VOLTAGE-GATED CALCIUM CHANNELS IN MIGRAINE PATHOPHYSIOLOGY

描述(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。其发病机制可能与离子稳态异常和神经传递有关。CaV2.1是人类P/Q型电压门控钙通道(VGCC)的致孔亚单位，编码CaV2.1的基因的多个突变与家族性偏瘫1型偏头痛(FHM-1)有关，FHM-1是偏头痛的一个亚类，有先兆。许多偏头痛预防和流产药物可以调节VGCC的功能，但其特异性和有效性较差。该项目的总体目标是更好地了解个别VGCC亚型在偏头痛的病理生理学中的作用。此外，VGCC阻滞剂作为抗偏头痛治疗药物的潜力将得到直接测试。我们实验室最近的研究发现，功能丧失(LOF)CaV2.1突变导致三叉神经节(TG)和背根神经节所有亚型神经元的P/Q型电流减少和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异凝素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不是面部皮肤的小型IB4神经元的过度兴奋。这与以下事实一致：除偏头痛外，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阻滞剂对野生型小鼠进行预处理后，显著缩短了头痛小鼠模型中头部定向突触行为的持续时间，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，我们建议使用多学科的方法来研究多个VGCC调节硬脑膜传入神经元的兴奋性和突触传递，从而调节偏头痛回路的增益的机制。首先，我们将验证P/Q型钙通道通过钙激活的Tresk背景K+通道的功能偶联来调节小型IB4-硬脑膜传入神经元兴奋性的假说。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过度兴奋和抑制头痛样行为。其次，我们将利用光学成像技术来阐明N型和其他亚型VGCC在硬脑膜传入终末钙离子内流突触传递中的作用。最后，我们将使用头痛的小鼠模型来验证硬脑膜传入神经元中的N和T型VGCC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，该项目的成果将对VGCC在偏头痛病理生理学中的贡献以及三叉神经VGCC及其下游效应因子(S)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.