Effects of parenteral morphine and oral methadone on self-stimulation in the rat.
Facilitation of self-stimulation has been reported following the administration of various opiates. Methadone, a synthetic narcotic used in the treatment of narcotic addiction, has recently been demonstrated to facilitate self-stimulation when administered parenterally. The present study examined the effects of orally administered methadone (20 and 30 mg/kg), the route of administration used clinically, on MFB-LH self-stimulation at 2.5, 5, 8, 12, 17, and 24 hours post-administration. Reliable facilitation was observed at 2.5 hours post-administration. However, the effect of methadone was less pronounced than that observed with a dose of parenteral morphine which was approximately equivalent in terms of analgesic potency.
D000284:Administration, Oral; D000818:Animals; D004558:Electric Stimulation; D007274:Injections, Intraperitoneal; D008297:Male; D008691:Methadone / Q000008:administration & dosage / Q000494:pharmacology*; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012653:Self Stimulation / Q000187:drug effects*
D009020:Morphine; D008691:Methadone