Metformin and Bone Metabolism in Endogenous Glucocorticoid Excess: An Exploratory Study.

Context: Glucocorticoid excess exhibits multiple detrimental effects by its catabolic properties. Metformin was recently suggested to protect from adverse metabolic side-effects of glucocorticoid treatment. Whether metformin is beneficial in patients with endogenous glucocorticoid excess has not been clarified. Objective: To evaluate the phenotype in patients with endogenous Cushing's syndrome (CS) treated with metformin at the time of diagnosis. Patients and Methods: As part of the German Cushing's Registry we selected from our prospective cohort of 96 patients all 10 patients who had been on pre-existing metformin treatment at time of diagnosis (CS-MET). These 10 patients were matched for age, sex and BMI with 16 patients without metformin treatment (CS-NOMET). All patients had florid CS at time of diagnosis. We analyzed body composition, metabolic parameters, bone mineral density and bone remodeling markers, muscle function and quality of life. Results: As expected, diabetes was more prevalent in the CS-MET group, and HbA1c was higher. In terms of comorbidities and the degree of hypercortisolism, the two groups were comparable. We did not observe differences in terms of muscle function or body composition. In contrast, bone mineral density in metformin-treated patients was superior to the CS-NOMET group at time of diagnosis (median T-Score -0.8 versus -1.4, p = 0.030). CS-MET patients showed decreased ß-CTX levels at baseline (p = 0.041), suggesting reduced bone resorption under metformin treatment during glucocorticoid excess. Conclusion: This retrospective cohort study supports potential protective effects of metformin in patients with endogenous glucocorticoid excess, in particular on bone metabolism.

Identification of dicyclohexyl phthalate as a glucocorticoid receptor antagonist by molecular docking and multiple in vitro methods.

The potential activities of phthalate esters (PAEs) that interfere with the endocrine system have been focused recently. However, information on modulating the glucocorticoid receptor (GR) of PAEs is scarce. Our aim was to evaluate the agonistic / antagonistic properties of PAEs on human GR. Luciferase reporter gene assay revealed that the tested chemicals displayed no agonistic effects but dicyclohexyl phthalate (DCHP) exerted antagonistic activity in a dose-responsive manner for GR in HeLa cells. The effects of DCHP on dexamethasone (DEX)-induced GR nuclear translocation and gene expression of glucocorticoid-responsive gene expression (G6Pase, PEPCK, FAS, GILZ and MKP-1), as well as protein expression of G6Pase and PEPCK were further examined by RT-qPCR and western blot analysis. DCHP antagonized DEX-induced GR nuclear translocation and suppressed gene expression in both mRNA and protein levels. Furthermore, the results of molecular docking and molecular dynamics simulation showed that DCHP could bind to GR and exhibited potential regulation on this target protein. Collectively, we demonstrate that DCHP may act as a GR antagonist in vitro and is considered to exert endocrine effects via human GR.

Glucocorticoids attenuate interleukin-6-induced c-Fos and Egr1 expression and impair neuritogenesis in PC12 cells.

Interleukin-6 (IL-6) is a cytokine primarily known for immune regulation. There is also growing evidence that IL-6 triggers neurogenesis and impacts neural development, both life-long occurring processes that can be impaired by early-life and adult stress. Stress induces the release of glucocorticoids by activation of the hypothalamic-pituitary-adrenal (HPA) axis. On the cellular level, glucocorticoids act via the ubiquitously expressed glucocorticoid receptor. Thus, we aimed to elucidate whether glucocorticoids affect IL-6-induced neural development. Here, we show that IL-6 signalling induces neurite outgrowth in adrenal pheochromocytoma PC12 cells in a mitogen-activated protein kinase (MAPK) pathway-dependent manner, since neurite outgrowth was diminished upon Mek-inhibitor treatment. Using quantitative biochemical approaches, such as qRT-PCR analysis of Hyper-IL-6 treated PC12 cells, we show that neurite outgrowth induced by IL-6 signalling is accompanied by early and transient MAPK-dependent mRNA expression of immediate early genes coding for proteins such as early growth response protein 1 (Egr1) and c-Fos. This correlates with reduced proliferation and prolonged G0/G1 cell cycle arrest as determined by monitoring the cellular DNA content using flow cytometry. These results indicate for IL-6 signalling-induced neural differentiation. Interestingly, the glucocorticoid Dexamethasone impairs early IL-6 signalling-induced mRNA expression of c-Fos and Egr1 and restrains neurite outgrowth. Impaired Egr1 and c-Fos expression in neural development is implicated in the aetiology of neuropathologies. Thus, it appears likely that stress-induced release of glucocorticoids, as well as therapeutically administered glucocorticoids, contribute to the development of neuropathologies by reducing the expression of Egr1 and c-Fos, and by restraining IL-6-dependent neural differentiation.

