Inactive 11-dehydrocorticosterone Research Articles

Decreased 11β-hydroxysteroid dehydrogenase 1 in lungs of steroid receptor coactivator (Src)-1/-2 double-deficient fetal mice is caused by impaired glucocorticoid and cytokine signaling.

Our previous research revealed that steroid receptor coactivators (Src)-1 and -2 serve a critical cooperative role in production of parturition signals, surfactant protein A and platelet-activating factor, by the developing mouse fetal lung (MFL). To identify the global landscape of genes in MFL affected by Src-1/-2 double-deficiency, we conducted RNA-seq analysis of lungs from 18.5days post-coitum (dpc) Src-1-/- /-2-/- (dKO) vs. WT fetuses. One of the genes most highly downregulated (~4.8 fold) in Src-1/-2 dKO fetal lungs encodes 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which catalyzes conversion of inactive 11-dehydrocorticosterone to the glucocorticoid receptor (GR) ligand, corticosterone. Glucocorticoids were reported to upregulate 11β-HSD1 expression in various cell types via induction of C/EBP transcription factors. We observed that C/ebpα and C/ebpβ mRNA and protein were markedly reduced in Src-1/-2 double-deficient (Src-1/-2d/d ) fetal lungs, compared to WT. Moreover, glucocorticoid induction of 11β-hsd1, C/ebpα and C/ebpβ in cultured MFL epithelial cells was prevented by the SRC family inhibitor, SI-2. Cytokines also contribute to the induction of 11β-HSD1. Expression of IL-1β and TNFα, which dramatically increased toward term in lungs of WT fetuses, was markedly reduced in Src-1/-2d/d fetal lungs. Our collective findings suggest that impaired lung development and surfactant synthesis in Src-1/-2d/d fetuses are likely caused, in part, by decreased GR and cytokine induction of C/EBP and NF-κB transcription factors. This results in reduced 11β-HSD1 expression and glucocorticoid signaling within the fetal lung, causing a break in the glucocorticoid-induced positive feedforward loop.

MON-005 Inhibition of Glucocorticoid Signaling in SRC-1/-2 Double-Deficient Mice Results in Impaired Lung Maturation and Delayed Parturition

The mechanisms that lead to the initiation of parturition are incompletely defined. Parturition timing is mediated by signals from both mother and fetus. Our previous findings using mice that were double-deficient in steroid receptor coactivators (Src)1 and 2 (Src-1/-2d/d) suggest that the fetus signals its mother when it is ready to be born through fetal lung production of surfactant components, surfactant protein A (SP-A) and platelet-activating factor (PAF). Notably, mice that are double knockout for Src-1/-2 die at birth of respiratory distress, due to decreased surfactant lipoprotein production. Intriguingly, we observed that wild-type (WT) mothers carrying Src-1/-2d/d fetuses manifested a ~38 h delay in parturition compared to WT mothers carrying WT fetuses. This was associated with decreased production of SP-A and PAF by the Src-1/-2d/d fetal lungs. Our findings suggested that these effects of Src-1/-2d/d were caused by impaired glucocorticoid receptor (GR) transcriptional activity in fetal lung cells. To identify other genes in fetal lung that were affected by Src-1/-2d/d, we conducted RNA-seq analysis of lungs from 18.5 days post-coitum Src-1/-2d/dvs. WT fetuses. We observed that one of the genes most highly downregulated in Src-1/-2d/d fetal lungs was 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). 11β-HSD1 catalyzes the conversion of inactive cortisone or 11-dehydrocorticosterone into active cortisol or corticosterone, respectively, which are ligands for the glucocorticoid receptor (GR). We validated the RNA-seq results by RT-qPCR and immunoblotting and observed a striking reduction of 11β-HSD1 mRNA and protein in lungs of Src-1/2d/d fetuses, compared to WT. Others observed that glucocorticoids potently increased 11β-HSD1 expression in various cell types via activation of transcription factors C/EBPα and C/EBPβ, providing a potential positive feed-forward loop. Notably, we observed that C/EBPα and C/EBPβ mRNA and protein were markedly reduced in Src-1/-2d/d fetal lungs, compared to WT. Deletion of the Cebpa gene in respiratory epithelium of fetal mice caused respiratory failure at birth due to surfactant lipid and protein deficiency. This was associated with increased expression of TGF-β2, which inhibits fetal lung maturation. Notably, we observed that expression of TGF-β2 and TGF-β3 were increased in Src-1/-2d/d fetal lungs. Thus, impaired lung development, surfactant synthesis and delayed parturition in Src-1/-2d/d fetuses are likely caused by decreased 11β-HSD1 and GR signaling, resulting in decreased C/EBPα/β expression and increased TGF-β signaling.

