Electroacupuncture at Acupoint ST-36 Promotes Contractility of Distal Colon via a Cholinergic Pathway in Conscious Rats

Purpose To investigate the effects and possible mechanism of electroacupuncture (EA) at acupoint ST-36 (Zusanli) on the contractility of the distal colon in conscious rats. Methods Rats were randomized into four groups, including the ST-36 group, the sham group, the saline-plus-ST-36 and the atropine-plus-ST-36 group. Needles were inserted into the acupoints for EA. The distal colonic contractility was measured with a manometric catheter inserted into the distal colon. The colonic contractility was recorded for 1 h before EA, 20 min during EA, and 3 h after EA. Saline or atropine was administrated in the saline-plus-ST-36 or atropine-plus-ST-36 group. Results (1) EA at ST-36 significantly increased the contractility of the distal colon. The mean AUC during and after EA were significantly higher than that before EA in the ST-36 group, a 27% increase during EA and 26% after EA. (2) Atropine abolished the accelerating effect of EA at ST-36. The mean AUC remained unchanged during or after EA compared with that before EA in the atropine-plus-ST-36 group. Conclusions EA at ST-36 has a stimulatory effect on the contractility of the distal colon in conscious rats, and the stimulatory effect may be mediated via the cholinergic pathway.