Alcoholic Fatty Liver In Mice Research Articles

Gehua Jiejiu Dizhi decoction ameliorates alcoholic fatty liver in mice by regulating lipid and bile acid metabolism and with exertion of antioxidant stress based on 4DLabel-free quantitative proteomic study.

To analyze the effect and molecular mechanism of Gehua Jiejiu Dizhi decoction (, GJDD) on alcoholic fatty live disease (AFLD) by using proteomic methods. The male C57BL/6J mouse were randomly divided into four groups: control group, model group, GJDD group and resveratrol group. After the AFLD model was successfully prepared by intragastric administration of alcohol once on the basis of the Lieber-DeCarli classical method, the GJDD group and resveratrol group were intragastrically administered with GJDD (4900 mg/kg) and resveratrol (400 mg/kg) respectively, once a day for 9 d. The fat deposition of liver tissue was observed and evaluated by oil red O (ORO) staining. 4DLabel-free quantitative proteome method was used to determine and quantify the protein expression in liver tissue of each experimental group. The differentially expressed proteins were screened according to protein expression differential multiples, and then analyzed by Gene ontology classification and Kyoto Encyclopedia of Genes and Genomes pathway enrichment. Finally, expression validation of the differentially co-expressed proteins from control group, model group and GJDD group were verified by targeted proteomics quantification techniques. In semiquantitative analyses of ORO, all kinds of steatosis (ToS, MaS, and MiS) were evaluated higher in AFLD mice compared to those in GJDD or resveratrol-treated mice. 4DLabel-free proteomics analysis results showed that a total of 4513 proteins were identified, of which 3763 proteins were quantified and 946 differentially expressed proteins were screened. Compared with the control group, 145 proteins were up-regulated and 148 proteins were down-regulated in the liver tissue of model group. In addition, compared with the model group, 92 proteins were up-regulated and 135 proteins were down-regulated in the liver tissue of the GJDD group. 15 differentially co-expressed proteins were found between every two groups (model group vs control group, GJDD group vs model group and GJDD group vs control group), which were involved in many biological processes. Among them, 11 differentially co-expressed key proteins (Aox3, H1-5, Fabp5, Ces3a, Nudt7, Serpinb1a, Fkbp11, Rpl22l1, Keg1, Acss2 and Slco1a1) were further identified by targeted proteomic quantitative technology and their expression patterns were consistent with the results of 4D label-free proteomic analysis. Our study provided proteomics-based evidence that GJDD alleviated AFLD by modulating liver protein expression, likely through the modulation of lipid metabolism, bile acid metabolism and with exertion of antioxidant stress.

Physicochemical properties of superfine grinding-microwave modified artichoke soluble dietary fiber and their alleviation of alcoholic fatty liver in mice.

The effects of superfine grinding (SG) and microwave treatment (MT) on the structure and physicochemical properties of artichoke soluble dietary fiber (ASDF) and its protective effects on mice with alcoholic fatty liver (AFL) were studied. We compared the changes in structural characteristics and physicochemical properties of ASDF, SG-ASDF (ASDF treated by SG), MT-ASDF (ASDF treated by MT), and CM-ASDF (ASDF treated by SG and MT). Moreover, we evaluated the effects of the obtained ASDF on the growth characteristics, blood lipid levels, and liver of mice with AFL. Our results of the study showed that CM-ASDF had a more concentrated and uniform particle size, a higher extraction rate of ASDF and significantly improved water-holding capacity (WHC), oil-holding capacity (OHC) and water swelling capacity (WSC) of ASDF (p < 0.05). After the ASDF intervention, mice with AFL exhibited a significant improvement in body lipid levels and reduce liver inflammation. Specifically, aspartate aminotransferase (AST), alanine aminotransferase (ALT), malonaldehyde (MDA), Tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6) were significantly decreased, while superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were significantly increased (p < 0.05). And the hematoxylin-eosin (HE) staining results showed significant improvement of hepatic steatosis in mice with AFL. In summary, our study found that both SG and MT could improve the structure and physicochemical properties of ASDF, with CM-ASDF being the most effective. Additionally, CM-ASDF was selected to continue the investigation and demonstrated an excellent protective effect on mice with AFL, with the high dose group (H-ASDF) showing the greatest benefit. These findings provided some new insights for future comprehensive utilization of ASDF and drug development for the treatment of AFL.

