Prenatal pregnancy-related anxiety predicts boys' ADHD symptoms via placental C-reactive protein

Prenatal maternal negative life events associated with child emotional and behavioral problems in the French EDEN cohort

INTRODUCTION

Prenatal negative life events (NLEs) have been linked to adverse health outcomes in children. However, few studies examine this relationship during late childhood using trajectory analyses. Additionally, the impact of specific NLEs domains on child development remains unclear. This study aims to longitudinally explore the association between NLEs (cumulative score and specific NLEs domains) and child outcomes from birth to late childhood.

METHODS

1135 mother-child pairs from the French EDEN cohort were followed from 24 to 28 weeks of pregnancy up to 11 years of age. Maternal self-reports of prenatal NLEs were collected immediately after birth, then analyzed as a cumulative score and by NLEs domain. Children's emotional and behavioral symptoms were assessed at 4 timepoints through the Strengths and Difficulties Questionnaire.

RESULTS

Children of mothers exposed to ≥3 NLEs were more likely to follow trajectories of high levels of peer relationship problems (aOR [95 % CI] = 5.69 [1.74-18.69]), emotional symptoms (aOR [95 % CI] = 3.05 [1.08-8.63]), and conduct problems (aOR [95 %] = 3.53 [1.20-10.42]). Among the domains of NLEs, only events related to housing, finance, and living conditions were significantly associated with high emotional and behavioral difficulties trajectories (aOR [95%CI] = 2.71[1.26-5.81]).

LIMITATIONS

Potential attrition bias due to a higher dropout rate for children experiencing early indications of emotional and behavioral difficulties.

CONCLUSION

Findings support the relationship between prenatal NLEs and child outcomes, underscoring the importance of assessing prenatal stressors across life domains to identify mothers who might be in need of support.

Sex Differences in Stress Susceptibility as a Key Mechanism Underlying Depression Risk

PURPOSE OF REVIEW

Although females are at relatively greater risk for a variety of disorders, including depression, the biological mechanisms underlying this striking health disparity remain unclear. To address this issue, we highlight sex differences in stress susceptibility as a key mechanism potentially driving this effect and describe the interacting inflammatory, hormonal, epigenomic, and social-environmental mechanisms involved.

RECENT FINDINGS

Using the Social Signal Transduction Theory of Depression as a theoretical framework, women's elevated risk for depression may stem from a tight link between life stress, inflammation, and depression in women. Further, research finds hormonal contraceptive use alters cortisol and inflammatory reactivity to acute stress in ways that may increase depression risk in females. Finally, beyond established epigenetic mechanisms, mothers may transfer risk for depression to their female offspring through stressful family environments, which influence stress generation and stress-related gene expression. Together, these findings provide initial, biologically plausible clues that may help explain the relatively greater risk for depression in females vs. males. Looking forward, much more research is needed to address the longstanding underrepresentation of females in biomedical research on the biology of stress and depression.

Attention-deficit/hyperactivity disorder and the menstrual cycle: Theory and evidence

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that exhibits striking sex differences in symptoms, prevalence, and associated problems across development. Etiological factors and mechanisms underlying these sex differences remain one of the most understudied aspects of this disorder. The current paper seeks to provide a novel theoretical framework for understanding this phenomenon by reviewing evidence that females with ADHD may experience a "double whammy" of organizational and activational pubertal hormonal effects. We propose a novel theory of activational effects of cyclical circulating ovarian hormones on ADHD with increasing risk at times of rapid declines in estrogen. These declines may decrease executive function and trait control at two points of the cycle characterized by biphasic affective risk: (1) increases in approach/risk-taking behaviors at mid-cycle (periovulatory) and (2) increases in avoidance/negative affect perimenstrually. Low estrogen and control may then interact with increases in positive and negative affect, respectively, to increase hyperactivity-impulsivity symptoms post-ovulation and inattention symptoms perimenstrually. These interactions may be exacerbated by organizational pubertal effects on relatively overdeveloped limbic circuitry and adolescent-specific social pressures magnified in females with ADHD.

