Sex-specific effects of intranasal oxytocin on autonomic nervous system and emotional responses to couple conflict

Modulation of strategic status signaling: oxytocin changes men's fluctuations of status products preferences in their female partners' menstrual cycle

RATIONALE

Women exhibit subtle fluctuations in mating-related behaviors throughout their menstrual cycle, and men are capable of detecting these ovulatory cues. This ability may impact male mating behavior, prompting adjustments in their preferences for consumer products based on these signals. Nonetheless, the potential influence of oxytocin on men's preferences for status products, particularly in the context of their female partners' menstrual cycles, is not yet known.

OBJECTIVES

This study aims to explore how oxytocin regulates men's responses to their female partners' ovulation in heterosexual romantic relationships by specifically examining changes in their preferences for status consumption.

METHODS

Through a pilot study (N = 110) and two main studies (N1 = 789, N2 = 120), we analyzed how oxytocin influences fluctuations in men's preferences for status products throughout their female partners' menstrual cycles. In Study 1, we examined the impact of the female menstrual cycle on men's preferences for status products. In Study 2, we employed intranasal oxytocin to investigate its modulatory effect on the menstrual cycle's influence.

RESULTS

Findings revealed that men demonstrated a lower preference for status products during their partners' ovulation compared to non-ovulatory phases. Furthermore, intranasal oxytocin significantly reduced men's liking for status products during the ovulatory phase, but not during the menstrual phase, with a stronger effect observed among men with a heightened intuitive inclination.

CONCLUSIONS

These results suggest that men in committed relationships strategically adapt their consumption of status products according to their female partners' menstrual cycles, with oxytocin playing a moderating role in this adaptation and individual differences influencing responses.

Oxytocin does not impact forced-choice recognition memory in an experimental trauma film paradigm with healthy women

Introduction

Traumatic experiences are thought to alter memory acquisition and consolidation. Cognitive models of PTSD suggest that voluntary and involuntary memories after trauma can be independently addressed through interventions. The administration of oxytocin before exposure to a trauma film led to more intrusive (involuntary) memories than placebo. The effect of oxytocin on voluntary memory of the traumatic film, however, remains unclear. The current study aimed to assess whether intranasal oxytocin administration facilitates forced-choice recognition memory after a trauma film paradigm.

Material & methods

We performed a pooled analysis of two randomized, double-blind, placebo-controlled studies (N = 437) to assess the impact of intranasal oxytocin administration on declarative memory. Participants received 24 I.U. of oxytocin, either 40 minutes before a trauma film paradigm or immediately afterward. We applied a forced-choice recognition task seven days after the trauma film paradigm. The task comprised pre-, peri, and post-trauma film scene details.

Results

The administration of oxytocin did not affect recognition performance for any film scene (F(2, 401) = .49, p = .61). Participants remembered significantly more peri-traumatic film details compared to pre- and post-trauma details (F(1.72, 802) = 103.38, p <.001).

Discussion

Although the exogenous oxytocin administration before a trauma film has been shown to influence the acquisition of intrusive memories, it does not seem to affect the recognition memory of trauma film details. That aligns with cognitive models of PTSD, suggesting that voluntary and involuntary memory after trauma can be independently addressed through experimental interventions.

Effects of intranasal oxytocin on fear extinction learning

Once a threat no longer exists, extinction of conditioned fear becomes adaptive in order to reduce allotted resources towards cues that no longer predict the threat. In anxiety and stress disorders, fear extinction learning may be affected. Animal findings suggest that the administration of oxytocin (OT) modulates extinction learning in a timepoint-dependent manner, facilitating extinction when administered prior to fear conditioning, but impairing it when administered prior to extinction learning. The aim of the present study was to examine if these findings translate into human research. Using a randomized, double-blind, placebo-controlled, 2-day fear conditioning and extinction learning design, behavioral (self-reported anxiety), physiological (skin conductance response), neuronal (task-based and resting-state functional magnetic resonance imaging), and hormonal (cortisol) data were collected from 124 naturally cycling (taking no hormonal contraceptives) healthy females. When administered prior to conditioning (Day 1), OT, similar to rodent findings, did not affect fear conditioning, but modulated the intrinsic functional connectivity of the anterior insula immediately after fear conditioning. In contrast to animal findings, OT impaired, not facilitated, extinction learning on the next day and increased anterior insula activity. When administered prior to extinction learning (day 2), OT increased the activity in the bilateral middle temporal gyrus, and similar to animal findings, reduced extinction learning. The current findings suggest that intranasal OT impedes fear extinction learning in humans regardless of the timepoint of administration, providing new insights and directions for future translational research and clinical applications.

Sex differences in response to intranasal oxytocin as an adjunctive therapy for patients with severe mental illness

Studies investigating the potential benefits of intranasal oxytocin (INOT) as an add-on treatment for patients with severe mental illness (SMI) have yielded inconsistent results, potentially due to sex differences in response to INOT. This study explored the differential effects of INOT among male and female patients with SMI. A secondary analysis was conducted on a previously studied group of patients who participated in a double-blind, placebo-controlled trial evaluating the impact of INOT as an add-on treatment for patients with SMI. Patients treated in inpatient settings (N = 87) received twice-daily INOT (32IU) or placebo (PLC) for a period of four weeks. Sex moderated the effect of OT/PLC on the Hamilton Rating Scale for Depression (HRDS) (p < 0.001). A significant effect for sex was found in the Hopkins Symptom Checklist-short form (HSCL-11) (p = 0.04) and HRDS (p < 0.001), with females showing greater reductions in anxiety and depression symptoms and severity. This effect was not found for males. We conclude that the addition of INOT to the treatment of patients with SMI in an inpatient setting was beneficial for female patients, particularly reducing depressive symptoms, but not for male patients. Future studies should aim to identify patients who are more likely to benefit from INOT administration.

Neuroimaging and behavioral evidence of sex-specific effects of oxytocin on human sociality

Although the social role of oxytocin came to light due to sex-specific interactions such as mother-offspring bonding, current understanding of sex differences in the effects of oxytocin on human sociality is limited because of the predominance of all-male samples. With the increasing inclusion of females in intranasal oxytocin research, it is now possible to explore such patterns. Neuroimaging studies reveal relatively consistent sex-differential effects of oxytocin on the activation of brain regions associated with processing social stimuli - particularly the amygdala. Findings from behavioral research are varied but suggest that oxytocin more often facilitates social cognition and positive social interactions in males, with context-dependent effects in each sex. We discuss potential biological and psychological mechanisms underlying the reported sex differences, and conclude with considerations for future research and clinical applications of oxytocin.

A narrative review of mechanisms linking romantic relationship experiences to sleep quality

Although a significant body of research has revealed associations between romantic relationship experiences and sleep quality, there has not been clarity regarding the mechanisms underlying such associations. Toward this end, we review the existing studies that have tested mechanisms linking romantic relationship experiences to sleep quality. Guided by both theory and existing research, we organize our review around five key categories of mechanisms that may explain associations between romantic relationship experiences and sleep quality: emotional/affective responses, self-perceptions, social perceptions, self-regulation, and biological functioning. Our review of the literature indicates strong evidence in support of the mediating effects of emotional/affective mechanisms (e.g. emotions and mood states) in explaining associations between various aspects of romantic relationships (e.g. relationship satisfaction, partner conflicts, and attachment orientation) and sleep quality. Although there is ample theoretical support for the other mechanisms proposed, and although all proposed mechanisms have been separately linked to both romantic relationship experiences and sleep quality, few studies have directly tested them, pointing to profitable directions for future research. Understanding underlying mechanisms will enable the development of wise, process-based interventions that target specific mechanisms to improve couple members' sleep quality and romantic relationship functioning.

