Antipurinergic therapy corrects the autism-like features in the Fragile X (Fmr1 knockout) mouse model

Dysregulated metabolic pathways associated with air pollution exposure and the risk of autism: Evidence from epidemiological studies

Autism spectrum disorder (ASD) is a developmental disorder with symptoms that range from social and communication impairments to restricted interests and repetitive behavior and is the 4th most disabling condition for children aged 5-14. Risk factors of ASD are not fully understood. Environmental risk factors are believed to play a significant role in the ASD epidemic. Research focusing on air pollution exposure as an early-life risk factor of autism is growing, with numerous studies finding associations of traffic and industrial emissions with an increased risk of ASD. One of the possible mechanisms linking autism and air pollution exposure is metabolic dysfunction. However, there were no consensus about the key metabolic pathways and corresponding metabolite signatures in mothers and children that are altered by air pollution exposure and cause the ASD. Therefore, we performed a review of published papers examining the metabolomic signatures and metabolic pathways that are associated with either air pollution exposure or ASD risk in human studies. In conclusion, we found that dysregulated lipid, fatty acid, amino acid, neurotransmitter, and microbiome metabolisms are associated with both short-term and long-term air pollution exposure and the risk of ASD. These dysregulated metabolisms may provide insights into ASD etiology related to air pollution exposure, particularly during the perinatal period in which neurodevelopment is highly susceptible to damage from oxidative stress and inflammation.

Pannexin1 Mediates Early-Life Seizure-Induced Social Behavior Deficits

There is a high co-morbidity between childhood epilepsy and autism spectrum disorder (ASD), with age of seizure onset being a critical determinant of behavioral outcomes. The interplay between these comorbidities has been investigated in animal models with results showing that the induction of seizures at early post-natal ages leads to learning and memory deficits and to autistic-like behavior in adulthood. Modifications of the excitation/inhibition (glutamate/GABA, ATP/adenosine) balance that follows early-life seizures (ELS) are thought to be the physiological events that underlie neuropsychiatric and neurodevelopmental disorders. Although alterations in purinergic/adenosinergic signaling have been implicated in seizures and ASD, it is unknown whether the ATP release channels, Pannexin1 (Panx1), contribute to ELS-induced behavior changes. To tackle this question, we used the ELS-kainic acid model in transgenic mice with global and cell type specific deletion of Panx1 to evaluate whether these channels were involved in behavioral deficits that occur later in life. Our studies show that ELS results in Panx1 dependent social behavior deficits and also in poor performance in a spatial memory test that does not involve Panx1. These findings provide support for a link between ELS and adult behavioral deficits. Moreover, we identify neuronal and not astrocyte Panx1 as a potential target to specifically limit astrogliosis and social behavioral deficits resultant from early-life seizures.

Human-derived fecal microbiota transplantation alleviates social deficits of the BTBR mouse model of autism through a potential mechanism involving vitamin B6 metabolism

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by social communication deficiencies and stereotypic behaviors influenced by hereditary and/or environmental risk factors. There are currently no approved medications for treating the core symptoms of ASD. Human fecal microbiota transplantation (FMT) has emerged as a potential intervention to improve autistic symptoms, but the underlying mechanisms are not fully understood. In this study, we evaluated the effects of human-derived FMT on behavioral and multi-omics profiles of the BTBR mice, an established model for ASD. FMT effectively alleviated the social deficits in the BTBR mice and normalized their distinct plasma metabolic profile, notably reducing the elevated long-chain acylcarnitines. Integrative analysis linked these phenotypic changes to specific Bacteroides species and vitamin B6 metabolism. Indeed, vitamin B6 supplementation improved the social behaviors in BTBR mice. Collectively, these findings shed new light on the interplay between FMT and vitamin B6 metabolism and revealed a potential mechanism underlying the therapeutic role of FMT in ASD.IMPORTANCEAccumulating evidence supports the beneficial effects of human fecal microbiota transplantation (FMT) on symptoms associated with autism spectrum disorder (ASD). However, the precise mechanism by which FMT induces a shift in the microbiota and leads to symptom improvement remains incompletely understood. This study integrated data from colon-content metagenomics, colon-content metabolomics, and plasma metabolomics to investigate the effects of FMT treatment on the BTBR mouse model for ASD. The analysis linked the amelioration of social deficits following FMT treatment to the restoration of mitochondrial function and the modulation of vitamin B6 metabolism. Bacterial species and compounds with beneficial roles in vitamin B6 metabolism and mitochondrial function may further contribute to improving FMT products and designing novel therapies for ASD treatment.

Metabolic network analysis of pre-ASD newborns and 5-year-old children with autism spectrum disorder

Classical metabolomic and new metabolic network methods were used to study the developmental features of autism spectrum disorder (ASD) in newborns (n = 205) and 5-year-old children (n = 53). Eighty percent of the metabolic impact in ASD was caused by 14 shared biochemical pathways that led to decreased anti-inflammatory and antioxidant defenses, and to increased physiologic stress molecules like lactate, glycerol, cholesterol, and ceramides. CIRCOS plots and a new metabolic network parameter,V ° net, revealed differences in both the kind and degree of network connectivity. Of 50 biochemical pathways and 450 polar and lipid metabolites examined, the developmental regulation of the purine network was most changed. Purine network hub analysis revealed a 17-fold reversal in typically developing children. This purine network reversal did not occur in ASD. These results revealed previously unknown metabolic phenotypes, identified new developmental states of the metabolic correlation network, and underscored the role of mitochondrial functional changes, purine metabolism, and purinergic signaling in autism spectrum disorder.

Pattern glare sensitivity distinguishes subclinical autism and schizotypy

INTRODUCTION

Schizophrenia and autism spectrum disorder are distinct neurodevelopmental disorders sharing clinically relevant behaviours. However, early sensory responses show divergent responses. Individuals with schizophrenia typically exhibit cortical hypo-excitability whereas individuals with autism show cortical hyperexcitability. Identifying reliable neurobiological differences between the disorders can diminish misdiagnosis and optimise treatments.

METHODS

The pattern glare test (PGT) is a simple measure of behavioural hyperexcitability. It measures the number of illusions seen in a static horizontal grating. We collected PGT data from non-clinical adults varying in traits of autism and schizophrenia (schizotypy). 576 undergraduate students completed an online survey consisting of the Schizotypal Personality Questionnaire - Brief Revised, the Autism Spectrum Quotient, and the PGT.

RESULTS

Subclinical autism and schizotypy traits were highly positively correlated. However, only schizotypy scores were significantly predictive of reporting more pattern glare (PG) illusions. When assessing the subcomponents of the schizotypy and autism scores, positive and disorganised schizotypy traits were predictive of reporting more PG illusions. Whereas, subclinical autism factors were not predictive of PG illusions.

CONCLUSIONS

High schizotypy performed the PGT in a manner consistent with behavioural hyperexcitability. The PGT distinguished subclinical autistic traits from schizotypy, suggesting potential clinical application.

Retinal GABAergic Alterations in Adults with Autism Spectrum Disorder

Alterations in γ-aminobutyric acid (GABA) have been implicated in sensory differences in individuals with autism spectrum disorder (ASD). Visual signals are initially processed in the retina, and in this study, we explored the hypotheses that the GABA-dependent retinal response to light is altered in individuals with ASD. Light-adapted electroretinograms were recorded from 61 adults (38 males and 23 females; n = 22 ASD) in response to three stimulus protocols: (1) the standard white flash, (2) the standard 30 Hz flickering protocol, and (3) the photopic negative response protocol. Participants were administered an oral dose of placebo, 15 or 30 mg of arbaclofen (STX209, GABAB agonist) in a randomized, double-blind, crossover order before the test. At baseline (placebo), the a-wave amplitudes in response to single white flashes were more prominent in ASD, relative to typically developed (TD) participants. Arbaclofen was associated with a decrease in the a-wave amplitude in ASD, but an increase in TD, eliminating the group difference observed at baseline. The extent of this arbaclofen-elicited shift significantly correlated with the arbaclofen-elicited shift in cortical responses to auditory stimuli as measured by using an electroencephalogram in our prior study and with broader autistic traits measured with the autism quotient across the whole cohort. Hence, GABA-dependent differences in retinal light processing in ASD appear to be an accessible component of a wider autistic difference in the central processing of sensory information, which may be upstream of more complex autistic phenotypes.

