The Effects of High Dietary Iron and Radiation Exposure on Markers of Oxidative Stress and Immune Status of Rats

Abstract

During space flight astronauts are exposed to increased iron stores and radiation. These can independently cause oxidative damage leading to negative health effects including heart disease, cataracts, and cancer. We investigated the combined effects of high dietary iron (650 mg iron/kg diet vs. 45 mg iron/kg diet for controls) and radiation exposure (0.375 Gy of Cs‐137 every other day for 16 days, a total of 3 Gy) on markers of oxidative stress and immune system variables in Sprague‐Dawley rats (n=8/group). Oxidative stress was affected by both treatments, evidenced by increased liver glutathione peroxidase (P < 0.01) and serum catalase (P < 0.01). Effects of iron intake and radiation on the white blood cell count interacted significantly (P < 0.05), with iron increasing the cell count only in the non‐irradiated group. The T‐cell CD4:CD8 ratio was decreased by radiation (P < 0.0001). When various leukocyte subsets from treated rats were stimulated with mitogens, their cytokine production profiles were altered. Serum iron concentration was negatively correlated with monocyte production of cytokines after LPS stimulation. Both dietary iron and radiation, alone and interactively, contributed to increased oxidative stress and resulted in overall immune system alterations, which could contribute negatively to astronaut health during space flight.Grant Funding Source: Funded by the NASA Human Research Program.