Abnormal instability, excess density, and aberrant morphology of dendritic spines in prenatally testosterone-exposed mice

Sex-specific dendritic morphology of hippocampal pyramidal neurons in the adolescent and young adult rats

CA1 and CA3 pyramidal neurons are the major sources of hippocampal efferents. The structural features of these neurons are presumed to be involved in various normal/abnormal cognitive and emotional outcomes by influencing the pattern of synaptic inputs and neuronal signal processing. Although many studies have described hippocampal structure differences between males and females, these reports mainly focused on gross anatomical features in adult or aged models, and such distinctions on neuronal morphology and dendritic spine density during adolescence, a period of high vulnerability to neurodevelopmental disorders, have received much less attention. In this work, we analyzed dendritic architecture and density of spines in CA1 and CA3 neurons of male and female rats in early adolescence (postnatal day, PND 40) and compared them with those in late adolescence/young adulthood (PND 60). On PND 40, CA1 neurons of male rats showed more Sholl intersections and spine density in apical and basal dendrites compared to those in females. The Sholl intersections in basal dendrites of CA3 neurons were also more in males, whereas the number of apical dendrite intersections was not significantly different between sexes. In male rats, there was a notable decrease in the number of branch and terminal points in the basal dendrite of CA1 neurons of young adults when compared to their sex-matched adolescent rats. On the other hand, CA1 neurons in young adult females also showed more Sholl intersections in apical and basal dendrites compared to adolescent females. Meanwhile, the total cable length, the number of branches, and terminal points of apical dendrites in CA3 neurons also exhibited a significant reduction in young adult male rats compared to their sex-matched adolescents. In young adult rats, both apical and basal dendrites of CA3 neurons in males showed fewer intersections with Sholl circles, but there were no significant differences in dendritic spine density or count estimation between males and females. On the other hand, young adult female rats had more Sholl intersections and dendritic spine count on the basal dendrites of CA3 neurons compared to adolescent females. Although no significant sex- and age-dependent difference in neuronal density was detected in CA1 and CA3 subareas, CA3 pyramidal neurons of both male and female rats showed reduced soma area compared to adolescent rats. Our findings show that the sex differences in the dendritic structure of CA1 and CA3 neurons vary by age and also by the compartments of dendritic arbors. Such variations in the morphology of hippocampal pyramidal neurons may take part as a basis for normal cognitive and affective differences between the sexes, as well as distinct sensitivity to interfering factors and the prevalence of neuropsychological diseases.

Exposures during pregnancy and at birth are associated with the risk of offspring eating disorders

BACKGROUND

Eating disorders (ED) are severe psychiatric disorders, commonly debuting early. Aberrances in the intrauterine environment and at birth have been associated with risk of ED. Here, we explore if, and at what effect size, a variety of such exposures associate with offspring ED, that is, anorexia nervosa (AN), bulimia nervosa (BN), and eating disorder not otherwise specified (EDNOS).

METHODS

This population-based cohort study, conducted from September 2021 to August 2023, used Finnish national registries of all live births in 1996-2014 (N = 1,097,753). Cox proportional hazards modeling was used to compare ED risk in exposed versus unexposed offspring, adjusting for potential confounders and performing sex-stratified analyses.

RESULTS

A total of 6614 offspring were diagnosed with an ED; 3668 AN, 666 BN, and 4248 EDNOS. Lower risk of offspring AN was seen with young mothers, continued smoking, and instrumental delivery, while higher risk was seen with older mothers, inflammatory disorders, prematurity, small for gestational age, and low Apgar. Offspring risk of BN was higher with continued smoking and prematurity, while lower with postmature birth. Offspring risk of EDNOS was lower with instrumental delivery, higher for older mothers, polycystic ovary syndrome, insulin-treated pregestational diabetes, antibacterial treatment, prematurity, and small for gestational age. Sex-specific associations were found.

