Glucocorticoid receptor and specificity protein 1 (Sp1) or Sp3 transactivate HSV-1 ICP0 promoter sequences but a GC-rich binding antibiotic, Mithramycin A, impairs reactivation from latency.

Glucocorticoid receptor (GR) activation enhances Human alpha-herpes virus 1 (HSV-1) replication and explant-induced reactivation from latency. Furthermore, GR and Krüppel-like factor 15 (KLF15) cooperatively transactivate cis-regulatory modules (CRMs) that drive expression of infected cell protein 0 (ICP0), ICP4, and ICP27. KLF and specificity protein (Sp) family members bind GC-rich or C-rich sequences and belong to the same super-family of transcription factors. Based on these observations, we hypothesized CRMs spanning the ICP0 promoter are transactivated by GR and Sp1 or Sp3. CRM-A (-800 to -635), CRM-B (-485 to -635), and CRM-D (-232 to -24), but not CRM-C, were significantly transactivated by GR, DEX, and Sp1 or Sp3 in mouse neuroblastoma cells (Neuro-2A). Mutagenesis of Sp1/Sp3 binding sites were important for transactivation of CRM-A and CRM-B. Chromatin immunoprecipitation studies revealed significantly higher levels of GR occupied ICP0 promoter sequences when Sp1 or Sp3 was over-expressed suggesting these transcriptions factors recruit GR to ICP0 CRM sequences. Mithramycin A, an antibiotic that preferentially binds GC-rich DNA and impairs Sp1/Sp3 dependent transactivation also reduced virus shedding reactivation from latency in mice latently infected with HSV-1. These studies indicate GR and certain stress-induced cellular transcription factors preferentially bind GC rich DNA, which stimulates HSV-1 gene expression and reactivation from latency in trigeminal ganglia of latently infected mice.

Dietary bile acids alleviate corticosterone-induced fatty liver and hepatic glucocorticoid receptor suppression in broiler chickens.

The aim of this study was to investigate the alleviating effects and mechanisms of bile acids (BA) on corticosterone-induced fatty liver in broiler chickens. Male Arbor Acres chickens were randomly divided into three groups: control group (CON), stress model group (CORT), and BA-treated group (CORT-BA). The CORT-BA group received a diet with 250 mg/kg BA from 21 days of age. From day 36 to 43, both the CORT and CORT-BA groups received subcutaneous injections of corticosterone to simulate chronic stress. The results indicated that BA significantly mitigated the body weight loss, liver enlargement, and hepatic lipid deposition caused by corticosterone (P < 0.05). Liver RNA-seq analysis showed that BA alleviated corticosterone-induced fatty liver by inhibiting lipid metabolism pathways, including fatty acid biosynthesis, triglyceride biosynthesis, and fatty acid transport. Additionally, BA improved corticosterone-induced downregulation of glucocorticoid receptor (GR) expression (P < 0.05). Molecular docking and cellular thermal shift assays revealed that hyodeoxycholic acid (HDCA), a major component of compound bile acids, could bind to GR and enhance its stability. In conclusion, BA alleviated corticosterone-induced fatty liver in broilers by inhibiting lipid synthesis pathways and mitigating the suppression of hepatic GR expression.

The sugar moiety in protopanaxadiol ginsenoside affects its ability to target glucocorticoid receptor to regulate lipid metabolism.

Ginsenosides are natural products with hydrophobic rings adorned with sugar molecules. The elucidation of the impact of ginsenosides structure on their activity is crucial for facilitating precision-oriented modifications, thereby enhancing their suitability for drug development. Here, utilizing an ob/ob mouse model, we demonstrated that as the number of sugar moiety on the protopanaxadiol-type ginsenosides decreased, the hypolipidemic potency increased, while the aglycon exhibited negligible activity. Mechanistically, we demonstrated the dependency of ginsenosides on the glucocorticoid receptor (GR) for the regulation of lipid metabolism. Interestingly, ginsenoside CK was found to promote the transcription of lipid metabolism-related genes via GR contrast to the effects of glucocorticoids, suggesting a unique mode of action. Furthermore, we observed that a reduction in the number of sugar molecules strengthened the binding affinity of ginsenosides to GR, as determined by microscale thermophoresis. These findings highlight the critical role of the sugar moiety in modulating the lipid-regulating capacity of ginsenosides, providing valuable insights for the development of these compounds as potential therapeutic agents.

