The investigation of the effect of Korean Red Ginseng on noise-induced hearing loss

Objective: Noise-induced hearing loss is one of most common hearing loss nowadays. There is no treatment method considered to be successful on the hearing loss that has become a permanent nature. The purpose of this study is to evaluate the protective effect of Korean Red Ginseng (KRG) against noise induced hearing loss in a rat animal model. Material and Method: 28 Wistar rats included the study and rats were divided into four different groups. Control serum physiological (SF) (n=7) group was the one which was not taking any treatment, not exposed to noise but given SF (200 mg/kg/day). Control KRG (n=7) group was the one which is not exposed to noise and given KRG (200mg/kg/day) for 10 days. Experimental SF (n=7) group was the one which was exposed to noise and administered SF (200 mg/kg/day). Experimental KRG group (n=7) was administered KRG (200 mg/kg/day) and exposed to noise. 14 rats that were belonged to Experimental SF and Experimental KRG group were exposed to noise at 120 dB SPL and 4 kHz octave band for 5 hours. The hearing status of all animals were evaluated by distortion product otoacoustic emissions (DPOAE) and high frequency auditory brainstem responses (HFABR) at 4, 8, 12, 16 and 32 kHz octave frequencies. HFABR and DPOAE tests we re performed after noise on 1, 7 and 10 days. All animals were sacrificed on day 10th, after last HFABR and DPOAE tests were performed. After sacrification cochlea and spiral ganglion cells were evaluated with hematoxylin-eosin and TUNEL staining by light microscopy. Results: HFABR and histological results demonstrate that experimental KRG group showed better hearing thresholds and reduced cell damage compared with the control group after noise exposure. Although hearing thresholds at all frequencies have been better in the KRG group, significance was only observed at 8 kHz'de (p<0,05). This frequency represents the most traumatic region due to noise for the rat ear. DPOAE responses were lost after the noise. Conclusion: According to these findings, KRG can be used as a usefull antioxidant for noise induced hearing loss. However, there is a need for additional research on protective effect of KRG. Key Words: Noise Induced Hearing Loss, Noise Exposure, Korean Red Ginseng, Antioxidant