The Interaction Between Oxytocin and Serotonin

Study Overview
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Brief Summary
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The primary objective of this study is to identify any interaction between oxytocin and serotonin on neural and behavioral activity related to social reward and decision making by a double-blind, placebo-controlled, between-subject, pharmacological fMRI design

Detailed Description
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Serotonin and oxytocin have been proved to play an important role in social reward processing and decision making in human. The aim of this study is to determine whether they interact in those essential human behaviors by a double-blind, placebo-controlled, between-subject, pharmacological fMRI design, in which 4 groups of healthy males will be administered with a random combination of nasal oxytocin (24 international units, IU) or placebo and acute tryptophan depletion (ATD, 75.2g) or placebo (a tryptophan-balanced mixture, 78.2g). The social-reward related neural activity and behavior will be assessed by a series of social reward task in and out of fMRI scanner and the decision making will be assessed by reversal learning task, ultimatum game (UG) and loss aversion task. The interaction between serotonin and oxytocin on brain networks will also be tested by resting state.

Official Title
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The Interaction Between Oxytocin and Serotonin on the Social-reward Brain Networks and Decision Making

Conditions
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Healthy

Intervention / Treatment
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* Drug: oxytocin nasal spray
* Drug: ATD treatment
* Drug: intranasal placebo treatment (placebo-control for oxytocin)
* Drug: oral placebo treatment (placebo-control for ATD)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy subjects without past or current psychiatric or neurological disorders Right-handedness Exclusion Criteria: History of head injury; Medical or psychiatric illness. High blood pressure, general cardio-vascular alterations History of drug or alcohol abuse or addiction. Allergy against medications or general strong allergies Sleep disorders. Visual or motor impairments

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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Male

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: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: male oxytocin and ATD group<br>male subjects receiving oxytocin and ATD treatment | Drug: oxytocin nasal spray<br>* intranasal administration of oxytocin (24 IU)<br>Drug: ATD treatment<br>* oral administration of ATD (75.2g) (Acute Tryptophan Depletion)<br>|
| Experimental: male oxytocin and placebo group<br>male subjects receiving oxytocin and ATD-placebo treatment | Drug: oxytocin nasal spray<br>* intranasal administration of oxytocin (24 IU)<br>Drug: oral placebo treatment (placebo-control for ATD)<br>* oral administration of a tryptophan-balanced mixture (78.2g)<br>|
| Experimental: male placebo and ATD group<br>male subjects receiving oxytocin placebo and ATD treatment | Drug: ATD treatment<br>* oral administration of ATD (75.2g) (Acute Tryptophan Depletion)<br>Drug: intranasal placebo treatment (placebo-control for oxytocin)<br>* intranasal administration of placebo nasal spray<br>|
| Placebo Comparator: male placebo group<br>male subjects receiving oxytocin placebo and ATD placebo treatment | Drug: intranasal placebo treatment (placebo-control for oxytocin)<br>* intranasal administration of placebo nasal spray<br>Drug: oral placebo treatment (placebo-control for ATD)<br>* oral administration of a tryptophan-balanced mixture (78.2g)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in brain neural activity during the social reward processing as assessed via fMRI | Whole brain and region of interest (ROI) regression analysis will be used to compare the neural activity of participants in response to social reward task in different treatment groups. | approximately 45 minutes after intranasal administration of oxytocin, or placebo, approximately 5.5h after administration of ATD, or placebo | 
| Changes in the resting state as assessed via fMRI | Resting state activity in the social reward related and decision making brain networks will be compared between the treatment groups | Time Frame: approximately 45 minutes after intranasal administration of oxytocin, or placebo, approximately 5.5h after administration of ATD, or placebo | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Associations with Personalities of subjects | Personalities of subjects will be measured by a series of scales related to decision making and social reward, such as the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), which measures participants' sensitivity to reward and punishment. SPSRQ is a self-reported instrument that includes 48 yes/no questions divided into two subscales: Sensitivity to Reward (SR, 24 items, ranging from 0 (insensitive) to 24 (sensitive) to reward) and Sensitivity to Punishment (SP, 24 items, ranging from 0 (insensitive) to 24 (sensitive) to punishment). Associations between individual differences in personalities of subjects and differences in behaviors will be measured. | before 30mins ATD or placebo administration | 
| Behavioral performance in decision making task | Behavioral performance in reversal learning task will be measured and compared between treatment groups. | approximately 4h after administration of ATD, or placebo, before nasal spray | 
| Behavioral performance in social reward related task | Behavioral performance will be measured and compared between treatment groups | approximately 105 minutes after intranasal administration of oxytocin, or placebo, approximately 6.5h after administration of ATD, or placebo | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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social reward, decision making, oxytocin, serotonin