INDIRECT AND DIRECT DEPRESSIVE EFFECTS OF MORPHINE ON ACTIVATION OF LAMINA V CELL OF SPINAL DORSAL HORN INDUCED BY INTRA-ARTERIAL INJECTION OF BRADYKININ

  • 1 January 1976
    • journal article
    • research article
    • Vol. 221  (1) , 96-104
Abstract
Small doses of morphine (0.3-20 mg/kg i.v.) inhibited, in the majority of intact rabbits, the unitary activities of the lumbar lamina V dorsal horn neurons induced by intra-arterial injection of bradykinin, a potent pain producing substance, but not in spinal rabbits. A large dose of morphine (5.0 mg/kg), inhibited the bradykinin-induced response even in spinal rabbits. Morphine, in small doses, may inhibit the sensory transmission of bradykinin-induced pain at the dorsal horn of the spinal cord, through its facilitatory action on the decending inhibitory mechanism; in large doses the level of dorsal horn is directly inhibited.