As the gland expands, there is a simultaneous increase in the size and population of lactotroph
cells and a progressive increase in serum prolactin (Imran, Ur, & Clarke, 2007).
Prolactin (PRL) is a polypeptide hormone, secreted by lactotroph
cells of anterior pituitary.
During pregnancy, estrogen-stimulated lactotroph
hyperplasia leads to a progressive increase in serum PRL and a 10-fold increase at term.
5,9) GHRH induced acromegaly exhibits mild hyperprolactinemia due to hyperstimulation of pituitary lactotroph
cells by GHRH, as seen in human GHRH transgenic mice.
PRL is produced primarily by lactotroph
cells in the anterior pituitary gland, but also is produced and is active in breast tissue and mammary glands, placenta and decidua, bone marrow cells, lymphocytes (T cells and B cells), and other tissues.
32 Generally, aggressive behavior is a phenomenon of clinically silent hormone-containing adenomas and unusual plurihormonal adenomas as well as the rare lactotroph
adenoma with GH immunoreactivity, known as the "acidophil stem cell adenoma.
Regulation of prolactin secretion at the level of the lactotroph
Preservation of lactotroph
function or presence of hyperprolactinemia is exceedingly rare and have been reported before the availability of modern imaging tools as magnetic resonance imaging (MRI) (6).
However, regarding the mechanisms of their effects, inhibitors of prolactin secretion by the prolactin-producing cells of the anterior pituitary are thought to produce their effects by a direct agonistic action on dopamine D2 receptors on lactotroph
and thyrotroph function in three-week-old gilts reared in a hot or cool environment.
Leukemia inhibitory factor regulates prolactin secretion in prolactinoma and lactotroph
The most likely explanation is the rapid change in hormonal milieu that occurs within 24 hours of delivery, when concentrations of both oestrogen and progesterone decrease, which decreases the stimulation of prolactin-producing lactotroph
cells and oestrogen receptors on some prolactinomas (9).