Tolerance develops to spinal morphine analgesia but not morphine-induced convulsions.
Administration of morphine into the spinal intrathecal (i.t.) space produced dose-dependent analgesia in the mouse. At higher doses i.t. morphine induced seizures of the hindlimbs. Mice treated chronically with morphine (75 mg pellet, s.c.) for 72 h were tolerant to the analgesic effects of i.t. morphine, but not to the proconvulsant action. Spinal morphine analgesia was attenuated by naloxone, whereas i.t. morphine-induced seizures were not. These results indicate that spinal opioid receptors mediate analgesia but not seizures following i.t. morphine treatment in the mouse.
Yoburn
B C
BC
Department of Pharmaceutical Sciences, College of Pharmacy and Allied Health Professions, St. John's University, Queens, NY 11439.
Lutfy
K
K
Sierra
V
V
Tortella
F C
FC
D000698:Analgesia; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D007278:Injections, Spinal; D008297:Male; D051379:Mice; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D012640:Seizures / Q000139:chemically induced* / Q000503:physiopathology; D013116:Spinal Cord / Q000187:drug effects
D009292:Narcotic Antagonists; D009270:Naloxone; D009020:Morphine