Early life adversity and the epigenetic programming of hypothalamic-pituitary-adrenal function

Are There Epigenetic Oxytocin-Mediated Effects on the Mother and Infant during Physiological Childbirth?

INTRODUCTION

Studies have shown that long-term positive behavioural and physiological changes are induced in connection with vaginal, physiological birth, and skin-to-skin contact after birth in mothers and babies. Some of these effects are consistent with the effect profile of oxytocin. This scoping review explores whether epigenetic changes of the oxytocin gene and of the oxytocin receptor gene (OTR) are involved in these effects.

METHODS

We searched Pubmed, Medline, BioMed Central, Cochrane Library, OVID, and Web of Science for evidence of epigenetic changes in connection with childbirth in humans, with a particular focus on the oxytocin system.

RESULTS

There were no published studies identified that were related to epigenetic changes of oxytocin and its receptor in connection with labour, birth, and skin-to-skin contact after birth in mothers and babies. However, some studies were identified that showed polymorphisms of the oxytocin receptor influenced the progress of labour. We also identified studies in which the level of global methylation was measured in vaginal birth and caesarean section, with conflicting results. Some studies identified differences in the level of methylation of single genes linked to various effects, for example, immune response, metabolism, and inflammation. In some of these cases, the level of methylation was associated with the duration of labour or mode of birth. We also identified some studies that demonstrated long-term effects of mode of birth and of skin-to-skin contact linked to changes in oxytocin function.

CONCLUSION

There were no studies identified that showed epigenetic changes of the oxytocin system in connection with physiological birth. The lack of evidence, so far, regarding epigenetic changes did not exclude future demonstrations of such effects, as there was a definite role of oxytocin in creating long-term effects during the perinatal period. Such studies may not have been performed. Alternatively, the oxytocin linked effects might be indirectly mediated via other receptors and signalling systems. We conclude that there is a significant lack of research examining long-term changes of oxytocin function and long-term oxytocin mediated adaptive effects induced during physiological birth and skin-to-skin contact after birth in mothers and their infants.

Maternal Separation Combined With Limited Bedding Increases Anxiety-Like Behavior and Alters Hypothalamic-Pituitary-Adrenal Axis Function of Male BALB/cJ Mice

Early life stress (ELS) is considered a risk factor for the development of psychiatric conditions, including depression and anxiety disorder. Individuals that live in adverse environments are usually exposed to multiple stressors simultaneously, such as maternal neglect, maltreatment, and limited resources. Nevertheless, most pre-clinical ELS models are designed to explore the impact of these events separately. For this reason, this study aims to investigate the effects of a combined model of ELS on anxiety-like behavior and hypothalamic-pituitary-adrenal (HPA) axis related targets. From PND 2 to PND 15 BALB/cJ mice were exposed simultaneously to maternal separation (MS; 3 h per day) and limited bedding (LB; ELS group) or left undisturbed (CT group). Maternal behavior was recorded in intercalated days, from PND 1 to PND 9. Male offspring were tested for anxiety-like behavior from PND 53 to PND 55 in the open field test (OF), elevated plus-maze (EPM), and light/dark test (LD). After behavioral testing, animals were euthanized, and glucocorticoid receptor (Nr3c1), corticotrophin-releasing hormone (Crh), and its receptor type 1 (Crhr1) gene expression in the hypothalamus were measured. Moreover, plasma corticosterone levels were analyzed. We observed that ELS dams presented altered quality of maternal care, characterized by a decrease in arched-back nursing, and an increase in passive nursing. Stressed dams also showed an increase in the number of exits from the nest when compared to CT dams. Furthermore, ELS animals showed increased anxiety-like behavior in the OF, EPM, and LD. Regarding gene expression, we identified an increase in hypothalamus Crh levels of ELS group when compared to CT animals, while no differences in Nr3c1 and Crhr1 expression were observed. Finally, stressed animals showed decreased levels of plasma corticosterone when compared to the CT group. In conclusion, we observed an alteration in maternal behavior in ELS dams. Later in life, animals exposed to the combined model of ELS showed increased levels of anxiety-like behavior. Moreover, the central and peripheral HPA measures observed could indicate a dysregulation in HPA function provoked by ELS exposure.

An epigenome-wide association study of early-onset major depression in monozygotic twins

Major depression (MD) is a debilitating mental health condition with peak prevalence occurring early in life. Genome-wide examination of DNA methylation (DNAm) offers an attractive complement to studies of allelic risk given it can reflect the combined influence of genes and environment. The current study used monozygotic twins to identify differentially and variably methylated regions of the genome that distinguish twins with and without a lifetime history of early-onset MD. The sample included 150 Caucasian monozygotic twins between the ages of 15 and 20 (73% female; Mage = 17.52 SD = 1.28) who were assessed during a developmental stage characterized by relatively distinct neurophysiological changes. All twins were generally healthy and currently free of medications with psychotropic effects. DNAm was measured in peripheral blood cells using the Infinium Human BeadChip 450 K Array. MD associations with early-onset MD were detected at 760 differentially and variably methylated probes/regions that mapped to 428 genes. Genes and genomic regions involved neural circuitry formation, projection, functioning, and plasticity. Gene enrichment analyses implicated genes related to neuron structures and neurodevelopmental processes including cell-cell adhesion genes (e.g., PCDHA genes). Genes previously implicated in mood and psychiatric disorders as well as chronic stress (e.g., NRG3) also were identified. DNAm regions associated with early-onset MD were found to overlap genetic loci identified in the latest Psychiatric Genomics Consortium meta-analysis of depression. Understanding the time course of epigenetic influences during emerging adulthood may clarify developmental phases where changes in the DNA methylome may modulate individual differences in MD risk.

Epigenetic mechanisms activated by childhood adversity

Adverse childhood experiences (ACE) impair health and life expectancy and may result in an epigenetic signature that drives increased morbidity primed during early stages of life. This literature review focuses on the current evidence for epigenetic-mediated programming of brain and immune function resulting from ACE. To address this aim, a total of 88 articles indexed in PubMed before August 2019 concerning ACE and epigenetics were surveyed. Current evidence partially supports epigenetic programming of the hypothalamic-pituitary-adrenal axis, but convincingly shows that ACE impairs immune function. Additionally, the needs and challenges that face this area are discussed in order to provide a framework that may help to clarify the role of epigenetics in the long-lasting effects of ACE.

Maternal separation-induced increases in vascular stiffness are independent of circulating angiotensinogen levels

The renin-angiotensin system (RAS) precursor angiotensinogen (AGT) has been implicated in the functional and mechanical alterations of the vascular wall in response to high-fat diet (HFD). Previously, we showed that HFD exacerbates angiotensin II-induced constriction in isolated aortic rings from male rats exposed to maternal separation (MatSep), a model of early-life stress. Thus, the aim of this study was to investigate whether MatSep increases AGT secretion promoting vascular stiffness in rats fed a HFD. Male Wistar-Kyoto MatSep offspring were separated (3 h/day, postnatal days 2-14), and undisturbed littermates were used as controls. At weaning, rats were fed for 17 wk a normal diet (ND) or a HFD, 18% or 60% kcal from fat, respectively. In plasma, there was a main effect of MatSep reducing AGT concentration (P < 0.05) but no effect due to diet. In urine, ND-fed MatSep rats displayed higher AGT concentrations that were further increased by HFD (P < 0.05 vs. control). AGT mRNA abundance and protein expression were increased in adipose tissue from HFD-fed MatSep rats compared with control rats (P < 0.05). No significant differences in liver and kidney AGT levels were found between groups. In addition, MatSep augmented vascular stiffness assessed on freshly isolated aortic rings from ND-fed rats (P < 0.05), yet HFD did not worsen vascular stiffness in either MatSep or control rats. There was no correlation between plasma AGT and vascular stiffness in ND-fed rats; however, this relationship was negative in HFD-fed MatSep rats only (P < 0.05). Therefore, this study shows that MatSep-induced increases in vascular stiffness are independent of diet or plasma AGT.NEW & NOTEWORTHY This study demonstrates that there was no correlation between circulating levels of angiotensinogen (AGT) and the development of vascular stiffness in rats exposed to early-life stress and fed a normal diet. This study also shows that early-life stress-induced hypersensitive vascular contractility to angiotensin II in rats fed a high-fat diet is independent of circulating levels of AGT and occurs without further progression of vascular stiffness. Our data show that early-life stress primes the adipose tissue to secrete AGT in a sex- and species-independent fashion.

Sex-specific associations between person and environment-related childhood adverse events and levels of cortisol and DHEA in adolescence

BACKGROUND

Person and environment-related childhood adverse events have been demonstrated to increase the risk of impaired mental health in later life differently for boys and girls. Altered hypothalamic pituitary adrenal (HPA)-axis functioning has been suggested as a key mechanism underlying this association. Cortisol and dehydroepiandrosterone (DHEA) are both output hormones of the HPA-axis. DHEA may have a protective function against long-term exposure to increased levels of cortisol, but has been little investigated in relation to childhood adversity.