Developmental Neuroendocrinology of Early-Life Stress: Impact on Child Development and Behavior

Our internal balance, or homeostasis, is threatened or perceived as threatened by stressful stimuli, the stressors. The stress system is a highly conserved system that adjusts homeostasis to the resting state. Through the concurrent activation of the hypothalamic-pituitary-adrenal axis and the locus coeruleus/norepinephrine-autonomic nervous systems, the stress system provides the appropriate physical and behavioral responses, collectively termed as "stress response", to restore homeostasis. If the stress response is prolonged, excessive or even inadequate, several acute or chronic stress-related pathologic conditions may develop in childhood, adolescence and adult life. On the other hand, earlylife exposure to stressors has been recognized as a major contributing factor underlying the pathogenesis of non-communicable disorders, including neurodevelopmental disorders. Accumulating evidence suggests that early-life stress has been associated with an increased risk for attention deficit hyperactivity disorder and autism spectrum disorder in the offspring, although findings are still controversial. Nevertheless, at the molecular level, early-life stressors alter the chemical structure of cytosines located in the regulatory regions of genes, mostly through the addition of methyl groups. These epigenetic modifications result in the suppression of gene expression without changing the DNA sequence. In addition to DNA methylation, several lines of evidence support the role of non-coding RNAs in the evolving field of epigenetics. In this review article, we present the anatomical and functional components of the stress system, discuss the proper, in terms of quality and quantity, stress response, and provide an update on the impact of early-life stress on child development and behavior.

Pregnant women's mental health during the COVID-19 pandemic according to the trimester of pregnancy

AIM

This study aimed to analyse the psychological impact of the COVID-19 pandemic on pregnant women according to the pregnancy trimester, comparing their psychopathological symptomatology, pregnancy-specific stress, resilience and perceived stress to those of women pregnant before the pandemic.

METHODS

A total of 797 pregnant women participated in the study, one group of 393 women pregnant before the pandemic and the other of 404 women pregnant during the pandemic. Student-t test was used to analyse continuous data and the Chi-square test was used for categorical data.

RESULTS

Psychopathological symptomatology was significantly higher in six subscales of the SCL-90-R in pregnant women during COVID-19: somatisation, interpersonal sensitivity, depression, anxiety, phobic anxiety, obsessions-compulsions, mainly on the first two trimesters. There is also a higher level of pregnancy-specific stress in pregnant women during the pandemic on the first two trimesters, most likely due to the hypervigilance and fears related to the COVID-19 disease. Nevertheless, perceived stress, usually elevated during pregnancy, was lower in women pregnant during the pandemic in comparison to those pregnant before, as a positive consequence of being on lockdown and diminishing the exposure to daily stressful situations.

CONCLUSIONS

Knowing the struggles these women go through during each trimester of pregnancy can be the key to a better health professional-patient relationship, consequently having a positive impact on their mental and physical health.

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

Prospective associations between various prenatal exposures to maternal psychological stress and neurodevelopment in children within 24 months after birth

BACKGROUND

There is increasing evidence that prenatal exposure to maternal psychological distress may be a factor influencing offspring neurodevelopment, but stress type-dependent effects of maternal psychological distress on offspring neurodevelopment in early childhood have yet to be fully elucidated. Additionally, although positive maternal mental health exerts potential effects in protecting against adverse health outcomes, few investigators have considered the effects of positive maternal mental health on offspring neurodevelopment in early childhood.

AIMS

To determine the associations between various prenatal exposures to maternal psychological distress and positive life-event experiences and offspring neurodevelopment within 24 months of age.

METHODS

A total of 4412 mother-child dyads were recruited from the Shanghai Maternal-Child Pairs Cohort (Shanghai MCPC). Maternal perceived stress, negative life-event stress, positive life-event experiences around the time of conception (i.e., three months prior to and after conception) were assessed at 12-16 gestational weeks, and maternal anxiety and depressive symptoms were assessed at 32-36 gestational weeks. We measured children's neurodevelopment using the Ages and Stages Questionnaire, Third Edition (ASQ-3) at two, six, 12, and 24 months postnatally. We then exploited generalized linear models to estimate the associations between prenatal maternal psychological distress and positive life-event experiences and children's neurodevelopment at the above periods, and generalized linear mixed models were applied to assess the associations between maternal psychological distress and positive life-event experiences and suspected developmental delay (SDD) in children within 24 months after birth based on a longitudinal design.

RESULTS

Maternal perceived stress and negative life-event stress around the time of conception, and anxiety and depressive symptoms during late pregnancy were negatively associated with scores of children's neurodevelopment at two, six, 12, and 24 months of age; while maternal life-event experiences were positively associated with scores of children's neurodevelopment. Longitudinal analysis revealed that higher levels of maternal negative life-event stress and depressive symptoms augmented the risk of SDD in personal-social (OR = 1.435, 1.681). Mothers who experienced higher levels of positive life-event experiences exhibited a reduced risk of SDD in gross motor and personal-social domains (OR = 0.373, 0.350).

