[The hypothalamic pituitary adrenal axis, glucocorticoid receptor function and relevance to depression]

Exploring the gut-brain Axis: Potential therapeutic impact of Psychobiotics on mental health

One of the most challenging and controversial issues in microbiome research is related to gut microbial metabolism and neuropsychological disorders. Psychobiotics affect human behavior and central nervous system processes via the gut-brain axis, involving neuronal, immune, and metabolic pathways. They have therapeutic potential in the treatment of several neurodegenerative and neurodevelopmental disorders such as depression, anxiety, autism, attention deficit hyperactivity disorder, Alzheimer's disease, Parkinson's disease, schizophrenia, Huntington's disease, anorexia nervosa, and multiple sclerosis. However, the mechanisms underlying the interaction between psychobiotics and the abovementioned diseases need further exploration. This review focuses on the relationship between gut microbiota and its impact on neurological and neurodegenerative disorders, examining the potential of psychobiotics as a preventive and therapeutic approach, summarising recent research on the gut-brain axis and the potential beneficial effects of psychobiotics, highlighting the need for further research and investigation in this area.

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.

Early life stress unravels epistatic genetic associations of cortisol pathway genes with depression

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis represents one of the most consistent pathophysiological findings in depressive disorders. Cortisol signaling is affected by proteins that mediate its cellular responses or alters its availability to mineralocorticoid and glucocorticoid receptors. In our study, we evaluated candidate genes that may influence the risk for depression and suicide due to its involvement in cortisol signaling. The aim of the study was to assess whether the genotypes of these genes are associated with the risk for depression, severity of depressive symptoms, suicidal ideation, and suicide attempts. And whether there is interaction between genes and early-life stress. In this study, 100 healthy controls and 140 individuals with depression were included. The subjects were clinically assessed using the 21-item GRID-Hamilton questionnaires (GRID-HAMD-21), Beck Scale for Suicidal Ideation (BSI), and the Childhood Trauma Questionnaire (CTQ). A robust multifactorial dimensionality reduction analysis was used to characterize the interactions between the genes HSD11B1, NR3C1, NR3C2, and MDR1 and early-life stress. It was found a significant association of the heterozygous genotype of the MDR1 gene rs1128503 polymorphism with reduced risk of at least one suicide attempt (OR: 0.08, p = 0.003*) and a reduction in the number of suicide attempts (β = -0.79, p = 0.006*). Furthermore, it was found that the MDR1 rs1228503 and NR3C2 rs2070951 genes interact with early-life stress resulting in a strong association with depression (p = 0.001). Our findings suggest that polymorphisms in the MDR1 and NR3C2 genes and their interaction with childhood trauma may be important biomarkers for depression and suicidal behaviors.

Evaluation of salivary stress markers and inflammatory cytokine levels in peri-implantitis patients

BACKGROUND AND OBJECTIVE

Psychological stress has been identified in some observational studies as a potential factor that may modify and affect periodontal diseases, but there are no similar data for peri-implantitis. The aim of this study was to determine the relationship between interleukin (IL)-1β, IL-6, IL-10, interferon (IFN)α inflammatory cytokines and the psychological stress-related markers, glucocorticoid receptor-α (GRα), and salivary α-amylase (sAA) gene expression levels in saliva samples obtained from healthy implants and peri-implantitis patients.

MATERIALS AND METHODS

The study included a total of 50 systemically healthy subjects. Peri-implant clinical parameters were recorded and psychological stress level was evaluated with the hospital anxiety and depression scale (HAD) and state-trait anxiety inventory (STAI) questionnaire forms. Following the evaluations, the patients were divided into 4 groups according their stress and clinical status (Ia, Ib, IIa, IIb). IL-1β, IL-6, IL-10, IFNα, GRα, sAA gene expression levels in the saliva samples were quantified by quantitative polymerase chain reaction (qPCR).

RESULTS

In the group of peri-implantitis who had a high score in stress level assessment scales, significantly higher IL-1β, IL-6, sAA expression levels were observed (p < 0.001). The IL-10 gene expression levels were lower in the groups with a high score in the stress level assessment scales (p < 0.001). GRα gene was expressed at lower levels in the group of peri-implantitis who had a high score in stress level assessment scales but the difference was not statistically significant (p = 0.065).

CONCLUSION

The study findings suggest that psychological stress may increase the inflammation associated with peri-implantitis by affecting cytokine expression levels.

CLINICAL RELEVANCE

To prevent peri-implantitis or reduce its prevalence, it could be beneficial to evaluate stress levels and identify individuals experiencing stress.

An industrialized diet as a determinant of methylation in the 1F region of the NR3C1 gene promoter

Background

Dietary composition can modify gene expression, favoring the development of chronic diseases via epigenetic mechanisms.

Objective

Our study aimed to investigate the relationship between dietary patterns and NR3C1 gene methylation in users of the Brazilian Public Unified Health System (SUS).

Methods

We recruited 250 adult volunteers and evaluated their socioeconomic status, psychosocial characteristics, lifestyle, and anthropometrics. Peripheral blood was collected and evaluated for cortisol levels, glycemia, lipid profile, and insulin resistance; methylation of CpGs 40-47 of the 1F region of the NR3C1 gene was also measured. Factors associated with degree of methylation were evaluated using generalized linear models (p < 0.05). Lifestyle variables and health variables were included as confounding factors.

Results

The findings of our cross-sectional study indicated an association between NR3C1 DNA methylation and intake of processed foods. We also observed relevant associations of average NR3C1 DNA across the segment analyzed, methylation in component 1 (40-43), and methylation in component 2 (44-47) with a pattern of consumption of industrialized products in relation to BMI, serum cortisol levels, and lipid profile. These results may indicate a relationship between methylation and metabolic changes related to the stress response.

Conclusion

These findings suggest an association of methylation and metabolic alterations with stress response. In addition, the present study highlights the significant role of diet quality as a stress-inducing factor that influences NR3C1 methylation. This relationship is further linked to changes in psychosocial factors, lifestyle choices, and cardiometabolic variables, including glucose levels, insulin resistance, and hyperlipidemia.

Antidepressant-like Effect of Oroxylum indicum Seed Extract in Mice Model of Unpredictable Chronic Mild Stress

Major depressive disorder (MDD) is one life-threatening disorder that is prevalent worldwide. The evident etiology of this disease is still poorly understood. Currently, herbal medicine is gaining more interest as an alternative antidepressant. Oroxylum indicum, which is used in traditional medicine and contains a potential antidepressive compound, baicalein, could have an antidepressive property. An in vitro monoamine oxidase-A (MAO-A) inhibitory assay was used to preliminarily screening for the antidepressant effect of O. indicum seed (OIS) extract. Mice were subjected to unpredictable chronic mild stress (UCMS) for 6 weeks, and the daily administration of OIS extract started from week 4. The mechanisms involved in the antidepressive activity were investigated. The OIS extract significantly alleviated anhedonia and despair behaviors in the UCMS-induced mouse model via two possible pathways: (i) it normalized the HPA axis function via the restoration of negative feedback (decreased FKBP5 and increased GR expressions) and the reduction in the glucocorticoid-related negative gene (SGK-1), and (ii) it improved neurogenesis via the escalation of BDNF and CREB expressions in the hippocampus and the frontal cortex. In addition, an HPLC analysis of the OIS extract showed the presence of baicalin, baicalein, and chrysin as major constituents. All of the results obtained from this study emphasize the potential of OIS extract containing baicalin and baicalein as an effective and novel alternative treatment for MDD.

The pathophysiology and management of depression in cardiac surgery patients

Background

Depression is common in the cardiac surgery population. This contemporary narrative review aims to explore the main pathophysiological disturbances underpinning depression specifically within the cardiac surgery population. The common non-pharmacological and pharmacological management strategies used to manage depression within the cardiac surgery patient population are also explored.

