Increase In Hepatic Content Research Articles

Melatonin Mitigates the Progression of Chemically Induced Hepatocellular Carcinoma in Rats via Targeting Wnt/Β-Catenin Pathway, and Small Noncoding miR-let-7b.

Melatonin, the controlling hormone of the sleep-wake cycle, has acquired attention due to its role in immunomodulation, anti-inflammation, as well as its proapoptotic effects. Wnt/β-catenin signaling can modulate cancer progression by promoting cell division and migration, while miR-let-7b may inhibit cell growth, migration, and invasion by affecting the function of adaptive immune cells. This work was designed to detect the effect of using melatonin as an immunomodulating therapeutic approach to control the progression of chemically induced hepatocellular carcinoma (HCC). Thirty male rats were equally divided into control, HCC, and melatonin-HCC groups. Animals in the HCC and melatonin-HCC groups were injected with diethylnitrosamine (intraperitoneal single dose) followed by repeated carbon-tetrachloride subcutaneous injection once weekly for six weeks. Melatonin was given from the first week of the study and continued during the process of HCC induction. In the HCC group, the levels of tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF), and Wnt/β-catenin expression significantly increased, while there was a downregulation of microRNA Let7b. Melatonin administration reversed these changes, along with an increase in hepatic content of interleukin-2 (IL-2) and caspase-3. Melatonin exerted hepatic immunomodulating changes, in addition to proapoptotic and antiangiogenic effects, illustrated by increased IL-2, caspase-3, and decreased VEGF levels, respectively. Moreover, the use of melatonin during hepatocarcinogenesis positively modulated the disrupted expression of microRNA let7b and Wnt/β-catenin significantly.

Environmentally Relevant Hexavalent Chromium Disrupts Elemental Homeostasis and Induces Apoptosis in Zebrafish Liver

Although hexavalent chromium Cr [VI] is known as a toxicant in the aquatic environment, its effect in low, environmentally relevant concentration (ERC; 2mgL-1) is less characterized. Against this backdrop, the effects of Cr [VI] in ERC on zebrafish liver has been investigated in this study. Fluorescence microscopy and gel electrophoresis detected excess DNA damage and cell death via apoptosis in 2mgL-1 Cr [VI]-treated fish when compared with that of control. Besides, there were transcriptional activations of p53, Bax, Caspase 9 and Caspase 3 genes but downregulation of Bcl2 gene in the treated group, confirming the apoptotic pathway. Energy dispersive X-ray fluorescence (EDXRF) data showed significant (p < 0.05) increase in hepatic content of Cr, selenium, iron, manganese, calcium, sulfur and magnesium but depletion of zinc, copper and cobalt in the treated group. Collectively, the study shows that even a low, ERC of Cr [VI] is toxic to the zebrafish as it elicited marked apoptosis in the hepatocytes and altered the liver elemental profile.

Developmental changes in physiological amino acids and hepatic methionine remethylation enzyme activities in E10‐21 chick embryos and D1‐49 broilers

The remethylation of homocysteine to methionine is important for chick embryos to sustain the S-adenosylmethionine transmethylation reactions, which are essential for the rapid proliferation of cells. Developmental changes in hepatic 5-methyltetrahydrofolate-homocysteine methyltransferase (MFMT), betaine-homocysteine methyltransferase (BHMT) and hepatic serine hydroxymethyltransferase (SHMT) were determined in E10-21 Cobb 500 broiler chick embryos and hatched chicks from D1-49. Hepatic levels of free serine, glycine, putrescine, spermidine and spermine levels were also determined. Analyses showed hepatic MFMT-specific activity doubled from E10 to E12, with remaining embryo development experiencing small fluctuations in activity through E21. Hepatic MFMT doubled immediately after hatch, with peak activity occurring at D3. Afterwards, hepatic MFMT-specific activity steadily declined from D7-49. Hepatic BHMT activity was higher from E10 to E16 of embryogenesis, decreased rapidly at E17 and remained lower through E21 (p<.05). Hepatic BHMT-specific activity was also lower in chicks, with the exception of a peak in specific activity on D7. BHMT activity returned to lower levels by D21. Throughout embryogenesis, hepatic SHMT activity in chick embryos remained relatively constant except for a decrease at 13E, followed by an increase at 14E. Maximal activity of SHMT was found the first day post-hatch. Additionally, SHMT activity was significantly lower in growing chicks than that in embryos. Hepatic-free serine and glycine levels were negatively correlated with SHMT in hatched chicks. Hepatic polyamine, putrescine and spermidine shared a similar development pattern: peak level in the middle of incubation, low at late embryogenesis and lowest during the post-hatch period except an increase within one week after hatch. The sharp increase in hepatic concentrations of glycine, serine and putrescine, along with increased specific activities of MHMT, BHMT and SHMT from D1-7, suggests that methionine conservation (remethylation from homocysteine) and glycine/serine is critical for young chicks for organ growth, maturation, and development.

