咀嚼力降低对发育期大鼠髁突软骨中细胞增殖和凋亡的影响

目的：研究咀嚼力降低对发育期大鼠下颌髁突软骨细胞增殖和细胞凋亡活性的影响。方法：40只18d雄性大鼠随机分为两组。一组喂以标准的硬食,另一组以粉末状软食喂养。于大鼠4周、5周、6周、7周龄时取其髁突软骨,分别采用免疫组织化学染色和TUNEL染色,观察髁突软骨中增殖细胞核抗原阳性细胞数和凋亡细胞数。结果：在4～7周,PCNA阳性细胞数在软、硬食组都逐步上升。但在各相同时间点,软、硬食组的PCNA阳性细胞数不存在统计学差异。在4～7周,硬食组大鼠髁突软骨中凋亡细胞数基本保持一致,而软食组凋亡细胞数随时间推移而降低,但在4周、5周、6周时,软食组的凋亡细胞数均明显多于同期硬食组（P〈0.05）。结论：咀嚼力降低对发育期大鼠髁突软骨中的细胞增殖活性影响不大,但却使细胞凋亡的数量增加,提示咀嚼力降低可能加速了髁突软骨中细胞的分化、成熟、凋亡,进而影响髁突的正常发育。

Effect of low masticatory force on cell proliferation and cell apoptosis of the condylar cartilage in growing rat.

Objective：To investigate the effect of low masticatory force on activity of cell proliferation and cell apoptosis of the condylar cartilage in growing rat.Method：forty 18 days old rats were randomly divided into 2 groups.One group received the normal hard diet foe rats;the other group received a powder soft diet.The condylar cartilage was dissected when rats were 4weeks、5weeks、6weeks、7weeks after birth.Immunohistochemical staining was used to qualitively examine the PCNA positive cell,TUNEL was chosen to detect the apoptotic cell.Result：From 4w to 7w,the number of proliferating cell increased gradually in both groups.There was no significant difference between two groups.During the experiment period,the number of apoptotic cell in condylar cartilage of hard-diet groups was on the same level.Howere,the number decreased markedly in soft-diet groups.At 4,5,6w,the number of apoptotic cell of soft-diet groups were significantly more than the hard-diet groups（P 0.05）.Conclusion：A low masticatory force has no significant effect on proliferation of cell in cartilage.But,it leads to increased number of apoptotic cell in cartilage.It suggests that decreased masticatory force induced by softdiet feeding promote the maturation and apoptosis of cell in cartilage.