Sex Differences in Autism-Like Behavioral Phenotypes and Postsynaptic Receptors Expression in the Prefrontal Cortex of TERT Transgenic Mice

Parental age at birth, telomere length, and autism spectrum disorders in the UK Biobank cohort

Older parental age at birth is associated with increased risk of autism spectrum disorders (ASD) in offspring. Independently, shorter telomere length (TL) has also been shown to be associated with ASD in children. However, older paternal age at birth, with or without controlling for maternal age, has been associated with longer TL, a seemingly contradictory finding. Here, we conducted a retrospective cohort study among participants in the UK Biobank to disentangle associations between leukocyte TL and ASD status in adults, and the potential moderation by parental age on adult offspring's TL. Participants with ASD diagnosis (N = 87) with a mean age of 46.0 (SD 4.4) years were matched to participants without ASD diagnosis (N = 870) based on age, sex, ethnicity, education, household income, and assessment center. No statistically significant differences were seen in TL between participants with and without ASD when parental age at birth was not considered. However, there was a significant interaction between ASD diagnostic status and parental age on participants' TL, such that older paternal or maternal age at birth was more strongly associated with longer TL in participants with ASD. This study suggests that the shortened TL observed in children with ASD in previous research may partially depend on parental age at birth. Future studies tracking TL attrition before ASD diagnosis are warranted to depict temporal associations and the interacting effects of parental age at birth and ASD status on TL across the lifespan.

Sex shapes gut-microbiota-brain communication and disease

Research into the microbiota-gut-brain axis (MGBA) has entered a golden age, raising the hope that therapeutics acting on it may offer breakthroughs in the treatment of many illnesses. However, most of this work overlooks a fundamental, yet understudied, biological variable: sex. Sex differences exist at every level of the MGBA. Sex steroids shape the structure of the gut microbiota, and these microbes in turn regulate levels of bioactive sex steroids. These hormones and microbes act on gut sensory enteroendocrine cells, which modulate downstream activity in the enteric nervous system, vagus nerve, and brain. We examine recent advances in this field, and discuss the scientific and moral imperative to include females in biomedical research, using autism spectrum disorder (ASD) as an example.

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.

Loss of GABA co-transmission from cholinergic neurons impairs behaviors related to hippocampal, striatal, and medial prefrontal cortex functions

Introduction: Altered signaling or function of acetylcholine (ACh) has been reported in various neurological diseases, including Alzheimer's disease, Tourette syndrome, epilepsy among others. Many neurons that release ACh also co-transmit the neurotransmitter gamma-aminobutyrate (GABA) at synapses in the hippocampus, striatum, substantia nigra, and medial prefrontal cortex (mPFC). Although ACh transmission is crucial for higher brain functions such as learning and memory, the role of co-transmitted GABA from ACh neurons in brain function remains unknown. Thus, the overarching goal of this study was to investigate how a systemic loss of GABA co-transmission from ACh neurons affected the behavioral performance of mice. Methods: To do this, we used a conditional knock-out mouse of the vesicular GABA transporter (vGAT) crossed with the ChAT-Cre driver line to selectively ablate GABA co-transmission at ACh synapses. In a comprehensive series of standardized behavioral assays, we compared Cre-negative control mice with Cre-positive vGAT knock-out mice of both sexes. Results: Loss of GABA co-transmission from ACh neurons did not disrupt the animal's sociability, motor skills or sensation. However, in the absence of GABA co-transmission, we found significant alterations in social, spatial and fear memory as well as a reduced reliance on striatum-dependent response strategies in a T-maze. In addition, male conditional knockout (CKO) mice showed increased locomotion. Discussion: Taken together, the loss of GABA co-transmission leads to deficits in higher brain functions and behaviors. Therefore, we propose that ACh/GABA co-transmission modulates neural circuitry involved in the affected behaviors.

Panic disorder aging characteristics: The role of telomerase reverse transcriptase gene and brain function

Panic disorder (PD) causes serious functional damage and disability and accelerates the process of individual aging. The pathological basis of PD is the same as that of age-related diseases, which is proposed as a new viewpoint in recent years. Memory decline and social functional impairment are common manifestations of accelerated aging in PD. The function of telomerase reverse transcriptase (TERT) and telomere length (TL) is abnormal in patients with aging and PD. However, the molecular mechanism behind remains unclear. The purpose of this study was to explore the relationship between TERT gene expression (including DNA methylation) and the changes in PD aging characteristics (memory and social function). By TERT gene knockout mice, we found that loss of TERT attenuated the acquisition of recent fear memory during contextual fear conditioning. This study reported that a significantly lower methylation level of human TERT (hTERT) gene was detected in PD patients compared with healthy control and particularly decreased CpG methylation in the promoter region of hTERT was associated with the clinical characteristics in PD. Regional homogeneity (ReHo) analysis showed that the methylation of hTERT (cg1295648) influenced social function of PD patients through moderating the function of the left postcentral gyrus (PCG). This indicates that the hTERT gene may play an important role in the pathological basis of PD aging and may become a biological marker for evaluating PD aging. These findings provide multidimensional evidence for the underlying genetic and pathological mechanisms of PD.

