脑缺血大鼠脑组织及血浆中microRNA-124a表达的变化

Expression changes of microRNA-124a in brain tissues and plasma in rats with cerebral ischemia

目的探讨microRNA-124a在脑缺血人鼠血浆和脑组织中表达的变化,以及其在正常大鼠不同组织和不同类型细胞中的分布。方法健康雄性SD大鼠35只,采用完全随机分组方法,3只用于检测microRNA-124a在正常大鼠各组织中的表达;候手术组、模型组各16只,其中每组8只用于检测造模前0 h和造模后2、4、8、12、24及48h血浆microRNA-124a表达,8只用于检测造模后24h缺血区脑组织micr0RNA-124a表达。采用线柃法制作大脑中动脉水久性闭塞模型,实时荧光定量PCR法(Real-time PCR)和逆转录聚合酶链应法(RT-PCR)检测microRNA-124a的表达。结果①microRNA-124a在大鼠恼、主动脉、肺、肝、心、脾、肌肉及肾脏中表达量依次降低,脑中的表达量足肾的1116.68(451.94～2740.08)倍,而主动脉是肾脏的12.81(6.72～24.42)倍;在大鼠海马神经元、小胶质细胞中的表达量分别是小鼠脑做血管内皮细胞的1031.12(501.50～2120.20)和19.43(13.20～28.60)倍。②与造模前比较,模型组大鼠血浆中microRNA-124a表达量在造模后8h开始升高(P=0.02);24h达高峰(P=0,008),约为造模前的18倍,随后逐渐下降,但48h表达量仍然高于造摸前(P=0.03)。假手术组大鼠血浆中microRNA-124的表达在造模前、后不同时间点差异均无统计学意义。③造模后24 h,模型组缺血区脑组织中microRNA-124a表达量明显降低,约为假手术组的12%～28%。结论 microRNA-124a特异性表达于大鼠脑神经元中。脑缺血24 h后,血浆中microRNA-124a表达量显著增高,而脑组织中表达最显著减少,机制可能与脑损伤造成microRNA-124a大量释放入血有关。

Objective To investigate the expression changes of microRNA-124a in plasma and brain tissues in rats with cerebral ischemia and its distribution in different tissues and different ceils in rats. Methods Thirty-five healthy male SD rats were randomized into 2 groups, the sham operation group and the model group （n = 16 in each group） , 8 rats in each group were used to detect the expression of plasma microRNA-124a at before the modeling and at 2, 4, 8, 12, 24, and 48 hours after the modeling. Eight rats were used to detect the expression of plasma microRNA-124a at 24 hours in ischemic brain tissue; Three rats were used to detect the expression of microRNA-124a in different tissues in normal rats. A model of permanent middle cerebral artery occlusion was induced by the intraluminal suture method. Real-time quantitative PCR assay and reverse transcription polymerase chain reaction （RT-PCR） were used to detect the expression of microRNA-124a. Results （1）The expression levels of microRNA-124a in brain, aorta, lung, liver, heart, spleen, muscle and kidney in rats were decreased successively, and the expression level in brain was 1116.68 （451.94 - 2740.08） times of the kidney. The expression levels of microRNA-124a in hippocampal neurons and microglia cells in rats were 1031.12 （501.50 -2120.20） and 19.43 （13.20 to 28.60） times those in brain microvascular endothelial cells in mice. （2）Compared to before modeling, the expression level of microRNA-124a in plasma began to increase at 8 hours after modeling （P = 0.02）. It reached the peak at 24 hours （P = 0. 008） , and it was about 18 times before modeling. Then it decreased gradually, but the expression level at 48 hours was still higher than that at 0 hour before modeling （ P =0.03）. There were no significant differences in the expression of microRNA-124 at different time points before and after modeling in the sham operation group. （3）rhe expression level of microRNA-124 in ischemic brain tissue in the model group was decreased significantly at 24 hours after modeling. It was about 12% to 28% of the sham operation group. Conclusion microRNA-124a specifically expressed in brain neurons in rats. The expression level of microRNA-124a in plasma was increased significantly at 24 hours after cerebral ischemia, while the expression level in brain tissue was decreased significantly. The mechanism may be associated with the brain damage caused a large quantity of microRNA-124a releasing into blood.