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目的探讨脑缺血再灌注后大鼠缺血中心区及周围区大脑皮质髓鞘相关的抑制分子Nogo-A及其受体NgR的mRNA和蛋白表达的变化规律及意义。方法采用线栓法制作大鼠脑缺血再灌注模型,分为假手术对照组、缺血2h再灌注6h、12h、24h、48h、72h、7d和14d组．通过HE染色进行病理观察,逆转录一聚合酶链反应(RT-PCR)的方法检测mRNA,免疫组织化学的方法检测蛋白表达,观察脑缺血再灌注后缺血中心区及周围区大脑皮质Nogo-A及其受体NgR的变化。结果Nogo-A mRNA及蛋白表达在缺血中心区6h即有下降(与对照组相比,P＜0．05),并随再灌注时间延长表达逐渐减少,24h降低最为明显并持续至14d；而缺血周边区,再灌注48h前无显著性变化．72h表达增加(与对照组相比,P＜0．05),7d增加更为显著,14d降至正常。NgR mRNA及蛋白表达在缺血中心区再灌注6h后开始下降(与对照组相比,P＜0．05),48h降低最为明显；而缺血周围区NgR mRNA及蛋白表达在各个时间点无显著变化(P＞0．05)。结论脑缺血后灶周Nogo-A mRNA及蛋白表达增加持续至再灌注后7d以上,针对其表达的规律进行干预可能成为脑梗死后改善轴突生长的有效措施；灶周NgR的表达无显著变化,显示Nogo-A的作用尚有其他受体介导。
Objective To investigate the changes of mRNA and protein expression of myelin-related inhibitory molecule Nogo-A and its receptor NgR in the cerebral cortex after cerebral ischemia and reperfusion in rats. Methods The rat model of cerebral ischemia-reperfusion was established by thread occlusion. The rats were divided into sham-operation control group, 6h, 12h, 24h, 48h, 72h, 7d and 14d after reperfusion for 2h. The pathological changes were observed by HE staining, mRNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR), protein expression was detected by immunohistochemical method. The cerebral cortex Nogo -A and its receptor NgR changes. Results The mRNA and protein expression of Nogo-A decreased at 6h after ischemia (compared with the control group, P <0.05), and gradually decreased with the prolongation of reperfusion. The decrease of Nogo-A mRNA was most obvious and continued until 14d. The ischemic border area, no significant change 48h before reperfusion. 72h expression (P <0.05 compared with the control group), 7d increased more significantly, 14d decreased to normal. NgR mRNA and protein expression began to decline 6h after reperfusion in the ischemic center (P <0.05 compared with the control group), and decreased most obviously at 48h. The expression of NgR mRNA and protein in ischemic peripheral areas had no significant difference at all time points Significant changes (P> 0.05). Conclusion The increase of Nogo-A mRNA and protein expression after focal cerebral ischemia lasts more than 7 days after reperfusion, and intervention on the expression of Nogo-A may be an effective measure to improve axonal growth after cerebral infarction. Variations show that there are other receptor-mediated effects of Nogo-A.