Signaling pathways in brain involved in predisposition and pathogenesis of stress-related disease: genetic and kinetic factors affecting the MR/GR balance

Resveratrol: A Multifaceted Guardian against Anxiety and Stress Disorders-An Overview of Experimental Evidence

The medicinal properties of resveratrol have garnered increasing attention from researchers. Extensive data have been accumulated on its use in treating cardiovascular diseases, immune system disorders, cancer, neurological diseases, and behavioral disorders. The protective mechanisms of resveratrol, particularly in anxiety-related stress disorders, have been well documented. However, less attention has been given to the side effects of resveratrol. This review explores not only the mechanisms underlying the anxiolytic effects of resveratrol but also the mechanisms that may lead to increased anxiety following resveratrol treatment. Understanding these mechanisms is crucial for enhancing the efficacy of resveratrol in managing anxiety disorders associated with stress and PTSD.

Exploratory Review of the Takotsubo Syndrome and the Possible Role of the Psychosocial Stress Response and Inflammaging

Takotsubo syndrome (TTS) is a cardiomyopathy that clinically presents as a transient and reversible left ventricular wall motion abnormality (LVWMA). Recovery can occur spontaneously within hours or weeks. Studies have shown that it mainly affects older people. In particular, there is a higher prevalence in postmenopausal women. Physical and emotional stress factors are widely discussed and generally recognized triggers. In addition, the hypothalamic-pituitary-adrenal (HPA) axis and the associated glucocorticoid-dependent negative feedback play an important role in the resulting immune response. This review aims to highlight the unstudied aspects of the trigger factors of TTS. The focus is on emotional stress/chronic unpredictable mild stress (CUMS), which is influenced by estrogen concentration and noradrenaline, for example, and can lead to changes in the behavioral, hormonal, and autonomic systems. Age- and gender-specific aspects, as well as psychological effects, must also be considered. We hypothesize that this leads to a stronger corticosteroid response and altered feedback of the HPA axis. This may trigger proinflammatory markers and thus immunosuppression, inflammaging, and sympathetic overactivation, which contributes significantly to the development of TTS. The aim is to highlight the importance of CUMS and psychological triggers as risk factors and to make an exploratory proposal based on the new knowledge. Based on the imbalance between the sympathetic and parasympathetic nervous systems, transcutaneous vagus nerve stimulation (tVNS) is presented as a possible new therapeutic approach.

Neurosteroids (allopregnanolone) and alcohol use disorder: From mechanisms to potential pharmacotherapy

Alcohol Use Disorder (AUD) is a multifaceted relapsing disorder that is commonly comorbid with psychiatric disorders, including anxiety. Alcohol exposure produces a plethora of effects on neurobiology. Currently, therapeutic strategies are limited, and only a few treatments - disulfiram, acamprosate, and naltrexone - are available. Given the complexity of this disorder, there is a great need for the identification of novel targets to develop new pharmacotherapy. The GABAergic system, the primary inhibitory system in the brain, is one of the well-known targets for alcohol and is responsible for the anxiolytic effects of alcohol. Interestingly, GABAergic neurotransmission is fine-tuned by neuroactive steroids that exert a regulatory role on several endocrine systems involved in neuropsychiatric disorders including AUD. Mounting evidence indicates that alcohol alters the biosynthesis of neurosteroids, whereas acute alcohol increases and chronic alcohol decreases allopregnanolone levels. Our recent work highlighted that chronic alcohol-induced changes in neurosteroid levels are mediated by epigenetic modifications, e.g., DNA methylation, affecting key enzymes involved in neurosteroid biosynthesis. These changes were associated with changes in GABAA receptor subunit expression, suggesting an imbalance between excitatory and inhibitory signaling in AUD. This review will recapitulate the role of neurosteroids in the regulation of the neuroendocrine system, highlight their role in the observed allostatic load in AUD, and develop a framework from mechanisms to potential pharmacotherapy.

Integrative Brain Dynamics in Childhood Bullying Victimization: Cognitive and Emotional Convergence Associated With Stress Psychopathology

Bullying victimization is a form of psychological stress that is associated with poor outcomes in the areas of mental health and learning. Although the emotional maladjustment and memory impairment following interpersonal stress are well documented, the mechanisms of complex cerebral dysfunctions have neither been outlined nor studied in depth in the context of childhood bullying victimization. As a contribution to the cross-disciplinary field of developmental psychology and neuroscience, we review the neuropathophysiology of early life stress, as well as general psychological stress to synthesize the data and clarify the versatile dynamics within neuronal networks linked to bullying victimization. The stress-induced neuropsychological cascade and associated cerebral networks with a focus on cognitive and emotional convergence are described. The main findings are that stress-evoked neuroendocrine reactivity relates to neuromodulation and limbic dysregulation that hinder emotion processing and executive functioning such as semantic cognition, cognitive flexibility, and learning. Developmental aspects and interacting neural mechanisms linked to distressed cognitive and emotional processing are pinpointed and potential theory-of-mind nuances in targets of bullying are presented. The results show that childhood stress psychopathology is associated with a complex interplay where the major role belongs to, but is not limited to, the amygdala, fusiform gyrus, insula, striatum, and prefrontal cortex. This interplay contributes to the sensitivity toward facial expressions, poor cognitive reasoning, and distress that affect behavioral modulation and emotion regulation. We integrate the data on major brain dynamics in stress neuroactivity that can be associated with childhood psychopathology to help inform future studies that are focused on the treatment and prevention of psychiatric disorders and learning problems in bullied children and adolescents.

Effects of semi-purified diet on depressive behaviors in aged mice

Diet is a key modifiable factor influencing the composition of gut microbiota. There are two types of commercially available diets for experimental animals: non-purified and semi-purified diets. Non-purified diets are composed of complex ingredients from multiple sources, while semi-purified diets are formulated with refined ingredients. Accumulating evidence has demonstrated a link between the gut microbiota and depression, and feed ingredients may influence depressive physiology and behaviors. To test this hypothesis, we examined how chronic non-purified (CRF-1) and semi-purified (AIN-93G) diets affected phenotypes, including depressive behaviors, plasma corticosterone levels, and small-intestine microbiota in young (2 months old) and aged (22 months old) inbred C57BL/JJcl mice. In young mice, similar phenotypes were associated with non-purified and semi-purified diets. However, in aged mice, semi-purified diets increased depressive behaviors in the tail suspension (P < 0.05) and forced swimming tests (P < 0.01). The corticosterone levels were similar between the two diets under normal rearing conditions. However, immediately after exposure to the stressful conditions of the forced swimming test, the corticosterone levels in the aged mice fed the semi-purified diet were higher than those of mice fed the non-purified diet (P < 0.05). There were fewer Lactobacillales in the small intestines of aged mice fed the semi-purified diet compared to those fed the non-purified diet (P < 0.01). Further, α-diversity was lower in aged mice fed the semi-purified versus non-purified diet (P < 0.01). Our results indicate that host physiology and gut microbiota differed according to whether the aged mice were fed a non-purified or semi-purified diet. Specifically, those fed the semi-purified diet were more vulnerable to stress than age-matched mice fed the non-purified diet. Our findings indicate that researchers should consider the effects of feed ingredients on depressive physiology and behaviors, and select diets that are appropriate for their particular research design. Further, identification of the ingredients in non-purified diets could facilitate examination of the mechanisms by which gut microbiota composition might increase resistance to stress and depression.

