Contrary to conferring cardioprotection in male animals, acute ethanol causes estrogen (E2)-dependent myocardial depression in females. Despite progress made during the previous award, the molecular mechanisms for this health related problem remain unresolved. We hypothesize that E2-mediated accumulation of ethanol-derived acetaldehyde (ACA) creates environment conducive to paradoxical transformation of E2 into a pro-inflammatory hormone. We will focus on myocardial catalase and mitochondrial aldehyde dehydrogenase 2 (mit-ALDH2) because E2 enhancement of their physiological activity confers cardioprotection and both enzymes regulate myocardial ethanol-derived ACA balance;catalase catalyzes ethanol oxidation to ACA and mit-ALDH2 detoxifies ACA. We hypothesize that E2 enhancement of myocardial catalase activity could result in higher ethanol-derived ACA. Subsequently, competition of higher ACA level with more cytotoxic substrates for mit-ALDH2 leads to accumulation of cytotoxic aldehydes (oxidative stress and myocardial dysfunction). We further hypothesize that E2 mediates these cellular effects via nongenomic estrogen receptor (ER) signaling. To test our novel hypotheses, we will employ a multidisciplinary approach that encompasses integrative, cellular, molecular and pharmacological studies to address the following specific aims.
Aim 1 studies will test the hypothesis that enhancement of nongenomic rapid ER signaling mediates ethanol-evoked oxidative stress and myocardial depression in female rats.
Aim 2 studies will elucidate the role of ACA generating (ADH, catalase) and aldehyde detoxifying (mit-ALDH2) enzymes in the E2-dependent oxidative stress and myocardial depression caused by ethanol.
Aim 3 studies will test the novel hypothesis that ethanol/ACA- evoked eNOS/nNOS uncoupling plays pivotal role in the paradoxical transformation of E2 into proinflammatory hormone in the myocardium and vasculature. These studies will further our understanding of the molecular mechanisms for the E2-dependent myocardial dysfunction caused by acute alcohol and will allow identification of novel targets for new interventions for the treatment/prevention of cardiovascular anomalies caused by alcohol in females.
Given the steady rise in acute alcohol consumption by young women, the proposed research is clinically relevant because it: (i) elucidates how estrogen transforms ethanol-evoked cardio-protection into cardiodepression in females;(ii) identifies alcohol use as potential contributor to the disappointing outcomes with estrogen in clinical studies;(iii) identifies the estrogen receptor subtype(s) implicated in the higher physiological activity of the cardioprotective enzyme, myocardial mit-ALDH2 in females.
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