Different source of commercial vegetable oils may regulate metabolic, inflammatory and redox status in healthy rats

• The vegetable oils intake induces changes in metabolic and inflammatory parameters. • Coconut oil induces glycometabolic and hepatic alterations in healthy rats. • Linseed oil reduces serum TAG and IL-6. • Sunflower oil increases superoxide dismutase and catalase activity and reduces total glutathione, IL-6 e TNF. • Sunflower oil increases hepatic lipogenesis and reduces serum lipids. Our goal was to carry out a comparative study to evaluate the metabolic and inflammatory effects and the redox status of commercial vegetable oils supplementation [linseed (LO), coconut (VCO), and sunflower (SO)] in metabolically healthy rats. The results found in this study showed that the LO group decreased the HOMA-IR and hepatic cholesterol, and increased the serum levels of IL-6. Supplementation with VCO increased glucose and HOMA-IR, cholesterol concentration and serum triacylglycerol (TAG). In this group, there was also an increase in TBARS. In the SO group there was a decrease in serum concentrations of cholesterol and TAG and an increase in hepatic concentration of these lipids. In addition, in the SO group there was a decrease in hepatic and serum concentrations of IL-6 and hepatic levels of TNF, as well as a decrease in the GSH/GSSG ratio, suggesting changes in glutathione metabolism and inflammatory mediators.

Rapid increase in contaminant burdens following loss of body condition in canvasbacks (Aythya valisineria) overwintering on the Lake St. Clair region of the Great Lakes

Overwintering canvasbacks were collected in the Lake St. Clair region of the Great Lakes in the winter of 2008/09 and livers were analyzed for organochlorines, mercury (Hg), and selenium (Se). We found dramatic increases in hepatic concentrations of Hg, Se, sum PCBs, p,p’-DDE, and other organochlorines in canvasbacks in which concentrations in February were greater than concentrations in November when overwintering ducks arrived in the study area. Increases in contaminant burdens were generally greatest between December and January which also coincided with the period when ducks from Lake St. Clair (LSC) moved following freeze-up of the Lake to forage on the St. Clair River (SCR), an area of known historic contamination, and upstream of LSC. Body condition estimated using body metrics and measured using lipid reserves (after controlling for body size) increased in LSC ducks but subsequently decreased in SCR ducks. This rapid loss of body condition through loss of lipid reserves was one factor likely driving the dramatic increase in contaminant burdens and particularly for organochlorines which were inversely related to body condition in SCR ducks. Increased exposure due to foraging in closer proximity to contaminant sources and changes in diet associated with the movement of ducks may have also contributed to temporal trends. Concentrations overall were below those associated with toxicity with the exception of Se for which 30% of ducks exceeded the Se threshold that is considered elevated and one duck exceeded the threshold associated with possible toxicity. Fitness consequences of reduced lipid reserves include reduced survival, delayed migration, reduced breeding propensity, and transfer of contaminant burdens to eggs. Food availability, ice cover, and movements of canvasbacks are additional factors influencing contaminant accumulation and lipid reserves in waterfowl utilizing this important wintering location.

CYCLOPHOSPHAMIDE HEPATOTOXICITY: THE ROLE OF 4-HYDROXYNONENAL AND CYTOCHROME C OXIDASE AND THE POSSIBLE PROTECTIVE EFFECT OF GANODERMA LUCIDUM EXTRACT

