title: Indirect and direct suppressive actions of morphine on dorsal horn neurons in rabbits.
abstract: The analgesic mechanism of morphine on the spinal nociceptive transmission was compared in rabbits with the intact and cold-blocked states of the spinal cord. The degree of the suppressive effect of morphine (2 mg/kg) on the bradykinin-induced activity was significantly greater in the intact than in the cold-blocked states. Morphine (4 mg/kg) suppressed the nociceptive responses to similar levels in both states. These results suggest that in a small dose, the indirect suppressive action is more important than the direct action. In a larger dose, the suppressive action is probably exerted primarily by the direct spinal action.
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D003864:Depression, Chemical; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D013116:Spinal Cord / Q000187:drug effects*
chemical_list: D009020:Morphine; D001920:Bradykinin