微管相关蛋白和NF-KB在大鼠脑缺血预处理中的神经保护作用

目的探讨微管相关蛋白（doublecortin）和NF—KB在脑缺血预处理后介导的神经保护作用。方法取清洁级雄性6周龄Wistar大鼠54只，按数字法随机分为缺血组、缺血预处理组、假手术组，每组各18只；再按三个观察时间分为24、48、72h组，每个时间点各6只。对缺血预处理组的大鼠，先行左颈内动脉暂时性血流阻断，同时以0．25mL／min的速度，从左颈外动脉处输入等渗盐水，3min后恢复血流，停止输液7min，共重复3次。3d后，再与缺血组同时采用大脑中动脉线栓法，建立局灶性脑缺血损伤模型；对假手术组大鼠仅分离颈总动脉。在术后相应时间点评价大鼠的神经行为、实时荧光定量PCR检测其脑组织中doublecortinmRNA和NF—KBmRNA的表达。结果①缺血预处理组大鼠在24、48、72h的神经功能缺损评分与缺皿组比较，差异有统计学意义（P〈0．05）。②同一时间点各组间比较：doublecortinmRNA和NF—KBmRNA表达，两缺血组均高丁假手术组，预处理组的doublecortinmRNA又高于缺血组；预处理组的NF—KBmRNA则低于缺血组，均P〈0．01。③动态比较：doublecortinmRNA表达随时间延长而增加，NF—KBmRNA则随时间延长而降低，均P〈0．01。结论脑缺血损伤可诱导一定程度的doublecortin的表达和NF—KB信号通路的激活。缺血预处理可能通过上调doublecortin和下调NF—KB的表达，促进神经细胞再生，介导神经保护效应。

Neuroprotective effects of doublecortin and NF-kappa B on the cerebral ischemic preconditioning in rats

Objective To investigate the neuroprotective effects of doublecortin and NF-kappa B （NF-KB） on the cerebral ischemic preconditioning in rats. Methods A total of fifty-four 6-week -old Wistar male rats were randomly assigned to 3 groups by digital method： the ischemic, the ischemic precon- ditioning and the sham operation groups （ n = 18 in each group）. Then they were redivided according to 3 observation time points： 24-, 48-, and 72-hour groups （n = 6 at each time point）. The blood flow of left internal carotid arteries of the rats was temporarily blocked in the ischemic preconditioning group. At the same time, the isotonic saline was infused into the left external carotid arteries with the speed of 0.25 mL/min. The blood flow was restored after 3 minutes, the infusion was stopped for 7 minutes, and this was repeated for 3 times. Three days latter, the middle cerebral artery intraluminal suture method was used to induce a focal ischemie injury model with the ischemic group at the same time. The common carotid arteries were separated only in rats of the sham operation group. At the corresponding time points alter procedure, the neurobehavioral of rats was evaluated, a real-time quantitative PCR was used to detect the expression of doublecortin mRNA and NF-KB mRNA in brain tissue. Results ①There was significant difference in the neurological deficit scores at 24, 48, and 72 hours at the same time points between the ischemic preconditioning group and the ischemic group.② Compared to all the groups at the same time points ： The expression of doublecortin mRNA and NF-KB mRNA in 2 ischemic groups was higher than that in the sham operation group; and the expression of doublecortin mRNA in the ischemie preconditioning group was higher than that in the ischemic group; the expression of NF-KB mRNA was lower than that in the isehemic group （ P 〈 0.01 ）. ③Dynamic comparison ： The expression of doublecortin mRNA increased with time, but that of NF-KB mRNA decreased with time （ P 〈 0. 01 ）. Conclusion Cerebral ischemic injury may induce a certain degree of doublecortin expression and activate the NF-KB signal pathway. Ischemic preconditioning may promote nerve cell regeneration and mediate neuroprotective effects by upregnlating the doublecortin expression and down regulating the NF-KB expression.