Plasma oxytocin levels in autistic children

Administration of Atosiban, an oxytocin receptor antagonist, ameliorates autistic-like behaviors in a female rat model of valproic acid-induced autism

Autism spectrum disorder (ASD) is a pervasive developmental disorder with gender differences. Oxytocin (OXT) is currently an important candidate drug for autism, but the lack of data on female autism is a big issue. It has been reported that the effect of OXT is likely to be different between male and female ASD patients. In the study, we specifically explored the role of the OXT signaling pathway in a VPA-induced female rat's model of autism. The data showed that there was an increase of either oxytocin or its receptor expressions in both the hippocampus and the prefrontal cortex of VPA-induced female offspring. To determine if the excess of OXT signaling contributed to autism symptoms in female rats, exogenous oxytocin and oxytocin receptor antagonists Atosiban were used in the experiment. It was found that exogenous oxytocin triggered autism-like behaviors in wild-type female rats by intranasal administration. More interestingly, several autism-like deficits including social interaction, anxiety, and repeat stereotypical sexual behavior in the VPA female offspring were significantly attenuated by oxytocin receptor antagonists Atosiban. Moreover, Atosiban also effectively improved the synaptic plasticity impairment induced by VPA in female offspring. Our results suggest that oxytocin receptor antagonists significantly improve autistic-like behaviors in a female rat model of valproic acid-induced autism.

Neuropeptides affecting social behavior in mammals: Oxytocin

Oxytocin (OXT), a neuropeptide consisting of only nine amino acids, is synthesized in the paraventricular and supraoptic nuclei of the hypothalamus. Although OXT is best known for its role in lactation and parturition, recent research has shown that it also has a significant impact on social behaviors in mammals. However, a comprehensive review of this topic is still lacking. In this paper, we systematically reviewed the effects of OXT on social behavior in mammals. These effects of OXT from the perspective of five key behavioral dimensions were summarized: parental behavior, anxiety, aggression, attachment, and empathy. To date, researchers have agreed that OXT plays a positive regulatory role in a wide range of social behaviors, but there have been controversially reported results. In this review, we have provided a detailed panorama of the role of OXT in social behavior and, for the first time, delved into the underlying regulatory mechanisms, which may help better understand the multifaceted role of OXT. Levels of OXT in previous human studies were also summarized to provide insights for diagnosis of mental disorders.

Animal-assisted therapy in pediatric autism spectrum disorder: A case report

ABSTRACT

The use of therapy or service dogs to assist children with autism spectrum disorder (ASD) is increasing in clinical settings. Research studies indicate that children with ASD display enhanced prosocial behavior and emotional regulation when canines are included in therapy. Despite increased application of animal-assisted therapy in clinical and inpatient settings, healthcare providers show limited understanding of best practices for its use and require a research-based approach to incorporate animals effectively into therapeutic plans of care for pediatric patients with ASD.

Between Dysbiosis, Maternal Immune Activation and Autism: Is There a Common Pathway?

Autism spectrum disorder (ASD) is a neuropsychiatric condition characterized by impaired social interactions and repetitive stereotyped behaviors. Growing evidence highlights an important role of the gut-brain-microbiome axis in the pathogenesis of ASD. Research indicates an abnormal composition of the gut microbiome and the potential involvement of bacterial molecules in neuroinflammation and brain development disruptions. Concurrently, attention is directed towards the role of short-chain fatty acids (SCFAs) and impaired intestinal tightness. This comprehensive review emphasizes the potential impact of maternal gut microbiota changes on the development of autism in children, especially considering maternal immune activation (MIA). The following paper evaluates the impact of the birth route on the colonization of the child with bacteria in the first weeks of life. Furthermore, it explores the role of pro-inflammatory cytokines, such as IL-6 and IL-17a and mother's obesity as potentially environmental factors of ASD. The purpose of this review is to advance our understanding of ASD pathogenesis, while also searching for the positive implications of the latest therapies, such as probiotics, prebiotics or fecal microbiota transplantation, targeting the gut microbiota and reducing inflammation. This review aims to provide valuable insights that could instruct future studies and treatments for individuals affected by ASD.

The Pivotal Role of Oxytocin's Mechanism of Thermoregulation in Prader-Willi Syndrome, Schaaf-Yang Syndrome, and Autism Spectrum Disorder

Oxytocin (Oxt) regulates thermogenesis, and altered thermoregulation results in Prader-Willi syndrome (PWS), Schaaf-Yang syndrome (SYS), and Autism spectrum disorder (ASD). PWS is a genetic disorder caused by the deletion of the paternal allele of 15q11-q13, the maternal uniparental disomy of chromosome 15, or defects in the imprinting center of chromosome 15. PWS is characterized by hyperphagia, obesity, low skeletal muscle tone, and autism spectrum disorder (ASD). Oxt also increases muscle tonicity and decreases proteolysis while PWS infants are hypotonic and require assisted feeding in early infancy. This evidence inspired us to merge the results of almost 20 years of studies and formulate a new hypothesis according to which the disruption of Oxt's mechanism of thermoregulation manifests in PWS, SYS, and ASD through thermosensory abnormalities and skeletal muscle tone. This review will integrate the current literature with new updates on PWS, SYS, and ASD and the recent discoveries on Oxt's regulation of thermogenesis to advance the knowledge on these diseases.

Peripheral oxytocin levels are linked to hypothalamic gray matter volume in autistic adults: a cross-sectional secondary data analysis

Oxytocin (OXT) is known to modulate social behavior and cognition and has been discussed as pathophysiological and therapeutic factor for autism spectrum disorder (ASD). An accumulating body of evidence indicates the hypothalamus to be of particular importance with regard to the underlying neurobiology. Here we used a region of interest voxel-based morphometry (VBM) approach to investigate hypothalamic gray matter volume (GMV) in autistic (n = 29, age 36.03 ± 11.0) and non-autistic adults (n = 27, age 30.96 ± 11.2). Peripheral plasma OXT levels and the autism spectrum quotient (AQ) were used for correlation analyses. Results showed no differences in hypothalamic GMV in autistic compared to non-autistic adults but suggested a differential association between hypothalamic GMV and OXT levels, such that a positive association was found for the ASD group. In addition, hypothalamic GMV showed a positive association with autistic traits in the ASD group. Bearing in mind the limitations such as a relatively small sample size, a wide age range and a high rate of psychopharmacological treatment in the ASD sample, these results provide new preliminary evidence for a potentially important role of the HTH in ASD and its relationship to the OXT system, but also point towards the importance of interindividual differences.

[Biochemical markers of autism]

Autism spectrum disorder (ASD) is becoming an increasingly common disorder of the development of the nervous system in the modern world. The diagnosis is made based on observation of the patient's behavior, which significantly complicates the diagnosis and treatment of the disorder. The subjectivity of behavioral diagnostics dictates the need for the study of biomarkers of ASD. Over the past two decades, researchers have focused on identifying specific biological abnormalities in ASD that will help in the diagnosis of the disease. This review discusses the state of research on various biomarkers currently being developed for ASD.