Deficient DNA base-excision repair in the forebrain leads to a sex-specific anxiety-like phenotype in mice

Background

Neuropsychiatric disorders, such as schizophrenia (SZ) and autism spectrum disorder (ASD), are common, multi-factorial and multi-symptomatic disorders. Ample evidence implicates oxidative stress, deficient repair of oxidative DNA lesions and DNA damage in the development of these disorders. However, it remains unclear whether insufficient DNA repair and resulting DNA damage are causally connected to their aetiopathology, or if increased levels of DNA damage observed in patient tissues merely accumulate as a consequence of cellular dysfunction. To assess a potential causal role for deficient DNA repair in the development of these disorders, we behaviourally characterized a mouse model in which CaMKIIa-Cre-driven postnatal conditional knockout (KO) of the core base-excision repair (BER) protein XRCC1 leads to accumulation of unrepaired DNA damage in the forebrain.

Results

CaMKIIa-Cre expression caused specific deletion of XRCC1 in the dorsal dentate gyrus (DG), CA1 and CA2 and the amygdala and led to increased DNA damage therein. While motor coordination, cognition and social behaviour remained unchanged, XRCC1 KO in the forebrain caused increased anxiety-like behaviour in males, but not females, as assessed by the light–dark box and open field tests. Conversely, in females but not males, XRCC1 KO caused an increase in learned fear-related behaviour in a cued (Pavlovian) fear conditioning test and a contextual fear extinction test. The relative density of the GABA(A) receptor alpha 5 subunit (GABRA5) was reduced in the amygdala and the dorsal CA1 in XRCC1 KO females, whereas male XRCC1 KO animals exhibited a significant reduction of GABRA5 density in the CA3. Finally, assessment of fast-spiking, parvalbumin-positive (PV) GABAergic interneurons revealed a significant increase in the density of PV+ cells in the DG of male XRCC1 KO mice, while females remained unchanged.

Conclusions

Our results suggest that accumulation of unrepaired DNA damage in the forebrain alters the GABAergic neurotransmitter system and causes behavioural deficits in relation to innate and learned anxiety in a sex-dependent manner. Moreover, the data uncover a previously unappreciated connection between BER deficiency, unrepaired DNA damage in the hippocampus and a sex-specific anxiety-like phenotype with implications for the aetiology and therapy of neuropsychiatric disorders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01377-1.

Correlation between reduced telomere length and behavioural and emotional problems in left-behind children in a rural area in China

Evidence shows that being left behind experience (LBE) during childhood may increase the risks of poor psychopathological outcomes. However, it is unclear to what extent the mental health is affected by the LBE. Telomere length (TL), one of the most extensively studied biological markers of cellular ageing, provides a valuable tool for exploring the potential effects of parent-child separation on psychological problems by integrating genetic and environmental factors. In this study, a total of 613 children (mean age = 10.77, SD = 1.92) were recruited from the rural area of Deyang, Sichuan Province, China. We used a self-designed questionnaire to assess LBE, and collected psychopathological outcomes by using the Piers-Harris Children's Self-concept Scale, the Teacher's Report Form 6/18 and the Youth Self-Report 11/18. Terminal restriction fragment analysis was used to measure TL in peripheral blood leukocytes. Analyses revealed that 342 out of 613 participants (55.79%) were Left-behind children. LBE was observed to associated with shorter TL, lower self-esteem, and increased behavioural and emotional problems. The cumulative effects of LBE may be reflected by greater altered telomere homeostasis, decreased self-esteem, and worsened behavioural and emotional problems. The association of the total time of being left behind with self-esteem and behavioural and emotional problems was significantly mediated by altered telomere homeostasis, with estimated effects of 14.19%, 47.95% and 45.13%, respectively. The LBE in childhood, especially prolonged parent-child separation, increases the risk of mental health problems in childhood and adolescence.

Gender Related Changes in Gene Expression Induced by Valproic Acid in A Mouse Model of Autism and the Correction by S-adenosyl Methionine. Does It Explain the Gender Differences in Autistic Like Behavior?

In previous studies we produced autism like behavioral changes in mice by Valproic acid (VPA) with significant differences between genders. S-adenosine methionine (SAM) prevented the autism like behavior in both genders. The expression of 770 genes of pathways involved in neurophysiology and neuropathology was studied in the prefrontal cortex of 60 days old male and female mice using the NanoString nCounter. In females, VPA induced statistically significant changes in the expression of 146 genes; 71 genes were upregulated and 75 downregulated. In males, VPA changed the expression of only 19 genes, 16 were upregulated and 3 downregulated. Eight genes were similarly changed in both genders. When considering only the genes that were changed by at least 50%, VPA changed the expression of 15 genes in females and 3 in males. Only Nts was similarly downregulated in both genders. SAM normalized the expression of most changed genes in both genders. We presume that genes that are involved in autism like behavior in our model were similarly changed in both genders and corrected by SAM. The behavioral and other differences between genders may be related to genes that were differently affected by VPA in males and females and/or differently affected by SAM.

