Environmental exposures co-occurring during early life have a profound influence on neurodevelopment. Our previous work in rats suggests that postnatal maternal care modulates the effects of prenatal exposure to bisphenols, an estrogenic endocrine disrupting chemical, on offspring neurodevelopment. Elevated maternal licking/grooming and prenatal bisphenol exposure have opposing effects on estrogen receptor expression in the medial preoptic area (MPOA), which could impact expression of estrogen-responsive genes. We hypothesized that maternal licking/grooming would mitigate the effects of prenatal bisphenol exposure on estrogen receptor signaling in the developing MPOA. In addition, we hypothesized that there would be interactive effects of prenatal bisphenol exposure and maternal licking/grooming on DNA methylation nearby estrogen responsive elements. Female pups prenatally exposed to bisphenols had elevated estrogen-related receptor gamma (Esrrg) expression in the MPOA, which was reduced for pups that received higher levels of maternal licking/grooming. These mitigating impacts were also evident in co-expression gene profiles that were enriched for estrogen-responsive genes and genes that interact with estrogen receptors. DNA methylation analyses indicated that maternal licking/grooming levels influenced the number of differentially methylated regions for prenatal bisphenol-exposed pups. These differentially methylated regions were enriched for binding sites for transcription factors that interact with estrogen receptors. Finally, supplemental “licking-like” tactile stimulation normalized the DNA methylome in prenatal bisphenol-exposed female pups, with an increase and normalization of ESRRG binding to ESRRG-responsive genes. These results identify a novel biological mechanism in which maternal licking/grooming can mitigate the potential adverse neurodevelopmental impacts of prenatal bisphenol exposure and provides a proof-of-concept for postnatal tactile stimulation as a potential intervention strategy to improve neurodevelopmental outcomes.

This cohort study whether childhood history of maltreatment is associated with late-midlife biological age.

Once dismissed as “junk”, transposable elements (TEs) have recently gained recognition for their regulatory roles, notably in the brain and during development. The brain is hormone-responsive and the hippocampus in particular is sensitive to circulating gonadal hormones. While transcriptionally active, TE function remains poorly understood, especially in the brain. We and other researchers have shown that one particular TE RNA, B2 SINE ncRNA, is a regulator in the rodent hippocampus, especially after a psychologically stressful event like acute restraint stress. However, it is unknown if B2 SINE ncRNA is necessary for the proper development of hippocampal neurons, and, furthermore, if there are sex differences in this development. This work investigates the differences in the expression of B2 SINE RNA across sexes and its role in the development of primary hippocampal neurons. We utilized pooled locked nucleic acid (LNA) GapmeRs to knock down the expression of B2 SINE RNA, and we treated primary hippocampal neurons with dihydrotestosterone (DHT) to test if there is a difference in dendritic complexity. We used Sholl analysis to quantify branching, number of tips, and Sholl mean. We found a sex difference in both B2 SINE, higher in males compared to females, and ß-actin, lower in males compared to females. Additionally, knocking down B2 SINE RNA results in a reduction in dendritic complexity in male but not in female neurons. Taken together, this work suggests that B2 SINE RNA is expressed differentially and that it plays an important role in the proper development of hippocampal neurons in a sex-dependent manner. Our findings support the identification of a sex-specific biomarker that may enable individualized treatment of conditions influenced by sex. This is the first evidence of the role B2 SINE RNA may play in the regulation of the development of neuronal dendritic structure and the first to show differential regulation by sex.

Early life adversity has lasting effects on neuroendocrine function and increases risk for psychopathology and metabolic disease. Stress and metabolism are closely intertwined, with critical periods for early life stress overlapping those for metabolic programming. Early life adversity models in rodents have the potential to affect development through multiple pathways, including nutrition, parental behavior, and direct physical stress. In the current study, we investigate how a limited bedding and nesting material (LBN) postnatal environment affects maternal behavior, milk composition, and acute metabolic outcomes in rat offspring. We examined the impact of LBN exposure during two postnatal windows (Early: P0-6 and/or Late: P6-13) and effects of key elements of early experiences (maternal behavior and nutrition) on acute metabolic outcomes, with assessment of sex-specific effects in pups. LBN shifted maternal behavioral phenotype, increased dam milk corticosterone and triglyceride concentration, affected serum metabolic and pituitary hormones in pups, and increased pup estimated daily energy expenditure. Differential gene expression analyses of the liver and arcuate nucleus of the hypothalamus showed timing and sex-specific effects of LBN. LBN predicted expression of genes related to amino acid biosynthesis, protein assembly, and developmental transitions. These effects were associated with individual milk components, pup sex, and pup weight. Collectively, these findings demonstrate that early life adversity alters acute metabolic outcomes through multiple, interacting pathways that may contribute to increased vulnerability to endocrine and metabolic dysfunction later in life.

