Depot-specific messenger RNA expression of 11 beta-hydroxysteroid dehydrogenase type 1 and leptin in adipose tissue of children and adults

OBJECTIVE: To compare expression of messenger RNA (mRNA) coding for the cortisol regenerating enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), and the adipocytokines leptin and resistin in paired biopsies of subcutaneous adipose tissue (SC) and omental adipose tissue (OM) from children. DESIGN: Paired biopsies (SC and OM) were obtained from 54 children (age 0.17-16 years, body mass index (BMI) 12.5-28.3 kg/m(2), BMI standard deviation score (SDS) -2.5-4.5) and 16 adults (age 27-79 years, BMI 19-46 kg/m(2)) undergoing open abdominal surgery. mRNA levels of 11beta-HSD1, leptin and resistin were measured using quantitative real-time polymerase chain reaction (PCR). RESULTS: 11beta-HSD1 mRNA level was higher in OM than in SC (P<0.05), whereas leptin mRNA was higher in SC than in OM (P<0.001). There was no difference in the resistin mRNA level between SC and OM. These results were consistent in children and adults. In children, 11beta-HSD1 mRNA in SC was positively associated with BMI SDS (P<0.05), whereas in OM it was positively associated with age (P<0.05). The association between 11beta-HSD1 expression and age remained significant after adjustment for BMI SDS and gender. Leptin mRNA was positively associated with BMI SDS (SC: P<0.001, OM: P<0.001) but not with age in children. In multiple regression analyses, including anthropometric variables and age, BMI SDS was independently associated with mRNA levels of 11beta-HSD1 (P<0.05) and leptin (P<0.001) in SC. When normal weight and overweight children were analyzed separately, 11beta-HSD1 mRNA levels were positively associated with leptin in OM in the overweight group (P<0.05). CONCLUSION: There are depot-specific differences in mRNA levels of 11beta-HSD1 and leptin in children and adults. The positive association of 11beta-HSD1 mRNA in OM with age may reflect a causal role in visceral fat accumulation during growth. Increasing 11beta-HSD1 and leptin mRNA in SC with increasing BMI SDS could suggest that the risk of metabolic consequences of obesity may be established early in life.     

Weight loss increases 11beta-hydroxysteroid dehydrogenase type 1 expression in human adipose tissue

The global epidemic of obesity has heightened the need to understand the mechanisms that underpin its pathogenesis. Clinical observations in patients with Cushing's syndrome have highlighted the link between cortisol and central obesity. However, although circulating cortisol levels are normal or reduced in obesity, local regeneration of cortisol, from inactive cortisone, by 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) has been postulated as a pathogenic mechanism. Although levels of expression of 11betaHSD1 in adipose tissue in human obesity are debated in the literature, global inhibition of 11betaHSD1 improves insulin sensitivity. We have determined the effects of significant weight loss on cortisol metabolism and adipose tissue 11betaHSD1 expression after 10-wk ingestion of a very low calorie diet in 12 obese patients (six men and six women; body mass index, 35.9 +/- 0.9 kg/m2; mean +/- SE). All patients achieved significant weight loss (14.1 +/- 1.3% of initial body weight). Total fat mass fell from 41.8 +/- 1.9 to 32.0 +/- 1.7 kg (P < 0.0001). In addition, fat-free mass decreased (64.4 +/- 3.4 to 58.9 +/- 2.9 kg; P < 0.0001) and systolic blood pressure and total cholesterol also fell [systolic blood pressure, 135 +/- 5 to 121 +/- 5 mm Hg (P < 0.01); total cholesterol, 5.4 +/- 0.2 to 4.8 +/- 0.2 mmol/liter (P < 0.05)]. The serum cortisol/cortisone ratio increased after weight loss (P < 0.01). 11betaHSD1 mRNA expression in isolated adipocytes increased 3.4-fold (P < 0.05). Decreased 11betaHSD1 activity and expression in obesity may act as a compensatory mechanism to enhance insulin sensitivity through a reduction in tissue-specific cortisol concentrations. Inhibition of 11betaHSD1 may therefore be a novel, therapeutic strategy for insulin sensitization.     

