ELECTRICAL STIMULATION OF HYPOTHALAMIC ARCUATE NUCLEUS (ARC) CAN CHANGE RESPONSES TO ELECTROACUPUNCTURE OF NEURONS OF DORSAL RAPHE NUCLEUS (DR) AND LOCUS COERULEUS (LC)

116 DR units and 104 LC units were extraccllul-arly recorded in 111 paralyzed and artificially ventilat-ed rats.The main results were as follows:Both DRand LC units exhibited excitatory,inhibitory or noresponse to ARC stimulation or electroacupuncture(EA) on Zusanli (St 36) and Sanyinjiao (Sp 6).After ARC stimulation,the number of EA-excitedDR units and EA-inhibited LC units were increasedsignificantly.Further,the post-EA discharge ratewas increased in DR units and decreased in LC units.The above-mentioned reciprocal effects of ARC sti-mulation on DR and LC units could be simultaneou-sly observed in the same rat.Naloxone (1 mg/kgi.p.) increased the spontaneous discharges of DR andLC units and reversed the effects of ARC stimula-tion.The results indicated that under physiologicalcondition the endogenous opiate-like substances mayhave a tonic inhibitory effect on the DR and LCneurons,and that ARC might participate in the EAanalgesia via changing the responses of DR and LCneurons to EA,in which opiate-like substances (pro-bably,β-endorphin) are involved.