Anti-oxidative effect of apocynin on insulin resistance in high-fat diet mice

The present study examines the effects of apocynin on oxidative stress and antioxidant enzymes in high-fat diet (HFD) induced obese mice. After 12 weeks on HFD, the C57BL/6J mice that clearly exhibited insulin resistance received apocynin (2.4g/L) in their drinking water for five weeks. The results show that apocynin treatment significantly ameliorated hyperglycemia, hyperinsulinemia and dyslipidemia in HFD mice. Furthermore, the intraperitoneal glucose tolerance test (IPGTT) and homeostasis model assessment of insulin resistance (HOMA-IR) indicate significant improvement of insulin sensitivity in HFD mice after apocynin treatment. Compared to the HFD control mice, serum malondialdehyde (MDA) was significantly lower and serum superoxide dismutase (SOD) was significantly higher in apocynin treated HFD mice, indicating that apocynin suppressed systemic oxidative stress in the treated group. In the liver, apocynin significantly reduced the level of MDA. Accordingly, apocynin treatment strengthened the antioxidative defense system with an increased activity of SOD, glutathione-peroxidase (GSHpx) and content of reduced glutathione (GSH). We also found that hepatic catalase (CAT) activity significantly decreased after apocynin treatment which may indicate that apocynin reduces hydrogen peroxide and oxidative stress in the liver. These results suggest that apocynin may ameliorate insulin resistance by reducing systemic and hepatic oxidative stress in HFD fed mice.     

The effect of 1,25-dihydroxyvitamin D3 on liver damage,oxidative stress,and advanced glycation end products in experimental nonalcoholic- and alcoholic- fatty liver disease

Background/aim Oxidative stress and advanced glycation end products (AGEs) formation are proposed as effective mechanisms in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD). 1,25(OH)2D3 was proposed to have antioxidant, antiinflammatory and antiglycation properties. In this study, the effect of 1,25(OH)2D3 treatment on oxidative stress parameters and AGEs levels together with hepatic histopathology was investigated in high fructose (HFr) or ethanol (EtOH)-treated rats. Materials and methods Rats were treated with fructose (30%) or ethanol (5-20%) in drinking water with and without 1,25(OH)2D3 treatment (5 µg/kg two times a week) for 8 weeks. Insulin resistance (IR), oxidative stress parameters, AGEs, triglyceride (TG), and hydroxyproline (Hyp) levels together with histopathology were investigated in the liver. Results1,25(OH)2D3 decreased hepatic reactive oxygen species, lipid and protein oxidation products together with histopathological improvements in HFr- and EtOH-treated rats. 1,25(OH)2D3 treatment was observed to decrease significantly serum and hepatic AGEs in HFr group, and hepatic AGEs in EtOH group.Conclusion Our results clearly show that 1,25(OH)2 D3 treatment may be useful in the alleviation of hepatic lesions by decreasing glycooxidant stress in both NAFLD and ALD models created by HFr- and EtOH-treated rats, respectively.     

Invariant natural killer T cells contribute to chronic-plus-binge ethanol-mediated liver injury by promoting hepatic neutrophil infiltration

Neutrophil infiltration is a hallmark of alcoholic steatohepatitis; however, the underlying mechanisms remain unclear. We previously reported that chronic-plus-binge ethanol feeding synergistically induces hepatic recruitment of neutrophils, which contributes to liver injury. In this paper, we investigated the roles of invariant natural killer T (iNKT) cells in chronic-plus-binge ethanol feeding-induced hepatic neutrophil infiltration and liver injury. Wild-type and two strains of iNKT cell-deficient mice (CD1d- and Jα18-deficient mice) were subjected to chronic-plus-binge ethanol feeding. Liver injury and inflammation were examined. Chronic-plus-binge ethanol feeding synergistically increased the number of hepatic iNKT cells and induced their activation, compared with chronic feeding or binge alone. iNKT cell-deficient mice were protected from chronic-plus-binge ethanol-induced hepatic neutrophil infiltration and liver injury. Moreover, chronic-plus-binge ethanol feeding markedly upregulated the hepatic expression of several genes associated with inflammation and neutrophil recruitment in wild-type mice, but induction of these genes was abrogated in iNKT cell-deficient mice. Importantly, several cytokines and chemokines (e.g., MIP-2, MIP-1, IL-4, IL-6 and osteopontin) involved in neutrophil infiltration were upregulated in hepatic NKT cells isolated from chronic-plus-binge ethanol-fed mice compared to pair-fed mice. Finally, treatment with CD1d blocking antibody, which blocks iNKT cell activation, partially prevented chronic-plus-binge ethanol-induced liver injury and inflammation. Chronic-plus-binge ethanol feeding activates hepatic iNKT cells, which play a critical role in the development of early alcoholic liver injury, in part by releasing mediators that recruit neutrophils to the liver, and thus, iNKT cells represent a potential therapeutic target for the treatment of alcoholic liver disease.     

