Biochemical and molecular basis of alcohol-induced injury to liver and other tissues

Starvation impairs antioxidant defense in fatty livers of rats fed a choline-deficient diet

Although fatty liver (FL) is considered an innocuous condition, the frequent incidence of graft failure when FL are transplanted has renewed interest in the intracellular disorders causative of or consequent to fatty degeneration. Oxidative stress and nutritional status modulate the tolerance to reperfusion injury in control livers (CL), but very little is known in the case of FL. This study was designed to compare the oxidative balance in CL and FL from fed and food-deprived rats. Serum and liver samples were collected from fed and starved (18 h) rats with CL or FL induced by a choline-deficient diet. Hepatic injury was assessed by transaminase activities and histology. The hepatic concentrations of glutathione (GSH), vitamin C, alpha-tocopherol, thiobarbituric acid-reactive substances (TBARS) and protein carbonyls (PC) were measured. Fed rats with FL had significantly greater TBARS and lower alpha-tocopherol and vitamin C levels than those with CL, whereas GSH and PC concentrations were not affected. Starvation impaired the oxidative balance in both groups. However, compared with the other groups, FL from food-deprived rats generally had the lowest hepatic concentrations of alpha-tocopherol, vitamin C and GSH. Unlike in CL, protein oxidation occurred in FL. These data indicate that fatty liver induced by consumption of a choline-deficient diet is associated with a lower level of antioxidants, which results in lipid peroxidation. Starvation further affects these alterations and extends the damage to proteins. In conclusion, steatosis and starvation may act synergistically on the depletion of antioxidants, predisposing fatty livers to a reduced tolerance to oxidative injury.

The alcohol-inducible form of cytochrome P450 (CYP 2E1): role in toxicology and regulation of expression

Cytochrome P450 (CYP) 2E1 catalyzes the metabolism of a wide variety of therapeutic agents, procarcinogens, and low molecular weight solvents. CYP2E1-catalyzed metabolism may cause toxicity or DNA damage through the production of toxic metabolites, oxygen radicals, and lipid peroxidation. CYP2E1 also plays a role in the metabolism of endogenous compounds including fatty acids and ketone bodies. The regulation of CYP2E1 expression is complex, and involves transcriptional, post-transcriptional, translational, and post-translational mechanisms. CYP2E1 is transcriptionally activated in the first few hours after birth. Xenobiotic inducers elevate CYP2E1 protein levels through both increased translational efficiency and stabilization of the protein from degradation, which appears to occur primarily through ubiquitination and proteasomal degradation. CYP2E1 mRNA and protein levels are altered in response to pathophysiologic conditions by hormones including insulin, glucagon, growth hormone, and leptin, and growth factors including epidermal growth factor and hepatocyte growth factor, providing evidence that CYP2E1 expression is under tight homeostatic control.

Risk factors for alcoholic liver disease

Abstract Alcoholic liver disease (ALD) is still a frequent disorder, even though its incidence appears to be decreasing. In spite of intense investigation, the precise mechanisms leading to ALD are still imprecisely known. This is due in part to the lack of a reliable animal model; in part to the difficulty of obtaining clinical data of adequate sample size and derived from unblased populations and finally from the lack of uniformity of the criteria used to define ALD. This paper will review what is known of the various pieces of this puzzle, with particular emphasis not only on the total amount of alcohol consumed, but also on drinking patterns and type of alcoholic beverage ingested. The other potential factors such as age, gender, genetic background, nutritional status, occupational hazards and viral diseases (especially HCV infection) will be touched upon.

Ethanol alters angiotensin II stimulated mitogen activated protein kinase in hepatocytes: agonist selectivity and ethanol metabolic independence

Angiotensin II activated mitogen-activated protein kinase (MAPK) (p42 and p44) in rat hepatocytes exposed to ethanol and the relevance of ethanol metabolism on this activation was investigated. Hepatocytes, isolated from rat liver, were treated with or without ethanol for 24 h. Angiotensin II, vasopressin, insulin, serum and epinephrine significantly increased hepatocyte MAPK activity. Platelet activating factor (PAF), tumor necrosis factor-alpha (TNF-alpha), and insulin-like growth factor-1 (IGF-1) had little effect on MAPK activation. Interestingly, among the above agonists, which activated hepatocyte MAPK, ethanol exposure potentiated only angiotensin II and epinephrine-stimulated MAPK. Thus, potentiation of MAPK by ethanol exhibited agonist selectivity. In contrast to several other cells, there was prevalence of p42 over p44 MAPK band in hepatocytes. Angiotensin II treatment caused a rapid activation (peak 5 min) of MAPK followed by a decrease to basal levels in 30 min. Exposure with 100 mM ethanol potentiated the angiotensin II stimulated MAPK activity. This potentiation was partially blocked by pertussis toxin suggesting it to be a G-protein-dependent event. Treatment of the hepatocytes with pyrazole (an inhibitor of ethanol metabolism) or acetaldehyde (an ethanol metabolite) had no effect on potentiation. Thus, ethanol potentiation of hepatocyte MAPK is agonist-selective and independent of ethanol metabolism.

Cytochrome P450 2E1: its clinical and toxicological role

Cytochrome (CYP) P450 2E1 is clinically and toxicologically important and it is constitutively expressed in the liver and many other tissues. In contrast to many other CYP isoenzymes, indisputable evidence for a functionally important polymorphism of CYP2E1 in the human population is lacking. CYP2E1 metabolizes a wide variety of chemicals with different structures, in particular small and hydrophobic compounds, including potential cytotoxic and carcinogenic agents. In addition, chlorzoxazone and trimethadione metabolism are good CYP2E1 probes for liver disease in vivo and in vitro. In the future, methods for fully analysing the function of CYP2E1 using knockout mice will be established. This article reviews recent advances in our understanding of the role of human CYP2E1 in drug metabolism.

Enhanced urinary excretion of cysteinyl leukotrienes in patients with acute alcohol intoxication

BACKGROUND & AIMS

Leukotrienes are proinflammatory mediators. Ethanol inhibits the catabolism of both cysteinyl leukotrienes (leukotriene E(4) [LTE(4)] and N-acetyl-LTE(4)) and leukotriene B(4) (LTB(4)) in hepatocytes. We examined the metabolic derangement of leukotriene inactivation by ethanol in humans in vivo.

METHODS

LTE(4), N-acetyl-LTE(4), LTB(4), and 20-hydroxy-LTB(4) were quantified in urine samples from 16 patients with acute alcohol intoxication (mean blood ethanol, 75 mmol/L). In 9 healthy volunteers, urinary LTE(4) was determined before and after ethanol consumption (mean blood ethanol, 14 mmol/L).

RESULTS

The excretion of LTE(4) during alcohol intoxication was 286 compared with 36 nmol/mol creatinine in healthy subjects (P < 0.01); the corresponding values for N-acetyl-LTE(4) were 101 and 11 nmol/mol creatinine, respectively (P < 0.001). This excretion of cysteinyl leukotrienes decreased when the blood ethanol concentration returned to normal. LTB(4) and 20-hydroxy-LTB(4) were detectable only in patients with excessive blood ethanol concentrations (mean, 95 mmol/L). In healthy volunteers, LTE(4) excretion increased 3-5 hours after ethanol consumption (mean peak concentration of 1.5 nmol/L compared with 0.5 nmol/L for basal values; P < 0.005).

