Liver upregulation of genes involved in cortisol production and action is associated with metabolic syndrome in morbidly obese patients

Fluorene-9-bisphenol exposure decreases locomotor activity and induces lipid-metabolism disorders by impairing fatty acid oxidation in zebrafish

AIMS

Fluorene-9-bisphenol (BHPF), as a substitute for bisphenol A, is used in many industries in daily life. Many studies have clarified its effects as an endocrine disruptor on organisms, but its effect on lipid metabolism of zebrafish larvae is not clear. Patients with non-alcoholic fatty liver disease (NAFLD) are more susceptible to external pollutants. It is not clear how BHPF perturbs lipid metabolism or promotes NAFLD progression.

MAIN METHODS

We explored the biological effects of BHPF on locomotor activity, inflammatory response, endoplasmic reticulum (ER) stress and lipid metabolism in zebrafish, especially in the mechanism of lipid homeostasis disorder. In addition, the role of BHPF in the progression of non-alcoholic fatty liver disease (NAFLD) was further explored.

KEY FINDINGS

We found that high concentration (100 nmol/L) BHPF caused retarded growth, mild lipid accumulation and reduced the locomotive activity of zebrafish larvae, accompanied by a decrease in endogenous cortisol level. At the same time, it caused the full activation of inflammation and ER stress. Rescue experiments by 25(OH)D₃ demonstrated that high concentration of BHPF caused defects in 1,25(OH)₂D₃ metabolic pathway through downregulation of cyp2r1, which further damaged pgc1a-mediated fatty acid oxidation and mitochondrial function, resulting in lipid accumulation. In summary, exposure to BHPF could damage lipid homeostasis and worsen the diet-induced NAFLD.

SIGNIFICANCE

Our findings provide new insights into the role of BHPF in development of overweight and obesity and also improve understanding of its toxicological mechanism. Our results play a warning role in the administration of environmental pollutants.

Regulation of 11β-HSD1 by GH/IGF-1 in key metabolic tissues may contribute to metabolic disease in GH deficient patients

Patients with growth hormone deficiency (GHD) have many clinical features in common with Cushing's syndrome (glucocorticoid excess) - notably visceral obesity, insulin resistance, muscle myopathy and increased vascular mortality. Within key metabolic tissues, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) converts cortisone to the active glucocorticoid, cortisol (11-dehydrocorticosterone and corticosterone in rodents respectively), and thus amplifies local glucocorticoid action. We hypothesize that 11β-HSD1 expression is negatively regulated by growth hormone (GH), and that GHD patients have elevated 11β-HSD1 within key metabolic tissues (leading to increased intracellular cortisol generation) which contributes to the clinical features of this disease. To identify the impact of GH excess/resistance on 11β-HSD1 in vivo, we measured mRNA expression in key metabolic tissues of giant mice expressing the bovine GH (bGH) gene, dwarf mice with a disrupted GH receptor (GHRKO) gene and mice expressing a gene encoding a GH receptor antagonist (GHA). Additionally, we assessed urine steroid markers of 11β-HSD1 activity in both GHRKO and bGH animals. 11β-HSD1 expression was decreased in gastrocnemius muscle (0.43-fold, p < 0.05), subcutaneous adipose (0.53-fold, p < 0.05) and epididymal adipose tissue (0.40-fold, p < 0.05), but not liver, in bGH mice compared to WT controls. This was paralleled by an increased percentage of 11-DHC (inactive glucocorticoid) present in the urine of bGH mice compared to WT controls (2.5-fold, p < 0.01) - consistent with decreased systemic 11β-HSD1 activity. By contrast, expression of 11β-HSD1 was increased in the liver of GHRKO (2.7-fold, p < 0.05) and GHA mice (2.0-fold, p < 0.05) compared to WT controls, but not gastrocnemius muscle, subcutaneous adipose tissue or epididymal adipose tissue. In summary, we have demonstrated a negative relationship between GH action and 11β-HSD1 expression which appears to be tissue specific. These data provide evidence that increased intracellular cortisol production within key tissues may contribute to metabolic disease in GHD patients.

