Sex- and context-dependent effects of oxytocin on social sharing

Intranasal oxytocin as a treatment for anxiety and autism: From subclinical to clinical applications

Animal and human studies have demonstrated that intranasal oxytocin (OT) can penetrate the brain and induce cognitive, emotional, and behavioral changes, particularly in social functioning. Consequently, numerous investigations have explored the potential of OT as a treatment for anxiety and autism, conditions characterized by social deficits. Although both subclinical and clinical studies provide converging evidence of the therapeutic effects of OT in reducing anxiety levels and improving social symptoms in autism, results are not always consistent. Additionally, the pharmacological mechanism of OT requires further elucidation for its effective clinical application. Therefore, this review aims to examine the contentious findings concerning the effects of OT on anxiety and autism, offer interpretations of the inconsistent results from the perspectives of individual differences and varying approaches to OT administration, and shed light on the underlying mechanisms of OT. Ultimately, standardization of dosage, frequency of administration, formulation characteristics, and nasal spray devices is proposed as essential for future human studies and clinical applications of OT treatment.

Oxytocin predicts positive affect gains in a role-play interaction

Introduction

Role-play, a key creative process in theatre, is used in therapeutic interventions to improve social skills, emotion regulation, and memory. Although role-play is widely used as a psychotherapeutic technique, its mechanisms of action are not fully understood.

Methods

Our study introduces a standardized controlled procedure for promoting role-play in the laboratory based on the portrayal of a fictional persona and examines its effects on anxiety, affect, prosocial attitudes, and salivary oxytocin dynamics in 38 participants.

Results

In our experiment, role-play significantly increased positive affect and prosocial attitudes and decreased anxiety compared to a control condition. Basal salivary oxytocin levels predicted higher gains in positive affect following role-play, suggesting a specific moderating effect of oxytocin. The fictional persona used in the procedure was rated as very happy by subjects, creating a positive social context for the role-play social interaction.

Discussions

We propose that the observed moderation effect of oxytocin in our study is specific to the role-play condition due to the capacity of role-play to generate an affective regulatory context based on congruency toward the emotional state of the fictional persona. Our findings indicate that basal oxytocin levels could predict specific outcomes of role-play in therapeutical setting. We discuss several psychological and biological mechanisms that could account for the observed effects of role-play and how oxytocin could act as a substrate for them.

The central renin-angiotensin system: A genetic pathway, functional decoding, and selective target engagement characterization in humans

Accumulating evidence suggests that the brain renin angiotensin system (RAS) plays a pivotal role in the regulation of cognition and behavior as well as in the neuropathology of neurological and mental disorders. The angiotensin II type 1 receptor (AT1R) mediates most functional and neuropathology-relevant actions associated with the central RAS. However, an overarching comprehension to guide translation and utilize the therapeutic potential of the central RAS in humans is currently lacking. We conducted a comprehensive characterization of the RAS using an innovative combination of transcriptomic gene expression mapping, image-based behavioral decoding, and pre-registered randomized controlled discovery-replication pharmacological resting-state functional magnetic resonance imaging (fMRI) trials (N = 132) with a selective AT1R antagonist. The AT1R exhibited a particular dense expression in a subcortical network encompassing the thalamus, striatum, and amygdalo-hippocampal formation. Behavioral decoding of the AT1R gene expression brain map showed an association with memory, stress, reward, and motivational processes. Transient pharmacological blockade of the AT1R further decreased neural activity in subcortical systems characterized by a high AT1R expression, while increasing functional connectivity in the cortico-basal ganglia-thalamo-cortical circuitry. Effects of AT1R blockade on the network level were specifically associated with the transcriptomic signatures of the dopaminergic, opioid, acetylcholine, and corticotropin-releasing hormone signaling systems. The robustness of the results was supported in an independent pharmacological fMRI trial. These findings present a biologically informed comprehensive characterization of the central AT1R pathways and their functional relevance on the neural and behavioral level in humans.

