Total Flavonoid Fraction of Rhizoma Drynaria Improves Bone Properties in Ovariectomized Mice and Exerts Estrogen-Like Activities in Rat Osteoblast-Like (UMR-106) Cells   全文下載

Total Flavonoid Fraction of Rhizoma Drynaria Improves Bone Properties in Ovariectomized Mice and Exerts Estrogen-Like Activities in Rat Osteoblast-Like (UMR-106) Cells

The present study was designed to determine if RD total flavonoids (RDTF) could exert estrogen-like protective actions on bone. Young C57/BL6J mice were ovariectomized (OVX) and treated orally with RDTF (0.087, 0.173 or 0.346 mg/g/day), 17β-estradiol (2μg/g/day) or its vehicle for 6 weeks. Bone mineral densities (BMD) was measured by peripheral quantitative computed tomography (pQCT). Rat osteoblast-like UMR-106 cells were co-incubated with ER antagonist ICI 182, 780 to determine if the effects of RDTF on osteoblastic functions were ER-dependent. The functional transactivation of ER-α and ER-β as well as ER-αphosphorylation by RDTF were also studied. RDTF increased trabecular-rich BMD at distal femur and lumbar spine in OVX mice. 0.173 mg/g/day was most effective in improving bone properties in OVX mice. The stimulatory effects of RDTF on osteoblastic functions could be abolished by co-incubation with ICI 182, 780 in UMR-106 cells. Transient transfection study indicated that RDTF dose-dependently stimulated ERE-dependent luciferase activity in UMR-106 cells via ER-α and ER-β. Moreover, 0.2 μg/mL of RDTF significantly induced ER-α phosphorylation at serine 118 in UMR-106 cells.