Buspirone inhibits corticotropin-releasing factor and stress-induced cecal motor response in rats by acung through 5-HT 1A receptors

Abstract

The effect of buspirone on corticotropin-rclcasing factor (CRF) and stress-stimulated cecal motility and its antagonism by 5-HT 1A (spiroxatrine) and σ (BMY 14802) antagonists were evaluated by electromyography in rats equipped with chronically implanted electrodes on the cecum and a small catheter into the right lateral ventricle of the brain. Exposure to mental stress. consisting of a fear-conditioned response, increased during 30 min the frequency of cecal spike bursts significantly (P < 0.01). The frequency of cecal spike bursts was also increased following intracerebroventricular injection of CRF (500 ng/kg). Buspirone (l mg/kg s.c.) abolished the stimulatory effects of mental stress and CRF on cecal motility. Whereas spiroxatrine (0.5 mg/kg s.c.) blocked the effect of buspirone on the colonie hypermotility induced by i.c.v. injection of CRF, BMY 14802 at a similar dose (0.5 mg/kg s.c.) was unable to block the action of buspirone. It is concluded that s.c. administration of buspirone suppresses the stress-induced cecal motor response through 5-HT 1A receptors, probably by inhibiting the central or peripheral pathways involved in CRF mediation of these effects.