Dural application of CGRP primes female rats to a subthreshold nitric oxide donor. Facial withdrawal thresholds were measured in females before and after either 1 pg CGRP (n = 9) or vehicle pH 7.4 SIF (n = 7) applied to the dura. At 24 h following dural CGRP or dural vehicle, all rats were given 0.1 mg/kg SNP (i.p.). Two-way ANOVA indicated significant effects of SNP in the CGRP-treated group with no response to SNP in the vehicle-treated group. Significant differences in the means of each group were determined by ANOVA followed by Bonferroni post hoc test (F_(6,98) = 9.171). These data are represented as means ± SEM; ***p < .001, ****p < .0001).