神经生长因子在损伤牙牙髓中的表达变化

Expression Changes of Nerve Growth Factors (NGF) in Pulps of Injury Teeth

目的 :探讨神经生长因子 (NGF)在牙齿损伤过程中的表达变化及作用。方法 :应用免疫组织化学方法显微图像分析比较正常和机械损伤状态下NGF在牙髓组织中的表达变化。结果 :在正常牙髓组织中NGF染色呈阴性 ,损伤 0h组牙髓中NGF低水平表达 ,损伤 3d组牙髓NGF染色强阳性 ,损伤 5d后NGF表达开始减弱 ;损伤 9d后表达恢复到正常水平。结论

Objective: The aim of this study is to investigate the expression and functions of nerve growth factors during teeth injury.Methods: Twenty male Wistar rats were given mechanical irritation in upper first molar and their molecular and biological changes were examined in different periods. Four of them were killed immediately after the teeth were irritated, the other four were killed 3 days, 5days, and 9 days respectively after the teeth were stimulated. The perfusion was performed through the left ventricle with 4% paraformaldehyde and 0 2% picric acid in 0 1% phosphate buffer. The maxilla was decalcified and embedded. Sections of 15μm in thickness were cut with freezing macrodome in the sagittal planes. Then the sections were stained with immunohistochemical method to observe changes of NGF in the injured dental pulp, comparing with that in the normal dental pulp. In the end, we observed the NGF distribution in the pulp under optical microscope, and analyzed the expression level of NGF with the image pattern analysis instrument. The results were statistically analyzed.Results: In the normal group, the NGF expression was not observed.In the experimental group of zero hour,the NGF expression could be observed, but was very low. In the experimental group of three days, the NGF expression increased greatly, and the positive sites mainly distributed in the odontoblastic and the sub_odontoblastic layer. They also distributed in dentinal tubules. But in the group of 5 days, the level of NGF decreased. In the group of 9 days, it was the same as that of the normal group. Using the image pattern analysis instruments and statistical analysis, the results clearly showed that the expression level were lower in the group of three days than that of the other groups, and the expression levels of the groups 0 and 5 days were lower than that of the normal control group, however, that of 9_day group was the same as the normal group.Conclusion: NGF may play a role in the reaction and nerve restoration after teeth injury and, the expression change in different stages.\;