The Chinese Herbal Formula Shenzhu Tiaopi Granule Results in Metabolic Improvement in Type 2 Diabetic Rats by Modulating the Gut Microbiota

OBJECTIVE: The aim of this study is to investigate the implication of the Chinese herbal formula (CHF) Shenzhu tiaopi Granule (STG) in type 2 diabetes mellitus (T2DM) and discuss the mechanisms by which STG regulates the gut microbiota. METHOD: Goto-Kakizaki (GK) rats and age-matched Wistar (W) rats were acclimatized for 1 week. The GK rats were randomly divided into 3 groups and orally gavaged with saline (model group, M), acarbose (acarbose group, A), and STG (granule of CHF group, G; the component of this formula includes Codonopsis pilosula, Rhizoma Atractylodis, Pinellia, Poria cocos, Pericarpium Citri Reticulatae, Coptis chinensis Franch, and Pueraria). The W rats were orally gavaged with saline (control group, C). The observation time was 8 weeks. The weight, fasting blood glucose (FBG) level, and blood lipid levels were tested. The 16S rRNA genes in the V3-V4 region were sequenced, and the structure of the gut microbiota was analysed. RESULTS: Compared to C, M displayed significant differences in blood glucose, gut microbiota, etc. (P<0.05; P<0.01). Compared to M, A and G showed a similar reduction in the FBG gain and a shift in the structure of the gut microbiota (P<0.05; P<0.01). Compared with A, G exhibited a significant decrease in weight, FBG level, and total cholesterol (P<0.05). The gut microbiota, Bacteroidetes, the Firmicutes/Bacteroidetes ratio, Allobaculum, and Desulfovibrionaceae were significantly decreased in response to the STG treatment, while Lactobacillus was significantly enriched (P<0.05; P<0.01). The community composition also differed at the phylum and genus levels based on the linear discriminant analysis effect size and heat map. CONCLUSION: Our findings suggest that the composition of the gut microbiota was significantly changed in the diabetic GK rats compared with that in the normal W rats. STG treatment can improve glucose and lipid levels and modulate the gut microbiota in T2DM rats.