Detection, processing and reinforcement of social cues: regulation by the oxytocin system

Many social behaviours are evolutionarily conserved and are essential for the healthy development of an individual. The neuropeptide oxytocin (OXT) is crucial for the fine-tuned regulation of social interactions in mammals. The advent and application of state-of-the-art methodological approaches that allow the activity of neuronal circuits involving OXT to be monitored and functionally manipulated in laboratory mammals have deepened our understanding of the roles of OXT in these behaviours. In this Review, we discuss how OXT promotes the sensory detection and evaluation of social cues, the subsequent approach and display of social behaviour, and the rewarding consequences of social interactions in selected reproductive and non-reproductive social behaviours. Social stressors - such as social isolation, exposure to social defeat or social trauma, and partner loss - are often paralleled by maladaptations of the OXT system, and restoring OXT system functioning can reinstate socio-emotional allostasis. Thus, the OXT system acts as a dynamic mediator of appropriate behavioural adaptations to environmental challenges by enhancing and reinforcing social salience and buffering social stress.

The use of intranasal oxytocin in the treatment of eating disorders

Oxytocin (OXT) is a hypothalamic peptide that plays a number of roles in the body, being involved in labor and lactation, as well as cognitive-emotional processes and social behavior. In recent years, knowledge of the physiology of OXT has been repeatedly used to explore its potential role in the treatment of numerous diseases, identifying a significant role for OXT in appetite regulation, eating behavior, weight regulation, and food-related beliefs. In this review we provide an overview of publications on this topic, but due to the wealth of research, we have limited our focus to studies based on the use of intranasal OXT in psychiatric diseases, with a particular focus on the role of oxytocin in eating disorders and obesity. Accumulating evidence that OXT intranasal supplementation may provide some therapeutic benefit seems promising. In individuals with autistic spectrum disorders (ASD) and schizophrenia, OXT may affect core deficits, improving social cognition and reducing symptom severity in schizophrenia. Dysregulation of serum and CSF OXT levels, as well as polymorphisms of its genes, may affect emotion perception in patients with eating disorders and correlate with co-occurring depressive and anxiety disorders. Nevertheless, there are still many critical questions regarding the pharmacokinetics and pharmacodynamics of intranasal OXT that can only be answered in larger randomized controlled trials.

Tales from the life and lab of a female social neuroscientist

This narrative review charts my unconventional path to becoming a social neuroscientist and describes my research findings - some baffling, some serendipitous, some pivotal - in the field of neuropeptide biology. I trace my childhood as a Bell Labs "brat" to my adolescence as a soccer-playing party girl, to my early days as a graduate student, when I first encountered oxytocin and vasopressin. These two molecules instantly captivated - and held - my attention and imagination. For more than 25 years, a core goal of my research program has been to better understand how these neuropeptides regulate social functioning across a range of species (e.g., meadow voles, mice, squirrel monkeys, rhesus monkeys, and humans), and to translate fundamental insights from this work to guide development of novel pharmacotherapies to treat social impairments in clinical populations. I also discuss my experience of being a woman and a mother in STEM, and identify the important people and events which helped shape my career and the scientist I am today.

Microbes, oxytocin and stress: Converging players regulating eating behavior

Oxytocin is a peptide-hormone extensively studied for its multifaceted biological functions and has recently gained attention for its role in eating behavior, through its action as an anorexigenic neuropeptide. Moreover, the gut microbiota is involved in oxytocinergic signaling through the brain-gut axis, specifically in the regulation of social behavior. The gut microbiota is also implicated in appetite regulation and is postulated to play a role in central regulation of hedonic eating. In this review, we provide an overview on oxytocin and its individual links with the microbiome, the homeostatic and non-homeostatic regulation of eating behavior as well as social behavior and stress.

Association between Neuroligin-1 polymorphism and plasma glutamine levels in individuals with autism spectrum disorder

BACKGROUND

Unravelling the relationships between candidate genes and autism spectrum disorder (ASD) phenotypes remains an outstanding challenge. Endophenotypes, defined as inheritable, measurable quantitative traits, might provide intermediary links between genetic risk factors and multifaceted ASD phenotypes. In this study, we sought to determine whether plasma metabolite levels could serve as endophenotypes in individuals with ASD and their family members.

METHODS

We employed an untargeted, high-resolution metabolomics platform to analyse 14,342 features across 1099 plasma samples. These samples were collected from probands and their family members participating in the Autism Genetic Resource Exchange (AGRE) (N = 658), compared with neurotypical individuals enrolled in the PrecisionLink Health Discovery (PLHD) program at Boston Children's Hospital (N = 441). We conducted a metabolite quantitative trait loci (mQTL) analysis using whole-genome genotyping data from each cohort in AGRE and PLHD, aiming to prioritize significant mQTL and metabolite pairs that were exclusively observed in AGRE.

FINDINGS

Within the AGRE group, we identified 54 significant associations between genotypes and metabolite levels (P < 5.27 × 10-11), 44 of which were not observed in the PLHD group. Plasma glutamine levels were found to be associated with variants in the NLGN1 gene, a gene that encodes post-synaptic cell-adhesion molecules in excitatory neurons. This association was not detected in the PLHD group. Notably, a significant negative correlation between plasma glutamine and glutamate levels was observed in the AGRE group, but not in the PLHD group. Furthermore, plasma glutamine levels showed a negative correlation with the severity of restrictive and repetitive behaviours (RRB) in ASD, although no direct association was observed between RRB severity and the NLGN1 genotype.

INTERPRETATION

Our findings suggest that plasma glutamine levels could potentially serve as an endophenotype, thus establishing a link between the genetic risk associated with NLGN1 and the severity of RRB in ASD. This identified association could facilitate the development of novel therapeutic targets, assist in selecting specific cohorts for clinical trials, and provide insights into target symptoms for future ASD treatment strategies.

FUNDING

This work was supported by the National Institute of Health (grant numbers: R01MH107205, U01TR002623, R24OD024622, OT2OD032720, and R01NS129188) and the PrecisionLink Biobank for Health Discovery at Boston Children's Hospital.

Salivary Oxytocin and Antioxidative Response to Robotic Touch in Adults with Autism Spectrum Disorder

Individuals with ASD are known to have a tendency to have tactile sensory processing issues that could be associated with their impairment as regards social communication. The alterations in tactile processing in autistic subjects are usually accompanied by hypersensitivity and other unpleasant emotions induced by tactile contact. In our study, we investigated the impact of the velocity and the force of a tactile stroke received impersonally by a custom-built robotic device. A total of 21 adults with ASD and 22 adults from a control group participated in our study. The participants' responses were assessed according to subjective scales, EEG changes, and the dynamics of saliva antioxidants and oxytocin. It was found that the oxytocin level was significantly lower in subjects with ASD but increased after tactile stimulation. However, contrary to expectations, the increase in the oxytocin level in the target group negatively correlated with the subjective pleasantness of tactile stimulation and was probably associated with a stress-induced effect. The basic levels of antioxidants did not differ between the TD and ASD groups; however, these had significantly increased in individuals with ASD by the end of the study. The EEG findings, which revealed enhanced antioxidant levels, contributed to the relief of the cognitive control during the study.