OBJECTIVE

We aimed to test the associations between person-, and environment-related childhood adversity and levels of cortisol, DHEA and cortisol/DHEA ratio in adolescent boys and girls.

METHODS

A total of 215 Dutch adolescents participated in the study and filled out the 27-item Adverse Life Events Questionnaire for the assessment of childhood adversity, which was split up in separate scores for person-related and environment-related events. Cortisol and DHEA concentrations and cortisol/DHEA ratio were determined in proximal 3 cm long hair segments. Additionally, saliva samples were collected immediately and 30 minutes after waking up, at noon and at 8 pm. Multiple linear regression analyses were used to test associations between childhood adversity and cortisol and DHEA concentrations, for boys and girls separately, with age, BMI and pubertal development as covariates.

RESULTS

Data were available for 74 boys and 116 girls with a mean age of 15.7 years (SD = 2.0). Higher levels of person-related childhood adversity were associated with higher hair DHEA levels in girls and with higher hair cortisol levels in boys. A trend towards a significant association was observed between higher levels of environment-related childhood adversity and higher DHEA levels in boys. Neither person- nor environment related childhood adversity was associated with cortisol/DHEA ratio. A trend was observed for environment-related childhood adversity and lower daily cortisol output in boys.

CONCLUSION

We found differential associations between childhood adversity and cortisol and DHEA levels in girls and boys, for respectively person-related and environment-related childhood adversity. Our findings suggest that different types of childhood adversity are not only linked to levels of cortisol, but also to DHEA concentrations, in a sex-specific manner, with possible future implications for mental health.

Rapid and Prolonged Antidepressant-like Effect of Crocin Is Associated with GHSR-Mediated Hippocampal Plasticity-related Proteins in Mice Exposed to Prenatal Stress

Prenatal stress (PNS) has a prolonged and adverse effect on offspring, leading to a significantly increased vulnerability to developing depression in their later life. Traditional therapies have delayed onset and limited efficacy; thus, it remains an urgent need to find novel medications with fast-onset and high-efficacy potentials. Crocin, with its structure clearly examined, has shown antidepressant-like effects. However, few studies extensively investigated its effect especially in mice exposed to PNS. Using an established PNS model, we tested whether crocin could have a rapid and persistent antidepressant-like effect in PNS mice. Growth hormone secretagogue receptor (GHSR) and phosphoinositide 3-kinase (PI3K) inhibitors were used to test their effects in antidepressant-like effect of crocin. Hippocampal GHSR-PI3K signaling was examined both in PNS mice treated with a single dose of crocin and in combination of GHSR inhibitor. PNS mice showed depression-like behaviors at juvenile and adulthood, and crocin induced an instant and persistent antidepressant-like response in PNS mice in a dose-dependent manner. Moreover, crocin increased the expression of hippocampal synaptic plasticity-associated proteins through the restoration of GHSR-PI3K signaling. Inhibitions of both GHSR and PI3K abolished the effect of crocin in alleviating depressive-like behaviors. More importantly, GHSR inhibitor JMV2959 blocked the enhanced expression of hippocampal plasticity-related proteins induced by crocin. The present study demonstrated that crocin induced a fast-onset and prolonged antidepressant effect in PNS mice and suggested that GHSR-PI3K signaling may play a key role in crocin's effect at least partially by a restoration of hippocampal synaptic plasticity-associated proteins.

Hormones and human developmental plasticity

Natural selection favors the evolution of mechanisms that optimize the allocation of resources and time among competing traits. Hormones mediate developmental plasticity, the changes in the phenotype that occur during ontogeny. Despite their highly conserved functions, the flexibilities of human hormonal systems suggest a strong history of adaptation to variable environments. Physiological research on developmental plasticity has focused on the early programming effects of stress, the hypothalamus-pituitary-adrenal axis (HPAA) and the hypothalamus-pituitary-gonadal axis (HPGA) during critical periods, when the hormones produced have the strongest influence on the developing brain. Often this research emphasizes the maladaptive effects of early stressful experiences. Here we posit that the HPAA and HPAG systems in human developmental plasticity have evolved to be responsive to complex and dynamic problems associated with human sociality. The lengthy period of human offspring dependency, and its associated brain development and risks, is linked to the uniquely human combination of stable breeding bonds, extensive paternal effort in a multi-male group, extended bilateral kin recognition, grandparenting, and controlled exchange of mates among kin groups. We evaluate an evolutionary framework that integrates proximate physiological explanations with ontogeny, phylogeny, adaptive function, and comparative life history data.

Investigating the impact of early-life adversity on physiological, immune, and gene expression responses to acute stress: A pilot feasibility study

OBJECTIVE

Exposure to early-life adversity (ELA) can result in long-term changes to physiological systems, which predispose individuals to negative health outcomes. This biological embedding of stress-responsive systems may operate via dysregulation of physiological resources in response to common stressors. The present pilot study outlines a novel experimental design to test how young adults' exposure to ELA influences neuroendocrine and inflammatory responses to acute stress.

MATERIALS AND METHODS

Participants were 12 males (mean age = 21.25), half of whom endorsed at least three significant adverse events up to age 18 years ('ELA group'), and half who confirmed zero ('controls'). Using a randomized within-subjects, between-groups experimental design, we induced acute psychosocial stress (Trier Social Stress Test, TSST), and included a no-stress control condition one week apart. During these sessions, we obtained repeated measurements of physiological reactivity, gene expression of the glucocorticoid receptor (NR3C1), and plasma levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-8 and TNFα) over a 4-hour window post-test.

RESULTS

In this pilot study, the ELA group evinced higher cortisol response and blunted NR3C1 gene expression in response to the TSST compared with controls, while no differences were observed in the no-stress condition. For pro-inflammatory cytokines, only IL-6 increased significantly in response to the TSST, with no differences between the two groups.

CONCLUSION

Overall, this pilot feasibility study provides a framework to investigate the biological embedding of early-adversity via dysregulation across physiological and genomic systems in response to acute psychosocial stress. ELA may program such systems in a maladaptive manner more likely to manifest during times of duress, predisposing individuals to the negative health consequences of everyday stressors. Future studies with larger sample size including both males and females are needed to replicate and expand upon these preliminary findings.

How Early Life Adversity Influences Defensive Circuitry

Childhood maltreatment increases the likelihood of developing anxiety disorders in humans. Early life adversity (ELA) paradigms in rodents produce lasting increases in avoidant and inhibitory responses to both immediate and nonspecific threats, collectively referred to as defensive behaviors. This approach provides an opportunity to thoroughly investigate the underlying mechanisms, an effort that is currently under way. In this review, we consider the growing literature indicating that ELA alters the rhythmic firing of neurons in brain regions associated with defensive behavior, as well as potential neuronal, glial, and extracellular matrix contributions to functional changes in this circuitry. We also consider how ELA studies in rodents may inform us about both susceptible and resilient outcomes in humans.

Early-Life Stress Induces Depression-Like Behavior and Synaptic-Plasticity Changes in a Maternal Separation Rat Model: Gender Difference and Metabolomics Study

More than 300 million people suffer from depressive disorders globally. People under early-life stress (ELS) are reportedly vulnerable to depression in their adulthood, and synaptic plasticity can be the molecular mechanism underlying such depression. Herein, we simulated ELS by using a maternal separation (MS) model and evaluated the behavior of Sprague-Dawley (SD) rats in adulthood through behavioral examination, including sucrose preference, forced swimming, and open-field tests. The behavior tests showed that SD rats in the MS group were more susceptible to depression- and anxiety-like behaviors than did the non-MS (NMS) group. Nissl staining analysis indicated a significant reduction in the number of neurons at the prefrontal cortex and hippocampus, including the CA1, CA2, CA3, and DG regions of SD rats in the MS group. Immunohistochemistry results showed that the percentages of synaptophysin-positive area in the prefrontal cortex and hippocampus (including the CA1, CA2, CA3, and DG regions) slice of the MS group significantly decreased compared with those of the NMS group. Western blot analysis was used to assess synaptic-plasticity protein markers, including postsynaptic density 95, synaptophysin, and growth-associated binding protein 43 protein expression in the cortex and hippocampus. Results showed that the expression levels of these three proteins in the MS group were significantly lower than those in the NMS group. LC-MS/MS analysis revealed no significant differences in the peak areas of sex hormones and their metabolites, including estradiol, testosterone, androstenedione, estrone, estriol, and 5β-dihydrotestosterone. Through the application of nontargeted metabolomics to the overall analysis of differential metabolites, pathway-enrichment results showed the importance of arginine and proline metabolism; pantothenate and CoA biosyntheses; glutathione metabolism; and the phenylalanine, tyrosine, and tryptophan biosynthesis pathways. In summary, the MS model caused adult SD rats to be susceptible to depression, which may regulate synaptic plasticity through arginine and proline metabolism; pantothenate and CoA biosyntheses; glutathione metabolism; and phenylalanine, tyrosine, and tryptophan biosyntheses.

