Sniffing around oxytocin: review and meta-analyses of trials in healthy and clinical groups with implications for pharmacotherapy

Fluorene-9-bisphenol acts on the gut-brain axis by regulating oxytocin signaling to disturb social behaviors in zebrafish

Previous studies have identified the exposure to ubiquitous environmental endocrine disruptors may be a risk factor of neurological disorders. However, the effects of fluorene-9-bisphenol (BHPF) in environmental exposure concentrations associated with these disorders are poorly understood. In this study, classic light-dark and social behavior tests were performed on zebrafish larvae and adults exposed BHPF exposure to evaluate social behavioral disorders and the microbiota-gut-brain axis was assessed to reveal the potential mechanisms underlying the behavioral abnormalities observed. Our results demonstrated that zebrafish larvae exposed to an environmentally relevant concentration (0.1 nM) of BHPF for 7 days showed a diminished response to external environmental factors (light or dark). Zebrafish larvae exposed to BHPF for 7 days or adults exposed to BHPF for 30 days at 1 μM displayed significant behavioral inhibition and altered social behaviors, including social recognition, social preference, and social fear contagion, indicating autism-like behaviors were induced by the exposure. BHPF exposure reduced the distribution of Nissl bodies in midbrain neurons and significantly reduced 5-hydroxytryptamine signaling. Oxytocin (OXT) levels and expression of its receptor oxtra in the gut and brain were down-regulated by BHPF exposure. In addition, the expression levels of genes related to the excitation-inhibitory balance of synaptic transmission changed. Microbiomics revealed increased community diversity and altered abundance of some microflora, such as an elevation in Bacillota and Bacteroidota and a decline in Mycoplasmatota in zebrafish guts, which might contribute to the abnormal neural circuits and autism-like behaviors induced by BHPF. Finally, the rescue effect of exogenous OXT on social behavioral defects induced by BHPF exposure was verified in zebrafish, highlighting the crucial role of OXT signaling through gut-brain axis in the regulatory mechanisms of social behaviors affected by BHPF. This study contributes to understanding the effects of environmental BHPF exposure on neuropsychiatric disorders and attracts public attention to the health risks posed by chemicals in aquatic organisms. The potential mental disorders should be considered in the safety assessments of environmental pollutants.

Expression of bond-related behaviors affects titi monkey responsiveness to oxytocin and vasopressin treatments

Social bonds influence physiology and behavior, which can shape how individuals respond to physical and affective challenges. Coppery titi monkey (Plecturocebus cupreus) offspring form selective bonds with their fathers, making them ideal for investigating how father-daughter bonds influence juveniles' responses to oxytocin (OT) and arginine-vasopressin (AVP) manipulations. We quantified the expression of father-daughter bond-related behaviors in females (n = 10) and gave acute intranasal treatments of saline, low/medium/high OT, low/high AVP, or an OT receptor antagonist (OTA) to subjects prior to a parent preference test. While females spent more time in proximity to their parents than strangers, we found a large degree of individual variation. Females with greater expression of bonding behaviors responded to OT treatments in a dose-dependent manner. Subjects also spent less time in proximity to strangers when treated with High OT (p = 0.003) and Low OT (p = 0.007), but more time when treated with High AVP (p = 0.007), Low AVP (p = 0.009), and OTA (p = 0.001). Findings from the present study suggest that variation in the expression of bond-related behaviors may alter responsiveness to OT and AVP, increasing engagement with unfamiliar social others. This enhanced sociality with strangers may promote the formation of pair bonds with partners.

Intranasal oxytocin as an adjunct treatment among patients with severe major depression with and without comorbid borderline personality disorder

INTRODUCTION

Results of studies concerning a possible beneficial effect of Intranasal-Oxytocin (IN-OT) as an add-on treatment for patients with major depression (MDD) have been inconsistent. One possible explanation to account for the difference in the effect of IN-OT is comorbid borderline personality disorder (BPD). This randomized controlled study was aimed to explore the differential effect of IN-OT administration among depressive patients with or without comorbid borderline personality disorder.

METHODS

A secondary analysis was conducted on a specific subset of patients who participated in an RCT evaluating the impact of IN-OT as add-on treatment for patients with severe mental illness. Patients treated in inpatient settings (N = 58) were randomized and double-blindly allocated to receive twice daily IN-OT (32 IU) or placebo for a period of four weeks. The effect of IN-OT on therapy process and outcome was examined among patients with (n = 35) and without (n = 23) comorbid BPD.

RESULTS

An interaction effect between diagnosis and group was observed on the Outcome Questionnaire-45 (B = 8.93, p = .007). Further analysis revealed that patients without BPD demonstrated significantly greater improvements following OT administration (B = -8.32, p = .001), whereas patients with BPD did not show significant improvement (B = 0.61, p = .76). The interactive pattern was also observed in the Hopkins Symptom Checklist (B = 0.25, p = .02), where patients without BPD demonstrated significantly larger improvements following OT administration (B = -0.29, p = .0009) as compared to placebo, while patients with BPD demonstrated no significant improvement (B = -0.04, p = .55). We did not find a harmful effect of IN-OT administration among patients with MDD and comorbid BPD.

CONCLUSIONS

Patients with MDD and comorbid BPD benefit less from IN-OT administration as compared to depressed patients without BPD. Future studies should aim to identify patients who are more likely to benefit from IN-OT administration.

Oxytocin as a transdiagnostic biomarker of well-being in severe mental illness during the Covid-19 pandemic

Individuals with severe mental illness (SMI) have been found to suffer a greater decline in psychological well-being compared to the general population in times of stress. The present study aimed to examine clinical and endocrine resilience factors of psychological well-being in SMI patients during the Covid-19 pandemic.

METHODS

After Covid-19 crisis outburst in Israel 112 participants, 69 outpatients, and 43 inpatients and day treatment patients were recruited. Outpatients signed an online informed consent and filled in questionnaires regarding their level of mental health symptoms (OQ-45), fear of Covid-19 (FCV), and psychological well-being (PWB). Inpatients answered the same questionnaires and in addition, went through a positive social interaction paradigm while providing three saliva samples to measure their s-IgA and oxytocin (OT) levels.

RESULTS

A strong negative correlation was found in the whole sample between reported mental health symptoms, fear of Covid-19, and well-being. Hierarchical regression did not find additional contribution of the fear of the pandemic in predicting well-being beyond the impact of symptomatology. For inpatients (N = 39) only, hierarchical regression found that oxytocin, but not s-IgA could explain 5% of the variance of well-being (R2 = 0.05) in individuals with SMI regardless of their mental health symptoms (R2 = 0.46) and their marital status (R2 = 0.21).

CONCLUSIONS

OT is suggested as a possible independent biological resilience factor of well-being in times of major stress among SMI patients. It is still unknown whether OT is a mediator that contributes to well-being or a biological marker that indicates the degree of beneficial social interactions.

The interplay of childhood trauma, oxytocin, and impulsivity in predicting the onset of methamphetamine use

BACKGROUND

Childhood trauma is associated with substance use disorders, including methamphetamine use disorder (MUD). Oxytocin, involved in social bonding, stress regulation, and reward processing, may influence addiction vulnerability and impulsivity in individuals with a history of childhood trauma.

OBJECTIVE

To investigate the relationships among childhood trauma, oxytocin levels, impulsivity, and the age of first methamphetamine use in individuals with MUD.

PARTICIPANTS AND SETTING

The study included 298 male participants (148 individuals with MUD and 150 healthy controls) from both probation offices and psychiatric clinics.

