INHIBITION BY ESTRADIOL OF OXIDATIVE STRESS-INDUCED APOPTOSIS IN PIG OVARIAN TISSUES

Oxidative stress-induced apoptotic cell death has been implicated in t he mechanisms of corpus luteum regression and follicular atresia. The objective of this investigation was to determine whether the antioxida nt, oestradiol influenced apoptosis in pig luteal and follicular tissu es exposed in vitro to hydrogen peroxide. Immunolocalization of fragme nted DNA (a biochemical marker of apoptosis) in large steroidogenic lu teal and granulosa cells was inhibited by oestradiol. Protection again st apoptosis required relatively high concentrations of oestradiol (gr eater than or equal to 40 pg ml(-1) incubation media) and was largely unmitigated by actinomycin D (suggesting a predominantly receptor-inde pendent nongenomic mode of action). Ovarian cells were not protected b y other (nonaromatizable) steroid hormones. It is suggested that oestr adiol functions at the ovary as a reactive oxygen scavenger during pre gnancy-mediated luteal rescue and folliculogenesis.