Lecture 31: Steroid Biosynthesis Flashcards
What enzyme converts cholesterol into pregnenolone?
Desmolase
-rate activating step
What regulates desmolase activity?
ACTH
What role does progesterone play in pregnancy?
Supports pregnancy
- regulates voltage gated calcium channels on spermatozoa
- prepares uterus for pregnancy
- smooth muscle relaxation
- decreases maternal immune response
What role does glucocorticoids play in newborn infants?
Stimulates surfactant production to allow babies to breathe
-w/o it can cause IRDS
What is pregnenolone a precuros to?
Progesterone Aldosterone Cortisol Testosterone Estradiol
What is adrenal hyperplasia?
Disease that limits hormone production in the adrenal glands
-deficiencies in adrenal enzymes
How can women present with adrenal hyperplasia?
- Hirsutism
- General oligomenorrhea
- Infertility
How is adrenal hyperplasia diagnoses?
- HLA haplotype
- excess cortisol precursors in amniotic fluid
What happens if there is a 21-hydroxylase deficiency?
Salt-wasting (no aldosterone)
- Build up of progesterone and 17-α hydroxy progesterone
- excess esterone and testosterone produced
What happens if there is a 11-β-hydroxylase deficiency?
Salt-loving
- accumulation of corticosterone and 11-deoxycortisol
- acts like aldosterone so increased sodium absorption that can lead to increased BP
What is primary aldosteronism?
Conn’s Syndrome
- promotes retention of sodium and water
- excretes hydrogen and potassium
- can lead to high BP
What transports a majority of steroid hormones?
CBG (corticosteroid-binding globulin)
How does ACTH act on the zona fasciculata part of the adrenal cortex?
Secretion of glucocorticoid steroid hormones
-cortisol
Why is the the CYP17A1 gene important?
17,20 Lyase
-how sex hormones are produced
How does cortisol suppress immune system?
Induce production of I-κBα inhibitory protein
-prevents secretion of NF-κB, which stimulates cytokine production
