Involvement of free radical mechanism in the toxic effects of alcohol: implications for fetal alcohol syndrome

Transgenerational of Oxidative Damage Induced by Prenatal Ethanol Exposure on Spatial Learning/Memory and BDNF in the of Male Rats

Alcohol consumption during pregnancy harms fetal development, leading to various physical and behavioral issues. This study investigates how prenatal ethanol exposure triggers oxidative stress (OS) and affects neurotrophic factors (NTFs), particularly brain-derived growth factor (BDNF) gene expression in the hippocampus, influencing learning and memory decline across two generations of male offspring from ethanol-exposed female rats. A rat model of fetal alcohol spectrum disorder (FASD) was initially generated to reflect on the deficits in the first generation, and then those transmitted via the male germline to the unexposed male ones. The pregnant rats were thus divided into four groups, namely, the control group (CTRL) receiving only distilled water (DW), and three groups being exposed to ethanol (20 %, 4.5 g/kg) by oral gavage, during the first 10-day gestation (FG), the second 10-day gestation (SG), and the entire gestation (EG) periods. Subsequent Morris water maze (MWM) tests on male offspring revealed spatial learning deficits during the second and entire gestational periods in both generations. Analysis of antioxidant enzyme activity including glutathione peroxidase (GPx), superoxide dismutase (SOD), and malondialdehyde (MDA), and BDNF gene expression in the hippocampus further highlighted the impacts of prenatal ethanol exposure. The study results demonstrated that prenatal ethanol exposure caused spatial learning/memory deficits during the SG and EG, altered antioxidant enzyme activity, and reduced BDNF gene expression in both generations. The findings underscore the role of OS in developmental and behavioral issues in FASD rat models and suggest that lasting transgenerational effects in the second generation may stem from alcohol-induced changes.

Fetal alcohol and maternal stress modify the expression of proteins controlling postnatal development of the male rat hippocampus

Background: Developing brains can partially get over prenatal alcohol exposure-related detrimental conditions by activating some mechanisms involved in survival. Objectives: This study aimed to shed light on the molecular correlates of compensatory mechanisms by examining temporal profiles in the expression of proteins controlling postnatal development in the rat hippocampus prenatally exposed to intubation stress/ethanol. Methods: Male pups were randomly assigned to age subgroups (n = 21/age) which were sacrificed on postnatal day (PD)1, PD10, PD30, and PD60. Ethanol (6 g/kg/day) were intragastrically intubated to the dams throughout 7-21 gestation days. The expression of neurogenesis and angiogenesis markers, extracellular matrix proteins, and growth-promoting ligands were examined by western blot. Results: The most rapid increase in the index of neuronal maturation was noted between PD10-PD30 (p < .05). Prenatal stress caused a decrease of neurogenesis markers at birth and an increase of their expressions at PD10 and PD30 to reach control levels (p < .001). The impact of fetal-alcohol was observed as a decrease in the expression of synaptic plasticity protein versican at birth (p < .001), an increase in the synaptic repulsion protein ephrin-B2 at PD10 (p < .001), and a decrease in the maturation of BDNF at PD30 (p < .001) with a decrease in the mature neuron markers at PD30 (p < .001) and PD60 (p = .005) which were compensated with upregulation of angiogenesis and increasing brevican expression, a neuronal maturation protein (p < .001). Conclusion: These data provide in vivo evidence for the potential therapeutic factors related to neurogenesis, angiogenesis, and neurite remodeling which may tolerate the alcohol/stress dependent teratogenicity in the developing hippocampus.

Family Environment, Neurodevelopmental Risk, and the Environmental Influences on Child Health Outcomes (ECHO) Initiative: Looking Back and Moving Forward

The family environment, with all its complexity and diverse components, plays a critical role in shaping neurodevelopmental outcomes in children. Herein we review several domains of the family environment (family socioeconomic status, family composition and home environment, parenting behaviors and interaction styles, parental mental health and functioning, and parental substance use) and discuss how these domains influence neurodevelopment, with particular emphasis on mental health outcomes. We also highlight a new initiative launched by the National Institutes of Health, the Environmental influences on Child Health Outcomes (ECHO) program. We discuss the role that ECHO will play in advancing our understanding of the impact of the family environment on children's risk for psychiatric outcomes. Lastly, we conclude with important unanswered questions and controversies in this area of research, highlighting how ECHO will contribute to resolving these gaps in our understanding, clarifying relationships between the family environment and children's mental health.

Feeding Vitamin C during Neonatal and Juvenile Growth Improves Learning and Memory of Rats

We investigated the effects of feeding vitamin C (Vit C) during neonatal and juvenile growth on learning and memory of rats. Rats after delivery were randomly divided into four groups and treated. Group 1, control group, received normal drinking water. Groups 2-4 received Vit C 10, 100, and 500 mg/kg, respectively, from the first day. After 8 weeks, 10 male offspring of each group were randomly selected and tested in the Morris water maze (MWM) and passive avoidance (PA) tests. Finally, the brains were removed for biochemical measurement. In MWM, 10-500 mg/kg Vit C reduced the latency and traveled distance and increased time spent in the target quadrant. In PA, 10 and 100 mg/kg of Vit C increased the latency; 10-500 mg/kg of Vit C decreased the malondialdehyde (MDA) in the brain tissues and increased thiol and catalase (CAT) activity compared to the control group. We showed that feeding rats Vit C during neonatal and juvenile growth has positive effects on learning and memory.

Binge ethanol exposure induces endoplasmic reticulum stress in the brain of adult mice

Alcohol abuse causes brain damage and cognitive dysfunction. However, the underlying mechanisms remain elusive. Endoplasmic reticulum (ER) acts as machinery to ensure the proper folding of newly synthesized proteins. The perturbation of ER, i.e., ER stress, plays a pivotal role in some neurological disorders. Mammalian target of rapamycin (mTOR), a serine/threonine kinase, is involved in the regulation of ER stress. The current study sought to determine whether binge ethanol exposure induces ER stress in adult mouse brain and the role mTOR signaling during this process. Adult C57BL6 mice received binge ethanol exposure by daily gavage (5 g/kg, 25% ethanol w/v) for 1, 5 or 10 days. Binge ethanol exposure caused neurodegeneration and neuroinflammation after 5 days of exposure, and a concomitant increase of ER stress and inhibition of mTOR. However, ethanol exposure did not significantly alter spatial learning and memory, and spontaneous locomotor activity. Ethanol treatment induced ER stress and the death of cultured neuronal cells. Cotreatment with an ER stress inhibitor, sodium 4-phenylbutyrate (4-PBA) significantly diminished ethanol-induced ER stress and neuronal apoptosis, suggesting that ER stress contributes to ethanol-induced neurodegeneration. Furthermore, the blockage of mTOR activity by rapamycin increased ER stress in cultured neuronal cells; whereas the activation or inhibition of ER stress by tunicamycin or 4-PBA respectively had little effects on mTOR signaling. These results suggested that mTOR signaling is upstream of ER stress and may thereby mediate ethanol-induced ER stress.

Alcohol Teratogenesis: Mechanisms of Damage and Strategies for Intervention

There are multiple mechanisms by which alcohol can damage the developing brain, but the type of damage induced will depend on the amount and developmental timing of exposure, along with other maternal and genetic factors. This article reviews current perspectives on how ethanol can produce neuroteratogenic effects by its interactions with molecular regulators of brain development. The current evidence suggests that alcohol produces many of its damaging effects by exerting specific actions on molecules that regulate key developmental processes (e.g., L1 cell adhesion molecule, alcohol dehydrogenase, catalase), interfering with the early development of midline serotonergic neurons and disrupting their regulatory-signaling function for other target brain structures, interfering with trophic factors that regulate neurogenesis and cell survival, or inducing excessive cell death via oxidative stress or activation of caspase-3 proteases. The current understanding of pathogenesis mechanisms suggests several strategic approaches to develop rational molecular prevention. However, the development of behavioral and biologic treatments for alcohol-affected children is crucial because it is unlikely that effective delivery of preventative interventions can realistically be achieved in ways to prevent prenatal damage in at-risk pregnancies. Toward that end, behavioral training that promotes experience-dependent neuroplasticity has been effective in a rat model of cerebellar damage induced by alcohol exposure during the period of brain development that is comparable to that of the human third trimester.

