Autonomic and Antihypertensive Actions of Neuronal CGRP/RAMP1 Receptors

神经元 CGRP/RAMP1 受体的自主神经和抗高血压作用

• 批准号: 8330367
• 负责人: MARK W CHAPLEAU
• 金额: --
• 依托单位: IOWA CITY VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8330367
• 关键词: Adenoviruses; Afferent Neurons; Aging; Angiotensin II; Angiotensin II Receptor; Animals; Antihypertensive Agents; Antioxidants; Anxiety; Arrhythmia; Arteries; Attenuated; Baroreflex; Binding; Blood Pressure; Blood Vessels; Brain; Brain Stem; Brain region; Buffers; Calcitonin Gene-Related Peptide; Calcitonin-Gene Related Peptide Receptor; Cardiovascular system; Cell Nucleus; Conscious; Data; Development; Diabetes Mellitus; Dysautonomias; Electric Stimulation; Electrocardiogram; Employee Strikes; Endothelium; Exhibits; Female; Gene Expression; General Population; Healthcare Systems; Heart Rate; Heart failure; Hormones; Human; Hypertension; Implant; Incidence; Infusion procedures; Injection of therapeutic agent; Knockout Mice; Measurement; Measures; Mediating; Migraine; Motor Activity; Mus; Muscle; Myocardial Infarction; NADPH Oxidase; Nerve; Nervous system structure; Neural Pathways; Neuraxis; Neurogenic Inflammation; Neuromodulator; Neurons; Nociception; Oxidative Stress; Patients; Peripheral; Phenotype; Phenylephrine; Pressoreceptors; Process; Proteins; Protocols documentation; RAMP1; Reactive Oxygen Species; Reflex action; Regulation; Reporting; Research; Resistance; Role; Sensory; Sensory Ganglia; Sensory Nerve Endings; Site; Source; Stroke; Subfornical Organ; Telemetry; Testing; Tissues; Transgenic Mice; Vascular Diseases; Vasodilation; Vasodilator Agents; Veterans; Viral Vector; afferent nerve; autocrine; blood pressure regulation; cell type; cost; heart rate variability; improved; indexing; male; nestin protein; neuromechanism; neuroregulation; novel; osmotic minipump; overexpression; paracrine; paraventricular nucleus; prevent; promoter; receptor; receptor expression; receptor-activity-modifying protein; recombinase; relating to nervous system; release factor; research study; response; telemetering; tempol; therapeutic target; therapy design; trafficking

DESCRIPTION (provided by applicant): Calcitonin gene-related peptide (CGRP) functions as an autocrine/paracrine factor, hormone and neuro- modulator. While best known for its potent vasodilator activity, CGRP is involved in many neural processes including nociception, neurogenic inflammation, migraine and anxiety. The CGRP receptor has an obligatory requirement for a subunit called Receptor Activity-Modifying Protein 1 (RAMP1). RAMP1 enhances CGRP binding to the receptor and receptor trafficking. While the role of vascular CGRP receptors is well recognized, the role of nervous system CGRP receptors in blood pressure regulation remains unclear. T he proposed studies will test the hypothesis that nervous system CGRP/RAMP1 receptors are powerful modulators of baroreflex sensitivity and autonomic activity capable of preventing or reversing hypertension. The specific aims of the proposed research are to: (1) Determine whether selective overexpression of RAMP1 in the nervous system improves autonomic regulation and attenuates angiotensin II (Ang-II) and phenylephrine-induced hypertension, and conversely if deletion of nervous system RAMP1 impairs auto- nomic regulation and enhances hypertension; (2) Identify nervous system sites of CGRP/RAMP1 receptor expression responsible for autonomic and blood pressure phenotypes in the nervous system-targeted RAMP1 transgenic and knockout mice; and (3) Test the hypothesis that activation of nervous system CGRP/ RAMP1 receptors abrogates Ang-II induced dysautonomia and hypertension by reducing oxidative stress. Our preliminary data indicate that just a 1.5-fold overexpression of RAMP1 in the nervous system improves autonomic regulation and nearly abolishes Ang-II hypertension. We will measure autonomic and cardiovascular phenotypes in male and female RAMP1 transgenic and knockout mice using the nervous system-specific nestin Cre-recombinase to globally target the nervous system and local injections of viral vectors expressing Cre-recombinase to target specific brain regions including brainstem, subfornical organ and paraventricular nucleus. Blood pressure, heart rate, locomotor activity and an array of autonomic indices will be measured in conscious mice implanted with blood pressure and ECG telemeters, both under basal conditions and during hypertension induced by 4-week infusions of Ang-II and phenylephrine delivered by osmotic minipump. To separate effects on sensory vs. central com- ponents of the baroreflex, complementary experiments will be performed in anesthetized mice that include measurements of baroreceptor afferent nerve activity from aortic depressor nerve and reflex changes in heart rate and blood pressure during graded electrical stimulation of baroreceptor afferents. Systemic and central infusions of the antioxidant tempol and central injections of viral vectors encoding siRNAs targeted to NADPH oxidase subunits will be used to determine the role of oxidative stress in mediating autonomic dysregulation and hypertension. Gene expression of CGRP, CGRP receptor subunits, Ang-II receptors, and pro- and anti- oxidant molecules will be measured in the relevant brain regions, sensory ganglia, and peripheral arteries. The significance of identifying nervous system CGRP/RAMP1 receptors as positive modulators of autonomic control relates to their potential as therapeutic targets for treatment of dysautonomia in hyperten- sion, and other pathological states such as heart failure and diabetes. Inhibition of Ang II-mediated effects by activation of CGRP/RAMP1 receptors has widespread implications in hypertension and heart failure.

