Role of Oxidative Stress and Antioxidants in Acquired Inner Ear Disorders

Oxygen metabolism in the mitochondria is essential for biological activity, and reactive oxygen species (ROS) are produced simultaneously in the cell. Once an imbalance between ROS production and degradation (oxidative stress) occurs, cells are damaged. Sensory organs, especially those for hearing, are constantly exposed during daily life. Therefore, almost all mammalian species are liable to hearing loss depending on their environment. In the auditory pathway, hair cells, spiral ganglion cells, and the stria vascularis, where mitochondria are abundant, are the main targets of ROS. Excessive generation of ROS in auditory sensory organs is widely known to cause sensorineural hearing loss, and mitochondria-targeted antioxidants are candidates for treatment. This review focuses on the relationship between acquired hearing loss and antioxidant use to provide an overview of novel antioxidants, namely medicines, supplemental nutrients, and natural foods, based on clinical, animal, and cultured-cell studies.

Automated summary

Oxygen metabolism in the mitochondria is crucial for biological activity, but it also produces reactive oxygen species (ROS) in cells. Imbalance between ROS production and degradation can lead to cell damage. Sensory organs, especially those for hearing, are constantly exposed and can cause hearing loss depending on the environment. Hair cells, spiral ganglion cells, and the stria vascularis in the auditory pathway, where mitochondria are abundant, are the main targets of ROS. Excessive ROS in auditory sensory organs are known to cause sensorineural hearing loss, and mitochondria-targeted antioxidants are potential treatments. This review focuses on the relationship between acquired hearing loss and antioxidant use, providing an overview of novel antioxidants, including medications, supplements, and natural foods, based on clinical, animal, and cell culture studies.