Peripheral Oxytocin and Touch (POPP)

Effect of Peripheral Oxytocin on Touch Pleasantness and Pain

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 Overview

• Status: Completed
• Conditions: Healthy Adults
• Intervention / Treatment: Drug: Pitocin

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • California
    • La Jolla, California, United States, 92115
      • ACTRI

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Order 1; Participants will receive 4mcg/2ml oxytocin during Session 1 and 2ml isotonic saline during Session 2, injected into the forearm.	Drug: Pitocin; 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.
Experimental: Order 2; Participants will receive 2ml isotonic saline during Session 1 and 4mcg/2ml oxytocin during Session 2, injected into the forearm.	Drug: Pitocin; 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.

What is the study measuring?

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

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. When pain is reported, the pressure level (in pounds of force) is recorded as the outcome measure.	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)
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.	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)
Heat Pain Ratings	Three 10s trials of the individually calibrated heat stimulus rated 70/100 will be rated using using a "Pain Intensity" Visual Analog Scale rating scale with anchors "No pain" (coded -100) to "Most intense pain imaginable (coded 100)." Higher scores indicate more intense pain (worse outcome).	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)

Collaborators and Investigators

• Sponsor: University of California, San Diego

Study record dates

Study Major Dates

• Study Start (Actual): April 5, 2023
• Primary Completion (Actual): August 3, 2023
• Study Completion (Actual): August 3, 2023

Study Registration Dates

• First Submitted: April 4, 2022
• First Submitted That Met QC Criteria: April 11, 2022
• First Posted (Actual): April 14, 2022

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: December 10, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Reproductive Control Agents; Oxytocics; Oxytocin
• Other Study ID Numbers: 802467

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Deidentified data may be shared with other researchers per request.
• IPD Sharing Time Frame: Upon study completion for as long as possible.
• IPD Sharing Access Criteria: For academic researchers conducting reviews, meta-analyses, or secondary analyses.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No