Virilization of the urogenital sinus of the tammar wallaby is not unique to 5 alpha-androstane-3 alpha,17 beta-diol

The androgen 5 alpha -androstane-3 alpha ,17 beta -diol (alpha -adiol) is s ynthesized in testes and secreted into plasma of male tammar wallaby pouch young and appears to virilize the urogenital sinus. To provide insight into its mechanism of action, a dose response study showed that administration of 1 mug 5 alpha -adiol monoenanthate per g body wt. per week for 3 weeks t o 24-day-old female pouch young induced prostate bud formation equivalent t o that of males of the same age, Administration of this same dose of the en anthates of testosterone, dihydrotestosterone, and 5 alpha -adiol to female pouch young caused equivalent virilization of the urogenital sinus. The fa ct that 5 alpha -adiol does not exert a unique effect, together with our ea rlier findings in this species that 5 alpha -adiol and testosterone are con verted to dihydrotestosterone in the urogenital sinus and that virilization of the urogenital sinus is prevented by the androgen receptor antagonist f lutamide, suggest that 5 alpha -adiol is a circulating precursor for dihydr otestosterone formation in this tissue. (C) 2001 Elsevier Science Ireland L td. All rights reserved.