Hypothalamic & Pituitary Hormones Flashcards
Receptor for GH and prolactin?
JAK/STAT superfamily
Drugs that mimic or block the effects of hypothalamic and pituitary hormones have pharmacologic applications in three main areas:
- Replacement therapy for hormone deficiency states
- Antagonist for diseases that result from excess production of hormones
- Diagnostic tools for identifying endocrine abnormalities
GPCRs are receptors for what hormones?
- TSH
- FSH
- LH
- ACTH
GH, somatotropin
- Hypothalamic hormone?
- Target organs?
- Primary target organ hormone or mediator?
- GHRH (+), stomatostatin (-)
- liver, muscle, bone, kidney, and others
- insulin-like growth factor 1 (IGF-1)
TSH
- Hypothalamic hormone?
- Target organs?
- Primary target organ hormone or mediator?
- TRH (+)
- thyroid
- thyroxine, triiodothyronine
Adrenocorticotropin (ACTH)
- Hypothalamic hormone?
- Target organs?
- Primary target organ hormone or mediator?
- CRH (+)
- adrenal cortex
- glucocorticoids, mineralcorticoids, androgens
Follicle-stimulating (FSH) and Luteinizing hormone (LH)
- Hypothalamic hormone?
- Target organs?
- Primary target organ hormone or mediator?
- GnRH (+)
- gonads
- estrogen, progesterone, testosterone
Prolactin (PRL)
- Hypothalamic hormone?
- Target organs?
- Primary target organ hormone or mediator?
- dopamine (-)
- breast
Growth Hormone (somatotropin)
Pharmacodynamics?
mediates effects via cell surface receptors that activate JAK/STAT signaling cascades.
binds to two tyrosine receptors -> dimerizes -> self phosphorylate -> signaling cascade -> upregulate genes
(slow effect b/c requires gene expression)
Growth Hormone (somatotropin)
Physiological effects?
- stimulation of longitudinal growth of bones
- increased bone mineral density
- increased muscle mass (in GH deficient people)
- increased GFR
- stimulation of preadipocyte differentiation into adipocytes
- anti-insulin actions (decreased glucose utilization and increased lipolysis)
- development and increased function of immune system
7.
Growth Hormone (somatotropin)
Clinical pharmacology?
- Growth hormone deficiency
- genetic or damage to pituitary or hypothalamus
- short stature and adiposity (in children)
- hypoglycemia (unopposed insulin action) - criteria for diagnosis
- a growth rate < 4cm per year
- the absence of a serum GH response to two GH secretagogoues.
Growth Hormone (somatotropin)
recombinant form?
- somatropin = recombinant GH
2. somatrem = GH analog
Growth Hormone (somatotropin)
clinical condition?
- Growth failure in pediatric pts associated with:
1. GH deficiency
2. chronic failure
3. noonan syndrome
4. Prader-Willi syndrome
5. short stature homeobox-containing gene deficiency
6. Turner syndrome
7. small for gestational age with failure to catch up by age 2
8. idiopathic short stature in pediatric pts - Growth hormone deficiency in adults
- wasting in HIV + pts
- short bowel syndrome in pts who are receiving specialized nutritional support
Growth Hormone (somatotropin)
Primary therapeutic objective?
- growth
- Improved metabolic state, increased lean body mass, sense of well-being, weight, and physical endurance
- improved GI function
Growth Hormone (somatotropin)
Adverse effects in children?
- scoliosis (during rapid growth)
- hypothyroidism
- intracranial HTN
- otitis media (increased risk for turner)
- pancreatitis, gynecomastia, nevus growth
- diabetic syndrome (chronic use)
Growth Hormone (somatotropin)
Adverse effect in adults?
- peripheral edema, myalgias and arthralgias (hands/wrists)
- carpal tunnel syndrome
- proliferative retinopathy (rare)
Growth Hormone (somatotropin)
Contraindications?
CYP450 inducer
patients with a known malignancy
IGF-1 Analog - mecasermin
uses?
- IGF-1 deficiency in children
- causes: mutations in gene that encodes for GH receptor and development of neutralizing antibodies to GH.
IGF-1 Analog - mecasermin
Adverse effects?
- hypoglycemia (eat 20min before or after admin)
- intracranial HTN
- asx elevation of liver enzymes
sx’s of GH secreting tumors?
- commonly in adults
- sx’s:
1. acromegaly (abnl growth of cartilage, bone tissue, skin, muscle, heart, liver and GI tract)
2. giantism (if occurs before long bone epiphyses close)
GH hormone secreting tumors - tx?
GH antagonists for small adenomas:
- GH receptor antagonists
- somatostatin analogs
- dopamine receptor agonists
Large adenomas require surgery or radiation
Pegvisomant?
GH receptor antagonist
Octreotide?
somatostatin analog.
inhibits release of GH, TSH, glucagon, insulin, and gastrin
Octreotide
Pharmacokinetics?
45x more potent in inhibiting GH release than somatostatin
Octreotide acetate = long-acting suspension can be given at 4 week intervals.
Octreotide
Clinical applications?
reduces sx’s caused by hormone-secreting tumors
localizing neuroendocrine tumors
acute control of bleeding from esophageal varices.
Octreotide
Adverse effects?
nausea, vomiting, abd cramps, flatulence, steatorrhea
constipation
biliary sludge and gallstones
sinus bradycardia and conduction distubances
vit B12 deficiency
pain at injxn site = common
Bromocriptine and Cabergoline?
dopamine agonists