In order to investigate whether enteric nervous system is involved in electroacupuncture analgesia

64 Sprague-Dawley were randomly divided into four groups

control group

electroacupuncture (EA) group given electroacupuncture at bilateral "Futu" and "Zusanli" points

acute inflammatory visceral pain(VP) induced by injection of formalin into the colon wall and EA + VP group. The changes of density of nitric oxide synthase(NOS)-

acetylcholinesterase (AChE ) - positive neuronal celf body and fiber in rat colon and ilioceacal valve were observed by histochemical method. Results indicate that formalin induced evident visceral pain response

the pain score in EA+ VP group was significantly smaller than that in VP group (P < 0. 01 ). The densities of NOS-

AChE-positive neuronal cell body and fiber of colon and ilioceacal valve in EA group were significantly smaller than those in control group(P < 0. 01

P < 0. 05 )

on the contrary

the densities of NOS-

AChE-positive neuron and fiber in the colon and ilioceacal valve in VP group were significantly greater than those in control group(P < 0. 01

P < 0. 05 )

and which in VP + EA group were smaller than those in VP group(P < 0. 01

P < 0. 05 ). The results suggest that nitrergic neuron and cholinergic neuron of the enteric nervous system are involved in the electroacupuncture anti-acute inflammatory visceral pain.