Lack of adipose-specific hexose-6-phosphate dehydrogenase causes inactivation of adipose glucocorticoids and improves metabolic phenotype in mice

Excessive glucocorticoid (GC) production in adipose tissue promotes the development of visceral obesity and metabolic syndrome (MS). 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is critical for controlling intracellular GC production, and this process is tightly regulated by hexose-6-phosphate dehydrogenase (H6PDH). To better understand the integrated molecular physiological effects of adipose H6PDH, we created a tissue-specific knockout of the H6PDH gene mouse model in adipocytes (adipocyte-specific conditional knockout of H6PDH (H6PDHAcKO) mice). H6PDHAcKO mice exhibited almost complete absence of H6PDH expression and decreased intra-adipose corticosterone production with a reduction in 11β-HSD1 activity in adipose tissue. These mice also had decreased abdominal fat mass, which was paralleled by decreased adipose lipogenic acetyl-CoA carboxylase (ACC) and ATP-citrate lyase (ACL) gene expression and reduction in their transcription factor C/EBPα mRNA levels. Moreover, H6PDHAcKO mice also had reduced fasting blood glucose levels, increased glucose tolerance, and increased insulin sensitivity. In addition, plasma free fatty acid (FFA) levels were decreased with a concomitant decrease in the expression of lipase adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) in adipose tissue. These results indicate that inactivation of adipocyte H6PDH expression is sufficient to cause intra-adipose GC inactivation that leads to a favorable pattern of metabolic phenotypes. These data suggest that H6PDHAcKO mice may provide a good model for studying the potential contributions of fat-specific H6PDH inhibition to improve the metabolic phenotype in vivo. Our study suggests that suppression or inactivation of H6PDH expression in adipocytes could be an effective intervention for treating obesity and diabetes.

Tumor-Associated Neutrophils and Macrophages Promote Gender Disparity in Hepatocellular Carcinoma in Zebrafish

Hepatocellular carcinoma (HCC) occurs more frequently and aggressively in men than women, but the mechanistic basis of this gender disparity is obscure. Chronic inflammation is a major etiologic factor in HCC, so we investigated the role of cortisol in gender discrepancy in a zebrafish model of HCC. Inducible expression of oncogenic Kras^V12 in hepatocytes of transgenic zebrafish resulted in accelerated liver tumor progression in males. These tumors were more heavily infiltrated with tumor-associated neutrophils (TAN) and tumor-associated macrophages (TAM) versus females, and they both showed protumor gene expression and promoted tumor progression. Interestingly, the adrenal hormone cortisol was predominantly produced in males to induce Tgfb1 expression, which functioned as an attractant for TAN and TAM. Inhibition of cortisol signaling in males, or increase of cortisol level in females, decreased or increased the numbers of TAN and TAM, respectively, accompanied by corresponding changes in protumor molecular expression. Higher levels of cortisol, TGFB1, and TAN/TAM infiltration in males were also confirmed in human pre-HCC and HCC samples, features that positively correlated in human patients. These results identify increased cortisol production and TAN/TAM infiltration as primary factors in the gender disparity of HCC development in both fish and human. Cancer Res; 77(6); 1395-407. ©2017 AACR.

Low Body Mass Index in Endometriosis Is Promoted by Hepatic Metabolic Gene Dysregulation in Mice

The gynecological disease endometriosis is characterized by the deposition and proliferation of endometrial cells outside the uterus and clinically is linked to low body mass index (BMI). Gene expression in the liver of these women has not been reported. We hypothesized that endometriosis may impact hepatic gene expression, promoting a low BMI. To determine the effect of endometriosis on liver gene expression, we induced endometriosis in female mice by suturing donor mouse endometrium into the peritoneal cavity and measuring the weight of these mice. Dual-energy X-ray absorptiometry (DEXA) scanning of these mice showed lower body weight and lower total body fat than controls. Microarray analysis identified 26 genes differentially regulated in the livers of mice with endometriosis. Six of 26 genes were involved in metabolism. Four of six genes were upregulated and were related to weight loss, whereas two genes were downregulated and linked to obesity. Expression levels of Cyp2r1, Fabp4, Mrc1, and Rock2 were increased, whereas Igfbp1 and Mmd2 expression levels were decreased. Lep and Pparg, key metabolic genes in the pathways of the six genes identified from the microarray, were also upregulated. This dysregulation was specific to metabolic pathways. Here we demonstrate that endometriosis causes reduced body weight and body fat and disrupts expression of liver genes. We suggest that altered metabolism mediated by the liver contributes to the clinically observed low BMI that is characteristic of women with endometriosis. These findings reveal the systemic and multiorgan nature of endometriosis.

