Protective effects of N-acetylcysteine on noise-induced hearing loss in guinea pigs.

Abstract

Increasing evidence suggests the involvement of oxidative stress in noise-induced hearing loss. The present study analysed, in an animal experimental model, the time course of the pathogenic mechanisms of noise-induced cochlear damage and the efficacy of the antioxidant drug N-acetylcysteine in reducing noise ototoxicity. Animals were divided into two groups, exposed to noise one treated with N-acetylcysteine for 3 days and one (the control group) with saline. Acoustic trauma was induced by a continuous pure tone of 6 kHz, at 120 dB SPL for 30 minutes. Electrocochleographic recordings were made from an implanted round window electrode and the compound action potentials were measured daily at 2-16 kHz for 7 days. Morphological changes were analysed by scanning electron microscopy. The acoustic threshold measured 1 hour after acoustic trauma was elevated in the control group to 70-90 dB in the higher frequencies of the compound action potential audiogram, with a maximum threshold elevation ranging between 12 and 16 kHz. During the first 24 h, following acoustic trauma, there was a partial recovery of compound action potential thresholds of about 20 dB to reach a final threshold elevation of about 50-70 dB; there was no further improvement over the remaining experimental week. Animals treated with N-acetylcysteine showed a similar temporary threshold shift but a clear improvement in the recovery of compound action potential thresholds, with significantly reduced permanent threshold shift and hair cell loss. These data suggest that N-acetylcysteine is able to attenuate the toxic effect of acoustic trauma and could represent an interesting molecule for preventing inner ear injuries.

• Authors: A R Fetoni, M Ralli, B Sergi, C Parrilla, D Troiani, G Paludetti
• Journal: Acta otorhinolaryngologica Italica : organo ufficiale della Societa italiana di otorinolaringologia e chirurgia cervico-facciale (Acta Otorhinolaryngol Ital) Vol. 29 Issue 2 Pg. 70-5 (Apr 2009) ISSN: 1827-675X [Electronic] Italy
• PMID: 20111615 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Free Radical Scavengers
• Acetylcysteine

Topics

• Acetylcysteine (therapeutic use)
• Animals
• Female
• Free Radical Scavengers (therapeutic use)
• Guinea Pigs
• Hearing Loss, Noise-Induced (prevention & control)