Ethanol self-administration and alterations in the livers of the cynomolgus monkey, Macaca fascicularis

Background: Most of the studies of alcoholic liver disease use models in which animals undergo involuntary administration of high amounts of ethanol and consume diets that are often high in polyunsaturated fatty acids. The objectives of this study were (1) to evaluate whether cynomolgus monkeys (Macaca fascicularis) drinking ethanol voluntarily and consuming a diet with moderate amounts of lipid would demonstrate any indices of alcoholic liver disease past the fatty liver stage and (2) to determine whether these alterations were accompanied by oxidative stress. Methods: Six adult male and 6 adult female cynomolgus monkeys were allowed to consume ethanol voluntarily for 18 to 19 months. Additional monkeys were maintained on the same consumption protocol, but were not provided with ethanol. During the course of the study, liver biopsy samples were monitored for lipid deposition and inflammation, serum for levels of liver enzymes, and urine for concentrations of the isoprostane (IsoP) metabolite, 2,3‐dinor‐5,6‐dihydro‐15‐F_2t‐IsoP, a biomarker for oxidative stress. Liver mitochondria were monitored for respiratory control and liver for concentrations of neutral lipids, adenine nucleotides, esterified F₂ isoprostanes, oxidized proteins, 4‐hydroxynonenal (HNE)‐protein adducts, and protein levels of cytochrome P‐450 2E1 and 3A4. Results: Ethanol consumption ranged from 0.9 to 4.05 g/kg/d over the period of the study. Serum levels of aspartate amino transferase were elevated in heavy‐consuming animals compared with those in ethanol‐naïve or moderate drinkers. Many of the ethanol consumers developed fatty liver and most showed loci of inflammation. Both hepatic energy charge and phosphorylation potential were decreased and NADH‐linked respiration was slightly, but significantly depressed in coupled mitochondria as a result of heavy ethanol consumption. The urinary concentrations of 2,3‐dinor‐5,6‐dihydro‐15‐F_2t‐IsoP increased as high as 33‐fold over that observed in ethanol‐abstinent animals. Liver cytochrome P‐450 2E1 concentrations increased in ethanol consumers, but there were no ethanol‐elicited increases in hepatic concentrations of the esterified F₂ isoprostanes, oxidized proteins, or HNE‐protein adducts. Conclusion: Our studies show that cynomolgus monkeys undergoing voluntary ethanol consumption for 1.5 years exhibit many of the features observed in the early stages of human alcoholic liver disease. Ethanol‐elicited fatty liver, inflammation, and elevated serum aspartate amino transferase were evident with a diet that contained modest amounts of polyunsaturated lipids. The dramatic increases in urinary IsoP demonstrated that the animals were being subjected to significant oxidative stress that correlated with their level of ethanol consumption.     

两种调脂药物对高脂血症性脂肪肝治疗的实验性研究.

目的探讨不同作用机制的调脂药(非诺贝特和辛伐他汀)对高脂血症性脂肪肝的作用.方法高脂食饵性喂养诱导大鼠高脂血症性脂肪肝模型.分别给予非诺贝特、辛伐他汀治疗,观察肝指数、肝功能,血脂、肝脂、血清及肝组织过氧化脂质(MDA)含量及组织学的变化.结果非诺贝特显著降低血脂,分别为TC(mmol/L)1.80±0.20与2 10±0.33,TG(mmol/L)0.76±0.18与1.09±0.31、血清及肝组织MDA含量(nmol/ml)分别3.97±0.57与6.89±1.22和75.22±20.88与106.69±15.60,但ALT、ALP、肝脂、肝指数却显著升高,肝组织学呈重度脂肪变;辛伐他汀显著降低血脂、肝脂、血清及肝组织MDA含量,对肝功能无影响,肝组织学接近正常.结论非诺贝特虽可显著降低血脂,但却加重肝内脂质沉积,不宜用于高脂血症性脂肪肝的治疗.辛伐他汀显著降低血脂及肝脂,降低脂质过氧化,,对肝功能无影响,可较安全、有效地用于高脂血症脂肪肝的治疗.     

