International journal of molecular medicine
-
This study examined the synergistic antinociceptive effects associated with signaling pathway proteins of the spinal cord in a complete Freund's adjuvant (CFA)-induced pain model when electroacupuncture (EA) and a N-methyl-D-aspartate receptor (NMDAR) antagonist were administered in combination. EA stimulation (2 Hz, 1 mA) was needle-delivered for 20 min once daily at acupoints corresponding to Zusanli and Sanyinjiao with intrathecal injection of the NMDAR antagonist dizocilpine (MK801). Thermal sensitivity of the hindpaw induced by CFA was strongly inhibited by dizocilpine injection and EA stimulation. ⋯ CFA-induced phosphorylation of CREB was inhibited by dizocilpine, but did not show marked changes. Immunohistochemical analyses confirmed that there was a significant difference in the NMDAR NR2B subunit and ERK phosphorylation. It is possible that the combined treatment with EA and the NMDAR antagonist dizocilpine resulted in synergistic antinociceptive effects in an inflammatory pain model via the inactivation of both the NMDAR NR2B subunit and ERK of the spinal cord.