CONCLUSIONS

Several prenatal and at birth exposures are associated with offspring ED; however, we cannot exclude confounding by maternal BMI. Nevertheless, several exposures selectively associate with risk of either AN, BN, or EDNOS, and some are sex-specific, emphasizing the importance of subtype- and sex-stratified analyses of ED.

PUBLIC SIGNIFICANCE

We define environmental factors involved in the development of different ED, of importance as preventive measure, but also in order to aid in defining the molecular pathways involved and thus in the longer perspective contribute to the development of pharmacological treatment of ED.

Prenatal Sex Hormone Exposure Is Associated with the Development of Autism Spectrum Disorder

Sexual differentiation is a major developmental process. Sex differences resulting from sexual differentiation have attracted the attention of researchers. Unraveling what contributes to and underlies sex differences will provide valuable insights into the development of neurodevelopmental disorders that exhibit sex biases. Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects an individual's social interaction and communication abilities, and its male preponderance has been consistently reported in clinical studies. The etiology of male preponderance remains unclear, but progress has been made in studying prenatal sex hormone exposure. The present review examined studies that focused on the association between prenatal testosterone exposure and ASD development, as well as sex-specific behaviors in individuals with ASD. This review also included studies on maternal immune activation-induced developmental abnormalities that also showed striking sex differences in offspring and discussed its possible interacting roles in ASD so as to present a potential approach for future studies on sex biases in ASD.

Maternal polycystic ovary syndrome and the potential risk of attention-deficit/hyperactivity disorder and autism spectrum disorder in the offspring: a systematic review and meta-analysis

OBJECTIVE

Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) are two increasing important problems among children. This study aims to explore the link between maternal polycystic ovary syndrome (PCOS) and the risk of ASD and ADHD in the offspring.

METHOD

The MOOSE guidelines were followed in the conduct of this meta-analysis. A literature search was done in PubMed/MEDLINE, Scopus, and Web of Science from inception until January 2021. The DerSimonian and Laird random-effects model was used to estimate the combined risk ratios (RR) and 95% confidence intervals (CI). Sensitivity analysis was also used to investigate the effect of each study on the combined results.

RESULTS

Seven studies, with 1,358,696 participants, comprising 7,334 ADHD cases and 3,920 ASD cases, were included in this study. Children born to mothers with maternal PCOS had higher risks of developing ASD (RR = 1.46, 95% CI: 1.26-1.69, I² = 64%) and ADHD (RR = 1.43, 95% CI: 1.35-1.41, I² = 0%) when compared with children born to mothers without maternal PCOS.

CONCLUSION

This study showed that there might be a link between maternal PCOS and the risk of developing ASD and ADHD in the offspring. This important issue must be considered in PCOS women during and after pregnancy.

Association of polycystic ovary syndrome or anovulatory infertility with offspring psychiatric and mild neurodevelopmental disorders: a Finnish population-based cohort study

STUDY QUESTION

Is maternal polycystic ovary syndrome (PCOS) associated with increased risks for a broad spectrum of psychiatric and mild neurodevelopmental disorders in offspring?

SUMMARY ANSWER

Maternal PCOS and/or anovulatory infertility is independently, and jointly with maternal obesity, perinatal problems, cesarean delivery and gestational diabetes, associated with increased risks in offspring for almost all groups of psychiatric and mild neurodevelopmental disorders with onset in childhood or adolescence.

WHAT IS KNOWN ALREADY

Maternal PCOS was previously associated with autism spectrum disorder, attention-deficit/hyperactivity disorders and possibly developmental delay in offspring. Few studies have investigated the association between maternal PCOS and other psychiatric and neurodevelopmental disorders in offspring.