Epigenetics, Development, and Psychopathology

Epigenetic mechanisms govern the transcription of the genome. Research with model systems reveals that environmental conditions can directly influence epigenetic mechanisms that are associated with interindividual differences in gene expression in brain and neural function. In this review, we provide a brief overview of epigenetic mechanisms and research with relevant rodent models. We emphasize more recent translational research programs in epigenetics as well as the challenges inherent in the integration of epigenetics into developmental and clinical psychology. Our objectives are to present an update with respect to the translational relevance of epigenetics for the study of psychopathology and to consider the state of current research with respect to its potential importance for clinical research and practice in mental health.

Vulnerable and resilient cognitive performance related to early life stress: The potential mediating role of dopaminergic receptors in the medial prefrontal cortex of adult mice

RATIONALE

Exposure to early life stress (ELS) is known to have pronounced effects on the prefrontal cortex (PFC). However, not all individuals exposed to ELS manifest the same neurobiological and cognitive phenotypes when adults. Dopamine signaling could be a key factor in understanding the effects of stress on PFC-related cognitive function.

OBJECTIVES

We aimed to investigate the differential effects of ELS on cognitive performance of adult mice and the dopaminergic receptors expression in the PFC.

METHODS

BALB/c males were exposed to the maternal separation (MS) procedure and their cognitive performance on the eight-arm radial maze (8-RAM) were assessed during adulthood. For molecular-level assessments, we performed mRNA expression analyses for dopamine receptors-DRD1, DRD2, DRD3-and Hers1 expression in the medial PFC.

RESULTS

While MS produced an overall impairment on 8-RAM, the stressed animals could be divided in two groups based on their performance: those with impaired cognitive performance (vulnerable to maternal separation, V-MS) and those without any impairment (resilient to maternal separation, R-MS). V-MS animals showed increased DRD1 and DRD2 expression in comparison with other groups. Errors on 8-RAM were also positively correlated with DRD1 and DRD2 mRNA expression.

CONCLUSIONS

Our findings suggest a potential role of the dopaminergic system in the programming mechanisms of cognitive vulnerability and resilience related to ELS.

Multilevel Impact of Prenatal Risk and Protective Factors on Stress Biology and Infant Development: Study protocol of BABIP prospective birth cohort from Turkey

Prenatal environment has long-lasting effects on offspring development and health. Research on prenatal stress identified various mechanisms of these effects, from changes in epigenetic and gene expression profiles to Maternal-Placental-Fetal (MPF) stress biology. There is also evidence for the role of additional risk and protective factors influencing the impact of prenatal stress on maternal and infant outcomes. Considering these findings, we present the study protocol of BABIP, a prospective birth cohort from Turkey. The aim of the project is to investigate the effect of prenatal stress on MPF stress biology (i.e. neuroendocrine, immune and metabolic systems), differential DNA methylation and gene expression patterns, and infant birth and developmental outcomes. We are recruiting 150 pregnant women and their babies for a longitudinal project with 4 time points: 20-24 (T1) and 30-34 (T2) weeks of pregnancy, and 1-month (T3) and 4-months (T4) after giving birth. Maternal early and prenatal environment (prenatal stress, early life stress, psychosocial resources, and health-related behaviors) are assessed during pregnancy with MPF stress biology, DNA methylation and gene expression measures. Infant birth outcomes, DNA methylation and development are assessed postpartum. BABIP is the first prospective birth cohort from Turkey with extensive measures on prenatal environment and health. Through investigating the multilevel impact of prenatal stress and related risk and protective factors during and after pregnancy, BABIP will contribute to our understanding of the mechanisms by which prenatal environment influences infant development and health. Being the first such cohort from Turkey, it may also allow identification of prenatal risk and protective factors specific to the context and population in Turkey.

Biomarkers of suicidal behaviors: A comprehensive critical review

Suicide is a relevant worldwide public health problem. Many studies have shown that different demographic and clinical factors are potentially associated with suicidal behavior. Other studies have reported data about the role of biomarkers in the onset of suicidal behaviors. Specifically, researchers have found that suicidal risk may be increased by abnormalities in serotonergic system, hypothalamic-pituitary-adrenal axis, lipid metabolism, immune system and neuronal plasticity. The identification of specific biological parameters associated with self-harm may be helpful to implement prevention strategies and also to detect new therapeutic strategies. In this review, we summarize and analyze the results of main studies about neurobiological mechanisms related to suicidal behavior, also exploring the possible interconnection between the different biological systems.

Unraveling the epigenetic landscape of depression: focus on early life stress

Depression is a devastating psychiatric disorder caused by a combination of genetic predisposition and life events, mainly exposure to stress. Early life stress (ELS) in particular is known to "scar" the brain, leading to an increased susceptibility to developing depression later in life via epigenetic mechanisms. Epigenetic processes lead to changes in gene expression that are not due to changes in DNA sequence, but achieved via modulation of chromatin modifications, DNA methylation, and noncoding RNAs. Here we review common epigenetic mechanisms including the enzymes that take part in reading, writing, and erasing specific epigenetic marks. We then describe recent developments in understanding how ELS leads to changes in the epigenome that are manifested in increased susceptibility to depression-like abnormalities in animal models. We conclude with highlighting the need for future studies that will potentially enable the utilisation of the understanding of epigenetic changes linked to ELS for the development of much-needed novel therapeutic strategies and biomarker discovery.
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Aberrant Epigenomic Modulation of Glucocorticoid Receptor Gene (NR3C1) in Early Life Stress and Major Depressive Disorder Correlation: Systematic Review and Quantitative Evidence Synthesis

Early life stress (ELS) induced by psychological trauma, child maltreatment, maternal separation, and domestic violence predisposes to psycho-behavioral pathologies during adulthood, namely major depressive disorder (MDD), anxiety, and bipolar affective disorder. While environmental data are available in illustrating this association, data remain to be established on the epigenomic underpinning of the nexus between ELS and MDD predisposition. Specifically, despite the observed aberrant epigenomic modulation of the NR3C1, a glucocorticoid receptor gene, in early social adversity and social threats in animal and human models, reliable scientific data for intervention mapping in reducing social adversity and improving human health is required. We sought to synthesize the findings of studies evaluating (a) epigenomic modulations, mainly DNA methylation resulting in MDD following ELS, (b) epigenomic modifications associated with ELS, and (c) epigenomic alterations associated with MDD. A systematic review and quantitative evidence synthesis (QES) were utilized with the random effect meta-analytic procedure. The search strategy involved both the PubMed and hand search of relevant references. Of the 1534 studies identified through electronic search, 592 studies were screened, 11 met the eligibility criteria for inclusion in the QES, and 5 examined ELS and MDD; 4 studies assessed epigenomic modulation and ELS, while 2 studies examined epigenomic modulations and MDD. The dense DNA methylation of the 1F exon of the NR3C1, implying the hypermethylated region of the glucocorticoid receptor gene, was observed in the nexus between ELS and MDD, common effect size (CES) = 14.96, 95%CI, 10.06-19.85. With respect to epigenomic modulation associated with child ELS, hypermethylation was observed, CES = 23.2%, 95%CI, 8.00-38.48. In addition, marginal epigenomic alteration was indicated in MDD, where hypermethylation was associated with increased risk of MDD, CES = 2.12%, 95%CI, -0.63-4.86. Substantial evidence supports the implication of NR3C1 and environmental interaction, mainly DNA methylation, in the predisposition to MDD following ELS. This QES further supports aberrant epigenomic modulation identified in ELS as well as major depressive episodes involving dysfunctional glucocorticoid-mediated negative feedback as a result of allostatic overload. These findings recommend prospective investigation of social adversity and its predisposition to the MDD epidemic via aberrant epigenomic modulation. Such data will facilitate early intervention mapping in reducing MDD in the United States population.

Implication of Spiritual Network Support System in Epigenomic Modulation and Health Trajectory

With challenges in understanding the multifactorial etiologies of disease and individual treatment effect heterogeneities over the past four decades, much has been acquired on how physical, chemical and social environments affect human health, predisposing certain subpopulations to adverse health outcomes, especially the socio-environmentally disadvantaged (SED). Current translational data on gene and adverse environment interaction have revealed how adverse gene-environment interaction, termed aberrant epigenomic modulation, translates into impaired gene expression via messenger ribonucleic acid (mRNA) dysregulation, reflecting abnormal protein synthesis and hence dysfunctional cellular differentiation and maturation. The environmental influence on gene expression observed in most literature includes physical, chemical, physicochemical and recently social environment. However, data are limited on spiritual or religious environment network support systems, which reflect human psychosocial conditions and gene interaction. With this limited information, we aimed to examine the available data on spiritual activities characterized by prayers and meditation for a possible explanation of the nexus between the spiritual network support system (SNSS) as a component of psychosocial conditions, implicated in social signal transduction, and the gene expression correlate. With the intent to incorporate SNSS in human psychosocial conditions, we assessed the available data on bereavement, loss of spouse, loneliness, social isolation, low socio-economic status (SES), chronic stress, low social status, social adversity (SA) and early life stress (ELS), as surrogates for spiritual support network connectome. Adverse human psychosocial conditions have the tendency for impaired gene expression through an up-regulated conserved transcriptional response to adversity (CTRA) gene expression via social signal transduction, involving the sympathetic nervous system (SNS), beta-adrenergic receptors, the hypothalamus-pituitary-adrenal (HPA) axis and the glucocorticoid response. This review specifically explored CTRA gene expression and the nuclear receptor subfamily 3 group C member 1 (NR3C1) gene, a glucocorticoid receptor gene, in response to stress and the impaired negative feedback, given allostatic overload as a result of prolonged and sustained stress and social isolation as well as the implied social interaction associated with religiosity. While more remains to be investigated on psychosocial and immune cell response and gene expression, current data on human models do implicate appropriate gene expression via the CTRA and NR3C1 gene in the SNSS as observed in meditation, yoga and thai-chi, implicated in malignant neoplasm remission. However, prospective epigenomic studies in this context are required in the disease causal pathway, prognosis and survival, as well as cautious optimism in the application of these findings in clinical and public health settings, due to unmeasured and potential confoundings implicated in these correlations.