Ground-based adaptive horsemanship lessons for veterans with post-traumatic stress disorder: a randomized controlled pilot study

Introduction

Equine-assisted services (EAS) has received attention as a potential treatment strategy for post-traumatic stress disorder (PTSD), as existing literature indicates that symptoms may decrease following EAS. Relatively little is known about the mechanisms at play during lessons and if physiological measures are impacted. The objectives of this pilot study were to 1) explore the effects of adaptive horsemanship (AH) lessons on symptoms of PTSD, hormone concentrations, and social motor synchrony; 2) determine if physiological changes occur as veterans interact with horses; and 3) explore if the interaction between veteran and horse changes over the 8-week session.

Methods

Veterans with PTSD were randomly assigned to control (CON, n = 3) or AH (n = 6) groups for an 8-week period (clinical trial; NCT04850573; clinicaltrials.gov). Veterans completed the PTSD Checklist (PCL-5) and Brief Symptom Inventory (BSI) at pre-, post-, and 2- and 6-month follow-up time points. They also completed a social motor synchrony test (pendulum swinging) and blood draw at pre- and post-time points. In weeks 1, 4, and 8, blood samples were drawn at 0 min, 3 min, 5 min, 25 min, and 30 min during the 30-min AH lessons. Veterans completed the Human-Animal Interaction Scale (HAIS) after each lesson. Blood samples were assayed for plasma cortisol, epinephrine, norepinephrine, and oxytocin. Data were analyzed with repeated measure ANOVAs. Changes in PTSD symptoms from pre- to post-time point were analyzed with paired t-tests.

Results

Changes in PCL-5 scores tended to differ (p = 0.0989), and global BSI scores differed (p = 0.0266) between AH (-11.5 ± 5.5, mean ± SE; -0.5 ± 0.2) and CON (5.3 ± 5.4; 0.4 ± 0.2) groups. Social motor synchrony and hormone concentrations did not differ between groups or time points (p > 0.05). Cortisol, norepinephrine, and oxytocin concentrations did not differ across sessions (p > 0.05). Epinephrine concentrations tended (p = 0.0744) to decrease from week 1 to 4 of sessions. HAIS scores increased (p ≥ 0.0437) in week 3 and remained elevated as compared to week 1.

Discussion

Participant recruitment was the greatest challenge. These preliminary results agree with the literature suggesting that EAS can reduce symptoms of PTSD.

Effects of oral contraceptives on intrusive memories: a secondary analysis of two studies using the trauma film paradigm in healthy women

Background: Women are more likely to develop post-traumatic stress disorder (PTSD) than men. Recent research suggests an impact of oral contraceptive (OC) intake on PTSD and intrusive memories, a hallmark symptom of PTSD. Although a majority of women use OCs at some point in their lives, the effects on PTSD pathogenesis are only poorly understood.Objective: In the current paper, we aimed to investigate the impact of OC intake on the acquisition and consolidation of intrusive memories in healthy women after watching a trauma film paradigm.Methods: We performed a secondary analysis of a pooled dataset (N = 437) of two previously conducted and published studies investigating the effect of oxytocin on the development of intrusive memories.Results: Women taking OCs showed an attenuated decline of intrusive memories over time after having watched the trauma film compared to naturally cycling women (F(2.75, 1167) = 3.79, p = .03, η p 2  = .01).Conclusion: These findings indicate that the intake of OCs is associated with the development of intrusive memories after a trauma film paradigm. This indication emphasizes the need to further investigate the complex impact of OCs and gonadal hormones on fear learning processes and PTSD.

Effects of exogenous oxytocin and estradiol on resting-state functional connectivity in women and men

Possible interactions of the neuropeptide oxytocin and the sex hormone estradiol may contribute to previously observed sex-specific effects of oxytocin on resting-state functional connectivity (rsFC) of the amygdala and hippocampus. Therefore, we used a placebo-controlled, randomized, parallel-group functional magnetic resonance imaging study design and measured amygdala and hippocampus rsFC in healthy men (n = 116) and free-cycling women (n = 111), who received estradiol gel (2 mg) or placebo before the intranasal administration of oxytocin (24 IU) or placebo. Our results reveal significant interaction effects of sex and treatments on rsFC of the amygdala and hippocampus in a seed-to-voxel analysis. In men, both oxytocin and estradiol significantly decreased rsFC between the left amygdala and the right and left lingual gyrus, the right calcarine fissure, and the right superior parietal gyrus compared to placebo, while the combined treatment produced a significant increase in rsFC. In women, the single treatments significantly increased the rsFC between the right hippocampus and the left anterior cingulate gyrus, whereas the combined treatment had the opposite effect. Collectively, our study indicates that exogenous oxytocin and estradiol have different region-specific effects on rsFC in women and men and that the combined treatment may produce antagonistic effects.

Oxytocin vs. placebo effects on intrusive memory consolidation using a trauma film paradigm: a randomized, controlled experimental study in healthy women

Oxytocin administration during a trauma analogue has been shown to increase intrusive memories, which are a core symptom of post-traumatic stress disorder (PTSD). However, it is unknown whether oxytocin influences the acquisition or the consolidation of the trauma. The current study investigates the effect of the activation of the oxytocin system during the consolidation of an analogue trauma on the formation of intrusive memories over four consecutive days and whether this effect is influenced by individual neurobiological, genetic, or psychological factors. We conducted a randomized double-blind placebo-controlled study in 217 healthy women. They received either a single dose of intranasal oxytocin (24 IU) or placebo after exposure to a trauma film paradigm, which reliably induces intrusive memories. We used a general random forest to examine a potential heterogeneous treatment effect of oxytocin on the consolidation of intrusive memories. Furthermore, we used a poisson regression to examine whether salivary alpha amylase activity (sAA) as a marker of noradrenergic activity and cortisol response to the film, polygenic risk score (PRS) for psychiatric disorders, and psychological factors influence the number of intrusive memories. We found no significant effect of oxytocin on the formation of intrusive memories (F(2, 543.16) = 0.75, p = 0.51, ηp2 = 0.00) and identified no heterogeneous treatment effect. We replicated previous associations of the PRS for PTSD, sAA and the cortisol response on intrusive memories. We further found a positive association between high trait anxiety and intrusive memories, and a negative association between the emotion regulation strategy reappraisal and intrusive memories. Data of the present study suggest that the consolidation of intrusive memories in women is modulated by genetic, neurobiological and psychological factors, but is not influenced by oxytocin. Trial registration: NCT03875391.

Effects of intranasal oxytocin and positive couple interaction on immune factors in skin wounds

BACKGROUND

Intimate social relationships improve individual health and longevity, an effect which is supposed to be mediated through stress-sensitive endocrine and immune mechanisms in response to positive interaction behavior. On a neuroendocrine level, oxytocin (OT) buffers stress responses, modulates social attachment behavior and has been associated with cytokine expression. Consequently, the aim of the present study was to investigate instructed positive couple interaction, observed behavior, and OT in their effect on immune function.

