A model of insulin resistance and nonalcoholic steatohepatitis in rats: role of peroxisome proliferator-activated receptor-alpha and n-3 polyunsaturated fatty acid treatment on liver injury

Different Regulatory Effects of Heated Products and Maillard Reaction Products of Half-Fin Anchovy Hydrolysates on Intestinal Antioxidant Defense in Healthy Animals

The oxidative state of intestinal tracts of healthy animals were investigated after short-term intake of half-fin anchovy hydrolysates (HAHp) and their thermal or Maillard reaction products (MRPs). After one month of continuous oral gavage of HAHp, HAHp-heated products (HAHp-H), the MRPs of HAHp with 3% of glucose (HAHp-3%G MRPs), and the MRPs of HAHp with 3% of fructose (HAHp-3%F MRPs) at a dose of 1.0 g/kg of body weight per day into healthy ICR male mice, the concentrations of serum low-density and high-density lipoprotein cholesterol did not significantly change compared to the control group (CK, gavage with saline). Similar results were found for the interleukin-6 concentrations of all groups. By comparison, HAHp-H, HAHp-3%G MRPs, and HAHp-3%F MRPs administration decreased serum tumor necrosis factor-α concentration as compared to the CK group (p < 0.05). No histological damage was observed in the jejunum, ileum, and colonic tissues of all groups. However, HAHp-H treatment induced higher upregulation of Kelch-like ECH-associated protein 1, transcription factors Nrf-2, associated protective phase-II enzymes of NAD(P)H: quinine oxidoreductase-1, and hemoxygenase-1 in colon tissue, as well as higher upregulation of endogenous antioxidant enzymes, including copper/zinc superoxide dismutase, manganese superoxide dismutase, catalase, and glutathione peroxidase 2 than other groups (p < 0.05). Additionally, increases in Nε-carboxymethyllysine expression in the colonic tissues of all groups were consistent with their increased oligopeptide transporter 1 expressions. Our results suggest that the thermal products of HAHp might have a broad application prospect in improving antioxidant defense in vivo in healthy animals.

Dietary fatty acids and risk of non-alcoholic steatohepatitis: A national study in the United States

Background

Non-alcoholic steatohepatitis (NASH), the early invertible stage of non-alcoholic fatty liver disease, has become a public health challenge due to the great burden and lack of effective treatment. Dietary nutrients are one of the modifiable factors to prevent and slow down disease progression. However, evidence linking dietary fatty acids intake and risk of NASH is lacking.

Objectives

This study aimed to examine the association between dietary total saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), their subtypes, the ratio of unsaturated (UFAs) to SFAs, and the risk of NASH among a nationwide population in the United States.

Methods

This cross-sectional study was conducted among 4,161 adults in the national health and nutrition examination survey in 2017-2018 cycle. Moreover, NASH was defined by transient elastography. Dietary fatty acids were assessed using a validated 24-h food recall method. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs).

Results

A total of 2,089 (50.2%) participants with NASH were identified. Compared with participants in the bottom tercile of dietary intakes of total PUFAs, those in the highest tercile had lower risk of NASH, with an adjusted OR of 0.67 (95% CI: 0.46-0.97). Similar associations were found between the subtype of PUFA 18:3 and NASH, while the fully adjusted OR in the highest tercile was 0.67 (95% CI: 0.47-0.96). Interactions of dietary PUFAs and body mass index (BMI) could be found influencing NASH risk. Stronger associations of dietary total PUFAs intakes with NASH risk were found in obese participants (OR, 95% CI: 0.41, 0.22-0.75) than in the non-obese participants (OR, 95% CI: 1.00, 0.70-1.43; p-interaction = 0.006). Similar effects on risk of NASH were also observed between BMI and dietary intakes of PUFA 18:3. However, no significant associations were observed between NASH risk and dietary total SFAs, MUFAs, their subtypes as well as the ratio of UFAs to SFAs.

Conclusion

Dietary intakes of total PUFAs, as well as its subtype of PUFA 18:3, were inversely associated with risk of NASH. The further large prospective studies need to be conducted to confirm the findings of this study.

Effect of Probiotics Therapy on Nonalcoholic Fatty Liver Disease

Objective

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease in the world. The pathogenesis of NAFLD is complex and multifactorial. Clinical studies have shown that alterations in the gut microbiota play a key role in NAFLD. The purpose of this study was to analyze the effect of probiotic supplementation on the treatment of NAFLD patients based on various indicators.

Methods

We conducted a meta-analysis investigating the relationship between NAFLD and probiotic supplementation. Embase, PubMed, and Web of Science databases were searched by computer, and then, eligible studies were identified. Finally, a total of high-quality randomized controlled trials were selected involving 1403 participants. Meta-analysis was performed using the RevMan 5.3 software which was systematically searched for works published through Dec. 1, 2021, in the present study.

Results

The meta-analysis results showed that the probiotics supplementation improved hepatocyte injury and significantly reduced the level of ALT (P = 0.00001), AST (P = 0.0009), GGT (P = 0.04), TG (P = 0.01), LDL-C (P = 0.0005), HDL-C (P = 0.0002), insulin (P = 0.003), IR (P = 0.03), BMI (P = 0.03), TNF-α (P = 0.03), and CRP (P = 0.02), respectively, in NAFLD patients.

Conclusion

The present study suggests that probiotics therapy may improve liver enzyme levels, regulated lipid metabolism, reduced insulin resistance, and improved inflammation in NAFLD patients. It supports the potential role of probiotics supplementation in the treatment of NAFLD.

In Vitro Hepatoprotective and Human Gut Microbiota Modulation of Polysaccharide-Peptides in Pleurotus citrinopileatus

Pleurotus citrinopileatus, a golden oyster mushroom, is popular in Asia and has pharmacological functions. However, the effects of polysaccharide-peptides extracted from Pleurotus citrinopileatus and underlying mechanism on digestive systme have not yet been clarified. Here, we determined the composition of two polysaccharide-peptides (PSI and PSII) from P. citrinopileatus and investigated the protective effects of on hepatoprotective and gut microbiota. The results showed that PSI and PSII were made up of similar monosaccharide moieties, except for the varying ratios. Furthermore, PSI and PSII showed that they have the hepatoprotective effects and significantly increased the viabilities and cellular total superoxide dismutase activities increased significantly in HepG2 cells. Intracellular triglyceride content and extracellular alanine aminotransferase and aspartate transaminase contents markedly decreased following treatment with 40 and 50 μg/mL PSI and PSII, respectively. Moreover, PSI and PSII activated the adiponectin pathway and reduced lipid accumulation in liver cells. PSI and PSII elevated short-chain fatty acid concentrations, especially butyric and acetic acids. 16S rRNA gene sequencing analysis showed that PSI promoted the relative abundances of Bifidobacteria, Lactobacillus, Faecalibacterium, as well as Prevotella generas in the gut. PSII markedly suppressed the relative abundances of Escherichia-Shigella and Bacteroides generas. We speculate that the PSI and PSII play a role through liver-gut axis system. Polysaccharide-peptides metabolize by gut microbiota to produce short-chain fatty acids (SCFAs) and in turn influence liver functions.

Lipotoxicity as the Leading Cause of Non-Alcoholic Steatohepatitis

The emerging issues nowadays are non-alcoholic fatty liver disease (NAFLD) and its advanced stage non-alcoholic steatohepatitis (NASH), which further can be a predisposing factor for chronic liver complications, such as cirrhosis and/or development of hepatocellular carcinoma (HCC). Liver lipotoxicity can influence the accumulation of reactive oxygen species (ROS), so oxidative stress is also crucial for the progression of NASH. Moreover, NASH is in strong connection with metabolic disorders, and supporting evidence shows that insulin resistance (IR) is in a close relation to NAFLD, as it is involved in the progression to NASH and further progression to hepatic fibrosis. The major issue is that, at the moment, NASH treatment is based on lifestyle changes only due to the fact that no approved therapeutic options are available. The development of new therapeutic strategies should be conducted towards the potential NAFLD and NASH treatment by the modulation of IR but also by dietary antioxidants. As it seems, NASH is going to be the leading indication for liver transplantation as a consequence of increased disease prevalence and the lack of approved treatment; thus, an effective solution is needed as soon as possible.

