Abdel A. Abdel-Rahman - US grants

A strong link has been established between alcohol intake and inadequate blood pressure control in treated hypertensives. Surprisingly, this problem has gained very little attention even though it involves a good proportion of treated hypertensives. Because recent evidence argues against the generally accepted mechanism of poor compliance with therapy as the main reason, other unidentified factors should be considered. It is, therefore, the general aim of the proposed studies herein to investigate the possibility that one of these factors involves an antagonistic interaction between alcohol and antihypertensive medication. This hypothesis is supported by recent findings from our laboratory showing that ethanol-induced hypertension in rats involves sympathetic overactivity. Furthermore, others and data of our own have shown that ethanol has a pressor effect in human hypertensives, attenuates baroreflexes and possesses an alpha blocking like activity. All these hemodynamic effects are in marked contrast with those evoked by some antihypertensive medications e.g. centrally acting drugs. The fact that the recent trend in treating hypertension involves the initial(mono) therapy regimen using these drugs, especially the newer ones guanabenz and clonidine, warrants investigating this important health related interaction. The first aim of this proposal is to investigate the hypothesis that acute ethanol administration reverses the hypotensive action of centrally acting antihypertensive drugs. The second aim is to test the hypothesis that concurrent chronic alcohol intake attenuates the therapeutic effect of clonidine and guanabenz. The third aim is to investigate the potential mechanism(s) responsible for this health-related interaction with emphasis being placed on the role of the sympathetic nervous system. The experiments proposed herein are intended to test these hypotheses in conscious spontaneously hypertensive and normotensive rats chronically instrumented for hemodynamic and electrophysiological measurements. These studies are expected to provide significant new insights about the effect of ethanol consumption on the responsiveness to antihypertensive therapy, the possible mechanism(s) by which this interaction occurs and whether this interaction is specific for centrally acting antihypertensive drugs.

Alcohol-induced cardiovascular anomalies have been demonstrated mainly in men and male experimental animals. Gender-related differences in cardiovascular function and reflexes make it unreasonable to extrapolate available findings in the male to the female population. Even in the latter, the hemodynamic effects of ethanol may vary between premenopausal and postmenopausal women and to be further confounded by the concurrent use of exogenous estrogen as a contraceptive or replacement therapy in the two populations, respectively. The proposed studies will focus on these issues. Renewed interest in estrogen as oral contraceptives in premenopausal women and as replacement therapy in postmenopausal women and the concurrent alcohol use by some of these women make the proposed studies noteworthy. In its recent formulations and dosage, estrogen given alone or in combination with progestins exert beneficial cardiovascular actions. Given the widespread use of alcohol, studies that deal with the action of ethanol on the cardiovascular function and reflexes of the female population and the type of interaction (beneficial or adverse) between ethanol and estrogen are warranted. The first aim is intended to support the hypothesis that the acute hemodynamic effects of ethanol are influenced by the menopausal state. Whether gender-related differences in the pharmacokinetics of ethanol and baroreflex activity influence the hemodynamic responses to ethanol will be investigated. The second aim tests the hypotheses: (i) *{the chronic cardiac and vascular effects of moderate alcohol use are influenced by menopausal state}*, and (ii) alcohol compromises the protective cardiac and vascular effects of estrogen replacement therapy which involve, at least in part, the endothelium-derived relaxing factor nitric oxide. The third aim *{ explores the possibility that the magnitude and time-course of the chronic blood pressure responses to moderate amounts of alcohol are influenced by the menopausal state. Moderate alcohol use increases circulating estrogen levels, by aromatizing adrenal androgens, in surgical menopause (ovariectomized women or rats). These alcohol-evoked hormonal changes are expected to influence its short and long term effects on blood pressure. The cardiovascular protective effects of estrogen and alcohol- evoked changes in estrogen levels in postmenopausal women have been replicated in female rats. Therefore, findings of the proposed studies are expected to yield clinically relevant information.}* The proposed studies are intended to test these hypotheses in unrestrained conscious rats chronically instrumented for hemodynamic, sympathetic neural activity, and blood ethanol and estrogen level measurements. *{The proposed study focuses on the hemodynamic effects of moderate amounts of alcohol in the ovariectomized rat; a model for surgical menopause. In addition to gaining basic knowledge about the effects of moderate alcohol use on the cardiovascular function of the female population, the studies are expected to yield relevant information on the hemodynamic effects of moderate alcohol use in postmenopausal women.}*

DESCRIPTION (provided by applicant): Alcohol elicits unique cardiovascular responses in the female population that are not only different from those seen in males but are also significantly influenced by the ovarian hormones, particularly estrogen. The objective of this proposal is to elucidate the molecular mechanisms implicated in the estrogen-dependent hemodynamic responses elicited by ethanol in female rats. Given the remarkable resemblance of the estrogen-dependent hemodynamic responses elicited by ethanol to the manifestations associated with mild endotoxicemia, we hypothesize that the NOS-NO signaling pathway plays a pivotal role in these responses. To test this hypothesis, we propose to conduct a series of integrative, signal transduction and gene expression studies under three aims. Aim 1 tests the hypothesis that activation of the vascular and/or cardiac nitric oxide synthases (NOS) mediates the estrogen-dependent hypotension and myocardial depression caused by acute alcohol in female rats. Since increased production of NO in the nucleus tractus solitarius (NTS) elicits hypotension, aim 2 studies will test the hypothesis that overproduction of NOS-derived NO in the NTS caused by additive or synergistic ethanol-estrogen interaction is implicated in the hypotensive and baroreflex depressant effects of acute ethanol in female rats. Aim 3 studies will identify the cellular mechanisms implicated in the chronic estrogen-dependent hypotensive and baroreflex depressant effects of ethanol in a model of surgical menopause. The proposal adopts a well-designed experimental approach that incorporates an established animal model, appropriate controls, and pharmacological interventions to: (i) establish a causal relationship between the up-regulation of NOS-derived NO in peripheral cells (myocyte and vascular smooth muscle) and neurons (NTS) and the estrogen-dependent cardiovascular effects of ethanol, and (ii) identify the molecular mechanisms implicated in the actions of ethanol, estrogen and their combination on NOS-NO signaling. The proposed research, whose primary focus is to probe the molecular mechanisms of estrogen-dependent hemodynamic effects of ethanol, addresses in a timely manner a significant biomedical problem and is expected to yield clinically relevant information.

