Effects Of Alternate Day Modified Fasting Combined Exercise On Fat Reducing And The Regulation Of PGC-1α-FNDC5/Irisin Pathway

Objective: Alternate-day fasting(ADF)has the effect of promoting thermogenesis of fat and browning of white fat,but the situation of long fasting and low energy intake will make it difficult to guarantee skeletal muscle quality.This study investigated the effects of alternate-day modified fasting(ADMF)alone and combined exercise interventions on fat and skeletal muscle in rats using ADMF and moderate-intensity exercise as interventions,and to investigate the changes of energy metabolism and the role of PGC-1α-FNDC5/Irisin-UCP1 pathway in browning of white fat and maintaining skeletal muscle mass,and reveal the regulatory mechanism of ADMF fat reduction and ADMF combined exercise.To provide a theoretical basis for exploring more effective fat loss methods.Methods: 40 male Sprague Dawley(SD)rats of 8-week-old were divided into control group(Con),exercise group(Exer),alternate-day modified fasting(ADMF),alternate-day modified fasting combined exercise group(ADMF-Exer),10 rats / group.After 4 weeks of aerobic exercise and ADMF,food intake,weight and body length were recorded on time.Statistics and calculation of changes in rat body weight and body fat after 4 weeks;gastrocnemius muscles were isolated at the time of material extraction,Laminin protein was detected by immunofluorescence to measure the cross-sectional area of muscle fibers,and Western Blot was used to detect PGC-1α,AMPKα,pAMPKα(Thr172),FNDC5 protein expression;Level of Irisin of rat serum was detected by ELISA;Separate rat perinephric fat,epididymal fat and brown fat to weigh wet weight.HE staining was used to observe the changes in fat morphology and quantity,and the expression of UCP1 protein in fat was detected by Western Blot.All experimental data were expressed as mean ± standard error((?)± SEM).Two-way analysis of variance was performed using SPSS 22.0 software.Results:(1)The energy intake of ADMF group and ADMF-Exer group was significantly lower than that of Con group and Exer group(P<0.01).(2)In terms of weight and body fat after 4-week intervention,the Exer group,ADMF group,and ADMF-Exer group were significantly lower than the Con group(P<0.05),and the ADMF-Exer group was significantly lower than the Exer group(P<0.05).(3)The gastrocnemius muscle weight of ADMF group was significantly lower than that of Con group(P<0.05),but there was no difference in other groups.The cross-sectional area of the gastrocnemius muscle in the Exer group and the ADMF-Exer group was significantly higher than that in the Con group(P<0.01).(4)Compared with the Con group,the white fat mass of the Exer group,the ADMF group,and the ADMF-Exer group was significantly reduced(P < 0.01).Although the fat mass of the scapula increased,there was no statistical difference.There was no statistical difference in the size of epididymal adipocytes after exercise and fasting interventions,but the changes in perinephric adipocytes were significant.Compared with the Con group,the size of the adrenal adipocytes in the Exer,ADMF,and ADMF-Exer groups was significantly smaller(P<0.01).(5)p-AMPKα(Thr172)/ AMPKα,PGC-1α,FNDC5 and serum Irisin were increased in Exer group,ADMF group and ADMF-Exer group compared with Con group(P<0.05).p-AMPKα(Thr172)/ AMPKα,PGC-1α,FNDC5 and serum Irisin were increased in ADMF-Exer group compared with Exer group(P<0.05)(6)Compared with the Con group,UCP1 was significantly increased in the epididymal fat and scapular fat of the Exer,ADMF,and ADMF-Exer groups(P<0.01).Compared with the Exer group,UCP1 was significantly increased in the epididymal fat and scapular fat of the ADMF-Exer groups(P<0.01).Conclusion:(1)ADMF combined exercise can effectively reduce fat and control body weight,its effect is better than pure ADMF or exercise.(2)Energy metabolism changes PGC-1α-FNDC5 / Irisin is activated by AMPK to up-regulate UCP1 expression in fat to regulate the energy metabolism of white fat and brown fat.(3)ADMF will not cause the loss of skeletal muscle mass in normal-weight rats.It is recommended to combine aerobic exercise in the process of ADMF to achieve a better fat-reducing effect.