Effects of obstructive sleep apnea on cerebral circulation

阻塞性睡眠呼吸暂停对脑循环的影响

• 批准号: 8796240
• 负责人: ROBERT M BRYAN
• 金额: $ 34.23万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8796240
• 关键词: Adult; Affect; Aging; Arteries; Attenuated; Biological Availability; Breathing; Cardiovascular Diseases; Cerebrovascular Circulation; Cerebrovascular Disorders; Cerebrum; Dementia; Elderly; Endothelin; Endothelin Receptor; Endothelin-1; Endothelium; Event; Functional disorder; Generations; Goals; Homeostasis; Human; Hypercapnia; Incidence; Laser-Doppler Flowmetry; Measurement; Mediating; Modeling; Obesity; Obstructive Sleep Apnea; Oxidative Stress; Pathway interactions; Phenotype; Population; Rattus; Reactive Oxygen Species; Regulation; Risk; Risk Factors; Severities; Site; Sleep; Smooth Muscle; Stroke; System; Techniques; Testing; United States; Vascular Smooth Muscle; Vibrissae; arteriole; cerebral artery; cerebral atrophy; cerebrovascular; effective therapy; in vivo; novel; response; soft tissue

DESCRIPTION (provided by applicant): Obstructive sleep apnea (OSA) is defined by interrupted breathing during sleep due to a collapse of the soft tissues in the upper airway. It affects up to 25% of the adult population and is often overlooked as being an underlying cause for a number of pathological conditions. Although OSA has strong associations to cerebrovascular diseases including stroke and dementia, mechanisms that underlie the effects of OSA on endothelium and smooth muscle, the sites for cerebral blood flow (CBF) control, are unknown. The purpose of this proposal is to initiate studies required for understanding the pathological mechanisms associated with cerebrovascular dysfunction following OSA. One unique aspect of these studies involves our rat model of OSA. In this newly developed model, we will obstruct the airway during the sleep cycle in unanesthetized, freely- ranging rats. This model has several important features that more closely mimics OSA as it occurs in the human and will help to provide a more complete understanding of the pathological events associated with OSA in the cerebral circulation. We propose that ROS and endothelin act in a pathological cycle to produce a hypercontractile phenotype in cerebral arteries and arterioles. That is, during OSA, generation of ROS upregulates the endothelin pathway and the endothelin pathway generates ROS. Further, we propose that breaking this pathological cycle by either scavenging ROS or inhibiting the endothelin pathway will inhibit the pathological alterations in cerebral vessels. We will test the following hypothesis: During OSA a cycle between ROS generation and endothelin produces pathological alterations in the cerebrovascular wall and disrupts cerebral blood flow. We will test our hypothesis in three specific aims. (SA1) Determine if breaking the cycle between ROS and ET-1 by reducing ROS will alleviate the cerebrovascular dysfunction in arteries and arterioles in rats following 28 days of OSA. (SA2) Determine if breaking the cycle between ROS and ET-1 by blocking endothelin receptors will alleviate the cerebrovascular dysfunction in arteries and arterioles in rats following 28 days of OSA. (SA3) Determine if 28 days of OSA decreases CBF, attenuates the CBF response to whisker stimulation, attenuates autoregulation, or attenuates the CBF response to hypercapnia. Determine if reducing ROS and/or blocking endothelin receptors restores these responses in vivo. We will complete these specific aims using isolated pressurized cerebral arteries and arterioles and measurement of CBF with autoradiographic techniques and laser Doppler flowmetry. Completion of these studies will move us toward a better understanding of the underlying mechanisms of cerebrovascular dysfunction and towards more effective treatments to reduce the devastating effects of OSA on the cerebral circulation with a goal of reducing the incidence of stroke and the severity of dementias.

描述（由申请人提供）：阻塞性睡眠呼吸暂停（OSA）是指由于上呼吸道软组织塌陷而导致睡眠期间呼吸中断。它影响着高达 25% 的成年人口，并且经常被忽视为许多病理状况的根本原因。尽管 OSA 与中风和痴呆等脑血管疾病密切相关，但 OSA 对内皮和平滑肌（脑血流 (CBF) 控制部位）影响的机制尚不清楚。该提案的目的是启动了解 OSA 后脑血管功能障碍相关病理机制所需的研究。这些研究的一个独特之处涉及我们的 OSA 大鼠模型。在这个新开发的模型中，我们将在未麻醉、自由活动的大鼠的睡眠周期中阻塞气道。该模型具有几个重要特征，可以更接近地模拟人类发生的 OSA，并将有助于更全面地了解与脑循环中 OSA 相关的病理事件。我们认为，ROS 和内皮素在病理循环中发挥作用，在脑动脉和小动脉中产生过度收缩表型。也就是说，在OSA期间，ROS的产生上调内皮素途径并且内皮素途径产生ROS。此外，我们建议通过清除ROS或抑制内皮素途径来打破这种病理循环将抑制脑血管的病理改变。我们将检验以下假设：在 OSA 期间，ROS 生成和内皮素之间的循环会导致脑血管壁发生病理改变并扰乱脑血流。我们将在三个具体目标上检验我们的假设。 (SA1) 确定通过减少 ROS 来打破 ROS 和 ET-1 之间的循环是否会减轻 OSA 28 天后大鼠动脉和小动脉的脑血管功能障碍。 (SA2) 确定通过阻断内皮素受体来打破 ROS 和 ET-1 之间的循环是否会减轻 OSA 28 天后大鼠动脉和小动脉的脑血管功能障碍。 (SA3) 确定 28 天的 OSA 是否会降低 CBF、减弱 CBF 对胡须刺激的反应、减弱自动调节或减弱 CBF 对高碳酸血症的反应。确定减少 ROS 和/或阻断内皮素受体是否可以恢复体内这些反应。我们将使用孤立的加压脑动脉和小动脉以及放射自显影技术和激光多普勒血流测定法测量 CBF 来完成这些具体目标。这些研究的完成将使我们更好地了解脑血管功能障碍的潜在机制，并采取更有效的治疗方法来减少 OSA 对脑循环的破坏性影响，从而降低中风的发病率和痴呆的严重程度。