Anxiolytic-like effect of oxytocin in the simulated public speaking test

The interaction of oxytocin and nicotine addiction on psychosocial stress: an fMRI study

The anxiolytic effect of oxytocin (OXT) on psychosocial stress has been well documented, but the effectiveness under the interference of other factors still requires in-depth research. Previous studies have shown that nicotine addiction interacts with OXT on psychosocial stress on the behavioral level. However, the underlying neural mechanism of interaction between OXT and nicotine addiction on psychosocial stress has not been examined, and we conducted two experiments to reveal it. Firstly, after intranasal administration of randomized OXT or placebo (saline), a group of healthy participants (n = 27) and a group of smokers (n = 26) completed the Montreal Imaging Stress Task (MIST) in an MRI scanner. Secondly, a group of smokers (n = 22) was recruited to complete a transcranial direct current stimulation (tDCS) experiment, in which anodal tDCS was applied on subjects' anterior right superior temporal gyrus (rSTG). In both experiment, subjective stress ratings, salivary cortisol samples and the amount of daily cigarette consumption were obtained from each participant. Analysis of variance were applied on both behavioral and neural data to examine the effects of OXT and nicotine addiction, and correlation analysis were used to examine relationships between neural and behavioral data. In first fMRI experiment, analysis of variance (ANOVA) revealed an interaction of OXT and nicotine addiction on subjective stress. In smokers, OXT failed to suppress the elevation of subjective stress and craving ratings after psychosocial stress. A voxel-wise ANOVA of fMRI data identified an interaction between OXT and nicotine addiction in anterior rSTG, and its functional connectivity with right middle frontal gyrus. Correlations between this functional connectivity and subjective psychosocial stress were also found abnormal in smokers. In second tDCS experiment, we found that under tDCS, OXT successfully suppressed the elevation of subjective stress and craving ratings after stress. In summary, we found that nicotine addiction blocked OXT's anxiolytic on psychosocial stress, which was related to abnormalities in anterior rSTG. By applying anodal tDCS on anterior rSTG, OXT's anxiolytic effect was restored in smokers. These findings will support further development on oxytocin's intervention of psychosocial stress in nicotine addiction, and provides essential information for indicating OXT's effectiveness.

Potential role of oxytocin in the regulation of memories and treatment of memory disorders

Oxytocin (OXT) is an "affiliative" hormone or neurohormone or neuropeptide consists of nine amino acids, synthesized in magnocellular neurons of paraventricular (PVN) and supraoptic nuclei (SON) of hypothalamus. OXT receptors are widely distributed in various region of brain and OXT has been shown to regulate various social and nonsocial behavior. Hippocampus is the main region which regulates the learning and memory. Hippocampus particularly regulates the acquisition of new memories and retention of acquired memories. OXT has been shown to regulate the synaptic plasticity, neurogenesis, and consolidation of memories. Further, findings from both preclinical and clinical studies have suggested that the OXT treatment improves performance in memory related task. Various trials have suggested the positive impact of intranasal OXT in the dementia patients. However, these studies are limited in number. In the present study authors have highlighted the role of OXT in the formation and retrieval of memories. Further, the study demonstrated the outcome of OXT treatment in various memory and related disorders.

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 modulates neural activity during early perceptual salience attribution

Leading hypotheses of oxytocin's (OT) role in human cognition posit that it enhances salience attribution. However, whether OT exerts its effects predominantly in social (vs non-social) contexts remains debatable, and the time-course of intranasal OT's effects' on salience attribution processing is still unknown. We used the social Salience Attribution Task modified (sSAT) in a double-blind, placebo-controlled intranasal OT (inOT) administration, between-subjects design, with 54 male participants, to test existing theories of OT's role in cognition. Namely, we aimed to test whether inOT would differently affect salience attribution processing of social stimuli (expressing fearfulness) and non-social stimuli (fruits) made relevant via monetary reinforcement, and its neural processing time-course. During electroencephalography (EEG) recording, participants made speeded responses to emotional social (fearful faces) and non-emotional non-social (fruits) stimuli - which were matched for task-relevant motivational salience through their (color-dependent) probability of monetary reinforcement. InOT affected early (rather than late, P3b and LPP) EEG components, increasing N170 amplitude (p = .041) and P2b latency (p .001; albeit not of P1), regardless of stimuli's (emotional) socialness or reinforcement probability. Fear-related socialness affected salience attribution processing EEG (p .05) across time (N170, P2b and P3b), being later modulated by reinforcement probability (LPP). Our data suggest that OT's effects on neural activity during early perception, may exist irrespective of fear-related social- or reward-contexts. This partially supports the tri-phasic model of OT (which posits OT enhances salience attribution in an early perception stage regardless of socialness), and not the social salience nor the general approach-withdrawal hypotheses of OT, for early salience processing event-related potentials.

Oxytocin Attenuates Yohimbine-Induced Reinstatement of Alcohol-Seeking in Female Rats via the Central Amygdala

Alcohol use disorder is a significant public health concern, further exacerbated by an increased risk of relapse due to stress. In addition, factors such as biological sex may contribute to the progression of addiction, as females are especially susceptible to stress-induced relapse. While there have been many studies surrounding potential pharmacological interventions for male stress-induced ethanol reinstatement, research regarding females is scarce. Recently, the neuropeptide oxytocin has gained interest as a possible pharmacological intervention for relapse. The present study examines how oxytocin affects yohimbine-induced reinstatement of ethanol-seeking in female rats using a self-administration paradigm. Adult female rats were trained to press a lever to access ethanol in daily self-administration sessions. Rats then underwent extinction training before a yohimbine-induced reinstatement test. Rats administered with yohimbine demonstrated significantly higher lever response indicating a reinstatement of ethanol-seeking behavior. Oxytocin administration, both systemically and directly into the central amygdala, attenuated the effect of yohimbine-induced reinstatement of ethanol-seeking behavior. The findings from this study establish that oxytocin is effective at attenuating alcohol-relapse behavior mediated by the pharmacological stressor yohimbine and that this effect is modulated by the central amygdala in females. This provides valuable insight regarding oxytocin's potential therapeutic effect in female stress-induced alcohol relapse.