描述(由申请人提供)： 降钙素基因相关肽(CGRP)是一种自分泌/旁分泌因子、激素和神经调节剂。虽然CGRP以其强大的血管扩张活性而闻名，但它参与了许多神经过程，包括伤害性感受、神经源性炎症、偏头痛和焦虑。降钙素基因相关肽受体对受体活性修饰蛋白1(RAMP1)有一个必需的亚单位。RAMP1增强CGRP与受体的结合和受体的运输。虽然血管CGRP受体的作用已被公认，但神经系统CGRP受体在血压调节中的作用仍不清楚。提出的研究将验证神经系统CGRP/RAMP1受体是压力反射敏感性和自主神经活动的强大调节器，能够预防或逆转高血压的假设。拟议研究的具体目的是：(1)确定RAMP1在神经系统中的选择性过表达是否能改善自主神经调节并减轻血管紧张素II(Ang-II)和苯肾上腺素诱导的高血压，反之，神经系统RAMP1的缺失是否会损害自我调节并增强高血压；(2)确定在神经系统靶向RAMP1转基因和基因敲除小鼠中，CGRP/RAMP1受体表达与自主神经和血压表型有关的神经系统位点；以及(3)检验神经系统CGRP/RAMP1受体激活通过减少氧化应激而抑制Ang-II诱导的自主神经紊乱和高血压的假设。我们的初步数据表明，仅1.5倍的RAMP1在神经系统中的过度表达就可以改善自主神经调节，并几乎消除Ang-II高血压。我们将测量雄性和雌性RAMP1转基因和敲除小鼠的自主神经和心血管表型，使用神经系统特异的巢蛋白Cre-重组酶来全局靶向神经系统，并局部注射表达Cre-重组酶的病毒载体来靶向特定的大脑区域，包括脑干、穹隆下器和室旁核。在植入血压和心电遥测仪的清醒小鼠中，将测量血压、心率、运动活动和一系列自主神经指数，无论是在基础条件下，还是在通过渗透性微泵注射Ang-II和苯肾上腺素4周诱导的高血压期间。为了分离压力感受器反射对感觉成分和中枢成分的影响，将在麻醉小鼠上进行补充实验，包括测量主动脉降压神经的压力感受器传入神经活动，以及在分级电刺激压力感受器传入时心率和血压的反射变化。全身和中枢注射抗氧化剂Temol，以及中心注射编码针对NADPH氧化酶亚基的siRNA的病毒载体，将用于确定氧化应激在介导自主神经失调和高血压中的作用。将在相关的大脑区域、感觉神经节和外周动脉中检测CGRP、CGRP受体亚单位、Ang-II受体以及前和抗氧化分子的基因表达。确定神经系统CGRP/RAMP1受体为自主神经控制的正向调节剂的意义与它们作为治疗高血压以及其他病理状态如心力衰竭和糖尿病的自主神经障碍的潜在靶点有关。通过激活CGRP/RAMP1受体抑制Ang II介导的效应在高血压和心力衰竭中具有广泛的意义。