面神经损伤后BDNF和FGF-2的分布与表达的实验研究

Expression and distribution of BDNF and FGF-2 in rat facial nerve after lesion

目的：研究脑源性神经营养因子（ｂｒａｉｎ ｄｅｒｉｖｅｄ ｎｅｕｒｏｔｒｏｐｈｉｃ ｆａｃｔｏｒ，ＢＤＮＦ）和成纤维细胞生长因子－２（ｆｉｂｒｏｂｌａｓｔ ｇｒｏｗｔｈ ｆａｃｔｏｒ－２，ＦＧＦ－２）在大鼠面神经的分布和表达以及面神经损伤后的改变。方法：制作大鼠右面神经损伤模型，应用原位杂交检测ＢＤＮＦｍＲＮＡ和ＦＧＦ－２ｍＲＮＡ在损伤面神经两断端及左侧对照组神经的表达情况，结合计算机图像分析技术测定其灰度值。结果：ＢＤＮＦｍＲＮＡ在对照侧神经和损伤神经近侧端呈弱阳性表达，主要位于轴突和髓鞘周围的雪旺细胞（Ｓｃｈｗａｎｎ ｃｅｌｌ，ＳＣ）内，损伤后不同时间组表达差异无显著意义（Ｐ＞０．０５），在损伤神经远侧端杂交信号７天开始增强至２８天（Ｐ＜０．０１＝；ＦＧＦ－２ｍＲＮＡ在对照侧神经表达极弱，主要位于轴突和髓鞘周围的ＳＣ内，神经损伤后近侧端７天杂交信号开始增强至２８天（Ｐ＜０．０１＝，而远侧端杂交信号１天即开始增强，３天最强（Ｐ＜０．０１＝，２８天达对照侧水平（Ｐ＞０．０５）。结论：损伤面神经局部ＢＤＮＦｍＲＮＡ和ＦＧＦ-２ｍＲＮＡ的表达增高可能与轴突的再生和髓鞘的形成有关。

Objective:To investigate the expressions and distributions of brain derived neurotrophic factor(BDNF) and fibroblast growth factor-2(FGF-2) at the intact and transected facial nerves-Methods:The right facial nerve was transected 6mm distal to the stylomastoid foraman in adult Wistar rats except the normal group.The nerve segments extending 5mm either distally or proximally from the transected site and identical segments of the contralateral unoperated nerve were collected-Serial 20μm cryosections were cut.BDNF and FGF-2 signals were studied by in situ hybridyzation and image analysis.Results:BDNFmRNA was found to be weakly expressed in intact facial nerves and proximal nerve stumps,and no significant changes were found among them(P>0.05).H owever,there was a continuous slow increase of BDNFmRNA in distal stamps starting 7 days after lesion and reaching maximal levels 28 days(P<0.01);FGF-2mRNA expressed very weakly in the intact facial nerves.In the proximal nerve stumps,a strong up-regulation of FGF-2mRNA occurred 7 days after lesion(P<0.01).In the distal nerve stumps,FGF-2mRNA also displayed a significant increase1 day after transaction(P<0.01),however,it decreased and reached control levels at 28 days(P>0.05).Conclusion:Upregulations of BDNFmRNA and FGF-2mRNA at the injured facial nerve suggest a possible physiological function of BDNF and FGF-2 during the regeneration and myelination process,and different mechanisms of BDNF and FGF-2 synthesis in injured facial nerve are suggested.[Chinese Arch Otolaryngol Head Neck Surg,2002;9(1):39～42 From the Department of Otolaryngology,First Affiliated Hospital of Henan Medical University,Zhengzhou 450052(Dr.Qin Zhaobing)]