Genetic and epigenetic signatures associated with plasma oxytocin levels in children and adolescents with autism spectrum disorder

Oxytocin (OT), the brain's most abundant neuropeptide, plays an important role in social salience and motivation. Clinical trials of the efficacy of OT in autism spectrum disorder (ASD) have reported mixed results due in part to ASD's complex etiology. We investigated whether genetic and epigenetic variation contribute to variable endogenous OT levels that modulate sensitivity to OT therapy. To carry out this analysis, we integrated genome-wide profiles of DNA-methylation, transcriptional activity, and genetic variation with plasma OT levels in 290 participants with ASD enrolled in a randomized controlled trial of OT. Our analysis identified genetic variants with novel association with plasma OT, several of which reside in known ASD risk genes. We also show subtle but statistically significant association of plasma OT levels with peripheral transcriptional activity and DNA-methylation profiles across several annotated gene sets. These findings broaden our understanding of the effects of the peripheral oxytocin system and provide novel genetic candidates for future studies to decode the complex etiology of ASD and its interaction with OT signaling and OT-based interventions. LAY SUMMARY: Oxytocin (OT) is an abundant chemical produced by neurons that plays an important role in social interaction and motivation. We investigated whether genetic and epigenetic factors contribute to variable OT levels in the blood. To this, we integrated genetic, gene expression, and non-DNA regulated (epigenetic) signatures with blood OT levels in 290 participants with autism enrolled in an OT clinical trial. We identified genetic association with plasma OT, several of which reside in known autism risk genes. We also show statistically significant association of plasma OT levels with gene expression and epigenetic across several gene pathways. These findings broaden our understanding of the factors that influence OT levels in the blood for future studies to decode the complex presentation of autism and its interaction with OT and OT-based treatment.

Reading the room: Autistic traits, gaze behaviour, and the ability to infer social relationships

Individuals high in autistic traits can have difficulty understanding verbal and non-verbal cues, and may display atypical gaze behaviour during social interactions. The aim of this study was to examine differences among neurotypical individuals with high and low levels of autistic traits with regard to their gaze behaviour and their ability to assess peers' social status accurately. Fifty-four university students who completed the 10-item Autism Quotient (AQ-10) were eye-tracked as they watched six 20-second video clips of people ("targets") involved in a group decision-making task. Simulating natural, everyday social interactions, the video clips included moments of debate, humour, interruptions, and cross talk. Results showed that high-scorers on the AQ-10 (i.e., those with more autistic traits) did not differ from the low-scorers in either gaze behaviour or assessing the targets' relative social status. The results based on this neurotypical group of participants suggest that the ability of individuals high in autistic traits to read social cues may be preserved in certain tasks crucial to navigating day-to-day social relationships. These findings are discussed in terms of their implications for theory of mind, weak central coherence, and social motivation theories of autism.

The association between autistic traits and serum testosterone, oxytocin, and androstenedione levels in prepubertal male drug naive children with attention-deficit/hyperactivity disorder

BACKGROUND

Children with attention-deficit/hyperactivity disorder (ADHD) might have similar problems as in autism spectrum disorder (ASD) and show impairment in social behaviour. Also, there is a relationship between social relationship skills and ToM (theory of mind) skills of children with ADHD. Besides, ASD is associated with prenatal exposure to high levels of androgens, and oxytocin plays a role in the modulation of emotions, coping with stress, and social behaviour like ASD. In this study, the relationship between autistic traits and serum oxytocin, testosterone, and androstenedione levels in prepubertal male drug naive children with ADHD has been investigated.

METHOD

Eighty-three prepubertal children, who were diagnosed with ADHD between the ages of 6-10 years old, are included in the study. For the study, intelligence levels were evaluated by using WISC-4, and autistic traits were measured by using both social responsiveness scale and theory of mind tests. In addition, serum oxytocin, testosterone, and androstenedione levels were measured by using ELISA.

RESULTS

It has been found that serum testosterone levels of patients with lower autistic traits are significantly lower than those with moderate and severe autistic traits, while the serum oxytocin levels are significantly higher. Also, patients with severe autistic traits have had significantly higher serum androstenedione levels than those with lower and moderate autistic traits.

CONCLUSION

This study suggests that patients who have higher autistic traits have elevated testosterone and androstenedione levels and lower serum oxytocin levels. Further studies are needed to clarify this relationship.

Saliva based diagnostic methodologies for a fast track detection of autism spectrum disorder: A mini-review

Autism spectrum disorder (ASD) is considered a complicated neurodevelopment disorder with rising prevalence globally. ASD is characterized by a series of events including varying degrees of defects in communication, learning, and social interaction which is accompanied by stereotypical behavioral patterns. Despite extensive research, the current diagnosis for ASD is complex and almost solely based on the behavioral assessments of the suspected individuals. The multifactorial etiopathology of this disease along with the diversity of symptoms among different individuals adds to the current intricacies for accurate prognosis of ASD. Hence, there exists a dire need for biologically relevant biomarkers for an early diagnosis and for tracking the efficacy of therapeutic interventions. Until recently, among various biofluids, saliva has gained increasing interest for biomarker identification, the advantages include the non-invasive nature and ease of sample handling. This mini-review aims to provide a succinct summary of recent literature on saliva-based diagnostic modalities for ASD, examine various studies that highlight the potential use of proteomic and/or RNA-based biomarkers. Finally, some conclusive perspectives of using the salivary system for ASD mechanistic details and diagnosis are also discussed.

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—a social peptide? Deconstructing the evidence

In this paper, we analyse the claim that oxytocin is a ‘social neuropeptide’. This claim originated from evidence that oxytocin was instrumental in the initiation of maternal behaviour and it was extended to become the claim that oxytocin has a key role in promoting social interactions between individuals. We begin by considering the structure of the scientific literature on this topic, identifying closely interconnected clusters of papers on particular themes. We then analyse this claim by considering evidence of four types as generated by these clusters: (i) mechanistic studies in animal models, designed to understand the pathways involved in the behavioural effects of centrally administered oxytocin; (ii) evidence from observational studies indicating an association between oxytocin signalling pathways and social behaviour; (iii) evidence from intervention studies, mainly involving intranasal oxytocin administration; and (iv) evidence from translational studies of patients with disorders of social behaviour. We then critically analyse the most highly cited papers in each segment of the evidence; we conclude that, if these represent the best evidence, then the evidence for the claim is weak.

This article is part of the theme issue ‘Interplays between oxytocin and other neuromodulators in shaping complex social behaviours’.

Oxytocin: An Old Hormone, A Novel Psychotropic Drug And Possible Use In Treating Psychiatric Disorders

BACKGROUND

Oxytocin is a nonapeptide synthesized in the paraventricular and supraoptic nuclei of the hypothalamus. Historically, this molecule has been involved as a key factor in the formation of infant attachment, maternal behavior and pair bonding and, more generally, in linking social signals with cognition, behaviors and reward. In the last decades, the whole oxytocin system has gained a growing interest as it was proposed to be implicated in etiopathogenesis of several neurodevelopmental and neuropsychiatric disorders.

METHODS

With the main goal of an in-depth understanding of the oxytocin role in the regulation of different functions and complex behaviors as well as its intriguing implications in different neuropsychiatric disorders, we performed a critical review of the current state of art. We carried out this work through PubMed database up to June 2021 with the search terms: 1) "oxytocin and neuropsychiatric disorders"; 2) "oxytocin and neurodevelopmental disorders"; 3) "oxytocin and anorexia"; 4) "oxytocin and eating disorders"; 5) "oxytocin and obsessive-compulsive disorder"; 6) "oxytocin and schizophrenia"; 7) "oxytocin and depression"; 8) "oxytocin and bipolar disorder"; 9) "oxytocin and psychosis"; 10) "oxytocin and anxiety"; 11) "oxytocin and personality disorder"; 12) "oxytocin and PTSD".

RESULTS

Biological, genetic, and epigenetic studies highlighted quality and quantity modifications in the expression of oxytocin peptide or in oxytocin receptor isoforms. These alterations would seem to be correlated with a higher risk of presenting several neuropsychiatric disorders belonging to different psychopathological spectra. Collaterally, the exogenous oxytocin administration has shown to ameliorate many neuropsychiatric clinical conditions.

