WHICH EXPOSURE PERIOD TO SELENIUM IS MORE PROTECTIVE AGAINST HEPATO-RENAL TOXICITY OF METHOMYL IN MALE RATS?

This study was undertaken to investigate selenium (Se) as a protective agent against the effects of methomyl (Me) induced oxidative stress in liver and kidney of male rats. Rats were treated orally with the Acceptable Daily Intake (ADI) dose of methomyl for a period extended up to 14 days. Selenium was administered before, during and after methomyl dosing. A total of 54 rats were segregated into nine groups (G) each of six animals; as follows: G1:(Control group; received drinking water for 14d ); G2: (Se for 14d, every 48h); G3: ( Me for 7d); G4: (Me for 7d + Se for 3d); G5: (Me for 7d + Se for 7d); G6: (Me + Se for 7d); G7: (Se for 3d + Me for 7d); G8: (Se for 7d + Me for 7d); and G9: (Me for 7d + recovery for 7d). The results revealed that administration of methomyl alone (e.g., G3 & G9) can induce hepato and renal dysfunction represented by body weight gain decrease, elevation of aminotransferases (AST & ALT) and ALP activities, and decreasing of BuChE activity. The insecticide decreased concentration of urea and increased creatinine concentration. The antioxidant enzymes, SOD and TAC were decreased, while MDA increased. On the other hand, methomyl induced noticeable impairment in the histopathological structure of liver and kidneys. Co-administration of selenium in conjunction with methomyl improved all the above mentioned parameters, but to varying degrees, based on duration and timing of selenium administration. The best improvement was obtained from the treatment of G5 in which methomyl was given for 7 days followed by selenium for other 7 days (Me for 7d + Se for 7d). It was concluded that methomyl has the capability to induce oxidative damage as evidenced by increasing LPO and perturbations in various antioxidant enzymes. Supplementation of selenium in conjunction with methomyl minimized the insecticide's toxicity. The best improvement was obtained from giving selenium after methomyl for an equal period. Such results may shed light to the issue of interaction between the times of antioxidant administration and the pesticide exposure.