Brain corticosteroid receptor balance in health and disease

The Impact of Developmental Timing for Stress and Recovery

Stress can have lasting effects on the brain and behavior. Delineating the impact of stress on the developing brain is fundamental for understanding mechanisms through which stress induces persistent effects on behavior that can lead to psychopathology. The growing field of translational developmental neuroscience has revealed a significant role of the timing of stress on risk, resilience, and neuroplasticity. Studies of stress across species have provided essential insight into the mechanisms by which the brain changes and the timing of those changes on outcome. In this article, we review the neurobiological effects of stress and propose a model by which sensitive periods of neural development interact with stressful life events to affect plasticity and the effects of stress on functional outcomes. We then highlight how early-life stress can alter the course of brain development. Finally, we examine mechanisms of buffering against early-life stress that may promote resilience and positive outcomes. The findings are discussed in the context of implications for early identification of risk and resilience factors and development of novel interventions that target the biological state of the developing brain to ultimately ameliorate the adverse consequences of stress during childhood and adolescence.

The janus face of stress on reproduction: from health to disease

Parenthood is a fundamental feature of all known life. However, infertility has been recognized as a public health issue worldwide. But even when the offspring are conceived, in utero problems can lead to immediate (abortion), early (birth), and late (adulthood) consequences. One of the most studied factors is stress. However, stress response is, per se, of adaptive nature allowing the organism to cope with challenges. Stressors lead to deterioration if one is faced with too long lasting, too many, and seemingly unsolvable situations. In stress adaptation the hypothalamus-pituitary-adrenocortical axis and the resulting glucocorticoid elevation are one of the most important mechanisms. At cellular level stress can be defined as an unbalance between production of free radicals and antioxidant defenses. Oxidative stress is widely accepted as an important pathogenic mechanism in different diseases including infertility. On the other hand, the goal of free radical production is to protect the cells from infectious entities. This review aims to summarize the negative and positive influence of stress on reproduction as a process leading to healthy progeny. Special emphasis was given to the balance at the level of the organism and cells.

Temporal gene expression in the hippocampus and peripheral organs to endotoxin-induced systemic inflammatory response in caspase-1-deficient mice

OBJECTIVES

Caspase-1 (casp1), a key protease involved in the systemic inflammatory response syndrome (SIRS), controls the brain expression of a set of eight genes: Nos2 and Ptgs2 (nitric oxide synthase 2 and prostaglandin-endoperoxide synthase 2, two inducible enzymes), Cxcl1 and Cxcl10 (C-X-C motif chemokine ligand 1 and ligand 10), Tgtp and Gbp2 (T cell-specific GTPase 1 and guanylate-binding protein 2, two GTPases), Adamts1 (a disintegrin-like and metallopeptidase with thrombospondin type 1 motif, 1, a metalloprotease) and Il1rn (interleukin-1 receptor antagonist). Our objective was to ascertain whether casp1 also controlled the peripheral expression of these genes and, if so, to compare their central versus peripheral patterns of gene expression in immune and endocrine tissues during SIRS.

METHODS

Wild-type (wt) and casp1 knockout (casp1(-/-)) mice were injected with either saline or a high dose of endotoxin/lipopolysaccharide (LPS; 800 μg/mice i.p.). Saline-injected mice were immediately euthanized after injection, whereas LPS-injected mice were sacrificed 6 and 12 h after LPS administration. Hippocampal, splenic and adrenal gene expressions were determined by real-time PCR.

RESULTS

Overall, casp1(-/-) mice showed a lower inflammatory response than wt mice. The expression levels of powerful proinflammatory factors such as Nos2 and Ptgs2 was reduced in casp1(-/-) mice. Moreover, a hierarchical clustering analysis aimed at studying patterns of gene coexpression revealed large alterations in the hippocampal pattern of casp1(-/-) mice. Surprisingly, the expression of Adamts1 was increased in the hippocampus and adrenals of casp1(-/-) mice.

CONCLUSIONS

The resilience of casp1(-/-) mice to SIRS lethality is associated with a lower inflammatory response, loss of hippocampal gene coexpression patterns, and increased hippocampal Adamts1 gene expression. The latter might be beneficial for casp1(-/-) mice, since ADAMTS1 is likely to play a role in neuronal plasticity. The mechanisms described here may help the development of either novel biomarkers or therapeutic targets against SIRS/sepsis.

Dissection of glucocorticoid receptor-mediated inhibition of the hypothalamic-pituitary-adrenal axis by gene targeting in mice

Negative feedback regulation of glucocorticoid (GC) synthesis and secretion occurs through the function of glucocorticoid receptor (GR) at sites in the hypothalamic-pituitary-adrenal (HPA) axis, as well as in brain regions such as the hippocampus, prefrontal cortex, and sympathetic nervous system. This function of GRs in negative feedback coordinates basal glucocorticoid secretion and stress-induced increases in secretion that integrate GC production with the magnitude and duration of the stressor. This review describes the effects of GR loss along major sites of negative feedback including the entire brain, the paraventricular nucleus of the hypothalamus (PVN), and the pituitary. In genetic mouse models, we evaluate circadian regulation of the HPA axis, stress-stimulated neuroendocrine response and behavioral activity, as well as the integrated response of organism metabolism. Our analysis provides information on contributions of region-specific GR-mediated negative feedback to provide insight in understanding HPA axis dysregulation and the pathogenesis of psychiatric and metabolic disorders.

Perspectives on stress resilience and adolescent neurobehavioral function

Interest in adolescence as a crucial stage of neurobehavioral maturation is growing, as is the concern of how stress may perturb this critical period of development. Though it is well recognized that stress-related vulnerabilities increase during adolescence, not all adolescent individuals are uniformly affected by stress nor do stressful experiences inevitability lead to negative outcomes. Indeed, many adolescents show resilience to stress-induced dysfunctions. However, relatively little is known regarding the mechanisms that may mediate resilience to stress in adolescence. The goal of this brief review is to bring together a few separate, yet related lines of research that highlight specific variables that may influence stress resilience during adolescence, including early life programming of the hypothalamic-pituitary-adrenal (HPA) axis, stress inoculation, and genetic predisposition. Though we are far from a clear understanding of the factors that mediate resistance to stress-induced dysfunctions, it is imperative that we identify and delineate these aspects of resilience to help adolescents reach their full potential, even in the face of adversity.

Glucocorticoids, epigenetic control and stress resilience

Glucocorticoid hormones play a pivotal role in the response to stressful challenges. The surge in glucocorticoid hormone secretion after stress needs to be tightly controlled with characteristics like peak height, curvature and duration depending on the nature and severity of the challenge. This is important as chronic hyper- or hypo-responses are detrimental to health due to increasing the risk for developing a stress-related mental disorder. Proper glucocorticoid responses to stress are critical for adaptation. Therefore, the tight control of baseline and stress-evoked glucocorticoid secretion are important constituents of an organism's resilience. Here, we address a number of mechanisms that illustrate the multitude and complexity of measures safeguarding the control of glucocorticoid function. These mechanisms include the control of mineralocorticoid (MR) and glucocorticoid receptor (GR) occupancy and concentration, the dynamic control of free glucocorticoid hormone availability by corticosteroid-binding globulin (CBG), and the control exerted by glucocorticoids at the signaling, epigenetic and genomic level on gene transcriptional responses to stress. We review the beneficial effects of regular exercise on HPA axis and sleep physiology, and cognitive and anxiety-related behavior. Furthermore, we describe that, possibly through changes in the GABAergic system, exercise reduces the impact of stress on a signaling pathway specifically in the dentate gyrus that is strongly implicated in the behavioral response to that stressor. These observations underline the impact of life style on stress resilience. Finally, we address how single nucleotide polymorphisms (SNPs) affecting glucocorticoid action can compromise stress resilience, which becomes most apparent under conditions of childhood abuse.

Blunted glucocorticoid and mineralocorticoid sensitivity to stress in people with diabetes

Psychological stress may contribute to type 2 diabetes but mechanisms are still poorly understood. In this study, we examined whether stress responsiveness is associated with glucocorticoid and mineralocorticoid sensitivity in a controlled experimental comparison of people with type 2 diabetes and non-diabetic participants. Thirty-seven diabetes patients and 37 healthy controls underwent psychophysiological stress testing. Glucocorticoid (GR) and mineralocorticoid sensitivity (MR) sensitivity were measured by dexamethasone- and prednisolone-inhibition of lipopolysaccharide (LPS)-induced interleukin (IL) 6 levels, respectively. Blood pressure (BP) and heart rate were monitored continuously, and we periodically assessed salivary cortisol, plasma IL-6 and monocyte chemotactic protein (MCP-1). Following stress, both glucocorticoid and mineralocorticoid sensitivity decreased among healthy controls, but did not change in people with diabetes. There was a main effect of group on dexamethasone (F(1,74)=6.852, p=0.013) and prednisolone (F(1,74)=7.295, p=0.010) sensitivity following stress at 45 min after tasks. People with diabetes showed blunted stress responsivity in systolic BP, diastolic BP, heart rate, IL-6, MCP-1, and impaired post-stress recovery in heart rate. People with Diabetes had higher cortisol levels as measured by the total amount excreted over the day and increased glucocorticoid sensitivity at baseline. Our study suggests that impaired stress responsivity in type-2 diabetes is in part due to a lack of stress-induced changes in mineralocorticoid and glucocorticoid sensitivity.