METHODS

Childhood trauma was assessed using the Childhood Trauma Questionnaire-Short Form (CTQ-SF), impulsivity with the Barratt Impulsiveness Scale-11 (BIS-11), and plasma oxytocin levels were obtained.

RESULTS

Individuals with MUD exhibited higher levels of childhood trauma, impulsivity, and lower plasma oxytocin levels compared to healthy controls. Childhood trauma was associated with a younger age of first methamphetamine use, higher impulsivity, and lower oxytocin levels among individuals with MUD. Plasma oxytocin levels partially mediated the relationship between childhood trauma and both the age of first methamphetamine use and impulsivity. Serial mediation analysis demonstrated that oxytocin levels and impulsivity sequentially mediated the relationship between childhood trauma and the age of first methamphetamine use.

CONCLUSIONS

The findings reveal the complex interplay among childhood trauma, oxytocin, impulsivity, and methamphetamine use, emphasizing the importance of considering these factors in prevention and intervention strategies for MUD. Future research should explore oxytocin and impulsivity-focused interventions to mitigate the effects of childhood trauma and reduce MUD development risk.

Can repeated intranasal oxytocin administration affect reduced neural sensitivity towards expressive faces in autism? A randomized controlled trial

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by difficulties in social communication and interaction. Crucial for efficient social interaction is the ability to quickly and accurately extract information from a person's face. Frequency-tagging electroencephalography (EEG) is a novel tool to quantify face-processing sensitivity in a robust and implicit manner. In terms of intervention approaches, intranasal administration of oxytocin (OT) is increasingly considered as a potential pharmacological approach for improving socio-communicative difficulties in ASD, through enhancing social salience and/or reducing (social) stress and anxiety.

METHODS

In this randomized, double-blind, placebo-controlled, mechanistic pharmaco-neuroimaging clinical trial, we implemented frequency-tagging EEG to conduct an exploratory investigation into the impact of repeated OT administration (4 weeks, 12 IU, twice daily) on neural sensitivity towards happy and fearful facial expressions in children with ASD (8-12 years old; OT: n = 29; placebo: n = 32). Neural effects were assessed at baseline, post-nasal spray (24 hr after the last nasal spray) and at a follow-up session, 4 weeks after the OT administration period. At baseline, neural assessments of children with ASD were compared with those of an age- and gender-matched cohort of neurotypical (NT) children (n = 39).

RESULTS

Children with ASD demonstrated reduced neural sensitivity towards expressive faces, as compared to NT children. Upon nasal spray administration, children with ASD displayed a significant increase in neural sensitivity at the post- and follow-up sessions, but only in the placebo group, likely reflecting an implicit learning effect. Strikingly, in the OT group, neural sensitivity remained unaffected from the baseline to the post-session, likely reflecting a dampening of an otherwise typically occurring implicit learning effect.

CONCLUSIONS

First, we validated the robustness of the frequency-tagging EEG approach to assess reduced neural sensitivity towards expressive faces in children with ASD. Furthermore, in contrast to social salience effects observed after single-dose administrations, repeated OT administration dampened typically occurring learning effects in neural sensitivity. In line with OT's social anxiolytic account, these observations possibly reflect a predominant (social) stress regulatory effect towards emotionally evocative faces after repeated OT administration.

Titi monkey father-daughter bond-related behaviors explain stress response variability

Social interactions regulate our behavior and physiology, and strong social bonds can buffer us from stress. Coppery titi monkeys (Plecturocebus cupreus) are socially monogamous South American monkeys that display strong social bonds. Infants form selective bonds with their fathers, making them ideal for studying father-daughter bonds. We established a method for quantifying variability in expression of bond-related behaviors in females (n = 12), and the present study is the second to use this method for explaining titi monkey responses to behavioral tests. We also investigated how manipulations of oxytocin (OT) and vasopressin (AVP) influenced juvenile behavior and physiology. Subjects received acute intranasal treatments of saline, low/medium/high OT, low/high AVP, or OT receptor antagonist (OTA) prior to an acute social separation. General linear mixed-effects model results revealed fathers were significant behavioral and physiological stress buffers for their daughters, as evidenced by fewer distress vocalizations (p < 0.001), less locomotion (p < 0.001), and lower plasma cortisol (p < 0.001) in a social separation paradigm. Females vocalized less if they exhibited greater expression of bond-related behaviors with their fathers as infants (p = 0.01), and this stress-buffering effect remained even when the daughter was separated from the father (p = 0.001). While treatments did not alter behaviors, OTA treatment caused the largest rise in plasma cortisol (p < 0.001), suggesting blockade of OT receptors can inhibit fathers' stress-buffering effects. Remarkably, females with greater expression of father-daughter bond-related behaviors exhibited an overall reduced physiological separation distress response (p = 0.04). Findings from the present study advance current knowledge of the neurobiological mechanisms foundational to female bonds and help inform how social disruptions may differently impact individuals based on expression of bond-related behaviors.

The Interplay of Oxytocin and Attachment in Schizophrenic Patients: An fMRI Study

BACKGROUND

Attachment theory offers an important framework for understanding interpersonal interaction experiences. In the present study, we examined the neural correlates of attachment patterns and oxytocin in schizophrenic patients (SZP) compared to healthy controls (HC) using fMRI. We assumed that male SZP shows a higher proportion of insecure attachment and an altered level of oxytocin compared to HC. On a neural level, we hypothesized that SZP shows increased neural activation in memory and self-related brain regions during the activation of the attachment system compared to HC.

METHODS

We used an event-related design for the fMRI study based on stimuli that were derived from the Adult Attachment Projective Picture System to examine attachment representations and their neural and hormonal correlates in 20 male schizophrenic patients compared to 20 male healthy controls.

RESULTS

A higher proportion of insecure attachment in schizophrenic patients compared to HC could be confirmed. In line with our hypothesis, Oxytocin (OXT) levels in SZP were significantly lower than in HC. We found increasing brain activations in SZP when confronted with personal relevant sentences before attachment relevant pictures in the precuneus, TPJ, insula, and frontal areas compared to HC. Moreover, we found positive correlations between OXT and bilateral dlPFC, precuneus, and left ACC in SZP only.

CONCLUSION

Despite the small sample sizes, the patients' response might be considered as a mode of dysregulation when confronted with this kind of personalized attachment-related material. In the patient group, we found positive correlations between OXT and three brain areas (bilateral dlPFC, precuneus, left ACC) and may conclude that OXT might modulate within this neural network in SZP.

The association between neuropeptide oxytocin and neuropsychiatric disorders after orthopedic surgery stress in older patients

BACKGROUND

The health outcomes of geriatric patients exposed to surgery were found to be enhanced by social support and stress management. The aim of this study was to characterise the relationship between oxytocin and neuropsychiatric disorders after surgery.

METHODS

A total of 132 geriatric patients aged ≥ 60 years received orthopedic surgery in the First Affiliated Hospital of Harbin Medical University (Harbin, China) were enrolled in the present study. The salivary levels of stress hormone cortisol and oxytocin were measured by enzyme-linked immunosorbent assay for the screening of the stress state and oxytocin function. Moreover, the Depression Anxiety and Stress Scale (DASS), the Geriatric Anxiety Inventory (GAI), the Geriatric Depression Scale (GDS) and the Montgomery-Åsberg Depression Rating Scale (MADRS) were conducted to identify the severity of anxiety and depression. The association between oxytocin and mental health was performed by linear regression analyses in older patients receiving orthopedic surgery. Finally, the Duke Social Support Index (DSSI) was selected to measure the social support and the potential link to mental outcomes.

