GH & PRL - Trachte

Question 1

GHIH (Growth hormone inhibitory hormone) is the same as…..

Answer 1

SOMATOSTATIN

Inhibits GH release

Question 2

What two hormones are secreted from the hypothalamus in regards to GH?

Answer 2

GHRH

GHIH (Somatostatin)

Question 3

There are 5 somatostatin receptors…. what kind of receptor are they?

Answer 3

Gi-coupled receptor
Decrease cAMP
Activate K+ channels

Question 4

Aside from somatostatin what neurotransmitter can inhibit GH release?

Answer 4

Dopamine

Question 5

What type of receptor is the GHRH receptor?

Answer 5

Gs-coupled receptor
Stimulates adenylyl cylcase
Increases cAMP

Question 6

What cells in the anterior pituitary produce GH?

Answer 6

Somatotropes

Question 7

GHBP binds GH in the serum… GHBP also indicates tissue levels of GH receptor… why is that?

Answer 7

GHBP is the ectodomain of the GH receptor, which is solubilized

Question 8

What type of receptor does GH bind on target tissues?

Answer 8

Cytokine receptor (with tyrosine kinase activity) that activates JAK/STAT second messenger signal transduction pathway

this is how all “growth factor receptors” work!!!!*

Question 9

What are the final hormones mediating GH Axis effects?

Answer 9

Growth Hormone

IGF-1

Question 10

What organ produces IGF-1 after being stimulated by GH?

Answer 10

The liver!

Question 11

How does GH affect serum glucose?

Answer 11

Diabetogenic! Causes hyperglycemia due to decreased insulin sensitivity

Question 12

How does IGF-1 affect serum glucose?

Answer 12

Hypoglycemia

It has insulin like activity

Question 13

Is IGF-1 or GH better at stimulating chondrogenesis at epipyseal growth plates in children?

Answer 13

IGF-1

Question 14

What stimulates GHIH release?

Answer 14

IGF-1 (negative feedback!)

Question 15

What is Sermorelin?

Answer 15

GHRH analog

Question 16

What is Laron-type Dwarfism?

Answer 16

GH receptor variant which has weak binding to GH

Results in LOW IGF-1 levels

Autosomal recessive, present at birth

Question 17

What determines if hypersecretion of GH will result in gigantism or acromegaly?

Answer 17

Determined by timing of epiphyseal plates closure

Hypersecretion in adults - leads to acromegaly

Question 18

What is the first indication of GH hypersecretion?

Answer 18

Elevated IGF-1

Question 19

What is the primary treatment for GH hypersecretion?

Answer 19

Somatostatin analogues (Octreotide)

Dopamine Agonists (D2) = Bromocriptine

Question 20

What is bromocriptine?

Answer 20

Dopamine agonist used to treat GH hypersecretion

Question 21

What is Octerotide?

Answer 21

Somatostatin analogue used to treat GH hypersecretion

Question 22

What is Pegvisomant?

Answer 22

Growth Hormone receptor antagonist used to treat GH hypersecretion

**basically binds GHR and is so big, that it doesn’t let the cross phosphorylation happen…. neato!

Question 23

What is needed for a clinical diagnosis of GH hyposecretion?

Answer 23

GnRH-arginine costimulation test (should raise GH levels)

or

Insulin tolerance test (induces hypoglycemia which should stimulate GH)

Question 24

What is the primary inhibitory factor for prolactin?

Answer 24

Dopamine! (D2 receptors)

Question 25

Is prolactin primarily under stimulatory or inhibitory control?

Answer 25

Inhibitory!! Prolactin releasing hormone is "hypothetical"

Question 26

What cells produce and secrete prolactin?

Answer 26

Mammotrophs

Question 27

What happens to prolactin if you block the hypophyseal portal system?

Answer 27

IT GOES UP!!!!! (because it is under inhibition!)

Question 28

Does prolactin stimulate milk production or secretion?

Answer 28

PRODUCTION!

Question 29

What kind of receptor is the prolactin receptor?

Answer 29

Tyrosine kinase!

Question 30

Does prolactin participate in a negative feed back loop?

Answer 30

Nope!

Question 31

What would you use to treat a hyperprolactinemia tumor?

Answer 31

Dopamine agonists! Cabergoline Bromociptine

Question 32

What is Cabergoline?

Answer 32

Dopamin agonist! Used to treat hyperprolactinemia tumor **preferred to other dopamine agonists because it has higher efficacy in normalizing prolactin levels, and higher frequency of tumor shrinkage! NEAT