ASD-like Behaviors Research Articles

RPS23RG1 inhibits SORT1-mediated lysosomal degradation of MDGA2 to protect against autism.

Rationale: Mutations in the synaptic protein MAM domain containing glycosylphosphatidylinositol anchor 2 (MDGA2) have been associated with autism spectrum disorder (ASD). Therefore, elucidating the regulatory mechanisms of MDGA2 can help develop effective treatments for ASD. Methods: Liquid chromatography-tandem mass spectrometry was carried out to identify proteins interacting with the extracellular domain of RPS23RG1 and with MDGA2, followed by co-immunoprecipitation assays to confirm protein-protein interactions. RPS23RG1 and SORT1 levels were downregulated by siRNAs to study their effects on MDGA2 degradation, with additional applications of immunoblotting and immunostaining assays. Lysosome isolation was performed to determine the lysosomal degradation of MDGA2 further. Rps23rg1 knockout mice and Mdga2 +/- mice were subjected to various behavioral tests to study their ASD-like phenotypes. AAVs expressing MDGA2 were delivered in Rps23rg1 knockout mice, and RPS23RG1-derived peptide was delivered in Mdga2 +/- mice to study their rescuing effects. Results: We found that both RPS23RG1 and SORT1 interacted with MDGA2. MDGA2 was primarily degraded through the SORT1-mediated lysosomal degradation pathway. RPS23RG1 competed with SORT1 for MDGA2 binding to inhibit MDGA2 degradation. Furthermore, we showed that Rps23rg1 knockout mice exhibited decreased MDGA2 levels and ASD-like behaviors, whereas restoration of MDGA2 levels attenuated social defects in Rps23rg1 KO mice. Moreover, we identified a crucial region of RPS23RG1 for MDGA2 interaction and found that a peptide derived from this region not only bound MDGA2 and promoted MDGA2 levels, but also rescued social defects in Mdga2 +/- mice. Conclusion: Our findings highlight a crucial role of RPS23RG1 in antagonizing SORT1-mediated lysosomal degradation of MDGA2 and suggest a potential for targeting the RPS23RG1-MDGA2 axis to treat ASD with MDGA2 deficiency.

Unraveling pathogenesis and potential biomarkers for autism spectrum disorder associated with HIF1A pathway based on machine learning and experiment validation.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a high social burden and limited treatments. Hypoxic condition of the brain is considered an important pathological mechanism of ASD. HIF1A is a key participant in brain hypoxia, but its contribution to the pathophysiological landscape of ASD remains unclear. ASD-related datasets were obtained from GEO database, and HIF1A-related genes from GeneCards. Co-expression module analysis identified module genes, which were intersected with HIF1A-related genes to identify common genes. Machine learning identified hub genes from intersection genes and PPI networks were constructed to explore relationships among hub and HIF1A. Single-cell RNA sequencing analyzed hub gene distribution across cell clusters. ASD mouse model was created by inducing maternal immune activation (MIA) with poly(I:C) injections, verified through behavioral tests. Validation of HIF1A pathway and hub genes was confirmed through Western Blot, qPCR, and immunofluorescence in ASD mice and microglia BV-2 cells. Using CEMiTool and GeneCards, 45 genes associated with ASD and HIF1A pathway were identified. Machine learning identified CDKN1A, ETS2, LYN, and SLC16A3 as potential ASD diagnostic markers. Single-cell sequencing pinpointed activated microglia as key immune cells. Behavioral tests showed MIA offspring mice exhibited typical ASD-like behaviors. Immunofluorescence confirmed the activation of microglia and HIF1A pathway in frontal cortex of ASD mice. Additionally, IL-6 contributed to ASD by activating JUN/HIF1A pathway, affecting CDKN1A, LYN, and SLC16A3 expression in microglia. HIF1A-related genes CDKN1A, ETS2, LYN, and SLC16A3 are strong diagnostic markers for ASD and the activation of IL-6/JUN/HIF1A pathway in microglia contributes to the pathogenesis of ASD.

Role of immature choroid plexus in the pathology of model mice and human iPSC-derived organoids with autism spectrum disorder.

