Effect of a peroxisome proliferator on 3 beta-hydroxysteroid dehydrogenase

To better understand the changes that occur following exposure to peroxisome proliferators, we utilized mRNA differential display and microarray to screen for peroxisome proliferator target genes apart from those involved in lipid metabolism in male C57B6 mice by using the ubiquitous plasticizer, di(2-ethylhexyl)phthalate (DEHP). One noted change was the dose-dependent suppression of the mouse hormone metabolizing 3 beta-hydroxysteroid dehydrogenase V (HSD3b5), which is specifically expressed in the male mouse liver. Northern analysis showed that HSD3b5 mRNA levels decreased dramatically upon one-day exposure to 2.0% dietary DEHP, and were nearly undetectable by one week of treatment. Food restriction also significantly suppressed HSD3b5 expression; however, in this case the suppression was delayed and to a lesser extent. Another mouse 3 beta-hydroxysteroid dehydrogenase, HSD3b4, predominantly expressed in kidneys, was also regulated by DEHP and food restriction. The sex-specific gene, HSD3b5, was affected more by DEHP and food restriction than the tissue-specific gene, HSD3b4.     

Analysis and characteristics of multiple types of human 17beta-hydroxysteroid dehydrogenase

Androgens and estrogens are not only synthesized in the gonads but also in peripheral target tissues. Accordingly, recent molecular cloning has allowed us to identify multiple types of 17β-hydroxysteroid dehydrogenases (17β-HSD), the key and exclusive enzymes involved in the formation and inactivation of sex steroids. However, only one form, namely, type 3 17β-HSD, is responsible for pseudohermaphroditism in deficient boys. To date, seven human 17β-HSDs have been isolated and characterized. Although they catalyze substrates having a similar structure, 17β-HSDs have very low homology. In intact cells in culture, these enzymes catalyze the reaction in a unidirectional way — types 1, 3, 5 and 7 catalyze the reductive reaction, while types 2, 4 and 8 catalyze the oxidative reaction. It is noteworthy that rat type 6 17β-HSD also catalyzes the reaction in the oxidative direction. In this report, we analyze the different characteristics of the multiple types of human 17β-HSD.     

Bis-aryl triazoles as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1

3-Aryl-5-phenyl-(1,2,4)-triazoles were identified as selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). They are active in both in vitro and an in vivo mouse pharmacodynamic (PD) model. The synthesis and structure activity relationships are presented.     

Glycyrrhizic acid suppresses type 2 11 beta-hydroxysteroid dehydrogenase expression in vivo

Licorice-derivatives such as glycyrrhizic acid (GA) competitively inhibit 11β-hydroxysteroid dehydrogenase(11β-HSD) type 2 (11-HSD2) enzymatic activity, and chronic clinical use often results in pseudoaldosteronism. Since the effect of GA on 11-HSD2 expression remains unknown, we undertook in vivo and in vitro studies. Male Wistar rats were given 30, 60 or 120 mg/kg of GA twice a day for 2 weeks. Plasma corticosterone was decreased in those given the 120 mg dose, while urinary corticosterone excretion was increased in those given the 30 and 60 mg doses but decreased in those given 120 mg GA. NAD⁺-dependent dehydrogenase activity in kidney microsomal fraction was decreased in animals receiving doses of 60 and 120 mg GA. The 11-HSD2 protein and mRNA levels were decreased in those given 120 mg GA. In contrast, in vitro studies using mouse kidney M1 cells revealed that 24 h treatment with glycyrrhetinic acid did not affect the 11-HSD2 mRNA expression levels. Thus, in addition to its role as a competitive inhibitor of 11-HSD2, the chronic high dose of GA suppresses mRNA and protein expression of 11-HSD2 possibly via indirect mechanisms. These effects may explain the prolonged symptoms after cessation of GA administration in some pseudoaldosteronism patients.     

