Electroacupuncture improves intestinal function by down-regulating expression of 5-HT1AR and c-fos proteins in the hypothalamus and colon tissues via brain-gut axis in rats with functional diarrhea

Abstract

To observe the effect of electroacupuncture (EA) on expression of 5-HT1A receptor (5-HT1AR) and c-fos proteins in the hypothalamus and colon tissues in functional diarrhea (FD) rats so as to explore its underlying mechanisms in improving intestinal function via brain-gut axis. A total of 40 SD rats were randomized into blank control, model, EA Tianshu (ST25)-Dachangshu (BL25, ST25-BL25) and EA Quchi (LI11)- Shangjuxu (ST37, LI11-ST37) groups. The FD model was established by gavage of Folium Sennae (10 mg/kg) and constraint immobilization once daily for 29 days. EA (10 Hz/50 Hz, 1.5 mA) was applied to bilateral ST25 and BL25 in EA ST25-BL25 group, and bilateral LI11 and ST37 in EA LI11-ST37 group for 20 min, once daily for successive 10 days. The expression of 5-HT1AR and c-fos protein in the hypothalamus and colon tissues was determined by using Western blot. The state of stool was recorded for calculating the loose stool rate and diarrhea index. After modeling, the loose stool rate, diarrhea index and expression levels of 5-HT1AR and c-fos proteins in the colon and hypothalamus tissues were obviously increased in the model group in contrast with the blank control group(P<0.01，P<0.05). Following EA intervention, the loose stool rate and diarrhea index, the expression levels of 5-HT1AR and c-fos proteins in the hypothalamus and colon in the EA ST25-BL25 group, and the expression of 5-HT1AR in the colon in the EA LI11-ST37 group were significantly down-regulated relevant to the model group (P<0.01，P<0.05). No significant changes were found in loose stool rate and diarrhea index，and the expression levels of hypothalamic 5-HT1AR and hypothalamic and colonic c-fos proteins in the EA LI11-ST37 group (P>0.05). The expression levels of 5-HT1AR protein in the hypothalamus and c-fos protein in the hypothalamus and colon in the EA LI11-ST37 group were significantly up-regulated relevant to the EA ST25-BL25 group (P<0.05). EA of ST25-BL25 can down-regulate expression of 5-HT1AR and c-fos proteins in the hypothalamus and colon tissue in FD rats, which may contribute to its function in improving symptoms of FD possibly via brain-gut axis.