Enzymatic Biomarker Measurement and Study on Pollution-induced Antioxidant Enzymes Responses in Freshwater Fish Liver, Brocarded Carp

The acute toxicity of M-DNB (m-dinitrobenzene) to Brocarded Carp and antioxidant enzyme activities in liver of fish were investigated. The acute toxicity test showed that 24h, 48h, 72h, 96h value of median lethal concentration (LC₅₀) at 20-22 square were 27.19, 20.65, 16.17 and 14.04mg/L, respectively. Fish was exposed to different concentrations (1/6LC₅₀, 1/4LC₅₀, 1/3LC₅₀, 1/2LC₅₀) and killed at 6, 12,18, 24 and 30 day after exposure. The activities of Superoxide dismutase (SOD), Catalase (CAT) and Glutathione peroxidase (GPx) in liver tissue were analyzed. The results indicated the activities of SOD, GPx were induced in all treatment groups at post-exposure, they were higher than those of the control group (p < 0.05). The activity of CAT was significantly induced except for I/6LC₅₀ treatment group. Moreover, the SOD and GPx activities of the control group were stable, except that the CAT activity increased 1-fold. The results demonstrated that the activities of liver antioxidant enzyme in Brocarded Carp might be the promising biomarker of M-DNB exposure. Therefore it was suggested that SOD, GPx and CAT could be used as biomarker of nitroaromatics compounds, when their pollutions affected living beings in aquatic environment. But, the order of the sensibility and stability for 3 kinds antioxidant enzymes was GPx>SOD>CAT.