Gut Microbiota Removal Eliminates Enhanced Exercise Capacity Mediated By Skeletal Muscle Metabolome And Mitochondrial Proteins

The Regulator of G Protein Signaling 14 knockout (RGS14 KO) mouse is a model for healthful aging and has unique brown adipose tissue and skeletal muscle (SKM) mechanisms mediating its phenotype of improved exercise performance i.e., a 51 ± 8% increase in running distance (meters/min) compared to wild type (WT) mice. Additionally, eliminating the RGS14 KO microbiota with antibiotic treatment (ABX) abolished the enhanced exercise capacity (EXC) in the RGS14 KO mice. PURPOSE: The goal of this investigation was to determine if the distinct gut microbiota and SKM metabolism in the RGS14 KO mice mediate its enhanced EXC. We examined 1) EXC, 2) tissue (quadriceps) metabolome, and 3) SKM content of markers linked to exercise performance in RGS14 KO mice before and after ABX. METHODS: Thirty-eight male mice (n = 14 RGS14 KO, n = 10 WT, n = 8 RGS14 KO + ABX, n = 6 WT + ABX) were used to examine EXC, identify predominant metabolites in SKM and analyze the expression/content of proteins linked to EXC, e.g., nitrate/nitrite (NO), citrate synthase (CS), complex IV, AMP-activated protein kinase (AMPK), and sirtuin-3 (SIRT3) before and after ABX. Statistical analysis included Student’s T-test for two groups and ANOVA for multiple group comparisons. RESULTS: ABX eliminated the enhanced EXC in RGS14 KO mice. Significant baseline SKM metabolite pathways included purine (p < 0.001) and phenylalanine (p < 0.01) metabolism, branched-chain amino acid metabolism (p < 0.01) and the pentose phosphate pathway (p < 0.05). No significant SKM metabolite pathways were detected after ABX. Mitochondrial protein analysis revealed that RGS14 KO mice had significantly higher NO, CS, AMPK and SIRT3 (77%, 77%, 20% and 265%, respectively) relative to WT mice before ABX. After ABX, RGS14 KO mice showed more significant protein decreases than WT mice, eliminating the previously observed higher levels. CONCLUSIONS: Our findings demonstrate that the resident microbiota positively influences RGS14 KO SKM and its associated EXC; after ABX, the enhanced EXC in RGS14 KO mice compared to WT is eliminated. These findings support the multi-axis communication of the gut microbiota with host muscle and EXC via metabolites and mitochondrial protein content. This research also demonstrates that alterations to the gut microbiota can affect exercise performance. ONR Grant #826640