NOX2 amplifies acetaldehyde-mediated cardiomyocyte mitochondrial dysfunction in alcoholic cardiomyopathy

Alcoholic cardiomyopathy (ACM) resulting from excess alcohol consumption is an important cause of heart failure (HF). Although it is assumed that the cardiotoxicity of the ethanol (EtOH)-metabolite acetaldehyde (ACA) is central for its development and progression, the exact mechanisms remain obscure. Murine cardiomyocytes (CMs) exposed to ACA or EtOH showed increased superoxide (O₂^•−) levels and decreased mitochondrial polarization, both being normalized by NADPH oxidase (NOX) inhibition. C57BL/6 mice and mice deficient for the ACA-degrading enzyme mitochondrial aldehyde dehydrogenase (ALDH-2^−/−) were fed a 2% EtOH diet for 5 weeks creating an ACA-overload. 2% EtOH-fed ALDH-2^−/− mice exhibited a decreased cardiac function, increased heart-to-body and lung-to-body weight ratios, increased cardiac levels of the lipid peroxidation product malondialdehyde (MDA) as well as increased NOX activity and NOX2/glycoprotein 91^phox (NOX2/gp91^phox) subunit expression compared to 2% EtOH-fed C57BL/6 mice. Echocardiography revealed that ALDH-2^−/−/gp91^phox−/− mice were protected from ACA-overload-induced HF after 5 weeks of 2% EtOH-diet, demonstrating that NOX2-derived O₂^•− contributes to the development of ACM. Translated to human pathophysiology, we found increased gp91^phox expression in endomyocardial biopsies of ACM patients. In conclusion, ACM is promoted by ACA-driven mitochondrial dysfunction and can be improved by ablation of NOX2/gp91^phox. NOX2/gp91^phox therefore might be a potential pharmacological target to treat ACM.

An Update on Fetal Alcohol Syndrome-Pathogenesis, Risks, and Treatment

Alcohol is a well-established teratogen that can cause variable physical and behavioral effects on the fetus. The most severe condition in this spectrum of diseases is known as fetal alcohol syndrome (FAS). The differences in maternal and fetal enzymes, in terms of abundance and efficiency, in addition to reduced elimination, allow for alcohol to have a prolonged effect on the fetus. This can act as a teratogen through numerous methods including reactive oxygen species (generated as by products of CYP2E1), decreased endogenous antioxidant levels, mitochondrial damage, lipid peroxidation, disrupted neuronal cell-cell adhesion, placental vasoconstriction, and inhibition of cofactors required for fetal growth and development. More recently, alcohol has also been shown to have epigenetic effects. Increased fetal exposure to alcohol and sustained alcohol intake during any trimester of pregnancy is associated with an increased risk of FAS. Other risk factors include genetic influences, maternal characteristics, for example, lower socioeconomic statuses and smoking, and paternal chronic alcohol use. The treatment options for FAS have recently started to be explored although none are currently approved clinically. These include prenatal antioxidant administration food supplements, folic acid, choline, neuroactive peptides, and neurotrophic growth factors. Tackling the wider impacts of FAS, such as comorbidities, and the family system have been shown to improve the quality of life of FAS patients. This review aimed to focus on the pathogenesis, especially mechanisms of alcohol teratogenicity, and risks of developing FAS. Recent developments in potential management strategies, including prenatal interventions, are discussed.

Mechanisms of neuroimmune gene induction in alcoholism

RATIONALE

Alcoholism is a primary, chronic relapsing disease of brain reward, motivation, memory, and related circuitry. It is characterized by an individual's continued drinking despite negative consequences related to alcohol use, which is exemplified by alcohol use leading to clinically significant impairment or distress. Chronic alcohol consumption increases the expression of innate immune signaling molecules (ISMs) in the brain that alter cognitive processes and promote alcohol drinking.

OBJECTIVES

Unraveling the mechanisms of alcohol-induced neuroimmune gene induction is complicated by positive loops of multiple cytokines and other signaling molecules that converge on nuclear factor kappa-light-chain-enhancer of activated B cells and activator protein-1 leading to induction of additional neuroimmune signaling molecules that amplify and expand the expression of ISMs.

RESULTS

Studies from our laboratory employing reverse transcription polymerase chain reaction (RT-PCR) to assess mRNA, immunohistochemistry and Western blot analysis to assess protein expression, and others suggest that ethanol increases brain neuroimmune gene and protein expression through two distinct mechanisms involving (1) systemic induction of innate immune molecules that are transported from blood to the brain and (2) the direct release of high-mobility group box 1 (HMGB1) from neurons in the brain. Released HMGB1 signals through multiple receptors, particularly Toll-like receptor (TLR) 4, that potentiate cytokine receptor responses leading to a hyperexcitable state that disrupts neuronal networks and increases excitotoxic neuronal death. Innate immune gene activation in brain is persistent, consistent with the chronic relapsing disease that is alcoholism. Expression of HMGB1, TLRs, and other ISMs is increased several-fold in the human orbital frontal cortex, and expression of these molecules is highly correlated with each other as well as lifetime alcohol consumption and age of drinking onset.

CONCLUSIONS

The persistent and cumulative nature of alcohol on HMGB1 and TLR gene induction support their involvement in alcohol-induced long-term changes in brain function and neurodegeneration.

Effects of pre-natal alcohol exposure on hippocampal synaptic plasticity: Sex, age and methodological considerations

The consumption of alcohol during gestation is detrimental to the developing central nervous system (CNS). The severity of structural and functional brain alterations associated with alcohol intake depends on many factors including the timing and duration of alcohol consumption. The hippocampal formation, a brain region implicated in learning and memory, is highly susceptible to the effects of developmental alcohol exposure. Some of the observed effects of alcohol on learning and memory may be due to changes at the synaptic level, as this teratogen has been repeatedly shown to interfere with hippocampal synaptic plasticity. At the molecular level alcohol interferes with receptor proteins and can disrupt hormones that are important for neuronal signaling and synaptic plasticity. In this review we examine the consequences of prenatal and early postnatal alcohol exposure on hippocampal synaptic plasticity and highlight the numerous factors that can modulate the effects of alcohol. We also discuss some potential mechanisms responsible for these changes as well as emerging therapeutic avenues that are beginning to be explored.

Fetal Alcohol Spectrum Disorder: Potential Role of Endocannabinoids Signaling

One of the unique features of prenatal alcohol exposure in humans is impaired cognitive and behavioral function resulting from damage to the central nervous system (CNS), which leads to a spectrum of impairments referred to as fetal alcohol spectrum disorder (FASD). Human FASD phenotypes can be reproduced in the rodent CNS following prenatal ethanol exposure. Several mechanisms are expected to contribute to the detrimental effects of prenatal alcohol exposure on the developing fetus, particularly in the developing CNS. These mechanisms may act simultaneously or consecutively and differ among a variety of cell types at specific developmental stages in particular brain regions. Studies have identified numerous potential mechanisms through which alcohol can act on the fetus. Among these mechanisms are increased oxidative stress, mitochondrial damage, interference with the activity of growth factors, glia cells, cell adhesion molecules, gene expression during CNS development and impaired function of signaling molecules involved in neuronal communication and circuit formation. These alcohol-induced deficits result in long-lasting abnormalities in neuronal plasticity and learning and memory and can explain many of the neurobehavioral abnormalities found in FASD. In this review, the author discusses the mechanisms that are associated with FASD and provides a current status on the endocannabinoid system in the development of FASD.

Role of microglia in regulation of ethanol neurotoxic action

Exposure to alcohol, during development or adulthood, may result in damage to the nervous system, which underlies neurological and cognitive disruptions observed in patients with alcohol-related disorders, including fetal alcohol spectrum disorders (FASDs) and alcohol-use disorders (AUDs). Both clinical and preclinical evidence suggest microglia, the immune cells of the central nervous system, play a key role in modulating alcohol-induced neurotoxicity. Particularly, microglia are implicated in alcohol-induced neuroinflammation and in alcohol-induced increases in oxidative stress, which can lead to neuronal apoptosis. Recent studies also suggest a regenerative role for microglia in reestablishing homeostasis after alcohol exposure. These studies are summarized and reviewed in this chapter with emphasis on relevance to FASD and AUD.

