Alcohol and lipids

Experimental Models for Studying Structural and Functional State of the Pathological Liver (Review)

Liver pathologies remain one of the leading causes of mortality worldwide. Despite a high prevalence of liver diseases, the possibilities of diagnosing, prognosing, and treating non-alcoholic and alcoholic liver diseases still have a number of limitations and require the development of new methods and approaches. In laboratory studies, various models are used to reconstitute the pathological conditions of the liver, including cell cultures, spheroids, organoids, microfluidic systems, tissue slices. We reviewed the most commonly used in vivo, in vitro, and ex vivo models for studying non-alcoholic fatty liver disease and alcoholic liver disease, toxic liver injury, and fibrosis, described their advantages, limitations, and prospects for use. Great emphasis was placed on the mechanisms of development of pathological conditions in each model, as well as the assessment of the possibility of reconstructing various key aspects of pathogenesis for all these pathologies. There is currently no consensus on the choice of the most adequate model for studying liver pathology. The choice of a certain effective research model is determined by the specific purpose and objectives of the experiment.

Novel insights into alcoholic liver disease: Iron overload, iron sensing and hemolysis

The liver is the major target organ of continued alcohol consumption at risk and resulting alcoholic liver disease (ALD) is the most common liver disease worldwide. The underlying molecular mechanisms are still poorly understood despite decades of scientific effort limiting our abilities to identify those individuals who are at risk to develop the disease, to develop appropriate screening strategies and, in addition, to develop targeted therapeutic approaches. ALD is predestined for the newly evolving translational medicine, as conventional clinical and health care structures seem to be constrained to fully appreciate this disease. This concept paper aims at summarizing the 15 years translational experience at the Center of Alcohol Research in Heidelberg, namely based on the long-term prospective and detailed characterization of heavy drinkers with mortality data. In addition, novel experimental findings will be presented. A special focus will be the long-known hepatic iron accumulation, the somewhat overlooked role of the hematopoietic system and novel insights into iron sensing and the role of hepcidin. Our preliminary work indicates that enhanced red blood cell (RBC) turnover is critical for survival in ALD patients. RBC turnover is not primarily due to vitamin deficiency but rather to ethanol toxicity directly targeted to erythrocytes but also to the bone marrow stem cell compartment. These novel insights also help to explain long-known aspects of ALD such as mean corpuscular volume of erythrocytes (MCV) and elevated aspartate transaminase (GOT/AST) levels. This work also aims at identifying future projects, naming unresolved observations, and presenting novel hypothetical concepts still requiring future validation.

Alcohol-related liver disease and liver transplantation

Alcohol-related liver disease (ALD) has become the major cause of liver transplantation (LT) in Korea, and is currently the most common cause of LT in Europe and the United States. Although, ALD is one of the most common indications for LT, it is traditionally not considered as an option for patients with ALD due to organ shortages and concerns about relapse. To select patients with terminal liver disease due to ALD for transplants, most LT centers in the United States and European countries require a 6-month sober period before transplantation. However, Korea has a different social and cultural background than Western countries, and most organ transplants are made from living donors, who account for approximately twice as many procedures as deceased donors. Most LT centers in Korea do not require a specific period of sobriety before transplantation in patients with ALD. As per the literature, 8%–20% of patients resume alcohol consumption 1 year after LT, and this proportion increases to 30%–40% at 5 years post-LT, among which 10%–15% of patients resume heavy drinking. According to previous studies, the risk factors for alcohol relapse after LT are as follows: young age, poor familial and social support, family history of alcohol use disorder, previous history of alcohol-related treatment, shorter abstinence before LT, smoking, psychiatric disorders, irregular follow-up, and unemployment. Recognition of the risk factors, early detection of alcohol consumption after LT, and regular follow-up by a multidisciplinary team are important for improving the short- and long-term outcomes of LT patients with ALD.

Hepatic Injury Induced by Dietary Energy Level via Lipid Accumulation and Changed Metabolites in Growing Semi-Fine Wool Sheep

Liver injury threatens the overall health of an organism, as it is the core organ of the animal body. Liver metabolism is affected by numerous factors, with dietary energy level being a crucial one. Therefore, the present study aimed to evaluate hepatic injury and to describe its metabolic mechanism in ruminants fed diets with different dietary energy levels. A total of 25 Yunnan semi-fine wool sheep were fed diets with five dietary metabolic energy levels and were randomly assigned to five groups as follows: low energy (LE), medium–low energy (MLE), medium energy (ME), medium–high energy (MHE), and high energy (HE). The results revealed that the average optical density (AOD) of lipid droplets in the LE, MLE, and HE groups was higher than that in the ME and MHE groups. The enzyme activity of alanine aminotransferase (ALT) was the lowest in the ME group. An increase in dietary energy level promoted the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity and altered the malondialdehyde (MDA) and protein carbonyl (PCO) concentration quadratically. In addition, both high and low dietary energy levels upregulated the mRNA abundance of proinflammatory cytokine interleukin (IL)-1β, nuclear factor-kappa B (NF-κB), and tumor necrosis factor (TNF)-α. Metabonomic analysis revealed that 142, 77, 65, and 108 differential metabolites were detected in the LE, MLE, MHE, and HE groups, compared with ME group respectively. These metabolites were involved in various biochemical pathways, such as glycolipid, bile acid, and lipid metabolism. In conclusion, both high and low dietary energy levels caused hepatic injury. Section staining and metabonomic results revealed that hepatic injury might be caused by altered metabolism and lipid accumulation induced by lipid mobilization.

Assessment of the hyperlipidemia risk for residents exposed to potential emitted metals in the vicinity of a petrochemical complex

Hyperlipidemia, which is associated with certain environmental factors, is a risk factor for cardiovascular disease. Heavy metals are important pollutants from industrial emissions. However, the relationship between the exposure to heavy metals and the occurrence of hyperlipidemia is limited. This study aimed to investigate the association between serum metal levels and the risk of hyperlipidemia in adults living near a petrochemical complex. Our study subjects were 959 residents aged above 35 years in 11 townships near the largest petrochemical complex in central Taiwan. The serum levels of chromium, arsenic, and mercury in the study subjects were measured. The basic characteristics of the study subjects were collected via a questionnaire survey, and the levels of blood lipid biomarkers were analyzed by health examination. The definition of hyperlipidemia was defined in the provided guidelines. Adjusted generalized linear and logistic regression models were applied to evaluate the associations between petrochemical-related metal exposure and hyperlipidemia. The study subjects had chromium, arsenic, and mercury serum levels of 3.24±3.45, 3.45±4.66, and 1.24±1.08 (μg/L), respectively, and close proximity of the study subjects to the petrochemical complex was significantly associated with increased serum metal levels. The results showed that the total cholesterol levels were significantly associated with the increased serum chromium, arsenic, and mercury levels. And, the LDL-C levels were significantly associated with the increased serum mercury levels. In addition, the increased serum arsenic and mercury levels of the study subjects were significantly associated with higher odds ratios for abnormal total cholesterol levels and the risk of hyperlipidemia. Residing in close proximity to a petrochemical complex and high arsenic and mercury exposure were associated with elevated blood lipid levels and an increased risk of hyperlipidemia among the residential population in the vicinity of the petrochemical industry.

