The Protect Role Of Resveratrol For The Oxidative Stress Injury Of Diabetic Kidney

Objective:Diabetic nephropathy DN is the most common microvascularcomplication of diabetes.In recent years,the morbidity of DN isincreasing,which is one of the main cause resulting in the end stage renaldisease,ESRD.For this,it has been an area of research which focus on clarifingthe pathogenesis and seeking the methods to prevent and treat DN.A lot ofresearches show that oxidative stress plays an important role as apathophysiological mechanism in the etiology of DN.Hyperglycemia leads toproduct a mass of reactive oxygen species in renal.An overdose of ROS canactive a variety of signal transduction pathway related to microvascularcomplication and cause cell damage resulting in the excessive accumulation ofextracellular matrix,which speeds up the progress of renal fibrosis.Organism has a complex response system to the oxidative stress inducedby ROS damage and produces a series of helpful proteins,which can alleviateoxidative stress injury of cells.Recently,nuclear factor erythriod2-relatedfactor2(Nrf2) and its cytoplasmic adaptor protein had been proved to be thekey regulator of antioxidant.Nrf2is the receptor of ectogenic toxin andoxidative stress,which plays an important role in protecting cells according tointeract with the antioxidative response element to induce the expression ofphase II detoxifying enzymes such as heme oxygenase(HO-1).Resveratrol,a kind of polyphenolic phytoalexins,is reported to have manybeneficial effects on human health, such as antioxidation, liver protection,antianaphylaxis,antineoplastic function,regulating blood fat,neuroprotectionet al.In recent years,resveratrol has also been found to play an important rolein protecting diabetic nephropathy according to antioxidation.However,themechanism of its antioxidation and whether it can influence the Nrf2-AREsignal pathway is rarely explored at home and abroad. In the present research,the activity of T-SOD and expression ofMDA,Nrf2and HO-1were observed in the renal tissues of STZ-induceddiabetic mouse according to the methods of xanthine oxidase, thibabituric acid(TBA), immunohistochemistry and western blot, in order to explore themechanism of protection of resveratrol for the renal tissues of diabetic mouseand provide theoretical basis for finding new control methods of DN.Methods:Seventy-two healthy uninephrectomized male CD-1mice wererandomly divided to two groups:the control group and the model group.Themice of model group received a singal intraperitoneal injection of STZ(dissolved in0.1mol/L citrate buffer pH4.5) at a dose of130mg/kg.Incontract,the mice of control group only received an injection of same volumeof sodium citrate.The diabetic model was considered to be successful whenthe blood glucose was≥16.7mmol/L and the glucose in urine was+++～++++after72hours of STZ injection.The model group is randomly dividedinto two groups:the diabetic group(DM) and the resveratrol-treateddiabetic(DR) group.The control group is also divided to two groups:thenormal control group(CN) and the resveratrol control group(CR).Group CRand DR were treated with resveratrol(5mg/kg/d) and the mice of group CNand DM were treated with the same volume of solvent,carboxymethocel. At4,8and12weeks after the onset of diabetes,the weight of mice of each groupwere measured,and then,24h urines were collected in metabolic cage for themeasurement of urine albumin.Six mice were sacrificed for each grouprespectively and measure their serum creatinine(Scr) and blood ureanitrogen(BUN),the renal cortical tissues were removed and used for detectingthe expression of Nrf2,HO-1with immohistochemistry and western blot andmeasuring the content of MDA and the activity of T-SOD. The date wasrepresented in x±s, one-way analysis of variance was used in date analysis.Results:1Renal index:The renal index of group DM was obviouslyhigher than group CN at all time points (P＜0.01). The data of group DR wasdecreased slightly at4thweek (P＞0.05), however the data is decreasedsignificantly at8thand12thweek compared with group DM(P＜0.05). 2Biochemical indicators:At4,8, and12weeks, The data could not beobserved any significant difference between the group of CN and CR(P＞0.05). Renal index,24-hours urinary protein,BUN and Scr were increased ingroup DM compared with group CN(P＜0.01),however those were decreasedin group DR than in group DM(P＜0.05).3The content of MDA:At all time points,there was no significantdifference found between group CN and CR(P＞0.05).The content of MDA ingroup DM was up-regulated compared with group CN(P＜0.01),but obviouslydecreased after treatment with resveratrol(P＜0.05).4The activity of T-SOD:At all time points,there was no significantdifference found between group CN and CR(P＞0.05).The content of MDA ingroup DM was decreased compared with group CN(P＜0.01),but obviouslyincreased after treatment with resveratrol at the8thand12thweek(P＜0.05).5Immunohistochemical staining and Western blot showed that theexpression of HO-1and Nrf2were nearly the same in group CN and CR(P＞0.05). At all time points,the total and nucleus protein expression of Nrf2werehigher in group DM than group CN and further increased in group DR ascompared with group DM(P＜0.01).HO-1protein was expressed lower ingroup DM than that in group CN at the4thweek but higher at the8thand12thweek and expressed higher in group DR than group DM of the same time(P＜0.01).Conclusion:1There was significant oxidative stress in renal tissues of diabetic mice.2Resveratrol is helpful to decrease the content of MDA,increase theactivity of T-SOD and induce the expression of Nrf2and HO-1,whichameliorates the oxidative stress in renal cortex of diabetic mice.3Resveratrol has a protective effect for diabetic nephropathy and itsprotective effects probably depend on inhibiting the oxidative stress response.