NADPH-oxidases as potential pharmacological targets for thrombosis and depression comorbidity

There is a complex interrelationship between the nervous system and the cardiovascular system. Comorbidities of cardiovascular diseases (CVD) with mental disorders, and vice versa, are prevalent. Adults with mental disorders such as anxiety and depression have a higher risk of developing CVD, and people with CVD have an increased risk of being diagnosed with mental disorders. Oxidative stress is one of the many pathways associated with the pathophysiology of brain and cardiovascular disease. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is one of the major generators of reactive oxygen species (ROS) in mammalian cells, as it is the enzyme that specifically produces superoxide. This review summarizes recent findings on the consequences of NOX activation in thrombosis and depression. It also discusses the therapeutic effects and pharmacological strategies of NOX inhibitors in CVD and brain disorders. A better comprehension of these processes could facilitate the development of new therapeutic approaches for the prevention and treatment of the comorbidity of thrombosis and depression.

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.

Impact of Suramin on Key Pathological Features of Sporadic Alzheimer's Disease-Derived Forebrain Neurons

Background

Alzheimer's disease (AD) is characterized by disrupted proteostasis and macroautophagy (hereafter "autophagy"). The pharmacological agent suramin has known autophagy modulation properties with potential efficacy in mitigating AD neuronal pathology.

Objective

In the present work, we investigate the impact of forebrain neuron exposure to suramin on the Akt/mTOR signaling pathway, a major regulator of autophagy, in comparison with rapamycin and chloroquine. We further investigate the effect of suramin on several AD-related biomarkers in sporadic AD (sAD)-derived forebrain neurons.

Methods

Neurons differentiated from ReNcell neural progenitors were used to assess the impact of suramin on the Akt/mTOR signaling pathway relative to the autophagy inducer rapamycin and autophagy inhibitor chloroquine. Mature forebrain neurons were differentiated from induced pluripotent stem cells (iPSCs) sourced from a late-onset sAD patient and treated with 100μM suramin for 72 h, followed by assessments for amyloid-β, phosphorylated tau, oxidative/nitrosative stress, and synaptic puncta density.

Results

Suramin treatment of sAD-derived neurons partially ameliorated the increased p-Tau(S199)/Tau ratio, and fully remediated the increased glutathione to oxidized nitric oxide ratio, observed in untreated sAD-derived neurons relative to healthy controls. These positive results may be due in part to the distinct increases in Akt/mTOR pathway mediator p-p70S6K noted with suramin treatment of both ReNcell-derived and iPSC-derived neurons. Longer term neuronal markers, such as synaptic puncta density, were unaffected by suramin treatment.

Conclusions

These findings provide initial evidence supporting the potential of suramin to reduce the degree of dysregulation in sAD-derived forebrain neurons in part via the modulation of autophagy.

Metabolic features of treatment-refractory major depressive disorder with suicidal ideation

Peripheral blood metabolomics was used to gain chemical insight into the biology of treatment-refractory Major Depressive Disorder with suicidal ideation, and to identify individualized differences for personalized care. The study cohort consisted of 99 patients with treatment-refractory major depressive disorder and suicidal ideation (trMDD-SI n = 52 females and 47 males) and 94 age- and sex-matched healthy controls (n = 48 females and 46 males). The median age was 29 years (IQR 22-42). Targeted, broad-spectrum metabolomics measured 448 metabolites. Fibroblast growth factor 21 (FGF21) and growth differentiation factor 15 (GDF15) were measured as biomarkers of mitochondrial dysfunction. The diagnostic accuracy of plasma metabolomics was over 90% (95%CI: 0.80-1.0) by area under the receiver operator characteristic (AUROC) curve analysis. Over 55% of the metabolic impact in males and 75% in females came from abnormalities in lipids. Modified purines and pyrimidines from tRNA, rRNA, and mRNA turnover were increased in the trMDD-SI group. FGF21 was increased in both males and females. Increased lactate, glutamate, and saccharopine, and decreased cystine provided evidence of reductive stress. Seventy-five percent of the metabolomic abnormalities found were individualized. Personalized deficiencies in CoQ10, flavin adenine dinucleotide (FAD), citrulline, lutein, carnitine, or folate were found. Pathways regulated by mitochondrial function dominated the metabolic signature. Peripheral blood metabolomics identified mitochondrial dysfunction and reductive stress as common denominators in suicidal ideation associated with treatment-refractory major depressive disorder. Individualized metabolic differences were found that may help with personalized management.

Randomized clinical trial of low dose suramin intravenous infusions for treatment of autism spectrum disorder

BACKGROUND

There is a critical need for effective treatment of the core symptoms of autism spectrum disorder (ASD). The purinergic antagonist suramin may improve core symptoms through restoration of normal mitochondrial function and reduction of neuro-inflammation via its known antagonism of P2X and P2Y receptors. Nonclinical studies in fragile X knockout mice and the maternal immune activation model support these hypotheses.

METHODS

We conducted a 14 week, randomized, double-blind, placebo-controlled proof -of-concept study (N = 52) to test the efficacy and safety of suramin intravenous infusions in boys aged 4-15 years with moderate to severe ASD. The study had 3 treatment arms: 10 mg/kg suramin, 20 mg/kg suramin, and placebo given at baseline, week 4, and week 8. The Aberrant Behavior Checklist of Core Symptoms (ABC-Core) (subscales 2, 3, and 5) was the primary endpoint and the Clinical Global Impressions-Improvement (CGI-I) was a secondary endpoint.

RESULTS

Forty-four subjects completed the study. The 10 mg/kg suramin group showed a greater, but statistically non-significant, numeric improvement (- 12.5 ± 3.18 [mean ± SE]) vs. placebo (- 8.9 ± 2.86) in ABC-Core at Week 14. The 20 mg/kg suramin group did not show improvement over placebo. In exploratory analyses, the 10 mg/kg arm showed greater ABC Core differences from placebo in younger subjects and among those with less severe symptoms. In CGI-I, the 10 mg/kg arm showed a statistically significant improvement from baseline (2.8 ± 0.30 [mean ± SE]) compared to placebo (1.7 ± 0.27) (p = 0.016). The 20 mg/kg arm had a 2.0 ± 0.28 improvement in CGI-I, which was not statistically significant compared to placebo (p = 0.65).

CONCLUSION

Suramin was generally safe and well tolerated over 14 weeks; most adverse events were mild to moderate in severity. Trial Registration Registered with the South African Health Authority, registration number DOH-27-0419-6116.

CLINICALTRIALS

Gov registration ID is NCT06058962, last update posted 2023-09-28.

Pleiotropic contribution of rbfox1 to psychiatric and neurodevelopmental phenotypes in a zebrafish model

RBFOX1 is a highly pleiotropic gene that contributes to several psychiatric and neurodevelopmental disorders. Both rare and common variants in RBFOX1 have been associated with several psychiatric conditions, but the mechanisms underlying the pleiotropic effects of RBFOX1 are not yet understood. Here we found that, in zebrafish, rbfox1 is expressed in spinal cord, mid- and hindbrain during developmental stages. In adults, expression is restricted to specific areas of the brain, including telencephalic and diencephalic regions with an important role in receiving and processing sensory information and in directing behaviour. To investigate the effect of rbfox1 deficiency on behaviour, we used rbfox1sa15940, a rbfox1 loss-of-function line. We found that rbfox1sa15940 mutants present hyperactivity, thigmotaxis, decreased freezing behaviour and altered social behaviour. We repeated these behavioural tests in a second rbfox1 loss-of-function line with a different genetic background, rbfox1del19, and found that rbfox1 deficiency affects behaviour similarly in this line, although there were some differences. rbfox1del19 mutants present similar thigmotaxis, but stronger alterations in social behaviour and lower levels of hyperactivity than rbfox1sa15940 fish. Taken together, these results suggest that rbfox1 deficiency leads to multiple behavioural changes in zebrafish that might be modulated by environmental, epigenetic and genetic background effects, and that resemble phenotypic alterations present in Rbfox1-deficient mice and in patients with different psychiatric conditions. Our study thus highlights the evolutionary conservation of rbfox1 function in behaviour and paves the way to further investigate the mechanisms underlying rbfox1 pleiotropy on the onset of neurodevelopmental and psychiatric disorders.

The Relevance of Animal Models of Social Isolation and Social Motivation for Understanding Schizophrenia: Review and Future Directions

BACKGROUND AND HYPOTHESES

Social dysfunction in schizophrenia includes symptoms of withdrawal and deficits in social skills, social cognition, and social motivation. Based on the course of illness, with social withdrawal occurring prior to psychosis onset, it is likely that the severity of social withdrawal/isolation contributes to schizophrenia neuropathology.

