Cardiometabolic Consequences of the Loss of Ovarian Function

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PROJECT SUMMARY/ABSTRACT Menopause accelerates cardiovascular disease (CVD) risk due to changes in the hormone environment and adverse changes in cardiometabolic function. The overarching objective of the Colorado SCORE is to advance scientific knowledge of the impact of gonadal aging on the regulation of bioenergetics, abdominal adiposity and cardiometabolic function. We have shown that age-associated vascular endothelial dysfunction, a key antecedent for the development of CVD, is accelerated with gonadal aging in women. We also demonstrated that the menopausal-related decline in estradiol (E2) triggers the development of oxidative stress-mediated endothelial dysfunction. Endothelial function, measured by brachial artery flow- mediated dilation (FMD) decreased with short-term ovarian suppression (via gonadotropin releasing hormone antagonist, GnRHANT) in premenopausal women and this was reversed with E2 add-back. Prior SCORE research demonstrated that long-term ovarian suppression results in a marked increase in abdominal adiposity, particularly visceral, that is prevented by E2. How these adverse changes in adiposity influence vascular aging with E2 deficiency is unknown. Additionally, the mechanisms underlying the increased adiposity and impaired endothelial function in response to the withdrawal of E2 are not completely understood. Emerging evidence links the tryptophan-kynurenine (TRP-KYN) pathway to the regulation of vascular function, adiposity, and the aging process. Our preliminary data in men suggest that increased plasma KYN is associated with increased adiposity and endothelial dysfunction in older men with low testosterone. It is unknown if E2 regulates the TRP-KYN pathway in vascular and adipose tissues. Accordingly, Aim 1 will investigate the impact of increased abdominal visceral adiposity superimposed on the effects of E2 withdrawal on endothelial function. FMD and visceral fat area will be assessed before and after ovarian suppression with randomization to either E2 or placebo add-back. In collaboration with Projects 2 and 3, Aim 2 will determine if tissue-specific alterations in the TRP-KYN pathway are mechanistically linked to increased adiposity and endothelial dysfunction with E2 withdrawal. TRP-KYN metabolites and key enzymes in the pathway will be measured in blood, peripheral vascular endothelial cells, adipose tissue and isolated adipocytes acquired before and after the intervention. In collaboration with Projects 2 and 3, an Exploratory Aim will further examine the mechanistic role of TRP-KYN metabolism with E2 suppression on endothelial function using an ex vivo serum exposure cell culture model and by conducting vasodilation studies of arteries from animals in projects 2 and 3 with varying E2 status. Collectively, Project 1 will provide unique mechanistic insight by which acute and more chronic loss of ovarian function contributes to increased adiposity and endothelial dysfunction and will identify novel therapeutic targets to attenuate/prevent menopause-related cardiometabolic dysfunction and reduce the risk of CVD.