RESULTS

The scores from questionnaires showed that female patients with higher social support and higher levels of oxytocin demonstrated better stress-reducing responses as reflected by lower cortisol and decreased anxiety and depression symptoms. Regression analyses revealed that there was a significant association between oxytocin and scores in DASS, GAI, GDS, MADRS and DSSI, suggesting a potential link between peripheral oxytocin function and mood outcomes after orthopedic surgery.

CONCLUSIONS

Our findings reveal that oxytocin enhances the stress-protective effects of social support and reduces anxiety and depression states under stressful circumstances, particularly in older women receiving orthopedic surgery.

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.

The Role of Oxytocin in Early-Life-Stress-Related Neuropsychiatric Disorders

Early-life stress during critical periods of brain development can have long-term effects on physical and mental health. Oxytocin is a critical social regulator and anti-inflammatory hormone that modulates stress-related functions and social behaviors and alleviates diseases. Oxytocin-related neural systems show high plasticity in early postpartum and adolescent periods. Early-life stress can influence the oxytocin system long term by altering the expression and signaling of oxytocin receptors. Deficits in social behavior, emotional control, and stress responses may result, thus increasing the risk of anxiety, depression, and other stress-related neuropsychiatric diseases. Oxytocin is regarded as an important target for the treatment of stress-related neuropsychiatric disorders. Here, we describe the history of oxytocin and its role in neural circuits and related behaviors. We then review abnormalities in the oxytocin system in early-life stress and the functions of oxytocin in treating stress-related neuropsychiatric disorders.

Effects of multiple-dose intranasal oxytocin administration on social responsiveness in children with autism: a randomized, placebo-controlled trial

BACKGROUND

Intranasal administration of oxytocin is increasingly explored as a new approach to facilitate social development and reduce disability associated with a diagnosis of autism spectrum disorder (ASD). The efficacy of multiple-dose oxytocin administration in children with ASD is, however, not well established.

METHODS

A double-blind, randomized, placebo-controlled trial with parallel design explored the effects of a 4-week intranasal oxytocin administration (12 IU, twice daily) on parent-rated social responsiveness (Social Responsiveness Scale: SRS-2) in pre-pubertal school-aged children (aged 8-12 years, 61 boys, 16 girls). Secondary outcomes included a questionnaire-based assessment of repetitive behaviors, anxiety, and attachment. Effects of oxytocin were assessed immediately after the administration period and at a follow-up, 4 weeks after the last administration. The double-blind phase was followed by a 4-week single-blind phase during which all participants received intranasal oxytocin.

RESULTS

In the double-blind phase, both the oxytocin and placebo group displayed significant pre-to-post-improvements in social responsiveness and secondary questionnaires, but improvements were not specific to the intranasal oxytocin. Notably, in the single-blind phase, participants who were first allocated to intranasal placebo and later changed to intranasal oxytocin displayed a significant improvement in social responsiveness, over and above the placebo-induced improvements noted in the first phase. Participants receiving oxytocin in the first phase also showed a significant further improvement upon receiving a second course of oxytocin, but only at the 4-week follow-up. Further, exploratory moderator analyses indicated that children who received psychosocial trainings (3 or more sessions per month) along with oxytocin administration displayed a more pronounced improvement in social responsiveness.

LIMITATIONS

Future studies using larger cohorts and more explicitly controlled concurrent psychosocial trainings are warranted to further explore the preliminary moderator effects, also including understudied populations within the autism spectrum, such as children with co-occurring intellectual disabilities.

CONCLUSIONS

Four weeks of oxytocin administration did not induce treatment-specific improvements in social responsiveness in school-aged children with ASD. Future studies are warranted to further explore the clinical efficacy of oxytocin administration paired with targeted psychosocial trainings that stimulate socio-communicative behaviors. Trial registration The trial was registered with the European Clinical Trial Registry (EudraCT 2018-000769-35) on June 7th, 2018 ( https://www.clinicaltrialsregister.eu/ctr-search/trial/2018-000769-35/BE ).

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.

Oxytocin protective effects on zebrafish larvae models of autism-like spectrum disorder

Objectives

Autism is a complicated neurodevelopmental disorder characterized by social interaction deficiencies, hyperactivity, anxiety, communication disorders, and a limited range of interests. The zebrafish (Danio rerio) is a social vertebrate used as a biomedical research model to understand social behavior mechanisms.

Materials and Methods

After spawning, the eggs were exposed to sodium valproate for 48 hr, after which the eggs were divided into eight groups. Except for the positive and control groups, there were six treatment groups based on oxytocin concentration (25, 50, and 100 μM) and time point (24 and 48 hr). Treatment was performed on days 6 and 7, examined by labeling oxytocin with fluorescein-5-isothiocyanate (FITC) and imaging with confocal microscopy and the expression levels of potential genes associated with the qPCR technique. Behavioral studies, including light-dark background preference test, shoaling behavior, mirror test, and social preference, were performed on 10, 11, 12, and 13 days post fertilization (dpf), respectively.

Results

The results showed that the most significant effect of oxytocin was at the concentration of 50 μM and the time point of 48 hr. Increased expression of shank3a, shank3b, and oxytocin receptor genes was also significant at this oxytocin concentration. Light-dark background preference results showed that oxytocin in the concentration of 50 µM significantly increased the number of crosses between dark and light areas compared with valproic acid (positive group). Also, oxytocin showed an increase in the frequency and time of contact between the two larvae. We showed a decrease in the distance in the larval group and an increase in time spent at a distance of one centimeter from the mirror.

Conclusion

Our findings showed that the increased gene expression of shank3a, shank3b, and oxytocin receptors improved autistic behavior. Based on this study some indications showed that oxytocin administration in the larval stage could significantly improve the autism-like spectrum.

A Guide for Calculating Study-Level Statistical Power for Meta-Analyses

Meta-analysis is a popular approach in the psychological sciences for synthesizing data across studies. However, the credibility of meta-analysis outcomes depends on the evidential value of studies included in the body of evidence used for data synthesis. One important consideration for determining a study’s evidential value is the statistical power of the study’s design/statistical test combination for detecting hypothetical effect sizes of interest. Studies with a design/test combination that cannot reliably detect a wide range of effect sizes are more susceptible to questionable research practices and exaggerated effect sizes. Therefore, determining the statistical power for design/test combinations for studies included in meta-analyses can help researchers make decisions regarding confidence in the body of evidence. Because the one true population effect size is unknown when hypothesis testing, an alternative approach is to determine statistical power for a range of hypothetical effect sizes. This tutorial introduces the metameta R package and web app, which facilitates the straightforward calculation and visualization of study-level statistical power in meta-analyses for a range of hypothetical effect sizes. Readers will be shown how to reanalyze data using information typically presented in meta-analysis forest plots or tables and how to integrate the metameta package when reporting novel meta-analyses. A step-by-step companion screencast video tutorial is also provided to assist readers using the R package.

