Neural & Vascular Dysfunction As Mechanisms of Injury in Genetic Migraine Models

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DESCRIPTION (provided by applicant): Migraine is often a chronic and progressive disorder with important hormonal, vascular and genetic modulating factors. Among the important experimental advances has been the development of mouse models of migraine expressing human mutations in implicated genes, as well as data implicating cortical spreading depression (CSD) in migraine aura. Preliminary data show that mouse models with mutations in genes implicated in severe and progressive migraine are more susceptible to CSD as well as to stroke. Furthermore, sex modulates CSD susceptibility in female mutant mice that is lost after gonadectomy or when estrus cycling ceases. Particularly underappreciated is that migraineurs are more susceptible to white matter changes and are at higher risk for stroke, and that vascular as well as brain parenchymal mechanisms are important to migraine pathophysiology. This application proposes to examine important questions about mechanisms of migraine aura that are relevant to understand the susceptibility for increasing headache frequency and progression (see RFA). Aim 1 will test the hypothesis that CSD susceptibility is increased by mutations linked to migraine (2 mutations in the 11A subunit of CaV2.1 channel, and in the blood vessel specific Notch3 receptor), further supporting the notion that CSD susceptibility is a common pathophysiological mechanism. Aim 1 also proposes to test whether female mice harboring mutations in two different genes (CaV2.1 and Notch3) and in two distinct loci in the CaV2.1 channel are more susceptible to CSD compared to males and whether enhanced susceptibility in females is sex hormone but not gender specific. Aim 2 will attempt to establish a link between these mutations implicated in migraine, and susceptibility to stroke and white matter lesions. We will test the hypothesis that vascular and metabolic mechanisms linked to increased CSD susceptibility promote greater flow- metabolism mismatch in mutants than in controls, as determined using novel optical imaging methods (CBF, oxygenation), autoradiography, and molecular stress markers. Aim 3 will further study these mutations by testing the hypothesis that CSD susceptibility conferred by genetic mechanisms renders the brain more sensitive to the development of stroke, and of white matter lesions in the presence of mild ischemia. Taken together these experiments are intended to examine mechanisms underlying progression of migraine and its neuropathological consequences. Migraine is a highly prevalent neurological disorder that is clinically associated with increased risk of brain injury such as stroke. This research will help identify the mechanisms by which risk factors for migraine predispose individuals to stroke and other types of brain injury, and open new avenues of research to prevent these long term progressive and cumulative complications of migraine.