N-乙酰半胱氨酸对大鼠神经元凋亡及神经病理性疼痛的影响

Effect of N-acetylcysteine on rat neuron apoptosis and neuropathic pain

目的观察N-乙酰半胱氨酸(NAC)对坐骨神经结扎大鼠脊髓神经元凋亡及神经病理性疼痛的影响。方法60只Sprague-Dawley大鼠随机分为对照组(Sham组)、NAC组和0.9%氯化钠溶液组(NS组)。NAC组和NS组大鼠采用Bennettand Xie模型行大鼠右侧坐骨神经结扎术,NAC组大鼠每日腹腔注射NAC300mg/kg,NC组大鼠腹腔注射等量0.9%氯化钠溶液。检测超氧化物歧化酶(SOD)的变化,同时以caspase-3免疫组织化学及末端脱氧核苷酸转移酶介导的dUTP缺口末端标记(TUNEL)技术观察脊髓神经元凋亡的情况,以热痛阈作为痛觉过敏反应的指标,比较NAC组与NS组神经元凋亡及热痛阈的差异。结果术后1、3、7、10d,Sham组大鼠的热痛阈显著高于NAC组和NS组(P值均<0.05),NAC组又显著高于NS组(P值均<0.05)。术后7d,NAC组和NS组的脊髓SOD水平降至最低,分别为(20.099±5.265)和(21.171±7.616)U/mg,均显著低于Sham组的(35.088±3.616)U/mg(P值均<0.05),其余时间点各组脊髓SOD水平的差异均无统计学意义(P值均>0.05)。Sham组大鼠脊髓caspase-3的表达较少,NAC组和NS组大鼠脊髓Ⅰ、Ⅱ层caspase-3阳性神经元细胞明显增加,但NAC组明显少于NS组。NAC组的神经元凋亡细胞数显著高于Sham组(P<0.05),但显著低于NS组(P<0.05)。结论NAC可抑制坐骨神经结扎大鼠脊髓神经元凋亡,同时也可缓解热痛觉过敏反应。NAC可能作为一种新的治疗神经病理性疼痛的药物。

Objective To investigate the effect of N-acetylcysteine （NAC） on CCI-induced neuropathic pain and neuron apoptosis in rats. Methods Sixty Sprague-Dawley rats were randomly divided into Sham group, NAC group and normal saline （NS） group. Neuropathic pain was produced in the latter 2 groups by ligation of right sciatic nerve according to the technique described by Bennett and Xie. Rats in NAC group were given NAC （300 mg/kg per day） and those in NC group were given the same dose of normal saline. Changes of serum superoxide dismutase （SOD） expression were measured in all groups. Caspase-3 expression was detected by immunohistochemistry and apoptosis of neurons was detected by TUNEL. The pain thresholds to thermal stimulation of the right paw were compared between NAC group and NS group. Results The pain thresholds in Sham group were significantly higher than those of NAC group and NS group at 1, 3, 7, and10 days after operation （all P〈 0.05）, and those of group NAC were significantly higher than those of group NS （all P〈0.05）. On the 7th day after operation, the spinal SOD level in NAC and NS groups reached the lowest （[20. 099± 5. 265] and [21. 171±7.616] U/mg, respectively）, which were significantly lower than that of the Sham group （[35.088± 3. 616] U/mg, both P〈0.05） the spinal SOD levels were not significantly different at other time points among the 3 groups （all P〉0.05）. Spinal caspase-3 expression was low in the Sham group the expression in the I , spinal layers in rats of NAC and NS group was obviously increased, but that of the NAC group was less than that of the NS group. The neuron apoptosis in NAC group was significantly higher than that of the Sham group （ P〈0.05）,but was lower than that of the NS group （ P〈0.05）. Conclusion It is concluded that NAC can inhibit neural apoptosis in the spinal cord dorsal horn and alleviate thermal hyperalgesia induced by CCI, indicating that NAC may be a potential candidate for treatment of neuropathic pain.