Clinical stage molecule PT150 is a modulator of glucocorticoid and androgen receptors with antiviral activity against SARS-CoV-2.

PT150 is a clinical-stage molecule, taken orally, with a strong safety profile having completed Phase 1 and Phase 2 clinical trials for its original use as an antidepressant. It has an active IND for COVID-19. Antiviral activities have been found for PT150 and other members of its class in a variety of virus families; thus, it was now tested against SARS-CoV-2 in human bronchial epithelial lining cells and showed effective 90% inhibitory antiviral concentration (EC90) of 5.55 µM. PT150 is a member of an extended platform of novel glucocorticoid receptor (GR) and androgen receptor (AR) modulating molecules. In vivo, their predominant net effect is one of systemic glucocorticoid antagonism, but they also show direct downregulation of AR and minor GR agonism at the cellular level. We hypothesize that anti-SARS-CoV-2 activity depends in part on this AR downregulation through diminished TMPRSS2 expression and modulation of ACE2 activity. Given that hypercortisolemia is now suggested to be a significant co-factor for COVID-19 progression, we also postulate an additive role for its potent immunomodulatory effects through systemic antagonism of cortisol.

Inmunosupresión en el trasplante hepático en la era covid-19 / Liver transplant immunosuppression during the covid-19 pandemic

La infección por el virus SARS-CoV-2 ha producido una pandemia con graves consecuencias sobre nuestro sistema sanitario. Aunque el colectivo de pacientes trasplantados hepáticos representa solo una minoría de la población, los hepatólogos que seguimos a estos pacientes hemos intentado coordinar esfuerzos para protocolizar el manejo de la inmunosupresión durante la infección por SARS-CoV-2. Aunque no hay estudios sólidos que avalen recomendaciones generales, las experiencias con otras infecciones víricas (hepatitis C, citomegalovirus) sugieren que el manejo de la inmunosupresión sin micofenolato mofetilo ni inhibidores m-Tor (fármacos que además se asocian a leucopenia y linfopenia) puede resultar beneficiosa. Es importante además prestar atención a las posibles interacciones farmacológicas, especialmente en el caso de tacrolimus, con algunos de los tratamientos con efecto antiviral que se administran en el contexto de la covid-19 (lopinavir/ritonavir, azitromicina). Finalmente, deberá tenerse en cuenta el efecto inmunosupresor de fármacos inmunomoduladores (tocilizumab y similares) que se administran en pacientes con enfermedad pulmonar severa. En el artículo se revisan los mecanismos de actuación de los diferentes fármacos inmunosupresores, su potencial efecto sobre la infección por SARS-CoV-2 y se sugieren unas pautas en el manejo de la inmunosupresión

SARS-CoV-2 infection has produced a pandemic with serious consequences for our health care system. Although liver transplant patients represent only a minority of the population, the hepatologists who follow these patients have tried to coordinate efforts to produce a protocol the management of immunosuppression during SARS-CoV-2 infection. Although there are no solid studies to support general recommendations, experiences with other viral infections (hepatitis C, cytomegalovirus) suggest that management of immunosuppression without mycophenolate mofetil or m-Tor inhibitors (drugs that are also associated with leukopenia and lymphopenia) may be beneficial. It is also important to pay attention to possible drug interactions, especially in the case of tacrolimus, with some of the treatments with antiviral effect given in the context of COVID 19 (lopinavir/ritonavir, azithromycin). Finally, the immunosuppressive effect of immunomodulating drugs (tocilizumab and similar) administered to patients with severe lung disease should be taken into account. The mechanisms of action of the different immunosuppressive drugs are reviewed in this article, as well as their potential effect on SARS-CoV-2 infection, and suggests guidelines for the management of immunosuppression

Prunella vulgaris L protects glucocorticoids-induced osteogenesis inhibition in bone marrow mesenchymal stem cells through activating the Smad pathway.

