Age-related cochlear degeneration in senescence-accelerated mouse

Area of Science:

• Otolaryngology
• Gerontology
• Cell Biology

Background:

• Age-related hearing loss (presbycusis) is a significant health concern.
• Hair cell loss and strial atrophy in the cochlea are key pathological features of presbycusis.
• Murine models are crucial for investigating the mechanisms underlying age-related cochlear changes.

Purpose of the Study:

• To compare age-related cochlear changes, specifically hair cell loss and strial atrophy, between senescence-prone (SAMP1) and senescence-resistant (SAMR1) mouse strains.
• To evaluate the suitability of these mouse strains for studying presbycusis mechanisms.

Main Methods:

• Histological examination of cochlear morphology in SAMP1 and SAMR1 mice at different ages.
• Quantification of inner and outer hair cell populations.
• Assessment of stria vascularis atrophy.

Main Results:

• SAMP1 mice exhibited more rapid age-related loss of inner and outer hair cells compared to SAMR1 mice.
• Both strains showed hair cell loss predominantly at the cochlear apex and base.
• Strial atrophy was observed in both strains, appearing earlier and progressing more rapidly in SAMP1 mice.
• The observed cochlear changes in SAMP1 mice were comparable to those seen in the human cochlea.

Conclusions:

• SAMP1 mice serve as a valuable model for studying accelerated age-related hearing loss due to their rapid hair cell loss and strial atrophy.
• The findings suggest that hearing impairment in senescence-prone mice involves sensory, strial, and neural components of presbycusis.
• These mouse models provide a platform for elucidating the molecular and cellular mechanisms driving age-related cochlear degeneration.