L18: Eicosanoids

Question 1

What are the 3 main categories of eicosanoids

Answer 1

Prostaglandins
Thromboxanes
Leukotrienes

Question 2

What are eicosanoids

Answer 2

Lipid derivatives that are locally synthesised and acting in the body

Question 3

What are the major function of eicosanoids

Answer 3

Inflammation

Question 4

Are eicosanoids stored in the body

Answer 4

No they are made as required

Question 5

What is eicosanoids made from

Answer 5

Arachidonic acid

Question 6

How is prostanoids synthesised from arachidonic acid

Answer 6

1) arachidonic acid is liberated from the membrane by phospholipase A2 enzyme
2) cox-1 or cox-2 act on the arachidonic acid to generate free intermediates of cyclo endoperoxides
3) if cox-2 acts then prostacyclin synthase acts on cyclic endoperoxides it gives prostacyclin
4) if cox-1 acts then thromboxane synthase acts on cyclic endoperoxides it gives TXA2

Question 7

What are prostanoids

Answer 7

Groups of eicosanoids of:
Prostaglandins
Thromboxanes

Question 8

When does cox-2 act on free arachadonic acid

Answer 8

During inflammation

Question 9

Which cell makes prostacyclin

Answer 9

Endothelium

Question 10

What makes. TXA2

Answer 10

Platelets

Question 11

How is leukotrienes synthesised by free arachidonic acid

Answer 11

1) arachidonic acid is liberated from membranes by phospholipase A2
2) lipoxygenase enzyme acts on the free arachidonic acid to give HPETE (intermediate compound)
3) HPETE gives leukotrienes of LTB4 and/or LTD4

Question 12

Which drugs inhibit cox-1 and cox-2 enzyme

Answer 12

NSAIDS

Question 13

Which drugs inhibits cox-2 only

Answer 13

Selective NSAIDS

Question 14

Which drugs reduced the expression of cox-2

Answer 14

Glucocorticoid

Question 15

What is the other role of glucocorticoid on the production of prostanoids and leukotrienes

Answer 15

Glucocorticoid increase the expression of annexin-1 which inhibit phospolipase A2
There is less arachidonic acid liberated therefore less prostanoids and leukotrienes made

Question 16

What is the role of prostaglandins

Answer 16

Inflammatory response
Vasodilation to allow movement of prostaglandins
Raise temperature
Increase peripheral sensory nerves for pain
Muscle contraction
Gastric mucous secretion
Inhibition of platelets aggregation

Question 17

Name a prostaglandin

Answer 17

Prostacyclin (PGI2)

Question 18

What is the role of thromboxanes

Answer 18

Vasoconstriction
Bronchoconstriction
Platelet aggregation

Question 19

Name an example of thromboxanes

Answer 19

TXA2

Question 20

What do eicosanoids bind to once produced to bring about their effects

Answer 20

G-protein coupled receptors

Question 21

Which drugs inhibits 5-lipoxgenase to reduce leukotrienes

Answer 21

Zileuton

Question 22

In which clinical condition is zileuton used in

Answer 22

Asthma

Question 23

What other drugs act to alter leukotriene production

Answer 23

Glucocorticoid by inducing annexin-1 which inhibits phosholipaseA2 to reduce overall eicosanoids production

Question 24

What is the role of leukotriene

Answer 24

Attract neutrophil and macrophages to site of inflammation
Simulate proliferation of immune cells
Involved in rhematoid arthritis, ulcerative colitis
Bronchoconstriction
Mucus secretion
Vasodilation and vasoconstriction

Question 25

What is the name of the receptor that prostacyclin binds to

Answer 25

IP

Question 26

What happens when prostacyclin binds to it’s receptor

Answer 26

Activates CAMP and protein kinase A

Question 27

What is the name of the receptor that TXA2 binds to

Answer 27

TP

Question 28

What happens when TXA2 binds to its receptor

Answer 28

Activates phospholipase C and protein kinase C

Question 29

What is the pathway for leukotrienes when it binds to leukotrienes receptor

Answer 29

Phospholipase c | Protein kinase c

Question 30

Name an leukotrienes receptor antagonist

Answer 30

Montelukast

Question 31

When is montelukast used

Answer 31

In asthma

Question 32

Name an IP receptor agonist

Answer 32

Epoprostenol

Question 33

When is epoprostenol used

Answer 33

In pulmonary hypertension

Question 34

Name an EP receptor agonist

Answer 34

Misoprostol

Question 35

When is misoprostol used

Answer 35

In gastric ulcer to reduce hydrochloric acid

Question 36

Does cox-1 result in vasodilation or vasoconstriction

Answer 36

Vasoconstriction

Question 37

Does cox-2 result in vasodilation or vasoconstriction

Answer 37

Vasodilation

Question 38

What is thrombosis

Answer 38

Blood clotting

Question 39

Why is the balance of cox-1 and cox-2 important

Answer 39

To stop thrombosis from occuring

Question 40

What are the 2 ways preventing thrombosis

Answer 40

Fish oil | Aspirin

Question 41

Does leukotrienes result in bronchoconstriction or bronchodilation

Answer 41

Bronchoconstriction

Question 42

Does prostanoids give bronchoconstriction or bronchodilation

Answer 42

Both

Question 43

Name 3 drugs used to treat allergic asthma

Answer 43

Glucocorticoids Zileuton Montelukast