Although atresia of bovine follicles is associated with apoptosis of granulosa cells, the signals initiating this cell death have not been resolved. NF-κB has been implicated as an important regulator of genes controlling apoptosis, and previous studies indicate that estradiol may modulate NF-κB activation. We hypothesized that estradiol activates NF-κB, and thus, inhibits apoptosis in granulosa cells of dominant follicles. Dominant follicles were collected on Days 4, 6, and 8 of the first follicular wave following ovulation and assayed for NF-κB activity. Concentrations of estradiol in follicular fluid decreased on Day 6 compared to Day 4 of the wave. NF-κB activity in granulosa cells was lower on Day 8 compared to Days 4 and 6. In vitro, NF-κB activity and minimal incidence of apoptosis (<4%), as measured by Annexin V and TUNEL assays, were associated with production of estradiol. However, inhibition of NF-κB in vitro led to a suppression of apoptosis. These results indicate that follicular NF-κB activation is associated with estradiol production. However, whether NF-κB is playing a pro- or anti-apoptotic role in granulosa cells of the dominant bovine follicle remains to be elucidated.
All Science Journal Classification (ASJC) codes
- Molecular Biology