Nociceptin prevents stress-induced ethanol- but not cocaine-seeking behavior in rats

This study examined whether nociceptin/orphanin FQ (NC), the endogenous lig and of the opioid receptor-like1 (ORL1) receptor, can block drug-seeking be havior induced by footshock stress. Male Wistar rats were trained to operan tly self-administer ethanol or cocaine, and then subjected to daily extinct ion training until responding ceased. Subsequent exposure to 15 min of inte rmittent footshock elicited robust reinstatement of responding at the previ ously drug-paired lever. NC (0.1-2.0 mu g; i.c.v.) significantly inhibited the effects of footshock stress on ethanol- but not cocaine-seeking behavio r. The results support the hypothesis that the NC system participates in th e regulation of behavioral responses to stress, and that drugs interacting with NC receptors may have therapeutic potential for the treatment of stres s-induced alcohol-seeking behavior and relapse. NeuroReport 11:1939-1943 (C ) 2000 Lippincott Williams & Wilkins.