Brenda M. Jock
Kristen-Lyn Petriello
Lori G. Aldrich
Ann R. Johnson
Roger P. Hamernik
William A. Ahroon
Auditory Res. Lab., State Univ. of New York, Plattsburgh, NY 12901
In the chinchilla, carboplatin has an unusual ototoxic effect on the sensory epithelium of the cochlea [Takono et al., Hear. Res. 75, 93--102 (1994)]. Twelve chinchillas were treated with a single IP or IV injection (50 or 75 mg/kg) of carboplatin. Baseline auditory evoked potential audiograms and cubic distortion product otoacoustic emissions (3DPE) were obtained on each animal. Threshold and 3DPE functions were also acquired at regular intervals between one hour and 30 days post-injection. The sensory epithelium of the cochlea was evaluated using the surface preparation method. Anatomical analysis indicated that the carboplatin caused relatively severe but scattered losses of inner hair cells (IHC) throughout most of the cochlea. The outer sensory cell population was intact and the cells appeared normal at the level of the light microscope. Despite the IHC pathology, which also included vacuolization in the area of the IHCs, evoked potential thresholds, measured at the level of the inferior colliculus were very near normal and 3DPE functions showed very little change. [Work supported by Bristol-Myers Oncology Division and SUNY-Plattsburgh.]