CONCLUSION

Finally, we briefly analyzed the potential pharmacological use of oxytocin in patient with severe symptomatic SARS-CoV-2 infection due to its anti-inflammatory, anti-oxidative and immunoregulatory properties.

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.

Integrative analysis prioritised oxytocin-related biomarkers associated with the aetiology of autism spectrum disorder

Background

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with high phenotypic and genetic heterogeneity. The common variants of specific oxytocin-related genes (OTRGs), particularly OXTR, are associated with the aetiology of ASD. The contribution of rare genetic variations in OTRGs to ASD aetiology remains unclear.

Methods

We catalogued publicly available de novo mutations (DNMs) [from 6,511 patients with ASD and 3,391 controls], rare inherited variants (RIVs) [from 1,786 patients with ASD and 1,786 controls], and both de novo copy number variations (dnCNVs) and inherited CNVs (ihCNVs) [from 15,581 patients with ASD and 6,017 controls] in 963 curated OTRGs to explore their contribution to ASD pathology, respectively. Finally, a combined model was designed to prioritise the contribution of each gene to ASD aetiology by integrating DNMs and CNVs.

Findings

The rare genetic variations of OTRGs were significantly associated with ASD aetiology, in the order of dnCNVs > ihCNVs > DNMs. Furthermore, 172 OTRGs and their connected 286 ASD core genes were prioritised to positively contribute to ASD aetiology, including top-ranked MAPK3. Probands carrying rare disruptive variations in these genes were estimated to account for 10∼11% of all ASD probands.

Interpretation

Our findings suggest that rare disruptive variations in 172 OTRGs and their connected 286 ASD core genes are associated with ASD aetiology and may be potential biomarkers predicting the effects of oxytocin treatment.

Funding

Guangdong Key Project, National Natural Science Foundation of China, Key Laboratory of Clinical Laboratory Diagnosis and Translational Research of Zhejiang Province.

Genetics of autism spectrum disorder: an umbrella review of systematic reviews and meta-analyses

Autism spectrum disorder (ASD) is a class of neurodevelopmental conditions with a large epidemiological and societal impact worldwide. To date, numerous studies have investigated the associations between genetic variants and ASD risk. To provide a robust synthesis of published evidence of candidate gene studies for ASD, we performed an umbrella review (UR) of meta-analyses of genetic studies for ASD (PROSPERO registration number: CRD42021221868). We systematically searched eight English and Chinese databases from inception to March 31, 2022. Reviewing of eligibility, data extraction, and quality assessment were performed by two authors. In total, 28 of 5062 retrieved articles were analyzed, which investigated a combined 41 single nucleotide polymorphisms (SNPs) of nine candidate genes. Overall, 12 significant SNPs of CNTNAP2, MTHFR, OXTR, SLC25A12, and VDR were identified, of which associations with suggestive evidence included the C677T polymorphism of MTHFR (under allelic, dominant, and heterozygote models) and the rs731236 polymorphism of VDR (under allelic and homozygote models). Associations with weak evidence included the rs2710102 polymorphism of CNTNAP2 (under allelic, homozygote, and recessive models), the rs7794745 polymorphism of CNTNAP2 (under dominant and heterozygote models), the C677T polymorphism of MTHFR (under homozygote model), and the rs731236 polymorphism of VDR (under dominant and recessive models). Our UR summarizes research evidence on the genetics of ASD and provides a broad and detailed overview of risk genes for ASD. The rs2710102 and rs7794745 polymorphisms of CNTNAP2, C677T polymorphism of MTHFR, and rs731236 polymorphism of VDR may confer ASD risks. This study will provide clinicians and healthcare decision-makers with evidence-based information about the most salient candidate genes relevant to ASD and recommendations for future treatment, prevention, and research.

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.

Positron Emission Tomography in the Neuroimaging of Autism Spectrum Disorder: A Review

Autism spectrum disorder (ASD) is a basket term for neurodevelopmental disorders characterized by marked impairments in social interactions, repetitive and stereotypical behaviors, and restricted interests and activities. Subtypes include (A) disorders with known genetic abnormalities including fragile X syndrome, Rett syndrome, and tuberous sclerosis and (B) idiopathic ASD, conditions with unknown etiologies. Positron emission tomography (PET) is a molecular imaging technology that can be utilized in vivo for dynamic and quantitative research, and is a valuable tool for exploring pathophysiological mechanisms, evaluating therapeutic efficacy, and accelerating drug development in ASD. Recently, several imaging studies on ASD have been published and physiological changes during ASD progression was disclosed by PET. This paper reviews the specific radioligands for PET imaging of critical biomarkers in ASD, and summarizes and discusses the similar and different discoveries in outcomes of previous studies. It is of great importance to identify general physiological changes in cerebral glucose metabolism, cerebral blood flow perfusion, abnormalities in neurotransmitter systems, and inflammation in the central nervous system in ASD, which may provide excellent points for further ASD research.

The salience of competing nonsocial objects reduces gaze toward social stimuli, but not the eyes, more in typically developing than autistic boys

Decreased attention to social information is considered an early emerging symptom of autism spectrum disorder (ASD), although the underlying causes remain controversial. Here we explored the impact of nonsocial object salience on reduced attention to social stimuli in male ASD compared with typically developing (TD) children. Correlations with blood concentrations of neuropeptides linked with social cognition were also investigated. Eye-tracking was performed in 102 preschool-aged boys (50 ASD, 52 TD) using a paradigm with social (faces) versus nonsocial (objects) stimuli presented in pairs in two conditions where nonsocial stimulus salience was varied. Basal oxytocin (OXT) and vasopressin concentrations were measured in blood. Compared with TD boys those with ASD viewed social stimuli less only when they were paired with low-salience nonsocial objects. Additionally, boys with ASD spent less time than TD ones viewing facial features, particularly the eyes. In TD boys, OXT concentrations and cognitive development scores were positively associated with time spent viewing the eye region, whereas for boys with ASD associations with time spent viewing faces were negative. Reduced gaze toward social stimuli in ASD relative to TD individuals may therefore be influenced by how salient the paired nonsocial objects are for the latter. On the other hand, reduced interest in the eyes of faces in boys with ASD is not influenced by how salient competing nonsocial stimuli are. Basal OXT concentrations and cognitive development scores are predictive of time spent viewing social stimuli in TD boys (eyes) and those with ASD (faces) but in the opposite direction. LAY SUMMARY: Children with autism exhibit reduced attention to social paired with nonsocial stimuli compared to typically developing children. Using eye-tracking we show this difference is due to typically developing rather than autistic boys being more influenced by how interesting competing nonsocial objects are. On the other hand, reduced time looking at the eyes in autistic relative to typically developing boys is unaffected by nonsocial object salience. Time spent viewing social stimuli is associated with cognitive development and blood levels of oxytocin.

The oxytocin receptor gene polymorphism rs2268491 and serum oxytocin alterations are indicative of autism spectrum disorder: A case-control paediatric study in Iraq with personalized medicine implications

Background

Impairment of social functioning skills is a key hallmark of autism. The neuropeptide oxytocin (OXT) is a blood-based biomarker of social functioning, and a candidate for individualized treatment of ASD. The effects of OXT on the social brain are mediated by the OXT receptor (OXTR). This study assessed the clinical utility of blood OXT serum levels and the OXT receptor (OXTR) genotype as biomarkers of autism and its severity in a pediatric population in Iraq.

