Nitrobenzene Induced Oxidative Stress In Liver Of Carassius Auratus

This paper studied the oxidative stress of Nitrobenzene(NB) on the liver of Carassius auratus at the molecular level of toxicity. Under the indoors stimulant conditions, the activities of superoxide dismutase(SOD), catalase(CAT),glutathione S-transferase(GST) and the lipid peroxidation(LPO) in the liver of fish after different exposure time were determined, moreover, this paper tried to probe into the effect mechanisms of the oxidative damage to the liver of fish, which provided the scientific foundation for the fully estimate of NB's ecological toxicology on aquatic organism. In the present study, the exposure concentration was 0.5mg/L, 1.0mg/L, 5.0 mg/L and 10.0mg/L, the exposure time was 5,10 and 15 days respectively. The results showed that with the exposure time prolonged, the activities of SOD was inhibited initially and then increased significantly; whereas the activities of CAT and GST were induced firstly and then had a tendency to decrease, which suggests that the activities of enzymes were disrupted and had a continuous variance. In addition, the SOD activities were decreased remarkably after 5 days exposure of 0.5mg/L NB solution, which reveals its sensitivity to NB; while CAT and GST activities were sensitive to higher NB solution(5.0mg/L and 10.0mg/L), however, no evident concentration-effect relations were found. By determining the content of malondialdehyde (MDA),we found that after 5 days exposure of 5.0mg/L and 10.0 mg/L NB, the lipid peroxidation occurred in the liver of fish, and with the exposure time prolonged, the content of MDA in the liver of fish exposed to lower NB solution (0.5mg/L and 1.0mg/L)increased significantly(P<0.05),while significant differences (P<0.001)in LPO were found after 15 days at higher concentrations tested(0.5mg/L and 1.0mg/L) when compared to controls, suggesting oxidative damage severely. In conclusion: when NB metabolized in the liver of Carassius auratus, redox cycling were produced, resulting in the changes of the activities of the antioxidant enzymes and then lipid peroxidation occurred, and this might be an important mechanism of NB in Carassius auratus liver injury.