Cyclophosphamide (CPA) is a widely used anti-neoplastic drug, but its usage is associated with several side effects including hepatotoxicity. This study was designed to evaluate the ameliorative effect of Ganoderma lucidium (GL) extract as a natural antioxidant against CPA hepatotoxicity in male Wistar albino rats. Four groups of rats (n = 7) were used in this study, Group I: served as a control group, group II: was administrated CPA (5 mg/kg), group III: received GL extract (50 mg/kg), and group IV: received CPA and GL extract at the same doses of groups II and III. All the treatments were orally administrated via gastric intubation for 21 consecutive days. Serum activities of the hepatic enzymes (AST, ALT and GGT) in addition to serum proteinogram were evaluated. Moreover, hepatic oxidant-antioxidant markers (4- hydroxynonenal (4-HNE), GSH, CAT and SOD) besides activity of cytochrome C oxidase enzyme were detected. Also, histopathological examination of the hepatic sections (H&amp;E stained) was performed. Serum activity of liver enzymes was elevated, proteinogram was disturbed in CPA-treated animals which accompanied by an increase in hepatic content of 4-HNE, depletion of hepatic antioxidant (GSH, CAT, SOD) and inhibition of hepatic cytochrome C oxidase activity, also hepatic histopathological disruptions were noticed in this group. All these hepatic disturbances were partially ameliorated upon co-administration of GL extract with CPA. In conclusion, production of 4- HNE and inhibition of cytochrome C oxidase enzyme may play a role in occurrence of CPA hepatotoxicity and GL extract may have an ameliorative role against this toxicity.Key words: cyclophosphamide; hepatotoxicity; Ganoderma lucidium; 4-hydroxynonenalon; cytochrome C oxidase

Dietary betaine activates hepatic VTGII expression in laying hens associated with hypomethylation of GR gene promoter and enhanced GR expression

BackgroundVitellogenin (VTG) is a precursor of egg yolk proteins synthesized within the liver of oviparous vertebrates. Betaine is an important methyl donor that is reported to improve egg production of laying hens with an unclear mechanism. In the present study, we fed betaine-supplemented diet (0.5%) to laying hens for 4 wk and investigated its effect on VTGII expression in the liver.ResultsBetaine did not affect chicken weight, but significantly (P < 0.05) increased egg laying rate accompanied with a significant (P < 0.05) increase in hepatic concentration and plasma level of VTGII. Plasma estrogen level did not change, but the hepatic expression of estrogen receptor α (ERα) mRNA was significantly (P < 0.05) up-regulated. Betaine did not affect the protein content of ERα, but significantly (P < 0.05) increased hepatic expression of glucocorticoid receptor (GR) at both mRNA and protein levels. Also, ERα/GR interaction tended to be enhanced in the liver nuclear lysates of betaine-supplemented hens as determined by co-immunoprecipitation. Furthermore, dietary betaine supplementation significantly increased (P < 0.05) the hepatic expression of methyl-transfer enzymes, such as BHMT, GNMT, and DNMT1, which was associated with higher SAM/SAH ratio and hypomethylation of GR promoter regions.ConclusionsBetaine activates hepatic VTGII expression in association with modified DNA methylation of GR gene promoter, GR expression and ERα/GR interaction. Activation of hepatic VTGII expression may contribute, at least partly, to improved egg production in betaine-supplemented hens.

Obesity exacerbates the acute metabolic side effects of olanzapine

Olanzapine is a second-generation antipsychotic used in the management of schizophrenia and various off-label conditions. The acute metabolic responses of olanzapine recapitulate many of the side effects associated with obesity. Obesity rates are high in the schizophrenic population, but it is unknown whether pre-existing obesity-associated metabolic dysfunction augments the acute side effects of olanzapine. To address this question, we compared the responses to olanzapine in lean and high-fat diet-induced (HFD) obese mice. Four weeks of HFD (60% kcal from fat) led to obese, hyperglycemic, and insulin resistant mice. Olanzapine-induced hyperglycemia and systemic insulin resistance were exacerbated in HFD-induced obese mice. Olanzapine also profoundly inhibited insulin signalling in skeletal muscle and liver, which appears to be exacerbated by obesity. The greater olanzapine-induced hyperglycemia may also result from increased hepatic glucose output in obese mice as pyruvate challenge led to significantly higher blood glucose concentrations, with associated increases in hepatic content of gluconeogenic enzymes. Olanzapine also suppressed RER while acutely increasing oxygen consumption in obese mice. A single olanzapine treatment reduced physical activity for up to 24 h, regardless of obesity. Considering obesity is very common in the schizophrenic population, these data suggest that previous research may be under-estimating the severity of olanzapine’s acute side effects.