Norepinephrine and Glucocorticoids Modulate Chronic Unpredictable Stress-Induced Increase in the Type 2 CRF and Glucocorticoid Receptors in Brain Structures Related to the HPA Axis Activation

The stress response is multifactorial and enrolls circuitries to build a coordinated reaction, leading to behavioral, endocrine, and autonomic changes. These changes are mainly related to the hypothalamus-pituitary-adrenal (HPA) axis activation and the organism's integrity. However, when self-regulation is ineffective, stress becomes harmful and predisposes the organism to pathologies. The chronic unpredictable stress (CUS) is a widely used experimental model since it induces physiological and behavioral changes and better mimics the stressors variability encountered in daily life. Corticotropin-releasing factor (CRF) and glucocorticoids (GCs) are deeply implicated in the CUS-induced physiological and behavioral changes. Nonetheless, the CUS modulation of CRF receptors and GR and the norepinephrine role in extra-hypothalamic brain areas were not well explored. Here, we show that 14 days of CUS induced a long-lasting HPA axis hyperactivity evidenced by plasmatic corticosterone increase and adrenal gland hypertrophy, which was dependent on both GCs and NE release induced by each stress session. CUS also increased CRF₂ mRNA expression and GR protein levels in fundamental brain structures related to HPA regulation and behavior, such as the lateral septal nucleus intermedia part (LSI), ventromedial hypothalamic nucleus (VMH), and central nucleus of the amygdala (CeA). We also showed that NE participates in the CUS-induced increase in CRF₂ and GR levels in the LSI, reinforcing the locus coeruleus (LC) involvement in the HPA axis modulation. Despite the CUS-induced molecular changes in essential areas related to anxiety-like behavior, this phenotype was not observed in CUS animals 24 h after the last stress session.

Mineralocorticoid receptors dampen glucocorticoid receptor sensitivity to stress via regulation of FKBP5

Responding to different dynamic levels of stress is critical for mammalian survival. Disruption of mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) signaling is proposed to underlie hypothalamic-pituitary-adrenal (HPA) axis dysregulation observed in stress-related psychiatric disorders. In this study, we show that FK506-binding protein 51 (FKBP5) plays a critical role in fine-tuning MR:GR balance in the hippocampus. Biotinylated-oligonucleotide immunoprecipitation in primary hippocampal neurons reveals that MR binding, rather than GR binding, to the Fkbp5 gene regulates FKBP5 expression during baseline activity of glucocorticoids. Notably, FKBP5 and MR exhibit similar hippocampal expression patterns in mice and humans, which are distinct from that of the GR. Pharmacological inhibition and region- and cell type-specific receptor deletion in mice further demonstrate that lack of MR decreases hippocampal Fkbp5 levels and dampens the stress-induced increase in glucocorticoid levels. Overall, our findings demonstrate that MR-dependent changes in baseline Fkbp5 expression modify GR sensitivity to glucocorticoids, providing insight into mechanisms of stress homeostasis.

Association of fibroblast growth factor 21 with alcohol consumption and alcohol liver cirrhosis

BACKGROUND

Fibroblast growth factor 21 (FGF21) is produced in the liver and binds to different complex receptor/coreceptor systems. Besides many other processes, FGF21 regulates the intake of simple sugars and alcohol. Increased levels of FGF21 decrease harmful alcohol intake in mice. To increase our understanding on the relationship between FGF21 and alcohol intake in humans, we aimed to measure FGF21 levels in patients with alcoholic liver cirrhosis (ALC) in comparison to patients with nonalcoholic liver cirrhosis (NALC) and healthy persons based on their present alcohol consumption.

METHODS

Alcohol intake was verified by urinary ethyl glucuronide (uETG) levels, eating and drinking behaviour by a Food Frequency Questionnaire and FGF 21 plasma levels were determined by ELISA in 96 persons (ALC n = 41; NALC n = 34; healthy n = 21).

RESULTS

Both ALC and NALC patients with elevated ETG levels (≥0.5 μg/ml; indicating alcohol consumption in the last 12-72 h) showed significantly higher FGF21 plasma levels in comparison to patients with negative ETG levels. Eating behaviour did not have an impact on FGF21 plasma levels.

CONCLUSIONS

Increased FGF21 levels in patients with recent alcohol consumption (verified by ETG) confirmed the first part of the liver-brain endocrine axis: alcohol consumption was associated with increased FGF21 levels. We could not confirm that elevated FGF21 levels were associated with reduced alcohol intake as a result. That points towards a pathology in this pathway, which might be caused by a malfunction of β‑Klotho or FGF receptors according to other studies and chronic alcohol dependency. Further research is required to clarify these pathologies, which may open new pharmacological treatment for patients with alcohol use disorder and alcohol dependence.

Effects of endogenous H2S production inhibition on the homeostatic responses induced by acute high-salt diet consumption

The gaseous modulator hydrogen sulfide (H₂S) is synthesized, among other routes, by the action of cystathionine-γ-lyase (CSE) and importantly participates in body fluid homeostasis. Therefore, the present study aimed to evaluate the participation of H₂S in behavioral, renal and neuroendocrine homeostatic responses triggered by the acute consumption of a high Na⁺ diet. After habituation, adult male Wistar rats were randomly distributed and maintained for seven days on a control [CD (0.27% of Na⁺)] or hypersodic diet [HD (0.81% of Na⁺)]. CD and HD-fed animals were treated with DL-Propargylglycine (PAG, 25 mg/kg/day, ip) or vehicle (0.9% NaCl in equivalent volume) for the same period. At the end of the experiment, animals were euthanized for blood and tissue collection. We demonstrated that a short-term increase in dietary Na⁺ intake, in values that mimic the variations in human consumption (two times the recommended) significantly modified hydroelectrolytic homeostasis, with repercussions in the hypothalamic-neurohypophysial system and hypothalamic-pituitary-adrenal axis function. These findings were accompanied by the development of a clear inflammatory response in renal tubular cells and microvascular components. On the other hand, the inhibition of the endogenous production of H₂S by CSE provided by PAG treatment prevented the inflammation induced by HD. In the kidney, PAG treatment induced the overexpression of inducible nitric oxide synthase in animals fed with HD. Taken together, these data suggest, therefore, that HD-induced H₂S production plays an important proinflammatory role in the kidney, apparently counter regulating nitric oxide actions in renal tissue.

Relation between basal cortisol and reactivity cortisol with externalizing problems: A systematic review✰

Delinquent behavior describes one of the most severe forms of antisocial and aggressive behavior, causing the highest mental health and public expenditures of problematic behavior in adolescence. Literature suggests that different concentrations of cortisol may serve as a biological marker for a severe antisocial subgroup of adolescents, although from the environmental risk factors that play a role in the development of severe delinquent and aggressive behavior, other neurobiological factors may be important. This review aims to analyze the association of cortisol levels with the development of delinquent behavior. Studies related to the topic were obtained from multiple databases, through rigorous exclusion and inclusion criteria. Only papers with empirical and quantitative methodologies from scientific and academic publications were included. Aims, methodological aspects (sample and instruments), and main conclusions were extracted from each study. Overall, the data suggest that regardless of the literature relating low cortisol levels to conduct problems and antisocial behavior, the lack of consensus in the examined studies demonstrates that more studies are needed to reveal the role of biosocial mechanisms in this hormonal-behavior link, and how these mechanisms are involved in establishing and maintaining delinquent behavior.

