MECHANISMS OF CSD-EVOKED PERSISTENT ACTIVATION OF MENINGEAL NOCICEPTORS

偏头痛是全球第二大致残原因；然而，目前尚不清楚头痛是如何 这个阶段是在偏头痛发作期间开始的。在有先兆的偏头痛中，大约30%的人会受到影响 对于偏头痛，主要的理论认为：(A)皮质扩散性抑制(CSD)是 作为先兆阶段基础的病理生理事件，以及b)CSD以某种方式导致 脑膜感觉系统，导致头痛发作。我们最近的研究，包括在 之前的资助期，通过最终表明CSD为该理论提供了长期缺失的关键支持 事实上确实激活了脑膜感觉传入，并能产生较长时间的激活和 机械敏化。然而，CSD理论的一个长期问题是缺乏 CSD会导致疼痛行为的证据，这在一个被认为是一种强有力的事件中是可以预料的 引发头痛。此外，在CSD和随后的脑膜传入之间建立联系的努力 反应和头痛一直受到脑膜活动研究挑战的限制。 清醒行为动物的感觉神经元。我们已经克服了这一主要障碍，制定了两项- 光子钙显像法监测清醒状态下脑膜传入神经末梢的活动 在通过慢性颅窗自愿移动的过程中，表现为老鼠。在目标1中，我们建议追求这一点 新的成像方法，以扩展初步数据表明，作为CSD诱导的结果 机械敏化，在自愿运动过程中脑膜拉伸导致增强激活 脑膜传入，以及随之而来的活动减少。目标2和3是探索细胞和 CSD后脑膜伤害性反应的分子机制。我们将在初步的基础上 结果并使用麻醉动物的电生理学，清醒小鼠的钙成像和光遗传学 皮质星形胶质细胞在调节脑膜强化中起因果作用的假设的检验方法 慢性阻塞性肺病患者自主活动的传入反应和相关减少。然后，我们将雇用 生物传感器、电生理学、传入钙成像、药物抑制剂和转基因小鼠 星形胶质细胞依赖的大脑皮层ATP外流参与CSD诱发脑膜伤害性反应的假说 通过脑膜巨噬细胞中的嘌呤能P2X7信号。这些创新的实验，除了 建立研究脑膜传入和相关反应的新的强大平台 与偏头痛有关的行为后果也可以阐明皮质星形胶质细胞的作用 和脑膜嘌呤能信号，以及导致偏头痛机制的性别差异 疼痛-缓解CSD对有先兆偏头痛的疼痛影响的关键一步。

Migraine is the second leading cause of disability worldwide; however, it remains unclear how the headache phase is initiated during a migraine attack. In migraine with aura, a condition that affects about 30% of people with migraine, the leading theory proposes that (a) cortical spreading depression (CSD) is the pathophysiological event that underlies the aura phase, and b) CSD somehow leads to the activation of the meningeal sensory system, resulting in the onset of the headache. Our recent studies, including during the prior grant period, provided a long-missing critical piece of support for the theory by finally showing that CSD does in fact activate meningeal sensory afferents, and can produce a prolonged period of both activation and mechanical sensitization. However, a long-standing problem with the CSD theory has been the paucity of evidence that CSD leads to pain behaviors, as would be expected for an event that supposedly is a potent trigger for headache. Furthermore, efforts to establish a link between CSD, the ensuing meningeal afferent responses, and headache pain have been limited by the challenges of studying the activity of meningeal sensory neurons in awake behaving animals. We have overcome this major obstacle by developing a two- photon calcium imaging approach to monitor the activity of meningeal afferent nerve endings in the awake behaving mouse, during voluntary locomotion via a chronic cranial window. In Aim 1, we propose to pursue this novel imaging approach to expand upon preliminary data suggesting that as a result of CSD-induced mechanical sensitization, meningeal stretching during voluntary locomotion results in enhanced activation of meningeal afferents, and consequent reduction of locomotion. Aims 2 and 3 are to explore cellular and molecular mechanisms that contribute to meningeal nociception following CSD. We will build upon preliminary results and use electrophysiology in anesthetized animals, calcium imaging in awake mice and an optogenetic approach to test the hypothesis that cortical astrocytes play a causal role in mediating the enhanced meningeal afferent responses and related decrease in voluntary locomotion following CSD. We will then employ biosensors, electrophysiology, afferent calcium imaging, pharmacological inhibitors and transgenic mice to test the hypothesis that astrocyte-dependent cortical ATP efflux contributes to CSD-evoked meningeal nociception via purinergic P2X7 signaling in meningeal macrophages. These innovative experiments, in addition of establishing a novel powerful platform for studying the responses of meningeal afferents and associated behavioral consequences related to migraine headache, could also shed light on the roles of cortical astrocytes and meningeal purinergic signaling, as well as sex differences in the mechanisms responsible for migraine pain - a key step towards mitigating the painful effects of CSD in migraine with aura.