| Autor: |
Dungan CM; Department of Rehabilitation Sciences, University of Kentucky , Lexington, Kentucky.; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Murach KA; Department of Rehabilitation Sciences, University of Kentucky , Lexington, Kentucky.; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Frick KK; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Jones SR; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Crow SE; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Englund DA; Department of Rehabilitation Sciences, University of Kentucky , Lexington, Kentucky.; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Vechetti IJ Jr; Department of Physiology, University of Kentucky , Lexington, Kentucky.; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Figueiredo VC; Department of Rehabilitation Sciences, University of Kentucky , Lexington, Kentucky.; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Levitan BM; Center for Molecular Medicine, University of Kentucky , Lexington, Kentucky., Satin J; Department of Physiology, University of Kentucky , Lexington, Kentucky., McCarthy JJ; Department of Physiology, University of Kentucky , Lexington, Kentucky.; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky., Peterson CA; Department of Rehabilitation Sciences, University of Kentucky , Lexington, Kentucky.; Center for Muscle Biology, University of Kentucky , Lexington, Kentucky. |
| Abstrakt: |
Myonuclei gained during exercise-induced skeletal muscle hypertrophy may be long-lasting and could facilitate future muscle adaptability after deconditioning, a concept colloquially termed "muscle memory." The evidence for this is limited, mostly due to the lack of a murine exercise-training paradigm that is nonsurgical and reversible. To address this limitation, we developed a novel progressive weighted-wheel-running (PoWeR) model of murine exercise training to test whether myonuclei gained during exercise persist after detraining. We hypothesized that myonuclei acquired during training-induced hypertrophy would remain following loss of muscle mass with detraining. Singly housed female C57BL/6J mice performed 8 wk of PoWeR, while another group performed 8 wk of PoWeR followed by 12 wk of detraining. Age-matched sedentary cage-dwelling mice served as untrained controls. Eight weeks of PoWeR yielded significant plantaris muscle fiber hypertrophy, a shift to a more oxidative phenotype, and greater myonuclear density than untrained mice. After 12 wk of detraining, the plantaris muscle returned to an untrained phenotype with fewer myonuclei. A finding of fewer myonuclei simultaneously with plantaris deconditioning argues against a muscle memory mechanism mediated by elevated myonuclear density in primarily fast-twitch muscle. PoWeR is a novel, practical, and easy-to-deploy approach for eliciting robust hypertrophy in mice, and our findings can inform future research on the mechanisms underlying skeletal muscle adaptive potential and muscle memory. |