STUDY DESIGN

We review the current literature on social isolation in rodent models and provide a conceptual framework for its relationship to social withdrawal and neural circuit dysfunction in schizophrenia. We next review preclinical tasks of social behavior used in schizophrenia-relevant models and discuss strengths and limitations of existing approaches. Lastly, we consider new effort-based tasks of social motivation and their potential for translational studies in schizophrenia.

STUDY RESULTS

Social isolation rearing in rats produces profound differences in behavior, pharmacologic sensitivity, and neurochemistry compared to socially reared rats. Rodent models relevant to schizophrenia exhibit deficits in social behavior as measured by social interaction and social preference tests. Newer tasks of effort-based social motivation are being developed in rodents to better model social motivation deficits in neuropsychiatric disorders.

CONCLUSIONS

While experimenter-imposed social isolation provides a viable experimental model for understanding some biological mechanisms linking social dysfunction to clinical and neural pathology in schizophrenia, it bypasses critical antecedents to social isolation in schizophrenia, notably deficits in social reward and social motivation. Recent efforts at modeling social motivation using effort-based tasks in rodents have the potential to quantify these antecedents, identify models (eg, developmental, genetic) that produce deficits, and advance pharmacological treatments for social motivation.

Autistic traits and alcohol use in adolescents within the general population

It has been suggested that autistic traits are associated with less frequent alcohol use in adolescence. Our study seeks to examine the relationship between autistic traits and alcohol use in a large adolescent population. Leveraging data from the IMAGEN cohort, including 2045 14-year-old adolescents that were followed-up to age 18, we selected items on social preference/skills and rigidity from different questionnaires. We used linear regression models to (1) test the effect of the sum scores on the prevalence of alcohol use (AUDIT-C) over time, (2) explore the relationship between autistic traits and alcohol use patterns, and (3) explore the specific effect of each autistic trait on alcohol use. Higher scores on the selected items were associated with trajectories of less alcohol use from the ages between 14 and 18 (b = - 0.030; CI 95% = - 0.042, - 0.017; p < 0.001). Among adolescents who used alcohol, those who reported more autistic traits were also drinking less per occasion than their peers and were less likely to engage in binge drinking. We found significant associations between alcohol use and social preference (p < 0.001), nervousness for new situations (p = 0.001), and detail orientation (p < 0.001). Autistic traits (social impairment, detail orientation, and anxiety) may buffer against alcohol use in adolescence.

Alterations of Purinergic Receptors Levels and Their Involvement in the Glial Cell Morphology in a Pre-Clinical Model of Autism Spectrum Disorders

Recent data suggest that defects in purinergic signalling are a common denominator of autism spectrum disorders (ASDs), though nothing is known about whether the disorder-related imbalance occurs at the receptor level. In this study, we investigated whether prenatal exposure to valproic acid (VPA) induces changes in purinergic receptor expression in adolescence and whether it corresponds to glial cell activation. Pregnant dams were subjected to an intraperitoneal injection of VPA at embryonic day 12.5. In the hippocampi of adolescent male VPA offspring, we observed an increase in the level of P2X1, with concomitant decreases in P2X7 and P2Y1 receptors. In contrast, in the cortex, the level of P2X1 was significantly reduced. Also, significant increases in cortical P2Y1 and P2Y12 receptors were detected. Additionally, we observed profound alterations in microglial cell numbers and morphology in the cortex of VPA animals, leading to the elevation of pro-inflammatory cytokine expression. The changes in glial cells were partially reduced via a single administration of a non-selective P2 receptor antagonist. These studies show the involvement of purinergic signalling imbalance in the modulation of brain inflammatory response induced via prenatal VPA exposure and may indicate that purinergic receptors are a novel target for pharmacological intervention in ASDs.

Sex-specific microglia state in the Neuroligin-4 knock-out mouse model of autism spectrum disorder

Neuroligin-4 (NLGN4) loss-of-function mutations are associated with monogenic heritable autism spectrum disorder (ASD) and cause alterations in both synaptic and behavioral phenotypes. Microglia, the resident CNS macrophages, are implicated in ASD development and progression. Here we studied the impact of NLGN4 loss in a mouse model, focusing on microglia phenotype and function in both male and female mice. NLGN4 depletion caused lower microglia density, less ramified morphology, reduced response to injury and purinergic signaling specifically in the hippocampal CA3 region predominantly in male mice. Proteomic analysis revealed disrupted energy metabolism in male microglia and provided further evidence for sexual dimorphism in the ASD associated microglial phenotype. In addition, we observed impaired gamma oscillations in a sex-dependent manner. Lastly, estradiol application in male NLGN4-/- mice restored the altered microglial phenotype and function. Together, these results indicate that loss of NLGN4 affects not only neuronal network activity, but also changes the microglia state in a sex-dependent manner that could be targeted by estradiol treatment.

People with higher autistic traits show stronger binding for color-shape associations

Non-synesthetes exhibit a tendency to associate specific shapes with particular colors (i.e., circle-red, triangle-yellow, and square-blue). Such color-shape associations (CSAs) could potentially affect the feature binding of colors and shapes, thus resulting in people reporting more binding errors in the case of incongruent, rather than congruent, colored-shape pairs. Individuals with autism spectrum disorder (ASD) exhibit atypical sensory processing and impaired multisensory integration. Here, we examined whether autistic traits (Autism-Spectrum Quotient; AQ) influence the strength of color-shape associations, as evidenced by the occurrence of binding errors in incongruent minus congruent conditions. Participants took part in an experiment designed to reveal binding errors induced by incongruent and congruent colored-shape pairs, and completed the Japanese version of the AQ score. The results revealed a significant correlation between AQ scores and occurrence of binding errors when participants were presented with the circle-red and triangle-yellow CSAs: That is, individuals with higher autistic traits tend to make more binding errors in incongruent minus congruent colored-shape pairs, indicating a stronger binding of circle-red and triangle-yellow associations. These results therefore suggest that autistic traits play a role in forming color-shape associations, shedding light on the nature of both color-shape associations and autistic perception.

Altered Purinergic Signaling in Neurodevelopmental Disorders: Focus on P2 Receptors

With the umbrella term 'neurodevelopmental disorders' (NDDs) we refer to a plethora of congenital pathological conditions generally connected with cognitive, social behavior, and sensory/motor alterations. Among the possible causes, gestational and perinatal insults have been demonstrated to interfere with the physiological processes necessary for the proper development of fetal brain cytoarchitecture and functionality. In recent years, several genetic disorders caused by mutations in key enzymes involved in purine metabolism have been associated with autism-like behavioral outcomes. Further analysis revealed dysregulated purine and pyrimidine levels in the biofluids of subjects with other NDDs. Moreover, the pharmacological blockade of specific purinergic pathways reversed the cognitive and behavioral defects caused by maternal immune activation, a validated and now extensively used rodent model for NDDs. Furthermore, Fragile X and Rett syndrome transgenic animal models as well as models of premature birth, have been successfully utilized to investigate purinergic signaling as a potential pharmacological target for these diseases. In this review, we examine results on the role of the P2 receptor signaling in the etiopathogenesis of NDDs. On this basis, we discuss how this evidence could be exploited to develop more receptor-specific ligands for future therapeutic interventions and novel prognostic markers for the early detection of these conditions.

P2 receptor-mediated signaling in the physiological and pathological brain: From development to aging and disease

The purinergic pathway mediates both pro-inflammatory and anti-inflammatory responses, whereas the breakdown of adenosine triphosphate (ATP) is in a critical equilibrium. Under physiological conditions, extracellular ATP is maintained at a nanomolar concentration. Whether released into the medium following tissue damage, inflammation, or hypoxia, ATP is considered a clear indicator of cell damage and a marker of pathological conditions. In this overview, we provide an update on the participation of P2 receptor-mediated purinergic signaling in normal and pathological brain development, with special emphasis on neurodevelopmental psychiatric disorders. Since purinergic signaling is ubiquitous, it is not surprising that it plays a prominent role in developmental processes and pathological alterations. The main aim of this review is to conceptualize the time-dependent dynamic changes in the participation of different players in the purinome in shaping the normal and aberrant developmental patterns and diseases of the central nervous system over one's lifespan.

