[Response of brain antioxidant defense system to acute doses of paraxaon in male rats]

ABSTRACT

The toxic effects of some Organophosphates [Ops] are not limited to inhibition of cholinesterase, they are capable to produce free radicals and induce disturbance in body antioxidant systems. Paraoxon is an OP, which is the active form of parathion. The aim of this study was to investigate the effects of paraxaon on oxidant-antioxidant system in rat brain tissue. Wistar rats were randomly divided into four groups [n=7] as followed control [corn oil as paraoxon solvent] and three of groups of paraxaon receiving different doses [0.3, 0.7 and 1 mg/kg] by intraperitoneal injection. 24 hours after injection, animal to ether anesthesia and brain tissue removed. After brain tissue hemogenation, superoxide dismutase [SOD] and catalase [CAT], lactate dehydrogenase [LDH] and glutathione S-transferase [GST] activities, glutathione [GSH] and malondialdehyde [MDA] levels were determined by biochemical methods. At doses higher than 0.3 mg/kg paraoxon, the enhanced activities of kidney SOD, CAT and GST and LDH activity [>/= 0.3 mg/kg] were significantly increased, comparing with the control, while GSH level was significantly decreased. There were no significant changes observed in MDA level. The results suggest that paraoxon induces the production of free radicals and oxidative stress in a dose- dependent manner. The enhanced activity of antioxidant enzymes in brain of rats probably as a function of the increased detoxification capacity. Depletion of tissue GSH is a prime factor, which can impair the cell's defense against the toxic actions of free radicals