The effect of AT1R antisense on centrally-mediated responses to angiotension II

描述(由申请人提供)：高血压影响了大约5000万美国人，这种疾病的发展显著增加了心脏和肾功能衰竭的风险。高血压的发展被认为部分是由于肾素-血管紧张素系统(RAS)的过度活动，RAS是一个对心血管功能和水矿物质平衡调节至关重要的内分泌系统。血管紧张素II(AngII)是RAS的效应肽，它介导对失血、钠耗竭和低血压的代偿反应。在外周，Angii通过与血管上的血管紧张素1型受体(AT1R)结合，引起血管收缩并促进Na+重吸收。在大脑中，AngII与脑室周围器官(CVO)中的AT1R结合，启动激素释放、交感神经流出以及增加水和钠的消耗的变化。虽然血管紧张素转换酶对血管系统反应性和肾脏钠离子转运的影响已为人所知，但调控血管紧张素转换酶反应的中枢通路仍不清楚。以前的研究使用AT1R拮抗剂或脑损伤来检查中枢对血管紧张素转换酶的反应，但这些方法有局限性。损伤研究允许评估大脑区域的功能，但缺乏提供特定神经元表型信息的分辨率。相反，药物操作可以评估神经元的表型，但将药物的给药限制在离散的大脑区域是有问题的。另一种方法是使用反义方法在离散的大脑区域抑制靶基因的表达。给药反义改变了个别脑区的特定神经元表型，从而可以评估这个离散人群中神经元的功能。在拟议的实验中，将使用反义寡核苷酸来抑制AT1R在特定脑核的表达，从而评估这些受体在调节循环血管紧张素Ⅱ反应中的作用。具体地说，针对AT1R的反义基因将被注射到大鼠特定的CVO中。随后，我将检查行为、内分泌和神经反应对不同地增加循环血管紧张素Ⅱ的治疗。这些结果将为AT1R在特定脑区的功能以及它们在调节对循环血管紧张素Ⅱ的反应中所起的作用提供有价值的见解，同时也为未来采用中枢遗传操作的研究奠定基础。

DESCRIPTION (provided by applicant): Hypertension affects approximately 50 million Americans and progression of this disease significantly increases risks for heart and renal failure. The development of hypertension is believed to be due, in part, to overactivity of the Renin-Angiotensin-System (RAS), an endocrine system critical for the regulation of cardiovascular function and hydromineral balance. The effector peptide of the RAS, angiotensin II (ANGII), mediates compensatory responses to blood loss, sodium depletion, and hypotension. In the periphery, ANGII elicits vasoconstriction and promotes Na+ reabsorption by binding to angiotensin type 1 receptors (AT1R) on blood vessels. In the brain, ANGII binds to AT1R in circumventricular organs (CVOs) to initiate changes in hormone release, sympathetic outflow, and increased water and sodium consumption. While much is known about the effects of ANGII on vasculature reactivity and renal Na+ handling, the central pathways governing responses to ANGII remain unclear. Previous studies have used AT1R antagonists or brain lesions to examine central responses to ANGII, but these approaches have limitations. Lesion studies allow for the evaluation of the function of brain regions, but lack the resolution to provide information about specific neuronal phenotypes. Conversely, pharmacological manipulations allow evaluation of neuronal phenotypes, but limiting the administration of the drug to discrete brain regions is problematic. An alternative method is to use antisense methodology to inhibit the expression of target genes in discrete brain regions. Administration of antisense alters specific neuronal phenotypes within individual brain regions, thereby allowing evaluation of the function of neurons within this discrete population. For the proposed experiments, antisense will be used to inhibit the expression of the AT1R in specific brain nuclei, thereby allowing evaluation of the role of these receptors in mediating responses to circulating ANGII. Specifically, antisense targeted against the AT1R will be injected into specific CVOs of rats. Subsequently, I will examine behavioral, endocrine, and neural responses to treatments that differentially increase circulating ANGII. The results will provide valuable insight to the function of AT1R within specific brain regions and the role they play in mediating responses to circulating ANGII, while also serving as a foundation for future studies employing central genetic manipulations.