Degeneration patterns of actin distribution in the organ of corti in two genotypes of mice.

Alterations of the auditory system during ageing and after noise damage have been studied earlier in two genotypes of mice, CBA/Ca and C57BL/6J, the former of which shows a late-onset hearing loss and the latter a high susceptibility to ageing and acoustic trauma early in life. The two strains display similarities to the different types of human age-related hearing loss. In the present study, the different patterns of hair cell degeneration were visualized by phalloidin-labelled actin in the two strains of mice with increasing age. At 1 month of age there were no major differences in the actin distribution between the two genotypes. With increasing age, CBA mice retained a regular pattern of actin content in the cuticular plate but some hair cells were missing. In contrast, the C57BL mice showed a severely distorted architecture of the cutis plate (CP) with less actin labelling, missing hair cells and scar formation. The instability of actin in the hair cells of C57BL mice might result in their high susceptibility to ageing and noise damage.