Effect of Regular Exercise on the Histochemical Changes of d-Galactose-Induced Oxidative Renal Injury in High-Fat Diet-Fed Rats

Renal lipid accumulation exhibits slowly developing chronic kidney disease and is associated with increased oxidative stress. The impact of exercise on the obese- and oxidative stress-related renal disease is not well understood. The purpose of this study was to investigate whether a high-fat diet (HFD) would accelerate d-galactose-induced aging process in rat kidney and to examine the preventive effect of regular exercise on the obese- and oxidative stress-related renal disease. Oxidative stress was induced by an administration of d-galactose (100 mg/kg intraperitoneally injected) for 9 weeks, and d-galactose-treated rats were also fed with a high-fat diet (60% kcal as fat) for 9 weeks to induce obesity. We investigated the efficacy of regular exercise in reducing renal injury by analyzing Nε-carboxymethyllysine (CML), 8-hydroxygluanine (8-OHdG) and apoptosis. When rats were fed with a HFD for 9 weeks in d-galactose-treated rats, an increased CML accumulation, oxidative DNA damage and renal podocyte loss were observed in renal glomerular cells and tubular epithelial cells. However, the regular exercise restored all these renal changes in HFD plus d-galactose-treated rats. Our data suggested that long-term HFD may accelerate the deposition of lipoxidation adducts and oxidative renal injury in d-galactose-treated rats. The regular exercise protects against obese- and oxidative stress-related renal injury by inhibiting this lipoxidation burden.     

Effect of chronic psychosocial stress on nonalcoholic steatohepatitis in mice

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic lipid accumulation which may progress towards inflammation (nonalcoholic steatohepatitis (NASH)). NAFLD is regarded as a consequence of a sedentary, food-abundant lifestyle which, in the modern world, often coincides with chronically high levels of perceived psychosocial stress. Here, we aimed to characterize the effect of chronic psychosocial stress on the development of NAFLD/NASH in male mice either fed with standard chow or NASH-inducing high fat diet. Chronic psychosocial stress was induced by chronic subordinate colony housing (CSC), a pre-clinically validated paradigm relevant for human affective and somatic disorders. Single housed (SHC) mice served as controls. Under standard chow conditions CSC mice revealed lower hepatic triglyceride levels but higher hepatic TNFα, MCP-1 and HMOX mRNA expression, while serum transaminase levels did not significantly differ from SHC mice. Under the NASH-inducing high-fat diet CSC and SHC mice showed similar body weight-gain and serum levels of glucose and adiponectin. Moreover, liver histology as well as TNFα, MCP-1 and HMOX expression were similar in CSC and SHC mice fed with HFD. Surprisingly, CSC showed even significantly lower transaminase levels than SHC mice fed with the same NASH-inducing diet. Together, these data indicate that under normal dietary conditions the CSC model induces noticeable hepatic oxidative stress and inflammation without causing manifest hepatocellular injury. In contrast, CSC exhibited a protective effect on hepatocellular injury in a dietary NASH-model. Identification of the underlying mechanisms of this phenomenon may lead to novel therapeutic strategies to prevent progression of NAFLD.     

