The Notch signaling pathway inhibitor Dapt alleviates autism-like behavior, autophagy and dendritic spine density abnormalities in a valproic acid-induced animal model of autism

Impairments of social interaction in a valproic acid model in mice

Background

A rodent autism spectrum disorder (ASD) model based on prenatal exposure to valproic acid (VPA) is widely recognized as a prominent model. Social behavior in rodent ASD models has primarily been evaluated through a three-chamber approach test. However, in this study, we focused on social attention in the VPA model of ASD.

Methods

In male C57BL/6 J mice, attentional behaviors toward conspecifics were examined through reaching tasks around 9-11 weeks of age. On embryonic day 12.5, pregnant mice underwent a subcutaneous injection of 600 mg/kg VPA sodium salt dissolved in 0.9% saline solution (VPA group) or saline solution alone (Sal group) into their neck fat. Thirty-six mice-nine each in the VPA and saline groups, and 18 partners-underwent training in reaching behavior. Subsequently, we examined whether the VPA or Sal group demonstrated focused attention toward their partners during reaching tasks. A two-way analysis of variance (ANOVA) (condition [VPA/Sal] × situation [face-to-face (attention)/not paying attention (not attention)]) was conducted on the average success rate of the situation. Additionally, we measured the duration of sniffing behavior between pairs of mice in an open field twice in total at 4 and 8 weeks of age before reaching task. The pairs were constructed by pairing a VPA or Sal group mouse with its partner, with the objective of facilitating initial encounters between the mice. A one-way ANOVA was conducted on the average duration of sniffing behavior data from 4 weeks and a second one-way ANOVA on data from 8 weeks.

Results

The analysis revealed a significant interaction between condition and situation in the reaching task [F (1, 28) = 6.75, p = 0.015, ηp 2 = 0.19]. The simple main effect test exhibited that the "not paying attention" rate was significantly higher than that of the "face-to-face" in the VPA group (p < 0.01). The results revealed a not significant difference in the average duration of sniffing behavior at 4 weeks [F (3, 32) = 2.71, p = 0.06, n.s., ηp 2 = 0.20], but significant difference at 8 weeks [F (3, 32) = 4.12, p < 0.05, ηp 2 = 0.28]. Multiple comparisons using the Bonferroni method revealed significant differences in the sniffing duration at 8 weeks between from the partner toward the VPA mouse and from the partner toward the Sal mouse (p < 0.05).

Conclusion

The VPA rodent model of ASD exhibited differences in social attention compared to the saline group. By focusing on social attention and exploring various ASD models, insights can be gained from the neural mechanisms underlying gaze abnormalities during social interaction in individuals with ASD.

Aflatoxin B1 exposure deteriorates immune abnormalities in a BTBR T+ Itpr3tf/J mouse model of autism by increasing inflammatory mediators' production in CD19-expressing cells

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by deficiencies in communication, repetitive and stereotyped behavioral patterns, and difficulties in reciprocal social engagement. The presence of immunological dysfunction in ASD has been well established. Aflatoxin B1 (AFB1) is a prevalent mycotoxin found in food and feed, causing immune toxicity and hepatotoxicity. AFB1 is significantly elevated in several regions around the globe. Existing research indicates that prolonged exposure to AFB1 results in neurological problems. The BTBR T+ Itpr3tf/J (BTBR) mice, which were used as an autism model, exhibit the primary behavioral traits that define ASD, such as repeated, stereotyped behaviors and impaired social interactions. The main objective of this work was to assess the toxic impact of AFB1 in BTBR mice. This work aimed to examine the effects of AFB1 on the expression of Notch-1, IL-6, MCP-1, iNOS, GM-CSF, and NF-κB p65 by CD19+ B cells in the spleen of the BTBR using flow cytometry. We also verified the impact of AFB1 exposure on the mRNA expression levels of Notch-1, IL-6, MCP-1, iNOS, GM-CSF, and NF-κB p65 in the brain of BTBR mice using real-time PCR. The findings of our study showed that the mice treated with AFB1 in the BTBR group exhibited a substantial increase in the presence of CD19+Notch-1+, CD19+IL-6+, CD19+MCP-1+, CD19+iNOS+, CD19+GM-CSF+, and CD19+NF-κB p65+ compared to the mice in the BTBR group that were treated with saline. Our findings also confirmed that administering AFB1 to BTBR mice leads to elevated mRNA expression levels of Notch-1, IL-6, MCP-1, iNOS, GM-CSF, and NF-κB p65 in the brain, in comparison to BTBR mice treated with saline. The data highlight that exposure to AFB1 worsens immunological abnormalities by increasing the expression of inflammatory mediators in BTBR mice.

Long-Term Epigenetic Regulation of Foxo3 Expression in Neonatal Valproate-Exposed Rat Hippocampus with Sex-Related Differences

Perinatal exposure to valproic acid is commonly used for autism spectrum disorder (ASD) animal model development. The inhibition of histone deacetylases by VPA has been proposed to induce epigenetic changes during neurodevelopment, but the specific alterations in genetic expression underlying ASD-like behavioral changes remain unclear. We used qPCR-based gene expression and epigenetics tools and Western blotting in the hippocampi of neonatal valproic acid-exposed animals at 4 weeks of age and conducted the social interaction test to detect behavioral changes. Significant alterations in gene expression were observed in males, particularly concerning mRNA expression of Foxo3, which was significantly associated with behavioral changes. Moreover, notable differences were observed in H3K27ac chromatin immunoprecipitation, quantitative PCR (ChIP-qPCR), and methylation-sensitive restriction enzyme-based qPCR targeting the Foxo3 gene promoter region. These findings provide evidence that epigenetically regulated hippocampal Foxo3 expression may influence social interaction-related behavioral changes. Furthermore, identifying sex-specific gene expression and epigenetic changes in this model may elucidate the sex disparity observed in autism spectrum disorder prevalence.

The Notch1/Hes1 pathway regulates Neuregulin 1/ErbB4 and participates in microglial activation in rats with VPA-induced autism

The core clinical characteristics of autism, which is a neurodevelopmental disease, involve repetitive behavior and impaired social interactions. Studies have shown that the Notch and Neuregulin1 (NRG1) signaling pathways are abnormally activated in autism, but the mechanism by which these two signaling pathways interact to contribute to the progression of autism has not been determined. Our results suggest that the levels of Notch1, Hes1, NRG1, and phosphorylated ErbB4 in the cerebellum (CB), hippocampus (HC), and prefrontal cortex (PFC) were increased in rats with valproic acid (VPA)-induced autism compared to those in the Con group. However, 3, 5-difluorophenyl-L-alanyl-L-2-phenylglycine tert-butyl (DAPT), which is a Notch pathway inhibitor, ameliorated autism-like behavioral abnormalities and decreased the protein levels of NRG1 and phosphorylated ErbB4 in rats with VPA-induced autism; these results demonstrated that the Notch1/Hes1 pathway could participate in the pathogenesis of autism by regulating the NRG1/ErbB4 signaling pathway. Studies have shown that the Notch pathway regulates microglial differentiation and activation during the onset of neurological disorders and that microglia affect autism-like behavior via synaptic pruning. Therefore, we hypothesized that the Notch1/Hes1 pathway could regulate the NRG1/ErbB4 pathway and thus participate in the development of autism by regulating microglial functions. The present study showed that AG1478, which is an ErbB4 inhibitor, ameliorated the autism-like behaviors in a VPA-induced autism rat model, reduced abnormal microglial activation, and decreased NRG1 and Iba-1 colocalization; however, AG1478 did not alter Notch1/Hes1 activity. These results demonstrated that Notch1/Hes1 may participate in the microglial activation in autism by regulating NRG1/ErbB4, revealing a new mechanism underlying the pathogenesis of autism.

