Soybean ß-Conglycinin Prevents Age-Related Hearing Impairment.

ABSTRACT

Obesity-related complications are associated with the development of age-related hearing impairment. ß-Conglycinin (ß-CG), one of the main storage proteins in soy, offers multiple health benefits, including anti-obesity and anti-atherosclerotic effects. Here, to elucidate the potential therapeutic application of ß-CG, we investigated the effect of ß-CG on age-related hearing impairment. Male wild-type mice (age 6 months) were randomly divided into ß-CG-fed and control groups. Six months later, the body weight was significantly lower in ß-CG-fed mice than in the controls. Consumption of ß-CG rescued the hearing impairment observed in control mice. Cochlear blood flow also increased in ß-CG-fed mice, as did the expression of eNOS in the stria vascularis (SV), which protects vasculature. ß-CG consumption also ameliorated oxidative status as assessed by 4-HNE staining. In the SV, lipofuscin granules of marginal cells and vacuolar degeneration of microvascular pericytes were decreased in ß-CG-fed mice, as shown by transmission electron microscopy. ß-CG consumption prevented loss of spiral ganglion cells and reduced the frequencies of lipofuscin granules, nuclear invaginations, and myelin vacuolation. Our observations indicate that ß-CG ameliorates age-related hearing impairment by preserving cochlear blood flow and suppressing oxidative stress.