The Effect Of Phlorizin On Brown Adipose Tissue And Obesity Based On Tyk2/STAT3 Signaling Pathway

More and more studies show that promoting brown adipose tissue to burn the excess energy can effectively inhibit obesity.And Tyk2/STAT3 signaling pathway and can regulate differentiation and function of brown fat cells.Our previous study also found that phlorizin has a certain influence on obesity and Tyk2/STAT3 signaling pathway.So combination of the above,the hypothesis is proposed:phloridzin can inhibit obesity by adjusting Tyk2/STAT3 signaling pathway activity,and promoting brown fat cell differentiation and energy metabolism.ObjectiveThis study aims to explore the mechanism that Phlorizin inhibits obesity through Tyk2/STAT3 signaling pathway.The effects of Phlorizin on Tyk2 siRNA interference mice and nutrition obesity mice were observed.The activity of Tyk2/STAT3 signaling pathway and differentiation and energy metabolism of brown fat cell mediated by Tyk2/STAT3 signaling pathway were all studied.The scientific hypothesis of this study is that:Phlorizin inhibits obesity by regulating Tyk2/STAT3 signaling pathway activity,and promote brown adipocyte differentiation and energy metabolism.Methods一、Animal experimentTen C57BL/6J male mice of 4 weeks old were randomLy picked out as the normal group fed with normal diet,and the rest were fed with high-fat diet to establish nutrition obesity mouse model.The obesity mice were divided into model group,simvastatin group and phlorizin group.During administration,the body weight of mice were measured weekly and the temperature of mice were measured biweekly with thermal infrared imager.At the end of administration,the oral glucose tolerance test and insulin tolerance test were carried out.At the end of the experiment,the mice were sacrificed and the blood serums were separated.Then the content of triglycerides,total cholesterol,high density lipoprotein cholesterol,low-density lipoprotein cholesterol,fasting glucose,alanine aminotransferase and aspartate aminotransferase were measured according to the instructions of kits.The heart,liver and abdominal fat were taken out and weighed,and then the organ coefficient was calculated.A part of fresh liver were clipped and stained with oil red oxygen to detect the lipid accumulation in the liver.The brown adipose tissue was detected with transmission electron microscopy to observe the structural changes of it and mitochondrial distribution and morphology in it after the drug intervention.Another part of the brown fat and white fat were frozen in liquid nitrogen then the total protein were extracted,and the protein expression of Tyk2,STAT3 and downstream critical protein closely related to lipid metabolism,such as PRDM16,PPARα,PPARγ,UCP1,C/EBP and FAS,were detected by Western blot.二、The mechanisms(一)The effect of Phlorizin on Tyk2/STAT3 signaling pathwayThe protein expression of Tyk2,STAT3 and downstream critical protein closely related to lipid metabolism,such as PRDM16,PPARα,PPARγ,UCP1,C/EBP and FAS,were detected by Western blot.(二)The effect of Phlorizin on Tyk2 siRNA interference miceThe siRAN interference was used to shield Tyk2/STAT3 signaling pathway,and the effects of phlorizin on Tyk2/STAT3 signaling pathway and brown fat function were observed.Results一、Animal experimentPhlorizin can reduce the body weight of obese mice,reduce the accumulation of abdominal fat and decrease the content of triglycerides,total cholesterol,LDL cholesterol,fasting blood glucose.Phlorizin can improve glucose tolerance and insulin resistance and liver lipid deposition in mice.It can also raise the temperature at the interscapular brown fat,improve the damaged state of mitochondria in brown fat cells and restore the thermogenesis function.二、The mechanisms(一)The mechanism study shows that Phlorizin can increase the protein expression Tyk2,STAT3,PRDM16,UCP1,C/EBP、PPARa protein in brown adipose tissue,but has no effect on these protein in white fat.(二)Phlorizin increases the temperature of interscapular and enhance thermogenesis function of brown adipose tissue in Tyk2 siRNA interference mice.at the same time,Phlorizin can improve the levels of Tyk2 mRNA and protein,thus improving Tyk2/STAT3 signaling pathway activityConclusionPhlorizin inhibits obesity through increasing the activity of Tyk2/STAT3 signaling pathway and enhancing energy metabolism of brown adipose tissue to consume more energy of the body.