Antagonism by naloxone of morphine-induced single-dose dependence and antinociception in mice.
Single-dose physical dependence on morphine, as indicated by the mouse withdrawal jumping test, was reduced in a dose-related fashion by co-administration of naloxone. In the same dose range, naloxone also antagonized the antinociceptive effect of morphine in the mouse writhing test. Dose-response data revealed essentially the same ED50's for naloxone in both tests. These results indicate that naloxone does indeed block the development of morphine-induced single-dose physical dependence in mice and that it does so as effectively as it blocks morphine-induced inhibition of writhing.
D000701:Analgesics, Opioid / Q000037:antagonists & inhibitors*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D051379:Mice; D009020:Morphine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology*; D013375:Substance Withdrawal Syndrome / Q000517:prevention & control; D019966:Substance-Related Disorders / Q000517:prevention & control*
D000701:Analgesics, Opioid; D009270:Naloxone; D009020:Morphine