Models of Intergenerational and Transgenerational Transmission of Risk for Psychopathology in Mice

Epigenetic mechanisms linking early-life adversities and mental health

Early-life adversities, whether prenatal or postnatal exposure, have been linked to adverse mental health outcomes later in life increasing the risk of several psychiatric disorders. Research on its neurobiological consequences demonstrated an association between exposure to adversities and persistent alterations in the structure, function, and connectivity of the brain. Consistent evidence supports the idea that regulation of gene expression through epigenetic mechanisms are involved in embedding the impact of early-life experiences in the genome and mediate between social environments and later behavioral phenotypes. In addition, studies from rodent models and humans suggest that these experiences and the acquired risk factors can be transmitted through epigenetic mechanisms to offspring and the following generations potentially contributing to a cycle of disease or disease risk. However, one of the important aspects of epigenetic mechanisms, unlike genetic sequences that are fixed and unchangeable, is that although the epigenetic markings are long-lasting, they are nevertheless potentially reversible. In this review, we summarize our current understanding of the epigenetic mechanisms involved in the mental health consequences derived from early-life exposure to malnutrition, maltreatment and poverty, adversities with huge and pervasive impact on mental health. We also discuss the evidence about transgenerational epigenetic inheritance in mammals and experimental data suggesting that suitable social and pharmacological interventions could reverse adverse epigenetic modifications induced by early-life negative social experiences. In this regard, these studies must be accompanied by efforts to determine the causes that promote these adversities and that result in health inequity in the population.

The microbiota and T cells non-genetically modulate inherited phenotypes transgenerationally

The host-microbiota relationship has evolved to shape mammalian physiology, including immunity, metabolism, and development. Germ-free models are widely used to study microbial effects on host processes such as immunity. Here, we find that both germ-free and T cell-deficient mice exhibit a robust sebum secretion defect persisting across multiple generations despite microbial colonization and T cell repletion. These phenotypes are inherited by progeny conceived during in vitro fertilization using germ-free sperm and eggs, demonstrating that non-genetic information in the gametes is required for microbial-dependent phenotypic transmission. Accordingly, gene expression in early embryos derived from gametes from germ-free or T cell-deficient mice is strikingly and similarly altered. Our findings demonstrate that microbial- and immune-dependent regulation of non-genetic information in the gametes can transmit inherited phenotypes transgenerationally in mice. This mechanism could rapidly generate phenotypic diversity to enhance host adaptation to environmental perturbations.

Parent Psychopathology and Behavioral Effects on Child Brain-Symptom Networks in the ABCD Study

OBJECTIVE

Parents play a notable role in the development of child psychopathology. In this study, we investigated the role of parent psychopathology and behaviors on child brain-symptom networks to understand the role of intergenerational transmission of psychopathology. Few studies have documented the interaction of child psychopathology, parent psychopathology, and child neuroimaging.

METHOD

We used the baseline cohort of the Adolescent Brain Cognitive Development Study (N = 7,151, female-at-birth = 3,619, aged 9-11 years) to derive brain-symptom networks using sparse canonical correlation analysis with the Child Behavior Checklist and resting-state functional magnetic resonance imaging. We then correlated parent psychopathology symptoms and parental behaviors with child brain-symptom networks. Finally, we used the significant correlations to understand, using the mediation R package, whether parent behaviors mediated the effect of parent psychopathology on child brain connectivity.

RESULTS

We observed 3 brain-symptom networks correlated with externalizing (r = 0.19, internalizing (r = 0.17), and neurodevelopmental symptoms (r = 0.18). These corresponded to differences in connectivity between the default mode-default mode, default mode-control, and visual-visual canonical networks. We further detected aspects of parental psychopathology, including personal strength, thought problems, and rule-breaking symptoms to be associated with child brain connectivity. Finally, we found that parental behaviors and symptoms mediate each other's relationship to child brain connectivity.

CONCLUSION

The current study suggests that positive parental behaviors can relieve potentially detrimental effects of parental psychopathology, and vice versa, on symptom-correlated child brain connectivity. Altogether, these results provide a framework for future research and potential targets for parents who experience mental health symptoms to help mitigate potential intergenerational transmission of mental illness.

Neonatal Nucleus Accumbens Microstructure Modulates Individual Susceptibility to Preconception Maternal Stress in Relation to Externalizing Behaviors

OBJECTIVE

Maternal stress influences in utero brain development and is a modifiable risk factor for offspring psychopathologies. Reward circuitry dysfunction underlies various internalizing and externalizing psychopathologies. This study examined (1) the association between maternal stress and microstructural characteristics of the neonatal nucleus accumbens (NAcc), a major node of the reward circuitry, and (2) whether neonatal NAcc microstructure modulates individual susceptibility to maternal stress in relation to childhood behavioral problems.

METHOD

K-means longitudinal cluster analysis was performed to determine trajectories of maternal stress measures (Perceived Stress Scale [PSS], hair cortisol) from preconception to the third trimester. Neonatal NAcc microstructural measures (orientation density index [ODI] and intracellular volume fraction [ICVF]) were compared across trajectories. We then examined the interaction between maternal stress and neonatal NAcc microstructure on child internalizing and externalizing behaviors, assessed between ages 3 and 4 years.

RESULTS

Two trajectories of maternal stress magnitude ("low"/"high") were identified for both PSS (n = 287) and hair cortisol (n = 336). Right neonatal NAcc ODI (rNAcc-ODI) was significantly lower in "low" relative to "high" PSS trajectories (n = 77, p = .04). PSS at preconception had the strongest association with rNAcc-ODI (r = 0.293, p = .029). No differences in NAcc microstructure were found between hair cortisol trajectories. A significant interaction between preconception PSS and rNAcc-ODI on externalizing behavior was observed (n = 47, p = .047).

CONCLUSION

Our study showed that the preconception period contributes to in utero NAcc development, and that NAcc microstructure modulates individual susceptibility to preconception maternal stress in relation to externalizing problems.

Pathways and processes to the embodiment of historical trauma secondary to settler colonialism

AIM(S)

This discursive article aims to examine how systemic factors of settler colonialism influence health outcomes among Indigenous peoples in the United States through pathways and processes that may lead to the embodiment of historical trauma.

DESIGN

Discursive paper.

METHODS

We completed a comprehensive search of empirical and grey literature between September 2022 and January 2023 in PubMed, CINAHL and Google Scholar. Using these articles as a foundation, we explored factors related to the pathways and processes leading to the embodiment of historical trauma rooted in settler colonialism.

RESULTS

A conceptual framework of the pathways and processes of the embodiment of historical trauma secondary to settler colonialism was developed, and is presented.

CONCLUSION

The societal and historical context for Indigenous peoples includes harmful settler colonial structures and ideologies, resulting in stressors and historical trauma that impact health outcomes and disparities through the phenomenon of the process of embodiment.

IMPLICATIONS FOR NURSING

To provide holistic nursing care, nurses must be aware of settler colonialism as a determinant of health. They must be attuned to the pathways and processes through which settler colonial exposures may impact health among Indigenous peoples. Nurses must challenge existing structural inequities to advance health equity and social justice.

