Effect of Photoperiod and Lethal Yellow Mutation on Depression-Like Behavior and Expression of Proinflammatory Cytokines in the Hypothalamus in Mice

Abstract

We studied the influence of obesity caused by lethal yellow (A^Y) mutation in the agouti gene, short photoperiod (4/20 h light/darkness), and combination of these factors on depressive-like behavior in the forced swimming test and expression of genes encoding proinflammatory cytokines in the hypothalamus of heterozygous male C57Bl/6-A^Y/a mice and their wild-type littermate controls (C57Bl/6-a/a). It was shown that A^Y mutation as well as short photoperiod increased depressive-like behavior in mice. No effect of the interaction of A^Y mutation and photoperiod on immobility in the forced swimming test was revealed. In wild-type mice, increased depressive-like behavior caused by short photoperiod was accompanied by enhanced expression of Tnf gene. Exposure to short daylight increased the expression of Nos2.