The audiological and histopathological effects of astaxanthin in rats exposed to noise

This study investigated the potential protective effect of astaxanthin against noise-induced hearing loss (NIHL) and its capacity to preserve auditory functions.In the study, 5 different groups (n=5 for each group) were formed using a total of 25 male Wistar albino rats. The groups were divided into 5 groups as control (saline only group), noise, noise+ saline group, astaxanthin only group and noise+ astaxanthin group. Noise presented to rats with 4 kHz narrow band at 120 dB SPL for 4 hours. Astaxanthin was administered intraperitoneally at a dose of 10 mg/kg for 5 days after noise. Hearing functions of the subjects were evaluated by Distortion Product Otoacoustic Emission (DPOAE) test at 1, 2, 4, 6, 8 kHz and Auditory Evoked Brainstem Potentials (ABR) test at 4, 8, 12, 16, and 32 kHz. The evaluations were performed at pretest (Day 0), post-noise Day 1, 7 days and 21 days. On day 21, sacrification and dissection of the temporal bone were performed after the final tests. Histopathological and immunohistochemical examinations were performed and the protective effect of astaxanthin was analysed. As a results in the ABR tests, significant differences were observed between the noise-exposed and astaxanthin-treated groups at frequencies of 4, 8, 12, 16, and 32 kHz on days 1, 7, and 21. In the DPOAE test, significant differences were found at 2, 4, and 6 kHz on day 1, while at 8 kHz, significant differences were observed on days 1 and 21. In the group treated with astaxanthin, an increasing trend in the signal-to-noise ratio was observed from day 1 to day 21. Histopathological examinations revealed that astaxanthin reduced tissue damage and provided cellular protection in the groups exposed to noise. İn Conclusion the study demonstrated that astaxanthin has a potential protective effect against NIHL and may be effective in preserving auditory function. Keywords: Astaxanthin, Noise-Induced Hearing Loss, Antioxidant