Genomic and epigenetic evidence for oxytocin receptor deficiency in autism

Functional characterization of OXTR-associated enhancers

The oxytocin receptor (OXTR) has a vital role in regulating human behavior, controlling lactation, parturition, pair bonding, maternal behavior, anxiety, and sociability. However, its regulatory elements and how variation in these sequences lead to behavioral changes remain largely unknown. Here, we identified seven OXTR candidate cis-regulatory elements (cCREs) from mouse and human hypothalamus single-cell RNA/ATAC-seq data and characterized them in cells and mice. Luciferase assays in hypothalamus cell lines identified three of the seven to be functional enhancers. Mouse enhancer assays for the most robust enhancer, OXTR candidate enhancer 7 (OCE7), found it to be active in the mouse olfactory bulb at postnatal day 28 and day 56. In summary, using genomic data coupled with cell and mouse enhancer assays, we characterized the OXTR regulatory landscape and identified a novel olfactory bulb OXTR-associated enhancer.

Genome-wide DNA methylation profiles in the raphe nuclei of patients with autism spectrum disorder

AIM

Autism spectrum disorder (ASD) has a strong genetic basis, yet its genetic complexities remain elusive. Current research highlights environmental factors and epigenetic processes, such as DNA methylation, as crucial in ASD development. This exploratory study addresses a gap in understanding epigenetic regulation in the dorsal raphe (DR)-a region regulating multiple neurotransmitters and implicated in ASD-by examining DNA methylation profiles in postmortem ASD and control brains.

METHODS

We comprehensively analyzed genome-wide DNA methylation profiles in the DR brain region (seven controls and five ASD) using the Infinium HumanMethylation450 BeadChip (Illumina). Additionally, quantitative polymerase chain reaction was used to measure messenger RNA levels of differentially methylated genes in ASD (11 controls and six ASD).

RESULTS

We identified differentially methylated regions (DMRs) between ASD and controls. These DMRs were located among various genomic regions, including promoters, gene bodies, and intergenic regions. Notably, we found hypermethylation in genes related to olfaction (e.g. OR2C3), which is regulated by serotonin. Additionally, we observed that the hypomethylation of promoter-associated CpG islands in RABGGTB, a gene related to autophagy and synaptic function, corresponded with its increased expression.

CONCLUSIONS

Our findings reveal extensive DNA methylation changes in critical genomic regions, shedding light on potential mechanisms underlying ASD. The identification of RABGGTB as a novel candidate gene, not listed in the SFARI database, underscores its significance and warrants further research to explore its role in ASD diagnosis. This study enhances our understanding of the epigenetic landscape in ASD, emphasizing the interplay between genetic and environmental factors in its pathophysiology.

Oxytocin and autism: Insights from clinical trials and animal models

Autism spectrum disorder is a highly heritable and heterogeneous neurodevelopmental disorder, characterized by impaired social interactions and repetitive behaviors. Despite its complex etiology, increasing evidence has linked autism to the oxytocin system. The oxytocin peptide has long been known as the "social hormone," and has been shown to increase attention to social cues, elevate salience of socially relevant stimuli, and increase learning and reward in social situations. Reduced oxytocin levels and mutations in the oxytocin system have been reported in autism patients, while exogenously delivered oxytocin has been shown to alleviate social interaction deficits in both patients and animal models. Here, we summarize the results of recent clinical trials using oxytocin nasal spray to treat individuals with autism, as well as studies of autism animal models with oxytocin system deficits, and the rescue of their social behavior deficits by oxytocin. Finally, we discuss factors influencing clinical outcomes and reflect on future directions.

The impact of the early environment on oxytocin receptor epigenetics and potential therapeutic implications

Oxytocin research is rapidly evolving and increasingly reveals that epigenetic modifications to the oxytocin receptor gene (OXTR) are functional, plastic, and reliable components of oxytocinergic system function. This review outlines how OXTR epigenetics are shaped by the early life environment, impact social-developmental outcomes, and have strong potential to serve as therapeutic targets. We first establish the malleability of OXTR epigenetics in infancy in both animal models and humans through research demonstrating the impact of the early life environment on OXTR DNA methylation (OXTRm) and subsequent social behavior. Next, we detail how OXTRm serves as a predictive mechanism for neurodevelopmental outcomes in animal models of social behavior such as the prairie vole, and summarize the role of OXTRm in psychiatric disorders, emotional processing, and attachment behavior in humans. We discuss the potential of further OXTRm research to improve oxytocin therapeutics by highlighting how a deeper knowledge of OXTRm could improve the therapeutic potential of exogenous oxytocin, how OXTRm may impact additional cellular mechanisms with therapeutic potential including control of the perinatal GABA switch, and how early life therapies may target the tuning of endogenous OXTRm. Finally, we review limitations of previous oxytocin research and make recommendations for future research. IMPACT: Previous research into oxytocin therapeutics has been hampered by methodological difficulties that may be improved by assay of the oxytocin receptor gene (OXTR) and its methylation (OXTRm) Key sites of OXTRm modification link early life exposures to developmental and behavioral outcomes OXTRm appears to have a critical period of development in early life Epigenetic modification of the oxytocin receptor gene could serve as a powerful target for therapeutic interventions.

How does neurochemistry affect attachment styles in humans? The role of oxytocin and the endogenous opioid system in sociotropy and autonomy - A systematic review

Oxytocin was hypothesised to play a critical role in forming and maintaining secure attachments, shown to confer resilience against affective disorders. The endogenous opioid system has also emerged as a key player in attachment dynamics. In this pre-registered systematic review, we investigated whether individual differences in the functioning of these neurochemical systems are related to attachment styles, following PRISMA guidelines. As predicted, individuals with higher oxytocin function exhibited more secure attachment styles (p = .006, n = 12 studies) and less insecure attachment styles (p = .021, n = 16 studies). Contrary to our hypothesis, we found no association of endogenous opioid function with insecure (p = 0.549, n = 11 studies) or secure attachment styles (p = .065, n = 11 studies). The lack of association between endogenous mu-opioid function and attachment styles remains inconclusive due to inconsistencies in the neurochemical measurements and lack of eligible studies. Therefore, further investigations into the role of the endogenous opioid system in attachment styles are needed. Our findings corroborate the hypothesis that individual differences in oxytocin function relate to differences in attachment styles.

Intimate partner violence during pregnancy: To screen or not to screen?

Intimate partner violence (IPV) during pregnancy emerges as a compelling and urgent concern within the domain of public health, casting a long shadow over a substantial cohort of women. Its pernicious consequences extend beyond the individual, enveloping the well-being of both the mother and the fetus, giving rise to an elevated risk of preterm birth, low birth weight, fetal harm, and maternal psychological distress, including depression, anxiety, post-traumatic stress disorder, and, tragically, maternal mortality. Despite the prevalence of IPV being comparable to other conditions like gestational diabetes and preeclampsia, a universal screening protocol for IPV remains absent globally. We reviewed the clinical guidelines and practices concerning IPV screening, painstakingly scrutinizing their contextual nuances across diverse nations. Our study unveils multifaceted challenges of implementing universal screening. These hurdles encompass impediments to victim awareness and disclosure, limitations in healthcare providers' knowledge and training, and the formidable structural barriers entrenched within healthcare systems. Concurrently, we delve into the potential biomarkers intricately entwined with IPV. These promising markers encompass inflammatory indicators, epigenetic and genetic influences, and a diverse array of chemical compounds and proteins. Lastly, we discussed various criteria for universal screening including (1) valid and reliable screening tool; (2) target population as pregnant women; (3) scientific evidence of screening programme; and (4) integration of education, testing, clinical services, and programme management to minimise the challenges, which are paramount. With the advancement of digital technology and various biomarkers identification, screening and detecting IPV in clinical settings can be conducted systemically. A systems-level interventions with academia-community-indutrial partnerships can help connect pregnant women to desire support services to avoid adverse maternal and child health outcomes.