Identification of the Molecular Events Involved in the Development of Prefrontal Cortex Through the Analysis of RNA-Seq Data From BrainSpan

Human brain development is a complex process that follows sequential orchestration of gene expression, begins at conceptual stages, and continues into adulthood. Altered profile of gene expression drives many cellular and molecular events required for development. Here, the molecular events during development of human prefrontal cortex (PFC) (as an important executive part of the brain) were investigated. First, the RNA-sequencing data of BrainSpan were used to obtain differentially expressed genes between each two developmental stages and then, the relevant biological processes and signaling pathways were deduced by gene set enrichment analysis. In addition, the changes in transcriptome landscape of PFC during development were analyzed and the potential biological processes underlie the changes were found. Comparison of the four regions of PFC based on their biological processes showed that additional to common biological processes and signaling pathways, each PFC region had its own molecular characteristics, conforming their previously reported functional roles in brain physiology. The most heterogeneity in transcriptome between the PFC regions was observed at the time of birth which was concurrent with the activity of some region-specific regulatory systems such as DNA methylation, transcription regulation, RNA splicing, and presence of different transcription factors and microRNAs. In conclusion, this study used bioinformatics to present a comprehensive molecular overview on PFC development which may explain the etiology of brain neuropsychiatric disorders originated from malfunctioning of PFC.

Pex3 is involved in the genetic regulation of Nr3c2 expression in the amygdala of mice

The mineralocorticoid receptor (Nr3c2) has received increased attention as an important stress-related gene. Here, we sought to uncover candidate genes regulating the expression of Nr3c2. Using a genetical genomics approach, we identified a significant trans-regulated expression quantitative trait locus (eQTL) at Chromosome 10 for Nr3c2 expression in the amygdala of BXD RI strains. We then examined genes upstream of the eQTL to identify likely regulatory candidates of Nr3c2 expression. Pex3 (peroxisomal) expression was highly correlated with that of Nr3c2, had a significant cis-regulated eQTL that mapped to the Nr3c2 eQTL region and thus emerged as the most likely regulatory candidate of Nr3c2 expression. In vitro studies showed that silencing of Pex3 by siRNA decreased Nr3c2 expression in HEK293T and SHSY5 cell lines while overexpression increased Nr3c2 expression. A relationship between the expression of these two genes was further supported by our observations that expression levels of Pex3 and Nr3c2 decreased in the amygdala of mice exposed to chronic unpredictable stress. Our findings provide insight into the genetic regulation of Nr3c2 expression and suggest a new role for Pex3 in stress responses. Future characterization of Pex3's role in the regulation of Nr3c2 expression and the pathways involved may lead to a better understanding of stress responses and risk for stress-related pathology.

Mechanisms of Communication in the Mammalian Circadian Timing System

24-h rhythms in physiology and behaviour are organized by a body-wide network of endogenous circadian clocks. In mammals, a central pacemaker in the hypothalamic suprachiasmatic nucleus (SCN) integrates external light information to adapt cellular clocks in all tissues and organs to the external light-dark cycle. Together, central and peripheral clocks co-regulate physiological rhythms and functions. In this review, we outline the current knowledge about the routes of communication between the environment, the main pacemakers and the downstream clocks in the body, focusing on what we currently know and what we still need to understand about the communication mechanisms by which centrally and peripherally controlled timing signals coordinate physiological functions and behaviour. We highlight recent findings that shed new light on the internal organization and function of the SCN and neuroendocrine mechanisms mediating clock-to-clock coupling. These findings have implications for our understanding of circadian network entrainment and for potential manipulations of the circadian clock system in therapeutic settings.

On the role of corticosterone in behavioral disorders, microbiota composition alteration and neuroimmune response in adult male mice subjected to maternal separation stress

Experiencing psychosocial adversities in early life such as maternal separation (MS) increases the risk of psychiatric disorders. Immune-inflammatory responses have imperative roles in the pathophysiology of psychiatric disorders. MS relatively changes the composition of intestinal microbiota leading to an overactivation of the hypothalamic-pituitary-adrenal (HPA) axis, and subsequently increases the corticosterone level. In this study, we aimed to evaluate the role of corticosterone in behavioral changes and microbiota modifications in a mouse model of MS afflicted neuroinflammatory response in the hippocampus. For this purpose, 180 min of MS stress was applied to mice at postnatal day (PND) 2-14 followed by behavioral tests including forced swimming test (FST), splash test, open field test (OFT) and elevated plus maze (EPM) at PND 50-52. For evaluating the role of corticosterone, mice were subjected to adrenalectomy. Using real-time RT-PCR, the expression of inflammatory genes was determined in the hippocampus and colon tissues. We found that MS provoked depressive- and anxiety-like behaviors in adult male mice. In addition, MS was able to active a neuroimmune response in the hippocampus, motivate inflammation and histopathologic changes in the colon tissue and modify the composition of gut microbiota as well. Interestingly, our findings showed that adrenalectomy (decline in the corticosterone level), could modulate the above-mentioned negative effects of MS. In conclusion, our results demonstrated that overactivation of HPA axis and the subsequent increased level of corticosterone could act, possibly, as the deleterious effects of MS on behavior, microbiota composition changes and activation of neuroimmune response.

Basic fibroblast growth factor increased glucocorticoid receptors in cortical neurons through MAP kinase pathway

Prolonged and intense stress chronically increases blood concentration of glucocorticoids, which in turn causes downregulation of glucocorticoid receptor (GR) in the central nervous system (CNS). This process has been suggested to be involved in the pathogenesis of major depressive disorder (MDD). Here, we found that basic fibroblast growth factor (bFGF) increased the expression of GR in the rat cerebral cortex and cultured cortical neurons and restored the reduced GR expression caused by glucocorticoid exposure. Among intracellular signaling pathways stimulated by bFGF, extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway was responsible for the upregulation of GR. The bFGF-induced GR was functional as a transcription factor to enhance transcription of a target gene. Because high stress augments bFGF levels in the brain, it is likely that bFGF plays a compensating role for reduced GR expression after stress and thus should be studied as a therapeutic target for the treatment of MDD.

Disrupted-in-Schizophrenia-1 is essential for normal hypothalamic-pituitary-interrenal (HPI) axis function

Psychiatric disorders arise due to an interplay of genetic and environmental factors, including stress. Studies in rodents have shown that mutants for Disrupted-In-Schizophrenia-1 (DISC1), a well-accepted genetic risk factor for mental illness, display abnormal behaviours in response to stress, but the mechanisms through which DISC1 affects stress responses remain poorly understood. Using two lines of zebrafish homozygous mutant for disc1, we investigated behaviour and functioning of the hypothalamic-pituitary-interrenal (HPI) axis, the fish equivalent of the hypothalamic-pituitary-adrenal (HPA) axis. Here, we show that the role of DISC1 in stress responses is evolutionarily conserved and that DISC1 is essential for normal functioning of the HPI axis. Adult zebrafish homozygous mutant for disc1 show aberrant behavioural responses to stress. Our studies reveal that in the embryo, disc1 is expressed in neural progenitor cells of the hypothalamus, a conserved region of the vertebrate brain that centrally controls responses to environmental stressors. In disc1 mutant embryos, proliferating rx3+ hypothalamic progenitors are not maintained normally and neuronal differentiation is compromised: rx3-derived ff1b+ neurons, implicated in anxiety-related behaviours, and corticotrophin releasing hormone (crh) neurons, key regulators of the stress axis, develop abnormally, and rx3-derived pomc+ neurons are disorganised. Abnormal hypothalamic development is associated with dysfunctional behavioural and neuroendocrine stress responses. In contrast to wild type siblings, disc1 mutant larvae show altered crh levels, fail to upregulate cortisol levels when under stress and do not modulate shoal cohesion, indicative of abnormal social behaviour. These data indicate that disc1 is essential for normal development of the hypothalamus and for the correct functioning of the HPA/HPI axis.

High hair cortisol concentrations predict worse cognitive outcome after stroke: Results from the TABASCO prospective cohort study

BACKGROUND AND PURPOSE

The role of stress-related endocrine dysregulation in the development of cognitive changes following a stroke needs further elucidation. We explored this issue in a longitudinal study on stroke survivors using hair cortisol concentrations (HCC), a measure of integrated long-term cortisol levels.

