Problem: Nuclear factor kappa B (NF-κB) is one candidate transcriptional modulator, which might regulate many kinds of molecules that play sequential roles at implantation in the endometrium. However, temporal and spatial activation of NF-κB at implantation window is unknown.
Methods: Activation of NF-κB in the mouse uterus was determined by electrophoretic mobility shift assays. Localization of p50 and p65, components of NF-κB, was analyzed by immunohistochemistry.
Results: NF-κB was activated in the proestrus and estrus phases in non-pregnant uterus. In the pregnant uterus, NF-κB was activated after day 1.5 post-coitum, and the activation continued during implantation period. The immunoreactivities of p50 and p65 were mainly localized in endometrial epithelium, and were weaker in endometrial stroma cells.
Conclusion: NF-κB activity is dynamically regulated during the sexual cycle as well as during the implantation period in the endometrium, where the biochemical interaction between mother and conceptus first occurs.