面神经损伤后面运动神经元两种神经营养因子的表达

Expression of BDNF and FGF-2 following axotomy in rat facial motoneurons

目的 研究脑源性神经营养因子 (brainderivedneurotrophicfactor ,BDNF)和成纤维细胞生长因子 2 (fibroblastgrowthfactor 2 ,FGF 2 )在大鼠面运动神经元 (facialmotoneuron ,FMN)的正常分布和面神经损伤再生过程中的表达改变。方法 制造大鼠右面神经损伤模型 ,应用原位杂交和免疫组化检测BDNFmRNA及其蛋白和FGF 2mRNA及其蛋白在FMN的表达 ,结合计算机图像分析技术测定双侧FMN反应产物的阳性细胞数比和灰度值百分比。结果 BDNFmRNA及其蛋白阳性细胞分布于正常面神经核各亚核 ,除神经元细胞外其周围胶质细胞也染色 ,面神经损伤后 1d ,损伤侧面神经核BDNFmRNA及其蛋白阳性神经元细胞和胶质细胞数量及染色强度均快速增高 ;FGF 2mRNA及其蛋白主要分布于正常面神经核腹侧亚核神经元胞浆中 ,面神经损伤后损伤侧FMN中FGF 2mRNA信号7d开始增强 ,而其蛋白反应产物则在损伤后 3和 7d显著减少。结论 正常FMN可能存在BDNF的自分泌和旁分泌作用及FGF 2的自分泌作用 ;面神经损伤早期 ,靶源性FGF 2的减少导致FMN中FGF 2蛋白表达下降 ,提示应用外源性FGF

Objective To study the expression and distribution of brain derived neurotrophic factor (BDNF) and fibroblast growth factor 2 (FGF 2) in normal facial motoneurons (FMNs) and in FMNs following axotomy. Methods The right facial nerves were transected 6 mm distal to the stylomastoid foraman in adult Wistar rats except the normal group. Serial 20 μm cryosections were cut through the whole brainstems. Expressions of BDNF and FGF 2 mRNA as well as BDNF and FGF 2 protein were studied by in situ hybridization, immunohistochemisty and image analysis. Results BDNF mRNA and its protein were observed in widespread areas of normal rat facial nucleus, and those increased 1 day after axotomy. In addition to neurons, glial cells were also stained. FGF 2 mRNA and its protein were mainly localized in normal FMNs of ventral facial nucleus. After axotomy, expression of FGF 2 mRNA started to up regulat in FMNs at 7 days, however FGF 2 protein drastically reduced at 3 and 7 days. Conclusion In addition to target supporting, there may be BDNF autocrine and paracrine mechanisms as well as FGF 2 autocrine mechanisms in normal rat FMN. When target derived BDNF is deprived, alternative sources of BDNF support may substitute immediately after axotomy. However, deprivating of target derived FGF 2 may result in down regulation of FGF 2 protein in adult rat FMNs at early stage after axotomy. These suggest that the exogenous FGF 2 might provide a supportive environment for the recovery of metabolism and function of FMNs at early stage following axotomy.