Short- and long-term glucocorticoid treatment enhances insulin signalling in human subcutaneous adipose tissue

BACKGROUND: Endogenous or exogenous glucocorticoid (GC) excess (Cushing's syndrome) is characterized by increased adiposity and insulin resistance. Although GCs cause global insulin resistance in vivo, we have previously shown that GCs are able to augment insulin action in human adipose tissue, contrasting with their action in skeletal muscle. Cushing's syndrome develops following chronic GC exposure and, in addition, is a state of hyperinsulinemia. OBJECTIVES: We have therefore compared the impact of short- (24 h) and long-term (7 days) GC administration on insulin signalling in differentiated human adipocytes in the presence of low or high concentrations of insulin. RESULTS: Both short- (24 h) and long-term (7 days) treatment of chub-s7 cells with dexamethasone (Dex) (0.5 μM) increased insulin-stimulated pTyr612IRS1 and pSer473akt/PKB, consistent with insulin sensitization. Chronic high-dose insulin treatment induced insulin resistance in chub-s7 cells. However, treatment with both high-dose insulin and Dex in combination still caused insulin sensitization. CONCLUSIONS: In this human subcutaneous adipocyte cell line, prolonged GC exposure, even in the presence of high insulin concentrations, is able to cause insulin sensitization. We suggest that this is an important mechanism driving adipogenesis and contributes to the obese phenotype of patients with Cushing's syndrome

Impaired Glucose Tolerance and Insulin Resistance Are Associated With Increased Adipose 11β-Hydroxysteroid Dehydrogenase Type 1 Expression and Elevated Hepatic 5α-Reductase Activity

OBJECTIVE—The precise molecular mechanisms contributing to the development of insulin resistance, impaired glucose tolerance (IGT), and type 2 diabetes are largely unknown. Altered endogenous glucocorticoid metabolism, including 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which generates active cortisol from cortisone, and 5α-reductase (5αR), which inactivates cortisol, has been implicated

Regulation of Lipogenesis by Glucocorticoids and Insulin in Human Adipose Tissue

Patients with glucocorticoid (GC) excess, Cushing's syndrome, develop a classic phenotype characterized by central obesity and insulin resistance. GCs are known to increase the release of fatty acids from adipose, by stimulating lipolysis, however, the impact of GCs on the processes that regulate lipid accumulation has not been explored. Intracellular levels of active GC are dependent upon the activity of 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) and we have hypothesized that 11β-HSD1 activity can regulate lipid homeostasis in human adipose tissue (Chub-S7 cell line and primary cultures of human subcutaneous (sc) and omental (om) adipocytes. Across adipocyte differentiation, lipogenesis increased whilst β-oxidation decreased. GC treatment decreased lipogenesis but did not alter rates of β-oxidation in Chub-S7 cells, whilst insulin increased lipogenesis in all adipocyte cell models. Low dose Dexamethasone pre-treatment (5 nM) of Chub-S7 cells augmented the ability of insulin to stimulate lipogenesis and there was no evidence of adipose tissue insulin resistance in primary sc cells. Both cortisol and cortisone decreased lipogenesis; selective 11β-HSD1 inhibition completely abolished cortisone-mediated repression of lipogenesis. GCs have potent actions upon lipid homeostasis and these effects are dependent upon interactions with insulin. These in vitro data suggest that manipulation of GC availability through selective 11β-HSD1 inhibition modifies lipid homeostasis in human adipocytes

Hexose-6-phosphate Dehydrogenase Modulates 11β-Hydroxysteroid Dehydrogenase Type 1-Dependent Metabolism of 7-keto- and 7β-hydroxy-neurosteroids

BACKGROUND: The role of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) in the regulation of energy metabolism and immune system by locally reactivating glucocorticoids has been extensively studied. Experiments determining initial rates of enzyme activity revealed that 11beta-HSD1 can catalyze both the reductase and the dehydrogenase reaction in cell lysates, whereas it predominantly catalyzes the reduction of cortisone to cortisol in intact cells that also express hexose-6-phosphate dehydrogenase (H6PDH), which provides cofactor NADPH. Besides its role in glucocorticoid metabolism, there is evidence that 11beta-HSD1 is involved in the metabolism of 7-keto- and 7-hydroxy-steroids; however the impact of H6PDH on this alternative function of 11beta-HSD1 has not been assessed. METHODOLOGY: We investigated the 11beta-HSD1-dependent metabolism of the neurosteroids 7-keto-, 7alpha-hydroxy- and 7beta-hydroxy-dehydroepiandrosterone (DHEA) and 7-keto- and 7beta-hydroxy-pregnenolone, respectively, in the absence or presence of H6PDH in intact cells. 3D-structural modeling was applied to study the binding of ligands in 11beta-HSD1. PRINCIPAL FINDINGS: We demonstrated that 11beta-HSD1 functions in a reversible way and efficiently catalyzed the interconversion of these 7-keto- and 7-hydroxy-neurosteroids in intact cells. In the presence of H6PDH, 11beta-HSD1 predominantly converted 7-keto-DHEA and 7-ketopregnenolone into their corresponding 7beta-hydroxy metabolites, indicating a role for H6PDH and 11beta-HSD1 in the local generation of 7beta-hydroxy-neurosteroids. 3D-structural modeling offered an explanation for the preferred formation of 7beta-hydroxy-neurosteroids. CONCLUSIONS: Our results from experiments determining the steady state concentrations of glucocorticoids or 7-oxygenated neurosteroids suggested that the equilibrium between cortisone and cortisol and between 7-keto- and 7-hydroxy-neurosteroids is regulated by 11beta-HSD1 and greatly depends on the coexpression with H6PDH. Thus, the impact of H6PDH on 11beta-HSD1 activity has to be considered for understanding both glucocorticoid and neurosteroid action in different tissues

