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

Androgen excess in women with polycystic ovary syndrome (PCOS) may be ovarian and/or adrenal in origin, and one proposed contributing mechanism is altered cortisol metabolism. Increased peripheral metabolism of cortisol may occur by enhanced inactivation of cortisol by 5alpha-reductase (5alpha-R) or impaired reactivation of cortisol from cortisone by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) resulting in decreased negative feedback suppression of ACTH secretion maintaining normal plasma cortisol concentrations at the expense of androgen excess. We have tested whether any enzyme dysregulation was related to circulating insulin or androgen concentrations in women with PCOS and have sought to clarify their relationship with obesity. First, to avoid obesity-related effects on cortisol metabolism, 18 lean women with PCOS were compared with 19 lean controls who were closely matched for body mass index (BMI). Second, the impact of obesity was studied in a cross-section of 42 PCOS women of a broad range of BMI. We measured 24-h urinary excretion of steroid metabolites by gas chromatography/mass spectrometry and fasting metabolic and hormone profiles. Urinary excretion of androgens [androsterone (P = 0.003), etiocholanolone (P = 0.02), and C19 steroid sulfates (P = 0.009)], cortisone metabolites [tetrahydrocortisone (THE) (P = 0.02), alpha-cortolone (P < 0.001), beta-cortol + beta-cortolone (P < 0.001), cortolones (P < 0.001), and E metabolites (P < 0.001)], and TCM (P = 0.002) were raised in lean PCOS subjects when compared with controls. A significantly higher 5alpha-tetrahydrocortisol (5alpha-THF)/5beta-THF ratio (P = 0.04) and a significantly lower alpha-THF + THF + alpha-cortol/THE + cortolones ratio (P = 0.01) were found in lean PCOS women compared with lean controls, indicating both enhanced 5alpha-R and reduced 11beta-HSD1 activities. A decreased THE/cortolones ratio (P = 0.03) was also found in lean PCOS women compared with lean controls, indicating increased 20 alpha/beta-HSD activity. In the group of 42 PCOS subjects, measures of 5alpha/5beta reduction were positively correlated with the homeostasis model insulin resistance index (HOMA-R): alpha-THF/THF and HOMA-R (r = 0.34; P = 0.03), androsterone/etiocholanolone and HOMA-R (r = 0.32; P = 0.04), and total 5alpha /total 5beta and HOMA-R (r = 0.37; P = 0.02). A positive correlation was also found between measures of 5alpha-R and BMI (r = 0.37; P = 0.02). No correlation was found between measures of 11beta-HSD1 activity and indices of insulin sensitivity or BMI. We have demonstrated that there is an increased production rate of cortisol and androgens as measured in vivo in lean PCOS women. Insulin seems to enhance 5alpha reduction of steroids in PCOS but was not associated with the elevated cortisol production rate. The changes in 5alpha-R, 11beta-HSD1, and 20alpha/beta-HSD enzyme activities observed in PCOS may contribute to the increased production rates of cortisol and androgens, supporting the concept of a widespread dysregulation of steroid metabolism. This dysregulation does not seem to be the primary cause of PCOS because no correlation was found between serum androgen levels or urinary excretion of androgens with measurements of either 5alpha-R or 11beta-HSD1 activities.
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PMID:Altered cortisol metabolism in polycystic ovary syndrome: insulin enhances 5alpha-reduction but not the elevated adrenal steroid production rates. 1467 Nov 89

Tissue-specific dysregulation of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) activity in obese humans and animals may be associated with obesity and the metabolic syndrome. We investigated the effect of inhibition of 11beta-HSD with glycyrrhetinic acid (GE), an effective 11beta-HSD inhibitor, on body weight regulation in obese Zucker rats, which have a defect in the leptin receptor gene. GE (280 mg/kg/d) was administered in drinking water to 8-week-old male Zucker rats for 14 weeks. GE had no effect on food intake or weight gain, and did not affect hepatic 11beta-HSD1 and renal 11beta-HSD2 mRNA levels in obese rats. In contrast, average daily food intake and body weight on week 14 were significantly reduced by GE in lean rats (both P <.0001). Hepatic 11beta-HSD1 and renal 11beta-HSD2 mRNA levels were also significantly decreased by GE in lean rats (both P <.05). GE had no significant effect on plasma corticosterone levels in obese rats but lowered them in lean rats (P <.05). Plasma leptin levels declined in both GE-treated obese and lean rats (both P <.01). In conclusion, long-term GE treatment decreased weight gain in lean Zucker rats but not in obese Zucker rats. These findings suggest that the differing responses of 11beta-HSD1 to GE in obese and lean Zucker rats are closely associated with the different weight-gain responses. Furthermore, the weight-lowering effect of GE may require intact leptin receptors.
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PMID:Different responsiveness in body weight and hepatic 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 mrna to 11beta-HSD inhibition by glycyrrhetinic acid treatment in obese and lean zucker rats. 1513 64

