Hepatic Oxidation Research Articles

Low-ω3 Fatty Acid and Soy Protein Attenuate Alcohol-Induced Fatty Liver and Injury by Regulating the Opposing Lipid Oxidation and Lipogenic Signaling Pathways.

Chronic ethanol-induced downregulation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) and upregulation of peroxisome proliferator-activated receptor gamma coactivator 1-beta (PGC1β) affect hepatic lipid oxidation and lipogenesis, respectively, leading to fatty liver injury. Low-ω3 fatty acid (Low-ω3FA) that primarily regulates PGC1α and soy protein (SP) that seems to have its major regulatory effect on PGC1β were evaluated for their protective effects against ethanol-induced hepatosteatosis in rats fed with Lieber-deCarli control or ethanol liquid diets with high or low ω3FA fish oil and soy protein. Low-ω3FA and SP opposed the actions of chronic ethanol by reducing serum and liver lipids with concomitant decreased fatty liver. They also prevented the downregulation of hepatic Sirtuin 1 (SIRT1) and PGC1α and their target fatty acid oxidation pathway genes and attenuated the upregulation of hepatic PGC1β and sterol regulatory element-binding protein 1c (SREBP1c) and their target lipogenic pathway genes via the phosphorylation of 5′ adenosine monophosphate-activated protein kinase (AMPK). Thus, these two novel modulators attenuate ethanol-induced hepatosteatosis and consequent liver injury potentially by regulating the two opposing lipid oxidation and lipogenic pathways.

Duration of hexobarbital-induced sleep and monoamine oxidase activities in rat brain: Focus on the behavioral activity and on the free-radical oxidation.

The present study is focused on the relationship between monoamine oxidase (MAO) activity and hepatic content of cytochrome P450 (CYP), which reflects the status of microsomal oxidation. For vital integrative evaluation of hepatic microsomal oxidation in rats, the hexobarbital sleep test was used, and content of CYP was measured in hepatic microsomes. Rats with short hexobarbital sleep time (SHST) had higher content of microsomal CYP than rats with long hexobarbital sleep time (LHST). Whole brain MAO-A and MAO-B activities, serotonin and carbonylated protein levels were higher in SHST than in LHST rats. MAO-A and MAO-B activities were higher in brain cortex of SHST rats; MAO-A activity was higher only in hypothalamus and medulla of LHST. The same brain regions of LHST rats had higher concentrations of carbonylated proteins and lipid peroxidation products than in SHST rats. MAO activity was correlated with microsomal oxidation phenotype. Rats with higher hepatic content of CYP had higher activities of MAO-A and MAO-B in the brain and higher plasma serotonin levels than rats with lower microsomal oxidation. In conclusion, data obtained in this study showed a correlation between MAO activity and microsomal oxidation phenotype.

Digestibility of NDF and its effect on the level of rumen fermentation of carbohydrates

