The Objective of the present experiment was to investigate if there was a relationship between the changes of the pain threshold and the content of glutamate and GABA in the caudate nuclei after electroacupuncture and excitation of the sensorimotor area I. The experiments were performed on Wistar rats of both sexes weighing 250-320g. The rats received electroacupuncture at Zusanli (ST36) and Huantiao (GB30) points (2mA, 6-20Hz) or excitation of the sensorimotor area I (topical application of glumate 0.5mM) for 30min. The cont6ots of glutamate and GABA were analyzed at 0, 30, 60, 90, l20, l80min by the method of microdialysis. In another group the withdrawal threshold was measured under the same treatment. The contents of glutheate were rnarkedly increased from 30 to 60min after excitation of the sensorimotor area I (P<0.05). The contents of glwtatC increased only at 0min after electroacupuncture. However the contents of GABA did not chang significantly after excitation sensorimotor area I or electroacupuncture..
　　The withdrawal threshold increased significantly after electroacupuncture and excitation of sensorimotor I from 0 to 15min, compared with the saline group and the binding group (P<0.05). The results suggest that there is a relationship between the changes of contents of glutamate but not GABA in the caudate nuclei and acupuncture analgesia, and there is no relationship between the changes of contents of glutamate and GABA and analgesia induced by excitation of sensorimotor area I.

　　Wu Guoji, Shi Hong, Chen Zhengqiu & Xu We.
　　Institute of Acupuncture, China Academy of TCM, Beijing 100700, China.