Year: 2012
Type: article
Abstract: The mammalian outer hair cells (OHCs) provide a positive mechanical feedback to enhance the cochlea's hearing sensitivity and frequency selectivity. Although the OHC-specific, somatic motor protein prestin is required for cochlear amplification, it remains unclear whether prestin can provide sufficient cycle-by-cycle feedback. In cochlear mechanical modeling, varying amounts of OHC motor activity should provide varying degrees of feedback efficiency to adjust the gain of cochlear amplifier at resonant frequencies. Here we created and characterized two new prestin-hypomorphic mouse models with reduced levels of wild-type prestin. OHCs from these mice exhibited length, total elementary charge movement (Q(max)), charge density, and electromotility intermediate between those of wild-type and prestin-null mice. Remarkably, measurements of auditory brainstem responses and distortion product otoacoustic emissions from these mice displayed wild-type like hearing sensitivities at 4-22 kHz. These results indicate that as low as 26.7% Q(max), 34.0% charge density and 44.0% electromotility in OHCs were sufficient for wild-type-like hearing sensitivity in mice at 4-22 kHz, and that these in vitro parameters of OHCs did not correlate linearly with the feedback efficiency for in vivo gain of the cochlear amplifier. Our results thus provide valuable data for modeling cochlear mechanics and will stimulate further mechanistic analysis of the cochlear amplifier.
Source: PLoS ONE
Authors: Tetsuji Yamashita, Jie Fang, Jiangang Gao, Yiling Yu, Marcia Mellado Lagarde, Jian Zuo
Institution: St. Jude Children's Research Hospital
Language: English
Subfield: Sensory Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,382
Funders: National Organization for Hearing Research Foundation, St. Jude Children's Research Hospital, Wellcome Trust, American Lebanese Syrian Associated Charities, National Institutes of Health, Office of Naval Research, National Cancer Institute, National Institute on Deafness and Other Communication Disorders
OpenAlex ID: W2011904354