scholarly journals Improvement of Insulin Sensitivity after Peroxisome Proliferator-Activated Receptor-α Agonist Treatment Is Accompanied by Paradoxical Increase of Circulating Resistin Levels

Endocrinology ◽  
2006 ◽  
Vol 147 (9) ◽  
pp. 4517-4524 ◽  
Author(s):  
M. M. Haluzik ◽  
Z. Lacinova ◽  
M. Dolinkova ◽  
D. Haluzikova ◽  
D. Housa ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Mrna Expression ◽  
Liver Steatosis ◽  
Tissue Expression ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Insulin Levels ◽  
Fenofibrate Treatment ◽  
Adiponectin Mrna

We studied the effect of peroxisome proliferator-activated receptor-α (PPAR-α) activation on serum concentrations and tissue expression of resistin, adiponectin, and adiponectin receptor-1 and -2 (AdipoR1 and AdipoR2) mRNA in normal mice and mice with insulin resistance induced by lipogenic, simple-carbohydrate diet (LD). Sixteen weeks of LD feeding induced obesity with liver steatosis and increased insulin levels but did not significantly affect circulating adiponectin or resistin. Treatment with PPAR-α agonist fenofibrate decreased body weight and fat pad weight and ameliorated liver steatosis in LD-fed mice with concomitant reduction in blood glucose, free fatty acid, triglyceride, serum insulin levels, and homeostasis model assessment index values. Euglycemic-hyperinsulinemic clamp demonstrated the development of whole-body and liver insulin resistance in LD-fed mice, which were both normalized by fenofibrate. Fenofibrate treatment markedly increased circulating resistin levels on both diets and adiponectin levels in chow-fed mice only. Fat adiponectin mRNA expression was not affected by fenofibrate treatment. Resistin mRNA expression increased in subcutaneous but not gonadal fat after fenofibrate treatment. In addition to fat, a significant amount of adiponectin mRNA was also expressed in the muscle. This expression markedly increased after fenofibrate treatment in chow- but not in LD-fed mice. Adipose tissue expression of AdipoR1 mRNA was significantly reduced in LD-fed mice and increased after fenofibrate treatment. In conclusion, PPAR-α activation ameliorated the development of insulin resistance in LD-fed mice despite a major increase in serum resistin levels. This effect could be partially explained by increased AdipoR1 expression in adipose tissue after fenofibrate treatment.

scholarly journals The effects of obesity-associated insulin resistance on mRNA expression of peroxisome proliferator-activated receptor-γ target genes, in dogs

2007 ◽  
Vol 98 (3) ◽  
pp. 497-503 ◽  
Author(s):  
Constance Gayet ◽  
Veronique Leray ◽  
Masayuki Saito ◽  
Brigitte Siliart ◽  
Patrick Nguyen
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Insulin Sensitivity ◽  
Mrna Expression ◽  
Target Genes ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Glucose And Lipid Metabolism ◽  
Visceral Adipose

Visceral adipose tissue and skeletal muscle have central roles in determining whole-body insulin sensitivity. The peroxisome proliferator-activated receptor-γ (PPARγ) is a potential mediator of insulin sensitivity. It can directly modulate the expression of genes that are involved in glucose and lipid metabolism, including GLUT4, lipoprotein lipase (LPL) and adipocytokines (leptin and adiponectin). In this study, we aimed to determine the effects of obesity-associated insulin resistance on mRNA expression of PPARγ and its target genes. Dogs were studied when they were lean and at the end of an overfeeding period when they had reached a steady obese state. The use of a sensitive, real-time PCR assay allowed a relative quantification of mRNA expression for PPARγ, LPL, GLUT4, leptin and adiponectin, in adipose tissue and skeletal muscle. In visceral adipose tissue and/or skeletal muscle, mRNA expression of PPARγ, LPL and GLUT4 were at least 2-fold less in obese and insulin-resistant dogs compared with the same animals when they were lean and insulin-sensitive. The mRNA expression and plasma concentration of leptin was increased, whereas the plasma level and mRNA expression of adiponectin was decreased, by obesity. In adipose tissue, PPARγ expression was correlated with leptin and adiponectin. These findings, in an original model of obesity induced by a prolonged period of overfeeding, showed that insulin resistance is associated with a decrease in PPARγ mRNA expression that could dysregulate expression of several genes involved in glucose and lipid metabolism.

PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR GAMMA AND GROWTH HORMONE SEGRETAGOGUE RECEPTOR-1A MRNA EXPRESSION IN ADIPOSE TISSUE OBTAINED FROM SEVERELY OBESE PATIENTS

2018 ◽  
Vol 25 (3) ◽  
pp. 219
Author(s):  
Bianca Codrina Morarasu ◽  
Raluca Ecaterina Haliga ◽  
Daniel Timofte ◽  
Ioana Hristov ◽  
Iustina Silivestru-Cretu ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Adipose Tissue ◽  
Mrna Expression ◽  
Peroxisome Proliferator ◽  
Obese Patients ◽  
Peroxisome Proliferator Activated Receptor ◽  
Severely Obese

scholarly journals Peroxisome Proliferator-Activated Receptor γ and Adipose Tissue—Understanding Obesity-Related Changes in Regulation of Lipid and Glucose Metabolism

2006 ◽  
Vol 92 (2) ◽  
pp. 386-395 ◽  
Author(s):  
Arya M. Sharma ◽  
Bart Staels
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Metabolic Syndrome ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Endocrine Function ◽  
Low Grade ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor

Abstract Context: Adipose tissue is a metabolically dynamic organ, serving as a buffer to control fatty acid flux and a regulator of endocrine function. In obese subjects, and those with type 2 diabetes or the metabolic syndrome, adipose tissue function is altered (i.e. adipocytes display morphological differences alongside aberrant endocrine and metabolic function and low-grade inflammation). Evidence Acquisition: Articles on the role of peroxisome proliferator-activated receptor γ (PPARγ) in adipose tissue of healthy individuals and those with obesity, metabolic syndrome, or type 2 diabetes were sourced using MEDLINE (1990–2006). Evidence Synthesis: Articles were assessed to provide a comprehensive overview of how PPARγ-activating ligands improve adipose tissue function, and how this links to improvements in insulin resistance and the progression to type 2 diabetes and atherosclerosis. Conclusions: PPARγ is highly expressed in adipose tissue, where its activation with thiazolidinediones alters fat topography and adipocyte phenotype and up-regulates genes involved in fatty acid metabolism and triglyceride storage. Furthermore, PPARγ activation is associated with potentially beneficial effects on the expression and secretion of a range of factors, including adiponectin, resistin, IL-6, TNFα, plasminogen activator inhibitor-1, monocyte chemoattractant protein-1, and angiotensinogen, as well as a reduction in plasma nonesterified fatty acid supply. The effects of PPARγ also extend to macrophages, where they suppress production of inflammatory mediators. As such, PPARγ activation appears to have a beneficial effect on the relationship between the macrophage and adipocyte that is distorted in obesity. Thus, PPARγ-activating ligands improve adipose tissue function and may have a role in preventing progression of insulin resistance to diabetes and endothelial dysfunction to atherosclerosis.

scholarly journals Developmental Programming: Differential Effects of Prenatal Testosterone Excess on Insulin Target Tissues

2010 ◽  
Vol 31 (5) ◽  
pp. 775-775
Author(s):  
Shadia E. Nada ◽  
Robert C. Thompson ◽  
Vasantha Padmanabhan
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Insulin Receptor ◽  
Glycogen Synthase ◽  
Hormone Sensitive Lipase ◽  
Initiation Factor ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Peripheral Tissues ◽  
Prenatal Testosterone

Polycystic ovarian syndrome (PCOS) is the leading cause of infertility in reproductive-aged women with the majority manifesting insulin resistance. To delineate the causes of insulin resistance in women with PCOS, we determined changes in the mRNA expression of insulin receptor (IR) isoforms and members of its signaling pathway in tissues of adult control (n = 7) and prenatal testosterone (T)-treated (n = 6) sheep (100 mg/kg twice a week from d 30-90 of gestation), the reproductive/metabolic characteristics of which are similar to women with PCOS. Findings revealed that prenatal T excess reduced (P < 0.05) expression of IR-B isoform (only isoform detected), insulin receptor substrate-2 (IRS-2), protein kinase B (AKt), peroxisome proliferator-activated receptor-γ (PPARγ), hormone-sensitive lipase (HSL), and mammalian target of rapamycin (mTOR) but increased expression of rapamycin-insensitive companion of mTOR (rictor), and eukaryotic initiation factor 4E (eIF4E) in the liver. Prenatal T excess increased (P < 0.05) the IR-A to IR-B isoform ratio and expression of IRS-1, glycogen synthase kinase-3α and -β (GSK-3α and -β), and rictor while reducing ERK1 in muscle. In the adipose tissue, prenatal T excess increased the expression of IRS-2, phosphatidylinositol 3-kinase (PI3K), PPARγ, and mTOR mRNAs. These findings provide evidence that prenatal T excess modulates in a tissue-specific manner the expression levels of several genes involved in mediating insulin action. These changes are consistent with the hypothesis that prenatal T excess disrupts the insulin sensitivity of peripheral tissues, with liver and muscle being insulin resistant and adipose tissue insulin sensitive.

