Convergence of Sex Differences and the Neuroimmune System in Autism Spectrum Disorder

The Search for the Causes of Common Hyperandrogenism, 1965 to Circa 2015

From 1965 to 2015, immense strides were made into understanding the mechanisms underlying the common androgen excess disorders, premature adrenarche and polycystic ovary syndrome (PCOS). The author reviews the critical discoveries of this era from his perspective investigating these disorders, commencing with his early discoveries of the unique pattern of plasma androgens in premature adrenarche and the elevation of an index of the plasma free testosterone concentration in most hirsute women. The molecular genetic basis, though not the developmental biologic basis, for adrenarche is now known and 11-oxytestosterones shown to be major bioactive adrenal androgens. The evolution of the lines of research into the pathogenesis of PCOS is historically traced: research milestones are cited in the areas of neuroendocrinology, insulin resistance, hyperinsulinism, type 2 diabetes mellitus, folliculogenesis, androgen secretion, obesity, phenotyping, prenatal androgenization, epigenetics, and complex genetics. Large-scale genome-wide association studies led to the 2014 discovery of an unsuspected steroidogenic regulator DENND1A (differentially expressed in normal and neoplastic development). The splice variant DENND1A.V2 is constitutively overexpressed in PCOS theca cells in long-term culture and accounts for their PCOS-like phenotype. The genetics are complex, however: DENND1A intronic variant copy number is related to phenotype severity, and recent data indicate that rare variants in a DENND1A regulatory network and other genes are related to PCOS. Obesity exacerbates PCOS manifestations via insulin resistance and proinflammatory cytokine excess; excess adipose tissue also forms testosterone. Polycystic ovaries in 40 percent of apparently normal women lie on the PCOS functional spectrum. Much remains to be learned.

Sex-Differential Gene Expression in Developing Human Cortex and Its Intersection With Autism Risk Pathways

Background

Sex-differential biology may contribute to the consistently male-biased prevalence of autism spectrum disorder (ASD). Gene expression differences between males and females in the brain can indicate possible molecular and cellular mechanisms involved, although transcriptomic sex differences during human prenatal cortical development have been incompletely characterized, primarily due to small sample sizes.

Methods

We performed a meta-analysis of sex-differential expression and co-expression network analysis in 2 independent bulk RNA sequencing datasets generated from cortex of 273 prenatal donors without known neuropsychiatric disorders. To assess the intersection between neurotypical sex differences and neuropsychiatric disorder biology, we tested for enrichment of ASD-associated risk genes and expression changes, neuropsychiatric disorder risk genes, and cell type markers within identified sex-differentially expressed genes (sex-DEGs) and sex-differential co-expression modules.

Results

We identified 101 significant sex-DEGs, including Y-chromosome genes, genes impacted by X-chromosome inactivation, and autosomal genes. Known ASD risk genes, implicated by either common or rare variants, did not preferentially overlap with sex-DEGs. We identified 1 male-specific co-expression module enriched for immune signaling that is unique to 1 input dataset.

Conclusions

Sex-differential gene expression is limited in prenatal human cortex tissue, although meta-analysis of large datasets allows for the identification of sex-DEGs, including autosomal genes that encode proteins involved in neural development. Lack of sex-DEG overlap with ASD risk genes in the prenatal cortex suggests that sex-differential modulation of ASD symptoms may occur in other brain regions, at other developmental stages, or in specific cell types, or may involve mechanisms that act downstream from mutation-carrying genes.

Gestational hypothyroxinemia induces ASD-like phenotypes in behavior, proinflammatory markers, and glutamatergic protein expression in mouse offspring of both sexes

Background

The prevalence of autism spectrum disorder (ASD) has significantly risen in the past three decades, prompting researchers to explore the potential contributions of environmental factors during pregnancy to ASD development. One such factor of interest is gestational hypothyroxinemia (HTX), a frequent condition in pregnancy associated with cognitive impairments in the offspring. While retrospective human studies have linked gestational HTX to autistic traits, the cellular and molecular mechanisms underlying the development of ASD-like phenotypes remain poorly understood. This study used a mouse model of gestational HTX to evaluate ASD-like phenotypes in the offspring.

Methods

To induce gestational HTX, pregnant mice were treated with 2-mercapto-1-methylimidazole (MMI), a thyroid hormones synthesis inhibitor, in the tap-drinking water from embryonic days (E) 10 to E14. A separate group received MMI along with a daily subcutaneous injection of T4, while the control group received regular tap water during the entire pregnancy. Female and male offspring underwent assessments for repetitive, anxious, and social behaviors from postnatal day (P) 55 to P64. On P65, mice were euthanized for the evaluation of ASD-related inflammatory markers in blood, spleen, and specific brain regions. Additionally, the expression of glutamatergic proteins (NLGN3 and HOMER1) was analyzed in the prefrontal cortex and hippocampus.

Results

The HTX-offspring exhibited anxious-like behavior, a subordinate state, and impaired social interactions. Subsequently, both female and male HTX-offspring displayed elevated proinflammatory cytokines in blood, including IL-1β, IL-6, IL-17A, and TNF-α, while only males showed reduced levels of IL-10. The spleen of HTX-offspring of both sexes showed increased Th17/Treg ratio and M1-like macrophages. In the prefrontal cortex and hippocampus of male HTX-offspring, elevated levels of IL-17A and reduced IL-10 were observed, accompanied by increased expression of hippocampal NLGN3 and HOMER1. All these observations were compared to those observed in the Control-offspring. Notably, the supplementation with T4 during the MMI treatment prevents the development of the observed phenotypes. Correlation analysis revealed an association between maternal T4 levels and specific ASD-like outcomes.

Discussion

This study validates human observations, demonstrating for the first time that gestational HTX induces ASD-like phenotypes in the offspring, highlighting the need of monitoring thyroid function during pregnancy.

Role of estrogen in sex differences in memory, emotion and neuropsychiatric disorders

Estrogen regulates a wide range of neuronal functions in the brain, such as dendritic spine formation, remodeling of synaptic plasticity, cognition, neurotransmission, and neurodevelopment. Estrogen interacts with intracellular estrogen receptors (ERs) and membrane-bound ERs to produce its effect via genomic and non-genomic pathways. Any alterations in these pathways affect the number, size, and shape of dendritic spines in neurons associated with psychiatric diseases. Increasing evidence suggests that estrogen fluctuation causes changes in dendritic spine density, morphology, and synapse numbers of excitatory and inhibitory neurons differently in males and females. In this review, we discuss the role of estrogen hormone in rodents and humans based on sex differences. First, we explain estrogen role in learning and memory and show that a high estrogen level alleviates the deficits in learning and memory. Secondly, we point out that estrogen produces a striking difference in emotional memories in men and women, which leads them to display sex-specific differences in underlying neuronal signaling. Lastly, we discuss that fluctuations in estrogen levels in men and women are related to neuropsychiatric disorders, including schizophrenia, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), bipolar disorder (BPD), major depressive disorder (MDD), substance use disorder (SUD), and anxiety disorders.