Regulation of expression of 11beta-hydroxysteroid dehydrogenase type 1 in adipose tissue: tissue-specific induction by cytokines

Patients with glucocorticoid excess develop central obesity, yet in simple obesity, circulating glucocorticoid levels are normal. We have suggested that the increased activity and expression of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) generating active cortisol from cortisone within adipose tissue may be crucial in the pathogenesis of obesity. In this study primary cultures of human hepatocytes and adipose stromal cells (ASC) were used as in vitro models to investigate the tissue-specific regulation of 11betaHSD1 expression and activity. Treatment with tumor necrosis factor-alpha (TNFalpha) caused a dose-dependent increase in 11betaHSD1 activity in primary cultures of both sc [1743.1 +/- 1015.4% (TNFalpha, 10 ng/ml); P < 0.05 vs. control (100%)] and omental [375.8 +/- 57.0% (TNFalpha, 10 ng/ml); P < 0.01 vs. control (100%)] ASC, but had no effect on activity in human hepatocytes [90.2 +/- 2.8% (TNFalpha, 10 ng/ml); P = NS vs. control (100%)]. Insulin-like growth factor I (IGF-I) caused a dose-dependent inhibition of 11betaHSD1 activity in sc [49.7 +/- 15.0% (IGF-I, 100 ng/ml]; P < 0.05 vs. control (100%)] and omental [71.6 +/- 7.5 (IGF-I, 100 ng/ml); P < 0.01 vs. control (100%)] stromal cells, but not in human hepatocytes [101.8 +/- 15.7% (IGF-I, 100 ng/ml); P = NS vs. control (100%)]. Leptin treatment did not alter 11betaHSD1 activity in human hepatocytes, but increased activity in omental ASC [135.8 +/- 14.1% (leptin, 100 ng/ml); P = 0.08 vs. control (100%)]. Treatment with interleukin-1beta induced 11betaHSD1 activity and expression in sc and omental ASC in a time- and dose-dependent manner. 15-Deoxy-12,14-PGJ2, the putative endogenous ligand of the orphan nuclear receptor peroxisome proliferator-gamma, significantly increased 11betaHSD1 activity in omental cells [179.7 +/- 29.6% (1 microM); P < 0.05 vs. control (100%)] and sc [185.3 +/- 12.6% (1 microM); P < 0.01 vs. control (100%)] ASC, and it is possible that expression of this ligand may ensure continued cortisol generation to permit adipocyte differentiation. Protease inhibitors used in the treatment of human immunodeficiency virus infection are known to cause a lipodystrophic syndrome and central obesity, but saquinavir, indinavir, and neflinavir caused a dose-dependent inhibition of 11betaHSD1 activity in primary cultures of human omental ASC. 11betaHSD1 expression is increased in human adipose tissue by TNFalpha, interleukin-1beta, leptin, and orphan nuclear receptor peroxisome proliferator-gamma agonists, but is inhibited by IGF-I. This autocrine and/or paracrine regulation is tissue specific and explains recent clinical data and animal studies evaluating cortisol metabolism in obesity. Tissue-specific 11betaHSD1 regulation offers the potential for selective enzyme inhibition within adipose tissue as a novel therapy for visceral obesity.     

Expression of 11beta-hydroxysteroid dehydrogenase type 1 in adipose tissue is not increased in human obesity

Central obesity is associated with increased morbidity and mortality. Preadipocyte proliferation and differentiation contribute to increases in adipose tissue mass, yet the mechanisms that underlie these processes remain unclear. Patients with glucocorticoid excess develop a reversible form of central obesity, but circulating cortisol levels in idiopathic obesity are invariably normal. We have hypothesized that the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), by converting inactive cortisone to active cortisol in adipose tissue, might be an important autocrine regulator of fat mass. Paired omental and sc fat biopsies were obtained from 32 women (median age, 43 yr; range, 28-65; median body mass index, 27.5 kg/m(2); range, 19.7-39.2) undergoing elective abdominal surgery. 11beta-HSD1 activity and mRNA levels were assessed in whole tissue and in isolated preadipocytes and adipocytes using specific enzyme assays and real-time PCR. Preadipocyte proliferation was measured using tritiated thymidine incorporation. Whole adipose tissue 11beta-HSD1 mRNA levels did not differ between omental and sc samples (P = 0.73). In addition, mRNA levels did not correlate with body mass index (omental: r = 0.1; P = 0.6; sc: r = 0.15; P = 0.4). In keeping with earlier studies, 11beta-HSD1 mRNA levels were higher in omental compared with sc preadipocytes. However, in cultured omental preadipocytes, 11beta-HSD1 activity inversely correlated with body mass index (r = -0.47; P = 0.03). In omental preadipocytes, both cortisol and cortisone decreased proliferation (P < 0.05). Inhibition of 11beta-HSD1 with glycyrrhetinic acid partially reversed the cortisone-induced decrease in preadipocyte proliferation (P < 0.05). Enhanced preadipocyte proliferation within omental adipose tissue as a consequence of decreased 11beta-HSD1 mRNA levels and activity may contribute to increases in visceral adipose tissue mass in obese patients.     

