Effect of Ginkgo biloba extract on endotoxin-induced labyrinthitis

There are no reports on the therapeutic effect of Ginkgo biloba extract (GBE) on otitis media-induced labyrinthitis. The present study examined whether GBE can protect against cochlear damage induced by intratympanic instillation of lipopolysaccharide (LPS)-induced labyrinthitis.

Experiments were performed in 20 healthy young male guinea pigs. The control group (n=10) received an intratympanic instillation of LPS (20 μl, 3mg/ml). The experimental group (n=10) received intratympanic instillation of LPS immediately after instillation of GBE (10mg/kg) and then experimental groups received GBE (100mg/kg) by intraperitoneal injection every day for 3 days. Instillation of LPS or LPS immediately after GBE was done in the right ear; the untreated left ear was considered normal. Physiological and morphological changes were evaluated.

Statistical analysis of treatment of GBE revealed significantly less hearing loss than LPS group (p<0.05). The ratio of the value of cochlear blood flow (CBF) compared to untreated left side was significantly higher in the GBE treated group than in the LPS-treated group (p<0.05). This result indicated the recovery of CBF in GBE treated group compared to LPS treated group. In the LPS group, scanning electron microscopy revealed hair cell damage with edema. Missing stereocilia in the third layer of the outer hair cell was revealed. However, both the inner hair cells and the outer hair cells had normal appearance in the GBE group. LPS group showed that cochlear Evans blue extravasation was increased strongly in the stria vascularis, spiral limbus, and in the spiral ligament compared with the GBE treated group.

GBE significantly minimizes cochlear damage against LPS-induced otitis media with labyrinthitis in a guinea pig model. GBE has potential as an adjunctive therapy to antibiotics in the treatment of acute otitis media with complicated labyrinthitis.