Influence of Day of Pregnancy on Rat Placental, Uterine, and Ovarian Prostaglandin Synthesis and Metabolism

Abstract

Synthesis and metabolism of prostaglandins in reproductive tissues of the gravid rat were studied from the time of post-implantation to just prior to parturition. Rat placental prostaglandin synthesis is low on day 8 of pregnancy, sharply increases on day 11, falls on day 14, and remains at a low level for the remainder of gestation. In the tissue PGE2 synthesis is 6 times greater than that of PGF2alpha on day 11. Prostaglandin metabolism in the placenta was high on day 11, low on days 8 and 14, and elevated on days 16, 18, and 21 of pregnancy. PGE1 metabolism was 8 times greater than that of PGF2alpha. Uterine prostaglandin synthesis was low until day 16, and then increased until the end of pregnancy. PGE2 synthesis was very low in this tissue in comparison to PGF2alpha synthesis. Prostaglandin metabolism in the uterus was relatively low until day 16 and then sharply increased for the remainder of gestation. This increase in metabolism was not directly proportional to uterine growth. PGE1 metabolism was 5 times higher than PGF2alpha metabolism in this organ. Ovarian prostaglandin synthesis was very low in comparison to that of the other reproductive organs. Prostaglandin metabolism in this tissue decreased from day 8 through day 18 of pregnancy. PGE1 metabolism in the ovary was twice that of PGF2alpha. These studies demonstrate patterns for synthesis and metabolism of prostaglandin in each tissue studied which may indicate inter-relationships with the physiological requirements of pregnancy.