Network pharmacology-based antioxidant effect study of zhi-zi-da-huang decoction for alcoholic liver disease

Zhi-Zi-Da-Huang decoction (ZZDHD), a classic traditional Chinese medicine (TCM) formula, has been used for centuries to treat alcoholic liver disease. Reliable therapeutics of ZZDHD has also been validated in clinical practice. In this study, molecular docking and network analysis were carried out to explore the antioxidative mechanism of ZZDHD as an effective therapeutic approach to treat alcoholic liver disease. Multiple active compounds of ZZDHD were screened based on four key original enzymes (cytochrome P450 2E1, xanthine oxidase, inducible nitric oxide synthase, and cyclooxygenase-2) involved in ethanol-induced oxidative stress damage. A drug-target network was constructed through network pharmacology analysis, which predicted the relationships of active ingredients to the targets. Some results had been verified by the previous experimental pharmacological studies; meanwhile, it was first reported that xanthine oxidase and eriocitrin, neoeriocitrin, isorhoifolin, and poncirin had interactions. The network pharmacology strategy used provided a forceful tool for searching the mechanism of action of TCM formula and novel bioactive ingredients.

Feeding of Nigella sativa during neonatal and juvenile growth improves learning and memory of rats

The positive roles of antioxidants on brain development and learning and memory have been suggested. Nigella sativa (NS) has been suggested to have antioxidant and neuroprotective effects. This study was done to investigate the effects of feeding by the hydro-alcoholic extract of NS during neonatal and juvenile growth on learning and memory of rats. The pregnant rats were kept in separate cages. After delivery, they were randomly divided into four Groups including: (1) control; (2) NS 100 mg/kg (NS 100); (3) NS 200 mg/kg (NS 200); and (4) NS 400 mg/kg (NS 400). Rats in the control group (Group 1) received normal drinking water, whereas Groups 2, 3, and 4 received the same drinking water supplemented with the hydro-alcoholic extract of NS (100 mg/kg, 200 mg/kg, and 400 mg/kg, respectively) from the 1st day after birth through the first 8 weeks of life. After 8 weeks, 10 male offspring from each group were randomly selected and tested in the Morris water maze (MWM) and passive avoidance (PA) test. Finally, the brains were removed and total thiol groups and malondialdehyde (MDA) concentrations were determined. In the MWM, treatment by 400 mg/kg extract reduced both the time latency and the distance traveled to reach the platform compared to the control group (p < 0.05–p < 0.01). Both 200 mg/kg and 400 mg/kg of the extract increased the time spent in the target quadrant (p < 0.05–p < 0.01). In the PA test, the treatment of the animals by 200 mg/kg and 400 mg/kg of NS extract significantly increased the time latency for entering the dark compartment (p < 0.05–p < 0.001). Pretreatment of the animals with 400 mg/kg of NS extract decreased the MDA concentration in hippocampal tissues whereas it increased the thiol content compared to the control group (p < 0.001). These results allow us to propose that feeding of the rats by the hydro-alcoholic extract of NS during neonatal and juvenile growth has positive effects on learning and memory. The effects might be due to the antioxidant effects.

Ethanol exposure alters protein expression in a mouse model of fetal alcohol spectrum disorders

Alcohol exposure during development can result in variable growth retardation and facial dysmorphology known as fetal alcohol spectrum disorders. Although the mechanisms underlying the disorder are not fully understood, recent progress has been made that alcohol induces aberrant changes in gene expression and in the epigenome of embryos. To inform the gene and epigenetic changes in alcohol-induced teratology, we used whole-embryo culture to identify the alcohol-signature protein profile of neurulating C6 mice. Alcohol-treated and control cultures were homogenized, isoelectrically focused, and loaded for 2D gel electrophoresis. Stained gels were cross matched with analytical software. We identified 40 differentially expressed protein spots (P < 0.01), and 9 spots were selected for LC/MS-MS identification. Misregulated proteins include serotransferrin, triosephosphate isomerase and ubiquitin-conjugating enzyme E2 N. Misregulation of serotransferrin and triosephosphate isomerase was confirmed with immunologic analysis. Alteration of proteins with roles in cellular function, cell cycle, and the ubiquitin-proteasome pathway was induced by alcohol. Several misregulated proteins interact with effectors of the NF-κB and Myc transcription factor cascades. Using a whole-embryo culture, we have identified misregulated proteins known to be involved in nervous system development and function.

In vitro and in vivo studies on the antioxidant activity of fish peptide isolated from the croaker (Otolithes ruber) muscle protein hydrolysate

Peptide from croaker (Otolithes ruber) muscle protein hydrolysate was purified, characterized and evaluated for its in vitro and in vivo antioxidant activity. Results showed that purified peptide contained the amino acid sequence as Lys-Thr-Phe-Cys-Gly-Arg-His (861.6Da), which were expected to contribute to its antioxidant activities. This peptide efficiently quenched 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals (84.5±1.2 and 62.4±2.9%), and successfully inhibits the lipid peroxidation and DNA damage and proven to be a potent antioxidant at different in vitro systems. It also improved the endogenous cellular antioxidant enzymes in Wistar rat by increasing the activities of catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD) after supplementation of the peptide (283.6±7.25, 4.3±0.78 and 28.42±1.97) compared to the negative control (196.4±5.65, 1.3±0.45 and 15.1±0.35). Therefore, croaker muscle peptide can increase an endurance capacity and facilitate recovery from oxidative stress.

Molecular and behavioral aspects of the actions of alcohol on the adult and developing brain

The brain is one of the major target organs of alcohol actions. Alcohol abuse can lead to alterations in brain structure and functions and, in some cases, to neurodegeneration. Cognitive deficits and alcohol dependence are highly damaging consequences of alcohol abuse. Clinical and experimental studies have demonstrated that the developing brain is particularly vulnerable to alcohol, and that drinking during gestation can lead to a range of physical, learning and behavioral defects (fetal alcohol spectrum disorders), with the most dramatic presentation corresponding to fetal alcohol syndrome. Recent findings also indicate that adolescence is a stage of brain maturation and that heavy drinking at this stage can have a negative impact on brain structure and functions causing important short- and long-term cognitive and behavioral consequences. The effects of alcohol on the brain are not uniform; some brain areas or cell populations are more vulnerable than others. The prefrontal cortex, the hippocampus, the cerebellum, the white matter and glial cells are particularly susceptible to the effects of ethanol. The molecular actions of alcohol on the brain are complex and involve numerous mechanisms and signaling pathways. Some of the mechanisms involved are common for the adult brain and for the developing brain, while others depend on the developmental stage. During brain ontogeny, alcohol causes irreversible alterations to the brain structure. It also impairs several molecular, neurochemical and cellular events taking place during normal brain development, including alterations in both gene expression regulation and the molecules involved in cell-cell interactions, interference with the mitogenic and growth factor response, enhancement of free radical formation and derangements of glial cell functions. However, in both adult and adolescent brains, alcohol damages specific brain areas through mechanisms involving excitotoxicity, free radical formation and neuroinflammatory damage resulting from activation of the innate immune system mediated by TLR4 receptors. Alcohol also acts on specific membrane proteins, such as neurotransmitter receptors (e.g. NMDA, GABA-A), ion channels (e.g. L-type Ca²⁺ channels, GIRKs), and signaling pathways (e.g. PKA and PKC signaling). These effects might underlie the wide variety of behavioral effects induced by ethanol drinking. The neuroadaptive changes affecting neurotransmission systems which are more sensitive to the acute effects of alcohol occur after long-term alcohol consumption. Alcohol-induced maladaptations in the dopaminergic mesolimbic system, abnormal plastic changes in the reward-related brain areas and genetic and epigenetic factors may all contribute to alcohol reinforcement and alcohol addiction. This manuscript reviews the mechanisms by which ethanol impacts the adult and the developing brain, and causes both neural impairments and cognitive and behavioral dysfunctions. The identification and the understanding of the cellular and molecular mechanisms involved in ethanol toxicity might contribute to the development of treatments and/or therapeutic agents that could reduce or eliminate the deleterious effects of alcohol on the brain.

Alcohol and acetaldehyde in public health: from marvel to menace

Alcohol abuse is a serious medical and social problem. Although light to moderate alcohol consumption is beneficial to cardiovascular health, heavy drinking often results in organ damage and social problems. In addition, genetic susceptibility to the effect of alcohol on cancer and coronary heart disease differs across the population. A number of mechanisms including direct the toxicity of ethanol, its metabolites [e.g., acetaldehyde and fatty acid ethyl esters (FAEEs)] and oxidative stress may mediate alcoholic complications. Acetaldehyde, the primary metabolic product of ethanol, is an important candidate toxin in developing alcoholic diseases. Meanwhile, free radicals produced during ethanol metabolism and FAEEs are also important triggers for alcoholic damages.

