In Vivo Mechanisms of Radioadaptive Response

Abstract

Background & Objectives: Radioadaptive response (RAR) describes a phenomenon in which small priming doses of ionizing radiation (IR) reduce detrimental effects of subsequent higher doses. Since IR-induced carcinogenesis is a main concern in the low-dose radiation risk assessmen, the aim of this study was to investigate the RAR with the end points of carcinogenesis and the related genomic damages and evaluation of the effective in-vivo mechanisms in this phenomenon. Materials & Methods: The present review article was performed by using the research and review articles indexed in Pubmed, Google scholar, Science direct. In this review article, some resent studies related to RAR with end points of carcinogenesis in different species of mice and human lymphocytes has been investigated. Additionally, in the present review article, the role of important in vivo mechanisms involved in adaptive response, namely DNA repair, bystander effect and endocrine system hormones such as glucocorticoids has been investigated. Results: These studies, often revealed efficient induction of RAR by chronic or repeated low-dose priming irradiation. Conclusion: Current radiation protection regulations do not include RAR because of the large variability in expression among individuals and uncertainties of the mechanism. However, in the future, RAR should be regarded as an indispensable factor for estimation and control of individual IR sensitivity.

Keywords

• adaptive response
• low-dose radiation
• ionizing radiation
• dna repair
• bystander effect
• cancer