Effects of dimethoate application on biochemical and hematological parameters and investigation of DNA damage and endocrine disruption potential

Hematological, biochemical and genotoxic effects together with neurotoxicity and endocrine disruption potential of dimethoate in Oncorhynchus mykiss tissues were investigated in this research. For this reason, adult O. mykiss were exposed to 0.0735 mg/L, 0.3675 mg/L and 0.7350 mg/L of pesticide concentrations for 5, 15 and 30 days. The autoanalyzer for hematologic analyses, spectrophotometric methods to determine oxidative stress parameters and comet assay for DNA damage were used. Determined decrease in erythrocyte and leucocyte numbers, hemoglobin and hematocrit, MCV and MCH especially after prolonged exposure refers to occurrence of microcytic hypochromic anemia. Hyperglycemic and hypoproteinemic conditions detected as response to compensate high metabolic demand caused by dimethoate stress are supported by behavioral changes observed in O. mykiss. Inhibition rate of 45-94% in AChE specific activity in liver and brain tissues is sign of acetylcholine accumulation and impairment in cholinergic transmission in tissues. It is assumed that observed behavioral abnormalities are caused by dimethoate induced neurotoxicity. Dimethoate did not show anti-androgenic effect in O. mykiss, however it introduced endocrine disrupting effect by changing feedback mechanism on H-P axis and functioning as estrogen mimic as confirmed by altering 17ß-estradiol levels. Duration- and concentration-dependant increase in enzyme activities of aminotransferases of ALT and AST is revealed that dimethoate exerts its toxic action directly on liver tissue and impairs cell membrane permeability. Biphasic response obtained in antioxidant enzyme activities of liver and brain tissues of O. mykiss and increase in lipid peroxidation are elucidated that antioxidant defense was not effective enough in order to inactivate reactive species and dimethoate application resulted in oxidative stress. In addition, it was determined that brain tissue is more sensitive than liver to oxidative stress because of low antioxidant capacity. Detecting high level of DNA damage in pesticide exposed groups over control by comet assay clearly verified genotoxic action of dimethoate. It is concluded with this investigation that analysing different toxicity biomarkers together contributes to obtain more meaningful results in evaluating toxic profile of chemical and dimethoate is highly toxic when responses observed in O. mykiss at sublethal concentration were taken into account.