Enhanced harm detection following maternal separation: Transgenerational transmission and reversibility by inhaled amiloride

Early-life adversities are associated with altered defensive responses. Here, we demonstrate that the repeated cross-fostering (RCF) paradigm of early maternal separation is associated with enhancements of distinct homeostatic reactions: hyperventilation in response to hypercapnia and nociceptive sensitivity, among the first generation of RCF-exposed animals, as well as among two successive generations of their normally reared offspring, through matrilineal transmission. Parallel enhancements of acid-sensing ion channel 1 (ASIC1), ASIC2, and ASIC3 messenger RNA transcripts were detected transgenerationally in central neurons, in the medulla oblongata, and in periaqueductal gray matter of RCF-lineage animals. A single, nebulized dose of the ASIC-antagonist amiloride renormalized respiratory and nociceptive responsiveness across the entire RCF lineage. These findings reveal how, following an early-life adversity, a biological memory reducible to a molecular sensor unfolds, shaping adaptation mechanisms over three generations. Our findings are entwined with multiple correlates of human anxiety and pain conditions and suggest nebulized amiloride as a therapeutic avenue.

Bedside to bench: the outlook for psychedelic research

There has recently been a resurgence of interest in psychedelic compounds based on studies demonstrating their potential therapeutic applications in treating post-traumatic stress disorder, substance abuse disorders, and treatment-resistant depression. Despite promising efficacy observed in some clinical trials, the full range of biological effects and mechanism(s) of action of these compounds have yet to be fully established. Indeed, most studies to date have focused on assessing the psychological mechanisms of psychedelics, often neglecting the non-psychological modes of action. However, it is important to understand that psychedelics may mediate their therapeutic effects through multi-faceted mechanisms, such as the modulation of brain network activity, neuronal plasticity, neuroendocrine function, glial cell regulation, epigenetic processes, and the gut-brain axis. This review provides a framework supporting the implementation of a multi-faceted approach, incorporating in silico, in vitro and in vivo modeling, to aid in the comprehensive understanding of the physiological effects of psychedelics and their potential for clinical application beyond the treatment of psychiatric disorders. We also provide an overview of the literature supporting the potential utility of psychedelics for the treatment of brain injury (e.g., stroke and traumatic brain injury), neurodegenerative diseases (e.g., Parkinson's and Alzheimer's diseases), and gut-brain axis dysfunction associated with psychiatric disorders (e.g., generalized anxiety disorder and major depressive disorder). To move the field forward, we outline advantageous experimental frameworks to explore these and other novel applications for psychedelics.

Plant transcriptional memory and associated mechanism of abiotic stress tolerance

Plants face various adverse environmental conditions, particularly with the ongoing changes in global climate, which drastically affect the growth, development and productivity of crops. To cope with these stresses, plants have evolved complex mechanisms, and one of the crucial ways is to develop transcriptional memories from stress exposure. This induced learning enables plants to better and more strongly restart the response and adaptation mechanism to stress when similar or dissimilar stresses reoccur. Understanding the molecular mechanism behind plant transcriptional memory of stress can provide a theoretical basis for breeding stress-tolerant crops with resilience to future climates. Here we review the recent research progress on the transcriptional memory of plants under various stresses and the applications of underlying mechanisms for sustainable agricultural production. We propose that a thorough understanding of plant transcriptional memory is crucial for both agronomic management and resistant breeding, and thus may help to improve agricultural yield and quality under changing climatic conditions.

Intergenerational and transgenerational effects of drought stress on winter wheat (Triticum aestivum L.)

The environments where the progenitors are grown have the potential to affect the expression of traits in their offspring. Currently, there are various hypotheses regarding the evolutionary and ecological importance of stress memory effects. There is uncertainty regarding its occurrence, persistence, predictability, and adaptive value. In this study, 15 winter wheat cultivars were grown under drought and well-watered (control) treatments for two seasons to produce seeds with all possible combinations of drought exposure histories. A comprehensive analysis to estimate transgenerational (grandparental effects), intergenerational (parental effects), and their combined memory effects on offspring traits under both control and drought moisture treatments, was performed. There were significant memory effects in most of the evaluated traits ranging from +787% to -39.0% changes in both seed quality and plant traits. The expression of stress memory was highly dependent on the generation and number of exposures, traits, and seasons. Under drought treatment, the combination of grandparental and parental stress memories was additive in all traits, but their strengths were variable when considered separately. Stress memory enhanced the performance of offspring under similar stressful conditions: increased plant height, above-ground biomass, number of grains per plant, grain weight per plant and water potential. This study offers valuable new insights into the occurrence of drought stress memory, the complexities of the effects, possible physiological and metabolic alterations explaining the detected differences, and impacts toward a clearer understanding of their generation and context-dependency.

Attachment and family functioning across three generations

The present study explores the transmission of attachment and family functioning across three generations. It is based on a sample of 460 female emerging adults (aged 18-26), their mothers (N = 440), fathers (N = 368), maternal grandmothers (N = 224), and maternal grandfathers (N = 113). Participants self-assessed their attachment anxiety and avoidance using the Relationship Style Questionnaire and evaluated the functioning of their families of origin using the Family Adaptation and Cohesion Scale-IV. The results reveal two mechanisms, both of which have a small but significant effect on the development of attachment across generations. The first operates via direct trans-generational transmission of attachment from parent to child, mainly involving the mother-child dyad, while the second operates through primary family functioning, especially balanced family cohesion, but also enmeshment and chaos in the case of attachment avoidance. The findings highlight the importance of including content related to attachment and family functioning in intervention programs.

Social deficits in mice prenatally exposed to valproic acid are intergenerationally inherited and rescued by social enrichment

Intergenerational transmission of the effects of environmental factors on brain function and behavior can occur through epigenetic mechanisms. Valproic acid (VPA) is an anticonvulsant drug that, when administered during pregnancy, causes various birth defects. The mechanisms of action are largely unclear: VPA can reduce neuronal excitability, but it also inhibits the histone deacetylases, affecting gene expression. Here we evaluated whether the effects of valproic acid prenatal exposure on autism spectrum disorder (ASD)-related behavioral phenotypes can be transmitted to the second generation (F2) through the paternal or the maternal lineage. Indeed, we found that F2 males of the VPA pedigree show reduced sociability, which can be rescued by exposing the animals to social enrichment. Moreover, as is the case for F1 males, F2 VPA males show increased c-Fos expression in the piriform cortex. However, F3 males show normal sociability, indicating that VPA's effects on this behavior are not transgenerationally inherited. Female behavior is not affected by VPA exposure, and we found no evidence of maternal transmission of the consequences of this pharmacological treatment. Finally, all animals exposed to VPA and their descendants show reduced body weight, highlighting an intriguing effect of this compound on metabolism. We propose the VPA model of ASD as a valuable mouse model to study the role of epigenetic inheritance and its underlying mechanisms affecting behavior and neuronal function.

