即早基因在N-甲基-N-亚硝脲诱导SD大鼠视网膜变性中的表达

目的研究N-甲基-N-亚硝脲(N-m ethyl-N-n itrosourea,MNU)对SD大鼠视网膜毒性的分子机制。方法于♀SD大鼠出生后50 d,一次腹腔注射(ip)MNU 60 mg.kg-1。在MNU处理不同时间后,处死大鼠,取眼球。进行组织学检查;TUNEL试剂盒检测光感受器细胞凋亡;RT-PCR法检测基因c-jun和c-fos的表达。结果MNU作用24 h后,视网膜光感受器外节部定向紊乱;7 d后,外颗粒层和光感受层几乎完全消失。MNU作用12 h后,光感受器细胞开始发生凋亡,24 h达高峰。MNU可时间依赖性地上调即早基因的表达。结论MNU对视网膜的毒性作用是通过增加基因c-jun和c-fos的表达,从而诱导光感受器细胞发生凋亡。

Expression of immediate early gene following N-methyl-N-nitrosourea-induced retinal degeneration in SD rats

Aim To study the molecular mechanism of retinal toxicity induced by N-methyl-N-nitrosourea (MNU) in SD rats. Methods A single intraperitoneal injection of 60 mg·kg~(-1) MNU was given to 50-day-old female SD rats. After MNU treatment for different times, the rats were sacrificed and both eyes were enucleated immediately and processed for histological examination. The apoptotic index of photoreceptor cells was calculated by TUNEL labeling and the expression of c-jun and c-fos genes was detected by RT-PCR technique. Results After the application of MNU for 24 h,the disorientation of photoreceptor outer segments was seen. The outer nuclear layer and photoreceptor layer were almost completely lost at 7 d. Apoptosis had already started at 12 h post-MNU and peaked at 24 h. MNU time-dependently up-regulated the expression of c-jun and c-fos genes. Conclusion MNU has a toxic effect on retina by up-modulating expression of c-jun and c-fos genes to promote photorecptor cells apoptosis.