Analysis of composition of gut microbial community in a rat model of functional dyspepsia treated with Simo Tang

Abstract

Objective: To investigate composition of gut microbial community in a rat model of functional dyspepsia (FD) and to explore the interventional effects of Simo Tang (, SMT).

Methods: A rat model of FD was established through the tail-clamping stimulation method. The rat model of FD was assessed by the state of rats, their weight, sucrose preference rate, and intestinal propulsion rate. The DNA was extracted from stool samples after treatment with SMT. Amplified polymerase chain reaction (PCR) products of the 16S rDNA were sequenced using NovaseQ6000 after construction of libraries. Composition of gut microbial community in the stool samples was determined and analyzed by cluster analysis, bioinformatic analysis, and analysis of α-diversity and β-diversity.

Results: The rat model of FD was successfully established using the tail-clamping stimulation method. The statistical results of cluster analysis of operational taxonomic units (OTUs) showed that the relative abundance of OTUs in the FD group was the lowest, while it was the highest in the normal (N) group. The composition of microbiome in the four groups was similar at phyla level. Compared with the FD group, the abundance of Firmicutes was downregulated, and the abundance of Proteobacteria and Bacteroidetes was upregulated in the Simo Tang (SMT) and high-dose Simo Tang (SMT.G) groups. The ratio of Bacteroidetes/ Firmicutes was also elevated. According to the analysis of α-diversity and β-diversity, the abundance of flora in FD rats was significantly reduced. The treatment using SMT appeared beneficial to improve the diversity of flora. SMT could improve the intestinal flora in FD rats. The results showed that FD rats had intestinal flora imbalance, and species diversity increased. The results suggested that SMT could regulate the disorders of intestinal flora caused by FD.

Concludions: SMT could restore gut homeostasis and maintain gut flora diversity by modulating the gut microbiota and its associated metabolites in rats, thereby treating gastrointestinal diseases.

Keywords: Simo Tang; abundance of flora; functional dyspepsia; gastrointestinal microbiome; gut microbial community composition.

Figure 1. Establishment of a rat model of FD and the intervention effect of SMT

A: trends of body weight in rats; B: sucrose preference rate; C: intestinal propulsion rate. N group: SD rats without treatment (n = 3); FD group: SD rats using a tail clamping stimulation method (n = 3); SMT.G group: model SD rats were fed with SMT (6 g/kg) per day (n = 3); SMT group: model SD rats were fed with SMT (3 g/kg) per day (n = 3). FD: functional dyspepsia, SMT: Simo Tang; SD: Sprague-Dawley. Data are presented as the mean ± standard deviation using one-way analysis of variance (n = 3). ^aP < 0.01, compared with the N group; ^bP < 0.01, ^cP < 0.05, compared with the FD group.

Figure 2. Clustering of OTUs

A: relative abundance of OTUs in the four groups; B: dilution curve of all samples; C: Venn diagram. OTU: operational taxonomic units; SD: Sprague-Dawley. N group: SD rats without treatment (n = 5); FD group: SD rats using a tail clamping stimulation method (n = 4); SMT.G group: model SD rats were fed with SMT (6 g/kg) per day; SMT group (n = 5): model SD rats were fed with SMT (3 g/kg) per day (n = 4).

Figure 3. SMT modulated intestinal bacterial composition in the rat model of FD

A: analysis of bacterial composition in different groups at phylum level; B: comparison of the Ace index; C: comparison of the Chao1 index; D: comparison of the Shannon index; E: comparison of the Simpson index; F: principal coordinates analysis based on weighted Unifrac distances. FD: functional dyspepsia, SMT: Simo Tang; SD: Sprague-Dawley. N group: SD rats without treatment (n = 5); FD group: SD rats using a tail clamping stimulation method (n = 4); SMT.G group: model SD rats were fed with SMT (6 g/kg) per day (n = 5); SMT group: model SD rats were fed with SMT (3 g/kg) per day (n = 5). Data are presented as the mean ± standard deviation using one-way analysis of variance (n = 4-5). ^aP < 0.01: compared with the N group; ^bP < 0.05: compared with the N group; ^cP < 0.05: compared with the FD group.

Figure 4. LEfSe analysis of microbiota in different groups

A: LEfSe identified the most differentially abundant bacterial taxa in different groups. LDA threshold > 4 is shown; B: taxonomic cladogram obtained from LEfSe analysis of 16S rDNA sequences. LefSe: Linear discriminant analysis effect size; SD: Sprague-Dawley. N group: SD rats without treatment (n = 5); FD group: SD rats using a tail clamping stimulation method (n = 5); SMT.G group: model SD rats were fed with SMT (6 g/kg) per day (n = 4); SMT group: model SD rats were fed with SMT (3 g/kg) per day (n = 4).