Alcohol dehydrogenase accentuates ethanol-induced myocardial dysfunction and mitochondrial damage in mice: role of mitochondrial death pathway

Objectives

Binge drinking and alcohol toxicity are often associated with myocardial dysfunction possibly due to accumulation of the ethanol metabolite acetaldehyde although the underlying mechanism is unknown. This study was designed to examine the impact of accelerated ethanol metabolism on myocardial contractility, mitochondrial function and apoptosis using a murine model of cardiac-specific overexpression of alcohol dehydrogenase (ADH).

Methods

ADH and wild-type FVB mice were acutely challenged with ethanol (3 g/kg/d, i.p.) for 3 days. Myocardial contractility, mitochondrial damage and apoptosis (death receptor and mitochondrial pathways) were examined.

Results

Ethanol led to reduced cardiac contractility, enlarged cardiomyocyte, mitochondrial damage and apoptosis, the effects of which were exaggerated by ADH transgene. In particular, ADH exacerbated mitochondrial dysfunction manifested as decreased mitochondrial membrane potential and accumulation of mitochondrial O₂^•−. Myocardium from ethanol-treated mice displayed enhanced Bax, Caspase-3 and decreased Bcl-2 expression, the effect of which with the exception of Caspase-3 was augmented by ADH. ADH accentuated ethanol-induced increase in the mitochondrial death domain components pro-caspase-9 and cytochrome C in the cytoplasm. Neither ethanol nor ADH affected the expression of ANP, total pro-caspase-9, cytosolic and total pro-caspase-8, TNF-α, Fas receptor, Fas L and cytosolic AIF.

Conclusions

Taken together, these data suggest that enhanced acetaldehyde production through ADH overexpression following acute ethanol exposure exacerbated ethanol-induced myocardial contractile dysfunction, cardiomyocyte enlargement, mitochondrial damage and apoptosis, indicating a pivotal role of ADH in ethanol-induced cardiac dysfunction possibly through mitochondrial death pathway of apoptosis.

Thymosin-beta4 attenuates ethanol-induced neurotoxicity in cultured cerebral cortical astrocytes by inhibiting apoptosis

Thymosin-beta4 (Tbeta4) is a major actin monomer-binding peptide in mammalian tissues and plays a crucial role in the nervous system in synaptogenesis, neuronal survival and migration, axonal growth, and plastic changes of dendritic spines. However, it is unknown whether Tbeta4 is also involved in challenges with external stress such as ethanol-induced neurotoxicity. In the present study, we investigated the effects of Tbeta4 on ethanol-induced neurotoxicity in cultured cerebral cortical astrocytes and the underlying mechanisms. Primarily cultured astrocytes were treated with 1 microg/ml Tbeta4 2 h prior to administration of 100 mM ethanol for 0.5, 1, 3 and 6 days, respectively. The results showed that ethanol caused neurotoxicity in cultured astrocytes, as shown by declined cell viability, distinct astroglial apoptosis and increased intracellular peroxidation. Tbeta4 markedly promoted cell viability, ameliorated the injury of intracellular glial fibrillary acidic protein-immunopositive cytoskeletal structures, reduced the percentage of apoptotic astrocyte and cellular DNA fragmentation, suppressed caspase-3 activity and upregulated Bcl-2 expression, inhibited the accumulation of reactive oxygen species and production of malondialdehyde in ethanol-treated astrocytes in a time-dependent manner. These data indicated that Tbeta4 attenuates ethanol-induced neurotoxicity in cultured cortical astrocytes through inhibition of apoptosis signaling, and one of the mechanisms underlying the capacity of Tbeta4 to suppress apoptosis may in part be due to its effect of anti-peroxidation.

Transgenic overexpression of aldehyde dehydrogenase-2 rescues chronic alcohol intake-induced myocardial hypertrophy and contractile dysfunction

BACKGROUND

Chronic alcoholism leads to the onset and progression of alcoholic cardiomyopathy through toxic mechanisms of ethanol and its metabolite, acetaldehyde. This study examined the impact of altered acetaldehyde metabolism through systemic transgenic overexpression of aldehyde dehydrogenase-2 (ALDH2) on chronic alcohol ingestion-induced myocardial damage.

METHODS AND RESULTS

ALDH2 transgenic mice were produced with the chicken beta-actin promoter. Wild-type FVB and ALDH2 mice were placed on a 4% alcohol diet or a control diet for 14 weeks. Myocardial and cardiomyocyte contraction, intracellular Ca(2+) handling, histology (hematoxylin and eosin, Masson trichrome), protein damage, and apoptosis were determined. Western blot was used to monitor the expression of NADPH oxidase, calcineurin, apoptosis-stimulated kinase (ASK-1), glycogen synthase kinase-3beta (GSK-3beta), GATA4, and cAMP-response element binding (CREB) protein. ALDH2 reduced the chronic alcohol ingestion-induced elevation in plasma and tissue acetaldehyde levels. Chronic alcohol consumption led to cardiac hypertrophy, reduced fractional shortening, cell shortening, and impaired intracellular Ca(2+) homeostasis, the effect of which was alleviated by ALDH2. In addition, the ALDH2 transgene significantly attenuated chronic alcohol intake-induced myocardial fibrosis, protein carbonyl formation, apoptosis, enhanced NADPH oxidase p47(phox) and calcineurin expression, as well as phosphorylation of ASK-1, GSK-3beta, GATA4, and CREB.

CONCLUSIONS

The present results suggest that transgenic overexpression of ALDH2 effectively antagonizes chronic alcohol intake-elicited myocardial hypertrophy and contractile defect through a mechanism that is associated, at least in part, with phosphorylation of ASK-1, GSK-3beta, GATA4, and CREB. These data strongly support the notion that acetaldehyde may be an essential contributor to the chronic development of alcoholic cardiomyopathy.

Foetal Alcohol Spectrum Disorders and alterations in brain and behaviour

The term 'Foetal Alcohol Spectrum Disorders (FASD)' refers to the range of disabilities that may result from prenatal alcohol exposure. This article reviews the effects of ethanol on the developing brain and its long-term structural and neurobehavioural consequences. Brain imaging, neurobehavioural and experimental studies demonstrate the devastating consequences of prenatal alcohol exposure on the developing central nervous system (CNS), identifying specific brain regions affected, the range of severity of effects and mechanisms involved. In particular, neuroimaging studies have demonstrated overall and regional volumetric and surface area reductions, abnormalities in the shape of particular brain regions, and reduced and increased densities for white and grey matter, respectively. Neurobehaviourally, FASD consists of a continuum of long-lasting deficits affecting multiple aspects of cognition and behaviour. Experimental studies have also provided evidence of the vulnerability of the CNS to the teratogenic effects of ethanol and have provided new insight on the influence of risk factors in the type and severity of observed brain abnormalities. Finally, the potential molecular mechanisms that underlie the neuroteratological effects of alcohol are discussed, with particular emphasis on the role of glial cells in long-term neurodevelopmental liabilities.

Mechanisms of alcoholic heart disease

Compromised heart function is regularly seen in patients with chronic alcohol ingestion and is often manifested as cardiomegaly, reduced myocardial contractility (with concomitant reductions in ejection fraction and stroke volume), myocardial fibrosis, enhanced risk of stroke and hypertension, and disruptions in the myofibrillary structure. A number of mechanisms including oxidative damage, deposition of triglycerides, altered fatty acid extraction, decreased myofilament Ca(2+) sensitivity, and impaired protein synthesis have been proposed for the development of alcoholic cardiomyopathy. Nonetheless, the underlying mechanism(s) has not been delineated. Several alcohol metabolites have been identified as specific toxins of myocardial tissue, including ethanol, its first and major metabolic product--acetaldehyde--and fatty acid ethyl esters. Acetaldehyde directly impairs cardiac contractile function, disrupts cardiac excitation-contraction coupling and promotes oxidative damage and lipid peroxidation. Unfortunately, the most direct approach to studying this (direct administration of acetaldehyde) is impossible, since direct intake of acetaldehyde is highly toxic and unsuitable for chronic studies. In order to overcome this obstacle, transgenic mice have recently been produced to artificially alter ethanol/acetaldehyde metabolism, resulting in elevated acetaldehyde levels after ethanol ingestion. This review will summarize some of the postulated mechanisms for alcoholic cardiomyopathy, with special emphasis on animal models.

Markers of oxidative stress and systemic vasoconstriction in pregnant women drinking > or =48 g of alcohol per day

BACKGROUND

The precise pathway by which alcohol causes the characteristic features of fetal alcohol spectrum disorders is unknown. Proposed mechanisms for fetal injury from maternal alcohol use include cellular damage from oxidative stress and impaired fetal oxygenation related to maternal systemic vasoconstriction. Our objective was to compare the levels of urinary markers of oxidative stress and systemic vasoconstriction between women consuming large amounts of alcohol during pregnancy and women who did not drink alcohol during pregnancy.

