Protection of mice against X-ray injuries by the post-irradiation administration of guanosine and inosine

Purpose: To examine the radioprotective action of guanosine (Guo) and inosine (Ino) administered to mice after irradiation with X-rays.Materials and methods: Survival of mice exposed to lethal and sublethal doses of X-rays was studied. Peripheral blood cells were counted using a light microscope. The damage to bone marrow cells was assessed by micronucleus (MN) test. Damage and repair of DNA in blood leukocytes were estimated using the comet assay.Results: Mice injected intraperitoneally (i.p.) with Guo or Ino (∼30 μg g−1, i.e., ∼0.6 mg per 20-g mouse) 15 min after acute whole-body irradiation with 7 Gy recovered from X-ray injury. On the 30th day after irradiation, 50 and 40% of mice injected with Guo and Ino, respectively, remained alive. The dose reduction factor (DRF) was 1.23 for Guo and 1.15 for Ino. The protective effect gradually decreased as the time interval between the irradiation and injection was increased to 3, 5, 8 h. Guo and Ino facilitated the restoration of peripheral blood cell counts. ...