CONCLUSIONS

Ethanol at high concentration induces increased leukotriene excretion into urine. These changes are consistent with inhibition of leukotriene catabolism and inactivation induced by ethanol, as well as with a higher leukotriene formation caused by ethanol-induced endotoxemia.

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.

The effects of chronic alcohol abuse on pulmonary glutathione homeostasis

The incidence and severity of the acute respiratory distress syndrome (ARDS) is increased in critically ill patients with a prior history of chronic alcohol abuse; however, the specific mechanisms responsible for this association are unknown. Recently, we determined that chronic ethanol ingestion in rats decreased the alveolar epithelial lining fluid (ELF) concentration of the antioxidant glutathione (GSH), which is a characteristic finding in patients with ARDS. However, the effects of chronic alcohol abuse on the human alveolar epithelium are essentially unknown. Therefore, as a first step we asked if chronic alcohol abuse, independent of other comorbid conditions, decreases the concentration of GSH in the human lung. We determined that otherwise healthy chronic alcoholics had significantly decreased ELF concentrations of GSH compared with nonalcoholic control subjects (79 micromol [48 to 118 micromol] versus 576 micromol [493 to 728 mmol], p < 0.001). Furthermore, the percentage of GSH in the oxidized form was higher in the chronic alcoholics (9.8% [2.2 to 14.8%] versus 2.8% [0.4 to 4.0%] p = 0.05), indicative of increased utilization of GSH. This is the first report that chronic alcohol abuse alters GSH homeostasis in the human lung, and suggests a potential mechanism by which chronic alcohol abuse predisposes susceptible patients to develop ARDS.

Nonsynergic effect of ethanol and lead on heme metabolism in rats

The heme biosynthetic pathway is a metabolic target of alcohol and lead poisoning. To analyze the interdependence of both xenobiotics on porphyrin metabolism, male Wistar rats (n=47) were divided into four groups and were fed Lieber-DeCarli semiliquid control or alcoholic diets containing or not containing lead acetate (160 mg/liter) for 8 weeks. After this period, hematocrit values and porphyrin concentration in liver and urine were similar in all groups, indicating that the goal of inducing only mild chronic intoxication was achieved. Compared with the control group, rats poisoned only with lead exhibited high levels of this metal in blood and liver, increased erythrocytic protoporphyrin, and hypoactivity of aminolevulinate dehydrase (ALA-D) in both blood and liver. Rats intoxicated only with alcohol exhibited mild hypoactivity of both hepatic and erythrocytic ALA-D, although such decreased enzymatic values did not achieve statistical significance. Rats receiving ethanol and lead simultaneously demonstrated abnormalities in heme biosynthesis similar to those in rats exposed to lead, although zinc hepatic levels decreased significantly only in animals exposed to both xenobiotics. Hepatic GSH and urinary ALA and porphyrin levels were maintained in a similar range in all groups.

Effects of ethanol and diabetes on galactose oxidative metabolism and elimination in rats

Blood galactose clearance after an intravenous galactose load has been widely used for years as an index of liver function. We developed a noninvasive [13C]galactose breath test, which explores galactose oxidative metabolism; this test is well correlated with liver fibrosis in patients with chronic viral hepatitis. The goal of this study was to evaluate the influence of nonhepatic factors such as diabetes and ethanol on whole-body galactose clearance (measured as the serum galactose elimination capacity test) and oxidative metabolism (measured as the [13C]galactose-induced breath13CO2production) in rats. Acute ethanol administration induced a significant decrease of galactose clearance and13CO2production. There was a significant correlation between the amount of ethanol given and the inhibition of galactose metabolism (R2= 0.72, p < 0.0001). In streptozotocin-induced diabetic rats, the [13C]galactose-induced breath13CO2production was significantly reduced (p < 0.0001) and normalized by insulin treatment. However, diabetes did not decrease whole-body galactose clearance, indicating an isotopic dilution of [13C]glucose produced from [13C]galactose metabolism into the enlarged glucose pool. These results must be taken into account when using the [13C]galactose breath test as a quantitative liver function test.Key words: stable isotopes, carbon 13, liver functions, breath tests.

Polaprezinc protects gastric mucosal cells from noxious agents through antioxidant properties in vitro

BACKGROUND

Polaprezinc has been shown to exert an anti-oxidant property in a tube experiment, protect gastric mucosa from experimental ulcerations in vivo, and accelerate the healing of gastric ulcer in humans.

AIM

To examine a possible protective effect of polaprezinc on oxidant-mediated injury in primary monolayer cultures of rat gastric fundic mucosa.

METHODS

Cytotoxicity was quantified by measuring 51Cr release. Whether or not polaprezinc exerts an antioxidant property was investigated by determining the effect of this agent on hydrogen peroxide (H2O2)-induced injury. The effects of polaprezinc on superoxide (O2-. ) generation as well as on ethanol (EtOH)-induced injury were also examined. Generation of O2-. was assessed by the reduction in cytochrome c.

RESULTS

H2O2 caused a time- and dose-dependent increase in 51Cr release. The dose-response curve of 51Cr release by H2O2 shifted to the right in the presence of polaprezinc. Polaprezinc, at submillimolar concentrations, prevented H2O2-induced 51Cr release. EtOH also caused a dose-dependent increase in 51Cr release, which was prevented by the addition of polaprezinc. The incubation of cells with EtOH caused an increase in cytochrome c reduction, as the concentrations of EtOH increased. Polaprezinc inhibited EtOH-induced cytochrome c reduction. Protection by polaprezinc was microscopically associated with the prevention of monolayer disruption.

CONCLUSIONS

Polaprezinc is antioxidative and directly protects gastric mucosal cells from noxious agents through its antioxidant properties in vitro. This finding may provide the theoretical basis for the usage of an antiulcer drug with antioxidant properties for the treatment of gastric inflammation, such as that induced by ethanol.

Enhanced Gi-protein-mediated mitogenesis following chronic ethanol exposure in a rat model of experimental hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is associated with increased expression and function of inhibitory guanine nucleotide regulatory proteins (Gi-proteins). This study addresses the effects of chronic ethanol exposure on the expression and function of adenylyl cyclase (AC)-linked G-proteins (Gs and Gi) and growth in experimental HCC. G-protein expression and function was determined by immunoblot in the hepatic tumorigenic H4IIE cell line and isolated cultured hepatocytes in the absence or presence of ethanol (5-100 mmol/L). Chronic exposure (24 hours) to ethanol dose-dependently increased Gialpha1/2 expression in the H4IIE cell line, but not in cultured hepatocytes. Gsalpha-protein expression remained unchanged in both H4IIE cells and cultured hepatocytes following ethanol treatment. In addition, ethanol directly activated a Gi-protein, because pertussis toxin (PTx)-catalyzed, adenosine diphosphate (ADP)-dependent ribosylation of Gialpha substrates decreased following ethanol treatment. The increased functional activity of Gialpha1/2-protein expression was confirmed by demonstrating that ethanol dose-dependently inhibited basal and stimulated AC activity in H4IIE cells, while not significantly altering basal AC activity in isolated cultured hepatocytes. Furthermore, while ethanol had no significant effect on basal mitogenesis in H4IIE cells or hepatocytes, increased mitogenesis caused by direct Gialpha-protein stimulation (mastoparan M7; 10-5,000 nmol/L) was further enhanced in the presence of ethanol, an effect that was completely blocked following Gi-protein inhibition (PTx; 100 ng/mL). In contrast, activation of Gi-proteins using M7 failed to alter cellular mitogenesis in isolated cultured hepatocytes, whether in the absence or presence of ethanol. Finally, analysis of mitogen-activated protein kinase (MAPK) activity demonstrated that chronic ethanol treatment further enhanced Gi-protein-stimulated MAPK activity in hepatic tumorigenic cells. In conclusion, these data demonstrate that ethanol enhances cellular mitogenesis in experimental HCC as a result of, at least in part, a Gi-MAPK-dependent pathway. Furthermore, this effect may be caused by ethanol's direct up-regulation of the expression and activity of Gi-proteins in HCC.

