Objective: To determine the influence of altered masticatory loading on Indian hedgehog (Ihh)-parathyroid hormone-like related protein (PThrP) pathway in the condylar cartilage of growing rabbits.
Methods: A total of 48 10-day-old rabbits were randomly divided into two groups and fed different kinds of food, such as solid diet and soft diet. The animals were sacrificed after 2, 4, 6, and 8 weeks. Difference of Ihh and PThrP expression levels induced by altered masticatory loading was tested by hematoxylin-eosin (HE), immunohistochemistry, Western blot, and real-time polymerase chain reaction (PCR).
Results: The thickness of condylar cartilage and expression levels of Ihh and PThrP proteins and mRNA of the solid diet groups exceeded those of the soft diet groups. The decreasing tendencies of the expression levels of Ihh and PThrP proteins and mRNA were observed at 2, 4, 6, 8 weeks.
Conclusions: Low masticatory loading may delay or inhibit the development of condylar cartilage and its growing factors Ihh and PThrP. Therefore, masticatory loading plays an important role in the development of condylar cartilage.
目的 分析不同咀嚼负荷作用下，幼兔髁突软骨内印度豪猪蛋白（Ihh）-人甲状旁腺激素相关蛋白（PThrP）通路表达的差异性，探讨咀嚼应力负荷对髁突软骨Ihh-PThrP信号通路的影响。方法 选取10 d龄幼兔48只，随机分为硬食组和软食组，分别喂以同种颗粒状（硬食）和粉状（软食），于饲养的第2、4、6、8周处死。采用苏木精-伊红（HE）染色、免疫组织化学、免疫印迹、实时定量荧光聚合酶链反应检测Ihh和PThrP mRNA和蛋白的动态变化。结果 HE染色显示硬食组髁突软骨厚度高于软食组的厚度；第2、4、6、8周，Ihh蛋白、PThrP蛋白和mRNA表达量在两组中呈递减趋势；软食组中Ihh和PThrP蛋白以及mRNA表达量显著低于硬食组。结论 较低的咀嚼负荷会造成髁突软骨生长因子Ihh和PThrP分泌减少，Ihh-PThrP通路表达迟缓，软骨发育受阻碍；适当的咀嚼负荷对髁突的正常发育有至关重要的作用。.
Keywords: Indian hedgehog; condylar cartilage; mastication; parathyroid hormone-like related protein.