Glossary of Biochemistry - Steroid Hormones

Start Studying! Add Cards ↓

Cholesterol - Precursor of all classes of steroid hormones. What are the classes?
Glucocorticoids: Cortisol
Mineralcorticoids: Aldosterone
Sex Hormones: Androgens, Estrogens, Progestins
Note: Glucocorticoids and Mineralcorticoids are called corticosteroids
Location of Secretion and Synthesis of steroid hormones
1.) Adrenal Cortex: Cortisol, Aldosterone, and Androgens
2.) Ovaries and Placenta: Estrogens and Progestins
3.) Testes: Testosterone
Carriers of steroid hormones - both specific and nonspecific carriers
1.) Albumin (non-specific carrier)
2.) Corticosteroid-binding Globulin (Transcortin): Transports cortisol
3.) Sex Hormone-binding Protein: Transports Sex Hormones
General synthesis of steroid hormones requires?
Shortening of the hydrocarbon chain and hydroxylation of the steroid nucleus
Cholesterol is converted to ______ by enzyme _______?
What does it require?
Pregnenolone (Parent compound of all steroid hormones) by a cholesterol side chain cleavage enzyme complex (desmolase [RATE LIMITING!!!] - a cytochrome P450 mixed function oxidase of the INNER mitochondrial membrane)
Requires NADPH and Molecular Oxygen
Source of cholesterol substrates for steroid hormone synthesis
1.) Newly synthesized
2.) Taken up from lipoproteins
3.) Released from cholesteryl esters stored in the cytosol of steroidogenic tissues
Note: steroid hormone synthesis consumes little cholesterol compared to bile acid synthesis
Hydroxylation reaction of pregnenolone occurs where?
ER and Mitochondria
This is following the oxidation step of pregnenolone to progesterone.
What are the different types of congenital adrenal hyperplasias (CAH)
1.) 3-β-Hydroxysteroid Dehydrogenase Deficiency
2.) 17-alpha-hydroxylase deficiency
3.) 11-β-hydroxylase deficiency
4.) 21-alpha-hydroxylase deficiency
5.) 5-alpha-reductase deficiency
Describe 3-β-Hydroxysteroid Dehydrogenase Deficiency
1.) No glucocorticoids, mineralocorticoids, androgens or estrogens
2.) Marked salt excretion
3.) All patients have female genitalia
4.) Total lost of all 5 steroid classes
5.) Probably terminal unless given perhaps hormone therapy
6.) All will have female characteristics because of lack of testosterone
Describe 17-alpha-hydroxylase deficiency
1.) No sex hormones or cortisol are produced
2.) Increased mineralocorticoids
Sodium and fluid retention, hypertension
3.) All patients have female genetalia
Describe 11-β-hydroxylase deficiency
1.) Decrease in cortisol, aldosterone and corticosterone
2.) Increased deoxycorticosterone, fluid retention, low renin hypertension
3.) Masculinization
4.) Making lots of testosterone
5.) 11-deoxycorticosterone has a very strong mineralcorticoid effect. Therefore, paradoxically build up aldosterone like activity. Causes sodium retention. Renin levels drop
Causes hypertension because of Sodium retention.
Describe 21-alpha-hydroxylase deficiency
1.) Most common
2.) Most common CAH, > 90% of all cases
3.) Partial (non-classic) and complete (classic) deficiencies known
4.) Production of cortisol and aldosterone blocked
5.) Lose retention of sodium and retain potassium
6.) Leads to heart arrhythmias
7.) Cortisol is necessary for vascular tone leading to hypotension
8.) Precursors shunted to androgen pathway
9.) Females are born with ambiguous genitalia, males display early virility
10.) Rapid growth, prematur bone fustion short adult stature
11.) Abnormal body hair (hersitism)
5 Classes of Steroid hormones
Corticosteroids -
1.) Glucocorticoids (Cortisol, adrenals)
Causes upregulation of glucose
2.) Mineralcorticoids (Adolsterone, adrenals)
Sodium potassium ratio

Sex Hormones -
3.) Androgens (testosterone, testes; androstenedione, andrenals)
4.) Estrogens (estrodiol, ovaries)
5.) Progestins (progesterone, corpus luteum
Desmolase Complex
1.) Member of the p450 family of proteins
In general p450 involved with steroids, processing of bile, and detoxification
2.) Puts hydroxy groups on to make more soluble
3.) Mitochondrial
4.) At least two separate enzyme complexes
5.) Removal of 6C from cholesterol
6.) Product is pregnenolone (C27-->C21)
7.) Requires NADPH and molecular O2 required
NADPH From HMP Shunt
8.) Regulated by cAMP levels (ACTH) Increases synthesis of desmolase. Increases synthesis in cholesterol esterase
9.) Removes the esterified fatty acid on the cholesteryl ester
Therefore, increases free cholesterol for steroid synthesis
**** process not enough to increase substantially cholesterol homeostasis.
10.) In adrenal cortex where ACTH is made can be turned off is a growth hormone that if not turned off can cause hyperplasia (adrenohyperplasia)

Add Cards

You must Login or Register to add cards