大鼠生长早期改变食物负荷对颞下颌关节软骨可聚蛋白聚糖酶-1和金属蛋白酶组织抑制因子-3表达的影响

Expression of Aggrecanase-1 and TIMP-3 in Mandibular Dondylar Cartilage of Rats during Early Growth and Altered Dietary Loading

目的观察大鼠生长早期改变食物硬度造成颞下颌关节负荷改变后颞下颌关节软骨内可聚蛋白聚糖酶-1和金属蛋白酶组织抑制因子-3(TIMP-3)的表达变化,并探讨其变化机制。方法 100只15 d龄雌性大鼠,21 d龄断奶后随机分为两组,实验组50只改喂极硬块状食物,对照组50只喂粉末样食物,改变食物后6 h、12 h、24 h、48 h及9 d每组分别各处死10只大鼠,采用免疫组化法及蛋白免疫印迹法半定量分别检测可聚蛋白聚糖酶-1和TIMP-3在髁突软骨细胞的表达情况。结果免疫组化发现,在所有时间段,可聚蛋白聚糖酶-1和TIMP-3主要表达在两组髁突软骨增殖层和上层肥大层的软骨细胞,可聚蛋白聚糖酶-1在两组髁突软骨下肥大层以及基质中亦有弱表达;蛋白免疫印迹结果显示,在12 h、24 h实验组可聚蛋白聚糖酶-1相对灰度值明显高于对照组(P<0.05);在6 h时间点上,实验组TIMP-3相对灰度值明显低于对照组(P<0.01);其他时间段两组表达差异无统计学意义(P>0.05)。结论改变食物硬度造成大鼠颞下颌关节负荷改变,可聚蛋白聚糖酶-1和TIMP-3参与髁状突软骨代谢,其表达变化属生理范围内,是改变食物负荷极早期的一种敏感、暂时、适应性改变。

Objective To test the hypothesis that aggrecanase-1 and tissue inhibitors of metalloproteinases-3（TIMP-3）play important role via affecting the matrix metabolism during altered dietary loading on mandibular condylar cartilage in early growth stage.Methods One hundred female Sprague-Dawley rats were nursed and fed with soft powdery food from 15 days of age.After weaning,all rats were randomly assigned into two groups：50 animals fed with soft diet and 50 fed with hard diet.Ten soft-and ten hard-diet rats were killed at 6 hours,12 hours,24 hours,48 hours and 9 days after initiation of the experiment at 21 days of age.Results Immunohistochemical analysis showed aggrecanase-1 and TIMP-3 mainly localized in chondrocytes of proliferative and upper hypertrophic zones in cartilage at all time points in both groups.The western blotting analysis showed aggrecanase-1 in experimental groups were statistically significantly higher than those of control groups at 12 hours and 24 hours,and TIMP-3 in experimental groups were lower than those of control groups at 6 hours time points.There was no statistically significant difference at later time points.Conclusion The change of food hardness may cause change of dietary loading on mandibular condylar.Aggrecanase-1 and TIMP-3 might be involved in cartilage metabolism,and the expression indicates a sensitive,temporary and adaptative change in cartilage metabolism in the physiologic range to loading altered by different diets.