Methods

A total of 1291 articles were identified through Ovid Medline and Embase. The findings from 39 studies were included for qualitative analysis in this narrative review.

Results

Depression is associated with several pathophysiological and behavioral factors which increase the likelihood of developing coronary heart disease which may ultimately require surgical intervention. The main pathophysiological factors contributing to depression are well characterized and include autonomic nervous system dysregulation, excessive inflammation and disruption of the hypothalamic-pituitary-adrenal axis. There are also several behavioral factors in depressed patients associated with the development of coronary heart disease including poor diet, insufficient exercise, poor compliance with medications and reduced adherence to cardiac rehabilitation. The common preventative and management modalities used for depression following cardiac surgery include preoperative and peri-operative education, cardiac rehabilitation, cognitive behavioral therapy, religion/prayer/spirituality, biobehavioral feedback, anti-depressant medications, and statins.

Conclusion

This contemporary review explores the pathophysiological mechanisms leading to depression following cardiac surgery and the current management modalities. Further studies on the preventative and management strategies for postoperative depression in the cardiac surgery patient population are warranted.

Salivary biomarkers to evaluate psychological disorders in oral lichen planus: A systematic review with meta-analysis

OBJECTIVE

To analyze the use of salivary biomarkers to identify psychological disorders (anxiety, depression, and stress) in individuals with oral lichen planus (OLP).

MATERIALS AND METHODS

The search was made in Medline/Pubmed, Scopus, Web of Science, Virtual Health Library, ProQuest, and by cross-reference. Original case-control, cross-sectional, and cohort studies, in human subjects (age ≥18 years) with clinical and histopathological diagnosis, with or without the use of psychometric scales, published until June 2021, were included. Random-effects meta-analyses, subgroup analyses, and sensitivity were performed. Publication bias was measured using the Egger test and visual inspection of the funnel plot.

RESULTS

A total of 67 articles were found, of which 12 were included in the meta-analysis. Among the different biomarkers identified, it was only possible to perform a meta-analysis for cortisol. The mean difference between salivary cortisol levels in patients with OLP compared to controls was 3.43 ng/ml (95% CI: 1.20-5.65) with I2  = 98.9%. Studies considered outliers were removed and based on sensitivity analyses, results did not change, therefore, being stable.

CONCLUSION

The studies analyzed demonstrated that cortisol was the most quantified biomarker to identify psychological disorders; however, DHEA, IgA, adiponectin, and α-amylase were also evaluated.

Shared biological mechanisms of depression and obesity: focus on adipokines and lipokines

Depression and obesity are both common disorders currently affecting public health, frequently occurring simultaneously within individuals, and the relationship between these disorders is bidirectional. The association between obesity and depression is highly co-morbid and tends to significantly exacerbate metabolic and related depressive symptoms. However, the neural mechanism under the mutual control of obesity and depression is largely inscrutable. This review focuses particularly on alterations in systems that may mechanistically explain the in vivo homeostatic regulation of the obesity and depression link, such as immune-inflammatory activation, gut microbiota, neuroplasticity, HPA axis dysregulation as well as neuroendocrine regulators of energy metabolism including adipocytokines and lipokines. In addition, the review summarizes potential and future treatments for obesity and depression and raises several questions that need to be answered in future research. This review will provide a comprehensive description and localization of the biological connection between obesity and depression to better understand the co-morbidity of obesity and depression.

Health Professionals' Chronotype Association with Salivary Cortisol and Occupational Stress in Neonatal Intensive Care Units

Burnout syndrome has been reported among health workers, particularly those working in critical areas, and is considered a significant public health problem. This study aimed to investigate the relationship between chronotype and work-related stress, as measured by salivary cortisol levels and burnout, among health professionals working in neonatal intensive care units. A cross-sectional study was conducted across four public hospitals in Fortaleza, Ceará, Brazil. Two hundred and fifty-six health professionals were administered the brazilian version of the Burnout Characterization Scale, the morningness-eveningness questionnaire, for chronotype, a sociodemographic questionnaire that included lifestyle habits and a salivary cortisol test. The results indicated that morning chronotype workers were significantly associated with the following: advanced age (p < 0.001), female gender (p = 0.032), married status (p = 0.014), and having children (p = 0.030) compared to those with evening and intermediate chronotypes. However, no significant association was found between signs of burnout syndrome and chronotype (p = 0.316). Participants whose work shift did not match their chronotype had significantly higher initial salivary cortisol levels (p = 0.013). The findings suggest that adapting working hours to an individual's biological rhythm can help mitigate potential negative effects on physical and mental health. Thus, it is recommended that professionals' working hours be adjusted accordingly.

Prenatal stress modulates HPA axis homeostasis of offspring through dentate TERT independently of glucocorticoids receptor

In response to stressful events, the hypothalamic-pituitary-adrenal (HPA) axis is activated, and consequently glucocorticoids are released by the adrenal gland into the blood circulation. A large body of research has illustrated that excessive glucocorticoids in the hippocampus exerts negative feedback regulation of the HPA axis through glucocorticoid receptor (GR), which is critical for the homeostasis of the HPA axis. Maternal prenatal stress causes dysfunction of the HPA axis feedback mechanism in their offspring in adulthood. Here we report that telomerase reverse transcriptase (TERT) gene knockout causes hyperactivity of the HPA axis without hippocampal GR deficiency. We found that the level of TERT in the dentate gyrus (DG) of the hippocampus during the developmental stage determines the responses of the HPA axis to stressful events in adulthood through modulating the excitability of the dentate granular cells (DGCs) rather than the expression of GR. Our study also suggests that the prenatal high level of glucocorticoids exposure-induced hypomethylation at Chr13:73764526 in the first exon of mouse Tert gene accounted for TERT deficiency in the DG and HPA axis abnormality in the adult offspring. This study reveals a novel GR-independent mechanism underlying prenatal stress-associated HPA axis impairment, providing a new angle for understanding the mechanisms for maintaining HPA axis homeostasis.

Microbiota-Gut-Brain Axis in Major Depression: A New Therapeutic Approach

Major depression is impacted by the disruption of gut microbiota. Defects in gut microbiota can lead to microbiota-gut-brain axis dysfunction and increased vulnerability to major depression. While traditional chemotherapeutic approaches, such as antidepressant use, produce an overall partial therapeutic effect on depression, the gut microbiome has emerged as an effective target for better therapeutic outcomes. Recent representative studies on the microbiota hypothesis to explore the association between gut pathophysiology and major depression have indicated that restoring gut microbiota and microbiota-gut-brain axis could alleviate depression. We reviewed studies that supported the gut microbiota hypothesis to better understand the pathophysiology of depression; we also explored reports suggesting that gut microbiota restoration is an effective approach for improving depression. These findings indicate that gut microbiota and microbiota-gut-brain axis are appropriate new therapeutic targets for major depression.

Role of Brain-Gut-Microbiota Axis in Depression: Emerging Therapeutic Avenues

The human gut microbiota plays a significant role in the pathophysiology of central nervous system-related diseases. Recent studies suggest correlations between the altered gut microbiota and major depressive disorder (MDD). It is proposed that normalization of the gut microbiota alleviates MDD. The imbalance of brain-gut-microbiota axis also results in dysregulation of the hypothalamicpituitary- adrenal (HPA) axis. This imbalance has a crucial role in the pathogenesis of depression. Treatment strategies with certain antibiotics lead to the depletion of useful microbes and thereby induce depression like effects in subjects. Microbiota is also involved in the synthesis of various neurotransmitters (NTs) like 5-hydroxy tryptamine (5-HT; serotonin), norepinephrine (NE) and dopamine (DA). In addition to NTs, the gut microbiota also has an influence on brain derived neurotrophic factor (BDNF) levels. Recent research findings have exhibited that transfer of stress prone microbiota in mice is also responsible for depression and anxiety-like behaviour in animals. The use of probiotics, prebiotics, synbiotics and proper diet have shown beneficial effects in the regulation of depression pathogenesis. Moreover, transplantation of fecal microbiota from depressed individuals to normal subjects also induces depression-like symptoms. With the precedence of limited therapeutic benefits from monoamine targeting drugs, the regulation of brain-gut microbiota is emerging as a new treatment modality for MDDs. In this review, we elaborate on the significance of brain-gut-microbiota axis in the progression of MDD, particularly focusing on the modulation of the gut microbiota as a mode of treating MDD.