抑制NOX缓解酒精肝模型小鼠肝细胞损伤及脂代谢紊乱

背景:研究表明,应激状态下小鼠心肌、骨骼肌、肾脏及脑组织NOX蛋白过度上调,而NOX介导氧化应激在过量饮酒导致的酒精性肝损伤中的作用尚不清楚.目的:探讨NOX介导氧化应激在肝脏正常生理及酒精性肝损伤病理状态下的作用.方法:①6只雄性C57BL/6J小鼠随机分为正常对照组、正常药物组,每组3只;正常药物组腹腔注射NOX抑...     

Higher neutrophil infiltration mediated by osteopontin is a likely contributing factor to the increased susceptibility of females to alcoholic liver disease

Alcoholic liver disease (ALD) is a major public health problem in the United States and women are known to be more susceptible to ALD. However, the precise mechanism for increased susceptibility of females to ALD is not completely understood. The present study is based on the hypothesis that induction of osteopontin (OPN), a matricellular protein, is the likely contributing factor for higher neutrophil recruitment in females during alcoholic steatohepatitis (ASH). ASH was induced in male and female Sprague-Dawley rats by feeding them a Lieber-DeCarli diet containing ethanol (EtOH) for 6 weeks, followed by a single injection of lipopolysaccharide (LPS, 10 mg/kg, ip). Liver injury, measured by plasma transaminase elevations and confirmed by haematoxylin and eosin-stained liver sections, revealed approximately 25-fold higher liver injury in the female ASH model compared with the males. Although steatosis, necrosis, and neutrophil infiltration were evident in both male and female rats, hepatic neutrophilic necrotic foci were noted as early as 2 h after LPS injection in the EtOH-treated female rats. Hepatic neutrophil infiltration correlated with higher expression of cleaved (cOPN) and uncleaved OPN in the EtOH + LPS-treated female rats compared with the males. OPN secretion was localized predominantly in the biliary epithelium and females had significantly higher OPN mRNA than their male counterparts in the ASH model. The ability of OPN to attract neutrophils was further confirmed in vivo, in a peritonitis rat model, and by neutralizing OPN (nOPN) antibody experiments. Hepatic neutrophil infiltration was largely inhibited ( approximately 50%) by nOPN antibody. Flow cytometry experiments revealed OPN-mediated up-regulation of the CD11b neutrophil adhesion molecule. In conclusion, these data suggest that higher hepatic expression of OPN is the likely reason for higher and early hepatic neutrophil infiltration making females more susceptible to ALD during ASH.     

Activation of complement components and reduced regulator expression in alcohol-induced liver injury in the rat

The purpose of this study was to evaluate the possible contribution of complement-mediated inflammation to the development of alcoholic liver disease. Male Wistar rats were fed ethanol by liquid diet in a model that results in continuous ethanol intoxication and induces early signs of alcoholic liver injury. After a six-week study period liver samples were analyzed for the deposition of complement components (C1, C3, and C8) and expression of cell membrane-bound regulators (Crry and CD59). Activation of the homologous complement system in vitro was tested by treating frozen liver sections with normal rat serum (NRS). Immunohistochemical analysis showed deposits of C8 in the liver sections of ethanol-treated rats. When frozen liver sections from these rats were treated with NRS, periportal deposition of both C3 and C8, but only slight C1 deposition, was observed. Immunohistochemical and Western blot analysis both revealed a reduced expression of the complement regulators Crry and CD59. These results suggest an induction of complement-activating capacity in the liver after chronic ethanol treatment. Lack of C1 deposition in the lesions suggests that complement activation occurs primarily via the alternative pathway. The reduced expression of the critical complement regulatory proteins Crry and CD59 may sensitize the liver to complement-mediated damage.     

