鞘内注射氯胺酮对慢性神经痛大鼠脊髓背角一氧化氮合酶的影响

Effect of intrathecal ketamine on nitric oxide synthase activity in the spinal dorsal horn in a rat model of neuropathic pain

目的 探讨鞘内注射(IT)氯胺酮对慢性坐骨神经挤压损伤大鼠(CCI)脊髓背角一氧化氮合酶(NOS)活性的影响。方法 雄性SD大鼠36只,随机分为6组(n=6):假手术组(组Ⅰ);CCI组(组Ⅱ);氯胺酮组:于术前30min、术后1、2、3d分别IT氯胺酮12.5μg(组Ⅲ)、50μg(组Ⅳ)、100μg(组Ⅴ)、300μg(组Ⅵ)。按Bennett法制作CCI模型,以von-Frey filaments测定触痛及冷刺激反应,术后14d断头取腰段脊髓,以紫外分光光度计测定脊髓背角NOS活性。结果 与组Ⅰ相比,术后第7、14天组Ⅱ、组Ⅲ痛阈下降,冷刺激反应升高(P<0.05或0.01),组Ⅳ、Ⅴ、Ⅵ痛阈及冷刺激反应无显著性变化(P>0.05);与组Ⅱ比较,组Ⅳ、Ⅴ、Ⅵ的痛阈升高,冷刺激反应下降(P<0.05或0.01)。与组Ⅰ相比,组Ⅱ、Ⅲ脊髓背角NOS活性升高(P<0.01),而组Ⅳ、Ⅴ、Ⅵ则无显著性变化(P>0.05);与组Ⅱ比较,组Ⅳ、Ⅴ、Ⅵ髓背角NOS活性明显下降(P<0.01)。组Ⅲ、Ⅳ、Ⅴ、Ⅵ痛阈、冷刺激反应和NOS活性组间比较差异无显著性(P>0.05)。结论 N0/NOS系统参与了CCI大鼠痛敏的形成,此过程与NMDA受体有关。

Objective To evaluate the effect of intrathecal ketamine on nitric oxide synthase (NOS) activity in the spinal dorsal horn via a rat model of sciatic constriction injury(SCI). Methods Thirty-six male SD rats weighing 160-180g were randomly divided into six groups(n = 6 in each group): group Ⅰ sham operation; group Ⅱ SCI; group Ⅲ-Ⅵ intrathecal ketamine + SCI. In group Ⅰ right sciatic nerve was exposed but no ligature was placed around sciatic nerve. In group Ⅱ-Ⅵ four ligatures were placed around the right sciatic nerve and hed without obstructing the blood supply of the nerve. In group Ⅲ -Ⅵ ketamine 12. 5μg (group Ⅲ ),50μg (group Ⅳ ), 0μg (group Ⅴ ) or 300μg (group Ⅵ ) was given intrathecally 30 min before and 1,2 and 3 days afer surgery. On the 7th and 14th day after operation thermal and mechanical hyperalgesia were measured with ice- cold water and von-Frey filaments. The animals were decapitated 14 days after SCI. The I_(4-6) lumbar spinal cord was immediately removed and the spinal dorsal horn was dissected on ice and homogenized. The homogenate was centrifuged at 3 500 r/min for 10 min and the protein content was determined. NOS achvity in the spinal dorsal horn was measured using ultraviolet spectrophotometer. Results In group Ⅱ and Ⅲ pain threshold was significantly lowered and NOS activity significantly increased compared with those in group Ⅰ(sham operation) (P<0 .01 ). There was no significant difference in NOS activity between group Ⅰ and group Ⅳ, V, Ⅵ (P >0 .05),but there was signilicant difference in NOS activity between group Ⅱ and group Ⅳ, Ⅴ, Ⅵ (P< 0.01 ). Conclusion NO/ NOS may contribute to the development of nearepathic pain in rats induced by sciatic nerve constriction and NMDA receptor may be involved in the process.