大鼠急性脊髓损伤后IL-18和Caspase-1的表达

The Study on Expression of IL-18 and Caspase-1 in Rats with Acute Spinal Cord Injury

目的探讨急性脊髓损伤(SCI)后脊髓组织中IL-18、Caspase-1表达的临床意义。方法将60只成年雄性SD大鼠随机分为假手术组(30只)和脊髓损伤组(30只),分别在手术后3h、6h、12h、3d、7d进行取材,依取材时间不同再细分为5个亚组,每个亚组6只。假手术组只做全椎板切除而不用Allen’s重物打击法造成脊髓损伤;脊髓损伤组进行全椎板切除,并采用改良的Allen’s重物打击法造成脊髓损伤建立大鼠急性脊髓损伤模型。采用BBB评分法分别在造模后1、3、7d对所有实验大鼠的后肢运动功能进行评分。脊髓组织病理学采用HE染色观察,Western blot测定IL-18、Caspase-1蛋白的表达量。结果假手术组大鼠麻醉清醒后活动自如,脊髓损伤组大鼠在麻醉清醒后即可出现双侧后肢完全瘫痪;假手术组大鼠术后1、3、7d的BBB评分均高于脊髓损伤组(P均<0.05)。脊髓组织病理学观察,假手术组光镜下可见神经元细胞排列整齐,结构形态规则,无炎性细胞出现,脊髓组织中IL-18、Caspase-1蛋白在各时间点表达相对稳定;而脊髓损伤组损伤段脊髓灰质出现片状出血,随时间延长会出现灰质结构被破坏、细胞空泡变性,大量神经元细胞死亡、出现大量的炎性细胞;脊髓损伤组大鼠IL-18和Caspase-1蛋白的表达在伤后3h均呈高表达,在伤后3d达到高峰;且各时间点均高于假手术组(P均<0.01)。结论 IL-18和Caspase-1蛋白在SCI的高表达,提示它们可能参与了SCI后的继发性损伤。

Objective To investigate the clinical significance of expression of IL-18 and Caspase-1 in rats after acute spinal cord injury（SCI）. Methods Sixty adult male SD rats were randomly divided into sham-operated group（30 rats）and spinal cord injury group（30 rats）. Samples were taken at 3 hours,6 hours,12 hours,3 days and 7 days after operation. The rats were subdivided into 5 subgroups according to the sampling time,6 rats in each subgroup. Spinal cord injury was induced only by total laminectomy in sham operation group without Allen＇s weight percussion method; spinal cord injury group not only underwent total laminectomy,but also by modified Allen＇s weight percussion method to establish acute spinal cord injury model in rats. BBB scoring method was used in all the experiments 1,3 and 7 days after modeling. The hind limb movement function was scored in rats at 3 h,6 h,12 h,3 d and 7 d after injury. The expression of IL-18 and Caspase-1 was detected by Western blot and HE staining. Results The rats in sham-operated group were able to move freely after awake from anesthesia,and the rats in spinal cord injury group were able to have complete paralysis of both hind limbs after awake from anesthesia. The BBB scores of rats in sham-operated group were higher than those in spinal cord injury group at 1,3 and 7 days after operation（P〈0.05）. Histopathological observation of the spinal cord showed that the neurons in the sham-operation group were arranged orderly, with regular morphology and no inflammatory cells. The expression of IL-18 and Caspase-1 protein in the spinal cord was relatively stable at all time points,while in the spinal cord injury group,there was slice hemorrhage in the injured spinal cord and grey matter nodule with time prolonging. The expression of IL-18 and Caspase-1 protein in spinal cord injury group was high at 3 h after injury and reached the peak at 3 d after injury,and was higher than that in sham operation group at all time points（P〈0.01）. Conclusion The high expression of IL-18 and Caspase-1 may be involved in secondary injury after SCI,and may be one of the major factors of secondary spinal cord injury.