the myth of nolvadex increasing PGR activation

[Matsuo Munefusa.]

There is a myth within the bodybuilding community that nolvadex, what could be termed a synthetic estrogen or an estrogen blocker (selective estrogen receptor modulator, ie SERM) depending on the perspective, can increase PGR activation when used in conjunction with progesterone AAS (ie trenbolone, nandrolone). The myth holds that using tamoxifen with nandrolone or trenbolone will worsen gyno symptoms.

I'd like in this post to point out why this myth was started and why this myth is false. I'd also like to add anecdotal information of my own at the end.

There were a few studies of tamoxifen noting how this drug increased PGR activation. [somebody have time to find these studies search pubmed: tamoxifen estrogen agonist endometrium].

The flaw is that tamoxifen is a mixed agonist/antagonist. In endometrial tissue (ie the cells of the uterus) the drug is an agonist, meaning it activates the estrogen receptor in similar way that estrogen itself does. Big surprise, there are estrogen receptors in the lining of the uterus! Also PGR receptors. Activating estrogen receptors is important cascade step in activating PGR receptors. Remember, no activation of estrogen receptors means no activation of PGR.

In breast tissue however, the drug is an antagonist, meaning it 'blocks' the receptor from being activated (by estrogen or an analogue). This is why the drug is primarily used to treat breast cancer in women (as well as for our purposes). If the estrogen receptor is blocked in breast tissue then the PGR receptor will not be activated despite the presence of progesterone AAS such as nandrolone (deca, NPP).


treatment for any type of gyno symptoms should include nolvadex therapy. Estrogen levels should be controlled by an aromatase inhibitor as a first line defense.

 

[Matsuo Munefusa.]

nobody wants to comment? I was hoping this would at least receive a pat on the back (haha) since it is such a common thing you hear on bodybuilding boards to NEVER take nolvadex with deca (or tren, etc).

 

[maakshif]

Deca's effects have shown to increase progesterone more so than prolactin, while nolvas ability to up-regulate the PgR could or could not have a true effect on us, it also does not actually handle the issue of both progesterone AND estrogen. Since higher estrogen is going to further any negative reactions in the body with progest, then an AI would be better suited for this purpose vs a SERM.

So basically, to handle estrogen and progesterone problems, start with an AI. If you are lactating, throw in some Nolva to stop it as quickly as possible to allow caber/prami to do its job.