Abnormal neuronal morphology and altered synaptic proteins are restored by oxytocin in autism-related SHANK3 deficient model

Shank3 Deficiency Results in a Reduction in GABAergic Postsynaptic Puncta in the Olfactory Brain Areas

Dysfunctional sensory systems, including altered olfactory function, have recently been reported in patients with autism spectrum disorder (ASD). Disturbances in olfactory processing can potentially result from gamma-aminobutyric acid (GABA)ergic synaptic abnormalities. The specific molecular mechanism by which GABAergic transmission affects the olfactory system in ASD remains unclear. Therefore, the present study aimed to evaluate selected components of the GABAergic system in olfactory brain regions and primary olfactory neurons isolated from Shank3-deficient (-/-) mice, which are known for their autism-like behavioral phenotype. Shank3 deficiency led to a significant reduction in GEPHYRIN/GABAAR colocalization in the piriform cortex and in primary neurons isolated from the olfactory bulb, while no change of cell morphology was observed. Gene expression analysis revealed a significant reduction in the mRNA levels of GABA transporter 1 in the olfactory bulb and Collybistin in the frontal cortex of the Shank3-/- mice compared to WT mice. A similar trend of reduction was observed in the expression of Somatostatin in the frontal cortex of Shank3-/- mice. The analysis of the expression of other GABAergic neurotransmission markers did not yield statistically significant results. Overall, it appears that Shank3 deficiency leads to changes in GABAergic synapses in the brain regions that are important for olfactory information processing, which may represent basis for understanding functional impairments in autism.

Intranasal oxytocin in a genetic animal model of autism

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders mainly characterized by deficient sociability and repetitive behaviors. Effective treatment for the core symptoms of ASD is still lacking. Behavioral interventions show limited effectiveness, while pharmacotherapy focuses on the amelioration of secondary symptomatology. Oxytocin (OXT) is a neuropeptide known for its prosocial impact, making it a candidate drug for ASD treatment. Its alleviating effect has been and still is widely researched, but outcomes reported by clinical studies are ambiguous. We examined the effect of daily intranasal OXT (0.8 IU/kg) administration for 4 weeks on the ASD-like phenotype in Shank3-/- adult mice. Animals treated with OXT spent twice as much time interacting with the social partner as early as after 2 weeks of treatment. Furthermore, OXT-treated mice exhibited reduced explorative behavior by 50%, after 4 weeks of treatment, and a 30% reduction in repetitive behavior, 4 weeks after treatment termination. One-fold higher sociability and 30% reduced exploration due to OXT lasted up to 4 weeks following the treatment termination. However, social disinterest was elevated by roughly 10% as well, indicating a form of social ambivalence. Obtained results support the therapeutic potential of intranasally administered OXT in alleviating social shortfalls in a genetic model of ASD. Subsequent research is necessary to elucidate the benefits and risks of the long-term OXT administration, as well as its applicability in other ASD models and the potential treatment effect on social communication, which was not measured in the present study.

Effect of a New Substance with Pyridoindole Structure on Adult Neurogenesis, Shape of Neurons, and Behavioral Outcomes in a Chronic Mild Stress Model in Rats

Despite an accumulating number of studies, treatments for depression are currently insufficient. Therefore, the search for new substances with antidepressant potential is very important. In this study, we hypothesized that treatment with a newly synthesized pyridoindole derivative compound SMe1EC2M3 would result in protective and antidepressant-like effects on behavioral outcomes and reverse the impaired adult hippocampal neurogenesis caused by chronic mild stress (CMS). We found that chronic administration of 5 mg/kg and 25 mg/kg SMe1EC2M3 to adult Sprague Dawley rats ameliorated the consequences of CMS on immobility and swimming time in a forced swim test. A slight sedative effect of the highest dose of SMe1EC2M3 in the nonstress group was observed in the open field. SMe1EC2M3 in the highest dose ameliorated CMS-induced decreases in the sucrose preference test. Administration of SMe1EC2M3 significantly increased SOX2-positive cells in the hippocampal dentate gyrus (DG) in CMS compared to control animals. A significant reduction in glial fibrillary acid protein (GFAP)-positive cells in the DG of CMS compared to control animals was observed. Administration of both 5 and 25 mg/kg SMe1EC2M3 significantly increased signal of GFAP-positive cells in the DG of CMS animals. No such effects of SMe1EC2M3 were observed in the cornu ammonis hippocampal area. Additionally, we found that incubation of primary hippocampal neurons in the presence of 1.50 µM SMe1EC2M3 significantly stimulated the length of neurites. Overall, we found that the negative effects of CMS on depression-like behavior are partially reduced by the administration of SMe1EC2M3 and are associated with changes in hippocampal neurogenesis and neuronal differentiation. SMe1EC2M3 represents a potential drug candidate with positive neuroplastic effects and neurogenesis-associated effects in therapeutic approaches to depression.