The glucose-6-phosphate transporter-hexose-6-phosphate dehydrogenase-11beta-hydroxysteroid dehydrogenase type 1 system of the adipose tissue

11beta-hydroxysteroid dehydrogenase type 1, expressed mainly in the endoplasmic reticulum of adipocytes and hepatocytes, plays an important role in the prereceptorial activation of glucocorticoids. In liver endoplasmic reticulum-derived microsomal vesicles, nicotinamide adenine dinucleotide phosphate reduced supply to the enzyme is guaranteed by a tight functional connection with hexose-6-phosphate dehydrogenase and the glucose-6-phosphate transporter (G6PT). In adipose tissue, the proteins and their activities supporting the action of 11beta-hydroxysteroid dehydrogenase type 1 have not been explored yet. Here we report the occurrence of the hexose-6-phosphate dehydrogenase in rat epididymal fat, as detected at the level of mRNA, protein, and activity. In the isolated microsomes, the activity was evident only on the permeabilization of the membrane because of the poor permeability to the cofactor nicotinamide adenine dineucleotide phosphate (NADP(+)), which is consistent with the intralumenal compartmentation of both the enzyme and a pool of pyridine nucleotides. In fat cells, the access of the substrate, glucose-6-phosphate to the intralumenal hexose-6-phosphate dehydrogenase appeared to be mediated by the liver-type G6PT. In fact, the G6PT expression was revealed at the level of mRNA and protein. Accordingly, the transport of glucose-6-phosphate was demonstrated in microsomal vesicles, and it was inhibited by S3483, a prototypic inhibitor of G6PT. Furthermore, isolated adipocytes produced cortisol on addition of cortisone, and the production was markedly inhibited by S3483. The results show that adipocytes are equipped with a functional G6PT-hexose-6-phosphate dehydrogenase-11beta-hydroxysteroid dehydrogenase type 1 system and indicate that all three components are potential pharmacological targets for modulating local glucocorticoid activation.     

Tissue-specific changes in peripheral cortisol metabolism in obese women: increased adipose 11beta-hydroxysteroid dehydrogenase type 1 activity

Cushing's syndrome and the metabolic syndrome share clinical similarities. Reports of alterations in the hypothalamic-pituitary-adrenal (HPA) axis are inconsistent, however, in the metabolic syndrome. Recent data highlight the importance of adipose 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), which regenerates cortisol from cortisone and, when overexpressed in fat, produces central obesity and glucose intolerance. Here we assessed the HPA axis and 11beta-HSD1 activity in women with moderate obesity and insulin resistance. Forty women were divided into tertiles according to body mass index (BMI; median, 22.0, 27.5, and 31.4, respectively). Serum cortisol levels were measured after iv CRH, low dose dexamethasone suppression, and oral cortisone administration. Urinary cortisol metabolites were measured in a 24-h sample. A sc abdominal fat biopsy was obtained in 14 participants for determination of 11beta-HSD type 1 activity in vitro. Higher BMI was associated with higher total cortisol metabolite excretion (r = 0.49; P < 0.01), mainly due to increased 5alpha- and, to a lesser extent, 5beta-tetrahydrocortisol excretion, but no difference in plasma cortisol basally, after dexamethasone, or after CRH, and only a small increase in the ACTH response to CRH. Hepatic 11beta-HSD1 conversion of oral cortisone to cortisol was impaired in obese women (area under the curve, 147,736 +/- 28,528, 115,903 +/- 26,032, and 90,460 +/- 18,590 nmol/liter.min; P < 0.001). However, 11beta-HSD activity in adipose tissue was positively correlated with BMI (r = 0.55; P < 0.05). In obese females increased reactivation of glucocorticoids in fat may contribute to the characteristics of the metabolic syndrome. Increased inactivation of cortisol in liver may be responsible for compensatory activation of the HPA axis. These alterations in cortisol metabolism may be a basis for novel therapeutic strategies to reduce obesity-related complications.     