METHODS

Pregnant women consuming > or =48 g alcohol per day (n = 29) on average and pregnant women who abstained from alcohol use (n = 39) were identified using detailed interviews and home visits. Random maternal urine specimens were collected. Urinary levels of the oxidative stress marker, 8-isoprostane F2alpha, and of the vasoactive prostaglandin metabolites, 2,3-dinor-6-keto-prostaglandin F1alpha (a vasodilator) and 11-dehydro-thromboxane B2 (a vasoconstrictor), were measured using mass spectrometric methods. All analyte levels were corrected for urinary creatinine.

RESULTS

In crude analyses, there was no significant difference in 8-isoprostane F2alpha between pregnant drinkers and nondrinkers (2.16 vs. 2.08 ng/mg creatinine, respectively, p = 0.87). There were no significant differences between the drinking and nondrinking groups in levels of 2,3-dinor-6-keto-prostaglandin F1alpha (1.03 vs. 1.17 ng/mg creatinine, respectively, p = 0.50), 11-dehydro-thromboxane B2 (0.72 vs. 0.59 ng/mg creatinine, respectively, p = 0.21), or the ratio of vasodilatory metabolite to vasoconstrictive metabolite (1.73 vs. 2.72, respectively, p = 0.14). Adjusting for maternal age, marital status, smoking, and gestational age at sampling did not substantially alter the results.

CONCLUSION

Our results show no difference in levels of urinary eicosanoid markers of oxidative stress and systemic vasoconstriction between pregnant women who drink heavily and pregnant women who abstain. These findings speak against a role for maternal oxidative stress or systemic vasoconstriction in the pathogenesis of alcohol damage to the fetus.

RETRACTED: Cardiac overexpression of alcohol dehydrogenase exacerbates chronic ethanol ingestion-induced myocardial dysfunction and hypertrophy: role of insulin signaling and ER stress

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). At the request of the University of Wyoming, this article has been retracted. The University of Wyoming's institutional investigation of the work authored by Dr. Jun Ren found evidence of data irregularities in Figures 2, 3 and 4 that affect the reported results and conclusions. All authors have been notified of the retraction of this article.

Oxidative stress, chronic disease, and muscle wasting

Underlying the pathogenesis of chronic disease is the state of oxidative stress. Oxidative stress is an imbalance in oxidant and antioxidant levels. If an overproduction of oxidants overwhelms the antioxidant defenses, oxidative damage of cells, tissues, and organs ensues. In some cases, oxidative stress is assigned a causal role in disease pathogenesis, whereas in others the link is less certain. Along with underlying oxidative stress, chronic disease is often accompanied by muscle wasting. It has been hypothesized that catabolic programs leading to muscle wasting are mediated by oxidative stress. In cases where disease is localized to the muscle, this concept is easy to appreciate. Transmission of oxidative stress from diseased remote organs to skeletal muscle is thought to be mediated by humoral factors such as inflammatory cytokines. This review examines the relationship between oxidative stress, chronic disease, and muscle wasting, and the mechanisms by which oxidative stress acts as a catabolic signal.

Difluoromethylornithine decreases long-lasting protein oxidation induced by neonatal ethanol exposure in the hippocampus of adolescent rats

BACKGROUND

Ethanol exposure and withdrawal during central nervous system development can cause oxidative stress and produce severe and long-lasting behavioral and morphological alterations in which polyamines seem to play an important role. However, it is not known if early ethanol exposure causes long-lasting protein oxidative damage and if polyamines play a role in such a deleterious effect of ethanol.

METHODS

In this study we investigated the effects of early ethanol exposure (6 g/kg/d, by gavage), from postnatal day (PND) 1 to 8, and of the administration of difluoromethylornithine (DFMO, 500 mg/kg, i.p., on PND 8), a polyamine biosynthesis inhibitor, on the extent of oxidative modification of proteins. Indices of oxidative modification of proteins included protein carbonyls, 3-nitrotyrosine (3-NT), and protein bound 4-hydroxynonenal (HNE) in the hippocampus, cerebellum, hypothalamus, striatum, and cerebral cortex of Sprague-Dawley rats at PND 40.

RESULTS

Both ethanol and DFMO administration alone increased protein carbonyl immunoreactivity in the hippocampus at PND 40, but the combination of DFMO and ethanol resulted in no effect on protein carbonyl levels. No alterations in the content of protein-bound HNE, 3-NT, or carbonyl were found in any other cerebral structure.

CONCLUSIONS

These results suggest that the hippocampus is selectively affected by early ethanol exposure and by polyamine synthesis inhibition. In addition, the results suggest a role for polyamines in the long-lasting increase of protein carbonyls induced by ethanol exposure and withdrawal.

Ethanol-Induced Fetal Dysmorphogenesis in the Mouse Is Diminished by High Antioxidative Capacity of the Mother

Intrauterine exposure to ethanol causes embryonic and fetal maldevelopment. Oxidative stress in mother and offspring has been suggested to be part of the teratogenic mechanism of ethanol. Here we aimed to assess the importance of maternal and fetal antioxidative capability for the risk of dysmorphogenesis in the offspring. We used male and female mice with different levels of superoxide dismutase (SOD) activity-wild-type (WT) mice, mice with a targeted SOD mutation (KO, decreased CuZnSOD mRNA), and mice transgenic for SOD (TG, increased CuZnSOD mRNA). Female WT, KO (heterozygous), and TG (heterozygous) mice were given drinking water containing 20% ethanol before and throughout gestation. Non-ethanol-exposed WT, KO, and TG mice served as controls. The female mice were mated with males with identical genotype, and the pregnancy was interrupted on gestational day 18 when the offspring was evaluated and genotyped. Fetal hepatic isoprostane (8-epi-PGF(2alpha)) levels were measured to assess the degree of fetal oxidative stress. Exposure to 20% ethanol decreased fetal weight by 9-13% in the three groups. Ethanol exposure roughly doubled the rates of maldeveloped WT and KO offspring but did not affect TG offspring. The fetal hepatic levels of 8-epi-PGF(2alpha) were increased in the ethanol-exposed WT and KO mice but not in ethanol-exposed TG mice. Ethanol exposure preferentially damaged WT fetuses in pregnant KO mice, whereas no such effect was found in the litters of ethanol-consuming TG mice. Administration of ethanol to pregnant mice disturbs embryogenesis by oxidative stress, and the adverse effects are more pronounced in offspring of mice with low antioxidative capacity.

Cardiac overexpression of catalase antagonizes ADH-associated contractile depression and stress signaling after acute ethanol exposure in murine myocytes

Alcohol dehydrogenase (ADH), which oxidizes ethanol into acetaldehyde, exacerbates ethanol-induced cardiac depression, although the mechanism of action remains unclear. This study was designed to examine the impact of antioxidant catalase (CAT) on cardiac contractile response to ethanol and activation of stress signaling. ADH-CAT double transgenic mice were generated by crossing CAT and ADH lines. Mechanical, intracellular Ca(2+) properties and reactive oxygen species generation were measured in ventricular myocytes. ADH-CAT, ADH, CAT and wild-type FVB myocytes exhibited similar mechanical and intracellular Ca(2+) properties. ADH or ADH-CAT myocytes had higher acetaldehyde-producing ability. Ethanol (80-640 mg/dl) suppressed FVB cell shortening and intracellular Ca(2+) transients with maximal inhibitions of 43.5 and 45.2%, respectively. Ethanol-induced depression on cell shortening and intracellular Ca(2+) was augmented in ADH group with maximal inhibitions of 66.8 and 69.6%, respectively. Interestingly, myocytes from CAT-ADH mice displayed normal ethanol response with maximal inhibitions of 46.0 and 47.2% for cell shortening and intracellular Ca(2+), respectively. CAT transgene lessened ethanol-induced inhibition on cell shortening (maximal inhibition of 30.3%) but not intracellular Ca(2+). ADH amplified ethanol-induced reactive oxygen species generation, which was nullified by the CAT transgene. Western blot analysis showed that ethanol reduced ERK phosphorylation and enhanced JNK phosphorylation without affecting p38 phosphorylation. The ethanol-induced changes in phosphorylation of ERK and JNK were amplified by ADH. CAT transgene itself did not affect ethanol-induced response in ERK and JNK phosphorylation, but it cancelled ADH-induced effects. These data suggest that antioxidant CAT may effectively antagonize ADH-induced enhanced cardiac depression in response to ethanol.

