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OTOTOXICITY OF 3,3'-IMINODIPROPIONITRILE: FUNCTIONAL AND MORPHOLOGICAL EVIDENCE OF COCHLEAR DAMAGE
Citation:
Crofton, K., R. Janssen, J. Prazma, S. Pulvar, AND S. Barone, Jr. OTOTOXICITY OF 3,3'-IMINODIPROPIONITRILE: FUNCTIONAL AND MORPHOLOGICAL EVIDENCE OF COCHLEAR DAMAGE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/097.
Description:
Previous reports suggested that IDPN may be ototoxic (Wolff et al. 1977; Crofton and Knight, 1991). The purpose of this research was to investigate the ototoxicity of IDPN using behavioral, physiological and morphological approaches. Three groups of adult rats were exposed to IDPN (0-400 mg/kg/day) for three consecutive days. In the first group, at 9 weeks post-exposure auditory thresholds were determined for 5.3 and 38 kHz tones and BAERs were also recorded to a suprathreshold click stimulus. A second set of animals was tested at 9 weeks for behavioral thresholds to 0.5-40 kHz tones and at 11 weeks post-exposure for brainstem auditory evoked potentials (BAERs) thresholds to 5-80 kHz tones. A third group of animals was dosed (as above) and killed at 12-14 weeks post-exposure for histological assessment. Surface preparations of the organ of Corti were performed to observe hair cells, and mid-modiolar sections of the cochlea were done to examine the spiral ganglion and stria vascularis. Functional data demonstrate a broad-spectrum hearing loss of ranging from 0.5 kHz (30 dB loss) to 80 kHz (40 dB loss). Surface preparations revealed hair cell loss in all turns of the organ of Corti, with a basal-to-apical gradient (more damage in the