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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Obesity is characterized by adipocyte hypertrophy and macrophage accumulation in adipose tissue. Monocyte chemoattractant protein-1 (MCP-1) plays a role in macrophage recruitment into adipose tissue. However, other adipocyte-derived factors, e.g., hyaluronan and serum amyloid A (SAA), can facilitate monocyte adhesion and chemotaxis, respectively. The objective was to test the potential involvement of these factors in macrophage recruitment. Differentiated 3T3-L1 adipocytes made hypertrophic by growth in high glucose conditions were used to study SAA and hyaluronan regulation in vitro. Two mouse models of obesity were used to study their expression in vivo. Nuclear factor-kappaB was upregulated and peroxisome proliferator-activated receptor (PPAR)gamma was downregulated in hypertrophic 3T3-L1 cells, with increased expression of SAA3 and increased hyaluronan production. Rosiglitazone, a PPARgamma agonist, reversed these changes. Hypertrophic adipocytes demonstrated overexpression of SAA3 and hyaluronan synthase 2 in vitro and in vivo in diet-induced and genetic obesity. SAA and hyaluronan existed as part of a complex matrix that increased the adhesion and retention of monocytes. This complex, purified by binding to a biotinylated hyaluronan binding protein affinity column, also showed monocyte chemotactic activity, which was dependent on the presence of SAA3 and hyaluronan but independent of MCP-1. We hypothesize that adipocyte hypertrophy leads to increased production of SAA and hyaluronan, which act in concert to recruit and retain monocytes, thereby leading to local inflammation in adipose tissue.
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PMID:Adipocyte-derived serum amyloid A3 and hyaluronan play a role in monocyte recruitment and adhesion. 1756 62

Peroxisome proliferator-activated receptor-gamma (PPARgamma) regulates adipocyte genes involved in adipogenesis and lipid metabolism and is the molecular target for thiazolidinedione (TZD) antidiabetic agents. Adipose triglyceride lipase (ATGL) is a recently described triglyceride-specific lipase that is induced during adipogenesis and remains highly expressed in mature adipocytes. This study evaluates the ability of PPARgamma to directly regulate ATGL expression in adipocytes in vitro and in vivo. In fully differentiated 3T3-L1 adipocytes, ATGL mRNA and protein are increased by TZD and non-TZD PPARgamma agonists in a dose- and time-dependent manner. Rosiglitazone-mediated induction of ATGL mRNA is rapid and is not inhibited by the protein synthesis inhibitor cycloheximide, indicating that intervening protein synthesis is not required for this effect. Rosiglitazone-mediated induction of ATGL mRNA and protein is inhibited by the PPARgamma-specific antagonist GW-9662 and is also significantly reduced following siRNA-mediated knockdown of PPARgamma, supporting the direct transcriptional regulation of ATGL by PPARgamma. In vivo, ATGL mRNA and protein are increased by rosiglitazone treatment in white and brown adipose tissue of mice with and without obesity due to high-fat diet or leptin deficiency. Thus, PPARgamma positively regulates ATGL mRNA and protein expression in mature adipocytes in vitro and in adipose tissue in vivo, suggesting a role for ATGL in mediating PPARgamma's effects on lipid metabolism.
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PMID:PPARgamma regulates adipose triglyceride lipase in adipocytes in vitro and in vivo. 1784 38

Obese mice that lack leptin receptor (db (-) /db (-)) have been shown to have innate bronchial hyperresponsiveness (BHR). It has been proposed that the obesity-mediated BHR may involve a combination of increased leptin and reduced systemic adiponectin levels. The aim of this study was to determine if obesity modifies the airway concentration of leptin and adiponectin and whether treatment with a synthetic peroxisome proliferator-activated receptor gamma (PPARgamma) ligand can reduce airway leptin and increase airway adiponectin. In this study, obese, leptin receptor-deficient (db (-) /db (-)), or lean (db ( + ) /db (-)) mice were treated with rosiglitazone (3 mg/kg/day) or vehicle by gavage daily for 1 week. Bronchioalveolar lavage (BAL) was subsequently performed to determine levels of leptin, adiponectin, and inflammatory cytokines. Treatment with rosiglitazone increased BAL adiponectin levels in lean (p = 0.04) and to a lesser extent in obese mice (p = 0.07). Rosiglitazone treatment lowered leptin levels in lean mice, but increased leptin levels in BAL fluid of obese mice (p < 0.01). The BAL levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) were lower in the lean rosiglitazone-treated group compared with the obese vehicle-treated group and lower in the obese rosiglitazone-treated group compared with the obese vehicle-treated group. These results demonstrate that obesity is associated with alterations in adipokine and cytokine levels in the airways that can be modulated by treatment with roziglitazone.
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PMID:The peroxisome proliferator activated receptor gamma (PPARgamma) ligand rosiglitazone modulates bronchoalveolar lavage levels of leptin, adiponectin, and inflammatory cytokines in lean and obese mice. 1790 95

