Abstract: Objective To observe the changes of nuclear factor-κappa B(NF-κB)in the course of N-methyl-N-nitrosourea(MNU)-induced apoptosis of rat retinal photoreceptor cells and investigate the mechanism of MNU-induced retinal damage.Methods A single intraperitoneal injection of 60 mg/kg MNU was given to 50-day-old female rats,which were sacrificed at different intervals after MNU treatment.The retinal damage was examined with optical microscopy and photoreceptor cell apoptosis detected by TUNEL assay.Western blotting was performed to analyze the changes in NF-κB.Results Pyknosis of the photoreceptor cell nuclei and disorientation of the outer segment of the photoreceptor layer was observed 24 h after MNU treatment,and the outer nuclear layer and photoreceptor layer were almost completely lost on day 7.Photoreceptor cell apoptosis peaked at 24 h,and in the apoptotic cascade,NF-κB p65 protein was only detected 12 and 24 h after MNU treatment,whereas the amount of IκBα,in contrast,markedly increased in the cytoplasm as well as in the nuclei.Conclusion MNU-induced retinal damage might be mediated through the signaling pathway of NF-κB/IκBα.