Exam 2 (Lecture 4) - Growth Hormone

Question 1

What is the chemical nature of the growth hormone and which gland secretes it? Which other tissue is capable of the GH secretion?

Answer 1

1) Protein hormone secreted by somatotrophs of the anterior pituitary

2) Mammary glands can also secrete smaller amounts in cats, dogs, and humans

Question 2

What are the two main functions of GH?

Answer 2

1) Promotes growth

2) Provides ready source of energy during starvation

Question 3

Explain the indirect, growth-promoting action of GH and the role of IGF-1 in this process.

Answer 3

1) GH stimulates liver to secrete IGF-1

2) IGF-1 is related to insulin, hence the name (insulin-like growth factor)

3) IGF-1 stimulates lipogenesis, protein synthesis, cell multiplication, cell enlargement, and also the deposition of extracellular matrix.

Question 4

Explain anti-insulin GH actions.

Answer 4

During starvation or in poorly fed animals, GH stimulates gluconeogenesis in the liver and lipolysis in the adipose tissue. This leads to glucose and FAs/glycerol being released into the bloodstream. (This activity could potentially lead to diabetes due to the extra glucose and FAs in the blood).

Question 5

What are gigantism and acromegaly, and which factor decides which of these two conditions develops?

Answer 5

1) Gigantism and acromegaly are both forms of hypersomatotropism, which is a high level of GH being present.

2) The timing of the excess GH (before or after the epiphyseal closure) determines which condition develops.
- Before = Gigantism
- After = Acromegaly

Question 6

What is pituitary dwarfism?

Answer 6

Pituitary dwarfism is hyposomatotropism (low level of GH present)
- failure to secrete enough of the GH in young animals (Grumpy Cat)

Question 7

Why could a treatment with progestins in older female dogs lead to acromegaly and secondary diabetes mellitus?

Answer 7

Progestin may promote hypersecretion of GH.

GH, in turn, has anti-insulin actions such as stimulation of lipolysis and gluconeogenesis. These processes could lead to excess FAs and glucose in the bloodstream and ultimately diabetes mellitus.

Question 8

Is the pork meat from animals regularly supplements with porcine GH healthy for human consumption?

Answer 8

ANY hormone use in pork is prohibited by federal law.

Question 9

Is the use of the recombinant bST for increasing cow milk production legal in the U.S. and Canada?

Answer 9

US = Yes

Canada = No