STUDY DESIGN, SIZE, DURATION

This was a population-based cohort study in Finland including all live births between 1996 and 2014 (n = 1 105 997). After excluding births to mothers with symptoms similar to PCOS, a total of 1 097 753 births by 590 939 mothers remained. Children were followed up until 31 December 2018, i.e. up to the age of 22 years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

National registries were used to link data of the included births and their mothers. Data from 24 682 (2.2%) children born to mothers with PCOS were compared with 1 073 071 (97.8%) children born to mothers without PCOS. Cox proportional hazards modeling was used to evaluate the hazard ratio (HR) and 95% CI for the risk of neuropsychiatric disorders in relation to maternal PCOS. Stratified analyses were performed to test the independent role of PCOS and the joint effects of PCOS with maternal obesity, perinatal problems, cesarean delivery, gestational diabetes and use of fertility treatment. The analysis was adjusted for maternal age, country of birth, marriage status at birth, smoking, parity, psychiatric disorders, prescription of psychotropic N05/N06 during pregnancy and systemic inflammatory diseases when applicable.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 105 409 (9.8%) children were diagnosed with a neurodevelopmental or psychiatric disorder. Firstly, maternal PCOS was associated with any psychiatric diagnosis (HR 1.32; 95% CI 1.27-1.38) in offspring. Particularly, the risk was increased for sleeping disorders (HR 1.46; 95% CI 1.27-1.67), attention-deficit/hyperactivity disorders and conduct disorders (HR 1.42; 95% CI 1.33-1.52), tic disorders (HR 1.42; 95% CI 1.21-1.68), intellectual disabilities (HR 1.41; 95% CI 1.24-1.60), autism spectrum disorder (HR 1.40; 95% CI 1.26-1.57), specific developmental disorders (HR 1.37; 95% CI 1.30-1.43), eating disorders (HR 1.36; 95% CI 1.15-1.61), anxiety disorders (HR 1.33; 95% CI 1.26-1.41), mood disorders (HR 1.27; 95% CI 1.18-1.35) and other behavioral and emotional disorders (ICD-10 F98, HR 1.49; 95% CI 1.39-1.59). In short, there was no significant difference between sexes. The results were robust when restricting the analyses to the first-born children or births to mothers without psychiatric diagnosis or purchase of psychotropic medication. Secondly, stratified analysis according to maternal BMI showed that the risk of any neuropsychiatric disorder was increased in offspring to normal-weight mothers with PCOS (HR 1.20; 95% CI 1.09-1.32), and markedly higher in those to severely obese mothers with PCOS (HR 2.11; 95% CI 1.76-2.53) compared to offspring to normal-weight mothers without PCOS. When excluding perinatal problems, mothers with PCOS were still associated with increased risks of any neuropsychiatric disorders in offspring (HR 1.28; 95% CI 1.22-1.34) compared to mothers without PCOS. However, an additional increase was observed for PCOS in combination with perinatal problems (HR 1.99; 95% CI 1.84-2.16). Likewise, excluding cases with maternal gestational diabetes (HR 1.30; 95% CI 1.25-1.36), cesarean delivery (HR 1.29; 95% CI 1.23-1.35) or fertility treatment (HR 1.31; 95% CI 1.25-1.36) did not eliminate the associations.

LIMITATIONS, REASONS FOR CAUTION

The register-based prevalence of PCOS was lower than previously reported, suggesting that this study may capture the most severe cases. To combine anovulatory infertility with PCOS diagnosis as PCOS exposure might introduce diagnostic bias. It was not feasible to distinguish between subtypes of PCOS. Furthermore, familial factors might confound the association between maternal PCOS and neuropsychiatric disorders in offspring. Maternal BMI was available for birth cohort 2004-2014 only and there was no information on gestational weight gain.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides further evidence that maternal PCOS and/or anovulatory infertility, independently and jointly with maternal obesity, perinatal problems, gestational diabetes and cesarean delivery, implies a broad range of adverse effects on offspring neurodevelopment. These findings may potentially help in counseling and managing pregnancies.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the joint research funding of Shandong University and Karolinska Institute (SDU-KI-2019-08 to X.C and C.L.), THL Finnish Institute for Health and Welfare: Drug and pregnancy project [M.G.], the Swedish Research Council [2014-10171 to C.L.], the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institute Stockholm County Council [SLL20170292 to C.L.], the Swedish Brain Foundation [FO2018-0141 and FO2019-0201 to C.L.]. X.C. was supported by the China Scholarship Council during her training in Karolinska Institute. L.K. was supported by the China Scholarship Council for his PhD study in Karolinska Institute. The authors have no competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Androgenic regulation of sexually dimorphic expression of RNA binding motif protein 48 in the developing mouse cortex and hippocampus

