Hepatic Triacylglycerol Levels Research Articles

FXR Antagonist FLG249 Lowers Hepatic Triacylglycerol and Serum Cholesterol Level in High-Fat Diet-Induced Obese Mice.

Farnesoid X receptor (FXR) is a nuclear receptor that regulates the synthesis and enterohepatic circulation of bile acids (BAs). It also regulates lipid and carbohydrate metabolism, making FXR ligands potential therapeutic agents for systemic and/or hepatic metabolic disorders. We previously synthesized a series of FXR antagonists and showed that oral administration of FLG249 reduced the expression of several FXR target genes in the mouse ileum. Here, we investigated the effects of FLG249 on lipid metabolism in mice fed a high-fat diet (HFD). When FLG249 was administered for 4 weeks to HFD-induced obese mice, it altered the expression of genes related to BA metabolism, ceramide synthesis and fatty acid β-oxidation, improving lipid metabolism in the liver and ileum without decreasing body weight. These findings suggest that FLG249 has the potential to be a low toxicity pharmaceutical compound and likely acts as a nonsteroidal FXR antagonist to improve lipid metabolism disorders.

Metformin Lowers Plasma Triacylglycerol Levels in Mice with Impaired Carnitine Biosynthesis and Fatty Liver

The antidiabetic drug metformin has a wide range of metabolic effects and may also reduce the risk of obesity-related diseases. The aim of the current study was to investigate if metformin could counteract meldonium-induced fatty liver. Four groups of male C57BL/6J mice were fed a low-fat control diet, or low-fat diets supplemented with metformin, meldonium, or metformin and meldonium for three weeks. Meldonium treatment led to 5.2-fold higher hepatic triacylglycerol (TAG) levels compared to control, and metformin lowered the meldonium-induced lipid accumulation insignificantly by 21%. Mice treated with metformin and meldonium demonstrated significantly lower weight gain, visceral adipose tissue weight and plasma levels of TAG compared to meldonium alone. The hepatic mRNA level of carnitine palmitoyl transferase 1 was increased 2-fold with combined meldonium and metformin treatment compared to meldonium treatment (p < 0.001). Increased hepatic expression of genes involved in fatty acid oxidation and lipid transport was observed in the combination group compared to control, and increased gene expression of the mitochondrial uncoupling protein UCP2 was observed compared to the meldonium group. In addition, the product of fatty acid oxidation, acetylcarnitine, increased in plasma in metformin-treated mice. Altogether, metformin treatment influenced hepatic lipid metabolism and lowered plasma TAG in meldonium-induced fatty liver in mice.

Combining albumin deficiency and acute exercise reduces hepatic lipid droplet size in mice

Hepatic lipid droplets (LDs) are implicated in ectopic lipid accumulation. The core of LDs, triacylglycerol (TAG), is synthesized from the esterification of fatty acids to a glycerol-3-phosphate (G-3-P) backbone. Albumin transports plasma free fatty acids, and previously albumin knockout (Alb−/−) mice were shown to exhibit lower hepatic TAG levels than wildtype (WT). Exercise is a beneficial strategy to alter hepatic metabolism, but its impacts on reducing hepatic lipids are far from satisfactory. The aim of this study was to investigate the combined effect of albumin deficiency and acute exercise on hepatic LDs. Eight-week-old male Alb−/− and WT mice were divided into sedentary and exercise groups. Exercised mice performed a 30-min high-intensity exercise bout. Results showed that sedentary Alb−/− mice had smaller hepatic LDs (P < 0.0001), associated with mitochondria, while WT mice exhibited larger LDs, surrounded by glycogen granules. Following acute exercise, hepatic LDs in Alb−/− mice reduced by 40% in size, while in WT increased by 14% (P < 0.0001). The maintenance of WT hepatic LDs was associated with elevated G-3-P level (P < 0.05), potentially derived from glycogen (R = -0.32, %change in glycogen versus LD content, P < 0.05). The reduction in Alb−/− mice LDs after exercise was possibly due to their low glycogen level. In conclusion, Alb−/− mice exhibited an enhanced capacity for reducing hepatic LD size and content in response to exercise. These findings suggest that modulating albumin’s functions combined with exercise could be a potential strategy to reduce ectopic lipid deposition in the liver.