scholarly journals Whey Peptides Stimulate Differentiation and Lipid Metabolism in Adipocytes and Ameliorate Lipotoxicity-Induced Insulin Resistance in Muscle Cells

Nutrients ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 425 ◽  
Author(s):  
Kenneth D’Souza ◽  
Angella Mercer ◽  
Hannah Mawhinney ◽  
Thomas Pulinilkunnil ◽  
Chibuike C. Udenigwe ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Lipid Metabolism ◽  
Milk Proteins ◽  
C2c12 Myotubes ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Systemic Insulin Resistance ◽  
Skeletal Myotubes

Deregulation of lipid metabolism and insulin function in muscle and adipose tissue are hallmarks of systemic insulin resistance, which can progress to type 2 diabetes. While previous studies suggested that milk proteins influence systemic glucose homeostasis and insulin function, it remains unclear whether bioactive peptides generated from whey alter lipid metabolism and its accumulation in muscle and adipose tissue. Therefore, we incubated murine 3T3-L1 preadipocytes and C2C12 myotubes with a whey peptide mixture produced through pepsin-pancreatin digestion, mimicking peptides generated in the gut from whey protein hydrolysis, and examined its effect on indicators of lipid metabolism and insulin sensitivity. Whey peptides, particularly those derived from bovine serum albumin (BSA), promoted 3T3-L1 adipocyte differentiation and triacylglycerol (TG) accumulation in accordance with peroxisome proliferator-activated receptor γ (PPARγ) upregulation. Whey/BSA peptides also increased lipolysis and mitochondrial fat oxidation in adipocytes, which was associated with the upregulation of peroxisome proliferator-activated receptor δ (PPARδ). In C2C12 myotubes, whey but not BSA peptides ameliorated palmitate-induced insulin resistance, which was associated with reduced inflammation and diacylglycerol accumulation, and increased sequestration of fatty acids in the TG pool. Taken together, our study suggests that whey peptides generated via pepsin-pancreatin digestion profoundly alter lipid metabolism and accumulation in adipocytes and skeletal myotubes.

Changes in adipokine expression during food deprivation in the mouse and the relationship to fasting-induced insulin resistance

2003 ◽  
Vol 81 (10) ◽  
pp. 979-985 ◽  
Author(s):  
Yaoting Gui ◽  
Josef V Silha ◽  
Suresh Mishra ◽  
Liam J Murphy
Keyword(s):  
Insulin Resistance ◽  
Food Deprivation ◽  
Tissue Expression ◽  
Brown Fat ◽  
Mrna Abundance ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ ◽  
Plasma Leptin

We investigated the changes in insulin resistance and adipose tissue expression of the adipokines resistin, adiponectin, and leptin and the transcription factors peroxisome proliferator-activated receptor-γ (PPAR-γ) and retinoid X receptor-α (RXR-α) during 48 h of food deprivation. Insulin sensitivity (SI) declined, whereas glucose effectiveness (SG) increased. Plasma adiponectin levels declined in the first 8 h and remained constant thereafter. There was no correlation between either SI or SG and adiponectin protein or mRNA levels. PPAR-γ mRNA abundance remained constant, whereas leptin and resistin mRNAs and plasma leptin declined and RXR-α mRNA abundance increased in both white and brown fat. Leptin mRNA abundance was closely correlated with SI (R2 = 0.91 and 0.87 for white and brown fat, respectively). Resistin mRNA abundance correlated inversely with SG (R2 = 0.99 and 0.84 for white and brown fat, respectively). These data indicate that changes in the expression of leptin are more closely correlated with the insulin resistance of fasting than with changes in other adipokines or RXR-α and PPAR-γ expression.Key words: insulin resistance, fasting, adipokines, resistin, leptin, adiponectin.

scholarly journals Adipogenesis and lipotoxicity: role of peroxisome proliferator-activated receptor γ (PPARγ) and PPARγcoactivator-1 (PGC1)

