Mechanisms Regulating Cerebral Blood Flow

描述(由申请人提供)： 本PPG的目标是明确在正常和病理条件下(炎症、蛛网膜下腔出血(SAH)和反应性充血)下，细胞色素P450(CYP)脂肪酸代谢产物控制营养性脑血流(CBF)的机制。这笔赠款包括3个相互依赖的科学项目和2个核心(行政和生物化学/分子)，以支持和促进该计划中的研究。4年前，当这个项目第一次被资助时，CYP的花生四烯酸(AA)代谢产物，特别是环氧二十碳三烯酸(EETs)和20-羟基二十碳四烯酸(20-HETE)，通过调节离子通道活性在调节脑血管张力中发挥任何作用的概念是新的，受到了相当大的怀疑。然而，很大程度上由于这一计划的进展和大量文献的发表，大多数研究人员现在认为AA的CYP代谢物通过调节脑动脉K+通道活性在脑血管张力的自动调节、功能性充血和脑内血管生成中发挥重要作用。这项续展申请是在过去4年取得的显著进展和成就的基础上提出的。项目1将研究Hard博士和他的团队最近从大鼠脑中克隆和表达的CYP4F和4X亚型的性质、底物特异性和在AA和其他物质(DHA和LTB4)代谢中的作用。然后，他们将确定形成的代谢物对脑血管张力和脑部炎症的影响。由罗曼博士领导的项目2将探索20-HETE在大鼠SAH后脑血管张力调节中的作用。项目3将探索大脑中反应性高血症的独特假说的各个方面。Koehler和Gebremedhin博士将确定神经元释放的谷氨酸是否会刺激星形胶质细胞上的受体打开新的KC通道，并增加这些细胞中的电容性钙进入。他们认为，钙离子浓度的升高刺激星形胶质细胞合成和/或释放EETs，并通过开放这些细胞中的KCA通道来扩张邻近的脑血管。每个项目都将利用生化/分子核心对EETs、20-HETE进行LC/MS测量，并对其他CYP脂肪酸代谢物进行结构鉴定。此外，所有三个项目的工作都将通过与德克萨斯大学西南医学中心的法尔克博士达成的财团协议得到支持，法尔克博士将合成并提供抑制剂、激动剂和拮抗剂。这个项目反映了项目研究人员之间分享技术和想法的长期传统，并将极大地提高我们对CYP脂肪酸在控制健康和SAH后脑血流中的作用的理解。

DESCRIPTION (provided by applicant): The goal of this PPG is to define the mechanisms through which cytochrome P450 (CYP) metabolites of fatty acids control nutritive cerebral blood flow (CBF) under normal and pathologic conditions (inflammation, subarachnoid hemorrhage (SAH) and reactive hyperemia). The grant contains 3 interdependent scientific projects and 2 cores (administrative and biochemical/molecular) that support and facilitate the research in the program. When this program was first funded 4 years ago, the concept that CYP metabolites of arachidonic acid (AA), notably epoxyeicosatrienoic acids (EETs) and 20-hydroxyeicosatetraenoic acid (20-HETE), played any role in the regulation of cerebral vascular tone by regulating ion channel activity was novel and was met with considerable skepticism. However, largely because of the progress made in this program and the large number of publications generated, most investigators now believe that CYP metabolites of AA play an important role in the autoregulation of cerebral vascular tone, functional hyperemia and angiogenesis in the brain by regulating K+ channel activity in the cerebral arteries. This renewal application builds upon the outstanding progress and accomplishments made over the last 4 years. Project 1 will examine the properties, substrate specificity and role of CYP4F and 4X isoforms that Dr. Harder and his group recently cloned and expressed from the brain of rats on the metabolism of AA and other substmtes (DHA and LTB4). They will then define the effects of the metabolites formed on cerebral vascular tone and cerebral inflammation. Project 2 headed by Dr. Roman will explore the role of 20-HETE in the regulation of cerebral vascular tone following SAH in the rat. Project 3 will explore various aspects of a unique hypothesis for reactive hyperremia in the brain. Drs. Koehler and Gebremedhin will determine if glutamate released by neurons stimulates receptors on astrocytes to open novel Kc, channels and increase capacitive Ca 2+ entry in these cells. They propose that the elevation in Ca 2+ concentration stimulates the synthesis and/or release of EETs by astrocytes and dilates the adjacent cerebral vessels by opening Kca channels in these cells. Each of the projects will utilize the biochemical/molecular core for LC/MS measurements of EETs, 20-HETE and structural identification of other CYP metabolites of fatty acids. In addition, the work on all three projects will be supported through a consortium agreement with Dr. Falck of the University of Texas Southwestern Medical Center who will synthesize and provide inhibitors, agonists and antagonists. This program reflects a long-standing tradition of sharing technology and ideas between the program investigators and will greatly increase our understanding of the role of CYP fatty acids in the control of cerebral blood flow both in health and following SAH.