Immunoreactive substance P (Ir-SP) level and substance P-like activity (SP-LI)in the spinal cord were determined with radioimmunoassay and immunohistochemistry in rats after they were given an intraperitoneal injection of morphine(7.5mg/kg)or electroacupunctured(3V and 3Hz)on the "Jiaji" point. It was found that pain threshold,Ir-SP content,and SP-LI activity in the dorsal horn of the spinal cord were significantly increased in the experimental group than in the control (P

Experimental methodssintraperitoneal injection of diazepam,r-aminobutyric acid (GABA) receptor antagonist (picrotoxin) and GABA synthesis inhibitor (iso-niazid) ;the pain threshold and serotonin ( 5 -HT) content in the brain are measured with spectrofluorometry.The effect of diazepam on ACTH analgesia (AA) is abstracted and the possible mechanisms of diazepam effect are studied.Results: diazepam increases the effect of AA.picroloxin and isoniazid reduce it and antagonize the analgesia effect of ACTH; diazepam increases the content of 5-HT in hipocampus,hypothalamus and midbrain;diazepam + ACTH increases,more than AC-TH or diazepam singly,the level of 5-HT in the 3 brain regions; picrotoxin and isoniazid reverse the effect of diazepam and ACTH on the content of 5-HT in the 3 brainsites; potentiation of diazepam on AA is antagonized by naloxone and atropine.