scholarly journals Dietary Glycotoxins Impair Hepatic Lipidemic Profile in Diet-Induced Obese Rats Causing Hepatic Oxidative Stress and Insulin Resistance

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
C. Neves ◽  
T. Rodrigues ◽  
J. Sereno ◽  
C. Simões ◽  
J. Castelhano ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Fatty Acid ◽  
High Fat Diet ◽  
De Novo ◽  
Liver Lipid ◽  
Lipid Fraction ◽  
De Novo Lipogenesis ◽  
High Fat ◽  
Obese Rats

Nonalcoholic fatty liver disease (NAFLD) is caused by excessive liver lipid accumulation, but insulin resistance is specifically associated with impaired lipid saturation, oxidation, and storage (esterification), besides increased de novo lipogenesis. We hypothesized that dietary glycotoxins could impair hepatic lipid metabolism in obesity contributing to lipotoxicity-driven insulin resistance and thus to the onset of nonalcoholic steatohepatitis (NASH). In diet-induced obese rats with methylglyoxal-induced glycation, magnetic resonance spectroscopy, mass spectrometry, and gas chromatography were used to assess liver composition in fatty acyl chains and phospholipids. High-fat diet-induced obesity increased liver lipid fraction and suppressed de novo lipogenesis but did not change fatty acid esterification and saturation or insulin sensitivity. Despite a similar increase in total lipid fraction when supplementing the high-fat diet with dietary glycotoxins, impairment in the suppression of de novo lipogenesis and decreased fatty acid unsaturation and esterification were observed. Moreover, glycotoxins also decreased polyunsaturated cardiolipins and caused oxidative stress, portal inflammation, and insulin resistance in high-fat diet-induced obese rats. Dietary glycated products do not change total lipid levels in the liver of obese rats but dramatically modify the lipidemic profile, leading to oxidative stress, hepatic lipotoxicity, and insulin resistance in obesity and thus contribute to the onset of NASH.

scholarly journals PO-193 Exercise training decreased lipid accumulation in murine skeletal muscle through Sestrin2-mediated SHIP2-JNK signaling pathway

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Tianyi Wang ◽  
Song Huang ◽  
Xiao Han ◽  
Sujuan Liu ◽  
Yanmei Niu ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Fatty Acid ◽  
Lipid Metabolism ◽  
Exercise Training ◽  
High Fat Diet ◽  
De Novo ◽  
Underlying Mechanism ◽  
Wild Type ◽  
High Fat