Acetaminophen causes neurodevelopmental injury in susceptible babies and children: no valid rationale for controversy

Despite the worldwide acceptance of acetaminophen (APAP) as a necessary medicine in pediatrics, evidence that early exposure to APAP causes neurodevelopmental injury in susceptible babies and children has been mounting for over a decade. The evidence is diverse and includes extensive work with laboratory animals, otherwise unexplained associations, factors associated with APAP metabolism, and limited studies in humans. Although the evidence has reached an overwhelming level and was recently reviewed in detail, controversy persists. This narrative review evaluates some of that controversy. Evidence from the pre- and postpartum periods was considered to avoid controversy raised by consideration of only limited evidence of risks during the prepartum period. Among other issues, the association between APAP use and the prevalence of neurodevelopmental disorders was considered. A systematic review revealed that the use of APAP in the pediatric population was never tracked carefully; however, historical events that affected its use were documented and are sufficient to establish apparent correlations with changes in the prevalence of neurodevelopmental disorders. Moreover, problems with the exclusive reliance on results of meta-analyses of large datasets with limited time frames of drug exposure were reviewed. Furthermore, the evidence of why some children are susceptible to APAPinduced neurodevelopmental injuries was examined. We concluded that available evidence demonstrates that early exposure to APAP causes neurodevelopmental injury in susceptible babies and small children.

Mutations associated with autism lead to similar synaptic and behavioral alterations in both sexes of male and female mouse brain

Autism spectrum disorder (ASD) is a neurodevelopmental disorder based on synaptic abnormalities. The estimated prevalence rate of male individuals diagnosed with ASD prevails over females is in a proportion of 4:1. Consequently, males remain the main focus in ASD studies in clinical and experimental settings. Meanwhile, some studies point to an underestimation of this disorder in females. In this work, we studied the sex differences of the synaptic and behavioral phenotypes of ASD mouse models. Juvenile male and female Shank3Δ4-22 and Cntnap2-/- mutant mice and their WT littermates were used in the experiments. The animals were subjected to a Three-Chamber Sociability Test, then euthanized, and the whole cortex was used for the evaluation of the synaptic phenotype. Protein levels of glutamatergic (NR1) and GABAergic (GAD1 and VGAT) neuronal markers were measured. Protein level of synaptophysin (Syp) was also measured. Dendritic spine density in somatosensory neurons was analyzed by Golgi staining methods. Spine Density and GAD1, NR1, VGAT, and Syp levels were significantly reduced in Shank3Δ4-22 and Cntnap2-/- mice compared to the control group irrespective of sex, indicating impaired synaptic development in the mutant mice. These results were consistent with the lack of differences in the three-chamber sociability test between male and female mice. In conclusion, female ASD mice of both mutations undergo similar synaptic aberrations as their male counterparts and need to be studied along with the male animals. Finally, this work urges the psychiatry scientific community to use both sexes in their investigations.

PLASTAMINATION: Outcomes on the Central Nervous System and Reproduction

BACKGROUND

Environmental exposures to non-biodegradable and biodegradable plastics are unavoidable. Microplastics (MPs) and nanoplastics (NPs) from the manufacturing of plastics (primary sources) and the degradation of plastic waste (secondary sources) can enter the food chain directly or indirectly and, passing biological barriers, could target both the brain and the gonads. Hence, the worldwide diffusion of environmental plastic contamination (PLASTAMINATION) in daily life may represent a possible and potentially serious risk to human health.

OBJECTIVE

This review provides an overview of the effects of non-biodegradable and the more recently introduced biodegradable MPs and NPs on the brain and brain-dependent reproductive functions, summarizing the molecular mechanisms and outcomes on nervous and reproductive organs. Data from in vitro, ex vivo, non-mammalian and mammalian animal models and epidemiological studies have been reviewed and discussed.

RESULTS

MPs and NPs from non-biodegradable plastics affect organs, tissues and cells from sensitive systems such as the brain and reproductive organs. Both MPs and NPs induce oxidative stress, chronic inflammation, energy metabolism disorders, mitochondrial dysfunction and cytotoxicity, which in turn are responsible for neuroinflammation, dysregulation of synaptic functions, metabolic dysbiosis, poor gamete quality, and neuronal and reproductive toxicity. In spite of this mechanistic knowledge gained from studies of non-biodegradable plastics, relatively little is known about the adverse effects or molecular mechanisms of MPs and NPs from biodegradable plastics.

CONCLUSION

The neurological and reproductive health risks of MPs/NPs exposure warrant serious consideration, and further studies on biodegradable plastics are recommended.

Gonadal hormones impart male-biased behavioral vulnerabilities to immune activation via microglial mitochondrial function

There is a strong male bias in the prevalence of many neurodevelopmental disorders such as autism spectrum disorder. However, the mechanisms underlying this sex bias remain elusive. Infection during the perinatal period is associated with an increased risk of neurodevelopmental disorder development. Here, we used a mouse model of early-life immune activation that reliably induces deficits in social behaviors only in males. We demonstrate that male-biased alterations in social behavior are dependent upon microglial immune signaling and are coupled to alterations in mitochondrial morphology, gene expression, and function specifically within microglia, the innate immune cells of the brain. Additionally, we show that this behavioral and microglial mitochondrial vulnerability to early-life immune activation is programmed by the male-typical perinatal gonadal hormone surge. These findings demonstrate that social behavior in males over the lifespan are regulated by microglia-specific mechanisms that are shaped by events that occur in early development.

The Dangers of Acetaminophen for Neurodevelopment Outweigh Scant Evidence for Long-Term Benefits

Based on available data that include approximately 20 lines of evidence from studies in laboratory animal models, observations in humans, correlations in time, and pharmacological/toxicological considerations, it has been concluded without reasonable doubt and with no evidence to the contrary that exposure of susceptible babies and children to acetaminophen (paracetamol) induces many, if not most, cases of autism spectrum disorder (ASD). However, the relative number of cases of ASD that might be induced by acetaminophen has not yet been estimated. Here, we examine a variety of evidence, including the acetaminophen-induced reduction of social awareness in adults, the prevalence of ASD through time, and crude estimates of the relative number of ASD cases induced by acetaminophen during various periods of neurodevelopment. We conclude that the very early postpartum period poses the greatest risk for acetaminophen-induced ASD, and that nearly ubiquitous use of acetaminophen during early development could conceivably be responsible for the induction in the vast majority, perhaps 90% or more, of all cases of ASD. Despite over a decade of accumulating evidence that acetaminophen is harmful for neurodevelopment, numerous studies demonstrate that acetaminophen is frequently administered to children in excess of currently approved amounts and under conditions in which it provides no benefit. Further, studies have failed to demonstrate long-term benefits of acetaminophen for the pediatric population, leaving no valid rationale for continued use of the drug in that population given its risks to neurodevelopment.

What risk factors for Developmental Language Disorder can tell us about the neurobiological mechanisms of language development

Language is a complex multidimensional cognitive system that is connected to many neurocognitive capacities. The development of language is therefore strongly intertwined with the development of these capacities and their neurobiological substrates. Consequently, language problems, for example those of children with Developmental Language Disorder (DLD), are explained by a variety of etiological pathways and each of these pathways will be associated with specific risk factors. In this review, we attempt to link previously described factors that may interfere with language development to putative underlying neurobiological mechanisms of language development, hoping to uncover openings for future therapeutical approaches or interventions that can help children to optimally develop their language skills.

Artificial intelligence and bioinformatics analyze markers of children's transcriptional genome to predict autism spectrum disorder

Introduction

Autism spectrum disorder (ASD), characterized by difficulties in social interaction and communication as well as restricted interests and repetitive behaviors, is extremely challenging to diagnose in toddlers. Early diagnosis and intervention are crucial however.

Methods

In this study, we developed a machine learning classification model based on mRNA expression data from the peripheral blood of 128 toddlers with ASD and 126 controls. Differentially expressed genes (DEGs) between ASD and controls were identified.

Results

We identified genes such as UBE4B, SPATA2 and RBM3 as DEGs, mainly involved in immune-related pathways. 21 genes were screened as key biomarkers using LASSO regression, yielding an accuracy of 86%. A neural network model based on these 21 genes achieved an AUC of 0.88.