T-cell autonomous death induced by regeneration of inert glucocorticoid metabolites

Glucocorticoids (GC) are essential regulators of T-cell development and function. Activation of the immune system increases systemic adrenal-derived GC levels which downregulate immune activity as part of a negative feedback control system. Increasing evidence shows, however, that GC can also be derived from extra-adrenal sources such as the thymus or intestine, thus providing local control of GC-mediated effects. The thymus reportedly produces GC, but whether thymic epithelial cells or thymocytes produce GC acting either in an autocrine or paracrine fashion is not clear. We studied the expression of two main enzymes involved in de novo GC synthesis, CYP11A1 and CYP11B1, as well as the expression and activity of HSD11B1, an enzyme catalyzing interconversion of inert GC metabolites with active GC. While we found no evidence of de novo GC synthesis in both thymocytes and peripheral T cells, abundant regeneration of GC from the inactive metabolite 11-dehydrocorticosterone was detectable. Irrespective of their maturation stage, T cells that produced GC in this manner undergo autonomous cell death as this was blocked when glucocorticoid receptor-deficient T cells were treated with GC metabolites. These results indicate that both immature and mature T cells possess the capacity to undergo apoptosis in response to intrinsically generated GC. Consequently, positive selection of thymocytes, as well as survival of peripheral T cells may depend on TCR-induced escape of otherwise HSD11B1-driven autonomous T-cell death.

Mineralocorticoid and glucocorticoid receptors differentially regulate NF-kappaB activity and pro-inflammatory cytokine production in murine BV-2 microglial cells

BackgroundMicroglia, the resident macrophage-like cells in the brain, regulate innate immune responses in the CNS to protect neurons. However, excessive activation of microglia contributes to neurodegenerative diseases. Corticosteroids are potent modulators of inflammation and mediate their effects by binding to mineralocorticoid receptors (MR) and glucocorticoid receptors (GR). Here, the coordinated activities of GR and MR on the modulation of the nuclear factor-κB (NF-κB) pathway in murine BV-2 microglial cells were studied.MethodsBV-2 cells were treated with different corticosteroids in the presence or absence of MR and GR antagonists. The impact of the glucocorticoid-activating enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) was determined by incubating cells with 11-dehydrocorticosterone, with or without selective inhibitors. Expression of interleukin-6 (IL-6), tumor necrosis factor receptor 2 (TNFR2), and 11β-HSD1 mRNA was analyzed by RT-PCR and IL-6 protein expression by ELISA. NF-κB activation and translocation upon treatment with various corticosteroids were visualized by western blotting, immunofluorescence microscopy, and translocation assays.ResultsGR and MR differentially regulate NF-κB activation and neuroinflammatory parameters in BV-2 cells. By converting inactive 11-dehydrocorticosterone to active corticosterone, 11β-HSD1 essentially modulates the coordinated action of GR and MR. Biphasic effects were observed for 11-dehydrocorticosterone and corticosterone, with an MR-dependent potentiation of IL-6 and tumor necrosis factor-α (TNF-α) expression and NF-κB activation at low/moderate concentrations and a GR-dependent suppression at high concentrations. The respective effects were confirmed using the MR ligand aldosterone and the antagonist spironolactone as well as the GR ligand dexamethasone and the antagonist RU-486. NF-κB activation could be blocked by spironolactone and the inhibitor of NF-κB translocation Cay-10512. Moreover, an increased expression of TNFR2 was observed upon treatment with 11-dehydrocorticosterone and aldosterone, which was reversed by 11β-HSD1 inhibitors and/or spironolactone and Cay-10512.ConclusionsA tightly coordinated GR and MR activity regulates the NF-κB pathway and the control of inflammatory mediators in microglia cells. The balance of GR and MR activity is locally modulated by the action of 11β-HSD1, which is upregulated by pro-inflammatory mediators and may represent an important feedback mechanism involved in resolution of inflammation.

