Affiliations: [a] Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, Jiangsu, China
| [b] Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, Jiangsu, China
Correspondence:
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Correspondence to: Xiao-Yu Hou, PhD, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, Jiangsu 221004, China. Tel.: +86 516 8326 2620; E-mail: xyhou@xzhmu.edu.cn.
Note: [1] These authors contributed equally to this work.
Abstract: Background:Oligomeric amyloid-β peptide (Aβ) is associated with dysfunctional neuronal networks and neuronal loss in the development of Alzheimer’s disease (AD). Ischemic postconditioning protects against post-ischemic excitotoxicity, oxidative stress, and inflammatory process that have also been implicated in the pathogenesis of AD. Evaluating the roles of ischemic postconditioning in oligomeric Aβ-induced neurotoxicity and underlying signal events may provide potential strategy for medical therapy in AD. Objectives:The aim of the present study was to explore whether and how a brief ischemic postconditioning protects against Aβ neurotoxicity in rat hippocampus. Methods:Oligomeric Aβ25-35 (20 nmol/rat) or Aβ1-42 (5 nmol/rat) was infused by intracerebroventricular injection in adult male Sprague-Dawley rats. Ischemic postconditioning, a brief episode of global brain ischemia (3 min), was conducted at 1, 3, or 7 days after Aβ treatment, respectively. Results:A brief ischemic postconditioning reduced neuronal loss and inhibited the activation of MLK3, MKK3/6, and P38MAPKs in rat hippocampal CA1 and CA3 subfields after Aβ oligomer infusion. An N-methyl-D-aspartate (NMDA) receptor antagonist amantadine, but not non-NMDA receptor antagonist CNQX, reversed the MLK3-MKK3/6-P38MAPK signal events and beneficial effect of ischemic postconditioning on neuronal survival. Such reversion was also realized by NVP-AAM077, a GluN2A-subunit-selective NMDA receptor antagonist. Moreover, posttreatment with low doses of NMDA (5 nmol–40 nmol/rat) suppressed the Aβ-induced P38MAPK signaling and imitated the neuroprotection of ischemic postconditioning against Aβ neurotoxicity. Conclusions:Ischemic postconditioning provides neuroprotection against Aβ neurotoxicity by moderate upregulation of NMDA receptor signaling, especially GluN2A-containing NMDA receptor pathway, and thereafter downregulation of MLK3-MKK3/6-P38MAPK signal events.
