坐骨神经分支选择性损伤模型大鼠右美托咪啶鞘内注射的镇痛作用

摘要

背景：右美托咪啶是一种高效、高选择性的α2肾上腺素受体激动剂，具有镇静、镇痛、抗焦虑等作用，对呼吸影响小。　　目的：观察鞘内注射右美托咪啶对坐骨神经分支选择性损伤模型大鼠的镇痛作用。　　方法：雄性SD大鼠36只按随机数字表法等分为正常对照组、生理盐水组和右美托咪啶组，后2组结断腓总神经和胫神经建立坐骨神经分支选择性损伤大鼠模型，右美托咪啶组在坐骨神经分支选择性损伤后14 d内每天鞘内注射右美托咪啶3μg/kg，生理盐水组大鼠注射生理盐水。　　结果与结论：与生理盐水组相比，右美托咪啶组大鼠给药后的机械性缩足反射阈值与热缩足潜伏期显著性升高(P<0.05)，脊髓背角中神经型一氧化氮合酶mRNA和蛋白的表达水平明显降低(P<0.05)，脊髓背角神经元损伤程度明显减轻，且在给药14 d时脊髓背角神经型一氧化氮合酶mRNA和蛋白的表达水平及脊髓背角神经元损伤情况与正常对照组接近。提示鞘内注射右美托咪啶可抑制脊髓背角神经型一氧化氮合酶的表达，减轻大鼠坐骨神经损伤引起的疼痛。%BACKGROUND:Dexmedetomidine is an effective high-selectivityα2-adrenoceptor agonist that has sedative, analgesic, anxiolytic effects, but slightly affects respiration. OBJECTIVE:To observe the analgesic effect of dexmedetomidine on selective damage of sciatic nerve branch in a rat model by intrathecal injection. METHODS:A total of 36 male Sprague-Dawley rats were randomly divided into normal control group, physiological saline group and dexmedetomidine group. A rat model of selective damage of sciatic nerve branch was established by knotting off the common peroneal nerve and tibial nerve in the physiological saline group and dexmedetomidine group. Rats in the dexmedetomidine group were daily injected with dexmedetomidine 3μg/kg by intrathecal injection within 14 days after injury. Rats in the physiological saline group were injected with physiological saline. RESULTS AND CONCLUSION:Compared with the physiological saline group, the mechanical withdrawal threshold and the thermal withdrawal latency were significantly increased in the dexmedetomidine group (P<0.05). Neuronal nitric oxide synthase mRNA and protein expression levels were significantly decreased in the spinal dorsal horn (P<0.05). The injury to spinal dorsal horn neurons was obviously lessened. Moreover, neuronal nitric oxide synthase mRNA and protein expression levels and the injury to spinal dorsal horn neurons were similar between 14 days after administration and normal control group. Results indicated that intrathecal injection of dexmedetomidine could inhibit the expression of neuronal nitric oxide synthase in the spinal dorsal horn and relieve the pain induced by sciatic nerve injury.