Regulation of oxidative stress and inflammation by hepatic adiponectin receptor 2 in an animal model of nonalcoholic steatohepatitis

The pathogenesis of nonalcoholic steatohepatitis (NASH) is not well understood; however, the progression of fatty liver to NASH has been linked to oxidative stress and lipid peroxidation in the liver, leading to inflammation. Although the adiponectin receptor 2 (AdipoR2) has been identified as a modulator of oxidative stress and inflammation in the liver, it remains unclear whether the receptor has hepatic antioxidant and anti-inflammatory effects in NASH. In this study, we used an animal model of NASH to examine hepatic AdipoR2. Obese fa/fa Zucker rats fed a high-fat and high-cholesterol (HFC) diet spontaneously developed fatty liver with inflammation and fibrosis, characteristic of NASH, after 4, 8, or 12 weeks of HFC diet consumption. AdipoR2 expression was significantly decreased, whereas the expression of genes related to NADPH oxidase complex were increased. As a result of the decrease in AdipoR2 expression, the mRNA expression of genes located downstream of AdipoR2, i.e., Cu-Zn superoxide dismutase (Cu-Zn SOD) and Mn-SOD, also decreased. Furthermore, the expression of genes related to inflammation was increased. Increased oxidative stress and inflammation by down-regulation of AdipoR2 may contribute to the progression of NASH. Thus, the AdipoR2 might be a crucially important regulator of hepatic oxidative stress and inflammation in NASH.     

Effects of Moderate Alcohol Intake in the Bladder of the Otsuka Long Evans Tokushima Fatty Diabetic Rats

Diabetes is related with a number of cystopathic complications. However, there have been no studies about the influence of alcohol consumption in the bladder of type 2 diabetes. Thus, we investigated the effect of moderate alcohol intake in the bladder of the Otsuka Long Evans Tokushima Fatty (OLETF) diabetic rat. The non-diabetic Long-Evans Tokushima Otsuka (LETO, n=14) and the OLETF control group (n=14) were fed an isocaloric diet; the LETO (n=14) and the OLETF ethanol group (n=14) were fed 36% ethanol 7 g/kg/day. After ten weeks, muscarinic receptors, RhoGEFs, myogenic change, and the level of oxidative stress were evaluated. Moderate alcohol intake significantly decreased excessive muscarinic receptor and Rho kinase expressions in the OLETF rats compared with the LETO rats. In addition, iNOS and collagen expression were not changed in the OLETF rats in spite of alcohol consumption. Superoxide dismutase levels, which is involved in antioxidant defense, in the LETO rats were significantly decreased after alcohol consumption, however those in the OLETF rats were similar. Moderate alcohol consumption reduces the oxidative stress, and may prevent molecular and pathologic changes of the bladder of rats with type 2 diabetes.     

Initiation of alcoholic fatty liver and hepatic inflammation with a specific recall immune response in alcohol-consuming C57Bl/6 mice

Whether immunological responses are involved in initiation and progression of alcoholic liver disease is unclear. We describe a mouse model of alcoholic liver injury characterized by steatosis and hepatic inflammation initiated by a recall immune response. Mice immune to Listeria monocytogenes fed a liquid diet containing ethanol and challenged with viable bacteria developed steatosis within 24 h and, at a later time, elevated serum alanine aminotransferase levels, indicating more liver damage in this group. Listeria antigen also induced steatosis and increased serum alanine aminotransferase levels in immune ethanol-consuming mice. The production of tumour necrosis factor by a recall immune response in this model is a major, but not the only, component in initiation of alcoholic liver disease.     