Alcoholic fatty liver is blunted by rFGF21 administration in mice lacking adipose FGFR1: the role of FGF21 in PPARα‐mediated regulation of adipose tissue mass

Fibroblast growth factor 21 (FGF21) regulates lipid metabolism via fibroblast growth factor receptor 1 (FGFR1). FGF21 protects against alcoholic fatty liver, which is still observed in mice lacking liver FGFR1, suggesting the involvement of extra‐hepatic FGFR1 in mediating alcoholic fatty liver. We have previously shown that, in a chronic Lieber‐DeCarli model, the peroxisome proliferator‐activated receptor‐α (PPARα) agonist WY‐14,643 induced FGF21 and adipose atrophy but failed to protect against alcoholic fatty liver in mice lacking adipose FGFR1. In this study we tested the role of the FGF21 in regulation of adipose tissue mass and ethanol induced‐hepatic fat (triglyceride, TG) accumulation in mice lacking adipose FGFR1. In binge alcohol model, male adipose FGFR1 knockout mice (fgfr1adipoQ‐cre) and corresponding normal control (fgfr1fl/fl) mice were fed liquid control diet with or without 20 mg/L WY‐14,643 for 2 weeks followed by a binge ethanol gavage at 5 g/kg, adipose tissue mass and serum free fatty acid were decreased by WY‐14,643 in the fgfr1adipoQ‐cremice but not in the fgfr1fl/flmice. However, in contrast to the chronic model, the binge ethanol‐induced liver TG accumulation was blunted by WY‐14,643 to a greater extent in the fgfr1adipoQ‐cremice than in the fgfr1fl/flmice. Consistently, on top of WY‐14,643 feeding, circulating FGF21 was elevated by binge ethanol to a greater extent in the fgfr1adipoQ‐cre mice than in the fgfr1fl/fl mice. To test the involvement of the FGF21 in adipose atrophy and the less extent of hepatic fat accumulation in the fgfr1adipoQ‐cremice, recombinant mouse FGF21 (rFGF21) was injected intraperitoneally at 0.4 mg/kg to the 3‐week ethanol fed fgfr1adipoQ‐cre mice and fgfr1fl/fl mice during the last 10 days of the ethanol feeding. Consistent with FGFR1‐dependent effects of WY‐14,643 on adipose atrophy and liver fat accumulation, on the top of chronic ethanol diet, rFGF21 administration induced adipose atrophy, blunted liver TG accumulation and serum TG elevation to a greater extent in the fgfr1adipoQ‐cre mice than in the fgfr1fl/fl mice. These results indicated the consistency of adipose FGFR1 dependent effect of WY‐14,643 and FGF21 in PPARα‐mediated regulation of adipose tissue mass and fat mobilization from adipose tissues to the liver.

PPARα agonist WY-14,643 induces the PLA2/COX-2/ACOX1 pathway to enhance peroxisomal lipid metabolism and ameliorate alcoholic fatty liver in mice

