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：机体在应对全身血压突然升高时减少脑血流量的能力 (BP)被称为脑自动调节(CAR)。与足月儿相比，早产儿不能减少 脑血流量(CBF)对全身血压升高的反应。对于早产儿，这暴露了脆弱的脑血管 在高压下血流量显著增加，导致血管破裂和脑损伤。我们的初步研究 证明当全身血压升高时，近月胎儿可以收缩颈动脉并减少脑血流量；然而，这一点 早产儿的能力并不发达。我们还观察到颈动脉收缩以减少CBF是 受肾上腺素能神经系统的调节，特别是受α-1肾上腺素能受体(α1-ARs)活性的调节。这些 受体在早产儿颈动脉中的表达明显较少。此外，我们还观察到，在 切断颈上神经节(SCG)使近足月胎儿失去肾上腺素能控制 随着全身血压的升高，减少流入大脑的颈动脉血流量(CaBF)的能力。因此，在撤除政务司司长后，两者 在全身血压升高后，早产儿和近月儿不能降低脑血流量。在体外实验中 颈动脉节段，我们观察到α1-Ars激动剂对早产动脉收缩的反应显著低于 那些来自短期羊肉的。因此，我们得出结论，α1-ARs活性降低在调控中起着基础性作用 CaBF与全身性BP升高。我们还观察到早产儿α1-Ars激动剂活性的降低 与近足月胎羊相比，α-1-ARs的表达减少。此外，我们提出了证据 荧光素酶报告基因高甲基化降低α1-Ars启动子活性及组蛋白参与 修改。因此，我们将检验这样一个假设，即启动子DNA超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及其在颈动脉成熟中的作用 从早产到足月胎儿的大脑自我调节。我们还将收集两性(男性与女性)的数据，以 确定与性有关的变化。这些研究将在分离的颈动脉上进行体外研究，并在体内长期进行 留置尿管的胎羊。这一假设将通过两个具体目标进行检验。目标1：从早产到足月胎儿的性别-- 具体来说，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α-1-AR亚型差异表达的研究目标2：从早产胎儿到足月胎儿，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、 和基因表达对颈动脉收缩能力和脑血流调节的反应 全身压力。测量将在活体内实时进行，每周进行一次宫内胎儿成熟 从105天增加到137天。这将提供关于α1-AR亚型的作用和表观遗传学的有价值的信息 CAR成熟所涉及的机制。