The biobehavioral and neuroimmune impact of low-dose ionizing radiation

• Published in: Brain, behavior, and immunity Vol. 26; no. 2; pp. 218 - 227
• Main Authors: York, Jason M, Blevins, Neil A, Meling, Daryl D, Peterlin, Molly B, Gridley, Daila S, Cengel, Keith A, Freund, Gregory G
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.02.2012
• Subjects: Acute radiation syndrome (ARS); Allergy and Immunology; 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; Innate immunity; Interleukin 1 Receptor Antagonist Protein - biosynthesis; Interleukin-1 (IL-1); Male; Mice; Motor Activity - drug effects; Nerve Tissue Proteins; Neuroimmunomodulation - radiation effects; Prodromal stage; Psychiatry; Radiation, Ionizing; Restraint, Physical - psychology; Time Factors; Tumor Necrosis Factor-alpha - biosynthesis; Whole-Body Irradiation; Cs; Acute radiation syndrome (ARS); Innate immunity; Co; Interleukin-1 (IL-1); Prodromal stage
• ISSN: 0889-1591; 1090-2139
• DOI: 10.1016/j.bbi.2011.09.006

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.