大鼠弥漫性轴索损伤后海马Homer1蛋白各亚型的表达及意义

Expression and significance of Homer1 subtype protein after diffuse axonal injury in the hippocampus of rats

目的研究侧向旋转致大鼠脑弥漫性轴索损伤(DAI)后海马Homer1蛋白各亚型的表达规律及其意义。方法成年雄性SD大鼠95只,随机分为对照组(NC组,n=10)、假手术组(SOC组,n=10)和DAI组(n=70),DAI组又根据致伤后时间分为1、3、6、12、24、48、72h共7个亚组,应用侧向瞬时旋转的方法建立大鼠脑DAI模型,取海马组织分别行Homer1蛋白各亚型(Homer1a、Homer1b/c)的免疫组化染色、Western blotting和实时荧光定量RT-PCR检测。结果实验过程中5只动物死亡,其余90只进入结果分析。3种检测方法均发现DAI组神经组织中Homer1a蛋白和mRNA水平自伤后1h开始表达,至24h表达量最高(P<0.01),持续至72h仍维持较高水平(P<0.05),NC组该蛋白仅有极少量表达;而Homer1b/c在NC组、SOC组和DAI组均可见明确的阳性表达,但3组的表达量差异无统计学意义(P>0.05)。结论 Homer1a在DAI损伤急性期即于海马组织中表达,Homer1b/c则在损伤前后均有表达。Homer1蛋白的两种亚型可能在DAI中均发挥着要作用,抑制Homer1b/c或促进Homer1a表达可能对DAI损伤后神经元具有保护作用。

Objective To investigate the expression and significance of Homer1 subtype protein in the hippocampus after diffuse axonal injury（DAI） as a result of lateral rotation in rat.Methods Ninety-five adult male SD rats were randomly divided into the normal control（NC）,sham-operated control（SOC）,and DAI groups.The DAI group was further subdivided into seven subgroups.The division of seven subgroups was based on the number of hours after injury,namely,1,3,6,12,24,48,and 72h（n=10）.Instantaneous lateral rotation was used to cause DAI in the present study.The hippocampus of the rats were harvested for immunohistochemical staining,Western blotting,and quantitative RT-PCR determination of the Homer1 subtype protein（Homer1a and Homer1b/c）.Results Five rats died during the experiment,and the results of remaining 90 were analyzed.The three detection methods showed that Homer1a protein and mRNA in the nervous tissue in the DAI group started to express at 1 h after the injury.The expression reached the peak level at 24h（P〈0.01）,and maintained at a higher level until 72h（P〈0.05）.The expression of the protein was minimal in the NC group.In addition,the positive expression of Homer1b/c was clearly observed in the NC,SOC and DAI groups.However,there was no significant difference in the expression intensity among the three groups（P〈0.05）.Conclusion Homer1a was dynamically expressed in the hippocampus in the acute stage of DAI injury.Homer1b/c was expressed before and after injury.Two subtypes of Homer 1 protein may play an important role in DAI.Inhibition of Homer1b/c or the promotion of Homer1a expression may have protective effects on the neurons after DAI injury.