Abstract
Purpose: It has been reported that high dose of nitric oxide (NO), which is a high reactive radical, exerts cytotoxic effects, leading to DNA damage, micronucleus (MN) formation, and mutation. Though, low dose of NO may have an opposite effect and protect cell from the death caused by irradiation or ROS stimuli, the mechanism underlying these responses remains unclear. Effect of NO on the radiation-induced micronucleus frequency of RAW264.7 calls was investigated in this study. Methods: Mouse macrophage-like RAW264.7 cells were irradiated with 5Gy gamma-ray in the presence or absence of sodium nitroprusside (SNP), NOC5, NOR4, or S-nitrosoglutathione (GSNO), a chemical NO donor. To determine micronuclei frequency, cells were fixed to a microscope slide and stained with GIMSA and micronuclei were scored under microscopy. Cell cycle was analyzed by flow cytometry. The cellular GSH level was investigated by using conventional method. Results: Micronucleus frequency resulting from 5Gy gamma-rays given at 3~12h after treatment of 0.25mM SNP significantly decreased compared to the number of the value induced by 5Gy gamma ray irradiation alone. Same effect was observed in other NO donors. Conclusions: These results suggest that NO reduces micronucleus frequency induced by 5Gy gamma ray irradiation in RAW264.7 cells.
