Peripheral Oxytocin and Touch

Study Overview
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Brief Summary
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Research shows that slow gentle skin stroking can activate special sensory nerves in the skin that elicit relaxing effects on the body and mind, similar to the effects of the hormone oxytocin. Studies also suggest that gentle stroking may even release oxytocin in the skin. However, we do not know what oxytocin does in the skin and how it affects nerves that send pleasant touch or pain signals to the brain. The proposed study will determine how individuals perceive gentle stroking and experimental pain before and after a skin injection of oxytocin compared to a placebo injection.

Official Title
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Effect of Peripheral Oxytocin on Touch Pleasantness and Pain

Conditions
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Healthy Adults

Intervention / Treatment
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* Drug: Pitocin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Between the ages of 18 and 65 years old Fluent in English Healthy Exclusion Criteria: Sensory or motor nerve deficit Acute or chronic pain Major medical conditions such as kidney, liver, cardiovascular (hypertension, preexisting cardiac arrhythmia), autonomic, pulmonary, or neurological problems (e.g., seizure disorder) or a chronic systemic disease (e.g., diabetes). Any disease, diagnosis, or condition (medical or surgical) that, in the opinion of the Principal Investigator, would place the subject at increased risk (active gynecologic disease in which increased tone would be detrimental e.g., uterine fibroids with ongoing bleeding), compromise the subject's compliance with study procedures, or compromise the quality of the data Unstable psychiatric conditions Needle phobia or history of fainting Current use of opiate medication(s) Hypersensitivity, allergy, or significant reaction to any ingredient of Pitocin® Currently pregnant or pregnant within the last two years Currently nursing or lactating Current or history of ventricular tachycardia, atrial fibrillation or prolonged QT interval Past or current history of hyponatremia or at risk for hyponatremia Current use of thiazide diuretics, loop diuretics, combination diuretics, lithium, carbamazepine, enalapril, Ramipril, celecoxib, temazepam, gliclazide, glimepiride, glibenclamide, glipizide, omeprazole, pantoprazole, desmopressin, selective serotonin reuptake inhibitors, monoamine oxidase inhibitora, or the recreational drug ecstasy Latex allergy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Order 1<br>Participants will receive 4mcg/2ml oxytocin during Session 1 and 2ml isotonic saline during Session 2, injected into the forearm. | Drug: Pitocin<br>* At each session, 4mcg/2ml oxytocin or 2ml isotonic saline (0.9% sodium chloride; placebo control) will be injected into the middle of the dorsal forearm. Sessions will be separated by at least 48 hours to ensure drug clearance.<br>|
| Experimental: Order 2<br>Participants will receive 2ml isotonic saline during Session 1 and 4mcg/2ml oxytocin during Session 2, injected into the forearm. | Drug: Pitocin<br>* At each session, 4mcg/2ml oxytocin or 2ml isotonic saline (0.9% sodium chloride; placebo control) will be injected into the middle of the dorsal forearm. Sessions will be separated by at least 48 hours to ensure drug clearance.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in mean pleasantness rating of gentle brushing | Touch pleasant/unpleasantness ratings will be assessed in response to slow gentle brushing using a Visual Analog Scale with anchors of Extremely unpleasant to Neutral to Extremely pleasant. Change in mean rating of slow brushing will be compared between the oxytocin and placebo sessions. | Day 1 and Day 2 | 
| Change in mechanical threshold | Change in first percept of sharpness using standard set of weighted pinprick stimuli will be compared between the oxytocin and placebo sessions. | Day 1 and Day 2 | 
| Change in temporal summation of pinprick stimuli | Temporal summation will be tested using a standard 256 milliNewtons (mN) pinprick stimulus applied for 10 repetitions. The participant will provide pain ratings for a single pinprick and for the 10 repetitions, using a Visual Analog Scale rating scale with anchors No pain to Most intense pain imaginable. This procedure will be repeated 5 times and the mean pain rating used. Change in mean rating will be compared between the oxytocin and placebo sessions. | Day 1 and Day 2 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pressure pain threshold | Pressure pain threshold will be tested using a pressure algometer placed over the dorsal forearm muscles, and pressure will be increased until pain is reported. | Day 1 and Day 2 | 
| Heat pain threshold | Heat pain threshold (HPT) will be tested using a high-quality thermode. To establish HPT, the thermode will be placed on the arm at a baseline temperature of 32 Celsius and will be increased until the stimulus is reported as painful by the participant. The mean of three trials will be taken as the HPT. | Day 1 and Day 2 | 
| Heat pain ratings | Three 10s trials of the individually calibrated heat stimulus rated 70/100 will be rated using using a Visual Analog Scale rating scale with anchors No pain to Most intense pain imaginable. | Day 1 and Day 2 | 
| Anxiety using the State-Trait Anxiety Inventory | The investigators will measure anxiety levels using the State-Trait Anxiety Inventory. This measure will be included in a linear regression model to determine whether this measure significantly predicts effects of oxytocin on touch perception. | Day 1 | 
| Pain Anxiety using the Pain Anxiety Symptoms Scale short form | The investigators will measure pain anxiety levels using the Pain Anxiety Symptoms Scale short form. This measure will be included in a linear regression model to determine whether this measure significantly predicts effects of oxytocin on touch perception. | Day 1 | 
| Interoceptive Sensibility using the Multidimensional Assessment of Interoceptive Awareness | The investigators will measure interoceptive sensibility using the Multidimensional Assessment of Interoceptive Awareness. This measure will be included in a linear regression model to determine whether this measure significantly predicts effects of oxytocin on touch perception. | Day 1 | 
| Attention to body using the The Body Awareness Questionnaire | The investigators will measure attention to the body using the The Body Awareness Questionnaire. This measure will be included in a linear regression model to determine whether this measure significantly predicts effects of oxytocin on touch perception. | Day 1 | 
| Autistic traits using the Autism Quotient | The investigators will measure autistic traits using the Autism Quotient. This measure will be included in a linear regression model to determine whether this measure significantly predicts effects of oxytocin on touch perception. | Day 1 | 
| Mood using the Profile of Mood States Questionnaire | The investigators will measure mood using the Profile of Mood States Questionnaire. This measure will be included in a linear regression model to determine whether this measure significantly predicts effects of oxytocin on touch perception. | Day 1 |