大鼠液压冲击脑损伤BDNF及其受体TrkB表达的实验研究

目的研究脑损伤后BDNF及其受体TrKB蛋白表达及其时序性变化,进一步研究脑损伤的分子机制及法医学脑损伤时间推断.方法用免疫组织化学方法,观察液压冲击脑损伤大鼠BDNF及其受体TrKB蛋白在受伤后不同时间(5min、15min、30min、1h、3h、6h、12h、1d、3d、7d)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表达少量的BDNF及TrKB;脑损伤后1h大脑皮质颗粒和锥体细胞、海马CA3及小脑Purkinje细胞表达增强,3h达高峰,维持较高水平,12h开始下降,24h后降至对照水平.1h、3h、6h和12h与正常及手术对照组比较均有显著性差异.结论表明脑损伤可诱导BDNF及TrKB基因在脑内表达,其时序性改变可望用于法医学脑损伤时间推断.

A study of BDNF and TrKB in rat brain after fluid percussion injury by the immunohistochemistry

Objective Study on the pattern of changes of BDNF and it's receptor TrKB occurred in the experimental brain injury model for further ascertaining the molecular mechanism of brain injury. Methods Three groups were settled, including: normal control, operation sham control and experimental group. Moderate severity of brain injury (0.2MPa) was established by the fluid percussion method. In the later case, 10 subgroups were divided,: 5 rats each group. Immunohistochemistry ABC method was used for studying the immuno-reactivity of both BDNF and TrkB factors. Results Unilateral FP brain injury induced a bilateral increasing in levels of both BDNF and TrK B factors.The immuno-reactivity of both BDNF and TrKB factors increased in granule and pyramidal layers in cortex, CA3 regions of hippocampus as well as the Purkinje neurons of cerebellum 1h after brain injury, reached to the peak at 3-6h, remained above normal level up to 12h and then declined to normal control level at 24h after brain injury. Significant difference in gene expression of both BDNF and TrkB were found between the 1h, 3h, 6h and 12h subgroups of experimental groups and both normal and operation sham control groups. Conclusion The results demonstrated that the brain injury induced the gene expressions not only the IEGs, but also both BDNF and it's receptor TrKB. The pattern of BDNF and TrKB level changes were quite regular which might be used for timing of injury in forensic medicine aspect. The role of these two factors in molecular mechanism of brain injury has been discussed.