Identification and Analysis of ZIC-Related Genes in Cerebellum of Autism Spectrum Disorders

Objective

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder with significant genetic heterogeneity. The ZIC gene family can regulate neurodevelopment, especially in the cerebellum, and has been implicated in ASD-like behaviors in mice. We performed bioinformatic analysis to identify the ZIC gene family in the ASD cerebellum.

Methods

We explored the roles of ZIC family genes in ASD by investigating (i) the association of ZIC genes with ASD risk genes from the Simons Foundation Autism Research Initiative (SFARI) database and ZIC genes in the brain regions of the Human Protein Atlas (HPA) database; (ii) co-expressed gene networks of genes positively and negatively correlated with ZIC1, ZIC2, and ZIC3, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and receiver operating characteristic (ROC) curve analysis of genes in these networks; and (iii) the relationship between ZIC1, ZIC2, ZIC3, and their related genes with cerebellar immune cells and stromal cells in ASD patients.

Results

(i) ZIC1, ZIC2, and ZIC3 were associated with neurodevelopmental disorders and risk genes related to ASD in the human cerebellum and (ii) ZIC1, ZIC2, and ZIC3 were highly expressed in the cerebellum, which may play a pathogenic role by affecting neuronal development and the cerebellar internal environment in patients with ASD, including immune cells, astrocytes, and endothelial cells. (iii) OLFM3, SLC27A4, GRB2, TMED1, NR2F1, and STRBP are closely related to ZIC1, ZIC2, and ZIC3 in ASD cerebellum and have good diagnostic accuracy. (iv) ASD mice in the maternal immune activation model demonstrated that Zic3 and Nr2f1 levels were decreased in the immune-activated cerebellum.

Conclusion

Our study supports the role of ZIC1, ZIC2, and ZIC3 in ASD pathogenesis and provides potential targets for early and accurate prediction of ASD.

Cadmium exposure exacerbates immunological abnormalities in a BTBR T+ Itpr3tf/J autistic mouse model by upregulating inflammatory mediators in CD45R-expressing cells

Autism spectrum disorder (ASD) is a neurodevelopmental illness characterized by behavior, learning, communication, and social interaction abnormalities in various situations. Individuals with impairments usually exhibit restricted and repetitive actions. The actual cause of ASD is yet unknown. It is believed, however, that a mix of genetic and environmental factors may play a role in its development. Certain metals have been linked to the development of neurological diseases, and the prevalence of ASD has shown a positive association with industrialization. Cadmium chloride (Cd) is a neurotoxic chemical linked to cognitive impairment, tremors, and neurodegenerative diseases. The BTBR T+ Itpr3tf/J (BTBR) inbred mice are generally used as a model for ASD and display a range of autistic phenotypes. We looked at how Cd exposure affected the signaling of inflammatory mediators in CD45R-expressing cells in the BTBR mouse model of ASD. In this study, we looked at how Cd affected the expression of numerous markers in the spleen, including IFN-γ, IL-6, NF-κB p65, GM-CSF, iNOS, MCP-1, and Notch1. Furthermore, we investigated the effect of Cd exposure on the expression levels of numerous mRNA molecules in brain tissue, including IFN-γ, IL-6, NF-κB p65, GM-CSF, iNOS, MCP-1, and Notch1. The RT-PCR technique was used for this analysis. Cd exposure increased the number of CD45R+IFN-γ+, CD45R+IL-6+, CD45R+NF-κB p65+, CD45R+GM-CSF+, CD45R+GM-CSF+, CD45R+iNOS+, and CD45R+Notch1+ cells in the spleen of BTBR mice. Cd treatment also enhanced mRNA expression in brain tissue for IFN-γ, IL-6, NF-κB, GM-CSF, iNOS, MCP-1, and Notch1. In general, Cd increases the signaling of inflammatory mediators in BTBR mice. This study is the first to show that Cd exposure causes immune function dysregulation in the BTBR ASD mouse model. As a result, our study supports the role of Cd exposure in the development of ASD.

Three Decades of Valproate: A Current Model for Studying Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with increased prevalence and incidence in recent decades. Its etiology remains largely unclear, but it seems to involve a strong genetic component and environmental factors that, in turn, induce epigenetic changes during embryonic and postnatal brain development. In recent decades, clinical studies have shown that inutero exposure to valproic acid (VPA), a commonly prescribed antiepileptic drug, is an environmental factor associated with an increased risk of ASD. Subsequently, prenatal VPA exposure in rodents has been established as a reliable translational model to study the pathophysiology of ASD, which has helped demonstrate neurobiological changes in rodents, non-human primates, and brain organoids from human pluripotent stem cells. This evidence supports the notion that prenatal VPA exposure is a valid and current model to replicate an idiopathic ASD-like disorder in experimental animals. This review summarizes and describes the current features reported with this animal model of autism and the main neurobiological findings and correlates that help elucidate the pathophysiology of ASD. Finally, we discuss the general framework of the VPA model in comparison to other environmental and genetic ASD models.

STACCato: Supervised Tensor Analysis tool for studying Cell-cell Communication using scRNA-seq data across multiple samples and conditions

Research on cell-cell communication (CCC) is crucial for understanding biology and diseases. Many existing CCC inference tools neglect potential confounders, such as batch and demographic variables, when analyzing multi-sample, multi-condition scRNA-seq datasets. To address this significant gap, we introduce STACCato, a Supervised Tensor Analysis tool for studying Cell-cell Communication, that identifies CCC events and estimates the effects of biological conditions (e.g., disease status, tissue types) on such events, while adjusting for potential confounders. Application of STACCato to both simulated data and real scRNA-seq data of lupus and autism studies demonstrate that incorporating sample-level variables into CCC inference consistently provides more accurate estimations of disease effects and cell type activity patterns than existing methods that ignore sample-level variables. A computational tool implementing the STACCato framework is available on GitHub.

