title: A characteristic of aspirin-induced hearing loss in auditory brainstem response of conscious rats.
abstract: The acute effects of aspirin on auditory functions were examined electrophysiologically in conscious rats with chronically implanted electrodes for auditory brainstem response (ABR) recording. A single intravenous injection of aspirin at a dose of 225 mg/kg caused a reduction in the amplitude of the ABR P1 wave evoked by a 2 kHz tone pip 1 and 24 hr after dosing at almost all sound intensity levels, while the P1 amplitude at 4 kHz was reduced mainly 1 hr after dosing, and the P1 amplitude at 8 kHz was not significantly affected at middle and high intensities even 1 hr after dosing. The audiogram obtained from the P1 amplitude showed a significant increase in the sound threshold 1 and 24 hr after dosing at 2 kHz, and 1 hr after dosing at 4 kHz, but not at 8 kHz. The peak latency of the P1 wave was also prolonged. Furthermore, reduction of the P2 and P4 wave amplitude and prolongation of the P1-P2 and P2-P4 interpeak latency were also observed at 2 kHz but not a 4 or 8 kHz. These results suggest that the rat auditory function for low frequency is vulnerable to the effects of aspirin. This paradigm, i.e., frequency selectivity, n rats may be useful to further assess the different outer hair cells along the cochlear duct and provide additional evidence for the mechanism(s) or site underlying aspirin ototoxicity.
authors.affiliation: Drug Safety Research Laboratories, Takeda Chemical Industries, Ltd., Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kurata
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: R
authors.initials: R
authors.lastname: Tsukuda
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: S
authors.initials: S
authors.lastname: Sato
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001241:Aspirin / Q000633:toxicity*; D001933:Brain Stem / Q000187:drug effects / Q000503:physiopathology*; D003051:Cochlea / Q000502:physiology / Q000503:physiopathology; D004594:Electrophysiology; D006313:Hearing Loss, Central / Q000139:chemically induced* / Q000503:physiopathology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time
chemical_list: D001241:Aspirin