Objective Obesity is becoming increasingly prevalent and is an important contributor to the worldwide burden of diseases. It is widely accepted that exercise training is beneficial for the prevention and treatment of obesity. However, the underlying mechanism by which exercise training improving skeletal muscle lipid metabolism is still not fully described. Sestrins (Sestrin1-3) are highly conserved stress-inducible protein. Concomitant ablation of Sestrin2 and Sestrin3 has been reported to provoke hepatic mTORC1/S6K1 activation and insulin resistance even without nutritional overload and obesity, implicating that Sestrin2 and Sestrin3 have an important homeostatic function in the control of mammalian glucose and lipid metabolism. Our previous results demonstrated that physical exercise increased Sestrin2 expression in murine skeletal muscle, while the role of Sestrin2 in regulating lipid metabolism remains unknown.  SH2 domain containing inositol 5-phosphatase (SHIP2) acts as a negative regulator of the insulin signaling both in vitro and in vivo. An increased expression of SHIP2 inhibits the insulin-induced Akt activation, glucose uptake, and glycogen synthesis in 3T3-L1 adipocytes, L6 myotubes and tissues of animal models. Alterations of SHIP2 expression and/or enzymatic function appear to have a profound impact on the development of insulin resistance. However, the regulatory function of SHIP2 in lipid metabolism after exercise remains unclear. It has been reported that SHIP2 modulated lipid metabolism through regulating the activity of c-Jun N-terminal kinase (JNK) and Sterol regulatory element-binding protein-1 (SREBP-1). JNK is a subclass of mitogen-activated protein kinase (MAPK) signaling pathway in mammalian cells and plays a crucial role in metabolic changes and inflammation associated with a high-fat diet. Inhibition of JNK reduces lipid deposition and proteins level of fatty acid de novo synthesis in liver cells. It has been reported that Sestrin2 regulated the phosphorylation of JNK, however the underlying mechanism remains unclear. SREBP-1 is important in regulating cholesterol biosynthesis and uptake and fatty acid biosynthesis, and SREBP-1 expression produces two different isoforms, SREBP-1a and SREBP-1c. SREBP-1c is responsible for regulating the genes required for de novo lipogenesis and its expression is regulated by insulin. SREBP-1a regulates genes related to lipid and cholesterol production and its activity is regulated by sterol levels in the cell. Altogether, the purpose of this study was to explore the effect and underlying mechanism of Sestrin2 on lipid accumulation after exercise training. Methods Male wild type and SESN2−/− mice were divided into normal chow (NC) and high-fat diet (HFD) groups to create insulin resistance mice model. After 8 weeks the IR model group was then divided into HFD sedentary control and HFD exercise groups (HE). Mice in HE group underwent 6-week treadmill exercise to reveal the effect of exercise training on lipid metabolism in insulin resistance model induced by HFD. We explored the mechanism through which Sestrin2 regulated lipid metabolism in vitro by supplying palmitate, overexpressing or inhibiting SESNs, SHIP2 and JNK in myotubes. Results We found that 6-week exercise training decreased body weight, BMI and fat mass in wild type and SESN2-/- mice after high-fat diet (HFD) feeding. And exercise training decreased the level of plasma glucose, serum insulin, triglycerides and free fatty acids in wild type but not in Sestrin2-/- mice. Lipid droplet in skeletal muscle was also decreased in wild type but did not in Sestrin2-/- mice. Moreover, exercise training increased the proteins expression involved in fatty acid oxidation and decreased the proteins which related to fatty acid de novo synthesis. The results of oil red staining and the change of proteins related to fatty acid de novo synthesis and beta oxidation in myotubes treated with palmitate, Ad-SESN2 and siRNA-Sestrin2 were consisted with the results in vivo, which suggested that Sestrin2 was a key regulator in lipid metabolism. Exercise training increased Sestrin2 expression and reversed up-regulation of SHIP2 and pJNK induced by HFD in wild type mice but not in Sestrin2-/- mice. In parallel, overexpression of Sestrin2 decreased the level of SHIP2 and pJNK induced by palmitate while Sestrin2 knock down by siRNA-Sestrin2 treatment did not change the expression of SHIP2 and pJNK, which suggested that Sestrin2 modulated SHIP2 and JNK in the state of abnormal lipid metabolism. Inhibition of SHIP2 reduced the activity of JNK, increased lipid accumulation and the proteins of fatty acid synthesis after palmitate treatment and over expression of Sestrin2, which suggest that Sestrin2 modulated lipid metabolism through SHIP2/JNK pathway. Conclusions Sestrin2 plays an important role in improving lipid metabolism after exercise training, and Sestrin2 regulates lipid metabolism by SHIP2-JNK pathway in skeletal muscle.

scholarly journals Protective role of melatonin against adipose-hepatic metabolic comorbidities in experimentally induced obese rat model

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260546
Author(s):  
Mary J. Obayemi ◽  
Christopher O. Akintayo ◽  
Adesola A. Oniyide ◽  
Ayodeji Aturamu ◽  
Olabimpe C. Badejogbin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Food Intake ◽  
High Fat Diet ◽  
Wistar Rats ◽  
Liver Lipid ◽  
Control Group ◽  
Metabolic Dysfunction ◽  
High Fat ◽  
Male Wistar Rats

