Prostaglandin dehydrogenase activity in placenta and in maternal lung, kidney, and gastric mucosa during rat pregnancy.

The purpose of this study was to investigate the changes in prostaglandin dehydrogenase (PGDH) activity in various organs of the rat during pregnancy. PGDH activity was evaluated in lung, kidney, and gastric mucosa of male and nonpregnant female rats, and in these tissues as well as in placenta of pregnant rats at various stages of gestation. The specific activity of PGDH in placenta decreased until day 15 of pregnancy; thereafter, the specific activity of PGDH increased, reaching maximal levels at term. The specific activity of PGDH in lung and kidney tissue of pregnant rats was greater than that in the same tissues of nonpregnant rats; in these tissues the specific activity increased from early pregnancy through day 21 of pregnancy but was decreased significantly on day 22. The specific activity of PGDH in kidney of male rats was significantly greater (10 times) than that in kidney of female rats. This sex-related difference in renal PGDH activity was not found in lung and gastric mucosa. In gastric mucosa, the specific activity of PGDH on day 10 of pregnancy was significantly lower than that in gastric mucosa of nonpregnant rats. A rapid decrease in the specific activity at term was a phenomenon common to lung, kidney, and gastric mucosa, and was distinctly different from the marked increase in the activity in placenta at term. Thus, in this study, we present evidence that the activity of PGDH is modulated in a tissue-specific manner during pregnancy. We speculate that PGDH in maternal, fetal, and placental tissues serves a role in the maintenance of pregnancy and in growth and development of the fetus by regulating the tissue levels of bioactive prostaglandins.