Acute and chronic effects of copper and cadmium on oxidative stress biomarkers in Gambusia holbrooki

Abstract

Metallic contamination is widespread, particularly in areas impactedbyhumanactivities,andhasbecomearelevantenvironmentalconcern.However,thetoxicologicaleffectsofmetalsonfish requireadditionalcharacterization.Thus,thepurposeofthisstudy was to determine the oxidative stress response in liver and gills of Gambusia holbrooki, exposed to copper and cadmium. Fish were exposed for 96h (acute exposure) and 28 days (chronic exposure) to the selected compounds. Several oxidative stress biomarkers were evaluated: glutathione-S-transferases (GSTs), catalase (CAT), glutathionereductase(GR),glutathioneperoxidase(GPx)andlipid peroxidation (thiobarbituric acid reactive substances, TBARS). The results indicate that copper caused an inhibition of GSTs and GR activity in G. holbrooki after chronic exposure. On the other hand, acute exposure to cadmium caused significant increases of the enzymatic antioxidant defense (GSTs and GR activity in gills and liver tissues) of fish. Cadmium chronic exposure also elicited a significant reduction effect of lipid peroxidation in gill tissue; then again, cadmium chronic exposure was responsible for significant increase in this parameter in hepatic tissue. Copper acute exposure also caused significant reduction in lipid peroxidation in liver tissue: similarly, gill and hepatic tissue also evidenced strong reduction in TBARS levels, after chronic copper exposure. These results, in general terms, show that exposure of fish to ecologically relevant concentrations of metals can result in measurable damage.