Prenatal stress induced chromatin remodeling and risk of psychopathology in adulthood

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response. Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region-specific, particularly involving the corticolimbic system, including the ventral tegmental area, nucleus accumbens, prefrontal cortex, amygdala, and hippocampus. Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology. In this review, we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression. We focused on associated molecular pathways and neural circuits, with special attention to the brain-derived neurotrophic factor-tropomyosin receptor kinase B signaling pathway and the ventral tegmental area-nucleus accumbens dopamine circuit. We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature, severity, and duration of stress, especially in the above-mentioned brain regions of the corticolimbic system. Therefore, BDNF might be a biological indicator regulating stress-related processes in various brain regions.

Prenatal stress impacts foetal neurodevelopment: Temporal windows of gestational vulnerability

Prenatal maternal stressors ranging in severity from everyday occurrences/hassles to the experience of traumatic events negatively impact neurodevelopment, increasing the risk for the onset of psychopathology in the offspring. Notably, the timing of prenatal stress exposure plays a critical role in determining the nature and severity of subsequent neurodevelopmental outcomes. In this review, we evaluate the empirical evidence regarding temporal windows of heightened vulnerability to prenatal stress with respect to motor, cognitive, language, and behavioural development in both human and animal studies. We also explore potential temporal windows whereby several mechanisms may mediate prenatal stress-induced neurodevelopmental effects, namely, excessive hypothalamic-pituitary-adrenal axis activity, altered serotonin signalling and sympathetic-adrenal-medullary system, changes in placental function, immune system dysregulation, and alterations of the gut microbiota. While broadly defined developmental windows are apparent for specific psychopathological outcomes, inconsistencies arise when more complex cognitive and behavioural outcomes are considered. Novel approaches to track molecular markers reflective of the underlying aetiologies throughout gestation to identify tractable biomolecular signatures corresponding to critical vulnerability periods are urgently required.

Epigenetics of prenatal stress in humans: the current research landscape

Fetal exposure to prenatal stress can have significant consequences on short- and long-term health. Epigenetic mechanisms, especially DNA methylation (DNAm), are a possible process how these adverse environmental events could be biologically embedded. We evaluated candidate gene as well as epigenome-wide association studies associating prenatal stress and DNAm changes in peripheral tissues; however, most of these findings lack robust replication. Prenatal stress-associated epigenetic changes have also been linked to child health including internalizing problems, neurobehavioral outcomes and stress reactivity. Future studies should focus on refined measurement and definition of prenatal stress and its timing, ideally also incorporating genomic as well as longitudinal information. This will provide further opportunities to enhance our understanding of the biological embedding of prenatal stress exposure.

D1R-5-HT2AR Uncoupling Reduces Depressive Behaviours via HDAC Signalling

Dopamine and serotonin signalling are associated with major depressive disorder, which is a prevalent life-threatening illness worldwide. Numerous FDA-approved dopamine/serotonin signalling-modifying drugs are available but are associated with concurrent side effects and limited efficacy. Thus, identifying and targeting their signalling pathway is crucial for improving depression treatment. Here, we determined that serotonin receptor 2A (5-HT2AR) abundantly forms a protein complex with dopamine receptor 1 (D1R) in high abundance via its carboxy-terminus in the brains of mice subjected to various chronic stress paradigms. Furthermore, the D1R/5-HT2AR interaction elicited CREB/ERK/AKT modulation during synaptic regulation. An interfering peptide (TAT-5-HT2AR-SV) agitated the D1R/5-HT2AR interaction and attenuated depressive symptoms accompanied by CREB/ERK molecule costimulation. Interestingly, HDAC antagonism but not TrkB antagonism reversed the antidepressant effect of competitive peptides. These findings revealed a novel D1R/5-HT2AR heteroreceptor complex mechanism in the pathophysiology of depression, and their uncoupling ameliorates depressive-like behaviours through HDAC-, and not BDNF-, dependent mechanisms.

Dissecting early life stress-induced adolescent depression through epigenomic approach

Early life stress (ELS), such as abuse and neglect during childhood, can lead to psychiatric disorders in later life. Previous studies have suggested that ELS can cause profound changes in gene expression through epigenetic mechanisms, which can lead to psychiatric disorders in adulthood; however, studies on epigenetic modifications associated with ELS and psychiatric disorders in adolescents are limited. Moreover, how these epigenetic modifications can lead to psychiatric disorders in adolescents is not fully understood. Commonly, DNA methylation, histone modification, and the regulation of noncoding RNAs have been attributed to the reprogramming of epigenetic profiling associated with ELS. Although only a few studies have attempted to examine epigenetic modifications in adolescents with ELS, existing evidence suggests that there are commonalities and differences in epigenetic profiling between adolescents and adults. In addition, epigenetic modifications are sex-dependent and are influenced by the type of ELS. In this review, we have critically evaluated the current evidence on epigenetic modifications in adolescents with ELS, particularly DNA methylation and the expression of microRNAs in both preclinical models and humans. We have also clarified the impact of ELS on psychiatric disorders in adolescents to predict the development of neuropsychiatric disorders and to prevent and recover these disorders through personalized medicine.

Epigenetics as a Biomarker for Early-Life Environmental Exposure

PURPOSE OF REVIEW

There is interest in evaluating the developmental origins of health and disease (DOHaD) which emphasizes the role of prenatal and early-life environments on non-communicable health outcomes throughout the life course. The ability to rigorously assess and identify early-life risk factors for later health outcomes, including those with childhood onset, in large population samples is often limited due to measurement challenges such as impractical costs associated with prospective studies with a long follow-up duration, short half-lives for some environmental toxicants, and lack of biomarkers that capture inter-individual differences in biologic response to external environments.

