HFD-induced Nonalcoholic Fatty Liver Disease Research Articles

Nimesulide, a cyclooxygenase-2 selective inhibitor, suppresses obesity-related non-alcoholic fatty liverdisease and hepatic insulin resistance through the regulation ofperoxisome proliferator-activated receptor γ.

Cyclooxygenase (COX)-2 selective inhibitors suppress non-alcoholic fatty liver disease (NAFLD); however, the precise mechanism of action remains unknown. The aim of this study was to examine how the COX-2 selective inhibitor nimesulide suppresses NAFLD in a murine model of high-fat diet (HFD)-induced obesity. Mice were fed either a normal chow diet (NC), an HFD, or HFD plus nimesulide (HFD-nime) for 12 weeks. Body weight, hepatic COX-2 mRNA expression and triglyceride accumulation were significantly increased in the HFD group. Triglyceride accumulation was suppressed in the HFD-nime group. The mRNA expression of hepatic peroxisome proliferator-activated receptor γ (PPARγ) and the natural PPARγ agonist 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) were significantly increased in the HFD group and significantly suppressed in the HFD-nime group. Glucose metabolism was impaired in the HFD group compared with the NC group, and it was significantly improved in the HFD-nime group. In addition, the plasma insulin levels in the HFD group were increased compared with those in the NC group, and were decreased in the HFD-nime group. These results indicate that HFD-induced NAFLD is mediated by the increased hepatic expression of COX-2. We suggest that the production of 15d-PGJ2, which is mediated by COX-2, induces NAFLD and hepatic insulin resistance by activating PPARγ. Furthermore, the mRNA expression of tissue inhibitor of metalloproteinases-1 (TIMP-1), procollagen-1 and monocyte chemoattractant protein-1 (MCP-1), as well as the number of F4/80-positive hepatic (Kupffer) cells, were significantly increased in the HFD group compared with the NC group, and they were reduced by nimesulide. In conclusion, COX-2 may emerge as a molecular target for preventing the development of NAFLD and insulin resistance in diet-related obesity.

New insights into salvianolic acid A action: Regulation of the TXNIP/NLRP3 and TXNIP/ChREBP pathways ameliorates HFD-induced NAFLD in rats.

Salvianolic acid A (SalA), one of the most efficacious polyphenol compounds extracted from Radix Salvia miltiorrhiza (Danshen), has been shown to possess many potential pharmacological activities. This study aimed to investigate whether SalA has hepatoprotective effects against high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) and to further explore the mechanism underlying this process. SalA treatment significantly attenuated HFD-induced obesity and liver injury, and markedly decreased lipid accumulation in HFD-fed rat livers. Moreover, SalA treatment ameliorated HFD-induced hepatic inflammation and oxidative stress by decreasing hepatotoxic levels of cytokines, suppressing the overproduction of reactive oxygen species (ROS) and methane dicarboxylic aldehyde (MDA) and preventing the decreased expression of superoxide dismutase (SOD). Importantly, SalA reversed the HFD- or palmitic acid (PA)-induced activation of the NLRP3 inflammasome, the nuclear translocation of ChREBP and the up-regulation of FAS, and these effects were accompanied by TXNIP down-regulation. However, TXNIP siRNA treatment partially abrogated the above-mentioned effects of SalA in PA-treated HepG2 cells. Together, our results demonstrated, for the first time, that SalA protects against HFD-induced NAFLD by ameliorating hepatic lipid accumulation and inflammation, and these protective effects may partially due to regulation of the TXNIP/NLRP3 and TXNIP/ChREBP pathways.

Ameliorative Effects of Pomegranate Peel Extract against Dietary-Induced Nonalcoholic Fatty Liver in Rats.

Non-alcoholic fatty liver disease (NAFLD) is caused by fat accumulation and is associated with oxidative stress. In this study, we investigated the potential protective effect of pomegranate (Punica granatum L.) peel extract (PPE) against oxidative stress in the liver of rats with NAFLD. Sprague-Dawley rats were fed a high fat diet (HFD), 20% corn oil, or palm oil for 8 weeks in the presence or absence of PPE. The control group was fed a basal diet. The progression of NAFLD was evaluated histologically and by measuring liver enzymes (alanine transaminase and aspartate transaminase), serum lipids (triglycerides and total cholesterol), and oxidative stress markers. The HFD feeding increased the body weight and caused NAFLD, liver steatosis, hyperlipidemia, oxidative stress, and elevated liver enzymes. Administration of PPE ameliorated the hepatic morphology, reduced body weight, improved liver enzymes, and inhibited lipogenesis. Furthermore, PPE enhanced the cellular redox status in the liver tissue of rats with NAFLD. Our findings suggest that PPE could improve HFD-induced NAFLD via abolishment of hepatic oxidative damage and hyperlipidemia. PPE might be considered as a potential lead material in the treatment of NAFLD and obesity through the modulation of lipid metabolism.

