Effect of PPARβ/δ agonist on the placentation and embryo-fetal development in rats

The present study was conducted to evaluate the developmental toxicity in the endometrium and placenta due to GW501516 administration by gavage to pregnant rats.GW501516 was orally administered repeatedly to pregnant rats from gestation day (GD) 6 to 17 at a dose of 0, 30, and 100 mg/kg/day. In next study, GW501516 was also orally administered to pregnant rats on GD 7, 8, 9, 10, or 11 at a single dose of 275 or 350 mg/kg. In these studies, caesarean section was performed to examine the pregnancy outcome on GD21. Additionally, GW501516 was orally administered to pregnant rats on GD 10 at a single dose of 275 mg/kg. Placentae were subjected for temporal histological examinations on GD 11, 13, 15, or 17.Placental malformation was induced by repeated administration of GW501516 at a dose of 100 mg/kg/day. Single oral administration of GW501516 at a dose of 275 and/or 350 mg/kg on GD 8, 9, 10, or 11 induced placental malformation, whereas GW501516 administered on GD 10 was the most effective for increasing placental malformation. Histopathologically, single oral administration of GW501516 on GD 10 induced cystic degeneration associated with cellular lysis of glycogen cells started from GD 15 in the basal zone.High frequency of placental malformation was observed by the administration of GW501516. From GD 8 to 11, especially GD 10, is more sensitive period to induce the placental malformation.