Figure 1.

Sigma non-opioid intracellular receptor 1 (σ1) expression is significantly increased on day 3 post-CCI in the mouse spinal cord dorsal horn. (A) σ1 receptor-immunoreactivity was not detected in any of the spinal sections processed with σ1-antisera pre-absorbed with a σ1 peptide overnight. (B) Western blot analysis indicated that σ1 receptor expression was significantly increased by postoperative day 1 and reached a peak level by postoperative day 3 when compared with σ1 receptor expression in sham surgery (NOR) animals (n = 9 at each time point in the CCI or sham groups). A graph depicting the change in σ1 receptor expression is shown in the upper portion, and the representative bands of σ1 receptor and β-actin expression are presented in the lower portion. (C, D) Representative photomicrographs of σ1 receptor-immunoreactive (ir) cells in the superficial layers of the ipsilateral spinal cord dorsal horn and a graph quantifying the changes in σ1 receptor expression in sham and CCI animals. On post-operative day 3, σ1 receptor expression was significantly increased in the ipsilateral superficial layers of the dorsal horn, but was also increased in the deeper laminae of CCI mice compared with the SHAM-operated controls. *P < 0.05 and **P < 0.01 as compared with those of the SHAM group. Scale bar, 200 μm.