Hyperglycemia Induces the Variations of 11β-Hydroxysteroid Dehydrogenase Type 1 and Peroxisome Proliferator-Activated Receptor-γExpression in Hippocampus and Hypothalamus of Diabetic Rats

In this paper, we first observed that there were differences in expressions of 11β-HSD1 and PPAR-γ, in hippocampi and hypothalami, among constant hyperglycemia group, control group and the fluctuant glycemia group, using Immunohistochemical analysis. However, whether in expression o f 11β-HSD1 or PPAR-γ, there were no statistic differences between the control group or the fluctuant glycemia group. So, we removed the fluctuant glycemia group, retaining only constant hyperglycemia group and control group, being fed for 8 weeks. After 8 weeks of induction, 11β-HSD1 expression increased and PPAR-γ expression decreased in the constant hyperglycemia group compared with control group, both in hippocampi and hypothalami, by Western Blot. The constant hyperglycemia group also showed impaired cognition in MORRIS watermaze, lower serum corticosterone level, and higher Serum ACTH concentration after 8 weeks. We inferred that the cognition impairment may be related to the abnormal expression of 11β-HSD1 and PPAR-γ in central nerves system. As for 11β-HSD1 is a regulating enzyme, converting the inactive 11-dehydrocorticosterone into the active glucocorticoid corticosterone, thus amplifying GC action in local tissues. It is also well known that high local GC levels can affect the cognitive function. In addition, PPAR-a protective receptor, which is related to cognition.

11β-Hydroxysteroid Dehydrogenase Type 1, But Not Type 2, Deficiency Worsens Acute Inflammation and Experimental Arthritis in Mice

Glucocorticoids profoundly influence immune responses, and synthetic glucocorticoids are widely used clinically for their potent antiinflammatory effects. Endogenous glucocorticoid action is modulated by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD). In vivo, 11β-HSD1 catalyzes the reduction of inactive cortisone or 11-dehydrocorticosterone into active cortisol or corticosterone, respectively, thereby increasing intracellular glucocorticoid levels. 11β-HSD2 catalyzes the reverse reaction, inactivating intracellular glucocorticoids. Both enzymes have been postulated to modulate inflammatory responses. In the K/BxN serum transfer model of arthritis, 11β-HSD1-deficient mice showed earlier onset and slower resolution of inflammation than wild-type controls, with greater exostoses in periarticular bone and, uniquely, ganglion cysts, consistent with greater inflammation. In contrast, K/BxN serum arthritis was unaffected by 11β-HSD2 deficiency. In a distinct model of inflammation, thioglycollate-induced sterile peritonitis, 11β-HSD1-deficient mice had more inflammatory cells in the peritoneum, but again 11β-HSD2-deficient mice did not differ from controls. Additionally, compared with control mice, 11β-HSD1-deficient mice showed greater numbers of inflammatory cells in pleural lavages in carrageenan-induced pleurisy with lung pathology consistent with slower resolution. These data suggest that 11β-HSD1 limits acute inflammation. In contrast, 11β-HSD2 plays no role in acute inflammatory responses in mice. Regulation of local 11β-HSD1 expression and/or delivery of substrate may afford a novel approach for antiinflammatory therapy.

