[Comparison of effects of electroacupuncture at "Dachangshu" (BL 25) or "Tianshu" (ST 25) on visceral sensitivity, c-kit and TRPV1 of irritable bowel syndrome rats].

Objective: To compare the effects of electroacupuncture (EA) at "Dachangshu" (BL 25) or "Tianshu" (ST 25) for visceral sensitivity, gene expression product c-kit of colonic Cajal interstitial cells (ICC) and capsaicin receptor 1 (TRPV1) of irritable bowel syndrome (IBS) rats, so as to investigate the effect and mechanism differences of EA at the back point and the front point of large intestine for IBS rats.

Methods: Forty-two Wistar neonatal rats were randomly divided into a blank group (9 rats) and a model group (33 rats). IBS model was established with mother and child separation, acetic acid enema in young rats and colorectal dilatation method. Twenty-seven IBS rats in life were randomly divided into a model control group, a Dachangshu group and a Tianshu group, 9 rats in each group. EA (disperse-dense wave, 2 Hz/100 Hz, 0.1-0.3 mA) for 20 min was used at "Dachangshu" (BL 25) and "Tianshu" (ST 25) respectively in the Dachangshu and Tianshu groups, once every other day, totally 5 times. The rats in the model control group were fixed with soft cloth sleeve for 20 min, without acupuncture. No intervention was used in the blank group. The stool property Bristol grading score was recorded before and after intervention in each group. The visceral sensitivity was evaluated by abdominal withdrawal reflex. The latency until the first systolic wave occurred and the number of systolic wave within 90 s were observed. Immunohistochemical was used to detect the positive expressions of c-kit and TRPV1, the ICC colon specific marker.

Results: Compared with the blank group, the Bristol score increased，latency period shortened, systolic wave number increased, c-kit and TRPV1 positive expressions increased in the model control group (all <0.01). Compared with the model control group, the Bristol score decreased, latency period increased, systolic wave number decreased, c-kit and TRPV1 positive expressions decreased after intervention in the Dachangshu and Tianshu groups (<0.05, <0.01). Compared with the Dachangshu group, the TRPV1 positive expression decreased after intervention in the Tianshu group (<0.05).

Conclusion: EA at "Dachangshu" (BL 25) or "Tianshu"(ST 25) can improve the diarrhea in IBS model rats, reduce the visceral sensitivity, and its mechanism may be related to regulating the expressions of colon c-kit and TRPV1. EA at "Tianshu" (ST 25) is more apparent for TRPV1 than at "Dachangshu" (BL 25).