of Western Australia, Perth, Western Australia, Australia
| | - Nirubasini Paramalingam
- Telethon Kids Institute The University of Western Australia, Crawley, Western Australia, Australia Department of Endocrinology and Diabetes, Princess Margaret Hospital, Perth, Western Australia, Australia
| | - Kym J Guelfi
- School of Sport Science, Exercise, and Health The University of Western Australia, Crawley, Western Australia, Australia
| | - Lynley Lewis
- Department of Medicine, Christchurch Heart Institute The University of Otago, Dunedin, New Zealand
| | - Elizabeth A Davis
- Telethon Kids Institute The University of Western Australia, Crawley, Western Australia, Australia School of Paediatrics and Child Health The University of Western Australia, Perth, Western Australia, Australia Department of Endocrinology and Diabetes, Princess Margaret Hospital, Perth, Western Australia, Australia
| | - Timothy W Jones
- Telethon Kids Institute The University of Western Australia, Crawley, Western Australia, Australia School of Paediatrics and Child Health The University of Western Australia, Perth, Western Australia, Australia Department of Endocrinology and Diabetes, Princess Margaret Hospital, Perth, Western Australia, Australia
| | - Paul A Fournier
- School of Sport Science, Exercise, and Health The University of Western Australia, Crawley, Western Australia, Australia
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Abstract
Type 1 diabetes is a common chronic disease of childhood and one of the most difficult conditions to manage. Advances in insulin formulations and insulin delivery devices have markedly improved the ability to achieve normal glucose homeostasis. However, hypoglycemia remains the primary limiting factor in achieving normoglycemia and is a frequent complication in children with acute gastroenteritis and/or poor oral intake. In situations of impaired carbohydrate intake or absorption, glucagon therapy is the only out-of-hospital treatment option available to families and caregivers. Glucagon is recommended for the treatment of severe hypoglycemia and rapidly increases blood glucose by increasing hepatic glucose production from glycogenolysis. Mini-dose glucagon is a widely utilized off-label treatment for managing mild or impending hypoglycemia and is administered as a small subcutaneous injection. It was initially described for use in children who were unable to tolerate or absorb oral carbohydrates but not in need of advanced medical care. Yet, mini-dose glucagon may be useful in any individual with relative insulin excess. The regimen aims to prevent severe hypoglycemic episodes and is safe, effective, and easily administered by patients and caregivers in the out-of-hospital setting. By empowering patients and their families, this important tool could help to alleviate the physical, psychosocial, and financial burden evolving from impending hypoglycemia.
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Affiliation(s)
- Stephanie T Chung
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda MD, USA
| | - Morey W Haymond
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
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Schmidt SL, Bessesen DH, Stotz S, Peelor FF, Miller BF, Horton TJ. Adrenergic control of lipolysis in women compared with men. J Appl Physiol (1985) 2014; 117:1008-19. [PMID: 25190743 DOI: 10.1152/japplphysiol.00003.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Data suggest women are more sensitive to the lipolytic action of epinephrine compared with men while maintaining similar glucoregulatory effects (Horton et al. J Appl Physiol 107: 200-210, 2009). This study aimed to determine the specific adrenergic receptor(s) that may mediate these sex differences. Lean women (n = 14) and men (n = 16) were studied on 4 nonconsecutive days during the following treatment infusions: saline (S: control), epinephrine [E: mixed β-adrenergic (lipolytic) and α2-adrenergic (antilipolytic) stimulation], epinephrine + phentolamine (E + P: mixed β-adrenergic stimulation only), and terbutaline (T: selective β2-adrenergic stimulation). Tracer infusions of glycerol, palmitate, and glucose were administered to determine systemic lipolysis, free fatty acid (FFA) release, and glucose turnover, respectively. Following basal measurements, substrate and hormone concentrations were measured in all subjects over 90 min of treatment and tracer infusion. Women had greater increases in glycerol and FFA concentrations with all three hormone infusions compared with men (P < 0.01). Glycerol and palmitate rate of appearance (Ra) and rate of disappearance (Rd) per kilogram body weight were greater with E infusion in women compared with men (P < 0.05), whereas no sex differences were observed with other treatments. Glucose concentration and kinetics were not different between sexes with any infusion. In conclusion, these data support the hypothesis that the greater rate of lipolysis in women with infusion of E was likely due to lesser α2 antilipolytic activation. These findings may help explain why women have greater lipolysis and fat oxidation during exercise, a time when epinephrine concentration is elevated.
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Affiliation(s)
- Stacy L Schmidt
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Anschutz Health and Wellness Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado; The Obesity Treatment Foundation, Aurora, Colorado
| | - Daniel H Bessesen
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Anschutz Health and Wellness Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Denver Health Medical Center, Denver, Colorado
| | - Sarah Stotz
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Anschutz Health and Wellness Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Frederick F Peelor
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado; and
| | - Benjamin F Miller
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado; and
| | - Tracy J Horton
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Anschutz Health and Wellness Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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Abstract
Under normal conditions, food intake and energy expenditure are balanced by a homeostatic system that maintains stability of body fat content over time. However, this homeostatic system can be overridden by the activation of 'emergency response circuits' that mediate feeding responses to emergent or stressful stimuli. Inhibition of these circuits is therefore permissive for normal energy homeostasis to occur, and their chronic activation can cause profound, even life-threatening, changes in body fat mass. This Review highlights how the interplay between homeostatic and emergency feeding circuits influences the biologically defended level of body weight under physiological and pathophysiological conditions.
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Affiliation(s)
- Gregory J Morton
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington 98109, USA
| | - Thomas H Meek
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington 98109, USA
| | - Michael W Schwartz
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington 98109, USA
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Mudaliar S, Henry RR, Boden G, Smith S, Chalamandaris AG, Duchesne D, Iqbal N, List J. Changes in insulin sensitivity and insulin secretion with the sodium glucose cotransporter 2 inhibitor dapagliflozin. Diabetes Technol Ther 2014; 16:137-44. [PMID: 24237386 DOI: 10.1089/dia.2013.0167] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AIM This randomized, double-blind, placebo-controlled parallel-group study assessed the effects of sodium glucose cotransporter 2 inhibition by dapagliflozin on insulin sensitivity and secretion in subjects with type 2 diabetes mellitus (T2DM), who had inadequate glycemic control with metformin (with or without an insulin secretagogue). SUBJECTS AND METHODS Forty-four subjects were randomized to receive dapagliflozin 5 mg or matching placebo once daily for 12 weeks. Subjects continued stable doses of background antidiabetes medication throughout the study. Insulin sensitivity was assessed by measuring the glucose disappearance rate (GDR) during the last 40 min of a 5-h hyperinsulinemic, euglycemic clamp. Insulin secretion was determined as the acute insulin response to glucose (AIRg) during the first 10 min of a frequently sampled intravenous glucose tolerance test. Where noted, data were adjusted for baseline values and background antidiabetes medication. RESULTS An adjusted mean increase from baseline in GDR (last observation carried forward), at Week 12, was observed with dapagliflozin (7.98%) versus a decrease with placebo (-9.99%). The 19.97% (95% confidence interval 5.75-36.10) difference in GDR versus placebo was statistically significant (P=0.0059). A change from baseline in adjusted mean AIRg of 15.39 mU/L min was observed with dapagliflozin at Week 12, versus -12.73 mU/L min with placebo (P=0.0598). Over 12 weeks, numerical reductions from baseline in glycosylated hemoglobin (HbA1c), fasting plasma glucose, and body weight were observed with dapagliflozin (-0.38%, -0.39 mmol/L, and -1.58%, respectively) versus slight numerical increases with placebo (0.03%, 0.26 mmol/L, and 0.62%, respectively). CONCLUSIONS In patients with T2DM and inadequate glycemic control, dapagliflozin treatment improved insulin sensitivity in the setting of reductions in HbA1c and weight.
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Affiliation(s)
- Sunder Mudaliar
- 1 Center for Metabolic Research, VA San Diego Healthcare System, and University of California , San Diego, San Diego, California
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57
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Little SA, Leelarathna L, Barendse SM, Walkinshaw E, Tan HK, Lubina Solomon A, de Zoysa N, Rogers H, Choudhary P, Amiel SA, Heller SR, Evans M, Flanagan D, Speight J, Shaw JAM. Severe hypoglycaemia in type 1 diabetes mellitus: underlying drivers and potential strategies for successful prevention. Diabetes Metab Res Rev 2014; 30:175-90. [PMID: 24185859 DOI: 10.1002/dmrr.2492] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Revised: 10/23/2013] [Accepted: 10/25/2013] [Indexed: 02/03/2023]
Abstract
Hypoglycaemia remains an over-riding factor limiting optimal glycaemic control in type 1 diabetes. Severe hypoglycaemia is prevalent in almost half of those with long-duration diabetes and is one of the most feared diabetes-related complications. In this review, we present an overview of the increasing body of literature seeking to elucidate the underlying pathophysiology of severe hypoglycaemia and the limited evidence behind the strategies employed to prevent episodes. Drivers of severe hypoglycaemia including impaired counter-regulation, hypoglycaemia-associated autonomic failure, psychosocial and behavioural factors and neuroimaging correlates are discussed. Treatment strategies encompassing structured education, insulin analogue regimens, continuous subcutaneous insulin infusion pumps, continuous glucose sensing and beta-cell replacement therapies have been employed, yet there is little randomized controlled trial evidence demonstrating effectiveness of new technologies in reducing severe hypoglycaemia. Optimally designed interventional trials evaluating these existing technologies and using modern methods of teaching patients flexible insulin use within structured education programmes with the specific goal of preventing severe hypoglycaemia are required. Individuals at high risk need to be monitored with meticulous collection of data on awareness, as well as frequency and severity of all hypoglycaemic episodes.