Use of polychlorinated biphenyl and toxic equivalent concentrations in scat from mink(Neovison vison) fed fish from the upper Hudson River to predict dietary and hepatic concentrations and health effects.

To evaluate health effects associated with consumption of fish contaminated with polychlorinated biphenyls (PCBs) from the upper Hudson River, farm-raised mink were fed diets containing fish collected from the river. Endpoints assessed included adult reproductive performance, offspring growth and mortality, and organ mass and pathology of adults and their offspring. Scat samples were collected from adult males at the time of necropsy and from adult females just prior to whelping. Scat samples were analyzed for PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). The present study provides the results of these analyses and compares ∑PCB and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalent (TEQ) concentrations in scat with dietary and hepatic concentrations associated with effects reported previously. Dry weight concentrations of ∑PCBs and ∑TEQs in scat generally increased with dietary concentration and reflected corresponding increases in hepatic concentrations of ∑PCBs and ∑TEQs. Maternal concentrations of ∑PCBs in scat expressed on a dry, wet, and lipid weight basis predicted to result in 50% kit mortality (LC50) were 1.0, 0.30, and 12 μg ∑PCBs/g. Concentrations of ∑PCBs in scat expressed on a dry, wet, and lipid weight basis predicted to result in 50% incidence of a previously reported jaw lesion (EC50) were 1.7, 0.48, and 24 μg ∑PCBs/g in adult females and 2.5, 0.87, and 19 μg ∑PCBs/g in adult males. Environ Toxicol Chem 2018;37:563-575. © 2017 SETAC.

Involvement of the essential metal transporter Zip14 in hepatic Cd accumulation during inflammation

Upregulation of Zip14 contributes to hepatic zinc (Zn) and non-transferrin-bound iron (Fe) uptake during infection and inflammation. We investigated whether this essential metal transporter is also involved in hepatic cadmium (Cd) uptake under these conditions. An injection of lipopolysaccharide (LPS), turpentine oil (Tur) and n-hexane (Hex) resulted in an decrease in plasma Zn and Fe concentrations to 25–50% and an increase in hepatic concentrations of both metals to 150–200% of control mice. LPS significantly increased plasma interleukin (IL)-6 levels more rapidly than Tur or Hex. Tur or Hex significantly increased hepatic Zip14 mRNA expression and decreased ferroportin 1 mRNA expression following continuous increase of IL-6 level. Hepatic Cd and Zn concentrations increased significantly after repeated injections of Cd in Tur- or Hex-treated mice fed a control diet. Treatment with Tur or Hex additionally increased hepatic Cd accumulation in Zn-deficient mice, unlike in Fe-deficient mice. These results suggest that Zn transporters, such as Zip14, may be involved in hepatic Cd uptake during inflammation.

Gasoline effects on biotransformation and antioxidant defenses of the freshwater fish Prochilodus lineatus

Biochemical biomarkers in the Neotropical freshwater fish Prochilodus lineatus were evaluated following acute exposures to the water-soluble fraction of gasoline (WSFG). Fish were exposed to the WSFG diluted to 5% in water (WSFG group) or only to water (Control group) for 6, 24 and 96 h and the gills and liver were removed for the biochemical analyses. Fish exposed to WSFG for 24 and 96 h showed significant increase in the activity of 7-ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST) both in liver and gills, pointing toward phase I and phase II biotransformation of the compounds present in the WSFG. The results also indicated the activation of antioxidant defenses in both the liver and gills after fish exposure to WSFG. The liver showed activation of catalase (CAT) and glutathione peroxidase (GPx) after 96 h exposure. An increase in hepatic content of reduced glutathione (GSH) together with decreased glutathione reductase (GR) activity was observed after 24 and 96 h of exposure to WSFG. In the gills, only catalase (CAT) activity augmented after 6 and 24 h of exposure and GSH content increased after 24 h of WSFG exposure. However, in both the organs, activation of the antioxidant defenses was not enough to prevent oxidative damage since they showed lipid peroxidation (LPO) at one of the experimental times: the liver after 6 h and the gills only after 96 h of exposure to WSFG. This may indicate better adaptation of the liver to longer exposures, starting from 24 h. As the gills are the first organ to be exposed to xenobiotics, the antioxidant defenses were triggered immediately upon exposure to WSFG and were able to prevent the occurrence of LPO during the initial times.

