Serotonin release by hydrochloric acid: possibility of a feed-back mechanism

¹ Department of Medicine, Harvard Medical School, and the Medical Clinic, Peter Bent Brigham Hospital, Boston, Massachusetts

This investigation was carried out to determine whether the release of upper intestinal serotonin produced by hydrochloric acid perfusion was responsible for a subsequent inhibition of gastric secretion. To explore this possibility, gastric secretion in the pyloric-ligated rat was studied after the administration of varying quantities of serotonin through the rat portal vein. In another series of tests, the capacity of intestinally perfused hydrochloric acid to inhibit gastric secretion was studied in animals partially depleted of serotonin by reserpine or subjected to drug-induced chemical blockade of serotonin effect. Results indicate that serotonin infused through the portal vein does not alter gastric pH or secretory volume and that partial depletion of tissue serotonin or the use of serotonin antagonists does not prevent the intestinal suppression of gastric secretory function. It is therefore concluded that the intestinal release of serotonin is not a factor in the reduction of gastric acidity after HCl perfusion of the small intestine.