If you look closely at the steroid backbone of trenbolone, you will see that it resembles progesterone. Progesterone is a known killer of male libido in the doses we are talking about with regard to a "progestagenic" effect from the trenbolone. Some are more sensitive to this affect than others. As a side note: Male sex offenders are often giving long acting progesterone derivatives such as DepoProvera in order to kill libido. So, you don't need much of an affect to DECREASE libido.
This being said, the male breast tissue has both estrogen and progesterone receptors, just like females do. The catch is we don't have enough estrogen or progesterone in our systems under healthy normal conditions to stimulate breast growth (GYNO) in the male.
Now for the interesting stuff...where does male sex drive come from? It comes from...estrogen. Specifically and chemically, estradiol in the brain. Take a good amount of anti-aromatases with a long half-life and see what happens to your sex drive. Aromatase first drops systemically, and then when there is no longer enough conversion to estrogen anywhere in the body due to lack of aromatase, testosterone in the brain is unable to make the conversion to estradiol. Estradiol in the brain then falls, and so does old WILLY.
Trenbolone has a known ability to "cross react" with progesterone receptors. This is where the "progestagenic affect" comes from. Trenbolone resembles progesterone enough that it can stimulate its receptors. It seems to be an individualized type of affect. Some get it easily, some will never experience it, even at higher doses.
But the majority of humans have enough response to this "cross reactivity" that sex drive is affected and or gyno is possible from a drug that has this property. The same is true of anadrol. Anadrol is a DHT derivative which means it cannot aromatize. However, it has portions of its structure that can weakly stimulate progesterone receptors. This is how you can get gyno from anadarol.
On the surface, Cabaser or Cabergoline as a progesterone antagonist makes lots of sense if you are prone to loss of sex drive or progestagenic side effects from trenbolone. But if you really examine these drugs you will find that they are labeled primarily as "dopamine agonists". Dopamine is a "progesterone antagonist". But we are not needing to antagonize progesterone, we are trying to stop the progesterone-like affect of trenbolone. For this specific purpose, Cabaser or Cabergoline do not have much if any affect.
How is it that Cabaser or Cabergoline increase libido? Dopamine on its own, is a known stimulus to the sexual centers in the brain. So you have elevated dopamine but trenbolone is still free to "cross react" with the progesterone receptor. Which means, even if the Cabaser or Cabergoline bring sex drive up, you are still vulnerable to GYNO.
So what to do? I don't know. If this type of sensitivity exists to trenbolone, I would stay away from anabolics which are known to have a progestagenic affect. And definitely, do not take anti-estrogens with long half-lives that build up in your plasma while on a progestagenic drug. You will stimulate the shut off of libido in the brain by way of this affect and you will deplete estradiol systemically and in the brain, which will leave you on a Mountain in Tibet wearing a robe and shaving your head.
There is one caveat: many say winstrol has an anti-progestagenic affect. Because we do not have clinical literature on the proof of this, it is up to us in the underground. Personally, I have not noticed winstrol to do this among me or my friends. Plus, if it does, we do not know the mechanism, which means if it simply antagonizes progesterone and doesn't interfere with the receptor in some way, it will be as useless as Cabaser or Cabergoline. The trenbolone will still be free to mess with the progesterone receptors influencing gyno and Monk sexuality.
Any one out there confess to having libido issues on tren...then combining with winstrol and having the libido return? Interesting question that could help a lot of people if someone out there has this personal experience.