METHODS

In a 4-group design, 80 healthy couples (N = 160 individuals) received four standard dermal suction blister wounds and were randomized to instructed positive interaction/control and intranasal OT/placebo. Unstimulated cytokines (IL-1β, IL-6, TNF-α) were assessed from wound liquid at 40 min, 105 min and 24 hrs after wounding.

RESULTS

Overall, group assignment did not affect friendly or dominant behavior during the interaction sequence. IL-1β and IL-6 levels, however, were moderated by group assignment with lowest levels in women in the positive interaction and OT condition in IL-1 and highest levels in IL-6. TNF-α responses to wounding were not affected from group assignment, however observed friendliness in women was associated with lower TNF-α levels.

DISCUSSION

These findings support the immune-regulating role of friendly behavior in romantic couples. Above this, the data provide the first empirical evidence that an intervention that simultaneously targets neuroendocrine mediators and behavior could affect immune function in a sex specific manner and with potential long-term health relevance.

Exogenous estradiol and oxytocin modulate sex differences in hippocampal reactivity during the encoding of episodic memories

Considerable evidence supports sex differences in episodic memory. The hormones estradiol and oxytocin both affect episodic memory and may contribute to these sex differences, but possible underlying hormonal interactions have not been tested in a sample involving both sexes. To this end, we conducted a randomized, placebo-controlled, parallel-group functional magnetic resonance imaging (fMRI) study including healthy free-cycling women (n = 111) and men (n = 115). The fMRI session was conducted under four experimental conditions: 1. transdermal estradiol (2 mg) and intranasal oxytocin (24 IU), 2. transdermal placebo and intranasal oxytocin, 3. transdermal estradiol and intranasal placebo, 4. transdermal placebo and intranasal placebo. Participants were scanned during the encoding of positive, neutral, and negative scenes. Recognition memory was tested three days following the scanning sessions without additional treatments. Under placebo, women showed a significantly better recognition memory and increased hippocampal responses to subsequently remembered items independent of the emotional valence compared to men. The separate treatments with either hormone significantly diminished this mnemonic sex difference and reversed the hippocampal activation pattern. However, the combined treatments produced no significant effect. Collectively, the results suggest that both hormones play a crucial role in modulating sex differences in episodic memory. Furthermore, possible antagonistic interactions between estradiol and oxytocin could explain previously observed opposing hormonal effects in women and men.

The Effect of Intranasal Oxytocin on the Association Between Couple Interaction and Sleep: A Placebo-Controlled Study

OBJECTIVE

Although most people in romantic relationships cosleep, biosocial modulators of sleep quality have only recently come into focus. Oxytocin (OT) might be one such modulator, as it had been shown to increase social attachment and safety. We investigated the association between everyday life couple interaction and sleep quality, as well as the effects of OT on this association.

METHODS

Eighty heterosexual couples ( N = 160 individuals, mean [standard deviation] age = 28 [5] years) were randomized to self-administer a) 32 international units of intranasal OT or b) placebo during 5 consecutive days. Each morning, they reported on sleep quality, and on subjective feelings of closeness and valence of couple interaction at a maximum of four times a day. Data were analyzed using hierarchical linear models.

RESULTS

Subjective closeness ( B = 0.43, t (73) = 3.80, p < .001) and valence (negative - positive) of couple interaction ( B = 0.50, t (73) = 3.91, p < .001) were positively associated with sleep quality. Persons with OT reported higher levels of sleep quality than those without ( B = 0.47, t (74) = 2.32, p = .023). The association between closeness and sleep quality was stronger with OT than without (OT by closeness: B = 0.31, t (72) = 2.29, p = .025; OT by valence of interaction: B = 0.27, t (72) = 1.77, p = .081). Whereas the effect of couple interaction on sleep quality was strong in men, the OT effects were especially pronounced in women.

CONCLUSIONS

Our results suggest that enhancing closeness and positive couple interaction in cosleeping partners might be a way to improve sleep quality. The moderating effects of OT and sex on the association between couple interaction and sleep quality can have important implications for sleep therapy.Trial Registration: The study was preregistered at ClinicalTrials.gov ("Oxytocin, Couple Interaction, and Wound Healing" study, identifier NCT01594775). The present analyses were not preregistered.

Effects of Chronic and Acute Intranasal Oxytocin Treatments on Temporary Social Separation in Adult Titi Monkeys (Plecturocebus cupreus)

In socially monogamous titi monkeys, involuntary separation from a pair mate can produce behavioral distress and increased cortisol production. The neuropeptide oxytocin (OXT) is thought to play an important role in the separation response of pair-bonded species. Previous studies from our lab have shown that chronic intranasal oxytocin (IN OXT) during development can have long-term effects on adult social behavior. In the current study, we examined the chronic and acute effects of IN OXT or Saline (SAL) on the subjects’ response to a brief separation from their pair mates. Subjects with a history of chronic IN OXT or SAL treatment during development received a single dose of OXT or SAL as adults 30 min before being separated from their pair mate. Chronic treatment consisted of a daily dose of IN OXT (0.8 IU/kg) or SAL (control) from 12 to 18 months of age. Subjects (N = 29) were introduced to a pair mate at 30 months of age. After the pairs had cohabitated for 5 months, pairs underwent two “Brief Separation” (OXT and SAL) and two “Non-Separation” (OXT and SAL) test sessions. Vocalizations and locomotion were measured as behavioral indices of agitation or distress during the Brief Separation and Non-Separation periods (30 min each). We collected blood samples after the Brief Separation and Non-Separation periods to measure cortisol levels. Our results showed subjects treated with chronic OXT had a reduction in long call and peep vocalizations compared to subjects treated with chronic SAL. Subjects treated with chronic SAL and acute OXT produced more peeps and long calls compared to animals treated with acute SAL; however, patterns in this response depended on sex. Cortisol and locomotion were significantly higher during the Brief Separation period compared to the Non-Separation period; however, we did not find any treatment or sex effects. We conclude that chronic IN OXT given during development blunts the separation response, while acute OXT in chronic SAL subjects had sexually dimorphic effects, which could reflect increased partner seeking behaviors in males and increased anxiety in females.

Intranasal oxytocin administration impacts the acquisition and consolidation of trauma-associated memories: a double-blind randomized placebo-controlled experimental study in healthy women

Intrusive memories are a hallmark symptom of post-traumatic stress disorder (PTSD) and oxytocin has been implicated in the formation of intrusive memories. This study investigates how oxytocin influences the acquisition and consolidation of trauma-associated memories and whether these effects are influenced by individual neurobiological and genetic differences. In this randomized, double-blind, placebo-controlled study, 220 healthy women received either a single dose of intranasal 24IU oxytocin or a placebo before exposure to a trauma film paradigm that solicits intrusive memories. We used a "general random forest" machine learning approach to examine whether differences in the noradrenergic and hypothalamic-pituitary-adrenal axis activity, polygenic risk for psychiatric disorders, and genetic polymorphism of the oxytocin receptor influence the effect of oxytocin on the acquisition and consolidation of intrusive memories. Oxytocin induced significantly more intrusive memories than placebo did (t(188.33) = 2.12, p = 0.035, Cohen's d = 0.30, 95% CI 0.16-0.44). As hypothesized, we found that the effect of oxytocin on intrusive memories was influenced by biological covariates, such as salivary cortisol, heart rate variability, and PTSD polygenic risk scores. The five factors that were most relevant to the oxytocin effect on intrusive memories were included in a Poisson regression, which showed that, besides oxytocin administration, higher polygenic loadings for PTSD and major depressive disorder were directly associated with a higher number of reported intrusions after exposure to the trauma film stressor. These results suggest that intranasal oxytocin amplifies the acquisition and consolidation of intrusive memories and that this effect is modulated by neurobiological and genetic factors. Trial registration: NCT03031405.

