EFFECT OF NOCICEPTIN ON HEART-RATE AND BLOOD-PRESSURE IN ANESTHETIZEDRATS

We now report on the effects of nociceptin, the endogenous ligand for the orphan opioid-like ORL1 receptor, on cardiovascular parameters (bl ood pressure and heart rate) in urethane-anaesthetized rats. Nocicepti n dose dependently (10-100 nmol/kg i.v.) produced a transient(< 10 min ) hypotension and bradycardia. The reduction in blood pressure was inh ibited by guanethidine pretreatment and unaffected by bilateral cervic al vagotomy. The bradycardia elicited by nociceptin was reduced after bilateral vagotomy and by guanethidine and was abolished by the combin ation of the two treatments. These findings indicate that nociceptin e xerts a pronounced depressant effect on cardiovascular function which is produced indirectly through a concomitant inhibition and activation , respectively, of the sympathetic and parasympathetic outflows to the cardiovascular system. (C) 1997 Elsevier Science B.V.