Ancestral Fluoxetine Exposure Sensitizes Zebrafish to Venlafaxine-Induced Reductions in Cortisol and Spawning

Owing to the prevalence of depression during childbearing, mothers can be prescribed multiple antidepressants; however, little is known about the risk and consequences to the offspring or subsequent generations. Fluoxetine (FLX) is usually the first-line of pharmacological treatment for affective disorders in pregnant women, with venlafaxine (VEN) used as secondary treatment. Given that FLX and VEN readily cross the placenta, a fetus from a treated pregnant woman is potentially at risk of the endocrine disruptive effects of these chemicals. Pharmaceutical agents, including FLX and VEN, reach aquatic ecosystems through sewage release; thus, fish could also be inadvertently affected. We report the results from a 6-day FLX exposure during early zebrafish development to an environmentally relevant level (0.54 µg/L in water) and a concentration detected in the cord blood of FLX-treated pregnant women (54 µg/L in water). The FLX exposure reduced the stress response (arithmetic difference between the stress-induced and unstressed whole-body cortisol levels) in the adult female and male zebrafish, an effect that persisted for four generations. To model the possibility of a second antidepressant exposure, filial generation 4 was exposed to VEN (5 µg/L). We found that FLX exposure sensitized these descendants to VEN. VEN treatment further suppressed cortisol production in females and decreased spawning rates in adult pairs. This is an important demonstration that in an animal model, a brief ancestral exposure of great-great-grandparents to the selective serotonin reuptake inhibitor FLX will shape the physiological responses of future generations to the serotonin and norepinephrine reuptake inhibitor VEN.

Cortisol disruption and transgenerational alteration in the expression of stress-related genes in zebrafish larvae following fluoxetine exposure

Fluoxetine (FLX), the active ingredient in well-known therapeutic drugs such as Prozac, is highly prescribed worldwide to treat affective disorders even among pregnant women and adolescents. Given that FLX readily crosses the placenta, a fetus from a treated pregnant woman is potentially at risk from unintended effects of the chemical. Moreover, FLX reaches aquatic ecosystems at biologically active levels through sewage release, so fish may also be inadvertently affected. We previously demonstrated that FLX exposure to environmentally- (Low FLX Lineage; LFL) and human- (High FLX Lineage; HFL) relevant concentrations during the first 6 days of life in zebrafish (ZF; Danio rerio) reduced cortisol levels in the adults (F₀), an effect that persisted across 3 consecutive unexposed generations (F₁ to F₃). Here, we show that the transcriptional profile of selected genes in the steroidogenesis pathway in the F₀ whole-larvae varied in magnitude and direction in both FLX lineages, despite the same attenuated cortisol phenotype induced by both concentrations. We also observed an up-regulation in the transcript levels of some steroidogenic-related genes and a down-regulation of a gene involved in the inactivation of cortisol in the F₃ HFL larvae. These findings on the transcript levels of the selected genes in the larvae from F₀ and F₃ suggest that specific coping mechanism(s) are activated in descendants to attempt to counteract the disruptive effects of FLX. Our data are cause for concern, given the increasing prescription rates of FLX and other antidepressants, and the potential long-term negative impacts on humans and aquatic organisms.

Early Life Stress Restricts Translational Reactivity in CA3 Neurons Associated With Altered Stress Responses in Adulthood

Early life experiences program brain structure and function and contribute to behavioral endophenotypes in adulthood. Epigenetic control of gene expression by those experiences affect discrete brain regions involved in mood, cognitive function and regulation of hypothalamic-pituitary-adrenal (HPA) axis. In rodents, acute restraint stress increases the expression of the repressive histone H3 lysine 9 tri-methylation (H3K9me3) in hippocampal fields, including the CA3 pyramidal neurons. These CA3 neurons are crucially involved in cognitive function and mood regulation as well as activation of glucocorticoid (CORT) secretion. CA3 neurons also exhibit structural and functional changes after early-life stress (ELS) as well as after chronic stress in adulthood. Using a protocol of chronic ELS induced by limited bedding and nesting material followed by acute-swim stress (AS) in adulthood, we show that mice with a history of ELS display a blunted CORT response to AS, despite exhibiting activation of immediate early genes after stress similar to that found in control mice. We find that ELS induced persistently increased expression of the repressive H3K9me3 histone mark in the CA3 subfield at baseline that was subsequently decreased following AS. In contrast, AS induced a transient increase of this mark in control mice. Using translating ribosome affinity purification (TRAP) method to isolate CA3 translating mRNAs, we found that expression of genes of the epigenetic gene family, GABA/glutamate family, and glucocorticoid receptors binding genes were decreased transiently in control mice by AS and showed a persistent reduction in ELS mice. In most cases, AS in ELS mice did not induce gene expression changes. A stringent filtering of genes affected by AS in control and ELS mice revealed a noteworthy decrease in gene expression change in ELS mice compared to control. Only 18 genes were selectively regulated by AS in ELS mice and encompassed pathways such as circadian rhythm, inflammatory response, opioid receptors, and more genes included in the glucocorticoid receptor binding family. Thus, ELS programs a restricted translational response to stress in stress-sensitive CA3 neurons leading to persistent changes in gene expression, some of which mimic the transient effects of AS in control mice, while leaving in operation the immediate early gene response to AS.

Associations Between Maternal Caregiving and Child Indicators of Toxic Stress Among Multiethnic, Urban Families

INTRODUCTION

Our purpose was to examine associations between maternal caregiving and child indicators of toxic stress among multiethnic, urban families with children of early school age.

METHOD

We conducted an exploratory cross-sectional analysis of 54 maternal-child dyads. Mothers reported on parenting behaviors and parental reflective functioning (PRF). Child indicators of toxic stress included hair/salivary biomarkers, anthropometric characteristics, and maternally reported health and behavior.

RESULTS

Hostile/coercive parenting behaviors were associated with child externalizing behavioral problems (r = 0.43, p = .001, but lower interleukin (IL) 6 levels (r = 0.31, p = .03). High PRF was associated with fewer child emergency department visits (ρ = -0.43, p = .009), whereas impaired PRF was associated with more behavioral problems (ρ = 0.52, p < .0001).

DISCUSSION

PRF and supportive parenting behaviors may protect against toxic stress among vulnerable families, but additional research is needed to better understand these relationships. Resources are available to help clinicians screen for family risk factors and model responsive caregiving in pediatric settings.

Translating basic research knowledge on the biological embedding of early-life stress into novel approaches for the developmental programming of lifelong health

This review integrates scientific knowledge obtained over the past few decades on the biological mechanisms that contribute to the profound association between exposure to early adversity, including childhood trauma and prenatal stress, and the lifelong elevated risk to develop a broad range of diseases. We further discuss insights into gene-environment interactions moderating the association between early adversity and disease manifestation and we discuss the role of epigenetic and other molecular processes in the biological embedding of early adversity. Based on these findings, we propose potential mechanisms that may contribute to the intergenerational transmission of risk related to early adversity from the mother to the fetus. Finally, we argue that basic research knowledge on the biological embedding of early adversity must now be translated into novel intervention strategies that are mechanism-driven and sensitive to developmental timing. Indeed, to date, there are no diagnostic biomarkers of risk or mechanism-informed interventions that we can offer to victims of early adversity in order to efficiently prevent or reverse adverse health outcomes. Such translational efforts can be expected to have significant impact on both clinical practice and the public health system, and will promote precision medicine in pediatrics and across the lifespan.

Hippocampal volume and depression among young children

Clinical depression can occur in young children as early as age three. This very early onset variant of depression shows the same clinical features with developmental adjustments as depression that onsets later in life. One robust neural feature of adult depression is reduced hippocampal volume. We measured hippocampal volume in a sample of 35 children aged 4-7 who were either in a clinical trial for preschool onset depression or were recruited from the community. We used T1 MPRAGE acquisitions on a Siemen's Scanner, with Freesurfer 5.3 used to segment the hippocampus. Depression was measured using the K-SADS early childhood (K-SADS-EC) to create a dimensional depression severity score and the Child Behavior Checklist (CBCL) Depression T-Score. Multilevel models indicated that greater depression severity as measured by either the CBCL Depression Score or the K-SADS-EC was associated with lower hippocampal volume, even controlling for total gray matter, maternal depression, income-to-needs ratio, and stressful life events. These data indicate evidence for reduced hippocampal volume among children with PO-MDD who were more severely depressed. Findings are consistent with the idea that hippocampal volume reductions are an early occurring associated neural marker of MDD, particularly for more severe depression.