2007 ◽  
Vol 10 (10A) ◽  
pp. 1132-1137 ◽  
Author(s):  
Gema Medina-Gomez ◽  
Sarah Gray ◽  
Antonio Vidal-Puig
Keyword(s):  
Insulin Resistance ◽  
Fatty Acids ◽  
Adipose Tissue ◽  
Peroxisome Proliferator ◽  
Metabolic Complications ◽  
Peroxisome Proliferator Activated Receptor ◽  
Toxic Response ◽  
Increased Risk ◽  
And Function

AbstractObesity is characterised by an increase in the adipose deposits, resulting from an imbalance between food intake and energy expenditure. When expansion of the adipose tissue reaches its maximum limit, as in obesity, fat accumulates in non-adipose tissues such as liver, heart, muscle and pancreas, developing a toxic response known as lipotoxicity, a condition that promotes the development of insulin resistance and other metabolic complications. Thus, the lipotoxic state may contribute to the increased risk of insulin resistance, diabetes, fatty liver and cardiovascular complications associated with obesity.We are interested in studying adipose tissue, specifically how mechanisms of adipogenesis and remodelling of adipose tissue, in terms of size and function of the adipocytes, could be considered a strategy to increase the capacity for lipid storage and prevent lipotoxicity. The peroxisome proliferator-activated receptors (PPARs) are a family of transcription factors that regulate energy balance by promoting either energy deposition or energy dissipation. Under normal physiological conditions, PPARγ is mainly expressed in adipose tissue and regulates diverse functions such as the development of fat cells and their capacity to store lipids. The generation of PPARγ knockout mice, either tissue specific or isoform specific, has provided new models to study PPARγ’s role in adipose tissue differentiation and function and have highlighted the essential role of PPARγ in adipogenesis and lipogenesis.A second strategy to prevent lipotoxicity is to increase the capacity of tissues to oxidise fatty acids. PPARγcoactivator-1α is a coactivator of PPARγ that induces the expression of genes that promote the differentiation of preadipocytes to brown adipocytes. Recently, it has been implicated in increasing the oxidation of fatty acids via increasing mitochondrial capacity and function, making this co-factor a key candidate for the treatment of lipotoxicity.

scholarly journals Impact of Maternal Periconceptional Overnutrition on Fat Mass and Expression of Adipogenic and Lipogenic Genes in Visceral and Subcutaneous Fat Depots in the Postnatal Lamb

Endocrinology ◽  
2010 ◽  
Vol 151 (11) ◽  
pp. 5195-5205 ◽  
Author(s):  
L. Rattanatray ◽  
S. M. MacLaughlin ◽  
D. O. Kleemann ◽  
S. K. Walker ◽  
B. S. Muhlhausler ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Fat Mass ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Lipogenic Genes ◽  
Fat Depots ◽  
Adiponectin Mrna ◽  
Periconceptional Period ◽  
Total Fat ◽  
Maternal Overnutrition

Women entering pregnancy with a high body weight and fat mass have babies who are at increased risk of becoming overweight or obese in later life. We investigated whether maternal overnutrition in the periconceptional period results in an increased fat mass and expression of adipogenic and lipogenic genes in offspring and whether dietary restriction can reverse these changes. Nonpregnant donor ewes (n = 23) were assigned to one of four groups: control-control fed at 100% maintenance energy requirements (MER) for at least 5 months, control-restricted fed 100% MER for 4 months and 70% MER for 1 month, high-high (HH) fed ad libitum (170–190% MER) for 5 months, or high-restricted (HR) fed ad libitum for 4 months and 70% MER for 1 month. Single embryos were transferred to nonobese recipient ewes, and lamb fat depots were weighed at 4 months. Peroxisome proliferator-activated receptor-γ, glyceraldehyde-3-phosphate dehydrogenase, lipoprotein lipase, leptin, and adiponectin mRNA expression was measured in the lamb fat depots. Total fat mass was higher in female lambs in the HH but not HR group than controls. There was a relationship between donor ewe weight and total fat mass and G3PDH mRNA expression in perirenal fat in female lambs. There was no effect of periconceptional nutritional treatment on peroxisome proliferator-activated receptor-γ, glyceraldehyde-3-phosphate dehydrogenase, lipoprotein lipase, leptin, and adiponectin mRNA expression in any fat depot. Thus, exposure to maternal overnutrition in the periconceptional period alone results in an increased body fat mass in the offspring and that a short period of dietary restriction can reverse this effect.

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