Methods

Blood samples were collected from patients with a clinical diagnosis of ASD (n = 60) and corresponding age and gender matched healthy controls (n = 60). All clinical samples were processed at the Department of Pathology and Forensic Medicine, Faculty of Medicine, University of Kufa in Iraq. Blood serum was assayed for OXT by sandwich ELISA. Receiver operator analysis (ROC) determined area under the curve (AUC), cutoff values, and sensitivity and specificity of OXT values for accuracy of diagnosis of ASD. Isolated genomic DNA was genotyped for the OXTR gene rs2268491(C/T) SNP using allele-specific PCR. The significance of genotype (CC, CT, and TT) and allele (C and T) distributions in different patient groups was assessed using odd ratios (OR) with 95% confidence intervals (CI) and the Chi-square test. All statistical analysis was performed used SPSS software.

Results

Study characteristics in the ASD population revealed a high level of consanguinity (36.66%), and ASD recurrence rate (11.66%) and family history (28.33%). OXT levels in patients with ASD (157.58±28.81 pg/ml) were significantly higher (p = 0.003) compared to controls (75.03±6.38 pg/ml). Within stratified ASD severity groups—OXT levels were significantly different (P = 0.032). ROC analysis determined similar AUC values for overall ASD (0.807), and stratified mild (0.793), moderate (0.889), and severe categories (0.795). The best cutoff for diagnosis of ASD was 83.8 pg/ml OXT with a sensitivity and specificity of 80% and 72.1% respectively. OXTR gene rs2268491(C/T) genotyping found that ASD patients have significantly lower (p = 0.021) genotype CC frequency and a significantly higher (p = 0.04) occurrence of the heterozygous CT genotype relative to controls. ASD subjects produced highest OXT levels with the TT genotype. T allele distribution was higher in ASD males. ASD males had significantly lower distribution of the CC genotype (48.89%) compared to females (80%) (Chi-square test: χ2 = 4.43, df = 1, p = 0.035). Whereas distribution of the CT genotype was significantly higher in autistic males (44.45%) compared to females (13.33%) (Chi-square test: χ2 = 4.68, df = 1, p = 0.03).

Conclusion

Peripheral OXT levels and OXTR genetic alterations are potential biomarkers of social functioning in the ASD patient setting. The stratification of patients with ASD into severity categories shows significant differences both in OXT levels and OXTR (rs2268491, C/T) genotype and allele distributions, that can be sex dependent. OXT based therapies will require personalized medicine tactics to correctly identify patients with ASD who require neuropeptide boosting in social settings.

Oxytocin and vasopressin in the hippocampus

Oxytocin (OXT) and vasopressin (AVP) are related neuropeptides that exert a wide range of effects on general health, homeostasis, development, reproduction, adaptability, cognition, social and nonsocial behaviors. The two peptides are mainly of hypothalamic origin and execute their peripheral and central physiological roles via OXT and AVP receptors, which are members of the G protein-coupled receptor family. These receptors, largely distributed in the body, are abundantly expressed in the hippocampus, a brain region particularly vulnerable to stress exposure and various lesions. OXT and AVP have important roles in the hippocampus, by modulating important processes like neuronal excitability, network oscillatory activity, synaptic plasticity, and social recognition memory. This chapter includes an overview regarding OXT and AVP structure, synthesis, receptor distribution, and functions, focusing on their relationship with the hippocampus and mechanisms by which they influence hippocampal activity. Brief information regarding hippocampal structure and susceptibility to lesions is also provided. The roles of OXT and AVP in neurodevelopment and adult central nervous system function and disorders are highlighted, discussing their potential use as targeted therapeutic tools in neuropsychiatric diseases.

Multiple Aspects of Inappropriate Action of Renin-Angiotensin, Vasopressin, and Oxytocin Systems in Neuropsychiatric and Neurodegenerative Diseases

The cardiovascular system and the central nervous system (CNS) closely cooperate in the regulation of primary vital functions. The autonomic nervous system and several compounds known as cardiovascular factors, especially those targeting the renin–angiotensin system (RAS), the vasopressin system (VPS), and the oxytocin system (OTS), are also efficient modulators of several other processes in the CNS. The components of the RAS, VPS, and OTS, regulating pain, emotions, learning, memory, and other cognitive processes, are present in the neurons, glial cells, and blood vessels of the CNS. Increasing evidence shows that the combined function of the RAS, VPS, and OTS is altered in neuropsychiatric/neurodegenerative diseases, and in particular in patients with depression, Alzheimer’s disease, Parkinson’s disease, autism, and schizophrenia. The altered function of the RAS may also contribute to CNS disorders in COVID-19. In this review, we present evidence that there are multiple causes for altered combined function of the RAS, VPS, and OTS in psychiatric and neurodegenerative disorders, such as genetic predispositions and the engagement of the RAS, VAS, and OTS in the processes underlying emotions, memory, and cognition. The neuroactive pharmaceuticals interfering with the synthesis or the action of angiotensins, vasopressin, and oxytocin can improve or worsen the effectiveness of treatment for neuropsychiatric/neurodegenerative diseases. Better knowledge of the multiple actions of the RAS, VPS, and OTS may facilitate programming the most efficient treatment for patients suffering from the comorbidity of neuropsychiatric/neurodegenerative and cardiovascular diseases.

Intraamygdaloid Oxytocin Reduces Anxiety in the Valproate-Induced Autism Rat Model

Background: Autism spectrum disorder (ASD) is a lifelong neurodevelopmental disorder affecting about 1.5% of children, and its prevalence is increasing. Anxiety is one of the most common comorbid signs of ASD. Despite the increasing prevalence, the pathophysiology of ASD is still poorly understood, and its proper treatment has not been defined yet. In order to develop new therapeutic approaches, the valproate- (VPA) induced rodent model of autism can be an appropriate tool. Oxytocin (OT), as a prosocial hormone, may ameliorate some symptoms of ASD. Methods: In the present study, we investigated the possible anxiolytic effect of intraamygdaloid OT on VPA-treated rats using the elevated plus maze test. Results: Our results show that male Wistar rats prenatally exposed to VPA spent significantly less time in the open arms of the elevated plus maze apparatus and performed significantly less head dips from the open arms. Bilateral OT microinjection into the central nucleus of the amygdala increased the time spent in the open arms and the number of head dips and reduced the anxiety to the healthy control level. An OT receptor antagonist blocked the anxiolytic effects of OT. The antagonist by itself did not influence the time rats spent in the open arms. Conclusions: Our results show that intraamygdaloid OT has anxiolytic effects in autistic rats.

The GABA Polarity Shift and Bumetanide Treatment: Making Sense Requires Unbiased and Undogmatic Analysis

GABA depolarizes and often excites immature neurons in all animal species and brain structures investigated due to a developmentally regulated reduction in intracellular chloride concentration ([Cl-]i) levels. The control of [Cl-]i levels is mediated by the chloride cotransporters NKCC1 and KCC2, the former usually importing chloride and the latter exporting it. The GABA polarity shift has been extensively validated in several experimental conditions using often the NKCC1 chloride importer antagonist bumetanide. In spite of an intrinsic heterogeneity, this shift is abolished in many experimental conditions associated with developmental disorders including autism, Rett syndrome, fragile X syndrome, or maternal immune activation. Using bumetanide, an EMA- and FDA-approved agent, many clinical trials have shown promising results with the expected side effects. Kaila et al. have repeatedly challenged these experimental and clinical observations. Here, we reply to the recent reviews by Kaila et al. stressing that the GABA polarity shift is solidly accepted by the scientific community as a major discovery to understand brain development and that bumetanide has shown promising effects in clinical trials.

