Alcohol and the liver: 1994 update

[Preparation of Lieber-DeCarli liquid diet induced alcoholic hepatic injury model in rats]

OBJECTIVE

Duplicating the classical alcoholic hepatic injury model, to provide an ideal animal model for research on prevention and treatment of hepatic injury.

METHODS

According to the prescription of Lieber-DeCarli, the same calorie fluid animal feed, which contained ethanol or non-ethanol, was prepared. Twenty-three rats were divided into normal control group (n=5), control liquid diet group (n=9), ethanol liquid diet group (n=9). Rats in the normal control group were fed normal diet, and rats in the control liquid diet group and ethanol liquid diet group were fed the corresponding diet for eight weeks. The pathologic changes of hepatic tissue were observed. The activities of the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the liver tissue gamma-glutamyltransferase (gamma-GT), the content of triglyceride (TG), and the lipid peroxidation by-products were assayed.

RESULTS

Compared to the normal control and the control liquid diet groups, the activities of ALT, AST, and gamma-GT, and the lipid peroxidation by-products increased significantly in the ethanol liquid diet group. The pathological changes of cellular swelling and fatty degeneration in the ethanol liquid diet group were severe.

CONCLUSION

Alcoholic hepatic injury model can be successfully duplicated by Lieber-DeCarli prescription.

Mechanisms for the anti-inflammatory effects of adiponectin in macrophages

Adiponectin is an adipokine with potent anti-inflammatory properties. The development of alcoholic liver disease is thought to involve increased pro-inflammatory activity, mediated in part by the activation of hepatic macrophages (Kupffer cells). Chronic ethanol feeding sensitizes hepatic macrophages to activation by lipopolysaccharide (LPS), leading to increased production of reactive oxygen species and tumor necrosis factor-alpha (TNF-alpha). Adiponectin can normalize Toll-like receptor-4 (TLR-4) mediated signaling in hepatic macrophages after ethanol feeding, likely contributing to the hepatoprotective effect of adiponectin in the progression of alcoholic liver disease. However, the mechanisms by which adiponectin suppress TLR-4 mediated responses are not well understood. Using the macrophage-like cell line, RAW264.7, we have investigated the molecular mechanisms by which adiponectin suppresses LPS-stimulated TNF-alpha production. Globular adiponectin (gAcrp)-mediated desensitization of LPS-stimulated responses in RAW264.7 macrophages was dependent on the production of the anti-inflammatory cytokine interleukin (IL)-10. gAcrp initially increased TNF-alpha expression in RAW264.7 macrophages; this TNF-alpha then contributed to increased expression of IL-10. This initial gAcrp-mediated increase in TNF-alpha production by macrophages was mediated via activation of ERK1/2-->Egr-1 and nuclear factor (NF)-kappaB-dependent mechanisms. gAcrp-stimulated IL-10 expression was also dependent on the phosphorylation of cAMP response element-binding protein and the cAMP response element in the IL-10 promoter. In summary, these studies reveal a complex, integrated response of macrophages to gAcrp. gAcrp initially activated signaling pathways considered to be pro-inflammatory, with a subsequent increase in the expression of the potent, anti-inflammatory cytokine, IL-10. Increased IL-10 expression was ultimately required for the suppression of TLR4-mediated signaling by gAcrp.

Alcoholic liver disease in the elderly

Although per capita alcohol consumption, and thus the prevalence of alcoholic liver disease, decreases generally with age in Europe and in the United States, recently an increase in alcohol consumption has been reported in individuals over 65 years. Reasons explaining this observation may include an increase in life expectancy or a loss of life partners and, thus, loneliness and depression. Although ethanol metabolism and ethanol distribution change with age, and an elderly person's liver is more susceptible to the toxic effect of ethanol, the spectrum of alcoholic liver diseases and their symptoms and signs is similar to that seen in patients of all ages. However, prognosis of alcoholic liver disease in the elderly is poor. In addition, chronic alcohol consumption may enhance drug associated liver disease and may also act as a cofactor in other liver diseases, such as viral hepatitis and nonalcoholic fatty liver disease.

Age, alcohol metabolism and liver disease

PURPOSE OF REVIEW

Alcohol consumption among the elderly has increased. Alcohol metabolism changes with age and the elderly are more sensitive to the toxic effects; this increased consumption is therefore of great clinical relevance.

RECENT FINDINGS

Metabolism of ethanol changes with advancing age because activity of the enzymes involved, such as alcohol and acetaldehyde dehydrogenase and cytochrome P-4502E1, diminish with age. The water distribution volume also decreases with age. Both lead to increased blood concentrations of ethanol. Also, elderly people take more drugs, and ethanol and these drugs may interact; therefore, alcohol consumption can modify serum drug concentrations and their toxicity. Finally, elderly people may suffer more frequently from other types of liver disease, and alcohol may exacerbate these.

SUMMARY

Over recent decades alcohol consumption has increased among those who are older than 65 years. Alcohol is more toxic in the ageing organism because of changes in its metabolism, distribution and elimination, which lead to central nervous system effects at lower levels of intake; also, ageing organs such as brain and liver are more sensitive to the toxicity of alcohol. For these reasons, alcohol should be used in moderation, especially among those of older age.

Zinc inhibits ethanol-induced HepG2 cell apoptosis

Alcohol consumption produces a variety of metabolic alterations in liver cells, associated with ethanol oxidation and with nonoxidative metabolism of ethanol, among others apoptosis of hepatocytes. As zinc is known as a potent antioxidant and an inhibitor of cell apoptosis, the aim of this paper was to investigate whether zinc supplementation could inhibit ethanol-induced HepG2 apoptosis, and whether this inhibition was connected with attenuation of oxidative stress and modulation of FasR/FasL system expression. The results indicated that zinc supplementation significantly inhibited ethanol-induced HepG2 cell apoptosis (measured by cytochrome c release from mitochondria and caspase-3 activation) by attenuation of reactive oxygen species (ROS) production, increase in the cellular level of GSH, inhibition of ethanol-induced sFasR and FasL overexpression and caspase-8 activation. These results indicate that zinc can inhibit ethanol-induced hepatocyte apoptosis by several independent mechanisms, among others by an indirect antioxidative effect and probably by inhibition of caspase-8 and caspase-9 activation.

Ethanol consumption impairs regulation of fatty acid metabolism by decreasing the activity of AMP-activated protein kinase in rat liver

The mechanisms by which ethanol consumption causes accumulation of hepatic triacylglycerols are complex. AMP-activated protein kinase (AMPK) plays a central role in the regulation of lipid metabolism. Therefore, in the present study we investigated whether AMPK may have a role in the development of ethanol-induced fatty liver. Hepatocytes isolated from rats fed with an ethanol-containing liquid diet showed higher rates of fatty acid and triacylglycerol syntheses, but a decreased rate of fatty acid oxidation, concomitant to a lower activity of carnitine palmitoyltransferase I. Hepatocytes from both ethanol-fed and pair-fed control rats were incubated with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), an AMPK activator in intact cells. In both hepatocyte preparations AICAR strongly inhibited the activity of acetyl-CoA carboxylase in parallel to fatty acid synthesis, but cells from ethanol-fed rats showed significantly lower sensitivity to inhibition by AICAR. Moreover, AICAR strongly decreased triacylglycerol synthesis and increased fatty acid oxidation in control hepatocytes, but these effects were markedly attenuated in hepatocytes from ethanol-fed rats. In parallel, AMPK in liver of ethanol-fed rats showed a decreased specific activity and a lower sensitivity to changes in the AMP/ATP ratio, compared to the enzyme of control rats. These effects are consistent with the impairment of AMPK-mediated regulation of fatty acid metabolism after ethanol consumption, that will facilitate triacylglycerol accumulation. Taken together, these findings suggest that a decreased AMPK activity may have an important role in the development of alcoholic fatty liver.

