The glucocorticoid receptor: part of the solution or part of the problem?

Potential role of gut microbiota in major depressive disorder: A review

Interactions between the gut microbiota and host immunity are sophisticated, dynamic, and host-dependent. Scientists have recently conducted research showing that disturbances in the gut bacterial community can lead to a decrease in some metabolites and, consequently, to behaviors such as depression. Exposure to stressors dropped the relative abundance of bacteria in the genus Bacteroides while soaring the relative abundance of bacteria in the genus Clostridium, Coprococcus, Dialister, and Oscillibacter, which were also reduced in people with depression. Microbiota and innate immunity are in a bilateral relationship. The gut microbiota has been shown to induce the synthesis of antimicrobial proteins such as catalysidins, type C lectins, and defensins. Probiotic bacteria can modulate depressive behavior through GABA signaling. The gut microbiome produces essential metabolites such as neurotransmitters, tryptophan metabolites, and short-chain fatty acids (SCFAs) that can act on the CNS. In the case of dysbiosis, due to mucin changes, the ratio of intestinal-derived molecules may change and contribute to depression. Psychotropics, including Bifidobacterium longum NCC3001, Clostridium butyricum CBM588, and Lactobacillus acidophilus, have mental health benefits, and can have a positive effect on the host-brain relationship, and have antidepressant effects. This article reviews current studies on the association between gut microbiota dysbiosis and depression. Comprehensively, these findings could potentially lead to novel approaches to improving depressive symptoms via gut microbiota alterations, including probiotics, prebiotics, and fecal microbiota transplantation.

Exploratory Clinical Trial of a Depression Diagnostic Software That Integrates Stress Biomarkers and Composite Psychometrics

OBJECTIVE

This study evaluated the clinical effectiveness of Minds.NAVI, a depression screening kit combining psychometric measures and stress hormone biomarkers, in a prospective clinical trial. The objective was to assess its potential as a depression screening tool and investigate the associations between psychological assessments, salivary hormone staging, and depression severity.

METHODS

Thirty-five participants with major depressive disorder and 12 healthy controls (HCs) were included. The Minds.NAVI software, utilizing the PROtective and Vulnerable factors battEry Test (PROVE) and salivary cortisol/dehydroepiandrosterone (DHEA) analysis, was employed. The PROVE test is a comprehensive self-report questionnaire that assesses depressive symptoms, suicide risk, attachment style, adverse childhood experiences, mentalization capacity, and resilience. In addition, salivary cortisol and DHEA levels were measured to evaluate the functional stage of the hypothalamic-pituitary-adrenal (HPA) axis.

RESULTS

Minds.NAVI exhibited 100% sensitivity, 91.7% specificity, and 97.9% accuracy in distinguishing depression from HCs within an exploratory small group. Salivary stress hormone phases showed changes with depression stage (p=0.030), and the proportion of patients with "adrenal exhaustion stage" was higher in the moderate/severe depression group (p=0.038). Protective/vulnerable factors differed significantly between controls and depressed groups (p<0.001). Cortisol awakening response inversely correlated with depressive symptom severity (r=-0.31, p=0.034).

CONCLUSION

This study suggested possible clinical effectiveness of Minds.NAVI, a depression screening tool that integrates psychometric measures and stress hormone biomarkers. The findings support the potential association between depression, chronic stress, and HPA axis hyporesponsiveness.

Opioid Mechanisms and the Treatment of Depression

Opioid receptors are widely expressed in the brain, and the opioid system has a key role in modulating mood, reward processing and stress responsivity. There is mounting evidence that the endogenous opioid system may be dysregulated in depression and that drug treatments targeting mu, delta and kappa opioid receptors may show antidepressant potential. The mechanisms underlying the therapeutic effects of opioid system engagement are complex and likely multi-factorial. This chapter explores various pathways through which the modulation of the opioid system may influence depression. These include impacts on monoaminergic systems, the regulation of stress and the hypothalamic-pituitary-adrenal axis, the immune system and inflammation, brain-derived neurotrophic factors, neurogenesis and neuroplasticity, social pain and social reward, as well as expectancy and placebo effects. A greater understanding of the diverse mechanisms through which opioid system modulation may improve depressive symptoms could ultimately aid in the development of safe and effective alternative treatments for individuals with difficult-to-treat depression.

Preconception sleep quality moderates the association between preconception hair cortisol levels and mental health in pregnant women

BACKGROUND

Poor sleep quality may elevate cortisol levels and affect prenatal mental health through altered HPA axis functioning. This study aims to examine whether subjective sleep quality during preconception moderates the association between preconception hair cortisol levels and mental health from preconception to pregnancy trimesters.

METHODS

Women from a prospective cohort study completed the Pittsburgh Sleep Quality Index (PSQI), the Edinburgh Postnatal Depression Scale (EPDS), and the State-Trait Anxiety Inventory (STAI) questionnaires during preconception (T0) and at each pregnancy trimesters (T1, T2, and T3). We analyzed 266 of these women who conceived and had fully completed measures at preconception for hair cortisol, sleep quality and either EPDS or STAI-state. Changes in EPDS and STAI-state scores were derived (i.e., T1-T0, T2-T0, T3-T0). Johnson-Neyman technique identified PSQI scores with significant moderation of cortisol on mental health.

RESULTS

After adjusting for potential covariates, there was a significant positive correlation between preconception hair cortisol levels and depressive symptom at the second trimester (r_s (144) = 0.22, p = 0.008), but not the first and third trimesters (all p_s > 0.05). The positive association between preconception hair cortisol and change in depressive symptoms between third trimester and preconception was significant only among women with poor preconception sleep quality (PSQI ≥ 7).

LIMITATIONS

Sleep quality and prenatal mood were derived from self-reported questionnaires, which may be more susceptible to bias.

CONCLUSIONS

The positive association between preconception hair cortisol and change in prenatal depressive symptoms is significant among women who reported poor sleep quality during preconception. Improving preconception sleep quality can potentially mitigate the association between preconception hair cortisol and depressive symptoms during pregnancy.

Intranasal administration of interleukin-4 ameliorates depression-like behavior and biochemical alterations in mouse submitted to the chronic unpredictable mild stress: modulation of neuroinflammation and oxidative stress

Physical and psychological stress modulates the hypothalamic pituitary adrenal (HPA) axis, and the redox and inflammatory systems. Impairments in these systems have been extensively reported in major depression (MD) patients. Therefore, our study aimed to investigate the effects of the intranasal administration of interleukin-4 (IL-4) in mice with depressive-like behavior induced by chronic unpredictable mild stress (CUMS) for 28 days. On the 28th day, mice received IL-4 intranasally (1 ng/mouse) or vehicle (sterile saline), and after 30 min, they were submitted to behavioral tests or euthanasia for blood collection and removal of the adrenal glands, axillary lymph nodes, spleen, thymus, prefrontal cortices (PFC), and hippocampi (HC). A single administration of IL-4 reversed CUMS-induced depression-like behavior in the tail suspension test and splash test, without evoking locomotor changes. IL-4 administration reduced the plasma levels of corticosterone and the increased weight of suprarenal glands in stressed mice. Moreover, IL-4 restored the expression of nuclear factor erythroid 2-related factor 2 (NRF2), nuclear factor kappa B (NF-kB), interleukin 1 beta (IL-1β), IL-4, brain derived neurotrophic factor (BDNF), and indoleamine 2,3-dioxygenase (IDO) in the PFC and HC and modulated oxidative stress markers in these brain structures in stressed mice. Our results showed for the first time the antidepressant-like effect of IL-4 through the modulation of neuroinflammation and oxidative stress. The potential effect of IL-4 administered intranasally arises as an innovative strategy for MD treatment.

Cerebral iron deficiency may induce depression through downregulation of the hippocampal glucocorticoid-glucocorticoid receptor signaling pathway

BACKGROUND

Iron is a trace essential element to sustain the normal neurological function of human. Many researches had reported the involvement of iron deficiency (ID) in neural development and cognitive functions. However, the role of ID in pathogenesis of depression and its underlying mechanism are still unclear.

METHODS

In this study, we first used chronic unpredicted mild stress (CUMS) and iron deprivation mouse models to clarify the pathogenesis role of cerebral ID in depression. Then the role of hippocampal glucocorticoid (GC)-glucocorticoid receptor (GR) pathway in cerebral ID induced depression were elucidated in iron deprivation mice and iron deficiency anemia patients.

