The Biobehavioral and Neuroimmune Impact of Low-Dose Ionizing Radiation

Brain Behav Immun. 2012 Feb;26(2):218-27. doi: 10.1016/j.bbi.2011.09.006. Epub 2011 Sep 21.

Abstract

In the clinical setting, repeated exposures (10-30) to low-doses of ionizing radiation (≤200 cGy), as seen in radiotherapy for cancer, causes fatigue. Almost nothing is known, however, about the fatigue inducing effects of a single exposure to environmental low-dose ionizing radiation that might occur during high-altitude commercial air flight, a nuclear reactor accident or a solar particle event (SPE). To investigate the short-term impact of low-dose ionizing radiation on mouse biobehaviors and neuroimmunity, male CD-1 mice were whole body irradiated with 50 cGy or 200 cGy of gamma or proton radiation. Gamma radiation was found to reduce spontaneous locomotor activity by 35% and 36%, respectively, 6 h post irradiation. In contrast, the motivated behavior of social exploration was un-impacted by gamma radiation. Examination of pro-inflammatory cytokine gene transcripts in the brain demonstrated that gamma radiation increased hippocampal TNF-α expression as early as 4 h post-irradiation. This was coupled to subsequent increases in IL-1RA (8 and 12 h post irradiation) in the cortex and hippocampus and reductions in activity-regulated cytoskeleton-associated protein (Arc) (24 h post irradiation) in the cortex. Finally, restraint stress was a significant modulator of the neuroimmune response to radiation blocking the ability of 200 cGy gamma radiation from impairing locomotor activity and altering the brain-based inflammatory response to irradiation. Taken together, these findings indicate that low-dose ionizing radiation rapidly activates the neuroimmune system potentially causing early onset fatigue-like symptoms in mice.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cerebral Cortex / metabolism
  • Cerebral Cortex / radiation effects
  • Cytoskeletal Proteins
  • Dose-Response Relationship, Radiation
  • Exploratory Behavior / radiation effects
  • Fatigue / chemically induced
  • Gamma Rays
  • Hippocampus / metabolism
  • Hippocampus / radiation effects
  • Interleukin 1 Receptor Antagonist Protein / biosynthesis
  • Male
  • Mice
  • Motor Activity / drug effects
  • Nerve Tissue Proteins
  • Neuroimmunomodulation / radiation effects*
  • Radiation, Ionizing*
  • Restraint, Physical / psychology
  • Time Factors
  • Tumor Necrosis Factor-alpha / biosynthesis
  • Whole-Body Irradiation

Substances

  • Cytoskeletal Proteins
  • Interleukin 1 Receptor Antagonist Protein
  • Nerve Tissue Proteins
  • Tumor Necrosis Factor-alpha
  • activity regulated cytoskeletal-associated protein