scholarly journals The Sphingosine-1-Phosphate Analog FTY720 Reduces Muscle Ceramide Content and Improves Glucose Tolerance in High Fat-Fed Male Mice

Endocrinology ◽  
2013 ◽  
Vol 154 (1) ◽  
pp. 65-76 ◽  
Author(s):  
Clinton R. Bruce ◽  
Steve Risis ◽  
Joanne R. Babb ◽  
Christine Yang ◽  
Robert S. Lee-Young ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Lipid Metabolism ◽  
Glucose Tolerance ◽  
Glucose Homeostasis ◽  
Whole Body ◽  
Sphingolipid Metabolism ◽  
High Fat ◽  
Sphingosine 1 Phosphate ◽  
Ceramide Content ◽  
Ceramide Accumulation

FTY720 is a sphingosine-1-phosphate analog that has been shown to inhibit ceramide synthesis in vitro. Because ceramide accumulation in muscle is associated with insulin resistance, we aimed to examine whether FTY720 would prevent muscle ceramide accumulation in high fat-fed mice and subsequently improve glucose homeostasis. Male C57Bl/6 mice were fed either a chow or high fat-diet (HFD) for 6 wk, after which they were treated with vehicle or FTY720 (5 mg/kg) daily for a further 6 wk. The ceramide content of muscle was examined and insulin action was assessed. Whereas the HFD increased muscle ceramide, this was prevented by FTY720 treatment. This was not associated with alterations in the expression of genes involved in sphingolipid metabolism. Interestingly, the effects of FTY720 on lipid metabolism were not limited to ceramide because FTY720 also prevented the HFD-induced increase in diacylglycerol and triacylglycerol in muscle. Furthermore, the increase in CD36 mRNA expression induced by fat feeding was prevented in muscle of FTY720-treated mice. This was associated with an attenuation of the HFD-induced increase in palmitate uptake and esterification. In addition, FTY720 improved glucose homeostasis as demonstrated by a reduction in plasma insulin, an improvement in whole-body glucose tolerance, an increase in insulin-stimulated glucose uptake, and Akt phosphorylation in muscle. In conclusion, FTY720 exerts beneficial effects on muscle lipid metabolism that prevent lipid accumulation and improve glucose tolerance in high fat-fed mice. Thus, FTY720 and other compounds that target sphingosine-1-phosphate signaling may have therapeutic potential in treating insulin resistance.

scholarly journals Melatonin Improves Glucose Homeostasis and Endothelial Vascular Function in High-Fat Diet-Fed Insulin-Resistant Mice

Endocrinology ◽  
2009 ◽  
Vol 150 (12) ◽  
pp. 5311-5317 ◽  
Author(s):  
Claudio Sartori ◽  
Pierre Dessen ◽  
Caroline Mathieu ◽  
Anita Monney ◽  
Jonathan Bloch ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Signal Transduction ◽  
Glucose Tolerance ◽  
Glucose Homeostasis ◽  
High Fat Diet ◽  
High Fat ◽  
Insulin Resistant ◽  
Normal Chow ◽  
Underlying Mechanisms

Abstract Obesity and insulin resistance represent a problem of utmost clinical significance worldwide. Insulin-resistant states are characterized by the inability of insulin to induce proper signal transduction leading to defective glucose uptake in skeletal muscle tissue and impaired insulin-induced vasodilation. In various pathophysiological models, melatonin interacts with crucial molecules of the insulin signaling pathway, but its effects on glucose homeostasis are not known. In a diet-induced mouse model of insulin resistance and normal chow-fed control mice, we sought to assess the effects of an 8-wk oral treatment with melatonin on insulin and glucose tolerance and to understand underlying mechanisms. In high-fat diet-fed mice, but not in normal chow-fed control mice, melatonin significantly improved insulin sensitivity and glucose tolerance, as evidenced by a higher rate of glucose infusion to maintain euglycemia during hyperinsulinemic clamp studies and an attenuated hyperglycemic response to an ip glucose challenge. Regarding underlying mechanisms, we found that melatonin restored insulin-induced vasodilation to skeletal muscle, a major site of glucose utilization. This was due, at least in part, to the improvement of insulin signal transduction in the vasculature, as evidenced by increased insulin-induced phosphorylation of Akt and endoethelial nitric oxide synthase in aortas harvested from melatonin-treated high-fat diet-fed mice. In contrast, melatonin had no effect on the ability of insulin to promote glucose uptake in skeletal muscle tissue in vitro. These data demonstrate for the first time that in a diet-induced rodent model of insulin resistance, melatonin improves glucose homeostasis by restoring the vascular action of insulin.

