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: 6507482
• 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/6507482
• 关键词: angiotensin II; angiotensin receptor; angiotensins; brain circulation; brain mapping; cerebral ischemia /hypoxia; hormone receptor; hormone regulation /control mechanism; human tissue; laboratory mouse; neural plasticity; neuropeptide receptor; receptor expression; stress

Our laboratory is focused on the study of the central functions of the hormone and brain modulator Angiotensin II (Ang II), and in particular on its role in the regulation of the cerebral circulation and the reaction to stress. In hypertension, excess AT1 receptor stimulation promotes cerebrovascular growth and vasoconstriction, with decreased arterial compliance and susceptibility to ischemia. We found that in spontaneously (genetic) hypertensive rats (SHR), AT1 antagonism with a non-peptidic, selective, potent and insurmountable antagonist of the physiologically active Ang II AT1 receptors, candesartan, remodels brain arteries, increasing their compliance and their resistance to ischemia. When male untreated SHR, submitted to experimental stroke by occlusion of the middle cerebral artery, are pretreated with AT1 receptor antagonists for two to four weeks before ischemia, the blood flow is preserved above a critical threshold in the periphery of the ischemic zone, with a very significant reduction of the cortical volume of ischemia and in a decrease in brain edema. The effects of AT1 antagonists are more pronounced than those of inhibitors of Ang II formation (ACE inhibitors) and far superior than those of calcium channel or adrenergic receptor blockers. We also demonstrated an important role of brain AT1 receptors by intracerebral administration of an AT1 receptor antisense oligonucleotide, which protects against cerebral ischemia. We conclude that AT1 receptor inhibitors may be the treatment of choice for patients with increased risk of cerebral ischemia, and that blockade of brain AT1 receptors decreases neuronal death during ischemia. Ang II is an important stress hormone. We found that pretreatment with a peripheral and central AT1 receptor antagonist completely prevents the sympathoadrenal response to isolation stress, decreasing the formation of the catecholamine rate-limiting enzyme, tyrosine hydroxylase (TH), the adrenal catecholamine content, and the adrenal catecholamine release during stress. The molecular mechanism involves a reduction of the stress-induced increase in Fra-2, a protein that interacts with the AP-1 binding site in the TH promoter region, probably through AT1/AT2 receptor cross talk, because inhibition of AT2 receptors reduces basal Fra-2 levels. In addition, AT1 and AT2 receptors are colocalized in adrenomedullary neurons, and they mutually regulate their expression. In AT2 receptor gene-deficient model, absence of AT2 receptor expression results in increased AT1 receptors in the paraventricular nucleus, and this correlates with activation of their pituitary-adrenal axis. This explains the increased sensitivity to stress in this mice model. Pretreatment with AT1 receptor blockers also prevents the hypothalamic-pituitary hormonal response to isolation stress, and reverses the decrease in CRH mRNA in rat paraventricular nucleus produced by isolation stress. This indicates that inhibition of CRH formation is an important component of the central protective action of AT1 antagonists. Inhibition of AT1 receptors completely prevents the stress-induced decrease in CRH1 receptors in rat frontal, parietal and cingulate cortex and the stress-induced increase in CRH2beta receptors in the choroids plexus, suggesting that Ang II AT1 receptors modulate multiple CRH systems. Finally, AT1 receptor inhibition prevents the development of stress-induced gastric ulcers and exerts anxiolytic effects in the rat. Our observations strongly indicate that inhibition of AT1 receptors has therapeutic potential in stress-related disorders. In AT2 receptor gene-deficient mice, selective populations of AT1 receptors are upregulated, not only in the adrenal gland and brain but also in other organs such the kidney, spleen and lung, but not in the liver. Many of the cells expressing higher AT1 receptor number do not express AT2 receptors, raising the possibility of extracellular and/or intercellular cross-talk mechanisms for AT1/AT2 receptors. Increased kidney AT1 receptors in AT2 receptor gene-deficient mice partially explain the phenotype in this model, higher blood pressure and increased response to exogenously administered Ang II. These findings also raise the possibility of a protective function of AT2 receptors in the kidney. In the inner medulla of the kidney of female mice, AT2 receptors are highly expressed, and their expression is strongly estrogen-dependent. This may explain gender differences in renal vasodilation and function. If AT2 receptors are regulated by estrogen in other organs, and in particular in the brain, this could explain some of the protective effect of estrogens in cerebral ischemia. Non-peptidic antagonists of the AT1 receptor are among the drugs of choice in the treatment of cardiovascular disease. We have shown that, in addition, these compounds may exert therapeutic benefits in the protection against brain ischemia and stress-related disorders. For this reason, an in-depth analysis of the molecular requirements of the binding site for non-peptidic antagonists of the AT1 receptor was important. We took advantage of two naturally occurring mutations, in the two gerbil AT1 receptor subtypes, gAT1A and gAT1B, cloned in our laboratory. The gAT1A receptor has an affinity for non-peptidic antagonists about 400-fold lower than that of the hAT1 receptor, while the affinity for these compounds in the gAT1B receptor is about 40-fold lower when compared to the hAT1 receptor. Gerbil receptors have very few non-conserved amino acids when compared to AT1 receptors from other mammalian species, including human. With the use of gain-of-function and loss-of-function mutations in the gAT1A, gAT1B and hAT1 receptors, we found that positions 107, 108, and 195 are crucial for determination of affinity of the AT1 receptor to non-peptidic antagonists of therapeutic efficacy. These observations may be of importance for the design of new, more potent and selective non-peptidic AT1 antagonists of therapeutic efficacy.

