Quantitative changes in gene expression of glutamate receptor subunits/subtypes in the vestibular nucleus, inferior olive and flocculus before and following unilateral labyrinthectomy in the rat: real-time quantitative PCR method |
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| Authors: | Horii A Smith P F Darlington C L |
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| Institution: | (1) Vestibular Research Group, Department of Pharmacology, School of Medical Sciences, University of Otago Medical School, Dunedin, New Zealand,;(2) Department of Otolaryngology and Sensory Organ Surgery, Osaka University Medical School, Osaka, Japan,;(3) Vestibular Research Group, Department of Psychology and the Neuroscience Research Centre, University of Otago, Dunedin, New Zealand,;(4) Present address: Department of Otolaryngology and Sensory Organ Surgery, Osaka University Medical School, Suita, Osaka 565-0871, Japan (e-mail: ahorii@ent.med.osaka-u.ac.jp, Tel.: +81-6-68793951, Fax: +81-6-68793959), |
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| Abstract: | Spontaneous recovery from the oculomotor and postural symptoms of unilateral labyrinthectomy (UL) is known as vestibular
compensation, which is a useful model for investigation of the mechanisms of lesion-induced CNS plasticity. In the present
study, to elucidate the molecular biological basis of vestibular compensation, we investigated changes in the mRNA expression
of glutamate receptor subunit/subtypes in the rat central vestibular system, including the vestibular nucleus complex (VNC),
inferior olive (IO), and cerebellar flocculus following UL, using a real-time quantitative polymerase chain reaction (PCR)
method. In normal control animals, regional differences in the expression of several glutamate receptor subunit/subtypes,
e.g., NR1 and NR2A subunits of the N-methyl-D-aspartic acid (NMDA) receptor, GluR2 and KA2 subtypes of non-NMDA receptors, and mGluR1 and mGluR7 metabotropic glutamate
receptors, were consistent with previous results from studies using in situ hybridization histochemistry, suggesting that
the real-time quantitative PCR method was a reliable procedure for evaluation of changes in mRNA expression. In the vestibular
nucleus complex, NR2A, GluR2 and mGluR7 mRNA were ipsilaterally downregulated by 6 h following UL (P<0.05, P<0.05 and P<0.01, respectively). In the inferior olive, no changes in gene expression were observed. In the ipsilateral flocculus, KA2
mRNA expression was increased by 50 h post-UL (P<0.05). However, in the contralateral flocculus, mGluR1 mRNA was downregulated by 6 h post-UL (P<0.005). Both the increase in KA2 mRNA expression in the ipsilateral flocculus and the decrease in mGluR1 mRNA expression
in the contralateral flocculus may have had the effect of reducing Purkinje cell inhibition of ipsilateral VNC neurons, thereby
contributing to the rebalancing of spontaneous resting activity between the ipsilateral and contralateral VNCs. It is suggested
that such changes in the activities of the floccular-VNC pathways may be important to the vestibular compensation process.
Electronic Publication |
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| Keywords: | Gene expression Glutamate receptor Molecular mechanisms Plasticity Vestibular compensation |
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