Discussion

Our findings suggest that the identified neurotransmitters and 21 immune-related biomarkers may facilitate the early diagnosis of ASD. The mRNA expression profile sheds light on the biological underpinnings of ASD in toddlers and potential biomarkers for early identification. Nevertheless, larger samples are needed to validate these biomarkers.

Maternal high-fat diet alters the neurobehavioral, biochemical and inflammatory parameters of their adult female rat offspring

BACKGROUND

Lipid metabolism dysregulations have been associated with depressive and anxious behaviors which can affect pregnant and lactating individuals, with indications that such changes extend to the offspring. Therefore, the aim of this study was to evaluate the effect of a maternal high-fat diet on the neurobehavioral, biochemical and inflammatory parameters of their adult female offspring.

METHODS

Wistar rats ± 90 days old were mated. The dams were allocated to consume a control (CTL) or high-fat (HFD) diet during pregnancy and lactation. After weaning, the female offspring from the CTL (N=10) and HFD (N=10) groups received standard chow. The offspring behavioral tests were started at 120 days old. Then, the somatic measures were evaluated followed by euthanasia, histological and biochemical analyses.

RESULTS

The HFD group had less ambulation and longer immobility time in the open field test compared to the CTL. The HFD group had lower HDL (48.4%) and a higher adiposity (71.8%) and LDL (62.2%) than the CTL. The CTL had a higher organic acid concentration in the intestine, mainly acetic and butyric acids, however the HFD had a higher citric and acetic acid concentration in the brain and ischemic lesion in the hippocampus with a higher NF-κB concentration.

CONCLUSION

The results demonstrate deleterious effects of a maternal HFD on the neurobehavioral and biochemical parameters of their offspring which may be associated with the role of organic acids and NF-κB in fetal programming.

Do Savant Syndrome and Autism Spectrum Disorders Share Sex Differences? A Comprehensive Review

Savant syndrome was described before autism. However, they soon became closely associated, as many of their symptoms (intellectual disability, repetitive behaviors, alterations in social communication, and islets of abilities) overlap. Only a few women with autism have been diagnosed with savant syndrome. The theories or hypotheses that attempt to explain savant syndrome, which are common in autism, present differential treatment according to sex. We postulate that savant syndrome associated with autism as well as autism in general is underdiagnosed in women.

Sex and gender in neurodevelopmental conditions

Health-related conditions often differ qualitatively or quantitatively between individuals of different birth-assigned sexes and gender identities, and/or with different gendered experiences, requiring tailored care. Studying the moderating and mediating effects of sex-related and gender-related factors on impairment, disability, wellbeing and health is of paramount importance especially for neurodivergent individuals, who are diagnosed with neurodevelopmental conditions with uneven sex/gender distributions. Researchers have become aware of the myriad influences that sex-related and gender-related variables have on the manifestations of neurodevelopmental conditions, and contemporary work has begun to investigate the mechanisms through which these effects are mediated. Here we describe topical concepts of sex and gender science, summarize current knowledge, and discuss research and clinical challenges related to autism, attention-deficit/hyperactivity disorder and other neurodevelopmental conditions. We consider sex and gender in the context of epidemiology, behavioural phenotypes, neurobiology, genetics, endocrinology and neighbouring disciplines. The available evidence supports the view that sex and gender are important contributors to the biological and behavioural variability in neurodevelopmental conditions. Methodological caveats such as frequent conflation of sex and gender constructs, inappropriate measurement of these constructs and under-representation of specific demographic groups (for example, female and gender minority individuals and people with intellectual disabilities) limit the translational potential of research so far. Future research and clinical implementation should integrate sex and gender into next-generation diagnostics, mechanistic investigations and support practices.

Steroid hormone pathways, vitamin D and autism: a systematic review

The origins of the male preponderance in autism incidence remain unclear. The idea that perinatal factors associated with sex differentiation (e.g., steroid hormone pathways) may increase the possibility of the emergence of autism is complementary to the hypothesis that female individuals are intrinsically less likely to develop autism. Empirical evidence for the mechanistic roles of in utero steroid hormones in autism etiology is accumulating but inconsistent. We conducted a systematic review using rigorous criteria for the measurements of steroids and vitamin D exposure, to summarize the potential contributing roles of prenatal and early postnatal steroids and vitamin D alterations to the emergence of autism. We searched PubMed, PsychInfo, Scopus, and included 22 studies for qualitative synthesis. Among them, six studies examined the association of autism diagnoses in offspring and levels of steroids and precursor steroid hormones in the fetal environment, eight studies examined the associations between autism and maternal and fetal blood vitamin D levels during pregnancy and at birth, and eight studies examined the associations between offspring autism diagnoses and maternal hyperandrogenemia diagnosed before pregnancy. We identified promising and complex results regarding the relations between steroid metabolism and autism. The interpretation of findings was limited by the mostly observational study designs, insufficient investigation of the effects of offspring sex, confounders and their cumulative effects on the development of the child, and unclear impact of the timing of steroids exposure and their effects on fetal neurodevelopment.

Sex-Related Changes in the Clinical, Genetic, Electrophysiological, Connectivity, and Molecular Presentations of ASD: A Comparison between Human and Animal Models of ASD with Reference to Our Data

The etiology of autism spectrum disorder (ASD) is genetic, environmental, and epigenetic. In addition to sex differences in the prevalence of ASD, which is 3-4 times more common in males, there are also distinct clinical, molecular, electrophysiological, and pathophysiological differences between sexes. In human, males with ASD have more externalizing problems (i.e., attention-deficit hyperactivity disorder), more severe communication and social problems, as well as repetitive movements. Females with ASD generally exhibit fewer severe communication problems, less repetitive and stereotyped behavior, but more internalizing problems, such as depression and anxiety. Females need a higher load of genetic changes related to ASD compared to males. There are also sex differences in brain structure, connectivity, and electrophysiology. Genetic or non-genetic experimental animal models of ASD-like behavior, when studied for sex differences, showed some neurobehavioral and electrophysiological differences between male and female animals depending on the specific model. We previously carried out studies on behavioral and molecular differences between male and female mice treated with valproic acid, either prenatally or early postnatally, that exhibited ASD-like behavior and found distinct differences between the sexes, the female mice performing better on tests measuring social interaction and undergoing changes in the expression of more genes in the brain compared to males. Interestingly, co-administration of S-adenosylmethionine alleviated the ASD-like behavioral symptoms and the gene-expression changes to the same extent in both sexes. The mechanisms underlying the sex differences are not yet fully understood.

Autism in Women

Relative to males, women with autism spectrum disorder (ASD) have neurobiological and clinical presentation differences. Recent research suggests that the male/female ASD prevalence gap is smaller than previously reported. Sex differences in symptom presentation as well as the male bias of ASD account for delayed/missed diagnosis among women. Investigating ASD and providing psychological evaluation referrals for women who are struggling socially and present with complex mental health conditions (e.g., ADHD, depression), even when they do not show typical autistic characteristics, is important. Accurate diagnosis facilitates understanding of challenges, increases access to treatments, and alleviates the burden of ASD.

