Immunolocalization of metabotropic glutamate receptor 7 in the rat olfactory bulb

John (Mark) Kinzie, Michi M. Shinohara, Anthony N. Van Den Pol, Gary Westbrook, Thomas P. Segerson

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Metabotropic glutamate receptors (mGluRs) constitute a large family of G-proteincoupled receptors that are subdivided into three groups based on sequence similarity, pharmacological profiles, and coupling to second messengers. Although mRNAs for seven of the eight mGluRs are expressed in the olfactory system, the localization and function of specific subtypes have not been fully characterized. Mitral cells of the olfactory bulb express mRNA for several mGluRs, including mGluR7, which has been suggested as a presynaptic glutamate autoreceptor. To investigate the immunolocalization of mGluR7 in the olfactory system, we used a polyclonal antiserum specific for the carboxy terminus of the receptor. Mitral cell somata and proximal dendrites were strongly labeled by the mGluR7 antibody. Electron microscopic analysis revealed that most of the mitral cell somatic staining was cytoplasmic. In olfactory bulb glomeruli, immunoreactivity was present in axons and dendrites. In the piriform cortex, diffuse staining was present in layer Ia that was markedly reduced following bulbectomy, consistent with expression of mGluR7 in mitral cell axon terminals. Electron microscopic analysis of this region confirmed the presence of mGluR7 in multiple axon terminals. Distinct labeled fibers in all levels of layer I appeared to originate from labeled piriform cortex pyramidal cells in layers II and III. Our results indicate that mGluR7 is primarily presynaptic at olfactory bulb synapses. However, the postsynaptic localization of mGluR7 at selected synapses indicates that mGluR7 is not targeted exclusively to axonal compartments.

Original languageEnglish (US)
Pages (from-to)372-384
Number of pages13
JournalJournal of Comparative Neurology
Volume385
Issue number3
DOIs
StatePublished - Sep 1 1997

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Olfactory Bulb
Metabotropic Glutamate Receptors
Presynaptic Terminals
Dendrites
Synapses
Electrons
Staining and Labeling
Autoreceptors
Messenger RNA
metabotropic glutamate receptor 7
Pyramidal Cells
Carisoprodol
Second Messenger Systems
Axons
Immune Sera
Glutamic Acid
Pharmacology
Antibodies

Keywords

  • 2-amino-4-phosphonobutyrate
  • Confocal
  • Metabotropic glutamate receptor 7
  • Mitral
  • Presynaptic

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Immunolocalization of metabotropic glutamate receptor 7 in the rat olfactory bulb. / Kinzie, John (Mark); Shinohara, Michi M.; Van Den Pol, Anthony N.; Westbrook, Gary; Segerson, Thomas P.

In: Journal of Comparative Neurology, Vol. 385, No. 3, 01.09.1997, p. 372-384.

Research output: Contribution to journalArticle

Kinzie, John (Mark) ; Shinohara, Michi M. ; Van Den Pol, Anthony N. ; Westbrook, Gary ; Segerson, Thomas P. / Immunolocalization of metabotropic glutamate receptor 7 in the rat olfactory bulb. In: Journal of Comparative Neurology. 1997 ; Vol. 385, No. 3. pp. 372-384.
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