Peripheral Oxytocin and Touch

Effect of Peripheral Oxytocin on Touch Pleasantness and Pain

Status

Completed

Phases

Phase 2

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT05326776

Acronym

POPP

Enrollment

Registered

2022-04-14

Start date

2023-04-05

Completion date

2023-08-03

Last updated

2024-12-31

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Healthy Adults

Brief summary

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.

Interventions

DRUGPitocin

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.

Study design

Allocation

RANDOMIZED

Intervention model

CROSSOVER

Primary purpose

BASIC_SCIENCE

Masking

QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender

ALL

Age

18 Years to 65 Years

Healthy volunteers

Yes

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

Design outcomes

Primary

Measure	Time frame	Description
Change in Mean Pleasantness Rating of Gentle Brushing	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)	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).
Change in Mechanical Threshold	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)	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.
Change in Temporal Summation of Pinprick Stimuli	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)	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.

Secondary

Measure	Time frame	Description
Pressure Pain Threshold	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)	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.
Heat Pain Threshold	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)	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.
Heat Pain Ratings	Baseline and time of intervention at both the Oxytocin Session and Placebo Session (Sessions spaced a minimum of 3 days apart)	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).

Countries

United States

Participant flow

Recruitment details

Healthy adults were recruited from the local community as well as from our previous studies. Potential participants completed a telephone screening during which the study procedures were described, and eligibility criteria were reviewed.

Pre-assignment details

Screening was conducted prior to enrollment. No participants were excluded after enrollment.

Participants by arm

Arm	Count
Order 1 Participants will receive 4mcg/2ml oxytocin during Session 1 and 2ml isotonic saline during Session 2, injected into the forearm. 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.	10
Order 2 Participants will receive 2ml isotonic saline during Session 1 and 4mcg/2ml oxytocin during Session 2, injected into the forearm. 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.	10
Total	20

Baseline characteristics

Characteristic	Total	Order 1	Order 2
Age, Continuous	27.4 years STANDARD_DEVIATION 9.8	28.6 years STANDARD_DEVIATION 12.5	26.2 years STANDARD_DEVIATION 6.5
Race and Ethnicity Not Collected	0 Participants	—	—
Region of Enrollment United States	20 participants	10 participants	10 participants
Sex/Gender, Customized gender female	12 Participants	5 Participants	7 Participants
Sex/Gender, Customized gender male	7 Participants	4 Participants	3 Participants
Sex/Gender, Customized gender non-binary	1 Participants	1 Participants	0 Participants

Adverse events

Event type	EG000 affected / at risk	EG001 affected / at risk
deaths Total, all-cause mortality	0 / 18	0 / 18
other Total, other adverse events	0 / 18	0 / 18
serious Total, serious adverse events	0 / 18	0 / 18

Outcome results

Primary

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).