Inhibition of 11beta-hydroxysteroid dehydrogenase type 1 activity in vivo limits glucocorticoid exposure to human adipose tissue and decreases lipolysis

CONTEXT: The pathophysiological importance of glucocorticoids (GCs) is exemplified by patients with Cushing's syndrome who develop hypertension, obesity, and insulin resistance. At a cellular level, availability of GCs to the glucocorticoid and mineralocorticoid receptors is controlled by the isoforms of 11beta-hydroxysteroid dehydrogenase (11beta-HSD). In liver and adipose tissue, 11beta-HSD1 converts endogenous, inactive cortisone to active cortisol but also catalyzes the bioactivation of the synthetic prednisone to prednisolone. OBJECTIVE: The objective of the study was to compare markers of 11beta-HSD1 activity and demonstrate that inhibition of 11beta-HSD1 activity limits glucocorticoid availability to adipose tissue. DESIGN AND SETTING: This was a clinical study. PATIENTS: Seven healthy male volunteers participated in the study. INTERVENTION: Intervention included carbenoxolone (CBX) single dose (100 mg) and 72 hr of continuous treatment (300 mg/d). MAIN OUTCOME MEASURES: Inhibition of 11beta-HSD1 was monitored using five different mechanistic biomarkers (serum cortisol and prednisolone generation, urinary corticosteroid metabolite analysis by gas chromatography/mass spectrometry, and adipose tissue microdialysis examining cortisol generation and glucocorticoid-mediated glycerol release). RESULTS: Each biomarker demonstrated reduced 11beta-HSD1 activity after CBX administration. After both a single dose and 72 hr of treatment with CBX, cortisol and prednisolone generation decreased as did the urinary tetrahydrocortisol+5alpha-tetrahydrocortisol to tetrahydrocortisone ratio. Using adipose tissue microdialysis, we observed decreased interstitial fluid cortisol availability with CBX treatment. Furthermore, a functional consequence of 11beta-HSD1 inhibition was observed, namely decreased prednisone-induced glycerol release into adipose tissue interstitial fluid indicative of inhibition of GC-mediated lipolysis. CONCLUSION: CBX is able to inhibit rapidly the generation of active GC in human adipose tissue. Importantly, limiting GC availability in vivo has functional consequences including decreased glycerol release.     

Inhibition of 11beta-hydroxysteroid dehydrogenase type 1 in obesity

Excessive glucocorticoid exposure (Cushing's syndrome) results in increased adiposity associated with dysmetabolic features (including insulin resistance, hyperlipidaemia, and hypertension). Circulating cortisol levels are not elevated in idiopathic obesity, although cortisol production and clearance are increased. However, tissue glucocorticoid exposure may be altered independently of circulating levels by 11β-hydroxysteroid dehydrogenase type 1 (11HSD1), an enzyme which generates active glucocorticoid within tissues, including in adipose tissue. Transgenic overexpression of 11HSD1 in mice causes obesity. In human obesity, 11HSD1 is altered in a tissue-specific manner with reduced levels in liver but elevated levels in adipose, which may lead to glucocorticoid receptor activation and contribute to the metabolic phenotype. The reasons for altered 11HSD1 in obesity are not fully understood. Although some polymorphisms have been demonstrated in intronic and upstream regions of the HSD11B1 gene, the functional significance of these is not clear. In addition, there is mounting evidence that 11HSD1 may be dysregulated secondarily to factors that are altered in obesity, including substrates for metabolism, hormones, and inflammatory mediators. 11HSD1 is a potential therapeutic target for the treatment of the metabolic syndrome. 11HSD1 knockout mice are protected from diet-induced obesity and associated metabolic dysfunction. Although many specific inhibitors of 11HSD1 have now been developed, and published data support their efficacy in the liver to reduce glucose production, their efficacy in enhancing insulin sensitivity in adipose tissue remains uncertain. The therapeutic potential of 11HSD1 in human obesity therefore remains highly promising but as yet unproven.     

