N-甲基-N-亚硝脲诱导大鼠视网膜光感受器细胞凋亡

目的 探讨N一甲基一N一亚硝脲(MNu)对大鼠视网膜光感受器细胞毒性作用的机制。 方法 将生后50 d的雌性SD大鼠30只分别按60 mg／kg的剂量一次性腹腔注射MNu。在注射MNU 12、24、48、72 h和7 d后，颈椎脱臼法处死大鼠，取出眼球，做病理切片。另6只生后50 d的雌性sD大鼠为正常对照。用TuNEI一试剂盒和透射电镜检测光感受器细胞凋亡；免疫组织化学方法检测MNU作用不同时间视网膜细胞内增生细胞核抗原(PcNA)、弹性蛋白和胶质纤维酸蛋白(GFAP)的表达。 结果 MNu作用后极部视网膜光感受器细胞12、24、48、72 h和7 d后的凋亡指数分别是(33．6±2．3)％、(46．5±5．7)％、(20·l±5·3)％、(8-2±3·6)％和(2．O±O．8)％。在MNu作用后24 h，大部分光感受器细胞出现核固缩；24 h后，内颗粒层及内颗粒层和脉络膜之间有PcNA表达，72 h达高峰，7 d后明显减少；24 h后，内颗粒层和外颗粒层开始出现GFAP和弹性蛋白的阳性表达，72 h达高峰，7 d后明显减少。 结论 MNu可选择性地诱导视网膜光感受器细胞发生凋亡及引起Mnller细胞增生。 （中华眼底病杂志，2004，20：33-36）

Photoreceptor cell apoptosis of rat′s retina induced by N-methyl-N-nitrosourea

Objective To investigate the mechanism of the toxic effect of N methyl N-nitrosourea (MNU) on photoreceptor cell apoptosis of rat’s retina. Methods Thirty 50-day-old female Sprague-Dawley ( SD ) rats were intraperitoneally injected with MNU (60 mg/kg) and were put to death by dislocation of cervical vertebra 12, 24, 48, and 72 hours and 7 days after the injection, respectively. The photoreceptor cell apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and transmission electron microscope. The expression of proliferating cell nuclear antigen (PCNA), vimentin and glial fibrillary acidic protein (GFAP) was detected at different time after injection by immunohistochemical methods. Results The apoptotic index of the retina in the posterior pole was (33. 6±2. 3), (46. 5±5. 7), (20. 1±5. 3), (8. 2±3. 6) and (2. 5±1. 3~//oo at the 12th,24th, 48 th, and 72nd hour and on the 7th day, respectively, after injection. Karyopyknosis was found in most photoreeeptor cells 24 hours after injection. The expression of PCNA was found in internal granularlayer and between internal granular layer and choroid 24 hours after injection, reached the peak after 72 hours, and reduced obviously after 7 days. The positive expression of GFAP and vimentin was found in internal and external granular layer 24 hours after injection, reached the peak after 72 hours, and reducedobviously after 7 days.Conclusion MNU may selectively lead the photoreceptor cell apoptosis and proliferation of Mvller cells. (Chin J Ocul Fundus Dis，2004，20：33-36)