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Affiliation(s)
- S A Little
- Institute of Cellular Medicine, Newcastle University, Newcastle, UK
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58
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Tao YX, Liang XF. G Protein-Coupled Receptors as Regulators of Glucose Homeostasis and Therapeutic Targets for Diabetes Mellitus. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 121:1-21. [DOI: 10.1016/b978-0-12-800101-1.00001-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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59
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Abstract
Hypoglycemia remains a common problem for patients with diabetes and is associated with substantial morbidity and mortality. This article summarizes our current knowledge of the epidemiology, pathogenesis, risk factors, and complications of hypoglycemia in patients with diabetes and discusses prevention and treatment strategies.
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Affiliation(s)
- Mazen Alsahli
- Division of Endocrinology, Department of Medicine, Southlake Regional Health Center, 309-531 Davis Drive, Newmarket, Ontario L3Y 6P5, Canada; Faculty of Medicine, Department of Medicine, University of Toronto, 1 King's College Cir, Toronto, Ontario M5S 1A8, Canada
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60
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Abstract
Physical exercise is firmly incorporated in the management of type 1 diabetes (T1DM), due to multiple recognized beneficial health effects (cardiovascular disease prevention being preeminent). When glycemic values are not excessively low or high at the time of exercise, few absolute contraindications exist; practical guidelines regarding amount, type, and duration of age-appropriate exercise are regularly updated by entities such as the American Diabetes Association and the International Society for Pediatric and Adolescent Diabetes. Practical implementation of exercise regimens, however, may at times be problematic. In the poorly controlled patient, specific structural changes may occur within skeletal muscle fiber, which is considered by some to be a disease-specific myopathy. Further, even in well-controlled patients, several homeostatic mechanisms regulating carbohydrate metabolism often become impaired, causing hypo- or hyperglycemia during and/or after exercise. Some altered responses may be related to inappropriate exogenous insulin administration, but are often also partly caused by the "metabolic memory" of prior glycemic events. In this context, prior hyperglycemia correlates with increased inflammatory and oxidative stress responses, possibly modulating key exercise-associated cardio-protective pathways. Similarly, prior hypoglycemia correlates with impaired glucose counterregulation, resulting in greater likelihood of further hypoglycemia to develop. Additional exercise responses that may be altered in T1DM include growth factor release, which may be especially important in children and adolescents. These multiple alterations in the exercise response should not discourage physical activity in patients with T1DM, but rather should stimulate the quest for the identification of the exercise formats that maximize beneficial health effects.
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Affiliation(s)
- Pietro Galassetti
- Department of Pediatrics, University of California Irvine, Irvine, California, USA.
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61
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Szepietowska B, Zhu W, Sherwin RS. β2-Adrenergic receptor agonist administration promotes counter-regulatory responses and recovery from hypoglycaemia in rats. Diabetologia 2013; 56:2517-23. [PMID: 23933834 PMCID: PMC3857969 DOI: 10.1007/s00125-013-3009-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 07/10/2013] [Indexed: 01/22/2023]
Abstract
AIMS/HYPOTHESIS We have previously reported that local activation of β2-adrenergic receptors (B2ARs) in the ventromedial hypothalamus (VMH) enhances hypoglycaemic counter-regulation. This study examines whether peripheral delivery of a selective B2AR agonist could also promote counter-regulatory responses and thereby has potential therapeutic value to limit hypoglycaemia risk. METHODS Conscious male Sprague-Dawley rats received an intra-arterial injection of the B2AR specific agonist, formoterol, or a control solution either before a hyperinsulinaemic-hypoglycaemic clamp study or immediately before recovery from insulin-induced hypoglycaemia. In addition, the capacity of a VMH-targeted microinjection of a B2AR antagonist to limit the anti-insulin effect of the B2AR agonist was assessed. RESULTS Systemic delivery of B2AR agonist markedly reduced the exogenous glucose infusion rate (GIR) required during the hypoglycaemic clamp study. This effect was mediated by blockade of insulin's inhibitory effect on endogenous glucose production. Local blockade of B2ARs within the VMH using a specific antagonist partially diminished the effect of systemic activation of B2ARs during hypoglycaemia at least in part by diminishing the adrenaline (epinephrine) response to hypoglycaemia. Peripheral B2AR agonist injection also enhanced glucose recovery from insulin-induced hypoglycaemia. CONCLUSIONS/INTERPRETATION Systemic B2AR agonist administration acts to limit insulin-induced hypoglycaemia by offsetting insulin's inhibitory effect on hepatic glucose production. This effect appears to be predominately mediated via a direct effect on liver B2ARs, but a small stimulatory effect on B2ARs within the VMH cannot be excluded. Our data suggest that formoterol may have therapeutic value to limit the risk of hypoglycaemia in patients with diabetes.
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Affiliation(s)
- Barbara Szepietowska
- Section of Endocrinology, Yale University School of Medicine, 300 Cedar St, TAC S141, New Haven, CT, 06520, USA
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62
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Yue JT, Riddell MC, Burdett E, Coy DH, Efendic S, Vranic M. Amelioration of hypoglycemia via somatostatin receptor type 2 antagonism in recurrently hypoglycemic diabetic rats. Diabetes 2013; 62:2215-22. [PMID: 23434929 PMCID: PMC3712070 DOI: 10.2337/db12-1523] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Selective antagonism of somatostatin receptor type 2 (SSTR2) normalizes glucagon and corticosterone responses to hypoglycemic clamp in diabetic rats. The purpose of this study was to determine whether SSTR2 antagonism (SSTR2a) ameliorates hypoglycemia in response to overinsulinization in diabetic rats previously exposed to recurrent hypoglycemia. Streptozotocin diabetic rats (n = 19), previously subjected to five hypoglycemia events over 3 days, received an insulin bolus (10 units/kg i.v.) plus insulin infusion (50 mU/kg/min i.v.) until hypoglycemia ensued (≤3.9 mmol/L) (experimental day 1 [Expt-D1]). The next day (Expt-D2), rats were allocated to receive either placebo treatment (n = 7) or SSTR2a infusion (3,000 nmol/kg/min i.v., n = 12) 60 min prior to the same insulin regimen. On Expt-D1, all rats developed hypoglycemia by ∼90 min, while on Expt-D2, hypoglycemia was attenuated with SSTR2a treatment (nadir = 3.7 ± 0.3 vs. 2.7 ± 0.3 mmol/L in SSTR2a and controls, P < 0.01). Glucagon response to hypoglycemia on Expt-D2 deteriorated by 20-fold in the placebo group (P < 0.001) but improved in the SSTR2a group (threefold increase in area under the curve [AUC], P < 0.001). Corticosterone response deteriorated in the placebo-treated rats on Expt-D2 but increased twofold in the SSTR2a group. Catecholamine responses were not affected by SSTR2a. Thus, SSTR2 antagonism after recurrent hypoglycemia improves the glucagon and corticosterone responses and largely ameliorates insulin-induced hypoglycemia in diabetic rats.
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Affiliation(s)
- Jessica T.Y. Yue
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Michael C. Riddell
- School of Kinesiology and Health Science, Faculty of Health, York University, Toronto, Ontario, Canada
- Corresponding authors: Michael C. Riddell, , and Mladen Vranic,
| | - Elena Burdett
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - David H. Coy
- Department of Medicine, Peptide Research Laboratories, Tulane University, New Orleans, Louisiana
| | - Suad Efendic
- Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Mladen Vranic
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Corresponding authors: Michael C. Riddell, , and Mladen Vranic,
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63
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Guerci B, Kuhn JM, Larger É, Reznik Y. Hypoglycaemia in adults: when should it be raised? How can hypoglycaemia be confirmed in non-diabetic adults? ANNALES D'ENDOCRINOLOGIE 2013; 74:168-73. [PMID: 23791454 DOI: 10.1016/j.ando.2013.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Bruno Guerci
- Department of diabetology, metabolic and nutritional diseases, Jeanne-d'Arc hospital, university hospital of Nancy, BP 90303, 54201 Toul, France.
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Quantifying the contribution of the liver to glucose homeostasis: a detailed kinetic model of human hepatic glucose metabolism. PLoS Comput Biol 2012; 8:e1002577. [PMID: 22761565 PMCID: PMC3383054 DOI: 10.1371/journal.pcbi.1002577] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 05/08/2012] [Indexed: 02/02/2023] Open
Abstract
Despite the crucial role of the liver in glucose homeostasis, a detailed mathematical model of human hepatic glucose metabolism is lacking so far. Here we present a detailed kinetic model of glycolysis, gluconeogenesis and glycogen metabolism in human hepatocytes integrated with the hormonal control of these pathways by insulin, glucagon and epinephrine. Model simulations are in good agreement with experimental data on (i) the quantitative contributions of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization under varying physiological states. (ii) the time courses of postprandial glycogen storage as well as glycogen depletion in overnight fasting and short term fasting (iii) the switch from net hepatic glucose production under hypoglycemia to net hepatic glucose utilization under hyperglycemia essential for glucose homeostasis (iv) hormone perturbations of hepatic glucose metabolism. Response analysis reveals an extra high capacity of the liver to counteract changes of plasma glucose level below 5 mM (hypoglycemia) and above 7.5 mM (hyperglycemia). Our model may serve as an important module of a whole-body model of human glucose metabolism and as a valuable tool for understanding the role of the liver in glucose homeostasis under normal conditions and in diseases like diabetes or glycogen storage diseases.
