Nonylphenol, an environmental contaminant, has been shown to induce reproductive abnormalities in male rats. The nature and mechanism of action of
nonylphenol on the epididymal sperm has not been elucidated. In the present study we have sought to investigate whether administration of
nonylphenol induces oxidative stress in rat epididymal sperm.
Nonylphenol was administered orally to male rats at 1, 10 and 100 microg/kg
body weight per day for 45 days. Twenty-four hours after the last treatment, rats were weighed and killed using anaesthetic
ether. The
body weight of the animals treated with
nonylphenol did not show any significant change. The weights of the testes and epididymides decreased significantly whereas the weights of seminal vesicles and ventral prostate remained unchanged at all doses of
nonylphenol in treated rats. Epididymal sperm were collected by cutting the epididymides into small pieces in Ham's F-12 medium at 32 degrees C. Administration of
nonylphenol decreased the epididymal sperm counts in a dose-dependent manner. The activities of
antioxidant enzymes superoxide dismutase,
catalase,
glutathione reductase and
glutathione peroxidase decreased significantly while the levels of H(2)O(2) generation and lipid peroxidation increased significantly in the animals treated with
nonylphenol when expressed in terms of milligram
protein and milligram
DNA. The activity of
alpha-glucosidase, a negative control against
antioxidant enzymes, in the sperm of
nonylphenol-treated rats did not show any significant change at any of the doses. The results suggest that graded doses of
nonylphenol elicit depletion of
antioxidant defence system in sperm, indicating
nonylphenol-induced oxidative stress in the epididymal sperm of rats.