Division of Meridian and Structural Medicine, School of Korean Medicine, Pusan National University, Yangsan 626-870, Republic of Korea.
Int J Mol Med. 2011 Oct;28(4):669-75. doi: 10.3892/ijmm.2011.728. Epub 2011 Jun 17.
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. Co-treatment with EA and dizocilpine showed a synergistic antinociceptive effect against inflammatory pain. On day two of the experiment, we examined the phosphorylation of the NMDAR NR2B subunit, of the extracellular signal-regulated kinase (ERK), p38 and of the cAMP response element-binding protein (CREB) in the ipsilateral dorsal horn of L4-5 segments by Western blot analysis. Phosphorylation of the NMDAR NR2B subunit induced by CFA was markedly inhibited by co-treatment with dizocilpine and EA, but not by dizocilpine or EA treatment alone. CFA-induced phosphorylation of the ERK was inhibited by both dizocilpine and EA, but that of p38 was inhibited by EA only. 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.
本研究在完全弗氏佐剂（CFA）诱导的疼痛模型中，考察了电针（EA）和 N-甲基-D-天冬氨酸受体（NMDAR）拮抗剂联合应用时脊髓信号通路蛋白的协同抗伤害作用。EA 刺激（2 Hz，1 mA）在穴位（足三里和三阴交）进行，每天一次，每次 20 分钟，同时鞘内注射 NMDAR 拮抗剂地卓西平（MK801）。CFA 诱导的后爪热敏感性强烈抑制地卓西平注射和 EA 刺激。EA 和地卓西平联合治疗对炎症性疼痛表现出协同的镇痛作用。在实验的第二天，我们通过 Western blot 分析检测了同侧 L4-5 节段背角中 NMDAR NR2B 亚基、细胞外信号调节激酶（ERK）、p38 和 cAMP 反应元件结合蛋白（CREB）的磷酸化。CFA 诱导的 NMDAR NR2B 亚基磷酸化被地卓西平和 EA 的联合治疗显著抑制，但地卓西平和 EA 单独治疗则没有抑制作用。CFA 诱导的 ERK 磷酸化被地卓西平和 EA 抑制，但 p38 磷酸化仅被 EA 抑制。CFA 诱导的 CREB 磷酸化被地卓西平抑制，但没有明显变化。免疫组织化学分析证实，NMDAR NR2B 亚基和 ERK 磷酸化存在显著差异。EA 和 NMDAR 拮抗剂地卓西平联合治疗可能通过脊髓 NMDAR NR2B 亚基和 ERK 的失活，在炎症性疼痛模型中产生协同的镇痛作用。
