17β-雌二醇对大鼠脊髓损伤后神经保护作用的研究

Study of neuroprotection of 17 beta-estradiol after spinal cord injury in rats

目的:探讨17β-雌二醇(E2)对大鼠脊髓损伤(SCI)后的神经保护作用及其机制。方法:应用改良的Allen′s重物打击法建立大鼠急性脊髓损伤模型,将大鼠随机分为两组:A组(PBS对照组)和B组(E2治疗组),每组42只,B组造模成功后15min及24h腹腔注射E2(4.0mg/kg,以PBS溶解),A组在相同时间给予等量无菌PBS。分别于伤后7d、14d、21d及28d,应用改良Tarlov评分法和Rivlin斜板试验评价大鼠脊髓神经功能恢复情况。于伤后6h、24h、3d、7d、14d及28d时处死动物,以损伤部位为中心取材,HE染色观察脊髓组织病理变化,TUNEL法染色检测细胞凋亡,免疫组化染色检测caspase-3、Bcl-2的表达情况。结果:从伤后14d起,B组Tarlov评分和斜板试验角度与A组相比差异有显著性(P<0.01)。TUNEL法检测表明,大鼠SCI后存在细胞凋亡,3d时达高峰,与caspase-3的表达基本一致,B组伤后24h、3d及7d时凋亡细胞比率显著低于A组(P<0.01或P<0.05)。免疫组化结果显示B组伤后24h、3d、7d、14d及28d时caspase-3表达低于A组(P<0.01或P<0.05),而Bcl-2表达高于A组(P<0.01或P<0.05)。结论:E2能促进大鼠SCI后的神经功能恢复,具有一定的神经保护作用;E2可能是通过减少SCI后继发性细胞凋亡的机制发挥作用的。

Objective：To investigate the neuroprotection and mechanisms of 17 beta-estradiol after spinal cord injury （SCI） in rats.Method：Rat model of SCI was established with a modified Allen＇s method.The experimental rats were randomly divided into two groups：group A,phosphate buffer saline （PBS） group and group B,17 beta-estradiol experimental group.Each group consisted of 42 rats.Rats in group B received 4.0 mg/kg of 17 beta-estradiol,which was dissolved in PBS at 15min and 24h post-injury,while rats in group A were treated with an equal volume of PBS at the same time point.The neurofunction of spinal cord was evaluated by modified Tarlov score and Rivlin platform test at 7d,14d,21d and 28d after injury respectively.The animals were sacrificed at 6h,24h,3d,7d,14d and 28d respectively after injury.The lesion areas of the spinal cord were dissected for morphological studies by hematoxylin and eosin staining.Cell apoptosis was examined using the TUNEL assay and the expression of caspase-3 and Bcl-2 were detected using immunohistochemistry method.Result：From the 14th day after treatment,the neurofunction of the spinal cord was significantly better in group B than that in group A（P〈0.01）.Apoptotic cells were noted in rats after SCI,and peaked at 3rd day after SCI,which was consistent with the expression of caspase-3.The apoptotic rate in group B decreased significantly as compared with that in group A at the time points of 24h,3d and 7d （P〈0.01 or P〈0.05）.In group B,the expression of caspase-3 decreased significantly,while Bcl-2 significantly improved as compared with that in group A at the time points of 24h,3d,7d,14d and 28d after SCI （P〈0.01 or P〈0.05）.Condusion： 17 beta-estradiol can reduce the numbers of apoptotic cells and promote the nerve function recovery after SCI.