Effects of organophosphorous compounds on fatty acid compositions and oxidative phosphorylation system in the brain of rats

Effects of organophosphorous compounds, O,O-dimethyl O-4-nitro-m-tolyl phosphorothioate (MEP), O-ethyl O-p-nitrophenyl phenylphosphonothioate (EPN) and O-(4-cyanophenyl) O-ethyl phenylphosphonothioate (CYP), on the fatty acid composition and the subsequent effects on the oxidative phosphorylation system in the brain of rats were studied. After 6 days exposure in pesticides, polyunsaturated fatty acids in brain free fatty acid fractions of CYP treated rats decreased, and the unsaturation index in them were lower than those in the control rats. The polyunsaturated/saturated ratio (P/S ratio) in brain total lipids of CYP treated rats was lower than that in the control. The fatty acid composition in the brain of EPN treated rats had the same inclination as that of CYP treated rats. In the P/S ratio and unsaturation index in serum no difference was observed between CYP treated rats and the control, therefore CYP could affect the fatty acid composition in the rat brain directly. Free fatty acid contents in the brain of EPN and CYP treated rats decreased after 6 days exposure. Activities of complex I of brains were significantly higher in the EPN and CYP exposed rats than in the control rats in spite of the fact that no difference of ATP productivity was observed between them. These results suggest that EPN and CYP may affect the free fatty acid content, especially the polyunsaturated fatty acid content and consequently the enzyme activities in the oxidative phosphorylation system in the brain. Those phenomena, however, were not observed after 28 days exposure in pesticide, therefore those effects may be a passing phenomenon in an acute stage.