Mechanism Of Salidroside On Mouse Skeletal Muscle Fiber Type And Endurance

Objective:The study is aim to discuss the effect of Rhodiola(RHO)and Salidroside(SAL)supplement on exercise endurance,from the angle of the morphological changes and fiber type transformation in skeletal muscle.On the basis of detection of AMPK/PGC-la,TGF-?/Smad3,autophagy and other factors,trying to find the mechanism of promotion fiber type transformation and regulation exercise endurance.We want to Lay the foundation for further study,and provide the basis for the application of SAL.Methods:Experiment one.All the C57BL/6 mice were run at a speed of 15 m/min in a horizontal treadmill until exhaustion.Detect the expression of PGC-la,p62,LC3-?,LC3-? protein by western blot after execute.Experiment two.The C57BL/6 mice pre and post four weeks oral RHO and SAL were measured endurance and weight under the exercise model of experiment one,and measured the muscle wet weight after execute.Experiment three.The C57BL/6 mice were divided into no exercise and saline group(PS-,Con-),exercise and saline group(PS+,Con+),no exercise and SAL group(Sal-),exercise and SAL group(Sal+).After execute under tonic model,detect the nimber of muscle fibers and cross-sectional area by immunofluorescent,detect the gene expression of MHC and autophagy by Real-time quantitative PCR,detect the expression of TnI SS,TnI FS,AMPKa,p-AMPKa,Smad3,p-Smad3 protein besides involved in experiment one.Results:(1)In exhaustive exercise,PGC-la protein expression in slow-twitch muscle fibers was significantly higher than in fast-twitch muscle fibers,LC3-I and LC3-II protein expression in exha,ustion was significantly higher than the control.(2)After four weeks,the endurance of oral SAL were significantly higher than control,endurance increased 75%compared with pre experiment.Little change in body weight and lower extremities wet muscle weight of mice.(3)Detection gastrocnemius found that cross-sectional area of oral SAL were significantly higher than control,the number of fibers may be increased.The cross-sectional area and gene expression of type I fiber of SAL gastric lavage were significantly higher than control,the cross-sectional area and gene expression of type ?b fiber of SAL gastric lavage were significantly lower than control.The slow-twitch muscle fiber protein expression of Sal+ was significantly higher than the PS+,the fast-twitch muscle fiber protein expression of Sal+ was significantly lower than the PS+.(4)AMPK?,p-AMPK? and PGC-1? protein expression of Sal+ were significantly lower than PS-.Smad3 protein expression of Sal-was significantly lower than PS-,p-Smad3 protein expression of Sal+was significantly lower than the PS-and PS+.p62,LC3-?,LC3-? protein expression of Sal+ was significantly higher than the PS+,LC3-?,LC3-?protein expression of Sal-was significantly higher than the PS-,however p62 of Sal-has been dropped,but no significant difference.Conclusion:RHO and SAL gastric lavage four weeks could improve endurance,but the endurance of SAL gastric lavage is better.SAL has little effect on body weight and muscle weight,it can enhance the MHC-I and TnI SS,and inhibit the MHC-?b and TnI FS.So SAL can promote skeletal muscle fiber transformation as type ?b?type ?d/x?type ?a?type ?,enhance endurance and against disuse muscle atrophy.Although p-AMPKa and PGC-1 a selective high expression in the slow-twitch muscle fibers to verify the role of muscle fiber type transformation,four weeks SAL gastric lavage inhibit this pathway in our experiment under the model.Although inhibition TGF-?/Smad3 SAL can promote transformation,it can not determine a mechanism to enhance the endurance.The SAL activate the autophagy pathway to promote exercise ability,and it may be the mechanism of enhance endurance.