Peroxisome proliferator-activated receptor α (PPARα) regulates fatty acid oxidation (FAO). Usually, very-long chain fatty acids are first activated by acyl-CoA synthetase (ACS) to generate acyl-CoA for oxidation by acyl-CoA oxidase (ACOX) in peroxisomes, and the resultant shorter chain fatty acids will be further oxidized in mitochondria. ACS long-chain family member 4 (ACSL4) preferentially uses arachidonic acid (AA) as substrates to synthesize arachidonoyl-CoA. Arachidonoyl-CoA is usually esterified into phospholipids. When AA is released by phospholipase A2 (PLA2) from phospholipids, it will be used for prostaglandin synthesis by cyclooxygenases (COX). In this study, when PPARα agonist WY-14,643 was mixed in liquid Lieber-DeCarli ethanol or control diets and fed to mice, liver PLA2, COX-2, and ACOX1 were induced but ACSL4 was inhibited, suggesting that AA released by PLA2 from phospholipid will be metabolized to prostaglandin via COX-2 instead of being synthesized into acyl-CoA by ACSL4. However, liver prostaglandin E2 (PGE2), a major component of prostaglandin, was not increased with the induced COX-2 but decreased by WY-14,643. ACOX1 specific inhibitor mixed in the liquid diets restored both the WY-14,643-suppressed liver TG and PGE2, but COX-2 specific inhibitor celecoxib mixed in the liquid diets reversed the WY-14,643-suppressed liver TG but not liver PGE2 contents. These results suggest that induction of PLA2, COX-2 and ACOX1 orchestrates to increase oxidation of AA/PGE2, which constitutes one new mechanism by which PPARα induces peroxisomal FAO and inhibits ethanol-induced liver fat accumulation.

Fermented Curcuma longa L. Prevents Alcoholic Fatty Liver Disease in Mice by Regulating CYP2E1, SREBP-1c, and PPAR-α.

We examined the efficacy of fermented Curcuma longa L. (FT) on the development of alcoholic fatty liver in mice and investigated the underlying mechanism. The protective potential of FT against ethanol-induced fatty liver was determined using C57BL/6 male mice allocated into four groups (8 mice/group). Control groups received either distilled water or 5 g/kg body weight (b.w.) per day ethanol for 8 days. Treatment groups were administered either 300 mg/kg b.w. per day of milk thistle or FT before receiving ethanol. FT contained a higher amount of caffeic acid and tetrahydrocurcumin than C. longa. FT pretreatment significantly suppressed the elevated hepatic lipid droplets associated with ethanol ingestion. In comparison with ethanol-treated control, FT pretreated mice showed inhibited cytochrome P4502E1 (CYP2E1), sterol regulatory element-binding protein-1 (SREBP-1c), and acetyl-CoA carboxylase production but elevated AMP-activated protein kinase, peroxisome proliferator-activated receptor-alpha (PPAR-α), and carnitine palmitoyltransferase 1 (CPT-1) levels. Taken together, FT is a promising hepatoprotectant for preventing of alcoholic fatty liver through modulating fatty acid synthesis and oxidation.

AS112 - Roseburia spp. abundance associates with alcohol consumption in humans and its administration ameliorates alcoholic fatty liver in mice

AS112 - Roseburia spp. abundance associates with alcohol consumption in humans and its administration ameliorates alcoholic fatty liver in mice

Roseburia spp. Abundance Associates with Alcohol Consumption in Humans and Its Administration Ameliorates Alcoholic Fatty Liver in Mice

Although a link between the gut microbiota and alcohol-related liver diseases (ALDs) has previously been suggested, the causative effects of specific taxa and their functions have not been fully investigated to date. Here, we analyze the gut microbiota of 410 fecal samples from 212 Korean twins by using the Alcohol Use Disorders Identification Test (AUDIT) scales to adjust for host genetics. This analysis revealed a strong association between low AUDIT scores and the abundance of the butyrate-producing genus Roseburia. When Roseburia spp. are administered to ALD murine models, both hepatic steatosis and inflammation significantly improve regardless of bacterial viability. Specifically, the flagellin of R.intestinalis, possibly through Toll-like receptor 5 (TLR5) recognition, recovers gut barrier integrity through upregulation of the tight junction protein Occludin and helps to restore the gut microbiota through elevated expression of IL-22 and REG3γ. Our study demonstrates that Roseburia spp. improve the gut ecosystem and prevent leaky gut, leading to ameliorated ALDs.