Adipose tissue-derived stem cells promote the reversion of non-alcoholic fatty liver disease: An in vivo study.

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of liver injury and seriously affects human health. In the present study, we aimed to investigate whether adipose tissue-derived stem cell (ADSC) transplantation in combination with dietary modification was capable of reversing the progression of NAFLD. After establishing a rat model of NAFLD by feeding them a high-fat diet (HFD), ADSCs were transplanted via the portal vein into rats with HFD-induced NAFLD, and simultaneously fed a modified diet. Thereafter, gross liver morphology, the hepatosomatic (HSI) index and indicators of liver function, including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) were evaluated. Subsequently, the serum levels of total cholesterol (TC), triglycerides (TGs) and fatty acids (FAs) were also assayed. Furthermore, H&E and oil red O staining were used to confirm the pathological effects of NAFLD in the rat livers. Although dietary modification alone caused liver function to recover, ADSC transplantation in combination with dietary modification further decreased the HSI index, the serum levels of ALT, TBIL, TC, TGs, FAs, reduced lipid accumulation to normal levels, and reversed the hepatic pathological changes in the rat livers. Taken together, these findings suggest that ADSC transplantation assists in the reversion of NAFLD by improving liver function and promoting lipid metabolism, thereby exerting hepatoprotective effects. Thus, we suggest that ADSC transplantation is a promising, potential therapeutic strategy for NAFLD treatment.

Coral calcium hydride prevents hepatic steatosis in high fat diet-induced obese rats: A potent mitochondrial nutrient and phase II enzyme inducer

Diet-induced nonalcoholic fatty liver disease (NAFLD) is characterized by profound lipid accumulation and associated with an inflammatory response, oxidative stress and hepatic mitochondrial dysfunction. We previously demonstrated that some mitochondrial nutrients effectively ameliorated high fat diet (HFD)-induced hepatic steatosis and metabolic disorders. Molecular hydrogen in hydrogen-rich liquid or inhaling gas, which has been confirmed in scavenging reactive oxygen species and preventing mitochondrial decay, improved metabolic syndrome in patients and animal models. Coral calcium hydride (CCH) is a new solid molecular hydrogen carrier made of coral calcium. However, whether and how CCH impacts HFD-induced hepatic steatosis remains uninvestigated. In the present study, we applied CCH to a HFD-induced NAFLD rat model for 13weeks. We found that CCH durably generated hydrogen in vivo and in vitro. CCH treatment significantly reduced body weight gain, improved glucose and lipid metabolism and attenuated hepatic steatosis in HFD-induced obese rats with no influence on food and water intake. Moreover, CCH effectively improved HFD-induced hepatic mitochondrial dysfunction, reduced oxidative stress, and activated phase II enzymes. Our results suggest that CCH is an efficient hydrogen-rich agent, which could prevent HFD-induced NAFLD via activating phase II enzymes and improving mitochondrial function.

Effect of Alkaloids from Nelumbinis Plumula against Insulin Resistance of High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease in Mice.

This study aimed to investigate the effects of total alkaloids from Nelumbinis Plumula (NPA) on insulin resistance (IR) of high-fat diet- (HFD-) induced nonalcoholic fatty liver disease (NAFLD). Rats were fed with HFD for 8 weeks to induce NAFLD. Then, the effect of NPA on ameliorating IR in HFD-induced NAFLD was evaluated. Fasting serum insulin was determined using an enzyme-linked immunosorbent assay (ELISA) kit for insulin following the manufacturer's protocol. Some inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) were determined using ELISA kits to assess the inflammatory burden in rats. The results showed that HFD could induce a significant increase in blood glucose and IR in rats. However, rats treated with NPA (400 or 600 mg/kg) showed improved IR and reduction in serum inflammatory cytokines TNF-α and IL-6. Further investigation indicated that NPA could inhibit IR by restoring the insulin receptor substrate-1 (IRS-1) and suppressing the expression of c-Jun N-terminal kinase (JNK) phosphorylation. The present results supported the view that the pathogenesis of NAFLD was complex with inflammation, together with increasing serum glucose and IR. Also, JNK and IRS phosphorylation were suggested for their involvement in the modulating of IR during NAFLD progression. Therefore, NPA may serve as a potential natural remedy against IR in NAFLD.

