Objective: To investigate the effect of Duanteng Yimu decoction (DTYMD) on the expression of NF-κB receptor activator ligand (RANKL) pathway and matrix metalloproteinase-9 (MMP-9) in osteoclasts and the mechanism of bone protection. Method: In vitro osteoclast culture system was established by inducing RAW264.7 macrophages. Blank group

model group

methotrexate group (2 mg·L-1) and DTYMD groups (400

600

800

1 000 mg·L-1) were set up. The osteoblasts were identified by anti-tartaric acid phosphatase (TRAP) staining. The survival rate of each group was detected by cell counting kit-8 (CCK-8) method. The protein expression of RANKL signal pathway was detected by Western blot. The expression of MMP-9 was detected by enzyme-linked immunosorbent assay (ELISA). Result: Compared with model group

the number of fusion cells in DTYMD 400

600 mg·L-1 concentration group decreased

but the difference was not statistically significant; the number of fusion cells was significantly decreased in DTYMD 800

1 000 mg·L-1 concentration groups (P<0.01). CCK-8 results showed significant decreases in survival rates of DTYMD (600

800

1 000 mg·L-1) and methotrexate (2 mg·L-1) compared with model group (P<0.05

P<0.01). Western blot results showed that the protein expression of RANKL decreased in DTYMD 1 000 mg·L-1 and methotrexate 2 mg·L-1 groups (P<0.05) compared with model group. The protein expression of OPG in DTYMD group had no significant change. The results of ELISA showed that the expression of MMP-9 decreased in DTYMD concentration group and methotrexate group compared with the model group; and the higher the DTYMD concentration was

the more significantly decreased(P<0.05). Conclusion: DTYMD may protect bone cells by down-regulating the expressions of RANKL and MMP-9 and inhibiting the differentiation and proliferation of osteoclasts.