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

To determine if increased local production of glucocorticoids by the pancreatic islets might play a role in the spontaneous noninsulin-dependent diabetes mellitus of obesity, we compared islet 11beta-HSD-1 mRNA and activity in islets of obese prediabetic and diabetic Zucker Diabetic Fatty (ZDF) (fa/fa) rats and lean wild-type (+/+) controls. In diabetic rat islets, both mRNA and enzymatic activity of the enzyme were increased in proportion to the hyperglycemia. Troglitazone (TGZ) treatment, beginning at 6 weeks of age, prevented the hyperglycemia, the hyperlipidemia, and the increase in 11beta-HSD-1. To determine if the metabolic abnormalities had caused the 11beta-HSD-1 increase, prediabetic islets were cultured in high or low glucose or in 2:1 oleate:palmitate for 3 days. Neither nutrient enhanced the expression of 11beta-HSD-1. We conclude that 11beta-HSD-1 expression and activity are increased in islets of diabetic, but not prediabetic ZDF rats, and that TGZ prevents both the increase in 11beta-HSD-1 and the diabetes.
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PMID:Increased expression and activity of 11beta-HSD-1 in diabetic islets and prevention with troglitazone. 1469 32

The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) amplifies intracellular glucocorticoid action in vivo. 11beta-HSD-1 activity is increased in adipose tissues of obese humans and genetically obese rodents, providing a mechanistic basis for the similarities between metabolic disease arising from high circulating glucocorticoids (Cushing's syndrome) and idiopathic obesity/metabolic syndrome where plasma glucocorticoids are typically unaltered. Fat-specific overexpression of 11beta-HSD-1 produces a metabolic syndrome in mice, whereas 11beta-HSD-1 null mice resist high-fat diet (HF)-induced visceral obesity and its metabolic consequences. Here we compared the effects of chronic (18 wk) HF feeding on adipose 11beta-HSD-1 activity in strains of mice that are either resistant (A/J) or prone (C57BL/6J) to metabolic disease. 11beta-HSD-1 activity was highest in sc fat, followed by epididymal fat, with lowest activity in the mesenteric visceral depot of both strains. 11beta-HSD-1 activity was lower in white adipose tissues of A/J compared with C57BL/6J mice. Chronic HF feeding unexpectedly caused a down-regulation of 11beta-HSD-1 in adipose tissues of both strains, despite comparable adiposity. However, A/J mice down-regulated adipose 11beta-HSD-1 to a significantly lower level than C57BL/6J mice in white and thermogenic brown adipose tissues. We propose that a lower adipose 11beta-HSD-1 set point affords a metabolic protection to A/J mice. Adaptive down-regulation of adipose 11beta-HSD-1 in response to chronic HF represents a novel mechanism that may counteract metabolic disease.
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PMID:Down-regulation of adipose 11beta-hydroxysteroid dehydrogenase type 1 by high-fat feeding in mice: a potential adaptive mechanism counteracting metabolic disease. 1504 72

The metabolic syndrome (visceral obesity, insulin resistance, type 2 diabetes, and dyslipidemia) resembles Cushing's Syndrome, but without elevated circulating glucocorticoid levels. An emerging concept suggests that the aberrantly elevated levels of the intracellular glucocorticoid reamplifying enzyme 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD-1) found in adipose tissue of obese humans and rodents underlies the phenotypic similarities between idiopathic and "Cushingoid" obesity. Transgenic overexpression of 11 beta-HSD-1 in adipose tissue reproduces a metabolic syndrome in mice, whereas 11 beta-HSD-1 deficiency or inhibition has beneficial metabolic effects, at least on liver metabolism. Here we report novel protective effects of 11 beta-HSD-1 deficiency on adipose function, distribution, and gene expression in vivo in 11 beta-HSD-1 nullizygous (11 beta-HSD-1(-/-)) mice. 11 beta-HSD-1(-/-) mice expressed lower resistin and tumor necrosis factor-alpha, but higher peroxisome proliferator-activated receptor-gamma, adiponectin, and uncoupling protein-2 mRNA levels in adipose, indicating insulin sensitization. Isolated 11 beta-HSD-1(-/-) adipocytes exhibited higher basal and insulin-stimulated glucose uptake. 11 beta-HSD-1(-/-) mice also exhibited reduced visceral fat accumulation upon high-fat feeding. High-fat-fed 11 beta-HSD-1(-/-) mice rederived onto the C57BL/6J strain resisted diabetes and weight gain despite consuming more calories. These data provide the first in vivo evidence that adipose 11 beta-HSD-1 deficiency beneficially alters adipose tissue distribution and function, complementing the reported effects of hepatic 11 beta-HSD-1 deficiency or inhibition.
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PMID:Novel adipose tissue-mediated resistance to diet-induced visceral obesity in 11 beta-hydroxysteroid dehydrogenase type 1-deficient mice. 1504 7

