大鼠面神经损伤后面神经核运动神经元中VGCC表达变化的研究

摘要

Objective:To investigate the expression change of voltage-gated calcium channels(VGCC) in the facial nucleus motoneurons of adult rats after facial nerve injury.Methods:The facial motor nucleus was localized by retrograde labeling with a fluorescent dye,Dil,and identified by Nissl staining.The facial nerve injury model was established by amputation of the main trunk of left facial nerve.Exposure of the right facial nerve without nerve transection was used as the control.Rats were sacrificed at 3,7,14 and 28 days after injury respectively(n =10),the brainstem containing facial nucleus were collected,the expression of P/Q,N,L,R-type calcium channel α1A,α1B,α1C and α1E subunits was examined by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR).Results:Immunohistochemistry results show that whereas α1A,α1E subunits levels did not vary compared with control group 3,7,14,28 days after injury(P ＞0.05),α1B and α1C subunits immunoreactivity decreased in the motoneurons after injury,a sharp decrease was detected at 14 days after injury(P ＜ 0.01),thereafter returned to the control level at 28 days after axotomy(P ＞0.05).The expression of α1B and α1C mRNA was down-regulated,especially 14 days after the injury(P ＜0.01),and then recovered to normal level at 28 days (P ＞ 0.05).In addition,there was no significant difference of α1A and α1E subunits and their correspoding mRNA between operated group and control group at all time points(P ＞ 0.05).Conclusion:VGCC is involved in facial nerve injury and down-regulation of N-type and L-type calcium channels may be one of the role.%目的:探讨大鼠面神经切断后面神经核运动神经元中电压门控性钙离子通道(VGCC)的表达变化.方法:用荧光染料Dil神经逆行示踪确定面神经核位置,并通过尼氏染色确认.建立大鼠面神经损伤模型,左侧为手术组行面神经主干切断,右侧为假手术组仅暴露面神经.于术后3、7、14、28 d取面神经核标本,免疫组织化学及逆转录聚合酶链式反应(RT-PCR)检测P/Q、N、L、R型钙离子通道α1A、α1B、α1C、α1E亚基的表达.结果:免疫组化:手术组α1B、α1C亚基阳性表达在术后3d开始降低,14 d达到最低(P＜0.01),28 d回升至对照组水平(P＞0.05),而α1A、α1E亚基阳性表达无明显变化(P＞0.05).RT-PCR:手术组α1B 、α1C亚基mRNA表达水平下降,14 d表达最弱(P＜0.01),28 d基本恢复至正常(P＞0.05),α1A、α1E亚基mRNA表达无显著变化(P＞0.05).结论:VGCC参与面神经损伤,N型和L型钙离子通道可能以下调方式发挥作用.