Expression of a voltage-dependent potassium channel protein (Kv3.1) in the embryonic development of the auditory...

The present study traces the development of a voltage-dependent potassium channel protein (Kv3.1) in the avian homologue of the cochlear nucleus, in the cochleovestibular ganglion, and in the otic epithelium from early developmental stages until near hatching. Immunohistochemistry with antibodies to the carboxy terminus (recognizing the Kv3.1b splice variant) and to the amino terminus (recognizing either form of Kv3.1) was used on Hamburger-Hamilton-staged chicken embryos. There were three periods in the relative levels of immunostaining in these regions. Early (E2-6), when precursor cells proliferate, migrate, and form axons, there was staining when using either antibody. In the middle period (E6-11), marked by hair cell differentiation, dendritic growth, and early synapse formation, staining levels decreased. In the late period (E11-19), when auditory function begins, staining increased rapidly, especially for Kv3.1b. Early Kv3.1 expression occurs in neuronal and hair cell precursors before they differentiate or function. Later, in the otic epithelium, a high level of Kv3.1 in cilia may precede or coincide with the onset of hair cell function. In neurons, some features of its localization correlate with axon outgrowth and synapse formation, others with the onset of neural activity and function.