Melatonin and Eicosanoids

major role of melatonin

regulation of sleep and wakefulness

Where is melatonin produced?

pineal gland, located behind 3rd ventricle

melatonin is synthesized from

tryptophan with serotonin as intermediate

how does blue light suppress melatonin

photic information from retina transmitted to hypothalamus and SNS via supra-chiasmatic nucleus then to pineal gland

melatonin secretion is inhibited by

light

melatonin secretion is stimulated by

darkness

how does darkness stimulate melatonin

retinal photoreceptors release NE, which activates beta receptors in pineal gland

hoe does light inhibit melatonin

retinal photoreceptor cells become hyperpolarized, which inhibits release of NE

melatonin activates what receptors

MT1 and MT2

melatonin may have

anti-inflammatory effects on immune system and beneficial effects on cancer

abnormal circadian rhythms are implicated in mood disorders like

depression and seasonal affective disorders

bright light therapy can

decrease depression and help SAD

how does melatonin effect reproductive activity

increases during long winter nights, in spring it decreases and GnRH increases

there are decreases in melatonin at puberty due to

activation of pituitary gonadal axis

the receptors for melatonin on varies will stimulate

progesterone synthesis

eicosanoids

group of signaling molecules synthesized by oxidation of 20 carbon EFA

omega-3 EFA yield

eicosapenraenoic acid

eicosapenraenoic acid is

LESS inflammatory

omega-6 EFA yield

arachidonic acid

arachidonic acid is

PRO inflammatory

prostanoids from eicosapenraenoic acid have how many double bonds

3

leukotrienes from eicosapenraenoic acid have how many double bonds

5

prostanoids from arachidonic acid have how many double bonds

2

leukotrienes from arachidonic acid have how many double bonds

4

PGAs are

alpha, beta-unsaturated ketones

PGEs are

beta-hydroxyl ketones

PGFs are

1,3-diols

eicosapenraenoic acid major function

dampen inflammatory effects of arachidonic acid prostanoids

what prostanoids does arachidonic acid form

PG, PGI, TX

arachidonic acid major effects

stimulate inflammatory response
modulate pain and fever
inhibit gastric acid secretion
blood pressure regulation

what is a precursor to arachidonic acid

linoleic acid

cats CANT convert linoleic acid to arachidonic acid due to

low delta 6-desaturase enzyme

what releases arachidonic acid from phospholipids in cell membrane

phospholipase A2

arachidonic acid will be oxygenated by what to make prostanoids

COX1 and COX2

arachidonic acid will be oxygenated by what to make leukotrienes

5LOX

prostanoids derived from arachidonic acid major actions are

local hormone with autocrine or paracrine action
short half life
mediated by specific receptors
mediate inflammation

NSAIDs decrease

inflammation, redness, swelling, pain, and heat

NASIDS that inhibit COX1 and COX2

carprofen, banamine

NASIDs that inhibit only COX2

meloxicam, piroxicam

PGI2

vasodilation, inhibits platelet aggregation

TXA2

Vasoconstriction and stimulates platelet aggregation

PGE2

smooth muscle contraction, bronchoconstriction, pain, heat, fever