In vitro production of estriol from four steroid precursors by rabbit tissues

The production of estriol was demonstrated in intact leukocytes and homogenates of liver, adrenals and ovaries of young adult female rabbits from 17 beta-estriol, testosterone, androst-4-ene-3,17-dione and dehydroepiandrosterone. Androst-4-ene-3,17-dione constituted the best substrate in liver and adrenals and the poorest substrate for estriol production in lymphocytes. Estriol was least readily transformed into estriol in liver and adrenals, while it proved to be the best substrate in ovaries. Phenobarbital administration to rabbits resulted in 49-fold and 23-fold increases in the transformation of androst-4-ene-3,17-dione and dehydroepiandrosterone, respectively, into estriol by lymphocytes. The results indicate that the enzymes involved in estriol biosynthesis in the various tissues respond differently to phenobarbital.