Eicosanoids Flashcards
What is the main function of eicosanoids?
They play critical roles in inflammation, the vasculature and in gastrointestinal, reproductive, renal and respiratory function
What are the 4 types of eicosanoids?
-prostoglandins
-thromboxanes
-leukotriens
-lipoxins
How do eicosanoids function?
They act as local hormones with very short half lives, functioning mostly through G-protein-linked receptors
What are the fatty acid precursors of eicosanoids?
essential fatty acids: linoleic acid or alpha linolenic acid
or directly from arachidonic acid
What are the two enzymatic pathways of eicosanoid synthesis?
cycloocygenase
lipoxygenase
Which pathway yields which type of eicosanoid?
-cycooxygenase: prostaglandins and thromboxanes
-lipoxygenase: leukotrienes and lipoxins
Which enzyme is associated with arachidonic acid derived eicosanoids?
cycloocygenase (COX) 1 & 2
What is the difference between COX 1 and COX 2
COX-I is in many cell types, and is responsible for normal housekeeping functions, homeostasis, regulation of blood flow to the kidney and GI tract
COX-2: expressed in inflammatory cells
What are cyclooxygenase products?
Prostaglandins H2 which is converted to PGD2, PGE2, TXA2, TXB2, prostacyclin (PGI2)
What is the function of prostacyclin (PGI2)?
vasodilation, increase renal blood flow, bronchodilation, inhibits platelet aggregation
What is the function of PGE2?
decrease gastric acid secretion, renal blood flow and vasodilation, uterine contraction, GI smooth muscle contraction
What is the function of PGF2alpha
uterine contration, bronchoconstriction
How do NSAIDS function?
They inhibit cyclooxygenases
What is the main function of thromboxane A2?
opposes prostayclin (PGI2), vasoconstriction and encourages platelet aggregation
Where are lipoxygenases produced?
white blood cells, lung, immune cells
