性激素变化对小鼠肠道菌群构成的影响

肠道菌群在维持宿主免疫和消化系统功能方面发挥着重要作用,肠道菌群的多样性和丰富度是衡量宿主健康状况的重要生理指标。性激素对动物生长发育发挥重要作用,但其对肠道菌群构成影响的相关实验研究相对较少。本研究以模式生物小鼠（Mus musculus）为对象,探究性激素的变化对小鼠肠道菌群构成的影响。采用外科手术方式建立小鼠去势模型,通过16S r RNA高通量测序技术,研究性激素对小鼠肠道菌群构成的影响。研究结果表明,雌性小鼠和雄性小鼠去势后,性激素水平显著下降。肠道菌群在门水平上,正常小鼠和去势小鼠肠道细菌群落均由拟杆菌门（Bacteroidetes）、厚壁菌门（Firmicutes）、变形菌门（Proteobacteria）、埃普西隆杆菌门（Epsilonbacteraeota）、髌骨细菌门（Patescibacteria）、放线菌门（Actinobacteria）、软壁菌门（Tenericutes）、脱铁杆菌门（Deferribacteres）、酸杆菌门（Acidobacteria）和蓝藻细菌门（Cyanobacteria）组成,主要菌群为厚壁菌门和拟杆菌门物种,两门占物种相对丰度百分比...

Effects of the Changes of Sex Hormones on Gut Microbiota Composition of Experimental Mice

[Objectives] Gut microbiota plays an important role in immune function and gastrointestinal system. The diversity and richness of gut microbiota are important physiological index to measure host health. Sex hormones play an important role on the growth and development of animals, but the effect of sex hormones on gut microbiota composition is not clear. [Methods] In this study, a mouse (Mus musculus) castration model was established by surgical method, fresh fecal samples of mice were continuously observed and collected during feeding, and the effects of sex hormones on the intestinal flora of mice were studied by 16S rRNA high-throughput sequencing technology. Usearch was applied to cluster reads with similarity above 97.0% and generate OTUs. Taxonomic annotations of feature sequences were processed by Bayesian classifier using SILVA as reference database. Statistics on composition in each sample were calculated at level of phylum, class, order, family, genus and species. QIIME was applied to obtain abundance of each species in samples, and distribution histogram at each taxonomic level were generated by certain R package. Alpha diversity metrics were evaluated by QIIME2. Beta diversity analysis was processed by QIIME. Blood was collected from the mice after they were fed for one month. The contents of estradiol and testosterone in serum of mice were determined by radioimmunoassay (RIA). [Results] Sex hormone levels in female and male mice decreased significantly after ovulation (Table 1). At phylum level, the intestinal bacterial communities of both normal mice and castrated mice were composed of Bacteroidetes, Firmicutes, Proteobacteria, Epsilonbacteraeota, Patescibacteria, Actinobacteria, Tenericutes, Deferribacteres, Acidobacteria and Cyanobacteria (Fig. 4). The populations of major bacteria found in normal and castrated mice were similar, with Firmicutes and Bacteroides as the dominant flora, and the sum of relative abundance percentages of the two flora was more than 80% (Table 4). Alpha diversity showed no significant difference in microflora evenness between the normal group and the castrated group (Table 5). Beta diversity showed no significant difference in microflora structure between the normal group and the castrated group. Followings are Beta diversity analysis based on four distance matrices: PCA analysis; PERMANOVA analysis and UPGMA analysis (Fig. 8). [Conclusion] The change of sex hormones did not cause the difference in the composition of the intestinal flora of mice.