Behavioural consequences of an 8 Gy total body irradiation in mice: regulation by interleukin-4.

The effects of an 8 Gy gamma total body irradiation (TBI) on exploration and locomotion activities as well as temperature were studied in C57BL6/J mice. Survival, body weight, and blood cell counts were also assessed in irradiated mice treated with placebo or interleukin (IL)-4. The efficacy of IL-4 treatment on improvement in exploration activity was evaluated. The study was carried out from 3 h to 30 days following exposure. Our results showed a biphasic response to irradiation concerning the exploration activity of mice. Irradiated mice had reduced activity as early as 3 h after exposure, with recovery of activity within 24 h. The exploration activity again decreased 4 days after irradiation and the recovery occurred slowly after day 17. IL-4 ameliorated the exploration status in mice in both phases. The locomotion activity was studied using a telemetry apparatus. A similar pattern to that of the exploration data was observed, with a minimal activity observed between days 13 and 17. A radiation-induced hypothermia was also noticed over the same time period.