Perilla Oil Has Similar Protective Effects of Fish Oil on High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease and Gut Dysbiosis.

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease in developed countries. Recent studies indicated that the modification of gut microbiota plays an important role in the progression from simple steatosis to steatohepatitis. Epidemiological studies have demonstrated consumption of fish oil or perilla oil rich in n-3 polyunsaturated fatty acids (PUFAs) protects against NAFLD. However, the underlying mechanisms remain unclear. In the present study, we adopted 16s rRNA amplicon sequencing technique to investigate the impacts of fish oil and perilla oil on gut microbiomes modification in rats with high-fat diet- (HFD-) induced NAFLD. Both fish oil and perilla oil ameliorated HFD-induced hepatic steatosis and inflammation. In comparison with the low-fat control diet, HFD feeding significantly reduced the relative abundance of Gram-positive bacteria in the gut, which was slightly reversed by either fish oil or perilla oil. Additionally, fish oil and perilla oil consumption abrogated the elevated abundance of Prevotella and Escherichia in the gut from HFD fed animals. Interestingly, the relative abundance of antiobese Akkermansia was remarkably increased only in animals fed fish oil compared with HFD group. In conclusion, compared with fish oil, perilla oil has similar but slightly weaker potency against HFD-induced NAFLD and gut dysbiosis.

Molecular Alterations in a High-Fat Mouse Model Before the Onset of Diet–Induced Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases worldwide. However, the precise mechanism of the disease and a definitive treatment has not yet been discovered. Studies on NAFLD frequently use an animal model fed a high-fat diet (HFD) for 24 to 48 weeks. While full-blown liver inflammation and fibrosis occur after 24 weeks of HFD administration, changes in the liver at earlier time points have not been rigorously investigated. We hypothesized that there would be some molecular alterations at an earlier time point that would predict the later onset of pathologic symptoms. The aim of our study was to delineate the changes that take place before the pathologically detectable NAFLD appears in HFD mice, which would facilitate more effective study and treatment of NAFLD. We fed C57BL/6 mice a high-fat diet for 8 to 24 weeks and evaluated liver fat accumulation, inflammation, and fibrosis. Significant pathologic fat content, inflammation, and fibrosis in the liver could only be noticed after 24 weeks of HFD. However, we observed dysregulated immune function as early as 8 weeks after the start of the diet, and detected molecular changes associated with fat accumulation by week 12. Symptoms related to liver fibrosis were the most delayed changes. Our results suggest that alterations in inflammation and fat metabolism are early changes, followed by liver fibrosis in the HFD-induced NAFLD animal model. Therefore, future NAFLD experiments using this model can be designed to include earlier time points at which the desired HFD-induced alterations occur, and NAFLD experiments that aim to investigate immunologic alterations may be performed after a shorter duration of HFD feeding.

Untargeted Metabolomics Reveals Intervention Effects of Total Turmeric Extract in a Rat Model of Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is one of the most common forms of chronic liver disease. Currently, there are no recognized medical therapies effective for NAFLD. Previous studies have demonstrated the effects of total turmeric extract on rats with NAFLD induced by high-fat diet. In this study, serum metabolomics was employed using UHPLC-Q-TOF-MS to elucidate the underlying mechanisms of HFD-induced NAFLD and the therapeutic effects of TE. Supervised orthogonal partial least-squares-discriminant analysis was used to discover differentiating metabolites, and pathway enrichment analysis suggested that TE had powerful combined effects of regulating lipid metabolism by affecting glycerophospholipid metabolism, glycerolipid metabolism, and steroid hormone biosynthesis signaling pathways. In addition, the significant changes in glycerophospholipid metabolism proteins also indicated that glycerophospholipid metabolism might be involved in the therapeutic effect of TE on NAFLD. Our findings not only supply systematic insight into the mechanisms of NAFLD but also provide a theoretical basis for the prevention or treatment of NAFLD.