During gestation, the choroid plexus (ChP) produces protein-rich cerebrospinal fluid and matures prior to brain development. It is assumed that ChP dysfunction has a profound effect on developmental neuropsychiatric disorders, such as autism spectrum disorder (ASD). However, the mechanisms linking immature ChP to the onset of ASD remain unclear. Here, we find that ChP-specific CAMDI-knockout mice develop an immature ChP alongside decreased multiciliogenesis and expression of differentiation marker genes following disruption of the cerebrospinal fluid barrier. These mice exhibit ASD-like behaviors, including anxiety and impaired socialization. Additionally, the administration of metformin, an FDA-approved drug, before the social critical period achieves ChP maturation and restores social behaviors. Furthermore, both the ASD model mice and organoids derived from patients with ASD developed an immature ChP. These results propose the involvement of an immature ChP in the pathogenesis of ASD and suggest the targeting of functional maturation of the ChP as a therapeutic strategy for ASD.

Exploring the neurotoxic effects of microbial metabolites: A potential link between p-Cresol and autism spectrum disorders?

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a complex etiology, including genetic and environmental factors. A growing body of evidence (preclinical and clinical studies) implicates a potential role of gut microbiome dysregulation in ASD pathophysiology. This review focuses on the microbial metabolite p-Cresol, produced by certain gut bacteria such as Clostridium, and its potential role in ASD. The review summarizes studies investigating the gut microbiome composition in ASD patients, particularly the increased abundance of Clostridium species and associated gastrointestinal symptoms. The potential neurotoxic effects of p-Cresol are explored, including its influence on neurotransmitter metabolism (especially dopamine), neuroinflammation, and brain development. The mechanistic findings from the preclinical studies of p-Cresol's induction of ASD-like behaviors and its impact on the dopaminergic system are discussed. Literature studies indicated increased levels of p-Cresol in the urine of patients with ASD. This increasing evidence suggests that p-Cresol may serve as a crucial biomarker for understanding the relationship between gut microbiota and ASD, opening avenues for potential diagnostic and therapeutic interventions.

Autism Spectrum Disorder (ASD) or early electronic screen exposure – 67 month-old case study

Concerns about screen addiction have become increasingly prevalent, particularly with regard to its potential impact on children's development. This study examines the possible connection between Autism Spectrum Disorder (ASD) symptoms and early exposure to electronic screens. It focuses on a case involving a 67-month-old child who was heavily exposed to screens during the COVID-19 lockdown. The child spent an average of 5 hours per day in front of screens, which included television and mobile devices. Observations indicated delays in language development, poor social skills, and an anxious emotional state. The family initially associated these symptoms with ASD and sought professional consultation. However, it was observed that the child exhibited behaviors such as restlessness, avoidance of social interaction, and a preference for screen time over fulfilling basic needs, such as eating. These behaviors were particularly evident when the child was not engaged with digital devices, manifesting in sadness, frustration, and anger. The case highlights how early and excessive screen exposure can lead to developmental and psychological challenges that mimic ASD-like behaviors. Excessive screen time in children has been associated with attention disorders, sleep disturbances, language delays, and emotional instability. In this case, the family did not impose restrictions on screen usage during the lockdown period, which contributed to the child’s increased demand for digital media. The therapeutic intervention focused on reducing screen time and encouraging non-digital activities, including outdoor play and social interactions with peers. As a result, improvements were noted in the child’s anxiety, social engagement, and language development. In conclusion, this case underscores the importance of distinguishing between ASD and the effects of excessive screen exposure, as the symptoms of both conditions can overlap. Reducing screen time and promoting parent-child interactions are essential in mitigating these developmental issues.

Dysregulation of the mTOR-FMRP pathway and synapticplasticity in an environmental model of ASD.