Crmp4-KO Mice as an Animal Model for Investigating Certain Phenotypes of Autism Spectrum Disorders

Previous research has demonstrated that the collapsin response mediator protein (CRMP) family is involved in the formation of neural networks. A recent whole-exome sequencing study identified a de novo variant (S541Y) of collapsin response mediator protein 4 (CRMP4) in a male patient with autism spectrum disorder (ASD). In addition, Crmp4-knockout (KO) mice show some phenotypes similar to those observed in human patients with ASD. For example, compared with wild-type mice, Crmp4-KO mice exhibit impaired social interaction, abnormal sensory sensitivities, broader distribution of activated (c-Fos expressing) neurons, altered dendritic formation, and aberrant patterns of neural gene expressions, most of which have sex differences. This review summarizes current knowledge regarding the role of CRMP4 during brain development and discusses the possible contribution of CRMP4 deficiencies or abnormalities to the pathogenesis of ASD. Crmp4-KO mice represent an appropriate animal model for investigating the mechanisms underlying some ASD phenotypes, such as impaired social behavior, abnormal sensory sensitivities, and sex-based differences, and other neurodevelopmental disorders associated with sensory processing disorders.

Sex-specific Behavioral Features of Rodent Models of Autism Spectrum Disorder

Sex is an important factor in understanding the clinical presentation, management, and developmental trajectory of children with neuropsychiatric disorders. While much is known about the clinical and neurobehavioral profiles of males with neuropsychiatric disorders, surprisingly little is known about females in this respect. Animal models may provide detailed mechanistic information about sex differences in autism spectrum disorder (ASD) in terms of manifestation, disease progression, and development of therapeutic options. This review aims to widen our understanding of the role of sex in autism spectrum disorder, by summarizing and comparing behavioral characteristics of animal models. Our current understanding of how differences emerge in boys and girls with neuropsychiatric disorders is limited: Information derived from animal studies will stimulate future research on the role of biological maturation rates, sex hormones, sex-selective protective (or aggravating) factors and psychosocial factors, which are essential to devise sex precision medicine and to improve diagnostic accuracy. Moreover, there is a strong need of novel strategies to elucidate the major mechanisms leading to sex-specific autism features, as well as novel models or methods to examine these sex differences.

Sex Differences in Psychiatric Disease: A Focus on the Glutamate System

Alterations in glutamate, the primary excitatory neurotransmitter in the brain, are implicated in several psychiatric diseases. Many of these psychiatric diseases display epidemiological sex differences, with either males or females exhibiting different symptoms or disease prevalence. However, little work has considered the interaction of disrupted glutamatergic transmission and sex on disease states. This review describes the clinical and preclinical evidence for these sex differences with a focus on two conditions that are more prevalent in women: Alzheimer's disease and major depressive disorder, and three conditions that are more prevalent in men: schizophrenia, autism spectrum disorder, and attention deficit hyperactivity disorder. These studies reveal sex differences at multiple levels in the glutamate system including metabolic markers, receptor levels, genetic interactions, and therapeutic responses to glutamatergic drugs. Our survey of the current literature revealed a considerable need for more evaluations of sex differences in future studies examining the role of the glutamate system in psychiatric disease. Gaining a more thorough understanding of how sex differences in the glutamate system contribute to psychiatric disease could provide novel avenues for the development of sex-specific pharmacotherapies.

Prenatal and early-life diesel exhaust exposure causes autism-like behavioral changes in mice

Background

Escalating prevalence of autism spectrum disorders (ASD) in recent decades has triggered increasing efforts in understanding roles played by environmental risk factors as a way to address this widespread public health concern. Several epidemiological studies show associations between developmental exposure to traffic-related air pollution and increased ASD risk. In rodent models, a limited number of studies have shown that developmental exposure to ambient ultrafine particulates or diesel exhaust (DE) can result in behavioral phenotypes consistent with mild ASD. We performed a series of experiments to determine whether developmental DE exposure induces ASD-related behaviors in mice.

Results

C57Bl/6J mice were exposed from embryonic day 0 to postnatal day 21 to 250–300 μg/m³ DE or filtered air (FA) as control. Mice exposed developmentally to DE exhibited deficits in all three of the hallmark categories of ASD behavior: reduced social interaction in the reciprocal interaction and social preference tests, increased repetitive behavior in the T-maze and marble-burying test, and reduced or altered communication as assessed by measuring isolation-induced ultrasonic vocalizations and responses to social odors.

Conclusions

These findings demonstrate that exposure to traffic-related air pollution, in particular that associated with diesel-fuel combustion, can cause ASD-related behavioral changes in mice, and raise concern about air pollution as a contributor to the onset of ASD in humans.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0254-4) contains supplementary material, which is available to authorized users.