Chang-Kang-Fang ameliorates irritable bowel syndrome with diarrhea in rat by regulating gut microbiota and improving intestinal barrier

Chang-Kang-Fang formula (CKF), a multi-herb traditional Chinese medicinal formula, has been clinically used for treatment of irritable bowel syndrome with diarrhea (IBS-D).Though we have reported the compounds of CKF and their therapeutic effect on IBS-D rats, the exact underlying mechanism is still not clear.The aim of this study was to clearly define the effect of CKF on IBS-D by regulating gut microbiota and promoting intestinal barrier.IBS-D rats were established by psychosocial stress (restraint) combined with the peripheral stimulation (senna leaf gavage) stress.The changes of body weight and the number of fecal pellets were investigated during the experiment.The effect on intestinal sensitivity was assessed based on the abdominal withdrawal reflex (AWR) scores and the intestinal permeability, the expression of zona occludens 1 (ZO-1), measured by immunohistochemistry.The composition of gut microbiota was detected through 16S rRNA.The administration of CKF significantly had therapeutic effects on IBS-D rats based on the decreased AWR scores and the increased number of pellets.However, the changes of body weight were not observed.In addition, CKF could up-regulate the expression of ZO-1 in the colon and rebalance the gut microbiota of IBS-D by increasing the abundance of Lactobacillus, Allobaculum, Roseburia, and Lachnospiraceae_NK4A136. CKF potentially alleviated IBS-D through regulating gut microbiota and improving the intestinal barrier function.