Growth Hormone

Question 1

What do growth hormone experiments show us?

Answer 1

That growth hormone is not required for in utero development.

Question 2

Give some background to growth hormone.

Answer 2

Single chain polypeptide - 191 AAs, 21 kDa

High structural homology with pro
actin and PL

Species specific

Max secretion during puberty.

Question 3

What is Laron syndrome?

Answer 3

mutated GH receptor --> resistance 
Impaired post natal growth 
low plasma IGF-1 
High plasma Gh (no IGF-1) negative feedback on somatotrophs
teat with IGF-1 injections.

Question 4

Differentiate between IGF1 gene deletion and receptor defects.

Answer 4

former has some growth therefore must be IGF1 independent mechanisms

latter is embryonically lethal as IGF-1R plays key role in embryonic development.

Question 5

What is the half life of growth hormone?

Answer 5

50 mins

Question 6

What are the effects of IGF1?

Answer 6

Increase protein synthesis

Cartilage formation and bone growth

Organ growth rate

Question 7

What causes gigantism and how can it be treated?

Answer 7

Over secretion of GH pre puberty (pituitary adenoma and expansion of somatotrophs)

Surgical removal or somatostatin analogue administration.