Metallothionein Gene Expression in Liver of Rats Exposed to Cadmium and Supplemented with Zinc and Selenium

Cadmium (Cd), one of the most widely distributed heavy metals, is highly toxic to humans and animals. It is well known that zinc (Zn) and selenium (Se) administration reduce the Cd-induced toxicity and that metallothioneins can have a protective effect to mitigate Cd toxicity in biological systems. In this study we report the expression analysis of the two metallothioneines gene classes MT-1 and MT-2 as well as the total metalloprotein content in the liver of rats exposed to Cd (200 ppm), Cd + Zn (200 ppm + 500 ppm), Cd + Se (200 ppm + 0.1 ppm) or Cd + Zn + Se (200 ppm + 500 ppm + 0.1 ppm) in their drinking water for 35 days. Metals accumulation was quantified in rat liver. Cd decreased significantly the hepatic concentrations of Se and increased those of Zn. The treatment of Cd-exposed rats with Se alone or combined with Zn reversed the Cd-induced depletion of Se concentrations in the liver. However, Zn or Zn + Se administration significantly increased the liver Cd uptake and had no effect on the Cd-induced increase in hepatic concentrations of Zn. The molecular assay showed a decreasing trend of MT-1 relative gene expression levels in animals supplemented with Zn (6.87-fold), Se (3.58-fold), and their combination (1.69-fold) when compared to Cd-treated animals (16.22-fold). Upregulation of the MT-2 expression were recorded in all conditions, although fold induction levels were less pronounced than MT-1 expressions. Our data suggest that the well-established protective effect of Zn and Se against Cd-induced toxicity passes through non-MT gene expression mechanisms, being more dependent on the oxidative stress status of the cell.

Ethanol Self‐Administration and Alterations in the Livers of the Cynomolgus Monkey, Macaca fascicularis

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

Attenuated hepatic inflammation and fibrosis in angiotensin type 1a receptor deficient mice

Pharmacological blockade of the renin-angiotensin system (RAS) attenuates liver fibrogenesis in rats. Here, we provide genetic evidence implicating angiotensin type 1 (AT1) receptors in liver fibrogenesis. Wild type (WT) and AT1a knockout [AT1a (-/-)] mice were subjected to either sham operation or bile-duct ligation. Fibrosis was assessed by Sirius Red staining and hydroxyproline hepatic content. Fibrogenic and inflammatory cytokines were measured by ELISA. Bile duct ligation-induced elevation of serum liver enzymes was similar in WT and AT1a (-/-) mice. Bile duct ligated WT mice showed inflammatory changes and severe septal fibrosis. In contrast, AT1a (-/-) mice showed minor fibrotic lesions. Collagen accumulation was lower in AT1a (-/-) mice compared to WT mice. The increase in hepatic concentration of TGFbeta1 and pro-inflammatory cytokines was attenuated in AT1a (-/-) mice compared to WT mice. Immunohistochemistry analysis revealed decreased infiltration by inflammatory cells, lipid peroxidation products as well as decreased phosphorylation of c-Jun and p42/44 MAPK in AT1a (-/-) mice compared to AT1 (+/+) mice. AT1 receptors play an important role in the development of fibrosis. Pharmacological blockade of AT1 receptors appears to be a promising approach to treat liver fibrosis.

Effects of methanol extract of Cirsium japonicum var. ussuriense and its principle, hispidulin-7-O-neohesperidoside on hepatic alcohol-metabolizing enzymes and lipid peroxidation in ethanol-treated rats.

Effects of the methanol extract of Cirsium japonicum var. ussuriense and hispidulin 7-O-neohesperidoside isolated from the plant on hepatic alcohol-metabolizing enzymes and lipid peroxidation were studied in rats treated with ethanol. Rats treated with 10% alcohol solution for 6 weeks were orally administered with 250 or 500 mg of methanol extract or 10 or 20 mg of hispidulin 7-O-neohesperidoside per kg body weight daily during the last week of ethanol treatment. The administration of the methanol extract of herbal plant and hispidulin 7-O-neohesperidoside in ethanol-treated rats significantly enhanced the activities of hepatic alcohol dehydrogenase, microsomal ethanol-oxidizing system and aldehyde dehydrogenase in a dose-dependent manner. The extract and the compound decreased hepatic lipid peroxidation along with an increase in hepatic content of reduced glutathione. The methanol extract and hispidulin 7-O-neohesperidoside of C. japonicum var. ussuriense also increased the activity of glutathione reductase, but had no effect on gamma-glutamylcysteine synthase. The results suggest that C. japonicum var. ussuriense may alleviate alcoholic toxicity by enhancing ethanol oxidation as well as inhibiting lipid peroxidation, and hispidulin 7-O-neohesperidoside is one of the active substances responsible for the protective effects of this plant.

