Ok bouncer and Rado I found it.
The human body always prefers to remain in a very balanced hormonal state, a tendency known as homeostasis. When the administration of androgens from an outside source cause a surplus of hormone, it will cause the body to stop manufacturing its own testerone. Specifically, this happens via a feedback mechanishm where the hypothalamus detects a high level of sex steroids (including androgens, progestins, and estrogens) and shuts off the release of GnRH (Gonadotropin Releasing Hormore, formerly referred to as luteinizing hormone releasing hormone). This , in turn, causes the pituitary to stop releasing luteinizing hormone and FSH (follicle stimulating hormone), the two hormones (primarily LH) that stimulate the Leydig's cells in the testes to release testosterone (negative feedback inhibition has been demonstrated at the pituitary level as well). Without stimulation by LH and FSH, the testes will be in a state of production limbo, and may shrink from inactivity. In extreme cases the steroid user can notice testicles that are unusually and frightingly small. However, this effect is temporary, and once the drugs are removed (the hormone levels rebalanced) the testicles should return to their original size. Many regular steroid users find this side effect quite troubling, and use HCG during a steroid cycle in order to try to maintain testicular activity (and size) during treatment. The more estrogenic androgens (testosterone, Anadrol, and Dianobol) are most dramatic in this regard, and are not the best choices for individuals who seriously want to avoid testicle shrinkage. Non-aromatizing anabolics would be a better option, however, be warned that all steroids will suppress the production of testosterone if taken at an anabolicly effective dosage (yes, even Anavar and Primobolan)
The human body always prefers to remain in a very balanced hormonal state, a tendency known as homeostasis. When the administration of androgens from an outside source cause a surplus of hormone, it will cause the body to stop manufacturing its own testerone. Specifically, this happens via a feedback mechanishm where the hypothalamus detects a high level of sex steroids (including androgens, progestins, and estrogens) and shuts off the release of GnRH (Gonadotropin Releasing Hormore, formerly referred to as luteinizing hormone releasing hormone). This , in turn, causes the pituitary to stop releasing luteinizing hormone and FSH (follicle stimulating hormone), the two hormones (primarily LH) that stimulate the Leydig's cells in the testes to release testosterone (negative feedback inhibition has been demonstrated at the pituitary level as well). Without stimulation by LH and FSH, the testes will be in a state of production limbo, and may shrink from inactivity. In extreme cases the steroid user can notice testicles that are unusually and frightingly small. However, this effect is temporary, and once the drugs are removed (the hormone levels rebalanced) the testicles should return to their original size. Many regular steroid users find this side effect quite troubling, and use HCG during a steroid cycle in order to try to maintain testicular activity (and size) during treatment. The more estrogenic androgens (testosterone, Anadrol, and Dianobol) are most dramatic in this regard, and are not the best choices for individuals who seriously want to avoid testicle shrinkage. Non-aromatizing anabolics would be a better option, however, be warned that all steroids will suppress the production of testosterone if taken at an anabolicly effective dosage (yes, even Anavar and Primobolan)

Comment