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

描述（由申请人提供）：在过去的50年里，脑血管痉挛被认为是蛛网膜下腔出血（SAH）后预后不良的主要原因。最近，这一观点受到了挑战，观察到血管收缩的成功逆转通常不会导致患者预后的改善。不否认血管痉挛的持久意义，有一个新兴的概念，即血管收缩以外的因素在sah后的病理生理和预后中也很重要，包括血脑屏障的破坏，炎症和细胞死亡途径的激活。由于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一个非常重要的原因，导致短期和长期的皮质功能障碍和迟发性认知障碍。我们最近发现了一个新的离子通道，即磺酰脲受体-1 （SUR1）调控的NC（Ca- ATP）通道，其激活与脑水肿和神经元细胞死亡的形成有关。我们之前的工作表明，该通道在缺血/缺氧的情况下上调。最近，我们发现这个通道在神经炎症的情况下也显著上调。在中度SAH大鼠模型中，迟发性血管痉挛可以忽略，但神经炎症可靠地产生，我们发现：(i) NC（Ca-ATP）通道的调控亚基SUR1和TRPM4在覆盖SAH的皮质区域的神经元、毛细血管和小静脉中显著上调；（ii） SUR1和TRPM4上调的皮质区也表现出强烈的TNF1上调、血管源性水肿和caspase-3活化；（iii） sah后用格列本脲或针对SUR1的反义寡脱氧核苷酸治疗可显著降低TNF1上调、血管源性水肿和caspase-3激活。在这项拨款中，我们计划了3个具体目标（SA）：（SA1）证明格列本脲改善SAH后的炎症和水肿，在SAH大鼠模型中保持神经元完整性并改善神经行为结果；（SA2）证明格列本脲的有益作用是通过抑制通道的两个亚基SUR1和TRPM4中的任何一个来复制的；（SA3）表明，sah后SUR1和TRPM4蛋白及mRNA的上调与NC（Ca-ATP）通道的功能相关。我们预计，上述实验的成功完成将为SAH诱导的皮层功能障碍提供新的分子见解，并将带来新的治疗方法，以防止经常困扰SAH患者的破坏性认知障碍。公共卫生相关性：蛛网膜下腔出血（SAH）导致水肿、神经元丧失和认知功能障碍，部分原因是SAH后血液毒性诱导的炎症独立于血管痉挛。通过啮齿动物SAH模型，我们发现NC（Ca-ATP）通道的分子亚基SUR1和TRPM4在SAH后显著上调。在本提案中，我们将使用大鼠SAH模型来确定NC（Ca-ATP）通道在SAH后病理生理中的重要作用。

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.