Cortisol dynamics and GR-dependent feedback regulation in zebrafish larvae exposed to repeated stress.

Zebrafish larvae show a rapid increase in cortisol in response to acute stressors, followed by a decline. While these responses are documented, both the duration of the refractory period to repeated stressors and the role of glucocorticoid receptors (GR) in specific phases of the glucocorticoid negative feedback are still being clarified. We explored these questions using water vortices as stressors, combined with GR blockage and measurements of whole-body cortisol in zebrafish larvae subjected to single and repeated stress protocols. Cortisol levels were elevated 10 min after stress onset and returned to baseline within 30-40 min, depending on the stressor strength. In response to homotypic stress, cortisol levels rose above baseline if the second stressor occurred 60 or 120 min after the first, but not with a 30-min interval. This suggests a rapid cortisol-mediated feedback loop with a refractory period of at least 30 min. Treatment with a GR blocker delayed the return to baseline and suppressed the refractory period, indicating GR-dependent early-phase feedback regulation. These findings are consistent with mammalian models and provide a framework for further analyses of early-life cortisol responses and feedback in zebrafish larvae, ideal for non-invasive imaging and high-throughput screening.

Gene expression of kynurenine pathway enzymes in depression and following electroconvulsive therapy.

OBJECTIVE: This study aimed to investigate changes in mRNA expression of the kynurenine pathway (KP) enzymes tryptophan 2, 3-dioxygenase (TDO), indoleamine 2, 3-dioxygenase 1 and 2 (IDO1, IDO2), kynurenine aminotransferase 1 and 2 (KAT1, KAT2), kynurenine monooxygenase (KMO) and kynureninase (KYNU) in medicated patients with depression (n = 74) compared to age- and sex-matched healthy controls (n = 55) and in patients with depression after electroconvulsive therapy (ECT). Associations with mood score (24-item Hamilton Depression Rating Scale, HAM-D24), plasma KP metabolites and selected glucocorticoid and inflammatory immune markers known to regulate KP enzyme expression were also explored. METHODS: HAM-D24 was used to evaluate depression severity. Whole blood mRNA expression was assessed using quantitative real-time polymerase chain reaction. RESULTS: KAT1, KYNU and IDO2 were significantly reduced in patient samples compared to control samples, though results did not survive statistical adjustment for covariates or multiple comparisons. ECT did not alter KP enzyme mRNA expression. Changes in IDO1 and KMO and change in HAM-D24 score post-ECT were negatively correlated in subgroups of patients with unipolar depression (IDO1 only), psychotic depression and ECT responders and remitters. Further exploratory correlative analyses revealed altered association patterns between KP enzyme expression, KP metabolites, NR3C1 and IL-6 in depressed patients pre- and post-ECT. CONCLUSION: Further studies are warranted to determine if KP measures have sufficient sensitivity, specificity and predictive value to be integrated into stress and immune associated biomarker panels to aid patient stratification at diagnosis and in predicting treatment response to antidepressant therapy.

Transcriptome-wide analysis for glucocorticoid receptor-mediated mRNA decay reveals various classes of target transcripts.

The glucocorticoid receptor (GR) can bind to DNA or RNA, eliciting transcriptional activation/repression or rapid mRNA degradation, respectively. Although GR-mediated transcriptional regulation has been well-characterized, the molecular details of rapid mRNA degradation induced by glucocorticoids (GCs) are not yet fully understood. Here, we demonstrate that GC-induced GR-mediated mRNA decay (GMD) takes place in the nucleus and the cytoplasm, acting on pre-mRNAs and mRNAs. We also performed cross-linking and immunoprecipitation coupled with high-throughput sequencing (CLIP-seq) analysis for GMD factors (GR, YBX1, and HRSP12) and mRNA sequencing (mRNA-seq) analysis to identify endogenous GMD substrates. Our comprehensive CLIP-seq and mRNA sequencing analyses reveal that a range of cellular transcripts containing a common binding site for GR, YBX1, and HRSP12 are preferential targets for GMD, suggesting possible new functions of GMD in various biological events.

