GABAA Receptors Reorganize when Layer 4 in Ferret Somatosensory Cortex is Disrupted by Methylazoxymethanol (MAM)

Beata Jablonska, Adam L. Smith, Sidney L. Palmer, Stephen C Noctor, Sharon L. Juliano

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

We established a model of cortical development that arrests the birth of layer 4 cells by injecting methylazoxymethanol (MAM) on embryonic day 33 (E33) in ferrets. This leads to adult somatosensory cortex with a very thin layer 4. Earlier, we determined the relative absence of layer 4 changed the growth and differentiation of the somatosensory cortex and the growth of thalamic afferents into the cortical plate. To identify other features of cortical organization that might be altered after MAM treatment, we assessed the distribution of selected excitatory and inhibitory receptors in area 3b of ferret somatosensory cortex. Initial screening revealed the distribution of several excitatory receptors (NMDA, AMPA, kainate) in E33 MAM-treated cortex was similar to that in normal adult animals. In contrast, the binding pattern of inhibitory GABAA receptors was altered in MAM-treated cortex. Normally, GABAA receptors densely locate in central layers of cortex. In E33 MAM-treated animals, GABAA receptor binding extended superficially, covering a broader area of cortex. Further experiments using antibodies directed against GABA receptors disclosed that pan α GABAA receptors strongly localize to layer 4 in normal area 3b. In E33 MAM-treated cortex, however, GABA receptors extend outside and are located above and below the very thin layer 4. The redistribution of inhibitory receptors suggests that layer 4 plays an important role in regulating thalamic terminations and also in the resulting ability to refine processing of incoming stimuli.

Original languageEnglish (US)
Pages (from-to)432-440
Number of pages9
JournalCerebral Cortex
Volume14
Issue number4
DOIs
StatePublished - Apr 2004
Externally publishedYes

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Keywords

  • Cerebral cortex
  • Development
  • GABA subunit
  • Glutamate receptors
  • MAM
  • Receptor binding
  • Thalamus

ASJC Scopus subject areas

  • Neuroscience(all)

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