SYNAPTIC INTERACTIONS OF CARDIOINHIBITORY NEURONS

心脏抑制神经元的突触相互作用

基本信息

批准号：
2445260
负责人：
Vito John Massari
金额：
$ 43.64万
依托单位：
HOWARD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1996
资助国家：
美国
起止时间：
1996-08-01 至 2000-06-30
项目状态：
已结题

项目摘要

DESCRIPTION: (adapted from the abstract) The central parasympathetic control of cardiac rate, atrio-ventricular conduction,and myocardial contractility is mediated by inhibitory efferent axons within the vagus nerve. These parasympathetic preganglionic axons originate in the medulla within neurons of the nucleus ambiguus(NA). Physiological evidence suggests that four anatomically segregated parasympathetic cardiac ganglia selectively project to the sinoatrial (SA) node, Atrioventricular(AV) node, and atrial or ventricular smooth muscle to regulate SA automaticity, AV conduction,atrial contractility and ventricular contractility, respectively. Recent anatomical and physiological evidence from our laboratory strongly support the hypothesis that anatomically separated and functionally selective NA neurons independently control SA rate and AV conduction. Data indicate that there is a longitudinal cardiotopic organization of negative chronotropic and negative dromotropic neurons in the caudal NA and rostral NA, respectively. This CNS organization mirrors the organization of functionally selective cardiac components of the peripheral vagus nerve. Other data support the hypothesis that functionally different populations of NA cardiomotor neurons are controlled by CNS afferent nerve terminals utilizing different neurotransmitters or receptors. The experiments proposed are therefore designed to answer the question, " How are functionally selective central and peripheral cardioinhibitory vagal motor neurons organized and controlled?" Dual labeling light- and electron microscopic histochemical and immunocytochemical techniques will be used. The investigators propose to 1) use two different independent light microscopic neuroanatomical tracing methods to further test the hypothesis that anatomically separated and functionally selective NA neurons independently control SA rate and AV conduction; 2) define by light microscopy the cardiotopic organization of NA neurons which are functionally associated with the control of atrial and ventricular contractility; 3) define by double labeling electron microscopy, the synaptic interactions of afferent nerve terminals containing the neurotransmitters substance P, serotonin, neuropeptide Y, and enkephalin with negative chronotropic, negative dromotropic and presumptive negative inotropic NA neurons; and 4) determine the ultrastructural relationships between selected cardiorespiratory divisions of the nucleus of the solitary tract (NTS) and negative chronotropic or negative dromotropic NA neurons. This information will help define the neuronal circuitry mediating the solitario-vagal components of the baro- and chemoreceptor reflexes. The experiments which are proposed can potentially enhance our ability to define the neuronal circuitry underlying parasympathetic regulation of the heart.

描述：（改编自摘要）中枢副交感神经控制心率、房室传导和心肌收缩力由迷走神经内的抑制性传出轴突介导神经。这些副交感神经节前轴突起源于髓质内有疑核（NA）神经元。生理有证据表明，四种解剖学上分离的副交感神经心脏神经节选择性地投射到窦房结（SA），房室 (AV) 结以及心房或心室平滑肌调节 SA 自动性、AV 传导、心房收缩力和分别为心室收缩力。最近的解剖学和我们实验室的生理学证据有力地支持了假设解剖学上分离且功能上选择性 NA 神经元独立控制 SA 速率和 AV 传导。数据表明存在负的纵向心脏组织尾部 NA 中的变时性和负向性神经元分别是嘴侧NA。这个 CNS 组织反映了功能选择性心脏成分的组织周围迷走神经。其他数据支持以下假设：功能不同的 NA 心肌运动神经元群是由 CNS 传入神经末梢控制，利用不同的神经递质或受体。因此，提出的实验是旨在回答这个问题：“功能选择性中心如何和外周心脏抑制性迷走神经运动神经元组织和受控？”双标记光镜和电镜组织化学将使用免疫细胞化学技术。调查人员建议1）使用两种不同的独立光镜神经解剖追踪方法进一步检验以下假设：解剖学上分离且具有功能选择性的 NA 神经元独立控制SA速率和AV传导； 2）通过光来定义显微镜下观察 NA 神经元的心脏组织在功能上与心房和心室的控制相关收缩性； 3) 通过双标记电子显微镜定义，传入神经末梢的突触相互作用包含神经递质 P 物质、血清素、神经肽 Y 和脑啡肽具有负变时性、负变时性和推定性负性肌力 NA 神经元； 4) 确定超微结构选定的心肺科之间的关系孤束核（NTS）和负变时性或负向促性 NA 神经元。此信息将有助于定义介导压力的孤立迷走神经成分的神经元回路和化学感受器反射。所提出的实验可以潜在地增强我们定义神经元回路的能力心脏的潜在副交感神经调节。