Perinatal high-fat diet exposure alters oxytocin and corticotropin releasing factor inputs onto vagal neurocircuits controlling gastric motility

Perinatal high-fat diet (pHFD) exposure alters the development of vagal neurocircuits that control gastrointestinal (GI) motility and reduce stress resiliency in offspring. Descending oxytocin (OXT; prototypical anti-stress peptide) and corticotropin releasing factor (CRF; prototypical stress peptide) inputs from the paraventricular nucleus (PVN) of the hypothalamus to the dorsal motor nucleus of the vagus (DMV) modulate the GI stress response. How these descending inputs, and their associated changes to GI motility and stress responses, are altered following pHFD exposure are, however, unknown. The present study used retrograde neuronal tracing experiments, cerebrospinal fluid extraction, in vivo recordings of gastric tone, motility and gastric emptying rates, and in vitro electrophysiological recordings from brainstem slice preparations to investigate the hypothesis that pHFD alters descending PVN-DMV inputs and dysregulates vagal brain-gut responses to stress. Compared to controls, rats exposed to pHFD had slower gastric emptying rates and did not respond to acute stress with the expected delay in gastric emptying. Neuronal tracing experiments demonstrated that pHFD reduced the number of PVNOXT neurons that project to the DMV, but increased PVNCRF neurons. Both in vitro electrophysiology recordings of DMV neurons and in vivo recordings of gastric motility and tone demonstrated that, following pHFD, PVNCRF -DMV projections were tonically active, and that pharmacological antagonism of brainstem CRF1 receptors restored the appropriate gastric response to brainstem OXT application. These results suggest that pHFD exposure disrupts descending PVN-DMV inputs, leading to a dysregulated vagal brain-gut response to stress. KEY POINTS: Maternal high-fat diet exposure is associated with gastric dysregulation and stress sensitivity in offspring. The present study demonstrates that perinatal high-fat diet exposure downregulates hypothalamic-vagal oxytocin (OXT) inputs but upregulates hypothalamic-vagal corticotropin releasing factor (CRF) inputs. Both in vitro and in vivo studies demonstrated that, following perinatal high-fat diet, CRF receptors were tonically active at NTS-DMV synapses, and that pharmacological antagonism of these receptors restored the appropriate gastric response to OXT. The current study suggests that perinatal high-fat diet exposure disrupts descending PVN-DMV inputs, leading to a dysregulated vagal brain-gut response to stress.

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 on the self-perception and anxiety of singers during a simulated public singing performance: A randomized, placebo-controlled trial

Professional musicians experience intense social exposure and high levels of preoccupation with their performance and potential negative reactions from the audience, which favor anxiety. Considering that oxytocin (OXT) has a potential therapeutic effect on anxiety, cognitive processes, and decreased psychosocial stress, this study's objective was to assess the effects of a single dose of 24 UI of intranasal OXT among professional singers, during a public singing simulation test, on self-rated performance and mood. This crossover, randomized, double-blinded, placebo-controlled trial addressed 54 male singers with different levels of musical performance anxiety (42% high). The participants took part in different phases of a simulated public singing performance and completed instruments rating their performances (Self Statements During Public Performance- State version) and mood (Visual Analogue Mood Scale). Data were analyzed using ANOVA 2 × 2 for crossover trials. The results show that the use of OXT during the performance and immediate post-stress favored more positive (effect size: d > 1.04) and less negative assessments of musical performance (effect size: d > 1.86) than when placebo was used. No treatment effects were found in any VAMS subscales, indicating no direct anxiolytic effects. The conclusion is that OXT can minimizes social stress, especially during performances. This finding is exploratory and, if confirmed in future studies, may have relevance for musicians, especially those who constantly experience and recognize the impact of negative and catastrophic thoughts on performance and professional activities.

Clinical Trial Registration

[https://ensaiosclinicos.gov.br/rg/RBR-5r5sc5], identifier [RBR-5r5sc5].

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Anxiolytic Effects of Chronic Intranasal Oxytocin on Neural Responses to Threat Are Dose-Frequency Dependent

INTRODUCTION

Anxiety disorders are prevalent mental conditions characterized by exaggerated anxious arousal and threat reactivity. Animal and human studies suggest an anxiolytic potential of the neuropeptide oxytocin (OT), yet, while a clinical application will require chronic administration protocols, previous human studies have exclusively focused on single-dose (acute) intranasal OT effects.

OBJECTIVE

To facilitate the translation of the potential anxiolytic mechanism of OT into clinical application, we determined whether the anxiolytic effects of OT are maintained with repeated (chronic) administration or are influenced by dose frequency and trait anxiety.

METHODS

In a pre-registered double-blind randomized placebo-controlled pharmaco-fMRI trial the acute (single dose) as well as chronic effects of two different dose frequencies of OT (OT administered daily for 5 days or every other day) on emotional reactivity were assessed in n = 147 individuals with high versus low trait anxiety (ClinicalTrials.gov ID: NCT03085654).

RESULTS

OT produced valence, dose frequency, and trait anxiety-specific effects, such that the low-frequency (intermittent) chronic dosage specifically attenuated a neural reactivity increase in amygdala-insula-prefrontal circuits observed in the high anxious placebo-treated subjects in response to threatening but not positive stimuli.

CONCLUSIONS

The present trial provides the first evidence that low-dose frequency chronic intranasal OT has the potential to alleviate exaggerated neural threat reactivity in subjects with elevated anxiety levels, suggesting a treatment potential for anxiety disorders.

Correlations of plasma oxytocin with clinical and hormonal parameters in panic disorder

AIMS

The potential association between oxytocin (OXT) plasma levels and clinical and hormonal parameters in panic disorder (PD) especially in its acute phase - has not been investigated as yet. This was the aim of this article.

METHOD

Twenty-four consecutively-referred, acutely-ill, medication-free PD patients with (PDA, N = 21) or without agoraphobia, moreover without comorbidities, completed the following clinical measures: Hamilton Anxiety Rating Scale (HARS); Agoraphobic Cognitions Questionnaire (ACQ); Mobility Inventory-Alone subscale (MI-alone); and number of panic attacks during last 21 d (PA21d). Plasma levels of OXT, adrenocorticotropic hormone (ACTH) and cortisol were evaluated.

RESULTS

OXT levels were significantly, negatively associated with the HARS scores (r= -0.59 p=.002) and weakly, negatively correlated with the ACQ scores (r = -0.403 p=.051). No significant correlations were traced between OXT levels and PA21d, MI-alone, ACTH, and cortisol.

CONCLUSION

In acutely-ill, medication-free PD patients, OXT plasma levels may be relevant to the severity of their 'general' anxiety symptoms, but not to the 'specific' panic psychopathology.

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.

Morphological changes in the basolateral amygdala and behavioral disruptions associated with social isolation

Social isolation and the disruption of established social bonds contribute to several physical and psychological health issues. Animal models are a useful tool for investigating consequences of social stress, including social isolation. The current study examined morphological changes in the basolateral amygdala (BLA) and affect-related behavioral and endocrine changes due to prolonged social isolation, using the translational prairie vole model (Microtus ochrogaster). Adult male prairie voles were either socially paired (control) or isolated from a same-sex sibling for 4 weeks. Following this 4-week period, a subset of animals (n = 6 per condition) underwent a series of behavioral tasks to assess affective, social, and stress-coping behaviors. Plasma was collected following the last behavioral task for stressor-induced endocrine assays. Brains were collected from a separate subset of animals (n = 10 per condition) following the 4-week social housing period for dendritic structure analyses in the BLA. Social isolation was associated with depressive- and anxiety-like behaviors, as well as elevated oxytocin reactivity following a social stressor. Social isolation was also associated with altered amount of dendritic material in the BLA, with an increase in spine density. These results provide further evidence that social isolation may lead to the development of affective disorders. Dysfunction in the oxytocin system and BLA remodeling may mediate these behavioral changes. Further research will promote an understanding of the connections between oxytocin function and structural changes in the BLA in the context of social stress. This research can facilitate novel treatments for alleviating or preventing behavioral and physiological consequences of social stressors in humans.

