Objective      To investigate the potential role of a system containing osteoprotegerin (OPG)

receptor activator of NF-κB ligand (RANKL)

and receptor activator of nuclear factor-kappa B (RANK)

also as

OPG/RANKL/RANK system in the resorption and remodeling mechanisms of alveolar bone.       Methods      Mouse RAW264.7 cell line was induced to osteoclasts in vitro

and mouse MC3T3-E1 cell line was treated with bone resorption supernatant. The control cells was cultured with regular medium. The expression levels of OPG

RANKL and RANK in the cells was detected by immunofluorescence assay. Thirty 8-week-old male SD rats were used to establish the alveolar bone resorption model with the injection of E-LPS. Immunohistochemical S-P method was used to investigate the expression of OPG

RANKL and RANK in the animal model.       Results      The expression of OPG in MC3T3-E1 cells was up-regulated after 7 days’ treatment with bone resorption supernatant than in control cells (29.636±5.652 vs 15.568±1.229

P0.01）

while

the RANKL expression was down-regulated （6.806±1.738 vs 18.082±2.732

P0.01）. The ratio of OPG to RANKL was up-regulated too （P0.05）. The OPG level in periodontal tissues of rats was decreased compared with the tissue without resorption. But the expression of RANKL was increased.       Conclusion      OPG/RANKL/RANK system is involved in the bone resorption and remodeling. Osteoclast bone absorbent supernatants might affect the ratio of OPG to RANKL by regulating of the differentiation and activity of osteoblast-like cells

and thus regulate the dynamic balance of bone formation and resorption.