Systematic review of prenatal exposure to endocrine disrupting chemicals and autism spectrum disorder in offspring

LAY ABSTRACT

Autism spectrum disorders comprise a complex group with many subtypes of behaviorally defined neurodevelopmental abnormalities in two core areas: deficits in social communication and fixated, restricted, repetitive, or stereotyped behaviors and interests each with potential unique risk factors and characteristics. The underlying mechanisms and the possible causes of autism spectrum disorder remain elusive and while increased prevalence is undoubtable, it is unclear if it is a reflection of diagnostic improvement or emerging risk factors such as endocrine disrupting chemicals. Epidemiological studies, which are used to study the relation between endocrine disrupting chemicals and autism spectrum disorder, can have inherent methodological challenges that limit the quality and strength of their findings. The objective of this work is to systematically review the treatment of these challenges and assess the quality and strength of the findings in the currently available literature. The overall quality and strength were "moderate" and "limited," respectively. Risk of bias due to the exclusion of potential confounding factors and the lack of accuracy of exposure assessment methods were the most prevalent. The omnipresence of endocrine disrupting chemicals and the biological plausibility of the association between prenatal exposure and later development of autism spectrum disorder highlight the need to carry out well-designed epidemiological studies that overcome the methodological challenges observed in the currently available literature in order to be able to inform public policy to prevent exposure to these potentially harmful chemicals and aid in the establishment of predictor variables to facilitate early diagnosis of autism spectrum disorder and improve long-term outcomes.

Role of Oxytocin in Different Neuropsychiatric, Neurodegenerative, and Neurodevelopmental Disorders

Oxytocin has recently gained significant attention because of its role in the pathophysiology and management of dominant neuropsychiatric disorders. Oxytocin, a peptide hormone synthesized in the hypothalamus, is released into different brain regions, acting as a neurotransmitter. Receptors for oxytocin are present in many areas of the brain, including the hypothalamus, amygdala, and nucleus accumbens, which have been involved in the pathophysiology of depression, anxiety, schizophrenia, autism, Alzheimer's disease, Parkinson's disease, and attention deficit hyperactivity disorder. Animal studies have spotlighted the role of oxytocin in social, behavioral, pair bonding, and mother-infant bonding. Furthermore, oxytocin protects fetal neurons against injury during childbirth and affects various behaviors, assuming its possible neuroprotective characteristics. In this review, we discuss some of the concepts and mechanisms related to the role of oxytocin in the pathophysiology and management of some neuropsychiatric, neurodegenerative, and neurodevelopmental disorders.

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.

Research Progress in Vitamin A and Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder. Over the past few decades, many studies have investigated the effects of VA supplementation in ASD patients and the relationship between vitamin A (VA) levels and ASD. VA is an essential micronutrient that plays an important role in various systems and biological processes in the form of retinoic acid (RA). Recent studies have shown that serum VA concentration is negatively correlated with the severity of ASD. The lack of VA during pregnancy or early fetal development can affect brain development and lead to long-term or even permanent impairment in the learning process, memory formation, and cognitive function. In addition, VA deficiency has been reported to have a major impact on the gastrointestinal function of children with ASD, while VA supplementation has been shown to improve the symptoms of ASD to a certain extent. This paper provides a comprehensive review of the relationship between VA and ASD.

Endogenous Oxytocin Levels in Autism-A Meta-Analysis

Oxytocin (OT) circuitry plays a major role in the mediation of prosocial behavior. Individuals with autism spectrum disorder (ASD) are characterized by impairments in social interaction and communication and have been suggested to display deficiencies in central OT mechanisms. The current preregistered meta-analysis evaluated potential group differences in endogenous OT levels between individuals with ASD and neurotypical (NT) controls. We included 18 studies comprising a total of 1422 participants. We found that endogenous OT levels are lower in children with ASD as compared to NT controls (n = 1123; g = -0.60; p = 0.006), but this effect seems to disappear in adolescent (n = 152; g = -0.20; p = 0.53) and adult populations (n = 147; g = 0.27; p = 0.45). Secondly, while no significant subgroup differences were found in regard to sex, the group difference in OT levels of individuals with versus without ASD seems to be only present in the studies with male participants (n = 814; g = -0.44; p = 0.08) and not female participants (n = 192; g = 0.11; p = 0.47). More research that employs more homogeneous methods is necessary to investigate potential developmental changes in endogenous OT levels, both in typical and atypical development, and to explore the possible use of OT level measurement as a diagnostic marker of ASD.

Oxytocin: A citation network analysis of 10 000 papers

Our understanding of the oxytocin system has been built over the last 70 years by the work of hundreds of scientists, reported in thousands of papers. Here, we construct a map to that literature, using citation network analysis in conjunction with bibliometrics. The map identifies ten major 'clusters' of papers on oxytocin that differ in their particular research focus and that densely cite papers from the same cluster. We identify highly cited papers within each cluster and in each decade, not because citations are a good indicator of quality, but as a guide to recognising what questions were of wide interest at particular times. The clusters differ in their temporal profiles and bibliometric features; here, we attempt to understand the origins of these differences.

Assessment of Reward-Related Brain Function After a Single Dose of Oxytocin in Autism: A Randomized Controlled Trial

Background

Autism spectrum disorder (ASD) is characterized by difficulties in social communication and interaction, which have been related to atypical neural processing of rewards, especially in the social domain. As intranasal oxytocin has been shown to modulate activation of the brain’s reward circuit, oxytocin might ameliorate the processing of social rewards in ASD and thus improve social difficulties.

Methods

In this randomized, double-blind, placebo-controlled, crossover functional magnetic resonance imaging study, we examined effects of a 24-IU dose of intranasal oxytocin on reward-related brain function in 37 men with ASD without intellectual impairment and 37 age- and IQ-matched control participants. Participants performed an incentive delay task that allows the investigation of neural activity associated with the anticipation and receipt of monetary and social rewards.

Results

Nonsignificant tests suggested that oxytocin did not influence neural processes related to the anticipation of social or monetary rewards in either group. Complementary Bayesian analyses indicated moderate evidence for a null model, relative to an alternative model. Our results were inconclusive regarding possible oxytocin effects on amygdala responsiveness to social rewards during reward consumption. There were no significant differences in reward-related brain function between the two groups under placebo.

Conclusions

Our results do not support the hypothesis that intranasal oxytocin generally enhances activation of reward-related neural circuits in men with and without ASD.

Serum Oxytocin Level Correlates With Gut Microbiome Dysbiosis in Children With Autism Spectrum Disorder

To investigate the levels of serum oxytocin (OT) in children with autism spectrum disorder (ASD) and explore the association between OT levels and gut microbiota relative abundances, we recruited 39 children with ASD children-mother dyads and 44 healthy controls. Serum OT levels were determined via enzyme-linked immunosorbent assay and gut microbiota abundances were determined by 16S rRNA sequencing. We found that the OT level of ASD was lower than the healthy control group overall (P < 0.05). Furthermore, we present preliminary evidence of gut microbiome dysbiosis observed among children with ASD to lower levels of OT based on correlational analysis between serum OT and specific gut microbiota abundances (P < 0.05). We also found sex-related differences in serum OT levels and GIS index (P < 0.05). However, the generalizability of findings relevant to females with ASD require further validation in future studies involving larger sample sizes and balanced sex distributions due to the small number of females involved in this study. Nonetheless, these new findings further our understanding of the effects of low serum OT levels among individuals with ASD, which provides preliminary evidence in hopes of guiding future study design or mechanistic studies. The findings of the present study may be suggestive of potential ASD subtypes based on ASD severity and gut microbiome composition that may facilitate the prediction of the therapeutic responses of OT among those with ASD.