Advantage of rare infanticide strategies in an invasion experiment of behavioural polymorphism

Killing conspecific infants (infanticide) is among the most puzzling phenomena in nature. Stable polymorphism in such behaviour could be maintained by negative frequency-dependent selection (benefit of rare types). However, it is currently unknown whether there is genetic polymorphism in infanticidal behaviour or whether infanticide may have any fitness advantages when rare. Here we show genetic polymorphism in non-parental infanticide. Our novel invasion experiment confirms negative frequency-dependent selection in wild bank vole populations, where resource benefits allow an infanticidal strategy to invade a population of non-infanticidal individuals. The results show that infanticidal behaviour is highly heritable with genetic correlation across the sexes. Thus, a positive correlative response in male behaviour is expected when selection operates on females only and vice versa. Our results, on one hand, demonstrate potential benefits of infanticide, and on the other, they open a new perspective of correlative evolution of infanticide in females and males

Genetic polymorphism and structure of grey wolf (Canis lupus) populations in Eurasia

While the grey wolf would be a top predator in most of Eurasia's terrestrial ecosystems , hunting and environmental transformations have contributed to a strong reduction or eradication of populations over much of this area. Today's protection strategies depend on knowledge of population genetic variability and structure, and our analysis of those characteristics presented here draws on a unique sample set that can offer a comprehensive view of this. Indeed, as far as we know, this is the rst nuclear-based genetic study of wolf populations to encompass the Eurasian continent

Recycling between cortisol and cortisone in human splanchnic, subcutaneous adipose, and skeletal muscle tissues in vivo

11β-Hydroxysteroid dehydrogenase type 1 (11βHSD1) is a therapeutic target in metabolic syndrome because it catalyses reductase regeneration of cortisol from cortisone in adipose and liver. 11βHSD1 can also catalyze the reverse dehydrogenase reaction in vitro (e.g., if cofactor is limited). We used stable isotope tracers to test the hypothesis that both 11βHSD1-reductase and -dehydrogenase activities occur in human metabolic tissues in vivo. 1,2-[2H]2-Cortisone (d2-cortisone) was validated as a tracer for 11β-dehydrogenase activity and its inhibition by licorice. d2-Cortisone and 9,11,12,12-[2H]4-cortisol (d4-cortisol) (to measure 11β-reductase activity) were coinfused and venous samples obtained from skeletal muscle, subcutaneous adipose (n = 6), and liver (n = 4). Steroids were measured by liquid chromatography–tandem mass spectrometry and arteriovenous differences adjusted for blood flow. Data are means ± SEM. 11β-Reductase and -dehydrogenase activities were detected in muscle (cortisol release 19.7 ± 4.1 pmol/100 mL/min, d3-cortisol 5.9 ± 1.8 pmol/100 mL/min, and cortisone 15.2 ± 5.8 pmol/100 mL/min) and splanchnic (cortisol 64.0 ± 11.4 nmol/min, d3-cortisol 12.9 ± 2.1 nmol/min, and cortisone 19.5 ± 2.8 nmol/min) circulations. In adipose, dehydrogenase was more readily detected than reductase (cortisone release 38.7 ± 5.8 pmol/100 g/min). Active recycling between cortisol and cortisone in metabolic tissues in vivo may facilitate dynamic control of intracellular cortisol but makes consequences of dysregulation of 11βHSD1 transcription in obesity and diabetes unpredictable. Disappointing efficacy of 11βHSD1 inhibitors in phase II studies could be explained by lack of selectivity for 11β-reductase