Background Adipose and hepatic metabolic dysfunctions are critical comorbidities that also aggravate insulin resistance in obese individuals. Melatonin is a low-cost agent and previous studies suggest that its use may promote metabolic health. However, its effects on some comorbidities associated with obesity are unknown. Herein, we investigated the hypothesis that melatonin supplementation would attenuate adipose-hepatic metabolic dysfunction in high fat diet (HFD)-induced obesity in male Wistar rats. Materials and methods Twenty-four adult male Wistar rats (n = 6/group) were used: Control group received vehicle (normal saline), obese group received 40% high fat diet, melatonin-treated group received 4 mg/kg of melatonin, and obese plus melatonin group received 40% HFD and melatonin. The treatment lasted for 12 weeks. Results HFD caused increased food intake, body weight, insulin level, insulin resistance and plasma and liver lipid but decreased adipose lipid. In addition, HFD also increased plasma, adipose and liver malondialdehyde, IL-6, uric acid and decreased Glucose-6-phosphate dehydrogenase, glutathione, nitric oxide and circulating obestatin concentration. However, these deleterious effects except food intake were attenuated when supplemented with melatonin. Conclusion Taken together, the present results indicate that HFD exposure causes adipose-hepatic metabolic disturbance in obese animals, which are accompanied by oxidative stress and inflammation. In addition, the present results suggest that melatonin supplementation attenuates adipose-hepatic metabolic dysfunction, accompanying obesity by suppression of oxidative stress/inflammation-dependent mechanism and increasing circulating obestatin.

Loss of regulation of lipogenesis in the Zucker diabetic rat. II. Changes in stearate and oleate synthesis

2002 ◽  
Vol 282 (3) ◽  
pp. E507-E513 ◽  
Author(s):  
Sara Bassilian ◽  
Syed Ahmed ◽  
Shu K. Lim ◽  
Laszlo G. Boros ◽  
Catherine S. Mao ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Dietary Fat ◽  
High Fat Diet ◽  
Fatty Acid Synthase ◽  
De Novo ◽  
De Novo Lipogenesis ◽  
Chain Elongation ◽  
High Fat ◽  
Zdf Rat

De novo lipogenesis and dietary fat uptake are two major sources of fatty acid deposits in fat of obese animals. To determine the relative contribution of fatty acids from these two sources in obesity, we have determined the distribution of c16 and c18 fatty acids of triglycerides in plasma, liver, and epididymal fat pad of Zucker diabetic fatty (ZDF) rats and their lean littermates (ZL) under two isocaloric dietary fat conditions. Lipogenesis was also determined using the deuterated water method. Conversion of palmitate to stearate and stearate to oleate was calculated from the deuterium incorporation by use of the tracer dilution principle. In the ZL rat, lipogenesis was suppressed from 70 to 24%, conversion of palmitate to stearate from 86 to 78%, and conversion of stearate to oleate from 56 to 7% in response to an increase in the dietary fat-to-carbohydrate ratio. The results suggest that suppression of fatty acid synthase and stearoyl-CoA desaturase activities is a normal adaptive mechanism to a high-fat diet. In contrast, de novo lipogenesis, chain elongation, and desaturation were not suppressed by dietary fat in the ZDF rat. The lack of ability to adapt to a high-fat diet resulted in a higher plasma triglyceride concentration and excessive fat accumulation from both diet and de novo synthesis in the ZDF rat.

scholarly journals miR-146a regulates insulin sensitivity via NPR3

2020 ◽  
Author(s):  
Julian Roos ◽  
Meike Dahlhaus ◽  
Jan-Bernd Funcke ◽  
Monika Kustermann ◽  
Gudrun Strauss ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Glucose Uptake ◽  
High Fat Diet ◽  
Metabolic Diseases ◽  
De Novo ◽  
Liver Steatosis ◽  
De Novo Lipogenesis ◽  
Loss Of Function ◽  
High Fat