METHODS

Participants were consecutive cognitively intact first-ever mild-moderate ischemic stroke/transient ischemic attack (TIA) survivors from the Tel Aviv Brain Acute Stroke Cohort (TABASCO) study. They underwent 3T magnetic resonance imaging (MRI) scanning and were cognitively assessed at admission, and at 6, 12 and 24 months post-stroke. Scalp hair samples were obtained during the initial hospitalization.

RESULTS

Full data on baseline HCC, MRI scans and 2 years neuropsychological assessments were available for 65 patients. Higher HCC were significantly associated with a larger lesion volume and with worse cognitive results 6, 12 and 24 months post-stroke on most of the neurocognitive tests. 15.4% of the participants went on to develop clinically significant cognitive decline in the follow-up period, and higher HCC at baseline were found to be a significant risk factor for this decline, after adjustment for age, gender, body mass index and APOE e4 carrier status (HR=6.553, p=0.038).

CONCLUSIONS

Our findings suggest that individuals with higher HCC, which probably reflect higher long-term cortisol release, are prone to develop cognitive decline following an acute stroke or TIA.

Muscle Pathology in Free-Ranging Stranded Cetaceans

Despite the profound impact that skeletal muscle disorders may pose for the daily activities of wild terrestrial and marine mammals, such conditions have been rarely described in cetaceans. In this study, the authors aimed to determine the nature and prevalence of skeletal muscle lesions in small and large odontocetes and mysticetes ( n = 153) from 19 different species. A macroscopic evaluation of the epaxial muscle mass and a histologic examination of the longissimus dorsi muscle were performed in all cases. The only macroscopically evident change was variable degrees of atrophy of the epaxial muscles ( longissimus dorsi, multifidus, spinalis) in emaciated specimens. The histopathological study revealed single or combined morphological changes in 91.5% of the cases. These changes included the following: degenerative lesions (75.2%), muscle atrophy (37.9%), chronic myopathic changes (25.5%), parasitic infestation (9.2%), and myositis (1.9%). The skeletal muscle is easily sampled during a necropsy and provides essential microscopic information that reflects both local and systemic conditions. Thus, skeletal muscle should be systematically sampled, processed, and examined in all stranded cetaceans.

Stress and Adaptation

Animal models have contributed considerably to the current understanding of mechanisms underlying the role of stress in health and disease. Despite the progress made already, much more can be made by more carefully exploiting animals' and humans' shared biology, using ecologically relevant models. This allows a fundamental analysis of factors modulating individual adaptive capacity and hence individual vulnerability to disease. This article highlights an emerging scientific approach that uses a framework of interpretation that is more biologically oriented than previous approaches, to evaluate both the adaptive and maladaptive nature of the stress response in relation to existing environmental demands.

Mood Disorders in Uncontrolled Hypertension Despite Multiple Anti-Hypertensive Medications: Searching for a Link

INTRODUCTION

Resistant hypertension is a clinical condition in which blood pressure (BP) control is not achieved under a pharmacological therapy including a diuretic and at least two additional antihypertensive drug classes.

AIM

To discuss an unusual presentation of uncontrolled hypertension despite multiple anti-hypertensive medications.

METHODS AND RESULTS

A 46-year-old woman presented with resistant hypertension (HT) and with a long history of polydipsia, polyuria, weight loss and psychiatric symptoms (sudden onset of personality disorder with free anxiety, negativism and asthenia) unsuccessfully treated with antidepressant drugs. Tests for secondary HT showed a marked increase of serum renin and aldosterone both in clinostatic (342 pg/ml and 907 pmol/l, respectively) and orthostatic posture (351 pg/ml and 2845 pmol/l, respectively), hypokalemia (2.9 mmol/l) and macroalbuminuria (431 mg/day). Diagnostic examinations also revealed a focal stenosis of approximately 70 % of the proximal right renal artery with post-stenotic dilation. After percutaneous balloon angioplasty and stent implantation, BP was normalized with 5 mg/day amlodipine and psychiatric symptoms suddenly disappeared.

CONCLUSIONS

Psychopathological symptoms are rare at the onset of hyperaldosteronism, and their aetiology is not well defined. A proper diagnostic and therapeutic process is mandatory in order to get the recommended therapeutic targets in short-midterm improving long-term prognosis. We also suggest not considering depressed or treat with antidepressant agents a young hypertensive subject with uncontrolled hypertension despite multiple anti-hypertensive medications without having ruled out a secondary form of hypertension.

Stress Effects on Multiple Memory System Interactions

Extensive behavioural, pharmacological, and neurological research reports stress effects on mammalian memory processes. While stress effects on memory quantity have been known for decades, the influence of stress on multiple memory systems and their distinct contributions to the learning process have only recently been described. In this paper, after summarizing the fundamental biological aspects of stress/emotional arousal and recapitulating functionally and anatomically distinct memory systems, we review recent animal and human studies exploring the effects of stress on multiple memory systems. Apart from discussing the interaction between distinct memory systems in stressful situations, we will also outline the fundamental role of the amygdala in mediating such stress effects. Additionally, based on the methods applied in the herein discussed studies, we will discuss how memory translates into behaviour.

Gut Microbiota: A Modulator of Brain Plasticity and Cognitive Function in Ageing

Gut microbiota have recently been a topic of great interest in the field of microbiology, particularly their role in normal physiology and its influence on human health in disease. A large body of research has supported the presence of a pathway of communication between the gut and the brain, modulated by gut microbiota, giving rise to the term “microbiota-gut-brain” axis. It is now thought that, through this pathway, microbiota can affect behaviour and modulate brain plasticity and cognitive function in ageing. This review summarizes the evidence supporting the existence of such a connection and possible mechanisms of action whereby microbiota can influence the function of the central nervous system. Since normalisation of gut flora has been shown to prevent changes in behaviour, we further postulate on possible therapeutic targets to intervene with cognitive decline in ageing. The research poses various limitations, for example uncertainty about how this data translates to broad human populations. Nonetheless, the microbiota-gut-brain axis is an exciting field worthy of further investigation, particularly with regards to its implications on the ageing population.

The role of glucocorticoid receptor-dependent activity in the amygdala central nucleus and reversibility of early-life stress programmed behavior

Early-life stress (ELS) leads to sustained changes in gene expression and behavior, increasing the likelihood of developing a psychiatric disorder in adulthood. The neurobiological basis for the later-in-life psychopathology is relatively unknown. The current study used a mouse model of ELS, achieved by daily maternal separations during the first 2 weeks of postnatal life, to test the role of amygdalar glucocorticoid receptor (GR) function in mediating the persistent increase in risk-taking behaviors. ELS produced a decrease in GR mRNA in the brain, with a notable reduction in the amygdala that was associated with sustained alterations in anxiety, fear and sociability-like behaviors. Lentiviral-mediated restoration of the GR mRNA deficit, specifically within the adult central nucleus of the amygdala (CeA), reversed the enduring changes in anxiety and social behavior after ELS. These results provide evidence of lasting changes in CeA GR neural circuitry following ELS and suggest a mechanistic role for GR-regulated processes in the CeA in mediating the lifelong maladaptive behaviors of ELS. We demonstrate that the long-lasting behavioral effects of ELS are reversible later in life and implicate the involvement of CeA GR-dependent activity in the sustained dysregulation of emotion following ELS.

