Effects Of Aerobic Exercise On ADRβ3-COX2-UCP1 Xpression Levels In HFD Rat Adipose Tissue

Objective:This study was designed to observe aerobic exercise regulating ADRβ3-COX2-UCP1 in adipose tissue and explore its possible mechanism to regulate lipolysis of brown adipose tissue.Methods:1)Seven-weeks-old male SD rats were divided into control group（N,n=14）and high-fat diet group（H,n=14,fed with high-fat chow）randomly.After 10 weeks feeding,group N and H were randomly divided into control groups（NC and HC）and exercise groups（NE and HE）evenly.NE and HE were applied with aerobic exercise（treadmill）for 8 weeks.After intervention,the differences between body composition of each groups were compared;perirenal and epididymal white adipose tissue（WAT）,and interscapular brown adipose tissue（BAT）were carefully dissected and weighted;the rats’serum were collected for total cholesterol（CHO）and triglyceride（TG）analysis;protein expression levels of Uncoupling Protein 1（UCP1）,Cyclooxygenase 2（COX2）,Adrenergic receptorβ3（ADRβ3）,and Vascular Endothelial Growth Factor a（VEGFa）in perirenal WAT and BAT were analyzed by immunoblots;mRNA expression level of Ucp1,Vegfa,and Cox2 in BAT were analyzed by Real-Time PCR.2)Brown adipocytes（BAC）were differentiated from C₃H₁₀T_1/2/2 cells.Differentiated BAC were treated with ADRβ3 agonist Isoprenaline and/or COX2 inhibitor NS-398 for 6h.Then,BACs were fixed for Oil Red O staining and the medium were collected for adipolysis analysis.Results:1)Aerobic exercise prevented body mass increase induced by high-fat diet（HFD）.Aerobic exercise also reduced Lee’s index,fat mass,and WAT mass.The BAT%in NE increased significantly.There were no significant TG changes between groups,but CHO levels in HE reduced significantly.2)In BAT,protein expression levels of UCP1,COX2 and ADRβ3 increased significantly in animals fed normal chow after exercise intervention,which also increased in HE without statistical significance.The mRNA level of Cox2 boosted after exercise.HFD increased the Vegfa mRNA level.3)In perirenal WAT,VEGFa,COX2 and UCP1expression increased significantly after exercise.4)The red color after Oil Red Staining became lighter and the size of the lipid droplets turned smaller with ISO treatment,which inhibited by NS-398.5)NS-398 inhibited the BAC adipolysis induced by Isoprenaline.Conclusion:exercise can up-regulate UCP1 expression in BAT and perirenal WAT by increasing COX2 activity in adipose tissue.The increased COX2 shifted the UCP1 expression and de novo BAT recruitment in WAT which may increase systemic energy expenditure,reducing body weight and body fat content,and improving the body’s resistance to HFD.The COX2 plays an important role in this regulation process and can be used as a new target in the study of activating brown fat,increasing browning of fat tissue and reducing fat.