Eicosanoids

Question 1

Types of eicosanoids

Answer 1

prostanoids
leukotrienes
lipoxins

Question 2

Types of Prostanoids

Answer 2

Prostacyclin - prostaglandin I2
Prostaglandin
Tromboxanes

Question 3

Leukotrienes

Answer 3

produced in WBCs

role in inflammation

Question 4

Types of Leukotrienes

Answer 4

Leukotriene A4:
-gatekeeper
-divided into B4 or C4
-inhibited by Zileuton
Leukotriene B4:
-produced by leukocytes
-chemoattractant
-allows WBC to leave blood vessels
Leukotriene C4,D4,E4:
-inflammation
-bronchoconstriction, vasoconstriction, smooth muscle constriction

Question 5

Prostacyclin

Answer 5

a prostanoid

role: vasodilator, bronchodilator. prevents platelet activation

Question 6

Prostaglandins

Answer 6

a prostanoid

role: induce birth, maintain patent PDA, treatment of peptic ulcers, vasodilator, erectile dysfunction, glaucoma

Question 7

Types of prostaglandins

Answer 7

Prostaglandin H2:
-gatekeeper
Prostaglandin D2:
-made by mast cells
-promotes immune cell recruitment
-bronchoconstriction, vasodilation
Prostaglandin E1:
-used in: PDA, erectile dysfunction, limb ischemia
-produced from dihomo-gamma-linolenic acid
Prostaglandin E2:
-vasodilator, bronchoconstrictor
-increase body temperature
-mucous formation, HCO3- secretion, mucosal blood flow, epithelial regeneration
Prostaglandin F2a

Question 8

Tromboxanes

Answer 8

a prostanoid
Thromboxane A2
-produced by activated platelets
-short half life
-role: activates other platelets, platelet aggregation. vasoconstriction
Thromboxane B2:
-inactive form

Question 9

Aspirin

Answer 9

inhibits cyclooxygenases

irreversible acetylatin of a SER

Question 10

Corticosteroids

Answer 10

inhibits phospholipase A2

Question 11

COX 1

Answer 11

in cytosol
narrow substrate binding site
PG products secreted
expressed continuously

Question 12

COX 2

Answer 12

in nuclear membrane
wide binding site
PG products may have nuclear targets
induced in inflammation and physiological imbalance

Question 13

Lipoxins

Answer 13

anti-inflammatory
receptors:
-agonist on their specific G protein receptor ALX
-antagonist on CysLT receptors
-bind to AhR nuclear receptor - SOCS 2
inhibits:
-neu activation, adhesion, Leu extravasation, synthesis of proinflammatory mediators, ROS production
promote:
-synthesis of anti-inflammatory mediators
-phagocytosis of apoptotic Neu-S

Question 14

Phospholipids/DAG -> Arachidonic acid

Answer 14

enzyme: Phospholipase A2

inhibited by corticosteroids

Question 15

Arachidonic acid -> Prostaglandin H2

Answer 15

enzyme: COX1, COX2, peroxidase
- PROSTAGLANDIN D2 SYNTHASE - prostaglandin D2
- PROSTAGLANDIN E SYNTHASE - PG E2 - PG F2
- PROSTACYCLIN SYNTHASE - PG I2
- THROMBOXANE SYNTHASE - thromboxane A2-thromboxane B2

Question 16

Arachidonic acid -> Arachidonic acid 5 hydroperoxide

Answer 16

enzyme: lipooxygenase

Question 17

Arachidonic acid 5 hydroperoxide -> Leukotriene A4

Answer 17

+ O2

Question 18

Leukotriene A4 -> Leukotriene B4

Answer 18

enzyme: leukotriene A4 hydrolase

+H2O

Question 19

Leukotriene A4 -> Leukotriene C4 -> D4 -> E4

Answer 19

enzyme: extracellular gamma glutamyl transpeptidase
+H2O
-Glu