Abstract
The present study was intended to evaluate the effect of zinc oxide nanoparticles (ZnO-NPs) on chromium (Cr VI)-induced reproductive toxicity in male rats. Forty adult male albino rats were randomly divided into four equal groups (10 rats each): control group, chromium (Cr VI) group: potassium dichromate (K2Cr2O7) given orally at dose 10 mg/kg bwt/day (equals to 1/10 of LD50) (five days a week), Cr VI + ZnO-NPs group: rats received 10 mg/kg bwt/day (five days a week K2Cr2O7 orally and injected intraperitoneally (IP) by ZnO-NPs-saline solution at dose 5 mg/kg bwt/ day (three days a week). ZnO-NPs-group: ZnO-NPs- saline solution (IP) at dose 5 mg/kg bwt/ day (three days a week). Ten weeks post-treatment, serum testosterone values were significantly decreased in the Cr (VI) and Cr (VI) + ZnO-NPs-treated rats, sperm counts and significant increase in sperm abnormalities. No significant alteration in testicular malondialdehyde and superoxide dismutase levels among treated groups all over the experiment compared to control. However, reduced glutathione concentrations in testes were significantly decreased in Cr (VI) + ZnO-NPs and ZnO-NPs groups at ten weeks post-treatment. Cr (VI) group showed marked histopathological alterations and to lesser extent Cr (VI) + ZnO-NPs group that were time dependent. . ZnO-NPs group showed significant testicular lesions, particularly after ten weeks post-treatment. It could be concluded that Cr (VI) intoxication induced damaging effects on male reproductive functions that were time dependent. ZnO-NPs partially improved these effects. But, its use for longer period has no valuable effect on Cr (VI)-induced toxicity.

Key words: zinc oxide, nanoparticles, pathology, testes, rat