Facial threat affects trust more strongly than facial attractiveness in women than it does in men

Trust is essential in initiating social relationships. Due to the differential evolution of sex hormones as well as the fitness burdens of producing offspring, evaluations of a potential mating partner's trustworthiness likely differ across sexes. Here, we explore unknown sex-specific effects of facial attractiveness and threat on trusting other-sex individuals. Ninety-three participants (singles; 46 women) attracted by the other sex performed an incentivized trust game. They had to decide whether to trust individuals of the other sex represented by a priori-created face stimuli gradually varying in the intensities of both attractiveness and threat. Male and female participants trusted attractive and unthreatening-looking individuals more often. However, whereas male participants' trust behavior was affected equally by attractiveness and threat, female participants' trust behavior was more strongly affected by threat than by attractiveness. This indicates that a partner's high facial attractiveness might compensate for high facial threat in male but not female participants. Our findings suggest that men and women prioritize attractiveness and threat differentially, with women paying relatively more attention to threat cues inversely signaling parental investment than to attractiveness cues signaling reproductive fitness. This difference might be attributable to an evolutionary, biologically sex-specific decision regarding parental investment and reproduction behavior.

Intranasal oxytocin administration but not peripheral oxytocin regulates behaviors of attachment insecurity: A meta-analysis

In light of the roles of oxytocin (OT) in social bonding and interpersonal relationship, studies have examined the roles of OT in human attachment, but by and large previous findings are inconsistent. Here, we conducted - meta-analyses to estimate the associations between peripheral OT level (e.g., blood and salivary OT) and attachment (i.e., attachment dimensions and behaviors of attachment insecurity) and examine the effects of intranasal OT administration on behaviors of attachment insecurity. The analyses indicated that: (1) Peripheral OT level was not significantly associated with attachment dimensions (e.g., attachment anxiety and attachment avoidance) and behaviors of attachment insecurity; (2) intranasal OT administration significantly reduced behaviors of attachment insecurity of neutral contexts, particularly behaviors of attachment avoidance. The findings suggest that intranasal OT administration is an available approach for reducing behaviors of attachment insecurity of interpersonal situations with ambiguous social cues, which implicates suggestions for therapeutic treatments of attachment-related dysfunctions.

Sex Differences in the Hypothalamic Oxytocin Pathway to Locus Coeruleus and Augmented Attention with Chemogenetic Activation of Hypothalamic Oxytocin Neurons

The tightly localized noradrenergic neurons (NA) in the locus coeruleus (LC) are well recognized as essential for focused arousal and novelty-oriented responses, while many children with autism spectrum disorder (ASD) exhibit diminished attention, engagement and orienting to exogenous stimuli. This has led to the hypothesis that atypical LC activity may be involved in ASD. Oxytocin (OXT) neurons and receptors are known to play an important role in social behavior, pair bonding and cognitive processes and are under investigation as a potential treatment for ASD. However, little is known about the neurotransmission from hypothalamic paraventricular (PVN) OXT neurons to LC NA neurons. In this study, we test, in male and female rats, whether PVN OXT neurons excite LC neurons, whether oxytocin is released and involved in this neurotransmission, and whether activation of PVN OXT neurons alters novel object recognition. Using "oxytocin sniffer cells" (CHO cells that express the human oxytocin receptor and a Ca indicator) we show that there is release of OXT from hypothalamic PVN OXT fibers in the LC. Optogenetic excitation of PVN OXT fibers excites LC NA neurons by co-release of OXT and glutamate, and this neurotransmission is greater in males than females. In male, but not in female animals, chemogenetic activation of PVN OXT neurons increases attention to novel objects.

Sex-specific associations of basal steroid hormones and neuropeptides with Conduct Disorder and neuroendocrine mediation of environmental risk

Conduct Disorder (CD) is characterized by severe aggressive and antisocial behavior. The stress hormone system has frequently been investigated as a neurobiological correlate of CD, while other interacting neuroendocrine biomarkers of sex hormone or neuropeptide systems have rarely been studied, especially in females. We examined multiple basal neuroendocrine biomarkers in female and male adolescents with CD compared to healthy controls (HCs), and explored whether they mediate effects of environmental risk factors on CD. Within the FemNAT-CD study, salivary cortisol, alpha-amylase, testosterone, dehydroepiandrosterone-sulfate (DHEA-S), estradiol, progesterone, oxytocin, and arginine-vasopressin were measured under basal conditions in 166 pubertal adolescents with CD, and 194 sex-, age-, and puberty-matched HCs (60% females, 9-18 years). Further, environmental risk factors were assessed. Single hormone analyses showed higher DHEA-S, and lower estradiol and progesterone levels in both females and males with CD relative to HCs. When accounting for interactions between neuroendocrine systems, a male-specific sex hormone factor (testosterone/DHEA-S) predicted male CD, while estradiol and a stress-system factor (cortisol/alpha-amylase) interacting with oxytocin predicted female CD. Estradiol, progesterone, and oxytocin partly explained associations between early environmental risk and CD. Findings provide evidence for sex-specific associations between basal neuroendocrine measures and CD. Especially altered sex hormones (androgen increases in males, estrogen reductions in females) robustly related to CD, while basal stress-system measures did not. Early environmental risk factors for CD may act partly through their effects on the neuroendocrine system, especially in females. Limitations (e.g., basal neuroendocrine assessment, different sample sizes per sex, pubertal participants, exploratory mediation analyses) are discussed.

Oxytocin and social anxiety: Interactions with sex hormones

Oxytocin has been associated with anxiolytic and stress reducing effects in a number of studies. Less is known about the associations of endogenous oxytocin concentrations and their interaction with other hormones such as sex hormones in relation to self-reported anxiety levels. In this study, endogenous oxytocin and sex hormone levels were analyzed in 99 high (51 women) and 100 low (50 women) socially anxious individuals. Regression analyses showed that women with high oxytocin and estradiol levels reported a lower total Liebowitz Social Anxiety Score (LSAS) as well as a lower score on the subscale LSAS Fear. This association of hormonal interaction with social anxiety scores was significant in the subsample of high socially anxious women. In men there were no significant associations for endogenous hormones with LSAS scores. These findings suggest that in women the link between oxytocin and anxiety might be dependent on basal anxiety levels as well as on individual sex hormone levels.