Plasma HDL Cholesterol and Blood Glucose in Non-insulin-dependent Diabetics Related to Liver Lipids and Microsomal Enzyme Activity

ABSTRACT. Luoma PV, Savolainen MJ, Sotaniemi EA, Arranto AJ, Pelkonen RO. (Clinical Research Unit, Department of Medicine, and Departments of Medical Biochemistry, Pathology and Pharmacology, University of Oulu, Oulu, Finland.) Plasma HDL cholesterol and blood glucose in non-insulin-dependent diabetics related to liver lipids and microsomal enzyme activity. The major lipid predictors of coronary events, plasma high density lipoprotein cholesterol (HDL-C) and the HDL-C/total cholesterol (T-C) ratio, and blood glucose (BG) in 12 subjects with non-insulin-dependent diabetes mellitus were related to hepatic lipids, proteins and microsomal enzyme activity assessed by liver cytochrome P-450 (P-450). Non-insulin-dependent diabetics had low HDL-C/T-C ratio, liver phospholipid (PL) and P-450 and high serum and liver triglyceride (TG) concentrations. Plasma HDL-C was decreased, and BG high, especially in subjects with reduced PL and P-450. The HDL-C/T-C ratio was directly proportional to liver PL and P-450 and unrelated to hepatic TG. Increases in liver PL and microsomal enzyme activity may be favorably reflected both in cholesterol distribution and diabetic control.     

Effects of Ethanol and Carbon Tetrachloride upon Vitamin A Status of Rats

The effects of ethanol and carbon tetrachloride (CCl4) upon tissue vitamin A, liver lipids, liver cytochrome P450 and hepatic morphology were investigated. It was anticipated that CCl4 treatment would have more severe effects upon vitamin A status because CCl4 provides greater hepatic injury than does ethanol. After a 2-week standardization feeding period, young male rats were divided into four groups. For 5 weeks one group of rats (n = 17) received ethanol in liquid diets (30% of calories) while another (n = 8) was exposed to CCl4 inhalation twice a week along with phenobarbital in the diet. All groups received the National Regulatory Commission recommended level for vitamin A. Comparison of ethanol and its pair-fed control group (n = 17) revealed: decreased hepatic vitamin A, no change in serum vitamin A, increased percentage of liver lipid, and cytochrome P450 with moderate fat accumulation in hepatocytes. Comparison of the CCl4-phenobarbital group with pair-fed controls (n = 8) showed: increased serum vitamin A, decreased hepatic vitamin A, increased cytochrome P450, marked hepatic fat accumulation, hepatic cell necrosis, and early cirrhosis. Thus, CCl4 (with phenobarbitol), which is a more potent hepatotoxin as evidenced by a more elevated cytochrome P450 and distorted liver morphology, not only reduced liver vitamin A, but also increased serum vitamin A. The extent of substrate and/or organ specificity remains to be elucidated.     

肝脂复煎剂对实验性脂肪肝的治疗效应

[目的]探讨肝脂复煎剂对实验性脂肪肝的治疗作用.[方法]通过高脂饮食饲养制备大鼠脂肪肝模型;肝脏病理切片证实造模成功.造模大鼠40只随机分为5组,肝脂复低、中、高剂量治疗组,饮食治疗组及模型对照组.分别检测各组大鼠的肝指数(肝重/体重)、肝功能、血脂、血糖、肝脂、血清和肝组织中丙二醛(MDA)及肝组织学改变.[结果]肝脂复煎剂组血脂改善、肝脂显著降低(P＜0.05,＜0.01),血清和肝组织中丙二醛(MDA)显著降低(P＜0.05,＜0.01),肝组织学接近正常.饮食治疗组改善不大.[结论]肝脂复煎剂可有效地用于实验性脂肪肝的治疗.     