Adipose tissue 11beta-hydroxysteroid dehydrogenase type 1 expression in obesity and Cushing's syndrome

OBJECTIVE: To evaluate the expression of 11beta-hydrxysteroid dehydrogenase type 1 (11beta-HSD1) in omental adipose tissue of patients with Cushing's syndrome and simple obesity, compared with normal weight controls. DESIGN AND METHODS: We have performed a case-control study and studied omental adipose tissue from a total of 24 subjects (eight obese subjects, ten patients with Cushing's syndrome due to adrenal adenoma, and six normal weight controls). Body mass index, blood pressure, plasma glucose, plasma insulin, plasma cortisol, urinary free cortisol and post dexamethasone plasma cortisol were measured with standard methods. 11beta-HSD1 mRNA and protein expression were evaluated in real-time PCR and western blot analysis respectively. RESULTS: 11beta-HSD1 mRNA was 13-fold higher in obese subjects compared with controls (P=0.001). No differences were found between Cushing's patients and controls. Western blot analysis supported the mRNA expression results. CONCLUSIONS: Our data show the involvement of 11beta-HSD1 enzyme invisceral obesity, which is more evident in severely obese patients than in Cushing's syndrome patients. The lack of increase of 11beta-HSD1 expression in Cushing's syndrome could suggest downregulation of the enzyme as a result of long-term overstimulation.     

Effects of peroxisome proliferator-activated receptor-alpha and -gamma agonists on 11beta-hydroxysteroid dehydrogenase type 1 in subcutaneous adipose tissue in men

CONTEXT: In animals, peroxisome proliferator-activated receptor-alpha (PPARalpha) and PPARgamma agonists down-regulate 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) mRNA and activity in liver and adipose tissue, respectively, and PPARgamma agonists reduce ACTH secretion from corticotrope cells. OBJECTIVE: Our objective was to test whether PPAR agonists alter cortisol secretion and peripheral regeneration by 11beta-HSD1 in humans and whether reduced cortisol action contributes to metabolic effects of PPARgamma agonists. DESIGN AND SETTING: Three randomized placebo-controlled crossover studies were conducted at a clinical research facility. PATIENTS AND PARTICIPANTS: Healthy men and patients with type 2 diabetes participated. INTERVENTIONS, OUTCOME MEASURES, AND RESULTS: In nine healthy men, 7 d of PPARalpha agonist (fenofibrate) or PPARgamma agonist (rosiglitazone) had no effect on cortisol secretion, hepatic cortisol generation after oral cortisone administration, or tracer kinetics during 9,11,12,12-[(2)H](4)-cortisol infusion, although rosiglitazone marginally reduced cortisol generation in sc adipose tissue measured by in vivo microdialysis. In 12 healthy men, 4-5 wk of rosiglitazone increased insulin sensitivity during insulin infusion but did not change 11beta-HSD1 mRNA or activity in sc adipose tissue, and insulin sensitization was unaffected by glucocorticoid blockade with a combination of metyrapone and RU38486. In 12 men with type 2 diabetes 12 wk of rosiglitazone reduced arteriovenous cortisone extraction across abdominal sc adipose tissue and reduced 11beta-HSD1 mRNA in sc adipose tissue but increased plasma cortisol concentrations. CONCLUSIONS: Neither PPARalpha nor PPARgamma agonists down-regulate 11beta-HSD1 or cortisol secretion acutely in humans. The early insulin-sensitizing effect of rosiglitazone is not dependent on reducing intracellular glucocorticoid concentrations. Reduced adipose 11beta-HSD1 expression and increased plasma cortisol during longer therapy with rosiglitazone probably reflect indirect effects, e.g. mediated by changes in body fat.     

