咬合力丧失对大鼠牙周组织中iNOS表达的影响

Effect of bite force lost on the expression of iNOS in the rat periodontium

目的:研究在体内咬合力丧失的情况下,iNOS影响牙周组织改建的分子机制。方法:选用Wistar大鼠,建立咬合力丧失的动物模型,按照正常及拔牙后6h、1d、2d、3d、1周、2周、3周、4周随机分组,采用HE、免疫组化染色和RT-PCR方法,对实验结果进行单向方差分析、Dunnett检验和配对t检验,分析牙周形态变化以及牙周组织中iNOS蛋白表达的动态变化。结果:组织形态学观察发现,实验组的牙周组织较对照组有明显改建:牙周膜结构由致密变得稀疏,纤维、细胞的排列由有序到紊乱,牙槽骨骨壁由平整变得凹凸不平,甚至出现破骨细胞等。免疫组化染色结果显示:iNOS在对照组牙周膜的成纤维细胞和成骨细胞中仅表现为少量的棕黄色颗粒,而在实验组中的表达则明显增强,尤其是拔牙后的第2天和第3周。RT-PCR结果显示:咬合力丧失后,iNOSmRNA的表达呈现一定的规律性,并在拔牙后第2天、第3周先后出现2次表达高峰。统计学分析显示:实验组中iNOSmRNA的表达与咬合力的丧失有关(P<0.01),其中拔牙后的第2天和第3周与对照组的差异最为显著。结论:咬合力丧失促使牙周组织产生iNOS明显增多,且呈一定的规律性变化,导致牙周组织发生一系列退行性改变,提示iNOS很有可能是影响牙周组织改建的一个重要因素。

PURPOSE： To investigate the molecular mechanism of the effect of bite force loss on periodontium remodeling. METHODS： For establishing a rat model of different bite forces for the study, the left maxillary molars of Wistar rats were extracted and the left mandibular molar area was used as the model of the bite force lost. The animals were sacrificed after 6 hours, 1,2,3 days and 1,2,3,4weeks. The prepared tissue specimens were processed for the study of the change in the histologic morphology and the expression of iNOS protein in PDLC and osteoblasts with HE staining, immunohistochemistry and RT-PCR techniques, and the results were analyzed by one-way ANOVA,Dunnet t test and paired samples test. RESULTS： In the group of lost biting force, the derangement of periodontal ligament and resorption of alveolar bone were observed in histologic study： the structure of periodontal ligament deranged ,fibers and cells arrayed abnormally, there were many holes in the alveolar bone, even osteoclasts were present; the expression of iNOS was observed dramatically changed： the expression of iNOS in periodontal ligament fibroblasts and osteoblasts was higher than normal, especially at 2 days and 3 weeks,so as the results of RT-PCR.There was a significant correlation between bite force lost and the increased expression of iNOSmRNA. CONCLUSIONS： Bite force lost significantly increased the expression of iNOSmRNA in PDLC and osteoblasts, which suggests that iNOS may play an important role in the process of periodontium remodeling.