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

Obesity shortens life expectancy and is a risk factor for hypertension and Type 2 diabetes. When added to the standard chow of Sprague-Dawley or Otsuka Long-Evans Tokushima Fatty rats, alpha-lipoic acid (0.5% weight/weight) reduced body weight and food intake. Alpha-lipoic acid also increased whole-body energy expenditure. It exerts its effects by suppressing hypothalamic AMP-activated protein kinase. Long-term studies to determine whether these anti-obesity effects are maintained in animals are required before alpha-lipoic acid is considered for clinical trial in human obesity.
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PMID:Alpha-lipoic acid, an anti-obesity agent? 1556 20

As indicated by in vitro studies, both lipogenesis and lipolysis in adipocytes depend on the cellular ATP levels. Ectopic expression of mitochondrial uncoupling protein 1 (UCP1) in the white adipose tissue of the aP2-Ucp1 transgenic mice reduced obesity induced by genetic or dietary manipulations. Furthermore, respiratory uncoupling lowered the cellular energy charge in adipocytes, while the synthesis of fatty acids (FA) was inhibited and their oxidation increased. Importantly, the complex metabolic changes triggered by ectopic UCP1 were associated with the activation of AMP-activated protein kinase (AMPK), a metabolic master switch, in adipocytes. Effects of several typical treatments that reduce adiposity, such as administration of leptin, beta-adrenoceptor agonists, bezafibrate, dietary n-3 polyunsaturated FA or fasting, can be compared with a phenotype of the aP2-Ucp1 mice. These situations generally lead to the upregulation of mitochondrial UCPs and suppression of the cellular energy charge and FA synthesis in adipocytes. On the other hand, FA oxidation is increased. Moreover, it has been shown that AMPK in adipocytes can be activated by adipocyte-derived hormones leptin and adiponectin, and also by insulin-sensitizes thiazolidinediones. Thus, it is evident that metabolism of adipose tissue itself is important for the control of body fat content and that the cellular energy charge and AMPK are involved in the control of lipid metabolism in adipocytes. The reciprocal link between synthesis and oxidation of FA in adipocytes represents a prospective target for the new treatment strategies aimed at reducing obesity.
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PMID:Role of energy charge and AMP-activated protein kinase in adipocytes in the control of body fat stores. 1559 85

Skeletal muscle is a major mass peripheral tissue that accounts for approximately 40% of total body weight and 50% of energy expenditure and is a primary site of glucose disposal and fatty acid oxidation. Consequently, muscle has a significant role in insulin sensitivity, obesity, and the blood-lipid profile. Excessive caloric intake is sensed by the brain and induces beta-adrenergic receptor (beta-AR)-mediated adaptive thermogenesis. Beta-AR null mice develop severe obesity on a high fat diet. However, the target gene(s), target tissues(s), and molecular mechanism involved remain obscure. We observed that 30-60 min of beta-AR agonist (isoprenaline) treatment of C2C12 skeletal muscle cells strikingly activated (>100-fold) the expression of the mRNA encoding the nuclear hormone receptor, Nur77. In contrast, the expression of other nuclear receptors that regulate lipid and carbohydrate metabolism was not induced. Stable transfection of Nur77-specific small interfering RNAs (siNur77) into skeletal muscle cells repressed endogenous Nur77 mRNA expression. Moreover, we observed attenuation of gene and protein expression associated with the regulation of energy expenditure and lipid homeostasis, for example AMP-activated protein kinase gamma3, UCP3, CD36, adiponectin receptor 2, GLUT4, and caveolin-3. Attenuation of Nur77 expression resulted in decreased lipolysis. Finally, in concordance with the cell culture model, injection and electrotransfer of siNur77 into mouse tibialis cranialis muscle resulted in the repression of UCP3 mRNA expression. This study demonstrates regulatory cross-talk between the nuclear hormone receptor and beta-AR signaling pathways. Moreover, it suggests Nur77 modulates the expression of genes that are key regulators of skeletal muscle lipid and energy homeostasis. In conclusion, we speculate that Nur77 agonists would stimulate lipolysis and increase energy expenditure in skeletal muscle and suggest selective activators of Nur77 may have therapeutic utility in the treatment of obesity.
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PMID:Nur77 regulates lipolysis in skeletal muscle cells. Evidence for cross-talk between the beta-adrenergic and an orphan nuclear hormone receptor pathway. 1564 Jan 43

