Effects Of 4-week Exercise And Calorie Restriction On Fat-reducing And The Change Of Irisin In Obese Rats

Objective: Exercise and diet therapy are the useful ways to lose weight.Irisin is myokines,and fibronectin type III domain containing protein 5(FNDC5)is irisin's precursor protein in skeletal muscle.Its main function is to induce white adipose tissue browning and increase the body's energy consumption,achieve the purpose of lossing weight.In recent years,Irisin has received extensive attention for energy metabolism.In this study,obesity rats were obtained through calorie restriction,exercise.To compare the effects of calorie restriction and exercise to FNDC5 protein expression,white fat browning on skeletal muscle of obese rats and the effect of reducing fat,provide reference value for the relationship between calorie restriction and Irisin.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 rats were fed with high-fat diet.After 8 weeks,obese rats were randomly divided into high-fat diet control group(HC group),high-fat diet+exercise group(HE group),calorie restriction control group(CRC group),calorie restriction+exercise group(CRE group),10 of each group.The high-fat diet group continued to feed high-fat diet during the intervention period,and the calorie restriction group fed 70% of the daily feed volume in the high-fat diet group.Exercise intensity is 60% VO2 max in treadmill with the speed of 15m/min for 60 min for 6 days a week.After 4 weeks,Rat body weight was recorded weekly,Dual-Energy X-Ray Absorption(DEXA)was used to analyze the body fat mass,then separate bilateral soleus and record the wet weight,measure the cross-sectional area of the soleus fibers by testing laminin with immunofluorescence confocal,determination of Irisin in serum by ELISA.The expression of protein PGC-1?,AMPK?,p-AMPK?(Thr172),FNDC5,it indicates that Irisin in serum can promote the expression of FNDC5 in skeletal muscle through AMPK?-PGC-1?pathway.The expression of p38 MAPK and UCP1 protein in the perirenal white fat of HE group and CRE group was significantly higher than that of HC group(p<0.05),indicating that exercise and energy intake restriction intervention can promote UCP1 expression and increase body energy consumption.p<0.05 was considered statistically significant.Results:(1)After 4 weeks of intervention,the body weight and body fat content of HE group,CRC group and CRE group were significantly lower than those of HC group(p<0.01),the lowest in HE group,the second in CRC group and the highest in CRE group.(2)Compared with group HC,the soleus muscle wet weight was no significant difference(p> 0.05).(3)The wet weight of white fat and the wet weight of brown fat of HE group,CRC group and CRE group were significantly lower than HC group(p<0.01).(4)The levels of serum Irisin in HE group and CRE group were higher than HC group(p<0.05).(5)The expression levels of PGC-1?,AMPK?,p-AMPK?(Thr172)and FNDC5 protein in soleus muscle of HE group and CRE group were significantly higher than HC group(p<0.05).The expression levels of p38 MAPK and UCP1 protein in white fat of HE group and CRE group were significantly higher than those in HC group(p<0.05).Conclusion: Calorie restriction can significantly reduce the body weight and body fat content of obese rats,and has an effect similar to exercise.It has no obvious effect on skeletal muscle,the combination of the two was better.Calorie restriction and exercise can significantly increase the level of FNDC5 and serum Irisin in rat skeletal muscle,and promote the expression of FNDC5 in skeletal muscle through AMPK?-PGC-1? pathway,promoting white adipose tissue browning by increasing UCP1 expression in adipose tissue.Calorie restriction can be used as a convenient and effective way to loss weight in a particular population.