11 beta-hydroxysteroid dehydrogenase type 1 in obesity and the metabolic syndrome

Upregulation of adipose 11-beta-hydroxysteroid dehydrogenase type 1 expression in ovariectomized rats is due to obesity rather than lack of estrogen

OBJECTIVE

Increased tissue activity of cortisol induced by the activation of inert cortisone to active cortisol through 11-beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) may play a role in the metabolic syndrome. We recently found that 11beta-HSD1 in subcutaneous adipose tissue (AT) was lower in lean women compared with lean men. Estrogen suppresses hepatic and renal 11beta-HSD1 in rats; hence we investigated the in vitro effect of estrogen on human and rat AT, and the in vivo effects on rat AT 11beta-HSD1 expression.

METHODS AND PROCEDURES

Wistar rats were divided into four groups of eight animals. One group was sham-operated (controls) and others were ovariectomized (OVX). One OVX group was left untreated (OVX-E), another (OVX+E) received estrogen treatment, and one received a hypo-caloric diet (OVX-E+D), matching the weight gain of the control group. AT from women undergoing liposuction or surgery and from killed male and female rats were incubated with estrogen alone or in the presence of IL-1beta. Gene expressions were determined by real-time reverse transcriptase PCR.

RESULTS

Ovariectomy resulted in a 280% increase in adipose 11beta-HSD1 expression P < 0.05). 11beta-HSD1 expression in the (OVX+E)-group was significantly reduced compared with the nonsubstituted group (P < 0.05). 11beta-HSD1 expression in the (OVX-E+D)-group was reduced significantly (P < 0.05) when compared with the level of the estrogen-substituted group. No significant differences between the control group, the (OVX+E)-group, and the (OVX-E+D)-group were found. In the in vitro studies, no direct effect of estrogen on adipose 11beta-HSD1 was found.

DISCUSSION

The upregulation of 11beta-HSD1 in ovariectomized rats was most likely due to changes in body composition rather than lack of estrogen.

Spironolactone effective hypertension in the elderly due to 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) impairment: contributory role of determining serum cortisol/cortisone ratio as a marker of 11beta-HSD2 activity

Two elderly patients with mineralocorticoid excess state due to 11 beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) impairment are described. Moreover, the role of the precursor-product ratios of the steroids reflecting 11beta-HSD2 activity was estimated in 5 patients, including 3 patients reported previously by us. Significant elevations of urinary cortisol/cortisone ratios were observed, whereas urinary tetrahydrocortisol (THF)+allo-THF/tetrahydrocortisone (THE) ratios were not elevated significantly. Furthermore, an even more distinct elevation of serum cortisol/cortisone ratio was evident in all instances of 5 patients, suggesting a significant clinical role of the serum cortisol/cortisone ratio in the diagnosis of 11beta-HSD2 impairment.

11 beta-hydroxysteroid dehydrogenase type 1 promotes differentiation of 3T3-L1 preadipocyte

AIM

To investigate the relationship between 11 beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), a potential link between obesity and type 2 diabetes, and preadipocyte differentiation.

METHODS

Mouse 11beta-HSD1 siRNA plasmids were transfected into 3T3-L1 preadipocytes (a cell line derived from mouse Swiss3T3 cells that were isolated from mouse embryo), for examination of the effect of targeted 11beta-HSD1 inhibition on differentiation of 3T3-L1 cells. Differentiation was stimulated with 3-isobutyl-1-methyxanthine, insulin, and dexamethasone. The transcription level of the genes was detected by real-time PCR.

RESULTS

Lipid accumulation was significantly inhibited in cells transfected with mouse 11beta-HSD1 siRNA compared with non-transfected 3T3-L1 cells. Fewer lipid droplets were detected in the transfected cells both prior to stimulation and after stimulation with differentiation-inducing reagents. The expression of adipocyte differentiation-associated markers such as lipoprotein lipase and fatty acid synthetase were downregulated in the transfected cells. Similarly, the expression of preadipocyte factor-1, an inhibitor of adipocyte differentiation, was downregulated upon stimulation of differentiation and had no changes in the transfected cells.

CONCLUSION

11 beta-HSD1 can promote preadipocyte differentiation. Based on this, we propose that 11 beta-HSD1 may be an important candidate mediator of obesity and obesity-induced insulin resistance.

