Peptidergic modulation of guinea pig intrinsic cardiac neurons

 描述（由申请人提供）：慢性心脏病诱导心脏组织和控制心脏的神经元系统内的功能和表型变化。自主神经元控制的不平衡导致副交感神经活动减少，加上交感神经活动增加和异质性增加，增加了心律失常和猝死的风险。心脏固有神经系统（ICN）是副交感神经自主控制心脏的最终共同通路，它整合了来自多个输入的信息，并可以在逐搏的基础上产生心脏功能的短环反射控制。虽然多项研究都集中在心脏应激诱导的交感神经元控制的变化，少得多的注意已经支付给外周副交感神经自主神经节内的信息处理的关键作用，以及它们如何重塑/适应施加的压力。这是我们的假设，心脏应激诱导的适应内在的心脏神经系统内的努力，以维持副交感神经传出输出通过功能和表型的改变，在选择内在的心脏神经元群体。ICN内的这些适应可以部分抵消与进行性心脏病相关的过度和异质交感神经兴奋的适应不良效应。 交感神经传出活动增加可通过交感神经传出纤维释放去甲肾上腺素和神经肽Y（NPY）增加，沿着交感神经诱导的肽激素血管紧张素II（AngII）及其代谢物Ang（1-7）的产生增加来改变心脏功能。为了明确肽水平改变对心脏病理学发展的重要性，本提案将评估豚鼠心肌梗死（MI）后心脏固有神经系统如何对AngII和NPY水平升高作出反应。使用豚鼠心脏神经丛的整体安装准备，我们将评估单个内在心脏神经元的生理反应，从控制和MI动物的组织中的血管紧张素II和神经肽Y。本研究的主要目的是：（1）确定血管紧张素Ⅱ受体（AT 1 R、AT 2 R、MasR）在心肌梗死后ICN输出调节中的作用;（2）确定心肌梗死后增加NPY释放对ICN的影响。我们将使用一个多学科的方法，其中包括从单个神经元在整个安装准备，完整的网络内的神经元，免疫组织化学和蛋白质和mRNA表达水平的生物化学测量的全细胞电压钳记录的尖锐电极电压记录。结合起来，这些研究的结果将有助于确定这些肽调节神经元功能的机制。这些信息可用于开发更好的药物治疗慢性心脏病。

 DESCRIPTION (provided by applicant): Chronic heart disease induces functional and phenotypic changes within cardiac tissues and the neuronal systems that control the heart. An imbalance in autonomic neuronal control that results in reduced parasympathetic activity coupled with increased and heterogeneous sympathetic activity increases the risk of cardiac arrhythmias and sudden death. The intrinsic cardiac nervous system (ICN), the final common pathway for parasympathetic autonomic control to the heart, integrates information from multiple inputs and can produce short-loop reflex control of cardiac function on a beat-to-beat basis. While multiple studies have focused on cardiac stress-induced changes in sympathetic neuronal control, much less attention has been paid to the critical role of information processing within peripheral parasympathetic autonomic ganglia and how they remodel/adapt to imposed stress. It is our hypothesis that cardiac stress-induced adaptations within the intrinsic cardiac nervous system represent efforts to maintain parasympathetic efferent output via functional and phenotypic alterations in select intrinsic cardiac neuronal populations. These adaptations within the ICN could counteract, in part, the maladaptive effects of excessive and heterogeneous sympathetic excitation associated with progressive cardiac disease. Increased sympathetic efferent activity can alter cardiac function through increased release of norepinephrine and neuropeptide Y (NPY) from sympathetic efferent fibers, along with sympathetic-induced increases in the production of the peptide hormone angiotensin II (AngII) and its metabolite, Ang(1-7). To specifically address the importance of altered peptide levels on the development of cardiac pathology, this proposal will evaluate how the intrinsic cardiac nervous system responds to elevated levels of AngII and NPY following myocardial infarction (MI) in the guinea pig. Using a whole mount preparation of the guinea pig cardiac plexus, we will evaluate the physiological responses of individual intrinsic cardiac neurons to AngII and NPY in tissues from control and MI animals. Our primary specific aims are (1) to determine the role of Angiotensin II receptors (AT1R, AT2R, MasR) in the modulation of ICN output with MI and (2) to determine the effects of increased release of NPY on the ICN following MI. We will use a multidisciplinary approach, which includes sharp electrode voltage recordings from individual neurons in the whole mount preparation, whole cell voltage clamp recordings from neurons within the intact network, immunohistochemistry, and biochemical measurements of protein and mRNA expression levels. Combined, the results from these studies will aid in determining the mechanisms by which these peptides can modulate neuronal function. This information can be used to develop better pharmacotherapies to treat chronic heart disease.