Representative images for the ipsilateral spinal cord dorsal horns (laminae I-IV) labeled for substance P (A-C) or calcitonin gene-related peptide (D-F) immunoreactivity at day 7 after nerve root compression: sham (A, D), 10.89mN (B, E), and 98.10mN (C, F). Positive immunolabeling assessed by densitometry was confined primarily to laminae I and II. Individual densitometry measures for these images are indicated in each panel. A slight decrease in substance P staining after compression with a high load is apparent (C), and a more robust decrease is evident for CGRP immunoreactivity (F). Contralateral immunostaining followed similar trends for all groups. Scale bar in (A) = 200μm.