Ginsenoside Rh1 regulates the immune microenvironment of hepatocellular carcinoma via the glucocorticoid receptor.

OBJECTIVE: Ginsenoside Rh1 (G-Rh1) has been confirmed to inhibit the growth of breast cancer and colon cancer, but its therapeutic effect on hepatocellular carcinoma (HCC) is unclear. This study investigates the therapeutic effect of G-Rh1 on HCC as well as the underlying mechanism. METHODS: Bioinformatics methods were used to analyze glucocorticoid receptor (GR) expression and the tumor microenvironment in HCC tissues from HCC patients. The effect of G-Rh1 on HCC cells was investigated in vitro using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. The therapeutic effect of G-Rh1 was investigated in vivo using subcutaneous transplantation models in C57BL/6J and nude mice. Additionally, the proportion of infiltrating immune cells in tumors was analyzed using flow cytometry, the GR and major histocompatibility complex class-I (MHC-I) expression of HCC cells after G-Rh1 treatment was analyzed using Western blotting, and G-Rh1-treated Hepa1-6 cells were cocultured with bone marrow-derived dendritic cells and B3Z T cells to further analyze the ability of G-Rh1 to induce dendritic cell (DC) maturation and CD8+ T cell activation. RESULTS: GR expression was upregulated in HCC tissues, and high GR expression was associated with a worsened immune microenvironment. In vitro studies showed that G-Rh1 had no significant effect on the proliferation of HCC cells, while in vivo studies showed that G-Rh1 exerted antitumor effects in C57BL/6J mice but not in nude mice. Further research revealed that G-Rh1 ameliorated the immunosuppressive tumor microenvironment, thereby enhancing the antitumor effects of lenvatinib by increasing the infiltration of CD8+ T cells, mature DCs, and MHC-I-positive cells. MHC-I was upregulated by G-Rh1 via GR suppression. Moreover, overexpression of GR abolished the G-Rh1-mediated promotion of MHC-I expression in Huh7 cells, as well as the maturation of DCs and the activation of CD8+ T cells. CONCLUSION: G-Rh1 can regulate the immune microenvironment of HCC by targeting GR, thus increasing the antitumor effect of lenvatinib. Please cite this article as: Wang XH, Fu YL, Xu YN, Zhang PC, Zheng TX, Ling CQ, Feng YL. Ginsenoside Rh1 regulates the immune microenvironment of hepatocellular carcinoma via the glucocorticoid receptor. J Integr Med. 2024; Epub ahead of print.

Chronic Corticosterone Administration-Induced Mood Disorders in Laboratory Rodents: Features, Mechanisms, and Research Perspectives.

Mood disorders mainly affect the patient's daily life, lead to suffering and disability, increase the incidence rate of many medical illnesses, and even cause a trend of suicide. The glucocorticoid (GC)-mediated hypothalamus-pituitary-adrenal (HPA) negative feedback regulation plays a key role in neuropsychiatric disorders. The balance of the mineralocorticoid receptor (MR)/glucocorticoid receptor (GR) level contributes to maintaining the homeostasis of the neuroendocrine system. Consistently, a chronic excess of GC can also lead to HPA axis dysfunction, triggering anxiety, depression, memory loss, and cognitive impairment. The animal model induced by chronic corticosterone (CORT) administration has been widely adopted because of its simple replication and strong stability. This review summarizes the behavioral changes and underlying mechanisms of chronic CORT administration-induced animal models, including neuroinflammatory response, pyroptosis, oxidative stress, neuroplasticity, and apoptosis. Notably, CORT administration at different doses and cycles can destroy the balance of the MR/GR ratio to make dose-dependent effects of CORT on the central nervous system (CNS). This work aims to offer an overview of the topic and recommendations for future cognitive function research.

Captopril inhibits the overproduction of proopiomelanocortin and adrenocorticotropic hormone in the pituitary gland of male diabetic mice in close relationship with an increase in glucocorticoid receptor expression.

Prior investigation shows that diabetic patients present hypothalamus-pituitary-adrenal (HPA) axis hyperactivity related to impaired negative feedback. This study investigates the effect of Captopril on the overproduction of adrenocorticotropic hormone (ACTH) and its precursor proopiomelanocortin (POMC) in the pituitary gland of male diabetic mice. Diabetes was induced by intravenous injection of alloxan into fasted Swiss-webster mice, and the animals were treated with Captopril for 14 consecutive days, starting 7 days post-diabetes induction. Plasma corticosterone levels were evaluated by ELISA, while pituitary gland expressions of angiotensin-II type 1 receptor (AT1), angiotensin-II type 2 receptor (AT2), ACTH, Bax, Bcl-2, KI-67, POMC, and glucocorticoid receptor (GR) were evaluated using immunohistochemistry or Western blot. Diabetic mice showed pituitary gland overexpression of AT1, without altering AT2 levels, which were sensitive to Captopril treatment. Furthermore, diabetic mice presented hypercortisolism, along with an increase in the number of corticotroph cells, POMC and ACTH expression, and number of proliferative cells, and a decrease of GR expression in the pituitary gland. In addition, treatment with Captopril reduced systemic corticosterone levels, corticotroph and proliferative cell numbers, and Bcl-2, POMC, and ACTH expression in the pituitary gland of diabetic mice, besides increasing the expression of Bax and GR. In conclusion, these findings show that Captopril is a promising therapy for treating complications associated with HPA axis hyperactivity in diabetic patients, in a mechanism probably related to the downregulation of POMC production in the pituitary gland and subsequent reduction of systemic corticosterone levels.

Targeting glucocorticoid receptor signaling pathway for treatment of stress-related brain disorders.

The hypothalamic-pituitary-adrenal (HPA) axis plays a central role in governing stress-related disorders such as major depressive disorder (MDD), anxiety, and post-traumatic stress disorder. Chronic stress or early life trauma, known risk factors of disease, alter HPA axis activity and pattern of glucocorticoid (GC) secretion. These changes have consequences for physiological processes controlled by glucocorticoid receptor (GR) signaling, such as immune response and metabolism. In the brain, the aberrant GR signaling translates to altered behavior, making the GR pathway a viable target for therapies of stress-related disorders. One of the crucial elements of the pathway is FKBP5, a regulator of GR sensitivity and feedback control within the HPA axis, in which genetic variants were shown to moderate the risk of developing psychiatric conditions. The difficulty in targeting the GR-FKBP5 pathway stems from tailoring the intervention to specific brain regions and cell types, in the context of personalized genetic variations in GR and GR-associated genes, like FKBP5. The development of selective inhibitors, antagonists, and approaches based on targeted protein degradation offer insights into mechanistic aspects of disease and pave the way for improved therapy. These strategies can be employed either independently or in conjunction with conventional medications. Concomitant advancements in personalized drug screening (e.g. in vitro models exploiting induced pluripotent stem cells, iPSCs) bring the potential for optimization of therapy aiming to rescue central deficits originating from the HPA imbalance. In this mini-review, we discuss potential therapeutic strategies targeting GR signaling in stress-related disorders, with a focus on personalized approaches and advancements in drug development.

Prediction of post-ESD esophageal stricture by a nomogram and risk factor analysis of ineffective oral steroids prophylaxis.

