bcl-2在受损面神经运动神经元中的表达与定位

Expression of bcl-2 in facial motoneurons and its ultrastructural localization following facial nerve injury

目的 研究面神经损伤后其运动神经元胞体bcl 2表达同胞体损伤的关系。方法 行面神经高位、低位断伤和茎乳孔压榨伤 ,术后饲养 1、3、7、15、30和 6 0d ,取面神经核团 ,利用免疫组化、原位杂交和免疫电镜技术 ,并用图像分析仪分析bcl 2表达程度。结果 正常未损伤面神经运动神经元胞体bcl 2高表达 ,受损后 1d的bcl 2表达增强 ,但在损伤后 3d表达下降 ,15d表达最弱 (P <0 .0 5 ) ,以后有所恢复 ,到损伤后 2个月 (6 0d)基本恢复到正常水平 (P >0 .0 5 )。bcl 2的表达同损伤程度和损伤部位有关 (0 .0 1<P <0 .0 5 )。bcl 2mRNA和bcl 2蛋白表达一致。免疫电镜发现bcl 2蛋白主要定位于神经元胞体中的线粒体、内质网和核膜上。结论 bcl 2转录和翻译可能同面神经核团中运动神经元胞体的死亡相关。通过转基因技术调节bcl 2基因的表达 。

Objective To explore the expression of bcl 2 in facial motoneurons and its subcellular distribution. Methods Wistar rats were used in this study. Facial nerve transection was performed at stylomastoid foramen or internal acoustic meatus. Facial nerve crush was made at stylomastiod foramen. The animal survived for 1, 3, 7, 15, 30 and 60 days respectively. Facial nucleus was treated with bcl 2 monoclonal antibody or bcl 2 DIG labelling probe and studied with immunohistochemstry and in situ hybridization. The bcl 2 positive motoneuron was investigated with immuno electron microscope. Results It was demonstrated that bcl 2 protein level was corresponded with bcl 2 mRNA expression. The level of bcl 2 expression in facial motoneurons was high in normal facial nerve. It increased on the first day and declined on the third day post transection in facial motoneuron. It reached the lowest level on the 15th days following facial nerve injury ( P <0.05). The expression recovered to normal level in two months ( P >0.05). After facial nerve transected, the reduction of bcl 2 expression was more significant when facial nerve transected close to facial nucleus than that far from facial nucleus ( P <0.05). Comparing to facial nerve transection in stylomastoid foramen, there was more intensive bcl 2 expression following facial nerve crush ( P <0.05). Further study showed that bcl 2 primarily resided in the nuclear envelop, endoplasmic reticulum and mitochondrial membrane. Conclusions These data indicated that high level bcl 2 protein may prevent facial motoneuron death following facial nerve injury. It is suggested that overexpression bcl 2 by transgene may prevent facial motoneurons death.