Risks of combined alcohol/medication use in older adults

BACKGROUND

Many older adults (ie, those aged >65 years) drink alcohol and use medications that may be harmful when consumed together.

OBJECTIVE

This article reviews the literature on alcohol and medication interactions, with a focus on older adults.

METHODS

Relevant articles were identified through a search of MEDLINE and International Pharmaceutical Abstracts (1966-August 2006) for English-language articles. The following medical subject headings and key words were used: alcohol medication interactions, diseases worsened by alcohol use, and alcohol metabolism, absorption, and distribution. Additional articles were identified by a manual search of the reference lists of the identified articles, review articles, textbooks, and personal reference sources.

RESULTS

Many older adults drink alcohol and take medications that may interact negatively with alcohol. Some of these interactions are due to age-related changes in the absorption, distribution, and metabolism of alcohol an medications. Others are due to disulfiram-like reactions observed with some medications, exacerbation of therapeutic effects and adverse effects of medications when combined with alcohol, and alcohol's interference with the effectiveness of some medications.

CONCLUSIONS

Older adults who drink alcohol and who take medications are at risk for a variety of adverse consequences depending on the amount of alcohol and the type of medications consumed. It is important for clinicians to know how much alcohol their older patients are drinking to be able to effectively assess their risks and to counsel them about the safe use of alcohol and medications. Similarly, it is important for older adults to understand the potential risks of their combined alcohol and medication use to avoid the myriad of problems possible with unsafe use of these substances..

The role of acetaldehyde in upper digestive tract cancer in alcoholics

Chronic excessive alcohol consumption is the strongest risk factor for upper aerodigestive tract (UADT) cancer. Multiple mechanisms are involved in alcohol-associated cancer development of the UADT, including acetaldehyde (AA) effects. AA is toxic, mutagenic, and carcinogenic. Evidence of the role of AA in alcohol-associated carcinogenesis derived from genetic linkage studies in alcoholics. Polymorphism or mutation in genes coding for AA generation or detoxification enzymes are associated with increased cancer risk. It has been clearly shown in Asians that individuals carrying the acetaldehyde dehydrogenase 2*2 (ALDH2*2) allele have a significantly increased cancer risk when they consume alcohol. In Caucasians, alcohol dehydrogenase 1*1 (ADH1C*1) allele encodes for an alcohol dehydrogenase (ADH) isoenzyme, which produces 2.5 times more AA than the corresponding allele ADH1C*2. The authors found that the ADH1C*1 allele frequency and rate of homozygosity was significantly associated with an increased risk for alcohol-related cancer. AA seems to be an important factor in alcohol-associated carcinogenesis of the UADT.

Dosage effects of ginkgolide B on ethanol-induced cell death in human hepatoma G2 cells

Ginkgolide B is a major active component of Ginkgo biloba extracts, which has been shown to confer anticancer effects by inducing apoptosis or inhibiting oxidative stress generation. Ethanol induces a wide range of cellular toxicities, many of which have been linked to free radical generation. To further elucidate the cellular effects of ginkgolide B, we examined the dose-response effect of ginkgolide B on ethanol-induced toxicity in human Hep G2 cells. TUNEL and MTT assays revealed that ethanol (50-400 mM) induced apoptotic cell death in human Hep G2 cells, and that this effect was inhibited by low (5-25 microM) doses of ginkgolide B, but enhanced by high (50-100 microM) doses of ginkgolide B. Additional experiments revealed that ethanol treatment directly increased intracellular oxidative stress; this effect was enhanced by high doses of ginkgolide B but decreased following treatment with low concentrations of ginkgolide B. The dose-response effects of ginkgolide B on reactive oxygen species (ROS) generation were directly correlated with cell apoptotic biochemical changes including c-Jun N-terminal kinase (JNK) activation, caspase-3 activation, and DNA fragmentation. These results indicate that treatment dosage may determine the effect of ginkgolide B on ethanol-induced ROS generation and cell apoptosis, and support the notion that an appropriate dosage of ginkgolide B may aid in decreasing the toxic effects of ethanol.

Iron deposition and fat accumulation in dimethylnitrosamine-induced liver fibrosis in rat

AIM: To investigate if iron deposition and fat accumulation in the liver play a pathogenetic role in dimethylnitrosamine (DMN)-induced liver fibrosis in rat.

METHODS: Thirty rats were treated with DMN at does consecutive days of 10 μL/kg daily, i.p., for 3 consecutive day each week for 4 wk. Rats (n = 30) were sacrificed on the first day (model group A) and 21^st d (model group B) after cessation of DMN injection. The control group (n = 10) received an equivalent amount of saline. Liver tissues were stained with hematoxylin & eosin (HE) and Masson and Prussian blue assay and oberserved under electron microscopy. Serum alanine aminotransferase (ALT) and liver tissue hydroxyproline (Hyp) content were tested.

RESULTS: The liver fibrosis did not automatically reverse, which was similar to previous reports, the perilobular deposition of iron accompanied with collagen showed marked characteristics at both the first and 21^st d after cessation of DMN injection. However, fat accumulation in hepatocytes occurred only at the 21^st d after cessation of DMN injection.

CONCLUSION: Iron deposition and fat accumulation may play important roles in pathological changes in DMN-induced rat liver fibrosis. The detailed mechanisms of these characteristics need further research.

Short-term effects of parenteral nutrition of cholestatic infants with lipid emulsions based on medium-chain and long-chain triacylglycerols

OBJECTIVE

Infants with chronic cholestasis may require parenteral nutrition with lipid emulsions to provide energy and essential fatty acids but the optimal strategy is controversial.

METHODS

We studied the effects of parenteral lipid emulsions with long-chain triacylglycerols (LCTs) or a mixture of LCTs and medium-chain triacylglycerols (MCTs/LCTs) on serum bilirubin and lipid metabolism in cholestatic infants who received these 20% emulsions in alternating order for 3 d each, together with a glucose and amino acid infusion.