Association of Alcohol Intake and Fracture Risk in Elderly Varied by Affected Bones: A Nationwide Longitudinal Study

OBJECTIVE

Previous studies investigating association of alcohol intake and fracture risk in elderly yielded conflicting results. We first examined the association between alcohol intake and total fracture risk in elderly subjects and further analyzed whether the association varied by fracture locations.

METHODS

This is a nationwide population-based cohort study which included all people aged 66 (n=1,431,539) receiving the National Screening Program during 2009-2014. Time-to-event were defined as duration from study recruitment, the day they received health screening, to the occurrence of fracture.

RESULTS

Total fracture was significantly lower in mild drinkers [adjusted hazard ratio (aHR)=0.952; 95% confidence interval (95% CI) =0.931-0.973] and higher in heavy drinkers (aHR=1.246; 95% CI=1.201-1.294) than non-drinkers. Risk pattern of alcohol consumption and fracture differed according to affected bones. Similar J-shaped trends were observed for vertebra fractures, but risk of limb fracture showed a linear relationship with alcohol intake. For hip fracture, risk decrement was more pronounced in mild and moderate drinkers, and significant increment was noted only in very severe drinkers [≥60 g/day; (aHR)=1.446; 1.162-1.801].

CONCLUSION

Light to moderate drinking generally lowered risk of fractures, but association between alcohol and fracture risk varied depending on the affected bone lesions.

The Alcohol-High-Density Lipoprotein Athero-Protective Axis

Ingestion of alcohol is associated with numerous changes in human energy metabolism, especially that of plasma lipids and lipoproteins. Regular moderate alcohol consumption is associated with reduced atherosclerotic cardiovascular disease (ASCVD), an effect that has been attributed to the concurrent elevations of plasma high-density lipoprotein-cholesterol (HDL-C) concentrations. More recent evidence has accrued against the hypothesis that raising plasma HDL concentrations prevents ASCVD so that other metabolic processes associated with alcohol consumption have been considered. This review explored the roles of other metabolites induced by alcohol consumption-triglyceride-rich lipoproteins, non-esterified free fatty acids, and acetate, the terminal alcohol metabolite in athero-protection: Current evidence suggests that acetate has a key role in athero-protection but additional studies are needed.

Genetic deletion of the circadian clock transcription factor BMAL1 and chronic alcohol consumption differentially alter hepatic glycogen in mice

Multiple metabolic pathways exhibit time-of-day-dependent rhythms that are controlled by the molecular circadian clock. We have shown that chronic alcohol is capable of altering the molecular clock and diurnal oscillations in several elements of hepatic glycogen metabolism ( 19 , 44 ). Herein, we sought to determine whether genetic disruption of the hepatocyte clock differentially impacts hepatic glycogen content in chronic alcohol-fed mice. Male hepatocyte-specific BMAL1 knockout (HBK) and littermate controls were fed control or alcohol-containing diets for 5 wk to alter hepatic glycogen content. Glycogen displayed a significant diurnal rhythm in livers of control genotype mice fed the control diet. While rhythmic, alcohol significantly altered the diurnal oscillation of glycogen in livers of control genotype mice. The glycogen rhythm was mildly altered in livers of control-fed HBK mice. Importantly, glycogen content was arrhythmic in livers of alcohol-fed HBK mice. Consistent with these changes in hepatic glycogen content, we observed that some glycogen and glucose metabolism genes were differentially altered by chronic alcohol consumption in livers of HBK and littermate control mice. Diurnal rhythms in glycogen synthase (mRNA and protein) were significantly altered by alcohol feeding and clock disruption. Alcohol consumption significantly altered Gck, Glut2, and Ppp1r3g rhythms in livers of control genotype mice, with diurnal rhythms of Pklr, Glut2, Ppp1r3c, and Ppp1r3g further disrupted (dampened or arrhythmic) in livers of HBK mice. Taken together, these findings show that chronic alcohol consumption and hepatocyte clock disruption differentially influence the diurnal rhythm of glycogen and various key glycogen metabolism-related genes in the liver. NEW & NOTEWORTHY We report that circadian clock disruption exacerbates alcohol-mediated alterations in hepatic glycogen. We observed differential responsiveness in diurnal rhythms of glycogen and glycogen metabolism genes and proteins in livers of hepatocyte-specific BMAL1 knockout and littermate control mice fed alcohol. Our findings provide new insights into potential mechanisms by which alcohol alters glycogen, an important energy source for liver and other organs.

Patterns of Drinking and Mortality from Different Diseases—An Overview

Alcohol has been linked to a considerable burden of disease worldwide. Recent epidemiological research has shown that dimensions of alcohol exposure other than average volume are causal in the etiology of disease. Based on a systematic, computer-assisted search, this article attempts a qualitative review of this literature. Results show that cardiovascular disease, especially ischaemic heart disease, is linked to patterns of drinking: regular and light to moderate drinking, and drinking with meals are cardioprotective; heavy drinking occasions have been associated with detrimental outcomes and increases in disease risk. For cancers, consumption of spirits is linked to higher risk of cancers of the upper digestive tract. Spirits also may play a particular role in causing liver cirrhosis in addition to heavy drinking occasions. Finally, injuries are especially related to high blood alcohol concentration and to the frequency of heavy drinking occasions. Overall, these findings strongly indicate that alcohol epidemiology should include adequate pattern measures into future research.

Beyond Ischemic Heart Disease: Are There other Health Benefits from Drinking Alcohol?

Evidence is growing that alcohol consumption confers health benefits beyond protection from ischemic heart disease. We review this evidence with regard to cerebrovascular disease, peripheral vascular disease, diabetes, cholelithiasis (gallstones), cognitive functioning, and stress reduction and subjective psychosocial benefits. Other possible benefits are briefly considered. The weight of evidence suggests that low-level alcohol consumption offers some protection against ischemic stroke. The evidence that moderate alcohol consumption protects against diabetes and gallstones is also fairly strong. The possibility of other health benefits cannot be dismissed. For all the conditions considered, more research is indicated. The application of more appropriate statistical techniques, studies of patterns of drinking, and experimental approaches to delineating underlying mechanisms should enable firmer conclusions to be drawn. A better understanding of both the benefits and the risks of alcohol use for individuals and populations will facilitate the development of appropriate program and policy interventions to promote health.

Behavioral health mediators of the link between posttraumatic stress disorder and dyslipidemia

OBJECTIVES

Posttraumatic stress disorder (PTSD) has been linked to dyslipidemia, which is a major risk factor for coronary artery disease. Although this link is thought to reflect response to heightened stress, behavioral health risks, including smoking, alcohol dependence, and poor sleep quality, may mediate the relationship between PTSD and dyslipidemia.

