The Journal of Neuroscience, April 15, 2001, 21(8):2738-2748
Spatiotemporal Dynamics of Brain-Derived Neurotrophic Factor mRNA
Induction in the Vestibulo-Olivary Network during Vestibular
Compensation
Yue Xin
Li1,
Takanori
Hashimoto1,
Wataru
Tokuyama2,
Yasushi
Miyashita1, 2, 3, and
Hiroyuki
Okuno2
1 Mind Articulation Project, International Cooperative
Research Project, Japan Science and Technology Corporation, Yushima,
Tokyo 113-0034, Japan, 2 Department of Physiology,
University of Tokyo School of Medicine, Hongo, Tokyo 113-0033, Japan,
and 3 National Institute for Physiological Sciences,
Myodaiji, Okazaki 444-8585, Japan
Vestibular compensation, which is the behavioral recovery from
vestibular dysfunction produced by unilateral labyrinthectomy (UL), is
attributed to functional and structural reorganization of neural
networks in the central vestibular system. To assess the possible
contribution of brain-derived neurotrophic factor (BDNF) to this
recovery process, we investigated changes in mRNA expression levels in
the central vestibular system after UL. We evaluated BDNF mRNA
expression levels by quantitative reverse transcription-PCR and
in situ hybridization. We found that BDNF mRNA is
differentially induced in the medial vestibular nucleus ipsilateral to
UL and in the prepositus hypoglossi and inferior olive on the
contralateral side. The BDNF mRNA induction lasted for at least 24 hr
and returned to the basal expression level within 72 hr after UL. In
contrast to BDNF mRNA induction, the expression of an immediate-early
gene, c-fos, quickly reached the maximum level at 3 hr
and decreased to the basal level within 24 hr after UL. Neither BDNF or
c-fos induction was observed in sham-operated animals.
The persistent induction of BDNF after UL temporally corresponded to
early behavioral manifestations of vestibular compensation. We further
found that trkB mRNA was expressed in the central
vestibular network at high levels, although its expression levels did
not change over time after UL. Because BDNF is implicated in regulating
synaptic structure and function, these results provide support for the
hypothesis that BDNF is involved in neuronal reorganization that allows
vestibular compensation.
Key words:
vestibular compensation; labyrinthectomy; lesion-induced
plasticity; brain-derived neurotrophic factor; trkB; quantitative RT-PCR
Copyright © 2001 Society for Neuroscience 0270-6474/01/2182738-11$05.00/0