In vivo uptake of β-amyloid by non-plaque associated microglia

Curr Alzheimer Res. 2012 Oct;9(8):890-901. doi: 10.2174/156720512803251084.

Abstract

The role of microglia in β-amyloid (Aβ) deposition or clearance in the Alzheimer's disease (AD) brain remains unclear. Previous in vivo studies have focused primarily on the association of microglia with Aβ-positive parenchymal plaques, but have given little consideration to the possible interaction between Aβ and non-plaque associated microglia. Further, it is not known if microglia play a direct role in mediating Aβ uptake following anti-aggregant treatment. We report here the identification of Aβ-positive processes throughout the cortex and hippocampus of TgCRND8 mice expressing the human Swedish (KM670/671NL) and Indiana (V717F) amyloid precursor protein mutations, which localized to ionized calcium binding protein-1-positive resident microglia that were not associated with extracellular plaques. Oral administration of 1-deoxy-1-fluoro-scyllo-inositol, a scyllo-inositol analogue, to TgCRND8 mice improved spatial memory impairments and suppressed amyloid pathology in a dose-dependent manner. Further, treatment with 1-deoxy-1- fluoro-scyllo-inositol significantly increased hippocampal intra-microglial Aβ levels without stimulating microglial proliferation or peripheral macrophage recruitment. These results reveal a novel, beneficial role for non-plaque associated microglia in the regulation of cerebral Aβ levels in a mouse model of AD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease / metabolism*
  • Alzheimer Disease / pathology
  • Amyloid beta-Peptides / metabolism*
  • Animals
  • Brain / drug effects
  • Brain / metabolism
  • Brain / pathology*
  • Disease Models, Animal
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Immunohistochemistry
  • Inositol / pharmacology
  • Male
  • Maze Learning / drug effects
  • Mice
  • Mice, Transgenic
  • Microglia / metabolism*
  • Neuroprotective Agents / pharmacology

Substances

  • Amyloid beta-Peptides
  • Neuroprotective Agents
  • scyllitol
  • Inositol