11Beta-HSD type 1 expression in human adipose tissue: impact of gender, obesity, and fat localization

OBJECTIVE

Pre-receptor amplification of glucocorticoids is, in part, determined by the isoenzymes 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 and type 2, interconverting inert cortisone and active cortisol. Increased tissue activity of cortisol may play a part in features of the metabolic syndrome. Our objective was to compare 11beta-HSD1 gene expression in different fat depots (visceral, subcutaneous abdominal, and subcutaneous gluteal) in lean and obese men and women.

RESEARCH METHODS AND PROCEDURES

A cross-sectional study design was used for healthy patients undergoing minor abdominal surgery (lean men, 10), minor gynecological surgery (lean woman, 10), or gastric banding operations (obese men, 10; and obese women, 10). Gene expressions of 11beta-HSD1 in adipose tissue samples were determined by real-time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Lean women had lower 11beta-HSD1 gene expression in subcutaneous adipose tissue compared with men (62% lower, p < 0.01), whereas no significant difference was found between obese men and women. 11Beta-HSD1 mRNA in human adipose tissue was higher in obese subjects compared with lean subjects in both women and men and in both subcutaneous and visceral adipose tissue. No difference in mRNA expression of 11beta-HSD1 between visceral and subcutaneous adipose tissue or between subcutaneous adipose tissue from different depots was found.

CONCLUSIONS

11Beta-HSD1 in adipose tissue is increased in obesity in both women and men, and may contribute to the associated metabolic syndrome. As 11beta-HSD1 expression in lean women was found to be significantly lower than in lean males, the up-regulation associated with obesity may be relatively more devastating in women than in men, and may help explain the higher relative risk of cardiovascular disease in women suffering from the metabolic syndrome.

Cortisol levels and measures of body composition in middle-aged and older men

INTRODUCTION

Similarities in the symptomatic expressions of excess adiposity and hypercortisolaemic conditions suggest that elevated glucocorticoid exposure may influence the pathogenesis of obesity. Circulating cortisol levels are not typically elevated in obese subjects, but data from large prospective samples are rare. We undertook an analysis to determine both cross-sectional and longitudinal associations between body composition and serum cortisol concentrations in a randomly chosen group of 999 community-dwelling men, aged 40-79 years.

METHODS

Data were obtained from the two follow-up waves of the Massachusetts Male Ageing Study (T2: 1995-97; T3: 2002-04). Partial correlation and multivariate regression analyses were used to estimate cross-sectional (T2) and longitudinal associations between serum cortisol concentrations and a range of measures of subjects' body composition, including weight, body mass index (BMI), waist circumference (WC), waist-to-hip girth ratio (WHR), and percentage body fat (measured by bioelectrical impedance at T3); similar analyses were conducted to assess the association between change (T2 to T3) in serum cortisol and simultaneous change in body composition parameters.

RESULTS

We observed weak negative associations between cortisol concentrations and all body composition parameters, with the exception of percentage body fat. Longitudinal results demonstrated similar relationships but associations were of lesser magnitude. T2 cortisol concentrations were not associated with change in body composition over time, whereas T2 body size was positively associated with longitudinal changes in cortisol concentrations, providing limited evidence that weight change drives changes in cortisol concentrations, rather than vice versa. Results were unchanged when age and other covariate effects were controlled.

CONCLUSIONS

Circulating cortisol concentrations are somewhat lower in obese than in nonobese community-dwelling men. There is some evidence that excess adiposity presages increases in cortisol concentrations, rather than the reverse. However, this observation should be greeted with caution, as age-related weight loss - and not gain - was associated with simultaneous increases in serum cortisol concentrations.

Developmental programming of cardiovascular disorders: focus on hypertension

Increasing evidence suggests that adult cardiovascular disorders, e.g. hypertension, can be "programmed" in utero. The mechanisms that affect the developing fetus and lead to future cardiovascular disease are not fully established. This review addresses the possible involvement of maternal nutrition, sex steroids and other endocrine factors in the programming of hypertension in adulthood. Some possible mechanisms of subsequent development of hypertension in adulthood, such as elevated sympathetic and renin-angiotensin system activity, and failure of nephron development, also are discussed. Previous studies suggest that maternal undernutrition could be a major factor in fetal programming, but in light of the increased worldwide prevalence of obesity, maternal overnutrition is now receiving increased attention. Special emphasis is given here to this phenomenon. Obesity is associated with increased serum and tissue levels of proinflammatory cytokines, and loss of sensitivity to the adipokine leptin. It is postulated that this causes dysregulation of the hypothalamo-pituitary-adrenal axis, resulting in increased levels of circulating glucocorticoids. These factors could play a major role in programming, during the in utero period, of future hypertension in the offspring of obese mothers.

