VOLTAGE-GATED CALCIUM CHANNELS IN MIGRAINE PATHOPHYSIOLOGY

描述（由申请人提供）：偏头痛是最常见的神经血管疾病之一。它使人非常虚弱，而且很难治疗。其发病机制可能与异常的离子稳态和神经传递有关。编码人类P/ q型电压门控Ca2+通道（VGCC）的孔隙形成亚基CaV2.1基因的多个突变与家族性偏瘫偏头痛1型（FHM-1）有关，这是一种先兆偏头痛的亚类。许多偏头痛预防和流产药物可调节vgc的功能，但特异性和有效性较差。该项目的总体目标是更好地了解单个VGCC亚型对偏头痛病理生理的贡献。此外，VGCC阻滞剂作为抗偏头痛药物的潜力将被直接测试。我们实验室最近的研究发现，在三叉神经节（TG）和背根神经节神经元的所有亚型中，功能缺失（LOF） CaV2.1突变导致P/Q型电流降低和n型VGCC电流代偿性增加。有趣的是，LVA t型VGCC电流的选择性增加只发生在不与隔离素B4 （IB4-）结合的小直径TG神经元中。此外，LOF CaV2.1突变导致支配硬脑膜而非面部皮肤的IB4-小神经元的高兴奋性。这与事实是一致的，除了偏头痛，FHM-1患者没有表现出更高的其他躯体或口面部疼痛的发生率。重要的是，用T型或n型VGCC阻滞剂预处理野生型小鼠，可显著减少小鼠头痛模型中头部导向的有害行为持续时间，这表明VGCC参与了偏头痛背后的神经元回路的激活。在这个项目中，我们建议采用多学科方法来研究多个vgc调节硬脑膜传入神经元的兴奋性和突触传递的机制，从而调节偏头痛回路的增益。首先，我们将验证P/ q型Ca2+通道通过Ca2+激活的TRESK背景K+通道的功能偶联调节小IB4-硬膜传入神经元的兴奋性的假设。我们将在小鼠模型中研究增强TRESK通道活性是否可以逆转硬脑膜传入神经元的超兴奋性并抑制头痛样行为。其次，我们将使用光学成像技术来阐明n型和其他亚型VGCCs对硬脑膜传入末端Ca2+内流突触传递的贡献。最后，我们将使用小鼠头痛模型来验证硬脑膜传入神经元中的N型和t型vgc是抗偏头痛治疗的潜在靶点的假设。我们将测试N型和t型阻滞剂是否可以用于偏头痛的流产和预防治疗。综上所述，本项目的结果将为vgc对偏头痛病理生理的贡献以及三叉神经vgc及其下游效应物在偏头痛治疗和预防中的治疗潜力提供新的见解。

DESCRIPTION (provided by applicant): Migraine is one of the most common neurovascular disorders. It is highly debilitating and difficult to treat. The disease mechanisms may involve abnormal ion homeostasis and neurotransmission. Multiple mutations in the gene encoding CaV2.1, the pore-forming subunit of human P/Q-type voltage-gated Ca2+ channel (VGCC), have been associated with familial hemiplegic migraine type 1 (FHM-1), a subclass of migraine with aura. Many of the migraine preventive and abortive drugs modulate the function of VGCCs but with poor specificity and efficacy. The overall goal of this project is to better understand th contribution of individual VGCC subtypes to the pathophysiology of migraine headache. In addition, the potential of VGCC blockers as anti-migraine therapeutics will be directly tested. Recent studies from our lab have found that loss-of-function (LOF) CaV2.1 mutations cause a decrease of P/Q- type current and a compensatory increase in N-type VGCC current in all subtypes of trigeminal ganglion (TG) and dorsal root ganglion neurons. Interestingly, a selective increase in LVA T-type VGCC current occurs only in small-diameter TG neurons that do not bind to isolectin B4 (IB4-). Moreover, LOF CaV2.1 mutations results in hyper-excitability of small IB4- neurons innervating the dura but not the facial skin. This is consistent with the fact that, other than migraine headache, FHM-1 patients do not show higher incidence of other somatic or orofacial pain. Importantly, pretreatment of wild-type mice with T- or N-type VGCC blockers significantly reduced the duration of head-directed nocifensive behavior in a mouse model of headache, indicating that VGCCs are involved in the activation of the neuronal circuit underlying migraine headache. In this project we propose to employ a multidisciplinary approach to investigate the mechanisms through which multiple VGCCs regulate the excitability and synaptic transmission of dural afferent neurons, thereby modulating the gain of the migraine circuit. First, we will test the hypothesis that P/Q-type Ca2+ channels regulate the excitability o small IB4- dural afferent neurons via functional coupling of the Ca2+-activated TRESK background K+ channels. We will investigate whether enhancing TRESK channel activity can reverse the hyper-excitability of dural afferent neurons and inhibit headache-like behavior in a mouse model. Secondly, we will use optical imaging technique to elucidate the contribution of N-type and other subtypes of VGCCs to Ca2+ influx synaptic transmission at dural afferent terminals. Finally, we will use a mouse model of headache to test the hypothesis that N- and T-type VGCCs in dural afferent neurons are potential targets for anti-migraine therapeutics. We will test whether N- and T-type blockers can be used for both abortive and preventive therapy of migraine headache. Taken together, the outcome of this project will offer new insights into the contribution of VGCCs to migraine pathophysiology as well as the therapeutic potential of trigeminal VGCCs and their downstream effector(s) in migraine treatment and prevention.