The association of proopiomelanocortin polymorphisms with the risk of major depressive disorder and the response to antidepressants via interactions with stressful life events

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis is among the most consistent neuroendocrine abnormalities in major depressive disorder (MDD). The peptide adrenocorticotropin hormone (ACTH) mediates HPA axis function during stress and is encoded by the proopiomelanocortin (POMC) gene polycistronically. After screening 39 POMC polymorphisms, we evaluated the association of polymorphisms with susceptibility to MDD in 145 MDD patients and 193 normal subjects; in patients, we also evaluated the response to treatment with antidepressants. Additionally, we investigated the role of gene-environment interaction between POMC haplotypes and stressful life events (SLE) in the treatment response. Although genotypes and haplotypes were not significantly associated with the risk of MDD, non-remitters were more likely to carry haplotype 1 (ht1) and to have no ht2 than were remitters (corrected P = 0.010-0.035). Although observations were limited in patients without SLE, a significant haplotype-SLE interaction was observed (P = 0.020). Additionally, at 1, 2, and 8 weeks of treatment, the 21-item Hamilton Depression Rating scores of MDD subjects with POMC ht2 were significantly (P = 0.003-0.044) lower than those of patients with ht1 in subjects those did not experience SLE. MDD subjects possessing POMC ht2 achieved remission significantly (P = 0.013; survival analysis) faster than patients with ht1. This study suggests that POMC haplotypes, via an interaction with SLE, are associated with antidepressant treatment outcomes in MDD patients. Regarding SLE, haplotypes of the POMC gene could be useful markers for predicting the response to antidepressant treatment in MDD patients.

Modifications of glucocorticoid receptors mRNA expression in the hypothalamic-pituitary-adrenal axis in response to early-life stress in female Japanese quail

Stress exposure during early-life development can programme individual brain and physiology. The hypothalamic-pituitary-adrenal (HPA) axis is one of the primary targets of this programming, which is generally associated with a hyperactive HPA axis, indicative of a reduced negative-feedback. This reduced feedback efficiency usually results from a reduced level of the glucocorticoid receptor (GR) and/or the mineralocorticoid receptor (MR) within the HPA axis. However, a few studies have shown that early-life stress exposure results in an attenuated physiological stress response, suggesting an enhance feedback efficiency. In the present study, we aimed to determine whether early-life stress had long-term consequences on GR and MR levels in quail and whether the effects on the physiological response to acute stress observed in prenatally stressed individuals were underpinned by changes in GR and/or MR levels in one or more HPA axis components. We determined GR and MR mRNA expression in the hippocampus, hypothalamus and pituitary gland in quail exposed to elevated corticosterone during prenatal development, postnatal development, or both, and in control individuals exposed to none of the stressors. We showed that prenatal stress increased the GR:MR ratio in the hippocampus, GR and MR expression in the hypothalamus and GR expression in the pituitary gland. Postnatal stress resulted in a reduced MR expression in the hippocampus. Both early-life treatments permanently affected the expression of both receptor types in HPA axis regions. The effects of prenatal stress are in accordance with a more efficient negative-feedback within the HPA axis and thus can explain the attenuated stress response observed in these birds. Therefore, these changes in receptor density or number as a consequence of early-life stress exposure might be the mechanism that allows an adaptive response to later-life stressful conditions.

Impact of Adiposity and Fat Distribution on the Dynamics of Adrenocorticotropin and Cortisol Rhythms

Obesity impacts many hormonal systems, including pituitary hormones, as well as insulin and leptin. In this review we discuss articles which investigate the influence of obesity on the hypothalamic-pituitary-adrenal (HPA) axis. Different techniques have been used to assess the function of the HPA-axis in obesity, including measuring fasting and/or late evening levels of adrenocorticotropic hormone (ACTH) and (free) cortisol in plasma and saliva, studying feedback with dexamethasone or cortisol, and evaluating responsiveness of the system to corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) or ACTH 1-29. In addition, more elaborate studies investigated 24-h secretion patterns, analyzed with deconvolution techniques to quantitate pulsatile secretion rates of cortisol and less often ACTH. Other investigators used timed infusions of labeled cortisol for the estimation of the 24-h secretion rate, clearance rate and distribution volume. Many studies relied on the 24-h urinary excretion of free cortisol, but for quantitation of the 24-h secretion, measurement of all cortisol-derived metabolites is required. Several studies have applied modern liquid chromatography-tandem-mass spectrometry techniques to measure these metabolites. The picture emerging from all these studies is that, first, ACTH secretion is amplified, likely via enhanced forward drive; and, second, serum cortisol levels are normal or even low, associated with a normal 24-h cortisol secretion per liter distribution volume determined by deconvolution, but enhanced when based on the increased total distribution volume associated with obesity. Increased cortisol secretion was also established by isotope dilution studies and reports based on the measurement of all urinary cortisol metabolites. The responsiveness of the adrenal gland to ACTH is diminished. The studies do not address quantitative aspects of cortisol-cortisone metabolism on individual organs, including liver, central and peripheral fat, intestine, skin, and muscle.

Physiological basis for the etiology, diagnosis, and treatment of adrenal disorders: Cushing's syndrome, adrenal insufficiency, and congenital adrenal hyperplasia

The hypothalamic-pituitary-adrenal (HPA) axis is a classic neuroendocrine system. One of the best ways to understand the HPA axis is to appreciate its dynamics in the variety of diseases and syndromes that affect it. Excess glucocorticoid activity can be due to endogenous cortisol overproduction (spontaneous Cushing's syndrome) or exogenous glucocorticoid therapy (iatrogenic Cushing's syndrome). Endogenous Cushing's syndrome can be subdivided into ACTH-dependent and ACTH-independent, the latter of which is usually due to autonomous adrenal overproduction. The former can be due to a pituitary corticotroph tumor (usually benign) or ectopic ACTH production from tumors outside the pituitary; both of these tumor types overexpress the proopiomelanocortin gene. The converse of Cushing's syndrome is the lack of normal cortisol secretion and is usually due to adrenal destruction (primary adrenal insufficiency) or hypopituitarism (secondary adrenal insufficiency). Secondary adrenal insufficiency can also result from a rapid discontinuation of long-term, pharmacological glucocorticoid therapy because of HPA axis suppression and adrenal atrophy. Finally, mutations in the steroidogenic enzymes of the adrenal cortex can lead to congenital adrenal hyperplasia and an increase in precursor steroids, particularly androgens. When present in utero, this can lead to masculinization of a female fetus. An understanding of the dynamics of the HPA axis is necessary to master the diagnosis and differential diagnosis of pituitary-adrenal diseases. Furthermore, understanding the pathophysiology of the HPA axis gives great insight into its normal control.

Role of adult hippocampal neurogenesis in stress resilience

There is a growing appreciation that adult hippocampal neurogenesis plays a role in emotional and cognitive processes related to psychiatric disorders. Although many studies have investigated the effects of stress on adult hippocampal neurogenesis, most have not focused on whether stress-induced changes in neurogenesis occur specifically in animals that are more resilient or more susceptible to the behavioural and neuroendocrine effects of stress. Thus, in the present review we explore whether there is a clear relationship between stress-induced changes in adult hippocampal neurogenesis, stress resilience and antidepressant-induced recovery from stress-induced changes in behaviour. Exposure to different stressors is known to reduce adult hippocampal neurogenesis, but some stressors have also been shown to exert opposite effects. Ablation of neurogenesis does not lead to a depressive phenotype, but it can enhance responsiveness to stress and affect stress susceptibility. Monoaminergic-targeted antidepressants, environmental enrichment and adrenalectomy are beneficial for reversing stress-induced changes in behaviour and have been shown to do so in a neurogenesis-dependant manner. In addition, stress and antidepressants can affect hippocampal neurogenesis, preferentially in the ventral hippocampus. Together, these data show that adult hippocampal neurogenesis may play a role in the neuroendocrine and behavioural responses to stress, although it is not yet fully clear under which circumstances neurogenesis promotes resilience or susceptibility to stress. It will be important that future studies carefully examine how adult hippocampal neurogenesis can contribute to stress resilience/susceptibility so that it may be appropriately exploited for the development of new and more effective treatments for stress-related psychiatric disorders.

