Naltrexone and the tail flick reflex.
Rats who received a tail flick test following repeated injections of 5 mg/kg of morphine were significantly more tolerant than rats who were not tested after each injection. Administration of 0.5 mg/kg of naltrexone hydrochloride, prior to the morphine injections, prevented the development of tolerance, increased analgesic latencies and abolished the difference between tested and nontested animals.
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D004361:Drug Tolerance; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000031:analogs & derivatives*; D009271:Naltrexone / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects*
D000700:Analgesics; D009270:Naloxone; D009271:Naltrexone; D009020:Morphine