[Machanism of the stimulatory effect of intracerebroventricular administration of histamine on gastatric acid secretion induced by pentagastrin in rats].

The present experiment was designed to study the mechanism underlying the stimulatory effect of histamine (HA, i.c.v.) on the gastric acid secretion in subdiaphragmatic vagotomized SD rats. Gastric acid was continuously washed out with 37 degrees C saline by a perfusion pump. Drugs were injected into the third ventricle or the vein to examine the effect on gastric acid secretion and the level of plasma corticosterone. The results are as follows: (1) HA (1.0 microgram, i.c.v.) potentiated gastric acid secretion induced by G-5, which could be abolished by preintramuscular injection of diphenhydramine hydrochloride (8.0 micrograms). (2) Corticotropin-releasing factor (CRF) (0.5 microgram, 1.0 microgram, i.c.v.) augmented gastric acid secretion in a dose dependent manner. (3) HA (1.0 microgram, i.c.v.) increased the plasma corticosterone level. (4) Intravenous injection of corticosterone 21-sulfale (15, 30 micrograms) augmented gastric acid secretion in a dose dependent manner. These results suggested that intracerebroventricular injection of HA could stimulate the release of CRF by specificably binding with H1 receptor in some areas of hypothalamus, which, in turn, increased gastric acid secretion induced by G-5 via increasing the level of plasma corticosterone.