Long-Term Ethanol Feeding Enhances Susceptibility of the Liver to Orally Administered Lipopolysaccharides in Rats

Background Endotoxin has been implicated in the pathogenesis and progression of alcoholic liver disease. However, it is still unclear how long-term ethanol feeding affects absorption of endotoxin from the intestine and susceptibility of the liver to gut-derived endotoxin. The object of this study was to determine the effect of long-term ethanol feeding on hepatic susceptibility to orally administered endotoxin.
Methods Male Wistar rats that weighed approximately 150 g were pair-fed with an ethanol-containing liquid diet or a control diet for 35 days. In some experiments, 0, 10, or 20 mg/kg of lipopolysaccharides (LPS) was added to the liquid diet for 7 days beginning on day 29. On day 36, the animals were killed for blood biochemistry and histologic examination of the liver. We also determined plasma endotoxin levels after 20 mg/kg of LPS administration using a gastric tube. In another set of experiments, we determined intestinal permeability using FD4 (fluorescein isothiocyanate-labeled dextran with an average molecular weight of 4000 D).
Results With 10 mg/kg of LPS, serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels were significantly increased in the ethanol-fed rats but not in controls. After 20 mg/kg of LPS administration, more substantial increases in serum ALT and ALP levels were observed in ethanol-fed rats as compared with control diet-fed rats. Plasma endotoxin levels in long-term ethanol-fed rats were higher than those in control rats after intragastric administration of high-dose endotoxin (20 mg/kg). Furthermore, intestinal permeability to FD4 was increased by long-term ethanol administration.
Conclusions Long-term ethanol feeding increases intestinal permeability to and absorption of endotoxin, which can sequentially enhance hepatic susceptibility to orally administered endotoxin. This model has potential as a subclinical experimental model for the study of alcoholic liver disease.     

Ecstasy‐induced toxicity in rat liver

Abstract: Background/Aims: The aim of the present study was to examine the effects of single and repeated administration of 3,4‐methylenedioxymethamphetamine (MDMA, “ecstasy”) on rat liver. Methods: Animals were given an acute (20 mg/kg) and repeated (20 mg/kg, b.i.d., for 4 consecutive days) intraperitoneal dose of MDMA, and at various times after administration the hepatic and serum determinations were made. Results: The effect of acute MDMA administration included increased triglyceride and cholesterol levels and an increase in all enzyme activities 6 h post administration. The toxic effect of MDMA was also observed in other hepatic processes. Glycogen content showed a marked decrease, which was accompanied by a decrease in serum glucose levels. No significant changes in lipid peroxidation and hepatic GSH content were observed. In contrast, multiple MDMA administration produced some evidence of oxidative stress, namely, increased MDA content and decreased GSH content, a small decrease in liver glycogen at 3 h recovering 6 h post dose, no effect on blood glucose and increased AST and ALP activities but no effects on ALT activity. Seven days after the last MDMA injection a tendency towards recovery was shown. Conclusion: Our results show that the liver toxicity caused by MDMA administration involves several mechanisms.     

Decreased in Vivo Rate of Ethanol Metabolism in the Suckling Rat

Blood concentrations of ethanol and acetaldehyde were determined in suckling rats after a single oral ethanol gavage. These results were compared with the hepatic activities of alcohol and aldehyde dehydrogenase. After intragastric administration of 3 g/kg body weight of ethanol, ethanol concentrations were much higher in suckling rats than in adult animals, especially at 90, 120, and 180 min after its administration. In addition, acetaldehyde concentrations were undetectable in suckling rats as opposed to adult rats, in whom micromolar concentrations were detected. Thus, 5- to 30-day-old rats seem to have a limited capacity for in vivo ethanol metabolism. The analysis of hepatic alcohol dehydrogenase activity revealed that it was very low at birth and it increased progressively with time attaining adult levels after 20 days of life. The alcohol dehydrogenase activity present in the liver of suckling rats presented similar Km values and sensitivity to pyrazole as adult rat liver. Thus, the pattern of in vivo ethanol elimination during the suckling period is not explained by hepatic alcohol dehydrogenase activity. Whether that diminished ethanol metabolism is due to slower intestinal ethanol absorption, different ethanol distribution in the body, or diminished hepatic capacity for NADH reoxidation remains to be studied. At birth, hepatic aldehyde dehydrogenase activity was low and it increased reaching adult levels during the suckling period. Adult levels for the component of low Km were attained earlier than for the component of high Km. The low affinity hepatic aldehyde dehydrogenase component in the newborn was different from that in the adult as assessed by kinetic studies and by its sensitivity to disulfiram.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of aging on in vivo and in vitro ethanol metabolism and its toxicity in F344 rats

