Yang Jin-nan, Luo Lin, Lin Shao-chun, Chen Jin-mao, Li Dai, Hu Shi-xing
Department of Pharmacy, Xinxiang Medical College of Henan Province, Xinxiang 453003, China.
Chin Med J (Engl). 2005 Jul 5;118(13):1081-6.
Previous studies have showed that photooxidative stress can lead to down-modulation of nuclear factor-kappa B (NF-kappaB) activity causing apoptosis of cultured photoreceptor cells. This study aimed at investigating whether NF-kappaB was involved in photoreceptor cells apoptosis induced by N-methyl-N-nitrosourea (MNU) in rats.
A single intraperitoneal injection of 60 mg/kg MNU was given to 50-day-old female rats. At different intervals after MNU treatment, the animals were sacrificed. Retinal damage was examined by a light microscope. The apoptotic index of the photoreceptor cells was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL). NF-kappaB was analysed by Western blot and Transcriptin Factor Assay Kits.
The pyknosis of the photoreceptor nuclei and the disorientation of the outer segment of the photoreceptor layer was seen after MNU treatment for 24 hours. The outer nuclear layer and photoreceptor layer were almost completely lost at 7 days. Photoreceptor cells apoptosis reached the peaked value at 24 hours. In apoptotic cascade, the protein levels of NF-kappaB p65 were only detected after MNU treatment for 12 and 24 hours in the nucleus. Conversely, the amounts of IkappaBalpha were markedly increased in the cytoplasm as well as in the nucleus. The activity of NF-kappaB p65 in the nucleus was down-modulated in the end.
MNU-induced photoreceptor cell destruction was attributed to the apoptotic process by down-regulating the activation of NF-kappaB p65.
先前的研究表明，光氧化应激可导致核因子-κB（NF-κB）活性下调，从而引起培养的光感受器细胞凋亡。本研究旨在探讨NF-κB是否参与N-甲基-N-亚硝基脲（MNU）诱导的大鼠光感受器细胞凋亡。
对50日龄雌性大鼠腹腔注射60mg/kg MNU。在MNU处理后的不同时间点处死动物。通过光学显微镜检查视网膜损伤情况。采用末端脱氧核苷酸转移酶介导的dUTP-生物素缺口末端标记法（TUNEL）检测光感受器细胞的凋亡指数。通过蛋白质免疫印迹法和转录因子检测试剂盒分析NF-κB。
MNU处理24小时后可见光感受器细胞核固缩，光感受器层外节排列紊乱。7天时外核层和光感受器层几乎完全消失。光感受器细胞凋亡在24小时达到峰值。在凋亡级联反应中，仅在MNU处理12小时和24小时后在细胞核中检测到NF-κB p65的蛋白水平。相反，IκBα在细胞质和细胞核中的含量均显著增加。最终细胞核中NF-κB p65的活性下调。
MNU诱导的光感受器细胞破坏归因于通过下调NF-κB p65的激活而导致的凋亡过程。