Azithromycin induces neurotoxicity in zebrafish by interfering with the VEGF/Notch signaling pathway

Azithromycin (AZM) is a widely used antibiotic in both human and veterinary medicine, and its use has significantly increased during the COVID-19 pandemic. However, potential adverse effects of AZM on aquatic organisms have not been well studied. In this study, we explored the neurotoxicity of AZM in zebrafish and delved into its underlying mechanisms. Our results showed that AZM exposure resulted in a spectrum of detrimental effects in zebrafish, encompassing abnormal behaviors, damaged neuronal development, aberrant lateral line nervous system development, vascular malformations and perturbed expression of genes related to neural development. Moreover, we observed a concentration-dependent exacerbation of these neurotoxic manifestations with increasing AZM concentrations. Notably, AZM induced excessive cell apoptosis and oxidative stress damage. In addition, alterations in the expression levels of the genes involved in the VEGF/Notch signaling pathway were evident in AZM-exposed zebrafish. Consequently, we hypothesize that AZM may induce neurotoxicity by influencing the VEGF/Notch signaling pathway. To validate this hypothesis, we introduced a VEGF signaling inhibitor, axitinib, and a Notch signaling agonist, valproic acid, alongside AZM exposure. Remarkably, the administration of these rescue compounds significantly mitigated the neurotoxic effects induced by AZM. This dual verification provides compelling evidence that AZM indeed induces neurotoxicity during the early developmental stages of zebrafish, primarily through its interference with the VEGF/Notch pathway. Innovatively, our study reveals the molecular mechanism of AZM-induced neurotoxicity from the perspective of the close connection between blood vessels and nervous system. These findings provide new insights into the potential mechanisms underlying the neurotoxic effect of antibiotics and highlight the need for further investigation into the ecotoxicological effects of antibiotics on aquatic organisms and the potential risks to human health.

Cancer drug repurposing in autism spectrum disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with uncertain origins. Understanding of the mechanisms underlying ASD remains limited, and treatments are lacking. Genetic diversity complicates drug development. Given the complexity and severity of ASD symptoms and the rising number of diagnoses, exploring novel therapeutic strategies is essential. Here, we focus on shared molecular pathways between ASD and cancer and highlight recent progress on the repurposing of cancer drugs for ASD treatment, such as mTOR inhibitors, histone deacetylase inhibitors, and anti-inflammatory agents. We discuss how to improve trial design considering drug dose and patient age. Lastly, the discussion explores the critical aspects of side effects, commercial factors, and the efficiency of drug-screening pipelines; all of which are essential considerations in the pursuit of repurposing cancer drugs for addressing core features of ASD.

Preclinical Evidence for the Role of the Yin/Yang Angiotensin System Components in Autism Spectrum Disorder: A Therapeutic Target of Astaxanthin

Autism spectrum disorder (ASD) prevalence is emerging with an unclear etiology, hindering effective therapeutic interventions. Recent studies suggest potential renin-angiotensin system (RAS) alterations in different neurological pathologies. However, its implications in ASD are unexplored. This research fulfills the critical gap by investigating dual arms of RAS and their interplay with Notch signaling in ASD, using a valproic acid (VPA) model and assessing astaxanthin's (AST) modulatory impacts. Experimentally, male pups from pregnant rats receiving either saline or VPA on gestation day 12.5 were divided into control and VPA groups, with subsequent AST treatment in a subset (postnatal days 34-58). Behavioral analyses, histopathological investigations, and electron microscopy provided insights into the neurobehavioral and structural changes induced by AST. Molecular investigations of male pups' cortices revealed that AST outweighs the protective RAS elements with the inhibition of the detrimental arm. This established the neuroprotective and anti-inflammatory axes of RAS (ACE2/Ang1-7/MasR) in the ASD context. The results showed that AST's normalization of RAS components and Notch signaling underscore a novel therapeutic avenue in ASD, impacting neuronal integrity and behavioral outcomes. These findings affirm the integral role of RAS in ASD and highlight AST's potential as a promising treatment intervention, inviting further neurological research implications.

The Notch1/Hes1 signaling pathway affects autophagy by adjusting DNA methyltransferases expression in a valproic acid-induced autism spectrum disorder model

As a pervasive neurodevelopmental disease, autism spectrum disorder (ASD) is caused by both hereditary and environmental elements. Research has demonstrated the functions of the Notch pathway and DNA methylation in the etiology of ASD. DNA methyltransferases DNMT3 and DNMT1 are responsible for methylation establishment and maintenance, respectively. In this study, we aimed to explore the association of DNA methyltransferases with the Notch pathway in ASD. Our results showed Notch1 and Hes1 were upregulated, while DNMT3A and DNMT3B were downregulated at the protein level in the prefrontal cortex (PFC), hippocampus (HC) and cerebellum (CB) of VPA-induced ASD rats compared with Control (Con) group. However, the protein levels of DNMT3A and DNMT3B were augmented after treatment with 3,5-difluorophenacetyl-L-alanyl-S-phenylglycine-2-butyl ester (DAPT), suggesting that abnormal Notch pathway activation may affect the expression of DNMT3A and DNMT3B. Besides, our previous findings revealed that the Notch pathway may participate in development of ASD by influencing autophagy. Therefore, we hypothesized the Notch pathway adjusts autophagy and contributes to ASD by affecting DNA methyltransferases. Our current results showed that after receiving the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine (5-Aza-2'dc), the VPA + DAPT+5-Aza-2'dc (V + D + Aza) group exhibited reduced social interaction ability and increased stereotyped behaviors, and decreased expression of DNMT3A, DNMT3B and autophagy-related proteins, but did not show changes in Notch1 and Hes1 protein levels. Our results indicated that the Notch1/Hes1 pathway may adjust DNMT3A and DNMT3B expression and subsequently affect autophagy in the occurrence of ASD, providing new insight into the pathogenesis of ASD.

N-acetylcysteine improves autism-like behavior by recovering autophagic deficiency and decreasing Notch-1/Hes-1 pathway activity

N-acetylcysteine (NAC) has been reported to improve social interaction behavior, irritability, self-injury, and anxiety-like behavior in autism. However, the molecular mechanism underlying the therapeutic roles of NAC in autism remains unknown. This study mainly aimed to investigate the therapeutic effect of NAC on valproic acid (VPA)-induced autism model and the underlying mechanisms. Our results showed that NAC ameliorated the deficits in sociability and the anxiety- and repetitive-like behaviors displayed by VPA-exposed rats. In addition, VPA exposure induced autophagic deficiency and enhanced Notch-1/Hes-1 pathway activity based on lowered Beclin-1 and LC3B levels, while increased expression of p62, Notch-1, and Hes-1 expression at the protein level. However, NAC recovered VPA-induced autophagic deficiency and reduced Notch-1/Hes-1 pathway activity in a VPA-exposed autism rat model and SH-SY5Y neural cells. The present results demonstrated that NAC improves autism-like behavioral abnormalities by inactivating Notch-1/Hes-1 signaling pathway and recovering autophagic deficiency. Taken together, this study helps to elucidate a novel molecular mechanism that underlies the therapeutic actions of NAC in autism and suggests its potential to ameliorate behavioral abnormalities in neurodevelopmental disorders.

The Notch pathway regulates autophagy after hypoxic-ischemic injury and affects synaptic plasticity

Following neonatal hypoxic-ischemia (HI) injury, it is crucial factor to reconstruct neural circuit and maintain neural network homeostasis for neurological recovery. A dynamic balance between the synthesis and degradation of synaptic protein is required for maintaining synaptic plasticity. Protein degradation is facilitated by autophagy. This study aimed to investigate the regulation of synaptic structural plasticity by the Notch pathway, by assessing changes in Notch pathway activation and their effects on synaptic proteins and autophagy after HI injury. The study involved 48 male newborn Yorkshire piglets, each weighing 1.0-1.5 kg and 3 days old. They were randomly assigned to two groups: the HI group and the Notch pathway inhibitor + HI group (n = 24 per group). Each group was further divided into six subgroups according to HI duration (n = 4 per group): a control subgroup, and 0-6, 6-12, 12-24, 24-48, and 48-72 h subgroups. The expression of Notch pathway-related proteins, including Notch1, Hes1, and Notch intracellular domains, increased following HI injury. The expression of autophagy proteins increased at 0-6 h and 6-12 h post-HI. The expression of synaptic proteins, such as postsynaptic density protein 95 (PSD95) and synaptophysin, increased 6-12 h and 12-24 h after HI, respectively. Notably, the increased expression of these proteins was reversed by a Notch pathway inhibitor. Transmission electron microscopy revealed the presence of autophagosome structures in synapses. These findings shed light on the underlying mechanisms of neurological recovery after HI injury and may provide insights into potential therapeutic targets for promoting neural circuit reconstruction and maintaining neural network homeostasis.

Maternal treatment with aripiprazole prevents the development of a valproic acid-induced autism-like phenotype in juvenile male mice

Autism spectrum disorder (ASD) describes a heterogeneous group of neurodevelopmental conditions characterized by deficits in social communication and repetitive behaviors. Aripiprazole (APZ) is an atypical antipsychotic that can safeguard mice against autism-like behavior induced by valproic acid (VPA). In the present study, we examined the effects of maternal treatment with APZ (10 mg/kg) in juvenile mice prenatally exposed to VPA on neurodevelopmental behaviors, social interactions, communication, and working memory, as well as synaptophysin (SYP), synaptosomal-associated protein, 25 kDa (SNAP-25) and microtubule-associated protein 2 (MAP-2) expression in the medial prefrontal cortex (mPFC) and cell viability in the hippocampus. In addition, to evaluate possible APZ interference with the anticonvulsant properties of VPA on pentylenetetrazole (PTZ)-induced seizures were evaluated. Maternal treatment with APZ significantly prevented body weight loss, self-righting, eye-opening, social interactions, social communication, and working memory deficits in mice prenatally exposed to VPA. Additionally, the decrease in the SYP, SNAP-25, and MAP-2 expressions in the mPFC and cell death in the hippocampus was prevented by APZ. Furthermore, APZ (10 mg/kg) did not interfere with the anticonvulsant effect of VPA (15 mg/kg) in animals with PTZ-induced seizures. These findings indicate that maternal treatment with APZ in pregnant mice exposed to VPA protects animals against the ASD-like behavioral phenotype, and this effect may be related, at least in part, to synaptic plasticity and neuronal protection in the PFC and hippocampus. APZ may serve as an effective pharmacological therapeutic target against autistic behaviors in the VPA animal model of ASD, which should be further investigated to verify its clinical relevance.

Prenatally VPA exposure is likely to cause autistic-like behavior in the rats offspring via TREM2 down-regulation to affect the microglial activation and synapse alterations

Microglial dysfunction has been reported in the valproic acid (VPA)-induced autism spectrum disorder (ASD) rat models. However, how does prenatal VPA exposure affect microglia remains to be elucidated. The triggering receptor expressed on myeloid cells 2 (TREM2) is revealed to be implicated in a range of microglia functions. However, reports on the association between TREM2 and VPA-induced ASD rat models are scarce. Our results showed that prenatal VPA exposure induced autistic-like behaviors, downregulated the levels of TREM2, up-regulated microglial activation, dysregulated microglial polarization, and altered synapse in offspring. TREM2 overexpression partly ameliorated microglia dysfunction and autistic-like behaviors in prenatal VPA-exposed rats. Our findings demonstrated that prenatally VPA exposure is likely to cause autistic-like behavior in the rat offspring via TREM2 down-regulation to affect the microglial activation, microglial polarization and synaptic pruning of microglia for the first time.

A potent and selective CXCR2 antagonist improves neuroimmune dysregulation through the inhibition of NF-κB and notch inflammatory signaling in the BTBR mouse model of autism

Autism comprises a broad range of neurodevelopmental disorders characterized by social communication deficits and repetitive and stereotyped behaviors. Chemokine receptor CXCR2 is expressed on neurons and is upregulated in neurological disorders. BTBR T+ Itpr3tf/J (BTBR) mice, a model for autism that shows the core features of ASD. Here, we studied the anti-inflammatory effect of a potent and selective CXCR2 antagonist SB332235 in the BTBR mice. The CXCR2 antagonist represents a promising therapeutic agent for several neuroinflammatory disorders. In this study, we investigated the effects of SB332235 administration on NF-κB-, Notch-1-, Notch-3-, GM-CSF-, MCP-1-, IL-6-, and IL-2- and TGF-β1-expressing CD40+ cells in BTBR and C57BL/6 (C57) mice in the spleen cells by flow cytometry. We further assessed the effect of SB332235 treatment on NF-κB, Notch-1, GM-CSF, MCP-1, IL-6, and IL-2 mRNA expression levels in the brain tissue by RT-PCR. We also explored the effect of SB332235 administration on NF-κB, GM-CSF, IL-6, and TGF-β1 protein expression levels in the brain tissue by western blotting. The SB332235-treated BTBR mice significantly decreases in CD40 + NF-κB+, CD40 + Notch-1+, CD40 + Notch-3+, CD40 + GM-CSF+, CD40 + MCP-1+, CD40 + IL-6+, and CD40 + IL-2+, and increases in CD40 + TGF-β1+ in the spleen cells. Our results further demonstrated that BTBR mice treated with SB332235 effectively decreased NF-κB, Notch-1, GM-CSF, MCP-1, IL-6, and IL-2, increasing TGF-β1 mRNA and protein expression levels in the brain tissue. In conclusion, these results indicate that SB332235 elicits an anti-inflammatory response by downregulating the inflammatory mediators and NF-κB/Notch inflammatory signaling in BTBR mice. This could represent a promising novel therapeutic target for autism treatment.

Roles of the Notch signaling pathway and microglia in autism

The Notch signaling pathway is mainly involved in the regulation of neural stem cell proliferation, survival and differentiation during the development of the central nervous system. As a neurodevelopmental disorder, autism is associated with an abnormal increase in the number of microglia in several brain regions. These findings suggest that the pathogenesis of autism may be related to the Notch signaling pathway and microglia. In this review, we discuss how Notch pathway activity leads to behavioral abnormalities such as learning and memory impairment by influencing neuronal biological activities. An increase in microglial protein synthesis and abnormal autophagy can affect synaptic development and lead to behavioral abnormalities, and all of these changes can lead to autism. Furthermore, the Notch signaling pathway regulates the activation and differentiation of microglia and promotes inflammatory responses, leading to the occurrence of autism. When excessive reactive oxygen species (ROS) secreted by microglia cannot be cleared by autophagy in a timely manner, Notch signaling pathway activity is affected, possibly further increasing susceptibility to autism. This review reveals the mechanism underlying the role of the Notch signaling pathway, microglia and their interaction in the pathogenesis of autism and provides a theoretical reference for targeted clinical therapies for autism.

De novo mutations within metabolism networks of amino acid/protein/energy in Chinese autistic children with intellectual disability

BACKGROUND

Autism spectrum disorder (ASD) is often accompanied by intellectual disability (ID). Despite extensive studies, however, the genetic basis for this comorbidity is still not clear. In this study, we tried to develop an analyzing pipeline for de novo mutations and possible pathways related to ID phenotype in ASD. Whole-exome sequencing (WES) was performed to screen de novo mutations and candidate genes in 79 ASD children together with their parents (trios). The de novo altering genes and relative pathways which were associated with ID phenotype were analyzed. The connection nodes (genes) of above pathways were selected, and the diagnostic value of these selected genes for ID phenotype in the study population was also evaluated.

RESULTS

We identified 89 de novo mutant genes, of which 34 genes were previously reported to be associated with ASD, including double hits in the EGF repeats of NOTCH1 gene (p.V999M and p.S1027L). Interestingly, of these 34 genes, 22 may directly affect intelligence quotient (IQ). Further analyses revealed that these IQ-related genes were enriched in protein synthesis, energy metabolism, and amino acid metabolism, and at least 9 genes (CACNA1A, ALG9, PALM2, MGAT4A, PCK2, PLEKHA1, PSME3, ADI1, and TLE3) were involved in all these three pathways. Seven patients who harbored these gene mutations showed a high prevalence of a low IQ score (< 70), a non-verbal language, and an early diagnostic age (< 4 years). Furthermore, our panel of these 9 genes reached a 10.2% diagnostic rate (5/49) in early diagnostic patients with a low IQ score and also reached a 10% diagnostic yield in those with both a low IQ score and non-verbal language (4/40).

CONCLUSION

We found some new genetic disposition for ASD accompanied with intellectual disability in this study. Our results may be helpful for etiologic research and early diagnoses of intellectual disability in ASD. Larger population studies and further mechanism studies are warranted.

Potential role of TGFΒ and autophagy in early crebellum development

During development, the interconnected generation of various neural cell types within the cerebellar primordium is essential. Over embryonic (E) days E9-E13, Purkinje cells (PCs), and cerebellar nuclei (CN) neurons are among the created primordial neurons. The molecular and cellular mechanisms fundamental for the early cerebellar neurogenesis, migration/differentiation, and connectivity are not clear yet. Autophagy has a vital role in controlling cellular phenotypes, such as epithelial-to-mesenchymal transition (EMT) and endothelial to mesenchymal transition (EndMT). Transforming growth factor-beta 1 (TGF-β1) is the main player in pre-and postnatal development and controlling cellular morphological type via various mechanisms, such as autophagy. Thus, we hypothesized that TGF-β1 may regulate early cerebellar development by modifying the levels of cell adhesion molecules (CAMs) and consequently autophagy pathway in the mouse cerebellar primordium. We demonstrated the stimulation of the canonical TGF-β1 signaling pathway at the point that concurs with the generation of the nuclear transitory zone and PC plate in mice. Furthermore, our data show that the stimulated TGF-β1 signaling pathway progressively and chronologically could upregulate the expression of β-catenin (CTNNB1) and N-cadherin (CDH2) with the most expression at E11 and E12, leading to upregulation of chromodomain helicase DNA binding protein 8 (CDH8) and neural cell adhesion molecule 1 (NCAM1) expression, at E12 and E13. Finally, we demonstrated that the stimulated TGF-β signaling pathway may impede the autophagic flux at E11/E12. Nevertheless, basal autophagy flux happens at earlier developmental phases from E9-E10. Our study determined potential role of the TGF-β signaling and its regulatory impacts on autophagic flux during cerebellar development and cadherin expression, which can facilitate the proliferation, migration/differentiation, and placement of PCs and the CN neurons in their designated areas.

Prefrontal Circuits guiding Social Preference: Implications in Autism Spectrum Disorder

Although Autism Spectrum Disorder (ASD) is increasing in diagnostic prevalence, treatment options are inadequate largely due to limited understanding of ASD's underlying neural mechanisms. Contributing to difficulties in treatment development is the vast heterogeneity of ASD, from physiological causes to clinical presentations. Recent studies suggest that distinct genetic and neurological alterations may converge onto similar underlying neural circuits. Therefore, an improved understanding of neural circuit-level dysfunction in ASD may be a more productive path to developing broader treatments that are effective across a greater spectrum of ASD. Given the social preference behavioral deficits commonly seen in ASD, dysfunction in circuits mediating social preference may contribute to the atypical development of social cognition. We discuss some of the animal models used to study ASD and examine the function and effects of dysregulation of the social preference circuits, notably the medial prefrontal cortex-amygdala and the medial prefrontal cortex-nucleus accumbens circuits, in these animal models. Using the common circuits underlying similar behavioral disruptions of social preference behaviors as an example, we highlight the importance of identifying disruption in convergent circuits to improve the translational success of animal model research for ASD treatment development.

mTOR-Dependent Spine Dynamics in Autism

Autism Spectrum Conditions (ASC) are a group of neurodevelopmental disorders characterized by deficits in social communication and interaction as well as repetitive behaviors and restricted range of interests. ASC are complex genetic disorders with moderate to high heritability, and associated with atypical patterns of neural connectivity. Many of the genes implicated in ASC are involved in dendritic spine pruning and spine development, both of which can be mediated by the mammalian target of rapamycin (mTOR) signaling pathway. Consistent with this idea, human postmortem studies have shown increased spine density in ASC compared to controls suggesting that the balance between autophagy and spinogenesis is altered in ASC. However, murine models of ASC have shown inconsistent results for spine morphology, which may underlie functional connectivity. This review seeks to establish the relevance of changes in dendritic spines in ASC using data gathered from rodent models. Using a literature survey, we identify 20 genes that are linked to dendritic spine pruning or development in rodents that are also strongly implicated in ASC in humans. Furthermore, we show that all 20 genes are linked to the mTOR pathway and propose that the mTOR pathway regulating spine dynamics is a potential mechanism underlying the ASC signaling pathway in ASC. We show here that the direction of change in spine density was mostly correlated to the upstream positive or negative regulation of the mTOR pathway and most rodent models of mutant mTOR regulators show increases in immature spines, based on morphological analyses. We further explore the idea that these mutations in these genes result in aberrant social behavior in rodent models that is due to these altered spine dynamics. This review should therefore pave the way for further research on the specific genes outlined, their effect on spine morphology or density with an emphasis on understanding the functional role of these changes in ASC.