Following extensive suprasellar operations for excision of hypothalamic tumors, some patients develop morbid obesity despite receiving replacement doses of glucocorticoids. Urine analysis of cortisol and cortisone metabolites show that 11-OH/11-oxo ratios are significantly higher in patients with hypothalamic obesity, indicating enhanced 11beta-HSD1 activity. This correlates with the visceral-to-subcutaneous fat ratio. The consequence of increased 11beta-HSD1 activity and a shift of the steroid inter-conversion towards cortisol may contribute to the effects of the latter in adipose tissue. The message from the hypothalamus to adipocyte 11beta-HSD-1 involves hormones, the sympathetic nervous system and cytokines. CRH and ACTH downregulate 11beta-HSD-1 activity and induce lipolysis. Tumor necrosis factor-alpha and interleukin-1beta upregulate 11beta-HSD-1 expression and activity, while enhancing lipolysis. The sympathetic nervous system exerts its effects through beta-adrenergic upregulation and alpha-adrenergic downregulation of 11beta-HSD-1 activity. Inhibition of 11beta-HSD-1 suppresses preadipocyte differentiation into mature adipocytes, and may provide a therapeutic tool.
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PMID:Hypothalamic regulation of adiposity: the role of 11beta-hydroxysteroid dehydrogenase type 1. 1524 25

11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) catalyzes the interconversion of inactive cortisone to active cortisol. Overexpression of 11beta-HSD-1 in murine adipose tissue results in glucocorticoid receptor (GR)alpha overexpression, central obesity, and insulin resistance. It is controversial whether 11beta-HSD-1 or GRalpha expression are increased in human adipose tissue in obesity. We studied effects of acquired obesity on 11beta-HSD-1 gene (real-time PCR) and protein (Western blotting) expression in sc adipose tissue in 17 monozygotic twin pairs aged 24-27 yr with a mean intrapair difference in body mass index (BMI) of 3.8 kg/m(2) (range 0.4-10.1 kg/m(2)). Intrapair correlations were calculated to study effects of acquired obesity on 11beta-HSD-1 expression. Western blot analysis of adipose tissue homogenates identified approximately 50- and approximately 68-kDa proteins specific for 11beta-HSD-1. Both structural forms correlated positively with 11beta-HSD-1 mRNA concentrations. Intrapair differences in 11beta-HSD-1 mRNA, and the 50- and 68-kDa proteins in sc adipose tissue correlated positively with those in BMI (kilograms per square meter) (r = 0.78 for 11beta-HSD-1 mRNA, P = 0.0002; r = 0.87 for the 11beta-HSD-1 50-kDa protein, P = 0.0003; and r = 0.62 for the 11beta-HSD-1 68-kDa protein, P = 0.033), total body fat (percent) (r = 0.65, P = 0.005; r = 0.83, P = 0.001; and r = 0.69, P = 0.013, respectively) and sc fat (cubed centimeters) (r = 0.66, P = 0.004; r = 0.94, P = 0.0001; and r = 0.71, P = 0.009, respectively). Furthermore, 11beta-HSD-1 mRNA and 50-kDa protein expression, but not 68-kDa protein expression, correlated positively with intrapair differences in intraabdominal fat mass (cubed centimeters) (r = 0.62, P = 0.008; r = 0.69, P = 0.013; r = 0.48, P = 0.112) and serum fasting insulin concentration (milliunits per liter) (r = 0.76, P = 0.0004; r = 0.60, P = 0.037; and r = 0.43, P = 0.160, respectively). Intrapair differences in GRalpha expression were significantly inversely correlated with those in BMI and total and sc fat mass. In conclusion, expression of 11beta-HSD-1 in sc adipose tissue is increased in human acquired obesity and is closely related to accumulation of sc and intraabdominal fat and features of insulin resistance.
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PMID:Overexpression of 11beta-hydroxysteroid dehydrogenase-1 in adipose tissue is associated with acquired obesity and features of insulin resistance: studies in young adult monozygotic twins. 1535 40

