The role of Alpha1-Adrenergic Receptors Promoter Methylation in Cerebral Autoregulation in Fetus

α1-肾上腺素能受体启动子甲基化在胎儿大脑自动调节中的作用

• 批准号: 10657080
• 负责人: Ravi Goyal
• 金额: $ 38.38万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-07 至 2028-02-29
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10657080
• 关键词: Acetylation; Adrenergic Agents; Adrenergic Agonists; Adrenergic Receptor; Animals; Basic Science; Biological Assay; Birth; Blood Pressure; Blood flow; Brain; Brain Injuries; Carotid Arteries; Catecholamines; Catheterization; Cerebrovascular Circulation; Cerebrum; Chronic; DNA; DNA Methylation; Data; Disabled Persons; Epigenetic Process; Excision; Face; Family; Female; Fetal Sheep; Fetus; Gene Expression; Gestational Age; Histone Acetylation; Homeostasis; Hormones; Human; Hypermethylation; Impairment; Incidence; Infant; Knowledge; Laser-Doppler Flowmetry; Learning Disabilities; Life; Low Birth Weight Infant; Luciferases; Measurement; Measures; Methylation; Nervous System; Neurologic; Newborn Infant; Organism; Outcome; Pathway interactions; Phenylephrine; Play; Premature Birth; Premature Infant; Regulation; Reporter; Research; Role; Rupture; Series; Sheep; Side; Stress; Structure of superior cervical ganglion; System; Systemic blood pressure; Testing; Therapeutic; Time; alpha-1 adrenergic receptors; blood pressure elevation; cerebral capillary; cognitive disability; constriction; differential expression; disability; experimental study; fetal; histone modification; in utero; in vivo; insight; life-long learning; male; neonate; pressure; preterm newborn; prevent; promoter; receptor; response; sex; transmission process

Summary: The ability of an organism to reduce the brain blood flow in response to sudden surges in systemic blood pressure (BP) is known as cerebral autoregulation (CAR). In contrast to term neonates, preterm neonates are not able to reduce cerebral blood flow (CBF) in response to increased systemic BP. In preterm neonates, this exposes fragile cerebral vessels to a significantly increased blood flow at high pressure, leading to their rupture and brain damage. Our preliminary studies demonstrate that near-term fetuses can constrict carotid arteries and reduce CBF when systemic BP rises; however, this capability is not developed in the preterm fetus. We also observed that the constriction of carotid arteries to reduce CBF is regulated by the adrenergic nervous system, specifically by the activities of alpha-1 adrenergic receptors (α1-ARs). These receptors are expressed at a significantly lower number in preterm carotid arteries. Also, we observed that following the removal of adrenergic control in the near-term fetus by severing the superior cervical ganglion (SCG) made them lose their ability to reduce carotid blood flow (CaBF) to the brain with the rise in systemic BP. Thus, after the removal of SCG, both preterm and near-term fetuses cannot reduce CBF following an increase in systemic BP. During ex-vivo experiments on carotid segments, we observed that preterm arterial constriction in response to α1-ARs agonist was significantly lower than those from near-term lambs. Thus, we concluded that reduced activities of α1-ARs play a fundamental role in regulating CaBF with the rise in systemic BP. We also observed that the reduction in the activities of α1-ARs agonists in preterm resulted from reduced expression of α1-ARs compared to those in near-term fetal lambs. Furthermore, we present evidence that DNA hypermethylation reduces α1-ARs promoter activities by luciferase reporter assays and the involvement of histone modifications. Thus, we will test the hypothesis that promoter DNA hypermethylation and histone modifications reduce the expression and function of α1-AR subtypes (α1A-, α1B-, α1D) in the carotid arteries and play an essential role in the maturation of cerebral autoregulation from preterm to term fetus. We will also collect data from both sexes (male versus female) to identify sex-related changes. The studies will be conducted ex-vivo on isolated carotid arteries and in vivo in chronically catheterized fetal sheep. The hypothesis will be tested with two specific aims. Aim 1: From preterm to term fetus in a sex- specific manner, we will conduct an in-depth mechanistic analysis of promoter DNA methylation and histone modifications on differential expression of α1-AR subtypes in carotid arteries. Aim 2: From preterm to term fetus, in a sex-specific manner, we will determine the functional significance of differential α1-AR subtypes promoter methylation, histone modifications, and gene expression on carotid artery contractility and blood flow regulation to the brain in response to an increase in systemic pressure. The measurements will be conducted in real-time, in-vivo, with in-utero fetal maturation every week from 105 to 137 days. This will provide valuable information regarding the role of α1-AR subtypes and the epigenetic mechanisms involved in the maturation of CAR.

摘要：有机体能够减少脑血流而响应全身血压的突然激增的能力 （BP）被称为脑自动调节（CAR）。与术语新生儿相比，早产新生儿无法减少 响应于全身性BP的响应脑血流（CBF）。在早产新生儿中，这暴露了脆弱的脑血管 高压下的血液流量显着增加，导致其破裂和脑损伤。我们的初步研究 证明近期胎儿可以收缩颈动脉，并在全身性BP上升时减少CBF；但是，这个 早产胎儿没有发展能力。我们还观察到，颈动脉减少CBF的收缩是 受肾上腺神经系统的调节，特别是由α-1肾上腺素受体（α1-ARS）的活性调节。这些 在早产颈动脉中，受体以显着较低的数量表达。另外，我们观察到遵循 通过几个上宫颈神经节（SCG）使近期胎儿的肾上腺控制控制使他们失去了 随着全身性BP的增加，能够减少颈动脉血流（CABF）到大脑。在删除SCG之后，两者都 全身性BP增加后，早产和近期胎儿无法减少CBF。在实体实验期间 颈动脉片段，我们观察到，对α1-ARS激动剂的反应早产动脉收缩显着低于 那些来自近期羔羊。我们得出的结论是，减少的α1-AR的活动在调节中起着基本作用 CABF随着全身性BP的增加。我们还观察到早产中α1-ARS激动剂的活性的减少 与近期胎儿羔羊相比，α1-AR的表达降低。此外，我们提供证据 DNA高甲基化可通过荧光素酶报告基准测定和组蛋白参与来降低α1ARS启动子的活性 修改。这是我们将检验的假设，即启动子DNA高甲基化和Hisstone修饰降低了 颈动脉中α1-AR亚型（α1a-，α1b-，α1d）的表达和功能，在成熟中起着至关重要的作用 从早产到胎儿的脑自动调节。我们还将收集来自男女的数据（男性与女性） 确定与性别相关的变化。研究将在分离的颈动脉和体内进行长期进行的研究 导管胎羊。该假设将以两个具体目标进行检验。目标1：从早产到性别的胎儿 - 特定方式，我们将对启动子DNA甲基化和Hisstone修饰进行深入的机械分析 关于颈动脉中α1-ar亚型的差异表达。目标2：从早产到胎儿，以性别特定的方式， 我们将确定差异α1-ar亚型甲基化，Hisstone修饰的功能显着性， 以及对颈动脉收缩力和血流调节向大脑的基因表达，以响应增加 系统性压力。测量结果将在体内实时进行，每周胎儿成熟 从105到137天。这将提供有关α1-ar亚型和表观遗传的作用的宝贵信息 汽车成熟涉及的机制。