Suppressed hepatocyte proliferation via a ROS-HNE-P21 pathway is associated with nicotine- and cotinine-enhanced alcoholic fatty liver in mice

CYP2A5 is a major enzyme responsible for nicotine and cotinine metabolism in mice. Nicotine and cotinine enhance alcoholic fatty liver in wild type (WT) mice but not in CYP2A5 knockout (KO) mice, and reactive oxygen species (ROS) generated during the CYP2A5-mediated metabolism contributes to the enhancing effect. In combination with ethanol, nicotine and cotinine increased lipid peroxidation end product 4-hydroxynonenal (HNE) in WT mice but not in KO mice. In ethanol-fed KO mice, only 5 and 10 genes were regulated by nicotine and cotinine, respectively. However, in ethanol-fed WT mice, 59 and 104 genes were regulated by nicotine and cotinine, respectively, and 7 genes were up-regulated by both nicotine and cotinine. Plin 2 and Cdkn1a are among the 7 genes. Plin2 encodes adipose differentiation-related protein (ADRP), a lipid droplet-associated protein, which was confirmed to be increased by nicotine and cotinine in WT mice but not in KO mice. Cdkn1a encodes P21 and elevated P21 in nuclei was also confirmed. HNE can increase P21 and P21 inhibit cell proliferation. Consistently, hepatocyte proliferation markers proliferating cell nuclear antigen (PCNA) and Ki67 were decreased in WT mice but not in KO mice by nicotine/ethanol and cotinine/ethanol, respectively. These results suggest that inhibition of liver proliferation via a ROS-HNE-P21 pathway is involved in nicotine- and cotinine-enhanced alcoholic fatty liver.

Nicotine enhances alcoholic fatty liver in mice: Role of CYP2A5

Tobacco and alcohol are often co-abused. Nicotine can enhance alcoholic fatty liver, and CYP2A6 (CYP2A5 in mice), a major metabolism enzyme for nicotine, can be induced by alcohol. CYP2A5 knockout (cyp2a5−/−) mice and their littermates (cyp2a5+/+) were used to test whether CYP2A5 has an effect on nicotine-enhanced alcoholic fatty liver. The results showed that alcoholic fatty liver was enhanced by nicotine in cyp2a5+/+ mice but not in the cyp2a5−/− mice. Combination of ethanol and nicotine increased serum triglyceride in cyp2a5+/+ mice but not in the cyp2a5−/− mice. Cotinine, a major metabolite of nicotine, also enhanced alcoholic fatty liver, which was also observed in cyp2a5+/+ mice but not in the cyp2a5−/− mice. Nitrotyrosine and malondialdehyde (MDA), markers of oxidative/nitrosative stress, were induced by alcohol and were further increased by nicotine and cotinine in cyp2a5+/+ mice but not in the cyp2a5−/− mice. Reactive oxygen species (ROS) production during microsomal metabolism of nicotine and cotinine was increased in microsomes from cyp2a5+/+ mice but not in microsomes from cyp2a5−/− mice. These results suggest that nicotine enhances alcoholic fatty liver in a CYP2A5-dependent manner, which is related to ROS produced during the process of CYP2A5-dependent nicotine metabolism.

