Optogenetic Control of Mouse Outer Hair Cells

Area of Science:

• Auditory Neuroscience
• Cellular Physiology
• Optogenetics

Background:

• Normal hearing relies on outer hair cell (OHC) amplification, crucial for cochlear function.
• The precise role of OHC force production in amplification and tuning remains unclear.
• Existing OHC manipulation methods lack precision and spatiotemporal resolution.

Purpose of the Study:

• To explore optogenetics using channelrhodopsin-2 (ChR-2) for precise OHC manipulation.
• To assess ChR-2 expression and function in OHCs and auditory cell lines.
• To evaluate the potential of optogenetics for studying cochlear amplification.

Main Methods:

• Adeno-associated virus-mediated gene transfer for ChR-2 expression in murine otocysts.
• ChR-2 expression in the HEI-OC1 auditory cell line.
• ChR-2 conditional expression in mouse OHCs.
• Whole-cell patch-clamp recordings to assess light-induced currents and depolarization.

Main Results:

• Successful ChR-2 expression and light-activated cation currents in mouse OHCs and HEI-OC1 cells.
• Blue light (470 nm) induced depolarization in both cell types.
• OHCs exhibited faster depolarization kinetics (1.45 ms) than HEI-OC1 cells, enabling higher stimulation rates.
• In vivo experiments showed insufficient ChR-2 current for measurable cochlear effects.

Conclusions:

• Channelrhodopsin-2 can be effectively expressed in OHCs and auditory cell lines.
• Optogenetic stimulation elicits light-sensitive currents and depolarization in OHCs.
• The current optogenetic approach, while promising, requires further optimization for in vivo cochlear applications.