Sucrose- and fructose-enriched diets produce hepatic insulin resistance in rats independently of obesity. In humans, fructose infusion results in impaired insulin regulation of glucose production. The aim of the present study was to identify intrahepatic mediators of sucrose- and fructose-induced hepatic insulin resistance. In study 1, male rats were fed a control diet (STD, 68% of energy from corn starch, 12% from corn oil) or a sucrose-enriched diet (HSD, 68% sucrose, 12% corn oil) for 1, 2, or 5 wk. HSD produced hepatic insulin resistance at all time points. Hepatic protein tyrosine phosphatase 1B protein levels and activity were increased at 5 wk only, whereas c-jun NH(2)-terminal kinase (JNK) activity was increased at all time points. Normalization of JNK activity in hepatocytes isolated from HSD rats improved insulin-stimulated tyrosine phosphorylation of insulin receptor substrate (IRS) proteins and insulin suppression of glucose release. In study 2, male rats were provided STD for 1 wk and then were either fasted or fasted and refed either STD or HSD for 3 or 6 h. Rats refed HSD were characterized by increased hepatic JNK activity and phosphorylation of IRS1 on Ser(307) after 6 h only. In study 3, hyperglycemic, hyperinsulinemic pancreatic clamps were performed for 3 or 6 h in the presence or absence of low or high intraportal fructose infusions. High intraportal fructose infusions, which increased portal vein fructose concentration to approximately 1 mM, increased hepatic JNK activity and phosphorylation of IRS1 on Ser(307) at 6 h only. These data suggest that sucrose- and fructose-induced hepatic insulin resistance are mediated, in part, via activation of JNK activity. Thus high rates of fructose metabolism in the liver appear to acutely activate stress pathways.
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PMID:Hepatospecific effects of fructose on c-jun NH2-terminal kinase: implications for hepatic insulin resistance. 1519 36

Glucocorticoids are potent regulators of protein, fat, and carbohydrate metabolism. To determine if cortisol production occurs within the splanchnic bed in humans, 11 nondiabetic subjects were studied using the hepatic/leg catheterization method along with an infusion of [9,11,12,12-2H4] cortisol (D4-cortisol) as proposed by Andrews et al. In the fasting state, there was net release (P < 0.05) of cortisol from the splanchnic bed (6.1 +/- 2.6 microg/min) and net uptake (P < 0.05) by the leg (1.7 +/- 0.7 microg/min). This, along with cortisol production by other tissues (e.g., the adrenals), resulted in a total-body cortisol appearance rate of 18.1 +/- 1.9 microg/min. Fractional splanchnic D4-cortisol extraction averaged 12.9 +/- 1.3% (P < 0.001), splanchnic cortisol uptake 14.8 +/- 2.0 microg/min (P < 0.001), and splanchnic cortisol production 22.2 +/- 3.3 microg/min (P < 0.001). On the other hand, fractional leg D4-cortisol extraction averaged 5.6 +/- 1.8% (P < 0.02), leg cortisol uptake 2.3 +/- 0.7 microg/min (P < 0.01), and leg cortisol production 0.4 +/- 0.4 microg/min, which did not differ from zero. Because D4-cortisol loses a deuterium during conversion to [9,12,12-2H3] cortisone (D3-cortisone), which in turn generates [9,12,12(2)H3] cortisol (D3-cortisol) via 11-beta hydroxysteroid dehydrogenase (11beta-HSD) type 1, D3-cortisol production can be used as an index of 11beta-HSD type 1 activity. Net splanchnic D3-cortisol release (3.9 +/- 0.4 microg/min) and splanchnic D3-cortisol production (7.1 +/- 0.7 microg/min) occurred (P < 0.01) in all subjects. In contrast, there was minimal leg D3-cortisol production (0.04 +/- 0.01 microg/min), resulting in a strong correlation between splanchnic D3-cortisol production and total-body 3D-cortisol production in both the fasting state (r = 0.84; P < 0.02) and during an infusion of insulin (r = 0.97; P < 0.01). Thus, splanchnic production of cortisol occurs in nondiabetic humans at rates approximating that which occurs in the remainder of the body. These data support the possibility that alterations in splanchnic cortisol production contribute to visceral fat accumulation and the hepatic insulin resistance of obesity or type 2 diabetes.
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PMID:Splanchnic cortisol production occurs in humans: evidence for conversion of cortisone to cortisol via the 11-beta hydroxysteroid dehydrogenase (11beta-hsd) type 1 pathway. 1527 85

