PKA levels are elevated in the spinal trigeminal nucleus in response to CGRP. Spinal cord sections were obtained from control animals (CON), animals 2 hours post CGRP injections, or animals 24 hours post CGRP injection. (A) Images of spinal cord tissues stained for PKA are shown in the top panels. Magnification bar = 50 μm. The same sections costained for PKA and DAPI are displayed in the bottom panels. (B) The average fold change ± SEM of PKA staining intensity from control values is reported (n = 3). * P < 0.05 when compared to control values.