Altered peripheral glucocorticoid metabolism may be important in the pathogenesis of obesity in humans and animal models. Genetically obese Zucker rats, Lep/ob mice, and obese humans exhibit increased regeneration of active glucocorticoids selectively in adipose tissue by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) and increased glucocorticoid clearance by hepatic A-ring reductases. We have examined whether dietary obesity in rats induces the same changes in glucocorticoid metabolism. Male Wistar rats were weaned onto high-fat (HF; 45% kcal from fat) or control (10% fat) diets. After 3 wk, HF rats showed no differences in weight but were glucose intolerant, had lower 11beta-HSD-1 activity in liver (3.8 +/- 0.2 vs. 4.9 +/- 0.2 pmol product/min.mg protein; P <0.01), sc fat (0.03 +/- 0.01 vs. 0.09 +/- 0.01 pmol product/min.mg protein; P <0.01), and omental fat (0.02 +/- 0.001 vs. 0.03 +/- 0.003 pmol/ product/min.mg protein; P <0.05) and higher hepatic 5beta-reductase activity (0.26 +/- 0.05 vs. 0.10 +/- 0.007 pmol product/min.mg protein; P <0.05). After 20 wk, HF rats were obese, hyperglycemic, and hyperinsulinemic, but differences in 11beta-HSD-1 and 5beta-reductase activities were no longer apparent. Mature male rats given HF diets for 24 or 72 h showed increased hepatic 5beta-reductase activity and a trend for decreased sc adipose 11beta-HSD-1 activity. Dietary obesity is not accompanied by the changes in 11beta-HSD-1 and 5beta-reductase expression and activity observed in genetically obese rodents. Acute exposure to HF diet alters glucocorticoid metabolism, predicting lower hepatic and adipose intracellular glucocorticoid concentrations, which may be a key mechanism protecting against the metabolic complications of obesity.
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PMID:Reduced adipose glucocorticoid reactivation and increased hepatic glucocorticoid clearance as an early adaptation to high-fat feeding in Wistar rats. 1555 May 7

Glucocorticoids are important hormones in the regulation of metabolic homeostasis. We infused normal rats with dexamethasone given intracerebroventricularly (i.c.v.) for 3 days. This resulted in hyperphagia, hyperinsulinemia, and marked insulin resistance. Similar metabolic defects were observed following i.c.v. infusion of neuropeptide Y (NPY) in normal rats. As central dexamethasone infusion enhanced NPY content in the arcuate nucleus, it suggested that its metabolic effects are mediated by NPY. Moreover, due to the lack of effects observed in vagotomized animals, activation of the parasympathetic nervous system by central dexamethasone infusion is proposed. Glucocorticoid action is known to involve prereceptor metabolism by enzymes such as 11beta-HSD-1 that converts inactive into active glucocorticoids. Mice overexpressing 11beta-HSD-1 in adipose tissue were shown to be obese and insulin resistant. We recently observed that adipose tissue 11beta-HSD-1 mRNA expression is increased at the onset of high-fat diet-induced obesity and positively correlated with the degree of hyperglycemia. In human obesity, increased adipose tissue 11beta-HSD-1 expression and activity were also reported. Resistin is a new adipose tissue-secreted hormone shown to play a role in glucose homeostasis by increasing hepatic glucose production and inhibiting muscle and adipose tissue glucose utilization. We observed increased adipose tissue resistin expression in the early phase of high-fat diet-induced obesity as well as decreased resistin expression in response to leptin. A positive correlation between glycemia and adipose tissue resistin expression further suggested a role of this hormone in the development of insulin resistance. The melanocortin system is another important player in the regulation of energy balance. Peripheral administration of a melanocortin agonist decreased food intake and body weight and favored lipid oxidation, effects that were more marked in obese than in lean rats. It is proposed that both resistin and melanocortin agonists may influence adipose tissue 11beta-HSD-1, thereby decreasing or enhancing glucose metabolism.
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PMID:Role of glucocorticoids in the physiopathology of excessive fat deposition and insulin resistance. 1559 86

