Effects Of Ursolic Acid At Different Concentrations On Proliferation And Differentiation Of Osteoclasts And Their Significances

Objective:To investigate the effects of ursolic acid（UA）on the proliferation and differentiation of osteoclast-like cells（OC）,and to explore its role in orthodontic force-induced root resorption and its relationship with OC.Methods:The mononuclear / macrophage celsl RAW264.7 were induced by OC.The induction of tacrolimus acid phosphatase（TRAP）staining and bone resorption lacunae was observed.CCK-8 method was used to select the appropriate concentration of UA for RAW264.7 cell-free biotoxicity and to observe its effect on the proliferation and differentiation of RAW264.7.In the experimental group,UA with gradient concentration of 1.0,2.5,5.0,10.0,20.0and 40.0μmol·L^-1.UA was not added in control group.RT-PCR was used to detect the expression of OC marker gene（TRAP,NFATc1）at the appropriate concentration of UA(5.0μmol·L^-1)and OC culture on day 5,and its effect on OC differentiation was observed.Results:TRAP staining and bone resorption laceration observation show that after the RAW264.7 cells were induced for 5d,the TRAP staining positive cells were found,the resorption lacunae were rounded,oval,etc,and the bottom wall was coarser,the boundary was clearer,which indicated that the RAW264.7 cells were successfully differentiated into osteoclasts.The CCK-8 detection results showed that high concentration of UA(> 10.0μmol·L^-1)significantly inhibited the proliferation of OC;the appropriate concentration of UA(5.0μmol·L^-1)was in the biological safety concentration range and could inhibit the OC proliferation;low concentration of UA(<2.5μmol·L^-1)had no effect.,At 5d,the concentration of UA could significantly inhibit the expression level of OC marker gene,indicating that UA could inhibit OC differentiation.Conclusion:UA is correlated with the proliferation and differentiation of OC;UA has inhibitory effect on OC at the appropriate concentration(5.0μmol·L^-1)in time-dependent manner.