Effects of age and sex on the expression of estrogen receptor α and β in the mouse inner ear

Abstract

Conclusion: Estrogen receptor (ER) α and β were expressed in the inner ear, and expression decreased with increasing age. ERα may alter cochlear and vestibular sensory transduction, and ERβ may have a neuroprotective function in the inner ear. Objective: Expression of ERα and ERβ in the mouse inner ear and its alterations with sex and aging were analyzed. Materials and methods: Male and female CBA/J mice aged 8 weeks and 24 months were used. The localization and the intensity of ERα and ERβ immunoreactivity in the inner ear of young and old mice of both sexes were investigated by immunohistochemistry. Results: ERα and ERβ were co-expressed in the inner ear, i.e. in the nuclei of stria vascularis, outer and inner hair cells, spiral ganglion cells and vestibular ganglion cells, vestibular dark cells and endolymphatic sac. Strial marginal cells, outer hair cells and type II ganglion cells showed less expression of ERα. No gender- or age-related difference was noted in the expression pattern of ERα or ERβ, but fluorescence intensity of ERα was stronger in young female mice than in young male mice. In contrast, ERβ revealed no significant difference. In the old mice, fluorescence intensities of both ERα and ERβ were significantly decreased in both sexes.