Ameliorating effects of electroacupuncture on the low-grade intestinal inflammation in rat model of diarrhea-predominant irritable bowel syndrome

Background and Aim We aim to investigate the effects and mechanisms of electroacupuncture (EA) at ST25 and ST37 on the intestinal low-grade inflammation (LGI) in rat model of Diarrhea-predominant irritable bowel syndrome (IBS-D). Methods IBS-D model rats were established by acetic acid enema combined with restraint and tail clamping. Before EA intervention, they were divided into three groups: blank 1 group, blank 2 group, and IBS-D model group. Diarrhea symptoms and visceral pain sensitivity were evaluated. After constructed the model successfully, the remaining IBS-D model group rats were randomly divided into model group and EA group. Local intestinal inflammation (HE staining), changes of intestinal mucosa (occludin protein and microvascular diameter) were evaluated. Differences between two groups were compared using t-test or Mann-Whitney U-test. Differences among more than two groups were compared using one-way ANOVA or Kruskal-Wallis test. Results After modeling, the results of HE staining in intestinal tract of IBS-D model rats showed LGI. Compared with the model group, 4 h fecal moisture content (diarrhea index) and the AWR score were decreased in the EA group. The results of HE in EA group showed that the infiltration of intestinal inflammatory cells were alleviated. Additionally, EA significantly upregulated the expression of occludin protein and partially dilated the intestinal microvascular diameter. Pearson correlation analysis showed that the symptoms of IBS-D rats were correlated with the changes of intestinal mucosa. Conclusion EA may treat intestinal LGI in IBS-D rats by upregulating the expression of occludin protein and dilating the intestinal microvascular diameter.