To further reveal the molecular mechanism underlying sexual differentiation of the mouse cerebral cortex and hippocampus, we reanalyzed our previous microarray study with Gene Ontology (GO) term enrichment and found that the GO term "RNA binding" was over-represented among the 89 sexually dimorphic candidate genes. Thus, we selected 16 autosomal genes annotated to the term RNA binding and profiled their mRNA expression in the developing male and female mouse cortex/hippocampus. During the first three weeks after birth, sex differences in mRNA levels of Khdrbs2, Nanos2, Rbm48, and Tdrd3 were observed in the mouse cortex/hippocampus. Of these genes, only the female-biased expression of Rbm48 in neonates was abolished by prenatal exposure to testosterone propionate (TP), while postnatal treatment of TP three weeks after birth increased Rbm48 and Tdrd3 mRNA levels in both sexes. Regardless of sex, the postnatal cortex/hippocampus also showed a marked increase in the content of androgen receptor (Ar) and estrogen receptor β (Esr2), but a decrease in estrogen receptor α (Esr1) and aromatase (Cyp19a1), which might confer the different responses of Rbm48 to prenatal and postnatal TP. Our results suggest that androgen-regulated, sexually dimorphic Rbm48 expression might present a novel molecular mechanism by which perinatal androgens control development of sexual dimorphism in cortical and hippocampal structure and function.

Genetic Causes and Modifiers of Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is one of the most prevalent neurodevelopmental disorders, affecting an estimated 1 in 59 children. ASD is highly genetically heterogeneous and may be caused by both inheritable and de novo gene variations. In the past decade, hundreds of genes have been identified that contribute to the serious deficits in communication, social cognition, and behavior that patients often experience. However, these only account for 10-20% of ASD cases, and patients with similar pathogenic variants may be diagnosed on very different levels of the spectrum. In this review, we will describe the genetic landscape of ASD and discuss how genetic modifiers such as copy number variation, single nucleotide polymorphisms, and epigenetic alterations likely play a key role in modulating the phenotypic spectrum of ASD patients. We also consider how genetic modifiers can alter convergent signaling pathways and lead to impaired neural circuitry formation. Lastly, we review sex-linked modifiers and clinical implications. Further understanding of these mechanisms is crucial for both comprehending ASD and for developing novel therapies.

Sex Differences in Autism Spectrum Disorder: a Review

PURPOSE OF REVIEW

Neurodevelopmental disorders disproportionately affect males. The mechanisms underlying male vulnerability or female protection are not known and remain understudied. Determining the processes involved is crucial to understanding the etiology and advancing treatment of neurodevelopmental disorders. Here, we review current findings and theories that contribute to male preponderance of neurodevelopmental disorders, with a focus on autism.

RECENT FINDINGS

Recent work on the biological basis of the male preponderance of autism and other neurodevelopmental disorders includes discussion of a higher genetic burden in females and sex-specific gene mutations or epigenetic changes that differentially confer risk to males or protection to females. Other mechanisms discussed are sex chromosome and sex hormone involvement. Specifically, fetal testosterone is involved in many aspects of development and may interact with neurotransmitter, neuropeptide, or immune pathways to contribute to male vulnerability. Finally, the possibilities of female underdiagnosis and a multi-hit hypothesis are discussed. This review highlights current theories of male bias in developmental disorders. Topics include environmental, genetic, and epigenetic mechanisms; theories of sex chromosomes, hormones, neuroendocrine, and immune function; underdiagnosis of females; and a multi-hit hypothesis.

