Effect of electroacupuncture at "Zusanli" (ST36) and "Tianshu" (ST25) on intestinal function and autonomic nerve balance in rats with irritable bowel syndrome

Abstract

To study whether electroacupuncture (EA) of "Zusanli" (ST36) combined with "Tianshu" (ST25) has a synergistic effect in regulating the colonic function and autonomic nerve balance in rats with irritable bowel syndrome (IBS). Male Wistar rats were randomly divided into control, model, EA-ST36, and EA-ST36+ST25 groups, with 14 rats in each group. The IBS model was established by using water avoidance stress method. The visceral hypersensitivity was measured using the abdominal wall retraction reflex (AWR). The rectus abdominis electromyogram (EMG), intestinal electrical activity, and electrocardiogram (ECG) were recorded using a PowerLab data acquisition and analysis system. The contents of serum cAMP and cGMP were determined by ELISA, the expression levels of colonic tyrosine hydroxylase (TH) and choline acetyl-transferase (ChAT) proteins were determined by immunofluorescence staining and Western blot, respectively. Compared with the control group, the model group had an evident increase in the levels of AWR, LF, LF/HF, ChAT protein expression, cAMP and cGMP contents and cAMP/cGMP ratio (P<0.001, P<0.05), and a marked decrease in the levels of HF, frequency of slow waves of intestinal EMG, visceral pain threshold (PT), immunoactivity and expression of TH protein (P<0.05, P<0.001). In contrast to the model group, the levels of AWR, LF, LF/HF, ChAT protein expression and immunoactivity, cAMP and cGMP contents and ratio of cAMP/cGMP were significantly reduced (P<0.001, P<0.05, P<0.01), whereas the levels of frequency of slow waves of intestinal EMG, PT, and the immunoactivity and expression of TH were considerably increased (P<0.001, P<0.05) in both EA-ST36 and EA-ST36+ST25 groups. EA of both ST36 and ST36+ST25 can relieve visceral pain, and reduce sympathetic activity to improve autonomic nerve balance, but without apparent synergistic effect between EA-ST36 and EA-ST25 in rats with IBS.