Effect of bCCI on NPY peptide staining in superficial dorsal horn. (A) Representative photomicrographs of dorsal horn immunoreactivity for Neuropeptide Y (NPY) in sham operated rats (Sham NPY) versus bCCI rats on post-ligation day 15. (B) Dorsal horn staining densitometry for NPY at various times post-ligation compared to staining in naive rats. NPY peptide showed a consistent statistically significant increase in immunoreactivity (p = 0.003; F = 11.78; df = 1; two-way ANOVA) with maximal increase on post operative day 15. Results were statistically significant for day 15 (p = 0.007; post hoc Tukey test) and day 30 (p = 0.023; post hoc Tukey test). Data points are group means +/- SEM.