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65
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Cryer PE. Minireview: Glucagon in the pathogenesis of hypoglycemia and hyperglycemia in diabetes. Endocrinology 2012; 153:1039-48. [PMID: 22166985 PMCID: PMC3281526 DOI: 10.1210/en.2011-1499] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 11/22/2011] [Indexed: 01/22/2023]
Abstract
Pancreatic islet α-cell glucagon secretion is critically dependent on pancreatic islet β-cell insulin secretion. Normally, a decrease in the plasma glucose concentration causes a decrease in β-cell insulin secretion that signals an increase in α-cell glucagon secretion during hypoglycemia. In contrast, an increase in the plasma glucose concentration, among other stimuli, causes an increase in β-cell insulin secretion that signals a decrease, or at least no change, in α-cell glucagon secretion after a meal. In absolute endogenous insulin deficiency (i.e. in type 1 diabetes and in advanced type 2 diabetes), however, β-cell failure results in no decrease in β-cell insulin secretion and thus no increase in α-cell glucagon secretion during hypoglycemia and no increase in β-cell insulin secretion and thus an increase in α-cell glucagon secretion after a meal. In type 1 diabetes and advanced type 2 diabetes, the absence of an increment in glucagon secretion, in the setting of an absent decrement in insulin secretion and an attenuated increment in sympathoadrenal activity, in response to falling plasma glucose concentrations plays a key role in the pathogenesis of iatrogenic hypoglycemia. In addition, there is increasing evidence that, in the aggregate, suggests that relative hyperglucagonemia, in the setting of deficient insulin secretion, plays a role in the pathogenesis of hyperglycemia in diabetes. If so, abnormal glucagon secretion is involved in the pathogenesis of both hypoglycemia and hyperglycemia in diabetes.
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Affiliation(s)
- Philip E Cryer
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University, St. Louis, Missouri 63110, USA.
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66
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Alghothani N, Dungan KM. The effect of glycemic variability on counterregulatory hormone responses to hypoglycemia in young children and adolescents with type 1 diabetes. Diabetes Technol Ther 2011; 13:1085-9. [PMID: 21770764 PMCID: PMC3202890 DOI: 10.1089/dia.2011.0026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Glycemic variability (GV) is associated with hypoglycemia and possibly diabetes-related outcomes. We hypothesized that GV and glucose excursion risk may predict counterregulatory (CR) hormone responses to hypoglycemia. RESEARCH DESIGN AND METHODS This is a secondary analysis of a Diabetes Research in Children Network study containing continuous interstitial glucose monitoring records for 28 patients with type 1 diabetes between 3 to <8 or 12 to <18 years of age. GV and excursion measures, including continuous overall net glycemic action (CONGA), High Blood Glucose Index (HBGI), Low Blood Glucose Index (LBGI), and coefficient of variation (CV), were calculated 72 h prior to insulin-induced hypoglycemia. CR hormones were measured during the progressive fall in plasma glucose. RESULTS CV was inversely correlated with change in glucagon concentration (r=-0.41, P=0.046), but CONGA (log-transformed for better fit of the models) was not statistically significant in univariate analysis (r=-0.34, P=0.10). Other CR hormones were not significantly associated with measures of variability. In multivariate analysis, higher CONGA, but not CV, was associated with a smaller rise in glucagon following induced hypoglycemia (estimate=-9.73, P=0.048), independent of hemoglobin A1c, duration of diabetes, and insulin dose. HBGI, LBGI, and antecedent time spent in hypoglycemia were not significantly correlated with CR response to subsequent hypoglycemia. CONCLUSIONS CV and CONGA may be predictors of impaired glucagon responses to insulin-induced hypoglycemia in patients with type 1 diabetes. Further study is indicated to characterize the role of GV and glycemic excursions on the defensive response to hypoglycemia.
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Affiliation(s)
- Nora Alghothani
- Department of Internal Medicine, Mount Carmel Health System, Columbus, Ohio
| | - Kathleen M. Dungan
- Division of Endocrinology, Diabetes and Metabolism, The Ohio State University, Columbus, Ohio
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67
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Sprague JE, Arbeláez AM. Glucose counterregulatory responses to hypoglycemia. PEDIATRIC ENDOCRINOLOGY REVIEWS : PER 2011; 9:463-73; quiz 474-5. [PMID: 22783644 PMCID: PMC3755377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The brain relies almost exclusively on glucose for fuel. Therefore, adequate uptake of glucose from the plasma is key for normal brain function and survival. Despite wide variations in glucose flux (i.e., fed state, fasting state, etc), blood glucose is maintained in a very narrow range. This is accomplished by a series of hormonal and physiologic responses. As a result, hypoglycemia is a rare occurrence in normal individuals. However, glucose counterregulatory responses are altered in patients with diabetes treated with insulin especially after repeated hypoglycemia or antecedent exercise.
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Affiliation(s)
- Jennifer E Sprague
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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68
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Woods SC, Taborsky GJ, Porte D. Central Nervous System Control of Nutrient Homeostasis. Compr Physiol 2011. [DOI: 10.1002/cphy.cp010407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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69
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Abstract
The counterregulatory response to hypoglycemia is a complex and well-coordinated process. As blood glucose concentration declines, peripheral and central glucose sensors relay this information to central integrative centers to coordinate neuroendocrine, autonomic, and behavioral responses and avert the progression of hypoglycemia. Diabetes, both type 1 and type 2, can perturb these counterregulatory responses. Moreover, defective counterregulation in the setting of diabetes can progress to hypoglycemia unawareness. While the mechanisms that underlie the development of hypoglycemia unawareness are not completely known, possible causes include altered sensing of hypoglycemia by the brain and/or impaired coordination of responses to hypoglycemia. Further study is needed to better understand the intricacies of the counterregulatory response and the mechanisms contributing to the development of hypoglycemia unawareness.
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Affiliation(s)
- Nolawit Tesfaye
- Department of Medicine, Division of Endocrinology and Diabetes, University of Minnesota, 420 Delaware St. SE, Minneapolis, MN 55455, USA
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71
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Lechin F, van der Dijs B, Pardey-Maldonado B, Rivera JE, Lechin ME, Baez S. Amantadine reduces glucagon and enhances insulin secretion throughout the oral glucose tolerance test: central plus peripheral nervous system mechanisms. Diabetes Metab Syndr Obes 2009; 2:203-13. [PMID: 21437134 PMCID: PMC3048001 DOI: 10.2147/dmsott.s7606] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
OBJECTIVE The purpose of the trial was to examine the effects of amantadine, a N-methyl-D-aspartate (NMDA) antagonist, on the oral glucose tolerance test (OGTT) plus insulin, glucagon and neurotransmitters circulating levels. Previous findings showed that hyperinsulinism and type 2 diabetes are positively associated with neural sympathetic and adrenal sympathetic activities, respectively. These peripheral sympathetic branches depend on the pontine (A(5)-noradrenergic) and the rostral ventrolateral (C(1)-adrenergic) medullary nuclei. They are excited by glutamate axons which act at NMDA postsynaptic receptors. RESEARCH DESIGN AND METHODS One OGTT plus placebo and one OGTT plus oral amantadine test were carried out two weeks apart in 15 caucasic normal voluntary humans. Noradrenaline, adrenaline, dopamine, plasma-free serotonin, platelet serotonin, glucose, glucagon, and insulin were measured throughout the 180-minute testing period. RESULTS Maximal reductions of plasma glucose and glucagon plus exacerbated insulin rises were significantly greater throughout the oral glucose plus amantadine test than those registered throughout the oral glucose plus placebo challenge. The above findings were paralleled by greater than normal noradrenaline/adrenaline plasma ratio increases. In addition, maximal reductions of the platelet serotonin and plasma serotonin circulating values contrasted with the normal rises of these parameters, always registered during the glucose load plus placebo challenge. CONCLUSION This study supports the theory that amantadine might be a powerful antidiabetic tool and could be added to the therapeutic arsenal against type 2 diabetes.
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Affiliation(s)
- Fuad Lechin
- Department of Physiological Sciences, Sections of Neuroendocrinology, Neuropharmacology, and Neurochemistry, Instituto de Medicina Experimental, Faculty of Medicine, Universidad Central de Venezuela, Caracas, Venezuela
| | - Bertha van der Dijs
- Department of Physiological Sciences, Sections of Neuroendocrinology, Neuropharmacology, and Neurochemistry, Instituto de Medicina Experimental, Faculty of Medicine, Universidad Central de Venezuela, Caracas, Venezuela
| | - Betty Pardey-Maldonado
- Department of Physiological Sciences, Sections of Neuroendocrinology, Neuropharmacology, and Neurochemistry, Instituto de Medicina Experimental, Faculty of Medicine, Universidad Central de Venezuela, Caracas, Venezuela
| | - Jairo E Rivera
- Department of Physiological Sciences, Sections of Neuroendocrinology, Neuropharmacology, and Neurochemistry, Instituto de Medicina Experimental, Faculty of Medicine, Universidad Central de Venezuela, Caracas, Venezuela
| | - Marcel E Lechin
- Department of Internal Medicine, Texas A & M Health Science Center, College of Medicine, TX, USA
| | - Scarlet Baez
- Department of Physiological Sciences, Sections of Neuroendocrinology, Neuropharmacology, and Neurochemistry, Instituto de Medicina Experimental, Faculty of Medicine, Universidad Central de Venezuela, Caracas, Venezuela
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72
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Correction for the effect of rising plasma glucose levels on quantification of MR(glc) with FDG-PET. J Cereb Blood Flow Metab 2009; 29:1059-67. [PMID: 19293824 DOI: 10.1038/jcbfm.2009.21] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Positron emission tomography (PET) using the tracer [18F]-fluorodeoxyglucose (FDG) is commonly used for measuring metabolic rate of glucose (MR(glc)) in the human brain. Conventional PET methods (e.g., the Patlak method) for quantifying MR(glc) assume the tissue transport and phosphorylation mechanisms to be in steady state during FDG uptake. As FDG and glucose use the same transporters and phosphorylation enzymes, changing blood glucose levels can change the rates of FDG transport and phosphorylation. Compartmental models were used to simulate the effect of rising arterial glucose, from normal to hyperglycemic levels on FDG uptake for a typical PET protocol. The subsequent errors on the values of MR(glc) calculated using the Patlak method were investigated, and a correction scheme based on measured arterial glucose concentration (G(p)) was evaluated. Typically, with a 40% rise in G(p) over the duration of the PET study, the true MR(glc) varied by only 1%; however, the Patlak method overestimated MR(glc) by 15%. The application of the correction reduced this error to approximately 2%. In general, the application of the correction resulted in values of MR(glc) consistently significantly closer to the true steady state calculation of MR(glc) independently of changes to the parameters defining the model.
