Exam #02 (Steroids) Flashcards
List the intermediates in the biosynthesis of cholesterol.
(1) Acetyl-CoA + acetoacetyl-CoA (hydrated to form) HMG-CoA (reduced to form) Mevalonate (converted to) Isoprene units (3 units condense to form) Cholesterol
Give the hierarchy of where glucocorticoids, mineralocorticoids, and androgens are derived?
Cholesterol –> Pregnenolone –> Progesterone –> (Glucocorticoids + Mineralocorticoids + Androgens)
Pregnenolone can be converted to what major secretory product of the androgens?
DHEA (Dehydroepiandrosterone)
Testosterone can be converted to what major secretory product of the androgens via 5alpha-reductase?
DHT (Dihydrotestosterone)
Important in controlling prostate and hairgrowth
What enzyme converts testosterone to estradiol?
Aromatase
Progesterone can be converted into what (2) major secretory products in the glucocorticoids and mineralocorticoids?
Glucocorticoids: Cortisol (HYDROcortisone)
Mineralocorticoid: Aldosterone
LH stimulates the release of what (2) steroids?
- androgens
2. progestins
FSH stimulates the release of what steroid?
esterogen
Chorionic gonadotropin (HCG) stimulates the release of what steroid?
progestins
Name the (3) regions of the adrenal cortex and which steroid(s) produced in each region.
- Zona glomerulosa - produces mineralocorticoids (aldosterone)
- Zona fasciculata - produces glucocorticoids (cortisol, cortisone)
- Zona reticularis - produces sex hormones (androgens)
Renin/angiotensin stimulates the release of what steroid?
mineralocorticoids (aldosterone)
True or False - The MOA of steroids is based soley on having a “genomic” mechanism in which binding of steroids to glucocorticoid receptors interacts with the transcription of target genes?
False - steroids have a “genomic” mechanism that accounts for the long term effects, and also a non-genomic MOA involving 7TM-GPCR responsible for the rapid response of steroids
What component of a steroid receptor is involved with the correct fitting of steroids into the receptor?
Zn fingers
Cortisol can exist as free cortisol in plasma and protein-bound cortisol in plasma. Which protein does cortisol primarily bind to?
corticosteroid-binding globulin (CBG) also called transcortin
True or False - synthetic steroids are highly protein bound?
True - synthetic steroids are highly bound to albumin
What are the (3) main routes glucocorticoids are metabolized?
- oxidation
- glucuronidation
- sulfation
*glucocorticoids are highly metabolized
Describe the pathway leading to the release of cortisol initiated by trauma via nociceptive pathways, drive for circadian rhythm, or emotion via the limbic system?
Initiation of the pathway stimulates the Hypothalamus to release CRH which stimulates the Anterior Pituitary to release ACTH which stimulates the Adrenal Cortex (Zona Fasciculata) to release cortisol
CRH = corticotropin releasing hormone ACTH = adrenocorticotropic hormone
Describe the negative feedback mechanism of cortisol.
Release of cortisol by the adrenal cortex has a negative feedback mechanism. Cortisol inhibits the hypothalamus and anterior pituitary from releasing stimulating hormones (CRH and ACTH, respectively) to cause the adrenal cortex to release more cortisol
Cushing’s syndrome describes the signs and symptoms associated with prolonged exposure to inappropriately high levels of the hormone cortisol. This can be caused by taking glucocorticoid drugs, or diseases that result in excess cortisol, adrenocorticotropic hormone (ACTH), or CRH levels. What would you expect to happen to ACTH and cortisol levels in a patient with Cushing’s given dexamethasone?
cortisol levels would be relatively low and ACTH levels would be similar to normal, morning (relatively high)
Interpret these results from a dexamethasone suppression test:
No change to cortisol levels when patient administered low-dose dexamethasone, but lower levels of cortisol seen on high-dose dexamethasone.
Patient has Cushing’s disease
Interpret these results from a dexamethasone suppression test:
Patient administered low-dose and high dose dexamethasone, but cortisol levels remained unchanged.
Patient has a cortisol secreting adrenocortical tumor OR ectopic ACTH syndrome
Name (2) metabolic effects of glucocorticoids
- stimulate gluconeogenesis by inducing PEPCK, glucose-6-phosphatase, fructose-2, 6-bisphosphatase
- stimulates lipolysis AND lipogenesis resulting in MOON FACE & BUFFALO HUMP
True or False - In addition to the metabolic effects, glucocorticoids have immunosuppressive, anti-inflammatory effects, and stimulates gastric acid secretion?
True - inhibits transcription factors necessary for production of cells that generate the inflammatory response AND inhibits enzyme responsible for releasing arachidonic acid (precursor of inflammatory mediators)
Name 12 AE associated with long-term/high dose glucocorticoids?
- increase acid in GI
- edema
- osteoporosis
- gluconeogenesis
- growth inhibition
- CNS effects (euphoria, insomnia, depression)
- myopathy
- ocular effects
- moon face
- acne
- hirsutism (extra growth of hair esp in females)
- purpura (purple skin)
Cortisol (active-binds to MR and GR) is converted to Cortisone (inactive-does not bind to MR and GR) in the kidneys what enzyme isoform?
Type 2 isoform 11B-HSD2
11B-hydroxysteroid dehydrogenase-2
Cortisone (inactive-does not bind to MR and GR) is converted to Cortisol (active-binds to MR and GR) in the liver and fat by what enzyme isoform?
Type 1 isoform (11B-HSD1)
11B-hydroxysteroid dehydrogenase-1
Which 11B-HSD isoform protects the MR from the high circulating concentrations of cortisol?
Type 2 isoform 11B-HSD2
Lack of Type 2 isoform 11B-HSD2 can lead to what (2) conditions?
- HTN
- Hypokalemia (from overstimulation of MR)
If you’re lacking Type 2 isoform, you can’t convert the active cortisol to in the inactive cortisone resulting in over stimulation of MR
What is the most frequent problem associated with steroid withdrawal?
flare-up of the underlying disease for which steroids were prescribed to treat
What is the most SEVERE complication of rapid steroid cessation?
HPA shock (adrenal insufficiency)
What type of dosing regimen is employed when large doses of steroids are required for Tx for prolonged periods of time?
alternate-day administration to allow body recovery time in between doses
True or False - the longer one has been taking steroids, the slower the taper needs to be when coming off the steroids?
True
True or False - a single dose of glucocorticoid has virtually no harmful effects?
True - even a short course of therapy (up to 7 days) is unlikely to cause harm (excluding contraindications)