Endocrine GH and Prolactin (Welch) Flashcards
What is the only place Growth Hormone binds as unchanged growth hormone?
- Fat tissue
- Muscle tissue
- Liver
What does the binding of GH in fat tissue cause?
- Decrease glucose uptake
- Increase lipolysis
- Overall decrease Adiposity
What does the binding of GH in the muscle tissue cause?
- Decrease glucose uptake
- Increase amino acid uptake
- Increase protein synthesis
- Overally increase lean body mass
What are 5 things that increase when GH binds to Liver?
- RNA Synthesis
- Protein Synthesis
- Gluconeogenesis
- Insulin-like growth factor binding protein (IGFBP)
- Insulin-like growth factor
The insulin like Growth Factors (IGF) produced by the liver and excreted to the rest of the body have what general effect on the lungs, heart, and bone?
- Increase organ size
2. Increase organ function
he insulin like Growth Factors (IGF) produced in the liver and excreted to the rest of the body have what general effect on the chondrocytes?
Increase linear growth
What does IGF specifically increase in the lungs heart and bone that results in increased organ size and organ function?
- increase protein synthesis
- Increase RNA synthesis
- Increase DNA synthesis
- Increase cell size
- Increase cell number
What does IGF specifically do in the chondrocyte to give the overall effect of increase in linear growth?
increase amino acid uptake Increase protein synthesis Increase RNA synthesis Increase DNA synthesis Increase collagen Increase chondroitin sulfate Increase cell size Increase cell number
What starts the cascade for the release of Growth hormone?
Growth hormone releasing hormone (GHRH) from hypothalamus
Onto what structure is GHRH from hypothalamus released and what is subsequently released?
Anterior pituitary Growth Hormone (GH) release
What inhibits GH production?
Somatostatin
What is a growth hormone releasing hormone analogue used as a diagnosis for idiopathic growth hormone deficiency in order to characterize pituitary responsiveness?
Sermorelin
GHRH44
When is Growth hormone most active?
Sleep
More active in youth
What does GH do for metabolism?
Converts body over for lipolysis for energy during times of fasting
What can stimulate Growth Hormone releasing hormone?
- Exercise
- Stress
- Sleep
- Excitement
- Insulin
Increased in Growth hormone causes release of what else?
GHRIH
Besides the excretion of Growth Hormone, what else stimulates Growth Hormone Release Inhibiting Hormone?
- FFA
- Hyperglycemia
- Glucagon
- ACTH
- Glucocorticoids
What is the only Growth Hormone inhibitor?
Somatostatin
What are 3 pharmacological effects of Somatostatin (GHRIH)?
- inhibits secretion of insulin and glucagon from pancreas
- Inhibits gastrin secretion from pancreas
- Inhibits secretion of TSH, ACTH
Somatostatin (GHRIH) inhibition of secretion of insulin and glucagon from pancreas leads to what?
increase in FFA and decrease in glucose
Long acting Somatostatin (GRHIH) analogue to treat acromegaly and as a full body scan to look for tumors growing in the body?
Octreotide
Why would a somatostatin analogue be used to scan for tumors?
Because most tumors have GH
What is a better treatment for Acromegaly to suppress high levels of GH?
Bromocryptine (DA agonist)
Is GH high or low in Diabetes mellitus patient?
High. If insulin is low, GH is high converting fats to glucose for energy
What will GHRIH (somatostatin) given to a Type I diabetic help prevent ?
Ketoacidosis
What part of Growth Hormone (Somatotropic / GH) binds to one of the 3 receptors in the body for GH?
Only the active one
The following are characteristics of what GH excess :
Osteoarthritic vertebral changes
Visual field changes (bitemporal hemianopia) Prognathism
Hirsutism
Gynecomastia and lactation
Enlarged hands and feet
Acromegaly
What are 4 ways to slow or stop GH release from anterior pituitary at the anterior pituitary?
- Surgery
- Radiotherapy
- Dopamine agonists
- Somatostatin analogues
What can you use to slow GH from releasing IGF from liver, or acting directly on adipose tissues or muscle?
GH Receptor Antagonists
For GH active core to stimulate its receptor what must occur?
GH site A and GH site B must bind to their individual receptor site which pull together to form a dimer
Once the GH active core has dimerized what must occur for it to act on its target cell?
Must anchor into the plasma membrane
What does the dimerized active core Growth hormone do once it is inserted into the cell membrane?
