27.02.5 Prolactin Excess

Prolactin is a peptide hormone secreted by lactotrophic cells in the anterior pituitary. Increases in prolactin secretion, during pregnancy, results in maturation of milk secreting duct in the mammary gland. Although not restricted to pregnant women, excess production of prolactin (hyperprolactinaemia) will result in overactive, secreting mammary tissue. Prolactin secretion is under the control of D2 dopamine receptors in the lactotrophic cells.

Dopamine, secreted from the hypothalamus, acts on these receptors to inhibit the prolactin production. Hyperprolactinaemia results when circulating levels of dopamine drop and the inhibitory processes compromised resulting in large levels of circulating prolactin in the blood. Treatment is with bromocriptine, a dopamine receptor agonist, which decreases excessive prolactin secretion. Adverse effects include nausea and vomiting, dizziness and constipation.