METHODS

To test this hypothesis, serum lipid levels were collected from 220 young adults (18-39 years old), 103 of whom were diagnosed with PTSD.

RESULTS

PTSD and associated depressive symptoms were negatively related to high-density lipoprotein cholesterol (HDL-C), p=.04, and positively related to triglyceride (TG) levels, p=.04. Both associations were mediated by cigarette consumption and poor sleep quality, the latter of which accounted for 83% and 93% of the effect of PTSD and depression on HDL-C and TG, respectively.

CONCLUSIONS

These results complement recent findings highlighting the prominence of health behaviors in linking PTSD with cardiovascular risk.

Diurnal triglyceridemia in relation to alcohol intake in men

Fasting and postprandial triglyceride concentrations largely depend on dietary and lifestyle factors. Alcohol intake is associated with triglycerides, but the effect of alcohol on diurnal triglyceridemia in a free living situation is unknown. During three days, 139 men (range: 18–80 years) measured their own capillary triglyceride (cTG) concentrations daily on six fixed time-points before and after meals, and the total daily alcohol intake was recorded. The impact of daily alcohol intake (none; low, <10 g/day; moderate, 10–30 g/day; high, >30 g/day) on diurnal triglyceridemia was analyzed by the incremental area under the cTG curve (∆cTG-AUC) reflecting the mean of the six different time-points. Fasting cTG were similar between the alcohol groups, but a trend of increased cTG was observed in men with moderate and high alcohol intake after dinner and at bedtime (p for trend <0.001) which persisted after adjustment for age, smoking and body mass index. The ∆cTG-AUC was significantly lower in males with low alcohol intake (3.0 ± 1.9 mmol·h/L) (n = 27) compared to males with no (7.0 ± 1.8 mmol·h/L) (n = 34), moderate (6.5 ± 1.8 mmol·h/L) (n = 54) or high alcohol intake (7.2 ± 2.2 mmol·h/L) (n = 24), when adjusted for age, smoking and body mass index (adjusted p value < 0.05). In males, low alcohol intake was associated with decreased diurnal triglyceridemia, whereas moderate and high alcohol intake was associated with increased triglycerides after dinner and at bed time.

Biochemical and molecular study of the influence of Amaranthus hypochondriacus flour on serum and liver lipids in rats treated with ethanol

Hyperlipidemia and hepatic steatosis are frequent alterations due to alcohol abuse. Amaranth is a pseudocereal with hypolipidemic potential among other nutraceutical actions. Here we study the effect of Amaranthus hypochondriacus (Ah) seeds on serum and liver lipids, and the expression of genes associated to lipid metabolism and liver histology in male Wistar rats intoxicated with ethanol. The animals were divided into four groups; two groups were fed the American Institute of Nutrition 1993 for maintenance diet (AIN-93M), and the other two with AIN-93M containing Ah as protein source. One of each protein group received 20% ethanol in the drinking water, thus obtaining: CC (control casein), EC (ethanol casein), CAh (control Ah) and EAh (ethanol Ah). When comparing EAh vs . EC, we found a positive effect of Ah on lipids, preventing the increment of serum cholesterol (p <0.001), through the higher expression of the LDL receptor (p <0.001); and it also decreased free (p < 0.05) and esterified cholesterol (p <0.01) in liver, probably via the reduction of the 3-hydroxy-3-methylglutaryl coenzyme A reductase expression (p <0.001). We also observed that amaranth contributed to the decrease of fat deposits in liver, probably through the decrease in acetyl-CoA carboxylase alpha (p <0.01), glycerol-3-phosphate acyltransferase 1 (p <0.01) and diacylglycerol O-acyltransferase 2 (p <0.05) expression. The histological study showed a decrease in the fat deposits in the amaranth group when compared to casein; this is consistent with the biochemical and molecular parameters studied in this work. In conclusion, amaranth could be recommended to avoid the alterations in the lipid metabolism induced by alcohol and other harmful agents.

Alcohol depletes coenzyme-Q(10) associated with increased TNF-alpha secretion to induce cytotoxicity in HepG2 cells

Alcohol consumption has been implicated to cause severe hepatic steatosis which is mediated by alcohol dehydrogenase (ADH) activity and CYP(450) 2E1 expression. In this context, the effect of ethanol was studied for its influence on lipogenesis in HepG2 cell which is deficient of ADH and does not express CYP(450) 2E1. The results showed that ethanol at 100mM concentration caused 40% cytotoxicity at 72h as determined by MTT assay. The incorporation of labeled [2-(14)C] acetate into triacylglycerol and phospholipid was increased by 40% and 26% respectively upon 24h incubation, whereas incorporation of labeled [2-(14)C] acetate into cholesterol was not significantly increased. Further, ethanol inhibited HMG-CoA reductase which is a rate-limiting enzyme in the cholesterol biosynthesis. It was observed that, HMG-CoA reductase inhibition was brought about by ethanol as a consequence of decreased cell viability, since incubation of HepG2 cells with mevalonate could not increase the cholesterol content and increase the cell viability. Addition of ethanol significantly increased TNF-alpha secretion and depleted mitochondrial coenzyme-Q(10) which is detrimental for cell viability. But vitamin E (10mM) could partially restore coenzyme-Q(10) and glutathione content with decreased TNF-alpha secretion in ethanol treated cells. Further, lipid peroxidation, glutathione peroxidase and superoxide dismutase enzyme activities remained unaffected. Ethanol decreased glutathione content while, GSH/GSSG ratio was significantly higher compared to other groups showing cellular pro-oxidant and antioxidant balance remained intact. Alanine amino transferase activity was increased by 4.85 folds in cells treated with ethanol confirming hepatocyte damage. Hence, it is inferred that ethanol induced cytotoxicity in HepG2 cells due to coenzyme-Q(10) depletion and increased TNF-alpha secretion.

Pathogenesis of alcoholic liver disease: interactions between parenchymal and non-parenchymal cells

The development of alcoholic liver disease (ALD) is a complex process involving both the parenchymal and non-parenchymal cells in the liver. The impact of ethanol on hepatocytes can be characterized as a condition of organelle stress with multifactorial changes in hepatocellular function accumulating during ethanol exposure. These changes include oxidative stress, mitochondrial dysfunction, decreased methylation capacity, endoplasmic reticulum stress, impaired vesicular trafficking and altered proteasome function. Injury to hepatocytes is attributed, in part, to ethanol metabolism by the hepatocytes. Changes in the structural integrity of hepatic sinusoidal endothelial cells, as well as enhanced inflammation in the liver during ethanol exposure are also important contributors to injury. Activation of hepatic stellate cells initiates the deposition of extracellular matrix proteins characteristic of fibrosis. Kupffer cells, the resident macrophages in the liver, are particularly critical to the onset of ethanol-induced liver injury. Chronic ethanol exposure sensitizes Kupffer cells to activation by lipopolysaccharides via toll-like receptor 4. This sensitization enhances the production of inflammatory mediators, such as tumor necrosis factor-α and reactive oxygen species that contribute to hepatocyte dysfunction, necrosis and apoptosis of hepatocytes and the generation of extracellular matrix proteins leading to fibrosis. In this review we provide an overview of the complex interactions between parenchymal and non-parenchymal cells in the liver during the progression of ethanol-induced liver injury.

