Electrophysiological Effects of Intratympanic Retinoic Acid Application Following Acoustic Trauma in Rats.

Abstract

Background: Retinoic acid (RA), the active metabolite of vitamin A, is essential for the embryonic development of the inner ear, involving processes such as cell proliferation, differentiation, and morphogenesis. It also plays a crucial role in the protection and maintenance of the inner ear during the postnatal period. This study investigated the electrophysiological effects of early intratympanic RA administration following acoustic trauma.

Methods: Two doses of intratympanic RA injections were administered to 21 Sprague-Dawley rats after acoustic trauma, and the distortion product otoacoustic emissions of all rats were measured after RA injections.

Results: After Noise-Induced Hearing Loss, 2 doses of RA were administered intratympanically, and significant differences were found in signalto-noise ratio (SNR) values at 1, 1.4, 2, 2.8, 4, 6, and 8 kHz frequencies after RA injections (P < .001). In addition, SNR also increased after each RA dose at frequencies of 1.4, 2, 2.8, 6, and 8 kHz (P < .05).

Conclusion: Due to the advancing industry and technology, noise exposure and the resulting hearing loss have become common issues today, and absolute and effective agents for treatment have not yet been achieved. This study found that intratympanic RA injections administered after acoustic trauma have a protective effect against acoustic trauma. However, these results should be supported by further research in humans.