Biosynthesis of Steroid Hormones Flashcards
What steroid is this?
Cortisol
What steroid is this?
progesterone
What steroid is this?
aldosterone
What steroid is this?
17b-estradiol
What steroid is this?
testosterone
What are the characteristics of endocrine signaling?
- hormone only and travels fairly far through the blood to a target organ expressing receptors
- low in conc. and high in affinity
- minutes to hours
what are the common features of steroid hormones?
- synthesized from cholesterol
- exist in low conc.
- bound to serum carrier proteins
- planar, rigid, and hydrophobic –> tight binding
- shares similar mode of action
what are the common mechanisms for steroid hormones?
- regulate transcription of a specific set of genes
- free hormones diffuse thru cell and bind to specific hormone receptor
what steroid hormones are adrenocortical hormones?
cortisol and aldosterone
what steroid hormones are sex and progestational hormones?
progesterone, 17b-estradiol, testosterone
what are intracellular receptors?
- binding to receptor
- happens inside the cell going into nucleus
- from nucleus leaves as mRNS
- alters gene transcription
what are the enzymes used in appearance of steroid hormone synthesis?
- P450scc
- 17a- hydroxylase
- 17,20- lyase
- 21- hydroxylase or aromatase depending on pathway
- 17b hydroxysteroid dehydrogenase or 11b- hydroxylase depending on pathway
what are cell surface receptors?
- cells bind to receptor on cell surface
- goes from low to high conc. of second messengers
what are the major organs involved in steroid synthesis?
hypothalamus, adrenal gland, liver, gallbladder, pituitary gland, kidney
what drugs are used to regulate steroid synthesis?
ketoconazole & aminoglutethimide
what is ketoconazole?
- non-selective steroidogenesis inhibitors
- antifungal @ lower conc.
- block synthesis of ergosterol
- inhibits multiple enzymes (P450, 17a-hydroxylase, 11b- hydroxylase)
- can treat hyperglucocorticoid states
- toxic side effects potential
what is aminoglutethimide?
- non-selective steroidogenesis inhibitors
- inhibit aromatase and P450
- used to block steroid production in some hormone dependent tumors (breast and prostate)
what two deficiencies can you have in steroid hormones?
17a-hydroxylase & 21-hydroxylase
what does the 17a-hydroxylase deficiency do?
- rare form of adrenal hyperplasia
- mutations in CYP17A1 (17a-hydroxylase & 17,20-lyase)
- overprod. of mineralcorticoids & deficiency of corticosteroids/ sex hormones
what does the 21-hydroxylase deficiency do?
- major form of adrenal hyperplasia
- mutations in CYP 21a2 (21-hydroxylase)
what are the symtpoms of 17a- hydroxylase deficiency?
- hypoccortisolism –> enlargement of adrenal glands
- ambiguous genitalia
- hyperaldosteronism –> HTN
what are the symptoms of 21- hydroxylase?
- hypocotosolism
- hypoaldosteronism –> hyponatremia
- premature androgen exposure
– ambiguous genitalia in female
– hirsutism
– early epiphyseal closure –> short stature
what are the intermediates for steroid synthesis?
- pregnenolone
- DHEA
- progesterone
- androstenedione
- estrone
