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Background: Vascular cognitive impairment and dementia (VCID) is the second most common form of dementia after Alzheimer’s disease (AD). Currently, the mechanistic insights into the evolution and progression of VCID are not fully understood. White matter change represents an invariant feature of both VCID and AD. Compelling clinical neuroimaging and pathological evidence suggest a link between white matter changes and neurodegeneration. Our prior study detected non-perfusion lesions in mice with partial deficiency of endothelial nitric oxide (eNOS) expression at a very young age. These lesions developed in multiple brain regions in an age-dependent manner, precisely matching to those hypoperfused areas identified in preclinical AD patients (ie, temporoparietal and retrosplenial granular cortexes, and hippocampus). We therefore reasoned that eNOS-deficient mice could serve as a spontaneous model of chronic hypoperfusion.

Methods/Results: White matter tracts are particularly susceptible to the vascular damage induced by chronic hypoperfusion. Using immunohistochemistry, we detected massive demyelination in the middle aged eNOS-deficient mice. The demyelinated areas were confined to cortical and subcortical areas including the corpus callosum and hippocampus, but did not involve the striatum. The intensity of demyelination correlated with behavioral gait deficits. By Evans blue angiography, we detected blood-brain barrier (BBB) leakage as another early pathological change affecting frontal and parietal cortex in eNOS-deficient mice, which occurs in as early as 3-4 months of age. Sodium nitrate fortified drinking …