Sex Steroids and the Serotonin Transporter

The Influence of Sex Steroid Hormones on Serotonin Transporter Binding in the Human Brain Investigated by Positron Emission Tomography

Status

Completed

Phases

Phase 4

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT01065220

Enrollment

Registered

2010-02-09

Start date

2010-02-28

Completion date

2014-01-31

Last updated

2014-01-03

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

Conditions

Transsexualism

Keywords

Serotonin Transporter, Hormone therapy, Gender Dysphoria, Transsexualism

Brief summary

The aim of this study is to prove the influence of the sex steroid hormones estrogen, progesterone and testosterone on the serotonin transporter (5-HTT) binding using positron emission tomography (PET) and the selective radioligand \[11C\]DASB. Specifically, the 5-HTT binding will be quantified before and after hormone therapy underwent by 10 male-to-female (MtF) and 10 female-to-male (FtM) transsexuals urging for hormone treatment. The high-level, long-term administration of opsite sex steroid hormones in transsexuals provide the unique opportunity to investigate the influence of sex steroid hormones on the serotonergic system. Since the serotonin transporter serves as a primary target molecule for antidepressant treatment, the results of the study will be of benefit for the assessment of the clinical relevance of estrogen and testosterone as modulatory and neuroactive agents.

Interventions

DRUGTestolactone undecanoate

4ml i.m.

DRUGLynestrenol

2/day

DRUGCyproterone Acetate

50mg per day

DRUGEstradiol

100 microgram TTS twice a week

DRUG5-alpha reductase inhibitor

1mg daily

Study design

Allocation

NON_RANDOMIZED

Intervention model

SINGLE_GROUP

Primary purpose

BASIC_SCIENCE

Masking

NONE

Eligibility

Sex/Gender

ALL

Age

18 Years to 55 Years

Healthy volunteers

Inclusion criteria

* somatic health * no previous sex hormone medication * willingness to sign the written informed consent

Exclusion criteria

* severe diseases * steroid hormone treatment within 6 months prior inclusion * treatment with psychotropic agents such as selective serotonin reuptake inhibitors (SSRIs) * any implant or stainless steel graft * positive urine pregnancy test in women at the screening visit at each PET day

Design outcomes

Primary

Measure	Time frame	Description
change in serotonin-transporter binding potential (BP) in predefined brain regions, measured by Positron Emission Tomography	5 months	The serotonin-transporter BP will be assessed in a 90 min. dynamic PET measurement session at three timepoints: before start of hormonal therapy, after four weeks of hormonal therapy, and after 4 months of hormonal therapy

Countries

Austria

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026