热休克预处理在大鼠脊髓损伤后细胞凋亡中的作用

Effects of Hyperthermic Preconditioning on Apoptosis after Spinal Cord Injury in Rats

目的探讨大鼠脊髓损伤后热休克蛋白70(HSP70)和氧化氮合酶(iNOS)在细胞凋亡中的作用。方法将96只大鼠分为对照组、损伤组和热休克预处理组。采用静压型脊髓损伤模型,分别在伤后6h,12h,1天,2天,3天,1周,2周和3周处死动物。用原位杂交技术检测HSP70mRNA在以上各时点的表达。同时用免疫组化法检测HSP70、iNOS在各时点的表达。运用TUNEL法检测凋亡细胞。另外,用CBS评分来评估神经功能。结果CBS评分显示,热休克预处理组的神经功能明显好于损伤组(P<0.05)。凋亡细胞数在损伤组显著高于热休克预处理组(P<0.05)。通过原位杂交和免疫组化发现,HSP70mRNA和蛋白水平在热休克预处理组明显高于损伤组(P<0.05)。免疫组化的结果还显示,iNOS的量在热休克预处理组明显低于损伤组(P<0.05)。结论热休克预处理能减轻脊髓损伤后的细胞凋亡,其机理可能同HSP70合成增加,并进一步抑制iNOS的表达有关。

Objective To study the effects of HSP 70 and iNOS on apoptosis after spinal cord injury in rats.Methods A total of 96 rats were divided into control(A), trauma(B)and hyperthermic preconditioning(C)group. Spinal cord injury(SCI) models were made by static compression.The animals were decapitated at 6h、12h、1d、2d、3d、1w、2w and 3w after injury. HSP 70 and iNOS expression inspinal cord were detected by using immumohistochemical technique . HSP 70 mRNA expression in spinal cord were detected by using in situ hybridization(ISH) method. Cells apoptosis were examined by the TUNEL reaction. Neurological outcome were evaluated by the combined behavioral score(CBS). Results Neurological outcome in the group C was significantly higher than in the group B(P< 0.05). ISH and immunohistochemistry analysis showed the level of HSP70 mRNA in the group C was significantly higher than in the group B(P< 0.05). The level of iNOS in the group C were significantly lower than in the group B(P< 0.05).In the group C , the number of apoptotic cells were significantly less than those in group B(P< 0.05).Conclusion Hyperthermic preconditioning might decrease apoptosis,which might be associated with the induction of HSP 70 synthesis,suggesting that HSP70 prevents apoptosis by interacting with iNOS.