Coenzyme Q10 and rikkunshito prevent age-related changes in mouse otolith morphology and function

Otoliths play an important role in maintaining body balance, and age-related decline in theis function and morphological integrity can lead to falls. In recent years, the herbal medicine rikkunshito (RKT) and the antioxidant coenzyme Q10 (CoQ10) have been studied for their anti-aging properties; however, their effects on otoliths remain unknown. Therefore, we aimed to investigate whether RKT and CoQ10 can prevent age-related functional and morphological changes in otoliths. To this end, 30 male and 30 female 8-week-old C57BL6N mice were used in this study. The mice were divided into three groups: a control group, CoQ10 group (0.2 % CoQ10 special diet), and RKT group (3 % RKT special diet). At 80 weeks of age, micro-computed tomography (μCT) images were taken and analyzed for otolith volume and CT number. Furthermore, eye movements induced by the linear vestibulo-ocular reflex (LVOR) were analyzed to assess otolith function.

revealed that the RKT group had a significantly smaller volume of the 3 dimensional utriclar CT model (male mice; p = 0.0281, Steel test) and a significantly higher utricular CT number (male mice; p = 0.0104, Dunnett test) than the control group. The RKT group had a significantly weaker LVOR (male mice; lateral 1.3G stimulation; p = 0.00681, Dunnett test) (male mice; longitudinal 1.3G stimulation; p = 0.0183, Dunnett test) (male mice; longitudinal 0.7G stimulation; p = 0.00322, Dunnett test) than the control group. The CoQ10 group exhibited a significantly stronger utricle-induced LVOR than the control group (female mice; lateral 0.7G stimulation; p = 0.0133, Steel test).In conclusion, RKT prevented age-related utricular morphological changes, but did not prevent age-related otolith functional changes in male mice. CoQ10 prevented age-related utricular functional changes for low frequency stimulation in female mice.