Diverse Applications of the Anti-Diabetic Drug Metformin in Treating Human Disease

Metformin is a commonly used drug for treating type 2 diabetes. Metformin is an inexpensive drug with low/no side effects and is well tolerated in human patients of different ages. Recent therapeutic strategies for human disease have considered the benefits of drug repurposing. This includes the use of the anti-diabetic drug metformin. Accordingly, the anti-inflammatory, anti-cancer, anti-viral, neuroprotective, and cardioprotective potentials of metformin have deemed it a suitable candidate for treating a plethora of human diseases. As results from preclinical studies using cellular and animal model systems appear promising, clinical trials with metformin in the context of non-diabetes-related illnesses have been started. Here, we aim to provide a comprehensive overview of the therapeutic potential of metformin in different animal models of human disease and its suggested relationship to epigenetics and ailments with epigenetic components.

Effects of human-animal interaction on salivary and urinary oxytocin in children and dogs

Oxytocin pathways are hypothesized to play important roles in human-animal interactions and may contribute to some benefits of these interspecific social relationships. We explored the effects of naturalistic interactions between children and dogs on oxytocin release in both species, as well as associations between methylation of the oxytocin receptor gene (OXTRm), social behavior, and oxytocin response in this context. Children (N = 55) participated in a within-subjects design involving a) interaction with their pet dog, b) interaction with an unfamiliar dog, and c) a nonsocial control condition (solitary play). We used immunoassays to measure salivary and urinary oxytocin in both the children and dogs, behavioral coding to characterize dog-child interactions, and bisulfite sequencing to quantify methylation of the oxytocin receptor gene (N = 32 children). Child salivary oxytocin decreased moderately across time in all conditions, but the extent of this effect varied between conditions, with greater oxytocin output during interactions with dogs than the control condition. In the pet dog condition, children's salivary oxytocin response was positively associated with the duration of visual co-orientation between the child and dog. Child urinary oxytocin did not deviate substantially from baseline in any condition. Children with higher levels of OXTRm had greater oxytocin output during interactions with their pet dogs, but lower oxytocin output in the control condition, and engaged in lower levels of affectionate interaction with dogs across conditions. Children's pet dogs exhibited increases in salivary oxytocin, but we observed the opposite pattern in the unfamiliar dog, who exhibited decreases in both urinary and salivary oxytocin on average. Collectively, our results support the hypothesis that oxytocin pathways may shape and respond to social interactions between children and dogs, highlighting an important role for companion animals in child development.

Epigenetic regulation of the oxytocin system as an indicator of adaptation to over-controlling parenting and psychosocial functioning in adulthood

The oxytocin system plays a role in social stress adaptation, and this role is likely to be particularly important in adolescence. One method of regulating the oxytocin system is through DNA methylation in the promoter of the oxytocin receptor gene (OXTRm), which reduces the gene's expression. This multi-method, longitudinal study, using a diverse community sample of 184 adolescents followed from age 13-28, examined the links between OXTRm and exposure to over-controlling parenting in adolescence and conflict with romantic partners and internalizing symptoms in adulthood. Female, but not male, adolescents who were exposed to psychologically controlling parenting at age 13 had lower levels of OXTRm at site -924 at age 28. Reduced OXTRm at site -924 was associated with greater romantic partner-reported relationship conflict at age 27, and reduced OXTRm at site -934 was marginally associated with greater participant-reported conflict for males. Reduced OXTRm at site -924 was also associated with fewer internalizing symptoms at ages 24-25. These results in adulthood are consistent with an upregulated oxytocin system reducing the salience of negative socioemotional stimuli. Overall, findings are consistent with oxytocin playing a role in the stress response system, and more specifically, by helping us to adapt to social environments like parenting and romantic relationships, reducing the salience of negativity, and reducing risk for common emotional problems.

Facing infant cuteness: How nurturing care motivation and oxytocin system gene methylation are associated with responses to baby schema features

Baby schema features are a specific set of physical features-including chubby cheeks, large, low-set eyes, and a large, round head-that have evolutionary adaptive value in their ability to trigger nurturant care. In this study among nulliparous women (N = 81; M age = 23.60, SD = 0.44), we examined how sensitivity to these baby schema features differs based on individual variations in nurturant care motivation and oxytocin system gene methylation. We integrated subjective ratings with measures of facial expressions and electroencephalography (EEG) in response to infant faces that were manipulated to contain more or less pronounced baby schema features. Linear mixed effects analyses demonstrated that infants with more pronounced baby schema features were rated as cuter and participants indicated greater motivation to take care of them. Furthermore, infants with more pronounced baby schema features elicited stronger smiling responses and enhanced P2 and LPP amplitudes compared to infants with less pronounced baby schema features. Importantly, individual differences significantly predicted baby schema effects. Specifically, women with low OXTR methylation and high nurturance motivation showed enhanced differentiation in automatic neurophysiological responses to infants with high and low levels of baby schema features. These findings highlight the importance of considering individual differences in continued research to further understand the complexities of sensitivity to child cues, including facial features, which will improve our understanding of the intricate neurobiological system that forms the basis of caregiving behavior.

Exploring the role of OXTR gene methylation in attachment development: A longitudinal study

The current study explored longitudinally whether oxytocin receptor gene methylation (OXTRm) changes moderated the association between parental sensitivity changes and children's attachment changes over three waves. Six hundred six Flemish children (10-12 years, 42.8%-44.8% boys) completed attachment measures and provided salivary OXTRm data on seven CpG sites. Their parents reported their sensitive parenting. Results suggest that OXTRm changes hardly link to attachment (in)security changes after the age of 10. Some support was found for interaction effects between parental sensitivity changes and OXTRm changes on attachment changes over time. Effects suggest that for children with increased OXTRm in the promotor region and decreased methylation in the inhibitor region over time, increased parental sensitivity was associated with increased secure attachment and decreased insecure attachment over time.

Exploring key genes and pathways associated with sex differences in autism spectrum disorder: integrated bioinformatic analysis

Autism spectrum disorder (ASD) is a heterogenous neurodevelopmental disorder marked by functional abnormalities in brain that causes social and linguistic difficulties. The incidence of ASD is more prevalent in males compared to females, but the underlying mechanism, as well as molecular indications for identifying sex-specific differences in ASD symptoms remain unknown. Thus, impacting the development of personalized strategy towards pharmacotherapy of ASD. The current study employs an integrated bioinformatic approach to investigate the genes and pathways uniquely associated with sex specific differences in autistic individuals. Based on microarray dataset (GSE6575) extracted from the gene expression omnibus, the dysregulated genes between the autistic and the neurotypical individuals for both sexes were identified. Gene set enrichment analysis was performed to ascertain biological activities linked to the dysregulated genes. Protein-protein interaction network analysis was carried out to identify hub genes. The identified hub genes were examined to determine their functions and involvement in the associated pathways using Enrichr. Additionally, hub genes were validated from autism-associated databases and the potential small molecules targeting the hub genes were identified. The present study utilized whole blood transcriptomic gene expression analysis data and identified 2211 and 958 differentially expressed unique genes in males and females respectively. The functional enrichment analysis revealed that male hub genes were functionally associated with RNA polymerase II mediated transcriptional regulation whereas female hub genes were involved in intracellular signal transduction and cell migration. The top male hub genes exhibited functional enrichment in tyrosine kinase signalling pathway. The pathway enrichment analysis of male hub genes indicates the enrichment of papillomavirus infection. Female hub genes were enriched in androgen receptor signalling pathway and functionally enriched in focal adhesion specific excision repair. Identified drug like candidates targeting these genes may serve as a potential sex specific therapeutics. Wortmannin for males, 5-Fluorouracil for females had the highest scores. Targeted and sex-specific pharmacotherapies may be created for the management of ASD. The current investigation identifies sex-specific molecular signatures derived from whole blood which may serve as a potential peripheral sex-specific biomarkers for ASD. The study also uncovers the possible pharmacological interventions against the selected genes/pathway, providing support in development of therapeutic strategies to mitigate ASD. However, experimental proofs on biological systems are warranted.

