title: Cross-tolerance to metkephamid (LY127623) produced by morphine solution ingestion by mice.
abstract: The effects of morphine and metkephamid were determined on the writhing test in drug-naive mice and mice that had been exposed to morphine solutions as their sole fluid source for a 5- or 7-day period. The average dose of morphine consumed was 435 mg/kg, using either 0.5 mg/ml solution for 7 days or a 1 mg/ml solution for 5 days. The ingestion of these morphine solutions produced a marked tolerance to the analgesic effects of morphine and cross-tolerance to the analgesic effects of metkephamid.
mesh_terms: D000698:Analgesia; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D051379:Mice; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000187:drug effects; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu
chemical_list: D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D004744:Enkephalin, Methionine; D009020:Morphine; C028208:metkephamid