Prolactin regulation and dopaminergic control
Core concept
- *Prolactin is the only anterior pituitary hormone under tonic INHIBITORY hypothalamic control*
- Dopamine from tuberoinfundibular neurons -> portal circulation -> D2 receptors on lactotrophs -> suppresses prolactin
- Stimulatory inputs are secondary: TRH, VIP, oestrogen, serotonin, oxytocin, suckling, stress, sleep
- -> anything that cuts the stalk removes the brake
- Stalk lesion / "stalk effect": PROLACTIN RISES while every other anterior pituitary hormone FALLS
- This is the single most useful discriminator between a prolactinoma and a non-functioning mass compressing the stalk
- Prolactin inhibits GnRH pulsatility -> dec LH/FSH -> hypogonadotropic hypogonadism
- Women: oligo/amenorrhoea, galactorrhoea, infertility, dec libido, osteoporosis
- Men: dec libido, erectile dysfunction, infertility, gynaecomastia; galactorrhoea is uncommon in men
3 more sections, plus exam facts
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