OBJECTIVE: To elucidate the role of Prunella vulgaris L (PVL) in protecting glucocorticoids (GC)-induced osteogenesis inhibition, thereafter, protecting the deterioration of osteoporosis (OP). MATERIALS AND METHODS: Cell Counting Kit-8 (CCK-8) assay was conducted to assess the influence of PVL treatment on MSCs viability. Osteogenesis in MSCs was induced by Dexamethasone (DEX) stimulation. Regulatory effects of PVL on osteogenesis-related gene expressions, ALP activity, and mineralization ability in DEX-induced MSCs were determined. At last, protein levels of p-Smad1/5/9 and total-Smad1/5/9 influenced by DEX and PVL were measured by Western blot. RESULTS: PVL treatment did not pose a time- or dose-dependent influence on MSCs viability. DEX induction in MSCs downregulated ALP, RUNX2, Bglap, and Osterix. ALP activity and mineralization in DEX-induced MSCs were suppressed. Downregulated osteogenesis-related genes decreased ALP activity and mineralization in MSCs undergoing DEX stimulation were partially reversed by PVL treatment. Moreover, the downregulated p-Smad1/5/9 level in DEX-induced MSCs was elevated by PVL treatment, while total-Smad1/5/9 was not affected. CONCLUSIONS: PVL alleviated GC-induced suppression in MSCs osteogenesis by activating the Smad pathway, thereafter, protecting the deterioration of OP.

Pharmacological suppression of endogenous glucocorticoid synthesis attenuated blood pressure and heart rate response to acute restraint in Wistar rats.

Glucocorticoids (GCS) are known to modulate cardiovascular response during stress conditions. The present study was aimed to test the hypothesis that permissive and/or stimulating effect of GCs is essential for the maintenance of peripheral vascular resistance and for the adequate response of cardiovascular system to stressor exposure. The effects of acute pharmacological adrenalectomy (PhADX) on humoral and cardiovascular parameters were studied in adult Wistar rats under the basal conditions and during the acute restraint stress. Acute PhADX was performed by the administration of metyrapone and aminoglutethimide (100 mg/kg s.c. of each drug) resulting in a suppression of endogenous glucocorticoid synthesis. Blood pressure (BP), heart rate (HR) and core body temperature were measured using radiotelemetry. BP responses to administration of vasoactive agents were determined in pentobarbital-anesthetized animals. PhADX considerably attenuated stress-induced increase of BP, HR and core body temperature. PhADX did not abolish BP and HR lowering effects of ganglionic blocker pentolinium indicating preserved sympathetic function in PhADX rats. BP response to exogenous norepinephrine administration was attenuated in PhADX rats, suggesting reduced sensitivity of cardiovascular system. Suppression of corticosterone synthesis by PhADX increased basal plasma levels of ACTH, aldosterone and plasma renin activity in unstressed animals but there was no further increase of these hormones following stressor exposure. In conclusion, PhADX attenuated stress-induced rise of blood pressure, heart rate and core body temperature indicating an important permissive and/or stimulating role of glucocorticoids in the maintenance of the adequate response of cardiovascular system and thermoregulation to several stimuli including acute exposure to stressor.

Bed nuclei of the stria terminalis modulate memory consolidation via glucocorticoid-dependent and -independent circuits.

