[Estradiol regulates the expression of plasma membrane Ca 2+ -ATPase isoform 2 in inner ear of rats].

Objective: To observe the effects of estradiol on expression of plasma membrane Ca ²⁺ -ATPase isoform 2 in inner ear of rats. Methods: Twenty-five Three-months-old female Sprague-Dawley rats were randomly and equally divided into five groups by random number table mathod,with five rats in each group. Animals in Sham group were sham-operated while others were bilateral ovariactmized. One month after modeling, the OVX groups were supplemented with estradiol (E2 group), progesterone (P group), estradiol and progesterone (E2+P group)and vehicle sesame oil (Veh group), while the Sham operation group (Sham group) was supplemented with vehicle sesame oil.All rats were sacrificed and otocysts were obtained immediately. Enzyme-linked immunosorbent assay was used to detect the changes in serum estradiol and progesterone levels of each group of rats before operation, before treatment and before sacrifice. Western blot and quantitative real-time polymerase chain reaction were used to detect the expression of total PMCA2 protein and mRNA in the inner ear of each group. Results: There was no significant difference in serum estradiol and progesterone levels among the five groups before operated( P >0.05). Before treatment, the serum estradiol and progesterone levels of rats in each group were significantly lower than those in Sham group ( P <0.05). The serum estradiol level in E2 group and E2+P group was not significantly different from that in Sham group ( P >0.05), while the serum estradiol level in P group and Veh group was significantly different from that in Sham group ( P <0.05). The level of progesterone in P group and E2+P group was higher than that in Sham group ( P <0.05), while the level of progesterone in Veh group and E2 group was lower than that in Sham group ( P <0.05). Protein and mRNA expression of PMCA2 in P and Veh groups were significantly decreased compared with that of Sham group ( P <0.05) while the expression levels underwent no significantly change in E2 and E2+P groups ( P <0.05). Conclusion: The decrease of serum estradiol level can reduce the expression of otolith regulatory protein PMCA2 in rats, and then affect otolith metabolism, which may be an important link of estrogen affecting otolith metabolism.