Effects Of Calorie Restriction And Aerobics On Skeletal Muscle Mass And Regulation Of Autophagy In Obese Rats

Objective:Reducing energy intake or increasing energy expenditure can reduce fat.Calorie restriction and exercise are common methods in the above process,but the effects of both on skeletal muscle mass are not clear.Autophagy is a way to maintain skeletal muscle mass.Therefore,this study intends to limit the energy intake and exercise intervention in obese rats,observe the changes in body weight,fat mass and skeletal muscle,detect autophagy-related proteins in skeletal muscle of rats and explore the effects of calorie restriction and exercise on weight loss and skeletal muscle mass.Methods:Seventy healthy male Spraque Dawley?SD?rats of 5 weeks old were randomly divided into control group?C,n=10?and high fat diet group?H,n=60?.The control group was fed with normal diet,and the high-fat diet group was fed with high-fat diet.After 8 weeks,40 rats with body weight exceeding 20%of the control group were identified as obese rats.The control group fed with high-fat diet?HC,n=10?,the exercise group fed with high-fat diet?HE,n=10?,the calorie restrict control group?CRC,n=10?,and the calorie restrict exercise group?CRE,n=10?;70%of food calorie intake was used as calorie restrict.Exercise intensity is 60%-70%VO₂max in treadmill for 60min for 6 days a week.After 4 weeks of intervention,the body weight of the rats was weighed,and the fat mass of the rats was determined by dual energy X-ray absorptiometry?DEXA?.The rats were sacrificed and the wet weight of soleus muscle was weighed.Frozen sections Immunofluorescence was used to detect Laminin and observe the cross-sectional area of soleus fiber.Western Blot was used to detect the expression of autophagy-related proteins LC3,p62,AMPK?,p-AMPK?and ULK1 in soleus,and LC3 was determined by immunofluorescence technique to investigate signal regulation.Using Spss19.0 two-way ANOVA was used to analyze the variance.The data were expressed as mean±standard deviation?x±s?,and p<0.05 was considered statistically significant.Result:1)The results showed that after 4 weeks of intervention,the body weight and the fat mass of rats in HE,CRC and CRE groups decreased,and were significantly lower than the HC group?p<0.01?,which indicated that calorie restriction and aerobics can reduce weight.2)Compared with HC,the wet weight and the cross-sectional area of soleus of rats in CRC,HE and CRE had no obvious difference,which indicated that calorie restriction and aerobics will not reduce soleus mass;3)After 4 weeks of intervention,compared with HC group,the expression of LC3-II and LC3-II/LC3-I,AMPK?,p-AMPK??Thr172?,ULK1 in the soleus of rats in HE,CRC and CRE groups was higher?p<0.05?,the expression levels of p62 in the three groups were lower?p<0.05?,which indicated that calorie restriction can increase the level of autophagy in soleus.Conclusion:Calorie restriction and aerobics can effectively reduce the body weight and fat mass of obese rats,and has no significant bad effects on the mass of skeletal muscle.Calorie restriction and exercise can appropriately activate autophagy in skeletal muscle to maintain its morphology and function.