scholarly journals Antioxidants Supplementation Reduces Ceramide Synthesis Improving the Cardiac Insulin Transduction Pathway in a Rodent Model of Obesity

Nutrients ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 3413
Author(s):  
Katarzyna Hodun ◽  
Klaudia Sztolsztener ◽  
Adrian Chabowski
Keyword(s):  
Lipid Metabolism ◽  
Insulin Signaling ◽  
High Performance ◽  
Sphingolipid Metabolism ◽  
Intragastric Administration ◽  
Transduction Pathway ◽  
Ceramide Synthesis ◽  
Sphingosine 1 Phosphate ◽  
Male Wistar Rats ◽  
Ceramide Accumulation

Obesity-related disruption in lipid metabolism contributes to cardiovascular dysfunction. Despite numerous studies on lipid metabolism in the left ventricle, there is no data describing the influence of n-acetylcysteine (NAC) and α-lipoic acid (ALA), as glutathione precursors, on sphingolipid metabolism, and insulin resistance (IR) occurrence. The aim of our experiment was to evaluate the influence of chronic antioxidants administration on myocardial sphingolipid state and intracellular insulin signaling as a potential therapeutic strategy for obesity-related cardiovascular IR. The experiment was conducted on male Wistar rats fed a standard rodent chow or a high-fat diet with intragastric administration of NAC or ALA for eight weeks. Cardiac and plasma sphingolipid species were assessed by high-performance liquid chromatography (HPLC). The proteins expressed from sphingolipid and insulin signaling pathways were determined by Western blot. Antioxidant supplementation markedly reduced ceramide accumulation by lowering the expression of selected proteins from the sphingolipid pathway and simultaneously increased the myocardial sphingosine-1-phosphate level. Moreover, NAC and ALA augmented the expression of GLUT4 and the phosphorylation state of Akt (Ser473) and GSK3β (Ser9), which improved the intracellular insulin transduction pathway. Based on our results, we may postulate that NAC and ALA have a beneficial influence on the cardiac ceramidose under IR conditions.

scholarly journals High-fat diet-induced impairment of skeletal muscle insulin sensitivity is not prevented by SIRT1 overexpression

2014 ◽  
Vol 307 (9) ◽  
pp. E764-E772 ◽  
Author(s):  
Amanda T. White ◽  
Andrew Philp ◽  
Heidi N. Fridolfsson ◽  
Jan M. Schilling ◽  
Anne N. Murphy ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Energy Expenditure ◽  
Glucose Tolerance ◽  
Glucose Uptake ◽  
High Fat Diet ◽  
Sirtuin 1 ◽  
Whole Body ◽  
Oral Glucose ◽  
High Fat

Skeletal muscle sirtuin 1 (SIRT1) expression is reduced under insulin-resistant conditions, such as those resulting from high-fat diet (HFD) feeding and obesity. Herein, we investigated whether constitutive activation of SIRT1 in skeletal muscle prevents HFD-induced muscle insulin resistance. To address this, mice with muscle-specific overexpression of SIRT1 (mOX) and wild-type (WT) littermates were fed a control diet (10% calories from fat) or HFD (60% of calories from fat) for 12 wk. Magnetic resonance imaging and indirect calorimetry were used to measure body composition and energy expenditure, respectively. Whole body glucose metabolism was assessed by oral glucose tolerance test, and insulin-stimulated glucose uptake was measured at a physiological insulin concentration in isolated soleus and extensor digitorum longus muscles. Although SIRT1 was significantly overexpressed in muscle of mOX vs. WT mice, body weight and percent body fat were similarly increased by HFD for both genotypes, and energy expenditure was unaffected by diet or genotype. Importantly, impairments in glucose tolerance and insulin-mediated activation of glucose uptake in skeletal muscle that occurred with HFD feeding were not prevented in mOX mice. In contrast, mOX mice showed enhanced postischemic cardiac functional recovery compared with WT mice, confirming the physiological functionality of the SIRT1 transgene in this mouse model. Together, these results demonstrate that activation of SIRT1 in skeletal muscle alone does not prevent HFD-induced glucose intolerance, weight gain, or insulin resistance.

