On the modulating effects of ovaries on neonatal androgen programming of rat liver enzymes

The metabolism of 4-[4-14C]androstene-3,17-dione in rat liver microsomal and cytosol fractions was investigated in adult female rats treated with 1.45 mumole of testosterone propionate at birth. The effects of ovariectomy at 14 and 43 days of age on neonatal testosterone imprinting of enzyme levels were studied. Animals spayed 14 days after birth showed a typical masculinized hepatic enzyme activity pattern with a decreased level of the 5alpha-reductase activity and increased level of 5beta-reductase, 16alpha-hydroxylase and 17alpha- and 3beta-hydroxysteroid reductase levels. The pattern was essentially the same in testosterone propionate-treated rats spayed 43 days after birth - with the exception of a feminized 5alpha-reductase activity - whereas a completely feminized ("de-imprinted") pattern of enzyme activities was found in the rats with intact ovaries at the time of death. It is concluded that de-imprinting action of ovaries is mainly of a reversible nature.