Ozaki S, Kaneko S, Podyma-Inoue K A, Yanagishita M, Soma K
Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Sciences, Gradute School, Tokyo Medical and Dental University, Tokyo, Japan.
J Periodontal Res. 2005 Apr;40(2):110-7. doi: 10.1111/j.1600-0765.2004.00782.x.
Loss of occlusal function has been reported to induce atrophic changes in the periodontal ligament. It is likely that mechanical stress triggers the biological response of periodontal ligament. However, there have been few reports studying the correlation between mechanical stress of varying magnitude and periodontal ligament cell activities such as extracellular matrix (ECM) synthesis.
The objective of this study is to clarify the influence of the mechanical stress on changes in mRNA expression levels of type I collagen and decorin genes, as well as alkaline phosphatase (ALP) activity in response to mechanical stress of varying magnitude.
Bovine periodontal ligament cells were cultured on flexible-bottomed culture plates and placed on the BioFlex Loading Stations. Cells were elongated at 6 cycles/min (5 s on and 5 s off) at each of six levels of stretch (0.2, 1.0, 2.0, 3.0, 10, 18% increase in the surface area of the bottom) for 48 h. We measured mRNA expression levels of type I collagen and decorin genes using quantitative reverse transcription-polymerase chain reaction (RT-PCR), and ALP activity in periodontal ligament cell culture under cyclic mechanical stretching.
Mechanical tensional stress of low magnitude induced the increase of both type I collagen and decorin mRNA expression without changing ALP activity in periodontal ligament cells. Mechanical tensional stress of high magnitude induced the increase of type I collagen and decorin mRNA expression while decreasing ALP activity.
These results suggest that different magnitude of tensional force induces different responses from periodontal ligament cells, and that mechanical stress plays an important role in remodeling and functional regulation of periodontal ligament.
据报道，咬合功能丧失会导致牙周韧带发生萎缩性变化。机械应力很可能触发牙周韧带的生物学反应。然而，很少有研究报道不同强度的机械应力与牙周韧带细胞活动（如细胞外基质（ECM）合成）之间的相关性。
本研究旨在阐明不同强度的机械应力对I型胶原蛋白和核心蛋白聚糖基因mRNA表达水平变化的影响，以及对不同强度机械应力下碱性磷酸酶（ALP）活性的影响。
将牛牙周韧带细胞培养在底部可弯曲的培养板上，并放置在BioFlex加载站上。细胞以6个周期/分钟（5秒加载和5秒卸载）的频率在六个拉伸水平（底部表面积分别增加0.2%、1.0%、2.0%、3.0%、10%、18%）下拉伸48小时。我们使用定量逆转录-聚合酶链反应（RT-PCR）测量I型胶原蛋白和核心蛋白聚糖基因的mRNA表达水平，并测量循环机械拉伸下牙周韧带细胞培养中的ALP活性。
低强度的机械拉伸应力可诱导牙周韧带细胞中I型胶原蛋白和核心蛋白聚糖mRNA表达增加，而不改变ALP活性。高强度的机械拉伸应力可诱导I型胶原蛋白和核心蛋白聚糖mRNA表达增加，同时降低ALP活性。
这些结果表明，不同强度的拉伸力会诱导牙周韧带细胞产生不同的反应，并且机械应力在牙周韧带的重塑和功能调节中起重要作用。
