Steroid Hormones

Question 1

Cholesterol esterase

Answer 1

activated by PKA to do CE–>cholesterol

Question 2

StAR

Answer 2

Steroidogenic acute regulatory protein

transports cholesterol to mitochondria to be converted to pregnenolone

Important regulatory step

Question 3

Desmolase Complex

Answer 3

shortens hydrocarbon chain, hydroxylation of the steroid nucleus: cholesterol side chain cleavage enzyme

Rate limiting step of steroid synthesis

Cyto P450 dependent monooxygenase
also requires NADPH and O2

Located in Mitochondria
aka: CYP 11A1, P450 scc

Question 4

3-ß-hydroxysteroid dehydrogenase

Answer 4

oxidizs and isomerizes pregnenolone
pregnenolone-->progesterone
17-hydroxypergnenolone-->17-hydroxyprogesterone
DHEA-->Androstenedione
Effects:

Question 5

Z. Glomerulosa

Answer 5

produces aldosterone

Question 6

Z. fasciculata

Answer 6

produces cortisol

Question 7

Z. Reticularis

Answer 7

produces DHEA and aldostedione. Testes finish up testosterone synthesis in males and ovaries convert to estrogens in females

Question 8

CYP 21A2

Answer 8

Progesterone–>deoxycorticosterone
17-hydroxyprogesterone–>11-deoxycortisol
21-hydroxylase
Downstream:alosterone, cortisol

Question 9

CYP11B

Answer 9

at position 11B
deoxycorticosterone-->corticosterone
11-deoxycortisol-->cortisol
mitochondria
11ß-hydroxylase
Downstream: aldosterone, cortisol

Question 10

CYP11B2

Answer 10

at postition 18
Aldosterone synthase, P450c11as
corticosterone–>Aldosterone

Question 11

CYP19

Answer 11

Androxstenedione–>estrone
Testosterone–>Estradiol
(only effects estradiol synthesis)
A, aromatase

Question 12

CYP17A1

Answer 12

17alpha-hydroxylase (P450c17)
@ 17alpha
pregnenolone-->17hydroxypregnenolone
progesterone-->17-hydroxyprogesterone
effects cortisol, sex hormones

Question 13

17,20

Answer 13

17-hydroxyprogesterone-->Androstenedione
17-hydroxypergnenolone-->DHEA
11-Deoxycortisol-->Anrdrostenedione
17, 20 lyase
effects sex hormones

Question 14

Regulation of cortisol

Answer 14

ACTH–>cortisol–|ACTH

Question 15

Cortisol

Answer 15

regulated by ACTH from pituitary

dominant glucocorticoid

synthesized from porgesterone in zona fasciculata

stress adaptation

needed for gluconeogenesis esp during prolonged starvation

degrades muscle (counteracts insulin)

affects immune system:
inhibits PLA2–> down arachidonic acid –> down eicosanoids (prostaglandins, thromboxanes and leukotrienes; Inhibits induction of cox-2

transported bound 75% transcortin, 15% albumin

Inflammation–>binding to transortin reduced–>[cortisol] up–>therefore: cortisol activity up

Question 16

Aldosterone

Answer 16

Principal mineral corticoid
raises blood pressure, fluid volume, increase Na+ uptake

stimulated by angiotensin II/III

Question 17

Estrogens

Answer 17

Stimulated by FSH and LH (pituitary)

estrogens: control menstrual cycle, development of 2º sex characteristics

Progesterone: secretory phase of uterus and mammary glands, implantation and maturation of fertilized ovum

Question 18

Androgens

Answer 18

dehydroepiandrosterone and androstenedione, testosterone

Z. retiularis and fasiculata
weak androgens converted to estradiol in fat cells and testosterone in testes

Question 19

Testosterone

Answer 19

LH–>up [cAMP]–>up PKA activity (leydig cells)

Sertoli cells–>dihydrotestosterone (DHT)

stimulates spermatogenesis, 2º sex characteristics, anabolism, masculinization of fetus

Question 20

steroid receptior

Answer 20

Located in cytosol or nucleus, hormone binding leads to (homo/hetero)dimerization, binds HRE, acts as enhanser or repressor of gene transcription

Question 21

3-ß hydrosteroid dehydrogenase deficiency

Answer 21

No glucocorticoids mineral corticoids, active androgens or estrogens

increased salt in urine

female like genetalia

Question 22

17-α-hydroxylase deficiency

Answer 22

no sex hormones or cortisol

increased mineralcorticoids–>up Na+, up fluids, up bp

female-like genetalia

Question 23

21-α-hydroxylase deficiency

Answer 23

most common form of CAH (partial and complete)
mineralocorticoids and glucocorticoids absent or deficient
over production of androgens leads to masculinization of external genitalia in females, early virilization in males

Question 24

11-β-hydroxylase deficiency

Answer 24

decrease cortisol, corticosterone, aldosterone
increased deoxycorticosterone–>fluid retention–>suppresses renin/angiotensin system (low renin hypertension)
masculinization and virilization

Question 25

Cushing’s syndrome

Answer 25

hypercortisolism/hyperfunction of adrenal cortex (usually due to tumor):
[cortisol] up, [ACTH] down
Protein loss and characteristic fat distribution (face, neck truncus)
hirsutism (early pubic hair)

Question 26

Addison’s disease

Answer 26

1º adrenal cortical insufficency (usually autoimmune)

aldosterone and cortisol low; ACTH high

FTT, muscle weakeness, fatigue, weight loss, hyperpigmentation, salt craving, hyponatremia, hyperkalemia, hypovolemia, hypotension, abdominal pain, vomiting, constipation