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Ablation of adult hippocampal NG can affect stress susceptibility.

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Increased hippocampal NG is associated with both susceptibility and resilience.

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Adult hippocampal NG can influence stress-induced alterations in HPA-axis activity.

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Behavioural effects of some but not all antidepressants are neurogenesis-dependent.

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Stress and antidepressants can affect NG preferentially in the ventral hippocampus.

Effects of HIP in protection of HSP70 for stress-induced cardiomyocytes injury and its glucorticoid receptor pathway

Moderate levels of stress can be beneficial to health, while stress overload can cause injury or contribute to diseases. Despite a number of studies of adaptation or stress damage, the mechanisms of adaptation and stress damage remain far from clear. The effect and mechanisms of adaptation on cardiomyocytes damage caused by stress overload are discussed in this study. Data showed that mild repeated stress mitigated stress overload-induced cardiomyocyte injury both in an animal model of restraint stress and in H9C2 cells with GC (glucocorticoid) treatment. HSP70, HIP expression and interaction between HSP70 and HIP increased during adaptation induced by mild stress both in animals and H9C2 cells. Overexpression or inhibition of HSP70 in H9C2 cells with pCDNA-3.1-Hsp70 or KNK437 (HSP70 inhibitor) showed that HSP70 can protect H9C2 cells from GC-induced cell damage. A luciferase assay showed that Hsp70 plays its protective role through inhibition of GR transcription activity dependent on the interaction with HIP. These results indicated that HSP70 may promote adaptation with its interacting protein HIP, and increased levels of HSP70 and its interacting protein HIP during adaptation may play a protective role on stress-overload-induced cardiomyocyte injury.

Upregulation of nucleoside triphosphate diphosphohydrolase-1 and ecto-5'-nucleotidase in rat hippocampus after repeated low-dose dexamethasone administration

Although dexamethasone (DEX), a synthetic glucocorticoid receptor (GR) analog with profound effects on energy metabolism, immune system, and hypothalamic-pituitary-adrenal axis, is widely used therapeutically, its impact on the brain is poorly understood. The aim of the present study was to explore the effect of repeated low-dose DEX administration on the activity and expression of the ectonucleotidase enzymes which hydrolyze and therefore control extracellular ATP and adenosine concentrations in the synaptic cleft. Ectonucleotidases tested were ectonucleoside triphosphate diphosphohydrolase 1-3 (NTPDase1-3) and ecto-5'-nucleotidase (eN), whereas the effects were evaluated in two brain areas that show different sensitivity to glucocorticoid action, hippocampus, and cerebral cortex. In the hippocampus, but not in cerebral cortex, modest level of neurodegenerative changes as well as increase in ATP, ADP, and AMP hydrolysis and upregulation of NTPDase1 and eN mRNA expression ensued under the influence of DEX. The observed pattern of ectonucleotidase activation, which creates tissue volume with enhanced capacity for adenosine formation, is the hallmark of the response after different insults to the brain.

Circadian characteristics of permissive and suppressive effects of cortisol and their role in homeostasis and the acute inflammatory response

In this work we explore a semi-mechanistic model that considers cortisol's permissive and suppressive effects through the regulation of cytokine receptors and cytokines respectively. Our model reveals the proactive role of cortisol during the resting period and its reactive character during the body's activity phase. Administration of an acute LPS dose during the night, when cortisol's permissive effects are higher than suppressive, leads to increased cytokine levels compared to LPS administration at morning when cortisol's suppressive effects are higher. Interestingly, our model presents a hysteretic behavior where the relative predominance of permissive or suppressive effects results not only from cortisol levels but also from the previous states of the model. Therefore, for the same cortisol levels, administration of an inflammatory stimulus at cortisol's ascending phase, that follows a time period where cytokine receptor expression is elevated ultimately sensitizing the body for the impending stimulus, leads to higher cytokine expression compared to administration of the same stimulus at cortisol's descending phase.

Early life stress and serotonin transporter gene variation interact to affect the transcription of the glucocorticoid and mineralocorticoid receptors, and the co-chaperone FKBP5, in the adult rat brain

The short allelic variant of the serotonin transporter (5-HTT) promoter-linked polymorphic region (5-HTTLPR) has been associated with the etiology of major depression by interaction with early life stress (ELS). A frequently observed endophenotype in depression is the abnormal regulation of levels of stress hormones such as glucocorticoids. It is hypothesized that altered central glucocorticoid influence on stress-related behavior and memory processes could underlie the depressogenic interaction of 5-HTTLPR and ELS. One possible mechanism could be the altered expression of the genes encoding the glucocorticoid and mineralocorticoid receptors (GR, MR) and their inhibitory regulator FK506-binding protein 51 (FKBP5) in stress-related forebrain areas. To test this notion, we exposed heterozygous (5-HTT^+/−) and homozygous (5-HTT^−/−) serotonin transporter knockout rats and their wildtype littermates (5-HTT^+/+) to daily 3 h maternal separations from postnatal day 2 to 14. In the medial prefrontal cortex (mPFC) and hippocampus of the adult male offspring, we found that GR, MR, and FKBP5 mRNA levels were affected by ELS × 5-HTT genotype interaction. Specifically, 5-HTT^+/+ rats exposed to ELS showed decreased GR and FKBP5 mRNA in the dorsal and ventral mPFC, respectively. In contrast, 5-HTT^+/− rats showed increased MR mRNA levels in the hippocampus and 5-HTT^−/− rats showed increased FKBP5 mRNA in the ventral mPFC after ELS exposure. These findings indicate that 5-HTT genotype determines the specific adaptation of GR, MR, and FKBP5 expression in response to early life adversity. Therefore, altered extra-hypothalamic glucocorticoid signaling should be considered to play a role in the depressogenic interaction of ELS and 5-HTTLPR.

The hypothalamic-pituitary-adrenal-leptin axis and metabolic health: a systems approach to resilience, robustness and control

Glucocorticoids contribute to obesity and metabolic syndrome; however, the mechanisms are unclear, and prognostic measures are unavailable. A systems level understanding of the hypothalamic-pituitary-adrenal (HPA)-leptin axis may reveal novel insights. Eighteen obese premenopausal women provided blood samples every 10 min over 24 h, which were assayed for cortisol, adrenocorticotropin releasing hormone (ACTH) and leptin. A published personalized HPA systems model was extended to incorporate leptin, yielding three parameters: (i) cortisol inhibitory feedback signalling, (ii) ACTH-adrenal signalling, and (iii) leptin-cortisol antagonism. We investigated associations between these parameters and metabolic risk profiles: fat and lean body mass (LBM; using dual-energy X-ray absorptiometry), and insulin resistance. Decreased cortisol inhibitory feedback signalling was significantly associated with greater fat (kg; p = 0.01) and insulin resistance (p = 0.03) but not LBM. Leptin significantly antagonized cortisol dynamics in eight women, who exhibited significantly lower 24 h mean leptin levels, LBM and higher ACTH-adrenal signalling nocturnally (all p < 0.05), compared with women without antagonism. Traditional neuroendocrine measures did not predict metabolic health, whereas a dynamic systems approach revealed that lower central inhibitory cortisol feedback signalling was significantly associated with greater metabolic risk. While exploratory, leptin-cortisol antagonism may reflect a 'neuroendocrine starvation' response.

Glucocorticoids promote neural progenitor cell proliferation derived from human induced pluripotent stem cells

Glucocorticoids (GCs) are frequently used for treating and preventing chronic lung disease and circulatory dysfunction in premature infants. However, there is growing concern about the detrimental effects of systemic GC administration on neurodevelopment. The first choice of GCs to minimize the adverse effects on the developing brain is still under debate. We investigated the effect of commonly used GCs such as dexamethasone (DEX), betamethasone (BET) and hydrocortisone (HDC) on the proliferation of human-induced pluripotent stem cell (iPSC)-derived neuronal progenitor cells (NPCs). In this study, NPCs were treated with various concentrations of GCs and subjected to cell proliferation assays. Furthermore, we quantified the number of microtubule-associated protein 2 (MAP2) positive neurons in NPCs by immunostaining. All GCs promoted NPC proliferation in a dose-dependent manner. We also confirmed that MAP2-positive neurons in NPCs increased upon GC treatment. However, differential effects of GCs on MAP2 positive neurons were observed when we treated NPCs with H₂O₂. The total numbers of NPCs increased upon any GC treatment even under oxidative conditions but the numbers of MAP2 positive neurons increased only by HDC treatment. GCs promoted human iPSCs–derived NPC proliferation and the differential effects of GCs became apparent under oxidative stress. Our results may support HDC as the preferred choice over DEX and BET to prevent adverse effects on the developing human brain.

