Ovarian Hormone Regulation of Central and Cerebrovascular Hemodynamics

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PROJECT SUMMARY Alzheimer's disease (AD) is a major cause of morbidity and mortality in older adults that disproportionately affects women. There are no effective treatments for AD in part because sex-differences in the pathophysiology of AD remain unclear. However, increasing evidence supports the early role of extracerebral (e.g., central artery stiffness) and intracerebral (e.g., reductions in cerebral blood flow and endothelial function) vascular and mitochondrial dysfunction in the development of AD neuropathology. Menopause is associated with increased oxidative stress and accelerated vascular aging with the loss of estrogen suggesting that women may have an increased vascular contribution to the development of AD. The overall goal of this research project is to investigate the role of declines in estrogen on the vascular contribution to brain aging in women, and the underlying mechanism related to increased mitochondrial oxidative stress. {In humans,} we will use both cross-sectional and intervention study designs to isolate the effects of estrogen deficiency on changes in extra- and intra-cerebral vascular function in women. Healthy, pre- and post-menopausal women without cognitive impairment will undergo baseline vascular testing. Additionally, premenopausal will undergo 12-weeks of gonadal suppression to temporarily and reversibly suppress ovarian hormones to investigate the early vascular changes associated with estrogen deficiency. {To isolate changes in mitochondrial and cerebrovascular function with estrogen deficiency, cerebral arterioles will be obtained from female ovariectomized rats treated with degarelix and randomized to receive estrogen or placebo add-back for 10- weeks. Cerebral endothelium-dependent and protein markers of mitochondrial function will be measured in isolated cerebral arterioles.} Results of the proposed study will provide mechanistic insight into sex-differences in AD risk in women and may inform novel future therapeutic targets for preventing or slowing the onset of AD in women. The applicant, Dr. Lyndsey DuBose, received graduate training in the extracerebral vascular contributions to cognitive aging in humans at the University of Iowa. Dr. DuBose and her mentoring team have developed a training plan that builds on her previous experiences to develop new skills in women's vascular health. Dr. DuBose's training objectives are to obtain: 1) didactic training in clinical trial design, bioimaging, advanced biostatistics, and reproductive endocrinology; 2) experience in conducting mechanistically-driven human clinical translational research; 3) {develop basic science skills for the first time including the measurement of mitochondrial and vascular function in female rats}; 4) produce several first-authored publications and improve her grant writing skills in pursuit of becoming an independent clinical researcher in women's cardiovascular and cerebrovascular aging.