To investigate the effect of aging on ethanol metabolism, 24 male and female F344 rats aged 2 and 12 mo that were fed a laboratory diet received ethanol (1.2 and 2.5 g/kg body wt) intraperitoneally. In male rats, in vivo ethanol elimination significantly decreased according to age both at high (436 +/- 38 vs. 294 +/- 27 mg/kg.h; p less than 0.01) and low (365 +/- 19 vs. 261 +/- 8 mg/kg.h; p less than 0.01) blood ethanol concentrations. Age did not influence the specific activity of hepatic or gastric alcohol dehydrogenase, whereas the activity was significantly decreased with age in the liver (p less than 0.05) and in the stomach (p less than 0.001) when related to body weight. In addition, the activity of the hepatic microsomal ethanol oxidizing system decreased significantly according to age (8.7 +/- 0.5 vs. 6.00 +/- 0.3 nmol/min.mg micr. protein; p less than 0.001). To study the response of ethanol-metabolizing enzymes to chronic ethanol ingestion, 2- and 19-mo-old male F344 rats were pair-fed nutritionally adequate liquid diets containing 36% of total calories either as ethanol or isocaloric carbohydrate for 3 wk. In this experiment specific alcohol dehydrogenase activity was not significantly affected by age, whereas the hepatic microsomal function estimated by the determination of cytochrome P450, microsomal ethanol oxidizing system, and aniline hydroxylation as well as hepatic mitochondrial low Km-acetaldehyde dehydrogenase activity was found to be markedly depressed with age (p less than 0.01). Chronic ethanol consumption increased microsomal enzyme activities in older rats to levels comparable to those observed in young animals prior to ethanol administration. Chronic ethanol feeding also resulted in an increased hepatic fat accumulation, which was significantly enhanced in older rats. In contrast to male rats, in vivo ethanol metabolism was practically identical for 2- and 12-mo-old female rats. These data demonstrate an enhanced toxicity of alcohol in older compared to younger male but not female rats associated with a delay in alcohol elimination both at high and low ethanol blood concentrations and a decrease in ethanol- and acetaldehyde-metabolizing enzyme activities.     

Effect of moderate alcohol consumption on hypertriglyceridemia: a study in the fasting state.

BACKGROUND: Patients with hypertriglyceridemia (HTG) are generally advised to avoid alcohol, even though moderate alcohol consumption is cardioprotective. Alcohol increases plasma triglyceride concentration transiently in normolipidemic subjects, but whether alcohol consumption per se increases triglyceride concentrations in patients with HTG is unclear. OBJECTIVE: To assess whether baseline fasting triglyceride concentration determines plasma triglyceride concentration after acute oral alcohol intake. METHODS: Twelve persons with fasting triglyceride concentrations of 2.3 to 8.5 mmol/L (200-750 mg/dL) and 12 persons as a non-HTG group were enrolled. Obesity, current smoking, and history of hypertension, diabetes, or excessive alcohol use were exclusionary. Fasted subjects consumed 38 mL of ethanol in water (equivalent, 2 alcoholic drinks); blood samples were collected at baseline and at intervals thereafter for 10 hours. No less than 1 week later, the subjects consumed water alone in a control test. RESULTS: Mean triglyceride values were 4.04+/-0.41 mmol/L (358+/-36.9 mg/dL) and 1.00+/-0.11 mmol/L (89+/-10.2 mg/dL) for the HTG and non-HTG groups, respectively. Despite similar changes with alcohol feeding in plasma ethanol, nonesterified fatty acid, and acetate concentrations, the groups differed in triglyceride response. At 6 hours (peak) compared with baseline, triglyceride concentration increased only 3% in the HTG group but 53% in the non-HTG group. The former change was not significantly different from the effect with water alone (-9.2% from baseline; P = .43), whereas the latter was (-8.0%; P = .003). CONCLUSIONS: Acute alcohol intake alone is not an important determinant of plasma triglyceride concentration in individuals with HTG. Other factors, such as the contemporaneous consumption of fat and alcohol, known to increase triglyceride concentrations synergistically in non-HTG individuals, may be more important.     

