Eicosanoids

Question 1

Phases of inflammation

Answer 1

Acute phase of inflammation includes infiltration by granulocytes (neutrophils) followed by monocytes that mature into macrophages. This process causes the four cardinal signs of inflammation: rubor (redness), calor (heat), tumor (swelling), and dolor (pain)

Question 2

Four cardinal signs of inflammation

Answer 2

Rubor (redness), calor (heat), tumor (swelling) and dolor (pain)

Question 3

Prostaglandins

Answer 3

synthesis dramatically increases during inflammation
proinflammatory and may be important in resolution of inflammation
inhibitors of prostaglandin synthesis are anti-inflammatory
Prostaglandins are members of the eicosanoids

Question 4

Examples of eicosanoids

Answer 4

Prostaglandins, thromboxanes, and leukotrienes

Question 5

How are eicosanoids made?

Answer 5

They are made from 20 C polyunsaturated fatty acids
They are in cell membrane phospholipids and released by phospholipases
They are made by most cell types (except RBCs)
The precursor is arachidonic acid (which can be synthesized from linoleate) (Some prostaglandins use EPA (eicosapentaenoic acid) as a precursor)

Question 6

Precursor of eicosanoids

Answer 6

arachidonic acid (which can be synthesized from linoleate)
some prostaglandins use eicosapentaenoic acid (EPA) as a precursor (linolenic acid can be used to synthesize eicosapentaenoic acid)

Question 7

Synthesis of arachidonic acid from linoleate

Answer 7

delta6-desaturase uses linoleoyl-CoA, oxygen, and NADH (and a proton) to make gamma-linolenoyl-CoA (and water and NAD+). This is elongated in the ER and uses malonyl CoA to make Dihomo-gamma-linolenoyl-CoA. Delta6-desaturase then uses oxygen and NADH (and a proton) to make Arachidonoyl-CoA

Question 8

The desaturase for the synthesis of arachidonic acid is located in ___.

Answer 8

cytochrome b5

Question 9

Triene:Tetraene ratio

Answer 9

marker for essential fatty acid deficiency
>0.4 indicates deficiency
Mead’s acid:Arachidonic

Question 10

Linoleic acid can be a precursor for ___.

Answer 10

EPA (eicosapentaenoic acid)

Question 11

Omega 3 and omega 6 fatty acids both compete for the same ______.

Answer 11

delta 5 and delta 6 desaturases

Important because ingestion of more omega 6 fatty acids may lead to more inflammation

Question 12

Release of arachidonic acid induced by ____.

Answer 12

binding to a receptor (e.g. cytokines)

Phospholipase A2 releases arachidonic acid in response to cellular signals that trigger making eicosanoids

Question 13

What does phospholipase C activity do?

Answer 13

releases phosphatidyl inositol (PIP) (which according to the notes has something to do with a second signal that creates DAG, which can also break down into arachidonic acid)