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Evidence for synaptic stripping by cortical microglia
Author(s) -
Trapp Bruce D.,
Wujek Jerome R.,
Criste Gerson A.,
Jalabi Walid,
Yin Xinghua,
Kidd Grahame J.,
Stohlman Stephen,
Ransohoff Richard
Publication year - 2007
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.20462
Subject(s) - biology , neuroscience , microglia , immunology , inflammation
Recent studies have described significant demyelination and microglial activation in the cerebral cortex of brains from multiple sclerosis patients. To date, however, experimental models of cortical demyelination or cortical inflammation have not been extensively studied. In this report we describe focal cortical inflammation induced by stereotaxic injection of killed bacteria (BCG), followed 1 month later by subcutaneous injection of the same antigen, a protocol that overcomes the immune privilege of the cortex. Intracerebral BCG injection produced focal microglial activation at the injection site (termed acute lesion). Ten days after peripheral challenge (termed immune‐mediated lesion), larger areas and higher densities of activated microglia were found near the injection site. In both paradigms, activated microglia and/or their processes closely apposed neuronal perikarya and apical dendrites. In the immune‐mediated lesions, ∼45% of the axosomatic synapses was displaced by activated microglia. Upon activation, therefore, cortical microglial migrate to and strip synapses from neuronal perikarya. Since neuronal pathology was not a feature of either the acute or immune‐mediated lesion, synaptic stripping by activated microglia may have neuroprotective consequences. © 2006 Wiley‐Liss, Inc.