An allometric model for predicting blood ethanol elimination in mammals

The relationship of ethanol elimination kinetics in mammals was estimated using the allometric principle. The hypothesis of relationships between parameters obtained from the compartment model with Michaelis-Menten elimination kinetics and body weight can lead to common equations of blood ethanol elimination in mammals. The maximum elimination velocity (g/hr) and the apparent volume of distribution (L) were significantly proportional to the 0.71 and 0.93 powers of body weight (r = 0.994, P < 0.01 and r = 0.998, P < 0.001), respectively. There was no significant relationship between the Michaelis constant and body weight. In the differential equations of the two-compartment model, the kinetics parameters were substituted for the obtained power functions. Good fitting of these equations for the real data showed that ethanol elimination kinetics in mammals can be predicted quantitatively.

Peroxisomal and microsomal fatty acid oxidation in liver of rats after chronic ethanol consumption

1. Microsomal P450 and peroxisomal fatty acid oxidation activities were studied in liver of rats after long-term ethanol consumption. 2. Ethanol increased the microsomal lauric acid omega-hydroxylation and the aminopyrine N-demethylation catalyzed by cytochrome P450. 3. Ethanol increased peroxisomal beta-oxidation of palmitoyl CoA and catalase activity in liver. 4. Both microsomal and peroxisomal activities behaved in a coordinate way in the liver of rats with long-term ethanol consumption. 5. These results would support a role of microsomal omega-hydroxylation and peroxisomal beta-oxidation of fatty acids in an extramitochondrial pathway of lipid oxidation in the liver.

Dietary carbohydrate intake plays an important role in preventing alcoholic fatty liver in the rat

BACKGROUND/AIMS

Dietary carbohydrate intake during ethanol ingestion augments the induction of hepatic cytochrome P450 2E1 (CYP2E1) by ethanol. This study addresses the role of carbohydrate intake in the development of alcoholic fatty liver in the rat.

METHODS

Male Sprague-Dawley rats were pair-fed on liquid diets containing ethanol (3.5 g/day, 36% of total calories) with different amounts of carbohydrate and fat for 4 weeks, and the development of fatty liver was observed biochemically and morphologically.

RESULTS

An ethanol-containing low-carbohydrate diet (protein 17%; fat 36%; carbohydrate 11%; ethanol 36%) had more markedly adverse effects on the liver of rats than did an isocaloric ethanol-containing high-carbohydrate diet (protein 17%; fat 5%; carbohydrate 42%; ethanol 36%). The hepatic triglyceride level in the rats that consumed the low-carbohydrate diet was higher than that in the rats kept on the high-carbohydrate diet, a finding that was confirmed histologically. The ethanol-containing low-carbohydrate diet caused a marked increase in the activity of hepatic CYP2E1. The CYP2E1 protein level, as measured by Western blot analysis, matched the activity of CYP2E1, as measured by the rates of dimethylnitrosamine, p-nitrophenol and ethanol metabolism. The severity of the fatty liver was well correlated with the increased CYP2E1 activity.

CONCLUSIONS

Dietary carbohydrate intake plays an important role in the development of alcoholic fatty liver by affecting CYP2E1 activity in the liver. A liquid diet containing ethanol in which the ethanol is included at the expense of fat is more acceptable to rats than a diet in which the ethanol replaces carbohydrate.

Inhibition of CYP2E1 by chlormethiazole as measured by chlorzoxazone pharmacokinetics in patients with alcoholism and in healthy volunteers

BACKGROUND

Chlormethiazole has been shown in in vitro studies, with use of rat and human liver microsomes, to specifically inhibit cytochrome P4502E1 (CYP2E1)-mediated activity by inhibition of the rate of CYP2E1 gene transcription. It is known that CYP2E1 is involved in the activation of many low-molecular-weight toxins and carcinogens and may be involved in the development of alcohol-induced liver disease.

METHODS

The pharmacokinetics of a single oral dose of 250 mg chlorzoxazone, a marker of the activity of CYP2E1, were measured in five healthy drug-free volunteers and in 16 patients with alcoholism receiving 1.2 gm or 2.4 gm chlormethiazole per day for 1, 2, or 3 days. The patients were starting an alcohol-withdrawal program and were supposed to have an induced CYP2E1 activity.

RESULTS

The results suggest that chlormethiazole strongly decreased chlorzoxazone clearance in the patients with alcoholism compared with clearance in the control subjects (3.98 +/- 1.8 L/hr versus 12.7 +/- 5.6 L/hr; p < 0.005), prolonged the elimination half-life (3.91 +/- 1.23 hours versus 1.12 +/- 0.34 hours; p < 0.001), and caused a threefold increase in the area under the concentration versus time curve of chlorzoxazone (73.0 +/- 35.5 mg.hr/L versus 21.3 +/- 13.7 mg.hr/L; p < 0.005). They also suggest that chlormethiazole significantly decreased the area under the concentration versus time curve of the metabolite 6-hydroxy-chlorzoxazone (4.56 +/- 1.27 mg.hr/L versus 7.1 +/- 1.84 mg.hr/L; p < 0.05).

CONCLUSION

Chlormethiazole administration seems to result in a marked reduction of CYP2E1 activity in subjects with high CYP2E1 activity and could at least partially explain the claimed hepatoprotective action of this drug.

Ultrastructural study of the alterations in spinal ganglion cells of rats chronically fed on ethanol

A study was conducted to find the effects of chronic alcohol (EtOh) administration on the rat dorsal root ganglion (DRG) cells in vivo. Morphoquantitative changes of the cytoplasmic organelles in neurons and satellite cells (SC) of lumbar DRG of animals fed with 20 and 40% of EtOH for 6 months were determined at the electron microscopic level. Stereological methods were used to quantitatively evaluate the changes in the neuronal Golgi fields, in the lysosomal system components called dense bodies (DB), in the mitochondria, and in the cytoplasmic perikaryal projections (PP) characteristic of DRG neurons. Prolonged consumption of 20% EtOh was well tolerated by neurons. There were, however, some structural modifications in the studied organelles, and there was a significant increase in the neuronal surface. In SC the number of mitochondria and DB increased significantly. Treatment with 40% EtOH produced massive organelle alterations in both neurons and SC, including disruption of the PP, markedly reducing the neuronal surface area. The architecture of the SC sheath appeared disorganized. The alterations resembled those of senescence, and indicated that a high dose of EtOH (or its metabolites) had a profound disruptive effect on the organelles and on the membrane systems of the DRG cells. The SC of the DRG units from the animals fed with EtOH were the first to show significant morphological alterations. When the architecture of the SC sheath already showed evident signs of disorganization, the neuronal body was just beginning to show morphological damage. These results suggest that the progressive disorganization of the SC sheath is a probable source of complication in peripheral neuropathy.

