Placental toxicity in rats after administration of synthetic glucocorticoids. A morphological, histochemical and immunohistochemical investigation.

Administration of the synthetic glucocorticoids dexamethasone and triamcinolone to pregnant rats between gestational day (GD) 16 and 20 caused dose-dependent placental lesions on GD 21 and 22 which were detected by morphological, histochemical and immunohistochemical means. Maternal blood spaces, trophoblast layer and fetal blood vessels were altered primarily in the centre of the placental labyrinth. Less severe changes were found in the junctional zone, chorionic plate and intraplacental yolk sac. On GD 21, low doses increased the amount of glycogen, while high doses induced a loss of glycogen. gamma-glutamyl transpeptidase activity was increased in the spongiotrophoblast and the labyrinthic trophoblast and dipeptidyl peptidase IV activity in fetal capillary endothelium, whereas alpha-glutamyl aminopeptidase and microsomal alanyl amino-peptidase were not affected. Additionally, in the fetal capillary endothelium an increase of immunoreactivity for the von Willebrand factor occurred. These data suggest that synthetic glucocorticoids affect placental tissues at different and rather specific levels, which may in turn disturb placental function and contribute to fetal maldevelopment.