Severe hypertriglyceridemia influenced by alcohol (SHIBA)

AIMS

This study was conducted to examine the relationship between triglyceride (TG) levels and a history of excessive drinking in patients with severe hypertriglyceridemia (HT).

METHODS

Alcohol intake as well as other risk factors associated with HT were searched for in case records of 300 patients known to the laboratory to have had a TG level over 11.3 mmol/l.

RESULTS

The majority of severe HT could be attributed to obesity, diabetes mellitus, excessive alcohol consumption or combinations of these. Excessive alcohol intake (over 210 g/week for males; over 140 g/week for females) was recorded for 24% of the total, and for 43% in the highest TG quartile. TG levels were significantly higher in the excessive drinkers (P < 0.001) and in patients with acute pancreatitis (P = 0.001). The incidence of pancreatitis in this cohort was 4% and limited to very high TG levels.

CONCLUSION

Excessive alcohol consumption was recorded in a quarter of patients with severe HT. Patients with the combination of obesity, diabetes and alcohol excess are prone to develop extremely high TG values.

The relation between different dimensions of alcohol consumption and burden of disease: an overview

AIMS

As part of a larger study to estimate the global burden of disease and injury attributable to alcohol: to evaluate the evidence for a causal impact of average volume of alcohol consumption and pattern of drinking on diseases and injuries; to quantify relationships identified as causal based on published meta-analyses; to separate the impact on mortality versus morbidity where possible; and to assess the impact of the quality of alcohol on burden of disease.

METHODS

Systematic literature reviews were used to identify alcohol-related diseases, birth complications and injuries using standard epidemiological criteria to determine causality. The extent of the risk relations was taken from meta-analyses.

RESULTS

Evidence of a causal impact of average volume of alcohol consumption was found for the following major diseases: tuberculosis, mouth, nasopharynx, other pharynx and oropharynx cancer, oesophageal cancer, colon and rectum cancer, liver cancer, female breast cancer, diabetes mellitus, alcohol use disorders, unipolar depressive disorders, epilepsy, hypertensive heart disease, ischaemic heart disease (IHD), ischaemic and haemorrhagic stroke, conduction disorders and other dysrhythmias, lower respiratory infections (pneumonia), cirrhosis of the liver, preterm birth complications and fetal alcohol syndrome. Dose-response relationships could be quantified for all disease categories except for depressive disorders, with the relative risk increasing with increased level of alcohol consumption for most diseases. Both average volume and drinking pattern were linked causally to IHD, fetal alcohol syndrome and unintentional and intentional injuries. For IHD, ischaemic stroke and diabetes mellitus beneficial effects were observed for patterns of light to moderate drinking without heavy drinking occasions (as defined by 60+ g pure alcohol per day). For several disease and injury categories, the effects were stronger on mortality compared to morbidity. There was insufficient evidence to establish whether quality of alcohol had a major impact on disease burden.

CONCLUSIONS

Overall, these findings indicate that alcohol impacts many disease outcomes causally, both chronic and acute, and injuries. In addition, a pattern of heavy episodic drinking increases risk for some disease and all injury outcomes. Future studies need to address a number of methodological issues, especially the differential role of average volume versus drinking pattern, in order to obtain more accurate risk estimates and to understand more clearly the nature of alcohol-disease relationships.

Effect of 2-hydroxy 4-methoxy benzoic acid on an experimental model of hyperlipidaemia, induced by chronic ethanol treatment

The aim of the present study was to determine the effect of 2-hydroxy 4-methoxy benzoic acid (HMBA), the active principle of Hemidesmus indicus, an indigenous Ayurvedic medicinal plant in India. We investigated the effect of HMBA on hyperlipidaemia induced by ethanol, exploring food intake, body weight, and hepatic and plasma lipids and lipoproteins. Male Wistar rats weighing 130–180 g were given ethanol (5 g kg−1 p.o.) daily for 30 days. Subsequently, ethanol-fed rats were given HMBA intragastrically at a dose of 200 μg kg−1 per day for 30 days. At the end of the total experimental period of 60 days, plasma concentrations of total cholesterol (CHO), triglycerides (TG), lipoproteins (LP), phospholipids (PL), free fatty acids (FFA) and lipoprotein lipase (LPL), and hepatic CHO, TG and PL were measured. Treatment of ethanol-fed rats with HMBA significantly decreased plasma CHO, TG, LP, PL and FFA and hepatic CHO, TG and PL, and increased plasma LPL concentrations compared with values in untreated ethanol-fed rats (all P &lt; 0.05). Food intake and average body weight at the end of the experimental period were significantly increased by HMBA administration. In conclusion, administration of HMBA decreased lipids and lipoprotein concentrations significantly in an animal model of ethanol-induced hyperlipidaemia.

Overconsumption of dietary fat and alcohol: mechanisms involving lipids and hypothalamic peptides

The studies described in this report provide interesting animal models for exploring some of the metabolic and neural antecedents to the over-consumption of fat and alcohol. The results provide strong support for the existence of positive feedback loops that involve a close relation between circulating lipids and orexigenic peptides in dorsal regions of the hypothalamus. The peptides involved in these circuits include galanin, enkephalin, dynorphin and orexin. These peptides are expressed in the paraventricular nucleus and perifornical lateral hypothalamus, and they have very different functions from peptides expressed in the arcuate nucleus. Through mechanisms involving circulating lipids that rise on energy-dense diets, these peptides in the dorsal hypothalamus are each increased by the consumption of fat and ethanol; these nutrients, in turn, stimulate further production of these same peptides that promote overeating and excess drinking. These mechanisms involving non-homeostatic, positive feedback circuits may be required under conditions when food supplies are scarce and periods of gorging are essential to survival. However, they have pathological and sometimes life-threatening consequences in modern society, where fat-rich foods and alcoholic drinks are abundantly available and are contributing to the marked rise over the past 25 years in obesity and diabetes in both children and adults.

Effect of ethanol on hypothalamic opioid peptides, enkephalin, and dynorphin: relationship with circulating triglycerides

BACKGROUND

Recent evidence has demonstrated that ethanol intake can stimulate the expression and production of the feeding-stimulatory peptide, galanin (GAL), in the hypothalamic paraventricular nucleus (PVN), and that PVN injection of this peptide, in turn, can increase the consumption of ethanol. To test the hypothesis that other feeding-related systems are involved in ethanol intake, this study examined the effect of ethanol on the hypothalamic opioid peptides, enkephalin (ENK), and dynorphin (DYN).