FXR-mediated down-regulation of CYP7A1 dominates LXRα in long-term cholesterol-fed NZW rabbits

We investigated how cholesterol feeding regulates cholesterol 7alpha-hydroxylase (CYP7A1) via the nuclear receptors farnesoid X receptor (FXR) and liver X receptor alpha (LXRalpha) in New Zealand white rabbits. After 1 day of 2% cholesterol feeding, when the bile acid pool size had not expanded, mRNA levels of the FXR target genes short-heterodimer partner (SHP) and sterol 12alpha-hydroxylase (CYP8B) were unchanged, indicating that FXR activation remained constant. In contrast, the mRNA levels of the LXRalpha target genes ATP binding cassette transporter A1 (ABCA1) and cholesteryl ester transfer protein (CETP) increased 5-fold and 2.3-fold, respectively, associated with significant increases in hepatic concentrations of oxysterols. Activity and mRNA levels of CYP7A1 increased 2.4 times and 2.2 times, respectively. After 10 days of cholesterol feeding, the bile acid pool size increased nearly 2-fold. SHP mRNA levels increased 4.1-fold while CYP8B declined 64%. ABCA1 mRNA rose 8-fold and CETP mRNA remained elevated. Activity and mRNA of CYP7A1 decreased 60% and 90%, respectively. Feeding cholesterol for 1 day did not enlarge the ligand pool size or change FXR activation, while LXRalpha was activated highly secondary to increased hepatic oxysterols. As a result, CYP7A1 was up-regulated. After 10 days of cholesterol feeding, the bile acid (FXR ligand) pool size increased, which activated FXR and inhibited CYP7A1 despite continued activation of LXRalpha. Thus, in rabbits, when FXR and LXRalpha are activated simultaneously, the inhibitory effect of FXR overrides the stimulatory effect of LXRalpha to suppress CYP7A1 mRNA expression.

Effects of dietary carbohydrate and myo-inositol on metabolic changes in rats fed 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane (DDT)

This study was conducted to examine the effects of dietary carbohydrate [starch or sucrose (500g/kg diet)] and myo-inositol (2g/kg diet) on metabolic changes in rats fed 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane (DDT) (0.7g/kg diet). Dietary DDT enhanced serum and hepatic lipids and hepatic thiobarbituric acid reactive substances (TBA-RS), elevated hepatic activities of lipogenic enzymes such as malic enzyme (ME), glucose-6-phosphate dehydrogenase (G6PD) and fatty acid synthetase (FAS), increased hepatic cytochrome P-450 content and the activities of drug-metabolizing enzymes such as aminopyrine N-demethylase, glutathione S-transferase and 4-nitrophenol-UDP glucuronosyltransferase (4NP-UDPGT) and raised hepatic ascorbic acid and serum copper. Dietary sucrose promoted the increases in hepatic concentrations of total lipids, triglyceride and cholesterol, hepatic activity of ME, hepatic TBA-RS, cytochrome P-450 content and serum copper due to DDT feeding when compared to DDT administered in a starch based diet. Dietary myo-inositol significantly depressed the rises in hepatic concentrations of total lipids, triglyceride and cholesterol and the activities of ME and G6PD due to DDT feeding regardless of dietary carbohydrate quality. Dietary starch supplemented with myo-inositol potentiated the enhancements in hepatic activities of Phase II drug-metabolizing enzymes such as glutathione S-transferase and 4NP-UDPGT due to DDT feeding. These results suggest that dietary starch and myo-inositol can protect DDT fed rats against an accumulation of hepatic lipids, which might be mainly ascribed to the depression of hepatic lipogenesis. In addition, the present study implies that the supplementation of myo-inositol to high starch diet might improve the function of drug-metabolizing enzymes exposed to DDT.

Alcohol exposure and paracetamol-induced hepatotoxicity.