The role and regulation of 11β-hydroxysteroid dehydrogenase type 1 in obesity and the metabolic syndrome

The cortisol regenerating enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) amplifies tissue glucocorticoid levels, particularly in the liver and adipose tissue. The importance of this enzyme in causing metabolic disease was highlighted by transgenic mice which over- or under-expressed 11β-HSD1; consequently, selective 11β-HSD1 inhibitors have been widely developed as novel agents to treat obesity and type 2 diabetes mellitus (T2DM). This review focuses on the importance of 11β-HSD1 in humans which has been more difficult to ascertain. The recent development of a deuterated cortisol tracer has allowed us to quantify in vivo cortisol production by 11β-HSD1. These results have been surprising, as cortisol production rates by 11β-HSD1 are at least equivalent to that of the adrenal glands. The vast majority of this production is by the liver (>90%) with a smaller contribution from subcutaneous adipose tissue and possibly skeletal muscle, but with no detectable production from visceral adipose tissue. This tracer has also allowed us to quantify the tissue-specific regulation of 11β-HSD1 observed in obesity and obesity-associated T2DM, determine the likely basis for this dysregulation, and identify obese patients with T2DM as the group most likely to benefit from selective inhibition of 11β-HSD1. Some of these inhibitors have now reached Phase II clinical development, demonstrating efficacy in the treatment of T2DM. We review these results and discuss whether selective 11β-HSD1 inhibitors are likely to be an important new therapy for metabolic disease.

Glucocorticoid Excess Increases Hepatic 11β-HSD-1 Activity in Humans: Implications in Steroid-Induced Diabetes

CONTEXT

Animal studies indicate that glucocorticoids increase hepatic 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1) expression and activity.

OBJECTIVE

Our goal was to determine whether glucocorticoid excess increases cortisol production in the liver via 11β-HSD-1 enzyme pathway in humans.

DESIGN

A total of 1 mg each [4-(13)C] cortisone and [9,12,12-(2)H3] cortisol were ingested, and [1,2,6,7-(3)H] cortisol was infused to measure C13 cortisol (derived from ingested [4-(13)C] cortisone) turnover using the triple tracer technique, whereas glucose turnover was measured using isotope dilution technique following [6-6(2)H2] glucose infusion during a saline clamp.

SETTING

This study took place at the Mayo Clinic Clinical Research Unit.

PARTICIPANTS

Thirty nondiabetic healthy subjects participated.

INTERVENTION

Subjects were randomized to hydrocortisone (n = 15) or placebo 50 mg twice daily (n = 15) for 1 week.

OUTCOME MEASURES

Hepatic cortisol production and endogenous glucose production were measured.

RESULTS

Plasma cortisol concentrations were higher throughout the study period in hydrocortisone group. Rates of appearance of C13 cortisol and hepatic C13 cortisol production were higher in hydrocortisone vs placebo group, indicating increased hepatic 11β-HSD-1 activity. Higher plasma cortisol and presumably higher intrahepatic cortisol was associated with impaired suppression of endogenous glucose production in hydrocortisone vs placebo group.

CONCLUSION

Chronic glucocorticoid excess increases intrahepatic cortisone to cortisol conversion via the 11β-HSD-1 pathway. The extent to which this causes or exacerbates steroid induced hepatic insulin resistance remains to be determined.

Hepatic and visceral adipose tissue 11βHSD1 expressions are markers of body weight loss after bariatric surgery

OBJECTIVE

Cortisolemia and 11βHSD1 in liver and adipose tissue are altered in obesity. However, their participation in the development of obesity remains unclear. This study analyzed these parameters in the transition from morbid to type 1 obesity after bariatric surgery.

METHODS

A group of 34 patients with morbid obesity and 22 nonobese subjects were recruited. Initial hypothalamus-pituitary-adrenal (HPA) basal activity and 11βHSD1 mRNA expression in liver, subcutaneous (SAT), and visceral adipose tissue (VAT) were evaluated. A year after bariatric surgery (weight loss of 48 kg), these parameters were reappraised in plasma, SAT, and liver.