Ingesting a fermented milk product reduces liver triacylglycerol accumulation and normalizes gut permeability in rats even under a cholic acid-fed condition

We investigated whether a diet containing fermented milk products (FMP) improves hepatic lipid accumulation and gut permeability induced by cholic acid (CA) supplementation. After acclimation, male Slc:Wistar rats were fed diets supplemented with a combination of FMP and/or CA (0.5 g/kg diet) for four weeks. FMP was used as a protein source. The FMP-containing diet reduced the total food intake and hepatic triacylglycerol levels without altering the body weight. Enhanced in vivo gut permeability induced by CA was inhibited by the FMP diet. The FMP diet also enhanced the excretion of fecal triacylglycerol and the fecal concentration of non-12-hydroxylated BAs. Multiple regression analysis revealed that total food intake, fecal deoxycholic acid concentration, and fecal triacylglycerol excretion were predictors of hepatic triacylglycerol concentration. A negative correlation was observed between fecal non-12-hydroxylated BAs and hepatic triacylglycerol concentration. These results imply that FMP contributes to reduced hepatic lipid accumulation and normalised gut permeability.

Treatment with Interleukin-25 Suppresses Short-Term High-Fructose Diet-Induced Hepatic Gene Expression and Activities of Fatty Acid Synthesis Enzymes in Rats.

This study aimed to investigate the effects of interleukin-25, which belongs to the interleukin-17 family, on short-term high-fructose diet-induced hepatic triacylglycerol accumulation. Rats were fed a high-starch (control) or high-fructose diet for 7 d, with or without intraperitoneal administration of recombinant interleukin-25 from days 3-7. Treatment with interleukin-25 significantly reduced the mRNA levels and activity of fatty acid synthesis enzymes and caused a nominal reduction in hepatic triacylglycerol levels in rats fed a high-fructose diet but not in those fed a control diet. Interleukin-25 treatment did not affect the mRNA levels of β-oxidation enzymes in either the control or fructose-fed rats. These results suggest that treatment with interleukin-25 suppresses short-term high-fructose diet-induced fatty acid synthesis and leads to the alleviation of triacylglycerol accumulation in the liver.

Hawthorn total flavonoids ameliorate ambient fine particulate matter-induced insulin resistance and metabolic abnormalities of lipids in mice

Recent studies have shown a strong correlation between ambient fine particulate matter (PM2.5) exposure and diabetes risk, including abnormal lipid accumulation and systemic insulin resistance (IR). Hawthorn total flavonoids (HF) are the main groups of active substances in Hawthorn, which showed anti-hyperlipidemic and anti-hyperglycemic effects. Therefore, we hypothesized that HF may attenuate PM2.5-induced IR and abnormal lipid accumulation. Female C57BL/6 N mice were randomly assigned to the filtered air exposure (FA) group, concentrated PM2.5 exposure (PM) group, PM2.5 exposure maintained on a low-dose HF diet (LHF) group, and PM2.5 exposure maintained on a high-dose HF diet (HHF) group for an 8-week PM2.5 exposure using a whole-body exposure device. Body glucose homeostasis, lipid profiles in the liver and serum, and enzymes responsible for hepatic lipid metabolism were measured. We found that exposure to PM2.5 impaired glucose tolerance and insulin sensitivity. In addition, triacylglycerol (TAG) in serum elevated, whereas hepatic TAG levels were decreased after PM2.5 exposure, accompanied by inhibited fatty acid uptake, lipogenesis, and lipolysis in the liver. HF administration, on the other hand, balanced the hepatic TAG levels by increasing fatty acid uptake and decreasing lipid export, leading to alleviated systemic IR and hyperlipidemia in PM2.5-exposed mice. Therefore, HF administration may be an effective strategy to protect against PM2.5-induced IR and metabolic abnormalities of lipids.

Early- and whole-life exposures to florfenicol disrupts lipid metabolism and induces obesogenic effects in zebrafish (Danio rerio)