Enhancing social behavior in an autism spectrum disorder mouse model: investigating the underlying mechanisms of Lactiplantibacillus plantarum intervention

Autism spectrum disorder (ASD) is a neurodevelopmental disorder affecting over 1% of the global population. Individuals with ASD often exhibit complex behavioral conditions, including significant social difficulties and repetitive behaviors. Moreover, ASD often co-occurs with several other conditions, including intellectual disabilities and anxiety disorders. The etiology of ASD remains largely unknown owing to its complex genetic variations and associated environmental risks. Ultimately, this poses a fundamental challenge for the development of effective ASD treatment strategies. Previously, we demonstrated that daily supplementation with the probiotic Lactiplantibacillus plantarum PS128 (PS128) alleviates ASD symptoms in children. However, the mechanism underlying this improvement in ASD-associated behaviors remains unclear. Here, we used a well-established ASD mouse model, induced by prenatal exposure to valproic acid (VPA), to study the physiological roles of PS128 in vivo. Overall, we showed that PS128 selectively ameliorates behavioral abnormalities in social and spatial memory in VPA-induced ASD mice. Morphological examination of dendritic architecture further revealed that PS128 facilitated the restoration of dendritic arborization and spine density in the hippocampus and prefrontal cortex of ASD mice. Notably, PS128 was crucial for restoring oxytocin levels in the paraventricular nucleus and oxytocin receptor signaling in the hippocampus. Moreover, PS128 alters the gut microbiota composition and increases the abundance of Bifidobacterium spp. and PS128-induced changes in Bifidobacterium abundance positively correlated with PS128-induced behavioral improvements. Together, our results show that PS128 treatment can effectively ameliorate ASD-associated behaviors and reinstate oxytocin levels in VPA-induced mice, thereby providing a promising strategy for the future development of ASD therapeutics.

Neonatal oxytocin treatment alters levels of precursor and mature BDNF forms and modifies the expression of neuronal markers in the male rat hippocampus

Neuropeptide oxytocin appears to be involved in the formation of hippocampal circuitry, underlying social memory and behaviour. Recent studies point to the role of oxytocin in regulating the levels of nerve growth factors that could influence neurogenesis and neuritogenesis during the early stages of brain development. Therefore, the aim of the present study was to evaluate the early developmental effect of oxytocin administration (P2 and P3 days, two doses, 5 μg/pup, s.c.) on the expression of 1) brain-derived neurotrophic factor (BDNF) isoforms and 2) GABAergic and glutamatergic markers in the male rat hippocampus. Furthermore, we evaluated the branching of dendrites of primary hippocampal GABAergic and glutamatergic neurons in response to incubation with oxytocin (1 μM). We found that after oxytocin administration, levels of proBDNF increased on P5 and mBDNF on P7 in the CA1 hippocampal region. We also observed a reduction in the expression of glutamatergic marker (VGluT2) on P7 compared to P5 in control and oxytocin treated rats. During the early developmental stages (P5, P7, P9) the expression of GABAergic markers (Gad65 and Gad67) decreased regardless of oxytocin treatment. Incubation in a presence of oxytocin reduced branching of glutamatergic hippocampal neurons and the opposite stimulatory effect of oxytocin was observed in GABAergic neurons. These findings suggest that oxytocin affects neurotrophin isoforms in the male rat hippocampus in the early stages of development, which could explain changes in glutamatergic neurons and their morphology.

