Testosterone-Driven Growth-Hormone (GH) Secretion in Aging Men

Phase 1

Completed

• Conditions: Aging
• Interventions: Drug: Placebo; Drug: Testosterone; Drug: Anastrazole; Drug: Dutasteride

• Registration Number: NCT00309855
• Lead Sponsor: Mayo Clinic

Brief Summary

This study is being done to understand how testosterone, the major male sex hormone, controls the pituitary gland's secretion of growth hormone (GH). GH is an important metabolic hormone, which controls sugar; fat and protein use in the body and maintains muscle strength and bone calcium content. Both testosterone and GH decline in older men. The age-related fall in these hormones probably contributes to relative frailty, reduced quality of life, bone loss, muscle wasting and impaired sexual function.

Detailed Description

Repletion of testosterone in older men drives pulsatile GH secretion via conjoint facilitation of feedforward by the primary secretagogues GHRH and GHRP and repression of feedback by the dominant inhibitor, somatostatin; and, in corollary, testosterone acts via aromatization to estradiol and/or reduction to 5 alpha-dihydrotestosterone

Study Timeline

• Study Start: 2005-12
• Study First Submitted: 2006-03-31
• Study First Submitted QC: 2006-03-31
• Study First Posted: 2006-04-03
• Primary Completion: 2008-08
• Study Completion: 2008-08
• Status Verified: 2012-07
• Last Update Submitted: 2012-07-27
• Last Update Posted: 2012-07-31

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Male
• Target Recruitment: 80

Inclusion Criteria

• healthy men between the ages of 50 and 80;
• normal weight (within 30% of ideal body weight defined by New York Metropolitan Life tables); and
• normal hematocrit (greater than 38%);
• community dwelling; and
• voluntarily consenting

Exclusion Criteria

• recent use of psychotropic or neuroactive drugs (within five biological half-live);
• obesity (outside weight range above);
• anemia (hematocrit < 38%);
• drug or alcohol abuse, psychosis, depression, mania or severe anxiety;
• acute or chronic organ-system disease;
• endocrinopathy, other than primary thyroidal failure receiving replacement;
• nightshift work or recent transmeridian travel (exceeding 3 time zones within 7 days of admission);
• acute weight change (loss or gain of > 2 kg in 6 weeks);
• allergy to administered compounds; and
• unwillingness to provide written informed consent.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Double Placebo	Placebo	(i.m. vehicle 0.5 mL weekly x three injections and oral placebo once daily x 21 days)
Testosterone IM and oral placebo	Testosterone	IM injections weekly x three injections and oral placebo once daily x 21 days
Testosterone and Oral Anastrozole	Testosterone	IM injections weekly x 3 injections and oral daily x 21 days
Testosterone and Oral Anastrozole	Anastrazole	IM injections weekly x 3 injections and oral daily x 21 days
Testosterone and Dutasteride	Testosterone	IM injections weekly x 3 injections and oral once daily x 21 days
Testosterone and Dutasteride	Dutasteride	IM injections weekly x 3 injections and oral once daily x 21 days

Primary Outcome Measures

Name	Time	Method
Growth Hormone concentration after injections	24 days	GH will be measured 4 different times mornings within 16-21 days following the first testosterone injection (day 1).

Trial Locations

Locations (1)

Mayo Clinic; 🇺🇸 Rochester, Minnesota, United States