The effect of intranasal oxytocin on social reward processing in humans: a systematic review

Understanding the neurobiology of social reward processing is fundamental, holding promises for reducing maladaptive/dysfunctional social behaviors and boosting the benefits associated with a healthy social life. Current research shows that processing of social (vs. non-social) rewards may be driven by oxytocinergic signaling. However, studies in humans often led to mixed results. This review aimed to systematically summarize available experimental results that assessed the modulation of social reward processing by intranasal oxytocin (IN-OXY) administration in humans. The literature search yielded 385 results, of which 19 studies were included in the qualitative synthesis. The effects of IN-OXY on subjective, behavioral, and (neuro)physiological output variables are discussed in relation to moderating variables-reward phase, reward type, onset and dosage, participants' sex/gender, and clinical condition. Results indicate that IN-OXY is mostly effective during the consumption ("liking") of social rewards. These effects are likely exerted by modulating the activity of the prefrontal cortex, insula, precuneus, anterior cingulate cortex, amygdala, and striatum. Finally, we provide suggestions for designing future oxytocin studies.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021278945, identifier CRD42021278945.

Evaluating the efficacy of oxytocin for pain management: An updated systematic review and meta-analysis of randomized clinical trials and observational studies

Background

There is a need for novel analgesics with favorable risk to benefit profiles. Oxytocin has recently gained attention for its potential analgesic properties.

Aim

The aim of this study was to perform an updated systematic review and meta-analysis evaluating the effect of oxytocin for pain management.

Method

Ovid MEDLINE, Embase, PsycINFO, CINAHL, and Clinicaltrials.gov were searched for articles reporting on associations between oxytocin and chronic pain management from January 2012 to February 2022. Studies published before 2012 that were identified in our previous systematic review were also eligible. Risk of bias of included studies was assessed. Synthesis of results was performed using meta-analysis and narrative synthesis.

Results

Searches returned 2087 unique citations. In total, 14 articles were included that reported on 1504 people living with pain. Results from meta-analysis and narrative review were mixed. Meta-analysis of three studies indicated that exogenous oxytocin administration did not result in a significant reduction in pain intensity relative to placebo (N = 3; n = 95; g = 0.31; 95% confidence interval [CI] -0.10, 0.73). Narrative review provided encouraging evidence that exogenous oxytocin administration reduced pain sensitivity among individuals with back pain, abdominal pain, and migraines. Results suggested that individual difference factors (e.g., sex and chronic pain condition) may influence oxytocin-induced nociception, but the heterogeneity and limited number of studies identified precluded further investigation.

Discussion

There is equipoise for the benefit of oxytocin for pain management. Future studies are imperative and should undertake more precise exploration of potential confounds and mechanisms of analgesic action to clarify inconsistency in the literature.

l-DOPA and oxytocin influence the neurocomputational mechanisms of self-benefitting and prosocial reinforcement learning

Humans learn through reinforcement, particularly when outcomes are unexpected. Recent research suggests similar mechanisms drive how we learn to benefit other people, that is, how we learn to be prosocial. Yet the neurochemical mechanisms underlying such prosocial computations remain poorly understood. Here, we investigated whether pharmacological manipulation of oxytocin and dopamine influence the neurocomputational mechanisms underlying self-benefitting and prosocial reinforcement learning. Using a double-blind placebo-controlled cross-over design, we administered intranasal oxytocin (24 IU), dopamine precursor l-DOPA (100 mg + 25 mg carbidopa), or placebo over three sessions. Participants performed a probabilistic reinforcement learning task with potential rewards for themselves, another participant, or no one, during functional magnetic resonance imaging. Computational models of reinforcement learning were used to calculate prediction errors (PEs) and learning rates. Participants behavior was best explained by a model with different learning rates for each recipient, but these were unaffected by either drug. On the neural level, however, both drugs blunted PE signaling in the ventral striatum and led to negative signaling of PEs in the anterior mid-cingulate cortex, dorsolateral prefrontal cortex, inferior parietal gyrus, and precentral gyrus, compared to placebo, and regardless of recipient. Oxytocin (versus placebo) administration was additionally associated with opposing tracking of self-benefitting versus prosocial PEs in dorsal anterior cingulate cortex, insula and superior temporal gyrus. These findings suggest that both l-DOPA and oxytocin induce a context-independent shift from positive towards negative tracking of PEs during learning. Moreover, oxytocin may have opposing effects on PE signaling when learning to benefit oneself versus another.

Angiotensin II Regulates the Neural Expression of Subjective Fear in Humans: A Precision Pharmaco-Neuroimaging Approach

BACKGROUND

Rodent models and pharmacological neuroimaging studies in humans have been used to test novel pharmacological agents to reduce fear. However, these strategies are limited with respect to determining process-specific effects on the actual subjective experience of fear, which represents the key symptom that motivates patients to seek treatment. In this study, we used a novel precision pharmacological functional magnetic resonance imaging approach based on process-specific neuroaffective signatures to determine effects of the selective angiotensin II type 1 receptor (AT1R) antagonist losartan on the subjective experience of fear.