Preconception maternal posttraumatic stress and child negative affectivity: Prospectively evaluating the intergenerational impact of trauma

The developmental origins of psychopathology begin before birth and perhaps even prior to conception. Understanding the intergenerational transmission of psychopathological risk is critical to identify sensitive windows for prevention and early intervention. Prior research demonstrates that maternal trauma history, typically assessed retrospectively, has adverse consequences for child socioemotional development. However, very few prospective studies of preconception trauma exist, and the role of preconception symptoms of posttraumatic stress disorder (PTSD) remains unknown. The current study prospectively evaluates whether maternal preconception PTSD symptoms predict early childhood negative affectivity, a key dimension of temperament and predictor of later psychopathology. One hundred and eighteen women were recruited following a birth and prior to conception of the study child and were followed until the study child was 3-5 years old. Higher maternal PTSD symptoms prior to conception predicted greater child negative affectivity, adjusting for concurrent maternal depressive symptoms and sociodemographic covariates. In exploratory analyses, we found that neither maternal prenatal nor postpartum depressive symptoms or perceived stress mediated this association. These findings add to a limited prospective literature, highlighting the importance of assessing the mental health of women prior to conception and providing interventions that can disrupt the intergenerational sequelae of trauma.

Epigenetic control of heredity

Epigenetics is the field of science that deals with the study of changes in gene function that do not involve changes in DNA sequence and are heritable while epigenetics inheritance is the process of transmission of epigenetic modifications to the next generation. It can be transient, intergenerational, or transgenerational. There are various epigenetic modifications involving mechanisms such as DNA methylation, histone modification, and noncoding RNA expression, all of which are inheritable. In this chapter, we summarize the information on epigenetic inheritance, its mechanism, inheritance studies on various organisms, factors affecting epigenetic modifications and their inheritance, and the role of epigenetic inheritance in the heritability of diseases.

The microbiota and immune system non-genetically affect offspring phenotypes transgenerationally

The host-microbiota relationship has evolved to shape mammalian processes, including immunity, metabolism, and development 1-3 . Host phenotypes change in direct response to microbial exposures by the individual. Here we show that the microbiota induces phenotypic change not only in the individual but also in their succeeding generations of progeny. We found that germ-free mice exhibit a robust sebum secretion defect and transcriptional changes in various organs, persisting across multiple generations despite microbial colonization and breeding with conventional mice. Host-microbe interactions could be involved in this process, since T cell-deficient mice, which display defective sebum secretion 4 , also transgenerationally transmit their phenotype to progeny. These phenotypes are inherited by progeny conceived during in vitro fertilization using germ-free sperm and eggs, demonstrating that epigenetic information in the gametes is required for phenotypic transmission. Accordingly, small non-coding RNAs that can regulate embryonic gene expression 5 were strikingly and similarly altered in gametes of germ-free and T cell-deficient mice. Thus, we have uncovered a novel mechanism whereby the microbiota and immune system induce phenotypic changes in successive generations of offspring. This epigenetic form of inheritance could be advantageous for host adaptation to environmental perturbation, where phenotypic diversity can be introduced more rapidly than by genetic mutation.

Epigenetic Effects of Social Stress and Epigenetic Inheritance

Social events that cause stress can cause epigenetic changes on living things. The study of the effects of social events experienced by an individual on epigenetic marks on the genome has created the field of social epigenetics. Social epigenetics examines the effects of psychosocial stress factors such as poverty, war trauma and childhood abuse on epigenetic mechanisms. Epigenetic mechanisms alter chemical markers in the genome structure without changing the DNA sequence. Among these mechanisms, DNA methylation in particular may have different phenotypic effects in response to stressors that may occur in the psychosocial environment. Post-traumatic stress disorder is one of the most significant proofs of the effects of epigenetic expressions altered due to traumatic events on the phenotype. The field of epigenetic inheritance has shown that epigenetic changes triggered by environmental influences can, in some cases, be transmitted through generations. This field provides a better understanding of the basis of many psychological disorders. This review provides an overview of social epigenetics, PTSD, and epigenetic inheritance.

Stress memory and its regulation in plants experiencing recurrent drought conditions

Developing stress-tolerant plants continues to be the goal of breeders due to their realized yields and stability. Plant responses to drought have been studied in many different plant species, but the occurrence of stress memory as well as the potential mechanisms for memory regulation is not yet well described. It has been observed that plants hold on to past events in a way that adjusts their response to new challenges without altering their genetic constitution. This ability could enable training of plants to face future challenges that increase in frequency and intensity. A better understanding of stress memory-associated mechanisms leading to alteration in gene expression and how they link to physiological, biochemical, metabolomic and morphological changes would initiate diverse opportunities to breed stress-tolerant genotypes through molecular breeding or biotechnological approaches. In this perspective, this review discusses different stress memory types and gives an overall view using general examples. Further, focusing on drought stress, we demonstrate coordinated changes in epigenetic and molecular gene expression control mechanisms, the associated transcription memory responses at the genome level and integrated biochemical and physiological responses at cellular level following recurrent drought stress exposures. Indeed, coordinated epigenetic and molecular alterations of expression of specific gene networks link to biochemical and physiological responses that facilitate acclimation and survival of an individual plant during repeated stress.

Intergenerational transmission of psychological trauma: A structural neuroimaging study

Traumatic events have an important effect in human life and may lead to psychopathological disturbances by affecting the personal and social lives of individuals. Recently, various studies have been reported in the literature showing that the traumatic experiences may be associated with intergenerational psychopathologies. However, there is limited data regarding the neuroimaging studies investigating changes in brain structures in children of traumatized mothers. In this study, we aimed to investigate the potential changes in the hippocampus and amygdala volumes in the children of mothers exposed to mass trauma. The traumatic event experienced by the mothers was the two devastating earthquakes they experienced when they were teenagers. Hippocampus and amygdala volumes were evaluated in magnetic resonance imaging of 40 children whose mothers were exposed to earthquakes and 27 children in control group. Bilateral amygdala volumes were significantly smaller in the children of mothers exposed to earthquake compared to the control group. In addition, right amygdala and hippocampus volumes were smaller in children of mothers exposed to earthquakes than left. This is one of the pioneering neuroimaging studies on the intergenerational transmission of trauma. Our study shows that there may be a potential relationship between intergenerational trauma and various brain structures.

Epigenetic mechanisms regulate cue memory underlying discriminative behavior

The burgeoning field of neuroepigenetics has introduced chromatin modification as an important interface between experience and brain function. For example, epigenetic mechanisms like histone acetylation and DNA methylation operate throughout a lifetime to powerfully regulate gene expression in the brain that is required for experiences to be transformed into long-term memories. This review highlights emerging evidence from sensory models of memory that converge on the premise that epigenetic regulation of activity-dependent transcription in the sensory brain facilitates highly precise memory recall. Chromatin modifications may be key for neurophysiological responses to transient sensory cue features experienced in the "here and now" to be recapitulated over the long term. We conclude that the function of epigenetic control of sensory system neuroplasticity is to regulate the amount and type of sensory information retained in long-term memories by regulating neural representations of behaviorally relevant cues that guide behavior. This is of broad importance in the neuroscience field because there are few circumstances in which behavioral acts are devoid of an initiating sensory experience.

