Growth Hormone (GH) and Insulin-Like Growth Factors

Question 1

Actions of Growth Hormone (GH)

Answer 1

Growth Hormone (GH):

• Made in the anterior pituitary
• Regulated by GHRH and GHIH (which are made in the cytoplasm)
• Neuroendocrine system connected to endocrine system via portal circulation

Metabolic Actions–> Goal is to increase blood glucose

Protein Metabolism:

• (-) protein anabolic
• increase AA uptake
• increase protein synthesis
• increase muscle mass

Carbohydrate Metabolism:

• Increase blood glucose
  
  • Use glucose to grow
• increase hepatic glucose output
• increase insulin resistance- helps keep glucose in the blood
• decrease glucose uptake by muscle, fat

Lipid Metabolism:

• increase lipolysis
• decrease fat syntheis
• decrease adipose mass
  
  • Amount of fat stored (bubble) decreased

Question 2

Regulation of Growth Hormone (GH)

Question 3

How does GH work?

Question 4

Clinical and/or economical applications for

GH and IGF-1.

Question 5

Diseases of GH excess and GH insufficiency

Question 6

GH is made in the _______ and regulated by the _____ and ______.

Answer 6

1. Anterior pituitary
2. GHRH- growth hormone releasing hormone
3. GHIH- growth hormone inhibiting hormone

Question 7

Growth Hormone (GH)

Answer 7

• 20,000 - 30,000 MW protein
• produced by somatotropes of the anterior pituitary
• Structure varies among species
  
  • Larger hormone = less conservation
• Travels through bloodstream & binds to GH receptors in several tissues

Question 8

Metabolic Actions of GH

(Protein Metabolism, Carbohydrate Metabolism,

Lipid Metabolism)

** Goal is to increase blood glucose**

Answer 8

Protein Metabolism:

• (-) protein anabolic
• increased AA uptake
• increased protein synthesis
• increased muscle mass

Carbohydrate Metabolism:

Question 9

Actions of IGF-1

Question 10

Stimulating GH

Answer 10

Turned “ON” by less glucose in the blood

Hypothalamus releases GHRH –>

• Anterior pituitary releases GH
  
  • moves to liver
• Liver breakdown glycogen –> glucose

Tell liver to breakdown glycogen

• By default, inhibiting insulin
  
  • Secondary default, allow blood glucose to increase
    *