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330 SEcTion iii EndocrinE ` endocrine—Physiology EndocrinE ` endocrine—Physiology

Prolactin
soUrce Secreted mainly by anterior pituitary. Structurally homologous to growth hormone.
FUnction Stimulates milk production in breast; inhibits Excessive amounts of prolactin associated with
ovulation in females and spermatogenesis  libido.
in males by inhibiting GnRH synthesis and
release.
regUlAtion Prolactin secretion from anterior pituitary Dopamine agonists (eg, bromocriptine) inhibit
is tonically inhibited by dopamine from prolactin secretion and can be used in
tuberoinfundibular pathway of hypothalamus. treatment of prolactinoma.
Prolactin in turn inhibits its own secretion Dopamine antagonists (eg, most antipsychotics,
by  dopamine synthesis and secretion from metoclopramide) and estrogens (eg, OCPs,
hypothalamus. TRH  prolactin secretion (eg, pregnancy) stimulate prolactin secretion.
in 1° or 2° hypothyroidism).

Sight/cry of baby Higher cortical centers

Hypothalamus

Medications
Chest wall injury (via ANS) Dopamine TRH 1° hypothyroidism
Nipple stimulation

Posterior
Anterior pituitary
pituitary

Estrogen Pregnancy
Reduced prolactin
elimination FSH
Prolactin GnRH Ovulation
Renal failure Spermatogenesis
LH

Milk production

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