Histamine/5-HT/AA Flashcards
where are histamine receptors found
-Mainly Skin, lungs and GI
proportional to mast cell presence
-some non mast in brain and stomach
Allergic mediation
IgE binds allergen which activated intracellular Ca2+ release, then causing histamine release
H1 receptor
G- protein important for allergy/ inflammation
-Skin (itching and wheal/ flare)
-Increase HR
-contract SM in lungs, GI and uterus
H2 receptor
G-protein
stimulate gastric acid secretion
histamine receptor antagonist action
usually inverse agonists as receptor has basal activity
5-HT synthesis
produced from tryptophan and broken down by MAO
5-HT receptor location
enterochromaffin cells in GI
Platelets
CNS
5-HT physiological effects
Constrict large BV, Dilate small
Contract SM in lungs/uterus
Increase GI motility
Stimulate clotting
nociceptor activation
5-HT pathophysiolocal effects
migraine
pulmonary hypertension
carcinoid syndrome
nausea
5-HT receptors
7 types all G protein coupled except for 5-HT3 ion channel
5-HT1B
Gi/o linked
CNS, BV elsewhere
-presynaptic inhibition
-pulmonary vasoconstriction
5-HT1D
Gi/o linked
-CNS, BV
-Cerebral vasoconstriction
-locomotion effects
5-HT2A
Gs linked
CNS,PNS,SM and platelets
-Sm contraction in GI/lungs
-platelet aggregation
-constrict large BV, dilate Small
Migraine steps
premonitory (sensitivity)
aura (pain/ visual)
headache
postdromal phase (fatigue)
migraine 3 theories
Vascular (constriction then dilation)
Brain (wave of depolarization)
neuroinflammation (trigeminal nerve activation)
