Balancing Energy Demands with the Potential for Threat in the Environment
behavioural defense profiles , food restriction
In their natural environment animals must balance their safety requirements (i.e., avoiding predation) with their need to satisfy their energy demands (i.e., securing food). How the brain integrates these competing demands to promote adaptive responding is not well understood. The current study examined the effects of chronic food restriction on rats' behavioural defense profiles in two animal models of anxiety; the shock-probe burying and elevated plus-maze tests. In agreement with previous research, food restriction dramatically increased rats' open-arm exploration in the plus-maze. By contrast, food restriction did not alter the duration of time rats spent burying an electrified probe in the shock-probe burying test. Furthermore, food restricted rats displayed increases in risk assessment behaviour in both tests. Animals’ behaviour in both animal models of anxiety does not suggest a food-restriction induced reduction in anxiety. Alternatively, the results suggest that rats' willingness to explore normally avoided open arenas is sensitive to their current energy demands. In particular, it appears that under conditions of food scarcity rodents adapt their defensive profiles in order to meet both safety needs and satisfy energy demands. Further, the dramatic shift in open-arm exploration displayed by food-restricted animals seems to involve activation (as indexed by cFos) of brain regions previously implicated in feeding behaviour and normal open arm avoidance. Notably, an interaction effect of feeding and testing was observed in the anterior basolateral amygdala. This nucleus may be involved in integrating the competing demands of safety and energy requirements.