Abstract
The mammary growth following the estrogen injection into the ovariectomized immature mice of DS colony was studied using the ductal extension of the third thoracic mammary gland as a criterion. A rapid growth of the gland was achieved by the daily subcutaneous application of estradiol as little as 0.03μg a day for 9days after ovariectomy. A variety of steroids were subcutaneously injected daily along with the estrogen treatment for 9days. 5α-Androstan-17β-ol-3-one and its 2-substituents, dromostanolone propionate, oxymetholone and 17α-methyl dromostanolone, strongly inhibited the estrogen-stimulated mammary duct growth. The reduction of 3-one and/or oxidation of 17β-ol in 5α-androstan-17β-ol-3-one resulted in marked decrease of the inhibitory effect. The introduction of double bond at ring A slightly modified the activity of the parent androstane. On the other hand, potent estrogen antagonists on the uterus, such as 19-nortestosterone, norethisteron, progesterone and MER-25 were almost inactive. These results indicate that there is no direct correlation between the mammary growth inhibiting ability and the androgenic activity or anti-uterotropic activity of a steroid. The biological significance of these estrogen-steroid interactions on the mammary gland development was discussed.
