Study On The Influence Of Arsenic To Nrf2 Related Gene Expression And The Antioxidant Indexs

Objective: To observe the influence of arsenic to the damage of rabbit skin tissue cutinization to discuss the effect of arsenic to antioxidant enzymes levels、the content of8-hydroxy-2’-deoxyguanosine(8-OHdG) 、 and malonyldialdehyde(MDA)of rabbit skin tissue;to analysis the content of arsenic metabolites in urine;to discuss the correlation between the skin tissues antioxidant levels and arsenic methylation levels; to analysis the influence to mRNA expressions of Keap-1/Nrf2 pathway and GCLC.Methods: 30 clean grade New Zealand male rabbits were divided into 5 groups averagely and randomly:0(control group)、0.075(1/100 LD50)、0.15(1/50 LD50)、0.375(1/20 LD50)、0.75(1/10LD50). The treatment was conducted with drinking water for 12 weeks consecutively. To observe the influence of arsenic to rabbit skin tissue keratinization damage through electron microscopy. The content of HO-1、MPO、8-OHdG、MDA and the activity of CAT、GSH-Px in rabbit skin tissue were determined by appropriate kits.Meanwhile, the content of urine arsenic metabolites including iAs(Ⅲ) 、iAs(Ⅴ)、MMA、DMA were detected through HPLC-HGAFS to analyze the level of arsenic metabolic(PMI、SMI).The mRNA expression level of Keap1 、 Nrf2 and GCLC were determined by Real-time PCR.Results : Cutin anomalies in rabbit skin tissues appeared in the 0.150mg/(kg.w)arsenic exposure group. The degree of keratinization damage was intensified with the increasing dose of arsenic exposure.Rabbit skin tissues appeared keratinization damage obviously, the nucleus are serious irregular, and abnormal chromatin gathered in0.750 mg/(kg.w) arsenic exposure group.Comparing with the control group,the content of HO-1 and the activity ofCAT and GSH-Px were lower in 0.150、0.375、0.750 mg/(kg.w)arsenic exposure groups(P<0.05).The activity of GSH-Px was lower in 0.750 mg/(kg.w)arsenic exposure groups(P<0.05).The content of 8-OHdG was higher in 0.750 mg/(kg.w)arsenic exposure group in rabbit skin tissue(P<0.05). The content of DMA was higher in0.375、0.750mg/(kg.w) arsenic exposure group in rabbit skin tissue(P<0.05). Compared with the control group,the content of TAs、As(Ⅲ)、DMA in 0.750 mg/(kg.w) arsenic exposure group and the content of MMA in 0.375、0.750 mg/(kg.w) arsenic exposure groups in rabbit Urine、the values of PMI in each arsenic exposure groups and the values of SMI in 0.150、0.375、0.750(mg/kg.w) arsenic exposure groups were higher(P<0.05).There are a negative correlation between HO-1、GSH-Px activity levels and the content of MMA、the values of PMI(P<0.05). There are a positive correlation between the content levels of MDA、8-OHdG and the content levels of MMA、the value of PMI(P<0.05).With the arsenic exposure dose increasing, there is a decreased trend at first and then is increased trend of Keap-1 mRNA expression in rabbit skin tissues compared the control group to 0.750mg/(kg.w)arsenic exposure group.The Keap-1 mRNA expression level was higher in 0.750 mg/(kg.w)arsenic exposure group and lower in 0.075 mg/(kg.w)arsenite exposure group(P<0.05). With the increasing dose of arsenic exposure, there is a first increased and then decrease of Nrf2 、 GCLC mRNA expression compared the control group to 0.750 mg/(kg.w)arsenite exposure group. Nrf2 m RNA expression in 0.075、0.150mg/(kg.w)arsenic exposure group and GCLC mRNA expression in 0.075mg/(kg.w)arsenic exposure group were higher.Nrf2 mRNA expression in 0.750mg/(kg.w)arsenic exposure group and GCLC m RNA expression in 0.375 、 0.750mg/(kg.w)arsenic exposure group were lower(P<0.05). Conclusion:The chronic arsenic exposure promoted arsenic methylation process with the increasing dose of arsenic. The content of arsenic metabolites MMA and the PMI increased with the increasing arsenic exposure dose to inhibit related antioxidant enzymes, the decreased content or activity of antioxidant enzymes leads to a reduced antioxidant level and to oxidative damage. 0.075、0.150 mg/(kg.w)arsenic exposure dose activated Keap-1/Nrf2-ARE pathway which inducesan increased Nrf2 mRNA expression and regulates GCLC mRNA expression to maintain oxidative stress balance. 0.750 mg/(kg.w)arsenic exposure dose inhibited Keap-1/Nrf2-ARE pathway, Nrf2 mRNA expression decreased and regulated GCLC mRNA expression, which leads to oxidative damage, antioxidant levels reduced.