The ototoxic effect of locally applied kanamycin and furosemide in guinea pigs.

BACKGROUND:Hearing impairment is a growing social and economic issue. New technical or biological approaches aiming hearing rehabilitation or regeneration require animal testing. Therefore, a reproducible and safe model for hearing-impaired animals is essential. NEW METHOD:Intratympanic injection of kanamycin and furosemide was administered for BFA bunt pigmented guinea pigs for either 1 or 2 h. Hearing loss was regularly measured with compound action potential response to click and tone burst stimuli for up to 26 weeks. Hair cell loss and the density of spiral ganglion neurons were histologically analyzed. RESULTS:One week after the exposure, complete hearing loss was observed in 34 ears from the 36 ears treated for 2 h and remained stable during the follow-up. Histology revealed near complete hair cell loss and secondary degeneration of spiral ganglion neurons. COMPARISON WITH EXISTING METHODS:Animal deafening is usually achieved by systemic application of aminoglycoside antibiotics or chemotherapy drugs, although side effects such as nephrotoxicity may occur which can be avoided by local application. With our procedure, unilateral hearing loss model can also be established. CONCLUSIONS:The single intratympanic application of a solution of 200 mg/ml kanamycin and 50 mg/ml furosemide is a stable and reliable deafening method.