鞘内预注L-NAME对神经痛大鼠脊髓内c-fos基因表达的影响

The effect of pre-emptive intrathecal administration of L-NAME on c-fos expression in rats spinal cord induced by neuropathic pain

目的 观察鞘内预先应用非选择性NOS抑制剂——L-NAME对结扎坐骨神经所致神经痛大鼠脊髓背角内c-fos基因表达的影响。方法 选择鞘内置管后无神经损伤症状的SD雌性大鼠84只,随机分为4组。A组:假手术组(n=16);B组:坐骨神经结扎组(n=24);C组:假手术前15min鞘内注射L-NAME 10μl(250μg)(n=16);D组:坐骨神经结扎前15min鞘内注射L-NAME 10μl(250μg)(n=24)。各组动物均再随机平均分为4个亚组,术后分别存活1d、3d、7d和14d。另有4只没有接受任何手术的大鼠处死后作为对照。用免疫组织化学方法观察各组大鼠同侧脊髓背角内c-fos基因的表达情况。结果 与对照组相比,在术后各测量时间点A、B两组大鼠同侧脊髓背角内c-fos基因的表达均明显增强,其中以B组最为明显(P<0.05)。鞘内预注L-NAME可明显抑制结扎坐骨神经所诱导的大鼠同侧脊髓背角内c-fos基因的表达,使D组大鼠同侧脊髓背角内Fos阳性细胞的数目在术后第3d、7d和14d分别较B组下降53.8％、57.1％和43.2％(P<0.05),但A组和C组大鼠同侧脊髓背角内Fos阳性细胞的数目没有差异。结论 一氧化氮是介导神经痛发生的一种重要介质,鞘内预先应用L-NAME可有效减少或预防神经痛的发生。

Objective To investigate the effect of intrathecal (IT) administration of L-NAME , a nonselective nitric oxide synthase (NOS) inhibitor, on c-fos expression in spinal cord induced by neuropathic pain. Methods Eighty-four female SD rats weighing 220-310g, which showed no signs of never injury 3 to 4 days after IT catheterization with the tip of catheter reaching the lumbar region, were divided into 4 groups at random: group A received IT 0.9% NaCl 10μg 15min before sham operation ( n = 16); group B received IT 0.9% NaCl 10μl 15min before ligation of sciatic nerve ( n =24); group C received IT L-NAME 10μl (250μg) 15min before sham operation ( n = 16); group D received IT L-NAME 10μl (250μg) 15min before ligation of sciatic nerve (n =24) . The animal in each group were further divided into 4 subgroups ( n = 4-6) and sacrificed on 1st, 3rd, 7th and 14th day after operation. In addition 4 rats which had received no operation of any kind were sacrificed and served as control. The c-fos expression in ipsilateral dorsal horn of spinal cord was detected by immunohistochemistry technique. Results In normal rats in control group (no IT catheterization, no operation) there were only a few fos-positive neurone (3.4± 0.9). The c-fos expression in the ipsilateral dorsal horn of spinal cord greatly increased both in group A and B. In group B there were more fos-positive neurons (FLIN) in the ipsilateral dorsal horn on the 3rd, 7th and 14th day as compare with group A. With pre-emptive intrathecal administration of L-NAME, the increase in ipsilateral c-fos expression induced by ligation of sciatic nerve was inhibited. In group D the number of fos-positive neurons in ipsilateral dorsal horn decreased by 53.8%, 57.1% and 43.2% on the 3rd, 7th and 14th day after operation as compare with group B. On the 1st day afteroperation there was no difference-in FLIN in the ipsilateral dorsal horn between group B and D. Conclusion Nitric oxide plays an important role in mediating the neuropathic pain which can be effectively attenuated or prevented by pre-emptive IT administration of L-NAME.