Inhibitory Effects of on Osteoclast Differentiation and Bone Resorption

Purpose: The first purpose of this study is to find out whether the water extract of Rehmanniae Radix Preparat(RRP), Cuscutae Semen(CS) and their combination(Ssangbohwan, SBH) have the effect of suppressing Receptor activator of nuclear factor kappa-B ligand(RANKL)-induced osteoclast differentiation. The second purpose of this study is to find out whether the water extract of RRP, CS and SBH have the effect of inhibiting osteoporosis in an osteoporosis model induced by lipopolysaccharide(LPS). Methods: After promoting differentiation of osteoclasts by treating the RANKL, we observed the effect by the administration of RRP, CS and SBH. In addition, by means of Reverse transcription polymerase chain reaction(RT-PCR), we assayed mRNA expression levels of NFATc1, c-Fos, TRAP and GAPDHS(Glyceraldehyde-3-phosphate dehydrogenase, spermatogeni) from bone marrow macrophages(BMMs). Similarly, the protein expression levels of NFATc1 (Nuclear factor of activated T-cells, cytoplasmic1), C-Fos, MAPKs(Mitogen-activated protein kinases) and β-actin in cell lysates were analyzed by means of Western Blotting. Finally, we determined the anti-osteoporotic effects of RRP, CS and SBH, through the use of Lipopolysaccharide-induced bone-loss mouse. Results: RRP, CS and SBH showed remarkable inhibitive effect on RANKL-treated osteoclast differentiation without cytotoxicity. SBH inhibited the phosphorylation of p38, Jun N-terminal kinases(JNK), and I-κB and down-regulated the induction of c-Fos and NFATc1 by RANKL. RRP, CS suppressed degradation of I-κB, but it did not affect c-Fos and NFATc1 by RANKL. Lastly, in vivo data showed that RRP and SBH prevented bone erosion by LPS treatment. Conclusions: These results demonstrate SBH can be effective remedy for bone-loss diseases such as osteoporosis. Key Words: Rehmanniae Radix Preparat (RRP); Cuscutae Semen (CS); Ssangbohwan (SBH); Osteoclast differentiation; Osteoporosis.