Sertoli cells play an essential role in the development of a functional testis. ROS (reactive oxygen species) are normally produced by the developing testicular cells and may be dangerous to spermatogenesis. The aim of this study was to investigate the developmental expression of genes involved in antioxidant defense as well as in the DNA damage response in rat Sertoli cells. As revealed by quantitative RT-PCR analysis, the expression pattern of the antioxidant enzymes GST (glutathione-S-transferase), CAT (catalase) and SOD (superoxide dismutase) showed a progressive decrease from birth to puberty. The expression level of the oncosuppressor p53 revealed a net reduction as well. We next focused on PARP-1 [poly(ADP-ribose) polymerase-1], a ‘guardian of the genome’ that combats stress conditions. At both the mRNA and protein level, PARP-1 expression was low at the early stage of development and increased later on. Maximal PARP-1 expression was preceded by a rise in the transcript level for MTs (metallothioneins), which provide zinc to zinc-dependent enzymes and proteins, including PARP-1. Our results showed an increased expression of PARP-1 during Sertoli cell development, together with a decrease in the expression of antioxidant enzymes. In conclusion, a role of PARP-1 in protecting the testicular differentiation is suggested.