Developmental changes in growth factors released by the embryonic inner ear
Recent studies have demonstrated a role for neurotrophins in regulating the survival of developing auditory and vestibular neurons. However, the developmental time-course for neurotrophin production and release by inner ear tissues has not been defined. In the present study, neurotrophin-like activity was evaluated from culture medium conditioned by early- or midembryonic stage inner ears. Examination of the proteinaceous properties of conditioned medium revealed a developmental change in growth factor release by the inner ear. Neurotrophin-like molecules were not detected in medium conditioned by early stage otocysts. In contrast, neurotrophin-like bioactivity was detected in medium conditioned by middevelopmental stage inner ears. Western blot analysis revealed that NT-3 was released by the rat inner ear at midstages of inner ear development. ELISA measurements revealed that both NT-3 and BDNF are produced by the middevelopmental stage inner ear, and that NT-3 protein levels are higher than BDNF levels. These results suggest that there are developmental changes in the release of growth factors by the inner ear.
Bianchi, L.M., R. Dolnick, A.M. Medd, and C.S. Cohan. 1998. "Developmental changes in growth factors released by the embryonic inner ear." Experimental Neurology 150(1): 98-106.
Embryonic inner ear, Otocyst, Growth factors, Neurotrophin, Statoacoustic ganglion, Neuronal survival, Auditory, Vestibular