RESULTS

Our results revealed that both CUMS and iron deprivation could induce cerebral ID in mice, and combination of iron deprivation and CUMS could accelerate the onset and aggravate the symptoms of depression in mice. In hippocampus, ID led to neuronal injury and neurogenesis decrease, which might be related to downregulation of GC-GR signaling pathway caused GR dysfunction, thereby inhibiting the negative feedback regulation function of hippocampus on hypothalamic-pituitary-adrenal (HPA) axis. Moreover, the overactivity of HPA axis in iron deprivation mice and iron deficiency anemia patients also confirmed GR dysfunction.

LIMITATIONS

Iron deprivation led to food and water intake decrease of mice, which may affect the behavioral test. In addition, we mainly evaluated the role of hippocampal ID in depression, and the number of iron deficiency anemia patients was limited.

CONCLUSIONS

Our results identified that cerebral iron homeostasis was a key factor for maintaining mental stability.

The Wistar Kyoto Rat: A Model of Depression Traits

There is an ongoing debate about the value of animal research in psychiatry with valid lines of reasoning stating the limits of individual animal models compared to human psychiatric illnesses. Human depression is not a homogenous disorder; therefore, one cannot expect a single animal model to reflect depression heterogeneity. This limited review presents arguments that the Wistar Kyoto (WKY) rats show intrinsic depression traits. The phenotypes of WKY do not completely mirror those of human depression but clearly indicate characteristics that are common with it. WKYs present despair- like behavior, passive coping with stress, comorbid anxiety, and enhanced drug use compared to other routinely used inbred or outbred strains of rats. The commonly used tests identifying these phenotypes reflect exploratory, escape-oriented, and withdrawal-like behaviors. The WKYs consistently choose withdrawal or avoidance in novel environments and freezing behaviors in response to a challenge in these tests. The physiological response to a stressful environment is exaggerated in WKYs. Selective breeding generated two WKY substrains that are nearly isogenic but show clear behavioral differences, including that of depression-like behavior. WKY and its substrains may share characteristics of subgroups of depressed individuals with social withdrawal, low energy, weight loss, sleep disturbances, and specific cognitive dysfunction. The genomes of the WKY and WKY substrains contain variations that impact the function of many genes identified in recent human genetic studies of depression. Thus, these strains of rats share characteristics of human depression at both phenotypic and genetic levels, making them a model of depression traits.

The Opioid System in Depression

Opioid receptors are widely distributed throughout the brain and play an essential role in modulating aspects of human mood, reward, and well-being. Accumulating evidence indicates the endogenous opioid system is dysregulated in depression and that pharmacological modulators of mu, delta, and kappa opioid receptors hold potential for the treatment of depression. Here we review animal and clinical data, highlighting evidence to support: dysregulation of the opioid system in depression, evidence for opioidergic modulation of behavioural processes and brain regions associated with depression, and evidence for opioidergic modulation in antidepressant responses. We evaluate clinical trials that have examined the safety and efficacy of opioidergic agents in depression and consider how the opioid system may be involved in the effects of other treatments, including ketamine, that are currently understood to exert antidepressant effects through non-opioidergic actions. Finally, we explore key neurochemical and molecular mechanisms underlying the potential therapeutic effects of opioid system engagement, that together provides a rationale for further investigation into this relevant target in the treatment of depression.

Immune-endocrine biomarkers associated with mental health: A 9-year longitudinal investigation from the Hertfordshire Ageing Study

BACKGROUND

The study of neural-endocrine-immune system interactions has led to substantial advances in our understanding of neuropsychiatric disorders. Growing evidence reveals the pivotal roles of inflammatory cytokines signalling the brain to produce neurochemical, neuroendocrine, and neuroimmune changes which affect mood and behaviour. Ageing is accompanied by the development of low-grade systemic inflammation which may promote changes in the neural systems predisposing to geriatric depression via the hypothalamic-pituitary-adrenal (HPA) axis. The aim of this study was to investigate the longitudinal associations between baseline values and conditional changes (independent of baseline) in immune-endocrine biomarkers and mental health status in a population-based cohort of older adults.

METHODS

Data from 347 subjects (200 men, 147 women) who participated in the Hertfordshire Ageing Study at baseline (1994/5, mean age 67.3 years) and at 9-year follow-up were analysed. Serum samples for analysis of inflammatory and endocrinological measures were collected at baseline and follow-up. At follow-up, depression (Hospital Anxiety and Depression Scale) and mental health (Short Form-36 questionnaire) were assessed. Baseline values and changes in biomarkers in relation to risk of high depression scores (top sex-specific third) and low mental health scores (bottom sex-specific third) were examined using logistic regression.

RESULTS

Lower baseline cortisol was related to greater risk of high depression scores; higher baseline cortisol: dehydroepiandrosterone sulphate ratio (men only) and higher baseline C-reactive protein (CRP) (women only) were related to greater risk of poor mental health scores. In addition, greater decline in cortisol was related to increased risk of high depression scores among men. These relationships were robust (p < 0.05) after controlling for sex, age, BMI, smoking, alcohol consumption and number of systems medicated.

CONCLUSION

This study provides further evidence of the role of the HPA axis and inflammation in older adults with poor mental health. In addition, the findings highlight sex differences where increased inflammation in women and declines in cortisol in men were linked to poorer mental health. Further research is warranted to confirm these findings. This could lead to the search for potential biomarkers to stratify medications as well as developing novel intervention targets to improve mental health at older age.

Sex differences in the association between basal serum cortisol concentrations and cortical thickness

Background

Basal cortisol concentrations vary between men and women. Likewise, previous findings suggest stress-related cortical thickness alterations. Thus, we aimed at elucidating sex differences in the association between serum cortisol concentrations and cortical thickness.

Methods

Data of 2594 participants (55.55% male; mean age = 53.55 years ± 13.17 years) of the general population were used to investigate sex differences in basal serum cortisol concentrations and associations of serum cortisol concentrations with global and regional cortical thickness. The validity of the results was tested by including sex hormone concentrations as a biological and childhood maltreatment and depressive symptoms as a psychological confounder.

Results

Basal serum cortisol concentrations were higher in men than in women (β = -0.158, t₍₂₅₇₅₎ = -6.852, p = 9.056e-12). Sex differences in serum cortisol concentrations were diminished by including serum concentrations of testosterone, estrone, or estradiol in the models. In men but not in women, serum cortisol concentrations were inversely associated with the global cortical thickness (men: β = -0.064, t₍₁₄₁₂₎ = -3.010, p = .003; women: β = -0.016, t₍₁₁₃₁₎ = -0.607, p = .544). Additionally, these effects were observed in eleven cortical regions after adjusting for multiple testing. The associations were independent of childhood maltreatment and depressive symptoms.

Conclusion

Sex differences in serum cortisol concentrations and the association between serum cortisol concentrations and cortical thickness suggest important sex-specific effects of stress on the brain. Future studies should integrate the interaction between the hypothalamic-pituitary-adrenal (HPA) axis and hypothalamic-pituitary-gonadal (HPG) axis in sex-stratified analyses.

Repeated exposure with short-term behavioral stress resolves pre-existing stress-induced depressive-like behavior in mice

Chronic stress induces adaptive changes in the brain via the cumulative action of glucocorticoids, which is associated with mood disorders. Here we show that repeated daily five-minute restraint resolves pre-existing stress-induced depressive-like behavior in mice. Repeated injection of glucocorticoids in low doses mimics the anti-depressive effects of short-term stress. Repeated exposure to short-term stress and injection of glucocorticoids activate neurons in largely overlapping regions of the brain, as shown by c-Fos staining, and reverse distinct stress-induced gene expression profiles. Chemogenetic inhibition of neurons in the prelimbic cortex projecting to the nucleus accumbens, basolateral amygdala, or bed nucleus of the stria terminalis results in anti-depressive effects similarly to short-term stress exposure, while only inhibition of neurons in the prelimbic cortex projecting to the bed nucleus of the stria terminalis rescues defective glucocorticoid release. In summary, we show that short-term stress can reverse adaptively altered stress gains and resolve stress-induced depressive-like behavior.

Does the Interaction between Local and Systemic Inflammation Provide a Link from Psychology and Lifestyle to Tissue Health in Musculoskeletal Conditions?

Musculoskeletal conditions are known to involve biological, psychological, social and, often, lifestyle elements. However, these domains are generally considered in isolation from each other. This siloed approach is unlikely to be adequate to understand the complexity of these conditions and likely explains a major component of the disappointing effects of treatment. This paper presents a hypothesis that aims to provide a foundation to understand the interaction and integration between these domains. We propose a hypothesis that provides a plausible link between psychology and lifestyle factors with tissue level effects (such as connective tissue dysregulation/accumulation) in musculoskeletal conditions that is founded on understanding the molecular basis for interaction between systemic and local inflammation. The hypothesis provides plausible and testable links between mind and body, for which empirical evidence can be found for many aspects. We present this hypothesis from the perspective of connective tissue biology and pathology (fibrosis), the role of inflammation locally (tissue level), and how this inflammation is shaped by systemic inflammation through bidirectional pathways, and various psychological and lifestyle factors via their influence on systemic inflammation. This hypothesis provides a foundation for new consideration of the development and refinement of personalized multidimensional treatments for individuals with musculoskeletal conditions.

