Melatonin and Eicosanoids

Stimulators of melatonin

1. Darkness

What supresses melatonin?

Blue light (photic information from retina transmitted to hypothalamus and SNS via supra-chiasmatic nucleaus, then to pineal gland)

Inhibitor of prostanoid formation

NSAIDs

Major role of melatonin

Regulation of sleep and wakefulness

Omega-6 EFAs are derived from ___________ and have _____________ inflammatory effects

arachidonic acid; pro

Omega-3 EFAs are derived from _________________ and have __________ inflammatory effects

eicosapentaenoic acid; less

Actions of melatonin

1. Activates M1 and M2 receptors 2. Regulates sleep, mood 3. Affects sexual maturation and reproduction

3 steps in the synthesis of eicosanoids

1. Dietary precursors of arachidonic acid 2. Phospholipase A release AA from phospholipids in cell membrane 3. AA oxygenated by COX1/COX2 (make prostanoids) or 5LOX (to make leukotrienes)

Omega-6 EFAs are dervied from arachidonic acid which can turn into ________________

1. Prostanoids with 2 double bonds 2. Leukotrienes with 4 double bonds

Omega-3 EFAs are derived from eicosapentaenoic acid which can turn into ________________

1. Prostanoids with 3 double bonds 2. Leukotrienes with 5 double bonds

Major actions of prostanoids derived from AA

1. Smooth muscle contraction, brachoconstriction, pain, heat, fever (PGE2) 2. Vasodilation, inhibits platelet aggregation (PGI2) 3. Vasoconstriction, stimulates platlet aggregation (TXA2)

What is the relevance of Melatonin in veterinary medicine?

1. Treat alopecia X in dogs (may decrease GnRH, which decreases LSH/FSH effects on adrenal androgen precursors) 2. Decreases anxiety and seizure activity

Eicosanoids are a group of signaling molecules synthesized by oxidation of _______________

20-carbon essential FA

NSAIDs that only inhibit COX1 and COX2

Aspirin, carprofen, ibuprofen, etc.

Major function of the eicosapentaenoic acid cascade

Dampen inflammatory effects of arachindonic acid prostanoids

Inhibitors of melatonin

Light

What can't cats convert?

Linoleic acid to arachidonic acid

The secretion of melatonin is stimulated by darkness. Retinal photoreceptors release....

NE

Where is melatonin produced?

Pineal gland

NSAIDs that only inhibit COX2

Previcox, metacam, etc. (less side effects)

The eicosapentaenoic acid cascade forms mostly _____________

Prostanoids

What is melatonin synthesized from?

Tryptophan, with serotonin as intermediate