Description

Testosterone is a synthetic form of the endogenous androgenic steroid testosterone. In vivo, testosterone in target tissues is irreversibly converted to dihydrotestosterone (DHT) by the enzyme 5-alpha-reductase.

Androgen receptor and testosterone ligand or DHT complexes act as transcription factor complexes, stimulating the expression of several sensitive genes.

DHT binds with greater affinity to androgen receptors than testosterone, thus activating gene expression more efficiently. In addition, testosterone is irreversibly converted to estradiol by a complex of aromatase enzymes, particularly in the liver and adipose tissue.

Testosterone and DHT support the development and maintenance of male sex characteristics related to internal and external genitalia, skeletal muscles and hair follicles; estradiol promotes pineal maturation and bone mineralization. Due to the rapid metabolism in the liver, testosterone is usually administered for therapeutic purposes as an ester derivative.