title: Activation of canonical notch signaling pathway is involved in the ischemic tolerance induced by sevoflurane preconditioning in mice.
abstract: BACKGROUND
  A wealth of evidence has demonstrated that sevoflurane preconditioning induces brain ischemic tolerance, but the mechanism remains poorly understood. This study was designed to investigate the role of canonical Notch signaling in the neuroprotection induced by sevoflurane preconditioning in a mouse model.
  
  
  METHODS
  C57BL/6 mice were pretreated with 1-h sevoflurane exposure at a dose of 2.5% for 5 consecutive days. Twenty-four hours after the last exposure, all mice were subjected to focal cerebral ischemia by right middle cerebral artery occlusion for 60 min. Neurobehavioral scores, brain infarct volumes, and cellular apoptosis were determined at 72 h after reperfusion (n = 10 per group). The activation of Notch signaling was evaluated (n = 5 per group), and its role in ischemic tolerance was assessed by intraperitoneal administration of γ-secretase inhibitor DAPT (100 mg/kg, n = 10 per group) and conditional Notch-RBP-J knockout technique (n = 8 per group).
  
  
  RESULTS
  Sevoflurane preconditioning reduced brain infarct volumes (42.5%), improved neurologic outcomes (P < 0.01 vs. control), and attenuated neuronal cell apoptosis (cells positive for terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labeling reduced to 21.2%). The expression of Notch1 intracellular domain (1.35 folds) and the transcriptions of Hes1 (1.95 times) and Hes5 (1.48 times) were up-regulated. DAPT augmented the brain infarcts (1.64-fold) and decreased neurologic scores (P = 0.43 vs. sevoflurane) in sevoflurane-preconditioned mice. Brain infarct volumes, neurobehavioral scores, and apoptotic cell numbers showed no significance between Notch knockout mice with sevoflurane preconditioning and wild-type mice without preconditioning.
  
  
  CONCLUSIONS
  Sevoflurane preconditioning-induced protective effects against transient cerebral ischemic injuries are mediated by the activation of canonical Notch signaling pathway in mice.
authors.affiliation: Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Qianzi
authors.initials: Q
authors.lastname: Yang
authors.forename: Wenjun
authors.initials: W
authors.lastname: Yan
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Lihong
authors.initials: L
authors.lastname: Hou
authors.forename: Hui
authors.initials: H
authors.lastname: Dong
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Hailong
authors.initials: H
authors.lastname: Dong
authors.forename: Shiquan
authors.initials: S
authors.lastname: Wang
authors.forename: Xia
authors.initials: X
authors.lastname: Zhang
authors.forename: Lize
authors.initials: L
authors.lastname: Xiong
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism* / Q000517:prevention & control* / Q000628:therapy; D019194:Ischemic Preconditioning / Q000379:methods*; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology* / Q000627:therapeutic use; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011897:Random Allocation; D051881:Receptor, Notch1 / Q000096:biosynthesis*; D000077149:Sevoflurane; D060449:Wnt Signaling Pathway / Q000187:drug effects / Q000502:physiology*
chemical_list: D008738:Methyl Ethers; C497762:Notch1 protein, mouse; D051881:Receptor, Notch1; D000077149:Sevoflurane