DOI: 10.15414/afz.2015.18.04.110–113 Received 14. July 2015 ǀ Accepted 12. October 2015 ǀ Available online 7. December 2015 The objective of this study, was to determinate the effects of digestibility of NDF of TMR on rumen fermentation characteristics and nutrient digestion, dairy cows were fed total mixed ration (TMR). We are measured NDF digestibility of TMR using in situ methods.Digestibility of NDF of TMR in our experiment range 26.8 to 48.2%. Digestibility of NDF of TMR did not alter VFA production but had effects on A/P ratio and production of acetate and propionate. Our results indicate that TMR with more dNDF may provide more favourable condition for nutrient digestion both in the rumen and in the total tract of dairy cows. Keywords : rumen, fermentation, NDF, volatile fatty acids, digestibility of NDF References ALLEN, M. S., BRADFORD, B. J. and OBA, M. (2009) BOARD-INVITED REVIEW: The hepatic oxidation theory of the control of feed intake and its application to ruminants. In J. Anim. Sci., vol. 87, no. 10, pp. 3317–3334. doi:http://dx.doi.org/10.2527/jas.2009-1779 BEEVER, D. E. and MOULD, F. L. (2000) Forage evaluation for efficient ruminant livestock production. In: D. I. Givens et al. (eds.) Forage Evaluation in Ruminant Nutrition. Wallington: CAB International. HOFFMAN, P.C. and SHAVER, R.D. (2009) UW-Feed Grain Evaluation System Marshfield Soil and Forage Analysis Laboratory. [Online] Available at: http://www.uwex.edu/ces/dairynutrition/documents/ WisconsinFGES.pdf. [Accessed? 2015-06-04]. HUTJENS, M. F. (2002) Is your TMR as good as it can be? In Hoard´s Dairyman, vol. 147, no. 18, pp. 698. CHUMPAWADEE, S. and PIMPA, O. (2009) Effect of fodder tree as fiber sources in total mixed ration on feed intake, nutrient digestibility, chewing behaviour and ruminal fermentation in beef cattle. In J. Anim. And Vet. Adv, vol. 8, no. 7, pp. 1279:1284. doi: http://dx.doi.org/2009.1279.1284 KOLVER, E. S. and DE VETH, M. J. (2002) Prediction of ruminal pH from pasture based diets. In J. Dairy Sci., vol. 85, no. 5, pp. 1255–1266. doi:http://dx.doi.org/10.3168/jds.S0022-0302 (02)74190-8 LINN, J.G. et al. (1989) Feeding the dairy herd. Madison: North Central Regional Extension. LOPEZ, S., J. DIJKSTRA, and FRANCE, J. (2000) Prediction of energy supply in ruminants, with emphasis on forages. In: D. I. Givens, E. Owens, R. F. E., Axford, and H. M. Omed, (eds.) Forage Evaluation in Ruminant Nutrition. Wallingford: CAB International, pp. 63-94. NRC (2001) Nutrient requirements of dairy cattle: Nutrient requirements of domestic animals. 7th revised edition. Washington: National Reserach Council. OBA, M. and ALLEN, M. S. (1999) Evaluation of the importance of the digestibility of neutral detergent fiber from forage: effects on dry matter intake and milk yield of dairy cows. In J. Dairy Sci., vol. 82, no. 3, pp. 589-596. doi:http://dx.doi.org/10.3168/jds.S0022-0302(99)75271-9 OBA, M. and ALLEN, M. S. (2000) Effects of brown midrib 3 mutation in corn silage on productivity of dairy cows fed two concentrations of dietary neutral detergent fiber: 3. Digestibility and microbial efficiency. In J. Dairy Sci., vol. 83, no. 6, pp. 1342–1349. doi: http://dx.doi.org/10.3168/jds.S0022-0302(00)75001-6 ORSKOV, E.R. and MCDONALD, I. (1979) The estimation of protein degradability in the rumen from incubation measurements weighed according to rate of passage. In J. Agric. Sci., vol. 92, no. 3, pp. 499-503. doi:http://dx.doi.org/10.1017/S0021859600063048 VARGA G.A. (2006) In vivo digestibility of forage. In: Proc. Tri-State dairy nutrition conference, Fort Wayne. Columbus: The Ohio State University, pp 95-106. VOELKER LINTON., J. A. and ALLEN, M. S. (2009) Nutrient demand interacts with forage family to affect N digestion and utilization responses in dairy cows. In J. Dairy Sci., vol. 92, no. 4, pp.1594-1602. doi:http://dx.doi.org/10.3168/jds.2008-1327

Resveratrol ameliorates hepatic steatosis and inflammation in methionine/choline-deficient diet-induced steatohepatitis through regulating autophagy.

BackgroundNon-alcoholic steatohepatitis (NASH) is one of the leading causes of chronic liver disease that can progress to liver fibrosis, cirrhosis and eventually hepatocellular carcinoma. Resveratrol, a naturally occurring phytoalexin, is believed to have therapeutic effects on hepatic steatosis. However, the effect of resveratrol on NASH and the underlying mechanism is not fully illustrated. In the present study, we aimed to exam the effect of resveratrol on methionine/choline-deficient (MCD) diet or medium-induced hepatic steatosis, oxidation and inflammation, and to explore the possible mechanism.MethodsC57BL/6 mice and AML12 cells were treated with MCD alone or in combination with different concentrations of resveratrol (100 mg/kg/day or 250 mg/kg/day for mice and 25 μmol/L, 50 μmol/L, or 100 μmol/L for cells). Levels of aminotransferases (ALT), interleukin 1β (IL-1β), IL-6, and tumor necrosis factor alpha (TNF-α) were measured, concentrations of triglyceride (TG) and thiobarbituric acid reactive substances (TBARs) were determined, and expressions of proteins involved in autophagy were analyzed.ResultsThe results indicate that MCD diet or medium induced NASH in mouse and AML12 cell, which was confirmed by the elevated levels of TG, TNF-α, IL-1β, IL-6, ALT and TBARS in mice serum or cell culture medium. Resveratrol administration slowed down NASH progression, decreased the levels of ALT, TG, TBARS, IL-1β, IL-6, downregulated mRNA expressions of TNF-α, IL-1β, IL-6, and regulated the expressions of proteins involved in autophagy, both in vitro and in vivo. However, an autophagical inhibitor significantly impaired the protective role of resveratrol on liver injury and inflammation.ConclusionsResveratrol can attenuate hepatic steatosis and inflammation in MCD-induced NASH by regulating autophagy. Thus, resveratrol may be a promising agent for inhibiting lipid accumulation and inflammatory processes associated with NASH.