Progesterone metabolism in the human kidney and inhibition of 11beta-hydroxysteroid dehydrogenase type 2 by progesterone and its metabolites

Progesterone binds with high affinity to the mineralocorticoid (MC) receptor, but confers only very low agonistic MC activity. Therefore, progesterone is a potent MC antagonist in vitro. Although progesterone reaches up to 100 times higher plasma levels in late pregnancy than aldosterone, the in vivo MC antagonistic effect of progesterone seems to be relatively weak. One explanation for this phenomenon could be local metabolism of progesterone in the human kidney, similar to the inactivation of cortisol to cortisone by the 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 2. We studied the metabolism of progesterone in the human kidney in vitro and found reduction to 20alpha-dihydro (DH)-progesterone as the main metabolite. Ring-A reduction to 5alpha-DH-progesterone, 20alpha-DH-5alpha-DH-progesterone, and 3beta,5alpha-tetrahydro (TH)-progesterone was also documented. We further showed for the first time that 17-hydroxylation of progesterone (17alpha-OH-progesterone, 17alpha-OH, 20alpha-DH-progesterone), normally localized in the adrenals and the gonads, occurs in the human adult kidney. We found no formation of deoxycorticosterone from progesterone in the human adult kidney. Using human kidney cortex microsomes, we tested the inhibitory potency of progesterone and its metabolites on the 11beta-HSD type 2. The most potent inhibitor was progesterone itself (IC50 = 4.8 x 10(-8) mol/L), followed by 5alpha-DH-progesterone (IC50 = 2.4 x 10(-7) mol/L), 20alpha-DH-progesterone, 3beta,5alpha-TH-progesterone, 17alpha-OH-progesterone, and 20alpha-DH-5alpha-DH-progesterone (IC50 between 7.7 x 10(-7) mol/L and 1.3 x 10(-6) mol/L). The least potent inhibitor was 17alpha-OH,20alpha-DH-progesterone. In addition to progesterone metabolism by the kidney, the inhibition of 11beta-HSD type 2 by progesterone and its metabolites could be a second explanation for the weak MC-antagonist activity of progesterone in vivo. Inhibition of 11beta-HSD type 2 leads to an increase of intracellular cortisol in a way that the local equilibrium between the MC agonist cortisol and the antagonist progesterone is shifted to the agonist side.     

Selective inhibition of 11beta-hydroxysteroid dehydrogenase type 1 decreases blood glucose concentrations in hyperglycaemic mice

AIMS/HYPOTHESIS: Current pharmacological treatments for Type II (non-insulin-dependent) diabetes mellitus have various limitations. New treatments are needed to reduce long-term risks for diabetic complications and mortality. We tested a new principle for lowering blood glucose. It is well known that glucocorticoids in excess cause glucose intolerance and insulin resistance. The enzymes 11beta-hydroxysteroid dehydrogenase type 1 and type 2 inter-convert inactive and active glucocorticoids, thereby playing a major role in local modulation of agonist concentration and activation of corticosteroid receptors in target tissues. It has been hypothesized that selective inhibition of 11beta-hydroxysteroid dehydrogenase type 1 decreases excessive hepatic glucose production in hyperglycemia and diabetes. BVT.2733 is a new, small molecule, non-steroidal, isoform-selective inhibitor of mouse 11beta-hydroxysteroid dehydrogenase type 1. The aim of the present study is to test if selective inhibition of 11beta-hydroxysteroid dehydrogenase type 1 lowers blood glucose concentrations in a hyperglycaemic and hyperinsulinaemic mouse model. METHODS: BVT.2733 was given to spontaneously hyperglycaemic KKA(y) mice for 7 days using subcutaneous osmotic mini-pumps. RESULTS: BVT.2733 lowered hepatic PEPCK and glucose-6-phosphatase mRNA, blood glucose and serum insulin concentrations compared with vehicle treated mice. In contrast, hepatic 11beta-hydroxysteroid dehydrogenase type 1 mRNA, liver function marker enzyme expression (aspartate aminotransferase, alanine aminotransferase and alkaline phosphatases), daily food intake and body weight were not altered by the treatment. CONCLUSION/INTERPRETATION: These results suggest that a selective inhibitor of human 11beta-hydroxysteroid dehydrogenase type 1 can become a new approach for lowering blood glucose concentrations in Type II diabetes.     