Effects of antisense-mediated inhibition of 11β-hydroxysteroid dehydrogenase type 1 on hepatic lipid metabolism

11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) converts inactive 11-keto derivatives to active glucocorticoids within tissues and may play a role in the metabolic syndrome (MS). We used an antisense oligonucleotide (ASO) to knock down 11β-HSD1 in livers of C57BL/6J mice consuming a Western-type diet (WTD). 11β-HSD1 ASO-treated mice consumed less food, so we compared them to ad libitum-fed mice and to food-matched mice receiving control ASO. Knockdown of 11β-HSD1 directly protected mice from WTD-induced steatosis and dyslipidemia by reducing synthesis and secretion of triglyceride (TG) and increasing hepatic fatty acid oxidation. These changes in hepatic and plasma lipids were not associated with reductions in genes involved in de novo lipogenesis. However, protein levels of both sterol regulatory element-binding protein (SREBP) 1 and fatty acid synthase were significantly reduced in mice treated with 11β-HSD1 ASO. There was no change in hepatic secretion of apolipoprotein (apo)B, indicating assembly and secretion of smaller apoB-containing lipoproteins by the liver in the 11β-HSD1-treated mice. Our results indicate that inhibition of 11β-HSD1 by ASO treatment of WTD-fed mice resulted in improved plasma and hepatic lipid levels, reduced lipogenesis by posttranslational regulation, and secretion of similar numbers of apoB-containing lipoproteins containing less TG per particle.

7α-Hydroxytestosterone Affects 11β-Hydroxysteroid Dehydrogenase 1 Direction in Rat Leydig Cells

The cytochrome P450 2A1 (CYP2A1) is a P450 enzyme that catalyzes the metabolism of testosterone. CYP2A1 has been reported to be present in rat testis. However, its developmental changes and function have not been well characterized. The purpose of this study was to measure the abundance of CYP2A1 (Cyp2a1) mRNA in the developing rat testis and Leydig cells and examine the effects of its product, 7 alpha-hydroxytestosterone (7HT), on an important enzyme, 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) that interconverts active corticosterone and inactive 11-dehydrocorticosterone. As detected by real-time PCR, Cyp2a1 was found to be present exclusively in the Leydig cell. CYP2A1 activity in adult Leydig cells was 5-fold higher than those in progenitor or immature Leydig cells. 7HT competitively suppressed 11 beta-HSD1 oxidase and reductase activities in rat testis microsome with inhibitory constant of 1.2 and 2.9 mum, respectively. In intact Leydig cells, 7HT did not inhibit 11 beta-HSD1 reductase activity, but it stimulated its reductase activity. Thus, at 100 nm and higher concentrations, 7HT significantly switched 11 beta-HSD1 oxidoreductase activities toward reductase. The present data shows that 7HT, the product formed by CYP2A1 from testosterone, regulates the direction of 11 beta-HSD1 activity in rat Leydig cells.

Renal medullary 11β-hydroxysteroid dehydrogenase type 1 in Dahl salt-sensitive hypertension