Developmental programming of obesity in mammals

Converging lines of evidence from epidemiological studies and animal models now indicate that the origins of obesity and related metabolic disorders lie not only in the interaction between genes and traditional adult risk factors, such as unbalanced diet and physical inactivity, but also in the interplay between genes and the embryonic, fetal and early postnatal environment. Whilst studies in man initially focused on the relationship between low birth weight and risk of adult obesity and metabolic syndrome, evidence is also growing to suggest that increased birth weight and/or adiposity at birth can also lead to increased risk for childhood and adult obesity. Hence, there appears to be increased risk of obesity at both ends of the birth weight spectrum. Animal models, including both under- and overnutrition in pregnancy and lactation lend increasing support to the developmental origins of obesity. This review focuses upon the influence of the maternal nutritional and hormonal environment in pregnancy in permanently programming appetite and energy expenditure and the hormonal, neuronal and autocrine mechanisms that contribute to the maintenance of energy balance in the offspring. We discuss the potential maternal programming 'vectors' and the molecular mechanisms that may lead to persistent pathophysiological changes resulting in subsequent disease. The perinatal environment, which appears to programme subsequent obesity, provides a potential therapeutic target, and work in this field will readily translate into improved interventional strategies to stem the growing epidemic of obesity, a disease which, once manifest, has proven particularly resistant to treatment.

Augmentation of 11beta-hydroxysteroid dehydrogenase type 1 in LPS-activated J774.1 macrophages--role of 11beta-HSD1 in pro-inflammatory properties in macrophages

Macrophage infiltration in obese adipose tissue provokes local inflammation and insulin resistance. Evidence has accumulated that activation of 11beta-HSD1 in adipocytes is critically involved in dysfunction of adipose tissue. However, the potential role of 11beta-HSD1 in macrophages still remains unclear. We here demonstrate that a murine macrophage cell line, J774.1 cells expressed 11beta-HSD1 mRNA and reductase activity, both of which were augmented by lipopolysaccharide (LPS)-induced cell activation. Three kinds of pharmacological inhibition of 11beta-HSD1 in LPS-treated macrophages significantly suppressed the expression and secretion of interleukin 1beta, tumor necrosis factor alpha or monocyte chemoattractant protein 1, thereby highlighting a novel role of 11beta-HSD1 in pro-inflammatory properties of activated macrophages.

Revisiting the metabolic syndrome

Metabolic syndrome (MS) refers to the clustering of cardiometabolic risk factors - including abdominal obesity, hyperglycaemia, dyslipidaemia and elevated blood pressure - that are thought to be linked to insulin resistance. MS is associated with increased risk of cardiovascular disease and type 2 diabetes. MS is common, affecting a quarter to a third of adults, and its prevalence is rising, in parallel with increasing obesity and population ageing. Operational definitions of MS have been proposed by the World Health Organization and the National Cholesterol Education Program. Recently, the International Diabetes Federation proposed a global definition that emphasised the importance of central adiposity. In cardiovascular risk assessment, MS encapsulates the contribution of non-traditional risk factors and provides a clinically useful framework for early identification of people at increased long-term risk. It should be used in conjunction with standard algorithms based on conventional risk factors, which better predict short-term risk. Management of MS should emphasise lifestyle interventions (eg, physical activity, healthy diet and weight reduction) to reduce long-term risk of cardiovascular disease and diabetes. Those at increased short-term risk should also have individual risk factors treated according to established guidelines.

11 beta-hydroxysteroid dehydrogenase type 1 induction in the arcuate nucleus by high-fat feeding: A novel constraint to hyperphagia?

