Ovarian expression of p53 and p21 apoptosis regulators in gamma-irradiated mice

Ovarian follicular degeneration is accelerated by gamma-radiation. To investigate the precise radiation-induced cellular and molecular biological changes in the ovary, prepubertal mice were whole-body irradiated with 6.94 Gy, which is the 30% of the lethal dose of gamma-radiation using a (60)Co source. At 0, 3, 6, 12, and 24 hr after irradiation, ovarian expression of p53 and p21 mRNA and protein were analyzed by reverse-transcription polymerase chain reaction and immunoblotting, respectively. Immunohistochemical localization of p53 and p21 antigens was also carried out. Immunoreactive p53 and p21 were expressed in the nuclei of granulosa cells, but were not detected on the theca. In control mouse ovaries, p21 was weakly expressed on granulosa but not on the theca cells. In gamma-irradiated mouse ovaries, however, immunoreactive p21 proteins were detected in the nuclei of follicular granulosa cells. After irradiation expression of p53 and p21 mRNA and protein was significantly increased compared to beta-actin. Taken together, these observations suggest that p53 and p21 are actively involved in gamma-radiation-induced follicular degeneration in the prepubertal mouse ovary.