Experimental rat model for alcohol‐induced osteonecrosis of the femoral head

Alcohol‐induced osteonecrosis of the femoral head (ONFH) is observed in alcohol abusers and patients with alcoholic fatty liver disease. It has been reported that Toll‐like receptor 4 (TLR4) signalling plays a crucial role in the pathogenesis of alcoholic fatty liver disease. We previously reported a corticosteroid‐induced ONFH rat model, and suggested that TLR4 signalling contributes to the pathogenesis of ONFH. Thus, it is thought that the pathogenesis of alcohol‐induced ONFH is probably similar to that of corticosteroid‐induced ONFH. The aim of this study was to develop a new animal model for alcohol‐induced ONFH and to evaluate the relationship between the pro‐inflammatory response via TLRs and the development of ONFH in rats. Male Wistar rats were fed a Lieber–DeCarli liquid diet containing 5% ethanol (experimental group) or dextran (control group) for 1–24 weeks. Histopathological and biochemical analyses were performed. Feeding the ethanol‐containing liquid diet resulted in the development of ONFH with hepatic steatosis, hepatic dysfunction and hyperlipidaemia, whereas feeding the dextran‐containing diet did not cause ONFH. However, we could not recognize any relationship between the pro‐inflammatory response via TLR4 and the development of alcohol‐induced ONFH. Thus in this study we have developed a new rat model for alcohol‐induced ONFH based on the feeding of an ethanol liquid diet. ONFH was observed within seven days from the start of feeding with 5% ethanol‐containing liquid diet. Although this was linked to hepatic steatosis, a TLR4 association was not a feature of this model.     

Role of quercetin in preventing thioacetamide-induced liver injury in rats

In hepatic toxicity induced in rats by two injections of thioacetamide (TAA, 350 mg/kg with an interval of 8 hr), the action of quercetin was investigated. After 96 hr, TAA administration resulted in hepatic necrosis, significant increases in serum transaminase activity, and increases in hepatic lipoperoxidation. Thioacetamide-induced hepatotoxicity also showed changes in antioxidant enzymes in the liver of rats, with alterations in p-ERK 1/2 (phosphorylated extracellular-signal related kinase 1/2) as well as an imbalance between proapototic protein Bax and anti-apoptotic protein Bcl-2 expression. With administration of the flavonoid quercetin (50 mg/Kg i.p.) for four consecutive days following TAA, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity were close to normal values in rats. Histological findings suggested that quercetin had a preventive effect on TAA-induced hepatic necrosis. Quercetin treatment caused significant decreases in lipid peroxide levels in the TAA-treated rats, with some changes in antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Quercetin also inhibited the change of the p-ERK1/2 by TAA and significantly prevented the increase in Bax/Bcl-2 ratio, thus preventing apoptosis. Findings indicate that quercetin may have a preventive effect on TAA-induced hepatotoxicity by modulating the oxidative stress parameters and apoptosis pathway.     

Inflammation,oxidative stress and apoptosis cascade implications in bisphenol A‐induced liver fibrosis in male rats

Bisphenol A (BPA) is a key monomer in the production of plastics. It has been shown to be hepatotoxic. Inflammation and oxidative stress are closely linked with liver fibrosis, the major contributing factor to hepatic failure. Therefore, the aim of this study was to evaluate the impact of chronic exposure to BPA on the development of hepatic fibrosis in male rats and to determine the cross‐talk between the hepatic cytokine network, oxidative stress and apoptosis. For this purpose, 30 male Wistar albino rats were divided into three equal groups as follows: the first group was given no treatment (normal control group); the second group was given corn oil once daily by oral gavage for 8 weeks (vehicle control group); and the third group received BPA (50 mg/kg body weight/day, p.o.) for 8 weeks. BPA administration induced liver fibrosis as reflected in an increase in serum hepatic enzymes activities, hepatic hydroxyproline content and histopathological changes particularly increased collagen fibre deposition around the portal tract. In addition, there was inflammation (as reflected in increase in interleukin‐1beta ‘IL‐1β’, decrease in interleukin‐10 ‘IL‐10′ serum levels and increase in IL‐1β/IL‐10 ratio), oxidative stress (as reflected in increase in malondialdehyde (MDA) level, reduction in reduced glutathione (GSH) content and inhibition of catalase (CAT) activity) and apoptosis [as reflected in an increase in caspase‐3 level and a decrease in numbers of B‐cell lymphoma 2 (BCL2)‐immunopositive hepatocytes]. Interestingly, BPA had an upregulating effect on an extracellular matrix turnover gene [as reflected in matrix metalloproteinase‐9 (MMP‐9)] and a downregulating effect on its inhibitor gene [as reflected in tissue inhibitor of matrix metalloproteinase‐2 (TIMP‐2)] expression. Thus, the mechanism by which BPA induced liver fibrosis seems to be related to stimulation of the inflammatory response, along with oxidative stress, the apoptotic pathway and activation of extracellular matrix turnover.     

