Pathological role of the SUR1-regulated NC(Ca-ATP) channel in cortex after subara

描述(申请人提供)：在过去的50年里，脑血管痉挛一直被认为是蛛网膜下腔出血(SAH)后预后不佳的主要原因。最近，这一想法受到了挑战，因为有观察到血管收缩的成功逆转通常不会带来患者预后的改善。在不否认血管痉挛的持久意义的情况下，出现了一个新的概念，即血管收缩以外的因素在SAH后的病理生理和预后中具有重要作用，包括血脑屏障的破坏，以及炎症和细胞死亡途径的激活。血液毒性引起的炎症可能是SAH后水肿形成和神经元丢失的重要原因，导致短期和长期的皮质功能障碍和延迟性认知功能障碍。我们最近发现了一种新的离子通道，即由磺脲受体-1(SUR1)调节的NC(Ca-ATP)通道，它的激活与脑水肿和神经细胞死亡有关。我们以前的工作表明，在缺血/缺氧的背景下，该通道被上调。最近，我们发现，在神经炎症的背景下，这一通道也显著上调。在中度SAH大鼠模型中，延迟性血管痉挛可以忽略不计，但可以可靠地产生神经炎症，我们发现：(I)在SAH覆盖的皮质区域，NC(Ca-ATP)通道的调节和造孔亚单位SUR1和TRPM4显著上调；(Ii)SUR1和TRPM4上调的皮质区域也显示出强烈的TNF1上调、血管源性水肿和caspase-3激活；(Iii)SAH后应用优降糖或针对SUR1的反义寡核苷酸显著减少F1表达、血管源性水肿和aspase-3激活。在这项拨款中，我们计划有三个特定的目标(SA)来：(SA1)证明格列本脲减轻SAH后的炎症和水肿，它维护神经元的完整性，并改善SAH大鼠的神经行为结局；(SA2)证明格列本脲的益处可以通过抑制该通道的两个亚单位SUR1和TRPM4中的任何一个来复制；(SA3)证明SAH后SUR1和TRPM4蛋白和mRNA的上调与功能NC(Ca-ATP)通道有关。我们预计，拟议实验的成功完成将为SAH诱导的皮质功能障碍带来新的分子见解，并将导致新的治疗方法，以防止经常困扰SAH患者的毁灭性认知障碍。公共卫生相关性：蛛网膜下腔出血(SAH)导致水肿、神经元丢失和认知功能障碍，部分原因是SAH后血液毒性诱导的炎症，而不是血管痉挛。利用SAH的啮齿动物模型，我们发现在SAH后，Nc(Ca-ATP)通道的分子亚基SUR1和TRPM4显著上调。在这个方案中，我们将使用SAH的大鼠模型来建立NC(钙-ATP)通道在SAH后病理生理学中的重要作用。

DESCRIPTION (provided by applicant): During the last 5 decades, cerebral vasospasm has been thought to be the principal cause of poor outcome following subarachnoid hemorrhage (SAH). Recently, this idea has been challenged by the observation that successful reversal of vasoconstriction often does not result in concomitant improvement in patient outcome. Without denying the enduring significance of vasospasm, there is an emerging concept that factors other than vasoconstriction are important in the pathophysiology and prognosis post-SAH, including disruption of the blood-brain barrier, and activation of inflammatory and cell death pathways. Inflammation due to the toxic nature of blood is likely to be a very significant cause of edema formation and neuronal loss post-SAH, resulting in short-term and long-term cortical dysfunction and delayed cognitive impairment. We recently discovered a new ion channel, the sulfonylurea receptor-1 (SUR1)-regulated NC(Ca- ATP) channel, whose activation is associated with formation of cerebral edema and neuronal cell death. Our previous work demonstrated that this channel is upregulated in the context of ischemia/hypoxia. Recently, we discovered that this channel is also prominently upregulated in the context of neuroinflammation. Using a rat model of moderate SAH, in which delayed vasospasm is negligible but neuroinflammation is reliably produced, we found that: (i) the regulatory and the pore-forming subunits of the NC(Ca-ATP) channel, SUR1 and TRPM4, are prominently up-regulated in neurons, capillaries and venules in cortical regions with overlying SAH; (ii) cortical regions that show up-regulation of SUR1 and TRPM4 also show strong TNF1 upregulation, vasogenic edema and caspase-3 activation; (iii) post-SAH treatment with glibenclamide or with anti-sense oligodeoxynucleotide directed against SUR1 significantly reduces TNF1 upregulation, vasogenic edema and caspase-3 activation. In this grant, we plan 3 specific aims (SA) to: (SA1) demonstrate that glibenclamide ameliorates post-SAH inflammation and edema, that it preserves neuronal integrity and improves neurobehavioral outcome in a rat model of SAH; (SA2) demonstrate that the beneficial effects of glibenclamide are replicated by gene suppression of either of the two subunits of the channel, SUR1 and TRPM4; (SA3) demonstrate that up-regulation of SUR1 and TRPM4 protein and mRNA post-SAH is associated with functional NC(Ca-ATP) channels. We anticipate that successful completion of the proposed experiments will yield novel molecular insights into SAH-induced cortical dysfunction, and will lead to new therapeutic approaches to prevent the devastating cognitive impairments that so often afflict SAH patients. PUBLIC HEALTH RELEVANCE: Subarachnoid hemorrhage (SAH) results in edema, neuronal loss and cognitive dysfunction attributable in part to post-SAH hemotoxicity-induced inflammation independent of vasospasm. Using a rodent model of SAH, we discovered that SUR1 and TRPM4, the molecular subunits of the NC(Ca-ATP) channel, are prominently up-regulated post-SAH. In this proposal, we will use a rat model of SAH to establish the essential role of the NC(Ca-ATP) channel in pathophysiology post-SAH.