Microglia and HPA axis in depression: An overview of participation and relationship

Objectives: This narrative review article provides an overview on the involvement of microglia and the hypothalamic-pituitary-adrenal (HPA) axis in the pathophysiology of depression, as well investigates the mutual relationship between these two entities: how microglial activation can contribute to the dysregulation of the HPA axis, and vice versa.Methods: Relevant studies and reviews already published in the Pubmed electronic database involving the themes microglia, HPA axis and depression were used to meet the objectives.Results: Exposition to stressful events is considered a common factor in the mechanisms proposed to explain the depressive disorder. Stress can activate microglial cells, important immune components of the central nervous system (CNS). Moreover, another system involved in the physiological response to stressors is the hypothalamic-pituitary-adrenal (HPA) axis, the main stress response system responsible for the production of the glucocorticoid hormone (GC). Also, mediators released after microglial activation can stimulate the HPA axis, inducing production of GC. Likewise, high levels of GCs are also capable of activating microglia, generating a vicious cycle.Conclusion: Immune and neuroendocrine systems seems to work in a coordinated manner and that their dysregulation may be involved in the pathophysiology of depression since neuroinflammation and hypercortisolism are often observed in this disorder.

Morphine Perinatal Exposure Induces Long-Lasting Negative Emotional States in Adult Offspring Rodents

Psychoactive substances during pregnancy and lactation is a key problem in contemporary society, causing social, economic, and health disturbance. In 2010, about 30 million people used opioid analgesics for non-therapeutic purposes, and the prevalence of opioids use during pregnancy ranged from 1% to 21%, representing a public health problem. This study aimed to evaluate the long-lasting neurobehavioral and nociceptive consequences in adult offspring rats and mice exposed to morphine during intrauterine/lactation periods. Pregnant rats and mice were exposed subcutaneously to morphine (10 mg/kg/day) during 42 consecutive days (from the first day of pregnancy until the last day of lactation). Offspring were weighed on post-natal days (PND) 1, 5, 10, 15, 20, 30, and 60, and behavioral tasks (experiment 1) or nociceptive responses (experiment 2) were assessed at 75 days of age (adult life). Morphine-exposed female rats displayed increased spontaneous locomotor activity. More importantly, both males and female rats perinatally exposed to morphine displayed anxiety- and depressive-like behaviors. Morphine-exposed mice presented alterations in the nociceptive responses on the writhing test. This study showed that sex difference plays a role in pain threshold and that deleterious effects of morphine during pre/perinatal periods are nonrepairable in adulthood, which highlights the long-lasting clinical consequences related to anxiety, depression, and nociceptive disorders in adulthood followed by intrauterine and lactation morphine exposure.

The Gasotransmitter Hydrogen Sulfide and the Neuropeptide Oxytocin as Potential Mediators of Beneficial Cardiovascular Effects through Meditation after Traumatic Events

Trauma and its related psychological and somatic consequences are associated with higher cardiovascular morbidity. The regulation of both the gasotransmitter hydrogen sulfide (H2S) and the neuropeptide oxytocin (OT) have been reported to be affected during physical and psychological trauma. Both mediators are likely molecular correlates of trauma-induced cardiovascular complications, because they share parallel roles and signaling pathways in the cardiovascular system, both locally as well as on the level of central regulation and the vagus nerve. Meditation can alter the structure of specific brain regions and can have beneficial effects on cardiovascular health. This perspective article summarizes the evidence pointing toward the significance of H2S and OT signaling in meditation-mediated cardio-protection.

Hypothalamic-Pituitary-Adrenal axis dysfunction by early life stress

Evidence indicates that early life stress (ELS) may act as a risk factor for the development and maintenance of adulthood severe mental health disorders due to persistent dysregulation within the hypothalamic-pituitary-adrenal (HPA) axis. It is now broadly accepted that psychological stress may change the internal homeostatic state of an individual. The dysregulation seems to be a byproduct of changes noted in the HPA axis hormone's ability to bind to the glucocorticoid and mineralocorticoid receptors, crucial in maintaining homeostasis. Whenever there is an acute interruption of this balance, illness may result. The social and physical environments have an enormous impact on our physiology and behavior, and they influence the process of adaptation or 'allostasis'. The HPA axis response to stress can be thought of as a mirror of the organism's response to stress: acute responses are generally adaptive, but excessive or prolonged responses can lead to deleterious effects. Evidence indicates that early-life stress can induce persistent changes in the ability of the HPA axis to respond to stress in adulthood This review aims to examine and summarise the existing literature exploring the relationship between ELS with regards specifically to HPA axis functioning. The maintenance of the internal homeostatic state of an individual is proposed to be based on the ability of circulating glucocorticoids to exert negative feedback on the secretion of HPA hormones through binding to mineralocorticoid (MR) and glucocorticoid (GR) receptors limiting the vulnerability to diseases related to psychological stress in genetically predisposed individuals.

Effects of early life social experience on fear extinction and related glucocorticoid profiles - behavioral and neurochemical approaches in a rat model of PTSD

People may agonize over an intrusive fear-inducing memory even when the traumatic event has passed, which is the principle manifestation of posttraumatic stress disorder (PTSD). However, many traumatized people do not present symptoms of PTSD, implying that certain hidden factors help those individuals to cope with the traumatic stress. Increasing evidence suggests that early life experience may serve as a predisposing factor in the development of PTSD. For example, early life social deprivation disrupts the glucocorticoid system, one of the biological abnormalities of PTSD. By employing isolation rearing (IR) with a subsequent single prolonged stress (SPS) paradigm, we examined the hypothesis that early-life social experience may change the outcome of traumatic stress in both behavioral and neurochemical profiles. Behaviorally, the performance of rats on a Pavlovian fear conditioning test was measured to evaluate their retrieval ability of fear memory extinction. Neurochemically, plasma corticosterone levels and glucocorticoid receptor (GR), FK506-binding proteins 4 and 5 (FKBP4 and FKBP5) and early growth response-1 (Egr-1) expression were measured in GR-abundant brain areas, including the hypothalamus, medial prefrontal cortex, and hippocampus. Our results demonstrated an area-dependent IR effect on the SPS outcomes. IR prevented the SPS-impaired fear extinction retrieval ability and averted the SPS-elevated expression of GR, FKBP4, and Egr-1 in the hippocampus, whereas it did not change the SPS-reduced plasma corticosterone levels and SPS-enhanced GR activity in the mPFC and hypothalamus. The present study provides some new insights to support the hypothesis that early-life experience may play a role in the occurrence of PTSD.

