title: Spatial Memory Performance of Socially Mature Wistar Rats is Impaired after Exposure to Low (5 cGy) Doses of 1 GeV/n48Ti Particles.
abstract: Prolonged deep space missions to planets and asteroids will expose astronauts to galactic cosmic radiation (GCR), a mixture of low-LET ionizing radiations, high-energy protons and high-Z and energy (HZE) particles. Ground-based experiments are used to determine whether this radiation environment will have an effect on the long-term health of astronauts and their ability to complete various tasks during their mission. Emerging data suggest that mission-relevant HZE doses impair several hippocampus-dependent neurocognitive processes in rodents, but that there is substantial interindividual variation in the severity of neurocognitive impairment, ranging from no observable effects to severe impairment. While the majority of studies have established the effect that the most abundant HZE species (56Fe) has on neurocognition, some studies suggest that the lighter48Ti HZE particles may be equally, if not more, potent at impairing neurocognition. In this study, we assessed the effect that exposure to 5-20 cGy 1 GeV/n48Ti had on the spatial memory performance of socially mature male Wistar rats. Acute exposures to mission-relevant doses (≤5 cGy) of 1 GeV/n48Ti significantly (P < 0.05) reduced the mean spatial memory performance of the rats at three months after exposure, and significantly (P < 0.015) increased the percentage of rats that have severe (Z score ≥ 2) impairment, i.e., poor performers. Collectively, these data further support the notion that the LET dependency of neurocognitive impairment may differ from that of cell killing.
authors.affiliation: Department of aRadiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507.|b   Department of Microbiology, Eastern Virginia Medical School, Norfolk, Virginia 23507.|c   Leroy T. Canoles Jr. Cancer Center, Eastern Virginia Medical School, Norfolk, Virginia 23507.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Britten
authors.affiliation: Department of aRadiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507.
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Jewell
authors.affiliation: Department of aRadiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507.
authors.forename: Vania D
authors.initials: VD
authors.lastname: Duncan
authors.affiliation: Department of aRadiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507.
authors.forename: Leslie K
authors.initials: LK
authors.lastname: Davis
authors.affiliation: Department of aRadiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507.
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Hadley
authors.affiliation: d   Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wyrobek
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D007501:Iron / Q000009:adverse effects; D008297:Male; D018782:Maze Learning / Q000528:radiation effects; D051381:Rats; D017208:Rats, Wistar; D012919:Social Behavior; D065852:Spatial Memory / Q000528:radiation effects*; D014025:Titanium / Q000009:adverse effects*
chemical_list: D014025:Titanium; D007501:Iron