Ethanol-Induced Hepatic Triglyceride Accumulation in Mice and Genetic Differences in the Ethanol Physical Withdrawal Syndrome

Three strains of mice (DBA, TO and C5T) were exposed to ethanol vapour in separate inhalation chambers for 10 days. The concentration of ethanol in inspired air was carefully controlled so that similar concentrations of ethanol in blood (c. 2 mg ml^-1) were produced in each strain. No significant differences between strains mere observed, in ethanol or acetaldehyde concentrations in blood or in liver after administration of ethanol for 10 days. On withdrawal of ethanol some mice of each strain were assessed for the ethanol withdrawal syndrome (convulsions, tremor, piloerection, and tail erection) using a subjective scoring system. The remainder were killed for measurement of hepatic triglyceride concentration. The DBA strain of mice showed a very severe ethanol withdrawal syndrome. Hepatic triglyceride concentration in this strain showed an increase of 892 per cent compared to controls. The C57 strain in contrast showed little evidence of a physical withdrawal syndrome, and triglyceride concentrations in liver were increased only 235 per cent above control concentrations. TO mice were intermediate both in withdrawal syndrome severity and in accumulation of triglycerides in liver (365 per cent above control). The results suggest an association between genetic differences in ethanol-induced changes in hepatic lipid metabolism and the seventy of the ethanol physical withdrawal syndrome.     

Subliminal Fas stimulation increases the hepatotoxicity of acetaminophen and bromobenzene in mice

The hepatotoxicity of several drugs is increased by mild viral infections. During such infections, death receptor ligands are expressed at low levels, and most parenchymal cells survive. We tested the hypothesis that subliminal death receptor stimulation may aggravate the hepatotoxicity of drugs, which are transformed by cytochrome P-450 cytochrome P-450 into glutathione-depleting reactive metabolites. Twenty-four-hour-fasted mice were pretreated with a subtoxic dose of the agonistic Jo2 anti-Fas antibody (1 microg per mouse) 3 hours before acetaminophen (500 mg/kg) or 1 hour before bromobenzene (400 mg/kg) administration. Administration of Jo2 alone increased hepatic inducible nitric oxide synthase nitric oxide synthase but did not modify serum alanine aminotransferase (ALT), hepatic adenosine triphosphate (ATP), glutathione (GSH), cytochrome P-450, cytosolic cytochrome c, caspase-3 activity or hepatic morphology. However, pretreating mice with Jo2 further decreased both hepatic GSH and ATP by 40% 4 hours after acetaminophen administration, and further increased serum ALT and the area of centrilobular necrosis at 24 hours. In mice pretreated with the Jo2 antibody before bromobenzene administration, hepatic GSH 4 hours after bromobenzene administration was 51% lower than in mice treated with bromobenzene alone, and serum ALT activity at 24 hours was 47-fold higher. In conclusion, administration of a subtoxic dose of an agonistic anti-Fas antibody before acetaminophen or bromobenzene increases metabolite-mediated GSH depletion and hepatotoxicity. Subliminal death receptor stimulation may be one mechanism whereby mild viral infections can increase drug-induced toxicity.     

