Effect of intracerebroventricular and intrahypothalamic administrations of picrotoxin on basal and stimulated gastric acid secretion.

The effects of intracerebroventricular and intrahypothalamic injections of picrotoxin, a GABA antagonist, on gastric acid secretion were studied in perfused stomachs of rats under anesthesia. Injection of picrotoxin into the lateral cerebroventricle inhibited the 2-deoxy-D-glucose-stimulated acid secretion. In experiments of intrahypothalamic injections, picrotoxin produced a significant depression of 2-deoxy-D-glucose-stimulated acid secretion when administered to the ventromedial hypothalamus but not to the lateral hypothalamus. In contrast, picrotoxin produced a definite stimulatory effect on basal acid secretion when injected to the lateral hypothalamus or ventromedial hypothalamus; the stimulatory effect of the injection to the lateral hypothalamus was greater than that of the injection to the ventromedial hypothalamus. These findings indicate that picrotoxin acts centrally, probably hypothalamus, to depress the 2-deoxy-D-glucose-stimulated acid secretion. On the other hand, blockade of GABA activity in the lateral hypothalamus or ventromedial hypothalamus may elicit gastric acid secretion. These results, indicate that central GABAergic mechanism is important in regulating gastric acid secretion in the rat.