Opioid antagonists and drinking: evidence of kappa-receptor involvement.
Diprenorphine, naloxone, MR-2266-BS and WIN-44,441-3 were compared for their ability to antagonize morphine analgesia and to decrease deprivation-induced drinking in rats. Diprenorphine and naloxone were markedly more potent (32x) than MR-2266-BS and WIN-44,441-3 in antagonizing the analgesic effects of morphine. In contrast, diprenorphine, naloxone and MR-2266-BS decreased deprivation-induced drinking over a similar dose range. The doses required to reduce fluid consumption were higher than those necessary to antagonize morphine. WIN-44,441-3 was ineffective in decreasing drinking. The relatively similar potencies of diprenorphine, naloxone and MR-2266-BS for decreasing deprivation-induced drinking suggest that the effect on drinking involves antagonist activity at a kappa-opioid receptor.
D000818:Animals; D001392:Azocines; D001575:Benzomorphans / Q000031:analogs & derivatives / Q000494:pharmacology; D004326:Drinking / Q000187:drug effects*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology*; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects* / Q000502:physiology
D001392:Azocines; D001575:Benzomorphans; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D009270:Naloxone; C027247:MR 2266; C035969:quadazocine