[Effect of Electroacupuncture at "Yintang" (GV 29) and "Tianshu" (ST 25) on the Ethology and the Expression of TRPV 1 Receptor in Colon of Irritable Bowel Syndrome Rats].

Objective: To observe the ethology and expression of transient receptor potential vanilloid-1(TRPV 1) in colon of irritable bowel syndrome (IBS) rats treated by electroacupuncture (EA) at "Yintang" (GV 29) and "Tianshu" (ST 25), so as to explore the different effectiveness of different acupoints and its related mechanism underlying improvement of the symptoms of somatopsychic illness.

Methods: Thirty-two neonatal Wistar rats were randomly divided into blank control group, model group, Yintang (GV 29) group, and Tianshu (ST 25) group (=8 in each group). IBS model was established by neonatal maternal separation and acetic acid enema combined with colon and rectum expansion stimulation. Rats of the GV 29 and ST 25 groups were given EA treatment at age of 9 weeks old, 20 minutes, once every other day for 5 times. Latency of the 1 time contraction wave and numbers of contractive wave in 90 s were recorded to evaluate abdominal visceral sensitivity by abdominal withdrawal reflex. Horizontal and vertical movements were observed to assess the emotional and psychological behavior of rats by open field test. TRPV 1 expression in colon was detected by immunohistochemistry method.

Results: Compared with the black control group, latency of the 1 time contractive wave was significantly shortened and the wave numbers in 90 s were increased significantly in the model group (<0.01), while the numbers of vertical and horizontal movements were also significantly reduced (<0.01), accompanied with increased TRPV 1 expression in the colon (<0.05). Compared with the model group, After EA intervention, the levels of the above-mentioned 5 indexes were significantly reversed in the GV 29 and ST 25 groups (<0.01,<0.05), except the number of horizontal movement in the ST 25 group (>0.05). The expression level of TRPV 1 was significantly lower in the ST 25 group than in the GV 29 group (<0.01).

Conclusions: EA at GV 29 and ST 25 can alleviate the abdominal pain and improve the mental and emotional disorders in IBS rats. GV 29 has a better effect on relieving the depressive-like psychoemotional behavior of IBS rats, while ST 25 is more effective in treating abdominal pain. There is significantly different influence on TRPV 1 expression in colon between these two treatment groups, which may contribute to their different effect in pain relieving.