Mechanisms Underlying Carotid Body-dependent Sympathetic Activation by Chronic Intermittent Hypoxia

项目摘要-项目1 睡眠呼吸暂停（SA）是一种高度流行的呼吸系统疾病，仅在美国就影响数百万人。 慢性间歇性缺氧（CIH）是SA的标志性表现。SA患者和暴露于SA的啮齿动物 CIH表现出交感神经活性升高，这与引起自主神经共 病态项目1的总体目标是描绘CIH的周围神经机制， 诱导交感神经激活，并评估其对血压的影响。颈动脉体（CB）升高 化学反射被认为是CIH诱导的交感神经激活和气体放电的主要驱动力。 信使H2S通过CIH介导CB过度活跃。项目1旨在确定H2S如何导致CB 由CIH激活。我们检验了H2S作用于血管球细胞中嗅觉受体78（Olfr 78）的假设， 启动一个复杂的信号级联，涉及cAMP依赖性增加[Ca 2 +]I，导致CB CIH的多动症。我们结合生理学、生物化学和分子生物学的方法来测试这种可能性。 暴露于CIH的大鼠和小鼠以及表现出自发睡眠的小鼠的生物学方法 呼吸暂停和CB球细胞的原代培养物。AIM 1中的研究评估了Olfr 78在CB活化中的作用， CIH AIM 2确定CIH对CB的激活是否需要Olfr 78通过H2S对cAMP的激活。AIM 3 确定cAMP如何通过CIH导致CB激活。在AIM 4中进行实验，确定了CB的重要性 在表现出睡眠呼吸暂停的小鼠中CB兴奋和交感神经激活中的H2S-Olfr 78信号传导。主要 概念和技术创新包括：a）H2S通过气味受体介导CIH诱发的 CB兴奋对自主神经功能具有深远的影响，这在概念上是新颖的， 在本申请中提供的初步数据之外进行探索，B）评估发现的重要性 来自表现出自然睡眠呼吸暂停的小鼠中CIH的实验啮齿动物模型;和c）开发新的 技术来产生感兴趣的基因的CB特异性缺失。项目1的主题联系紧密， 项目2、3和4，并利用核心B设施：a）将大鼠和小鼠暴露于CIH，B）获得遗传 工程小鼠，c）基因的靶向缺失，和d）生物化学和分子生物学测定。成员 调查小组的成员在拟议办法方面具有长期经验和专门知识， 共同工作的记录，如联合出版物所证明。项目1的成功完成是 预计建立一个新的作用Olfr 78在介导的生物作用的H2S，这可能会导致 靶向H2S-Olfr 78信号传导以阻断CB反射依赖性交感神经的治疗策略 多动症。

Project Summary- Project 1 Sleep apnea (SA) is a highly prevalent respiratory disease affecting several million people in the USA alone. Chronic Intermittent Hypoxia (CIH) is a hallmark manifestation of SA. Patients with SA, and rodents exposed to CIH exhibit elevated sympathetic nerve activity, which has been implicated in causing autonomic co- morbidities. The overall goal of the Project 1 is to delineate peripheral neural mechanisms underlying CIH- induced sympathetic activation and assess its impact on blood pressure. A heightened carotid body (CB) chemo reflex has been implicated as a major driver of CIH-induced sympathetic activation and gaseous messenger H2S mediates CB hyperactivity by CIH. Project 1 seeks to determine how H2S causes the CB activation by CIH. We test the hypothesis that H2S acting on olfactory receptor 78 (Olfr78) in glomus cells initiates a complex signaling cascade, involving a cAMP-dependent increase in [Ca2+]I leading to CB hyperactivity by CIH. We test this possibility using a combination of physiological, biochemical and molecular biological approaches on rats and mice exposed to CIH as well as in mice exhibiting spontaneous sleep apnea, and primary cultures of CB glomus cells. Studies in AIM 1 assess the role of Olfr78 in CB activation by CIH. AIM 2 determines whether CB activation by CIH requires cAMP activation by Olfr78 by H2S. AIM 3 determines how cAMP leads to CB activation by CIH. Experiments in AIM 4, determines the importance of CB H2S-Olfr78 signaling in CB excitation and sympathetic activation in mice exhibiting sleep apnea. Major conceptual and technical innovations include: a) H2S acting through odorant receptors mediates CIH-evoked CB excitation with profound consequences on autonomic functions is conceptually novel and has not been explored beyond the preliminary data presented in this application, b) assessing the significance of findings from experimental rodent model of CIH in mice exhibiting natural sleep apnea; and c) development of novel techniques to generate CB specific deletion of genes of interest. Project 1 has tight thematic linkages to Projects 2, 3, and 4 and utilizes Core B facilities for: a) exposing rats and mice to CIH, b) obtaining genetically engineered mice, c) targeted deletion of genes, and d) biochemical and molecular biological assays. Members of the investigative team have long-standing experience and expertise with the proposed approaches and a track record of working together as evidenced by joint publications. Successful completion of Project 1 is anticipated to establish a novel role for Olfr78 in mediating biological actions of H2S, which might lead to therapeutic strategies targeting of H2S-Olfr78 signaling to block CB reflex-dependent sympathetic hyperactivity.