BACKGROUND AND AIMS: Several risk models for esophageal stricture after endoscopic submucosal dissection have been developed. However, some of them did not include the use of steroids in the risk analysis. Glucocorticoid sensitivity mediated by glucocorticoid receptor expression has not been discussed in this condition. METHODS: Clinical and endoscopic characteristics were included in the logistic regression model to establish a nomogram for stenosis prediction. The score for each risk factor was estimated. Risk factors of ineffective oral steroid prophylaxis were analyzed and glucocorticoid receptor expressions were detected by immunohistochemistry. RESULTS: Three hundred fourteen patients of endoscopic submucosal dissection for esophageal superficial neoplasms were included to develop the nomogram. The circumferential range(≤ 3/4, 3/4-1 or the whole circumference), longitudinal diameter reached 4 cm (yes or not) and lesion location (the cervical and upper thoracic part, the middle thoracic part or the lower thoracic part) consisted of the nomogram. Patients have a high risk of esophageal stricture if they have a total point greater than 36. In the simplified risk score model, the corresponding cutoff score was 1. 92 patients with oral steroid prophylaxis were separately analyzed and the circumferential mucosal defect involving 7/8 or more was an independent risk factor of ineffective prevention (OR 12.2, 95%CI 5.27-28.11). The expression of glucocorticoid receptor ß was higher in the stricture group (p = 0.042 for AOD; p = 0.016 for the scoring system). CONCLUSIONS: We established a nomogram for esophageal stricture prediction. Depending on the characteristics of lesions, it is possible to estimate the risk of stricture under routine post-ESD treatments (no steroids or oral steroids). Alternative treatments should be considered if the risk is extremely high, especially for patients with mucosal defects involving 7/8 or more of circumference in which oral steroid treatment tends to be ineffective. The higher glucocorticoid receptor ß may indicate potential glucocorticoid resistance.

3,5-Dihydroxy-4-methoxybenzyl alcohol, a novel antioxidant isolated from oyster meat, inhibits the hypothalamus-pituitary-adrenal axis to regulate the stress response.

BACKGROUND: Antioxidants that can scavenge reactive oxygen in the brain and inhibit hyperactivity of the HPA axis are desirable. AIMS: We investigated the cerebral translocation of the antioxidant 3,5-dihydroxy-4-methoxybenzyl alcohol (DHMBA) and the effects of DHMBA administration on the hypothalamus-pituitary-adrenal (HPA) axis in stress-loaded rats. METHODS: Experiment 1: Plasma and brain DHMBA concentrations were measured over time after oral DHMBA administration to female B6 mice. Experiment 2: Female Wistar Imamichi rats were used. The normal group was not subjected to stress. The stress, DHMBA, and vitamin E groups were subjected to individual and overcrowding stress. Brain and hippocampal 8-hydroxy-2'-deoxyguanosine levels, hippocampal glucocorticoid receptor-α levels, plasma corticosterone levels and RNA levels of glutathione peroxidase 4, catalase, and glutathione reductase in the hippocampus were measured. RESULTS: In Experiment 1, DHMBA was not detected in the plasma or brain before DHMBA administration but was detected in both after administration. In Experiment 2, brain and hippocampal 8-hydroxy-2'-deoxyguanosine levels and plasma corticosterone levels were significantly lower in the DHMBA than in the stress group. Glucocorticoid receptor-α levels were higher in the DHMBA than in the stress group. DHMBA increased RNA levels of antioxidant enzymes in the hippocampus. CONCLUSION: DHMBA was translocated to the brain after administration. DHMBA administration decreased 8-hydroxy-2'-deoxyguanosine levels in the brain and hippocampus, increased hippocampal glucocorticoid receptor-α levels, and decreased the plasma corticosterone concentration, suggesting that DHMBA inhibits hyperactivity of the HPA axis. Nrf2 pathway activity induced by DHMBA resulted in increased antioxidant enzyme levels in the hippocampus.

Protopanaxadiol synergizes with glucocorticoids to enhance the therapeutic effect in adriamycin-induced nephrotic syndrome.

