Adenohypophysis Flashcards
The 3 cell types of the Adenohypophysis are?
- Acidophiles (red, most #)
- Basophiles
- Chromophobes (clear/blue)
Describe the embryology of the Adenohypophysis and what artery directly supplies it?
- derives from oral surface ectoderm (pinches off)
- None! it receives post-portal blood
What pnemonic helps remember hormones and what cell type they come from?
B-FLAT A-PiG
Basophiles: FSH, LH, ACTH, TSH
Acidophiles: Prolactin, GH
Describe Corticotropic cell products.
- produce POMC (proopiomelanocortin)
- POMC cleaved into ACTH, MSH, B-lipotrophic hormone, and endogenous opiates (B-endorphin, enkephalin)
What 2 hormones control GH release?
- GHRH from hypothalamus
- Somatostatin from hypothalamus+delta cells of pancreas
What 4 physiologic states affect GH secretion?
- blood glucose (lo gluc=incr GH)
- circadian rhythm (peaks during REM sleep)
- hi blood amino acid
- exercise
Prolactin and GH are the only two hormones from _______ cells and the only ones that use what receptor pathway?
- acidophile
- use JAK/STAT pathway (receptor-associated TYROSINE kinase); cytokines use it too
Describe the physiologic functions of Prolactin.
- stimuates milk PRODUCTION (not excretion)
- inhibits ovulation/spermatogenesis (decr. GnRH)
What are the primary regulators of PRL release?
- Inhibition: TONIC via Dopamine (hypoth)
- Stimulation: breast stimulation, TRH, estrogen
-also episodic secretion (hi night)
Name 2 classes of drug that can have immediate effects on PRL
- DA agonists (bromocriptine) for prolactinomas
- DA antagonists (most antipsychotics) and estrogens will stimulate PRL secretion
Severing the pituitary stalk will cause what effects hormonally?
PRL is the only one to go UP (tonic DA inhibition)
What 2 pharmacologic options are there for acromegaly patients?
Octreotide: somatostain analog
Pegvisomant: GHR antagonist (inhibit IGF1 prod)
How do men/women present with pituitary prolactinomas?
Men: get dry (lo libido, infertility)
Women: get juicy (amenorrhea, galactorrhea)
-all pituitary adenomas can press on optic chiasm (bitemporal hemianopsia)
Prolactinomas are first treated how?
Bromocriptine, cabergoline (DA agonists)
Describe the connection between hypothyroidism and hyperprolactinemia.
- Primary Hypothyroidism/Hashimoto’s: lo T4, thus hi TSH and TRH.
- Recall: TRH also stimulates PRL!
- therefore, will get signs/symptoms of a prolactinoma (dry men, wet women)
