Keywords :
Animals; Cytokines/metabolism; Female; Mice, Inbred C57BL; Microfilament Proteins/metabolism; Muscle, Skeletal/drug effects/metabolism; Physical Conditioning, Animal; Physical Endurance/physiology; RNA, Messenger/metabolism; Signal Transduction; TOR Serine-Threonine Kinases/metabolism; Tumor Necrosis Factor-alpha/administration & dosage
Abstract :
[en] PURPOSE: To determine whether endurance training attenuates the negative effects induced by an acute injection of tumor necrosis factor-alpha (TNF-alpha) in skeletal muscle of mice. METHODS: Trained (6 wk of endurance training at 60% of maximal velocity) and untrained mice were injected with TNF-alpha or vehicle and killed 6 h after. Tibialis anterior muscles were analyzed using Western blot and qRT-PCR for markers of inflammation and protein synthesis/degradation. RESULTS: Independently of training, TNF-alpha increased the mRNA of cytokines and downregulated signals linked to protein synthesis. The phosphorylation of IKKalpha/beta and IkappaBalpha induced by TNF-alpha was blunted in trained mice, suggesting altered NF-kappaB activation. This was associated with lower induction of several markers of protein degradation (FoxO1, MURF1, MAFbx, myostatin, Gabarapl1, and LC3BII/LC3BI ratio). CONCLUSIONS: Endurance training protects skeletal muscle against the activation of protein degradation signaling pathways induced by TNF-alpha.
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