11 beta-Hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) catalyzes regeneration of active intracellular glucocorticoids in fat, liver, and discrete brain regions. Although overexpression of 11 beta-HSD1 in adipose tissue causes hyperphagia and the metabolic syndrome, male 11 beta-HSD1 null (11 beta-HSD1-/-) mice resist metabolic disease on high-fat (HF) diet, but also show hyperphagia. This suggests 11 beta-HSD1 may influence the central actions of glucocorticoids on appetite and perhaps energy balance. We show that 11 beta-HSD1-/- mice express lower hypothalamic mRNA levels of the anorexigenic cocaine and amphetamine-regulated transcript and melanocortin-4 receptor, but higher levels of the orexigenic melanin-concentrating hormone mRNAs than controls (C57BL/6J) on a low-fat diet (11% fat). HF (58% fat) diet promoted transient ( approximately 8 wk) hyperphagia and decreased food efficiency in 11 beta-HSD1-/- mice and decreased melanocortin-4 receptor mRNA expression in control but not 11 beta-HSD1-/- mice. 11 beta-HSD1-/- mice showed a HF-mediated up-regulation of the orexigenic agouti-related peptide (AGRP) mRNA in the arcuate nucleus which paralleled the transient HF hyperphagia. Conversely, control mice showed a rapid (48 h) HF-mediated increase in arcuate 11 beta-HSD1 associated with subsequent down-regulation of AGRP. This regulatory pattern was unexpected because glucocorticoids increase AGRP, suggesting an alternate hyperphagic mechanism despite partial colocalization of 11 beta-HSD1 and AGRP in arcuate nucleus cells. One major alternate mechanism governing selective fat ingestion and the AGRP system is endogenous opioids. Treatment of HF-fed mice with the mu opioid agonist DAMGO recapitulated the HF-induced dissociation of arcuate AGRP expression between control and 11 beta-HSD1-/- mice, whereas the opioid antagonist naloxone given with HF induced a rise in arcuate AGRP and blocked HF-diet induction of 11 beta-HSD1. These data suggest that 11 beta-HSD1 in brain plays a role in the adaptive restraint of excess fat intake, in part by increasing inhibitory opioid tone on AGRP expression in the arcuate nucleus.

Glucocorticoid metabolism within superficial subcutaneous rather than visceral adipose tissue is associated with features of the metabolic syndrome in South African women

OBJECTIVE

Glucocorticoid hyperactivity in adipose tissue, due to up-regulation of local glucocorticoid reactivation by 11beta-hydroxysteroid dehydrogenase-1 (11HSD1) or of glucocorticoid receptors (GR), may underpin susceptibility to the metabolic syndrome. This hypothesis has been tested extensively in subcutaneous adipose tissue (SAT) but inadequately in visceral adipose tissue (VAT). The aim of the study was therefore to examine expression of 11HSD1, GRalpha and hexose-6-phosphate dehydrogenase (H6PDH), which supplies cofactor for 11HSD1, in abdominal adipose tissue compartments and to characterize their relation to metabolic syndrome parameters.

DESIGN AND SUBJECTS

A cross-sectional study including 26 premenopausal South African women.

MEASUREMENTS

Biopsies were taken for measurement of mRNA levels by real-time polymerase chain reaction (RT-PCR) and 11HSD1 activity from VAT, and deep and superficial SAT compartments during elective surgery. Prior to surgery, blood pressure, blood lipid profile, body composition [by dual X-ray absorptiometry (DEXA) scan], body fat distribution [by computed tomography (CT) scan], and glucose tolerance were determined.

RESULTS

11HSD1 activity (P < 0.01) was higher in VAT than SAT, but 11HSD1 and GRalpha mRNA levels were not statistically different between compartments. 11HSD1 mRNA levels in superficial SAT correlated with VAT volume (R = 0.57, P < 0.01), insulin sensitivity calculated from the oral glucose tolerance test (OGTT) (R = -0.52, P < 0.016) and blood pressure (R = 0.48, P < 0.016). Apart from a correlation between deep SAT 11HSD1 activity and blood pressure (R = 0.72, P < 0.01), glucocorticoid action in deep SAT and VAT depots was not significantly associated with any metabolic syndrome parameters.

CONCLUSION

Increased capacity for glucocorticoid regeneration in superficial SAT but not VAT is associated with visceral adiposity and other features of the metabolic syndrome in women.

Sex steroids and leptin regulate 11beta-hydroxysteroid dehydrogenase I and P450 aromatase expressions in human preadipocytes: Sex specificities