Vitamin E therapy prevents hyperoxaluria-induced calcium oxalate crystal deposition in the kidney by improving renal tissue antioxidant status

OBJECTIVE

To determine whether vitamin E prevents hyperoxaluria-induced stone formation, using a new animal model of calcium oxalate stone disease, as our previous in- vitro and in-vivo studies showed that oxalate and hyperoxaluria induce free-radical generation, which results in peroxidative injury to renal tubular cells.

MATERIALS AND METHODS

Ethylene glycol (EG) was administered at 150 mg/day by gavage for 3 weeks to rats fed on diets with adequate (group 1), excess (group 2) or deficient (group 3) vitamin E. Several indicators of peroxidation, free radicals and enzymatic activity were then assessed.

RESULTS

EG treatment in group 1 lead to increased lipid peroxidation, protein thiol, excretion of urinary enzymes, oxalate and decreases in urinary calcium, antioxidant enzymes and altered glutathione redox balance. Although renal function was not altered, there was increased water intake, urine volume and lowered urinary pH in these rats. These changes were more intense, with extensive calcium-oxalate crystal deposition, in rats in group 3, and prevented in rats in group 2, except for urinary oxalate levels, which remained high. Histopathological examination showed that there was no deposition of calcium oxalate crystals in rats in group 2.

CONCLUSION

This is the first study to demonstrate in-vivo evidence that hyperoxaluria-induced peroxidative injury induces individual calcium oxalate crystal attachment in the renal tubules. In addition, excess vitamin E completely prevented calcium oxalate deposition, by preventing peroxidative injury and restoring renal tissue antioxidants and glutathione redox balance. Therefore, vitamin E therapy might provide protection against the deposition of calcium oxalate stones in the kidney of humans.

A critical role of Pax6 in alcohol-induced fetal microcephaly

Maternal alcohol abuse during pregnancy is one of the leading causes of birth defects in humans. Despite extensive studies, the molecular basis is still not clear. Here we transiently exposed Xenopus embryos to alcohol and showed that alcohol dose-dependently produced microcephaly and growth retardation. Moreover, it reduced the expression of several key neural genes (xPax6, xOtx2, xSox3, xSox2, and xNCAM), of which xPax6 was most vulnerable. An alcohol concentration as low as 0.3% could produce more than 90% reduction of xPax6 expression. Consistently, microinjection of xPax6 expression plasmid to Xenopus embryos dose-dependently rescued alcohol-induced microcephaly and restored the expression of xOtx2, xSox3, xSox2, and xNCAM. To test whether reactive oxygen species (ROS) is the upstream signal for alcohol-induced microcephaly and xPax6 suppression, we overexpressed catalase in Xenopus embryos and found that catalase not only decreased alcohol-induced H(2)O(2) formation, but also fully restored Pax6 expression and reversed microcephaly. In contrast, xPax6 and catalase could only provide partial protection against growth retardation. Results from this study illustrate for the first time the critical role of H(2)O(2)-mediated Pax6 suppression in alcohol-induced microcephaly and suggest the presence of additional mechanisms for alcohol-induced fetal growth retardation.

Protection of Xenopus laevis Embryos Against Alcohol-induced Delayed Gut Maturation and Growth Retardation by Peroxiredoxin 5 and Catalase

Accumulated evidence indicates that maternal alcohol consumption causes fetal enteric damage and growth retardation. In this study, we investigated the underlying molecular mechanisms in a Xenopus model of fetal alcohol exposure. We established a condition of transient alcohol exposure that produces tadpoles with delayed gut maturation and decreased body length. We then investigated the roles of reactive oxygen species (ROS) and reactive nitrogen species (RNS) by microinjecting plasmids expressing catalase and peroxiredoxin 5 (PRDX5) into two-cell stage embryos. Finally, the effects of these enzymes on the expression of key gut developmental genes were determined by animal cap explant assay. We showed that exposure of Xenopus embryos to 0.5% alcohol from stage 13 to stage 22 produced tadpoles with delayed gut maturation, reduced growth, and down-regulation in several gut developmental genes, with VegT, Pax6 and Sox17 most vulnerable. We further demonstrated that microinjection of catalase attenuated alcohol-induced ROS production and restored the expression of VegT and Pax6, but protected the embryos from delayed gut development and retarded growth only partially. By contrast, microinjection of PRDX5 reduced both ROS and RNS production, and prevented the gut and growth defects, and restored VegT, Pax6 and Sox17 gene expression. A positive correlation was found between delayed gut maturation and reduced body length. These results indicate the crucial roles of both the ROS-Pax6 and RNS-Sox17 signaling axes in alcohol-induced fetal gut defects and growth retardation. In addition, they suggest strongly a cause-and-effect relationship between alcohol-induced delayed gut maturation and growth retardation.

Alcoholic muscle disease and biomembrane perturbations (review)

Excessive alcohol ingestion is damaging and gives rise to a number of pathologies that influence nutritional status. Most organs of the body are affected such as the liver and gastrointestinal tract. However, skeletal muscle appears to be particularly susceptible, giving rise to the disease entity alcoholic myopathy. Alcoholic myopathy is far more common than overt liver disease such as cirrhosis or gastrointestinal tract pathologies. Alcohol myopathy is characterised by selective atrophy of Type II (anaerobic, white glycolic) muscle fibres: Type I (aerobic, red oxidative) muscle fibres are relatively protected. Affected patients have marked reductions in muscle mass and impaired muscle strength with subjective symptoms of cramps, myalgia and difficulty in gait. This affects 40-60% of chronic alcoholics (in contrast to cirrhosis, which only affects 15-20% of chronic alcohol misuers).Many, if not all, of these features of alcoholic myopathy can be reproduced in experimental animals, which are used to elucidate the pathological mechanisms responsible for the disease. However, membrane changes within these muscles are difficult to discern even under the normal light and electron microscope. Instead attention has focused on biochemical and other functional studies. In this review, we provide evidence from these models to show that alcohol-induced defects in the membrane occur, including the formation of acetaldehyde protein adducts and increases in sarcoplasmic-endoplasmic reticulum Ca(2+)-ATPase (protein and enzyme activity). Concomitant increases in cholesterol hydroperoxides and oxysterol also arise, possibly reflecting free radical-mediated damage to the membrane. Overall, changes within muscle membranes may reflect, contribute to, or initiate the disturbances in muscle function or reductions in muscle mass seen in alcoholic myopathy. Present evidence suggest that the changes in alcoholic muscle disease are not due to dietary deficiencies but rather the direct effect of ethanol or its ensuing metabolites.

Ethanol and acetaldehyde in alcoholic cardiomyopathy: from bad to ugly en route to oxidative stress

Alcoholic cardiomyopathy is characterized by cardiomegaly, disruptions of myofibrillary architecture, reduced myocardial contractility, decreased ejection fraction, and enhanced risk of stroke and hypertension. Although several mechanisms have been postulated for alcoholic cardiomyopathy, including oxidative damage, accumulation of triglycerides, altered fatty acid extraction, decreased myofilament Ca(2+) sensitivity, and impaired protein synthesis, neither the mechanism nor the ultimate toxin has been unveiled. Primary candidates acting as specific toxins of myocardial tissue are ethanol; its first and major metabolic product, acetaldehyde; and fatty acid ethyl esters. Acetaldehyde has been demonstrated to impair directly cardiac contractile function, disrupt cardiac excitation-contractile coupling, and contribute to oxidative damage and lipid peroxidation. Acetaldehyde-elicited cardiac dysfunction may be mediated through cytochrome P450 oxidase, xanthine oxidase, and the stress-signaling cascade. Unfortunately, the most direct approach that can be used to examine toxicity is hampered by the fact that direct intake of acetaldehyde is highly toxic and unsuitable for long-term study. To overcome this obstacle, transgenic mice have been used to alter artificially ethanol/acetaldehyde metabolism, resulting in elevated acetaldehyde concentrations after ethanol ingestion. In this review, we summarize results obtained with the use of transgenic animal models to elucidate the role of acetaldehyde in the mechanism of action in alcoholic cardiomyopathy.