Cinnamaldehyde prevents intergenerational effect of paternal depression in mice via regulating GR/miR-190b/BDNF pathway

Paternal stress exposure-induced high corticosterone (CORT) levels may contribute to depression in offspring. Clinical studies disclose the association of depressive symptoms in fathers with their adolescent offspring. However, there is limited information regarding the intervention for intergenerational inheritance of depression. In this study we evaluated the intervention of cinnamaldehyde, a major constituent of Chinese herb cinnamon bark, for intergenerational inheritance of depression in CORT- and CMS-induced mouse models of depression. Depressive-like behaviors were induced in male mice by injection of CORT (20 mg·kg^-1·d^-1, sc) for 6 weeks or by chronic mild stress (CMS) for 6 weeks. We showed that co-administration of cinnamaldehyde (10, 20, or 40 mg·kg^-1·d^-1, ig) for 6 weeks in F0 males prevented the depressive-like phenotypes of F1 male offspring. In addition, co-administration of cinnamaldehyde (20 mg·kg^-1·d^-1, ig) for 4 weeks significantly ameliorated depressive-like behaviors of chronic variable stress (CVS)-stimulated F1 offspring born to CMS mice. Notably, cinnamaldehyde had no reproductive toxicity, while positive drug fluoxetine showed remarkable reproductive toxicity. We revealed that CMS and CORT significantly reduced testis glucocorticoid receptor (GR) expression, and increased testis and sperm miR-190b expression in F0 depressive-like models. Moreover, pre-miR-190b expression was upregulated in testis of F0 males. The amount of GR on miR-190b promoter regions was decreased in testis of CORT-stimulated F0 males. Cinnamaldehyde administration reversed CORT-induced GR reduction in testis, miR-190b upregulation in testis and sperm, pre-miR-190b upregulation in testis, and the amount of GR on miR-190b promoter regions of F0 males. In miR-190b-transfected Neuro 2a (N2a) cells, we demonstrated that miR-190b might directly bind to the 3'-UTR of brain-derived neurotrophic factor (BDNF). In the hippocampus of F1 males of CORT- or CMS-induced depressive-like models, increased miR-190b expression was accompanied by reduced BDNF and GR, which were ameliorated by cinnamaldehyde. In conclusion, cinnamaldehyde is a potential intervening agent for intergenerational inheritance of depression, probably by regulating GR/miR-190b/BDNF pathway.

Generational synaptic functions of GABAA receptor β3 subunit deteriorations in an animal model of social deficit

BACKGROUND

Disruption of normal brain development is implicated in numerous psychiatric disorders with neurodevelopmental origins, including autism spectrum disorder (ASD). Widespread abnormalities in brain structure and functions caused by dysregulations of neurodevelopmental processes has been recently shown to exert adverse effects across generations. An imbalance between excitatory/inhibitory (E/I) transmission is the putative hypothesis of ASD pathogenesis, supporting by the specific implications of inhibitory γ-aminobutyric acid (GABA)ergic system in autistic individuals and animal models of ASD. However, the contribution of GABAergic system in the neuropathophysiology across generations of ASD is still unknown. Here, we uncover profound alterations in the expression and function of GABA_A receptors (GABA_ARs) in the amygdala across generations of the VPA-induced animal model of ASD.

METHODS

The F2 generation was produced by mating an F1 VPA-induced male offspring with naïve females after a single injection of VPA on embryonic day (E12.5) in F0. Autism-like behaviors were assessed by animal behavior tests. Expression and functional properties of GABA_ARs and related proteins were examined by using western blotting and electrophysiological techniques.

RESULTS

Social deficit, repetitive behavior, and emotional comorbidities were demonstrated across two generations of the VPA-induced offspring. Decreased synaptic GABA_AR and gephyrin levels, and inhibitory transmission were found in the amygdala from two generations of the VPA-induced offspring with greater reductions in the F2 generation. Weaker association of gephyrin with GABA_AR was shown in the F2 generation than the F1 generation. Moreover, dysregulated NMDA-induced enhancements of gephyrin and GABA_AR at the synapse in the VPA-induced offspring was worsened in the F2 generation than the F1 generation. Elevated glutamatergic modifications were additionally shown across generations of the VPA-induced offspring without generation difference.

CONCLUSIONS

Taken together, these findings revealed the E/I synaptic abnormalities in the amygdala from two generations of the VPA-induced offspring with GABAergic deteriorations in the F2 generation, suggesting a potential therapeutic role of the GABAergic system to generational pathophysiology of ASD.

Chronic paternal morphine exposure increases sensitivity to morphine-derived pain relief in male progeny

Parental history of opioid exposure is seldom considered when prescribing opioids for pain relief. To explore whether parental opioid exposure may affect sensitivity to morphine in offspring, we developed a "rat pain scale" with high-speed imaging, machine learning, and mathematical modeling in a multigenerational model of paternal morphine self-administration. We find that the most commonly used tool to measure mechanical sensitivity in rodents, the von Frey hair, is not painful in rats during baseline conditions. We also find that male progeny of morphine-treated sires had no baseline changes in mechanical pain sensitivity but were more sensitive to the pain-relieving effects of morphine. Using RNA sequencing across pain-relevant brain regions, we identify gene expression changes within the regulator of G protein signaling family of proteins that may underlie this multigenerational phenotype. Together, this rat pain scale revealed that paternal opioid exposure increases sensitivity to morphine's pain-relieving effects in male offspring.

The prefrontal cortex, pathological anxiety, and anxiety disorders

Anxiety is experienced in response to threats that are distal or uncertain, involving changes in one's subjective state, autonomic responses, and behavior. Defensive and physiologic responses to threats that involve the amygdala and brainstem are conserved across species. While anxiety responses typically serve an adaptive purpose, when excessive, unregulated, and generalized, they can become maladaptive, leading to distress and avoidance of potentially threatening situations. In primates, anxiety can be regulated by the prefrontal cortex (PFC), which has expanded in evolution. This prefrontal expansion is thought to underlie primates' increased capacity to engage high-level regulatory strategies aimed at coping with and modifying the experience of anxiety. The specialized primate lateral, medial, and orbital PFC sectors are connected with association and limbic cortices, the latter of which are connected with the amygdala and brainstem autonomic structures that underlie emotional and physiological arousal. PFC pathways that interface with distinct inhibitory systems within the cortex, the amygdala, or the thalamus can regulate responses by modulating neuronal output. Within the PFC, pathways connecting cortical regions are poised to reduce noise and enhance signals for cognitive operations that regulate anxiety processing and autonomic drive. Specialized PFC pathways to the inhibitory thalamic reticular nucleus suggest a mechanism to allow passage of relevant signals from thalamus to cortex, and in the amygdala to modulate the output to autonomic structures. Disruption of specific nodes within the PFC that interface with inhibitory systems can affect the negative bias, failure to regulate autonomic arousal, and avoidance that characterize anxiety disorders.

Transmission of trained immunity and heterologous resistance to infections across generations

Intergenerational inheritance of immune traits linked to epigenetic modifications has been demonstrated in plants and invertebrates. Here we provide evidence for transmission of trained immunity across generations to murine progeny that survived a sublethal systemic infection with Candida albicans or a zymosan challenge. The progeny of trained mice exhibited cellular, developmental, transcriptional and epigenetic changes associated with the bone marrow-resident myeloid effector and progenitor cell compartment. Moreover, the progeny of trained mice showed enhanced responsiveness to endotoxin challenge, alongside improved protection against systemic heterologous Escherichia coli and Listeria monocytogenes infections. Sperm DNA of parental male mice intravenously infected with the fungus C. albicans showed DNA methylation differences linked to immune gene loci. These results provide evidence for inheritance of trained immunity in mammals, enhancing protection against infections.

