Reaction of intercellular network of osteocytes in alveolar bone during experimental tooth movement

骨细胞埋藏在骨基质内，并在骨表面上相邻的骨细胞和/或成骨细胞之间形成复杂的细胞网络。提示骨细胞在骨重建中具有重要作用。然而，在正畸牙齿移动过程中，机械应力对牙槽骨中骨细胞及其细胞间网络的影响却知之甚少。本研究采用形态计量学、免疫组织化学和原位杂交技术，对实验性牙齿移动过程中压力侧和张力侧牙槽骨细胞间网络进行了研究.动物和实验性牙齿移动在8周龄的雄性Wistar大鼠中，通过镍-钛超弹性线（直径0.01英寸）以10 g的平均负荷迫使上第一磨牙近中移动。我们先前的研究显示此方法适用于观察透明化牙周组织周围的骨细胞.实验性牙齿移动过程中骨细胞的形态学变化我们建立了一种用Alexa 488标记鬼笔环肽和DAPI在共聚焦激光扫描显微镜（CLSM）下免疫荧光观察骨细胞的方法。激光共聚焦显微镜显示，玻璃样变性牙周组织周围骨细胞染色质浓缩、核碎裂、胞质破坏。并采用TUNEL法和电镜观察骨细胞死亡情况。结果表明，实验性牙齿移动过程中骨细胞的死亡可能是由于成骨细胞与骨细胞之间的细胞间网络被破坏，而不是骨细胞对机械应力的直接反应。为了了解牙槽骨细胞间网络的动态变化，有必要进一步研究与骨代谢相关的几种生长因子和细胞因子的参与。

Osteocytes are buried within the bone matrix and form complicated cellular networks between neighboring osteocytes and/or osteoblasts on bone surfaces. It is proposed that osteocytes have very important role of bone remodeling. However little is known on the effect of mechanical stress on osteocytes and their intercellular network in the alveolar bone during orthodontic tooth movement. The purpose of this study was to examine the intercellular network in alveolar bone on pressure and tension sides during experimental tooth movement, using morphometrical analysis, immunohistochemistry and in situ hybridization technique.1. Animals and experimental tooth movement.In 8-week-old male Wistar rats, the upper first molar was forced to move mesially with an average load of 10g by a nickel-titanium superelastic wire (0.01 inch in diam.). We previously reported that the method was suitable for the observation of osteocytes adjacent to the hyalinized periodontal tissue.2. Morphological change of osteocytes during experimental tooth movement.We developed a method to observe osteocytes by immunofluoresence with Alexa 488 labelled phalloidin and DAPI under confocal laser scanning microscopy (CLSM). CLSM showed that chromatin condensation, nuclear fragmentation and cytoplasmic destruction appeared in several osteocytes adjacent to the hyalinized periodontal tissues. Also, we carried out TUNEL method and electronmicroscopic observation to identify the cell death of osteocytes. The results indicate that cell death of osteocytes during experimental tooth movement may be due to disruption of intercellular network between osteoblasts and osteocyte, but not to direct reaction of osteocytes by mechanical stress. To know the dynamics of intercellular network in alveolar bone, further investigations concerning involvement of several growth factors and cytokines related to bone metabolism is necessary.