Ｇｉｎｓｅｎｏｓｉｄｅ Ｒｂ１による虚血性内耳障害の防御効果

Abstract

Ginsenoside Rb1 (gRb1) is a main ingredient of ginseng root, which has been prescribed to patients for thousands of years in Asian countries without apparent adverse effects. We investigated the protective effects of gRb1 against ischemic damage of the cochlea. Ischemic insult was loaded by occluding the bilateral vertebral arteries for 15min in a gerbil, which lacks posterior communicating arteries causing the cochlea to be nourished solely by the vertebral arteries. GRb1 was dissolved in isotonic saline. Then, 200μL of gRb1 solution (50μg/200μL) was injected into the left femoral vein 1h after inducing ischemia. Hearing was assessed by recording the auditory brainstem responses (ABR). Seven days after ischemia, the animal showed a 22.5dB increase in ABR threshold, 26.5% loss of the inner hair cells at the basal turn, and 19.3 cells/10000μm2 spiral ganglion cell density on average in 6 ears. In the Ischemia-gRb1 group, the ABR threshold increase was 14.2dB, inner hair cell loss was 8.6%, and the density of spiral ganglion cells was 25.8 cells/10000μm2. These findings suggest that gRb1 inhibited ischemic injury of the inner ear.