METHOD

Adult, male Sprague-Dawley rats were trained to voluntarily drink increasing concentrations of ethanol, up to 9% v/v, on a 12-hour access schedule or were given a single injection of ethanol (10% v/v) versus saline vehicle. The effect of ethanol on GAL, ENK, and DYN mRNA was measured using real-time quantitative polymerase chain reaction and radiolabeled in situ hybridization, while radioimmunoassay was used to measure peptide levels. In addition to blood alcohol, circulating levels of triglycerides (TG), leptin, and insulin were also measured.

RESULTS

The data demonstrated that: (1) rats voluntarily drinking 9% v/v ethanol (approximately 2.0 g/kg/d) show a significant increase in GAL, ENK, and DYN mRNA in the PVN compared with water-drinking rats; (2) voluntary consumption of ethanol also increases peptide levels of ENK and DYN in the PVN; (3) acute injection of 10% ethanol (1.0 g/kg of 10% v/v) similarly increases the expression of GAL, ENK, and DYN in the PVN; and (4) ethanol consumption and injection, while having little effect on leptin and insulin, consistently increase circulating levels of TG as well as alcohol, both of which are strongly, positively correlated with peptide expression in the PVN.

CONCLUSIONS

These findings, together with published studies, suggest a possible role for hypothalamic opioid peptides in the drinking of ethanol. Based on evidence that dietary fat and lipid injections stimulate the PVN peptides and injection of the opiates and GAL increase ethanol intake, it is proposed that both TG and alcohol in the circulation, which are elevated by the ingestion or injection of ethanol, are involved in stimulating these peptides in the PVN, which in turn promote further consumption of ethanol.

Antecedent ethanol ingestion prevents postischemic microvascular dysfunction

Prolonged ischemia followed by reperfusion (I/R) results in impaired endothelial cell function in all segments of the microvasculature. Moreover, microcirculatory dysfunction plays a major role in the genesis of the reperfusion component of total tissue injury in I/R. Thus, preservation of endothelial function is an important therapeutic goal for ameliorating injury in tissues subjected to I/R. An accumulating body of evidence indicates that low to moderate ethanol consumption produces an adaptive transformation to a protected phenotype in both microvascular endothelium and parenchymal cells such that they are rendered resistant to the pathologic effects of I/R. The purpose of this review is to summarize our current understanding of the signaling pathways underlying the development of the preconditioned state induced by antecedent ethanol in arteriolar, capillary, and venular endothelium. In addition, we will highlight understudied areas with regard to microvascular protection afforded by antecedent ethanol in the hopes that this will stimulate investigation of its underlying mechanisms. Understanding these signaling pathways may provide a mechanistic rationale for the development of novel treatment interventions that target both the microcirculatory and parenchymal sequelae to I/R, thereby maximizing the therapeutic potential of the protected phenotypes produced by pharmacologic preconditioning.

Traditional Chinese Medicine improves dysfunction of peroxisome proliferator-activated receptor alpha and microsomal triglyceride transfer protein on abnormalities in lipid metabolism in ethanol-fed rats

We report the effects of Traditional Chinese Medicine (TCM) on alcohol-induced fatty liver in rats. TCM consists of Astragalus membranaceus, Morus alba, Crataegus pinnatifida, Alisma oriental, Salvia miltiorrhiza and Pueraria lobata. The rats were separated randomly into five groups; the CD group (n=10), which was fed a control diet for 10 weeks, the ED group (n=10), which was fed an isocaloric liquid diet containing ethanol for 10 weeks and given daily oral doses of TCM (0.222 g/kg/day; TCM222, 0.667 g/kg/day; TCM667, and 2.000 g/kg/day; TCM2000, n=10, respectively) over the last four weeks of the study. The ED group developed fatty livers, as determined by their lipid profiles and liver histological findings. Compared with the control group, liver/body weight, plasma triglyceride (TG) and total cholesterol (TC), liver TG and TC, plasma alanine aminotransferase (ALT) and aspartic aminotransferase (AST) significantly increased in the ED group. Also, free fatty acids (FFA) levels increased in both plasma and liver during the administration of ethanol. On the other hand, when rats were administrated with TCM, their liver/body weight, plasma TG, TC and FFA, liver TG, TC and FFA, plasma ALT and AST decreased significantly and the degree of hepatic lipid droplets was markedly improved compared with those in the ED group. Proper function of the peroxisome proliferator-activated receptor alpha (PPARalpha) is essential for the regulation of hepatic fatty acid metabolism. Microsomal triglyceride transfer protein (MTP) is essential for the secretion of triglycerides from the liver. mRNAs for PPARalpha and MTP were reduced in the livers of ethanol-fed rats. TCM restored the mRNA levels of PPARalpha and MTP, and prevented development of fatty livers in ethanol-fed rats. Impairment of PPARalpha and MTP function during ethanol consumption contributes to the development of alcohol-induced fatty liver, which can be overcome by TCM.

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.

Drug treatment of combined hyperlipidemia

Combined hyperlipidemia is increasing in frequency and is the most common lipid disorder associated with obesity, insulin resistance and diabetes mellitus. It is associated with other features of the metabolic syndrome including hypertension, hyperuricemia, hyperinsulinemia and highly atherogenic subfractions of lipoprotein remnant particles including small dense low density lipoprotein-cholesterol. This review examines the mechanisms by which combined hyperlipidemia arises and the various drugs including fibric acid derivatives, hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, and nicotinic acid which can be used either as monotherapy or in combination to manage it and to improve prognosis from atherosclerotic disease in diabetes mellitus, insulin resistant states and primary combined hyperlipidemia. The therapeutic approach to combined hyperlipidemia involves determination of whether the cause is hepatocyte damage or metabolic derangements. Combined hyperlipidemia due to hepatocyte damage should be treated by attention to the primary cause. In the case of metabolic dysfunction because of imbalance in glucose and fat metabolism, therapy of diabetes mellitus and obesity should be optimised prior to commencement of lipid lowering drugs. Both fibric acid derivatives and HMG-CoA reductase inhibitors can be used in the treatment of combined hyperlipidemia with fibric acid derivatives having greater effects on triglycerides and HMG-CoA reductase inhibitors on LDL-C though both have effects on the other cardiovascular risk factors. There is some evidence of benefit with both interventions in mild combined hyperlipidemias and large scale trials are underway. Fibric acid derivatives and HMG-CoA reductase inhibitor therapy can be combined with care, provided that gemfibrozil is avoided, fibric acid derivatives are given in the mornings and shorter half -life HMG-CoA reductase inhibitors are used at night. Combined hyperlipidemia emergencies occur with predominant hypertriglyceridemia in pregnancy or as a cause of pancreatitis. Therapy in the former should aim to reduce chylomicron production by a low fat diet and intervention to suppress VLDL-C secretion using omega-3 fatty acids. In the latter case, fluid therapy alone and medium chain plasma triglyceride infusions usually reduce levels satisfactorily though apheresis may be required. Blood glucose levels also need aggressive management in these conditions. Combined hyperlipidemia is likely to become an increasing problem with the increase in the prevalence of obesity and diabetes mellitus and needs aggressive management to reduce cardiovascular risk.