CONCLUSIONS

Prenatal exposure to maternal psychological distress is negatively associated with children's neurodevelopment in early childhood depending upon the type of distress. Maternal positive life-event experiences around the time of conception appeared to present potential benefits for child neurodevelopment.

Interaction between isolated maternal hypothyroxinemia and pregnancy-related anxiety on preschooler's internalizing and externalizing problems: A birth cohort study

BACKGROUND

Isolated maternal hypothyroxinemia (IMH) and pregnancy-related anxiety may increase the risk of offspring's emotional and behavioral problems, but little is known about their potential interactive effect on preschoolers' internalizing and externalizing problems.

METHODS

We conducted a large prospective cohort study in Ma'anshan Maternal and Child Health Hospital between May 2013 and September 2014. There were a total of 1372 mother-child pairs from the Ma'anshan birth cohort (MABC) included in this study. IMH was defined as the thyroid-stimulating hormone (TSH) level within the normal reference range (2.5-97.5th percentile) and the free thyroxine (FT₄) level below the 2.5th percentile, and negative TPOAb. The pregnancy-related anxiety questionnaire (PRAQ) was used to assess women's pregnancy-related anxiety status in the first (1-13 weeks), second (14-27 weeks) and third (after 28 weeks) trimesters of pregnancy. The Achenbach Child Behavior Checklist (CBCL/1.5-5) was used to assess preschoolers' internalizing and externalizing problems.

RESULTS

Preschoolers born of mothers with IMH and anxiety had an increased risk of anxious/depressed (OR = 6.40, 95% CI 1.89-21.68), somatic complaints (OR = 2.69, 95% CI 1.01-7.20), attention problems (OR = 2.95, 95% CI 1.00-8.69) and total problems (OR = 3.40, 95% CI 1.60-7.21). Particularly, mothers with IMH and anxiety was associated with an increased risk of preschool girls' anxious/depressed (OR = 8.14, 95% CI 1.74-38.08), withdrawn (OR = 7.03, 95% CI 2.25-21.92), internalizing problems (OR = 2.66, 95% CI 1.00-7.08), and total problems (OR = 5.50, 95% CI 2.00-15.10).

CONCLUSIONS

IMH and pregnancy-related anxiety during pregnancy may synergistically increase the risk of internalizing and externalizing problems in preschooler children. This interaction is distinct in internalizing problems of preschool girls.

C-Reactive Protein (CRP): A Potent Inflammation Biomarker in Psychiatric Disorders

An increasing number of studies have investigated the role of inflammation in psychiatric disorders, by demonstrating how an altered/dysfunctional immunological and inflammatory system may underpin a psychiatric condition. Particularly, several studies specifically investigated the role of a neuroinflammatory biomarker, named C-reactive protein (CRP), in psychiatric disorders. Overall, even though scientific literature so far published still does not appear definitive, CRP is more likely reported to be elevated in several psychiatric disorders, including schizophrenia, mood disorders, anxiety disorders and post-traumatic stress disorder. Moreover, a low-grade inflammation (CRP >3 mg/L) has been more likely observed in a subgroup of patients affected with a more severe psychopathological symptomatology, more treatment resistance and worst clinical mental illness course, strengthening the hypothesis of the need for a different clinical and prognostic characterization based on this concomitant neuroinflammatory predisposition. However, even though further research studies are needed to confirm this preliminary evidence, CRP may represent a potential clinical routine biomarker which could be integrated in the clinical routine practice to better characterize clinical picture and course as well as address clinicians towards a personalized treatment.

Sex-specific association between placental inflammatory cytokine mRNA expression and preschoolers' behavioral development: The Ma'anshan birth cohort study

BACKGROUND

Placental inflammation may contribute to brain abnormalities and childhood neuropsychiatric disorders, but limited knowledge is available on the association of placental inflammatory cytokine levels and offspring's behavioral development. This study aimed to examine the sex-specific association between placental inflammatory cytokine mRNA expression and preschoolers' behavioral development.

METHODS

3474 pregnant women were recruited as the initial study population in the Ma'anshan birth cohort (MABC) study. Placentas (n = 2519) were collected during childbirth, and the mRNA expression of IL-8, IL-1β, CRP, TNF-α, IL-6, IL-10, and IL-4 was assessed. The Child Behavior Checklist 1.5-5 (CBCL 1.5-5) was used to assess children's behavioral development at 4 years old. A T-score ≥ 60 on summary scales or a score ≥ 65 on syndrome scales was regarded as the borderline clinical range. Multiple linear regression models and binary logistic regression models were applied to explore the sex-specific associations between placental inflammatory cytokines mRNA transcript levels and preschoolers' behavioral development.