Proteome profiling of the prefrontal cortex of Fmr1 knockout mouse reveals enhancement of complement and coagulation cascades

Fragile X mental retardation protein (FMRP) deficit resulted from mutations in its encoded fragile X mental retardation 1 (Fmr1) gene is a common inherited cause of Fragile X syndrome (FXS) characterized by intellectual disability and autism spectrum disorder (ASD). The FMRP absence-induced altered gene expression in prefrontal cortex (PFC) are associated with autistic behaviors. However, there lacks a large-scale protein profiling in the PFC upon loss of FMRP. This study used a TMT-labeled proteomic analysis to identify a protein profile of the PFC in the Fmr1 knockout mouse. A total of 5886 proteins were identified in the PFC with 100 differentially abundant proteins (DAPs) in response to FMRP deficiency. Bioinformatical analyses showed that these DAPs were mostly enriched in immune system, extracellular part and complement and coagulation cascades. The complement and coagulation cascades include 6 upregulated proteins (SERPING1, C1QA, C3, FGA, FGB and FGG), which are associated with fibrin degradation, cell lysis, degranulation chemotaxis and phagocytosis linked to activation of immune and inflammatory responses. Thus, our data provide an altered protein profile upon loss of FMRP in the PFC, and suggest that the enhancement of complement and coagulation cascades might contribute to etiological and pathogenic roles of ASD in FXS. SIGNIFICANCE: The etiology of autism spectrum disorder (ASD), a group of neurobiological disorders characterized by deficits in social interaction barriers and other abnormal behaviors, is still elusive. Autistic-like phenotypes are present in both Fragile X syndrome (FXS) patients and FMRP-deficiency FXS models. Given that prefrontal cortex is a critical brain area for social interaction, the FMRP absence induced-changes of a subset of proteins might contribute to ASD in FXS. Using a comprehensive proteomic analysis, this study provides a prefrontal protein profile of the FMRP-absent mouse with a total of 100 differentially abundant proteins (DAPs). Bioinformatic analyses suggest that these DAPs are mainly involved in the regulations of immune system and complement and coagulation cascades. We also show that 6 upregulated proteins (SERPING1, C1QA, C3, FGA, FGB and FGG) in the complement and coagulation cascades are associated with fibrin degradation, cell lysis, degranulation chemotaxis and phagocytosis regarding dysregulation of immune and inflammatory responses in the prefrontal cortex. Therefore, this study suggests that these FMRP-deficient DAPs in the prefrontal cortex might contribute to the etiology and pathogenesis of ASD in FXS.

Investigation of autism-related transcription factors underlying sex differences in the effects of bisphenol A on transcriptome profiles and synaptogenesis in the offspring hippocampus

BACKGROUND

Bisphenol A (BPA) has been linked to susceptibility to autism spectrum disorder (ASD). Our recent studies have shown that prenatal BPA exposure disrupted ASD-related gene expression in the hippocampus, neurological functions, and behaviors associated with ASD in a sex-specific pattern. However, the molecular mechanisms underlying the effects of BPA are still unclear.

METHODS

Transcriptome data mining and molecular docking analyses were performed to identify ASD-related transcription factors (TFs) and their target genes underlying the sex-specific effects of prenatal BPA exposure. Gene ontology analysis was conducted to predict biological functions associated with these genes. The expression levels of ASD-related TFs and targets in the hippocampus of rat pups prenatally exposed to BPA were measured using qRT-PCR analysis. The role of the androgen receptor (AR) in BPA-mediated regulation of ASD candidate genes was investigated using a human neuronal cell line stably transfected with AR-expression or control plasmid. Synaptogenesis, which is a function associated with genes transcriptionally regulated by ASD-related TFs, was assessed using primary hippocampal neurons isolated from male and female rat pups prenatally exposed to BPA.

RESULTS

We found that there was a sex difference in ASD-related TFs underlying the effects of prenatal BPA exposure on the transcriptome profiles of the offspring hippocampus. In addition to the known BPA targets AR and ESR1, BPA could directly interact with novel targets (i.e., KDM5B, SMAD4, and TCF7L2). The targets of these TFs were also associated with ASD. Prenatal BPA exposure disrupted the expression of ASD-related TFs and targets in the offspring hippocampus in a sex-dependent manner. Moreover, AR was involved in the BPA-mediated dysregulation of AUTS2, KMT2C, and SMARCC2. Prenatal BPA exposure altered synaptogenesis by increasing synaptic protein levels in males but not in females, but the number of excitatory synapses was increased in female primary neurons only.

CONCLUSIONS

Our findings suggest that AR and other ASD-related TFs are involved in sex differences in the effects of prenatal BPA exposure on transcriptome profiles and synaptogenesis in the offspring hippocampus. These TFs may play an essential role in an increased ASD susceptibility associated with endocrine-disrupting chemicals, particularly BPA, and the male bias of ASD.

Mouse models of fragile X-related disorders

The fragile X-related disorders are an important group of hereditary disorders that are caused by expanded CGG repeats in the 5' untranslated region of the FMR1 gene or by mutations in the coding sequence of this gene. Two categories of pathological CGG repeats are associated with these disorders, full mutation alleles and shorter premutation alleles. Individuals with full mutation alleles develop fragile X syndrome, which causes autism and intellectual disability, whereas those with premutation alleles, which have shorter CGG expansions, can develop fragile X-associated tremor/ataxia syndrome, a progressive neurodegenerative disease. Thus, fragile X-related disorders can manifest as neurodegenerative or neurodevelopmental disorders, depending on the size of the repeat expansion. Here, we review mouse models of fragile X-related disorders and discuss how they have informed our understanding of neurodegenerative and neurodevelopmental disorders. We also assess the translational value of these models for developing rational targeted therapies for intellectual disability and autism disorders.

To What Extent is the Contribution of Language to Learning via Instructions Modulated by the Expression of Autism Traits?

Language plays a fundamental role in enabling flexible, goal-directed behaviour. This study investigated whether the contribution of language to instruction encoding is modulated by the expression of autism traits, as measured by the Autism Spectrum Quotient (ASQ) questionnaire. Participants (N = 108) completed six choice reaction time tasks, with each task consisting of six stimulus-response mappings. During an instruction phase preceding each task, participants performed either a verbal, non-verbal or no distractor task. Participants made more errors in the verbal distractor task condition, but this detrimental effect did not differ significantly between the high (top 33%) and low (bottom 33%) ASQ groups. Hence, the contribution of language to instruction encoding does not appear to be modulated by the expression of autism traits.

Effects of Stromal Cell Conditioned Medium and Antipurinergic Treatment on Macrophage Phenotype

The immunomodulatory capacity of the human mesenchymal stromal cell (MSC) secretome has been a critical driver for the development of cell-free MSC products, such as conditioned medium (CM), for regenerative medicine applications. This is particularly true as cell-free MSC products present several advantages over direct autologous or allogeneic MSC delivery with respect to safety, manufacturability, and defined potency. Recently, significant effort has been placed into creating novel MSC CM formulations with an immunomodulatory capacity tailored for specific regenerative contexts. For instance, the immunoregulatory nature of MSC CM has previously been tuned through a number of cytokine-priming strategies. Herein, we propose an alternate method to tailor the immunomodulatory "phenotype" of cytokine-primed MSC CM through coupling with the pharmacological agent, suramin. Suramin interferes with the signaling of purines including extracellular adenosine triphosphate (ATP), which plays a critical role in the activation of the innate immune system after injury. Toward this end, human THP-1-derived macrophages were activated to a proinflammatory phenotype and treated with (1) unprimed/native MSC CM, (2) interferon-γ/tumor necrosis factor α-primed MSC CM (primed CM), (3) suramin alone, or (4) primed MSC CM and suramin (primed CM/suramin). Markers of key macrophage functions-cytokine secretion, autophagy, oxidative stress modulation, and activation/migration-were assessed. Consistent with previous literature, primed CM elevated macrophage secretion of several proinflammatory and pleiotropic cytokines relative to native CM; whereas addition of suramin imparted consistent shifts in terms of TNFα (↓), interleukin-10 (↓), and hepatocyte growth factor (↑) irrespective of CM. In addition, both primed CM and suramin, individually and combined, increased reactive oxygen species production relative to native CM, and addition of suramin to primed CM shifted levels of CX3CL1, a factor involved in ATP-associated macrophage regulation. Varimax rotation assessment of the secreted cytokine profiles confirmed that primed CM/suramin resulted in a THP-1 phenotypic shift away from the lipopolysaccharide-activated proinflammatory state that was distinct from that of primed CM or native CM alone. This altered primed CM/suramin-associated phenotype may prove beneficial for healing in certain regenerative contexts. These results may inform future work coupling antipurinergic treatments with MSC-derived therapies in regenerative medicine applications.

