Hypothalamic/Pituitary drugs: Intro and Growth Hormone Flashcards
What 4 things are the hormones of the anterior pituitary essential for?
- Regulating growth and development
- Stimulating the reproductive system
- Providing a response to stress
- Regulating intermediary metabolism
What regulates the release of anterior pituitary hormones?
Hypothalamus releasing hormones.
What inhibitory factors are released from the hypothalamus?
- Somatostatin (GH and TSH)
2. Dopamine (Prolactin)
What are the three classes of pituitary hormones?
- Somatotropic
- Glycoprotein
- Proopiomelanocortin
What hormones are in the somatotropic class?
- Growth hormone
2. Prolactin
What hormones are in the glycoprotein class?
- TSH
- LH
- FSH
(same alpha subunit, different beta subunits)
What hormones are in the proopiomelanocortin subgroup?
- ACTH
2. MSH
Why are measurements of growth hormone relatively meaningless?
Because growth hormone is secreted in a pulsatile fashion, therefore, there is a wide range of GH concentrations over the course of the day.
What factor helps medicate the effects of growth hormone?
IGF-1
What effect will blood glucose have on growth hormone secretion?
Hypoglycemia stimulates growth hormone secretion.
Hyperglycemia inhibits growth hormone secretion.
How does one test for GH deficiency?
By injecting insulin and measuring the GH response. (Insulin should cause hypoglycemia which should stimulate GH secretion)
What are some possible etiologies of GH deficiency?
Genetic deficiency
Breech/traumatic birth that damages the Anterior pituitary.
What will a newborn look like that has GH deficiency?
A newborn with GH deficiency will be normal size because GH does not effect prenatal growth.
What are the symptoms and signs of adult GH deficiency?
- Obesity
- Decreased muscle mass
- Decreased Cardiac output
Growth hormone binding activates what signal transduction pathway?
JAK2
What are the actions of Growth hormone?
- Decreased insulin sensitivity
- Increased lipolysis
- Increased protein synthesis
- Increased growth at the epiphyseal growth plate
- Increased IGF-1
What are the actions of IGF-1?
- Increased protein synthesis
2. Increased growth at the epiphyseal growth plate
Other than GH deficiency what disorders can be treated with exogenous growth hormone?
Growth hormone can be used in adults to decrease mortality from cardiovascular disease and AIDS-associated wasting (cachexia).
In children when is growth hormone treatment most effective?
Treatment is most effective in the first two years. Although treatment should be continued until growth stops.
GH exhibits what adverse effects in children?
- intracranial HTN
- visual disturbances
- headache, N/V
- Leukemia
What effects does GH exhibit in adults?
- Increased muscle and bone
- decreased fat
- peripheral edema
- Carpal tunnel
- arthralgia/myalgia
What are the three exogenous growth hormones that can be given?
- Somatropin
- Somatrem
- Semorelin
What is unique about Somatropin?
Nothing!
It is just generic hGH
What is unique about Somatrem?
Somatrem is GH with an additional methionine.
What is unique about Semorelin acetate?
Semorelin acetate is the first 29 aa of hGHRH used for the diagnosis of growth hormone deficiency. It has been discontinued.
Imagine you are a baseball player with dreams of beating Barry Bond’s single season home run record. You have decided to augment your normal regimen of anabolic steroids with hGH. Which growth hormone supplement should you probably take and why?
Semorelin would be a good choice because it usually doesn’t show up on drug tests.
What does growth hormone excess lead to?
- Gigantism (in children)
2. Acromegaly ( in adults)
What is the best treatment for GH excess?
Surgery is the best treatment for GH excess
What is Octreotide?
Octreotide is a somatostatin analog.
What sorts of adverse effects are associated with Octreotide?
GI disturbances.
What is Lanreotide?
Another somatostatin analog.
What is Pegvisomant?
Pegvisomant is a GH receptor antagonist
For what is pegvisomant used?
Pegvisomant is used clinically to treat acromegaly.
You have a patient that has the signs and symptoms of GH deficiency. However, treatment with growth hormone does not seem to be working. What is a possible alternative diagnosis?
IGF-1 deficiency. They usually also have a deficiency of IGFBP as well.
What is the treatment for IGF-1 deficiency?
Mecasermin - hIGF-1/hIGFBP-3 complex.