Oral low-carbohydrate alcohol liquid diet induces experimental steatohepatitis in the rat

The intragastric tube feeding model of alcoholic liver disease in the rat induces significant liver histopathology, including steatohepatitis and fibrosis. The question is, if the same low-carbohydrate diet is fed ad lib, will the same pathology develop? Rats were fed a liquid diet with ethanol ad lib that was low in calories derived from carbohydrates for 2 months. The urinary ethanol levels (UALs) were monitored at hourly, daily, and weekly intervals, and the growth of the rats was charted. The liver histopathology and blood transaminase levels were determined. Rats fed ethanol grew 1 g/day, which was 2 g/day less than when they were fed the same diet intragastrically. UALs varied hourly between 150 and 500 mg%, daily between 120 and 360 mg%, and weekly between 0 and 500 mg%. Individual rat UALs showed no predictable pattern. The pair-fed controls ate all of their daily ration within 12 h, then fasted until the next day. The histopathology and blood alanine aminotransferase were similar to those seen with the intragastric tube feeding of the same diet, except that necrosis, inflammation, and fibrosis did not develop. The conclusion was that the oral feeding of a low-carbohydrate diet produces less liver injury than that produced by the same diet fed intragastrically. The UALs varied hourly, daily, and weekly in individual rats, making it difficult to synchronize UALs at the time of sacrifice.     

The effect of betaine treatment on triglyceride levels and oxidative stress in the liver of ethanol-treated guinea pigs

We investigated the effect of betaine supplementation on ethanol induced steatosis and alterations in prooxidant and antioxidant status in the liver of guinea pigs. Animals were fed with normal chow or betaine containing chow (2% w/w) for 30 days. Ethanol (3 g/kg, i.p.) was given for the last 10 days. We found that ethanol treatment caused significant increases in plasma transaminase activities, hepatic triglyceride and lipid peroxide levels. Significant decreases in glutathione (GSH), -tocopherol and total ascorbic acid (AA) levels were also observed, but hepatic superoxide dismutase, glutathione peroxidase and glutathione transferase activities remained unchanged as compared with those in controls. Betaine treatment together with ethanol in guinea pigs is found to decrease hepatic triglyceride, lipid peroxide levels and serum transaminase activities and to increase GSH levels. No changes in a-tocopherol and total AA levels and antioxidant enzyme activities were observed with betaine treatment in alcohol treated guinea pigs. In addition, histopathological assessment of guinea pigs showed that betaine reduced the alcoholic fat accumulation in the liver. Based on these data, betaine treatment has a restoring effect on the alterations in triglyceride, lipid peroxide and GSH levels following ethanol ingestion.     

Metallothionein-independent zinc protection from alcoholic liver injury

Previous studies using metallothionein (MT)-overexpressing transgenic mice have demonstrated that MT protects the liver from oxidative injury induced by alcohol. The mechanism of action of MT is unknown. Because MT primarily binds to zinc under physiological conditions and releases zinc under oxidative stress and zinc is an antioxidant element, it is likely that zinc mediates the protective action of MT. The present study was undertaken to determine the distinct role of zinc in hepatic protection from alcoholic injury. MT I/II-knockout (MT-KO) mice along with their wild-type controls were treated with three gastric doses of ethanol at 5 g/kg at 12-hour intervals. Zinc sulfate was injected intraperitoneally in a dosage of 5 mg/kg/day for 3 days before ethanol treatment. MT concentrations in MT-KO mice were very low and zinc concentrations in MT-KO mice were lower than in wild-type mice. Zinc treatment significantly elevated hepatic MT concentrations only in wild-type mice and increased zinc concentrations in both MT-KO and wild-type mice. Ethanol treatment caused degenerative morphological changes and necrotic appearance in the livers of MT-KO mice. Microvesicular steatosis was the only ethanol-induced change in the liver of wild-type mice. Ethanol treatment decreased hepatic glutathione concentrations and increased hepatic lipid peroxidation, and the concentrations of lipid peroxide products in the wild-type mice were lower than in the MT-KO mice. All of these alcohol-induced toxic responses were significantly suppressed by zinc treatment in both MT-KO and wild-type mouse livers. These results demonstrate that zinc, independent of MT, plays an important role in protection from alcoholic liver injury. However, MT is required to maintain high levels of zinc in the liver, suggesting that the protective action of MT in the liver is likely mediated by zinc.     

