Dietary Soy Prevents Fetal Demise, Intrauterine Growth Restriction, Craniofacial Dysmorphic Features, and Impairments in Placentation Linked to Gestational Alcohol Exposure: Pivotal Role of Insulin and Insulin-like Growth Factor Signaling Networks

Introduction: Prenatal alcohol exposure can impair placentation and cause intrauterine growth restriction (IUGR), fetal demise, and fetal alcohol spectrum disorder (FASD). Previous studies showed that ethanol's inhibition of placental insulin and insulin-like growth factor, type 1 (IGF-1) signaling compromises trophoblastic cell motility and maternal vascular transformation at the implantation site. Since soy isolate supports insulin responsiveness, we hypothesized that dietary soy could be used to normalize placentation and fetal growth in an experimental model of FASD.

Methods: Pregnant Long-Evans rat dams were fed with isocaloric liquid diets containing 0% or 8.2% ethanol (v/v) from gestation day (GD) 6. Dietary protein sources were either 100% soy isolate or 100% casein (standard). Gestational sacs were harvested on GD19 to evaluate fetal resorption, fetal growth parameters, and placental morphology. Placental insulin/IGF-1 signaling through Akt pathways was assessed using commercial bead-based multiplex enzyme-linked immunosorbent assays.

Results: Dietary soy markedly reduced or prevented the ethanol-associated fetal loss, IUGR, FASD dysmorphic features, and impairments in placentation/maturation. Furthermore, ethanol's inhibitory effects on the placental glycogen cell population at the junctional zone, invasive trophoblast populations at the implantation site, maternal vascular transformation, and signaling through the insulin and IGF1 receptors, Akt and PRAS40 were largely abrogated by co-administration of soy.

Conclusion: Dietary soy may provide an economically feasible and accessible means of reducing adverse pregnancy outcomes linked to gestational ethanol exposure.