Anterior Pituitary

Question 1

What hypothalamic neurons project their axons into the median eminence?

Answer 1

Parvicellular neurons (the posterior pituitary is associated with magnocellular neurons).

Question 2

What are the three classes of anterior pituitary hormones?

Answer 2

Glycoproteins, POMC, and growth hormone/prolactin.

Question 3

What AP hormones are glycoproteins?

Answer 3

TSH, FSH, and LH.

Question 4

What defines the AP glycoprotein hormones?

Answer 4

They have a common alpha subunit but unique beta subunits that confer biological specificity.

Question 5

What are the POMC (pro-opiomelanocortin) AP hormones?

Answer 5

ACTH, MSH, and beta-endorphins.

Question 6

What are GH and prolactin structurally similar to?

Answer 6

Human placental lactogen.

Question 7

What GPCR type does TRH bind to on thyrotrophs?

Answer 7

Gq receptors.

Question 8

What GPCR type does TSH bind to on thyroid follicular cells?

Answer 8

Gs receptors.

Question 9

What GPCR type does GnRH bind to on gonadotrophs?

Answer 9

Gq receptors.

Question 10

What GPCR type does FSH and LH bind to on target cells?

Answer 10

Gs receptors.

Question 11

What GPCR type does CRH-1 bind to on corticotrophs?

Answer 11

Gs receptors.

Question 12

What does CRH-1 stimulate?

Answer 12

POMC synthesis, release, and processing.

Question 13

What GPCR type does ACTH bind to on adrenal cortical cells?

Answer 13

Gs receptors.

Question 14

What is the specific receptor that ACTH binds to?

Answer 14

Melanocortin 2 receptor (MC2R) as opposed to MC1R for MSH.

Question 15

What GPCR type does GHRH bind to on somatotrophs?

Answer 15

Gs receptors.

Question 16

What GPCR does somatostatin bind to on target cells?

Answer 16

Gi receptors.

Question 17

What GPCR does dopamine bind to on lactotrophs?

Answer 17

Gi receptors (dopamine D2 receptors).

Question 18

What are the sources of somatostatin in the hypothalamus?

Answer 18

The periventricular nucleus, arcuate nucleus, and ventromedial nucleus.

Question 19

What is the common thread with the hypothalamic releasing and inhibiting factors?

Answer 19

They all work through G-coupled receptors (TRH and GnRH through Gq, GHRH and CRH through Gs, and dopamine and somatostatin through Gi).

Question 20

What receptors do TSH, ACTH, and FSH/LH act through on target organs?

Answer 20

G-coupled receptors.

Question 21

What receptors do GH and prolactin act through on their target organs?

Answer 21

Cytokine receptors (tyrosine kinase receptors). (remember these receptors act through auto-phosphorylation upon ligand binding).