Evaluation of the protective effects of alpha lipoic acid and memantine on noise-induced hearing loss in an animal model

Objective: This study aimed to investigate the potential protective effects of alpha-lipoic acid (ALA), an antioxidant, and memantine (M), a neuroprotective agent, in a rat model of noise-induced hearing loss. Methods: A total of 50 male Wistar Albino rats, weighing 350–400 g on average, were divided into five groups: control, noise, alpha-lipoic acid (ALA), memantine (M), and combination (ALA+M). While no intervention was applied to the control group, the other groups received intraperitoneal administration of the respective agents. The ALA group was administered alpha-lipoic acid (Sigma-Aldrich, Merck, Germany) at a dose of 100 mg/kg/day, and the M group received memantine (Sigma-Aldrich, Merck, Germany) at a dose of 5 mg/kg/day. Noise exposure was performed at 93 dB white noise for 6 hours per day over 7 consecutive days. Administration of the agents began three days prior to noise exposure and continued for a total of seven days. Hearing thresholds were assessed using auditory brainstem responses (ABR), blood samples obtained after sacrifice were analyzed biochemically, and cochlear tissues extracted from the temporal bone were examined histopathologically. Results: At 32 kHz, both the ALA and memantine groups demonstrated significant hearing-protective effects compared to the noise group (p<0.05). Histopathological damage was significantly lower in the ALA group (p<0.05). Although not statistically significant, a protective trend was observed at lower frequencies in the ALA group. Conclusion: ALA exhibited protective effects against hearing loss at both low frequencies (8 and 16 kHz; 30, 40, and 80 dB) and high frequency (32 kHz; 30, 40, and 80 dB). Memantine, on the other hand, showed a protective potential particularly at high frequency. These findings may contribute to the development of therapeutic strategies for the prevention of hearing loss. Keywords: Noise-induced hearing loss, alpha-lipoic acid, memantine, antioxidant, rat model