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Basic analysis for the role of Na+/Ca2+ exchanger on ischemic brain damage to establish new brain resusciataion method

基础分析Na/Ca2交换器对缺血性脑损伤的作用建立脑复苏新方法

基本信息

批准号：
18591724
负责人：
UTINO Hiroyuki
金额：
$ 2.43万
依托单位：
Tokyo Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

To investigate the mechanisms of ischemic neuronal cell death, we explored the planned experiments to focus on the relationship between the function of astrocytic Na+/Ca2+ exchanger and intracerebral Ca2+ dynamics, calcineurin/immunophilin cascade, and mitochondrial dysfunction based on Mitochondrial Permeability Transition(MPT) and also investigated the role of Na+/Ca2+ exchanger for the formation of ischemic neuronal cell death. We have used Na+/Ca2+ exchanger KO mouse(NCXKO) for our experiments.From our pathohistological analysis, NCXKO group did not show any protective effect in mice forebrain ischemia model. NCXKO mice hippocampal slice experiments showed the high intracellular Ca2+ level but not mitochondrial compared to wild group, however, Cyclosporin A also inhibited both the rise of intracellular and intramitochondrial Ca2+ as same as wild group. NCXKO group and wild group showed no significant difference in terms of mitochondrial swelling and calcium retension capacity(CRC) due to Ca2+ overlaod.Respiratory control ratio(RCR) in NCXKO mice showed high oxygen consumption at state 3. From our results, we could speculate the reason why we could not get neuroprotectio is that mice was not homozygous, so gene deletion was not enough to explore the neuroprotection. But from the results of hippocampal slice experiments, we considered that NCX is somehow deleted. Mitochondrial permeability transition was induced in both NCXKO and wild mice and these results suggested that NCX gene deletion does not affect the inhibition of mitochondrial dysfunction. We have speculated the reseason why oxygen consumption was high in NCXKO mice is that Ca2+ extrusion to extracellular space in NCXKO mice need long time compared to wild one, so mitochondria need to produce ATP consuming huge amount of oxygen. From our results, importance of Na+/Ca2+ exchanger was explored.

为了探讨缺血性神经元死亡的机制，我们在线粒体通透性转换（MPT）的基础上，探讨了星形胶质细胞Na+/Ca 2+交换功能与脑内Ca 2+动力学、钙调磷酸酶/亲免素级联反应和线粒体功能障碍之间的关系，并探讨了Na+/Ca 2+交换在缺血性神经元死亡形成中的作用。本实验采用Na ~+/Ca ~（2+）交换体基因敲除小鼠（NCXKO），从病理组织学分析，NCXKO组对小鼠前脑缺血模型无保护作用。NCXKO小鼠海马脑片实验显示，与野生组相比，细胞内Ca 2+水平升高，但线粒体内Ca 2+水平没有升高，而环孢素A也抑制了细胞内和线粒体内Ca 2+的升高，与野生组相同。NCXKO组和野生组在由于Ca 2+过度负荷引起的线粒体肿胀和钙保持能力（CRC）方面没有显着差异。NCXKO小鼠的呼吸控制率（RCR）在状态3时显示高耗氧量。从我们的结果可以推测，我们不能获得神经保护的原因是小鼠不是纯合的，所以基因缺失不足以探索神经保护。但从海马脑片实验的结果来看，我们认为NCX可能存在某种缺失。在NCXKO和野生型小鼠中均诱导了线粒体通透性转换，这些结果表明NCX基因缺失不影响线粒体功能障碍的抑制。我们推测NCXKO小鼠耗氧量高的原因是NCXKO小鼠的Ca ~（2+）向细胞外的挤出时间比野生型长，线粒体需要消耗大量的氧来产生ATP。从我们的研究结果，Na+/Ca 2+交换的重要性进行了探讨。