Vestibular Hair Cell Regeneration in Guinea Pig after Gentamicin Damage

BACKGROUND AND OBJECTIVES: The recovery of the vestibular sensory epithelia of guinea pigs after gentamicin (GM) induced hair cell injury was assessed both quantitatively and qualitatively with a functional study of the vestibular system using animal rotatory chair. MATERIALS AND METHOD: Evaluations were made via calculating the number of utricle cells bearing hair bundles using scanning electron microscopy (SEM). The number of ampullar hair cells and supporting cells were calculated by toluidine blue staining. Animal rotatory chair test was performed for the evaluation of functional recovery of vestibular system after gentamicin damage in guinea pigs. RESULTS: The initial loss of hair cells in utricle and ampulla were followed by the recovery of hair cell number. The quantitative analyses indicated that the lost hair cells were replaced or regenerated after the end of GM administration, or at 3 months. SEM revealed the morphological recovery of the damaged hair cells and new hair cell regeneration in utricle. In animal rotatory chair test, the gain in slow harmonic acceleration were decreased immediate after GM application, and the gain increased over 3 months. The value of bias off the vertical axis rotation also decreased immediatly after the GM application, and the decreased value of bias were partially recovered. CONCLUSION: We find guinea pig vestibular hair cell regeneration after gentamicin damage with morphologic and functional study