scholarly journals Defining high-fat-diet rat models: metabolic and molecular effects of different fat types

2006 ◽  
Vol 36 (3) ◽  
pp. 485-501 ◽  
Author(s):  
R Buettner ◽  
K G Parhofer ◽  
M Woenckhaus ◽  
C E Wrede ◽  
L A Kunz-Schughart ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Fatty Acid ◽  
Olive Oil ◽  
Hepatic Steatosis ◽  
Expression Profiles ◽  
Whole Body ◽  
High Fat ◽  
Plasma Parameters ◽  
Insulin Effect ◽  
Molecular Effects

High-fat (HF)-diet rodent models have contributed significantly to the analysis of the pathophysiology of the insulin resistance syndrome, but their phenotype varies distinctly between different studies. Here, we have systematically compared the metabolic and molecular effects of different HF with varying fatty acid compositions. Male Wistar rats were fed HF diets (42% energy; fat sources: HF-L – lard; HF-O – olive oil; HF-C – coconut fat; HF-F – fish oil). Weight, food intake, whole-body insulin tolerance and plasma parameters of glucose and lipid metabolism were measured during a 12-week diet course. Liver histologies and hepatic gene expression profiles, using Affymetrix GeneChips, were obtained. HF-L and HF-O fed rats showed the most pronounced obesity and insulin resistance; insulin sensitivity in HF-C and HF-F was close to normal. Plasma ω-3 polyunsaturated fatty acid (ω-3-PUFA) and saturated fatty acid (C12-C14, SFA) levels were elevated in HF-F and HF-C animals respectively. The liver histologies showed hepatic steatosis in HF-L, HF-O and HF-C without major inflammation. Hepatic SREBP1c-dependent genes were upregulated in these diets, whereas PPARα-dependent genes were predominantly upregulated in HF-F fed rats. We detected classical HF effects only in diets based on lard and olive oil (mainly long-chain, saturated (LC-SFA) and monounsaturated fatty acids (MUFA)). PUFA- or MC-SFA-rich diets did not induce insulin resistance. Diets based on LC-SFA and MUFA induced hepatic steatosis with SREBP1c activation. This points to an intact transcriptional hepatic insulin effect despite resistance to insulin’s metabolic actions.

scholarly journals Peroxisome Proliferator-Activated Receptor (PPAR) Activation Induces Tissue-Specific Effects on Fatty Acid Uptake and Metabolism in Vivo—A Study Using the Novel PPARα/γ Agonist Tesaglitazar

Endocrinology ◽  
2004 ◽  
Vol 145 (7) ◽  
pp. 3158-3164 ◽  
Author(s):  
Bronwyn D. Hegarty ◽  
Stuart M. Furler ◽  
Nicholas D. Oakes ◽  
Edward W. Kraegen ◽  
Gregory J. Cooney
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Fatty Acid ◽  
Insulin Sensitivity ◽  
Insulin Action ◽  
Whole Body ◽  
Peroxisome Proliferator ◽  
The Novel ◽  
High Fat

Abstract Agonists of peroxisome proliferator-activated receptors (PPARs) have emerged as important pharmacological agents for improving insulin action. A major mechanism of action of PPAR agonists is thought to involve the alteration of the tissue distribution of nonesterified fatty acid (NEFA) uptake and utilization. To test this hypothesis directly, we examined the effect of the novel PPARα/γ agonist tesaglitazar on whole-body insulin sensitivity and NEFA clearance into epididymal white adipose tissue (WAT), red gastrocnemius muscle, and liver in rats with dietary-induced insulin resistance. Wistar rats were fed a high-fat diet (59% of calories as fat) for 3 wk with or without treatment with tesaglitazar (1 μmol·kg−1·d−1, 7 d). NEFA clearance was measured using the partially metabolizable NEFA tracer, 3H-R-bromopalmitate, administered under conditions of basal or elevated NEFA availability. Tesaglitazar improved the insulin sensitivity of high-fat-fed rats, indicated by an increase in the glucose infusion rate during hyperinsulinemic-euglycemic clamp (P < 0.01). This improvement in insulin action was associated with decreased diglyceride (P < 0.05) and long chain acyl coenzyme A (P < 0.05) in skeletal muscle. NEFA clearance into WAT of high-fat-fed rats was increased 52% by tesaglitazar under basal conditions (P < 0.001). In addition the PPARα/γ agonist moderately increased hepatic and muscle NEFA utilization and reduced hepatic triglyceride accumulation (P < 0.05). This study shows that tesaglitazar is an effective insulin-sensitizing agent in a mild dietary model of insulin resistance. Furthermore, we provide the first direct in vivo evidence that an agonist of both PPARα and PPARγ increases the ability of WAT, liver, and skeletal muscle to use fatty acids in association with its beneficial effects on insulin action in this model.

