J Audiol Otol.  2015 Dec;19(3):111-119. 10.7874/jao.2015.19.3.111.

Noise-Induced Neural Degeneration and Therapeutic Effect of Antioxidant Drugs

• Choi SH
• Choi CH

• KMID: 2167519
• DOI: http://doi.org/10.7874/jao.2015.19.3.111

Abstract

The primary site of lesion induced by noise exposure is the hair cells in the organ of Corti and the primary neural degeneration occurs in synaptic terminals of cochlear nerve fibers and spiral ganglion cells. The cellular basis of noise-induced hearing loss is oxidative stress, which refers to a severe disruption in the balance between the production of free radicals and antioxidant defense system in the cochlea by excessive production of free radicals induced by noise exposure. Oxidative stress has been identified by a variety of biomarkers to label free radical activity which include four-hydroxy-2-nonenal, nitrotyrosine, and malondialdehyde, and inducible nitric oxide synthase, cytochrome-C, and cascade-3, 8, 9. Furthermore, oxidative stress is contributing to the necrotic and apoptotic cell deaths in the cochlea. To counteract the known mechanisms of pathogenesis and oxidative stress induced by noise exposure, a variety of antioxidant drugs including oxygen-based antioxidants such as N-acetyl-L-cystein and acetyl-L-carnitine and nitrone-based antioxidants such as phenyl-N-tert-butylnitrone (PBN), disufenton sodium, 4-hydroxy PBN, and 2, 4-disulfonyl PBN have been used in our laboratory. These antioxidant drugs were effective in preventing or treating noise-induced hearing loss. In combination with other antioxidants, antioxidant drugs showed a strong synergistic effect. Furthermore, successful use of antioxidant drugs depends on the optimal timing of treatment and the duration of treatment, which are highly related to the time window of free radical formation induced by noise exposure.

Keyword

Noise-induced hearing loss; Antioxidant drugs; Neural degeneration; Oxidative stress

MeSH Terms

Acetylcarnitine
Antioxidants
Biomarkers
Cell Death
Cochlea
Cochlear Nerve
Free Radicals
Hair
Hearing Loss, Noise-Induced
Malondialdehyde
Nitric Oxide Synthase Type II
Noise
Organ of Corti
Oxidative Stress
Presynaptic Terminals
Sodium
Spiral Ganglion
Acetylcarnitine
Antioxidants
Free Radicals
Malondialdehyde
Nitric Oxide Synthase Type II
Sodium