Advancing research on early autism through an integrated risk and resilience perspective

To date, a deficit-oriented approach dominates autism spectrum disorder (ASD) research, including studies of infant siblings of children with ASD at high risk (HR) for the disabilities associated with this disorder. Despite scientific advances regarding early ASD-related risk, there remains little systematic investigation of positive development, limiting the scope of research and quite possibly a deeper understanding of pathways toward and away from ASD-related impairments. In this paper, we argue that integrating a resilience framework into early ASD research has the potential to enhance knowledge on prodromal course, phenotypic heterogeneity, and developmental processes of risk and adaptation. We delineate a developmental systems resilience framework with particular reference to HR infants. To illustrate the utility of a resilience perspective, we consider the "female protective effect" and other evidence of adaptation in the face of ASD-related risk. We suggest that a resilience framework invites focal questions about the nature, timing, levels, interactions, and mechanisms by which positive adaptation occurs in relation to risk and developmental pathways toward and away from ASD-related difficulties. We conclude with recommendations for future research, including more focus on adaptive development and multisystem processes, pathways away from disorder, and reconsideration of extant evidence within an integrated risk-and-resilience framework.

The Link Between Autism and Sex-Related Neuroanatomy, and Associated Cognition and Gene Expression

OBJECTIVE

The male preponderance in prevalence of autism is among the most pronounced sex ratios across neurodevelopmental conditions. The authors sought to elucidate the relationship between autism and typical sex-differential neuroanatomy, cognition, and related gene expression.

METHODS

Using a novel deep learning framework trained to predict biological sex based on T₁-weighted structural brain images, the authors compared sex prediction model performance across neurotypical and autistic males and females. Multiple large-scale data sets comprising T₁-weighted MRI data were employed at four stages of the analysis pipeline: 1) pretraining, with the UK Biobank sample (>10,000 individuals); 2) transfer learning and validation, with the ABIDE data sets (1,412 individuals, 5-56 years of age); 3) test and discovery, with the EU-AIMS/AIMS-2-TRIALS LEAP data set (681 individuals, 6-30 years of age); and 4) specificity, with the NeuroIMAGE and ADHD200 data sets (887 individuals, 7-26 years of age).

RESULTS

Across both ABIDE and LEAP, features positively predictive of neurotypical males were on average significantly more predictive of autistic males (ABIDE: Cohen's d=0.48; LEAP: Cohen's d=1.34). Features positively predictive of neurotypical females were on average significantly less predictive of autistic females (ABIDE: Cohen's d=1.25; LEAP: Cohen's d=1.29). These differences in sex prediction accuracy in autism were not observed in individuals with ADHD. In autistic females, the male-shifted neurophenotype was further associated with poorer social sensitivity and emotional face processing while also associated with gene expression patterns of midgestational cell types.

CONCLUSIONS

The results demonstrate an increased resemblance in both autistic male and female individuals' neuroanatomy with male-characteristic patterns associated with typically sex-differential social cognitive features and related gene expression patterns. The findings hold promise for future research aimed at refining the quest for biological mechanisms underpinning the etiology of autism.

Gene×environment interactions in autism spectrum disorders

There is credible evidence that environmental factors influence individual risk and/or severity of autism spectrum disorders (hereafter referred to as autism). While it is likely that environmental chemicals contribute to the etiology of autism via multiple mechanisms, identifying specific environmental factors that confer risk for autism and understanding how they contribute to the etiology of autism has been challenging, in part because the influence of environmental chemicals likely varies depending on the genetic substrate of the exposed individual. Current research efforts are focused on elucidating the mechanisms by which environmental chemicals interact with autism genetic susceptibilities to adversely impact neurodevelopment. The goal is to not only generate insights regarding the pathophysiology of autism, but also inform the development of screening platforms to identify specific environmental factors and gene×environment (G×E) interactions that modify autism risk. Data from such studies are needed to support development of intervention strategies for mitigating the burden of this neurodevelopmental condition on individuals, their families and society. In this review, we discuss environmental chemicals identified as putative autism risk factors and proposed mechanisms by which G×E interactions influence autism risk and/or severity using polychlorinated biphenyls (PCBs) as an example.

The safety of pediatric use of paracetamol (acetaminophen): a narrative review of direct and indirect evidence

Paracetamol (acetaminophen) use during pregnancy and early childhood was accepted as safe in the 1970s, but is now a subject of considerable concern. Careful analysis shows that initial acceptance of the drug was based on the false assumption that drug interactions in babies and adults are the same, and on a complete absence of knowledge regarding the impact of the drug on brain development. At least fourteen epidemiological studies now indicate that prenatal exposure to paracetamol is associated with neurodevelopmental problems. Based on these studies, it can be concluded that prenatal exposure to paracetamol causes statistically significant risks of developmental delays, attention deficit hyperactivity disorder, and a subtype of autism spectrum disorder (ASD) associated with hyperkinetic behavior. In contrast, data regarding postnatal exposure to paracetamol are limited, and several factors impede a classic multivariate analysis of epidemiologic data to resolve the issue. However, circumstantial evidence regarding postnatal exposure to the drug is abundant, and includes at least three otherwise unexplained temporal relationships, data from laboratory animal studies, several miscellaneous and otherwise unexplained correlations, and a lack of alternative suspects that fit the evidence-derived profile. Based on this evidence, it can be concluded without any reasonable doubt that oxidative stress puts some babies and children at risk of paracetamol-induced neurodevelopmental injury, and that postnatal exposure to paracetamol in those susceptible babies and children is responsible for many if not most cases of ASD.

Impacts of Gestational FireMaster 550 Exposure on the Neonatal Cortex Are Sex Specific and Largely Attributable to the Organophosphate Esters

INTRODUCTION

Flame retardants (FRs) are common bodily and environmental pollutants, creating concern about their potential toxicity. We and others have found that the commercial mixture FireMaster® 550 (FM 550) or its individual brominated (BFR) and organophosphate ester (OPFR) components are potential developmental neurotoxicants. Using Wistar rats, we previously reported that developmental exposure to FM 550 or its component classes produced sex- and compound-specific effects on adult socioemotional behaviors. The underlying mechanisms driving the behavioral phenotypes are unknown.

METHODS

To further mechanistic understanding, here we conducted transcriptomics in parallel with a novel lipidomics approach using cortical tissues from newborn siblings of the rats in the published behavioral study. Inclusion of lipid composition is significant because it is rarely examined in developmental neurotoxicity studies. Pups were gestationally exposed via oral dosing to the dam to FM 550 or the BFR or OPFR components at environmentally relevant doses.

RESULTS

The neonatal cortex was highly sexually dimorphic in lipid and transcriptome composition, and males were more significantly impacted by FR exposure. Multiple adverse modes of action for the BFRs and OPFRs on neurodevelopment were identified, with the OPFRs being more disruptive than the BFRs via multiple mechanisms including dysregulation of mitochondrial function and disruption of cholinergic and glutamatergic systems. Disrupted mitochondrial function by environmental factors has been linked to a higher risk of autism spectrum disorders and neurodegenerative disorders. Impacted lipid classes included ceramides, sphingomyelins, and triacylglycerides. Robust ceramide upregulation in the OPFR females could suggest a heightened risk of brain metabolic disease.

CONCLUSIONS

This study reveals multiple mechanisms by which the components of a common FR mixture are developmentally neurotoxic and that the OPFRs may be the compounds of greatest concern.

Sex differences in the functional topography of association networks in youth

Prior work has shown that there is substantial interindividual variation in the spatial distribution of functional networks across the cerebral cortex, or functional topography. However, it remains unknown whether there are sex differences in the topography of individualized networks in youth. Here, we leveraged an advanced machine learning method (sparsity-regularized non-negative matrix factorization) to define individualized functional networks in 693 youth (ages 8 to 23 y) who underwent functional MRI as part of the Philadelphia Neurodevelopmental Cohort. Multivariate pattern analysis using support vector machines classified participant sex based on functional topography with 82.9% accuracy (P < 0.0001). Brain regions most effective in classifying participant sex belonged to association networks, including the ventral attention, default mode, and frontoparietal networks. Mass univariate analyses using generalized additive models with penalized splines provided convergent results. Furthermore, transcriptomic data from the Allen Human Brain Atlas revealed that sex differences in multivariate patterns of functional topography were spatially correlated with the expression of genes on the X chromosome. These results highlight the role of sex as a biological variable in shaping functional topography.

