RESUMO
Objective To study the effect of different concentration of tumor necrosis factor-? (TNF-?) on expression of the receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG) mRNA on human dental follicle cells in vitro, and investigate the role of TNF-? in osteoclast formation during tooth eruption. Methods The 5th passage of primary cultured human dental follicle cells were treated with 0 (control group), 5, 10, 25, 50 and 100ng/ml TNF-?, respectively, for 6 hours. Total RNA was then isolated from human dental follicle cells and subjected to RANKL and OPG mRNA assay by reverse transcription-polymerase chain reaction (RT-PCR) technique. The relative expression levels of RANKL and OPG mRNA were normalized to ?-actin gene expression. Results The mRNA expression of OPG in human dental follicle cells with 5ng/ml TNF-? treatment was down regulated significantly compared with that in control group (P