The growing prevalence of Type 2 diabetes with its high morbidity and excess mortality is imposing a heavy burden on healthcare systems. Because of the magnitude of the problem, obviating diabetes has been a long-standing dream. In the last decade, a number of intervention strategies have been shown to be effective for the prevention of diabetes in high-risk populations with prediabetes. Seven studies have now confirmed that lifestyle modifications, including weight-reducing diets and exercise programs, are very effective in precluding or delaying Type 2 diabetes in high-risk populations with impaired glucose tolerance (IGT). Two major trials are the Diabetes Prevention Study (n = 522) from Finland and the Diabetes Prevention Program (n = 3234) from the US. Both studies have shown that intensive lifestyle intervention could reduce the progression of IGT to diabetes by 58%. Furthermore, four currently-available drugs have been established as being effective in preventing diabetes in subjects with prediabetes. The Diabetes Prevention Program revealed that metformin 850 mg b.i.d. reduced the risk of diabetes by 31%. The STOP-NIDDM (Study To Prevent Non-Insulin-Dependent Diabetes Mellitus) trial (n = 1429) showed that acarbose 100 mg t.i.d. with meals decreased the incidence of diabetes by 36% when the diagnosis was based on 2 oral glucose tolerance tests. The XENDOS (Xenical in the Prevention of Diabetes in Obese Subjects) study examined the use of orlistat, an antiobesity drug, as an adjunct to an intensive lifestyle modification program in obese non-diabetic subjects. Orlistat treatment resulted in a 37% decline in the development of diabetes. More recently, the DREAM (Diabetes Reduction Assessment with Ramipril and Rosiglitazone Medication) study (n = 5269) demonstrated that rosiglitazone at 8 mg once/day in subjects with prediabetes (IGT and/or impaired fasting glucose) was effective in reducing the risk of diabetes by 60%. It can be concluded that Type 2 diabetes can be prevented or delayed through lifestyle modifications and/or pharmacologic interventions. This is a fact.
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PMID:Prevention of Type 2 diabetes: fact or fiction? 1803 59

Obesity and its physiological consequences are increasingly prevalent among women of reproductive age and are associated with infertility. To investigate, female mice were fed a high-fat diet until the onset of insulin resistance, followed by assessments of ovarian gene expression, ovulation, fertilization, and oocyte developmental competence. We report defects to ovarian function associated with diet-induced obesity (DIO) that result in poor oocyte quality, subsequently reduced blastocyst survival rates, and abnormal embryonic cellular differentiation. To identify critical cellular mediators of ovarian responses to obesity induced insulin resistance, DIO females were treated for 4 d before mating with an insulin-sensitizing pharmaceutical: glucose and lipid-lowering AMP kinase activator, 5-aminoimidazole 4-carboxamide-riboside, 30 mg/kg.d; sodium salicylate, IkappaK inhibitor that reverses insulin resistance, 50 mg/kg.d; or peroxisome proliferator activated receptor-gamma agonist rosiglitazone, 10 mg/kg.d. 5-aminoimidazole 4-carboxamide-riboside or sodium salicylate treatment did not have significant effects on the reproductive parameters examined. However, embryonic development to the blastocyst stage was significantly improved when DIO mice were treated with rosiglitazone, effectively repairing development rates. Rosiglitazone also normalized DIO-associated abnormal blastomere allocation to the inner cell mass. Such improvements to oocyte quality were coupled with weight loss, improved glucose metabolism, and changes in ovarian mRNA expression of peroxisome proliferator activated receptor-regulated genes, Cd36, Scarb1, and Fabp4 cholesterol transporters. These studies demonstrate that peri-conception treatment with select insulin-sensitizing pharmaceuticals can directly influence ovarian functions and ultimately exert positive effects on oocyte developmental competence. Improved blastocyst quality in obese females treated with rosiglitazone before mating indicates that peroxisome proliferator activated receptor-gamma is a key target for metabolic regulation of ovarian function and oocyte quality.
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PMID:Peroxisome proliferator-activated receptor-gamma agonist rosiglitazone reverses the adverse effects of diet-induced obesity on oocyte quality. 1827 52

