Eicosanoids

Question 1

what are the 3 types of eicosanoids?

Answer 1

prostaglandins
thromboxanes
leukotrienes

Question 2

which eicosanoids are associated with inflammation?

Answer 2

prostaglandins

thromboxanes

Question 3

which eicosanoid is associated with allergic reaction/hypersensitivity?

Answer 3

leukotrienes

Question 4

how do eicosanoids act and exert effects?

Answer 4

autocrine or paracrine = locally
through receptor-mediated G-protein linked signaling leading to an increase in either c-AMP or increase in intracellular Ca2+

Question 5

all cells except what synthesize eicosanoids?

Answer 5

erythrocytes!

Question 6

where does arachidonic acid reside in the cell?

Answer 6

C-2 posotion of membrane phospholipids

Question 7

how is arachidonic acid released from phospholipids?

Answer 7

phopholipase A2

Question 8

what structures do eicosanoids affect in inflammatory responses?

Answer 8

joints, skin, eyes

Question 9

what do eicosanoids play an important role in?

Answer 9

inhibiting gastric acid secretion
regulation of BP - vasodil/vasocon
inhibit/activate platelet aggregation and thrombosis

Question 10

where are eicosanoids derived from?

Answer 10

arachidonic acid = 20C

Question 11

where are minor eicosanoids dervied from?

Answer 11

alpha linolenic acid obtained from diet

Question 12

what is another source of arachidonic acid?

Answer 12

PIP2
its hydrolyzed by PLA2 which removes acyl chain t 2 position
it produces arachidonic acid and leave lyso-PIP2

Question 13

what is the key enzyme in eicosanoid synthesis?

Answer 13

cyclooxygenase (COX1 and COX2)

Question 14

what does cyclooxygenase (COX1 and COX 2) do?

Answer 14

converts arachidonic acid to PGG2 – PGH2

Question 15

what do eicosanoid products depend on?

Answer 15

cell type

Question 16

what is the function of COX-1?

Answer 16

its in most tissues
basal activity - always working constantly
produces PG and TX
constituative

Question 17

what is a corticosteroid? What do they inhibit?

Answer 17

potent steroidal anti-inflammatory drug

inhibit the 1st step – inhibits PLA2 so no arachidonic acid is formed
selectively inhibit COX 2

Question 18

what omega family is arachidonic acid in?

Answer 18

omega 6

Question 19

What does COX-2 do?

Answer 19

nonconstitutive

can be induced/upregulated to become more active

Question 20

what can induce COX-2?

Answer 20

cytokines, GF, tumor promoters, endotoxins

Question 21

what inhibits the expression of COX-2?

Answer 21

glucocorticoids

Question 22

what does induction of COX 2 lead to ?

Answer 22

PG synthesis = pain, heat, redness, swelling fever

Question 23

how do non-steroidal anti-inflammatory drugs (NSAIDS) reduce inflammation?

Answer 23

inhibiting COX1 and COX 2 - reduce production of PG and TX

Question 24

some selective COX2 inhibitors have been used to treat?

Answer 24

chronic inflammation associated with disease - celebrex

Question 25

which are important to vascular health?

Answer 25

TXA2 and PGI2

Question 26

what are platelets associated with?

Answer 26

COX 1

Question 27

what is vascular endothelium associated with?

Answer 27

COX 1 and COX 2

Question 28

what does aspirin do ? How?

Answer 28

irreversibly inhibits COX 1 and COX 2 by acetylation of Serine residue in the active site!

Question 29

how does low dose aspirin reduce thrombosis?

Answer 29

reducing platelet aggregation due to decrease TX but it doesn't reduce PGI2 platelets cannot make new COX 1 enzyme - reduced TX synthesis

Question 30

endothelial cells can synthesize new COX 1 and COX 2 enzyme so they can produce what?

Answer 30

prostacyclin

Question 31

a diet rich in EPA leads to incorporation of what ?

Answer 31

20:5, omega 3 into the human phospholipid membranes

Question 32

what can be used instead of arachidonic acid by PLA2 and used for eicosanoid synthesis?

Answer 32

EPA!

Question 33

what series do PG and TX formed from EPA belong to?

Answer 33

3 series from arachidonic acid to the 2 series

Question 34

TXA3 from EPA is less what compared to TXA2 in platelet aggregation?

Answer 34

potent PGI3 and PGI2 are about the same*

Question 35

what does the net effect of PGI3 and TXA3 result in?

Answer 35

reduction of platelet aggregation/blood clotting

Question 36

how is LTA used in mast cells and eosinophils form LTC ?

Answer 36

addition of GSH - glutathione (tripeptide)

Question 37

what are the cysteinyl-leukotrienes?

Answer 37

LTC, LTD, LTE

Question 38

which are SRS-A and are much more potent than histamine?

Answer 38

cysteinyl-leurkotrienes

Question 39

how does low dose aspirin favor bettwen CV health?

Answer 39

reducing platelet aggregation by increasing the ratio of PGI2 to TXA2

Question 40

what do you want to give a patient with asthma attack and why?

Answer 40

cortisol | prevent relase of arachidonic acid

Question 41

what is the key enzyme in forming leukotrienes?

Answer 41

5-lipoxygenase