Effect of estradiol valerate on the expressions of estrogen receptor subtypes in the uterus of the ovariectomized rats

Objective To investigate the effect of estradiol valerate on the expressions of estrogen receptor (ER) subtypes alpha and beta in the uterus of the ovariectomized rats. Methods A total of 80 female SD rats were randomized to 4 groups: control group, sham-operated group, ovariectomied group, and drug group, 20 for each group. The drug group received daily intragastric estradiol valerate 4 weeks after ovariectomy, the other three groups received the same volume of normal saline. All rats were executed to obtain their uterus 8 weeks following administration. The expressions of ER-α and ER-β were detected in the uterus by immunohistochemistry, so were the levels of mRNA expression of the two ER subtypes by semi-quantitative RT-PCR. Results Both ER-α and ER-β were highly expressed in the normal endometrial epithelium and the glandular epithelial cells, and the ER-α expression was more significant (P0.05). As compared with the control group and sham-operated group, ER-α expression was markedly declined in the ovariectomied group (P0.05). The expression of ER-α was significantly upregulated in the drug group than in the ovariectomied group (P0.05), whereas that of ER-β was not (P0.05). The ER-α/ ER-β ratio was elevated (P0.01). Conclusion Estradiol valerate markedly upregulates the expression of ER-α but has no effect on that of ER-β in the ovariectomized rats.