PMC

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.

The expression level of tyrosine phosphorylation of NR2B in superficial spinal cord in each group. The L4-L5 spinal cords for analysis were collected at 48 h after the surgery. Proteins were extracted from the dorsal half of the L4-L5 spinal cord.(A) Representative western blot for tyrosine phosphorylation of NR2B (py-NR2B) in the superficial dorsal horn at the L4-L5 spinal cord; (B) quantification of NR2B tyrosine phosphorylation in each group. Data from five groups, each using six rats. Data are expressed as means ± SD.* P < 0.01 vs group C, ^# P < 0.01 vs group I, ^△P < 0.01 vs group R.

Typical photomicrographs representing tyrosine phosphorylation of NR2B immunoreactive neurons in the superficial dorsal horn. The L4-L5 spinal cords for analysis were collected at 48 h after the surgery. In preparations of control group, hardly any tyrosine phosphorylation of NR2B immunoreactive neurons was found in the dorsal horn region (A). In preparations of rats with incision receiving saline or ketamine, moderate tyrosine phosphorylation of NR2B immunoreactive neurons was obtained in the superficial dorsal horn (Laminae I-II) at the L4-L5 spinal cord, ipsilateral to the incision (B and C). The number of tyrosine phosphorylation of NR2B immunoreactive neurons were drastically upregulated in rats receiving infusion of remifentanil (D), which was remarkably inhibited by pretreatment with ketamine (E). Magnification: × 100. Scale bar = 100 μm.

Effects of remifentanil on PWTL during the postoperative period and the intervention of ketamine. Ketamine (10 mg/kg, 0.1 ml) or saline was subcutaneously injected 30 min before surgery. Under sevoflurane anesthesia, remifentanil (0.04 mg/kg, 0.4 ml) or saline was subcutaneously infused in the absence or presence of the right hind paw incision during a period of 30 min. PWTL was evaluated at 24 h before incision and at 2 h, 6 h, 24 h and 48 h after surgery. Number of rats per group was twelve. Data are expressed as means ± SD. * P < 0.01 vs baseline, ^# P <0.01 vs group C, ^▽P <0.05 vs group I, ^△P < 0.01 vs group R.

Effects of remifentanil on PWMT during the postoperative period and the intervention of ketamine. Ketamine (10 mg/kg, 0.1 ml) or saline was subcutaneously injected 30 min before surgery. Under sevoflurane anesthesia, remifentanil (0.04 mg/kg, 0.4 ml) or saline was subcutaneously infused in the absence or presence of the right hind paw incision during a period of 30 min. PWMT was evaluated at 24 h before incision and at 2 h, 6 h, 24 h and 48 h after surgery. Number of rats per group was twelve. Data are expressed as means ± SD. *P < 0.01 vs baseline, ^# P < 0.01 vs group C, ^▽P < 0.01 vs group I, ^△P < 0.01 vs group R.