液压冲击脑损伤大鼠海马BDNF mRNA表达实验研究

目的：研究脑损伤后脑脑源性神经营养因子（BDNF）mRNA表达及其时序性变化，进一步研究脑损伤的分子机制。方法：用免疫组织化学及原位杂交方法，观察液压冲击脑损伤大鼠海马BDNF mRNA受伤后不同时间（5、15、30分钟和1、3、6、12小时及1、3、7日）的表达情况，以正常大鼠及手术大鼠作为对照。结果：正常及手术对照组大鼠脑组织海马表达少量的BDNF；脑损伤后1小时海马齿状回CA2及CA3细胞表达增强，3－6小时达高峰，12小时开始下降，24小时后降至对照水平。1、3、6和12小时与正常及手术对照组比较均有显著性差异。结论：液压冲击脑损伤可诱导BDNF基因的表达，BDNF mRNA表达存在时间差异，提示机体对脑损伤存在自身保护机制。

The expression of brain derived neurotrophic factor mRNA in rats after fluid percussion brain injury

Objective:To investigate the pattern of changes in brain derived neurotrophic factor(BDNF) expression in experimental brain injury for further ascertaining the molecular mechanism of brain injury.Methods:Moderate severity of brain injury (0.2 MPa) was established in rats by the fluid percussion method.The animals were divided into normal control,operation sham control and experimental groups.Immunohistochemistry ABC method and in situ hybridization were used to determine the immunoreactivity and mRNA expression of BDNF.Results:Unilateral fluid percussion brain injury induced a bilateral increase in BDNF levels.The immunoreactivity and mRNA of BDNF elevated in the dentate gyrus as well as CA2 and CA3 regions of hippocampus at one hour after brain injury,peaking at 36 hours and declining to normal range 24 hours later.Significant differences in gene expression of BDNF were found between the 1,3,6 and 12 hours subgroups of the experimental group and both normal and operation sham controls.Conclusions:The results demonstrated that the brain injury could induce the gene expression of BDNF.The pattern of BDNF changes was quite regular,showing that there exists a selfprotective mechanism for host against injury.