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目的:研究在髁状突软骨早期生长阶段改变食物负荷对基质金属蛋白酶-13(MMP-13)表达变化的影响,探讨其在髁状突软骨发育中的意义。方法:100只14d龄雌性大鼠同时哺乳与喂食粉末样食物,在21d龄断奶后,随机分为2组,实验组改为极硬块状食物,对照组仍然喂粉末样食物,大鼠分别于食物改变后第6、12、24、48小时以及第9天被处死,取完整髁状突软骨组织,用免疫组化方法分析MMP-13表达的变化。结果:MMP-13主要表达在髁状突软骨增殖层和上层肥大层的软骨细胞。半定量分析表明,在开始实验后,整个髁状突软骨MMP-13的表达在软、硬食物组6h点上差异有统计学意义(P<0.05),软食物组的表达高于硬食物组。但是在随后的时间点无明显差异(P>0.05)。MMP-13的表达在软食物组6h与9d、12h与9d、24h与9d、48h与9d的时间点上差异均有统计学意义(P<0.01);在硬食物组,MMP-13的表达在6h与9d、12h与9d、24h与9d、48h与9d以及6h与12h、6h与24h、6h与48h的时间点上差异均有统计学意义(P<0.05)。结论:在改变食物负荷后极早期MMP-13表达变化的时间和负荷呈依赖性,提示MMP-13表达差异是一种在生理范围内的,对负荷改变的一种敏感、暂时、适应性的软骨代谢改变。
OBJECTIVE: To investigate the effect of food load on the expression of matrix metalloproteinase-13 (MMP-13) during the early growth phase of condylar cartilage and to explore its significance in the development of condylar cartilage. METHODS: One hundred fourteen-day-old female rats were fed lactation and powdered diet at the same time. After weaning for 21 days, they were randomly divided into two groups. The experimental group was changed to very hard lumpy food. The control group was still fed powdered food. The rats were sacrificed on the 6th, 12th, 24th, 48th and the 9th day after the food was changed. The integrity of the condylar cartilage tissue was examined and the changes of MMP-13 expression were analyzed by immunohistochemistry. Results: MMP-13 was mainly expressed in chondrocytes of condylar cartilage proliferative layer and upper hypertrophic layer. Semi-quantitative analysis showed that the expression of MMP-13 in the whole condylar cartilage was significantly different from that in the soft food group at 6h (P <0.05) after the start of the experiment . However, there was no significant difference at subsequent time points (P> 0.05). The expression of MMP-13 in the soft food group at 6h and 9d, 12h and 9d, 24h and 9d, 48h and 9d were significantly different (P <0.01); in the hard food group, the expression of MMP-13 The differences were statistically significant at 6h and 9d, 12h and 9d, 24h and 9d, 48h and 9d, 6h and 12h, 6h and 24h, 6h and 48h (P <0.05). CONCLUSION: The time-dependent and load-dependent changes of MMP-13 expression during the early phase of food load change suggest that MMP-13 expression is a physiological, transient, adaptive Cartilage metabolism changes.