[Effect of electroacupuncture on colonic motility and RhoA and ROCK protein expression in IBS-D rats]

To observe the effect of electroacupuncture (EA) of "Tianshu"(ST25) and "Shangjuxu"(ST37)on gastrointestinal motility, psychological abnormality and expression of RhoA and ROCK protein in rats with diarrhea predominant irritable bowel syndrome (IBS-D), so as to explore its underlying mechanism in improving IBS-D.

Thirty-six male rats were randomly and equally divided into control, model, EA and medication groups (n=9 in each group). The IBS-D model with psychological abnormality was established by gavage of dinitrobenzene sulfonic acid (DNBS) + chronic restraint stress. EA (2 Hz/100 Hz, 0.3 mA) was applied to bilateral ST25 and ST37 for 20 min, once a day for 7 days. Rats of the medication group received gavage of pinaverium bromide solution (15 mg/kg), once a day for 7 days. The rats' food intake in 24 h, body mass and colonic contraction waves were recorded. The anhedonia-related behavior was measured using the sucrose consumption test. The elevated plus maze test (the open-arm residence time ratio) was used to assess the anxiety-like behavior. The small intestinal propulsion rate test was used to assess the intestinal motility. The expression levels of RhoA and ROCK proteins in the colonic tissue were measured by Western blot.

After modeling, the body mass, food consumption, sucrose preference index, the open-arm residence time ratio andlatency of colonic contraction waves were significantly decreased (P<0.05), and the number of contraction waves, intestinal propulsive rate, and the expression levels of RhoA and ROCK proteins considerably increased (P<0.01，P<0.05) in the model group relevant to the control group. Following the interventions, the decrease of body mass, food consumption, sucrose preference index, open-arm residence time ratio and latency of contraction waves, and the increase of the contraction waves, intestinal propulsive rate, and the expression levels of RhoA and ROCK proteins were all reversed by both EA and medication (P<0.05，P<0.01). The effect of EA was significantly superior to that of medication in increasing the sucrose pre-ference index (P<0.05).

EA can improve both colonic motility and psychological disorders in IBS-D rats with psychological disorder, which may be related to its function in down-regulating the expression of colonic RhoA and ROCK proteins.