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Explain GH signaling by JAK-STAT Pathway. Which other hormone uses this pathway?
GH binds to JAK-STAT receptor extracellularly. Then the intracellular domain phosphorylates multiple times. After phosphorylation, the STAT molecule dimerizes and activates transcription.
Prolactin also uses this pathway.
GH has structural resemblance to which other hormone?
Prolactin
What is JAK? What is STAT?
JAK- Janus Kinase, the enzyme that phosphorylates
STAT- signal transducer and activator of transcription
What is the Role of IGF?
anabolic and growth promoting effects
increase bone growth, mineral density, muscle mass, and differentiation of fat cells
decreases BG
What are the adverse effects of Recombinant Growth Hormone?
CANCER (neoplasms)
DECREASE INSULIN SENSITIVITY
others: peripheral edema, myalgia, arthralgia, carpal tunnel
What are the long-term complications of acromegaly?
CVD, respiratory disease, cancer
What 3 classes of agents can be used to treat acromegaly?
somatostatin analogues
dopamine agonists
GH receptor antagonists
What is the MOA of Somatostatin Analogs?
inhibit GH release from the pituitary gland
What is the MOA of Dopamine Agonists?
inhibits GH paradoxically by activating D2 receptor to inhibit prolactin release
What is the MOA of Pegvisomant?
GH receptor antagonist… AKA won’t let GH bind to target cells
What are the ADRs of Pegvisomant?
(i don’t think this is very important)
elevated LFTs, lipohypertrophy at injection site
What are the ADRs of Dopamine Agonists?
n/v, HA, postural hypotension
What is the role of dopamine in prolactin secretion?
dopamine is the molecule responsible for inhibiting the release of prolactin secretion
What are the causes of hyperprolactinemia?
ANTIPSYCHOTIC DRUGs- D2 receptor antagonists
tumors (pituitary, HT)
How would you treat hyperprolactinemia?
Dopamine agonists
What are the CNS adverse effects of Bromocriptine?
hallucinations, mood swings, psychosis, nightmare, insomnia
How does the half-life of cabergoline compare to bromocriptine?
cabergoline has longer half-live
Why is cabergoline preferred over bromocriptine?
greater efficacy, longer half life, less ADRs
Oxytocin and vasopressin are made up of a _______ amino acid peptide.
9 amino acid peptide
What causes the release of vasopressin?
low bp
high plasma osmolarity
Where are the V1a receptors located? What is their function?
located- vascular smooth muscle
function- vasoconstriction
Where are the V2 receptors located? What is their function?
located- kidneys
function- water reabsorption
True or False: V1a and V2 receptors use Tyrosine Kinase receptors.
FALSE—> use GCPRs
What are the indications for vasopressin use?
DIABETES INSIPIDUS
nocturnal enuresis
What is desmopressin?
long-acting analogue of vasopressin (ADH) with minimal V1a activity
What is an ADR of desmopressin?
hyponatremic convulsions
How is vasopressin different from desmopressin?
desmopressin does NOT cause vasoconstriction like vasopressin
What are the names of the 2 vasopressin antagonists?
conivaptan
tolvaptan
What are the MOA of each vasopressin antagonist?
conivaptan- V1a and V2 receptor antagonist
tolvaptan- V2 receptor antagonist
What is the major ADR of vasopressin antagonists?
osmotic demyelination syndrome
WHAT IS THE BOXED WARNING OF VASOPRESSIN ANTAGONISTS?
FATAL LIVER INJURY