Maternal hormonal milieu influence on fetal brain development

Mild Gestational Hypothyroidism in Mice Has Transient Developmental Effects and Long-Term Consequences on Neuroendocrine Systems

Background: Thyroid hormones (TH) play a key role in fetal brain development. While severe thyroid dysfunction, has been shown to cause neurodevelopmental and reproductive disorders, the rising levels of TH-disruptors in the environment in the past few decades have increased the need to assess effects of subclinical (mild) TH insufficiency during gestation. Since embryos do not produce their own TH before mid-gestation, early development processes rely on maternal production. Notably, the reproductive network governed by gonadotropin-releasing hormone (GnRH) neurons develops during this critical period. Methods: The risk of mild maternal hypothyroidism on the development of GnRH neurons and long-term effect on neuroendocrine function in the offspring was investigated using a mouse model of gestational hypothyroidism induced by methimazole (MMI) treatment. Results: MMI treatment during gestation led to reduced litter size, consistent with increased miscarriages due to hypothyroidism. E12/13 embryos, collected from MMI-treated dams, had a decreased number of GnRH neurons, but the migration of the remaining GnRH neurons was normal. Cell proliferation was reduced in the vomeronasal organ (VNO), correlating with the reduced number of GnRH neurons detected in this region. Using a GnRH cell line confirmed attenuated proliferation in the absence of T3. Pups born from hypothyroid mothers had normal postweaning growth and estrus cycles, yet adult offspring had significantly more cells expressing estrogen receptor alpha in the arcuate nucleus. Notably, by adulthood, GnRH cell number and distribution was comparable with nontreated controls indicating that compensatory mechanisms occurred after E13. Conclusion: Overall, our work shows that mild TH disruption during gestation transiently affects proliferation of the pool of GnRH neurons within the VNO and has a long-term impact on neuroendocrine systems.

Personalized Antenatal Corticosteroid Therapy and Central Nervous System Development: Reflections on the Gold Standard of Fetomaternal Therapy

BACKGROUND

The term "fetal programming" refers to the effects of endogenous and exogenous corticosteroids, whether received from the mother or the fetus, on brain development and the hypothalamic-pituitary-adrenal axis reset. The authors of this narrative review examine the WHO's guidelines for prenatal corticosteroids in pregnant women who are at high risk of premature delivery. These guidelines are regarded as the best available for preventing late-life problems resulting from preterm.

METHODS

In order to find full-text publications published in peer-reviewed journals between 1990 and 2023 that were written in English, the authors searched PubMed, Scopus, Cochrane Library, and Web of Science.

RESULTS

The authors highlight the possible adverse long-term effects of prenatal corticosteroid medication on human brain development and function. This pharmacological feature is therapeutically significant because there is less evidence in the scientific literature regarding the potential role that the timing, mode, and dosage of exogenous steroid treatment may have in neurological illnesses down the road.

CONCLUSIONS

The authors expect that these studies will shed light on the relationship between specially designed prenatal corticosteroid therapy and the molecular mechanisms underlying the prenatal programming of neurodevelopment in childhood and adulthood.

Steroidogenic pathway in girls diagnosed with autism spectrum disorders

The diagnostic prevalence of autism spectrum disorders (ASD) shows boys to be more affected than girls. Due to this reason, there is a lack of research including and observing ASD girls. Present study was aimed to detect hormones of steroidogenesis pathway in prepubertal girls (n = 16) diagnosed with ASD and sex and age matched neurotypical controls (CTRL, n = 16). Collected plasma served for detection of conjugated and unconjugated steroids using gas chromatography tandem-mass spectrometry. We observed higher levels of steroids modulating ionotropic receptors, especially, GABAergic steroids and pregnenolone sulfate in ASD group. Concentration of many steroids throughout the pathway tend to be higher in ASD girls compared to CTRL. Pregnenolone and its isomers together with polar progestins and androstanes, i.e. sulfated steroids, were found to be higher in ASD group in comparison with CTRL group. Based on steroid product to precursor ratios, ASD group showed higher levels of sulfated/conjugated steroids suggesting higher sulfotransferase or lower steroid sulfatase activity and we also obtained data indicating lower activity of steroid 11β-hydroxylase compared to CTRL group despite higher corticosterone level observed in ASD. These findings need to be generalized in future studies to examine both genders and other age groups.

The mother-child interface: A neurobiological metamorphosis

From the start of pregnancy, mother and child induce reciprocal neurobiological changes in the brain that will prove critical for neurodevelopment and survival of both. Molecular communication between mother and fetus is constantly active and persists even after the fetus starts to synthesize its hormones in late gestation. Intriguingly, some mother and fetus exchange cells remain in the other's brain and body with long-lasting effects and memories that do not follow the laws of classical genetics but involve complex epigenetic mechanisms. After childbirth, mother and child go through a transitional phase, a sort of limbo in which both will have a peculiar functioning profile, which is adaptive for contingencies but also renders them vulnerable. The interplay between these two "limbo" states allows for an easier transition to the subsequent phases of development. In this review, we will trace mother's and child's path from pregnancy to the months following birth and, in particular, unravel i) the key features of pregnancy and brain development and the reciprocal influences; ii) how a transitory pattern of functioning characterize mother and child, moving them toward more flexible and evolved forms; and iii) how mother and fetus act during childbirth to promote neuroprotection, pain reduction, and neurophysiological changes. Therefore, this review covers a wide range of topics, integrating neuroanatomical, neurological, biochemical, neurophysiological, and psychological studies in a meaningful way, trying to integrate them in a holistic view of the mother-child interface that is usually neglected.

Do Parental Hormone Levels Synchronize During the Prenatal and Postpartum Periods? A Systematic Review

Physiological synchrony is the phenomenon of linked physiological processes among two or more individuals. Evidence of linkage between dyads has been found among a broad range of physiological indices, including the endocrine systems. During the transition to parenthood, both men and women undergo hormonal changes that facilitate parenting behavior. The present review sought to address the question as to whether hormonal synchronization occurs among expecting or new parents. A systematic literature search yielded 13 eligible records. The evidence of cortisol synchrony during the prenatal period, with additional testosterone, prolactin, and progesterone covariations in the time leading up to childbirth, was found to be most significant. During the postpartum period, parental synchrony was reported for oxytocin, testosterone, and cortisol levels. The implications of these covariations were found to translate into adaptive parenting behaviors and the facilitation of romantic bond. Associations with infant development were also reported, suggesting far-reaching effects of hormonal synchrony outside the parental dyad. The results highlight the importance of physiological interrelatedness during this sensitive period, underscoring the need for further research in this field. In view of the limited data available in this research domain, we have put forward a framework for future studies, recommending the adoption of standardized research protocols and repeated collections of specimens.

Mothers in stress: Hair cortisol of mothers living in marginalised Roma communities and the role of socioeconomic disadvantage

Roma living in marginalised communities are among the most disadvantaged groups in Slovakia. Socioeconomic disadvantage is associated with higher hair cortisol concentrations (HCC), including in parents. The aim of this study is therefore to assess differences in HCC, reflecting the levels of stress, between mothers living in MRCs and from the majority population, to assess the association of socioeconomic disadvantage with HCC, and whether disadvantage mediates the MRC/majority differences in HCC. Participants were mothers of children aged 15-18 months old living in MRCs (N=61) and from the Slovak majority population (N=90). During preventive paediatric visits, visits at community centres and home visits, hair samples and data by questionnaire were collected. HCC differed significantly between mothers living in MRCs and mothers from the majority population, with the mean HCC value being twice as high in mothers living in MRCs (22.98 (95% confidence interval, CI, 15.70-30.30) vs. 11.76 (8.34-15.20), p<0.05). HCC was significantly associated with education, household equipment and household overcrowding, but not with billing, socioeconomic stress and social support. The difference in HCC between mothers living in MRCs and mothers from the majority population was partially mediated by poor house equipment, such as no access to running water, no flushing toilet or no bathroom (the indirect effect of B=7.63 (95% CI: 2.12-13.92)). Practitioners and policymakers should be aware of high stress levels among mothers living in MRCs and aim at enhancing their living and housing conditions.

Prenatal exposure to air pollution and maternal depression: Combined effects on brain aging and mental health in young adulthood

INTRODUCTION

Both maternal depression problems during pregnancy and prenatal exposure to air pollution have been associated with changes in the brain as well as worse mood and anxiety in the offspring in adulthood. However, it is not clear whether these effects are independent or whether and how they might interact and impact the brain age and mental health of the young adult offspring.