There is extensive evidence that glucocorticoid hormones enhance memory consolidation, helping to ensure that emotionally significant events are well remembered. Prior findings suggest that the anteroventral region of bed nuclei of the stria terminalis (avBST) regulates glucocorticoid release, suggesting the potential for avBST activity to influence memory consolidation following an emotionally arousing learning event. To investigate this issue, male Sprague-Dawley rats underwent inhibitory avoidance training and repeated measurement of stress hormones, immediately followed by optogenetic manipulations of either the avBST or its projections to downstream regions, and 48 h later were tested for retention. The results indicate that avBST inhibition augmented posttraining pituitary-adrenal output and enhanced the memory for inhibitory avoidance training. Pretreatment with a glucocorticoid synthesis inhibitor blocked the memory enhancement as well as the potentiated corticosterone response, indicating the dependence of the memory enhancement on glucocorticoid release during the immediate posttraining period. In contrast, posttraining avBST stimulation decreased retention yet had no effect on stress hormonal output. Subsequent experiments revealed that inhibition of avBST input to the paraventricular hypothalamus enhanced stress hormonal output and subsequent retention, whereas stimulation did not affect either. Conversely, stimulation-but not inhibition-of avBST input to the ventrolateral periaqueductal gray impaired consolidation, whereas neither manipulation affected glucocorticoid secretion. These findings indicate that divergent pathways from the avBST are responsible for the mnemonic effects of avBST inhibition versus stimulation and do so via glucocorticoid-dependent and -independent mechanisms, respectively.

Effects of fluvoxamine on nerve growth factor-induced neurite outgrowth inhibition by dexamethasone in PC12 cells.

In the present study, we examined the effects of fluvoxamine on nerve growth factor (NGF)-induced neurite outgrowth inhibition by dexamethasone (DEX) in PC12 cells. Fluvoxamine increased NGF-induced neurite outgrowth. Compared with co-treatment with NGF and fluvoxamine, p-Akt levels were higher than the values without fluvoxamine. The phosphorylated extracellular regulated kinase 1/2 levels were slightly increased by co-treatment with NGF and fluvoxamine. Fluvoxamine concentration-dependently improved NGF-induced neurite outgrowth inhibition by DEX. Fluvoxamine also improved the decrease in the NGF-induced p-Akt level caused by DEX. Interestingly, the sigma-1 receptor antagonist NE-100 blocked the improvement effects of fluvoxamine on NGF-induced neurite outgrowth inhibition by DEX. The selective sigma-1 receptor agonist PRE-084 also improved NGF-induced neurite outgrowth inhibition by DEX, which is blocked by NE-100. These results indicate that the improvement effects of fluvoxamine on NGF-induced neurite outgrowth inhibition by DEX may be attributable to the phosphorylation of Akt and the sigma-1 receptor.

Investigating dopamine and glucocorticoid systems as underlying mechanisms of anhedonia.

RATIONALE: Anhedonia, a deficit in reward processing, is an endophenotype of several neuropsychiatric conditions. Despite its prevalence and debilitating effects, treatments for anhedonia are lacking, primarily because its underlying mechanisms are poorly understood. Dopamine (DA) has been implicated in anhedonia through its role in reward-related learning; glucocorticoid systems may also be involved in that anhedonia is often preceded by chronic stress. OBJECTIVE: This study investigated DA and glucocorticoid systems in anhedonia using a rat version of the probabilistic reward task (PRT). METHODS: Adult male Wistar rats were trained on the PRT and then tested following: (1) activation or inhibition of DA activity induced by amphetamine (AMPH) or pramipexole (PRAMI) injections, (2) chronic mild stress (CMS), or (3) glucocorticoid system activation (dexamethasone (DEX)) or inhibition (mifepristone (MIFE)). RESULTS: AMPH increased and PRAMI decreased response bias, pointing to enhanced and diminished reward responsiveness with DA agonism and antagonism, respectively. CMS reduced response bias but only in a subpopulation of rats. DEX also decreased response bias, suggesting that glucocorticoid processes contribute to anhedonia, although glucocorticoid inhibition (MIFE) had no effect. None of the manipulations altered the ability to detect and respond to reward-paired stimuli. CONCLUSIONS: These results confirm a role of DA in anhedonia and elucidate the contribution of the glucocorticoid system to this effect. In addition, chronic stress may interfere with normal DA functioning, leading to impaired reward-related learning in some animals. These findings may direct future treatment of anhedonia by targeting DA and glucocorticoid systems, as well as a possible interaction between the two.