Brown Rice Inhibits Development of Nonalcoholic Fatty Liver Disease in Obese Zucker (fa/fa) Rats by Increasing Lipid Oxidation Via Activation of Retinoic Acid Synthesis

BACKGROUND

White rice and its unrefined form, brown rice, contain numerous compounds that are beneficial to human health. However, the starch content of rice can contribute to obesity, a main risk factor for nonalcoholic fatty liver disease (NAFLD).

OBJECTIVES

We investigated the effect of rice consumption on NAFLD and its underlying molecular mechanism.

METHODS

We randomly divided 7-week-old male obese Zucker (fa/fa) rats, an animal model of NAFLD, into 3 groups (n = 10 each) fed 1 of 3 diets for 10 weeks: a control diet (Cont; AIN-93G diet; 53% cornstarch), a white rice diet (WR; AIN-93G diet with cornstarch replaced with white rice powder), or a brown rice diet (BR; AIN-93G diet with cornstarch replaced with brown rice powder). Liver fat accumulation and gene expression related to lipid and vitamin A metabolisms, including retinoic acid (RA) signaling, were analyzed.

RESULTS

Hepatic lipid values were significantly decreased in the BR group compared with the Cont group, by 0.4-fold (P < 0.05). The expression of genes related to hepatic fatty acid oxidation, such as carnitine palmitoyltransferase 2, was approximately 2.1-fold higher in the BR group than the Cont group (P < 0.05). The expression of peroxisomal acyl-coenzyme A oxidase 1 and acyl-CoA dehydrogenase medium chain was also significantly increased, by 1.6-fold, in the BR group compared with the Cont group (P < 0.05). The expression of VLDL-secretion-related genes, such as microsomal triglyceride transfer protein, was also significantly higher in the BR group (2.4-fold; P < 0.05). Furthermore, aldehyde dehydrogenase 1 family member A1, an RA synthase gene, was 2-fold higher in the BR group than the Cont group (P < 0.05).

CONCLUSIONS

Brown rice prevented development of NAFLD in obese Zucker (fa/fa) rats. The beneficial effects of pregelatinized rice on NAFLD could be manifested as increased fatty acid oxidation and VLDL secretion, which are regulated by RA signaling.

ω3PUFAs improve hepatic steatosis in postnatal overfed rats and HepG2 cells by inhibiting acetyl-CoA carboxylase

Postnatal overfeeding can lead to persistent increases in hepatic lipid synthesis and the risk of nonalcoholic fatty liver disease (NAFLD) in adulthood. The ω3 polyunsaturated fatty acids (ω3PUFAs) exhibit beneficial effects on NAFLD. Here, we employed a rat model and an in vitro HepG2 cell model to investigate whether fish oil (FO) affects hepatic lipid synthesis due to postnatal overfeeding. Male Sprague-Dawley were divided into litter sizes of three (small litters, SLs) or 10 (normal litters, NLs) on postnatal day 3 and were fed standard chow or FO diet beginning on postnatal week 3 to generate NL, SL, NL-FO, and SL-FO groups. The results indicated that the FO diet reduced the postnatal overfeeding-induced body weight gain and NAFLD characteristics (such as serum and liver triglyceride (TG) and hepatic steatosis). In addition, FO restored the expression of hepatic lipid metabolism-related genes (including SCD1, FASN, CPT1, LPL, ACC, and SREBP-1c) in SL-FO rats. Specifically, the activity and expression pattern of ACC were consistent with SREBP-1c. Furthermore, HepG2 cells were treated with oleic acid (OA), followed by eicosapentenoic acid (EPA), with or without SREBP-1c siRNA. The cellular lipid droplets, TG content, and the expression of ACC (by 75%) and SREBP-1c (by 45%) were increased by OA stimulation (p < .05), which was inhibited by EPA treatment. However, the effect of EPA treatment was abolished when SREBP-1c was silenced. In conclusion, ω3PUFAs-rich diet may be an effective way to reverse the developmental programming of hepatic lipid synthesis, at least partially, by inhibiting ACC through modulating SREBP-1c.

Altered Microbiota Diversity and Bile Acid Signaling in Cirrhotic and Noncirrhotic NASH-HCC

The precipitous increase in nonalcoholic steatohepatitis (NASH) is accompanied by a dramatic increase in the incidence of NASH-related hepatocellular carcinoma (HCC). HCC in NASH has a higher propensity to arise without pre-existing cirrhosis compared with other chronic liver diseases.

Hepatoprotective effect of selected isoandrographolide derivatives on steatotic HepG2 cells and High Fat Diet fed rats

Non-alcoholic Fatty Liver Disease (NAFLD) is one of the growing epidemics of the globe. This study was aimed to evaluate the anti-NAFLD effect of selected IAN derivatives using in silico, in vitro and in vivo models. In silico tools viz., DataWarrior, SwissADME and Gaussian 09 were used to predict the pharmacokinetic properties and electronic distribution patterns of the derivatives; docking analysis was done with Autodock against PPARα. Toxicities of the derivatives were assessed in HepG2 cells using MTT assay. Anti-NAFLD efficacies of the derivatives were assessed in free fatty acid induced steatotic HepG2 cells. In vivo anti-NAFLD effect of active isoandrographolide (IAN) derivative, 19-propionyl isoandrographolide (IAN-19P) was assessed in High Fat Diet fed rats. In silico and in vitro studies indicated that IAN-19P showed improved drug-likeness and drug score. The toxicity of IAN-19P to HepG2 cells was comparatively less than IAN and other derivatives. In free fatty acid induced steatotic HepG2 cells, treatment with IAN-19P significantly lowered intracellular triglyceride content and leakage of LDH and transaminases. Treating High Fat Diet fed animals with IAN-19P significantly lowered plasma lipids, transaminases, LDH and GGT levels. The treatment with IAN-19P upregulated the expressions of PPARα and CPT-1. IAN-19P did not produce any noticeable adverse effect till 2 g/kg concentration in acute and 250 mg/kg concentration in subacute toxicity studies. This study indicated the beneficial effect of IAN-19P for the treatment of NAFLD; however robust investigations are needed to establish the potential of IAN-19P to treat NAFLD.

Glycerol Monocaprylate Modulates Gut Microbiota and Increases Short-Chain Fatty Acids Production without Adverse Effects on Metabolism and Inflammation

Glycerol monocaprylate (GMC) is a glycerol derivative of medium-chain fatty acids (MCFAs) and is widely used as a preservative in food processing. However, GMC and its hydrolytic acid (octylic acid) have antibacterial properties that may affect the physiology and intestinal microecology of the human body. Therefore, in this study, the effects of two different dosages of GMC (150 and 1600 mg kg-1) on glucose, lipid metabolism, inflammation, and intestinal microecology of normal diet-fed C57BL/6 mice were comprehensively investigated. The obtained results showed that the level of triglycerides (TGs) in the low-dose group down-regulated significantly, and the anti-inflammatory cytokine interleukin 10 (IL-10) significantly increased, while the pro-inflammatory cytokines monocyte chemotactic protein 1 (MCP-1) and interleukin 1beta (IL-1β) in the high-dose group were significantly decreased. Importantly, GMC promoted the α-diversity of gut microbiota in normal-diet-fed mice, regardless of dosages. Additionally, it was found that the low-dose treatment of GMC significantly increased the abundance of Lactobacillus, while the high-dose treatment of GMC significantly increased the abundance of SCFA-producers such as Clostridiales, Lachnospiraceae, and Ruminococcus. Moreover, the content of short-chain fatty acids (SCFAs) was significantly increased by GMC supplementation. Thus, our research provides a novel insight into the effects of GMC on gut microbiota and physiological characteristics.