METHODS

A total of 202 mother-child dyads from a prenatal birth cohort were assessed for maternal depression during pregnancy through self-report questionnaires administered in the early 90s, exposure to air pollutants (Sulfur dioxide [SO2], nitrogen oxides [NOx], and suspended particle matter [SPM]) during each trimester based on maternal address and air quality data, mental health of the young adult offspring (28-30 years of age; 52% men, all of European ancestry) using self-report questionnaires for depression (Beck Depression Inventory), mood dysregulation (Profile of Mood States), anxiety (State-Trait Anxiety Inventory), and psychotic symptoms (Schizotypal Personality Questionnaire), and brain age, estimated from structural magnetic resonance imaging (MRI) and previously published neuroanatomical age prediction model using cortical thickness maps. The brain age gap estimate (BrainAGE) was computed by subtracting structural brain age from chronological age. Trajectories of exposure to air pollution during pregnancy were assessed using Growth Mixture Modeling. The interactions of prenatal depression and prenatal exposure to air pollutants on adult mental health and BrainAGE were assessed using hierarchical linear regression.

RESULTS

We revealed two distinct trajectories of exposure to air pollution during pregnancy: "early exposure," characterized by high exposure during the first trimester, followed by a steady decrease, and "late exposure," characterized by low exposure during the first trimester, followed by a steady increase in the exposure during the subsequent trimesters. Maternal depression during the first half of pregnancy interacted with NOX exposure trajectory, predicting mood dysregulation and schizotypal symptoms in young adults. In addition, maternal depression during the second half of pregnancy interacted with both NOx and SO2 exposure trajectories, respectively, and predicted BrainAGE in young adults. In those with early exposure to NOx, maternal depression during pregnancy was associated with worse mental health and accelerated brain aging in young adulthood. In contrast, in those with early exposure to SO2, maternal depression during pregnancy was associated with slower brain aging in young adulthood.

CONCLUSIONS

Our findings provide the first evidence of the combined effects of prenatal exposure to air pollution and maternal depression on mental health outcomes and brain age in young adult offspring. Moreover, they point out the importance of the timing and trajectory of the exposure during prenatal development.

Fetal sexual dimorphism of maternal thyroid function parameters during pregnancy, a single center retrospective real-world study

Introduction

Thyroid function during pregnancy fluctuates with gestational weeks, seasons and other factors. However, it is currently unknown whether there is a fetal sex-specific thyroid function in pregnant women. The purpose of this study was to investigate the fetal sex differences of maternal thyroid-stimulating hormone (TSH) and free thyroxine (FT4) in pregnant women.

Methods

This single-center retrospective real-world study was performed by reviewing the medical records of pregnant women who received regular antenatal health care and delivered liveborn infants in Shanghai First Maternity and Infant Hospital (Pudong branch), from Aug. 18, 2013 to Jul. 18, 2020. Quantile regression was used to evaluate the relationship between various variables and TSH and FT4 concentrations. The quantile regression also evaluated the sex impact of different gestational weeks on the median of TSH and FT4.

Results

A total of 69,243 pregnant women with a mean age of 30.36 years were included. 36197 (52.28%) deliveries were boys. In the three different trimesters, the median levels (interquartile range) of TSH were 1.18 (0.66, 1.82) mIU/L and 1.39 (0.85, 2.05) mIU/L, 1.70 (1.19, 2.40) mIU/L; and the median levels (interquartile range) of FT4 were 16.63 (15.16, 18.31) pmol/L, 14.09 (12.30, 16.20) pmol/L and 13.40 (11.52, 14.71) pmol/L, respectively. The maternal TSH upper limit of reference ranges was decreased more in mothers with female fetuses during gestational weeks 7 to 12, while their FT4 upper limit of the reference ranges was increased more than those with male fetuses. After model adjustment, the median TSH level was 0.11 mIU/L lower (P <0.001), and FT4 level was 0.14 pmol/L higher (P <0.001) for mothers with female fetuses than those with male fetuses during gestational weeks 9 to 12.

Discussion

We identified sexual dimorphism in maternal thyroid function parameters, especially during 9-12 weeks of pregnancy. Based on previous research, we speculated that it may be related to the higher HCG levels of mothers who were pregnant with girls during this period. However, longitudinal studies are needed to determine if fetal sex differences impact the maternal thyroid function across pregnancy.

Intersection of Aging and Particulate Matter 2.5 Exposure in Real World: Effects on Inflammation and Endocrine Axis Activities in Rats

Exposure to particulate matter 2.5 (PM2.5) is detrimental to multiple organ systems. Given the factor that aging also alters the cellularity and response of immune system and dysfunction of hypothalamic-pituitary-adrenal, -gonad and -thyroid axes, it is imperative to investigate whether chronic exposure to PM2.5 interacts with aging in these aspects. In this study, two-months-old Sprague-Dawley rats were exposed to real world PM2.5 for 16 months. PM2.5 exposure diminished the relative numbers of CD4+ T cells and CD8+ T cells and increased the relative number of B cells in the peripheral blood of male rats. Conversely, only reduced relative number of CD4+ T cells was seen in the blood of female rats. These shifts resulted in elevated levels of proinflammatory factors interleukin-6 and tumor necrosis factor-α in the circulatory systems of both sex, with females also evidencing a rise in interleukin-1β levels. Moreover, heightened interleukin-6 was solely discernible in the hippocampus of female subjects, while increased tumor necrosis factor-α concentrations were widespread in female brain regions but confined to the male hypothalamus. Notable hormonal decreases were observed following PM2.5 exposure in both sex. These comprised declines in biomolecules such as corticotrophin-releasing hormone and cortisol, generated by the hypothalamic-pituitary-adrenal axis, and thyroid-releasing hormone and triiodothyronine, produced by the hypothalamic-pituitary-thyroid axis. Hormonal elements such as gonadotropin-releasing hormone, luteinizing hormone, and follicle-stimulating hormone, derived from the hypothalamic-pituitary-gonad axis, were also diminished. Exclusive to male rats was a reduction in adrenocorticotropic hormone levels, whereas a fall in thyroid-stimulating hormone was unique to female rats. Decreases in sex-specific hormones, including testosterone, estradiol, and progesterone, were also noted. These findings significantly enrich our comprehension of the potential long-term health repercussions associated with PM2.5 interaction particularly among the aging populace.

A Review of Fetal Development in Pregnancies with Maternal Type 2 Diabetes Mellitus (T2DM)-Associated Hypothalamic-Pituitary-Adrenal (HPA) Axis Dysregulation: Possible Links to Pregestational Prediabetes

Research has identified fetal risk factors for adult diseases, forming the basis for the Developmental Origins of Health and Disease (DOHaD) hypothesis. DOHaD suggests that maternal insults during pregnancy cause structural and functional changes in fetal organs, increasing the risk of chronic diseases like type 2 diabetes mellitus (T2DM) in adulthood. It is proposed that altered maternal physiology, such as increased glucocorticoid (GC) levels associated with a dysregulated hypothalamic-pituitary-adrenal (HPA) axis in maternal stress and T2DM during pregnancy, exposes the fetus to excess GC. Prenatal glucocorticoid exposure reduces fetal growth and programs the fetal HPA axis, permanently altering its activity into adulthood. This programmed HPA axis is linked to increased risks of hypertension, cardiovascular diseases, and mental disorders in adulthood. With the global rise in T2DM, particularly among young adults of reproductive age, it is crucial to prevent its onset. T2DM is often preceded by a prediabetic state, a condition that does not show any symptoms, causing many to unknowingly progress to T2DM. Studying prediabetes is essential, as it is a reversible stage that may help prevent T2DM-related pregnancy complications. The existing literature focuses on HPA axis dysregulation in T2DM pregnancies and its link to fetal programming. However, the effects of prediabetes on HPA axis function, specifically glucocorticoid in pregnancy and fetal outcomes, are not well understood. This review consolidates research on T2DM during pregnancy, its impact on fetal programming via the HPA axis, and possible links with pregestational prediabetes.

Reference intervals for thyroid function from the fifth to seventh day of life in twin-pregnancy preterm neonates: an 8-year retrospective study

PURPOSE

The immature and developing hypothalamic-pituitary-thyroid axis leads to different levels of thyroid function in twin neonates, including free thyroxine (FT4), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) levels. No reference intervals for twins have been established until now. To compensate for this lack, we collected data and established this standard across different gestational ages (GAs) and sexes.

METHODS

A total of 273 pairs of neonates admitted to the NICU in Southeast China from 2015 to 2022 were included. Each pair was divided into Neonate A (relatively heavy birth weight (BW)) and Neonate B (relatively light BW). Their thyroid functions were analyzed to establish reference intervals and comparisons were made stratified by GA and sex.

