Up-regulation of NR2B receptors in PAG after injury. (A) Western blot results showed that the expression level of GluR1 and NR2B receptors, but not NR2A receptor, was increased in the PAG after CFA injection. Hyp reversed expression level of GluR1 and NR2B receptors. (B) Summary of expression of NR2A, NR2B, GluR1 receptors in the PAG after CFA-injection. Values were significantly different from saline control ** p < 0.01; from CFA-injected alone # p < 0.05.