细胞色素P450 2E1在大鼠急性肝损伤中的表达及其意义

目的研究细胞色素P4502E1在大鼠急性肝损伤中的表达变化及其意义。方法随机将Wista大鼠分成正常对照组和急性肝损伤组，采用四氯化碳制备急性肝损伤模型，并按染毒时间分为3、6、12、24、36和48h6个亚组，每组5只大鼠。采用western blot方法测定染毒后不同时间点肝组织细胞色素P4502E1蛋白的表达变化；测定大鼠血清ALT、AST水平和肝组织MDA浓度、SOD活性的变化以及采用电子自旋共振（ESR）技术测定大鼠肝组织自由基（ROS）浓度变化，HE染色观察肝组织病理形态学改变；结果四氯化碳可明显导致大鼠肝脏损伤，表现为：血清ALT、AST水平显著升高，肝组织MDA浓度和ROS含量显著增加。SOD活性明显下降，和正常对照组相比，差异均十分显著（P〈0．01）；western blot结果显示：细胞色素P4502E1在正常大鼠肝组织中有表达，染毒3h后表达增强，12h达到高峰，明显高于正常对照组（P〈0．05），其表达趋势与ROS浓度变化相一致。结论细胞色素P4502E1蛋白在大鼠急性肝损伤时表达显著增强，提示其在中毒性肝损伤的发病中可能具重要的病理生理意义，并与四氯化碳诱导的氧化应激反应密切相关。     

Plasma High-Density Lipoproteins and Liver Lipids and Proteins in Man

ABSTRACT. The association of high-density lipoproteins (HDL) in plasma with liver lipids and proteins was investigated in 28 subjects with diagnostic liver biopsy. Lipids and proteins were evaluated in relation to hepatic histology and microsomal enzyme induction, assessed by liver cytochrome P-450. Moderate-severe hepatic parenchymal changes were associated with low liver phospholipids, protein and cytochrome P-450, low plasma HDL cholesterol (HDL-C), and high hepatic triglycerides. Liver microsomal induction accompanying anti-convulsant therapy was associated with high liver phospholipids and protein, high plasma HDL-C, apoproteins A-I and A-II, and high HDL-C/total cholesterol (T-C) ratio. HDL-C, A-I and the HDL-C/T-C ratio were directly proportional to liver phospholipids, protein and cytochrome P-450, inversely related to hepatic triglycerides. Increases in hepatic phospholipids and protein, characteristic of microsomal induction, may lead to the elevation of plasma HDL apoprotein and HDL-C levels and HDL-C/T-C ratios, and thus reduce the risk of coronary heart disease.     

硫酸软骨素对大鼠酒精性脂肪肝模型的影响

目的 观察硫酸软骨素对酒精性脂肪肝的治疗作用。方法 用连续灌服酒精的方法建立大鼠酒精性脂肪肝模型。在造模成功后给予硫酸软骨素治疗4周，观察一般情况及测定血清肝功能指标和血脂参数，并对大鼠肝脏行病理学检查。结果 连续灌服酒精8周后大鼠形成酒精性脂肪肝，给药4周后，硫酸软骨素（25mg/kg）组成显著降低血中丙氨酸氨基转移酶（ALT）和天门冬氨酸氨基转移酶（AST）活性与血中和肝脏中丙二醛（MDA），甘油三酯（TG），总胆固醇（TC）含量，改善肝脏炎症活动度与脂肪性变。结论 硫酸软骨素能改善酒精性脂肪肝大鼠体内脂质代谢，对酒精性脂肪肝具有一定的治疗作用。     