To date, glucocorticoids remain the mainstay of treatment of nephrotic syndrome (NS). However, serious side effects and development of drug-resistance following long-term use limit the application of glucocorticoids. Protopanaxadiol (PPD) possesses activity of dissociating transactivation from transrepression by glucocorticoid receptor (GR), which may serve as a potential selective GR modulator. However, steroid-like effects of PPD in vivo are unclear and not defined. How to translate PPD into clinical practice remains to be explored. The current study explored the renoprotection and potential mechanism of PPD and its combination with steroid hormones using adriamycin-induced NS rats. Adriamycin was given intravenously to rats to induce nephropathy. The determination of proteinuria, biochemical changes and inflammatory cytokines were performed, and pathological changes were examined by histopathological examination. Immunostaining and PCR were used to analyze the expression of interesting proteins and genes. The results showed that PPD, alone and in combination with prednisone, efficiently alleviate the symptoms of NS, attenuate nephropathy, improve adriamycin-induced podocyte injury by reducing desmin and increasing synaptopodin expression. In addition, the combined treatment reduced the expression of NF-κB protein and mRNA, as well as cytokine levels, and yet increased the expression of GR protein and mRNA. PPD modulated the transactivation of GR, manifested as repressing TAT, PEPCK and ANGPTL4 mRNA expressions mediated by GR. Meanwhile, PPD inhibited elevation of blood glucose and immune organ atrophy induced by prednisone. In summary, PPD increases the therapeutic effect of prednisone in NS while effectively prevents or decreases the appearance of side effects of glucocorticoids.

Ginsenosides modulate hypothalamic-pituitary-adrenal function by inhibiting FKBP51 on glucocorticoid receptor to ameliorate depression in mice exposed to chronic unpredictable mild stress.

Depression, which affects millions of individuals worldwide, is associated with glucocorticoid (GC) impairment, with the FKBP51 protein playing a pivotal role. Ginsenosides, extracted from the root of Panax ginseng C.A. Mey, have demonstrated the potential to mitigate depression associated with GC dysregulation. This study evaluated the therapeutic efficacy of ethanol extract of P. ginseng (PG) in treating depression and its underlying FKBP51-linked mechanism. Using chronic unpredictable stress, a depression model was developed in Kunming mice to test the efficacy of PG by observing changes in behaviors and protein expression in depressed mice. The mechanism of action was investigated through transfection with HEK293T cells. Depressed mice treated with PG demonstrated notable improvements: the rate of weight loss was reduced, sucrose preference and open-field activity were enhanced, and the rate of apoptosis in hippocampal cells was decreased. Additionally, the HPA axis function appeared to be restored. These physiological adjustments coincided with an increase in GR levels and a decrease in FKBP51 levels. Altogether, these results suggested that PG treatment effectively alleviates depressive symptoms in mice. PG also moderated FKBP51-GR interaction, lessening FKBP51's restraint on GR nuclear entry. This modulation may enhance the sensitivity of the GR response, reinforcing the negative feedback regulation of the HPA axis and thereby reducing depressive symptoms in mice. These findings highlight the potential of PG as a promising curative treatment for depression, providing a basis for the development of innovative treatments targeting the FKBP51-GR pathway.

Glucocorticoid receptor response and glucocorticoid-induced leucine zipper expression in neutrophils of critically ill patients with traumatic and non-traumatic brain injury.

Objective: Critically ill patients, including those with brain injuries (BI), are frequently hospitalized in an intensive care unit (ICU). As with other critical states, an adequate stress response is essential for survival. Research on the hypothalamic-pituitary-adrenal gland (HPA) axis function in BI has primarily focused on assessing ACTH and cortisol levels. However, the immunological, metabolic, and hemodynamic effects of glucocorticoids (GCs) are mediated through the glucocorticoid receptor (GCR), a ubiquitously distributed intracellular receptor protein. Data on GCR-α expression and its signaling in acute BI injury are lacking. Methods: We designed a prospective observational study, carried out in one academic multi-disciplinary ICU. Forty-two critically ill patients with acute (BI)were included. These patients suffered from traumatic BI (N= 20), subarachnoid hemorrhage (N= 12), intracranial hemorrhage (N= 7), or ischemic stroke (N= 3). All patients were steroid-free. Twenty-four age and sex-matched healthy controls were used for comparison. Results: Expression of GCR-α and the glucocorticoid-inducible leucine zipper (GILZ), serum cortisol, interleukins (IL) 6, 8, 10 and TNF- α, and the BI biomarkers glial fibrillary acidic protein (GFAP) and total Tau were measured on ICU admission (within 48 hours) and 5-7 days from admission. Compared to healthy controls, in the critically ill patients with BI, GCR-α mRNA expression was significantly downregulated on admission, and after 5-7 days in the ICU (2.3-fold, p<0.05 and 2.6-fold, p<0.01, respectively). Even though GCR-α was downregulated, its downstream gene, GILZ, was expressed at the same levels as in normal controls on admission and was significantly upregulated 5-7 days following admission (2-fold, p<0.001). TNF-α levels were undetectable at both time-points. GCR-α expression levels inversely correlated with IL-6. The levels of cortisol and the BI biomarkers did not differ between the 2 time-points. Conclusions: We provide novel evidence on the downregulated expression and upregulated signaling of the ligand-binding and functionally active GCR-α isoform in the polymorphonuclear neutrophils (PMNs) of critically ill patients with BI. The increased GILZ expression indicates an increased GC sensitivity in the PMNs of BI critically ill patients.

