In vivo studies on 5-hydroxytryptamine and insulin secretion in dogs and in man.

Abstract

5-Hydroxytryptamine (5-HT) effects on the insulin secretion of anaesthetized dogs and of humans were studied. From our investigations the following conclusions can be drawn: 5-HT when injected at a dose of 4.30 mg into the pancreatic artery, elicits a sharp rise of insulin concentration in pancreatico-duodenal vein; on the contrary, 21.50 mg of 5-HT is unable to modify insulin release. The infusion in fasting man of small amounts of 5-HT (∼ 0.50 μg/kg/min) during 1 h, does not alter blood glucose nor plasma insulin levels; a similar infusion, however, increases insulin response after oral glucose load. The results obtained in dogs are in agreement with the idea that 5-HT may modulate insulin release from the pancreas. The results in man suggest that enteramine released by the intestine may increase insulin secretion induced by the ingestion of glucose, through a fine interplay with other gut-factors.