Anterior Pituitary Flashcards
What hypothalamic neurons project their axons into the median eminence?
Parvicellular neurons (the posterior pituitary is associated with magnocellular neurons).
What are the three classes of anterior pituitary hormones?
Glycoproteins, POMC, and growth hormone/prolactin.
What AP hormones are glycoproteins?
TSH, FSH, and LH.
What defines the AP glycoprotein hormones?
They have a common alpha subunit but unique beta subunits that confer biological specificity.
What are the POMC (pro-opiomelanocortin) AP hormones?
ACTH, MSH, and beta-endorphins.
What are GH and prolactin structurally similar to?
Human placental lactogen.
What GPCR type does TRH bind to on thyrotrophs?
Gq receptors.
What GPCR type does TSH bind to on thyroid follicular cells?
Gs receptors.
What GPCR type does GnRH bind to on gonadotrophs?
Gq receptors.
What GPCR type does FSH and LH bind to on target cells?
Gs receptors.
What GPCR type does CRH-1 bind to on corticotrophs?
Gs receptors.
What does CRH-1 stimulate?
POMC synthesis, release, and processing.
What GPCR type does ACTH bind to on adrenal cortical cells?
Gs receptors.
What is the specific receptor that ACTH binds to?
Melanocortin 2 receptor (MC2R) as opposed to MC1R for MSH.
What GPCR type does GHRH bind to on somatotrophs?
Gs receptors.
What GPCR does somatostatin bind to on target cells?
Gi receptors.
What GPCR does dopamine bind to on lactotrophs?
Gi receptors (dopamine D2 receptors).
What are the sources of somatostatin in the hypothalamus?
The periventricular nucleus, arcuate nucleus, and ventromedial nucleus.
What is the common thread with the hypothalamic releasing and inhibiting factors?
They all work through G-coupled receptors (TRH and GnRH through Gq, GHRH and CRH through Gs, and dopamine and somatostatin through Gi).
What receptors do TSH, ACTH, and FSH/LH act through on target organs?
G-coupled receptors.
What receptors do GH and prolactin act through on their target organs?
Cytokine receptors (tyrosine kinase receptors). (remember these receptors act through auto-phosphorylation upon ligand binding).
