Growing evidence supports the concept that Alzheimer?s disease (AD) is fundamentally a metabolic/cerebro- microvascular disease with molecular/biochemical features that correspond with diabetes mellitus (DM). Cerebrovascular endothelial dysfunction is emerging as a major risk factor for AD. Importantly, SK/IK channels have been reported to play a key role for neurodegeneration and cerebrovascular regulation. However, mechanisms and the therapeutic strategies for endothelial SK/IK channels to mitigate metabolic and cerebrovascular disturbances in AD are lacking. Thus, the overall goal of this supplement project is focused on the mechanism and treatment of endothelial SK/IK channel modulation on AD-induced neurovascular dysfunction. We observed that amyloid-?(A?) peptide (A?) causes endothelial SK/IK dysfunction. Thus, we hypothesized that AD may cause metabolic dysregulation of SK/IK channel function, leading to cerebrovascular endothelial dysfunction and neurovascular injury; and metabolic modulation and/or SK/IK activation will enhance cerebrovascular SK/IK activity leading to normalized neurovascular endothelial function/relaxation. Importantly, this is the same basic hypothesis as in the parent R01 grant focused on metabolic modulation in coronary endothelium and microvasculature. We will use the same approaches, specialized reagents, and similar experimental strategies as detailed in my current RO1 to complete the Aims of this supplement proposal. Thus, we will test our hypothesis by completing 2 specific aims: Ami 1) to evaluate if metabolic modulation and/or SK/IK activation can alleviate A?-induced changes in SK/IK channel activity in the in-vitro. Brain microvascular endothelial cells with or without DM will be treated with soluble A? in the presence/absence of PKC, Nox, mROS inhibitors, NADH/NAD, SK/IK small molecule activators, adenoviral overexpression/mutation of endothelial SK/IK, respectively. Endothelial SK/IK channel recording (patch clamp method) and metabolic alterations will be assessed.
Aim 2) to Determine AD-induced changes in cerebra-microvascular reactivity, SK/IK activation-induced endothelium-dependent cerebral arteriolar relaxation and if metabolic modulation and/or SK/IK-activator can improve cerebra-microvascular reactivity and cognitive function in the STZ-induced AD mice and STZ-treated SK/IK KO mice. We will treat STZ-induced AD mice and STZ treated SK/IK knockout (KO) mice with/without Nox, mROS, PKC inhibitors, SK/IK activators, respectively for 4 weeks followed by Morris Water Maze testing for cognitive function and assessment of neurovascular morphologic/metabolic changes. We will harvest cerebral arterioles from WT mice and STZ-induced-AD mice and STZ-treated SK/IK KO mice for analyzing cerebral arteriolar reactivity and SK/IK activity. This project will improve our understanding of AD-related cerebrovascular dysfunction by studying novel mechanisms responsible for metabolic dysregulation of endothelial SK channels and cerebrovascular function, and lead to novel approaches for improving cerebro-microvascular function in AD and other cerebral small vessel disease.
The overall goal of this supplement proposal is to understand how Alzheimer?s dysregulation SK/IK channels and cerebrovascular endothelial function and to investigate how metabolic modulation of endothelial SK/IK function in cerebrovascular protection. This project will increase our understanding of the paradigm shifting mechanisms responsible for metabolic modulation of cerebral endothelial SK/IK channel function, cerebral microcirculatory function and neuronal/neurovascular protection in Alzheimer?s? disease and/or cerebral small artery disease.
