T Nation

Letrozole As PgR Antagonist


#1

Ok, can anyone give me some info on whether letrozole is a PgR antagonist as well as an AI?
This is what I have read from another site:"the anti-estrogens letrozole or fulvestrant can lower progesterone levels, and combat any progestenic sides."

Now I know that fulvestrant is an ER and PgR antagonist. Well, I have read that it down regulates the ER and PgR proteins ... so effectively downregulates the activity of the receptor ... blah, blah, blah. So the use of fulvestrant seems justified. But I don't understand why letrozole would be recommended. I have found no information that suggests it is anything other than a highly effective AI. Anyone know otherwise?


#2

Google my name in quotations marks, and letrozole, and you'll find out that it does in fact lower Progesterone.


#3

Thank you Tony- for pointing me in the right direction and for the quick response.


#4

However it is limited in what it can do. If you plan on doing a gram of durabolin a week, you'll need to use somthing a little stronger, like bromocriptine.


#5

Why do you want to lower progesterone, specifically?


#6

sorry it took me so long to get back to you guys when you answered my questions so quickly. I tried my best to do some research so I don't look like a fool in this response.

Anyway. Tony- I am not worried about progesterone levels just yet. I wanted to know about letrozole for two reasons: 1) being purely academic- I read about letrozole and wanted to know more about it 2) I am planning a tren/winny/test cycle in the near future (and with tren being a progestin) might be using letrozole; although it may not be neccessary, but it is the easiest for me to get from my research chemical site.

As far as the bromocriptine goes, I thought it was anti-prolactin. But let me tell you what I know about it (or what i don't know): "Bromocryptine is a dopamine agonist; it decreases pituitary secretion of prolactin; clinically it can be used to treat hyperprolactinemia associated with parturition, abortion and prolactinomas.

Bromocryptine also decreases growth hormone secretion from the pituitary and it is used to treat acromegaly. Haloperidol is a drug that blocks dopamine receptors; it also blocks the effects of bromocryptine on prolactin release." But I have also read that bromocriptine may help in erectile funtion and may assist in PCT with testicular activation? So, P22 why did you suggest bromo?

I know that progesterone elevation from something like deca or tren along with prolactin elevation = a bad situation. But does bromo help with PgR antagonism as well?
I guess I have another dilemma with understanding how somethting like tren can increase prolactin levels.

I read that tren decreases T3 levels, and that patients with high prolactin levels also have compromised thyroid function. So does a decrease in T3 then decrease dopamine which in turn increases prolactin? If so, how does tren decrease T3 levels? Appreciate the help.