title: Effect of behavioral testing on spine density of basal dendrites in the CA1 region of the hippocampus modulated by (56)Fe irradiation.
abstract: A unique feature of the space radiation environment is the presence of high-energy charged particles, including (56)Fe ions, which can present a significant hazard to space flight crews during and following a mission. (56)Fe irradiation-induced cognitive changes often involve alterations in hippocampal function. These alterations might involve changes in spine morphology and density. In addition to irradiation, performing a cognitive task can also affect spine morphology. Therefore, it is often hard to determine whether changes in spine morphology and density are due to an environmental challenge or group differences in performance on cognitive tests. In this study, we tested the hypothesis that the ability of exploratory behavior to increase specific measures of hippocampal spine morphology and density is affected by (56)Fe irradiation. In sham-irradiated mice, exploratory behavior increased basal spine density in the CA1 region of the hippocampus and the enclosed blade of the dentate gyrus. These effects were not seen in irradiated mice. In addition, following exploratory behavior, there was a trend toward a decrease in the percent stubby spines on apical dendrites in the CA3 region of the hippocampus in (56)Fe-irradiated, but not sham-irradiated, mice. Other hippocampal regions and spine measures affected by (56)Fe irradiation showed comparable radiation effects in behaviorally naïve and cognitively tested mice. Thus, the ability of exploratory behavior to alter spine density and morphology in specific hippocampal regions is affected by (56)Fe irradiation.
authors.affiliation: Department of Behavioral Neuroscience, ONPRC, Oregon Health and Science University, Portland, OR 97239, United States; Departments of Neurology, Radiation Medicine and Division of Neuroscience, ONPRC, Oregon Health and Science University, Portland, OR 97239, United States. Electronic address: raberj@ohsu.edu.
authors.forename: Jacob
authors.initials: J
authors.lastname: Raber
authors.affiliation: Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States.
authors.forename: Antiño R
authors.initials: AR
authors.lastname: Allen
authors.affiliation: Department of Behavioral Neuroscience, ONPRC, Oregon Health and Science University, Portland, OR 97239, United States.
authors.forename: Sydney
authors.initials: S
authors.lastname: Weber
authors.affiliation: Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, CA 94110, United States; The Brain Research Institute at Monash Sunway, Selangor Darul Ehsan, Malaysia.
authors.forename: Ayanabha
authors.initials: A
authors.lastname: Chakraborti
authors.affiliation: Departments of Neurology, Radiation Medicine and Division of Neuroscience, ONPRC, Oregon Health and Science University, Portland, OR 97239, United States.
authors.forename: Sourabh
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Departments of Neurology, Radiation Medicine and Division of Neuroscience, ONPRC, Oregon Health and Science University, Portland, OR 97239, United States; Department of Radiation Oncology, University of California, San Francisco, CA 94110, United States.
authors.forename: John R
authors.initials: JR
authors.lastname: Fike
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000528:radiation effects* / Q000648:ultrastructure*; D003071:Cognition / Q000528:radiation effects; D049229:Dendritic Spines / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D060733:Electromagnetic Radiation; D005106:Exploratory Behavior / Q000528:radiation effects*; D005296:Ferrous Compounds / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011846:Radio Waves; D016622:Silver Staining
chemical_list: D005296:Ferrous Compounds
keywords: Exploratory behavior; Hippocampus; Irradiation; Mouse; Spine density