Electrical stimulation of the medial amygdala facilitates gastric acid secretion in conscious rats.

One hundred and twenty-seven conscious rats prepared with chronic gastric fistula were studied to investigate the effect of stimulation of the medial amygdala on gastric acid secretion. Gastric acid output was significantly increased by electrical stimulation of the medial amygdala in normal rats and the increase in acid secretion was completely abolished by vagotomy. Vagotomized rats, with or without amygdaloid stimulation, showed comparable levels of gastric acid output which were significantly lower than in controls. These results indicate that the amygdala effect on gastric acid secretion is carried via the vagus nerve. Subcutaneous injections of high doses of histamine increased gastric acid secretion which was further increased by amygdaloid stimulation. Plasma levels of gastrin were not significantly changed by stimulation of the medial amygdala with or without vagotomy. From the above results, we concluded that in conscious rats the medial amygdala plays a significant role in stimulating gastric acid secretion, the vagus nerve is involved in this process, but it is not mediated by release of either histamine or gastrin.