Comparison of the effects of diazinon and paraoxon on the antioxidant system of rat lung

Diazinon and paraoxon are the most widely used organophosphates (OPs) in agriculture. Some Ops can increase production of free radicals and induce disturbance in body antioxidant system. The aim of this study was to investigate the effects of diazinon and paraoxon on antioxidant system in rat lung. In this experimental study, forty-nine male Wistar rats were randomly divided into seven groups. Control group received corn oil (a solvent for diazinon and paraxon) and six experimental groups received intraperitoneal injection of different doses of diazinon (30, 50 and 100 mg/kg) and paraoxon (0.3, 0.7, 1 mg/kg). We used ether for anesthesia. Twenty-four hours after injections, we removed lung tissue of the rats. Then superoxide dismutase (SOD), catalase (CAT), glutathione S- transferase (GST) and lactate dehydrogenase (LDH) activities and glutathione (GSH) and malondialdehyde (MDA) levels were determined by biochemical methods. The data were analyzed by means of ANOVA and Tukey test. Activities of SOD, CAT and GST were significantly increased at doses of higher than 0.3 mg/kg of paraoxon and also when diazinon used at the dose of 100 mg/kg. LDH activity and MDA level increased and GSH level decreased when we gave higher doses of paraoxon to the rats. Diazinon and paraoxon induced the production of free radicals and oxidative stress in a dose-dependent manner. The enhanced activity of antioxidant enzymes and lipid peroxidation level and depleted GSH content indicated failure of antioxidant system to combat free radicals and oxidative tissue injury. Paraoxon had more toxic effect on antioxidant system in comparison to diazinon.