[The estrogen-induced changes of estrogen receptor in seminal vesicle of immature castrated rat].

We have already reported that estrogen treatment given to immature castrated rats caused proliferative changes in both collagen and smooth muscle in the seminal vesicles of immature rats detected by light microscopy. Herein, we studied the estrogen-induced changes in estrogen receptor (ER) in the seminal vesicles of immature castrated rats by means of enzyme immunoassay, an immunohistochemical method and RT-PCR, to clarify the mechanism of estrogen induced proliferation of collagen and smooth muscle. Immature rats (3 weeks old) were castrated and left untreated for 3 weeks and then injected subcutaneously with estradiol-17 beta (E2-17 beta, 5 micrograms/day) for 7 days before they were killed. The nuclear ER content per gland, mg tissue and mg protein in the seminal vesicles of castrated rats increased markedly compared with those of non-treated rats. Castration also enhanced ERmRNA expression. The immunohistochemical analysis demonstrated the obvious tissue distribution by which the nuclear ER positive cells were densely distributed in the periglandular stroma. The nuclear ER contents per gland, mg tissue and mg protein in the seminal vesicles of estrogen-treated castrated rats were greater than those in castrated rats. Estrogen treatment further enhanced ERmRNA expression in the castrated rats. The immunohistochemical studies demonstrated that the nuclear ER positive cells appeared among the glandular epithelial cells, basal cells and the peripheral stromal cells, in addition to the periglandular stromal cells. These findings suggest that ER is related to the estrogen induced proliferation of collagen and smooth muscle in the seminal vesicles of immature castrated rats.