3,5 Diiodo-L-Thyronine (T2) Does Not Prevent Hepatic Steatosis or Insulin Resistance in Fat-Fed Sprague Dawley Rats.

Thyroid hormone mimetics are alluring potential therapies for diseases like dyslipidemia, nonalcoholic fatty liver disease (NAFLD), and insulin resistance. Though diiodothyronines are thought inactive, pharmacologic treatment with 3,5- Diiodo-L-Thyronine (T2) reportedly reduces hepatic lipid content and improves glucose tolerance in fat-fed male rats. To test this, male Sprague Dawley rats fed a safflower-oil based high-fat diet were treated with T2 (0.25 mg/kg-d) or vehicle. Neither 10 nor 30 days of T2 treatment had an effect on weight, adiposity, plasma fatty acids, or hepatic steatosis. Insulin action was quantified in vivo by a hyperinsulinemic-euglycemic clamp. T2 did not alter fasting plasma glucose or insulin concentration. Basal endogenous glucose production (EGP) rate was unchanged. During the clamp, there was no difference in insulin stimulated whole body glucose disposal. Insulin suppressed EGP by 60% ± 10 in T2-treated rats as compared with 47% ± 4 suppression in the vehicle group (p = 0.32). This was associated with an improvement in hepatic insulin signaling; insulin stimulated Akt phosphorylation was ~2.5 fold greater in the T2-treated group as compared with the vehicle-treated group (p = 0.003). There was no change in expression of genes thought to mediate the effect of T2 on hepatic metabolism, including genes that regulate hepatic lipid oxidation (ppara, carnitine palmitoyltransferase 1a), genes that regulate hepatic fatty acid synthesis (srebp1c, acetyl coa carboxylase, fatty acid synthase), and genes involved in glycolysis and gluconeogenesis (L-pyruvate kinase, glucose 6 phosphatase). Therefore, in contrast with previous reports, in Sprague Dawley rats fed an unsaturated fat diet, T2 administration failed to improve NAFLD or whole body insulin sensitivity. Though there was a modest improvement in hepatic insulin signaling, this was not associated with significant differences in hepatic insulin action. Further study will be necessary before diiodothyronines can be considered an effective treatment for NAFLD and dyslipidemia.

Sex-Specific Differences in Hepatic Fat Oxidation and Synthesis May Explain the Higher Propensity for NAFLD in Men.

In most populations a greater proportion of men have hepatic steatosis than women. Sex-specific differences in hepatic dietary fatty acid (FA) metabolism have not been well characterized. We compared fasting and postprandial hepatic FA synthesis (de novo lipogenesis [DNL]) and oxidation in men and women. Fasting and postprandial hepatic FA metabolism was studied in 22 healthy men (n = 11) and women with similar age, body mass index, and liver fat content using metabolic substrates labeled with stable-isotope tracers ((2)H2O and [U(13)C]palmitate). Dietary FA oxidation was assessed by appearance of (13)C into plasma 3-hydroxybutyrate and breath CO2 as markers of liver and whole-body FA oxidation, respectively. Despite similar liver fat content, fasting and postprandial plasma triacylglycerol (TG) concentrations were significantly (P < .05) higher in men compared with women. The appearance of (13)C from dietary FA into plasma 3-hydroxybutyrate and breath CO2 was greater (P < .05) in women compared with men. Although the contribution of DNL into very low-density lipoprotein (VLDL)-TG was similar (∼ 10%) in the fasting state, there was a divergence in pattern over the course of the study, with men maintaining a higher contribution of DNL to VLDL-TG than women (P = .006 time x sex interaction). The combination of lower dietary FA oxidation and a prolonged increase in DNL observed in men may represent partitioning of FA into esterification and storage pathways within the liver, leading to greater VLDL-TG production, and predispose to the sex difference in hepatic steatosis.