Tanycytes and the Control of Thyrotropin-Releasing Hormone Flux Into Portal Capillaries

Central and peripheral mechanisms that modulate energy intake, partition and expenditure determine energy homeostasis. Thyroid hormones (TH) regulate energy expenditure through the control of basal metabolic rate and thermogenesis; they also modulate food intake. TH concentrations are regulated by the hypothalamus-pituitary-thyroid (HPT) axis, and by transport and metabolism in blood and target tissues. In mammals, hypophysiotropic thyrotropin-releasing hormone (TRH) neurons of the paraventricular nucleus of the hypothalamus integrate energy-related information. They project to the external zone of the median eminence (ME), a brain circumventricular organ rich in neuron terminal varicosities and buttons, tanycytes, other glial cells and capillaries. These capillary vessels form a portal system that links the base of the hypothalamus with the anterior pituitary. Tanycytes of the medio-basal hypothalamus express a repertoire of proteins involved in transport, sensing, and metabolism of TH; among them is type 2 deiodinase, a source of 3,3',5-triiodo-L-thyronine necessary for negative feedback on TRH neurons. Tanycytes subtypes are distinguished by position and phenotype. The end-feet of β2-tanycytes intermingle with TRH varicosities and terminals in the external layer of the ME and terminate close to the ME capillaries. Besides type 2 deiodinase, β2-tanycytes express the TRH-degrading ectoenzyme (TRH-DE); this enzyme likely controls the amount of TRH entering portal vessels. TRH-DE is rapidly upregulated by TH, contributing to TH negative feedback on HPT axis. Alterations in energy balance also regulate the expression and activity of TRH-DE in the ME, making β2-tanycytes a hub for energy-related regulation of HPT axis activity. β2-tanycytes also express TRH-R1, which mediates positive effects of TRH on TRH-DE activity and the size of β2-tanycyte end-feet contacts with the basal lamina adjacent to ME capillaries. These end-feet associations with ME capillaries, and TRH-DE activity, appear to coordinately control HPT axis activity. Thus, down-stream of neuronal control of TRH release by action potentials arrival in the external layer of the median eminence, imbricated intercellular processes may coordinate the flux of TRH into the portal capillaries. In conclusion, β2-tanycytes appear as a critical cellular element for the somatic and post-secretory control of TRH flux into portal vessels, and HPT axis regulation in mammals.

Brexanolone, a neurosteroid antidepressant, vindicates the GABAergic deficit hypothesis of depression and may foster resilience

The GABAergic deficit hypothesis of depression states that a deficit of GABAergic transmission in defined neural circuits is causal for depression. Conversely, an enhancement of GABA transmission, including that triggered by selective serotonin reuptake inhibitors or ketamine, has antidepressant effects. Brexanolone, an intravenous formulation of the endogenous neurosteroid allopregnanolone, showed clinically significant antidepressant activity in postpartum depression. By allosterically enhancing GABA _A receptor function, the antidepressant activity of allopregnanolone is attributed to an increase in GABAergic inhibition. In addition, allopregnanolone may stabilize normal mood by decreasing the activity of stress-responsive dentate granule cells and thereby sustain resilience behavior. Therefore, allopregnanolone may augment and extend its antidepressant activity by fostering resilience. The recent structural resolution of the neurosteroid binding domain of GABA _A receptors will expedite the development of more selective ligands as a potential new class of central nervous system drugs.

The role of the genome in experience-dependent plasticity: Extending the analogy of the genomic action potential

Our past experiences shape our current and future behavior. These experiences must leave some enduring imprint on our brains, altering neural circuits that mediate behavior and contributing to our individual differences. As a framework for understanding how experiences might produce lasting changes in neural circuits, Clayton [D. F. Clayton, Neurobiol. Learn. Mem. 74, 185-216 (2000)] introduced the concept of the genomic action potential (gAP)-a structured genomic response in the brain to acute experience. Similar to the familiar electrophysiological action potential (eAP), the gAP also provides a means for integrating afferent patterns of activity but on a slower timescale and with longer-lasting effects. We revisit this concept in light of contemporary work on experience-dependent modification of neural circuits. We review the "Immediate Early Gene" (IEG) response, the starting point for understanding the gAP. We discuss evidence for its involvement in the encoding of experience to long-term memory across time and biological levels of organization ranging from individual cells to cell ensembles and whole organisms. We explore distinctions between memory encoding and homeostatic functions and consider the potential for perpetuation of the imprint of experience through epigenetic mechanisms. We describe a specific example of a gAP in humans linked to individual differences in the response to stress. Finally, we identify key objectives and new tools for continuing research in this area.

Early Developmental Stress Affects Subsequent Gene Expression Response to an Acute Stress in Atlantic Salmon: An Approach for Creating Robust Fish for Aquaculture?

Stress during early life has potential to program and alter the response to stressful events and metabolism in later life. Repeated short exposure of Atlantic salmon to cold water and air during embryonic (E), post-hatch (PH) or both phases of development (EPH) has been shown to alter the methylome and transcriptome and to affect growth performance during later life compared to untreated controls (CO). The aim of this study was to investigate how the transcriptome of these fish responds to subsequent acute stress at the start feeding stage, and to describe methylation differences that might steer these changes. EPH treated fish showed the strongest down-regulation of corticotropin releasing factor 1, up-regulation of glucocorticoid receptor and 3-oxo-5-alpha-steroid 4-dehydrogenase 2 gene expression and a suppressed cortisol response 3 hr after the acute stress, differences that could influence hormesis and be affecting how EPH fish cope and recover from the stress event. Growth hormone 2 and insulin-like growth factor 1 were more strongly down-regulated following acute stress in EPH treated fish relative to E, PH and CO fish. This indicates switching away from growth toward coping with stress following stressful events in EPH fish. Genes implicated in immune function such as major histocompatibility class 1A, T-cell receptor and toll-like receptor also responded to acute stress differently in EPH treated fish, indicating that repeated stresses during early life may affect robustness. Differential DNA methylation was detected in regions mapping <500 bases from genes differentially responding to acute stress suggesting the involvement of epigenetic mechanisms. Stress treatments applied during early development therefore have potential as a husbandry tool for boosting the productivity of aquaculture by affecting how fish respond to stresses at critical stages of production.

Adverse Childhood Experiences and Their Relation to Parenting Stress and Parenting Practices

The objective of this study was to understand the relationship between the early adverse childhood experiences (ACEs) of parents and their later parenting stress and practices. At the baseline visit of an 8-week course of cognitive behavioral therapy, parenting women completed the Parenting Stress Index-Short Form (PSI-SF) and the Positive Parenting Practices (PPP) scale. Linear regression procedures were used to assess the relationship between a parent's own early experience of ACEs and current parenting stress and practices, including if there was a dose-response relationship. For the PSI-SF, significant dose-response relationships were observed between ACEs and the PSI Total Stress score (p < 0.05) and the difficult child subscale (p < 0.05). Additionally, a relationship was suggested with the parental distress subscale (p < 0.10). No significant relationships were found between ACEs and the parent-child dysfunctional interaction subscale of the PSI-SF or the PPP scale. Given the association observed between ACEs and parenting stress, it is important that future psychosocial interventions and policy initiatives preventing ACEs are developed.

Cortisol levels before and after cognitive behavioural therapy in patients with eating disorders reporting childhood abuse: A follow-up study

The etiopathogenesis of eating disorders (EDs) is complex and still not well understood. Biological, psychological and environmental factors (e.g. childhood abuse) have all been considered to be involved in the onset and the persistence of EDs. The hypothalamic-pituitary-adrenal (HPA) axis is a relevant biological factor capable of influencing the onset and the course of EDs and not many information are available about the impact of a Cognitive Behavioral Therapy (CBT) on cortisol changes in EDs. The HPA-axis functioning has been evaluated before and after CBT in a group of patients with Anorexia Nervosa (n = 34) and Bulimia Nervosa (n = 35) according to the presence/absence of a history of sexual/physical abuse. At baseline, only patients reporting childhood abuse showed lower morning cortisol levels as compared with other patients of the same diagnostic group and Healthy Controls. After CBT, a variation of cortisol levels has been found only in patients without abuse, suggesting a role of childhood adversities in the persistence of HPA-axis alterations in Eating Disorders.

