Serotonin as an inhibitor of gastrin.

A dose of exogenous serotonin (0.1 mg/kg/min) previously described to cause maximal acid inhibition, was infused into six chronically awake dogs and significantly inhibited acid output. Integrated basal gastrin output was inhibited from a mean of 232.6 pg-min/ml to 31.6 pg-min/ml (p < 0.05) by serotonin infusion. Antral explantation significantly increased gastrin levels from a mean control level of 163 +/- 71.1 pg/ml to a mean of 991.0 +/- 663.4 pg/ml (p < 0.05). These elevated gastrin levels were then not significantly inhibited by serotonin. The effect of serotonin on gastrin output has not previously been documented. Whereas acid inhibition was uniformly achieved, serotonin inhibited basal gastrin output (integrated gastrin output) but not a stimulated level of gastrin output. Serotonin may be an important 'enterogastrone', and its release may play a role both in acid inhibition and in preventing ulcer disease.