title: (56)Fe Irradiation Alters Spine Density and Dendritic Complexity in the Mouse Hippocampus.
abstract: A unique feature of the space radiation environment is the presence of high-energy charged particles, which can be significantly hazardous to space flight crews who are exposed during a mission. Health risks associated with high-LET radiation exposure include cognitive injury. The pathogenesis of this injury is unknown but may involve modifications to dendritic structure and/or alterations in dendritic spine density and morphology. In this study, 24 two-month-old C57BL6/J male mice were either whole-body irradiated with 0.5 Gy (56)Fe (600 MeV/n; n = 12) or sham irradiated (n = 12). Three months postirradiation animals were tested for locomotor activity and habituation. After behavioral testing, animals were euthanized and the brains were flash frozen. Compared to sham-irradiated mice, irradiated mice moved less when first introduced to the environment, although they did recognize the environment when re-exposed to it one day later. Exposure to (56)Fe radiation significantly compromised the dendritic architecture and reduced spine density throughout the hippocampal tri-synaptic network. To our knowledge, these data represents the first reported evidence that high-LET radiation has deleterious effects on mature neurons associated with hippocampal learning and memory.
authors.affiliation: a  Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205;
authors.forename: Antiño R
authors.initials: AR
authors.lastname: Allen
authors.affiliation: c  Departments of Behavioral Neuroscience, Neurology and Radiation Medicine and Division of Neuroscience, ONPRC, Oregon Health and Science University, Portland, Oregon 97239; and.
authors.forename: Jacob
authors.initials: J
authors.lastname: Raber
authors.affiliation: b  Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, California 94110;
authors.forename: Ayanabha
authors.initials: A
authors.lastname: Chakraborti
authors.affiliation: b  Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, California 94110;
authors.forename: Sourabh
authors.initials: S
authors.lastname: Sharma
authors.affiliation: b  Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, California 94110;|d  Department of Radiation Oncology, University of California, San Francisco, California 94110.
authors.forename: John R
authors.initials: JR
authors.lastname: Fike
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology* / Q000528:radiation effects; D049229:Dendritic Spines / Q000528:radiation effects* / Q000648:ultrastructure*; D004307:Dose-Response Relationship, Radiation; D020450:Heavy Ions; D006624:Hippocampus / Q000166:cytology* / Q000502:physiology* / Q000528:radiation effects; D007501:Iron; D007858:Learning / Q000502:physiology* / Q000528:radiation effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011829:Radiation Dosage
chemical_list: D007501:Iron