Oxytocin effects on the cognition of women with postpartum depression: A randomized, placebo-controlled clinical trial

BACKGROUND

One of the most common mental disorders in the perinatal period is postpartum depression (PPD), which is associated with impaired emotional functioning due to alterations in different cognitive aspects including thought and facial emotion recognition (FER). Emotional impairments may affect the interaction and care offered to infants and their later development and therefore interventions with potential to minimize impairments associated with PPD are opportune. Oxytocin (OXT) was shown to have therapeutic properties associated with the promotion of affiliative and pro-social behaviors in different mental disorders. Few studies have assessed its therapeutic potential in PPD.

OBJECTIVES

To assess the effects of the acute administration of intranasal OXT (24 IU) on FER of baby faces and negative thoughts after delivery in mothers with and without PPD.

METHODS

We conducted a randomized double-blind, placebo-controlled trial with a crossover design involving mothers with PPD (N = 20) and without PPD (N = 35) in the puerperium. Participants completed a static task of FER of baby faces and a questionnaire of post-natal negative thoughts.

RESULTS

Mothers with PPD had increased scores of negative thoughts about motherhood/infants, but no impairments in FER, when compared to healthy mothers. OXT had no effects on the rates of correct judgments or response times in the FER task, but was associated with response biases to facial happiness and the reduction of negative thoughts in mothers with PPD.

DISCUSSION/CONCLUSION

OXT may have positive effects on maternal affiliative behavior, maternal care, and mother-infant interactions as suggested by changes found in different cognitive aspects, thus minimizing the deleterious effects of PPD on child development.

Oxytocin Attenuates the Stress-Induced Reinstatement of Alcohol-Seeking in Male Rats: Role of the Central Amygdala

Factors such as stress and anxiety often contribute to alcohol-dependent behavior and can trigger a relapse of alcohol addiction and use. Therefore, it is important to investigate potential pharmacological interventions that may alleviate the influence of stress on addiction-related behaviors. Previous studies have demonstrated that the neuropeptide oxytocin has promising anxiolytic potential in mammals and may offer a pharmacological target to diminish the emotional impact on reinstatement of alcohol-seeking. The purpose of the present study was to investigate the effect of oxytocin on stress-induced alcohol relapse and identify a neural structure mediating this effect through the use of an ethanol self-administration and yohimbine-induced reinstatement paradigm. While yohimbine administration resulted in the reinstatement of ethanol-seeking behavior, the concurrent administration of yohimbine and oxytocin attenuated this effect, suggesting that oxytocin may disrupt stress-induced ethanol-seeking behavior. The central amygdala (CeA) is a structure that drives emotional responses and robustly expresses oxytocin receptors. Intra-CeA oxytocin similarly attenuated the yohimbine-induced reinstatement of ethanol-seeking behavior. These results demonstrate that oxytocin has the potential to attenuate stress-induced relapse into ethanol-seeking behavior, and that this mechanism occurs specifically within the central amygdala.

Dysphoric Milk Ejection Reflex: The Psychoneurobiology of the Breastfeeding Experience

Breastfeeding, given its biochemical and physiological basis, is known for its many benefits for both the lactating mother and the infant. Among the many challenges new breastfeeding mothers experience is the feeling of aversion in response to their newborn's suckling which has been termed dysphoric milk-ejection reflex (D-MER). Characterized by intense feelings of dysphoria which may eventually interfere with the mother's ability to breastfeed regularly, evidence suggests both the neurobiological and psychological basis of D-MER in an attempt to explain its complexity. Biologically, breastfeeding is expressed by the intracerebral release of oxytocin, an increased expression of oxytocin receptors in specific brain regions, increased mesocorticolimbic reward region activation, the secretion of prolactin and possibly the inhibition of dopamine. Hence, different theories explain D-MER in terms of disrupted neurotransmitter and hormonal activity. Breastfeeding has also proven to influence mood and stress reactivity in nursing mothers with a potential link with postpartum depression. Psychological theories attempt to explain D-MER from a sociopsychosexual lense shedding light on the significance of mother-infant attachment, the sexualization of the female body and the motherhood experience as a developmental stage in a woman's lifespan. The aim of this review is to provide a literature update of D-MER incorporating both neurobiological and psychological theories calling for raising awareness about the complexity of breastfeeding and for the need for mother-centered interventions for the management of D-MER and other postpartum-specific conditions.

An acute dose of intranasal oxytocin rapidly increases maternal communication and maintains maternal care in primiparous postpartum California mice

Maternal-offspring communication and care are essential for offspring survival. Oxytocin (OXT) is known for its role in initiation of maternal care, but whether OXT can rapidly influence maternal behavior or ultrasonic vocalizations (USVs; above 50 kHz) has not been examined. To test for rapid effects of OXT, California mouse mothers were administered an acute intranasal (IN) dose of OXT (0.8 IU/kg) or saline followed by a separation test with three phases: habituation with pups in a new testing chamber, separation via a wire mesh, and finally reunion with pups. We measured maternal care, maternal USVs, and pup USVs. In mothers, we primarily observed simple sweep USVs, a short downward sweeping call around 50 kHz, and in pups we only observed pup whines, a long call with multiple harmonics ranging from 20 kHz to 50 kHz. We found that IN OXT rapidly and selectively enhanced the normal increase in maternal simple sweep USVs when mothers had physical access to pups (habituation and reunion), but not when mothers were physically separated from pups. Frequency of mothers’ and pups’ USVs were correlated upon reunion, but IN OXT did not influence this correlation. Finally, mothers given IN OXT showed more efficient pup retrieval/carrying and greater total maternal care upon reunion. Behavioral changes were specific to maternal behaviors (e.g. retrievals) as mothers given IN OXT did not differ from controls in stress-related behaviors (e.g. freezing). Overall, these findings highlight the rapid effects and context-dependent effect a single treatment with IN OXT has on both maternal USV production and offspring care.

Intranasal oxytocin affects the stress response to social isolation in sheep

Oxytocin (OT) is a neuropeptide hormone that modulates several social behaviors and can affect the anxiety and stress response. The aim of this study was to determine if administration of intranasal OT affects the stress response to social isolation in sheep. Twenty adult Merino ewes were assigned to two groups; 1) Control group (CG, n = 10), which received an intranasal administration of isotonic saline and 2) Oxytocin-treated group (OTG, n = 10), which received an intranasal administration of OT (24 IU) 40 min before the animals were placed in the social isolation test. During the social isolation test (10 min), the behavior of the sheep was recorded, and blood samples were obtained before and after the test for the determination of cortisol, glucose and serum proteins, and heart rate and surface temperature were recorded. The OTG ewes had a higher cortisol concentration (P = 0.04) after social isolation, tended to vocalize more (P = 0.06) during isolation, and tended to have lower globulin concentrations (P = 0.10) than the CG ewes. Contrary to what we expected, the administration of intranasal OT increased the stress response to social isolation in ewes, which was evidenced by endocrine (greater increase in cortisol concentration), physiological (a tendency to present lower concentration of globulins in blood) and behavioral (a tendency to vocalize more) indicators. This study suggests that the administration of intranasal OT increased the stress response to isolation possibly by strengthening the social bond among ewes.

