title: GABA and glutamate are not colocalized in mossy fiber terminals of developing rodent hippocampus.
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 (2-5 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.
authors: Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. xiong@email.chop.edu
authors: Guoxiang
authors: G
authors: Xiong
authors: Lei
authors: L
authors: Zhang
authors: Jelena
authors: J
authors: Mojsilovic-Petrovic
authors: Edguardo
authors: E
authors: Arroyo
authors: Jaclynn
authors: J
authors: Elkind
authors: Suhali
authors: S
authors: Kundu
authors: Brian
authors: B
authors: Johnson
authors: Colin J
authors: CJ
authors: Smith
authors: Noam A
authors: NA
authors: Cohen
authors: Sean M
authors: SM
authors: Grady
authors: Akiva S
authors: AS
authors: Cohen
mesh_terms: D000818:Animals; D015153:Blotting, Western; D005455:Fluorescent Antibody Technique; D018698:Glutamic Acid / Q000096:biosynthesis*; D006624:Hippocampus / Q000254:growth & development* / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D019599:Mossy Fibers, Hippocampal / Q000254:growth & development* / Q000378:metabolism*; D051381:Rats; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis*
chemical_list: D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid