抄録
The differential radiation environment encountered in space may cause deleterious effects in humans, and these effects are of special concern for prolonged space missions beyond the protective terrestrial magnetosphere. Furthermore, exposure to space radiation in a microgravity environment may induce a synergistic effect leading to compounded detrimental outcomes, and thus have a major impact on the risk assessment for space travel. Due to the fact that many cellular signaling pathways activated by physiological stresses and DNA damage overlap, interactions between these activated pathways could potentially alter the radiosensitivity of crewmembers on space missions. Ideally, investigations to elucidate the synergistic effects of space environmental factors and radiation require exposure of samples to a controlled radiation source in the microgravity environment. Over the last several decades, a number of flight experiments have been conducted to address the specific question of a possible synergism between radiation exposure and microgravity environment, but the issue remains unresolved due to the limitations of flight experiments and other factors. We will review the studies that addressed this specific question and discuss the limitations of flight experiments. Our data on a Space Shuttle astronaut will also be presented.