Fucoidan ameliorates steatohepatitis and insulin resistance by suppressing oxidative stress and inflammatory cytokines in experimental non-alcoholic fatty liver disease.

Fucoidan, a sulfated polysaccharide derived from brown seaweeds, possesses a wide range of pharmacological properties. In the present study, we investigated the therapeutic effect of fucoidan on non-alcoholic fatty liver disease (NAFLD) in rats. Rats were fed a high-fat diet (HFD) for 12 weeks to induce NAFLD. Oral administrations of fucoidan (100mg/kg, orally), metformin (200mg/kg, orally) or the vehicle were started in the last four weeks. Results showed that administration of fucoidan for 4 weeks attenuated the development of NAFLD as evidenced by the significant decrease in liver index, serum liver enzymes activities, serum total cholesterol and triglycerides, fasting serum glucose, insulin, insulin resistance, and body composition index. Further, fucoidan decreased hepatic malondialdehyde as well as nitric oxide concentrations, and concomitantly increased hepatic reduced glutathione level. In addition, the effect of fucoidan was accompanied with significant decrease in hepatic mRNA expressions of tumor necrosis factor-α, interleukins-1β and matrix metalloproteinase-2. Furthermore, histopathological examination confirmed the effect of fucoidan. In conclusion, fucoidan ameliorated the development of HFD-induced NAFLD in rats that may be, at least partly, related to its hypolipidemic, insulin sensitizing, antioxidant and anti-inflammatory mechanisms.

Inhibition of Advanced Glycation Endproduct Formation by Lotus Seedpod Oligomeric Procyanidins through RAGE-MAPK Signaling and NF-κB Activation in High-Fat-Diet Rats.

This study investigated the protective properties of lotus seedpod oligomeric procyanidins (LSOPC) against nonalcoholic fatty liver disease (NAFLD) and its underlying mechanism. Sprague-Dawley (SD) male rats were fed a basic diet, a high-fat diet (HFD), or HFD plus 0.2 or 0.5% (w/w) LSOPC for 12 weeks. Administration of LSOPC markedly reduced serum and hepatic biochemical parameters and protein expression of advanced glycation endproducts (AGEs). Additionally, 0.5% (w/w) LSOPC treatment remarkably reversed the increasing tendency of receptor of advanced glycation endproduct (RAGE) to normal level. Furthermore, dietary LSOPC significantly decreased the protein levels of mitogen-activated protein kinases (MAPK) and nuclear factor-kappa B (NF-κB) and down-regulated genes involved in pro-inflammatory cytokines and adhesion molecules. Taken together, these findings demonstrate that LSOPC may protect obese rats with long-term HFD-induced NAFLD against RAGE-MAPK-NF-κB signaling suppression.

Protective effects of Ginkgo biloba leaf polysaccharide on nonalcoholic fatty liver disease and its mechanisms

A water-soluble polysaccharide fraction extracted from the leaf of Ginkgo biloba was named GBLP. The protective effect of GBLP on nonalcoholic fatty liver disease (NAFLD) was observed and underlying mechanism was explored. Wistar male rats were randomly divided into five groups, namely, normal control group, model control group and GBLP groups (100, 200 and 400mg/kg/d). A rat model of NAFLD was established in male Wistar rats by feeding with high-fat diet (HFD) for 8 weeks. On day 57, the intragastric administration of GBLP started once daily for 4 weeks. The results showed that GBLP supplementation significantly and dose-dependently lowered the weight gain of body, liver index and serum lipid parameters in HFD-fed rat. Meanwhile, GBLP attenuated HFD-induced liver injury through reducing hepatic steatosis, TG accumulation, serum ALT, AST and ALP levels. GBLP had a positive effect on obesity-associated insulin resistance (IR) via reducing serum glucose and insulin levels. Furthermore, GBLP enhanced the activities of antioxidant enzymes and reduced MDA levels in serum and liver. These results indicate that GBLP can play a certain protective role against HFD-induced NAFLD, and the protective effects may be associated with attenuating IR, preserving liver function, enhancing antioxidant defense system, and reducing lipid peroxidation.

