Daidzein

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright a b s t r a c t Phytoestrogens are a group of plant-derived compounds that include mainly isoflavones like daidzein. Phytoestrogens prevent neuronal damage and improve outcome in experimental stroke; however, the mechanisms of this neuroprotective action have not been fully elucidated. In this context, it has been postulated that phytoestrogens might activate the peroxisome proliferator-activated receptor-c (PPARc), which exerts neuroprotective effects in several settings. The aim of this study was to determine whether the phytoestrogen daidzein elicits beneficial actions in neuronal cells by mechanisms involving activation of PPARc. Our results show that daidzein (0.05–5 lM) decreases cell death induced by exposure to oxygen–glucose deprivation (OGD) from rat cortical neurons and that improves synaptic function, in terms of increased synaptic vesicle recycling at nerve terminals, being both effects inhibited by the PPARc antagonist T0070907 (1 lM). In addition, this phytoestrogen activated PPARc in neuronal cultures, as shown by an increase in PPARc transcriptional activity. Interestingly, these effects were not due to binding to the receptor ligand site, as shown by a TR-FRET PPARc competitive binding assay. Conversely, daidzein increased PPARc nuclear protein levels and decreased cytosolic ones, suggesting nuclear trans-location. We have used the receptor antagonist (RE) fulvestrant to study the neuroprotective participation of daidzein via estrogen receptor and at least in our model, we have discarded this pathway. These results demonstrate that the phytoestrogen daidzein has cytoprotective properties in neurons, which are due to an increase in PPARc activity not mediated by direct binding to the receptor ligand-binding domain but likely due to post-translational modifications affecting its subcellular location and not depending to the RE and it is not additive with the agonist rosiglitazone.