17β-雌二醇对大鼠脊髓损伤后神经细胞凋亡的影响

目的研究17β-雌二醇（E2）对大鼠脊髓损伤后神经细胞凋亡的影响。方法SD大鼠随机分为假手术组（A组）、磷酸盐缓冲液对照组（B组）及E2治疗组（C组）。应用重物打击法建立大鼠急性脊髓损伤模型（A组仅行椎板切除术），分别于伤后7、14、21及28d，按照改良Tarlov评分法和Rivlin斜板试验观察脊髓功能恢复情况。伤后6、24h和3、7、14、28d分别处死动物取材，HE染色观察病理变化，TUNEL法和流式细胞术检测细胞凋亡情况。结果TUNEL法和流式细胞术检测结果均表明大鼠脊髓损伤后存在细胞凋亡。TUNEL法显示细胞凋亡在伤后3d达高峰，C组伤后24h、3d及7d凋亡细胞比率均显著低于B组（P〈0．01或P〈0．05）；流式细胞术显示细胞凋亡率在伤后7d达高峰，C组细胞凋亡率在24h以后各观察时间点均显著低于B组（P〈0．01或P〈0．05）。14d以后，C组脊髓神经功能恢复显著好于B组（P〈0．01或P〈0．05）。结论E2能减少继发性脊髓损伤后细胞凋亡，促进脊髓功能的恢复。

Effects of 17 beta-estradiol on neuron apoptosis after spinal cord injury in rats

Objective To investigate the effects of 17 beta-estradiol on neuron apoptosis after spinal cord injury(SCI) in rats.Methods The SD rats were randomly divided into 3 groups: sham-operated group(group A),phosphate buffer saline group(group B) and 17 beta-estradiol group(group C).Rat model of SCI was established,while animals in sham-operated group underwent a T9 laminectomy without weight-drop injury.The neurofunction of spinal cord was evaluated by modified Tarlov score and Rivlin platform test at 7 d,14 d,21 d and 28 d after injury.The animals were sacrificed at 6 h,24 h,3 d,7 d,14 d and 28 d respectively after injury.The lesion areas of the spinal cord were cut for morphological studies by hematoxylin and eosin staining.Cell apoptosis was examined using the TUNEL assay and the flow cytometry.Results Neuron apoptosis was noted by the TUNEL assay and the flow cytometry after SCI in rats,and peaked at 3 d with TUNEL after SCI,while at 7 d with the flow cytometry.Compared with group B the apoptotic rate in group C was significantly decreased at the time points of 24 h,3 d and 7 d(P<0.01 or P<0.05).After 14 d,the neurofunction of the spinal cord was better in group C than in group B(P<0.01 or P<0.05).Conclusion 17 beta-estradiol can reduce the numbers of apoptotic cells and promote the nerve function recovery after SCI.