N-3 PUFA Have Antidepressant-like Effects Via Improvement of the HPA-Axis and Neurotransmission in Rats Exposed to Combined Stress

Early life and adulthood stress increase vulnerability for mental illness, and eventually trigger depression. N-3 polyunsaturated fatty acids (PUFA) have antidepressant effects, but their effect on rats exposed to combined stress has been not investigated. This study aimed to investigate whether n-3 PUFA supplementation had antidepressant-like effects in rat models of depression induced by a combination of chronic mild stress (CMS) and maternal separation (MS) through the modulation of the hypothalamic-pituitary-adrenal (HPA) axis and neurotransmission. Rats were fed the n-3 PUFA diet during the pre-weaning or post-weaning period or for lifetime, and allocated to different groups based on the type of induced stress: non-stress (NS), CMS + MS, or CMS alone. N-3 PUFA improved the depressive behaviors of the CMS alone and CMS + MS groups and modulated the HPA-axis by reducing the circulating adrenocorticotropic hormone, corticosterone, and corticotropin-releasing factor expression, and increasing glucocorticoid receptor expression. N-3 PUFA also modulated brain phospholipid fatty acid concentration, thus reducing inflammatory cytokines; improved the serotonergic pathway, thus increasing the expression of the brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein (CREB), serotonin-1A receptor, and serum levels of serotonin; but did not affect glutamatergic neurotransmission. Furthermore, n-3 PUFA decreased the hippocampal expression of microRNA-218 and -132, increased that of microRNA-155, and its lifetime supplementation was more beneficial than pre- or post-weaning supplementation. This study suggests that n-3 PUFA has an antidepressant effect in rats exposed to combined stress, through the improvement of the HPA-axis abnormalities, the BDNF-serotonergic pathway, and the modulation of microRNAs.

Zinc, but not paracetamol, prevents depressive-like behavior and sickness behavior, and inhibits interferon-gamma and astrogliosis in rats

Considering all mental and addictive disorders, depression is the most responsible for years of life lost due to premature mortality and disability. Antidepressant drugs have limited effectiveness. Depression can be triggered by immune/inflammatory factors. Zinc and paracetamol interfere with immune system and have demonstrated beneficial effects on depression treatment when administered concomitant with antidepressant drugs. The objective of this study was to test zinc and/or paracetamol as treatments of depressive-like behavior, sickness behavior, and anxiety in rats, as well as to understand the central and peripheral mechanisms involved. Sickness behavior and depressive-like behavior were induced in rats with repetitive lipopolysaccharide (LPS, 1 mg/kg for two consecutive days) administrations. Rats received zinc and/or paracetamol for three consecutive days. Sickness behavior (daily body weight and open field general activity); anxiety (light-dark test); depressive-like/antidepressant behavior (forced swim test); plasma corticosterone and interferon (IFN)-gamma levels; and glial fibrillary acidic protein (GFAP) and tyrosine hydroxylase (TH) brain expression were evaluated. LPS induced sickness behavior and depressive-like behavior, as well as elevated IFN-gamma levels and increased GFAP expression. Zinc prevented both behavioral and biochemical impairments. Paracetamol and zinc + paracetamol association induced only slight beneficial effects. Anxiety, corticosterone, and TH do not seem be related with depression and the other behavioral and neuroimmune changes. In conclusion, zinc treatment was beneficial for sickness behavior and depressive-like behavior without concomitant administration of antidepressants. IFN-gamma and GFAP were linked with the expression of sickness behavior and depressive-like behavior and were also involved with the antidepressant effects. Therefore, zinc, IFN-gamma, and GFAP pathways should be considered for depression treatment.

Prebiotics may reduce serum concentrations of C-reactive protein and ghrelin in overweight and obese adults: a systematic review and meta-analysis

CONTEXT

Biochemical markers correlate positively with the development and severity of obesity, depression, and anxiety, and can be modulated by changes in intestinal microbiota composition.

OBJECTIVE

A systematic review and meta-analysis was conducted to determine the effects of prebiotics or synbiotics on blood biomarkers of obesity, depression, and anxiety (including: ACTH [adrenocorticotropic hormone], cortisol, leptin, ghrelin, TSH [thyroid-stimulating hormone], PTH [parathyroid hormone], vitamin D, BDNF [brain-derived neurotrophic factor], and PCR [polymerase chain reaction]) in individuals with overweight or obesity.

DATA SOURCES

MEDLINE, Web of Science, Scopus, and CENTRAL databases were searched, along with the reference lists of included articles. Authors were contacted for unpublished data.

STUDY SELECTION

RCT in individuals with overweight or obesity, supplemented with prebiotics or synbiotics, assessing any of the outcomes of interest.

DATA EXTRACTION

Data were extracted independently by three researchers.

RESULTS

Thirteen studies were identified up to March 7, 2018. Regarding outcomes, 1 study assessed leptin, 4 studies assessed ghrelin, and 10 studies assessed CRP (C-reactive protein). Meta-analysis showed reduction in serum concentrations of ghrelin (-37.17 pg/mL; 95%CI = -69.62, -4.73; P = 0.025) and CRP (SMD [standardized mean difference] = -0.31; 95%CI = -0.58, -0.04; P = 0.027) after supplementation of inulin-type fructans.

CONCLUSIONS

Prebiotics may help regulate blood concentrations of ghrelin and CRP in overweight or obese individuals.

Bioelectronic sensor mimicking the human neuroendocrine system for the detection of hypothalamic-pituitary-adrenal axis hormones in human blood

In the neuroendocrine system, corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH) play important roles in the regulation of the hypothalamic-pituitary-adrenal (HPA) system. Disorders of the HPA system lead to physiological problems, such as Addison's disease and Cushing's syndrome. Therefore, detection of CRH and ACTH is essential for diagnosing disorders related to the HPA system. Herein, receptors of the HPA axis were used to construct a bioelectronic sensor system for the detection of CRH and ACTH. The CRH receptor, corticotropin-releasing hormone receptor 1 (CRHR1), and the ACTH receptor, melanocortin 2 receptor (MC2R), were produced using an Escherichia coli expression system, and were reconstituted using nanodisc (ND) technology. The receptor-embedded NDs were immobilized on a floating electrode of a carbon nanotube field-effect transistor (CNT-FET). The constructed sensors sensitively detected CRH and ACTH to a concentration of 1 fM with high selectivity in real time. Furthermore, the reliable detection of CRH and ACTH in human plasma by the developed sensors demonstrated their potential in clinical and practical applications. These results indicate that CRHR1 and MC2R-based bioelectronic sensors can be applied for rapid and efficient detection of CRH and ACTH.

Neuroinflammation, Gut-Brain Axis and Depression

Psychiatric diseases are the manifestations that result from the individual's genetic structure, physiology, immunology and ways of coping with environmental stressors. The current psychiatric diagnostic systems do not include any systematic characterization in regard to neurobiological processes that reveal the clinical picture in individuals who got psychiatric diagnosis. It is obvious that further research in different areas is needed to understand the psychopathology. The problems in the functions of immune system and the correlation of neuroinflammatory processes with psychiatric disorders have been one of the main research topics of psychiatry in recent years and have contributed to our understanding of psychopathology. Recent advances in the fields of immunology and genetics as well as rapidly increasing knowledge on the effects of immunological processes on brain functions have drawn attention to the correlations between psychiatric disorders and immune system dysfunctions. There are still unfilled gaps in the biology, pathophysiology, and treatment of major depressive disorder, which is quite prevalent among the psychiatric disorders, can lead to significant disability, and frequently has a recurrent course. It appears that low-grade chronic neuroinflammation plays a key role in forming a basis for the interaction between psychological stress, impaired gut microbiota and major depressive disorder. In this review, the role of neuroinflammation in the etiopathogenesis of depression and the mechanism of action of the gut-brain axis that leads to this are discussed in the light of current studies.

