SENSITIVE DEVELOPMENTAL PERIODS FOR KANAMYCIN OTOTOXIC EFFECTS ON DISTORTION-PRODUCT OTOACOUSTIC EMISSIONS

The developing rat is hypersensitive to aminoglycoside toxicity, which is expressed early on as a destruction of outer hair cells (OHC). In the current study, distortion-product otoacoustic emissions (DPOAE), w hich specifically measure the micromechanical activity of OHCs, were u sed to assess functional effects of administering a regimen of kanamyc in to three groups of neonatal rats representing discrete postnatal de velopmental periods. In this manner, pigmented rats were treated at po stnatal days 1-10, 11-20, and 21-30. A series of input-output (I/O) fu nctions obtained for the 2f(1)-f(2) DPOAE during the post-treatment pe riod indicated that detection thresholds were significantly elevated f or the animals treated on postnatal days 1-10 and 11-20, with the grea test elevations observed at the higher test frequencies.