Influence of Prenatal Drug Exposure, Maternal Inflammation, and Parental Aging on the Development of Autism Spectrum Disorder

Autism spectrum disorder (ASD) affects reciprocal social interaction and produces abnormal repetitive, restrictive behaviors and interests. The diverse causes of ASD are divided into genetic alterations and environmental risks. The prevalence of ASD has been rising for several decades, which might be related to environmental risks as it is difficult to consider that the prevalence of genetic disorders related to ASD would increase suddenly. The latter includes (1) exposure to medications, such as valproic acid (VPA) and selective serotonin reuptake inhibitors (SSRIs) (2), maternal complications during pregnancy, including infection and hypertensive disorders of pregnancy, and (3) high parental age. Epidemiological studies have indicated a pathogenetic role of prenatal exposure to VPA and maternal inflammation in the development of ASD. VPA is considered to exert its deleterious effects on the fetal brain through several distinct mechanisms, such as alterations of γ-aminobutyric acid signaling, the inhibition of histone deacetylase, the disruption of folic acid metabolism, and the activation of mammalian target of rapamycin. Maternal inflammation that is caused by different stimuli converges on a higher load of proinflammatory cytokines in the fetal brain. Rodent models of maternal exposure to SSRIs generate ASD-like behavior in offspring, but clinical correlations with these preclinical findings are inconclusive. Hypertensive disorders of pregnancy and advanced parental age increase the risk of ASD in humans, but the mechanisms have been poorly investigated in animal models. Evidence of the mechanisms by which environmental factors are related to ASD is discussed, which may contribute to the development of preventive and therapeutic interventions for ASD.

Medial prefrontal cortex Notch1 signalling mediates methamphetamine-induced psychosis via Hes1-dependent suppression of GABAB1 receptor expression

Methamphetamine (METH), a widely abused stimulant drug, induces psychosis in approximately half of abusers; this effect is becoming a major concern for society. Although the Notch1 signalling pathway has been shown to play a part in the pathogenesis of some psychiatric disorders, its role in METH-induced psychosis (MIP) is still unknown. Here, the METH-induced locomotor sensitization model in rodents is considered to represent the underlying neurochemical changes driving psychoses. We found that the Notch1 signalling was downregulated in the medial prefrontal cortex (mPFC) in sensitized mice. Direct genetic and pharmacological manipulations of Notch1 signalling bidirectionally altered METH-induced locomotor sensitization and other MIP-related behaviours through governing neuronal activity in the mPFC. Moreover, Notch1 signalling negatively regulated GABA_B1 receptor expression in the mPFC of METH-sensitized mice through Hes1, a transcriptional repressor in Notch1 signalling. Further, we show that Hes1 can directly bind to the GABA_B1 receptor promoter. Notably, pharmacological regulation of the GABA_B receptor in the mPFC reversed the changes in METH-induced locomotor sensitization caused by the dysfunction of Notch1 signalling. Together, our findings uncover a previously unrecognised Notch1-Hes1-GABA_B1 receptor-dependent mechanism involved in regulating mPFC neuronal activity and behavioural phenotypes in MIP. Our work provides mechanistic insight into the aetiology and pathophysiology of MIP.

Danzhi Xiaoyao Powder Promotes Neuronal Regeneration by Downregulating Notch Signaling Pathway in the Treatment of Generalized Anxiety Disorder

Background: Generalized anxiety disorder (GAD) is one of the most common types of anxiety disorders with unclear pathogenesis. Our team's previous research found that extensive neuronal apoptosis and neuronal regeneration disorders occur in the hippocampus of GAD rats. Danzhi Xiaoyao (DZXYS) Powder can improve the anxiety behavior of rats, but its molecular mechanism is not well understood. Objective: This paper discusses whether the pathogenesis of GAD is related to the abnormal expression of Notch signal pathway, and whether the anti-anxiety effect of DZXYS promotes nerve regeneration in the hippocampus by regulating the Notch signaling pathway. Methods: The animal model of GAD was developed by the chronic restraint stress and uncertain empty bottle stimulation method. After the model was successfully established, the rats in the model preparation group were divided into the buspirone, DZXYS, DZXYS + DAPT, and model groups, and were administered the corresponding drug intervention. The changes in body weight and food intake of rats were continuously monitored throughout the process. The changes in anxiety behavior of rats were measured by open field experiment and elevated plus-maze test, and morphological changes and regeneration of neurons in the rat hippocampus were observed by HE staining and double immunofluorescence staining. Changes in the expression of key targets of the Notch signaling pathway in the hippocampus were monitored by real-time fluorescence quantitative PCR and western blotting. Results: In this study, we verified that the GAD model was stable and reliable, and found that the key targets of the Notch signaling pathway (Notch1, Hes1, Hes5, etc.) in the hippocampus of GAD rats were significantly upregulated, leading to the increased proliferation of neural stem cells in the hippocampus and increased differentiation into astrocytes, resulting in neuronal regeneration. DZXYS intervention in GAD rats can improve appetite, promote weight growth, and significantly reverse the anxiety behavior of GAD rats, which can inhibit the upregulation of key targets of the Notch signaling pathway, promote the differentiation of neural stem cells in the hippocampus into neurons, and inhibit their differentiation into astrocytes, thus alleviating anxiety behavior. Conclusion: The occurrence of GAD is closely related to the upregulation of the Notch signaling pathway, which hinders the regeneration of normal neurons in the hippocampus, while DZXYS can downregulate the Notch signaling pathway and promote neuronal regeneration in the hippocampus, thereby relieving anxiety behavior.

nr0b1 (DAX1) loss of function in zebrafish causes hypothalamic defects via abnormal progenitor proliferation and differentiation

The nuclear receptor DAX-1 (encoded by the NR0B1 gene) is presented in the hypothalamic tissues in humans and other vertebrates. Human patients with NR0B1 mutations often have hypothalamic-pituitary defects, but the involvement of NR0B1 in hypothalamic development and function is not well understood. Here, we report the disruption of the nr0b1 gene in zebrafish causes abnormal expression of gonadotropins, a reduction in fertilization rate, and an increase in post-fasting food intake, which is indicative of abnormal hypothalamic functions. We find that loss of nr0b1 increases the number of prodynorphin (pdyn)-expressing neurons but decreases the number of pro-opiomelanocortin (pomcb)-expressing neurons in the zebrafish hypothalamic arcuate region (ARC). Further examination reveals that the proliferation of progenitor cells is reduced in the hypothalamus of nr0b1 mutant embryos accompanying with the decreased expression of genes in the Notch signaling pathway. Additionally, the inhibition of Notch signaling in wild-type embryos increases the number of pdyn neurons, mimicking the nr0b1 mutant phenotype. In contrast, ectopic activation of Notch signaling in nr0b1 mutant embryos decreases the number of pdyn neurons. Taken together, our results suggest that nr0b1 regulates neural progenitor proliferation and maintenance to ensure normal hypothalamic neuron development.

