Role Of Neuropeptides And Biogenic Amines In Stress And

神经肽和生物胺在压力和压力中的作用

• 批准号: 6824171
• 负责人: JUAN M SAAVEDRA
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6824171
• 关键词: angiotensin II; angiotensin receptor; angiotensins; brain circulation; brain mapping; cerebral ischemia /hypoxia; gene expression; hormone receptor; hormone regulation /control mechanism; human tissue; laboratory mouse; neural plasticity; neuropeptide receptor; neuropeptides; polymerase chain reaction; receptor expression; stress

Our laboratory is focused on the study of the central functions of the hormone and brain modulator Angiotensin II, and in particular on its role in the regulation of the cerebral circulation and the reaction to stress. We have earlier discovered that pre-treating spontaneously (genetic) hypertensive rats (SHR) with an inhibitor of the peripheral, cerebrovascular and brain Angiotensin II AT1 receptors, candesartan, protected against subsequent brain ischemia resulting from occlusion of a major cerebral artery, reversed the hypertension-induced shifts in cerebral blood flow autoregulation, preserves blood flow above a critical threshold at the periphery of the ischemic zone, reversed the pathological cerebrovascular remodeling characteristic of hypertension, and thus normalized cerebrovascular compliance. We recently found that inhibition of the Angiotensin II system by AT1 receptor blockade antagonized Angiotensin II-induced cerebrovascular growth and inflammation. The AT1 receptor blocker, when administered peripherally, decreased iNOS, increased eNOS and decreased ICAM-1 in cerebrovascular beds, eliminated macrophage infiltration and reduced inflammation in cerebral arteries. AT1 receptor antagonists appear superior, in its therapeutic potential for brain ischemia and stroke, when compared to other anti-hypertension medications. We then initiated a series of experiments to clarify the mechanisms of such protection and reduction of ischemia. We constructed a large database, with the use of Gene Chip Expression Analysis, of changes in gene expression in microvessels of hypertensive and normotensive rats, treated with the AT1 receptor antagonist or vehicle. We are in the preliminary stages of data analysis, and we found that the AT1 receptor blockade increases the expression of the AT2 receptor, an Angiotensin II receptor type that may counteract the growth-promoting and inflammatory effects of AT1 receptor stimulation. In addition, a large number of heat shock protein genes are regulated in microvessels from hypertensive rats, and in turn are regulated by AT1 receptor antagonism. Thus, important mechanisms are emerging, to partially explain the protective effect of AT1 receptor antagonism. AT1 receptors regulate eNOS and iNOS, restoring the equilibrium between these two isoenzymes; AT1 receptor inhibition promotes expression of the AT2 receptor, and heat shock proteins play important roles in the process of protection from ischemia. A role of AT1 receptor inhibition in the protection from brain ischemia, beyond its effects in blood pressure control, begins to emerge. Our studies continue with the analysis of specific groups of genes selected on the basis of carefully researched specific