Targeting Shank3 deficiency and paresthesia in autism spectrum disorder: A brief review

Autism spectrum disorder (ASD) includes a group of multifactorial neurodevelopmental disorders characterized by impaired social communication, social interaction, and repetitive behaviors. Several studies have shown an association between cases of ASD and mutations in the genes of SH3 and multiple ankyrin repeat domain protein 3 (SHANK3). These genes encode many cell adhesion molecules, scaffold proteins, and proteins involved in synaptic transcription, protein synthesis, and degradation. They have a profound impact on all aspects of synaptic transmission and plasticity, including synapse formation and degeneration, suggesting that the pathogenesis of ASD may be partially attributable to synaptic dysfunction. In this review, we summarize the mechanism of synapses related to Shank3 in ASD. We also discuss the molecular, cellular, and functional studies of experimental models of ASD and current autism treatment methods targeting related proteins.

Elevation of SHANK3 Levels by Antisense Oligonucleotides Directed Against the 3'-UTR of the Human SHANK3 mRNA

SHANK3 is a member of the SHANK family of scaffolding proteins that localize to the postsynaptic density of excitatory synapses. Mutations within the SHANK3 gene or SHANK3 haploinsufficiency is thought to be one of the major causes for Phelan-McDermid Syndrome (PMDS) that is characterized by a broad spectrum of autism-related behavioral alterations. Several approaches have already been proposed to elevate SHANK3 protein levels in PMDS patients like transcriptional activation or inhibition of SHANK3 degradation. We undertook a systematic screening approach and tested whether defined antisense oligonucleotides (ASOs) directed against the 3' untranslated region (3'-UTR) of the human SHANK3 mRNA are suitable to elevate SHANK3 protein levels. Using human induced pluripotent stem cells (hiPSCs) and hiPSCs-derived motoneurons from controls and PMDS patients we eventually identified two 18 nucleotide ASOs (ASO 4-5.2-4 and 4-5.2-6) that were able to increase SHANK3 protein levels in vitro by about 1.3- to 1.6-fold. These findings were confirmed by co-transfection of the identified ASOs with a GFP-SHANK3-3'-UTR construct in HEK293T cells using GFP protein expression as read-out. Based on these results we propose a novel approach to elevate SHANK3 protein concentrations by 3'-UTR specific ASOs. Further research is needed to test the suitability of SHANK3-specific ASOs as pharmacological compounds also in vivo.

Oxytocin action on components of endoplasmic reticulum in hippocampal neuronal cells

Despite the known importance of the endoplasmic reticulum (ER) in protein synthesis and vesicular transport, it is not clear whether neuropeptide and neuromodulator oxytocin can directly affect components of the ER in neuronal cells. Therefore, in the present study, we hypothesize that incubation of hippocampal neuronal cells in a presence of oxytocin 1) plays a role in the regulation of the expression of selected ER chaperone components and molecules involved in unfolded protein response pathway 2) affects distribution of the intracellular fluorescence signal highly selective for the ER. We found that oxytocin (1 μM) after 60 min significantly decreased the gene expression of oxidoreductase Ero1β, chaperone glucose-regulated proteins (Grp) 78 and Grp94. A significant decrease in GRP78 protein levels in response to oxytocin treatment occurred after 30, 60 and 120 min. We also observed a time-dependent increase in calreticulin protein levels with a statistically significant increase observed after 360 min. We found that the dynamics of the ER network changes significantly within 2 h of incubation under the influence of oxytocin. In conclusion we have shown that ER chaperones, oxidoreductases and trafficking molecules in neuronal cells are changing in response to oxytocin treatment in a short-term scenario potentially relevant for growth of dendrites and axons.

Involvement of oxytocin receptor deficiency in psychiatric disorders and behavioral abnormalities

Oxytocin and its target receptor (oxytocin receptor, OXTR) exert important roles in the regulation of complex social behaviors and cognition. The oxytocin/OXTR system in the brain could activate and transduce several intracellular signaling pathways to affect neuronal functions or responses and then mediate physiological activities. The persistence and outcome of the oxytocin activity in the brain are closely linked to the regulation, state, and expression of OXTR. Increasing evidence has shown that genetic variations, epigenetic modification states, and the expression of OXTR have been implicated in psychiatric disorders characterized by social deficits, especially in autism. Among these variations and modifications, OXTR gene methylation and polymorphism have been found in many patients with psychiatric disorders and have been considered to be associated with those psychiatric disorders, behavioral abnormalities, and individual differences in response to social stimuli or others. Given the significance of these new findings, in this review, we focus on the progress of OXTR's functions, intrinsic mechanisms, and its correlations with psychiatric disorders or deficits in behaviors. We hope that this review can provide a deep insight into the study of OXTR-involved psychiatric disorders.

