Sulforaphane protects granulosa cells against oxidative stress via activation of NRF2-ARE pathway

Sulforaphane (SFN) has been considered as an indirect antioxidant and potential inducer of the Nrf2-ARE pathway. This study was conducted to investigate the protective role of SFN against oxidative stress in bovine granulosa cells (GCs). GCs were collected from antral follicles (4-8mm) and cultured according to the experimental design where group 1=control, group 2=treated with SFN, group 3=treated with hydrogen peroxide (H2O2), group 4=pretreated with SFN and then with H2O2 (protective) and group 5=treated with H2O2 followed by SFN treatment (rescuing). Results showed that SFN pretreatment significantly increases cell viability and reduces cytotoxicity in GCs under oxidative stress. Following H2O2 exposure, expression of NRF2 was found to be significantly increased (p<0.05) in SFN-pretreated cells, while no significant differences were observed between group 3 and group 5, although the expression was significantly increased compared to the control group. Moreover, the relative abundance of the NRF2 downstream target antioxidant genes (CAT, PRDX1, SOD1 and TXN1) were higher (fold change ranged from 7 to 14, p<0.05) in sulforaphane pretreated GCs. Low level of ROS and lipid accumulation and higher mitochondrial activity were observed in GCs pretreated with SFN, whereas no such changes were observed in GCs treated with SFN after exposure to oxidative stress (group 5). Thus, we suggest that SFN pretreatment effectively protects GCs against oxidative damage through the activation of the NRF2-ARE pathway, whereas addition of SFN during oxidative insult failed to rescue GCs.