Early metabolic and transcriptomic regulation in rainbow trout (Oncorhynchus mykiss) liver by 11-deoxycorticosterone through two corticosteroid receptors pathways.

Cortisol hormone is considered the main corticosteroid in fish stress, acting through glucocorticoid (GR) or mineralocorticoid (MR) receptor. The 11-deoxycorticosterone (DOC) corticosteroid is also secreted during stress and could complement the cortisol effects, but this still not fully understood. Hence, we evaluated the early transcriptomic response of rainbow trout (Oncorhynchus mykiss) liver by DOC through GR or MR. Thirty juvenile trout were pretreated with an inhibitor of endogenous cortisol synthesis (metyrapone) by intraperitoneal injection in presence or absence of GR (mifepristone) and MR (eplerenone) pharmacological antagonists for one hour. Then, fish were treated with a physiological DOC dose or vehicle (DMSO-PBS1X as control) for three hours (n = 5 per group). We measured several metabolic parameters in plasma, together with the liver glycogen content. Additionally, we constructed cDNA libraries from liver of each group, sequenced by HiseqX Illumina technology and then analyzed by RNA-seq. Plasma pyruvate and cholesterol levels decreased in DOC-administered fish and only reversed by eplerenone. Meanwhile, DOC increased liver glycogen contents depending on both corticosteroid receptor pathways. RNA-seq analysis revealed differential expressed transcripts induced by DOC through GR (448) and MR (1901). The enriched biological processes to both were mainly related to stress response, protein metabolism, innate immune response and carbohydrates metabolism. Finally, we selected sixteen genes from enriched biological process for qPCR validation, presenting a high Pearson correlation (0.8734 average). These results describe novel physiological effects of DOC related to early metabolic and transcriptomic responses in fish liver and differentially modulated by MR and GR.

Does the stress axis mediate behavioural flexibility in a social cichlid, Neolamprologus pulcher?

Behavioural flexibility plays a major role in the way animals cope with novel situations, and physiological stress responses are adaptive and highly efficient mechanisms to cope with unpredictable events. Previous studies investigating the role of stress responses in mediating behavioural flexibility were mostly done in laboratory rodents using stressors and cognitive challenges unrelated to the ecology of the species. To better understand how stress mediates behavioural flexibility in a natural context, direct manipulations of the stress response and cognitive tests in ecologically relevant contexts are needed. To this aim, we pharmacologically blocked glucocorticoid receptors (GR) in adult Neolamprologus pulcher using a minimally invasive application of a GR antagonist. GR blockade prevents the recovery after a stressful event, which we predicted to impair behavioural flexibility. After the application of the GR antagonist, we repeatedly exposed fish to a predator and tested their behavioural flexibility using a detour task, i.e. fish had to find a new, longer route to the shelter when the shortest route was blocked. While the latencies to find the shelter were not different between treatments, GR blocked fish showed more failed attempts during the detour tasks than control fish. Furthermore, weak performance during the detour tasks was accompanied by an increase of fear related behaviours. This suggests that blocking GR changed the perception of fear and resulted in an impaired behavioural flexibility. Therefore, our results support a potential link between the capacity to recover from stressors and behavioural flexibility in N. pulcher with potential consequences for an effective and adaptive coping with changing environments.

Dexamethasone Inhibits the Growth of B-Lymphoma Cells by Downregulating DOT1L.

