PROLACTIN IN
MAMMALS
By: Megan the epic M, Erica the fried squid pickel, Abby,
Alyssa, Katie, Hiba
GLAND
• Prolactin is produced in the pituitary gland in response
to pregnancy and nursing.
BASE
• Peptide-based
• It is a pituitary polypeptide
• Alpha helix folded
PATHWAY/MECHANISM
• Peptide hormone binds to a receptor on the outside of
the cell membrane which activates the Jak2 kinase.
Stat5, a transcription factor, is activated by Jak2. Stat5
then goes into the nucleus and hooks onto the DNA
triggering a cellular response.
PROLACTIN’S CELLULAR
RESPONSE
• Differentiation of the mammary gland which causes
the production of the milk proteins.
• WAP- encodes for milk proteins
• BLG- encodes for milk proteins
• Casein- encodes for milk proteins
NEGATIVE FEEDBACK
LOOP
• Suckling is the major stimulus of
prolactin production
• Thyrotropin-releasing factor
stimulated by hypothalamus.
• TRH is sent to pituitary gland
• Pituitary gland releases prolactin
• Prolactin stimulates milk
production in breasts beginning in
late pregnancy and sustained after
birth.
• When the mother no longer needs
to produce milk, dopamine inhibits
prolactin by signaling the
hypothalamus to stop.
ALTERING PATHWAY
• In malignant tissues prolactin fails to trigger,
differentiation, and instead enhances breast epithelial
survival and motility.
• Prolactin, when over-expressed, inhibits apoptosis in
cervical cancer cells