Glucocorticoid receptor modulators.

The glucocorticoid hormone cortisol acts throughout the body to support circadian processes and adaptation to stress. The glucocorticoid receptor is the target of cortisol and of synthetic glucocorticoids, which are used widely in the clinic. Both agonism and antagonism of the glucocorticoid receptor may be beneficial in disease, but given the wide expression of the receptor and involvement in various processes, beneficial effects are often accompanied by unwanted side effects. Selective glucocorticoid receptor modulators are ligands that induce a receptor conformation that allows activation of only a subset of downstream signaling pathways. Such molecules thereby combine agonistic and antagonistic properties. Here we discuss the mechanisms underlying selective receptor modulation and their promise in treating diseases in several organ systems where cortisol signaling plays a role.

The glucocorticoid antagonist mifepristone attenuates sound-induced long-term deficits in auditory nerve response and central auditory processing in female rats.

Systemic corticosteroids have been the mainstay of treatment for various hearing disorders for more than 30 yr. Accordingly, numerous studies have described glucocorticoids (GCs) and stressors to be protective in the auditory organ against damage associated with a variety of health conditions, including noise exposure. Conversely, stressors are also predictive risk factors for hearing disorders. How both of these contrasting stress actions are linked has remained elusive. Here, we demonstrate that higher corticosterone levels during acoustic trauma in female rats is highly correlated with a decline of auditory fiber responses in high-frequency cochlear regions, and that hearing thresholds and the outer hair cell functions (distortion products of otoacoustic emissions) are left unaffected. Moreover, when GC receptor (GR) or mineralocorticoid receptor (MR) activation was antagonized by mifepristone or spironolactone, respectively, GR, but not MR, inhibition significantly and permanently attenuated trauma-induced effects on auditory fiber responses, including inner hair cell ribbon loss and related reductions of early and late auditory brainstem responses. These findings strongly imply that higher corticosterone stress levels profoundly impair auditory nerve processing, which may influence central auditory acuity. These changes are likely GR mediated as they are prevented by mifepristone.-Singer, W., Kasini, K., Manthey, M., Eckert, P., Armbruster, P., Vogt, M. A., Jaumann, M., Dotta, M., Yamahara, K., Harasztosi, C., Zimmermann, U., Knipper, M., Rüttiger, L. The glucocorticoid antagonist mifepristone attenuates sound-induced long-term deficits in auditory nerve response and central auditory processing in female rats.

Maternal Magnesium Restriction Elevates Glucocorticoid Stress and Inflammation in the Placenta and Fetus of WNIN Rat Dams.

Magnesium plays a major role in many vital functions in the body. We reported earlier that maternal magnesium restriction altered body composition, fat metabolism, and insulin resistance in WNIN rat offspring and was associated with increased glucocorticoid stress in the offspring in their later life. We hypothesize that increased glucocorticoid stress and inflammation which originate in Mg restricted rat dams is transmitted through placenta to the fetus and underlie the metabolic disturbances in the later life of the offspring. Female weanling WNIN rats received ad libitum, a control diet (MgC) or the same with 62% restriction of Mg (MgR) for 3 months, and their plasma magnesium, inflammatory cytokines, and corticosterone were determined (n = 6 per group) before mating. Following mating with control males, placentae, and fetuses were collected on gestational day 15 (GD 15) from MgC and MgR dams (eight dams from each group and three samples from each dam) and used to determine the levels of inflammatory cytokines, corticosterone, and expression of relevant genes. MgR placentae and fetuses had higher (than MgC) levels of corticosterone and proinflammatory cytokines. Expression of Hsd11b1 was increased (sixfold, p < 0.05), while that of Hsd11b2 was decreased (0.4-fold, p < 0.05) in MgR (than MgC) placenta, whereas expression of Hsd11b1was increased (3.4-fold, p < 0.05) in MgR fetus. Chronic dietary magnesium restriction in WNIN female rats increased their levels of corticosterone, leptin, and proinflammatory cytokines which appeared to be transmitted through placenta to the fetus and could thus be associated with increased stress, altered body composition, fat metabolism, and insulin resistance in the later life of the offspring.

