Acid secretagogue action of structurally gamma-aminobutyric acid (GABA)-related compounds in rats.

The properties of GABA related compounds on gastric function were studied in standardized perfused rat stomach preparations. Intravenous GABA (400 mg/kg) produced a rapid increase in acid secretion. Acid secretagogue actions of 3-aminobutyric acid and 2-aminobutyric acid were less potent than that of GABA. Intravenous injection of 5-amino-n-valeric acid (400 mg/kg) stimulated gastric acid secretion, but 6-amino-n-caproic acid was inactive. Isoguvacine (40 mg/kg, s.c.) stimulated acid output, whereas guvacine, an isomer of isoguvacine, did not. Systemically administered 3-hydroxy-GABA and beta-(p-chlorophenyl)-GABA (PCPGABA) showed significant secretagogue actions. Acid responses to GABA-related compounds were significantly reduced by surgical truncal vagotomy and completely antagonized by atropine. The acid responses to PCPGABA and isoguvacine were partially augmented by yohimbine and propranolol. These results suggest that the secretagogue action of GABA is mimicked by structurally GABA-related compounds, which is mediated through cholinergic receptors, with slight implication of alpha-2 and beta-adrenoceptor mechanisms.