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 enhances the recovery of eye-contact induced autonomic arousal: A treatment mechanism study with placebo-controlled design

The neuropeptide oxytocin (OT) is suggested to exert a pivotal role in a variety of complex human behaviors, including trust, attachment, social perception and fear regulation. Previous studies have demonstrated that intranasal administration of OT reduces subjective and neuroendocrine stress responses and dampens amygdala reactivity. OT has also been proposed to modulate activity of the autonomic nervous system. Here, a randomized double-blind, placebo-controlled study (with parallel design) was conducted with 56 healthy adult men to investigate whether a single-dose of OT (24 IU) modulates sympathetic autonomic arousal upon live dyadic gaze interactions. To do so, electrodermal recordings of skin conductance were performed during the engagement of eye contact with a live model in a two-person social context. In accordance to prior research, direct eye gaze elicited a significant enhancement in skin conductance responses, but OT did not specifically enhance or dampen the overall magnitude (amplitude) of the skin conductance response. Administration of OT did facilitate the recovery of skin conductance responses back to baseline (reduced recovery time), indicating a role of OT in restoring homeostatic balance. Notably, the treatment-effect on autonomic recovery was most prominent in participants with low self-reported social responsiveness, indicating that person-dependent factors play an important role in determining OT treatment-responses. Exploratory, it was shown that OT also significantly reduced self-reported feelings of tension and (at trend-level) worrying about how one presents oneself. Together, these observations add further evidence to a role of OT in modulating activity of the autonomic nervous system, primarily by facilitating a restoration of homeostatic balance after stimulus-induced increases in sympathetically-driven autonomic arousal.

Intranasal oxytocin enhances approach-related EEG frontal alpha asymmetry during engagement of direct eye contact

The neuropeptide oxytocin is suggested to play a major role in a variety of complex human behaviours, including interpersonal bonding, trust and attachment. Recent theories have suggested that the role oxytocin plays in these complex social behaviours involves a modulation of motivational tendencies of approach-/avoidance-related behaviours. However, to date, direct neurophysiological evidence supporting this notion is limited. In this double-blind, randomized, placebo-controlled study with parallel design, we assessed the effects of administered intranasal oxytocin in 40 adult men on gaze behaviour and a neural marker of approach/avoidance motivational tendencies. Specifically, electroencephalography recordings were performed during the engagement of eye contact with a live model in a naturalistic two-person social context and electroencephalographic frontal alpha asymmetry, an established neurophysiological index of motivational tendencies for approach-/avoidance-related behaviours, was assessed. Compared to placebo, a single dose of oxytocin (24 international units) was shown to increase relative left-sided frontal asymmetry upon direct eye contact with a live model, which is indicative of an increase in approach-related motivational tendencies towards the presented eye contact stimulus. Notably, the treatment effect was most prominently observed in participants with lower self-reported social motivation (higher Motivation subscale scores on the Social Responsiveness Scale), indicating that participants with lower social motivation benefitted the most from the administered oxytocin. No treatment-specific changes were identified in terms of gaze behaviour towards the eye region of the live model. Together, these observations add neurophysiological evidence to the hypothesized role of oxytocin in modulating approach-/avoidance-related tendencies and suggest that inter-subject variability in person-dependent factors need to be considered to evaluate the potential benefit of intranasal oxytocin as a treatment. This notion is of particular relevance to the variety of neuropsychiatric populations such as autism spectrum disorder, social anxiety disorder and depression, for which intranasal oxytocin is increasingly considered a potential treatment.

Effects of Intranasal Oxytocin on Stress-Induced Cigarette Craving in Daily Smokers

BACKGROUND

Cigarette smoking is a well-known public health concern, and there is an urgent need to develop new treatments to reduce smoking or facilitate abstinence. One factor that is known to contribute to relapse is stress, making the stress response an important target for treatment. The neuropeptide oxytocin (OT) is believed to have stress-reducing effects, and in addition there is evidence that it reduces drug craving. The purpose of the present study was to examine the effects of intranasal OT on stress-induced cigarette craving in regular smokers after 12 h of abstinence.

METHOD

Daily smokers (n = 48) completed a stress induction task and a nonstressful control task at two different sessions, receiving intranasal OT (40 IU) or placebo (PBO) before or after the task. Subjects were randomly assigned to one of three groups: Group PP (n = 16) received PBO before and after the stress/control tasks, Group OP (n = 16) received OT before the tasks and PBO after, and Group PO (n = 16) received PBO before the tasks and OT shortly after completing the tasks. Cigarette craving as well as subjective and physiological responses to stress was assessed.

RESULTS

OT did not alter responses to stress, whether it was administered before or after the stressful task, on measures of cigarette craving, anxiety, heart rate, blood pressure, and cortisol levels.

CONCLUSIONS

The current study findings do not support several previous reports that OT reduced either stress or drug craving.

IMPLICATIONS

This study finds a null result of the neuropeptide oxytocin on stress-induced cigarette craving. Reporting null findings is part of the process of identifying potential treatments for addictive disorders.

The effect of oxytocin, gender, and ovarian hormones on stress reactivity in individuals with cocaine use disorder

RATIONALE

Cocaine use disorder (CUD) is associated with dysregulation of the hypothalamic-pituitary-adrenal axis, which plays a critical role in the human stress response. Men and women with CUD differ in reactivity to social stressors. The hypothalamic neuropeptide oxytocin is involved in anxiolytic and natural reward processes, and has shown therapeutic potential for addictive disorders and stress reduction.

OBJECTIVES

To examine the impact of oxytocin (oxytocin (OXY) vs. placebo (PBO)) and gender (female (F) vs. male (M)) on response to a social stress task in individuals with CUD. To explore whether ovarian hormones moderate this stress response.

METHODS

One hundred twelve adults with CUD were randomized to receive 40 IU intranasal oxytocin (n = 56) or matching placebo (n = 56). Forty minutes after drug administration, participants were exposed to a social stressor. Generalized linear mixed models were used to examine neuroendocrine (cortisol) and subjective (craving, stress) response at pre-stressor, stressor + 0, + 10, + 30, + 60 min.

RESULTS

Gender moderated the effect of oxytocin on neuroendocrine response (p = 0.048); women receiving oxytocin (F + OXY) showed blunted cortisol response compared to the other three groups (F + PBO; M + OXY; M + PBO). There was a main effect of gender on subjective stress response; women reported greater stress following the stressor compared to men (p = 0.016). Oxytocin had no significant effect on craving or stress, and gender did not moderate the effect of oxytocin on either measure. Higher endogenous progesterone was associated with lower craving response in women (p = 0.033).

CONCLUSIONS

Oxytocin may have differential effects in men and women with CUD. Women may be at greater risk for relapse in response to social stressors, but ovarian hormones may attenuate this effect.

