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：生物体响应全身血压突然升高而减少脑血流量的能力 （BP）被称为大脑自动调节（CAR）。与足月新生儿相比，早产儿无法减少 脑血流量（CBF）响应全身血压升高。对于早产儿，这会暴露脆弱的脑血管 高压下血流量显着增加，导致破裂和脑损伤。我们的初步研究 证明当全身血压升高时，近期胎儿可以收缩颈动脉并减少 CBF；然而，这 早产儿的能力尚未发育。我们还观察到，通过收缩颈动脉来减少 CBF 受肾上腺素能神经系统，特别是 α1 肾上腺素能受体 (α1-AR) 的活性调节。这些 早产儿颈动脉中受体的表达量明显较低。此外，我们观察到，以下 通过切断颈上神经节（SCG）来消除近期胎儿的肾上腺素能控制，使他们失去了 随着全身血压升高，减少流向大脑的颈动脉血流 (CaBF) 的能力。因此，去除 SCG 后，两者 早产儿和近足月胎儿在全身血压升高后不能降低 CBF。在离体实验中 在颈动脉段中，我们观察到 α1-AR 激动剂引起的早产动脉收缩明显低于 来自近期羔羊的那些。因此，我们得出结论，α1-ARs 活性的降低在调节中发挥着基础作用。 CaBF 随全身血压升高而变化。我们还观察到，早产儿中 α1-AR 激动剂的活性降低 与近足月胎儿羔羊相比，α1-AR 表达减少所致。此外，我们还提供证据 通过荧光素酶报告基因检测和组蛋白的参与，DNA 高甲基化降低了 α1-AR 启动子活性 修改。因此，我们将检验以下假设：启动子 DNA 高甲基化和组蛋白修饰会降低 α1-AR 亚型（α1A-、α1B-、α1D）在颈动脉中的表达和功能，并在成熟过程中发挥重要作用 从早产儿到足月胎儿的大脑自动调节。我们还将收集两性（男性与女性）的数据，以 识别与性别相关的变化。这些研究将在离体的颈动脉上进行，并在体内长期进行。 对胎羊进行导管插入。该假设将通过两个具体目标进行检验。目标 1：从早产儿到足月胎儿 具体方式，我们将对启动子DNA甲基化和组蛋白修饰进行深入的机制分析 颈动脉中α1-AR亚型的差异表达。目标 2：从早产儿到足月胎儿，以特定性别的方式， 我们将确定差异 α1-AR 亚型启动子甲基化、组蛋白修饰的功能意义， 以及基因表达对颈动脉收缩力和大脑血流调节的影响 系统压力。测量将在体内实时进行，每周胎儿在宫内成熟 从 105 天到 137 天。这将提供有关 α1-AR 亚型和表观遗传作用的有价值的信息。 CAR 成熟的机制。