METHODS

In a double-blind, placebo-controlled, randomized pharmacological functional magnetic resonance imaging design, healthy participants (N = 87) were administered 50 mg losartan or placebo before they underwent an oddball paradigm that included neutral, novel, and fear oddballs. Effects of losartan on brain activity and connectivity as well as on process-specific multivariate neural signatures were examined.

RESULTS

AT1R blockade selectively reduced neurofunctional reactivity to fear-inducing visual oddballs in terms of attenuating dorsolateral prefrontal activity and amygdala-ventral anterior cingulate communication. Neurofunctional decoding further demonstrated fear-specific effects in that AT1R blockade reduced the neural expression of subjective fear but not of threat or nonspecific negative affect and did not influence reactivity to novel oddballs.

CONCLUSIONS

These results show a specific role of the AT1R in regulating the subjective fear experience and demonstrate the feasibility of a precision pharmacological functional magnetic resonance imaging approach to the affective characterization of novel receptor targets for fear in humans.

The Angiotensin Antagonist Losartan Modulates Social Reward Motivation and Punishment Sensitivity via Modulating Midbrain-Striato-Frontal Circuits

Social deficits and dysregulations in dopaminergic midbrain-striato-frontal circuits represent transdiagnostic symptoms across psychiatric disorders. Animal models suggest that interactions between the dopamine (DA) and renin-angiotensin system (RAS) may modulate learning and reward-related processes. The present study therefore examined the behavioral and neural effects of the Angiotensin II type 1 receptor (AT1R) antagonist losartan on social reward and punishment processing in humans. A preregistered randomized double-blind placebo-controlled between-subject pharmacological design was combined with a social incentive delay (SID) functional MRI (fMRI) paradigm during which subjects could avoid social punishment or gain social reward. Healthy volunteers received a single-dose of losartan (50 mg, n = 43, female = 17) or placebo (n = 44, female = 20). We evaluated reaction times (RTs) and emotional ratings as behavioral and activation and functional connectivity as neural outcomes. Relative to placebo, losartan modulated the reaction time and arousal differences between social punishment and social reward. On the neural level the losartan-enhanced motivational salience of social rewards was accompanied by stronger ventral striatum-prefrontal connectivity during reward anticipation. Losartan increased the reward-neutral difference in the ventral tegmental area (VTA) and attenuated VTA associated connectivity with the bilateral insula in response to punishment during the outcome phase. Thus, losartan modulated approach-avoidance motivation and emotional salience during social punishment versus social reward via modulating distinct core nodes of the midbrain-striato-frontal circuits. The findings document a modulatory role of the renin-angiotensin system in these circuits and associated social processes, suggesting a promising treatment target to alleviate social dysregulations.SIGNIFICANCE STATEMENT Social deficits and anhedonia characterize several mental disorders and have been linked to the midbrain-striato-frontal circuits of the brain. Based on initial findings from animal models we here combine the pharmacological blockade of the Angiotensin II type 1 receptor (AT1R) via losartan with functional MRI (fMRI) to demonstrate that AT1R blockade enhances the motivational salience of social rewards and attenuates the negative impact of social punishment via modulating the communication in the midbrain-striato-frontal circuits in humans. The findings demonstrate for the first time an important role of the AT1R in social reward processing in humans and render the AT1R as promising novel treatment target for social and motivational deficits in mental disorders.

Association between salivary oxytocin levels and the amygdala and hippocampal volumes

Salivary oxytocin levels have been widely measured and studied in relation to social behavior because of procedural simplicity and noninvasiveness. Although the relationship between oxytocin levels in the blood and the hippocampus and amygdala is now becoming clear with reliable blood oxytocin studies, few studies have examined the relationship between salivary oxytocin and the brain function and structure. This study aimed to investigate whether the salivary oxytocin level is associated with the volume of the amygdala and hippocampus in 178 adults (92 women and 86 men) in their third to seventh decade of life. We performed volumetric analysis of the amygdala and hippocampus using FreeSurfer and measured salivary oxytocin levels using enzyme-linked immunosorbent assay. The results showed contradictory effects of the salivary oxytocin level on the amygdala volume by sex and no significant effect on the hippocampal volume. Specifically, men showed a positive correlation between the salivary oxytocin level and amygdala volume, whereas women showed a negative correlation between the salivary oxytocin level and amygdala volume. The present study's finding of sex differences in the association between salivary oxytocin and brain structure supports previous findings that there are sex differences in the oxytocin system.

