Stress and radiation responsiveness

Abstract

In contrast to individuals on Earth, astronauts receive much higher doses of ionizing radiation during spaceflight. Besides this, the type of radiation in space is quite different from terrestrial radiation, and consists mainly of high-energy protons and highly charged and energetic particles. It is well known that ionizing radiation can induce both targeted and nontargeted effects in exposed individuals. Resulting damage triggers multiple pathways, including antioxidant recycling, cell cycle checkpoints, and DNA repair. However, when damage is severe, apoptosis, also known as “programmed cell death,” can be induced. The induction of biological effects induced by ionizing radiation depends on the type of radiation, dose, and exposure time. In this context, radiation dosimetry on board spacecraft can be useful to estimate the cumulative equivalent doses to which astronauts are exposed. So far, the precise impact of radiation on the deterioration of the immune system in astronauts is still under investigation. Several ground-based experiments at various radiation facilities have been performed and have contributed to our general knowledge of radiation-induced immune changes. Importantly, radiation also interacts with other spaceflight stressors, such as microgravity, thereby resulting in a joint effect on the immune system. This chapter will provide the latest understanding on the space radiation environment, the appropriate dosimetry, and the complex biological consequences.