Effect of chronic ethanol ingestion and gender on heart left ventricular p53 gene expression

Smoking, alcohol and opioids effect on coronary microcirculation: an update overview

Smoking, heavy alcohol drinking and drug abuse are detrimental lifestyle factors leading to loss of million years of healthy life annually. One of the major health complications caused by these substances is the development of cardiovascular diseases (CVD), which accounts for a significant proportion of substance-induced death. Smoking and excessive alcohol consumption are related to the higher risk of acute myocardial infarction. Similarly, opioid addiction, as one of the most commonly used substances worldwide, is associated with cardiac events such as ischemia and myocardial infarction (MI). As supported by many studies, coronary artery disease (CAD) is considered as a major cause for substance-induced cardiac events. Nonetheless, over the last three decades, a growing body of evidence indicates that a significant proportion of substance-induced cardiac ischemia or MI cases, do not manifest any signs of CAD. In the absence of CAD, the coronary microvascular dysfunction is believed to be the main underlying reason for CVD. To date, comprehensive literature reviews have been published on the clinicopathology of CAD caused by smoking and opioids, as well as macrovascular pathological features of the alcoholic cardiomyopathy. However, to the best of our knowledge there is no review article about the impact of these substances on the coronary microvascular network. Therefore, the present review will focus on the current understanding of the pathophysiological alterations in the coronary microcirculation triggered by smoking, alcohol and opioids.

Alcohol effects on cardiac function

The consumption of ethanol can have both beneficial and detrimental effects on the function of the heart and cardiovascular system, depending on the amount consumed. Low-to-moderate amounts of ethanol intake are associated with improvements in cardiac function and vascular health. On the other hand, ethanol chronically consumed in large amounts acts as a toxin to the heart and vasculature. The cardiac injury produced by chronic alcohol abuse can progress to heart failure and eventual death. Furthermore, alcohol abuse may exacerbate preexisting heart conditions, such as hypertension and cardiomyopathy. This article focuses on the molecular mechanisms and pathophysiology of both the beneficial and detrimental cardiac effects of alcohol.

nNOS is involved in cardiac remodeling induced by chronic ethanol consumption

Chronic ethanol consumption has deleterious effects on the cardiovascular system by directly damaging the myocardial structure and/or by neurohormonal activation. Moreover, nitric oxide (NO) derived from neuronal NO synthase (nNOS) seems to be important to balance the harmful effects of ethanol consumption, because it influences several aspects of cardiac physiology and attenuates pathological cardiac remodeling. However, the impact of chronic ethanol consumption on nNOS expression is unknown. We address this subject in the present study by evaluating whether chronic ethanol consumption induces cardiac remodeling and hypertension, and if these changes are associated with alterations in the expression of nNOS. Male Wistar rats were examined after ingesting a 20% alcohol solution for 6 months. Blood alcohol concentration and brain natriuretic peptide (BNP) levels were measured. The cardiac remodeling was assessed by histomorphometric analysis and the nNOS expression was evaluated by immunofluorescence and western blot analysis. Our results show that chronic ethanol consumption induces cardiac remodeling, namely thinning of left ventricular wall, cardiomyocyte hypertrophy and increased fibrosis, and elevations of arterial blood pressure. They also show that in rats fed with ethanol for 6 months, the circulating BNP levels had decreased as well as the expression of nNOS in left ventricle cardiomyocytes. These findings suggest that the effects of chronic ethanol consumption on BNP levels and/or on nNOS expression in cardiomyocytes may contribute to aggravate the cardiac remodeling and leads to progression of cardiomyopathy.

Angiotensin II plays a critical role in alcohol-induced cardiac nitrative damage, cell death, remodeling, and cardiomyopathy in a protein kinase C/nicotinamide adenine dinucleotide phosphate oxidase-dependent manner

OBJECTIVES

The purpose of this study was to examine the cellular and molecular mechanisms underlying alcoholic cardiomyopathy.

BACKGROUND

The mechanism for alcoholic cardiomyopathy remains largely unknown.

METHODS

The chronic cardiac effects of alcohol were examined in mice feeding with alcohol or isocaloric control diet for 2 months. Signaling pathways of alcohol-induced cardiac cell death were examined in H9c2 cells.