A novel 2-decenoic acid thioester ameliorates corticosterone-induced depression- and anxiety-like behaviors and normalizes reduced hippocampal signal transduction in treated mice

We characterized mice administered corticosterone (CORT) at a dose of 20 mg/kg for 3 weeks to determine their suitability as a model of mood disorders and found that the time immobilized in the tail suspension test was longer and the time spent in the open arms of the elevated plus-maze test was shorter than those of the vehicle-treated group, findings demonstrating that chronic CORT induced both depression-like and anxiety-like behaviors. Furthermore, the levels of phosphorylated extracellular signal-regulated kinase (pERK) 1/2 in the hippocampus and cerebral cortex were reduced in the CORT-treated group. Using this model, we investigated the protective effect of the ester, thioester, and amide compounds of 2-decenoic acid derivatives (termed compounds A, B, and C, respectively). The potency of the protective activity against the CORT-induced depression-like or anxiety-like behaviors and the reduction in pERK1/2 level were found to be in the following order: compound B > compound C > compound A. Therefore, we further investigated the therapeutic activity of only compound B, and its effect on depression-like behavior was observed after oral administration for 1 or 2 weeks, and its effect on anxiety-like behavior was observed after oral administration for 3 weeks. The ratios of phosphorylated ERK1/2, Akt, and cAMP-response element-binding protein to their respective nonphosphorylated forms were smaller in the CORT-treated group than in the vehicle-treated group; however, subsequent treatment with compound B at either 0.3 or 1.5 mg/kg significantly ameliorated this reduction. Compound B appeared to elicit intracellular signaling, similar to that elicited by brain-derived neurotrophic factor, and its mode of action was shown to be novel and different from that of fluvoxamine, a currently prescribed drug for mood disorders.

Sex differences in the HPA axis

The hypothalamic-pituitary-adrenal (HPA) axis is a major component of the systems that respond to stress, by coordinating the neuroendocrine and autonomic responses. Tightly controlled regulation of HPA responses is critical for maintaining mental and physical health, as hyper- and hypo-activity have been linked to disease states. A long history of research has revealed sex differences in numerous components of the HPA stress system and its responses, which may partially form the basis for sex disparities in disease development. Despite this, many studies use male subjects exclusively, while fewer reports involve females or provide direct sex comparisons. The purpose of this article is to present sex comparisons in the functional and molecular aspects of the HPA axis, through various phases of activity, including basal, acute stress, and chronic stress conditions. The HPA axis in females initiates more rapidly and produces a greater output of stress hormones. This review focuses on the interactions between the gonadal hormone system and the HPA axis as the key mediators of these sex differences, whereby androgens increase and estrogens decrease HPA activity in adulthood. In addition to the effects of gonadal hormones on the adult response, morphological impacts of hormone exposure during development are also involved in mediating sex differences. Additional systems impinging on the HPA axis that contribute to sex differences include the monoamine neurotransmitters norepinephrine and serotonin. Diverse signals originating from the brain and periphery are integrated to determine the level of HPA axis activity, and these signals are, in many cases, sex-specific.

Is Dysregulation of the HPA-Axis a Core Pathophysiology Mediating Co-Morbid Depression in Neurodegenerative Diseases?

There is increasing evidence of prodromal manifestation of neuropsychiatric symptoms in a variety of neurodegenerative diseases such as Parkinson's disease (PD) and Huntington's disease (HD). These affective symptoms may be observed many years before the core diagnostic symptoms of the neurological condition. It is becoming more apparent that depression is a significant modifying factor of the trajectory of disease progression and even treatment outcomes. It is therefore crucial that we understand the potential pathophysiologies related to the primary condition, which could contribute to the development of depression. The hypothalamic-pituitary-adrenal (HPA)-axis is a key neuroendocrine signaling system involved in physiological homeostasis and stress response. Disturbances of this system lead to severe hormonal imbalances, and the majority of such patients also present with behavioral deficits and/or mood disorders. Dysregulation of the HPA-axis is also strongly implicated in the pathology of major depressive disorder. Consistent with this, antidepressant drugs, such as the selective serotonin reuptake inhibitors have been shown to alter HPA-axis activity. In this review, we will summarize the current state of knowledge regarding HPA-axis pathology in Alzheimer's, PD and HD, differentiating between prodromal and later stages of disease progression when evidence is available. Both clinical and preclinical evidence will be examined, but we highlight animal model studies as being particularly useful for uncovering novel mechanisms of pathology related to co-morbid mood disorders. Finally, we purpose utilizing the preclinical evidence to better inform prospective, intervention studies.

Associations between self-reported discrimination and diurnal cortisol rhythms among young adults: The moderating role of racial-ethnic minority status

Discrimination is theorized to set in motion a neuroendocrine response, which includes cortisol secretion from the hypothalamic-pituitary-adrenal axis. Repeated exposure to perceived discrimination is thought to contribute to alterations in diurnal cortisol rhythms and to have implications for health. Discrimination may have particularly strong effects on racial/ethnic minority individuals, based on histories of past exposure and/or greater perceived implications of discriminatory events. Utilizing an ethnically and racially diverse sample of young adults (N=140; Mage=22.8 years) and a multiple-day naturalistic cortisol protocol, the present study examined associations between self-reported discrimination and diurnal cortisol rhythms, and whether this relation was moderated by racial/ethnic minority status. Results revealed that self-reported discrimination predicted flatter diurnal cortisol slopes for racial/ethnic minority individuals only. These findings align with theory suggesting that discrimination experiences are important among racial/ethnic minorities.

Probiotics normalize the gut-brain-microbiota axis in immunodeficient mice

The gut-brain-microbiota axis is increasingly recognized as an important regulator of intestinal physiology. Exposure to psychological stress causes activation of the hypothalamic-pituitary-adrenal (HPA) axis and causes altered intestinal barrier function, intestinal dysbiosis, and behavioral changes. The primary aim of this study was to determine whether the effects of psychological stress on intestinal physiology and behavior, including anxiety and memory, are mediated by the adaptive immune system. Furthermore, we wanted to determine whether treatment with probiotics would normalize these effects. Here we demonstrate that B and T cell-deficient Rag1(-/-) mice displayed altered baseline behaviors, including memory and anxiety, accompanied by an overactive HPA axis, increased intestinal secretory state, dysbiosis, and decreased hippocampal c-Fos expression. Both local (intestinal physiology and microbiota) and central (behavioral and hippocampal c-Fos) changes were normalized by pretreatment with probiotics, indicating an overall benefit on health conferred by changes in the microbiota, independent of lymphocytes. Taken together, these findings indicate a role for adaptive immune cells in maintaining normal intestinal and brain health in mice and show that probiotics can overcome this immune-mediated deficit in the gut-brain-microbiota axis.

Histopathological muscle findings may be essential for a definitive diagnosis of suspected sharp trauma associated with ship strikes in stranded cetaceans

Ship strikes are a major issue for the conservation of may cetacean species. Certain gross and microscopic criteria have been previously reported for establishing a diagnosis of death due to ship strikes in these animals. However, some ship-strike injuries may be masked by advanced carcass decomposition and may be undetectable due to restricted access to the animals. In this report we describe histopathological muscular findings in 13 cetaceans with sharp trauma from ship strikes as the cause of death. Skeletal muscle samples were taken from the incision site and from the main locomotor muscle, the longissimus dorsi, in areas not directly affected by the sharp injury. The microscopic findings in tissues from both sites mainly consisted of haemorrhages; oedema; flocculent, granular or/and hyalinised segmentary degeneration; contraction band necrosis; and discoid degeneration or fragmentation of myofibres. We propose that skeletal muscle histopathology provides evidence of ante-mortem injuries even if the sample was taken elsewhere in the carcass and not only within or adjacent to the sharp trauma site and despite the advanced decomposition of some of the carcasses. This method helps to establish the diagnosis of ship strike as the cause of death.

