Eicosanoids

Question 1

What are eicosanoids and how do the act?

Answer 1

20 carbon fatty acids:
Prostaglandins (PG)
Thromboxanes (TX)
Leukotrienes (LT)
Lipoxins (LX)
Unstable so broken down quickly
Act like hormones

Question 2

How do eicosanoids act in the stomach?

Answer 2

Reduce acid secretion and increase mucus and bicarbonate secretion

Question 3

How do eicosanoids act in the kidney?

Answer 3

regulates blood flow and renin release

Question 4

How do eicosanoids act in the lungs?

Answer 4

bronchoconstriction

Question 5

How do eicosanoids act in the uterus?

Answer 5

Smooth muscle contration

Question 6

How do eicosanoids act in the eye?

Answer 6

regulates intraocular pressure

Question 7

How do eicosanoids act in platelets?

Answer 7

regulates aggregation

Question 8

How do eicosanoids act in pro-inflammation?

Answer 8

Vasodilation
Sensitise pain sensory neurones
Regulate temperature set-point

Question 9

How do eicosanoids act in anti-inflammation?

Answer 9

Decrease lysosomal enzyme, histamine and ROS release

Question 10

Where do eicosanoids come from?

Answer 10

Cell membrane components:
Phospholipase A2 releases arachidonate
Arachidonate transferase converts AD to Arachidonic acid
AA converted into 4 different groups by 4 different enzymes

Question 11

What are the enzymes that convert AA and what do they convert AA into?

Answer 11

12-lipooxygenase - 12-HETE (chemotaxin)
15-lipoxygenase - lipoxins
5-lipoxygenase - Leukotriene A4
COX - Cyclic endoperoxides (PGs + TXs)

Question 12

What are leukotrienes produced by?

Answer 12

Eosinophils, mast cells, basophils, macrophages

Question 13

What effect do LTs have on neutrophils?

Answer 13

Increase adhesion molecules, superoxide anions and release of granule enzymes

Question 14

What are the 5 derivatives of the Cyclic endoperoxides and their receptors?

Answer 14

PGF2a - FP receptor
PGI2 - IP receptor
PGD2 - DP receptor
PGE2 - EP receptor
TXA2 - TP receptor

Question 15

What does FP receptor binding cause?

Answer 15

Uterine contraction

Question 16

What does IP receptor binding cause?

Answer 16

Vasodilation
Inhibits platelet aggregation
Release of renin

Question 17

What does DP receptor binding cause?

Answer 17

Vasodilation
Inhibits platelet aggregation
Relaxes gut and uterine muscle

Question 18

What does TP receptor binding cause?

Answer 18

Vasoconstriction

Platelet aggregation

Question 19

What does EP1 receptor binding cause?

Answer 19

Bronchoconstriction

GI contration

Question 20

What does EP2 receptor binding cause?

Answer 20

Vasodilation
Bronchodilation
GI relaxation

Question 21

What does EP3 receptor binding cause?

Answer 21

GI contraction
Gastric acid secretion inhibition
Gastric mucus secretion
Contraction of pregnant uterus

Question 22

What does EP4 receptor binding cause?

Answer 22

Vasodilation

Question 23

What do NSAIDs do?

Answer 23

Inhibit COX - COX2 for inflammatory responses

Question 24

What are the desired effects of NSAIDs?

Answer 24

Vasodilation
Increase histamine + Bradykinin effects
Sensitise pain fibres
Regulate temperature set point

Question 25

What are NSAID ADRs?

Answer 25

Nephrotoxicity
Decrease in gastric mucus
Increase in gastric acid
Skin rashes
Vasodilation + Platelet aggregation

Question 26

What does aspirin do to COX in platelets?

Answer 26

Binds irreversibly with COX causing:
TX increase
Vasoconstriction
Platelet aggregation

Question 27

What does aspirin do to COX in Endothelial cells?

Answer 27

Binds irreversibly with COX causing:
PGI2 increase
Vasodilation
Disaggergation