Hepatic STAMP2 alleviates high fat diet-induced hepatic steatosis and insulin resistance

Most studies on the role of STAMP2 in metabolism have used adipose tissue. Little knowledge exists concerning the role of STAMP2 in the liver, which is a metabolically central target. We hypothesized that STAMP2 is involved in non-alcoholic fatty liver disease (NAFLD) pathogenesis. We examined our hypothesis using human NAFLD patient pathology samples and a high-fat diet (HFD)-induced NAFLD mouse model. The molecular mechanism underlying hepatic STAMP2-mediated lipid imbalance was explored using an oleic acid (OA)-induced NAFLD in vitro model. Noticeably, the expression level of STAMP2 protein was reduced in the livers obtained from NAFLD patients and HFD-induced NAFLD mice. In vivo knockdown of hepatic STAMP2 by siRNA accelerated hepatic steatosis and insulin resistance in mice fed a HFD. Conversely, the delivery of adenoviral STAMP2 (Ad-STAMP2) improved hepatic steatosis in HFD-induced NAFLD mice. The expression of lipogenic or adipogenic factors was increased in both in vitro and in vivo NAFLD models but was reversed by Ad-STAMP2. Adenoviral overexpression of STAMP2 improved insulin resistance in the HFD-induced NAFLD mice. In vivo and in vitro assays demonstrated that STAMP2 modulates insulin sensitivity and glucose metabolism and that STAMP2 counteracts OA-induced insulin resistance by modulating insulin receptor substrate-1 stability. The present study revealed that hepatic STAMP2 plays a pivotal role in preventing HFD-induced NAFLD and that STAMP2 overexpression improves hepatic steatosis and insulin resistance in NAFLD. Our findings indicate that STAMP2 may represent a suitable target for interventions targeting NAFLD.

Rimonabant Improves Oxidative/Nitrosative Stress in Mice with Nonalcoholic Fatty Liver Disease.

The present study deals with the effects of rimonabant on oxidative/nitrosative stress in high diet- (HFD-) induced experimental nonalcoholic fatty liver disease (NAFLD). Male mice C57BL/6 were divided into the following groups: control group fed with control diet for 20 weeks (C; n = 6); group fed with HFD for 20 weeks (HF; n = 6); group fed with standard diet and treated with rimonabant after 18 weeks (R; n = 9); group fed with HFD and treated with rimonabant after 18 weeks (HFR; n = 10). Daily dose of rimonabant (10 mg/kg) was administered to HFR and R group by oral gavage for two weeks. Treatment induced a decrease in hepatic malondialdehyde concentration in HFR group compared to HF group (P < 0.01). The concentration of nitrites + nitrates in liver was decreased in HFR group compared to HF group (P < 0.01). Liver content of reduced glutathione was higher in HFR group compared to HF group (P < 0.01). Total liver superoxide dismutase activity in HFR group was decreased in comparison with HF group (P < 0.01). It was found that rimonabant may influence hepatic iron, zinc, copper, and manganese status. Our study indicates potential usefulness of cannabinoid receptor type 1 blockade in the treatment of HFD-induced NAFLD.

Intestinal farnesoid X receptor signaling promotes nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) is a major worldwide health problem. Recent studies suggest that the gut microbiota influences NAFLD pathogenesis. Here, a murine model of high-fat diet-induced (HFD-induced) NAFLD was used, and the effects of alterations in the gut microbiota on NAFLD were determined. Mice treated with antibiotics or tempol exhibited altered bile acid composition, with a notable increase in conjugated bile acid metabolites that inhibited intestinal farnesoid X receptor (FXR) signaling. Compared with control mice, animals with intestine-specific Fxr disruption had reduced hepatic triglyceride accumulation in response to a HFD. The decrease in hepatic triglyceride accumulation was mainly due to fewer circulating ceramides, which was in part the result of lower expression of ceramide synthesis genes. The reduction of ceramide levels in the ileum and serum in tempol- or antibiotic-treated mice fed a HFD resulted in downregulation of hepatic SREBP1C and decreased de novo lipogenesis. Administration of C16:0 ceramide to antibiotic-treated mice fed a HFD reversed hepatic steatosis. These studies demonstrate that inhibition of an intestinal FXR/ceramide axis mediates gut microbiota-associated NAFLD development, linking the microbiome, nuclear receptor signaling, and NAFLD. This work suggests that inhibition of intestinal FXR is a potential therapeutic target for NAFLD treatment.