Effects of chronic ethanol consumption on extramitochondrial fatty acid oxidation and ethanol metabolism by rat kidney

1. We evaluated the effects of chronic ethanol consumption on microsomal and peroxisomal fatty acid oxidation and on ethanol oxidation by the kidney. 2. When mature rats were fed 20% ethanol for 10 weeks, an increase in alcohol dehydrogenase and catalase activities were observed in the kidney. 3. Renal microsomal and peroxisomal oxidation of fatty acids also increased by the treatment, but total cytochrome P450 content did not. 4. We concluded that chronic ethanol consumption results in an increased extramitochondrial disposition of fatty acids and ethanol oxidation by the kidney.

Increased lipid peroxidation and impaired antioxidant enzyme function is associated with pathological liver injury in experimental alcoholic liver disease in rats fed diets high in corn oil and fish oil

Increased hepatic oxidative stress with ethanol administration is hypothesized to be caused either by enhanced pro-oxidant production or decreased levels of antioxidants or both. We used the intragastric feeding rat model to assess the relationship between hepatic antioxidant enzymes and pathological liver injury in animals fed different dietary fats. Male Wistar rats (5 per group) were fed ethanol with either medium-chain triglycerides (MCTE), palm oil (PE), corn oil (CE), or fish oil (FE). Control animals were fed isocaloric amounts of dextrose instead of ethanol with the same diets. The following were evaluated in each group: liver pathology, lipid peroxidation, manganese superoxide dismutase (MnSOD) levels, copper-zinc SOD (CuZnSOD) levels, glutathione peroxidase (GPX) levels, and catalase (CAT) levels. All enzymes were evaluated using activity assays and immunoblots. Rats fed FE showed the most severe pathology (fatty liver, necrosis, and inflammation), those fed CE showed moderate changes, those fed PE showed fatty liver only, and those fed MCTE were normal. Parameters indicative of lipid peroxidation (conjugated dienes and thiobarbituric acid-reactive substances) were also greater in rat livers from animals fed the diets high in polyunsaturated fatty acids (CE and FE). CuZnSOD, GPX, and CAT activities showed an inverse correlation (r=-.92, P < .01) with severity of pathological injury, with the lowest levels for both enzymes found in FE-fed rats. Decreased enzyme activity in CE- and FE-fed rats was accompanied by similar decreases in immunoreactive protein. Ethanol administration did not cause significant decreases in enzyme activity in groups that showed no necroinflammatory changes (MCTE and PE). MnSOD activity showed no significant change in any ethanol-fed group. Our results show that decreases in CuZnSOD, GPX, and CAT occur in rats showing pathological liver injury and also having the highest levels of lipid peroxidation. These results suggest that feeding dietary substrates that enhance lipid peroxidation can exacerbate both ethanol-induced oxidative damage as well as necroinflammatory changes. The decrease in activity of antioxidant enzymes observed in animals fed diets high in polyunsaturated fatty acids and ethanol could possibly increase the susceptibility to oxidative damage and further contribute to ethanol-induced liver injury.

Alcohol and the pancreas

Alcoholic pancreatitis is a major, often lethal complication of alcohol abuse. Until recently it was generally accepted that alcoholic pancreatitis was a chronic disease from the outset. However, there is now emerging evidence in favour of the necrosis-fibrosis hypothesis that alcoholic pancreatitis begins as an acute process and that repeated acute attacks lead to chronic pancreatitis, resulting in exocrine and endocrine failure. Over the past 10-15 years, the focus of research into the pathogenesis of alcoholic pancreatitis has shifted from possible sphincteric and ductular abnormalities to the acinar cell itself which has increasingly been implicated as the initial site of injury. Recent studies have shown that the acinar cell can metabolize alcohol at rates comparable to those observed in hepatocytes. In addition, it has been demonstrated that alcohol and its metabolites exert direct effects on the pancreatic acinar cell which may promote premature digestive enzyme activation and oxidant stress. The challenge remains to identify predisposing and triggering factors in this disease.

Serum activities of classes I and II alcohol dehydrogenases in toxic liver damage

The activities of classes I and II alcohol dehydrogenase isoenzymes were determined in the sera of patients with toxic hepatitis using class-specific fluorogenic substrates. The activities of total alcohol dehydrogenase and enzymes indicative of liver damage were also measured. We found a statistically significant increase of class I alcohol dehydrogenase isoenzymes. The increase in class I (two-fold) was similar to the increase of alkaline phosphatase. In a correlated study, we observed a good correlation of the activity of class II isoenzymes with alanine aminotransferase. The total alcohol dehydrogenase activity was enhanced and correlated with lactate dehydrogenase. These results demonstrated that the alcohol dehydrogenase and class I isoenzymes are indicatory enzymes of liver cell damage, and may be diagnostically useful in toxic hepatitis.

Effect of exercise training and chronic ethanol ingestion on cholinesterase activity and lipid peroxidation in blood and brain regions of rat

1. This study examines the effects of exercise training and chronic ethanol consumption on cholinesterase activity and its relationship to lipid peroxidation in blood and brain regions of rat. 2. Exercise training (6.5 weeks) decreased acetylcholinesterase (AChE) activity significantly (64% of control) in hypothalamus and increased AChE activity in cerebral cortex (149% of control), whereas, malondialdehyde (MDA) levels increased in hypothalamus (129% of control) and decreased in cortex, striatum, and cerebellum (50%, 69% and 75% of control), respectively. 3. Chronic ethanol ingestion (2.0 gm/kg, p.o. for 6.5 weeks) significantly increased butyrylcholinesterase (BuChE) activity in plasma (136% of control) and decreased AChE activity in hypothalamus (63% of control), whereas, MDA levels increased in hypothalamus, cortex, and plasma (140%, 130% and 220% of control), respectively. 4. The combination significantly increased BuChE activity (173% of control) in plasma and decreased AChE activity (71% of control) in hypothalamus and (57% of control) in cerebellum, whereas, MDA levels increased in hypothalamus, cerebellum, medulla and plasma (134%, 128%, 140% and 309% of control), respectively. 5. Exercise training, chronic ethanol ingestion, and combination selectively inhibited hypothalamic AChE and the inhibition was correlated with increased lipid peroxidation (r = 0.11, 0.41 and 0.45) which may perturb hypothalamic function. The combination enhanced the peripheral stress response by increasing plasma BuChE activity and lipid peroxidation.

Determination of chlorzoxazone and 6-hydroxychlorzoxazone in plasma by gas chromatography--mass spectrometry

A gas chromatographic-mass spectrometric method is presented which allows the determination of chlorzoxazone and 6-hydroxychlorzoxazone after derivatization with the reagent N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamide. No interference was observed from endogenous compounds following the extraction of plasma samples from six different human subjects. The standard curves were linear over a working range of 20 to 4000 ng/ml and of 20 to 1000 ng/ml for chlorzoxazone and 6-hydroxychlorzoxazone, respectively. Recoveries ranged from 65 to 97% for the two compounds and intra- and inter-day coefficients of variation were always less than 9%. The limit of quantitation of the method was found to be 5 ng/ml for the two compounds, hence allowing its use for single low dose pharmacokinetics.

