Fig. 5. Graphs illustrating the effect of intrathecal administration of the ς¹receptor antagonist BD1047 (30 nmol; n = 5) from days 0 to 5 after surgery on the chronic constriction injury (CCI)–induced increase in  N -methyl-d-aspartate receptor NR1 expression (  A ) and NR1 phosphorylation (pNR1) (  B ) in each region of the dorsal horn. The number of NR1-immunoreactive (ir) and pNR1-ir neurons in spinal dorsal horn was significantly increased on day 5 after CCI surgery ( *P < 0.05, **P < 0.01 as compared with that of sham surgery animals [n = 5]). Intrathecal daily injection of BD1047 during induction phase of neuropathic pain significantly blocked the CCI-induced increase in the number of NR1-ir neurons (  A ) and pNR1-ir neurons (  B ) in the nucleus proprius and in the neck region of the ipsilateral spinal cord dorsal horn (#  P < 0.05, ## P < 0.01 as compared with vehicle-treated CCI animals [n = 5]). SDH = superficial dorsal horn (laminae I and II); NP = nucleus proprius (laminae III and IV); NECK = neck of dorsal horn (laminae V and VI) .