Autism Spectrum Disorder (ASD) is caused by genetic, epigenetic, and environmental factors. Mutations in the human FMR1 gene, encoding the Fragile X Messenger Ribonucleoprotein 1 (FMRP), cause the most common monogenic form of ASD, the Fragile X Syndrome (FXS). This study explored the interaction between the FMR1 gene and a viral-like infection as an environmental insult, focusing on the impact on core autistic-like behaviors and the mGluR1/5-mTOR pathway. Pregnant heterozygous Fmr1 mouse females were exposed to maternal immune activation (MIA), by injecting the immunostimulant Poly (I:C) at the embryonic stage 12.5, simulating viral infections. Subsequently, ASD-like behaviors were analyzed in the adult offspring, at 8-10 weeks of age. MIA exposure in wild-type mice led to ASD-like behaviors in the adult offspring. These effects were specifically confined tothe intrauterine infection, as immune activation at later stages, namely puberty (Pubertal Immune Activation, PIA) at post-natal day 35 or adulthood (Adult Immune Activation, AIA) at post-natal day 56, did not alter adult behavior. Importantly, combining the Fmr1 mutation with MIA exposure did not intensify core autistic-like behaviors, suggesting an occlusion effect. Mechanistically, MIA provided a strong activation of the mGluR1/5-mTOR pathway, leading to increased LTP and downregulation of FMRP specifically in the hippocampus. Finally, FMRP modulates mTOR activity via TSC2. These findings further strengthen the key role of the mGluR1/5-mTOR pathway in causing ASD-like core symptoms.

Dysregulation of neuropilin-2 expression in inhibitory neurons impairs hippocampal circuit development and enhances risk for autism-related behaviors and seizures.

Dysregulation of development, migration, and function of interneurons, collectively termed interneuronopathies, have been proposed as a shared mechanism for autism spectrum disorders (ASDs) and childhood epilepsy. Neuropilin-2 (Nrp2), a candidate ASD gene, is a critical regulator of interneuron migration from the median ganglionic eminence (MGE) to the pallium, including the hippocampus. While clinical studies have identified Nrp2 polymorphisms in patients with ASD, whether selective dysregulation of Nrp2-dependent interneuron migration contributes to pathogenesis of ASD and enhances the risk for seizures has not been evaluated. We tested the hypothesis that the lack of Nrp2 in MGE-derived interneuron precursors disrupts the excitation/inhibition balance in hippocampal circuits, thus predisposing the network to seizures and behavioral patterns associated with ASD. Embryonic deletion of Nrp2 during the developmental period for migration of MGE derived interneuron precursors (iCKO) significantly reduced parvalbumin, neuropeptide Y, and somatostatin positive neurons in the hippocampal CA1. Consequently, when compared to controls, the frequency of inhibitory synaptic currents in CA1 pyramidal cells was reduced while frequency of excitatory synaptic currents was increased in iCKO mice. Although passive and active membrane properties of CA1 pyramidal cells were unchanged, iCKO mice showed enhanced susceptibility to chemically evoked seizures. Moreover, iCKO mice exhibited selective behavioral deficits in both preference for social novelty and goal-directed learning, which are consistent with ASD-like phenotype. Together, our findings show that disruption of developmental Nrp2 regulation of interneuron circuit establishment, produces ASD-like behaviors and enhanced risk for epilepsy. These results support the developmental interneuronopathy hypothesis of ASD epilepsy comorbidity.

Augmentation of Endogenous 2-Arachidonoylglycerol Mitigates Autistic Behaviors of BTBR Mice.