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 Signaling Pathway: From Cell Biology to Clinical Implications

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Intranasal oxytocin has sympathoexcitatory effects on vascular tone in healthy males

Oxytocin appears to be involved in the neuroendocrine regulation of sympathetic blood pressure (BP) homeostasis. In animals, intracerebral administration of oxytocin induces BP-relevant sympathetic activation. In humans, central nervous effects of oxytocin on BP regulation remain unclear. Intranasal administration supposedly delivers oligopeptides such as oxytocin directly to the brain. We investigated the effects of intranasal oxytocin on sympathetic vascular baroreflex function in humans using microneurographic techniques. In a balanced, double-blind crossover design, oxytocin or placebo was administered intranasally to 12 lean, healthy males (age 25 ± 4 yr). Muscle sympathetic nerve activity (MSNA) was assessed microneurographically before (presubstance), 30-45 min (postsubstance I), and 105-120 min (postsubstance II) after oxytocin administration. Baroreflex was challenged via graded infusions of vasoactive drugs, and correlation of BP with MSNA and heart rate (HR) defined baroreflex function. Experiments were conducted in the afternoon after a 5-h fasting period. After oxytocin, resting MSNA (burst rate and total activity) showed significant net increases from pre to postsubstance II compared with placebo [Δincrease = +4.3 ± 1.2 (oxytocin) vs. +2.2 ± 1.4 bursts/min (placebo), ANOVA; P < 0.05; total activity = 184 ± 11.5% (oxytocin) vs. 121 ± 14.3% (placebo), ANOVA; P = 0.01). This was combined with a small but significant net increase in resting diastolic BP, whereas systolic and mean arterial BP or HR as well as baroreflex sensitivity at vasoactive drug challenge were not altered. Intranasally administered oxytocin induced vasoconstrictory sympathoactivation in healthy male humans. The concomitant increase of diastolic BP was most likely attributable to increased vascular tone. This suggests oxytocin-mediated upward resetting of the vascular baroreflex set point at centers superordinate to the mere baroreflex-feedback loop.

Phenomenological Experiences during Active-Alert Hypnosis: Comparison of Hypnotist and Subject

There has been increasing clinical interest in active-alert hypnosis (AAH). However, relatively few studies have been devoted to studying its properties systematically. The present study compared the subjective experiences of subjects (31) and hypnotists (5) during AAH, using Pekala's Phenomenology of Consciousness Inventory (PCI), the Dyadic Interactional Harmony (DIH) scale and the Archaic Involvement Measure (AIM). Results demonstrated similarities between the experiences of subjects and hypnotists. The only significant difference between the subjects' and the hypnotists' experiences was shown by the PCI, which highlighted the differences stemming from the different roles of hypnotist and subject during the AAH. The study suggests it may be important to examine subjective descriptors in the exploration of personal experiences in studies of AAH.

Enhancing prolonged exposure therapy for PTSD among veterans with oxytocin: Design of a multisite randomized controlled trial

Posttraumatic stress disorder (PTSD) is the most highly prevalent mental health disorder among U.S. military Veterans. Prolonged Exposure (PE) therapy is one of the most widely used evidence-based treatments for PTSD, but there is substantial room for improvement in outcomes and retention rates. Accumulating data suggest that oxytocin offers a promising pharmacological approach towards achieving this goal. Therefore, the primary objective of this two-site Phase II study is to examine the ability of oxytocin (vs. placebo) administration combined with PE therapy to (1) reduce PTSD symptom severity, (2) accelerate the rate of PTSD symptom improvement, and (3) improve PE adherence and retention rates. To accomplish these objectives, we will employ a randomized, double-blind, placebo-controlled trial and use standardized, repeated dependent measures of change at five time points (baseline, mid-treatment, end of treatment, and 3 and 6 month follow-up). Intranasal oxytocin (40 IU) will be administered directly prior to each PE therapy session. Findings from this study will provide critical new information regarding the efficacy of oxytocin to augment psychosocial treatment for PTSD, as well as information regarding the physiological mechanisms underlying PTSD and positive treatment response. ClinicalTrials.gov Identifier: NCT04228289.

The moderating role of infidelity on the relation between oxytocin and conflict behaviors among substance misusing couples

The neuropeptide oxytocin (OT) may be beneficial to augmenting behavioral therapies for couples given its ability to alleviate stress reactivity and increase pro-social behavior. However, there is growing evidence demonstrating inconsistent effects of OT on social behavior. Infidelity may represent a relational vulnerability that modulates the OT response. The present study hypothesized that actor and partner emotional and physical infidelity would be associated with less adaptive conflict behaviors, and moderate the OT response, such that participants randomized to a OT condition, compared to placebo, who report more infidelity would show less adaptive conflict behaviors. Participants were 30 couples (N = 60) wherein one or both partners engaged in recent hazardous drinking or illicit drug use. Partners completed a 10-min dyadic conflict task in the laboratory, self-administered a single intranasal dose of OT (40 IU) or placebo, and then completed the same 10-min dyadic conflict task following a 45-min wait period. Couple conflict behaviors were observed during the conflict tasks and assessed using a validated coding system. Actor partner interdependence models detected significant interactions between drug condition and physical infidelity, such that among individuals in the OT group, verses individuals in the placebo group, (a) who reported greater physical infidelity had greater distress maintaining attributions and (b) whose partners reported greater physical infidelity had fewer relationship enhancing attributions. Results are consistent with the social salience hypothesis of OT and suggest that physical infidelity appears to serve as a contextual vulnerability that may decreases positive and increase negative behaviors during conflict. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

The oxytocinergic system in PTSD following traumatic childbirth: endogenous and exogenous oxytocin in the peripartum period

Birth experiences can be traumatic and may give rise to PTSD following childbirth (PTSD-FC). Peripartum neurobiological alterations in the oxytocinergic system are highly relevant for postpartum maternal behavioral and affective adaptions like bonding and lactation but are also implicated in the response to traumatic events. Animal models demonstrated that peripartum stress impairs beneficial maternal postpartum behavior. Early postpartum activation of the oxytocinergic system may, however, reverse these effects and thereby prevent adverse long-term consequences for both mother and infant. In this narrative review, we discuss the impact of trauma and PTSD-FC on normal endogenous oxytocinergic system fluctuations in the peripartum period. We also specifically focus on the potential of exogenous oxytocin (OT) to prevent and treat PTSD-FC. No trials of exogenous OT after traumatic childbirth and PTSD-FC were available. Evidence from non-obstetric PTSD samples and from postpartum healthy or depressed samples implies restorative functional neuroanatomic and psychological effects of exogenous OT such as improved PTSD symptoms and better mother-to-infant bonding, decreased limbic activation, and restored responsiveness in dopaminergic reward regions. Adverse effects of intranasal OT on mood and the increased fear processing and reduced top-down control over amygdala activation in women with acute trauma exposure or postpartum depression, however, warrant cautionary use of intranasal OT. Observational and experimental studies into the role of the endogenous and exogenous oxytocinergic system in PTSD-FC are needed and should explore individual and situational circumstances, including level of acute distress, intrapartum exogenous OT exposure, or history of childhood trauma.

