The action of serotonin on basal gastric secretion in the conscious rat after intraventricular and intraperitoneal administration.

In unanesthetized rats with chronic gastric fistulas the effect of various doses of 5-HT and atropine given intraperitoneally (i.p.) or into the lateral cerebral ventricle (i.c.) on basal gastric secretion was investigated. 5-HT given i.e. reduced HCl secretion more strongly than by the i.p. route. Atropine reduced gastric secretion equally after i.p. or i.e. administration. 5-HT given i.p. or i.c. produced a weaker inhibitory effect on basal gastric acid secretion than atropine. The stronger antisecretory action of 5-HT after i.c. than after i.p. administration indicates that the amine directly depresses the vegetative brain centers responsible for the basal secretory activity of the gastric mucosa.