Multiple mechanisms of TRPV1-mediated brain protection following stroke

TRPV1介导的中风后脑保护的多种机制

• 批准号: 9551722
• 负责人: Sean P Marrelli
• 金额: $ 23.78万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-03-01 至 2021-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9551722
• 关键词: Adjuvant; Adult; Affect; Agonist; Area; Blood - brain barrier anatomy; Blood Vessels; Blood flow; Body Temperature; Brain; Brain Injuries; Brain region; Capsaicin; Cause of Death; Cerebrovascular Circulation; Cerebrum; Chemosensitization; Conscious; Contralateral; Data; Defense Mechanisms; Doppler Echocardiography; Dose; Endothelium; Evaluation; Health; Hemorrhage; Histology; Immunofluorescence Immunologic; Ipsilateral; Ischemia; Knock-out; Knockout Mice; Lasers; Lead; Measurement; Measures; Mediating; Methods; Modeling; Modification; Mus; Oxidants; Oxidative Stress; Perfusion; Pharmacology; Phase; Preparation; Reactive Oxygen Species; Reducing Agents; Reperfusion Therapy; Role; Stroke; System; TRPV1 gene; Temperature; Testing; Therapeutic; Transgenic Mice; Transgenic Organisms; Vanilloid; Vasodilation; aged; arm; behavior test; cerebral artery; cerebral microvasculature; cerebrovascular; disability; experimental study; hypoperfusion; improved; in vivo; induced hypothermia; injured; middle cerebral artery; natural hypothermia; neuroprotection; novel; pressure; protective effect; receptor; response; restoration; sex; stroke treatment; tool

Stroke is a significant health problem with limited treatment options. In this application, we present a new model in which activation of transient receptor potential vanilloid 1 (TRPV1) channels provides neuroprotection following ischemia/reperfusion (I/R) through two independent yet additive mechanisms. First, we provide evidence that pharmacological activation of vascular TRPV1 channels during the reperfusion phase selectively restores cerebral perfusion to the damaged brain regions. The hypoperfusion which occurs in damaged brain during early reperfusion can be dramatically and quickly restored without affecting the flow in non-injured brain regions. We propose that reactive oxygen species (ROS) produced following stroke lead to increased TRPV1 channel sensitivity to agonists, and thus the increased cerebral blood flow response. Second, activation of TRPV1 channels in the thermoregulatory system produces a rapid and sustainable decrease in body temperature (mild hypothermia) that is neuroprotective. In this context, TRPV1 activation effectively lowers the body's temperature “set point”, allowing for a more rapid and controlled level of therapeutic hypothermia to be achieved. We have already established that pharmacological activation of TRPV1 channels (“TRPV1 agonism”) is neuroprotective. While part of the neuroprotective effect is through induction of mild hypothermia, our new studies indicate that an additional protective effect may be through restoration of flow to hypoperfused brain regions. We now propose the overall hypothesis that TRPV1 agonism provides two arms of protection following stroke by 1) improving reperfusion in injured brain regions and 2) promoting protective hypothermia. We will study these mechanisms separately and then in combination to determine the additive benefit following stroke in adult and aged mice of both sexes. In aim 1, we will demonstrate selective increase in cerebral blood flow within the ischemia/reperfusion territory with TRPV1 agonism. These studies include in vivo cerebral blood flow measurements in adult and aged mice of both sexes following stroke. In aim 2, we will determine the role of ROS in potentiating endothelial TRPV1- mediated vasodilation and increased cerebral blood flow using isolated cerebral arteries and in vivo preparations. We will use a combination of pharmacological approaches, available knockout/transgenic mice, and a novel knockout mouse to demonstrate the specific role of endothelial TRPV1 channels and NOX-derived ROS in the mechanism. In aim 3, we will demonstrate the long-term neuroprotective benefit of TRPV1 agonism following stroke. We will evaluate the vascular component alone (hypothermia-independent mechanism) as well as the combined vascular and hypothermic components (hypothermia-dependent mechanism). Aged mice of both sexes will be evaluated by behavioral testing, histology, and blood brain barrier function during the course of one month of reperfusion. All together, these studies should establish TRPV1 agonism as a multi-faceted approach to neuroprotection following stroke.

中风是一种严重的健康问题，治疗选择有限。在此应用中，我们提出了一个新模型 其中瞬时受体电位香草酸 1 (TRPV1) 通道的激活可提供以下神经保护作用 通过两种独立但相加的机制实现缺血/再灌注（I/R）。首先，我们提供证据表明 再灌注阶段血管 TRPV1 通道的药理学激活选择性恢复 受损大脑区域的脑灌注。早期受损大脑中发生的灌注不足 再灌注可以显着且快速地恢复，而不影响未受伤大脑区域的血流。我们 提出中风后产生的活性氧 (ROS) 会导致 TRPV1 通道增加 对激动剂的敏感性，从而增加脑血流反应。二、TRPV1的激活 体温调节系统中的通道会产生快速且可持续的体温下降（轻度 低温）具有神经保护作用。在这种情况下，TRPV1激活可以有效降低体温 “设定点”，允许实现更快速和受控的治疗性低温水平。 我们已经确定 TRPV1 通道的药理学激活（“TRPV1 激动”）是 神经保护作用。虽然部分神经保护作用是通过诱导轻度低温实现的，但我们的新方法 研究表明，额外的保护作用可能是通过恢复低灌注大脑的血流来实现的 地区。我们现在提出总体假设，即 TRPV1 激动剂提供以下两种保护： 通过 1) 改善受损大脑区域的再灌注和 2) 促进保护性低温来预防中风。我们将 分别研究这些机制，然后结合起来确定中风后的附加益处 在成年和老年的两性小鼠中。 在目标 1 中，我们将证明缺血/再灌注区域内脑血流量的选择性增加 具有 TRPV1 激动作用。这些研究包括成年和老年小鼠的体内脑血流量测量 中风后的男女。在目标 2 中，我们将确定 ROS 在增强内皮 TRPV1 中的作用 使用分离的脑动脉和体内制剂介导血管舒张和增加脑血流量。 我们将结合使用药理学方法、现有的敲除/转基因小鼠和一种新型的 敲除小鼠以证明内皮 TRPV1 通道和 NOX 衍生的 ROS 在 机制。在目标 3 中，我们将证明 TRPV1 激动剂的长期神经保护作用 中风。我们将单独评估血管成分（与低温无关的机制）以及 结合血管和低温成分（低温依赖性机制）。两只老年小鼠 在一个过程中，将通过行为测试、组织学和血脑屏障功能来评估性别 再灌注月。总而言之，这些研究应该将 TRPV1 激动剂确立为一种多方面的方法 中风后的神经保护。