Introduction: Gegen Qinlian Decoction (GQD) is a Chinese herbal medicine that has been reported to significantly decrease blood glucose levels, which is suggested to be related to interactions with the gut microbiota. However, the protective effect of GQD on intestinal barrier function with regard to its influence on the gut microbiota has not been explored to date. In this study, we investigated the role of the gut microbiota in mediating the hypoglycemic mechanism of GQD in type 2 diabetes mellitus (T2DM) rats.
Methods: The T2DM rats were randomly allocated to receive GQD, metformin (Met), or distilled water for 12 consecutive weeks, and changes in metabolic parameters, intestinal barrier function, and inflammation were investigated. Gut microbiota were analyzed using 16S rRNA sequencing from fecal samples, and statistical analyses were performed to correlate microbiota composition with phenotypes of the T2DM rats.
Results: Both GQD and Met administration decreased the levels of blood glucose and inflammatory factors, and increased the levels of tight junction proteins. However, GQD had a greater protective effect on islet function, restoring intestinal permeability, and inhibiting inflammation than Met, as evidenced by improvements in the levels of occludin and claudin-1 in the colon, and the expressions of serum inflammatory factors. In addition, GQD regulated the structure of the gut microbiota by increasing the proportions of short-chain fatty acids-producing and anti-inflammatory bacteria, and decreasing the proportions of conditioned pathogenic bacteria associated with the diabetic phenotype.
Conclusion: GQD could ameliorate hyperglycemia and protect islet function by regulating the structure of the gut microbiota, thereby restoring intestinal permeability and inhibiting inflammation in T2DM rats. Our study thus suggests that the hypoglycemic mechanism of GQD is mediated by its modulation of the gut microbiota.
J. Tian: None. M. Li: None. X. Tong: None.
National Natural Science Foundation of China (81430097); China Association for Science and Technology (CACM-2017-QNRC1-02)