Time-dependent effects of pentabrominated diphenyl ethers on gonadal hormone and genital system histology in male rats

The aim of this study was to examine the effects of pentabrominated diphenyl ethers (PBDE) on gonadal hormone levels and histology in male rats. Rats in treatment groups were orally gavaged with PBDE-99 at a dose of 120 mg?kg^?1 for 5, 15, 30, or 45 days, while controls received equal volume of corn oil. In the treated groups, changes were not found on day 5. On day 15, testicular weight increased, serum levels of estradiol (E₂) decreased, proliferation cell nuclear antigen (PCNA) positive expression was reduced, and sperms within the seminiferous tubules were damaged. On day 30, testicular weight was further increased, serum levels of testosterone (T) and E₂ decreased, PCNA positive expression was further reduced, some primary spermatocytes cells did not express, and seminiferous epithelium was degenerated. At 45 days, testicular weight decreased, levels of T, E₂ concentrations were lower, histopathologic examination revealed severe degeneration of seminiferous epithelium, and only a part of spermatogonial cells were expressed. The earliest alterations occurred at 15 days. PBDE-99 produced time-dependent reduction of gonadal hormone levels and degeneration of gonadal system histology.