Differential effects of chronic social stress and fluoxetine on meal patterns in mice

Both chronic stress and antidepressant medications have been associated with changes in body weight. In the current study, we investigate mechanisms by which stress and antidepressants interact to affect meal patterns. A group of mice was subjected to the chronic social defeat stress model of major depression followed by fluoxetine treatment and was subsequently analyzed for food intake using metabolic cages. We report that chronic social defeat stress increases food intake by specifically increasing meal size, an effect that is reversed by fluoxetine treatment. In an attempt to gain mechanistic insight into changes in meal patterning induced by stress and fluoxetine, fasting serum samples were collected every 4 h over a 24-h period, and acyl-ghrelin, leptin, and corticosterone levels were measured. Chronic stress induces a peak in acyl-ghrelin levels just prior to the onset of the dark phase, which is shifted in mice treated with fluoxetine. Taken together, these results indicate that stress increases food intake by decreasing satiation, and that fluoxetine can reverse stress-induced changes in meal patterns.

► Chronic social defeat stress increases meal size in mice.
► Fluoxetine reverses stress-induced increase in meal size.
► Fluoxetine shifts stress-induced increase in plasma acyl-ghrelin levels.
► Intrameal satiation is regulated in a model of depression and by an antidepressant.