Increased density of dopamine D-5 receptor in peripheral blood lymphocytes of migraineurs: A masker for migraine?

The expression of dopamine D-5 receptor was investigated in peripheral blood lymphocytes of 11 migraine patients and of ten healthy control subjects using a radioligand binding technique with [H-3]SCH 23390 as a ligand. [H-3]SCH 23390 is a benzazepine derivative with potent antagonist properties at the dopamine D-1-like receptors. [H-3]SCH 23390 was specifically bound to peripheral blood lymphocytes of migraineurs and control subjects in a manner consistent with the labelling of a dopamine D-5 receptor. In migraineurs a statistically significant higher density of lymphocyte dopamine D-5 receptor compared with controls was noticeable, whereas the affinity of the radioligand was unchanged. The increased density of dopamine D-5 receptor in peripheral blood lymphocytes may reflect the dopaminergic hypersensitivity displayed by migraineurs and may represent a relatively simple and reliable peripheral marker of altered dopaminergic function.