Glucocorticoids are important regulators of glucose, lipid and protein metabolism, acting mainly in the liver, adipose tissue and muscle. Chronic glucocorticoid excess is associated with clinical features, such as insulin resistance, visceral obesity, hypertension, and dyslipidemia, which also represent the classical hallmarks of the metabolic syndrome. Elevenbeta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1), a key intracellular enzyme which catalyses the conversion of inactive cortisone to active cortisol, has been implicated in the development of the metabolic syndrome. The shift of this reaction towards cortisol generation may lead to tissutal overexposure to glucocorticoids even with normal circulating cortisol levels. The most robust evidence in support of a pathogenetic role of this enzyme in the development of the metabolic syndrome has been reported in experimental animals, whereas results of human studies are less convincing with several case control and cross-sectional studies showing an association between with 11beta-HSD-1 setpoint and individual features of the metabolic syndrome. However, recent data suggest a tissue-specific rather than systemic alteration of this shuttle, with down-regulation in liver but up-regulation in adipose tissue and skeletal muscle of obese subjects. New techniques based on direct tissutal estimates of cortisol/cortisone ratios are clearly needed to precisely assess the role of enzyme in all target tissues. If confirmed, these results would prompt the development of selective and tissue-specific 11beta-HSD-1 inhibitors to decrease insulin resistance and treat the metabolic syndrome, thus contrasting the harmful effects of glucocorticoid excess in peripheral tissues.
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PMID:Tissue-specific dysregulation of 11beta-hydroxysteroid dehydrogenase type 1 and pathogenesis of the metabolic syndrome. 1576 49

The fact, that obesity is a prominent feature of hypercortisolism (Cushing's syndrome) has stimulated investigation on the possible existence of the reverse relationship, namely that hypercortisolism is a feature of obesity. We have reviewed half a century of literature on this question, and have found out the following: (1) Hypercortisolism can exist in two forms: systemic hypercortisolism, in which there is an overall bodily excess of cortisol, and tissue, or intracellular, hypercortisolism, in which there is increased intracellular concentration of cortisol without an overall bodily excess. (2) There are two parameters of systemic hypercortisolism: CPR and plasma cortisol concentration. Proper evaluation of the first parameter requires correction for the active metabolic mass, which is best performed by expressing CPR per gram of urinary creatinine. The second parameter can be confounded by the marked moment-to-moment fluctuations in plasma cortisol concentrations due to cortisol's episodic secretion. Proper evaluation requires measuring the 24-hour mean concentration. Of these two parameters of systemic cortisol status, the plasma concentration is the more critical and accurate. (3) Corrected CPR is normal in obese individuals, and 24-hour mean plasma cortisol concentrations are slightly but definitely subnormal. This combination of findings indicates diminished stimulability of the hypothalamic-pituitary-adrenal (HPA) axis, which normally regulates bodily cortisol status. This deduction is supported by empirical studies on HPA reactivity. (4) Tissue hypercortisolism, due to increased intracellular activity of 11beta-HSD-1, which catalyzes reduction of cortisone to cortisol, has been reported in obese mice and humans. The findings of various studies are not consistent, and whether the enzymatic overactivity is a cause or a result of obesity is still unclear.
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PMID:Obesity and cortisol status. 1595 76

Despite major advances in understanding monogenic causes of morbid obesity, the complex genetic and environmental etiology of idiopathic metabolic syndrome remains poorly understood. One hypothesis suggests that similarities between the metabolic disease of plasma glucocorticoid excess (Cushing's syndrome) and idiopathic metabolic syndrome results from increased glucocorticoid reamplification within adipose tissue by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1). Indeed, 11beta-HSD-1 is now a major therapeutic target. Because much supporting evidence for a role of adipose 11beta-HSD-1 comes from transgenic or obese rodents with single-gene mutations, we investigated whether the predicted traits of metabolic syndrome and glucocorticoid metabolism were coassociated in a unique polygenic model of obesity developed by long-term selection for divergent fat mass (Fat and Lean mice with 23 vs. 4% fat as body weight, respectively). Fat mice exhibited an insulin-resistant metabolic syndrome including fatty liver and hypertension. Unexpectedly, Fat mice had a marked intra-adipose (11beta-HSD-1) and plasma glucocorticoid deficiency but higher liver glucocorticoid action. Furthermore, metabolic disease was exacerbated only in Fat mice when challenged with exogenous glucocorticoids or a high-fat diet. Our data suggest that idiopathic metabolic syndrome might associate with such a novel pattern of glucocorticoid action and sensitivity in humans, with implications for tissue-specific therapeutic targeting of 11beta-HSD-1.
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PMID:A polygenic model of the metabolic syndrome with reduced circulating and intra-adipose glucocorticoid action. 1630 51


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