Dexamethasone Effect on Sudden Hearing Loss is Validated in Stress-induced Animal Models: Hypothetical Study

Abstract

BACKGROUND: Stress could be a contributing cause of sudden hearing loss. This study intended to develop an animal model of stress-induced sudden hearing loss and to evaluate the effects of dexamethasone. METHODS: Two stress models (I and II) for rats were designed using various stressors and modified by adjusting the stress protocol to increase the threshold significantly. For the stress model with a significant increase in threshold after stress exposure, changes in cortisol levels according to stress exposure were measured. The threshold shift and the change in the cellular structure associated with stress exposure and dexamethasone administration were analyzed. RESULTS: While hearing thresholds increased only at 16 kHz in rats of stress model I (n = 10), the thresholds increased at 16 and 32 kHz in rats of stress model II (n = 16). Cortisol level increased after stress exposure (P = .015) in stress model II. Among stress model II rats (stress only and stress + dexamethasone groups), the threshold shift at 16 kHz significantly decreased 1 day after dexamethasone injection in the stress + dexa-methasone group (n = 8). Histologically, the cochlear cellularity of the stress + dexamethasone group was more compact than that of the stress-only group (n = 8). CONCLUSION: Our preliminary study presented the development of an animal model of stress-induced sudden hearing loss and the positive results of steroids in terms of hearing recovery.