Receptor Targeting and Plasticity in NTS

孤立束核（NTS）是与化学反射诱导的血压升高和高血压引起的压力感受器反射重置最相关的大脑区域，这两种情况都可以通过局部血管紧张素-1 （AT1）受体的激活来调节。项目2将测试中心假设，即NTS中的AT1受体具有亚细胞分布，支持直接参与cherno和/或压力感觉反射以及与儿茶酚胺和NAD(P)H氧化酶的相互作用，NAD(P)H氧化酶与血管紧张素II的急性和长期效应有关（Angll）。这将通过(1)相关受体和NAD(P)H氧化酶亚基的高分辨率电镜免疫细胞化学双重标记，以及(2)通过大鼠NTS中DiA的顺行转运鉴定的压力感觉神经元的超微结构分析和膜片钳记录来实现。有5个具体目标。目的1和2将验证AT1和α 2-肾上腺素能受体共同定位于突触前轴突或其在NTS中的树突靶点的假设，其中它们的分布与它们的激动剂对化学或压力感觉神经元的相反作用一致。目的3将验证Ang II在NTS压力感觉神经元中的生理作用是通过打开电压依赖性ca2 +通道介导的，ca2 +通道也受到NAD(P)H氧化酶产生的活性氧（ROS）的影响，其亚基存在于许多含有AT1受体的细胞中。电压门控ca2 +通道的打开对于NMDA和某些类型的AMPA受体的激活是必不可少的，它们分别是化学感觉和压力感觉传递的主要介质。这些受体，如NAD(P)H氧化酶，由多个亚基组成，表现出对血浆和细胞质膜的活性依赖动员。谷氨酸（Aim 4）或NAD(P)H氧化酶（Aim 5）亚基免疫金标记亚细胞分布的变化将用于研究这种可塑性在睡眠呼吸暂停大鼠模型中慢性间歇性缺氧或angl诱导高血压引起的血压升高中的潜在作用。总之，这些结果将有助于理解大脑机制的发展和维持

The nucleus of the solitary tract (NTS) is the brain region most implicated in chemoreflex-induced blood pressure elevation and hypertension-evoked resetting of baroreceptor reflexes, both of which can be modulated through activation of local angiotensin-1 (AT1) receptors. Project 2 will test the central hypothesis that AT1 receptors in the NTS have subcellular distributions supporting direct involvement in cherno- and/or barosensory reflexes and interactions with both catecholamines and NAD(P)H oxidase, an enzyme implicated in the acute and long-term effects of angiotensin II (Angll). This will be achieved by using (1) high resolution electron microscopic immunocytochemical dual labeling of the relevant receptors and NAD(P)H oxidase subunits, and (2) both ultrastructural analysis and patch-clamp recording in barosensory neurons identified by anterograde transport of DiA in rat NTS. There are 5 Specific Aims. Aims 1 and 2 will test the hypothesis that AT1 and alpha2-adrenergic receptors are co-localized within presynaptic axons or their dendritic targets in the NTS, where their distributions are consistent with opposing actions of their agonists on chemo- or barosensory neurons. Aim 3 will test the hypothesis that the physiological actions of Ang II in NTS barosensory neurons are mediated through opening of voltage-dependent Ca 2+ channels also affected by reactive oxygen species (ROS) generated by NAD(P)H oxidase, whose subunits are present in many of the cells that contain AT1 receptors. The opening of voltage-gated Ca 2+ channels is essential for activation of NMDA and certain types of AMPA receptors that are the major mediators of chemosensory and barosensory transmission, respectively. These receptors, like NAD(P)H oxidase, are composed of multiple subunits showing activity-dependent mobilization to plasma and cytoplasmic membranes. Changes in the subcellular distribution of immunogold labeling for glutamate (Aim 4) or NAD(P)H oxidase (Aim 5) subunits will be used to study the potential role of this plasticity in the blood pressure elevations produced either by chronic intermittent hypoxia in the rat model of sleep apnea, or Angll-induced hypertension. Together, the results will contribute to understanding the brain mechanisms underlying the development and maintenance of hypertension.