大鼠磨牙施加重度正畸力诱导牙根吸收过程中骨保护素及核因子κB受体活化因子配体（RANKL）mRNA的表达

Expression of mRNA for osteoprotegerin and receptor activator of nuclear factor kappa beta ligand (RANKL) during root resorption induced by the application of heavy orthodontic forces on rat molars.

作者信息

Low Eva, Zoellner Hans, Kharbanda Om Prakash, Darendeliler M Ali

机构信息

Faculty of Dentistry, University of Sydney, Sydney Dental Hospital, Sydney, Australia.

出版信息

Am J Orthod Dentofacial Orthop. 2005 Oct;128(4):497-503. doi: 10.1016/j.ajodo.2004.03.038.

DOI:10.1016/j.ajodo.2004.03.038

PMID:16214633

Abstract

INTRODUCTION

Receptor activator of nuclear factor kappa beta ligand (RANKL) activates osteoclast differentiation, whereas this activity is blocked by osteoprotegrin (OPG), so that the relative expression of these 2 proteins might contribute to bone and root resorption during orthodontic tooth movement. We describe experiments with RANKL and OPG mRNA expression in rats subjected to orthodontic forces. It was hypothesized that the ratios of RANKL to OPG expression would increase during root resorption processes.

METHODS

Fixed Sentalloy (GAC, Bohemia, NY) closed-coil springs capable of delivering approximately 100 g of force were applied for mesial movement of the mandibular left first molar in 9 male, 7-week-old Wistar rats; the right mandibular molar was used as an internal control for each animal. After 14 days, the rats were killed; tissues from 2 rats were examined by paraffin histology, and high-quality messenger ribonucleic acid (mRNA) was extracted from 4-mm widths of the mesial bony tissues in the remaining animals.

RESULTS

Paraffin sections showed osteoclastic resorption of roots on the mesial surfaces of teeth subjected to orthodontic forces. The integrity of mRNA was confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) for the housekeeping gene GAPDH, and that of primers specific for OPG and RANKL was determined by RT-PCR for these genes in material isolated from the UM106 rat cell line known to express both proteins. Densitometric analysis of the RT-PCR OPG product showed an increase in background levels of OPG mRNA in bony tissues subjected to orthodontic forces in all animals studied (P < .05). In contrast, low levels of mRNA for RANKL were detected in only 5 animals and only in association with orthodontic forces.

CONCLUSIONS

Data are consistent with changes in levels of OPG and RANKL in tissues subjected to orthodontic forces and experiencing root resorption.

摘要

引言

核因子κB受体激活剂配体（RANKL）可激活破骨细胞分化，而骨保护素（OPG）可阻断此活性，因此这两种蛋白的相对表达可能在正畸牙齿移动过程中导致骨吸收和牙根吸收。我们描述了对受正畸力作用的大鼠中RANKL和OPG mRNA表达的实验。研究假设是在牙根吸收过程中RANKL与OPG表达的比率会增加。

方法

使用能够施加约100 g力的固定Sentalloy（GAC，纽约州波希米亚）闭合圈弹簧，使9只7周龄雄性Wistar大鼠的下颌左侧第一磨牙向近中移动；每只动物的右侧下颌磨牙用作自身对照。14天后，处死大鼠；取2只大鼠的组织进行石蜡组织学检查，并从其余动物近中骨组织4 mm宽度处提取高质量信使核糖核酸（mRNA）。

结果

石蜡切片显示，受正畸力作用牙齿的近中面存在牙根破骨吸收。通过看家基因甘油醛-3-磷酸脱氢酶（GAPDH）的逆转录聚合酶链反应（RT-PCR）确认了mRNA的完整性，并通过RT-PCR在已知表达这两种蛋白的UM106大鼠细胞系分离的材料中检测了OPG和RANKL特异性引物的完整性。对RT-PCR OPG产物的光密度分析显示，在所有研究动物中，受正畸力作用的骨组织中OPG mRNA的背景水平升高（P <.05）。相比之下，仅在5只动物中检测到低水平的RANKL mRNA，且仅与正畸力有关。