Hexose-6-phosphate dehydrogenase and 11beta-hydroxysteroid dehydrogenase-1 tissue distribution in the rat

Intracellular concentrations of the glucocorticoids cortisol and corticosterone are modulated by the enzymes 11beta-hydroxysteroid dehydrogenase (11beta-HSD) 1 and 2. 11beta-HSD1 is a reduced nicotinamide adenine dinucleotide phosphate (NADPH)-dependent microsomal reductase that converts the inactive glucocorticoids cortisone and 11-dehydrocorticosterone to their active forms, cortisol and corticosterone. Hexose-6-phosphate dehydrogenase (H6PDH) is an enzyme that generates NADPH from oxidized NADP (NADP(+)) within the endoplasmic reticulum. In the absence of NADPH or H6PDH to regenerate NADPH, 11beta-HSD1 acts as a dehydrogenase and inactivates glucocorticoids, as does 11beta-HSD2. A monoclonal antibody against H6PDH was produced to study the possibility that 11beta-HSD1 in the absence of H6PDH may be responsible for hydroxysteroid dehydrogenase activity in tissues that do not express significant amounts of 11beta-HSD2. H6PDH and 11beta-HSD1 expression was surveyed in a variety of rat tissues by real-time RT-PCR, Western blot analysis, and immunohistochemistry. H6PDH was found in a wide variety of tissues, with the greatest concentrations in the liver, kidney, and Leydig cells. Although the brain as a whole did not express significant amounts of H6PDH, some neurons were clearly immunoreactive by immunohistochemistry. H6PDH was amply expressed in most tissues examined in which 11beta-HSD1 was also expressed, with the notable exception of the renal interstitial cells, in which dehydrogenase activity by 11beta-HSD1 probably moderates activation of the glucocorticoid receptor because rat renal interstitial cells do not have significant amounts of mineralocorticoid receptors. This antibody against the H6PDH should prove useful for further studies of enzyme activity requiring NADPH generation within the endoplasmic reticulum.     

Adipose tissue expression of 11beta-hydroxysteroid dehydrogenase type 1 in Cushing's syndrome and in obesity

Glucocorticoids have a major role in determining adipose tissue metabolism and distribution. 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) is a NADPH-dependent enzyme highly expressed in the liver and adipose tissue. In most intact cells and tissues it functions as a reductase (to convert inactive cortisone to active cortisol). It has been hypothesized that tissue-specific deregulation of cortisol metabolism may be involved in the complex pathophysiology of the metabolic syndrome (MS) and obesity. Transgenic mice overexpressing 11betaHSD1 in adipose tissue develop obesity with all features of the MS, whereas 11betaHSD1-knockout mice are protected from both. The bulk of evidences points to an overexpression and increased activity of 11betaHSD1 also in human adipose tissue. However, 11betaHSD1 seems to adjust local cortisol concentrations independently of its plasma levels. In Cushing's syndrome, 11betaHSD1 is downregulated and may not be responsible for the abdominal fat depots; it also undergoes downregulation in response to weight loss in human obesity. The nonselective 11betaHSD1 inhibitor carbenoxolone improves insulin sensitivity in humans, and selective inhibitors enhance insulin action in diabetic mice liver, thereby lowering blood glucose. Thus, 11betaHSD1 is now emerging as a modulator of energy partitioning and a promising pharmacological target to treat the MS and diabetes.     

11 beta-hydroxysteroid dehydrogenase type 1 is a predominant 11 beta-reductase in the intact perfused rat liver

11 beta-Hydroxysteroid dehydrogenase type 1 (11 beta-HSD-1), a regulator of intrahepatocellular glucocorticoid activity, is bidirectional in homogenates but catalyses 11 beta-reduction (regenerating glucocorticoid) in intact primary hepatocytes in culture. To examine this discrepancy at the whole-organ level, we examined 11 beta-HSD-1 activity in the intact bivascularly perfused rat liver. On a single pass through male rat liver, 44+/-5% of 11-dehydrocorticosterone (11-DHC) recovered was 11 beta-reduced to corticosterone, whereas 10+/-1% of corticosterone was 11 beta-dehydrogenated to 11-DHC. 11 beta-Reduction was less in female liver (21+/-2%, P<0.01) and was significantly greater with perfusion of all substrate via the portal vein (50+/-3%) than via the hepatic artery (30+/-2%, P<0.05). 11 beta-Reductase activity was not saturated by 11-DHC (10(-)(9)-10(-)(6) M). Perfusion with carbenoxolone (CBX, 10(-)(6)-10(-)(3 )M) did not alter 11 beta-reduction of 11-DHC. In contrast, pretreatment with CBX in vivo (10 mg/day) for 7 days inhibited 11 beta-reductase (19+/-4% conversion, P<0.01). Concentrations of 11-DHC in male rat plasma were 44+/-6 nM. Thus 11 beta-HSD-1 is predominantly an 11 beta-reductase in the intact rat liver and is only inhibited by chronic administration of CBX. The substantial concentrations of plasma 11-DHC as substrate suggest that 11 beta-HSD-1 activity and its potential selective inhibition could modify glucocorticoid action in vivo.     

