Synthetic HGH is comprised mainly of the 22Kda (kilodalton) isoform. Natural HGH the body produces is comprised of a multitude of different HGH isoforms with different binding affinities. The 22Kda isoform makes up the majority of monomeric HGH the body produces, yet is still a very small total percentage compared to the ratios the pituitary releases.
22Kda GH has an extremely high binding affinity to the extracellular prolactin receptor domain (PRL-R). To a greater extent than 20Kda HGH or other HGH dimers, tetramers, etc.
This means that synthetic 22Kda HGH WILL activate the PRL-R just as prolactin would.
So, it is not an increase in prolactin, but rather the direct HGH affinity for the prolactin receptor that causes the sides attribited to prolactin induced gyno.
In this case Dostinex (Cabergoline) or Bromocriptine would not work. Those are dopamine agonists which have an effect on lowering actual prolactin levels. Since 22Kda HGH is responsible for agonizing the prolactin receptor, this will not remedy this scenario.
It could, however, help slightly at best, if and only if actual prolactin is also a significant contributing factor regardless of the HGH supplementation.
Example:
Both circulating 22Kda HGH and Prolactin are binding to the PRL-R in the breast tissue. Using Cabergoline could decrease prolactin to a degree, thus lowering the combined total of both...