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
Objective: 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.
Methods: 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.
Results: 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).
Conclusions: 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.