Oxidative effects of fenthion on NAC and BSO modulated glutathione metabolism in the liver and kidney tissues in Oreochromis niloticus

This study was designated to understand the effects of organophosphate insecticide and avicide fenthion on cellular redox state and the role of GSH on this process in the liver and kidney of Oreochromis niloticus. NAC and BSO, modulators of GSH metabolism, were intraperitoneally injected and tGSH, GSH, GSSG and MDA levels, GSH/GSSG ratio and GPx, GR, GST and ?-GT enzyme activities were measured spectrophotometrically at 24-, 48- and 96-h. Depuration periods of 24-, 48- and 96-h were also maintained to evaluate the changes in fenthion toxicity. Fenthion increased GST and decreased GPx activities and caused a time-dependent depletion in tGSH and GSSG levels in the liver tissue during treatment periods. Decline in tGSH, GSH and GSSG levels, and elevation in GST and ?-GT enzyme activities by BSO injection were observed. No change was found by fenthion exposure in lipid peroxidation levels in the liver tissue, while NAC injection caused a significant decrease in these levels. A significant decrease was observed tGSH and GSH levels and GST enzyme activities in the kidney tissue during treatment periods. On the contrary to liver tissue, a significant increase was observed in tGSH and GSH levels and GST activity in kidney by BSO. NAC application eliminated the decreasing effects of fenthion on GST activity in this tissue. Increasing effect of fenthion on lipid peroxidation levels was multiplied by BSO and alleviated by NAC. Decline in tGSH and GSH levels which occurred in treatment period were maintained in both tissues during depuration periods; and elevation in lipid peroxidation levels were observed during same periods. GST and GPx enzyme activities and tGSH and GSH levels were found to be useful indicators to evaluate the effects of fenthion. BSO injection revealed the significance of GST mediated GSH conjugation on the detoxification process of fenthion and its phase I metabolites. NAC application was useful to avoid the toxic effects of fenthion in acute periods, while it caused an increase in the oxidative toxicity of fenthion in prolonged periods. Depuration period for 96-h was not adequate to eliminate the fenthion-induced changes. Key Words: Fenthion, N-acetylcysteine, Buthionine sulfoximine, Glutathione, Tissue