4-androstenedione

4-Androstenedione (also known as androstenedione) is a steroid hormone that serves as a precursor in the biosynthesis of both testosterone and estrogens such as estrone and estradiol. It is an endogenous weak androgen and estrogen and is produced in the adrenal glands and gonads.

Biochemistry

4-Androstenedione is synthesized from dehydroepiandrosterone (DHEA) or from 17α-hydroxyprogesterone in the adrenal cortex and gonads. It is a key intermediate in the steroidogenesis pathway, which is the process by which steroids are generated from cholesterol and transformed into other steroids.

In the body, 4-androstenedione can be converted into testosterone by the enzyme 17β-hydroxysteroid dehydrogenase or into estrone by the enzyme aromatase. This conversion is crucial for maintaining the balance of androgens and estrogens in both males and females.

Physiological Role

4-Androstenedione plays a significant role in the development of secondary sexual characteristics and the regulation of reproductive functions. In males, it is a precursor to testosterone, which is essential for the development of male characteristics and reproductive tissues. In females, it serves as a precursor to estrogens, which are vital for the regulation of the menstrual cycle and reproductive system.

Clinical Significance

4-Androstenedione levels can be measured in the blood to assess adrenal and gonadal function. Abnormal levels may indicate disorders such as polycystic ovary syndrome (PCOS), adrenal hyperplasia, or androgen-secreting tumors.

Use in Sports and Supplements

4-Androstenedione gained popularity as a dietary supplement in the 1990s, marketed for its potential to increase muscle mass and strength by boosting testosterone levels. However, its use as a supplement has been controversial due to potential health risks and its classification as a prohormone. In 2004, the United States banned the sale of androstenedione as a dietary supplement due to concerns about its safety and potential for abuse in sports.

Also see

• Testosterone
• Estrone
• Estradiol
• Steroidogenesis
• Dehydroepiandrosterone
• 17β-Hydroxysteroid dehydrogenase
• Aromatase