Modeling Diet-Induced NAFLD and NASH in Rats: A Comprehensive Review

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, characterized by hepatic steatosis without any alcohol abuse. As the prevalence of NAFLD is rapidly increasing worldwide, important research activity is being dedicated to deciphering the underlying molecular mechanisms in order to define new therapeutic targets. To investigate these pathways and validate preclinical study, reliable, simple and reproducible tools are needed. For that purpose, animal models, more precisely, diet-induced NAFLD and nonalcoholic steatohepatitis (NASH) models, were developed to mimic the human disease. In this review, we focus on rat models, especially in the current investigation of the establishment of the dietary model of NAFLD and NASH in this species, compiling the different dietary compositions and their impact on histological outcomes and metabolic injuries, as well as external factors influencing the course of liver pathogenesis.

Fatty Acid Desaturase 1 Influences Hepatic Lipid Homeostasis by Modulating the PPARα-FGF21 Axis

The fatty acid desaturase 1 (FADS1), also known as delta-5 desaturase (D5D), is one of the rate-limiting enzymes involved in the desaturation and elongation cascade of polyunsaturated fatty acids (PUFAs) to generate long-chain PUFAs (LC-PUFAs). Reduced function of D5D and decreased hepatic FADS1 expression, as well as low levels of LC-PUFAs, were associated with nonalcoholic fatty liver disease. However, the causal role of D5D in hepatic lipid homeostasis remains unclear. In this study, we hypothesized that down-regulation of FADS1 increases susceptibility to hepatic lipid accumulation. We used in vitro and in vivo models to test this hypothesis and to delineate the molecular mechanisms mediating the effect of reduced FADS1 function. Our study demonstrated that FADS1 knockdown significantly reduced cellular levels of LC-PUFAs and increased lipid accumulation and lipid droplet formation in HepG2 cells. The lipid accumulation was associated with significant alterations in multiple pathways involved in lipid homeostasis, especially fatty acid oxidation. These effects were demonstrated to be mediated by the reduced function of the peroxisome proliferator-activated receptor alpha (PPARα)-fibroblast growth factor 21 (FGF21) axis, which can be reversed by treatment with docosahexaenoic acid, PPARα agonist, or FGF21. In vivo, FADS1-knockout mice fed with high-fat diet developed increased hepatic steatosis as compared with their wild-type littermates. Molecular analyses of the mouse liver tissue largely corroborated the observations in vitro, especially along with reduced protein expression of PPARα and FGF21. Conclusion: Collectively, these results suggest that dysregulation in FADS1 alters liver lipid homeostasis in the liver by down-regulating the PPARα-FGF21 signaling axis.

Bile salt hydrolase-overexpressing Lactobacillus strains can improve hepatic lipid accumulation in vitro in an NAFLD cell model

Background

Non-alcoholic fatty liver disease (NAFLD) includes a range of liver diseases that occur in the absence of significant alcohol consumption. The probiotic bacterial strains Lactobacillus casei LC2W, which overexpresses the bile salt hydrolase (BSH) gene (referred to as pWQH01), and Lactobacillus plantarum AR113, which exhibits high BSH activity, have been shown to improve hepatic lipid accumulation and may lower cholesterol levels in vivo. These effects may be BSH-dependent, as L. casei LC2W without BSH activity did not exert these beneficial effects.

Objective

This study aimed to investigate the effects of Lactobacillus with high BSH activity on cholesterol accumulation and lipid metabolism abnormalities in oleic acid (OA)- and cholesterol-induced HepG2 cell models, and to determine the mechanism underlying the effects.

Design

A HepG2 cell model of OA-induced steatosis and cholesterol-induced cholesterol accumulation was developed. OA- and cholesterol-treated HepG2 cells were incubated with L. plantarum AR113, L. casei LC2W or L. casei pWQH01 for 6 h at 37°C with 5% CO₂. Subsequently, a series of indicators and gene expressions were analysed.

Results

Both L. plantarum AR113 and L. casei pWQH01 significantly reduced lipid accumulation, total cholesterol (TC) levels and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) mRNA expression relative to the control group, whereas L. casei LC2W had no similar effect. Additionally, exposure to L. plantarum AR113 or L. casei pWQH01 significantly reduced the expression of sterol regulatory element-binding protein 1c (SREBP-1c), Acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS) and tumour necrosis factor-α (TNF-α) andsignificantly increased the expression of 5' adenosine monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor alpha (PPARα).

Conclusion

Both L. plantarum AR113 and L. casei pWQH01 appear to improve steatosis in vitro in a BSH-dependent manner.

Aqueous extract from Pepino (Solanum muricatum Ait.) leaves ameliorated insulin resistance, hyperlipidemia, and hyperglycemia in mice with metabolic syndrome

Solanum muricatum Ait. (Pepino) is a plant food commonly cultivated in the Penghu Island, Taiwan. This present study aimed to investigate the protective effects of aqueous extract of Pepino leaves (AEPL) in mice with metabolic syndrome. Metabolic syndrome animal model was induced by continuous high-fat diet feeding and low-dose streptozotocin (40 mg/ml) for 5 days. A 1% AEPL or metformin were given for 6 weeks after streptozotocin injection. The results revealed that 1% AEPL effectively reduced fasting blood glucose, insulin resistance, and hyperlipidemia in metabolic syndrome mice. Histologic examination revealed lipid accumulation in liver decreased by 1% AEPL treatment. Further, western blot analysis revealed 1% AEPL treatment managed enzymes related to lipid synthesis and oxidation pathways and hepatic glucose production. Besides, 1% AEPL treatment increased liver antioxidant activities to against oxidative stress. These results concluded that AEPL treatment attenuated insulin resistance, hyperlipidemia, and hyperglycemia of metabolic syndrome. PRACTICAL APPLICATIONS: Metabolic syndrome (MS) is a multifactorial chronic disease which is characterized by dyslipidemia, insulin resistance, and hyperglycemia. However, there is no single drug or defined medication for MS so far. The present study revealed that AEPL treatment was able to regulate lipid metabolism and glycemic control at the molecular level to alleviate MS. AEPL has the potential to be a novo complementary medication for metabolic syndrome.

Targeting n-3 Polyunsaturated Fatty Acids in Non-Alcoholic Fatty Liver Disease

BACKGROUND

Non-Alcoholic Fatty Liver Disease (NAFLD) is characterized by abnormal hepatic accumulation of triacylglycerides in the absence of alcohol consumption, in association with Oxidative Stress (OS), a pro-inflammatory state and Insulin Resistance (IR), which are attenuated by n-3 long-chain polyunsaturated Fatty Acids (FAs) C20-C22 (LCPUFAs) supplementation. Main causes of NAFLD comprise high caloric intake and a sedentary lifestyle, with high intakes of saturated FAs.

METHODS

The review includes several searches considering the effects of n-3 LCPUFAs in NAFLD in vivo and in vitro models, using the PubMed database from the National Library of Medicine- National Institutes of Health.

RESULT

The LCPUFAs eicosapentaenoic acid (C20:5 n-3, EPA) and docosahexaenoic acid (C22:6 n- 3, DHA) have a positive effect in diminishing liver steatosis, OS, and the levels of aspartate aminotransferase, alanine aminotransferase and pro-inflammatory cytokines, with improvement of insulin sensitivity and adiponectin levels. The molecular pathways described for n-3 LCPUFAs in cellular and animal models and humans include peroxisome proliferator-activated receptor-α activation favouring FA oxidation, diminution of lipogenesis due to sterol responsive element binding protein-1c downregulation and inflammation resolution. Besides, nuclear factor erythroid-2-related factor-2 activation is elicited by n-3 LCPUFA-derived oxidation products producing direct and indirect antioxidant responses, with concomitant anti-fibrogenic action.