Chronic Inflammation Mediates the Association between Cortisol and Hyperglycemia: Findings from the Cross-Sectional Population-Based KORA Age Study

(1) Background: The study aimed to investigate the role of subclinical inflammation on the association between diurnal cortisol patterns and glycaemia in an aged population. (2) Methods: Salivary cortisol, interleukin-6 (IL-6) and glycated haemoglobin (HbA1c) were analysed in a sample of 394 men and 364 women (mean age = 5 ± 6.3, 65–90 years). The ratio of morning after awakening and late-night cortisol was calculated as an indication of diurnal cortisol slope (DCS). Multivariable regression models were run to examine whether IL-6 mediates the relationship between the DCS and glycaemia. The Sobel test and bootstrapping methods were used to quantify the mediation analyses. (3) Results: In comparison to normoglycaemic counterparts (n = 676, 89.2%), an increase in IL-6 concentrations, in individuals with hyperglycaemia (HbA1c ≥ 6.5%) (n = 82, 10.8%) (p = 0.04), was significantly associated with a flatter DCS. The link between flatter DCS and elevated HbA1c level was significant mediated by a heightened IL-6 level. Our results do not suggest reverse-directionality, whereby cortisol did not mediate the association of IL-6 with HbA1c. (4) Conclusions: In our sample, the relation between flatter DCS and hyperglycaemia was partly explained by IL-6 levels. The paradigm of subclinical inflammation-mediated cortisol response on glucose metabolism could have widespread implications for improving our understanding of the pathophysiology of type 2 diabetes mellitus.

Alterations in 'inflammatory' pathways in the rat prefrontal cortex as early biological predictors of the long-term negative consequences of exposure to stress early in life

Early life stress, especially when experienced during the first period of life, affects the brain developmental trajectories leading to an enhanced vulnerability for stress-related psychiatric disorders later in life. Although both clinical and preclinical studies clearly support this association, the biological pathways deregulated by such exposure, and the effects in shaping the neurodevelopmental trajectories, have so far been poorly investigated. By using the prenatal stress (PNS) model, a well-established rat model of early life stress, we performed transcriptomic analyses in the prefrontal cortex of rats exposed or not to PNS and sacrificed at different postnatal days (PNDs 21, 40, 62). We first investigated the long-lasting mechanisms and pathways affected in the PFC. We have decided to focus on the prefrontal cortex because we have previously shown that this brain region is highly sensitive to PNS exposure. We found that adult animals exposed to PNS show alterations in 389 genes, mainly involved in stress and inflammatory signalling. We then wanted to establish whether PNS exposure could also affect the neurodevelopmental trajectories in order to identify the most critical temporal window. We found that PNS rats show the most significant changes during adolescence (between PND 40 versus PND 21), with alterations of several pathways related to stress, inflammation and metabolism, which were maintained until adulthood.

Are the thyroid and adrenal system alterations linked in depression?

BACKGROUND

Disturbances in the hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-adrenal (HPA) axes have been frequently found in major depression. Given that glucocorticoids may inhibit thyrotropin (TSH) and thyrotropin-releasing hormone (TRH) secretion, it has been hypothesized that hypercortisolemia could lead to HPT axis abnormalities. So far, data on interactions between the HPA and HPT axes in depression remain inconclusive.

METHODS

In order to investigate this issue, we examined circadian rhythms of serum TSH and cortisol (sampled at 4 -hly intervals throughout a 24 -h span), TSH responses to 0800 h and 2300 h protirelin (TRH) tests and cortisol response to dexamethasone suppression test (DST) in 145 unmedicated inpatients meeting DSM-IV criteria for major depressive disorder (MDDs) and 25 healthy hospitalized control subjects (HCs).

RESULTS

The secretion of TSH and cortisol exhibited a significant circadian rhythm both in HCs and MDDs. However, compared to HCs, MDDs showed: 1) reduced TSH mesor and amplitude values; 2) blunted 2300 h-ΔTSH and ΔΔTSH values (i.e. differences between 2300 h and 0800 h TRH-TSH responses); and 3) increased cortisol mesor and post-DST cortisol values. DST nonsuppresssors (n = 40, 27 %) showed higher cortisol mesor than DST suppressors (n = 105, 73 %). There was no difference between DST suppressors and nonsuppressors in their TSH circadian parameters and TRH-TSH responses. In addition, cortisol values (circadian and post-DST) were not related to TRH test responses.

CONCLUSION

Our results do not confirm a key role for hypercortisolemia in the HPT axis dysregulation in depression.

Hair cortisol in patients with a depressive episode treated with electroconvulsive therapy

BACKGROUND

There is substantial evidence showing changes in hypothalamic pituitary adrenal (HPA)-axis activity in patients with major depressive disorder (MDD). Also, there seem to be differences in HPA-axis functioning between MDD subgroups. It is however unclear whether hair cortisol concentrations (HCC), which are a stable marker of long-term cortisol levels, are suitable as a biomarker for identifying subgroups in MDD.

METHODS

We were able to attain valid HCC from a scalp hair sample of sixty-two patients with a major depressive episode right before electroconvulsive therapy (ECT). HCC were our main biological outcome measure. We created subgroups using depression severity as defined by the Hamilton Depression Rating Scale, the presence/absence of psychotic symptoms, the presence of melancholia as defined by the CORE and catatonia as defined by the Bush-Francis Catatonia Rating Scale.

RESULTS

Our analyses of the total group showed a median HCC of 4.4 pg/mg. We found patients with catatonia (N = 10) to have substantially higher median HCC (8.3 pg/mg) than patients without catatonia (3.8 pg/mg). Although presence of melancholia and depression severity were not significantly associated with HCC, more severe psychomotor agitation was associated with higher HCC. Pre-treatment HCC was not associated with ECT outcome.

STRENGTHS AND LIMITATIONS

A complicating factor in interpretation of our results was the large variability in HCC. This could be related to potential confounders such as cardiometabolic and other comorbidities, that were however addressed to the extent possible.

CONCLUSIONS

HCC is a potential biomarker for MDD patients with severe agitation and/or catatonia. CLINICALTRIALS.GOV: Identifier: NCT02562846.

Cortisol and DHEA-S levels in pregnant women with severe anxiety

BACKGROUND

A complex interaction between cortisol and dehydroepiandrosterone-sulphate (DHEA-S) is crucial in the stress system balance; several studies have reported increased cortisol levels during chronic stress and a weak counter-regulation by DHEA-S. During pregnancy, scarce information about this system is available, although cortisol and DHEA-S play an important role in the initiation and acceleration of labor. We conducted the present study in order to determine both cortisol and DHEA-S levels during the last trimester of pregnancy in patients exhibiting severe anxiety.

METHODS

Pregnant women during the 3rd trimester of pregnancy were evaluated by using the self-reported version of the Hamilton Anxiety Rating Scale (HARS). According to the scores obtained from the psychometric scale, participants were divided into two groups: 1) patients exhibiting a cutoff score > 15 were considered with severe anxiety (ANX) (n = 101), and control pregnant subjects (CTRL) (n = 44) with a cutoff score < 5. Morning cortisol, DHEA-S and Cortisol/DHEA-S index were measured in all participants. Comparisons between groups were performed; additionally, correlations between clinical variables, biochemical data and HARS were calculated.

RESULTS

Cortisol levels were significantly higher in the ANX group (p < 0.001), whereas those of DHEA-S were significantly lower in the same group (p < 0.01) when compared to healthy pregnant subjects. An increased cortisol/DHEA-S index was observed in the ANX group (p < 0.05). A significant association between cortisol and HARS scores (p = 0.03), was observed even after adjusting by gestational weeks (p = 0.004).

CONCLUSIONS

Our data support that the cortisol/DHEA-S index is higher in pregnant women with high anxiety levels as compared with healthy pregnant women.

State-of-the-Art: Inflammatory and Metabolic Markers in Mood Disorders

Mounting evidence highlights the involvement of inflammatory/immune systems and their relationships with neurotransmitters and different metabolic processes in mood disorders. Nevertheless, there is a general agreement that available findings are still inconclusive. Therefore, further investigations are required, aimed at deepening the role of possible alterations of biomarkers in the pathophysiology of mood disorders that might lead to more focused and tailored treatments. The present study is a comprehensive review on these topics that seem to represent intriguing avenues for the development of real innovative therapeutic strategies of mood disorders.