RESULTS

Sex-specific associations between placental inflammatory cytokines mRNA expression and preschoolers' behavioral development were observed. There was a positive association between IL-8 and CBCL scores for boys on anxious/depressed problems, aggressive behaviors, externalizing problems and total problems. Logistic regression models showed that high levels of IL-8 were associated with a higher risk of girls' emotionally reactive problems and sleep problems compared to low/medium levels. High TNF-α was correlated with increased sleep problem scores in boys, and medium TNF-α (vs. low levels) was associated with an increased risk of girls' externalizing problems. Medium levels of CRP, IL-1β, and IL-6 were found to be associated with a decreased risk of girls' behavioral problems compared to low/high levels. For anti-inflammatory cytokines, medium IL-10 and IL-4 (vs. low levels) were observed to be associated with a lower risk of internalizing problems in boys and externalizing problems in girls, respectively. High IL-10 was correlated with decreased attention problem scores in boys.

CONCLUSION

This study indicates that placental inflammatory cytokine mRNA expression of IL-8, CRP, TNF-α, IL-1β, IL-4 and IL-10 may be associated with preschoolers' behavioral development in a sex-specific manner.

The impact of maternal high-fat diet on offspring neurodevelopment

A maternal high-fat diet affects offspring neurodevelopment with long-term consequences on their brain health and behavior. During the past three decades, obesity has rapidly increased in the whole human population worldwide, including women of reproductive age. It is known that maternal obesity caused by a high-fat diet may lead to neurodevelopmental disorders in their offspring, such as autism spectrum disorder, attention deficit hyperactivity disorder, anxiety, depression, and schizophrenia. A maternal high-fat diet can affect offspring neurodevelopment due to inflammatory activation of the maternal gut, adipose tissue, and placenta, mirrored by increased levels of pro-inflammatory cytokines in both maternal and fetal circulation. Furthermore, a maternal high fat diet causes gut microbial dysbiosis further contributing to increased inflammatory milieu during pregnancy and lactation, thus disturbing both prenatal and postnatal neurodevelopment of the offspring. In addition, global molecular and cellular changes in the offspring's brain may occur due to epigenetic modifications including the downregulation of brain-derived neurotrophic factor (BDNF) expression and the activation of the endocannabinoid system. These neurodevelopmental aberrations are reflected in behavioral deficits observed in animals, corresponding to behavioral phenotypes of certain neurodevelopmental disorders in humans. Here we reviewed recent findings from rodent models and from human studies to reveal potential mechanisms by which a maternal high-fat diet interferes with the neurodevelopment of the offspring.

Developmental Stressors Induce Innate Immune Memory in Microglia and Contribute to Disease Risk

Many types of stressors have an impact on brain development, function, and disease susceptibility including immune stressors, psychosocial stressors, and exposure to drugs of abuse. We propose that these diverse developmental stressors may utilize a common mechanism that underlies impaired cognitive function and neurodevelopmental disorders such as schizophrenia, autism, and mood disorders that can develop in later life as a result of developmental stressors. While these stressors are directed at critical developmental windows, their impacts are long-lasting. Immune activation is a shared pathophysiology across several different developmental stressors and may thus be a targetable treatment to mitigate the later behavioral deficits. In this review, we explore different types of prenatal and perinatal stressors and their contribution to disease risk and underlying molecular mechanisms. We highlight the impact of developmental stressors on microglia biology because of their early infiltration into the brain, their critical role in brain development and function, and their long-lived status in the brain throughout life. Furthermore, we introduce innate immune memory as a potential underlying mechanism for developmental stressors' impact on disease. Finally, we highlight the molecular and epigenetic reprogramming that is known to underlie innate immune memory and explain how similar molecular mechanisms may be at work for cells to retain a long-term perturbation after exposure to developmental stressors.