Effects of ethanol and haloperidol on plasma levels of hepatic enzymes, lipid profile, and apolipoprotein in rats

This work studied the effects of ethanol in the absence and presence of haloperidol under two experimental conditions. In protocol 1, rats were treated daily with ethanol (4 g/kg, p.o.) for 7 days, and received only haloperidol (1 mg/kg, i.p.) from the 8th day to the 14th day. In protocol 2, animals received ethanol, and the treatment continued with ethanol and haloperidol from the 8th day to the 14th day. Results show increases in alanine transaminase (ALT; 48% and 55%) and aspartate transaminase (AST; 32% and 22%) levels after ethanol or haloperidol (14 days) treatments, as compared with controls. Apolipoprotein A-1 (APO A1) levels were increased by haloperidol, after 7- (148%) but not after 14-day treatments, as compared with controls. Levels of lipoprotein (high-density lipoprotein (HDL-C)) tended to be increased only by ethanol treatment for 14 days. ALT (80%) and AST (43%) levels were increased in the haloperidol plus ethanol group (protocol 2), as compared with controls. However, an increase in APO A1 levels was observed in the haloperidol group pretreated with ethanol (protocol 1), as compared with controls and ethanol 7-day treatments. Triglyceride (TG) levels were increased in the combination of ethanol and haloperidol in protocol 1 (234%) and 2 (106%), as compared with controls. Except for a small decrease in haloperidol groups, with or without ethanol, as related to ethanol alone, no other effect was observed in HDL-C levels. In conclusion, we showed that haloperidol might be effective in moderating lipid alterations caused by chronic alcohol intake.Key words: ethanol, haloperidol, hepatic enzymes, lipid profiles.

Modification of the mitochondrial proteome in response to the stress of ethanol-dependent hepatotoxicity

Mitochondria are particularly susceptible to increased formation of reactive oxygen and nitrogen species in the cell that can occur in response to pathological and xenobiotic stimuli. Proteomics can give insights into both mechanism of pathology and adaptation to stress. Herein we report the use of proteomics to evaluate alterations in the levels of mitochondrial proteins following chronic ethanol exposure in an animal model. Forty-three proteins showed differential expression, 13 increased and 30 decreased, as a consequence of chronic ethanol. Of these proteins, 25 were not previously known to be affected by chronic ethanol emphasizing the power of proteomic approaches in revealing global responses to stress. Both nuclear and mitochondrially encoded gene products of the oxidative phosphorylation complexes in mitochondria from ethanol-fed rats were decreased suggesting an assembly defect in this integrated metabolic pathway. Moreover mtDNA damage was increased by ethanol demonstrating that the effects of ethanol consumption extend beyond the proteome to encompass mtDNA. Taken together, we have demonstrated that chronic ethanol consumption extends to a modification of the mitochondrial proteome far broader than realized previously. These data also suggest that the response of mitochondria to stress may not involve non-discriminate changes in the proteome but is restricted to those metabolic pathways that have a direct role in a specific pathology.

Acamprosate involvement in triacylglycerol hydrolysis and transacylation with cholesterol in chronically ethanol-drinking rats

Acamprosate (AC) is used as a drug for treating alcoholism. We evaluated the effect of AC on serum triacylglycerol hydrolysis (GEH, glycerol ester hydrolysis), triacylglycerol transacylation with cholesterol (GECAT, glycerol ester:cholesterol acyltransferase), and acylcholesterol hydrolysis (Cease, cholesterol ester hydrolysis) in an experimental model of alcoholism. Ethanol-preferring (PRF), non-preferring (NPF), and control (CR) male Wistar rats were treated with AC (500 mg/kg, p.o.) for 21 consecutive days. The beneficial effect of AC on lipid parameters of PRF rats included decreased triacylglycerol, total cholesterol, and LDL-cholesterol, and increased HDL-cholesterol levels. Acamprosate-compensated changes associated with ethanol consumption were observed. Acamprosate treatment decreased GECAT and increased Cease control rats, but increased GECAT and decreased CEase in PRF animals. In all groups of rats, AC treatment did not influence GEH. In conclusion, our results suggest that AC can influence triacylglycerol metabolism by its action on the balance between hydrolysis and transacylation in rats.

Alcohol and hepatitis C virus core protein additively increase lipid peroxidation and synergistically trigger hepatic cytokine expression in a transgenic mouse model

BACKGROUND/AIMS

Alcohol consumption accelerates the appearance of liver fibrosis and hepatocellular carcinoma in patients with chronic hepatitis C virus (HCV) infection, but the mechanisms of these interactions are unknown. We therefore investigated the effects of chronic ethanol consumption in HCV core protein-expressing transgenic mice.

METHODS

Ethanol was progressively added (up to 20%) to the drinking water that was given ad libidum.

RESULTS

In vivo fatty acid oxidation was not inhibited by ethanol consumption and/or HCV core expression. Both chronic ethanol consumption and HCV core expression decreased hepatic lipoprotein secretion and caused steatosis, but had no additive effects on lipoprotein secretion or steatosis. However, chronic ethanol consumption and HCV core protein additively increased lipid peroxidation and acted synergistically to increase the hepatic expression of transforming growth factor-beta (TGF-beta) and, to a less extent, tumor necrosis factor-alpha (TNF-alpha).

CONCLUSIONS

HCV core protein expression and chronic alcohol consumption have no effects on in vivo fatty acid oxidation and do not additively impair hepatic lipoprotein secretion, but additively increase hepatic lipid peroxidation and synergistically increase hepatic TNF-alpha and TGF-beta expression. These effects may be involved in the activation of fibrogenesis and the development of hepatocellular carcinoma in patients cumulating alcohol abuse and HCV infection.

The relationship of average volume of alcohol consumption and patterns of drinking to burden of disease: an overview

AIMS

As part of a larger study to estimate the global burden of disease attributable to alcohol: to quantify the relationships between average volume of alcohol consumption, patterns of drinking and disease and injury outcomes, and to combine exposure and risk estimates to determine regional and global alcohol-attributable fractions (AAFs) for major disease and injury categories. DESIGN, METHODS, SETTING: Systematic literature reviews were used to select diseases related to alcohol consumption. Meta-analyses of the relationship between alcohol consumption and disease and multi-level analyses of aggregate data to fill alcohol-disease relationships not currently covered by individual-level data were used to determine the risk relationships between alcohol and disease. AAFs were estimated as a function of prevalence of exposure and relative risk, or from combining the aggregate multi-level analyses with prevalence data.

