Imperato-McGinley J, Binienda Z, Gedney J, Vaughan E D
Endocrinology. 1986 Jan;118(1):132-7. doi: 10.1210/endo-118-1-132.
In the rat, androgens are responsible for sexually dimorphic nipple differentiation. Nipples are expressed in the female, while in the male, the nipple anlage regress prenatally. Mammary gland development is present in both sexes. Treatment of pregnant Sprague-Dawley rats from days 12-21 of gestation with the aza-steroid 17 beta-N,N-diisopropylcarbamoyl-4-aza-5 alpha-androstan-3-one, a competitive inhibitor of the enzyme 5 alpha-reductase, resulted in nipple development in male offspring. Additionally, there was feminization of the external genitalia, with urethral displacement to the base of the phallus. The role of androgens in suppression of nipple anlage in the male rat fetus is known. This study, however, suggests for the first time a selective role for 5 alpha-dihydrotestosterone in regression of the nipple anlage in utero. Thus, 5 alpha-dihydrotestosterone may be critical not only for masculinization of the external genitalia, but also for inhibition of nipple development in the male rat fetus.
在大鼠中，雄激素负责性二态性乳头分化。乳头在雌性中表达，而在雄性中，乳头原基在产前退化。两性均有乳腺发育。在妊娠第12至21天用氮杂甾体17β-N，N-二异丙基氨基甲酰基-4-氮杂-5α-雄甾烷-3-酮（一种5α-还原酶的竞争性抑制剂）处理怀孕的斯普拉格-道利大鼠，导致雄性后代出现乳头发育。此外，外生殖器出现女性化，尿道移位到阴茎基部。雄激素在抑制雄性大鼠胎儿乳头原基中的作用是已知的。然而，这项研究首次表明5α-双氢睾酮在子宫内乳头原基退化中具有选择性作用。因此，5α-双氢睾酮可能不仅对外生殖器男性化至关重要，而且对抑制雄性大鼠胎儿乳头发育也至关重要。
