Distribution of intraventricular salmon calcitonin and suppression of gastric secretion

Intracerebroventricularly (ICV) administered [125I] salmon calcitonin (sCT) was rapidly transported to the blood, but the permeability of the blood-brain barrier to sCT was low. ICV injected intact [125I]sCT was predominantly deposited in the periventricular mesencephalon and in the kidneys, and intravenously (IV) injected [125I]sCT in the kidneys, respectively. After both ICV and IV administration [125I]sCT was not retained by the stomach in large amounts. ICV and subcutaneously (SC) injected sCT caused suppression of gastric secretion volume, and of acid and pepsin outputs; the potency ratios between half maximal inhibitory amounts of sCT administered SC and ICV were 161, 252 and 13, respectively. On the other hand, perfusion of isolated whole mouse stomachs with sCT did not affect basal or stimulated acid and pepsin secretion. These findings indicate that sCT inhibits gastric acid secretion via receptors localized in the hypothalamus and in adjacent areas of the brain.