RECENT FINDINGS

Epigenomic patterns, and DNA methylation in particular, have emerged as a potential objective biomarker to address some of these study design and exposure measurement challenges. In this article, we summarize the literature to date on epigenetic changes associated with specific prenatal and early-life exposure domains as well as exposure mixtures in human observational studies and their biomarker potential. Additionally, we highlight evidence for other types of epigenetic patterns to serve as exposure biomarkers. Evidence strongly supports epigenomic biomarkers of exposure that are detectable across the lifespan and across a range of exposure domains. Current and future areas of research in this field seek to expand these lines of evidence to other environmental exposures, to determine their specificity, and to develop predictive algorithms and methylation scores that can be used to evaluate early-life risk factors for health outcomes across the life span.

Maternal-fetal stress and DNA methylation signatures in neonatal saliva: an epigenome-wide association study

BACKGROUND

Maternal stress before, during and after pregnancy has profound effects on the development and lifelong function of the infant's neurocognitive development. We hypothesized that the programming of the central nervous system (CNS), hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS) induced by prenatal stress (PS) is reflected in electrophysiological and epigenetic biomarkers. In this study, we aimed to find noninvasive epigenetic biomarkers of PS in the newborn salivary DNA.

RESULTS

A total of 728 pregnant women were screened for stress exposure using Cohen Perceived Stress Scale (PSS), 164 women were enrolled, and 114 dyads were analyzed. Prenatal Distress Questionnaire (PDQ) was also administered to assess specific pregnancy worries. Transabdominal fetal electrocardiograms (taECG) were recorded to derive coupling between maternal and fetal heart rates resulting in a 'Fetal Stress Index' (FSI). Upon delivery, we collected maternal hair strands for cortisol measurements and newborn's saliva for epigenetic analyses. DNA was extracted from saliva samples, and DNA methylation was measured using EPIC BeadChip array (850 k CpG sites). Linear regression was used to identify associations between PSS/PDQ/FSI/Cortisol and DNA methylation. We found epigenome-wide significant associations for 5 CpG with PDQ and cortisol at FDR < 5%. Three CpGs were annotated to genes (Illumina Gene annotation file): YAP1, TOMM20 and CSMD1, and two CpGs were located approximately lay at 50 kb from SSBP4 and SCAMP1. In addition, two differentiated methylation regions (DMR) related to maternal stress measures PDQ and cortisol were found: DAXX and ARL4D.

CONCLUSIONS

Genes annotated to these CpGs were found to be involved in secretion and transportation, nuclear signaling, Hippo signaling pathways, apoptosis, intracellular trafficking and neuronal signaling. Moreover, some CpGs are annotated to genes related to autism, post-traumatic stress disorder (PTSD) and schizophrenia. However, our results should be viewed as hypothesis generating until replicated in a larger sample. Early assessment of such noninvasive PS biomarkers will allow timelier detection of babies at risk and a more effective allocation of resources for early intervention programs to improve child development. A biomarker-guided early intervention strategy is the first step in the prevention of future health problems, reducing their personal and societal impact.

Antidepressant Active Ingredients From Chinese Traditional Herb Panax Notoginseng: A Pharmacological Mechanism Review

Depression is one of the most common mental illnesses in the world and is highly disabling, lethal, and seriously endangers social stability. The side effects of clinical drugs used to treat depression are obvious, and the onset time is longer. Therefore, there is a great demand for antidepressant drugs with better curative effects, fewer side effects, and shorter onset time. Panax notoginseng, a Chinese herbal medication, has been used to treat depression for thousands of years and shown to have a therapeutic effect on depression. This review surveyed PubMed’s most recent 20 years of research on Panax notoginseng’s use for treating depression. We mainly highlight animal model research and outlined the pathways influenced by medicines. We provide a narrative review of recent empirical evidence of the anti-depressive effects of Panax Notoginseng and novel ideas for developing innovative clinical antidepressants with fewer side effects.

Placental CRH as a Signal of Pregnancy Adversity and Impact on Fetal Neurodevelopment

Early life is a period of considerable plasticity and vulnerability and insults during that period can disrupt the homeostatic equilibrium of the developing organism, resulting in adverse developmental programming and enhanced susceptibility to disease. Fetal exposure to prenatal stress can impede optimum brain development and deranged mother's hypothalamic-pituitary-adrenal axis (HPA axis) stress responses can alter the neurodevelopmental trajectories of the offspring. Corticotropin-releasing hormone (CRH) and glucocorticoids, regulate fetal neurogenesis and while CRH exerts neuroprotective actions, increased levels of stress hormones have been associated with fetal brain structural alterations such as reduced cortical volume, impoverishment of neuronal density in the limbic brain areas and alterations in neuronal circuitry, synaptic plasticity, neurotransmission and G-protein coupled receptor (GPCR) signalling. Emerging evidence highlight the role of epigenetic changes in fetal brain programming, as stress-induced methylation of genes encoding molecules that are implicated in HPA axis and major neurodevelopmental processes. These serve as molecular memories and have been associated with long term modifications of the offspring's stress regulatory system and increased susceptibility to psychosomatic disorders later in life. This review summarises our current understanding on the roles of CRH and other mediators of stress responses on fetal neurodevelopment.