28Silicon Irradiation Impairs Contextual Fear Memory in B6D2F1 Mice

The space radiation environment consists of multiple species of charged particles, including Si-28, Ti-48 and protons that may impact cognition, but their damaging effects have been poorly defined. In mouse studies, C57Bl6/J homozygous wild-type mice and genetic mutant mice on a C57Bl6/J background have typically been used for assessing effects of space radiation on cognition. In contrast, little is known about the radiation response of mice on a heterozygous background. Therefore, in the current study we tested the effects of Si-28, Ti-48 and proton radiation on hippocampus-dependent contextual fear memory and hippocampus-independent cued fear memory in C57Bl6/J x DBA2/J F1 (B6D2F1) mice three months after irradiation. Contextual fear memory was impaired at a 1.6 Gy dose of Si-28 radiation, but not cued fear memory. Ti-48 or proton irradiation did not affect either type of memory. Based on earlier space radiation cognitive data in C57Bl6/J mice, these data highlight the importance of including different genetic backgrounds in studies aimed at assessing cognitive changes after exposure to space radiation. (C) 2015 by Radiation Research Society