Secretion of gastric acid inhibited by oxytocin injected into the hypothalamic paraventricular nucleus in the rat.

Gastric acid output was examined following oxytocin injection into the hypothalamic paraventricular nucleus (PVN) or into the vagus nucleus (X) of the medulla in rats with insulin-hypoglycemia. Gastric acid output was reduced following the injection of nanomolar quantities of oxytocin into these nuclei, and the response was dose-dependent. It was also noted that there was a synergistic action on the response by the peptide between PVN and X. The acid response was blocked by section of the vagus nerve at the subdiaphragmatic level or by prior administration of atropine sulfate. These observations suggest that oxytocin in the PVN is active in suppressing gastric acid secretion, and the vagal response is characteristic of activation of the PVN and X.