Neuropsychiatric disorders: An immunological perspective

Neuropsychiatric diseases have traditionally been studied from brain, and mind-centric perspectives. However, mounting epidemiological and clinical evidence shows a strong correlation of neuropsychiatric manifestations with immune system activation, suggesting a likely mechanistic interaction between the immune and nervous systems in mediating neuropsychiatric disease. Indeed, immune mediators such as cytokines, antibodies, and complement proteins have been shown to affect various cellular members of the central nervous system in multitudinous ways, such as by modulating neuronal firing rates, inducing cellular apoptosis, or triggering synaptic pruning. These observations have in turn led to the exciting development of clinical therapies aiming to harness this neuro-immune interaction for the treatment of neuropsychiatric disease and symptoms. Besides the clinic, important theoretical fundamentals can be drawn from the immune system and applied to our understanding of the brain and neuropsychiatric disease. These new frameworks could lead to novel insights in the field and further potentiate the development of future therapies to treat neuropsychiatric disease.

Gender-specific associations of pregnancy-related anxiety with placental epigenetic patterning of glucocorticoid response genes and preschooler's emotional symptoms and hyperactivity

BACKGROUD

We have recently reported that maternal prenatal pregnancy-related anxiety predicts preschoolers' emotional and behavioral development in a gender-dependent manner. This study aims to test for this gender-specific effect in a different cohort and investigate whether the gender difference was specific to placental methylation of genes regulating glucocorticoids.

METHODS

A total of 2405 mother-child pairs from the Ma'anshan Birth Cohort Study were included in present study. The maternal pregnancy-related anxiety symptoms were evaluated with the Pregnancy-Related Anxiety Questionnaire in the third trimester of pregnancy. Child neurobehavior was assessed with the Strengths and Difficulties Questionnaire at 4 years old. Placental methylation of FKBP5, NR3C1 and HSD11B2 genes was quantified using the MethylTarget approach in 439 pregnant women. After exploratory factor analysis, the associations between methylation factor scores and pregnancy-related anxiety and child neurobehavior were examined using logistic regression analysis.

RESULTS

After controlling for confounding factors, pregnancy-related anxiety in the third trimester of pregnancy increased the risk of hyperactivity only in boys and emotional symptoms only in girls. Decreased scores of the factor characterized by FKBP5 methylation were associated with maternal pregnancy-related anxiety only in boys. Furthermore, increased scores of the factors characterized by NR3C1 and HSD11B2 methylation were associated with hyperactivity (NR3C1: adjusted OR = 1.80, 95%CI = 1.15-2.83) and emotional symptoms (HSD11B2: adjusted OR = 0.53, 95%CI = 0.29-0.97; NR3C1: adjusted OR = 1.64, 95%CI = 1.03-2.59) only in boys. However, the scores of the factor characterized by FKBP5, NR3C1 and HSD11B2 did not mediate the relationship between maternal pregnancy-related anxiety and preschoolers' emotional symptoms and hyperactivity.

CONCLUSIONS

Our results suggested that pregnancy-related anxiety in the third trimester of pregnancy predicted preschoolers' emotional symptoms and hyperactivity in a gender-dependent manner. Although we did not find the mediation role of the placental methylation of genes regulating glucocorticoids, we found it was associated with both maternal pregnancy-related anxiety and preschoolers' emotional symptoms and hyperactivity in a gender-dependent manner.

Maternal immune activation and neuroinflammation in human neurodevelopmental disorders

Maternal health during pregnancy plays a major role in shaping health and disease risks in the offspring. The maternal immune activation hypothesis proposes that inflammatory perturbations in utero can affect fetal neurodevelopment, and evidence from human epidemiological studies supports an association between maternal inflammation during pregnancy and offspring neurodevelopmental disorders (NDDs). Diverse maternal inflammatory factors, including obesity, asthma, autoimmune disease, infection and psychosocial stress, are associated with an increased risk of NDDs in the offspring. In addition to inflammation, epigenetic factors are increasingly recognized to operate at the gene-environment interface during NDD pathogenesis. For example, integrated brain transcriptome and epigenetic analyses of individuals with NDDs demonstrate convergent dysregulated immune pathways. In this Review, we focus on the emerging human evidence for an association between maternal immune activation and childhood NDDs, including autism spectrum disorder, attention-deficit/hyperactivity disorder and Tourette syndrome. We refer to established pathophysiological concepts in animal models, including immune signalling across the placenta, epigenetic 'priming' of offspring microglia and postnatal immune-brain crosstalk. The increasing incidence of NDDs has created an urgent need to mitigate the risk and severity of these conditions through both preventive strategies in pregnancy and novel postnatal therapies targeting disease mechanisms.

