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
LM
Department of Otolaryngology and Communicative Sciences, Medical University of South Carolina, Charleston 29425, USA.
Dolnick
R
R
Medd
A
A
Cohan
C S
CS
D000818:Animals; D001681:Biological Assay; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D002642:Chick Embryo; D020934:Ciliary Neurotrophic Factor; D017077:Culture Media, Conditioned; D007758:Ear, Inner / Q000196:embryology / Q000378:metabolism*; D005726:Ganglia, Parasympathetic / Q000166:cytology; D017950:Ganglia, Sensory / Q000378:metabolism*; D009414:Nerve Growth Factors / Q000378:metabolism* / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000494:pharmacology; D020933:Neurotrophin 3; D009620:Nodose Ganglion / Q000166:cytology; D009924:Organ Culture Techniques; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D012668:Trigeminal Ganglion / Q000166:cytology / Q000378:metabolism*
D019208:Brain-Derived Neurotrophic Factor; D020934:Ciliary Neurotrophic Factor; D017077:Culture Media, Conditioned; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D020933:Neurotrophin 3; D011994:Recombinant Proteins