Florfenicol (FF), a widely used veterinary antibiotic, has been frequently detected in both aquatic environments and human body fluids. As a result, there is a growing concern on its health risks. Previous studies have revealed various toxicities of FF on animals, while there are relatively limited researches on its metabolic toxicity. Herein, by employing zebrafish as an in vivo model, endpoints at multiple levels of biological organization were measured to investigate the metabolic toxicity, especially disturbances on lipid metabolism, of this emerging pollutant. Our results indicated that early-life exposure (from 2 h past fertilization (hpf) to 15 days past fertilization (dpf)) to FF significantly increased body mass index (BMI) values, staining areas of visceral lipids, and triacylglycerol (TAG) and total cholesterol (TC) contents of larvae. Further, by analyzing expression patterns of genes encoding key proteins regulating lipid metabolism, our data suggested that promoted intestinal absorption and hepatic de novo synthesis of lipids, suppressed TAG decomposition, and inhibited FFA oxidation all contributed to TAG accumulation in larvae. Following whole-life exposure (from 2 hpf to 120 dpf), BMI values, TAG and TC contents all increased significantly in males, and significant increases of hepatic TAG levels were also observed in females. Moreover, FF exposure interfered with lipid homeostasis of males and females in a gender-specific pattern. Our study revealed the obesogenic effects of FF at environmentally relevant concentrations (1, 10, and 100 μg/L) and therefore will benefit assessment of its health risks. Additionally, our results showed that FF exposure caused a more pronounced obesogenic effect in zebrafish larvae than adults, as suggested by significant increases of all endpoints at individual, tissular, and molecular levels in larvae. Therefore, our study also advances the application of zebrafish larval model in assessing metabolic toxicity of chemicals, due to the higher susceptibility of larvae than adults.

Changes in CD and Correlation with Hepatic Insulin Resistance Index and Triacylglycerol 36 Level in Liver of Malarial Infected Mice Treated with Phyllanthus amarus

Phyllanthus amarus is an herb for the treatment of various ailments including malaria. Its antiplasmodial properties and antioxidant capacity have been reported, but very little is known about its effect on CD36 in relation to hepatic insulin resistance and triacylglycerol level. Hence, this study was undertaken to evaluate the changes in soluble CD36 concentrations and correlation with hepatic insulin resistance index and triacylglycerol levels in liver of Plasmodium berghei malarial parasite infected mice treated with graded doses of Phyllanthus amarus ethanolic leaf extract. Thirty (30) adult Swiss albino mice of both sexes weighing between 20-30g were assigned into six (6) groups (n=5/grp). Crude ethanolic leaf extract of Phyllanthus amarus was administered at 150, 300 and 450mg/kg/d as single daily dose for 7 days. On the 8th day of study, the mice were sacrificed under chloroform anaesthesia after an overnight fast. Blood sample was collected by cardiac puncture and centrifuged to obtain serum which was used for the assay of serum CD36, glucose and insulin, while, liver of each mouse was excised and processed for the assay of varying doses (150, 300 and 450mg/kg/d) of Phyllanthus amarus crude ethanolic leaf extract to experimental mice infected with P. berghei malarial parasite for seven days maintained serum soluble CD36 (3.40±0.52pg/ml, 3.47±0.46pg/ml and 3.37±0.46pg/ml), hepatic insulin resistance index (0.85±0.10, 0.77±0.17 and 0.82±0.13) and liver triacylglycerol (134.33±15.95mg/dl, 174.00±11.27mg/dl and 163.67±11.02mg/dl) levels, respectively, in trends that compared well with the Control and chloroquine – treated data ( C D 3 6 = 3.03±0.12pg/ml, liver TAG = 139.33±12.01, HIR index = 0.64±0.07). Correlation of CD36 with liver triacylglycerol for the malarial infected group without treatment was strongly positive, while, that with hepatic insulin resistance index was strongly negative. The control and chloroquine treated groups produced similar correlation pattern, but those for the extract-treated were weaker. Malarial infection in experimental mice significantly (p&lt;0.05) increased serum soluble CD36 and this impacted HIR index and liver TAG. However, extract and chloroquine treatments ameliorated the malaria-induced level of serum soluble CD36 and hepatic triacylglycerol, using documented methods. Results indicate that infection of mice with Plasmodium berghei malarial parasite yielded significant increase in level of CD36 (5.40±0.70pg/ml) and liver triacylglycerol, TAG (259.00±7.21mg/dl), but abnormal reduced (p&lt;0.05) hepatic insulin resistance, HIR index (0.37±0.05) when compared with the control mice (CD36 = 3.47±0.46pg/ml, liver TAG = 161.00±10.00, HIR index = 0.68±0.18) at the 5% probability level. However, administration of as starting materials for drugs (Sofowora, 1993). Plants have provided an alternative strategy in research for new drugs. It is likely that plants will continue to be a valuable source of new molecules which may after possible chemical manipulations provide new and improved drugs (Shan et al., 2006). One of such plants is Phyllanthus amarus.Phyllanthus amarus belongs to the family Euphorbiaceae (the spurge family) from which the largest genus is the Euphorbia. It has about eight hundred (800) species which are found in tropical and subtropical countries of the world (Mazumder et al., 2005). Phytochemicals identified in the leaf extract include alkaloids, flavonoids, tannins, saponins, anthraquinone and glycosides (Onyesom et al., 2015). The antimalarial activity of P. amarus has been observed (Onyesom and Adu, 2015). Malaria is a mosquito borne infectious disease of humans caused by eukaryotic protists of the genus Plasmodium. It is widespread in tropical and subtropical regions of the world including much of the sub-Saharan Africa. In Nigeria, malaria is mostly caused by Plasmodium falciparum. The association with HIR index and liver TAG in manners that were similar to the control trend.

