serotonin Flashcards
syntesis of serotonin
from essential amino acid tryptophan
5HT formed by tryptophan hydroxylase (rate limiting in periphery but not in CNS b/c of low tryptophan levels)
serotonin is synesized in most tissues that contain it except blood platelets
converted to melatonin in the pineal gland
metabolism of serotonin
converted by monamine oxidase and aldehyde dehydrogenase to 5-hydroxy indole acetic acid
neuronal action terminated by reuptake (SERT) and then converted to 5HIAA
serotonin distribution
Enterochomaffin cells of GIT: hold the largest amount of serotonin
Blood platelets: 8%, stored in vesicles w/ ATP, no synthesis, removes serotonin from blood, helps platelet aggregation
CNS: cell bodies in raphenuclei- 2% (project to areas of CNS, sythesis storage and release fast, affected by many psychoactive drugs)
Gastro intestinal system and serotonin
Enterochromaffin cells
both neuronal and non neuronal synthesis and storage
Slow release, causes contraction of smooth muscle of GIT
Emesis can be induced by 5-HT3 receptors in brain and GIT
Carcinoid syndrome- serotonin secreting tumors- severe diarrhea and asthma
CV system and serotonin
typically vasoconstriction in blood vessels (via 5HT2 R) or 5HT1D
Vasodilation in coronary arteries, sk muscle, and cutaneus
Bezold-Jarisch reflex- serotinin–> vagal nerve–> bradychardia, hypotension, hypoventilation
CNS and serotonin
Neurotransmitter- cell bodies in midbrain raphe nucle
Involved in sensory perception, sleep, temp regulation, neuroendocrine regulation, learning and memory, pain, drug abuse, emesis, mental illness
lysergic acid diethylamide (LSD)
potent hallucinogen, full or partial agonist on 5-HT2 receptors
buspirone
partial agonist 5-Ht 1a receptors, used as an anti-anxiety
sumatriptan
agonist at 5ht 1D and 1B receptors
inhitbits release of vasoactive peptides
treats migrains
SE nausea, vomiting, angina, dizziness, flushing
lorcaserin
obesity, selective 5HT2C receptor agonist in the hypothalamus–> activates POMC–> satiety
Fluoxetin
SSRI
Major depressive disorder, OCD, panic attac
Phenelzine
MAO inhibitor
depression and narcolepsy
SE: food induced HTN crisis
Duloxetine
Serotonin-norepinephrine reuptake inhibitor
major depressive disorder, and pain
cyproheptadine
5HT 2 receptor antagonist and histamine H1 antagonist
skin alergies, pruritus and urticaria and carcinoid
Ondansetron
5-HT3 receptor antagonist
chemotherapy-induced nausea treatment
acts on GI and brain
IV oral and transdermal