Two isozymes of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) interconvert active cortisol and inactive cortisone. 11 beta-HSD2 (renal) acts only as a dehydrogenase, converting cortisol to cortisone. 11 beta-HSD1 (liver) is a bi-directional enzyme in cell homogenates, whereas in intact cells it typically displays oxo-reductase activity, generating cortisol from cortisone. We recently established that cortisone reductase deficiency is a digenic disease requiring mutations in both the gene encoding 11 beta-HSD1 and in the gene for a novel enzyme located within the lumen of the endoplasmic reticulum (ER), hexose-6-phosphate dehydrogenase (H6PDH). This latter enzyme generates NADPH, the co-factor required for oxo-reductase activity. Therefore, we hypothesized that H6PDH expression may be an important determinant of 11 beta-HSD1 oxo-reductase activity. Transient transfection of chinese hamster ovary (CHO) cells with 11 beta-HSD1 resulted in the appearance of both oxo-reductase and dehydrogenase activities in intact cells. Co-transfection of 11 beta-HSD1 with H6PDH increased oxo-reductase activity whilst virtually eliminating dehydrogenase activity. In contrast, H6PDH had no effect on reaction direction of 11 beta-HSD2, nor did the cytosolic enzyme, glucose-6-phosphate dehydrogenase (G6PD) affect 11 beta-HSD1 oxo-reductase activity. Conversely in HEK 293 cells stably transfected with 11 beta-HSD1 cDNA, transfection of an H6PDH siRNA reduced 11 beta-HSD1 oxo-reductase activity whilst simultaneously increasing 11 beta-HSD1 dehydrogenase activity. In human omental preadipocytes obtained from 15 females of variable body mass index (BMI), H6PDH mRNA levels positively correlated with 11 beta-HSD1 oxo-reductase activity, independent of 11 beta-HSD1 mRNA levels. H6PDH expression increased 5.3-fold across adipocyte differentiation (P < 0.05) and was associated with a switch from 11 beta-HSD1 dehydrogenase to oxo-reductase activity. In conclusion, H6PDH is a crucial determinant of 11 beta-HSD1 oxo-reductase activity in intact cells. Through its interaction with 11 beta-HSD1, H6PDH may represent a novel target in the pathogenesis and treatment of obesity.
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PMID:Hexose-6-phosphate dehydrogenase confers oxo-reductase activity upon 11 beta-hydroxysteroid dehydrogenase type 1. 1595 39

A number of epidemiological studies worldwide have demonstrated a relationship between poor early growth and an increased susceptibility to insulin resistance, visceral obesity, type 2 diabetes and other features of the metabolic syndrome in adulthood. However, the mechanistic basis of this relationship and the relative roles of genes and the environment remain a subject of debate. The 'thrifty phenotype' hypothesis proposes that poor fetal nutrition leads to programming of metabolism and an adult phenotype that is adapted to poor but not plentiful nutrition. The maternal reduced-protein rat model has been used to examine the importance of the maternal environment in determining susceptibility to adult disease. Pregnant and lactating rat dams are fed a diet containing 80 g protein/kg as compared with 200 g protein/kg, which leads to growth restriction in utero. Offspring of low-protein dams have increased susceptibility to diabetes, insulin resistance and hypertension when fed a palatable high-fat diet that promotes obesity. Administration of leptin during pregnancy and lactation to these protein-restricted dams produces offspring that have increased metabolic rate and do not become obese or insulin resistant when fed on a high-fat diet. Increased glucocorticoid exposure, particularly during late gestation, has been linked with insulin resistance in adulthood. High levels of fetal glucocorticoids may result from a decreased activity of placental 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 2, which normally protects the fetus from high maternal glucocorticoid levels. Leptin administration to protein-restricted dams inhibits the suppression of 11beta-HSD-2 and may be one mechanism by which the metabolic syndrome is prevented.
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PMID:Fetal origins of insulin resistance and obesity. 1596 Aug 59

The purpose of this study was to test whether the melanocortin-4 receptor (MC4R) is critical in the development of hypertension associated with obesity and its metabolic disorders. MC4R-deficient homozygous (-/-) and heterozygous (+/-) and wild-type (WT) C57BL/6J mice 17 to 19 weeks old (n=5 to 7 per group) were implanted with telemetry devices for monitoring 24-hour mean arterial pressure (MAP) and heart rate (HR). After 3-day stable control measurements on normal-salt diet (NSD; 0.4% NaCl), mice received a high-salt diet (HSD; 4% NaCl) for 7 days, followed by 3-day recovery on NSD. MC4R (-/-) mice were severely obese compared with MC4R (+/-) and WT mice (body weight 48+/-1.5 versus 31+/-0.6 and 30+/-0.5 g respectively). On NSD, MAP was similar in all groups of mice (MC4R (-/-) 110+/-3 mm Hg; MC4R (+/-) 109+/-2 mm Hg; WT 114+/-2 mm Hg), and HR in MC4R (-/-) was lower than in WT (604+/-5 versus 645+/-9 bpm; P<0.05) but not different from MC4R (+/-) (625+/-13 bpm) mice. HSD did not significantly alter MAP or HR in any of the groups. Epididymal and retroperitoneal fat weights and plasma leptin levels were several-fold greater in MC4R (-/-) compared with MC4R (+/-) and WT mice. Plasma insulin and glucose levels were also significantly greater in MC4R (-/-) than in MC4R (+/-) and WT mice. These data suggest that despite obesity, visceral adiposity, hyperleptinemia, and hyperinsulinemia, MC4R (-/-) mice are neither hypertensive nor salt sensitive, indicating that a functional MC4R may be necessary for the development of hypertension associated with obesity and its metabolic abnormalities.
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PMID:Melanocortin-4 receptor-deficient mice are not hypertensive or salt-sensitive despite obesity, hyperinsulinemia, and hyperleptinemia. 1602 45