Cloning of chicken 11beta-hydroxysteroid dehydrogenase type 1 and its tissue distribution

11beta-Hydroxysteroid dehydrogenase type 1 (11HSD1) is an enzyme that interconverts active 11-hydroxy glucocorticoids (cortisol, corticosterone) and their inactive 11-oxo derivatives (cortisone, 11-dehydrocorticosterone). Although bidirectional, it is considered to operate in vivo as an 11-reductase that regenerates active glucocorticoids and thus amplifies their local activity in mammals. Here we report the cloning, characterization and tissue distribution of chicken 11HSD1 (ch11HSD1). Its cDNA predicts a protein of 300 amino acids that share 51-56% sequence identity with known mammalian 11HSD1 proteins, while in contrast to most mammals, ch11HSD1 contains only one N-linked glycosylation site. Analysis of the tissue distribution pattern by RT-PCR revealed that ch11HSD1 is expressed in a large variety of tissues, with high expression in the liver, kidney and intestine, and weak in the gonads, brain and heart. 11-Reductase activity has been found in the liver, kidney, intestine and gonads with low or almost zero activity in the brain and heart. These results provide evidence for a role of 11HSD1 as a tissue-specific regulator of glucocorticoid action in non-mammalian vertebrates and may serve as a suitable model for further analysis of 11HSD1 evolution in vertebrates.     

Localization of 17beta-hydroxysteroid dehydrogenase in Mycobacterium sp. VKM Ac-1815D mutant strain

The localization of mycobacterial 17β-hydroxysteroid dehydrogenase (17β-OH SDH) was studied using cell fractionation and cytochemical investigation. Mycobacterium sp. Et1 mutant strain derived from Mycobacterium sp. VKM Ac-1815D and characterized by increased 17β-OH SDH activity was used as a model organism.

Subcellular distribution study showed both soluble and membrane-bound forms of mycobacterial 17β-hydroxysteroid dehydrogenase. The cytochemical method based on a copper ferrocyanide procedure followed by electron microscopic visualization was applied in order to investigate the intracellular localization of bacterial 17β-OH SDH in more detail. The enzyme was found to be located in the peripheral cytoplasmic zone adjoining the cytoplasmic membrane (CM). 17β-OH SDH was loosely membrane bound and easily released into the environment under the cell integrity failure.     

Mammalian lignans and genistein decrease the activities of aromatase and 17beta-hydroxysteroid dehydrogenase in MCF-7 cells

Estrogen plays a major role in breast cancer development and progression. Breast tissue and cell lines contain the necessary enzymes for estrogen synthesis, including aromatase and 17β-hydroxysteroid dehydrogenase (17β-HSD). These enzymes can influence tissue exposure to estrogen and therefore have become targets for breast cancer treatment and prevention. This study determined whether the isoflavone genistein (GEN) and the mammalian lignans enterolactone (EL) and enterodiol (ED) would inhibit the activity of aromatase and 17β-HSD type 1 in MCF-7 cancer cells, thereby decreasing the amount of estradiol (E2) produced and consequently cell proliferation. Results showed that 10 μM EL, ED and GEN significantly decreased the amount of estrone (E1) produced via the aromatase pathway by 37%, 81% and 70%, respectively. Regarding 17β-HSD type 1, 50 μM EL and GEN maximally inhibited E2 production by 84% and 59%, respectively. The reduction in E1 and E2 production by EL and the reduction in E2 production by GEN were significantly related to a reduction in MCF-7 cell proliferation. 4-Hydroxyandrostene-3,17-dione (50 μM) did not inhibit aromatase but inhibited the conversion of E1 to E2 by 78%, suggesting that it is a 17β-HSD type 1 inhibitor. In conclusion, modulation of local E2 synthesis is one potential mechanism through which ED, EL and GEN may protect against breast cancer.     