Dissecting social decision-making: A spotlight on oxytocinergic transmission

Social decision-making requires the ability to balance both the interests of the self and the interests of others to survive in social environments. Empathy is essential to the regulation of this type of interaction, and it often sustains relevant prosocial behaviors such as altruism and helping behavior. In the last decade, our capacity to assess affective and empathy-like behaviors in rodents has expanded our understanding of the neurobiological substrates that underly social decision-making processes such as prosocial behaviors. Within this context, oxytocinergic transmission is profoundly implicated in modulating some of the major components of social decision-making. Thus, this review will present evidence of the association between oxytocin and empathy-like and prosocial behaviors in nonhuman animals. Then, we will dissect the involvement of oxytocinergic transmission-across different brain regions and pathways-in some of the key elements of social decision-making such as emotional discrimination, social recognition, emotional contagion, social dominance, and social memory. Evidence of the modulatory role of oxytocin on social decision-making has raised considerable interest in its clinical relevance, therefore we will also discuss the controversial findings on intranasal oxytocin administration.

Effects of single- and multiple-dose oxytocin treatment on amygdala low-frequency BOLD fluctuations and BOLD spectral dynamics in autism

Prior neuroimaging clinical trials investigating the neural effects of intranasal administration of the neuropeptide oxytocin demonstrated a key role of the amygdala in oxytocin's neuromodulatory effects. These studies mostly demonstrated the acute effects of single-dose administrations, examining task-dependent effects of oxytocin on brain activity elicited during explicit experimental tasks or stimuli presentations. The increased consideration of oxytocin as a potential ameliorating treatment in autism spectrum disorder (ASD) requires a better understanding of how multiple-dose oxytocin administration affects intrinsic, task-free, amygdala function. In this double-blind, randomized, placebo-controlled trial with between-subject design, 38 adult men with ASD underwent resting-state fMRI scanning before and after oxytocin or placebo treatment. Effects were assessed either after a single-dose administration, consisting of 24 international units, or after multiple-dose treatment, consisting of 4 weeks of once-daily nasal spray administrations. Compared to placebo, oxytocin induced a decrease in intrinsic resting-state BOLD signal amplitudes of the bilateral amygdala (fractional amplitudes of low-frequency fluctuations) and modulated cross-frequency interactions between adjacent BOLD frequency components. The right amygdala showed a pattern of reduced cross-frequency harmonicity, while the left amygdala showed a relative increase in harmonic cross-frequency interactions after oxytocin treatment. Notably, the direction and magnitude of BOLD spectral changes induced after a single-dose were qualitatively similar to treatment effects induced after multiple-dose treatment. Furthermore, the identified spectral changes in amygdalar BOLD amplitude and cross-frequency harmonicity were associated with improved feelings of tension, reflecting oxytocin's anxiolytic, stress-reducing neuromodulatory role. The observed effects of oxytocin on amygdalar BOLD spectral characteristics and associated behaviors contribute to a deeper mechanistic understanding of the intrinsic, task-free neuromodulatory dynamics that underlie single- and multiple-dose oxytocin treatment in ASD. European Clinical Trial Registry (Eudract 2014-000586-45).

Frequency-Tagging EEG of Superimposed Social and Non-Social Visual Stimulation Streams Provides No Support for Social Salience Enhancement after Intranasal Oxytocin Administration

The social salience hypothesis proposes that the neuropeptide oxytocin (OT) can impact human social behavior by modulating the salience of social cues. Here, frequency-tagging EEG was used to quantify the neural responses to social versus non-social stimuli while administering a single dose of OT (24 IU) versus placebo treatment. Specifically, two streams of faces and houses were superimposed on one another, with each stream of stimuli tagged with a particular presentation rate (i.e., 6 and 7.5 Hz or vice versa). These distinctive frequency tags allowed unambiguously disentangling and objectively quantifying the respective neural responses elicited by the different streams of stimuli. This study involved a double-blind, placebo-controlled, cross-over trial with 31 healthy adult men. Based on four trials of 60 s, we detected robust frequency-tagged neural responses in each individual, with entrainment to faces being more pronounced in lateral occipito-temporal regions and entrainment to houses being focused in medial occipital regions. However, contrary to our expectation, a single dose of OT did not modulate these stimulus-driven neural responses, not in terms of enhanced social processing nor in terms of generally enhanced information salience. Bayesian analyses formally confirmed these null findings. Possibly, the baseline ceiling level performance of these neurotypical adult participants as well as the personal irrelevance of the applied stimulation streams might have hindered the observation of any OT effect.

Intranasal oxytocin administration improves mood in new mothers with moderate low mood but not in mothers with elevated symptoms of postnatal depression: A randomised controlled trial

BACKGROUND

Oxytocin (OT) is a neuropeptide hormone that has anxiolytic and antidepressant effects, and positive effects on social affiliation and behaviour, particularly in parenting and attachment relationships. In women with postnatal depression (PND), each of these are reduced. This study investigated if OT administration reduces low mood in new mothers with PND and across the low mood spectrum.

DESIGN

A double-blind, placebo-controlled, randomised controlled-trial, within-subjects, cross-over design was conducted.

PARTICIPANTS

Mothers (N = 58) between 3 and 9 months postpartum. Participants were screened for traits of PND on the Edinburgh Postnatal Depression Scale (EPDS) and assigned into 2 groups: probable PND cases (N = 26, scoring ≥9) and controls (N = 32, scoring ≤9).

METHOD

Participants rated their current mood on the Positive and Negative Affect Scale (PANAS) at Baseline (before nasal administration), Condition 1 (after first OT/Placebo administration) and Condition 2 (after second OT/Placebo administration).

RESULTS

OT administration did not affect mood in women with PND scores above the cut-off point but significantly reduced negative mood in those scoring below the cut-off point. To explore if a subgroup was driving this, we compared participants with mild, moderate and severe scores on the EPDS. OT administration significantly reduced negative mood in women with moderate low mood scores on the EPDS.

LIMITATIONS

PND was assessed by the EPDS, rather than a clinical diagnosis.

CONCLUSION

These results illustrate individual differences in response to OT administration and suggest that OT administration may offer treatment benefit to new mothers who report moderate sub-clinical levels of depression.

Exogenous oxytocin used to induce labor has no long-term adverse effect on maternal-infant bonding: Findings from the Japan Environment and Children's Study

BACKGROUND

This study investigated the association between exogenous oxytocin use for labor induction and adverse maternal-infant bonding (MIB).

METHODS

Data on 19 700 mother-infant pairs were collected, in which the infants were live-birth singletons, born in cephalic position and at >37 weeks of gestation; the drug used to induce labor was noted. Between 2011 and 2014, Japanese pregnant women were enrolled in a nationwide prospective birth cohort study, the Japan Environment and Children's Study. The Japanese version of the Mother-to-infant Bonding Scale (MIBS-J) was administered and demographic information was collected through medical record transcripts. MIBS-J scores were obtained at one month, six months, and one year after delivery. We estimated the risk of adverse MIB between use of oxytocin and other methods for labor induction using multiple linear regression analyses; interaction and mediation analyses to assess the relationship among MIBS-J scores also followed.

RESULTS

Exogenous oxytocin was used during labor on 15 252 (77.4%) participants. After adjusting for confounders, there were no significant differences in adverse MIB between groups for which exogenous oxytocin was used and not used for labor induction.

LIMITATION

The MIBS-J scores at one and six months were compiled using five instead of 10 questions. Moreover, detailed information was unavailable; for example, the questionnaire did not ask for the dosage and timing of the drugs used to induce labor.

CONCLUSIONS

Exogenous oxytocin is a safe and vital drug to induce labor, and has been shown in this study to have no significant impact on long-term adverse MIB.