RESULTS

Body weight loss was accompanied by a downshift in basal HPA activity and 11βHSD1 expression in SAT. In patients with morbid obesity, 11βHSD1 expression correlated positively with BMI in VAT and negatively in liver at 6 and 12 months after surgery. In SAT, a correlation was observed with body weight only when patients showed type 1 obesity. Insulin, glucose, and HOMA correlated positively with all the HPA indicators and 11βHSD1 expression in SAT.

CONCLUSIONS

Body weight loss after bariatric surgery is accompanied by a downshift in basal HPA activity. Hepatic and VAT 11βHSD1 expressions in morbid obesity are predictors of body weight loss.

Flavin-containing monooxygenase 3 as a potential player in diabetes-associated atherosclerosis

Despite the well-documented association between insulin resistance and cardiovascular disease, the key targets of insulin relevant to the development of cardiovascular disease are not known. Here, using non-biased profiling methods, we identify the enzyme flavin-containing monooxygenase 3 (Fmo3) to be a target of insulin. FMO3 produces trimethylamine N-oxide (TMAO), which has recently been suggested to promote atherosclerosis in mice and humans. We show that FMO3 is suppressed by insulin in vitro, increased in obese/insulin resistant male mice and increased in obese/insulin-resistant humans. Knockdown of FMO3 in insulin-resistant mice suppresses FoxO1, a central node for metabolic control, and entirely prevents the development of hyperglycaemia, hyperlipidemia and atherosclerosis. Taken together, these data indicate that FMO3 is required for FoxO1 expression and the development of metabolic dysfunction.

Maternal restraint stress during pregnancy in mice induces 11β-HSD1-associated metabolic changes in the livers of the offspring

In rats, maternal exposure to restraint stress during pregnancy can induce abnormalities in the cardiovascular and central nervous systems of the offspring. These effects are mediated by long-lasting hyperactivation of the hypothalamic–pituitary–adrenal axis. However, little is known about the potential effects of stress during pregnancy on metabolic systems. We examined the effect of restraint stress in pregnant mice on the liver function of their offspring. The offspring of stressed mothers showed significantly higher lipid accumulation in the liver after weaning than did the controls; this accumulation was associated with increased expression of lipid metabolism-related proteins such as alanine aminotransferase 2 diglyceride acyltransferase 1, peroxisome proliferator-activated receptor gamma and glucocorticoid receptor. Additionally, we observed increased levels of 11β-hydroxysteroid dehydrogenase type 1, an intercellular mediator that converts glucocorticoid from the inactive to the active form, in the foetal and postnatal periods. These results indicate that restraint stress in pregnancy in mice induces metabolic abnormalities via 11β-hydroxysteroid dehydrogenase type 1-related pathways in the foetal liver. It is therefore possible that exposure to stress in pregnant women may be a risk factor for metabolic syndromes (e.g. fatty liver) in children.

Cortisol in tissue and systemic level as a contributing factor to the development of metabolic syndrome in severely obese patients

CONTEXT

Adrenal and extra-adrenal cortisol production may be involved in the development of metabolic syndrome (MetS).

OBJECTIVE

To investigate the activity of the hypothalamic-pituitary-adrenal (HPA) axis and the expression of HSD11B1, nuclear receptor subfamily 3, group C, member 1 (glucocorticoid receptors) α (NR3C1α) and β (NR3C1β) in the liver, subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) of severely obese patients with and without MetS.

METHODS

The study included 37 severely obese patients (BMI ≥ 40 kg/m(2)), 19 with MetS (MetS+ group) and 18 without (MetS- group), studied before and during bariatric surgery. Before the day of surgery, urinary free cortisol (UFC) and diurnal variation of serum and salivary cortisol were estimated. During surgery, biopsies of the liver, VAT and SAT were obtained. The expression of HSD11B1, NR3C1α and NR3C1β was evaluated by RT-PCR.

RESULTS

UFC and area under the curve for 24-h profiles of serum and salivary cortisol were lower in the MetS- group. In the MetS- group, mRNA levels of HSD11B1 in liver exhibited a negative correlation with liver NR3C1α (LNR3C1α) and VAT expression of HSD11B1 was lower than the MetS+ group.

