Assessment of the bystander effect of low dose gamma radiation on rats’ bone marrow

. Radiation-induced bystander effect (RIBE), is well verified in radiation biology field. Vast bulk of these effects are defined in cell culture systems, while in vivo authentication and evaluation of biological consequences still vague. We aimed to mechanistically interrogate RIBE responses thus this study was conducted. Accordingly, Albino rats’ right femurs were exposed to 0.25, 0.45 and 0.75 Gу γ-radiation. Rats were euthanized 1 day and ten days post irradiation, total antioxidant capacity and mRNA expression levels of Stromal Derived Growth Factor (SDF-1) were evaluated in bone marrow. Blood micronucleated polychromatic erythrocytes (fMNPCEs) and femoral muscle’s lipid peroxidation (LPO) were measurable. Femoral muscle’s LPO, total antioxidant capacity and mRNA genes expression levels were significantly increased in both left and right femur at 0.45 and 0.75 Gy 24 h post irradiation and retained near control levels 10 days post irradiation. fMNPCEs became significantly higher 24 h post irradiation and showed a non-significant difference at all doses ten days post irradiation. In conclusion, the increase of LPO in femur muscle, with elevation in SDF-1 mRNA expression levels in bone marrow, and total antioxidant capacity in non-irradiated left femurs indicate that a bystander effect exists.