Nipple Differentiation in Fetal Male Rats Treated with an Inhibitor of the Enzyme 5α-Reductase: Definition of a Selective Role for Dihydrotestosterone
January 1986
in “
Endocrinology
”
TLDR Blocking a specific enzyme in male rat fetuses leads to the development of nipples and feminized genitalia.
In a 1986 study, researchers treated pregnant Sprague-Dawley rats with a 5α-reductase inhibitor, 17β-N,N-diisopropylcarbamoyl-4-aza-5α-androstan-3-one, from days 12 to 21 of gestation and observed that male offspring developed nipples, which typically regress prenatally in males due to androgen effects. The treatment also caused feminization of the external genitalia in male offspring. This study provided evidence that 5α-dihydrotestosterone, produced by the action of 5α-reductase on testosterone, plays a crucial role in preventing nipple development in male rat fetuses, indicating its importance not only in masculinizing external genitalia but also in the sexual differentiation of nipples.