The lipid-based endocannabinoid (eCB) system regulates a host of developmental, physiological, and pathological processes in the mammalian brain, and recent studies have suggested that dysfunction of eCB system may contribute to the neuropathology of autism spectrum disorder (ASD). However, specific contributions to ASD-related developmental, cognitive, and behavioral phenotypes remain largely unexplored. The current study was designed to investigate if enhancing eCB signaling by blocking 2-arachidonoylglycerol (2-AG) hydrolase can mitigate ASD-like behaviors in a mouse model, and if such effects are associated with suppression of inflammatory signaling, oxidative stress, or neuronal apoptosis. Intraperitoneal injection of the 2-AG hydrolase monoacylglycerol lipase (MAGL) JZL184 (4, 16, or 40mg/kg) elevated 2-AG and reversed eCB system metabolic enzymes and receptors expression deficits in BTBR T + ltpr3tf/J (BTBR) mouse model of ASD. Moreover, the hyperactivity, excessive stereotypy, impaired social behavior, and cognitive deficits characteristic of this animal model were significantly improved by JZL184. Concomitantly, JZL184 administration reversed the abnormal pro- and anti-inflammatory cytokine concentrations measured in the hippocampus of BTBR mice. In addition, JZL184 reversed the observed overexpression of pro-apoptotic Bax and underexpression of anti-apoptotic Bcl-2 in BTBR mice and enhanced neuronal numbers in hippocampal CA1 and CA3 regions. We also found that the behavioral test battery influenced eCB concentrations independently of JZL184 treatment. Collectively, these findings suggest that augmenting eCB signaling can mitigate ASD-related phenotypes by suppressing neuroinflammation and neuronal apoptosis.

Lipopolysaccharide induces neuroinflammation in a valproic acid male model of autism

BackgroundAutism spectrum disorders (ASD) are characterized by social skill deficits and behavior impairments. Exposure to valproic acid (VPA) has been linked to ASD in humans and ASD-like behaviors in rodents. Clinical evidence suggests that immunological damage can worsen ASD symptoms in humans. ObjectiveThis study aimed to investigate the potential of lipopolysaccharide (LPS) to induce neuroinflammation in a VPA-induced autism male model. Materialsand methods: Pregnant Sprague Dawley rats were injected with 500mg/kg of VPA on gestational day 12.5 to create an ASD rat model in their offspring. Male offspring from VPA-injected group received 10mg/kg of LPS on postnatal day 20. Immunohistochemistry, western blotting, and immunofluorescence were used to assess the expression of NF-κB signaling pathway-related proteins and microglia in the prefrontal cortex and hippocampus. Gene Ontology and pathway enrichment analyses were conducted to predict the function of key synaptic proteins, which were further validated through real-time polymerase chain reaction analysis. ResultsThe results showed that VPA exposure led to increased locomotor activity, social impairment, and repetitive behaviors in male rats. NF-κB signaling pathway-related proteins were upregulated, and microglial numbers were elevated in the VPA-induced group. Furthermore, synaptic dysfunction was observed in the brains of offspring exposed to VPA. Importantly, LPS administration exacerbated autism-related behaviors in VPA-exposed male rats by promoting NF-κB signaling pathway activation, increasing microglial numbers, and downregulating key synaptic proteins. ConclusionsThis study not only contributed to understanding the importance of the NF-κB signaling pathway, microglia, and synaptic proteins in the progression of ASD, but also identified that LPS induces neuroinflammation in a valproic acid-induced male model of autism.

The Deficiency of the ASD-Related Gene CHD8 Disrupts Behavioral Patterns and Inhibits Hippocampal Neurogenesis in Mice.

Chromodomain helicase DNA-binding 8 (CHD8) is a gene that poses a high risk for autism spectrum disorder (ASD) and neurological development delay. Nevertheless, the impact of CHD8 haploinsufficiency on both hippocampus neurogenesis and behavior remains uncertain. Here, we performed behavioral assessments on male and female CHD8 heterozygous mice. The study discovered that both male and female CHD8 heterozygous mice displayed an impairment in preference for social novelty. Concurrently, CHD8 heterozygous mice exhibited anxiety-like behavior. However, its cognitive capacity for learning and memory is within the expected range. Furthermore, we discovered a reduction in the number of both immature and mature new neurons in mice with CHD8 heterozygous, resulting in an impeded neurogenesis process in the hippocampus. Taken together, our findings indicate that CHD8 plays a crucial role in the regulation of hippocampal neurogenesis, and further suggest that ASD-like behaviors observed in CHD8 heterozygous mice may be associated with disruptions in hippocampal neurogenesis.

