Dissecting the Role of Estradiol in Mediating Gender-specific Anxiolytic and Prosocial Effects of Oxytocin

What Was Tested

In this phase 1 trial, researchers set out to test Oxytocin.

The study aims to examine a behavioral and neural framework for understanding the sex-specific effects of the neuropeptide oxytocin (OXT).

Using hormonal, behavioral and neuroimaging readouts, it is planned to explore the interplay of OXT and estradiol as a potential mechanism mediating sexual dimorphic effects.

It had four arms (groups): 1. Oxytocin spray, 2. Estrogen gel (experimental), 1. Oxytocin spray, 2. Placebo gel (experimental), 1. Placebo spray, 2. Estrogen gel (experimental) and 1. Placebo spray, 2. Placebo gel (placebo comparator).

The registry classes the interventions as drug.

More on the Plan

The study comprises two subprojects (Study 1 and Study 2).

In Study 1, the investigators will compare the effects of OXT on fear extinction and fear recall as well as on emotion recognition between women and men.

Additionally, the investigators plan to test whether a pretreatment with exogenous estradiol can be used to augment these OXT effects.

In Study 2, the investigators will use functional magnetic resonance imaging (fMRI) to elucidate the effects of OXT-estradiol interactions on neural responses in an emotional face matching task and an emotional memory task.

Who Took Part

Enrollment: 487 actual participants took part.

It was open to people of any sex aged from 18 years up to 40 years.

Healthy volunteers could join, not only people with the condition.

Examples of who could join: Healthy male \& female volunteers. Women will be tested in their follicular phase (Day 0-5).

The full record lists 3 inclusion and 6 exclusion criteria; among the exclusions: hormonal contraception; current psychiatric illness; current psychiatric medication or psychotherapy.

How the Study Was Run

Design: randomized, factorial and double-blind.

Random assignment meant chance, not the researchers, decided who got Oxytocin and who got the comparison, which limits bias.

Neither the participants nor the staff measuring them knew who was on Oxytocin, so expectations could not easily colour the readings.

Those kept unaware of assignments: participant and investigator.

It started in 2016-09-18 with completion listed for 2020-01-25.

It ran at 1 site in Germany.

Its stated primary purpose is basic science.

What Was Measured

Primary outcome: Electrodermal responses to fear-conditioned stimuli (time frame: 3 hours after gel administration and 30 minutes after nasal spray administration). Emotion recognition thresholds (time frame: 200 minutes after gel administration and 50 minutes after nasal spray administration). Resting state functional connectivity (time frame: 3 hours after gel administration and 30 minutes after nasal spray administration).

It also tracked 7 secondary outcomes, for example Changes in oxytocin plasma concentration, Changes in estrogen plasma concentration, Contingency ratings of fear-conditioned stimuli, Ultimatum game tasks, Delayed discounting task and Changes in the Multifaceted Empathy Test (MET).

What This Means in Plain Language

Put simply, this is a phase 1, randomized trial of Oxytocin in 487 people.

The trial is marked completed; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Oxytocin compound page, all human trials.