Oxytocin and the Processing of Social Stress-Associated Chemosignals

Study Overview
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Brief Summary
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The purpose of this study is to determine whether oxytocin modulates the processing of stress-associated chemosignals and which substrates are involved.

Detailed Description
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Social transmission of stress and fear is not restricted to visual or auditory cues, but extends to the olfactory domain, a phylogenetically more ancient sense. Exposure to axillary sweat from healthy volunteers undergoing an emotional stressor task evokes a strong vicarious stress response on the behavioral and neural level.Particularly, anxious individuals have been shown to exhibit a heightened sensitivity to social chemosensory stress cues (axillary sweat). The neuropeptide oxytocin (OXT) exerts anxiolytic and anti-stress effects in visual and auditory modalities, however, it still elusive whether OXT also modulates the processing of stress-associated chemosignals. Axillary sweat were obtained from an unrelated sample of 30 healthy men undergoing the Trier Social Stress Test and ergometer training as control.Subsequently, subjects completed a forced-choice emotional face recognition task composed of stimuli with varying intensities (neutral to fearful), while they were exposed to both sweat stimuli and a non-social control odor (raspberry) after OXT or placebo administration, respectively. The investigators expect that OXT selectively diminishes chemosensory-induced behavioral biases and neural responses to stress-related odors.

Official Title
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Double-blind, Placebo-controlled, Randomized Study: Oxytocin Modulation of Stress-Associated Chemosignals Processing

Conditions
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Healthy Volunteers

Intervention / Treatment
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* Drug: Oxytocin
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteers Right-handed Exclusion Criteria: Current or past psychiatric disease Current or past physical illness Psychoactive medication Tobacco smokers MRI contraindications (e.g. metal in body, claustrophobia) Anosmia Medication known to interfere with olfactory processing

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Oxytocin<br>40 IU Oxytocin, intranasal application 30 min prior to the experiment | Drug: Oxytocin<br>* 40 IU; 5 puffs balanced across nostrils, at an inter-puff interval of 30 seconds<br>* Other names: Syntocinon-Spray, Novartis;|
| Placebo Comparator: Placebo<br>sodium chloride solution, intranasal application 30 min prior to the experiment | Drug: Placebo<br>* Placebo nasal spray, 5 puffs balanced across nostrils, at an inter-puff interval of 30 seconds<br>* Other names: Placebo-Spray, Novartis;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Forced-choice ratings of morphed emotional faces with varying intensities (neutral to fearful). | After each trial, subjects were asked to use a button response grip to indicate whether they perceived the depicted face as neutral or fearful. | 30 min after nasal spray administration | 
| Response time for facial stimuli ratings. |  | 30 min after nasal spray administration | 
| Blood-oxygen-level dependent signal in response to chemosensory cues. | The modulatory effect of oxytocin on neural correlates Using functional magnetic resonance imaging, signal changes in the amygdala, hippocampus and the anterior cingulate cortex in response to olfactory cues of stress and sport (axillary sweat obtained from an unrelated sample of 30 healthy men undergoing the Trier Social Stress Test and ergometer training as control). | 30 minutes after nasal spray administration | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Questionnaire measurement of mood (PANAS). |  | 15 minutes before the nasal spray administration and (on average) 10 minutes after the fMRI experiment | 
| Saliva oxytocin concentrations |  | immediately before the nasal spray administration and (on average) 10 minutes after the fMRI experiment | 
| Questionnaire measurement of anxiety (STAI). |  | 15 minutes after nasal spray administration and (on average) 10 minutes after the fMRI experiment |