The molecular mechanisms of liver and islets of Langerhans toxicity by benzene and its metabolite hydroquinone in vivo and in vitro

Benzene (C6H6) is one of the most commonly used industrial chemicals causing environmental pollution. This study aimed to examine the effect of benzene and its metabolite hydroquinone on glucose regulating organs, liver and pancreas, and to reveal the involved toxic mechanisms, in rats. In the in vivo part, benzene was dissolved in corn oil and administered through intragastric route at doses of 200, 400 and 800 mg/kg/day, for 4 weeks. And, in the in vitro part, toxic mechanisms responsible for weakening the antioxidant system in islets of Langerhans by hydroquinone at different concentrations (0.25, 0.5 and 1 mM), were revealed. Benzene exposure raised the activity of phosphoenolpyruvate carboxykinase (PEPCK), glucose 6-phosphatase (G6Pase) enzymes and increased fasting blood sugar (FBS) in comparison to control animals. Also, the activity of hepatic glucokinase (GK) was decreased significantly. Along with, a significant increase was observed in hepatic tumor necrosis factor (TNF-α) and plasma insulin in benzene treated rats. Moreover, benzene caused a significant rise in hepatic lipid peroxidation, DNA damage and oxidation of proteins. In islets of Langerhans, hydroquinone was found to decrease the capability of antioxidant system to fight free radicals. Also, the level of death proteases (caspase 3 and caspase 9) was found higher in hydroquinone exposed islets. The current study demonstrated that benzene and hydroquinone causes toxic effects on liver and pancreatic islets by causing oxidative impairment.

Naringenin prevents obesity, hepatic steatosis, and glucose intolerance in male mice independent of fibroblast growth factor 21.

The molecular mechanisms and metabolic pathways whereby the citrus flavonoid, naringenin, reduces dyslipidemia and improves glucose tolerance were investigated in C57BL6/J wild-type mice and fibroblast growth factor 21 (FGF21) null (Fgf21(-/-)) mice. FGF21 regulates energy homeostasis and the metabolic adaptation to fasting. One avenue of this regulation is through induction of peroxisome proliferator-activated receptor-γ coactivator-1α (Pgc1a), a regulator of hepatic fatty acid oxidation and ketogenesis. Because naringenin is a potent activator of hepatic FA oxidation, we hypothesized that induction of FGF21 might be an integral part of naringenin's mechanism of action. Furthermore, we predicted that FGF21 deficiency would potentiate high-fat diet (HFD)-induced metabolic dysregulation and compromise metabolic protection by naringenin. The absence of FGF21 exacerbated the response to a HFD. Interestingly, naringenin supplementation to the HFD robustly prevented obesity in both genotypes. Gene expression analysis suggested that naringenin was not primarily targeting fatty acid metabolism in white adipose tissue. Naringenin corrected hepatic triglyceride concentrations and normalized hepatic expression of Pgc1a, Cpt1a, and Srebf1c in both wild-type and Fgf21(-/-) mice. HFD-fed Fgf21(-/-) mice displayed greater muscle triglyceride deposition, hyperinsulinemia, and impaired glucose tolerance as compared with wild-type mice, confirming the role of FGF21 in insulin sensitivity; however, naringenin supplementation improved these metabolic parameters in both genotypes. We conclude that FGF21 deficiency exacerbates HFD-induced obesity, hepatic steatosis, and insulin resistance. Furthermore, FGF21 is not required for naringenin to protect mice from HFD-induced metabolic dysregulation. Collectively these studies support the concept that naringenin has potent lipid-lowering effects and may act as an insulin sensitizer in vivo.

Forced Hepatic Overexpression of CEACAM1 Curtails Diet-Induced Insulin Resistance.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) regulates insulin sensitivity by promoting hepatic insulin clearance. Liver-specific inactivation or global null-mutation of Ceacam1 impairs hepatic insulin extraction to cause chronic hyperinsulinemia, resulting in insulin resistance and visceral obesity. In this study we investigated whether diet-induced insulin resistance implicates changes in hepatic CEACAM1. We report that feeding C57/BL6J mice a high-fat diet reduced hepatic CEACAM1 levels by >50% beginning at 21 days, causing hyperinsulinemia, insulin resistance, and elevation in hepatic triacylglycerol content. Conversely, liver-specific inducible CEACAM1 expression prevented hyperinsulinemia and markedly limited insulin resistance and hepatic lipid accumulation that were induced by prolonged high-fat intake. This was partly mediated by increased hepatic β-fatty acid oxidation and energy expenditure. The data demonstrate that the high-fat diet reduced hepatic CEACAM1 expression and that overexpressing CEACAM1 in liver curtailed diet-induced metabolic abnormalities by protecting hepatic insulin clearance.

