The Effect Of Aerobic And Resistance Exercise On Skeletal Muscle Musculature In Tail-suspended Rats

Objective: To study the effects of different exercise interventions(aerobic exercise,resistance exercise and aerobic + resistance exercise)on the recovery of atrophy of soleus muscles and gastrocnemius muscles and expression of muscle factors,and to explore the potential association between muscle atrophy and recovery and muscle factors.Methods: Fifty-six male 8-week-old rats were randomly divided into control group C(n=16)and suspension group T(n=40).C group was randomly divided into blank control group C1(n=8)and quiet control group C2(n=8).The tail suspension system(TSS)was used to perform a 2-week tail suspension experiment on the T group.After 2 weeks of tail suspension,the T group was randomly divided into T1(suspension group 1),CT(recovery group),A(aerobic exercise),R(resistance exercise),and AR(aerobic + resistance exercise)groups,8 in each group.A,AR,and R groups continued for 2 weeks of aerobic exercise,resistance exercise,and aerobic + resistance exercise training.Two weeks after the tail suspension test,the weights of the rats in the C1 and T1 groups and the wet weights of soleus and gastrocnemius muscles were measured.After 2weeks of exercise training,the weights of rats in C2,CT,A,AR,and R groups and the wet weights of soleus and gastrocnemius muscles were measured.HE staining was performed under light microscope to observe the changes of muscle fiber area of skeletal muscle in each group.Western-blot was used to detect the protein expression of MURF1,PGC-1? and FNDC5 in soleus muscle and gastrocnemius muscle of each group.Results:(1)The soleus muscle and gastrocnemius muscle mass in T1 group decreased by 28.6%(P<0.05)and 25.8%(P<0.01),respectively.After 2 weeks of exercise intervention,body weight and skeletal muscle wet weight returned to normal levels in all groups.(2)The cross-sectional area of soleus muscle and gastrocnemius muscle fiber in T1 group decreased by 20.5%(P<0.01)and 25.2%(P<0.05),respectively.After 2 weeks of exercise intervention,muscle fibers in the skeletal muscle group of the exercise group increased significantly(P<0.01),and resistance exercise had a significant improvement in the atrophy of the gastrocnemius muscle(P<0.05).(3)The MURF1 protein expression in the gastrocnemius muscle and soleus muscle in the T1 group was significantly higher than that in the C group(P<0.01).After 2 weeks of exercise intervention,MURF1 protein content in skeletal muscles of exercise group wassignificantly lower than that in recovery group(P<0.05),and MURF1 in skeletal muscle of exercise-resistant group was the most significant(P<0.01).(4)The expression of PGC-1? protein in gastrocnemius muscle and soleus muscle of T1 group was significantly lower than that in group C(P<0.05).After 2 weeks of exercise intervention,PGC-1? content in the gastrocnemius muscle and soleus muscle of the exercise group was higher than that in the group C(P<0.01).Compared with the CT group,the expression of PGC-1? protein in the exercise group was significantly increased(P<0.01).(5)The expression of FNDC5 protein in gastrocnemius muscle and soleus muscle in T1 group was significantly lower than that in group C(P<0.05).After exercise intervention for 2 weeks,the content of FNDC5 in skeletal muscle of exercise group was higher than that in group C(P<0.01).Compared with CT group,the expression of FNDC5 protein in skeletal muscle of exercise group increased significantly(P<0.01).The content of FNDC5/Irisin in soleus muscle of AR rats was significantly higher than that in group A(P<0.01).Conclusion:(1)After sole tail suspension for 2 weeks,the soleus muscle and gastrocnemius muscles of the rats were obviously atrophied,and soleus muscle atrophy was more obvious.Skeletal muscle atrophy may be related to increased expression of MURF1.(2)2 weeks of exercise training can significantly improve soleus muscle and gastrocnemius muscle atrophy.Compared with pure aerobic exercise,resistance exercise and aerobic + resistance exercise have a more significant effect on improving skeletal muscle atrophy.Exercise can improve skeletal muscle atrophy by regulating PGC-1? and FNDC5/Irisin.