PROLACTIN IN MAMMALSBy: 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.

• Peptide-based

• It is a pituitary polypeptide

• Alpha helix folded

BASE

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