Effects of malathion exposure on glucose tolerance test in diabetic rats; emphasis on oxidative stressand blood concentration of malathion by gas chromatography mass spectrometry

Malathion is one of the widely used broad-spectrum organophosphate insecticides (OPI) in Iran. Malathion affects carbohydrate metabolism, causes hyperglycemia and increases the risk of diabetes. The present study was undertaken to investigate the potential of malathion to exacerbate diabetes-induced oxidative stress and impairment in blood glucose level and glucose tolerance in a sub-acute study. Malathion concentration in blood was analyzed with gas chromatography mass spectrometry (GC-MS) after sample preparation of blood samples based on magnetic Fe3O4-supported graphene oxide (Fe3O4@ GO) nanoparticles. Type 1 diabetes was experimentally induced by intraperitoneal administration of streptozocin (65 mg kg-1). Diabetic and non-diabetic rats were treated with malathion at the dose of 150 mg kg-1day-1 or 0.5-4.0 mg L-1 in blood for 4 weeks. Fasting blood glucose was measured every week. At the end of the study, blood samples were investigated for markers of oxidative stress. Exposure to multiple doses of malathion decreased the total antioxidant capacity of plasma and the activity of catalase and superoxide dismutase enzymes in diabetic rats. Blood glucose and glucose tolerance test (GTT) and oxidative damages did not change significantly in diabetic rats exposed to malathion. However, malathion concentration in blood caused to increase GTT in malathion-treated non-diabetic rats. Taking together, our findings provide evidence that daily exposure to malathion for 4 weeks tends to exacerbate the decrease in blood antioxidant status and protein carbonylation in diabetic rats.