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 AMPKα 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 AMPKα1, 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.