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

Mechanisms of Testosterone-Driven Growth-Hormone (GH) Secretion in Aging Men: Modulation of GHRH, GHRP and Somatostatin Action by Estrogenic Versus Androgenic Steroids

Status

Completed

Phases

Phase 1

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT00309855

Enrollment

Registered

2006-04-03

Start date

2005-12-31

Completion date

2008-08-31

Last updated

2012-07-31

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

Conditions

Aging

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

Interventions

DRUGPlacebo

im and orally

DRUGTestosterone

injections

DRUGAnastrazole

orally x 21 days

DRUGDutasteride

orally x 21 days

Study design

Allocation

RANDOMIZED

Intervention model

CROSSOVER

Primary purpose

BASIC_SCIENCE

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

MALE

Age

50 Years to 80 Years

Healthy volunteers

Yes

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.

Design outcomes

Primary

Measure	Time frame	Description
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).

Countries

United States

Outcome results

None listed

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