Eicosanoids

Question 1

What are the physiological activities of eicosanoids?

Answer 1

• swelling and inflammation
• response to wounds or foreign stimuli
• allergic reactions
• platelet activation

Question 2

What are the fatty acid precursors?

Answer 2

alpha-linolenic acid–>omega 3 FAs

linoleic acid–>omega 6 FAs

Question 3

What are the major pathways of eicosanoid synthesis?

Answer 3

1. Cyclooxygenase pathway (COX): makes prostacyclins and thromboxanes
2. Lipooxygenase pathway (LOX): makes leukotrienes, HETE derivatives, diHETE derivatives, and Lipoxins
3. Cytochrome P450 pathways: mono hydroxy FA derivatives

Question 4

What is the mode of action for eicosanoids?

Answer 4

Stimulate actions in autocrine or paracrine manner (locally)

-bind to specific receptors on target cells, many are GPCRs

Question 5

What are the classes of Eicosanoids?

Answer 5

1. COX: thromboxanes, prostaglandins
2. LOX: hydroperoxy ETE, hydroxy ETE, Dihydroxy ETE, lipoxins, leukotrienes
3. Cytochrome P450: 20 HETE

Question 6

What do leukotrienes do?

Answer 6

• have amino acid residue
• bronchoconstriction
• activates endothelium and chemokine production by mast cells
• overproduction causes asthmatic attacks and induces anaphylactic shock

Question 7

What is the metabolic fate of eicosanoids?

Answer 7

short lived, thought to be metabolized in lungs