Potentiation of NMDA receptor-mediated synaptic responses by microglia

Shigeki Moriguchi, Yoshito Mizoguchi, Yoshiro Tomimatsu, Yoshinori Hayashi, Tomoko Kadowaki, Yoshifumi Kagamiishi, Nobuo Katsube, Kenji Yamamoto, Kazuhide Inoue, Shigenori Watanabe, Junichi Nabekura, Hiroshi Nakanishi

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)

Abstract

To study the influence of microglia on glutamatergic synaptic transmission in the acute phase of neuronal injury, we first examined the effects of primary cultured microglia transferred onto the organotypic cortical slice cultures. In these microglia-transferred cortical slice cultures, stimulation of the subcortical white matter induced fast excitatory postsynaptic potentials followed by N-methyl-D-aspartate (NMDA) receptor-mediated plateau-like potentials that were never observed in control slice cultures. A similar potentiation of NMDA receptor-mediated postsynaptic responses was also observed by an application of a microglial-conditioned medium (MCM, 10% v/v) in acute cortical slices. These effects of MCM disappeared after boiling or incubation with proteinase K. After fractionation of MCM by anion-exchange chromatography, the enhancing activity of each fraction was quantitated electrophysiologically. When each fraction was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the fraction 24 which showed the most potent enhancing activity on NMDA receptor-mediated responses contained a relatively strong protein band with a molecular mass of approximately 70 kDa. MCM also enhanced both glutamate- and NMDA-induced inward currents recorded from acutely isolated cortical neurons. It was also noted that glutamate and NMDA induced transient large inward currents during an application of MCM, which were never observed in the control condition. These observations strongly suggest that NMDA receptor-mediated responses can be potentiated by both heat- and protease-labile (presumably 70-kDa proteins) molecules released from microglia.

Original languageEnglish
Pages (from-to)160-169
Number of pages10
JournalMolecular Brain Research
Volume119
Issue number2
DOIs
Publication statusPublished - 2003 Nov 26
Externally publishedYes

Keywords

  • Microglia
  • NMDA receptor
  • Rat
  • Slice preparation
  • Synaptic transmission

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience

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