Effects of voluntary exercise on plasma and urinary metabolites and gut microbiota in mice fed with high-fat-diet

The aim of this study was to examine the effects of voluntary exercise on plasma and urinary metabolites and the changes in gut microbiota in mice fed with a high-fat-diet. Healthy male C57BL/6J mice (four-week-old, n = 27) were fed a normal controlled diet (CD) and a high-fat-diet (HFD) for 10 weeks under two conditions: voluntary wheel running (W) and sedentary controlled condition (C). The metabolites in the collected plasma and urine were detected using 1 H-NMR spectroscopy techniques. Also, 16S-rRNA gene next-generation sequencing was carried out on the collected feces. Wheel running activity in HFDW mice was slightly higher than that in CDW mice (p = 0.075). Exercise and diet significantly altered body weight, fat accumulation, and glucose tolerance tests. In plasma, amino acids such as Leu, Ile, Ala and Tyr, were increased by exercise. Diet influenced the metabolites in both the plasma and urine of mice and showed significant differences; in plasma, Leu, Ile, Glu, 3-HB, lactate and acetate, whereas in urine, citrate, trimethylamine (TMA), trimethylamine-N-oxide (TMAO), taurine, hippurate and allantoin. With regard to beta diversity, unweighted UniFrac analysis (principal coordinate analysis: PCoA) showed the difference between CD and HFD mice could be observed under PC1 (22.61%). Although there was substantial overlap between two conditions (C vs. W), HFD groups were positioned in a slightly different area when compared to the C and W conditions. Firmicutes/Bacteroidetes ratio, which might be associated with obesity, in HFD mice was significantly higher than that in CD mice, but not affected by wheel running. Our results suggest that testing in both plasma and urinary metabolites may prove to be a more reliable approach to quantitative metabolite analysis on the effects of exercise-dependent hosts or as an independent alteration of gut microbiota on the hosts.