Prevention of impulse noise-induced hearing loss with antioxidants.

Abstract

CONCLUSION:

These findings indicate a strong protective effect of ALCAR and NAC on impulse noise-induced cochlear damage, and suggest the feasibility of using clinically available antioxidant compounds to protect the ear from acute acoustic injury.

OBJECTIVE:

Reactive oxygen species have been shown to play a significant role in noise-induced hearing loss. In the current study, the protective effects of two antioxidants, acetyl-L-carnitine (ALCAR) and N-L-acetylcysteine (NAC), were investigated in a chinchilla model of hearing loss resulting from impulse noise. It was hypothesized that pre- and post-treatment with these antioxidants would ameliorate the effects of impulse noise compared to saline-treated controls.

MATERIAL AND METHODS:

Eighteen animals were randomly assigned to 1 of 3 groups and exposed to impulse noise at a level of 155 dB peak SPL for 150 repetitions. ALCAR or NAC were administered twice daily (b.i.d.) for 2 days and 1 h prior to and 1 h following noise exposure, and then b.i.d. for the following 2 days. For the control group, saline was injected at the same time points. Auditory brainstem responses (ABRs) were recorded. Cochlear surface preparations were made to obtain cytocochleograms.

RESULTS:

Three weeks after exposure, permanent threshold shifts for the experimental groups were significantly reduced to approximately = 10-30 dB less than that for the control group (p < 0.01). Less hair cell loss was also observed in the ALCAR and NAC groups than in the control group.

• Authors: Richard Kopke, Eric Bielefeld, Jianzhong Liu, Jiefu Zheng, Ronald Jackson, Donald Henderson, John K M Coleman
• Journal: Acta oto-laryngologica (Acta Otolaryngol) Vol. 125 Issue 3 Pg. 235-43 (Mar 2005) ISSN: 0001-6489 [Print] England
• PMID: 15966690 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Antioxidants
• Acetylcarnitine
• Acetylcysteine

Topics

• Acetylcarnitine (pharmacology)
• Acetylcysteine (pharmacology)
• Animals
• Antioxidants (pharmacology)
• Chinchilla
• Disease Models, Animal
• Evoked Potentials, Auditory, Brain Stem (drug effects)
• Female
• Hair Cells, Auditory (drug effects, pathology)
• Hearing Loss, Noise-Induced (prevention & control)
• Recovery of Function (drug effects)