The Effect Of Adipokine Zinc-?2-glycoprotein On Lipid Metabolism Of Mice After Dexamethasome Treatment

Stress is the systemic non-specific adaptive response caused by the body's inadaptability to changes in the in vivo and in vitro environments.Under stress conditions,the hypothalamic pituitary adrenal(HPA)axis is instantaneously activated,and then the adrenal cortex releases amounts of glucocorticoids.Dexamethasone(DEX)is a synthetic analogue of glucocorticoids.Many studies use DEX to simulate stress and explore the effects of stress on the body.Studies have shown that DEX treatment can disrupt body lipid metabolism.ZAG appears to be a lipid mobilization factor under normal conditions,but it is still unclear whether it contributes to energy supply to the body under DEX-simulated stress conditions.Therefore,in this study,we used DEX to simulate stress,and ZAG overexpression and knockout as a model to study the role of ZAG in body fat metabolism under stress.1 Application of genome-wide microarray screening the related genes in adipose tissues of ZAG knockout miceWe employed wild-type and ZAG systemically knockout C57BL/6 mice as models,mice were divided into two groups;CON group and ZAG-/-group.After feeding for one week,all the mice were fasted.Six hours after fasting,the mice were weighed and sacrificed by exsanguination.Visceral adipose tissue was collected.Genome-wide microarray was applied in screening differentially expressed genes between ZAG-/-and control groups in the visceral adipose tissue.The results showed that there were 179 genes differentially expressed genes between ZAG-/-and control groups in the visceral adipose tissue of which 26 genes were significantly upregulated and 153 genes were significantly downregulated.The biological function of the up-regulated genes in the ZAG knockout group mainly focused on protein binding,mitochondria,adipocyte differentiation,metal ion binding,etc.The biological functions of the down-regulated genes in the ZAG knockout group were mainly concentrated in the cell membrane,endogenous immune response,and negative control of the apoptosis.The pathways involved in the expression of up-regulated genes in the visceral fat of the ZAG knockout group mainly include insulin signaling pathways,transcriptional misregulation in cancer,fatty acid degradation,and glyceride metabolism.The pathways involved in down-regulating genes in visceral fat of ZAG knockout group mainly include NF-?B signaling pathway,chemokine signaling pathway,and arachidonic acid metabolism.The key genes involved in lipid metabolism,Lpinl and GPAM,which are up-regulated after ZAG knockout,contribute to the synthesis of glycerol lipids.2 Effects of ZAG knockout on fat metabolism of dexamethasone-treated miceIn our experiment,we employed wild-type and ZAG systemically knockout C57BL/6 female mice as models,mice were divided into four groups:CON group,ZAG-/-group,DEX group and DEX+ZAG-/-group respectively.DEX group and DEX+ZAG-/-group were given 5 mg/kg dexamethasone supplementary deionized water ad libitum.After feeding for one week,all the mice were fasted.Six hours after fasting,the mice were weighed and sacrificed by exsanguination.Lipid metabolism related genes and proteins in visceral fat were determined by quantitative real-time polymerase chain reaction and western blotting.Plasma triglyceride(TG)and non-esterified fatty acid(NEFA)level were measured by the automatic biochemical analyzer.The results showed that plasma TG and NEFA content were no difference between CON and ZAG-/-groups.While,plasma TG and NEFA content in the DEX+ZAG-/-group was significantly reduced compared with DEX group.Similarly,p-HSL and ATGL protein expression in visceral fat were no change between CON and ZAG-/-groups.While,p-HSL expression in DEX+ZAG-/-group was significantly increased compared with DEX group.Compared with DEX group,ATGL protein expression in DEX+ZAG-/-group was showed increased trend.The expression of FAS and adiponectin protein in visceral fat were significantly increased after ZAG knockout.In conclusion,knocking out of ZAG under the DEX-treated model in this experiment had significantly decrease the plasma TG and NEFA content.And the effect caused by the decreased ability of lipolysis in visceral fat after ZAG knockout.3 The effects of adipokine zinc-?2-glycoprotein on adipose tissue metabolism after dexamethasone treatmentIn our experiment,C57BL/6 male mice were randomly divided into two groups:The DEX group mice were injected with the CON compound via tail vein at 9:00 am and then they were intraperitoneally injected with 1mg/kg dexamethasone 21-phosphate disodium salt dissolved by saline at 10:00.The dexamethasone and zinc-?2-glycoprotein(DEX+ZAG)group mice were injected with the ZAG compound via tail vein at 9:00 am and then they were intraperitoneally injected with 1mg/kg dexamethasone 21-phosphate disodium salt dissolved by saline at 10:00.The mice were treated every other day and treated for 5 time altogether and fasted after the fifth injection.Six hours after fasting,the mice were weighed and sacrificed by exsanguination.Our results showed that the expressions of?-adrenoreceptor(?-AR)/cyclic adenosine monophosphate/protein kinase a(PKA)pathway,lipid mobilization,energy metabolism related genes and proteins were determined by quantitative real-time polymerase chain reaction and western blotting.Plasma non-esterified fatty acid(NEFA)level was measured by the automatic biochemical analyzer.The results indicated the plasma NEFA was obviously increased after ZAG overexpression.Overexpressed ZAG increased the expression of ?3-AR and phosphorylated PKA protein compared with DEX group.For lipometabolism,overexpressed ZAG significantly increased protein abundance of phosphorylated hormone-sensitive lipase.For energy metabolism,ZAG significantly increased the protein expression of carnitine palmitoyltransferase la(CPTla)and Cytochrome c oxidase subunit 1(COX1)compared with DEX group.In conclusion,overexpression of ZAG activates the ?-AR-cAMP-PKA pathway,which in turn promotes the expression of lipolytic key enzymes p-HSL and ATGL to accelerate the lipolysis.More NEFA production could induced increase of plasma NEFA content and increased levels of ?-oxidation in WAT.