目的：探讨右美托咪定（Dex）鞘内注射对手术后切口痛大鼠的镇痛效果及其可能的镇痛机制。方法将40只健康雄性 SD 大鼠采用随机数字表法分为4组，每组10只：假手术组（Ⅰ组）不作任何处理，切口痛组（Ⅱ组）行左足底切开手术，生理盐水组（Ⅲ组）先鞘内注射生理盐水后行左足底切开手术，右美托咪定组（Ⅳ组）先鞘内注射Dex 0．75μg·kg－1后行左足底切开手术。观察大鼠术后2 h 机械缩足反射阈值（MWT）、热缩足潜伏期（TWL）和脊髓背角磷酸化环腺苷酸反应原件结合蛋白（pCREB）表达的变化。结果与Ⅰ组比较，Ⅱ、Ⅲ、Ⅳ组 MWT 均降低，TWL 均缩短，脊髓背角 pCREB 表达均增加（P ＜0．05）；与Ⅱ、Ⅲ组比较，Ⅳ组 MWT 升高，TWL 延长，脊髓背角 pCREB 表达减少（P ＜0．05）。结论鞘内注射右美托咪定可抑制大鼠切口痛，镇痛机制可能与其引起的脊髓背角 pCREB 的表达增加有关。%ABSTRACT:Objective To investigate the analgesic effect of intrathecal dexmedetomidine on postoperative incisional pain in rats and its possible mechanism of action.Methods Forty healthy male SD rats were randomly divided into four groups of 10 each:sham operation group(groupⅠ):rats received no treatment;incisional pain group(group Ⅱ):rats received left plantar inci-sion;normal saline group(group Ⅲ):rats received left plantar incision after intrathecal injection of normal saline;dexmedetomidine group(group Ⅳ):rats received left plantar incision after in-trathecal injection of dexmedetomidine 0.75 μg·kg-1 .Mechanical withdrawal threshold(MWT), thermal withdrawal latency(TWL)and phosphorylated cAMP response element-binding protein (pCREB)expression in the spinal dorsal horn were observed 2 hours after operation.Results Compared with group Ⅰ,MWT and TWL decreased and pCREB expression in the spinal dorsal horn increased in groups Ⅱ,Ⅲ and Ⅳ (P < 0.05).Compared with group Ⅱ or Ⅲ,MWT and TWL increased and pCREB expression in the spinal dorsal horn decreased in group Ⅳ(P <0.05). Conclusion Intrathecal dexmedetomidine may alleviate incisional pain in rats and the mechanism of action of dexmedetomidine may involve the increase in pCREB expression in spinal dorsal horn.
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