AbstractThe pathogenesis of obesity-related metabolic diseases has been linked to the inflammation of white adipose tissue (WAT), but the molecular interconnections are still not fully understood. MiR-146a controls inflammatory processes by suppressing pro-inflammatory signaling pathways. The aim of this study was to characterize the role of miR-146a in obesity and insulin resistance. MiR-146a−/− mice were subjected to a high-fat diet followed by metabolic tests and WAT transcriptomics. Gain- and loss-of-function studies were performed using human Simpson–Golabi–Behmel syndrome (SGBS) adipocytes. Compared to controls, miR-146a−/− mice gained significantly more body weight on a high-fat diet with increased fat mass and adipocyte hypertrophy. This was accompanied by exacerbated liver steatosis, insulin resistance, and glucose intolerance. Likewise, adipocytes transfected with an inhibitor of miR-146a displayed a decrease in insulin-stimulated glucose uptake, while transfecting miR-146a mimics caused the opposite effect. Natriuretic peptide receptor 3 (NPR3) was identified as a direct target gene of miR-146a in adipocytes and CRISPR/Cas9-mediated knockout of NPR3 increased insulin-stimulated glucose uptake and enhanced de novo lipogenesis. In summary, miR-146a regulates systemic and adipocyte insulin sensitivity via downregulation of NPR3.

scholarly journals Anthocyanins from black wolfberry (Lycium ruthenicum Murr.) prevent inflammation and increase fecal fatty acid in diet-induced obese rats

RSC Advances ◽  
2017 ◽  
Vol 7 (75) ◽  
pp. 47848-47853 ◽  
Author(s):  
Jinjin Yin ◽  
Tao Wu
Keyword(s):  
Oxidative Stress ◽  
Fatty Acid ◽  
High Fat Diet ◽  
Sprague Dawley ◽  
High Fat ◽  
Sprague Dawley Rats ◽  
Lycium Ruthenicum ◽  
Obese Rats ◽  
Lycium Ruthenicum Murr ◽  
Obese Male

This study aimed to determine whether black wolfberry (Lycium ruthenicumMurr.) anthocyanin (BWA) consumption can alleviate oxidative stress and reduce inflammation in high-fat diet-induced obese male Sprague-Dawley rats.

scholarly journals Amelioration of Hepatic Steatosis in Mice through Bacteroides uniformis CBA7346-Mediated Regulation of High-Fat Diet-Induced Insulin Resistance and Lipogenesis

Nutrients ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 2989
Author(s):  
Hye-Bin Lee ◽  
Moon-Ho Do ◽  
Hyunjhung Jhun ◽  
Sang-Keun Ha ◽  
Hye-Seon Song ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Liver Disease ◽  
Fatty Liver ◽  
High Fat Diet ◽  
Fatty Liver Disease ◽  
De Novo ◽  
De Novo Lipogenesis ◽  
Model Assessment ◽  
High Fat ◽  
Alcoholic Fatty Liver

Dietary habits and gut microbiota play an essential role in non-alcoholic fatty liver disease (NAFLD) and related factors such as insulin resistance and de novo lipogenesis. In this study, we investigated the protective effects of Bacteroides uniformis CBA7346, isolated from the gut of healthy Koreans, on mice with high-fat diet (HFD)-induced NAFLD. Administration of B. uniformis CBA7346 reduced body and liver weight gain, serum alanine aminotransferase and aspartate aminotransferase levels, liver steatosis, and liver triglyceride levels in mice on an HFD; the strain also decreased homeostatic model assessment for insulin resistance values, as well as serum cholesterol, triglyceride, lipopolysaccharide, leptin, and adiponectin levels in mice on an HFD. Moreover, B. uniformis CBA7346 controlled fatty liver disease by attenuating steatosis and inflammation and regulating de novo lipogenesis-related proteins in mice on an HFD. Taken together, these findings suggest that B. uniformis CBA7346 ameliorates HFD-induced NAFLD by reducing insulin resistance and regulating de novo lipogenesis in obese mice.