Prenatal exposure to valproic acid and treatment with intranasal oxytocin have sex-specific effects on behavior in Long Evans rats

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social behaviors and communication. In rodents and humans, prenatal exposure to antiepileptic valproic acid is associated with an increased risk for autistic-like characteristics. One potential treatment is oxytocin, a prosocial neuropeptide that can be delivered intranasally. However, the sex-specific effects of valproic acid exposure and intranasal oxytocin treatment on behavior have not been fully explored. Pregnant Long Evans rats were administered valproic acid (500 mg/kg) or saline midday on gestational day 12, and after weaning, male and female pups were assigned to control (saline-saline), valproic acid-saline, or valproic acid-oxytocin groups. Oxytocin (0.8 IU/kg) or saline was delivered intranasally 30-60 min before tests for anxiety-like behaviors (elevated plus maze), social interactions (sociability) and sociosexual behaviors (partner preference, 50 kHz vocalizations and scent marking). Prenatal exposure to valproic acid resulted in sex-specific differences in behavior. When compared to controls, valproic acid males showed enhanced anxiety-like behaviors in adolescence and fewer scent marks in adulthood, while valproic acid females showed reduced sexual (partner) preference as adults. Intranasal oxytocin was anxiolytic for valproic acid males, but moderately anxiogenic for valproic acid females, and in both sexes it surprisingly impaired social interactions in the sociability test. Furthermore, intranasal oxytocin failed to improve sociosexual deficits in valproic acid rats. These findings highlight the importance of conducting preclinical studies in both sexes, and suggest that oxytocin may be an effective treatment in animal models with heightened anxiety-like behaviors.

Did Dog Domestication Contribute to Language Evolution?

Different factors seemingly account for the emergence of present-day languages in our species. Human self-domestication has been recently invoked as one important force favoring language complexity mostly via a cultural mechanism. Because our self-domestication ultimately resulted from selection for less aggressive behavior and increased prosocial behavior, any evolutionary or cultural change impacting on aggression levels is expected to have fostered this process. Here, we hypothesize about a parallel domestication of humans and dogs, and more specifically, about a positive effect of our interaction with dogs on human self-domestication, and ultimately, on aspects of language evolution, through the mechanisms involved in the control of aggression. We review evidence of diverse sort (ethological mostly, but also archeological, genetic, and physiological) supporting such an effect and propose some ways of testing our hypothesis.

Beta-Carotene derivatives as novel therapy for the prevention and treatment of autistic symptoms

Autistic Spectrum Disorders (ASD) are neurodevelopmental disorders characterized by impaired social interaction & communication as well as restricted and repetitive behavior. The currently reported incidence of ASD is 1-2%, and it increases dramatically to 10-20% in families predisposed to ASD. To date, there is no effective way to treat or prevent ASD, and only symptomatic treatment with limited efficacy is available. Oxytocin (Oxt) enhances affiliative behavior and improves social cognition. Social deficits characteristic of autism may be related to dysfunctional Oxt neurotransmission. Thus, administration of Oxt may relieve ASD, however it has a short plasma half-life and poor Blood Brain Barrier (BBB) permeability. CD38, a multifunctional ecto-enzyme expressed in brain and immune cells, was found to be critical for social behavior via regulation of Oxt secretion. All-trans retinoic acid (ATRA) is a potent inducer of CD38 and improves social behavior, but it is toxic and teratogenic. We have shown that beta-carotene has a similar therapeutic effect. The present study aimed to investigate the activity of novel beta-carotene derivatives in rescuing low sociability found in BTBR mice, providing an in vivo "proof of principle" that beta-carotene derivatives are potential agents to prevent/ameliorate the reappearance of ASD in high-risk populations for ASD. Beta-carotene and its synthetic analogs were administered orally to newborn BTBR mice with ASD associated like behavior. After 2 months, they were tested (at dosages of 0.1 and 1.0 mg/kg) by cognitive (T-maze spontaneous alteration and neurological score) and behavioral tests (reciprocal social interaction, repetitive grooming / bedding behavior), previously shown as indicators for autistic behavior. The following biochemical and molecular biology parameters were also examined: serum Oxt; gene expression in hippocampus and hypothalamus of CD 38, Oxt, Oxt receptor, BDNF, and retinoic acid receptor. The new compounds were significantly more effective than control. The most effective compounds, both in the behavioral tests and in their biochemical effects, were (3R,3'R)-astaxanthin bis(N-Cbz-l-alanine ester) (3B(and (3S,3'S)-astaxanthin bis(N,N-dimethylglycine ester (5). They did not exert any neurological symptoms. Thus, beta-carotene derivatives may have the potential to prevent and/or ameliorate autistic symptoms when administered orally after birth to newborns of families predisposed to autism.

Oxytocin levels tend to be lower in autistic children: A meta-analysis of 31 studies

LAY ABSTRACT

Oxytocin is a hormone that mediates interpersonal relationships through enhancing social recognition, social memory, and reducing stress. It is released centrally into the cerebrospinal fluid, as well as peripherally into the blood, where it can easily be measured. Some studies indicate that the oxytocin system with its social implications might be different in people with autism spectrum disorder. With summarizing evidence of 31 studies, this meta-analysis suggests that children with autism spectrum disorder have lower blood oxytocin levels compared to neurotypical individuals. This might not be the case for adults with autism spectrum disorder, where we could not find a difference. Our findings motivate further exploration of the oxytocin system in children with autism spectrum disorder. This could lead to therapeutic options in treating autism spectrum disorder in childhood.

Randomized clinical trial shows no substantial modulation of empathy-related neural activation by intranasal oxytocin in autism

Evidence suggests that intranasal application of oxytocin facilitates empathy and modulates its underlying neural processes, which are often impaired in individuals with autism spectrum disorders (ASD). Oxytocin has therefore been considered a promising candidate for the treatment of social difficulties in ASD. However, evidence linking oxytocin treatment to social behavior and brain function in ASD is limited and heterogeneous effects might depend on variations in the oxytocin-receptor gene (OXTR). We examined 25 male ASD patients without intellectual disability in a double-blind, cross-over, placebo-controlled fMRI-protocol, in which a single dose of oxytocin or placebo was applied intranasally. Patients performed three experiments in the MRI examining empathy for other's physical pain, basic emotions, and social pain. All participants were genotyped for the rs53576 single-nucleotide polymorphism of the OXTR. Oxytocin increased bilateral amygdala responsiveness during the physical pain task for both painful and neutral stimuli. Other than that, there were no effects of oxytocin treatment. OXTR genotype did not significantly interact with oxytocin treatment. Our results contribute to the growing body of empirical literature suggesting heterogenous effects of oxytocin administration in ASD. To draw clinically relevant conclusions regarding the usefulness of oxytocin treatment, however, empirical studies need to consider methods of delivery, dose, and moderating individual factors more carefully in larger samples.

Intrapartum transfer of oxytocin across the human placenta: An ex vivo perfusion experiment

INTRODUCTION

Investigation of the maternal to fetal transfer of oxytocin across the dually perfused term human placenta.

METHODS

Human placentae obtained from term singleton pregnancies were utilized in a dual recirculating model of ex vivo placental perfusion. Six placentae from women delivering by elective cesarean at term were perfused, one blank and five with the test substance synthetic oxytocin (0.8 ng/mL) (OX) added to the maternal perfusate for 180 min. Antipyrine was used as positive control to validate overlap of the maternal and fetal circuits. The concentration of OX was determined by radioimmunoassay.

