Effects of chronic exposure of waterborne copper on the antioxidant system and tissue accumulation in golden trout (Oncorhynchus mykiss aguabonita)

We assessed the acute and chronic effects of copper (Cu2+) on the antioxidant system in golden trout (Oncorhynchus mykiss aguabonita). The median lethal concentration after 96 h was determined as 0.24 mg L−1. We then used 0.06 (L) and 0.12 mg L−1 (H) Cu2+ to assess the responses of the antioxidant system to long-term exposure. The activities of superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase, reduced glutathione, and oxidized glutathione were measured in gill and liver tissue after 24 and 72 h and 7, 14, 21, and 28 days of exposure, as well as after 16 days of recovery in Cu2+-free water. Cu2+ accumulated to a greater extent in the liver than in the gill (0.61–0.75 mg kg−1 vs. 24.0–69.9 mg kg−1 in L group and 0.98–1.47 mg kg−1 vs. 33.3–66.03 mg kg−1 in H group). In the gill, we observed increases in the activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as in the concentrations of reduced glutathione and oxidized glutathione. In the liver of L group, we observed increases in glutathione reductase activity and in the levels of reduced glutathione and oxidized glutathione. In L group, the activity of superoxide dismutase and reduced glutathione content increased after 24 h and then decreased over time, while catalase and glutathione reductase activity and oxidized glutathione levels increased. Data from the recovery period indicated that higher concentrations of Cu2+ may induce irreversible oxidative damage to the gill of golden trout.