Multiple mechanisms of TRPV1-mediated brain protection following stroke

中风是一种严重的健康问题，治疗选择有限。在这个应用中，我们提出了一个新的模型， 其中瞬时受体电位香草酸1（TRPV 1）通道的激活提供了神经保护， 缺血/再灌注（I/R）通过两种独立但叠加的机制。首先，我们提供证据， 再灌注期血管TRPV 1通道的药理学激活选择性地恢复了 受损脑区的脑灌注。脑损伤早期出现的低灌注， 再灌注可以显著和快速地恢复，而不影响未受伤的脑区域中的流动。我们 提出中风后产生的活性氧（ROS）导致TRPV 1通道增加 对激动剂的敏感性，从而增加脑血流反应。第二，TRPV 1的激活 体温调节系统中的通道产生体温的快速和可持续的降低（轻度 低温），这是神经保护。在这种情况下，TRPV 1的激活有效地降低了体温 “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TRPV 1通道的药理学激活（“TRPV 1激动作用”）是一种重要的机制。 神经保护虽然部分神经保护作用是通过诱导轻度低温，但我们的新研究表明， 研究表明，另外的保护作用可能是通过恢复低灌注脑的血流 地区我们现在提出了一个总体假设，即TRPV 1激动剂在以下情况下提供了两种保护作用： 通过1）改善受损脑区的再灌注和2）促进保护性低温来治疗中风。我们将 分别研究这些机制，然后结合起来，以确定中风后的附加效益 在成年和老年小鼠的两种性别。 在目标1中，我们将证明在缺血/再灌注区域内选择性增加脑血流量 TRPV 1激动剂。这些研究包括成年和老年小鼠的体内脑血流量测量 中风后的男女性。在目标2中，我们将确定ROS在增强内皮TRPV 1 - 1中的作用。 介导的血管舒张和增加脑血流量使用分离的脑动脉和体内制剂。 我们将结合药理学方法、现有的基因敲除/转基因小鼠和一种新的 敲除小鼠，以证明内皮TRPV 1通道和NOX衍生的ROS在 机制在目标3中，我们将证明TRPV 1激动剂在以下情况下的长期神经保护益处： 中风我们将单独评估血管成分（不依赖于低血糖的机制）以及 结合血管和低体温成分（低体温依赖性机制）。老年小鼠 性别将通过行为测试、组织学和血脑屏障功能进行评估， 再灌注一个月。总之，这些研究应该建立TRPV 1激动作为一个多方面的方法 中风后的神经保护

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.