Metabolic Syndrome and Hepatic Steatosis is Reduced in C57BL/6J Mice Fed High‐fat Diets Supplemented with Soy Isoflavones

&lt;a name=“OLE_LINK14”&gt;&lt;/a&gt;&lt;a name=“OLE_LINK13”&gt;The effect of soy isoflavones on metabolic syndrome and hepatic lipid metabolism was investigated in male &lt;/a&gt;&lt;a name=“OLE_LINK41”&gt;&lt;/a&gt;&lt;a name=”OLE_LINK40”&gt;C57BL/6J&lt;/a&gt; mice fed a high‐fat diet (HF), and HF plus soy isoflavone supplement Novasoy (NS, 0.2%, w/w) diet for 10 weeks. Compared to HF, NS‐fed mice, despite no changes in food intake, had reduced percent weight gain over ten weeks (37±2.2% vs. 45±2.4%), reduced blood glucose levels (276±49 vs. 352±55 vs. mg/dL), reduced serum resistin (4.20±0.68 vs. 5.95±0.46 pg/mL), and reduced leptin (10.5 ±1.89 vs. 21.9±1.25 pg/mL (all p&lt;0.05). In addition, NS consumption prevented hepatic lipid accumulation as determined by histological analyses. Hepatic gene expression was measured and confirmed that intake of NS up‐regulated mRNA levels related to hepatic lipid oxidation, including ACOX‐1 and CPT1‐α. We followed these findings with an in vitro study in which HepG2 cells were induced to accumulate intracellular lipid by exposure to oleic acid followed by treatment with the isoflavone genistein. Genistein treatment at 5μmol/L ameliorated relative intracellular lipid accumulated as measured by oil red O staining (1.0 ± 0.09 vs. 0.85 ± 0.01, p&lt;0.05). We conclude that soy isoflavones have potential to act as an agent to ameliorate symptoms of metabolic syndrome and steatohepatitis.

ENOS Deficiency Increases Susceptibility to Western Diet Induced Hepatic Mitochondrial Dysfunction

Nitric oxide produced by endothelial nitric oxide synthase (eNOS) can influence mitochondrial biogenesis and electron transport chain activity. Hepatic mitochondrial dysfunction is a hallmark feature of nonalcoholic fatty liver disease (NAFLD), yet the underlying mechanisms remain elusive. Here, we tested the hypothesis that eNOS plays an important role in sustaining hepatic mitochondrial function in NAFLD. Wild‐type (WT) and eNOS knockout (eNOS‐/‐) mice received either control (CON; 10% fat, 3.5% sucrose) or a western diet high in fat (45%), sucrose (17%), and cholesterol (1%; HFC) for 18‐weeks. HFC diet feeding induced histological NAFLD and increased weight gain and % body fat in both genotypes compared to CON diet. Complete hepatic mitochondrial palmitate oxidation to CO2 was elevated in both eNOS‐/‐ groups compared with WT mice(p&lt;0.05), while incomplete acid‐soluble metabolite production was elevated only in eNOS‐/‐‐CON compared to other groups. In addition, maximal FCCP‐uncoupled mitochondrial respiration tended to be elevated in eNOS‐/‐‐CON compared to WT‐CON (+24%; p=0.08) but was significantly reduced with HFC feeding in eNOS‐/‐ mice (‐37% vs eNOS‐/‐‐CON; p&lt;0.05). Finally, HFC feeding dramatically reduced hepatic mRNA expression of the putative control for mitochondrial biogenesis, PGC‐1α, in WT (‐33%) and eNOS‐/‐ (‐58%) compared with WT‐CON (p&lt;0.05). These results support the hypothesis that eNOS limits susceptibility to western diet‐induced hepatic mitochondrial dysfunction and highlights a potential role for eNOS in hepatic mitochondrial biogenesis. Supported by:HL036088 (MHL) and VHA‐CDA2 1299‐03(RSR).

Decreased liver triglyceride content in adult rats exposed to protein restriction during gestation and lactation: role of hepatic triglyceride utilization.

