Effect of bCCI on Neurokinin-1 Receptor (NK-1R) staining in superficial dorsal horn. (A) Representative photomicrographs of dorsal horn immunoreactivity for Neurokinin-1 Receptor (NK-1R) in sham operated rats (Sham NK 1R) versus bCCI rats on post-ligation day 15. Scale bar represents 100 μM. (B) Dorsal horn staining densitometry for NK-1 R at various postoperative days expressed as a percentage of naive rats. NK-1 receptor showed a consistent statistically significant increase in immunoreactivity, (p < 0.001; F = 145.5; df = 1; two-way ANOVA) with maximal increase on day 15 (increase of greater than 400% of naïve control). Results were statistically significant for all time points studied. [Day 15 and 30 (p < 0.001; post hoc Tukey test); 45 day (p = 0.003; post hoc Tukey test) and day 90 (p = 0.027; post hoc Tukey test)]. Data points are group means +/- SEM.