脑损伤大鼠运动皮质BDNF的表达变化

目的观察创伤性脑损伤(TBI)大鼠脑组织运动皮质脑源性神经营养因子(BDNF)表达变化并探讨其与神经行为学的关系。方法成年SD大鼠分假手术对照组和自由落体脑外伤组(TBI组),每组13只。TBI后1、3、8、13d分别进行大鼠神经功能缺损评分(NSS)。术后7d处死大鼠,取损伤处脑组织行RT-PCR检测BDNFmRNA表达;术后13d处死大鼠,取损伤处脑组织行免疫组化和原位杂交检测BDNF表达。结果 TBI后大鼠神经行为明显受损,NSS评分较假手术组增加(P<0.05),但随时间延长NSS评分有所下降(P<0.05)。RT-PCR结果显示,BDNF mRNA表达水平TBI组和假手术组差异无统计学意义(P>0.05)。免疫组化和原位杂交染色结果显示,BDNF蛋白和mRNA主要分布在皮质神经元,阳性细胞数量明显减少(P<0.05),而细胞内BDNF的光密度值则明显增加(P<0.05)。结论 TBI后大鼠神经功能有一定恢复,其机制可能与备用神经元内BDNF的表达水平上调有关。

Changes of BDNF expression in neurons in traumatic brain injury rats

Objective To investigate changes of brain derived neurotrophic factor(BDNF) expression in neurons in traumatic brain injury(TBI) rats.Methods Adult SD rats were divided into sham and operated group resulted from hammer fall contusion(30 cm high,50 g weight).Thirteen rats in each group were used.Some of animals(n=6 in each group) were used to perform immunohistochemistry and in situ hybridization,and the other(n=7) was used for RT-PCR.After NSS assessment was determined at 1,3,8,13 days,TBI rats were sacrificed,brain tissues were then harvested to measure BDNF level.Data were analyzed by using statistic method.Results A increased NSS scores(P<0.05) was observed after TBI,which implied the significant neurobehavioral changes in rats.But a gradual decreasing NSS scores(P<0.05) was also observed along with time prolonged.Severe neurological severity function was seen following TBI,and it presents a gradual improvement indicated by decreasing NSS scores,despite BDNF mRNA level in whole brain tissue did not present a significant change,the BDNF expression(indicated by optical density values analysis) in subcellular structure,known as neurons,exhibited a significant increase,when compared with that of sham group(P<0.05).This could simultaneously accompany with the decrease in the number of neurons in TBI rats.Conclusion TBI rats exhibit a neuroplasticity with the BDNF upregulation in neurons following injury.