Wilson J D, George F W, Shaw G, Renfree M B
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA.
Biol Reprod. 1999 Aug;61(2):471-5. doi: 10.1095/biolreprod61.2.471.
Virilization of the male urogenital tract of all mammals, including marsupials, is mediated by androgenic hormones secreted by the testes. We have previously demonstrated profound sexual dimorphism in the concentrations of gonadal androgens in pouch young of the tammar wallaby Macropus eugenii during the interval when the urogenital sinus virilizes. To provide insight into the mechanisms by which androgens are transported from the testes to the target tissues, we measured testosterone and dihydrotestosterone in plasma pools from tammar pouch young from the day of birth to Day 150. Plasma testosterone levels were measurable (0.5-2 ng/ml) at all times studied, but there were no differences between males and females. These low concentrations of plasma testosterone appear to be derived from the adrenal glands and not the testes. Plasma dihydrotestosterone levels in plasma pools from these animals were also low and not sexually dimorphic. We conclude that virilization of the male urogenital tract cannot be explained by the usual transport of testosterone or dihydrotestosterone in plasma but may be mediated by the direct delivery of androgens to the urogenital tract via the Wolffian ducts. Alternatively, circulating prohormones may be converted to androgens in target tissues.
包括有袋类动物在内的所有哺乳动物雄性泌尿生殖道的雄性化是由睾丸分泌的雄激素介导的。我们之前已经证明，在泌尿生殖窦雄性化的这段时间里，尤金袋鼠（Macropus eugenii）育儿袋幼崽的性腺雄激素浓度存在显著的性别差异。为了深入了解雄激素从睾丸运输到靶组织的机制，我们测量了从出生到第150天的尤金袋鼠育儿袋幼崽血浆池中的睾酮和双氢睾酮。在所研究的所有时间点，血浆睾酮水平均可测量（0.5 - 2 ng/ml），但雄性和雌性之间没有差异。这些低浓度的血浆睾酮似乎来源于肾上腺而非睾丸。这些动物血浆池中的血浆双氢睾酮水平也很低，且不存在性别差异。我们得出结论，雄性泌尿生殖道的雄性化不能用血浆中睾酮或双氢睾酮的常规运输来解释，而可能是由雄激素通过沃尔夫管直接输送到泌尿生殖道介导的。或者，循环前体激素可能在靶组织中转化为雄激素。