RESULTS

The FT3, FT4, and TSH reference intervals in twin neonates with a GA of 26-36 weeks were as follows: Neonate A and B: 3.59 ± 0.99 and 3.57 ± 1.00 pmol/L; Neonate A and B: 17.03 ± 5.16 and 16.77 ± 5.29 pmol/L; and Neonate A and B: 4.097 ± 3.688 and 4.674 ± 4.850 mlU/L, respectively. There were significant differences between serum FT3 and FT4 reference intervals and GA (p < 0.05). The serum FT3 and FT4 reference intervals for male neonates were lower than those for female neonates in the 29-32-week group (p < 0.05).

CONCLUSION

This was the first study, to our knowledge, to establish reference intervals for thyroid function in twin neonates from the fifth to seventh day of life, which will be beneficial for the diagnosis and management of congenital hypothyroidism.

Intrapartum exposure to synthetic oxytocin, maternal BMI, and neurodevelopmental outcomes in children within the ECHO consortium

BACKGROUND

Synthetic oxytocin (sOT) is frequently administered during parturition. Studies have raised concerns that fetal exposure to sOT may be associated with altered brain development and risk of neurodevelopmental disorders. In a large and diverse sample of children with data about intrapartum sOT exposure and subsequent diagnoses of two prevalent neurodevelopmental disorders, i.e., attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), we tested the following hypotheses: (1) Intrapartum sOT exposure is associated with increased odds of child ADHD or ASD; (2) associations differ across sex; (3) associations between intrapartum sOT exposure and ADHD or ASD are accentuated in offspring of mothers with pre-pregnancy obesity.

METHODS

The study sample comprised 12,503 participants from 44 cohort sites included in the Environmental Influences on Child Health Outcomes (ECHO) consortium. Mixed-effects logistic regression analyses were used to estimate the association between intrapartum sOT exposure and offspring ADHD or ASD (in separate models). Maternal obesity (pre-pregnancy BMI ≥ 30 kg/m2) and child sex were evaluated for effect modification.

RESULTS

Intrapartum sOT exposure was present in 48% of participants. sOT exposure was not associated with increased odds of ASD (adjusted odds ratio [aOR] 0.86; 95% confidence interval [CI], 0.71-1.03) or ADHD (aOR 0.89; 95% CI, 0.76-1.04). Associations did not differ by child sex. Among mothers with pre-pregnancy obesity, sOT exposure was associated with lower odds of offspring ADHD (aOR 0.72; 95% CI, 0.55-0.96). No association was found among mothers without obesity (aOR 0.97; 95% CI, 0.80-1.18).

CONCLUSIONS

In a large, diverse sample, we found no evidence of an association between intrapartum exposure to sOT and odds of ADHD or ASD in either male or female offspring. Contrary to our hypothesis, among mothers with pre-pregnancy obesity, sOT exposure was associated with lower odds of child ADHD diagnosis.

Pregestational Prediabetes Induces Maternal Hypothalamic-Pituitary-Adrenal (HPA) Axis Dysregulation and Results in Adverse Foetal Outcomes

Maternal type 2 diabetes mellitus (T2DM) has been shown to result in foetal programming of the hypothalamic-pituitary-adrenal (HPA) axis, leading to adverse foetal outcomes. T2DM is preceded by prediabetes and shares similar pathophysiological complications. However, no studies have investigated the effects of maternal prediabetes on foetal HPA axis function and postnatal offspring development. Hence, this study investigated the effects of pregestational prediabetes on maternal HPA axis function and postnatal offspring development. Pre-diabetic (PD) and non-pre-diabetic (NPD) female Sprague Dawley rats were mated with non-prediabetic males. After gestation, male pups born from the PD and NPD groups were collected. Markers of HPA axis function, adrenocorticotropin hormone (ACTH) and corticosterone, were measured in all dams and pups. Glucose tolerance, insulin and gene expressions of mineralocorticoid (MR) and glucocorticoid (GR) receptors were further measured in all pups at birth and their developmental milestones. The results demonstrated increased basal concentrations of ACTH and corticosterone in the dams from the PD group by comparison to NPD. Furthermore, the results show an increase basal ACTH and corticosterone concentrations, disturbed MR and GR gene expression, glucose intolerance and insulin resistance assessed via the Homeostasis Model Assessment (HOMA) indices in the pups born from the PD group compared to NPD group at all developmental milestones. These observations reveal that pregestational prediabetes is associated with maternal dysregulation of the HPA axis, impacting offspring HPA axis development along with impaired glucose handling.

The effect of prenatal maternal distress on offspring brain development: A systematic review

BACKGROUND

Prenatal maternal distress can negatively affect pregnancy outcomes, yet its impact on the offspring's brain structure and function remains unclear. This systematic review summarizes the available literature on the relationship between prenatal maternal distress and brain development in fetuses and infants up to 12 months of age.

METHODS

We searched Central, Embase, MEDLINE, PsycINFO, and PSYNDEXplus for studies published between database inception and December 2023. Studies were included if prenatal maternal anxiety, stress, and/or depression was assessed, neuroimaging was used to examine the offspring, and the offspring's brain was imaged within the first year of life. The quality of the included studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-II.

RESULTS

Out of the 1516 studies retrieved, 71 met our inclusion criteria. Although the studies varied greatly in their methodology, the results generally pointed to structural and functional aberrations in the limbic system, prefrontal cortex, and insula in fetuses and infants prenatally exposed to maternal distress.

CONCLUSIONS

The hippocampus, amygdala, and prefrontal cortex have a high density of glucocorticoid receptors, which play a key role in adapting to stressors and maintaining stress-related homeostasis. We thus conclude that in utero exposure to maternal distress prompts these brain regions to adapt by undergoing structural and functional changes, with the consequence that these alterations increase the risk for developing a neuropsychiatric illness later on. Future research should investigate the effect of providing psychological support for pregnant women on the offspring's early brain development.

The research landscape concerning environmental factors in neurodevelopmental disorders: Endocrine disrupters and pesticides-A review

In recent years, environmental epidemiology and toxicology have seen a growing interest in the environmental factors that contribute to the increased prevalence of neurodevelopmental disorders, with the purpose of establishing appropriate prevention strategies. A literature review was performed, and 192 articles covering the topic of endocrine disruptors and neurodevelopmental disorders were found, focusing on polychlorinated biphenyls, polybrominated diphenyl ethers, bisphenol A, and pesticides. This study contributes to analyzing their effect on the molecular mechanism in maternal and infant thyroid function, essential for infant neurodevelopment, and whose alteration has been associated with various neurodevelopmental disorders. The results provide scientific evidence of the association that exists between the environmental neurotoxins and various neurodevelopmental disorders. In addition, other possible molecular mechanisms by which pesticides and endocrine disruptors may be associated with neurodevelopmental disorders are being discussed.

Factors and Mechanisms of Thyroid Hormone Activity in the Brain: Possible Role in Recovery and Protection

Thyroid hormones (THs) are essential in normal brain development, and cognitive and emotional functions. THs act through a cascade of events including uptake by the target cells by specific cell membrane transporters, activation or inactivation by deiodinase enzymes, and interaction with nuclear thyroid hormone receptors. Several thyroid responsive genes have been described in the developing and in the adult brain and many studies have demonstrated a systemic or local reduction in TH availability in neurologic disease and after brain injury. In this review, the main factors and mechanisms associated with the THs in the normal and damaged brain will be evaluated in different regions and cellular contexts. Furthermore, the most common animal models used to study the role of THs in brain damage and cognitive impairment will be described and the use of THs as a potential recovery strategy from neuropathological conditions will be evaluated. Finally, particular attention will be given to the link observed between TH alterations and increased risk of Alzheimer's Disease (AD), the most prevalent neurodegenerative and dementing condition worldwide.

Early menarche and other endocrine disrupting effects of per- and polyfluoroalkyl substances (PFAS) in adolescents from Northern Norway. The Fit Futures study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) comprise a large group of chemicals that are ubiquitous in the environment and include recognized persistent organic pollutants. The aim of this cross-sectional study was to investigate possible endocrine disrupting effects of different PFAS in adolescents.

METHODS

Serum concentrations of PFAS, thyroid, parathyroid and steroid hormones were measured in 921 adolescents aged 15-19 years in the Fit Futures study, Northern Norway. The questionnaire included data on self-reported age at menarche and puberty development score (PDS). Multiple linear and logistic regression analyses and principle component analyses (PCA) were used to assess associations of PFAS with hormones concentrations and puberty indices.

