For the purpose of elucidating the role of the cholinergic nervous system in the process of acupuncture analgesia

the content of acetylcholine(ACh)and the activity of acetylcholinesterase(ACHE)in different parts of the rabbit brain were estimated under electroacupuncture analgesia.ACh contentwas estimated with microbioassay method on toad rectus abdominis and the activity of AChE wasdetermined by Hestrin's colorimetric method.The points needled in rabbits were “Hegu”(L.I.4)and “Zusanli”(St.36).The experiments were done on 33 rabbits

and 33 rabbits were used as con-trols.After electroacupuncture induction the pain threshold of rabbits was significantly raised.At thistime the ACh content in the caudate nucleus and the cerebral cortex significantly decreased

whereasthe AChE activity in the caudate nucleus and cerebral cortex significantIy decreased

the AChE activityin caudate nucleus and hypothalamus however swhowed a significant increase.There were no suchsignificant differences of ACh content in e hypothalamus and AChE activity in the cerebral cortex.The results suggest that the cholinergic neurons in the central nervous system

especially in the caudate nucleus

may be an important factor taking part in the mechanism of acupuncture analgesia.