Expression of neurotrophin receptor trkB in rat cochlear hair cells at time of rearrangement of innervation.
The spatio-temporal distribution of the high-affinity neurotrophin receptor trkB was monitored during postnatal development of the rat cochlea. In addition to expression in presumptive afferent type I collaterals, afferent type II fibers, and efferent fibers, trkB immunoreactivity also transiently appeared in the sensory hair cells themselves, from postnatal days 5-9 in the basal turn, and from postnatal days 9-13 in the apical turn. A comparison of trkB with p75(NGFR), which is expressed in afferent and efferent fibers, and GAP-43 and synaptophysin, which are expressed in efferent fibers, revealed a time/space correlation of trkB receptor expression in hair cells with the rearrangement of their innervation. Co-expression of the neurotrophin receptor and its ligand has been proposed to be functionally involved in regulating the survival of neurons independent of target-derived neurotrophin factor. Thus, the presence of trkB in target hair cells, suggests that auto/paracrine mechanisms play a role during this critical period of rearrangement of neural connections.
Knipper
M
M
Tübingen Center for Hearing Research, Laboratory of Biochemistry, Department of Otolaryngology, University of Tübingen, Röntgenweg 11, D-72076 Tübingen, Germany.
Zimmermann
U
U
Rohbock
K
K
Köpschall
I
I
Zenner
H P
HP
D000818:Animals; D000918:Antibody Specificity; D003051:Cochlea / Q000294:innervation*; D004431:Ear, External / Q000737:chemistry / Q000166:cytology / Q000648:ultrastructure; D007758:Ear, Inner / Q000254:growth & development; D006198:Hair Cells, Auditory / Q000737:chemistry* / Q000648:ultrastructure; D009475:Neurons, Afferent / Q000502:physiology; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology / Q000502:physiology*; D020800:Receptor, Nerve Growth Factor; D020813:Receptor, trkB; D017475:Receptors, Nerve Growth Factor / Q000276:immunology / Q000502:physiology*; D018013:Receptors, Neuropeptide / Q000276:immunology; D016708:Synaptophysin / Q000276:immunology; D013997:Time Factors
D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D018013:Receptors, Neuropeptide; D016708:Synaptophysin; D020794:Receptor Protein-Tyrosine Kinases; D020813:Receptor, trkB