Age-related hearing loss and expression of antioxidant enzymes in BDF1 mice

Abstract

Conclusion. Our data suggest that the changes in expression of antioxidant enzymes may cause age-related hearing loss (AHL). Objectives. AHL is an aging process of the inner ear, and oxidant stressors are considered to be one of the leading causes. We investigated the hearing level and expression profile of antioxidant enzymes in aged mice. Methods: Mice aged 3, 6, and 11 months were used. Hearing levels of the mice were examined using the auditory brainstem response (ABR). After measuring the ABR threshold, cochleae were dissected. RNA was isolated from the cochleae, and cDNA was synthesized using the retro-transcription enzyme. Expression of the antioxidant enzymes was measured by quantitative real-time PCR. Results: The ABR thresholds of the BDF1 mice were elevated by 6 months of age. The expression of superoxide dismutase 1 (SOD1) and heme oxygenase 1 (HO1) at 11 months of age significantly decreased compared with that of those at 6 months of age. In contrast, a decrease in the expression level was not observed regarding NAD(P)H-quinone oxidoreductase 1 (NQO1).

Keywords::

• Superoxide dismutase 1
• SOD1
• heme oxygenase 1
• HO1
• NAD(P)H-quinone oxidoreductase 1
• NQO1

Acknowledgments

This work was supported by Grants-in-aid for Scientific Research (C) 20591969 and 22791567 from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.