Role of the PVN in Chronic Intermittent Hypoxia-Induced Cardiorespiratory Changes

描述（由申请人提供）： 阻塞性睡眠呼吸暂停、夜间哮喘和心血管疾病与反复缺氧发作或慢性间歇性缺氧（CIH）相关，这反过来又导致与呼吸驱动的长期易化（LTF）和交感神经流出增加相关的缺氧后变化。CIH的效应通过颈动脉体和孤束核（NTS）的二级神经元传递到脑干呼吸和心血管调节部位。然而，含有加压素和/或催产素的下丘脑室旁（PVN）神经元也接受来自NTS的输入。这些神经元的一个亚群项目的延髓（RVLM）和中线5-羟色胺（S-HT）产生的神经元，在调节膈神经和舌下神经放电和球脊髓交感神经元的活性的重要作用的网站的吻腹外侧区。我的项目是基于中央的假设，CIH，通过下调GABA能抑制性输入的PVN，将导致过度兴奋的加压素和/或催产素的PVN神经元，通过中线的多巴胺能和RVLM神经元增强舌下神经和膈运动神经元和交感神经兴奋性节前神经元的反应，以一个新的缺氧暴露。研究将分两个阶段进行。在辅导阶段，我将发展与研究计划相关的实验技能，并描述CIH对PVN GABA能抑制性输入的影响（目标1：研究1-3）。在独立阶段I中，将确定PVN在CIH诱导的中线含5-HT细胞的LTF中的作用，其影响膈神经和舌下神经的活性（目的1：研究4和目的2）。此外，我将研究加压素和/或催产素信号通路在CIH诱导的交感神经活性上调中的作用（目的3）。将在对照组和实验组大鼠停止最后一次暴露于7天或4周CIH后24小时进行研究。我将使用免疫组织化学、分子方法（真实的时间PCR、蛋白质印迹分析、HPLC和受体配体结合分析）和生理实验（神经传递阻断和神经记录）来确定GABA能抑制性输入到PVN中含有加压素和催产素的神经元在CIH诱导的呼吸和心血管变化中的作用。这些研究将有助于更好地了解CIH诱导的心肺变化所涉及的神经机制，并有助于设计特定的治疗方案，治疗与反复缺氧相关的疾病。这个奖项的获得将使我在追求我的职业目标研究PVN在调解压力相关的自主神经紊乱的作用独立。

DESCRIPTION (provided by applicant): Obstructive sleep apnea, nocturnal asthma, and cardiovascular disorders are associated with repeated hypoxic episodes or chronic intermittent hypoxia (CIH), that in turn, cause post-hypoxic changes associated with long-term facilitation (LTF) of respiratory drive and increased sympathetic outflow. The effects of CIH are transmitted through carotid bodies and second order neurons of the nucleus tractus solitarius (NTS), to brainstem respiratory and cardiovascular regulating sites. However, hypothalamic paraventricular (PVN) neurons containing vasopressin and/or oxytocin, also receive inputs from the NTS. A subpopulation of these neurons projects to the rostral ventrolateral region of the medulla oblongata (RVLM) and midline serotonin (S-HT)-producing neurons, sites that play an important role in regulation of phrenic and hypoglossal nerve discharge and activity of bulbospinal sympathoexcitatory neurons. My project is based on the central hypothesis that CIH, via downregulation of GABAergic inhibitory inputs to the PVN, will lead to overexcitation of vasopressin- and/or oxytocin-containing PVN neurons that through midline serotonergic and RVLM glutamatergic neurons enhance the responses of hypoglossal and phrenic motoneurons and of sympathoexcitatory preganglionic neurons to a new hypoxic exposure. Studies will be carried out in two phases. In the mentored phase I will develop my experimental skills pertinent to the research plan and characterize effects of CIH on GABAergic inhibitory inputs to the PVN (Aim 1: Studies 1-3). In the independent phase I will determine the role of the PVN in CIH induced LTF of midline 5-HT-containing cells affecting activity of phrenic and hpoglossal nerves (Aim 1: Study 4 and Aim 2). In addition, I will investigate the role of vasopressin and/or oxytocin signaling pathways in CIH-induced upregulation of sympathetic activity (Aim 3). Studies will be performed in control and experimental rats at 24 hours after cessation of their last exposure to seven days or four weeks of CIH. I will define the role of GABAergic inhibitory inputs to PVN vasopressin- and oxytocin-containing neurons in CIH-induced respiratory and cardiovascular changes, using immunohistochemistry, molecular approaches (real time PCR, Western blot analysis, HPLC and receptor-ligand Binding assay), and physiological experiments (blockade of neural transmission and nerve recording). These studies will contribute to better understanding of neuronal mechanisms involved in CIH-induced cardiorespiratory changes, and aid in designing specific therapeutic regimes in treatment of conditions associated with repeated oxygen deprivation. The attainment of this award will make me independent in pursuing my career goal study the role of the PVN in mediating stress-related autonomic disturbances.