Wersternized diet, containing high fat diet intake combined with high consumption of softdrinks, is accused with the emerge of modern epidemic obesity and diabesity. Therefore, we aimed to study the effect of this diet combination on the homeostasis of glucose, lipids, and some adipohormones in rats and to simulate the metabolic perturbations induced by the unhealthy Westernized diet intake, leading to the development of type 2 diabetes. To achieve this, we divided male Wistar rats (80-120 g) into two main groups: the first was fed commercial normal fat diet and the second received an in-house-prepared high-fat diet (HFD), combined with fructose in drinking water for a period of 6 weeks, followed by a subdiabetogenic dose of streptozotocin (STZ) (35 mg/kg) to produce frank hyperglycemia. The effect of this diet alone or after 2 weeks of treatment with rosiglitazone or glimepiride on glucose homeostasis, lipid profile, and levels of resistin and leptin was studied. The HFD/fructose/STZ diet elevated fasting plasma glucose, fructosamine, insulin, and homeostasis model assessment (HOMA) index, as well as serum triglycerides (TGs), total cholesterol (TC), and low-density lipoprotein cholesterol, with a decrease in high-density lipoprotein cholesterol. Hepatic TG and TC levels, as well as serum activities of aspartate transaminase (AST), alanine transaminase (ALT), and lactate dehydrogenase (LDH), were increased, suggesting a diet-induced hepatic steatosis, beside the increased levels of serum resistin and leptin. Rosiglitazone corrected the altered parameters measured, except for liver TGs; similarly, glimepiride reinstated the inverted parameters but raised insulin level and, consequently, the HOMA index. These results show that this diet could be used to induce an effect that mimics human type 2 diabetes with its metabolic disturbances and is suitable for screening the antidiabetic agents used for management of this disease.
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PMID:Westernized-like-diet-fed rats: effect on glucose homeostasis, lipid profile, and adipocyte hormones and their modulation by rosiglitazone and glimepiride. 1840 27

Obesity is associated with infiltration of macrophages into adipose tissue. Adipose macrophages may contribute to an elevated inflammatory status by secreting a variety of proinflammatory mediators, including tumor necrosis factor alpha and interleukin-6 (IL-6). Recent data suggest that during diet-induced obesity the phenotype of adipose-resident macrophages changes from alternatively activated macrophages toward a more classical and pro-inflammatory phenotype. Here, we explore the effect of peroxisome proliferator-activated receptor gamma activation on obesity-induced inflammation in 129SV mice fed a high fat diet for 20 weeks. High fat feeding increased bodyweight gain, adipose tissue mass, and liver triglycerides. Rosiglitazone treatment further increased adipose mass, reduced liver triglycerides, and changed adipose tissue morphology toward smaller adipocytes. Surprisingly, rosiglitazone markedly increased the number of macrophages in adipose tissue, as shown by immunohistochemical analysis and quantification of macrophage marker genes CD68 and F4/80+. In adipose tissue, markers for classically activated macrophages including IL-18 were down-regulated, whereas markers characteristic for alternatively activated macrophages (arginase 1, IL-10) were up-regulated by rosiglitazone. Importantly, conditioned media from rosiglitazone-treated alternatively activated macrophages neutralized the inhibitory effect of macrophages on 3T3-L1 adipocyte differentiation, suggesting that alternatively activated macrophages may be involved in mediating the effects of rosiglitazone on adipose tissue morphology and mass. Our results suggest that short term rosiglitazone treatment increases infiltration of alternatively activated macrophages in adipose tissue. The alternatively activated macrophages might play a role in peroxisome proliferator-activated receptor gamma-dependent expansion and remodeling of adipose tissue.
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PMID:Peroxisome proliferator-activated receptor gamma activation promotes infiltration of alternatively activated macrophages into adipose tissue. 1854 27