[Oxytocin as a neuroprotective strategy in neonates: concept and preclinical evidence]

OBJECTIVE

Prematurity and intra-uterine growth retardation are responsible for brain damage associated with various neurocognitive and behavioral disorders in more than 9 million children each year. Most pharmacological strategies aimed at preventing perinatal brain injury have not demonstrated substantial clinical benefits so far. In contrast, enrichment of the newborn's environment appears to have positive effects on brain structure and function, influences newborn hormonal responses, and has lasting neurobehavioral consequences during infancy and adulthood. Oxytocin (OT), a neuropeptide released by the hypothalamus, may represent the hormonal basis for these long-term effects.

METHOD

This review of the literature summarizes the knowledge concerning the effect of OT in the newborn and the preclinical data supporting its neuroprotective effect.

RESULTS

OT plays a role during the perinatal period, in parent-child attachment and in social behavior. Furthermore, preclinical studies strongly suggest that endogenous and synthetic OT is capable of regulating the inflammatory response of the central nervous system in response to situations of prematurity or more generally insults to the developing brain. The long-term effect of synthetic OT administration during labor is also discussed.

CONCLUSION

All the conceptual and experimental data converge to indicate that OT would be a promising candidate for neonatal neuroprotection, in particular through the regulation of neuroinflammation.

The impact of childhood trauma exposure on social functioning in schizophrenia: the moderated mediation role of oxytocin and oxytocin receptor gene polymorphisms

BACKGROUND

Childhood trauma has been linked to increased risk of schizophrenia and social dysfunction, and oxytocin and its receptor gene have been implicated in regulating social behavior. This study investigated the potential role of oxytocin and oxytocin receptor gene (OXTR) in mediating the effects of childhood trauma on social functioning in schizophrenia.

METHODS

The study consisted of 382 patients with schizophrenia and 178 healthy controls who were assessed using the Taiwanese version of the Childhood Trauma Questionnaire (CTQ-SF), the Social Functioning Scale (SFS), and plasma oxytocin levels. DNA was extracted to genotype the OXTR and ten single-nucleotide polymorphisms (SNPs; rs2254298, rs237885, rs237887, rs237899, rs53576, rs9840864, rs13316193, rs7632287, rs1042778, and rs237895) were selected.

RESULTS

Patients with schizophrenia showed higher CTQ-SF scores (t = 12.549, p < 0.001), lower SFS scores (t = -46.951, p < 0.001), and lower plasma oxytocin levels (t = -5.448, p < 0.001) compared to healthy controls. The study also found significant differences in OXTR SNPs between both groups, with risk alleles being more prevalent in patients with schizophrenia (t = 2.734, p = 0.006). Results indicated a significant moderated mediation effect, with oxytocin and the OXTR SNPs partially mediating the relationship between childhood trauma exposure and social functioning in patients with schizophrenia (index of mediation = 0.038, 95% CI [0.033-0.044]).

CONCLUSIONS

The findings suggest that oxytocin and its receptor gene may be promising targets for interventions aimed at improving social functioning in patients with a history of childhood trauma and schizophrenia. However, further research is needed to fully understand these effects and the potential of oxytocin-based interventions in this population.

Feasibility Study to Compare Oxytocin Function Between Body Mass Index Groups at Term Labor Induction

OBJECTIVE

To determine the feasibility of a protocol to examine the association between oxytocin system function and birth outcomes in women with and without obesity before induction of labor.

DESIGN

Prospective descriptive.

SETTING

Academic medical center in the U.S. Midwest.

PARTICIPANTS

Pregnant women scheduled for induction of labor at 40 weeks of gestation or greater (n = 15 normal weight; n = 15 obese).

METHODS

We collected blood samples and abstracted data by chart review. We used percentages to examine adherence to protocol. We used t tests and chi-square tests to describe differences in sample characteristics, oxytocin system function variables, and birth outcomes between the body mass index groups.

RESULTS

The recruitment rate was 85.7%, protocol adherence was 97.1%, and questionnaire completion was 80.0%. Mean plasma oxytocin concentration was higher in the obese group (M = 2774.4 pg/ml, SD = 797.4) than in the normal weight group (M = 2193.5 pg/ml, SD = 469.8). Oxytocin receptor DNA percentage methylation (CpG -934) was higher in the obese group than in the normal weight group.

CONCLUSION

Our protocol was feasible and can serve as a foundation for estimating sample sizes in forthcoming studies investigating the diversity in oxytocin system measurements and childbirth outcomes among pregnant women in different body mass index categories.

Chronic oxytocin administration stimulates the oxytocinergic system in children with autism

Clinical efficacy of intranasal administration of oxytocin is increasingly explored in autism spectrum disorder, but to date, the biological effects of chronic administration regimes on endogenous oxytocinergic function are largely unknown. Here exploratory biological assessments from a completed randomized, placebo-controlled trial showed that children with autism (n = 79, 16 females) receiving intranasal oxytocin for four weeks (12 IU, twice daily) displayed significantly higher salivary oxytocin levels 24 hours after the last oxytocin nasal spray administration, but no longer at a four-week follow up session. Regarding salivary oxytocin receptor gene (OXTR) epigenetics (DNA-methylation), oxytocin-induced reductions in OXTR DNA-methylation were observed, suggesting a facilitation of oxytocin receptor expression in the oxytocin compared to the placebo group. Notably, heightened oxytocin levels post-treatment were significantly associated with reduced OXTR DNA-methylation and improved feelings of secure attachment. These findings indicate that four weeks of chronic oxytocin administration stimulated the endogenous oxytocinergic system in children with autism.

The Multifaceted Role of Oxytocinergic System and OXTR Gene

The article explores the multifaceted role of the neuropeptide oxytocin in human behavior and its connection to the oxytocin receptor ( OXTR ) gene. Oxytocin, produced in specific brain nuclei, is implicated in emotional, social, and maternal behaviors, stress reduction, uterine contraction during childbirth, and lactation. The OXTR gene, located on chromosome 3, encodes oxytocin receptors found in various body parts, including critical brain regions associated with social behaviors. The article delves into studies on rodents, revealing correlations between OXTR gene expression and pair bonding in the prefrontal cortex and social behavior regulation in the amygdala. The discussion extends to the impact of oxytocin on social support-seeking behavior, focusing on a specific genetic variation, rs53576. The article explores how this genetic variation influences empathy, stress reactivity, and susceptibility to disorders such as autism and social anxiety. Furthermore, the article examines structural and functional changes in the brain associated with OXTR gene variations. It discusses the role of DNA methylation in influencing oxytocin receptor availability, affecting social perception and responsiveness to negative stimuli. The article also highlights the oxytocinergic system's involvement in disorders such as autism and social anxiety, emphasizing the interplay between genetics and environmental factors. The article also touches on the potential therapeutic use of exogenous oxytocin in mitigating symptoms associated with these disorders. In summary, the article underscores the intricate relationship between oxytocin, the OXTR gene, and diverse aspects of human behavior, providing insights into social bonding, perception, and the development of behavioral disorders.

UBE3A: The Role in Autism Spectrum Disorders (ASDs) and a Potential Candidate for Biomarker Studies and Designing Therapeutic Strategies

Published reports from the CDC's Autism and Development Disabilities Monitoring Networks have shown that an average of 1 in every 44 (2.3%) 8-year-old children were estimated to have ASD in 2018. Many of the ASDs exhibiting varying degrees of autism-like phenotypes have chromosomal anomalies in the Chr15q11-q13 region. Numerous potential candidate genes linked with ASD reside in this chromosomal segment. However, several clinical, in vivo, and in vitro studies selected one gene more frequently than others randomly and unbiasedly. This gene codes for UBE3A or Ubiquitin protein ligase E3A [also known as E6AP ubiquitin-protein ligase (E6AP)], an enzyme involved in the cellular degradation of proteins. This gene has been listed as one of the several genes with a high potential of causing ASD in the Autism Database. The gain of function mutations, triplication, or duplication in the UBE3A gene is also associated with ASDs like Angelman Syndrome (AS) and Dup15q Syndrome. The genetic imprinting of UBE3A in the brain and a preference for neuronal maternal-specific expression are the key features of various ASDs. Since the UBE3A gene is involved in two main important diseases associated with autism-like symptoms, there has been widespread research going on in understanding the link between this gene and autism. Additionally, since no universal methodology or mechanism exists for identifying UBE3A-mediated ASD, it continues to be challenging for neurobiologists, neuroscientists, and clinicians to design therapies or diagnostic tools. In this review, we focus on the structure and functional aspects of the UBE3A protein, discuss the primary relevance of the 15q11-q13 region in the cause of ASDs, and highlight the link between UBE3A and ASD. We try to broaden the knowledge of our readers by elaborating on the possible mechanisms underlying UBE3A-mediated ASDs, emphasizing the usage of UBE3A as a prospective biomarker in the preclinical diagnosis of ASDs and discuss the positive outcomes, advanced developments, and the hurdles in the field of therapeutic strategies against UBE3A-mediated ASDs. This review is novel as it lays a very detailed and comprehensive platform for one of the most important genes associated with diseases showing autistic-like symptoms. Additionally, this review also attempts to lay optimistic feedback on the possible steps for the diagnosis, prevention, and therapy of these UBE3A-mediated ASDs in the upcoming years.

A targeted long-read sequencing approach questions the association of OXTR methylation with high-functioning autism

BACKGROUND

DNA sequence variation and altered epigenetic regulation of the oxytocin receptor gene (OXTR) have been implicated in autism and autistic-like behaviors. While previous studies have examined subsegments of OXTR, nanopore Cas9-targeted sequencing (nCATS) allows deep characterization of entire genes with simultaneous assessment of epigenetic 5-methylcytosine (5mC) modification and without the need for prior DNA amplification or bisulfite conversion. This pilot study uses an nCATS approach to sequence the entire OXTR gene and its regulatory construct and screen for 5mC modification to compare results between individuals with high-functioning autism (HFA) and neurotypical controls (NC).

METHODS

Using DNA extracted from peripheral blood, OXTR (Hg38, chr3: 8750381-8770434, 20,054 base pairs) was analyzed by nCATS. 5mC modification probabilities were calculated and visualized across the gene and differential methylation analysis was performed.

RESULTS

Twenty adults with HFA (10 males, 10 females) and 20 age- and sex-matched NC (± 5 years) were included. There were no apparent group differences in the entire OXTR gene sequence, except for the intron variant rs918316, which was clustered in the HFA group. However, differential methylation analysis did not reveal a single significant group-dependent differentially methylated site among the 412 CpG sites captured.

LIMITATIONS

Limitations of this study include the small number of samples due to the pilot nature of the study, which particularly limits the relevance of the sequence variants found. It should also be noted that the use of peripheral blood material limits the ability to draw conclusions about central processes.

CONCLUSIONS

Previous findings of autism-associated OXTR epigenetic alterations were not reproducible with our method. In our opinion, this may lead to a reconsideration of the relevance of altered methylation at individual OXTR CpG positions in autism research. However, given the pilot nature of the study, these results need to be replicated in independent cohorts and with larger sample sizes.

Mild internet use is associated with epigenetic alterations of key neurotransmission genes in salivary DNA of young university students

The potentially problematic use of the Internet is a growing concern worldwide, which causes and consequences are not completely understood yet. The neurobiology of Internet addiction (IA) has attracted much attention in scientific research, which is now focusing on identifying measurable biological markers. Aim of this study was to investigate epigenetic and genetic regulation of oxytocin receptor (OXTR), dopamine transporter (DAT1) and serotonin transporter (SERT) genes using DNA obtained from saliva samples of young university students: the Internet Addiction Test (IAT) was administered to evaluate the potential existence and intensity of IA. Significant changes in DNA methylation levels at OXTR, DAT1 and SERT genes were observed in the 30 < IAT < 49 group (mild-risk internet users) compared to the IAT < 29 subjects (complete control of internet use) and IAT > 50 subjects (considered as moderately addicted). Moreover, epigenetic markers were significantly correlated, either directly (for OXTR and DAT1) or inversely (OXTR and DAT1 versus SERT), to the psychometric properties. Our data confirmed the association of OXTR, DAT1 and SERT genes in processes related to behavioural addictions and might be of relevance to suggest possible biological predictors of altered behaviours and the eventual vulnerability to develop an IA. Different other genetic pathways have been suggested to play a role in IA and research is ongoing to better define them, in order to help in the early diagnosis as well as in the development of new potential treatments.

Comprehensive evaluation of the implementation of episignatures for diagnosis of neurodevelopmental disorders (NDDs)

Episignatures are popular tools for the diagnosis of rare neurodevelopmental disorders. They are commonly based on a set of differentially methylated CpGs used in combination with a support vector machine model. DNA methylation (DNAm) data often include missing values due to changes in data generation technology and batch effects. While many normalization methods exist for DNAm data, their impact on episignature performance have never been assessed. In addition, technologies to quantify DNAm evolve quickly and this may lead to poor transposition of existing episignatures generated on deprecated array versions to new ones. Indeed, probe removal between array versions, technologies or during preprocessing leads to missing values. Thus, the effect of missing data on episignature performance must also be carefully evaluated and addressed through imputation or an innovative approach to episignatures design. In this paper, we used data from patients suffering from Kabuki and Sotos syndrome to evaluate the influence of normalization methods, classification models and missing data on the prediction performances of two existing episignatures. We compare how six popular normalization methods for methylarray data affect episignature classification performances in Kabuki and Sotos syndromes and provide best practice suggestions when building new episignatures. In this setting, we show that Illumina, Noob or Funnorm normalization methods achieved higher classification performances on the testing sets compared to Quantile, Raw and Swan normalization methods. We further show that penalized logistic regression and support vector machines perform best in the classification of Kabuki and Sotos syndrome patients. Then, we describe a new paradigm to build episignatures based on the detection of differentially methylated regions (DMRs) and evaluate their performance compared to classical differentially methylated cytosines (DMCs)-based episignatures in the presence of missing data. We show that the performance of classical DMC-based episignatures suffers from the presence of missing data more than the DMR-based approach. We present a comprehensive evaluation of how the normalization of DNA methylation data affects episignature performance, using three popular classification models. We further evaluate how missing data affect those models' predictions. Finally, we propose a novel methodology to develop episignatures based on differentially methylated regions identification and show how this method slightly outperforms classical episignatures in the presence of missing data.