CONCLUSION

The discussed effects of n-3 LCPUFA supplementation support its use in NAFLD, although having a limited value in NASH, a contention that may involve n-3 LCPUFA oxygenated derivatives. Clinical trials establishing optimal dosages, intervention times, type of patients and possible synergies with other natural products are needed in future studies.

Evaluation of Insulin Resistance Induced Brain Tissue Dysfunction in Obese Dams and their Neonates: Role of Ipriflavone Amelioration

BACKGROUND

Nonalcoholic steatohepatitis (NASH) is associated with activation of liver fibrogenesis and predisposes to cirrhosis and associated morbi-mortality. A high fat high cholesterol diet (HFD) was provided to female albino rats to establish a NASH model. It is well known that the offspring of obese mothers have an increased risk of obesity and diabetes. The present study aimed at evaluating the ameliorative effects of ipriflavone (IP) as a natural food supplement on lipid metabolism, improving insulin sensitivity, reducing oxidative stress and inflammation, modifying metabolic risk factors and/or reduce brain damage, in both neonates and their dams.

MATERIALS AND METHODS

The present aim was achieved by evaluating the oxidative stress and antioxidant defense system biomarkers, as thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH), catalase, and superoxide dismutase (SOD) activities. In addition, the neurotransmitter acetylcholine (Ach) and acetylcholine esterase (AchE) activities, as well as levels of the apolipoprotein E4 (APOE4); β-secretase, hyper phosphor-tau and β-amyloid 42; 3-hydroxy- 3-methyl glutaryl coenzyme A reductase (HMG CoA R)" and COX-II by immunoblotting assays in the brain tissue of neonates and their dams in all the studied groups.

RESULTS

A very significant amelioration in acetylcholine and acetylcholine esterase neurotransmitters, Alzheimer's makers (β-amyloid), antioxidants (reduced glutathione (GSH) contents, catalase (CAT) and superoxide dismutase (SOD); and inflammatory cytokines in NASH model is observed upon administrating ipriflavone (IP) as a natural food supplement. The multifunctional activities of ipriflavone as an antioxidant, anti-inflammatory and anti-insulin resistance drug were discussed and correlated with other investigations.

CONCLUSION

Regarding steatohepatitis, the present study confirmed the anti-inflammatory effects of the ipriflavone (IP). Therefore, future studies should focus on hepatic fatty acid uptake, hepatic lipogenesis, and fatty acid oxidation and the role of IP in regulating hepatic fat metabolism. In addition, natural products like IP could be combined with the highly used pharmaceutical drugs to reduce the side effects of nonalcoholic steatohepatitis, and minimize progression of dementia. Moreover, the present study supports further attempts to heal the neural dysfunction via antioxidant and anti-inflammatory cascade activities using ipriflavone (IP).

Animal Models of Fibrosis in Nonalcoholic Steatohepatitis: Do They Reflect Human Disease?

Nonalcoholic steatohepatitis (NASH) is one of the most common chronic liver diseases in the world, yet no pharmacotherapies are available. The lack of translational animal models is a major barrier impeding elucidation of disease mechanisms and drug development. Multiple preclinical models of NASH have been proposed and can broadly be characterized as diet-induced, deficiency-induced, toxin-induced, genetically induced, or a combination of these. However, very few models develop advanced fibrosis while still reflecting human disease etiology or pathology, which is problematic since fibrosis stage is considered the best prognostic marker in patients and an important endpoint in clinical trials of NASH. While mice and rats predominate the NASH research, several other species have emerged as promising models. This review critically evaluates animal models of NASH, focusing on their ability to develop advanced fibrosis while maintaining their relevance to the human condition.

[Establishment of high-fat diet-induced obesity and insulin resistance model in rats]

OBJECTIVE

To investigate the appropriate conditions and duration for establishing a high-fat diet-induced obesity and insulin resistance model in rats.

METHODS

Forty-five 6-week-old male Sprague-Dawley (SD) rats were randomly assigned into 2 groups: (1) control group (CON), (2) high-fat diet group (HFD). HFD was fed with a high-fat diet (45% kcal from fat) while CON with chow diet. After four-weeks of high-fat diet feeding, the rats of obesity resistance (OR) were eliminated according to body weight sorting, whereas obese (OB) rats were continued feeding a high-fat diet until 12 weeks. Body weight and food intake were recorded weekly. Glucose tolerance was evaluated by oral glucose tolerance test (OGTT) in 4 weeks, 8 weeks and 12 weeks. At the end of 12 weeks, insulin releasing test and visceral fat mass were measured and HE staining of the liver, adipose tissue and pancreatic tissue were conducted.

RESULTS

After 4 weeks of a high-fat diet, the body weight of HFD was 17.8% higher than that of CON (P=0.001), and the rate of obesity was 67.6%-78.4%. Glucose tolerance of OB rats was impaired with a higher blood glucose concentration at 120 min (P<0.001) and a higher area under the curve (AUC, P=0.037) in OGTT compared with CON. The rate of obesity and insulin-resistance rats was 79.3%. After 8 weeks of feeding, the body weight in OB was 30.4% higher than CON (P<0.001). In OGTT, blood glucose levels at 60 min and 120 min were 35.6% and 36.4% higher than those in CON (both P<0.001), and AUC was 21.7% (P<0.001) higher than that of CON. The rate of obesity and insulin-resistance rats was 100.0%. After 12 weeks of feeding, the body weight in OB was 36.9% higher than that in CON (P<0.001). In OGTT, the blood glucose levels at 60 min and 120 min were 24.8% (P=0.001) and 34.6% (P<0.001) higher than those in CON, and AUC was 16.1% (P=0.019) higher than that of CON. The rate of obesity and insulin-resistance rats was 93.3%. The insulin releasing test showed that serum insulin concentration at each time point (0, 30, 60, 120 min) was higher than that in CON, with a 6.3-times higher than that in CON at 120 min (P=0.008). Pathological changes were observed in islets and liver in the OB rats.

CONCLUSION

After 4 weeks of a high-fat diet (45% kcal from fat) feeding in six-weeks SD rats, the rats of OR were eliminated. Impaired glucose tolerance was found in OB rats after 4 weeks of feeding, and the rate was higher after 8-12 weeks of high-fat diet feeding.

Targeted Nutrient Modifications in Purified Diets Differentially Affect Nonalcoholic Fatty Liver Disease and Metabolic Disease Development in Rodent Models

Nonalcoholic fatty liver disease (NAFLD) is a complex spectrum of disorders ranging from simple benign steatosis to more aggressive forms of nonalcoholic steatohepatitis (NASH) and fibrosis. Although not every patient with NAFLD/NASH develops liver complications, if left untreated it may eventually lead to cirrhosis and hepatocellular carcinoma. Purified diets formulated with specific nutritional components can drive the entire spectrum of NAFLD in rodent models. Although they may not perfectly replicate the clinical and histological features of human NAFLD, they provide a model to gain further understanding of disease progression in humans. Owing to the growing demand of diets for NAFLD research, and for our further understanding of how manipulation of dietary components can alter disease development, we outlined several commonly used dietary approaches for rodent models, including mice, rats, and hamsters, time frames required for disease development and whether other metabolic diseases commonly associated with NAFLD in humans occur.