Experience and the ever-changing brain: what the transcriptome can reveal

The brain is an ever-changing organ that encodes memories and directs behavior. Neuroanatomical studies have revealed structural plasticity of neural architecture, and advances in gene expression technology and epigenetics have demonstrated new mechanisms underlying the brain's dynamic nature. Stressful experiences challenge the plasticity of the brain, and prolonged exposure to environmental stress redefines the normative transcriptional profile of both neurons and glia, and can lead to the onset of mental illness. A more thorough understanding of normal and abnormal gene expression is needed to define the diseased brain and improve current treatments for psychiatric disorders. The efforts to describe gene expression networks have been bolstered by microarray and RNA-sequencing technologies. The heterogeneity of neural cell populations and their unique microenvironments, coupled with broad ranging interconnectivity, makes resolving this complexity exceedingly challenging and requires the combined efforts of single cell and systems level expression profiling to identify targets for therapeutic intervention.

Adrenal disorders and the paediatric brain: pathophysiological considerations and clinical implications

Various neurological and psychiatric manifestations have been recorded in children with adrenal disorders. Based on literature review and on personal case-studies and case-series we focused on the pathophysiological and clinical implications of glucocorticoid-related, mineralcorticoid-related, and catecholamine-related paediatric nervous system involvement. Childhood Cushing syndrome can be associated with long-lasting cognitive deficits and abnormal behaviour, even after resolution of the hypercortisolism. Exposure to excessive replacement of exogenous glucocorticoids in the paediatric age group (e.g., during treatments for adrenal insufficiency) has been reported with neurological and magnetic resonance imaging (MRI) abnormalities (e.g., delayed myelination and brain atrophy) due to potential corticosteroid-related myelin damage in the developing brain and the possible impairment of limbic system ontogenesis. Idiopathic intracranial hypertension (IIH), a disorder of unclear pathophysiology characterised by increased cerebrospinal fluid (CSF) pressure, has been described in children with hypercortisolism, adrenal insufficiency, and hyperaldosteronism, reflecting the potential underlying involvement of the adrenal-brain axis in the regulation of CSF pressure homeostasis. Arterial hypertension caused by paediatric adenomas or tumours of the adrenal cortex or medulla has been associated with various hypertension-related neurological manifestations. The development and maturation of the central nervous system (CNS) through childhood is tightly regulated by intrinsic, paracrine, endocrine, and external modulators, and perturbations in any of these factors, including those related to adrenal hormone imbalance, could result in consequences that affect the structure and function of the paediatric brain. Animal experiments and clinical studies demonstrated that the developing (i.e., paediatric) CNS seems to be particularly vulnerable to alterations induced by adrenal disorders and/or supraphysiological doses of corticosteroids. Physicians should be aware of potential neurological manifestations in children with adrenal dysfunction to achieve better prevention and timely diagnosis and treatment of these disorders. Further studies are needed to explore the potential neurological, cognitive, and psychiatric long-term consequences of high doses of prolonged corticosteroid administration in childhood.

Age-dependent effect of high cholesterol diets on anxiety-like behavior in elevated plus maze test in rats

Background

Cholesterol is an essential component of brain and nerve cells and is essential for maintaining the function of the nervous system. Epidemiological studies showed that patients suffering from anxiety disorders have higher serum cholesterol levels. In this study, we investigated the influence of high cholesterol diet on anxiety-like behavior in elevated plus maze in animal model and explored the relationship between cholesterol and anxiety-like behavior from the aspect of central neurochemical changes.

Methods

Young (3 weeks old) and adult (20 weeks old) rats were given a high cholesterol diet for 8 weeks. The anxiety-like behavior in elevated plus maze test and changes of central neurochemical implicated in anxiety were measured.

Results

In young rats, high cholesterol diet induced anxiolytic-like behavior, decreased serum corticosterone (CORT), increased hippocampal brain-derived neurotrophic factor (BDNF), increased hippocampal mineralocorticoid receptor (MR) and decreased glucocorticoid receptor (GR). In adult rats, high cholesterol diet induced anxiety-like behavior and increase of serum CORT and decrease of hippocampal BDNF comparing with their respective control group that fed the regular diet.

Discussion

High cholesterol diet induced age-dependent effects on anxiety-like behavior and central neurochemical changes. High cholesterol diet might affect the central nervous system (CNS) function differently, and resulting in different behavior performance of anxiety in different age period.

Stress physiology and developmental psychopathology: past, present, and future

Research on the hypothalamic-pituitary-adrenocortical (HPA) axis has emerged as a vital area within the field of developmental psychopathology in the past 25 years. Extensive animal research has provided knowledge of the substrates and physiological mechanisms that guide development of stress reactivity and regulation using methods that are not feasible in humans. Recent advances in understanding the anatomy and physiology of the HPA axis in humans and its interactions with other stress-mediating systems, including accurate assessment of salivary cortisol, more sophisticated neuroimaging methods, and a variety of genetic analyses, have led to greater knowledge of how psychological and biological processes impact functioning. A growing body of research on HPA axis regulation and reactivity in relation to psychopathology has drawn increased focus on the prenatal period, infancy, and the pubertal transition as potentially sensitive periods of stress system development in children. Theories such as the allostatic load model have guided research by integrating multiple physiological systems and mechanisms by which stress can affect mental and physical health. However, almost none of the prominent theoretical models in stress physiology are truly developmental, and future work must incorporate how systems interact with the environment across the life span in normal and atypical development. Our theoretical advancement will depend on our ability to integrate biological and psychological models. Researchers are increasingly realizing the importance of communication across disciplinary boundaries in order to understand how experiences influence neurobehavioral development. It is important that knowledge gained over the past 25 years has been translated to prevention and treatment interventions, and we look forward to the dissemination of interventions that promote recovery from adversity.

Neonatal handling: an overview of the positive and negative effects

As one of the first rodent models designed to investigate the effects of early-life experiences, the neonatal handling paradigm has helped us better understand how subtle changes in the infant environment can powerfully drive neurodevelopment of the immature brain in typical or atypical trajectories. Here, we review data from more than 50 years demonstrating the compelling effects of neonatal handling on behavior, physiology, and neural function across the lifespan. Moreover, we present data that challenge the classical view of neonatal handling as an animal model that results only in positive/beneficial outcomes. Indeed, the overall goal of this review is to offer the suggestion that the effects of early-life experiences-including neonatal handling-are nuanced rather than unidirectional. Both beneficial and negative outcomes may occur, depending on the parameters of testing, sex of the subject, and neurobehavioral system analyzed.

Glucocorticoid receptors in the retina, Müller glia and the formation of Müller glia-derived progenitors

Identification of the signaling pathways that influence the reprogramming of Müller glia into neurogenic retinal progenitors is key to harnessing the potential of these cells to regenerate the retina. Glucocorticoid receptor (GCR) signaling is commonly associated with anti-inflammatory responses and GCR agonists are widely used to treat inflammatory diseases of the eye, even though the cellular targets and mechanisms of action in the retina are not well understood. We find that signaling through GCR has a significant impact upon the ability of Müller glia to become proliferating Müller glia-derived progenitor cells (MGPCs). The primary amino acid sequence and pattern of GCR expression in the retina is highly conserved across vertebrate species, including chickens, mice, guinea pigs, dogs and humans. In all of these species we find GCR expressed by the Müller glia. In the chick retina, we find that GCR is expressed by progenitors in the circumferential marginal zone (CMZ) and is upregulated by Müller glia in acutely damaged retinas. Activation of GCR signaling inhibits the formation of MGPCs and antagonizes FGF2/MAPK signaling in the Müller glia. By contrast, we find that inhibition of GCR signaling stimulates the formation of proliferating MGPCs in damaged retinas, and enhances the neuronal differentiation while diminishing glial differentiation. Given the conserved expression pattern of GCR in different vertebrate retinas, we propose that the functions and mechanisms of GCR signaling are highly conserved and are mediated through the Müller glia. We conclude that GCR signaling directly inhibits the formation of MGPCs, at least in part, by interfering with FGF2/MAPK signaling.