Overexpression of aldehyde dehydrogenase-2 (ALDH2) transgene prevents acetaldehyde-induced cell injury in human umbilical vein endothelial cells: role of ERK and p38 mitogen-activated protein kinase

Acetaldehyde, the major ethanol metabolite that is far more toxic and reactive than ethanol, has been postulated to be responsible for alcohol-induced tissue and cell injury. This study was to examine whether facilitated acetaldehyde metabolism affects acetaldehyde-induced oxidative stress and apoptosis. Transgene-encoding human aldehyde dehydrogenase-2 (ALDH2), which converts acetaldehyde into acetate, was constructed under chicken beta-actin promoter and transfected into human umbilical vein endothelial cells (HUVECs). Efficacy of ALDH2 transfection was verified using green fluorescent protein and ALDH2 enzymatic assay. Generation of reactive oxygen species (ROS) was measured using chloromethyl-2',7'-dichlorodihydrofluorescein diacetate. Apoptosis was evaluated by 4',6'-diamidino-2'-phenylindoladihydrochloride fluorescence microscopy, quantitative DNA fragmentation, and caspase-3 assay. Acetaldehyde (0-200 microm) elicited ROS generation and apoptosis in HUVECs in a time- and concentration-dependent manner, associated with activation of the stress signal molecules ERK1/2 and p38 mitogen-activated protein (MAP) kinase. A close liner correlation was observed between the acetaldehyde-induced ROS generation and apoptosis. Interestingly, the acetaldehyde-induced ROS generation, apoptosis, activation of ERK1/2, and p38 MAP kinase were prevented by the ALDH2 transgene or antioxidant alpha-tocopherol. The involvement of ERK1/2 and p38 MAP kinase in acetaldehyde-induced apoptosis was confirmed by selective kinase inhibitors U0126, SB203580, and SB202190. Collectively, our data revealed that facilitation of acetaldehyde metabolism by ALDH2 transgene overexpression may prevent acetaldehyde-induced cell injury and activation of stress signals. These results indicated therapeutic potential of ALDH2 enzyme in the prevention and detoxification of acetaldehyde or alcohol-induced cell injury.

Role of naringin supplement in regulation of lipid and ethanol metabolism in rats

The current study was performed to investigate the effect of naringin supplements on the alcohol, lipid, and antioxidant metabolism in ethanol-treated rats. Male Sprague-Dawley rats were randomly divided into six groups (n = 10) based on six dietary categories: ethanol and naringin-free, ethanol (50 g/L) plus low-naringin (0.05 g/L), ethanol plus high-naringin (0.125 g/L), and three corresponding pair-fed groups. The pair-fed control rats received an isocaloric diet containing dextrin-maltose instead of ethanol for 5 wks. Among the ethanol treated groups, the naringin supplements significantly lowered the plasma ethanol concentration with a simultaneous increase in the ADH and/or ALDH activities. However, among the ethanol-treated groups, naringin supplementation resulted in a significant decrease in the hepatic triglycerides and plasma and hepatic total cholesterol compared to that in the naringin-free group. Naringin supplementation significantly increased the HDL-cholesterol and HDL-C/total-C ratio, while lowering the AI value among the ethanol-treated groups. Hepatic lipid accumulation was also significantly reduced in the naringin-supplemented groups compared to the naringin-free group among the ethanol-treated groups, while no differences were found among the pair-fed groups. Among the ethanol-treated groups, the low-naringin supplementation resulted in a significant decrease in the levels of plasma and hepatic TBARS, whereas it resulted in higher SOD and GSH-Px activities and gluthathion levels in the liver. Accordingly, naringin would appear to contribute to alleviating the adverse effect of ethanol ingestion by enhancing the ethanol and lipid metabolism as well as the hepatic antioxidant defense system.

Cardiac overexpression of alcohol dehydrogenase exacerbates cardiac contractile dysfunction, lipid peroxidation, and protein damage after chronic ethanol ingestion

BACKGROUND

Alcoholic cardiomyopathy is manifested as ventricular dysfunction, although its specific toxic mechanism remains obscure. This study was designed to examine the impact of enhanced acetaldehyde exposure on cardiac function via cardiac-specific overexpression of alcohol dehydrogenase (ADH) after alcohol intake.

METHODS

ADH transgenic and wild-type FVB mice were placed on a 4% alcohol or control diet for 8 weeks. Mechanical and intracellular Ca2+ properties were evaluated in cardiac myocytes. Levels of acetaldehyde, lipid peroxidation, and protein carbonyl formation were determined.

RESULTS

FVB and ADH mice consuming ethanol exhibited elevated blood ethanol/acetaldehyde, cardiac acetaldehyde, and cardiac hypertrophy compared with non-ethanol-consuming mice. However, the levels of cardiac acetaldehyde and hypertrophy were significantly greater in ADH ethanol-fed mice than FVB ethanol-fed mice. ADH transgene itself did not affect mechanical and intracellular Ca2+ properties with the exception of reduced resting intracellular Ca2+ and Ca2+ re-sequestration at low pace frequency. Myocytes from ethanol-fed mice showed significantly depressed peak shortening, velocity of shortening/relengthening, rise of intracellular Ca2+ transients, and sarco(endo)plasmic reticulum Ca2+ load associated with similar duration of shortening/relengthening compared with myocytes from control mice. Strikingly, the ethanol-induced mechanical and intracellular Ca2+ defects were exacerbated in ADH myocytes compared with the FVB group except velocity of shortening/relengthening. The lipid peroxidation end products malondialdehyde and protein carbonyl formation were significantly elevated in both livers and hearts after chronic ethanol consumption, with the cardiac lipid and protein damage being exaggerated by ADH transgene.

CONCLUSION

These data suggest that increased cardiac acetaldehyde exposure due to ADH transgene may play an important role in cardiac contractile dysfunctions associated with lipid and protein damage after alcohol intake.

Influence of gender on ethanol-induced ventricular myocyte contractile depression in transgenic mice with cardiac overexpression of alcohol dehydrogenase

Acute ethanol exposure depresses ventricular contractility and contributes to alcoholic cardiomyopathy in both men and women chronically consuming ethanol. However, a gender-related difference in the severity of myopathy exists with female being more sensitive to ethanol-induced tissue damage. Acetaldehyde (ACA), the major oxidized product of ethanol, has been implicated to play a role in the pathogenesis and gender-related difference of alcoholic cardiomyopathy, possibly due to its direct cardiac effect and interaction with estrogen. This study was designed to compare the effects of cardiac overexpression of alcohol dehydrogenase (ADH), which converts ethanol into ACA, on the cardiac contractile response to ethanol in ventricular myocytes isolated from age-matched adult male and female transgenic (ADH) and wild-type (FVB) mice. Mechanical properties were measured with an IonOptix SoftEdge system. ACA production was assessed by gas chromatography. The ADH myocytes from both genders exhibited similar mechanical properties but a higher efficacy to produce ACA compared to FVB myocytes. Exposure to ethanol (80-640 mg/dl) for 60 min elicited concentration-dependent decrease of cell shortening in both FVB and ADH groups. The ethanol-induced depression on cell shortening was significantly augmented in female but not male ADH group. ADH transgene did not exacerbate the ethanol-induced inhibition of maximal velocity of shortening/relengthening in either gender. In addition, neither ethanol nor ADH transgene affect the duration of shortening and relengthening in male or female mice. These data suggest that females may be more sensitive to ACA-induced cardiac contractile depression than male, which may attribute to the gender-related difference of alcoholic cardiomyopathy.

Mechanisms involved in central nervous system dysfunctions induced by prenatal ethanol exposure

Clinical and experimental evidence has demonstrated that ethanol is a teratogen, and that its consumption during pregnancy induces harmful effects on the developing foetus that leads to foetal alcohol syndrome (FAS). Central nervous system dysfunctions are the most severe and permanent consequence of maternal alcohol intake and can occur in absence of gross morphological defects associated with FAS. Mental retardation and long-term cognitive and behavioural deficits are some of the problems commonly found in children of women who were moderate or heavy drinkers during pregnancy. Experimental evidence demonstrates that alcohol interferes with many molecular, neurochemical and cellular events occurring during the normal development of the brain. Some brain areas are more affected than others and, even within a given region, some cell populations are more vulnerable than others. The neocortex, hippocampus and cerebellum are especially susceptible to alcohol and have been associated with the behavioural deficits. For example, alcohol exposure during the development of neocortex increases natural apoptosis and induces cell necrosis. These effects may be associated with ethanol-induced alterations in both neurotrophic support, and the expression of cell adhesion molecules, which may affect cell-cell interactions and cell survival. Experimental evidence also shows that alcohol disrupts radial glial and astroglial development which may lead to alterations in cell migration and neuronal survival and differentiation. Impairment of several neurotransmitter systems and/or their receptors, as well as changes in the endocrine environment during brain development, are also important factors involved in the neurodevelopmental liabilities observed after in utero alcohol exposure.