Sex differences in hypothalamic-pituitary-adrenal axis regulation after chronic unpredictable stress

INTRODUCTION

Exposure to stress, mediated through the hypothalamic-pituitary-adrenal (HPA) axis, elicits sex differences in endocrine, neurological, and behavioral responses. However, the sex-specific factors that confer resilience or vulnerability to stress and stress-associated psychiatric disorders remain largely unknown. The evident sex differences in stress-related disease prevalence suggest the underlying differences in the neurobiological underpinnings of HPA axis regulation.

METHOD

Here, we used a chronic unpredictable stress (CUS) model to investigate the behavioral and biochemical responses of the HPA axis in C57BL/6 mice. Animals were tested in the open field and forced swim test to examine anxiety-like and depressive-like behaviors. Plasma corticosterone levels were measured after behavior and CUS, and glucocorticoid receptor (GR) expression and cytosolic and nuclear fractions of binding protein FKBP51 expression were taken to measure function and regulation of the stress response.

RESULTS

Our results indicate increased depressive-like behavior in males and females which correlated with increased corticosterone levels following CUS. However, females displayed more anxiety-like behaviors with and without CUS. Interestingly, we found trends toward dysregulation of GR protein expression in CUS females, and an increase in the GR inhibitory protein, FKBP51, in the cytosol of CUS males but not females.

CONCLUSION

These results suggest biochemical alterations to the HPA axis regulation which may elicit a glucocorticoid resistance in females after chronic stress and may contribute to the sex-biased vulnerability to stress-related psychiatric disorders.

The intersections of stress, anxiety and epilepsy

Stress is ubiquitous in chronic medical conditions; however, the connections to psychiatric and neurologic conditions are not always clearly established. Epilepsy is a unique illness that is intimately intertwined with stress and anxiety not only as a result of the disease process but also as a cause of disease exacerbation. Anxiety and depression also involve stress management and often overlap with epilepsy. Anxiety symptoms themselves may be present as intrinsic aspects of seizure phenomena, either during the events or closely related to them. The pathways of stress and anxiety involve the hypothalamic pituitary adrenal (HPA) axis and explain at least in part how stress may lead to worsening seizure control. Ultimately, the study of stress, anxiety, and epilepsy offers insight into mind and body connections, and furthers understanding of neuropsychiatric illness.

The hypothalamic-pituitary-adrenal axis as a substrate for stress resilience: Interactions with the circadian clock

Stress, primarily processed via the hypothalamic-pituitary-adrenal (HPA) axis, engages biological pathways throughout the brain and body which promote adaptation and survival to changing environmental demands. Adaptation to environmental challenges is compromised when these pathways are no longer functioning optimally. The physiological and behavioral mechanisms through which HPA axis function influences stress adaptation and resilience are not fully elucidated. Our understanding of stress biology and disease must take into account the complex interactions between the endocrine system, neural circuits, and behavioral coping strategies. In addition, further consideration must be taken concerning influences of other aspects of physiology, including the circadian clock which is critical for regulation of daily changes in HPA activity. While adding a layer of complexity, it also offers targets for intervention. Understanding the role of HPA function in mediating these diverse biological responses will lead to important insights about how to bolster successful stress adaptation and promote stress resilience.

Novel Treatment Targets Based on Insights in the Etiology of Depression: Role of IL-6 Trans-Signaling and Stress-Induced Elevation of Glutamate and ATP

Inflammation and psychological stress are risk factors for major depression and suicide. Both increase central glutamate levels and activate the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Both factors also affect the function of the chloride transporters, Na-K-Cl-cotransporter-1 (NKCC1) and K-Cl-cotransporter-2 (KCC2), and provoke interleukin-6 (IL-6) trans-signaling. This leads to measurable increases in circulating corticosteroids, catecholamines, anxiety, somatic and psychological symptoms, and a decline in cognitive functions. Recognition of the sequence of pathological events allows the prediction of novel targets for therapeutic intervention. Amongst others, these include blockade of the big-K potassium channel, blockade of the P2X4 channel, TYK2-kinase inhibition, noradrenaline α2B-receptor antagonism, nicotinic α7-receptor stimulation, and the Sgp130Fc antibody. A better understanding of downstream processes evoked by inflammation and stress also allows suggestions for tentatively better biomarkers (e.g., SERPINA3N, MARCKS, or ¹³C-tryptophan metabolism).

Increased Serum Levels of Cortisol and Inflammatory Cytokines in People With Depression

This cross-sectional study aimed at measuring the correlation and association between serum levels of cortisol, inflammatory cytokines, and depression and to measure the detection accuracy of serum levels of cortisol in serum samples. In total, 89 male participants were recruited into this study from June 15, 2017, to September 31, 2017. The Hamilton Depression Rating Scale, Beck Anxiety Inventory, and Pittsburgh Sleep Quality Index were used to investigate the mental health status of the participants. Serum concentrations of cortisol and inflammatory cytokines were determined. The serum cortisol concentration, anxiety level, and sleep quality were included in the final logistic regression model. Serum cortisol was able to accurately distinguish between patients with depression and those without depression. There was a significant positive correlation between serum cortisol levels and Hamilton Depression Rating Scale scores.

Neuroactive Steroids and GABAergic Involvement in the Neuroendocrine Dysfunction Associated With Major Depressive Disorder and Postpartum Depression

Stress and previous adverse life events are well-established risk factors for depression. Further, neuroendocrine disruptions are associated with both major depressive disorder (MDD) and postpartum depression (PPD). However, the mechanisms whereby stress contributes to the underlying neurobiology of depression remains poorly understood. The hypothalamic-pituitary-adrenal (HPA) axis, which mediates the body's neuroendocrine response to stress, is tightly controlled by GABAergic signaling and there is accumulating evidence that GABAergic dysfunction contributes to the impact of stress on depression. GABAergic signaling plays a critical role in the neurobiological effects of stress, not only by tightly controlling the activity of the HPA axis, but also mediating stress effects in stress-related brain regions. Deficits in neuroactive steroids and neurosteroids, some of which are positive allosteric modulators of GABA_A receptors (GABA_ARs), such as allopregnanolone and THDOC, have also been implicated in MDD and PPD, further supporting a role for GABAergic signaling in depression. Alterations in neurosteroid levels and GABAergic signaling are implicated as potential contributing factors to neuroendocrine dysfunction and vulnerability to MDD and PPD. Further, potential novel treatment strategies targeting these proposed underlying neurobiological mechanisms are discussed. The evidence summarized in the current review supports the notion that MDD and PPD are stress-related psychiatric disorders involving neurosteroids and GABAergic dysfunction.

Molecular aspects of depression: A review from neurobiology to treatment

Major depressive disorder (MDD), also known as unipolar depression, is one of the leading causes of disability and disease worldwide. The signs and symptoms are low self‑esteem, anhedonia, feeling of worthlessness, sense of rejection and guilt, suicidal thoughts, among others. This review focuses on studies with molecular-based approaches involving MDD to obtain an integrated, more detailed and comprehensive view of the brain changes produced by this disorder and its treatment and how the Central Nervous System (CNS) produces neuroplasticity to orchestrate adaptive defensive behaviors. This article integrates affective neuroscience, psychopharmacology, neuroanatomy and molecular biology data. In addition, there are two problems with current MDD treatments, namely: 1) Low rates of responsiveness to antidepressants and too slow onset of therapeutic effect; 2) Increased stress vulnerability and autonomy, which reduces the responses of currently available treatments. In the present review, we encourage the prospection of new bioactive agents for the development of treatments with post-transduction mechanisms, neurogenesis and pharmacogenetics inducers that bring greater benefits, with reduced risks and maximized access to patients, stimulating the field of research on mood disorders in order to use the potential of preclinical studies. For this purpose, improved animal models that incorporate the molecular and anatomical tools currently available can be applied. Besides, we encourage the study of drugs that do not present "classical application" as antidepressants, (e.g., the dissociative anesthetic ketamine and dextromethorphan) and drugs that have dual action mechanisms since they represent potential targets for novel drug development more useful for the treatment of MDD.