Sex differences in stress-related psychiatric disorders: neurobiological perspectives

Stress is associated with the onset and severity of several psychiatric disorders that occur more frequently in women than men, including posttraumatic stress disorder (PTSD) and depression. Patients with these disorders present with dysregulation of several stress response systems, including the neuroendocrine response to stress, corticolimbic responses to negatively valenced stimuli, and hyperarousal. Thus, sex differences within their underlying circuitry may explain sex biases in disease prevalence. This review describes clinical studies that identify sex differences within the activity of these circuits, as well as preclinical studies that demonstrate cellular and molecular sex differences in stress responses systems. These studies reveal sex differences from the molecular to the systems level that increase endocrine, emotional, and arousal responses to stress in females. Exploring these sex differences is critical because this research can reveal the neurobiological underpinnings of vulnerability to stress-related psychiatric disorders and guide the development of novel pharmacotherapies.

Parallels between major depressive disorder and Alzheimer's disease: role of oxidative stress and genetic vulnerability

The thesis of this review is that oxidative stress is the central factor in major depressive disorder (MDD) and Alzheimer's disease (AD). The major elements involved are inflammatory cytokines, the hypothalamic-pituitary axis, the hypothalamic-pituitary gonadal, and arginine vasopressin systems, which induce glucocorticoid and "oxidopamatergic" cascades when triggered by psychosocial stress, severe life-threatening events, and mental-affective and somatic diseases. In individuals with a genomic vulnerability to depression, these cascades may result in chronic depression-anxiety-stress spectra, resulting in MDD and other known depressive syndromes. In contrast, in subjects with genomic vulnerability to AD, oxidative stress-induced brain damage triggers specific antioxidant defenses, i.e., increased levels of amyloid-β (Aβ) and aggregation of hyper-phosphorylated tau, resulting in paired helical filaments and impaired functions related to the ApoEε4 isoform, leading to complex pathological cascades culminating in AD. Surprisingly, all the AD-associated molecular pathways mentioned in this review have been shown to be similar or analogous to those found in depression, including structural damage, i.e., hippocampal and frontal cortex atrophy. Other interacting molecular signals, i.e., GSK-3β, convergent survival factors (brain-derived neurotrophic factor and heat shock proteins), and transition redox metals are also mentioned to emphasize the vast array of intermediates that could interact via comparable mechanisms in both MDD and AD.

Antidepressant-like effects of the ethyl acetate soluble fraction of the root bark of Morus alba on the immobility behavior of rats in the forced swim test

In this study, the antidepressant-like effects of Morus alba fractions in rats were investigated in the forced swim test (FST). Male Wistar rats (9-week-old) were administered orally the M. alba ethyl acetate (EtOAc 30 and 100 mg/kg) and M. alba n-butanol fractions (n-BuOH 30 and 100 mg/kg) every day for 7 consecutive days. On day 7, 1 h after the final administration of the fractions, the rats were exposed to the FST. M. alba EtOAc fraction at the dose of 100 mg/kg induced a decrease in immobility behavior (p < 0.01) with a concomitant increase in both climbing (p < 0.05) and swimming (p < 0.05) behaviors when compared with the control group, and M. alba EtOAc fraction at the dose of 100 mg/kg decreased the hypothalamic-pituitary-adrenal (HPA) axis response to the stress, as indicated by an attenuated corticosterone response and decreased c-fos immunoreactivity in the hippocampal and hypothalamic paraventricular nucleus (PVN) region. These findings demonstrated that M. alba EtOAc fraction have beneficial effects on depressive behaviors and restore both altered c-fos expression and HPA activity.

Maternal treatment with glucocorticoids modulates gap junction protein expression in the ovine fetal brain

Gap junctions facilitate intercellular communication and are important in brain development. Connexins (Cx) comprise a transmembrane protein family that forms gap junctions. Cx-32 is expressed in oligodendrocytes and neurons, Cx-36 in neurons, and Cx-43 in astrocytes. Although single antenatal steroid courses are recommended for fetal lung maturation, multiple courses can be given to women at recurrent risk for premature delivery. We examined the effects of single and multiple glucocorticoid courses on Cx-32, Cx-36, and Cx-43 protein expressions in the fetal cerebral cortex, cerebellum, and spinal cord, and differences in Cx expression among brain regions under basal conditions. In the single-course groups, the ewes received dexamethasone (6 mg) or placebo as four intramuscular injections every 12h over 48 h. In the multiple-course groups, the ewes received the same treatment, once a week for 5 weeks starting at 76-78 days of gestation. Cx were measured by Western immunoblot on brain samples from 105 to 108-day gestation fetuses. A single dexamethasone course was associated with increases (P<0.05) in cerebral cortical and spinal cord Cx-36 and Cx-43 and multiple courses with increases in cerebellar and spinal cord Cx-36, and cerebral cortical and cerebellar Cx-43. Cx-32 did not change. Cx-32 was higher in the cerebellum than cerebral cortex and spinal cord, Cx-36 higher in the spinal cord than cerebellum, and Cx-43 higher in the cerebellum and spinal cord than cerebral cortex during basal conditions. In conclusion, maternal glucocorticoid therapy increases specific Cx, responses to different maternal courses vary among Cx and brain regions, and Cx expression differs among brain regions under basal conditions. Maternal treatment with glucocorticoids differentially modulates Cx in the fetal brain.

Shifts in hormonal stress reactivity during adolescence are not associated with changes in glucocorticoid receptor levels in the brain and pituitary of male rats

Preadolescent animals display protracted hormonal stress responses mediated by the hypothalamic-pituitary-adrenal (HPA) axis compared to adults. Though the mechanisms that underlie this shift in stress reactivity are unknown, reduced glucocorticoid-dependent negative feedback on the HPA axis has been posited to contribute to this differential responsiveness. As the glucocorticoid receptors (GRs) are integral to this feedback response, we hypothesize that prior to puberty there will be fewer GRs in the neural-pituitary network that mediate negative feedback. To test this hypothesis we measured GR protein levels in the brains of preadolescent (28 days old), midadolescent (40 days old) and adult (77 days old) male rats via immunohistochemistry. Additionally, we assessed stress-induced plasma adrenocorticotropic hormone and corticosterone in prepubertal (30 days old) and adult (70 days old) male rats and examined GR protein levels via Western blot in the brain and pituitary. We found that despite substantial adolescent-related changes in hormonal responsiveness, no significant differences were found between these ages in GR protein levels in regions that are important in negative feedback, including the medial prefrontal cortex, paraventricular nucleus of the hypothalamus, hippocampal formation, and pituitary. These data indicate that the extended hormonal stress response exhibited by preadolescent animals is independent of significant pubertal changes in GR protein levels.

The different roles of glucocorticoids in the hippocampus and hypothalamus in chronic stress-induced HPA axis hyperactivity

Hypothalamus-pituitary-adrenal (HPA) hyperactivity is observed in many patients suffering from depression and the mechanism underling the dysfunction of HPA axis is not well understood. Chronic stress has a causal relationship with the hyperactivity of HPA axis. Stress induces the over-synthesis of glucocorticoids, which will arrive at all the body containing the brain. It is still complicated whether glucocorticoids account for chronic stress-induced HPA axis hyperactivity and in which part of the brain the glucocorticoids account for chronic stress-induced HPA axis hyperactivity. Here, we demonstrated that glucocorticoids were indispensable and sufficient for chronic stress-induced hyperactivity of HPA axis. Although acute glucocorticoids elevation in the hippocampus and hypothalamus exerted a negative regulation of HPA axis, we found that chronic glucocorticoids elevation in the hippocampus but not in the hypothalamus accounted for chronic stress-induced hyperactivity of HPA axis. Chronic glucocorticoids exposure in the hypothalamus still exerted a negative regulation of HPA axis activity. More importantly, we found mineralocorticoid receptor (MR) - neuronal nitric oxide synthesis enzyme (nNOS) - nitric oxide (NO) pathway mediated the different roles of glucocorticoids in the hippocampus and hypothalamus in regulating HPA axis activity. This study suggests that the glucocorticoids in the hippocampus play an important role in the development of HPA axis hyperactivity and the glucocorticoids in the hypothalamus can't induce hyperactivity of HPA axis, revealing new insights into understanding the mechanism of depression.

Association between postnatal dexamethasone for treatment of bronchopulmonary dysplasia and brain volumes at adolescence in infants born very preterm

OBJECTIVES

To compare brain volumes in adolescents who were born extremely preterm (<28 weeks gestation) who had received postnatal dexamethasone, and to determine if there was a postnatal dexamethasone dose-response effect on brain volumes.

