ABSTRACT
Little information is apparently available regarding the nephrotoxic effects induced by pesticides. The aim of this study was to examine the influence of low doses of methyl parathion (MP) on the structure and function of the kidney of male Wistar rats. A corn oil (vehicle) was administered to control rats, whereas treated rats received MP at 0.56 mg/kg orally (1/25 of LD50), every third day, for 8 weeks. At the end of each week following MP exposure, creatinine and glucose levels were measured in plasma, while glucose, inorganic phosphate, total proteins, albumin, and activity of γ-glutamyltranspeptidase (GGT) were determined in urine. Kidney histological study was also performed. Compared with control rats, MP significantly increased plasma glucose and creatinine levels accompanied by decreased urinary flow rate and elevated urinary excretion rates of glucose, phosphate, and albumin. Further, the activity of GGT in urine was increased significantly. The proximal cells exhibited cytoplasmic vacuolization, positive periodic acid Schiff inclusions, and brush border edge loss after 2 or 4 weeks following MP treatment. Finally, renal cortex samples were obtained at 2, 4, 6, and 8 weeks of MP treatment, and the concentrations of reduced glutathione (GSH) and glutathione peroxidase (GPx) activity were measured. The mRNA expression levels of BAX and tumor necrosis factor-α (TNF-α) were also determined (RT-PCR). MP significantly decreased renal GSH levels, increased GPx activity, as well as downregulated the mRNA expression of TNF-α and BAX. Densitometry analysis showed a significant reduction in TNF-α and BAX mRNA expression levels at 2 and 4 weeks following MP treatment. Low doses of MP produced structural and functional damage to the proximal tubules of male rat kidney.
