FOOD FOR THOUGHT: CIRCADIAN CONTROL OF MOTIVATION AND REWARD BEHAVIOR

ACOSTA J.; BUSSI I.L.; ESQUIVEL M.; GOLOMBEK D.A.; AGOSTINO P.V.

Colonia del Sacramento

Simposio; XV Latin American Symposium on Chronobiology; 2019

In mammals, the circadian system modulates several behavioral and physiological processes, including the response to natural rewards such as food. On the other hand, when food is temporally restricted, animals display an anticipatory food activity (FAA) that is controlled by a food-entrainable oscillator (FEO).In this work, we present evidence that motivation for food reward - assayed through the progressive ratio (PR) schedule - varies dramatically throughout the LD cycle in C57BL/6 mice. We also demonstrate that this variation persists under constant dark (DD) conditions, denoting its endogenous nature. On the contrary, low levels of motivation-related behavior is observed in mice displaying circadian arrythmicity generated by constant light (LL). Furthermore, the daily variation in motivation is also present when using a palatable reward such as chocolate during the motivation task. Taken together, these results indicate that motivation for food reward is regulated in a circadian manner.On the other hand, we also assayed motivation in mice under a restricted feeding (RF) protocol in a 12:12 LD cycle. Mice were allowed to consume food only 3 hours during daytime. Motivation was assayed in two different time points: during FAA (i.e, two hours before food availability) and during the night. Our results show that mice are highly motivated to work for food reward regardless of the time of day. These results suggest that, during FAA, components related to reward pathways might be activated and consecuently generate an increase in motivation bypassing circadian time cues.