脑创伤模型创伤区脑组织中miRNA-21的表达变化及意义

目的观察大鼠脑创伤模型创伤区脑组织中miRNA-21表达变化,探讨其与预后的关系。方法 196只大鼠随机分为假手术对照组（对照组）和创伤组,各98只。前者行头皮切开和磨除骨窗,保持硬膜完整,不进行打击;后者以液压打击法制作大鼠脑外伤模型后,分别在创伤后2、12、24、48、72 h和7、14 d行神经行为学评分,之后处死大鼠,取创伤区脑组织采用定量PCR检测miRNA-21,石蜡切片采用原位末端标记法（TUNEL法）行凋亡神经细胞染色并计数。采用Pearson积差相关检验分析miRNA-21表达水平与神经行为学评分和凋亡细胞的相关关系。结果对照组相当于创伤区脑组织中的miRNA-21表达并未随创伤时间的增加而变化。创伤组创伤区脑组织中miRNA-21表达随伤后时间延长而逐渐上升,于48 h达峰值,而后逐渐降至基础水平（P〈0.05）;神经行为学评分于48～72 h时升至最高而后逐渐恢复（P〈0.05）;凋亡的神经细胞计数于伤后72 h达高峰,而后逐渐减少,于伤后7～14 d稳定于一定水平（P〈0.05）。创伤组miRNA-21表达变化与神经行为学评分和凋亡的神经细胞呈正相关（r=0.430、0.411,P均〈0.01）。结论脑创伤模型创伤区脑组织中miRNA-21表达上调,其表达水平与脑创伤预后有关。

Expression and significance of miRNA-21 in the brain tissue of the model of traumatic brain injury

Objectiv To study the expression of miRNA-21 in the brain tissue of post traumatic brain injury（TBI）and explore the relationship between miRNA-21 and prognosis of TBI.Methods 196 wistar rats were assigned randomly to control group and TBI group（n=98,respectively）,and then they was further divided into 7 subgroups.They were examined at 2,12,24,48,72 h,and 7,14 d after post TBI neurological evaluations.The rats were sacrificed after evaluated by neural behavioral score.The expression miRNA-21 in cerebral tissue was detected by qRT-PCR methods,and neuronal apoptosis in cerebral cortex stained with terminal deoxynucleotide-transferase-mediated dUTP nick end labeling（TUNEL）.The correlations between expression miRNA-21 with neural behavioral score and neuronal apoptosis were calculated with Pearson＇s correlation test.Results The expression of miRNA-21did not increase over time along with changes in control group,increased in TBI group in 24 h after injured brain tissue.It reached the peak level at 48 h and then gradually declined to baseline（all P0.05）.The neural behavioral score reached the maximum in 48~72 h after injury,then gradually reduced to a stable level（P0.05）.The positive cells were not detected in the ipsilateral cortex of control group,but appeared within the first 24 h after injury and peaked at 72 h（P0.05）.It was positively correlated the expression of miRNA-2 with neural behavioral score and apoptosis of nerve cells（r=0.430,0.411,all P0.01）.Conclusions The expression of miRNA-21 is increased in cerebral tissue after TBI.Its expression level and prognosis of TBI are interrelated.