Matsuyama T, Shimizu S, Nakamura H, Michishita H, Tagaya M, Sugita M
Fifth Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan.
Stroke. 1994 Jul;25(7):1417-23; discussion 1424. doi: 10.1161/01.str.25.7.1417.
We reported that recombinant human superoxide dismutase ameliorates delayed neuronal death in the postischemic gerbil hippocampus. Since postischemic induction of copper-zinc superoxide dismutase messenger RNA was abolished by this treatment, oxygen radicals generated on reperfusion may induce the expression of this gene. In the present study we examined whether oxygen radicals also induce the expression of manganese superoxide dismutase messenger RNA in the postischemic brain.
We induced transient cerebral ischemia by occluding the bilateral common carotid arteries of gerbils. Recombinant human superoxide dismutase (8 x 10(5) U/kg) or apo-superoxide dismutase was administered intravenously 1 minute before a 5-minute occlusion of the carotid arteries. We analyzed both copper-zinc and manganese superoxide dismutase RNA by in situ hybridization histochemistry and by Northern and dot blot analyses using radioisotope-labeled oligonucleotide probes.
Hybridization with the manganese superoxide dismutase messenger RNA occurred at the limit of detection in normal CA1 neurons. We observed striking increases in the labeling of CA1 up to 24 hours after 5 minutes of ischemia. The hybridization occurred anew in glial cells of the CA1 layer during 3 to 7 days. Pretreatment with recombinant human superoxide dismutase had no effect on the postischemic induction of manganese superoxide dismutase messenger RNA, whereas the same treatment significantly attenuated (P < .01) the increase in copper-zinc superoxide dismutase messenger RNA.
Our results demonstrated temporal postischemic induction of manganese superoxide dismutase messenger RNA. The inducer may not be superoxide radicals but may be other chemical mediators such as cytokines.
我们曾报道重组人超氧化物歧化酶可改善缺血后沙鼠海马体中的迟发性神经元死亡。由于该治疗消除了缺血后铜锌超氧化物歧化酶信使核糖核酸的诱导，再灌注时产生的氧自由基可能诱导该基因的表达。在本研究中，我们检测了氧自由基是否也能诱导缺血后脑组织中锰超氧化物歧化酶信使核糖核酸的表达。
通过阻断沙鼠双侧颈总动脉诱导短暂性脑缺血。在颈动脉阻断5分钟前1分钟静脉注射重组人超氧化物歧化酶（8×10⁵U/kg）或脱辅基超氧化物歧化酶。我们通过原位杂交组织化学以及使用放射性同位素标记的寡核苷酸探针进行Northern印迹和斑点印迹分析，来分析铜锌和锰超氧化物歧化酶核糖核酸。
在正常CA1神经元中，与锰超氧化物歧化酶信使核糖核酸的杂交在检测极限水平出现。我们观察到缺血5分钟后直至24小时，CA1区的标记显著增加。在3至7天内，CA1层的胶质细胞中重新出现杂交信号。用重组人超氧化物歧化酶预处理对缺血后锰超氧化物歧化酶信使核糖核酸的诱导没有影响，而相同处理显著减弱（P<.01）了铜锌超氧化物歧化酶信使核糖核酸的增加。
我们的结果表明缺血后锰超氧化物歧化酶信使核糖核酸有暂时诱导现象。诱导物可能不是超氧自由基，而是其他化学介质，如细胞因子。
