Cochlear findings in the white spotting (Ws) rat

Area of Science:

• Ototolaryngology
• Genetics
• Developmental Biology

Background:

• White spotting (Ws) rats carry a c-kit gene mutation at the W locus.
• This mutation affects the development of the stria vascularis, a crucial cochlear structure.

Purpose of the Study:

• To investigate the age-related structural and functional changes in the cochlea of Ws/Ws rats.
• To correlate these changes with the c-kit gene mutation.

Main Methods:

• Light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).
• Diaminobenzidine (DAB) staining for capillary visualization.
• Auditory brainstem response (ABR) for functional assessment.
• Study included 26 homozygous Ws/Ws rats aged 1-6 months.

Main Results:

• Early stages (1 month) showed mild stria vascularis thinning and moderate ABR threshold elevation.
• Progressive degeneration of the stria vascularis and outer hair cell loss observed in unpigmented apical cochlear turns.
• Pigmented basal turns showed better preservation of stria vascularis and organ of Corti.
• DAB staining revealed degradation of strial capillary networks in apical regions.
• Significant age-dependent worsening of cochlear defects and interaural differences in degeneration by 6 months.

Conclusions:

• The c-kit gene mutation in Ws/Ws rats leads to progressive cochlear degeneration, particularly affecting the stria vascularis and outer hair cells in apical regions.
• Age and pigmentation status significantly influence the severity and progression of cochlear pathology.
• Ws/Ws rats serve as a valuable model for studying age-related hearing loss and the role of c-kit in cochlear development and maintenance.