• Chao Zhang, Elizabeth Flowers, Jun-Xu Li, Qiuju Wang, and Wei Sun.
• Department of Otolaryngology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, PR China; Center for Hearing & Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, 3435 Main Street, Buffalo, NY 14214, United States.
• Behav. Brain Res. 2014 Sep 1; 271: 16-22.

AbstractThe major side-effects of high doses of salicylate include sensorial hearing loss and tinnitus. Although salicylate decreases cochlear output, it enhances the evoked potentials recorded from the central auditory system (CAS), suggesting an increase to sound sensitivity. However, the loudness change after salicylate administration has not yet been directly measured. In this study, we established an operant conditioning based behavioral task in rats and measured their loudness perception changes before and after high doses of salicylate injection (250 mg/kg, i.p.). We found that high doses of salicylate induced a significant increase to loudness response in 40% of the rats (out of 20 rats), suggesting a hyperacusis behavior. In another 40% of rats, a rapid increase of loudness response was detected, suggesting loudness recruitment. The reaction time of the rats was also measured during the loudness tests before and after salicylate exposure. The reaction time level functions are highly correlated to the loudness response functions. Our studies confirmed that increased sound sensitivity, which is commonly seen in patients with tinnitus and hyperacusis, can be induced by high doses of salicylate. This loudness change induced by salicylate may be related with hypersensitivity in the CAS.Copyright © 2014 Elsevier B.V. All rights reserved.

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