Maturation, Refinement, and Serotonergic Modulation of Cerebellar Cortical Circuits in Normal Development and in Murine Models of Autism

The formation of the complex cerebellar cortical circuits follows different phases, with initial synaptogenesis and subsequent processes of refinement guided by a variety of mechanisms. The regularity of the cellular and synaptic organization of the cerebellar cortex allowed detailed studies of the structural plasticity mechanisms underlying the formation of new synapses and retraction of redundant ones. For the attainment of the monoinnervation of the Purkinje cell by a single climbing fiber, several signals are involved, including electrical activity, contact signals, homosynaptic and heterosynaptic interaction, calcium transients, postsynaptic receptors, and transduction pathways. An important role in this developmental program is played by serotonergic projections that, acting on temporally and spatially regulated postsynaptic receptors, induce and modulate the phases of synaptic formation and maturation. In the adult cerebellar cortex, many developmental mechanisms persist but play different roles, such as supporting synaptic plasticity during learning and formation of cerebellar memory traces. A dysfunction at any stage of this process can lead to disorders of cerebellar origin, which include autism spectrum disorders but are not limited to motor deficits. Recent evidence in animal models links impairment of Purkinje cell function with autism-like symptoms including sociability deficits, stereotyped movements, and interspecific communication by vocalization.

Disturbance in Maternal Environment Leads to Abnormal Synaptic Instability during Neuronal Circuitry Development

Adverse maternal environment during gestation and lactation can have negative effects on the developing brain that persist into adulthood and result in behavioral impairment. Recent studies of human and animal models suggest epidemiological and experimental association between disturbances in maternal environments during brain development and the occurrence of neuropsychiatric disorders, including autism spectrum disorder, attention deficit hyperactivity disorder, schizophrenia, anxiety, depression, and neurodegenerative diseases. In this review, we summarize recent advances in understanding the effects of maternal metabolic and hormonal abnormalities on the developing brain by focusing on the dynamics of dendritic spine, an excitatory postsynaptic structure. We discuss the abnormal instability of dendritic spines that is common to developmental disorders and neurological diseases. We also introduce our recent studies that demonstrate how maternal obesity and hyperandrogenism leads to abnormal development of neuronal circuitry and persistent synaptic instability, which results in the loss of synapses. The aim of this review is to highlight the links between abnormal maternal environment, behavioral impairment in offspring, and the dendiric spine pathology of neuropsychiatric disorders.

Clustered structural and functional plasticity of dendritic spines

The configuration of synaptic circuits underlies their ability to process and store information. Research on dendritic spines has revealed that their structural and functional alterations are clustered along the parent dendrite. Here we review the evidence supporting such notion of clustered synaptic plasticity, discuss its functional implications and possible contributing factors, and suggest potential strategies to deal with open challenges.

Protection from ischemia by preconditioning, postconditioning, and combined treatment in rabbit testicular ischemia reperfusion injury

This study aimed to investigate the protection of ischemic preconditioning (IPreC), ischemic postconditioning (IPostC) and combined treatment on ischemia reperfusion injury (IRI) of testis. A rabbit testicular ischemia reperfusion (IR) model was established with determining of rabbit serum testosterone, nitric oxide (NO), malondialdehyde (MDA), protein carbonyl (PC), superoxide dismutase (SOD), myeloperoxidase (MPO), glutathione peroxidase (GSH-Px), and tissues pathology. After IR, the NO, MDA, PC, SOD, MPO, and GSH-Px expression significantly increased in torsive testis, and significantly decreased after IPreC, IPostC, and combined treatment in torsive testis when compared to contralateral testis. In torsive testis, testicular tissues was severely damaged with spermatogenic cells disappearing, and were filled with light eosin edema liquid. Cell apoptosis index significantly increased, and the ratio of Bcl-2/Bax significantly decreased. After IPreC, IPostC, and combined treatment, testicular tissues were restored to normal, cell apoptosis index significantly decreased, and the ratio of Bcl-2/Bax significantly increased. It indicates that IPreC, IPostC, and combined treatment has an obvious protective effect on testicular IRI, by decreasing the oxidative stress index and cell apoptosis, provides a significant reference for the treatment of testicular torsion induced infertility, and exhibits a great value in clinical applications.