被动游泳运动对小鼠抑郁样行为及其肠道菌群组成的影响

被动游泳运动可诱发小鼠抑郁样行为，游泳环境的改变已成为抑郁样行为严重程度影响因素之一。观察不同水质、水温及持续时间对被动游泳小鼠抑郁样行为的影响，并初步探讨肠道菌群组成与抑郁样行为的关系。通过不同条件下的被动游泳运动建立抑郁样行为小鼠模型。采用糖水偏好实验及强迫游泳实验评价其行为学变化；采用16S rDNA高通量测序技术及实时荧光定量PCR技术对小鼠肠道菌群进行分子生态学分析。被动游泳16周后，各模型组小鼠体质量及糖水偏爱度均较正常对照组降低，而不动时间则有所延长。其中，室温海水游泳15 min小鼠体质量及糖水偏爱度降低程度最大，不动时间最长，与正常对照组比较，均具有显著性差异（P<0.05）。各模型组小鼠肠道菌群Chao指数、Shannon指数及PCoA分析均较正常对照组具有显著性差异（P<0.05），其从门水平到属水平的丰度也发生不同程度改变。其中，室温海水游泳15 min小鼠肠道菌群组成变化程度最大，并发生拟杆菌属、普氏菌属等多个菌属的富集以及乳杆菌属丰度的减少，实时荧光定量PCR实验也得到了较为一致的结果（P<0.05）。以上结果表明，被动游泳运动可导致小鼠抑郁样行为的发生，其肠道菌群组成也发生明显改变；同时，菌群组成的改变会随着抑郁样行为的严重程度而有所变化。

Influence of Passive Swimming on Depression-Like Behavior and Intestinal Microbial Community Composition in Mice

Passive swimming can induce mice depression-like behavior, the change of swimming environment was also one of the factors influencing the severity of depression-like behaviors. In this study, the effects of different water quality, water temperature and duration on depression-like behavior were observed in passive swimming mice, and the relationship between intestinal microbial composition and depression-like behavior was also discussed. A depression-like model of mice was established by passive swimming under different conditions. The behavioral changes were evaluated adopting sugar water preference experiment and forced swimming experiment; and 16S rDNA high-throughput sequencing and real-time quantitative PCR were used to analyze the intestinal microbial population composition in mice. 16 weeks after the passive swimming, the body weight as well as sugar water preference degree of mice in each model group were lowered as compared with those in the normal control group, while the time of immobility was prolonged. Among them, the body weight and sugar water preference degree decreased the most in mice that swimming in seawater at room temperature for 15 min, and the duration of immobility of its was the longest as compared with control group, and all had significantly different (P<0.05). Analyses of Chao index, Shannon index as well as PCoA of intestinal microbial population in each mice of model group were significantly different (P<0.05) as compared with normal control group. And their abundance at phylum level and genus level developed changes at different degree. Among them the composition of intestinal microbial population showed the greatest change in mice swimming in seawater at room temperature for 15 min, and developed enrichment in multiple genera such as Bacteroides, Prevotella, as well as the decrement of the abundance of Lactobacillus; meanwhile, relatively consistent results were also obtained using real-time fluorescence quantitative PCR experiments (P<0.05). The above results showed that passive swimming could induce the depression-like behavior as well as significant changes of intestinal microbial population composition in mice, at the same time, the changes in intestinal microbial population composition also developed concomitant changes with the severity degree of depression-like behavior.