Sex-dependent effects of 56Fe irradiation on contextual fear conditioning in C57BL/6J mice.

Effects of irradiation on hippocampal function have been mostly studied in male rodents and relatively little is known about potential effects of irradiation on hippocampal function in female rodents. Moreover, although the long-term effects of clinical radiation on cognitive function have been well established, the effects of other forms of irradiation, such as high charged, high energy radiation (HZE particles) that astronauts encounter during space missions have not been well characterized. In this study we compared the effects of (56)Fe irradiation on fear conditioning in C57BL/6J female and male mice. Hippocampus-dependent contextual fear conditioning was impaired in female mice but improved in male mice following (56)Fe irradiation. Such impairment was not seen for hippocampus-independent cued fear conditioning. Thus, the effects of (56)Fe irradiation on hippocampus-dependent contextual fear conditioning are critically modulated by sex. Copyright 2009 Wiley-Liss, Inc.