Toxic Effect Window of Ovarian Development in Female Offspring Mice Induced by Prenatal Prednisone Exposure with Different Doses and Time

Background Prednisone is one of the most used synthetic glucocorticoids during pregnancy. Epidemiological investigations suggested that prenatal prednisone therapy could affect fetal development, but systematic studies on its effects on ovarian development and the “toxic effect window” remained scarce. Methods In this study, by simulating clinical application characteristics, Kunming mice were given prednisone by oral gavage with different doses (0.25 or 1.0 mg/kg·d) or at different time gestational days (GD) (GD0-9, GD10-18, or GD0-18). Blood and ovaries of fetal mice were collected on GD18, and the serum estradiol level and the related function indexes of ovarian granulosa cells and oocytes were detected. Results Compared with the control group, prenatal prednisone exposure (PPE) induced pathological injury and enhanced cell proliferation in fetal mice ovary. Furthermore, the expression of steroid synthesis functional genes in pre-granulosa cells, the oocyte function markers, and developmentally related genes was enhanced with different doses or at different time of PPE. The Hippo signaling was activated in the fetal ovary of PPE groups. The above changes were most significant in the low or high-dose and full-term PPE groups. Conclusion PPE caused various cell developmental toxicity in the fetal ovary, especially in the low or high-dose, full-term exposure groups. The potential mechanism might be related to the activation of the Hippo signaling pathway.