脑梗死后脑红蛋白的表达及其保护机制

Neuroglobin expression and its possible neuroprotective role after middle cerebral artery occlusion in rat

目的探讨脑梗死后缺血半暗带脑组织中脑红蛋白（NGB）表达与caspase-3、谷氨酸表达的关系及NGB在脑缺血中的表达规律和保护作用的机制。方法制作大鼠局灶性脑缺血模型（MCAO）,随机分为假手术对照组、脑缺血组和单克隆NGB抗体干预组、干预对照组、正常干预对照组,分别在不同时间点断头取脑,制作标本,作脑红蛋白、caspase-3和谷氨酸免疫组化染色。结果（1）与假手术对照组比较,缺血5min亚组可见NGB阳性细胞数开始上升,0.5h达到高峰（P〈0.01）,随后下降,至6h接近假手术组。缺血各组（除24h、72h外）之间两两比较,差异均有统计学意义（P〈0.01）;（2）与假手术对照组比较,缺血0.5h亚组大脑皮质与豆状核区细胞caspase-3阳性表达增多,6～24h达到高峰（P〈0.01）,72h时仍高于假手术对照组,缺血各亚组之间两两比较,差异均有统计学意义（P〈0.01）;（3）与假手术对照组比较,缺血各亚组大脑皮质与豆状核区细胞谷氨酸阳性表达缺血0.5h就已增多,且随时间的变化呈逐步增高的趋势,24～72h达到高峰（P〈0.01）,缺血各亚组之间两两比较,差异均有统计学意义（P〈0.01）;（4）NGB表达与caspase-3、谷氨酸表达均呈负相关关系（分别为r=-0.953,P〈0.01;r=-0.973,P〈0.01）;（5）干预对照组caspase-3、谷氨酸表达均上调（P〈0.01）。结论脑缺血后NGB在缺血周围半暗带区早期表达升高,随后下降,于6h后降至正常,具有调节caspase-3、谷氨酸表达的作用,这是NGB脑保护作用的可能机制。

Objective To investigate the regularity of neuroglobin（NGB） expression in focal cerebral ischemia and its possible roles in neuroprotection. Methods The rat model of middle cerebral artery occlusion （MCAO） was established, the male SD rats were randomly classified into sham operation group, cerebral ischemia group （CI） , interventional MoAb-NGB group （ Ⅳ）, interventional control groups（IVC） and normal interventional control groups （nIVC）. Rats were killed at different time, and specimens were taken. Serial sections were cut and stained in immunohistochemistry of NGB, caspase-3 and glutamic acid respectively. Results （1） Compared with sham operation group, the NGB expression ascended obviously at 5 minute of ischemia, reached its peak on 0.5 hour（P〈0. 01） and descended thereafter, reached the level of sham operation group after 6 hours. When compared among each subgroups of CI, there were significant differences （all P〈 0.01 ）. （2）When compared with sham operation group, the caspase-3 expression ascended obviously in ischemia penumbra at 0.5 hour, peaking on 24 hour（P〈0. 01） and being still higher than sham operation group at 72 hour. When compared among the subgroups of CI, there were significant differences（all P 〈 0.01 ）. （3） When compared with sham operation group, the glutamic acid expression ascended obviously in ischemia penumbra at 0.5 hour（P〈0.01） ,and peaking on 24-72 hour （P〈0.01）. When compared among the subgroups of CI, there were significant differences（all P〈 0. 01）. （4）The NGB expression was negatively correlated with caspase-3-positive cell number and glutamic acid-positive cell number （r=-0. 953, P〈0. 01; r= -0. 973, P〈0.0l respectively）. （5） The expressions of casapase-3 and glutamic acid in groups of Ⅳ increased significantly（all P〈0.01）. Conclusions NGB can regulate the expressions of caspase-3 and glutamic acid, it might be the possible mechanism of neuroprotective effect of NGB.