Prevention of ischemia-induced hearing loss by intravenous administration of hydrogen-rich saline in gerbil.

Abstract

A transient cochlear ischemia model was established in Mongolian gerbils by bilateral vertebral artery occlusion for 15 minutes. Hydrogen-rich saline (5 mL) was administered intravenously immediately after the ischemic insult, with plain saline serving as the control. Seven days post-ischemia, auditory brainstem response (ABR) thresholds at 8 kHz increased by 24.2±3.8 dB and inner hair cell (IHC) counts at the basal cochlear turn declined by 14.1±1.8% in controls. Animals receiving hydrogen-rich saline showed significantly attenuated cochlear injury: ABR threshold elevation was reduced to 11.7±2.6 dB and IHC loss to 7.5±2.1%. Protective effects were more pronounced at higher frequencies (16 and 32 kHz). No changes in ABR thresholds or cochlear histology were observed in non-ischemic animals given either solution.

Mechanism

Hydrogen is proposed to scavenge reactive oxygen species generated during cochlear ischemia-reperfusion, thereby limiting oxidative damage to inner hair cells and preserving auditory function.