Oxidative Damage Of Mice Kidney Induced By T-2 Toxin And Regulatory Mechanism Of Nrf2 Pathway

T-2 toxin is a common and unavoidable environmental and grain pollutant,which can accumulate in the kidney and cause kidney damage.T-2 toxin has great harm to human and animal health,animal and plant food safety,economic and trade development.Kidney is the main target organ of T-2 toxin attack,which can induce oxidative stress and lead to structural damage and functional disorder of kidney.ROS can be produced under oxidative stress,which can induce mitochondrial damage and activate mitochondrial apoptosis.The only study has shown that T-2toxin can lead to apoptosis of renal cells,but the role of apoptosis in T-2-induced renal injury and its mechanism are unclear.Oxidative stress is the pathological basis of many diseases.Nrf2pathway is an important antioxidant pathway,which is involved in the regulation of renal oxidative damage caused by various mycotoxins.However,whether the Nrf2 pathway is involved in the renal injury caused by T-2 toxin is still uncertain.In this study,the relationship among kidney injury,oxidative stress and Nrf2 pathway was taken as the breakthrough point,and Nrf2 pathway involved in the regulation of T-2 toxin induced kidney injury was taken as the theoretical hypothesis.48 male Kunming mice(6 weeks age)were randomly divided into four groups:0mg/kg B.W.(control group,CG),0.5mg/kg B.W.(low-dose T-2 toxin group,LG),1.0mg/kg B.W.(middle dose T-2 toxin group,MG)and 2.0mg/kg B.W.(high dose T-2 toxin group,HG).The experimental period was 28 days.The model of kidney injury induced by T-2 toxin was established.The growth status(body weight and mental state),kidney structure injury(kidney coefficient,kidney microstructure and ultrastructure),renal function(serum BUN,SCR,Cys-C and?2-Mg;urine NAG and?2-Mg),apoptosis(TUNEL staining,nuclear ultrastructure of renal tubular epithelial cells,the MMP and the expressions of key factors of mitochondrial apoptosis),oxidative stress(the levels of ROS,MDA,GSH and the activities of SOD and CAT),the expressions of key factors of Nrf2 pathway(Nrf2,HO-1,NQO1,GCLC,GCLM),and correlation analysis of oxidative stress,key factors of apoptosis and Nrf2 pathway.The aim of this study was to investigate the oxidative damage of mice kidney induced by T-2 toxin and the regulatory mechanism of Nrf2 pathway.The experimental results are as follows:(1)Compared to the CG,the BW was decreased in the MG and HG(P<0.05,P<0.01).(2)Compared to the CG,the kidney coefficient was decreased in all T-2-treated mice.T-2 toxin caused the microstructural and ultrastructural damage of kidney.Compared to the CG,the contents of BUN and?₂-Mg were markedly increased in all T-2-treated groups(P<0.05,P<0.01);the contents of SCR and Cys-C in serum were markedly increased in the MG and HG(P<0.01);the contents of?₂-Mg and NAG in urine were markedly increased in the MG and HG(P<0.01).(3)Compared to the CG,the percentage of TUNEL-positive nuclei was increased in the MG and HG(P<0.05,P<0.01).The autrastructural observation of kidney showed that T-2 toxin caused the apoptosis.Compared to the CG,the MMP was significantly decreased in the MG and HG(P<0.05,P<0.01).Compared to the CG,the activities of Caspase-3 and Caspase-9 were markedly increased in all T-2-treated groups(P<0.05,P<0.01).Compared to the CG,the m RNA and protein expressions of Bax was increased in the MG and HG(P<0.01),while the m RNA and protein expression of Bcl-2 was significantly decreased in the MG and HG(P<0.01).(4)Compared to the CG,the concentration of ROS was increased in the MG and HG(P<0.05,P<0.01);the concentration of MDA was increased in all T-2-treated groups(P<0.01);the GSH content was decreased in the MG and HG(P<0.05,P<0.01);the SOD activity was decreased in the MG and HG(P<0.01);the CAT activity was decreased in the MG and HG(P<0.05,P<0.01).(5)Compared to the CG,the m RNA expression and nuclear protein expression of Nrf2 were increased in all T-2-treated groups(P<0.05,P<0.01).These results pointed that T-2 toxin treatment increased the m RNA and protein expression of Nrf2.Compared to the CG,the m RNA expressions of NQO1,GCLC,and GCLM were significantly increased in the MG and HG(P<0.01).The m RNA expressions of HO-1 was increased in all T-2-treated groups(P<0.05,P<0.01).This result showed T-2 toxin treatment increased the m RNA expressions of Nrf2downstream target genes.(6)Pearson correlation analysis showed that renal oxidative stress induced by T-2 toxin was positively correlated with mitochondrial pathway apoptosis and Nrf2 pathway,and Nrf2 pathway was positively correlated with mitochondrial pathway apoptosis,indicating that oxidative stress is the promoter of mitochondrial apoptosis pathway and Nrf2 pathway activated by T-2 toxin.Conclusion:T-2 toxin induced renal oxidative stress,damaged the mitochondria in renal tissue cells,activated the oxidative stress mediated mitochondrial apoptosis and damaged the renal cells,and the Nrf2 pathway is involved in the T-2-induced renal injury.