Abstract 2280: Folate Protection of Fetal Alcohol Syndrome Related Cardiac Defects by Modulation of Wnt/β-Catenin Signaling
During human pregnancy, alcohol (EtOH) use is linked to induction of congenital heart defects associated with Fetal Alcohol Syndrome (FAS). Exposure of vertebrate embryos by a single injection to binge-drinking ethanol levels induced cardiac and valve defects. Severity of anomalies related to timing of exposure during cardiac specification. To initiate cardiogenesis, the canonical Wnt antagonist Dickkopf-1 acts extracellularly to upregulate Hex an inducer of cardiogenesis. Exposure of stage 4 chick and quail embryos to 30% EtOH suppressed Wnt/β-catenin modulated gene expression of Hex (a marker of the primary heart field) and of Islet-1 (a marker for the second heart field) within the cardiogenic crescent. Exposure of pregnant mice similarly during gastrulation on ED 6.75 to an accepted binge-drinking dose of EtOH (i.e. two i.p. injections of 2.9g/kg of body weight, administered 3 hrs apart) on ED 6.75 (morning of the vaginal plug is ED 0.5) induced atrioventricular and semilunar valve defects, as determined noninvasively by echocardiography on ED15.5. We had shown previously that folic acid (FA) supplementation acts by overriding Wnt/β-catenin inhibition of the induction of cardiac gene expression in the heart fields. Thus, FA, known to protect against neural tube defects, was tested for protective effects against ethanol potentiation of Wnt/β-catenin signaling during cardiac specification. Upon 30% EtOH exposure in the avian model, culture medium supplementation with FA, with and without myoinositol, resulted in normal expression of the cardiac inducers Hex and Islet-1 often at higher levels in the chick heart fields than observed in the physiological saline exposed, control group. In the mouse after EtOH exposure on ED 6.75, FA (10.5 mg/per kg animal chow) supplementation or FA in combination with myo-Inositol provided in the mouse chow beginning with the morning of the vaginal plug, resulted in normal valve development (100%) on ED 15.5 as assessed by echocardiography. In conclusion, folate supplementation alone, or additively in combination with myoinositol, potentiates the suppression of Wnt/β-cat signaling with EtOH exposure allowing induction of normal cardiac gene expression and heart development.