USEFULNESS OF THE ESTROGEN RELEASING SILASTIC TUBING

We have clarified that when estrogen is administered to immature castrated rats, the seminal vesicle is more responsive than other accessory sex organs, and we are using this experimental model to study the proliferation of the stroma in the male accessory sex organs. In this study we used this experimental model to investigate the usefulness of the estrogen releasing silastic tubing as an alternative administration method to the continuous injection method. Silastic tubing was filled with 17β-estradiol-3-benzoate (E2). The E2-silastic tubing was then subcutaneously implanted into the backs of immature castrated rats, and treatments were performed for 112 weeks. At 1, 2, 3, 6 and 12 weeks after the administration of estrogen, the rats were sacrificed and the serum estradiol-17β concentration and the weight of the seminal vesicle were determined. As well as histological analysis, comparisons were made with the subcutaneous continuous injection method (5 μg/day). The average serum estradiol-17β concentration was 120.0 ± 89.8pg/ml for weeks 12 with the injection method, and 118.2 ± 64.8pg/ml for weeks 112 with the E2-silastic tubing. As with the injection method, proliferation of stroma, a characteristic effect of estrogen, was seen in the seminal vesicle. The weight of the seminal vesicle increased almost linearly for the first 6 weeks. These results suggest that the silastic tubing method is useful as a continuous administration method for estrogen.