Tactile Stimulation on Adulthood Modifies the HPA Axis, Neurotrophic Factors, and GFAP Signaling Reverting Depression-Like Behavior in Female Rats

Depression is a common psychiatric disease which pharmacological treatment relieves symptoms, but still far from ideal. Tactile stimulation (TS) has shown beneficial influences in neuropsychiatric disorders, but the mechanism of action is not clear. Here, we evaluated the TS influence when applied on adult female rats previously exposed to a reserpine-induced depression-like animal model. Immediately after reserpine model (1 mg/kg/mL, 1×/day, for 3 days), female Wistar rats were submitted to TS (15 min, 3×/day, for 8 days) or not (unhandled). Imipramine (10 mg/kg/mL) was used as positive control. After behavioral assessments, animals were euthanized to collect plasma and prefrontal cortex (PFC). Behavioral observations in the forced swimming test, splash test, and sucrose preference confirmed the reserpine-induced depression-like behavior, which was reversed by TS. Our findings showed that reserpine increased plasma levels of adrenocorticotropic hormone and corticosterone, decreased brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B, and increased proBDNF immunoreactivity in the PFC, which were also reversed by TS. Moreover, TS reestablished glial fibrillary acidic protein and glucocorticoid receptor levels, decreased by reserpine in PFC, while glial cell line-derived neurotrophic factor was increased by TS per se. Our outcomes are showing that TS applied in adulthood exerts a beneficial influence in depression-like behaviors, modulating the HPA axis and regulating neurotrophic factors more effectively than imipramine. Based on this, our proposal is that TS, in the long term, could be considered a new therapeutic strategy for neuropsychiatric disorders improvement in adult life, which may represent an interesting contribution to conventional pharmacological treatment.

Influence of pharmacological and epigenetic factors to suppress neurotrophic factors and enhance neural plasticity in stress and mood disorders

Stress-induced major depression and mood disorders are characterized by behavioural abnormalities and psychiatric illness, leading to disability and immature mortality worldwide. Neurobiological mechanisms of stress and mood disorders are discussed considering recent findings, and challenges to enhance pharmacological effects of antidepressant, and mood stabilizers. Pharmacological enhancement of ketamine and scopolamine regulates depression at the molecular level, increasing synaptic plasticity in prefrontal regions. Blood-derived neurotrophic factors facilitate mood-deficit symptoms. Epigenetic factors maintain stress-resilience in hippocampal region. Regulation of neurotrophic factors blockades stress, and enhances neuronal survival though it paralyzes limbic regions. Molecular agents and neurotrophic factors also control behavioral and synaptic plasticity in addiction and stress disorders. Future research on neuronal dynamics and cellular actions can be directed to obtain the etiology of synaptic dysregulation in mood disorder and stress. For the first time, the current review contributes to the literature of synaptic plasticity representing the role of epigenetic mechanisms and glucocorticoid receptors to predict depression and anxiety in clinical conditions.

Peripheral Biomarkers of Inflammation in Depression: Evidence from Animal Models and Clinical Studies

Depression is a highly prevalent psychiatric condition, with over 300 million sufferers, and is an important comorbidity for other conditions, like cardiovascular disorders or diabetes. Therapy is largely based on psychotherapy and/or pharmacological intervention, particularly aimed at altering neurotransmitter levels in the central nervous system, but inadequate response to treatment remains a significant clinical problem. Herein, evidence supporting a molecular link between inflammation and depression will be discussed, particularly the increased prevalence of depression in chronic inflammatory diseases and the evidence on the use of anti-inflammatory drugs to treat depression. Moreover, the potential for the levels of peripheral inflammatory molecules to act as depression biomarkers, in the diagnosis and monitoring of depression will be examined, considering clinical- and animal model-based evidence.

Prefrontal cortical trkB, glucocorticoids, and their interactions in stress and developmental contexts

The tropomyosin/tyrosine receptor kinase B (trkB) and glucocorticoid receptor (GR) regulate neuron structure and function and the hormonal stress response. Meanwhile, disruption of trkB and GR activity (e.g., by chronic stress) can perturb neuronal morphology in cortico-limbic regions implicated in stressor-related illnesses like depression. Further, several of the short- and long-term neurobehavioral consequences of stress depend on the developmental timing and context of stressor exposure. We review how the levels and activities of trkB and GR in the prefrontal cortex (PFC) change during development, interact, are modulated by stress, and are implicated in depression. We review evidence that trkB- and GR-mediated signaling events impact the density and morphology of dendritic spines, the primary sites of excitatory synapses in the brain, highlighting effects in adolescents when possible. Finally, we review the role of neurotrophin and glucocorticoid systems in stress-related metaplasticity. We argue that better understanding the long-term effects of developmental stressors on PFC trkB, GR, and related factors may yield insights into risk for chronic, remitting depression and related neuropsychiatric illnesses.

α-Tocopherol Ameliorates Redox Equilibrium and Reduces Inflammatory Response Caused by Chronic Variable Stress

Chronic exposure to stress factors contributes to the development of depression by generating excess of reactive oxygen species which leads to oxidative stress and inflammatory processes. The aim of the study was to assess the potential protective properties of α-tocopherol supplementation on the rats exposed to chronic variable stress (CVS). Male Wistar rats (50-55 days old, weighing 200-250 g) were divided into three groups (n=10): control, stressed, and stressed and receiving (+)-α-tocopherol solution in a dose of 100 mg/kg/day. Rats in the stressed groups were exposed to CVS for 40 days. Markers of redox disorders (glutathione reduced and oxidized levels, GSH/GSSG ratio, glutathione peroxidase, glutathione reductase activities, total antioxidant status, and lipid peroxidation) and inflammatory response (IL-1β, IL6, and TNF-α) were determined in the blood. Additionally, molecular biomarkers of depression (expression of Fkbp5 and Tph2) were studied in hippocampus. The biochemical analysis was inconclusive about the presence of oxidative stress in the blood of rats exposed to CVS. However, changes in all parameters suggest presence of redox equilibrium disorders. Similarly, activation of inflammatory processes was observed as a result of CVS. Molecular effects of environmental stress in hippocampus were also observed. Generally, α-tocopherol ameliorated redox equilibrium disorders, tempered inflammatory response, and protected from changes in determined molecular markers of depression.

Child sex moderates the relationship between cortisol stress reactivity and symptoms over time

BACKGROUND

Past work suggests that individual differences in stress reactivity have implications for the development of psychopathology; in particular, females' stress reactivity appears more closely tied to internalizing symptoms than males' reactivity. Conversely, males who are under-reactive to threat may be at risk for externalizing problems. However, little is known about when such differences may emerge, although this knowledge could have implications for early prevention.

METHODS

Cortisol reactivity to a laboratory stressor was assessed in 409 three-year-old children (201 boys), along with parent-reported children's internalizing (anxiety and depression) and externalizing (oppositional-defiant and attention problems and hyperactivity) symptoms. Parent-reported symptoms were re-collected at child ages 5 (N = 379) and 8 (N = 364). Multilevel modelling was used to investigate whether the relationship between cortisol reactivity and symptoms differed between boys and girls over time.

RESULTS

Girls with lower cortisol reactivity showed a negative association between depressive symptoms and time, while girls with higher reactivity showed no such association. No interaction between sex and cortisol reactivity was found for anxious symptoms. Boys with higher cortisol reactivity showed a negative association between symptoms and time, while boys with lower cortisol reactivity showed no such association. Time and ADHD symptoms were unrelated for boys, regardless of their cortisol reactivity.

CONCLUSIONS

Findings suggest that the implications of stress reactivity indexed via cortisol vary for boys and girls, as well as for different symptom manifestations.

Regulators of glucocorticoid receptor function in an animal model of depression and obesity

Obesity is a disease that often co-occurs with depression, and some evidence indicates that chronic stress in the perinatal period, in association with overactive glucocorticoids, can cause permanent changes that increase the risk of the development of both depression and obesity later in life. However, the mechanism responsible for the overly potent action of glucocorticoids in both depression and obesity is not known. The aim of the present study was to determine the expression of glucocorticoid receptors (GRs) and mineralocorticoid receptors (MRs) and the factors that affect GR function (FKBP51, Bag-1 and HSP70) in a prenatal stress animal model of depression, a model of obesity and a model of both depression and obesity. Prenatal stress but not high-fat diet (HFD) was found to decrease the GR concentration in the frontal cortex. The level of the Bag-1M (46 kDa) isoform was also decreased in this structure but only in prenatal-stressed animals that did not show depression-like behaviour in the Porsolt test and were fed the standard diet (STD). In the model of depression employed here, decreases in MR expression and GR co-chaperone (FKBP51) levels in the hippocampus were also observed, and HFD intensified the prenatal stress-induced changes in MR expression. The obtained results indicated that prenatal stress affected the expression of GRs, MRs and their co-chaperones in the brain, but its effects were different in the frontal cortex and hippocampus. The decrease in MR density in the hippocampus and increased plasma insulin level seemed to be the most significant changes observed in the model of the co-occurrence of depression and obesity, which could limit the neuroprotective effects associated with the activation of MR and be a marker of peripheral insulin resistance, respectively. This article is protected by copyright. All rights reserved.

