机械性脑白质损伤后皮层神经元凋亡的证据及其分布特征

目的　探讨细胞凋亡在机械性脑白质损伤后皮层神经细胞病理变化中的作用及其分布特征。方法　雄性健康SD大鼠 3 6只随机分为假手术组 (1 2只 )和模型组 (2 4只 ) ,用模型组动物制作大脑皮层下横切模型。于致伤后不同时间处死动物 ,用TUNEL原位末端标记和常规病理组织学方法观察损伤区及相应皮层神经细胞变化的性质和规律。结果　致伤后横切处出血 ,损伤组织内神经元出现坏死改变 ,胶质细胞增多。大脑皮层Ⅱ Ⅴ层神经细胞多出现萎缩改变。伤后 1 2d时 ,相应皮层内即出现散在早期凋亡神经元 ,随后逐渐增多 ,7d后又趋减少 ,伤后 1 9d皮层内仍可检出凋亡神经元。在损伤区凋亡神经元少见 ,可见部分胶质细胞凋亡。结论　脑白质损害时 ,损伤相应部位皮层神经元主要表现为凋亡。在损伤区 ,神经元和胶质细胞主要表现为坏死。皮层内凋亡神经元主要分布于第Ⅱ Ⅴ层 ,其时间分布呈一单峰状曲线 ,凋亡峰出现在伤后第 7d前后 ,至少持续 1 9d。

Detection of cortical-neuron apoptosis after mechanical subcortical transection in rats

Objective To investigate the presence, role and characteristics of apoptotic cell death in the cortex after mechanical white matter injury. Methods Thirty Six SD rats received mechanical subcortical transection and were killed at different time points (from 12?h to 19?d) of post injury, and the brains were obtained. The nature of cell death in the lesion and in the cortex were observed by HE staining, buffered methylen blue staining and TUNEL In situ nick end labeling. Results Histopathological examination showed lesion gap hemorrhage, neuronal cell necrosis and glial cell proliferation in and around the lesioned site, while in the layers Ⅱ～Ⅴ of the corresponding cortex many neurons shriveld withered with only few of them showing sign of necrosis. TUNEL In situ end labeling detected some apoptotic glial cells in the lesion and its surrounding tissues, but few apoptotic neurons. In the cortex, apoptotic neurons could be detected as early as 12?h post injury, and the number increased with time, peaked at 7 days, and declined afterwards. On the 19th day, they could still be detected. Apoptotic glial cells were hardly seen in the cortex. Meanwhile, apoptotic neurons were also detected in both hippocampals and in the contralateral cortex symmetrical to the injured site. Conclusion The main pathological change of cortical neurons in not necrosis but apoptosis after mechanical white matter injury. The apoptotic neurons anatomically located in the corresponding cortical layers Ⅱ～Ⅴ, and timely presentd a single wave curve with its number peakeing at 7 days post injury. In the lesioned and surrounding tissues,the pathological changes of neuronal and glial cells are mainly necrosis accompanying some apoptotic glial cells.