"Less is more": a dose-response account of intranasal oxytocin pharmacodynamics in the human brain

Intranasal oxytocin is attracting attention as a potential treatment for several brain disorders due to promising preclinical results. However, translating findings to humans has been hampered by remaining uncertainties about its pharmacodynamics and the methods used to probe its effects in the human brain. Using a dose-response design (9, 18 and 36 IU), we demonstrate that intranasal oxytocin-induced changes in local regional cerebral blood flow (rCBF) in the amygdala at rest, and in the covariance between rCBF in the amygdala and other key hubs of the brain oxytocin system, follow a dose-response curve with maximal effects for lower doses. Yet, the effects on local rCBF might vary by amygdala subdivision, highlighting the need to qualify dose-response curves within subregion. We further link physiological changes with the density of the oxytocin receptor gene mRNA across brain regions, strengthening our confidence in intranasal oxytocin as a valid approach to engage central targets. Finally, we demonstrate that intranasal oxytocin does not disrupt cerebrovascular reactivity, which corroborates the validity of haemodynamic neuroimaging to probe the effects of intranasal oxytocin in the human brain. DATA AVAILABILITY: Participants did not consent for open sharing of the data. Therefore, data can only be accessed from the corresponding author upon reasonable request.

The Importance of Experimental Investigation of the Peripheral Oxytocin System

Oxytocin and oxytocin receptors are synthesized in the periphery where paracrine/autocrine actions have been described alongside endocrine actions effected by central release of oxytocin from the posterior pituitary. In the female reproductive system, classical actions of uterine contraction and milk ejection from mammary glands are accompanied by actions in the ovaries where roles in steroidogenesis, follicle recruitment and ovulation have been described. Steroidogenesis, contractile activity, and gamete health are similarly affected by oxytocin in the male reproductive tract. In the cardiovascular system, a local oxytocinergic system appears to play an important cardio-protective role. This role is likely associated with emerging evidence that peripheral oxytocin is an important hormone in the endocrinology of glucose homeostasis due to its actions in adipose, the pancreas, and the largely ignored oxytocinergic systems of the adrenal glands and liver. Gene polymorphisms are shown to be associated with a number of reported traits, not least factors associated with metabolic syndrome.

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.

Early developmental exposure to bisphenol A and bisphenol S disrupts socio-cognitive function, isotocin equilibrium, and excitation-inhibition balance in developing zebrafish

Dysregulation of the oxytocinergic system and excitation/inhibition (E/I) balance in synaptic transmission and neural circuits are common hallmarks of various neurodevelopmental disorders. Several experimental and epidemiological studies have shown that perinatal exposure to endocrine-disrupting chemicals bisphenol A (BPA) and bisphenol S (BPS) may contribute to a range of childhood neurodevelopmental disorders. However, the effects of BPA and BPS on social-cognitive development and the associated mechanisms remain largely unknown. In this study, we explored the impacts of early developmental exposure (2hpf-5dpf) to environmentally relevant concentrations of BPA, and its analog BPS (0.001, 0.01, and 0.1 μM), on anxiety, social behaviors, and memory performance in 21 dpf zebrafish larvae. Our results revealed that early-life exposure to low concentrations of BPA and BPS elevated anxiety-like behavior, while fish exposed to higher concentrations of these chemicals displayed social deficits and impaired object recognition memory. Additionally, we found that co-exposure with an aromatase inhibitor antagonized BPA- and BPS-induced effects on anxiety levels and social behaviors, while the co-exposure to an estrogen receptor antagonist restored recognition memory in zebrafish larvae. These results indicate that BPA and BPS may affect social-cognitive function through distinct mechanisms. On the other hand, exposure to low BPA/BPS concentrations increased both the mRNA and protein levels of isotocin (zebrafish oxytocin) in the zebrafish brain, whereas a reduction in its mRNA level was observed at higher concentrations. Further, alterations in the transcript abundance of chloride transporters, and molecular markers of gamma-aminobutyric acid (GABA) and glutamatergic systems, were observed in the zebrafish brain, suggesting possible E/I imbalance following BPA or BPS exposure. Collectively, the results of this study demonstrate that early-life exposure to low concentrations of the environmental contaminants BPA and BPS can interfere with the isotocinergic signaling pathway and disrupts the establishment of E/I balance in the developing brain, subsequently leading to the onset of a suite of behavioral deficits and neurodevelopmental disorders.

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.

Early-life oxytocin attenuates the social deficits induced by caesarean-section delivery in the mouse

The oxytocin (OXT) system has been strongly implicated in the regulation of social behaviour and anxiety, potentially contributing to the aetiology of a wide range of neuropathologies. Birth by Caesarean-section (C-section) results in alterations in microbiota diversity in early-life, alterations in brain development and has recently been associated with long-term social and anxiety-like behaviour deficits. In this study, we assessed whether OXT intervention in the early postnatal period could reverse C-section-mediated effects on behaviour, and physiology in early life and adulthood. Following C-section or per vaginum birth, pups were administered with OXT (0.2 or 2 μg/20 μl; s.c.) or saline daily from postnatal days 1-5. We demonstrate that early postnatal OXT treatment has long-lasting effects reversing many of the effects of C-section on mouse behaviour and physiology. In early-life, high-dose OXT administration attenuated C-section-mediated maternal attachment impairments. In adulthood, low-dose OXT restored social memory deficits, some aspects of anxiety-like behaviour, and improved gastrointestinal transit. Furthermore, as a consequence of OXT intervention in early life, OXT plasma levels were increased in adulthood, and dysregulation of the immune response in C-section animals was attenuated by both doses of OXT treatment. These findings indicate that there is an early developmental window sensitive to manipulations of the OXT system that can prevent lifelong behavioural and physiological impairments associated with mode of birth.

I only have eyes for you: Oxytocin administration supports romantic attachment formation through diminished interest in close others and strangers

Animal studies confirm oxytocin's (OT) role in regulating monogamous sexual behavior in pair-bonding rodents; and human studies are beginning to translate how this highly conserved neuropeptide is implicated in romantic attachment formation. A number of studies have shown how OT promotes relationship exclusivity by diminishing interest in strangers and increasing reward response to partners. Less clear is whether these effects are modulated by romantic duration or life history factors, or if OT's social distancing effects generalize beyond strangers to close relationships. We report the results of a double-blind, placebo-controlled crossover study on the effects of a single dose of intranasal OT (24 IU) on forty-four young adults (91% female) in different stages of romantic attachment formation (M duration=21 months). Participants completed a screening survey and two lab visits separated by 4-weeks, including a diagrammatic measure of attachment to parents and peers, attitudes related to sexual conservatism and partner infidelity, ratings scales of closeness to romantic partners, and visual attractiveness ratings of strangers. Individual differences were examined by life history factors, including maternal love withdrawal and parental separation. Results indicated that OT administration decreased attachment to mothers, decreased attachment to subsidiary attachment figures, and decreased attraction to strangers. In all cases, emotional distancing was stronger among participants in newer romantic relationships. OT increased arousal to partner infidelity and increased sexual conservatism among participants with negative life history experiences (parental separation and high love withdrawal), whereas the reverse was true for participants reporting a more positive life history. Findings suggest that OT supports exclusivity through social distancing from strangers and close others within a sensitive period of attachment formation. In addition, findings indicate OT plays a different role in mate retention strategies by life history.

Practitioner's review: medication for children and adolescents with autism spectrum disorder (ASD) and comorbid conditions

Alleviating the multiple problems of children with autism spectrum disorder (ASD) and its comorbid conditions presents major challenges for the affected children, parents, and therapists. Because of a complex psychopathology, structured therapy and parent training are not always sufficient, especially for those patients with intellectual disability (ID) and multiple comorbidities. Moreover, structured therapy is not available for a large number of patients, and pharmacological support is often needed, especially in those children with additional attention deficit/hyperactivity and oppositional defiant, conduct, and sleep disorders.