An RCT study showing few weeks of music lessons enhance audio-visual temporal processing

Music involves different senses and is emotional in nature, and musicians show enhanced detection of audio-visual temporal discrepancies and emotion recognition compared to non-musicians. However, whether musical training produces these enhanced abilities or if they are innate within musicians remains unclear. Thirty-one adult participants were randomly assigned to a music training, music listening, or control group who all completed a one-hour session per week for 11 weeks. The music training group received piano training, the music listening group listened to the same music, and the control group did their homework. Measures of audio-visual temporal discrepancy, facial expression recognition, autistic traits, depression, anxiety, stress and mood were completed and compared from the beginning to end of training. ANOVA results revealed that only the music training group showed a significant improvement in detection of audio-visual temporal discrepancies compared to the other groups for both stimuli (flash-beep and face-voice). However, music training did not improve emotion recognition from facial expressions compared to the control group, while it did reduce the levels of depression, stress and anxiety compared to baseline. This RCT study provides the first evidence of a causal effect of music training on improved audio-visual perception that goes beyond the music domain.

A Possible Causal Involvement of Neuroinflammatory, Purinergic P2X7 Receptors in Psychiatric Disorders

P2X7 receptors (Rs) are prominent members of the P2XR family, which after binding ATP, open non-selective cationic channels, thereby allowing the transmembrane passage of Na+, Ca²⁺, and K+. Long-lasting and repetitive stimulation of the receptor by its agonist leads to the formation of large membrane pores permeable for organic cations of up to 900 Da molecular size. These pores are believed to play a role in apoptosis and inflammation. P2X7Rs are located primarily at peripheral macrophages and microglial cells, the resident macrophages of the CNS. The coactivation of toll-like receptors 4 (TLR4) by lipopolysaccharide, a constituent of the cell membrane of gram-negative bacteria, and the P2X7R by ATP leads to the generation and release of the proinflammatory cytokines interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α. Together with the microglial release of chemokines, reactive oxygen and nitrogen species, proteases, and excitotoxic glutamate, these cytokines result in neurodegeneration. P2X7Rs were found not only to amplify various neurodegenerative illnesses, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis, but also to participate in a range of psychiatric diseases, such as major depression, bipolar disorder, schizophrenia, and autism spectrum disorder. Based on the prevention/reversal of neuroinflammation, pharmacological antagonists of P2X7Rs and their genetic deletion in animal experiments counteract these deleterious psychiatric conditions. Hence, brain penetrant P2X7R antagonists are potential therapeutics for psychiatric diseases, although the available evidence still needs to be extended and validated by further clinical data.

Retinoic Acid Supplementation Rescues the Social Deficits in Fmr1 Knockout Mice

Autism spectrum disorder (ASD) is a heritable neurodevelopmental disorder with the underlying etiology yet incompletely understood and no cure treatment. Patients of fragile X syndrome (FXS) also manifest symptoms, e.g. deficits in social behaviors, that are core traits with ASD. Several studies demonstrated that a mutual defect in retinoic acid (RA) signaling was observed in FXS and ASD. However, it is still unknown whether RA replenishment could pose a positive effect on autistic-like behaviors in FXS. Herein, we found that RA signaling was indeed down-regulated when the expression of FMR1 was impaired in SH-SY5Y cells. Furthermore, RA supplementation rescued the atypical social novelty behavior, but failed to alleviate the defects in sociability behavior or hyperactivity, in Fmr1 knock-out (KO) mouse model. The repetitive behavior and motor coordination appeared to be normal. The RNA sequencing results of the prefrontal cortex in Fmr1 KO mice indicated that deregulated expression of Foxp2, Tnfsf10, Lepr and other neuronal genes was restored to normal after RA treatment. Gene ontology terms of metabolic processes, extracellular matrix organization and behavioral pathways were enriched. Our findings provided a potential therapeutic intervention for social novelty defects in FXS.

Translational validity and methodological underreporting in animal research: A systematic review and meta-analysis of the Fragile X syndrome (Fmr1 KO) rodent model

Predictive models are essential for advancing knowledge of brain disorders. High variation in study outcomes hampers progress. To address the validity of predictive models, we performed a systematic review and meta-analysis on behavioural phenotypes of the knock-out rodent model for Fragile X syndrome according to the PRISMA reporting guidelines. In addition, factors accountable for the heterogeneity between findings were analyzed. The knock-out model showed good translational validity and replicability for hyperactivity, cognitive and seizure phenotypes. Despite low replicability, translational validity was also found for social behaviour and sensory sensitivity, but not for attention, aggression and cognitive flexibility. Anxiety, acoustic startle and prepulse inhibition phenotypes, despite low replicability, were opposite to patient symptomatology. Subgroup analyses for experimental factors moderately explain the low replicability, these analyses were hindered by under-reporting of methodologies and environmental conditions. Together, the model has translational validity for most clinical phenotypes, but caution must be taken due to low effect sizes and high inter-study variability. These findings should be considered in view of other rodent models in preclinical research.

Reading the mind in cartoon eyes: Comparing human versus cartoon emotion recognition in those with high and low levels of autistic traits

People who have a high degree of autistic traits often underperform on theory of mind tasks such as perspective-taking or facial emotion recognition compared to those with lower levels of autistic traits. However, some research suggests that this may not be the case if the agent they are evaluating is anthropomorphic (i.e. animal or cartoon) rather than typically human. The present studies examined the relation between facial emotion recognition and autistic trait profiles in over 750 adults using either a standard or cartoon version of the Reading the Mind in the Eyes (RME) test. Results showed that those scoring above the clinical cut off for autistic traits on the Autism Quotient performed significantly worse than those with the lowest levels of autistic traits on the standard RME, while scores across these groups did not differ substantially on the cartoon version of the task. These findings add further evidence that theory of mind ability such as facial emotion recognition is not at a global deficit in those with a high degree of autistic traits. Instead, differences in this ability may be specific to evaluating human agents.

Altered inflammatory response in FMRP-deficient microglia

Fragile X syndrome (FXS) is an inherited intellectual disability with a high risk for comorbid autism spectrum disorders. Since FXS is a genetic disease, patients are more susceptible to environmental factors aggravating symptomatology. However, this confounding interaction between FXS environmental and genetic risk factors is under-investigated. Here, Fmr1 knock-out (KO) mice and the immune stimulus lipopolysaccharide (LPS) were used to explore this interaction between FXS development and inflammation in microglia, the brain’s primary immune cell. Our results demonstrate that Fmr1 KO and wild-type (WT) microglia are not different in inflammatory outcomes without LPS. However, Fmr1 KO microglia produces an elevated pro-inflammatory and phagocytic response following LPS treatment when compared to WT microglia. Our experiments also revealed baseline differences in mitochondrial function and morphology between WT and Fmr1 KO microglia, which LPS treatment exaggerated. Our data suggest an altered inflammatory mechanism in Fmr1 KO microglia implicating a gene and environment interaction.

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Fmr1 KO microglia display elevated LPS-induced pro-inflammatory gene expressions

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Fmr1 KO microglia display elevated LPS-induced pro-inflammatory cytokine releases

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Fmr1 KO microglia demonstrate increased LPS-induced phagocytic responses

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Fmr1 KO microglial mitochondria have altered properties and LPS-stimulated responses

Profiles of urine and blood metabolomics in autism spectrum disorders

Early diagnosis and treatment for autism spectrum disorder (ASD) pose challenges. The current diagnostic approach for ASD is mainly clinical assessment of patient behaviors. Biomarkers-based identification of ASD would be useful for pediatricians. Currently, there is no specific treatment for ASD, and evidence for the efficacy of alternative treatments remains inconclusive. The prevalence of ASD is increasing, and it is becoming more urgent to find the pathogenesis of such disorder. Metabolomic studies have been used to deeply investigate the alteration of metabolic pathways, including those associated with ASD. Metabolomics is a promising tool for identifying potential biomarkers and possible pathogenesis of ASD. This review comprehensively summarizes and discusses the abnormal metabolic pathways in ASD children, as indicated by evidence from metabolomic studies in urine and blood. In addition, the targeted interventions that could correct the metabolomic profiles relating to the improvement of autistic behaviors in affected animals and humans have been included. The results revealed that the possible underlying pathophysiology of ASD were alterations of amino acids, reactive oxidative stress, neurotransmitters, and microbiota-gut-brain axis. The potential common pathways shared by animal and human studies related to the improvement of ASD symptoms after pharmacological interventions were mammalian-microbial co-metabolite, purine metabolism, and fatty acid oxidation. The content of this review may contribute to novel biomarkers for the early diagnosis of ASD and possible therapeutic paradigms.

