In vitro conversion of 17α-hydroxyprogesterone to androstenedione by mashed gonads from metamorphic stages of Xenopus laevis

Abstract

After incubation of [4- 14C] 17α-hydroxyprogesterone with testes and ovaries of Xenopus laevis larvae at three stages of climactic metamorphosis and with testes of one group of postmetamorphic animals, [4- 14C] androst-4-ene-3,17-dione was found as the only C 19-steroid metabolite. At the youngest stage (larvae before forearm break through; stage 29–30), the formation of androst-4-ene-3,17-dione per animal was equally low in both sexes. It remained at that same low level for the ovaries, but more than doubled for testes at the later stages of metamorphosis. There was no indication for the formation of testosterone or estrogens. These studies demonstrate the presence of a 17α-hydroxyprogesterone C 17C 20 lyase; they also indicate a pathway for the formation of androst-4-ene-3,17-dione from 17α-hydroxyprogesterone similar to that in mammalian testes and ovaries.