Investigating brain–gut microbiota dynamics and inflammatory processes in an autistic-like rat model using MRI biomarkers during childhood and adolescence

Autism spectrum disorder (ASD) is characterized by social interaction deficits and repetitive behaviors. Recent research has linked that gut dysbiosis may contribute to ASD-like behaviors. However, the exact developmental time point at which gut microbiota alterations affect brain function and behavior in patients with ASD remains unclear. We hypothesized that ASD-related brain microstructural changes and gut dysbiosis induce metabolic dysregulation and proinflammatory responses, which collectively contribute to the social behavioral deficits observed in early childhood. We used an autistic-like rat model that was generated via prenatal valproic acid exposure. We analyzed brain microstructural changes using diffusion tensor imaging (DTI) and examined microbiota, blood, and fecal samples for inflammation biomarkers. The ASD model rats exhibited significant brain microstructural changes in the anterior cingulate cortex, hippocampus, striatum, and thalamus; reduced microbiota diversity (Prevotellaceae and Peptostreptococcaceae); and altered metabolic signatures. The shift in microbiota diversity and density observed at postnatal day (PND) 35, which is a critical developmental period, underscored the importance of early ASD interventions. We identified a unique metabolic signature in the ASD model, with elevated formate and reduced acetate and butyrate levels, indicating a dysregulation in short-chain fatty acid (SCFA) metabolism. Furthermore, increased astrocytic and microglial activation and elevated proinflammatory cytokines—interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α)—were observed, indicating immune dysregulation. This study provided insights into the complex interplay between the brain and the gut, and indicated DTI metrics as potential imaging-based biomarkers in ASD, thus emphasizing the need for early childhood interventions.

Soluble form of Lingo2, an autism spectrum disorder-associated molecule, functions as an excitatory synapse organizer in neurons

Autism Spectrum Disorder (ASD) is a developmental disorder characterized by impaired social communication and repetitive behaviors. In recent years, a pharmacological mouse model of ASD involving maternal administration of valproic acid (VPA) has become widely used. Newborn pups in this model show an abnormal balance between excitatory and inhibitory (E/I) signaling in neurons and exhibit ASD-like behavior. However, the molecular basis of this model and its implications for the pathogenesis of ASD in humans remain unknown. Using quantitative secretome analysis, we found that the level of leucine-rich repeat and immunoglobulin domain-containing protein 2 (Lingo2) was upregulated in the conditioned medium of VPA model neurons. This upregulation was associated with excitatory synaptic organizer activity. The secreted form of the extracellular domain of Lingo2 (sLingo2) is produced by the transmembrane metalloprotease ADAM10 through proteolytic processing. sLingo2 was found to induce the formation of excitatory synapses in both mouse and human neurons, and treatment with sLingo2 resulted in an increased frequency of miniature excitatory postsynaptic currents in human neurons. These findings suggest that sLingo2 is an excitatory synapse organizer involved in ASD, and further understanding of the mechanisms by which sLingo2 induces excitatory synaptogenesis is expected to advance our understanding of the pathogenesis of ASD.

MARK2 variants cause autism spectrum disorder via the downregulation of WNT/β-catenin signaling pathway

Microtubule affinity-regulating kinase 2 (MARK2) contributes to establishing neuronal polarity and developing dendritic spines. Although large-scale sequencing studies have associated MARK2 variants with autism spectrum disorder (ASD), the clinical features and variant spectrum in affected individuals with MARK2 variants, early developmental phenotypes in mutant human neurons, and the pathogenic mechanism underlying effects on neuronal development have remained unclear. Here, we report 31 individuals with MARK2 variants and presenting with ASD, other neurodevelopmental disorders, and distinctive facial features. Loss-of-function (LoF) variants predominate (81%) in affected individuals, while computational analysis and invitro expression assay of missense variants supported the effect of MARK2 loss. Using proband-derived and CRISPR-engineered isogenic induced pluripotent stem cells (iPSCs), we show that MARK2 loss leads to early neuronal developmental and functional deficits, including anomalous polarity and dis-organization in neural rosettes, as well as imbalanced proliferation and differentiation in neural progenitor cells (NPCs). Mark2+/- mice showed abnormal cortical formation and partition and ASD-like behavior. Through the use of RNA sequencing (RNA-seq) and lithium treatment, we link MARK2 loss to downregulation of the WNT/β-catenin signaling pathway and identify lithium as a potential drug for treating MARK2-associated ASD.