TDP-43 and Inflammation: Implications for Amyotrophic Lateral Sclerosis and Frontotemporal Dementia

The abnormal mislocalisation and ubiquitinated protein aggregation of the TAR DNA binding protein 43 (TDP-43) within the cytoplasm of neurons and glia in the central nervous system (CNS) is a pathological hallmark of early-onset neurodegenerative disorders amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The pathomechanisms underlying abnormal mislocalisation and aggregation of TDP-43 remain unknown. However, there is a growing body of evidence implicating neuroinflammation and immune-mediated mechanisms in the pathogenesis of neurodegeneration. Importantly, most of the evidence for an active role of immunity and inflammation in the pathogenesis of ALS and FTD relates specifically to TDP-43, posing the question as to whether immune-mediated mechanisms could hold the key to understanding TDP-43’s underlying role in neurodegeneration in both diseases. Therefore, this review aims to piece together key lines of evidence for the specific association of TDP-43 with key immune and inflammatory pathways to explore the nature of this relationship and the implications for potential pathomechanisms underlying neurodegeneration in ALS and FTD.

Alexithymic But Not Autistic Traits Impair Prosocial Behavior

Social impairments are a core feature of autism-spectrum disorders. However, there is a considerable variability in these impairments. Most autistic individuals show large impairments in social functioning but some autistic individuals show small impairments in social functioning. The variability of these impairments has been attributed to the presence or absence of alexithymia. To address this issue, we capitalized on the fact that alexithymic and autistic traits are broadly distributed in the population. This allowed us to investigate how alexithymic and autistic traits affect social functioning in healthy individuals. Healthy individuals showed impairments on a resource-allocation task that were due to alexithymic but not autistic traits. These findings suggest that alexithymic rather than autistic traits impair prosocial behavior across the autism-spectrum.

Differences Between Autistic and Non-Autistic Adults in the Recognition of Anger from Facial Motion Remain after Controlling for Alexithymia

To date, studies have not established whether autistic and non-autistic individuals differ in emotion recognition from facial motion cues when matched in terms of alexithymia. Here, autistic and non-autistic adults (N = 60) matched on age, gender, non-verbal reasoning ability and alexithymia, completed an emotion recognition task, which employed dynamic point light displays of emotional facial expressions manipulated in terms of speed and spatial exaggeration. Autistic participants exhibited significantly lower accuracy for angry, but not happy or sad, facial motion with unmanipulated speed and spatial exaggeration. Autistic, and not alexithymic, traits were predictive of accuracy for angry facial motion with unmanipulated speed and spatial exaggeration. Alexithymic traits, in contrast, were predictive of the magnitude of both correct and incorrect emotion ratings.

Metabolomic and lipidomic characterization of an X-chromosome deletion disorder in neural progenitor cells by UHPLC-HRMS

INTRODUCTION

Intellectual disorders involving deletions of the X chromosome present a difficult task in the determination of a connection between symptoms and metabolites that could lead to treatment options. One specific disorder of X-chromosomal deletion, Fragile X syndrome, is the most frequently occurring of intellectual disabilities. Previous metabolomic studies have been limited to mouse models that may not have sufficiently revealed the full biochemical diversity of the disease in humans.

OBJECTIVES

The primary objective of this study was to elucidate the human biochemistry in X-chromosomal deletion disorders through metabolomic and lipidomic profiling, using cells from a X-deletion patient as a representative case.

METHODS

Metabolomic and lipidomic analysis was performed by UHPLC-HRMS on neural progenitor (NP) cells isolated from an afflicted female patient versus normal neural progenitor cells.

RESULTS

Results showed perturbations in several metabolic pathways, including those of arginine and proline, that significantly impact both neurotransmitter generation and overall brain function. Coincidently, dysregulation was observed for lipids involved in both cellular structure and membrane integrity. The trends of observed metabolomic changes, as well as lipidomic profiling from identified features, are discussed.

CONCLUSION

The lipidomic and metabolomic profiles of NP cell samples exhibited significant differentiation associated with partial deletion of the X chromosome. These findings suggest that rare X-chromosomal deletion disorders are not only a mental disorder limited to alterations in local neuronal functions, but are also metabolic diseases.

Metabolic and behavioral features of acute hyperpurinergia and the maternal immune activation mouse model of autism spectrum disorder

Since 2012, studies in mice, rats, and humans have suggested that abnormalities in purinergic signaling may be a final common pathway for many genetic and environmental causes of autism spectrum disorder (ASD). The current study in mice was conducted to characterize the bioenergetic, metabolomic, breathomic, and behavioral features of acute hyperpurinergia triggered by systemic injection of the purinergic agonist and danger signal, extracellular ATP (eATP). Responses were studied in C57BL/6J mice in the maternal immune activation (MIA) model and controls. Basal metabolic rates and locomotor activity were measured in CLAMS cages. Plasma metabolomics measured 401 metabolites. Breathomics measured 98 volatile organic compounds. Intraperitoneal eATP dropped basal metabolic rate measured by whole body oxygen consumption by 74% ± 6% (mean ± SEM) and rectal temperature by 6.2˚ ± 0.3˚C in 30 minutes. Over 200 metabolites from 37 different biochemical pathways where changed. Breathomics showed an increase in exhaled carbon monoxide, dimethylsulfide, and isoprene. Metabolomics revealed an acute increase in lactate, citrate, purines, urea, dopamine, eicosanoids, microbiome metabolites, oxidized glutathione, thiamine, niacinamide, and pyridoxic acid, and decreased folate-methylation-1-carbon intermediates, amino acids, short and medium chain acyl-carnitines, phospholipids, ceramides, sphingomyelins, cholesterol, bile acids, and vitamin D similar to some children with ASD. MIA animals were hypersensitive to postnatal exposure to eATP or poly(IC), which produced a rebound increase in body temperature that lasted several weeks before returning to baseline. Acute hyperpurinergia produced metabolic and behavioral changes in mice. The behaviors and metabolic changes produced by ATP injection were associated with mitochondrial functional changes that were profound but reversible.

Neural Mechanisms Underlying Repetitive Behaviors in Rodent Models of Autism Spectrum Disorders

Autism spectrum disorder (ASD) is comprised of several conditions characterized by alterations in social interaction, communication, and repetitive behaviors. Genetic and environmental factors contribute to the heterogeneous development of ASD behaviors. Several rodent models display ASD-like phenotypes, including repetitive behaviors. In this review article, we discuss the potential neural mechanisms involved in repetitive behaviors in rodent models of ASD and related neuropsychiatric disorders. We review signaling pathways, neural circuits, and anatomical alterations in rodent models that display robust stereotypic behaviors. Understanding the mechanisms and circuit alterations underlying repetitive behaviors in rodent models of ASD will inform translational research and provide useful insight into therapeutic strategies for the treatment of repetitive behaviors in ASD and other neuropsychiatric disorders.

Testing the Latent Structure of the Autism Spectrum Quotient in a Sub-clinical Sample of University Students Using Factor Mixture Modelling

In the present study, factor mixture models (FMMs) were used to examine the latent structure underlying the Autism-Spectrum Quotient (AQ) among a sample of 633 undergraduate students. FMM represents a combination of latent-class, person-centered approaches and common-factor, variable-centered approaches to modeling population heterogeneity. Findings suggest the presence of either two or six latent classes with distinct profiles across the set of 50 AQ items. In addition, within each class, individuals can be further differentiated according to their scores on five latent factors. These results suggest the presence of phenotypical heterogeneity at the sub-clinical level in addition to that which is known to exist at the clinical level.