scholarly journals Shrimp oil extracted from the shrimp processing waste reduces the development of insulin resistance and metabolic phenotypes in diet-induced obese rats

2017 ◽  
Vol 42 (8) ◽  
pp. 841-849 ◽  
Author(s):  
Sandhya Nair ◽  
Jacques Gagnon ◽  
Claude Pelletier ◽  
Nadia Tchoukanova ◽  
Junzeng Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Glucose Tolerance ◽  
Chronic Inflammation ◽  
High Fat Diet ◽  
High Fat ◽  
Low Fat ◽  
Low Fat Diet ◽  
Obese Rats ◽  
Shrimp Oil

Diet-induced obesity, insulin resistance, impaired glucose tolerance, chronic inflammation, and oxidative stress represent the main features of type 2 diabetes mellitus. The present study was conducted to examine the efficacy and mechanisms of shrimp oil on glucose homeostasis in obese rats. Male CD rats fed a high-fat diet (52 kcal% fat) and 20% fructose drinking water were divided into 4 groups and treated with the dietary replacement of 0%, 10%, 15%, or 20% of lard with shrimp oil for 10 weeks. Age-matched rats fed a low-fat diet (10 kcal% fat) were used as the normal control. Rats on the high-fat diet showed impaired (p < 0.05) glucose tolerance and insulin resistance compared with rats fed the low-fat diet. Shrimp oil improved (p < 0.05) oral glucose tolerance, insulin response, and homeostatic model assessment-estimated insulin resistance index; decreased serum insulin, leptin, hemoglobin A1c, and free fatty acids; and increased adiponectin. Shrimp oil also increased (p < 0.05) antioxidant capacity and reduced oxidative stress and chronic inflammation. The results demonstrated that shrimp oil dose-dependently improved glycemic control in obese rats through multiple mechanisms.

scholarly journals Neurodegeneration in an animal model of Parkinson's disease is exacerbated by a high-fat diet

2010 ◽  
Vol 299 (4) ◽  
pp. R1082-R1090 ◽  
Author(s):  
Jill K. Morris ◽  
Gregory L. Bomhoff ◽  
John A. Stanford ◽  
Paige C. Geiger
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Animal Model ◽  
Locomotor Activity ◽  
Substantia Nigra ◽  
High Fat Diet ◽  
Model Assessment ◽  
High Fat

Despite numerous clinical studies supporting a link between type 2 diabetes (T2D) and Parkinson's disease (PD), the clinical literature remains equivocal. We, therefore, sought to address the relationship between insulin resistance and nigrostriatal dopamine (DA) in a preclinical animal model. High-fat feeding in rodents is an established model of insulin resistance, characterized by increased adiposity, systemic oxidative stress, and hyperglycemia. We subjected rats to a normal chow or high-fat diet for 5 wk before infusing 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. Our goal was to determine whether a high-fat diet and the resulting peripheral insulin resistance would exacerbate 6-OHDA-induced nigrostriatal DA depletion. Prior to 6-OHDA infusion, animals on the high-fat diet exhibited greater body weight, increased adiposity, and impaired glucose tolerance. Two weeks after 6-OHDA, locomotor activity was tested, and brain and muscle tissue was harvested. Locomotor activity did not differ between the groups nor did cholesterol levels or measures of muscle atrophy. High-fat-fed animals exhibited higher homeostatic model assessment of insulin resistance (HOMA-IR) values and attenuated insulin-stimulated glucose uptake in fast-twitch muscle, indicating decreased insulin sensitivity. Animals in the high-fat group also exhibited greater DA depletion in the substantia nigra and the striatum, which correlated with HOMA-IR and adiposity. Decreased phosphorylation of HSP27 and degradation of IκBα in the substantia nigra indicate increased tissue oxidative stress. These findings support the hypothesis that a diet high in fat and the resulting insulin resistance may lower the threshold for developing PD, at least following DA-specific toxin exposure.

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