Sex differences in activation of the hypothalamic-pituitary-adrenal axis by methamphetamine

Dysregulation of hypothalamic-pituitary-adrenal (HPA) axis activation is associated with changes in addiction-related behaviors. In this study, we tested whether sex differences in the acute effects of methamphetamine (MA) exposure involve differential activation of the HPA axis. Male and female mice were injected with MA (1 mg/kg) or saline for comparison of plasma corticosterone and analysis of the immediate early gene c-Fos in brain. There was a prolonged elevation in corticosterone levels in female compared to male mice. C-Fos was elevated in both sexes following MA in HPA axis-associated regions, including the hypothalamic paraventricular nucleus (PVN), central amygdala, cingulate, and CA3 hippocampal region. MA increased the number of c-Fos and c-Fos/glucocorticoid receptor (GR) dual-labeled cells to a greater extent in males than females in the cingulate and CA3 regions. MA also increased the number of c-fos/vasopressin dual-labeled cells in the PVN as well as the number and percentage of c-Fos/GR dual-labeled cells in the PVN and central amygdala, although no sex differences in dual labeling were found in these regions. Thus, sex differences in MA-induced plasma corticosterone levels and activation of distinct brain regions and proteins involved in HPA axis regulation may contribute to sex differences in acute effects of MA on the brain. Methamphetamine induces a prolonged plasma corticosterone response in females compared to males. This may be mediated by increased neural activation, involving a greater activation of glucocorticoid receptor-positive cells, in males in the CA3 and cingulate brain regions, which are involved in negative feedback functions. These findings indicate a sex difference in the neural regulation of methamphetamine-induced plasma corticosterone release.

Early-Life Stress, HPA Axis Adaptation, and Mechanisms Contributing to Later Health Outcomes

Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, which then modulates the degree of adaptation and response to a later stressor. It is known that early-life stress can impact on later health but less is known about how early-life stress impairs HPA axis activity, contributing to maladaptation of the stress-response system. Early-life stress exposure (either prenatally or in the early postnatal period) can impact developmental pathways resulting in lasting structural and regulatory changes that predispose to adulthood disease. Epidemiological, clinical, and experimental studies have demonstrated that early-life stress produces long term hyper-responsiveness to stress with exaggerated circulating glucocorticoids, and enhanced anxiety and depression-like behaviors. Recently, evidence has emerged on early-life stress-induced metabolic derangements, for example hyperinsulinemia and altered insulin sensitivity on exposure to a high energy diet later in life. This draws our attention to the contribution of later environment to disease vulnerability. Early-life stress can alter the expression of genes in peripheral tissues, such as the glucocorticoid receptor and 11-beta hydroxysteroid dehydrogenase (11β-HSD1). We propose that interactions between altered HPA axis activity and liver 11β-HSD1 modulates both tissue and circulating glucocorticoid availability, with adverse metabolic consequences. This review discusses the potential mechanisms underlying early-life stress-induced maladaptation of the HPA axis, and its subsequent effects on energy utilization and expenditure. The effects of positive later environments as a means of ameliorating early-life stress-induced health deficits, and proposed mechanisms underpinning the interaction between early-life stress and subsequent detrimental environmental exposures on metabolic risk will be outlined. Limitations in current methodology linking early-life stress and later health outcomes will also be addressed.

Mineralocorticoid receptor blockade prevents stress-induced modulation of multiple memory systems in the human brain

BACKGROUND

Accumulating evidence suggests that stress may orchestrate the engagement of multiple memory systems in the brain. In particular, stress is thought to favor dorsal striatum-dependent procedural over hippocampus-dependent declarative memory. However, the neuroendocrine mechanisms underlying these modulatory effects of stress remain elusive, especially in humans. Here, we targeted the role of the mineralocorticoid receptor (MR) in the stress-induced modulation of dorsal striatal and hippocampal memory systems in the human brain using a combination of event-related functional magnetic resonance imaging and pharmacologic blockade of the MR.

METHODS

Eighty healthy participants received the MR antagonist spironolactone (300 mg) or a placebo and underwent a stressor or control manipulation before they performed, in the scanner, a classification task that can be supported by the hippocampus and the dorsal striatum.

RESULTS

Stress after placebo did not affect learning performance but reduced explicit task knowledge and led to a relative increase in the use of more procedural learning strategies. At the neural level, stress promoted striatum-based learning at the expense of hippocampus-based learning. Functional connectivity analyses showed that this shift was associated with altered coupling of the amygdala with the hippocampus and dorsal striatum. Mineralocorticoid receptor blockade before stress prevented the stress-induced shift toward dorsal striatal procedural learning, same as the stress-induced alterations of amygdala connectivity with hippocampus and dorsal striatum, but resulted in significantly impaired performance.

CONCLUSIONS

Our findings indicate that the stress-induced shift from hippocampal to dorsal striatal memory systems is mediated by the amygdala, required to preserve performance after stress, and dependent on the MR.

Thyrotropin secretion patterns in health and disease

Thyroid hormones are extremely important for metabolism, development, and growth during the lifetime. The hypothalamo-pituitary-thyroid axis is precisely regulated for these purposes. Much of our knowledge of this hormonal axis is derived from experiments in animals and mutations in man. This review examines the hypothalamo-pituitary-thyroid axis particularly in relation to the regulated 24-hour serum TSH concentration profiles in physiological and pathophysiological conditions, including obesity, primary hypothyroidism, pituitary diseases, psychiatric disorders, and selected neurological diseases. Diurnal TSH rhythms can be analyzed with novel and precise techniques, eg, operator-independent deconvolution and approximate entropy. These approaches provide indirect insight in the regulatory components in pathophysiological conditions.

Activity-dependent, stress-responsive BDNF signaling and the quest for optimal brain health and resilience throughout the lifespan

During development of the nervous system, the formation of connections (synapses) between neurons is dependent upon electrical activity in those neurons, and neurotrophic factors produced by target cells play a pivotal role in such activity-dependent sculpting of the neural networks. A similar interplay between neurotransmitter and neurotrophic factor signaling pathways mediates adaptive responses of neural networks to environmental demands in adult mammals, with the excitatory neurotransmitter glutamate and brain-derived neurotrophic factor (BDNF) being particularly prominent regulators of synaptic plasticity throughout the central nervous system. Optimal brain health throughout the lifespan is promoted by intermittent challenges such as exercise, cognitive stimulation and dietary energy restriction, that subject neurons to activity-related metabolic stress. At the molecular level, such challenges to neurons result in the production of proteins involved in neurogenesis, learning and memory and neuronal survival; examples include proteins that regulate mitochondrial biogenesis, protein quality control, and resistance of cells to oxidative, metabolic and proteotoxic stress. BDNF signaling mediates up-regulation of several such proteins including the protein chaperone GRP-78, antioxidant enzymes, the cell survival protein Bcl-2, and the DNA repair enzyme APE1. Insufficient exposure to such challenges, genetic factors may conspire to impair BDNF production and/or signaling resulting in the vulnerability of the brain to injury and neurodegenerative disorders including Alzheimer's, Parkinson's and Huntington's diseases. Further, BDNF signaling is negatively regulated by glucocorticoids. Glucocorticoids impair synaptic plasticity in the brain by negatively regulating spine density, neurogenesis and long-term potentiation, effects that are potentially linked to glucocorticoid regulation of BDNF. Findings suggest that BDNF signaling in specific brain regions mediates some of the beneficial effects of exercise and energy restriction on peripheral energy metabolism and the cardiovascular system. Collectively, the findings described in this article suggest the possibility of developing prescriptions for optimal brain health based on activity-dependent BDNF signaling.