Androgenic and estrogenic 17beta-hydroxysteroid dehydrogenase/17-ketosteroid reductase in human ovarian epithelial tumors: evidence for the type 1, 2 and 5 isoforms

17β-Hydroxysteroid dehydrogenase/17-ketosteroid reductases (17HSD/KSR) play a key role in regulating steroid receptor occupancy in normal tissues and tumors. Although 17HSD/KSR activity has been detected in ovarian epithelial tumors, our understanding of which isoforms are present and their potential for steroid metabolism is limited. In this investigation, 17HSD/KSR activity from a series of ovarian epithelial tumors was assayed in cytosol and microsomes under conditions which differentiate between isoforms. Inhibition studies were used to further characterize the steroid specificities of isoforms in the two subcellular fractions. Activity varied widely between tumors of the same histopathologic classification. The highest levels of activity were observed in mucinous tumors. Michaelis constants, maximum velocities, estradiol-17β/testosterone (E₂/T) activity ratios and inhibition patterns were consistent with a predominance of microsomal 17HSD/KSR2 and cytosolic 17HSD/KSR5, isoforms reactive with both E₂ and T, with evidence of estrogenic 17HSD/KSR1 in cytosol from some samples. In tumors where activity and mRNA expression were both characterized, Northern blots, PCR and sequence analysis indicated 17HSD/KSR5 was the predominant isoform. The presence of 17HSD/KSR5, which also has both 3-HSD/KSR and 20HSD/KSR activity, and 17HSD/KSR2 which also has 20-HSD activity, could influence not only estrogen and androgen binding but progesterone receptor occupancy, as well, in receptor-containing tumors.     

11beta-hydroxysteroid dehydrogenases,cell proliferation and malignancy

The enzymes 11β-hydroxysteroid dehydrogenase type 1 and 2 (11β-HSD1 and 2) have well-defined roles in the tissue-specific metabolism of glucocorticoids which underpin key endocrine mechanisms such as adipocyte differentiation (11β-HSD1) and mineralocorticoid action (11β-HSD2). However, in recent studies we have shown that the effects of 11β-HSD1 and 2 are not restricted to distinct tissue-specific hormonal functions. Studies of normal fetal and adult tissues, as well as their tumor equivalents, have shown a further dichotomy in 11β-HSD expression and activity. Specifically, most normal glucocorticoid receptor (GR)-rich tissues such as adipose tissue, bone, and pituitary cells express 11β-HSD1, whereas their fetal equivalents and tumors express 11β-HSD2. We have therefore postulated that the ability of 11β-HSD1 to generate cortisol acts as an autocrine anti-proliferative, pro-differentiation stimulus in normal adult tissues. In contrast, the cortisol-inactivating properties of 11β-HSD2 lead to pro-proliferative effects, particularly in tumors. This proposal is supported by experiments in vitro which have demonstrated divergent effects of 11β-HSD1 and 2 on cell proliferation. Current studies are aimed at (1) characterizing the underlying mechanisms for a ‘switch’ in 11β-HSD isozyme expression in tumors; (2) defining the molecular targets for glucocorticoids as regulators of cell proliferation; (3) evaluating the potential for targeting glucocorticoid metabolism as therapy for some cancers. These and other issues are discussed in the present review.     

Characterization of human DHRS4: an inducible short-chain dehydrogenase/reductase enzyme with 3beta-hydroxysteroid dehydrogenase activity

Human DHRS4 is a peroxisomal member of the short-chain dehydrogenase/reductase superfamily, but its enzymatic properties, except for displaying NADP(H)-dependent retinol dehydrogenase/reductase activity, are unknown. We show that the human enzyme, a tetramer composed of 27 kDa subunits, is inactivated at low temperature without dissociation into subunits. The cold inactivation was prevented by a mutation of Thr177 with the corresponding residue, Asn, in cold-stable pig DHRS4, where this residue is hydrogen-bonded to Asn165 in a substrate-binding loop of other subunit. Human DHRS4 reduced various aromatic ketones and α-dicarbonyl compounds including cytotoxic 9,10-phenanthrenequinone. The overexpression of the peroxisomal enzyme in cultured cells did not increase the cytotoxicity of 9,10-phenanthrenequinone. While its activity towards all-trans-retinal was low, human DHRS4 efficiently reduced 3-keto-C₁₉/C₂₁-steroids into 3β-hydroxysteroids. The stereospecific conversion to 3β-hydroxysteroids was observed in endothelial cells transfected with vectors expressing the enzyme. The mRNA for the enzyme was ubiquitously expressed in human tissues and several cancer cells, and the enzyme in HepG2 cells was induced by peroxisome-proliferator-activated receptor α ligands. The results suggest a novel mechanism of cold inactivation and role of the inducible human DHRS4 in 3β-hydroxysteroid synthesis and xenobiotic carbonyl metabolism.     