CONCLUSIONS

We observed a downregulation of the NR3C1α expression and lower VAT mRNA levels of HSD11B1 in the MetS- group, indicating a lower selective tissue cortisol production and action that could protect these patients from the metabolic consequences of obesity. In the MetS- group, a lower activity of the HPA axis was also detected. Taken together, cortisol in tissue and systematic level might play a role in the development of MetS in severely obese patients.

Developmental regulation of key gluconeogenic molecules in nonhuman primates

Aberrant glucose regulation is common in preterm and full‐term neonates leading to short and long‐term morbidity/mortality; however, glucose metabolism in this population is understudied. The aim of this study was to investigate developmental differences in hepatic gluconeogenic pathways in fetal/newborn baboons. Fifteen fetal baboons were delivered at 125 day (d) gestational age (GA), 140d GA, and 175d GA (term = 185d GA) via cesarean section and sacrificed at birth. Term and healthy adult baboons were used as controls. Protein content and gene expression of key hepatic gluconeogenic molecules were measured: cytosolic and mitochondrial phosphoenolpyruvate carboxykinase (PEPCK‐C and PEPCK‐M), glucose‐6‐phosphatase‐alpha (G6Pase‐α), G6Pase‐β, fructose‐1,6‐bisphosphatase (FBPase), and forkhead box‐O1 (FOXO1). Protein content of PEPCK‐M increased with advancing gestation in fetal baboons (9.6 fold increase from 125d GA to 175d GA, P < 0.001). PEPCK‐C gene expression was consistent with these developmental differences. Phosphorylation of FOXO1 was significantly lower in preterm fetal baboons compared to adults, and gene expression of FOXO1 was lower in all neonates when compared to adults (10% and 62% of adults respectively, P < 0.05). The FOXO1 target gene G6Pase expression was higher in preterm animals compared to term animals. No significant differences were found in G6Pase‐α, G6Pase‐β, FOXO1, and FBPase during fetal development. In conclusion, significant developmental differences are found in hepatic gluconeogenic molecules in fetal and neonatal baboons, which may impact the responses to insulin during the neonatal period. Further studies under insulin‐stimulated conditions are required to understand the physiologic impact of these maturational differences.

Significant developmental differences were found in several hepatic gluconeogenic molecules. In particular, phosphorylated FOXO1 was significantly reduced in the liver of premature fetal baboons compared to adults and may contribute the increased incidence of hyperglycemia seen in prematurity. In addition, PEPCK increased with advancing gestational age and may play a key role in glucose regulation during the newborn period.

Glucocorticoids regulate the metabolic hormone FGF21 in a feed-forward loop

Hormones such as fibroblast growth factor 21 (FGF21) and glucocorticoids (GCs) play crucial roles in coordinating the adaptive starvation response. Here we examine the interplay between these hormones. It was previously shown that FGF21 induces corticosterone levels in mice by acting on the brain. We now show that this induces the expression of genes required for GC synthesis in the adrenal gland. FGF21 also increases corticosterone secretion from the adrenal in response to ACTH. We further show that the relationship between FGF21 and GCs is bidirectional. GCs induce Fgf21 expression in the liver by acting on the GC receptor (GR). The GR binds in a ligand-dependent manner to a noncanonical GR response element located approximately 4.4 kb upstream of the Fgf21 transcription start site. The GR cooperates with the nuclear fatty acid receptor, peroxisome proliferator-activated receptor-α, to stimulate Fgf21 transcription. GR and peroxisome proliferator-activated receptor-α ligands have additive effects on Fgf21 expression both in vivo and in primary cultures of mouse hepatocytes. We conclude that FGF21 and GCs regulate each other's production in a feed-forward loop and suggest that this provides a mechanism for bypassing negative feedback on the hypothalamic-pituitary-adrenal axis to allow sustained gluconeogenesis during starvation.

