The Effect of 5-Alpha Reductase on Testosterone in Men
The enzyme 5-alpha reductase is present in small amounts in muscle and converts testosterone to dihydrotestosterone (DHT). Testosterone affects lean body tissue, muscle size, muscle strength, and sexual function in men. This study will evaluate how 5-alpha reductase influences the effects of testosterone in young healthy men.
Testosterone, the predominant circulating androgen in men, serves as the active hormone in some target tissues; however, testosterone effects in other target organs require its conversion to two active metabolites, estradiol 17-beta and DHT. The role of 5-alpha reductase in mediating testosterone's effects on muscle and sexual function remains unclear. This study will determine whether 5-alpha reduction of testosterone to DHT is necessary for mediating effects on fat-free mass, muscle size, muscle strength, and leg power in men. The study will also evaluate the necessity of 5-alpha reductase for maintenance of androgen effects on sexual function (sexual desire, overall sexual activity, nocturnal penile tumescence [NPT], response to visual erotic stimulus, and penile rigidity) in men.
Participants in this study will be treated with a drug to suppress endogenous testosterone production. Participants will then be randomly assigned to receive either testosterone and placebo or testosterone and the 5-alpha reductase inhibitor dutasteride. Testosterone will be administered weekly; dutasteride and placebo will both be administered daily. Diet and exercise will be standardized across both groups. Participants will be assessed at study entry and Week 20. Assessments will include measurements such as a DEXA scan, MRI scan, and muscle performance and sexual function tests. Participants will also have blood tests for safety monitoring; blood tests will include measures of hematocrit, liver enzymes (AST and ALT), prostate specific antigen (PSA), and cholesterol.
Allocation: Randomized, Control: Placebo Control, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double-Blind, Primary Purpose: Treatment
testosterone enanthate, duastride
Charles R. Drew University
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
Results (where available)
- Source: http://clinicaltrials.gov/show/NCT00070733
- Information obtained from ClinicalTrials.gov on July 15, 2010
Medical and Biotech [MESH] Definitions
Steroidal compounds related to TESTOSTERONE, the major mammalian male sex hormone. Testosterone congeners include important testosterone precursors in the biosynthetic pathways, metabolites, derivatives, and synthetic steroids with androgenic activities.
A potent androgenic metabolite of TESTOSTERONE. Dihydrotestosterone (DHT) is generated by a 5-alpha reduction of testosterone. Unlike testosterone, DHT cannot be aromatized to ESTRADIOL therefore DHT is considered a pure androgenic steroid.
A potent androgenic steroid and major product secreted by the LEYDIG CELLS of the TESTIS. Its production is stimulated by LUTEINIZING HORMONE from the PITUITARY GLAND. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to DIHYDROTESTOSTERONE or ESTRADIOL.
An ester of TESTOSTERONE with a propionate substitution at the 17-beta position.
A progesterone that has been used in ESTRUS SYNCHRONIZATION and has been evaluated as an injectable contraceptive in combination with estradiol enanthate. It is also used therapeutically as a topical anti-inflammatory and is applied topically in the treatment of ACNE.
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