Protective Effect of Yang Mi Ryung® Extract on Noise‐Induced Hearing Loss in Mice

Abstract

Noise-induced hearing loss (NIHL) results from the damage of the delicate hair cells inside the ear after excessive stimulation of noise. Unlike certain lower animals such as amphibians, fishes, and birds, in humans, hair cells cannot be regenerated once they are killed or damaged; thus, there are no therapeutic options to cure NIHL. Therefore, it is more important to protect hair cells from the noise before the damage occurs. In this study, we report the protective effect of Yang Mi Ryung extract (YMRE) against NIHL; this novel therapeutic property of YMRE has not been reported previously. Our data demonstrates that the hearing ability damaged by noise is markedly restored in mice preadministrated with YMRE before noise exposure, to the level of normal control group. Our study also provides the molecular mechanism underlying the protective effect of YMRE against NIHL by showing that YMRE significantly blocks noise-induced apoptotic cell death and reduces reactive oxygen species (ROS) production in cochleae. Moreover, quantitative polymerase chain reaction (qPCR) analysis demonstrates that YMRE has anti-inflammatory properties, suppressing the mRNA levels of TNFα and IL-1β induced by noise exposure. In conclusion, YMRE could be a useful preventive intervention to prevent hearing impairment induced by the exposure to excessive noise.

Correlation of SNR Value on DPOAE Examination with HSP70 Levels in Blood and HSP70 Expression in Cochlea of Noise Model Rattus norvegicus as an Indicator of Inner Ear Damage

“…Meanwhile, exposure to 110 dB noise for 4 hours can induce glutamate excitotoxicity which causes swelling of the cochlear nerve terminals. It is an acute response to noise, which begins with loss of the presynaptic ribbons and postsynaptic terminals of the inner hair cells [20,21]. In their research, Mannstrom et al, explained that when exposed to 110 dB noise intensity for 90 minutes, female Sprague-Dawley albino rats already experienced PTS on the first exposure, while 104 dB noise exposure within 90 minutes was the highest intensity and longest exposure time which can be repeated up to 6 times without causing PTS and rats became resistant to high-intensity noise exposure [21].…”