Reduced 11beta-hydroxysteroid dehydrogenase type 1 activity in obese boys

OBJECTIVE: The incidence of childhood obesity and type 2 diabetes has reached epidemic proportions. Glucocorticoid excess causes central obesity and diabetes mellitus as seen in Cushing's syndrome. The 11beta-hydroxysteroid dehydrogenase type 1 enzyme (11beta-HSD1) regenerates active cortisol from inactive cortisone. Altered 11beta-HSD1 may cause tissue-specific Cushing's syndrome with central obesity and impaired glucose homeostasis. DESIGN, PATIENTS, AND METHODS: Clinical and laboratory characteristics, and anthropometric measurements were determined in 15 male and 6 female obese pubertal children (aged 12-18 years, Tanner stages 2-5). In addition, analyses of 24-h excretion rates of glucocorticoids were also performed in 21 age-, sex-, and pubertal stage-matched non-obese children using gas chromatographic-mass spectrometric (GC-MS) analysis. RESULTS: 11beta-HSD1 activity (urinary tetrahydrocortisol (THF) + 5alpha-THF/tetrahydrocortisone (THE) ratio) was lower in obese when compared with non-obese boys. In addition, obese children had a higher total cortisol metabolite excretion than non-obese children. 11beta-HSD1 activity was significantly related to age in lean and obese children. Standard deviation score (SDS)-body mass index did not correlate with 11beta-HSD1 activity, or with total cortisol metabolite excretion within each group. In obese children, 11beta-HSD1 activity and total cortisol metabolite excretion showed no correlation to waist-to-hip ratio, fat mass (percentage of body mass), or the homeostasis model assessment of insulin resistance index. CONCLUSIONS: In conclusion, our findings strongly suggest that 11beta-HSD1 activity increases with age, and is reduced in obese boys. In addition, obese children have a higher total cortisol metabolites excretion suggesting a stimulated hypothalamus-pituitary-adrenal axis.     

Growth hormone (GH) substitution in GH-deficient patients inhibits 11beta-hydroxysteroid dehydrogenase type 1 messenger ribonucleic acid expression in adipose tissue

CONTEXT: Local tissue activity of glucocorticoids is in part determined by the isoenzymes 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD1) and 11beta-HSD2, interconverting inert cortisone and active cortisol. Increased tissue activity of cortisol may play a central role in the features of GH deficiency and the metabolic syndrome. OBJECTIVE: We investigated the effects of GH treatment on adipose tissue 11beta-HSD mRNA. SUBJECTS AND METHODS: A randomized placebo-controlled double-blind study design was used. Twenty-three GH-deficient patients (16 males and seven females) were randomized to 4 months of GH treatment (2 IU/m2) (n = 11) or placebo treatment (n = 12). Adipose tissue biopsies and blood samples were obtained before and after treatment. Biopsies were obtained from the abdominal sc depot at the level of the umbilicus and do not necessarily reflect the metabolically more important visceral adipose tissue. Gene expressions were determined by real-time RT-PCR. RESULTS: GH treatment decreased 11beta-HSD1 mRNA 66% [95% confidence interval (CI), 23-107%; P < 0.01] and increased 11beta-HSD2 mRNA 167% (95% CI, 33-297%; P < 0.05) in adipose tissue. Serum IGF-I and IGF-I mRNA increased in the GH-treated group by 187% (95% CI, 122-250%; P < 0.001) and 470% (95% CI, 88-846%; P < 0.01). The change in 11beta-HSD1 mRNA expression was negatively correlated with the change in serum IGF-I (R = -0.434; P < 0.05). In contrast, the change in 11beta-HSD2 mRNA expression was positively correlated with the change in serum IGF-I (R = 0.487; P < 0.05), and even stronger with the change in IGF-I mRNA expression (R = 0.798; P < 0.0001). CONCLUSION: GH treatment is able to decrease 11beta-HSD1 mRNA and increase 11beta-HSD2 and accordingly may be able to reduce the amount of locally produced cortisol in adipose tissue.