AN INDIVIDUALIZED APPROACH TO THE EVALUATION OF CUSHING SYNDROME.

Cushing syndrome (CS) is caused by chronic exposure to excess glucocorticoids. Early recognition and treatment of hypercortisolemia can lead to decreased morbidity and mortality. The diagnosis of CS and thereafter, establishing the cause can often be difficult, especially in patients with mild and cyclic hypercortisolism. Surgical excision of the cause of excess glucocorticoids is the optimal treatment for CS. Medical therapy (steroidogenesis inhibitors, medications that decrease adrenocorticotropic hormone [ACTH] levels or glucocorticoid antagonists) and pituitary radiotherapy may be needed as adjunctive treatment modalities in patients with residual, recurrent or metastatic disease, in preparation for surgery, or when surgery is contraindicated. A multidisciplinary team approach, individualized treatment plan and long-term follow-up are important for optimal management of hypercortisolemia and the comorbidities associated with CS. ABBREVIATIONS: ACTH = adrenocorticotropic hormone; BIPSS = bilateral inferior petrosal sinus sampling; CBG = corticosteroid-binding globulin; CD = Cushing disease; CRH = corticotropin-releasing hormone; CS = Cushing syndrome; Dex = dexamethasone; DST = dexamethasone suppression test; EAS = ectopic ACTH syndrome; FDA = U.S. Food & Drug Administration; HDDST = high-dose DST; IPS/P = inferior petrosal sinus to peripheral; MRI = magnetic resonance imaging; NET = neuroendocrine tumor; PET = positron emission tomography; UFC = urinary free cortisol.

Beta-Ecdysone Protects Mouse Osteoblasts from Glucocorticoid-Induced Apoptosis In Vitro.

Glucocorticoid-induced osteoporosis is a common form of secondary osteoporosis. Glucocorticoids affect both bone formation and resorption, and prolonged glucocorticoid exposure can suppress osteoblast activities. beta-Ecdysone, found in many plants, is involved in protein synthesis, carbohydrate and lipid metabolism, and immunologic modulation. Here, we evaluated the effects of beta-ecdysone on osteoblast viability by assessing apoptosis following treatment with excess glucocorticoids. Mouse bone marrow stromal cells were induced to differentiate and grow into osteoblasts, and then treated with 10 µM glucocorticoid and 10, 1, or 0.1 µM beta-ecdysone. The expression levels of osteoblast growth and differentiation factors (runt-related transcription factor 2, osteogenic protein-1, and alkaline phosphatase), apoptosis-related genes (transformation-related protein 53, ataxia telangiectasia mutated protein, caspase-3, and caspase-8), and Akt1 and phospho-Akt (Thr308) were then assessed via alkaline phosphatase staining, acridine orange-propidium iodide staining, annexin V/PI apoptosis assay, real-time RT-PCR, and Western blot analyses. Notably, treatment with 10 µM glucocorticoid resulted in reduced osteoblast viability and the specific activity of alkaline phosphatase as well as reduced runt-related transcription factor 2, osteogenic protein-1, and alkaline phosphatase mRNA expression in vitro, indicating that glucocorticoid inhibited osteogenic differentiation. Moreover, glucocorticoid treatment yielded increased transformation-related protein 53, ataxia telangiectasia mutated protein, caspase-3, and caspase-8 expression and decreased Akt1 and phospho-Akt levels, indicating glucocorticoid-induced apoptosis. Meanwhile, beta-ecdysone inhibited glucocorticoid function, preserving the expression of Akt1 and phospho-Akt and reducing the expression of transformation-related protein 53, ataxia telangiectasia mutated protein, caspase-3, and caspase-8. Thus, beta-ecdysone prevented glucocorticoid-induced osteoblast apoptosis in vitro. These data highlight the potential for beta-ecdysone as a treatment for preventing the effects of glucocorticoid on bone growth.

