Serotonin inhibition of in vitro insulin release from golden hamster pancreas

To assess the possible functional role of serotonin on insulin secretion, pieces of golden hamster pancreas were incubated in a modified Krebs-Ringer bicarbonate buffer. In 10^-4M concentration, serotonin suppressed basal insulin secretion and also insulin secretion that was stimulated by high glucose, tolbutamide, or dibutyryl cyclic AMP. Inhibition of insulin secretion by serotonin occurred over the entire range examined (1.0 × 10^-4 to 5.8 × 10^-4M). In a similar in vitro system, concentrations of serotonin as high as 5.8 × 10^-4M were without significant effects on basal or high glucose (3 mg/ml) stimulated insulin release from mouse pancreas. Thus, serotonin effect on the pancreatic β cell has some species difference. Serotonin may have a role as a physiological inhibitor of insulin secretion in some species.