Centrally applied histamine increases gastric acid secretion in rats.

Administration of 10-100 micrograms of histamine into the lateral cerebral ventricle of anaesthetized rats stimulated gastric acid secretion in a dose-dependent manner, while subcutaneous (s.c.) injections of the same doses produced clearly less pronounced increases in the acid output. In vagotomized rats only a marginal response to histamine given into the lateral ventricle was observed. When injected into the third cerebral ventricle the doses of histamine needed for the stimulation of gastric acid secretion were 1-10 micrograms, the effect being totally abolished by vagotomy. The results indicate that histamine is capable of stimulating gastric acid secretion by a central, vagal-dependent mechanism.