scholarly journals Deepure Tea Improves High Fat Diet-Induced Insulin Resistance and Nonalcoholic Fatty Liver Disease

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jing-Na Deng ◽  
Juan Li ◽  
Hong-Na Mu ◽  
Yu-Ying Liu ◽  
Ming-Xia Wang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Fatty Acid ◽  
Hepatic Steatosis ◽  
Fatty Acid Synthesis ◽  
High Fat Diet ◽  
Molecular Mechanisms ◽  
Regulatory Element ◽  
Acid Synthesis ◽  
High Fat ◽  
The Metabolic Syndrome

This study was to explore the protective effects of Deepure tea against insulin resistance and hepatic steatosis and elucidate the potential underlying molecular mechanisms. C57BL/6 mice were fed with a high fat diet (HFD) for 8 weeks to induce the metabolic syndrome. In the Deepure tea group, HFD mice were administrated with Deepure tea at 160 mg/kg/day by gavage for 14 days. The mice in HFD group received water in the same way over the same period. The age-matched C57BL/6 mice fed with standard chow were used as normal control. Compared to the mice in HFD group, mice that received Deepure tea showed significantly reduced plasma insulin and improved insulin sensitivity. Deepure tea increased the expression of insulin receptor substrate 2 (IRS-2), which plays an important role in hepatic insulin signaling pathway. Deepure tea also led to a decrease in hepatic fatty acid synthesis and lipid accumulation, which were mediated by the downregulation of sterol regulatory element binding protein 1c (SREBP-1c), fatty acid synthesis (FAS), and acetyl-CoA carboxylase (ACC) proteins that are involved in liver lipogenesis. These results suggest that Deepure tea may be effective for protecting against insulin resistance and hepatic steatosis via modulating IRS-2 and downstream signaling SREBP-1c, FAS, and ACC.

Combined effects of rosiglitazone and conjugated linoleic acid on adiposity, insulin sensitivity, and hepatic steatosis in high-fat-fed mice

2007 ◽  
Vol 292 (6) ◽  
pp. G1671-G1682 ◽  
Author(s):  
Li-Fen Liu ◽  
Aparna Purushotham ◽  
Angela A. Wendel ◽  
Martha A. Belury
Keyword(s):  
Insulin Resistance ◽  
Fatty Acid ◽  
Weight Gain ◽  
Insulin Sensitivity ◽  
Hepatic Steatosis ◽  
Mrna Levels ◽  
Combined Effects ◽  
High Fat ◽  
Tnf Α ◽  
Adipose Mass

Dysfunctional cross talk between adipose tissue and liver tissue results in metabolic and inflammatory disorders. As an insulin sensitizer, rosiglitazone (Rosi) improves insulin resistance yet causes increased adipose mass and weight gain in mice and humans. Conjugated linoleic acid (CLA) reduces adipose mass and body weight gain but induces hepatic steatosis in mice. We examined the combined effects of Rosi and CLA on adiposity, insulin sensitivity, and hepatic steatosis in high-fat-fed male C57Bl/6 mice. CLA alone suppressed weight gain and adipose mass but caused hepatic steatosis. Addition of Rosi attenuated CLA-induced insulin resistance and dysregulation of adipocytokines. In adipose, CLA significantly suppressed lipoprotein lipase and fatty acid translocase (FAT/CD36) mRNA, suggesting inhibition of fatty acid uptake into adipose; addition of Rosi completely rescued this effect. In addition, CLA alone increased markers of macrophage infiltration, F4/80, and CD68 mRNA levels, without inducing TNF-α in epididymal adipose tissue. The ratio of Bax to Bcl2, a marker of apoptosis, was significantly increased in adipose of the CLA-alone group and was partially prevented by treatment of Rosi. Immunohistochemistry of F4/80 demonstrates a proinflammatory response induced by CLA in epididymal adipose. In the liver, CLA alone induced microsteatotic liver but surprisingly increased the rate of very-low-density lipoprotein-triglyceride production without inducing inflammatory mediator-TNF-α and markers of macrophage infiltration. These changes were accompanied by significantly increased mRNA levels of stearoyl-CoA desaturase, FAT/CD36, and fatty acid synthase. The combined administration of CLA and Rosi reduced hepatic liver triglyceride content as well as lipogenic gene expression compared with CLA alone. In summary, dietary CLA prevented weight gain in Rosi-treated mice without attenuating the beneficial effects of Rosi on insulin sensitivity. Rosi ameliorated CLA-induced lipodystrophic disorders that occurred in parallel with rescued expression of adipocytokine and adipocytes-abundant genes.