Chronic nicotine, but not suramin or resveratrol, partially remediates the mania-like profile of dopamine transporter knockdown mice

Bipolar disorder (BD) is a severe mental illness affecting 2% of the global population. Current pharmacotherapies provide incomplete symptom remediation, highlighting the need for novel therapeutics. BD is characterized by fluctuations between mania and depression, likely driven by shifts between hyperdopaminergia and hypercholinergia, respectively. Hyperdopaminergia may result from insufficient activity of the dopamine transporter (DAT), the primary mediator of synaptic dopamine clearance. The DAT knockdown (DAT KD) mouse recreates this mechanism and exhibits a highly reproducible hyperexploratory profile in the cross-species translatable Behavioral Pattern Monitor (BPM) that is: (a) consistent with that observed in BD mania patients; and (b) partially normalized by chronic lithium and valproate treatment. The DAT KD/BPM model of mania therefore exhibits high levels of face-, construct-, and predictive-validity for the pre-clinical assessment of putative anti-mania drugs. Three different drug regimens - chronic nicotine (nicotinic acetylcholine receptor (nAChR) agonist; 40 mg/kg/d, 26 d), subchronic suramin (anti-purinergic; 20 mg/kg, 1 × /wk, 4 wks), and subchronic resveratrol (striatal DAT upregulator; 20 mg/kg/d, 4 d) - were administered to separate cohorts of male and female DAT KD- and wildtype (WT) littermate mice, and exploration was assessed in the BPM. Throughout, DAT KD mice exhibited robust hyperexploratory profiles relative to WTs. Nicotine partially normalized this behavior. Resveratrol modestly upregulated DAT expression but did not normalize DAT KD behavior. These results support the mania-like profile of DAT KD mice, which may be partially remediated by nAChR agonists via restoration of disrupted catecholaminergic/cholinergic equilibrium. Delineating the precise mechanism of action of nicotine could identify more selective therapeutic targets.

Immune Modulatory Treatments for Autism Spectrum Disorder

Several lines of evidence from family history studies, immunogenetics, maternal immune activation, neuroinflammation, and systemic inflammation support an immune subtype of autism spectrum disorder (ASD). Current Food and Drug Administration-approved medications for ASD do not address the underlying pathophysiology of ASD, have not consistently been shown to address the core symptoms of ASD, and are currently only approved for treating irritability in children and adolescents. In this article, we review the immune modulatory effects of the 2 currently Food and Drug Administration-approved treatments for ASD. We then provide an overview of current data on emerging treatments for ASD from multiple fields of medicine with immune modulatory effects. Although further research is needed to more clearly establish the efficacy and safety of immune modulatory treatments, early data on repurposing medications used to treat systemic inflammation for ASD demonstrate potential benefit and further research is warranted.

Pannexin 1 Regulates Dendritic Protrusion Dynamics in Immature Cortical Neurons

The integration of neurons into networks relies on the formation of dendritic spines. These specialized structures arise from dynamic filopodia-like dendritic protrusions. It was recently reported that cortical neurons lacking the channel protein pannexin 1 (PANX1) exhibited higher dendritic spine densities. Here, we expanded on those findings to investigate, at an earlier developmental time point (with more abundant dendritic protrusions), whether differences in the properties of dendritic protrusion dynamics could contribute to this previously discovered phenomenon. Using a fluorescent membrane tag (mCherry-CD9-10) to visualize dendritic protrusions in developing neurons [at 10 d in vitro (DIV10)], we confirmed that lack of PANX1 led to higher protrusion density, while transient transfection of Panx1 led to decreased protrusion density. To quantify the impact of PANX1 expression on protrusion formation, elimination, and motility, we used live cell imaging in DIV10 neurons (one frame every 5 s for 10 min). We discovered that at DIV10, loss of PANX1 stabilized protrusions. Notably, re-expression of PANX1 in Panx1 knock-out (KO) neurons resulted in a significant increase in protrusion motility and turnover. In summary, these new data revealed that PANX1 could regulate the development of dendritic spines, in part, by controlling dendritic protrusion dynamics.

Alexithymia may explain the relationship between autistic traits and eating disorder psychopathology

BACKGROUND

Autistic people are disproportionately vulnerable to anorexia nervosa and other eating disorders (ED), and within the general population, autistic traits correlate with ED psychopathology. A putative mechanism which may underpin this heightened risk is alexithymia, a difficulty identifying and describing emotional states which is observed in both autism and ED. In two experiments with independent non-clinical samples, we explored whether alexithymia might mediate the heightened risk of eating psychopathology in individuals high in autistic traits.

METHODS

Our first experiment used the PROCESS macro for SPSS to examine relationships between alexithymia (measured by the Toronto Alexithymia Scale (TAS-20)), autistic traits (autism quotient (AQ)), and eating psychopathology (Eating Attitudes Test (EAT-26)) in 121 participants. Our second experiment (n = 300) replicated and furthered this analysis by examining moderating effects of sex and controlling for anxiety and depression as covariates. We also included an additional performance-based measure of alexithymia, the Levels of Emotional Awareness Scale (LEAS).

RESULTS

Study 1 suggested that TAS-20 scores mediated the relationship between heightened autistic traits and eating psychopathology. Replication and further scrutiny of this finding, in study 2, revealed that this mediation effect was partial and specific to the female participants in this sample. The mediation effect appeared to be carried by the difficulty identifying feelings subscale of the TAS-20, even when depression and anxiety were controlled for. LEAS scores, however, were not significantly related to autistic traits or eating psychopathology.

LIMITATIONS

Cross-sectional data prevents any conclusions around the direction and causality of relationships between alexithymia, autistic traits, and eating psychopathology (alongside depression and anxiety), necessitating longitudinal research. Our non-clinical sample was predominantly Caucasian undergraduate students, so it remains to be seen if these results would extrapolate to clinical and/or autistic samples. Divergence between the TAS-20 and LEAS raises crucial questions regarding the construct validity of these measures.

CONCLUSIONS

Our findings with respect to autistic traits suggest that alexithymia could partially explain the prevalence of ED in autistic people and may as such be an important consideration in the pathogenesis and treatment of ED in autistic and non-autistic people alike. Further research with clinical samples is critical to explore these ideas. Differences between men and women, furthermore, emphasize the importance of looking for sex-specific as well as generic risk factors in autistic and non-autistic men and women.

Depression and Health Self-perception: Associations Within the Isolated Mennonite Population in South Brazil

The Mennonite population suffered several bottlenecks due to religious/political persecution, increasing the frequency of diseases with a strong genetic component. We evaluated health self-perception in 430 Mennonites from South Brazilian settlements (two rural, one urban), along with life habits, xenobiotic exposure, and chronic ilnesses, using a modified version of the 2013 Brazilian National Health Survey and eight psychometric tests (applied in 2016-2018). Mennonites from rural settlements considered their health worse (P < 0.0001). This was independently associated with any psychiatric disease (OR 3.10, P = 0.037), depression diagnosis (OR 2.39, P = 0.002), spinal pain (OR 1.76, P = 0.015), waist circumference (OR 1.02, P = 0.009) and geographic origin (OR 0.64, P = 0.003). In the multivariate analysis including the scales, independent association also occurred with higher anxiety (ASI-R: OR 6.48, P = 0.014) and depression scores (BDI: OR 6.72, P = 0.008). Thus, a worse health self-perception was unequivocally associated with diagnosed or present depression/anxiety, independent of other contributors, suggesting a strong link between both.

Targeting TDP-43 proteinopathy with drugs and drug-like small molecules

Following the discovery of the involvement of the ribonucleoprotein TDP-43 in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), a major research focus has been to develop treatments that can prevent or alleviate these disease conditions. One pharmacological approach has been to use TDP-43-based disease models to test small molecules and drugs already known to have some therapeutic effect in a variety of neurodegenerative conditions. In parallel, various disease models have been used to perform high-throughput screens of drugs and small compound libraries. The aim of this review will be to provide a general overview of the compounds that have been described to alter pathological characteristics of TDP-43. These include expression levels, cytoplasmic mis-localization, post-translational modifications, cleavage, stress granule recruitment and aggregation. In parallel, this review will also address the use of compounds that modify the autophagic/proteasome systems that are known to target TDP-43 misfolding and aggregation. LINKED ARTICLES: This article is part of a themed issue on Neurochemistry in Japan. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.6/issuetoc.

Absence of parvalbumin increases mitochondria volume and branching of dendrites in inhibitory Pvalb neurons in vivo: a point of convergence of autism spectrum disorder (ASD) risk gene phenotypes

Background

In fast firing, parvalbumin (PV)-expressing (Pvalb) interneurons, PV acts as an intracellular Ca²⁺ signal modulator with slow-onset kinetics. In Purkinje cells of PV^−/− mice, adaptive/homeostatic mechanisms lead to an increase in mitochondria, organelles equally capable of delayed Ca²⁺ sequestering/buffering. An inverse regulation of PV and mitochondria likewise operates in cell model systems in vitro including myotubes, epithelial cells, and oligodendrocyte-like cells overexpressing PV. Whether such opposite regulation pertains to all Pvalb neurons is currently unknown. In oligodendrocyte-like cells, PV additionally decreases growth and branching of processes in a cell-autonomous manner.