Criss-crossing autism spectrum disorder and adult neurogenesis

Autism spectrum disorder (ASD) comprises a group of multifactorial neurodevelopmental disorders primarily characterized by deficits in social interaction and repetitive behavior. Although the onset is typically in early childhood, ASD poses a lifelong challenge for both patients and caretakers. Adult neurogenesis (AN) is the process by which new functional neurons are created from neural stem cells existing in the post-natal brain. The entire event is based on a sequence of cellular processes, such as proliferation, specification of cell fate, maturation, and ultimately, synaptic integration into the existing neural circuits. Hence, AN is implicated in structural and functional brain plasticity throughout life. Accumulating evidence shows that impaired AN may underlie some of the abnormal behavioral phenotypes seen in ASD. In this review, we approach the interconnections between the molecular pathways related to AN and ASD. We also discuss existing therapeutic approaches targeting such pathways both in preclinical and clinical studies. A deeper understanding of how ASD and AN reciprocally affect one another could reveal important converging pathways leading to the emergence of psychiatric disorders.

Mitochondrial dysfunction: A hidden trigger of autism?

Autism is a heterogeneous neurodevelopmental and neuropsychiatric disorder with no precise etiology. Deficits in cognitive functions uncover at early stages and are known to have an environmental and genetic basis. Since autism is multifaceted and also linked with other comorbidities associated with various organs, there is a possibility that there may be a fundamental cellular process responsible for this. These reasons place mitochondria at the point of interest as it is involved in multiple cellular processes predominantly involving metabolism. Mitochondria encoded genes were taken into consideration lately because it is inherited maternally, has its own genome and also functions the time of embryo development. Various researches have linked mitochondrial mishaps like oxidative stress, ROS production and mt-DNA copy number variations to autism. Despite dramatic advances in autism research worldwide, the studies focusing on mitochondrial dysfunction in autism is rather minimal, especially in India. India, owing to its rich diversity, may be able to contribute significantly to autism research. It is vital to urge more studies in this domain as it may help to completely understand the basics of the condition apart from a genetic standpoint. This review focuses on the worldwide and Indian scenario of autism research; mitochondrial abnormalities in autism and possible therapeutic approaches to combat it.

Altered expression of lncRNAs in autism spectrum disorder

Long non-coding RNAs (lncRNAs) have been recognized as an important epigenetic factor in the evolution of neuropsychiatric conditions. We have selected five lncRNAs (DISC2, PRKAR2A-AS1, LOC105375675, LRRC2-AS1, and LOC101928237) to measure their expression in blood samples of children with autism spectrum disorder (ASD) versus children with normal development. Expressions of DISC2, PRKAR2A-AS1 and LOC101928237 have been enhanced in ASD cases compared with healthy children (Posterior Beta = 2.508, P value<0.0001; Posterior Beta = 2.793, P value = 0.014 and Posterior Beta = 1.646, P value <0.0001, respectively). On the other hand, expression of LRRC2-AS1 has been lower in ASD patients compared with controls (Posterior Beta = -3.781, P value<0.0001). Remarkably, expression of DISC2 and PRKAR2A-AS1 have been lower in girls compared with boys (Posterior Beta = -0.982, P value<0.0001 and Posterior Beta = -0.135, P value<0.0001, respectively). In addition, expression of DISC2 has been lower in ASD cases aged more than 6 compared with those aged less than 6 years (Posterior Beta = -0.876, P value = 0.003). DISC2, LOC101928237, LRRC2-AS1, and PRKAR2A-AS1 had the area under curve (AUC) values of 0.76, 0.90, 0.92, and 0.79 in distinguishing between ASD and healthy children. Expression levels of none of DISC2, LOC101928237, LOC105375675, LRRC2-AS1, and PRKAR2A-AS1 were correlated with age of ASD cases or healthy controls. A significant correlation was detected between expressions of DISC2 and PRKAR2A-AS1. There were inverse correlations between the following pairs of lncRNAs: DISC2/LRRC2-AS1, DISC2/LOC101928237, LRRC2-AS1/PRKAR2A-AS1, LOC101928237/LRRC2-AS1, and LOC101928237 /LOC105375675. We conclude that DISC2, LOC101928237, LRRC2-AS1, and PRKAR2A-AS1 might be used as potential markers for this condition.

Inhibition of Notch1 signaling reduces hepatocyte injury in nonalcoholic fatty liver disease via autophagy

Nonalcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease worldwide and an urgent target for clinical intervention. Notch1 signaling pathway activity was found to be related to the severity of NAFLD, but the specific mechanism is not precise. Here, we investigated the potential mechanisms of Notch1 signaling in the development of NAFLD. Firstly, we found that Notch1 signaling is activated in free fatty acids-treated HepG2 cells accompanied by lipid accumulation, apoptosis, oxidative stress, and mitochondrial damage, which could be alleviated by Notch1 inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). In the meantime, we found that administration of DAPT activated the autophagy pathway in NAFLD. Furthermore, the use of autophagy inhibitor chloroquine reversed the DAPT-mediated protective effect in NAFLD. All our results uncover a vital role of Notch1 in hepatocyte injury and metabolism of NAFLD, giving rise to a new sight for NAFLD treatment by regulation of Notch signaling and autophagy pathway.

Maternal folic acid supplementation prevents autistic behaviors in a rat model induced by prenatal exposure to valproic acid

Maternal FA supplementation at 4 mg kg⁻¹ rescued the development delay, anxiety and core autism-like behaviors, and restored the abnormal synaptic spine morphology and synaptic protein expression in mPFC in the male offspring prenatally exposed to VPA.