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.

Hippocampal and peripheral blood DNA methylation signatures correlate at the gene and pathway level in a mouse model of autism

Autism spectrum disorders (ASD) are polygenic multifactorial disorders influenced by environmental factors. ASD-related differential DNA methylation has been found in human peripheral tissues, such as placenta, paternal sperm, buccal epithelium, and blood. However, these data lack direct comparison of DNA methylation levels with brain tissue from the same individual to determine the extent that peripheral tissues are surrogates for behavior-related disorders. Here, whole genome methylation profiling at all the possible sites throughout the mouse genome (>25 million) from both brain and blood tissues revealed novel insights into the systemic contributions of DNA methylation to ASD. Sixty-six differentially methylated regions (DMRs) share the same genomic coordinates in these two tissues, many of which are linked to risk genes for neurodevelopmental disorders and intellectual disabilities (e.g. Prkch, Ptn, Hcfc1, Mid1, and Nfia). Gene ontological pathways revealed a significant number of common terms between brain and blood (N = 65 terms), and nearly half (30/65) were associated with brain/neuronal development. Furthermore, seven DMR-associated genes among these terms contain methyl-sensitive transcription factor sequence motifs within the DMRs of both tissues; four of them (Cux2, Kcnip2, Fgf13, and Mrtfa) contain the same methyl-sensitive transcription factor binding sequence motifs (HES1/2/5, TBX2 and TFAP2C), suggesting DNA methylation influences the binding of common transcription factors required for gene expression. Together, these findings suggest that peripheral blood is a good surrogate tissue for brain and support that DNA methylation contributes to altered gene regulation in the pathogenesis of ASD.

DNA methylation of the oxytocin receptor interacts with age to impact neural response to social stimuli

Introduction

Social isolation is one of the strongest predictors of increased risk of mortality in older adulthood. The ability to form and maintain the social relationships that mitigate this risk is partially regulated by the oxytocinergic system and one's ability to attend to and process social information. We have previously shown that an epigenetic change to the DNA of the oxytocin receptor gene (OXTR methylation) affects the salience of social information in young adults. Little is known about how the oxytocinergic system ages and what effect this aging system has on social cognitive abilities throughout the lifespan.

Methods

Here we explored age-related differences in the association between neural response during selective social attention and OXTR DNA methylation in young (age 18-31) and older (age 58-81) adults. Participants underwent fMRI during a selective social attention task and provided a DNA sample for the assessment of OXTR methylation.

Results and Discussion

We found that older adults activated diffuse areas of visual cortex and dorsolateral prefrontal cortex during selective social attention, consistent with the dedifferentiation and compensatory neural activation commonly reported in aging. We found a significant age-by-OXTR methylation interaction on neural response when attending to social stimuli in a complex display; young adults displayed a positive association between OXTR methylation and neural activation, replicating our prior finding that young adults with presumed diminished endogenous access to oxytocin recruit regions of the attentional cortex to a greater extent. This association did not hold for older adults. Instead, perceived social support interacted with OXTR methylation to influence neural response during selective social attention. These data suggest that environmental factors like social support moderate biological processes in aging and highlight the importance of a lifespan perspective for understanding associations between individual differences in the oxytocinergic system, neural function, and social behavior.

Maternal outcomes related to Genetic and epigenetic Variation in the oxytocin system: A scoping review

Purpose

In this scoping review, we synthesize the literature on oxytocin and oxytocin receptor genetic and epigenetic variation in relationship to breastfeeding, maternal caregiving behavior, and maternal mental health.

Methods

A literature search was conducted in early 2022, and updated in 2023, utilizing the PRISMA scoping review reporting method, using the following MeSH headings and key terms: oxytocin, oxytocin receptor, genetics, epigenetics, methylation, pregnancy, postnatal, breastfeeding, lactation, mother-infant relations and perinatal outcomes. The search was conducted using PubMed, EMBASE, CINAHL, Google Scholar, SCOPUS, and the Cochrane Library. Inclusion criteria included: human literature which was peer reviewed and found in primary sources, printed in the English language. In addition, the study must have reported genetic/epigenetic data in either the oxytocin or oxytocin receptor gene (maternal or infant up to 12 months after birth) in relation to a breastfeeding, maternal caregiving behavior or a maternal mental health outcome. There was no date limitation. Four authors reviewed studies for eligibility. Data was extracted using a structured data extraction form.

Results

A total of 23 studies met inclusion criteria for this review (breastfeeding n = 4, maternal caregiving behavior n = 7, and maternal mental health n = 16). Seventeen papers reported on oxytocin or oxytocin receptor genotype and nine reported epigenetic associations (namely DNA methylation). These totals are greater than 23, as studies reported on multiple outcomes. One paper assessed the interaction between genotype and methylation. While a number of genotype variations were reported, the single nucleotide polymorphism rs53576 on the oxytocin receptor gene was the most studied. Overall, variation in this polymorphism was related to postnatal depression symptoms. Among numerous epigenetic markers, site -934 was the most studied methylation site, and methylation status was associated with maternal depression and maternal caregiving behavior outcomes. Results suggest that early life experiences impact adult maternal caregiving behaviors and mental health outcomes, and vary based on genetic vulnerability. Breastfeeding outcomes were minimally studied.

Conclusion

This scoping review found that genetic and epigenetic variation at the oxytocin and oxytocin receptor genes were associated with maternal caregiving behavior and mental health, likely through complex gene and environment interactions. The findings suggest that maternal early life experiences and stress impact later caregiving behaviors and mental health in the postnatal period. The findings highlight potential pathways by which environment, experiences, and genes interact to impact maternal caregiving behavior and maternal mental health.

Oxytocin Receptor Expression in Hair Follicle Stem Cells: A Promising Model for Biological and Therapeutic Discovery in Neuropsychiatric Disorders

The intricate nature of the human brain and the limitations of existing model systems to study molecular and cellular causes of neuropsychiatric disorders represent a major challenge for basic research. The promising progress in patient-derived stem cell technology and in our knowledge on the role of the brain oxytocin (OXT) system in health and disease offer new possibilities in that direction. In this study, the rat hair follicle stem cells (HFSCs) were isolated and expanded in vitro. The expression of oxytocin receptors (OXTR) was evaluated in these cells. The cellular viability was assessed 12 h post stimulation with OXT. The activation of OXTR-coupled intracellular signaling cascades, following OXT treatment was determined. Also, the influence of OXT on neurite outgrowth and cytoskeletal rearrangement were defined. The assessment of OXTR protein expression revealed this receptor is expressed abundantly in HFSCs. As evidenced by the cell viability assay, no adverse or cytotoxic effects were detected following 12 h treatment with different concentrations of OXT. Moreover, OXTR stimulation by OXT resulted in ERK1/2, CREB, and eEF2 activation, neurite length alterations, and cytoskeletal rearrangements that reveal the functionality of this receptor in HFSCs. Here, we introduced the rat HFSCs as an easy-to-obtain stem cell model that express functional OXTR. This cell-based model can contribute to our understanding of the progression and treatment of neuropsychiatric disorders with oxytocinergic system deficiency.