RESULTS

Of 11 recruited infants, two dropped out because enteral feeding could be established. In nine infants (2-8 mo of age, mean age 4.2 mo) who completed the study, serum bilirubin decreased from baseline to 6 h after the end of LCT infusion (from 8.5 +/- 2.0 to 7.8 +/- 1.8 mg/dL, mean +/- SEM, P < 0.05) and MCT/LCT infusion (7.9 +/- 6.5 to 7.1 +/- 6.5 mg/dL, P < 0.05). Cholesterol, triacylglycerol, and phospholipid concentrations in plasma and in chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein were not changed by either emulsion. Total polyunsaturated fatty acid contents in high-density lipoprotein phospholipids increased during LCT infusion (from 29.8 +/- 0.9 to 35.9 +/- 1.4% wt/wt, P < 0.05) and MCT/LCT infusion (from 30.4 +/- 1.0 to 33.0 +/- 0.7%, P < 0.05). The long-chain polyunsaturated fatty acid docosahexaenoic acid increased only with the LCT infusion. Because docosahexaenoic acid availability during infancy is important for early visual and cognitive development, the use of soybean oil-based lipid emulsions may be preferable for infants with severe progressive cholestasis.

CONCLUSION

The MCT/LCT and LCT emulsions showed a good metabolic tolerance in infants with chronic cholestasis but had a differential effect on high-density lipoprotein phospholipid contents of arachidonic and docosahexaenoic acids.

Therapeutic challenges in hepatitis C-infected injection drug using patients

Hepatitis C Viral (HCV) infection in the injection drug user (IDU) population is a major medical concern. Concurrent substance abuse, co-morbid mental health conditions, poor socioeconomic status and a complex treatment protocol that is often incompatible with the life styles of IDUs combine to account for poor uptake and completion of HCV treatment. This article discusses HCV antiviral treatment issues relevant to IDUs chronically infected with this virus. The effect of non-injected substances of abuse on treatment outcome is considered. Priority issues requiring research are discussed.

Serum matrix metalloproteinase and tissue inhibitor of metalloproteinase concentrations in infertile women achieved pregnancy following IVF-ET

PROBLEM

Matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) play important roles throughout various stages of pregnancy, including embryo implantation, trophoblastic invasion, placentation in early gestation, and cervical dilatation in later gestation, and feto-maternal membrane lysis. It would be beneficial if assessment of serum concentrations of MMP and TIMP could predict successful implantation following in vitro fertilization-embryo transfer (IVF-ET). This study was performed to compare serum MMP and TIMP concentrations between patients with and without the establishment of pregnancy following ET.

METHOD OF STUDY

Ten patients who conceived and 10 patients who did not after IVF-ET were entered in the present study. Only intra-uterine single pregnancies with uneventful courses to term were included in the study subjects. Blood samples were obtained at 7, 14 and 21 days after oocyte retrieval. Serum concentrations of MMP-1, MMP-2, MMP-3, and TIMP-1 were measured using enzyme-linked immunosorbent assay. These variables were compared with estradiol (E(2)), progesterone (P(4)), and betahCG levels in the patients' sera. Clinical pregnancies were diagnosed only when fetal heartbeat was visualized on ultrasound.

RESULTS

There were no significant differences in serum MMP concentrations between the pregnant group and the non-pregnant group. However, serum TIMP-1 concentrations on Days 14 and 21 in the pregnant group were significantly higher than those in non-pregnant group [Day 14: 223.1 +/- 11.9 versus 177.5 +/- 20.6 ng/mL (P = 0.004); Day 21: 215.4 +/- 27.8 versus 181.5 +/- 27.4 ng/mL (P = 0.03)]. Serum TIMP-1 concentrations were also correlated with serum E(2) and P(4) levels (P < 0.0001), but not with those of the MMPs. None of MMP nor TIMP-1 were correlated with serum betahCG level.

CONCLUSIONS

It was demonstrated that the patients who successfully conceived after IVF-ET showed significantly higher levels of TIMP-1 at 14 and 21 days after IVF-ET, but not at day 7; further work will be required to determine if serum TIMP-1 can be used to improve prediction of pregnancy outcome in these patients.

Risk factors and mechanisms of hepatocarcinogenesis with special emphasis on alcohol and oxidative stress

Hepatocellular cancer is the fifth most frequent cancer in men and the eighth in women worldwide. Established risk factors are chronic hepatitis B and C infection, chronic heavy alcohol consumption, obesity and type 2 diabetes, tobacco use, use of oral contraceptives, and aflatoxin-contaminated food. Almost 90% of all hepatocellular carcinomas develop in cirrhotic livers. In Western countries, attributable risks are highest for cirrhosis due to chronic alcohol abuse and viral hepatitis B and C infection. Among those with alcoholic cirrhosis, the annual incidence of hepatocellular cancer is 1-2%. An important mechanism implicated in alcohol-related hepatocarcinogenesis is oxidative stress from alcohol metabolism, inflammation, and increased iron storage. Ethanol-induced cytochrome P-450 2E1 produces various reactive oxygen species, leading to the formation of lipid peroxides such as 4-hydroxy-nonenal. Furthermore, alcohol impairs the antioxidant defense system, resulting in mitochondrial damage and apoptosis. Chronic alcohol exposure elicits hepatocyte hyperregeneration due to the activation of survival factors and interference with retinoid metabolism. Direct DNA damage results from acetaldehyde, which can bind to DNA, inhibit DNA repair systems, and lead to the formation of carcinogenic exocyclic DNA etheno adducts. Finally, chronic alcohol abuse interferes with methyl group transfer and may thereby alter gene expression.

Natural medicines for alcoholism treatment: a review

Alcoholism is a serious problem throughout the world. The development of alcoholism remedies have medical, social and economical significance. In view of the pitfalls of psychological dependence and adverse behavioural effects of synthetic drugs, the development of low toxicity and high efficiency medicines derived from natural products exhibits expansive market prospects. Based on these considerations, we summarize briefly folk application of traditional hangover remedies and clinical application of herbal complex and patent medicines for alcoholism treatment. We have reviewed the effects of natural medicines on intake, absorption and metabolism of alcohol, as well as the protective effects on alcohol-induced acute and chronic tissue injury.

Genetic Polymorphism of CYP2E1 and Digestive Tract Alcohol Damage Among Polish Individuals

BACKGROUND

Genetic polymorphism of enzymes involved in alcohol metabolism plays a relevant role in etiopathogenesis of alcohol disease. The aim of the present study was to find in the Polish population the CYP2E1 genotypes that are likely to be responsible for higher susceptibility to alcohol disease of the liver and chronic alcohol pancreatitis.

METHODS

The CYP2E1 genotype and c1 and c2 alleles frequency were examined in 198 patients. Genotyping of the CYP2E1 was performed using polymerase chain reaction-restriction fragment length polymorphism methods on white cell DNA.

RESULTS

In the examined population encompassing 198 subjects, the c2 allele was present only in 1.5% of patients. It was found only in patients abusing alcohol. In the group of patients with alcoholic cirrhosis, it was present in 3.5% of cases, whereas in patients with chronic alcoholic pancreatitis, in 2.3%. The genotype c1/c2 was present in 3% of subjects. The genotype c2/c2 was not found in any patient. Heterozygotes c1/c2 were present only in patients consuming excessive amounts of ethanol; in 7% of patients with alcoholic cirrhosis and in 4.5% of those with chronic alcoholic pancreatitis. The c2 allele occurred only in men. None of the examined women had the genotype c1/c2.

CONCLUSIONS

Our studies suggest that the frequency of the c2 alleles in Polish population is low. Because of their rare frequency, it is difficult to conclude explicitly that the presence of the c2 allele promotes alcoholic damage to alimentary organs among Poles. It seems, however, that they pose the risk of alcoholic cirrhosis; their role in chronic alcoholic pancreatitis is difficult to assess.