Intranasal oxytocin alters attention to emotional facial expressions, particularly for males and those with depressive symptoms

Intranasal oxytocin (OT) can enhance emotion recognition, perhaps by promoting increased attention to social cues. Some studies indicate that individuals with difficulties processing social information, including those with psychopathology, show more pronounced effects in response to OT. As such, there is interest in the potential therapeutic use of OT in populations with deficits in social cognition. The present study examined the effects of intranasal OT on the processing of facial features and selective attention to emotional facial expressions, as well as whether individual differences in depressive symptom severity predict sensitivity to intranasal OT. In a double-blind placebo-controlled within-subject design, eye tracking was used to measure attention to facial features in an emotional expression appraisal task, and attention to emotional expressions in a free-viewing task with a quadrant of multiple faces. OT facilitated the processing of positive cues, enhancing the maintenance of attention to the mouth region of happy faces and to happy faces within a quadrant, with similar effect sizes, despite the latter effect not being statistically significant. Further, persons with depressive symptoms, and particularly males, were sensitive to OT's effects. For males only, OT, relative to placebo, increased attentional focus to the mouth region of all faces. Individuals with depressive symptoms showed less attentional focus on angry (males only) and sad facial expressions, and more attention to happy faces (particularly for males). Results indicate increased sensitivity to OT in males and persons at risk for depression, with OT administration promoting a positive bias in selective attention to social stimuli.

Oxytocinergic Modulation of Stress-Associated Amygdala-Hippocampus Pathways in Humans Is Mediated by Serotonergic Mechanisms

BACKGROUND

The hypothalamic neuropeptide oxytocin (OXT) may exert anxiolytic and stress-reducing actions via modulatory effects on amygdala circuits. Animal models and initial findings in humans suggest that some of these effects are mediated by interactions with other neurotransmitter systems, in particular the serotonin (5-HT) system. Against this background, the present pharmacological resting-state functional magnetic resonance imaging study aimed to determine whether effects of OXT on stress-associated amygdala intrinsic networks are mediated by 5-HT.

METHODS

We employed a randomized, placebo-controlled, double-blind parallel-group, pharmacological functional magnetic resonance imaging resting-state experiment with 4 treatment groups in n = 112 healthy male participants. Participants underwent a transient decrease in 5-HT signaling via acute tryptophan depletion (ATD) or a corresponding placebo-control protocol before the administration of intranasal OXT (24 IU) or placebo intranasal spray.

RESULTS

OXT and 5-HT modulation exerted interactive effects on the coupling of the left amygdala with the ipsilateral hippocampus and adjacent midbrain. OXT increased intrinsic coupling in this pathway, whereas this effect of OXT was significantly attenuated during transiently decreased central serotonergic signaling induced via acute tryptophan depletion. In the absence of OXT or 5-HT modulation, this pathway showed a trend for an association with self-reported stress perception in everyday life. No interactive effects were observed for the right amygdala.

CONCLUSIONS

Together, the findings provide the first evidence, to our knowledge, that the effects of OXT on stress-associated amygdala-hippocampal-midbrain pathways are critically mediated by the 5-HT system in humans.

Oxytocin promotes social proximity and decreases vigilance in groups of African lions

Oxytocin modulates mammalian social behavior; however, behavioral responses to intranasal oxytocin can vary across species and contexts. The complexity of social interactions increases with group dynamics, and the impacts of oxytocin on both within- and between-group contexts are unknown. We tested the effects of intranasal administration of oxytocin on social and non-social behaviors within in-group and out-group contexts in African lions. We hypothesized that, post intranasal oxytocin administration, lions would be in closer proximity with fellow group members, whereas out-group stimuli could either produce a heightened vigilance response or an attenuated one. Compared to control trials, post oxytocin administration, lions increased their time spent in close proximity (reducing their distance to the nearest neighbor) and decreased vigilance toward out-group intruders (reducing their vocalizations following a roar-playback). These results not only have important implications for understanding the evolution of social circuitry but may also have practical applications for conservation efforts.