RESULTS

In girls, total PFAS (∑PFAS), perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), perfluorodecanoate (PFDA) were positively associated with dehydroepiandrosterone sulfate (DHEAS) and negatively associated with 11-deoxycorticosterone (11-DOC)/DHEAS ratio. In boys, the associations with 11-DOC/DHEAS ratio were positive for ∑PFAS, perfluoroheptanoate (PFHpA), perfluoroheptane sulfonate (PFHpS), PFOA, and PFOS. Perfluoroundecanoate (PFUnDA) was negatively associated with free thyroxine (fT4) and free triiodothyronine (fT3) in boys. PFNA and PFDA were also negatively associated with fT3 in boys. Serum parathyroid hormone concentration (PTH) was negatively associated with ∑PFAS and perfluorohexane sulfonate (PFHxS) in girls, and with PFOS in boys. PFDA and PFUnDA were positively associated with early menarche, while ∑PFAS and PFOA were positively associated with PDS in boys. No associations of PFAS with serum testosterone, follicle-stimulating hormone, or luteinizing hormone were found in either sex. In girls, PFOA was positively associated with free testosterone index (FTI). In boys, PFOA was positively associated with androstendione and 17-OH-progesterone, while PFHpA was positively associated with estradiol.

CONCLUSIONS

Serum concentrations of several PFAS were associated with parathyroid and steroid hormones in both sexes, and with thyroid hormones in boys, as well as with early menarche in girls and higher PDS in boys.

Early developmental risks for tobacco addiction: A probabilistic epigenesis framework

Considerable progress has been made in elucidating the relationships between early life psychobiological and environmental risk factors and the development of tobacco addiction. However, a comprehensive understanding of the heterogeneity in tobacco addiction phenotypes requires integrating research findings. The probabilistic epigenesis meta-theory offers a valuable framework for this integration, considering systemic, multilevel, developmental, and evolutionary perspectives. In this paper, we critically review relevant research on early developmental risks associated with tobacco addiction and highlight the integrative heuristic value of the probabilistic epigenesis framework for this research. For this, we propose a four-level systems approach as an initial step towards integration, analyzing complex interactions among different levels of influence. Additionally, we explore a coaction approach to examine key interactions between early risk factors. Moreover, we introduce developmental pathways to understand interindividual differences in tobacco addiction risk during development. This integrative approach holds promise for advancing our understanding of tobacco addiction etiology and informing potentially effective intervention strategies.

Obesity in pregnancy-Long-term effects on offspring hypothalamic-pituitary-adrenal axis and associations with placental cortisol metabolism: A systematic review

Obesity, affecting one in three pregnant women worldwide, is not only a major obstetric risk factor. The resulting low-grade inflammation may have a long-term impact on the offspring's HPA axis through dysregulation of maternal, placental and fetal corticosteroid metabolism, and children born of obese mothers have increased risk of diabetes and cardiovascular disease. The long-term effects of maternal obesity on offspring neurodevelopment are, however, undetermined and could depend on the specific effects on placental and fetal cortisol metabolism. This systematic review evaluates how maternal obesity affects placental cortisol metabolism and the offspring's HPA axis. Pubmed, Embase and Scopus were searched for original studies on maternal BMI, obesity, and cortisol metabolism and transfer. Fifteen studies were included after the screening of 4556 identified records. Studies were small with heterogeneous exposures and outcomes. Two studies found that maternal obesity reduced placental HSD11β2 activity. In one study, umbilical cord blood cortisol levels were affected by maternal BMI. In three studies, an altered cortisol response was consistently seen among offspring in childhood (n = 2) or adulthood (n = 1). Maternal BMI was not associated with placental HSD11β1 or HSD11β2 mRNA expression, or placental HSD11β2 methylation. In conclusion, high maternal BMI is associated with reduced placental HSD11β2 activity and a dampened cortisol level among offspring, but the data is sparse. Further investigations are needed to clarify whether the HPA axis is affected by prenatal factors including maternal obesity and investigate if adverse effects can be ameliorated by optimising the intrauterine environment.

Amniotic fluid cortisol predicts neonatal and infant development in non-stressed rhesus monkeys: Implications for prenatal stress

Prenatal stress adversely affects offspring development, with fetal cortisol (CORT) exposure being a primary hypothesized mechanism for stress-induced developmental deficits. Fetal CORT exposure can be assessed via measurements in amniotic fluid. However, in humans, amniocentesis is typically only performed for clinical reasons such as karyotyping; thus, amniotic fluid CORT cannot be obtained from a random sample. To test the hypothesis that fetal CORT exposure predicts neonatal and infant development in healthy primates, we measured amniotic fluid CORT in N = 18 healthy rhesus macaque (Macaca mulatta) dams (50:50 female:male infants) between 80 and 124 days gestation (mean ± SEM = 98.3 ± 2.9 days out of 165 days gestational length; i.e., second trimester). Maternal hair cortisol concentrations (HCCs) were assessed throughout pregnancy and lactation. Offspring were assessed for physical growth, neurological development, cognitive development, and HCCs across postnatal days 30-180. Controlling for gestational age at amniocentesis, higher amniotic fluid CORT significantly predicted slower infant growth rate (g/day) in the first 30 days (β = -0.19; R2 = 0.71, p = .008), poorer sensorimotor scores on the day 30 neonatal assessment (β = -0.28; R2 = 0.76, p = .015), and longer time to complete training (β = 0.48; R2 = 0.54, p = .026), but better performance (β = 0.91; R2 = 0.60, p = .011) on a discrimination cognitive task at 120-180 days. Amniotic fluid CORT was not associated with maternal or infant HCCs. Although these results are correlative, they raise the intriguing possibility that fetal CORT exposure in non-stress-exposed primates, as measured by amniotic fluid CORT, programs multiple aspects of neonatal and infant development. On the other hand, amniotic fluid CORT may not relate to chronic CORT levels in either mothers or infants when assessed by hair sampling.

Prenatal exposure to common plasticizers: a longitudinal study on phthalates, brain volumetric measures, and IQ in youth

Exposure to phthalates, used as plasticizers and solvents in consumer products, is ubiquitous. Despite growing concerns regarding their neurotoxicity, brain differences associated with gestational exposure to phthalates are understudied. We included 775 mother-child pairs from Generation R, a population-based pediatric neuroimaging study with prenatal recruitment, who had data on maternal gestational phthalate levels and T1-weighted magnetic resonance imaging in children at age 10 years. Maternal urinary concentrations of phthalate metabolites were measured at early, mid-, and late pregnancy. Child IQ was assessed at age 14 years. We investigated the extent to which prenatal exposure to phthalates is associated with brain volumetric measures and whether brain structural measures mediate the association of prenatal phthalate exposure with IQ. We found that higher maternal concentrations of monoethyl phthalate (mEP, averaged across pregnancy) were associated with smaller total gray matter volumes in offspring at age 10 years (β per log10 increase in creatinine adjusted mEP = -10.7, 95%CI: -18.12, -3.28). Total gray matter volumes partially mediated the association between higher maternal mEP and lower child IQ (β for mediated path =-0.31, 95%CI: -0.62, 0.01, p = 0.05, proportion mediated = 18%). An association of higher monoisobutyl phthalate (mIBP) and smaller cerebral white matter volumes was present only in girls, with cerebral white matter volumes mediating the association between higher maternal mIBP and lower IQ in girls. Our findings suggest the global impact of prenatal phthalate exposure on brain volumetric measures that extends into adolescence and underlies less optimal cognitive development.

A Critical Review on the Opportunity to Use Placenta and Innovative Biomonitoring Methods to Characterize the Prenatal Chemical Exposome

Adverse effects associated with chemical exposures during pregnancy include several developmental and reproductive disorders. However, considering the tens of thousands of chemicals present on the market, the effects of chemical mixtures on the developing fetus is still likely underestimated. In this critical review, we discuss the potential to apply innovative biomonitoring methods using high-resolution mass spectrometry (HRMS) on placenta to improve the monitoring of chemical exposure during pregnancy. The physiology of the placenta and its relevance as a matrix for monitoring chemical exposures and their effects on fetal health is first outlined. We then identify several key parameters that require further investigations before placenta can be used for large-scale monitoring in a robust manner. Most critical is the need for standardization of placental sampling. Placenta is a highly heterogeneous organ, and knowledge of the intraplacenta variability of chemical composition is required to ensure unbiased and robust interindividual comparisons. Other important variables include the time of collection, the sex of the fetus, and mode of delivery. Finally, we discuss the first applications of HRMS methods on the placenta to decipher the chemical exposome and describe how the use of placenta can complement biofluids collected on the mother or the fetus.

