Objective       To study the estrogenic effect of isoflavone derivative F11 in vivo.       Methods        The ovariectomized rat models were constructed

and the rats were divided into a negative control group (normal saline)

a positive control group [estradiol

50 μg/(kg·d)]

a sham operation group and three F11 groups including a F11-15 group

a F11-50 group and a F11-150 group [intraperitoneal injection of F11 with 15

50 and 150 mg/(kg·d)

respectively]. After the treatment for 10 weeks

the ratio of rat uterus wet weight/body weight was analyzed

and the vaginal smear and endometrium were observed by HE staining. The expression of estrogen receptor (ER) α and ERβ in endometrial tissues was determined by Western blotting.       Results       The ratio of rat uterus wet weight/body weight in the F11-50 group and F11-150 group was significant higher than that of the negative control group (P0.05)

but the ratio of the F11-150 group was not significantly different from that of the positive control group or sham operation group (P0.05). There were mainly inflammatory cells in the vaginal smear of the negative control group and keratinized epithelial cells in the vaginal smear of the F11 groups. The HE staining results showed that the quantity of endometrial glands and the size of gland cave in all the three F11 groups were greater than those of the negative control group

and those of the F11-150 were the same as the positive control group and sham operation group. The expression levels of ERα and ERβ in endometrial tissues in the F11 groups were significantly higher than those in the negative control group (P0.05). The ERα expression level of the F11 groups was significantly lower than that of the positive control group and sham operation group (P0.01)

and the ERβ expression level of the F11-150 group was significantly higher than that of the positive control group and sham operation group (P0.05).       Conclusion       F11 exhibits estrogenic effect on increasing uterus wet weight

promoting vaginal epithelium maturation and upregulating ER expression in endometrium of ovariectomized rats mainly through ERβ.