Mechanisms of Chronic Remote Ischemic Conditioning Induced Cerebroprotection in a VCID Model

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The prevalence of dementia is expected to triple by 2050 making it a major threat to world public health. Vascular dementia makes up 20% of dementia cases and vascular causes contribute to another 30%. These vascular contributions to cognitive impairment and dementia are known by the acronym VCID. There is no known effective treatment for VCID; however observational studies strongly suggest that physical exercise is effective at reducing progression of cognitive decline and dementia. Chronic remote ischemic conditioning (C-RIC), is the repetitive inflation and deflation of a blood pressure cuff on the limbs for periods of weeks or months and may be an “exercise mimetic”. Our data in the VCID mouse model shows that C-RIC is cerebroprotective, increasing cerebral blood flow and collateral remodeling and improving cognition. Our central hypothesis is that C-RIC triggers a cerebroprotective phenotype by activation of peripheral limb AMPK and eNOS with an increase in circulating plasma nitrite and “endocrine NO activity” leading to increased CBF, angiogenesis, and collateral remodeling. Our sub-hypothesis is that these effects of C-RIC are age and sex independent. Our Specific aims are: Aim 1: Determine the critical role of eNOS in mediating C-RIC induced cerebroprotection and vascular remodeling upon eNOS. Aim 2: Determine the dependence of C-RIC cerebroprotection upon endothelial- specific AMPK1, an upstream regulator of eNOS. We will utilize an endothelial specific AMPKα mouse knockout (KO) model to determine whether RIC’s protection is dependent upon endothelial AMPKα1. Aim 3: Determine the role of bone marrow (BM) -derived cells in C-RIC-induced angiogenesis and collateral remodeling. eNOS in BM cells may be critical to the mechanism of C-RIC. These studies will help us to define the mechanism of C-RIC in cerebroprotection and help us translate C-RIC from the bench to the bedside in patients with VCID to reduce dementia.