Endocrine Activity of AVB, 2MR, BHA, and Their Mixtures.

Personal care products are used increasingly, resulting in growing concern concerning their potential disruption of normal hormonal functions. Recent results on the bioaccumulation of cosmetic ingredients in wildlife and humans point to the need for an in-depth analysis for endocrine activity, in particular with respect to their influence on the androgen (AR), glucocorticoid (GR), and thyroid hormone receptors (TRs). Furthermore, humans are commonly exposed simultaneously to complex mixtures of endocrine active compounds. We have therefore examined 3 frequently used cosmetic ingredients: 2-methylresorcinol (2MR), butylated hydroxyanisole (BHA) and avobenzone (AVB), for (anti)-androgen-, (anti)-glucocorticoid-, and (anti)-thyroid hormone-like activities. Their binary and ternary mixtures at EC50 or IC50 concentrations have also been examined for anti-androgen-, glucocorticoid-, and thyroid hormone-like activities. In the MDA-kb2 reporter cell line, compounds possessed anti-androgen-, glucocorticoid-, and anti-glucocorticoid-like activities (except AVB). A new cell line, GH3.TRE-Luc, was used to evaluate anti-thyroid and thyroid hormone-like activities. The combinations 2MR + BHA and 2MR + BHA + AVB have glucocorticoid-like activity: only 2MR + AVB has anti-androgen-like activity. On the other hand, binary and ternary mixtures of compounds showed no thyroid hormone-like activity. Thus, in addition to identifying new endocrine disrupting compounds, it is also necessary to determine the effects of their mixtures in order to assess fully their risk to human health.

Glucocorticoid Antagonism Reduces Insulin Resistance and Associated Lipid Abnormalities in High-Fructose-Fed Mice.

OBJECTIVES: High intake of dietary fructose causes perturbation in lipid metabolism and provokes lipid-induced insulin resistance. A rise in glucocorticoids (GCs) has recently been suggested to be involved in fructose-induced insulin resistance. The objective of the study was to investigate the effect of GC blockade on lipid abnormalities in insulin-resistant mice. METHODS: Insulin resistance was induced in mice by administering a high-fructose diet (HFrD) for 60 days. Mifepristone (RU486), a GC antagonist, was administered to HFrD-fed mice for the last 18 days, and the intracellular and extracellular GC levels, the glucocorticoid receptor (GR) activation and the expression of GC-regulated genes involved in lipid metabolism were examined. RESULTS: HFrD elevated the intracellular GC content in both liver and adipose tissue and enhanced the GR nuclear translocation. The plasma GC level remained unchanged. The levels of free fatty acids and triglycerides in plasma were elevated, accompanied by increased plasma insulin and glucose levels and decreased hepatic glycogen content. Treatment with RU486 reduced plasma lipid levels, tissue GC levels and the expression of GC-targeted genes involved in lipid accumulation, and it improved insulin sensitivity. CONCLUSIONS: This study demonstrated that HFrD-induced lipid accumulation and insulin resistance are mediated by enhanced GC in liver and adipose tissue and that GC antagonism might reduce fructose-induced lipid abnormalities and insulin resistance.

Glucocorticoids Suppress the Protective Effect of Cyclooxygenase-2-Related Signaling on Hippocampal Neurogenesis Under Acute Immune Stress.

