| PURPOSE: To elucidate the mechanisms of photoreceptor apoptosis induced by N-methyl-N-nitrosourea (MNU) in Sprague-Dawley rats.
METHODS: Female Sprague-Dawley rats were intraperitoneally injected with 60 mg/kg MNU at 50 days of age. The characteristics of apoptotic photoreceptor cells were detected by the electron microscopy, TdT-dUTP terminal nick-end labeling (TUNEL) method and flow cytometer. Retinas were then isolated for total RNA preparation followed by microarray-analysis to compare the expression of apoptosis most related genes to controls. Quantitative PCR and Western blot was carried out to confirm altered genes.
RESULTS: MNU-induced photoreceptor damage in SD rats is highly reproducible, and ends within 1 week. In the 212 apoptosis most related genes, the expression of 5 genes was up-regulated 12hrs after administration of MNU on SD rats, including the members of FADD/Caspase8 pathway and other mechanisms. These changes were also confirmed by real-time quantitative (Taqman) PCR and Western blot analysis.
CONCLUSIONS: Our present datas suggested that the administration of MNU to SD rats induced photoreceptor apoptosis is related with activation of FADD/Caspase8 pathway and was an useful model for evaluation of therapeutic strategies for human RP.
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