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Irm > L18: Eicosanoids > Flashcards

L18: Eicosanoids Flashcards

1
Q

What are the 3 main categories of eicosanoids

A

Prostaglandins
Thromboxanes
Leukotrienes

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2
Q

What are eicosanoids

A

Lipid derivatives that are locally synthesised and acting in the body

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3
Q

What are the major function of eicosanoids

A

Inflammation

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4
Q

Are eicosanoids stored in the body

A

No they are made as required

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5
Q

What is eicosanoids made from

A

Arachidonic acid

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6
Q

How is prostanoids synthesised from arachidonic acid

A

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

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7
Q

What are prostanoids

A

Groups of eicosanoids of:
Prostaglandins
Thromboxanes

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8
Q

When does cox-2 act on free arachadonic acid

A

During inflammation

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9
Q

Which cell makes prostacyclin

A

Endothelium

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10
Q

What makes. TXA2

A

Platelets

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11
Q

How is leukotrienes synthesised by free arachidonic acid

A

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

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12
Q

Which drugs inhibit cox-1 and cox-2 enzyme

A

NSAIDS

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13
Q

Which drugs inhibits cox-2 only

A

Selective NSAIDS

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14
Q

Which drugs reduced the expression of cox-2

A

Glucocorticoid

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15
Q

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

A

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

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16
Q

What is the role of prostaglandins

A

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

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17
Q

Name a prostaglandin

A

Prostacyclin (PGI2)

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18
Q

What is the role of thromboxanes

A

Vasoconstriction
Bronchoconstriction
Platelet aggregation

19
Q

Name an example of thromboxanes

A

TXA2

20
Q

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

A

G-protein coupled receptors

21
Q

Which drugs inhibits 5-lipoxgenase to reduce leukotrienes

A

Zileuton

22
Q

In which clinical condition is zileuton used in

A

Asthma

23
Q

What other drugs act to alter leukotriene production

A

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

24
Q

What is the role of leukotriene

A

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

25
Q

What is the name of the receptor that prostacyclin binds to

A

IP

26
Q

What happens when prostacyclin binds to it’s receptor

A

Activates CAMP and protein kinase A

27
Q

What is the name of the receptor that TXA2 binds to

A

TP

28
Q

What happens when TXA2 binds to its receptor

A

Activates phospholipase C and protein kinase C

29
Q

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

A

Phospholipase c

Protein kinase c

30
Q

Name an leukotrienes receptor antagonist

A

Montelukast

31
Q

When is montelukast used

A

In asthma

32
Q

Name an IP receptor agonist

A

Epoprostenol

33
Q

When is epoprostenol used

A

In pulmonary hypertension

34
Q

Name an EP receptor agonist

A

Misoprostol

35
Q

When is misoprostol used

A

In gastric ulcer to reduce hydrochloric acid

36
Q

Does cox-1 result in vasodilation or vasoconstriction

A

Vasoconstriction

37
Q

Does cox-2 result in vasodilation or vasoconstriction

A

Vasodilation

38
Q

What is thrombosis

A

Blood clotting

39
Q

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

A

To stop thrombosis from occuring

40
Q

What are the 2 ways preventing thrombosis

A

Fish oil

Aspirin

41
Q

Does leukotrienes result in bronchoconstriction or bronchodilation

A

Bronchoconstriction

42
Q

Does prostanoids give bronchoconstriction or bronchodilation

A

Both

43
Q

Name 3 drugs used to treat allergic asthma

A

Glucocorticoids
Zileuton
Montelukast

Irm (21 decks)

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