THE EFFECT OF N-STEAROYLETHANOLAMINE ON THE ADIPOCYTE FATTY ACID COMPOSITION OF DIFFERENT AGE RATS WITH OBESITY-INDUCED INSULIN RESISTANCE

Chronic hypernutrition and high fat diet (HFD), rich in saturated fatty acids leads to molecular changes in insulin sensitive tissues and is followed by dyslipidemia. That is why the aim of our study was to investigate the fatty acid (FA) composition of phospholipids (PL), free fatty acids (FFA), triacylglycerol (TAG) and cholesterol esters (CE) of adipocytes in different age rats with HFD-induced insulin resistance (IR) and its changes under N-stearoylethanolamine (NSE) administration. The experimental model was induced on rats in age 10-month-old and 24-month-old by 6-month HFD and confirmed by the oral glucose tolerance test. NSE was administrated as water suspension per os in a dosage 50 mg/kg daily during 2 weeks. Adipocytes were isolated from abdominal fat using Type 1 Collagenase solution. Adipocytes lipid extract was separated on the fractions by thin-layer chromatography. The fatty acid composition of lipid fractions was analyzed by gas-liquid chromatography. Experimental data were processed statistically using Student’s t-test. It was demonstrated, that prolonged HFD induces IR and leads to changes in FA profile of adipocytes PL, TAG, CE and composition of FFA in rats from two age groups. The results we obtained shoved that the aging process affects the fatty acid composition of adipocytes. Particularly, there was a significant decrease in the amount of fatty acids in the fractions of phospholipids, triacylglycerols and cholesterol esters together with a decrease in the percentage of unsaturated fatty acids. It was also demonstrated, that HFD significantly alters the fatty acid composition of all investigated adipocytes lipid fractions of younger age group rats, while similar changes were much less manifested in older age group of animals. NSE administration had a positive effect on the normalization of the fatty acid composition of the studied lipid fractions of both age group rat adipocytes. This study demonstrated that prolonged HFD induces obesity, increases the risk of type 2 diabetes development and leads to changes in adipocytes FA profile in rats from two age groups. As far as NSE administration had a positive effect on normalization of FA composition of adipocytes, we can consider NSE as a prospective agent for the treatment of obesity-induced complications and correction of age-related dyslipidemia.

The PPAR pan-agonist tetradecylthioacetic acid promotes redistribution of plasma cholesterol towards large HDL

Tetradecylthioacetic acid (TTA) is a synthetic fatty acid with a sulfur substitution in the β-position. This modification renders TTA unable to undergo complete β-oxidation and increases its biological activity, including activation of peroxisome proliferator activated receptors (PPARs) with preference for PPARα. This study investigated the effects of TTA on lipid and lipoprotein metabolism in the intestine and liver of mice fed a high fat diet (HFD). Mice receiving HFD supplemented with 0.75% (w/w) TTA had significantly lower body weights compared to mice fed the diet without TTA. Plasma triacylglycerol (TAG) was reduced 3-fold with TTA treatment, concurrent with increase in liver TAG. Total cholesterol was unchanged in plasma and liver. However, TTA promoted a shift in the plasma lipoprotein fractions with an increase in larger HDL particles. Histological analysis of the small intestine revealed a reduced size of lipid droplets in enterocytes of TTA treated mice, accompanied by increased mRNA expression of fatty acid transporter genes. Expression of the cholesterol efflux pump Abca1 was induced in the small intestine, but not in the liver. Scd1 displayed markedly increased mRNA and protein expression in the intestine of the TTA group. It is concluded that TTA treatment of HFD fed mice leads to increased expression of genes involved in uptake and transport of fatty acids and HDL cholesterol in the small intestine with concomitant changes in the plasma profile of smaller lipoproteins.

Urolithins Attenuate Multiple Symptoms of Obesity in Rats Fed on a High-Fat Diet

BACKGROUND

Urolithins are gut microbiota-derived polyphenol metabolites, produced following the consumption of pomegranate, berries, and nuts. Recent studies have shown the potentials of these metabolites on reducing triglycerides accumulation in cultured hepatocytes and adipocytes. In this study, we investigated the ability of both urolithin A (Uro-A) and urolithin B (Uro-B) to attenuate obesity and associated symptoms in a high-fat diet-induced obesity model in rats.

METHODS

Twenty-four male Wistar rats were randomly assigned to four groups. Group 1 was fed on a normal diet while groups 2, 3, and 4 were fed on a high-fat diet for 10 weeks. After this, groups 3 and 4 were treated with 2.5mg/kg body weight of Uro-A and Uro-B intraperitoneally, respectively. Body weight, serum lipid profile, hepatic antioxidant activity, hepatic lipid accumulation, fecal lipid content, and the expressions of genes involved in lipogenesis and hepatic ER stress were quantified.

RESULTS

Indeed, a high-fat diet resulted in increased body weight, visceral adipose tissue mass, and oxidative stress in rats. However, treatment with both Uro-A and Uro-B decreased body weight and visceral adipose tissue mass. These metabolites restored hepatic antioxidant capacity and decreased lipid accumulation in addition to an increase in fecal fat excretion. Moreover, both Uro-A and Uro-B treatment downregulated the expression of LXRα and SREBP1c; involved in de novo lipogenesis while upregulating PPARα expression for increased fatty acid oxidation. Furthermore, Uro-A and Uro-B decreased the expression of PERK and IRE1α; which are involved in hepatic ER stress. Taken together, our results showed the potentials of Uro-A and Uro-B in mitigating obesity symptoms and they could thus provide promising roles in the future as functional anti-obesity candidates.

Acetaminophen-Induced Liver Damage in Hepatic Steatosis

One of the most used painkillers is acetaminophen (APAP), which is safe at the right dose. However, several studies have described populations susceptible to APAP-induced liver damage, mainly in livers with steatosis. Thus, clinicians should consider the presence of obesity and other chronic liver diseases like nonalcoholic fatty liver disease (NAFLD) when indicating treatment with APAP. Liver damage from this drug is generated through its metabolite N-acetyl-p-benzoquinone imine, which is detoxified with glutathione (GSH). Prior depletion of GSH in steatotic hepatocytes plays a key role in APAP-induced hepatotoxicity in people with obesity and NAFLD. The knowledge about the damage to the liver or APAP in susceptible people like the obese and those with NAFLD is of great relevance for the sanitary sector because it would imply strategies of different therapeutic approach in such patients. This paper reviews the role of APAP in liver damage in the presence of obesity, NAFLD, and nonalcoholic steatohepatitis.

Lipidomic biomarkers and mechanisms of lipotoxicity in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) represents the most common form of chronic liver disease worldwide (about 25% of the general population) and 3-5% of patients develop non-alcoholic steatohepatitis (NASH), characterized by hepatocytes damage, inflammation and fibrosis, which increase the risk of developing liver failure, cirrhosis and hepatocellular carcinoma. The pathogenesis of NAFLD, particularly the mechanisms whereby a minority of patients develop a more severe phenotype, is still incompletely understood. In this review we examine the available literature on initial mechanisms of hepatocellular damage and inflammation, deriving from toxic effects of excess lipids. Accumulating data indicate that the total amount of triglycerides stored in the liver cells is not the main determinant of lipotoxicity and that specific lipid classes act as damaging agents. These lipotoxic species affect the cell behavior via multiple mechanisms, including activation of death receptors, endoplasmic reticulum stress, modification of mitochondrial function and oxidative stress. The gut microbiota, which provides signals through the intestine to the liver, is also reported to play a key role in lipotoxicity. Finally, we summarize the most recent lipidomic strategies utilized to explore the liver lipidome and its modifications in the course of NALFD. These include measures of lipid profiles in blood plasma and erythrocyte membranes that can surrogate to some extent lipid investigation in the liver.

