[Electroacupuncture of "Tianshu" (ST 25) Suppresses Visceral Pain Possibly by Down-regulating Mast Cell Activation, and Tryptase and SP Expression in Rats with Post-infectious Irritable Bowel Syndrome].

OBJECTIVE: To observe the effect of electroacupuncture (EA) at "Tianshu" (ST 25) on visceral pain and colonic mast cell (MCs) number and tryptase and SP expression in post-infectious irritable bowel syndrome (PI-IBS) rats, so as to reveal its mechanisms underlying improvement of PI-IBS. METHODS: Forty-five female Wistar rats were randomly divided into control, model and EA groups (15 rats/ group, 3 rats/group used for H. E. staining, and 12 rats/group for immunohistochemistry). The PI-IBS model was established by intra-anal injection of mixed liquor of 50% ethyl alcohol and trinitro-benzene-sulfonic acid (TNBS). EA (2 Hz/15 Hz, 0.5-1.0 mA) was applied to bilateral "Tianshu" (ST 25) for 30 min, once every day for 14 days. The visceral pain was measured by abdominal withdrawal reflex (AWR), for which the rectal implanted air balloon was dilated by infusion of normal saline. The histopathological changes of the colon tissue were observed after H. E. staining, and the colonic MCs were displayed by Toluidine blue staining. The expression of tryptase and SP proteins in the colon specimens were detected by immunohistochemistry. RESULTS: <0.05). CONCLUSION: EA of "Tianshu" (ST 25) can inhibit visceral pain in PI-IBS rats, which may be associated with its effects in activating MCs and down-regulating the expression of tryptase and SP proteins in the colonic tissues.