Methods

The in vivo effects of absence of PV were investigated in inhibitory Pvalb neurons expressing EGFP, present in the somatosensory and medial prefrontal cortex, striatum, thalamic reticular nucleus, hippocampal regions DG, CA3, and CA1 and cerebellum of mice either wild-type or knockout (PV^−/−) for the Pvalb gene. Changes in Pvalb neuron morphology and PV concentrations were determined using immunofluorescence, followed by 3D-reconstruction and quantitative image analyses.

Results

PV deficiency led to an increase in mitochondria volume and density in the soma; the magnitude of the effect was positively correlated with the estimated PV concentrations in the various Pvalb neuron subpopulations in wild-type neurons. The increase in dendrite length and branching, as well as thickness of proximal dendrites of selected PV^−/− Pvalb neurons is likely the result of the observed increased density and length of mitochondria in these PV^−/− Pvalb neuron dendrites. The increased branching and soma size directly linked to the absence of PV is assumed to contribute to the increased volume of the neocortex present in juvenile PV^−/− mice. The extended dendritic branching is in line with the hypothesis of local hyperconnectivity in autism spectrum disorder (ASD) and ASD mouse models including PV^−/− mice, which display all ASD core symptoms and several comorbidities including cortical macrocephaly at juvenile age.

Conclusion

PV is involved in most proposed mechanisms implicated in ASD etiology: alterations in Ca²⁺ signaling affecting E/I balance, changes in mitochondria structure/function, and increased dendritic length and branching, possibly resulting in local hyperconnectivity, all in a likely cell autonomous way.

The Key Role of Purine Metabolism in the Folate-Dependent Phenotype of Autism Spectrum Disorders: An In Silico Analysis

Folate deficiency in the critical developmental period has been repeatedly associated with an increased risk of Autism spectrum disorders (ASD), but the key pathophysiological mechanism has not yet been identified. In this work, we focused on identifying genes whose defect has similar consequences to folate depletion in the metabolic network. Within the Flux Balance Analysis (FBA) framework, we developed a method of blocked metabolites that allowed us to define the metabolic consequences of various gene defects and folate depletion. We identified six genes (GART, PFAS, PPAT, PAICS, ATIC, and ADSL) whose blocking results in nearly the same effect in the metabolic network as folate depletion. All of these genes form the purine biosynthetic pathway. We found that, just like folate depletion, the blockade of any of the six genes mentioned above results in a blockage of purine metabolism. We hypothesize that this can lead to decreased adenosine triphosphate (ATP) and subsequently, an S-adenosyl methionine (SAM) pool in neurons in the case of rapid cell division. Based on our results, we consider the methylation defect to be a potential cause of ASD, due to the depletion of purine, and consequently S-adenosyl methionine (SAM), biosynthesis.

One Single Nucleotide Polymorphism of the TRPM2 Channel Gene Identified as a Risk Factor in Bipolar Disorder Associates with Autism Spectrum Disorder in a Japanese Population

The transient receptor potential melastatin 2 (TRPM2) is a non-specific cation channel, resulting in Ca²⁺ influx at warm temperatures from 34 °C to 47 °C, thus including the body temperature range in mammals. TRPM2 channels are activated by β-NAD⁺, ADP-ribose (ADPR), cyclic ADPR, and 2′-deoxyadenosine 5′-diphosphoribose. It has been shown that TRPM2 cation channels and CD38, a type II or type III transmembrane protein with ADP-ribosyl cyclase activity, simultaneously play a role in heat-sensitive and NAD⁺ metabolite-dependent intracellular free Ca²⁺ concentration increases in hypothalamic oxytocinergic neurons. Subsequently, oxytocin (OT) is released to the brain. Impairment of OT release may induce social amnesia, one of the core symptoms of autism spectrum disorder (ASD). The risk of single nucleotide polymorphisms (SNPs) and variants of TRPM2 have been reported in bipolar disorder, but not in ASD. Therefore, it is reasonable to examine whether SNPs or haplotypes in TRPM2 are associated with ASD. Here, we report a case-control study with 147 ASD patients and 150 unselected volunteers at Kanazawa University Hospital in Japan. The sequence-specific primer-polymerase chain reaction method together with fluorescence correlation spectroscopy was applied. Of 14 SNPs examined, one SNP (rs933151) displayed a significant p-value (OR = 0.1798, 95% CI = 0.039, 0.83; Fisher’s exact test; p = 0.0196). The present research data suggest that rs93315, identified as a risk factor for bipolar disorder, is a possible association factor for ASD.

The anti-parasitic agent suramin and several of its analogues are inhibitors of the DNA binding protein Mcm10

Minichromosome maintenance protein 10 (Mcm10) is essential for DNA unwinding by the replisome during S phase. It is emerging as a promising anti-cancer target as MCM10 expression correlates with tumour progression and poor clinical outcomes. Here we used a competition-based fluorescence polarization (FP) high-throughput screening (HTS) strategy to identify compounds that inhibit Mcm10 from binding to DNA. Of the five active compounds identified, only the anti-parasitic agent suramin exhibited a dose-dependent decrease in replication products in an in vitro replication assay. Structure–activity relationship evaluation identified several suramin analogues that inhibited ssDNA binding by the human Mcm10 internal domain and full-length Xenopus Mcm10, including analogues that are selective for Mcm10 over human RPA. Binding of suramin analogues to Mcm10 was confirmed by surface plasmon resonance (SPR). SPR and FP affinity determinations were highly correlated, with a similar rank between affinity and potency for killing colon cancer cells. Suramin analogue NF157 had the highest human Mcm10 binding affinity (FP K_i 170 nM, SPR K_D 460 nM) and cell activity (IC₅₀ 38 µM). Suramin and its analogues are the first identified inhibitors of Mcm10 and probably block DNA binding by mimicking the DNA sugar phosphate backbone due to their extended, polysulfated anionic structures.

Increased sub-clinical levels of autistic traits are associated with reduced multisensory integration of audiovisual speech

Recent studies suggest that sub-clinical levels of autistic symptoms may be related to reduced processing of artificial audiovisual stimuli. It is unclear whether these findings extent to more natural stimuli such as audiovisual speech. The current study examined the relationship between autistic traits measured by the Autism spectrum Quotient and audiovisual speech processing in a large non-clinical population using a battery of experimental tasks assessing audiovisual perceptual binding, visual enhancement of speech embedded in noise and audiovisual temporal processing. Several associations were found between autistic traits and audiovisual speech processing. Increased autistic-like imagination was related to reduced perceptual binding measured by the McGurk illusion. Increased overall autistic symptomatology was associated with reduced visual enhancement of speech intelligibility in noise. Participants reporting increased levels of rigid and restricted behaviour were more likely to bind audiovisual speech stimuli over longer temporal intervals, while an increased tendency to focus on local aspects of sensory inputs was related to a more narrow temporal binding window. These findings demonstrate that increased levels of autistic traits may be related to alterations in audiovisual speech processing, and are consistent with the notion of a spectrum of autistic traits that extends to the general population.

Emerging Roles of Complement Protein C1q in Neurodegeneration

The innate immune system is an ancient and primary component system that rapidly reacts to defend the body against external pathogens. C1 is the initial responder of classical pathway of the innate immune system. C1 is comprised of C1q, C1r, and C1s. Among them, C1q is known to interact with diverse ligands, which can perform various functions in physiological and pathophysiological conditions. Because C1q participates in the clearance of pathogens, its interaction with novel receptors is expected to facilitate apoptosis induction, which could prevent the onset or progression of neurodegenerative diseases and could delay the aging process. Because senescence-associated secreting phenotype determinants are generally inflammatory cytokines or immune factors to activate immune cells. In the central nervous system, C1q has diverse neuroprotective roles against pathogens and inflammation. Most of neurodegenerative diseases show region specific pathology feature in the brain. It has been suggested the evidences that the active site and amount of C1q may be disease specific. This review considers currently the emerging and under-recognized roles of C1q in neurodegeneration and highlights the need for further research to clarify these roles. Future studies on the roles of C1q in regulating disease progression should consider these aspects, including the age-dependent onset time of each neurodegenerative disease progression.