Autism spectrum disorder-like behaviors induced by hyper-glutamatergic NMDA receptor signaling through hypo-serotonergic 5-HT1A receptor signaling in the prefrontal cortex in mice exposed to prenatal valproic acid.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by repetitive behaviors, social deficits, and cognitive impairments. Maternal use of valproic acid (VPA) during pregnancy is associated with an increased risk of ASD in offspring. The prevailing pathophysiological hypothesis for ASD involves excitation/inhibition (E/I) imbalances and serotonergic dysfunction. Here, we investigated the association between glutamatergic-serotonergic neuronal interactions and ASD-like behaviors in mice exposed to prenatal VPA. Prenatal VPA exposure induced excessive repetitive self-grooming behavior and impaired social behavior and object recognition memory in young adult period. Prenatal VPA mice showed hyper-glutamatergic function (increase in basal extracellular glutamate levels and CaMKII phosphorylation) and hypo-serotonergic function (decrease in 5-hydroxyindoleacetic acid and stimulation-induced serotonin [5-HT] release, but an increase in 5-HT transporter expression) in the prefrontal cortex. Treatment with a low-affinity NMDA receptor antagonist (memantine), a selective 5-HT reuptake inhibitor (fluoxetine), and a 5-HT1A receptor agonist (tandospirone) attenuated both the increase in CaMKII phosphorylation and ASD-like behavior of prenatal VPA mice. Opto-genetic activation of the serotonergic neuronal system attenuated impairments in social behavior and object recognition memory in prenatal VPA mice. WAY-100635-a 5-HT1A receptor antagonist-antagonized the effect of fluoxetine on impaired social behavior and object recognition memory. These results suggest that E/I imbalance and ASD-like behavior are associated with hypo-serotonergic receptor signaling through 5-HT1A receptors in prenatal VPA mice.

Chronic administration of low dose aspirin alleviates ASD-like behaviors and activates AMPK in valproic acid-exposed rats

BackgroundAutism Spectrum Disorder (ASD) is a neurodevelopmental disorder distinguished by deficits in social communication and the presence of restricted/repetitive behaviors. There has been a global increase in the prevalence of ASD, yet the underlying causes of ASD remain inadequately understood, and there is currently no pharmacological intervention for the core symptoms of ASD. However, recent studies have suggested that aspirin may have the potential for use in the treatment of ASD. MethodPregnant rats were administered either VPA or normal saline on gestational day 12.5. The male pups were administered a low dose of aspirin (1 mg/kg) or a vehicle control daily from postnatal day 23 to day 52. ASD-like behaviors were assessed by social interaction, spontaneous grooming test, open field test and light-dark transitions. The activity of AMP-activated protein kinase (AMPK) was quantified by measuring the level of p-AMPK using an immunoblotting assay. ResultsChronic administration of low dose aspirin resulted in significant improvements in social approach deficits, a reduction in repetitive grooming, and the alleviation of anxiety-like behavior in ASD rats. Furthermore, aspirin administration also led to the activation of AMPK in the hippocampus of rats exposed to VPA. ConclusionsThese results raise the question of the need for further investigation of agents with mechanisms related to aspirin in ASD.

Animal Models of Autistic-like Behavior in Rodents: A Scoping Review and Call for a Comprehensive Scoring System