Upregulation of 4-Hydroxynonenal Contributes to the Negative Effect of n-6 Polyunsaturated Fatty Acid on Alcohol-Induced Liver Injury and Hepatic Steatosis.

The present study aimed to investigate the effects of saturated fatty acids (SFA) and n-6 polyunsaturated fatty acids (PUFA) on alcoholic liver disease (ALD) and the underlying mechanisms. C57BL/6J male mice were randomly fed a corn oil or palm oil diet (rich in n-6 PUFA and SFA, respectively) with or without ethanol for four weeks (n = 10/group). A series of experiments in vitro with AML-12 hepatocyte were conducted to better elucidate the potential mechanisms underlying the phenomenon observed in animals. Compared with palm oil, corn oil aggravated alcohol-induced liver injury and hepatic steatosis, indicated by a histological analysis and significant elevations of plasma alanine aminotransferase and hepatic triacylglycerol (TG) level. Apoptosis-associated proteins in the ASK1-JNK pathway were significantly enhanced in the liver of mice from the corn oil + ethanol group than in the palm oil + ethanol group. The corn oil + ethanol diet also inhibited the activation of both AMPK and downstream protein acetyl-CoA carboxylase (ACC) and promoted the SREBP-1c expression, subsequently accelerating lipid synthesis. In addition, 4-hydroxynonenal (4-HNE) levels in plasma and liver were significantly upregulated in response to corn oil + ethanol feeding. Interestingly, the in vitro study showed that 4-HNE significantly attenuated cell viability, elevated the expression of cleaved-caspase 3 protein and TG level, and regulated key molecules in ASK1-JNK and AMPK pathways in a dose-dependent manner. In conclusion, the n-6 PUFA diet showed a negative effect on alcohol-induced liver injury and steatosis. It might be related to the upregulation of 4-HNE and subsequent changes of proteins, namely, ASK1, JNK, AMPK, ACC, and SREBP-1c.

Breeding of ‘DND358’: A new soybean cultivar for processing soy protein isolate with a hypocholesterolemic effect similar to that of fenofibrate

• ‘DND358’ is ideal raw soy material for producing hypocholesterolemic SPI powder. • Modify protein subunit compositions is useful strategy for hypocholesterolemic soy breeding. • DND358-SPI: a superior diet-therapy soy beverage to achieve cholesterol homeostasis. • Enrich α′ subunit of 7S can be strategized in hypocholesterolemic soybean breeding. Soy proteins have hypocholesterolemic effects (HCE). Here, we developed a soybean cultivar ‘DND358’, which is superior for processing hypocholesterolemic soy protein isolate beverage powder (DND358-SPI). ‘DND358’ carries four recessive null alleles for the α subunit of 7S globulin and the G1, G2, and G4 subunits of 11S globulin (tetra null), was selected from a population derived from a three-way cross. The tetra null mutation resulted in a compensatory increase in the α′ subunit level and arginine content. The oral administration (300 mg/kg/day) of DND358-SPI processed from ‘DND358’ significantly decreased the fatty liver symptoms and hepatic lipid accumulation; reduced the hepatic total cholesterol (TC), triacylglycerol (TG) levels and atherogenic index (AI) value, in rats fed a high-cholesterol diet. Conversely, DND358-SPI administration markedly elevated high-density lipoprotein cholesterol levels, to values significantly higher to those fed on fenofibrate (FF, 30 mg/kg/day), a hypocholesterolemic drug. The HCE of DND358-SPI were similar to that of FF.

Dietary Supplementation with Sodium Butyrate Reduces High-sucrose Diet-induced Hepatic Accumulation of Triacylglycerols and Expression of Fatty Acid Synthesis Enzymes in Rats.

