The effects of changes in housing on feeding and wheel running.

The experiments explored the effects on feeding when rats were moved between individual and paired housing. In Experiment 1, rats moved to paired housing showed a 3-day suppression in feeding (initially 23%) compared to chronically individual- or pair-housed rats. In Experiment 2, half of the rats from the two control groups of Experiment 1 were moved between individual and paired housing on alternate days. Only the rats moved to paired housing showed a feeding suppression (initially 40%), but the nature of the suppression differed from Experiment 1: it appeared that only one rat of each pair showed a feeding suppression. Experiment 3 examined simultaneous introduction of running wheels and moves to paired housing. The feeding suppression induced by the move to paired housing was more immediate and shorter lived than the wheel-induced suppression. Unlike wheel access, paired housing produced only a temporary suppression of body weight. These experiments suggest that the relatively simple manipulation of moving rats from individual to paired housing results in a temporary stress-induced decrease in feeding.