S-adenosyl-methionine decreases ethanol-induced apoptosis in primary hepatocyte cultures by a c-Jun N-terminal kinase activity-independent mechanism

AIM: To determine the role of c-Jun N-terminal kinase (JNK) activity in ethanol-induced apoptosis and the modulation of this signaling cascade by S-Adenosyl-methionine (AdoMet).

METHODS: Primary hepatocyte cultures were pretreated with 100 µmol/L SP600125, a selective JNK inhibitor, 1 mL/L DMSO or 4 mmol/L AdoMet and then exposed to 100 mmo/L ethanol. Hepatocyte apoptosis was determined by the TUNEL and DNA ladder assays. JNK activity and its inhibition by SP600125 and AdoMet were determined by Western blot analysis of c-jun phosphorylation and Bid fragmentation. SP600125 and AdoMet effects on the apoptotic signaling pathway were determined by Western blot analysis of cytochrome c release and pro-caspase 3 fragmentation. The AdoMet effect on glutathione levels was measured by Ellman’s method and reactive oxygen species (ROS) generation by cell cytometry.

RESULTS: The exposure of hepatocytes to ethanol induced JNK activation, c-jun phosphorylation, Bid fragmentation, cytochrome c release and pro-caspase 3 cleavage; these effects were diminished by SP600125, and caused a significant decrease in ethanol-induced apoptosis (P< 0.05). AdoMet exerted an antioxidant effect maintaining glutathione levels and decreasing ROS generation, without a significant effect on JNK activity, and prevented cytochrome c release and pro-caspase 3 cleavage.

CONCLUSION: The JNK signaling cascade is a key component of the proapoptotic signaling pathway induced by ethanol. JNK activation may be independent from ROS generation, since AdoMet which exerted antioxidant properties did not have a significant effect on JNK activity. JNK pathway modulator agents and AdoMet may be components of promising therapies for alcoholic liver disease (ALD) treatment.

Glycoprotein isolated from Acanthopanax senticosus protects against hepatotoxicity induced by acute and chronic alcohol treatment

The protective effect of a 30 kDa glycoprotein (GF-AS) isolated from the stem bark of Acanthopanax senticosus against acute and chronic alcohol-induced hepatotoxicity were studied. N-terminal amino acid sequence of GF-AS showed NH(2)-Val-Ala-Tyr-Pro-Trp-Ala-Gly-Phe-Ala-Leu-Ser-Leu-Glx-Pro-Pro-Ala-Gly-Tyr-. GF-AS significantly increases the activities of alcohol-metabolizing enzymes, including alcohol dehydrogenase, microsomal ethanol metabolizing system, and acetaldehyde dehydrogenase in rats acutely treated with alcohol, resulting in decreased plasma alcohol levels. GF-AS also increases the activities of antioxidant enzymes and glutathione level. Markers of liver injury induced by alcohol: elevated serum levels of aspartate aminotransferase, alanine aminotransferase, triglyceride and cholesterol, are reduced by GF-AS in both acutely and chronically treated rats. The activities of lipogenic enzymes including malic enzyme, glucose-6-phosphate dehydrogenase, and 6-phosphoglucuronic acid dehydrogenase in chronic alcohol-treated rats are significantly decreased by GF-AS. Furthemore, GF-AS improves histological change in fatty liver and hepatic lesions induced by alcohol. Collectively, GF-AS may alleviate alcohol-induced hepatotoxicity through increasing ethanol and lipid metabolism, as well as antioxidant defense systems in livers injured by acute- and chronic-alcohol treatment.

CYP2E1 and catalase influence ethanol sensitivity in the central nervous system

OBJECTIVES

Genetic factors are known to influence the sensitivity and tolerance to ethanol in humans and laboratory animals. Ethanol is metabolized to acetaldehyde mainly by the alcohol dehydrogenase pathway (ADHs) and, to a lesser extent, by microsomal oxidization (CYP2E1) and the catalase-H2O2 system.

METHODS

In this study, we examined the role of CYP2E1 and catalase in ethanol metabolism and sensitivity, using transgenic knockout Cyp2e1(-/-) mice, acatalasemic (Cs/Cs) mice, double mutant Cyp2e1(-/-)/Cs/Cs mice and their respective wild-type counterparts 129/sv, C3H/HeJ, 129/sv X C3H/HeJ mice. Ethanol was administered to the mouse lines and ethanol pharmacokinetics and sleep times were evaluated.

RESULTS

Although the rates of whole blood ethanol elimination following i.p. administration were found to be similar regardless of dose or genetic stock, Cs/Cs, Cyp2e1(-/-) and Cyp2e1(-/-)/Cs/Cs mice exhibited longer ethanol-induced sleep times, especially at higher ethanol doses. This infers that there is less acetaldehyde produced in the brains of these animals and is in opposition to the idea that increased acetaldehyde increases the actions of ethanol. The Cyp2e1(-/-) animals produced lower whole blood levels of acetaldehyde than wild-type controls; however, this difference was seen only at higher doses of ethanol. The amount of acetaldehyde produced following the incubation of ethanol with liver and brain microsomes was greater in tissues derived from 129/sv than in those from Cyp2e1(-/-) mice.

CONCLUSIONS

Although the contribution of CYP2E1 and catalase in ethanol oxidation may be of little significance, these enzymes appear to play a significant role in ethanol sensitivity in the brain.

Hsp70 accumulation and ultrastructural features of lung and liver induced by ethanol treatment with and without l-carnitine protection in rats

This study examined Hsp70 accumulation and the subcellular characteristics of liver and lung when exposed to ethanol (EtOH), with and without L-carnitine protection. Female Sprague-Dawley rats, 150-200 g body weight, were randomized into four groups: Control (CON), Alcohol (ALC), L-carnitine (CAR) and Alcohol-L-carnitine (ALC-CAR). EtOH was administered per os at a dose of 4 g/kg body weight (1 ml) daily for 4 weeks. Before alcohol intake, an oral dose of 500 mg/kg body weight of L-carnitine was also administered to the ALC-CAR group. The liver and lung samples were subjected to Hsp70 Western blot and ultrastructural analysis. The Hsp70 accumulation was higher in the liver than in the lung samples. Hepatic Hsp70 accumulation was similar for all groups in contrast to lung, where the Hsp70 accumulation depends on the group studied. The ultrastructural results showed lung but not liver alterations, evidencing a stressful condition and subsequent cellular injury for lung tissue but not for liver. The ALC-CAR group showed less lung damage than the non-protected group and resembles the general appearance of the CON and CAR groups. EtOH intoxication induced differential cellular response in liver and lung in a dose and tissue dependent manner. L-carnitine seems to reduce lung EtOH-induced subcellular damage. The promotion of heat shock or stress proteins might represent one of the mechanisms involved that need to be further investigated.

