Engineering olivocochlear inhibition to reduce acoustic trauma

Area of Science:

• Neuroscience
• Otolaryngology
• Genetics

Background:

• Efferent neurons release acetylcholine, desensitizing cochlear hair cells and protecting against acoustic trauma.
• This protective mechanism is absent in mice lacking efferent inhibition and enhanced by specific nicotinic acetylcholine receptor mutations.

Purpose of the Study:

• To investigate the potential of viral transduction to restore acoustic prophylaxis in efferent knockout mice.
• To assess the efficacy of gene therapy in protecting against noise-induced hearing loss.

Main Methods:

• Utilized viral transduction to deliver gain-of-function nicotinic acetylcholine receptors to hair cells in efferent knockout mice.
• Visualized transgene expression using a fluorophore-conjugated peptide toxin selective for hair cell acetylcholine receptors.
• Measured temporary hearing loss and auditory brain-stem response recovery 1 day post acoustic trauma.

Main Results:

• Viral transduction successfully restored acoustic prophylaxis in efferent knockout mice.
• Treated mice exhibited reduced temporary hearing loss compared to controls.
• Auditory brain-stem response waveforms recovered more rapidly in treated mice, indicating protection of cochlear amplification and afferent signaling.

Conclusions:

• Gene therapy targeting hair cell acetylcholine receptors can effectively protect the inner ear from acoustic trauma.
• Strengthening efferent cochlear feedback via gene therapy offers a promising complementary approach for preventing hearing loss.
• This strategy could be integrated with existing and future hearing loss prevention therapies.