Cortical-meningeal interactions underlying migraine headache

偏头痛是世界范围内导致残疾的主要原因之一。对许多人来说，现有的治疗方法仍然难以捉摸。 患者，并且由于不完全理解，新的治疗方法的开发受到限制 偏头痛的发病机制。 现在大量的研究支持偏头痛涉及 支配脑膜及其相关大血管的三叉神经感觉系统，但它仍然是 不清楚这个感觉系统是如何被激活的 在偏头痛发作期间。一个主要的证据是 指出了皮质功能障碍在引发偏头痛中的作用，并得到以下研究结果的支持， 皮层扩散性抑制（CSD）可引起脑膜神经元的激活和敏化 伤害感受通路然而，CSD被认为只在一小部分攻击中引发头痛， 都伴随着光环无先兆偏头痛也有感觉皮层过度兴奋的记录。 然而，目前还不清楚这种皮质功能障碍，除了CSD，是否以及如何可能导致脑膜炎， 伤害感受和随之产生的头痛。（i）皮质过度兴奋可以驱动 皮质星形胶质细胞通过其不同的GPCR的异常激活，和（ii）这将导致过度的 许多具有痛觉特性的星形胶质细胞因子的释放可以传播到脑膜中， 假设与CSD无关的皮质星形胶质细胞GPCR相关信号的增强足以驱动 脑膜感觉通路 .为了检验我们的工作假设，我们将首先确定是否选择性 感觉皮层星形胶质细胞Gq-和Gi-GPCR途径的激活足以驱动脑膜伤害感受器， 以及增强的星形胶质细胞GPCR相关 Ca 2+信号传导起作用（目的1）。然后我们将检查 这种增强的皮质星形胶质细胞信号传导是否也能促进偏头痛样疼痛行为（Aim 2）。 由于降钙素基因相关肽（CGRP）是关键参与偏头痛的病理生理，但它的作用， 我们将进一步测试皮层星形胶质细胞介导的脑膜伤害性感受是否 反应和相关的偏头痛行为表型涉及颅内内的外周CGRP信号传导 硬脑膜（Aim 3）。为了解决这些研究问题，我们将采用最先进的化学遗传学 DREADD（“设计师受体专门由设计师药物激活”）工具以及光遗传学， 选择性地促进星形胶质细胞GPCR途径的激活。我们将联合收割机这些方法与体内 细胞外单单位记录、双光子钙成像、行为方法以及遗传方法 操作，以询问增强的感觉皮层Gq-和Gi-的脑膜伤害性后果， 连接的Ca 2+信号。综上所述，我们提出的研究可以揭示星形胶质细胞GPCR信号的增加 作为偏头痛发作中感觉皮层过度兴奋和头痛发生的关键机制， 不涉及CSD和Aura。

Migraine is one of the top leading causes of disability worldwide. Existing treatments remain elusive for many patients, and development of novel treatments approaches has been limited due to the incomplete understanding of migraine pathogenesis. A large body of work now supports the notion that migraine headache involves the trigeminal sensory system that innervates the cerebral meninges and their related large vessels, but it remains unclear how this sensory system becomes activated during a migraine attack. One leading line of evidence points to the role of cortical dysfunction in triggering migraine headache, and is supported by the findings that cortical spreading depression (CSD) can cause the activation and sensitization of neurons in the meningeal nociceptive pathway. However, CSD is thought to trigger the headache in only the small subset of attacks that are accompanied by aura. Sensory cortex hyperexcitability has also been documented in migraine without aura. However, it is unclear whether and how such cortical dysfunction, beyond CSD, might lead to meningeal nociception and the ensuing generation of headache. The notions that (i) cortical hyperexcitability can drive abnormal activation of cortical astrocytes via their diverse GPCRs, and (ii) that this would result in excessive release of numerous astrocytic factors with algesic properties that can propagate into the meninges, has led us to hypothesize that heightened cortical astrocyte GPCR-linked signaling, unrelated to CSD, is sufficient to drive the meningeal sensory pathway . To test our working hypothesis, we will first determine whether selective activation of sensory cortical astrocyte Gq- and Gi-GPCR pathways are sufficient to drive meningeal nociceptors, and whether enhanced astrocytic GPCRR-linked Ca2+ signaling plays a role (Aim 1). We will then examine whether such enhanced cortical astrocyte signaling can also promote migraine-like pain behaviors (Aim 2). Because calcitonin gene-related peptide (CGRP) is critically involved migraine pathophysiology, but its role is still not well understood, we will further test whether the cortical astrocyte mediated meningeal nociceptive responses and related migraine behavioral phenotype involve peripheral CGRP signaling within the intracranial dura mater (Aim 3). To address these research questions, we will employ a state-of-the-art chemogenetic DREADD (“designer receptors exclusively activated by designer drugs”) tools, as well as optogenetics, to selectively promote activation of astrocyte GPCR pathways. We will combine these approaches with in vivo extracellular single-unit recording , 2-photon calcium imaging, behavioral approaches, as well as genetic manipulations to interrogate the meningeal nociceptive consequences of enhanced sensory cortical Gq- and Gi- linked Ca2+ signaling. Taken together, our proposed research could reveal increased astrocyte GPCR signaling as a key mechanism that links sensory cortex hyperexcitability and headache genesis in in migraine attacks that do not involve CSD and aura.