Exp Neurobiol 2020; 29(5): 344-355
Published online October 31, 2020
© The Korean Society for Brain and Neural Sciences
Woo Bin Kim, Kwon-Woo Kang, Kushal Sharma† and Eunyoung Yi*
College of Pharmacy and Natural Medicine Research Institute, Mokpo National University, Muan 58554, Korea
Correspondence to: *To whom correspondence should be addressed.
TEL: 82-61-450-2683, FAX: 82-61-450-2689
†Current affiliation: Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Manville Health Science Building 1664 North Virginia Street MS0352 Reno, NV 89557 USA
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Kv3 family K+ channels, by ensuring speedy repolarization of action potential, enable rapid and high frequency neuronal firing and high precision temporal coding of auditory information in various auditory synapses in the brain. Expression of different Kv3 subtypes within the auditory end organ has been reported. Yet, their precise role at the hair cell synaptic transmission has not been fully elucidated. Using immunolabeling and confocal microscopy we examined the expression pattern of different Kv3 family K+ channel subunits in the nerve fibers innervating the cochlear hair cells. Kv3.1b was found in NKA-positive type 1 afferent fibers, exhibiting high signal intensity at the cell body, the unmyelinated dendritic segment, first heminode and nodes of Ranvier. Kv3.3 signal was detected in the cell body and the unmyelinated dendritic segment of NKA-positive type 1 afferent fibers but not in peripherin-positive type 2 afferent. Kv3.4 was found in ChAT-positive LOC and MOC efferent fibers as well as peripherin-positive type 2 afferent fibers. Such segregated expression pattern implies that each Kv3 subunits participate in different auditory tasks, for example, Kv3.1b and Kv3.3 in ascending signaling while Kv3.4 in feedback upon loud noise exposure.