Acute activation of central GLP-1 receptors enhances hepatic insulin action and insulin secretion in high-fat-fed, insulin resistant mice

2012 ◽  
Vol 302 (3) ◽  
pp. E334-E343 ◽  
Author(s):  
Melissa A. Burmeister ◽  
Tura Ferre ◽  
Jennifer E. Ayala ◽  
Emily M. King ◽  
Rochelle M. Holt ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Glucose Homeostasis ◽  
Insulin Action ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Whole Body ◽  
High Fat ◽  
Intravenous Glucose ◽  
Insulin Levels ◽  
Triglyceride Accumulation

Glucagon-like peptide-1 (GLP-1) receptor knockout (Glp1r−/−) mice exhibit impaired hepatic insulin action. High fat (HF)-fed Glp1r−/− mice exhibit improved, rather than the expected impaired, hepatic insulin action. This is due to decreased lipogenic gene expression and triglyceride accumulation. The present studies overcome these secondary adaptations by acutely modulating GLP-1R action in HF-fed wild-type mice. The central GLP-1R was targeted given its role as a regulator of hepatic insulin action. We hypothesized that acute inhibition of the central GLP-1R impairs hepatic insulin action beyond the effects of HF feeding. We further hypothesized that activation of the central GLP-1R improves hepatic insulin action in HF-fed mice. Insulin action was assessed in conscious, unrestrained mice using the hyperinsulinemic euglycemic clamp. Mice received intracerebroventricular (icv) infusions of artificial cerebrospinal fluid, GLP-1, or the GLP-1R antagonist exendin-9 (Ex-9) during the clamp. Intracerebroventricular Ex-9 impaired the suppression of hepatic glucose production by insulin, whereas icv GLP-1 improved it. Neither treatment affected tissue glucose uptake. Intracerebroventricular GLP-1 enhanced activation of hepatic Akt and suppressed hypothalamic AMP-activated protein kinase. Central GLP-1R activation resulted in lower hepatic triglyceride levels but did not affect muscle, white adipose tissue, or plasma triglyceride levels during hyperinsulinemia. In response to oral but not intravenous glucose challenges, activation of the central GLP-1R improved glucose tolerance. This was associated with higher insulin levels. Inhibition of the central GLP-1R had no effect on oral or intravenous glucose tolerance. These results show that inhibition of the central GLP-1R deteriorates hepatic insulin action in HF-fed mice but does not affect whole body glucose homeostasis. Contrasting this, activation of the central GLP-1R improves glucose homeostasis in HF-fed mice by increasing insulin levels and enhancing hepatic insulin action.

scholarly journals Antisense oligonucleotides against monoacylglycerol acyltransferase 1 (Mogat1) improve glucose metabolism independently of Mogat1

2020 ◽  
Author(s):  
Andrew J. Lutkewitte ◽  
Jason M. Singer ◽  
Trevor M. Shew ◽  
Michael R. Martino ◽  
Angela M. Hall ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Glucose Metabolism ◽  
Glucose Tolerance ◽  
High Fat Diet ◽  
Hepatic Insulin Resistance ◽  
Whole Body ◽  
High Fat ◽  
Target Effects ◽  
Monoacylglycerol Acyltransferase

