<正> Immunoreactive substance P（Ir-SP）level

and substance P likeimmunoreactivity（SP-Li）in the spinal cord were observed with radioimmunoassay andimmunohistochemistry in rats after they were given an intraperitoneal injection of mor-phine（7.5mg/kg）or electroacupunctured（3V and 3Hz）on the “Jiaji point”.It wasfound that the pain threshold（PT）

Ir-SP level and SP-Li in the dorsal horn of the spi-nal cord were more significantly increased in the animals after the administration ofmorphine or electroacupuncture than in the control（P<0.05～0.01）.The combined effectsof morphine and electropacupuncture were even more powerful than either of the agentswas administered singly.Naloxone could block the analgesic effect and the elevation ofIr-SP due to morphine or electroacupuncture.The findings suggest that there is a synergismbe tween morphine and electroacupuncture and the analgesic effect of the 2 depends uponthe increase of Ir-SP level of the spinal cord mediated through the opiate receptors.