Effects of Exhaustive Exercise on Autophagy and Relevant Regulatory Mechanisms in Murine Skeletal Muscle Cell

Objective:The effects of exhaustive exercise on autophagy in skeletal muscles of C57BL/6mice were studied to explore the role and mechanism of AMPK in autophagy regulation.Methods:96 eight-week C57BL6 mice were randomly divided into AICAR injection group,exhaustive exercise group,compound C injection+exhaustive exercise group and corresponding control groups.Mice were killed at 1h,2hand 6hrespectively after AICAR injection or sacrificed at immediately after exhaustive exercise,3h,6h,12hand 24hrespectively after running to exhaustion at a final speed of 11m/min.ELISA was used to analyze AMPK activity,Western blot analysis was used to test protein expression of p-ULK1,ATG7,LC3,Beclin1 and p62while the interaction of AMPK and ULK1was measured by co-immunoprecipitation.Results:Compared to SC group,AMPK activity,p-ULK1,the interaction between AMPK and ULK1,LC3-I,LC3-II as well as the ration of LC3-II/LC3-I increased markedly 1hafter AICAR injection while Beclin1,ATG7decreased significantly(P0.05)and p62remained unchanged.All return to normal after 2h besides LC3-II decreased continuously.For EE groups,AMPK activity,p-ULK1,AMPK/ULK1interaction,LC3-I,LC3-II and ratio of LC3II/LC3-I increased significantly immediately after exercise(P0.01)and decreased significantly at recovery period(3h,6h,12h,24h)(P0.05).Beclin1,ATG7and p62decreased significantly immediately after exercise while ATG7remained lower than SC group,Beclin1and p62gradually recovered.However,exhaustive exercise did not influence AMPK activity,pULK1and the interaction of AMPK/ULK1after Compound C injection.LC3-I,LC3-II and ratio of LC3-II/LC3-I changed similar to EE group but they are greatly lower than EE group(P0.05).Atg7,Beclin1changed similar to EE group,but they are still higher than EE(P 0.05).p62increased significantly immediately after exercise and dropped at recovery period(3h,6h,12h,24h)(P0.05).Conclusion:AMPK plays a great role in autophagy regulation in murine skeletal muscle.Exhaustive exercise significantly activates autophagy of skeletal muscle via AMPK/ULK1pathway,but AMPK is not the only pathway involved in this process.