Stimulates tyrosine kinase that will eventually cause transcription factors to express genes
Are the anabolic and growth promoting effects of growth hormone due to growth hormone itself or IGF-1?
IGF-1
Is GH a hyperglycemia or hypoglycemic inducing drug?
Hyperglycemic drug. Will increase blood sugar.
What is the metabolic effect of GH on proteins?
Anabolic
What is the metabolic effect of GH on fat?
Lipolysis in adipose tissue
What is the metabolic effect of GH on carbohydrates?
Hyperglycemia, if given long-term
What is the metabolic effect of GH on calcium?
Lipolysis in adipose tissue
IGF-1 binds to what type of receptor?
Looks like half of an insulin like receptor and is associated with tyrosine kinases
IGF-1 promotes growth in every organ except what 2?
- Brain
2. Eye
IGF-1 will promote growth in long bones until when?
Until epiphyseal plates close
What is retained during protein synthesis caused by IGF-1?
Nitrogen
IGF-1 stimulate the uptake of what compound into cartilage
Sulfate
What is the main difference between GH and insulin?
Insulin does not induce lipolysis
GH will increase blood sugar level
What are 2 substances that antagonize GH and insulin?
- Glucocorticoids
2. Catecholamines
Insulin and GH both do what with respect to sugar?
Promote sugar storage
Can GH antagonize Insulin?
Yes
In a diabetic with low insulin, what will be elevated to account for the inability of the body to use glucose for energy?
Increase growth hormone, and increase glucagon
In a non-diabetic how do Insulin and GH work?
Work in opposition based on sleep cycle, but both work to store glucose as glycogen
Why are Type I diabetic children not extremely tall seeing as they have a higher than average level of growth hormone to compensate for their lack of insulin?
Because their epiphyseal plates will close with increased GH, and they can only grow when epiphyseal plates are open
What will happen in a person lacking GH ?
Glucose will be used up too rapidly
What will be induced if a normal adult is taking GH for enhancement?
Diabetes
Can GH be administered orally?
No. It is a peptide.
What is the only clinical use for administration of human pituitary GH?
Hypopituitary dwarf with open epiphyseal plates
Of the 2 synthetic GH used for the treatment of hypopituitary dwarfism or GH-deficient patients with hypoglycemia, which drug is longer acting: Somatrem or Somatropin?
Somatrem
Patients on GH replacement therapy (Somatrem or Somatropin) should be evaluated yearly for what side effect?
Hypothyroidism
What is an anterior pituitary hormone that is structurally similar to GH (Its levels rise during pregnancy and reach maximum levels at term)?
Prolactin
What are 2 hormonal controls of Prolactin release from anterior pituitary?
Prolactin Releasing hormone (PRH)
Thyrotropic Releasing hormone (TRH)
What is the stimulation in nursing mothers for prolactin?
Suckling
Why is it thought that prolactin decreases chance of getting pregnant in a nursing mother?
Prolactin decreases leutenizing hormone (LH) and Follicle stimulating hormone (FSH)
What 2 things that cause the release of Prolactin Release Inihibiting Hormone?
Dopamine and dopamine agonists
What treatment would be indicated to stop lactation?
Prescribe dopamine agonist to increase PRIH
What blocks the action of prolactin during pregnancy?
Estrogen and progesterone
What does prolactin do in the mammary glands?
Promoting proliferation and differentiation of mammary ductal and alveolar epithelium
What effect does prolactin have on the ovaries and gonads?
Inhibits LH and FSH release and their action on the ovaries or gonads
What is the most common physiologic condition causing hyperprolactinemia?
Pituitary tumor
What are other causes of hyperprolactinemia?
- Dopamine antagonist (reserpine)
- Goiter causing increased TRH
- Oral contraceptives (will increase TRH)
What are 5 consequences of hyperprolactinemia?
- Galactorrhea
- Amenorrhea
- Infertility
- Impotence
- Possibly mammary tumors
What is the drug of choice for the treatment of hyperprolactinemia?
Bromocriptine, a dopamine agonist (ergot alkaloid)
What is a side effect of bromocriptine?
Postural hypotension due to systemic vasoconstriction
Is bromocriptine for the treatment of hyperprolactinemia orally active?
Yes
In what patient population is bromocriptine contraindicated?
Pregnancy. Ergot alkaloid will induce abortion.
Estrogens and progesterone are regulators of what hormone?
Prolactin