Maternal prenatal choline and inflammation effects on 4-year-olds' performance on the Wechsler Preschool and Primary Scale of Intelligence-IV

Maternal gestational inflammation from infection, obesity, depression, and adverse childhood experiences negatively affects offspring cognitive development. Choline is a key nutrient in fetal brain development. We investigated whether higher maternal plasma choline concentrations have a positive association with offspring cognition, specifically processing speed, in the presence of inflammation. Forty-eight children were evaluated at 4 years of age. Processing Speed Composite Score on the Wechsler Preschool & Primary Scales of Intelligence was the principal outcome. Maternal C-reactive protein (CRP), a marker of inflammation, and choline plasma concentration had been measured at 16 weeks' gestation. Choline concentrations >7.07μM were compared to lower levels. Mothers with lower choline levels reported more depression and stress. Head circumference was larger for neonates of mothers with higher choline levels. In analyses with maternal CRP, higher maternal choline was associated with higher offspring Processing Speed Composite Scores for both sexes. For males, higher maternal choline competed with the negative association of maternal CRP on Processing Speed. Higher Processing Speed was related to the child's behavioral ratings, with fewer Withdrawn Problems on the Child Behavior Checklist 1 ½-5 years at 4 years and higher Infant Behavior Questionnaire Orienting/Regulation at 3 months of age, consistent with persistent developmental effects. Higher processing speed and decreased problems in social withdrawal are positively associated with prenatal maternal choline. Both lower processing speed and social withdrawal problems are precursors to later mental difficulties. Choline supplementation in pregnancy may mitigate effects of maternal inflammation that contribute to problems in offspring's' cognition and behavior.

Prenatal stress-induced disruptions in microbial and host tryptophan metabolism and transport

The aromatic amino acid tryptophan (Trp) is a precursor for multiple metabolites that can steer proper immune and neurodevelopment as well as social behavior in later life. Dysregulation in the Trp metabolic pathways and abundance of Trp or its derivatives, including indoles, kynurenine (Kyn), and particularly serotonin, has been associated with behavioral deficits and neuropsychiatric disorders including autism spectrum disorders (ASD) and schizophrenia. Previously, we have shown that prenatal stress (PNS) alters placental Trp and serotonin, and reduces Trp-metabolizing members of the maternal colonic microbiota. Given that PNS also results in alterations in offspring neurodevelopment, behavior and immune function, we hypothesized that PNS affects Trp metabolism and transport in both the maternal and fetal compartments, and that these alterations continue into adolescence. We surmised that this is due to reductions in Trp-metabolizing microbes that would otherwise reduce the Trp pool under normal metabolic conditions. To test this, pregnant mice were exposed to a restraint stressor and gene expression of enzymes involved in Trp and serotonin metabolism were measured. Specifically, tryptophan 2,3-dioxygenase, aryl hydrocarbon receptor, and solute carrier proteins, were altered due to PNS both prenatally and postnatally. Additionally, Parasutterella and Bifidobacterium, which metabolize Trp in the gut, were reduced in both the dam and the offspring. Together, the reductions of Trp-associated microbes and concomitant dysregulation in Trp metabolic machinery in dam and offspring suggest that PNS-induced Trp metabolic dysfunction may mediate aberrant fetal neurodevelopment.

The impact of (ab)normal maternal environment on cortical development

The cortex in the mammalian brain is the most complex brain region that integrates sensory information and coordinates motor and cognitive processes. To perform such functions, the cortex contains multiple subtypes of neurons that are generated during embryogenesis. Newly born neurons migrate to their proper location in the cortex, grow axons and dendrites, and form neuronal circuits. These developmental processes in the fetal brain are regulated to a large extent by a great variety of factors derived from the mother - starting from simple nutrients as building blocks and ending with hormones. Thus, when the normal maternal environment is disturbed due to maternal infection, stress, malnutrition, or toxic substances, it might have a profound impact on cortical development and the offspring can develop a variety of neurodevelopmental disorders. Here we first describe the major developmental processes which generate neuronal diversity in the cortex. We then review our knowledge of how most common maternal insults affect cortical development, perturb neuronal circuits, and lead to neurodevelopmental disorders. We further present a concept of selective vulnerability of cortical neuronal subtypes to maternal-derived insults, where the vulnerability of cortical neurons and their progenitors to an insult depends on the time (developmental period), place (location in the developing brain), and type (unique features of a cell type and an insult). Finally, we provide evidence for the existence of selective vulnerability during cortical development and identify the most vulnerable neuronal types, stages of differentiation, and developmental time for major maternal-derived insults.