Analysis of stress-induced hearing loss in repeated cold stress-exposed mice.

Sudden hearing loss is an acute sensorineural hearing loss of unknown etiology. Owing to the significant increase in the number of patients and low efficacy of treatment, elucidation of its pathogenesis is urgently required. An animal model for hearing loss is needed; however, mainstream models, such as noise exposure and drug administration, cause irreversible damage to the inner ear tissue and therefore cannot be said to reflect the pathology of sudden hearing loss, which can sometimes be cured spontaneously. In this study, we prepared a mouse model of hearing loss caused by mental or physical stress due to a sudden change in temperature without directly damaging the inner ear. This mouse model exhibited a tendency toward increased physiological stress and a significant elevation in systemic inflammation. However, no evident structural abnormalities were observed in the inner ears of these mice. In contrast, significant neural activity was observed in the auditory cortices of these mice. Our findings suggested that the onset of hearing loss in these mice may be related to increased systemic inflammation and prominent activity in the auditory cortex caused by excessive stress. Unlike previous mouse models of hearing loss, this stress-induced hearing loss mouse model is the first to be established in which hearing loss is induced by changes in the in vivo environment without causing significant damage to the inner ear tissue. A detailed analysis of this mouse model is expected to elucidate the causes and mechanisms of sudden hearing loss and establish treatment methods.