The Effects of Combined Exposure to Bisphenols and Perfluoroalkyls on Human Perinatal Stem Cells and the Potential Implications for Health Outcomes

The present study investigates the impact of two endocrine disruptors, namely Bisphenols (BPs) and Perfluoroalkyls (PFs), on human stem cells. These chemicals leach from plastic, and when ingested through contaminated food and water, they interfere with endogenous hormone signaling, causing various diseases. While the ability of BPs and PFs to cross the placental barrier and accumulate in fetal serum has been documented, the exact consequences for human development require further elucidation. The present research work explored the effects of combined exposure to BPs (BPA or BPS) and PFs (PFOS and PFOA) on human placenta (fetal membrane mesenchymal stromal cells, hFM-MSCs) and amniotic fluid (hAFSCs)-derived stem cells. The effects of the xenobiotics were assessed by analyzing cell proliferation, mitochondrial functionality, and the expression of genes involved in pluripotency and epigenetic regulation, which are crucial for early human development. Our findings demonstrate that antenatal exposure to BPs and/or PFs may alter the biological characteristics of perinatal stem cells and fetal epigenome, with potential implications for health outcomes at birth and in adulthood. Further research is necessary to comprehend the full extent of these effects and their long-term consequences.

Hypothyroidism in Adult Women: The Utility of Targeted vs Universal Thyroid Screening

Hypothyroidism is a common disease that is more prevalent in female populations. The purpose of this paper is to discuss the evidence, risks, and benefits of screening asymptomatic women for hypothyroidism. There is lack of evidence to support clinical management of asymptomatic individuals with an elevated TSH and normal serum thyroxine levels. Patients with subclinical hypothyroidism, especially the elderly, are at risk of overtreatment. Given these considerations, the majority of US and UK professional organizations do not support universal screening. Many do offer caveats for special groups, including pregnant people, who may need screening if there are clinical symptoms or family history of autoimmune disease. In conclusion, targeted screening may be best recommended based on risk factors, symptoms, and clinical suspicion, rather than at a universal level.

Long-term adverse neurodevelopmental outcomes of discordant twins delivered at term: A nationwide population-based study

OBJECTIVE

To evaluate long-term adverse neurodevelopmental outcomes of discordant twins delivered at term.

DESIGN

Retrospective cohort study.

SETTING

Nationwide (Republic of Korea).

POPULATION

All twin children delivered at term between 2007 and 2010.

METHODS

The study population was divided into two groups according to inter-twin birthweight discordancy: the 'concordant twin group', twin pairs with inter-twin birthweight discordancy less than 20%; and the 'discordant twin group', twin pairs with inter-twin birthweight discordancy of 20% or more. The risk of long-term adverse neurodevelopmental outcomes was compared between the concordant twin group and the discordant twin group. Long-term adverse neurodevelopmental outcomes between smaller and larger twin children within twin pairs were further analysed. The composite adverse neurodevelopmental outcome was defined as the presence of at least one of the following: motor developmental delay, cognitive developmental delay, autism spectrum disorders/attention deficit hyperactivity disorders, tics/stereotypical behaviour or epileptic/febrile seizure.

MAIN OUTCOME MEASURES

Long-term adverse neurodevelopmental outcome.

RESULTS

Of 22 468 twin children (11 234 pairs) included, 3412 (15.19%) twin children were discordant. The risk of composite adverse neurodevelopmental outcome was higher in the discordant twin group than in the concordant twin group (adjusted hazard ratio [HR] 1.13, 95% CI 1.03-1.24). The long-term adverse neurodevelopmental outcomes were not significantly different between smaller and larger twin children in discordant twin pairs (adjusted HR 1.01, 95% CI 0.81-1.28).

CONCLUSION

In twin pairs delivered at term, an inter-twin birthweight discordancy of 20% or greater was associated with long-term adverse neurodevelopmental outcomes; and long-term adverse neurodevelopmental outcomes were not significantly different in smaller or larger twin children in discordant twin pairs.

Local Thyroid Hormone Action in Brain Development

Proper brain development essentially depends on the timed availability of sufficient amounts of thyroid hormone (TH). This, in turn, necessitates a tightly regulated expression of TH signaling components such as TH transporters, deiodinases, and TH receptors in a brain region- and cell-specific manner from early developmental stages onwards. Abnormal TH levels during critical stages, as well as mutations in TH signaling components that alter the global and/or local thyroidal state, result in detrimental consequences for brain development and neurological functions that involve alterations in central neurotransmitter systems. Thus, the question as to how TH signaling is implicated in the development and maturation of different neurotransmitter and neuromodulator systems has gained increasing attention. In this review, we first summarize the current knowledge on the regulation of TH signaling components during brain development. We then present recent advances in our understanding on how altered TH signaling compromises the development of cortical glutamatergic neurons, inhibitory GABAergic interneurons, cholinergic and dopaminergic neurons. Thereby, we highlight novel mechanistic insights and point out open questions in this evolving research field.

Iodine Deficiency, Maternal Hypothyroxinemia and Endocrine Disrupters Affecting Fetal Brain Development: A Scoping Review

This scoping review critically discusses the publications of the last 30 years on the impact of mild to moderate iodine deficiency and the additional impact of endocrine disrupters during pregnancy on embryonal/fetal brain development. An asymptomatic mild to moderate iodine deficiency and/or isolated maternal hypothyroxinemia might affect the development of the embryonal/fetal brain. There is sufficient evidence underlining the importance of an adequate iodine supply for all women of childbearing age in order to prevent negative mental and social consequences for their children. An additional threat to the thyroid hormone system is the ubiquitous exposure to endocrine disrupters, which might exacerbate the effects of iodine deficiency in pregnant women on the neurocognitive development of their offspring. Ensuring adequate iodine intake is therefore essential not only for healthy fetal and neonatal development in general, but it might also extenuate the effects of endocrine disruptors. Individual iodine supplementation of women of childbearing age living in areas with mild to moderate iodine deficiency is mandatory as long as worldwide universal salt iodization does not guarantee an adequate iodine supply. There is an urgent need for detailed strategies to identify and reduce exposure to endocrine disrupters according to the "precautional principle".

Iodine and Thyroid Maternal and Fetal Metabolism during Pregnancy

Thyroid hormones and iodine are required to increase basal metabolic rate and to regulate protein synthesis, long bone growth and neuronal maturation. They are also essential for protein, fat and carbohydrate metabolism regulation. Imbalances in thyroid and iodine metabolism can negatively affect these vital functions. Pregnant women are at risk of hypo or hyperthyroidism, in relation to or regardless of their medical history, with potential dramatic outcomes. Fetal development highly relies on thyroid and iodine metabolism and can be compromised if they malfunction. As the interface between the fetus and the mother, the placenta plays a crucial role in thyroid and iodine metabolism during pregnancy. This narrative review aims to provide an update on current knowledge of thyroid and iodine metabolism in normal and pathological pregnancies. After a brief description of general thyroid and iodine metabolism, their main modifications during normal pregnancies and the placental molecular actors are described. We then discuss the most frequent pathologies to illustrate the upmost importance of iodine and thyroid for both the mother and the fetus.

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.

Stress, Thyroid Dysregulation, and Thyroid Cancer in Children and Adolescents: Proposed Impending Mechanisms

Stress is a potential catalyst for thyroid dysregulation through cross-communication of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid (HPT) axes. Stress and stressors exposure motivates molecular mechanisms affecting compound feedback loops of the HPT axis. While there is evidence of connection between stress and thyroid dysregulation, the question whether this connection is implicated in the development of thyroid cancer (TC) remains unanswered. In view of the rising incidence of TC in both adults and children alongside the increasing stress in our modern society, there is a need to understand possible interrelations between stress, thyroid dysregulation, and TC. Prolonged glucocorticoid secretion due to stress interferes with immune system response by altering the cytokines, inducing low-grade chronic inflammation, and suppressing function of immune-protective cells. Chronic inflammation is a risk factor linked to TC. The role of autoimmunity has been a matter of controversy. However, there is epidemiological connection between autoimmune thyroid disease (AITD) and TC; patients with AITD show increased incidence in papillary thyroid carcinoma (PTC), and those with TC show a high prevalence of intrathyroidal lymphocyte infiltration and thyroid autoantibodies. Timing and duration-dependent exposure to specific endocrine disrupting chemicals (EDCs) has an impact on thyroid development, function, and proliferation, leading to thyroid disease and potentially cancer. Thyroid hormone imbalance, chronic inflammation, and EDCs are potential risk factors for oxidative stress. Oxygen free radicals are capable of causing DNA damage via stimulation of the mitogen-activating protein kinase or phosphatidylinositol-3-kinase and/or nuclear factor kB pathways, resulting in TC-associated gene mutations such as RET/PTC, AKAP9-BRAF, NTRK1, RAASF, PIK3CA, and PTEN. Stressful events during the critical periods of prenatal and early life can influence neuroendocrine regulation and induce epigenetic changes. Aberrant methylation of tumor suppressor genes such as P16INK4A, RASSF, and PTEN is associated with PTC; histone H3 acetylation is shown to be higher in TC, and thyroid-specific noncoding RNAs are downregulated in PTC. This review focuses on the above proposed mechanisms that potentially lead to thyroid tumorigenesis with the aim to help in the development of novel prognostic and therapeutic strategies for TC.

