15. Lactation and Prolactinomas Flashcards
breast development in puberty
oestrogen, progesterone
GH (via IGF-1)
increase alveolar buds and lobules
breast development in pregnancy
oestrogen, progesterone hCG, prolactin alveolar development: increased ducts and lobules differentiated secretory units colostrum accumulates
milk production: secretory initiation
progesterone
occurs during pregnancy
colostrum
milk production: sensory activation
secreted progesterone/oestrogen increased prolactin (cortisol, insulin) copious milk production after delivery (usually 2-3 days)
milk composition
sugar milk fats proteins minerals growth factors cellular factors, esp. in colostrum
sugars in milk
lactose
oligosaccharides
fats in milk
triglycerides
cholesterol
phospholipids
steroid hormones
proteins in milk
casins lactalbumin lactoferrin secretory IgA lysozyme
minerals in milk
Na+ K+ Cl- Mg2+ PO4-
cellular components in milk
macrophages lymphocytes neutrophils epithelial cells phospholipids
lactation
galactopoiesis
positive feedback
regular removal of milk, nipple stimulation
prolactin (from ant pituitary), oxytocin (from post pituitary)
prolactin
secreted by lactotroph cells in anterior pituitary
similar GH with similar receptor (tyrosine phosphorylation, JAK-STAT)
release is inhibited by dopamine
release is stimulated by serotonin, TRH and oxytocin
lactational amenorrhoea
contraceptive efficacy depends on frequency and duration of breast feeding
what can increased prolactin cause?
decreased GnRH
decreased LH and FSG (decreased pulsatility)
decreased oestrogen/testosterone
oxytocin
nonapeptide
synthesised in hypothalamic magnicellular neurons
released from posterior pituitary
neurosecretory granules released into capillary system of post pituitary
roles of oxytocin
uterine myometrial contraction at birth
smooth muscle activation in breast
milk let down: role in maternal behaviour?
evolutionary perspective of lactation
mammals lactate: production of nutritious secretion from an exocrine gland
continued nurture of offspring after birth - enhanced brain development
hyperprolactinaemia presentation in women
oligo/amenorrhoea
galactorrhoea
subfertility
may not have all symptoms
hyperprolactinaemia presentation in men
erectile duysfincttion decreased libido visual symptoms, headaches hypopituitarism galactorrhoea/gynaecomastia
causes of hyperprolactinaemia
physiological - pregnancy, lactation
hypothalamic-pituitary disease (prolactinoma, non-functioning adenoma)
drugs
stress
other - PCOS, hypothyroidism, renal failure, cirrhosis
drugs increasing prolactin secretion
antidepressants
antipsychotics
drugs for nausea/vertigo (phenothiazines, metoclopramide)
drug mechanisms for increasing prolactin secretion
inhibition of secretion/action of dopamine
stimulation of central serotonin pathways
hyperprolactinaemia investigations
pregnancy test renal function liver function tests thyroid function prolactin LH, FSH testosterone MRI pituitary
aims of hyperprolactinaemia treatment
restore fertility
stop galactorrhea
restore regular menstrual periods/libido
shrink tumour