Effect of oleoylethanolamide on diet-induced nonalcoholic fatty liver in rats

Oleoylethanolamine (OEA), an endogenous high-affinity agonist of peroxisome proliferator-activated receptor alpha (PPAR-α), has revealed the pharmacological properties in the treatment of obesity, atherosclerosis and other diseases through the modulation of lipid metabolism. To assess whether OEA can also regulate non-alcoholic fatty liver disease (NAFLD) caused by fat accumulation, we administrated OEA or fenofibrate in Sprague Dawley (SD) rats fed with a high fat diet (HFD). After 6 or 17 weeks treatment, OEA (5 mg/kg/day, i.p.) relieved the development of NAFLD compared with control groups by regulating the levels of plasma TG, TC, ALT and AST and liver inflammatory cytokines. Gene expression analysis of liver tissue and plasma from the animal models showed that OEA and fenofibrate both promoted the lipid β-oxidation by activating PPAR-α. Detailed research revealed that OEA inhibited the mRNA expression of lipogenesis in a PPAR-α-independant manner, while fenofibrate expressed an opposite effection. In summary, our research results suggested that as a potential lead compound, OEA could improve HFD-induced NAFLD with higher efficacy and safety than fenofibrate.

Troxerutin improves hepatic lipid homeostasis by restoring NAD+-depletion-mediated dysfunction of lipin 1 signaling in high-fat diet-treated mice

Recent evidences suggest that NAD+ depletion leads to abnormal hepatic lipid metabolism in high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD); however, the contributing mechanism is not well understood. Our previous study showed that troxerutin, a trihydroxyethylated derivative of natural bioflavonoid rutin, effectively inhibited obesity, and normalized hyperglycemia and hyperlipidemia in high-cholesterol diet-induced diabetic mice. Here we investigated whether troxerutin improved hepatic lipid metabolism via preventing NAD+ depletion in HFD-induced NAFLD mouse model and the mechanisms underlying these effects. Our results showed that troxerutin markedly prevented obesity, liver steatosis and injury in HFD-fed mice. Troxerutin largely suppressed oxidative stress-mediated NAD+-depletion by increasing nicotinamide phosphoribosyltransferase (NAMPT) protein expression and decreasing poly (ADP-ribose) polymerase-1 (PARP1) protein expression and activity in HFD-treated mouse livers. Consequently, troxerutin remarkably restored Silent mating type information regulation 2 homolog1 (SirT1) protein expression and activity in HFD-treated mouse livers. Therefore, troxerutin promoted SirT1-mediated AMP-activated protein kinase (AMPK) activation to inhibit mammalian target of rapamycin complex 1 (mTORC1) signaling, which enhanced nuclear lipin 1 localization, lowered cytoplasmic lipin 1 localization and the ratio of hepatic Lpin 1β/α. Ultimately, troxerutin improved lipid homeostasis by enhancing fatty acid oxidation and triglyceride secretion, and suppressing lipogenesis in HFD-fed mouse livers. In conclusion, troxerutin displayed beneficial effects on hepatic lipid homeostasis in HFD-induced NAFLD by blocking oxidative stress to restore NAD+-depletion-mediated dysfunction of lipin 1 signaling. This study provides novel mechanistic insights into NAFLD pathogenesis and indicates that troxerutin is a candidate for pharmacological intervention of NAFLD via restoring NAD+ levels.

Garlic Essential Oil Protects against Obesity-Triggered Nonalcoholic Fatty Liver Disease through Modulation of Lipid Metabolism and Oxidative Stress

This study investigated the protective properties of garlic essential oil (GEO) and its major organosulfur component (diallyl disulfide, DADS) against the development of nonalcoholic fatty liver disease (NAFLD). C57BL/6J mice were fed a normal or high-fat diet (HFD) with/without GEO (25, 50, and 100 mg/kg) or DADS (10 and 20 mg/kg) for 12 weeks. GEO and DADS dose-dependently exerted antiobesity and antihyperlipidemic effects by reducing HFD-induced body weight gain, adipose tissue weight, and serum biochemical parameters. Administration of 50 and 100 mg/kg GEO and 20 mg/kg DADS significantly decreased the release of pro-inflammatory cytokines in liver, accompanied by elevated antioxidant capacity via inhibition of cytochrome P450 2E1 expression during NAFLD development. The anti-NAFLD effects of GEO and DADS were mediated through down-regulation of sterol regulatory element binding protein-1c, acetyl-CoA carboxylase, fatty acid synthase, and 3-hydroxy-3-methylglutaryl-coenzyme A reductase, as well as stimulation of peroxisome proliferator-activated receptor α and carnitine palmitoyltransferase-1. These results demonstrate that GEO and DADS dose-dependently protected obese mice with long-term HFD-induced NAFLD from lipid accumulation, inflammation, and oxidative damage by ameliorating lipid metabolic disorders and oxidative stress. The dose of 20 mg/kg DADS was equally as effective in preventing NAFLD as 50 mg/kg GEO containing the same amount of DADS, which demonstrates that DADS may be the main bioactive component in GEO.