RESULTS

Compared with controls, hearts from alcohol-fed mice exhibited increased apoptosis, along with significant nitrative damage, demonstrated by 3-nitrotyrosine abundance. Alcohol exposure to H9c2 cells induced apoptosis, accompanied by 3-nitrotyrosine accumulation and nicotinamide adenine dinucleotide phosphate oxidase (NOX) activation. Pre-incubation of H9c2 cells with urate (peroxynitrite scavenger), N(G)-nitro-L-arginine methyl ester (a nitric oxide synthase inhibitor), manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (a superoxide dismutase mimetic), and apocynin (NOX inhibitor) abrogated alcohol-induced apoptosis. Furthermore, alcohol exposure significantly increased the expression of angiotensin II and its type 1 receptor (AT1). A protein kinase C (PKC)-α/β1 inhibitor or PKC-β1 small interfering RNA and an AT1 blocker prevented alcohol-induced activation of NOX, and the AT1 blocker losartan significantly inhibited the expression of PKC-β1, indicating that alcohol-induced activation of NOX is mediated by PKC-β1 via AT1. To define the role of AT1-mediated PKC/NOX-derived superoxide generation in alcohol-induced cardiotoxicity, mice with knockout of the AT1 gene and wild-type mice were simultaneously treated with alcohol for 2 months. The knockout AT1 gene completely prevented cardiac nitrative damage, cell death, remodeling, and dysfunction. More importantly, pharmacological treatment of alcoholic mice with superoxide dismutase mimetic also significantly prevented cardiac nitrative damage, cell death, and remodeling.

CONCLUSIONS

Alcohol-induced nitrative stress and apoptosis, which are mediated by angiotensin II interaction with AT1 and subsequent activation of a PKC-β1-dependent NOX pathway, are a causal factor in the development of alcoholic cardiomyopathy.

Slow conduction and gap junction remodeling in murine ventricle after chronic alcohol ingestion

BACKGROUND

Long-term heavy alcohol drinkers are prone to the development of cardiac arrhythmia. To understand the mechanisms, we evaluated the cardiac structural and electrophysiological changes in mice chronically drinking excessive alcohol.

RESULTS

Male C57BL/6J mice were given 36% alcohol in the drinking water. Those given blank water were used as control. Twelve weeks later, the phenotypic characteristics of the heart, including gap junctions and electrical properties were examined. In the alcohol group the ventricles contained a smaller size of cardiomyocytes and a higher density of capillary networks, compared to the control. Western blots showed that, after drinking alcohol, the content of connexin43 (Cx43) protein in the left ventricle was increased by 18% (p < 0.05). Consistently, immunoconfocal microscopy demonstrated that Cx43 gap junctions were up-regulated in the alcohol group with a disorganized distribution, compared to the control. Optical mapping showed that the alcohol group had a reduced conduction velocity (40 ± 18 vs 60 ± 7 cm/sec, p < 0.05) and a higher incidence of ventricular tachyarrhythmia (62% vs 30%, p < 0.05).

CONCLUSION

Long-term excessive alcohol intake resulted in extensive cardiac remodeling, including changes in expression and distribution of gap junctions, growth of capillary network, reduction of cardiomyocyte size, and decrease of myocardial conduction.

Effects of ethanol on mouse embryonic stem cells

BACKGROUND

Fetal alcohol syndrome (FAS) reflects a constellation of congenital abnormalities caused by excess maternal consumption of alcohol. It is likely that interference with embryonic development plays a role in the pathogenesis of the disorder. Ethanol-induced apoptosis has been suggested as a causal factor in the genesis of FAS. Mouse embryonic stem (mES) cells are pluripotent cells that differentiate in vitro to cell aggregates termed embryoid bodies (EBs), wherein differentiation capacity and gene expression profile are similar to those of the early embryo.

METHODS

To investigate the effects of ethanol during differentiation, mES cells were cultured on a gelatin surface in the presence of leukemia inhibitory factor which maintains adherent undifferentiated cells or in suspension to promote formation of EBs. All cells were treated (1-6 days) with 80 mM ethanol. The pluripotency and differentiation of mES cells were evaluated by western blotting of stage-specific embryonic antigen (SSEA-1), transcription factors Oct-3/4, Sox-2, and Nanog, using alkaline phosphatase staining. Apoptosis (early to late stages) was assessed by fluorescence-activated cell sorting using TdT-mediated biotin-dUTP nick-end labelling assay and fluorescein isothiocyanate-Annexin V/propidium iodide staining.

RESULTS

Ethanol increased apoptosis during in vitro differentiation of mES cells to EBs, whereas undifferentiated cells were not affected. Ethanol exposure also interfered with pluripotency marker patterns causing an upregulation of SSEA-1 under self-renewal conditions. In EBs, ethanol delayed the downregulation of SSEA-1 and affected the regulation of transcription factors during differentiation.

CONCLUSION

Our findings suggest that ethanol may contribute to the pathogenesis of FAS by triggering apoptotic pathways during differentiation of embryonic stem cells and deregulating early stages of embryogenesis.