The Dahl salt-sensitive rat is a widely used model of human salt-sensitive forms of hypertension. The kidney plays an important role in the pathogenesis of Dahl salt-sensitive hypertension, but the molecular mechanisms involved remain a subject of intensive investigation. Gene expression profiling studies suggested that 11 beta-hydroxysteroid dehydrogenase type 1 might be dysregulated in the renal medulla of Dahl salt-sensitive rats. Additional analysis confirmed that renal medullary expression of 11 beta-hydroxysteroid dehydrogenase type 1 was downregulated by a high-salt diet in SS-13BN rats, a consomic rat strain with reduced blood pressure salt sensitivity, but not in Dahl salt-sensitive rats. 11 beta-Hydroxysteroid dehydrogenase type 1 is known to convert inactive 11-dehydrocorticosterone to active corticosterone. The urinary corticosterone/11-dehydrocorticosterone ratio as well as urinary excretion of corticosterone was higher in Dahl salt-sensitive rats than in SS-13BN rats. Knockdown of renal medullary 11 beta-hydroxysteroid dehydrogenase type 1 with small-interfering RNA attenuated the early phase of salt-induced hypertension in Dahl salt-sensitive rats and reduced urinary excretion of corticosterone. Knockdown of 11 beta-hydroxysteroid dehydrogenase type 1 did not affect blood pressure in SS-13BN rats. Long-term attenuation of salt-induced hypertension was achieved with small hairpin RNA targeting renal medullary 11 beta-hydroxysteroid dehydrogenase type 1. In summary, we have demonstrated that suppression of 11 beta-hydroxysteroid dehydrogenase type 1 expression in the renal medulla attenuates salt-induced hypertension in Dahl salt-sensitive rats.

Hexose-6-Phosphate Dehydrogenase and 11β-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.

Localization and glucocorticoid regulation of 11β-hydroxysteroid dehydrogenase type 1 mRNA in the male mouse forebrain

The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) converts the inactive 11-dehydrocorticosterone into the active glucocorticoid corticosterone. There is accumulating evidence indicating widespread expression of 11β-HSD1 in the brain. However, there is little information about regulation of 11β-HSD1 expression in this tissue. Using in situ hybridization involving use of 35S-labeled cRNA probe, we have studied the distribution of cells expressing 11β-HSD1 mRNA in the male mouse forebrain as well as the effects of adrenalectomy (ADX) and acute administration of corticosterone (3 and 24 h) on 11β-HSD1 mRNA levels. Cells expressing 11β-HSD1 mRNA were mostly detected in the cerebral cortex, hippocampus, amygdala and medial preoptic area, with the highest expression in the cerebral cortex (retrosplenial granular area) and hippocampus (CA3 and granular layer of the gyrus dentatus). Seven days following ADX, 11β-HSD mRNA levels were increased by 50% in the gyrus dentatus, by 100% in the CA3 area, and 105% in the cerebral cortex. Administration of corticosterone to ADX mice induced a significant decrease in mRNA, in both the hippocampus and cerebral cortex so that, at the 24 h time interval, the levels were similar to those observed in intact mice. These results clearly indicate that circulating corticosterone is downregulating the expression of 11β-HSD1 mRNA in the two forebrain areas studied. This downregulation might contribute to maintain low intracellular corticosterone levels in central regions and then prevent the deleterious effects induced by high glucocorticoid levels.

Intestinal inflammation modulates expression of 11β-hydroxysteroid dehydrogenase in murine gut

The effect of glucocorticoids is controlled at the pre-receptor level by the activity of 11beta-hydroxysteroid dehydrogenase (11HSD). The isoform 11HSD1 is an NADP+ -dependent oxidoreductase, usually reductase, that amplifies the action of glucocorticoids due to reduction of the biologically inactive 11-oxo derivatives cortisone and 11-dehydrocorticosterone to cortisol and corticosterone. The NAD+ -dependent isoform (11HSD2) is an oxidase that restrains the effect of hormones due to 11beta-oxidation of cortisol and corticosterone to their 11-oxo derivatives. Although the immunosuppressive and anti-inflammatory effects of glucocorticoids are well known, the relationship between inflammation and local metabolism of glucocorticoids is not well understood. In this study, we demonstrated that colitis induced by dextran sulfate sodium modulates colonic 11HSD1. Experimentally induced intestinal inflammation stimulated colonic NADP+ -dependent but not NAD+ -dependent 11HSD activity. Colonic 11HSD1 mRNA was increased, whereas 11HSD2 mRNA was not changed. Additional parallel studies revealed a similar pattern of 11HSD1 mRNA induction in mesenteric lymph nodes and intestinal intraepithelial lymphocytes, but not in spleen and peritoneal macrophages. These data suggest that inflammation modulates local metabolism of glucocorticoid and support the notion that pre-receptor regulation of endogenous corticosteroids might play a role in inflammatory processes.