Cytotoxic effect of 7alpha-hydroxy-4-cholesten-3-one on HepG2 cells: hypothetical role of acetaldehyde-modified delta4-3-ketosteroid-5beta-reductase (the 37-kd-liver protein) in the pathogenesis of alcoholic liver injury in the rat

We recently identified delta4-3-ketosteroid-5beta-reductase as the 37 kd liver protein which is highly susceptible to acetaldehyde modification in rats continuously fed alcohol. The 5beta-reductase is a key enzyme involved in bile acid synthesis. We report here that the ability to degrade 7alpha-hydroxy-4-cholesten-3-one (HCO) was lower in the liver cytosol of alcohol-fed rats than in control animals, suggesting an inhibition of the 5beta-reductase enzyme activity by acetaldehyde modification. We also showed that HCO exhibited a time- and concentration-dependent cytotoxicity to HepG2 cells. HCO cytotoxicity was noticeable at a concentration of 2.5 microg/mL. When 10 microg/mL of HCO was added to confluent cell monolayers, 57% and 37% of cells remained viable after 24 and 48 hours of treatment. The decrease in cell viability was accompanied by an increased lactic dehydrogenase activity in the culture medium. DNA extracted from HCO-treated cells showed no evidence of DNA fragmentation when analyzed by agarose gel electrophoresis. Staining with propidium iodide showed no nuclear condensation in cells. Thus, cell death by HCO treatment was caused by necrosis and not by apoptosis. Various agents, including, serum proteins, hormones, bile acids, antioxidants, Ca++-chelators, Fe++-chelator, CYP450 inhibitor, adenylate cyclase inhibitor, protease inhibitors, and nitric oxide synthase inhibitor, did not protect against HCO cytotoxicity. We speculate that HCO concentrations may be elevated around the pericentral area in the liver after chronic alcohol ingestion, causing local cell necrosis. The release of cellular contents and protein-acetaldehyde adducts (PAAs) may activate nonparenchymal cells and provoke autoimmune reaction. Thus, the formation of the 37 kd-PAA may play an important role in the initiation of alcoholic liver injury.

Polyenylphosphatidylcholine prevents carbon tetrachloride-induced lipid peroxidation while it attenuates liver fibrosis

BACKGROUND/AIMS

Polyenylphosphatidylcholine protects against alcoholic cirrhosis in the baboon and carbon tetrachloride-induced cirrhosis in rats. This study addresses the possible mechanism of the protective effect of polyenylphosphatidylcholine.

METHODS

For 8 weeks, rats were injected with either carbon tetrachloride in peanut oil or peanut oil alone (control), and pair-fed nutritionally adequate liquid diets with equivalent amounts of linoleic acid either as polyenylphosphatidylcholine or as safflower oil. Other rats were injected for 9 weeks with heterologous albumin and fed the same liquid diets. Lipid peroxidation was measured by F2-isoprostanes and 4-hydroxynonenal.

RESULTS

Carbon tetrachloride-induced lipid peroxidation was strikingly attenuated with polyenylphosphatidylcholine supplementation. Levels of hepatic F2-isoprostanes and 4-hydroxynonenal paralleled liver fibrotic scores and collagen accumulation. Polyenylphosphatidylcholine also attenuated the fibrosis induced in rats with human albumin, but in this case, levels of hepatic 4-hydroxynonenal did not change, nor were they significantly affected by polyenylphos-phatidylcholine. Neither carbon tetrachloride injection nor polyenylphosphatidylcholine treatment changed the arachidonic acid content (a major precursor of F2-isoprostanes and 4-hydroxynonenal) in liver phospholipids, and hepatic vitamin E was not significantly altered.

CONCLUSIONS

The hepatic protection of polyenylphosphatidylcholine against carbon tetrachloride appears to be due, at least in part, to an antioxidant effect, whereas the protection against heterologous albumin-induced fibrosis suggests that an additional mechanism, such as stimulation of collagenase activity, may also be responsible.

Polymorphism of alcohol-metabolizing genes affects drinking behavior and alcoholic liver disease in Japanese men

Alcohol is known to be mainly metabolized in the liver by alcohol dehydrogenase 2 (ADH2) and aldehyde dehydrogenase 2 (ALDH2), and cytochrome P-450IIEI. The purpose of this study was to clarify the role of polymorphism of these ethanol-metabolizing enzymes in drinking behavior and the progression of alcoholic liver disease among Japanese men. Polymorphism of the ADH2, ALDH2, and P-45IIEI genes were determined by polymerase chain reaction, followed by restriction fragment-length polymorphism analysis in 189 normal Japanese men and 26 male patients with alcoholic liver disease. Drinking behavior was estimated by self-assessment according to DSM-III-R criteria. Facial flushing was reported in 91 subjects heterozygous for ALDH2*1/*2 and in two subjects homozygous for ALDH2*2/*2, but was not found in 96 subjects homozygous for ALDH2*1/*1. In contrast, polymorphism of ADH2 and P-450IIEI did not differ between flushers and nonflushers. Although the flushers only drank a small amount of alcohol (< 20 g of ethanol/day), the nonflushers were divided into a group of moderate drinkers (20 to 80 g/day; n = 54) and a group of heavy drinkers (> 80 g/day; n = 42). A high preponderance of heterozygosity for the ADH2*1/*2 genes (20/42; 60%) and a high frequency of the ADH2*1 allele were found in heavy drinkers, compared with moderate drinkers. However, cytochrome P-45IIEI gene polymorphism was similar among the moderate and heavy drinkers. Not only a high frequency of the ALDH2*1 and ADH2*1 alleles, but also a high frequency of the P-450IIEI c2 allele was found in the patients with alcoholic liver disease. From these results, the drinking behavior of Japanese men is strongly influenced by the ALDH2*1 allele, and the level of alcohol intake is affected by the ADH2*1 allele, but not by cytochrome P-45IIEI. However, progression to alcoholic liver disease among heavy drinkers may be affected by the cytochrome P-450IIEI c2 allele.

Regulation of the hepatic CYP 2E1 gene during chronic alcohol exposure: lack of an ethanol response element in the proximal 5'-flanking sequence

Chronic exposure to ethanol is known to cause a dramatic increase in the level of CYP 2E1 apoprotein. More recently it has been demonstrated that under certain conditions the mRNA encoding cytochrome P450 2E1(CYP 2E1) is inducible; however, the mechanisms by which these increases occur are not well understood. In the current study, DNase I footprinting assays performed on the first kilobase of the CYP 2E1 5'-flanking sequences resulted in the identification of 13 sequence-specific protected regions using rat liver nuclear extracts isolated from either control or ethanol-treated animals. No differences were observed in the DNase I footprint patterns produced by the two different nuclear extracts. In addition, analysis by electrophoretic mobility shift assays (EMSA) revealed that with one exception, there were no differences in the level of binding complexes between the two extracts. However, EMSA analysis with an oligonucleotide to one footprint site (designated Site C) revealed that in nuclear extracts isolated from ethanol-treated animals there was a 2.9-fold increase in this binding complex when compared to control nuclear extracts. This site was previously shown to contain an HNF-1alpha binding site, and here we demonstrate that bacterially expressed HNF-1alpha in footprint assays bind Site C sequences and that HNF-1alpha transactivates the CYP 2E1 promoter in co-transfection experiments with HNF-1alpha expression plasmid and plasmids containing CYP 2E1 promoter sequences coupled to the chloramphenicol acetyl transferase gene. Furthermore, in contrast to the increase observed by EMSA in Site C binding, no increase was detected in the CYP 2E1 transcriptional rate supported by nuclear extracts from ethanol-treated animals over controls using in vitro transcription assays, suggesting that the increase by ethanol in CYP 2E1 transcription is not mediated through the HNF-1alpha site.