We investigated the effects of dietary supplementation with sodium butyrate (NaB) on the lipid levels, gene expression, and proteins related to lipid metabolism in nonalcoholic fatty liver disease (NAFLD) rat models fed a high-sucrose diet for 3 weeks. Supplementation with 1% and 3% NaB reduced high-sucrose-induced hepatic triacylglycerol levels and expression of genes and proteins related to fatty acid synthesis, such as fatty acid synthase and malic enzyme, in a dose-dependent manner. NaB supplementation did not affect hepatic cholesterol levels or expression of genes related to β-oxidation. NaB may prevent high-sucrose-induced NAFLD by repressing the fatty acid synthesis pathway.

Amycenone reduces excess body weight and attenuates hyperlipidaemia by inhibiting lipogenesis and promoting lipolysis and fatty acid β-oxidation in KK-Ay obese diabetic mice.

Excess body weight and hyperlipidaemia cause severe health problems and have social implications. Amycenone is an active substance extracted from Yamabushitake mushrooms with no reports of its activity against excess body weight and hyperlipidaemia. This research clarifies the effects and mechanisms of action of amycenone on the inhibition of body weight excess and hyperlipidaemia attenuation using KK-Ay mice. Amycenone or water was administered to 8-week-old male KK-Ay mice by gavage for 8 weeks. Their body weight and food intake were recorded during the experiment. At the end of the experimental period, the mice were dissected, and blood samples, lipid metabolism-related organs and tissues were collected and stored for further analysis. Amycenone treatment suppressed body weight gain and improved serum levels of fasting blood glucose and non-esterified fatty acids. Additionally, serum and hepatic cholesterol and triacylglycerol levels were reduced after this treatment, whereas the phosphorylation levels of AMPK, PKA and HSL increased and the expression level of FAS decreased. The protein level of C/EBPβ and gene expression level of Cpt1 were higher in the perirenal adipose tissue of amycenone-treated KK-Ay mice. Furthermore, amycenone phosphorylated AMPK, PKA and ACC, and PPARγ expression was lower in the mesenteric adipose tissue. The phosphorylation levels of AMPK, LKB1, PKA and ACC were also induced, and FAS expression level was reduced in the liver of the amycenone-treated group. Amycenone could reduce excess body weight and attenuate hyperlipidaemia in KK-Ay mice by inhibiting lipogenesis and promoting lipolysis through lipid metabolism pathway stimulation and fatty acid β-oxidation acceleration.

Dietary egg white protein hydrolysate improves orotic acid-induced fatty liver in rats by promoting hepatic phospholipid synthesis and microsomal triglyceride transfer protein expression

We investigated the effects of egg white protein hydrolysates (EWH) on orotic acid (OA)-induced nonalcoholic fatty liver (NAFL) in rats. Effects of the egg white protein (EWP) and EWH were also compared. Four groups of male Sprague-Dawley rats were separately fed AIN-76-based diets, supplemented with 20% casein for control, or with 1% OA, together with either 20% casein (OA), 20% EWP, or 20% EWH, respectively, for 3 d (developing stage) and 14 d (developed stage). In both feeding periods, animals from the OA group showed higher accumulation hepatic triacylglycerol (TAG) compared with those from the control group. In the 14-d experiment, dietary EWP and EWH significantly reduced the hepatic TAG levels. Intake of EWP reduced liver fat in OA-fed rats by 61%, while EWH reduced it by 92%. In addition, EWH restored the OA-induced high serum-TAG level to that seen in the control group. The 3 d experiment showed that consumption of EWH improved the expression of hepatic MTP, that was reduced by OA, without changing Mttp gene expression. It also increased the hepatic synthesis of PC and PE by enhancing the transcription of Pcyt1 and Pemt genes. Inclusion of EWP and EWH in the diet improves the OA-induced NAFL. EWH reduces the liver TAG better than EWP, and works more rapidly. Dietary EWH ameliorates OA-induced NAFL by promoting the secretion of hepatic TAG.

