Sigma Receptor Signaling in Focal Ischemia

局灶性缺血中的 Sigma 受体信号传导

• 批准号: 6825310
• 负责人: JEFFREY R KIRSCH
• 金额: $ 24.73万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6825310
• 关键词: BCL2 gene /protein; G protein; apoptosis; artery occlusion; autoradiography; biological signal transduction; brain disorder chemotherapy; brain injury; cerebral ischemia /hypoxia; dehydroepiandrosterone; drug receptors; enzyme linked immunosorbent assay; excitatory aminoacid; gene expression; in situ hybridization; laboratory rat; microdialysis; neuroprotectants; nitric oxide synthase; piperidine; radioimmunoassay; reperfusion; terminal nick end labeling; western blottings

During the past five years we have demonstrated that pharmacologic activation of sigma1 receptors greatly ameliorates the natural process of brain injury following transient focal ischemia. In addition, it is known that neurologic deterioration of aging, may be at least partially result from the natural reducation in endogenous hormones (e.g. DHEA) that are known to be agonists of the sigma1 receptor. Our previous work demonstrates that systemic administration of sigma1-receptor agonists improve outcome from experimental stroke, even when these agents are administered after the onset of reperfusion. In addition, we demonstrated that sigma1receptor agonists interfere with a primary mechanism of ischemic brain injury (NMDA receptor mediated NO toxicity). The overall goal of the current proposal is to test the hypothesis that sigma1receptor agonists cause neuroprotection by acting at sigma1receptors and interfering with specific parallel mechanisms of brain injury. Aim 1 will use cell culture techniques to determine the mechanism by which sigma1 receptors agonists interfere with NMDA induced NO production. The hypothesis to be tested is that the prototypic sigma1 receptor agonist PPBP indirectly impairs binding of NMDA to its receptor and does not have a direct effect on subsequent steps in the signal transduction pathway. Regardless of the exact site of action, since some sigma1 receptor agonists have been demonstrated to work through G-protein mechanisms, aim 2 will characterize the role of G-protein in basal and post-ischemic sigma1 receptor signaling mechanisms. The hypothesis is that PPBP impairs NMDA-stimulated NOS activity via a mechanism that involves a G-protein. As a parallel pathway we will also evaluate whether systemic administration of PPBP will impact the occurance of apoptosis. To this end aim 3 will test the hypothesis that PPBP administration is associated with increased bcl-2 and bcl-x-1 and decreased expression of bax in ischemic borderzones. Aim 4 will assess the therapeutic efficacy of endogenous hormones that are known to be agonists of the sigma1 receptor. We will test the hypothesis that the therapeutic efficacy of DHEA following transient focal ischemia is linked to decreased production of NO and can be blocked by specific sigma1 receptor antagonists. Aim 5 is designed to determine the mechanism for protection when the sigma1 receptor agonist is administered at the time of reperfusion. We will test the hypothesis that that delayed administration of PPBP during reperfusion from focal ischemia is associated with decreased expression of iNOS via a mechanism that is blocked by administration of a sigma1 receptor antagonist.

在过去的五年中，我们已经证明，Sigma1受体的药理激活极大地改善了短暂性局灶性缺血后脑损伤的自然过程。此外，众所周知，衰老的神经系统恶化至少是由于内源激素（例如DHEA）的自然还原而至少是由于已知是Sigma1受体激动剂的自然还原。我们以前的工作表明了系统管理 Sigma1受体激动剂的激动剂可以改善实验中风的结果，即使在再灌注后给予这些药物。此外，我们证明了SigMA1受体激动剂会干扰缺血性脑损伤的主要机制（NMDA受体介导的NO毒性）。当前建议的总体目标是检验以下假设：Sigma1受体激动剂通过对SigMA1受体作用并干扰脑损伤的特定平行机制引起神经保护作用。 AIM 1将使用细胞培养技术来确定Sigma1受体激动剂干扰NMDA诱导无生产的机制。要检验的假设是，原型Sigma1受体激动剂PPBP间接损害了NMDA与其受体的结合，并且对 信号转导途径的后续步骤。无论采取确切的作用位点，由于已经证明了一些Sigma1受体激动剂通过G蛋白机制起作用，因此AIM 2将表征G蛋白在基底和缺血后Sigma1受体信号传导机制中的作用。假设是PPBP会损害NMDA刺激的 通过涉及G蛋白的机制NOS活性。作为平行途径，我们还将评估系统性施用PPBP是否会影响凋亡的发生。为此，目标3将检验以下假设：PPBP给药与Bcl-2和Bcl-X-1的增加有关，并且在缺血性边界区域中BAX的表达降低。 AIM 4将评估内源性激素的治疗​​功效，后者已知是SIGMA1受体的激动剂。我们将检验以下假设：瞬时局灶性缺血后DHEA的治疗功效与NO的产生降低有关，并且可以通过特定的SIGMA1受体拮抗剂阻止。 AIM 5旨在确定Sigma1受体激动剂在再灌注时给药时的保护机制。我们将检验以下假设：抑制局灶性缺血再灌注过程中PPBP的施用与通过施用Sigma1受体拮抗剂阻止的iNOS表达降低有关。