title: Sex- and dose-dependent effects of calcium ion irradiation on behavioral performance of B6D2F1 mice during contextual fear conditioning training.
abstract: The space radiation environment includes energetic charged particles that may impact behavioral and cognitive performance. The relationship between the dose and the ionization density of the various types of charged particles (expressed as linear energy transfer or LET), and cognitive performance is complex. In our earlier work, whole body exposure to (28)Si ions (263 MeV/n, LET=78keV/μm; 1.6 Gy) affected contextual fear memory in C57BL/6J × DBA2/J F1 (B6D2F1) mice three months following irradiation but this was not the case following exposure to (48)Ti ions (1 GeV/n, LET=107keV/μm; 0.2 or 0.4 Gy). As an increased understanding of the impact of charged particle exposures is critical for assessment of risk to the CNS of astronauts during and following missions, in this study we used (40)Ca ion beams (942 MeV/n, LET=90keV/μm) to determine the behavioral and cognitive effects for the LET region between that of Si ions and Ti ions. (40)Ca ion exposure reduced baseline activity in a novel environment in a dose-dependent manner, which suggests reduced motivation to explore and/or a diminished level of curiosity in a novel environment. In addition, exposure to (40)Ca ions had sex-dependent effects on response to shock. (40)Ca ion irradiation reduced the response to shock in female, but not male, mice. In contrast, (40)Ca ion irradiation did not affect fear learning, memory, or extinction of fear memory for either gender at the doses employed in this study. Thus (40)Ca ion irradiation affected behavioral, but not cognitive, performance. The effects of (40)Ca ion irradiation on behavioral performance are relevant, as a combination of novelty and aversive environmental stimuli is pertinent to conditions experienced by astronauts during and following space missions.
authors.affiliation: Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR 97239, USA; Departments of Neurology and Radiation Medicine, Division of Neuroscience ONPRC, Oregon Health and Science University, Portland, OR 97239, USA. Electronic address: raberj@ohsu.edu.
authors.forename: Jacob
authors.initials: J
authors.lastname: Raber
authors.affiliation: Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR 97239, USA.
authors.forename: Sydney J
authors.initials: SJ
authors.lastname: Weber
authors.affiliation: Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Kronenberg
authors.affiliation: Oregon Institute of Occupational Health Sciences and Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR 97239, USA.
authors.forename: Mitchell S
authors.initials: MS
authors.lastname: Turker
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology* / Q000528:radiation effects; D002132:Calcium Radioisotopes / Q000009:adverse effects*; D003213:Conditioning, Psychological / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005239:Fear / Q000523:psychology* / Q000528:radiation effects; D005260:Female; D008297:Male; D008568:Memory / Q000502:physiology* / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D011839:Radiation, Ionizing; D012737:Sex Factors
chemical_list: D002132:Calcium Radioisotopes
keywords: Contextual; Extinction; Fear memory; Hippocampus; Irradiation