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Developmental expression of NMDA and AMPA receptor subunits in vestibular nuclear neurons that encode gravity‐related horizontal orientations
Author(s) -
Tse YiuChung,
Lai ChunHong,
Lai SukKing,
Liu JianXiang,
Yung Ken K.L.,
Shum Daisy K.Y.,
Chan YingShing
Publication year - 2008
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21688
Subject(s) - ampa receptor , ionotropic effect , ionotropic glutamate receptor , biology , glutamatergic , glutamate receptor , protein subunit , nmda receptor , vestibular nuclei , neuroscience , microbiology and biotechnology , receptor , medicine , vestibular system , endocrinology , biochemistry , gene
We examined the expression profile of subunits of ionotropic glutamate receptors [ N ‐methyl‐D‐aspartate (NMDA) and α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole‐proprionate (AMPA)] during postnatal development of connectivity in the rat vestibular nucleus. Vestibular nuclear neurons were functionally activated by constant velocity off‐vertical axis rotation, a strategy to stimulate otolith organs in the inner ear. These neurons indicated Fos expression as a result. By immunodetection for Fos, otolith‐related neurons that expressed NMDA/AMPA receptor subunits were identified as early as P7, and these neurons were found to increase progressively up to adulthood. Although there was developmental invariance in the percentage of Fos‐immunoreactive neurons expressing the NR1, NR2A, GluR1, or GluR2/3 subunits, those expressing the NR2B subunit decreased from P14 onward, and those expressing the GluR4 subunit decreased in adults. These double‐immunohistochemical data were corroborated by combined immuno‐/hybridization histochemical data obtained from Fos‐immunoreactive neurons expressing NR2B mRNA or GluR4 mRNA. The staining of both NR2B and GluR4 in the cytoplasm of these neurons decreased upon maturation. The percentage of Fos‐immunoreactive neurons expressing the other ionotropic glutamate receptor subunits (viz. NR1, NR2A, GluR1, and GluR2/3) remained relatively constant throughout postnatal maturation. Triple immunofluorescence further demonstrated coexpression of NR1 and NR2 subunits in Fos‐immunoreactive neurons. Coexpression of NR1 subunit with each of the GluR subunits was also observed among the Fos‐immunoreactive neurons. Taken together, the different expression profiles of ionotropic glutamate receptor subunits constitute the histological basis for glutamatergic neurotransmission in the maturation of central vestibular connectivity for the coding of gravity‐related horizontal head movements. J. Comp. Neurol. 508:343–364, 2008. © 2008 Wiley‐Liss, Inc.