Novel lipid-lowering properties of Vaccinium myrtillus L. leaves, a traditional antidiabetic treatment, in several models of rat dyslipidaemia: a comparison with ciprofibrate

Vaccinium myrtillus L. (blueberry) leaf infusions are traditionally used as a folk medicine treatment of diabetes. To further define this therapeutical action, a dried hydroalcoholic extract of the leaf was administered orally to streptozotocin-diabetic rats for 4 days. Plasma glucose levels were consistently found to drop by about 26% at two different stages of diabetes. Unexpectedly, plasma triglyceride (TG) were also decreased by 39% following treatment. Subsequent to the latter observation, possible lipid-lowering properties of the extract were investigated on other models of hyperlipidaemia and ciprofibrate, a well-established hypolipidaemic drug, was used as a reference compound. Both drug reduced TG levels of rats on hyperlipidaemic diet in a dose-dependent fashion. When administered at single doses over the same experimental period, blueberry and ciprofibrate were effective in lowering TG concentrations in ethanol-treated normolipidaemic animals and in genetically hyperlipidaemic Yoshida rats. Unlike ciprofibrate, however, blueberry failed to prevent the rise in plasma TG elicited by fructose and did not affect free fatty acid levels in any of the above experimental conditions. In rats treated with Triton WR-1339, blueberry feeding induced an hypolipidaemic activity one hour after injection but proved to be ineffective at later time points, thus suggesting that its hypolipidaemic action may reflect improved TG-rich lipoprotein catabolism. In addition, ciprofibrate and the extract were tested for antithrombotic activity using a collagen-triggered model of venous thrombosis in diabetic and Yoshida rats. Only ciprofibrate, however, significantly reduced thrombus formation in diabetics, possibly because of its effects on free fatty acid metabolism, whereas no effect was observed in Yoshida rats. In conclusion, the present findings indicate that active consituent(s) of Vaccinium myrtillus L. leaves may prove potentially useful for treatment of dyslipidaemiae associated with impaired TG-rich lipoprotein clearance.

Effect of ethanol on adenosine triphosphate, cytosolic free calcium, and cell injury in rat hepatocytes. Time course and effect of nutritional status

The events implicated in the early phases of acute ethanol-induced hepatocyte injury and their relation with the nutritional status of the liver are not clearly defined. We aimed to determine the effect of ethanol on ATP and cytosolic free Ca2+ in hepatocytes isolated from fed or fasted rats. Cell injury was assessed by LDH release and trypan blue uptake, ATP by [31P]NMR spectroscopy, and cytosolic free Ca2+ with aequorin. In control conditions, cells from fasted animals had a lower ATP level (-52%) and a higher cytosolic free Ca2+ (+101%) than did those isolated from fed animals. Ethanol caused a dose-dependent cell injury in both groups. At all ethanol doses, greater, damage occurred when using hepatocytes isolated from fasted rats. In both groups, a dose-dependent decrease in ATP content and a rise in cytosolic free Ca2+ were seen. The magnitude of these changes were significantly greater in the fasted group. In conclusion, these data showed that fasting affects the energy status and cytosolic free calcium level in hepatocytes; ethanol causes a dose-dependent cell injury that occurs in association with a fall in ATP and a rise in cytosolic free Ca2+ levels. The nutritional status of an animals is an important determinant of the severity of ethanol-induced damage to liver cells.

Fatty acid composition of liver total lipids in alcoholic patients with and without liver damage

Alcohol ingestion may promote lipid peroxidation, and the presence of polyunsaturated fatty acids in liver lipids may be essential for the generation of liver damage through this mechanism. The aim of this study is to examine fatty acid composition of liver lipids in chronic alcoholics with and without histological liver damage. A percutaneous liver biopsy was performed to 28 patients hospitalized for treatment of their alcoholism. Liver total lipids were extracted from a portion of the tissue sample and fatty acid composition was measured by gas chromatography. Another piece of the sample was sent for histological study. Six patients had histological cirrhosis or alcoholic hepatitis in their biopsies, the rest of the patients had minimal changes. Patients with liver damage had higher levels of oleic acid and total monoenoic fatty acids, a higher 18:1/18:0 ratio, lower levels of polyunsaturated fatty acids, a lower 20:4/18:2 ratio, and a lower peroxidability index in liver total lipids, than patients without liver damage. Alcoholic patients with asymptomatic liver damage have less unsaturated fatty acids in liver total lipids than their counterparts with normal livers.

Role of protein synthesis on ethanol regulation of adenylyl cyclase activity in wild-type S49 murine lymphoma cells

Adenylyl cyclase activity was determined in membranes from wild-type S49 murine lymphoma cells that had been exposed to ethanol for 4 hr. Mn-, NaF-, and forskolin-stimulated adenylyl cyclase activities of cells-pretreated with cycloheximide, puromycin, or serum deprivation-were significantly decreased by treatment with 50 mM of ethanol. As demonstrated for Mn-stimulated activity, the decrease was dose-dependent on ethanol and was temporal; a normal activity recovered after 16-24 hr treatment, even in the presence of cycloheximide and ethanol. Studies with a cell-free membrane system of S49 cells revealed a similar activity decrease after treatment of the membranes with ethanol. In contrast, cells treated with 50 mM of ethanol in a regular culture condition showed no decrease in adenylyl cyclase activity over 24 hr. These results indicate that ethanol regulation of adenylyl cyclase activity in S49 cells depends on reduced or impaired protein synthesis.

Potentiation of mitogen-activated protein kinase by ethanol in embryonic liver cells

Ethanol modulates agonist responses in liver cells, which are the major site of ethanol metabolism. Mitogen-activated protein kinases (MAPKs) are involved in the integration of multiple signaling pathways leading to cellular responses. However, the effect of ethanol on liver MAPK is not known. To this end, we studied the activation of MAPK in a normal mouse embryonic liver cell line (BNLCL2) after acute and chronic exposure to ethanol. Acute exposure to ethanol (0-400 mM) for 1 hr had no effect on either basal or serum- and phorbol-12-myristate-13-acetate (PMA)-stimulated MAPK activity. Chronic exposure to ethanol (0-400 mM) for 24 hr potentiated the stimulation of MAPK by serum, PMA, or thrombin. Maximum potentiation was observed with 200 mM ethanol (2- to 3-fold higher than control cells). Chronic exposure had no significant effect on epidermal growth factor-stimulated MAPK activity. In-gel MAPK assay of cytosolic extracts and of immunoprecipitates obtained with MAPK antibody demonstrated that ethanol potentiated the activation of both p42 and p44 MAPKs. When cells were pretreated with pertussis toxin, the potentiation by ethanol was abolished. It is concluded that ethanol potentiates MAPK in fetal liver cells by a pertussis toxin-sensitive G-protein-dependent mechanism.

Acute and chronic hepatic steatosis lead to in vivo lipid peroxidation in mice

BACKGROUND/AIMS

Several liver diseases that are characterized by chronic steatosis lead to steatohepatitis lesions in some susceptible subjects. We tested the hypothesis that acute or chronic steatosis may lead to lipid peroxidation.

METHODS

Diverse steatogenic treatments were administered to mice, and lipid peroxidation was assessed by measuring thiobarbituric acid reactants in the liver and the exhalation of ethane in breath.

