EXCRETION OF POLYAMINES BY THE PREGNANT RAT FOLLOWING INHIBITION OF DIAMINE OXIDASE

Rapid growth is associated with elevated activity of ornithine decarboxylase and therefore with increased production of polyamines. It might be expected that pregnancy would give rise to elevated urinary excretion of polyamines, but the increase is, in fact, much smaller than expected. A possible reason is the extremely high activity of placental diamine oxidase in pregnancy that could destroy putrescine. In order to test this hypothesis, pregnant were injected with amino guanidine, an inhibitor of diamine oxidase, and the daily urinary excretions of polyamines were measured as compared with control pregnant and non-pregnant rats. Pregnant rats excreted slightly more polyamines than non-pregnant rats, and showed peak excretions shortly before parturition. Aminoguanidine-treated pregnant rats excreted 5-10 times the amount of putrescine put out by the non-treated controls, and cadaverine excretion was also much higher. The increase in spermidine output by the aminoguanidine-treated rats was less marked. Therefore appears that polyamine synthesis is greatly increased in pregnancy, but that diamine oxidase destroys most of the polyamine produced. © 1979.