GABA and glutamate are not colocalized in mossy fiber terminals of developing rodent hippocampus

Guoxiang Xiong*, Lei Zhang, Jelena Mojsilovic-Petrovic, Edguardo Arroyo, Jaclynn Elkind, Suhali Kundu, Brian Johnson, Colin J. Smith, Noam A. Cohen, Sean M. Grady, Akiva S. Cohen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

It has been hypothesized that, in the developing rodent hippocampus, mossy fiber terminals release GABA together with glutamate. Here, we used transgenic glutamic acid decarboxylase-67 (GAD67)-GFP expressing mice and multi-label immunohistochemistry to address whether glutamatergic and GABAergic markers are colocalized. We demonstrate that in the dentate gyrus, interneurons positive for GABA/GAD are sparsely distributed along the edge of the hilus, in a different pattern from that of the densely packed granule cells. Co-staining for synaptophysin and vesicular glutamate transporter1 (VGLUT1) in postnatal day 14 brain sections from both mice and rats showed mossy fiber terminals as a group of large (25 μm in diameter) VGLUT1-positive excitatory presynaptic terminals in the stratum lucidum of area CA3a/b. Furthermore, co-staining for synaptophysin and vesicular GABA transporter (VGAT) revealed a group of small-sized (∼0.5 μm in diameter) inhibitory presynaptic terminals in the same area where identified mossy fiber terminals were present. The two types of terminals appeared to be mutually exclusive, and showed no colocalization. Thus, our results do not support the hypothesis that GABA is released as a neurotransmitter from mossy fiber terminals during development.

Original languageEnglish (US)
Pages (from-to)40-49
Number of pages10
JournalBrain research
Volume1474
DOIs
StatePublished - Sep 20 2012

Keywords

  • Granule cell
  • Immunofluorescence
  • Synaptic button
  • Vesicular GABA transporter
  • Vesicular glutamate transporter

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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