Roman chamomile inhalation combined with clomipramine treatment improves treatment-resistant depression-like behavior in mice

It is well known that chamomile is one of the oldest known medicinal herbs and has been used to treat various disorders, but it is mainly German chamomile. The effects of Roman chamomile on depression still unclear. In this study, we used chronically stressed mice to investigate whether inhalation of Roman chamomile essential oil affects depression-like behavior. We previously reported that restraint and water immersion stress produce depression-like behavior and a blunted response to the tricyclic antidepressant clomipramine. Each mouse was exposed to restraint and water immersion stress for 15 days, and resistance to the effect of clomipramine was induced in a behavioral despair paradigm. In the present study, we found that cotreatment with clomipramine and inhalation of Roman chamomile attenuated depression-like behavior in a forced swim test. Next, we examined the hippocampal mRNA levels of two cytokines, tumor necrosis factor (TNF) alpha and interleukin-6 (IL-6); a neurotrophic factor, brain derived-neurotrophic factor (BDNF); and nerve growth factor (NGF). TNF alpha, IL-6 and BDNF mRNA levels did not change in the hippocampus of stressed mice. However, the NGF mRNA level was significantly decreased, and this decrease was not attenuated by treatment with clomipramine or inhalation of Roman chamomile alone. We also examined whether Roman chamomile combined with clomipramine treatment affects hippocampal neurogenesis and serum corticosterone levels. Stressed mice had fewer doublecortin (DCX)-positive cells in the subgranular zone of the dentate gyrus, but this was significantly attenuated by Roman chamomile and clomipramine treatment. In addition, the serum corticosterone level was also significantly decreased by treatment with Roman chamomile and clomipramine. These results suggest that Roman chamomile inhalation may enhance the antidepressant effect of clomipramine by increasing hippocampal neurogenesis and modulating corticosterone levels in patients with treatment-resistant depression.

The role of inflammation and the gut microbiome in depression and anxiety

The study of the gut microbiome has increasingly revealed an important role in modulating brain function and mental health. In this review, we underscore specific pathways and mechanisms by which the gut microbiome can promote the development of mental disorders such as depression and anxiety. First, we review the involvement of the stress response and immune system activation in the development of depression and anxiety. Then, we examine germ-free murine models used to uncover the role of the gut microbiome in developing and modulating pertinent activity in the brain and the immune system. We also document multiple pathways by which stress-induced inflammation harms brain function and ultimately affects mental health, and review how probiotic and prebiotic treatments have shown to be beneficial. Lastly, we provide an overview of gut microbiome-derived compounds (short-chain fatty acids, tryptophan catabolites, microbial pattern recognition) and related mechanisms (vagal nerve activity and fecal microbiota transplants) involved in mediating the influence of the gut microbiome to mental health. Overall, a picture of the gut microbiome playing a facilitating role between stress response, inflammation, and depression, and anxiety is emerging. Future research is needed to firmly establish the microbiome's causal role, to further elucidate the mechanisms by which gut microbes influence brain function and mental health, and to possibly develop treatments that improve mental health through microbiotic targets.

SSRIs and SNRIs (SRI) in Pregnancy: Effects on the Course of Pregnancy and the Offspring: How Far Are We from Having All the Answers?

Serotonin has important roles in the development of the brain and other organs. Manipulations of synaptic serotonin by drugs such as serotonin reuptake inhibitors (SRI) or serotonin norepinephrine reuptake inhibitors (SNRI) might alter their development and function. Of interest, most studies on the outcome of prenatal exposure to SRI in human have not found significant embryonic or fetal damage, except for a possible, slight increase in cardiac malformations. In up to a third of newborns exposed to SRI, exposure may induce transient neonatal behavioral changes (poor neonatal adaptation) and increased rate of persistent pulmonary hypertension. Prenatal SRI may also cause slight motor delay and language impairment but these are transient. The data on the possible association of prenatal SRIs with autism spectrum disorder (ASD) are inconsistent, and seem to be related to pre-pregnancy treatment or to maternal depression. Prenatal SRIs also appear to affect the hypothalamic hypophyseal adrenal (HPA) axis inducing epigenetic changes, but the long-term consequences of these effects on humans are as yet unknown. SRIs are metabolized in the liver by several cytochrome P450 (CYP) enzymes. Faster metabolism of most SRIs in late pregnancy leads to lower maternal concentrations, and thus potentially to decreased efficacy which is more prominent in women that are rapid metabolizers. Studies suggest that the serotonin transporter SLC6A4 promoter is associated with adverse neonatal outcomes after SRI exposure. Since maternal depression may adversely affect the child's development, one has to consider the risk of SRI discontinuation on the fetus and the child. As with any drug treatment in pregnancy, the benefits to the mother should be considered versus the possible hazards to the developing embryo/fetus.

Dysregulation of stress systems and nitric oxide signaling underlies neuronal dysfunction in Alzheimer's disease

Stress is a multimodal response involving the coordination of numerous body systems in order to maximize the chance of survival. However, long term activation of the stress response results in neuronal oxidative stress via reactive oxygen and nitrogen species generation, contributing to the development of depression. Stress-induced depression shares a high comorbidity with other neurological conditions including Alzheimer's disease (AD) and dementia, often appearing as one of the earliest observable symptoms in these diseases. Furthermore, stress and/or depression appear to exacerbate cognitive impairment in the context of AD associated with dysfunctional catecholaminergic signaling. Given there are a number of homologous pathways involved in the pathophysiology of depression and AD, this article will highlight the mechanisms by which stress-induced perturbations in oxidative stress, and particularly NO signaling, contribute to neurodegeneration.

Antidepressant-like activities of live and heat-killed Lactobacillus paracasei PS23 in chronic corticosterone-treated mice and possible mechanisms

Emerging evidence indicates that ingestion of specific probiotics, known as "psychobiotics", confer beneficial effects on mental health. This study investigated antidepressant-like effects and possible underlying mechanisms of Lactobacillus paracasei PS23 (PS23), live or heat-killed, in a mouse model of corticosterone-induced depression using fluoxetine as standard drug. PS23 were orally gavaged to mice from day 1 to 41 or fluoxetine from day 17 to 41 and injected with corticosterone from day 17 to 37. After the last corticosterone treatment, anxiety- and depression-like behaviors were tested within 4 days. On day 42, serum and brain tissue were collected 24 min after forced swim stress. Abnormal behavioral changes induced by corticosterone were ameliorated by treatment with live PS23 in open field and sucrose preference tests, with heat-killed PS23 in open field, forced swim and sucrose preference tests, and with fluoxetine in open field and forced swim tests. Furthermore, both live and heat-killed PS23 and fluoxetine reversed corticosterone-reduced protein levels of brain-derived neurotropic factor, mineralocorticoid, and glucocorticoid receptors in the hippocampus. In addition, live PS23 also reverses corticosterone-reduced serotonin levels in hippocampus, prefrontal cortex and striatum; whereas heat-killed PS23 reverses corticosterone-reduced dopamine levels in hippocampus and prefrontal cortex. And fluoxetine normalized reduced corticosterone level in serum. These studies showed that both live and heat-killed PS23 can reverse chronic corticosterone-induced anxiety- and depression-like behaviors and that may provide insights into the mechanism and a potential psychobiotic for depression management.

Identification of a Novel Functional Corticotropin-Releasing Hormone (CRH2) in Chickens and Its Roles in Stimulating Pituitary TSHβ Expression and ACTH Secretion

Corticotropin-releasing hormone (CRH), together with its structurally and functionally related neuropeptides, constitute the CRH family and play critical roles in multiple physiological processes. Recently, a novel member of this family, namely CRH2, was identified in vertebrates, however, its functionality and physiological roles remain an open question. In this study, using chicken (c-) as the animal model, we characterized the expression and functionality of CRH2 and investigated its roles in anterior pituitary. Our results showed that (1) cCRH2 cDNA is predicted to encode a 40-aa mature peptide, which shares a higher amino acid sequence identity to cCRH (63%) than to other CRH family peptides (23-38%); (2) Using pGL3-CRE-luciferase reporter system, we demonstrated that cCRH2 is ~15 fold more potent in activating cCRH receptor 2 (CRHR2) than cCRHR1 when expressed in CHO cells, indicating that cCRH2 is bioactive and its action is mainly mediated by CRHR2; (3) Quantitative real-time PCR revealed that cCRH2 is widely expressed in chicken tissues including the hypothalamus and anterior pituitary, and its transcription is likely controlled by promoters near exon 1, which display strong promoter activity in cultured DF-1 and HEK293 cells; (4) In cultured chick pituitary cells, cCRH2 potently stimulates TSHβ expression and shows a lower potency in inducing ACTH secretion, indicating that pituitary/hypothalamic CRH2 can regulate pituitary functions. Collectively, our data provides the first piece of evidence to suggest that CRH2 play roles similar, but non-identical, to those of CRH, such as its differential actions on pituitary, and this helps to elucidate the roles of CRH2 in vertebrates.

