Genetic tools for studying cochlear inhibition
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Updated: May 6, 2026
Culture of Embryonic Mouse Cochlear Explants and Gene Transfer by Electroporation
Published on: January 12, 2015
Eleftheria Slika1, Paul Albert Fuchs1
1The Center for Hearing and Balance, Otolaryngology-Head and Neck Surgery, Johns Hopkins, University School of Medicine Baltimore, Baltimore, MD, United States.
Abstract:
Efferent feedback to the mammalian cochlea includes cholinergic medial olivocochlear neurons (MOCs) that release ACh to hyperpolarize and shunt the voltage change that drives electromotility of outer hair cells (OHCs). Via brainstem connectivity, MOCs are activated by sound in a frequency- and intensity-dependent manner, thereby reducing the amplification of cochlear vibration provided by OHC electromotility. Among other roles, this efferent feedback protects the cochlea from acoustic trauma. Lesion studies, as well as a variety of genetic mouse models, support the hypothesis of efferent protection from acoustic trauma. Genetic knockout and gain-of-function knockin of the unique α9α10-containing nicotinic acetylcholine receptor (nAChR) in hair cells show that acoustic protection correlates with the efficacy of cholinergic inhibition of OHCs. This protective effect was replicated by viral transduction of the gain-of-function α9L9'T nAChR into α9-knockout mice. Continued progress with "efferent gene therapy" will require a reliable method for visualizing nAChR expression in cochlear hair cells. To that end, mice expressing HA-tagged α9 or α10 nAChRs were generated using CRISPR technology. This progress will facilitate continued study of the hair cell nAChR as a therapeutic target to prevent hearing loss and potentially to ameliorate associated pathologies such as hyperacusis.
Insights
Medial olivocochlear neurons protect the cochlea from noise damage by inhibiting outer hair cells. Visualizing nicotinic acetylcholine receptors (nAChRs) in hair cells is key for developing gene therapies to prevent hearing loss.
Area of Science:
- Neuroscience
- Oto-rhino-laryngology
- Genetics
Background:
- Cholinergic medial olivocochlear neurons (MOCs) provide efferent feedback to the mammalian cochlea.
- MOCs release acetylcholine (ACh) to hyperpolarize outer hair cells (OHCs), reducing their amplification of cochlear vibrations.
- This efferent feedback plays a crucial role in protecting the cochlea from acoustic trauma.
Purpose of the Study:
- To investigate the role of the α9α10-containing nicotinic acetylcholine receptor (nAChR) in efferent-mediated acoustic protection.
- To develop a method for visualizing nAChR expression in cochlear hair cells for future gene therapy applications.
Main Methods:
- Utilized genetic mouse models, including knockout and gain-of-function knockin of the α9α10 nAChR.
- Employed viral transduction to deliver gain-of-function nAChRs.
- Generated mice expressing HA-tagged α9 or α10 nAChRs using CRISPR technology.
Main Results:
- Acoustic protection strongly correlated with the efficacy of cholinergic inhibition of OHCs, mediated by the α9α10 nAChR.
- Viral transduction successfully replicated the protective effect in knockout mice.
- Successfully generated mice with tagged nAChRs, enabling visualization in cochlear hair cells.
Conclusions:
- The α9α10 nAChR is critical for efferent-mediated protection against acoustic trauma.
- Visualizing nAChR expression is essential for advancing "efferent gene therapy" strategies.
- Targeting hair cell nAChRs holds promise for preventing hearing loss and treating conditions like hyperacusis.
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