Eicosanoids And Related Compounds

Question 1

Eicosanoids are produced from

Answer 1

Arachidonic acid

Question 2

What are the roles of Eicosanoids?

Answer 2

Inflammation
Fever
Regulation of blood pressure
Blood clotting
Immune system modulation
Control of reproductive processes and tissue growth
Sleep/wake cycle regulation

Question 3

Examples of Eicasoinds

Answer 3

Prostaglandins
Thromboxanes
Prostacylins
Leukotriens

Question 4

Which enzyme converts Arachidonic Acid to Eicosanoids?

Answer 4

Prostacyclins, Prostaglandisn, Thromboxanes by Cyclooxygenase (COX)
Leukotrienes by Lipoxygenase

Question 5

How is the structure of Arachidonic acid?

Answer 5

20 C poly-unsaturated fat acid
Has 4 double bonds

Question 6

How do we determine the name of Prostaglandins?

Answer 6

A letter code is based on ring formation ( hydroxyl, keto).
A subscript refers to the number of double bonds in the two side-chains.

Question 7

What are the three major class of Prostaglandins?

Answer 7

E— b-hydroxyketone
F— 1,3 diols
A— a,b unsaturated ketone

Question 8

How does Arachidonic acid release occur?

Answer 8

Directly from a membrane phospholipid, catalyzed by Phospholipase A2
From Diacyglycerol, catalyzed by diacylglycerol kinase.

Question 9

How is the Linear pathway occur?

Answer 9

From arachidonate to leukotriense by Lipoxyganase

Arachidonate— 5-Lipoxygenase— 5-HPETE— Leukotriene A4—Leukotrienes

Question 10

How does the Cyclic pathway occur?

Answer 10

arachidonate—prostaglandin H2 by PGH2 Synthase
Prostaglandin H2—prostacyclins by Prostacyclins synthase
—Thromboxanes by Thromboxanes Synthase

Question 11

How is the pathway of producing arachidonate from diacylglycerol?

Answer 11

Phosphatidyl Inositol— PIP2— Phospholipase C — Diacylglycerol + IP3— Diacylglycerol Lipase— AA

Question 12

PGH2 Synthase exhibits which 2 activities?

Answer 12

Cyclooxygenase (COX)
Peroxidase

Question 13

How is the Cytochrome P450 Epoxygenase Pathways?

Answer 13

Epoxyeicosatrienoic acids (EETs) and Hydroxyeicosatrienoic acids are formed from Arachidonate by enzymes of Cytochrome P450 family.

Question 14

What is PPARg?

Answer 14

Prostaglandin receptor
Nuclear receptor with transcription factor activity

Question 15

What are the subscripts of prostaglandin receptors?

Answer 15

EP1
EP2
EP3
….

Question 16

What are the receptors for E-class Prostaglandins?

Answer 16

EP

Question 17

What are the receptors for Thromboxanes?

Answer 17

TP

Question 18

What is the Leukotriene receptor?

Answer 18

G-protein coupled receptors

Question 19

5-Lipoxygenase requires whic protein?

Answer 19

FLAP— binds to AA, facilitating its interaction with the enzyme

Question 20

Why Corticosteroids are Anti-inflammatory?

Answer 20

Bc they prevent inducible Phospholipase A2 expression, reducing AA release.
Inhibit the PROSTAGLANDIN release
Ex: Asthma

Question 21

What are the effects of Non-Steroidal Anti-Inflammatory Drugs?

Answer 21

Inhibition of COXs
Inhibition of fever,pain,inflammation— blocking Prostaglandins
Inhibition of blood clotting— blocking Thromboxanes
Ex: Ibuprofen, aspirin

Question 22

Which essential role does Thromboxane have?

Answer 22

Stimulation of blood platelets aggregation
Blood clotting

Question 23

What are the two isoforms of PGH2 Synthase?

Answer 23

COX1
COX2

Question 24

COX1?

Answer 24

Constitutively expressed
Essential for Thromboxane formation and Prostaglandin
Maintaining the integrity of the GIS epi.
Vasoconstriction
Renal function

Question 25

COX2?

Answer 25

Inducible Prostaglandin and Prostacyclin Expression stimulated by growth factors, cytokines and endotoxins Expressed when needed Increase levels in inflammatory diseases Increased levels in cancer patients Vasodilation Inhibits platelet aggregation

Question 26

Features of COX2 inhibitors?

Answer 26

Anti-inflammatory Block pain Can cause blood clots

Question 27

COX3?

Answer 27

Inflammatory Mediation of pain and fever Inhibited by acetaminophen

Question 28

Functions of Prostaglandins?

Answer 28

Inflammatory response activation Production of pain,fever.. Blood clotting by TX GIS Kidney

Question 29

Anti-asthma medications?

Answer 29

Include inhibitions of 5-Lipoxygenase so that Leukotrienes can nor be produce and cannot cause vasoconstriction. Blocks the Leukotriene-receptor interaction

Question 30

Biological effects of Prostaglandins?

Answer 30

Contraction or Relaxation on; Respiratory tract GIS Urogenital tract Blood vessels

Question 31

Physiological function of PGD2?

Answer 31

Weak inhibitor of platelet aggregation

Question 32

Physiological effect of PGE1?

Answer 32

Bronchial vasodilations Inhibitor of lypolysis Inhibitor of platelet aggregation Contraction of GI smooth muscle

Question 33

Physiological effects of PGE2?

Answer 33

Renal and Bronchial vasodilation

Question 34

Physiological effects of PGF2?

Answer 34

Stimulation of uterine smooth muscle relaxation

Question 35

Physiological effects of PGI2

Answer 35

Potent inhibitor of platelet aggregation

Question 36

Physiological effects of TXA2

Answer 36

Potent inducer of platelet aggregation

Question 37

Which Eicosanoids have an effect on blood pressure?

Answer 37

TXA2 increases PGI2 decreases

Question 38

Vasodilation?

Answer 38

Prostaglandins and Prostacyclins

Question 39

Vasoconstriction?

Answer 39

Prostaglandins and Thromboxanes