Where Sex Meets Gender: How Sex and Gender Come Together to Cause Sex Differences in Mental Illness

Sex differences are prevalent in multiple mental disorders. Internalizing disorders are more commonly diagnosed in women, whereas externalizing and neurodevelopmental disorders are more often diagnosed in men. Significant sex/gender differences are reported in prevalence, symptom profile, age of onset, comorbidities, functional impairment, prognosis, as well as in responses to various treatments. In this conceptual article, we discuss theories and empirical studies of sex- and gender-related influences in mental health, by focusing on three examples: autism spectrum disorder (ASD), acknowledged as a disorder whose roots are mainly biological; eating disorders, whose origins are considered to be mainly psychosocial, and posttraumatic stress disorder (PTSD), an environmentally caused disorder with both psychosocial and biological underpinnings. We examine the ways in which sex differences emerge, from conception through adulthood. We also examine how gender dichotomies in exposures, expectations, role assumptions, and cultural traditions impact the expression of our three selected mental illnesses. We are especially interested in how sex-based influences and gender-based influences interact with one another to affect mental illness. We suggest that sex and gender are multi-faceted and complex phenomena that result in variations, not only between men and women, but also within each sex and gender through alterations in genes, hormone levels, self-perceptions, trauma experiences, and interpersonal relationships. Finally, we propose a conceptual diatheses-stress model, depicting how sex and gender come together to result in multiple sex/gender differences across mental disorders. In our model, we categorize diatheses into several categories: biological, intrapersonal, interpersonal, and environmental. These diatheses interact with exposure to stressors, ranging from relatively minor to traumatic, which allows for the sometimes bidirectional influences of acute and long-term stress responses. Sex and gender are discussed at every level of the model, thereby providing a framework for understanding and predicting sex/gender differences in expression, prevalence and treatment response of mental disorders. We encourage more research into this important field of study.

Bridging the Gap Between Environmental Adversity and Neuropsychiatric Disorders: The Role of Transposable Elements

Long regarded as “junk DNA,” transposable elements (TEs) have recently garnered much attention for their role in promoting genetic diversity and plasticity. While many processes involved in mammalian development require TE activity, deleterious TE insertions are a hallmark of several psychiatric disorders. Moreover, stressful events including exposure to gestational infection and trauma, are major risk factors for developing psychiatric illnesses. Here, we will provide evidence demonstrating the intersection of stressful events, atypical TE expression, and their epigenetic regulation, which may explain how neuropsychiatric phenotypes manifest. In this way, TEs may be the “bridge” between environmental perturbations and psychopathology.

Early Life Events and Maturation of the Dentate Gyrus: Implications for Neurons and Glial Cells

The dentate gyrus (DG), an important part of the hippocampus, plays a significant role in learning, memory, and emotional behavior. Factors potentially influencing normal development of neurons and glial cells in the DG during its maturation can exert long-lasting effects on brain functions. Early life stress may modify maturation of the DG and induce lifelong alterations in its structure and functioning, underlying brain pathologies in adults. In this paper, maturation of neurons and glial cells (microglia and astrocytes) and the effects of early life events on maturation processes in the DG have been comprehensively reviewed. Early postnatal interventions affecting the DG eventually result in an altered number of granule neurons in the DG, ectopic location of neurons and changes in adult neurogenesis. Adverse events in early life provoke proinflammatory changes in hippocampal glia at cellular and molecular levels immediately after stress exposure. Later, the cellular changes may disappear, though alterations in gene expression pattern persist. Additional stressful events later in life contribute to manifestation of glial changes and behavioral deficits. Alterations in the maturation of neuronal and glial cells induced by early life stress are interdependent and influence the development of neural nets, thus predisposing the brain to the development of cognitive and psychiatric disorders.

Exploring Sex-Related Differences in Microglia May Be a Game-Changer in Precision Medicine

One area of microglial biology that has been relatively neglected until recently is sex differences and this is in spite of the fact that sex is a risk factor in several diseases that are characterized by neuroinflammation and, by extension, microglial activation. Why these sex differences exist is not known but the panoply of differences extend to microglial number, genotype and phenotype. Significantly, several of these sex-related differences are also evident in health and change during life emphasizing the dynamic and plastic nature of microglia. This review will consider how age impacts on sex-related differences in microglia and ask whether the advancement of personalized medicine demands that a greater focus is placed on studying sex-related differences in microglia in Alzheimer's disease, Parkinson's disease and models of inflammatory stress and trauma in order to make true progress in dealing with these conditions.

Integrin β3 in forebrain Emx1-expressing cells regulates repetitive self-grooming and sociability in mice

Background

Autism spectrum disorder (ASD) is characterized by repetitive behaviors, deficits in communication, and overall impaired social interaction. Of all the integrin subunit mutations, mutations in integrin β3 (Itgb3) may be the most closely associated with ASD. Integrin β3 is required for normal structural plasticity of dendrites and synapses specifically in excitatory cortical and hippocampal circuitry. However, the behavioral consequences of Itgb3 function in the forebrain have not been assessed. We tested the hypothesis that behaviors that are typically abnormal in ASD—such as self-grooming and sociability behaviors—are disrupted with conditional Itgb3 loss of function in forebrain circuitry in male and female mice.

Methods

We generated male and female conditional knockouts (cKO) and conditional heterozygotes (cHET) of Itgb3 in excitatory neurons and glia that were derived from Emx1-expressing forebrain cells during development. We used several different assays to determine whether male and female cKO and cHET mice have repetitive self-grooming behaviors, anxiety-like behaviors, abnormal locomotion, compulsive-like behaviors, or abnormal social behaviors, when compared to male and female wildtype (WT) mice.

Results

Our findings indicate that only self-grooming and sociability are altered in cKO, but not cHET or WT mice, suggesting that Itgb3 is specifically required in forebrain Emx1-expressing cells for normal repetitive self-grooming and social behaviors. Furthermore, in cKO (but not cHET or WT), we observed an interaction effect for sex and self-grooming environment and an interaction effect for sex and sociability test chamber.

Limitations

While this study demonstrated a role for forebrain Itgb3 in specific repetitive and social behaviors, it was unable to determine whether forebrain Itgb3 is required for a preference for social novelty, whether cHET are haploinsufficient with respect to repetitive self-grooming and social behaviors, or the nature of the interaction effect for sex and environment/chamber in affected behaviors of cKO.

Conclusions

Together, these findings strengthen the idea that Itgb3 has a specific role in shaping forebrain circuitry that is relevant to endophenotypes of autism spectrum disorder.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-022-00691-2.

Sexual Dimorphism in Telomere Length in Childhood Autism

Autism spectrum disorders (ASD) are strikingly more prevalent in males, but the molecular mechanisms responsible for ASD sex-differential risk are poorly understood. Abnormally shorter telomeres have been associated with autism. Examination of relative telomere lengths (RTL) among non-syndromic male (N = 14) and female (N = 10) children with autism revealed that only autistic male children had significantly shorter RTL than typically-developing controls (N = 24) and paired siblings (N = 10). While average RTL of autistic girls did not differ significantly from controls, it was substantially longer than autistic boys. Our findings indicate a sexually-dimorphic pattern of RTL in childhood autism and could have important implications for RTL as a potential biomarker and the role/s of telomeres in the molecular mechanisms responsible for ASD sex-biased prevalence and etiology.