We have previously demonstrated that protein restriction throughout gestation and lactation reduces liver triglyceride content in adult rat offspring. However, the mechanisms mediating the decrease in liver triglyceride content are not understood. The aim of the current study was to use a new group of pregnant animals and their offspring and determine the contribution of increased triglyceride utilization via the hepatic fatty-acid oxidation and triglyceride secretory pathways to the reduction in liver triglyceride content. Pregnant Sprague-Dawley rats received either a control or a low protein diet throughout pregnancy and lactation. Pups were weaned onto laboratory chow on day 28 and killed on day 65. Liver triglyceride content was reduced in male, but not female, low-protein offspring, both in the fed and fasted states. The reduction was accompanied by a trend towards higher liver carnitine palmitoyltransferase-1a activity, suggesting increased fatty-acid transport into the mitochondrial matrix. However, medium-chain acyl coenzyme A dehydrogenase activity within the mitochondrial matrix, expression of nuclear peroxisome proliferator activated receptor-α, and plasma levels of β-hydroxybutyrate were similar between low protein and control offspring, indicating a lack of change in fatty-acid oxidation. Hepatic triglyceride secretion, assessed by blocking peripheral triglyceride utilization and measuring serum triglyceride accumulation rate, and the activity of microsomal transfer protein, were similar between low protein and control offspring. Because enhanced triglyceride utilization is not a significant contributor, the decrease in liver triglyceride content in male low-protein offspring is likely due to alterations in liver fatty-acid transport or triglyceride biosynthesis.

Subchronic sleep restriction causes tissue-specific insulin resistance.

Short sleep duration is associated with an increased risk of type 2 diabetes. Subchronic sleep restriction (SR) causes insulin resistance, but the mechanisms and roles of specific tissues are unclear. The purpose of this article was to determine whether subchronic SR altered (1) hepatic insulin sensitivity, (2) peripheral insulin sensitivity, and (3) substrate utilization. This was a randomized crossover study in which 14 subjects underwent 2 admissions separated by a washout period. Each admission had 2 acclimatization nights followed by 5 nights of either SR (4 hours time in bed) or normal sleep (8 hours time in bed). MAIN OUTCOME MEASURE/METHODS: Insulin sensitivity (measured by hyperinsulinemic-euglycemic clamp) and hepatic insulin sensitivity (measured by stable isotope techniques) were measured. In addition, we assayed stress hormone (24-hour urine free cortisol, metanephrine, and normetanephrine), nonesterified fatty acid (NEFA), and β-hydroxybutyrate (β-OH butyrate) levels. Resting energy expenditure (REE) and respiratory quotient (RQ) were measured by indirect calorimetry. Compared to normal sleep, whole-body insulin sensitivity decreased by 25% (P = .008) with SR and peripheral insulin sensitivity decreased by 29% (P = .003). Whereas hepatic insulin sensitivity (endogenous glucose production) did not change significantly, percent gluconeogenesis increased (P = .03). Stress hormones increased modestly (cortisol by 21%, P = .04; metanephrine by 8%, P = .014; normetanephrine by 18%, P = .002). Fasting NEFA and β-OH butyrate levels increased substantially (62% and 55%, respectively). REE did not change (P = 0.98), but RQ decreased (0.81 ± .02 vs 0.75 ± 0.02, P = .045). Subchronic SR causes unique metabolic disturbances characterized by peripheral, but not hepatic, insulin resistance; this was associated with a robust increase in fasting NEFA levels (indicative of increased lipolysis), decreased RQ, and increased β-OH butyrate levels (indicative of whole-body and hepatic fat oxidation, respectively). We postulate that elevated NEFA levels are partially responsible for the decrease in peripheral sensitivity and modulation of hepatic metabolism (ie, increase in gluconeogenesis without increase in endogenous glucose production). Elevated cortisol and metanephrine levels may contribute to insulin resistance by increasing lipolysis and NEFA levels.

PPARα via HNF4α regulates the expression of genes encoding hepatic amino acid catabolizing enzymes to maintain metabolic homeostasis.

The liver is the main organ involved in the metabolism of amino acids (AA), which are oxidized by amino acid catabolizing enzymes (AACE). Peroxisome proliferator-activated receptor-α (PPARα) stimulates fatty acid β-oxidation, and there is evidence that it can modulate hepatic AA oxidation during the transition of energy fuels. To understand the role and mechanism of PPARα's regulation of AA catabolism, the metabolic and molecular adaptations of Ppara-null mice were studied. The role of PPARα on AA metabolism was examined by in vitro and in vivo studies. In wild-type and Ppara-null mice, fed increasing concentrations of the dietary protein/carbohydrate ratio, we measured metabolic parameters, and livers were analyzed by microarray analysis, histology and Western blot. Functional enrichment analysis, EMSA and gene reporter assays were performed. Ppara-null mice presented increased expression of AACE in liver affecting AA, lipid and carbohydrate metabolism. Ppara-null mice had increased glucagon/insulin ratio (7.2-fold), higher serum urea (73.1%), lower body protein content (19.7%) and decreased several serum AA in response to a high-protein/low-carbohydrate diet. A functional network of differentially expressed genes, suggested that changes in the expression of AACE were regulated by an interrelationship between PPARα and HNF4α. Our data indicated that the expression of AACE is down-regulated through PPARα by attenuating HNF4α transcriptional activity as observed in the serine dehydratase gene promoter. PPARα via HNF4α maintains body protein metabolic homeostasis by down-regulating genes involved in amino acid catabolism for preserving body nitrogen.

