SYNAPTIC INTERACTIONS OF CARDIOINHIBITORY NEURONS

描述：（改编自摘要）中央副交感神经 控制心率、房室传导和心肌 收缩性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 疑核（NA）神经元内的髓质。 生理 有证据表明，四个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（SA）结， 房室结和心房或心室平滑肌， 调节SA自律性、AV传导、心房收缩性和 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 NA在解剖学上分离和功能选择性假说 神经元独立地控制SA率和AV传导。 数据表明 有一个纵向的负性心脏组织 尾侧NA的变时性和负向性神经元， 喙部NA，分别。 这个中枢神经系统组织反映了 组织的功能选择性心脏组成部分的 周围迷走神经 其他数据支持这一假设， 功能不同的NA心肌神经元群体是 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 旨在回答这样一个问题：“功能选择性是如何 和外周心脏抑制迷走神经运动神经元组织， 控制？“Dual labeling light and electron microscopic histochemical 并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的光学显微镜 神经解剖追踪方法，以进一步测试假设， 解剖学分离和功能选择性NA神经元 独立控制SA率和AV传导; 2）由光定义 在显微镜下观察NA神经元的心脏组织， 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， 突触相互作用的传入神经末梢含有 神经递质P物质、血清素、神经肽Y和脑啡肽 具有负变时性、负变频性和推定性 负性肌力NA神经元;和4）确定超微结构 心脏呼吸系统的选定部门之间的关系 孤束核（NTS）和负性变时性或 负向传导NA神经元。 这些信息将有助于定义 神经元回路介导的孤迷走神经成分的压力， 和化学感受器反射。 所提出的实验可以 有可能增强我们定义神经元回路的能力 心脏的副交感神经调节

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.