Abstract
Fetal peptide hormones are essential for the development of fetus, which increase
in accordance with pregnancy term. Concentration of these hormones within the feto-placental
unit is normally higher than that of maternal circulation. Since these hormones are
biologically active, the leakage of these hormones into the maternal circulation is
regulated by degradation activity by placental aminopeptidases, in order to maintain
the balance between carriage of pregnancy and onset of labor.
Because the concentration of these hormones, being regulated by the amount of endogenous
production and by physiological degradation by enzymes in the blood and tissue, the
balance between production and degradation is a definitive element for maintaining
normal gestation and term delivery.
The changes of the balance between fetal angiotensin II (A-II) and vasopressin (AVP)
and
A-II and AVP degrading enzymes, between aminopeptidase A (APA) and placental leucine
aminopeptidase( P-LAP) – in the placenta and maternal blood due to fetal stress such
as hypoxia – are the provable causes of preeclampsia or preterm labor.
Induction of APA and P-LAP by estradiol benzoate (E2) and progesterone (P) from placenta
has been demonstrated. They are involved in the regulation of fetal peptide hormones
via placental aminopeptidases in homeostasis of pregnancy.
Recently it was shown that both APA and P-LAP could be potentially safe and effective
drugs for preeclampsia and preterm labor. The authors’ proposed sex steroid treatment
with dose increasing manner by gestational week (sex steroid treatment) for severe
preeclampsia and preterm labor could be candidates replacing conventional treatments.
In light of lacking safe and effective medication, the proposed sex steroid treatment
is worthwhile for the prospective controlled studies for the treatment of both preeclampsia
and preterm labor.
Key words preeclampsia - preterm labor - sex steroid treatment - new role of sex steroid hormones
in pregnancy