Translational research in complementary and alternative medicine 2014.

Translational research in complementary and alternative medicine 2014.

C5L2 Deficiency Enhances Development of Atherosclerosis in ApoE Knockout Mice

Background: The complement system is important in development of atherosclerosis via regulation of lipid and glucose metabolism as well as inflammation. Aim: The aim of the present study was to further analyze the contribution of C5L2 to the development of atherosclerosis. We proposed that, with DIO feeding, C5L2 deficiency would promote a phenotype that encourages atherosclerosis development. Coupled to ApoE deficiency, double knockout (2KO) mice would show exacerbated atherosclerotic plaque formation. Methods: First, Wildtype (WT) and C5L2-/-(C5L2KO) and subsequently, ApoE-/-(ApoEKO) and C5L2/ApoE double knockout mice were placed on diets inducing obesity (DIO) or standard chow diet for 12 - 15 weeks. Plasma lipids, glucose, cytokines and hepatic glycogen and lipid contents, mRNA levels and enzyme activities and atherosclerotic plaque size were measured. Results: C5L2KO had increased hepatic glucose oxidation (+90%, p < 0.001), reduced liver glycogen content on chow diet (-34%, p < 0.05) but increased with DIO (+51%, p < 0.05) vs WT. Glucose clearance was delayed in C5L2/ApoE-2KO vs ApoEKO mice with chow (p < 0.0001) and DIO diet (p = 0.0026). C5L2KO mice had increased hepatic lipid content and fatty acid synthesis but decreased lipid oxidation vs WT. Plasma cholesterol was further elevated in C5L2/ApoE-2KO vs ApoEKO with DIO feeding (p < 0.05). Hepatic cytokine expression was increased in C5L2KO mice compared to WT mice. Atherosclerotic plaque size was increased in C5L2/ ApoE-2KO mice compared with apoEKO on chow (p < 0.05) and DIO regimen (p < 0.001). Conclusions: C5L2 disruption worsens glucose and lipid metabolism, increases hepatic and circulating inflammation, and aggravates atherosclerosis.

Effect of Feeding Diets Combining Whole-Grain Paddy Rice and High Levels of Fat on Broiler Chicken Growth.

Previously, we showed that the growth of chicks fed a diet containing 43% whole-grain paddy rice and 10% soybean oil was retarded relative to a control group fed a corn-based diet containing 6% soybean oil. However, feeding chicks with 43% whole-grain paddy rice containing 6% soybean oil resulted in normal growth. It is possible that the observed growth retardation was caused by the high soybean oil content or resulted from the combination of whole-grain paddy rice and the high level of soybean oil which was added to the diet to maintain the overall energy content. The present study was therefore carried out to identify the reasons for the observed growth retardation. Thirty-six chicks (0-day-old) were divided into six equal-sized groups that were fed one of the following six experimental diets ad libitum for 28 d: two kinds of dehulled rice-based diets containing 5% or 10% soybean oil (DS5% or DS10%), another three whole-grain paddy rice-based diets containing 10% soybean oil, corn oil, or rendering oil (WS10%, WC10%, WR10%, respectively), and a WS10% diet supplemented with vitamin B12, methionine and ethoxyquin. The body weight gain of groups fed the WS10% and WC10% diets was significantly lower than the weight gain of birds fed the DS5% diet (control). In addition, the liver of birds fed the WS10% and WC10% diet exhibited significantly higher lipid peroxidation than that of the control group. In comparison, supplementation of the WS10% diet with vitamin B12, methionine and ethoxyquin dramatically improved growth and hepatic oxidation status. These results indicate that diets combining whole-grain paddy rice and high levels of soybean and corn oil adversely affect performance, presumably via lipid peroxidation in the liver.

Oral or intraperitoneal binge drinking and oxidative balance in adolescent rats.