scholarly journals P2Y2R Deficiency Ameliorates Hepatic Steatosis by Reducing Lipogenesis and Enhancing Fatty Acid β-Oxidation through AMPK and PGC-1α Induction in High-Fat Diet-Fed Mice

2021 ◽  
Vol 22 (11) ◽  
pp. 5528
Author(s):  
Theodomir Dusabimana ◽  
Eun Jung Park ◽  
Jihyun Je ◽  
Kyuho Jeong ◽  
Seung Pil Yun ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Fatty Acid ◽  
Liver Disease ◽  
Hepatic Steatosis ◽  
High Fat Diet ◽  
Purinergic Receptor ◽  
Lipolytic Enzyme ◽  
High Fat ◽  
Alcoholic Fatty Liver ◽  
Mitochondrial Fatty Acid

Non-alcoholic fatty liver disease (NAFLD) is a chronic metabolic liver disease associated with obesity and insulin resistance. Activation of the purinergic receptor P2Y2R has been reported to promote adipogenesis, inflammation and dyslipidemia in adipose tissues in obese mice. However, the role of P2Y2R and its mechanisms in NAFLD remain unknown. We hypothesized that P2Y2R deficiency may play a protective role in NAFLD by modulating lipid metabolism in the liver. In this study, we fed wild type and P2Y2R knockout mice with a high-fat diet (HFD) for 12 weeks and analyzed metabolic phenotypes. First, P2Y2R deficiency effectively improved insulin resistance with a reduction in body weight and plasma insulin. Second, P2Y2R deficiency attenuated hepatic lipid accumulation and injury with reduced alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Third, P2Y2R deficiency decreased the expression of fatty acid synthesis mediators (cluster of differentiation (CD36), fatty acid synthase (FAS), and stearoyl-CoA desaturase 1 (SCD1)); and increased the expression of adipose triglyceride lipase (ATGL), a lipolytic enzyme. Mechanistically, P2Y2R deficiency increased the AMP-activated protein kinase (AMPK) activity to improve mitochondrial fatty acid β-oxidation (FAO) by regulating acetyl-CoA carboxylase (ACC) and carnitine palmitoyltransferase 1A (CPT1A)-mediated FAO pathway. In addition, P2Y2R deficiency increased peroxisome proliferator-activated gamma co-activator-1α (PGC-1α)-mediated mitochondrial biogenesis. Conclusively, P2Y2R deficiency ameliorated HFD-induced hepatic steatosis by enhancing FAO through AMPK signaling and PGC-1α pathway, suggesting P2Y2R as a promising therapeutic target for NAFLD.

scholarly journals Prenatal and Postnatal Pathways to Obesity: Different Underlying Mechanisms, Different Metabolic Outcomes

Endocrinology ◽  
2007 ◽  
Vol 148 (5) ◽  
pp. 2345-2354 ◽  
Author(s):  
Nichola M. Thompson ◽  
Amy M. Norman ◽  
Shawn S. Donkin ◽  
Ravi R. Shankar ◽  
Mark H. Vickers ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Fatty Acid ◽  
Insulin Sensitivity ◽  
Metabolic Regulation ◽  
Fatty Acid Synthase ◽  
Whole Body ◽  
High Fat ◽  
Metabolic Outcomes ◽  
Underlying Mechanisms ◽  
Pkc Ζ

Obesity and type 2 diabetes are worldwide health issues. The present paper investigates prenatal and postnatal pathways to obesity, identifying different metabolic outcomes with different effects on insulin sensitivity and different underlying mechanisms involving key components of insulin receptor signaling pathways. Pregnant Wistar rats either were fed chow ad libitum or were undernourished throughout pregnancy, generating either control or intrauterine growth restricted (IUGR) offspring. Male offspring were fed either standard chow or a high-fat diet from weaning. At 260 d of age, whole-body insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp, and other metabolic parameters were measured. As expected, high-fat feeding caused diet-induced obesity (DIO) and insulin resistance. Importantly, the insulin sensitivity of IUGR offspring was similar to that of control offspring, despite fasting insulin hypersecretion and increased adiposity, irrespective of postnatal nutrition. Real-time PCR and Western blot analyses of key markers of insulin sensitivity and metabolic regulation showed that IUGR offspring had increased hepatic levels of atypical protein kinase C ζ (PKC ζ) and increased expression of fatty acid synthase mRNA. In contrast, DIO led to decreased expression of fatty acid synthase mRNA and hepatic steatosis. The decrease in hepatic PKC ζ with DIO may explain, at least in part, the insulin resistance. Our data suggest that the mechanisms of obesity induced by prenatal events are fundamentally different from those of obesity induced by postnatal high-fat nutrition. The origin of insulin hypersecretion in IUGR offspring may be independent of the mechanistic events that trigger the insulin resistance commonly observed in DIO.