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73
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Horton TJ, Dow S, Armstrong M, Donahoo WT. Greater systemic lipolysis in women compared with men during moderate-dose infusion of epinephrine and/or norepinephrine. J Appl Physiol (1985) 2009; 107:200-10. [PMID: 19407251 DOI: 10.1152/japplphysiol.90812.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Women have lower circulating catecholamine levels during metabolic perturbations, such as exercise or hypoglycemia, but similar rates of systemic lipolysis. This suggests women may be more sensitive to the lipolytic action of catecholamines, while maintaining similar glucoregulatory effects. The aim of the present study, therefore, was to determine whether women have higher rates of systemic lipolysis compared with men in response to matched peripheral infusion of catecholamines, but similar rates of glucose turnover. Healthy, nonobese women (n = 11) and men (n = 10) were recruited and studied on 3 separate days with the following infusions: epinephrine (Epi), norepinephrine (NE), or the two combined. Tracer infusions of glycerol and glucose were used to determine systemic lipolysis and glucose turnover, respectively. Following basal measurements of substrate kinetics, the catecholamine infusion commenced, and measures of substrate kinetics continued for 60 min. Catecholamine concentrations were similarly elevated in women and men during each infusion: Epi, 182-197 pg/ml and NE, 417-507 pg/ml. There was a significant sex difference in glycerol rate of appearance and rate of disappearance with the catecholamine infusions (P < 0.0001), mainly due to a significantly greater glycerol turnover during the first 30 min of each infusion: glycerol rate of appearance during Epi was only 268 +/- 18 vs. 206 +/- 21 micromol/min in women and men, respectively; during NE, only 173 +/- 13 vs. 153 +/- 17 micromol/min, and during Epi+NE, 303 +/- 24 vs. 257 +/- 21 micromol/min. No sex differences were observed in glucose kinetics under any condition. In conclusion, these data suggest that women are more sensitive to the lipolytic action of catecholamines, but have no difference in their glucoregulatory response. Thus the lower catcholamine levels observed in women vs. men during exercise and other metabolic perturbations may allow women to maintain a similar or greater level of lipid mobilization while minimizing changes in glucose turnover.
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Affiliation(s)
- Tracy J Horton
- Section of Nutrition, Dept. of Pediatrics, Univ. of Colorado Denver, Campus Box C225, 12700 East 19th Ave., Aurora, CO 80045, USA.
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Lins PE, Adamson U, Clausen N, Hamberger B, Efendić S. The role of glucagon, catecholamines and cortisol in counterregulation of insulin-induced hypoglycemia in normal man. ACTA MEDICA SCANDINAVICA 2009; 220:39-46. [PMID: 2876589 DOI: 10.1111/j.0954-6820.1986.tb02728.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
To study the response of glucose counterregulation to insulin-induced hypoglycemia, six normals were given a 4-hour infusion of insulin (2.4 U/h) +/- somatostatin (50 micrograms/h). Supplementary glucagon (1.5 or 3.0 ng/kg/min) was given in additional experiments. In a separate study, glucagon was supplemented for 4 hours as a constant rate infusion (3.25 ng/kg/min) or at rates stepwise increasing from 1.5 to 5.0 ng/kg/min. Insulin decreased blood glucose by 1.5 mmol/l and simultaneous suppression of glucagon resulted in a more pronounced hypoglycemia enhancing the adrenaline and cortisol responses. The hyperglycemic effect of glucagon substitution (3 ng/kg/min) faded out after about 2 hours, whereafter exaggerated adrenaline and cortisol responses to hypoglycemia were seen. A comparison between the effects of steady state hyperglucagonemia and gradually appearing hyperglucagonemia on the counterregulation of hypoglycemia revealed no significant differences in glucose, adrenaline and cortisol responses to insulin. It is concluded that the glycemic effect of glucagon is transient in the hypoglycemic state. When the hepatic responsiveness to this hormone is decreased during hypoglycemia, adrenaline becomes the essential protective factor.
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75
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Abstract
The metabolic effects of beta-adrenoceptor blocking agents during hypoglycaemia in patients prone to hypoglycaemia are of interest as diabetics are often treated with these drugs because of hypertension or angina pectoris. Compared with non-diabetics these patients also have impaired glucose compensation after hypoglycaemia, partly secondary to deficient release of glucagon. This makes the diabetics more dependent on adrenergic mechanisms to recover from low blood glucose concentrations. Non-selective beta-adrenoceptor blockade (propranolol) significantly impairs the glucose recovery rate after hypoglycaemia in insulin dependent diabetics, whereas selective beta-adrenoceptor blockade (metoprolol) does not have this side effect. The mechanism of the effect of propranolol is probably an attenuation of the gluconeogenesis secondary to deficient release of the important gluconeogenic substrates lactate and glycerol.
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76
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Kollind M, Adamson U, Lins PE, Curstedt T. Importance of growth hormone for blood glucose regulation following insulin-induced nocturnal hypoglycemia in insulin-dependent diabetes mellitus. ACTA MEDICA SCANDINAVICA 2009; 223:159-64. [PMID: 2894751 DOI: 10.1111/j.0954-6820.1988.tb15781.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of growth hormone (GH) on the glucose homeostasis following nocturnal hypoglycemia was studied between 4 a.m. and noon in eight male patients with insulin-dependent diabetes mellitus (IDDM) by a somatostatin (250 micrograms/h)-insulin (0.4 mU/kg/min)-glucose (6 mg/kg/min)-infusion test (SIGIT). The patients participated in two experiments in which hypoglycemia at 4 a.m. was induced by i.v. insulin (1.5 mU/kg/min). In both experiments the endogenous secretion of GH was suppressed by somatostatin (250 micrograms/h) and glucagon (0.5 ng/kg/min) was given as substitute for the somatostatin-induced suppression of endogenous glucagon secretion. GH (20 mU/kg/h) or saline was given for 60 min from nadir blood glucose in random order. Mean nadir glucose values were the same in both studies (1.7 +/- 0.2 vs. 1.7 +/- 0.1 mmol/l) and no differences were registered in plasma-free insulin, glucagon and the responses of adrenaline and cortisol to hypoglycemia. The infusion of GH resulted in plasma GH levels of about 50 micrograms/l at the end of the infusion, thereafter decreasing to low or immeasurable levels within 2 hours. Infusion of GH evoked a marked hyperglycemia within 4 hours. It is concluded that when hypoglycemia is accompanied by a transient increase in plasma GH, insulin resistance occurs after a lag period of approximately 4 hours and that this effect persists for at least another 4 hours.
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Affiliation(s)
- M Kollind
- Department of Internal Medicine, Danderyd Hospital, Stockholm, Sweden
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77
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Lins PE, Clausen N, Adamson U, Kollind M, Hamberger B, Efendic S. Effect of improved glycemic control by continuous subcutaneous insulin infusion on hormonal responses to insulin-induced hypoglycemia in type 1 diabetics. ACTA MEDICA SCANDINAVICA 2009; 218:111-8. [PMID: 4050545 DOI: 10.1111/j.0954-6820.1985.tb08833.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Glucose counter-regulatory capacity and the hormonal responses to insulin-induced hypoglycemia were studied in eight type 1 diabetics before and after improvement of metabolic control by continuous subcutaneous insulin infusion (CSII). The intensified treatment resulted in a decrease in mean glycosylated hemoglobin from 11.6 +/- 0.5 to 9.3 +/- 0.4% within a mean period of 14 weeks. During a constant rate infusion of insulin (2.4 U/h), steady state levels of glucose appeared in all subjects. The steady state glucose level was identical before and after CSII. The counter-regulatory hormonal responses showed significantly higher epinephrine levels, while glucagon, growth hormone, and cortisol were not influenced. In parallel with the heightened epinephrine response the pulse rate response was significantly enhanced. The restitution of blood glucose after insulin hypoglycemia was not modified. It is concluded that a more vigorous catecholaminergic response to hypoglycemia is achieved after improved metabolic control by CSII.
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78
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Clausen-Sjöbom N, Lins PE, Adamson U, Curstedt T, Hamberger B. Effects of metoprolol on the counter-regulation and recognition of prolonged hypoglycemia in insulin-dependent diabetics. ACTA MEDICA SCANDINAVICA 2009; 222:57-63. [PMID: 3307308 DOI: 10.1111/j.0954-6820.1987.tb09929.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The effect of metoprolol on the counter-regulation of prolonged hypoglycemia was studied in eight insulin-dependent diabetics. Insulin was given as an i.v. infusion of 2.4 U/h over 180 min alone, or together with metoprolol (3.0 mg i.v. bolus followed by an i.v. infusion of 4.8 mg/h) in random order. Blood glucose, counter-regulatory hormones, hypoglycemic symptoms and the cardiovascular responses were assayed over 240 min. Metoprolol did not significantly modify the blood glucose levels. The plasma levels of free insulin, however, were elevated by approximately 20% (p less than 0.01) by metoprolol during hypoglycemia and the plasma concentrations of epinephrine, norepinephrine, growth hormone and cortisol were enhanced by the drug. Sweating was increased by metoprolol, while other symptoms were unaltered. We conclude that metoprolol administered acutely does not aggravate prolonged hypoglycemia in diabetics with blunted response of glucagon. Moreover, exaggerated responses of counter-regulatory hormones, provoked by metoprolol, may compensate for the inhibitory effect of this drug on insulin clearance.