Breastfeeding dynamically changes endogenous oxytocin levels and emotion recognition in mothers

Breastfeeding behaviours can significantly change mothers' physiological and psychological states. The hormone oxytocin may mediate breastfeeding and mothers' emotion recognition. This study examined the effects of endogenous oxytocin fluctuation via breastfeeding on emotion recognition in 51 primiparous mothers. Saliva oxytocin was assessed before and after the manipulation (breastfeeding or holding an infant), and emotion recognition tasks were conducted. Among mothers who breastfed daily, mothers with more increased levels of oxytocin after breastfeeding showed more reduced negative recognition and enhanced positive recognition of adult facial expressions. These oxytocin functions accompanying breastfeeding may support continued nurturing behaviours and also affect the general social cognition of other adults beyond any specific effect on infants.

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.

Kinetics of oxytocin effects on amygdala and striatal reactivity vary between women and men

Accumulating evidence suggests that intranasal oxytocin (OXT; 24 IU) reduces amygdala responses to fear-related stimuli in men, while exerting inverse effects in women. However, OXT enhances activity of the brain reward system in both sexes. Importantly, a crucial and still open question is whether there are sex-specific dose-response relationships for the amygdala and striatal regions. To address this question, a total of 90 healthy women participated in a double-blind, placebo-controlled crossover functional magnetic resonance imaging (fMRI) study and the results were compared with our previous findings from men. Participants were randomly assigned to three doses of OXT (6 IU, 12 IU, and 24 IU) and completed an emotional face recognition task including fearful and happy faces of varying emotional intensities. Across doses, OXT enhanced amygdala reactivity to low fearful faces compared to placebo and increased responses to happy faces in the dorsal striatum in women. While treatment effects on amygdala reactivity were evident at each given dose, the OXT effect on striatal responses to social stimuli was more pronounced with higher doses, but this dose-dependent effect did not survive correction for multiple comparisons. Importantly, OXT effects on amygdala and striatal activation significantly differed between sexes and striatal baseline sexual-dimorphic response patterns were diminished after administration of OXT. Our findings suggest that OXT increases the salience of social signals by strengthening the sensitivity for these signals in the amygdala and in the striatum in women, while OXT may primarily induce anxiolysis by reducing amygdala responses in men.

Serotonin mediates the panicolytic-like effect of oxytocin in the dorsal periaqueductal gray

INTRODUCTION AND OBJECTIVES

Oxytocin (OT) has been widely linked to positive social interactions, and there is great interest in OT as a therapy for a variety of neuropsychiatric conditions. Recent evidence also suggests that OT can play an important role in the mediation of anxiety-associated defensive responses, including a role for serotonin (5-HT) neurotransmission in this action. However, it is presently unknown whether OT additionally regulates the expression of panic-related behaviors, such as escape, by acting in the dorsal periaqueductal gray (dPAG), a key panic-regulating area. This study aimed to investigate the consequence of OT injection in the dPAG on escape expression and whether facilitation of 5-HT neurotransmission in this midbrain area is implicated in this action.

METHODS

Male Wistar rats were injected with OT in the dPAG and tested for escape expression in the elevated T-maze (ETM) and dPAG electrical stimulation tests. Using the latter test, OT's effect was also investigated after previous intra-dPAG injection of the OT receptor antagonist atosiban, the preferential antagonists of 5-HT_1A and 5-HT_2A receptors, WAY-100635 and ketanserin, respectively, or systemic pretreatment with the 5-HT synthesis inhibitor p-CPA.

RESULTS

OT impaired escape expression in the two tests used, suggesting a panicolytic-like effect. In the ETM, the peptide also facilitated inhibitory avoidance acquisition, indicating an anxiogenic effect. Previous administration of atosiban, WAY-100635, ketanserin, or p-CPA counteracted OT's anti-escape effect.

CONCLUSIONS

OT and 5-HT in the dPAG interact in the regulation of panic- and anxiety-related defensive responses. These findings open new perspectives for the development of novel therapeutic strategies for the treatment of anxiety disorders.

Effects of chronic intranasal oxytocin on behavior and cerebral glucose uptake in juvenile titi monkeys

Intranasal oxytocin (IN OXT) has been proposed as a treatment for autism spectrum disorder (ASD); however, little is known about the effects of long-term exposure. This is the first study in a non-human primate species to examine how developmental exposure to chronic IN OXT affects juvenile's interactions with family members, social preference for parents versus strangers, anxiety-like behavior, and cerebral glucose metabolism. Titi monkeys are socially monogamous and biparental; their family bonds share important characteristics with human family bonds. Fourteen males and 15 females were treated intranasally with saline (n = 14) or 0.8 IU/kg OXT (n = 15), daily from 12 to 18 months of age. Compared to SAL-treated animals, OXT-treated animals of both sexes spent significantly more time grooming other family members (F₁ = 8.97, p = 0.006). Overall, OXT-treated subjects were more social (F₁ = 8.35, p = 0.005) during preference tests. OXT-treated females displayed an enhanced preference for their parents (t = 2.265, p = 0.026). OXT-treated males had a blunted preference for their parents and an increase in the time spent near unfamiliar pairs (F1 = 10.89, p = 0.001). During anxiety tests, OXT-treated males refused to complete the task more often than SAL-treated males and had longer latencies (p < 0.0001). Neuroimaging studies revealed that OXT-treated animals had higher glucose uptake across the social salience network as a whole after one month of treatment (F_1,9 = 1.07, p = 0.042). Our results suggest moderate prosocial effects of chronic IN OXT, that did not depend on anxiolytic properties. We also found important sex differences that should be considered in a translational context.

The influence of gender and oxytocin on stress reactivity, cigarette craving, and smoking in a randomized, placebo-controlled laboratory relapse paradigm

RATIONALE

Female cigarette smokers tend to show greater cessation failure compared with males. Variables that contribute to the maintenance of smoking, including stress and craving, may differentially impact male and female smokers. Novel pharmacotherapies, such as oxytocin, may attenuate stress reactivity and craving in smokers, but work in this area is limited.

OBJECTIVES

This study assessed the influence of gender and oxytocin on stress reactivity, craving, and smoking in a randomized, placebo-controlled laboratory relapse paradigm.

METHODS

Male and female adult cigarette smokers (ages 18-45) were enrolled (women oversampled 2:1) and completed a laboratory session, in which intranasal oxytocin or placebo was administered followed by a laboratory social stress task. The role of gender and oxytocin were assessed on measures of stress reactivity, cigarette craving, latency to smoke in a resistance task, subjective responses to smoking, and ad-libitum smoking.

RESULTS

Participants (N = 144) had a mean age of 31 were 63% female and 56% White. Following stress induction, female smokers evidenced greater subjective stress than males, though males demonstrated greater neuroendocrine reactivity and smoking intensity than females. No gender differences were demonstrated for craving. Oxytocin did not attenuate any aspect of stress reactivity, craving, smoking, or subjective responses to smoking compared with placebo.

CONCLUSIONS

Gender differences in stress reactivity were shown in the hypothesized direction, but oxytocin appeared to exert little impact on subjective or behavioral metrics. Results highlight the complex relationship between gender, stress, and smoking, as well as the implications for oxytocin as a potential pharmacotherapy for smoking cessation.