questions, and the results obtained with the Microarrays are carefully controlled and confirmed by means of RT-PCR for gene expression, Western blot for protein expression and immunohistochemistry, to localize the regulated proteins to specific cell types. While AT1 receptor antagonists can be proposed to be elective first class antihypertensive medications with additional properties to protect from brain ischemia, the role of AT2 receptors as a target for treatment of ischemic conditions of the brain begins to be clarified. Our recent finding that peripheral administration of the AT2 antagonist PD 123319 inhibits brain AT2 receptors will allow us to advance in our understanding of the role of central AT2 receptors. We have earlier found that in addition to its vasoconstrictive, pro-hypertensive, pro-ischemic properties, Angiotensin II is an important stress hormone, and that pretreatment with a peripheral and central AT1 receptor antagonist completely prevents the sympathoadrenal response to isolation stress, including a modulation of TH transcription through regulation of transcription factors and including an interaction with AT2 receptors. We asked the question whether AT1 receptor antagonism could prevent a stress-induced illness, and we found that blockade of AT1 receptors completely prevented the production of stress-induced gastric ulcers in the rat during cold-restraint. We then found that multiple mechanisms were responsible for this effect, including protection of local gastric blood flow, selective inhibition of the sympathetic response to stress, and anti-inflammatory effects including decrease in ICAM expression and neutrophil infiltration in the gastric mucosa. The anti-inflammatory effects of AT1 receptor antagonism were of great interest, and coincided with the anti-inflammatory effects earlier described in the brain vasculature. We have recently extended these studies to determine if the AT1 receptor antagonists could reverse gastric ulcers produced not by stress but by administration of anti-inflammatory compounds such as indomethacin. We found that AT1 receptor antagonists can effectively prevent indomethacin-induced ulcers, predominantly through their anti-inflammatory effects, including modulation of heat shock protein, leptin and ICAM expression. Prevention of gastric ulcer formation, predominantly through anti-inflammatory effects, is a new finding of potentially important clinical implications. Our experiments continue to clarify our initial findings that in rodents, AT1 receptor blockade has an anxiolytic effect, as determined by behavioral studies using the Plus Maze. We propose that the anxiolytic effects are related to the modulation of AT1 receptor antagonists of brain CRH and GABAA receptor expression. This may indicate that AT1 receptor antagonists may be considered as a possible novel class of anti-anxiety medications. Because these compounds are devoid of addictive properties, development of new compounds of this class may result in anti-anxiety medications of great therapeutic potential. In addition, we have completed a two-and-a half year study to determine if life-long administration of the AT1 receptor antagonist affected rodent life span and if so, to