中文摘要：

目的探讨苯并（a）芘[B（a）P]致神经元凋亡中线粒体膜电位和胞质中细胞色素C（CytC）蛋白变化。方法选用新生1—3d的SD大鼠分离大脑皮质进行神经元培养，在细胞培养第5天，选取生长良好的同批次神经细胞，以B（a）P同时加S9分别对神经元染毒，使B（a）P终浓度分别为0、10、20、40μmol／L。继续培养40h，应用AnnexinV和碘丙啶（PI）双染法进行细胞凋亡的检测，加入Rh123，应用流式细胞仪测定细胞线粒体膜电位，免疫印迹（Western blot）法测定神经元胞质中CytC蛋白的表达。结果随着B（a）P浓度的增加，神经细胞的早期、晚期凋亡率逐渐增高，中、高剂量组与对照组比较，差异均有统计学意义（P〈0．05或P〈0．01），趋势检验表明，早期凋亡率增高具有剂量依赖性。随B（a）P染毒浓度的增加，神经细胞线粒体膜电位下降，低、中、高剂量组神经细胞膜电位分别为5．02±1．32、4．36±1．26、3．15±1．47，与对照组（8．89±2．18）比较，差异均有统计学意义（P〈O．05），线粒体膜电位与早期凋亡率之间呈负相关（r=-0．763，P〈0．05）；随着B（a）P浓度的增加，胞质中CytC蛋白的表达逐渐升高，CytC蛋白表达与早期凋亡率间呈正相关（r=0．831，P〈0．01）。结论B（a）P可致神经细胞凋亡，线粒体膜电位降低以及CytC的释放可能是诱发凋亡的主要因素。

英文摘要：

Objective To investigate the changes of mitochondria membrane potential and cytoplas- mal cytochrome C as the mechanism of neuron apoptosis induced by B （a）P. Methods Primary neurons were dissociated from cerebral cortex of 1-3 days old SD rats and cultured with DMEM incubator at 37 ℃. After 5 days＇ cultivation, the neurons were added S9 and B （a）P, and the concentrations of treated B （a）P were 0, 10, 20 and 40 I.tmol/L respectively. After administering of B （a）P, the neurons were cultivated for 40 hours. Apoptosis rate was measured by flow cytometry using Annexin V-FITC and propidium iodide （PI） stain- ing, and the changes in mitochondrial potential （△ψm） were tested with Rhodamine fluorescence （R2123） technique. Preparation of cytosolic extracts by centrifugation. Western blotting analysis was used to evaluate the level of cytochrome C of cytoplasm. Results The apoptotic rate of neuron increased in both the middle dose group and the high dose group compared with controls, and had a dose-response tendency with the con- centration of B （a）P. Moreover mitochondrial potential decreased in a dose dependent manner. There was a negative correlation between △ψm and the apoptotic rate of neurons （r=-0.763, P〈0.05） ; Western blotting analysis showed cytoplasmic cytochrome C level increased significantly, which was positively related with neu- ron apoptosis （r=0.831, P〈O.01 ）. Conclusion Loss of mitochondria membrane potential and increase of cytoplasmal cytochrome C may be the main cause of neuron apoptosis induced by B（a）P.