Selective breeding for increased home cage physical activity in collaborative cross and Hsd:ICR mice.

Selective breeding experiments for increased wheel running and open field behavior have identified genetic and neurobiological factors associated with increased voluntary physical activity in mice, but no previous study has directly selected for increased distance traveled in the home cage. Therefore, within-family selection was applied to increase home cage activity as measured by continuous video tracking using two different starting populations, G2:F1 Collaborative Cross (CC) and Hsd:ICR mice. Genetic correlations with distance traveled on running wheels and in the open field were evaluated by mid-parent offspring regression. A significant response to selection was observed in CC but not Hsd:ICR. Wheel running was heritable in both populations but not significantly genetically correlated with home cage activity. Open field was not heritable in either population. We conclude that different genes and neural circuits influence physical activity in the home cage as compared to wheel running or open field. Selective breeding for home cage activity in CC mice warrants further exploration.