α-[11C] methyl-L tryptophan-PET as a surrogate for interictal cerebral serotonin synthesis in migraine without aura

BackgroundAlteration in central serotonin biology has been implicated in migraine, and serotonin (5-HT) agonists have been available for more than a decade in the treatment of that condition. ObjectivesTo test this hypothesis, we studied invivo using positron-emission tomography (PET) and -[C-11] methyl-L-tryptophan (-[C-11]MTrp) as a surrogate marker of cerebral 5-HT synthetic rate before and after administration of eletriptan in migraine and control subjects. MethodsSix nonmenopausal female migraine subjects with migraine without aura (MoA) and six nonmenopausal age-matched female control subjects were scanned at baseline and after oral administration of 40mg of eletriptan. Migraine subjects at the time of PET had to have been headache free for a minimum of three days. Images of (-[C-11]MTrp) brain trapping were colocalized with individual MRI images in three dimensions and analyzed. ResultsThere was no difference in baseline cerebral global 5-HT synthesis between migraine and control subjects. After administration of eletriptan, there was a striking global reduction in cerebral 5-HT synthesis (K*) in the migraine group and in 22 regions of interest (ROIs). In control subjects, no significant changes were found in global cerebral 5-HT synthesis (K*) or in any of the ROIs. ConclusionsThese findings suggest in migraine an interictal alteration in the regulation mechanisms of cerebral 5-HT synthesis.