[Effect of Gegen Qinlian Decoction on gut microbiota of irritable bowel syndrome with diarrhea rats].

This study aims to explore the effect of Gegen Qinlian Decoction on gut microbiota of irritable bowel syndrome with diarrhea(IBS-D) rats. A total of 36 male SD rats were randomly classified into the control group, model group, rifaximin group(150 mg·kg~(-1)), and high-dose(8.125 g·kg~(-1)), medium-dose(4.062 5 g·kg~(-1)) and low-dose(2.031 3 g·kg~(-1)) Gegen Qinlian Decoction groups with the random number table method, 6 in each group. After modeling, rats were treated for 8 days. The general state, bristol stool chart(BSC) score, and the minimum volume threshold for abdominal withdrawal reflex were recorded. Pathological changes of colon tissues were observed based on hematoxylin and eosin(HE) staining, and gut microbiota was analyzed based on 16 S rRNA sequencing. Compared with the model group, rifaximin group and high-dose and medium-dose Gegen Qinlian Decoction groups showed low BSC score(P<0.01) and high minimum volume threshold for abdominal lifting(P<0.05). HE staining showed that Gegen Qinlian Decoction could relieve intestinal inflammation. 16 S rRNA sequencing suggested obvious variation of gut microbiota in IBS-D rats. Gegen Qinlian Decoction significantly raised the richness index and diversity index of gut microbiota, regulated the number of the flora, and improved alpha diversity and beta diversity. Species composition of gut microbiota and LEfSe analysis showed that Gegen Qinlian Decoction could significantly increase the ratio of Bacteroidota to Firmicutes, elevate the abundance of probiotics such as Clostridia and Lachnospirales, and reduce the abundance of conditional pathogens such as Bacteroidales, and Prevotellaceae. PICRUSt2 analysis indicated that Gegen Qinlian Decoction was mainly related to multiple metabolic pathways such as carbohydrate metabolism and amino acid metabolism. In summary, Gegen Qinlian Decoction can significantly reduce visceral hypersensitivity of IBS-D rats, alleviate intestinal inflammation, and relieve clinical symptoms such as diarrhea. The mechanism is the likelihood that it regulates the composition and structure of gut microbiota and improves its metabolic pathway as well.