Depressive disorder is a kind of affective disturbance disease. Emerging evidence has suggested that inflammation may contribute to the pathologic process of depressive disorder. Senegenin (SEN), a major bioactive constituent in Polygala tenuifolia Willd, has much bioactivity including anti-inflammatory and neuroprotection effects. However, the mechanism of its anti-depressant effect in mice remains unknown. This study aimed to explore the anti-depressant effects of SEN on behavioral changes and inflammatory responses in mice induced by chronic un-predictable mild stress (CUMS). SEN treatment remarkably ameliorated CUMS-induced behavioral abnormalities, such as improving locomotor activity, decreasing immobility time in Tail suspension test (TST) and Forced swimming test (FST), and increasing sucrose intake in Sucrose preference test (SPT). Additionally, SEN improve protein levels of Brain-derived neurotrophic factor (BDNF) and Neurotrophin-3 (NT-3) expression.
In response to stress, p65 was activated to promote production of pro-IL-1β, and then cleaved to mature IL-1β by NOD-like receptor protein 3 (NLRP3) inflammasome pathway in hippocampus of CUMS mice. After SEN treatment, protein activation related to NLRP3 inflammasome pathway was down-regulated, which inhibited IL-1β secretion. These results demonstrate that SEN plays an important role in treatment CUMS-induced depression in mice, possibly via suppression of pathway activation associated with NLRP3 inflammasome.