title: Novel antidepressant-like activity of propolis extract mediated by enhanced glucocorticoid receptor function in the hippocampus.
abstract: Propolis is a natural product made by honeybees that has been widely used in folk medicine with a broad spectrum of biological activities. To investigate the antidepressant-like activity of propolis extract, CD-1 mice were administered an ethanol extract of propolis (50, 100, or 200 mg/kg, p.o.) prior to the behavioral test. The propolis extract-treated group showed a dose-dependent decrease in immobility time in the FST and tail suspension test without altering locomotor activity. Propolis extract decreased the limbic hypothalamic-pituitary-adrenal axis response to the FST as indicated by an attenuated corticosterone response and decreased in c-fos immunoreactive neurons in the hippocampal dentate gyrus. Western blot analysis revealed a reduction in hippocampal glucocorticoid receptor (GR) expression following the FST, which was reversed by propolis extract. Propolis extract also increased pGR(S220)/(S234) ratio by a differential phosphorylation in S220 and S234. FST-induced downregulation of cAMP-responsive element binding protein phosphorylation at S133 (pCREB) was restored by propolis extract, showing a strong and positive relationship between pCREB and pGR(S220)/(S234) ratio. These findings suggest that the propolis extract potentiates antidepressant-like activity by enhancing GR function which is one of the therapeutic mechanisms of antidepressant; thus, propolis extract may provide a novel therapy for depression.
authors.affiliation: Division of Bio-Imaging, Chuncheon Center, Korea Basic Science Institute, Chuncheon 200-701, Republic of Korea ; Acupuncture & Meridian Science Research Center, College of Oriental Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea.
authors.forename: Mi-Sook
authors.initials: MS
authors.lastname: Lee
authors.forename: Young Han
authors.initials: YH
authors.lastname: Kim
authors.forename: Wan-Soon
authors.initials: WS
authors.lastname: Park
authors.forename: Won Gyeong
authors.initials: WG
authors.lastname: Ahn
authors.forename: Ok Kyu
authors.initials: OK
authors.lastname: Park
authors.forename: Seung-Hae
authors.initials: SH
authors.lastname: Kwon
authors.forename: Kyoji
authors.initials: K
authors.lastname: Morita
authors.forename: Insop
authors.initials: I
authors.lastname: Shim
authors.forename: Song
authors.initials: S
authors.lastname: Her