Philippe P. Lefebvre

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Destruction of auditory hair cells results in a subsequent loss of auditory neurons. In situ hybridization and neuronal cell culture studies as well as analyses of the inner ears of neurotrophin and neurotrophin receptor gene knockout mice have shown that NT-3 and BDNF mediate both the development and survival of auditory neurons. In this study guinea pigs(More)
Developing cochleovestibular ganglion (CVG) neurons depend upon interaction with the otocyst, their peripheral target tissue, for both trophic support and tropic guidance. RT-PCR of E11 through E14 otocyst-CVG RNA extracts have shown that NGF as well as BDNF and NT-3 are expressed in the developing inner ear (in situ RT-PCR on tissue sections of E12(More)
During the first week of postnatal development, the innervation of the organ of Corti changes from an immature to an adult pattern. Dissociated cell cultures of early postnatal spiral ganglia were used to investigate the effects of nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) on maturing auditory neurones.(More)
Auditory hair cells produce trophic factors that directly affect maturation and survival of auditory neurons. These factors include two members of the neurotrophin family: brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). Loss of hair cells, as a result of either noise trauma or ototoxic damage, results in the degeneration of auditory(More)
Hair cell (HC) and supporting cell (SC) productions are completed during early embryonic development of the mammalian cochlea. This study shows that acutely dissociated cells from the newborn rat organ of Corti, developed into so-called otospheres consisting of 98% nestin (+) cells when plated on a non-adherent substratum in the presence of either epidermal(More)
The organ of Corti is highly ordered, with a single row of inner hair cells and three rows of outer hair cells. The number of hair cells produced was thought to be limited by the time of their terminal mitosis (i.e. E14 in the mouse). However, exogenous application of retinoic acid has been shown to stimulate the formation of supernumerary hair cells in(More)
Auditory neurons depend upon the integrity of both their peripheral (auditory hair cells) and central (cochlear nucleus) targets for survival. One proposed trophic mechanism is the production of neurotrophin-3 (NT-3) by auditory hair cells. Modiolus-spiral ganglion explants from adult rats that closely mirror cell-cell interactions and in vivo tissue(More)
In the developing inner ear, the existence of a neuronal death and of a peripheral target-derived trophic effect on cochleovestibular neurons has been documented. Using cultures of rat cochleovestibular neurons, we show that the E12 otic vesicle releases a factor promoting the survival and the neuritogenesis of these neurons, and that this effect is(More)
RT-PCR was used to assay for growth factors and receptors from seven different protein families in cochlea tissues of the juvenile rat. There was a broad representation of the growth factor families in all the cochlea tissues examined, though the organ of Corti and stria vascularis expressed a greater variety than the spiral ganglion. This broad expression(More)
NGF binding patterns reflect the presence of receptors for this growth factor. High specific binding of 125I 2.5 S-NGF was observed for the 11 gestation day (gd) statoacoustic ganglion (SAG) with lower levels recorded for both 14 gd acoustic ganglion (AG) and vestibular ganglion (VG) samples. Fourteen day AG cells were more than twice as active for binding(More)