The roots of paternal depression: Experienced and nonexperienced trauma or Folie a Deux?

The transition to fatherhood may be challenged with anxiety and trepidation. A high prevalence has been found for paternal depression and it is reactive to maternal depression. This review aims to address potential sources of paternal depression, which may have adverse consequences on child development. We describe through three hypotheses how fathers may be at risk of depression during the transition to fatherhood: (1) psychological (interacting with ecological systems); (2) brain functional∖structural changes; and (3) (epi)genomic. We propose that paternal stressful experiences during the transition to fatherhood may be the source for paternal depression through direct stressful paternal experiences or via (potential, currently debated) nonexperienced (by the father) epigenomic transgenerational transmission. On the other hand, we suggest that resilient fathers may undergo a transient dysphoric period affected by identifying with the newborn's vulnerability as well as with the mother's postpartum vulnerability resulting in "paternity blues." In accordance with recent views on paternal "heightened sensitivity" toward the infant, we propose that the identification of both parents with the vulnerability of the newborn creates a sensitive period of Folie a Deux (shared madness) which may be a healthy transient, albeit a quasi-pathological period, recruited by the orienting response of the newborn for survival.

Alternative models for transgenerational epigenetic inheritance: Molecular psychiatry beyond mice and man

Mental illness remains the greatest chronic health burden globally with few in-roads having been made despite significant advances in genomic knowledge in recent decades. The field of psychiatry is constantly challenged to bring new approaches and tools to address and treat the needs of vulnerable individuals and subpopulations, and that has to be supported by a continuous growth in knowledge. The majority of neuropsychiatric symptoms reflect complex gene-environment interactions, with epigenetics bridging the gap between genetic susceptibility and environmental stressors that trigger disease onset and drive the advancement of symptoms. It has more recently been demonstrated in preclinical models that epigenetics underpins the transgenerational inheritance of stress-related behavioural phenotypes in both paternal and maternal lineages, providing further supporting evidence for heritability in humans. However, unbiased prospective studies of this nature are practically impossible to conduct in humans so preclinical models remain our best option for researching the molecular pathophysiologies underlying many neuropsychiatric conditions. While rodents will remain the dominant model system for preclinical studies (especially for addressing complex behavioural phenotypes), there is scope to expand current research of the molecular and epigenetic pathologies by using invertebrate models. Here, we will discuss the utility and advantages of two alternative model organisms–Caenorhabditis elegans and Drosophila melanogaster–and summarise the compelling insights of the epigenetic regulation of transgenerational inheritance that are potentially relevant to human psychiatry.

Early life adoption shows rearing environment supersedes transgenerational effects of paternal stress on aggressive temperament in the offspring

Prenatal experience and transgenerational influences are increasingly recognized as critical for defining the socio-emotional system, through the development of social competences and of their underlying neural circuitries. Here, we used an established rat model of social stress resulting from male partner aggression induced by peripubertal (P28-42) exposure to unpredictable fearful experiences. Using this model, we aimed to first, characterize adult emotionality in terms of the breadth of the socio-emotional symptoms and second, to determine the relative impact of prenatal vs postnatal influences. For this purpose, male offspring of pairs comprising a control or a peripubertally stressed male were cross-fostered at birth and tested at adulthood on a series of socio-emotional tests. In the offspring of peripubertally stressed males, the expected antisocial phenotype was observed, as manifested by increased aggression towards a female partner and a threatening intruder, accompanied by lower sociability. This negative outcome was yet accompanied by better social memory as well as enhanced active coping, based on more swimming and longer latency to immobility in the forced swim test, and less immobility in the shock probe test. Furthermore, the cross-fostering manipulation revealed that these adult behaviors were largely influenced by the post- but not the prenatal environment, an observation contrasting with both pre- and postnatal effects on attacks during juvenile play behavior. Adult aggression, other active coping behaviors, and social memory were determined by the predominance at this developmental stage of postnatal over prenatal influences. Together, our data highlight the relative persistence of early life influences.

Sequencing the serotonergic neuron translatome reveals a new role for Fkbp5 in stress

Serotonin is a key mediator of stress, anxiety, and depression, and novel therapeutic targets within serotonin neurons are needed to combat these disorders. To determine how stress alters the translational profile of serotonin neurons, we sequenced ribosome-associated RNA from these neurons after repeated stress in male and female mice. We identified numerous sex- and stress-regulated genes. In particular, Fkbp5 mRNA, which codes for the glucocorticoid receptor co-chaperone protein FKBP51, was consistently upregulated in male and female mice following stress. Pretreatment with a selective FKBP51 inhibitor into the dorsal raphe prior to repeated forced swim stress decreased resulting stress-induced anhedonia. Our results support previous findings linking FKBP51 to stress-related disorders and provide the first evidence suggesting that FKBP51 function may be an important regulatory node integrating circulating stress hormones and serotonergic regulation of stress responses.

Paternal adverse childhood experiences: Associations with infant DNA methylation

Adverse childhood experiences (ACEs), or cumulative childhood stress exposures, such as abuse, neglect, and household dysfunction, predict later health problems in both the exposed individuals and their offspring. One potential explanation suggests exposure to early adversity predicts epigenetic modification, especially DNA methylation (DNAm), linked to later health. Stress experienced preconception by mothers may associate with DNAm in the next generation. We hypothesized that fathers' exposure to ACEs also associates with their offspring DNAm, which, to our knowledge, has not been previously explored. An epigenome-wide association study (EWAS) of blood DNAm (n = 45) from 3-month-old infants was regressed onto fathers' retrospective ACEs at multiple Cytosine-phosphate-Guanosine (CpG) sites to discover associations. This accounted for infants' sex, age, ethnicity, cell type proportion, and genetic variability. Higher ACE scores associated with methylation values at eight CpGs. Post-hoc analysis found no contribution of paternal education, income, marital status, and parental postpartum depression, but did with paternal smoking and BMI along with infant sleep latency. These same CpGs also contributed to the association between paternal ACEs and offspring attention problems at 3 years. Collectively, these findings suggested there were biological associations with paternal early life adversity and offspring DNAm in infancy, potentially affecting offspring later childhood outcomes.

Hidden Role of Gut Microbiome Dysbiosis in Schizophrenia: Antipsychotics or Psychobiotics as Therapeutics?

Schizophrenia is a chronic, heterogeneous neurodevelopmental disorder that has complex symptoms and uncertain etiology. Mounting evidence indicates the involvement of genetics and epigenetic disturbances, alteration in gut microbiome, immune system abnormalities, and environmental influence in the disease, but a single root cause and mechanism involved has yet to be conclusively determined. Consequently, the identification of diagnostic markers and the development of psychotic drugs for the treatment of schizophrenia faces a high failure rate. This article surveys the etiology of schizophrenia with a particular focus on gut microbiota regulation and the microbial signaling system that correlates with the brain through the vagus nerve, enteric nervous system, immune system, and production of postbiotics. Gut microbially produced molecules may lay the groundwork for further investigations into the role of gut microbiota dysbiosis and the pathophysiology of schizophrenia. Current treatment of schizophrenia is limited to psychotherapy and antipsychotic drugs that have significant side effects. Therefore, alternative therapeutic options merit exploration. The use of psychobiotics alone or in combination with antipsychotics may promote the development of novel therapeutic strategies. In view of the individual gut microbiome structure and personalized response to antipsychotic drugs, a tailored and targeted manipulation of gut microbial diversity naturally by novel prebiotics (non-digestible fiber) may be a successful alternative therapeutic for the treatment of schizophrenia patients.