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We administered oxytocin to groups of African lions

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Relative to control conditions, oxytocin administration enhanced social proximity

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Oxytocin administration decreased vigilance (roars following roar playback)

The Sexual Dimorphic Synapse: From Spine Density to Molecular Composition

A synaptic sexual dimorphism is relevant in the context of multiple neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. Many of these disorders show a different prevalence and progression in woman and man. A similar variance is also present in corresponding animal models. To understand and characterize this dimorphism in pathologies it is important to first understand sex differences in unaffected individuals. Therefore, sexual differences have been studied since 1788, first focusing on brain weight, size, and volume. But as these measures are not directly related to brain function, the investigation of sexual dimorphism also expanded to other organizational levels of the brain. This review is focused on sexual dimorphism at the synaptic level, as these specialized structures are the smallest functional units of the brain, determining cell communication, connectivity, and plasticity. Multiple differences between males and females can be found on the levels of spine density, synaptic morphology, and molecular synapse composition. These differences support the importance of sex-disaggregated data. The specificity of changes to a particular brain region or circuit might support the idea of a mosaic brain, in which each tile individually lies on a continuum from masculinization to feminization. Moreover, synapses can be seen as the smallest tiles of the mosaic determining the classification of larger areas.

Hormonal response to perceived emotional distress in incarcerated men with sexual sadism

Sexual sadists derive pleasure from humiliation, domination and infliction of pain on victims. They display increased penile arousal and activation of brain regions involved in sexual arousal and emotional states when viewing stimuli depicting individuals in physical distress. Neuroactive hormones modulate these regions, but it is unknown if sexual sadists also have endocrine responses to depictions of individuals in distress. The present study examined endocrine responses, elicited by viewing a video depicting an individual in extreme emotional distress, in incarcerated adult male sexual offenders (n = 23) with varying levels of sadistic traits. Sadism, was measured by the Severe Sexual Sadism Scale (SeSaS). Testosterone (T), adrenocorticotropic hormone (ACTH), and oxytocin (OT) were assayed before and after participants watched a video depicting an individual in emotional distress. T responses to the video were significantly and positively associated with SeSaS scores. There were no significant associations between sexual sadism and OT or ACTH. Our findings provide physiological evidence of atypical processing of distress cues in sadism consistent with the role of testosterone in sexual arousal and aggressive behaviors. These findings have implications for the evaluation and treatment of sexual sadists.

A randomized placebo-controlled intranasal oxytocin study on first impressions and reactions to social rejection

Oxytocin is central to pair-bonding in non-human animals. We assessed effects of intranasal oxytocin on bond formation between two opposite-sex strangers. In a double-blind placebo-controlled design, 50 pairs of one man and one woman received oxytocin or placebo spray intranasally. After treatment, they played a social interaction game, followed by tasks designed to measure first impressions of the opposite-sex co-participant, and a virtual ball-tossing game (cyberball), designed to measure reactions to rejection by the co-participant. We found no evidence that intranasal oxytocin can improve first impressions of an opposite-sex stranger, and some Bayesian support against this hypothesis. For rejection sensitivity, we observed a sex-and-context-dependent drug effect on post-ostracism mood ratings, consistent with recent studies indicating that interindividual variation and social context can interact with intranasal oxytocin effects. Further research is needed to determine the generalisability of these findings, i.e. if oxytocin can improve first impressions in humans under different conditions.

Current Understanding of the Involvement of the Insular Cortex in Neuropathic Pain: A Narrative Review

Neuropathic pain is difficult to cure and is often accompanied by emotional and psychological changes. Exploring the mechanisms underlying neuropathic pain will help to identify a better treatment for this condition. The insular cortex is an important information integration center. Numerous imaging studies have documented increased activity of the insular cortex in the presence of neuropathic pain; however, the specific role of this region remains controversial. Early studies suggested that the insular lobe is mainly involved in the processing of the emotional motivation dimension of pain. However, increasing evidence suggests that the role of the insular cortex is more complex and may even be related to the neural plasticity, cognitive evaluation, and psychosocial aspects of neuropathic pain. These effects contribute not only to the development of neuropathic pain, but also to its comorbidity with neuropsychiatric diseases. In this review, we summarize the changes that occur in the insular cortex in the presence of neuropathic pain and analgesia, as well as the molecular mechanisms that may underlie these conditions. We also discuss potential sex-based differences in these processes. Further exploration of the involvement of the insular lobe will contribute to the development of new pharmacotherapy and psychotherapy treatments for neuropathic pain.

