Adaptive response to ionizing radiation and the role of vitamin B12 in amelioration radiation protection standards

This work was carried out to study the protective role of vitamin B12 on the induced cytotoxicity and genotoxicity of ionizing radiation on male mice, as assessed using micronucleus technique and by analyzing the morphological abnormalities of spermatozoa.Male mice were injected intramuscularly with vitamin B12, at a dose of 0.8 mg/kg body weight, 1 h prior to a whole body exposure to 2 Gy gamma irradiation, followed by 2 Gy as a challenged dose. Animals were sacrificed 6, 24, and 72 h post-irradiation. The frequency of micronucleated polychromatic erythrocytes (PCEs) and normochromatic erythrocytes (NCEs); the ratio of PCEs/NCEs; and the mitotic index (MI) of bone marrow cells and sperm, head, and tail abnormalities were evaluated. Administration of vitamin B12 pre-irradiation resulted in a significant inhibition in the frequency of radiation-induced MNPCE and MNNCE as well as in the ratio of PCEs/NCEs and MI of bone marrow cells and a significant amelioration in sperm head and tail abnormalities.The results suggested that vitamin B12 in a dose of 0.8 mg/kg body weight plays a protective role when administered prior to irradiation.