[unreadable] DESCRIPTION (provided by applicant): Alcohol elicits unique cardiovascular responses, which are not only dependent on the neuronal substrates within the brainstem but also on the genetic state of these neurons. The objective of this proposal is to elucidate the molecular mechanisms implicated in the differential effect of ethanol on specialized neurons in the brainstem that control blood pressure and cardiac reflexes in a model of essential hypertension, the spontaneously hypertensive rat (SHR). Our recent intriguing findings showed that site dependent neurochemical (norepinephrine, NE) and IEG gene/protein expression (c-jun/c-Jun) responses elicited by ethanol in the ventrolateral medulla (RVLM) and nucleus tractus solitarius (NTS) determine its divergent effects on blood pressure and baroreflex responses in hypertensive and normotensive rats. Given the altered cardiovascular neurobiology and neuronal sensitivity to ethanol in SHRs, we hypothesize that heme oxygenase (HO) derived carbon monoxide (CO) constitutes a novel molecular mechanism for the centra! cardiovascular effects of ethanol. To test this hypothesis, we propose a series of integrative, and molecular studies under three aims. Aim 1 establishes brainstem HO-CO pathway as a molecular mechanism for the divergent cardiovascular actions of ethanol in SHRs and WKY rats. Aim 2 will elucidate the effect of ethanol on the association of HO with its regulatory proteins caveolin-1 and calmodulin in brainstem neurons of SHRs and WKY rats. Aim 3 characterizes the role of HO-CO-MAPK pathway in ethanol-mediated cardiovascular responses. Since catalase activity (the major enzyme that metabolizes ethanol in the brain) is altered in SHRs, the potential contribution of acetaldehyde to ethanol actions will be investigated. The proposal adopts a well designed experimental approach that incorporates an established model system, appropriate controls and pharmacological and siRNA interventions to: (i) establish a causal relationship between inhibition of HO-derived CO and the sympathoexcitatory (pressor) and baroreflex depressant effects of ethanol, and (ii) identify the molecular mechanisms implicated in the site- and strain-dependent neurochemical and cardiovascular effects of ethanol. The proposed research whose primary focus is to probe the molecular mechanisms implicated in the adverse ethanol effects on cardiovascular neurobiology, addresses a significant biomedical problem and is expected to yield clinically relevant information. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): 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.

Here, we seek to understand the role of central and cardiac circadian rhythm in the sex/estrogen (E2)-dependent vulnerability to alcohol-evoked cardiotoxicity. This overlooked translational research is timely because young women's alcohol consumption is rapidly increasing despite their higher sensitivity to the cardiotoxic effect of alcohol, compared to men. While limited (mostly generated in non-cardiovascular tissues) data support our scientific premise, there are no studies on whether E2-circardian rhythm interaction in the heart or autonomic nuclei regulates cardiac redox enzyme and function via heart specific miRNAs, particularly in the presence of alcohol. We hypothesize that ethanol disruption of the E2/estrogen receptor (ER) modulation of the circadian rhythm (PERIOD genes; Per1/Per2)-regulated redox enzymes paradoxically transforms E2 into a pro-inflammatory hormone. Specifically, we will elucidate the unresolved role of the ER?-Per2 dependent divergent upregulation of cardiac catalase and aldehyde dehydrogenase (ALDH2), and downregulation of hemeoxygenase (HO-1), in this female health related problem. We will focus on these cardiac enzymes, and heart-specific miRNAs that mediate protection or injury. Notably, catalase and ALDH2 regulate the cellular redox status and cell survival as well as oxidative metabolism of ethanol. To test our novel hypotheses, we assembled a capable research team to execute a multidimensional approach encompassing integrative cardiovascular, genetic, cellular and pharmacological studies. These studies will yield new insights into the role of the circadian rhythm in E2-dependent cardioprotection and ethanol-induced cardiotoxicity as well as identifying novel therapeutics for mitigating the chronic cardiovascular anomalies caused by alcohol in females. The two logically overlapping areas to be investigated in this project are: Aim 1 studies will test the hypothesis that disruption of the E2/ER?-Per2 loop regulation of redox enzymes and heart specific miRNAs mediate ethanol-evoked myocardial oxidative stress/dysfunction in females. Multilevel studies in rat models sensitive, or resistant, to ethanol-evoked myocardial dysfunction, and in genetic models (ER?/ ER?/GPER KO and Per2 loss of function, mPer2, mice) will generate robust data to test our hypothesis. Aim 2 studies will test the hypothesis that concomitant ethanol-evoked cardiac BH4 depletion/eNOS uncoupling and E2/Per2 divergent regulation of HO-1 and catalase trigger the death associated protein kinase-3 (DAPK-3) signaling cascade to cause myocardial oxidative stress/dysfunction. We will also identify cell signaling cascades as novel therapeutic targets for alleviating the E2/circadian rhythm-dependent cardiovascular derangements caused by chronic ethanol in females.