Urinary 8-hydoxydeoxyguanosine (8-OHdG) and plasma malondialdehyde (MDA) levels in Aldh2 knock-out mice under acetaldehyde exposure

To clarify the carcinogenicity of acetaldehyde when associated with ALDH (aldehyde dehydrogenase) 2 polymorphism, Aldh2 knock-out (Aldh2-/-) mice and their wild type (Aldh2+/+) mice were exposed to two different concentrations of acetaldehyde (125 ppm and 500 ppm) for two weeks. Aldh2-/- mice, which have the same genetic background as C57BL/6J (wild mice) except for the Aldh2 gene, were used as models of humans who lack ALDH2 activity. Urinary 8-hydroxydeoxyguanosine (8-OHdG) and plasma malondialdehyde (MDA) levels were measured as indicators of oxidative DNA damage and lipid peroxidation, respectively. At 125 ppm acetaldehyde exposure for 12 d, urinary 8-OHdG levels in Aldh2+/+ mice did not increase. However, urinary 8-OHdG levels in Aldh2-/- mice were slightly increased by the end of the exposure. On the other hand, plasma MDA levels did not increase in either Aldh2-/- orAldh2+/+ mice. At 500 ppm, urinary 8-OHdG levels in both Aldh2-/- and Aldh2+/+ mice significantly increased after 6 and 12 d, but there was no genetic difference. On the other hand, plasma MDA levels in Aldh2+/+ and Aldh2-/- mice did not increase at either 125 ppm or 500 ppm after two weeks of exposure. In conclusion, it is suspected that DNA was damaged by acetaldehyde inhalation, and that susceptibility to acetaldehyde varies according to Aldh2 genotype.

Recombinant Hep G2 cells that express alcohol dehydrogenase and cytochrome P450 2E1 as a model of ethanol-elicited cytotoxicity

HepG2 cells were transfected with recombinant plasmids, one carrying the murine alcohol dehydrogenase (ADH) gene and the other containing the gene encoding human cytochrome P450 2E1 (CYP2E1). One of recombinant clones called VL-17A exhibited ADH and CYP2E1 specific activities comparable to those in isolated rat hepatocytes. VL-17A cells oxidized ethanol and generated acetaldehyde, the levels of which depended upon the initial ethanol concentration. Compared with unexposed VL-17A cells, ethanol exposure increased the cellular redox (lactate:pyruvate ratio) and caused cell toxicity, indicated by increased leakage of lactate dehydrogenase into the medium,. Exposure of VL-17A cells to 100mM ethanol significantly elevated caspase 3 activity, an indicator of apoptosis, but this ethanol concentration did not affect caspase 3 activity in parental HepG2 cells. Because ethanol consumption causes a decline in hepatic protein catabolism, we examined the influence of ethanol exposure on proteasome activity in HepG2, VL-17A, E-47 (CYP2E1(+)) and VA-13 (ADH(+)) cells. Exposure to 100mM ethanol caused a 25% decline in the chymotrypsin-like activity of the proteasome in VL-17A cells, but the enzyme was unaffected in the other cell types. This inhibitory effect on the proteasome was blocked when ethanol metabolism was blocked by 4-methyl pyrazole. We conclude that recombinant VL-17A cells, which express both ADH and CYP2E1 exhibit hepatocyte-like characteristics in response to ethanol. Furthermore, the metabolism of ethanol by these cells via ADH and CYP2E1 is sufficient to bring about an inhibition of proteasome activity that may lead to apoptotic cell death.

Saturation of retinol-binding protein correlates closely to the severity of alcohol-induced liver disease

Impaired metabolism of retinol has been shown to occur in alcohol-induced liver disease (ALD). The purpose of the present study was to investigate the saturation of retinol-binding protein (RBP) in 6 patients with different stages of ALD. Hospitalized alcohol consumers (n=118) with different stages of ALD (ALD1: mild stage of liver damage; ALD2: moderately severe changes of the liver with signs of hepatic inflammation; ALD3: severely impaired liver function) and 45 healthy control subjects were nutritionally assessed, and retinol and RBP content was measured in plasma by high-performance liquid chromatography and enzyme-linked immunosorbent assay methods, respectively. No differences were noted in daily retinol intake, but subjects with ALD had significantly lower concentrations of retinol in plasma (ALD1: 1.81+/-0.17 micromol/l [mean+/-S.E.M.]; ALD2: 1.95+/-0.24 micromol/l; ALD3: 0.67+/-0.13 micromol/l) compared to controls (2.76+/-0.19 micromol/l). Subjects of group ALD2 had significantly higher plasma RBP levels than controls (P<.05) and patients with ALD1 (P<.05) and ALD3 (P<.001). The relative saturation of RBP with retinol decreased with severity of ALD (controls: 76.8+/-5.0%; ALD1: 55.8+/-6.5%; ALD2: 43.5+/-6.2%; ALD3: 29.0+/-5.1%). The present study indicates that plasma concentrations of retinol and RBP per se do not correlate to severity of ALD, but rather that the retinol/RBP ratio links to the severity of alcohol-induced liver damage. From these results, a reduced availability of retinol in the periphery due to an altered saturation of RBP can be concluded.

Acetaldehyde-induced interleukin-1beta and tumor necrosis factor-alpha production is inhibited by berberine through nuclear factor-kappaB signaling pathway in HepG2 cells

Alcoholic liver disease (ALD) is one of the most common liver diseases in the world. Increased levels of proinflammatory cytokines, including interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), have been correlated with the patients affected by ALD. However, the direct effect of alcohol in the induction of IL-1beta and TNF-alpha has not been clarified. In this study, we demonstrated that acetaldehyde, the metabolic product of ethanol, was able to induce IL-1beta and TNF-alpha production in HepG2 cells. Nuclear factor-kappaB (NF-kappaB), the transcription factor involved in the regulation of cytokine production, was also activated by acetaldehyde through inhibitory kappaB-alpha (IkappaB-alpha) phosphorylation and degradation. However, the NF-kappaB inhibitors, such as aspirin, cyclosporin A and dexamethasone, inhibited both the acetaldehyde-induced NF-kappaB activity and the induced cytokine production. Therefore, these data suggested that acetaldehyde stimulated IL-1beta and TNF-alpha production via the regulation of NF-kappaB signaling pathway. By screening 297 controlled Chinese medicinal herbs supervised by Committee on Chinese Medicine and Pharmacy at Taiwan, we found that Coptis chinensis (Huang-Lien) and Phellodendron amurense (Huang-Po) were capable of inhibiting acetaldehyde-induced NF-kappaB activity. Berberine, the major ingredient of these herbs, abolished acetaldehyde-induced NF-kappaB activity and cytokine production in a dose-dependent manner. Moreover, its inhibitory ability was through the inhibition of induced IkappaB-alpha phosphorylation and degradation. In conclusion, we first linked the acetaldehyde-induced NF-kappaB activity to the induced proinflammatory cytokine production in HepG2 cells. Our findings also suggested the potential role of berberine in the treatment of ALD.

CD14 promoter polymorphism in Chinese alcoholic patients with cirrhosis of liver and acute pancreatitis

AIM: To investigate the relationship between genetic polymorphism of the CD14 promoter and the occurrence of alcoholic cirrhosis and alcoholic pancreatitis, and to challenge the conclusion made earlier that the patients with acute alcoholic pancreatitis and patients with alcoholic cirrhosis of liver are two different subpopulations.

