Previous researches have proved that Pueraria lobata up-regulates bone mineral contents and bonemineral density in bone-loss model, ovariectomized mice and orchidectomized rats. However, the precise effectsand mechanisms of Pueraria lobata on osteoclast differentiation and bone resorbing activity of mature osteoclastsstill remains unknown. Therefore, we investigated the effect and mechanism of Pueraria lobata on receptor activatorof nuclear factor-κB ligand (RANKL) and macrophage colony stimulation factor (M-CSF)-inducedosteoclast differentiation in bone marrow macro-phages (BMMs). First of all, we treated BMMs derived frommice with various concentrations of Pueraria lobata in order to perform screening by tartrate-resistant acidphosphatase (TRAP) staining. Also, we conducted western blotting and RT-PCR for the purpose of verifying thetreatment mechanism of Pueraria lobata and lastly, we used hydroxyapatite-coated plate to evaluate the effects ofPueraria lobata on bone resorbing activity of mature osteoclasts. As a result, Pueraria lobata has inhibitoryeffect on phosphorylation of p38, Akt, c-Jun N-terminal kinase (JNK), and IκB which are essential early signalingpathway of osteoclastogenesis. Also, the inactivation of nuclear factor of activated T cells (NFAT)c1, and c-Foswhich is caused by Pueraria lobata is followed by the suppression effects of Pueraria lobata on osteoclastrelatedvarious genes, osteoclast-associated receptor (OSCAR), TRAP, Integrin β3, osteoclast stimulatorytransmembrane protein (OC-STAMP), and dendritic cell-specific transmembrane protein (DC-STAMP).
Particularly, Pueraria lobata blocks the formation of pit area on hydroxyapatite-coated plate in a dose-dependentmanner as well as the mRNA expression of Cathepsin K, which is associated with bone resorbing activity. Theseresults demonstrate the molecular mechanism relating to anti-osteoclastogenesis effect of Pueraria lobata as wellas the inhibitory effect of Pueraria lobata on mature osteoclast formation and bone resorbing activity.