Intranasal oxytocin decreases fear generalization in males, but does not modulate discrimination threshold

BACKGROUND

A previously acquired fear response often spreads to perceptually or conceptually close stimuli or contexts. This process, known as fear generalization, facilitates the avoidance of danger, and dysregulations in this process play an important role in anxiety disorders. Oxytocin (OT) has been shown to modulate fear learning, yet effects on fear generalization remain unknown.

METHODS

We employed a randomized, placebo-controlled, double-blind, between-subject design during which healthy male participants received either intranasal OT or placebo (PLC) following fear acquisition and before fear generalization with concomitant acquisition of skin conductance responses (SCRs). Twenty-four to 72 h before the fear learning and immediately after the fear generalization task, participants additionally complete a discrimination threshold task.

RESULTS

Relative to PLC, OT significantly reduced perceived risk and SCRs towards the CS+ and GS1 (the generalization stimulus that is most similar to CS+) during fear generalization, whereas the discrimination threshold was not affected.

CONCLUSIONS

Together, the results suggest that OT can attenuate fear generalization in the absence of effects on discrimination threshold. This study provides the first evidence for effects of OT on fear generalization in humans and suggests that OT may have therapeutic potential in anxiety disorders characterized by dysregulated fear generalization.

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 .

The Effects of Intranasal Oxytocin on Neural and Behavioral Responses to Social Touch in the Form of Massage

Manually-administered massage can potently increase endogenous oxytocin concentrations and neural activity in social cognition and reward regions and intranasal oxytocin can increase the pleasantness of social touch. In the present study, we investigated whether intranasal oxytocin modulates behavioral and neural responses to foot massage applied manually or by machine using a randomized placebo-controlled within-subject pharmaco-fMRI design. 46 male participants underwent blocks of massage of each type where they both received and imagined receiving the massage. Intranasal oxytocin significantly increased subjective pleasantness ratings of the manual but not the machine massage and neural responses in key regions involved in reward (orbitofrontal cortex, dorsal striatum and ventral tegmental area), social cognition (superior temporal sulcus and inferior parietal lobule), emotion and salience (amygdala and anterior cingulate and insula) and default mode networks (medial prefrontal cortex, parahippocampal gyrus, posterior cingulate, and precuneus) as well as a number of sensory and motor processing regions. Both neural and behavioral effects of oxytocin occurred independent of whether subjects thought the massage was applied by a male or female masseur. These findings support the importance of oxytocin for enhancing positive behavioral and neural responses to social touch in the form of manually administered massage and that a combination of intranasal oxytocin and massage may have therapeutic potential in autism.

CLINICAL TRIALS REGISTRATION

The Effects of Oxytocin on Social Touch; registration ID: NCT03278860; URL: https://clinicaltrials.gov/ct2/show/NCT03278860.

Oxytocin Prevents the Development of 3-NP-Induced Anxiety and Depression in Male and Female Rats: Possible Interaction of OXTR and mGluR2

Huntington disease (HD) is a progressive neurological disorder with dominant motor symptoms. It also has psychiatric manifestations, like anxiety and depression, that can emerge themselves before motor symptoms and impose a major burden on patients. Oxytocin (OXT) is a newly emerged treatment for disorders like autism and schizophrenia and recently is using to alleviate depression and anxiety. In the current study, we investigated the behavioral and molecular effects of OXT on the development of anxiety and depression in 3-nitropropionic acid (3-NP)-induced model of HD. Anxiety- and depression-like behaviors as well as the levels of oxytocin receptor (OXTR), metabotropic glutamate receptor (mGluR) 2, mGluR5, and glutathione (GSH) were measured in striatum, hippocampus, prefrontal cortex, and amygdala. Also, we questioned if sex had any modulatory effect. We found that 3-NP increased anxiety and depression compared to controls. It also reduced the levels of OXTR and mGluR2, increased mGluR5, and reduced GSH in studied brain regions. Pretreatment with OXT before the injection of 3-NP ameliorated anxiety and depression. Additionally, it protected the brain from developing low levels of OXTR, mGluR2, and GSH and high levels of mGluR5 in studied regions. The protective effects of OXT were similar between male and female animals. These data suggest that OXTR, mGluR2, mGluR5, and GSH may contribute to psychiatric manifestations of HD. In addition, pretreatment with OXT could prevent the mood changes in male and female rats.