ABSTRACTObjectiveMonoacylglycerol acyltransferase (MGAT) enzymes catalyze the synthesis of diacylglycerol from monoacylglycerol. Previous work has suggested the importance of MGAT activity in the development of obesity-related hepatic insulin resistance. Indeed, antisense oligonucleotide (ASO)-mediated knockdown of the gene encoding MGAT1, Mogat1, reduced hepatic MGAT activity and improved glucose tolerance and insulin resistance in high fat diet (HFD) fed mice. However, recent work has suggested that some ASOs may have off-target effects on body weight and metabolic parameters via activation of the interferon alpha/beta receptor 1 (IFNAR-1) pathway.MethodsMice with whole-body Mogat1 knockout or a floxed allele for Mogat1 to allow for liver-specific Mogat1-knockout (by either a liver-specific transgenic or adeno-associated virus-driven Cre recombinase) were generated. These mice were placed on a high fat diet and glucose metabolism and insulin sensitivity was assessed after 16 weeks on diet. In some experiments, mice were treated with control or Mogat1 or control ASOs in the presence or absence of IFNAR-1 neutralizing antibody.ResultsGenetic deletion of hepatic Mogat1, either acutely or chronically, did not improve hepatic steatosis, glucose tolerance, or insulin sensitivity in HFD-fed mice. Furthermore, constitutive Mogat1 knockout in all tissues actually exacerbated HFD-induced weight gain, insulin resistance, and glucose intolerance on a HFD. Despite markedly reduced Mogat1 expression, liver MGAT activity was unaffected in all knockout mouse models. Mogat1 overexpression hepatocytes increased liver MGAT activity and TAG content in low-fat fed mice, but did not cause insulin resistance. Interestingly, Mogat1 ASO treatment improved glucose tolerance in both wild-type and Mogat1 null mice, suggesting an off target effect. Inhibition of IFNAR-1 did not block the effect of Mogat1 ASO on glucose homeostasis.ConclusionThese results indicate that genetic loss of Mogat1 does not affect hepatic MGAT activity or metabolic homeostasis on HFD and show that Mogat1 ASOs improve glucose metabolism through effects independent of targeting Mogat1 or activation of IFNAR-1 signaling.Abstract FigureHighlightsMogat1 liver-specific KO or KD does not improve metabolism in HFD fed mice.Whole-body Mogat1-deletion impairs insulin tolerance in HFD fed mice.Mogat1 ASOs improves whole body metabolism independently of gene knockdown.Blockade of the INFR response does not prevent off-target effects of Mogat1 ASOs.

Predominant Role of GIP in the Development of a Metabolic Syndrome-like Phenotype in Female Wistar Rats Submitted to Forced Catch-up Growth

Endocrinology ◽  
2014 ◽  
Vol 155 (10) ◽  
pp. 3769-3780 ◽  
Author(s):  
J. De Toro-Martín ◽  
E. Fernández-Millán ◽  
E. Lizárraga-Mollinedo ◽  
E. López-Oliva ◽  
P. Serradas ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Glucose Tolerance ◽  
Glucose Homeostasis ◽  
Visceral Fat ◽  
Female Rats ◽  
Dependent Manner ◽  
High Fat ◽  
Adipocyte Hypertrophy ◽  
Catch Up

Abstract Catch-up growth has been associated with the appearance of metabolic dysfunctions such as obesity and type 2 diabetes in adulthood. Because the entero-insular axis is critical to glucose homeostasis control, we explored the relevance of the incretins glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) in the development of these pathologies. Offspring of rat dams fed ad libitum (control [C]) or 65% food-restricted during pregnancy and suckling time (undernourished [U]) were weaned onto a high-fat (HF) diet (CHF and UHF, respectively) to drive catch-up growth. Both male and female UHF rats showed an obese phenotype characterized by hyperphagy, visceral fat accumulation, and adipocyte hypertrophy. High-fat diet induced deterioration of glucose tolerance in a sex-dependent manner. Female UHF rats experienced much more severe glucose intolerance than males, which was not compensated by insulin hypersecretion, suggesting insulin resistance, as shown by homeostatic model assessment of insulin resistance values. Moreover, female, but not male, UHF rats displayed enhanced GIP but not GLP-1 secretion during oral glucose tolerance test. Administration of the GIP receptor antagonist (Pro3)GIP to UHF female rats over 21 days markedly reduced visceral fat mass and adipocyte hypertrophy without variations in food intake or body weight. These changes were accompanied by improvement of glucose tolerance and insulin sensitivity. In conclusion, the exacerbated production and secretion of GIP after the catch-up growth seems to represent the stimulus for insulin hypersecretion and insulin resistance, ultimately resulting in derangement of glucose homeostasis. Overall, these data evidence the role of GIP as a critical link between catch-up growth and the development of metabolic disturbances.

Anti-obesity effects of Grifola frondosa through the modulation of lipid metabolism via ceramide in mice fed a high-fat diet

2021 ◽  
Author(s):  
Xue Jiang ◽  
Jie Hao ◽  
Zijian Liu ◽  
Xueting Ma ◽  
Yuxin Feng ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Lipid Metabolism ◽  
High Fat Diet ◽  
Fat Deposition ◽  
Grifola Frondosa ◽  
High Fat ◽  
Metabolic Complications ◽  
Basidiomycete Fungus

Obesity is characterized by massive fat deposition and is related to a series of metabolic complications, such as insulin resistance (IR) and steatohepatitis. Grifola frondosa (GF) is a basidiomycete fungus...

