Peripheral Oxytocin and Touch

University of California, San Diego20 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

QUADRUPLE

Enrollment

Conditions

Healthy Adults

Interventions

PitocinDRUG

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.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: 1. Between the ages of 18 and 65 years old 2. Fluent in English 3. Healthy Exclusion Criteria: 4. Sensory or motor nerve deficit 5. Acute or chronic pain 6. 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). 7. 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 8. Unstable psychiatric conditions 9. Needle phobia or history of fainting 10. Current use of opiate medication(s) 11. Hypersensitivity, allergy, or significant reaction to any ingredient of Pitocin® 12. Currently pregnant or pregnant within the last two years 13. Currently nursing or lactating 14. Current or history of ventricular tachycardia, atrial fibrillation or prolonged QT interval 15. Past or current history of hyponatremia or at risk for hyponatremia 16. 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 17. Latex allergy

Locations (1)

ACTRI

La Jolla, California, United States

Outcomes

Primary Outcomes

Change in Mean Pleasantness Rating of Gentle Brushing

Touch pleasant/unpleasantness ratings will be assessed in response to slow gentle brushing using a "Pleasantness/Unpleasantness" Visual Analog Scale with anchors of "Extremely unpleasant" (coded -100) to "Neutral" to "Extremely pleasant (coded 100)." Change in mean rating of slow brushing will be compared between the oxytocin and placebo sessions. Higher values indicate increased pleasantness (better outcome).

Time frame: Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)

Change in Mechanical Threshold

"Mechanical threshold" task. Change in first reported percept of sharpness from application of a standard set of weighted pinprick stimuli (minimum 8mN; maximum 512 mN) will be compared between the oxytocin and placebo sessions. An increased threshold indicates reduced sensitivity to mechanical pain.

Time frame: Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)

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 for the repeated pinprick will be divided by the mean rating of the single pinprick to obtain the standard temporal summation ratio. Change in ratio will be compared between the oxytocin and placebo sessions.

Time frame: Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)

Secondary Outcomes

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. When pain is reported, the pressure level (in pounds of force) is recorded as the outcome measure.

Data from ClinicalTrials.gov

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