Overexpression of alcohol dehydrogenase exacerbates ethanol-induced contractile defect in cardiac myocytes

Alcoholic cardiomyopathy is characterized by impaired ventricular function although its toxic mechanism is unclear. This study examined the impact of cardiac overexpression of alcohol dehydrogenase (ADH), which oxidizes ethanol into acetaldehyde (ACA), on ethanol-induced cardiac contractile defect. Mechanical and intracellular Ca(2+) properties were evaluated in ventricular myocytes from ADH transgenic and wild-type (FVB) mice. ACA production was assessed by gas chromatography. ADH myocytes exhibited similar mechanical properties but a higher efficiency to convert ACA compared with FVB myocytes. Acute exposure to ethanol depressed cell shortening and intracellular Ca(2+) in the FVB group with maximal inhibitions of 23.3% and 23.4%, respectively. Strikingly, the ethanol-induced depression on cell shortening and intracellular Ca(2+) was significantly augmented in the ADH group, with maximal inhibitions of 43.7% and 40.6%, respectively. Pretreatment with the ADH inhibitor 4-methylpyrazole (4-MP) or the aldehyde dehydrogenase inhibitor cyanamide prevented or augmented the ethanol-induced inhibition, respectively, in the ADH but not the FVB group. The ADH transgene also substantiated the ethanol-induced inhibition of maximal velocity of shortening/relengthening and unmasked an ethanol-induced prolongation of the duration of shortening/relengthening, which was abolished by 4-MP. These data suggest that elevated cardiac ACA exposure due to enhanced ADH expression may play an important role in the development of alcoholic cardiomyopathy.

Effects of Puerariae Flos and Puerariae Radix extracts on antioxidant enzymes in ethanol-treated rats

This study was performed to investigate the effect of Puerariae Flos (PF) and Puerariae Radix (PR) water extracts on the activities and mRNA expression of three hepatic antioxidant enzymes in ethanol-treated rats. Male Sprague-Dawley rats were divided into four groups, a control, ethanol-treated, ethanol plus PF-treated, and ethanol plus PR-treated group with seven rats per group. Ethanol (25 % v/v, 5 g/kg body weight) was orally administered once a day for 5 weeks. The PF and PR water extracts were supplemented in a diet based on 1.2 g of raw PF or PR/kg body weight/day. Ethanol administration without the PF or PR supplement significantly lowered the activities of hepatic Cu/Zn SOD and catalase (CAT), whereas it increased the hepatic GSH-Px activity. However, the PF and PR supplementation resulted in a significant increase in the Cu/Zn SOD and/or CAT activities and a significant decrease in the GSH-Px activity in the ethanol-treated rats. The mRNA levels of these antioxidant enzymes in the ethanol-treated rats were normalized to the control level by the PF or PR supplement. The hepatic glutathione content, which was significantly lower in the ethanol-treated group than in the control group, was also normalized to the control level by supplementing with either PF or PR. The PF or PR supplement resulted in lowering the hepatic malondialdehyde to the control level in the ethanol-treated rats.

Spatial glutathione and cysteine distribution and chemical modulation in the early organogenesis-stage rat conceptus in utero

Glutathione (GSH), cysteine, and other low-molecular-weight thiols (LMWT) play a vital role in the detoxication of xenobiotics and endogenous chemicals. Differential alterations of LMWT status in various cell types of the developing embryo may underlie cell-specific sensitivity or resistance to xenobiotics and contribute to embryotoxicity. This study describes the spatial and temporal distribution of LMWTs in rat conceptuses and alterations produced by the non-teratogenic GSH modulator, acetaminophen (APAP). Pregnant female rats were given 125, 250, or 500 mg/kg APAP (po) on gestational day 9. Conceptal LMWT was localized histochemically using mercury orange in cryosections, and GSH and cysteine concentrations were measured by HPLC analysis. Mercury orange histofluorescence revealed a non-uniform distribution of LMWT in untreated conceptal tissues, with strongest staining observed in the ectoplacental cone (EPC), visceral yolk sac (VYS), and embryonic heart. Less intense staining was observed in the neuroepithelium. Following treatment with APAP, tissue-associated LMWT decreased dramatically except in the EPC, while exocoelomic fluid LMWT, and LMWT within embryonic lumens, increased. Exposure to 250 mg/kg APAP decreased embryonic GSH after 6 and 24 h by 46% and 38%, respectively. Acetaminophen (500 mg/kg) decreased embryonic and VYS cysteine content by 54% and 83%, respectively, after 24 h. Acetaminophen alters the spatial distribution of LMWT in rat conceptuses, particularly with respect to cysteine. The mobilization of cysteine following chemical insult may influence the ability of conceptal cells to maintain normal GSH status due to reduced availability of cysteine for de novo GSH synthesis.

Dose response of ethanol on antioxidant defense system of liver, lung, and kidney in rat

This study investigated the alterations in levels of glutathione, lipid peroxidation, and antioxidant enzyme activity in the liver, lung, and kidney of rats treated with acute doses of ethanol. Male Fisher-344 rats were randomly divided into four groups, and were treated as follows: (1) vehicle (saline) control; (2) ethanol 2 g/kg, p.o.; (3) ethanol 4g/kg, p.o.; and (4) ethanol 6 g/kg, p.o. The animals were sacrificed 1 h after treatment, and tissues were isolated and analyzed. The hepatic GSH levels significantly decreased (73, 68, and 66% of control) due to ethanol ingestion at 2, 4, and 6g/kg, respectively. The hepatic GSH/GSSG ratio also decreased with increasing doses indicating stress response due to ethanol. The hepatic SOD activity significantly decreased (70, 75 and 71% of control) with graded doses of ethanol ingestion. The hepatic CAT/SOD and GSH-Px+CAT/SOD ratios significantly increased (147, 169 and 177% of control) and (140, 167 and 178% of control), respectively with increasing doses of ethanol. In the lung, graded doses of ethanol increased GSH-Px activity (120, 114 and 141% of control) and decreased GR activity (98, 89 and 89% of control), respectively. The MDA concentrations in the lung also increased after higher ethanol ingestion. Most of the antioxidant enzyme ratios increased with increasing doses of ethanol in the lung. In the kidney, GSH-Px activity increased (139, 119 and 151% of control), whereas GR activity decreased (84, 85 and 83% of control). GSH-Px/SOD and GSH-Px+CAT/SOD ratios increased whereas GR/GSH-Px ratio decreased after graded doses of ethanol. GSH levels in the kidney decreased after ethanol ingestion. MDA concentrations increased with increasing dose of ethanol in the kidney. These results showed the dose dependant and tissue specific changes in the antioxidant system after ethanol ingestion. Ethanol exerts oxidative stress on antioxidant systems of liver, lung and kidney in proportion to the amount of ethanol ingestion.

Dose- and time-dependent effects of ethanol on plasma antioxidant system in rat

This study investigates the dose- as well as time-dependent effects of ethanol ingestion on antioxidant system and lipid peroxidation in plasma of the rat. The plasma ethanol concentrations were 154+/-18, 231+/-53, and 268+/-49 mg/dl 1 h after oral ethanol doses of 2, 4, and 6 g/kg, respectively. Superoxide dismutase (SOD) (71%, 56%, and 41 % of control) and glutathione reductase (GR) (71%, 66%, and 55% of control) activity in plasma were significantly decreased in a dose-dependent manner. Catalase (CAT)/SOD and glutathione peroxidase (GSH-Px)/SOD ratios were significantly increased whereas GR/GSH-Px ratio was significantly decreased with increasing dose of ethanol. In a time course study, plasma ethanol concentrations were 177+/-9.7, 143+/-11, 99+/-17, and 26+/-11 mg/dl at 1.5, 2, 4, and 6 h after an oral dose (4 g/kg) of ethanol in rat indicating time-dependent elimination of ethanol. Plasma SOD and GSH-Px activity significantly increased 4-6 h whereas GR activity significantly decreased 2-4 h after ethanol ingestion. The ratio of GR/GSH-Px and the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) in plasma decreased at 1.5-6 h after ethanol ingestion. Plasma malondialdehyde (MDA) levels significantly elevated with respect to an increase in time after ethanol ingestion, indicating time-dependent augmentation of lipid peroxidation. The data indicate that ethanol ingestion perturbs the plasma antioxidant system in a dose- and time-dependent manner. The significant changes in the ratios of CAT/SOD, GSH-Px/SOD, GR/GSH-Px, and GSH/GSSG in plasma may be used as an index of alcohol-induced oxidative stress.