The mechanism of the inhibitory effects of Oren-gedoku-to (OGT) on gastric acid secretion in rats

Abstract

The effect of Oren-gedoku-to (OGT) on gastric acid secretion was examined in the perfused stomach of anesthetized rats. OGT (10-100 mg/kg) given intraperitoneally dose-dependently inhibited the gastric acid secretion stimulated by intracerebroventricular DN-1417, an analogue of TRH, but failed to inhibit the acid secretion stimulated by intracerebroventricular baclofen, an analogue of GABA. The inhibitory effect of OGT on DN-1417-induced acid secretion was antagonized by haloperidol (0.3 and 1.0 mg/kg, i.p.), a dopamine-1/2 antagonist or sulpiride (100 mg/kg, i.p.), a dopamine-2 antagonist; and it was also reversed by yohimbine (0.3 mg/kg, i.p.), an alpha-2 adrenergic antagonist, and phentolamine (1 mg/kg, i.p.), but not reversed by propranolol, a beta-antagonist and prazosin, an alpha-1 antagonist. These results suggest that the ability of OGT to reduce acid secretion is mediated via not only dopamine receptors but also alpha-2 adrenoceptors.