Hepatic, Metabolic and Toxic Effects of Ethanol: 1991 Update

Until two decades ago, dietary deficiencies were considered to be the only reason for alcoholics to develop liver disease. As the overall nutrition of the population improved, more emphasis was placed on secondary malnutrition and direct hepatotoxic effects of ethanol were established. Ethanol is hepatotoxic through redox changes produced by the NADH generated in its oxidation via the alcohol dehydrogenase pathway, which in turn affects the metabolism of lipids, carbohydrates, proteins, and purines. Ethanol is also oxidized in liver microsomes by an ethanol-inducible cytochrome P-450 (P-450IIE1) that contributes to ethanol metabolism and tolerance, and activates xenobiotics to toxic radicals thereby explaining increased vulnerability of the heavy drinker to industrial solvents, anesthetic agents, commonly prescribed drugs, over-the-counter analgesics, chemical carcinogens, and even nutritional factors such as vitamin A. In addition, ethanol depresses hepatic levels of vitamin A, even when administered with diets containing large amounts of the vitamin, reflecting, in part, accelerated microsomal degradation through newly discovered microsomal pathways of retinol metabolism, inducible by either ethanol or drug administration. The hepatic depletion of vitamin A is strikingly exacerbated when ethanol and other drugs were given together, mimicking a common clinical occurrence. Microsomal induction also results in increased production of acetaldehyde. Acetaldehyde, in turn, causes injury through the formation of protein adducts, resulting in antibody production, enzyme inactivation, decreased DNA repair, and alterations in microtubules, plasma membranes and mitochondria with a striking impairment of oxygen utilization. Acetaldehyde also causes glutathione depletion and lipid peroxidation, and stimulates hepatic collagen production by the vitamin A storing cells (lipocytes) and myofibroblasts.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hepatocyte-specific hypoxia-inducible factor-1α is a determinant of lipid accumulation and liver injury in alcohol-induced steatosis in mice

Chronic alcohol causes hepatic steatosis and liver hypoxia. Hypoxia-regulated hypoxia-inducible factor 1-α, (HIF-1α) may regulate liporegulatory genes, but the relationship of HIF-1 to steatosis remains unknown. We investigated HIF-1α in alcohol-induced hepatic lipid accumulation. Alcohol administration resulted in steatosis, increased liver triglyceride levels, and increased serum alanine aminotransferase (ALT) levels, suggesting liver injury in wild-type (WT) mice. There was increased hepatic HIF-1α messenger RNA (mRNA), protein, and DNA-binding activity in alcohol-fed mice compared with controls. Mice engineered with hepatocyte-specific HIF-1 activation (HIF1dPA) had increased HIF-1α mRNA, protein, and DNA-binding activity, and alcohol feeding in HIF1dPA mice increased hepatomegaly and hepatic triglyceride compared with WT mice. In contrast, hepatocyte-specific deletion of HIF-1α [HIF-1α(Hep(-/-) )], protected mice from alcohol- and lipopolysaccharide (LPS)-induced liver damage, serum ALT elevation, hepatomegaly, and lipid accumulation. HIF-1α(Hep(-/-) ), WT, and HIF1dPA mice had equally suppressed levels of peroxisome proliferator-activated receptor α mRNA after chronic ethanol, whereas the HIF target, adipocyte differentiation-related protein, was up-regulated in WT mice but not HIF-1α(Hep(-/-) ) ethanol-fed/LPS-challenged mice. The chemokine monocyte chemoattractant protein-1 (MCP-1) was cooperatively induced by alcohol feeding and LPS in WT but not HIF-1α(Hep(-/-) ) mice. Using Huh7 hepatoma cells in vitro, we found that MCP-1 treatment induced lipid accumulation and increased HIF-1α protein expression as well as DNA-binding activity. Small interfering RNA inhibition of HIF-1α prevented MCP-1-induced lipid accumulation, suggesting a mechanistic role for HIF-1α in hepatocyte lipid accumulation. CONCLUSION: Alcohol feeding results in lipid accumulation in hepatocytes involving HIF-1α activation. The alcohol-induced chemokine MCP-1 triggers lipid accumulation in hepatocytes via HIF-1α activation, suggesting a mechanistic link between inflammation and hepatic steatosis in alcoholic liver disease.     

