ON THE MODULATING EFFECTS OF OVARIES ON NEONATAL ANDROGEN PROGRAMMING OF RAT LIVER ENZYMES

ABSTRACT 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 μmole 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 5α-reductase activity and increased levels of 5α-reductase, 16α-hydroxylase and 17α- and 3β-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 5α-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.

HORMONE AND ENZYME ASSAYS IN PREGNANCY

ABSTRACT A rapid and simple method for determination of the placental cystineaminopeptidase (P-CAP) activity in plasma is presented. The enzymecatalysed hydrolysis of the substrate, l-cystine-bis-p-nitroanilide, is followed in a spectrophotometer by reading the absorbance of the product p-nitroaniline at 380 nm. The absorbance increases linearily with time after a lag-period of 30 seconds to 5 min. The reaction is followed for about 10 min. and the increase in absorbtion per min is calculated from the linear part of the absorbtion curve. The test could also be performed by taking 2 readings at about 5 min intervals. In the studies of the enzyme kinetics a competitive inhibitor of the reaction was found in plasma. The amount of the inhibitory substances seemed to be nearly constant in the plasma samples studied from normal pregnant women as well as in plasma samples with high enzyme activity (twin-pregnancy) and low enzyme activity (severe pre-eclampsia). The normal enzyme activity pattern showed an increase from about 210 days of pregnancy and towards the term. A coefficient of correlation of + 0.83 with the more time consuming method using l-cystine-di-βnaphtylamide as substrate was found. It was concluded that the present method could replace the method described by Babuna & Yenen (1966) at least from about 210 days of pregnancy and where a rapid answer is necessary.