RESULTS

Administration of ethanol (5 g/kg), tetracycline, chlortetracycline, demeclocycline (0.25 mmol/kg each), amineptine (1 mmol/kg), amiodarone (1 mmol/kg), pirprofen (2 mmol/kg), or valproate (2 mmol/kg) led to microvesicular steatosis of the liver and lipid peroxidation. After tetracycline administration, hepatic triglycerides reached a maximum at 24 h and then declined; ethane exhalation followed a similar time course. Microvesicular steatosis and lipid peroxidation were also observed after 4 days of treatment with either ethionine (0.02 mmol/kg daily) or dexamethasone (0.25 mmol/kg daily) or after 7 days of tetracycline (0.25 mmol/kg daily) administration. Administration of ethanol in the drinking water for 5.5 months led to macrovacuolar and microvesicular steatosis, lipid peroxidation, and a few necrotic hepatocytes.

CONCLUSIONS

We conclude that acute or chronic fat deposition due to a variety of compounds was associated with lipid peroxidation in mice. We suggest that the presence of oxidizable fat in the liver leads to peroxidation, and that chronic lipid peroxidation might represent the common (but not exclusive) mechanism for the possible development of steatohepatitis lesions in conditions characterized by chronic steatosis.

Effect of the cytochrome P-450IIE1 genotype on ethanol elimination rate in alcoholics and control subjects

We studied an influence of genetic polymorphisms in the cytochrome P-450IIE1 (CYP2E1) gene on ethanol elimination rate in alcoholic patients and healthy subjects. The CYP2E1 genotype was determined by polymerase chain reaction-restriction fragment length polymorphism method for 124 alcoholics and 54 healthy subjects. There was no significant difference in the gene frequency of CYP2E1 between alcoholics and healthy control subjects. Blood ethanol concentrations in the 65 alcoholics on admission ranged from 0.32 to 4.22 mg/ml. In the patients with the c1/c2 genotype, the elimination rate was significantly correlated with blood ethanol concentration. In each of the three genotypes of CYP2E1, the patients were divided into three groups based on ethanol concentrations. The average of the ethanol elimination rate in the patients with c1/c2 having blood ethanol levels of > or = 2.5 mg/ml was significantly higher than the rates in the two other groups of c1/c2. When blood ethanol levels were > or = 2.5 mg/ml, the elimination rate in the patients with c1/c2 was significantly higher than that in those with c1/c1. Regardless of the CYP2E1 genotype, the elimination rate in the alcoholics was higher than that in the control subjects when blood ethanol levels were < 1.0 mg/ml. These results suggest the possibility that the c2 allele of CYP2E1 Influences the rate of ethanol elimination at high ethanol levels. The rate of ethanol elimination was independent of liver disorder judged by serum total bilirubin values.

Effects of ethanol administration on cerebral non-protein sulfhydryl content in rats exposed to styrene vapour

Glutathione (GSH) and other non-protein sulfhydryls (NPS) are known to protect cells from oxidative stress and from potentially toxic electrophiles formed by biotransformation of xenobiotics. This study examined the effect of a simultaneous administration of styrene and ethanol on NPS content and lipid peroxidation in rat liver and brain. Hepatic cytochrome P450 and cytochrome b5 content, aniline hydroxylase and aminopyrine N-demethylase activities as well as the two major urinary metabolites of styrene, mandelic and phenylglyoxylic acids were also measured. Groups of rats given ethanol for 3 weeks in a liquid diet were exposed, starting from the second week, to 326 ppm of styrene (6 h daily, 5 days a week, for 2 weeks). In control pair-fed animals, styrene produced about 30% depletion of brain NPS and 50% depletion of hepatic NPS. Subchronic ethanol treatment did not affect hepatic NPS levels, but caused 23% depletion of brain NPS. Concomitant administration of ethanol and styrene caused a NPS depletion in brain tissue in the order of 60%. These results suggest that in the rat, simultaneous exposure to ethanol and styrene may lead to considerable depletion of brain NPS. This effect is seen when both compounds are given on a subchronic basis, a situation which better resembles possible human exposure.

The natural history of nonalcoholic fatty liver: a follow-up study

Nonalcohol-induced fatty liver is widely believed to be a benign condition with little or no risk of disease progression. There have been occasional reports of progression to cirrhosis but none in the absence of preexisting fibrosis on the index biopsy specimen even when co-existing hepatitis was present (steatohepatitis). From our histological database (1978 to 1985), we identified 161 patients with fatty liver seen at our institution and traced the case notes of 156. One hundred five patients were initially excluded as having an alcohol-induced cause, and the remaining 51 either were seen in the clinic (37) or had died, in which cases copies of their death certificates were obtained (14). A further 7 patients were excluded after clinic attendance gave evidence of alcohol excess and another 4 after review of their initial biopsy showed the presence of fibrosis or steatohepatitis. The apparent cause of the steatosis in the 40 included patients with strictly nonalcohol-induced pure fatty liver was obesity in 12, diabetes in 4 (1 obese patient), and cachexia associated with extrahepatic malignancy in 6. Four of the remaining 19 had serological evidence of an autoimmune disorder, but none of these had any clinical or histological features of autoimmune liver disease. Nine patients had evidence of hyperlipidemia, 3 of whom were also obese. At a median follow-up of 11 years (7 to 16), 12 of 26 living patients had abnormal results of liver blood tests and had repeat liver biopsies performed. None had progressed to steatohepatitis or cirrhosis; 1 obese patient had developed mild fibrosis 9.8 years after her index biopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of lymphocytes for assessing ethanol-mediated alterations in the expression of hepatic cytochrome P4502E1

The ethanol-inducible cytochrome P4502E1 (2E1) is involved in the bioactivation of numerous hepatotoxins and hepatocarcinogens. Because high levels of expression may enhance the degree and severity of hepatotoxicity from exposure to chemicals metabolized by this enzyme, a relatively noninvasive method to phenotypically distinguish those individuals exhibiting elevated concentrations of 2E1 may be useful. With this in mind, we examined whether ethanol exposure could alter 2E1 in rabbit white blood cells and liver in a similar manner. Microsomes prepared from freshly isolated, rather than cultured cells, were used to immunochemically detect 2E1. The enzyme was found in lymphocytes and neutrophils. Lymphocytes, which comprise the majority of the white cell population in rabbits, were monitored for changes in 2E1 protein levels after ethanol exposure and compared with alterations of the hepatic enzyme. Results presented herein demonstrate that the degree of enhancement in 2E1 expression of lymphocytes and liver was dependent on the length and dose of alcohol exposure. Indeed, correlations were observed between blood alcohol concentrations and 2E1 content in lymphocytes (r = 0.65, p < 0.01) and liver (r = 0.60, p < 0.01). The greatest increase in 2E1 (6- to 10-fold) occurred in both liver and lymphocytes at a dose of 15% ethanol for 12 days of treatment. This induction was evident regardless of whether blood was taken from treated and compared with untreated rabbits or if white cells were obtained from the same animal before and after ethanol exposure. The latter findings demonstrate that changes in lymphocyte 2E1 were caused by ethanol exposure and not to variability in enzyme expression among rabbits. Interestingly, at the 10% dose, elevation of 2E1 was noted as early as 3 days, declined at 6 days, and at 12 and 24 days returned to slightly higher levels than those seen at the 3-day exposure period. This pattern of 2E1 elevation was observed in both the liver and lymphocytes. In fact, at all exposure periods and at the two doses of alcohol examined, a correlation (r = 0.70, p < 0.01) was observed between lymphocyte and liver 2E1 content. Collectively, these studies show that induction of 2E1 in lymphocytes and liver occurs in a parallel fashion. Furthermore, results suggest that blood 2E1 may be used in humans as a phenotypic marker for xenobiotic-promoted alterations in the expression of the liver enzyme. These findings should have a significant impact on in vivo monitoring of this P450 enzyme.

