serotonin

serotonin(5-hydroxytriptamin)
DISTRIBUTION:
1-G.I.T
2-BLOOD
3-CNS
PHARMACOLOGICAL EFFECTS
G.I.T : regulate the peristalsis reflexes and colonic motility
Located in enterochromaffin cells act as sensor transducer
10% of serotonin in intestine act as a neurotransmitter
smooth muscle
Uterus and bronchial smooth muscles contracted by the 5-hydroxytriptamin
blood vessele
Both arteries and veins are usually constricted by 5- HT
Activation of 5-HT1receptors causes constriction of large intracranial vessels
platelets
5-HT release from platelets causes platelets aggregation by acting on receptor 5-HT2A in addition to vasoconstriction effect.
nerve ending
5-HT stimulate pain mediating sensory nerve ending by acting on 5-HT3 receptors .
Also 5-HT inhibit transmitter release from adrenergic neurons
CNS
5-HT excites some neurons and inhibit others ,it act presynaptically to inhibit release from nerve terminal
Biosynthesis and metabolism
Tryptophan ------------5-hydroxytryptophan

5-hydroxytryptophan ----------5-HT
5-HT--------------5-hdroxyindolacetic acid
receptors and location
serotonin agonists
1-buspiron
2-dexfenfluramin
3-sumatriptan,naratriptan,
rizartiptan and zolmitriptan
4-cisaprid and tegserod
serotonin antagonists
1-cyproheptadine
2-ketanserin and ritanserin
3-ondansetron ,granisetron,and tropisetron
4-dihydroergotamin, methysergid
ergot alkaloids
1-ergotamin and dihydroergotamin
2-ergometrin(ergonovin)
3-methysergid
4- bromocript
Drugs used in the prophylaxis of migrain
1-?-blockers drug
Propranolol,metoprolol,atenolol
2-tricyclic antidepressant
Amitriptylin
3-calcium channel blockers
Verapamil
4-antisiezures drugs
divalproex