Deciphering the Link Between Hyperhomocysteinemia and Ceramide Metabolism in Alzheimer-Type Neurodegeneration

Aging is one of the strongest risk factor for Alzheimer's disease (AD). However, several data suggest that dyslipidemia can either contribute or serve as co-factors in AD appearance. AD could be examined as a metabolic disorder mediated by peripheral insulin resistance. Insulin resistance is associated with dyslipidemia, which results in increased hepatic ceramide generation. Hepatic steatosis induces pro-inflammatory cytokine activation which is mediated by the increased ceramides production. Ceramides levels increased in cells due to perturbation in sphingolipid metabolism and upregulated expression of enzymes involved in ceramide synthesis. Cytotoxic ceramides and related molecules generated in liver promote insulin resistance, traffic through the circulation due to injury or cell death caused by local liver inflammation, and because of their hydrophobic nature, they can cross the blood-brain barrier and thereby exert neurotoxic responses as reducing insulin signaling and increasing pro-inflammatory cytokines. These abnormalities propagate a cascade of neurodegeneration associated with oxidative stress and ceramide generation, which potentiate brain insulin resistance, apoptosis, myelin degeneration, and neuro-inflammation. Therefore, excess of toxic lipids generated in liver can cause neurodegeneration. Elevated homocysteine level is also a risk factor for AD pathology and is narrowly associated with metabolic diseases and non-alcoholic fatty liver disease. The existence of a homocysteine/ceramides signaling pathway suggests that homocysteine toxicity could be partly mediated by intracellular ceramide accumulation due to stimulation of ceramide synthase. In this article, we briefly examined the role of homocysteine and ceramide metabolism linking metabolic diseases and non-alcoholic fatty liver disease to AD. We therefore analyzed the expression of mainly enzymes implicated in ceramide and sphingolipid metabolism and demonstrated deregulation of de novo ceramide biosynthesis and S1P metabolism in liver and brain of hyperhomocysteinemic mice.

Untargeted metabonomics reveals intervention effects of chicory polysaccharide in a rat model of non-alcoholic fatty liver disease

In the current study, serum metabolomics techniques were used to evaluate the potential mechanism of the effect of chicory polysaccharides in non-alcoholic fatty liver disease (NAFLD) rats. A rat model of NAFLD was constructed according to the histopathological data and biochemical parameters, while the underlying mechanisms of high-fat diet (HFD) induced NAFLD and the therapeutic effects of chicory polysaccharides (CP) were studied by the adoption of serum metabolomics. The serum metabolites were analyzed by GC/MS. Multivariate statistical approaches such as principal component analysis, revealed significant differences with HFD model and CP groups against the control. Results indicated that CP plays a regulatory role in the occurrence of NAFLD. Meantime, a total of 65 candidate biomarkers were screened and identified. Cluster analysis, enrichment analysis and metabolic pathway analysis of differential metabolites also indicated that amino acid metabolism and fatty acid biosynthesis in NAFLD rats, the β-oxidation and urea cycle of very long-chain fatty acids were mainly disturbed when compared against the control group. The corresponding metabolic pathways in the CP group were relieved compared against the NAFLD rats. These results showed that untargeted metabonomics helps to explain intervention effects of chicory polysaccharide with the rat model of NAFLD.

Oxidative Stress and Non-Alcoholic Fatty Liver Disease: Effects of Omega-3 Fatty Acid Supplementation

Aging is a complex phenomenon characterized by the progressive loss of tissue and organ function. The oxidative-stress theory of aging postulates that age-associated functional losses are due to the accumulation of ROS-induced damage. Liver function impairment and non-alcoholic fatty liver disease (NAFLD) are common among the elderly. NAFLD can progress to non-alcoholic steatohepatitis (NASH) and evolve to hepatic cirrhosis or hepatic carcinoma. Oxidative stress, lipotoxicity, and inflammation play a key role in the progression of NAFLD. A growing body of evidence supports the therapeutic potential of omega-3 polyunsaturated fatty acids (n-3 PUFA), mainly docosahaexenoic (DHA) and eicosapentaenoic acid (EPA), on metabolic diseases based on their antioxidant and anti-inflammatory properties. Here, we performed a systematic review of clinical trials analyzing the efficacy of n-3 PUFA on both systemic oxidative stress and on NAFLD/NASH features in adults. As a matter of fact, it remains controversial whether n-3 PUFA are effective to counteract oxidative stress. On the other hand, data suggest that n-3 PUFA supplementation may be effective in the early stages of NAFLD, but not in patients with more severe NAFLD or NASH. Future perspectives and relevant aspects that should be considered when planning new randomized controlled trials are also discussed.

Macronutrients and the Adipose-Liver Axis in Obesity and Fatty Liver

Macronutrient metabolism is a highly orchestrated process, with adipose tissue and liver each playing central roles in nutrient uptake, processing, transport, and storage. These 2 tissues form an important metabolic circuit, particularly as it relates to lipids as the primary storage form of excess energy. The function of the circuit is influenced by many factors, including the quantity and type of nutrients consumed and their impact on the overall health of the tissues. In this review we begin with a brief summary of the homeostatic disposition of lipids between adipose tissue and liver and how these processes can become dysregulated in obesity. We then explore how specific dietary nutrients and nutrient combinations can exert unique influences on the liver-adipose tissue axis.

Obestatin protects and reverses nonalcoholic fatty liver disease and its associated insulin resistance in rats via inhibition of food intake, enhancing hepatic adiponectin signaling, and blocking ghrelin acylation

This study investigated the ameliorative and protective effects of long-term obestatin administration (80 nmol/kg/ intraperitoneal injection (i.p.)) on the pathogenesis of high-fat diet (HFD) induced nonalcoholic fatty liver disease (NAFLD) in rats. Rats (n = 8/group) were divided as control, NAFLD, NAFLD + Simvastatin, NAFLD + obestatin, NAFLD then obestatin, and obestatin then NAFLD. Obestatin co -or post-therapy significantly reduced hepatomegaly and reversed hyperlipidemia, hepatic lipid accumulation, and insulin resistance (IR). Mechanistically obestatin treatments in these rats significantly prevented the increases in final body weights and food intake. Concomitantly, it enhanced circulatory adiponectin levels and hepatic signaling as evident by elevated hepatic protein levels of adiponectin receptors (adipoRII), carnitine palmitoyltransferase-1 (CPT-1), peroxisome proliferator-activated receptor- α (PPAR-α), and phosphor-AMPK (p-AMPK). In addition, obestatin enhanced total circulatory ghrelin levels and significantly increased deacylated ghrelin to acylated ghrelin (DAG/AG) ratio. These data suggest that obestatin reverses and protects against development or progression of NAFLD directly by modulating ghrelin and adiponectin signaling or indirectly by lowering food intake.

Betaine Supplementation Enhances Lipid Metabolism and Improves Insulin Resistance in Mice Fed a High-Fat Diet

Obesity is a major driver of metabolic diseases such as nonalcoholic fatty liver disease, certain cancers, and insulin resistance. However, there are no effective drugs to treat obesity. Betaine is a nontoxic, chemically stable and naturally occurring molecule. This study shows that dietary betaine supplementation significantly inhibits the white fat production in a high-fat diet (HFD)-induced obese mice. This might be due to betaine preventing the formation of new white fat (WAT), and guiding the original WAT to burn through stimulated mitochondrial biogenesis and promoting browning of WAT. Furthermore, dietary betaine supplementation decreases intramyocellular lipid accumulation in HFD-induced obese mice. Further analysis shows that betaine supplementation reduced intramyocellular lipid accumulation might be associated with increasing polyunsaturated fatty acids (PUFA), fatty acid oxidation, and the inhibition of fatty acid synthesis in muscle. Notably, by performing insulin-tolerance tests (ITTs) and glucose-tolerance tests (GTTs), dietary betaine supplementation could be observed for improvement of obesity and non-obesity induced insulin resistance. Together, these findings could suggest that inhibiting WAT production, intramyocellular lipid accumulation and inflammation, betaine supplementation limits HFD-induced obesity and improves insulin resistance.

Dietary fat stimulates development of NAFLD more potently than dietary fructose in Sprague-Dawley rats

BACKGROUND

In humans and animal models, excessive intake of dietary fat, fructose and cholesterol has been linked to the development of non-alcoholic fatty liver disease (NAFLD). However, the individual roles of the dietary components remain unclear. To investigate this further, we compared the effects of a high-fat diet, a high-fructose diet and a combination diet with added cholesterol on the development of NAFLD in rats.