FINDINGS

Average volume of alcohol consumption was found to increase risk for the following major chronic diseases: mouth and oropharyngeal cancer; oesophageal cancer; liver cancer; breast cancer; unipolar major depression; epilepsy; alcohol use disorders; hypertensive disease; hemorrhagic stroke; and cirrhosis of the liver. Coronary heart disease (CHD), unintentional and intentional injuries were found to depend on patterns of drinking in addition to average volume of alcohol consumption. Most effects of alcohol on disease were detrimental, but for certain patterns of drinking, a beneficial influence on CHD, stroke and diabetes mellitus was observed.

CONCLUSIONS

Alcohol is related to many major disease outcomes, mainly in a detrimental fashion. While average volume of consumption was related to all disease and injury categories under consideration, pattern of drinking was found to be an additional influencing factor for CHD and injury. The influence of patterns of drinking may be underestimated because pattern measures have not been included in many epidemiologic studies. Generalizability of the results is limited by methodological problems of the underlying studies used in the present analyses. Future studies need to address these methodological issues in order to obtain more accurate risk estimates.

Differential channelling of liver lipids in relation to susceptibility to hepatic steatosis in two species of ducks

In the human, hepatic steatosis can be associated with an imbalance between synthesis, secretion and storage of hepatic lipids, and exhibits a genetic susceptibility. The effect of overfeeding on hepatic lipid channelling was investigated in two genotypes of ducks that differ in their susceptibility to fatty liver, i.e. the common duck, Anas platyrhynchos, and the Muscovy duck, Cairina moschata. Before overfeeeding, the Muscovy duck exhibited a lower subcutaneous adiposity and a higher muscular development, whereas hepatic composition was similar in both genotypes (>5% lipids and triglycerides accounting for 6-10% lipids). In the plasma lipoprotein profile, HDL predominated (5.5-7.8 g/l) over VLDL (0.09-0.25 g/l) and LDL (0.65-1.06 g/l). All lipid and lipoprotein concentrations were lower in the Muscovy duck. In response to overfeeding, the Muscovy duck exhibited a higher degree of hepatic steatosis (62 vs. 50% lipids), and a lower increase in adiposity and in the concentration of plasma triglycerides (6-fold vs. 10-fold) and VLDL (23-fold vs. 34-fold). Thus, certain genotypes may be more responsive to the dietary induction of fatty liver because of a less efficient channelling of hepatic lipids towards secretion into plasma and adipose storage, and the duck may represent a suitable model in which to study the development of hepatic steatosis and its pathogenesis.

Peroxisome proliferator-activated receptor alpha (PPARalpha) agonist treatment reverses PPARalpha dysfunction and abnormalities in hepatic lipid metabolism in ethanol-fed mice

Proper function of the peroxisome proliferator-activated receptor alpha (PPARalpha) is essential for the regulation of hepatic fatty acid metabolism. Fatty acid levels are increased in liver during the metabolism of ethanol and should activate PPARalpha. However, recent in vitro data showed that ethanol metabolism inhibited the function of PPARalpha. We now report that ethanol feeding impairs fatty acid catabolism in the liver in part via blocking PPARalpha-mediated responses in C57BL/6J mice. Ethanol feeding decreased PPARalpha/retinoid X receptor alpha binding in electrophoretic mobility shift assay of liver nuclear extracts. mRNAs for PPAR-regulated genes were reduced (long chain and medium chain acyl-CoA dehydrogenases) or failed to be induced (acyl-CoA oxidase, liver carnitine palmitoyl-CoA transferase, very long chain acyl-CoA synthetase, very long chain acyl-CoA dehydrogenase) in livers of the ethanol-fed animals, and ethanol feeding did not increase the rate of fatty acid beta-oxidation. Wy14,643, a PPARalpha agonist, restored the DNA binding activity of PPARalpha/retinoid X receptor alpha, induced mRNA levels of PPARalpha target genes, stimulated the rate of fatty acid beta-oxidation, and prevented fatty liver in ethanol-fed animals. Impairment of PPARalpha function during ethanol consumption contributes to the development of alcoholic fatty liver, which can be overcome by Wy14,643.

Effect of alcohol on lipids and lipoproteins in relation to atherosclerosis

Several studies indicate that light-to-moderate alcohol consumption is associated with a low prevalence of coronary heart disease. An increase in high-density lipoprotein (HDL) cholesterol is associated with alcohol intake and appears to account for approximately half of alcohol's cardioprotective effect. In addition to changes in the concentration and composition of lipoproteins, alcohol consumption may alter the activities of plasma proteins and enzymes involved in lipoprotein metabolism: cholesteryl ester transfer protein, phospholipid transfer protein, lecithin:cholesterol acyltransferase, lipoprotein lipase, hepatic lipase, paraoxonase-1 and phospholipases. Alcohol intake also results in modifications of lipoprotein particles: low sialic acid content in apolipoprotein components of lipoprotein particles (e.g., HDL apo E and apo J) and acetaldehyde modification of apolipoproteins. In addition, "abnormal" lipids, phosphatidylethanol, and fatty acid ethyl esters formed in the presence of ethanol are associated with lipoproteins in plasma. The effects of lipoproteins on the vascular wall cells (endothelial cells, smooth muscle cells, and monocyte/macrophages) may be modulated by ethanol and the alterations further enhanced by modified lipids. The present review discusses the effects of alcohol on lipoproteins in cholesterol transport, as well as the novel effects of lipoproteins on vascular wall cells.

Resistance of HepG2 cells against the adverse effects of ethanol related to neutral lipid and phospholipid metabolism

The influence of both short- and long-term ethanol exposure on the lipid metabolism was determined in the human hepatoma cell line HepG2. Ethanol did not cause any cytotoxicity or lipid peroxidation even after 7 days of 100 mM ethanol treatment of HepG2 cells. Incubation of cells in the presence of [1-(14)C]ethanol demonstrated that these cells actively metabolize ethanol to acetyl CoA, incorporating the radioactive label into neutral lipids and phospholipids. [1,2,3-(3)H]glycerol was efficiently used in phospholipid and neutral lipid biosynthesis, showing higher radioactivity in phosphatidylcholine, phosphatidylethanolamine and triacylglycerols. Exposure of HepG2 cells to 100 mM ethanol for 24 hr did not significantly modify the incorporation of glycerol into newly synthesized phospholipids and neutral lipids, nor was lipid degradation affected by the presence of ethanol. When the alcohol treatment was prolonged for 7 days, incorporation of [1,2,3-(3)H]glycerol into triacylglycerols and diacylglycerols showed a slight increase concomitantly with decreased radioactivity in the major phospholipids, phosphatidylcholine and phosphatidylethanolamine. In addition, these changes were associated with a greater release of radiolabeled triacylglycerols into the culture medium. These results indicate that ethanol does not cause in HepG2 cells the marked lipogenic stimulation widely shown in hepatocytes, and demonstrate that HepG2 cells strongly resist the adverse effects of ethanol. Since these cells lack the isoenzymatic form of cytochrome P(450) mainly involved in the ethanol metabolism (namely cytochrome P(450)2E1) and also are devoid of alcohol dehydrogenase activity, we propose that the toxic actions of ethanol on liver must be linked to the activity of one or both of these systems.

