Cardiovascular Effects of Androgens

Androgens are the male sex hormones responsible for development of the male reproductive system. Testosterone is the main androgen, however, other circulating androgens also exist; these are dehydroepiandrosterone, androstenedione and androstenediol. In some tissues, testosterone can be converted to dihydrotestosterone by action of 5┙-reductase. Testosterone is also found in females, but at much lower levels than males; it can be converted into estradiol by the enzyme aromatase. Testosterone has 19 carbon atoms, and is produced from cholesterol, mainly by Leydig cells in the testes. Androgens are responsible for primary and secondary sexual characters in men, and also for the development of skeletal muscle mass and strength, erythropoiesis and bone density, amongst other functions. The divergent effects that androgens have between sexes can be explained by differences in concentration, metabolism and receptor expressions. Male sex hormones are also known to fluctuate along the day and throughout life. Prior to puberty, testosterone level is usually low in males. However, after puberty, testosterone level increases and reaches its peak around the age of 20-25 in men. As aging occurs, testosterone levels decline. Testosterone and its derivatives are well known for their androgenic properties and anabolic effects. These hormones direct the differentiation of organs and tissues towards the adoption of male phenotypes. Thus far, the effects of androgens on the cardiovascular system remain incompletely understood. Some studies point to increased cardiovascular risk associated with a high circulating androgen level, related to responses that lead to changes in blood pressure, ion channel activity and cardiomyocyte hypertrophy. However, other studies support a long-term cardio-protective role for these steroid hormones. Despite these differences, increasing clinical evidence supports consideration for transient use of testosterone derivatives to improve cardiovascular function.