Effects of thyroid stimulating hormone on osteoclast differentiation

Objective To study the effects of thyroid stimulating hormone(TSH) on the differentiation of RAW264.7 cells into osteoclast like cells.Methods RAW264.7 cells were induced to differentiate into osteoclasts by addition of ligand of receptor activator of NF-κB(RANKL),and treated with different doses of TSH for 7 days.Tartrate resistant acid phosphatase(TRAP) staining was used to identify and count osteoclasts.The mRNA expression of osteoclastic phenotypes and functioning genes including TRAP,matrix metalloproteinase-9(MMP-9) and Cathepsin K in different groups were detected by Real-time PCR.Results RAW264.7 cells could be induced to differentiate into mature osteoclasts and express high levels of TRAP,MMP-9 and Cathepsin K by RANKL.TSH dose-dependently inhibited the cell differentiation and down-regulated the expression of the genes above including TRAP,MMP-9 and Cathepsin K.Conclusion TSH negatively regulates osteoclast differentiation,which may contribute to the maintenance of bone mass.