title: Icariin attenuates chronic mild stress-induced dysregulation of the LHPA stress circuit in rats.
abstract: Chronic mild stress (CMS) is suggested to develop dysregulation of the limbic-hypothalamic-pituitary-adrenal (LHPA) stress circuit. Icariin, a major constituent of flavonoids isolated from Epimedium brevicornum, has been previously confirmed to rescue the HPA axis abnormalities in animal models of depression. However, antidepressant treatment of icariin on corticotropin-releasing factor (CRF) system within the LHPA stress circuit and its interaction with serotonergic receptor are still seldom studied in CMS model of animals. The present study further investigated the effects of CMS procedure and subsequent icariin treatment on mRNA and protein levels of CRF, CRF receptor 1 (CRFR1) and CRF binding protein (CRFBP), as well as sucrose intake in rats. Moreover, the levels of cyclic adenosine 3',5'-monophosphate (cAMP) response element binding protein (CREB), glucocorticoid receptor (GR) and 5-hydroxytryptamine 1A receptor (5-HTR1A) in hypothalamus, hippocampus and frontal cortex were simultaneously evaluated for their participations in CRF system in this model. We found that CMS procedure significantly increased CRF expression levels in the brain regions, and decreased GR and 5-HTR1A in hippocampus and frontal cortex, with sucrose intake reduction representing the hedonic deficit in rats. Icariin restored these alterations in CMS rats. These results confirmed the hypothesis that icariin exerted antidepressant-like effect via its regulation of central CRF system. And hippocampus was suggested as an important neural area controlling the LHPA stress circuit in icariin-treated CMS rats. These findings for the first time proved that the potential molecular mechanism of antidepressant action of icariin was targeted on the interaction of the LHPA stress circuit and serotonergic function in CMS rats.
authors.affiliation: State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Pan
authors.forename: Fu-Meng
authors.initials: FM
authors.lastname: Wang
authors.forename: Li-Qin
authors.initials: LQ
authors.lastname: Qiang
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Zhang
authors.forename: Ling-Dong
authors.initials: LD
authors.lastname: Kong
mesh_terms: D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D007027:Hypothalamic Diseases / Q000517:prevention & control; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D008032:Limbic System / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D010913:Pituitary-Adrenal System / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D044282:Receptor, Serotonin, 5-HT1A / Q000235:genetics / Q000378:metabolism; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects* / Q000235:genetics; D013315:Stress, Psychological / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D004365:Drugs, Chinese Herbal; D005419:Flavonoids; D018019:Receptors, Corticotropin-Releasing Hormone; D044282:Receptor, Serotonin, 5-HT1A; D003346:Corticotropin-Releasing Hormone; C056599:icariin