The occurrence of Type II (non-insulin-dependent) diabetes and obesity and their associated morbidities continue to increase and they are rapidly reaching epidemic proportions. AMPK (AMP-activated protein kinase) was initially thought of as an intracellular 'fuel gauge' responding to a decrease in the level of ATP by increasing energy production and decreasing energy utilization. Recent studies have shown that AMPK plays a role in controlling the whole body energy homoeostasis, including the regulation of plasma glucose levels, fatty acid oxidation and glycogen metabolism. In addition to its effects on the periphery, AMPK has been found to play a key role in the control of food intake through its regulation by hormones, including leptin, within the hypothalamus. The control of AMPK activity, therefore, provides an attractive target for therapeutic intervention in metabolic disorders such as obesity and Type II diabetes. Indeed, a number of physiological and pharmacological factors that are beneficial in these disorders have been shown to act, at least in part, through the activation of AMPK.
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PMID:AMP-activated protein kinase and the metabolic syndrome. 1578 7

Lifestyle interventions including exercise programs are cornerstones in the prevention of obesity-related diabetes. The AMP-activated protein kinase (AMPK) has been proposed to be responsible for many of the beneficial effects of exercise on glucose and lipid metabolism. The effects of long-term exercise training or 5-aminoimidazole-4-carboxamide-1-beta-d-riboruranoside (AICAR) treatment, both known AMPK activators, on the development of diabetes in male Zucker diabetic fatty (ZDF) rats were examined. Five-week-old, pre-diabetic ZDF rats underwent daily treadmill running or AICAR treatment over an 8-week period and were compared with an untreated group. In contrast to the untreated, both the exercised and AICAR-treated rats did not develop hyperglycemia during the intervention period. Whole-body insulin sensitivity, as assessed by a hyperinsulinemic-euglycemic clamp at the end of the intervention period, was markedly increased in the exercised and AICAR-treated animals compared with the untreated ZDF rats (P < 0.01). In addition, pancreatic beta-cell morphology was almost normal in the exercised and AICAR-treated animals, indicating that chronic AMPK activation in vivo might preserve beta-cell function. Our results suggest that activation of AMPK may represent a therapeutic approach to improve insulin action and prevent a decrease in beta-cell function associated with type 2 diabetes.
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PMID:Long-term AICAR administration and exercise prevents diabetes in ZDF rats. 1579 29

Although obesity is an epidemic threat to general health worldwide, an effective treatment has yet to be found. Insights into weight-regulatory pathways will accelerate the identification of new molecular targets for anti-obesity agents. 5'-AMP-activated protein kinase (AMPK) is an enzyme activated during low cellular energy charge. In peripheral tissues, the activation of AMPK influences various metabolic pathways, including glucose uptake, glycolysis, and fatty acid oxidation, all of which help to re-establish a normal cellular energy balance. AMPK is also present in the neurons of the hypothalamus, a critical center in the regulation of energy homeostasis. Recent studies from our group and others have shown that many factors (alpha-lipoic acid, leptin, insulin, ghrelin, glucose, 2-deoxyglucose, etc.) cause an alteration in hypothalamic AMPK activity that mediates effects on feeding behavior. Hypothalamic AMPK also appears to play a role in the central regulation of energy expenditure and peripheral glucose metabolism. These data indicate that hypothalamic AMPK is an important signaling molecule that integrates nutritional and hormonal signals and modulates feeding behavior and energy metabolism.
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PMID:Role of hypothalamic 5'-AMP-activated protein kinase in the regulation of food intake and energy homeostasis. 1580 19

