大鼠正畸压力侧牙槽骨改建中RANKL和OPG mRNA的表达

RANKL and OPG mRNA expression in alveolar bone on the pressure side during orthodontic tooth movement

目的研究破骨细胞核因子κB受体活化因子配基(receptor activator nuclear factor kappa B ligand,RANKL)及其伪受体骨保护因子(osteoprotegerin,OPG)的mRNA在大鼠正畸牙移动压力侧牙槽骨改建中的表达变化及时间分布特点。方法选用80只6周龄SD雄性大鼠建立正畸牙移动模型,分别在加力后2d、5d、7d、10d和14d各处死16只大鼠。HE染色观察大鼠牙周组织的形态学变化;TRAP染色计数压力侧牙槽骨组织中的破骨细胞数量;实时定量PCR方法检测RANKL和OPG mRNA的表达变化及时间分布特点。结果骨改建的最活跃期为正畸加力后的第7d,压力侧牙槽骨组织中的TRAP染色阳性破骨细胞计数随加力时间的增加而增加,第7d达到高峰,而后逐渐降低。压力侧牙槽骨组织中的RANKL和OPG mRNA表达水平均随加力时间的增加而增加,第7d达到高峰,而后均逐渐降低。结论RANKL和OPG mRNA表达的变化规律不仅与骨改建过程一致,而且也与TRAP染色阳性破骨细胞数量的变化规律一致。RANKL和OPG与正畸牙移动骨改建过程中破骨细胞的分化、形成和功能密切相关。

[ Abstract] Objective To study mRNA expression of RANKL（ receptor activator nuclear factor kappa B ligand） and its decoy receptor, OPG （osteoprotegerin） in alveolar bone on the pressure side during orthodontic tooth movement. Methods An animal model of orthodontic tooth movement was established in 80 6-week-old male SD rats. Rats were executed at 2,5,7,10 and 14 days after orthodontic force application. The morphological changes were observed by HE staining. The numbers of TRAP-positive osteoclasts in alveolar bone on the pressure side were counted. RANKL and OPG mRNA expression were quantified by real-time PCR. Results The most prominent period of bone remodeling occured at 7 day after orthodontic force application. The number of TRAP-positive osteoclasts in alveolar bone on the pressure side significantly increased in a time-dependent manner at 2-7 days. After that the number of TRAP-positive osteoclasts in alveolar bone gradually decreased. The mRNA expression of RANKL and OPG in alveolar bone on the pressure side increased in a time-dependent manner after orthodontic force application. After that it gradually decreased at 7-14 days. Conclusion The changing tendency of RANKL and OPG mRNA was consistent with the change of bone remodeling and the number of TRAP-positive osteoclasts. RANKL and OPG may play an important role in the bone remodeling during orthodontic tooth movement.