Platelet ³H ketanserin binding in tension-type headache

Abstract

Objective: The present study was undertaken to investigate the alterations in platelet 5-HT₂ receptor binding in patients with tension-type headache. Background: Serotonin (5-HT) has an important but complex role in pain modulation. The involvement of serotonin in tension-type headache has been investigated by studying serotonin in peripheral blood, but results have been inconclusive. There are, however, only a few investigations in which the status of platelet serotonin transporters has been studied by ³H imipramine and ³H paroxetine. The present study was undertaken to investigate alterations in platelet 5-HT_2A receptors using ³H ketanserin as a ligand. Methods: Platelet 3H ketanserin binding was studied in 14 patients with tension-type headache and in 15 healthy controls. The binding characteristics, equilibrium dissociation constant and maximal number of binding sites were determined by Scatchard analysis. Results: There was no change in the equilibrium dissociation constant in the patients with headache as compared to the control group, but subgroup analysis revealed that patients with tension-type headache with a headache index of less than 360 had a significantly lower equilibrium dissociation constant as compared to those with a headache index of more than 360; there was a significant correlation between the equilibrium dissociation constant and the headache index. A significant decrease was observed in the maximal number of binding sites in tension-type headache. No correlation was observed between the maximal number of binding sites and age, duration of illness, or headache intensity. Conclusions: The findings of the present study show that there is a decrease in the number of binding sites of 5-HT_2A receptors in some patients with tension-type headache, suggesting postsynaptic serotonergic dysfunction and the involvement of serotonin in that group.