FTY720对急性脊髓损伤大鼠神经功能及血脊髓屏障的影响

Effects of FTY720 on neurological function and blood-spinal cord barrier of rats with acute spinal cord injury

目的观察新型免疫抑制剂FTY720对急性脊髓损伤后大鼠神经功能和血脊髓屏障的影响。方法成年SD大鼠144只,随机分为4组(n=36)。正常对照组(NG):不做任何处理;假手术组(SO):单纯咬除椎板暴露脊髓,不予损伤处理;损伤对照组(HS):脊髓右半侧横切损伤后腹腔注射生理盐水;FTY720治疗组(FTY720):脊髓右半侧横切损伤后30min给予腹腔注射FTY720[1mg/(kg·d)],连续7d。术后不同时间点行行为学检测,包括BBB运动功能评分和水平网格检测;行神经电生理运动诱发电位(MEP)N1波和感觉诱发电位(SEP)P1波潜伏期检测;对脊髓组织行苏木精-伊红(HE)染色及Evans Blue(EB)血脊髓屏障渗透性检测。分析FTY720治疗效果。结果半横切损伤后,HS组和FTY720组大鼠损伤侧脊髓神经功能下降,至28d时仍未恢复至NG组和SO组水平。行为学检测和神经电生理检测结果显示,FTY720组大鼠运动功能恢复速度比HS组更快;损伤7、14、28d时,两组大鼠BBB评分和SEP P1波潜伏期检测差异有统计学意义(P<0.05);损伤14、28d时,两组大鼠水平网格检测和MEP N1波潜伏期检测差异有统计学意义(P<0.05)。组织学检测结果显示,各时间点NG组和SO组大鼠脊髓结构均完整;损伤14d时,FTY720组脊髓损伤处慢性炎症细胞浸润,胶质化反应程度小于HS组;损伤28d时,FTY720组损伤处空洞残存面积小于HS组,再生纤维排列较HS组有序。血脊髓屏障渗透性检测结果发现,损伤后7d内,HS组和FTY720组大鼠血脊髓屏障EB渗出量较NG组和SO组明显增加;各时间点FTY720组EB渗出面积均小于HS组(P<0.05),其中损伤3d时差异最为明显。结论 FTY720能显著降低脊髓损伤急性期血脊髓屏障渗透性,有效促进急性期后神经功能的恢复,为损伤组织提供一定的神经保护作用。

Objective To investigate the effects of a novel immunomodulator FTY720 （Fingolimod） on nerve function and blood-spinal cord barrier （BSCB） of rats with acute spinal cord injury. Methods One hundred and forty-four adult Sprague- Dawley （SD） rats were randomly divided into four groups with 36 each： normal control group （NG Group）： rats without any treatment; sham-operated group （SO Group）： rats＇ spinal cords were exposed by laminectomy without injury; hemisection group （HS Group）： rats underwent spinal cord hemisection followed by intraperitoneal injection of normal saline; FTY720 treatment group （FTY720 Group）： rats underwent spinal cord hemisection followed by intraperitoneal injection of FTY720 [ lmg/（kg.d）] for 7 days. The neurological function was assessed by Basso Beatlie Bresnahan （BBB） scores, grid walking, N1 and P1 delay of motor evoked potential （MEP） and somatosensory evoked potentials （SEP）, histological evaluation with light microscope with HE staining, and determination of blood-spinal cord barrier permeability with EB at different time points after injury. Results The nerve function of rats in HS group and FTY720 group was impaired after hemisection injury without signs of recovery up to Day 28 after damage as compared with NG group or SO group. The recovery of motor function in FTY720 treatment group was earlier than in HS group. The BBB scores, the results of grid walking test, and the latent period of SEP-P1 showed statistically significant difference between FTY720 group and HS group from Day 7 to 28 after injury （P〈0.05）. Comparing the pathological picture at Day 14 and Day 28 after in）ury, the number of chronic inflammatory cells, the degree ofglial cell reaction, and the size of syringomyelia cavities in gray matter in FTY720 group were significantly less than those in HS group. In additionj the leakage of EB from the damaged BSCB increased in HS group and FTY720 group than in NG group and SO group through 7 days after in）ury （P〈0.01）, while at each time point the leakage of EB was less in FTY720 group than in HS group （P〈0.05）, and the most significant difference was observed on Day 3 after injury. Conclusion FTY720 can lower the permeability of blood-spinal cord barrier at acute phase of spinal cord in）ury, effectively promotes the recovery of nerve function after acute in）ury phase and it provides certain potential neuroprotective effects.