miR-24对大鼠脊髓损伤后运动功能的影响

Effect of miR-24 on the Motor Function after Spinal Cord Injury in Rats

目的观察miR-24对大鼠脊髓损伤后运动功能恢复的影响。方法健康成年Sprague-Dawley大鼠60只,随机分为miR-24组、对照组和假手术组(Sham组),每组20只。Sham组只暴露脊髓,不打击。对照组和miR-24组采用Allen’s方法损伤大鼠T9脊髓节段,制备脊髓损伤动物模型。造模成功后30 min,miR-24组鞘内注射agomir-24(0.5 nmol/L,5μL),对照组鞘内注射等量的agomir对照,每日1次,共3次。采用BBB评分法分析大鼠后肢运动功能,实时PCR检测脊髓组织中miR-24表达水平,HE染色观察大鼠脊髓组织病理形态学变化,实时PCR和Western blot检测脊髓组织中Bim mRNA和蛋白的表达水平。结果与Sham组相比,对照组大鼠损伤后1、3、7和14 d脊髓组织中miR-24表达均降低,其中3、7及14 d差异有统计学意义(P<0.05)。与对照组相比,miR-24组大鼠损伤后3、7和14 d BBB评分均显著升高(P<0.05);损伤后1和3 d脊髓损伤形态学均有改善,损伤后3 d改善更明显;损伤后1和3 d脊髓组织Bim mRNA和蛋白的表达水平均显著降低(P<0.05)。结论 miR-24可能通过抑制Bim的表达,促进脊髓损伤大鼠运动功能的恢复。

Objective To observe the effect of miR-24 on the motor function after spinal cord injury （SCI） in rats, and explore the related mecha- nism. Methods A total of 60 healthy adult Sprague-Dawley rats were randomly divided into control group, sham group and miR-24 group with 20 rats in each group. SCI model was made by Allen＇s mode at the level of the 9th thoracic vertebra. 30 min after SCI model was made, mrs in miR-24 group were given agomir-24 （0.5 nmol/L, 5 μL） daily for 3 times by intrathecally injection, while rats in control group were given an equal volume of agomir control. The motor function was evaluated by BBB score. The m/R-24 expression in spinal cord tissue was detected by real-time PCR. The pathological change of spinal cord tissue was observed by HE staining. The Bim mRNA and protein expression in spinal cord tissue were detected by real-time PCR and Western blot, respectively. Results Compared with that in sham group, miR-24 expression in spinal cord tissue of rats from con- trol group was decreased at 1 d, 3 d, 7 d and 14 d after injury, and the difference was significant at 3 d, 7 d and 14 d （P 〈 0.05）. Compared with that in control group, BBB score in rats from miR-24 group was significantly increased at 3 d, 7 d and 14 d after injury （P 〈 0.05）. The morphology of spinal cord injury in rots from miR- 24 group was improved at 1 d, 3 d after injury, and the effect was more significantly at 3 d after injury. The mRNA and protein expression of Bim in spinal cord tissue of rats from miR-24 group were all decreased significantly after injury （P 〈 0.05 ）. Con- dusion miR-24 promote the recovery of motor fimction of rats with spinal cord injury by inhibiting the expression of Bim.