Plasma levels of substance P, neuropeptide Y and vasoactive intestinal polypeptide in patients with chronic tension-type headache

Animal and human studies have shown that substance P (SP), neuropeptide Y ( NPY) and vasoactive intestinal polypeptide (VIP) are involved in the pathop hysiology of acute and chronic pain conditions. The primary aim of the pres ent study was to compare plasma levels of SP, NPY and VIP in external jugul ar vein between patients with chronic tension-type headache and healthy con trols. The secondary aim was to examine plasma levels of these neuropeptide s in relation to headache state. In addition, we wanted to study the relati on between cranial circulation (jugular vein) and peripheral circulation (a ntecubital vein). Blood from the external jugular and antecubital vein was drawn from 20 patients with chronic tension-type headache and 20 healthy co ntrols. Plasma SP in patients, 2.0 (1.4-2.2) pmol/l, did not differ signifi cantly from plasma SP in controls, 1.7 (1.1-2.1) pmol/l, (P = 0.44). No sig nificant differences were found between SP levels on days with headache, 1. 5 (0.3-1.7) pmol/l, and SP levels on days without headache, 1.7 (1.1-1.9) p mol/l, (P = 0.06). Plasma NPY in patients, 118 +/- 3 pmol/l, did not differ significantly from plasma NPY in controls, 113 +/- 5 pmol/l, (P = 0.40). T here was no difference between NPY levels on days with headache, 120 +/- 3 pmol/l, and on days without headache, 118 +/- 3 pmol/l, (P = 0.73). VIP lev els in patients, 6 (4-7) pmol/l, did not differ significantly from VIP leve ls in controls, 5 (5-7) pmol/l, (P = 0.50). No significant differences were found between VIP levels measured on days with headache, 5 (4-6) pmol/l, a nd VIP levels measured on days without headache, 6 (4-7) pmol/l, (P = 0.81) . Plasma levels of SP, NPY and VIP did not significantly differ between the peripheral and the cranial circulation neither in patients nor in controls (P > 0.05). In summary, the present study indicates that plasma levels of SP, NPY and VIP are normal in chronic tension-type headache patients and la rgely unrelated to headache state. (C) 1999 International Association for t he Study of Pain. Published by Elsevier Science B.V.