Silymarin protects against acute ethanol-induced hepatotoxicity in mice

BACKGROUND: Accumulated evidence has demonstrated that both oxidative stress and abnormal cytokine production, especially tumor necrosis factor-alpha (TNF), play important etiological roles in the pathogenesis of alcoholic liver disease (ALD). Agents that have both antioxidant and anti-inflammation properties, particularly anti-TNF production, represent promising therapeutic interventions for ALD. We investigated the effects and the possible mechanism(s) of silymarin on liver injury induced by acute ethanol (EtOH) administration. METHODS: Nine-week-old mice were divided into 4 groups, control, silymarin treatment, EtOH treatment, and silymarin/EtOH treatment, with 6 mice in each group. Because control and silymarin values were virtually identical, only control treatment is shown for ease of viewing. Ethanol-treated mice received EtOH [5 g/kg body weight (BW)] by gavage every 12 hours for a total of 3 doses. Control mice received an isocalorical maltose solution. In the silymarin/EtOH group, silymarin was dissolved in the EtOH and gavaged simultaneously with EtOH at a dose of 200 mg/kg BW. At 4 hours after the last dosing, the mice were anesthetized and subsequent serum alanine aminotransferase (ALT) level, hepatic lipid peroxidation, enzymatic activity of hepatic cytochrome P450 2E1, hepatic TNF-alpha, and glutathione (GSH) levels were measured. Histopathological change was assessed by hematoxylin and eosin staining. RESULTS: Acute EtOH administration caused prominent hepatic microvesicular steatosis with mild necrosis and an elevation of serum ALT activity, induced a significant decrease in hepatic GSH in conjunction with enhanced lipid peroxidation, and increased hepatic TNF production. Supplementation with a standardized silymarin attenuated these adverse changes induced by acute EtOH administration. CONCLUSIONS: Silymarin protects against the liver injury caused by acute EtOH administration. In view of its nontoxic nature, it may be developed as an effective therapeutic agent for alcohol-induced liver disease by its antioxidative stress and anti-inflammatory features.     

排钱草对大鼠实验性肝纤维化的影响

目的:观察排钱草水、醇提取物对肝纤维化的影响。方法:在给大鼠皮下注射CCl_4进行肝纤维化模型制作的同时给予排钱草水、醇提取物(相当于每日原生药5g/ke、3g/kg),给药6周后检测大鼠肝组织羟脯氨酸(Hyp)及血清中谷丙转氨酶(ALT)和碱性磷酸酶(ALP)活性,血清蛋白电泳测定γ-球蛋白,并观察肝脏的组织病理改变,与联苯双酯进行药效对照。结果:排钱草水、醇提取物的高、低剂量组和联苯双酯组均能显著降低肝脏Hyp含量及血清ALT、ALP的活性,降低γ-球蛋白以维持白/球(A/G)比值,对大鼠肝细胞坏死和胶原纤维增生亦有显著减轻作用。结论:排钱草水、醇提取物能减轻CCl_4致大鼠的肝脏损害,有利于减轻肝纤维化。     

Diet induced regulation of genes involved in cholesterol metabolism in rat liver parenchymal and Kupffer cells

BACKGROUND/AIMS: Feeding rodents atherogenic diets enriched in cholesterol or cholic acid changes hepatic cholesterol metabolism. In the present study, the effect of an atherogenic diet enriched in cholesterol and cholic acid on cellular hepatic cholesterol metabolism was studied. METHODS: Gene and protein expression analysis was performed on parenchymal, endothelial, and Kupffer cells isolated from rats fed a chow or atherogenic diet using quantitative real-time PCR and immunoblotting, respectively. RESULTS: The atherogenic diet raised the serum cholesterol concentration 11-fold, mostly in the VLDL fraction, and led to heavy lipid loading of rat liver parenchymal and Kupffer cells. Only moderate changes in the expression of genes involved in cholesterol metabolism were observed in parenchymal cells on the diet, while PPAR delta expression was 6.8-fold decreased. Kupffer cells, however, showed a highly adaptive response with a 2- to 9-fold induction of SR-BI, ABCA1, and ABCG5/G8, and an 82-fold induction in CYP7A1 mRNA expression, respectively. CONCLUSIONS: Heavy lipid loading of parenchymal cells leads to moderate gene expression changes, while Kupffer cells respond in a highly adaptive fashion by stimulating the expression of genes involved in cholesterol metabolism and transport.