Cypermethrin: Oxidative stress and genotoxicity in retinal cells of the adult zebrafish

Cypermethrin (CM), widely used for control of indoor and field pests, is one of the most common contaminants in freshwater aquatic systems. We evaluated CM genotoxicity and the activities of superoxide dismutase (SOD) and catalase (CAT) in retinal cells of adult zebrafish. Histological and immunofluorescence techniques show the presence of apoptotic cells in the zebrafish retina after 9 d of treatment with 0.6 mu g/L CM. Histone gamma-H2AX, a marker of DNA damage, was detected in both outer and inner nuclear layers; caspase-3, an apoptotic marker, was detected in the outer nuclear layer. In the comet assay, the cells were sensitive to hydrogen peroxide induced DNA damage, showing a dose-dependent response. We observed a positive comet assay response to CM that was dose- and time-dependent. Following exposure to CM, SOD and CAT enzyme activities, and sod and cat mRNA levels, increased. These results indicate that CM causes DNA damage and oxidative stress and can induce apoptosis in retinal cells.