Adipose tissue is an important site of steroid hormone biosynthesis, as type I 11beta-hydroxysteroid dehydrogenase (HSD1), the enzyme responsible for the conversion of cortisone into cortisol and the P450 aromatase, the enzyme catalysing androgens aromatization into estrogens, are both expressed in human adipose tissue. In the present report, we have investigated the possibility that sex steroids and leptin could regulate these two enzymes in cultured preadipocytes from men and women intra-abdominal fat depots. In women preadipocytes, human recombinant leptin down-regulates HSD1 mRNA expression (-58%) and P450 aromatase activity (-26%). Conversely, leptin up-regulates the HSD1 (2.4-fold) and the P450 aromatase (1.6-fold) mRNA expression in men preadipocytes. In women preadipocytes, 17beta-estradiol strongly stimulates HSD1 mRNA expression (10-fold) and, in contrast, decreases by half the P450 aromatase expression. In men, 17beta-estradiol has no influence on HSD1 expression but up-regulates P450 aromatase mRNA expression (2.4-fold). Finally, androgens increase by a factor of 2.5-5 the mRNA expression of both enzymes in men. These findings suggest that sex steroids and leptin either increase or decrease local cortisol and estrogens productions in men or in women preadipocytes, respectively. They also indicate that steroid metabolism in adipose tissue is controlled by a coordinated regulation of P450 aromatase and HSD1 expressions. Finally, the important sex-specific differences described herein may also contribute to explain the sexual dimorphism of body fat distribution in humans.

Role of 11-beta-hydroxysteroid dehydrogenase type 1 in differentiation of 3T3-L1 cells and in rats with diet-induced obesity

AIM

To observe the roles of 11-beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) in in vitro preadipocyte differentiation and in rats with diet-induced obesity (DIO).

METHODS

Protein expression of 11beta-HSD1 in the process of 3T3-L1 cell differentiation and in various tissues of the rats were detected by Western blot analysis; expression of 11beta-HSD1 mRNA and glucocorticoid receptor (GR) and other marker genes of preadipocyte differentiation were detected by using real-time PCR.

RESULTS

Lipid droplets in 3T3-L1 cells accumulated and increased after stimulation. A dramatically elevated protein level of 11beta-HSD1, especially in the late stages of 3T3-L1 cell differentiation, was detected. The relative mRNA levels of 11beta-HSD1, GR and cell differentiation markers LPL, aP2, and FAS were upregulated, and Pref-1 was downregulated during the differentiation. In DIO rats, bodyweight, visceral adipose mass index and the protein expression of 11beta-HSD1 increased, especially in adipose tissue, brain and muscles. Serum insulin, triglyceride, total cholesterol and low-density lipoprotein cholesterol were found to be increased in DIO rats, but without any obvious changes in blood glucose or tumor necrosis factor-alpha levels.

CONCLUSION

11beta-HSD1 may promote preadipocyte differentiation, and may be involved in the development of obesity.

11beta-hydroxysteroid dehydrogenase type 1 mRNA is increased in both visceral and subcutaneous adipose tissue of obese patients

OBJECTIVE

Data from rodents provide evidence for a causal role of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) in the development of obesity and its complications. In humans, 11beta-HSD-1 is increased in subcutaneous adipose tissue (SAT) of obese patients, and higher adipose 11beta-HSD-1 was associated with features of the metabolic syndrome. To date, there is no evidence for an increased expression of 11beta-HSD-1 in human visceral adipose tissue (VAT), although VAT is the major predictor for insulin resistance and the metabolic syndrome.

RESEARCH METHODS AND PROCEDURES

11beta-HSD-1 and hexose-6-phosphate dehydrogenase (the enzyme responsible for the synthesis of nicotinamide adenine dinucleotide phosphate, the cofactor required for 11beta-HSD-1 oxoreductase activity) mRNA levels were measured using real-time quantitative reverse transcriptase-polymerase chain reaction in abdominal SAT and VAT biopsies obtained from 10 normal-weight and 12 obese women. Adiponectin mRNA was used as an internal control.

RESULTS

11beta-HSD-1 mRNA concentrations were significantly increased in both SAT and VAT of obese patients (720% and 450% of controls, respectively; p < 0.05) and correlated with hexose-6-phosphate dehydrogenase mRNA levels. The level of VAT 11beta-HSD-1 mRNA correlated with anthropometric parameters: BMI (r = 0.41, p = 0.05), waist circumference (r = 0.44, p = 0.04), abdominal sagittal diameter (r = 0.51, p = 0.02), and percentage fat (r = 0.51, p = 0.02).

DISCUSSION

Our results demonstrate for the first time that 11beta-HSD-1 mRNA expression is increased in VAT from obese patients. They strengthen the importance of 11beta-HSD-1 in human obesity and its associated complications and suggest the need of clinical studies with specific 11beta-HSD-1 inhibitors.

