Short-term γ-ray Irradiation with Hyperoxia Induces Lifespan Extension in Caenorhabditis elegans

Abstract

Human astronauts follow a fixed prebreathing protocol consisting of 100% hyperoxia exposure repeated several times weekly before conducting the extravehicular activities in interplanetary space. However, despite astronaut exposure to both space radiation and hyperoxia, which have different biological effects on cells, the combinatorial effects on aging and longevity is unknown. Here, we evaluated the interactive effects on aging using Caenorhabditis elegans exposed to short-term ⁶⁰Co γ-ray irradiation and hyperoxia. Thus, combined treatment extended the lifespan by approximately 10-15% in wild-type worms compared with irradiation only. Moreover, we found that the interaction induced not only the expression of antioxidant genes via insulin/IGF-1 signaling and the reduction of mitochondrial ROS, but also the activation of DNA damage repair system and sirtuin homologue genes during aging. Despite short-term irradiation of low linear energy transfer (LET) radiation such as γ-ray inducing transiently transcriptional inactivation of most genes, the levels of genes expression were recovered under hyperoxia during aging, at least partially. These findings in the C. elegans, showing that genetic transcriptional and mitochondrial dynamics depend on the interaction of low LET radiation with hyperoxia to consequently boost longevity, suggest some intracellular molecular targets to protect astronauts in space.