Platelet substance P and 5-hydroxytryptamine in migraine and tension-type headache

Levels of substance P (SP) and 5-hydroxytryptamine (5-HT) in platelets were measured in 25 patients with migraine, 31 patients with tension-type headache (TH) and 27 healthy controls. The mean concentration of SP in platelets was 355.3 pg/10(9) platelets in patients with migraine, 290.8 pg/10(9) platelets in patients with TH and 180.8 pg/10(9) platelets in the controls. The concentrations of platelet SP in the migrainous patients and in the TH patients were significantly higher than those in the controls. The mean concentration of 5-HT in platelets was 619.7 ng/10(9) platelets in patients with migraine, 579.3 ng/10(9) platelets in patients with TH and 811.9 ng/10(9) platelets in the controls. The concentration of platelet 5-HT in the patients with TH was significantly lower than that in the controls. The platelet SP/5-HT ratio in the migrainous patients and in the TH patients were significantly higher than that in the controls. There was significant negative correlation between the concentrations of platelet SP and those of platelet 5-HT. These results may support the hypothesis that SP released from the terminals of the trigeminal nerves causes migraine either through direct actions on the vessels or by releasing 5-HT from the platelets. The high levels of platelet SP in TH patients might reflect release of SP from the pain sensory system.