我们的实验室专注于研究激素和脑调节剂血管紧张素II（ANG II）的中心功能，尤其是其在调节大脑循环的作用以及对应激的反应。 在高血压中，过量的AT1受体刺激会促进脑血管生长和血管收缩，并降低动脉依从性和对缺血的敏感性。我们发现，在生理上活性的ANG II AT1受体，Candesartan，Remodels Brain Alteries，增强其依从性及其对局部性的抵抗力的生理活性ANG II AT1受体AT1受体AT1受体AT1受体AT1受体AT1受体II AT 1受体II AT ANG II AT1受体II AT ANG AT AT 1拮抗作用（SHR）（SHR）（SHR）（SHR），AT1拮抗作用。当雄性未经治疗的SHR通过阻塞中部大脑动脉塞入实验中风时，在缺血前的AT1受体拮抗剂预处理两到四个星期，在缺血区域的外围阈值以上，血液流动在缺血区域的关键阈值以上，并非常明显地减少了Ischemia和ischemia的皮质减少。 AT1拮抗剂的作用比Ang II形成（ACE抑制剂）的抑制剂的作用更为明显，并且比钙通道或肾上腺素能受体阻滞剂的作用要高得多。我们还通过脑内施用AT1受体反义寡核苷酸来证明大脑AT1受体的重要作用，该寡核苷酸可预防脑缺血。我们得出的结论是，对于患有脑缺血风险增加的患者，AT1受体抑制剂可能是选择的治疗方法，而大脑AT1受体的阻断会减少缺血期间的神经元死亡。 ANG II是重要的应激激素。我们发现，用外周种和中央AT1受体拮抗剂进行预处理，完全防止了对隔离胁迫的交感神经反应，从而减少了伴有儿茶酚胺速率限制酶的形成，酪氨酸羟化酶（TH），肾上腺素肾上腺素含量，肾上腺肾上腺素含量和肾上腺肾上腺释放的压力。分子机制涉及减少应力诱导的FRA-2的增加，FRA-2（一种与TH启动子区域中AP-1结合位点相互作用的蛋白质，可能是通过AT1/AT2受体交叉讲座，因为抑制AT2受体会降低基底FRA-FA-2水平。此外，AT1和AT2受体在肾上腺肾上腺神经元中共定位，它们相互调节其表达。在AT2受体基因缺陷模型中，缺乏AT2受体表达会导致旁腔核中AT1受体增加，这与它们的垂体 - 肾上腺轴的激活相关。这解释了该小鼠模型中对压力的敏感性提高。 用AT1受体阻滞剂进行预处理还可以防止下丘脑 - 垂体激素对分离应激的反应，并逆转通过分离应激产生的大鼠旁腔室中CRH mRNA的降低。这表明抑制CRH形成是AT1拮抗剂中心保护作用的重要组成部分。对AT1受体的抑制完全防止了大鼠额叶，顶和扣带回皮质的CRH1受体的降低，以及脉络膜丛中CRH2BETA受体的应力诱导的增加，表明ANG II AT1受体调节了多个CRH系统。最后，AT1受体抑制可防止应激诱导的胃溃疡的发展，并在大鼠中发挥抗焦虑作用。我们的观察结果强烈表明，对AT1受体的抑制具有与压力相关疾病的治疗潜力。 在AT2受体基因缺陷型小鼠中，AT1受体的选择性种群不仅在肾上腺和大脑中，而且在其他器官中，例如肾脏，脾脏和肺部，而且在肝脏中。许多表达较高AT1受体数的细胞不表达AT2受体，从而提高了AT1/AT2受体的细胞外和/或细胞间交叉机理的可能性。在AT2受体基因缺陷型小鼠中增加的肾脏ATNNEY AT1受体部分解释了该模型中的表型，更高的血压以及对外源给予的ANG II的反应增加。这些发现还提高了肾脏中AT2受体保护功能的可能性。在雌性小鼠肾脏的内髓中，AT2受体高度表达，它们的表达非常依赖于雌激素。这可以解释肾血管舒张和功能方面的性别差异。如果AT2受体在其他器官中，尤其是在大脑中受到雌激素的调节，这可以解释雌激素在脑缺血中的某些保护作用。 AT1受体的非肽拮抗剂是治疗心血管疾病的首选药物之一。我们已经表明，此外，这些化合物可能在保护脑缺血和与压力有关的疾病的保护方面具有治疗益处。因此，对AT1受体非肽拮抗剂的结合位点的分子需求进行了深入的分析非常重要。我们利用了两个天然发生的突变，即在我们的实验室中克隆的两个Gerbil AT1受体亚型GAT1A和GAT1B。 GAT1A受体对非肽拮抗剂的亲和力比HAT1受体低约400倍，而与HAT1受体相比，GAT1B受体中对这些化合物的亲和力低约40倍。与其他哺乳动物物种（包括人）的AT1受体相比，沙鼠受体的非保守氨基酸很少。在使用GAT1A，GAT1B和HAT1受体中使用功能丧失和功能丧失突变，我们发现位置107、108和195对于确定AT1受体与治疗疗效的非肽拮抗剂的亲和力至关重要。这些观察结果对于设计新的，更有效和选择性的非肽AT1治疗功效的拮抗剂的设计可能至关重要。