- Progestins-progesterone, pregnenolone
- Glucocorticoids- cortisol, corticosterone
- Mineralorcorticoids- aldosterone, 11-deoxycorticosterone
NOTE: C21 steroids with OH at C17 are called 17- hydroxysteroids
Androgens-testosterone, androstenedione, DHEA, DHT
Estrogens- Estradiol, estrone, estriol
Conversion of cholesterol to pregnenolone is by ____________ enzyme.
Side-chain cleavage enzyme (CYP 11A1)
NOTE: This occurs in the inner mitochondrial membrane and this step is rate-limiting for steroidogenesis.
Most steroidogenic enzymes belong to the ________ family and are thus reffered to as CYPs.
P-450 monooxidase gene family
Aldosterone is inhibited by ________.
NOTE: Aldosterone is stimulated by angiotensin II, high potassium, and acutely elvated ACTH.
___________ cataylzes the last 3 reactions fro 11-deoxycorticosterone (DOC) to aldosterone.
Aldosterone synthase (CYP11 B2)
*This enzyme is unique to the zona glomerulosa
What role does ACTH play in the transport of cholesterol?
ACTH increases the number of adrenocotical cell receptors for LDL
NOTE: ACTH also increases de novo synthesis of cholesterol from acteyl CoA (primarily catalyzed by cholesterol esterase hydroxylase a.k.a hormone sensitive lipase)
Which hormones is necessary for the formation of cortisol?
CYP 17 17 a-hyroxylase
Cortisol is reversibly inactivated to cortisone by _______.
11b-hydroxysteroid dehydrogenase Type 2
NOTE: This serves to protect mineralocorticoid receptors in aldosterone responsive cells
__________ converts cortison back to cortisol in tissues expressing the glucocorticoid receptor.
_________________ inhibits CYP11B1.
Corticosteroids and their relative glucocorticoid and mineralocorticoid activities compared to cortisol
A constellation of clinical abnormalities caused by chronic high levels of cortisol or related corticosteroids
- Central obesity
- Metabolic syndrome
Excess pituatary production of ACTH, generally secondary to a pituitary adenoma
What enzyme is unique to the zona reticularis?
17,20 lyase (CYP 17)
NOTE: The major androgen secreted by the zona reticularis is DHEA
________ inhibits cholesterol side-chain cleavage enzyme, 17a-hydroxylase and 17,20 lyase activity.
____________ deficiency accounts for 90% of all congenital adrenal hyperplasia cases.
21 B- Hydroxylase
NOTE: If there is a 21 B- hyrdroxylase deficiency 17-OH Progesterone will be elevated, which will lead to an elevation in androgen secretion.
Treatment for congenital adrenal hyperplasia
- Long-term glucocorticoid or aldosterone replacement (or both)
What is the major difference between congenital adrenal hyperplasia as result of 11B-hydroxylase deficiency as opposed to 21- B- hydroxylase deficiency?
Hypertension along with hypokalemia
NOTE: It should be treated with glucocorticoids
Testosterone synthesis from cholesterol can take four pathways, the _____ pathway is preferred.
Human testes secrete a small portion of DHT. Most DHT is derived from peripheral conversion of testosterone by __________.
5a-reductase type 2
Human testes make small, but significant amounts of 17b-estradiol. Most E2 comes from peripheral _________ of androstenedione and testosteron.e
17B hydorxysteroid dehyrogenase (TYPE 3) mutation is caused by mutations in the _______ gene.
NOTE: It is clinically indistinguishable from androgen insensitivity syndrome in prepubertal patients
5a- reductase deficiency
- Genetic males are born with ambiguous genitalia
- Clinical abnormalities range from infertility with normal male anatomy to underdeveloped male anatomy with hypospadias to predominant female genitalia
CYP19 is also known as __________
Two cell model of Steroidogenesis in the dominant ovarian follicle
The liver convers estradiol and estrone to _______.
NOTE: Hepatic enzymes add glucuronide or sulfate moieties for excretion in the bile
The major metabolite of progesterone is ___________, which is conjugated with glucuronide and excreted in urine.
_______________ convert cortisol to cortisone.
NOTE: Syncytiotrophoblasts lact CYP17