miR-9在阿魏酸钠改善缺氧缺血性脑损伤大鼠学习记忆中的作用

目的:探讨miR-9在阿魏酸钠(SF)改善缺氧缺血性脑损伤新生大鼠学习记忆中对海马神经元NMDAR1和NgR1的调节作用。方法:88只7日龄SD大鼠随机分为假手术组(sham)、缺氧缺血性脑损伤组(HIBD)、阿魏酸钠治疗组(HIBD+SF)、miR-9抑制组(HIBD+LNA-miR-9),每组各22只。假手术组仅分离左侧颈总动脉,其余组结扎左侧颈总动脉进行缺氧后制作HIBD模型。于21日龄,阿魏酸钠治疗组连续5 d腹腔注射阿魏酸钠,miR-9抑制组经左侧脑室注射一次LNA-miR-9。于30日龄行Morris水迷宫检测各组大鼠空间学习记忆能力。于26日龄,real time RT-PCR检测各组大鼠左侧海马神经元miR-9、NMDAR1mRNA和NgR1mRNA的表达,Western Blot检测NMDAR1和NgR1蛋白的表达。结果:Morris水迷宫实验显示:与假手术组比较,HIBD组逃避潜伏期延长(P<0.05)、在目标象限逗留时间缩短(P<0.05);阿魏酸钠治疗组、miR-9抑制组较HIBD组均有逃避潜伏期缩短(P<0.05)、在目标象限逗留时间延长(P<0.05)。real time RT-PCR、Western Blot检测显示:HIBD组NMDAR1和NgR1的mRNA和蛋白表达以及miR-9表达较假手术组均明显上调(P<0.05);阿魏酸钠治疗组、miR-9抑制组较HIBD组各指标均明显下调(P<0.05)。结论:阿魏酸钠可能通过下调miR-9来抑制NMDAR1和NgR1的表达从而改善缺氧缺血大鼠的学习记忆能力。

The role of miR-9 in the improvement of learning and memory ability of rats with hypoxic-ischemic brain damage by sodium ferulate

Objective:To investigate the regulatory effect of miR-9 on NMDAR1 and NgR1 of hippocampal neurons in the process of sodium ferulate improving learning and memory ability of neonatal rats with hypoxic-ischemic brain damage(HIBD).Methods:887-day-old SD neonatal rats were randomly divided into sham group(sham),hypoxic-ischemic brain damage group(HIBD),sodium ferulate treatment group(HIBD+SF),and miR-9 inhibition group(HIBD+LNA-miR-9),with 22 rats in each group.HIBD model was established by the ligation of left common carotid artery and hypoxia in rats,while,the rats in sham group just underwent the isolation of left common carotid artery without ligation and hypoxia.At postnatal day 21(P21),sodium ferulate was intraperitoneally injected for 5 consecutive days in sodium ferulate treatment group,while rats from miR-9 inhibition group were administered left intracerebroventricular injection of LNA-miR-9.Subsequently,Morris water maze was performed to test the spatial learning and memory ability of rats at P30 days.Finally,the expressions of miR-9,NMDAR1mRNA and NgR1mRNA of the left hippocampus were detected by real time RT-PCR,and the protein expressions of NMDAR1 and NgR1 were detected by Western Blot in each group of rats at P26 days.Results:Morris water maze test showed that the escape latency of HIBD group was longer(P<0.05)and the duration of stay in the target quadrant was shorter(P<0.05)than that of sham group,while,in the HIBD rats after sodium ferulate or LNA-miR-9 treatment,the escape latency was shortened(P<0.05)and the duration of stay in the target quadrant was prolonged(P<0.05).Moreover,real time RT-PCR and Western Blot showed that the mRNA and protein expressions of NMDAR1 and NgR1 as well as the expression of miR-9 in HIBD group were significantly higher than those in sham group(P<0.05),while,the above indicators were visibly decreased in the HIBD rats after sodium ferulate or LNA-miR-9 treatment(P<0.05).Conclusion:Sodium ferulate may inhibit the expressions of NMDAR1 and NgR1 by down-regulating the expression of miR-9,thus improving the learning and memory ability of hypoxic-ischemic rats.