SYNAPTIC INTERACTIONS OF CARDIOINHIBITORY NEURONS

描述：(改编自摘要)中枢副交感神经 心率、房室传导和心肌的控制 迷走神经内抑制性传出轴突的收缩作用 很有胆量。这些副交感神经节前轴突起源于 疑核(NA)神经元内的延髓。生理学 有证据表明，四个解剖分离的副交感神经 心脏神经节选择性投射到窦房结， 房室结，以及房室或室壁的平滑肌 调节窦房结自律性、房室传导、心房收缩能力和 左、右心室收缩能力。最近的解剖和 我们实验室的生理证据有力地支持了 解剖分离和功能选择性NA的假说 神经元独立控制窦性心动过速和房室传导。数据表明 有一种纵向的心脏专位组织阴性 中脑尾侧核和尾侧核内的变时性神经元和负变时性神经元 分别为吻侧NA。该CNS组织反映了 心脏功能选择性成分的组织 周围迷走神经。其他数据支持这样的假设 在功能上不同的NA心脏运动神经元是 利用不同的中枢神经传入神经末梢控制 神经递质或受体。因此，建议的实验是 旨在回答这样一个问题：“如何在功能上有选择性的中央 和外周心脏抑制迷走神经运动神经元组织和 受控？“双标记光镜和电子显微镜组织化学 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光学显微镜 神经解剖示踪方法进一步检验这一假说 解剖分离和功能选择性的NA神经元 独立控制SA率和房室传导；2)用光定义 显微镜下观察NA神经元的心脏定位组织 在功能上与房室控制有关 收缩性；3)通过双标记电子显微镜定义， 含突触的传入神经末梢的突触相互作用 神经递质P物质、5-羟色胺、神经肽Y和脑啡肽 有负的变时性、负变时性和推定 负性变力NA神经元；4)测定超微结构 部分心肺疾病患者的心肺分部之间的关系 孤束核(NTS)和负性变时性或 负向垂直性NA神经元。这些信息将有助于定义 调节孤束核-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 潜在地增强了我们定义神经元回路的能力 心脏的潜在副交感神经调节。

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.