GABA-A RECEPTOR MEDIATED NEUROGENIC INHIBITION OF MOTILITY IN THE SMALL-INTESTINE OF URETHANE-ANESTHETIZED RATS

Intravenous GABA (0.1-3 mg/kg) induced transient relaxation of the duodenum in urethane anaesthetized rats. The effect of GABA was mimicked by homotaurine and antagonized by bicuculline, suggesting the involvement of GABA A receptors in this type of response. Duodenal relaxation induced by GABA was unaffected by i.v. hexamethonium, phentolamine propranolol or 6-hydroxydopamine but was prevented in preparations pretreated with topical tetrodotoxin thus indicating its neurogenic origin. The ability of GABA to induce neurogenic relaxation decreased rapidly when increasing the distance from the duodenum while relaxations by DMPP or noradrenaline were observed throughout the whole rat small intestine.