Abstract:

Objective　To investigate the effects of unilateral anterior crossbite on the expression of CaR，PTHrP and the proliferation and differentiation of chondrocytes in the mandibular condylar cartilage of rats. Methods　Forty-eight 6-weeks-old female SD rats were randomly divided into 3 groups according to the experimental time point (2, 4 and 8 weeks). Each group was then randomly divided into 2 subgroups (control and UAC subgroup), with 8 animals in each subgroup. UAC stimulation was applied to rats, which were killed 2, 4 and 8 weeks later. Expression of CaR，PTHrP and PPR in mandibular condylar cartilage were detected by immunohistochemical staining. mRNA of proliferation markers and differentiation markers in cartilage was detected by real-time PCR. Results　CaR expression increased at 2 weeks and PTHrP expression increased at 4 weeks. But expression of PPR, the only receptor of PTHrP, decreased significantly at 2 weeks. The expression of proliferation markers and phenotype markers of chondrocyte decreased significantly from 2 weeks, and the expression of terminal differentiation markers increased significantly from 4 weeks. Conclusion　Conclusion The unilateral anterior crossbite can induce the changes of CaR and PTHrP expression in the mandibular condylar cartilage, and thereby affect the proliferation and differentiation of chondrocytes.

Key words: temporomandibular joint, calcium-sensitive receptor, chondrocytes, differentiation, proliferation

摘要：

目的　探索单侧前牙反牙合（unilateral anterior crossbite，UAC）对大鼠下颌髁突软骨内钙离子敏感受体（calcium-sensing receptor，CaR）、甲状旁腺激素相关蛋白（parathyroid hormone-related protein，PTHrP）分子表达以及软骨细胞增殖和发育的影响。方法　选择6周龄雌性SD大鼠48只，根据实验时间点（2、4、8周）随机分为3大组，每大组再随机分为2组（对照组、UAC实验组），每组动物数量8只。对SD大鼠施加UAC刺激，于2、4、8周后分别处死各组大鼠，对颞下颌关节软骨进行CaR、PTHrP、PTHrP 受体（PPR）分子的免疫组化染色，提取软骨内mRNA进行增殖标志分子、软骨细胞表型分子和终末分化相关分子的Real-time PCR检测。结果　UAC实验组大鼠髁突软骨2周时即开始出现CaR的表达增高，4周时继发有PTHrP的表达上调，但是其惟一受体PPR的表达从2周时即显著降低；增殖标志分子和软骨细胞表型分子的表达从2周时开始显著降低，终末分化相关分子的表达从4周开始显著增高。结论　UAC可导致下颌髁突软骨内CaR、PTHrP表达改变，进而影响软骨细胞的增殖和分化状态。

关键词: 颞下颌关节, 钙离子敏感受体, 软骨细胞, 分化, 增殖