青春期大鼠髁突软骨内润滑素的表达研究

Study of the expression of lubricin in condylar cartilage of puberty rats

目的研究无干预措施下青春期大鼠髁突软骨内润滑素的表达情况。方法选取5组5周龄的雌性SD大鼠(每组5只),软食喂养下分别于3、7、14、21和30 d处死,下颌骨髁突制作切片,行苏木素-伊红(HE)染色及Envision二步法进行免疫组织化学染色检查,应用倒置相差光学显微镜、光学显微照相系统观察和拍摄图片,测量润滑素阳性区域的累积光密度值,比较不同实验时点润滑素的表达情况。结果大鼠髁突软骨细胞具有独特的层域化分带;髁突全层均有润滑素的表达,其中静止层仅见少量润滑素表达;纤维层中,润滑素聚集在最表层细胞的细胞浆中;增殖层中,润滑素分布于整个软骨细胞中;肥大层中,润滑素分布于肥大的软骨陷窝内细胞质中,浅肥大层表达较强,靠近深肥大层逐渐减弱。在相同时点,髁突后部软骨增殖层润滑素阳性区域的累积光密度值均高于肥大层润滑素的累积光密度值(P均<0.05);在不同时点,髁突后部增殖层和肥大层润滑素阳性区域的平均累积光密度均无明显变化(P均>0.05)。结论在青春期SD大鼠髁突软骨中,润滑素表达水平呈现一定的连续性和稳定性,这为髁突生理性改建、下颌骨正常发育提供了良好的内环境。

Objective To detect the expression of lubricin in the condylar cartilage of the puberty rats without interventions. Methods Twenty five 5-week-old female Sprague-Dawley（ SD） rats were randomly divided into five groups（ n = 5）. The animals were fed with ground pellets and sacrificed on 3-,7-,14-,21-and 30-d. The mandibular condyle tissues were prepared for H. E and immunohistochemical staining. Under inverted optical microscope,integrated optical density（ IOD） of the area of positive lubricin was quantitatively analyzed. The expression levels of lubricin were measured and compared at different time points. Results Condylar cartilages presented with varying characteristics among different layers. Lubricin was expressed throughout the whole condyle. Lubricin was slightly expressed in the static zone. In the articular fibrous zone,lubricin was abundant in the chondrocyte cytoplasm of the superficial layer. In the proliferative zone,lubricin was distributed throughout the condylar cartilages. In the hypertrophic zone,lubricin was observed in the cytoplasm of hypertropic cartilage lacuna,with higher expression in the superficial layer than the deep layer. At the same time point,IOD values of the positive lubricin area in the proliferative zone were significantly higher compared with those in the hypertrophic zone of the posterior mandibular condyle（ all P〈0. 05）. In both the proliferative and hypertrophic zones,no significant changes were documented in the IOD values at varying time points（ all P〈0. 05）. Conclusion In the condylar cartilage of the puberty SD rats,lubricin was stably and continuously expressed,creating a sound inner environment for physiological reconstruction of mandibular condyle and normal growth of the mandible.