Oxidative stress in mature rat testis and its developmental changes

Active oxygen causes various problems including male infertility through the oxidation of DNA, proteins, and lipids. In the present study, we examined the immunohistochemical localization of molecules involved in oxidative stress including 8-hydroxy-2-deoxyguanosine (8-OHdG), superoxide dismutase (SOD), and protein disulfide isomerase (PDI) in mature and developing rat testes. In mature rat testes, 8-OHdG was detected in leptotene, zygotene, and early pachytene spermatocytes, while its expression was weak in late pachytene stage spermatocytes. On the other hand, SOD was detected in late pachytene spermatocytes but not in early pachytene and former spermatocytes, suggesting the efficient removal of active oxygen by SOD in late pachytene spermatocytes. In developing rat testes, 8-OHdG expression peaked at 4 weeks when spermatocytes started to differentiate to the late pachytene stage, while SOD started to be expressed at 4 weeks after birth. These findings suggest that the defense system against oxidative stress by SOD is developed in late pachytene stage spermatocytes at 4 weeks after birth. The present findings aid our understanding of the defensive mechanism against oxidative stress in developing and mature testes.