Activation of Canonical Notch Signaling Pathway Is Involved in the Ischemic Tolerance Induced by Sevoflurane Preconditioning in Mice

* Ph.D. Candidate, † Associate Professor, ‡ Associate Professor and Chief, § Research Assistant, # Professor, Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China. || Professor, Institute of Mental Health Research, Department of Psychiatry and Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.
Anesthesiology (Impact Factor: 5.88). 08/2012; 117(5):996-1005. DOI: 10.1097/ALN.0b013e31826cb469
Source: PubMed


: 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.
: 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).
: 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.
: Sevoflurane preconditioning-induced protective effects against transient cerebral ischemic injuries are mediated by the activation of canonical Notch signaling pathway in mice.

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    • "I/R) It is still controversial whether the activated canonical Notch signaling is beneficial to the ischemic cerebral tissues. Many researchers have found that the activation of Notch signaling was involved in the ischemic tolerance induced by inhalation anesthetics preconditioning (Zhang et al. 2014; Yang et al. 2012). However, other reports was consistent with the opinion that Notch signaling can induce neuronal cell death (Arumugam et al. 2011). "
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