Fig. 4

The mRNA and protein levels of opioid receptors in the spinal cords among the different groups. The groups were as follows (n = 6 per group): control group (1 mL isotonic saline), M group (10 mg/kg morphine), D1 group (10 mg/kg dezocine), D2 group (1 mg/kg dezocine), MD1 group (10 mg/kg morphine + 10 mg/kg dezocine), and MD2 group (10 mg/kg morphine + 1 mg/kg dezocine). Data are expressed as the mean ± SEM. One-way analysis of variance (ANOVA) was used, followed by the Bonferroni test. *P < 0.05 compared with the control group. #P < 0.05 compared with the morphine group