The synthesis and accumulation of polyamines in reproductive organs of the rat during pregnancy.

The pregnancy of the rat brings about profound changes of the accumulation, biosynthesis and biodegradtion of the polyamines putrescine, spermidine and spermine in the reproductive tissues. 1. In the ovary, the concentration of all polyamines increased markedly around the 12th day of pregnancy. In the uterus, only the concentration of spermine rose at that time. The concentration of purtrescine more than doubled in the fetal part of the placenta around the 15th day of pregnancy, while the low content of putrescine in the maternal placenta did not appreciably change during the progress of pregnancy. Both parts of rat placenta contained relatively high initial concentrations of spermine, which however, rapidly decreased until the term. 2. The activity of ornithine decarboxylase (EC 4.1.1.17) was remarkably high in the placental tissue. The fetal part of the placenta exhibited higher ornithine decarboxylase activity from the very beginning and the enzyme activity also remained at high levels throughout the pregnancy. The initially high orthine decarboxylase activity was very low in the uterus during the early days of pregnancy, however, rapidly increased a few days after the implantation. Uterine ornithine decarboxylase activity reached a maximum on day 12 to 14 of pregnancy and then swiftly decreased. 3. Both parts of the placenta contained high diamine oxidase (EC 1.4.3.6) activity, which, however, rapidly disappeared in the fetal part of the placenta. Although considerably decreasing, the activity of diamine oxidase still was remarkably high in the maternal placenta until the term. No diamine oxidase activity was found in the uterus of normally cycling rats. The enzyme activity was also undetectable in the uterus during the early pregnancy, but abruptly appeared on day 10 of pregnancy, reached a maximum around the 15th day of pregnancy, and therafter gradually decreased until the term. 4. The changes of activity of adenosylmethionine decarboxylase (EC 4.1.1.50) in the uterus and placental tissues resembled those changes found in ornithine decarboxylase activity. The activity of adenosylmethionine decarboxylase also rapidly decreased after day 12 of pregnancy. 5. Uterine diamine oxidase was partially purified (about 30-fold) and its substrate specificity was determined. Diamines putrescine, cadaverine and 1,3-diaminopropane served as most efficient substrates for the enzyme. Some evidence is presented as to indicate that also spermidine and spermine were oxidized by the enzyme, although at much slower rate than the diamines...