TRPV1 in Brain Is Involved in Acetaminophen-Induced Antinociception

Background: Acetaminophen, the major active metabolite of acetanilide in man, has become one of the most popular overthe- counter analgesic and antipyretic agents, consumed by millions of people daily. However, its mechanism of action is still a matter of debate. We have previously shown that acetaminophen is further metabolized to N-(4-hydroxyphenyl)-5Z,8Z,11Z,14Z-eicosatetraenamide (AM404) by fatty acid amide hydrolase (FAAH) in the rat and mouse brain and that this metabolite is a potent activator of transient receptor potential vanilloid 1 (TRPV1) in vitro. Pharmacological activation of TRPV1 in the midbrain periaqueductal gray elicits antinociception in rats. It is therefore possible that activation of TRPV1 in the brain contributes to the analgesic effect of acetaminophen. Methodology/Principal Findings: Here we show that the antinociceptive effect of acetaminophen at an oral dose lacking hypolocomotor activity is absent in FAAH and TRPV1 knockout mice in the formalin, tail immersion and von Frey tests. This dose of acetaminophen did not affect the global brain contents of prostaglandin E-2 (PGE(2)) and endocannabinoids. Intracerebroventricular injection of AM404 produced a TRPV1-mediated antinociceptive effect in the mouse formalin test. Pharmacological inhibition of TRPV1 in the brain by intracerebroventricular capsazepine injection abolished the antinociceptive effect of oral acetaminophen in the same test. Conclusions: This study shows that TRPV1 in brain is involved in the antinociceptive action of acetaminophen and provides a strategy for developing central nervous system active oral analgesics based on the coexpression of FAAH and TRPV1 in the brain

Novel H6PDH mutations in two girls with premature adrenarche: 'apparent' and 'true' CRD can be differentiated by urinary steroid profiling.

Inactivating mutations in the enzyme hexose-6-phosphate dehydrogenase (H6PDH, encoded by H6PD) cause apparent cortisone reductase deficiency (ACRD). H6PDH generates cofactor NADPH for 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1, encoded by HSD11B1) oxo-reductase activity, converting cortisone to cortisol. Inactivating mutations in HSD11B1 cause true cortisone reductase deficiency (CRD). Both ACRD and CRD present with hypothalamic-pituitary-adrenal (HPA) axis activation and adrenal hyperandrogenism. To describe the clinical, biochemical and molecular characteristics of two additional female children with ACRD and to illustrate the diagnostic value of urinary steroid profiling in identifying and differentiating a total of six ACRD and four CRD cases. Clinical, biochemical and genetic assessment of two female patients presenting during childhood. In addition, results of urinary steroid profiling in a total of ten ACRD/CRD patients were compared to identify distinguishing characteristics. Case 1 was compound heterozygous for R109AfsX3 and a novel P146L missense mutation in H6PD. Case 2 was compound heterozygous for novel nonsense mutations Q325X and Y446X in H6PD. Mutant expression studies confirmed loss of H6PDH activity in both cases. Urinary steroid metabolite profiling by gas chromatography/mass spectrometry suggested ACRD in both cases. In addition, we were able to establish a steroid metabolite signature differentiating ACRD and CRD, providing a basis for genetic diagnosis and future individualised management. Steroid profile analysis of a 24-h urine collection provides a diagnostic method for discriminating between ACRD and CRD. This will provide a useful tool in stratifying unresolved adrenal hyperandrogenism in children with premature adrenarche and adult females with polycystic ovary syndrome (PCOS)

Multiple Organ System Defects and Transcriptional Dysregulation in the Nipbl+/− Mouse, a Model of Cornelia de Lange Syndrome

Cornelia de Lange Syndrome (CdLS) is a multi-organ system birth defects disorder linked, in at least half of cases, to heterozygous mutations in the NIPBL gene. In animals and fungi, orthologs of NIPBL regulate cohesin, a complex of proteins that is essential for chromosome cohesion and is also implicated in DNA repair and transcriptional regulation. Mice heterozygous for a gene-trap mutation in Nipbl were produced and exhibited defects characteristic of CdLS, including small size, craniofacial anomalies, microbrachycephaly, heart defects, hearing abnormalities, delayed bone maturation, reduced body fat, behavioral disturbances, and high mortality (75–80%) during the first weeks of life. These phenotypes arose despite a decrease in Nipbl transcript levels of only ∼30%, implying extreme sensitivity of development to small changes in Nipbl activity. Gene expression profiling demonstrated that Nipbl deficiency leads to modest but significant transcriptional dysregulation of many genes. Expression changes at the protocadherin beta (Pcdhb) locus, as well as at other loci, support the view that NIPBL influences long-range chromosomal regulatory interactions. In addition, evidence is presented that reduced expression of genes involved in adipogenic differentiation may underlie the low amounts of body fat observed both in Nipbl+/− mice and in individuals with CdLS