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

Background: 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. Objective: The purpose of this study was to determine the effects of diazinon on oxidant-antioxidant system in rat liver. Methods: 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. Findings: 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). Conclusion: 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.