Effects of copper and its ethylenediaminetetraacetate complex on the antioxidant defenses of the goldfish, Carassius auratus

Copper bioavailability in the tissues of goldfish and antioxidant defenses in the liver of fish were investigated in vivo following 40 days of exposure to different species of copper solutions at different concentrations. Copper seemed to be more concentrated in the gill than in the liver after Cu2+ and copper-ethylenediaminetetraacetate (Cu–EDTA) exposure. The addition of EDTA markedly affected copper adsorption in the gill but had no significant effects in the liver. We also found that in the fish exposed to the concentration of Cu2+ below the Chinese national fishery water quality standard of 0.01 mg/L, superoxide dismutase (SOD) and glutathione S-transferase (GST) activities in liver were stimulated and catalase (CAT) and Se-dependent glutathione peroxidase (Se-GPx) activities were inhibited after 40 days of exposure. Compared to copper exposure, the addition of EDTA did not affect SOD and GST significantly. However, CAT and GPx activity with Cu2+ exposure were significantly different from those with Cu–EDTA exposure.