Comparative study of the effects of short- and long-term ethanol treatment and alcohol withdrawal on phospholipid biosynthesis in rat hepatocytes

This study describes the effects of short- and long-term ethanol treatment and withdrawal on the biosynthesis of the phospholipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in hepatocytes isolated from rats, using isotopically labelled choline and ethanolamine as exogenous precursors. Our results demonstrate that short-term ethanol consumption increases the incorporation of exogenous polar bases into PC and PE, whereas long-term ethanol administration provokes a differential effect in both PC and PE biosynthesis via cytidine diphosphate derivatives (CDP-derivatives), decreasing PC synthesis and increasing the biosynthesis of PE. We suggest that the increased biosynthesis of PE after ethanol treatment results from changes in lipogenic substrates produced as a consequence of ethanol metabolism, whilst the specific inhibition of PC biosynthesis seems to be a consequence of alterations of enzymes involved in the CDP-choline pathway. With regard to the influence of ethanol on PE methylation to give PC, our results demonstrate that ethanol activates this pathway in short-term, as well as chronic ethanol treatment. Ethanol withdrawal returns the activity of the PC and PE pathways to control levels. The alterations in the biosynthesis of the main phospholipids, PC and PE, demonstrated in this study could be of a great physiological interest in determining the pathology of alcoholism.

Decreased microsomal triglyceride transfer protein activity contributes to initiation of alcoholic liver steatosis in rats

BACKGROUND/AIMS

To elucidate the role of microsomal triglyceride transfer protein (MTP) in the pathogenesis of alcoholic fatty liver, the effects of ethanol on MTP activity and gene expression were investigated.

METHODS AND RESULTS

Male Sprague-Dawley rats fed an ethanol-containing liquid diet for 37 days, respectively, showed 2.9- and 4.9-fold increases in hepatic cholesterol and triglyceride content in comparison with rats fed an isocaloric ethanol-free diet (P<0.01). Furthermore, a significant decrease in MTP activity and mRNA expression (by 27 and 58%, respectively) was observed after ethanol administration. Intravenous injection of human recombinant hepatocyte growth factor (hrHGF) on each of the last 7 days markedly suppressed ethanol-induced lipid accumulation in the liver. This inhibition of fatty change by hrHGF was accompanied by recovery of MTP activity and gene expression. No inhibitory effect of hrHGF on ethanol-induced acyl-CoA synthetase activation was observed. Experiments using human hepatoma-derived HepG2 cells indicated a direct positive effect of hrHGF on MTP gene expression as well as apolipoprotein B secretion.

CONCLUSIONS

These results suggest that reduced MTP activity is crucial to development of alcoholic fatty liver, while promotion of MTP activity by HGF might serve as a therapeutic measure against alcoholic liver steatosis.

Short-term treatment with alcohols causes hepatic steatosis and enhances acetaminophen hepatotoxicity in Cyp2e1(-/-) mice

CYP2E1 has been reported to have an essential role in alcohol-mediated increases in hepatic steatosis and acetaminophen hepatotoxicity. We found that pretreatment of Cyp2e1(-/-) mice with ethanol plus isopentanol, the predominant alcohols in alcoholic beverages, for 7 days resulted in micro- and macrovesicular steatosis in the livers of all mice, as well as a dramatic increase in acetaminophen hepatotoxicity. In Cyp2e1(-/-) mice administered up to 600 mg acetaminophen/kg alone and euthanized 7 h later, there was no increase in serum levels of ALT. In Cyp2e1(-/-) mice pretreated with ethanol and isopentanol, subsequent exposure to 400 or 600 mg acetaminophen/kg resulted in centrilobular necrosis in all mice with maximal elevation in serum levels of ALT. Acetaminophen-mediated liver damage was similar in males and females. Hepatic microsomal levels of APAP activation in untreated females were similar to those in males treated with the alcohols. However, the females, like the males, required pretreatment with the alcohols in order to increase APAP hepatotoxicity. These findings suggest that, in the Cyp2e1(-/-) mice, the alcohol-mediated increase in acetaminophen hepatotoxicity involves the contribution of other factors, in addition to induction of CYP(s) that activate acetaminophen. Alternatively, CYP-mediated activation of acetaminophen measured in vitro may not reflect the actual activity in vivo. Our findings that a 7-day treatment with ethanol and isopentanol causes extensive hepatic steatosis and increases acetaminophen hepatotoxicity in Cyp2e(-/-) mice indicate that CYP2E1 is not essential for either response.

Metabolic complications of obesity

The rising prevalence of obesity is accompanied by an increasing number of patients with the metabolic complications of obesity. The major complications come under the heading of the metabolic syndrome. This syndrome is characterized by plasma lipid disorders (atherogenic dyslipidemia), raised blood pressure, elevated plasma glucose, and a prothrombotic state. The clinical consequences of the metabolic syndrome are coronary heart disease and stroke, type 2 diabetes and its complications, fatty liver, cholesterol gallstones, and possibly some forms of cancer. At the heart of the metabolic syndrome is insulin resistance, which represents a generalized derangement in metabolic processes. Obesity is the predominant factor leading to insulin resistance, although other factors play a role. The mechanistic link between insulin resistance and the metabolic syndrome is complex. The relationship is modulated by yet other factors, such as physical activity, body fat distribution, hormones, and a person's genetic polymorphic architecture. A better understanding of the molecular basis of this relationship is needed to suggest new targets for prevention and treatment of the complications of obesity. In addition, understanding at the clinical level will lead to improved management of these complications.

Serum triglycerides, the liver and the pancreas

Massive hypertriglyceridaemia associated with fatty liver and abdominal pain or frank pancreatitis (the chylomicronaemia syndrome) is uncommon, but clinically important and under-recognized. It may arise as a result of severe genetic defects in lipolysis or, more commonly, from a moderate primary hypertriglyceridaemia that is exacerbated by a secondary cause. The latter include several drugs, among which the protease inhibitors, used for the treatment of human immunodeficiency virus infection, are increasingly apparent. In the acute situation plasma exchange, fat-free parenteral nutrition and acute insulin treatment, even in nondiabetic persons, may be valuable. A potentially major advance in prophylaxis is the use of high-dose antioxidant therapy, which has been shown to reduce attacks of pancreatitis even in the absence of a reduction in serum triglycerides. Asymptomatic patients with abnormal liver function tests are common in the lipid clinic, and can be a difficult group in which to make management decisions. Among those who are not taking excessive amounts of alcohol, many will have nonalcoholic steatohepatitis. The care of these patients is discussed, but there remains considerable uncertainty regarding their optimum management and prognosis.