Blunted food conditioned place preference-like behavior in adolescent-stressed male hamsters

Social stress during adolescence results in long lasting weight gain, obesity, and enhanced food hoarding behavior in hamsters. We wanted to determine whether stress also enhanced conditioned place preference-like behavior (CPP-like) for food reward, as would be expected from studies with substances like cocaine. Our experimental animals were exposed daily to aggressive adults for two weeks in early puberty, while also trained to explore a V-shaped maze containing a food reward at one end. They were tested for CPP-like behavior on the last day of social stress. Our results showed that while stress enhanced weight gain, food intake, food efficiency, and body fat, it caused a reduction of Place Preference as compared to controls. In fact, the correlated relationship between Place Preference and body fat was inverted by stress exposure: while it was positively correlated in controls, it was mildly negatively correlated in stressed hamsters. These unexpected data illustrate the extent of adaptive behavior in foraging animals once a resource has become untrustworthy.