Expression of nuclear factor-kappaB in mouse uterus during peri-implantation.

To investigate the expression of the subunit p65 of NF-kappaB and inhibitor kappa B alpha (IkappaBalpha) in mouse uterus during peri-implantation, thereby investigating whether transient activation of nuclear factor-kappaB (NF-kappaB) takes place during embryo implantation in mice. Immunohistochemical technique was used to examine the expression and localization of p65 in endometrium or deciduas, and Western blot analysis was employed to detect the levels of IkappaBalpha protein in mouse endometrium or deciduas. P65 protein was detected in stromal cells, epithelial cells of endometrium as well as in myometrium. Staining was predominately seen in the cytoplasm of the cells. Staining intensity for p65 was stronger in the epithelial compartment than the stromal compartment and myometrium. Staining intensity increased slightly during pregnancy, and it reached a high level on pregnancy day 5 and day 8. In contrast to p65, the level of IkappaBalpha protein was lowest on pregnancy day 5 in all groups. Our results suggested that NF-kappaB may regulate embryo implantation by its transient activation in mice.