Imaging the "social brain" in schizophrenia: A systematic review of neuroimaging studies of social reward and punishment

Decreased social functioning and high levels of loneliness and social isolation are common in schizophrenia spectrum disorders (SSD), contributing to reduced quality of life. One key contributor to social impairment is low social motivation, which may stem from aberrant neural processing of socially rewarding or punishing stimuli. To summarize research on the neurobiology of social motivation in SSD, we performed a systematic literature review of neuroimaging studies involving the presentation of social stimuli intended to elicit feelings of reward and/or punishment. Across 11 studies meeting criteria, people with SSD demonstrated weaker modulation of brain activity in regions within a proposed social interaction network, including prefrontal, cingulate, and striatal regions, as well as the amygdala and insula. Firm conclusions regarding neural differences in SSD in these regions, as well as connections within networks, are limited due to conceptual and methodological inconsistencies across the available studies. We conclude by making recommendations for the study of social reward and punishment processing in SSD in future research.

Acute effects of oxytocin in music performance anxiety: a crossover, randomized, placebo-controlled trial

RATIONALE

Individuals with music performance anxiety (MPA) present physical, behavioral, and cognitive manifestations of anxiety, in addition to information processing deficits, especially in facial emotion recognition (FER).

OBJECTIVES

To assess the effects of a single dose of intranasal oxytocin (24 IU) on FER in a sample of musicians with high and low MPA (primary outcome), as well as indicators of mood/anxiety and self-assessed performance (secondary outcomes).

METHODS

Crossover, randomized, double-blind, placebo-controlled trial involving 43 male musicians with different levels of MPA. Participants completed a static facial emotion recognition task and self-rated mood and performance scales. Data were analyzed using ANOVA 2 × 0 for crossover trials and the Omnibus test (measure of separability between intervention and carryover effects).

RESULTS

Only musicians with high MPA treated with oxytocin had a higher accuracy in the recognition of happiness (p < 0.03; d > 0.72). No effects of oxytocin were found on mood indicators or on self-perceived performance, regardless of MPA level.

CONCLUSIONS

The results indicate possible benefits of the acute treatment with oxytocin in MPA, which may improve the management of this common and disabling condition that affects professional musicians. The appropriate perception of positive feedback may increase confidence and feelings of social acceptance, reducing symptoms associated with the condition. The lack of effects on mood/anxiety and cognition may be explained by the context-dependent characteristic of the effects of oxytocin, since the experiment did not represent an actual situation of social threat.

TRIAL REGISTRATION

Brazilian Clinical Trials Registry (Registro Brasileiro de Ensaios Clínicos): No. RBR-9cph2q.

Potential for limited reinforcing and abuse-related subjective effects of intranasal oxytocin

BACKGROUND

There has been growing interest in using oxytocin as a pharmacotherapy for psychiatric disorders, including substance use disorder. Limited data exist regarding oxytocin's reinforcing efficacy, which is a necessary consideration for novel pharmacotherapies, especially in substance-using populations.

AIMS

This study aimed to determine the potential reinforcing effects of intranasally administered oxytocin by assessing behavioral economic demand and subjective effects.

METHODS

Healthy adults (n = 23) participated in a double-blind, repeated-measures, laboratory study wherein they received intranasal oxytocin (40 IU) or placebo in a randomized order across two sessions. Participants completed drug purchasing tasks at the conclusion of both sessions. Throughout both sessions, subjective and physiological effects were assessed.

RESULTS

Demand-curve analysis of purchasing tasks revealed greater median purchasing for oxytocin relative to placebo. Physiological and subjective effects did not significantly differ between oxytocin and placebo. However, a nonsignificant trend was observed for moderately greater drug liking for oxytocin relative to placebo. There was a significant, positive correlation between the difference in drug liking (between oxytocin and placebo) and the difference in lowest-price purchasing (between oxytocin and placebo).

CONCLUSIONS

These data suggest the potential for limited reinforcing and abuse-related subjective effects of intranasal oxytocin. Given the small sample, the greater drug liking of oxytocin compared to placebo, and the positive relation between demand and drug liking, it is possible that oxytocin may produce reinforcing effects in some participants. Therefore, additional studies of oxytocin reinforcement are warranted.

