Growth Hormone, IGF-1 and Skeletal Growth

Question 1

What is the effect of high does of glucocorticoids on osteoblasts?

Answer 1

High does glucocorticoids inhibit osteoblats thus promoting bone reabsorption.

Question 2

Role of Ihh

Answer 2

Ihh helps form the bony collar

Feedsback on PTHrP to promote proliferation

Question 3

Master Regulator of Bone growth and differentiation

Answer 3

RunX2

Question 4

What is the effect of FGF-18 binidng to FGF-R?

Answer 4

FGF-18 binding to FGF-R inhibits chondrocyte proliferation

nb: Overactive FGF-R linked to dwarfism

Question 5

When is IGF-1 important?

Answer 5

Late in gestation

nb: IGF-1 is GH INDEPENDENT

Question 6

What is the relationship between IGF-1 and GH

Answer 6

IGF-1 becomes under GH control shortly after birth

Question 7

What cell in the anterior pituitary produce Growth Hormone?

Answer 7

Somatotropes

Question 8

What is the major negative feedback protein of the GH axis?

Answer 8

IGF-I

Question 9

In the fasted state, what is different about GH production?

Answer 9

In the fasted state, GH does not induce production of IGF-I

Question 10

Mechanism of GH Signaling

Answer 10

GH binds to a Jak/STat Receptor
Activates STAT5b
STAT5b leads to transcription of SOCS and IGF-I
SOCS inhibits GH Receptor

Question 11

In regards to GH signaling, what is the ternary complex produced by the liver?

Answer 11

IGF-I, IGF-BP3 and ALS

Question 12

Four major factors of bone determined by sex hormones

Answer 12

1. Promote longitudinal bone growth at the onset of puberty
2. Stimulate periosteal apoosition
3. Closure of epiphysis at the end of puberty
4. Maintenance of adult bone mass

Question 13

Closure of epiphysis plate is mediate by which receptor?

Answer 13

Estrodiol Receptor Alpha (ER-Alpha) in both men and women?