Ethanol-related liver injury in the rat: a model of steatosis, inflammation and pericentral fibrosis

BACKGROUND/AIMS

While several animal models exist for the study of ethanol heptotoxicity, they are limited in their applicability. This paper describes a relatively simple rat model of alcohol-related liver injury.

METHODS

Ethanol was supplied in the drinking water in a concentration of 40% v/v for up to 29 weeks. Animals are concurrently supplied a chow diet which provides adequate protein and choline for normal growth. Total fat intake is low (7% of consumed calories).

RESULTS

Histological changes of steatosis, inflammation, hepatocyte necrosis and pericentral sclerosis were evident in ethanol-treated rat livers. Littermate controls with and without pair-feeding had normal livers. Electron microscopy revealed abnormal mitochondria and a marked proliferation of smooth endoplasmic reticulum in livers of animals fed ethanol. Biochemical analysis revealed that levels of hepatic-free choline were similar in treated and pair-fed control rats. There was an expected increase in the activity of the microsomal enzyme cytochrome P450 2E1 in ethanol-fed rats.

CONCLUSIONS

The model provides a convenient method for the production of alcoholic liver injury, and it may be useful for the study of the pathogenesis of ethanol-related liver disease.

No association between the c2 allele at the cytochrome P450IIE1 gene and alcohol induced liver disease, alcohol Korsakoff's syndrome or alcohol dependence syndrome

Cytochrome P450IIE1 metabolises, and is induced by ethanol. The 5' regulatory sequence of the gene is polymorphic; that identified by the c2 allele has been shown by transfection studies to confer an increased rate of transcription. A recent report indicating an association between this allele and alcohol induced cirrhosis suggests that it may contribute to the genetic vulnerability to this disease. We have examined this polymorphism in patients of western European origin with alcohol induced cirrhosis, alcohol Korsakoff's syndrome and alcohol dependence syndrome. We were unable to detect any association between this allele and any of these diseases.

An endogenous dopaminergic neurotoxin: implication for Parkinson's disease

Oxidation of dopamine by monoamine oxidase results in the endogenous metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL). The toxicity of DOPAL for dopaminergic neurons was investigated using rat neostriatal synaptosomes, PC-12 cells and cultures of fetal rat dissociated mesencephalon. The Na(+)-dependent uptake of [3H]DOPAL in synaptosomes was inhibited by mazindol. DOPAL selectively inhibited dopamine uptake but not [14C]GABA uptake, induced membrane damage and liberation of dopamine into the medium. Incubation of PC-12 cells with 6.5 microM of DOPAL for 24 h caused degeneration of the neuritic process, and the number of viable cells were reduced by 25% of control. There were practically no surviving cells after 24 h of incubation with 33 microM of DOPAL. After 8 h of treatment with 33 microM of DOPAL, dopamine and 3,4-dihydroxyphenylacetic acid content in the cells were reduced by 38% and 53% of control. DOPAL-induced cell damage released lactic acid dehydrogenase into the incubation media. This toxic effect of DOPAL was time- and concentration-dependent. In mesencephalic cultures, after exposure to 33 microM of DOPAL, the surviving TH+ cells showed rounded cell body, and fibre network was highly reduced. These results indicate DOPAL is a neurotoxin and may be involved in the degeneration of dopaminergic neurons.

Liver antioxidant defenses in mice fed ethanol and the AIN-76A diet

The effects of chronic alcohol (EtOH) ingestion on antioxidant defenses in mice fed AIN-76A liquid diets were investigated. C57Bl/6 female mice were divided into three groups and fed the AIN-76A liquid EtOH diet containing EtOH to provide 31% of total caloric intake (TCI), the same basic diet containing EtOH to provide 35% of TCI, or an isocaloric AIN-76A liquid control diet. After 3 weeks, the mice were killed and livers were excised for biochemical analysis. Liver reduced glutathione (GSH) levels, and activities of both Mn-superoxide dismutase (SOD) and Cu/Zn-SOD were significantly decreased by both levels of EtOH. Activities of catalase and glutathione transferase (GT) were significantly increased, whereas glutathione peroxidase (GP) activity was not affected by either level of EtOH. Our previous study using the Lieber-DeCarli liquid EtOH diet caused a decline of total SOD and GP activities. The results suggest that chronic EtOH administration decreases liver antioxidant defenses; however, the mice fed the AIN-76A EtOH liquid diet can maintain a higher antioxidant defense capability than those fed Lieber-DeCarli EtOH liquid diet.

Apoptosis and bcl-2 protein expression in experimental alcoholic liver disease in the rat

We used the intragastric feeding rat model to investigate the relationship between severity of alcoholic liver injury, apoptosis, bcl-2 protein expression, and lipid peroxidation. Rats were fed ethanol with different dietary fats (saturated fat, corn oil, and fish oil) for a 1-month period. Apoptosis was evaluated using an immunohistochemical method, and flow cytometry. Bcl-2 protein concentrations in liver were evaluated by Western blot analysis and lipid peroxidation by measurement of conjugated dienes. Pathological changes (fatty liver, necrosis, and inflammation) were present in corn oil-ethanol and fish oil-ethanol groups only. The highest number of apoptotic cells were seen in the group of rats exhibiting liver injury. The fish oil-ethanol-fed group had the highest concentrations of bcl-2 protein; this protein was localized in the bile duct epithelial and inflammatory cells. A significant correlation was seen between bcl-2 protein assessed densitometrically and the number of inflammatory cells/mm2 (r = 0.78, p < 0.02) and conjugated diene levels (r = 0.82, p < 0.01). Increased numbers of apoptotic cells were seen in rats developing ethanol-induced pathological liver injury. Increased bcl-2 protein concentration are associated with the presence of inflammatory cells and lipid peroxidation.

Structural reorganization in the supraoptic nucleus of withdrawn rats following long-term alcohol consumption

We have recently shown in the supraoptic nucleus (SON) of the rat that prolonged ethanol consumption induces cell degeneration and enlargement of the surviving neurons and of their subcellular organelles. We analyzed the SON of withdrawn rats to evaluate whether it displays any evidence of morphological reorganization following abstinence from ethanol, inasmuch as in this condition the ethanol-induced changes in the plasma levels of neurohormones and plasma osmolality are no longer detectable. A group of 18-month-old withdrawn rats was compared with age-matched, pair-fed control and ethanol-treated rats. To differentiate between the effects of withdrawal and the effects of rehydration, a group of 18-month-old rehydrated rats was also included in this study and compared with age-matched, pair-fed control and dehydrated rats. We estimated the volume of SON, and the total number and mean volume of its neurons. The cross-sectional areas of the vasopressinergic and oxytocinergic populations were also evaluated. At the ultrastructural level, we determined the volumes and surface areas of the rough endoplasmic reticulum and Golgi apparatus, and the volumes of neurosecretory granules and nucleoli. In withdrawn animals, the total number of SON neurons was smaller than in controls, although the neuronal volume was greater. The number of SON neurons did not differ between withdrawn and ethanol-treated rats, despite the reduced volume of SON in the former animals. The decrease of SON volume correlated with and was caused by a reduction in the volume of SON neurons and in the size of the organelles involved in neuro-hormone synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)