title: Insulin secretion in monosodium glutamate (MSG) obese rats submitted to aerobic exercise training.
abstract: The present study was designed to evaluate the effects of aerobic exercise training on glucose tolerance and insulin secretion of obese male Wistar rats (monosodium glutamate [MSG] administration, 4 mg/g-body weight, each other day, from birth to the 14th day). Fourteen weeks after the drug administration, the rats were separated into two groups: MSG-S (sedentary) and MSG-T (T = swimming, 1 h/day, 5 days/week, with an overload of 5% body weight for 10 weeks). Rats of the same age and strain injected with saline were used as control (C) and subdivided into two groups: C-S and C-T. Insulin and glucose responses during an oral glucose tolerance test (GTT) were evaluated by the estimation of the total areas under serum insulin (AI) and glucose (AG) curves. Glucose-induced insulin secretion by isolated pancreatic islets was also evaluated. MSG-S rats showed higher AI than C-rats while MSG-T rats presented lower AI than MSG-S rats. No differences in AG were observed among the 4 groups. Pancreatic islets from MSG-rats showed higher insulin secretion in response to low (2.8) and moderate (8.3 mM) concentrations of glucose than those from their control counterparts and no differences were observed between MSG-S and MSG-T rats. These results provide evidences that the hyperinsulinemia at low or moderate glucose concentrations observed in MSG-obese rats is, at least in part, a consequence of direct hypersecretion of the B cells and that chronic aerobic exercise is able to partially counteract the hyperinsulinemic state of these animals without disrupting glucose homeostasis.
authors.affiliation: Departamento de Educação Física, Instituto de Biociências, Universidade Estadual Paulista (UNESP), 13506-900 Rio Claro, SP, Brazil.
authors.forename: Claudio Teodoro
authors.initials: CT
authors.lastname: de Souza
authors.forename: Wilton Marlindo Santana
authors.initials: WM
authors.lastname: Nunes
authors.forename: Claudio Alexandre
authors.initials: CA
authors.lastname: Gobatto
authors.forename: Maria Alice Rostom
authors.initials: MA
authors.lastname: de Mello
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D005223:Fats / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000494:pharmacology; D005951:Glucose Tolerance Test; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009765:Obesity / Q000097:blood / Q000139:chemically induced / Q000378:metabolism* / Q000628:therapy*; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012970:Sodium Glutamate / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D001786:Blood Glucose; D005223:Fats; D007328:Insulin; D019344:Lactic Acid; D005947:Glucose; D012970:Sodium Glutamate