The Detrimental Role Played by Lipocalin-2 in Alcoholic Fatty Liver in Mice

We have previously shown that the ethanol-mediated elevation of lipocaline-2 (LCN2) is closely associated with the development of alcoholic fatty liver disease (AFLD) in mice. Herein, we aimed to understand the functional significance of LCN2 induction by ethanol and to explore its underlying mechanisms. We evaluated the effects of LCN2 in an invitro cellular alcoholic steatosis model and in an animal study using wild-type and LCN2 knockout mice fed for 4 weeks with an ethanol-supplemented Lieber-DeCarli diet. In the cellular model of alcoholic steatosis, recombinant LCN2 or overexpression of LCN2 exacerbated ethanol-induced fat accumulation, whereas knocking down LCN2 prevented steatosis in hepatocytes exposed to ethanol. Consistently, removal of LCN2 partially but significantly alleviated alcoholic fatty liver injury in mice. Mechanistically, LCN2 mediates detrimental effects of ethanol in the liver via disrupted multiple signaling pathways, including aberrant nicotinamide phosphoribosyltransferase-sirtuin 1 axis, perturbed endocrine metabolic regulatory fibroblast growth factor 15/19 signaling, and impaired chaperone-mediated autophagy. Finally, compared with healthy human livers, liver samples from patients with AFLD had lower gene expression of several LCN2-regualted molecules. Our study demonstrated a pivotal and causal role of LCN2 in the development of AFLD and suggested that targeting the LCN2 could be of great value for the treatment of human AFLD.

Docosahexaenoic acid supplementation failed to attenuate chronic alcoholic fatty liver in mice.

Docosahexaenoic acid supplementation failed to attenuate chronic alcoholic fatty liver in mice.

Emodin Ameliorates Ethanol-Induced Fatty Liver Injury in Mice

The liver plays a central role in ethanol (EtOH) metabolism, and oxidative stress is implicated in alcohol-mediated liver injury. The present study aimed to investigate the role of emodin in EtOH-induced fatty liver injury. Liver histology, biochemistry and gene-expression studies were performed. Mice fed with an EtOH-containing diet exhibited severe macrovesicular steatosis and higher serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. However, emodin ameliorated liver steatosis and lowered ALT and AST. Emodin also decreased hepatic triglyceride in mice fed with EtOH. In addition, emodin attenuates Oil Red O staining in alcoholic fatty liver in mice. Hepatic cytochrome P450 2E1 protein levels were upregulated in EtOH-fed mice, but downregulated in emodin-treated mice. In addition, emodin decreased hepatic oxidative stress. Furthermore, emodin significantly reduced liver α-smooth muscle actin and collagen type I, whereas it increased the mRNA levels of PPAR-γ. Taken together, emodin plays protective roles in alcohol-mediated liver steatosis.

CMZ Reversed Chronic Ethanol-Induced Disturbance of PPAR-α Possibly by Suppressing Oxidative Stress and PGC-1α Acetylation, and Activating the MAPK and GSK3β Pathway

BackgroundCytochrome P4502E1 (CYP2E1) has been suggested to play critical roles in the pathogenesis of alcoholic fatty liver (AFL), but the underlying mechanisms remains unclear. The current study was designed to evaluate whether CYP2E1 suppression by chlormethiazole (CMZ) could suppress AFL in mice, and to explore the underlying mechanisms.MethodsMice were treated with or without CMZ (50 mg/kg bw, i.p.) and subjected to liquid diet with or without ethanol (5%, w/v) for 4 weeks. Biochemical parameters were measured using commercial kits. The protein and mRNA levels were detected by western blot and qPCR, respectively. Histopathology and immunohistochemical assay were performed with routine methods.ResultsCYP2E1 inhibition by CMZ completely blocked AFL in mice, shown as the decline of the hepatic and serum triglyceride levels, and the fewer fat droplets in the liver sections. Chronic ethanol exposure led to significant decrease of the mRNA and protein levels of peroxisome proliferator-activated receptor α (PPAR-α), which was blocked by CMZ co-treatment. CMZ co-treatment suppressed ethanol-induced oxidative stress, overproduction of tumor necrosis α (TNF-α), and decrease of protein levels of the PPAR-α co-activators including p300 and deacetylated PGC1-α. Furthermore, CMZ co-treatment led to the activation of AMP-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK), and PI3K/Akt/GSK3β pathway. However, chronic ethanol-induced decline of acyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) protein levels was partially restored by CMZ, while the activation of autophagy appeared to be suppressed by CMZ.ConclusionThese results suggested that CMZ suppressed chronic ethanol-induced oxidative stress, TNF-α overproduction, decline of p300 protein level and deacetylation of PGC1-α, and activated AMPK, MAPK, and PI3K/Akt/GSK3β pathway, which might contribute to the activation of PPAR-α and account for the protection of CMZ against AFL.

