[Evaluation of oxidative stress biomarkers of rat liver exposed to acute doses of diazinon]

Diazinon is one of the most important organophosphates [OPs] widely used in agriculture. Some OPs have the potential to produce free radicals and induce disturbance in body antioxidant systems. The purpose of this study was to determine the effects of diazinon on oxidant-antioxidant system in rat liver. This experimental study was carried out at Baqiyatallah University of Medical Sciences in 2010. A total of 28 male Wistar rats [200-250 g body wt.] were randomly divided into four groups including: sham [received corn oil as diazinon solvent] and three diazinon groups receiving different single doses of this substance [30, 50, and 100 mg/kg] through intraperitoneal route. Twenty four hours after injection, the animals were ether anesthetized and liver tissue removed. Following liver tissue hemogenation, the activity of superoxide dismutase [SOD], catalase [CAT], glutathione S-transferase [GST], and lactate dehydrogenase [LDH] as well as the glutathione [GSH] and malondialdehyde [MDA] levels were determined by biochemical methods. The data were statistically analyzed using the analysis of variance followed by post hoc analysis using Tukey tests. While at concentrations higher than 30 mg/kg diazinon, increased activities of SOD, CAT, and GST with higher level of MDA were observed, the GSH level was significantly decreased when compared with the sham. Also, an increased LDH activity at dose of 100 mg/kg was seen [P<0.01]. Diazinon probably induces the production of free radicals and oxidative stress in a dose-dependent manner. Enhanced activity of antioxidant enzymes with depleted GSH content is indicative of oxidative tissue injury and increased MDA level is suggestive of damage occurring in liver membranes

[Effect of paraoxon on antioxidant system and lipid peroxidation in liver of rat]

The toxic effects of some organophosphate pesticides [Ops] which are capable to produce free radicals and induce disturbance in body antioxidant systems. Paraoxon is an OP that is the active form parathion. To evaluate the effect of paraoxon on liver antioxidant system of rat. Wister rats were randomly divided into four groups including: control [paraoxon solvent], and three groups receiving different doses of paraoxon [0.3, 0.7 and 1 mg/kg] by intraperitoneal injection. Animal were anesthetized and liver tissue removed 24 hours after injection. After hemogenation of liver tissue Superoxide Dismutase [SOD] and Catalase [CAT], Lactate Dehydrogenese [LDH] and Glutathione S- Transferase [GST] activities, Glutathione [GSH] and malondialdehyde [MDA] levels were determined by biochemical methods. Paraoxon increased CAT, LDH and SOD activities and MDA level at doses higher than 0.3 mg/kg, while GSH level was decreased significantly, as compare with the control group. GST activity was increased significantly at 0.3 and 0.7 mg/kg concentration [P<0.05], but at 1 mg/kg concentration was decreased as compare with the control group. Probably Paraoxon induced the production of free radicals and oxidative stress in a dose- dependent manner. The enhanced activity of antioxidant enzymes of liver is due to increase the detoxification capacity. Decrease of tissue GSH content indicatives of oxidative tissue injury and the increase of MDA level indicatives per oxidation that occurs in membranes of liver