The effect of chronic stress on motivation in mice: a novel approach

Abstract

Chronic stress is a well-established contributor to mental health disorders, such as depression, which often manifests with motivational deficits as a symptom. While previous animal studies have suggested that chronic stress causes decreases in motivation, methodological concerns of confounding factors like food deprivation and inactivity made us question these conclusions. Here, we employed a novel approach using the Feeding Experimental Devices 3 (FED3) box to measure effort-based motivation in mice within their home cages and without food deprivation, minimizing additional stressors. We investigated the effects of chronic social defeat (CSD) and corticosterone (CORT) administration on motivation. Our results indicate a short-term reduction in motivation without long-term effects that was observed in previous research. Further research will need to be done to determine if this might be due to the duration of the chronic stress treatment, or the absence of continuous confounding stressors. Additionally, the lack of correlation between plasma corticosterone levels and deficit in motivation suggests a complex mechanism in which chronic stress induces motivational deficits.