Abstract
Chrysin is a natural flavonoid which is found in bee propolis, honey and various plants, and antidepressant-like effect of chrysin in chronically stressed mice was previously demonstrated by our group. In this work, we investigated the action of chrysin treatment (5 or 20 mg/kg) for 14 days in the depressant-like behavior and in the hippocampal dysfunction induced by olfactory bulbectomy (OB), an animal model of agitated depression. Results demonstrated that OB occasioned a depressant-like behavior in the splash test, open field test and forced swimming test. Chrysin administration, similarly to fluoxetine (positive control), promoted the attenuation of these behavioral modifications. OB also caused the elevation of tumor necrosis factor-α, interferon-γ, interleukin-1β, interleukin-6, kynurenine (KYN) levels and indoleamine-2,3-dioxygenase activity, as well as occasioned the decrease of 5-hydroxytryptamine (5-HT) and brain-derived neurotrophic factor (BDNF) levels and increase KYN/tryptophan and 5-hydroxyindoleacetic acid/5-HT ratio in the hippocampus. Chrysin therapy prevented against all these alterations in the hippocampus. In addition, chrysin treatment (20 mg/kg) resulted in the up-regulation of BDNF levels in the control animals, reinforcing our hypothesis that up-regulation of BDNF synthesis play a key role in the antidepressant action of chrysin. In conclusion, this study showed that chrysin, similarly to fluoxetine, is capable of promoting the attenuation of depressant-like behavior and hippocampal dysfunction resulting from OB in mice. These results reinforced the potential of chrysin for the treatment or supplementary treatment of depression, as well as showed that chrysin is also effective with 14 days of therapy in a model of agitated depression.