Immunohistochemical analysis. The L4-L5 spinal cords for analysis were collected at 48 h after the surgery. The mean optical density of NR2B tyrosine phosphorylation (py-NR2B) in the superficial dorsal horn (Laminae I-II) at the L4-L5 spinal cord are summarized. Data from five groups, each using six rats. For each rat, the mean optical density of NR2B tyrosine phosphorylation was obtained by averaging the values from six sections. Data are expressed as means ± SD. * P < 0.01 vs group C, # P < 0.05 vs group I, △
P < 0.05 vs group R.