Biosynthesis of Steroid Hormones

Question 1

What steroid is this?

Answer 1

Cortisol

Question 2

What steroid is this?

Answer 2

progesterone

Question 3

What steroid is this?

Answer 3

aldosterone

Question 4

What steroid is this?

Answer 4

17b-estradiol

Question 5

What steroid is this?

Answer 5

testosterone

Question 6

What are the characteristics of endocrine signaling?

Answer 6

1. hormone only and travels fairly far through the blood to a target organ expressing receptors
2. low in conc. and high in affinity
3. minutes to hours

Question 7

what are the common features of steroid hormones?

Answer 7

1. synthesized from cholesterol
2. exist in low conc.
3. bound to serum carrier proteins
4. planar, rigid, and hydrophobic –> tight binding
5. shares similar mode of action

Question 8

what are the common mechanisms for steroid hormones?

Answer 8

1. regulate transcription of a specific set of genes
2. free hormones diffuse thru cell and bind to specific hormone receptor

Question 9

what steroid hormones are adrenocortical hormones?

Answer 9

cortisol and aldosterone

Question 10

what steroid hormones are sex and progestational hormones?

Answer 10

progesterone, 17b-estradiol, testosterone

Question 11

what are intracellular receptors?

Answer 11

1. binding to receptor
2. happens inside the cell going into nucleus
3. from nucleus leaves as mRNS
4. alters gene transcription

Question 11

what are the enzymes used in appearance of steroid hormone synthesis?

Answer 11

1. P450scc
2. 17a- hydroxylase
3. 17,20- lyase
4. 21- hydroxylase or aromatase depending on pathway
5. 17b hydroxysteroid dehydrogenase or 11b- hydroxylase depending on pathway

Question 12

what are cell surface receptors?

Answer 12

1. cells bind to receptor on cell surface
2. goes from low to high conc. of second messengers

Question 12

what are the major organs involved in steroid synthesis?

Answer 12

hypothalamus, adrenal gland, liver, gallbladder, pituitary gland, kidney

Question 13

what drugs are used to regulate steroid synthesis?

Answer 13

ketoconazole & aminoglutethimide

Question 14

what is ketoconazole?

Answer 14

1. non-selective steroidogenesis inhibitors
2. antifungal @ lower conc.
3. block synthesis of ergosterol
4. inhibits multiple enzymes (P450, 17a-hydroxylase, 11b- hydroxylase)
5. can treat hyperglucocorticoid states
6. toxic side effects potential

Question 15

what is aminoglutethimide?

Answer 15

1. non-selective steroidogenesis inhibitors
2. inhibit aromatase and P450
3. used to block steroid production in some hormone dependent tumors (breast and prostate)

Question 16

what two deficiencies can you have in steroid hormones?

Answer 16

17a-hydroxylase & 21-hydroxylase

Question 17

what does the 17a-hydroxylase deficiency do?

Answer 17

1. rare form of adrenal hyperplasia
2. mutations in CYP17A1 (17a-hydroxylase & 17,20-lyase)
3. overprod. of mineralcorticoids & deficiency of corticosteroids/ sex hormones

Question 18

what does the 21-hydroxylase deficiency do?

Answer 18

1. major form of adrenal hyperplasia
2. mutations in CYP 21a2 (21-hydroxylase)

Question 19

what are the symtpoms of 17a- hydroxylase deficiency?

Answer 19

1. hypoccortisolism –> enlargement of adrenal glands
2. ambiguous genitalia
3. hyperaldosteronism –> HTN

Question 20

what are the symptoms of 21- hydroxylase?

Answer 20

1. hypocotosolism
2. hypoaldosteronism –> hyponatremia
3. premature androgen exposure
   – ambiguous genitalia in female
   – hirsutism
   – early epiphyseal closure –> short stature

Question 21

what are the intermediates for steroid synthesis?

Answer 21

1. pregnenolone
2. DHEA
3. progesterone
4. androstenedione
5. estrone