Fig. 4. Western blot analysis illustrating the change in ς1receptor (Sig-1R) expression in the ipsilateral spinal cord dorsal horn at various time points after chronic constriction injury (CCI) versus sham rats ( upper panel in A and also B ). After nerve injury (n = 5 at each time point in the CCI or sham groups), Sig-1R expression was significantly increased by postoperative day 1 (D1) and reached a peak level by postoperative day 3 (D3) when compared with Sig-1R expression in sham surgery animals (n = 5; lower panel in A ). Sig-1R expression in the ipsilateral dorsal horn decreased to levels seen in sham-treated animals by 7 days after injury (D7), and there were no statistical differences between CCI and sham animals at the 7-day time point. B = before (a day before surgery). *P < 0.05 as compared with those of sham surgery rats .