METHODS: Using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, we determined the polymorphism of CD14 gene and aldehyde dehydrogenase gene 2 (ALDH 2) in 335 alcoholic patients with different organ complications i.e., cirrhosis of liver (n = 100), acute pancreatitis (n = 100), esophageal cancer (n = 82) and avascular necrosis of hip joint (AVN) (n = 53) and 194 non-alcoholic controls in a Chinese group.

RESULTS: The results showed that the carriage of T allele was not different among alcoholic patients with cirrhosis of liver, alcoholic patients with other complication and non-alcoholic controls. On the other hand, the carriage of the C allele was significantly more prevalent for alcoholic pancreatitis than for esophageal cancer (0.79 vs 0.60, P<0.001), alcoholic AVN (0.79vs 0.65, P<0.025) and non-alcoholic controls (0.79 vs 0.68, P<0.025). Furthermore, when only subjects with ALDH2 1-1 genotype were examined, the C allele frequency was significantly more prevalent for alcoholic pancreatitis than for alcoholic liver cirrhosis (0.82 vs 0.69, P<0.025), esophageal cancer (0.82 vs 0.61, P<0.01), alcoholic AVN (0.82 vs 0.64, P<0.01) and non-alcoholic controls (0.82 vs 0.69, P<0.05).

CONCLUSION: The C allele may be associated with some mechanism, which is important in the pathogenesis of alcoholic pancreatitis, and that alcoholic patients with acute pancreatitis and cirrhosis of liver are probably two different subpopulations.

Amelioration effects of traditional Chinese medicine on alcohol-induced fatty liver

AIM: To examine the effects of traditional Chinese medicine (TCM) on alcohol-induced fatty liver in rats. TCM consists of Astragalus membranaceus, Morus alba, Crataegus pinnatifida, Alisma orientale, Salvia miltiorrhiza, and Pueraria lobata.

METHODS: The rats were separated randomly into five groups. One (the CD group) was fed a control diet for 10 wk, another (the ED group) fed an ethanol-containing isocaloric liquid diet for 10 wk, and the last three (the TCM group) were fed an ethanol-containing isocaloric liquid diet for 10 wk and dosed orally with TCM (222 mg/kg•d, TCM222; 667 mg/kg•d, TCM667; and 2 000 mg/kg•d, TCM2000, respectively) weekly during the last 4 wk.

RESULTS: ED group developed fatty liver according to lipid profile and liver histological findings. Compared with the control group, liver/body weight, serum triglyceride (TG) and total cholesterol (TC), liver TG and TC, serum alanine aminotransferase (ALT) and aspartic aminotran-sferase (AST) significantly increased in the ED group. Whereas, in the rats administered with TCM, liver/body weight, serum TG and TC, liver TG and TC, serum ALT and AST were significantly decreased, and the degree of hepatic lipid droplets was markedly improved compared with those in the ED group.

CONCLUSION: TCM treatment causes significant reduction in alcohol-induced lipid hepatic accumulation, reversing fatty liver and liver damage, and can be used as a remedy for alcoholic fatty liver.

Honey-Induced Stimulation of Blood Ethanol Elimination and Its Influence on Serum Triacylglycerol and Blood Pressure in Man

The effect of honey on blood alcohol metabolism and the accompanying changes in serum triacylglycerol and blood pressure were investigated using volunteers. Fifty consenting undergraduates in apparent good health, between the ages of 15 and 30 years (23.6 +/- 7.4), were recruited for the study. The subjects were moderate alcohol drinkers (<30 g ethanol/day), matched in body weight and frame size. The participants were given ethanol (0.5 g/kg) and ethanol + honey (0.5 g/kg + 1.25 ml/kg) on two different occasions separated by 1 week. The results show that honey significantly (p < 0.01) increased blood alcohol disappearance and elimination rates by 32.4 and 28.6%, respectively, but reduced the intoxication time (that is, the time taken to attain zero blood alcohol level) and its degree (the peak blood alcohol level) by 30.0 and 4.4%. Ethanol + honey further increased serum triacylglycerol and blood pressure by 20.8 and 1.3/1.4% when compared with the proportion induced by ethanol after about 10 h of ingestion. The occasional use of honey as an anti-intoxicating agent may be approved. Meanwhile, further studies on how to ameliorate or prevent the associated increase in serum triacylglycerol and blood pressure is required.

Dosage effects of resveratrol on ethanol-induced cell death in the human K562 cell line

Previous studies have established that ethanol induces cell apoptosis and necrosis. However, the precise molecular mechanisms are currently unclear. Here, we show that higher concentrations of ethanol (250-400 mM) induced a shift from apoptotic to necrotic cell death in human K562 cells, and that resveratrol, a grape-derived phytoalexin with known antioxidant and anti-inflammatory properties, inhibited or enhanced ethanol-induced apoptosis/necrosis depending on the treatment dosage. Using the cell permeable dye 2',7'-dichlorofluorescin diacetate (DCF-DA) as an indicator of reactive oxygen species (ROS) generation, we showed that ethanol treatment directly increased intracellular oxidative stress. This intracellular oxidative stress increased in response to high concentrations (100-200 microM) of resveratrol, but remained unchanged following treatment with low concentrations (10-25 microM) of resveratrol. Further studies showed that resveratrol could attenuate or enhance ethanol-induced intracellular oxidative stress generation-dependent on treatment dosage, and that this effect could be correlated with cell apoptosis or necrosis. Importantly, ethanol-induced changes in intracellular ATP levels were also correlated with resveratrol dosage. Taken together, these results indicate that the treatment dosage may determine the effect of resveratrol on ethanol-induced ROS generation, intracellular ATP levels, and cell apoptosis or necrosis. Thus our findings support the possibility that appropriate dosage of resveratrol aids in decreasing the toxic effect of ethanol.

Hepatoprotective role of ferulic acid: a dose-dependent study

Alcohol use is contributing to an unprecedented decline in life expectancy. Damage to the liver after ethanol administration is a well-known phenomenon. Free radical mechanisms have been proposed to play a part in ethanol-induced liver toxicity. Ingestion of diets rich in polyunsaturated fatty acids (PUFAs) along with alcohol is known to result in enhanced liver damage. The present work is aimed at evaluating the protective role of ferulic acid, a naturally occurring plant component, on alcohol- and PUFA-induced liver toxicity. Three different doses of ferulic acid (10, 20, and 40 mg/kg of body weight) were administered to rats given alcohol, heated PUFA (DeltaPUFA), and alcohol + DeltaPUFA. Influence of ferulic acid on alcohol-and PUFA-induced liver damage was evaluated by analyzing the activities of the liver marker enzymes alkaline phosphatase, gamma-glutamyl transferase, alanine transaminase, and aspartate transaminase. The activities of these liver marker enzymes were increased in the alcohol, DeltaPUFA, and alcohol + DeltaPUFA groups but were decreased significantly on treatment with ferulic acid. The low dose (10 mg/kg of body weight) was not effective, but both 20 mg and 40 mg/kg of body weight were found to be effective. The 20 mg/kg of body weight dose was found to be more effective than 40 mg/kg of body weight (the high dose). The administration of ferulic acid to normal rats did not produce any harmful effects. Thus our results show that ferulic acid is an effective anti-hepatotoxic agent without side effects and may be a good candidate in the current search for a natural hepatoprotective agent.

