Biochemical Indicators of Oxidative Stress in Fish from Polluted Littoral Areas

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Abstract
Several biochemical parameters have been analyzed in the livers offish from south Atlantic Spanish littoral areas exhibiting different pollution levels. Mugil sp. (grey mullet) from the Huelva Estuary contained higher concentrations of metals, such as Fe and Cu, than those from a reference area (Cádiz Bay). Similarly, sediments from Huelva showed high concentrations of polyaromatic hydrocarbons, polychlorinated biphenyls, and pesticides. The contaminated animals were subjected to oxidative stress, as indicated by their oxidized glutathione redox status, but showed low malondialdehyde and lipohydroperoxide levels. A battery of antioxidant enzymes increased simultaneously in contaminated fishes, including glutathione peroxidase, superoxide dismutase, catalase, glucose-6-P dehydrogenase, and glutathione reductase. These data suggest that contaminated fish were well protected from oxidative stress. Highly significant increases were also observed in cytochrome P-450-associated ethoxyresorufin-O-deethylase activity, and soluble and membrane-bound glutathione-S-transferase, in response to the high levels of organic xenobiotics. We propose that antioxidant enzymes and glutathione-S-transferase might be useful tools for the biomonitoring of environmental pollution.