determine the mechanisms of this effect. We chose Spontaneously Hypertensive Rats, and compared them with normotensive controls. We found a very significant extension of the life span of hypertensive animals, in parallel with cardiac and renal protection. We are in the process to determine if such end organ protection extends to the brain, and to clarify the mechanisms. In conclusion, our studies indicate that non-peptidic antagonists of the AT1 receptor with central effects may be considered among the drugs of choice in the treatment of cardiovascular disease and brain ischemia, protect against stress-related disorders, exert important peripheral and central anti-inflammatory effects, and may be useful compounds to develop effective and non-addictive anti-anxiety and anti-stress drugs. We are planning to propose the first clinical study to determine if such compounds could be effectively used in the clinic to treat anxiety and stress-related disorders, and we continue our efforts to further clarify their mechanisms of action. The study of the complementary effects of AT2 receptor agonism and antagonism is another important direction in our current search for new and effective compounds of psychiatric interest.

我们的实验室专注于研究激素和大脑调节剂血管紧张素II的中心功能，特别是其在调节大脑循环和应激反应中的作用。 我们之前发现，用外周、脑血管和大脑血管紧张素 II AT1 受体抑制剂坎地沙坦预先治疗自发性（遗传性）高血压大鼠（SHR），可防止随后因主要大脑动脉闭塞而导致的脑缺血，逆转高血压引起的脑血流自动调节变化，保留血流 高于缺血区外围的临界阈值，逆转了高血压的病理性脑血管重塑特征，从而使脑血管顺应性正常化。我们最近发现，通过 AT1 受体阻断来抑制血管紧张素 II 系统可以拮抗血管紧张素 II 诱导的脑血管生长和炎症。 AT1受体阻滞剂在外周给药时，可减少脑血管床中的iNOS、增加eNOS并减少ICAM-1，消除巨噬细胞浸润并减少脑动脉炎症。与其他抗高血压药物相比，AT1 受体拮抗剂在治疗脑缺血和中风方面的潜力似乎更胜一筹。然后我们启动了一系列实验来阐明这种保护和减少缺血的机制。我们利用基因芯片表达分析构建了一个大型数据库，记录了接受 AT1 受体拮抗剂或媒介物治疗的高血压和正常血压大鼠微血管中基因表达的变化。我们正处于数据分析的初步阶段，我们发现 AT1 受体阻断会增加 AT2 受体的表达，AT2 受体是一种血管紧张素 II 受体类型，可能抵消 AT1 受体刺激的生长促进和炎症作用。此外，高血压大鼠的微血管中大量热休克蛋白基因受到调节，进而受到AT1受体拮抗作用的调节。因此，重要的机制正在出现，以部分解释 AT1 受体拮抗作用的保护作用。 AT1受体调节eNOS和iNOS，恢复这两种同工酶之间的平衡； AT1受体抑制促进AT2受体表达，热休克蛋白在缺血保护过程中发挥重要作用。除了控制血压之外，AT1 受体抑制在防止脑缺血方面的作用也开始显现。我们的研究继续对根据仔细研究的具体问题选择的特定基因组进行分析，并通过基因表达的 RT-PCR、蛋白质表达的蛋白质印迹和免疫组织化学仔细控制和确认使用微阵列获得的结果，以将调节的蛋白质定位到特定的细胞类型。虽然 AT1 受体拮抗剂可以被提议作为选择性的一流抗高血压药物，具有防止脑缺血的附加特性，但 AT2 受体作为治疗脑缺血性疾病的靶点的作用开始得到澄清。我们最近发现外周给药 AT2 拮抗剂 PD 123319 会抑制大脑 AT2 受体，这将使我们进一步了解中枢 AT2 受体的作用。 我们之前发现，血管紧张素 II 除了具有血管收缩、促高血压、促缺血的特性外，还是一种重要的应激激素，用外周和中枢 AT1 受体拮抗剂进行预处理可以完全阻止交感肾上腺对隔离应激的反应，包括通过转录因子的调节来调节 TH 转录，以及与 AT2 受体的相互作用。我们提出了 AT1 受体拮抗剂是否可以预防应激诱发的疾病的问题，我们发现 AT1 受体的阻断完全阻止了大鼠在寒冷限制期间应激诱发的胃溃疡的产生。然后我们发现多种机制导致了这种效应，包括保护局部胃血流、选择性抑制交感神经对应激的反应以及抗炎作用，包括减少胃粘膜中 ICAM 表达和中性粒细胞浸润。 AT1 受体拮抗作用的抗炎作用引起了人们的极大兴趣，并且与之前描述的脑血管系统中的抗炎作用相一致。我们最近扩展了这些研究，以确定 AT1 受体拮抗剂是否可以逆转不是由压力而是由消炎痛等抗炎化合物引起的胃溃疡。我们发现 AT1 受体拮抗剂可以有效预防吲哚美辛诱发的溃疡，主要是通过其抗炎作用，包括调节热休克蛋白、瘦素和 ICAM 表达。主要通过抗炎作用预防胃溃疡形成，是具有潜在重要临床意义的新发现。 我们的实验继续阐明我们的初步发现，即在啮齿类动物中，AT1 受体阻断具有抗焦虑作用，正如使用 Plus Maze 的行为研究所确定的那样。我们认为抗焦虑作用与 AT1 受体拮抗剂对大脑 CRH 和 GABAA 受体表达的调节有关。这可能表明 AT1 受体拮抗剂可能被视为一类可能的新型抗焦虑药物。由于这些化合物没有成瘾性，因此开发此类新化合物可能会产生具有巨大治疗潜力的抗焦虑药物。 此外，我们还完成了一项为期两年半的研究，以确定终生施用 AT1 受体拮抗剂是否会影响啮齿动物的寿命，如果会影响，则确定这种影响的机制。我们选择自发性高血压大鼠，并将其与正常血压对照进行比较。我们发现高血压动物的寿命显着延长，同时心脏和肾脏得到保护。我们正在确定这种终末器官保护是否延伸到大脑，并阐明其机制。 总之，我们的研究表明，具有中枢作用的 AT1 受体非肽拮抗剂可被视为治疗心血管疾病和脑缺血的首选药物，可预防应激相关疾病，发挥重要的外周和中枢抗炎作用，并且可能是开发有效且非成瘾的抗焦虑和抗应激药物的有用化合物。我们计划提出第一项临床研究，以确定此类化合物是否可以有效地用于临床治疗焦虑和压力相关疾病，并且我们将继续努力进一步阐明其作用机制。 AT2受体激动和拮抗作用的互补作用的研究是我们当前寻找新的、有效的精神病学化合物的另一个重要方向。