Resistance Exercise Induces Autophagy Through Irisin To Alleviate Amyotrophy In Type Ⅱ Diabetes

Background:Diabetic muscular atrophy is one of the common complications of diabetes,which seriously affects the quality of life of diabetic patients.With the change of life style and work mode,the trend of younger diabetes patients.Currently,there are few drugs for the treatment of diabetic muscular dystrophy,and exercise intervention is considered to be an important way to relieve muscular dystrophy by activating autophagy.However,the molecular regulatory mechanism of exercise-activated autophagy to improve muscular dystrophy in type2 diabetes is still lacking in-depth research.Irisin is a muscle factor secreted by exerciseinduced skeletal muscle,which has a protective effect on diabetic metabolism.However,the regulatory role of Irisin in muscular atrophy remains unclear.Therefore,whether exerciseinduced Irisin can improve diabetic muscular atrophy by activating autophagy needs further study,which will be beneficial to clarify the role of Irisin as an exercise simulator in diabetic muscular atrophy and provide theoretical basis for the prevention or treatment of diabetic muscular atrophy.Objective: To investigate whether resistive exercise-induced Irisin can improve muscular atrophy in type II diabetes by activating autophagy.Methods: Thirty-one SD rats were adaptive fed for 2 weeks,and 6 SD rats were treated as normal control group（NC group）,and fed basic diet for 16 weeks.Twenty-five SD rats were fed high-fat diet for 8 weeks and injected STZ for 2 weeks to build type II diabetes model.After successful modeling,they were randomly divided into diabetic quiet group（TN group）（n=6）,diabetic Irisin injection group（TI group）（n=6）,diabetic resistance exercise group（TE group）（n=6）.Fasting blood glucose was measured once a week from the beginning of the intervention.After the intervention,the experimental animals were weighed and sacrificed,and then the gastrocnemius muscle was collected,weighed and stained with HE.Western Blot assay was used to detect the expression of PGC-1α,FNDC5/Irisin,Atg7,Beclin1,P62,LC3-II/LC3-I,atrogin-1,Bax,Bcl-2,PINK1 and Parkin in gastrocnemius.Results: 1.Resistance exercise and Irisin injection can reduce blood glucose in T2 DM rats.After modeling,compared with NC group,fasting blood glucose in TN group,TI group and TE group increased significantly and remained stable,indicating that modeling was successful.Compared with NC group,fasting blood glucose in TN group increased significantly（p <0.001）;After 6 weeks of intervention,compared with the TN group,the FASTING blood glucose in the TI group decreased to some extent,but there was no significant difference,while the fasting blood glucose in the TE group decreased significantly（p <0.01）;TI group was significantly different from TE group（p <0.05）.2.Muscle atrophy rate: Compared with NC group,the wet weight ratio of gastrocnemius muscle in TN group was significantly lower（p <0.05）;In contrast,after exercise and Irisin intervention,the wet weight ratio of the gastrocnemius muscle in the TI and TE groups increased significantly compared with the TN group（p <0.01）;3.Histomorphology: Both resistance exercise and Irisin injection can improve muscle fiber structure of T2 DM rats.HE staining results showed that compared with NC group,the cross sectional area of gastrocnemius muscle fiber in TN group was significantly reduced（p<0.05）,increased connective tissue,disordered arrangement of muscle fibers,and obviously inward migration of nuclei.After 6 weeks of intervention,the cross-sectional area of gastrocnemius muscle fiber was higher in TE and TI groups than in TN group（p <0.05）,the connective tissue decreased,the muscle fibers arranged neatly,and the nuclear migration decreased or even disappeared.4.Western Blot experiment results:1)Muscle degrading protein: Both resistance exercise and Irisin injection reduced the expression of muscular atrophy marker protein in T2 DM rats.Compared with NC group,Atrogin-1 expression was increased in TN group（p <0.05）.After 6 weeks of resistance exercise and Irisin injection,Atrogin-1 protein was significantly reduced in TI group compared with TN group（p <0.01）,Atrogin-1 protein expression was decreased in TE group（p <0.05）.2)Irisin related proteins:Both resistance exercise and Irisin injection could improve the expression of Irisin protein.Compared with TN group,the expression of PGC-1α in TI group was significantly increased（p <0.0001）,Irisin increased significantly（p <0.05）;Compared with TN group,the expression of PGC-1α in TE group was significantly increased（p <0.001）,Irisin expression was significantly increased（p <0.05）.3)Autophagy related proteins: Compared with NC group,Atg7 protein in gastrocnemius of rats in TN group was significantly decreased（p <0.001）,Beclin1 protein expression was significantly decreased（p <0.01）,p62 protein increased significantly（p <0.01）,LC3-II protein increased significantly（p <0.05）.After 6 weeks of resistance exercise and Irisin injection,Beclin1 protein expression was significantly increased in the TI group compared with the TN group（p <0.001）,p62 protein significantly decreased（p <0.05）,LC3-II protein increased significantly（p <0.05）;Compared with TN group,Beclin1 protein expression in TE group was significantly increased（p <0.001）,p62 protein decreased significantly（p <0.05）,LC3-II protein expression was significantly increased（p <0.001）.Compared with NC group,PINK1 protein in gastrocnemius of rats in TN group was significantly decreased（p <0.05）;Compared with TN group,PINK1 and Parkin in gastrocnemius muscle fibers in TI group were significantly increased（p <0.05;p<0.05）,the expression of PINK1 and Parkin increased in TE gastrocnemius to varying degrees（p <0.001;p <0.05）.4)Apoptosis-related proteins: Compared with NC group,the expression of skeletal muscle apoptosis protein Bax was significantly increased in TN group（p <0.01）,Bcl-2 decreased;Compared with TN group,the expression of Bax in skeletal muscle of TI group and TE group was significantly decreased（p <0.05;p <0.01）,but the expression of Bcl-2 in skeletal muscle was significantly increased in TI and TE groups（p <0.05;p <0.01）Conclusion: Resistance exercise and Irisin injection can effectively relieve or improve skeletal muscle atrophy in T2 DM rats,and the main mechanism may be related to increasing the expression of Irisin in skeletal muscle to activate autophagy and inhibit apoptosis.