Hidden Role of Gut Microbiome Dysbiosis in Schizophrenia: Antipsychotics or Psychobiotics as Therapeutics?

Schizophrenia is a chronic, heterogeneous neurodevelopmental disorder that has complex symptoms and uncertain etiology. Mounting evidence indicates the involvement of genetics and epigenetic disturbances, alteration in gut microbiome, immune system abnormalities, and environmental influence in the disease, but a single root cause and mechanism involved has yet to be conclusively determined. Consequently, the identification of diagnostic markers and the development of psychotic drugs for the treatment of schizophrenia faces a high failure rate. This article surveys the etiology of schizophrenia with a particular focus on gut microbiota regulation and the microbial signaling system that correlates with the brain through the vagus nerve, enteric nervous system, immune system, and production of postbiotics. Gut microbially produced molecules may lay the groundwork for further investigations into the role of gut microbiota dysbiosis and the pathophysiology of schizophrenia. Current treatment of schizophrenia is limited to psychotherapy and antipsychotic drugs that have significant side effects. Therefore, alternative therapeutic options merit exploration. The use of psychobiotics alone or in combination with antipsychotics may promote the development of novel therapeutic strategies. In view of the individual gut microbiome structure and personalized response to antipsychotic drugs, a tailored and targeted manipulation of gut microbial diversity naturally by novel prebiotics (non-digestible fiber) may be a successful alternative therapeutic for the treatment of schizophrenia patients.

Unilateral brain injury to pregnant rats induces asymmetric neurological deficits in the offspring

Effects of environmental factors may be transmitted to the following generation, and cause neuropsychiatric disorders including depression, anxiety, and posttraumatic stress disorder in the offspring. Enhanced synaptic plasticity induced by environmental enrichment may be also transmitted. We here test the hypothesis that the effects of brain injury in pregnant animals may produce neurological deficits in the offspring. Unilateral brain injury (UBI) by ablation of the hindlimb sensorimotor cortex in pregnant rats resulted in the development of hindlimb postural asymmetry (HL-PA), and impairment of balance and coordination in beam walking test in the offspring. The offspring of rats with the left UBI exhibited HL-PA before and after spinal cord transection with the contralesional (i.e., right) hindlimb flexion. The right UBI caused the offspring to develop HL-PA that however was cryptic and not-lateralized; it was evident only after spinalization, and was characterized by similar occurrence of the ipsi- and contralesional hindlimb flexion. The HL-PA persisted after spinalization suggesting that the asymmetry was encoded in lumbar spinal neurocircuits that control hindlimb muscles. Balance and coordination were affected by the right UBI but not the left UBI. Thus, the effects of a unilateral brain lesion in pregnant animals may be intergenerationally transmitted, and this process may depend on the side of brain injury. The results suggest the existence of left-right side-specific mechanisms that mediate transmission of the lateralized effects of brain trauma from mother to fetus.

The Impact of Perinatal Life Stress on Infant Temperament and Child Development: A 2-Year Follow-Up Cohort Study

BACKGROUND

Accumulating evidence suggests a persistent impact of perinatal exposure to maternal stress on the infant. In utero, the fetus is particularly vulnerable to maternal stress and mental health complications with various long-term consequences. This study examines the prospective relationship of subclinical maternal perinatal life stress based on individual responses to stressful life events and infant temperament and child development.

METHODS

Data were derived from the Akershus Birth Cohort, a longitudinal cohort study including 3,752 women scheduled to give birth at Akershus University Hospital, Norway. Psychometric measures pertained to perinatal life stress, maternal perinatal depression (Edinburgh Postnatal Depression Scale), difficult infant temperament at 8 weeks (Infant Characteristics Questionnaire), and child development 2 years after birth (Ages & Stages Questionnaire).

RESULTS

Perinatal life stress predicted difficult infant temperament at 8 weeks and challenges in social-emotional development at 2 years above and beyond demographics, pregnancy, and childbirth-related and postpartum factors.

CONCLUSION

Life events perceived as severely distressing in the peripartum period pose a burden on mothers and may have potentially detrimental long-term effects on neurobiological and social-emotional child development. Our findings highlight the need for person-centered perinatal care and support of mothers facing difficult life events. Clinical awareness of in utero development and its relationship to maternal psychological health is warranted to intervene effectively. Future research should consider the timing of in utero exposure and neurobiological and environmental mechanisms pertaining to the relationship between maternal perinatal life stress and child development.

Prevalence of Intimate Partner Violence Among Intimate Partners During the Perinatal Period: A Narrative Literature Review

Intimate partner violence (IPV) affects individuals and families from all backgrounds, regardless of their ethnicity, socio-economic status, sexual orientation, or religion. Pregnancy and childbirth could be a time of vulnerability to violence because of changes in physical, emotional, social, and economic demands and needs. Prevalence of IPV against women during the perinatal period is increasingly researched and documented. However, evidence on IPV prevalence among intimate partners as well as on the course of IPV over the perinatal period is scarce. The purpose of this review was to provide a narrative synthesis of the existing literature regarding the prevalence estimates of IPV among intimate partners over the perinatal period. Through this review, we also gained better insight into associated factors, as well as the various forms of IPV. Of the 766 studies assessing prevalence estimates identified, 86 were included, where 80 studies focused on unidirectional IPV (i.e., perpetrated by men against women) and six studies investigated bidirectional IPV (i.e., IPV perpetrated by both partners). Most of the included studies reported lower overall prevalence rates for unidirectional IPV postpartum (range: 2-58%) compared to pregnancy (range: 1.5-66.9%). Psychological violence was found to be the most prevalent form of violence during the entire perinatal period. Studies on bidirectional IPV mostly reported women's perpetration to be almost as high as that of their partner or even higher, yet their findings need to be interpreted with caution. In addition, our results also highlighted the associated factors of IPV among partners, in which they were assimilated into a multi-level ecological model and were analyzed through an intersectional framework. Based on our findings, IPV is found to be highly prevalent during the entire perinatal period and in populations suffering from social inequalities. Further research exploring not only the occurrence, but also the motivations and the context of the bidirectionality of IPV during the perinatal period may facilitate better understanding of the detrimental consequences on partners and their families, as well as the development of effective intervention strategies. Public health prevention approaches intervening at optimal times during the perinatal period are also needed.

Intergenerational influence of paternal physical activity on the offspring's brain: A systematic review and meta-analysis

BACKGROUND

It is well established that parents can influence their offspring's neurodevelopment. It is shown that paternal environment and lifestyle is beneficial for the progeny's fitness and might affect their metabolic mechanisms; however, the effects of paternal exercise on brain in the offspring have not been explored in detail.

OBJECTIVE

This study aims to review the impact of paternal physical exercise on memory and learning, neuroplasticity, as well as DNA methylation levels in the offspring's hippocampus.