Our purpose was to investigate the effects of electroacupuncture (EA) therapy on body weight and on levels of serum insulin, c-peptide and glucose in obese women. 52 healthy women were included in this study and were allocated into three groups: 1) Placebo EA group (n = 15; mean age = 41.8 +/- 4.6 and mean body mass index {BMI} = 33.2 +/- 3.5); 2) EA group (n = 20; mean age = 42.1 +/- 4.4 and BMI = 35.9 +/- 3.6) and 3) Diet restriction group (n = 20; mean age = 42.9 +/- 4.3 and BMI = 34.7 +/- 2.7). EA was applied to the ear points Hunger and Shen Men on alternating days and to the body points LI 4, LI 11, St 36 and St 44 once a day for 30 minutes over 20 days. Diet restriction that entailed a 1450 kilocalorie (kcal) diet program was applied to the three groups for 20 days. An increase in weight loss was observed when weight loss in the EA group (p < 0.000) was compared to that in the diet restricted and placebo EA groups using the Tukey HSD test. There were increases in the serum insulin (p < 0.001) and c-peptide levels (p < 0.000) in the women treated with EA compared to those in the women treated with the placebo EA and diet restriction groups. A decrease was observed in the glucose levels (p < 0.01) in both the EA and diet restriction groups compared to those in the placebo EA group. Our results suggest that EA therapy is an effective method in treating obesity. EA therapy also helps serum glucose levels to decrease through the increase of serum insulin and c-peptide levels.
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PMID:Changes in levels of serum insulin, C-Peptide and glucose after electroacupuncture and diet therapy in obese women. 1671 Aug 86

Similarities between the metabolic syndrome and Cushing's syndrome, and reversibility of the features of Cushing's syndrome, suggest that cortisol may contribute to the pathophysiology of both conditions and that reducing cortisol action may provide a novel therapeutic approach in the metabolic syndrome. There is substantial evidence that circulating cortisol concentrations are higher in people with hypertension and glucose intolerance. The basis for this activation of the hypothalamic-pituitary-adrenal axis remains uncertain, but it may be attributable to 'programming' effects of events in early life, since it is associated with low birth weight. In obese people, intracellular cortisol levels within adipose tissue are further amplified by increased local regeneration of cortisol by the enzyme 11beta-HSD type 1. In mice, transgenic manipulations of 11beta-HSD1 have potent effects on obesity and associated features of the metabolic syndrome. Promising preclinical data suggest that novel 11beta-HSD1 inhibitors will have a role in lowering intracellular cortisol levels as a treatment for the metabolic syndrome. In addition to their metabolic effects, glucocorticoids act in the blood vessel wall. Pharmacoepidemiological studies suggest that glucocorticoid excess is an independent risk factor for cardiovascular disease. Recent data suggest that 11beta-HSD1 within the blood vessel wall influences vascular remodelling and angiogenesis, for example in the myocardium following coronary artery occlusion. Thus, glucocorticoid signalling provides a potentially tractable system to influence both risk factors for, and the outcome of, Type 2 diabetes and cardiovascular disease.
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PMID:Cortisol--cause and cure for metabolic syndrome? 1711 76

In a cross-sectional study of 2,802 perimenopausal caucasian women, carriage of at least one mutated allele of the 17-alpha-hydroxysteroid dehydrogenase type 1 (17-alpha HSD) vlV A-->C single nucleotide polymorphism (SNP) was associated with a significantly increased body mass index (mean 24.3 +/- 4.4 kg/m(2) vs. 23.5 +/- 4.2 kg/m(2); P<.001), and obesity was more frequent among mutant allele carriers (P=.06; odds ratio 1.38; 95% confidence interval 0.97-1.95), providing evidence of 17-alpha HSD as a candidate gene of perimenopausal obesity.
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PMID:An estrogen metabolism-related polymorphism of the 17-alpha HSD gene is associated with perimenopausal body mass index. 1720 97


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