title: Long-term effects of post-ischaemic oestrogen on brain injury in a rat transient forebrain ischaemia model.
abstract: BACKGROUND
  The current study was conducted to compare the effects of post-treatment with oestrogen on histological and neurological outcomes after short (7-day) and long (28-day) recovery periods in rats subjected to transient forebrain ischaemia.
  
  
  METHODS
  Male Sprague-Dawley rats were randomly assigned to one of five groups: vehicle (7-day recovery period), vehicle (28-day recovery period), oestrogen (17β-estradiol 200 μg/kg, 7-day), oestrogen (17β-estradiol 200 μg /kg, 28-day), or sham surgical (n = 8 in each group). After forebrain ischaemia was induced with bilateral carotid artery occlusion and haemorrhagic hypotension (mean arterial pressure = 40 mmHg) for 10 min, the brain was reperfused for 7 or 28 days. Either 17β-estradiol or vehicle was injected intravenously during the initial 2 min of reperfusion. To evaluate histological damage, the number of intact neurons per 1 mm in the hippocampal CA1 subfield was counted at 7 or 28 days after transient forebrain ischaemia.
  
  
  RESULTS
  At 7 days after ischaemia, the number of intact neurons in the hippocampal CA1 subfield was significantly greater in the oestrogen group [57.5 (46.5)/mm: median (interquartile range)] than in the vehicle group [10 (19.5) /mm; P = 0.014]. However, there was no difference between groups at 28 days after ischaemia [vehicle: 11 (20)/mm vs. oestrogen: 6 (11)/mm]. The neurological deficit scores in the oestrogen and vehicle groups were not different from the sham group at any point post-ischaemia.
  
  
  CONCLUSIONS
  The current study indicates that post-ischaemic administration of oestrogen provided short-term but not long-term neuroprotective effects in transient forebrain ischaemia in rats.
authors.affiliation: Department of Anesthesia and Intensive Care Medicine, Akita University Graduate School of Medicine, Akita, Japan.
authors.forename: G
authors.initials: G
authors.lastname: Nagasaki
authors.forename: T
authors.initials: T
authors.lastname: Horiguchi
authors.forename: T
authors.initials: T
authors.lastname: Nishikawa
authors.forename: Y
authors.initials: Y
authors.lastname: Masaki
authors.forename: Y
authors.initials: Y
authors.lastname: Tobe
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004967:Estrogens / Q000494:pharmacology*; D006624:Hippocampus / Q000473:pathology*; D002546:Ischemic Attack, Transient / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016548:Prosencephalon / Q000098:blood supply*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004967:Estrogens; D018696:Neuroprotective Agents