Wild bitter gourd protects against alcoholic fatty liver in mice by attenuating oxidative stress and inflammatory responses

Bitter gourd (Momordica charantia L.) is a common vegetable grown widely in Asia that is used as a traditional medicine. The objective of this study was to investigate whether wild bitter gourd possessed protective effects against chronic alcohol-induced liver injury in mice. C57BL/6 mice were fed an alcohol-containing liquid diet for 4 weeks to induce alcoholic fatty liver. Meanwhile, mice were treated with ethanol extracts from four different wild bitter gourd cultivars: Hualien No. 1', Hualien No. 2', Hualien No. 3' and Hualien No. 4'. The results indicated that the daily administration of 500 mg kg body weight(-1) of a Hualien No. 3' extract (H3E) or a Hualien No. 4' extract (H4E) markedly reduced the steatotic alternation of liver histopathology. In addition, the activation of serum aminotransferases (AST and ALT) and the accumulation of hepatic TG content caused by alcohol were ameliorated. The hepatoprotective effects of H3E and H4E involved the enhancement of the antioxidant defence system (GSH, GPx, GRd, CAT and SOD), inhibition of lipid peroxidation (MDA) and reduction of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) in the liver. Moreover, H3E and H4E supplementation suppressed the alcohol-induced elevation of CYP2E1, SREBP-1, FAS and ACC protein expression. These results demonstrated that ethanol extracts of Hualien No. 3' and Hualien No. 4' have beneficial effects against alcoholic fatty liver, in which they attenuate oxidative stress and inflammatory responses.

Metabolomics of ginger essential oil against alcoholic fatty liver in mice.

Fatty liver is significantly associated with hepatic cirrhosis and liver cancer. Excessive alcohol consumption causes alcoholic fatty liver disease (AFLD). Ginger has been reported to exhibit antioxidant potential and hepatoprotective activity. In the present study, a mouse model for AFLD was developed by employing male C57BL/6 mice that were fed an alcohol-containing liquid diet (Lieber-DeCarli diet) ad libitum. In the treatment groups, ginger essential oil (GEO) and citral were orally administered every day for 4 weeks. Serum biochemical analysis, antioxidant enzyme activity analysis, and histopathological evaluation revealed that GEO and citral exhibited hepatoprotective activity against AFLD. Metabolites in serum samples were profiled by high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS). Metabolomic data indicated the amounts of metabolites such as d-glucurono-6,3-lactone, glycerol-3-phosphate, pyruvic acid, lithocholic acid, 2-pyrocatechuic acid, and prostaglandin E1 were increased after alcohol administration, but the levels were recovered in treatment groups. The analysis indicated that ginger possesses hepatoprotective properties against AFLD. Furthermore, these metabolites can serve as early noninvasive candidate biomarkers in the clinical application of AFLD for health management.

Increased plasma corticosterone contributes to the development of alcoholic fatty liver in mice.

Ethanol ingestion increases endogenous glucocorticoid levels in both humans and rodents. The present study aimed to define a mechanistic link between the increased glucocorticoids and alcoholic fatty liver in mice. Plasma corticosterone levels were not affected in mice on a 2-wk ethanol diet regimen but significantly increased upon 4 wk of ethanol ingestion. Accordingly, hepatic triglyceride levels were not altered after 2 wk of ethanol ingestion but were elevated at 4 wk. Based on the observation that 2 wk of ethanol ingestion did not significantly increase endogenous corticosterone levels, we administered exogenous glucocorticoids along with the 2-wk ethanol treatment to determine whether the elevated glucocorticoid contributes to the development of alcoholic fatty liver. Mice were subjected to ethanol feeding for 2 wk with or without dexamethasone administration. Hepatic triglyceride contents were not affected by either ethanol or dexamethasone alone but were significantly increased by administration of both. Microarray and protein level analyses revealed two distinct changes in hepatic lipid metabolism in mice administered with both ethanol and dexamethasone: accelerated triglyceride synthesis by diacylglycerol O-acyltransferase 2 and suppressed fatty acid β-oxidation by long-chain acyl-CoA synthetase 1, carnitine palmitoyltransferase 1a, and acyl-CoA oxidase 1. A reduction of hepatic peroxisome proliferation activator receptor-α (PPAR-α) was associated with coadministration of ethanol and dexamethasone. These findings suggest that increased glucocorticoid levels may contribute to the development of alcoholic fatty liver, at least partially, through hepatic PPAR-α inactivation.

