ABSTRACT
Objective To investigate the effects of 17?-estradiol (E2) on the gene expression of typeⅠA bone morphogenetic protein receptor (BMPR-ⅠA) and core-binding factor alpha 1 (Cbf?1) in rat bone marrow stromal cells exposed to the differentiation medium and to elucidate the effects of E2 on osteoblastogenesis. Methods Adherent bone marrow stromal cells were cultured in differentiation medium containing DEX (10 -7 mol/L), 1,25-(OH)2D3 (10 -9 mol/L) and different concentrations of E2. Effects of different concentrations of E2 on the gene expression of BMPR-ⅠA and Cbf?1 was quantified by RT-PCR based on the comparison with an internal reference, ?-actin expression, and identified by Northern blotting. Alkaline phosphatase (ALP) activity of cells was detected. Contents of type Ⅰ collagen were determined by Van Gieson staining. Results E2 could evidently inhibit the expression of BMPR-ⅠA and Cbf?1 mRNA during the differentiation process of bone marrow stromal cells into osteoblasts in a dose-dependent manner. These were confirmed by Northern blotting. The ALP activity increased in a concentration-dependent manner, but the amount of type Ⅰ collagen decreased in a concentration-dependent manner. Conclusion E2 can significantly inhibit the gene expression of BMPR-ⅠA and Cbf?1 in bone marrow stromal cells and inhibit osteoblastogenesis in vitro.