The Role of the Oxytocin System in Anxiety Disorders

Oxytocin, a neuropeptide synthesized by the hypothalamus, plays a central role in human social behavior, social cognition, anxiety, mood, stress modulation, and fear learning and extinction. The relationships between oxytocin and psychiatric disorders including depression, anxiety, schizophrenia, and autism spectrum disorder have been extensively studied. In this chapter, we focus on the current knowledge about oxytocin and anxiety disorder. We discuss the anxiolytic effects of oxytocin in preclinical and clinical findings, possible related neurobehavioral mechanisms (social cognition, fear learning, and extinction), related neurotransmitter and neuroendocrine systems (hypothalamus-pituitary-adrenal axis, serotoninergic, and GABAergic systems), and studies regarding plasma levels of oxytocin, genetic and epigenetic findings, and effects of intranasal oxytocin in DSM-5 anxiety disorder (primarily social anxiety disorder and separation anxiety disorder) patients.

Intranasal oxytocin selectively modulates the behavior of rhesus monkeys in an expression matching task

Although the neuropeptide oxytocin (OT) is thought to regulate prosocial behavior in mammals, there is considerable debate as to how intranasal OT influences primate behavior. The aim of this study was to determine whether intranasal OT has a general anxiolytic effect on the performance of rhesus monkeys tasked with matching face stimuli, or a more selective effect on their behavior towards aversive facial expressions. To this end, we developed an innovative delayed match-to-sample task where the exact same trials could be used to assess either a monkey’s ability to match facial expressions or facial identities. If OT has a general affect on behavior, then performance in both tasks should be altered by the administration of OT. We tested four male rhesus monkeys (Macaca mulatta) in both the expression and identity task after the intranasal administration of either OT or saline in a within-subjects design. We found that OT inhalation selectively reduced a selection bias against negatively valenced expressions. Based on the same visual input, performance in the identity task was also unaffected by OT. This dissociation provides evidence that intranasal OT affects primate behavior under very particular circumstances, rather than acting as a general anxiolytic, in a highly translatable nonhuman model, the rhesus monkey.

Working Smarter Not Harder: Oxytocin Increases Domestic Dogs' (Canis familiaris) Accuracy, but Not Attempts, on an Object Choice Task

The neuropeptide oxytocin (OT) has been shown to enhance dogs' ability to perform an object choice task (OCT) involving the use of human pointing cues, when delivered intranasally. This study aimed at further investigating whether OT enhances task performance by increasing choices made, or by increasing correctness of choices made, and to compare these treatment effects to dog appeasing pheromone (DAP), known to balance emotional activation in dogs. Hence, we compared OCT performance between three groups of dogs: (i) dogs administered OT and a sham collar, (ii) dogs administered a saline placebo and a DAP collar, and (iii) control dogs administered a saline placebo and a sham collar. All three groups consisted of a combination of male and female pet dogs and assistance-dogs-in-training currently living with a volunteer carer. The study also evaluated the effect of intranasal OT and/or DAP on plasma levels of OT, and prolactin; which has previously been linked with anxiety in dogs. The dogs' emotional state was measured using the Emotional Disorders Evaluation in Dogs (EDED) scale. The owners'/carers' degree of anxious- and avoidant-style attachment to their dogs was accessed using the Pet Attachment Questionnaire (PAQ). Interesting descriptive data appeared for both treatment groups. Particularly, in OT group, we obtained significant results demonstrating that intranasal OT enhances OCT performance in dogs compared to control, by increasing the percentage of correct choices, but not the number of choices, made. Results also support that the mode of action of intranasal OT is via direct access to the brain and not via the blood, since no elevation of plasma OT (or prolactin) levels were observed after intranasal administration in this study. Similarly, DAP application did not significantly alter OT or prolactin peripheral concentrations. Several differences were observed between fostered and pet dogs, namely: fostered dogs demonstrated higher levels of serum prolactin, made more choices on the OCT compared to pet dogs but were not more likely to be correct, and were fostered by carers with higher avoidant attachment scores than pet dog owners. These findings implicate consideration of potential carer and training consequences for assistance dogs.

Psychological effects of breastfeeding on children and mothers

While the nutritional and physical health benefits of breastfeeding are well established, accumulating research demonstrates the far-reaching psychological effects of breastfeeding on children and their mothers. Here, we provide a non-exhaustive review of the empirical evidence, showing that breastfeeding impacts children's brain, cognitive, and socio-emotional development. In mothers, research is presented indicating that breastfeeding influences mood, affect, stress, and maternal care. The current review aims to provide a broad overview of existing findings on the psychological effects of breastfeeding, highlighting the important role that breastfeeding plays across several dimensions of psychological functioning. We also discuss the potential mechanisms that may underpin the observed effects, provide a constructive commentary on the limitations of the existing work, and put forth some considerations when evaluating this line of research.

DNA methylation of OXTR is associated with parasympathetic nervous system activity and amygdala morphology

Oxytocin has anxiolytic properties whose mechanisms of action are still being identified. DNA methylation in the promoter region of the oxytocin receptor gene (OXTR), an epigenetic modification that putatively reflects a downtuning of the oxytocin system, has previously been implicated in the regulation of fear-related responses through the amygdala. In this study, we attempted to characterize the relationship between methylation of OXTR and anxiogenesis using two distinct endophenotypes: autonomic nervous system activity and subcortical brain structure. In 79 participants, we found that increased OXTR methylation is associated with attenuated resting parasympathetic tone, measured using high-frequency heart rate variability. Further, we found that this relationship is mediated by brain morphology, such that OXTR methylation is associated with increased gray matter of the central amygdala which is, in turn, associated with decreased parasympathetic tone. These results further our understanding of epigenetic regulation of the human oxytocin system and its role in anxiogenesis.

Effect of intranasal oxytocin on alcohol withdrawal syndrome: A randomized placebo-controlled double-blind clinical trial

BACKGROUND

In a pilot study, intranasal oxytocin was demonstrated to reduce the benzodiazepine dose needed to relieve withdrawal symptoms during alcohol detoxification. The aim of the present study was to compare the effect of oxytocin and placebo during a three-day period of alcohol detoxification at an addiction treatment center in Norway.

METHODS

Randomized, double-blind, placebo-controlled trial with 40 patients fulfilling criteria for ICD-10 diagnosis of alcohol dependence (F10.2), admitted for alcohol detoxification and withdrawal treatment. The benzodiazepine oxazepam was given as symptom-triggered treatment based on the scores of the Clinical Institute Withdrawal Assessment for Alcohol revised (CIWA-Ar) scale. Participants were randomized to receive either intranasal oxytocin (24 IU twice daily) or placebo.

PRIMARY OUTCOME

Oxazepam dose required to complete a three-day course of detoxification.

SECONDARY OUTCOMES

Scores of the CIWA-Ar, the 10-item Hopkins Symptom Check List (HSCL-10), and self-reported total number of hours of sleep.