HIF-1α induction suppresses excessive lipid accumulation in alcoholic fatty liver in mice

Chronic alcohol intake stimulates hepatic oxygen consumption and subsequently causes liver hypoxia, leading to activation of hypoxia inducible factor-1 (HIF-1). Although HIF-1 plays a crucial role in the metabolic switch from aerobic to anaerobic metabolism in response to hypoxia, its roles in the regulation of lipid metabolism in alcoholic fatty liver remain unknown. Wild-type and hepatocyte-specific HIF-1α-null mice were subjected to a 6% ethanol-containing liquid diet for 4 weeks, and functional effects of loss of the HIF-1α gene on lipid metabolism were examined in the liver. Hepatocyte-specific HIF-1α-null mice developed severe hypertriglyceridemia with enhanced accumulation of lipids in the liver of mice exposed to a 6% ethanol-containing liquid diet for 4 weeks. Sterol regulatory element-binding protein 1c (SREBP-1c) and its downstream target acetyl-CoA carboxylase were greatly activated as the hepatic steatosis progressed, and these alterations were inversely correlated with the expression of the HIF-1-regulated gene DEC1. Overexpression of DEC1 in the mutant liver abrogated the detrimental effects of loss of HIF-1α gene on ethanol-induced fatty liver with reduced SREBP-1c expression. Conversely, co-administration of the HIF hydroxylase inhibitor dimethyloxalylglycine for the last 2 weeks improved markedly the ethanol-induced fatty liver in mice. The current results provide direct evidence for protective roles of HIF-1 induction in the development of ethanol-induced fatty liver via activation of the HIF-1-regulated transcriptional repressor DEC1.

Involvement of adiponectin-SIRT1-AMPK signaling in the protective action of rosiglitazone against alcoholic fatty liver in mice

The development of alcoholic fatty liver is associated with reduced adipocyte-derived adiponectin levels, decreased hepatic adiponectin receptors, and deranged hepatic adiponectin signaling in animals. Peroxisomal proliferator-activated receptor-gamma (PPAR-gamma) plays a key role in the regulation of adiponectin in adipose tissue. The aim of the present study was to test the ability of rosiglitazone, a known PPAR-gamma agonist, to reverse the inhibitory effects of ethanol on adiponectin expression and its hepatic signaling, and to attenuate alcoholic liver steatosis in mice. Mice were fed modified Lieber-DeCarli ethanol-containing liquid diets for 4 wk or pair-fed control diets. Four groups of mice were given a dose of either 3 or 10 mg.kg body wt(-1).day(-1) of rosiglitazone with or without ethanol in their diets for the last 2 wk of the feeding study. Coadministration of rosiglitazone and ethanol increased the expression and circulating levels of adiponectin and enhanced the expression of hepatic adiponectin receptors (AdipoRs) in mice. These increases correlated closely with the activation of a hepatic sirtuin 1 (SIRT1)-AMP-activated kinase (AMPK) signaling system. In concordance with stimulated SIRT1-AMPK signaling, rosiglitazone administration enhanced expression of fatty acid oxidation enzymes, normalized lipin 1 expression, and blocked elevated expression of genes encoding lipogenic enzymes which, in turn, led to increased fatty acid oxidation, reduced lipogenesis, and alleviation of steatosis in the livers of ethanol-fed mice. Enhanced hepatic adiponectin-SIRT1-AMPK signaling contributes, at least in part, to the protective action of rosiglitazone against alcoholic fatty liver in mice.

