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L-NAC does not protect B6 rice from age-related hearing loss.
Davis R; Kuo M-W; Stanton S; Canlon B; Krieg E; Alagramam KN
Abstr Midwinter Res Meet Assoc Res Otolaryngol 2006 Feb; 29:178
The C57BL/6J mouse (aka B6) is homozygous for the age related hearing loss allele (ahl) which causes them to begin losing hearing at about 3 months of age. N-acetyl-L-cysteine (aka L-NAC) has been shown to protect the ear from noise-induced hearing loss in chinchillas. This is hypothesized to be due to the ability of L-NAC to cross the blood brain barrier and serve as the precursor to glutathione-the body's natural reactive oxygen species scavenger. Twelve four-week old female B6 mice were divided into two groups-one group received a daily water change including dissolved L-NAC (1 mg/ml) and a control group receiving just a daily water change. Water consumption was monitored. Auditory brainstem responses for 4, 8, 16 and 32 kHz tone bursts were measured monthly until the mice were 8 months of age. Upon completion of the final ABR, mice were sacrificed, cochleae taken and prepared for quantitative whole mount morphological analysis. Hearing loss was measurable in both groups at 16 and 32 kHz. Neither ABR thresholds nor cytocochleograms differed significantly between the two groups. We conclude that L-NAC, at the concentration used here, does not protect against hearing loss in mice from the effects of the Ahl allele. Research supported by a grant from the University Hospitals of Cleveland to KA. "The findings and conclusions in this presentation have not been formally disseminated by NIOSH and should not be construed to represent any agency determination or policy."
Noise-exposure; Exposure-levels; Noise-induced-hearing-loss; Noise-exposure; Noise; Hearing; Hearing-disorders; Hearing-loss; Laboratory-animals; Animals; Cell-damage; Cellular-reactions; Age-factors
Disease and Injury: Hearing Loss
Abstracts of the 29th Midwinter Research Meeting of the Association for Research in Otolaryngology, Febuary 5-9, 2006, Baltimore, Maryland
MD; NJ; MO
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