Liver X Receptor Agonist T0901317 Inhibition of Glucocorticoid Receptor Expression in Hepatocytes May Contribute to the Amelioration of Diabetic Syndrome indb/dbMice

The glucocorticoid receptor (GR) is a crucial target gene for glucocorticoid-induced insulin resistance and hepatic gluconeogenesis linked to the development of type 2 diabetes. The liver X receptors (LXRs) are nuclear receptors that play an important role in the regulation of the metabolic gene linked to carbohydrate homeostasis. To assess the tissue-specific interaction of LXR with GR in the development of type 2 diabetes, we examined the possible effect of LXR agonist T0901317 on GR gene expression in vivo and in vitro in hepatocytes from db/db mice (a model of type 2 diabetes). Chronic ligand activation of LXR by a synthetic LXR T0901317 markedly decreased the expression of both GR mRNA and its protein in liver and improved the phenotype of type 2 diabetes in obese db/db mice. Suppression of hepatic GR expression was correlated with reduced levels of glucose and corresponded to the inhibition of phosphoenolpyruvate carboxykinase mRNA and 11beta-hydroxysteroid dehydrogenase type 1-mediated synthesis of active corticosterone from inactive 11-dehydrocorticosterone in liver. Treatment of db/db mouse primary hepatocytes with T0901317 resulted in dramatic suppression of GR mRNA and required ongoing protein synthesis. Addition of T0901317 to primary hepatocytes also suppressed the expression of both 11beta-hydroxysteroid dehydrogenase type 1 and phosphoenolpyruvate carboxykinase. These findings suggest that some of antidiabetic actions of LXR agonist T0901317 may be mediated, at least in part, through the suppression of hepatic GR gene expression.

The Mineralocorticoid Receptor-How to Get Away with Promiscuity: Evolution of Hormone-Receptor Complexity by Molecular Exploitation. Science 312: 97-101, 2006.

The Mineralocorticoid Receptor-How to Get Away with Promiscuity: Evolution of Hormone-Receptor Complexity by Molecular Exploitation. Science 312: 97-101, 2006.

Increased Glucocorticoid Receptor and 11β-Hydroxysteroid Dehydrogenase Type 1 Expression in Hepatocytes May Contribute to the Phenotype of Type 2 Diabetes in db/db Mice

Excess tissue glucocorticoid action may contribute to the hyperglycemia and insulin resistance associated with type 2 diabetes, but the associated mechanisms are poorly understood. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts inactive 11-dehydrocorticosterone into active corticosterone, thus amplifying glucocorticoid receptor-mediated tissue glucocorticoid action, particularly in the liver. To examine the role of tissue glucocorticoid action in type 2 diabetes, we analyzed expression of glucocorticoid receptor and 11beta-HSD1 and their regulation by endogenous hormones in vivo and in vitro in hepatocytes from db/db mice (a model of type 2 diabetes). We observed positive relations between expression of both glucocorticoid receptor and 11beta-HSD1 in liver and insulin sensitivity and expression of PEPCK mRNA in db/db mice and db/+ controls. Increased expression of glucocorticoid receptor and 11beta-HSD1 in the liver of db/db mice was correlated with elevated circulating levels of corticosterone, insulin, and blood glu-cose. Treatment of db/db mice with glucocorticoid antagonist RU486 reversed the increases in the expression of glucocorticoid receptor and 11beta-HSD1 within the liver and attenuated the phenotype of type 2 diabetes. Addition of corticosterone to db/db mouse primary hepatocytes activated expression of glucocorticoid receptor, 11beta-HSD1, and PEPCK, and these effects were abolished by RU486. Incubation of primary hepatocytes with increasing concentrations of glucose caused dose-dependent increases in glucocorticoid receptor and 11beta-HSD1 expression, whereas insulin did not affect the expression of 11beta-HSD1 and glucocorticoid receptor in primary hepatocytes. These findings suggest that activation of glucocorticoid receptor and 11beta-HSD1 expression within the liver may contribute to the development of type 2 diabetes in db/db mice.

