Environmental Internal Secretion Interfering Substance-Effects Of Nickel Sulfate Exposure On Oxidative Stress Indicators In Rat Liver And Kidney Tissues

Objectives:To detect malondialdehyde（MDA）content,superoxide dismutase（SOD）activity,nuclear transcription factor NF-E2-related factor 2（Nrf2）and heme oxygenase 1（HO-1）mRNA expression levels and serum aspartate aminotransferase（AST）,alanine aminotransferase（ALT）,creatinine（Cr）,and urea nitrogen（BUN）levels in liver and kidney tissues of rats under the condition of subchronic nickel sulfate（NiSO₄）,to explore lipid peroxidation and antioxidant defense systems of male Wistar rats exposed to NiSO₄.Methods:1.Total of 20 mature SPF male Wistar rats（180-220g）were randomized into normal control groups（0.9%physiological saline equal volume intraperitoneal injection（ip）,5ml/kg/d）,NiSO₄ low-dose group（2.5mg/kg/d.ip）,medium-dose group（5mg/kg/d.ip）and high-dose group（10mg/kg/d.ip）,continuously for 40 days,and the rats were free to eat and drink.The mental state and general activities of the rats were observed throughout the experiment,and the body weight was recorded.2.All rats were killed to collect blood from the abdominal aorta,biochemical analyzer after centrifugation to measure liver and kidney function indicators,including AST,ALT,Cr and BUN.At the same time,collect liver and kidney tissues to prepare samples,and use chemical colorimetry and hydroxylamine method to detect MDA and SOD in liver and kidney tissue;Real-timePCR（RT-PCR）method was used to detect expression levels of antioxidant indicators Nrf2 and HO-1mRNA in rat liver and kidney tissues.Results:1.NiSO₄ can slow down the weight gain of rats:At the 40th day of exposure,the weight gain of rats in the high-dose group was decreased compared to low and middle-dose group（P<0.05）;after the entire exposure period,net increase of body weight in the high-dose group was decreased compared to the low-dose group（P<0.05）.2.Nickel exposure can increase the serum ALT and AST levels and the MDA content in liver tissues,but there is no statistical significance（P>0.05）;SOD activity in liver tissues increases first and then decreases:compared with the control group,SOD activity in the low-dose group showed an upward trend（P>0.05）,and the middle and high-dose groups were decreased（P<0.05）.3.Detection of Nrf2 and HO-1mRNA levels in liver tissue by RT-PCR:（1）Compared with the control group,the relative Nrf2mRNA level in the low and medium-dose groups were increased significantly（P<0.01）,and the high-dose group showed an declining trend（P>0.05）;among the exposed groups,the relative Nrf2mRNA level in the high-dose group was significantly decreased compared to the low and middle-dose group（P<0.01）;（2）compared with the control group,the relative HO-1mRNA level in the low-dose group showed an upward trend（P>0.05）,in the high-dose group was significantly decreased（P<0.01）;between the exposure groups,the relative HO-1mRNA level in the high-dose group was decreased compared to the low-dose group（P<0.05）.4.The levels of BUN and Cr in the medium and high-dose groups were significantly increased compared with the control group（P<0.01）.Between the exposure groups,the levels of BUN and Cr in the medium and high-dose groups were significantly increased compared to the low-dose group（P<0.01）;NiSO₄ exposure can increase MDA in rat kidney tissues（P>0.05）;SOD activity increased first and then decreased:compared with the control group,SOD activity in the low-dose group showed an increased trend,and the middle and high-dose groups showed an decreased trend（P>0.05）;among the exposure groups,SOD activity in the middle and high-dose groups was decreased compared to the low-dose group（P<0.05）.5.Detection of Nrf2 and HO-1 mRNA levels in renal tissue by RT-PCR:（1）Compared with the control group,the relative Nrf2mRNA level in the low and medium-dose groups were increased（P<0.05）,and the high-dose group was significantly decreased（P<0.01）;among the exposed groups,the relative Nrf2mRNA level in the high-dose group was decreased compared to the low and middle-dose group（P<0.05）;（2）compared with the control group,the relative HO-1mRNA level in the low and middle-dose groups showed an upward trend（P>0.05）,and the high-dose group was significantly decreased（P<0.01）;among the exposed groups,the relative HO-1mRNA level in the high-dose group was decreased compared to the low and middle-dose groups（P<0.05）.Conclusion:（1）The levels of metabolites related to renal function were significantly abnormal,and the activities of enzymes related to liver function showed an increasing trend,indicating that NiSO₄ could induce kidney injury by intraperitoneal injection,while has an adverse effect on liver function due to it is still within the scope of compensation.（2）The mechanism of subchronic NiSO₄ induced-liver and kidney injury may be related to oxide stress and activation of Nrf2 antioxidant signaling pathway,and the changes in enzyme activity are synchronized with the expression of antioxidant genes.