STUDY DESIGN

In this systematic review and meta-analysis, electronic literature search was conducted in databases including PubMed, Scopus, and Web of Science. Eligible studies were those with an experimental design, including an exercise intervention arm, with assessment of any type of memory function, learning ability, or any type of brain plasticity as the outcome measures. Standardized mean difference (SMD) and 95% confidence intervals (CI) were computed as effect size.

RESULTS

The systematic review revealed the important role of environmental enrichment in the behavioral development of next generation. Also, offspring of exercised fathers displayed higher levels of memory ability, and lower level of brain-derived neurotrophic factor. A significant effect of paternal exercise on the hippocampal volume was also reported in the few available studies.

CONCLUSION

These results suggest an intergenerational effect of paternal physical activity on cognitive benefit, which may be associated with hippocampal epigenetic programming in offspring. However, the biological mechanisms of this modulation remain to be determined.

Early-life and parental predation risk shape fear acquisition in adult minnows

Exposure to predation risk can induce a fearful baseline state, as well as fear reactions toward novel situations (i.e., neophobia). Some research indicates that risk exposure during sensitive periods makes adults more prone to acquiring long-term fearful phenotypes. However, chronic risk can also lead to ignoring threats in order to maintain other activities. We sought to assess how a relatively long period of low risk, experienced either early in life or by the previous generation, influences fear behaviour acquired from a short period of high risk as adults. We used fathead minnows as study subjects and simulated predation risk with repeated exposures to conspecific chemical alarm cues. The period of high risk experienced by adults induced typical fear behaviour (baseline freezing and neophobia), whereas the early-life low-risk period 1 year prior caused only a reduction in baseline foraging. We found no evidence that the early-life risk significantly altered the fear acquired from the adult-risk period. However, in a second experiment, a low-risk period during the parental generation interacted with a high-risk period experienced by the adult offspring. The combination of both risk periods heightened baseline freezing despite parental risk having little effect independently. Hence, our study provides evidence that parental risk exposure can lead to an additive intergenerational effect on fear acquisition in minnows.

Repeated sampling facilitates within- and between-subject modeling of the human sperm transcriptome to identify dynamic and stress-responsive sncRNAs

Epidemiological studies from the last century have drawn strong associations between paternal life experiences and offspring health and disease outcomes. Recent studies have demonstrated sperm small non-coding RNA (sncRNA) populations vary in response to diverse paternal insults. However, for studies in retrospective or prospective human cohorts to identify changes in paternal germ cell epigenetics in association with offspring disease risk, a framework must first be built with insight into the expected biological variation inherent in human populations. In other words, how will we know what to look for if we don't first know what is stable and what is dynamic, and what is consistent within and between men over time? From sperm samples from a 'normative' cohort of healthy human subjects collected repeatedly from each subject over 6 months, 17 healthy male participants met inclusion criteria and completed donations and psychological evaluations of perceived stress monthly. sncRNAs (including miRNA, piRNA, and tRNA) isolated from mature sperm from these samples were subjected to Illumina small RNA sequencing, aligned to subtype-specific reference transcriptomes, and quantified. The repeated measures design allowed us to define both within- and between-subject variation in the expression of 254 miRNA, 194 tRNA, and 937 piRNA in sperm over time. We developed screening criteria to identify a subset of potential environmentally responsive 'dynamic' sperm sncRNA. Implementing complex modeling of the relationships between individual dynamic sncRNA and perceived stress states in these data, we identified 5 miRNA (including let-7f-5p and miR-181a-5p) and 4 tRNA that are responsive to the dynamics of prior stress experience and fit our established mouse model. In the current study, we aligned repeated sampling of human sperm sncRNA expression data with concurrent measures of perceived stress as a novel framework that can now be applied across a range of studies focused on diverse environmental factors able to influence germ cell programming and potentially impact offspring development.

Review of psychological stress on oocyte and early embryonic development in female mice

Psychological stress can cause adverse health effects in animals and humans. Accumulating evidence suggests that psychological stress in female mice is associated with ovarian developmental abnormalities accompanied by follicle and oocyte defects. Oocyte and early embryonic development are impaired in mice facing psychological stress, likely resulting from hormone signalling disorders, reactive oxygen species (ROS) accumulation and alterations in epigenetic modifications, which are primarily mediated by the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-ovarian (HPO) axes. The present evidence suggests that psychological stress is increasingly becoming the most common causative factor for female subfertility. Here, we review recent progress on the impact of psychological stress on female reproduction, particularly for oocyte and early embryonic development in female mice. This review highlights the connection between psychological stress and reproductive health and provides novel insight on human subfertility.

Characterization of the intergenerational impact of in utero and postnatal oxycodone exposure

Prescription opioid abuse during and after pregnancy is a rising public health concern. While earlier studies have documented that offspring exposed to opioids in utero have impaired neurodevelopment, a significant knowledge gap remains in comparing the overall development between offspring exposed in utero and postnatally. Adding a layer of complexity is the role of heredity in the overall development of these exposed offspring. To fill in these important knowledge gaps, the current study uses a preclinical rat model mimicking oxycodone (oxy) exposure in utero (IUO) and postnatally (PNO) to investigate comparative and intergenerational effects in the two different treatment groups. While significant phenotypic attributes were observed with the two treatments and across the two generations, RNA sequencing revealed alterations in the expression of key synaptic genes in the two exposed groups in both generations. RNA sequencing and post validation of genes using RT-PCR highlighted the differential expression of several neuropeptides associated with the hypocretin system, a system recently implicated in addiction. Further, behavior studies revealed anxiety-like behaviors and social deficits that persisted even in the subsequent generations in the two treatment groups. To summarize, our study for the first time reveals a new line of investigation on the potential risks associated with oxy use during and after pregnancy, specifically the disruption of neurodevelopment and intergenerational impact on behavior.

Psychosocial Stress and Adversity: Effects from the Perinatal Period to Adulthood

Early exposure to stress and adversity can have both immediate and lasting effects on physical and psychological health. Critical periods have been identified in infancy, during which the presence or absence of experiences can alter developmental trajectories. There are multiple explanations for how exposure to psychosocial stress, before conception or early in life, has an impact on later increased risk for developmental delays, mental health, and chronic metabolic diseases. Through both epidemiologic and animal models, the mechanisms by which experiences are transmitted across generations are being identified. Because psychosocial stress has multiple components that can act as stress mediators, a comprehensive understanding of the complex interactions between multiple adverse or beneficial experiences and their ultimate effects on health is essential to best identify interventions that will improve health and outcomes. This review outlines what is known about the biology, transfer, and effects of psychosocial stress and early life adversity from the perinatal period to adulthood. This information can be used to identify potential areas in which clinicians in neonatal medicine could intervene to improve outcomes.

Intergenerational Effects of Maternal Holocaust Exposure on FKBP5 Methylation

OBJECTIVE

There is growing evidence that exposure to trauma prior to conception can affect offspring. The authors have reported that adult offspring of Holocaust survivors showed lower methylation of FK506 binding protein 5 (FKBP5) intron 7, site 6 compared with Jewish comparison volunteers. The present study sought to replicate this finding in a larger sample and to examine parental and offspring correlates of observed effects.