Glucocorticoid-related molecular signaling pathways regulating hippocampal neurogenesis

Stress and glucocorticoid hormones regulate hippocampal neurogenesis, but the molecular mechanisms underlying their effects are unknown. We, therefore, investigated the molecular signaling pathways mediating the effects of cortisol on proliferation, neuronal differentiation, and astrogliogenesis, in an immortalized human hippocampal progenitor cell line. In addition, we examined the molecular signaling pathways activated in the hippocampus of prenatally stressed rats, characterized by persistently elevated glucocorticoid levels in adulthood. In human hippocampal progenitor cells, we found that low concentrations of cortisol (100 nM) increased proliferation (+16%), decreased neurogenesis into microtubule-associated protein 2 (MAP2)-positive neurons (-24%) and doublecortin (Dcx)-positive neuroblasts (-21%), and increased differentiation into S100β-positive astrocytes (+23%). These effects were dependent on the mineralocorticoid receptor (MR) as they were abolished by the MR antagonist, spironolactone, and mimicked by the MR-agonist, aldosterone. In contrast, high concentrations of cortisol (100 μM) decreased proliferation (-17%) and neuronal differentiation into MAP2-positive neurons (-22%) and into Dcx-positive neuroblasts (-27%), without regulating astrogliogenesis. These effects were dependent on the glucocorticoid receptor (GR), blocked by the GR antagonist RU486, and mimicked by the GR-agonist, dexamethasone. Gene expression microarray and pathway analysis showed that the low concentration of cortisol enhances Notch/Hes-signaling, the high concentration inhibits TGFβ-SMAD2/3-signaling, and both concentrations inhibit Hedgehog signaling. Mechanistically, we show that reduced Hedgehog signaling indeed critically contributes to the cortisol-induced reduction in neuronal differentiation. Accordingly, TGFβ-SMAD2/3 and Hedgehog signaling were also inhibited in the hippocampus of adult prenatally stressed rats with high glucocorticoid levels. In conclusion, our data demonstrate novel molecular signaling pathways that are regulated by glucocorticoids in vitro, in human hippocampal progenitor cells, and by stress in vivo, in the rat hippocampus.

New insights into the anti-inflammatory mechanisms of glucocorticoids: an emerging role for glucocorticoid-receptor-mediated transactivation

Glucocorticoids are anti-inflammatory drugs that are widely used for the treatment of numerous (autoimmune) inflammatory diseases. They exert their actions by binding to the glucocorticoid receptor (GR), a member of the nuclear receptor family of transcription factors. Upon ligand binding, the GR translocates to the nucleus, where it acts either as a homodimeric transcription factor that binds glucocorticoid response elements (GREs) in promoter regions of glucocorticoid (GC)-inducible genes, or as a monomeric protein that cooperates with other transcription factors to affect transcription. For decades, it has generally been believed that the undesirable side effects of GC therapy are induced by dimer-mediated transactivation, whereas its beneficial anti-inflammatory effects are mainly due to the monomer-mediated transrepressive actions of GR. Therefore, current research is focused on the development of dissociated compounds that exert only the GR monomer-dependent actions. However, many recent reports undermine this dogma by clearly showing that GR dimer-dependent transactivation is essential in the anti-inflammatory activities of GR. Many of these studies used GR(dim/dim) mutant mice, which show reduced GR dimerization and hence cannot control inflammation in several disease models. Here, we review the importance of GR dimers in the anti-inflammatory actions of GCs/GR, and hence we question the central dogma. We summarize the contribution of various GR dimer-inducible anti-inflammatory genes and question the use of selective GR agonists as therapeutic agents.

Glucocorticoid receptor BclI polymorphism associates with immunomodulatory response to stress hormone in human peripheral blood mononuclear cells

Glucocorticoid receptor (GR) variants have been found to be associated with stress-related disorders. Our previous in vivo study revealed that the CC allele of GR BclI single-nucleotide polymorphism (SNP) was more common in the high-stress group, which had lower levels of both regulatory T cells (Treg) and Th1 cytokine. The current study was to investigate the associations between GR BclI polymorphism and immunomodulatory response to stress hormone in vitro in human peripheral blood mononuclear cells (PBMC). Blood samples were collected from 18 normal volunteers including 9 subjects with BclI polymorphism GG allele and 9 with wild-type (WT) CC allele. PBMC were cultured with 10(-8) m dexamethasone (DEX), which mimics the plasma cortisol level observed during periods of psychological stress for 24 h and 11 days. Gene expressions of transcription factors, stress hormone and cytokine receptors were analysed by real-time RT-PCR. FoxP3 mRNA was significantly altered in the BclI WT (decreased at 24 h and increased at 11 days) but not in the GG allele. GR mRNA was up-regulated at 24 h and down-regulated at 11 days in CC alleles (P < 0.01 and P < 0.05), rather than in GG alleles. The expression of β-2 adrenergic receptor (β2AR) was increased at 24 h in both CC and GG alleles (P < 0.01 and P < 0.001), but decreased significantly at 11 days in only GG alleles. Expression of T-bet and GATA-3 was altered simultaneously in 24-h culture with DEX from both groups. The BclI polymorphism of GR identifies different immunomodulatory responses to corticosteroids, which may explain, at least in part, the variability in individual sensitivity to stressors.

Glucocorticoid regulation of brain-derived neurotrophic factor: relevance to hippocampal structural and functional plasticity

Glucocorticoids serve as key stress response hormones that facilitate stress coping. However, sustained glucocorticoid exposure is associated with adverse consequences on the brain, in particular within the hippocampus. Chronic glucocorticoid exposure evokes neuronal cell damage and dendritic atrophy, reduces hippocampal neurogenesis and impairs synaptic plasticity. Glucocorticoids also alter expression and signaling of the neurotrophin, brain-derived neurotrophic factor (BDNF). Since BDNF is known to promote neuroplasticity, enhance cell survival, increase hippocampal neurogenesis and cellular excitability, it has been hypothesized that specific adverse effects of glucocorticoids may be mediated by attenuating BDNF expression and signaling. The purpose of this review is to summarize the current state of literature examining the influence of glucocorticoids on BDNF, and to address whether specific effects of glucocorticoids arise through perturbation of BDNF signaling. We integrate evidence of glucocorticoid regulation of BDNF at multiple levels, spanning from the well-documented glucocorticoid-induced changes in BDNF mRNA to studies examining alterations in BDNF receptor-mediated signaling. Further, we delineate potential lines of future investigation to address hitherto unexplored aspects of the influence of glucocorticoids on BDNF. Finally, we discuss the current understanding of the contribution of BDNF to the modulation of structural and functional plasticity by glucocorticoids, in particular in the context of the hippocampus. Understanding the mechanistic crosstalk between glucocorticoids and BDNF holds promise for the identification of potential therapeutic targets for disorders associated with the dysfunction of stress hormone pathways.

Perceived discrimination and diurnal cortisol: examining relations among Mexican American adolescents

Perceived discrimination remains a salient and significant environmental stressor for ethnic and racial minority youth. Although many studies have examined the impact of racial/ethnic discrimination on mental health symptomatology and physical health, little is known of the potential physiological processes underlying such experiences, especially during adolescence. In an attempt to understand how varying perceptions of discrimination relate to functioning of the hypothalamic-pituitary-adrenal axis (HPA axis), the current study examined the relation between Mexican American adolescents' (N = 100, M(age) = 15.3 years old) perceptions of discrimination and aspects of their diurnal cortisol profiles. Three salivary samples (wakeup, +30 waking, bedtime) were collected across 3 days (total of 9 samples). Utilizing multi-level modeling, results revealed that adolescents' perceived discrimination related to greater overall cortisol output (area under the curve; AUC) after controlling for other life stressors, depressive symptoms, family income, acculturation level, daily stress levels and daily behaviors. Findings also revealed that perceived discrimination was marginally related to a steeper cortisol awakening response (CAR). Together, these findings suggest that perceived discrimination is a salient and impactful stressor for Mexican American adolescents. Understanding the physiological correlates of discrimination can provide insight into larger health disparities among ethnic and racial minority individuals.