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79
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Adamson U, Efendic S, Lins PE, Wajngot A. Effect of somatostatin on insulin-induced hypoglycemia in man. ACTA MEDICA SCANDINAVICA 2009; 212:33-7. [PMID: 6126999 DOI: 10.1111/j.0954-6820.1982.tb03165.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In order to study the interaction of insulin and somatostatin on glucose regulation in the posthypoglycemic phase of a somatostatin infusion we have applied a bolus of i.v. insulin to healthy subjects receiving a continuous infusion of somatostatin. Glucose, insulin and counterregulatory hormones were determined. Somatostatin suppressed the growth hormone and glucagon responses to hypoglycemia but did not augment the hypoglycemic action of insulin. In contrast, the K-value for the decrease in blood glucose was significantly lower in the presence of somatostatin. Thus, the interaction of insulin and somatostatin on glucose metabolism is complex and time-dependent. While the peptide potentiates the action of insulin during the first hour of somatostatin infusion, it counteracts if after two hours. As somatostatin has currently been introduced in the therapy of upper gastrointestinal bleedings, these effects of the peptide must be taken into consideration.
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80
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Lee SI, Oh SH, Park KY, Park BH, Kim JS, Kim SD. Antihyperglycemic effects of fruits of privet (Ligustrum obtusifolium) in streptozotocin-induced diabetic rats fed a high fat diet. J Med Food 2009; 12:109-17. [PMID: 19298203 DOI: 10.1089/jmf.2007.0000] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The protective effects of freeze-dried privet (Ligustrum obtusifolium) fruits (PFs) were observed in streptozotocin (STZ)-induced diabetic rats on a high fat diet by measuring levels of blood glucose, serum insulin, fructosamine, and hepatic reactive oxygen species generating and scavenging enzyme activities. A PF-supplemented diet was prepared by mixing an AIN-76 diet with powdered PF (final concentration, 1% or 2%). It was fed to STZ-induced diabetic rats on a high fat diet for 6 weeks. Diabetic animals receiving the PF-supplemented diet showed a significant increase in body weight, feed efficiency ratio, liver, kidney, and heart weight, and serum glucose, insulin, and fructosamine levels compared with high fat diet-fed diabetic animals. The treatment with PF showed improved hepatic glutathione S-transferase, superoxide dismutase, and xanthine oxidase activities as well as glutathione and lipid peroxide levels in the diabetic animals. Intracellular swelling and vacuole formation in diabetic pancreatic beta- and delta-cells were ameliorated by the PF-supplemented diet. Furthermore, necrosis of tubular epithelial cells and dilatation of luminal space in diabetic kidneys exhibited near-noninjured condition. This is the first time an antihyperglycemic effect of L. obtusifolium fruit in STZ-induced diabetic rats has been identified.
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Affiliation(s)
- Sang-Il Lee
- Department of Food, Nutrition and Cookery, Keimyung College, Daegu, Republic of Korea
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81
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Sharma R, Vikram NK, Misra A. Comparison of short insulin tolerance test with HOMA Method for assessment of insulin sensitivity in Asian Indians in north India. Diabetes Res Clin Pract 2008; 82:e9-12. [PMID: 18706731 DOI: 10.1016/j.diabres.2008.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 06/20/2008] [Accepted: 07/01/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND Cost-effective method to assess insulin resistance is needed for Asian Indians. METHODS We compared HOMA with SITT methods in 40 subjects. RESULTS Values obtained from both methods did not show any correlation. CONCLUSIONS Both methods should be evaluated against hyperinsulinemic clamp to determine suitability in Asian Indians.
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Affiliation(s)
- Rajeev Sharma
- Department of Internal Medicine, All India Institute of Medical Sciences, New Delhi 110029, India
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82
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Abstract
Mild symptoms of hypoglycemia in individuals with type 1 diabetes who have undergone pancreas transplantation are common, but biochemical evidence of hypoglycemia in these individuals often remains scant. Rarely, more overt cases with profound neuroglycopenic symptoms and documented hypoglycemia after transplantation have been described. Although the diagnosis of hypoglycemia in most cases of adrenergic symptoms alone, without documented hypoglycemia, remains questionable and likely not clinically significant, several potential etiologies have been identified in the more severe cases. This article reports a case with severe hypoglycemia after pancreas transplantation for type 1 diabetes, reviews several potential mechanisms underlying pancreas allograft-associated hypoglycemia, and discusses current treatment strategies for minimizing symptomatic hypoglycemia after transplant.
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Affiliation(s)
- Joy Shen
- Harvard Medical School, Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA
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83
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Cabrera O, Jacques-Silva MC, Speier S, Yang SN, Köhler M, Fachado A, Vieira E, Zierath JR, Kibbey R, Berman DM, Kenyon NS, Ricordi C, Caicedo A, Berggren PO. Glutamate is a positive autocrine signal for glucagon release. Cell Metab 2008; 7:545-54. [PMID: 18522835 PMCID: PMC4396785 DOI: 10.1016/j.cmet.2008.03.004] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Revised: 01/09/2008] [Accepted: 03/10/2008] [Indexed: 11/15/2022]
Abstract
An important feature of glucose homeostasis is the effective release of glucagon from the pancreatic alpha cell. The molecular mechanisms regulating glucagon secretion are still poorly understood. We now demonstrate that human alpha cells express ionotropic glutamate receptors (iGluRs) that are essential for glucagon release. A lowering in glucose concentration results in the release of glutamate from the alpha cell. Glutamate then acts on iGluRs of the AMPA/kainate type, resulting in membrane depolarization, opening of voltage-gated Ca(2+) channels, increase in cytoplasmic free Ca(2+) concentration, and enhanced glucagon release. In vivo blockade of iGluRs reduces glucagon secretion and exacerbates insulin-induced hypoglycemia in mice. Hence, the glutamate autocrine feedback loop endows the alpha cell with the ability to effectively potentiate its own secretory activity. This is a prerequisite to guarantee adequate glucagon release despite relatively modest changes in blood glucose concentration under physiological conditions.
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Affiliation(s)
- Over Cabrera
- Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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Abstract
Catecholamines (noradrenaline and adrenaline) are catabolic hormones secreted during stress. They initiate many metabolic processes including increased production of both ketoacids and lactic acid. Support for a direct participation of these hormones in the development and/or maintenance of ketoacidosis includes: (1) the high incidence of stress (approx. 70%) as a precipitating factor for ketoacidosis; (2) the elevated plasma levels of noradrenaline (norepinephrine) in patients with ketoacidosis; (3) the rise in plasma concentrations of ketone bodies during catecholamine infusion; and (4) the reduction in the incidence of ketoacidosis with beta-adrenergic pharmacological blockade. Support for a direct participation of catecholamines in the development and/or maintenance of lactic acidosis includes: (1) the common association of stress and lactic acidosis; (2) the rise in plasma lactate concentration during adrenaline (epinephrine) infusion; (3) the precipitation of lactic acidosis by adrenaline intoxication and phaeochromocytoma; and (4) the vasoconstrictor effects of catecholamines leading to tissue anoxia and lactic acid production. Thus, in susceptible patients, catecholamines may be principal determinants of whether ketoacidosis and/or lactic acidosis develops.
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85
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Leonard JV. Problems in the congenital lactic acidoses. CIBA FOUNDATION SYMPOSIUM 2008; 87:340-56. [PMID: 6280937 DOI: 10.1002/9780470720691.ch19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The congenital lactic acidosis form a heterogeneous group of inborn errors that includes defects of gluconeogenesis, the pyruvate dehydrogenase complex, the Krebs cycle and the respiratory chain. These disorders are not easily classified because of the absence of specific metabolites, difficulties in providing suitable tissue specimens and technical problems with the enzyme assays. The commonest causes of lactic acidosis due to inborn errors are the deficiencies of glucose-6-phosphatase and fructose bisphosphatase, which present with hypoglycaemia, lactic acidosis and hepatomegaly. Pyruvate carboxylase and phosphoenolpyruvate deficiencies vary considerably in both clinical expression and biochemical findings. Neurological symptoms predominate in defects of the pyruvate dehydrogenase complex, and some cases of the spinocerebellar ataxias may be due to partial defects of the pyruvate and 2-oxoglutarate dehydrogenase complexes.
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86
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Miles JM, Haymond MW, Gerich JE. Effects of free fatty acids, insulin, glucagon and adrenaline on ketone body production in humans. CIBA FOUNDATION SYMPOSIUM 2008; 87:192-213. [PMID: 7042239 DOI: 10.1002/9780470720691.ch11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In normal human subjects, when plasma insulin, glucagon and growth hormone were 'clamped' at basal concentrations (by infusion of somatostatin plus replacement infusion of these hormones), infusion of Intralipid and heparin increased plasma free fatty acid (FFA) concentrations to approx. 1.3 mM, and ketone body production increased 4-5 fold to approx. 11 mumol . kg -1 . min-1. Hyperglucagonaemia did not further increase ketogenesis. In conditions of combined insulin and glucagon deficiency (by infusion of somatostatin without insulin and glucagon), administration of Intralipid and heparin increased plasma FFA concentrations to approx. 2.2 mM but a further increase in ketone body production did not accompany this increase. In these conditions hyperglucagonaemia increased ketogenesis by 2-3 fold the increment seen in control studies. Infusion of adrenaline (epinephrine) in conditions in which insulin secretion was not inhibited caused only a transient increase in plasma FFA concentrations and in ketone body production. These data indicate: (1) that in humans increased FFA availability can markedly augment ketogenesis in the absence of insulin deficiency and without hyperglucagonaemia; (2) that glucagon can increase ketone body production during insulin deficiency but not in its absence; and (3) that insulin deficiency may be accompanied by increased ketogenesis only because of a lack of its restraint on lipolysis and because of the action of glucagon. Glucagon may be important in determining the magnitude of ketone body production for a given degree of FFA availability and insulin deficiency, and may be necessary for attainment of maximal rates of ketogenesis. Adrenaline increases ketone body production in humans, but whether this is primarily due to a direct effect on the liver or is mediated through enhancement of lipolysis remains to be determined.