Sex-related brain connectivity correlates of compensation in adults with autism: insights into female protection

The male preponderance in autism spectrum disorder (ASD) led to the hypothesis that aspects of female biology are protective against ASD. Females with ASD (ASD-F) report more compensatory behaviors (i.e. "camouflaging") to overcome ASD-related social differences, which may be a mechanism of protection. No studies have examined sex-related brain pathways supporting camouflaging in ASD-F, despite its potential to inform mechanisms underlying the ASD sex bias. We used functional connectivity (FC) to investigate "sex-atypical" and "sex-typical" FC patterns linked to camouflaging in adults with ASD and examined multimodal coherence of findings via structural connectometry. Exploratory associations with cognitive/emotional functioning examined the adaptive nature of FC patterns. We found (i) "sex-atypical" FC patterns linked to camouflaging in the hypothalamus and precuneus and (ii) "sex-typical" patterns in the right anterior cingulate and anterior parahippocampus. Higher hypothalamic FC with a limbic reward cluster also correlated with better cognitive control/emotion recognition. Structural connectometry validated FC results with consistent brain pathways/effect patterns implicated in ASD-F. In summary, "male-typical" and "female-typical" brain connectivity patterns support camouflaging in ASD-F in circuits implicated in reward, emotion, and memory retrieval. "Sex-atypical" results are consistent with fetal steroidogenic/neuroinflammatory hypotheses. However, female genetics/biology may contribute to "female-typical" patterns implicated in camouflaging.

Cerebellar and Striatal Implications in Autism Spectrum Disorders: From Clinical Observations to Animal Models

Autism spectrum disorders (ASD) are complex conditions that stem from a combination of genetic, epigenetic and environmental influences during early pre- and postnatal childhood. The review focuses on the cerebellum and the striatum, two structures involved in motor, sensory, cognitive and social functions altered in ASD. We summarize clinical and fundamental studies highlighting the importance of these two structures in ASD. We further discuss the relation between cellular and molecular alterations with the observed behavior at the social, cognitive, motor and gait levels. Functional correlates regarding neuronal activity are also detailed wherever possible, and sexual dimorphism is explored pointing to the need to apprehend ASD in both sexes, as findings can be dramatically different at both quantitative and qualitative levels. The review focuses also on a set of three recent papers from our laboratory where we explored motor and gait function in various genetic and environmental ASD animal models. We report that motor and gait behaviors can constitute an early and quantitative window to the disease, as they often correlate with the severity of social impairments and loss of cerebellar Purkinje cells. The review ends with suggestions as to the main obstacles that need to be surpassed before an appropriate management of the disease can be proposed.

Sex/gender differences in children with autism spectrum disorder: A brief overview on epidemiology, symptom profile, and neuroanatomy

Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental conditions whose shared core features are impairments in social interaction and communication as well as restricted patterns of behavior, interests, and activities. The significant and consistent male preponderance in ASD prevalence has historically affected the scientific knowledge of autism in females as regards, inter alia, the clinical presentation, the genetic architecture, and the structural brain underpinnings. Indeed, females with ASD are under-investigated as samples recruited for clinical research typically reflect the strong male bias of the disorder. In the last years, the study of the various aspects of sex/gender (s/g) differences in ASD is gaining increased clinical and research interest resulting in a growing number of investigations on this topic. Here, I review and discuss evidence emerged from epidemiological, clinical, and neuroimaging studies in the last decade focusing on s/g differences in children with ASD. These studies are the prerequisites for the development of assessment and treatment practices which take into consideration s/g differences in ASD. Ultimately, a better understanding of s/g differences aims at improving healthcare for both ASD males and females.

Global prevalence of autism spectrum disorder and its gastrointestinal symptoms: A systematic review and meta-analysis

BACKGROUND

Autism spectrum disorder (ASD) is a severe public health concern, and Gastrointestinal (GI) symptoms are becoming more common among co-morbidities. The evidence has to be updated depending on differences in different parts of the world. This systematic review and meta-analysis aimed to better understand the existing epidemiological condition and help make health-related decisions.

METHODS

Searches in PubMed, Web of Science, Embase databases are limited to 14 March 2022. We reviewed the global prevalence of ASD and the prevalence of GI in people with ASD. Data were extracted by two independent researchers. Literature quality assessment using the National Institutes of Health Study Quality Assessment Tool.

RESULTS

We discovered that the global pooled prevalence of ASD was 98/10,000 (95% confidence interval, 95%CI: 81/10,000-118/10,000, I ² = 99.99%, p < 0.001), with 48.67% (95%CI: 43.50 -53.86, I ² = 99.51%) of individuals with ASD reporting GI symptoms. Based on the subgroup analyses, we found a higher prevalence of ASD in males (90/10,000, 95%CI: 71/10,000-112/10,000, I ² = 99.99%) than females (21/10,000, 95%CI: 15/10,000-27/10,000, I ² = 99.99%). Prevalence of pooling is higher in developing countries (155/10,000, 95% CI: 111/10,000-204/10,000, I ² = 99.87%) than in developed countries (85/10,000, 95%CI: 67/10,000-105/10,000, I ² = 99.99%).

CONCLUSION

The global prevalence of ASD and the prevalence of GI symptoms in ASD are both significant. The prevalence of ASD is much higher in men than in women. Further attention to ASD and its related comorbidities will be required in the future to inform coping strategy adaptation.

Autism-Like Behavior in the Offspring of CYP11A1-Overexpressing Pregnant Rats

Autism spectrum disorders (ASD) represent a complex group of neurodevelopmental disorders that are characterized by impaired social behavior and communication as well as repetitive behavior and restricted interests. Prenatal exposure to high levels of testosterone and preeclampsia are thought to be risk factors of ASD. We had previously reported that overexpression of the mitochondrial cholesterol side-chain cleavage enzyme (CYP11A1) could lead to both preeclampsia-like symptoms and increased testosterone levels in pregnant rats. In this study, we investigated the association between high CYP11A1 levels in pregnant rats and autism-like behavior in their offspring. Timed-pregnant Sprague-Dawley (SD) rats were injected with CYP11A1 gene-carrying adenoviruses on gestational day 8.5, and their offspring were then compared with those from timed-pregnant control SD rats. Compared with their control counterparts, the offspring of the CYP11A1-ovexpressing dams displayed more symptoms of anxiety and spent less time in social interactions and more time in self-grooming and rearing, all indicators of autism-like behavior. Sequencing of the transcriptome in primary microglia from the offspring of CYP11A1-overexpressing dams revealed that immune pathways were highly activated, and the gamma-aminobutyric acid type A (GABAA) receptor genes were among the top differentially expressed genes. Using primary microglia cultures generated from neonatal rats, tumor necrosis factor-alpha expression was found to be elevated in the cells transfected with CYP11A1-carrying adenoviruses. Additionally, the offspring of CYP11A1-overexpressing dams displayed dysregulated GABAA receptor expression. Taken together, these results suggest that abnormal CYP11A1 gene expression in pregnant rats could lead to microglial immune activation and dysregulated GABAA receptor expression in their offspring and thereby anxiety and autism-related behavior. Our study suggests that the pathways regulated by CYP11A1 could be promising preventative and therapeutic targets for ASD.