Vitamin B6 intake, alcohol consumption, and colorectal cancer: a longitudinal population-based cohort of women

BACKGROUND & AIMS

Vitamin B6 has a crucial role in 1-carbon metabolism, which involves DNA synthesis and DNA methylation. Aberrations in these processes have been implicated in colorectal carcinogenesis. We examined the association between long-term dietary vitamin B6 intake and risk of colorectal cancer and whether this association is modified by consumption of alcohol, which may disrupt 1-carbon metabolism.

METHODS

Our study population comprised 61,433 women in the population-based Swedish Mammography Cohort. The women were aged 40 to 76 years, had no history of cancer, and completed a food-frequency questionnaire at baseline in 1987-1990. Dietary information was updated in 1997. During a mean follow-up of 14.8 years, 805 incident colorectal cancer cases were diagnosed.

RESULTS

After controlling for age and other potential confounders, long-term intake of dietary vitamin B6 was significantly inversely associated with risk of colorectal cancer (P value for trend = .002). Compared with women in the lowest quintile of vitamin B6 intake, those in the highest quintile had a 34% lower risk (multivariate rate ratio, 0.66; 95% confidence interval, 0.50-0.86). The association was most pronounced among women with moderate to high alcohol consumption. The multivariate rate ratio of colorectal cancer comparing extreme quintiles of vitamin B6 intake was 0.28 (95% confidence interval, 0.13-0.59) among women who consumed > or = 30 g/wk of alcohol (approximately equivalent to 2 drinks per week).

CONCLUSIONS

Findings of this study suggest that vitamin B6 may play a role in the prevention of colorectal cancer, particularly among women who drink alcohol.

Comparative Effects of Curcumin and Its Analog on Alcohol- and Polyunsaturated Fatty Acid-Induced Alterations in Circulatory Lipid Profiles

Excessive alcohol intake induces hyperlipidemia. Studies suggest that natural principles and their analogs are known to possess anti-hyperlipidemic properties. In the present work we tested the effect of curcumin, an active principle of turmeric (Curcuma longa), and a curcumin analog on alcohol- and thermally oxidized polyunsaturated fatty acid (deltaPUFA)- induced hyperlipidemia. Male albino Wistar rats were used for the experimental study. Anti-hyperlipidemic activity of curcumin and curcumin analog was evaluated by analyzing the levels of cholesterol, triglycerides (TGs), phospholipids (PLs), and free fatty acids (FFAs). The results showed that the levels of cholesterol, TGs, PLs, and FFAs were increased significantly in alcohol-, deltaPUFA-, and alcohol + deltaPUFA-treated groups, which were brought down significantly on treatment with either of the curcuminoids. Curcumin analog treatment was found to be more effective than curcumin treatment. From the results obtained, we conclude that both curcumin and its analog effectively protect the system against alcohol- and deltaPUFA-induced hyperlipidemia and are possible candidates for the treatment of hyperlipidemia.

Desensitization of cyclic GMP-mediated regulation of fatty acid metabolism in hepatocytes from ethanol-fed rats

The mechanisms by which ethanol causes accumulation of hepatic triacylglycerols are complex. It has been proposed that nitric oxide/cyclic GMP signaling pathway may be involved in regulation of fatty acid metabolism in the liver. Here, we investigated if this mechanism may have a role in adaptation to ethanol consumption. Hepatocytes were isolated from rats fed with an ethanol-containing liquid diet and pair-fed control rats, and incubated with a range of concentrations of 8-bromo-cyclic GMP. In both types of cells, this cyclic GMP analog inhibited in parallel fatty acid synthesis de novo and acetyl-CoA carboxylase activity. Addition of 8-bromo-cyclic GMP also decreased the rate of palmitate esterification to triacylglycerols and phospholipids, whereas palmitate oxidation was increased. However, in all these metabolic effects, hepatocytes from ethanol-fed rats were significantly less sensitive to the addition of 8-bromo-cyclic GMP. In order to know if this may be a more general mechanism of adaptation to ethanol, we also studied the effects on glucose metabolism. Similarly, hepatocytes from ethanol-fed rats showed a decreased sensitivity in the inhibition by 8-bromo-cyclic GMP of glycogen synthesis, fatty acid synthesis and the synthesis of glycerol backbone of hepatic triacylglycerols. These data suggest that ethanol consumption induces a desensitization of the regulatory effects mediated by cyclic GMP in fatty acid metabolism, contributing to triacylglycerol accumulation in the liver.

The reduced tolerance of rat fatty liver to ischemia reperfusion is associated with mitochondrial oxidative injury

BACKGROUND

Oxidative stress contributes to the pathogenesis of hepatic ischemia-reperfusion injury. This study aimed to determine whether fatty degeneration affects the oxidative damage during warm ischemia reperfusion and whether mitochondria, the major intracellular site of energy synthesis, represent a preferential target of this injury.

MATERIALS AND METHODS

Fed rats with control or fatty liver induced by choline deficiency underwent 60' lobar ischemia and reperfusion. Oxidative damage was assessed by measuring in whole liver tissue and in isolated mitochondria the thiobarbituric acid-reactive substances (TBARs), protein carbonyls (PC), and total and oxidized glutathione (GSH and GSSG) concentrations. The mitochondrial F0-F1-ATPase content and the oxidative phosphorylation activity were also determined. Rat survival and ALT release were assessed as parameters of liver injury.

RESULTS

In the whole liver tissue, with the exception of TBARs, no differences were observed for GSH, GSSG, and PC between the two groups throughout all of the experiment. In contrast, in isolated mitochondria, fatty infiltration was associated with a mild oxidative imbalance already under basal conditions. The preischemic differences in the mitochondrial TBARs, PC, and GSSG levels were significantly amplified by reperfusion in the presence of steatosis. The enhanced oxidative damage was associated to a reduced F0-F1-ATPase content and oxidative phosphorylation activity in fatty liver mitochondria. Finally, serum ALT levels were significantly greater and survival significantly lower in rats with steatotic liver.

CONCLUSIONS

Fatty infiltration exacerbates mitochondrial oxidative injury during warm ischemia reperfusion. The increased oxidative stress can alter mitochondrial functions, including key processes for ATP synthesis, thus, contributing to the reduced tolerance to reperfusion injury.