Regulation of 11β‐hydroxysteroid dehydrogenase type 1 and glucose‐stimulated insulin secretion in pancreatic islets of Langerhans

In rodents, the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts inactive 11-dehydrocorticosterone (DHC) into active corticosterone. The mRNA and activity of 11beta-HSD1 have been shown to be present in batch-incubated pancreatic islets from the ob/ob mouse. In other tissues, 11beta-HSD1 expression has been demonstrated to be regulated by glucocorticoids. In the present study, the influence of DHC on 11beta-HSD1 levels and glucose-induced changes in insulin secretion were studied in pancreatic islets isolated from the ob/ob mouse. Western blotting with antiserum for 11beta-HSD1 verified the presence of 11beta-HSD1 in islets from obese ob/ob and normal C57BL/6J mice. Insulin secretion was determined by perifusing islets and assaying the perifusate with ELISA. Islets from the ob/ob mouse contained almost twofold more 11beta-HSD1 protein than islets from the C57BL/6J mouse. When islets from ob/ob mice were cultured with 50 nM DHC, the 11beta-HSD1 levels doubled compared with islets cultured in the absence of DHC. Selective inhibition of 11beta-HSD1 attenuated DHC-induced increase in 11beta-HSD1 levels, as did an antagonist of the glucocorticoid receptor. In individually perifused ob/ob mouse islets, early and late phases of glucose-stimulated insulin secretion (GSIS) were dose-dependently inhibited by 5, 50 and 500 nM DHC. Whereas inclusion of 11beta-HSD1 inhibitors restored, addition of the glucocorticoid receptor antagonist attenuated the DHC-mediated inhibition of GSIS. Levels of 11beta-HSD1 in islets from ob/ob mice are positively regulated by DHC and could be lowered by a selective 11beta-HSD1 inhibitor and a glucocorticoid receptor antagonist. Increased levels of 11beta-HSD1 were associated with impaired GSIS.

Postnatal development of 11beta-hydroxysteroid dehydrogenase type 1 in the rat hippocampus.

Glucocorticoids (GCs) have important actions in the hippocampus of the brain, where their access to glucocorticoid receptor (GR) is increased by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). 11beta-HSD1 converts biologically inactive 11-dehydrocorticosterone into active corticosterone. However, the postnatal development of 11beta-HSD1 in the hippocampus is not properly understood. In this study, the postnatal distribution and development of 11beta-HSD1 in the hippocampus of the rat brain was studied with immunohistochemistry and Western blot analysis. Results showed that abundant 11beta-HSD1 immunoreactive substance (ir-11beta-HSD1) was present in the hippocampus. There were homogeneous distributions of 11beta-HSD1 in the hippocampal CA1, CA2, CA3, CA4 regions and the dentate gyrus at postnatal days 1, 3, and 7. Interestingly, the developmental distribution of GR in the hippocampus followed the same pattern as 11beta-HSD1. Western blot analysis demonstrated that a higher level of expression of 11beta-HSD1 in the hippocampus was found in the first 2 weeks of life. The expressions of 11beta-HSD1 started to drop to adult levels at about postnatal day 15 both in the hippocampus and in other brain areas. These results suggest that the higher expression of 11beta-HSD1 in the neonatal hippocampus may be important for the maturation of the central nervous system mediated by GCs through GR.

11Beta-hydroxysteroid dehydrogenase 1 transforms 11-dehydrocorticosterone into transcriptionally active glucocorticoid in neonatal rat heart.

