Notch-2在大鼠牙髓炎中的时空分布及其意义

Time-sequenced alteration of immunolocalization and significance of Notch-2 expression in rat pulpitis

目的:研究单纯开髓导致大鼠牙髓炎进程中Notch-2在牙髓损伤修复中的作用。方法:通过开髓建立大鼠牙髓炎模型,用免疫组织化学染色方法研究Notch-2的时空表达变化及其意义。结果:牙髓损伤早期(3 d),牙髓间充质细胞和牙髓成纤维细胞中Notch-2均呈弱阳性表达,成牙本质细胞为阴性表达。牙髓损伤中期(5 d),靠近损伤区的成牙本质细胞深层细胞Notch-2阳性表达达到高峰;同时,新生毛细血管内皮细胞呈强阳性表达。牙髓损伤晚期(7 d),Notch-2在牙髓间充质细胞、血管内皮细胞中表达均减弱,而在成牙本质细胞阳性表达达到高峰。牙髓损伤末期(14 d),Notch-2仅在成牙本质细胞下层细胞中尚有微弱表达,而其余牙髓细胞均为阴性表达。对照组正常牙髓组织Notch-2表达为阴性。结论:Notch-2在牙髓损伤应激情况下在牙髓间充质细胞和成牙本质细胞中上调表达,对于启动牙髓自我修复、诱导牙髓间充质细胞功能性分化以及抑制受损成牙本质细胞凋亡、维系和调动其相对正常的生理功能可能具有重要作用。

Objective： To investigate the immunolocalization and significance of Notch-2 expression in the process of dental pulp repair after injury. Methods： An experimental animal model of injury-induced pulpitis was established to observe the time-sequenced alteration of the expression of Notch-2. Results： Three clays post-operation, weak positive staining of Notch-2 was observed in pulp mesenchyme ceils and pulp fibroblasts but not in vascular endothelial cells or odontoblasts. Five days post-operation, strong Notch-2 reactivity was found in subodontoblasts as well as newly born capillary endothelial cells. Seven days after cavity preparation, Notch-2 staining became weaker in pulp mesenchyme cells and capillary endothelial cells, but stronger positive staining was found in odontoblasts. Two weeks post-operation, weak Notch-2 staining was seen in pulp mesenchyme cells and subodontoblasfic layer cells and was absent from odontoblasts. Notch-2 immunoreactivity was completely absent in intact rat dental pulp. Conclusion： Notch-2 is strikingly up-regulated in dental pulp mesenchyme cells in the early clays after dental injury and then shows progressively up-regulation in odontoblasts. Properly regulated activation of Notch signaling pathway is important for controlling cell fate and maintaining the correct balance among cell proliferation, differentiation and apoptosis during dental pulp repair process.