Protective effects of morin against depressive-like behavior prompted by chronic unpredictable mild stress in rats: Possible role of inflammasome-related pathways

Depression is a common mental illness that possesses a noteworthy effect on patients' lives. Many theories are recently studied for their plausible involvement in depression pathogenesis, especially oxidative stress and inflammation. Morin (2',3,4',5,7-pentahydroxyflavone), a natural flavonoid, is characterized by its potent anti-inflammatory, and anti-oxidant activities. Accordingly, the aim of the current study was to investigate its potential protective anti-depressant effect in the model of chronic unpredictable mild stress (CUMS) in experimental rats. Moreover, the conceivable neuro-protective mechanisms, especially those related to the inflammasome pathway, were explored. Several, mild, unpredictable stressors were applied for 4 weeks concomitantly with the oral administration of morin (15 and 30 mg/Kg). Morin hydrate supplementations exhibited a significant improvement in the scores of the forced swimming and sucrose preference tests. In addition, it prompted a marked elevation in the ambulation, rearing as well as grooming scores of the open field test. The morin-treated groups showed a great improvement in the biochemical parameters in both the cortex and hippocampus, where it significantly elevated the serotonin, epinephrine, and norepinephrine levels. Also, it significantly increased reduced glutathione levels and decreased malondialdehyde levels. Regarding the inflammasome pathway, morin significantly decreased the tissue levels of tumor necrosis factor-alpha, toll-like receptor-4, interleukin-1beta, NOD-like receptor pyrin domain-containing protein-3, and caspase-1 levels. Morin also significantly decreased the level of the key apoptotic marker, caspase-3. In conclusion, these findings propose that morin might show a promising anti-depressant effect.