Toxicological effects of 3-methyl-4-nitrophenol on mouse ovarian and testicular cell proliferation, apoptosis and oocyte maturation

The aim of the present study was to reveal the effects of 3-methyl-4-nitrophenol (PNMC) on mouse gonadal cell proliferation and apoptosis. Immature female and male mice were intramuscularly injected with 100 mg/kg PNMC or vehicle every five days. One-month later, ovarian rather than testicular weights were significantly decreased. The positive terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling staining was enhanced in both testicular seminiferous epithelium and ovarian corpus luteum. Further study in ovaries showed that PNMC treatment increased the protein expressions of PCNA, p21 and p27, and decreased the expression of Cyclin D2. Whereas PNMC had no significantly influence on those protein expressions in testes. In addition, we demonstrated that 100 nM PNMC significantly suppressed mouse oocyte meiotic resumption and cumulus cell expansion in vitro. These findings suggest that the reproductive toxicities of PNMC involve affecting the processes of gonadal cell apoptosis and proliferation.