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