RESULTS

A fall in maternal concentration of OX was seen throughout the experiment. At 90 min of perfusion a state of equilibrium was reached between maternal and fetal concentrations; however after 180 min the fetal concentration of OX was higher than that of the maternal. 31 % of the test substance was accounted for at the end of the experiment - suggesting OX protein binding and a high degree of oxytocinase activity.

DISCUSSION

The ex vivo perfusion experiments revealed low transfer of OX to the fetal circuit below physiologically relevant concentrations.

Oxytocin and vasopressin: Signalling, behavioural modulation and potential therapeutic effects

Oxytocin (OT) and vasopressin (AVP) are endogenous ligands for OT and AVP receptors in the brain and in the peripheral system. Several studies demonstrate that OT and AVP have opposite roles in modulating stress, anxiety and social behaviours. Interestingly, both peptides and their receptors exhibit high sequence homology which could account for the biased signalling interaction of the peptides with OT and AVP receptors. However, how and under which conditions this crosstalk occurs in vivo remains unclear. In this review we shed light on the complexity of the roles of OT and AVP, by focusing on their signalling and behavioural differences and exploring the crosstalk between the receptor systems. Moreover, we discuss the potential of OT and AVP receptors as therapeutic targets to treat human disorders, such as autism, schizophrenia and drug abuse.

Biological Timing and Neurodevelopmental Disorders: A Role for Circadian Dysfunction in Autism Spectrum Disorders

Autism spectrum disorders (ASDs) are a spectrum of neurodevelopmental disorders characterized by impaired social interaction and communication, as well as stereotyped and repetitive behaviors. ASDs affect nearly 2% of the United States child population and the worldwide prevalence has dramatically increased in recent years. The etiology is not clear but ASD is thought to be caused by a combination of intrinsic and extrinsic factors. Circadian rhythms are the ∼24 h rhythms driven by the endogenous biological clock, and they are found in a variety of physiological processes. Growing evidence from basic and clinical studies suggest that the dysfunction of the circadian timing system may be associated with ASD and its pathogenesis. Here we review the findings that link circadian dysfunctions to ASD in both experimental and clinical studies. We first introduce the organization of the circadian system and ASD. Next, we review physiological indicators of circadian rhythms that are found disrupted in ASD individuals, including sleep-wake cycles, melatonin, cortisol, and serotonin. Finally, we review evidence in epidemiology, human genetics, and biochemistry that indicates underlying associations between circadian regulation and the pathogenesis of ASD. In conclusion, we propose that understanding the functional importance of the circadian clock in normal and aberrant neurodevelopmental processes may provide a novel perspective to tackle ASD, and clinical treatments for ASD individuals should comprise an integrative approach considering the dynamics of daily rhythms in physical, mental, and social processes.

Central Neurocircuits Regulating Food Intake in Response to Gut Inputs-Preclinical Evidence

The regulation of energy balance requires the complex integration of homeostatic and hedonic pathways, but sensory inputs from the gastrointestinal (GI) tract are increasingly recognized as playing critical roles. The stomach and small intestine relay sensory information to the central nervous system (CNS) via the sensory afferent vagus nerve. This vast volume of complex sensory information is received by neurons of the nucleus of the tractus solitarius (NTS) and is integrated with responses to circulating factors as well as descending inputs from the brainstem, midbrain, and forebrain nuclei involved in autonomic regulation. The integrated signal is relayed to the adjacent dorsal motor nucleus of the vagus (DMV), which supplies the motor output response via the efferent vagus nerve to regulate and modulate gastric motility, tone, secretion, and emptying, as well as intestinal motility and transit; the precise coordination of these responses is essential for the control of meal size, meal termination, and nutrient absorption. The interconnectivity of the NTS implies that many other CNS areas are capable of modulating vagal efferent output, emphasized by the many CNS disorders associated with dysregulated GI functions including feeding. This review will summarize the role of major CNS centers to gut-related inputs in the regulation of gastric function with specific reference to the regulation of food intake.

Oxytocin and cortisol concentrations in adults with and without autism spectrum disorder in response to physical exercise

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, whose core symptoms consist of deficits in social interaction and communication as well as restricted and repetitive behavior. Brain oxytocin (OXT) has been associated with various prosocial behaviors, and might, therefore, be involved in the pathogenesis of disorders associated with socio-emotional dysfunctions such as ASD. However, significant associations between central and peripheral OXT levels may only be present in response to physiological or stressful stimuli but were not shown under baseline conditions. In this study, we, therefore, investigated salivary and plasma OXT in response to physical exercise in adults with ASD (n ​= ​33, mean age: 36.8 ​± ​10.7 years) without intellectual impairment (IQ ​> ​70) and neurotypical controls (n ​= ​31, mean age: 31.0 ​± ​11.7 years). To stimulate the OXT system, we used rapid cycling and measured cortisol (CORT) concentrations to monitor the physiological stress response. When controlling for age, neither salivary OXT (p ​= ​.469), plasma OXT (p ​= ​.297) nor CORT (p ​= ​.667) concentrations significantly differed between groups at baseline. In addition, neither OXT nor CORT concentrations significantly differed between groups after physical exercise. Social anxiety traits were negatively correlated with plasma, but not saliva OXT concentrations in neurotypicals at baseline, while empathetic traits were positively correlated with saliva, but not plasma concentrations in autistic patients at baseline. No significant correlations between salivary and plasma OXT concentrations were found at any time point. Future studies including adult participants should investigate the effect of age on CORT and OXT concentrations in response to stress.

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Basal levels of cortisol and oxytocin did not differ in adults with ASD from controls.

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After physical exercise plasma oxytocin increased in ASD with low cortisol-response.

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Cortisol and oxytocin levels post-task did not significantly differ between groups.

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Social phobic traits predicted lower plasma oxytocin concentrations in controls.

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Empathetic traits predicted higher salivary oxytocin levels in ASD.

Oxytocin Signaling Pathway: From Cell Biology to Clinical Implications

BACKGROUND

In addition to the well-known role played in lactation and parturition, Oxytocin (OT) and OT receptor (OTR) are involved in many other aspects such as the control of maternal and social behavior, the regulation of the growth of the neocortex, the maintenance of blood supply to the cortex, the stimulation of limbic olfactory area to mother-infant recognition bond, and the modulation of the autonomic nervous system via the vagal pathway. Moreover, OT and OTR show antiinflammatory, anti-oxidant, anti-pain, anti-diabetic, anti-dyslipidemic and anti-atherogenic effects.

OBJECTIVE

The aim of this narrative review is to summarize the main data coming from the literature dealing with the role of OT and OTR in physiology and pathologic conditions focusing on the most relevant aspects.

METHODS

Appropriate keywords and MeSH terms were identified and searched in Pubmed. Finally, references of original articles and reviews were examined.

RESULTS

We report the most significant and updated data on the role played by OT and OTR in physiology and different clinical contexts.

CONCLUSION

Emerging evidence indicates the involvement of OT system in several pathophysiological mechanisms influencing brain anatomy, cognition, language, sense of safety and trust and maternal behavior, with the possible use of exogenous administered OT in the treatment of specific neuropsychiatric conditions. Furthermore, it modulates pancreatic β-cell responsiveness and lipid metabolism leading to possible therapeutic use in diabetic and dyslipidemic patients and for limiting and even reversing atherosclerotic lesions.