Lecture 09: Gonadal Hormones & Prostaglandins

Characteristics of steroid hormones

* HIGH molecular weight
* common 4 ring building block
* synthesized from cholesterol
* lipid soluble

Building block of cholesterol

Acetate (2 C)

How many carbons are in cholesterol

27

List the reasons cholesterol is considered essential

* Component of cell membranes
* Production of steroid hormones
* Part of bile manufacturing

Cellular organelle responsible for cholesterol production

Smooth ER

Cellular organelle responsible for steroid hormone production

Mitochondria

Name the cholesterol carrier protein and why it’s needed

Steroidogenic Acute Regulatory Protein (StAR protein) transports the hydrophobic cholesterol molecule through the aqueous cytoplasm and aqueous intermembrane space of the mitochondria so steroidogenesis can happen. Cholesterol transport into the mitochondria is the RDS of steroidogenesis.

What enzyme cleaves the side chain off of cholesterol, and how many carbons get cut off

P450 scc cleaves off 6 carbons

List the 5 classes of steroid hormones

* Progestagens
* Androgens
* Estrogens
* Glucocorticoids
* Mineralocorticoids

What initial hormone and hormone class is produced after cholesterol interacts with P450 scc

Pregnenolone, progestagens

What enzyme converts progestagens to androgens

17,20-lyase

What enzyme converts androgens to estrogens

Aromatase

How many carbons are in progestagens

21 C

How many carbons are in androgens

19 C

How many carbons are in estrogens

18 C

Characteristics of eicosanoid hormones

* 20 C
* synthesized from arachidonic acid

List the 3 classes of eicosanoid hormones

* prostaglandins
* thromboxanes
* leukotrienes

Arachidonic acid synthesis pathway

Ligand binds to receptor → activates phospholipase A2→ PLA2 grabs phospholipid from PM→ lipase grabs triglyceride→ PL + TG = arachidonic acid

Leukotriene synthesis pathway

Arachidonic acid goes through LOX (lipooxygenase)

Function of leukotrienes in the body

Immune system, inflammation, asthma

Thromboxane synthesis pathway

Arachidonic acid goes through COX (cyclooxygenase), forming PGH2, then some unspecified pathway

Function of thromboxanes in the body

Vasoconstriction, platelets, blood clotting

PGF2a synthesis pathway

Arachidonic acid → COX → PGH2 formed → PGE2 synthase → PGE2 formed → carbonyl reductase 1 → PGF2a

Function of PGE2 in the body

Decreases BP, smooth muscle contraction, inflammation

Function of PGF2a in the body

Destroys CL (luteolysis), smooth muscle contraction, increases BP