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Abstract: Organophosphate (OP) pesticides are among the most widely used synthetic chemicals for controlling a wide variety of pests. Chlorpyrifos (o,o′-diethyl-o-3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) is among the leading OP pesticides used extensively throughout the world including India while methyl parathion (o,o-di methyl-o-p-nitrophenyl phosphorothioate, MPT) another OP compound, widely used as insecticide and acaricide to control many biting or sucking pests of agricultural crops. Present study was carried out to compare the chronic toxicity of CPF and MPT, their potential to generate oxidative stress and ameliorating effects of antioxidant vitamins in brain of rats. Results of the present study clearly demonstrated that the oral exposure of CPF or MPT, generated oxidative stress in different parts of rat brain consequently accumulating malondialdehyde (MDA) and 4-hydroxynonanal (4HNE), the two major end products of lipid peroxidation, in all the three brain regions i.e. fore-, mid- and hind-brain. The levels of hydrogen peroxide (H2O2) were also increased in all the three brain regions when compared with control. CPF and MPT exposure caused decrease in the levels of reduced glutathione (GSH) and increase in the levels of oxidized glutathione (GSSG) in all the three brain regions. The increase in the levels of MDA, 4HNE, H2O2 and GSSG was less pronounced when CPF or MPT was given to the rats fed with a mixture of vitamin A, E and C. The present findings clearly show that oral intake of a mixture of vitamin A, E and C protects the rats from MPT or CPF induced oxidative stress and suggest that this treatment alleviates the toxicity of these pesticides to a greater extent. [Copyright &y& Elsevier]

Abstract: Organophosphate pesticides are among the most widely used synthetic chemicals for controlling a wide variety of pests. Chlorpyrifos (CPF) is among the leading organophosphate (OP) pesticides used extensively throughout the world including India. Besides being potent anticholinesterase compounds, these OP pesticides are known to generate oxidative stress. Present study was carried out to see the level of reactive oxygen species (ROS), hydrogen peroxide (H2O2), nitrate (NO3 −) and nitrite (NO2 −) in different parts of rat brain and liver after giving different doses of CPF intramuscularly for 3days or for 1month. Results of the present study clearly revealed that levels of H2O2, NO3 − and NO2 − were increased significantly in all the three parts of rat brain i.e., fore-, mid- and hind-brain as well as in liver of rats given for 3days or 1month due to exposure of different doses of CPF. The study clearly demonstrated that CPF generated oxidative stress in all the three brain regions as well as liver of rats and the ROS were accumulated. Accumulation of ROS in all the regions of brain and other tissues may disturb the normal physiological functions aggravating the toxicity symptoms of CPF. [Copyright &y& Elsevier]

Abstract: Chlorpyrifos (O,O′-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) exposure in rats causes elevation in the levels of thiobarbituric acid reactive substances (TBARS) and inhibition of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT), and glucose-6-phosphate dehydrogenase (G6PDH) activities in the liver, kidney, spleen, and brain of rats. The sublethal exposure of CPF also causes decrease in the levels of reduced glutathione (GSH) and consequent increase in oxidized glutathione (GSSG) levels, resulting in a significant decrease in GSH/GSSG ratio in all the rat tissues tested. These results clearly indicate that CPF exposure causes oxidative stress in rat tissues. However, CPF exposure to rats fed with antioxidant vitamins (vitamin A, E, and C) for 1 month, prevented derangement of these antioxidant parameters. The accumulation of TBARS was also not seen in tissues of rats fed with antioxidant vitamins on CPF exposure. AChE activity, which is sensitive to OP pesticides, was also not significantly inhibited in these rats on CPF exposure. The present findings clearly show that oral intake of a mixture of vitamin A, E, and C, protects the rats from CPF induced oxidative stress and suggesting that this treatment alleviates the toxicity of this pesticide. [Copyright &y& Elsevier]