Ethanol impairs estrogen receptor signaling resulting in accelerated activation of senescence pathways, whereas estradiol attenuates the effects of ethanol in osteoblasts

Epidemiological and animal studies have suggested that chronic alcohol consumption is a major risk factor for osteoporosis. Using bone from cycling female rats infused chronically with ethanol (EtOH) in vivo and osteoblastic cells in vitro, we found that EtOH significantly increased estrogen receptor alpha (ERalpha) and beta (ERbeta) mRNA and ERalpha protein levels. Treatment with 17beta-estradiol (E2) in vivo and in vitro interfered with these effects of EtOH on bone and osteoblastic cells. ERalpha agonist propylpyrazoletriol (PPT) and ERbeta agonist diarylpropionitrile (DPN) attenuated EtOH-induced ERalpha and ERbeta gene overexpression, respectively. Similar to the ER antagonist ICI 182780, EtOH blocked nuclear translocation of ERalpha-ECFP in the presence of E2 in UMR-106 osteoblastic cells. EtOH also downregulated ERE-luc reporter activity. On the other hand, EtOH by itself upregulated some common ERalpha- and ERbeta-mediated genes apparently by an ER-independent pathway. EtOH also transactivated the luciferase activity of the p21 promoter region independent of additional exogenous ERalpha, activated p21 and p53, and stimulated senescence-associated beta-galactosidase activity in rat stromal osteoblasts. E2 treatment attenuated these EtOH actions. We conclude that inhibitory cross-talk between EtOH and E2 in osteoblasts on ERs, p53/p21, and cell senescence provides a pathophysiologic mechanism underlying bone loss and the protective effects of estrogens in alcohol-exposed females.

Expression of renin-angiotensin system and peroxisome proliferator-activated receptors in alcoholic cardiomyopathy

BACKGROUND

Alcoholic cardiomyopathy (ACM) develops in response to chronic alcohol intake and it is hypothesized that activation of the renin-angiotensin system (RAS) and disorders in energy metabolism may play important roles in its onset. Given that the expression of peroxisome proliferator-activated receptors (PPARalpha and PPARgamma) changes with alterations in cardiac metabolism and myocardial remodeling, this study was designed to test the hypothesis that protein expression of PPARalpha and PPARgamma is correlated with RAS activation in ACM.

METHODS

For the first experiment, rats were divided into 3 groups: 30 received alcohol (intragastric administration with ad libitum drinking), 30 received alcohol and irbesartan (5 mg/kg/d, p.o.), and 30 served as controls. RAS activity and protein expression of PPARalpha and PPARgamma were evaluated in rats following 6 months of alcohol feeding using radioimmunoassay, reverse transcriptase PCR, and Western blot methods. For the second experiment, rats were divided into 4 groups: 10 rats received alcohol/irbesartan (5 mg/kg/d, p.o.)/PD98059 (methyl ethyl ketone [MEK]-1 inhibitor) (0.3 mg/kg/d, p.o.), 10 rats received alcohol/PD98059, 10 rats received alcohol/irbesartan, and 10 rats received alcohol alone. Myocardial PPARalpha and PPARgamma protein expression was detected following 6 months of alcohol feeding using Western blot method.

RESULTS

Compared with controls, myocardial angiotensin (Ang) I, Ang II, and renin levels were progressively increased at 2, 4, and 6 months of alcohol intake. mRNA expression of renin, angiotensinogen, angiotensin-converting enzyme (ACE), and AT1 was increased at 6 months. Moreover, activated RAS downregulated PPARalpha and upregulated PPARgamma protein expression as ACM progressed. Finally, extracellular signal regulated kinase 1 and 2 (ERK1/2) was shown to play a key role in the regulation of protein expression of PPARalpha and PPARgamma.

CONCLUSION

These results suggest that RAS is activated during the development of ACM. Moreover, ERK1/2 plays a key role in the regulation of protein expression of PPARalpha and PPARgamma by RAS in ACM.

Rodent models of heart failure

Heart failure, a complex disorder with heterogeneous aetiologies remains one of the most threatening diseases known. It is a clinical syndrome attributable to a multitude of factors that begins with the compensatory response known as hypertrophy, followed by a decompensated state that finally results in heart failure. Given the lack of a unified theory of heart failure, future research efforts are required to unify and synthesize our current understanding of the multiple mechanisms that control remodelling in heart under various stress conditions. During the past few decades, use of animal models has provided new insights into the complex pathogenesis of this syndrome. Rodents have contributed significantly in the understanding of the pathogenesis and progression of heart failure. With the advent of the transgenic era, rodent models have revolutionized preclinical research associated with heart failure. These models combined with physiological measurements of cardiac hemodynamics, are expected to yield more valuable information regarding the molecular mechanisms of heart failure and aid in the discovery of novel therapeutic targets. However, all animal models used have advantages and limitations, and the issues determining transfer from preclinical to clinical require critical evaluation. The present review focuses upon rodent models of heart failure.