Enhanced analgesic effects of stress following chronic administration of naltrexone in rats.
Chronic administration of the long acting opiate antagonist naltrexone potentiated the analgesic effects of foot-shock stress in the hot-plate test in rats. No changes in pain responsiveness were noted in naltrexone-treated rats that were not subjected to the foot-shock treatment. The results suggest that chronic opiate receptor may lead to the development of supersensitivity in endogenous opiate systems that mediate the analgesic effects of stress.
D000698:Analgesia; D000818:Animals; D008297:Male; D009270:Naloxone / Q000031:analogs & derivatives*; D009271:Naltrexone / Q000494:pharmacology*; D051381:Rats; D011930:Reaction Time / Q000187:drug effects; D013312:Stress, Physiological / Q000503:physiopathology*; D013997:Time Factors
D009270:Naloxone; D009271:Naltrexone