The Effect of Limosilactobacillus reuteri on Social Behavior Is Independent of the Adaptive Immune System

Gut microbes can modulate almost all aspects of host physiology throughout life. As a result, specific microbial interventions are attracting considerable attention as potential therapeutic strategies for treating a variety of conditions. Nonetheless, little is known about the mechanisms through which many of these microbes work. Recently, we and others have found that the commensal bacterium Limosilactobacillus reuteri (formerly Lactobacillus reuteri) reverses social deficits in several mouse models (genetic, environmental, and idiopathic) for neurodevelopmental disorders in a vagus nerve-, oxytocin-, and biopterin-dependent manner. Given that gut microbes can signal to the brain through the immune system and L. reuteri promotes wound healing via the adaptive immune response, we sought to determine whether the prosocial effect mediated by L. reuteri also depends on adaptive immunity. Here, we found that the effects of L. reuteri on social behavior and related changes in synaptic function are independent of the mature adaptive immune system. Interestingly, these findings indicate that the same microbe (L. reuteri) can affect different host phenotypes through distinct mechanisms. IMPORTANCE Because preclinical animal studies support the idea that gut microbes could represent novel therapeutics for brain disorders, it is essential to fully understand the mechanisms by which gut microbes affect their host's physiology. Previously, we discovered that treatment with Limosilactobacillus reuteri selectively improves social behavior in different mouse models for autism spectrum disorder through the vagus nerve, oxytocin reward signaling in the brain, and biopterin metabolites (BH4) in the gut. However, given that (i) the immune system remains a key pathway for host-microbe interactions and that (ii) L. reuteri has been shown to facilitate wound healing through the adaptive immune system, we examined here whether the prosocial effects of L. reuteri require immune signaling. Unexpectedly, we found that the mature adaptive immune system (i.e., conventional B and T cells) is not required for L. reuteri to reverse social deficits and related changes in synaptic function. Overall, these findings add new insight into the mechanism through which L. reuteri modulates brain function and behavior. More importantly, they highlight that a given bacterial species can modulate different phenotypes (e.g., wound healing versus social behavior) through separate mechanisms.

Oxytocin accelerates tight junction formation and impairs cellular migration in 3D spheroids: evidence from Gapmer-induced exon skipping

Oxytocin (OXT) is a neuropeptide that has been associated with neurological diseases like autism, a strong regulating activity on anxiety and stress-related behavior, physiological effects during pregnancy and parenting, and various cellular effects in neoplastic tissue. In this study, we aimed to unravel the underlying mechanism that OXT employs to regulate cell-cell contacts, spheroid formation, and cellular migration in a 3D culture model of human MLS-402 cells. We have generated a labeled OXT receptor (OXTR) overexpressing cell line cultivated in spheroids that were treated with the OXTR agonists OXT, Atosiban, and Thr4-Gly7-oxytocin (TGOT); with or without a pre-treatment of antisense oligos (Gapmers) that induce exon skipping in the human OXTR gene. This exon skipping leads to the exclusion of exon 4 and therefore a receptor that lost its intracellular G-protein-binding domain. Sensitive digital PCR (dPCR) provided us with the means to differentiate between wild type and truncated OXTR in our cellular model. OXTR truncation differentially activated intracellular signaling cascades related to cell-cell attachment and proliferation like Akt, ERK1/2-RSK1/2, HSP27, STAT1/5, and CREB, as assessed by a Kinase Profiler Assay. Digital and transmission electron microscopy revealed increased tight junction formation and well-organized cellular protrusions into an enlarged extracellular space after OXT treatment, resulting in increased cellular survival. In summary, OXT decreases cellular migration but increases cell-cell contacts and therefore improves nutrient supply. These data reveal a novel cellular effect of OXT that might have implications for degenerating CNS diseases and tumor formation in various tissues.

A perspective on molecular signalling dysfunction, its clinical relevance and therapeutics in autism spectrum disorder

Intellectual disability (ID) and autism spectrum disorder (ASD) are neurodevelopmental disorders that have become a primary clinical and social concern, with a prevalence of 2-3% in the population. Neuronal function and behaviour undergo significant malleability during the critical period of development that is found to be impaired in ID/ASD. Human genome sequencing studies have revealed many genetic variations associated with ASD/ID that are further verified by many approaches, including many mouse and other models. These models have facilitated the identification of fundamental mechanisms underlying the pathogenesis of ASD/ID, and several studies have proposed converging molecular pathways in ASD/ID. However, linking the mechanisms of the pathogenic genes and their molecular characteristics that lead to ID/ASD has progressed slowly, hampering the development of potential therapeutic strategies. This review discusses the possibility of recognising the common molecular causes for most ASD/ID based on studies from the available models that may enable a better therapeutic strategy to treat ID/ASD. We also reviewed the potential biomarkers to detect ASD/ID at early stages that may aid in diagnosis and initiating medical treatment, the concerns with drug failure in clinical trials, and developing therapeutic strategies that can be applied beyond a particular mutation associated with ASD/ID.

Oxytocin-based therapies for treatment of Prader-Willi and Schaaf-Yang syndromes: evidence, disappointments, and future research strategies

The prosocial neuropeptide oxytocin is being developed as a potential treatment for various neuropsychiatric disorders including autism spectrum disorder (ASD). Early studies using intranasal oxytocin in patients with ASD yielded encouraging results and for some time, scientists and affected families placed high hopes on the use of intranasal oxytocin for behavioral therapy in ASD. However, a recent Phase III trial obtained negative results using intranasal oxytocin for the treatment of behavioral symptoms in children with ASD. Given the frequently observed autism-like behavioral phenotypes in Prader-Willi and Schaaf-Yang syndromes, it is unclear whether oxytocin treatment represents a viable option to treat behavioral symptoms in these diseases. Here we review the latest findings on intranasal OT treatment, Prader-Willi and Schaaf-Yang syndromes, and propose novel research strategies for tailored oxytocin-based therapies for affected individuals. Finally, we propose the critical period theory, which could explain why oxytocin-based treatment seems to be most efficient in infants, but not adolescents.

Oxytocin and serotonin in the modulation of neural function: Neurobiological underpinnings of autism-related behavior

Autism spectrum disorders (ASD) is a group of generalized neurodevelopmental disorders. Its main clinical features are social communication disorder and repetitive stereotyped behavioral interest. The abnormal structure and function of brain network is the basis of social dysfunction and stereotyped performance in patients with autism spectrum disorder. The number of patients diagnosed with ASD has increased year by year, but there is a lack of effective intervention and treatment. Oxytocin has been revealed to effectively improve social cognitive function and significantly improve the social information processing ability, empathy ability and social communication ability of ASD patients. The change of serotonin level also been reported affecting the development of brain and causes ASD-like behavioral abnormalities, such as anxiety, depression like behavior, stereotyped behavior. Present review will focus on the research progress of serotonin and oxytocin in the pathogenesis, brain circuit changes and treatment of autism. Revealing the regulatory effect and neural mechanism of serotonin and oxytocin on patients with ASD is not only conducive to a deeper comprehension of the pathogenesis of ASD, but also has vital clinical significance.

SHANK3 deficiency leads to myelin defects in the central and peripheral nervous system

Mutations or deletions of the SHANK3 gene are causative for Phelan–McDermid syndrome (PMDS), a syndromic form of autism spectrum disorders (ASDs). We analyzed Shank3Δ11(−/−) mice and organoids from PMDS individuals to study effects on myelin. SHANK3 was found to be expressed in oligodendrocytes and Schwann cells, and MRI analysis of Shank3Δ11(−/−) mice revealed a reduced volume of the corpus callosum as seen in PMDS patients. Myelin proteins including myelin basic protein showed significant temporal and regional differences with lower levels in the CNS but increased amounts in the PNS of Shank3Δ11(−/−) animals. Node, as well as paranode, lengths were increased and ultrastructural analysis revealed region-specific alterations of the myelin sheaths. In PMDS hiPSC-derived cerebral organoids we observed an altered number and delayed maturation of myelinating cells. These findings provide evidence that, in addition to a synaptic deregulation, impairment of myelin might profoundly contribute to the clinical manifestation of SHANK3 deficiency.

Examining the effect of chronic intranasal oxytocin administration on the neuroanatomy and behavior of three autism-related mouse models

Although initially showing great potential, oxytocin treatment has encountered a translational hurdle in its promise of treating the social deficits of autism. Some debate surrounds the ability of oxytocin to successfully enter the brain, and therefore modify neuroanatomy. Moreover, given the heterogeneous nature of autism, treatment will only amerliorate symptoms in a subset of patients. Therefore, to determine whether oxytocin changes brain circuitry, and whether it does so variably, depending on genotype, we implemented a large randomized, blinded, placebo-controlled, preclinical study on chronic intranasal oxytocin treatment in three different mouse models related to autism with a focus on using neuroanatomical phenotypes to assess and subset treatment response. Intranasal oxytocin (0.6IU) was administered daily, for 28 days, starting at 5 weeks of age to the 16p11.2 deletion, Shank3 (exon 4-9) knockout, and Fmr1 knockout mouse models. Given the sensitivity of structural magnetic resonance imaging (MRI) to the neurological effects of interventions like drugs, along with many other advantages, the mice underwent in vivo longitudinal and high-resolution ex vivo imaging with MRI. The scans included three in vivo T1weighted, 90um isotropic resolution scans and a T2-weighted, 3D fast spin echo with 40um isotropic resolution ex vivo scan to assess the changes in neuroanatomy using established automated image registration and deformation based morphometry approaches in response to oxytocin treatment. The behavior of the mice was assessed in multiple domains, including social behaviours and repetitive behaviours, among others. Treatment effect on the neuroanatomy did not reach significance, although the pattern of trending effects was promising. No significant effect of treatment was found on social behavior in any of the strains, although a significant effect of treatment was found in the Fmr1 mouse, with treatment normalizing a grooming deficit. No other treatment effect on behavior was observed that survived multiple comparisons correction. Overall, chronic treatment with oxytocin had limited effects on the three mouse models related to autism, and no promising pattern of response susceptibility emerged.

Molecular brain (micro report) oxytocin ameliorates impaired social behavior in a mouse model of 3q29 deletion syndrome

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by specific social symptoms, restricted interests, stereotyped repetitive behaviors, and delayed language development. The 3q29 microdeletion (3q29del), a recurrent copy number variant, confers a high risk for ASD and schizophrenia, and serves as an important pathological model for investigating the molecular pathogenesis of a large number of neurodevelopmental and psychiatric conditions. Recently, mouse models carrying a deletion of the chromosomal region corresponding to the human 3q29 region (Df/+ mice) were generated and demonstrated neurodevelopmental and psychiatric conditions associated behavioral abnormalities, pointing to the relevance of Df/+ mice as a model for these conditions with high construct and face validity. Currently, the molecular pathogenesis of these behavioral phenotypes in Df/+ mice remains unclear. The oxytocin (OXT) system plays a central role in social behavior across species and has a potential role in ASD. In this study, to elucidate the molecular mechanisms behind impaired social behavior in Df/+ mice, we investigated the possible involvement of OXT signaling in impaired social behavior in Df/+ mice. We demonstrated that OXT administration restored the impaired social behavior in Df/+ mice. We also demonstrated that the number of OXT-positive cells in the paraventricular nucleus (PVN) was significantly lower in Df/+ mice than in wild-type (WT) littermates. Consistent with this, the level of OXT peptide in the cerebral cortex of Df/+ mice was lower than in WT littermates. Our study may provide important insights into the molecular pathophysiological basis of neurodevelopmental and psychiatric conditions, including ASD.

Transcriptome Analysis in Hippocampus of Rats Prenatally Exposed to Valproic Acid and Effects of Intranasal Treatment of Oxytocin

Autism spectrum disorder (ASD) is a heterogeneous disorder characterized by repetitive behaviors and social impairments, often accompanied by learning disabilities. It has been documented that the neuropeptide oxytocin (OXT) ameliorates core symptoms in patients with ASD. We recently reported that chronic administration of intranasal OXT reversed social and learning impairments in prenatally valproic acid (VPA)-exposed rats. However, the underlying molecular mechanisms remain unclear. Here, we explored molecular alterations in the hippocampus of rats and the effects of chronic administration of intranasal OXT (12 μg/kg/d). Microarray analyses revealed that prenatal VPA exposure altered gene expression, a part of which is suggested as a candidate in ASD and is involved in key features including memory, developmental processes, and epilepsy. OXT partly improved the expression of these genes, which were predicted to interact with those involved in social behaviors and hippocampal-dependent memory. Collectively, the present study documented molecular profiling in the hippocampus related to ASD and improvement by chronic treatment with OXT.