Ethanol- and acetaldehyde-mediated developmental toxicity in zebrafish

Ethanol is a well-established developmental toxicant; however, the mechanism(s) of this toxicity remains unclear. Zebrafish are becoming an important model system for the evaluation of chemical and drug toxicity. In this study, zebrafish embryos were utilized to compare the developmental toxicity resulting from either ethanol or acetaldehyde exposure. Embryos were exposed to waterborne ethanol concentrations for various lengths of time but encompassed the earliest stages of embryogenesis. The waterborne ethanol concentration that causes 50% mortality (LC(50)) following a 45-h ethanol exposure was approximately 340 mM (1.98% v/v). A number of reproducible endpoints resulted from ethanol exposure and included pericardial edema, yolk sac edema, axial malformations, otolith defects, delayed development, and axial blistering. When the exposure period was reduced, similar signs of toxicity were produced at nearly identical ethanol concentrations. To estimate the embryonic dose following a given waterborne ethanol concentration, a kinetic alcohol dehydrogenase (ADH) assay was adapted. The average embryonic ethanol dose was calculated to be a fraction of the waterborne concentration. Embryos exposed to waterborne acetaldehyde resulted in similar, but not identical, endpoints as those induced by ethanol. Embryos were however, almost three orders of magnitude more sensitive to acetaldehyde than to ethanol. Ethanol and acetaldehyde both negatively impact embryonic development; however, ethanol is more teratogenic based on teratogenic indices (TIs). These results demonstrate that the zebrafish model will provide an opportunity to further evaluate the mechanism of action of ethanol on vertebrate development.

Alcohol in hepatocellular cancer

Hepatocellular cancer accounts for almost half a million cancer deaths a year, with an escalating incidence in the Western world. Alcohol has long been recognized as a major risk factor for cancer of the liver and of other organs including oropharynx, larynx, esophagus, and possibly the breast and colon. There is compelling epidemiologic data confirming the increased risk of cancer associated with alcohol consumption, which is supported by animal experiments. Cancer of the liver associated with alcohol usually occurs in the setting of cirrhosis. Alcohol may act as a cocarcinogen, and has strong synergistic effects with other carcinogens including hepatitis B and C, aflatoxin, vinyl chloride, obesity, and diabetes mellitus. Acetaldehyde, the main metabolite of alcohol, causes hepatocellular injury, and is an important factor in causing increased oxidant stress, which damages DNA. Alcohol affects nutrition and vitamin metabolism, causing abnormalities of DNA methylation. Abnormalities of DNA methylation, a key pathway of epigenetic gene control, lead to cancer. Other nutritional and metabolic effects, for example on vitamin A metabolism, also play a key role in hepatocarcinogenesis. Alcohol enhances the effects of environmental carcinogens directly and by contributing to nutritional deficiency and impairing immunological tumor surveillance. This review summarizes the epidemiologic evidence for the role of alcohol in hepatocellular cancer, and discusses the mechanisms involved in the promotion of cancer.

Moderate alcohol consumption and the gastrointestinal tract

BACKGROUND

A high alcohol intake is significantly associated with diseases of the gastrointestinal tract, but less is known about the effects of moderate consumption, specifically moderate average volume of alcohol consumption.

METHODS

A systematic computer-assisted literature review was completed in order to review current scientific knowledge surrounding this topic.

RESULTS

Moderate alcohol consumption is associated with a number of gastrointestinal health risks, including liver diseases, oropharyngeal cancer, esophageal cancer and pancreatitis but may play a positive role in gastritis and cholelithiasis.

CONCLUSION

Moderate alcohol consumption may play a positive or negative role in disease etiology, but the overall conclusion is that moderate alcohol intake is not a high risk factor for many of the gastrointestinal diseases associated with high levels of consumption. The etiology of alcohol diseases is also linked to patterns of drinking, so this is an important area for future research in this area.

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

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

Elevated PTEN levels account for the increased sensitivity of ethanol-exposed cells to tumor necrosis factor-induced cytotoxicity

Tumor necrosis factor alpha (TNF) is known to be one of the primary causative cytokines inflicting the characteristic damage to hepatocytes seen in alcoholic liver disease. TNF activates both cell survival and death-inducing signaling pathways. The balance between these two prongs determines the fate of the cell and the onset of disease. Ethanol exposure has been shown to alter mitochondrial function, decreasing their threshold for injury. Importantly, mitochondrial injury is a necessary end point of TNF-induced cell killing. It has been shown that ethanol exposure increases the sensitivity of hepatocytes and HepG2E47 cells to TNF-mediated death. The cumulative and terminal effect of the increased sensitivity to TNF caused by ethanol is an induction of a mitochondrial permeability transition. TNF brings about the mitochondrial permeability transition in ethanol-exposed cells due to amplification in the activity of the p38 stress kinase and a diminution in the activity of the antiapoptotic Akt/PKB kinase. The present report identifies an increase of PTEN expression in ethanol-exposed cells as the main causative factor in altering the balance between prosurvival and prodeath signals initiated by TNF. Suppression of the elevated PTEN levels found in ethanol-exposed HepG2E47 cells through the use of RNA interference reversed the ethanol-induced alterations to TNF signaling, resulting in a preservation of mitochondrial function and cell viability.

Alcohol and hepatocellular carcinoma

More than 18 million adults in the United States abuse alcohol, a prevalence 5 times higher than that of hepatitis C. Chronic alcohol use of greater than 80 g/day for more than 10 years increases the risk for hepatocellular carcinoma (HCC) approximately 5-fold; alcohol use of less than 80 g/day is associated with a nonsignificant increased risk for HCC. The risk for HCC in decompensated alcohol induced cirrhosis approaches 1% per year. The risk does not decrease with abstinence, and HCC can occur in a noncirrhotic liver. Alcohol use in chronic hepatitis C doubles the risk for HCC as compared with the risk in hepatitis C alone. Furthermore, there may be synergism between alcohol and hepatitis C in the development of HCC, and in these patients HCC may occur at an earlier age and the HCC may be histologically more advanced. Studies in the United States and Italy suggest that alcohol is the most common cause of HCC (accounting for 32%-45% of HCC). The mechanisms by which alcohol causes HCC are incompletely understood, but may include chromosomal loss, oxidative stress, a decreased retinoic acid level in the liver, altered DNA methylation, and genetic susceptibility. Alcohol use is increasing in many countries, suggesting that alcohol will continue to be a common cause of HCC throughout the world.

Differential effects of alcohol drinking pattern on liver enzymes in men and women

BACKGROUND

Increasing evidence suggests that drinking pattern may have powerful implications for health; however, very few studies have focused on the association between drinking pattern and risk of alcoholic liver damage. This study was aimed at examining the association of gamma-glutamyltransferase (GGT), aspartate aminotransferase, and alanine aminotransferase with current alcohol consumption and with some aspects of drinking pattern (e.g., drinking frequency during the week and in relation to food consumption).

METHODS

A cross-sectional analysis was conducted of a random sample of 2943 white residents of Erie and Niagara Counties in New York State who were 35 to 80 years of age and free from known hepatic disease.

RESULTS

The most significant associations were found for GGT; in both sexes, average levels were significantly higher in current and former drinkers compared with lifetime abstainers. In analyses based on quartiles of alcohol consumption, only participants in the two top quartiles showed significantly elevated enzymes compared with both lifetime abstainers and participants in other quartiles. For drinking pattern, there was evidence of sex-specific associations. In men, daily drinkers showed the highest levels of GGT, whereas in women, the highest level of GGT was observed in weekend drinkers. Women (but not men) who consumed alcohol without food exhibited higher levels of GGT compared with women who consumed alcoholic beverages in relation to food.

CONCLUSIONS

These findings support the hypothesis that, in addition to amount, drinking pattern may affect liver function and that differences exist between sexes with regard to the effect of drinking pattern on liver function and potential liver damage.