Multiple mechanisms of TRPV1-mediated brain protection following stroke

中风是一个严重的健康问题，治疗选择有限。在这个应用中，我们提出了一个新的模型 其中激活瞬时受体电位香草素1(TRPV1)通道提供神经保护 缺血/再灌注(I/R)通过两种独立但相加的机制。首先，我们提供证据证明 血管TRPV1通道在再灌注期的药理激活选择性恢复 脑血流灌注到受损的脑区。脑损伤早期出现的低灌注率 再灌注可以显著而快速地恢复，而不会影响非损伤脑区的血流。我们 认为卒中后产生的ROS导致TRPV1通道增加 对激动剂的敏感性，因此增加了脑血流反应。第二，激活TRPV1 体温调节系统中的通道产生快速且可持续的体温下降(温和 体温过低)，这是神经保护。在这种情况下，TRPV1的激活有效地降低了人体的温度 “设定点”，可实现更快、更可控的治疗性低温。 我们已经证实，TRPV1通道的药理激活(“TRPV1激动剂”)是 具有神经保护作用。虽然部分神经保护作用是通过诱导亚低温来实现的，但我们新的 研究表明，另一种保护作用可能是通过恢复脑血流至低灌注区。 地区。我们现在提出的总体假设是，TRPV1激动剂在下列情况下提供了两个保护臂 卒中通过1)改善受损脑区的再灌注和2)促进保护性低温。我们会 单独研究这些机制，然后结合起来确定中风后的附加益处 在成年和老年小鼠中，无论性别。 在目标1中，我们将展示脑缺血/再灌注区内脑血流量的选择性增加。 伴有TRPV1激动剂。这些研究包括成年和老年小鼠的活体脑血流量测量。 中风后的男性和女性。在目标2中，我们将确定ROS在增强内皮TRPV1- 使用分离的大脑动脉和体内制剂介导血管扩张和增加脑血流量。 我们将结合使用药理学方法、现有的基因敲除/转基因小鼠和一种新的 基因敲除小鼠演示内皮细胞TRPV1通道和NOX衍生的ROS在 机制。在目标3中，我们将展示TRPV1激动剂的长期神经保护作用 卒中。我们将单独评估血管组件(低温非依赖机制)以及 结合血管和低温成分(低温依赖机制)。两种衰老小鼠 性别将通过行为测试、组织学和血脑屏障功能在一个疗程中进行评估 再灌流一个月。总之，这些研究应该建立TRPV1激动剂作为一种多方面的方法。 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.