Prolactin is a hormone synthesized in the adenohypohyseal lactotrophs
, has no known target organ or defined role in male reproduction.
Dopamine attaches to D2 receptors, thereby causing arrest of PRL release by lactotrophs.
During pregnancy, estrogen-stimulated lactotroph hyperplasia leads to a progressive increase in serum PRL and a 10-fold increase at term.
Dopamine is known to be the primary regulator of prolactin release from lactotrophs
in the anterior pituitary.
Possibility of spared lactotrophs getting disinhibited from hypothalamic inhibition or a small prolactinoma located in the pituitary remnant cannot be ruled out with the present day imaging techniques.
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).
Bromocriptine is a semisynthetic ergot alkaloid that binds to receptors on normal and tumor lactotrophs
and inhibits the synthesis and secretion of prolactin.
The search for the prolactin-suppressive principle(s) yielded a number of compounds with dopaminergic properties: they bound to recombinant DA2-receptor protein and suppressed prolactin release from cultivated lactotrophs as well as in animal experiments.
When dopamine or dopaminergic compounds were added, prolactin secretion b y the lactotrophs was dose-dependently inhibited.
The release of prolactin by the lactotrophs was stimulated by high intracellular cAMP levels.
The low prolactin level suggested that there may have been destruction of the lactotrophs
Prolactin (PRL) is a 23-kDa protein hormone secreted mainly by the lactotrophs
in the anterior pituitary gland and also at low concentrations by several other tissues (1).