Stress and sex influences on food-seeking behaviors.

OBJECTIVE: Stress increases the drive to consume calorically dense preferred foods suggesting an exogenous factor that may induce caloric overconsumption and weight gain. As females show heightened stress sensitivity and present with increased rates of obesity, we hypothesized that stress-induced increases in the motivation for preferred foods may be a sex-specific predisposing factor for weight gain. METHODS AND PROCEDURES: To investigate this hypothesis, we have developed a buried food paradigm that permits the measurement of sex differences and effects of chronic variable stress (CVS) on the latency to uncover and the consumption of a preferred food pellet without the requisite caloric restriction required in traditional operant conditioning tasks.
RESULTS: In our studies, females consistently showed latencies that were twice as fast as males to locate the buried pellet in limited access tests. Interestingly, during stress exposure, male latencies decreased to that of control female levels. Male and female mice showed a significant effect of stress, three- and fourfold, respectively, on increased consumption of the preferred food during testing. DISCUSSION: These results support a basal sex difference in behaviors toward a preferred food, and a possible role of stress sensitivity in the drive and intake of such foods. Sex differences in the role stress plays in these behaviors may provide insight into underlying mechanisms related to an increased obesity risk.