Distribution of Intraventricular Salmon Calcitonin and Suppression of Gastric Secretion

Abstract

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.

CNS Peptides and Regulation of Gastric Acid Secretion

“…Although [ 12 5 I]calcitonin appears rapidly in the peripheral circulation after intracerebroventricular injection into the rat, the highest amounts of intact calcitonin and breakdown products were retained by the brain, predominantly by the hypothalamus and the medulla, and to some extent by the kidneys, but not the stomach (90). In the dog, injection into the third ventricle was not associated with the appearance of immunoreactive calcitonin in the plasma (49).…”

Effect of Calcitonin on Gastric Emptying

“…Centrally or peripherally ad ministered calcitonin was shown to inhibit gastric acid secretion in rats [ 1,2] and in humans [3,4], Intracerebroventricular ad ministration of calcitonin was reported to alter the intestinal motor profile in rats [5][6][7], dogs [8] and sheep [9] by restoring the fasted motility pattern in fed animals. As closely related to the latter action should be considered the centrally mediated anorectic effect of calcitonin in rats [6,7] and sheep…”