Albumin Knockout Mice Exhibit Reduced Plasma Free Fatty Acids but No Impairment in Whole Body Fat Oxidation

Abstract Objectives To improve understanding of the control of lipid metabolism, we aimed to determine whether lack of serum albumin decreases plasma free fatty acids (FFA), hepatic triacylglycerol (TAG), and whole body substrate oxidation in albumin knockout mice compared to wild type mice. Methods Male and female homozygous albumin knockout mice and C57BL/6J wild type controls, each on the 5k52 diet which contains a moderate fat content, were studied at 6–8 weeks of age. Body composition was tested by magnetic resonance. Substrate oxidation was measured by indirect calorimetry over 24 hours in metabolic cages. Plasma and tissues were collected after a 5-hour fast. Plasma FFA was measured by liquid chromatography/mass spectrometry (LC/MS). Hepatic TAG was measured by a colorimetric kit. Results In albumin knockout mice compared to the wild type mice, plasma FFA (P &amp;lt; 0.0001) and hepatic TAG content (P &amp;lt; 0.0001) were each reduced, while body fat percentage was increased (P &amp;lt; 0.01). In addition, female versus male showed higher hepatic TAG levels (P &amp;lt; 0.01). These results indicate that the lack of serum albumin decreases plasma FFA and hepatic TAG accumulation. However, the average 24-hour oxygen consumption, metabolic rate, and respiratory quotient (RQ) were not altered in albumin knockout mice, indicating that total fuel oxidation and relative contribution of lipid to whole body metabolism was not significantly unaltered. Conclusions We propose that lack of albumin reduces plasma FFA which diminishes hepatic TAG content through changes in the lipid supply to the liver. The results indicate that tissue lipid accumulation can be altered by targeting albumin without substantially disrupting whole body substrate oxidation, suggesting that metabolic control of FFA trafficking toward sites of ectopic lipid deposition and toward oxidation can be regulated independently of one another. Funding Sources McKinley Educational Initiative and the Purdue University College of Health and Human Sciences

Chronic Oleoylethanolamide Treatment Decreases Hepatic Triacylglycerol Level in Rat Liver by a PPARγ/SREBP-Mediated Suppression of Fatty Acid and Triacylglycerol Synthesis.

Oleoylethanolamide (OEA) is a naturally occurring bioactive lipid belonging to the family of N-acylethanolamides. A variety of beneficial effects have been attributed to OEA, although the greater interest is due to its potential role in the treatment of obesity, fatty liver, and eating-related disorders. To better clarify the mechanism of the antiadipogenic effect of OEA in the liver, using a lipidomic study performed by 1H-NMR, LC-MS/MS and thin-layer chromatography analyses we evaluated the whole lipid composition of rat liver, following a two-week daily treatment of OEA (10 mg kg−1 i.p.). We found that OEA induced a significant reduction in hepatic triacylglycerol (TAG) content and significant changes in sphingolipid composition and ceramidase activity. We associated the antiadipogenic effect of OEA to decreased activity and expression of key enzymes involved in fatty acid and TAG syntheses, such as acetyl-CoA carboxylase, fatty acid synthase, diacylglycerol acyltransferase, and stearoyl-CoA desaturase 1. Moreover, we found that both SREBP-1 and PPARγ protein expression were significantly reduced in the liver of OEA-treated rats. Our findings add significant and important insights into the molecular mechanism of OEA on hepatic adipogenesis, and suggest a possible link between the OEA-induced changes in sphingolipid metabolism and suppression of hepatic TAG level.

Tumor Necrosis Factor Alpha Knockout Promotes Adipose Fatty Acid Oxidation and Attenuates Insulin Resistance and Hepatic Steatosis in High Fat Diet-Fed Mice

Abstract Objectives Substantial evidence indicates that adipose tissue (AT) dysfunction and lipid spillover in obesity promote insulin resistance and non-alcoholic fatty liver disease. Tumor necrosis factor alpha (TNFα) is one of the pro-inflammatory cytokines overexpressed in obesity and its knockout (KO) attenuates diet-induced adiposity, lipid deposition in the liver and insulin resistance. However, the potential roles played by TNFα in fatty acid metabolism in AT have been incompletely understood. The objective of this study was to investigate the role of TNFα in obesity-induced insulin resistance with the goal of providing a potential target for therapeutics. Methods Three groups of wild type (WT) or TNFα KO male mice on the same B6 genetic background were fed designated diets for 16 weeks; WT fed a low-fat diet (LFD-WT), WT fed a high-fat diet (HFD-WT), and TNFα KO fed a HFD (HFD-TNFα KO). Blood concentrations of glucose and insulin and hepatic triacylglycerol (TG) levels were measured. The expression of genes involved in fatty acid and TG synthesis and fatty acid oxidation (FAO) was measured in epididymal white AT (eWAT). Results Compared to the LFD-fed mice, HFD-WT group had a significantly higher levels of blood glucose and insulin, and hepatic TG (P &amp;lt; 0.05). TNFα KO mice significantly improved HFD-induced hyperglycemia, hyperinsulinemia and hepatic TG accumulation (P &amp;lt; 0.05). In eWAT, TNFα ablation did not affect the expression of de novo fatty-acid synthesis-related genes, but significantly increased the expression of TG synthesis-related genes (p &amp;lt; 0.05). Moreover, TNFα KO presented a significantly increased expression of the FAO-related gene, CPT1, with a concomitant increase in the expression of glucose transporter 4 (GLUT4) and oxidative phosphorylation-related genes (CS and mt-CO1) (P &amp;lt; 0.05). Further evidence of the inhibition of fatty acid metabolism by TNFα includes a significant suppression of CPT1 as well as TG synthesis-related genes (P &amp;lt; 0.05) in 3T3-L1 adipocytes treated with TNFα. Conclusions These data indicate that antagonizing TNFα may mitigate diet-induced insulin resistance and hepatic steatosis by promoting FAO in obese AT. Funding Sources N/A.