Maternal Immune Activation Alters Fetal Brain Development and Enhances Proliferation of Neural Precursor Cells in Rats

Maternal immune activation (MIA) caused by exposure to pathogens or inflammation during critical periods of neurodevelopment is a major risk factor for behavioral deficits and psychiatric illness in offspring. A spectrum of behavioral abnormalities can be recapitulated in rodents by inducing MIA using the viral mimetic, PolyI:C. Many studies have focused on long-term changes in brain structure and behavioral outcomes in offspring following maternal PolyI:C exposure, but acute changes in prenatal development are not well-characterized. Using RNA-Sequencing, we profiled acute transcriptomic changes in rat conceptuses (decidua along with nascent embryo and placenta) after maternal PolyI:C exposure during early gestation, which enabled us to capture gene expression changes provoked by MIA inclusive to the embryonic milieu. We identified a robust increase in expression of genes related to antiviral inflammation following maternal PolyI:C exposure, and a corresponding decrease in transcripts associated with nervous system development. At mid-gestation, regions of the developing cortex were thicker in fetuses prenatally challenged with PolyI:C, with females displaying a thicker ventricular zone and males a thicker cortical mantle. Along these lines, neural precursor cells (NPCs) isolated from fetal brains prenatally challenged with PolyI:C exhibited a higher rate of self-renewal. Expression of Notch1 and the Notch ligand, delta-like ligand 1, which are both highly implicated in maintenance of NPCs and nervous system development, was increased following PolyI:C exposure. These results suggest that MIA elicits rapid gene expression changes within the conceptus, including repression of neurodevelopmental pathways, resulting in profound alterations in fetal brain development.

mTOR Suppresses Macroautophagy During Striatal Postnatal Development and Is Hyperactive in Mouse Models of Autism Spectrum Disorders

Macroautophagy (hereafter referred to as autophagy) plays a critical role in neuronal function related to development and degeneration. Here, we investigated whether autophagy is developmentally regulated in the striatum, a brain region implicated in neurodevelopmental disease. We demonstrate that autophagic flux is suppressed during striatal postnatal development, reaching adult levels around postnatal day 28 (P28). We also find that mTOR signaling, a key regulator of autophagy, increases during the same developmental period. We further show that mTOR signaling is responsible for suppressing autophagy, via regulation of Beclin-1 and VPS34 activity. Finally, we discover that autophagy is downregulated during late striatal postnatal development (P28) in mice with in utero exposure to valproic acid (VPA), an established mouse model of autism spectrum disorder (ASD). VPA-exposed mice also display deficits in striatal neurotransmission and social behavior. Correction of hyperactive mTOR signaling in VPA-exposed mice restores social behavior. These results demonstrate that neurons coopt metabolic signaling cascades to developmentally regulate autophagy and provide additional evidence that mTOR-dependent signaling pathways represent pathogenic signaling cascades in ASD mouse models that are active during specific postnatal windows.

mTOR Suppresses Macroautophagy During Striatal Postnatal Development and Is Hyperactive in Mouse Models of Autism Spectrum Disorders

Macroautophagy (hereafter referred to as autophagy) plays a critical role in neuronal function related to development and degeneration. Here, we investigated whether autophagy is developmentally regulated in the striatum, a brain region implicated in neurodevelopmental disease. We demonstrate that autophagic flux is suppressed during striatal postnatal development, reaching adult levels around postnatal day 28 (P28). We also find that mTOR signaling, a key regulator of autophagy, increases during the same developmental period. We further show that mTOR signaling is responsible for suppressing autophagy, via regulation of Beclin-1 and VPS34 activity. Finally, we discover that autophagy is downregulated during late striatal postnatal development (P28) in mice with in utero exposure to valproic acid (VPA), an established mouse model of autism spectrum disorder (ASD). VPA-exposed mice also display deficits in striatal neurotransmission and social behavior. Correction of hyperactive mTOR signaling in VPA-exposed mice restores social behavior. These results demonstrate that neurons coopt metabolic signaling cascades to developmentally regulate autophagy and provide additional evidence that mTOR-dependent signaling pathways represent pathogenic signaling cascades in ASD mouse models that are active during specific postnatal windows.

AMBRA1, Autophagy, and the Extreme Male Brain Theory of Autism

The extreme male brain theory of autism posits that its male bias is mediated by exaggeration of male-biased sex differences in the expression of autism-associated traits found in typical populations. The theory is supported by extensive phenotypic evidence, but no genes have yet been described with properties that fit its predictions. The autophagy-associated gene AMBRA1 represents one of the top genome-wide “hits” in recent GWAS studies of schizophrenia, shows sex-differential expression, and has been linked with autism risk and traits in humans and mice, especially or exclusively among females. We genotyped the AMBRA1 autism-risk SNP in a population of typical humans who were scored for the dimensional expression of autistic and schizotypal traits. Females, but not males, homozygous for the GG genotype showed a significant increase in score for the single trait, the Autism Quotient-Imagination subscale, that exhibits a strong, significant male bias in typical populations. As such, females with this genotype resembled males for this highly sexually dimorphic, autism-associated phenotype. These findings support the extreme male brain hypothesis and indicate that sex-specific genetic effects can mediate aspects of risk for autism.

Penehyclidine hydrochloride defends against LPS-induced ALI in rats by mitigating endoplasmic reticulum stress and promoting the Hes1/Notch1 pathway

Penehyclidine hydrochloride (PHC) is a novel anticholinergic drug applied broadly in surgeries as a preanesthetic medication. A substantial amount of research indicates that PHC has lung defensive properties. Considering that endoplasmic reticulum (ER) stress exerts a crucial function in cell apoptosis associated with the lipopolysaccharides (LPS)-induced acute lung injury (ALI) model, we aimed to determine whether regulation of ER stress in the LPS-induced ALI model was associated with the lung defensive role of PHC. Adult male SD rats were administered LPS (5 mg/kg, intratracheally) followed by PHC (1.0 mg/kg, intravenously) for 24 h. The NR8383 alveolar macrophages were randomly separated into Sham, LPS (100 ng/mL), and PHC (1, 2.5, or 5 μg/mL) + LPS groups. PHC (1, 2.5, or 5 μg/mL) + LPS groups were treated with PHC alone for 1 h after LPS exposure. Posttreatment with PHC relieved LPS-induced pulmonary impairment and blocked LPS-mediated lung apoptosis, indicated by the downregulation of the lung apoptotic indicators malondialdehyde and superoxide dismutase in serum at 24 h after LPS-induced ALI. PHC (1-5 μg/mL) did not influence the activity of cultivated NR8383 alveolar macrophages in vitro. However, postconditioning with PHC dosage-dependently reduced LPS-mediated cell apoptosis. Additionally, many studies have indicated that PHC administration inhibits ER stress and initiates hairy and enhancer of split 1 (Hes1)/(Notch1) signaling by decreasing phosphorylated α subunit of eukaryotic initiation factor 2α (p-eIF2α)/eukaryotic translation initiation factor 2α (eIF2α) and Phospho-protein kinase R-like ER kinase (p-PERK)/ protein kinase R-like ER kinase (PERK) proportions; inhibiting C/EBP-homologous protein (CHOP), activating transcription factor 4 (ATF4), caspase-3, and Bcl2-associated x (Bax) activity; and enhancing notch1 intracellular domain (NICD), Notch1, B-cell lymphoma-2 (Bcl-2), and Hes1 activity in vivo and in vitro. In addition, the defensive functions of PHC on LPS-activated NR8383 alveolar macrophages were abrogated through the Notch1 pathway antagonist [(3,5-difluorophenacetyl)-1-alanyl] -phenylglycine-butyl ester (DAPT). In conclusion, PHC alleviates LPS-induced ALI by ameliorating ER stress-mediated apoptosis and promoting Hes1/Notch1 signaling in vivo and in vitro.