Oxidant Stress in the Brain and Hypertension

描述（由申请人提供）：原发性高血压（HTN）是一个主要的健康问题，困扰着30%的人口，易患影响大脑、心脏和肾脏的严重疾病。有令人信服的证据表明，本质HTN的特点是神经体液功能障碍，和不适当的血管紧张素II（AngII）信号在中枢神经系统（CNS）是一个主要的罪魁祸首。穹窿下器官（SFO）是一种前脑结构，缺乏血脑屏障，被认为是循环因子进入CNS的关键“门户”，与AngII依赖性HTN密切相关。在该资助的前几个周期中，我们已经证明了SFO中AngII（1型受体，AT 1 R）诱导的活性氧（ROS）信号传导介导了“慢升压”AngII HTN，这是一种慢性小鼠模型，重现了必需HTN的关键特征。然而，我们对SFO中AngII诱导的ROS形成如何转化为对控制血压的神经通路的强大影响的理解仍然不完全。最近，内质网（ER）应激已成为许多心血管和代谢疾病中的主要氧化还原相关机制;然而，其在HTN中的作用尚不清楚。AngII现在与几种心血管细胞类型中的ER应激直接相关，并且CNS中的ER应激通过已知参与脑AngII依赖性HTN的分子机制导致神经功能的长期变化。在过去的一年中，我们已经获得了令人兴奋的初步数据，显示在培养的神经元和在体内的SFO中AngII，ROS和ER应激之间的联系，沿着的证据表明，在中枢神经系统中的ER应激的化学操作对血压有显着的影响。基于这些发现，我们建议测试的总体假设，ER应力在SFO提供了一个重要的联系之间的AngII，ROS和中枢神经系统的改变，导致HTN的AngII慢升压小鼠模型。目的1将利用分子、免疫细胞化学和超微结构分析来验证AngII在体内诱导SFO中AT 1 R依赖性ER应激的假设。目的2将验证这一假设，即ER应激和氧化应激的耦合是SFO中AngII介导的慢升压效应的关键。这将通过病毒递送ROS清除剂、遗传ER应激抑制剂和用于SFO原位ROS测量的氧化荧光探针的组合来实现。目的3将利用SFO靶向的ER能力的遗传操作结合综合心血管生理学来检验SFO中的ER应激是慢升压AngII HTN和相关神经体液后遗症的因果因素的假设。该项目的一个显著优势是研究人员在中枢神经心血管调节和HTN（Davisson，Mark）、ER应激生物学（考夫曼，Qi）、氧化还原生物学（Davisson，考夫曼）和CNS CV回路的神经解剖学（Pickel，Pierce）方面具有互补的专业知识。该项目解决了HTN研究中一个非常新颖的课题，有可能从根本上促进对CNS与HTN联系的基本机制的理解，这可能为新的治疗方法提供线索。该项目也有可能在HTN研究中开辟新的道路。 公共卫生相关性：高血压是一个主要的全球性健康问题，困扰着近三分之一的普通人群。它对大脑、心脏和肾脏有毁灭性的影响。该项目解决了高血压研究中一种高度新颖的致病机制，有可能从根本上推进我们对大脑与心血管疾病联系的基本机制的理解。这可能为针对高血压及其许多并发症的神经源性成分的新治疗方法提供重要线索。

DESCRIPTION (provided by applicant): Essential hypertension (HTN) is a major health problem, afflicting 30% of the population and predisposing to serious diseases affecting the brain, heart and kidneys. There is compelling evidence that essential HTN is characterized by neurohumoral dysfunction, and inappropriate angiotensin II (AngII) signaling in the central nervous system (CNS) is a primary culprit. The subfornical organ (SFO), a forebrain structure that lacks a blood-brain-barrier and is considered a key "gateway" to the CNS for circulating factors, is strongly implicated in AngII-dependent HTN. In previous cycles of this grant, we have shown that AngII (type 1 receptor, AT1R)- induced reactive oxygen species (ROS) signaling in the SFO mediates "slow-pressor" AngII HTN, a chronic mouse model that recapitulates key features of essential HTN. However, our understanding of how AngII- induced ROS formation in the SFO translates into powerful effects on neural pathways controlling blood pressure is still incomplete. Recently, endoplasmic reticulum (ER) stress has emerged as a major redox- associated mechanism in a number of cardiovascular and metabolic diseases; its role in HTN, however, is not known. AngII is now directly linked to ER stress in several cardiovascular cell types, and ER stress in the CNS leads to long-term changes in neural function through molecular mechanisms known to be involved in brain AngII-dependent HTN. During the past year, we have obtained exciting preliminary data showing links between AngII, ROS and ER stress in cultured neurons and in the SFO in vivo, along with evidence that chemical manipulation of ER stress in the CNS has significant effects on blood pressure. Based on these findings, we propose to test the overall hypothesis that ER stress in the SFO provides an important link between AngII, ROS and CNS alterations that lead to HTN in the AngII slow-pressor mouse model. Aim 1 will utilize molecular, immunocytochemical and ultrastructural analyses to test the hypothesis that AngII induces AT1R- dependent ER stress in the SFO in vivo. Aim 2 will test the hypothesis that the coupling of ER stress and oxidant stress is critical in slow-pressor AngII-mediated effects in the SFO. This will be accomplished through a combination of viral delivery of ROS scavengers, a genetic ER stress inhibitor and oxidative fluoroprobes for ROS measurements in the SFO in situ. Aim 3 will utilize SFO-targeted genetic manipulations of ER capacity combined with integrative cardiovascular physiology to test the hypothesis that ER stress in the SFO is a causal factor in slow-pressor AngII HTN and related neurohumoral sequelae. A notable strength of the project is the involvement of investigators with complementary expertise in central neural cardiovascular regulation and HTN (Davisson, Mark), ER stress biology (Kaufman, Qi), redox biology (Davisson, Kaufman) and neuroanatomy of CNS CV circuits (Pickel, Pierce). This project, which addresses a highly novel topic in HTN research, has the potential to fundamentally advance understanding of basic mechanisms linking the CNS with HTN, which could provide clues into novel treatments. The project also has the potential to forge new trails in HTN research. PUBLIC HEALTH RELEVANCE: Hypertension is a major global health problem, afflicting nearly a third of the general population. It has devastating effects on the brain, heart and kidneys. This project, which addresses a highly novel pathogenic mechanism in hypertension research, has the potential to fundamentally advance our understanding of basic mechanisms that link the brain with cardiovascular disease. This could provide important clues to novel therapeutic approaches targeting the neurogenic component of hypertension and its many complications.