title: Post-ischemic estradiol treatment reduced glial response and triggers distinct cortical and hippocampal signaling in a rat model of cerebral ischemia.
abstract: BACKGROUND
  Estradiol has been shown to exert neuroprotective effects in several neurodegenerative conditions, including cerebral ischemia. The presence of this hormone prior to ischemia attenuates the damage associated with such events in a rodent model (middle cerebral artery occlusion (MCAO)), although its therapeutic value when administered post-ischemia has not been assessed. Hence, we evaluated the effects of estradiol treatment after permanent MCAO (pMCAO) was induced in rats, studying the PI3K/AKT/GSK3/β-catenin survival pathway and the activation of SAPK-JNK in two brain areas differently affected by pMCAO: the cortex and hippocampus. In addition, we analyzed the effect of estradiol on the glial response to injury.
  
  
  METHODS
  Male rats were subjected to pMCAO and estradiol (0.04 mg/kg) was administered 6, 24, and 48 h after surgery. The animals were sacrificed 6 h after the last treatment, and brain damage was evaluated by immunohistochemical quantification of 'reactive gliosis' using antibodies against GFAP and Iba1. In addition, Akt, phospho-Akt(Ser473), phospho-Akt(Thr308), GSK3, phospho-GSK3(Ser21/9), β-catenin, SAPK-JNK, and pSAPK-JNK(Thr183/Tyr185) levels were determined in western blots of the ipsilateral cerebral cortex and hippocampus, and regional differences in neuronal phospho-Akt expression were determined by immunohistochemistry.
  
  
  RESULTS
  The increases in the percentage of GFAP- (5.25-fold) and Iba1- (1.8-fold) labeled cells in the cortex and hippocampus indicate that pMCAO induced 'reactive gliosis'. This effect was prevented by post-ischemic estradiol treatment; diminished the number of these cells to those comparable with control animals. pMCAO down-regulated the PI3K/AkT/GSK3/β-catenin survival pathway to different extents in the cortex and hippocampus, the activity of which was restored by estradiol treatment more efficiently in the cerebral cortex (the most affected region) than in the hippocampus. No changes in the phosphorylation of SAPK-JNK were observed 54 h after inducing pMCAO, whereas pMCAO did significantly decrease the phospho-Akt(Ser473) in neurons, an effect that was reversed by estradiol.
  
  
  CONCLUSIONS
  The present study demonstrates that post-pMCAO estradiol treatment attenuates ischemic injury in both neurons and glia, events in which the PI3K/AKT/GSK3/β-catenin pathway is at least partly involved. These findings indicate that estradiol is a potentially useful treatment to enhance recovery after human ischemic stroke.
authors: Centro de Biología Molecular "Severo Ochoa", CSIC-UAM, Univ, Autónoma de Madrid, Madrid, Spain.
authors: Maria Jose
authors: MJ
authors: Pérez-Álvarez
authors: Maria Del Carmen
authors: Mdel C
authors: Maza
authors: Marta
authors: M
authors: Anton
authors: Lara
authors: L
authors: Ordoñez
authors: Francisco
authors: F
authors: Wandosell
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D002540:Cerebral Cortex / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D004195:Disease Models, Animal; D004958:Estradiol / Q000008:administration & dosage*; D006624:Hippocampus / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D008297:Male; D009457:Neuroglia / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D016896:Treatment Outcome
chemical_list: D004958:Estradiol