RESULTS

The mean total oxazepam dose (± standard deviation) was 56.8 ± 72.8 mg in the oxytocin group and 79.0 ± 122.9 in the placebo group (p = 0.490; difference -22.3 mg; 95% confidence interval (CI) -86.9 to +42.4 mg). The findings were inconclusive as to whether a difference in the CIWA-Ar score (5.94 ± 3.86 vs. 6.48 ± 3.92; p = 0.665) or in any of the other secondary outcomes was present. No serious adverse events were reported.

CONCLUSION

Compared to placebo, intranasal oxytocin did not significantly reduce the oxazepam dose needed to complete a 3-day course of alcohol detoxification and withdrawal treatment.

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.

Sex differences in stress reactivity after intranasal oxytocin in recreational cannabis users

Cannabis is the most widely used illicit drugs and the changing legal, political and cultural climate will likely increase cannabis use further. One factor that may underlie the transition from recreational use to problematic use is stress. The hormone oxytocin (OXT) modulates stress and may have therapeutic efficacy for substance use disorders, but few studies have examined OXT in cannabis users. Another factor is sex; although more men smoke cannabis, the transition from recreational to problematic use is faster in women. Using a within-subjects design, the effects of intranasal (i.n.) oxytocin (OXT; 40 IU) administration on stress reactivity (using the Trier Social Stress Test; TSST) and cannabis (5.6% THC) self-administration was assessed in recreational cannabis using men (n = 31) and women (n = 32) relative to i.n. placebo (PBO) and no-stress (NST) conditions. The TSST produced expected subjective and cardiovascular effects compared to the NST. However, in the i.n. OXT-TSST condition, positive subjective effects were lower and negative subjective effects were higher in women compared to PBO administration and compared to men. Further, latency to self-administer cannabis was longer in women than men and women self-administered less cannabis than men regardless of stress condition. There were no differences in cannabis craving as a function of sex, stress, or medication. These results suggest that OXT administration may lead to greater stress reactivity in recreational cannabis users, particularly women, and support growing evidence that sex differences should be carefully considered when examining the therapeutic potential of OXT.

Oxytocin facilitates adaptive fear and attenuates anxiety responses in animal models and human studies-potential interaction with the corticotropin-releasing factor (CRF) system in the bed nucleus of the stria terminalis (BNST)

Despite its relatively well-understood role as a reproductive and pro-social peptide, oxytocin (OT) tells a more convoluted story in terms of its modulation of fear and anxiety. This nuanced story has been obscured by a great deal of research into the therapeutic applications of exogenous OT, driving more than 400 ongoing clinical trials. Drawing from animal models and human studies, we review the complex evidence concerning OT's role in fear learning and anxiety, clarifying the existing confusion about modulation of fear versus anxiety. We discuss animal models and human studies demonstrating the prevailing role of OT in strengthening fear memory to a discrete signal or cue, which allows accurate and rapid threat detection that facilitates survival. We also review ostensibly contrasting behavioral studies that nonetheless provide compelling evidence of OT attenuating sustained contextual fear and anxiety-like behavior, arguing that these OT effects on the modulation of fear vs. anxiety are not mutually exclusive. To disambiguate how endogenous OT modulates fear and anxiety, an understudied area compared to exogenous OT, we survey behavioral studies utilizing OT receptor (OTR) antagonists. Based on emerging evidence about the role of OTR in rat dorsolateral bed nucleus of stria terminalis (BNST) and elsewhere, we postulate that OT plays a critical role in facilitating accurate discrimination between stimuli representing threat and safety. Supported by human studies, we demonstrate that OT uniquely facilitates adaptive fear but reduces maladaptive anxiety. Last, we explore the limited literature on endogenous OT and its interaction with corticotropin-releasing factor (CRF) with a special emphasis on the dorsolateral BNST, which may hold the key to the neurobiology of phasic fear and sustained anxiety.

The Oxytocin Receptor: From Intracellular Signaling to Behavior

The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1 , as listed in PubMed), which revealed central roles for OXT and its receptor (OXTR) in reproduction, and social and emotional behaviors in animal and human studies focusing on mental and physical health and disease. In this review, we discuss the mechanisms of OXT expression and release, expression and binding of the OXTR in brain and periphery, OXTR-coupled signaling cascades, and their involvement in behavioral outcomes to assemble a comprehensive picture of the central and peripheral OXT system. Traditionally known for its role in milk let-down and uterine contraction during labor, OXT also has implications in physiological, and also behavioral, aspects of reproduction, such as sexual and maternal behaviors and pair bonding, but also anxiety, trust, sociability, food intake, or even drug abuse. The many facets of OXT are, on a molecular basis, brought about by a single receptor. The OXTR, a 7-transmembrane G protein-coupled receptor capable of binding to either Gαior Gαqproteins, activates a set of signaling cascades, such as the MAPK, PKC, PLC, or CaMK pathways, which converge on transcription factors like CREB or MEF-2. The cellular response to OXT includes regulation of neurite outgrowth, cellular viability, and increased survival. OXTergic projections in the brain represent anxiety and stress-regulating circuits connecting the paraventricular nucleus of the hypothalamus, amygdala, bed nucleus of the stria terminalis, or the medial prefrontal cortex. Which OXT-induced patterns finally alter the behavior of an animal or a human being is still poorly understood, and studying those OXTR-coupled signaling cascades is one initial step toward a better understanding of the molecular background of those behavioral effects.

Intranasal oxytocin dampens cue-elicited cigarette craving in daily smokers: a pilot study

Despite moderate success with pharmacological and behavioral treatments, smoking relapse rates remain high, and many smokers report that smoking cues lead to relapse. Therefore, treatments that target cue reactivity are needed. One candidate for reducing craving is the neuropeptide oxytocin (OT). Here, we investigated the effects of intranasal OT on two types of craving for cigarettes: craving following overnight abstinence and craving elicited by smoking-related cues. In this within-subject, placebo-controlled pilot study, smokers (N=17) abstained from smoking for 12 h before attending two sessions randomized to intranasal OT or placebo (i.e. saline nasal spray). On each session, participants received two doses of OT (20 IU) or placebo at 1-h intervals, and rated craving before and after each dose. Spontaneous cigarette craving was assessed after the first spray, and cue-elicited craving was assessed following the second spray. OT did not reduce levels of spontaneous craving after the first spray, but significantly dampened cue-induced smoking craving. These results provide preliminary evidence that OT can reduce cue-induced smoking craving in smokers. These findings provide an important link between preclinical and clinical studies aimed at examining the effectiveness of OT as a novel treatment for drug craving.

Oxytocin for the treatment of drug and alcohol use disorders

There is growing interest in the use of oxytocin (OT) as a potential treatment for alcohol and other substance-use disorders. OT is a neuropeptide that modulates adaptive processes associated with addiction including reward, tolerance, associative learning, memory, and stress responses. OT exerts its effects through interactions with the hypothalamic-pituitary-adrenal axis and multiple neurotransmitter systems including the dopamine mesolimbic reward and corticotrophin-releasing factor stress systems. The effects of OT on stress systems are of high interest, given the strong link between stress, drug use and relapse, and known dysregulation of hypothalamic-pituitary-adrenal-axis activity associated with substance-use disorders. At the same time, the OT system is itself altered by acute or chronic drug exposure. This review summarizes the preclinical and clinical literature on the OT system and its relevance to drug and alcohol addiction. In addition, findings from recent clinical trials conducted in participants with cocaine, cannabis, or alcohol use disorder are included and evidence that OT may help to normalize blunted stress responses, and attenuate withdrawal-associated hypercortisolism, negative mood, and withdrawal symptoms is summarized.