Prenatal exposure to endocrine disrupting chemicals, such as bisphenols, can alter neurodevelopmental trajectories and have a lasting neurobehavioral impact through epigenetic pathways. However, outcomes associated with prenatal bisphenol exposure may also be shaped by the postnatal environment and collectively these environmental effects may be sex-specific. Thus, an integrative research design that includes multiple early life exposures and considers sex differences may be essential for predicting outcomes. In the current study, we use a multivariate approach to examine the contributions of prenatal bisphenol exposure, postnatal maternal care, and offspring sex to variation in DNA methylation of well-studied candidate genes (NR3C1, BDNF, OXTR) in the ventral hippocampus and amygdala of adult Long-Evans rats. Main effects of postnatal maternal care and interactions with prenatal bisphenol exposure were consistently found for DNA methylation within the NR3C1 gene (ventral hippocampus) and within the BDNF and OXTR genes (amygdala). Sex-specific effects were also found across all analyses. Overall, our findings suggest that both early-life factors (prenatal and postnatal) and offspring sex contribute to variation in DNA methylation in genes and brain regions relevant for the expression of anxiety-like behavior. These results highlight the need to consider the brain region-specific effects of multiple exposures in males and females to understand the lasting effects of early environments.

Environmental exposures co-occurring during early life have a profound influence on neurodevelopment. Our previous work in rats suggests that postnatal maternal care modulates the effects of prenatal exposure to bisphenols, an estrogenic endocrine disrupting chemical, on offspring neurodevelopment. Elevated postnatal maternal licking/grooming and prenatal bisphenol exposure have known opposing effects on estrogen receptor alpha (Esr1) expression in the medial preoptic area (MPOA) of the hypothalamus, which could impact expression of estrogen-responsive genes. Opposing effects on DNA methylation of Esr1 have also been observed as a consequence of these exposures, with potentially broad transcriptional effects. Based on this previous work, we hypothesized that postnatal maternal licking/grooming would mitigate the effects of prenatal bisphenol exposure on Esr1 expression and estrogen-responsive genes in the developing MPOA. In addition, we hypothesized that there would be interactive effects of prenatal bisphenol exposure and postnatal maternal licking/grooming on DNA methylation, particularly nearby estrogen responsive elements. We administered either a bisphenol mixture (BPA, BPF, BPS), BPA only, or a corn oil control to pregnant rat dams. Postnatal maternal care was measured using home-cage videos. Brains from male and female pups were collected at postnatal day 10 and the transcriptome and DNA methylome were assessed in the MPOA. Our results indicated a significant interaction between prenatal bisphenol exposure and maternal postnatal licking/grooming on estrogen-related receptor gamma (Esrrg) expression, exclusively in female pups. These interactions were also evident in co-expression gene profiles in female pups; the majority of which were enriched for estrogen-responsive genes. Finally, DNA methylation analyses indicated that adding postnatal maternal licking/grooming as a covariate influenced the number of differentially methylated regions for prenatal bisphenol-exposed male and female pups. While these differentially methylated regions were not enriched for estrogen responsive elements, there were binding motifs for transcription factors that are known to interact with estrogen receptors, suggesting some secondary effects on postnatal gene regulation. These results suggest a novel biological mechanism in which postnatal maternal care can mitigate the negative neurodevelopmental impacts of prenatal bisphenol exposure.

