title: Possible physiological control of morphine analgesia in mice.
abstract: Several laboratories have reported that dynorphin and vasopressin may be present in the same neurons and released together in a fixed ratio. In this study, we report that vasopressin and dynorphin can regulate morphine-induced analgesia in the mouse tail-flick test. Its action is opposite that observed for dynorphin because, when administered simultaneously with morphine, vasopressin in a dose-related manner potentiated morphine-induced analgesia while dynorphin antagonized it. When vasopressin and dynorphin is administered together with morphine, morphine ED50 returned to control level.
mesh_terms: D000698:Analgesia; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology / Q000502:physiology; D004347:Drug Interactions; D004399:Dynorphins; D004723:Endorphins / Q000494:pharmacology / Q000502:physiology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology
chemical_list: D004723:Endorphins; D001127:Arginine Vasopressin; D004399:Dynorphins; D009020:Morphine