Activin-A, but not inhibin, regulates 17β-hydroxysteroid dehydrogenase type 1 activity and expression in cultured rat granulosa cells

17β-Hydroxysteroid dehydrogenase type 1 (17HSD type 1) catalyzes the reduction of estrone (E₁) to biologically more active estradiol (E₂). In the present study, the effect of activin, inhibin, and follistatin on 17HSD activity and 17HSD type 1 expression in cultured, unluteinized rat granulosa cells was examined. Furthermore, the effects of these hormones on 17HSD type 1 expression were compared with the expression of P450 aromatase (P450arom). Rat granulosa cells were pre-incubated in serum-free media for 3 days, followed by a 2-day treatment with activin, inhibin, follistatin and 8-Br-cAMP. Activin in increasing concentrations appeared to effect a dose-dependent increase in 17HSD activity. In addition, increasing concentrations of activin also increased 17HSD type 1 mRNA expression. Addition of 8-Br-cAMP at concentrations of 0.25 and 1.5 mmol/l together with activin significantly augmented the stimulatory effects of activin alone in the cultured cells. Neither inhibin, nor follistatin, either alone or in combination with 8-Br-cAMP, had any notable effects on 17HSD activity and 17HSD type 1 expression. Preincubation of activin with increasing concentrations of follistatin significantly diminished the stimulatory effect of activin. In the presence of follistatin, activin did not significantly increase the 8-Br-cAMP-induced 17HSD activity and 17HSD type 1 expression. The culturing of granulosa cells in the presence or the absence of inhibin or follistatin with or without 8-Br-cAMP did not alter the effect of these peptides on P450arom expression in rat granulosa cells as judged by Northern blot analysis of total RNA. However, cAMP-induced P450arom expression was enhanced by activin treatment, except when follistatin was present. This is in line with the suggested role of follistatin as an activin-binding protein, which limits the bioavailability of activin to its membrane receptors. Thus, the results support the notion of a paracrine/autocrine role of activin in follicular steroidogenesis of growing follicles.     

Expression of cyclooxygenase 1 and 2 in the canine corpus luteum during diestrus

In the dog, unlike most other domestic animal species, corpus luteum (CL) life span is not affected by hysterectomy. Only in pregnant dogs, during the immediate prepartum decline of progesterone, does PGF2alpha clearly seem to act as an endogenous luteolytic agent. Whether endogenous PGF2alpha plays a role in the slow regression of the corpora lutea of the nonpregnant cycle is not known. To test for possible paracrine/autocrine effects of locally produced PGF2alpha, luteal expression of the key rate-limiting enzymes in prostaglandin biosynthesis, i.e. cyclooxygenase 1 and 2 (Cox1 and Cox2), was examined in dogs during diestrus, including the periods of CL formation, as well as early and late CL regression. Corpora lutea were collected by ovariohysterectomy from nonpregnant bitches 5, 15, 25, 35, 45 and 65 days after ovulation. On the mRNA-level, expression of Cox1 and Cox2 was tested by qualitative and quantitative, Real Time (Taq Man) RT-PCR; on the protein level, expression of Cox2 was studied by immunohistochemistry. The mRNA for Cox1 and Cox2 were detected at all stages of diestrus. Expression of Cox1 was lowest on Day 5 (ovulation = Day 0) and higher and nearly constant thereafter. Expression of Cox2-mRNA was distinctly cycle related and highest on Day 5; it decreased by Day 15 and remained constantly low until Day 65. Immunohistochemistry localized expression of Cox2 in the cytoplasm of luteal cells. Staining was restricted to Days 5 and 15, with stronger signals on Day 5. These data suggested that increased expression of Cox2 is associated with luteal growth and development and not luteal regression. Furthermore, the expression of Cox1 more likely reflected activity of a housekeeping gene.     