Oxytocin & well-being as promoters of affect regulation and homeostasis: a neuroscientific review

Neurohormone oxytocin release affects mood and behavior in humans, regulating emotional and physiologic aspects.  Neuroscience associates well-being to oxytocin to characterize a general positive-valenced emotional state.  However, the terms well-being and oxytocin are absent, or present in a limited way, in most indexes of psychological terminology and health science descriptors.  This study aimed at studying how this association occurs in literature, based on a systematic review on oxytocin and well-being in the last five years.  Main results: the neuroscientific context seemed to be the most adequate to the study between oxytocin and well-being; association between psychological and neuroendocrine aspects was unusual; medical templates predominated over psychological references;  oxytocin release and feelings of well-being were associated to stimuli of the affective-sensorial type, to psychiatric interventions, to familiarity; results varied according to age, gender, context and personality.  

Mothers' and fathers' joint profiles for testosterone and oxytocin in a small-scale fishing-farming community: Variation based on marital conflict and paternal contributions

INTRODUCTION

Testosterone and oxytocin are psychobiological mechanisms that interrelate with relationship quality between parents and the quantity and quality of parenting behaviors, thereby affecting child outcomes. Their joint production based on family dynamics has rarely been tested, particularly cross-culturally.

METHODS

We explored family function and salivary testosterone and oxytocin in mothers and fathers in a small-scale, fishing-farming society in Republic of the Congo. Fathers ranked one another in three domains of family life pertaining to the local cultural model of fatherhood.

RESULTS

Fathers who were viewed as better providers had relatively lower oxytocin and higher testosterone than men seen as poorer providers, who had lower testosterone and higher oxytocin. Fathers also had higher testosterone and lower oxytocin in marriages with more conflict, while those who had less marital conflict had reduced testosterone and higher oxytocin. In contrast, mothers in conflicted marriages showed the opposite profiles of relatively lower testosterone and higher oxytocin. Mothers had higher oxytocin and lower testosterone if fathers were uninvolved as direct caregivers, while mothers showed an opposing pattern for the two hormones if fathers were seen as involved with direct care.

CONCLUSIONS

These results shed new light on parents' dual oxytocin and testosterone profiles in a small-scale society setting and highlight the flexibility of human parental psychobiology when fathers' roles and functions within families differ across cultures.

Oxytocin Modulates the Cognitive Appraisal of the Own and Others Close Intimate Relationships

Close and intimate relationships are important promoters of health. Oxytocin and its association with social cognition have been investigated in a large number of studies, especially highlighting the neuropeptide's involvement in attachment behavior and intimate relationships. However, mixed findings on exogenous oxytocin application have led to the focus on moderators and mediators, suggesting that the effects are depended on specific factors - namely context and salience. The objective of the current study was to assess the effect of intranasal oxytocin on social appraisal of own and others' close intimate relationship characteristics. Different characteristics of relationships, including trust or closeness, between romantic couples (unknown and own) were assessed using the Couple Appraisal Task. In a randomized controlled double-blind cross-over within subject design, N = 71 healthy men and women were investigated after receiving first intranasal oxytocin and 2 weeks later placebo, or vice versa. We found an oxytocin-induced increase in the positive appraisal of one's own overall relationship characteristics but not in the evaluation of the relationship of others. The present study - one of the first of its kind administrating oxytocin in a repeated measures cross-over design - adds further evidence to the mediating role of oxytocin in social cognition, specifically with regard to romantic relationship characteristics.

Design of a randomized controlled trial examining the efficacy of oxytocin to enhance alcohol behavioral couple therapy

Combining pharmacological interventions with evidence-based behavioral interventions may help optimize treatment outcomes for alcohol use disorder (AUD). While several effective behavioral interventions for AUD have been developed, the vast majority target individual patients, despite evidence that behavioral interventions for couples have the ability to outperform individual treatments for AUD. Alcohol Behavioral Couples Therapy (ABCT) is an evidence-based behavioral intervention for couples that has been shown to significantly reduce AUD severity as well as improve relationship functioning. Accumulating evidence suggests that the neuropeptide oxytocin has the ability to reduce alcohol craving and consumption, symptoms of tolerance and withdrawal, and ameliorate neurobiological deficits associated with AUD. Furthermore, oxytocin has demonstrated the ability to increase prosocial behavior and cognition, and restore sensitivity to natural rewards such as interpersonal relationships. No study to date has examined the ability of oxytocin to enhance ABCT. Thus, the primary objective of this Phase II study is to examine the effects of oxytocin versus placebo in combination with ABCT in reducing AUD severity and improving relationship functioning. We also will utilize neuroimaging techniques before and after treatment to investigate the underlying pathophysiology of AUD among couples and identify prognostic indicators of treatment outcome. The findings from this study might provide critical new information to help inform clinical practice and accelerate research on the pharmacological treatment of AUD.

Impact of Oxytocin on the neural correlates of fearful face processing in PTSD related to childhood Trauma

Background: Posttraumatic stress disorder (PTSD) related to exposure to abuse and neglect during childhood is associated with particularly severe and persistent deleterious outcomes. Amygdala hyperreactivity has been observed in childhood trauma survivors and implicated in symptoms of PTSD. Objective: The neuropeptide oxytocin holds promise as a potential treatment for PTSD due to its ability to attenuate amygdala response to threat cues. However, the effect of oxytocin on amygdala reactivity in individuals with childhood trauma-related PTSD has not been investigated. Method: We employed a double-blind, randomized, placebo-controlled crossover design to examine the effects of intranasal oxytocin (24 IU) versus placebo on amygdala reactivity to fearful faces among childhood-trauma exposed individuals with PTSD (n = 17) and without PTSD (control group; n = 16). Results: Region-of-interest based amygdala fMRI signal magnitude did not differ by group, drug, or group x drug interaction. Self-report of childhood trauma exposure severity was negatively associated with the oxytocin-related change in left amygdala response in the PTSD group, but not in the control group. Supplementary and exploratory whole-brain analyses conducted separately in each group revealed that left amygdala reactivity to fearful faces was absent on placebo but increased on oxytocin in the control group. The PTSD group showed right amygdala activation to fearful faces in both the oxytocin and placebo conditions, but the left amygdala response observed in the placebo condition was diminished on oxytocin. Conclusions: Findings extend the literature pertaining to the potential for oxytocin to attenuate neural correlates of PTSD to a childhood trauma-related PTSD sample.

Sex-specific Effects of Music Listening on Couples' Stress in Everyday Life

Music listening in daily life is associated with stress-reducing effects on the individual with increasing effects when music listening occurs in a social context. As little is known about effects on couples, we investigated whether beneficial effects can be found in couples. Forty heterosexual couples were investigated using ambulatory assessment. Participants completed six assessments on music listening and subjective stress per day for five consecutive days. With each assessment, saliva samples for the later analysis of cortisol and alpha-amylase were collected. Music listening affected biopsychological stress markers in women and men, however in different ways: While music listening reduced cortisol in women, it increased alpha-amylase in men. Dyadic effects of music listening on stress markers were found. Men showed lower secretion of cortisol if women listened to music which was more pronounced when couples shared musical preferences. Both men and women showed higher alpha-amylase activity when their partner had listened to music. Music listening influences couples’ psychobiological stress levels in a sex-dependent manner with evidence of dyadic co-variation in physiological responses to music. Interventions for promoting stress reduction should consider that women and men differ in their use of music in everyday life.

