Objective  To investigate regulative effect of estradiol valerate on the expressions of estrogen receptor-alpha (ERα) and -beta (ERβ) in the vagina of rats after ovariectomy.   Methods  A total of 80 adult female SD rats weighing about 340 g were randomly and equally allocated into 4 groups: normal control group

sham operation group

ovariectomized group and drug group. Estradiol valerate (1.2 mg·kg

-1

·d

-1

) was given to the drug group for 4 weeks by gavage in 4 weeks after ovariectomy. Rats from the other 3 group administered

normal saline of same volume by gavage at same time period. Immunohistochemical methods were used to determine ERα and ERβ in superficial and deep compartments in the vagina. The mRNA expression levels of of the 2 subtypes were measured by semi-quantitative RT-PCR.   Results  ERα and ERβ were expressed in squamous epithelial cells

stromal fibroblasts

vascular endothelial cells

and smooth muscle cells

and most in squamous epithelial cells (P0.05). Expression of ERα was significantly stronger than that of ERβ. Expression of ERα in the vagina was significantly up-regulated in drug group(P0.05)

whereas ERβ was not significant changed (P0.05).   Conclusion  ERα is the major subtype of estrogen receptor in vaginal tissue of rats. ERα and ERβ expressions are down-regulated in the vaginal tissues after ovariectomy. Our findings show that estradiol valerate can up-regulate the expression of ERα but ERβ.