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.

Whole body insulin resistance in rat offspring of mothers consuming alcohol during pregnancy or lactation: comparing prenatal and postnatal exposure

2004 ◽  
Vol 96 (1) ◽  
pp. 167-172 ◽  
Author(s):  
Li Chen ◽  
B. L. Grégoire Nyomba
Keyword(s):  
Insulin Resistance ◽  
Birth Weight ◽  
Glucose Tolerance ◽  
The Body ◽  
Whole Body ◽  
Glucose Disposal ◽  
Tolerance Index ◽  
Sensitivity Index ◽  
Intravenous Glucose ◽  
Rat Offspring

This study examined the effects of maternal ethanol (EtOH) consumption during pregnancy or lactation on glucose homeostasis in the adult rat offspring. Glucose disposal was determined by minimal model during an intravenous glucose tolerance test in rats that had a small or normal birth weight after EtOH exposure in utero and in rats whose mothers were given EtOH during lactation only. All three EtOH groups had decreased glucose tolerance index and insulin sensitivity index, but their glucose effectiveness was not different from that of controls. In addition, EtOH rat offspring that were small at birth had elevated plasma, liver, and muscle triglyceride levels. The data show that EtOH exposure during pregnancy programs the body to insulin resistance later in life, regardless of birth weight, but that this effect also results in dyslipidemia in growth-restricted rats. In addition, insulin resistance is also evident after EtOH exposure during lactation.

scholarly journals Effects of Micronutrient Supplementation on Glucose and Hepatic Lipid Metabolism in a Rat Model of Diet Induced Obesity

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1751
Author(s):  
Saroj Khatiwada ◽  
Virginie Lecomte ◽  
Michael F. Fenech ◽  
Margaret J. Morris ◽  
Christopher A. Maloney
Keyword(s):  
Insulin Resistance ◽  
Lipid Metabolism ◽  
Glucose Tolerance ◽  
Antioxidant Capacity ◽  
Fasting Glucose ◽  
Oral Glucose ◽  
Model Assessment ◽  
Micronutrient Supplementation ◽  
Sprague Dawley ◽  
Triglyceride Accumulation

Obesity increases the risk of metabolic disorders, partly through increased oxidative stress. Here, we examined the effects of a dietary micronutrient supplement (consisting of folate, vitamin B6, choline, betaine, and zinc) with antioxidant and methyl donor activities. Male Sprague Dawley rats (3 weeks old, 17/group) were weaned onto control (C) or high-fat diet (HFD) or same diets with added micronutrient supplement (CS; HS). At 14.5 weeks of age, body composition was measured by magnetic resonance imaging. At 21 weeks of age, respiratory quotient and energy expenditure was measured using Comprehensive Lab Animal Monitoring System. At 22 weeks of age, an oral glucose tolerance test (OGTT) was performed, and using fasting glucose and insulin values, Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) was calculated as a surrogate measure of insulin resistance. At 30.5 weeks of age, blood and liver tissues were harvested. Liver antioxidant capacity, lipids and expression of genes involved in lipid metabolism (Cd36, Fabp1, Acaca, Fasn, Cpt1a, Srebf1) were measured. HFD increased adiposity (p < 0.001) and body weight (p < 0.001), both of which did not occur in the HS group. The animals fed HFD developed impaired fasting glucose, impaired glucose tolerance, and fasting hyperinsulinemia compared to control fed animals. Interestingly, HS animals demonstrated an improvement in fasting glucose and fasting insulin. Based on insulin release during OGTT and HOMA-IR, the supplement appeared to reduce the insulin resistance developed by HFD feeding. Supplementation increased hepatic glutathione content (p < 0.05) and reduced hepatic triglyceride accumulation (p < 0.001) regardless of diet; this was accompanied by altered gene expression (particularly of CPT-1). Our findings show that dietary micronutrient supplementation can reduce weight gain and adiposity, improve glucose metabolism, and improve hepatic antioxidant capacity and lipid metabolism in response to HFD intake.

Sign in / Sign up

Export Citation Format

Share Document