Deterioration of hearing function in mice with neural crest defect

Area of Science:

• Oto-genetics
• Neuroscience
• Developmental Biology

Background:

• Melanocytes are crucial for cochlear development and function.
• White-mutant mice (W/Wv, S1/S1d) lack neural crest-derived melanocytes in the stria vascularis.
• Understanding the impact of melanocyte absence on hearing is vital.

Purpose of the Study:

• To investigate the functional consequences of melanocyte absence in the stria vascularis on cochlear potentials and hearing.
• To characterize the progressive hearing loss in W/Wv and S1/S1d mice during postnatal development.

Main Methods:

• Recording cochlear potentials (compound action potential, endocochlear potential) in mutant and control mice.
• In vitro intracellular recordings from stria vascularis cells (marginal and basal cells).
• Comparative analysis of electrophysiological data between mutant and control groups.

Main Results:

• Progressive increase in hearing thresholds and significant hearing loss (up to 40 dB) in mutants compared to controls.
• Endocochlear potential near zero in 6-week-old mutants.
• Abnormal intracellular potentials in stria vascularis marginal and basal cells of mutants, indicating dysfunction.
• Deterioration of receptor function alongside stria vascularis abnormalities.

Conclusions:

• Absence of melanocytes in the stria vascularis leads to progressive hearing loss and cochlear dysfunction in W/Wv and S1/S1d mice.
• The study demonstrates the critical role of melanocytes in maintaining auditory function.
• Dysfunction of stria vascularis and receptor deterioration contribute to hearing impairment in these mutants.