Serotoninergic control of somatostatin and gastrin release from the isolated rat stomach.

The influence of exogenous serotonin on the secretion of gastric somatostatin and gastrin was investigated under in vitro conditions using an isolated, vascularly perfused rat stomach preparation. Serotonin stimulated gastrin release, maximal effects were observed at 10(-6) M which increased gastrin levels by 78%; on the contrary, somatostatin secretion was inhibited (maximal inhibition of 56% at 10(-6) M). Changes in hormone secretion in response to serotonin were reversed by combined blockade of 5-HT1 and 5-HT2 receptors by methysergide and blockade of 5-HT2 receptors by ketanserin (10(-5) and 10(-6) M, respectively), and of cholinoreceptors by atropine (10(-5) M). It is concluded that in rats in vitro serotonin inhibits release of gastric somatostatin and stimulates gastrin secretion via specific serotonin receptors but muscarinic cholinergic receptors are also involved.