The ability of cells to directly respond to glucocorticoids and aldosterone is a function of GR and MR expression, and coexpression of 11beta-hydroxysteroid dehydrogenases (11betaHSDs), which convert glucocorticoids and their 11-ketometabolites into either receptor inactive or active derivatives. The aim of the present study was to determine the cellular expression of GR, MR, 11betaHSD1, and 11betaHSD2 in neonatal rat heart and determine the role these enzymes play in modulating glucocorticoid and aldosterone action. Ribonuclease protection analysis and steroid binding assays showed that GR is expressed in both cardiac myocytes and fibroblasts, whereas MR is expressed only in myocytes. 11betaHSD2 was not detected in cardiac cells, but 11betaHSD1 was expressed at high levels in both cardiac myocytes and fibroblasts. Enzyme activity studies demonstrated that 11betaHSD1 acted as a reductase only, converting biologically inactive 11-dehydrocorticosterone to corticosterone, which then stimulated serum and glucocorticoid-induced kinase gene transcription via GR. In both cardiac myocytes and fibroblasts, aldosterone stimulated serum and glucocorticoid-induced kinase gene expression exclusively via GR, but not MR, indicating that aldosterone can have glucocorticoid-like actions in heart. The ability of cardiac cells to use both circulating corticosterone and 11-dehydrocorticosterone as a source of glucocorticoid suggests that the heart is under tonic glucocorticoid control, implying that glucocorticoids play important homeostatic roles in the heart.

Cortisol-Secreting Adrenal Adenomas Express 11β-Hydroxysteroid Dehydrogenase Type-2 Gene yet Possess Low 11β-HSD2 Activity

Background11β-hydroxysteroid dehydrogenase Type-2 (11β-HSD2) is an unidirectional enzyme that catalyzes the conversion of glucocorticoid hormones cortisol and corticosterone (B) into their corresponding inactive forms, cortisone, and 11-dehydrocorticosterone (DH-B). We have...

11beta-hydroxysteroid dehydrogenase and corticosteroid action in lyon hypertensive rats.

Adrenocorticosteroid activity in Lyon hypertensive (LH) and low blood pressure (LL) rat strains differ in several respects. Abnormal activity of 11beta-hydroxysteroid dehydrogenase enzymes (11beta-HSD1 and 11beta-HSD2), which interconvert corticosterone and inactive 11-dehydrocorticosterone, might contribute to the LH phenotype by regulating corticosteroid hormone access to receptors. 11beta-HSD2 (expressed in kidney but not liver) prevents endogenous glucocorticoids from binding to mineralocorticoid receptors. 11beta-HSD1 (expressed in liver and kidney) favors active glucocorticoid formation from 11-dehydrocorticosterone. 11beta-HSD properties in LH and LL have been compared by several approaches: (1) 11betaHSD activities have been measured in vitro as corticosterone dehydrogenation and in vivo as interconversion of injected cortisol and cortisone; (2) the effects of cortisol and cortisone on urine electrolytes and volume have been measured; and (3) 11beta-HSD mRNA expression has been measured by in situ hybridization. 11beta-HSD2 enzyme activities in LH and LL rats were similar and urinary cortisone:cortisol ratios were not different after cortisol injection. Cortisol caused a natriuresis and kaliuresis in both strains, with a slightly reduced response in LH rats. Renal 11beta-HSD2 mRNA expression was slightly lower in LH rats. 11beta-HSD1 was less active in LH than LL rats: enzyme activities were lower in tissue extracts; urinary cortisone:cortisol was lower in LL rats after cortisone injections; cortisone increased urine volume in LL but not LH rats; and mRNA levels tended to be lower in LH tissues. We conclude that 11beta-HSD1 is impaired in LH rats. The LH phenotype of heavier adrenals, raised corticosterone, and reduced thymus weight is similar to that described for 11beta-HSD1 knockout mice.