Salivary oxytocin, cognitive anxiety and self-confidence in pre-competition athletes

It is well known that soccer sport has the potential for high levels of stress and anxiety and that these are linked to Cortisol (C) variations. To date, much research has been devoted to understanding how Oxytocin (OT) can affect anxiety in response to a challenge. The aim of this study was to investigate, in 56 young male soccer players, the psychophysiological stress response 96 and 24 h before one soccer match of a tournament, in order to establish whether athletes who won or lost, show different levels of C and OT or expressions of competitive state anxiety subcomponents. We found that winners had significantly lower Cognitive anxiety and higher Self-confidence scores than losers. Also, significant differences between winners and losers in C and OT concentrations were observed, with higher OT levels in who has won and higher C levels in who has lost. Our results showed interesting associations between OT, C, anxiety feelings, and the outcome of competition.

H2S and Oxytocin Systems in Early Life Stress and Cardiovascular Disease

Today it is well established that early life stress leads to cardiovascular programming that manifests in cardiovascular disease, but the mechanisms by which this occurs, are not fully understood. This perspective review examines the relevant literature that implicates the dysregulation of the gasomediator hydrogen sulfide and the neuroendocrine oxytocin systems in heart disease and their putative mechanistic role in the early life stress developmental origins of cardiovascular disease. Furthermore, interesting hints towards the mutual interaction of the hydrogen sulfide and OT systems are identified, especially with regards to the connection between the central nervous and the cardiovascular system, which support the role of the vagus nerve as a communication link between the brain and the heart in stress-mediated cardiovascular disease.

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.

Empathy and Hormonal Changes as Predictors of Sensitive Responsiveness towards Infant Crying: A Study Protocol

Sensitive responsiveness refers to parents' ability to recognize and respond to infants' cues and has been linked to parental empathy. Additionally, oxytocin (OT) and vasopressin (AVP) are hormones important for sensitivity and empathy. The aim of this study is to test the links between dispositional empathy along with changing OT and AVP levels and responsiveness to a life-like doll in couples and to verify whether these factors are predictors of responsiveness to a child's cues. Exploratory analyses include predictors of sensitive responsiveness: polymorphisms of OXTR, AVPR1a and CD38 genes, personal characteristics and relational factors. The project employs standardized experimental settings that can be used with non-parents and the assessment of parental sensitive responsiveness towards their child. The participants are couples expecting their first child (111) and childless couples (110). The procedure involves caretaking of a life-like doll. Salivary samples and questionnaire data are collected in a planned manner. In the second part, the expectant couples are invited for the assessment of their sensitivity to their own child (Free Play episodes). Parental sensitivity is assessed using the Ainsworth Sensitivity Scale. This paper presents an interdisciplinary research project that reaches beyond the questionnaire measurement, considering many factors influencing the dynamics of adult-infant interaction.

Delivering Clinically on Our Knowledge of Oxytocin and Sensory Stimulation: The Potential of Infant Carrying in Primary Prevention

Oxytocin (OT) is one of the most intensively researched neuropeptides during the three past decades. In benign social contexts, OT exerts a range of desirable socioemotional, stress-reducing, and immunoregulatory effects in mammals and humans and influences mammalian parenting. Consequentially, research in potential pharmacological applications of OT toward human social deficits/disorders and physical illness has increased substantially. Regrettably, the results from the administration of exogenous OT are still relatively inconclusive. Research in rodent maternal developmental programming has demonstrated the susceptibility of offspring endogenous OT systems to maternal somatosensory stimulation, with consequences for behavioral, epigenetic, cognitive, and neurological outcomes. A translation of this animal research into practically feasible human parenting recommendations has yet to happen, despite the significant prevention potential implied by the maternal developmental programming research. Extended physical contact with full-term healthy infants in the months following birth (infant carrying) might constitute the human equivalent of those specific rodent maternal behaviors, found to positively influence emerging OT systems. Findings from both OT and maternal programming research parallel those found for infants exposed to such extended parental physical contact, whether through skin-to-skin contact or infant carrying. Clinical support of parents to engage in extended physical contact represents a feasible intervention to create optimum conditions for the development of infant OT systems, with potential beneficial long-term health effects.

Neural and Molecular Contributions to Pathological Jealousy and a Potential Therapeutic Role for Intranasal Oxytocin

Romantic jealousy, especially in its pathological form, is a significant contributor to both domestic abuse, including partner sexual coercion and even murder, although relatively little research has been conducted on it. Both obsessive and delusional forms have been identified although only the latter is currently recognized as a pathological disorder. Studies in both clinical and healthy populations have identified altered fronto-striatal responsivity as being associated primarily with romantic jealousy and to date drug based treatments have targeted both dopaminergic and serotonergic systems. However, there is increasing interest in a potential role for the neuropeptide oxytocin, which can also modulate dopaminergic and serotonin systems in the brain and has been shown to altered in other psychotic conditions, such as schizophrenia and obsessive compulsive disorder. Recent studies in healthy populations have reported that when oxytocin is administered intranasally it can influence the brain to promote strengthening of romantic bonds and reduce romantic jealousy in both men and women evoked in either imagined or real contexts. These findings indicate a possible therapeutic use of intranasal oxytocin administration in pathological jealousy.

Oxytocin promotes prosocial behavior and related neural responses in infant macaques at-risk for compromised social development

Although positive effects of oxytocin (OT) on social functioning are well-demonstrated, little is known about the mechanisms through which OT may drive early social development, or its therapeutic efficacy in infancy. To address these critical issues, we investigated the effects of exogenous OT on neural (EEG) and behavioral responses during observation of live facial gestures in infant macaques with limited social exposure (i.e. nursery-reared). Three key findings were revealed. First, OT increased alpha suppression over posterior scalp regions during observation of facial gestures but not non-biological movement, suggesting that OT targets self-other matching and attentional cortical networks involved in social perception from very early infancy. Second, OT increased infant production of matching facial gestures and attention towards the most socially-relevant facial stimuli, both behaviors typically silenced by early social deprivation. Third, infants with higher cortisol levels appeared to benefit the most from OT, displaying greater improvements in prosocial behaviors after OT administration. Altogether, these findings suggest that OT promotes prosocial behaviors and associated neural responses likely impacted by early social adversity, and demonstrate the potential of OT administration to ameliorate social difficulties in the context of neurodevelopmental and early-emerging psychiatric disorders, at a developmental stage when brain plasticity is greatest.

Oxytocin in Schizophrenia: Pathophysiology and Implications for Future Treatment

Schizophrenia is a form of mental disorder that is behaviorally characterized by abnormal behavior, such as social function deficits or other behaviors that are disconnected from reality. Dysregulation of oxytocin may play a role in regulating the expression of schizophrenia. Given oxytocin’s role in social cognition and behavior, a variety of studies have examined the potential clinical benefits of oxytocin in improving the psychopathology of patients with schizophrenia. In this review, we highlight the evidence for the role of endogenous oxytocin in schizophrenia, from animal models to human studies. We further discuss the potential of oxytocin as a therapeutic agent for schizophrenia and its implication in future treatment.