STUDY DESIGN

Geographical cohort study of extremely preterm adolescents born in 1991-1992 in Victoria, Australia. T1-weighted magnetic resonance imaging was performed at 18 years of age. Segmented and parcellated brain volumes were calculated using an automated segmentation method (FreeSurfer) and compared between groups, with and without adjustment for potential confounders. The relationships between total postnatal dexamethasone dose and brain volumes were explored using linear regression.

RESULTS

Of the 148 extremely preterm participants, 55 (37%) had received postnatal dexamethasone, with a cumulative mean dose of 7.7 mg/kg. Compared with participants who did not receive postnatal dexamethasone, those who did had smaller total brain tissue volumes (mean difference -3.6%, 95% CI [-7.0%, -0.3%], P value = .04) and smaller white matter, thalami, and basal ganglia volumes (all P < .05). There was a trend of smaller total brain and white matter volumes with increasing dose of postnatal dexamethasone (regression coefficient -7.7 [95% CI -16.2, 0.8] and -3.2 [-6.6, 0.2], respectively).

CONCLUSIONS

Extremely preterm adolescents who received postnatal dexamethasone in the newborn period had smaller total brain tissue volumes than those who did not receive postnatal dexamethasone, particularly white matter, thalami, and basal ganglia. Vulnerability of brain tissues or structures associated with postnatal dexamethasone varies by structure and persists into adolescence.

Glucocorticoid actions on synapses, circuits, and behavior: implications for the energetics of stress

Environmental stimuli that signal real or potential threats to homeostasis lead to glucocorticoid secretion by the hypothalamic-pituitary-adrenocortical (HPA) axis. Glucocorticoids promote energy redistribution and are critical for survival and adaptation. This adaptation requires the integration of multiple systems and engages key limbic-neuroendocrine circuits. Consequently, glucocorticoids have profound effects on synaptic physiology, circuit regulation of stress responsiveness, and, ultimately, behavior. While glucocorticoids initiate adaptive processes that generate energy for coping, prolonged or inappropriate glucocorticoid secretion becomes deleterious. Inappropriate processing of stressful information may lead to energetic drive that does not match environmental demand, resulting in risk factors for pathology. Thus, dysregulation of the HPA axis may promote stress-related illnesses (e.g. depression, PTSD). This review summarizes the latest developments in central glucocorticoid actions on synaptic, neuroendocrine, and behavioral regulation. Additionally, these findings will be discussed in terms of the energetic integration of stress and the importance of context-specific regulation of glucocorticoids.

The HPA - Immune Axis and the Immunomodulatory Actions of Glucocorticoids in the Brain

In response to physiological and psychogenic stressors, the hypothalamic–pituitary–adrenal (HPA) axis orchestrates the systemic release of glucocorticoids (GCs). By virtue of nearly ubiquitous expression of the GC receptor and the multifaceted metabolic, cardiovascular, cognitive, and immunologic functions of GCs, this system plays an essential role in the response to stress and restoration of an homeostatic state. GCs act on almost all types of immune cells and were long recognized to perform salient immunosuppressive and anti-inflammatory functions through various genomic and non-genomic mechanisms. These renowned effects of the steroid hormone have been exploited in the clinic for the past 70 years and synthetic GC derivatives are commonly used for the therapy of various allergic, autoimmune, inflammatory, and hematological disorders. The role of the HPA axis and GCs in restraining immune responses across the organism is however still debated in light of accumulating evidence suggesting that GCs can also have both permissive and stimulatory effects on the immune system under specific conditions. Such paradoxical actions of GCs are particularly evident in the brain, where substantial data support either a beneficial or detrimental role of the steroid hormone. In this review, we examine the roles of GCs on the innate immune system with a particular focus on the CNS compartment. We also dissect the numerous molecular mechanisms through which GCs exert their effects and discuss the various parameters influencing the paradoxical immunomodulatory functions of GCs in the brain.

Evidence for adverse effect of perinatal glucocorticoid use on the developing brain

The use of glucocorticoids (GCs) in the perinatal period is suspected of being associated with adverse effects on long-term neurodevelopmental outcomes for preterm infants. Repeated administration of antenatal GCs to mothers at risk of preterm birth may adversely affect fetal growth and head circumference. Fetal exposure to excess GCs during critical periods of brain development may profoundly modify the limbic system (primarily the hippocampus), resulting in long-term effects on cognition, behavior, memory, co-ordination of the autonomic nervous system, and regulation of the endocrine system later in adult life. Postnatal GC treatment for chronic lung disease in premature infants, particularly involving the use of dexamethasone, has been shown to induce neurodevelopmental impairment and increases the risk of cerebral palsy. In contrast to studies involving postnatal dexamethasone, long-term follow-up studies for hydrocortisone therapy have not revealed adverse effects on neurodevelopmental outcomes. In experimental studies on animals, GCs has been shown to impair neurogenesis, and induce neuronal apoptosis in the immature brains of newborn animals. A recent study has demonstrated that dexamethasone-induced hypomyelination may result from the apoptotic degeneration of oligodendrocyte progenitors in the immature brain. Thus, based on clinical and experimental studies, there is enough evidence to advice caution regarding the use of GCs in the perinatal period; and moreover, the potential long-term effects of GCs on brain development need to be determined.

Influence of stress-induced intermediates on gonadotropin gene expression in gonadotrope cells

Despite extensive investigation, a comprehensive understanding of the mechanisms whereby stress impacts fertility remains elusive. Since the 1930s, when Hans Selye popularized studying adaptations to stress (Selye, 1937), we have learned that compensatory mechanisms involve a complex interplay of neural and hormonal processes that allow various body functions to adjust to stress, in a coordinated manner. In terms of reproduction, the adjustment to a stressor interferes with integrated functioning at multiple levels of regulation--the hypothalamus, anterior pituitary gland, gonads, and neural centers coordinating behavior. Various mediators are postulated to participate in reproductive suppression. These include catecholamines, cytokines, prostaglandins, endogenous opioid peptides, and hormones of the hypothalamic-pituitary-adrenal axis. This review focuses on one class of mediators, the glucocorticoids, and provides our views on the relevance and mode of action of this inhibitory intermediate within the anterior pituitary gonadotrope, as a potential cellular site whereby glucocorticoids contribute to stress-induced reproductive suppression.

Effects of selective and non-selective glucocorticoid receptor II antagonists on rapid-onset diabetes in young rats

The blockade of glucocorticoid (GC) action through antagonism of the glucocorticoid receptor II (GRII) has been used to minimize the undesirable effects of chronically elevated GC levels. Mifepristone (RU486) is known to competitively block GRII action, but not exclusively, as it antagonizes the progesterone receptor. A number of new selective GRII antagonists have been developed, but limited testing has been completed in animal models of overt type 2 diabetes mellitus. Therefore, two selective GRII antagonists (C113176 and C108297) were tested to determine their effects in our model of GC-induced rapid-onset diabetes (ROD). Male Sprague-Dawley rats (∼ six weeks of age) were placed on a high-fat diet (60%), surgically implanted with pellets containing corticosterone (CORT) or wax (control) and divided into five treatment groups. Each group was treated with either a GRII antagonist or vehicle for 14 days after surgery: CORT pellets (400 mg/rat) + antagonists (80 mg/kg/day); CORT pellets + drug vehicle; and wax pellets (control) + drug vehicle. After 10 days of CORT treatment, body mass gain was increased with RU486 (by ∼20% from baseline) and maintained with C113176 administration, whereas rats given C108297 had similar body mass loss (∼15%) to ROD animals. Fasting glycemia was elevated in the ROD animals (>20 mM), normalized completely in animals treated with RU486 (6.2±0.1 mM, p<0.05) and improved in animals treated with C108297 and C113176 (14.0±1.6 and 8.8±1.6 mM, p<0.05 respectively). Glucose intolerance was normalized with RU486 treatment, whereas acute insulin response was improved with RU486 and C113176 treatment. Also, peripheral insulin resistance was attenuated with C113176 treatment along with improved levels of β-cell function while C108297 antagonism only provided modest improvements. In summary, C113176 is an effective agent that minimized some GC-induced detrimental metabolic effects and may provide an alternative to the effective, but non-selective, GRII antagonist RU486.

Hippocampal corticosterone impairs memory consolidation during sleep but improves consolidation in the wake state

We studied the interaction between glucocorticoid (GC) level and sleep/wake state during memory consolidation. Recent research has accumulated evidence that sleep supports memory consolidation in a unique physiological process, qualitatively distinct from consolidation occurring during wakefulness. This appears particularly true for memories that rely on the hippocampus, a region with abundant expression of GC receptors. Against this backdrop we hypothesized that GC effects on consolidation depend on the brain state, i.e., sleep and wakefulness. Following exploration of two objects in an open field, during 80 min retention periods rats received an intrahippocampal infusion of corticosterone (10 ng) or vehicle while asleep or awake. Then the memory was tested in the hippocampus-dependent object-place recognition paradigm. GCs impaired memory consolidation when administered during sleep but improved consolidation during the wake retention interval. Intrahippocampal infusion of GC or sleep/wake manipulations did not alter novel-object recognition performance that does not require the hippocampus. This work corroborates the notion of distinct consolidation processes occurring in sleep and wakefulnesss, and identifies GCs as a key player controlling distinct hippocampal memory consolidation processes in sleep and wake conditions.

