Cognitive deficits associated with alteration of synaptic metaplasticity precede plaque deposition in AβPP23 transgenic mice

Claudia Balducci, Raffaella Tonini, Elisa Zianni, Cristiano Nazzaro, Fabio Fiordaliso, Monica Salio, Lorenzo Vismara, Fabrizio Gardoni, Monica Di Luca, Mirjana Carli, Gianluigi Forloni

Research output: Contribution to journalArticle

Abstract

Synaptic dysfunction is an early event in the development of Alzheimer's disease (AD) and relates closely to the cognitive impairment characterizing this neurodegenerative process. A causative association has been proposed, largely on the basis of in vitro studies, between memory decline, soluble amyloid-β (Aβ) oligomers and alterations of glutamatergic neurotransmission. We aimed here to characterize in vivo N-methyl-D-aspartate receptor (NMDAR)-mediated signaling, at an early stage of AD, before extracellular amyloid plaques are deposited. We assessed the functional link between cognitive abilities and NMDAR-mediated pharmacological responses of six-month-old AβPP23 transgenic mice (AβPP23tg), overexpressing the human amyloid-β protein precursor carrying the Swedish double mutation. We found evidence of cognitive impairments in these mice, indicated by deficits in the delayed-non-matching-to-place task. Alterations of NMDAR-mediated signaling in this mouse model were confirmed by the reduced sensitivity of motor-activation and working memory to pharmacological inhibition of NMDAR activity. At the molecular level, AβPP23tg mice show hippocampal alterations in the trafficking of synaptic NMDAR subunits NR2A and NR2B and at an ultrastructural analysis show Aβ oligomers intracellularly localized in the synaptic compartments. Importantly, the behavioral and biochemical alterations of NMDAR signaling are associated with the inhibition of long-term synaptic potentiation and inversion of metaplasticity at CA1 synapses in hippocampal slices from AβPP23tg mice. These results indicate a general impairment of synaptic function and learning and memory in young AβPP23tg mice with Aβ oligomers but no amyloid plaques.

Original languageEnglish
Pages (from-to)1367-1381
Number of pages15
JournalJournal of Alzheimer's Disease
Volume21
Issue number4
DOIs
Publication statusPublished - 2010

Keywords

  • AβPP23 Tg mice
  • Alzheimer's disease
  • amyloid-β oligomers
  • NMDA glutamate receptors
  • spatial memory
  • synaptic plasticity

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Geriatrics and Gerontology
  • Clinical Psychology

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