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87
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Parker DR, Braatvedt GD, Bargiota A, Newrick PG, Brown S, Gamble G, Corrall RJM. Glucagon is absorbed from the rectum but does not hasten recovery from hypoglycaemia in patients with type 1 diabetes. Br J Clin Pharmacol 2008; 66:43-9. [PMID: 18507661 DOI: 10.1111/j.1365-2125.2008.03173.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
AIMS A failure to secrete glucagon during hypoglycaemia is near universal in patients with type 1 diabetes 5 years after disease onset and may contribute to delayed counter-regulation during hypoglycaemia. Rectal glucagon delivery may assist glucose recovery following insulin-induced hypoglycaemia in such patients and has not been previously studied. METHODS Six male patients (age 21-38 years) with type 1 diabetes (median duration 10 years) without microvascular complications, were studied supine after an overnight fast on two separate occasions at least 14 days apart. After omission of their usual morning insulin and 45 min rest, hypoglycaemia was induced by an intravenous insulin infusion which was terminated when capillary glucose concentration reached 2.5 mmol l(-1). Subjects were randomized to insert a rectal suppository containing 100 mg indomethacin alone (placebo) or 100 mg indomethacin plus 1 mg glucagon at the hypoglycaemic reaction. Serial measurements were made for 120 min. RESULTS In the two groups, mean (SD) plasma glucose concentrations fell to a similar nadir of 1.8 (0.7) mmol l(-1) (placebo) and 2.1 (1.2) mmol l(-1) (glucagon). Peak plasma glucagon following hypoglycaemia was higher in the glucagon group; 176 (32) ng l(-1)vs. 99 (22) ng l(-1) after placebo (P = 0.006). However, the glucose recovery rate over 120 min after hypoglycaemia did not differ significantly. CONCLUSIONS Our results provide evidence for the absorption of glucagon from the rectum. They also indicate that 1 mg does not constitute a useful mode of therapy to hasten recovery from hypoglycaemia in patients with type 1 diabetes.
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Affiliation(s)
- David R Parker
- Department of Medicine, University of Bristol, Bristol Royal Infirmary, Bristol, UK
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88
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Fagerholm V, Scheinin M, Haaparanta M. alpha2A-adrenoceptor antagonism increases insulin secretion and synergistically augments the insulinotropic effect of glibenclamide in mice. Br J Pharmacol 2008; 154:1287-96. [PMID: 18493247 DOI: 10.1038/bjp.2008.186] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE The imidazoline-type alpha2-adrenoceptor antagonists (+/-)-efaroxan and phentolamine increase insulin secretion and reduce blood glucose levels. It is not known whether they act by antagonizing pancreatic beta-cell alpha2-adrenoceptors or by alpha2-adrenoceptor-independent mechanisms. Many imidazolines inhibit the pancreatic beta-cell KATP channel, which is the molecular target of sulphonylurea drugs used in the treatment of type II diabetes. To investigate the mechanisms of action of (+/-)-efaroxan and phentolamine, alpha2A-adrenoceptor knockout (alpha2A-KO) mice were used. EXPERIMENTAL APPROACH Effects of (+/-)-efaroxan, 5 mg kg(-1), and phentolamine, 1 mg kg(-1), on blood glucose and insulin levels were compared with those of the non-imidazoline alpha2-adrenoceptor antagonist [8aR,12aS,13aS]-5,8,8a,9,10,11,12,12a,13,13a-decahydro-3-methoxy-12-(ethylsulphonyl)-6H-isoquino[2,1-g][1,6]naphthyridine (RS79948-197), 1 mg kg(-1), and the sulphonylurea glibenclamide, in alpha2A-KO and control (wild type (WT)) mice. KEY RESULTS In fed WT mice, (+/-)-efaroxan, phentolamine and RS79948-197 reduced blood glucose and increased insulin levels. Fasting abolished these effects. In fed alpha2A-KO mice, (+/-)-efaroxan, phentolamine and RS79948-197 did not alter blood glucose or insulin levels, and in fasted alpha2A-KO mice, blood glucose levels were increased. Glibenclamide, at a dose only moderately efficacious in WT mice (5 mg kg(-1)), caused severe hyperinsulinaemia and hypoglycaemia in alpha2A-KO mice. This was mimicked in WT mice by co-administration of RS79948-197 with glibenclamide. CONCLUSIONS AND IMPLICATIONS These results suggest that (+/-)-efaroxan and phentolamine increase insulin secretion by inhibition of beta-cell alpha2A-adrenoceptors, and demonstrate a critical role for alpha2A-adrenoceptors in limiting sulphonylurea-induced hyperinsulinaemia and hypoglycaemia.
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Affiliation(s)
- V Fagerholm
- Turku PET Centre/Preclinical Imaging, Turku, Finland.
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89
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Abstract
To assess the changes in counterregulatory hormones overnight after an afternoon of structured exercise or sedentary activity in children with type 1 diabetes mellitus (T1DM), the Diabetes Research in Children Network (DirecNet) studied 50 children (10 to <18 yr) with T1DM in five clinical research centers on two separate days (with and without an afternoon exercise session) using a crossover design. Glucose, epinephrine, norepinephrine, cortisol, growth hormone (GH), and glucagon concentrations were measured hourly overnight. Nocturnal hypoglycemia [plasma glucose concentrations < or =70 mg/dL (3.9 mmol/L)] occurred more frequently on the nights following exercise (56 vs. 36%; p = 0.008). Mean hourly concentrations of most hormones did not differ between sedentary or exercise nights or between nights with or without hypoglycemia. Spontaneous nocturnal hypoglycemia only stimulated small increases in plasma epinephrine and GH concentrations and failed to cause a rise in norepinephrine, cortisol, or glucagon levels in comparison with values during the hour before or after hypoglycemia or other times during those same nights. Counterregulatory hormone responses to spontaneous nocturnal hypoglycemia were markedly decreased regardless of whether there was antecedent afternoon exercise in children with T1DM. Sleep-induced impairments in counterregulatory hormone responses likely contribute to the increased risk of hypoglycemia during the entire overnight period in youth with T1DM.
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90
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Abstract
The glucoincretins, glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP), are intestinal peptides secreted in response to glucose or lipid intake. Data on isolated intestinal tissues, dietary treatments and knockout mice strongly suggest that GIP and GLP-1 secretion requires glucose and lipid metabolism by intestinal cells. However, incretin secretion can also be induced by non-digestible carbohydrates and involves the autonomic nervous system and endocrine factors such as GIP itself and cholecystokinin. The classical pharmacological approach and the recent use of knockout mice for the incretin receptors have shown that a remarkable feature of incretins is the ability to stimulate insulin secretion in the presence of hyperglycaemia only, hence avoiding any hypoglycaemic episode. This important role is the basis of ongoing clinical trials using GLP-1 analogues. Since most of the data concern GLP-1, we will focus on this incretin. In addition, GLP-1 is involved in glucose sensing by the autonomic nervous system of the hepato-portal vein controlling muscle glucose utilization and indirectly insulin secretion. GLP-1 has been shown to decrease glucagon secretion, food intake and gastric emptying, preventing excessive hyperglycaemia and overfeeding. Another remarkable feature of GLP-1 is its secretion by the brain. Recently, elegant data showed that cerebral GLP-1 is involved in cognition and memory. Experiments using knockout mice suggest that the lack of the GIP receptor prevents diet-induced obesity. Consequently, macronutrients controlling intestinal glucose and lipid metabolism would control incretin secretion and would consequently be beneficial for health. The control of incretin secretion represents a major goal for new therapeutic as well as nutrition strategies for treating and/or reducing the risk of hyperglycaemic syndromes, excessive body weight and thus improvement of well-being.
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Affiliation(s)
- Rémy Burcelin
- UMR 5018 CNRS-UPS and IFR 31, Rangueil Hospital, Toulouse, France.
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91
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Rickels MR, Schutta MH, Mueller R, Kapoor S, Markmann JF, Naji A, Teff KL. Glycemic thresholds for activation of counterregulatory hormone and symptom responses in islet transplant recipients. J Clin Endocrinol Metab 2007; 92:873-9. [PMID: 17192287 DOI: 10.1210/jc.2006-2426] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
CONTEXT In patients with type 1 diabetes and reduced awareness of hypoglycemia, the glycemic thresholds for activation of counterregulatory hormone and symptom responses to hypoglycemia are impaired, in part due to recurrent episodes of hypoglycemia. Islet transplantation can ameliorate occurrences of hypoglycemia in these patients. OBJECTIVE The objective of the study was to determine whether the avoidance of hypoglycemia achieved through islet transplantation results in improved glycemic thresholds for counterregulatory responses. SETTING The study was conducted at a general clinical research center. PARTICIPANTS Seven islet transplant recipients, six type 1 diabetic, and eight nondiabetic control subjects participated in the study. INTERVENTION We performed a stepped hyperinsulinemic hypoglycemic clamp and, in 12 subjects, a paired hyperinsulinemic euglycemic clamp to calculate the glycemic thresholds for and magnitude of counterregulatory responses. RESULTS The glycemic thresholds for all counterregulatory hormone and symptom responses in the islet transplant group were comparable with normal and higher than in the type 1 diabetes group (P < 0.01 for glucagon; P < 0.05 for epinephrine). The magnitude of the glucagon and epinephrine responses in the islet transplant group, although greater than in the type 1 diabetes group (P < 0.05 for both), remained less than normal (P < 0.01 for glucagon; P < 0.05 for epinephrine). The magnitude of GH secretion in the islet transplant group was comparable with normal and greater than in the type 1 diabetes group (P < 0.05). CONCLUSIONS The glycemic thresholds for activation of counterregulatory hormone and symptom responses appear normal after islet transplantation; however, the magnitudes of the glucagon and epinephrine responses remain impaired.