METHODS

Forty male Sprague-Dawley rats were randomized into four groups receiving either a control-diet (Control: 10% fat); a high-fat diet (HFD: 60% fat, 20% carbohydrate), a high-fructose diet [HFr: 10% fat, 70% carbohydrate (mainly fructose)] or a high-fat/high-fructose/high-cholesterol-diet (NASH: 40% fat, 40% carbohydrate (mainly fructose), 2% cholesterol) for 16 weeks.

RESULTS

After 16 weeks, liver histology revealed extensive steatosis and inflammation in both NASH- and HFD-fed rats, while hepatic changes in HFr-rats were much more subtle. These findings were corroborated by significantly elevated hepatic triglyceride content in both NASH- (p < 0.01) and HFD-fed rats (p < 0.0001), elevated hepatic cholesterol levels in NASH-fed rats (p < 0.0001), but no changes in HFr-fed rats, compared to Control. On the contrary, only HFr-fed rats developed dyslipidemia as characterized by higher levels of plasma triglycerides compared to all other groups (p < 0.0001). Hepatic dysfunction and inflammation was confirmed in HFD-fed rats by elevated levels of hepatic MCP-1 (p < 0.0001), TNF-alpha (p < 0.001) and plasma β-hydroxybutyrate (p < 0.0001), and in NASH-fed rats by elevated levels of hepatic MCP-1 (p < 0.01), increased hepatic macrophage infiltration (p < 0.001), and higher plasma levels of alanine aminotransferase (p < 0.0001) aspartate aminotransferase (p < 0.05), haptoglobin (p < 0.001) and TIMP-1 (p < 0.01) compared to Control.

CONCLUSION

These findings show that dietary fat and cholesterol are the primary drivers of NAFLD development and progression in rats, while fructose mostly exerts its effect on the circulating lipid pool.

Perioperative oral supplementation with fish oil promotes liver regeneration following partial hepatectomy in mice via AMPK activation

The present study aimed to observe the effects of perioperative oral supplementation with fish oil (FO) on liver regeneration in mice and examine the potential mechanism. A total of 120 male ICR mice were randomly divided into 5 groups: Sham, Control, fish oil (FO), Compound C [the AMP‑activated protein kinase (AMPK) inhibitor dorsomorphin], and Compound C + FO. Changes in liver function, alterations in hepatocyte proliferation and in the expression of polarization markers, and activation of AMPK signaling were examined following partial hepatectomy (PH). The results demonstrated that restoration of serum alanine aminotransferase (ALT) and total bilirubin (TBIL) levels were significantly faster in FO‑treated mice compared with Control mice, and this effect was suppressed by treatment with Compound C. FO‑treated mice exhibited increased numbers of Ki‑67 positive hepatocytes and their postoperative liver‑to‑body weight ratio was significantly increased compared with the Control mice, which was also suppressed by co‑treatment with the AMPK inhibitor. Furthermore, protein expression of Occludin, Claudin‑3, tight junction protein 1 and bile salt export pump was gradually increased in FO‑treated mice compared with Control, whereas Compound C treatment reversed this effect. Therefore, the present study revealed that perioperative oral supplementation with FO may promote liver regeneration and improved liver function in mice following PH through AMPK activation.

Onset of decreased heart work is correlated with increased heart rate and shortened QT interval in high-carbohydrate fed overweight rats

Mechanical activity of the heart is adversely affected in metabolic syndrome (MetS) characterized by increased body mass and marked insulin resistance. Herein, we examined the effects of high carbohydrate intake on cardiac function abnormalities by evaluating in situ heart work, heart rate, and electrocardiograms (ECGs) in rats. MetS was induced in male Wistar rats by adding 32% sucrose to drinking water for 22–24 weeks and was confirmed by insulin resistance, increased body weight, increased blood glucose and serum insulin, and increased systolic and diastolic blood pressures in addition to significant loss of left ventricular integrity and increased connective tissue around myofibrils. Analysis of in situ ECG recordings showed a markedly shortened QT interval and decreased QRS amplitude with increased heart rate. We also observed increased oxidative stress and decreased antioxidant defense characterized by decreases in serum total thiol level and attenuated paraoxonase and arylesterase activities. Our data indicate that increased heart rate and a shortened QT interval concomitant with higher left ventricular developed pressure in response to β-adrenoreceptor stimulation as a result of less cyclic AMP release could be regarded as a natural compensation mechanism in overweight rats with MetS. In addition to the persistent insulin resistance and obesity associated with MetS, one should consider the decreased heart work, increased heart rate, and shortened QT interval associated with high carbohydrate intake, which may have more deleterious effects on the mammalian heart.

Fibronectin Type III Domain-Containing Protein 5 rs3480 A>G Polymorphism, Irisin, and Liver Fibrosis in Patients With Nonalcoholic Fatty Liver Disease

CONTEXT

Contrasting data have been reported on the role of irisin, a novel myokine encoded by the fibronectin type III domain-containing protein 5 (FNDC5) gene, in nonalcoholic fatty liver disease (NAFLD) pathogenesis. We tested in patients with suspected nonalcoholic steatohepatitis (NASH) the association of FNDC5 variants, hepatic expression, and circulating irisin with liver damage (F2 to F4 fibrosis as main outcome). We also investigated whether irisin modulates hepatocellular fat accumulation and stellate cell activation in experimental models.

METHODS

We considered 593 consecutive patients who underwent liver biopsy for suspected NASH and 192 patients with normal liver enzymes and without steatosis. FNDC5 rs3480 and rs726344 genotypes were assessed by 5' nuclease assays. Hepatic irisin expression was evaluated in mice fed a high-fat diet or treated with CCl4. The effect of irisin was evaluated in fat-laden HepG2 hepatocytes and in hepatic stellate cells (HSCs).

RESULTS

In patients at risk for NASH [odds ratio (OR) = 0.64, 95% confidence interval (CI), 0.47 to 0.87; P = 0.005], and more so in the high-risk subgroup of those with impaired fasting glucose/diabetes (OR = 0.44, 95% CI, 0.26 to 0.74; P = 0.002), the rs3480 A>G variant was independently associated with protection from F2 to F4 fibrosis. Irisin is expressed in human activated HSC, where it mediated fibrogenic actions and collagen synthesis, and is overexpressed in NAFLD patients with F2 to F4 fibrosis and CCl4-treated mice. However, Irisin does not affect fat accumulation in HepG2 and is not induced by high-fat-diet-inducing NAFLD.

CONCLUSIONS

The FNDC5 rs3480 variant is associated with protection from clinically significant fibrosis in patients with NAFLD, while irisin expression is correlated with the severity of NAFLD and may be involved in extracellular matrix deposition. These data suggest that irisin is involved in regulation of hepatic fibrogenesis.

Nonalcoholic fatty liver disease impairs the cytochrome P-450-dependent metabolism of α-tocopherol (vitamin E)

This study aims to investigate in in vivo and in vitro models of nonalcoholic fatty liver disease (NAFLD) the enzymatic metabolism of α-tocopherol (vitamin E) and its relationship to vitamin E-responsive genes with key role in the lipid metabolism and detoxification of the liver. The experimental models included mice fed a high-fat diet combined or not with fructose (HFD+F) and HepG2 human hepatocarcinoma cells treated with the lipogenic agents palmitate, oleate or fructose. CYP4F2 protein, a cytochrome P-450 isoform with proposed α-tocopherol ω-hydroxylase activity, decreased in HFD and even more in HFD+F mice liver; this finding was associated with increased hepatic levels of α-tocopherol and decreased formation of the corresponding long-chain metabolites α-13-hydroxy and α-13-carboxy chromanols. A decreased expression was also observed for PPAR-γ and SREBP-1 proteins, two vitamin E-responsive genes with key role in lipid metabolism and CYP4F2 gene regulation. A transient activation of CYP4F2 gene followed by a repression response was observed in HepG2 cells during the exposure to increasing levels of the lipogenic and cytotoxic agent palmitic acid; such gene repression effect was further exacerbated by the co-treatment with oleic acid and α-tocopherol and was also observed for PPAR-γ and the SREBP isoforms 1 and 2. Such gene response was associated with increased uptake and ω-hydroxylation of α-tocopherol, which suggests a minor role of CYP4F2 in the enzymatic metabolism of vitamin E in HepG2 cells. In conclusion, the liver metabolism and gene response of α-tocopherol are impaired in experimental NAFLD.