Age- and sex-specific effects of stress on parvalbumin interneurons in preclinical models: Relevance to sex differences in clinical neuropsychiatric and neurodevelopmental disorders

Stress is a major risk factor for neurodevelopmental and neuropsychiatric disorders, with the capacity to impact susceptibility to disease as well as long-term neurobiological and behavioral outcomes. Parvalbumin (PV) interneurons, the most prominent subtype of GABAergic interneurons in the cortex, are uniquely responsive to stress due to their protracted development throughout the highly plastic neonatal period and into puberty and adolescence. Additionally, PV + interneurons appear to respond to stress in a sex-specific manner. This review aims to discuss existing preclinical studies that support our overall hypothesis that the sex-and age-specific impacts of stress on PV + interneurons contribute to differences in individual vulnerability to stress across the lifespan, particularly in regard to sex differences in the diagnostic rate of neurodevelopmental and neuropsychiatric diseases in clinical populations. We also emphasize the importance of studying sex as a biological variable to fully understand the mechanistic and behavioral differences between males and females in models of neuropsychiatric disease.

Paracetamol use during pregnancy - a call for precautionary action

Paracetamol (N-acetyl-p-aminophenol (APAP), otherwise known as acetaminophen) is the active ingredient in more than 600 medications used to relieve mild to moderate pain and reduce fever. APAP is widely used by pregnant women as governmental agencies, including the FDA and EMA, have long considered APAP appropriate for use during pregnancy when used as directed. However, increasing experimental and epidemiological research suggests that prenatal exposure to APAP might alter fetal development, which could increase the risks of some neurodevelopmental, reproductive and urogenital disorders. Here we summarize this evidence and call for precautionary action through a focused research effort and by increasing awareness among health professionals and pregnant women. APAP is an important medication and alternatives for treatment of high fever and severe pain are limited. We recommend that pregnant women should be cautioned at the beginning of pregnancy to: forego APAP unless its use is medically indicated; consult with a physician or pharmacist if they are uncertain whether use is indicated and before using on a long-term basis; and minimize exposure by using the lowest effective dose for the shortest possible time. We suggest specific actions to implement these recommendations. This Consensus Statement reflects our concerns and is currently supported by 91 scientists, clinicians and public health professionals from across the globe.

Perinatal exposure to antibiotics reduces affiliative behavior after post-weaning in zebra finches (Taeniopygia guttata)

Social behavior is influenced by a host of factors, including the immune system; for example, song quality in male starlings predicts immunocompetence suggesting the development of the immune system is interconnected with aspects social development (Duffy and Ball, 2002). Treating birds with antibiotics during the perinatal period may alter this development, and thereby, social behaviors beyond song. We asked if antibiotic exposure during the perinatal period effected parenting and offspring social behavior (e.g. aggressive and affiliative behaviors) in zebra finches? We treated the drinking water of zebra finch parents and hatchlings from post-hatch day 5-14 with azithromycin or a vehicle control and monitored parenting/social behavior. After weaning, we transferred offspring from the breeding cage to group housing and monitored social behavior and integration into the colony by measuring aggressive and affiliative behaviors. For all treatments we saw a reduction in the number of songs performed by fathers, however, specifically for antibiotic treated offspring there was a reduction in affiliative behaviors relative to vehicle treated controls suggesting the immune system, perhaps via the guts microbiome, influences certain aspects of social behaviors in birds.

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.

Neural Contributions of the Hypothalamus to Parental Behaviour

Parental behaviour is a comprehensive set of neural responses to social cues. The neural circuits that govern parental behaviour reside in several putative nuclei in the brain. Melanin concentrating hormone (MCH), a neuromodulator that integrates physiological functions, has been confirmed to be involved in parental behaviour, particularly in crouching behaviour during nursing. Abolishing MCH neurons in innate MCH knockout males promotes infanticide in virgin male mice. To understand the mechanism and function of neural networks underlying parental care and aggression against pups, it is essential to understand the basic organisation and function of the involved nuclei. This review presents newly discovered aspects of neural circuits within the hypothalamus that regulate parental behaviours.

Protective effects of calcium ions via L-type calcium channels and NMDA receptors on prostaglandin E2-induced apoptosis in rat cortical cells

Calcium ions mediate a variety of physiological responses of developing neurons including survival. The purpose of this study was to examine the effect of calcium influx through L-type calcium channels (LTCCs) or NMDA receptors on prostaglandin E₂ (PGE₂)-induced apoptosis in rat cortical cells. Cultures of rat cortical cells were prepared from an embryonic day 18 rat neocortex. After culturing for 2 or 8 days in vitro (DIV), the cells were subjected to PGE₂ treatment for 48 h. FPL64176, an LTCC agonist, protected the cells at 2 and 8 DIV from PGE₂-induced apoptosis. On the other hand, N-methyl-D-aspartate (NMDA), an agonist of NMDA receptor, protected the cells from PGE₂-induced apoptosis only at 8 DIV. FPL64176 increased the calcium levels at 2 and 8 DIV, whereas NMDA increased the calcium levels only at 8 DIV. The protective effects of the LTCC agonist and NMDA on PGE₂-induced apoptosis were blocked following treatment of the cells with protein kinase C inhibitors. Our results suggest that LTCCs and NMDA receptors modulate the cell death of developing cortical neurons possibly through a protein kinase C pathway.

Diagnostic Tools for Autism Spectrum Disorders by Gender: Analysis of Current Status and Future Lines

Studies on the prevalence of autism spectrum disorders have shown gender disproportion. In recent years, there has been an increasing interest in this investigation area. There are two main research lines; the first is focused mostly on gender-related biological reasons that could account for low ASD prevalence in women (i.e., related to some protective factors related to hormones or the immune system, among others), and the second research line studies possible diagnostic biases. In the present study, a review of the latter line of research is made based on two main objectives: (a) analysis of possible biases in diagnostic tools and (b) other nonbiological ASD prevalence explained by gender differences. As a result of our theoretical review, we found that the articles reviewed showed contradictory results and possible diagnostic biases, not only in their design but also in their assessment standards. We concluded that specific or complementary diagnostic tools and procedures differentiated by gender should be developed in order to reduce these biases.

Implications for microglial sex differences in tau-related neurodegenerative diseases

Tauopathies are a group of neurodegenerative diseases that involve pathological changes to the tau protein. Neuroinflammation is a commonly reported feature of tauopathies that has been demonstrated to exacerbate tau pathology and, hence, neurodegeneration. Microglia can mediate the inflammatory response in order to maintain brain homeostasis. In the aged brain, microglia are reported to undergo morphological and functional changes, adopting a pro-inflammatory profile and loss of homeostatic functions. Dystrophic and dysfunctional microglia are associated with tau pathology in the healthy and diseased brain which is proposed to contribute to disease development and progression. Microglia have also been recently demonstrated to possess sexually dimorphic roles in the developing, adult and aged brain. The sex differences in microglial functionality suggest that microglia may contribute to tauopathies which may differ between sexes. This review highlights the detrimental loop between age-related microglial changes and tau pathology with implications for microglial sexual dichotomy.

Quantitative and Qualitative Sex Modulations in the Brain Anatomy of Autism

BACKGROUND

Sex-based neurobiological heterogeneity in autism is poorly understood. Research is disproportionately biased to males, leading to an unwarranted presumption that autism neurobiology is the same across sexes. Previous neuroimaging studies using amalgamated multicenter datasets to increase autistic female samples are characterized by large statistical noise.

METHODS

We used a better-powered dataset of 1183 scans of 839 individuals-299 (467 scans) autistic males, 74 (102 scans) autistic females, 240 (334 scans) control males, and 226 (280 scans) control females-to test two whole-brain models of overall/global sex modulations on autism neuroanatomy, by summary measures computed across the brain: the local magnitude model, in which the same brain regions/circuitries are involved across sexes but effect sizes are larger in females, indicating quantitative sex modulation; and spatial dissimilarity model, in which the neuroanatomy differs spatially between sexes, indicating qualitative sex modulation. The male and female autism groups were matched on age, IQ, and autism symptoms. Autism brain features were defined by comparisons with same-sex control individuals.