Changes in endogenous oxytocin levels after intranasal oxytocin treatment in adult men with autism: An exploratory study with long-term follow-up

Intranasal administration of the neuropeptide oxytocin (OT) is increasingly explored as a potential treatment for targeting the core symptoms of autism spectrum disorder (ASD). Previously, interactions of exogenously administered OT with its endogenous production have been demonstrated following single-dose administrations. However, the impact of repeated, long-term OT use on endogenous salivary OT levels is unknown. In this double-blind, randomized, placebo-controlled study with between-subject design, 34 adult men with ASD were either assigned to a four-week treatment of once-daily intranasal OT administrations (24 IU) or placebo. Salivary OT samples were obtained before and after the treatment period as well as at two follow-up sessions, four weeks and one year after cessation of the treatment. Receiving OT intranasally but not placebo reliably increased endogenous salivary levels of OT immediately post-treatment and at the follow-up session four weeks post treatment, indicating an interaction between exogenously administered OT and its endogenous production. Notably, increases in salivary OT at the four-week follow-up session were most pronounced in individuals with larger behavioral improvements in ASD social symptoms. These results suggest that OT's positive effects on social behaviors may lead to a self-perpetuating elevation of OT levels through a feed-forward triggering of its own release. Together, the current investigation provides initial evidence that repeated intranasal administration of OT can induce long-lasting changes in endogenous salivary OT levels, presumably through a positive spiral of OT release.

Navigating Motivation: A Semantic and Subjective Atlas of 7 Motives

Research from psychology, neurobiology and behavioral economics indicates that a binary view of motivation, based on approach and avoidance, may be too reductive. Instead, a literature review suggests that at least seven distinct motives are likely to affect human decisions: "consumption/resource seeking," "care," "affiliation," "achievement," "status-power," "threat approach" (or anger), and "threat avoidance" (or fear). To explore the conceptual distinctness and relatedness of these motives, we conducted a semantic categorization task. Here, participants were to assign provided words to one of the motives. By applying principal component analysis to the categorization assignments we represent the semantic inter-relations of these motives on a two-dimensional space, a "semantic atlas." This atlas suggests that, while care and affiliation are conceptually close, affiliation is closer to threat avoidance (or fear); opposite to these motives we find achievement, consumption and power, with the latter lying closer to threat approach (or anger). In a second study, we asked participants to rate how well the motive-specific words obtained in the first study described their currently experienced feelings. We find that semantically close motives are also more likely to be experienced together, that is, we replicate most of the semantic relations in the "subjective atlas." We discuss our findings in comparison to other multi-dimensional models of motivation, which show clear similarities. In addition to these motivational atlases, we provide a database of motive-specific words, together with the valence and arousal scores. These can be used for future research on the influence of motives on decision making.

Oxytocin modulates local topography of human functional connectome in healthy men at rest

Oxytocin has recently received remarkable attention for its role as a modulator of human behaviour. Here, we aimed to expand our knowledge of the neural circuits engaged by oxytocin by investigating the effects of intranasal and intravenous oxytocin on the functional connectome at rest in 16 healthy men. Oxytocin modulates the functional connectome within discrete neural systems, but does not affect the global capacity for information transfer. These local effects encompass key hubs of the oxytocin system (e.g. amygdala) but also regions overlooked in previous hypothesis-driven research (i.e. the visual circuits, temporal lobe and cerebellum). Increases in levels of oxytocin in systemic circulation induce broad effects on the functional connectome, yet we provide indirect evidence supporting the involvement of nose-to-brain pathways in at least some of the observed changes after intranasal oxytocin. Together, our results suggest that oxytocin effects on human behaviour entail modulation of multiple levels of brain processing distributed across different systems.

Intrinsic, dynamic and effective connectivity among large-scale brain networks modulated by oxytocin

The neuropeptide oxytocin is a key modulator of social-emotional behavior and its intranasal administration can influence the functional connectivity of brain networks involved in the control of attention, emotion and reward reported in humans. However, no studies have systematically investigated the effects of oxytocin on dynamic or directional aspects of functional connectivity. The present study employed a novel computational framework to investigate these latter aspects in 15 oxytocin-sensitive regions using data from randomized placebo-controlled between-subject resting state functional MRI studies incorporating 200 healthy subjects. In order to characterize the temporal dynamics, the 'temporal state' was defined as a temporal segment of the whole functional MRI signal which exhibited a similar functional interaction pattern among brain regions of interest. Results showed that while no significant effects of oxytocin were found on brain temporal state related characteristics (including temporal state switching frequency, probability of transitions between neighboring states, and averaged dwell time on each state) oxytocin extensively (n = 54 links) modulated effective connectivity among the 15 regions. The effects of oxytocin were primarily characterized by increased effective connectivity both between and within emotion, reward, salience, attention and social cognition processing networks and their interactions with the default mode network. Top-down control over emotional processing regions such as the amygdala was particularly affected. Oxytocin also increased effective homotopic interhemispheric connectivity in almost all these regions. Additionally, the effects of oxytocin on effective connectivity were sex-dependent, being more extensive in males. Overall, these findings suggest that modulatory effects of oxytocin on both within- and between-network interactions may underlie its functional influence on social-emotional behaviors, although in a sex-dependent manner. These findings may be of particular relevance to potential therapeutic use of oxytocin in psychiatric disorders associated with social dysfunction, such as autism spectrum disorder and schizophrenia, where directionality of treatment effects on causal interactions between networks may be of key importance .

Intranasal oxytocin attenuates insula activity in response to dynamic angry faces

The effects of intranasal oxytocin on amygdala activity during emotional perception are often mixed. Given that the brain is organized into networks of interconnected areas, functional connectivity might provide an effective way to further understand the oxytocin effect. The aim of the present study was to investigate whether oxytocin administration affects amygdala activity and its functional connectivity during dynamic facial expression perception. Using a between-group, double-blind, placebo-controlled design, 55 participants were randomly assigned to groups receiving a single dose of 24 IU oxytocin or a placebo via intranasal administration. An implicit emotional task was employed to investigate the effect of oxytocin on neural responses to dynamic angry, neutral, and happy facial expressions with fMRI. Participants were instructed to respond only when the inverted dynamic faces were presented. The results indicated that oxytocin attenuated activation of insula and emotional processing-related regions (e.g., ACC, thalamus, and MFG) during the viewing of dynamic angry faces. However, functional connectivity between the regions involved in the perception of dynamic angry faces was not changed following oxytocin administration. The present findings may contribute to our understanding of the anxiolytic effects of oxytocin and eventually facilitate human clinical applications.

Oxytocin treatment attenuates amygdala activity in autism: a treatment-mechanism study with long-term follow-up

Intranasal administration of the neuropeptide oxytocin (IN-OT) is increasingly considered as a potential treatment for targeting the core symptoms of autism spectrum disorder (ASD), but the effects of continual use on neural substrates are fairly unexplored and long-term effects are unknown. In this double-blind, randomized, placebo-controlled study, we investigated the effects of single-dose and multiple-dose IN-OT treatment (4 weeks of daily (24 IU) administrations) on brain activity related to processing emotional states. Thirty-eight adult men with ASD (aged between 18 and 35 years) underwent functional magnetic resonance imaging of the posterior superior temporal gyrus (pSTS) and amygdala regions while processing emotional states from point-light biological motion. In line with prior research, a single dose of IN-OT induced a reliable increase in pSTS brain activity during the processing of point-light biological motion, but no consistent long-term changes in pSTS activity were induced after the multiple-dose treatment. In terms of bilateral amygdala, the multiple-dose treatment induced a consistent attenuation in brain activity, which outlasted the period of actual administrations until four weeks and one year post-treatment. Critically, participants with stronger attenuations in amygdala-activity showed greater behavioral improvements, particularly in terms of self-reported feelings of avoidant attachment and social functioning. Together, these observations provide initial insights into the long-lasting neural consequences of chronic IN-OT use on amygdala functioning and provide first indications that the acute versus chronic effects of IN-OT administration may be qualitatively different. Larger studies are however warranted to further elucidate the long-term impact of IN-OT treatment on human neural substrates and its behavioral consequences.