A critical review of the recent concept of artificial mechanical uterus design in relation to the maternal microbiome: An Update to past researches

The microbiome in the female reproductive tract plays an essential role in immune modulation and reproductive health. However, various microbes become established during pregnancy, the balance of which plays a crucial role in embryonic development and healthy births. The contribution of disturbances in the microbiome profile to embryo health is poorly understood. A better understanding of the relationship between reproductive outcomes and the vaginal microbiota is needed to optimize the chances of healthy births. In this regards, microbiome dysbiosis refers to conditions in which the pathways of communication and balance within the normal microbiome are imbalanced due to the intrusion of pathogenic microorganisms into the reproductive system. This review summarizes the current state of knowledge on the natural human microbiome, with a focus on the natural uterine microbiome, mother-to-child transmission, dysbiosis, and the pattern of microbial change in pregnancy and parturition, and reviews the effects of artificial uterus probiotics during pregnancy. These effects can be studied in the sterile environment of an artificial uterus, and microbes with potential probiotic activity can be studied as a possible therapeutic approach. The artificial uterus is a technological device or biobag used as an incubator, allowing extracorporeal pregnancy. Establishing beneficial microbial communities within the artificial womb using probiotic species could modulate the immune system of both the fetus and the mother. The artificial womb could be used to select the best strains of probiotic species to fight infection with specific pathogens. Questions about the interactions and stability of the most appropriate probiotics, as well as dosage and duration of treatment, need to be answered before probiotics can be a clinical treatment in human pregnancy.

Effects of Excessive Iodine on the BDNF-TrkB Signaling Pathway and Related Genes in Offspring of EAT Rats

Excess iodine can cause autoimmune thyroiditis (AIT) in women, but it is unclear whether this has any implications for neurodevelopmental mechanisms in offspring. We studied the effects of experimental autoimmune thyroiditis (EAT) rats with different amounts of iodine intake on offspring brain development via the brain-derived neurotrophic factor (BDNF)-tropomycin receptor kinase B (TrkB) signaling pathway, because BDNF plays an important role in neurodevelopment. Rats in three thyroglobulin (Tg) immunized groups with varying iodine intakes (Tg (100 µg/L iodine), Tg + High-iodine I group (Tg + HI, 20 mg/L iodine), and Tg + High-iodine II group (Tg + HII, 200 mg/L iodine)) were injected with 800 µg Tg once every 2 weeks for 3 times. Rats in the control group (NI, 100 µg/L iodine) were immunized with saline. Arsenic-cerium catalytic spectrophotometry was used to measure urine iodine levels. The lymphocytic infiltration in the thyroids was observed by histopathological studies. Thyroid autoantibodies levels were measured using radioimmunoassay. The norepinephrine (NE) contents were measured by an enzyme-linked immunosorbent assay. The levels of the BDNF-TrkB signaling pathway and related genes were measured by quantitative real-time PCR and Western blot. Urinary iodine levels increased as iodine intake increased. Lymphocytes were significantly aggravated in Tg-immunized rats. Serum thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) levels were clearly elevated in Tg-immunized rats. Tg-immune groups had significantly lower NE levels. The BDNF-TrkB signaling pathway and related gene mRNA and protein levels were found to be significantly lower in Tg-immune groups with higher iodine levels. Maternal AIT may reduce the levels of certain neurodevelopmental mechanisms in the offspring, such as the BDNF-TrkB signaling pathway and related factors, while excessive iodine consumption by the mother may exacerbate this effect.

A human-relevant mixture of endocrine disrupting chemicals induces changes in hippocampal DNA methylation correlating with hyperactive behavior in male mice

Humans are ubiquitously exposed to endocrine disrupting chemicals (EDCs), substances that interfere with endogenous hormonal signaling. Exposure during early development is of particular concern due to the programming role of hormones during this period. A previous epidemiological study has shown association between prenatal co-exposure to 8 EDCs (Mixture N1) and language delay in children, suggesting an effect of this mixture on neurodevelopment. Furthermore, in utero exposure to Mixture N1 altered gene expression and behavior in adult mice. In this study, we investigated whether epigenetic mechanisms could underlie the long term effects of Mixture N1 on gene expression and behavior. To this end, we analyzed DNA methylation at regulatory regions of genes whose expression was affected by Mixture N1 in the hippocampus of in utero exposed mice using bisulfite-pyrosequencing. We show that Mixture N1 decreases DNA methylation in males at three genes that are part of the hypothalamus-pituitary-adrenal (HPA) axis: Nr3c1, Nr3c2, and Crhr1, coding for the glucocorticoid receptor, the mineralocorticoid receptor, and the corticotropin releasing hormone receptor 1, respectively. Furthermore, we show that the decrease in Nr3c1 methylation correlates with increased gene expression, and that Nr3c1, Nr3c2, and Crhr1 methylation correlates with hyperactivity and reduction in social behavior. These findings indicate that an EDC mixture corresponding to a human exposure scenario induces epigenetic changes, and thus programming effects, on the HPA axis that are reflected in the behavioral phenotypes of the adult male offspring.

Environmental contaminants, endocrine disruption, and transgender: Can "born that way" in some cases be toxicologically real?

Gender is viewed by many as strictly binary based on a collection of body traits typical of a female or male phenotype, presence of a genotype that includes at least one copy of a Y chromosome, or ability to produce either egg or sperm cells. A growing non-binary view is that these descriptors, while compelling, may nonetheless fail to accurately capture an individual's true gender. The position of the American Psychological Association (APA) agrees with this view and is that transgender people are a defendable and real part of the human population. The considerable diversity of transgender expression then argues against any unitary or simple explanations, however, prenatal hormone levels, genetic influences, and early and later life experiences have been suggested as playing roles in development of transgender identities. The present review considers existing and emerging toxicologic data that may also support an environmental chemical contribution to some transgender identities, and suggest the possibility of a growing nonbinary brain gender continuum in the human population.

SARS-CoV-2 (COVID-19) as a possible risk factor for neurodevelopmental disorders

Pregnant women constitute one of the most vulnerable populations to be affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the cause of coronavirus disease 2019. SARS-CoV-2 infection during pregnancy could negatively impact fetal brain development via multiple mechanisms. Accumulating evidence indicates that mother to fetus transmission of SARS-CoV-2 does occur, albeit rarely. When it does occur, there is a potential for neuroinvasion via immune cells, retrograde axonal transport, and olfactory bulb and lymphatic pathways. In the absence of maternal to fetal transmission, there is still the potential for negative neurodevelopmental outcomes as a consequence of disrupted placental development and function leading to preeclampsia, preterm birth, and intrauterine growth restriction. In addition, maternal immune activation may lead to hypomyelination, microglial activation, white matter damage, and reduced neurogenesis in the developing fetus. Moreover, maternal immune activation can disrupt the maternal or fetal hypothalamic-pituitary-adrenal (HPA) axis leading to altered neurodevelopment. Finally, pro-inflammatory cytokines can potentially alter epigenetic processes within the developing brain. In this review, we address each of these potential mechanisms. We propose that SARS-CoV-2 could lead to neurodevelopmental disorders in a subset of pregnant women and that long-term studies are warranted.

Thyroid hormones: Metabolism and transportation in the fetoplacental unit

The thyroid hormones (THs), thyroxine (T4) and triiodothyronine (T3), are of vital importance for fetal development. The concentration of THs in fetal circulation varies throughout gestation and differs from the concentration in the maternal serum, indicating the presence of maternal-fetal thyroid homeostasis regulatory mechanisms in the placenta. The passage of THs from maternal circulation to fetal circulation is modulated by plasma membrane transporters, enzymes, and carrier proteins. Monocarboxylate transporter 8, iodothyronine deiodinases (DIO2 and DIO3), and transthyretin are especially involved in this maternal-fetal thyroid modulation, shown by a greater expression in the placenta. THs also play a role in placental development and as expected, abnormal variations in TH levels are associated with pregnancy complications and can result in damage to the fetus. Although new evidence regarding TH regulation during pregnancy and its effects in the mother, placenta, and fetus has been published, many aspects of these interactions are still poorly understood. The objective of this review is to provide an evidence-based update, drawn from current data, on the metabolism and transport of THs in the placenta and their vital role in the maternal-fetal relationship.

