Once we have added in the necessary testosterone, the next step is controlling the impending estrogen and progesterone activity that will result from the use of the Nandrolone hormone. This makes the use of anti- estrogens highly recommended; most will need an Aromatase Inhibitor (AI). However, if we suppress estrogenic activity too much, this can lead to complications; it can lead to sexually related side effects as well as damage cholesterol. Conversely, if we do not control estrogen and let the hormone run wild, high levels of estrogen can lead to gynecomastia , water retention and also negatively affect sexual function. Find the right balance of testosterone to estrogen and you will not have a problem when stacking Deca Durabolin.
As demonstrated in progesterone receptor-deficient mice, the physiological effects of progesterone depend completely on the presence of the human progesterone receptor (hPR), a member of the steroid-receptor superfamily of nuclear receptors. The single-copy human (hPR) gene uses separate promoters and translational start sites to produce two isoforms, hPR-A and -B, which are identical except for an additional 165 amino acids present only in the N terminus of hPR-B.  Although hPR-B shares many important structural domains with hPR-A, they are in fact two functionally distinct transcription factors, mediating their own response genes and physiological effects with little overlap. Selective ablation of PR-A in a mouse model, resulting in exclusive production of PR-B, unexpectedly revealed that PR-B contributes to, rather than inhibits, epithelial cell proliferation both in response to estrogen alone and in the presence of progesterone and estrogen. These results suggest that in the uterus, the PR-A isoform is necessary to oppose estrogen-induced proliferation as well as PR-B-dependent proliferation.
Sex hormone-binding globulin (SHBG) is thought to mainly function as a transporter and reservoir for the estradiol and testosterone sex hormones. However it has also been demonstrated that SHBG can bind to a cell surface receptor (SHBG-R). The SHBG-R has not been completely characterized. A subset of steroids are able to bind to the SHBG/SHBG-R complex resulting in an activation of adenylyl cyclase and synthesis of the cAMP second messenger. [ 19 ] Hence the SHBG/SHBG-R complex appears to act as a transmembrane steroid receptor that is capable of transmitting signals to the interior of cells.