Advance in Stress for Depressive Disorder

Stress is an adaptive response to environment aversive stimuli and a common life experience of one's daily life. Chronic or excessive stress especially that happened in early life is found to be deleterious to individual's physical and mental health, which is highly related to depressive disorders onset. Stressful life events are consistently considered to be the high-risk factors of environment for predisposing depressive disorders. In linking stressful life events with depressive disorder onset, dysregulated HPA axis activity is supposed to play an important role in mediating aversive impacts of life stress on brain structure and function. Increasing evidence have indicated the strong association of stress, especially the chronic stress and early life stress, with depressive disorders development, while the association of stress with depression is moderated by genetic risk factors, including polymorphism of SERT, BDNF, GR, FKBP5, MR, and CRHR1. Meanwhile, stressful life experience particularly early life stress will exert epigenetic modification in these risk genes via DNA methylation and miRNA regulation to generate long-lasting effects on these genes expression, which in turn cause brain structural and functional alteration, and finally increase the vulnerability to depressive disorders. Therefore, the interaction of environment with gene, in which stressful life exposure interplay with genetic risk factors and epigenetic modification, is essential in predicting depressive disorders development. As the mediator of environmental risk factors, stress will function together with genetic and epigenetic mechanism to influence brain structure and function, physiology and psychology, and finally the vulnerability to depressive disorders.

Cortisol levels and cognitive profile in major depression: A comparison of currently and previously depressed patients

The association between depressive symptoms and elevated cortisol levels, and depression and cognitive functioning, has been less robust in outpatients with symptoms in the mild to moderate range. Furthermore, the association between elevated cortisol levels and cognitive functioning is unclear. In the present study, currently depressed (n = 37), previously depressed (n = 81) and never depressed controls (n = 50) were assessed on a range of neuropsychological measures. Salivary cortisol was measured in the morning and evening. Participants with current depression were non-hospitalized and had symptoms predominately in the mild to moderate range. Elevated salivary evening cortisol, but not morning cortisol, was significantly related to depressive symptoms. The difference in cortisol levels between the previously depressed group and the never depressed controls was not significant. The groups had significantly different cognitive profiles, with the currently depressed performing poorer on tasks related to working memory compared to the never depressed controls. Both the currently and previously depressed performed worse on attentional tasks. The findings indicate that outpatients with mild to moderate depression have elevated cortisol levels and limited mild cognitive impairments. Furthermore, mild impairments in attention may persist after remission, indicating that this could be a trait-marker in depression. The present study did not find support for a significant relationship between cortisol and cognitive functioning.

Targeted Ubiquitin-Proteasomal Proteolysis Pathway in Chronic Social Defeat Stress

Stressful events promote psychopathogenic changes that might contribute to the development of mental illnesses. Some individuals tend to recover from the stress response, while some do not. However, the molecular mechanisms of stress resilience during stress are not well-characterized. Here, we identify proteomic changes in the hippocampus using proteomic technique to examine mice following chronic social defeat stress. We showed that small ubiquitin-like modifier (SUMO)-1 expression was significantly decreased in susceptible mice following chronic social defeat stress. We also examined a protein inhibitor of activated signal transducer of transcription (PIAS)1 levels, an E3 SUMO-protein ligase protein inhibitor of activated STAT1, which is known to interact with SUMO-1. PIAS1 was shown to be profoundly decreased and monoamine oxidase (MAO)-A increased in the hippocampus of susceptible mice following chronic social defeat stress. Furthermore, the manipulated PIAS1 expression in the hippocampus also has an influence on glucocorticoid receptor (GR) translocation. We also found that knockdown of PIAS1 expression in the hippocampus then subject to submaximal stress increased GR to glucocorticoid response element (GRE)-binding site on the MAO-A promoter. The present study raises the possibility of different levels of PIAS1 between individuals in response to chronic social defeat stress and that such differences may contribute to the susceptibility to stress.

A Comprehensive Overview on Stress Neurobiology: Basic Concepts and Clinical Implications

Stress is recognized as an important issue in basic and clinical neuroscience research, based upon the founding historical studies by Walter Canon and Hans Selye in the past century, when the concept of stress emerged in a biological and adaptive perspective. A lot of research after that period has expanded the knowledge in the stress field. Since then, it was discovered that the response to stressful stimuli is elaborated and triggered by the, now known, stress system, which integrates a wide diversity of brain structures that, collectively, are able to detect events and interpret them as real or potential threats. However, different types of stressors engage different brain networks, requiring a fine-tuned functional neuroanatomical processing. This integration of information from the stressor itself may result in a rapid activation of the Sympathetic-Adreno-Medullar (SAM) axis and the Hypothalamus-Pituitary-Adrenal (HPA) axis, the two major components involved in the stress response. The complexity of the stress response is not restricted to neuroanatomy or to SAM and HPA axes mediators, but also diverge according to timing and duration of stressor exposure, as well as its short- and/or long-term consequences. The identification of neuronal circuits of stress, as well as their interaction with mediator molecules over time is critical, not only for understanding the physiological stress responses, but also to understand their implications on mental health.

Recognizing Depression from the Microbiota⁻Gut⁻Brain Axis

Major depression is one of the leading causes of disability, morbidity, and mortality worldwide. The brain⁻gut axis functions are disturbed, revealed by a dysfunction of the brain, immune system, endocrine system, and gut. Traditional depression treatments all target the brain, with different drugs and/or psychotherapy. Unfortunately, most of the patients have never received any treatment. Studies indicate that gut microbiota could be a direct cause for the disorder. Abnormal microbiota and the microbiota⁻gut⁻brain dysfunction may cause mental disorders, while correcting these disturbance could alleviate depression. Nowadays, the gut microbiota modulation has become a hot topic in treatment research of mental disorders. Depression is closely related with the health condition of the brain⁻gut axis, and maintaining/restoring the normal condition of gut microbiota helps in the prevention/therapy of mental disorders.

The Associations Between Oxytocin and Trauma in Humans: A Systematic Review

Studies have shown that traumatic experiences may affect hormonal systems mediated by the hypothalamic-pituitary-adrenal (HPA) axis and the oxytocinergic system. This effect is the result of long-term impairments in hypothalamic structures and negative feedback mechanisms within the HPA axis, structures that mediate the response to stress. This deregulation reduces the production and release of cortisol and oxytocin (OXT), which may alter stress responses and lead to increased vulnerability to impairments from stressful experiences. The presence of gene polymorphisms might also have an impact on the vulnerability to psychopathology. We made a systematic review of articles dealing with the relationship between OXT and traumatic emotional experiences in humans. Thirty-five studies were reviewed and significant associations between experiences of emotional trauma (ET) and OXT were found. The main results showed that the presence of ET and post-traumatic stress disorder (PTSD) is strongly associated with reductions in endogenous OXT, and also that the acute effects of OXT administrations in individuals with ET tend to be anxiolytic only in less severe forms. In victims of recent traumatic experiences (RTE), OXT increased the re-experience of traumas and restored the function of different neural networks associated with fear control/extinction in PTSD patients. The results available also suggest that gene receptor polymorphisms may have a protective function in different outcomes after the experience of traumatic events. We conclude that the relationship between ET and OXT is multifaceted, complex, and mediated by contextual and individual factors. Directions for future studies are suggested considering the gaps in the available literature.