Appropriate animal models of human diseases are a cornerstone in the advancement of science and medicine. To create animal models of neuropsychiatric and neurobehavioral diseases such as autism spectrum disorder (ASD) necessitates the development of sufficient neurobehavioral measuring tools to translate human behavior to expected measurable behavioral features in animals. If possible, the severity of the symptoms should also be assessed. Indeed, at least in rodents, adequate neurobehavioral and neurological tests have been developed. Since ASD is characterized by a number of specific behavioral trends with significant severity, animal models of autistic-like behavior have to demonstrate the specific characteristic features, namely impaired social interactions, communication deficits, and restricted, repetitive behavioral patterns, with association to several additional impairments such as somatosensory, motor, and memory impairments. Thus, an appropriate model must show behavioral impairment of a minimal number of neurobehavioral characteristics using an adequate number of behavioral tests. The proper animal models enable the study of ASD-like-behavior from the etiologic, pathogenetic, and therapeutic aspects. From the etiologic aspects, models have been developed by the use of immunogenic substances like polyinosinic-polycytidylic acid (PolyIC), lipopolysaccharide (LPS), and propionic acid, or other well-documented immunogens or pathogens, like Mycobacterium tuberculosis. Another approach is the use of chemicals like valproic acid, polychlorinated biphenyls (PCBs), organophosphate pesticides like chlorpyrifos (CPF), and others. These substances were administered either prenatally, generally after the period of major organogenesis, or, especially in rodents, during early postnatal life. In addition, using modern genetic manipulation methods, genetic models have been created of almost all human genetic diseases that are manifested by autistic-like behavior (i.e., fragile X, Rett syndrome, SHANK gene mutation, neuroligin genes, and others). Ideally, we should not only evaluate the different behavioral modes affected by the ASD-like behavior, but also assess the severity of the behavioral deviations by an appropriate scoring system, as applied to humans. We therefore propose a scoring system for improved assessment of ASD-like behavior in animal models.

Alleviation of Autophagic Deficits and Neuroinflammation by Histamine H3 Receptor Antagonist E159 Ameliorates Autism-Related Behaviors in BTBR Mice

Background/Objectives: Autism spectrum disorder (ASD) is a neurodevelopmental condition marked by social interaction difficulties, repetitive behaviors, and immune dysregulation with elevated pro-inflammatory markers. Autophagic deficiency also contributes to social behavior deficits in ASD. Histamine H3 receptor (H3R) antagonism is a potential treatment strategy for brain disorders with features overlapping ASD, such as schizophrenia and Alzheimer’s disease. Methods: This study investigated the effects of sub-chronic systemic treatment with the H3R antagonist E159 on social deficits, repetitive behaviors, neuroinflammation, and autophagic disruption in male BTBR mice. Results: E159 (2.5, 5, and 10 mg/kg, i.p.) improved stereotypic repetitive behavior by reducing self-grooming time and enhancing spontaneous alternation in addition to attenuating social deficits. It also decreased pro-inflammatory cytokines in the cerebellum and hippocampus of treated BTBR mice. In BTBR mice, reduced expression of autophagy-related proteins LC3A/B and Beclin 1 was observed, which was elevated following treatment with E159, attenuating the disruption in autophagy. The co-administration with the H3R agonist MHA (10 mg/kg, i.p.) reversed these effects, highlighting the role of histaminergic neurotransmission in observed behavioral improvements. Conclusions: These preliminary findings suggest the therapeutic potential of H3R antagonists in targeting neuroinflammation and autophagic disruption to improve ASD-like behaviors.

Alterations in microbiota-metabolism-circRNA crosstalk in autism spectrum disorder-like behaviours caused by maternal exposure to glyphosate-based herbicides in mice

Epidemiological evidence indicates exposure to glyphosate-based herbicides (GBHs) increases the risk for autism spectrum disorder (ASD). The gut microbiota has been found to influence ASD behaviours through the microbiota-gut-brain axis. However, the underlying links between early life GBH exposure and ASD-like phenotypes through the microbiota-gut-brain axis remain unclear. Therefore, we exposed mice to low-dose GBH (0.10, 0.25, 0.50, and 1.00 %) and determined the effects on ASD-like behaviours. Furthermore, three kinds of omics (gut microbiomics, metabolomics, and transcriptomics) were conducted to investigate the effects of GBH exposure on gut microbiota, gut metabolites, and circular RNAs (circRNAs) in the prefrontal cortex (PFC) using a cross-generational mouse model. Behavioural analyses suggested social impairment and repetitive/stereotypic behaviours in the GBH-exposed offspring. Furthermore, maternal exposure to glyphosate significantly altered the ASD-associated gut microbiota of offspring, and ASD-associated gut metabolites were identified. Specifically, we found that alterations in the gut microenvironment may contribute to changes in gut permeability and the blood-brain barrier, which are related to changes in the levels of circRNAs in the PFC. Our results suggest a potential effect of circRNAs through the disruption of the gut-brain interaction, which is an important factor in the pathogenesis of ASD in offspring induced by maternal exposure to GBH.