scholarly journals Myocardial Lipid Profiling During Time Course of High Fat Diet and its Relationship to the Expression of Fatty Acid Transporters

2015 ◽  
Vol 37 (3) ◽  
pp. 1147-1158 ◽  
Author(s):  
Ewa Harasim ◽  
Tomasz Stępek ◽  
Karolina Konstantynowicz-Nowicka ◽  
Marcin Baranowski ◽  
Jan Górski ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Liquid Chromatography ◽  
Fatty Acid ◽  
Lipid Profile ◽  
High Fat Diet ◽  
Time Course ◽  
Whole Body ◽  
Gas Liquid Chromatography ◽  
High Fat ◽  
Lipid Fractions

Background/Aims: It is well documented that increased fatty acids (FA) supply causes lipid accumulation and insulin resistance in skeletal muscles. Whether the same mechanism is present in the heart is still unclear. Therefore, the goal of our study was to determine the content of specific myocardial lipid fractions during feeding rats a high fat diet (HFD) for 5 weeks. Moreover, the relation between changes in myocardial lipid content, whole body insulin resistance and the expression of fatty acid transporters in each week of HFD was established. Methods: Gas liquid chromatography and high performance liquid chromatography were used to determine the content of lipid fractions in the left ventricle. Expression of selected proteins was estimated by Western blot technique. All measurements were made after each week of HFD. Results: As expected, lipid profile in myocardium was altered by HFD in different weeks of the study with the most intense changes in triacylglycerols, long chain fatty acid-CoA and ceramide. Furthermore, there was a significant elevation of plasmalemmal (the 4th and the 5th week) and mitochondrial expression (from the 3rd to the 5th week) of fatty acid translocase. Conclusion: High fat diet affects myocardial lipid profile in each week of its duration and causes alternations in FA metabolism in cardiomyocytes.

Analysis of the liver lipidome reveals insights into the protective effect of exercise on high-fat diet-induced hepatosteatosis in mice

2015 ◽  
Vol 308 (9) ◽  
pp. E778-E791 ◽  
Author(s):  
Andreas B. Jordy ◽  
Michael J. Kraakman ◽  
Tim Gardner ◽  
Emma Estevez ◽  
Helene L. Kammoun ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Fatty Acid ◽  
Membrane Integrity ◽  
Treadmill Running ◽  
Whole Body ◽  
Oral Glucose ◽  
High Fat ◽  
Lipid Species ◽  
Fat Feeding

The accumulation of lipid at ectopic sites, including the skeletal muscle and liver, is a common consequence of obesity and is associated with tissue-specific and whole body insulin resistance. Exercise is well known to improve insulin resistance by mechanisms not completely understood. We performed lipidomic profiling via mass spectrometry in liver and skeletal muscle samples from exercise-trained mice to decipher the lipid changes associated with exercise-induced improvements in whole body glucose metabolism. Obesity and insulin resistance were induced in C57BL/6J mice by high-fat feeding for 4 wk. Mice then underwent an exercise training program (treadmill running) 5 days/wk (Ex) for 4 wk or remained sedentary (Sed). Compared with Sed, Ex displayed improved ( P < 0.01) whole body metabolism as measured via an oral glucose tolerance test. Deleterious lipid species such as diacylglycerol ( P < 0.05) and cholesterol esters ( P < 0.01) that accumulate with high-fat feeding were decreased in the liver of trained mice. Furthermore, the ratio of phosphatidylcholine (PC) to phosphatidylethanolamine (PE) (the PC/PE ratio), which is associated with membrane integrity and linked to hepatic disease progression, was increased by training ( P < 0.05). These findings occurred without corresponding changes in the skeletal muscle lipidome. A concomitant decrease ( P < 0.05) was observed for the fatty acid transporters CD36 and FATP4 in the liver, suggesting that exercise stimulates a coordinated reduction in fatty acid entry into hepatocytes. Given the important role of the liver in the regulation of whole body glucose homeostasis, hepatic lipid regression may be a key component by which exercise can improve metabolism.

