SIGMA RECEPTOR SIGNALING IN FOCAL CEREBRAL ISCHEMIA

兴奋性氨基酸是缺血性脑损伤的重要组成部分 机械装置。因为Sigma受体配体调节神经元的反应 药物对N-甲基-D-天冬氨酸受体的体外刺激作用 通过特定的Sigma配体识别位点，它们具有潜力 在中风中的治疗价值，可能与之无关 限制其临床应用的不良副作用 NMDA受体拮抗剂 4-苯基-1-(4-苯基丁基)哌啶(PPBP)是一种典型的异构体。 提供神经保护的受体配体，但其确切机制是 以前还没有在体内诱导出保护作用。中得出的结论 体外实验表明，Sigma受体配体可能会干扰 通过与兴奋性氨基酸相互作用引起的神经毒性 NMDA受体复合体。此外，Sigma受体配体可以有利地 减少兴奋性神经递质和儿茶酚胺的释放 缺血，特别是谷氨酸和多巴胺。这个项目的总体目标是 项目是定义体内信号传递过程，这一过程解释了 Sigma受体配体在短暂性脑缺血发作中的显著神经保护作用 局灶性缺血。一般的假设是，这些配体保护 通过独特的Sigma受体途径抑制兴奋性毒素 释放和NMDA激活，从而阻止随后的神经元 一氧化氮合酶(NNOS)激活与细胞死亡。具体目标 威尔：定义最有效的治疗范式--西格玛受体 配体PPBP在短暂性局灶性脑缺血中的作用；确定Sigma受体 激活抑制局灶性脑缺血损伤的兴奋性毒性机制； 表征基础和缺血后Sigma受体信号转导机制 在体内；确定Sigma受体是否介导了 神经保护是一氧化氮合酶构成的神经元亚型所特有的。 该方法将包括使用血管内线闭塞 大鼠和小鼠短暂性局灶性脑缺血模型， 微透析法测定自发和NMDA刺激的一氧化氮合酶活性， ITS微透析法测定兴奋性氨基酸和多巴胺 代谢物，免疫化学检测G蛋白和 Sigma受体分布的放射自显影测量。这些 各种技术结合起来检验了Sigma受体配体 通过以下方式改善神经学结果(组织学和神经功能) 缺血和缺氧时对兴奋性氨基酸机制的干扰 通过G蛋白第二信使再灌流，所有这些最终 导致NO生成减少，脑损伤减轻。

Excitatory amino acids are an integral part of ischemic brain injury mechanisms. Because sigma-receptor ligands modulate neuronal responses to pharmacologic N-methyl D-aspartate (NMDA) receptor stimulation in vitro via a specific sigma ligand recognition site, they are of potential therapeutic value in stroke and may not be associate with the same spectrum of undesired side-effects which limit the clinical utility of NMDA receptor antagonists 4-phenyl-1-(4-phenylbutyl) piperidine (PPBP) is a prototypic sigma- receptor ligand which provides neuroprotection but the exact mechanism of protection has not been previously elicited in vivo. Conclusions from in vitro experiments have suggested that sigma-receptor ligands may interfere with excitatory amino acid-induced neurotoxicity by interacting with the NMDA receptor complex. Further, sigma-receptor ligands may advantageously decrease excitotoxic neurotransmitter and catecholamine release during ischemia, specifically glutamate and dopamine. The overall goal of this project is to define the in vivo signaling process that accounts for the marked neuroprotective properties of sigma-receptor ligands in transient focal ischemia. The general hypothesis is that these ligands protect the brain by a unique sigma-receptor pathway which inhibits excitotoxin release and NMDA activation, and, therefore, prevents consequent neuronal nitric oxide synthase (nNOS) activation and cell death. The specific aims will: define the most efficacious treatment paradigm sigma-receptor ligand, PPBP, in transient focal ischemia; determine if sigma-receptor activation inhibits excitotoxic mechanisms of focal ischemic brain injury; characterize basal and post-ischemic sigma-receptor signaling mechanisms in vivo; determine if sigma receptor mediated mechanisms of neuroprotection are specific to the constitutive neuronal isoform of NOS. The methodology will include use of an intravascular thread occlusion model of transient focal ischemia in rodents (both rats and mice), microdialysis measurement of spontaneous and NMDA-stimulated NOS activity, microdialysis measurement of excitatory amino acids and dopamine with its metabolites, immunochemistry for detection of G-protein and autoradiography for measurement of sigma-receptor distribution. These techniques are combined to test the hypothesis that sigma-receptor ligands improve neurologic outcome (histology and neurologic function) by interfering with excitatory amino acid mechanisms during ischemia and reperfusion through a G-protein second messenger, all which ultimately result in decreased production of NO and decreased brain injury.