Enteral High Fat-Polyunsaturated Fatty Acid Blend Alters the Pathogen Composition of the Intestinal Microbiome in Premature Infants with an Enterostomy

OBJECTIVE

To determine the effect of enteral fish oil and safflower oil supplementation on the intestinal microbiome in infants with an enterostomy born premature.

STUDY DESIGN

Infants with an enterostomy born premature were randomized to receive early enteral supplementation with a high-fat polyunsaturated fatty acid (HF-PUFA) blend of fish oil and safflower oil vs standard nutritional therapy. We used 16S rRNA gene sequencing for longitudinal profiling of the microbiome from the time of study entry until bowel reanastomosis. We used weighted gene coexpression network analysis to identify microbial community modules that differed between study groups over time. We performed imputed metagenomic analysis to determine metabolic pathways associated with the microbial genes.

RESULTS

Sixteen infants were randomized to receive enteral HF-PUFA supplementation, and 16 infants received standard care. The intestinal microbiota of infants in the treatment group differed from those in the control group, with greater bacterial diversity and lower abundance of Streptococcus, Clostridium, and many pathogenic genera within the Enterobacteriaceae family. We identified 4 microbial community modules with significant differences between groups over time. Imputed metagenomic analysis of the microbial genes revealed metabolic pathways that differed between groups, including metabolism of amino acids, carbohydrates, fatty acids, and secondary bile acid synthesis.

CONCLUSION

Enteral HF-PUFA supplementation was associated with decreased abundance of pathogenic bacteria, greater bacterial diversity, and shifts in the potential metabolic functions of intestinal microbiota.

TRIAL REGISTRATION

ClinicalTrials.gov:NCT01306838.

Ameliorative effects of Compound K and ginsenoside Rh1 on non-alcoholic fatty liver disease in rats

Non-alcoholic fatty liver disease (NAFLD) is a common liver disease, which has no standard treatment available. Panax notoginseng saponines (PNS) have recently been reported to protect liver against hepatocyte injury induced by ethanol or high fat diet (HFD) in rats. Compound K and ginsenoside Rh1 are the main metabolites of PNS. In this study, we evaluated the effects of CK and Rh1 on NAFLD. Rats fed HFD showed significant elevations in liver function markers, lipids, glucose tolerance, and insulin resistance. Treatment with CK or Rh1 either alone or in combination dramatically ameliorated the liver function impairment induced by HFD. Histologically, CK and Rh1 significantly reversed HFD-induced hepatocyte injury and liver fibrosis. In vitro experiments demonstrated that treatment with CK or Rh1 alone or in combination markedly induced cell apoptosis, and inhibited cell proliferation and activation in HSC-T6 cells. Additionally, CK and Rh1, either alone or in combination, also repressed the expression of fibrotic factors TIMP-1, PC-I, and PC-III. Taken together, our results demonstrate that CK and Rh1 have positive effects on NAFLD via the anti-fibrotic and hepatoprotective activity.

Animal Models of Nonalcoholic Steatohepatitis: Eat, Delete, and Inflame

With the obesity epidemic, nonalcoholic fatty liver disease (NAFLD) has become a public health problem with increasing prevalence. The mechanism of disease progression remains obscure and effective therapy is lacking. Therefore, there is a need to understand the pathogenic mechanisms responsible for disease development and progression in order to develop innovative therapies. To accomplish this goal, experimental animal models that recapitulate the human disease are necessary, especially, since causative mechanistic studies of NAFLD are more difficult or unethical to perform in humans. A large number of studies regarding the pathophysiology and treatment of nonalcoholic steatohepatitis (NASH) have been undertaken in mice to model human NAFLD and NASH. This review discusses the known dietary, genetic, and inflammation-based animal models of NASH described in recent years, with a focus on the major advances made in this field.

Emerging Therapies for Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease is the most common cause of liver disease in the United States. There are no drug therapies approved for the treatment of nonalcoholic steatohepatitis (NASH). Multiple different pathways are involved in the pathogenesis and each can be the target of the therapy. It is possible that more than 1 target is involved in disease development and progression. Multiple clinical trials with promising agents are underway. Because NASH is a slowly progressive disease and treatment likely to be of prolonged duration, acceptance and approval of any agent will require information on long-term clinical benefits and safety.

Extract of a polyherbal formulation ameliorates experimental nonalcoholic steatohepatitis

The objective of the present study is to evaluate the effect of the extract of a well-known hepatospecific polyherbal formulation, Liv.52, in an experimental model of high-fat diet (HFD)-induced nonalcoholic steatohepatitis (NASH) in rats. Feeding a HFD for 15 weeks resulted in significant impairment of the lipid profile, elevation of hepatic enzyme markers, and insulin resistance in rats. The histological examination of the liver furthermore indicated fibrotic changes and fat deposition in hepatic tissues. The treatment with Liv.52 extract [125 mg/kg body weight per os (b.wt. p.o.)], which was administered from week 9 onward, reversed the HFD-induced changes to a statistically significant extent, compared to the untreated positive control animals. The effect observed with Liv.52 extract was comparable to that of pioglitazone (4 mg/kg b.wt.), a standard drug that is useful in the management of NASH. The treatment with Liv.52 extract significantly reduced steatosis, collagen deposition, and necrosis in hepatic tissues, which indicates its antifibrotic and antinecrotic properties. The results obtained in the present set of experiments indicate that Liv.52 extract effectively reverses metabolic and histological changes associated with HFD-induced NASH.

Alcoholic vs non-alcoholic fatty liver in rats: distinct differences in endocytosis and vesicle trafficking despite similar pathology

Background

Non-alcoholic and alcoholic fatty liver disease (NAFLD and AFLD, respectively) are major health problems, as patients with either condition can progress to hepatitis, fibrosis, and cirrhosis. Although histologically similar, key differences likely exist in these two models. For example, altered content of several vesicle trafficking proteins have been identified in AFLD, but their content in NAFLD is unknown. In this study, we compared select parameters in NAFLD and AFLD in a rat model.

Methods

We fed either Lieber- DeCarli liquid control or alcohol-containing (35 % as calories) diet (AFLD model) or lean or high-fat (12 or 60 % derived from fat, respectively) pellets (NAFLD model) for 8–10 weeks, n = 8 in each model. Serum, hepatocytes and liver tissue were analyzed. Liver injury markers were measured in serum, triglyceride content and endocytosis (binding and internalization of ¹²⁵I- asialoorosomucoid) was measured in isolated hepatocytes, and content of selected trafficking proteins (Rab3D, Rab7 and Rab18) were determined in whole liver tissue.

Results

Although liver injury markers and triglyceride content were similar in both models, binding and internalization of ¹²⁵I- asialoorosomucoid was significantly impaired in the hepatocytes from AFLD, but not NAFLD, animals. In addition, protein content of the asialoglycoprotein receptor (ASGPR) and three trafficking proteins, Rab3D, Rab7and Rab18, were significantly decreased after alcohol, but not high-fat feeding. Levels of protein carbonylation, amount of glutathione stores, and lipid peroxidation were similar irrespective of the insult to the livers that resulted in fatty liver.

Conclusion

Impairments in protein trafficking in AFLD are likely a direct result of alcohol administration, and not a function of fatty liver.