胰岛素对大鼠急性脊髓损伤后细胞凋亡及诱导型一氧化氮合酶、环氧化酶-2表达的影响

Effect of insulin on neuronal apoptosis and the expression of inducible nitricoxide synthase and cyclooxygenase-2 after acute spinal cord injury in rats

目的:研究胰岛素对大鼠急性脊髓损伤(SCI)后细胞凋亡及相关炎症因子诱导型一氧化氮合酶(in-duciblenitricoxidesynthase,iNOS)、环氧化酶-2(cyclooxygenase-2,COX-2)表达的影响。方法:60只SD大鼠随机分为损伤对照组和胰岛素治疗组,每组30只,采用改良Allen's法建立SCI模型。SCI后30min内治疗组经腹腔注射普通速效胰岛素1IU/kg·d+50%葡萄糖1g/kg·d,分3次给药,每8h1次,连续给药7d;对照组给予等量生理盐水。伤后8h、1d、3d、7d、14d每组各处死6只动物取材,采用原位末端标记(TUNEL)和免疫组织化学染色方法观察脊髓细胞凋亡及iNOS、COX-2表达的变化。结果:SCI后各时间点胰岛素治疗组TUNEL阳性细胞数明显少于损伤对照组,差异有显著性(P<0.05或P<0.01);胰岛素治疗组iNOS、COX-2的表达率均明显低于对照组,差异有显著性(P<0.05或P<0.01)。结论:胰岛素对大鼠急性脊髓损伤有保护作用,抑制炎症因子iNOS、COX-2的表达可能是其作用机制之一。

Objective：To study the effect of insulin on neuronal apoptosis and the expression of inducible nitricoxide synthase（iNOS） and cyclooxygenase-2（COX-2） on experimental rats with acute spinal cord injury. Method：60 SD rats were divided into two groups：control group and insulin group,each group has 30 rats.The SCI animal model was established with Allen＇s method.ln insulin group,common short-acting insulin was given through intraperitoneal injection （1 IU/kg·d＋50%GS lg/kg·d）, while the same dose of normal saline was administrated in control group.The rats were killed on the 8h,1d,3d,Td,14d postoperatively（n=6 at each time point）.Apoptosis neurons were labeled with TUNEL,and the expression of iNOS and COX-2 were tested with immunocytochemistry technique.Result：On 8h,ld,3d,Td,14d after operation,the number of TUNEL staining positive cells in the insulin group was less than in control group （P〈0.05 or P〈0.01）.Immunohistochemical staining revealed that the expression of iNOS and COX-2 was lower in insulin group than in control group at 8h,1d,3d,7d,14d after injury （P〈0.05 or P〈0.01）.Conclusion：Insulin can protect injured spinal cord through inhibiting the expression of iNOS and COX-2,which may be one of the protective mechanisms of insulin against spinal cord injury.