The acyl-CoA dehydrogenases (ACADs), which catalyze the rate-limiting step in the mitochondrial beta-oxidation spiral, were investigated in white adipose tissue (WAT) of C57Bl/6 mice treated with 10 mg/kg/day rosiglitazone. Rosiglitazone was also administered to PPAR-alpha knockout mice. ACAD abundance and activity were determined using western blotting and an ACAD enzyme activity assay. Rosiglitazone increased ACAD activity in both epididymal and inguinal WAT but not in brown adipose tissue, liver, or muscle. Given the known function of PPAR-alpha in regulating the expression of ACAD genes in liver, it was hypothesized that PPAR-alpha may be involved in upregulating the ACADs during rosiglitazone-mediated adipose tissue remodeling. However, the effect of rosiglitazone on adipose tissue ACAD activity was the same in wild-type and PPAR-alpha knockout mice. In conclusion, rosiglitazone increases expression and activity of ACAD enzymes in WAT independently of PPAR-alpha.
Obesity (Silver Spring) 2009 Jan
PMID:The regulation of acyl-CoA dehydrogenases in adipose tissue by rosiglitazone. 1894 67

Postprandial lipemia has emerged as an independent risk factor for coronary artery disease. In this systematic review we examined the effect of the medications used for the management of diabetes, obesity and dyslipidemia on postprandial lipemia. It should be mentioned that no standardization exists for a test meal and for the duration of observation postprandially to allow for direct comparisons between the published studies. Type 2 diabetes mellitus and insulin resistance are associated with enhanced postprandial lipemia. Insulin is effective in reducing both fasting and post prandial total triglyceride levels as well as triglycerides contained in the triglyceride-rich lipoprotein sub-fractions. Additionally, the newer rapid-acting insulin analogues seem to be more effective in the reduction of postprandial lipemia than the short-acting human insulins. Acarbose ameliorates postprandial lipemia and reduces the atherogenic chylomicron and very low density lipoprotein remnants. Metformin reduces both fasting and postprandial triglyceridemia, fasting and post-prandial free fatty acids and may increase the concentrations of the high density lipoprotein cholesterol. Sulfonylureas reduce fasting and postprandial triglyceride levels while data on the effect on high density lipoprotein levels are inconsistent. The effect of meglitinides on postprandial lipid metabolism is neutral. Rosiglitazone decreases fasting and postprandial free fatty acids but has no significant effect on fasting and postprandial triglycerides. Pioglitazone has additional beneficial effects on lipid metabolism because it reduces postprandial free fatty acids, fasting and postprandial triglycerides and increases high density lipoprotein cholesterol levels. Limited available data suggest that glucagon-like peptide-1 analogues and vildagliptin reduce postprandial lipemia through reduction of intestinally-derived triglycerides. No data exist on the effect of sitagliptin on postprandial lipemia. Orlistat improves postprandial lipemia by reducing the absorption of the dietary fat; no data exist on the effect of sibutramine and rimonabant on the metabolism of lipids in the postprandial state.
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PMID:The effects of medications used for the management of diabetes and obesity on postprandial lipid metabolism. 1899 2

An epidemic of metabolic diseases including type 2 diabetes and obesity is undermining the health of people living in industrialized societies. There is an urgent need to develop innovative therapeutics. The peroxisome proliferator-activated receptor gamma (PPARgamma) is one of the ligand-activated transcription factors in the nuclear hormone receptor superfamily and a pivotal regulator of glucose and lipid homeostasis. The discovery of PPARgamma as a target of multimodal insulin sensitizers, represented by thiazolidinediones (TZDs), has attracted remarkable scientific interest and had a great impact on the pharmaceutical industry. With the clinical success of the PPARgamma agonists, pioglitazone (Actos) and rosiglitazone (Avandia), development of novel and potent insulin-sensitizing agents with diverse clinical profiles has been accelerated. Currently, a number of PPARgamma agonists from different chemical classes and with varying pharmacological profiles are being developed. Despite quite a few obstacles to the development of PPAR-related drugs, PPARgamma-targeted agents still hold promise. There are new concepts and encouraging evidence emerging that suggest this class can yield improved anti-diabetic agents. This review covers the discovery of TZDs, provides an overview of PPARgamma including the significance of PPARgamma as a drug target, describes the current status of a wide variety of novel PPARgamma ligands including PPAR dual and pan agonists and selective PPARgamma modulators (SPPARgammaMs), and highlights new approaches for identifying agents targeting PPARgamma in the treatment of type 2 diabetes.
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PMID:Peroxisome proliferator-activated receptor gamma agonists as insulin sensitizers: from the discovery to recent progress. 1907 61


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