Interactions among Antioxidant Defenses in Liver of Rainbow Trout (Oncorhynchus mykiss) Exposed to Cadmium

Abstract

Rainbow trout (Oncorhynchus mykiss) (mean weight 180 ± 10 g) fed diets deficient in ascorbic acid, tocopherol, both, or neither were exposed to one of three cadmium concentrations (0, 2, or 4 μg Cd/L). After 181 d of exposure, liver and whole blood were sampled. Cadmium exposure was found to significantly increase the Cd content in liver, especially in fish fed a diet deficient in ascorbic acid. Hepatic stores of ascorbic acid decreased in fish exposed to Cd and in fish fed diets deficient in tocopherol and ascorbic acid. Depletion of tocopherol in liver occurred only in those fish fed a diet deficient in tocopherol and exposed to Cd. Superoxide dismutase activity in liver increased with Cd exposure and with dietary deficiencies of tocopherol and ascorbic acid, while catalase was inhibited by exposure to Cd alone. Glutathione peroxidase activity was unaffected by Cd but was lower in fish fed a diet deficient in both tocopherol and ascorbic acid. Erythrocyte fragility, measured by spontaneous hemolysis of red blood cells in physiological saline, was increased by Cd exposure and the deficiencies of dietary tocopherol and ascorbic acid.