Stress and glucocorticoids suppress adult neurogenesis in the hippocampus. However, the molecular mechanisms underlying stress-induced impairment of adult neurogenesis are poorly understood. We previously suggested that cyclooxygenase (COX)-2 is a common mediator of stresses in the brain. Here, using a lipopolysaccharide (LPS)-induced acute infectious stress model, we evaluated the roles of COX-2 and its major downstream product prostaglandin E2 (PGE2) in adult neurogenesis and the influence of glucocorticoids on COX-2-related signaling. Treatment of rats with LPS significantly decreased neurogenesis in the dentate gyrus (DG) of the hippocampus, and this inhibitory effect of LPS on neurogenesis was reversed by the glucocorticoid receptor antagonist RU486. Moreover, RU486 significantly enhanced the increase in messenger RNA (mRNA) levels of COX-2 and microsomal prostaglandin E synthase (mPGES)-1 in the hippocampus following LPS stimulation. Administration of AH6809, a selective antagonist of the PGE2 EP2 receptor, as well as NS398, a COX-2 selective inhibitor, exacerbated the suppression of proliferation of neural progenitor cells (NPCs) in the DG. Gene expression of EP1, EP2, and EP3, but not EP4, receptors was also increased following LPS stimulation. Immunohistochemical studies indicated that NPCs expressed EP2 receptor, whereas the majority of cells expressing COX-2 and mPGES-1 were mature neurons in the DG. These results suggest that acute infectious stress upregulates COX-2-related signaling in neurons in the DG, which plays a protective role in neurogenesis through EP2 receptor at least partially. In addition, LPS-induced glucocorticoids suppress this COX-2-related signaling, resulting in decreased neurogenesis.

Lung epithelial tip progenitors integrate glucocorticoid- and STAT3-mediated signals to control progeny fate.

Insufficient alveolar gas exchange capacity is a major contributor to lung disease. During lung development, a population of distal epithelial progenitors first produce bronchiolar-fated and subsequently alveolar-fated progeny. The mechanisms controlling this bronchiolar-to-alveolar developmental transition remain largely unknown. We developed a novel grafting assay to test if lung epithelial progenitors are intrinsically programmed or if alveolar cell identity is determined by environmental factors. These experiments revealed that embryonic lung epithelial identity is extrinsically determined. We show that both glucocorticoid and STAT3 signalling can control the timing of alveolar initiation, but that neither pathway is absolutely required for alveolar fate specification; rather, glucocorticoid receptor and STAT3 work in parallel to promote alveolar differentiation. Thus, developmental acquisition of lung alveolar fate is a robust process controlled by at least two independent extrinsic signalling inputs. Further elucidation of these pathways might provide therapeutic opportunities for restoring alveolar capacity.

Stress impairs the efficacy of immune stimulation by CpG-C: Potential neuroendocrine mediating mechanisms and significance to tumor metastasis and the perioperative period.

We recently reported that immune stimulation can be compromised if animals are simultaneously subjected to stressful conditions. To test the generalizability of these findings, and to elucidate neuroendocrine mediating mechanisms, we herein employed CpG-C, a novel TLR-9 immune-stimulating agent. Animals were subjected to ongoing stress (20-h of wet cage exposure) during CpG-C treatment, and antagonists to glucocorticoids, ß-adrenoceptor, COX2, or opioids were employed (RU486, nadolol, etodolac, naltrexone). In F344 rats, marginating-pulmonary NK cell numbers and cytotoxicity were studied, and the NK-sensitive MADB106 experimental metastasis model was used. In Balb/C mice, experimental hepatic metastases of the CT-26 colon tumor were studied; and in C57BL/6J mice, survival rates following excision of B16 melanoma was assessed - both mouse tumor models involved surgical stress. The findings indicated that simultaneous blockade of glucocorticoid and ß-adrenergic receptors improved CpG-C efficacy against MADB106 metastasis. In mice bearing B16 melanoma, long-term survival rate was improved by CpG-C only when employed simultaneously with blockers of glucocorticoids, catecholamines, and prostaglandins. Prolonged stress impaired CpG-C efficacy in potentiating NK activity, and in resisting MADB106 metastasis in both sexes, as also supported by in vitro studies. This latter effect was not blocked by any of the antagonists or by adrenalectomy. In the CT26 model, prolonged stress only partially reduced the efficacy of CpG-C. Overall, our findings indicate that ongoing behavioral stress and surgery can jeopardize immune-stimulatory interventions and abolish their beneficial metastasis-reducing impacts. These findings have implications for the clinical setting, which often involve psychological and physiological stress responses during immune-stimulation.