Involvement of cholinesterases in oxidative stress induced by chlorpyrifos in the brain of Japanese quail.

Chlorpyrifos is a widely used organophosphate pesticide (OP). In birds and mammals OP exhibits a toxic effect via inhibition of cholinesterases [acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)] and through oxidative/nitrosative stress. In this study, the influence of chlorpyrifos on cholinesterase activity, parameters of oxidative stress [malondialdehyde (MDA); glutathione (GSH); superoxide dismutase (SOD); nitrite concentration (NO2-); hydrogen peroxide (H2O2)], and inflammatory parameter [activity of myeloperoxidase (MPO)] in the brain of Japanese quail (Coturnix japanica) was examined. The study was conducted on a total of 60 male Japanese quails (one control and 5 experimental groups, n = 10), 3 to 4 wk old. Quails were administered by gavage chlorpyrifos (CPF) for 7 consecutive da at doses of 0.375 mg/kg BW, 0.75 mg/kg BW, 1.5 mg/kg BW, 3 mg/kg BW, and 6 mg/kg BW. Our studies have shown that all doses of CPF significantly inhibited both cholinesterases in brain: AChE from 22.74 to 37.83% and BChE from 19.53 to 61.9%, and that inhibition was dose dependent. Also, CPF has led to an increase in the concentration of MDA, GSH, NO2-, and H2O2 and activity of SOD and MPO. Overall, these results support the hypothesis that CPF causes oxidative stress and inflammatory response. This research was carried out on quails because there is hardly any or not enough data about the neurotoxic effect of CPF and especially about its influence on oxidative stress in birds. This study is highly important because we are witnessing massive avian mortality in certain countries due to pesticides.