Molecular Mediators of Estrogen Reduction-induced Otolith Shedding

Objective Previous study suggested that estradiol (E2) plays an important role in otolith shedding by regulating the expression of otoconin 90 (OC90). The purpose of this article is to provide further data on the effect and mechanism of E2 on the morphology of otolith. Methods The rats receiving bilateral ovariectomy (OVX) were used as animal models. Co-immunoprecipitation was used to observe the relationship between estrogen receptor (ER) and estrogen-related receptor alpha (ERR alpha). The morphology of otolith was observed under the scanning electron microscopy. Western blotting and qPCR were used for quantitative analysis of the roles of ER and ERR alpha in regulating OC90 expression. Results The looser otoliths were observed in rats receiving bilateral OVX, which could be reversed by supplementation with E2. The level of ERR alpha was decreased in bilateral OVX rats. ER and ERR alpha interacted with each other on the regulation of the expression of OC90. Conclusion Our results suggest ER and ERR alpha are both important downstream receptors involved in regulating OC90 expression in utricles of rats, and ERR alpha probably functions by interacting with ER. This provides evidence for the mechanism of otolith shedding. And it may be significant for future studies of targeted prevention and therapies for benign paroxysmal positional vertigo.