Anabolic-androgenic steroids are called male sex hormones. The most important one of these hormones is testosterone.

By men, testosterone is produced in testicles. It is synthetized from cholesterol. A simplified principle of regulation of its production is described in following part.

Production of testosteron in human body

When the level of testosterone sinks under a concrete level, which is different by every individual, the hypothalamus starts producing GnRH (gonadotropin-releasing hormone). By its action in the pituitary gland, it increases production of LH (luteinizing hormone) and FSH (follicle-stimulating hormone). By men, LH stimulates production of Leydig‘s cells in testicles and leads to production of androgen hormones – testosterone. Together with testosterone, FSH stimulates Sertolli‘s cells in testicles, which cause development of spermatozoon. To be developed in a right way, spermatozoon need to „swim“ in testosterone.

Probably, it is not necessary to discuss, where the majority of testosterone goes. The rest of testosterone goes to blood, where it is absorbed by liver from 97 – 99 %. The rest of it heads to sex organs and muscle cells, where they can sometimes contribute to growth of muscles.

In this moment, the level of testosterone is already high and the reverse process begins. Testosterone acts in hypothalamus and it suppresses the production of GnRH. Transformation of a part of testosterone in estrogens (female sex hormones) appears, as well. This process ensures the regulation of the level of testosterone in the body.

The mentioned mechanism of action is so called axis hypothalamus – pituitary gland – testicles. By men aged 20 – 50, around 7 mg of natural testosterone are produced every day. The production of LH and FSH is always the same, their levels correlate. Only a little part of the production of testosterone ensures the growth of muscles. For the organism, the production of spermatozoon is much more important than the growth of muscles, which means, that spermatogenesis is the priority. This process is repeated every 1-3 hours.

Influence of testosterone on the organism

  • -    It contributes to the metabolism of proteins and simultaneously it reduces their catabolism.
  • -    It stimulates the growth of organs.
  • -    It stimulates spermatogenesis.
  • -    It is closely connected to the mental state of sexual desire, libido and aggression.
  • -    It has anabolic influence on muscles, bones and skin.
  • -    It closes epiphysis of long bones.
  • -    It influences the size of ejaculatory ducts.
  • -    It influences the psychological perception of reality and perspectives, above all in connection to the vision of a body, identity and personality.
  • -    It contributes to the sexual characteristics of a man (in adolescence it contributes to the growth of larynx, it contributes to the development of body hair, it increases the secretion of fat glands, in contributes to the growth of muscle mass).


Testosterone in medicine

In medicine, testosterone is also applied in situations, when the production of the hormone by the patient is abnormally low. It is also prescribed for treating breast cancer by women. In high doses, it can have positive influence on some blood diseases, which could be fatal. During adolescence, it contributes to the growth of boys and simultaneously it ensures the development of male characteristics (body hair, voice, testicles, penis, and skeletal muscles).