Hepatic steatosis induced in C57BL/6 mice by a non-\xdf oxidizable fatty acid analogue is associated with reduced plasma kynurenine metabolites and a modified hepatic NAD+/NADH ratio

BackgroundNon-alcoholic fatty liver disease is often associated with obesity, insulin resistance, dyslipidemia, and the metabolic syndrome in addition to mitochondrial dysfunction and nicotinamide adenine dinucleotide (NAD+) deficiency. The aim of this study was to investigate how inhibition of mitochondrial fatty acid oxidation using the compound tetradecylthiopropionic acid (TTP) would affect hepatic triacylglycerol level and plasma levels of kynurenine (Kyn) metabolites and nicotinamide.Methods12 C57BL/6 mice were fed a control diet, or an intervention diet supplemented with 0.9% (w/w) tetradecylthiopropionic acid for 14 days. Blood and liver samples were collected, enzyme activities and gene expression were analyzed in liver, in addition to fatty acid composition. Metabolites in the tryptophan/kynurenine pathway and total antioxidant status were measured in plasma.ResultsDietary treatment with tetradecylthiopropionic acid for 2 weeks induced fatty liver accompanied by decreased mitochondrial fatty acid oxidation. The liver content of the oxidized form of NAD+ was increased, as well as the ratio of NAD+/NADH, and these changes were associated by increased hepatic mRNA levels of NAD synthetase and nicotinamide mononucleotide adenyltransferase-3. The downstream metabolites of kynurenine were reduced in plasma whereas the plasma nicotinamide content was increased. Some effects on inflammation and oxidative stress was observed in the liver, while the plasma antioxidant capacity was increased. This was accompanied by a reduced plasma ratio of kynurenine/tryptophan. In addition, a significant decrease in the inflammation-related arachidonic fatty acid in liver was observed.ConclusionFatty liver induced by short-time treatment with tetradecylthiopropionic acid decreased the levels of kynurenine metabolites but increased the plasma levels of NAD+ and nicotinamide. These changes are most likely not associated with increased inflammation and oxidative stress. Most probably the increase of NAD+ and nicotinamide are generated through the Preiss Handler pathway and/or salvage pathway and not through the de novo pathway.The take home message is that non-alcoholic fatty liver disease is associated with the metabolic syndrome in addition to mitochondrial dysfunction and nicotinamide adenine dinucleotide (NAD+) deficiency. Inducing fatty liver in mice by inhibition of fatty acid oxidation resulted in a concomitant change in kynurenine metabolites increasing the plasma levels of nicotinamides and the hepatic NAD+/NADH ratio, probably without affecting the de novo pathway of kynurenines.

Anti-obesity effect of Melandrium firmum Rohrbach extract in 3T3-L1 cells and high-fat diet-induced obese C57BL/6N mice.

In this study, we first investigated the influence of Melandrium firmum Rohrbach (MF) on the accumulation of lipid content in 3T3‐L1 cells and in vitro results showed that MF extraction suppressed the differentiation of 3T3‐L1 pre‐adipocytes in a concentration‐dependent manner without showing cytotoxicity. Hence, we studied the effects of MF on preventing obesity in C57BL/6N mice. The results showed that MF decreased food efficiency ratio, body weight, epididymal adipose and hepatic tissue weight, hepatic lipid metabolites, and triacylglycerol and cholesterol serum levels, when compared with the high‐fat diet group. Moreover, MF significantly inhibited the expression of genes related to adipogenesis, such as PPAR‐γ, C/EBP‐α, and aP2, and those related to lipogenesis, such as SREBP‐1c, FAS, SCD‐1, and CD36 in epididymal adipose and liver tissues. These anti‐adipogenic and anti‐lipogenic effects of MF suggest that it could be used as a food including potential functional ingredient to prevent high‐fat diet‐induced obesity.

