Peroxiredoxin 2 (PRDX2) has been known to act as an antioxidant enzyme whose main function is H(2)O(2) reduction in cells. We aimed to study the expression patterns of PRDX2 in mouse ovaries and explore the function of this protein in apoptosis of granulosa cells (GCs). We found that the expression of the PRDX2 protein in atretic follicle GCs was markedly higher than in healthy follicle GCs. In vitro, the transfection of siRNA targeting the Prdx2 gene inhibited the proliferation and induced the apoptosis of primary cultured GCs. Furthermore, suppression of PRDX2 resulted in the augmentation of endogenous H(2)O(2), and the ability to eliminate the exogenous H(2)O(2) was attenuated. The expression of PRDX2 and nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB), whose activity was inhibited by binding to IKB, increased in GCs treated with various concentrations of H(2)O(2) for 30 min. However, no significant change in cytoplasmic IKB expression was observed. At 2 h after treatment with H(2)O(2), nuclear NFKB expression level was reduced, cytoplasmic IKB expression was increased, and PRDX2 expression was unchanged. Silencing of the Prdx2 gene caused early changes in NFKB and IKB expression in the primary cultured GCs compared to that in control cells. Taken together, these data suggest that PRDX2 plays an important role in inhibiting apoptosis in GCs and that PRDX2 actions may be related to the expression of NFKB and IKB.