Maternal behavior experienced in early life provides essential scaffolding to infant psychobiology with life-long effects on neurobiological and behavioral outcomes. However, infants are not passive recipients of caregiving. Evidence in rodents suggests that pups actively contribute to dam-pup interactions by soliciting maternal care with auditory, tactile, and hormonal cues. The limited bedding and nesting material (LBN) rearing manipulation induces changes in maternal care that have been attributed to maternal stress caused by the low-resource environment. The goal of the current study was to determine whether LBN also alters pup cues for maternal behavior, with implications for the mechanism of LBN-induced effects. Rat dams and pups were randomly assigned to LBN or Control rearing conditions on postnatal day (P) 0-6 and pups were fostered to the same or different condition on P6-13. LBN increased pup-directed maternal behaviors measured through 24 h monitoring using machine learning based automated analysis. LBN altered several pup cues known to affect maternal behavior including reducing pup core body temperature, reducing body weight, and altering pup vocalizations on P6 and P12. P6-13 LBN-exposed pups had elevated serum testosterone, which positively correlated with maternal licking and grooming. LBN reduced pup movement between nest attendance onset and the start of nursing, which was negatively related to dam nursing latency and contributed to longer nursing latency in LBN dams. P0-6 pup exposure to LBN also led to longer nest attendance bouts and shorter licking and grooming bouts on P7 and P9, suggesting lasting effects of LBN on pups. These data demonstrate that LBN changes pup behavioral and hormonal signals consistent with eliciting more maternal care, contributing to augmented pup-directed behaviors. This bidirectional interplay may be a critical mechanism involved in the lasting effects of early life environments.

Mother-infant interactions during the early postnatal period are critical for infant survival and the scaffolding of infant development. Rodent models are used extensively to understand how these early social experiences influence neurobiology across the lifespan. However, methods for measuring postnatal dam-pup interactions typically involve time-consuming manual scoring, vary widely between research groups, and produce low density data that limits downstream analytical applications. To address these methodological issues, we developed the Automated Maternal Behavior during Early life in Rodents (AMBER) pipeline for quantifying home-cage maternal and mother–pup interactions using open-source machine learning tools. DeepLabCut was used to track key points on rat dams (32 points) and individual pups (9 points per pup) in postnatal day 1–10 video recordings. Pose estimation models reached key point test errors of approximately 4.1–10 mm (14.39 pixels) and 3.44–7.87 mm (11.81 pixels) depending on depth of animal in the frame averaged across all key points for dam and pups respectively. Pose estimation data and human-annotated behavior labels from 38 videos were used with Simple Behavioral Analysis (SimBA) to generate behavior classifiers for dam active nursing, passive nursing, nest attendance, licking and grooming, self-directed grooming, eating, and drinking using random forest algorithms. All classifiers had excellent performance on test frames, with F 1 scores above 0.886. Performance on hold-out videos remained high for nest attendance (F 1 = 0.990), active nursing (F 1 = 0.828), and licking and grooming (F 1 = 0.766) but was lower for eating, drinking, and self-directed grooming (F 1 = 0.534–0.554). A set of 242 videos was used with AMBER and produced behavior measures in the expected range from postnatal 1–10 home-cage videos. This pipeline is a major advancement in assessing home-cage dam-pup interactions in a way that reduces experimenter burden while increasing reproducibility, reliability, and detail of data for use in developmental studies without the need for special housing systems or proprietary software.

The Developmental Origins of Health and Disease (DOHaD) hypothesis describes how maternal stress exposures experienced during critical periods of perinatal life are linked to altered developmental trajectories in offspring. Perinatal stress also induces changes in lactogenesis, milk volume, maternal care, and the nutritive and non-nutritive components of milk, affecting short and long-term developmental outcomes in offspring. For instance, selective early life stressors shape the contents of milk, including macro/micronutrients, immune components, microbiota, enzymes, hormones, milk-derived extracellular vesicles, and milk microRNAs. In this review, we highlight the contributions of parental lactation to offspring development by examining changes in the composition of breast milk in response to three well-characterized maternal stressors: nutritive stress, immune stress, and psychological stress. We discuss recent findings in human, animal, and in vitro models, their clinical relevance, study limitations, and potential therapeutic significance to improving human health and infant survival. We also discuss the benefits of enrichment methods and support tools that can be used to improve milk quality and volume as well as related developmental outcomes in offspring. Lastly, we use evidence-based primary literature to convey that even though select maternal stressors may modulate lactation biology (by influencing milk composition) depending on the severity and length of exposure, exclusive and/or prolonged milk feeding may attenuate the negative in utero effects of early life stressors and promote healthy developmental trajectories. Overall, scientific evidence supports lactation to be protective against nutritive and immune stressors, but the benefits of lactation in response to psychological stressors need further investigation.

