P. Popper et al., Expression of BDNF and TrkB mRNAs in the crista neurosensory epithelium and vestibular ganglia following ototoxic damage, BRAIN RES, 846(1), 1999, pp. 40-51
Following ototoxic lesion with the aminoglycoside gentamicin, the vestibula
r neurosensory epithelia undergo degeneration and then Limited spontaneous
regeneration. The spatio-temporal expression of brain-derived neurotrophic
factor (BDNF) and of its high affinity receptor (trkB) mRNA was investigate
d in the vestibular end organs and ganglia of chinchillas following gentami
cin ototoxicity. In the vestibular ganglia of untreated chinchillas, the le
vel of expression of BDNF mRNA is low. At 1 and 2 weeks after intraotic tre
atment with gentamicin, BDNF mRNA levels in the vestibular ganglia were ele
vated significantly compared to untreated chinchillas and chinchillas 4 wee
ks after treatment. At 4 weeks after gentamicin treatment, BDNF mRNA levels
were at intact levels of expression. In the crista ampullaris, high levels
of BDNF transcripts were found in the untreated chinchillas. At 1 and 2 we
eks after treatment, when only supporting cells are present in the crista,
BDNF mRNA was undetectable. Four weeks after aminoglycoside treatment BDNF
mRNA was present in the epithelium but at lower levels than in the intact e
pithelium. In contrast to its ligand, high levels of trkB mRNA hybridizatio
n were present in the vestibular ganglia of untreated chinchillas and trkB
mRNA levels did not change following gentamicin treatment. In the vestibula
r epithelia, trkB mRNA was not detected either in the intact epithelium or
after gentamicin ototoxicity. These data suggest that BDNF may be involved
in the maintenance of the vestibular ganglia and contribute to neurite outg
rowth to new and repaired hair cells following ototoxic damage. (C) 1999 El
sevier Science B.V. All rights reserved.