Investigation of the Modulators of Cerebrovascular Coupling

我们想了解脑卒中引起的皮质功能区的改变如何导致神经活动增加时血流动力学反应的改变。这将使我们能够完善的概念，血管系统的建立，以支持皮层的功能组织，并使开发一个更好的模型，推断有关的血流动力学反应的时空特征的仔细分析的神经元通信流。为此，我们将开发局灶性缺血模型的基础上，空间有针对性的应用血管收缩肽，如内皮素-1（ET-1），以测试相关性的不同子区域的皮质，特别是个别功能区（如个人的脸补丁或代表个别数字）在口述的时空特征的血流动力学反应。我们将使用皮质细胞结构的高分辨率MRI来计划和选择要缺血的皮质内的靶子域，并将缺血后的功能数据与缺血前从相同动物获得的数据进行比较。我们还将比较两种状态下获得的脑血管阻力和血管区域图。由于中风面积将变小，这些图可能不会改变，但由于中风引起的神经元细胞的区域选择性死亡，任务诱导的血流动力学反应将显著不同。这些实验将提供一个更好的理解血管树的架构如何影响血流动力学反应的时空特征。 我们使用自发性高血压大鼠（SHR）和其正常血压对照WKY评估皮质内注射ET-1的影响。ET-1在SHR中产生的梗死体积大于WKY。用JZL 184（一种酶单酰基甘油脂肪酶（MAGL）的强大且特异性的抑制剂）治疗动物的前和后均显著减少由ET-1诱导的梗死体积，从而确立MAGL作为中风的重要治疗靶点。此外，MAGL抑制显著改善缺血后的神经学结果。MAGL将脑中最丰富的内源性大麻素2-花生四烯酸甘油（2-AG）水解为花生四烯酸（AA），这是促炎性胡萝卜素和白三烯的重要前体。2-AG不仅通过调节大麻素受体的信号传导，而且通过控制AA的释放而表现出抗炎和神经保护特性。因此，我们假设MAGL抑制可能是神经系统疾病（包括缺血性卒中）的一种新的抗炎和神经保护策略。MAGL的抑制导致抑制神经炎症，如通过缺血核心中活化的小胶质细胞数量的显著减少所测量的。因此，我们的研究结果表明，MAGL单独有助于脑缺血的神经病理学，因此是一个有前途的治疗缺血性中风的治疗靶点。为了验证灵长类动物大脑中的工作，在绒猴中重现上述相同的实验将是令人兴奋的，我们打算在完成啮齿动物研究后立即进行。该研究报告现已提交出版，正在审查中。

We want to understand how alterations in cortical functional domains induced by stroke lead to changes in the hemodynamic response to increased neural activity. This will allow us to refine the notion that the cerebrovasculature is built to support the functional organization of the cortex, and enable development of a better model of inferring about the flow of neuronal communication from careful analysis of the spatiotemporal features of the hemodynamic response. For this, we will develop focal ischemic models based on spatially targeted applications of vasoconstricting peptides such as endothelin-1 (ET-1) to test the relevance of different sub-regions of the cortex and, in particular, of individual functional areas (e.g. individual face patches or the representation of individual digits) in dictating the spatiotemporal characteristics of the hemodynamic response. We will use high-resolution MRI of the cortical cytoarchitecture to plan and chose the target sub-domains within the cortex to be made ischemic, and compare the post-ischemia functional data with those obtained from the same animals pre-ischemia. We will also compare cerebrovascular resistance and vascular territory maps obtained at both states. Because the stroke area will be made small, it is possible that these maps will not change, but task-induced hemodynamic responses will be significantly different due to the region-selective death of neuronal cells caused by stroke. These experiments will provide a better understanding of how the architecture of the vascular tree influences the spatiotemporal features of the hemodynamic response. We used the spontaneously hypertensive rat (SHR) and its normotensive control WKY to evaluate the effects of an intracortical injection of ET-1. ET-1 produces a larger infarct volume in SHR than in WKY. Both pre- and post-treatment of the animals with JZL184, a powerful and specific inhibitor of the enzyme monoacylglycerol lipase (MAGL) significantly reduces the infarct volume induced by ET-1, thus establishing that MAGL as an important therapeutic target for stroke. In addition, MAGL inhibition significantly improved neurological outcome post-ischemia. MAGL hydrolyzes 2-arachidonoyl glycerol (2-AG), the most abundant endogenous cannabinoid in the brain, into arachidonic acid (AA), an important precursor of pro-inflammatory prostaglandins and leukotrienes. 2-AG exhibits anti-inflammatory and neuroprotective properties not only through modulating the signaling of cannabinoid receptors, but also by controlling AA release. Thus we hypothesized that MAGL inhibition might be a novel anti-inflammatory and neuroprotective strategy for neurological disorders, including ischemic stroke. Inhibition of MAGL leads to suppressed neuroinflammation, as measured by a significant reduction in the number of activated microglia in the ischemic core. Thus, our results suggest that MAGL alone contributes to neuropathology of cerebral ischemia, and thus is a promising therapeutic target for the treatment of ischemic stroke. To validate the work in the primate brain, it will be exciting to reproduce the same above experiments in marmosets, and we intend to do so just as soon as we finish the rodent study. This study is now submitted for publication and is under review.