Glia- and tissue-specific changes in the Kynurenine Pathway after treatment of mice with lipopolysaccharide and dexamethasone

Behavioral symptoms associated with mood disorders have been intimately linked with immunological and psychological stress. Induction of immune and stress pathways is accompanied by increased tryptophan entry into the Kynurenine (Kyn) Pathway as governed by the rate-limiting enzymes indoleamine/tryptophan 2,3-dioxygenases (DO's: Ido1, Ido2, Tdo2). Indeed, elevated DO expression is associated with inflammation- and stress-related depression symptoms. Here we examined central (brain, astrocyte and microglia) and peripheral (lung, liver and spleen) DO expression in mice treated intraperitoneally with lipopolysaccharide (LPS) and dexamethasone (DEX) to model the response of the Kyn Pathway to inflammation and glucocorticoids. LPS-induced expression of cytokines in peripheral tissues was attenuated by DEX, confirming inflammatory and anti-inflammatory responses, respectively. Increased Kyn levels following LPS and DEX administration verified Kyn Pathway activation. Expression of multiple mRNA isoforms for each DO, which we have shown to be differentially utilized and regulated, were quantified including reference/full-length (FL) and variant (v) transcripts. LPS increased Ido1-FL in brain (∼1000-fold), a response paralleled by increased expression in both astrocytes and microglia. Central Ido1-FL was not changed by DEX; however, LPS-induced Ido1-FL was decreased by DEX in peripheral tissues. In contrast, DEX increased Ido1-v1 expression by astrocytes and microglia, but not peripheral tissues. In comparison, brain Ido2 was minimally induced by LPS or DEX. Uniquely, Ido2-v6 was LPS- and DEX-inducible in astrocytes, suggesting a unique role for astrocytes in response to inflammation and glucocorticoids. Only DEX increased central Tdo2 expression; however, peripheral Tdo2 was upregulated by either LPS or DEX. In summary, specific DO isoforms are increased by LPS and DEX, but LPS-dependent Ido1 and Ido2 induction are attenuated by DEX only in the periphery indicating that elevated DO expression and Kyn production within the brain can occur independent of the periphery. These findings demonstrate a plausible interaction between immune activation and glucocorticoids associated with depression.

Saikosaponin D relieves unpredictable chronic mild stress induced depressive-like behavior in rats: involvement of HPA axis and hippocampal neurogenesis

RATIONALE

Saikosaponin D (SSD), a major bioactive component isolated from Radix Bupleuri, has been reported to exert neuroprotective properties.

OBJECTIVES

The present study was designed to investigate the anti-depressant-like effects and the potential mechanisms of SSD.

METHODS

Behavioural tests including sucrose preference test (SPT), open field test (OFT) and forced swim test (FST) were performed to study the antidepressant-like effects of SSD. In addition, we examined corticosterone and glucocorticoid receptor (GR) levels to evaluate hypothalamic-pituitary-adrenal (HPA) axis function. Furthermore, hippocampal neurogenesis was assessed by testing doublecortin (DCX) levels, and neurotrophic molecule levels were also investigated in the hippocampus of rats.

RESULTS

We found that unpredictable chronic mild stress (UCMS) rats displayed lost body weight, decreased sucrose consumption in SPT, reduced locomotive activity in OFT, and increased immobility time in FST. Chronic treatment with SSD (0.75, 1.50 mg/kg) remarkably ameliorated the behavioral deficiency induced by UCMS procedure. SSD administration downregulated elevated serum corticosterone levels, as well as alleviated the suppression of GR expression and nuclear translocation caused by UCMS, suggesting that SSD is able to remit the dysfunction of HPA axis. In addition, Western blot and immunohistochemistry analysis showed that SSD treatment significantly increased the generation of neurons in the hippocampus of UCMS rats indicated by elevated DCX levels. Moreover, hippocampal neurotrophic molecule levels of UCMS rats such as phosphorylated cAMP response element binding protein (p-CREB) and brain-derived neurotrophic factor (BDNF) were raised after SSD treatment.

CONCLUSIONS

Together, Our results suggest that SSD opposed UCMS-induced depressive behaviors in rats, which was mediated, partially, by the enhancement of HPA axis function and consolidation of hippocampal neurogenesis.

Differential effects of imipramine and CORT118335 (Glucocorticoid receptor modulator/mineralocorticoid receptor antagonist) on brain-endocrine stress responses and depression-like behavior in female rats

Depression is commonly associated with hypothalamic-pituitary adrenal (HPA) axis dysfunction that primarily manifests as aberrant glucocorticoid secretion. Glucocorticoids act on Type I mineralocorticoid (MR) and Type II glucocorticoid receptors (GR) to modulate mood and endocrine responses. Successful antidepressant treatment normalizes HPA axis function, in part due to modulatory effects on MR and GR in cortico-limbic structures. Although women are twice as likely to suffer from depression, little is known about how antidepressants modulate brain, endocrine, and behavioral stress responses in females. Here, we assessed the impact of CORT118335 (GR modulator/MR antagonist) and imipramine (tricyclic antidepressant) on neuroendocrine and behavioral responses to restraint or forced swim stress (FST) in female rats (n=10-12/group). Increased immobility CORT118335 in the FST is purported to reflect passive coping or depression-like behavior. CORT118335 dampened adrenocorticotropic hormone (ACTH) and corticosterone responses to the FST, but did not affect immobility. Imipramine suppressed ACTH, but had minimal effects on corticosterone responses to FST. Despite these marginal effects, imipramine decreased immobility, suggesting antidepressant efficacy. In an effort to link brain-endocrine responses with behavior, c-Fos was assessed in HPA axis and mood modulatory regions in response to the FST. CORT118335 upregulated c-Fos expression in the paraventricular nucleus of the hypothalamus. Imipramine decreased c-Fos in the basolateral amygdala and hippocampus (CA1 and CA3), but increased c-Fos in the central amygdala. These data suggest the antidepressant-like (e.g., active coping) properties of imipramine may be due to widespread effects on cortico-limbic circuits that regulate emotional and cognitive processes.

A mixed glucocorticoid/mineralocorticoid receptor modulator dampens endocrine and hippocampal stress responsivity in male rats

Aberrant glucocorticoid secretion is implicated in the pathophysiology of stress-related disorders (i.e., depression, anxiety). Glucocorticoids exert biological effects via mineralocorticoid (MR) and glucocorticoid (GR) receptors. Previous data from our laboratory indicate that GR antagonism/modulation (i.e., mifepristone, CORT 108297) regulate endocrine, behavioral, and central stress responses. Because of the dynamic interplay between MR and GR on HPA axis regulation and emotionality, compounds targeting both receptors are of interest for stress-related pathology. We investigated the effects of CORT 118335 (a dual selective GR modulator/MR antagonist) on endocrine, behavioral, and central (c-Fos) stress responses in male rats. Rats were treated for five days with CORT 118335, imipramine (positive control), or vehicle and exposed to restraint or forced swim stress (FST). CORT 118335 dampened corticosterone responses to both stressors, without a concomitant antidepressant-like effect in the FST. Imipramine decreased corticosterone responses to restraint stress; however, the antidepressant-like effect of imipramine in the FST was independent of circulating glucocorticoids. These findings indicate dissociation between endocrine and behavioral stress responses in the FST. CORT 118335 decreased c-Fos expression only in the CA1 division of the hippocampus. Imipramine decreased c-Fos expression in the basolateral amygdala and CA1 and CA3 divisions of the hippocampus. Overall, the data indicate differential effects of CORT 118335 and imipramine on stress-induced neuronal activity in various brain regions. The data also highlight a complex relationship between neuronal activation in stress and mood regulatory brain regions and the ensuing impact on endocrine and behavioral stress responses.

Epigenetic programming of the neuroendocrine stress response by adult life stress

The hypothalamic-pituitary-adrenal (HPA) axis is critically involved in the neuroendocrine regulation of stress adaptation, and the restoration of homeostasis following stress exposure. Dysregulation of this axis is associated with stress-related pathologies like major depressive disorder, post-traumatic stress disorder, panic disorder and chronic anxiety. It has long been understood that stress during early life can have a significant lasting influence on the development of the neuroendocrine system and its neural regulators, partially by modifying epigenetic regulation of gene expression, with implications for health and well-being in later life. Evidence is accumulating that epigenetic plasticity also extends to adulthood, proposing it as a mechanism by which psychological trauma later in life can long-lastingly affect HPA axis function, brain plasticity, neuronal function and behavioural adaptation to neuropsychological stress. Further corroborating this claim is the phenomenon that these epigenetic changes correlate with the behavioural consequences of trauma exposure. Thereby, epigenetic modifications provide a putative molecular mechanism by which the behavioural phenotype and transcriptional/translational potential of genes involved in HPA axis regulation can change drastically in response to environmental challenges, and appear an important target for treatment of stress-related disorders. However, improved insight is required to increase their therapeutic (drug) potential. Here, we provide an overview of the growing body of literature describing the epigenetic modulation of the (primarily neuroendocrine) stress response as a consequence of adult life stress and interpret the implications for, and the challenges involved in applying this knowledge to, the identification and treatment of stress-related psychiatric disorders.