Gallic acid ameliorated impaired glucose and lipid homeostasis in high fat diet-induced NAFLD mice.

Gallic acid (GA), a naturally abundant plant phenolic compound in vegetables and fruits, has been shown to have potent anti-oxidative and anti-obesity activity. However, the effects of GA on nonalcoholic fatty liver disease (NAFLD) are poorly understood. In this study, we investigated the beneficial effects of GA administration on nutritional hepatosteatosis model by a more “holistic view” approach, namely 1H NMR-based metabolomics, in order to prove efficacy and to obtain information that might lead to a better understanding of the mode of action of GA. Male C57BL/6 mice were placed for 16 weeks on either a normal chow diet, a high fat diet (HFD, 60%), or a high fat diet supplemented with GA (50 and 100 mg/kg/day, orally). Liver histopathology and serum biochemical examinations indicated that the daily administration of GA protects against hepatic steatosis, obesity, hypercholesterolemia, and insulin resistance among the HFD-induced NAFLD mice. In addition, partial least squares discriminant analysis scores plots demonstrated that the cluster of HFD fed mice is clearly separated from the normal group mice plots, indicating that the metabolic characteristics of these two groups are distinctively different. Specifically, the GA-treated mice are located closer to the normal group of mice, indicating that the HFD-induced disturbances to the metabolic profile were partially reversed by GA treatment. Our results show that the hepatoprotective effect of GA occurs in part through a reversing of the HFD caused disturbances to a range of metabolic pathways, including lipid metabolism, glucose metabolism (glycolysis and gluconeogenesis), amino acids metabolism, choline metabolism and gut-microbiota-associated metabolism. Taken together, this study suggested that a 1H NMR-based metabolomics approach is a useful platform for natural product functional evaluation. The selected metabolites are potentially useful as preventive action biomarkers and could also be used to help our further understanding of the effect of GA in hepatosteatosis mice.

L-arginine conjugates of bile acids-a possible treatment for non-alcoholic fatty liver disease.

BackgroundNon-alcoholic fatty liver disease (NAFLD) is a continuum of diseases that include simple steatosis and non-alcoholic steatohepatitis (NASH) ultimately leading to cirrhosis, hepatocellular carcinoma and end stage liver failure. Currently there is no approved treatment for NASH. It is known that bile acids not only have physiological roles in lipid digestion but also have strong hormonal properties. We have synthesized a novel chenodeoxycholyl-arginine ethyl ester conjugate (CDCArg) for the treatment of NAFLD.MethodsChemical synthesis of CDCArg was performed. Experiments for prevention and treatment of NAFLD were carried out on C57BL/6 J male mice that were treated with high fat diet (HFD, 60% calories from fat). CDCArg or cholic acid bile acids were admixture into the diets. Food consumption, weight gain, liver histology, intraperitoneal glucose tolerance test, biochemical analysis and blood parameters were assessed at the end of the experiment after 5 weeks of diet (prevention study) or after 14 weeks of diet (treatment study). In the treatment study CDCArg was admixture into the diet at weeks 10–14.ResultsIn comparison to HFD treated mice, mice treated with HFD supplemented with CDCArg, showed reduced liver steatosis, reduced body weight and decreased testicular fat and liver tissue mass. Blood glucose, cholesterol, insulin and leptin levels were also lower in this group. No evidence of toxicity of CDCArg was recorded. In fact, liver injury, as evaluated using plasma hepatic enzyme levels, was low in mice treated with HFD and CDCArg when compared to mice treated with HFD and cholic acid.ConclusionCDCArg supplementation protected the liver against HFD-induced NAFLD without any toxic effects. These results indicate that basic amino acids e.g., L-arginine and bile acids conjugates may be a potential therapy for NAFLD.