Modulation of the Endocannabinoid and Oxytocinergic Systems as a Potential Treatment Approach for Social Anxiety Disorder

Social anxiety disorder (SAD), or social phobia, is one of the most common types of anxiety disorder, with a lifetime prevalence that can reach 15%. Pharmacological treatments for SAD have moderate efficacy and are associated with significant adverse reactions. Therefore, recent studies have focused on searching for new treatments for this disorder. Preclinical studies and preliminary evidence in humans suggest that the phytocannabinoid cannabidiol and the neuropeptide oxytocin have anxiolytic effects. In the present text, we review this evidence and its implications for pharmacological treatment. We conclude that although current available studies show promising results regarding both the safety and efficacy of cannabidiol and oxytocin for the treatment of SAD, most studies were performed using single or few doses of these compounds, with small sample sizes. Therefore, future studies should explore the anxiolytic potential of these compounds using long-term, placebo-controlled designs with larger samples to elucidate the possible use of these compounds in the treatment of SAD.

Oxytocin modulates the temporal dynamics of resting EEG networks

Oxytocin is a key modulator of social interaction, but we possess little knowledge of its underlying effects on neuropsychological processes. We used a spatio-temporal EEG microstates analysis to reveal oxytocin's effects on the temporal dynamics of intrinsically generated activity in neural networks. Given oxytocin's known anxiolytic effects, we hypothesized that it increases the temporal stability of the four archetypal EEG resting networks. Eighty-six male participants had received oxytocin or placebo intranasally before we recorded their resting EEG. As hypothesized, oxytocin globally increased the average duration of the four archetypal resting networks and specifically decreased the occurrence and coverage of an autonomic processing-related network to benefit greater coverage of an attention-related network. Moreover, these neurophysiological changes were more pronounced in participants with high anxiety levels and strong subjectively experienced effects of the oxytocin administration. In sum, our study shows that oxytocin reduces rapid switching among neural resting networks by increasing their temporal stability. Specifically, it seems to reduce the brain's need for preparing the internally-oriented processing of autonomic information, thus enabling the externally-oriented processing of social information. Changes in the temporal dynamics of resting networks might underlie oxytocin's anxiolytic effects - potentially informing innovative psychobiological treatment strategies.

How Consistent Contributors Inspire Individuals to Cooperate: The Role of Moral Elevation and Social Value Orientation

Achieving cooperation to address social dilemmas has long been a global problem. This study examined, using an environment-focused step-level public-goods-dilemma game, the effect a consistent contributor (CC) has on group cooperation, as well as the mediating role moral elevation and the moderating role social value orientation (SVO) play in this process. A total of 196 students were recruited and classified as “pro-selfs” or “pro-socials” based on their SVOs; individuals with the same SVO characterization were randomly allocated to groups of four, and then randomly assigned to the CC condition or the control condition to play 15 rounds of public-goods-dilemma games. In the CC condition, additional computer-controlled players represented the CCs. The results showed that the CC groups cooperated and earned more than the control groups did. Multi-level mediation analysis confirmed that moral elevation partially mediates the CC effect. Although the CCs had a direct impact on both pro-socials and pro-selfs, multi-level moderated-mediation analysis demonstrated that CCs influenced pro-socials directly, but affected pro-selfs’ decision-making indirectly, through moral elevation. This study contributes to a better understanding of sustainability of cooperation in social dilemmas by showing that consistent cooperative behaviors are contagious, and that their effects differ based on an individuals’ SVO.

Oxytocin Facilitates Empathic- and Self-embarrassment Ratings by Attenuating Amygdala and Anterior Insula Responses

The hypothalamic neuropeptide oxytocin has been reported to enhance emotional empathy in association with reduced amygdala activation, although to date studies have not investigated empathy for individuals expressing self-conscious, moral emotions which engage mentalizing as well as emotion processing networks. In the current randomized, double-blind placebo controlled functional MRI experiment in 70 male and female subjects we have therefore investigated the effects of intranasal oxytocin (40 IU) on behavioral and neural responses to embarrassment experienced by others or by self. Results showed that oxytocin significantly increased ratings of both empathic and self-embarrassment and concomitantly decreased skin conductance response, activation in the right amygdala and insula but not in the medial prefrontal cortex. The amygdala effects of oxytocin were associated with the magnitude of the skin conductance response and trait anxiety scores. Overall our results demonstrate that oxytocin increases ratings of self- and other embarrassment and that this is associated with reduced physiological arousal and activity in neural circuits involved in emotional arousal. The neural effects of oxytocin were more pronounced stronger in individuals with high trait anxiety suggesting that it may particularly reduce their anxiety in embarrassing situations.