3beta-Hydroxysteroid dehydrogenase/5-ene-4-ene isomerase mRNA expression in rat brain: effect of pseudopregnancy and traumatic brain injury

Evidence that endogenous progesterone (PROG) is neuroprotective after traumatic brain injury (TBI) is supported by the findings that pseudopregnant female rats present less edema and achieve better functional recovery than do male rats. PROG in the nervous system may originate from steroidogenic glands or can be locally synthesized. 3β-Hydroxysteroid dehydrogenase/5-ene-4-ene isomerase (3β-HSD) is the key enzyme in the biosynthesis of PROG. In the present study, we investigated the effects of pseudopregnancy and TBI on brain 3β-HSD mRNA expression and on PROG levels. Twenty-four hours after bilateral contusion of the medial prefrontal cortex of rats, 3β-HSD mRNA expression was analyzed by in situ hybridization while PROG levels were measured by gas chromatography/mass spectrometry. Similar levels of 3β-HSD mRNA expression were observed in males and pseudopregnant females in the non-injured groups. At this time point, there was a significant decrease in the 3β-HSD mRNA expression in the contusion site within the frontal cortex in both males and pseudopregnant females. In all other regions analyzed, 3β-HSD mRNA expression was not affected by TBI and there was no difference between males and pseudopregnant females. The high decrease in the expression of the 3β-HSD mRNA in the lesion site 24 h after TBI suggests a possible decrease in locally synthesized PROG in lesion site without change in the other brain regions. This decrease has less impact in pseudopregnant females since they have high plasmatic and brain levels of PROG compared to males.     

Inhibition of human and rat 11beta-hydroxysteroid dehydrogenase type 1 by 18beta-glycyrrhetinic acid derivatives

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) plays an important role in regulating the cortisol availability to bind to corticosteroid receptors within specific tissue. Recent advances in understanding the molecular mechanisms of metabolic syndrome indicate that elevation of cortisol levels within specific tissues through the action of 11β-HSD1 could contribute to the pathogenesis of this disease. Therefore, selective inhibitors of 11β-HSD1 have been investigated as potential treatments for metabolic diseases, such as diabetes mellitus type 2 or obesity. Here we report the discovery and synthesis of some 18β-glycyrrhetinic acid (18β-GA) derivatives (2–5) and their inhibitory activities against rat hepatic11β-HSD1 and rat renal 11β-HSD2. Once the selectivity over the rat type 2 enzyme was established, these compounds’ ability to inhibit human 11β-HSD1 was also evaluated using both radioimmunoassay (RIA) and homogeneous time resolved fluorescence (HTRF) methods. The 11-modified 18β-GA derivatives 2 and 3 with apparent selectivity for rat 11β-HSD1 showed a high percentage inhibition for human microsomal 11β-HSD1 at 10 μM and exhibited IC₅₀ values of 400 and 1100 nM, respectively. The side chain modified 18β-GA derivatives 4 and 5, although showing selectivity for rat 11β-HSD1 inhibited human microsomal 11β-HSD1 with IC₅₀ values in the low micromolar range.     

Δ53β hydroxysteroid dehydrogenase activity of the rat corpus luteum exhibits positive substrate-binding co-operativity: A continuous monitoring microdensitometric study with unfixed ovarian tissue sections