Hair cortisol, allostatic load, and depressive symptoms in Australian Aboriginal and Torres Strait Islander people

Chronic stress and adversity are associated with poor mental health and are thought to contribute to the existing mental health gap between Aboriginal and Torres Strait Islander people and other Australians. Hair cortisol and allostatic load (AL) are indices of sustained stress and may be mediators of the effects of stress on health. The aim of this study was to examine the relationship between hair cortisol, AL, and depressive symptoms. This cross-sectional study comprised 329 Aboriginal and Torres Strait Islander adolescents and adults recruited at two health screening programs operating in three communities in north Queensland. We measured hair cortisol and calculated an AL index from 10 biomarkers. We assessed depressive symptoms with a version of the Patient Health Questionnaire-9 adapted for Aboriginal and Torres Strait Islander people (aPHQ-9). We found differences in cortisol and AL between the screening programs and communities, which were not explained by depressive symptoms. Overall aPHQ-9 scores were unrelated to hair cortisol (p = .25 and p = .94) and AL (p = .30 and p = .88) when age, gender and smoking were taken into account. However, anhedonia (p = .007) and insomnia (p = .006) sub-scores were each significantly associated with AL in one study site. Our present data did not demonstrate overall associations of stress biomarkers and multisystem dysregulation with depressive symptoms, which suggests that the relationship between cumulative stress and depression may be better explained by other factors in this population. The specific association between anhedonia and insomnia with AL indicates that chronic multisystem dysregulation plays a role in these features of depression in this population. Lay summary Our study investigated the relationship between symptoms of depression and two biological pathways thought to mediate depression risk - the stress hormone cortisol and allostatic load (AL) - in an Australian Aboriginal and Torres Strait Islander population. Overall, cortisol and AL were unrelated to depression. However, AL was selectively associated with anhedonia (lack of motivation or drive) and sleep disturbances. These results suggest that metabolic dysregulation measured as AL may be relevant to the depression risk in this population.

The Association Between Affective Temperament Traits and Dopamine Genes in Obese Population

Studies indicate the heritable nature of affective temperament, which shows personality traits predisposing to the development of mental disorders. Dopaminergic gene polymorphisms such as DRD4, COMTVal158Met, and DAT1 have been linked to affective disorders in obesity. Due to possible correlation between the aforementioned polymorphisms and the affective temperament, the aim of our research was to investigate this connection in an obese population. The study enrolled 245 obese patients (178 females; 67 males). The affective temperament was assessed using the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego autoquestionnaire (TEMPS-A). Genetic polymorphisms of DAT1, COMTVal158Met and DRD4 were collected from peripheral blood sample and determined using a polymerase chain reaction (PCR). Only in COMT polymorphisms, the cyclothymic and irritable dimensions were significantly associated with Met/Val carriers (p = 0.04; p = 0.01). Another interesting finding was the correlation between the affective temperament and age in men and women. We assume that dopamine transmission in heterozygotes of COMT may determine the role of the affective temperament in obese persons. Dopaminergic transmission modulated by COMT may be responsible for a greater temperament expression in obese individuals. To our knowledge, this is the first study describing the role of affective temperament in the obese population, but more research is needed in this regard.

Transgenerational epigenetic influences of paternal environmental exposures on brain function and predisposition to psychiatric disorders

In recent years, striking new evidence has demonstrated non-genetic inheritance of acquired traits associated with parental environmental exposures. In particular, this transgenerational modulation of phenotypic traits is of direct relevance to psychiatric disorders, including depression, post-traumatic stress disorder, and other anxiety disorders. Here we review the recent progress in this field, with an emphasis on acquired traits of psychiatric illnesses transmitted epigenetically via the male lineage. We discuss the transgenerational effects of paternal exposure to stress vs. positive stimuli, such as exercise, and discuss their impact on the behavioral, affective and cognitive characteristics of their progeny. Furthermore, we review the recent evidence suggesting that these transgenerational effects are mediated by epigenetic mechanisms, including changes in DNA methylation and small non-coding RNAs in the sperm. We discuss the urgent need for more research exploring transgenerational epigenetic effects in animal models and human populations. These future studies may identify epigenetic mechanisms as potential contributors to the 'missing heritability' observed in genome-wide association studies of psychiatric illnesses and other human disorders. This exciting new field of transgenerational epigenomics will facilitate the development of novel strategies to predict, prevent and treat negative epigenetic consequences on offspring health, and psychiatric disorders in particular.

Exposure to enriched environment rescues anxiety-like behavior and miRNA deregulated expression induced by perinatal malnutrition while altering oligodendrocyte morphology

Maternal malnutrition is one of the major early-life adversities affecting the development of newborn's brain and is associated with an increased risk to acquire cognitive and emotional deficiencies later in life. Studies in rodents have demonstrated that exposure to an enriched environment (EE) can reverse the negative consequences of early adversities. However, rescue of emotional disorders caused by perinatal malnutrition and the mechanisms involved has not been determined. We hypothesized that exposure to an EE may attenuate the anxiety-like disorders observed in mice subjected to perinatal protein malnutrition and that this could be mediated by epigenetic mechanisms. Male CF-1 mice were subject to perinatal protein malnutrition until weaning and then exposed to an EE for 5 weeks after which small RNA-seq was performed. In parallel, dark-light box and elevated plus maze tests were conducted to evaluate anxiety traits. We found that exposure to an EE reverses the anxiety-like behavior in malnourished mice. This reversal is paralleled by the expression of three miRNAs that become dysregulated by perinatal malnutrition (miR-187-3p, miR-369-3p and miR-132-3p). The predicted mRNA targets of these miRNAs are mostly related to axon guidance pathway. Accordingly, we also found that perinatal malnutrition leads to reduction in the cingulum size and altered oligodendrocyte morphology. These results suggest that EE-rescue of anxiety disorders derived from perinatal malnutrition is mediated by the modulation of miRNAs associated with the regulation of genes involved in axonal guidance.

The hypothalamic-pituitary-adrenal axis in PTSD: Pathophysiology and treatment interventions

Questions of how altered functioning of the hypothalamic pituitary adrenal (HPA) axis contribute to the development and maintenance of posttraumatic stress disorder (PTSD) have been the focus of extensive animal and human research. As a rule, results have been inconsistent across studies, likely due to a variety of confounding variables that have received inadequate attention. Important confounding factors include the effects of early life stress, biological sex, and the glucocorticoid used for interventions. In this manuscript we review: 1) the literature on identified abnormalities of HPA axis function in PTSD, both in terms of basal functioning and as part of challenge paradigms; 2) the role of HPA axis function pre- and immediately post-trauma as a risk factor for PTSD development; 3) the impact of HPA axis genes' allelic variants and epigenetic modifications on PTSD risk; 4) the contributions of HPA axis components to fear learning and extinction; and 5) therapeutic manipulations of the HPA axis to both prevent and treat PTSD, including the role of glucocorticoids as part of medication enhanced psychotherapy.

Promoting the well-being of mothers with multidisciplinary psychosocial interventions in the perinatal period

BACKGROUND

Antenatal depressive and anxiety symptoms are common and may persist over time after delivery, with negative consequences on the mothers and their children. Evidence on the efficacy of psychological and pharmacological interventions during pregnancy aimed at preventing post-partum depression is controversial.

METHODS

A consecutive sample of 318 women presenting for scheduled obstetric visits during pregnancy was screened for risk factors and anxiety or depressive symptoms. Based on the screening results, women were classified into three groups at increasing risk of post-partum depression (PPD) and were offered different interventions.

RESULTS

Depressive or anxiety symptoms were found in 91 (28.6%) women, 89 (28.0%) had low risk of PPD and 138 (43.4%) had no risk of PPD. The multidisciplinary psychosocial interventions offered to women with clinical symptoms were well accepted, with an uptake of 76/91 (83.5%). Thirty-three women who did not improve with psychotherapy were offered sertraline or paroxetine as a second-line treatment: 7 accepted and 26 (78.8%) refused. Eleven women already on medication at baseline continued their treatment along with the MPI. The MPI interventions had some positive effects in terms of post-partum recovery, symptom reduction, and in preventing a new onset of depression. Among the 227 non-symptomatic during pregnancy, only 5 (2.2%) developed symptoms in the post-partum period. At 12 months post-partum, 84.6% of women who were symptomatic at 2 months post-partum recovered.

LIMITATIONS

Our results should be interpreted in light of important limitations, including the lack of a control group that was not offered the MPI, the lack of information on the reasons for refusal and discontinuation and on the number of psychotherapy sessions attended.

CONCLUSIONS

Our findings underscore the potential usefulness of MPI in recognizing early signs or symptoms during pregnancy and the advantage of building specific interventions for preventing post-natal depression. The MPI has positive effects on women with depressive or anxiety symptoms during pregnancy, that however did not exceed significantly those observed in women who refused the intervention. Thus, in the absence of a control group, our results are preliminary and warrant confirmation and testing in future randomized clinical trials.