Most instances of hepatotoxicity due to paracetamol in the United Kingdom and Australia are the result of large overdoses of the drug taken with suicidal or parasuicidal intent. In contrast, serious hepatotoxicity at recommended or near-recommended doses for therapeutic purposes has been reported, mainly from the United States and in association with chronic alcohol use, leading to the widely held belief that chronic alcoholics are predisposed to paracetamol-related toxicity at relatively low doses. Yet the effects of alcohol on paracetamol metabolism are complex. Studies performed in both experimental animals and humans indicate that chronic alcohol use leads to a short-term, two- to threefold increase in hepatic content of cytochrome P4502E1, the major isoform responsible for the generation of the toxic metabolite from paracetamol, although increased oxidative metabolism of paracetamol at recommended doses has not been demonstrated clinically. A reduced hepatic content of glutathione, required to detoxify the reactive metabolite, has been documented in chronic alcoholics, due probably to associated fasting and malnutrition, providing a metabolic basis for any possible predisposition of this group to hepatotoxicity at relatively low paracetamol doses. Simultaneous alcohol and paracetamol ingestion reduces oxidative metabolism of paracetamol in both rodents and humans, predominantly as a consequence of depletion in cytosol of free NADPH. The possibilities that chronic alcohol use may predispose to paracetamol-related hepatotoxicity and that alcohol taken with paracetamol may protect against it, based on these metabolic observations, are examined in this review.

Effects of Perfluorooctanoic Acid on the Synthesis of Phospholipids in the Liver of Mice Fed a Dietary Soybean Oil, Perilla Oil or Fish Oil.

The effects of perfluorooctanoic acid (PFOA) on the synthesis of phospholipids were studied in combination with feeding of various dietary oils (soybean oil (SO), perilla oil (PO) or fish oil (FO)). Hepatic contents of phosphatidylcholine (PtdCho), phosphatidylethanolamine (PtdEtn) and phosphatidylinositol (PtdIns) did not differ between the three dietary groups except for a high level of PtdEtn in FO-fed mice. PFOA treatment increased the hepatic content of PtdCho and PtdEtn by 1.5 fold but did not affect that of PtdIns. Fatty acid compositions of phospholipids were different between the three groups reflecting the fatty acid composition in their diet. The rate of incorporation of [3H]glycerol into PtdEtn in the FO-fed group was significantly higher and that into TG was lower, compared to other dietary groups in PFOA-untreated mice. PFOA treatment significantly increased the incorporation of [3H]glycerol into PtdEtn and PtdSer and decreased that into TG, whereas those into other lipid classes were not altered by PFOA treatment. These results suggest that acceleration of PtdEtn synthesis de novo is responsible for a marked increase in the hepatic content of PtdEtn in PFOA-treated mice, whereas an increase in hepatic content of PtdCho is thought not to be due to increased synthesis de novo.

CYP2E1 and CYP4A as microsomal catalysts of lipid peroxides in murine nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) and alcoholic liver disease have similar pathological features. Because CYP2E1 plays a key role in alcoholic liver disease with its ability to stimulate lipid peroxidation, we tested the proposal that CYP2E1 could also be a factor in the development of NASH. In a dietary model - mice fed a methionine- and choline-deficient (MCD) diet - liver injury was associated with both induction of CYP2E1 and a 100-fold increase in hepatic content of lipid peroxides. Microsomal NADPH-dependent lipid oxidases contributed to the formation of these lipid peroxides, and in vitro inhibition studies demonstrated that CYP2E1 was the major catalyst. To further define the role of CYP2E1 as an initiator of oxidative stress in NASH, Cyp2e1(-/-)mice were administered the MCD diet. CYP2E1 deficiency neither prevented the development of NASH nor abrogated the increased microsomal NADPH-dependent lipid peroxidation, indicating the operation of a non-CYP2E1 peroxidase pathway. In Cyp2e1(-/-) mice with NASH (but not in wild-type mice), CYP4A10 and CYP4A14 were upregulated. Furthermore, hepatic microsomal lipid peroxidation was substantially inhibited by anti-mouse CYP4A10 antibody in vitro. These results show that experimental NASH is strongly associated with hepatic microsomal lipid peroxidation. CYP2E1, the main enzyme associated with that process in wild-type mice, is not unique among P450 proteins in catalyzing peroxidation of endogenous lipids. We have now identified CYP4A enzymes as alternative initiators of oxidative stress in the liver.