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 - growth hormone (somatropin) - 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 gynecomastia.
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
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...