METHODS

Cytosine methylation was measured in blood using pyrosequencing. The independent replication sample consisted of 125 Holocaust offspring and 31 control subjects. Additional analyses, performed in a larger sample of 147 offspring and 40 control subjects that included the 31 previously studied participants, examined associations of parental trauma-related variables (i.e., sex of the exposed parent, parental posttraumatic stress disorder, age at Holocaust exposure) and offspring characteristics (i.e., childhood trauma exposure, lifetime psychiatric diagnoses, psychotropic medication use, FKBP5 rs1360780 genotype, FKBP5 gene expression, and neuroendocrine measures) with offspring FKBP5 methylation.

RESULTS

FKBP5 site 6 methylation was significantly lower in Holocaust offspring than in control subjects, an effect associated with maternal Holocaust exposure in childhood and with lower offspring self-reported anxiety symptoms. FKBP5 gene expression was elevated in Holocaust offspring. FKBP5 methylation was associated with indices of glucocorticoid sensitivity but not with basal FKBP5 gene expression.

CONCLUSIONS

This study replicates and extends the previously observed decrement in FKBP5 intron 7, site 6 methylation in Holocaust offspring. The predominance of this effect in offspring of mothers exposed during childhood implicates maternal developmental programming as a putative mechanism.

Maternal mental health and infant emotional reactivity: a 20-year two-cohort study of preconception and perinatal exposures

BACKGROUND

Maternal mental health during pregnancy and postpartum predicts later emotional and behavioural problems in children. Even though most perinatal mental health problems begin before pregnancy, the consequences of preconception maternal mental health for children's early emotional development have not been prospectively studied.

METHODS

We used data from two prospective Australian intergenerational cohorts, with 756 women assessed repeatedly for mental health problems before pregnancy between age 13 and 29 years, and during pregnancy and at 1 year postpartum for 1231 subsequent pregnancies. Offspring infant emotional reactivity, an early indicator of differential sensitivity denoting increased risk of emotional problems under adversity, was assessed at 1 year postpartum.

RESULTS

Thirty-seven percent of infants born to mothers with persistent preconception mental health problems were categorised as high in emotional reactivity, compared to 23% born to mothers without preconception history (adjusted OR 2.1, 95% CI 1.4-3.1). Ante- and postnatal maternal depressive symptoms were similarly associated with infant emotional reactivity, but these perinatal associations reduced somewhat after adjustment for prior exposure. Causal mediation analysis further showed that 88% of the preconception risk was a direct effect, not mediated by perinatal exposure.

CONCLUSIONS

Maternal preconception mental health problems predict infant emotional reactivity, independently of maternal perinatal mental health; while associations between perinatal depressive symptoms and infant reactivity are partially explained by prior exposure. Findings suggest that processes shaping early vulnerability for later mental disorders arise well before conception. There is an emerging case for expanding developmental theories and trialling preventive interventions in the years before pregnancy.

MeCP2 mediates transgenerational transmission of chronic pain

Pain symptoms can be transmitted across generations, but the mechanisms underlying these outcomes remain poorly understood. Here, we identified an essential role for primary somatosensory cortical (S1) glutamate neuronal DNA methyl-CpG binding protein 2 (MeCP2) in the transgenerational transmission of pain. In a female mouse chronic pain model, the offspring displayed significant pain sensitization. In these mice, MeCP2 expression was increased in S1 glutamate (Glu^S1) neurons, correlating with increased neuronal activity. Downregulation of Glu^S1 neuronal MeCP2 in maternal mice with pain abolished offspring pain sensitization, whereas overexpression of MeCP2 in naïve maternal mice induced pain sensitization in offspring. Notably, single-cell sequencing and chromatin immunoprecipitation analysis showed that the expression of a wide range of genes was changed in offspring and maternal Glu^S1 neurons, some of which were regulated by MeCP2. These results collectively demonstrate the putative importance of MeCP2 as a key regulator in pain transgenerational transmission through actions on Glu^S1 neuronal maladaptation.

The applied implications of epigenetics in anxiety, affective and stress-related disorders - A review and synthesis on psychosocial stress, psychotherapy and prevention

Mental disorders are highly complex and multifactorial in origin, comprising an elaborate interplay of genetic and environmental factors. Epigenetic mechanisms such as DNA modifications (e.g. CpG methylation), histone modifications (e.g. acetylation) and microRNAs function as a translator between genes and the environment. Indeed, environmental influences such as exposure to stress shape epigenetic patterns, and lifetime experiences continue to alter the function of the genome throughout the lifespan. Here, we summarize the recently burgeoning body of research regarding the involvement of aberrant epigenetic signatures in mediating an increased vulnerability to a wide range of mental disorders. We review the current knowledge of epigenetic changes to constitute useful markers predicting the clinical response to psychotherapeutic interventions, and of psychotherapy to alter - and potentially reverse - epigenetic risk patterns. Given first evidence pointing to a transgenerational transmission of epigenetic information, epigenetic alterations arising from successful psychotherapy might be transferred to future generations and thus contribute to the prevention of mental disorders. Findings are integrated into a multi-level framework highlighting challenges pertaining to the mechanisms of action and clinical implications of epigenetic research. Promising future directions regarding the prediction, prevention, and personalized treatment of mental disorders in line with a 'precision medicine' approach are discussed.

A review of epigenetic contributions to post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a syndrome which serves as a classic example of psychiatric disorders that result from the intersection of nature and nurture, or gene and environment. By definition, PTSD requires the experience of a traumatic exposure, and yet data suggest that the risk for PTSD in the aftermath of trauma also has a heritable (genetic) component. Thus, PTSD appears to require both a biological (genetic) predisposition that differentially alters how the individual responds to or recovers from trauma exposure. Epigenetics is defined as the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself, and more recently it has come to refer to direct alteration of DNA regulation, but without altering the primary sequence of DNA, or the genetic code. With regards to PTSD, epigenetics provides one way for environmental exposure to be "written" upon the genome, as a direct result of gene and environment (trauma) interactions. This review provides an overview of the main currently understood types of epigenetic regulation, including DNA methylation, histone regulation of chromatin, and noncoding RNA regulation of gene expression. Furthermore, we examine recent literature related to how these methods of epigenetic regulation may be involved in differential risk and resilience for PTSD in the aftermath of trauma.
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The effect of maternal high-fat/high-sugar diet on offspring oocytes and early embryo development

Observational human data and several lines of animal experimental data indicate that maternal obesity impairs offspring health. Here, we comprehensively tested the model that maternal obesity causes defects in the next three generations of oocytes and embryos. We exposed female F0 mice to a high-fat/high-sugar (HF/HS) diet for 6 weeks before conception until weaning. Sires, F1 offspring and all subsequent generations were fed control chow diet. Oocytes from F1, F2 and F3 offspring of obese mothers had lower mitochondrial mass and less ATP and citrate than oocytes from offspring of control mothers. F0 blastocysts from HF/HS-exposed mice, but not F1 and F2 blastocysts, had lower mitochondrial mass and membrane potential, less citrate and ATP and smaller total cell number than F0 blastocysts from control mothers. Finally, supplementation of IVF media with the anti-oxidant mito-esculetin partially prevented the oocyte mitochondrial effects caused by maternal HF/HS diet. Our results support the idea that maternal obesity impairs offspring oocyte quality and suggest that antioxidant supplementation should be tested as a means to improve IVF outcomes for obese women.