Diphenyl diselenide supplemented diet reduces depressive-like behavior in hypothyroid female rats

Hypothyroidism has been associated to psychiatric disorder development and tissue oxidative damage. In this study, we evaluated the effect of diphenyl diselenide supplementation on depressive-like behavior triggered by methimazole exposure in female rats. Additionally, thiobarbituric acid reactive substances (TBARS), reactive oxygen species (ROS) and non-protein thiol (NP-SH) levels were analyzed in cerebral cortex, hippocampus and striatum structures of rats. Monoamine oxidase (MAO) activity was evaluated in total brain. Firstly, female rats received methimazole (MTZ) 20mg/100ml in the drinking water for 30days and were evaluated in open-field and forced swimming tests (FST). In this set of experiments, the rats exposed to MTZ presented a depressive-like behavior, which was evidenced by a significant increase in the immobility time when compared to control group. Thereafter, MTZ-induced hypothyroid rats received either a standard or a diet containing 5ppm of diphenyl diselenide, and then they were evaluated monthly in open-field and FST tests during 3months. No alteration on the locomotor performance was observed among the groups. The depressive-like behavior of hypothyroid rats was blunted by diphenyl diselenide supplementation during all experimental periods. The levels of thyroid hormones remained low in MTZ exposed groups until the end of experimental period. The MTZ group had an increase in TBARS and ROS levels that were restored by diphenyl diselenide supplementation. NP-SH content of cerebral structures was not modified by MTZ exposure and/or diphenyl diselenide supplementation. Diphenyl diselenide supplementation restored the MAO B activity that was decreased in MTZ group. In summary, our results show that hypothyroidism induced by MTZ methimazole triggers a depressive-like behavior in female rats and that dietary diphenyl diselenide was able to reduce this effect.