OS058. Aldosterone deficiency adversely affects pregnancy outcome in mice

In pregnancy, plasma volume is expanded due to high aldosterone levels to support placental perfusion and fetal nutrition. Inadequately low aldosterone levels as present in preeclampsia, a life-threatening disease for both mother and child, are discussed to be involved in its pathogenesis or severity.

We used aldosterone synthase deficient (AS(-/-)) mice to test whether the absence of aldosterone is sufficient to impair pregnancy or even to cause preeclampsia.

AS(-/-) and AS(+/+) females were mated with AS(+/+) and AS(-/-) males, respectively, always generating AS(+/-) offspring. Blood pressure was measured by tail cuff, fetal and placental number and size as well as placental histology were assessed. Placental expression of HIF-1αand angiogenic factors was assessed by semiquantitative RT-PCR.

With maternal aldosterone deficiency in AS(-/-) mice, systolic blood pressure was low before and further reduced during pregnancy and with no increase in proteinuria. Yet, AS(-/-) had smaller litters due to loss of fetuses as indicated by a high number of necrotic placentas with massive lymphocyte infiltrations at gestational day 18. Surviving fetuses and their placentas from AS(-/-) females were smaller. High salt diet before and during pregnancy increased systolic blood pressure only before pregnancy in both genotypes and reduced blood pressure during late pregnancy as compared to normal salt controls. Litter size from AS(-/-) was slightly improved and the differences in placental and fetal weights between AS(+/+) and AS(-/-) mothers disappeared. Overall an increased placental efficiency was observed in both groups.

Our results demonstrate that aldosterone deficiency has profound adverse effects on placental function. High dietary salt intake improved placental function and lowered blood pressure in wild-type mice. In this animal model, aldosterone deficiency did not cause preeclampsia.