M. Montcouquiol et al., A ROLE FOR BDNF IN EARLY POSTNATAL RAT VESTIBULAR EPITHELIA MATURATION - IMPLICATION OF SUPPORTING CELLS, European journal of neuroscience, 10(2), 1998, pp. 598-606
The early development of the inner ear is largely determined by two me
mbers of the neurotrophic family: brain-derived neurotrophic factor (B
DNF) and neurotrophin 3 (NT-3). Little information is available on the
role of these neurotrophins during the late stages of vestibular deve
lopment in the rat which take place during the first postnatal weeks.
At this period where terminal synaptogenesis and maturation occur, we
have investigated the expression and the activity of BDNF, the most im
portant neurotrophin in the vestibular system. Using different experim
ental approaches, we show that BDNF is released by vestibular epitheli
a on postnatal day 3 (P3) and continues to have a trophic effect on ve
stibular neurones in vitro. Immunocytochemistry coupled to confocal mi
croscopy revealed a remarkable evolution in BDNF localization during l
ater stages of development. Whereas BDNF is present in both supporting
cells and hair cells at P3, its distribution gradually changed and is
highly compartmentalized within the upper part of supporting cells at
P8 and P15. In parallel, we observed the presence of a truncated form
of the BDNF receptor in sensory hair cells. These results suggest an
original role for supporting cells, which could be involved in the rel
ease of BDNF during the late stages of synaptogenesis in mammalian ves
tibular epithelia. In particular, BDNF could participate to the set up
of the calyx, a specific nerve structure surrounding type I vestibula
r hair cells.