In vivo imaging of oxidative stress and fronto-limbic white matter integrity in young adults with mood disorders

Fronto-limbic connectivity is compromised in mood disorders, as reflected by impairments in white matter (WM) integrity revealed by diffusion tensor imaging. Although the underlying mechanisms remain unclear, disruption to normal myelination due to oxidative stress is thought to play a key role. We aimed to determine whether fronto-limbic WM integrity is compromised, and associated with in vivo antioxidant levels (indexed by glutathione; GSH), in young adults with unipolar depression (DEP) and bipolar (BD) disorders. Ninety-four patients with DEP, 76 with BD and 59 healthy controls (18-30 years) underwent diffusion tensor and proton magnetic resonance spectroscopy imaging. Fractional anisotropy (FA) was calculated from the cingulum bundle (cingulate, hippocampus), fornix, stria terminalis (ST) and uncinate fasciculus tracts. GSH concentration was measured in anterior cingulate cortex (ACC) and hippocampus (HIPP). Compared to controls, DEP showed significantly reduced FA in ST, whereas BD did not significantly differ in FA across the five tracts. There were significant positive correlations between ST-FA and HIPP-GSH across groups. Regression analysis revealed that having DEP or BD and reduced HIPP-GSH were significantly associated with reduced ST-FA. Similarly, decreased ST-FA was associated with poorer neuropsychological performance in conjunction with having DEP. Our findings suggest a structural disconnectivity specific to the limbic region of young adults with DEP. Decreased WM integrity was associated with depleted levels of hippocampal GSH suggesting that this particular disruption may be linked to oxidative stress at early stages of illness. Young adults with BD do not have the same degree of impairment.

Cortisol Modulation by Ayahuasca in Patients With Treatment Resistant Depression and Healthy Controls

Major depression is a highly prevalent mood disorder, affecting about 350 million people, and around 30% of the patients are resistant to currently available antidepressant medications. Recent evidence from a randomized controlled trial (RCT) supports the rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression. The aim of this study was to explore the effect of ayahuasca on plasma cortisol and awakening salivary cortisol response, in the same group of treatment-resistant patients (MD) and in healthy volunteers (C). Subjects received a single dose of ayahuasca or placebo (dosing session), and both plasma and awakening salivary cortisol response were measured at baseline (before dosing session) and 48 h after the dosing session. Baseline assessment (D0) showed blunted awakening salivary cortisol response and hypocortisolemia in patients, with respect to healthy controls. Salivary cortisol was also measured during dosing session, and we observed higher increases for both C and MD that ingested ayahuasca than placebo. After 48 h from the dosing session with ayahuasca, patients' awakening salivary cortisol response is similar to the ones detected in controls. No significant changes in plasma cortisol levels were observed 48 h after the sessions. Therefore, these findings point to new evidence on the modulation of salivary cortisol levels as a result of an ayahuasca session, both in healthy and depressive volunteers. Considering that cortisol acts in regulation of distinct physiological pathways, emotional and cognitive processes, it is assumed to be critically involved to the etiology of depression and its regulation seems to be important for the treatment and remission of major depression, ayahuasca use as antidepressant should be further investigated. Moreover, this study highlights the importance of psychedelics in the treatment of human mental disorders.

FKBP5 and specific microRNAs via glucocorticoid receptor in the basolateral amygdala involved in the susceptibility to depressive disorder in early adolescent stressed rats

Exposure to stressful events induces depressive-like symptoms and increases susceptibility to depression. However, the molecular mechanisms are not fully understood. Studies reported that FK506 binding protein51 (FKBP5), the co-chaperone protein of glucocorticoid receptors (GR), plays a crucial role. Further, miR-124a and miR-18a are involved in the regulation of FKBP5/GR function. However, few studies have referred to effects of early life stress on depressive-like behaviours, GR and FKBP5, as well as miR-124a and miR-18a in the basolateral amygdala (BLA) from adolescence to adulthood. This study aimed to examine the dynamic alternations of depressive-like behaviours, GR and FKBP5, as well as miR-124a and miR-18a expressions in the BLA of chronic unpredictable mild stress (CUMS) rats and dexamethasone administration rats during the adolescent period. Meanwhile, the GR antagonist, RU486, was used as a means of intervention. We found that CUMS and dexamethasone administration in the adolescent period induced permanent depressive-like behaviours and memory impairment, decreased GR expression, and increased FKBP5 and miR-124a expression in the BLA of both adolescent and adult rats. However, increased miR-18a expression in the BLA was found only in adolescent rats. Depressive-like behaviours were positively correlated with the level of miR-124a, whereas GR levels were negatively correlated with those in both adolescent and adult rats. Our results suggested FKBP5/GR and miR-124a in the BLA were associated with susceptibility to depressive disorder in the presence of stressful experiences in early life.

Molecular Mechanisms Underlying the Anti-depressant Effects of Resveratrol: a Review

Major depression is a public health problem, affecting 121 million people worldwide. Patients suffering from depression present high rates of morbidity, causing profound economic and social impacts. Furthermore, patients with depression present cognitive impairments, which could influence on treatment adherence and long-term outcomes. The pathophysiology of major depression is not completely understood yet but involves reduced levels of monoamine neurotransmitters, bioenergetics, and redox disturbances, as well as inflammation and neuronal loss. Treatment with anti-depressants provides a complete remission of symptoms in approximately 50% of patients with major depression. However, these drugs may cause side effects, as sedation and weight gain. In this context, there is increasing interest in studies focusing on the anti-depressant effects of natural compounds found in the diet. Resveratrol is a polyphenolic phytoalexin (3,4',5-trihydroxystilbene; C₁₄H₁₂O₃; MW 228.247 g/mol) and has been found in peanuts, berries, grapes, and wine and induces anti-oxidant, anti-inflammatory, and anti-apoptotic effects in several mammalian cell types. Resveratrol also elicits anti-depressant effects, as observed in experimental models using animals. Therefore, resveratrol may be viewed as a potential anti-depressant agent, as well as may serve as a model of molecule to be modified aiming to ameliorate depressive symptoms in humans. In the present review, we describe and discuss the anti-depressant effects of resveratrol focusing on the mechanism of action of this phytoalexin in different experimental models.

Corticosterone influences gerbil (Meriones unguiculatus) prostatic morphophysiology and alters its proliferation and apoptosis rates

Glucocorticoids (GCs) are hormones that are widely used in medicine; but although side effects are generally recognised, little is known about the precise mechanisms that is implicated in many of these side effects. Furthermore, GCs are highly correlated with stress and behaviour disorders. This study evaluated the effects of the glucocorticoid corticosterone on the ventral prostate of the Mongolian gerbil. Male gerbils (Meriones unguiculatus) (n = 5) received intraperitoneal injections of saline or corticosterone in doses of 0.5 mg/kg/day and 1.5 mg/kg/day for 5 days; while some of the animals were killed immediately after the treatment, the others were killed 5 days after the treatment period. The data show that corticosterone influences the structure and functionality of this organ. This hormone has anti-proliferative and anti-apoptotic properties in the prostate. In addition, the frequencies of the androgen (AR), oestrogen (ERα, ERβ) and glucocorticoid (GR) receptors changed. The frequencies of AR, GR and ERβ decreased in the Ct1/5 group; in the groups with rest period, the frequencies of GR increased and ERβ decreased in the epithelium. Changes in the proliferative index, apoptotic index and receptor activity may have contributed to the emergence of prostatic morphological alterations, such as the presence of cellular debris and inflammatory cells. Different doses of corticosterone had variable effects on the prostate, with a higher dose showing subtler effects and a lower dose showing more striking effects. The corticosterone effects on nuclear receptors were reverted or attenuated after a rest period, which was not observed for proliferation and apoptosis. In summary, we have demonstrated that corticosterone might influence the prostatic morphophysiology and that these changes may be linked in some way to the altered receptor distribution.

Cortisol and DHEA in development and psychopathology

Dehydroepiandrosterone (DHEA) and cortisol are the most abundant hormones of the human fetal and adult adrenals released as end products of a tightly coordinated endocrine response to stress. Together, they mediate short- and long-term stress responses and enable physiological and behavioral adjustments necessary for maintaining homeostasis. Detrimental effects of chronic or repeated elevations in cortisol on behavioral and emotional health are well documented. Evidence for actions of DHEA that offset or oppose those of cortisol has stimulated interest in examining their levels as a ratio, as an alternate index of adrenocortical activity and the net effects of cortisol. Such research necessitates a thorough understanding of the co-actions of these hormones on physiological functioning and in association with developmental outcomes. This review addresses the state of the science in understanding the role of DHEA, cortisol, and their ratio in typical development and developmental psychopathology. A rationale for studying DHEA and cortisol in concert is supported by physiological data on the coordinated synthesis and release of these hormones in the adrenal and by their opposing physiological actions. We then present evidence that researching cortisol and DHEA necessitates a developmental perspective. Age-related changes in DHEA and cortisol are described from the perinatal period through adolescence, along with observed associations of these hormones with developmental psychopathology. Along the way, we identify several major knowledge gaps in the role of DHEA in modulating cortisol in typical development and developmental psychopathology with implications for future research.

A translational approach to clinical practice via stress-responsive glucocorticoid receptor signaling

A recent article by Kwan and colleagues could elegantly demonstrate the necessary interaction between neuronal serotonin (5-HT) systems and the hypothalamic-pituitary-adrenal (HPA) axis through glucocorticoid receptors (GR), producing an adequate stress response, in this case, responding to hypoxia with an increase in hematopoietic stem and progenitor cells (HSPC). There is an intricate system connecting brain, body and mind and this exchange is only possible when all these systems-nervous, endocrine, and immune-have receptors on critical cells to receive information (via messenger molecules) from each of the other systems. There is evidence that the expression and function of GR in the hippocampus, mainly MR, is regulated by the stimulation of 5-HT receptors. Stressful stimuli increase 5-HT release and turnover in the hippocampus, and it seems reasonable to suggest that some of the changes in mineralocorticoid and GR expression may be mediated, in part at least, by the increase in 5-HT. Also serotonin and HPA axis dysfunctions have already been implicated in a variety of psychiatric disorders, especially depression. Early life stress (ELS) can have profound impact on these systems and can predispose subjects to a variety of adult metabolic and psychiatric conditions. It is important to analyze the mechanisms of this complex interaction and its subsequent programming effects on the stress systems, so that we can find new ways and targets for treatment of psychiatric disorders. Different areas of research on basic biological sciences are now being integrated and this approach will hopefully provide several new insights, new pharmacological targets and improve our global understanding of these highly debilitating chronic conditions, that we now call mental disorders.

Further validation of the affective bias test for predicting antidepressant and pro-depressant risk: effects of pharmacological and social manipulations in male and female rats

RATIONALE

Affective biases are hypothesised to contribute to the cause and treatment of mood disorders. We have previously found that affective biases, associated with learning and memory, are observed following acute treatments with a range of antidepressant and pro-depressant manipulations.

OBJECTIVE

This study aimed to test if similar biases are observed in male and female Sprague Dawley (SD) rats. We also test whether the stress hormone, corticosterone, induces a negative bias in the affective bias test (ABT) consistent with its putative role in the development of depression. We then use a meta-analysis to compare our findings with data published for the Lister Hooded rats.

METHODS

The ABT uses a within-subject study design where animals learn to associate distinct digging substrates, encountered on different days, with the same value food reward. Exposure to one substrate is paired with a treatment manipulation (drug or environmental) and the other with a control condition. A preference test is used to test if the treatment has induced a positive or negative bias.

RESULTS

Consistent with previous data, both male and female SD rats exhibit similar positive affective biases following treatment with the antidepressant, venlafaxine, and social play and negative affective biases following FG 7142 (benzodiazepine inverse agonist) and social stress. Acute treatment with corticosterone induced a negative bias.

CONCLUSIONS

These data add to the translational validity of the ABT and suggest that corticosterone can induce a negative affective bias following acute treatment, an effect which may contribute to its long-term effects on mood.

The secretion, synthesis, and metabolism of cortisol and its downstream genes in the H-P-I axis of rare minnows (Gobiocypris rarus) are disrupted by acute waterborne cadmium exposure

The H (hypothalamic)-P (pituitary)-I (interrenal) axis plays a critical role in the fish stress response and is regulated by several factors. Cadmium (Cd) is one of the most toxic heavy metals in the world, but its effects on the H-P-I axis of teleosts are largely unknown. Using rare minnow (Gobiocypris rarus) as an experimental animal, we found that Cd only disrupted the secretion and synthesis of cortisol. Neither hormones at the H or P level nor the expressions of their receptor genes (corticotropin-releasing hormone receptor (CRHR) and melanocortin receptor 2 (MC2R)) were affected. Steroidogenic acute regulator (StAR), CYP11A1 and CYP11B1, which encode the key enzymes in the cortisol synthesis pathway, were significantly up-regulated in the kidney (including the head kidney). The level of 11β-HSD2, which is required for the conversion of cortisol to cortisone, was increased in the kidney, intestine, brain, and hepatopancreas, whereas the expression of 11β-HSD1, which encodes the reverse conversion enzyme, was increased in the gill, kidney and almost unchanged in other tissues. The enzyme activity concentration of 11β-HSD2 was increased in the kidney as well. The level of glucocorticoid receptor (GR) decreased in the intestine, gill and muscle, and the key GR regulator FK506 binding protein5 (FKBP5) was up-regulated in the GR-decreased tissues, whereas the level of nuclear receptor co-repressor 1 (NCoR1), another GR regulator remained almost unchanged. Thus, GR, FKBP5 and 11β-HSD2 may be involved in Cd-induced cortisol disruption.

Onset, timing, and exposure therapy of stress disorders: mechanistic insight from a mathematical model of oscillating neuroendocrine dynamics

BACKGROUND

The hypothalamic-pituitary-adrenal (HPA) axis is a neuroendocrine system that regulates numerous physiological processes. Disruptions in the activity of the HPA axis are correlated with stress-related diseases such as post-traumatic stress disorder (PTSD) and major depressive disorder. In this paper, we characterize "normal" and "diseased" states of the HPA axis as basins of attraction of a dynamical system describing the inhibition of peptide hormones such as corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH) by circulating glucocorticoids such as cortisol (CORT).

RESULTS

In addition to including key physiological features such as ultradian oscillations in cortisol levels and self-upregulation of CRH neuron activity, our model distinguishes the relatively slow process of cortisol-mediated CRH biosynthesis from rapid trans-synaptic effects that regulate the CRH secretion process. We show that the slow component of the negative feedback allows external stress-induced reversible transitions between "normal" and "diseased" states in novel intensity-, duration-, and timing-dependent ways.

CONCLUSION

Our two-step negative feedback model suggests a mechanism whereby exposure therapy of stress disorders such as PTSD may act to normalize downstream dysregulation of the HPA axis. Our analysis provides a causative rationale for improving treatments and guiding the design of new protocols.