Changes in the metabolism of PGE1 and PGF2α in rat placenta during pregnancy

The metabolism of PGE₁ and PGF_2α were studied in an in vitro system using placentae from 11-day pregnant rats. PGE₁ was metabolized faster than PGF_2α. The same system was employed to study the quantitative metabolism of these prostaglandins at various stages of pregnancy in the rat. Results of these investigations showed that metabolism became maximal between days 9–12 and between days 15–22 of gestation. On days 12–15 of pregnancy, metabolism decreased, and was at its lowest point on day 14. Maximum prostaglandin metabolism during the sensitive period of days 9–12 of gestation may act as a protective device against the detrimental effects of prostaglandin. Possible correlation of prostaglandin regulation with hormonal balance is discussed.