Calcitonin gene-related peptide levels during nitric oxide-induced headache in patients with chronic tension-type headache

It has been proposed that nitric oxide (NO) induced headache in primary hea daches may be associated with release of calcitonin gene-related peptide (C GRP). In the present study we aimed to investigate plasma levels of CGRP du ring headache induced by the NO donor glyceryl trinitrate (GTN) in 16 patie nts with chronic tension-type headache and 16 healthy controls. The subject s were randomly allocated to receive 0.5 mug/kg/min GTN or placebo over 20 min on two headache-free days. Blood samples were collected at baseline, 10 , 20 and 60 min after start of infusion. Both patients and controls develop ed significantly stronger immediate headache on the GTN day than on the pla cebo day and the headache was significantly more pronounced in patients tha n in controls. There was no difference between the area under the CGRP curv e (AUC(CGRP)) on GTN vs. placebo day in either patients (P = 0.65) or contr ols (P = 0.48). The AUC(CGRP) recorded on the GTN day did not differ betwee n patients and controls (P = 0.36). Both in patients and controls, CGRP lev els changed significantly over time, on both the GTN and placebo days (P < 0.05). The present study indicates that NO-induced immediate headache is no t associated with release of CGRP.