Effects of Oxytocin on Emotional and Physiological Responses to Conflict in Couples with Substance Misuse

Social stress, especially dyadic conflict among couples, is an important correlate of addiction. Several authors have suggested that the neuropeptide oxytocin (OT) may be useful in the treatment of couples with substance misuse. However, the literature examining OT among couples is scant and has yielded mixed findings. The current study examined the effects of OT versus placebo on emotional (e.g., warmth and anger) and physiological (e.g., skin conductance and heart rate) reactivity to a conflict resolution task in 30 heterosexual couples (N=60) in which one or both members misused substances. Using a randomized, double-blind, placebo-controlled design, both partners within each dyad were randomized to the same treatment condition. Participants completed a standardized conflict resolution task at baseline and 45 minutes following drug self-administration. Physiological measures were examined continuously during the laboratory tasks and emotional reactivity was self-reported at baseline and at 5 time points over the course of 1 hour following the second conflict resolution task. Results of a multi-level growth curve model accounting for baseline scores, gender and drug condition indicate that positive emotional experiences and skin conductance measures increased over the 5 time points. Neither drug condition nor gender was significantly related to outcomes, and no interaction effects were observed. These findings highlight the complexities involved in translational OT research and suggest that the impact of OT on key outcomes requires further exploration in regards to OT's potential therapeutic benefit.

Effects of oxytocin on stress reactivity and craving in veterans with co-occurring PTSD and alcohol use disorder

Posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) are highly prevalent and commonly co-occur. The dual diagnosis of PTSD/AUD is associated with serious negative sequalae, and there are currently no effective pharmacological treatments for this comorbidity. Both PTSD and AUD are characterized by dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which helps modulate stress reactivity. Oxytocin, a neuropeptide that attenuates HPA axis dysregulation, may be beneficial for individuals with co-occurring PTSD/AUD. Thus, the current study examined the effects of intranasal oxytocin (40 IU) as compared with placebo on stress reactivity (e.g., cortisol) as well as subjective alcohol craving in response to a laboratory stress task (Trier Social Stress Task). Participants were 67 male U.S. military veterans with current PTSD and AUD (oxytocin n = 32, placebo n = 35; overall mean age = 49.06 years). Baseline cortisol levels were examined as a moderator of outcome. The findings revealed that oxytocin marginally attenuated cortisol reactivity in response to the stress task. Furthermore, oxytocin's effect was moderated by baseline cortisol level, such that oxytocin mitigated cortisol reactivity to a greater extent among participants with higher, as compared with lower, baseline cortisol. Oxytocin did not reduce craving. Although preliminary, the findings are the first to examine oxytocin in co-occurring PTSD/AUD. The findings from this study contribute to the growing literature examining the potential utility of oxytocin among individuals with psychiatric disorders, such as PTSD and substance use disorders. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Dyadic Coping and Its Underlying Neuroendocrine Mechanisms - Implications for Stress Regulation

Previous research suggests that neuroendocrine mechanisms underlie inter-individual stress coping in couples. The neuropeptide oxytocin (OT), while regulating stress-sensitive HPA-axis activity might be crucial in this process. The purpose of this study was to examine the impact of dyadic coping abilities and OT on HPA-axis outcomes and constructive behavior during couple conflict. We conducted a secondary analysis of our previous database (Ditzen et al., 2009), assessing the modulating role of dyadic coping and intranasal OT on couple conflict behavior. The data revealed a significant interaction effect of the dyadic coping by oneself score and OT on cortisol responses during couple conflict, suggesting that particularly individuals with low a priori dyadic coping benefit from OT in terms of dampened HPA-activity. The results are in line with previous research suggesting OT’s central role for stress regulation and prosocial behavior. Furthermore, an interaction with dyadic coping indicates adaptations in the sensitivity of the OT system during the individual attachment and relationship history. These data add to the evidence that the neuroendocrine attachment systems influence couple behavior. Future studies of neurobiological mechanisms underlying dyadic coping will be of high relevance for the development of prevention and intervention programs.

Intimacy as Related to Cortisol Reactivity and Recovery in Couples Undergoing Psychosocial Stress

OBJECTIVE

The importance of recovery from stress is evident in times of high prevalence of stress-related diseases. Intimacy has been found to buffer psychobiological stress reactivity, suggesting that emotional and physical closeness might trigger biological mechanisms that underlie the health-beneficial effects of couple relationships. Here, we investigated whether couples' spontaneous expression of intimacy before and after psychosocial stress exposure in the laboratory reduced cortisol reactivity and accelerated recovery.

METHODS

Data from 183 couples (366 individuals) were analyzed. Couples were randomly assigned to one of the following three experimental conditions: only the female partner (n = 62), only the male partner (n = 61), or both partners were stressed in parallel (n = 60) with the Trier Social Stress Test. Couples' behavior was videotaped and coded for expressions of intimacy, and saliva samples were taken repeatedly (nine times) to analyze cortisol levels before and after stress. Data were analyzed using hierarchical linear modeling.

RESULTS

Observed partner intimacy reduced cortisol responses to stress in women (B = -0.016, SE = 0.006, p = .008), although this effect was eliminated among women using oral contraceptives. Observed partner intimacy also reliably accelerated cortisol recovery in men (B = -0.002, SE = 0.001, p = .023) and women (B = -0.002, SE = 0.001, p = .016).

CONCLUSIONS

Spontaneous nonverbal expressions of intimacy seem to regulate the effects of acute environmental demands on established biological indices of stress response.

Menstrual cycle-related fluctuations in oxytocin concentrations: A systematic review and meta-analysis

Oxytocin affects physiological and psychological functions that are often expressed sex-specifically, suggesting interactions between oxytocin and sex hormones. As female sex hormone concentrations change during the menstrual cycle, oxytocin might fluctuate, too. This systematic review and meta-analysis investigated endogenous oxytocin concentrations across menstrual cycle phases in healthy women. Data from 13 studies (120 women) showed a significant increase of oxytocin concentrations from the early follicular phase to ovulation (g = 0.39 [0.25; 0.53], p < .001) and a significant decrease from ovulation to the mid-luteal phase (g = -0.50 [-0.81; -0.18], p < .001). There were no significant differences between the early follicular and mid-luteal phase (g = -0.19 [-0.70; -0.32], p = .471). These findings contribute to a deeper understanding of differences in normal and abnormal psychobiological processes in women. They highlight the necessity to consider the menstrual cycle phase in studies on oxytocin in women.

Oxytocin and vasopressin increase male-directed threats and vocalizations in female macaques

In a previous study, we reported that intranasal delivery of both oxytocin (OT) and arginine vasopressin (AVP) to male macaques relaxes spontaneous social interactions, flattens the existing dominance hierarchy, and increases behavioral synchrony with other monkeys. Here we report that intranasal OT and AVP administration modulates the behaviors of female macaque monkeys, but in robustly different ways from males. Most notably, both neuropeptides increase threatening and vocalization behaviors of females when they encounter males, and these behaviors effectively increase the social status of females over males. While OT and AVP heighten the confrontational nature of intersexual encounters, both peptides relax interactions between females. Finally, as previously reported for males, treating an individual female monkey with OT or AVP significantly modulates the behavior of her non-treated partner. Together, these findings show that OT and AVP can either inhibit or promote aggression, depending on sex and behavioral context, and call for a more careful, systematic examination of the functions of these neuropeptides in both sexes, especially in the context of therapeutics for human social disorders.

