The effects of learning on the eating responses of rats exposed to stress

Abstract

Literature examining the relationship between stress and eating behaviour reveals that while both decreased and increased eating are observed in response to stress, it is unclear what factors determine whether an individual will typically decrease or increase eating during stress. The present study sought to explore whether decreased/increased eating in response to future stressors, could be elicited by prior associations between decreased/increased eating and the presentation of a stressor, through operant conditioning. The “Conditioned Non-Eaters” (CNE) group received punishment training while the “Conditioned Eaters” (CE) group received negative reinforcement training in response to a noise stressor, and the Control group received no operant training. Conditioning trials were followed by a series of five tests exposing subjects to no stress, the noise stimulus, threat of shock, restraint, and a tail-pinch. Results indicate that group differences in eating were observed during exposure to the noise stimulus following training, but not in the absence of stress, and consistent group differences to the noise stress were further observed during exposure to novel stressors. These findings suggest that past operant associations between eating and a specific stressor can generalize to other stressors, influencing individuals to respond to stress exposure in a way that has be reinforced in the past.