Obesity and the role of adipose tissue in inflammation and metabolism

Recent discoveries, notably of the hormones leptin and adiponectin, have revised the notion that adipocytes are simply a storage depot for body energy. Instead, adipocytes are also endocrine organs, with multiple metabolic roles in regulating whole-body physiology. Small adipocytes in lean individuals promote metabolic homeostasis; the enlarged adipocytes of obese individuals recruit macrophages and promote inflammation and the release of a range of factors that predispose toward insulin resistance. Exercise activates the AMP-activated protein kinase (AMPK) in muscle and other tissues, a pathway that increases fat oxidation and glucose transport. Importantly, the adipocyte hormones leptin and adiponectin also activate AMPK; remarkably, the same pathway is activated by certain antidiabetic agents such as thiazolidinediones. Increasingly, our understanding of the adipocyte as an endocrine organ is leading to new insights into obesity and health.

Cell-based assay for screening 11beta-hydroxysteroid dehydrogenase inhibitors using liquid chromatography/tandem mass spectrometry detection

Cortisol is an important glucocorticoid that regulates many physiological pathways by activating various intracellular receptors. The type 1 isozyme of 11beta-hydroxysteroid dehydrogenase (11beta-HSD1) functions in vivo predominantly as a reductase by converting cortisone into cortisol. A high-throughput liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed to screen for inhibitors of 11beta-HSD1 by monitoring cortisol and cortisone simultaneously. The injection cycle time can be as fast as 1 min/sample, making it amenable to the analysis of large numbers of the cell-assay samples in the screening of 11beta-HSD inhibitors. The reductase and dehydrogenase activities of 11beta-HSD1 are assessed separately.

A polygenic model of the metabolic syndrome with reduced circulating and intra-adipose glucocorticoid action

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.

Glucocorticoids act in the dorsal hindbrain to modulate baroreflex control of heart rate

Systemic corticosterone (Cort) modulates arterial baroreflex control of both heart rate and renal sympathetic nerve activity. Because baroreceptor afferents terminate in the dorsal hindbrain (DHB), an area with dense corticosteroid receptor expression, we tested the hypothesis that prolonged activation of DHB Cort receptors increases the midpoint and reduces the gain of arterial baroreflex control of heart rate in conscious rats. Small (3-4 mg) pellets of Cort (DHB Cort) or Silastic (DHB Sham) were placed on the surface of the DHB, or Cort was administered systemically by placing a Cort pellet on the surface of the dura (Dura Cort). Baroreflex control of heart rate was determined in conscious male Sprague Dawley rats on each of 4 days after initiation of treatment. Plots of arterial pressure vs. heart rate were analyzed using a four-parameter logistic function. After 3 days of treatment, the arterial pressure midpoint for baroreflex control of heart rate was increased in DHB Cort rats (123 +/- 2 mmHg) relative to both DHB Sham (108 +/- 3 mmHg) and Dura Cort rats (109 +/- 2 mmHg, P < 0.05). On day 4, baseline arterial pressure was greater in DHB Cort (112 +/- 2 mmHg) compared with DHB Sham (105 +/- 2 mmHg) and Dura Cort animals (106 +/- 2 mmHg, P < 0.05), and the arterial pressure midpoint was significantly greater than mean arterial pressure in the DHB Cort group only. Also on day 4, maximum baroreflex gain was reduced in DHB Cort (2.72 +/- 0.12 beats x min(-1) x mmHg(-1)) relative to DHB Sham and Dura Cort rats (3.51 +/- 0.28 and 3.37 +/- 0.27 beats x min(-1) x mmHg(-1), P < 0.05). We conclude that Cort acts in the DHB to increase the midpoint and reduce the gain of the heart rate baroreflex function.

Ontogeny and nutritional programming of adiposity in sheep: potential role of glucocorticoid action and uncoupling protein-2

Increased glucocorticoid action and adipose tissue inflammation contribute to excess adiposity. These adaptations may be enhanced in offspring exposed to nutrient restriction (NR) in utero, thereby increasing their susceptibility to later obesity. We therefore determined the developmental ontogeny of glucocorticoid receptor (GR), 11β-hydroxysteroid dehydrogenase (11βHSD) types 1 and 2, and uncoupling protein (UCP)-2 mRNA in perirenal adipose tissue between late gestation and 6 mo after birth in the sheep, as well as the effect of maternal NR targeted between early to mid (28–80 days, term ∼147 days)- or late (110–147 days) gestation. GR and 11βHSD1 mRNA increased with fat mass and were all maximal within the 6-mo observation period. 11βHSD2 mRNA abundance demonstrated a converse decline, whereas UCP2 peaked at 30 days. GR and 11βHSD1 mRNA abundance were strongly correlated with total and relative perirenal adipose tissue weight, and UCP2 was strongly correlated with GR and 11βHSD1 mRNA. Early- to midgestational NR increased GR, 11βHSD1, and UCP2 mRNA, but decreased 11βHSD2 mRNA abundance, an adaptation reversed with late-gestational NR. We conclude that the continual rise in glucocorticoid action and fat mass after birth may underlie the development of later obesity. The magnitude of this adaptation is partly dependent on maternal food intake through pregnancy.