Altered cellular immune reactivity in traumatized women with and without major depressive disorder

Alterations of the hypothalamic-pituitary-adrenal (HPA) axis such as altered glucocorticoid receptor sensitivity and increased immune reactivity might contribute to the pathogenesis of major depressive disorder (MDD). Exposure to adverse childhood experiences (ACE) precipitates vulnerability to MDD and might be associated with endocrine and immune alterations in the disorder. In order to disentangle the effects of ACE and MDD, we recruited 87 women: n = 23 with MDD and ACE as determined by clinical interview and questionnaires (Structured Clinical Interview for DSM-IV, Early Trauma Inventory, Childhood Trauma Questionnaire), n = 24 with MDD without ACE, n = 21 with ACE but no current or lifetime MDD, and n = 26 healthy women without either MDD or ACE. Glucocorticoid signaling and mitogen-stimulated proliferation were analyzed ex vivo in peripheral blood-derived mononuclear cells. Additionally, mRNA expression of the glucocorticoid and the mineralocorticoid receptor (GR / MR) was assessed. Peripheral GR sensitivity as well as GR and MR expression levels were not significantly different between groups. Women with ACE showed an increased immune response after mitogen stimulation independent of the presence of MDD. Our results provide evidence for a functionally altered ex-vivo immune response in cell cultures from women with a history of ACE. Thus, ACE might contribute to the pathogenesis of MDD through inflammatory pathways.

Social stability influences the association between adrenal responsiveness and hair cortisol concentrations in rhesus macaques

Hair cortisol concentrations are increasingly being used in both humans and nonhuman animals as a biomarker of chronic stress. However, many details regarding how hair cortisol concentrations relate to the dynamic activity and regulation of the HPA axis are still unknown. The current study explores 1) how the regulation of the HPA axis in infancy relates to hair cortisol concentrations (HCC) in infancy 2) whether this relationship persists into adulthood under conditions of social stability, and 3) how social instability impacts these relationships. All subjects were rhesus monkeys housed in large social groups at the California National Primate Research Center, and all had participated in a 25-hr. long BioBehavioral Assessment (BBA) at 3-4 months of age when four plasma samples were taken to assess HPA regulation, in particular cortisol responses to 1) 2-hour social separation and relocation, 2) sustained challenge, 3) dexamethasone and 4) ACTH administration. In Study 1, hair samples were collected at the end of the BBA testing from 25 infant rhesus monkeys from 2 different stable social groups. In Study 2, hair samples were obtained at three timepoints from 108 adults from 3 different stable social groups (1 in the Spring/Summer and 2 in the Fall/Winter) to examine the temporal stability of the relationship between HCC and HPA axis regulation. In Study 3, subjects included 31 infants and 33 adults from a single social group experiencing social instability following the same procedures as in Studies 1 and 2. Generalized linear models were used to determine if infants' HPA axis activity and regulation predicted HCC in infancy (Study 1), in adulthood with animals living in stable social conditions (Study 2) or in animals living in an unstable social group (Study 3). Results indicated that for both infants and adults living in stable social groups, HCC are associated with the adrenal response to ACTH in infancy. Samples collected in the winter also had higher HCC than those collected in summer. In the unstable social group, adult hair cortisol levels were higher than in the stable social groups. Additionally, there were no consistent relationships between HCC and infant HPA axis regulation among adults or infants living in a group experiencing social instability. These results suggest that the aspects of the HPA axis that drive HCC may differ depending on context. Under stable, non-stressed conditions there seems to be a trait-like association between adrenal responsivity and HCC in infancy and adulthood. However, this association may be reduced or eliminated under conditions of social stress.

Early Life Stress and Epigenetics in Late-onset Alzheimer's Dementia: A Systematic Review

Involvement of life stress in Late-Onset Alzheimer's Disease (LOAD) has been evinced in longitudinal cohort epidemiological studies, and endocrinologic evidence suggests involvements of catecholamine and corticosteroid systems in LOAD. Early Life Stress (ELS) rodent models have successfully demonstrated sequelae of maternal separation resulting in LOAD-analogous pathology, thereby supporting a role of insulin receptor signalling pertaining to GSK-3beta facilitated tau hyper-phosphorylation and amyloidogenic processing. Discussed are relevant ELS studies, and findings from three mitogen-activated protein kinase pathways (JNK/SAPK pathway, ERK pathway, p38/MAPK pathway) relevant for mediating environmental stresses. Further considered were the roles of autophagy impairment, neuroinflammation, and brain insulin resistance. For the meta-analytic evaluation, 224 candidate gene loci were extracted from reviews of animal studies of LOAD pathophysiological mechanisms, of which 60 had no positive results in human LOAD association studies. These loci were combined with 89 gene loci confirmed as LOAD risk genes in previous GWAS and WES. Of the 313 risk gene loci evaluated, there were 35 human reports on epigenomic modifications in terms of methylation or histone acetylation. 64 microRNA gene regulation mechanisms were published for the compiled loci. Genomic association studies support close relations of both noradrenergic and glucocorticoid systems with LOAD. For HPA involvement, a CRHR1 haplotype with MAPT was described, but further association of only HSD11B1 with LOAD found; however, association of FKBP1 and NC3R1 polymorphisms was documented in support of stress influence to LOAD. In the brain insulin system, IGF2R, INSR, INSRR, and plasticity regulator ARC, were associated with LOAD. Pertaining to compromised myelin stability in LOAD, relevant associations were found for BIN1, RELN, SORL1, SORCS1, CNP, MAG, and MOG. Regarding epigenetic modifications, both methylation variability and de-acetylation were reported for LOAD. The majority of up-to-date epigenomic findings include reported modifications in the well-known LOAD core pathology loci MAPT, BACE1, APP (with FOS, EGR1), PSEN1, PSEN2, and highlight a central role of BDNF. Pertaining to ELS, relevant loci are FKBP5, EGR1, GSK3B; critical roles of inflammation are indicated by CRP, TNFA, NFKB1 modifications; for cholesterol biosynthesis, DHCR24; for myelin stability BIN1, SORL1, CNP; pertaining to (epi)genetic mechanisms, hTERT, MBD2, DNMT1, MTHFR2. Findings on gene regulation were accumulated for BACE1, MAPK signalling, TLR4, BDNF, insulin signalling, with most reports for miR-132 and miR-27. Unclear in epigenomic studies remains the role of noradrenergic signalling, previously demonstrated by neuropathological findings of childhood nucleus caeruleus degeneration for LOAD tauopathy.

A study of the relationship between adverse childhood experiences, life events, and executive function among college students in China

Objective

The aim of this study was to investigate the effects of adverse childhood experiences and life events on the inhibitory control ability, cognitive flexibility, and working memory of college students.

Methods

The study involved testing the participants using the Adverse Childhood Experiences (ACEs) Questionnaire, the Adolescent Life Events Scale (Adolescent Self-rating Life Events Checklist, ASLEC), and the program of executive functions designed by E-prime software.

Results

The incidence rate of ACEs was 44.8%. ACEs, life events, and inhibition ability were found to have a significant correlation (r1 = 0.50, r1 = 0.47, p < 0.01). In the switching task, the reaction time of the ACEs group was longer than the reaction time of the non-ACEs group (t = − 2.55, p < 0.05). Low scorers in the ASLEC exhibited lesser reaction times than their high-scoring counterparts in the tasks related to inhibition, switching, and working memory experiments. The regression analysis results showed that ACEs and life events had a possibility rate of 56% in predicting inhibition ability.

Conclusions

The incidence of ACEs was found to be high, and cognitive flexibility is significantly influenced by ACEs. Life events have a significant impact on inhibition ability, cognitive flexibility, and working memory. ACEs and life events were found to be reliable predictors of inhibition ability.

Children's biobehavioral reactivity to challenge predicts DNA methylation in adolescence and emerging adulthood

A growing body of research has documented associations between adverse childhood environments and DNA methylation, highlighting epigenetic processes as potential mechanisms through which early external contexts influence health across the life course. The present study tested a complementary hypothesis: indicators of children's early internal, biological, and behavioral responses to stressful challenges may also be linked to stable patterns of DNA methylation later in life. Children's autonomic nervous system reactivity, temperament, and mental health symptoms were prospectively assessed from infancy through early childhood, and principal components analysis (PCA) was applied to derive composites of biological and behavioral reactivity. Buccal epithelial cells were collected from participants at 15 and 18 years of age. Findings revealed an association between early life biobehavioral inhibition/disinhibition and DNA methylation across many genes. Notably, reactive, inhibited children were found to have decreased DNA methylation of the DLX5 and IGF2 genes at both time points, as compared to non‐reactive, disinhibited children. Results of the present study are provisional but suggest that the gene's profile of DNA methylation may constitute a biomarker of normative or potentially pathological differences in reactivity. Overall, findings provide a foundation for future research to explore relations among epigenetic processes and differences in both individual‐level biobehavioral risk and qualities of the early, external childhood environment.

Profiling changes in cortical astroglial cells following chronic stress

Recent studies have suggested that cortical astroglia play an important role in depressive-like behaviors. Potential astroglial contributions have been proposed based on their known neuroplastic functions, such as glutamate recycling and synaptic plasticity. However, the specific mechanisms by which astroglial cells may contribute or protect against a depressive phenotype remain unknown. To delineate astroglial changes that accompany depressive-like behavior, we used astroglial-specific bacTRAP mice exposed to chronic variable stress (CVS) and profiled the astroglial translatome using translating ribosome affinity purification (TRAP) in conjunction with RNAseq. As expected, CVS significantly increased anxiety- and depressive-like behaviors and corticosterone levels and decreased GFAP expression in astroglia, although this did not reflect a change in the total number of astroglial cells. TRAPseq results showed that CVS decreased genes associated with astroglial plasticity: RhoGTPases, growth factor signaling, and transcription regulation, and increased genes associated with the formation of extracellular matrices such as perineuronal nets (PNNs). PNNs inhibit neuroplasticity and astroglia contribute to the formation, organization, and maintenance of PNNs. To validate our TRAPseq findings, we showed an increase in PNNs following CVS. Degradation of PNNs in the prefrontal cortex of mice exposed to CVS reversed the CVS-induced behavioral phenotype in the forced swim test. These data lend further support to the neuroplasticity hypothesis of depressive behaviors and, in particular, extend this hypothesis beyond neuronal plasticity to include an overall decrease in genes associated with cortical astroglial plasticity following CVS. Further studies will be needed to assess the antidepressant potential of directly targeting astroglial cell function in models of depression.

