Effects of fenthion on GSH metabolism, HSP70, acetylcolinesterase activity and lipid peroxidation modulated by piperonyl butoxide in the brain of Oreochromis niloticus

The aim of the present study was to investigate the effects of organophosphorusinsecticide and avicide fenthion modulated by PBO, an inhibitor of cytochrome P450, onGSH metabolism, lipid peroxidation, stress proteins and its neurotoxic potantial in the brainof juvenile Oreochromis niloticus. For this purpose, after the pretreatment of fish with 0.5mg/L PBO for 24-h, the fish were placed in 0.567 mg/L fenthion and 0.5 mg/L PBOcontaining water for 24-h, 96-h and 15-d. tGSH, GSH, GSSG and TBARS contents,GSH/GSSG ratio, GPx, GR, and GST enzyme activities were measured usingspectrophotometric methods and HSP70 contents were determined by using ELISA test.It was determined that fenthion caused increases in GSSG and TBARS contents,decreases in GSH/GSSG ratio and GST enzyme activity in short term exposures; increases intGSH, GSH, and HSP70 contents, GSH/GSSG ratio, GST and GR enzyme activities in longterm exposure. It was found that, in the presence of PBO, fenthion caused decreases intGSH, GSH contents and GSH/GSSG ratio and increases in GSSG, HSP70 ve TBARScontents in short term exposure; decreases in tGSH, GSH contents and GSH/GSSG ratio andincreases in GSSG, HSP70 and TBARS contents in long term exposure. It was alsodetermined that fenthion caused AChE inhibition in all exposure durations, and AChEinhibition effect of fenthion decreased by PBO in long term exposure.In this study, it was shown that the selected concentration of fenthion caused anoxidative stress and this effect of fenthion was not eliminated by the GSH-related defences.PBO increased the oxidative stress effect of fenthion by affecting GSH-related defence, lipidperoxidation and stress proteins. Fenthion caused neurotoxic effects by inhibiting AChEenzyme activity which is decreased by PBO.