Protective Effects Of Korean Red Ginseng On Vestibular Dysfunction And Hearing Loss Of Rats Induced By Intratympanic-Gentamicin Injection

Objective:To investigate the protective effects of Korean Red Ginseng against hearing loss and vestibular dysfunction of rats induced by intratympanic injection (ITI) with gentamicin.Methods:Adult female Sprague-Dawley rats (n=22) were classified into 2 groups, GM group and KRG+GM group. The left ears of GM group (n=12) were treated with GM (ITI.20ul volume of 500mg/ml cone.) every other day for 2weeks and right ears were remained without any management. The KRG+GM group (n=10) was treated.with daily oral feeding of KRG (500mg/kg) starting 7days before ITI and along ITI GM for 2 weeks. ABR test(16 KHz,32KHz) for hearing evaluation and Rotarod treadmill test, head tilt, tail hanging, and swimming test for Balance function were performed at a day of pre-ITI, and post-1,8,15, 22, and 30, respectively. Cochleas and utricles/saccules were harvested for morphological evaluation (SEM/Phalloidin staining).Results:In GM group, the hearing thresholds at 16 and 32 kHz were 58.3±9.9dB and 57.1±8.7dB at post-1 day, and 45.8±9.5dB,42.1±9.1dB at post-30 day. In KRG+GM group, the hearing thresholds at 16 and 32 kHz were 51.0±10.8dB and 51.0±9.9dB at post-1 day, and 41.0±12.4dB,37.5±12.9 dB at post-30 day. Head tilt test showed severe (>40℃) head tilt in 3 rats and moderate (10-40℃) head tilt in 4 rats in GM group but none in KRG+GM group. In GM group, four rats showed uncontrollable head rotation in tail hanging test and five rats revealed abnormal swimming behavior. In KRG+GM group, no abnormal findings were detected in tail hanging and one rat showed prolonged swimming time. SEM and phalloidin staining showed damaged hair cells in cochleas and vestibules which were closely related with functional results.Conclusions:The present study indicated that Korean red ginseng has strong protective effects against vestibular dysfunction but little effect on hearing loss when ototoxicity is induced by unilateral intratympanic injection of GM. The protective effect of morphological evaluation both on vestibular and hearing function was significant.