Anti-steatotic linagliptin pleiotropic effects encompasses suppression of de novo lipogenesis and ER stress in high-fat-fed mice

AimTo investigate the effects of linagliptin treatment on hepatic energy metabolism and ER stress in high-fat-fed C57BL/6 mice. MethodsForty male C57BL/6 mice, three months of age, received a control diet (C, 10% of lipids as energy, n = 20) or high-fat diet (HF, 50% of lipids as energy, n = 20) for 10 weeks. The groups were randomly subdivided into four groups to receive linagliptin, for five weeks, at a dose of 30 mg/kg/day added to the diets: C, C-L, HF, and HF-L groups. ResultsThe HF group showed higher body mass, total and hepatic cholesterol levels and total and hepatic triacylglycerol levels than the C group, all of which were significantly diminished by linagliptin in the HF-L group. The HF group had higher hepatic steatosis than the C group, whereas linagliptin markedly reduced the hepatic steatosis (less 52%, P < 0.001). The expression of Sirt1 and Pgc1a was more significant in the HF-L group than in the HF group. Linagliptin also elicited enhanced GLP-1 concentrations and a reduction in the expression of the lipogenic genes Fas and Srebp1c. Besides, HF-L showed a reduction in the genes related to endoplasmic reticulum stress Chop, Atf4, and Gadd45 coupled with reduced apoptotic nuclei immunostaining. ConclusionLinagliptin caused a marked reduction in hepatic steatosis as a secondary effect of its glucose-lowering property. NAFLD countering involved reduced lipogenesis, increased beta-oxidation, and relief in endoplasmic reticulum stress, leading to reduced apoptosis and better preservation of the hepatic structure. Therefore, linagliptin may be used, preferably in diabetic patients, to avoid the progression of hepatic steatosis.

Low utilization of glucose in the liver causes diet-induced hypercholesterolemia in exogenously hypercholesterolemic rats.

Exogenously hypercholesterolemic (ExHC) rats develop diet-induced hypercholesterolemia (DIHC) when fed with dietary cholesterol. Previously, we reported that, under the high-sucrose-diet-feeding condition, a loss-of-function mutation in Smek2 results in low activity of fatty acid synthase (FAS) followed by the shortage of hepatic triacylglycerol content in ExHC rats and the onset of DIHC. However, the relationship between the Smek2 mutation and FAS dysfunction is still unclear. Here, we focused on carbohydrate metabolism, which provides substrates for FAS, and analyzed carbohydrate and lipid metabolisms in ExHC rats to clarify how the deficit of Smek2 causes DIHC. Male ExHC and SD rats were fed high-sucrose or high-starch diets containing 1% cholesterol for 2 weeks. Serum cholesterol levels of the ExHC rats were higher, regardless of the dietary carbohydrate. Hepatic triacylglycerol levels were higher in only the SD rats fed the high-sucrose diet. Moreover, the ExHC rats exhibited a diabetes-like status and accumulation of hepatic glycogen and low hepatic mRNA levels of liver-type phosphofructokinase (Pfkl), which encodes a rate-limiting enzyme for glycolysis. These results suggest that the glucose utilization, particularly glycolysis, is impaired in the liver of ExHC rats. To evaluate how the diet with extremely low glucose affect to DIHC, ExHC.BN-Dihc2BN, a congenic strain that does not develop DIHC, and ExHC rats were fed a high-fructose diet containing 1% cholesterol for 2 weeks. The serum cholesterol and hepatic triacylglycerol levels were similar in the strains. Results of water-soluble metabolite analysis with primary hepatocytes, an increase in fructose-6-phosphate and decreases in succinate, malate and aspartate in ExHC rats, support impaired glycolysis in the ExHC rats. Thus, the Smek2 mutation causes abnormal hepatic glucose utilization via downregulation of Pfkl expression. This abnormal glucose metabolism disrupts hepatic fatty acid synthesis and causes DIHC in the ExHC rats.