Objective: To investigate the effect of 17-beta estradiol (E(2))on the expression of receptor activator of nuclear factor kappaB ligand(RANKL) and osteoprotegerin(OPG) in human periodontal ligament cells( hPDLCs) during their osteogenic differentiation.
Methods: hPDLCs of passage four were treated with 0.1% absolute ethyl alcohol (control), 10(-10) mol/L(physiological dose) or 10(-7) mol/L(high dose) E(2) in DMEM supplemented with 10% FBS, 10 mmol/L beta-glycerophosphate and 5 microg/mL ascorbic acid for 24 hours, 48 hours and 72 hours. Levels of RANKL and OPG mRNA were detected with real-time quantitative RT-PCR.
Results: High dose E(2) induced a time-dependent decrease of RANKL mRNA and expression levels were 31.0%, 23.6% and 15.4% of the controls at 24 h, 48 h and 72 h respectively while expression levels with physiological dose E(2) were 28.4%, 87.3% and 22.6% of the controls respectively. On the other hand, E(2) increased OPG mRNA expression levels of hPDLCs which reached the maximum at 72 h with physiological dose E(2), 210.1% of the controls and with high dose E(2), 171.3% of the controls.
Conclusion: These results suggest that estrogen may exert anti-resorptive effects on alveolar bone by regulating the expression of RANKL and OPG in hPDLCs during their osteogenic differentiation.