Sex-specific epigenetic mediators between early life social disadvantage and adulthood BMI

AIM

The objective of this study was to identify potential epigenetic mediating pathways linking early life social disadvantage (ELSD) to adulthood BMI.

METHODS

Sex-specific epigenome-wide two-stage mediation analyses were conducted in blood and adipose tissue, and mediation estimates were obtained using cross-product mediation analysis. Pathway analyses were conducted using GREAT software (Bejerano Lab, CA, USA).

RESULTS

Candidate mediation CpG sites were identified in adipose tissue, but not blood, and were sex-specific. Significant mediation sites in females included CpG loci in genes: PKHG1, BCAR3, ADAM5P, PIEZO1, FGFRL1, FASN and DPP9, among others. Pathway analyses revealed evidence of enrichment for processes associated with TFG-β signaling and immunologic signatures. In males, significant mediation loci included sites in MAP3K5 and RPTOR, which have previously been associated with adipogenesis, inflammation and insulin resistance.

CONCLUSION

Our findings provide supportive evidence for the mediating role of epigenetic mechanisms in the effect of early life social disadvantage on adulthood BMI.

Glucocorticoid-endocannabinoid uncoupling mediates fear suppression deficits after early - Life stress

Early-life stress (ELS) creates life-long vulnerability to stress-related anxiety disorders through altering stress and fear systems in the brain. The endocannabinoid system has emerged as an important regulator of the stress response through a crosstalk with the glucocorticoid system, yet whether it plays a role in the persistent effects of ELS remains unanswered. By combining, behavioral, pharmacological and biochemical approaches in adult male rats, we examined the impact of ELS on the regulation of endocannabinoid function by stress and glucocorticoids. We employed a postnatal limited-nesting/bedding induced ELS between postnatal days 2-9 in rats. Exposure to postnatal ELS compromised the ability of both acute stress and glucocorticoid administration to mobilize the endocannabinoid ligand 2-arachidonoyl glycerol (2-AG) in the hippocampus of adult male rats. These findings suggest that ELS compromises the coupling of the glucocorticoid and endocannabinoid systems in the hippocampus. Since 2-AG signaling is essential in mediating glucocorticoid-induced suppression of fear recall, we further examined the impact of ELS on the ability of glucocorticoids to suppress fear memory recall. While ELS did not affect normative fear recall, it impaired the ability of glucocorticoids to dampen fear recall. Notably, bypassing glucocorticoids and directly amplifying hippocampal 2-AG signaling with a monoacyl glycerol lipase inhibitor produced a suppression of fear memory recall in animals exposed to ELS. These findings suggest that ELS results in an uncoupling of glucocorticoid-endocannabinoid signaling in the hippocampus, which, in turn, relates to alterations in stress regulation of memory recall. These data provide compelling evidence that ELS-induced deficits in the glucocorticoid-endocannabinoid coupling following stress could predispose susceptibility to stress-related psychopathology.

Use of Unpalatable Forages by Ruminants: The Influence of Experience with the Biophysical and Social Environment

Unpalatable forage resources (low nutrient density, potentially toxic metabolites) are widespread and represent a challenge for ruminant nutrition, health, and welfare. Our objective was to synthesize the role of biophysical and social experience on the use of unpalatable forages by ruminants, and highlight derived behavioural solutions for the well-being of soils, plants, and animals. Environmental experiences early in life modulate gene expression and promote learning, which alters morpho-physiological and psychological mechanisms that modify behavioural responses and change food and habitat selection. In this process, ruminants can become better adapted to the habitat where they are reared. Moreover, experiential learning provides flexibility in diet selection, which is critical for changing foraging environments. Learned associations between unpalatable and palatable foods, if ingested in appropriate amounts, sequence, and close temporal association, induce the development of preference for the former type of food. In this way, a more uniform use of resources can be achieved from the landscape level down to the individual plant, with the associated benefits to ecosystem integrity and stability. Ruminants can also learn the medicinal benefits of ingesting foods with toxins (e.g., condensed tannins and saponins with antiparasitic properties). This knowledge on behavioural processes can be translated into behavioural applications that provide low-cost solutions to many challenges that producers face in managing sustainable livestock production systems.

Stress Response Modulation Underlying the Psychobiology of Resilience

PURPOSE OF REVIEW

This review focuses on the relationship between resilience and the ability to effectively modulate the stress response. Neurobiological and behavioral responses to stress are highly variable. Exposure to a similar stressor can lead to heterogeneous outcomes-manifesting psychopathology in one individual, but having minimal effect, or even enhancing resilience, in another. We highlight aspects of stress response modulation related to early life development and epigenetics, selected neurobiological and neurochemical systems, and a number of emotional, cognitive, psychosocial, and behavioral factors important in resilience. We also briefly discuss interventions with potential to build and promote resilience.

RECENT FINDINGS

Throughout this review, we include evidence from recent preclinical and clinical studies relevant to the psychobiology of resilient stress response modulation. Effective modulation of the stress response is an essential component of resilience and is dependent on a complex interplay of neurobiological and behavioral factors.

Early-Life Stressors, Personality Development, and Fast Life Strategies: An Evolutionary Perspective on Malevolent Personality Features

Life history theory posits that behavioral adaptation to various environmental (ecological and/or social) conditions encountered during childhood is regulated by a wide variety of different traits resulting in various behavioral strategies. Unpredictable and harsh conditions tend to produce fast life history strategies, characterized by early maturation, a higher number of sexual partners to whom one is less attached, and less parenting of offspring. Unpredictability and harshness not only affects dispositional social and emotional functioning, but may also promote the development of personality traits linked to higher rates of instability in social relationships or more self-interested behavior. Similarly, detrimental childhood experiences, such as poor parental care or high parent-child conflict, affect personality development and may create a more distrustful, malicious interpersonal style. The aim of this brief review is to survey and summarize findings on the impact of negative early-life experiences on the development of personality and fast life history strategies. By demonstrating that there are parallels in adaptations to adversity in these two domains, we hope to lend weight to current and future attempts to provide a comprehensive insight of personality traits and functions at the ultimate and proximate levels.

Molecular Characterization of GABA-A Receptor Subunit Diversity within Major Peripheral Organs and Their Plasticity in Response to Early Life Psychosocial Stress

Gamma aminobutyric acid (GABA) subtype A receptors (GABA_ARs) are integral membrane ion channels composed of five individual proteins or subunits. Up to 19 different GABA_AR subunits (α1–6, β1–3, γ1–3, δ, ε, θ, π, and ρ1–3) have been identified, resulting in anatomically, physiologically, and pharmacologically distinct multiple receptor subtypes, and therefore GABA-mediated inhibition, across the central nervous system (CNS). Additionally, GABA_AR-modulating drugs are important tools in clinical medicine, although their use is limited by adverse effects. While significant advances have been made in terms of characterizing the GABA_AR system within the brain, relatively less is known about the molecular phenotypes within the peripheral nervous system of major organ systems. This represents a potentially missed therapeutic opportunity in terms of utilizing or repurposing clinically available GABA_AR drugs, as well as promising research compounds discarded due to their poor CNS penetrance, for the treatment of peripheral disorders. In addition, a broader understanding of the peripheral GABA_AR subtype repertoires will contribute to the design of therapies which minimize peripheral side-effects when treating CNS disorders. We have recently provided a high resolution molecular and function characterization of the GABA_ARs within the enteric nervous system of the mouse colon. In this study, the aim was to determine the constituent GABA_AR subunit expression profiles of the mouse bladder, heart, liver, kidney, lung, and stomach, using reverse transcription polymerase chain reaction and western blotting with brain as control. The data indicate that while some subunits are expressed widely across various organs (α3–5), others are restricted to individual organs (γ2, only stomach). Furthermore, we demonstrate complex organ-specific developmental expression plasticity of the transporters which determine the chloride gradient within cells, and therefore whether GABA_AR activation has a depolarizing or hyperpolarizing effect. Finally, we demonstrate that prior exposure to early life psychosocial stress induces significant changes in peripheral GABA_AR subunit expression and chloride transporters, in an organ- and subunit-specific manner. Collectively, the data demonstrate the molecular diversity of the peripheral GABA_AR system and how this changes dynamically in response to life experience. This provides a molecular platform for functional analyses of the GABA–GABA_AR system in health, and in diseases affecting various peripheral organs.