HTR1B and migraine disorder: Given the identical chemistry and thus pharmacology of DHE and11C-DHE, the broad receptor profile, including 5HT1A, 5HT1B, 5HT1Dreceptors, α-adrenoceptors and dopamine D2receptors (Tfelt-Hansenet al., 2000) and the lack of binding in hippocampus and raphe nuclei, areas with the greatest density (Hallet al., 1997) of the high affinity DHE receptors (Tfelt-Hansenet al., 2000), it seems clear the blood–brain barrier is not altered in migraine, at least not for DHE.