Abstract

The flavonoid quercetin is considered to have beneficial effects on human health. We recently have shown that quercetin-enriched foods reduced the duration of immobility time in a rat forced swimming test, indicating that dietary quercetin is promising as an antidepressant-like factor, whereas its mechanism of action is poorly understood. The aim of this study is to investigate the effects of quercetin on water immersion-restraint (WIR), stress-induced hypothalamic-pituitary-adrenal (HPA) axis activation, which is a major component of stress response and plays an important role in the pathology of depression. Quercetin administration to rats significantly suppressed WIR stress-induced increase of plasma corticosterone and adrenocorticotropic hormone levels as well as the mRNA expression of corticotropin-releasing factor (CRF) in the hypothalamic region. In addition, quercetin modulated the DNA binding activities of glucocorticoid receptor and phosphorylated cyclic adenosine 3',5'-monophosphate (cAMP) response element binding protein as well as the phosphorylation of extracellular signal-regulated kinase 1/2 in the hypothalamic region, all of which are known to regulate the expression of CRF mRNA. Taken together, these results suggest that dietary quercetin attenuates the HPA axis activation by the suppression of the CRF mRNA expression.

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