Dysregulation of Neuropilin-2 Expression in Inhibitory Neurons Impairs Hippocampal Circuit Development and Enhances Risk for Autism-Related Behaviors and Seizures.

Dysregulation of development, migration, and function of interneurons, collectively termed interneuronopathies, have been proposed as a shared mechanism for autism spectrum disorders (ASDs) and childhood epilepsy. Neuropilin-2 (Nrp2), a candidate ASD gene, is a critical regulator of interneuron migration from the median ganglionic eminence (MGE) to the pallium, including the hippocampus. While clinical studies have identified Nrp2 polymorphisms in patients with ASD, whether selective dysregulation of Nrp2-dependent interneuron migration contributes to pathogenesis of ASD and enhances the risk for seizures has not been evaluated. We tested the hypothesis that the lack of Nrp2 in MGE-derived interneuron precursors disrupts the excitation/inhibition balance in hippocampal circuits, thus predisposing the network to seizures and behavioral patterns associated with ASD. Embryonic deletion of Nrp2 during the developmental period for migration of MGE derived interneuron precursors (iCKO) significantly reduced parvalbumin, neuropeptide Y, and somatostatin positive neurons in the hippocampal CA1. Consequently, when compared to controls, the frequency of inhibitory synaptic currents in CA1 pyramidal cells was reduced while frequency of excitatory synaptic currents was increased in iCKO mice. Although passive and active membrane properties of CA1 pyramidal cells were unchanged, iCKO mice showed enhanced susceptibility to chemically evoked seizures. Moreover, iCKO mice exhibited selective behavioral deficits in both preference for social novelty and goal-directed learning, which are consistent with ASD-like phenotype. Together, our findings show that disruption of developmental Nrp2 regulation of interneuron circuit establishment, produces ASD-like behaviors and enhanced risk for epilepsy. These results support the developmental interneuronopathy hypothesis of ASD epilepsy comorbidity.

Early-Life Exposure to 4-Hydroxy-4'-Isopropoxydiphenylsulfone Induces Behavioral Deficits Associated with Autism Spectrum Disorders in Mice.

Exposure to bisphenol A (BPA) during gestation and lactation is considered to be a potential risk factor for autism spectrum disorder (ASD) in both humans and animals. As a novel alternative to BPA, 4-hydroxy-4'-isopropoxydiphenylsulfone (BPSIP) is frequently detected in breast milk and placental barrier systems, suggesting potential transmission from the mother to offspring and increased risk of exposure. Gestation and lactation are critical periods for central nervous system development, which are vulnerable to certain environmental pollutants. Herein, we investigated the behavioral impacts and neurobiological effects of early-life exposure to BPSIP (0.02, 0.1, and 0.5 mg/kg body weight/day) in mice offspring. Behavioral studies indicated that BPSIP exposure induced ASD-like behaviors, including elevated anxiety-related behavior and decreased spatial memory, in both male and female pups. A distinct pattern of reduced social novelty was observed only in female offspring, accompanied by significant alterations in antioxidant levels. Transcriptome analysis demonstrated that differentially expressed genes (DEGs) were mainly enriched in pathways related to behaviors and neurodevelopment, which were consistent with the observed phenotype. Besides, a decrease in the protein levels of complex IV (COX IV) across all tested populations suggests a profound impact on mitochondrial function, potentially leading to abnormal energy metabolism in individuals with autism. Additionally, changes in synaptic proteins, evidenced by alterations in synapsin 1 (SYN1) and postsynaptic density protein-95 (PSD95) levels in the cerebellum and hippocampus, support the notion of synaptic involvement. These findings suggest that BPSIP may induce sex-specific neurotoxic effects that involve oxidative stress, energy generation, and synaptic plasticity.