Carnosine decreased oxidation and glycation products in serum and liver of high‐fat diet and low‐dose streptozotocin‐induced diabetic rats

High‐fat diet (HFD) and low‐dose streptozotocin (STZ)‐treated rats provide useful animal model for type II diabetes mellitus. Oxidative stress and advanced glycation end products (AGEs) play a role in the development of diabetic complications. Carnosine (CAR) has anti‐oxidant and anti‐glycating properties. We investigated the effects of CAR on oxidation and glycation products in HFD+STZ rats. Rats were fed with HFD (60% of total calories from fat) for 4 weeks, and then a single dose of STZ (40 mg/kg; i.p.) was applied. Rats with blood glucose levels above 200 mg/dl were fed with HFD until the end of the 12th week. CAR (250 mg/kg body weight; i.p.; five times a week) was administered to the rats for the last four weeks. CAR significantly decreased serum triglyceride (TG) (57.7%), cholesterol (35.6%) levels and hepatic marker enzyme activities of HFD+STZ rats. It significantly reduced serum reactive oxygen species (ROS) (23.7%), AGEs (13.4%) and advanced oxidized protein products (AOPP) (35.9%) and hepatic TG (59%), ROS (26%), malondialdehyde (MDA) (11.5%), protein carbonyl (PC) (19.2%) and AGE (20.2%) levels. Liver steatosis and hepatocyte ballooning were also significantly reduced. However, CAR treatment did not alter serum glucose and blood glycated haemoglobin and hepatic anti‐oxidant enzyme activities/mRNA expressions in HFD+STZ rats. Our results indicate that CAR decreased accumulation of oxidation and glycation products, such as MDA, AGE, AOPP and PC in the serum and liver and ameliorated hepatic dysfunction in HFD+STZ rats. This effect may be related to its anti‐oxidative, anti‐glycating, and anti‐lipogenic potential.     

A novel cystine based antioxidant attenuates oxidative stress and hepatic steatosis in diet-induced obese mice

Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver pathologies and is associated with obesity and the metabolic syndrome. Here, we investigated the molecular mechanisms by which a novel cystine based glutathione precursor with added selenomethionine (F1) prevents hepatic steatosis in a moderate high fat dietary model of NAFLD. Adult (8 weeks old), male apolipoprotein E (ApoE)−/− mice were fed with a normal diet (ND) or high fat diet (HFD), consisting of 21% fat and 0.21% cholesterol, with or without dietary supplementation of F1 (3 g/kg food) for 16 weeks. Compared with ApoE−/− mice fed with ND with or without F1, ApoE−/− mice fed with HFD exhibited significant weight gain, hepatomegaly, and increased serum cholesterol and triglycerides levels with no change in serum albumin levels. High resolution light and electron microscopy revealed micro-and macro-vesicular steatosis in ApoE−/− mice fed on a HFD. HFD-induced obesity also led to increased lipogenesis, oxidative stress, activation of c-Jun-NH₂-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), perturbation of the BAX/BCL-2 rheostat, hepatocyte apoptosis, and activation of caspases 9 and 3. F1 fully prevented the adverse effects of HFD on serum triglyceride levels, body and liver weights, and hepatic steatosis and substantially attenuated HFD-induced increase in lipogenesis, oxidative stress, kinase activation, apoptotic signaling, and hepatocyte ultrastructural abnormalities. These results demonstrate that administration of F1, a glutathione precursor, ameliorates HFD-induced hepatic steatosis in ApoE−/− mice and emphasizes the role of oxidative stress in diet-induced obesity and hepatic steatosis.