scholarly journals Intrinsic aerobic capacity impacts susceptibility to acute high-fat diet-induced hepatic steatosis

2014 ◽  
Vol 307 (4) ◽  
pp. E355-E364 ◽  
Author(s):  
E. Matthew Morris ◽  
Matthew R. Jackman ◽  
Ginger C. Johnson ◽  
Tzu-Wen Liu ◽  
Jordan L. Lopez ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Energy Expenditure ◽  
Fatty Liver ◽  
Lipid Oxidation ◽  
Hepatic Steatosis ◽  
Aerobic Capacity ◽  
High Fat Diet ◽  
Whole Body ◽  
Acid Oxidation ◽  
High Fat

Aerobic capacity/fitness significantly impacts susceptibility for fatty liver and diabetes, but the mechanisms remain unknown. Herein, we utilized rats selectively bred for high (HCR) and low (LCR) intrinsic aerobic capacity to examine the mechanisms by which aerobic capacity impacts metabolic vulnerability for fatty liver following a 3-day high-fat diet (HFD). Indirect calorimetry assessment of energy metabolism combined with radiolabeled dietary food was employed to examine systemic metabolism in combination with ex vivo measurements of hepatic lipid oxidation. The LCR, but not HCR, displayed increased hepatic lipid accumulation in response to the HFD despite both groups increasing energy intake. However, LCR rats had a greater increase in energy intake and demonstrated greater daily weight gain and percent body fat due to HFD compared with HCR. Additionally, total energy expenditure was higher in the larger LCR. However, controlling for the difference in body weight, the LCR has lower resting energy expenditure compared with HCR. Importantly, respiratory quotient was significantly higher during the HFD in the LCR compared with HCR, suggesting reduced whole body lipid utilization in the LCR. This was confirmed by the observed lower whole body dietary fatty acid oxidation in LCR compared with HCR. Furthermore, LCR liver homogenate and isolated mitochondria showed lower complete fatty acid oxidation compared with HCR. We conclude that rats bred for low intrinsic aerobic capacity show greater susceptibility for dietary-induced hepatic steatosis, which is associated with a lower energy expenditure and reduced whole body and hepatic mitochondrial lipid oxidation.

Time course of insulin resistance associated with feeding dogs a high-fat diet

1997 ◽  
Vol 272 (1) ◽  
pp. E147-E154 ◽  
Author(s):  
A. P. Rocchini ◽  
P. Marker ◽  
T. Cervenka
Keyword(s):  
Insulin Resistance ◽  
Blood Pressure ◽  
Glucose Uptake ◽  
Dose Response ◽  
High Fat Diet ◽  
Time Course ◽  
Rapid Development ◽  
Diet Group ◽  
Whole Body ◽  
High Fat

The current study evaluated both the time course of insulin resistance associated with feeding dogs a high-fat diet and the relationship between the development of insulin resistance and the increase in blood pressure that also occurs. Twelve adult mongrel dogs were chronically instrumented and randomly assigned to either a control diet group (n = 4) or a high-fat diet group (n = 8). Insulin resistance was assessed by a weekly, single-dose (2 mU.kg-1.min-1) euglycemic-hyperinsulinemic clamp on all dogs. Feeding dogs a high-fat diet was associated with a 3.7 +/- 0.5 kg increase in body weight, a 20 +/- 4 mmHg increase in mean blood pressure, a reduction in insulin-mediated glucose uptake [(in mumol-kg-1.min-1) decreasing from 72 +/- 6 before to 49 +/- 7 at 1 wk, 29 +/- 3 at 3 wk, and 30 +/- 2 at 6 wk of the high-fat diet, P < 0.01]. and a reduced insulin-mediated increase in cardiac output. In eight dogs (4 high fat and 4 control), the dose-response relationship of insulin-induced glucose uptake also was studied. The whole body glucose uptake dose-response curve was shifted to the right, and the rate of maximal whole body glucose uptake was significantly decreased (P < 0.001). Finally, we observed a direct relationship between the high-fat diet-induced weekly increase in mean arterial pressure and the degree to which insulin resistance developed. In summary, the current study documents that feeding dogs a high-fat diet causes the rapid development of insulin resistance that is the result of both a reduced sensitivity and a reduced responsiveness to insulin.

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