Glutathione-S-transferase and NADPH cytochrome P450 reductase activities in rat placenta during pregnancy.

Mammalian gestation depends on the continuous synthesis of steroid hormones such as progesterone, estrogens and gonadotrophic hormones. Placental microsomes are involved in the metabolism of steroid hormones via NADPH cytochrome P450 reductase; this last enzyme is involved in the generation of O2 and H2O2. These partially reduced oxygen forms are scavenged by endogenous antioxidants such as GSH and the related GSH-S-transferase enzyme. The present study has the aim of evaluating whether placental hormonal modification occurring during gestation influences NADPH cytochrome P450 reductase and GSH-S-transferase activities. The results demonstrate a gradual increase of both enzymatic activities which suggests a defense ability of the placenta.