RESULTS

Across five metrics (cortical thickness, surface area, volume, mean absolute curvature, and subcortical volume), we found no evidence supporting the local magnitude model. We found indicators supporting the spatial dissimilarity model on cortical mean absolute curvature and subcortical volume, but not on other metrics.

CONCLUSIONS

The overall/global autism neuroanatomy in females and males does not simply differ quantitatively in the same brain regions/circuitries. They may differ qualitatively in spatial involvement in cortical curvature and subcortical volume. The neuroanatomy of autism may be partly sex specific. Sex stratification to inform autism preclinical/clinical research is needed to identify sex-informed neurodevelopmental targets.

Early estradiol exposure masculinizes disease-relevant behaviors in female mice

Most psychiatric disorders show a sex bias in incidence, symptomatology, and/or response to treatment. Males are more susceptible to neurodevelopmental disorders including autism spectrum disorder and attention-deficit activity disorder, while women are more prone to major depressive disorder and anxiety disorders after puberty. A striking difference between males and females in humans and other mammals is that males undergo a process of brain masculinization due to the early exposure to gonadal hormones. In rodents, this developmental organization of the brain is essential for adult males to express the appropriate sexual behaviors in the presence of a receptive female. Our goal was to determine whether this process of brain masculinization influences behaviors relevant to psychiatric disorders. To this aim, we studied sex differences and the effect of neonatal 17β-estradiol benzoate treatment of female mice on different disease-relevant behaviors. Our analysis includes postnatal behavior, juvenile play, and adult tests for sociability, repetitive behaviors, anxiety, and depression. Our results show that the sex differences observed in exploration, repetitive behaviors, and depression-related behaviors are largely reduced when females are neonatally treated with 17β-estradiol benzoate. These results suggest a role of neonatal sex steroids in the development of disease-relevant behaviors and provide evidence supporting a role for perinatal exposure to estrogens and androgens on the development and manifestation of psychiatric disorders.

Alterations in Chromatin Structure and Function in the Microglia

Microglia are resident immune cells in the central nervous system (CNS). Microglia exhibit diversity in their morphology, density, electrophysiological properties, and gene expression profiles, and play various roles in neural development and adulthood in both physiological and pathological conditions. Recent transcriptomic analysis using bulk and single-cell RNA-seq has revealed that microglia can shift their gene expression profiles in various contexts, such as developmental stages, aging, and disease progression in the CNS, suggesting that the heterogeneity of microglia may be associated with their distinct functions. Epigenetic changes, including histone modifications and DNA methylation, coordinate gene expression, thereby contributing to the regulation of cellular state. In this review, we summarize the current knowledge regarding the epigenetic mechanisms underlying spatiotemporal and functional diversity of microglia that are altered in response to developmental stages and disease conditions. We also discuss how this knowledge may lead to advances in therapeutic approaches for diseases.

Maternal acute and chronic inflammation in pregnancy is associated with common neurodevelopmental disorders: a systematic review

Inflammation is increasingly recognized as a cause or consequence of common problems of humanity including obesity, stress, depression, pollution and disease states such as autoimmunity, asthma, and infection. Maternal immune activation (MIA), triggered by both acute and systemic chronic inflammation, is hypothesized to be one of the mechanisms implicated in the pathogenesis of neurodevelopmental disorders (NDD). Although there is substantial preclinical evidence to support the MIA hypothesis, the human evidence is disparate. We performed a systematic review on human studies examining associations between maternal inflammatory states and offspring NDDs (autism spectrum disorder- ASD, attention deficit hyperactivity disorder-ADHD, Tourette syndrome-TS). 32 meta-analyses and 26 additional individual studies were identified. Maternal states associated with ASD include obesity, gestational diabetes mellitus, pre-eclampsia, pollution, stress, depression, autoimmune diseases, and infection. Maternal states associated with ADHD include obesity, pre-eclampsia, smoking, low socioeconomic status (SES), stress, autoimmune disease, and asthma. Maternal states associated with TS include low SES, depression, and autoimmune diseases. Diverse maternal inflammatory states in pregnancy are associated with common offspring NDDs. Given the increased prevalence of NDDs, there is urgent need to explore relative and cumulative maternal risk factors and disease mechanisms. Defining preventable risk factors in high-risk pregnancies could mitigate the expression and severity of NDDs.

Sexually dimorphic neuroanatomical differences relate to ASD-relevant behavioral outcomes in a maternal autoantibody mouse model

Immunoglobulin G (IgG) autoantibodies reactive to fetal brain proteins in mothers of children with ASD have been described by several groups. To understand their pathologic significance, we developed a mouse model of maternal autoantibody related ASD (MAR-ASD) utilizing the peptide epitopes from human autoantibody reactivity patterns. Male and female offspring prenatally exposed to the salient maternal autoantibodies displayed robust deficits in social interactions and increased repetitive self-grooming behaviors as juveniles and adults. In the present study, neuroanatomical differences in adult MAR-ASD and control offspring were assessed via high-resolution ex vivo magnetic resonance imaging (MRI) at 6 months of age. Of interest, MAR-ASD mice displayed significantly larger total brain volume and of the 159 regions examined, 31 were found to differ significantly in absolute volume (mm³) at an FDR of <5%. Specifically, the absolute volumes of several white matter tracts, cortical regions, and basal nuclei structures were significantly increased in MAR-ASD animals. These phenomena were largely driven by female MAR-ASD offspring, as no significant differences were seen with either absolute or relative regional volume in male MAR-ASD mice. However, structural covariance analysis suggests network-level desynchronization in brain volume in both male and female MAR-ASD mice. Additionally, preliminary correlational analysis with behavioral data relates that volumetric increases in numerous brain regions of MAR-ASD mice were correlated with social interaction and repetitive self-grooming behaviors in a sex-specific manner. These results demonstrate significant sex-specific effects in brain size, regional relationships, and behavior for offspring prenatally exposed to MAR-ASD autoantibodies relative to controls.

Phenotypic Subtyping and Re-analyses of Existing Transcriptomic Data from Autistic Probands in Simplex Families Reveal Differentially Expressed and ASD Trait-Associated Genes

Autism spectrum disorder (ASD) describes a collection of neurodevelopmental disorders characterized by core symptoms that include social communication deficits and repetitive, stereotyped behaviors often coupled with restricted interests. Primary challenges to understanding and treating ASD are the genetic and phenotypic heterogeneity of cases that complicates all omics analyses as well as a lack of information on relationships among genes, pathways, and autistic traits. In this study, we re-analyze existing transcriptomic data from simplex families by subtyping individuals with ASD according to multivariate cluster analyses of clinical ADI-R scores that encompass a broad range of behavioral symptoms. We also correlate multiple ASD traits, such as deficits in verbal and non-verbal communication, play and social skills, ritualistic behaviors, and savant skills, with expression profiles using Weighted Gene Correlation Network Analyses (WGCNA). Our results show that subtyping greatly enhances the ability to identify differentially expressed genes involved in specific canonical pathways and biological functions associated with ASD within each phenotypic subgroup. Moreover, using WGCNA, we identify gene modules that correlate significantly with specific ASD traits. Network prediction analyses of the genes in these modules reveal canonical pathways as well as neurological functions and disorders relevant to the pathobiology of ASD. Finally, we compare the WGCNA-derived data on autistic traits in simplex families with analogous data from multiplex families using transcriptomic data from our previous studies. The comparison reveals overlapping trait-associated pathways as well as upstream regulators of the module-associated genes that may serve as useful targets for a precision medicine approach to ASD.