Bisphenols (BP), including BPA and “BPA-free” structural analogs, are commonly used plasticizers that are present in many plastics and are known endocrine disrupting chemicals. Prenatal exposure to BPA has been associated with negative neurodevelopmental and behavioral outcomes in children and in rodent models. Prenatal BPA exposure has also been shown to impair postnatal maternal care provisioning, which can also affect offspring neurodevelopment and behavior. However, there is limited knowledge regarding the biological effects of prenatal exposure to bisphenols other than BPA and the interplay between prenatal bisphenol exposure and postnatal maternal care on adult behavior. The purpose of the current study was to determine the interactive impact of prenatal bisphenol exposure and postnatal maternal care on neurodevelopment and behavior in rats. Our findings suggest that the effects of prenatal bisphenol exposure on eye-opening, adult attentional set shifting and anxiety-like behavior in the open field are dependent on maternal care in the first five days of life. Interestingly, maternal care might also attenuate the effects of prenatal bisphenol exposure on eye opening and adult attentional set shifting. Finally, transcriptomic profiles in male and female medial prefrontal cortex and amygdala suggest that the interactive effects of prenatal bisphenol exposure and postnatal maternal care converge on estrogen receptor signaling and are involved in biological processes related to gene expression and protein translation and synthesis. Overall, these findings indicate that postnatal maternal care plays a critical role in the expression of the effects of prenatal bisphenol exposure on neurodevelopment and adult behavior. Understanding the underlying biological mechanisms involved might allow us to identify potential avenues to mitigate the adverse effects of prenatal bisphenol exposure and improve health and well-being in human populations.

The early life origins of risk for mood disorders and anxiety are supported by longitudinal studies in humans, particularly those focused on the experience of childhood adversity. Animal models have further supported the association between stress exposure during infancy and neurodevelopmental and physiological processes that shape behavioral indices of depression and anxiety. In rodents, these models have focused on disruption to mother–infant interactions that occur either naturally or through manipulation of the quantity and/or quality of maternal care. Though these models are challenging to implement, they serve as essential tools for establishing or characterizing the neurodevelopmental trajectories that lead to increased risk of psychopathology. In this chapter, we will describe methods that can be used to quantify maternal behavior in rats and mice, with particular emphasis on the use of newly developed video recording and machine learning approaches. We will also describe the premise and protocol for an established methodology to effectively manipulate mother–infant interactions within experimental designs that are exploring neurobiological and behavioral outcomes in offspring. This limited bedding and nesting material (LBN) manipulation is used broadly to study the impact of early life stress in rodents and when combined with high-resolution behavioral quantification approaches can yield novel hypotheses regarding the molecular, cellular, physiological, and behavioral mechanisms that contribute to altered brain function across the life span.

In rodents, gonadal steroids play a critical yet variable role in behaviors such as social interaction and cognitive performance. Gonadal steroids organize sex differences observed in spatial working memory, while the absence of activational effects induced by castration generally impedes spatial learning and memory. Although male sexual behavior is typically inhibited following castration, a significant proportion of gonadectomized B6D2F1 hybrid males retains the complete repertoire of male reproductive behavior. In a prior study, amyloid precursor protein and tau, proteins involved in cognitive behavior, facilitated steroid-independent male sex behavior in B6D2F1 hybrid male mice. We used this strain to investigate the relationship between gonadal steroidindependent male sexual behavior and cognition. After identifying "maters" (animals retaining steroidindependent male sex behavior) and "non-maters," we tested spatial memory in an 8-arm radial arm maze. Although neither group demonstrated a decrease in errors as a function of time, maters committed fewer errors compared to non-maters overall (p < 0.05). Maters also completed the maze more quickly than non-maters (p < 0.05). We measured mRNA expression of APP and MAPT as well as LEPR and D2R to probe potential roles of metabolism and motivation. Uniquely among maters, increased relative expression of D2R and LEPR in the hippocampus was associated with a longer latency to complete the maze during the last 3 or across all trials, respectively. These data demonstrate that maters outperform non-maters in the radial arm maze, warranting further study of potential differences in acquisition of spatial memory tasks or learning strategy between these groups.

