Abstract:

Objective: To investigate the function of Alpl gene during orthodontic tooth movement. Methods: Firstly, agarose gel electrophoresis was used for screening heterozygote (Alpl semi-knockout group) and wildtype (wildtype group) mice, 12 mice in each group. Then orthodontic tooth movement model was established and the changes of body weight of the two groups were observed. Furthermore, maxillary samples from the two groups were collected after 7 days of orthodontic force. Micro-CT 3D reconstruction was applied to detect the distance of tooth movement in wildtype group and Alpl semi-knockout group. After demineralization, the collected maxillary samples were embedded and cut into slices. HE staining was applied to observe the histological changes in periodontal tissue. Finally, immunofluorescent staining was used to compare the expression of alkaline phosphatase(ALP) in periodontal tissue. Results: Agarose gel electrophoresis results showed that Alpl heterozygous mice were successfully generated. And the orthodontic tooth movement model was established. In addition, the body weight of the two groups both decreased significantly in the first four days and then increased. There was no significant difference in body weight within the two groups. Micro-CT 3D reconstruction result displayed that Alpl heterozygous mice gene showed less tooth movement compared with wildtype mice. Furthermore, HE staining showed that the periodontal membrane was compressed on the pressure side and widened on the tension side in both groups. However, more osteoclastic lacunaes can be seen on the pressure side in wildtype group than that in Alpl semi-konckout group. Finally, immunofluorescence staining demonstrated that periodontal tissue of wildtype mice showed extensive expression of ALP, while the expression of ALP significantly dropped in Alpl semi-knockout group. Conclusions: The deficiency of Alpl gene inhibits orthodontic tooth movement.

Key words: Alpl, orthodontic tooth movement, transgenic mice, periodontal tissue

摘要：

目的： 探讨Alpl基因在正畸牙移动中的作用。方法： 通过琼脂糖凝胶电泳实验筛选Alpl半敲除小鼠和野生型小鼠，将其分为野生组和Alpl半敲除组，每组各12只，分别对2组小鼠行正畸牙移动模型的构建，观察2组小鼠的体质量随正畸力作用时间的变化情况。收集2组小鼠加力7 d后的上颌骨样本，微型CT（micro-CT）三维重建比较野生组和Alpl半敲除组小鼠牙齿移动的距离。对收集的上颌骨样本脱钙后进行包埋切片，通过苏木精-伊红（HE）染色观察2组小鼠牙周组织的组织学改变，应用免疫荧光染色法观察比较Alpl基因的编码蛋白碱性磷酸酶（alkaline phosphatase, ALP）在2组小鼠牙周组织中的表达情况。结果： 琼脂糖凝胶电泳结果示，本实验成功繁育了双条带的Alpl半敲除小鼠。本实验成功构建了正畸牙移动模型，野生组与Alpl半敲除组小鼠体质量均在加力前4天明显下降，而后缓慢上升，体质量变化差异无统计学意义。2组小鼠上颌骨micro-CT三维重建结果示，与野生组相比，Alpl半敲除组小鼠牙移动距离较小。HE染色结果示，2组小鼠牙周膜均在压力侧变窄，张力侧增宽，但野生组牙根压力侧与Alpl组相比可见较多破骨陷窝。免疫荧光染色可见，ALP在正畸加力后的野生组牙周组织中广泛表达，但半敲除Alpl后，ALP在张力侧和压力侧的表达均显著减少。结论： Alpl基因缺乏抑制了正畸力介导的牙齿移动。

关键词: Alpl, 正畸牙移动, 转基因小鼠, 牙周组织