Hypothalamus-Pituitary hormones

Question 1

Where is prolactin secreted from?

Answer 1

anterior pituitary

Question 2

What is the function of prolactin?

Answer 2

Stimulates milk production in the breast, inhibits ovulation in females and spermatogenesis in males by inhibiting GnRH synthesis and release.

Question 3

What inhibits prolactin release?

Answer 3

• Dopamine from hypothalamus.
• Prolactin self-inhibits by increasing dopamine synthesis in hypoT.
• Dopamine agonists inhibit prolactin secretion

Question 4

What stimulates prolactin release?

Answer 4

TRH increases prolactin secretion. 
Dopamine antagonists (eg most antipsychotics) and estrogens (OCPs, pregnancy) increase prolactin secretion.

Question 5

Where is growth hormone secreted from?

Answer 5

released in pulses from anterior pituitary

Question 6

What stimulates secretion of growth hormone? When does this typically happen?

Answer 6

GHRH. GHRH is secreted during exercise, sleep, hypoglycemia states.
Ghrelin also stimulates GH release via GH secretagog receptor.

Question 7

What inhibits secretion of GH?

Answer 7

• Somatostatin inhibits GH
• GH itself provides negative inhibition on hypothalamus, decreased GHRH.
• IGF-1 inbhits both GH and GHRH

Question 8

What is the function of GH?

Answer 8

Stimulates linear growth and muscle mass through IGF-1 secretion.
Increases insulin-resistance (diabetogenic).

Question 9

Why is serum GH not a good measurement?

Answer 9

Half life is 6-20 mins. IGF-1 is better to measure.

Question 10

What does CRH do? Where is it secreted from?

Answer 10

Stimulates ACTH, MSH, and Beta-endorphin. Hypothalamus.

Question 11

What does Dopamine do?

Answer 11

decrease prolactin secretion

Question 12

What does GHRH do?

Answer 12

Increase GH

Question 13

What does GnRH do?

Answer 13

Increase FSH and LH when pulsatile, suppress when tonic

Question 14

What hormone does prolactin suppress secretion of?

Answer 14

GnRH

Question 15

What does somatostatin do at the pituitary level?

Answer 15

Decrease GH, and TSH.

Question 16

What does somatostatin do at the pancreas?

Answer 16

Inhibit glucagon and insulin

Question 17

Where else are somatostatin receptors found?

Answer 17

GI tract

Question 18

What does TRH do?

Answer 18

Increases TSH secretion, increases prolactin secretion

Question 19

Where is ADH synthesized and secreted?

Answer 19

Synthesized in hypothalamus (supraoptic nuclei), released by posterior pituitary.

Question 20

What two receptors does ADH interact w/?

Answer 20

V1 and V2

Question 21

What does stimulation of V1 receptors by ADH do?

Answer 21

Increase blood pressure.

Question 22

What does stimulation of V2 receptors by ADH do?

Answer 22

Regulates serum osmolarity; ADH decreases serum osmolarity and decreases urine osmolarity.

Question 23

How do V2 receptors/ADH decrease serum osmolarity?

Answer 23

Increase expression of aquaporin channels in principal cells of renal collecting duct –> bring in more water.

Question 24

What is the defect in central diabetes insipidus?

Answer 24

Decreased ADH level.

Question 25

What is desmopressin?

Answer 25

An ADH analog that can be given as treatment for central DI.

Question 26

What does a mutation in the V2 receptor cause?

Answer 26

nephrogenic diabetes insipidus.