Red ginseng protects against gentamicin-induced balance dysfunction and hearing loss in rats through antiapoptotic functions of ginsenoside Rb1

The authors evaluated the protective effects of Korean red ginseng (KRG) against gentamicin (GM)-induced unilateral vestibular and hearing dysfunction and investigated its effective mechanism using in vitro cell cultures. Vestibular function was comprehensively evaluated by a scoring system that ranged from 0 (normal) to 3 (worst) points, using head tilt, tail hanging, and swimming tests. The GM group showed significantly more deteriorated vestibular function (0 point – 5 rats, 1 point – 1 rat, 2 points – 3 rats, and 3 points – 3 rats) than the KRG + GM group (0 point – 9 rats and 1 point – 1 rat) (p < 0.01). The hearing thresholds were better in the KRG + GM group than in the GM group (p < 0.05). Quantitative analysis of hair cell damage in the scanning electron microscopy was closely related with vestibular and hearing functional results. In vitro study showed that ginsenoside Rb1 (gRb1) attenuated reactive oxygen species production, suppressed JNK activation, up-regulated Bcl-xL and down-regulated Bax, cytochrome c, caspase 3, and cleaved poly (ADP-ribose) polymerase in GM-treated VOT-E36 cells. These findings suggest that KRG including gRb1 component protects against vestibular/hearing dysfunction by inhibiting apoptotic pathways when ototoxicity is induced by unilateral intratympanic injection with GM in rats.