Antidepressant-like effects of mineralocorticoid but not glucocorticoid antagonists in the lateral septum: interactions with the serotonergic system

The lateral septum (LS) is a limbic brain region that receives serotonergic projections from raphe neurons and participates in the modulation of stress responses and affective states. The present study determined whether mineralocorticoid receptors (MRs) and/or glucocorticoid receptors (GRs) located in the LS interact with the serotonergic system in the regulation of depressive-like behavior of rats subjected to the forced swimming test (FST). We also studied the effect of corticosterone release induced by the FST on MR- and GR-mRNA expression in the LS. Specifically, we studied the antidepressant-like effects of spironolactone (a MR antagonist), mifepristone (a GR antagonist), and the antidepressant clomipramine (CMI) administered directly into the LS. In addition, spironolactone and CMI actions were studied in animals with serotonergic depletion induced by dl-p-chlorophenylalanine (pCPA). Finally, adrenalectomized and Sham-operated rats were subjected to the FST to determine MR- and GR-mRNA expression in the LS at different post-FST intervals. The results showed that intraseptal injection of spironolactone, but not mifepristone induced antidepressant-like actions in the FST; this effect was blocked by pCPA treatment. CMI and spironolactone increased 5-HT concentrations in the LS of rats subjected to the FST. Increases in corticosterone release, induced by the FST, correlated with a decrease in MR-mRNA expression in the LS; no correlation was found with GR-mRNA expression. In conclusion, MRs in the lateral septum, but not GRs, participate in the regulation of depressive-like behavior of animals subjected to the FST. Both serotonin and corticosterone play an important role in MR actions in the LS.

Serotonergic neurotransmission in the ventral hippocampus is enhanced by corticosterone and altered by chronic amphetamine treatment

The ventral hippocampus modulates anxiety-like behavior in rats, and serotonergic transmission within the hippocampus facilitates adaptation to stress. Chronic amphetamine treatment results in anxiety-like behavior in rats and reduced monoamine concentrations in the ventral hippocampus. Since reduced hippocampal serotonergic transmission in response to stress is observed in rats that display high anxiety-like behavior, anxiety states in amphetamine-treated rats may be associated with reduced stress-related serotonergic transmission in the hippocampus. Therefore, using in vivo microdialysis in anesthetized rats, we investigated the effect of corticosterone infused locally into the ventral hippocampus on serotonergic transmission, and the effect of chronic amphetamine pretreatment on corticosteroid receptor protein expression and the corticosterone-induced serotonergic response. Extracellular serotonin in the ventral hippocampus was increased by corticosterone in drug naive rats, and this corticosterone-induced serotonin augmentation was blocked by the glucocorticoid receptor antagonist mifepristone. Furthermore, chronic pretreatment with amphetamine abolished the serotonin response to physiologically relevant corticosterone levels and reduced glucocorticoid receptor protein expression. Together, our results suggest that chronic amphetamine exposure reduces serotonergic neurotransmission, in part via alterations to glucocorticoid receptor-facilitation of serotonin release in the rat ventral hippocampus. Reduced serotonergic activity in the ventral hippocampus may contribute to altered stress responses and adaptive coping following repeated drug exposure.

Chronic stress and environmental enrichment as opposite factors affecting the immune response in Japanese quail (Coturnix coturnix japonica)

Procedures in the commercial production of animals involve stressful situations which lessen the animal's welfare. This study on Japanese quail evaluated whether an environmental enrichment manipulation can affect avian immune responses and if combined with a chronic stressor exposure can help to counteract the negative effects of stress on the immune system. Potential gender effects were also considered. After hatch, half of the birds were housed in non-enriched boxes and half were housed in environmentally enriched boxes. From day 33 to 42 of age, all birds within half of the non-enriched and enriched boxes remained undisturbed while the other half were daily exposed to a 15 min restraint stressor (chronic stressor). The inflammatory response (lymphoproliferation after phytohemagglutinin-p), percentage of lymphocytes, heterophil/lymphocyte (H/L) ratio and primary antibody response against sheep red blood cells were assessed. The chronic stressor application and the enrichment procedure, respectively, either increased or reduced the four immunological parameters evaluated and always in opposite directions. Males consistently showed lower antibody titres than females and presented the highest H/L ratio in response to the stressor when reared in the non-enriched environment. The findings indicate that submitting these animals to an enriched environment can be effectively used to improve their immune response and to reduce the detrimental effects of a stressor exposure.

Effects of mental workload on long-latency auditory-evoked-potential, salivary cortisol, and immunoglobulin A

This paper researches on the effects of mental workload on long-latency auditory-evoked-potential (AEP), salivary cortisol, and immunoglobulin A (IgA). 20 Healthy subjects (11 males and 9 females) participated in the experiment voluntarily. The mental task consisted of two parts: arithmetic task and reading comprehension task. The Latencies of N1, P2, N2, P3, and mismatch negativity (MMN) all increased significantly after the mental tasks were adopted at all of the three recording sites: Cz, Fz, and Pz (p<0.05). In this experiment, changes of salivary cortisol and s-IgA levels due to mental tasks were not significant. With the introduction of mental tasks, more processing resources are allocated to the primary task (mental task), and decreased processing resources available for the secondary task (auditory task), which is reflected on the increases in the latencies of probe-evoked AEP components.

Psychogenetics of post-traumatic stress disorder: a short review

Post-traumatic stress disorder is a commonly overlooked psychiatric disorder due to the heterogeneity of symptoms that may simulate many other psychiatric disorders. Such heterogeneity of manifestations may be explained by the multifaceted nature of the different neurotransmitters, endocrinologic axis, and their genetic basis, that are implicated in the etiology. Although this disorder has been studied from many different perspectives, its etiology is still enigmatic. This minireview demonstrates, in brief, that different susceptibility genes are associated with post traumatic stress disorder.

Myeloid mineralocorticoid receptor controls macrophage polarization and cardiovascular hypertrophy and remodeling in mice

Inappropriate excess of the steroid hormone aldosterone, which is a mineralocorticoid receptor (MR) agonist, is associated with increased inflammation and risk of cardiovascular disease. MR antagonists are cardioprotective and antiinflammatory in vivo, and evidence suggests that they mediate these effects in part by aldosterone-independent mechanisms. Here we have shown that MR on myeloid cells is necessary for efficient classical macrophage activation by proinflammatory cytokines. Macrophages from mice lacking MR in myeloid cells (referred to herein as MyMRKO mice) exhibited a transcription profile of alternative activation. In vitro, MR deficiency synergized with inducers of alternatively activated macrophages (for example, IL-4 and agonists of PPARgamma and the glucocorticoid receptor) to enhance alternative activation. In vivo, MR deficiency in macrophages mimicked the effects of MR antagonists and protected against cardiac hypertrophy, fibrosis, and vascular damage caused by L-NAME/Ang II. Increased blood pressure and heart rates and decreased circadian variation were observed during treatment of MyMRKO mice with L-NAME/Ang II. We conclude that myeloid MR is an important control point in macrophage polarization and that the function of MR on myeloid cells likely represents a conserved ancestral MR function that is integrated in a transcriptional network with PPARgamma and glucocorticoid receptor. Furthermore, myeloid MR is critical for blood pressure control and for hypertrophic and fibrotic responses in the mouse heart and aorta.