Epigenetic modification of the oxytocin receptor gene is associated with child-parent neural synchrony during competition

Interpersonal neural synchrony (INS) occurs when neural electrical activity temporally aligns between individuals during social interactions. It has been used as a metric for interpersonal closeness, often during naturalistic child-parent interactions. This study evaluated whether other biological correlates of social processing predicted the prevalence of INS during child-parent interactions, and whether their observed cooperativity modulated this association. Child-parent dyads (n = 27) performed a visuospatial tower-building task in cooperative and competitive conditions. Neural activity was recorded using mobile electroencephalogram (EEG) headsets, and experimenters coded video-recordings post-hoc for behavioral attunement. DNA methylation of the oxytocin receptor gene (OXTRm) was measured, an epigenetic modification associated with reduced oxytocin activity and socioemotional functioning. Greater INS during competition was associated with lower child OXTRm, while greater behavioral attunement during competition and cooperation was associated with higher parent OXTRm. These differential relationships suggest that interpersonal dynamics as measured by INS may be similarly reflected by other biological markers of social functioning, irrespective of observed behavior. Children's self-perceived communication skill also showed opposite associations with parent and child OXTRm, suggesting complex relationships between children's and their parents' social functioning. Our findings have implications for ongoing developmental research, supporting the utility of biological metrics in characterizing interpersonal relationships.

Chronic Ambient Ozone Exposure Aggravates Autism-Like Symptoms in a Susceptible Mouse Model

Although there is evidence that exposure to ground-level ozone (O3) may cause an increased risk of neurological disorders (e.g., autistic spectrum disorder), low-dose chronic ozone exposure and its adverse effects on the nervous system have not been fully understood. Here, we evaluated the potential neurotoxic effects of long-term exposure to environmentally relevant O3 concentration (200 μg/m3 via a whole-body inhalation system, 12 h/day for 5 days/week) using a susceptible mouse model of autism induced by valproic acid. Various indicators of oxidative stress, mitochondria, and synapse in the brain tissues were then measured to determine the overall damage of O3 to the mouse brain. The results showed an aggravated risk of autism in mice offspring, which was embodied in decreased antioxidant contents, disturbed energy generation in mitochondria, as well as reduced expressions of protein kinase Mζ (PKMζ) and synaptic proteins [e.g., Synapsin 1 (SYN 1), postsynaptic density protein-95 (PSD-95)]. Overall, our study indicates that prenatal exposure to environmentally relevant O3 may exacerbate the symptoms of autism, shedding light on possible molecular mechanisms and providing valuable insights into the pathogenesis of autism, especially concerning low-dose levels of those pollutants.

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.

Interaction of the pre- and postnatal environment in the maternal immune activation model

Adverse influences during pregnancy are associated with a range of unfavorable outcomes for the developing offspring. Maternal psychosocial stress, exposure to infections and nutritional imbalances are known risk factors for neurodevelopmental derangements and according psychiatric and neurological manifestations later in offspring life. In this context, the maternal immune activation (MIA) model has been extensively used in preclinical research to study how stimulation of the maternal immune system during gestation derails the tightly coordinated sequence of fetal neurodevelopment. The ensuing consequence of MIA for offspring brain structure and function are majorly manifested in behavioral and cognitive abnormalities, phenotypically presenting during the periods of adolescence and adulthood. These observations have been interpreted within the framework of the "double-hit-hypothesis" suggesting that an elevated risk for neurodevelopmental disorders results from an individual being subjected to two adverse environmental influences at distinct periods of life, jointly leading to the emergence of pathology. The early postnatal period, during which the caregiving parent is the major determinant of the newborn´s environment, constitutes a window of vulnerability to external stimuli. Considering that MIA not only affects the developing fetus, but also impinges on the mother´s brain, which is in a state of heightened malleability during pregnancy, the impact of MIA on maternal brain function and behavior postpartum may importantly contribute to the detrimental consequences for her progeny. Here we review current information on the interaction between the prenatal and postnatal maternal environments in the modulation of offspring development and their relevance for the pathophysiology of the MIA model.

Endogenous oxytocin levels in children with autism: Associations with cortisol levels and oxytocin receptor gene methylation

Alterations in the brain's oxytocinergic system have been suggested to play an important role in the pathophysiology of autism spectrum disorder (ASD), but insights from pediatric populations are sparse. Here, salivary oxytocin was examined in the morning (AM) and afternoon (PM) in school-aged children with (n = 80) and without (n = 40) ASD (boys/girls 4/1), and also characterizations of DNA methylation (DNAm) of the oxytocin receptor gene (OXTR) were obtained. Further, cortisol levels were assessed to examine links between the oxytocinergic system and hypothalamic-pituitary-adrenal (HPA) axis signaling. Children with ASD displayed altered (diminished) oxytocin levels in the morning, but not in the afternoon, after a mildly stress-inducing social interaction session. Notably, in the control group, higher oxytocin levels at AM were associated with lower stress-induced cortisol at PM, likely reflective of a protective stress-regulatory mechanism for buffering HPA stress activity. In children with ASD, on the other hand, a significant rise in oxytocin levels from the morning to the afternoon was associated with a higher stress-induced cortisol release in the afternoon, likely reflective of a more reactive stress regulatory release of oxytocin for reactively coping with heightened HPA activity. Regarding epigenetic modifications, no overall pattern of OXTR hypo- or hypermethylation was evident in ASD. In control children, a notable association between OXTR methylation and levels of cortisol at PM was evident, likely indicative of a compensatory downregulation of OXTR methylation (higher oxytocin receptor expression) in children with heightened HPA axis activity. Together, these observations bear important insights into altered oxytocinergic signaling in ASD, which may aid in establishing relevant biomarkers for diagnostic and/or treatment evaluation purposes targeting the oxytocinergic system in ASD.

Epigenomic signatures reveal mechanistic clues and predictive markers for autism spectrum disorder

Autism spectrum disorder (ASD) comprises a heterogeneous group of neurodevelopmental outcomes in children with a commonality in deficits in social communication and language combined with repetitive behaviors and interests. The etiology of ASD is heterogeneous, as several hundred genes have been implicated as well as multiple in utero environmental exposures. Over the past two decades, epigenetic investigations, including DNA methylation, have emerged as a novel way to capture the complex interface of multivariate ASD etiologies. More recently, epigenome-wide association studies using human brain and surrogate accessible tissues have revealed some convergent genes that are epigenetically altered in ASD, many of which overlap with known genetic risk factors. Unlike transcriptomes, epigenomic signatures defined by DNA methylation from surrogate tissues such as placenta and cord blood can reflect past differences in fetal brain gene transcription, transcription factor binding, and chromatin. For example, the discovery of NHIP (neuronal hypoxia inducible, placenta associated) through an epigenome-wide association in placenta, identified a common genetic risk for ASD that was modified by prenatal vitamin use. While epigenomic signatures are distinct between different genetic syndromic causes of ASD, bivalent chromatin and some convergent gene pathways are consistently epigenetically altered in both syndromic and idiopathic ASD, as well as some environmental exposures. Together, these epigenomic signatures hold promising clues towards improved early prediction and prevention of ASD as well genes and gene pathways to target for pharmacological interventions. Future advancements in single cell and multi-omic technologies, machine learning, as well as non-invasive screening of epigenomic signatures during pregnancy or newborn periods are expected to continue to impact the translatability of the recent discoveries in epigenomics to precision public health.

Candidate biomarkers from the integration of methylation and gene expression in discordant autistic sibling pairs

While the genetics of autism spectrum disorders (ASD) has been intensively studied, resulting in the identification of over 100 putative risk genes, the epigenetics of ASD has received less attention, and results have been inconsistent across studies. We aimed to investigate the contribution of DNA methylation (DNAm) to the risk of ASD and identify candidate biomarkers arising from the interaction of epigenetic mechanisms with genotype, gene expression, and cellular proportions. We performed DNAm differential analysis using whole blood samples from 75 discordant sibling pairs of the Italian Autism Network collection and estimated their cellular composition. We studied the correlation between DNAm and gene expression accounting for the potential effects of different genotypes on DNAm. We showed that the proportion of NK cells was significantly reduced in ASD siblings suggesting an imbalance in their immune system. We identified differentially methylated regions (DMRs) involved in neurogenesis and synaptic organization. Among candidate loci for ASD, we detected a DMR mapping to CLEC11A (neighboring SHANK1) where DNAm and gene expression were significantly and negatively correlated, independently from genotype effects. As reported in previous studies, we confirmed the involvement of immune functions in the pathophysiology of ASD. Notwithstanding the complexity of the disorder, suitable biomarkers such as CLEC11A and its neighbor SHANK1 can be discovered using integrative analyses even with peripheral tissues.