Intimate partner violence moderates the association between oxytocin and reactivity to dyadic conflict among couples

Emerging literature indicates individual and contextual differences impact response to oxytocin (OT). Intimate partner violence (IPV) is one chronic stressor that may moderate OT response. To test the hypothesis that IPV moderates the association between OT and reactivity to a dyadic conflict task, data from a larger randomized controlled study was collected from heterosexual couples (N = 60 individuals; 30 couples) at high risk for IPV due to substance misuse. Partners within each dyad completed a 10-minute dyadic conflict task in the laboratory, and then self-administered a single dose of OT (40 IU) or placebo. Forty-five minutes later, participants completed another 10-minute dyadic conflict task. Stress reactivity was measured before and after the second conflict task using neuroendocrine (i.e., salivary cortisol), physiological (i.e., skin conductance), and subjective responses. Couple conflict behaviors were observed during the conflict tasks and assessed using a validated coding system. Among women, physical IPV modulated skin conductance in those administered OT, and OT interacted with physical and psychological IPV to yield less positive subjective and behavioral responses. No main or moderating effects were found for men. Findings support emerging literature on sex differences in response to OT. Future research is needed to effectively translate OT into therapeutic intervention.

Oxytocin increases eye-gaze towards novel social and non-social stimuli

Research on oxytocin (OT) has revealed a substantial involvement of this neuropeptide in social cognition processes and attachment behavior. The rationale of the present project was to decipher the differential role of OT in basic social cognition processes towards non-erotic attachment stimuli vs. reproduction-related stimuli in human subjects. In a randomized double-blind repeated-measures cross-over design, N = 82 participants were investigated twice and received either intranasal OT or placebo at the first assessment followed by placebo or OT at second assessment. Participants were presented with standardized pictures of parent-child dyads, romantic couples engaging in non-erotic or explicit sexual activities, and non-social pictures while we assessed pupil dilation and eye focus on specific pre-defined areas of interest. Multilevel analyses suggest that during the initial presentation, OT increased pupil dilation towards all categories of stimuli and led the eye focus towards the eyes and body regions, followed by a strong decrease in pupil dilation and fixations at the second session. These carry-over effects indicate that hormonal treatment at an initial contact to social stimuli can determine how these stimuli are processed later. These results might have implications for OT as a treatment in interventions with repeated exposure to social material.

CHANGES IN OXYTOCIN AND CORTISOL IN ACTIVE-ALERT HYPNOSIS: Hormonal Changes Benefiting Low Hypnotizable Participants

It is increasingly clear that oxytocin and cortisol play an intricate role in the regulation of behavior and emotions impacting health, relationships, and well-being. Their long-term, cross-generational effect makes them an important focus of the present study. This exploratory research examined changes in oxytocin and cortisol levels and their correlations with different phenomenological measures in both hypnotist and subject during active-alert hypnosis. The level of oxytocin increased whereas the level of cortisol decreased in the hypnotist. When comparing the oxytocin changes of subjects with their hypnotizability, those with low hypnotizability scores experienced an increase in oxytocin, and those with medium and high hypnotizability scores showed no change or decrease. This could explain why clients' hypnotizability is not considered an important factor during hypnotherapy.

Effects of oxytocin on working memory and executive control system connectivity in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a chronic, debilitating condition for which effective medications are scant and little is known about neural correlates of risk versus resilience. Oxytocin is a hypothalamic neuropeptide that has demonstrated promise in modulating neurobiological and behavioral correlates of PTSD. Cognitive deficits in areas such as working memory and executive control are highly prevalent among individuals with PTSD and oxytocin might modulate these impairments in individuals with PTSD. Using a double-blind, placebo-controlled design, this study employed functional MRI (fMRI) and the n-back working memory task to examine the effects of oxytocin (24 IU) versus placebo on working memory and dorsolateral prefrontal cortex (DLPFC) connectivity among individuals with PTSD (n = 16) as compared with a trauma-exposed control group (n = 18). Results indicate that individuals with PTSD on oxytocin performed better in the 2-back condition of the n-back task compared with individuals with PTSD on placebo. Results also indicate that connectivity between DLPFC and anterior cingulate increased in the 2-back condition among individuals with PTSD on oxytocin as compared with placebo. These findings provide preliminary evidence of an effect of oxytocin on working memory among individuals with PTSD and insights into the neurobiological mechanisms underlying this association. Future studies are necessary to understand the mechanisms responsible for working memory deficits in PTSD and to examine the potential of oxytocin for use as a treatment for PTSD. (PsycINFO Database Record

Augmenting Prolonged Exposure therapy for PTSD with intranasal oxytocin: A randomized, placebo-controlled pilot trial

Posttraumatic stress disorder (PTSD) is a chronic, debilitating condition for which Prolonged Exposure (PE) therapy is highly efficacious. However, for some individuals, premature dropout and residual PTSD symptoms remain obstacles. The neuropeptide oxytocin is a promising candidate to enhance PE due to its ability to enhance 1) prosocial cognition and behavior, which are theorized to promote positive working alliance, and 2) extinction learning, which is the central mechanism of action underlying successful PE treatment. Despite a robust theoretical rationale, no studies to date have combined evidence-based psychotherapy for PTSD with oxytocin. This randomized, placebo-controlled, double-blind pilot trial examined the feasibility, safety, and preliminary efficacy of augmenting PE with oxytocin. Participants were 17 individuals with diverse index traumas. Participants self-administered intranasal oxytocin (40 IU) or matching placebo 45 min prior to each weekly PE therapy session. One adverse event occurred in the placebo group and three individuals dropped out (17.6%; 2 oxytocin group and 1 placebo group). The oxytocin group demonstrated lower PTSD and depression symptoms during PE, and had higher working alliance scores, although these differences did not reach statistical significance. Although preliminary, the findings support the feasibility of oxytocin combined with PE. Adequately powered studies are necessary to determine whether oxytocin enhances PE treatment outcomes and to examine potential mechanisms, such as accelerating extinction learning, enhancing early response, and preventing premature dropout. NCT03238924.

The effect of intranasal oxytocin on neural response to facial emotions in healthy adults as measured by functional MRI: A systematic review

Abnormalities in responses to human facial emotions are associated with a range of psychiatric disorders. Addressing these abnormalities may therefore have significant clinical applications. Previous meta-analyses have demonstrated effects of the neuropeptide oxytocin on behavioural response to facial emotions, and effects on brain, as measured by functional MRI. Evidence suggests that these effects may be mediated by sex and the role of eye gaze. However, the specific effect of oxytocin on brain response to facial emotions in healthy adults has not been systematically analysed. To address this question, this further systematic review was conducted. Twenty-two studies met our inclusion criteria. In men, oxytocin consistently attenuated brain activity in response to negative emotional faces, particularly fear, compared with placebo, while in women, oxytocin enhanced activity. Brain regions consistently involved included the amygdala, fusiform gyrus and anterior cingulate cortex. In some studies, oxytocin increased fixation changes towards the eyes with enhanced amygdala and/or fusiform gyrus activation. By enhancing understanding of emotion processing in healthy subjects, these pharmacoimaging studies provide a theoretical basis for studying deficits in clinical populations. However, progress to date has been limited by low statistical power, methodological heterogeneity, and a lack of multimodal studies.