The Role Of AMPK In The Regulation Of Autophagy By Exercise In Skeletal Muscle Of Aged Mice

Objectives:An aerobic exercise training model was established to observe the effect of aerobic exercise on skeletal muscle autophagy in aged mice;Combine exercise with the application of Adenosine 5'-monophosphate(AMP)-activated protein kinase(AMPK)inhibitor Compound C to explore the role of AMPK in modulating skeletal muscle autophagy by aerobic exercise in aged mice.Methods:Eighteen healthy 16-month-old female ICR mice were randomly divided into three groups after one week of adaptive feeding:old control group(OC),old exercise group(OE)and old exercise combined AMPK inhibitor Compound C(OE+C)group.The OC group did not receive any exercise intervention.The OE and OE+C groups were given 4 weeks of aerobic exercise training.In the OE+C group,AMPK inhibitor Compound C was intraperitoneally injected at a dose of 10 mg/Kg every 4 days.24 hours after last exercise,grip strength test and balance beam test were conducted.Western blot method was used to detect autophagy-related proteins expression(including LC3,p62,Beclinl,Atg7,Parkin)and autophagy-modulating factor AMPK,mTOR phosphorylation levels in mice's gastrocnemius.Results:1.Comparison of the grip strength and balance function of old mice in different groups.The grip strength test results showed,compared with the OC group,there was no significant difference in the grip strength score of the OE group(P>0.05);Compared with the OE group,the grip strength score was not significantly different in the OE+C group(P>0.05).The results of the balance function test revealed,compared with the OC group,the beam-walking time of mice in the OE group significantly decreased(P<0.05);Compared with the OE group,the beam-walking time was not significantly different in the OE+C group(P>0.05).2.Comparison of the expression of autophagy-related proteins in skeletal muscle of aged mice.Compared with the OC.group,LC3Ⅱ/LC3Ⅰ ratio and LC3Ⅱ expression in gastrocnemius of the OE group significantly increased(P<0.05,P<0.05);Compared with the OE group,LC3 Ⅱ/LC3 Ⅰ ratio and LC3Ⅱ expression in gastrocnemius of the OE+C group decreased significantly(P<0.05,P<0.05).Compared with the OC group,there was no significant difference in p62 expression in gastrocnemius of the OE group(P>0.05);Compared with the OE group,there was no significant difference in p62 expression in gastrocnemius of the OE+C group(P>0.05).Compared with the OC group,the expression of Beclinl significantly increased in gastrocnemius of the OE group(P<0.05);Compared with the OE group,Beclinl expression decreased significantly in gastrocnemius of the OE+C group(P<0.05).Compared with the OC group,the expression of Atg7 significantly increased in gastrocnemius of the OE group(P<0.05);Compared with the OE group,Atg7 expression decreased significantly in gastrocnemius of the OE+C group(P<0.05).Compared with the OC group,the expression of Parkin significantly increased in gastrocnemius of the OE group(P<0.05);Compared with the OE group,Parkin expression decreased significantly in gastrocnemius of the OE+C group(P<0.05).3.Comparison of the phosphorylation of autophagy-modulating factor AMPK,mTOR in skeletal muscle of aged mice.Compared with the OC group,the p-AMPK/AMPK ratio in gastrocnemius of the OE group increased significantly(P<0.05),while the p-mTOR/mTOR ratio decreased significantly(P<0.05);Compared with the OE group,the p-AMPK/AMPK ratio decreased significantly in gastrocnemius of the OE+C group(P<0.05),while the p-mTOR/mTOR ratio increased significantly(P<0.05).Conclusions:1.Aerobic exercise training activated the autophagy in skeletal muscle of aged mice.2.Compound C(an AMPK inhibitor)canceled the effect of aerobic exercise on autophagy activation,suggesting that AMPK played a role in aerobic exercise modulating autophagy in aging skeletal.