Metabolic syndrome is thought to result from obesity and obesity-linked insulin resistance. Obesity in adulthood is characterized by adipocyte hypertrophy. Adipose tissue participates in the regulation of energy homeostasis as an important endocrine organ that secretes a number of biologically active "adipokines."Heterozygous peroxisome proliferator-activated receptor-gamma knockout mice were protected from high-fat diet induced obesity, adipocyte hypertrophy, and insulin resistance. Systematic gene profiling analysis of these mice revealed that adiponectin/Acrp30 was overexpressed. Functional analyses including generation of adiponectin transgenic or knockout mice have revealed that adiponectin serves as an insulin-sensitizing adipokine. In fact, obesity-linked down-regulation of adiponectin was a mechanism whereby obesity could cause insulin resistance and diabetes. Recently, we have cloned adiponectin receptors in the skeletal muscle (AdipoR1) and liver (AdipoR2), which appear to comprise a novel cell-surface receptor family. We showed that AdipoR1 and AdipoR2 serve as receptors for globular and full-length adiponectin and mediate increased AMP-activated protein kinase, peroxisome proliferator-activated receptor-alpha ligand activities, and glucose uptake and fatty-acid oxidation by adiponectin. Obesity decreased expression levels of AdipoR1/R2, thereby reducing adiponectin sensitivity, which finally leads to insulin resistance, the so-called "vicious cycle." Most recently, we showed that osmotin, which is a ligand for the yeast homolog of AdipoR (PHO36), activated AMPK via AdipoR in C2C12 myocytes. This may facilitate efficient development of adiponectin receptor agonists. Adiponectin receptor agonists and adiponectin sensitizers should serve as versatile treatment strategies for obesity-linked diseases such as diabetes and metabolic syndrome.
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PMID:Adiponectin and adiponectin receptors. 1589 98

Triglyceride accumulation in skeletal muscle contributes to insulin resistance in obesity. We recently showed that alpha-lipoic acid (ALA) reduces body weight and prevents the development of diabetes in diabetes-prone obese rats by reducing triglyceride accumulation in non-adipose tissues. AMP-activated protein kinase (AMPK) is a major regulator of cellular energy metabolism. We examined whether ALA lowers triglyceride accumulation in skeletal muscle by activating AMPK. Alpha2-AMPK activity was decreased in obese rats compared to control rats. Administration of ALA to obese rats increased insulin-stimulated glucose disposal in whole body and in skeletal muscle. ALA also increased fatty acid oxidation and activated AMPK in skeletal muscle. Adenovirus-mediated administration of dominant negative AMPK into skeletal muscle prevented the ALA-induced increases in fatty acid oxidation and insulin-stimulated glucose uptake. These results suggest that ALA-induced improvement of insulin sensitivity is mediated by activation of AMPK and reduced triglyceride accumulation in skeletal muscle.
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PMID:Alpha-lipoic acid increases insulin sensitivity by activating AMPK in skeletal muscle. 1591 51

Since obesity is becoming increasingly prevalent worldwide, much effort is being devoted to understanding its pathogenesis and treatment. In recent years, several candidate genes have been proposed as therapeutic targets. However, stearoyl-CoA desaturase 1 (SCD1) is of special significance, because it is the major gene target of leptin-a central mediator of energy homeostasis. There is evidence that SCD1 deficiency activates metabolic pathways that promote beta-oxidation and decrease lipogenesis in liver and skeletal muscles. One mechanism is via increased activation of AMP-activated protein kinase. SCD1 mutation results also in global changes in expression of genes involved in lipid metabolism. SCD1 deficient mice have increased energy expenditure, reduced body adiposity, and are resistant to diet-induced obesity. In this review, we examine data from our laboratory and others suggesting that SCD1 is an important component in the regulation of body metabolism.
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PMID:The role of stearoyl-CoA desaturase in the control of metabolism. 1594 55

Muscular exercise promotes glucose utilisation by the skeletal muscle, independently of insulin action, by activating the AMP-activated protein kinase (AMPK). This process is not altered in patients with obesity and/or type 2 diabetes, despite the presence of insulin resistance. Thus, exercise should play a key role in the management of type 2 diabetic patients. Regular physical activity enhances insulin sensitivity, improves glucose control and corrects some cardiovascular risk factors. This paper briefly presents some practical recommendations about physical activity in obese and/or type 2 diabetic patients.
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PMID:[Physical activity and type 2 diabetes]. 1603


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