Harmful effects of functional hypercortisolism: a working hypothesis

Functional hypercortisolism (FH) is caused by conditions able to chronically activate hypothalamic-pituitary-adrenal axis and usually occurs in cases of major depression, anorexia nervosa, bulimia nervosa, alcoholism, diabetes mellitus, simple obesity, polycystic ovary syndrome, obstructive sleep apnea syndrome, panic disorder, generalized anxiety disorder, shift work, and end-stage renal disease. Most of these states belong to pseudo-Cushing disease, a condition which is difficult to distinguish from Cushing's syndrome and characterized not only by biochemical findings but also by objective ones that can be attributed to hypercortisolism (e.g., striae rubrae, central obesity, skin atrophy, easy bruising, etc.). This hormonal imbalance, although reversible and generally mild, could mediate some systemic complications, mainly but not only of a metabolic/cardiovascular nature, which are present in these states and are largely the same as those present in Cushing's syndrome. In this review we aim to discuss the evidence suggesting the emerging negative role for FH.

Tissue-specific dysregulation of cortisol regeneration by 11βHSD1 in obesity: has it promised too much?

Cushing's syndrome, caused by increased production of cortisol, leads to metabolic dysfunction including visceral adiposity, hypertension, hyperlipidaemia and type 2 diabetes. The similarities with the metabolic syndrome are striking and major efforts have been made to find obesity-associated changes in the regulation of glucocorticoid action and synthesis, both at a systemic level and tissue level. Obesity is associated with tissue-specific alterations in glucocorticoid metabolism, with increased activity of the glucocorticoid-regenerating enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) in subcutaneous adipose tissue and decreased conversion of cortisone to cortisol, interpreted as decreased 11βHSD1 activity, in the liver. In addition, genetic manipulation of 11βHSD1 activity in rodents can either induce (by overexpression of Hsd11b1, the gene encoding 11βHSD1) or prevent (by knocking out Hsd11b1) obesity and metabolic dysfunction. Taken together with earlier evidence that non-selective inhibitors of 11βHSD1 enhance insulin sensitivity, these results led to the hypothesis that inhibition of 11βHSD1 might be a promising target for treatment of the metabolic syndrome. Several selective 11βHSD1 inhibitors have now been developed and shown to improve metabolic dysfunction in patients with type 2 diabetes, but the small magnitude of the glucose-lowering effect has precluded their further commercial development.This review focuses on the role of 11βHSD1 as a tissue-specific regulator of cortisol exposure in obesity and type 2 diabetes in humans. We consider the potential of inhibition of 11βHSD1 as a therapeutic strategy that might address multiple complications in patients with type 2 diabetes, and provide our thoughts on future directions in this field.

A calcium-deficient diet in rat dams during gestation and nursing affects hepatic 11β-hydroxysteroid dehydrogenase-1 expression in the offspring

BACKGROUND

Prenatal malnutrition can affect the phenotype of offspring by changing epigenetic regulation of specific genes. Several lines of evidence demonstrate that calcium (Ca) plays an important role in the pathogenesis of insulin resistance syndrome. We hypothesized that pregnant female rats fed a Ca-deficient diet would have offspring with altered hepatic glucocorticoid-related gene expression and that lactation would modify these alterations.

METHODOLOGY

We determined the effects of Ca deficiency during pregnancy and/or lactation on hepatic 11β-hydroxysteroid dehydrogenase-1 (Hsd11b1) expression in offspring. Female Wistar rats consumed either a Ca-deficient (D: 0.008% Ca) or control (C: 0.90% Ca) diet ad libitum from 3 weeks preconception to 21 days postparturition. On postnatal day 1, pups were cross-fostered to the same or opposite dams and divided into the following four groups: CC, DD, CD, and DC (first letter: original mother's diet; second letter: nursing mother's diet). All offspring were fed a control diet beginning at weaning (day 21) and were killed on day 200 ± 7. Serum insulin and adipokines in offspring were measured using ELISA kits.

PRINCIPAL FINDINGS

In males, mean levels of insulin, glucose, and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) were higher in the DD and DC groups than in the CC group. We found no difference in HOMA-IR between the CC and CD groups in either males or females. Expression of Hsd11b1 was lower in male DD rats than in CC rats. Hsd11b1 expression in male offspring nursed by cross-fostered dams was higher than that in those nursed by dams fed the same diet; CC vs. CD and DD vs. DC. In females, Hsd11b1 expression in DC rats was higher than that in CC rats.

CONCLUSIONS

These findings indicated that maternal Ca restriction during pregnancy and/or lactation alters postnatal growth, Hsd11b1 expression, and insulin resistance in a sex-specific manner.