Oxidative imbalance is one of the most important mechanisms of alcohol-induced injury. Acute alcohol exposure induces a significant amount of reactive oxygen species during its hepatic metabolism via the microsomal ethanol oxidizing system. During adolescence, the physiological development is still taking place; therefore, ethanol's effects differ in adolescents compared to that in adults. Because binge drinking is the most important model of ethanol intake used by adolescents and because little is known about its effects on the liver, we have used two routes of acute ethanol administration (oral and intraperitoneal) in adolescent rats in order to analyze the oxidative damage caused in the periphery and liver. Here, it has been demonstrated for the first time that binge drinking in adolescents causes peripheral oxidation of lipid and DNA as well as lipid and protein hepatic oxidation, which are related to lower glutathione peroxidise (GPx) activity, higher catalase (CAT) activity, and higher expression of NADPHoxidase, contributing to hepatic damage. In addition, it is shown that the intraperitoneal administration route results in increased oxidative damage, which is probably related to the resulting general stress response that causes higher DNA and protein oxidation due to higher NADPHoxidase expression and higher CAT and superoxide dismutase (SOD) activities. According to these results, it is concluded that binge drinking induces hepatic damage during adolescence, at least in part, as consequence of oxidative stress because the antioxidant response was insufficient to avoid liver oxidation. Alcohol administered intraperitoneally provoked more DNA oxidation than that from the oral alcohol exposure model.

MicroRNA 34a inhibits beige and brown fat formation in obesity in part by suppressing adipocyte fibroblast growth factor 21 signaling and SIRT1 function.

Brown fat generates heat through uncoupled respiration, protecting against hypothermia and obesity. Adult humans have brown fat, but the amounts and activities are substantially decreased in obesity, by unknown mechanisms. Here we show that elevated microRNA 34a (miR-34a) in obesity inhibits fat browning in part by suppressing the browning activators fibroblast growth factor 21 (FGF21) and SIRT1. Lentivirus-mediated downregulation of miR-34a in mice with diet-induced obesity reduced adiposity, improved serum profiles, increased the mitochondrial DNA copy number, and increased oxidative function in adipose tissue in both BALB/c and C57BL/6 mice. Remarkably, downregulation of miR-34a increased coexpression of the beige fat-specific marker CD137 and the browning marker UCP1 in all types of white fat, including visceral fat, and promoted additional browning in brown fat. Mechanistically, downregulation of miR-34a increased expression of the FGF21 receptor components, FGFR1 and βKL, and also that of SIRT1, resulting in FGF21/SIRT1-dependent deacetylation of PGC-1α and induction of the browning genes Ucp1, Pgc-1α, and Prdm16. Importantly, anti-miR-34a-mediated beneficial effects, including decreased adiposity, are likely from multiple tissues, since downregulation of miR-34a also improves hepatic FGF21 signaling and lipid oxidation. This study identifies miR-34a as an inhibitor of beige and brown fat formation, providing a potential target for treating obesity-related diseases.

Binding of polyunsaturated fatty acids to LXRα and modulation of SREBP‐1 interaction with a specific SCD1 promoter element

Stearoyl-CoA desaturase 1 (SCD1) is the rate limiting enzyme in unsaturated fatty acid biosynthesis. This enzyme has an important role in the regulation of hepatic lipogenesis and lipid oxidation, and alterations in these pathways may lead to several diseases. We examined, in HepG2 cell cultures, the mechanism of SCD1 regulation considering the involvement of two transcription factors: liver X receptor alpha (LXRα) and sterol regulatory element-binding protein-1 (SREBP-1), also investigating the effect of dietary polyunsaturated fatty acids (PUFAs) on this process. The analysis of SCD1 promoter allowed to identify a functional SREBP-1 binding site (SRE 1). LXRα activation increased SCD1 protein level through upregulation of SREBP-1 and its consequent binding to SRE 1 sequence. Polyunsaturated docosahexaenoic acid (DHA, C22:6), eicosapentaenoic acid (EPA, C20:5) and arachidonic acid (AA, C20:4) were able to reduce SREBP-1 binding to SCD1 promoter, while saturated stearic acid (SA, C18:0) did not give any effect. Surface plasmon resonance analysis showed a direct binding of DHA, EPA and AA to LXRα. These data indicate a direct inhibitory interaction of PUFAs with LXRα, a consequent reduction of SREBP-1 and of its binding to SCD1 promoter. This information provides a mechanism to explain the regulation of lipogenic pathways induced by PUFAs.