Molecular patterns of neurodevelopmental preconditioning: a study of the effects of antenatal steroid therapy in a protein-restriction mouse model

Introduction. Prenatal programming secondary to maternal protein restriction renders an inherent susceptibility to neural compromise in neonates and any addition of glucocorticosteroids results in further damage. This is an investigation of consequent global gene activity due to effects of antenatal steroid therapy on a protein restriction mouse model. Methods. C57BL/6N pregnant mice were administered control or protein restricted diets and subjected to either 100 μg/Kg of dexamethasone sodium phosphate with normosaline or normosaline alone during late gestation (E10–E17). Nontreatment groups were also included. Brain samples were collected on embryonic day 17 and analyzed by mRNA microarray analysis. Results. Microarray analyses presented 332 significantly regulated genes. Overall, neurodevelopmental genes were overrepresented and a subset of 8 genes allowed treatment segregation through the hierarchical clustering method. The addition of stress or steroids greatly affected gene regulation through glucocorticoid receptor and stress signaling pathways. Furthermore, differences between dexamethasone-administered treatments implied a harmful effect during conditions of high stress. Microarray analysis was validated using qPCR. Conclusion. The effects of antenatal steroid therapy vary in fetuses according to maternal-fetal factors and environmental stimuli. Defining the key regulatory networks that signal either beneficial or damaging corticosteroid action would result in valuable adjustments to current treatment protocols.

Steroids and injury to the developing brain: net harm or net benefit?

Deleterious effects result from both glucocorticoid insufficiency and excess glucocorticoid tissue exposure in the developing brain. Accumulating evidence suggests a net benefit of postnatal glucocorticoid therapy when administered shortly after the first week of life to premature infants with early and persistent pulmonary dysfunction, particularly in those with evidence of relative adrenal insufficiency. The decision to treat with steroids should ensure maximum respiratory benefit at the lowest possible neurologic risk, while avoiding serious systemic complications. Ongoing clinical trials must validate this approach.

Regulation of 11β-hydroxysteroid dehydrogenase type 1 and 7α-hydroxylase CYP7B1 during social stress

11β-hydroxysteroid dehydrogenase type 1 (11HSD1) is an enzyme that amplifies intracellular glucocorticoid concentration by the conversion of inert glucocorticoids to active forms and is involved in the interconversion of 7-oxo- and 7-hydroxy-steroids, which can interfere with the activation of glucocorticoids. The presence of 11HSD1 in the structures of the hypothalamic-pituitary-adrenal (HPA) axis suggests that this enzyme might play a role in the regulation of HPA output. Here we show that the exposure of Fisher 344 rats to mild social stress based on the resident-intruder paradigm increased the expression of 11HSD1 and CYP7B1, an enzyme that catalyzes 7-hydroxylation of steroids. We found that social behavioral profile of intruders was significantly decreased whereas their plasma levels of corticosterone were increased more than in residents. The stress did not modulate 11HSD1 in the HPA axis (paraventricular nucleus, pituitary, adrenal cortex) but selectively upregulated 11HSD1 in some regions of the hippocampus, amygdala and prelimbic cortex. In contrast, CYP7B1 was upregulated not only in the hippocampus and amygdala but also in paraventricular nucleus and pituitary. Furthermore, the stress downregulated 11HSD1 in the thymus and upregulated it in the spleen and mesenteric lymphatic nodes whereas CYP7B1 was upregulated in all of these lymphoid organs. The response of 11HSD1 to stress was more obvious in intruders than in residents and the response of CYP7B1 to stress predominated in residents. We conclude that social stress induces changes in enzymes of local metabolism of glucocorticoids in lymphoid organs and in brain structures associated with the regulation of the HPA axis. In addition, the presented data clearly suggest a role of 11HSD1 in modulation of glucocorticoid feedback of the HPA axis during stress.

Stress, glucocorticoid receptors, and adult neurogenesis: a balance between excitation and inhibition?

Adult neurogenesis, the birth of new neurons in the mature brain, has attracted considerable attention in the last decade. One of the earliest identified and most profound factors that affect adult neurogenesis both positively and negatively is stress. Here, we review the complex interplay between stress and adult neurogenesis. In particular, we review the role of the glucocorticoid receptor, the main mediator of the stress response in the proliferation, differentiation, migration, and functional integration of newborn neurons in the hippocampus. We review a multitude of mechanisms regulating glucocorticoid receptor activity in relationship to adult neurogenesis. We postulate a novel concept in which the level of glucocorticoid receptor expression directly regulates the excitation-inhibition balance, which is key for proper neurogenesis. We furthermore argue that an excitation-inhibition dis-balance may underlie aberrant functional integration of newborn neurons that is associated with psychiatric and paroxysmal brain disorders.

Deletion of the forebrain mineralocorticoid receptor impairs social discrimination and decision-making in male, but not in female mice

Social interaction with unknown individuals requires fast processing of information to decide whether it is friend or foe. This process of discrimination and decision-making is stressful and triggers secretion of corticosterone activating mineralocorticoid receptor (MR) and glucocorticoid receptor (GR). The MR is involved in appraisal of novel experiences and risk assessment. Recently, we have demonstrated in a dual-solution memory task that MR plays a role in the early stage of information processing and decision-making. Here we examined social approach and social discrimination in male and female mice lacking MR from hippocampal-amygdala-prefrontal circuitry and controls. The social approach task allows the assessment of time spent with an unfamiliar mouse and the ability to discriminate between familiar and unfamiliar conspecifics. The male and female test mice were both more interested in the social than the non-social experience and deletion of their limbic MR increased the time spent with an unfamiliar mouse. Unlike controls, the male MR^CaMKCre mice were not able to discriminate between an unfamiliar and the familiar mouse. However, the female MR mutant had retained the discriminative ability between unfamiliar and familiar mice. Administration of the MR antagonist RU28318 to male mice supported the role of the MR in the discrimination between an unfamiliar mouse and a non-social stimulus. No effect was found with a GR antagonist. Our findings suggest that MR is involved in sociability and social discrimination in a sex-specific manner through inhibitory control exerted putatively via limbic-hippocampal efferents. The ability to discriminate between familiar and unfamiliar conspecifics is of uttermost importance for territorial defense and depends on a role of MR in decision-making.

Vaginal hypersensitivity and hypothalamic-pituitary-adrenal axis dysfunction as a result of neonatal maternal separation in female mice

Early life stress can permanently alter functioning of the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the stress response and influences the perception of pain. Chronic pelvic pain patients commonly report having experienced childhood neglect or abuse, which increases the likelihood of presenting with comorbid chronic pain and/or mood disorders. Animal models of neonatal stress commonly display enhanced anxiety-like behaviors, colorectal hypersensitivity, and disruption of proper neuro-immune interactions in adulthood. Here, we tested the hypothesis that early life stress impacts vaginal sensitivity by exposing mice to neonatal maternal separation (NMS) for 3h/day during the first two (NMS14) or three (NMS21) postnatal weeks. As adults, female mice underwent vaginal balloon distension (VBD), which was also considered an acute stress. Before or after VBD, mice were assessed for anxiety-like behavior, hindpaw sensitivity, and changes in gene and protein expression related to HPA axis function and regulation. NMS21 mice displayed significantly increased vaginal sensitivity compared to naïve mice, as well as significantly reduced anxiety-like behavior at baseline, which was heightened following VBD. NMS21 mice exhibited significant thermal and mechanical hindpaw hypersensitivity at baseline and following VBD. NMS14 mice displayed no change in anxiety-like behavior and only exhibited significantly increased hindpaw mechanical and thermal sensitivity following VBD. Centrally, a significant decrease in negative regulation of the HPA axis was observed in the hypothalamus and hippocampus of NMS21 mice. Peripherally, NMS and VBD affected the expression of inflammatory mediators in the vagina and bladder. Corticotropin-releasing factor (CRF) receptor and transient receptor potential (TRP) channel protein expression was also significantly, and differentially, affected in vagina, bladder, and colon by both NMS and VBD. Together these data indicate that NMS affects both central and peripheral aspects of the HPA axis, which may drive changes in vaginal sensitivity and the development of comorbid chronic pain and mood disorders.

