The effect of fasting, diet, and actinomycin D on insulin secretion in the rat.
The present studies were performed to elucidate the mechanisms responsible for the impairment of glucose-stimulated insulin secretion observed in fasting. Rats fasted for 48 hr displayed marked impairment in their insulin secretory response to both oral and intravenous glucose. Glucose-stimulated insulin secretion was restored within 24 hr by refeeding; actinomycin D given before refeeding blocked the expected return of normal glucose-stimulated insulin secretion despite adequate food intake. Fasted rats refed a diet devoid of carbohydrate failed to display a return of normal insulin secretory responsiveness to oral glucose in contrast to rats fed isocalorically a high carbohydrate diet. Differences in insulin secretion in fed, fasted, and fasted-refed rats could not be attributed to changes in pancreatic insulin content. There was no significant difference in the insulin secretory response to aminophylline of fed, fasted, or fasted-refed rats. The intermittent pulsing of fasted rats with hyperglycemic episodes by the injection of small amounts of glucose (500 mg) intraperitoneally every 8 hr ameliorated the impairment of glucose-stimulated insulin secretion characteristic of the fasting state. These results suggest that the impairment of glucose-stimulated insulin secretion during fasting and its restoration by refeeding are regulated by changes in a glucose-inducible enzyme system in the pancreatic beta cell.
D000284:Administration, Oral; D000628:Aminophylline / Q000494:pharmacology; D000818:Animals; D003609:Dactinomycin / Q000494:pharmacology*; D004032:Diet; D005215:Fasting; D005947:Glucose / Q000008:administration & dosage; D006943:Hyperglycemia / Q000139:chemically induced; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D010179:Pancreas / Q000187:drug effects / Q000201:enzymology; D051381:Rats
D007328:Insulin; D003609:Dactinomycin; D000628:Aminophylline; D005947:Glucose