Dose-Dependent Antiteratogenic Effects of Folic Acid on All-Trans Retinoic Acid-Induced Cleft Palate in Fetal Mice

Abstract

Objective Although numerous studies have confirmed that consumption of folic acid (FA) during early pregnancy reduces the risk of oral facial clefts in newborn infants, the optimal dose of FA for reducing this risk remains unknown. We evaluated various doses of FA for their ability to reduce the incidence of all-trans retinoic acid (ATRA)–induced cleft palate in mice. Methods Pregnant C57BL/6J mice were randomly assigned to eight groups dosed with corn oil (control group), ATRA (80 mg/kg), FA (40 mg/kg), or ATRA (80 mg/kg) + FA (2.5 mg, 5 mg, 10 mg, 20 mg, or 40 mg/kg body weight) on gestation day 11 (GD11), after which samples of maternal blood obtained on GD 11 were analyzed for serum folate levels. After receiving the doses, randomly selected mice in each dose group were sacrificed on GDs 13.5, 14.5, and 15.5, and the fetuses were removed for examination by light microscopy and scanning electron microscopy to detect the incidence of cleft palate. Results Among the pregnant mice dosed with ATRA+FA, those dosed with 5 mg/kg FA had fetuses with the lowest incidence of cleft palate. In addition, the eight groups of pregnant mice had significantly different serum folate concentrations ( P < .001). Conclusion When administered to pregnant mice at a specific dose and on the proper gestation day, FA showed an antiteratogenic effect by reducing the incidence of ATRA-induced cleft palate in fetal mice.