Human Growth hormone (HGH), also known as somatotropin or somatropin, is a peptide hormone that stimulates growth, cell reproduction and regeneration in humans and other animals. It is a type of mitogen which is specific only to certain kinds of cells. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland. Many factors influence the release of Human Growth Hormone, however, including nutrition and exercise.
Due to its chemical structure nandrolone is weakly exposed to aromatase (only 20% of the aromatizing activity of testosterone). However, not estrogenic effects are its main concern: nandrolone has a potent progestogenic activity (20% of progesterone). While binding to progestogenic pituitary receptors nandrolone causes increased production of prolactin, which in effect is very similar to estrogen: its effect presents in reducing testosterone production, increasing fat mass and in gynecomastia. To prevent these side effects prolactin inhibitors (cabergoline) shall always be at hand when on nandrolones cycle.