Shenlian (SL) Decoction, a Traditional Chinese Medicine Compound, May Ameliorate Blood Glucose via Mediating the Gut Microbiota in db/db Mice

Abstract

Shenlian (SL) decoction is a herbal formula composed of Coptis and ginseng, of which berberine and ginsenoside are the main constituents. Even though SL decoction is widely used in treating diabetes in China, the mechanism of its antidiabetes function still needs further study. Gut microbiota disorder is one of the important factors that cause diabetes. To explore the effect of SL decoction on intestinal microbiota, gut microbiota of mice was analyzed by sequencing the gut bacterial 16S rRNA V3+V4 region and metagenomics. In this study, results demonstrated that SL decoction had a better hypoglycemic effect and β cell protection effect than either ginseng or Coptis chinensis. Alpha diversity analysis showed that all interventions with ginseng, Coptis, and SL decoction could reverse the increased diversity and richness of gut microbiota in db/db mice. PCoA analysis showed oral SL decoction significantly alters gut microbiota composition in db/db mice. 395 OTUs showed significant differences after SL treatment, of which 37 OTUs enriched by SL decoction showed a significant negative correlation with FBG, and 204 OTUs decreased by SL decoction showed a significant positive correlation with FBG. Results of KEGG analysis and metagenomic sequencing showed that SL decoction could reduce the Prevotellaceae, Rikenellaceae, and Helicobacteraceae, which were related to lipopolysaccharide biosynthesis, riboflavin metabolism, and peroxisome, respectively. It could also upregulate the abundance of Bacteroidaceae, which contributed to the metabolism of starch and sucrose as well as pentose-glucuronate interconversions. In the species level, SL decoction significantly upregulates the relative abundance of Bacteroides_acidifaciens which showed a significant negative correlation with FBG and was reported to be a potential agent for modulating metabolic disorders such as diabetes and obesity. In conclusion, SL decoction was effective in hypoglycemia and its mechanism may be related to regulating gut microbiota via upregulating Bacteroides_acidifaciens.

Figure 1

Effects on (a) FBG, (b) body weight, and (c, d) HOMA-IR. Immunohistochemistry of insulin in islet tissue. ^∗P < 0.05 vs. DC group; ^∗∗P < 0.01; ^∗∗∗P < 0.001.

Figure 2

Alpha diversity analysis of bacterial relative abundances. (a) Sobs, (b) Shannon, and (c) coverage diversity curves of gut microbiota community, which reflect the richness, diversity, and coverage of the community, respectively. Comparisons among different groups on (d) Sobs and (e) Shannon of gut microbiota were significant. ^∗P < 0.05; ^∗∗P < 0.01.

Figure 3

(a) Principal coordinate analysis (PCoA) of gut microbiota for mice. Weighted UniFrac PCoA plot and based on OTU abundance, each point represents the placenta microbiota of a sample, with main principal component (PC) scores: PC1 = 33.52% and PC2 = 13.26%. (b) The boxplot represents the dispersion of distribution of different groups of samples on PC1. Relative abundance of phylum level was significantly different among (c) NC, (d) Met, (e) RS, (f) HL, (g) SL, and DC groups, ^∗P < 0.05, ^∗∗P < 0.01, compared with the DC group.

Figure 4

Significantly different between DC and SL groups of gut microbial community at the (a) family level, (b) genus level, and (c) OTU level. ^∗P < 0.05 and ^∗∗P < 0.01, compared with the DC group. (d) Heatmap analysis indicating Spearman correlation between gut microbiota community and FBG on the family level, correlation R values, and P values were obtained by calculation; ^∗P < 0.05 and ^∗∗P < 0.01; R values were shown in different colors in the diagram.

Figure 5

Circos diagram of the KEGG pathways enrichment analysis, the left half circle represents the function abundance composition of the group, and the right half circle represents the distribution ratio of the function.

Figure 6

(a) KEGG analysis of differentially expressed genes between DC and SL groups. ^∗P < 0.05 and ^∗∗P < 0.01, compared with the DC group. (b) Correlation heatmap between KEGG analysis and FBG in db/db mice, the shades of color represent the richness of the function; correlation R values and P values were obtained by calculation; ^∗P < 0.05 and ^∗∗P < 0.01; R values were shown in different colors in the diagram.

Figure 7

Barplot of species and functional contribution analysis indicates the dominant species composition of a particular function.

Figure 8

Significance test of difference of Bacteroidaceae, Prevotellaceae, Rikenellaceae, and Helicobacteraceae among each group, ^∗P < 0.05; ^∗∗P < 0.01; ^∗∗∗P < 0.001, compared with the DC group.