Association of exposure to ambient particulate matter with maternal thyroid function in early pregnancy

BACKGROUND

It is known that maternal thyroid dysfunction during early pregnancy can cause adverse pregnancy complications and birth outcomes. This study was designed to examine the association between ambient particulate matter with aerodynamic diameters ≤2.5 μm (PM2.5) and particulate matter with aerodynamic diameters ≤10 μm (PM10) exposure and maternal thyroid function during early pregnancy.

METHODS

This study was based on data from a birth cohort study of 921 pregnant women in China. We estimated associations between ambient PM2.5 and PM10 exposure during the first trimester of pregnancy (estimated with land-use regression models) and maternal thyroid hormone concentrations (free thyroxine (FT4), free tri-iodothyronine (FT3), and thyroid-stimulating hormone (TSH)) collected between weeks 10 and 17 of gestation using linear regression models adjusting for potential confounders. Ambient PM2.5 and PM10 concentrations were modeled per interquartile range (IQR) increment and as tertiles based on the distribution of the exposure levels.

RESULTS

An IQR increment (68 μg/m3) in PM2.5 exposure was associated with a significant decrease in maternal FT4 levels (β = -0.60, 95% CI: -1.07, -0.12); and a significant decrease in FT4/FT3 ratio (β = -0.13, 95% CI: -0.25, -0.02). Further analyses showed that, relative to the lowest tertile, women in both the middle and highest tertiles of PM2.5 had significantly lower concentrations of maternal FT4 and FT4/FT3 ratio. No significant associations were found between PM2.5 and FT3 or TSH levels. PM10 exposure was not significantly associated with maternal thyroid function.

CONCLUSIONS

Our study suggested that higher ambient PM2.5, not PM10, exposed during the first trimester of pregnancy were associated with a significant decrease in maternal serum FT4 concentrations and FT4/FT3 ratio. Studies in populations with different exposure levels are needed to replicate our study results.

Retrospective analysis and literature review of four cases of thyroid hormone resistance syndrome caused by THRB gene mutation

BACKGROUND

To summarize the clinical characteristics, genetics and follow-up data of four children with thyroid hormone resistance (RTH) syndrome and review the related literatures.

METHODS

The clinical data of the four children diagnosed with RTH syndrome in our hospital from 2018 to 2020 were retrospectively analyzed. Next-generation sequencing of the candidate genes related to thyroid diseases was performed using the blood collected from all the children and their parents who signed an informed consent. Then, relevant cases were retrieved on medical literature databases for analysis and summary.

RESULTS

Among the four cases, three cases of goiter; two cases of tachycardia, palpitations, personality change, hyperactivity, weight loss; one case of academic performance decline, and no hearing and vision loss were observed. Laboratory thyroid function tests indicated a mild increase in free triiodothyronine and with or without increased free thyroxine levels. Thyroid-stimulating hormone (TSH) levels were normal or slightly elevated, but thyrotropin receptor autoantibodies were negative. Octreotide inhibition test showed that the TSH levels of all the children decreased by more than 50% compared with the basal value (the genes of four cases were positive). However, magnetic resonance imaging of the pituitary gland showed no abnormalities. Related gene detection in the children and their families showed that four cases had THRB mutations: two proband mutations were from their fathers, and two cases had de novo mutations.

CONCLUSIONS

The clinical manifestations of pediatric RTH syndrome vary, and the diagnosis mainly depends on thyroid function tests. Heterozygous mutations in THRB are overall rare, even if with the advanced development of next-generation sequencing, not all the children with RTH syndrome have mutations. Furthermore, octreotide inhibition tests cannot be used as a diagnostic criterion to distinguish RTH syndrome from pituitary tumors in children.

Maternal Obesity and Gut Microbiota Are Associated with Fetal Brain Development

Obesity in pregnancy induces metabolic syndrome, low-grade inflammation, altered endocrine factors, placental function, and the maternal gut microbiome. All these factors impact fetal growth and development, including brain development. The lipid metabolic transporters of the maternal-fetal-placental unit are dysregulated in obesity. Consequently, the transport of essential long-chain PUFAs for fetal brain development is disturbed. The mother’s gut microbiota is vital in maintaining postnatal energy homeostasis and maternal-fetal immune competence. Obesity during pregnancy changes the gut microbiota, affecting fetal brain development. Obesity in pregnancy can induce placental and intrauterine inflammation and thus influence the neurodevelopmental outcomes of the offspring. Several epidemiological studies observed an association between maternal obesity and adverse neurodevelopment. This review discusses the effects of maternal obesity and gut microbiota on fetal neurodevelopment outcomes. In addition, the possible mechanisms of the impacts of obesity and gut microbiota on fetal brain development are discussed.

Filtered air intervention modulates hypothalamic-pituitary-thyroid/gonadal axes by attenuating inflammatory responses in adult rats after fine particulate matter (PM2.5) exposure

We have previously reported that filtered air (FA) intervention reduces inflammation and hypothalamus-pituitary-adrenal axis activation after fine particulate matter (PM2.5 exposure). Whether FA also modulates the hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-gonadal (HPG) axes in rats after PM2.5 exposure is still unknown. Adult Sprague-Dawley rats were exposed to PM2.5 by using a "real-world" PM2.5 exposure system, and the FA intervention was conducted by renewing for 15 days. PM2.5 inhalation decreased thyrotropin-releasing hormone (TRH) and thyroxine (T4) levels in both male and female rats, and thyroid-stimulating hormone (TSH) level in male rats. FA intervention attenuated the reduction in TRH and TSH levels in male rats and reduction in T4 level in female rats. PM2.5 inhalation also reduced testosterone (T) level in male rats, and estradiol (E2) and progesterone (PROG) levels in female rats, and these changes were attenuated after FA intervention. The FA intervention attenuated the decreases in CD8 T cells and T cells induced by PM2.5 inhalation in female rats only by flow cytometry analysis. In blood, FA interventions ameliorated IL-6 and IL-1β mRNA levels in both male and female rats after PM2.5 exposure. FA intervention restored the IL-4 and IL-10 levels in female rats after PM2.5 exposure. Moreover, FA intervention ameliorated the inflammatory responses induced by PM2.5 inhalation in the thyroid and gonads in both male and female rats. These data indicate that FA intervention exerted an effect on modulating the hormonal balance of the HPT and HPG axes, and this may be related to a reduction in the inflammatory responses in the thyroid and gonads of PM2.5-treated rats, respectively.

Neurodegenerative Diseases: Implications of Environmental and Climatic Influences on Neurotransmitters and Neuronal Hormones Activities

Neurodegenerative and neuronal-related diseases are major public health concerns. Human vulnerability to neurodegenerative diseases (NDDs) increases with age. Neuronal hormones and neurotransmitters are major determinant factors regulating brain structure and functions. The implications of environmental and climatic changes emerged recently as influence factors on numerous diseases. However, the complex interaction of neurotransmitters and neuronal hormones and their depletion under environmental and climatic influences on NDDs are not well established in the literature. In this review, we aim to explore the connection between the environmental and climatic factors to NDDs and to highlight the available and potential therapeutic interventions that could use to improve the quality of life and reduce susceptibility to NDDs.

Triphenyl phosphate disturbs placental tryptophan metabolism and induces neurobehavior abnormal in male offspring

Epidemiological studies have shown that prenatal triphenyl phosphate (TPhP) exposure is related to abnormal neurobehavior in children. However, the neurodevelopmental toxicity of TPhP in mammals is limited. To study the neurodevelopmental toxicity of TPhP in mammals and investigate the underlying mechanism, we used a mouse intrauterine TPhP exposure model. We measured the inflammatory factors (IL-6, TNFα) and NFκB levels, and tryptophan metabolism in placentae, detected the fetal brain transcriptome, hippocampal neuron development and neurobehavioral in the male offspring. The results showed that the protein level of IL-6, TNFα and NFκB in the placenta of the TPhP treatment group (1, 5 mg/kg) were significantly increased. Change of the protein level of these pro-inflammatory factors in maternal serum or fetal brain was not observed. Expression of genes along tryptophan-serotonin metabolism pathway were significantly decreased. While, the concentration of 5-HT levels in the placenta or fetal brain were significantly increased. Consistent with the increased 5-HT, the Nissl body was reduced in the hippocampus of treatment group. The expression of serotonergic neuron gene markers including Tph2, Htr1A, Htr2A, Pet1 and Lmx1b in the hippocampus of treatment group was significantly decreased. The neurobehavioral test showed that TPhP decreased center time that represent anxiety-like behavior, and reduced learning and memory in male offspring. Meanwhile, expression of genes along tryptophan-kynurenine metabolism pathway were significantly increased. The result of the transcriptome analysis of fetal brain showed that the differentially expressed genes are mainly involved in the transcription regulation of DNA as a template in the nucleus, and the enriched pathways are mainly signal pathways regulated by axon guidance and neurotrophic factors, dopaminergic and cholinergic synapses, suggest that not only serotonergic neuronal was affected. Overall, this study demonstrates that TPhP has the potential to induce placental inflammatory response in the placenta, disturb placental tryptophan metabolism, compromise the neuronal development and synaptic transmission, and cause abnormal neurobehavior in male offspring.

