Effects of Cadmium on the Expression of Antioxidant Enzymes, Oxidative Stress and Apoptosis in Primary Hepatocytes of Carassius Auratus

Abstract

The primary hepatocytes of Carassius auratus were incubated with 0, 0.01, 0.1, 1, 10 and 100 mg/l Cadmium(Cd2+) at 25°C for 8h in vitro. The results showed that the hepatocytes survival rate in the 1, 10 and 100 mg/l Cd2+ treated groups were significantly lower than that in the control, the percentage of apoptotic hepatocytes significantly increased in 0.1, 1 and 10 mg/l of Cd2+ treated groups, intracellular reactive oxygen species(ROS) and malondialdehyde (MDA) content significantly increased in 0.1, 1, 10 and 100 mg/l Cd2+ treated groups, typical DNA ladder was observed in 0.1, 1 and 10 mg/l Cd2+ treated groups, and ruleless DNA fragment occurred in 100 mg/l Cd2+ treated group. The activities of the antioxidant enzymes and the expression of their isozymes activities have similar change tendency, compared with the control group, the activities of superoxide dismutase (SOD) and their isozymes were activated by low concentration of Cd2+ (0.1 and 1 mg/l), however, their activities were inhibited by high concentration of Cd2+ (10 and 100 mg/l), especially, the special isozyme (SOD1) was found in the patterns of SOD isozymes in 0.1 and 1 mg/l Cd2+ treated groups, the activities of peroxidase(POD) and its isozymes significantly reduced with a concentration-dependent manner in all Cd Cd2+ treated groups, the activities of catalase(CAT) and its isozymes significantly decreased in higher concentration Cd2+ treated groups (1, 10 and 100mg/l). The results suggested that Cd2+ could damage the activities of the antioxidant enzymes and cause oxidative stress, lipid peroxidation, DNA fragmentation, apoptosis and necrosis in primary hepatocytes, contributing to the liver toxicity induced by Cd2+.