Products containing BPA structural analog replacements have increased in response to growing public concern over adverse effects of BPA. Although humans are regularly exposed to a mixture of bisphenols, few studies have examined effects of prenatal exposure to BPA alternatives or bisphenol mixtures. In the present study, we investigate the effect of exposure to an environmentally-relevant, low-dose (150 ug/kg body weight per day) mixture of BPA, BPS, and BPF during gestation on the brain transcriptome in Long-Evans pups and dams using Tag RNA-sequencing. We also examined the association between dam licking and grooming, which also has enduring effects on pup neural development, and the transcriptomes. Associations between licking and grooming and the transcriptome were region-specific, with the hypothalamus having the greatest number of differentially expressed genes associated with licking and grooming in both dams and pups. Prenatal bisphenol exposure also had region-specific effects on gene expression and pup gene expression was affected more robustly than dam gene expression. In dams, the prelimbic cortex had the greatest number of differentially expressed genes asso-ciated with prenatal bisphenol exposure. Prenatal bisphenol exposure changed the expression of over 2000 genes in pups, with the majority being from the pup amygdala. We used Gene Set Enrichment Analysis (GSEA) to asses enrichment of gene ontology biological processes for each region. Top GSEA terms were diverse and varied by brain region and included processes known to have strong associations with steroid hormone regulation, cilium -related terms, metabolic/biosynthetic process terms, and immune terms. Finally, hypothesis-driven analysis of genes related to estrogen response, parental behavior, and epigenetic regulation of gene expression revealed region-specific expression associated with licking and grooming and bisphenol exposure that were distinct in dams and pups. These data highlight the effects of bisphenols on multiple physiological process that are highly dependent on timing of exposure (prenatal vs. adulthood) and brain region, and reiterate the contributions of multiple environmental and experiential factors in shaping the brain.

OBJECTIVE:The at-risk mental state (ARMS) for psychosis has long played a key role in diathesis-stress models of schizophrenia. More recent studies, however, have called for extending the boundaries of the ARMS construct beyond attenuated psychosis in nonhelp-seeking samples to include not only other vulnerability indicators but also protective factors related to genotype, mental health, personality, and cognition.METHOD:Accordingly, we assessed in a sample of 100 college students, the ARMS construct with the Brief Prodromal Questionnaire (PQ-B) for psychosis, in conjunction with measures of positive mental health, childhood adversity, psychiatric symptoms, personality traits, social cognition, and genetic variables derived from assays of the serotonin transporter (5-HTTLPR) and the brain-derived neurotrophic factor (BDNF).RESULTS:Higher PQ-B scores correlated positively with vulnerability indicators of childhood adversity and heightened levels of a wide variety of psychiatric symptoms but correlated negatively with protective factors of better overall mental health, social cognition as well as with a distinct NEO profile marked by reduced neuroticism and elevated agreeableness and conscientiousness. Multivariate analyses indicated that a composite ARMS measure comprised of PQ-B scores plus anxiety and depression symptoms revealed significant genotype differences, with lowest risk and highest resilience for allelic carriers of 5-HTTLPR-short and BDNF Met polymorphisms.CONCLUSIONS:Results provided support for extending the ARMS construct, pointing to important contributions of personality, social cognition, and genes that support neural plasticity in mitigating vulnerability and enhancing resilience and well-being.

The hippocampus is a highly plastic brain region sensitive to environmental stress. It shows dynamic changes in epigenetic marks associated with stress related learning. Previous work has shown that acute stress induces substantial transient changes in histone H3 lysine 9 trimethylation (H3K9me3). Moreover, increased H3K9me3 is enriched in hippocampal gene deserts accumulating within endogenous retroviruses and transposable elements. We have found that in response to acute glucocorticoid treatment, a similar change in global H3K9me3 is observed. However, when localized we found that H3K9me3 is markedly decreased at B2 short interspersed nuclear elements but not within intracisternal-A particle endogenous retroviruses. Further, decreased H3K9me3 valence within B2 elements was associated with increased transcript abundance. These data demonstrate the capacity for acute glucocorticoids to mobilize transposable elements via epigenetic unmasking. Reconciled with previous findings following acute stress, this suggests the capacity for mobile elements to potentially function as novel regulators given their dynamic regulation by stress and glucocorticoids.

