Objective: To investigate the effect of saikosaponin a (SSa) on the levels of immune inflammation in rats with acute spinal cord injury and its possible mechanism.
Methods: Seventy-two Sprague Dawley rats (weighing, 220-250 g) were randomly divided into sham operation group (group A), spinal cord injury group (group B), and SSa treatment group (group C) respectively, 24 rats in each group. The spinal cord injury model was induced by using the Allen's method in groups B and C; the spinous process and vertebral plate at both sides were cut off by lamina excision to expose the spinal cord in group A. The rats were given intraperitoneal injection of 10 mg/kg SSa in group C and equal volume of normal saline in group B at immediate after injury. The spinal cord tissue was harvested from 18 rats of each group at 24 hours after operation to measure the levels of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) by ELISA, to detect the expressions of nuclear factor κB (NF-κB) P65, NF-κB P-P65, and aquaporin 4 (AQP4) by Western blot and to observe the morphology of spinal cord by HE staining. The motor function of the lower limbs was evaluated by BBB score and tiltboard experiment in 6 rats at 1, 3, 7, 14, 21, and 28 days after injury.
Results: The BBB score and tiltboard experiment maximum angle were significantly higher in group A than groups B and C at each time point ( P<0.05) and in group C than group B at 14, 21, and 28 days after operation ( P<0.05). ELISA test showed that the concentrations of TNF-α and IL-6 were significantly lower in group A than groups B and C, and in group C than group B ( P<0.05). Western blot results showed that the protein expression levels of NF-κB P65, NF-κB P-P65, and AQP4 were significantly lower in group A than groups B and C, and in group C than group B ( P<0.05). HE staining demonstrated normal neurons of the spinal cord and no obvious lesion in group A; neuronal cells were observed in the injured area of group B, with hemorrhage, neutrophil infiltration, and nerve cell edema in the injured area; the neuronal cells were visible in the spinal cord of group C, with microglia mild hyperplasia, and the pathological changes were improved when compared with group B.
Conclusion: SSa has neuroprotective effects on acute spinal cord injury in rats by inhibiting NF-κB signaling pathway and AQP4 protein expression and reducing inflammation response and edema.
目的: 探讨柴胡皂苷 a（saikosaponin a，SSa）对大鼠急性脊髓损伤早期机体免疫炎性水平的影响，并研究其可能存在的影响机制。.
方法: 取健康成年雌性 SD 大鼠 72 只，体质量 220～250 g，随机分为假手术组（A 组）、脊髓损伤组（B 组）、SSa 处理组（C 组），每组 24 只。A 组仅咬除棘突和椎板暴露脊髓；B、C 组利用改良 Allen 重物打击法制作急性脊髓损伤模型，造模后即刻 C 组给予大鼠腹腔注射 10 mg/kg SSa，B 组注入等量生理盐水。术后 24 h 每组处死 18 只大鼠并取出脊髓组织，采用 ELISA 法检测 TNF-α 和 IL-6 浓度，Western blot 检测 NF-κB P65、NF-κB P-P65 和水通道蛋白 4（aquaporin 4，AQP4）蛋白表达水平，HE 染色观察脊髓组织形态；每组其余 6 只大鼠分别于术后 1、3、7、14、21、28 d 采用 BBB 评分和斜板实验评价大鼠双下肢运动恢复情况。.
结果: 术后各时间点 A 组 BBB 评分和斜板实验最大角度均显著高于 B、C 组（ P<0.05），术后 14、21、28 d C 组上述指标显著高于 B 组（ P<0.05）。ELISA 检测示，A 组 TNF-α、IL-6 浓度显著低于 B、C 组，C 组显著低于 B 组，差异均有统计学意义（ P<0.05）。Western blot 检测示，A 组 NF-κB P65、NF-κB P-P65 和 AQP4 蛋白表达水平显著低于 B、C 组，C 组显著低于 B 组，差异均有统计学意义（ P<0.05）。HE 染色示，A 组脊髓中神经细胞正常，无明显病变；B 组脊髓中损伤部位可见神经元细胞，损伤处有出血、中性粒细胞浸润、神经细胞水肿；C 组脊髓中可见神经元细胞，小胶质细胞轻度增生，病变较 B 组好转。.
结论: SSa 通过抑制 NF-κB 信号通路和 AQP4 蛋白的表达，减轻急性脊髓损伤后机体炎性反应和组织水肿，从而具有一定保护神经的功能。.
Keywords: Saikosaponin a; aquaporin-4; inflammation response; neuroprotection; rat; spinal cord injury.