Quercetin reverses chronic unpredictable mild stress-induced depression and behavioural abnormalities in Swiss mice

Abstract

Context: Chronic stress is a known trigger of inflammatory responses and oxidative stress that underpin the pathogenesis of depression. Although quercetin is a flavonoid widely known for its anti-inflammatory, antioxidant and adaptogenic effects, its potential against stress-related depression has not been fully studied.

Objective: This study aimed to investigate the effect of quercetin on chronic unpredictable mild stress (CUMS)-induced depression in mice.

Materials and Methods: Swiss mice were divided into four groups of seven animals each. Group 1 received vehicle, group 2 received vehicle, and groups 3 and 4 received quercetin (12.5 mg/kg and 25 mg/kg, respectively). All animals except those in group 1 were exposed daily to unpredictable stressors for twenty-one days. Behavioural studies were carried out twenty-four hours after the last treatment (day 22). The mice were anaesthetized and sacrificed, and their brain samples were removed for histology and biochemical assays of proinflammatory cytokines. The data was analysed using one way analysis of variance (ANOVA) and a post hoc test. The level of significance was set at p<0.05.

Results: Compared with vehicle treatment, CUMS induced behavioural dysfunction by significantly decreasing grooming activity in the sucrose splash test and increasing immobility time in the forced swim test (FST) and tail suspension test (TST). CUMS also increased proinflammatory cytokine levels in the brain and reduced the arborization of dendritic cells. All these parameters were significantly reversed (p<0.05) by quercetin (12.5 mg/kg and 25 mg/kg).

Conclusion: Our results showed that quercetin significantly attenuated depressive symptoms in CUMS-exposed mice and exerted neuroprotective effects by markedly inhibiting the reduction in the arborization of dendritic cells in the brain. This neuroprotective effect may be due to the inhibition of neuroinflammatory cytokines.