How does methysergide protect against migraine despite of antagoinizing the effect of serotonin (=vasodilation) ??

Question

rawanhamdi · Answer

in migraine there is also dilatation of cranial vessels!!!

anonymous · Answer

Although methysergide is an ergot alkaloid, it is a weak vasoconstrictor and oxytocic
Serotonin is considered to be the chemical mediator controlling headaches, by either directly or indirectly lowering the pain threshold. Platelet serotonin levels have been shown to increase before a Migraine attack
Methysergide is a highly competitive antagonist of serotonin (5-HT) in the periphery and may be a(( serotonin agonist))note note)) in the CNS. 
Thus, the serotonin agonist activity of methysergide in the CNS appears to contribute to the prophylaxis of vascular headaches

anonymous · Answer

methysergide has been shown to inhibit or block the effects of serotonin, a substance which may be involved in the mechanism of vascular headaches. Serotonin has been variously described as a central neurohumoral agent or chemical mediator, as a “headache substance” acting directly or indirectly to lower pain threshold Suggestions have been made by investigators as to the mechanism whereby methysergide produces its clinical effects, but this has not been finally established.