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