Neuronal substrates underlying stress resilience and susceptibility in rats

Background

Stress and stressful life events have repeatedly been shown as causally related to depression. The Chronic Mild Stress rat model is a valid model of stress-induced depression. Like humans, rats display great heterogeneity in their response to stress and adversity. Hence some individuals are stress-sensitive and prone to develop depression-like behaviour in response to modest stressors, while others are stress-resilient and remain essentially symptom free.

Objectives

Compared to the large body of research, which describes stress-induced maladaptive neurobiological changes, relatively little attention has been devoted to understand resiliency to stress. The aim of the present study was to identify changes in neuronal activity, associated with stress-resilient and stress-susceptible chronic mild stress endophenotypes, by examining c-Fos expression in 13 different brain areas. Changes in c-Fos expression have been reported as associated to stressful conditions.

Methods

Stress-induced modulation of neuronal activation patterns in response to the chronic mild stress paradigm was mapped using the immediate early gene expression c-Fos as a marker. Quantification of the c-Fos-like immunoreactivity responses was done by semi-automated profile counting procedures and design-based stereology.

Results

Exposure to chronic mild stress significantly altered c-Fos expression in a total of 6 out of 13 investigated areas. Chronic mild stress was found to suppress the c-Fos response within the magnocellular ventral lateral geniculate nucleus of both stress subgroups. In the the lateral and ventral orbital cortices of stress-resilient rats, the c-Fos like immunoreactivity response was also repressed by stress exposure. On the contrary the c-Fos response within the amygdala, medial habenula, and infralimbic cortex was increased selectively for the stress-susceptible rats.

Conclusions

The study was initiated to characterize neuronal substrates associated with stress-coping mechanisms. Six areas, all of which represents limbic structures, were found to be sensitive to stress exposure. The effects within these areas associate to the hedonic status of the rats. Hence, these areas might be associated to stress-coping mechanisms underlying the chronic mild stress induced segregation into stress-susceptible and stress-resilient endophenotypes.

Impaired Spinal Glucocorticoid Receptor Signaling Contributes to the Attenuating Effect of Depression on Mechanical Allodynia and Thermal Hyperalgesia in Rats with Neuropathic Pain

Although depression-induced altered pain perception has been described in several laboratory and clinical studies, its neurobiological mechanism in the central nervous system (CNS), particularly in the spinal dorsal horn, remains unclear. Therefore, in this study, we aimed to clarify whether nociceptive sensitivity of neuropathic pain is altered in the olfactory bulbectomy (OB) model of depression and whether glucocorticoid receptor (GR), which is involved in the etio-pathologic mechanisms of both major depression and neuropathic pain, contributes to these processes in the spinal dorsal horn of male Sprague-Dawley rats. The results showed that mechanical allodynia and thermal hyperalgesia induced by spinal nerve ligation (SNL) were attenuated in OB-SNL rats with decreased spinal GR expression and nuclear translocation, whereas non-olfactory bulbectomy (NOB)-SNL rats showed increased spinal GR nuclear translocation. In addition, decreased GR nuclear translocation with normal mechanical nociception and hypoalgesia of thermal nociception were observed in OB-Sham rats. Intrathecal injection (i.t.) of GR agonist dexamethasone (Dex; 4 μg/rat/day for 1 week) eliminated the attenuating effect of depression on nociceptive hypersensitivity in OB-SNL rats and aggravated neuropathic pain in NOB-SNL rats, which was associated with the up-regulation of brain-derived neurotrophic factor (BDNF), TrkB and NR2B expression in the spinal dorsal horn. The present study shows that depression attenuates the mechanical allodynia and thermal hyperalgesia of neuropathic pain and suggests that altered spinal GR-BDNF-TrkB signaling may be one of the reasons for depression-induced hypoalgesia.

Modulation of the Hypothalamic-Pituitary-Adrenal Axis by Early Life Stress Exposure

Exposure to stress during critical periods in development can have severe long-term consequences, increasing overall risk on psychopathology. One of the key stress response systems mediating these long-term effects of stress is the hypothalamic-pituitary-adrenal (HPA) axis; a cascade of central and peripheral events resulting in the release of corticosteroids from the adrenal glands. Activation of the HPA-axis affects brain functioning to ensure a proper behavioral response to the stressor, but stress-induced (mal)adaptation of the HPA-axis' functional maturation may provide a mechanistic basis for the altered stress susceptibility later in life. Development of the HPA-axis and the brain regions involved in its regulation starts prenatally and continues after birth, and is protected by several mechanisms preventing corticosteroid over-exposure to the maturing brain. Nevertheless, early life stress (ELS) exposure has been reported to have numerous consequences on HPA-axis function in adulthood, affecting both its basal and stress-induced activity. According to the match/mismatch theory, encountering ELS prepares an organism for similar ("matching") adversities during adulthood, while a mismatching environment results in an increased susceptibility to psychopathology, indicating that ELS can exert either beneficial or disadvantageous effects depending on the environmental context. Here, we review studies investigating the mechanistic underpinnings of the ELS-induced alterations in the structural and functional development of the HPA-axis and its key external regulators (amygdala, hippocampus, and prefrontal cortex). The effects of ELS appear highly dependent on the developmental time window affected, the sex of the offspring, and the developmental stage at which effects are assessed. Albeit by distinct mechanisms, ELS induced by prenatal stressors, maternal separation, or the limited nesting model inducing fragmented maternal care, typically results in HPA-axis hyper-reactivity in adulthood, as also found in major depression. This hyper-activity is related to increased corticotrophin-releasing hormone signaling and impaired glucocorticoid receptor-mediated negative feedback. In contrast, initial evidence for HPA-axis hypo-reactivity is observed for early social deprivation, potentially reflecting the abnormal HPA-axis function as observed in post-traumatic stress disorder, and future studies should investigate its neural/neuroendocrine foundation in further detail. Interestingly, experiencing additional (chronic) stress in adulthood seems to normalize these alterations in HPA-axis function, supporting the match/mismatch theory.

Mechanisms of Brain Glucocorticoid Resistance in Stress-Induced Psychopathologies

Exposure to stress activates the hypothalamic-pituitary-adrenal axis and leads to increased levels of glucocorticoid (GC) hormones. Prolonged elevation of GC levels causes neuronal dysfunction, decreases the density of synapses, and impairs neuronal plasticity. Decreased sensitivity to glucocorticoids (glucocorticoid resistance) that develops as a result of chronic stress is one of the characteristic features of stress-induced psychopathologies. In this article, we reviewed the published data on proposed molecular mechanisms that contribute to the development of glucocorticoid resistance in brain, including changes in the expression of the glucocorticoid receptor (GR) gene, biosynthesis of GR isoforms, and GR posttranslational modifications. We also present data on alterations in the expression of the FKBP5 gene encoding the main component of cell ultra-short negative feedback loop of GC signaling regulation. Recent discoveries on stress- and GR-induced changes in epigenetic modification patterns as well as normalizing action of antidepressants are discussed. GR and FKBP5 gene polymorphisms associated with stress-induced psychopathologies are described, and their role in glucocorticoid resistance is discussed.

Antidepressant-like effects of Xiaochaihutang in a neuroendocrine mouse model of anxiety/depression

ETHNOPHARMACOLOGICAL RELEVANCE

Hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis is often observed in the pathophysiology of depression. Antidepressant therapy can restore hippocampal neurogenesis to rescue the HPA axis regulation defects. Xiaochaihutang (XCHT), a famous Chinese herbal formula, has been used clinically in depressive disorders in China. Our previous studies have demonstrated XCHT improved depressive-like behaviors in chronic unpredictable mild stress rat, but the underlying mechanisms of XCHT on hippocampal neurogenesis and the HPA axis were still unclear.