Iodine Status Modifies the Association between Fluoride Exposure in Pregnancy and Preschool Boys' Intelligence

In animal studies, the combination of in utero fluoride exposure and low iodine has greater negative effects on offspring learning and memory than either alone, but this has not been studied in children. We evaluated whether the maternal urinary iodine concentration (MUIC) modifies the association between maternal urinary fluoride (MUF) and boys' and girls' intelligence. We used data from 366 mother-child dyads in the Maternal-Infant Research on Environmental Chemicals Study. We corrected trimester-specific MUF and MUIC for creatinine, and averaged them to yield our exposure variables (MUFCRE, mg/g; MUICCRE, µg/g). We assessed children's full-scale intelligence (FSIQ) at 3 to 4 years. Using multiple linear regression, we estimated a three-way interaction between MUFCRE, MUICCRE, and child sex on FSIQ, controlling for covariates. The MUICCRE by MUFCRE interaction was significant for boys (p = 0.042), but not girls (p = 0.190). For boys whose mothers had low iodine, a 0.5 mg/g increase in MUFCRE was associated with a 4.65-point lower FSIQ score (95% CI: -7.67, -1.62). For boys whose mothers had adequate iodine, a 0.5 mg/g increase in MUFCRE was associated with a 2.95-point lower FSIQ score (95% CI: -4.77, -1.13). These results suggest adequate iodine intake during pregnancy may minimize fluoride's neurotoxicity in boys.

Maternal exposure to atmospheric PM2.5 and fetal brain development: Associations with BAI1 methylation and thyroid hormones

Maternal exposure to atmospheric fine particulate matter (PM_2.5) during pregnancy is associated with adverse fetal development, including abnormal brain development. However, the underlying mechanisms and influencing factors remain uncertain. This study investigated the roles of DNA methylation in genes involving neurodevelopment and thyroid hormones (THs) in fetal brain development after maternal exposure to PM_2.5 from e-waste. Among 939 healthy pregnant women recruited from June 2011 to September 2012, 101 e-waste-exposed and 103 reference mother-infant pairs (204 pairs totally) were included. Annual ground-level PM_2.5 concentrations over e-waste-exposed area (116.38°E, 23.29°N) and reference area (116.67°E, 23.34°N) in 2011, 2012 were obtained by estimates and maternal exposure was evaluated by calculating individual chronic daily intakes (CDIs) of PM_2.5. Methylation and THs including thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) level were measured in umbilical cord blood collected shortly after delivery. We found higher ground-level PM_2.5 concentrations led to greater individual CDI of PM_2.5 in e-waste-exposed pregnant women. After adjustment for gender and birth BMI, significant mediation effects on the adverse associations of maternal PM_2.5 exposure with birth head circumference were observed for methylations at positions +13 and + 32 (respectively mediated proportion of 9.8% and 5.3%, P < 0.05 and P < 0.01) in the brain-specific angiogenesis inhibitor 1 (BAI1) gene, but not for methylations in the catenin cadherin-associated protein, alpha 2 (CTNNA2) gene. BAI1 (position +13) methylation was also significantly correlated with FT3 levels (r_s = -0.156, P = 0.032), although maternal CDI of PM_2.5 was positively associated with higher odds of abnormal TSH levels (OR = 5.03, 95% CI: 1.00, 25.20, P = 0.05) rather than FT3 levels. Our findings suggest that methylation (likely linked to THs) in neonates may play mediation roles associated with abnormal brain development risk due to maternal exposure to atmospheric PM_2.5 from e-waste.

The importance of nutrition in pregnancy and lactation: lifelong consequences

Most women in the United States do not meet the recommendations for healthful nutrition and weight before and during pregnancy. Women and providers often ask what a healthy diet for a pregnant woman should look like. The message should be “eat better, not more.” This can be achieved by basing diet on a variety of nutrient-dense, whole foods, including fruits, vegetables, legumes, whole grains, healthy fats with omega-3 fatty acids that include nuts and seeds, and fish, in place of poorer quality highly processed foods. Such a diet embodies nutritional density and is less likely to be accompanied by excessive energy intake than the standard American diet consisting of increased intakes of processed foods, fatty red meat, and sweetened foods and beverages. Women who report “prudent” or “health-conscious” eating patterns before and/or during pregnancy may have fewer pregnancy complications and adverse child health outcomes. Comprehensive nutritional supplementation (multiple micronutrients plus balanced protein energy) among women with inadequate nutrition has been associated with improved birth outcomes, including decreased rates of low birthweight. A diet that severely restricts any macronutrient class should be avoided, specifically the ketogenic diet that lacks carbohydrates, the Paleo diet because of dairy restriction, and any diet characterized by excess saturated fats. User-friendly tools to facilitate a quick evaluation of dietary patterns with clear guidance on how to address dietary inadequacies and embedded support from trained healthcare providers are urgently needed.

Recent evidence has shown that although excessive gestational weight gain predicts adverse perinatal outcomes among women with normal weight, the degree of prepregnancy obesity predicts adverse perinatal outcomes to a greater degree than gestational weight gain among women with obesity. Furthermore, low body mass index and insufficient gestational weight gain are associated with poor perinatal outcomes. Observational data have shown that first-trimester gain is the strongest predictor of adverse outcomes. Interventions beginning in early pregnancy or preconception are needed to prevent downstream complications for mothers and their children. For neonates, human milk provides personalized nutrition and is associated with short- and long-term health benefits for infants and mothers. Eating a healthy diet is a way for lactating mothers to support optimal health for themselves and their infants.

A global timing mechanism regulates cell-type-specific wiring programmes

The assembly of neural circuits is dependent on precise spatiotemporal expression of cell recognition molecules^1-5. Factors controlling cell type specificity have been identified^6-8, but how timing is determined remains unknown. Here we describe induction of a cascade of transcription factors by a steroid hormone (ecdysone) in all fly visual system neurons spanning target recognition and synaptogenesis. We demonstrate through single-cell sequencing that the ecdysone pathway regulates the expression of a common set of targets required for synaptic maturation and cell-type-specific targets enriched for cell-surface proteins regulating wiring specificity. Transcription factors in the cascade regulate the expression of the same wiring genes in complex ways, including activation in one cell type and repression in another. We show that disruption of the ecdysone pathway generates specific defects in dendritic and axonal processes and synaptic connectivity, with the order of transcription factor expression correlating with sequential steps in wiring. We also identify shared targets of a cell-type-specific transcription factor and the ecdysone pathway that regulate specificity. We propose that neurons integrate a global temporal transcriptional module with cell-type-specific transcription factors to generate different cell-type-specific patterns of cell recognition molecules regulating wiring.

Circadian rhythms of locomotor activity in rats: Data on the effect of morphine administered from the early stages of embryonic development until weaning

The circadian clock generates behavioural and physiological rhythms to maximize the efficacy of organismal functions. The circadian system with a major circadian pacemaker in the suprachiasmatic nucleus of the hypothalamus develops gradually and its proper function in adulthood depends on an appropriate neurochemical milieu during ontogeny [1]. Locomotor activity is under direct control by the circadian clock, and alterations in its rhythmicity indicate changes of circadian clock function. We evaluated circadian parameters of locomotor rhythms of adult male Wistar rats born to mothers that were exposed to a stable dose of 0.1 mg/ml of morphine in drinking water (36 ml water on average/day/each rat) from embryonic day 10 (E10) until weaning at postnatal day 28 (P28). Increasing the dose of morphine in drinking water was used to evaluate the changes in the rhythmic gene expression in the suprachiasmatic nucleus and in the livers of young rats at P20 [2]. At P90, we started measurement of endogenous rhythmicity for 12 days in constant darkness (DD), then we applied a 15 min light pulse at circadian time 15 (CT15) and followed the animals for the next 15 days in DD. We evaluated the magnitude of light-induced phase shift and compared the circadian parameters of free-running rhythmicity in the intervals before and after the light pulse. All data were also compared between morphine-exposed animals (M group) and controls (C group) that were not exposed to morphine. An unpaired t-test confirmed a significantly longer light-induced phase delay in M group compared with C group, a prolonged circadian period in M group in the interval after the light pulse, and greater amplitude for C group in the first interval, i.e. before the light pulse. No change in total activity counts between groups was confirmed.