Androgen refers to sexual hormones belong to male. For some instances, androgens include testosterone, dehydroepiandrosterone (DHEA), androstenedione, androsteron, dihydrotestosterone (DHT), and androstenediol. Derived from cholesterol that undergoes group modification, androgens have various effects towards physical and psychological aspects of male. The main function of androgens is related to the reproductive and sexual function of men. Testosterone is the male main androgen, which regulates the manhood and maleness.
Male reproductive system regulates male sexual structural changes, male masculinity, and the hormonal changes that undergo with the same pathway of male puberty is very important for the male fertility and spermatogenesis. Under Luitenizing Hormon (LH) and Interstitial Cells Stimulating Hormone (male FSH) from Hypophysis, the Leydig’s cells produce testosterone. While Sertoli cells actively foster the spermatogonia, and provide proteins and growth factor for them to go through spermatogenesis, and matured into spermatozoa. Testosterone is not only important for the spermatogenesis, but also sexual libido stimulation and manhood sexual functions.
Testosterone belongs to steroid hormones, and its receptors located both in the nucleus of cells, also cellular cytoplasm. In the blood circulation, testosterone binds to globulins, SHGB 30% and albumin 70%. Free testosterone in the blood circulation is around 0.5-3%.
Secretion mechanism is regulated by GnRH of hypothalamus, induces the releasing of LH and FSH from hypophysis, through blood circulation delivered to the Seminiferous tubules, activating Leydig cells to synthesize and secrete testosterone. 95% of circulated testosterone is secreted by testes, while 5% comes from Adrenal Gland Cortex, Reticularis Zone. Dihydrotestosterone (DHT) acts in the external genital organ development, prostate gland development, acnes, male hair (chest hair, armpit, pubic hair, hand and leg hair all body hair) also development of baldness. Testosterone is a body-building hormone, gives effects towards muscle mass, and bone growth. Spermatogenesis and Wolfii duct development also initiated by testosterone.
Androgen synthesis begins when LH binds to its seven transmembrane, G protein-coupled receptor that activate the cyclic AMP pathway. Stimulation of the LH receptor induces Steroid Acute Regulatory (StAR) protein that works along with several steroidogenic enzymes involved in androgen synthesis.
In the reticular zone of adrenal gland, and in the interstitial cells of Leydig, androgens biosynthesis generated. The process initiated by conversion of cholesterol into pregnenolone. Pregnenolone then converts into androstenedione and or dehydroepiandrosterone (DHEA converts into androstenedione). Androstenedione transforms into testosterone. Testosterone can transform into Dihydrotestosterone catalyzed by 5-alpha-reductase enzyme. Testosterone secretion rates is around 4-9 mg/day in normal adult male.
Androgen influenced men’s malehood and maleness. More muscle mass, less fat mass, supports men’s activities, that related to outdoor activities that need more musculoskeletal and physical acts. Male skin composition thicker and rich of sebaceous and sudoriferous glands, help them to adapt the sunrays and Ultraviolet rays. Oily skin helps to trap pathogens, and sweat includes in the physiological thermoregulatory mechanism. Reproductively, androgen causes masculine and virilize male, that attracts female. Women tend to attracted with muscular male, and looked much more masculine.
Prof, Jameson, J. Larry, MD, PhD. Harrison’s Endocrinology 2nd Edition. 2010. McGraw Hill Medicine. China
William F Ganong MD, .Review of Med. Physiol. 22nd Edition. 2008. EGC. Jakarta