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Affiliation(s)
- Michael R Rickels
- University of Pennsylvania School of Medicine, Division of Endocrinology, Diabetes, and Metabolism, 778 Clinical Research Building, 415 Curie Boulevard, Philadelphia, Pennsylvania 19104-6149, USA.
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92
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Luquet S, Phillips CT, Palmiter RD. NPY/AgRP neurons are not essential for feeding responses to glucoprivation. Peptides 2007; 28:214-25. [PMID: 17194499 DOI: 10.1016/j.peptides.2006.08.036] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Accepted: 08/03/2006] [Indexed: 10/23/2022]
Abstract
Animals respond to hypoglycemia by eating and by stimulating gluconeogenesis. These responses to glucose deprivation are initiated by glucose-sensing neurons in the brain, but the neural circuits that control feeding behavior are not well established. Neurons in the arcuate region of the hypothalamus that express neuropeptide Y (NPY) and agouti-related protein (AgRP) have been implicated in mediating the feeding response to glucoprivation. We devised a method to selectively ablate these neurons in neonatal mice and then tested adult mice for their feeding responses to fasting, mild hypoglycemia, 2-deoxy-d-glucose and a ghrelin receptor agonist. Whereas the feeding response to the ghrelin receptor agonist was completely abrogated, the feeding response to glucoprivation was normal. The feeding response after a fast was attenuated when standard chow was available but normal with more palatable solid or liquid diet. We conclude that NPY/AgRP neurons are not necessary for generating or mediating the orexigenic response to glucose deficiency, but they are essential for the feeding response to ghrelin and refeeding on standard chow after a fast.
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Affiliation(s)
- Serge Luquet
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Box 357370, Seattle, WA 98195, United States
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93
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Gromada J, Franklin I, Wollheim CB. Alpha-cells of the endocrine pancreas: 35 years of research but the enigma remains. Endocr Rev 2007; 28:84-116. [PMID: 17261637 DOI: 10.1210/er.2006-0007] [Citation(s) in RCA: 424] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glucagon, a hormone secreted from the alpha-cells of the endocrine pancreas, is critical for blood glucose homeostasis. It is the major counterpart to insulin and is released during hypoglycemia to induce hepatic glucose output. The control of glucagon secretion is multifactorial and involves direct effects of nutrients on alpha-cell stimulus-secretion coupling as well as paracrine regulation by insulin and zinc and other factors secreted from neighboring beta- and delta-cells within the islet of Langerhans. Glucagon secretion is also regulated by circulating hormones and the autonomic nervous system. In this review, we describe the components of the alpha-cell stimulus secretion coupling and how nutrient metabolism in the alpha-cell leads to changes in glucagon secretion. The islet cell composition and organization are described in different species and serve as a basis for understanding how the numerous paracrine, hormonal, and nervous signals fine-tune glucagon secretion under different physiological conditions. We also highlight the pathophysiology of the alpha-cell and how hyperglucagonemia represents an important component of the metabolic abnormalities associated with diabetes mellitus. Therapeutic inhibition of glucagon action in patients with type 2 diabetes remains an exciting prospect.
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Affiliation(s)
- Jesper Gromada
- Novartis Institutes for BioMedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA.
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94
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Fanelli CG, Porcellati F, Rossetti P, Bolli GB. Glucagon: the effects of its excess and deficiency on insulin action. Nutr Metab Cardiovasc Dis 2006; 16 Suppl 1:S28-S34. [PMID: 16530126 DOI: 10.1016/j.numecd.2005.10.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 10/20/2005] [Accepted: 10/20/2005] [Indexed: 10/25/2022]
Abstract
AIM To review the role that glucagon plays in physiology, physiopathology and clinical medicine. DATA SYNTHESIS Glucagon assays employing specific radioimmunoassay (RIA) techniques are now widely used to characterize pathologic conditions where the effect of the excess or deficiency of glucagon on insulin actions might play a role. Glucagon excess counteracts the action of insulin on glucose metabolism by stimulating glycogenolysis and gluconeogenesis. Aside from glucagon excess in association with glucagonoma, glucagon excess is found in several metabolic disturbances. In diabetes mellitus, hyperglycaemia is the consequence of the glycogenolytic and gluconeogenic effects of glucagon excess occurring in the setting of a relative insulin deficiency (i.e. Type 2 diabetes), whereas excess of glucagon and absent insulin levels are typical features of diabetic ketoacidosis. Although plasma glucagon levels of patients with diabetes are usually increased relative to the prevailing plasma glucose concentrations, it is a paradox that in those patients glucagon levels fail to rise when hypoglycaemia develops. Since glucagon release is considered the primary defence against insulin-induced hypoglycaemia, the defective response of glucagon to hypoglycaemia may favour the development of severe hypoglycaemia. Such defective response to hypoglycaemia in diabetes can be regarded as a condition of selective glucagon deficiency the mechanisms of which remain to be elucidated. CONCLUSION The most common condition associated with glucagon excess or deficiency is diabetes mellitus. Glucagon excess contributes to hyperglycaemia whereas reduced glucagon response to insulin-induced hypoglycaemia promotes severe hypoglycaemia. It is expected that drugs that are able to reduce glucagon secretion in concert with strategies directed to recover glucagon secretion to hypoglycaemia might contribute to improve the overall glycaemic control in diabetes.
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Affiliation(s)
- C G Fanelli
- Department of Internal Medicine, Section of Endocrinology and Metabolism, University of Perugia, Via E. Dal Pozzo, I-06126 Perugia, Italy
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95
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Bingham EM, Dunn JT, Smith D, Sutcliffe-Goulden J, Reed LJ, Marsden PK, Amiel SA. Differential changes in brain glucose metabolism during hypoglycaemia accompany loss of hypoglycaemia awareness in men with type 1 diabetes mellitus. An [11C]-3-O-methyl-D-glucose PET study. Diabetologia 2005; 48:2080-9. [PMID: 16143864 DOI: 10.1007/s00125-005-1900-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Accepted: 05/11/2005] [Indexed: 12/30/2022]
Abstract
AIMS/HYPOTHESIS Hypoglycaemia unawareness in type 1 diabetes increases the risk of severe hypoglycaemia and impairs quality of life for people with diabetes. To explore the central mechanisms of hypoglycaemia awareness, we used [11C]-3-O-methyl-D-glucose (CMG) positron emission tomography (PET) to measure changes in global and regional brain glucose metabolism between euglycaemia and hypoglycaemia in aware and unaware diabetic subjects. MATERIALS AND METHODS Twelve men with type 1 diabetes, of whom six were characterised as aware and six as unaware of hypoglycaemia, underwent two CMG-PET brain scans while plasma glucose was controlled by insulin and glucose infusion either at euglycaemia (5 mmol/l) or at hypoglycaemia (2.6 mmol/l) in random order. RESULTS With hypoglycaemia, symptoms and sweating occurred only in the aware group. Brain glucose content fell in both groups (p=0.0002; aware, 1.18+/-0.45 to 0.02+/-0.2 mmol/l; unaware, 1.07+/-0.46 to 0.19+/-0.23 mmol/l), with a relative increase in tracer uptake in prefrontal cortical regions, including the anterior cingulate. No detectable differences were found between groups in global brain glucose transport parameters (K1, k2). The cerebral metabolic rate for glucose (CMRglc) showed a relative rise in the aware subjects (11.839+/-2.432 to 13.958+/-2.372) and a fall in the unaware subjects (from 12.457+/-1.938 to 10.16+/-0.801 micromol 100 g(-1) min(-1), p=0.043). CONCLUSIONS/INTERPRETATION Hypoglycaemia is associated with reduced brain glucose content in aware and unaware subjects, with a relative preservation of metabolism in areas associated with sympathetic activation. The relative rise in global glucose metabolic rate seen in aware subjects during hypoglycaemia contrasted with the relative fall in the unaware subjects and suggests that cortical neuronal activation is a necessary correlate of the state of hypoglycaemia awareness.
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Affiliation(s)
- E M Bingham
- Department of Diabetes, Endocrinology and Internal Medicine, Guy's, King's and St Thomas' School of Medicine, King's College, London, UK
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96
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van der Horst ICC, Zijlstra F. Potential beneficial mechanisms of insulin (glucose-potassium) in acute myocardial infarction. Neth Heart J 2005; 13:233-238. [PMID: 25696497 PMCID: PMC2497354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
In the time-span of almost a century, a large amount of experimental evidence has been accumulated that underlines the importance of glucose metabolism during ischaemia/reperfusion of the heart. As early as 1912, Goulston suggested that treatment with glucose could be beneficial in several heart diseases. The first experimental results on the mechanical effects of insulin and glucose in the isolated heart were reported by Visscher and Muller in 1926. In 1935, Evans and colleagues showed that the uptake of glucose is increased in the ischaemic myocardium. Almost 30 years later, Sodi-Pallares and colleagues suggested that metabolic interference during myocardial ischaemia with GIK infusion decreased electrocardiographic signs of ischaemia. They also showed that glucose-insulin-potassium (GIK) infusion resulted in a lower occurrence of arrhythmias. They attributed this effect mainly to the influx of potassium in ischaemic cardiomyocytes. In order to further stimulate potassium transport into the cell, insulin was administered. Consequently, the rise of intercellular calcium is curtailed by the influx of potassium and so the incidence of arrhythmias is reduced. However, systemic infusion of insulin stimulates the uptake of glucose in many celltypes, which may result in hypoglycaemic episodes. Consequently, it is not possible to administer potassium and insulin in high concentrations without adding glucose. Interventions in the glucose metabolism in the clinical arena, whether or not used to correct acute hyperglycaemia, encompass three potentially effective elements: glucose, insulin and potassium.