A quality nest can buffer pups from the cold climate in typical laboratory housing by insulating them from cool ambient air and facilitating pup huddling during early life when many thermal regulation strategies are not yet developed. The limited nesting material (LBN) manipulation prevents the dam from constructing a quality nest. In the present study, we investigate whether LBN presents a thermal challenge to pups across the first two postnatal weeks. Behavioral thermal regulation (huddling), physiological thermogenesis (activation of brown adipose tissue; BAT), changes in cellular metabolism (mitochondrial biogenesis) in peripheral and central tissues, and maternal behavior were measured in environments with LBN or abundant bedding on postnatal day (P) 2, P6, P10, and P14. The huddle of LBN litters had greater area, greater perimeter, and reduced circularity, and more pups visible. Control male pups were visible longer than control female pups during home cage recordings and LBN pups were visible longer than control pups. Heart weight relative to body weight was higher in LBN pups after P2. LBN affected BAT, but not white adipose tissue (WAT), activation in a sex and age-specific manner, with reductions in UCP1 expression after P2. Pups appear especially affected by LBN on P6, when mitochondrial DNA copy number was reduced in WAT. Mitochondrial DNA copy number was reduced in LBN pups in the hippocampus but not the brainstem. Our data provide evidence of changes in indices of thermal regulation and cellular metabolism in LBN pups which may be indicative of changes in energy allocation during development.

Individuals vary greatly in their mental health and these differences may play a critical role in stress resistance, risk reduction and illness recovery. Here we ask how these differences may be related to normal variation in personality and genotype. One hundred healthy college students completed measures of mental health (Mental Health Continuum-Short Form [MHC-SF]), personality (NEO Five Factor Inventory) and adverse childhood experiences. Participants also provided saliva samples, genotyped for both the serotonin transporter (5-HTTLPR) and the brain-derived neurotrophic factor (BDNF), each assayed for naturally occurring polymorphisms, 5-HTTLPR (short/long) and BDNF (valine/methionine). Mental health correlated strongly with the NEO triad of conscientiousness-extraversion-neuroticism, with largest contributions to MHC-SF scores for conscientiousness, followed by extraversion and then neuroticism. The personality trait interaction of extraversion × conscientiousness uniquely accounted for approximately 44.22% 44.62% of the variance in MHC-SF scores. Polygenic comparisons showed a significant gene × gene interaction, with highest mental health for 5-HTTLPR-S, Met carriers. Together these results provided support for distinct yet interacting roles of personality and genetics in the phenotypical expression of mental health.

Oxytocin is important for postnatal developmental experiences for mothers, infants, and transactions between them. Oxytocin is also implicated in adult affiliative behaviors, including social buffering of stress. There is evidence for connections between early life experience and adult oxytocin system functioning, but effects of early experience on behavioral, endocrine, and neurophysiological outcomes related to adult social buffering are not well explored. We use a limited bedding and nesting (LBN) material paradigm as an environmental disruption of early experiences and assessed central oxytocin systems in brain regions related to hypothalamic-pituitary-adrenal (HPA) axis regulation (paraventricular nucleus of the hypothalamus, amygdala, hippocampus). We also assessed developmentally-appropriate social behaviors and HPA reactivity during social buffering testing in adulthood. LBN litters had larger huddles and more pups visible compared to control litters during the first two weeks of life. LBN also altered the developmental trajectory of oxytocin-expressing cells and oxytocin receptor cells, with increases in oxytocin receptor cells at P15 in LBN pups. By adulthood, LBN females had more and LBN males had fewer oxytocin and oxytocin receptor cells in these areas compared to sex-matched controls. Adult LBN females, but not LBN males, had behavioral changes during social interaction and social buffering testing. The sex-specific effects of early experience on central oxytocin systems and social behavior may contribute to female resilience to early life adversity.