Gene expression levels of DNA methyltransferase enzymes in Shank3-deficient mouse model of autism during early development

Objectives. The balance between DNA methylation and demethylation is crucial for the brain development. Therefore, alterations in the expression of enzymes controlling DNA methylation patterns may contribute to the etiology of neurodevelopmental disorders, including autism. SH3 and multiple ankyrin repeat domains 3 (Shank3)-deficient mice are commonly used as a well-characterized transgenic model to investigate the molecular mechanisms of autistic symptoms. DNA methyltransferases (DNMTs), which modulate several cellular processes in neurodevelopment, are implicated in the pathophysiology of autism. In this study, we aimed to describe the gene expression changes of major Dnmts in the brain of Shank3-deficient mice during early development. Methods and Results. The Dnmts gene expression was analyzed by qPCR in 5-day-old homo-zygous Shank3-deficient mice. We found significantly lower Dnmt1 and Dnmt3b gene expression levels in the frontal cortex. However, no such changes were observed in the hippocampus. However, significant increase was observed in the expression of Dnmt3a and Dnmt3b genes in the hypothalamus of Shank3-deficient mice. Conclusions. The present data indicate that abnormalities in the Shank3 gene are accompanied by an altered expression of DNA methylation enzymes in the early brain development stages, therefore, specific epigenetic control mechanisms in autism-relevant models should be more extensively investigated.

Oxytocin system driven by experiences modifies social recognition and neuron morphology in female BALB/c mice

The oxytocin (OT) system, affected by life experiences, modulates neuron morphology in a sex-specific manner, leading to sex differences in social interactions. To date, few studies have focused on the OT system and social interactions of female mice. In this study, we used maternal deprivation (MD) and its possible treatment, environmental enrichment (EE), to affect social recognition in female BALB/c mice. We checked neuron morphology, synaptic connections, oxytocinergic (OTergic) neurons in the hypothalamus paraventricular nucleus (PVH), and OT receptor (OTR) in the basolateral amygdala (BLA) and layer II/III of the prelimbic cortex (PL). Our results showed that MD induced social recognition impairments, increased OTR levels in the BLA, and, meanwhile, reduced OTergic neurons in the magnocellular region of the PVH (mPVH). Decreased Nissl bodies, increased cell nuclei, and increased dendrites of projection neurons paralleled the increased OTR levels in the BLA of MD mice. EE restored MD-induced the impairments of novel object recognition and sociability; this effect paralleled a decrease in cell density in the PL and an increase in OTergic neurons in the parvocellular regions of the PVH and synaptic connections in the BLA and layer II/III of the PL. Our findings indicate that early life stress such as MD impairs social recognition, and meanwhile, remodels neuron morphology region-specifically in the female brain, apparently in the BLA but slightly in the PL; and EE could partially restore the deficits induced by MD. The results provide new insights into sex differences in the prevalence of psychological development disorders.

A randomized controlled trial of intranasal oxytocin in Phelan-McDermid syndrome

Background

Phelan-McDermid syndrome (PMS) is a rare neurodevelopmental disorder caused by haploinsufficiency of the SHANK3 gene and characterized by global developmental delays, deficits in speech and motor function, and autism spectrum disorder (ASD). Monogenic causes of ASD such as PMS are well suited to investigations with novel therapeutics, as interventions can be targeted based on established genetic etiology. While preclinical studies have demonstrated that the neuropeptide oxytocin can reverse electrophysiological, attentional, and social recognition memory deficits in Shank3-deficient rats, there have been no trials in individuals with PMS. The purpose of this study is to assess the efficacy and safety of intranasal oxytocin as a treatment for the core symptoms of ASD in a cohort of children with PMS.

Methods

Eighteen children aged 5–17 with PMS were enrolled. Participants were randomized to receive intranasal oxytocin or placebo (intranasal saline) and underwent treatment during a 12-week double-blind, parallel group phase, followed by a 12-week open-label extension phase during which all participants received oxytocin. Efficacy was assessed using the primary outcome of the Aberrant Behavior Checklist-Social Withdrawal (ABC-SW) subscale as well as a number of secondary outcome measures related to the core symptoms of ASD. Safety was monitored throughout the study period.

