In vitro induction of Xenopus oocyte maturation by 4-pregnene-17 alpha, 20 beta-diol-3-one.

Maturation in Xenopus oocyte is initiated by progesterone and other steroids. The possibility that a metabolite of progesterone is the active agent was explored. In the present study the 20 beta-dihydro metabolite of progesterone, 4-pregnene-17 alpha, 20 beta-diol-3-one was found to be as potent as progesterone at concentrations of 0.5 to 3.0 microM in inducing germinal vesicle breakdown (GVBD) in Xenopus oocytes. The order of relative potencies of the steroids tested were progesterone approximately equal to 17 alpha-hydroxy-20 beta-dihydroprogesterone greater than 17 alpha-hydroxy-20 alpha-dihydroprogesterone greater than 17 alpha-hydroxyprogesterone greater than 11-deoxycorticosterone. 17 alpha-hydroxy-20 beta-dihydroprogesterone induces the production of maturation-promoting factor leading to GVBD. The 20 beta-dihydro metabolite may be the active metabolite under in vivo condition.