Altered CNS Intercellular Signaling Mechanisms in Cardiovascular Disease

描述（由申请人提供）：神经体液激活，包括交感神经兴奋和循环激素水平升高，如加压素，是心力衰竭（HF）病理生理学的主要参与者，直接影响该疾病的发病率和死亡率。虽然下丘脑室旁核（PVN）和视上核（SON）对心衰神经体液激活的贡献已经确定，但对心衰中这些核内神经元活性增加的精确细胞机制的全面理解仍然难以捉摸。神经元细胞内Ca2+水平（D[Ca2+]I）的活动依赖性变化不仅是影响膜兴奋性的关键信号，而且还影响神经可塑性和基因表达。兴奋性递质谷氨酸主要通过NMDA受体（NMDAR）发挥作用，是D[Ca2+]I信号（NMDA- dca2 +）的主要来源，在神经分泌和前交感神经元活动的调节中发挥重要作用。重要的是，越来越多的证据支持心衰患者谷氨酸功能加重。此外，与NMDA-DCa2+直接相关的其他信号机制（如一氧化氮、ROS、GABA）也在HF中发生改变。NMDA-DCa2+的整体功能后果在很大程度上取决于D[Ca2+]I的时空模式，因此，阐明影响NMDA-DCa2+特性的确切机制，以及这些机制的异常变化如何导致HF中神经元活动加剧，是高度相关的。我们已经获得了令人兴奋的初步数据，支持线粒体，传统上被视为静态细胞发电厂，是积极影响的关键和动态细胞器

DESCRIPTION (provided by applicant): Neurohumoral activation, including sympathoexcitation and increased circulating hormonal levels such as vasopressin, is a major player in the pathophysiology of heart failure (HF), directly influencing morbidity and mortality i this disease. While the contribution of the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei to neurohumoral activation in HF is established, a comprehensive understanding of the precise cellular mechanisms contributing to increased neuronal activity within these nuclei in HF remains elusive. Activity-dependent changes in neuronal intracellular Ca2+ levels (D[Ca2+]I)act as a critical signal influencing not only membrane excitability, but also neuroplasticity and gene expression. The excitatory transmitter glutamate, acting primarily via NMDA receptors (NMDAR), is a major source of D[Ca2+]I signaling (NMDA-DCa2+], playing an important role in the regulation of neurosecretory and presympathetic neuronal activity. Importantly, a growing body of evidence supports an exacerbated glutamate function in HF. Moreover, other signaling mechanisms that are directly linked to NMDA-DCa2+ (e.g, nitric oxide, ROS, GABA) are also altered in HF. The overall functional consequences of NMDA-DCa2+ are largely dependent on the spatiotemporal pattern of the D[Ca2+]I Thus, elucidating the precise mechanisms that influence the NMDA-DCa2+ properties, and how abnormal changes in these mechanisms may contribute to exacerbated neuronal activity in HF, is highly relevant. We have obtained exciting preliminary data supporting that mitochondria, classically viewed as static cellular power plants, are critical and dynamic organelles that actively influence NMDAR efficacy, by restraining its Ca2+-dependent coupling to other intracellular signaling pathways, influencing in turn overall SON/PVN neurosecretory and presympathetic neuronal activity. Moreover, we found that a blunted NMDAR- mitochondria crosstalk results in an enhanced NMDAR efficacy and exacerbated NMDA-DCa2+ leading to increased activation of the Ca2+- dependent family of TRP channels, and ultimately, abnormally elevated neuronal activity in HF. Here, we will test the central hypothesis that disruption of mitochondrial structurl-functional integrity results in exacerbated glutamate excitatory function, which via a strengthened coupling to Ca2+-sensitive TRPM4 channels, leads to enhanced neuronal activity in HF. This hypothesis will be tested in 3 specific aims: 1- To elucidate the role of mitochondria in shaping NMDAR-[Ca2+]i signaling in SON/PVN neurons, 2- To elucidate structural and functional mitochondrial mechanisms contributing to altered NMDAR-[Ca2+]i signaling in SON/PVN neurons HF rats, and 3- To determine the consequences of mitochondrial dysfunction on NMDAR-mediated neuronal excitability in HF rats. We expect results from this work to broaden our understanding of basic cellular mechanisms contributing to the hypothalamic regulation of neurohumoral outflows, and how changes in these mechanisms may contribute to neurohumoral activation in heart failure.