Results

There was no statistically significant improvement with oxytocin as compared to placebo on the ABC-SW (Mann–Whitney U = 50, p = 0.055), or on any secondary outcome measures, during either the double-blind or open-label phases. Oxytocin was generally well tolerated, and there were no serious adverse events.

Limitations

The small sample size, potential challenges with drug administration, and expectancy bias due to relying on parent reported outcome measures may all contribute to limitations in interpreting results.

Conclusion

Our results suggest that intranasal oxytocin is not efficacious in improving the core symptoms of ASD in children with PMS.

Trial registration NCT02710084.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00459-1.

Shank3 Deficiency is Associated With Altered Profile of Neurotransmission Markers in Pups and Adult Mice

Alterations in the balance between excitation and inhibition, especially in the brain's critical developmental periods, are considered an integral part of the pathophysiology of autism. However, the precise mechanisms have not yet been established. SH3 and multiple Ankyrin repeat domains 3 (Shank3) deficient mice represent a well-established transgenic model of a neurodevelopmental disorder with autistic symptomatology. In this study, we characterize the consequences of Shank3 deficiency according to (1) expression of specific markers of different neuronal populations in pups and adult mice and (2) social behaviour and anxiety in adult mice. Our research found enhanced expression of serotonin transporter and choline acetyltransferase in the hippocampus and hypothalamus in Shank3-deficient pups. We demonstrated marked brain region differences in expression of excitatory glutamatergic markers in pups and adult Shank3 deficient mice. We also observed reduced expression of inhibitory GABAergic markers and GABA receptor subunits in several brain areas in both pups and adult Shank3 deficient mice. Further analysis of dopaminergic brain areas (nucleus accumbens, ventral tegmental area) revealed lower expression levels of GABAergic markers in adult Shank3 deficient mice. Adult Shank3^- deficient mice exhibited excessive repetitive behaviour, a higher level of anxiety, and lower locomotor activity. Our data support the theory of an imbalance between excitatory and inhibitory neurotransmission in conditions of abnormal SHANK3 protein. We therefore suggest that autism-like conditions are accompanied by reduced expression of GABAergic markers in the brain during early development as well as in the adult age, which could be associated with long-lasting behavioural abnormalities.

The effects of testosterone on gene expression of cell-adhesion molecules and scaffolding proteins: The role of sex in early development

Sex-specific differences in brain plasticity appear to be organised by testosterone, which is particularly important during the early stages of development. The main purpose of the present study was to examine the sex differences in mRNA and protein levels of selected cell-adhesion molecules and scaffolding proteins on postnatal days 5 (P5) and 9 (P9) in the rat hippocampus, as well as evaluate the effects of testosterone treatment (100 nM, 48 hr) on synaptic proteins in SH-SY5Y (neuron-like) and U-87MG (astrocyte-like) cells. The gene expression levels of Neuroligin 3 and 'SH3 and multiple ankyrin repeat domains protein' 1 and 3 (SHANK1 and SHANK3) were significantly lower in males compared to females at P5. At P9, a similar significant trend towards a decrease in mRNA expression and protein levels of SHANK3 was found in males. Testosterone treatment induced a significant decrease of Neuroligin 1-3 mRNA expression in both SH-SY5Y and U-87MG cells. SHANK1 and SHANK3 mRNA levels significantly decreased in U-87MG cells response to testosterone presence. The presented results demonstrate that the association of selected postsynaptic cell-adhesion molecules and scaffolding proteins is sex-related. Testosterone appears to be particularly involved in the developmental mechanisms related to neuroplasticity.

The epigenetic regulation of synaptic genes contributes to the etiology of autism

Epigenetic mechanisms greatly affect the developing brain, as well as the maturation of synapses with pervasive, long-lasting consequences on behavior in adults. Substantial evidence exists that implicates dysregulation of epigenetic mechanisms in the etiology of neurodevelopmental disorders. Therefore, this review explains the role of enzymes involved in DNA methylation and demethylation in neurodevelopment by emphasizing changes of synaptic genes and proteins. Epigenetic causes of sex-dependent differences in the brain are analyzed in conjunction with the pathophysiology of autism spectrum disorders. Special attention is devoted to the epigenetic regulation of the melanoma-associated antigen-like gene 2 (MAGEL2) found in Prader-Willi syndrome, which is known to be accompanied by autistic symptoms.