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97
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Gosmanov NR, Szoke E, Israelian Z, Smith T, Cryer PE, Gerich JE, Meyer C. Role of the decrement in intraislet insulin for the glucagon response to hypoglycemia in humans. Diabetes Care 2005; 28:1124-31. [PMID: 15855577 DOI: 10.2337/diacare.28.5.1124] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Animal and in vitro studies indicate that a decrease in beta-cell insulin secretion, and thus a decrease in tonic alpha-cell inhibition by intraislet insulin, may be an important factor for the increase in glucagon secretion during hypoglycemia. However, in humans this role of decreased intraislet insulin is still unclear. RESEARCH DESIGN AND METHODS We studied glucagon responses to hypoglycemia in 14 nondiabetic subjects on two separate occasions. On both occasions, insulin was infused from 0 to 120 min to induce hypoglycemia. On one occasion, somatostatin was infused from -60 to 60 min to suppress insulin secretion, so that the decrement in intraislet insulin during the final 60 min of hypoglycemia would be reduced. On the other occasion, subjects received an infusion of normal saline instead of the somatostatin. RESULTS During the 2nd h of the insulin infusion, when somatostatin or saline was no longer being infused, plasma glucose ( approximately 2.6 mmol/l) and insulin levels ( approximately 570 pmol/l) were comparable in both sets of experiments (both P > 0.4). In the saline experiments, insulin secretion remained unchanged from baseline (-90 to -60 min) before insulin infusion and decreased from 1.20 +/- 0.12 to 0.16 +/- 0.04 pmol . kg(-1) . min(-1) during insulin infusion (P < 0.001). However, in the somatostatin experiments, insulin secretion decreased from 1.18 +/- 0.12 pmol . kg(-1) . min(-1) at baseline to 0.25 +/- 0.09 pmol . kg(-1) . min(-1) before insulin infusion so that it did not decrease further during insulin infusion (-0.12 +/- 0.10 pmol . kg(-1) . min(-1), P = 0.26) indicating the complete lack of a decrement in intraislet insulin during hypoglycemia. This was associated with approximately 30% lower plasma glucagon concentrations (109 +/- 7 vs. 136 +/- 9 pg/ml, P < 0.006) and increments in plasma glucagon above baseline (41 +/- 8 vs. 67 +/- 11 pg/ml, P < 0.008) during the last 15 min of the hypoglycemic clamp. In contrast, increases in plasma growth hormone were approximately 70% greater during hypoglycemia after somatostatin infusion (P < 0.007), suggesting that to some extent the increases in plasma glucagon might have reflected a rebound in glucagon secretion. CONCLUSIONS These results provide direct support for the intraislet insulin hypothesis in humans. However, the exact extent to which a decrement in intraislet insulin accounts for the glucagon responses to hypoglycemia remains to be established.
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Affiliation(s)
- Niyaz R Gosmanov
- Carl T. Hayden VA Medical Center, 650 E. Indian School Road, Phoenix, AZ 85012, USA.
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98
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Sindelar DK, Ste Marie L, Miura GI, Palmiter RD, McMinn JE, Morton GJ, Schwartz MW. Neuropeptide Y is required for hyperphagic feeding in response to neuroglucopenia. Endocrinology 2004; 145:3363-8. [PMID: 15064281 DOI: 10.1210/en.2003-1727] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To investigate the role played by the orexigenic peptide, neuropeptide Y (NPY), in adaptive responses to insulin-induced hypoglycemia, we measured hypothalamic, feeding, and hormonal responses to this stimulus in both wild-type (Npy+/+) and NPY-deficient (Npy-/-) mice. After administration of insulin at a dose (60 mU ip) sufficient to cause moderate hypoglycemia (plasma glucose levels, 40 +/- 3 and 37 +/- 2 mg/dl for Npy+/+ and Npy-/- mice, respectively; P = not significant), 4-h food intake was increased 2.5-fold in Npy+/+ mice relative to saline-injected controls. By comparison, the increase of intake in Npy-/- mice was far smaller (45%) and did not achieve statistical significance (P = 0.08). Hyperphagic feeding in response to insulin-induced hypoglycemia was therefore markedly attenuated in mice lacking NPY, and a similar feeding deficit was detected in these animals after neuroglucopenia induced by 2-deoxyglucose (500 mg/kg ip). A role for NPY in glucoprivic feeding is further supported by our finding that Npy mRNA content (measured by real-time PCR) increased 2.4-fold in the hypothalamus of Npy+/+ mice by 7 h after insulin injection. Unlike the feeding deficits observed in mice lacking NPY, the effect of hypoglycemia to increase plasma glucagon and corticosterone levels was fully intact in these animals, as were both the nadir glucose value and time to recovery of euglycemia after insulin injection (P = not significant). We conclude that NPY signaling is required for hyperphagic feeding, but not neuroendocrine responses to moderate hypoglycemia.
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Affiliation(s)
- Dana K Sindelar
- Department of Medicine, Harborview Medical Centr, Howard Hughes Medical Institute, University of Washington, Seattle 98195, USA
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99
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Hope KM, Tran POT, Zhou H, Oseid E, Leroy E, Robertson RP. Regulation of alpha-cell function by the beta-cell in isolated human and rat islets deprived of glucose: the "switch-off" hypothesis. Diabetes 2004; 53:1488-95. [PMID: 15161753 DOI: 10.2337/diabetes.53.6.1488] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The "switch-off" hypothesis to explain beta-cell regulation of alpha-cell function during hypoglycemia has not been assessed previously in isolated islets, largely because they characteristically do not respond to glucose deprivation by secreting glucagon. We examined this hypothesis using normal human and Wistar rat islets, as well as islets from streptozotocin (STZ)-administered beta-cell-deficient Wistar rats. As expected, islets perifused with glucose and 3-isobutryl-1-methylxanthine did not respond to glucose deprivation by increasing glucagon secretion. However, if normal rat islets were first perifused with 16.7 mmol/l glucose to increase endogenous insulin secretion, followed by discontinuation of the glucose perifusate, a glucagon response to glucose deprivation was observed (peak change within 10 min after switch off = 61 +/- 15 pg/ml [mean +/- SE], n = 6, P < 0.01). A glucagon response from normal human islets using the same experimental design was also observed. A glucagon response (peak change within 7 min after switch off = 31 +/- 1 pg/ml, n = 3, P < 0.01) was observed from beta-cell-depleted, STZ-induced diabetic rats whose islets still secreted small amounts of insulin. However, when these islets were first perifused with both exogenous insulin and 16.7 mmol/l glucose, followed by switching off both the insulin and glucose perifusate, a significantly larger (P < 0.05) glucagon response was observed (peak change within 7 min after switch off = 71 +/- 11 pg/ml, n = 4, P < 0.01). This response was not observed if the insulin perifusion was not switched off when the islets were deprived of glucose or when insulin was switched off without glucose deprivation. These data uniquely demonstrate that both normal, isolated islets and islets from STZ-administered rats can respond to glucose deprivation by releasing glucagon if they are first provided with increased endogenous or exogenous insulin. These results fully support the beta-cell switch-off hypothesis as a key mechanism for the alpha-cell response to hypoglycemia.
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Affiliation(s)
- Kristine M Hope
- Pacific Northwest Research Institute, 720 Broadway, Seattle, WA 98122, USA
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Zhou H, Tran POT, Yang S, Zhang T, LeRoy E, Oseid E, Robertson RP. Regulation of alpha-cell function by the beta-cell during hypoglycemia in Wistar rats: the "switch-off" hypothesis. Diabetes 2004; 53:1482-7. [PMID: 15161752 DOI: 10.2337/diabetes.53.6.1482] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The glucagon response is the first line of defense against hypoglycemia and is lost in insulin-dependent diabetes. The beta-cell "switch-off" hypothesis proposes that a sudden cessation of insulin secretion from beta-cells into the portal circulation of the islet during hypoglycemia is a necessary signal for the glucagon response from downstream alpha-cells. Although indirect evidence exists to support this hypothesis, it has not been directly tested in vivo by provision and then discontinuation of regional reinsulinization of alpha-cells at the time of a hypoglycemic challenge. We studied streptozotocin (STZ)-induced diabetic Wistar rats that had no glucagon response to a hypoglycemic challenge. We reestablished insulin regulation of the alpha-cell by regionally infusing insulin (0.025 microU/min) directly into the superior pancreaticoduodenal artery (SPDa) of STZ-administered rats at an infusion rate that did not alter systemic venous glucose levels. SPDa insulin infusion was switched off simultaneously when blood glucose fell to <60 mg/dl after a jugular venous insulin injection. This maneuver restored the glucagon response to hypoglycemia (peak change within 5-10 min = 326 +/- 98 pg/ml, P < 0.05; and peak change within 15-20 min = 564 +/- 148 pg/ml, P < 0.01). No response was observed when the SPDa insulin infusion was not turned off (peak change within 5-10 min = 44 +/- 85 pg/ml, P = NS; and peak change within 15-20 min = 67 +/- 97 pg/ml, P = NS) or when saline instead of insulin was infused and then switched off (peak change within 5-10 min = -44 +/- 108 pg/ml, P = NS; and peak change within 15-20 min = -13 +/- 43 pg/ml, P = NS). No responses were observed during euglycemia (peak change within 5-10 min = 48 +/- 35 pg/ml, P = NS; and peak change within 15-20 min = 259 +/- 129 pg/ml, P = NS) or hyperglycemia (peak change within 5-10 min = 49 +/- 62 pg/ml, P = NS; and peak change within 15-20 min = 138 +/- 87 pg/ml, P = NS). Thus, the glucagon response to hypoglycemia that was absent in rats made diabetic by STZ was restored by regional infusion and then discontinuation of insulin. These data provide direct in vivo support for the beta-cell "switch-off" hypothesis and indicate that the alpha-cell is not intrinsically abnormal in insulin-dependent diabetes because of STZ-induced destruction of beta-cells.
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Affiliation(s)
- Huarong Zhou
- Pacific Northwest Research Institute, 720 Broadway, Seattle, WA 98122, USA
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