Role of insulin in thermogenic responses to refeeding in 3-day-fasted rats.
Refeeding 3-day-fasted rats with 40 kJ carbohydrate (CHO; corn flour) or protein (gelatin) caused a rise in plasma insulin levels 3 h later, but refeeding fat or injection of norepinephrine (400 micrograms/kg) had no effect. Injection of insulin (0.25 U) caused a 15% rise in metabolic rate 24 h later in fasted rats that could be inhibited by treatment with propranolol. Refeeding rats with a single CHO meal produced an increase in oxygen consumption (15%) 24 h later that was inhibited by injection of diazoxide or 2-deoxy-D-glucose given at the time of the meal. The thermogenic response to insulin injection was unaffected by treatment with diazoxide or 2-deoxy-D-glucose. Genetically obese Zucker rats failed to increase metabolic rate after insulin or CHO. In normally fed lean rats, maintained on a stock diet or a palatable cafeteria diet, insulin (4 U) enhanced the thermogenic response to norepinephrine and stimulated resting metabolic rate (16%) in the cafeteria-fed rats. These data suggest that insulin is involved in the thermogenic responses to food and catecholamines.
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001833:Body Temperature Regulation / Q000187:drug effects; D003981:Diazoxide / Q000494:pharmacology; D004032:Diet; D004435:Eating; D005215:Fasting; D007328:Insulin / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010100:Oxygen / Q000097:blood; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011924:Rats, Zucker
D001786:Blood Glucose; D007328:Insulin; D011433:Propranolol; D003981:Diazoxide; D010100:Oxygen; D009638:Norepinephrine