模拟失重下大鼠下颌牙槽骨形态改变的初步探讨

The morphological changes of mandibular alveolar bone in rats under the conditions of simulated weightlessness-a pilot study

目的:初步探讨模拟失重下大鼠牙槽骨骨质是否存在骨丧失。方法:将12只SD雄性大鼠,随机分为2组(n=6),对照组不做任何干预,悬尾组大鼠连续悬吊4周后处死各组大鼠,并取其下颌骨磨牙区标本,分别通过Micro CT扫描重建分析比较两组大鼠牙槽骨的骨体积分数(BV/TV,%)、骨小梁厚度(Tb.Th,μm)、骨小梁数量(Tb.N,mm-1)和平均密度MD值(CT);SEM观察比较两组大鼠牙槽骨骨细胞和骨胶原纤维情况;能谱分析测定各大鼠感兴趣区域的钙、磷含量。结果:Micro CT扫描结果可见,悬尾组大鼠下颌磨牙根分叉下的牙槽骨骨质存在一定程度的骨丧失;下颌牙槽骨的BV/TV、Tb.N和MD值均较对照组明显下降(P<0.05),Tb.Th与对照组相比无明显差异(P>0.05)。SEM可见,悬尾组大鼠牙槽骨骨细胞皱缩,且排列紊乱;骨胶原纤维结构杂乱,失去正常条索状形态。能谱分析结果显示,悬尾组大鼠的钙、磷含量曲线波动幅度明显减少。结论:模拟失重下大鼠牙槽骨骨质也可存在一定程度的骨丧失。

AIM： To investigate the alveolar bone loss in rats under simulated weightlessness condition.METHODS： 12 male SD rats were divided randomly into the control group and the tail suspension group（ TS group）（ n = 6）. After 4 w tail-suspension,all rats were sacrificed and the alveolar bone of the mandibular molar region were removed. The bone volume fraction wersus total volume（ BV / TV,%）,trabecular bone thickness（ Tb. Th,μm）,trabecular bone number（ Tb. N,mm^-1） and average density（ mean density,MD） of the 2 groups were compared by Micro CT analysis. Bone cells and bone collagen fibers were observed by SEM. The relative contents of calcium and phosphorus in alveolar bone were measured with energy spectrum system. RESULTS： Bone loss was observed by Micro CT in the interradicular septum of the mandibular teeth in the TS group. Significant decrease was observed in BV / TV,Tb. N and MD in the TS group（ P〈0. 05）. The Tb. Th didn ＇t show a significant change between the two groups（ P〈0. 05）.SEM study showed that osteocytes of TS group shrinked and lined in a disorder way,bone collagen was in disorder,discontinuity,poor integrity and lost the normal cord-like shape. The relative content of calcium and phosphorus declined in TS group. CONCLUSION： Weightlessness may lead to a certain degree of alveolar bone loss.