The Metabolic Syndrome and Disturbances in Hormone Levels in Long-Term Survivors of Disseminated Testicular Cancer

Purpose

The metabolic syndrome may be an important risk factor for cardiovascular disease in long-term survivors of testicular cancer (TC). We investigated the associations between hormone levels and the metabolic syndrome in these men.

Patients and Methods

We included TC patients cured by orchidectomy and cisplatin-based chemotherapy, stage I TC patients after orchidectomy only, and healthy men of comparable age. Presence of the metabolic syndrome was determined using guidelines from the National Cholesterol Education Program Adult Treatment Panel III. Thyroid-stimulating hormone, follicle-stimulating hormone (FSH), inhibin B, luteinizing hormone (LH), total testosterone, sex-hormone–binding globulin, free testosterone, estradiol, dehydroepiandrosterone sulfate, and insulin-like growth factor 1 were determined in blood. Cortisol metabolite excretion was measured in urine.

Results

Eighty-six chemotherapy patients (median follow-up, 7 years) were compared with 44 stage I patients and 47 controls. LH and FSH were higher, and inhibin B and total and free testosterone were lower in chemotherapy patients than controls. Adrenal and thyroid hormone production were unaffected. Chemotherapy patients with the metabolic syndrome (n = 22; 26%) had a higher body mass index (BMI) pretreatment, a larger BMI increase during follow-up, lower total testosterone, and higher urinary cortisol metabolite excretion than those patients without the metabolic syndrome. BMI and insulin were associated with the metabolic syndrome, while total testosterone and urinary cortisol metabolite excretion were associated with BMI.

Conclusion

We found gonadal dysfunction, but normal adrenal and thyroid function. Through its association with BMI, testosterone may play a role in the development of the metabolic syndrome in long-term TC survivors.

The metabolic syndrome and cardiovascular risk in Cushing's syndrome

Cushing's syndrome (CS) is characterized by a series of systemic complications that increase cardiovascular risk and cause severe atherosclerotic damage that develops in parallel with an acquired metabolic syndrome. Short-term remission from hypercortisolism improves metabolic and vascular damages, but long-term remission from CS seems to be associated with similar or worse metabolic and vascular damage, probably because of persistent abdominal obesity or insulin resistance years after normalization of cortisol secretion. Study results suggest that an increased cardiovascular risk also may persist in patients who undergo treatment with exogenous glucocorticoids after therapy withdrawal. Considering the many patients subjected to corticosteroid treatment, this could be of great clinical relevance and should be investigated thoroughly.

11β-Hydroxysteroid Dehydrogenase Expression and Glucocorticoid Synthesis Are Directed by a Molecular Switch during Osteoblast Differentiation

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) plays an important role in the prereceptor regulation of corticosteroids by locally converting cortisone into active cortisol. To investigate the impact of this mechanism on osteoblast development, we have characterized 11β-HSD1 activity and regulation in a differentiating human osteoblast cell line (SV-HFO). Continuous treatment with the synthetic glucocorticoid dexamethasone induces differentiation of SV-HFO cells during 21 d of culture. Using this cell system, we showed an inverse relationship between 11β-HSD1 activity and osteoblast differentiation. 11β-HSD1 mRNA expression and activity were low and constant in differentiating osteoblasts. However, in the absence of differentiation (no dexamethasone), 11β-HSD1 mRNA and activity increased strongly from d 12 of culture onward, with a peak around d 19. Promoter reporter studies provided evidence that specific regions of the 11β-HSD1 gene are involved in this differentiation controlled regulation of the enzyme. Functional implication of these changes in 11β-HSD1 is shown by the induction of osteoblast differentiation in the presence of cortisone. The current study demonstrates the presence of an intrinsic differentiation-driven molecular switch that controls expression and activity of 11β-HSD1 and thereby cortisol production by human osteoblasts. This efficient mechanism by which osteoblasts generate cortisol in an autocrine fashion to ensure proper differentiation will help to understand the complex effects of cortisol on bone metabolism.