MATERIALS AND METHODS

We used chronic corticosterone (CORT)-induced mouse model of anxiety/depression to investigate antidepressant-like effects of XCHT by several physical and behavioral testing, including body weight, coat state, open field test, elevated plus maze, tail suspension test and forced swimming test. The integrity of negative feedback function on HPA axis was assessed by the dexamethasone (DEX) suppression test. In addition, Ki-67 and doublecortin (DCX) were performed to assess hippocampal cell proliferation and neurogenesis by immunohistochemistry. Chemical profile of active constituents in brain after oral administration of XCHT was revealed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

Our results showed that oral administration of XCHT (2.3, 7 and 21g/kg) for 30 days remarkably normalized chronic CORT-induced the slowness in weight gain, the deterioration in coat state, the escape behavior in open field test and elevated plus maze, and the increase of immobility time in tail suspension test and forced swimming test. Moreover, XCHT significantly reversed chronic CORT-induced the reduction of DEX-induced plasma corticosterone/c-Fos suppression and Ki-67/DCX positive cells. Finally, a total 13 potential active constituents in brain were identified by UPLC-MS/MS after oral administration of XCHT, including 10 prototype components and 3 metabolites.

CONCLUSIONS

Our findings showed that XCHT could remarkably alleviate chronic CORT-induced anxiety/depression-like behaviors, which were probably attribute to promoting hippocampal neurogenesis and remodeling the integrity of the negative feedback loop on HPA axis. The constituents identified in brain might contribute to understanding the therapeutic basis of XCHT on depression.

Mineralocorticoid receptor function in depressed patients and healthy individuals

BACKGROUND

Many studies have shown disturbed glucocorticoid receptor (GR) in depressed patients. In contrast, only few studies targeted mineralocorticoid receptor (MR) function with inconclusive results. We examined the effects of the MR antagonist spironolactone on cortisol secretion in depressed patients and healthy individuals.

METHODS

Forty-eight unmedicated depressed patients (mean age 41.6years) and 45 age- and sex-matched healthy participants (40.7years) received the MR antagonist spironolactone (300mg) or placebo with three days apart in a randomized, double-blind, within-subject cross-over design. We measured salivary cortisol before ingestion of study medication (baseline) as well as +60min, +90min, +120min, +150min and 180min after baseline.

RESULTS

Repeated-measures ANOVA for area under the curve (AUCg) cortisol revealed a treatment effect with higher cortisol after spironolactone and a treatment by group interaction. Post-hoc analyses revealed higher cortisol in depressed patients compared to healthy participants in the placebo condition. In the spironolactone condition, the cortisol levels were not significantly different.

CONCLUSIONS

Potentially, impaired MR or GR signaling could be responsible for higher cortisol levels in depressed patients in the placebo condition. However, after MR blockade that increased cortisol secretion across groups leading to higher GR occupation, we found no differences between depressed patients and healthy controls. Thus, our results argue for depression-associated alterations in MR signaling rather than disturbed GR-mediated feedback inhibition.

Aging and the HPA axis: Stress and resilience in older adults

Hypothalamic-pituitary-adrenal (HPA) axis function may change over the course of aging, and altered diurnal or stress-induced secretion of the hormone cortisol could predispose older adults to negative health outcomes. We propose that psychological resilience may interact with diurnal cortisol to affect health outcomes later in life. Emotion regulation and social support are two constructs that contribute to resilience and exhibit age-specific patterns in older adults. Determining how the use of resilience resources interacts with age-related diurnal cortisol will improve our understanding of the pathways between stress, resilience, and well-being. In this review, we assess published studies evaluating diurnal cortisol in older adults to better understand differences in their HPA axis functioning. Evidence thus far suggests that diurnal cortisol may increase with age, although cross-sectional studies limit the conclusions that can be drawn. We also review extant evidence connecting age-specific signatures of emotion regulation and social support with diurnal cortisol. Conclusions are used to propose a preliminary model demonstrating how resilience resources may modulate the effects of cortisol on health in aging.

Preimplantation maternal stress impairs embryo development by inducing oviductal apoptosis with activation of the Fas system

STUDY QUESTION

What are the mechanisms by which the preimplantation restraint stress (PIRS) impairs embryo development and pregnancy outcome?

SUMMARY ANSWER

PIRS impairs embryo development by triggering apoptosis in mouse oviducts and embryos,and this involves activation of the Fas system.

WHAT IS KNOWN ALREADY

Although it is known that the early stages of pregnancy are more vulnerable than later stages to prenatalstress, studies on the effect of preimplantation stress on embryo developmentare limited. Furthermore, the mechanisms by which psychological stress impairs embryo development are largely unknown. These issues are worth exploring using the mouse PIRS models because restraint of mice is an efficient experimental procedure developed for studies of psychogenic stress.

STUDY DESIGN, SIZE AND DURATION

Mice of Kunming strain, the generalized lymphoproliferative disorder (gld) mice with a germline mutation F273L in FasL in a C57BL/6J genomic background and the wild-type C57BL/6J mice were used. Female and male mice were used 8-10 weeks and 10-12 weeks after birth, respectively. Female mice showing vaginal plugs were paired by weight and randomly assigned to restraint treatments or as controls. For restraint treatment, an individual mouse was put in a micro-cage with food and water available. Control mice remained in their cages with food and water during the time treated females were stressed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Female mice were exposed to PIRS for 48 h starting from 16:00 on the day of vaginal plug detection. At the end of PIRS, levels of glucorticoids (GC), corticotropin-releasing hormone (CRH)and redox potential were measured in serum, while levels of GC, GC receptor (GR), CRH, CRH receptor (CRHR), Fas and Fas ligand (FasL) protein, mRNAs for brain derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1), oxidative stress (OS) and apoptosis were examined in oviducts. Preimplantation development and levels of GR, Fas, redox potential and apoptosis were observed in embryos recovered at different times after the initiation of PIRS. The gld mice were used to confirm a role for the Fas system in triggering apoptosis of embryos and oviducts.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to those in control mice, while the number of blastocysts/mouse (5.0 ± 0.7 versus 11.1 ± 0.5), cell number/blastocyst (49.1 ± 1.3 versus 61.5 ± 0.9), percentages of term pregnancy (37.5% versus 90.9%) and litter size (3.7 ± 0.1versus 9.6 ± 0.6) decreased, blood CRH (560 ± 23 versus 455 ± 37 pg/ml), cortisol (27.3 ± 3.4 versus 5 ± 0.5 ng/ml) and OS index (OSI: 2.8 versus 1.7) increased significantly (all P < 0.05) following PIRS. In the oviduct, while levels of CRH (1175 ± 85 versus 881 ± 33 pg/100 mg), cortisol (28.9 ± 1.7 versus14 ± 4 ng/g), CRHR (2.3 ± 0.3 versus 1.0 ± 0.0), FasL (1.31 ± 0.06 versus 1.08 ± 0.05 ng/g), Fas (1.42 ± 0.13 versus 1.0 ± 0.0) and apoptotic cells (19.1 ± 0.5% versus 8.4 ± 0.4%) increased, levels of GR proteins (0.67 ± 0.14 versus 1.0 ± 0.0) and Igf-1 (0.6 ± 0.09 versus 1.0 ± 0.0) and Bdnf (0.73 ± 0.03 versus 1.0 ± 0.0) mRNAs decreased significantly (all P < 0.05 versus control) after PIRS. Mouse embryos expressed GR and Fas at all stages of preimplantation development and embryo OS (GSH/GSSG ratio: 0.88 ± 0.03 versus 1.19 ± 0.13) and annexin-positive cells (blastocysts: 31.4 ± 3.8% versus 10.96 ± 3.4%) increased significantly (P < 0.05) following PIRS. Furthermore, the detrimental effects of PIRS on embryo development and oviductal apoptosis were much reduced in gld mice. Thus, PIRS triggered apoptosis in oviductal cells with activation of the Fas/FasL system. The apoptotic oviductal cells promoted embryo apoptosis with reduced production of IGF-1 and BDNF and increased production of FasL.

LIMITATIONS, REASONS FOR CAUTION

Although important, the conclusions were drawn from limited results obtained using a single model in one species and thus they need further verification using other models and/or in other species. Furthermore, as differences in stressed samples were modest and sometimes not significant between gld and wild-type mice whereas differences between control and stressed samples were always present within gld mice, it is deduced that signaling pathways other than the Fas/FasL system might be involved as well in the PIRS-triggered apoptosis of oviducts and embryos.

WIDER IMPLICATIONS OF THE FINDINGS

The data are important for studies on the mechanisms by which psychological stress affects female reproduction, as FasL expression has been observed in human oviduct epithelium.

LARGE SCALE DATA

Not applicable.

STUDY FUNDING AND COMPETING INTERESTS

This study was supported by grants from the National Basic Research Program of China (Nos. 2014CB138503 and 2012CB944403), the China National Natural Science Foundation (Nos. 31272444 and 30972096) and the Animal breeding improvement program of Shandong Province. All authors declare that their participation in the study did not involve factual or potential conflicts of interests.