11β-Hydroxysteroid dehydrogenase 1: translational and therapeutic aspects

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) interconverts the inactive glucocorticoid cortisone and its active form cortisol. It is widely expressed and, although bidirectional, in vivo it functions predominantly as an oxoreductase, generating active glucocorticoid. This allows glucocorticoid receptor activation to be regulated at a prereceptor level in a tissue-specific manner. In this review, we will discuss the enzymology and molecular biology of 11β-HSD1 and the molecular basis of cortisone reductase deficiencies. We will also address how altered 11β-HSD1 activity has been implicated in a number of disease states, and we will explore its role in the physiology and pathologies of different tissues. Finally, we will address the current status of selective 11β-HSD1 inhibitors that are in development and being tested in phase II trials for patients with the metabolic syndrome. Although the data are preliminary, therapeutic inhibition of 11β-HSD1 is also an exciting prospect for the treatment of a variety of other disorders such as osteoporosis, glaucoma, intracranial hypertension, and cognitive decline.

Specific reduction of G6PT may contribute to downregulation of hepatic 11β-HSD1 in diabetic mice

Pre-receptor activation of glucocorticoids via 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1 (HSD11B1)) has been identified as an important mediator of the metabolic syndrome. Hexose-6-phosphate dehydrogenase (H6PDH) mediates 11β-HSD1 amplifying tissue glucocorticoid production by driving intracellular NADPH exposure to 11β-HSD1 and requires glucose-6-phosphate transporter (G6PT (SLC37A4)) to maintain its activity. However, the potential effects of G6PT on tissue glucocorticoid production in type 2 diabetes and obesity have not yet been defined. Here, we evaluated the possible role of G6PT antisense oligonucleotides (G6PT ASO) in the pre-receptor metabolism of glucocorticoids as related to glucose homeostasis and insulin tolerance by examining the production of 11β-HSD1 and H6PDH in both male db/+ and db/db mouse liver tissue. We observed that G6PT ASO treatment of db/db mice markedly reduced hepatic G6PT mRNA and protein levels and substantially diminished the activation of hepatic 11β-HSD1 and H6PDH. Reduction of G6pt expression was correlated with the suppression of both hepatic gluconeogenic enzymes G6Pase and PEPCK and corresponded to the improvement of hyperglycemia and insulin resistance in db/db mice. Addition of G6PT ASO to mouse hepa1-6 cells led to a dose-dependent decrease in 11B-Hsd1 production. Knockdown of G6PT with RNA interference also impaired 11B-Hsd1 expression and showed comparable effects to H6pdh siRNA on silencing of H6pdh and 11B-Hsd1 expression in these intact cells. These findings suggest that G6PT plays an important role in the modulation of pre-receptor activation of glucocorticoids and provides new insights into the role of G6PT in the development of type 2 diabetes.

Effects of 11β-hydroxysteroid dehydrogenase-1 inhibition on hepatic glycogenolysis and gluconeogenesis

The aim of this study was to determine the effect of prolonged 11β-hydroxysteroid dehydrogenase-1 (11β-HSD1) inhibition on basal and hormone-stimulated glucose metabolism in fasted conscious dogs. For 7 days prior to study, either an 11β-HSD1 inhibitor (HSD1-I; n = 6) or placebo (PBO; n = 6) was administered. After the basal period, a 4-h metabolic challenge followed, where glucagon (3×-basal), epinephrine (5×-basal), and insulin (2×-basal) concentrations were increased. Hepatic glucose fluxes did not differ between groups during the basal period. In response to the metabolic challenge, hepatic glucose production was stimulated in PBO, resulting in hyperglycemia such that exogenous glucose was required in HSD-I (P < 0.05) to match the glycemia between groups. Net hepatic glucose output and endogenous glucose production were decreased by 11β-HSD1 inhibition (P < 0.05) due to a reduction in net hepatic glycogenolysis (P < 0.05), with no effect on gluconeogenic flux compared with PBO. In addition, glucose utilization (P < 0.05) and the suppression of lipolysis were increased (P < 0.05) in HSD-I compared with PBO. These data suggest that inhibition of 11β-HSD1 may be of therapeutic value in the treatment of diseases characterized by insulin resistance and excessive hepatic glucose production.