Distinct effect of stress on 11beta-hydroxysteroid dehydrogenase type 1 and corticosteroid receptors in dorsal and ventral hippocampus

Multiple lines of evidence suggest the participation of the hippocampus in the feedback inhibition of the hypothalamus-pituitary-adrenal axis during stress response. This inhibition is mediated by glucocorticoid feedback due to the sensitivity of the hippocampus to these hormones. The sensitivity is determined by the expression of glucocorticoid (GR) and mineralocorticoid (MR) receptors and 11beta-hydroxysteroid dehydrogenase type 1 (11HSD1), an enzyme that regulates the conversion of glucocorticoids from inactive to active form. The goal of our study was to assess the effect of stress on the expression of 11HSD1, GR and MR in the ventral and dorsal region of the CA1 hippocampus in three different rat strains with diverse responses to stress: Fisher 344, Lewis and Wistar. Stress stimulated 11HSD1 in the ventral but not dorsal CA1 hippocampus of Fisher 344 but not Lewis or Wistar rats. In contrast, GR expression following stress was decreased in the dorsal but not ventral CA1 hippocampus of all three strains. MR expression was not changed in either the dorsal or ventral CA1 region. These results indicate that (1) depending on the strain, stress stimulates 11HSD1 in the ventral hippocampus, which is known to be involved in stress and emotion reactions whereas (2) independent of strain, stress inhibits GR in the dorsal hippocampus, which is predominantly involved in cognitive functions.

Novel insights into the neuroendocrine control of inflammation: the role of GR and PARP1

Inflammatory responses are elicited after injury, involving release of inflammatory mediators that ultimately lead, at the molecular level, to the activation of specific transcription factors (TFs; mainly activator protein 1 and nuclear factor-κB). These TFs propagate inflammation by inducing the expression of cytokines and chemokines. The neuroendocrine system has a determinant role in the maintenance of homeostasis, to avoid exacerbated inflammatory responses. Glucocorticoids (GCs) are the key neuroendocrine regulators of the inflammatory response. In this study, we describe the molecular mechanisms involved in the interplay between inflammatory cytokines, the neuroendocrine axis and GCs necessary for the control of inflammation. Targeting and modulation of the glucocorticoid receptor (GR) and its activity is a common therapeutic strategy to reduce pathological signaling. Poly (ADP-ribose) polymerase 1 (PARP1) is an enzyme that catalyzes the addition of PAR on target proteins, a post-translational modification termed PARylation. PARP1 has a central role in transcriptional regulation of inflammatory mediators, both in neuroendocrine tumors and in CNS cells. It is also involved in modulation of several nuclear receptors. Therefore, PARP1 and GR share common inflammatory pathways with antagonic roles in the control of inflammatory processes, which are crucial for the effective maintenance of homeostasis.

Early Life Stress in Depressive Patients: HPA Axis Response to GR and MR Agonist

BACKGROUND

Evidence indicates that early life stress (ELS) can induce persistent changes in the hypothalamic-pituitary-adrenal (HPA) axis to respond to stress in the adult life that leads to depression. These appear to be related to the impairment of HPA hormones through binding to glucocorticoid (GR) and mineralocorticoid receptors (MR). The aim of this study was to evaluate the impact of ELS in HPA axis response to challenges with GR and MR agonists in depressed patients.

METHODS

We included 30 subjects, 20 patients with current major depression (HAM-D21 ≥ 17). Patients were recruited into two groups according to ELS history assessed by the Childhood Trauma Questionnaire (CTQ). The cortisol measures in the saliva and plasma were evaluated after using (at 10:00 p.m.) placebo, fludrocortisone (MR agonist), or dexamethasone (GR agonist).

RESULTS

Depressed patients showed a significantly lower salivary cortisol upon waking after placebo compared with controls. Moreover, cortisol awakening responses (CAR) after MR agonist were found to be lower in depressed patients than in controls. With CTQ scores, HAM-D21, body mass index and CAR after placebo, GR agonist, MR agonist we found in a Linear Regression model that depressive patients with ELS (p = 0.028) show differences between placebo vs. MR agonist (R = 0.51; p < 0.05) but not after GR agonist; in depressive patients, without ELS the data show differences between placebo vs. MR agonist (R = 0.69; p < 0.05); but now as well placebo vs. GR agonist (R = 0.53; p < 0.05).

CONCLUSION

Our findings indicate that MR activity is impaired in depressed patients compared with controls. Furthermore, in spite of the previous limitations described, in depressed patients with ELS, there was suppression by MR agonist, indicating that patients with ELS are sensitive to MR agonists. In contrast with depressed patients without ELS, we find suppression after both MR and GR agonist. These data suggested that in ELS an imbalance exists between MR and GR with MR dysfunction.

Nonhuman primate models of depression: effects of early experience and stress

Depression causes significant morbidity in the human population. The Diathesis-Stress/Two-Hit model of depression hypothesizes that stress interacts with underlying (probably genetic) predispositions to produce a central nervous system that is primed to express psychopathology when confronted with stressful experiences later in life. Nonhuman primate (NHP) studies have been extensively utilized to test this model. NHPs are especially useful for studying effects of early experience, because many aspects of NHP infancy are similar to humans, whereas development occurs at an accelerated rate and therefore allows for more rapid assessment of experimental variables. In addition, the ability to manipulate putative risk factors, including introducing experimental stress during development, allows inference of causality not possible with human studies. This manuscript reviews experimental paradigms that have been utilized to model early adverse experience in NHPs, including peer-rearing, maternal separation, and variable foraging. It also provides examples of how this model has been used to investigate the effects of early experience on later neurobiology, physiology, and behavior associated with depression. We conclude that the NHP offers an excellent model to research mechanisms contributing to the Diathesis-Stress/Two-Hit model of depression.

Disruption of fetal hormonal programming (prenatal stress) implicates shared risk for sex differences in depression and cardiovascular disease

Comorbidity of major depressive disorder (MDD) and cardiovascular disease (CVD) represents the fourth leading cause of morbidity and mortality worldwide, and women have a two times greater risk than men. Thus understanding the pathophysiology has widespread implications for attenuation and prevention of disease burden. We suggest that sex-dependent MDD-CVD comorbidity may result from alterations in fetal programming consequent to the prenatal maternal environments that produce excess glucocorticoids, which then drive sex-dependent developmental alterations of the fetal hypothalamic-pituitary-adrenal (HPA) axis circuitry impacting mood, stress regulation, autonomic nervous system (ANS), and the vasculature in adulthood. Evidence is consistent with the hypothesis that disruptions of pathways associated with gamma aminobutyric acid (GABA) in neuronal and vascular development and growth factors have critical roles in key developmental periods and adult responses to injury in heart and brain. Understanding the potential fetal origins of these sex differences will contribute to development of novel sex-dependent therapeutics.

Mechanisms underlying the increased plasma ACTH levels in chronic psychosocially stressed male mice

Mice exposed to chronic subordinate colony housing (CSC, 19 days), an established paradigm for chronic psychosocial stress, show unaffected basal morning plasma corticosterone (CORT) concentrations, despite enlarged adrenal glands and an increased CORT response to an acute heterotypic stressor. In the present study we investigate the mechanisms underlying these phenomena at the level of the pituitary. We show that both basal and acute stressor-induced (forced swim (FS), 6 min) plasma adrenocorticotropic hormone (ACTH) concentrations, the number of total and corticotroph pituitary cells, and relative protein expression of pituitary mineralocorticoid receptor and FK506-binding protein 51 was increased in CSC compared with single-housed control (SHC) mice, while relative corticotropin releasing hormone (CRH) receptor 1 (CRH-R1) and glucocorticoid receptor protein expression was down-regulated. Relative pituitary pro-opiomelanocortin and arginine vasopressin (AVP) receptor 1b (AVPR-1b) protein expression, FS (6 min)-induced ACTH secretion in dexamethasone-blocked mice, and the number of AVP positive magnocellular and parvocellular neurons in the paraventricular hypothalamic nucleus (PVN) was unaffected following CSC. Taken together, the data of the present study indicate that 19 days of CSC result in pituitary hyperactivity, under both basal and acute heterotypic stress conditions. Although further studies have to assess this in detail, an increased number of pituitary corticotrophs together with unaffected relative pituitary AVPR-1b and decreased CRH-R1 protein expression following CSC suggests that pituitary hyperdrive is mediated by newly formed corticotrophs that are more sensitive to AVP than CRH. Moreover, our data indicate that changes in PVN AVP and negative feedback inhibition seem not to play a major role in pituitary hyperactivity following CSC.