Vasopressin, and not oxytocin, receptor gene methylation is associated with individual differences in receptive joint attention in chimpanzees (Pan troglodytes)

Joint attention (JA) is an important milestone in human infant development and is predictive of the onset of language later in life. Clinically, it has been reported that children at risk for or with a diagnosis of autism spectrum disorder (ASD) perform more poorly on measures of JA compared to neurotypical controls. JA is not unique to humans but has also been reported in great apes and to a lesser extent in more distantly related monkeys. Further, individual differences in JA among chimpanzees are associated with polymorphisms in the vasopressin and oxytocin genes, AVPR1A and OXTR. Here, we tested whether individual variation in DNA methylation of OXTR and AVPR1A were associated with performance on JA tasks in chimpanzees. We found that individual differences in JA performance was associated with AVPR1A methylation, but not OXTR methylation in the chimpanzees. The collective results provide further evidence of the role of AVPR1A in JA abilities in chimpanzees. The results further suggest that methylation values for AVPR1A may be useful biomarkers for identifying individuals at risk for ASD or related neurodevelopmental disorders associated with impairments in JA abilities.

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.

Differentiated Approach to Pharmacotherapy of Autism Spectrum Disorders: Biochemical Aspects

Autism Spectrum Disorders (ASD) are highly heterogeneous neurodevelopmental disorders caused by a complex interaction of numerous genetic and environmental factors and leading to deviations in the nervous system formation at the very early developmental stages. Currently, there are no accepted pharmacological treatments for the so-called core symptoms of ASD, such as social communication disorders and restricted and repetitive behavior patterns. Lack of knowledge about biological basis of ASD, absence of the clinically significant biochemical parameters reflecting abnormalities in the signaling cascades controlling the nervous system development and functioning, and lack of methods for selection of clinically and biologically homogeneous subgroups are considered as causes for the failure of clinical trials of ASD pharmacotherapy. This review considers the possibilities of applying differentiated clinical and biological approaches to the targeted search for ASD pharmacotherapy with emphasis on biochemical markers associated with ASD and attempts to stratify patients by biochemical parameters. The use of such approach as "the target-oriented therapy and assessment of the target status before and during the treatment to identify patients with a positive response to treatment" is discussed using the published results of clinical trials as examples. It is concluded that identification of biochemical parameters for selection of the distinct subgroups among the ASD patients requires research on large samples reflecting clinical and biological diversity of the patients with ASD, and use of unified approaches for such studies. An integrated approach, including clinical observation, clinical-psychological assessment of the patient behavior, study of medical history and description of individual molecular profiles should become a new strategy for stratifying patients with ASD for clinical pharmacotherapeutic trials, as well as for evaluating their efficiency.

Oxytocin receptor DNA methylation is associated with exogenous oxytocin needs during parturition and postpartum hemorrhage

BACKGROUND

The oxytocin receptor gene (OXTR) is regulated, in part, by DNA methylation. This mechanism has implications for uterine contractility during labor and for prevention or treatment of postpartum hemorrhage, an important contributor to global maternal morbidity and mortality.

METHODS

We measured and compared the level of OXTR DNA methylation between matched blood and uterine myometrium to evaluate blood as an indicator of uterine methylation status using targeted pyrosequencing and sites from the Illumina EPIC Array. Next, we tested for OXTR DNA methylation differences in blood between individuals who experienced a postpartum hemorrhage arising from uterine atony and matched controls following vaginal birth. Bivariate statistical tests, generalized linear modeling and Poisson regression were used in the analyses.

RESULTS

Here we show a significant positive correlation between blood and uterine DNA methylation levels at several OXTR loci. Females with higher OXTR DNA methylation in blood had required significantly more exogenous oxytocin during parturition. With higher DNA methylation, those who had oxytocin administered during labor had significantly greater relative risk for postpartum hemorrhage (IRR 2.95, 95% CI 1.53-5.71).

CONCLUSIONS

We provide evidence that epigenetic variability in OXTR is associated with the amount of oxytocin administered during parturition and moderates subsequent postpartum hemorrhage. Methylation can be measured using a peripheral tissue, suggesting potential use in identifying individuals susceptible to postpartum hemorrhage. Future studies are needed to quantify myometrial gene expression in connection with OXTR methylation.

Machine Learning-Based Blood RNA Signature for Diagnosis of Autism Spectrum Disorder

Early diagnosis of autism spectrum disorder (ASD) is crucial for providing appropriate treatments and parental guidance from an early age. Yet, ASD diagnosis is a lengthy process, in part due to the lack of reliable biomarkers. We recently applied RNA-sequencing of peripheral blood samples from 73 American and Israeli children with ASD and 26 neurotypically developing (NT) children to identify 10 genes with dysregulated blood expression levels in children with ASD. Machine learning (ML) analyzes data by computerized analytical model building and may be applied to building diagnostic tools based on the optimization of large datasets. Here, we present several ML-generated models, based on RNA expression datasets collected during our recently published RNA-seq study, as tentative tools for ASD diagnosis. Using the random forest classifier, two of our proposed models yield an accuracy of 82% in distinguishing children with ASD and NT children. Our proof-of-concept study requires refinement and independent validation by studies with far larger cohorts of children with ASD and NT children and should thus be perceived as starting point for building more accurate ML-based tools. Eventually, such tools may potentially provide an unbiased means to support the early diagnosis of ASD.

Advances in human oxytocin measurement: challenges and proposed solutions

Oxytocin, a neuropeptide known for its role in reproduction and socioemotional processes, may hold promise as a therapeutic agent in treating social impairments in patient populations. However, research has yet to uncover precisely how to manipulate this system for clinical benefit. Moreover, inconsistent use of standardized and validated oxytocin measurement methodologies-including the design and study of hormone secretion and biochemical assays-present unresolved challenges. Human studies measuring peripheral (i.e., in plasma, saliva, or urine) or central (i.e., in cerebrospinal fluid) oxytocin concentrations have involved very diverse methods, including the use of different assay techniques, further compounding this problem. In the present review, we describe the scientific value in measuring human endogenous oxytocin concentrations, common issues in biochemical analysis and study design that researchers face when doing so, and our recommendations for improving studies using valid and reliable methodologies.

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.

Social attention during object engagement: toward a cross-species measure of preferential social orienting

BACKGROUND

A central challenge in preclinical research investigating the biology of autism spectrum disorder (ASD) is the translation of ASD-related social phenotypes across humans and animal models. Social orienting, an observable, evolutionarily conserved behavior, represents a promising cross-species ASD phenotype given that disrupted social orienting is an early-emerging ASD feature with evidence for predicting familial recurrence. Here, we adapt a competing-stimulus social orienting task from domesticated dogs to naturalistic play behavior in human toddlers and test whether this approach indexes decreased social orienting in ASD.