Conformational Flexibility in Crystal Structures of Human 11β-Hydroxysteroid Dehydrogenase Type I Provide Insights into Glucocorticoid Interconversion and Enzyme Regulation

Human 11beta-hydroxysteroid dehydrogenase type I (11beta-HSD1) is an ER-localized membrane protein that catalyzes the interconversion of cortisone and cortisol. In adipose tissue, excessive cortisol production through 11beta-HSD1 activity has been implicated in the pathogenesis of type II diabetes and obesity. We report here biophysical, kinetic, mutagenesis, and structural data on two ternary complexes of 11beta-HSD1. The combined results reveal flexible active site interactions relevant to glucocorticoid recognition and demonstrate how four 11beta-HSD1 C termini converge to form an as yet uncharacterized tetramerization motif. A C-terminal Pro-Cys motif is localized at the center of the tetramer and forms reversible enzyme disulfides that alter enzyme activity. Conformational flexibility at the tetramerization interface is coupled to structural changes at the enzyme active site suggesting how the central Pro-Cys motif may regulate enzyme activity. Together, the crystallographic and biophysical data provide a structural framework for understanding 11beta-HSD1 activities and will ultimately facilitate the development of specific inhibitors.

Use of 11alpha-deuterium labeled cortisol as a tracer for assessing reduced 11beta-HSD2 activity in vivo following glycyrrhetinic acid ingestion in a human subject

This study describes an oral administration of 5 mg of [1,2,4,19-13C4,11alpha-2H]cortisol (cortisol-13C4,2H1) to a human subject performed on two separate occasions, one with cortisol-13C4,2H1 alone and the other with cortisol-13C4,2H1 plus 130 mg per day of glycyrrhetinic acid for 6 days. The stable isotope methodology employed allowed for the evaluation of the individual in vivo activities of the two isozymes of 11beta-hydroxysteroid dehydrogenase (11beta-HSD), 11beta-HSD1 and 11beta-HSD2, and to demonstrate the sensitivity of changes in cortisol elimination half-life for detecting inhibition of 11beta-HSD2 activity induced with glycyrrhetinic acid. The kinetic analysis associated with the loss of 11alpha-2H during the conversion of cortisol-13C4,2H1 to cortisone-13C4 by 11beta-HSD2 clearly indicated reduced 11beta-HSD2 activity with glycyrrhetinic acid ingestion, as observed by an increase in the elimination half-life of cortisol-13C4,2H1. The elimination half-life of cortisol-13C4,2H1 provided sensitive in vivo measures of 11beta-HSD2 activity and was more sensitive for detecting changes in renal 11beta-HSD2 activity than the measurement of the urinary ratio of free cortisol and free cortisone (UFF/UFE). The 2H-labeling in the 11alpha-position of cortisol served as an appropriate tracer for assessing the reduced 11beta-HSD2 activity in vivo induced by glycyrrhetinic acid.

Postnatal diet-induced obesity in rats upregulates systemic and adipose tissue glucocorticoid metabolism during development and in adulthood: its relationship with the metabolic syndrome

In humans, a hyperactivity of glucocorticoid metabolism was postulated to be involved in the intrauterine programming of the metabolic syndrome in adulthood. We studied in rats the effects of overfeeding, obtained by reducing the size of the litter in the immediate postnatal period, a time crucial for neuroendocrine maturation such as late gestation in humans. Overfeeding induced early-onset obesity and accelerated the maturation of the hypothalamo-pituitary-adrenal (HPA) axis together with an upregulation of adipose tissue glucocorticoid receptor (GR) mRNA. In adulthood, neonatally overfed rats presented with moderate increases in basal and stress-induced corticosterone secretion and striking changes in visceral adipose tissue glucocorticoid signaling, that is, enhanced GR and 11beta-hydroxysteroid dehydrogenase type 1 mRNA levels. The above-mentioned alterations in the endocrine status of overfed rats were accompanied by a moderate overweight status and significant metabolic disturbances comparable to those described in the metabolic syndrome. Our data demonstrate for the first time that postnatal overfeeding accelerates the maturation of the HPA axis and leads to permanent upregulation of the HPA axis and increased adipose tissue glucocorticoid sensitivity. Thus, the experimental paradigm of postnatal overfeeding is a powerful tool to understand the pathophysiology of glucocorticoid-induced programming of metabolic axes.