Effects of Low-dose Gamma Radiation on Expression of Apoptotic Genes in Rat Peripheral Blood Lymphocyte

Background: Exposure to high-dose ionizing radiation is known as a human carcinogen factor, but our information about the effects of low-dose ionizing radiation such as occupational exposures is limited. The main concern of scientific community is biological consequences due to low-dose radiations. Objective: This study aims to evaluate the effects of low-dose γ-radiation on expression changes of apoptotic genes (bax and bcl-۲) in the rat peripheral blood lymphocytes.Material and Methods: In this experimental study, ۴۲ adult male rats were classified into ۶ groups, which was exposed to various doses values ranged from ۲۰ mGy to ۱۰۰۰ mGy by γ-rays from a Co-۶۰ source. Blood samples were provided for analysis of gene expression ۲۴ h after gamma radiation by relative quantitative Reverse Transcription - Polymerase Chain Reaction (RT-PCR). Radiation sensitivity of rat lymphocytes was measured by the bax/bcl-۲ ratio as a predictive marker for radio-sensitivity. Results: The results of this study showed that low dose of gamma radiation can induce down-regulation of bax in rat peripheral blood lymphocytes. Despite other mechanisms of cellular radio-protection, changes in expression of these apoptotic genes can be the primary pathway in responses of the lymphocytes radio-protection to the exposure. Our study revealed a significant decrease in the bax/bcl-۲ ratio at ۵۰ mGy dose compare to control and the other irradiated groups (p < ۰.۰۵). Conclusion: These results suggest that changes in the bax/bcl-۲ ratio especially in radiation workers, as a key factor in apoptosis, can be considered as a biological marker in low-dose gamma radiation.

Keywords:

Gamma Radiation , Real-Time Polymerase Chain Reaction , Bcl-۲-Associated X Protein , Genes , P۵۳ , Radiation Sensitivity