Time Course of Mitophagy‐Related Signals in Skeletal Muscle Following a Single Bout of Aerobic Exercise in Mice

Abstract

This study aimed to investigate mitophagy‐related signals in skeletal muscle following a single bout of aerobic exercise in mice. C57BL6 mice were submitted to a single bout of treadmill aerobic exercise for 80 minutes at 60% of maximal speed achieved in a graded treadmill test. Skeletal muscles were harvested at rest, immediately after the bout of aerobic exercise and after 3, 6, 12 and 24h of recovery. One hindlimb was used for fresh isolation of skeletal muscle mitochondrial‐enriched fraction (MF), and contralateral muscles were immediately frozen. Immunoblotting for LC3, p62 and Bnip3 were performed either in quadriceps muscles or MF. qPCR were performed to evaluate mRNA levels of LC3, p62 and Bnip3 in quadriceps muscles. No protein was differentially expressed in total lysate of quadriceps muscle. However, LC3‐II levels were significantly increased in MF immediately after the bout of aerobic exercise (72.5%) and after 12h of recovery (63.3%), whereas p62 protein levels were increased at 6 (30%) and 12h (62.5%) of recovery. Bnip3 protein levels displayed a trend toward to increase (p=0.06) after 3h of recovery (36.4%). No difference was found in mRNA levels of LC3, p62 and Bnip3 at any time point. Collectively, these results suggest that mitophagy signaling is increased during aerobic exercise and decreases after its cessation. Interestingly, the retake of mitophagy signaling after 12h of recovery suggests that mitophagy plays an important role in skeletal muscle mitochondrial remodeling to acute aerobic exercise stimulus, independently of transcriptional regulation. Thus, these results provide new insights into aerobic exercise‐induced mitophagy and mitochondrial remodeling.Financial support: FAPESP 2013/21065‐3