Sex Steroids and the Serotonin Transporter

Study Overview
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Brief Summary
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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.

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

Conditions
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Transsexualism

Intervention / Treatment
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* Drug: Testolactone undecanoate
* Drug: Lynestrenol
* Drug: Cyproterone Acetate
* Drug: Estradiol
* Drug: 5-alpha reductase inhibitor


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: hormone treatment for MtF<br>cyproterone acetate estradiol alpha-5-reductase-inhibitor | Drug: Cyproterone Acetate<br>* 50mg per day<br>* Other names: Androcur®;Drug: Estradiol<br>* 100 microgram TTS twice a week<br>* Other names: Estradot®;Drug: 5-alpha reductase inhibitor<br>* 1mg daily<br>* Other names: Finasterid®;|
| Experimental: hormone treatment for FtM<br>testosterone undecanoate lynestrenol | Drug: Testolactone undecanoate<br>* 4ml i.m.<br>* Other names: Nebido®;Drug: Lynestrenol<br>* 2/day<br>* Other names: Orgametril®;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change in serotonin-transporter binding potential (BP) in predefined brain regions, measured by Positron Emission Tomography | 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 | 5 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Serotonin Transporter, Hormone therapy, Gender Dysphoria, Transsexualism