Mammalian Sirtuin 1 Is Involved in the Protective Action of Dietary Saturated Fat against Alcoholic Fatty Liver in Mice

This study was undertaken to elucidate the mechanism underling the protective effect of a high saturated fat (HSF) diet against the development of alcoholic fatty liver in mice. We tested the effects of a HSF diet on the ethanol-mediated increase in hepatic sterol regulatory element binding protein 1 (SREBP-1) activity. Thirty-two male mice were divided into 4 groups and fed liquid diets consisting of either a high polyunsaturated fat (40% of energy from corn oil) or a HSF (40% of energy from cocoa butter) diet with or without ethanol for 4 wk. In the ethanol-containing diets, ethanol was substituted for an equivalent amount of carbohydrate to provide 27.5% of the total energy. Control mice were pair-fed the same volume of liquid diets as the ethanol-fed mice. The HSF diet suppressed the increase in mature SREBP-1 protein and prevented increased mRNA of the SREBP-1-regulated lipogenic enzymes in the ethanol-fed mice (P < 0.05). Sirtuins 1 (SIRT1), a NAD+-dependent class III histone deacetylase, was upregulated by ethanol administration in mice fed the HSF diet (P < 0.05). The HSF diet blocked histone H3 at lysine 9 (lys9) hyperacetylation and attenuated association of acetylated histone H3-Lys9 with the promoters of mitochondrial glycerol-3-phosphate acyltransferase and stearoyl-CoA desaturase 1 in the livers of the ethanol-fed mice. These results suggest that the protective effects of HSF diet against the development of alcoholic liver steatosis may occur via regulation of the hepatic SIRT1-SREBP-1-histone H3 axis, suppressing the expression of genes encoding lipogenic enzymes and slowing the synthesis of hepatic fatty acids.

Effect of the Inducer of Interleukin‐6 (ME3738) on Rat Liver Treated With Ethanol

Recently, ME3738, a derivative of soyasapogenol B, was developed as an inducer of interleukin (IL)-6. It has been demonstrated that ME3738 is stimulate to produce IL-6 and that it protects against concanavalin A-induced liver failure. It has also been reported that IL-6 prevents alcoholic fatty liver in mice. These results suggest that ME3738 may prevent alcoholic liver injury. In the present study, we investigated whether ME3738 prevents fatty liver in ethanol-fed rats. Twenty-four male rats were fed with liquid diets containing ethanol or carbohydrates for 8 weeks. Liquid diets were prepared with or without ME3738 (0.8 mg/mL). Liver sections were stained for histology and IL-6 expression. Fatty changes of liver were classified into 4 grades: 0, 1+, 2+, and 3+. Plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), triglyceride, total cholesterol, and IL-6 were measured, as was hepatic ATP content. The extent of fatty degeneration in ethanol-fed rats was significantly greater (p=0.023) than that in controls. Fatty changes in rats fed ethanol containing ME3738 decreased, but were not significantly different from those in rats fed ethanol. Immunohistochemical staining of IL-6 was observed in perivenular hepatocytes of all rats, with its intensity becoming stronger in the order of controls, controls containing ME3738, ethanol, and ethanol-containing ME3738-fed rats. Plasma levels of AST and ALT in rats fed ethanol were significantly higher than those in controls. In rats fed ethanol-containing ME3738, these levels decreased to those of control-fed rats, but were not significantly different from those in rats fed ethanol. Plasma IL-6 was not detected in any rats. Hepatic ATP content in rats fed ethanol was significantly (p<0.05) lower than that in control-fed rats; however, in rats fed ethanol-containing ME3738, it increased to that in control-fed rats. Oral administration of ME3738, inducer of IL-6 may prevent the development of fatty liver caused by chronic ethanol consumption.