BACKGROUND: Dexamethasone (Dex), a synthetic glucocorticoid that acts by binding to the glucocorticoid receptor (GR), has been widely applied to treat leukemia and lymphoma; however, the precise mechanism underlying Dex action is still not well elucidated. DOT1L, a histone H3-lysine79 (H3K79) methyltransferase, has been linked to multiple cancer types, particularly mixed lineage leukemia (MLL) gene rearranged leukemia, but its contribution to lymphoma is yet to be delineated. Analysis from the TCGA database displayed that DOT1L was highly expressed in lymphoma and leukemia. RESULTS: We initially demonstrated that DOT1L served as a new target gene controlled by GR, and the downregulation of DOT1L was critical for the killing of B-lymphoma cells by Dex. Further study revealed that Dex had no impact on the transcriptional activity of the DOT1L promoter, rather it reduced the mRNA level of DOT1L at the posttranscriptional level. In addition, knockdown of DOT1L remarkably inhibited the B-lymphoma cell growth. CONCLUSIONS: Overall, our findings indicated that DOT1L may serve as a potential drug target and a promising biomarker of Dex sensitivity when it comes to treating B lymphoma.

Salt-sensitive hypertension in GR mutant rats is associated with altered plasma polyunsaturated fatty acid levels and aortic vascular reactivity.

In humans, glucocorticoid resistance is attributed to mutations in the glucocorticoid receptor (GR). Most of these mutations result in decreased ligand binding, transactivation, and/or translocation, albeit with normal protein abundances. However, there is no clear genotype‒phenotype relationship between the severity or age at disease presentation and the degree of functional loss of the receptor. Previously, we documented that a GR+/- rat line developed clinical features of glucocorticoid resistance, namely, hypercortisolemia, adrenal hyperplasia, and salt-sensitive hypertension. In this study, we analyzed the GR+/em4 rat model heterozygously mutant for the deletion of exon 3, which encompasses the second zinc finger, including the domains of DNA binding, dimerization, and nuclear localization signals. On a standard diet, mutant rats exhibited a trend toward increased corticosterone levels and a normal systolic blood pressure and heart rate but presented with adrenal hyperplasia. They exhibited increased adrenal soluble epoxide hydroxylase (sEH), favoring an increase in less active polyunsaturated fatty acids. Indeed, a significant increase in nonactive omega-3 and omega-6 polyunsaturated fatty acids, such as 5(6)-DiHETrE or 9(10)-DiHOME, was observed with advanced age (10 versus 5 weeks old) and following a switch to a high-salt diet accompanied by salt-sensitive hypertension. In thoracic aortas, a reduced soluble epoxide hydrolase (sEH) protein abundance resulted in altered vascular reactivity upon a standard diet, which was blunted upon a high-salt diet. In conclusion, mutations in the GR affecting the ligand-binding domain as well as the dimerization domain resulted in deregulated GR signaling, favoring salt-sensitive hypertension in the absence of obvious mineralocorticoid excess.

Gypenoside LXXV Alleviates Colitis by Reprograming Macrophage Polarization via the Glucocorticoid Receptor Pathway.

An imbalance in the macrophage phenotype is closely related to various inflammatory diseases. Here, we discovered that gypenoside LXXV (GP-75), a type of saponin from Gynostemma pentaphyllum, can reprogram M1-like macrophages into M2-like ones. On a mechanistic level, GP-75 inhibits NF-κB-COX2 signaling by targeting the glucocorticoid receptor (GR). Administration of GP-75, either orally or by intraperitoneal injection, significantly alleviates ulcerative colitis in mice, a pathogenesis associated with macrophage polarization. Clodronate liposomes, which deplete macrophages in mice, as well as GR antagonist RU486, abrogate the anticolitis effect of GP-75, thus confirming the pivotal role of macrophages in GP-75 function. We also showed that GP-75 has no toxicity in mice. Overall, this is the first report that demonstrates the effect of GP-75 on macrophage reprograming and as an agent against colitis. Because G. pentaphyllum is gaining popularity as a functional food, our findings offer new perspectives on the use of gypenosides as potential nutraceuticals for medical purposes.