METHODS

Play behavior was coded from the Autism Diagnostic Observation Schedule (ADOS) in two samples of toddlers, each with and without ASD. Sample 1 (n = 16) consisted of community-ascertained research participants, while Sample 2 involved a prospective study of infants at a high or low familial liability for ASD (n = 67). Coding quantified the child's looks towards the experimenter and caregiver, a social stimulus, while playing with high-interest toys, a non-social stimulus. A competing-stimulus measure of "Social Attention During Object Engagement" (SADOE) was calculated by dividing the number of social looks by total time spent playing with toys. SADOE was compared based on ASD diagnosis and differing familial liability for ASD.

RESULTS

In both samples, toddlers with ASD exhibited significantly lower SADOE compared to toddlers without ASD, with large effect sizes (Hedges' g ≥ 0.92) driven by a lower frequency of child-initiated spontaneous looks. Among toddlers at high familial likelihood of ASD, toddlers with ASD showed lower SADOE than toddlers without ASD, while SADOE did not differ based on presence or absence of familial ASD risk alone. SADOE correlated negatively with ADOS social affect calibrated severity scores and positively with the Communication and Symbolic Behavior Scales social subscale. In a binary logistic regression model, SADOE alone correctly classified 74.1% of cases, which rose to 85.2% when combined with cognitive development.

CONCLUSIONS

This work suggests that a brief behavioral measure pitting a high-interest nonsocial stimulus against the innate draw of social partners can serve as a feasible cross-species measure of social orienting, with implications for genetically informative behavioral phenotyping of social deficits in ASD and other neurodevelopmental disorders.

Affective touch in the context of development, oxytocin signaling, and autism

Touch represents one of our most important senses throughout life and particularly in the context of our social and emotional experiences. In this review, we draw on research on touch processing from both animal models and humans. Firstly, we briefly describe the cutaneous touch receptors and neural processing of both affective and discriminative touch. We then outline how our sense of touch develops and summarize increasing evidence demonstrating how essential early tactile stimulation is for the development of brain and behavior, with a particular focus on effects of tactile stimulation in infant animals and pediatric massage and Kangaroo care in human infants. Next, the potential mechanisms whereby early tactile stimulation influences both brain and behavioral development are discussed, focusing on its ability to promote neural plasticity changes and brain interhemispheric communication, development of social behavior and bonding, and reward sensitivity through modulation of growth factor, oxytocin, and opioid signaling. Finally, we consider the implications of evidence for atypical responses to touch in neurodevelopmental disorders such as autism spectrum disorder and discuss existing evidence and future priorities for establishing potential beneficial effects of interventions using massage or pharmacological treatments targeting oxytocin or other neurochemical systems.

Sex-dependent association between variability in infants' OXTR methylation at birth and negative affectivity at 3 months

BACKGROUND

Sex-specific differences in DNA methylation of the oxytocin receptor gene (OXTR) have been shown in adults and are related to several mental disorders. Negative affectivity early in life is a trans-diagnostic risk marker of later psychopathology and is partly under genetic control. However, sex-specific variations in OXTR methylation (OXTRm) in infants and their associations with negative affectivity are still unknown.

AIMS

Here, we explored sex differences in the association between infant OXTRm at birth and negative affectivity at 3 months of age.

METHODS

Infants and their mothers (N = 224) were recruited at delivery. Infants' methylation status was assessed in 13 CpG sites within the OXTR gene intron 1 region (chr3: 8810654-8810919) in buccal cells at birth while 3-month-old infants' negative affectivity was assessed by mothers using a well-validated temperament questionnaire.

RESULTS

OXTRm at 12 CpG sites was higher in females than in males. Moreover, higher infants' OXTRm at 6 specific CpG sites was associated with greater negative affectivity in males, but not in females.

CONCLUSIONS

These results provide new insights into the role of sex-dependent epigenetic mechanisms linking OXTRm with early infants' emotional development. Understanding the degree to which epigenetic processes relate to early temperamental variations may help inform the etiology of later childhood psychopathological outcomes.

Artificial neural networks reveal sex differences in gene methylation, and connections between maternal risk factors and symptom severity in autism spectrum disorder

Aim and methods: Artificial neural networks were used to unravel connections among blood gene methylation levels, sex, maternal risk factors and symptom severity evaluated using the Autism Diagnostic Observation Schedule 2 (ADOS-2) score in 58 children with autism spectrum disorder (ASD). Results: Methylation levels of MECP2, HTR1A and OXTR genes were connected to females, and those of EN2, BCL2 and RELN genes to males. High gestational weight gain, lack of folic acid supplements, advanced maternal age, preterm birth, low birthweight and living in rural context were the best predictors of a high ADOS-2 score. Conclusion: Artificial neural networks revealed links among ASD maternal risk factors, symptom severity, gene methylation levels and sex differences in methylation that warrant further investigation in ASD.

Genome-wide methylation analysis of post-mortem cerebellum samples supports the role of peroxisomes in autism spectrum disorder

Aim: We tested the hypothesis that a subset of patients with autism spectrum disorder (ASD) contains candidate genes with high DNA methylation differences (effective values) that potentially affect one of the two alleles. Materials & methods: Genome-wide DNA methylation comparisons were made on cerebellum samples from 30 patients and 45 controls. Results: 12 genes with high effective values, including GSDMD, MMACHC, SLC6A5 and NKX6-2, implicated in ASD and other neuropsychiatric disorders were identified. Monoallelic promoter methylation and downregulation were observed for SERHL (serine hydrolase-like) and CAT (catalase) genes associated with peroxisome function. Conclusion: These data are consistent with the hypothesis implicating impaired peroxisome function/biogenesis for ASD. A similar approach holds promise for identifying rare epimutations in ASD and other complex disorders.

Oxytocin and microglia in the development of social behaviour

Oxytocin is a well-established regulator of social behaviour. Microglia, the resident immune cells of the central nervous system, regulate brain development and maintenance in health and disease. Oxytocin and microglia interact: microglia appear to regulate the oxytocin system and are, in turn, regulated by oxytocin, which appears to have anti-inflammatory effects. Both microglia and oxytocin are regulated in sex-specific ways. Oxytocin and microglia may work together to promote experience-dependent circuit refinement through multiple developmental-sensitive periods contributing to individual differences in social behaviour. This article is part of the theme issue 'Interplays between oxytocin and other neuromodulators in shaping complex social behaviours'.

Autism detection based on multiple time scale model

OBJECTIVE

Current autism clinical detection relies on doctor observation and filling of clinical scales, which is subjective and easily misdetection. Existing autism research of functional magnetic resonance imaging (fMRI) over-compresses the time-scale information and has poor generalization ability. This study extracts multiple time scale brain features of fMRI, providing objective detection.

APPROACH

We first use least absolute shrinkage and selection operator (LASSO) to build a sparse network and extract features with a time scale of 1. Then, we use hidden markov model (HMM) to extract features that describe the dynamic changes of the brain, with a time scale of 2. Additionally, to analyze the features of the potential network activity of autism from a higher time scale, we use long short-term memory (LSTM) to construct an auto-encoder to re-encode the original data and extract the features of the at a higher time scale, with a time scale of T, and T is the time length of fMRI. We use Recursive Feature Elimination (RFE) for feature selection for three different time scale features, merge them into multiple time scale features, and finally use one-dimensional convolution neural network (1DCNN) for classification.

MAIN RESULTS

Compared with well-established models, our method has achieved better results. The accuracy of our method is 76.0%, and the area under the roc curve is 0.83, tested on the completely independent data, so our method has better generalization ability.

SIGNIFICANCE

This research analyzes fMRI sequences from multiple time scale to detect autism, and it also provides a new framework and research ideas for subsequent fMRI analysis.

From Genes to Therapy in Autism Spectrum Disorder

In recent years, findings from genetic and other biological studies are starting to reveal the role of various molecular mechanisms that contribute to the etiology of ASD [...]

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.