Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA305

Poster Communications

Electrophysiology of mammalian cochlear hair cells in aging mice.

J. Jeng1, W. Marcotti1

1. The University of Sheffield, Sheffield, South Yorkshire, United Kingdom.

Mammalian cochlear hair cells are crucial for detecting sound stimuli and transducing them into electrical signals. The degeneration of hair cells is one of the main pathologies associated with age-related hearing loss (ARHL) but the underlying mechanisms are still largely unknown. To better understand age-related changes in hair cell function, we recorded their biophysical properties from aged mice. Whole cell patch clamp was performed to record voltage and current responses from apical coil inner hair cells (IHCs) and outer hair cells (OHCs) of C57BL/6N and C57BL/6J mouse strains at 1, 6 and 12 months. These mice are a model for early onset ARHL and have a mutation in cadherin 23 (CDH23), a protein crucial for the function of mechanically sensitive stereociliary bundles of hair cells. To investigate the possible effect of the CDH23 mutation in C57BL/6N and C57BL/6J mice, we compared them with mice in which the mutation has been repaired with CRISPR/Cas9 (Repaired mice). We found no obvious deficits in the hair cells from all strains at 1 month. Cell membrane capacitance, which is a measure of their surface area, in OHCs and IHCs decreases with age in all mouse strains. While the size of calcium current in IHCs was similar between strains and ages, the potassium current was smaller in Repaired mice at 12 months. Our results suggest that the hair cells in ageing mice are smaller in size but retain their characteristic current profile. The CDH23 mutation may not be the only factor for the changes in hair cells between young and older mice. Ongoing research will provide more evidence on whether the hair cells are normally innervated by the neurons and if they experience oxidative stress with age.

Where applicable, experiments conform with Society ethical requirements