Comparison of the Actions of 17β-estradiol and Progesterone on the Expression of Osteoprotegerin in Normal Human Osteoblast-Like Cells

Objective:To compare the action between 17β-estradiol (17β-E 2) and progesterone(P)on OPG expression in cultured normal human osteoblast-like cells (hOB).Methods:OPG mRNA levels were determined by Northern blot analysis,and OPG protein concentrations in conditioned media were determined by ELISA.Results:After 12-48 hours of treatment,E 2 at 10 -8M increased OPG mRNA levels in cultures of hOB(P0.05),the expression of OPG mRNA and the production of OPG protein by hOB show a dose-dependent model(P0.05).(10 -10M E 2 group produced 1.27±0.26ng/ml,10 -9M E 2 group produced 2.34±0.35ng/ml,10 -8M E 2 group produced 3.62±0.23ng/ml,and compared with control which produced 0.64±0.14ng/ml,P0.01).After 12-48 hours of treatment,E 2 at 10 -8M increased OPG protein levels in cultures of hOB (12h group produced 1.30±0.30ng/ml,24h group produced 3.07±0.14ng/ml,48h group produced 3.50±0.33ng/ml,and compared with control which produced 0.62±0.12ng/ml,P0.01).However,progesterone at 10 -8M had no effects on OPG mRNA levels and protein production in cultures of hOB (all P0.05).Conclusion:The stduy suggest that the different regulation of OPG production in osteoblasts by E 2 and progesterone may contribute to the mechanisms by which estrogen or progestins exerts its different action on bone resorption.