Oxytocin does not improve emotional prosody recognition in schizophrenia-spectrum disorders

Schizophrenia-spectrum disorders (SSD) are associated with deficits in emotional prosody recognition. Whether administration of oxytocin can improve emotional prosody recognition accuracy in SSD is unknown. Sixty individuals with SSD and ninety-seven controls completed a placebo-controlled, double-blind, cross-over trial examining the effects of oxytocin on emotional prosody recognition accuracy. Compared to controls, SSD was associated with poorer emotional prosody recognition accuracy, regardless of stimulus valence or intensity, suggesting a generalized deficit. Oxytocin had no effect on emotional prosody recognition in either group, which is consistent with previous work suggesting that oxytocin only improves high-level social cognition in SSD.

•

Deficits in emotional prosody recognition (EPR) are common across the course of schizophrenia-spectrum disorders (SSD).

•

Oxytocin (OT) has been shown to improve aspects of social cognition and may ameliorate deficits in EPR.

•

Individuals with and without SSD completed an EPR task after receiving OT or placebo in a cross-over design over two visits.

•

Individuals with SSD had poorer EPR than controls.

•

Oxytocin did not improve EPR in either group.

Face individual identity recognition: a potential endophenotype in autism

BACKGROUND

Face individual identity recognition skill is heritable and independent of intellectual ability. Difficulties in face individual identity recognition are present in autistic individuals and their family members and are possibly linked to oxytocin polymorphisms in families with an autistic child. While it is reported that developmental prosopagnosia (i.e., impaired face identity recognition) occurs in 2-3% of the general population, no prosopagnosia prevalence estimate is available for autism. Furthermore, an autism within-group approach has not been reported towards characterizing impaired face memory and to investigate its possible links to social and communication difficulties.

METHODS

The present study estimated the prevalence of prosopagnosia in 80 autistic adults with no intellectual disability, investigated its cognitive characteristics and links to autism symptoms' severity, personality traits, and mental state understanding from the eye region by using standardized tests and questionnaires.

RESULTS

More than one third of autistic participants showed prosopagnosia. Their face memory skill was not associated with their symptom's severity, empathy, alexithymia, or general intelligence. Face identity recognition was instead linked to mental state recognition from the eye region only in autistic individuals who had prosopagnosia, and this relationship did not depend on participants' basic face perception skills. Importantly, we found that autistic participants were not aware of their face memory skills.

LIMITATIONS

We did not test an epidemiological sample, and additional work is necessary to establish whether these results generalize to the entire autism spectrum.

CONCLUSIONS

Impaired face individual identity recognition meets the criteria to be a potential endophenotype in autism. In the future, testing for face memory could be used to stratify autistic individuals into genetically meaningful subgroups and be translatable to autism animal models.

Serine-Selective Bioconjugation

This Communication reports the first general method for rapid, chemoselective, and modular functionalization of serine residues in native polypeptides, which uses a reagent platform based on the P(V) oxidation state. This redox-economical approach can be used to append nearly any kind of cargo onto serine, generating a stable, benign, and hydrophilic phosphorothioate linkage. The method tolerates all other known nucleophilic functional groups of naturally occurring proteinogenic amino acids. A variety of applications can be envisaged by this expansion of the toolbox of site-selective bioconjugation methods.

Social Support and Antibody Responses to Vaccination: A Meta-Analysis

BACKGROUND

Social support and social integration have been linked to lower rates of morbidity and mortality. However, the biological mechanisms responsible for such links need greater attention. Vaccine paradigms provide an integrative window into immune system involvement in the protective influence of social support/integration.

PURPOSE

The main aim of this article was to conduct a meta-analytic review of the association between social support/social integration and antibody responses to vaccines. Exploratory analyses also examined effect sizes and confidence intervals as a function of several factors to inform future research.

METHOD

A literature search was conducted using the ancestry approach and with PsycInfo, Medline, and the Psychology and Behavioral Science Collection by crossing the exact keywords of social support or social integration with vaccine or antibodies. The review identified nine studies with a total of 672 participants.

RESULTS

The omnibus meta-analysis showed that social support/social integration was related to higher antibody levels following vaccination, but the average effect size was small and the lower bound of the confidence interval included zero (Zr = 0.06 [-.04, .15]). These results did not appear to differ much as a function of the operationalization of social relationships, participant age, or follow-up period, although effect sizes appeared larger for studies using a primary antigen.

CONCLUSIONS

These data provide some evidence that social support may be linked to antibody responses to vaccines. However, effect sizes are mostly small and zero overall effect cannot be ruled out. Future studies would benefit from larger sample sizes and greater consideration of methodological issues associated with secondary immune responses to antigen.

Oxytocin effects on resting-state heart rate variability in women: The role of childhood rearing experiences

Oxytocin is known for its stress-reducing effects and has been associated with autonomic nervous system measures (ANS) involved in the stress response, such as heart rate variability (HRV). The current study examined the effects of intranasal oxytocin on HRV among women (oxytocin N ​= ​87, placebo N ​= ​86) during rest. Results show that oxytocin reduced RMSSD and low frequency (LF)-HRV, but only in women with positive childhood rearing experiences, and not in women with negative childhood experiences. These findings suggest that oxytocin plays a role in ANS regulation and that childhood rearing experiences may influence oxytocin effects on this stress regulating system.

•

Oxytocin reduces resting-state HRV in women without the history of a negative childhood rearing style.

•

Oxytocin reduces RMSSD and low frequency HRV during rest.

•

Oxytocin effects on HRV are absent after negative childhood experiences.

Oxytocin and vasopressin modulation of prisoner's dilemma strategies

BACKGROUND

The neuropeptides oxytocin and vasopressin have been repeatedly implicated in social decision making by enhancing social salience and, generally, cooperation. The iterated and sequential version of the prisoner's dilemma (PD) game is a social dilemma paradigm eliciting strategies of cooperation versus competition.

AIMS

We aimed to characterise the role of PD players' sex, game partner type (computer vs. human) and oxytocin or vasopressin inhalation on the player's strategy preference.

METHODS

Participants (153 men; 151 women) were randomised to intranasal 24 IU oxytocin, 20 IU vasopressin or placebo, double-blind, and played the PD. We examined main and interactive effects of sex, drug and partner type on strategy preference.

RESULTS

We found a pervasive preference for a tit-for-tat strategy (i.e. general sensitivity to the partner's choices) over unconditional cooperation, particularly when against a human rather than a computer partner. Oxytocin doubled this sensitivity in women (i.e. the preference for tit-for-tat over unconditional cooperation strategies) when playing against computers, which suggests a tendency to anthropomorphise them, and doubled women's unconditional cooperation preference when playing against humans. Vasopressin doubled sensitivity to the partner's previous choices (i.e. for tit-for-tat over unconditional cooperation) across sexes and partner types.

CONCLUSIONS

These findings suggest that women may be more sensitive to oxytocin's social effects of anthropomorphism of non-humans and of unconditional cooperation with humans, which may be consistent with evolutionary pressures for maternal care, and that vasopressin, irrespective of sex and partner type, may be generally sensitising humans to others' behaviour.