Δ⁵3β hydroxysteroid dehydrogenase activity transforms biologically inactive Δ⁵3β hydroxy steroids into the active Δ⁴3-keto products (e.g. pregnenolone to progesterone). Using a cytochemical procedure which allows for the continuous microdensitometric monitoring of an enzyme reaction as it proceeds and a well described cytochemical assay for Δ⁵3β HSD we have analysed the initial velocity rates (V_o) for dehydroepiandrosterone (DHEA) binding to this enzyme in regressing (i.e. 20α hydroxy steroid dehydrogenase positive) corpus luteum (CL) cells in unfixed tissue sections (5 μm) of the dioestrous and proestrous rat ovary. The results are mean ± S.E.M. The relationship between DHEA concentration (0 to 50 μM) and Δ⁵3β HSD activity in the dioestrous corpora lutea was sigmoidal and had an atypical 1/V_o versus 1/S plot, the x intercept being positive. Using a 1/V_o versus 1/S² plot the V_max was determined to be 1·0 ± 0·08 μmol min^?1 mg^?1 CL (n = 6). The Hill constant was 2·7 ± 0·02 (n = 6) suggesting a high degree of positive co-operativity for DHEA binding. The S concentration for half maximal activity was 17 ± 1 μmoles (n = 6). In the corpora lutea cells of the proestrous ovary, the V_max for DHEA transformation was unchanged (0·95 ± 0·04 μmol min^?1 mg^?1, n = 3) whilst the S_0·5 was significantly increased to 27 ± 0·1 (p < 0·01, n = 3). The Hill constant remained positive being 2·9 ± 0·2 (n = 3). NAD⁺ binding to 3β HSD in regressing corpora lutea of the proestrous ovary has been demonstrated previously to be hyperbolic and fit the classical Michaelis-Menten model.¹ Extending the analysis of NAD⁺ binding to the regressing corpus luteum of the dioestrous rat ovary revealed similar kinetic characteristics to that seen with the proestrous enzyme, the apparent V_max and K_m being 0·84 ± 0·04 μmol min^?1 mg^?1 CL (n = 3) and 27 ± 7 μmol 1^?1 (n = 3) respectively. The Hill constant was 1·1 ± 0·03 (n = 3), indicating no co-operativity of co-factor binding.     

3alpha/beta,20beta-hydroxysteroid dehydrogenase (porcine testicular carbonyl reductase) also has a cysteine residue that is involved in binding of cofactor NADPH

Besides residue of the catalytic triad that is conserved in the short-chain dehydrogenase/reductase (SDR) superfamily, a Cys side chain reportedly plays functional roles in NADP-dependent 15-hydroxyprostaglandin dehydrogenase and human carbonyl reductase (CR). The three-dimensional structure of porcine 3alpha/beta,20beta-hydroxysteroid dehydrogenase, also known as porcine testicular carbonyl reductase, demonstrates the proximity of the Cys 226 side chain to the bound NADP. However, no clear explanation with respect to the basis of the catalytic function of the Cys residue is yet available. By chemical modification, point mutation, and kinetic analysis, we determine that two Cys residues, Cys 149 and Cys 226, are involved in the enzyme activity. Furthermore, we found that pretreatment with NADP markedly protects the enzyme from inactivation by 4-(hydroxyl mercury) benzoic acid (4-HMB), thereby confirming that Cys 226 is involved in binding of the cofactor. On the basis of the tertiary structure of 3alpha/beta,20beta-HSD, the possible roles of Cys residues, especially that of Cys 226, in enzyme action and in the binding of cofactor NADPH are discussed.     

Novel non-steroidal inhibitors of human 11beta-hydroxysteroid dehydrogenase type 1

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) regulates glucocorticoid action at the pre-receptor stage by converting cortisone to cortisol. 11β-HSD1 is selectively expressed in many tissues including the liver and adipose tissue where metabolic events are important. Metabolic syndrome relates to a number of metabolic abnormalities and currently has a prevalence of >20% in adult Americans. 11β-HSD1 inhibitors are being investigated by many major pharmaceutical companies for type 2 diabetes and other abnormalities associated with metabolic syndrome. In this area of intense interest a number of structural types of 11β-HSD1 inhibitor have been identified. It is important to have an array of structural types as the physicochemical properties of the compounds will determine tissue distribution, HPA effects, and ultimately clinical utility. Here we report the discovery and synthesis of three structurally different series of novel 11β-HSD1 inhibitors that inhibit human 11β-HSD1 in the low micromolar range. Docking studies with 1–3 into the crystal structure of human 11β-HSD1 reveal how the molecules may interact with the enzyme and cofactor and give further scope for structure based drug design in the optimisation of these series.     

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 11β-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, 17β-estradiol strongly stimulates HSD1 mRNA expression (10-fold) and, in contrast, decreases by half the P450 aromatase expression. In men, 17β-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.