Kinetics and Dose Dependency of Intranasal Oxytocin Effects on Amygdala Reactivity

BACKGROUND

Current neuroimaging perspectives on a variety of mental disorders emphasize dysfunction of the amygdala. The neuropeptide oxytocin (OXT), a key mediator in the regulation of social cognition and behavior, accumulates in cerebrospinal fluid after intranasal administration in macaques and humans and modulates amygdala reactivity in both species. However, the translation of neuromodulatory OXT effects to novel treatment approaches is hampered by the absence of studies defining the most effective dose and dose-response latency for targeting the amygdala.

METHODS

To address this highly relevant issue, a total of 116 healthy men underwent functional magnetic resonance imaging using a randomized, double-blind, placebo-controlled crossover study design. The experimental rationale was to systematically vary dose-test latencies (15-40, 45-70, and 75-100 minutes) and doses of OXT (12, 24, and 48 international units) in order to identify the most robust effects on amygdala reactivity. During functional magnetic resonance imaging, subjects completed an emotional face recognition task including stimuli with varying intensities ranging from low (highly ambiguous) to high (less ambiguous).

RESULTS

Our results indicate that the OXT-induced inhibition of amygdala responses to fear was most effective in a time window between 45 and 70 minutes after administration of a dose of 24 international units. Furthermore, the observed effect was most evident in subjects scoring high on measures of autistic-like traits. Behavioral response patterns suggest that OXT specifically reduced an emotional bias in the perception of ambiguous faces.

CONCLUSIONS

These findings provide initial evidence of the most effective dose and dose-test interval for future experimental or therapeutic regimens aimed at targeting amygdala functioning using intranasal OXT administration.

The Role of Endogenous Oxytocin in Anxiolysis: Structural and Functional Correlates

BACKGROUND

Oxytocin is anxiolytic, and administration of synthetic oxytocin in humans reduces amygdala reactivity to negative stimuli. However, it is unknown whether endogenous oxytocin levels-which are heritable and stable across time-attenuate anxiety via similar mechanisms.

METHODS

In this study, we used plasma assays and structural and functional neuroimaging to examine potential anxiolytic effects of endogenous oxytocin in 73 participants.

RESULTS

We found that higher endogenous oxytocin levels are associated with reduced central amygdala volume and blood oxygen level-dependent activity in response to aversive stimuli. In contrast to previous reports, we found that oxytocin was not related to patterns of functional connectivity between the amygdala and other brain regions.

CONCLUSIONS

Together, our results underscore the importance of considering individual differences in participants' endogenous oxytocin with respect to anxiety-related neural activity and neuromorphology.

Oxytocin and Anxiety Disorders: Translational and Therapeutic Aspects

PURPOSE OF REVIEW

This review aims to evaluate the most recent literature examining the oxytocin (OXT) system's role in human anxiety by surveying various fields of preclinical and clinical research supporting this role, and queries whether the OXT system might be a target for novel anxiolytics.

RECENT FINDINGS

Evidence from the diverse body of literature presented here, from translational research, genetic and neuroimaging studies, to clinical trials of intranasal (IN) OXT reveals a positive association. In addition, some moderators (e.g., sex, specificities to cues) of OXT's anxiolytic effects can have an important influence on its outcomes, awaiting further research. Evidence for the role of OXT in regulating anxiety is undeniable. We expect that the diverse particularities of the OXT system will help broaden our understanding of anxiety and stress-related disorders. We conclude that OXT promises an enticing treatment option for human anxiety disorders especially those associated with socio-emotional dysfunctions.

The calming effect of a new wearable device during the anticipation of public speech

We assessed the calming effect of doppel, a wearable device that delivers heartbeat-like tactile stimulation on the wrist. We tested whether the use of doppel would have a calming effect on physiological arousal and subjective reports of state anxiety during the anticipation of public speech, a validated experimental task that is known to induce anxiety. Two groups of participants were tested in a single-blind design. Both groups wore the device on their wrist during the anticipation of public speech, and were given the cover story that the device was measuring blood pressure. For only one group, the device was turned on and delivered a slow heartbeat-like vibration. Participants in the doppel active condition displayed lower increases in skin conductance responses relative to baseline and reported lower anxiety levels compared to the control group. Therefore, the presence, as opposed to its absence, of a slow rhythm, which in the present study was instantiated as an auxiliary slow heartbeat delivered through doppel, had a significant calming effect on physiological arousal and subjective experience during a socially stressful situation. This finding is discussed in relation to past research on responses and entrainment to rhythms, and their effects on arousal and mood.

Effect of oxytocin pretreatment on cannabis outcomes in a brief motivational intervention

Motivational enhancement therapy (MET) is efficacious in reducing cannabis use, yet benefits are generally short-lived. Oxytocin is a hypothalamic neuropeptide that promotes prosocial behaviors and plays a role in drug-related neuroadaptations; as such, oxytocin may enhance the effect of MET on cannabis outcomes. Cannabis dependent adults were randomized to receive MET plus oxytocin (n =8) or placebo (n =8). Participants receiving oxytocin showed reductions in amount of cannabis used daily and number of sessions per day. Participants receiving placebo did not evidence significant reductions. Powered clinical trials of oxytocin-enhanced MET for cannabis use disorder are warranted.

Oxytocin response to youth-mother interactions in clinically anxious youth is associated with separation anxiety and dyadic behavior

BACKGROUND

Anxiety disorders are common in youth and cause significant distress and impairment to the individual and family. Oxytocin (OT), a nine amino acid peptide, is implicated in anxiety regulation and modulation of close interpersonal and attachment behavior. Anxiety disorders have been linked to low levels of salivary OT in youth. Research has also linked oxytocinergic functioning to social support, warm contact, and bonding, and indicated that contact with attachment figures stimulates OT response. We examined OT response to a brief, positive youth-mother interaction in clinically anxious youth. We investigated whether quality of the youth-mother interaction as well as the presence of particular anxiety disorders, are associated with youth OT response.

METHOD

Salivary OT from 41 youth with primary DSM-5 anxiety disorders was assayed before and after a 7-min youth-mother interaction that was later systematically coded by two reliable coders. Youth and mothers also completed rating scales of youth anxiety symptoms.

RESULTS

Affective touch, maternal sensitivity, maternal intrusiveness, youth engagement, and youth initiative all contributed significantly to predicting youth OT response. Repeated measures analyses showed that when affective touch was high youth had greater OT response. OT response was positively associated with the presence of separation anxiety disorder (SAD) and with child ratings of separation anxiety.

CONCLUSIONS

The findings highlight the importance of maternal and dyadic behavior patterns to oxytocinergic response in clinically anxious youth, shed light on the association between OT and SAD, and point to possible intervention strategies.