Reproduction Abstracts

Introduction: A sucessful implantation depends on the exquisite coordination between embryo and maternal uterus. N-myc downregulated gene 2 (NDRG2) belongs to the NDRG gene family, a new class of Myc-repressed genes, and possesses tumor suppression function. Given the similarities between embryo implantation and the growth of cancer cell, the present study was undertaken to examine the expression and regulation of NDRG2 during peri-implantation period.

Materials and methods: The expression pattern of NDRG protein and mRNA during peri-implantation period in mice were determined by immmunohistochemical and RT-PCR analyses. The delayed implantation and artificial decidualization mouse models, as well as the treatment of E₂ or/and P4, were performed to observe the regulation of uterine NDRG2 expression.

Results and discussion: No detectable NDRG2 protein signal was found in uterus on days 1–3 of pregnancy, and a faint possitive signal could be observed in stroma on day 4 of pregnancy. NDRG2 protein was detected in the secondary decidual zone on days 5 and 8 of pregnancy, and the expression level in decidual zone was markedly increased. The expression of NDRG2 mRNA was detected from day 1–8 of pregnancy, and its expression level at the implantation site was significantly higher compared to the inter-implantation site. Under in vivo artificial decidualization, NDRG2 protein expression was significantly increased compared with control. Compared with the progesterone-primed delayed implantation uterus, an up-regulated expression of NDRG2 protein was detected in estrogen-activated implantation uterus. In ovariectomized mouse uterus, estrogen and progesterone could induce the expression of NDRG2 protein. These results suggest that NDRG2 might play an important role during mouse embryo implantation, and estrogen and progesterone could regulate the expression of NDRG2 gene.