What are the 5 classes of steroid hormones?
-Glucocorticoids -Mineralocorticoids -Androgens -Estrogens -Progestins
Synthesis and secretion of cortisol and aldosterone occur in what?
Adrenal cortex
Synthesis and secretion of estrogens and progestins occur in what?
Ovaries and ovarian corpus luteum
Synthesis and secretion of testosterone occurs in what?
Testes
What is the blood carrier protein used by cortisol?
Transcortin
What is the blood carrier protein used by the sex hormones?
Sex hormone-binding protein
Hydrophobic steroid hormones can be non-specifically carried by what?
Albumin
What molecule is used to transport cholesterol into the mitochondria?
StAR (Steroidogenic acute regulatory protein)
What is the regulatory step of cortisol synthesis?
Transport of cholesterol into mitochondria by StAR
In the initial reaction of steroid hormone synthesis, cholesterol gets converted to what?
Pregnenolone
What is the role of 3-B-hydroxysteroid dehydrogenase?
Oxidizes and isomerizes pregnenolone to progesterone
What is the role of Cholesterol Esterase?
Cleaves Cholesterol esters into Cholesterol. (this enzyme is activated by PKA)
The rate-limiting step of steroid hormone synthesis requires what two molecules?
-NADPH -O2
What is the rate limiting enzyme in steroid hormone synthesis?
Desmolase (aka: Cholesterol Side Chain Cleavage Enzyme CYP 11A1 P450 scc)
____________ reactions modify progesterone to other steroid hormones
Hydroxylation
Most enzyme (hydroxylases) in steroid biosynthesis are _____________ enzymes
Cytochrome P450-dependent
What region of the Adrenal gland releases Aldosterone?
Z. Glomerulosa
What region of the Adrenal Gland releases Cortisol?
Z. Fasciculata
What region of the Adrenal gland releases androgens (DHEA, Androstenedione)
Z. Reticularis
What does ACTH stand for?
Adrenocorticotropic hormone
ACTH, through actions of cAMP, stimulate synthesis of what steroid?
Cortisol
Angiotensin II/III, through actions of PIP2/IP3/Ca2+, stimulate synthesis of what steroid?
Aldosterone
Follicle Stimulating Hormone (FSH), through action of cAMP, stimulates synthesis of what steroid?
Estradiol
Luteinizing Hormone (LH), through action of cAMP, stimulates synthesis of what steroid?
Progesterone and Testosterone
In general, what are the actions of cortisol once released?
-Stimulate gluconeogenesis -Anti-inflammatory action -Protein breakdown in muscle.
How does cortisol counteract the action of insulin?
Cortisol leads in general to degradation of muscle protein
What are the 3 ways cortisol is involved in reducing inflammation?
- Inhibits Phospolipase A2 -Less arachidonic acid available for synthesis of eicosanoids (inflammatory mediators) -Inhibits induction of COX-2
What is the role of aldosterone?
-Raises blood pressure and fluid volume -Increases Na+ uptake
What are the two main androgens?
Dehydroepiandrosterone (DHEA) Androstenedione
What type of cells contain LH receptors, which increases cAMP and PKA resulting in testosterone synthesis?
Leydig Cells
