Citation

Du X, West MB, Cai Q, Cheng W, Ewert DL, Li W, Floyd RA, Kopke RD. Free Radic. Biol. Med. 2017; 108: 627-643.

Affiliation

Hough Ear Institute, Oklahoma City, OK, USA; Oklahoma Medical Research Foundation, Oklahoma City, OK, USA; Departments of Physiology and Otolaryngology, University of Oklahoma Health Sciences Center, Oklahoma City 73014. Electronic address: rkopke@houghear.org.

Copyright

(Copyright © 2017, Elsevier Publishing)

DOI

10.1016/j.freeradbiomed.2017.04.343

PMID

28438658

Abstract

Cochlear neurodegeneration commonly accompanies hair cell loss resulting from aging, ototoxicity, or exposures to intense noise or blast overpressures. However, the precise pathophysiological mechanisms that drive this degenerative response have not been fully elucidated. Our laboratory previously demonstrated that non-transgenic rats exposed to blast overpressures exhibited marked somatic accumulation of neurotoxic variants of the microtubule-associated protein, Tau, in the hippocampus. In the present study, we extended these analyses to examine neurodegeneration and pathologic Tau accumulation in the auditory system in response to blast exposure and evaluated the potential therapeutic efficacy of antioxidants on short-circuiting this pathological process. Blast injury induced ribbon synapse loss and retrograde neurodegeneration in the cochlea in untreated animals. An accompanying perikaryal accumulation of neurofilament light chain and pathologic Tau oligomers were observed in neurons from both the peripheral and central auditory system, spanning from the spiral ganglion to the auditory cortex. Due to its coincident accumulation pattern and well-documented neurotoxicity, our results suggest that the accumulation of pathologic Tau oligomers may actively contribute to blast-induced cochlear neurodegeneration. Therapeutic intervention with a combinatorial regimen of 2,4-disulfonyl α-phenyl tertiary butyl nitrone (HPN-07) and N-acetylcysteine (NAC) significantly reduced both pathologic Tau accumulation and indications of ongoing neurodegeneration in the cochlea and the auditory cortex. These results demonstrate that a combination of HPN-07 and NAC administrated shortly after a blast exposure can serve as a potential therapeutic strategy for preserving auditory function among military personnel or civilians with blast-induced traumatic brain injuries.

Copyright © 2017. Published by Elsevier Inc.

Language: en

Keywords

Tau protein; antioxidants; auditory system; blast; neurodegeneration; oxidative stress